//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the Expr constant evaluator. // // Constant expression evaluation produces four main results: // // * A success/failure flag indicating whether constant folding was successful. // This is the 'bool' return value used by most of the code in this file. A // 'false' return value indicates that constant folding has failed, and any // appropriate diagnostic has already been produced. // // * An evaluated result, valid only if constant folding has not failed. // // * A flag indicating if evaluation encountered (unevaluated) side-effects. // These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1), // where it is possible to determine the evaluated result regardless. // // * A set of notes indicating why the evaluation was not a constant expression // (under the C++11 / C++1y rules only, at the moment), or, if folding failed // too, why the expression could not be folded. // // If we are checking for a potential constant expression, failure to constant // fold a potential constant sub-expression will be indicated by a 'false' // return value (the expression could not be folded) and no diagnostic (the // expression is not necessarily non-constant). // //===----------------------------------------------------------------------===// #include "clang/AST/APValue.h" #include "clang/AST/ASTContext.h" #include "clang/AST/ASTDiagnostic.h" #include "clang/AST/ASTLambda.h" #include "clang/AST/CharUnits.h" #include "clang/AST/Expr.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/StmtVisitor.h" #include "clang/AST/TypeLoc.h" #include "clang/Basic/Builtins.h" #include "clang/Basic/TargetInfo.h" #include "llvm/ADT/SmallString.h" #include "llvm/Support/raw_ostream.h" #include <cstring> #include <functional> using namespace clang; using llvm::APSInt; using llvm::APFloat; static bool IsGlobalLValue(APValue::LValueBase B); namespace { struct LValue; struct CallStackFrame; struct EvalInfo; static QualType getType(APValue::LValueBase B) { if (!B) return QualType(); if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) return D->getType(); const Expr *Base = B.get<const Expr*>(); // For a materialized temporary, the type of the temporary we materialized // may not be the type of the expression. if (const MaterializeTemporaryExpr *MTE = dyn_cast<MaterializeTemporaryExpr>(Base)) { SmallVector<const Expr *, 2> CommaLHSs; SmallVector<SubobjectAdjustment, 2> Adjustments; const Expr *Temp = MTE->GetTemporaryExpr(); const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); // Keep any cv-qualifiers from the reference if we generated a temporary // for it. if (Inner != Temp) return Inner->getType(); } return Base->getType(); } /// Get an LValue path entry, which is known to not be an array index, as a /// field or base class. static APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) { APValue::BaseOrMemberType Value; Value.setFromOpaqueValue(E.BaseOrMember); return Value; } /// Get an LValue path entry, which is known to not be an array index, as a /// field declaration. static const FieldDecl *getAsField(APValue::LValuePathEntry E) { return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer()); } /// Get an LValue path entry, which is known to not be an array index, as a /// base class declaration. static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer()); } /// Determine whether this LValue path entry for a base class names a virtual /// base class. static bool isVirtualBaseClass(APValue::LValuePathEntry E) { return getAsBaseOrMember(E).getInt(); } /// Find the path length and type of the most-derived subobject in the given /// path, and find the size of the containing array, if any. static unsigned findMostDerivedSubobject(ASTContext &Ctx, QualType Base, ArrayRef<APValue::LValuePathEntry> Path, uint64_t &ArraySize, QualType &Type, bool &IsArray) { unsigned MostDerivedLength = 0; Type = Base; for (unsigned I = 0, N = Path.size(); I != N; ++I) { if (Type->isArrayType()) { const ConstantArrayType *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(Type)); Type = CAT->getElementType(); ArraySize = CAT->getSize().getZExtValue(); MostDerivedLength = I + 1; IsArray = true; } else if (Type->isAnyComplexType()) { const ComplexType *CT = Type->castAs<ComplexType>(); Type = CT->getElementType(); ArraySize = 2; MostDerivedLength = I + 1; IsArray = true; } else if (const FieldDecl *FD = getAsField(Path[I])) { Type = FD->getType(); ArraySize = 0; MostDerivedLength = I + 1; IsArray = false; } else { // Path[I] describes a base class. ArraySize = 0; IsArray = false; } } return MostDerivedLength; } // The order of this enum is important for diagnostics. enum CheckSubobjectKind { CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, CSK_This, CSK_Real, CSK_Imag }; /// A path from a glvalue to a subobject of that glvalue. struct SubobjectDesignator { /// True if the subobject was named in a manner not supported by C++11. Such /// lvalues can still be folded, but they are not core constant expressions /// and we cannot perform lvalue-to-rvalue conversions on them. unsigned Invalid : 1; /// Is this a pointer one past the end of an object? unsigned IsOnePastTheEnd : 1; /// Indicator of whether the most-derived object is an array element. unsigned MostDerivedIsArrayElement : 1; /// The length of the path to the most-derived object of which this is a /// subobject. unsigned MostDerivedPathLength : 29; /// The size of the array of which the most-derived object is an element. /// This will always be 0 if the most-derived object is not an array /// element. 0 is not an indicator of whether or not the most-derived object /// is an array, however, because 0-length arrays are allowed. uint64_t MostDerivedArraySize; /// The type of the most derived object referred to by this address. QualType MostDerivedType; typedef APValue::LValuePathEntry PathEntry; /// The entries on the path from the glvalue to the designated subobject. SmallVector<PathEntry, 8> Entries; SubobjectDesignator() : Invalid(true) {} explicit SubobjectDesignator(QualType T) : Invalid(false), IsOnePastTheEnd(false), MostDerivedIsArrayElement(false), MostDerivedPathLength(0), MostDerivedArraySize(0), MostDerivedType(T) {} SubobjectDesignator(ASTContext &Ctx, const APValue &V) : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), MostDerivedIsArrayElement(false), MostDerivedPathLength(0), MostDerivedArraySize(0) { if (!Invalid) { IsOnePastTheEnd = V.isLValueOnePastTheEnd(); ArrayRef<PathEntry> VEntries = V.getLValuePath(); Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); if (V.getLValueBase()) { bool IsArray = false; MostDerivedPathLength = findMostDerivedSubobject(Ctx, getType(V.getLValueBase()), V.getLValuePath(), MostDerivedArraySize, MostDerivedType, IsArray); MostDerivedIsArrayElement = IsArray; } } } void setInvalid() { Invalid = true; Entries.clear(); } /// Determine whether this is a one-past-the-end pointer. bool isOnePastTheEnd() const { assert(!Invalid); if (IsOnePastTheEnd) return true; if (MostDerivedIsArrayElement && Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize) return true; return false; } /// Check that this refers to a valid subobject. bool isValidSubobject() const { if (Invalid) return false; return !isOnePastTheEnd(); } /// Check that this refers to a valid subobject, and if not, produce a /// relevant diagnostic and set the designator as invalid. bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); /// Update this designator to refer to the first element within this array. void addArrayUnchecked(const ConstantArrayType *CAT) { PathEntry Entry; Entry.ArrayIndex = 0; Entries.push_back(Entry); // This is a most-derived object. MostDerivedType = CAT->getElementType(); MostDerivedIsArrayElement = true; MostDerivedArraySize = CAT->getSize().getZExtValue(); MostDerivedPathLength = Entries.size(); } /// Update this designator to refer to the given base or member of this /// object. void addDeclUnchecked(const Decl *D, bool Virtual = false) { PathEntry Entry; APValue::BaseOrMemberType Value(D, Virtual); Entry.BaseOrMember = Value.getOpaqueValue(); Entries.push_back(Entry); // If this isn't a base class, it's a new most-derived object. if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) { MostDerivedType = FD->getType(); MostDerivedIsArrayElement = false; MostDerivedArraySize = 0; MostDerivedPathLength = Entries.size(); } } /// Update this designator to refer to the given complex component. void addComplexUnchecked(QualType EltTy, bool Imag) { PathEntry Entry; Entry.ArrayIndex = Imag; Entries.push_back(Entry); // This is technically a most-derived object, though in practice this // is unlikely to matter. MostDerivedType = EltTy; MostDerivedIsArrayElement = true; MostDerivedArraySize = 2; MostDerivedPathLength = Entries.size(); } void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N); /// Add N to the address of this subobject. void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { if (Invalid) return; if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement) { Entries.back().ArrayIndex += N; if (Entries.back().ArrayIndex > MostDerivedArraySize) { diagnosePointerArithmetic(Info, E, Entries.back().ArrayIndex); setInvalid(); } return; } // [expr.add]p4: For the purposes of these operators, a pointer to a // nonarray object behaves the same as a pointer to the first element of // an array of length one with the type of the object as its element type. if (IsOnePastTheEnd && N == (uint64_t)-1) IsOnePastTheEnd = false; else if (!IsOnePastTheEnd && N == 1) IsOnePastTheEnd = true; else if (N != 0) { diagnosePointerArithmetic(Info, E, uint64_t(IsOnePastTheEnd) + N); setInvalid(); } } }; /// A stack frame in the constexpr call stack. struct CallStackFrame { EvalInfo &Info; /// Parent - The caller of this stack frame. CallStackFrame *Caller; /// CallLoc - The location of the call expression for this call. SourceLocation CallLoc; /// Callee - The function which was called. const FunctionDecl *Callee; /// Index - The call index of this call. unsigned Index; /// This - The binding for the this pointer in this call, if any. const LValue *This; /// Arguments - Parameter bindings for this function call, indexed by /// parameters' function scope indices. APValue *Arguments; // Note that we intentionally use std::map here so that references to // values are stable. typedef std::map<const void*, APValue> MapTy; typedef MapTy::const_iterator temp_iterator; /// Temporaries - Temporary lvalues materialized within this stack frame. MapTy Temporaries; CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, APValue *Arguments); ~CallStackFrame(); APValue *getTemporary(const void *Key) { MapTy::iterator I = Temporaries.find(Key); return I == Temporaries.end() ? nullptr : &I->second; } APValue &createTemporary(const void *Key, bool IsLifetimeExtended); }; /// Temporarily override 'this'. class ThisOverrideRAII { public: ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable) : Frame(Frame), OldThis(Frame.This) { if (Enable) Frame.This = NewThis; } ~ThisOverrideRAII() { Frame.This = OldThis; } private: CallStackFrame &Frame; const LValue *OldThis; }; /// A partial diagnostic which we might know in advance that we are not going /// to emit. class OptionalDiagnostic { PartialDiagnostic *Diag; public: explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) : Diag(Diag) {} template<typename T> OptionalDiagnostic &operator<<(const T &v) { if (Diag) *Diag << v; return *this; } OptionalDiagnostic &operator<<(const APSInt &I) { if (Diag) { SmallVector<char, 32> Buffer; I.toString(Buffer); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } OptionalDiagnostic &operator<<(const APFloat &F) { if (Diag) { // FIXME: Force the precision of the source value down so we don't // print digits which are usually useless (we don't really care here if // we truncate a digit by accident in edge cases). Ideally, // APFloat::toString would automatically print the shortest // representation which rounds to the correct value, but it's a bit // tricky to implement. unsigned precision = llvm::APFloat::semanticsPrecision(F.getSemantics()); precision = (precision * 59 + 195) / 196; SmallVector<char, 32> Buffer; F.toString(Buffer, precision); *Diag << StringRef(Buffer.data(), Buffer.size()); } return *this; } }; /// A cleanup, and a flag indicating whether it is lifetime-extended. class Cleanup { llvm::PointerIntPair<APValue*, 1, bool> Value; public: Cleanup(APValue *Val, bool IsLifetimeExtended) : Value(Val, IsLifetimeExtended) {} bool isLifetimeExtended() const { return Value.getInt(); } void endLifetime() { *Value.getPointer() = APValue(); } }; /// EvalInfo - This is a private struct used by the evaluator to capture /// information about a subexpression as it is folded. It retains information /// about the AST context, but also maintains information about the folded /// expression. /// /// If an expression could be evaluated, it is still possible it is not a C /// "integer constant expression" or constant expression. If not, this struct /// captures information about how and why not. /// /// One bit of information passed *into* the request for constant folding /// indicates whether the subexpression is "evaluated" or not according to C /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can /// evaluate the expression regardless of what the RHS is, but C only allows /// certain things in certain situations. struct EvalInfo { ASTContext &Ctx; /// EvalStatus - Contains information about the evaluation. Expr::EvalStatus &EvalStatus; /// CurrentCall - The top of the constexpr call stack. CallStackFrame *CurrentCall; /// CallStackDepth - The number of calls in the call stack right now. unsigned CallStackDepth; /// NextCallIndex - The next call index to assign. unsigned NextCallIndex; /// StepsLeft - The remaining number of evaluation steps we're permitted /// to perform. This is essentially a limit for the number of statements /// we will evaluate. unsigned StepsLeft; /// BottomFrame - The frame in which evaluation started. This must be /// initialized after CurrentCall and CallStackDepth. CallStackFrame BottomFrame; /// A stack of values whose lifetimes end at the end of some surrounding /// evaluation frame. llvm::SmallVector<Cleanup, 16> CleanupStack; /// EvaluatingDecl - This is the declaration whose initializer is being /// evaluated, if any. APValue::LValueBase EvaluatingDecl; /// EvaluatingDeclValue - This is the value being constructed for the /// declaration whose initializer is being evaluated, if any. APValue *EvaluatingDeclValue; /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further /// notes attached to it will also be stored, otherwise they will not be. bool HasActiveDiagnostic; /// \brief Have we emitted a diagnostic explaining why we couldn't constant /// fold (not just why it's not strictly a constant expression)? bool HasFoldFailureDiagnostic; /// \brief Whether or not we're currently speculatively evaluating. bool IsSpeculativelyEvaluating; enum EvaluationMode { /// Evaluate as a constant expression. Stop if we find that the expression /// is not a constant expression. EM_ConstantExpression, /// Evaluate as a potential constant expression. Keep going if we hit a /// construct that we can't evaluate yet (because we don't yet know the /// value of something) but stop if we hit something that could never be /// a constant expression. EM_PotentialConstantExpression, /// Fold the expression to a constant. Stop if we hit a side-effect that /// we can't model. EM_ConstantFold, /// Evaluate the expression looking for integer overflow and similar /// issues. Don't worry about side-effects, and try to visit all /// subexpressions. EM_EvaluateForOverflow, /// Evaluate in any way we know how. Don't worry about side-effects that /// can't be modeled. EM_IgnoreSideEffects, /// Evaluate as a constant expression. Stop if we find that the expression /// is not a constant expression. Some expressions can be retried in the /// optimizer if we don't constant fold them here, but in an unevaluated /// context we try to fold them immediately since the optimizer never /// gets a chance to look at it. EM_ConstantExpressionUnevaluated, /// Evaluate as a potential constant expression. Keep going if we hit a /// construct that we can't evaluate yet (because we don't yet know the /// value of something) but stop if we hit something that could never be /// a constant expression. Some expressions can be retried in the /// optimizer if we don't constant fold them here, but in an unevaluated /// context we try to fold them immediately since the optimizer never /// gets a chance to look at it. EM_PotentialConstantExpressionUnevaluated, /// Evaluate as a constant expression. Continue evaluating if we find a /// MemberExpr with a base that can't be evaluated. EM_DesignatorFold, } EvalMode; /// Are we checking whether the expression is a potential constant /// expression? bool checkingPotentialConstantExpression() const { return EvalMode == EM_PotentialConstantExpression || EvalMode == EM_PotentialConstantExpressionUnevaluated; } /// Are we checking an expression for overflow? // FIXME: We should check for any kind of undefined or suspicious behavior // in such constructs, not just overflow. bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; } EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr), CallStackDepth(0), NextCallIndex(1), StepsLeft(getLangOpts().ConstexprStepLimit), BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr), EvaluatingDecl((const ValueDecl *)nullptr), EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), HasFoldFailureDiagnostic(false), IsSpeculativelyEvaluating(false), EvalMode(Mode) {} void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) { EvaluatingDecl = Base; EvaluatingDeclValue = &Value; } const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } bool CheckCallLimit(SourceLocation Loc) { // Don't perform any constexpr calls (other than the call we're checking) // when checking a potential constant expression. if (checkingPotentialConstantExpression() && CallStackDepth > 1) return false; if (NextCallIndex == 0) { // NextCallIndex has wrapped around. FFDiag(Loc, diag::note_constexpr_call_limit_exceeded); return false; } if (CallStackDepth <= getLangOpts().ConstexprCallDepth) return true; FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded) << getLangOpts().ConstexprCallDepth; return false; } CallStackFrame *getCallFrame(unsigned CallIndex) { assert(CallIndex && "no call index in getCallFrame"); // We will eventually hit BottomFrame, which has Index 1, so Frame can't // be null in this loop. CallStackFrame *Frame = CurrentCall; while (Frame->Index > CallIndex) Frame = Frame->Caller; return (Frame->Index == CallIndex) ? Frame : nullptr; } bool nextStep(const Stmt *S) { if (!StepsLeft) { FFDiag(S->getLocStart(), diag::note_constexpr_step_limit_exceeded); return false; } --StepsLeft; return true; } private: /// Add a diagnostic to the diagnostics list. PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); return EvalStatus.Diag->back().second; } /// Add notes containing a call stack to the current point of evaluation. void addCallStack(unsigned Limit); private: OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId, unsigned ExtraNotes, bool IsCCEDiag) { if (EvalStatus.Diag) { // If we have a prior diagnostic, it will be noting that the expression // isn't a constant expression. This diagnostic is more important, // unless we require this evaluation to produce a constant expression. // // FIXME: We might want to show both diagnostics to the user in // EM_ConstantFold mode. if (!EvalStatus.Diag->empty()) { switch (EvalMode) { case EM_ConstantFold: case EM_IgnoreSideEffects: case EM_EvaluateForOverflow: if (!HasFoldFailureDiagnostic) break; // We've already failed to fold something. Keep that diagnostic. case EM_ConstantExpression: case EM_PotentialConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_PotentialConstantExpressionUnevaluated: case EM_DesignatorFold: HasActiveDiagnostic = false; return OptionalDiagnostic(); } } unsigned CallStackNotes = CallStackDepth - 1; unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); if (Limit) CallStackNotes = std::min(CallStackNotes, Limit + 1); if (checkingPotentialConstantExpression()) CallStackNotes = 0; HasActiveDiagnostic = true; HasFoldFailureDiagnostic = !IsCCEDiag; EvalStatus.Diag->clear(); EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); addDiag(Loc, DiagId); if (!checkingPotentialConstantExpression()) addCallStack(Limit); return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); } HasActiveDiagnostic = false; return OptionalDiagnostic(); } public: // Diagnose that the evaluation could not be folded (FF => FoldFailure) OptionalDiagnostic FFDiag(SourceLocation Loc, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { return Diag(Loc, DiagId, ExtraNotes, false); } OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { if (EvalStatus.Diag) return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false); HasActiveDiagnostic = false; return OptionalDiagnostic(); } /// Diagnose that the evaluation does not produce a C++11 core constant /// expression. /// /// FIXME: Stop evaluating if we're in EM_ConstantExpression or /// EM_PotentialConstantExpression mode and we produce one of these. OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { // Don't override a previous diagnostic. Don't bother collecting // diagnostics if we're evaluating for overflow. if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { HasActiveDiagnostic = false; return OptionalDiagnostic(); } return Diag(Loc, DiagId, ExtraNotes, true); } OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, unsigned ExtraNotes = 0) { return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes); } /// Add a note to a prior diagnostic. OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { if (!HasActiveDiagnostic) return OptionalDiagnostic(); return OptionalDiagnostic(&addDiag(Loc, DiagId)); } /// Add a stack of notes to a prior diagnostic. void addNotes(ArrayRef<PartialDiagnosticAt> Diags) { if (HasActiveDiagnostic) { EvalStatus.Diag->insert(EvalStatus.Diag->end(), Diags.begin(), Diags.end()); } } /// Should we continue evaluation after encountering a side-effect that we /// couldn't model? bool keepEvaluatingAfterSideEffect() { switch (EvalMode) { case EM_PotentialConstantExpression: case EM_PotentialConstantExpressionUnevaluated: case EM_EvaluateForOverflow: case EM_IgnoreSideEffects: return true; case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_ConstantFold: case EM_DesignatorFold: return false; } llvm_unreachable("Missed EvalMode case"); } /// Note that we have had a side-effect, and determine whether we should /// keep evaluating. bool noteSideEffect() { EvalStatus.HasSideEffects = true; return keepEvaluatingAfterSideEffect(); } /// Should we continue evaluation after encountering undefined behavior? bool keepEvaluatingAfterUndefinedBehavior() { switch (EvalMode) { case EM_EvaluateForOverflow: case EM_IgnoreSideEffects: case EM_ConstantFold: case EM_DesignatorFold: return true; case EM_PotentialConstantExpression: case EM_PotentialConstantExpressionUnevaluated: case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: return false; } llvm_unreachable("Missed EvalMode case"); } /// Note that we hit something that was technically undefined behavior, but /// that we can evaluate past it (such as signed overflow or floating-point /// division by zero.) bool noteUndefinedBehavior() { EvalStatus.HasUndefinedBehavior = true; return keepEvaluatingAfterUndefinedBehavior(); } /// Should we continue evaluation as much as possible after encountering a /// construct which can't be reduced to a value? bool keepEvaluatingAfterFailure() { if (!StepsLeft) return false; switch (EvalMode) { case EM_PotentialConstantExpression: case EM_PotentialConstantExpressionUnevaluated: case EM_EvaluateForOverflow: return true; case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_ConstantFold: case EM_IgnoreSideEffects: case EM_DesignatorFold: return false; } llvm_unreachable("Missed EvalMode case"); } /// Notes that we failed to evaluate an expression that other expressions /// directly depend on, and determine if we should keep evaluating. This /// should only be called if we actually intend to keep evaluating. /// /// Call noteSideEffect() instead if we may be able to ignore the value that /// we failed to evaluate, e.g. if we failed to evaluate Foo() in: /// /// (Foo(), 1) // use noteSideEffect /// (Foo() || true) // use noteSideEffect /// Foo() + 1 // use noteFailure LLVM_ATTRIBUTE_UNUSED_RESULT bool noteFailure() { // Failure when evaluating some expression often means there is some // subexpression whose evaluation was skipped. Therefore, (because we // don't track whether we skipped an expression when unwinding after an // evaluation failure) every evaluation failure that bubbles up from a // subexpression implies that a side-effect has potentially happened. We // skip setting the HasSideEffects flag to true until we decide to // continue evaluating after that point, which happens here. bool KeepGoing = keepEvaluatingAfterFailure(); EvalStatus.HasSideEffects |= KeepGoing; return KeepGoing; } bool allowInvalidBaseExpr() const { return EvalMode == EM_DesignatorFold; } }; /// Object used to treat all foldable expressions as constant expressions. struct FoldConstant { EvalInfo &Info; bool Enabled; bool HadNoPriorDiags; EvalInfo::EvaluationMode OldMode; explicit FoldConstant(EvalInfo &Info, bool Enabled) : Info(Info), Enabled(Enabled), HadNoPriorDiags(Info.EvalStatus.Diag && Info.EvalStatus.Diag->empty() && !Info.EvalStatus.HasSideEffects), OldMode(Info.EvalMode) { if (Enabled && (Info.EvalMode == EvalInfo::EM_ConstantExpression || Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated)) Info.EvalMode = EvalInfo::EM_ConstantFold; } void keepDiagnostics() { Enabled = false; } ~FoldConstant() { if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && !Info.EvalStatus.HasSideEffects) Info.EvalStatus.Diag->clear(); Info.EvalMode = OldMode; } }; /// RAII object used to treat the current evaluation as the correct pointer /// offset fold for the current EvalMode struct FoldOffsetRAII { EvalInfo &Info; EvalInfo::EvaluationMode OldMode; explicit FoldOffsetRAII(EvalInfo &Info, bool Subobject) : Info(Info), OldMode(Info.EvalMode) { if (!Info.checkingPotentialConstantExpression()) Info.EvalMode = Subobject ? EvalInfo::EM_DesignatorFold : EvalInfo::EM_ConstantFold; } ~FoldOffsetRAII() { Info.EvalMode = OldMode; } }; /// RAII object used to optionally suppress diagnostics and side-effects from /// a speculative evaluation. class SpeculativeEvaluationRAII { /// Pair of EvalInfo, and a bit that stores whether or not we were /// speculatively evaluating when we created this RAII. llvm::PointerIntPair<EvalInfo *, 1, bool> InfoAndOldSpecEval; Expr::EvalStatus Old; void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) { InfoAndOldSpecEval = Other.InfoAndOldSpecEval; Old = Other.Old; Other.InfoAndOldSpecEval.setPointer(nullptr); } void maybeRestoreState() { EvalInfo *Info = InfoAndOldSpecEval.getPointer(); if (!Info) return; Info->EvalStatus = Old; Info->IsSpeculativelyEvaluating = InfoAndOldSpecEval.getInt(); } public: SpeculativeEvaluationRAII() = default; SpeculativeEvaluationRAII( EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr) : InfoAndOldSpecEval(&Info, Info.IsSpeculativelyEvaluating), Old(Info.EvalStatus) { Info.EvalStatus.Diag = NewDiag; Info.IsSpeculativelyEvaluating = true; } SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete; SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) { moveFromAndCancel(std::move(Other)); } SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) { maybeRestoreState(); moveFromAndCancel(std::move(Other)); return *this; } ~SpeculativeEvaluationRAII() { maybeRestoreState(); } }; /// RAII object wrapping a full-expression or block scope, and handling /// the ending of the lifetime of temporaries created within it. template<bool IsFullExpression> class ScopeRAII { EvalInfo &Info; unsigned OldStackSize; public: ScopeRAII(EvalInfo &Info) : Info(Info), OldStackSize(Info.CleanupStack.size()) {} ~ScopeRAII() { // Body moved to a static method to encourage the compiler to inline away // instances of this class. cleanup(Info, OldStackSize); } private: static void cleanup(EvalInfo &Info, unsigned OldStackSize) { unsigned NewEnd = OldStackSize; for (unsigned I = OldStackSize, N = Info.CleanupStack.size(); I != N; ++I) { if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) { // Full-expression cleanup of a lifetime-extended temporary: nothing // to do, just move this cleanup to the right place in the stack. std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]); ++NewEnd; } else { // End the lifetime of the object. Info.CleanupStack[I].endLifetime(); } } Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd, Info.CleanupStack.end()); } }; typedef ScopeRAII<false> BlockScopeRAII; typedef ScopeRAII<true> FullExpressionRAII; } bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { if (Invalid) return false; if (isOnePastTheEnd()) { Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) << CSK; setInvalid(); return false; } return true; } void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N) { if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement) Info.CCEDiag(E, diag::note_constexpr_array_index) << static_cast<int>(N) << /*array*/ 0 << static_cast<unsigned>(MostDerivedArraySize); else Info.CCEDiag(E, diag::note_constexpr_array_index) << static_cast<int>(N) << /*non-array*/ 1; setInvalid(); } CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, APValue *Arguments) : Info(Info), Caller(Info.CurrentCall), CallLoc(CallLoc), Callee(Callee), Index(Info.NextCallIndex++), This(This), Arguments(Arguments) { Info.CurrentCall = this; ++Info.CallStackDepth; } CallStackFrame::~CallStackFrame() { assert(Info.CurrentCall == this && "calls retired out of order"); --Info.CallStackDepth; Info.CurrentCall = Caller; } APValue &CallStackFrame::createTemporary(const void *Key, bool IsLifetimeExtended) { APValue &Result = Temporaries[Key]; assert(Result.isUninit() && "temporary created multiple times"); Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended)); return Result; } static void describeCall(CallStackFrame *Frame, raw_ostream &Out); void EvalInfo::addCallStack(unsigned Limit) { // Determine which calls to skip, if any. unsigned ActiveCalls = CallStackDepth - 1; unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; if (Limit && Limit < ActiveCalls) { SkipStart = Limit / 2 + Limit % 2; SkipEnd = ActiveCalls - Limit / 2; } // Walk the call stack and add the diagnostics. unsigned CallIdx = 0; for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; Frame = Frame->Caller, ++CallIdx) { // Skip this call? if (CallIdx >= SkipStart && CallIdx < SkipEnd) { if (CallIdx == SkipStart) { // Note that we're skipping calls. addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) << unsigned(ActiveCalls - Limit); } continue; } // Use a different note for an inheriting constructor, because from the // user's perspective it's not really a function at all. if (auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Frame->Callee)) { if (CD->isInheritingConstructor()) { addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here) << CD->getParent(); continue; } } SmallVector<char, 128> Buffer; llvm::raw_svector_ostream Out(Buffer); describeCall(Frame, Out); addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); } } namespace { struct ComplexValue { private: bool IsInt; public: APSInt IntReal, IntImag; APFloat FloatReal, FloatImag; ComplexValue() : FloatReal(APFloat::Bogus), FloatImag(APFloat::Bogus) {} void makeComplexFloat() { IsInt = false; } bool isComplexFloat() const { return !IsInt; } APFloat &getComplexFloatReal() { return FloatReal; } APFloat &getComplexFloatImag() { return FloatImag; } void makeComplexInt() { IsInt = true; } bool isComplexInt() const { return IsInt; } APSInt &getComplexIntReal() { return IntReal; } APSInt &getComplexIntImag() { return IntImag; } void moveInto(APValue &v) const { if (isComplexFloat()) v = APValue(FloatReal, FloatImag); else v = APValue(IntReal, IntImag); } void setFrom(const APValue &v) { assert(v.isComplexFloat() || v.isComplexInt()); if (v.isComplexFloat()) { makeComplexFloat(); FloatReal = v.getComplexFloatReal(); FloatImag = v.getComplexFloatImag(); } else { makeComplexInt(); IntReal = v.getComplexIntReal(); IntImag = v.getComplexIntImag(); } } }; struct LValue { APValue::LValueBase Base; CharUnits Offset; unsigned InvalidBase : 1; unsigned CallIndex : 31; SubobjectDesignator Designator; const APValue::LValueBase getLValueBase() const { return Base; } CharUnits &getLValueOffset() { return Offset; } const CharUnits &getLValueOffset() const { return Offset; } unsigned getLValueCallIndex() const { return CallIndex; } SubobjectDesignator &getLValueDesignator() { return Designator; } const SubobjectDesignator &getLValueDesignator() const { return Designator;} void moveInto(APValue &V) const { if (Designator.Invalid) V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex); else V = APValue(Base, Offset, Designator.Entries, Designator.IsOnePastTheEnd, CallIndex); } void setFrom(ASTContext &Ctx, const APValue &V) { assert(V.isLValue()); Base = V.getLValueBase(); Offset = V.getLValueOffset(); InvalidBase = false; CallIndex = V.getLValueCallIndex(); Designator = SubobjectDesignator(Ctx, V); } void set(APValue::LValueBase B, unsigned I = 0, bool BInvalid = false) { Base = B; Offset = CharUnits::Zero(); InvalidBase = BInvalid; CallIndex = I; Designator = SubobjectDesignator(getType(B)); } void setInvalid(APValue::LValueBase B, unsigned I = 0) { set(B, I, true); } // Check that this LValue is not based on a null pointer. If it is, produce // a diagnostic and mark the designator as invalid. bool checkNullPointer(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { if (Designator.Invalid) return false; if (!Base) { Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK; Designator.setInvalid(); return false; } return true; } // Check this LValue refers to an object. If not, set the designator to be // invalid and emit a diagnostic. bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && Designator.checkSubobject(Info, E, CSK); } void addDecl(EvalInfo &Info, const Expr *E, const Decl *D, bool Virtual = false) { if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) Designator.addDeclUnchecked(D, Virtual); } void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { if (checkSubobject(Info, E, CSK_ArrayToPointer)) Designator.addArrayUnchecked(CAT); } void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) Designator.addComplexUnchecked(EltTy, Imag); } void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { if (N && checkNullPointer(Info, E, CSK_ArrayIndex)) Designator.adjustIndex(Info, E, N); } }; struct MemberPtr { MemberPtr() {} explicit MemberPtr(const ValueDecl *Decl) : DeclAndIsDerivedMember(Decl, false), Path() {} /// The member or (direct or indirect) field referred to by this member /// pointer, or 0 if this is a null member pointer. const ValueDecl *getDecl() const { return DeclAndIsDerivedMember.getPointer(); } /// Is this actually a member of some type derived from the relevant class? bool isDerivedMember() const { return DeclAndIsDerivedMember.getInt(); } /// Get the class which the declaration actually lives in. const CXXRecordDecl *getContainingRecord() const { return cast<CXXRecordDecl>( DeclAndIsDerivedMember.getPointer()->getDeclContext()); } void moveInto(APValue &V) const { V = APValue(getDecl(), isDerivedMember(), Path); } void setFrom(const APValue &V) { assert(V.isMemberPointer()); DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); Path.clear(); ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); Path.insert(Path.end(), P.begin(), P.end()); } /// DeclAndIsDerivedMember - The member declaration, and a flag indicating /// whether the member is a member of some class derived from the class type /// of the member pointer. llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; /// Path - The path of base/derived classes from the member declaration's /// class (exclusive) to the class type of the member pointer (inclusive). SmallVector<const CXXRecordDecl*, 4> Path; /// Perform a cast towards the class of the Decl (either up or down the /// hierarchy). bool castBack(const CXXRecordDecl *Class) { assert(!Path.empty()); const CXXRecordDecl *Expected; if (Path.size() >= 2) Expected = Path[Path.size() - 2]; else Expected = getContainingRecord(); if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), // if B does not contain the original member and is not a base or // derived class of the class containing the original member, the result // of the cast is undefined. // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to // (D::*). We consider that to be a language defect. return false; } Path.pop_back(); return true; } /// Perform a base-to-derived member pointer cast. bool castToDerived(const CXXRecordDecl *Derived) { if (!getDecl()) return true; if (!isDerivedMember()) { Path.push_back(Derived); return true; } if (!castBack(Derived)) return false; if (Path.empty()) DeclAndIsDerivedMember.setInt(false); return true; } /// Perform a derived-to-base member pointer cast. bool castToBase(const CXXRecordDecl *Base) { if (!getDecl()) return true; if (Path.empty()) DeclAndIsDerivedMember.setInt(true); if (isDerivedMember()) { Path.push_back(Base); return true; } return castBack(Base); } }; /// Compare two member pointers, which are assumed to be of the same type. static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { if (!LHS.getDecl() || !RHS.getDecl()) return !LHS.getDecl() && !RHS.getDecl(); if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) return false; return LHS.Path == RHS.Path; } } static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, const Expr *E, bool AllowNonLiteralTypes = false); static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info); static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info); static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, EvalInfo &Info); static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, EvalInfo &Info); static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info); static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result); //===----------------------------------------------------------------------===// // Misc utilities //===----------------------------------------------------------------------===// /// Produce a string describing the given constexpr call. static void describeCall(CallStackFrame *Frame, raw_ostream &Out) { unsigned ArgIndex = 0; bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) && !isa<CXXConstructorDecl>(Frame->Callee) && cast<CXXMethodDecl>(Frame->Callee)->isInstance(); if (!IsMemberCall) Out << *Frame->Callee << '('; if (Frame->This && IsMemberCall) { APValue Val; Frame->This->moveInto(Val); Val.printPretty(Out, Frame->Info.Ctx, Frame->This->Designator.MostDerivedType); // FIXME: Add parens around Val if needed. Out << "->" << *Frame->Callee << '('; IsMemberCall = false; } for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { if (ArgIndex > (unsigned)IsMemberCall) Out << ", "; const ParmVarDecl *Param = *I; const APValue &Arg = Frame->Arguments[ArgIndex]; Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); if (ArgIndex == 0 && IsMemberCall) Out << "->" << *Frame->Callee << '('; } Out << ')'; } /// Evaluate an expression to see if it had side-effects, and discard its /// result. /// \return \c true if the caller should keep evaluating. static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { APValue Scratch; if (!Evaluate(Scratch, Info, E)) // We don't need the value, but we might have skipped a side effect here. return Info.noteSideEffect(); return true; } /// Sign- or zero-extend a value to 64 bits. If it's already 64 bits, just /// return its existing value. static int64_t getExtValue(const APSInt &Value) { return Value.isSigned() ? Value.getSExtValue() : static_cast<int64_t>(Value.getZExtValue()); } /// Should this call expression be treated as a string literal? static bool IsStringLiteralCall(const CallExpr *E) { unsigned Builtin = E->getBuiltinCallee(); return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || Builtin == Builtin::BI__builtin___NSStringMakeConstantString); } static bool IsGlobalLValue(APValue::LValueBase B) { // C++11 [expr.const]p3 An address constant expression is a prvalue core // constant expression of pointer type that evaluates to... // ... a null pointer value, or a prvalue core constant expression of type // std::nullptr_t. if (!B) return true; if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { // ... the address of an object with static storage duration, if (const VarDecl *VD = dyn_cast<VarDecl>(D)) return VD->hasGlobalStorage(); // ... the address of a function, return isa<FunctionDecl>(D); } const Expr *E = B.get<const Expr*>(); switch (E->getStmtClass()) { default: return false; case Expr::CompoundLiteralExprClass: { const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); return CLE->isFileScope() && CLE->isLValue(); } case Expr::MaterializeTemporaryExprClass: // A materialized temporary might have been lifetime-extended to static // storage duration. return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static; // A string literal has static storage duration. case Expr::StringLiteralClass: case Expr::PredefinedExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCEncodeExprClass: case Expr::CXXTypeidExprClass: case Expr::CXXUuidofExprClass: return true; case Expr::CallExprClass: return IsStringLiteralCall(cast<CallExpr>(E)); // For GCC compatibility, &&label has static storage duration. case Expr::AddrLabelExprClass: return true; // A Block literal expression may be used as the initialization value for // Block variables at global or local static scope. case Expr::BlockExprClass: return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); case Expr::ImplicitValueInitExprClass: // FIXME: // We can never form an lvalue with an implicit value initialization as its // base through expression evaluation, so these only appear in one case: the // implicit variable declaration we invent when checking whether a constexpr // constructor can produce a constant expression. We must assume that such // an expression might be a global lvalue. return true; } } static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { assert(Base && "no location for a null lvalue"); const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); if (VD) Info.Note(VD->getLocation(), diag::note_declared_at); else Info.Note(Base.get<const Expr*>()->getExprLoc(), diag::note_constexpr_temporary_here); } /// Check that this reference or pointer core constant expression is a valid /// value for an address or reference constant expression. Return true if we /// can fold this expression, whether or not it's a constant expression. static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, QualType Type, const LValue &LVal) { bool IsReferenceType = Type->isReferenceType(); APValue::LValueBase Base = LVal.getLValueBase(); const SubobjectDesignator &Designator = LVal.getLValueDesignator(); // Check that the object is a global. Note that the fake 'this' object we // manufacture when checking potential constant expressions is conservatively // assumed to be global here. if (!IsGlobalLValue(Base)) { if (Info.getLangOpts().CPlusPlus11) { const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); Info.FFDiag(Loc, diag::note_constexpr_non_global, 1) << IsReferenceType << !Designator.Entries.empty() << !!VD << VD; NoteLValueLocation(Info, Base); } else { Info.FFDiag(Loc); } // Don't allow references to temporaries to escape. return false; } assert((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"); if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) { if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) { // Check if this is a thread-local variable. if (Var->getTLSKind()) return false; // A dllimport variable never acts like a constant. if (Var->hasAttr<DLLImportAttr>()) return false; } if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) { // __declspec(dllimport) must be handled very carefully: // We must never initialize an expression with the thunk in C++. // Doing otherwise would allow the same id-expression to yield // different addresses for the same function in different translation // units. However, this means that we must dynamically initialize the // expression with the contents of the import address table at runtime. // // The C language has no notion of ODR; furthermore, it has no notion of // dynamic initialization. This means that we are permitted to // perform initialization with the address of the thunk. if (Info.getLangOpts().CPlusPlus && FD->hasAttr<DLLImportAttr>()) return false; } } // Allow address constant expressions to be past-the-end pointers. This is // an extension: the standard requires them to point to an object. if (!IsReferenceType) return true; // A reference constant expression must refer to an object. if (!Base) { // FIXME: diagnostic Info.CCEDiag(Loc); return true; } // Does this refer one past the end of some object? if (!Designator.Invalid && Designator.isOnePastTheEnd()) { const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); Info.FFDiag(Loc, diag::note_constexpr_past_end, 1) << !Designator.Entries.empty() << !!VD << VD; NoteLValueLocation(Info, Base); } return true; } /// Check that this core constant expression is of literal type, and if not, /// produce an appropriate diagnostic. static bool CheckLiteralType(EvalInfo &Info, const Expr *E, const LValue *This = nullptr) { if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx)) return true; // C++1y: A constant initializer for an object o [...] may also invoke // constexpr constructors for o and its subobjects even if those objects // are of non-literal class types. if (Info.getLangOpts().CPlusPlus14 && This && Info.EvaluatingDecl == This->getLValueBase()) return true; // Prvalue constant expressions must be of literal types. if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType(); else Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } /// Check that this core constant expression value is a valid value for a /// constant expression. If not, report an appropriate diagnostic. Does not /// check that the expression is of literal type. static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type, const APValue &Value) { if (Value.isUninit()) { Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) << true << Type; return false; } // We allow _Atomic(T) to be initialized from anything that T can be // initialized from. if (const AtomicType *AT = Type->getAs<AtomicType>()) Type = AT->getValueType(); // Core issue 1454: For a literal constant expression of array or class type, // each subobject of its value shall have been initialized by a constant // expression. if (Value.isArray()) { QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { if (!CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayInitializedElt(I))) return false; } if (!Value.hasArrayFiller()) return true; return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller()); } if (Value.isUnion() && Value.getUnionField()) { return CheckConstantExpression(Info, DiagLoc, Value.getUnionField()->getType(), Value.getUnionValue()); } if (Value.isStruct()) { RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { unsigned BaseIndex = 0; for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), End = CD->bases_end(); I != End; ++I, ++BaseIndex) { if (!CheckConstantExpression(Info, DiagLoc, I->getType(), Value.getStructBase(BaseIndex))) return false; } } for (const auto *I : RD->fields()) { if (!CheckConstantExpression(Info, DiagLoc, I->getType(), Value.getStructField(I->getFieldIndex()))) return false; } } if (Value.isLValue()) { LValue LVal; LVal.setFrom(Info.Ctx, Value); return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal); } // Everything else is fine. return true; } static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { return LVal.Base.dyn_cast<const ValueDecl*>(); } static bool IsLiteralLValue(const LValue &Value) { if (Value.CallIndex) return false; const Expr *E = Value.Base.dyn_cast<const Expr*>(); return E && !isa<MaterializeTemporaryExpr>(E); } static bool IsWeakLValue(const LValue &Value) { const ValueDecl *Decl = GetLValueBaseDecl(Value); return Decl && Decl->isWeak(); } static bool isZeroSized(const LValue &Value) { const ValueDecl *Decl = GetLValueBaseDecl(Value); if (Decl && isa<VarDecl>(Decl)) { QualType Ty = Decl->getType(); if (Ty->isArrayType()) return Ty->isIncompleteType() || Decl->getASTContext().getTypeSize(Ty) == 0; } return false; } static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { // A null base expression indicates a null pointer. These are always // evaluatable, and they are false unless the offset is zero. if (!Value.getLValueBase()) { Result = !Value.getLValueOffset().isZero(); return true; } // We have a non-null base. These are generally known to be true, but if it's // a weak declaration it can be null at runtime. Result = true; const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); return !Decl || !Decl->isWeak(); } static bool HandleConversionToBool(const APValue &Val, bool &Result) { switch (Val.getKind()) { case APValue::Uninitialized: return false; case APValue::Int: Result = Val.getInt().getBoolValue(); return true; case APValue::Float: Result = !Val.getFloat().isZero(); return true; case APValue::ComplexInt: Result = Val.getComplexIntReal().getBoolValue() || Val.getComplexIntImag().getBoolValue(); return true; case APValue::ComplexFloat: Result = !Val.getComplexFloatReal().isZero() || !Val.getComplexFloatImag().isZero(); return true; case APValue::LValue: return EvalPointerValueAsBool(Val, Result); case APValue::MemberPointer: Result = Val.getMemberPointerDecl(); return true; case APValue::Vector: case APValue::Array: case APValue::Struct: case APValue::Union: case APValue::AddrLabelDiff: return false; } llvm_unreachable("unknown APValue kind"); } static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, EvalInfo &Info) { assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"); APValue Val; if (!Evaluate(Val, Info, E)) return false; return HandleConversionToBool(Val, Result); } template<typename T> static bool HandleOverflow(EvalInfo &Info, const Expr *E, const T &SrcValue, QualType DestType) { Info.CCEDiag(E, diag::note_constexpr_overflow) << SrcValue << DestType; return Info.noteUndefinedBehavior(); } static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, QualType SrcType, const APFloat &Value, QualType DestType, APSInt &Result) { unsigned DestWidth = Info.Ctx.getIntWidth(DestType); // Determine whether we are converting to unsigned or signed. bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); Result = APSInt(DestWidth, !DestSigned); bool ignored; if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) & APFloat::opInvalidOp) return HandleOverflow(Info, E, Value, DestType); return true; } static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, QualType SrcType, QualType DestType, APFloat &Result) { APFloat Value = Result; bool ignored; if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), APFloat::rmNearestTiesToEven, &ignored) & APFloat::opOverflow) return HandleOverflow(Info, E, Value, DestType); return true; } static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, QualType DestType, QualType SrcType, const APSInt &Value) { unsigned DestWidth = Info.Ctx.getIntWidth(DestType); APSInt Result = Value; // Figure out if this is a truncate, extend or noop cast. // If the input is signed, do a sign extend, noop, or truncate. Result = Result.extOrTrunc(DestWidth); Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); return Result; } static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, QualType SrcType, const APSInt &Value, QualType DestType, APFloat &Result) { Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); if (Result.convertFromAPInt(Value, Value.isSigned(), APFloat::rmNearestTiesToEven) & APFloat::opOverflow) return HandleOverflow(Info, E, Value, DestType); return true; } static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, APValue &Value, const FieldDecl *FD) { assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield"); if (!Value.isInt()) { // Trying to store a pointer-cast-to-integer into a bitfield. // FIXME: In this case, we should provide the diagnostic for casting // a pointer to an integer. assert(Value.isLValue() && "integral value neither int nor lvalue?"); Info.FFDiag(E); return false; } APSInt &Int = Value.getInt(); unsigned OldBitWidth = Int.getBitWidth(); unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); if (NewBitWidth < OldBitWidth) Int = Int.trunc(NewBitWidth).extend(OldBitWidth); return true; } static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, llvm::APInt &Res) { APValue SVal; if (!Evaluate(SVal, Info, E)) return false; if (SVal.isInt()) { Res = SVal.getInt(); return true; } if (SVal.isFloat()) { Res = SVal.getFloat().bitcastToAPInt(); return true; } if (SVal.isVector()) { QualType VecTy = E->getType(); unsigned VecSize = Info.Ctx.getTypeSize(VecTy); QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); unsigned EltSize = Info.Ctx.getTypeSize(EltTy); bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); Res = llvm::APInt::getNullValue(VecSize); for (unsigned i = 0; i < SVal.getVectorLength(); i++) { APValue &Elt = SVal.getVectorElt(i); llvm::APInt EltAsInt; if (Elt.isInt()) { EltAsInt = Elt.getInt(); } else if (Elt.isFloat()) { EltAsInt = Elt.getFloat().bitcastToAPInt(); } else { // Don't try to handle vectors of anything other than int or float // (not sure if it's possible to hit this case). Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } unsigned BaseEltSize = EltAsInt.getBitWidth(); if (BigEndian) Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); else Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); } return true; } // Give up if the input isn't an int, float, or vector. For example, we // reject "(v4i16)(intptr_t)&a". Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } /// Perform the given integer operation, which is known to need at most BitWidth /// bits, and check for overflow in the original type (if that type was not an /// unsigned type). template<typename Operation> static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E, const APSInt &LHS, const APSInt &RHS, unsigned BitWidth, Operation Op, APSInt &Result) { if (LHS.isUnsigned()) { Result = Op(LHS, RHS); return true; } APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); Result = Value.trunc(LHS.getBitWidth()); if (Result.extend(BitWidth) != Value) { if (Info.checkingForOverflow()) Info.Ctx.getDiagnostics().Report(E->getExprLoc(), diag::warn_integer_constant_overflow) << Result.toString(10) << E->getType(); else return HandleOverflow(Info, E, Value, E->getType()); } return true; } /// Perform the given binary integer operation. static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, BinaryOperatorKind Opcode, APSInt RHS, APSInt &Result) { switch (Opcode) { default: Info.FFDiag(E); return false; case BO_Mul: return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, std::multiplies<APSInt>(), Result); case BO_Add: return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, std::plus<APSInt>(), Result); case BO_Sub: return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, std::minus<APSInt>(), Result); case BO_And: Result = LHS & RHS; return true; case BO_Xor: Result = LHS ^ RHS; return true; case BO_Or: Result = LHS | RHS; return true; case BO_Div: case BO_Rem: if (RHS == 0) { Info.FFDiag(E, diag::note_expr_divide_by_zero); return false; } Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports // this operation and gives the two's complement result. if (RHS.isNegative() && RHS.isAllOnesValue() && LHS.isSigned() && LHS.isMinSignedValue()) return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); return true; case BO_Shl: { if (Info.getLangOpts().OpenCL) // OpenCL 6.3j: shift values are effectively % word size of LHS. RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), static_cast<uint64_t>(LHS.getBitWidth() - 1)), RHS.isUnsigned()); else if (RHS.isSigned() && RHS.isNegative()) { // During constant-folding, a negative shift is an opposite shift. Such // a shift is not a constant expression. Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; RHS = -RHS; goto shift_right; } shift_left: // C++11 [expr.shift]p1: Shift width must be less than the bit width of // the shifted type. unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); if (SA != RHS) { Info.CCEDiag(E, diag::note_constexpr_large_shift) << RHS << E->getType() << LHS.getBitWidth(); } else if (LHS.isSigned()) { // C++11 [expr.shift]p2: A signed left shift must have a non-negative // operand, and must not overflow the corresponding unsigned type. if (LHS.isNegative()) Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; else if (LHS.countLeadingZeros() < SA) Info.CCEDiag(E, diag::note_constexpr_lshift_discards); } Result = LHS << SA; return true; } case BO_Shr: { if (Info.getLangOpts().OpenCL) // OpenCL 6.3j: shift values are effectively % word size of LHS. RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), static_cast<uint64_t>(LHS.getBitWidth() - 1)), RHS.isUnsigned()); else if (RHS.isSigned() && RHS.isNegative()) { // During constant-folding, a negative shift is an opposite shift. Such a // shift is not a constant expression. Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; RHS = -RHS; goto shift_left; } shift_right: // C++11 [expr.shift]p1: Shift width must be less than the bit width of the // shifted type. unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); if (SA != RHS) Info.CCEDiag(E, diag::note_constexpr_large_shift) << RHS << E->getType() << LHS.getBitWidth(); Result = LHS >> SA; return true; } case BO_LT: Result = LHS < RHS; return true; case BO_GT: Result = LHS > RHS; return true; case BO_LE: Result = LHS <= RHS; return true; case BO_GE: Result = LHS >= RHS; return true; case BO_EQ: Result = LHS == RHS; return true; case BO_NE: Result = LHS != RHS; return true; } } /// Perform the given binary floating-point operation, in-place, on LHS. static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E, APFloat &LHS, BinaryOperatorKind Opcode, const APFloat &RHS) { switch (Opcode) { default: Info.FFDiag(E); return false; case BO_Mul: LHS.multiply(RHS, APFloat::rmNearestTiesToEven); break; case BO_Add: LHS.add(RHS, APFloat::rmNearestTiesToEven); break; case BO_Sub: LHS.subtract(RHS, APFloat::rmNearestTiesToEven); break; case BO_Div: LHS.divide(RHS, APFloat::rmNearestTiesToEven); break; } if (LHS.isInfinity() || LHS.isNaN()) { Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); return Info.noteUndefinedBehavior(); } return true; } /// Cast an lvalue referring to a base subobject to a derived class, by /// truncating the lvalue's path to the given length. static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, const RecordDecl *TruncatedType, unsigned TruncatedElements) { SubobjectDesignator &D = Result.Designator; // Check we actually point to a derived class object. if (TruncatedElements == D.Entries.size()) return true; assert(TruncatedElements >= D.MostDerivedPathLength && "not casting to a derived class"); if (!Result.checkSubobject(Info, E, CSK_Derived)) return false; // Truncate the path to the subobject, and remove any derived-to-base offsets. const RecordDecl *RD = TruncatedType; for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); if (isVirtualBaseClass(D.Entries[I])) Result.Offset -= Layout.getVBaseClassOffset(Base); else Result.Offset -= Layout.getBaseClassOffset(Base); RD = Base; } D.Entries.resize(TruncatedElements); return true; } static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, const CXXRecordDecl *Derived, const CXXRecordDecl *Base, const ASTRecordLayout *RL = nullptr) { if (!RL) { if (Derived->isInvalidDecl()) return false; RL = &Info.Ctx.getASTRecordLayout(Derived); } Obj.getLValueOffset() += RL->getBaseClassOffset(Base); Obj.addDecl(Info, E, Base, /*Virtual*/ false); return true; } static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, const CXXRecordDecl *DerivedDecl, const CXXBaseSpecifier *Base) { const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); if (!Base->isVirtual()) return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); SubobjectDesignator &D = Obj.Designator; if (D.Invalid) return false; // Extract most-derived object and corresponding type. DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) return false; // Find the virtual base class. if (DerivedDecl->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); return true; } static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, QualType Type, LValue &Result) { for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), *PathI)) return false; Type = (*PathI)->getType(); } return true; } /// Update LVal to refer to the given field, which must be a member of the type /// currently described by LVal. static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, const FieldDecl *FD, const ASTRecordLayout *RL = nullptr) { if (!RL) { if (FD->getParent()->isInvalidDecl()) return false; RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); } unsigned I = FD->getFieldIndex(); LVal.Offset += Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)); LVal.addDecl(Info, E, FD); return true; } /// Update LVal to refer to the given indirect field. static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, LValue &LVal, const IndirectFieldDecl *IFD) { for (const auto *C : IFD->chain()) if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C))) return false; return true; } /// Get the size of the given type in char units. static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, QualType Type, CharUnits &Size) { // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc // extension. if (Type->isVoidType() || Type->isFunctionType()) { Size = CharUnits::One(); return true; } if (Type->isDependentType()) { Info.FFDiag(Loc); return false; } if (!Type->isConstantSizeType()) { // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. // FIXME: Better diagnostic. Info.FFDiag(Loc); return false; } Size = Info.Ctx.getTypeSizeInChars(Type); return true; } /// Update a pointer value to model pointer arithmetic. /// \param Info - Information about the ongoing evaluation. /// \param E - The expression being evaluated, for diagnostic purposes. /// \param LVal - The pointer value to be updated. /// \param EltTy - The pointee type represented by LVal. /// \param Adjustment - The adjustment, in objects of type EltTy, to add. static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, LValue &LVal, QualType EltTy, int64_t Adjustment) { CharUnits SizeOfPointee; if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) return false; // Compute the new offset in the appropriate width. LVal.Offset += Adjustment * SizeOfPointee; LVal.adjustIndex(Info, E, Adjustment); return true; } /// Update an lvalue to refer to a component of a complex number. /// \param Info - Information about the ongoing evaluation. /// \param LVal - The lvalue to be updated. /// \param EltTy - The complex number's component type. /// \param Imag - False for the real component, true for the imaginary. static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, LValue &LVal, QualType EltTy, bool Imag) { if (Imag) { CharUnits SizeOfComponent; if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) return false; LVal.Offset += SizeOfComponent; } LVal.addComplex(Info, E, EltTy, Imag); return true; } /// Try to evaluate the initializer for a variable declaration. /// /// \param Info Information about the ongoing evaluation. /// \param E An expression to be used when printing diagnostics. /// \param VD The variable whose initializer should be obtained. /// \param Frame The frame in which the variable was created. Must be null /// if this variable is not local to the evaluation. /// \param Result Filled in with a pointer to the value of the variable. static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, const VarDecl *VD, CallStackFrame *Frame, APValue *&Result) { // If this is a parameter to an active constexpr function call, perform // argument substitution. if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) { // Assume arguments of a potential constant expression are unknown // constant expressions. if (Info.checkingPotentialConstantExpression()) return false; if (!Frame || !Frame->Arguments) { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } Result = &Frame->Arguments[PVD->getFunctionScopeIndex()]; return true; } // If this is a local variable, dig out its value. if (Frame) { Result = Frame->getTemporary(VD); if (!Result) { // Assume variables referenced within a lambda's call operator that were // not declared within the call operator are captures and during checking // of a potential constant expression, assume they are unknown constant // expressions. assert(isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"); if (Info.checkingPotentialConstantExpression()) return false; // FIXME: implement capture evaluation during constant expr evaluation. Info.FFDiag(E->getLocStart(), diag::note_unimplemented_constexpr_lambda_feature_ast) << "captures not currently allowed"; return false; } return true; } // Dig out the initializer, and use the declaration which it's attached to. const Expr *Init = VD->getAnyInitializer(VD); if (!Init || Init->isValueDependent()) { // If we're checking a potential constant expression, the variable could be // initialized later. if (!Info.checkingPotentialConstantExpression()) Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } // If we're currently evaluating the initializer of this declaration, use that // in-flight value. if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) { Result = Info.EvaluatingDeclValue; return true; } // Never evaluate the initializer of a weak variable. We can't be sure that // this is the definition which will be used. if (VD->isWeak()) { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } // Check that we can fold the initializer. In C++, we will have already done // this in the cases where it matters for conformance. SmallVector<PartialDiagnosticAt, 8> Notes; if (!VD->evaluateValue(Notes)) { Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, Notes.size() + 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); Info.addNotes(Notes); return false; } else if (!VD->checkInitIsICE()) { Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, Notes.size() + 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); Info.addNotes(Notes); } Result = VD->getEvaluatedValue(); return true; } static bool IsConstNonVolatile(QualType T) { Qualifiers Quals = T.getQualifiers(); return Quals.hasConst() && !Quals.hasVolatile(); } /// Get the base index of the given base class within an APValue representing /// the given derived class. static unsigned getBaseIndex(const CXXRecordDecl *Derived, const CXXRecordDecl *Base) { Base = Base->getCanonicalDecl(); unsigned Index = 0; for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), E = Derived->bases_end(); I != E; ++I, ++Index) { if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) return Index; } llvm_unreachable("base class missing from derived class's bases list"); } /// Extract the value of a character from a string literal. static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, uint64_t Index) { // FIXME: Support ObjCEncodeExpr, MakeStringConstant if (auto PE = dyn_cast<PredefinedExpr>(Lit)) Lit = PE->getFunctionName(); const StringLiteral *S = cast<StringLiteral>(Lit); const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(S->getType()); assert(CAT && "string literal isn't an array"); QualType CharType = CAT->getElementType(); assert(CharType->isIntegerType() && "unexpected character type"); APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), CharType->isUnsignedIntegerType()); if (Index < S->getLength()) Value = S->getCodeUnit(Index); return Value; } // Expand a string literal into an array of characters. static void expandStringLiteral(EvalInfo &Info, const Expr *Lit, APValue &Result) { const StringLiteral *S = cast<StringLiteral>(Lit); const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(S->getType()); assert(CAT && "string literal isn't an array"); QualType CharType = CAT->getElementType(); assert(CharType->isIntegerType() && "unexpected character type"); unsigned Elts = CAT->getSize().getZExtValue(); Result = APValue(APValue::UninitArray(), std::min(S->getLength(), Elts), Elts); APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), CharType->isUnsignedIntegerType()); if (Result.hasArrayFiller()) Result.getArrayFiller() = APValue(Value); for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { Value = S->getCodeUnit(I); Result.getArrayInitializedElt(I) = APValue(Value); } } // Expand an array so that it has more than Index filled elements. static void expandArray(APValue &Array, unsigned Index) { unsigned Size = Array.getArraySize(); assert(Index < Size); // Always at least double the number of elements for which we store a value. unsigned OldElts = Array.getArrayInitializedElts(); unsigned NewElts = std::max(Index+1, OldElts * 2); NewElts = std::min(Size, std::max(NewElts, 8u)); // Copy the data across. APValue NewValue(APValue::UninitArray(), NewElts, Size); for (unsigned I = 0; I != OldElts; ++I) NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); for (unsigned I = OldElts; I != NewElts; ++I) NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); if (NewValue.hasArrayFiller()) NewValue.getArrayFiller() = Array.getArrayFiller(); Array.swap(NewValue); } /// Determine whether a type would actually be read by an lvalue-to-rvalue /// conversion. If it's of class type, we may assume that the copy operation /// is trivial. Note that this is never true for a union type with fields /// (because the copy always "reads" the active member) and always true for /// a non-class type. static bool isReadByLvalueToRvalueConversion(QualType T) { CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); if (!RD || (RD->isUnion() && !RD->field_empty())) return true; if (RD->isEmpty()) return false; for (auto *Field : RD->fields()) if (isReadByLvalueToRvalueConversion(Field->getType())) return true; for (auto &BaseSpec : RD->bases()) if (isReadByLvalueToRvalueConversion(BaseSpec.getType())) return true; return false; } /// Diagnose an attempt to read from any unreadable field within the specified /// type, which might be a class type. static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E, QualType T) { CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); if (!RD) return false; if (!RD->hasMutableFields()) return false; for (auto *Field : RD->fields()) { // If we're actually going to read this field in some way, then it can't // be mutable. If we're in a union, then assigning to a mutable field // (even an empty one) can change the active member, so that's not OK. // FIXME: Add core issue number for the union case. if (Field->isMutable() && (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) { Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field; Info.Note(Field->getLocation(), diag::note_declared_at); return true; } if (diagnoseUnreadableFields(Info, E, Field->getType())) return true; } for (auto &BaseSpec : RD->bases()) if (diagnoseUnreadableFields(Info, E, BaseSpec.getType())) return true; // All mutable fields were empty, and thus not actually read. return false; } /// Kinds of access we can perform on an object, for diagnostics. enum AccessKinds { AK_Read, AK_Assign, AK_Increment, AK_Decrement }; namespace { /// A handle to a complete object (an object that is not a subobject of /// another object). struct CompleteObject { /// The value of the complete object. APValue *Value; /// The type of the complete object. QualType Type; CompleteObject() : Value(nullptr) {} CompleteObject(APValue *Value, QualType Type) : Value(Value), Type(Type) { assert(Value && "missing value for complete object"); } explicit operator bool() const { return Value; } }; } // end anonymous namespace /// Find the designated sub-object of an rvalue. template<typename SubobjectHandler> typename SubobjectHandler::result_type findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, const SubobjectDesignator &Sub, SubobjectHandler &handler) { if (Sub.Invalid) // A diagnostic will have already been produced. return handler.failed(); if (Sub.isOnePastTheEnd()) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_access_past_end) << handler.AccessKind; else Info.FFDiag(E); return handler.failed(); } APValue *O = Obj.Value; QualType ObjType = Obj.Type; const FieldDecl *LastField = nullptr; // Walk the designator's path to find the subobject. for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { if (O->isUninit()) { if (!Info.checkingPotentialConstantExpression()) Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind; return handler.failed(); } if (I == N) { // If we are reading an object of class type, there may still be more // things we need to check: if there are any mutable subobjects, we // cannot perform this read. (This only happens when performing a trivial // copy or assignment.) if (ObjType->isRecordType() && handler.AccessKind == AK_Read && diagnoseUnreadableFields(Info, E, ObjType)) return handler.failed(); if (!handler.found(*O, ObjType)) return false; // If we modified a bit-field, truncate it to the right width. if (handler.AccessKind != AK_Read && LastField && LastField->isBitField() && !truncateBitfieldValue(Info, E, *O, LastField)) return false; return true; } LastField = nullptr; if (ObjType->isArrayType()) { // Next subobject is an array element. const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); assert(CAT && "vla in literal type?"); uint64_t Index = Sub.Entries[I].ArrayIndex; if (CAT->getSize().ule(Index)) { // Note, it should not be possible to form a pointer with a valid // designator which points more than one past the end of the array. if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_access_past_end) << handler.AccessKind; else Info.FFDiag(E); return handler.failed(); } ObjType = CAT->getElementType(); // An array object is represented as either an Array APValue or as an // LValue which refers to a string literal. if (O->isLValue()) { assert(I == N - 1 && "extracting subobject of character?"); assert(!O->hasLValuePath() || O->getLValuePath().empty()); if (handler.AccessKind != AK_Read) expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(), *O); else return handler.foundString(*O, ObjType, Index); } if (O->getArrayInitializedElts() > Index) O = &O->getArrayInitializedElt(Index); else if (handler.AccessKind != AK_Read) { expandArray(*O, Index); O = &O->getArrayInitializedElt(Index); } else O = &O->getArrayFiller(); } else if (ObjType->isAnyComplexType()) { // Next subobject is a complex number. uint64_t Index = Sub.Entries[I].ArrayIndex; if (Index > 1) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_access_past_end) << handler.AccessKind; else Info.FFDiag(E); return handler.failed(); } bool WasConstQualified = ObjType.isConstQualified(); ObjType = ObjType->castAs<ComplexType>()->getElementType(); if (WasConstQualified) ObjType.addConst(); assert(I == N - 1 && "extracting subobject of scalar?"); if (O->isComplexInt()) { return handler.found(Index ? O->getComplexIntImag() : O->getComplexIntReal(), ObjType); } else { assert(O->isComplexFloat()); return handler.found(Index ? O->getComplexFloatImag() : O->getComplexFloatReal(), ObjType); } } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { if (Field->isMutable() && handler.AccessKind == AK_Read) { Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field; Info.Note(Field->getLocation(), diag::note_declared_at); return handler.failed(); } // Next subobject is a class, struct or union field. RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); if (RD->isUnion()) { const FieldDecl *UnionField = O->getUnionField(); if (!UnionField || UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member) << handler.AccessKind << Field << !UnionField << UnionField; return handler.failed(); } O = &O->getUnionValue(); } else O = &O->getStructField(Field->getFieldIndex()); bool WasConstQualified = ObjType.isConstQualified(); ObjType = Field->getType(); if (WasConstQualified && !Field->isMutable()) ObjType.addConst(); if (ObjType.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) { // FIXME: Include a description of the path to the volatile subobject. Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) << handler.AccessKind << 2 << Field; Info.Note(Field->getLocation(), diag::note_declared_at); } else { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); } return handler.failed(); } LastField = Field; } else { // Next subobject is a base class. const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); O = &O->getStructBase(getBaseIndex(Derived, Base)); bool WasConstQualified = ObjType.isConstQualified(); ObjType = Info.Ctx.getRecordType(Base); if (WasConstQualified) ObjType.addConst(); } } } namespace { struct ExtractSubobjectHandler { EvalInfo &Info; APValue &Result; static const AccessKinds AccessKind = AK_Read; typedef bool result_type; bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { Result = Subobj; return true; } bool found(APSInt &Value, QualType SubobjType) { Result = APValue(Value); return true; } bool found(APFloat &Value, QualType SubobjType) { Result = APValue(Value); return true; } bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { Result = APValue(extractStringLiteralCharacter( Info, Subobj.getLValueBase().get<const Expr *>(), Character)); return true; } }; } // end anonymous namespace const AccessKinds ExtractSubobjectHandler::AccessKind; /// Extract the designated sub-object of an rvalue. static bool extractSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, const SubobjectDesignator &Sub, APValue &Result) { ExtractSubobjectHandler Handler = { Info, Result }; return findSubobject(Info, E, Obj, Sub, Handler); } namespace { struct ModifySubobjectHandler { EvalInfo &Info; APValue &NewVal; const Expr *E; typedef bool result_type; static const AccessKinds AccessKind = AK_Assign; bool checkConst(QualType QT) { // Assigning to a const object has undefined behavior. if (QT.isConstQualified()) { Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; return false; } return true; } bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) return false; // We've been given ownership of NewVal, so just swap it in. Subobj.swap(NewVal); return true; } bool found(APSInt &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (!NewVal.isInt()) { // Maybe trying to write a cast pointer value into a complex? Info.FFDiag(E); return false; } Value = NewVal.getInt(); return true; } bool found(APFloat &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; Value = NewVal.getFloat(); return true; } bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { llvm_unreachable("shouldn't encounter string elements with ExpandArrays"); } }; } // end anonymous namespace const AccessKinds ModifySubobjectHandler::AccessKind; /// Update the designated sub-object of an rvalue to the given value. static bool modifySubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, const SubobjectDesignator &Sub, APValue &NewVal) { ModifySubobjectHandler Handler = { Info, NewVal, E }; return findSubobject(Info, E, Obj, Sub, Handler); } /// Find the position where two subobject designators diverge, or equivalently /// the length of the common initial subsequence. static unsigned FindDesignatorMismatch(QualType ObjType, const SubobjectDesignator &A, const SubobjectDesignator &B, bool &WasArrayIndex) { unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); for (/**/; I != N; ++I) { if (!ObjType.isNull() && (ObjType->isArrayType() || ObjType->isAnyComplexType())) { // Next subobject is an array element. if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) { WasArrayIndex = true; return I; } if (ObjType->isAnyComplexType()) ObjType = ObjType->castAs<ComplexType>()->getElementType(); else ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); } else { if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) { WasArrayIndex = false; return I; } if (const FieldDecl *FD = getAsField(A.Entries[I])) // Next subobject is a field. ObjType = FD->getType(); else // Next subobject is a base class. ObjType = QualType(); } } WasArrayIndex = false; return I; } /// Determine whether the given subobject designators refer to elements of the /// same array object. static bool AreElementsOfSameArray(QualType ObjType, const SubobjectDesignator &A, const SubobjectDesignator &B) { if (A.Entries.size() != B.Entries.size()) return false; bool IsArray = A.MostDerivedIsArrayElement; if (IsArray && A.MostDerivedPathLength != A.Entries.size()) // A is a subobject of the array element. return false; // If A (and B) designates an array element, the last entry will be the array // index. That doesn't have to match. Otherwise, we're in the 'implicit array // of length 1' case, and the entire path must match. bool WasArrayIndex; unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); return CommonLength >= A.Entries.size() - IsArray; } /// Find the complete object to which an LValue refers. static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, AccessKinds AK, const LValue &LVal, QualType LValType) { if (!LVal.Base) { Info.FFDiag(E, diag::note_constexpr_access_null) << AK; return CompleteObject(); } CallStackFrame *Frame = nullptr; if (LVal.CallIndex) { Frame = Info.getCallFrame(LVal.CallIndex); if (!Frame) { Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1) << AK << LVal.Base.is<const ValueDecl*>(); NoteLValueLocation(Info, LVal.Base); return CompleteObject(); } } // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type // is not a constant expression (even if the object is non-volatile). We also // apply this rule to C++98, in order to conform to the expected 'volatile' // semantics. if (LValType.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) Info.FFDiag(E, diag::note_constexpr_access_volatile_type) << AK << LValType; else Info.FFDiag(E); return CompleteObject(); } // Compute value storage location and type of base object. APValue *BaseVal = nullptr; QualType BaseType = getType(LVal.Base); if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) { // In C++98, const, non-volatile integers initialized with ICEs are ICEs. // In C++11, constexpr, non-volatile variables initialized with constant // expressions are constant expressions too. Inside constexpr functions, // parameters are constant expressions even if they're non-const. // In C++1y, objects local to a constant expression (those with a Frame) are // both readable and writable inside constant expressions. // In C, such things can also be folded, although they are not ICEs. const VarDecl *VD = dyn_cast<VarDecl>(D); if (VD) { if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) VD = VDef; } if (!VD || VD->isInvalidDecl()) { Info.FFDiag(E); return CompleteObject(); } // Accesses of volatile-qualified objects are not allowed. if (BaseType.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) { Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) << AK << 1 << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.FFDiag(E); } return CompleteObject(); } // Unless we're looking at a local variable or argument in a constexpr call, // the variable we're reading must be const. if (!Frame) { if (Info.getLangOpts().CPlusPlus14 && VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) { // OK, we can read and modify an object if we're in the process of // evaluating its initializer, because its lifetime began in this // evaluation. } else if (AK != AK_Read) { // All the remaining cases only permit reading. Info.FFDiag(E, diag::note_constexpr_modify_global); return CompleteObject(); } else if (VD->isConstexpr()) { // OK, we can read this variable. } else if (BaseType->isIntegralOrEnumerationType()) { // In OpenCL if a variable is in constant address space it is a const value. if (!(BaseType.isConstQualified() || (Info.getLangOpts().OpenCL && BaseType.getAddressSpace() == LangAS::opencl_constant))) { if (Info.getLangOpts().CPlusPlus) { Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.FFDiag(E); } return CompleteObject(); } } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) { // We support folding of const floating-point types, in order to make // static const data members of such types (supported as an extension) // more useful. if (Info.getLangOpts().CPlusPlus11) { Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.CCEDiag(E); } } else { // FIXME: Allow folding of values of any literal type in all languages. if (Info.checkingPotentialConstantExpression() && VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) { // The definition of this variable could be constexpr. We can't // access it right now, but may be able to in future. } else if (Info.getLangOpts().CPlusPlus11) { Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; Info.Note(VD->getLocation(), diag::note_declared_at); } else { Info.FFDiag(E); } return CompleteObject(); } } if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal)) return CompleteObject(); } else { const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); if (!Frame) { if (const MaterializeTemporaryExpr *MTE = dyn_cast<MaterializeTemporaryExpr>(Base)) { assert(MTE->getStorageDuration() == SD_Static && "should have a frame for a non-global materialized temporary"); // Per C++1y [expr.const]p2: // an lvalue-to-rvalue conversion [is not allowed unless it applies to] // - a [...] glvalue of integral or enumeration type that refers to // a non-volatile const object [...] // [...] // - a [...] glvalue of literal type that refers to a non-volatile // object whose lifetime began within the evaluation of e. // // C++11 misses the 'began within the evaluation of e' check and // instead allows all temporaries, including things like: // int &&r = 1; // int x = ++r; // constexpr int k = r; // Therefore we use the C++1y rules in C++11 too. const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>(); const ValueDecl *ED = MTE->getExtendingDecl(); if (!(BaseType.isConstQualified() && BaseType->isIntegralOrEnumerationType()) && !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) { Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK; Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); return CompleteObject(); } BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false); assert(BaseVal && "got reference to unevaluated temporary"); } else { Info.FFDiag(E); return CompleteObject(); } } else { BaseVal = Frame->getTemporary(Base); assert(BaseVal && "missing value for temporary"); } // Volatile temporary objects cannot be accessed in constant expressions. if (BaseType.isVolatileQualified()) { if (Info.getLangOpts().CPlusPlus) { Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) << AK << 0; Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here); } else { Info.FFDiag(E); } return CompleteObject(); } } // During the construction of an object, it is not yet 'const'. // FIXME: We don't set up EvaluatingDecl for local variables or temporaries, // and this doesn't do quite the right thing for const subobjects of the // object under construction. if (LVal.getLValueBase() == Info.EvaluatingDecl) { BaseType = Info.Ctx.getCanonicalType(BaseType); BaseType.removeLocalConst(); } // In C++1y, we can't safely access any mutable state when we might be // evaluating after an unmodeled side effect. // // FIXME: Not all local state is mutable. Allow local constant subobjects // to be read here (but take care with 'mutable' fields). if ((Frame && Info.getLangOpts().CPlusPlus14 && Info.EvalStatus.HasSideEffects) || (AK != AK_Read && Info.IsSpeculativelyEvaluating)) return CompleteObject(); return CompleteObject(BaseVal, BaseType); } /// \brief Perform an lvalue-to-rvalue conversion on the given glvalue. This /// can also be used for 'lvalue-to-lvalue' conversions for looking up the /// glvalue referred to by an entity of reference type. /// /// \param Info - Information about the ongoing evaluation. /// \param Conv - The expression for which we are performing the conversion. /// Used for diagnostics. /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the /// case of a non-class type). /// \param LVal - The glvalue on which we are attempting to perform this action. /// \param RVal - The produced value will be placed here. static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type, const LValue &LVal, APValue &RVal) { if (LVal.Designator.Invalid) return false; // Check for special cases where there is no existing APValue to look at. const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); if (Base && !LVal.CallIndex && !Type.isVolatileQualified()) { if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the // initializer until now for such expressions. Such an expression can't be // an ICE in C, so this only matters for fold. assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); if (Type.isVolatileQualified()) { Info.FFDiag(Conv); return false; } APValue Lit; if (!Evaluate(Lit, Info, CLE->getInitializer())) return false; CompleteObject LitObj(&Lit, Base->getType()); return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal); } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) { // We represent a string literal array as an lvalue pointing at the // corresponding expression, rather than building an array of chars. // FIXME: Support ObjCEncodeExpr, MakeStringConstant APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0); CompleteObject StrObj(&Str, Base->getType()); return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal); } } CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type); return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal); } /// Perform an assignment of Val to LVal. Takes ownership of Val. static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, QualType LValType, APValue &Val) { if (LVal.Designator.Invalid) return false; if (!Info.getLangOpts().CPlusPlus14) { Info.FFDiag(E); return false; } CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); } static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) { return T->isSignedIntegerType() && Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy); } namespace { struct CompoundAssignSubobjectHandler { EvalInfo &Info; const Expr *E; QualType PromotedLHSType; BinaryOperatorKind Opcode; const APValue &RHS; static const AccessKinds AccessKind = AK_Assign; typedef bool result_type; bool checkConst(QualType QT) { // Assigning to a const object has undefined behavior. if (QT.isConstQualified()) { Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; return false; } return true; } bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { switch (Subobj.getKind()) { case APValue::Int: return found(Subobj.getInt(), SubobjType); case APValue::Float: return found(Subobj.getFloat(), SubobjType); case APValue::ComplexInt: case APValue::ComplexFloat: // FIXME: Implement complex compound assignment. Info.FFDiag(E); return false; case APValue::LValue: return foundPointer(Subobj, SubobjType); default: // FIXME: can this happen? Info.FFDiag(E); return false; } } bool found(APSInt &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (!SubobjType->isIntegerType() || !RHS.isInt()) { // We don't support compound assignment on integer-cast-to-pointer // values. Info.FFDiag(E); return false; } APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value); if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) return false; Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); return true; } bool found(APFloat &Value, QualType SubobjType) { return checkConst(SubobjType) && HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, Value) && handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); } bool foundPointer(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) return false; QualType PointeeType; if (const PointerType *PT = SubobjType->getAs<PointerType>()) PointeeType = PT->getPointeeType(); if (PointeeType.isNull() || !RHS.isInt() || (Opcode != BO_Add && Opcode != BO_Sub)) { Info.FFDiag(E); return false; } int64_t Offset = getExtValue(RHS.getInt()); if (Opcode == BO_Sub) Offset = -Offset; LValue LVal; LVal.setFrom(Info.Ctx, Subobj); if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) return false; LVal.moveInto(Subobj); return true; } bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { llvm_unreachable("shouldn't encounter string elements here"); } }; } // end anonymous namespace const AccessKinds CompoundAssignSubobjectHandler::AccessKind; /// Perform a compound assignment of LVal <op>= RVal. static bool handleCompoundAssignment( EvalInfo &Info, const Expr *E, const LValue &LVal, QualType LValType, QualType PromotedLValType, BinaryOperatorKind Opcode, const APValue &RVal) { if (LVal.Designator.Invalid) return false; if (!Info.getLangOpts().CPlusPlus14) { Info.FFDiag(E); return false; } CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, RVal }; return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); } namespace { struct IncDecSubobjectHandler { EvalInfo &Info; const Expr *E; AccessKinds AccessKind; APValue *Old; typedef bool result_type; bool checkConst(QualType QT) { // Assigning to a const object has undefined behavior. if (QT.isConstQualified()) { Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; return false; } return true; } bool failed() { return false; } bool found(APValue &Subobj, QualType SubobjType) { // Stash the old value. Also clear Old, so we don't clobber it later // if we're post-incrementing a complex. if (Old) { *Old = Subobj; Old = nullptr; } switch (Subobj.getKind()) { case APValue::Int: return found(Subobj.getInt(), SubobjType); case APValue::Float: return found(Subobj.getFloat(), SubobjType); case APValue::ComplexInt: return found(Subobj.getComplexIntReal(), SubobjType->castAs<ComplexType>()->getElementType() .withCVRQualifiers(SubobjType.getCVRQualifiers())); case APValue::ComplexFloat: return found(Subobj.getComplexFloatReal(), SubobjType->castAs<ComplexType>()->getElementType() .withCVRQualifiers(SubobjType.getCVRQualifiers())); case APValue::LValue: return foundPointer(Subobj, SubobjType); default: // FIXME: can this happen? Info.FFDiag(E); return false; } } bool found(APSInt &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (!SubobjType->isIntegerType()) { // We don't support increment / decrement on integer-cast-to-pointer // values. Info.FFDiag(E); return false; } if (Old) *Old = APValue(Value); // bool arithmetic promotes to int, and the conversion back to bool // doesn't reduce mod 2^n, so special-case it. if (SubobjType->isBooleanType()) { if (AccessKind == AK_Increment) Value = 1; else Value = !Value; return true; } bool WasNegative = Value.isNegative(); if (AccessKind == AK_Increment) { ++Value; if (!WasNegative && Value.isNegative() && isOverflowingIntegerType(Info.Ctx, SubobjType)) { APSInt ActualValue(Value, /*IsUnsigned*/true); return HandleOverflow(Info, E, ActualValue, SubobjType); } } else { --Value; if (WasNegative && !Value.isNegative() && isOverflowingIntegerType(Info.Ctx, SubobjType)) { unsigned BitWidth = Value.getBitWidth(); APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); ActualValue.setBit(BitWidth); return HandleOverflow(Info, E, ActualValue, SubobjType); } } return true; } bool found(APFloat &Value, QualType SubobjType) { if (!checkConst(SubobjType)) return false; if (Old) *Old = APValue(Value); APFloat One(Value.getSemantics(), 1); if (AccessKind == AK_Increment) Value.add(One, APFloat::rmNearestTiesToEven); else Value.subtract(One, APFloat::rmNearestTiesToEven); return true; } bool foundPointer(APValue &Subobj, QualType SubobjType) { if (!checkConst(SubobjType)) return false; QualType PointeeType; if (const PointerType *PT = SubobjType->getAs<PointerType>()) PointeeType = PT->getPointeeType(); else { Info.FFDiag(E); return false; } LValue LVal; LVal.setFrom(Info.Ctx, Subobj); if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, AccessKind == AK_Increment ? 1 : -1)) return false; LVal.moveInto(Subobj); return true; } bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { llvm_unreachable("shouldn't encounter string elements here"); } }; } // end anonymous namespace /// Perform an increment or decrement on LVal. static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, QualType LValType, bool IsIncrement, APValue *Old) { if (LVal.Designator.Invalid) return false; if (!Info.getLangOpts().CPlusPlus14) { Info.FFDiag(E); return false; } AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); IncDecSubobjectHandler Handler = { Info, E, AK, Old }; return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); } /// Build an lvalue for the object argument of a member function call. static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, LValue &This) { if (Object->getType()->isPointerType()) return EvaluatePointer(Object, This, Info); if (Object->isGLValue()) return EvaluateLValue(Object, This, Info); if (Object->getType()->isLiteralType(Info.Ctx)) return EvaluateTemporary(Object, This, Info); Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType(); return false; } /// HandleMemberPointerAccess - Evaluate a member access operation and build an /// lvalue referring to the result. /// /// \param Info - Information about the ongoing evaluation. /// \param LV - An lvalue referring to the base of the member pointer. /// \param RHS - The member pointer expression. /// \param IncludeMember - Specifies whether the member itself is included in /// the resulting LValue subobject designator. This is not possible when /// creating a bound member function. /// \return The field or method declaration to which the member pointer refers, /// or 0 if evaluation fails. static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, QualType LVType, LValue &LV, const Expr *RHS, bool IncludeMember = true) { MemberPtr MemPtr; if (!EvaluateMemberPointer(RHS, MemPtr, Info)) return nullptr; // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to // member value, the behavior is undefined. if (!MemPtr.getDecl()) { // FIXME: Specific diagnostic. Info.FFDiag(RHS); return nullptr; } if (MemPtr.isDerivedMember()) { // This is a member of some derived class. Truncate LV appropriately. // The end of the derived-to-base path for the base object must match the // derived-to-base path for the member pointer. if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > LV.Designator.Entries.size()) { Info.FFDiag(RHS); return nullptr; } unsigned PathLengthToMember = LV.Designator.Entries.size() - MemPtr.Path.size(); for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { const CXXRecordDecl *LVDecl = getAsBaseClass( LV.Designator.Entries[PathLengthToMember + I]); const CXXRecordDecl *MPDecl = MemPtr.Path[I]; if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { Info.FFDiag(RHS); return nullptr; } } // Truncate the lvalue to the appropriate derived class. if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), PathLengthToMember)) return nullptr; } else if (!MemPtr.Path.empty()) { // Extend the LValue path with the member pointer's path. LV.Designator.Entries.reserve(LV.Designator.Entries.size() + MemPtr.Path.size() + IncludeMember); // Walk down to the appropriate base class. if (const PointerType *PT = LVType->getAs<PointerType>()) LVType = PT->getPointeeType(); const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); assert(RD && "member pointer access on non-class-type expression"); // The first class in the path is that of the lvalue. for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) return nullptr; RD = Base; } // Finally cast to the class containing the member. if (!HandleLValueDirectBase(Info, RHS, LV, RD, MemPtr.getContainingRecord())) return nullptr; } // Add the member. Note that we cannot build bound member functions here. if (IncludeMember) { if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { if (!HandleLValueMember(Info, RHS, LV, FD)) return nullptr; } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) return nullptr; } else { llvm_unreachable("can't construct reference to bound member function"); } } return MemPtr.getDecl(); } static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, const BinaryOperator *BO, LValue &LV, bool IncludeMember = true) { assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { if (Info.noteFailure()) { MemberPtr MemPtr; EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); } return nullptr; } return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, BO->getRHS(), IncludeMember); } /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on /// the provided lvalue, which currently refers to the base object. static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, LValue &Result) { SubobjectDesignator &D = Result.Designator; if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) return false; QualType TargetQT = E->getType(); if (const PointerType *PT = TargetQT->getAs<PointerType>()) TargetQT = PT->getPointeeType(); // Check this cast lands within the final derived-to-base subobject path. if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) << D.MostDerivedType << TargetQT; return false; } // Check the type of the final cast. We don't need to check the path, // since a cast can only be formed if the path is unique. unsigned NewEntriesSize = D.Entries.size() - E->path_size(); const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); const CXXRecordDecl *FinalType; if (NewEntriesSize == D.MostDerivedPathLength) FinalType = D.MostDerivedType->getAsCXXRecordDecl(); else FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) << D.MostDerivedType << TargetQT; return false; } // Truncate the lvalue to the appropriate derived class. return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); } namespace { enum EvalStmtResult { /// Evaluation failed. ESR_Failed, /// Hit a 'return' statement. ESR_Returned, /// Evaluation succeeded. ESR_Succeeded, /// Hit a 'continue' statement. ESR_Continue, /// Hit a 'break' statement. ESR_Break, /// Still scanning for 'case' or 'default' statement. ESR_CaseNotFound }; } static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { // We don't need to evaluate the initializer for a static local. if (!VD->hasLocalStorage()) return true; LValue Result; Result.set(VD, Info.CurrentCall->Index); APValue &Val = Info.CurrentCall->createTemporary(VD, true); const Expr *InitE = VD->getInit(); if (!InitE) { Info.FFDiag(D->getLocStart(), diag::note_constexpr_uninitialized) << false << VD->getType(); Val = APValue(); return false; } if (InitE->isValueDependent()) return false; if (!EvaluateInPlace(Val, Info, Result, InitE)) { // Wipe out any partially-computed value, to allow tracking that this // evaluation failed. Val = APValue(); return false; } } return true; } /// Evaluate a condition (either a variable declaration or an expression). static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, const Expr *Cond, bool &Result) { FullExpressionRAII Scope(Info); if (CondDecl && !EvaluateDecl(Info, CondDecl)) return false; return EvaluateAsBooleanCondition(Cond, Result, Info); } namespace { /// \brief A location where the result (returned value) of evaluating a /// statement should be stored. struct StmtResult { /// The APValue that should be filled in with the returned value. APValue &Value; /// The location containing the result, if any (used to support RVO). const LValue *Slot; }; } static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, const Stmt *S, const SwitchCase *SC = nullptr); /// Evaluate the body of a loop, and translate the result as appropriate. static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info, const Stmt *Body, const SwitchCase *Case = nullptr) { BlockScopeRAII Scope(Info); switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) { case ESR_Break: return ESR_Succeeded; case ESR_Succeeded: case ESR_Continue: return ESR_Continue; case ESR_Failed: case ESR_Returned: case ESR_CaseNotFound: return ESR; } llvm_unreachable("Invalid EvalStmtResult!"); } /// Evaluate a switch statement. static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info, const SwitchStmt *SS) { BlockScopeRAII Scope(Info); // Evaluate the switch condition. APSInt Value; { FullExpressionRAII Scope(Info); if (const Stmt *Init = SS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); if (ESR != ESR_Succeeded) return ESR; } if (SS->getConditionVariable() && !EvaluateDecl(Info, SS->getConditionVariable())) return ESR_Failed; if (!EvaluateInteger(SS->getCond(), Value, Info)) return ESR_Failed; } // Find the switch case corresponding to the value of the condition. // FIXME: Cache this lookup. const SwitchCase *Found = nullptr; for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; SC = SC->getNextSwitchCase()) { if (isa<DefaultStmt>(SC)) { Found = SC; continue; } const CaseStmt *CS = cast<CaseStmt>(SC); APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) : LHS; if (LHS <= Value && Value <= RHS) { Found = SC; break; } } if (!Found) return ESR_Succeeded; // Search the switch body for the switch case and evaluate it from there. switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) { case ESR_Break: return ESR_Succeeded; case ESR_Succeeded: case ESR_Continue: case ESR_Failed: case ESR_Returned: return ESR; case ESR_CaseNotFound: // This can only happen if the switch case is nested within a statement // expression. We have no intention of supporting that. Info.FFDiag(Found->getLocStart(), diag::note_constexpr_stmt_expr_unsupported); return ESR_Failed; } llvm_unreachable("Invalid EvalStmtResult!"); } // Evaluate a statement. static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, const Stmt *S, const SwitchCase *Case) { if (!Info.nextStep(S)) return ESR_Failed; // If we're hunting down a 'case' or 'default' label, recurse through // substatements until we hit the label. if (Case) { // FIXME: We don't start the lifetime of objects whose initialization we // jump over. However, such objects must be of class type with a trivial // default constructor that initialize all subobjects, so must be empty, // so this almost never matters. switch (S->getStmtClass()) { case Stmt::CompoundStmtClass: // FIXME: Precompute which substatement of a compound statement we // would jump to, and go straight there rather than performing a // linear scan each time. case Stmt::LabelStmtClass: case Stmt::AttributedStmtClass: case Stmt::DoStmtClass: break; case Stmt::CaseStmtClass: case Stmt::DefaultStmtClass: if (Case == S) Case = nullptr; break; case Stmt::IfStmtClass: { // FIXME: Precompute which side of an 'if' we would jump to, and go // straight there rather than scanning both sides. const IfStmt *IS = cast<IfStmt>(S); // Wrap the evaluation in a block scope, in case it's a DeclStmt // preceded by our switch label. BlockScopeRAII Scope(Info); EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); if (ESR != ESR_CaseNotFound || !IS->getElse()) return ESR; return EvaluateStmt(Result, Info, IS->getElse(), Case); } case Stmt::WhileStmtClass: { EvalStmtResult ESR = EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); if (ESR != ESR_Continue) return ESR; break; } case Stmt::ForStmtClass: { const ForStmt *FS = cast<ForStmt>(S); EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody(), Case); if (ESR != ESR_Continue) return ESR; if (FS->getInc()) { FullExpressionRAII IncScope(Info); if (!EvaluateIgnoredValue(Info, FS->getInc())) return ESR_Failed; } break; } case Stmt::DeclStmtClass: // FIXME: If the variable has initialization that can't be jumped over, // bail out of any immediately-surrounding compound-statement too. default: return ESR_CaseNotFound; } } switch (S->getStmtClass()) { default: if (const Expr *E = dyn_cast<Expr>(S)) { // Don't bother evaluating beyond an expression-statement which couldn't // be evaluated. FullExpressionRAII Scope(Info); if (!EvaluateIgnoredValue(Info, E)) return ESR_Failed; return ESR_Succeeded; } Info.FFDiag(S->getLocStart()); return ESR_Failed; case Stmt::NullStmtClass: return ESR_Succeeded; case Stmt::DeclStmtClass: { const DeclStmt *DS = cast<DeclStmt>(S); for (const auto *DclIt : DS->decls()) { // Each declaration initialization is its own full-expression. // FIXME: This isn't quite right; if we're performing aggregate // initialization, each braced subexpression is its own full-expression. FullExpressionRAII Scope(Info); if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure()) return ESR_Failed; } return ESR_Succeeded; } case Stmt::ReturnStmtClass: { const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); FullExpressionRAII Scope(Info); if (RetExpr && !(Result.Slot ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr) : Evaluate(Result.Value, Info, RetExpr))) return ESR_Failed; return ESR_Returned; } case Stmt::CompoundStmtClass: { BlockScopeRAII Scope(Info); const CompoundStmt *CS = cast<CompoundStmt>(S); for (const auto *BI : CS->body()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); if (ESR == ESR_Succeeded) Case = nullptr; else if (ESR != ESR_CaseNotFound) return ESR; } return Case ? ESR_CaseNotFound : ESR_Succeeded; } case Stmt::IfStmtClass: { const IfStmt *IS = cast<IfStmt>(S); // Evaluate the condition, as either a var decl or as an expression. BlockScopeRAII Scope(Info); if (const Stmt *Init = IS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); if (ESR != ESR_Succeeded) return ESR; } bool Cond; if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) return ESR_Failed; if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); if (ESR != ESR_Succeeded) return ESR; } return ESR_Succeeded; } case Stmt::WhileStmtClass: { const WhileStmt *WS = cast<WhileStmt>(S); while (true) { BlockScopeRAII Scope(Info); bool Continue; if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), Continue)) return ESR_Failed; if (!Continue) break; EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); if (ESR != ESR_Continue) return ESR; } return ESR_Succeeded; } case Stmt::DoStmtClass: { const DoStmt *DS = cast<DoStmt>(S); bool Continue; do { EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); if (ESR != ESR_Continue) return ESR; Case = nullptr; FullExpressionRAII CondScope(Info); if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info)) return ESR_Failed; } while (Continue); return ESR_Succeeded; } case Stmt::ForStmtClass: { const ForStmt *FS = cast<ForStmt>(S); BlockScopeRAII Scope(Info); if (FS->getInit()) { EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); if (ESR != ESR_Succeeded) return ESR; } while (true) { BlockScopeRAII Scope(Info); bool Continue = true; if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), FS->getCond(), Continue)) return ESR_Failed; if (!Continue) break; EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); if (ESR != ESR_Continue) return ESR; if (FS->getInc()) { FullExpressionRAII IncScope(Info); if (!EvaluateIgnoredValue(Info, FS->getInc())) return ESR_Failed; } } return ESR_Succeeded; } case Stmt::CXXForRangeStmtClass: { const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); BlockScopeRAII Scope(Info); // Initialize the __range variable. EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); if (ESR != ESR_Succeeded) return ESR; // Create the __begin and __end iterators. ESR = EvaluateStmt(Result, Info, FS->getBeginStmt()); if (ESR != ESR_Succeeded) return ESR; ESR = EvaluateStmt(Result, Info, FS->getEndStmt()); if (ESR != ESR_Succeeded) return ESR; while (true) { // Condition: __begin != __end. { bool Continue = true; FullExpressionRAII CondExpr(Info); if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) return ESR_Failed; if (!Continue) break; } // User's variable declaration, initialized by *__begin. BlockScopeRAII InnerScope(Info); ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); if (ESR != ESR_Succeeded) return ESR; // Loop body. ESR = EvaluateLoopBody(Result, Info, FS->getBody()); if (ESR != ESR_Continue) return ESR; // Increment: ++__begin if (!EvaluateIgnoredValue(Info, FS->getInc())) return ESR_Failed; } return ESR_Succeeded; } case Stmt::SwitchStmtClass: return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); case Stmt::ContinueStmtClass: return ESR_Continue; case Stmt::BreakStmtClass: return ESR_Break; case Stmt::LabelStmtClass: return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); case Stmt::AttributedStmtClass: // As a general principle, C++11 attributes can be ignored without // any semantic impact. return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), Case); case Stmt::CaseStmtClass: case Stmt::DefaultStmtClass: return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); } } /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial /// default constructor. If so, we'll fold it whether or not it's marked as /// constexpr. If it is marked as constexpr, we will never implicitly define it, /// so we need special handling. static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, const CXXConstructorDecl *CD, bool IsValueInitialization) { if (!CD->isTrivial() || !CD->isDefaultConstructor()) return false; // Value-initialization does not call a trivial default constructor, so such a // call is a core constant expression whether or not the constructor is // constexpr. if (!CD->isConstexpr() && !IsValueInitialization) { if (Info.getLangOpts().CPlusPlus11) { // FIXME: If DiagDecl is an implicitly-declared special member function, // we should be much more explicit about why it's not constexpr. Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; Info.Note(CD->getLocation(), diag::note_declared_at); } else { Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); } } return true; } /// CheckConstexprFunction - Check that a function can be called in a constant /// expression. static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, const FunctionDecl *Declaration, const FunctionDecl *Definition, const Stmt *Body) { // Potential constant expressions can contain calls to declared, but not yet // defined, constexpr functions. if (Info.checkingPotentialConstantExpression() && !Definition && Declaration->isConstexpr()) return false; // Bail out with no diagnostic if the function declaration itself is invalid. // We will have produced a relevant diagnostic while parsing it. if (Declaration->isInvalidDecl()) return false; // Can we evaluate this function call? if (Definition && Definition->isConstexpr() && !Definition->isInvalidDecl() && Body) return true; if (Info.getLangOpts().CPlusPlus11) { const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; // If this function is not constexpr because it is an inherited // non-constexpr constructor, diagnose that directly. auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl); if (CD && CD->isInheritingConstructor()) { auto *Inherited = CD->getInheritedConstructor().getConstructor(); if (!Inherited->isConstexpr()) DiagDecl = CD = Inherited; } // FIXME: If DiagDecl is an implicitly-declared special member function // or an inheriting constructor, we should be much more explicit about why // it's not constexpr. if (CD && CD->isInheritingConstructor()) Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1) << CD->getInheritedConstructor().getConstructor()->getParent(); else Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1) << DiagDecl->isConstexpr() << (bool)CD << DiagDecl; Info.Note(DiagDecl->getLocation(), diag::note_declared_at); } else { Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); } return false; } /// Determine if a class has any fields that might need to be copied by a /// trivial copy or move operation. static bool hasFields(const CXXRecordDecl *RD) { if (!RD || RD->isEmpty()) return false; for (auto *FD : RD->fields()) { if (FD->isUnnamedBitfield()) continue; return true; } for (auto &Base : RD->bases()) if (hasFields(Base.getType()->getAsCXXRecordDecl())) return true; return false; } namespace { typedef SmallVector<APValue, 8> ArgVector; } /// EvaluateArgs - Evaluate the arguments to a function call. static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues, EvalInfo &Info) { bool Success = true; for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); I != E; ++I) { if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { // If we're checking for a potential constant expression, evaluate all // initializers even if some of them fail. if (!Info.noteFailure()) return false; Success = false; } } return Success; } /// Evaluate a function call. static bool HandleFunctionCall(SourceLocation CallLoc, const FunctionDecl *Callee, const LValue *This, ArrayRef<const Expr*> Args, const Stmt *Body, EvalInfo &Info, APValue &Result, const LValue *ResultSlot) { ArgVector ArgValues(Args.size()); if (!EvaluateArgs(Args, ArgValues, Info)) return false; if (!Info.CheckCallLimit(CallLoc)) return false; CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); // For a trivial copy or move assignment, perform an APValue copy. This is // essential for unions, where the operations performed by the assignment // operator cannot be represented as statements. // // Skip this for non-union classes with no fields; in that case, the defaulted // copy/move does not actually read the object. const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); if (MD && MD->isDefaulted() && (MD->getParent()->isUnion() || (MD->isTrivial() && hasFields(MD->getParent())))) { assert(This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); LValue RHS; RHS.setFrom(Info.Ctx, ArgValues[0]); APValue RHSValue; if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), RHS, RHSValue)) return false; if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx), RHSValue)) return false; This->moveInto(Result); return true; } StmtResult Ret = {Result, ResultSlot}; EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body); if (ESR == ESR_Succeeded) { if (Callee->getReturnType()->isVoidType()) return true; Info.FFDiag(Callee->getLocEnd(), diag::note_constexpr_no_return); } return ESR == ESR_Returned; } /// Evaluate a constructor call. static bool HandleConstructorCall(const Expr *E, const LValue &This, APValue *ArgValues, const CXXConstructorDecl *Definition, EvalInfo &Info, APValue &Result) { SourceLocation CallLoc = E->getExprLoc(); if (!Info.CheckCallLimit(CallLoc)) return false; const CXXRecordDecl *RD = Definition->getParent(); if (RD->getNumVBases()) { Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD; return false; } CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues); // FIXME: Creating an APValue just to hold a nonexistent return value is // wasteful. APValue RetVal; StmtResult Ret = {RetVal, nullptr}; // If it's a delegating constructor, delegate. if (Definition->isDelegatingConstructor()) { CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); { FullExpressionRAII InitScope(Info); if (!EvaluateInPlace(Result, Info, This, (*I)->getInit())) return false; } return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; } // For a trivial copy or move constructor, perform an APValue copy. This is // essential for unions (or classes with anonymous union members), where the // operations performed by the constructor cannot be represented by // ctor-initializers. // // Skip this for empty non-union classes; we should not perform an // lvalue-to-rvalue conversion on them because their copy constructor does not // actually read them. if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() && (Definition->getParent()->isUnion() || (Definition->isTrivial() && hasFields(Definition->getParent())))) { LValue RHS; RHS.setFrom(Info.Ctx, ArgValues[0]); return handleLValueToRValueConversion( Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(), RHS, Result); } // Reserve space for the struct members. if (!RD->isUnion() && Result.isUninit()) Result = APValue(APValue::UninitStruct(), RD->getNumBases(), std::distance(RD->field_begin(), RD->field_end())); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); // A scope for temporaries lifetime-extended by reference members. BlockScopeRAII LifetimeExtendedScope(Info); bool Success = true; unsigned BasesSeen = 0; #ifndef NDEBUG CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); #endif for (const auto *I : Definition->inits()) { LValue Subobject = This; APValue *Value = &Result; // Determine the subobject to initialize. FieldDecl *FD = nullptr; if (I->isBaseInitializer()) { QualType BaseType(I->getBaseClass(), 0); #ifndef NDEBUG // Non-virtual base classes are initialized in the order in the class // definition. We have already checked for virtual base classes. assert(!BaseIt->isVirtual() && "virtual base for literal type"); assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && "base class initializers not in expected order"); ++BaseIt; #endif if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD, BaseType->getAsCXXRecordDecl(), &Layout)) return false; Value = &Result.getStructBase(BasesSeen++); } else if ((FD = I->getMember())) { if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout)) return false; if (RD->isUnion()) { Result = APValue(FD); Value = &Result.getUnionValue(); } else { Value = &Result.getStructField(FD->getFieldIndex()); } } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) { // Walk the indirect field decl's chain to find the object to initialize, // and make sure we've initialized every step along it. for (auto *C : IFD->chain()) { FD = cast<FieldDecl>(C); CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); // Switch the union field if it differs. This happens if we had // preceding zero-initialization, and we're now initializing a union // subobject other than the first. // FIXME: In this case, the values of the other subobjects are // specified, since zero-initialization sets all padding bits to zero. if (Value->isUninit() || (Value->isUnion() && Value->getUnionField() != FD)) { if (CD->isUnion()) *Value = APValue(FD); else *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), std::distance(CD->field_begin(), CD->field_end())); } if (!HandleLValueMember(Info, I->getInit(), Subobject, FD)) return false; if (CD->isUnion()) Value = &Value->getUnionValue(); else Value = &Value->getStructField(FD->getFieldIndex()); } } else { llvm_unreachable("unknown base initializer kind"); } FullExpressionRAII InitScope(Info); if (!EvaluateInPlace(*Value, Info, Subobject, I->getInit()) || (FD && FD->isBitField() && !truncateBitfieldValue(Info, I->getInit(), *Value, FD))) { // If we're checking for a potential constant expression, evaluate all // initializers even if some of them fail. if (!Info.noteFailure()) return false; Success = false; } } return Success && EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; } static bool HandleConstructorCall(const Expr *E, const LValue &This, ArrayRef<const Expr*> Args, const CXXConstructorDecl *Definition, EvalInfo &Info, APValue &Result) { ArgVector ArgValues(Args.size()); if (!EvaluateArgs(Args, ArgValues, Info)) return false; return HandleConstructorCall(E, This, ArgValues.data(), Definition, Info, Result); } //===----------------------------------------------------------------------===// // Generic Evaluation //===----------------------------------------------------------------------===// namespace { template <class Derived> class ExprEvaluatorBase : public ConstStmtVisitor<Derived, bool> { private: Derived &getDerived() { return static_cast<Derived&>(*this); } bool DerivedSuccess(const APValue &V, const Expr *E) { return getDerived().Success(V, E); } bool DerivedZeroInitialization(const Expr *E) { return getDerived().ZeroInitialization(E); } // Check whether a conditional operator with a non-constant condition is a // potential constant expression. If neither arm is a potential constant // expression, then the conditional operator is not either. template<typename ConditionalOperator> void CheckPotentialConstantConditional(const ConditionalOperator *E) { assert(Info.checkingPotentialConstantExpression()); // Speculatively evaluate both arms. SmallVector<PartialDiagnosticAt, 8> Diag; { SpeculativeEvaluationRAII Speculate(Info, &Diag); StmtVisitorTy::Visit(E->getFalseExpr()); if (Diag.empty()) return; } { SpeculativeEvaluationRAII Speculate(Info, &Diag); Diag.clear(); StmtVisitorTy::Visit(E->getTrueExpr()); if (Diag.empty()) return; } Error(E, diag::note_constexpr_conditional_never_const); } template<typename ConditionalOperator> bool HandleConditionalOperator(const ConditionalOperator *E) { bool BoolResult; if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) CheckPotentialConstantConditional(E); return false; } Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); return StmtVisitorTy::Visit(EvalExpr); } protected: EvalInfo &Info; typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy; typedef ExprEvaluatorBase ExprEvaluatorBaseTy; OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { return Info.CCEDiag(E, D); } bool ZeroInitialization(const Expr *E) { return Error(E); } public: ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} EvalInfo &getEvalInfo() { return Info; } /// Report an evaluation error. This should only be called when an error is /// first discovered. When propagating an error, just return false. bool Error(const Expr *E, diag::kind D) { Info.FFDiag(E, D); return false; } bool Error(const Expr *E) { return Error(E, diag::note_invalid_subexpr_in_const_expr); } bool VisitStmt(const Stmt *) { llvm_unreachable("Expression evaluator should not be called on stmts"); } bool VisitExpr(const Expr *E) { return Error(E); } bool VisitParenExpr(const ParenExpr *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitUnaryExtension(const UnaryOperator *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitUnaryPlus(const UnaryOperator *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitChooseExpr(const ChooseExpr *E) { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) { return StmtVisitorTy::Visit(E->getResultExpr()); } bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) { return StmtVisitorTy::Visit(E->getReplacement()); } bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) { return StmtVisitorTy::Visit(E->getExpr()); } bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { // The initializer may not have been parsed yet, or might be erroneous. if (!E->getExpr()) return Error(E); return StmtVisitorTy::Visit(E->getExpr()); } // We cannot create any objects for which cleanups are required, so there is // nothing to do here; all cleanups must come from unevaluated subexpressions. bool VisitExprWithCleanups(const ExprWithCleanups *E) { return StmtVisitorTy::Visit(E->getSubExpr()); } bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; return static_cast<Derived*>(this)->VisitCastExpr(E); } bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; return static_cast<Derived*>(this)->VisitCastExpr(E); } bool VisitBinaryOperator(const BinaryOperator *E) { switch (E->getOpcode()) { default: return Error(E); case BO_Comma: VisitIgnoredValue(E->getLHS()); return StmtVisitorTy::Visit(E->getRHS()); case BO_PtrMemD: case BO_PtrMemI: { LValue Obj; if (!HandleMemberPointerAccess(Info, E, Obj)) return false; APValue Result; if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) return false; return DerivedSuccess(Result, E); } } } bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { // Evaluate and cache the common expression. We treat it as a temporary, // even though it's not quite the same thing. if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false), Info, E->getCommon())) return false; return HandleConditionalOperator(E); } bool VisitConditionalOperator(const ConditionalOperator *E) { bool IsBcpCall = false; // If the condition (ignoring parens) is a __builtin_constant_p call, // the result is a constant expression if it can be folded without // side-effects. This is an important GNU extension. See GCC PR38377 // for discussion. if (const CallExpr *CallCE = dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) IsBcpCall = true; // Always assume __builtin_constant_p(...) ? ... : ... is a potential // constant expression; we can't check whether it's potentially foldable. if (Info.checkingPotentialConstantExpression() && IsBcpCall) return false; FoldConstant Fold(Info, IsBcpCall); if (!HandleConditionalOperator(E)) { Fold.keepDiagnostics(); return false; } return true; } bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) { if (APValue *Value = Info.CurrentCall->getTemporary(E)) return DerivedSuccess(*Value, E); const Expr *Source = E->getSourceExpr(); if (!Source) return Error(E); if (Source == E) { // sanity checking. assert(0 && "OpaqueValueExpr recursively refers to itself"); return Error(E); } return StmtVisitorTy::Visit(Source); } bool VisitCallExpr(const CallExpr *E) { APValue Result; if (!handleCallExpr(E, Result, nullptr)) return false; return DerivedSuccess(Result, E); } bool handleCallExpr(const CallExpr *E, APValue &Result, const LValue *ResultSlot) { const Expr *Callee = E->getCallee()->IgnoreParens(); QualType CalleeType = Callee->getType(); const FunctionDecl *FD = nullptr; LValue *This = nullptr, ThisVal; auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); bool HasQualifier = false; // Extract function decl and 'this' pointer from the callee. if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { const ValueDecl *Member = nullptr; if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { // Explicit bound member calls, such as x.f() or p->g(); if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) return false; Member = ME->getMemberDecl(); This = &ThisVal; HasQualifier = ME->hasQualifier(); } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { // Indirect bound member calls ('.*' or '->*'). Member = HandleMemberPointerAccess(Info, BE, ThisVal, false); if (!Member) return false; This = &ThisVal; } else return Error(Callee); FD = dyn_cast<FunctionDecl>(Member); if (!FD) return Error(Callee); } else if (CalleeType->isFunctionPointerType()) { LValue Call; if (!EvaluatePointer(Callee, Call, Info)) return false; if (!Call.getLValueOffset().isZero()) return Error(Callee); FD = dyn_cast_or_null<FunctionDecl>( Call.getLValueBase().dyn_cast<const ValueDecl*>()); if (!FD) return Error(Callee); // Overloaded operator calls to member functions are represented as normal // calls with '*this' as the first argument. const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); if (MD && !MD->isStatic()) { // FIXME: When selecting an implicit conversion for an overloaded // operator delete, we sometimes try to evaluate calls to conversion // operators without a 'this' parameter! if (Args.empty()) return Error(E); if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) return false; This = &ThisVal; Args = Args.slice(1); } // Don't call function pointers which have been cast to some other type. if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType())) return Error(E); } else return Error(E); if (This && !This->checkSubobject(Info, E, CSK_This)) return false; // DR1358 allows virtual constexpr functions in some cases. Don't allow // calls to such functions in constant expressions. if (This && !HasQualifier && isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual()) return Error(E, diag::note_constexpr_virtual_call); const FunctionDecl *Definition = nullptr; Stmt *Body = FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) || !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info, Result, ResultSlot)) return false; return true; } bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { return StmtVisitorTy::Visit(E->getInitializer()); } bool VisitInitListExpr(const InitListExpr *E) { if (E->getNumInits() == 0) return DerivedZeroInitialization(E); if (E->getNumInits() == 1) return StmtVisitorTy::Visit(E->getInit(0)); return Error(E); } bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { return DerivedZeroInitialization(E); } bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { return DerivedZeroInitialization(E); } bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { return DerivedZeroInitialization(E); } /// A member expression where the object is a prvalue is itself a prvalue. bool VisitMemberExpr(const MemberExpr *E) { assert(!E->isArrow() && "missing call to bound member function?"); APValue Val; if (!Evaluate(Val, Info, E->getBase())) return false; QualType BaseTy = E->getBase()->getType(); const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); if (!FD) return Error(E); assert(!FD->getType()->isReferenceType() && "prvalue reference?"); assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"); CompleteObject Obj(&Val, BaseTy); SubobjectDesignator Designator(BaseTy); Designator.addDeclUnchecked(FD); APValue Result; return extractSubobject(Info, E, Obj, Designator, Result) && DerivedSuccess(Result, E); } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: break; case CK_AtomicToNonAtomic: { APValue AtomicVal; if (!EvaluateAtomic(E->getSubExpr(), AtomicVal, Info)) return false; return DerivedSuccess(AtomicVal, E); } case CK_NoOp: case CK_UserDefinedConversion: return StmtVisitorTy::Visit(E->getSubExpr()); case CK_LValueToRValue: { LValue LVal; if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) return false; APValue RVal; // Note, we use the subexpression's type in order to retain cv-qualifiers. if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), LVal, RVal)) return false; return DerivedSuccess(RVal, E); } } return Error(E); } bool VisitUnaryPostInc(const UnaryOperator *UO) { return VisitUnaryPostIncDec(UO); } bool VisitUnaryPostDec(const UnaryOperator *UO) { return VisitUnaryPostIncDec(UO); } bool VisitUnaryPostIncDec(const UnaryOperator *UO) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(UO); LValue LVal; if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) return false; APValue RVal; if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), UO->isIncrementOp(), &RVal)) return false; return DerivedSuccess(RVal, UO); } bool VisitStmtExpr(const StmtExpr *E) { // We will have checked the full-expressions inside the statement expression // when they were completed, and don't need to check them again now. if (Info.checkingForOverflow()) return Error(E); BlockScopeRAII Scope(Info); const CompoundStmt *CS = E->getSubStmt(); if (CS->body_empty()) return true; for (CompoundStmt::const_body_iterator BI = CS->body_begin(), BE = CS->body_end(); /**/; ++BI) { if (BI + 1 == BE) { const Expr *FinalExpr = dyn_cast<Expr>(*BI); if (!FinalExpr) { Info.FFDiag((*BI)->getLocStart(), diag::note_constexpr_stmt_expr_unsupported); return false; } return this->Visit(FinalExpr); } APValue ReturnValue; StmtResult Result = { ReturnValue, nullptr }; EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI); if (ESR != ESR_Succeeded) { // FIXME: If the statement-expression terminated due to 'return', // 'break', or 'continue', it would be nice to propagate that to // the outer statement evaluation rather than bailing out. if (ESR != ESR_Failed) Info.FFDiag((*BI)->getLocStart(), diag::note_constexpr_stmt_expr_unsupported); return false; } } llvm_unreachable("Return from function from the loop above."); } /// Visit a value which is evaluated, but whose value is ignored. void VisitIgnoredValue(const Expr *E) { EvaluateIgnoredValue(Info, E); } /// Potentially visit a MemberExpr's base expression. void VisitIgnoredBaseExpression(const Expr *E) { // While MSVC doesn't evaluate the base expression, it does diagnose the // presence of side-effecting behavior. if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx)) return; VisitIgnoredValue(E); } }; } //===----------------------------------------------------------------------===// // Common base class for lvalue and temporary evaluation. //===----------------------------------------------------------------------===// namespace { template<class Derived> class LValueExprEvaluatorBase : public ExprEvaluatorBase<Derived> { protected: LValue &Result; typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy; bool Success(APValue::LValueBase B) { Result.set(B); return true; } public: LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result) : ExprEvaluatorBaseTy(Info), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(this->Info.Ctx, V); return true; } bool VisitMemberExpr(const MemberExpr *E) { // Handle non-static data members. QualType BaseTy; bool EvalOK; if (E->isArrow()) { EvalOK = EvaluatePointer(E->getBase(), Result, this->Info); BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); } else if (E->getBase()->isRValue()) { assert(E->getBase()->getType()->isRecordType()); EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info); BaseTy = E->getBase()->getType(); } else { EvalOK = this->Visit(E->getBase()); BaseTy = E->getBase()->getType(); } if (!EvalOK) { if (!this->Info.allowInvalidBaseExpr()) return false; Result.setInvalid(E); return true; } const ValueDecl *MD = E->getMemberDecl(); if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"); (void)BaseTy; if (!HandleLValueMember(this->Info, E, Result, FD)) return false; } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) return false; } else return this->Error(E); if (MD->getType()->isReferenceType()) { APValue RefValue; if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, RefValue)) return false; return Success(RefValue, E); } return true; } bool VisitBinaryOperator(const BinaryOperator *E) { switch (E->getOpcode()) { default: return ExprEvaluatorBaseTy::VisitBinaryOperator(E); case BO_PtrMemD: case BO_PtrMemI: return HandleMemberPointerAccess(this->Info, E, Result); } } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_DerivedToBase: case CK_UncheckedDerivedToBase: if (!this->Visit(E->getSubExpr())) return false; // Now figure out the necessary offset to add to the base LV to get from // the derived class to the base class. return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), Result); } } }; } //===----------------------------------------------------------------------===// // LValue Evaluation // // This is used for evaluating lvalues (in C and C++), xvalues (in C++11), // function designators (in C), decl references to void objects (in C), and // temporaries (if building with -Wno-address-of-temporary). // // LValue evaluation produces values comprising a base expression of one of the // following types: // - Declarations // * VarDecl // * FunctionDecl // - Literals // * CompoundLiteralExpr in C // * StringLiteral // * CXXTypeidExpr // * PredefinedExpr // * ObjCStringLiteralExpr // * ObjCEncodeExpr // * AddrLabelExpr // * BlockExpr // * CallExpr for a MakeStringConstant builtin // - Locals and temporaries // * MaterializeTemporaryExpr // * Any Expr, with a CallIndex indicating the function in which the temporary // was evaluated, for cases where the MaterializeTemporaryExpr is missing // from the AST (FIXME). // * A MaterializeTemporaryExpr that has static storage duration, with no // CallIndex, for a lifetime-extended temporary. // plus an offset in bytes. //===----------------------------------------------------------------------===// namespace { class LValueExprEvaluator : public LValueExprEvaluatorBase<LValueExprEvaluator> { public: LValueExprEvaluator(EvalInfo &Info, LValue &Result) : LValueExprEvaluatorBaseTy(Info, Result) {} bool VisitVarDecl(const Expr *E, const VarDecl *VD); bool VisitUnaryPreIncDec(const UnaryOperator *UO); bool VisitDeclRefExpr(const DeclRefExpr *E); bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); bool VisitMemberExpr(const MemberExpr *E); bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); bool VisitUnaryDeref(const UnaryOperator *E); bool VisitUnaryReal(const UnaryOperator *E); bool VisitUnaryImag(const UnaryOperator *E); bool VisitUnaryPreInc(const UnaryOperator *UO) { return VisitUnaryPreIncDec(UO); } bool VisitUnaryPreDec(const UnaryOperator *UO) { return VisitUnaryPreIncDec(UO); } bool VisitBinAssign(const BinaryOperator *BO); bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return LValueExprEvaluatorBaseTy::VisitCastExpr(E); case CK_LValueBitCast: this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; if (!Visit(E->getSubExpr())) return false; Result.Designator.setInvalid(); return true; case CK_BaseToDerived: if (!Visit(E->getSubExpr())) return false; return HandleBaseToDerivedCast(Info, E, Result); } } }; } // end anonymous namespace /// Evaluate an expression as an lvalue. This can be legitimately called on /// expressions which are not glvalues, in three cases: /// * function designators in C, and /// * "extern void" objects /// * @selector() expressions in Objective-C static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info) { assert(E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)); return LValueExprEvaluator(Info, Result).Visit(E); } bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) return Success(FD); if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) return VisitVarDecl(E, VD); return Error(E); } bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { CallStackFrame *Frame = nullptr; if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) Frame = Info.CurrentCall; if (!VD->getType()->isReferenceType()) { if (Frame) { Result.set(VD, Frame->Index); return true; } return Success(VD); } APValue *V; if (!evaluateVarDeclInit(Info, E, VD, Frame, V)) return false; if (V->isUninit()) { if (!Info.checkingPotentialConstantExpression()) Info.FFDiag(E, diag::note_constexpr_use_uninit_reference); return false; } return Success(*V, E); } bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( const MaterializeTemporaryExpr *E) { // Walk through the expression to find the materialized temporary itself. SmallVector<const Expr *, 2> CommaLHSs; SmallVector<SubobjectAdjustment, 2> Adjustments; const Expr *Inner = E->GetTemporaryExpr()-> skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); // If we passed any comma operators, evaluate their LHSs. for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) return false; // A materialized temporary with static storage duration can appear within the // result of a constant expression evaluation, so we need to preserve its // value for use outside this evaluation. APValue *Value; if (E->getStorageDuration() == SD_Static) { Value = Info.Ctx.getMaterializedTemporaryValue(E, true); *Value = APValue(); Result.set(E); } else { Value = &Info.CurrentCall-> createTemporary(E, E->getStorageDuration() == SD_Automatic); Result.set(E, Info.CurrentCall->Index); } QualType Type = Inner->getType(); // Materialize the temporary itself. if (!EvaluateInPlace(*Value, Info, Result, Inner) || (E->getStorageDuration() == SD_Static && !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) { *Value = APValue(); return false; } // Adjust our lvalue to refer to the desired subobject. for (unsigned I = Adjustments.size(); I != 0; /**/) { --I; switch (Adjustments[I].Kind) { case SubobjectAdjustment::DerivedToBaseAdjustment: if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, Type, Result)) return false; Type = Adjustments[I].DerivedToBase.BasePath->getType(); break; case SubobjectAdjustment::FieldAdjustment: if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) return false; Type = Adjustments[I].Field->getType(); break; case SubobjectAdjustment::MemberPointerAdjustment: if (!HandleMemberPointerAccess(this->Info, Type, Result, Adjustments[I].Ptr.RHS)) return false; Type = Adjustments[I].Ptr.MPT->getPointeeType(); break; } } return true; } bool LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); // Defer visiting the literal until the lvalue-to-rvalue conversion. We can // only see this when folding in C, so there's no standard to follow here. return Success(E); } bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { if (!E->isPotentiallyEvaluated()) return Success(E); Info.FFDiag(E, diag::note_constexpr_typeid_polymorphic) << E->getExprOperand()->getType() << E->getExprOperand()->getSourceRange(); return false; } bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { return Success(E); } bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { // Handle static data members. if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { VisitIgnoredBaseExpression(E->getBase()); return VisitVarDecl(E, VD); } // Handle static member functions. if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { if (MD->isStatic()) { VisitIgnoredBaseExpression(E->getBase()); return Success(MD); } } // Handle non-static data members. return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); } bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { // FIXME: Deal with vectors as array subscript bases. if (E->getBase()->getType()->isVectorType()) return Error(E); if (!EvaluatePointer(E->getBase(), Result, Info)) return false; APSInt Index; if (!EvaluateInteger(E->getIdx(), Index, Info)) return false; return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), getExtValue(Index)); } bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { return EvaluatePointer(E->getSubExpr(), Result, Info); } bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { if (!Visit(E->getSubExpr())) return false; // __real is a no-op on scalar lvalues. if (E->getSubExpr()->getType()->isAnyComplexType()) HandleLValueComplexElement(Info, E, Result, E->getType(), false); return true; } bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { assert(E->getSubExpr()->getType()->isAnyComplexType() && "lvalue __imag__ on scalar?"); if (!Visit(E->getSubExpr())) return false; HandleLValueComplexElement(Info, E, Result, E->getType(), true); return true; } bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(UO); if (!this->Visit(UO->getSubExpr())) return false; return handleIncDec( this->Info, UO, Result, UO->getSubExpr()->getType(), UO->isIncrementOp(), nullptr); } bool LValueExprEvaluator::VisitCompoundAssignOperator( const CompoundAssignOperator *CAO) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(CAO); APValue RHS; // The overall lvalue result is the result of evaluating the LHS. if (!this->Visit(CAO->getLHS())) { if (Info.noteFailure()) Evaluate(RHS, this->Info, CAO->getRHS()); return false; } if (!Evaluate(RHS, this->Info, CAO->getRHS())) return false; return handleCompoundAssignment( this->Info, CAO, Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); } bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) return Error(E); APValue NewVal; if (!this->Visit(E->getLHS())) { if (Info.noteFailure()) Evaluate(NewVal, this->Info, E->getRHS()); return false; } if (!Evaluate(NewVal, this->Info, E->getRHS())) return false; return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), NewVal); } //===----------------------------------------------------------------------===// // Pointer Evaluation //===----------------------------------------------------------------------===// namespace { class PointerExprEvaluator : public ExprEvaluatorBase<PointerExprEvaluator> { LValue &Result; bool Success(const Expr *E) { Result.set(E); return true; } public: PointerExprEvaluator(EvalInfo &info, LValue &Result) : ExprEvaluatorBaseTy(info), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(Info.Ctx, V); return true; } bool ZeroInitialization(const Expr *E) { return Success((Expr*)nullptr); } bool VisitBinaryOperator(const BinaryOperator *E); bool VisitCastExpr(const CastExpr* E); bool VisitUnaryAddrOf(const UnaryOperator *E); bool VisitObjCStringLiteral(const ObjCStringLiteral *E) { return Success(E); } bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) { return Success(E); } bool VisitAddrLabelExpr(const AddrLabelExpr *E) { return Success(E); } bool VisitCallExpr(const CallExpr *E); bool VisitBlockExpr(const BlockExpr *E) { if (!E->getBlockDecl()->hasCaptures()) return Success(E); return Error(E); } bool VisitCXXThisExpr(const CXXThisExpr *E) { // Can't look at 'this' when checking a potential constant expression. if (Info.checkingPotentialConstantExpression()) return false; if (!Info.CurrentCall->This) { if (Info.getLangOpts().CPlusPlus11) Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit(); else Info.FFDiag(E); return false; } Result = *Info.CurrentCall->This; return true; } // FIXME: Missing: @protocol, @selector }; } // end anonymous namespace static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->hasPointerRepresentation()); return PointerExprEvaluator(Info, Result).Visit(E); } bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->getOpcode() != BO_Add && E->getOpcode() != BO_Sub) return ExprEvaluatorBaseTy::VisitBinaryOperator(E); const Expr *PExp = E->getLHS(); const Expr *IExp = E->getRHS(); if (IExp->getType()->isPointerType()) std::swap(PExp, IExp); bool EvalPtrOK = EvaluatePointer(PExp, Result, Info); if (!EvalPtrOK && !Info.noteFailure()) return false; llvm::APSInt Offset; if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) return false; int64_t AdditionalOffset = getExtValue(Offset); if (E->getOpcode() == BO_Sub) AdditionalOffset = -AdditionalOffset; QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); return HandleLValueArrayAdjustment(Info, E, Result, Pointee, AdditionalOffset); } bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { return EvaluateLValue(E->getSubExpr(), Result, Info); } bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) { const Expr* SubExpr = E->getSubExpr(); switch (E->getCastKind()) { default: break; case CK_BitCast: case CK_CPointerToObjCPointerCast: case CK_BlockPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_AddressSpaceConversion: if (!Visit(SubExpr)) return false; // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are // permitted in constant expressions in C++11. Bitcasts from cv void* are // also static_casts, but we disallow them as a resolution to DR1312. if (!E->getType()->isVoidPointerType()) { Result.Designator.setInvalid(); if (SubExpr->getType()->isVoidPointerType()) CCEDiag(E, diag::note_constexpr_invalid_cast) << 3 << SubExpr->getType(); else CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; } return true; case CK_DerivedToBase: case CK_UncheckedDerivedToBase: if (!EvaluatePointer(E->getSubExpr(), Result, Info)) return false; if (!Result.Base && Result.Offset.isZero()) return true; // Now figure out the necessary offset to add to the base LV to get from // the derived class to the base class. return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> castAs<PointerType>()->getPointeeType(), Result); case CK_BaseToDerived: if (!Visit(E->getSubExpr())) return false; if (!Result.Base && Result.Offset.isZero()) return true; return HandleBaseToDerivedCast(Info, E, Result); case CK_NullToPointer: VisitIgnoredValue(E->getSubExpr()); return ZeroInitialization(E); case CK_IntegralToPointer: { CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; APValue Value; if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) break; if (Value.isInt()) { unsigned Size = Info.Ctx.getTypeSize(E->getType()); uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); Result.Base = (Expr*)nullptr; Result.InvalidBase = false; Result.Offset = CharUnits::fromQuantity(N); Result.CallIndex = 0; Result.Designator.setInvalid(); return true; } else { // Cast is of an lvalue, no need to change value. Result.setFrom(Info.Ctx, Value); return true; } } case CK_ArrayToPointerDecay: if (SubExpr->isGLValue()) { if (!EvaluateLValue(SubExpr, Result, Info)) return false; } else { Result.set(SubExpr, Info.CurrentCall->Index); if (!EvaluateInPlace(Info.CurrentCall->createTemporary(SubExpr, false), Info, Result, SubExpr)) return false; } // The result is a pointer to the first element of the array. if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(SubExpr->getType())) Result.addArray(Info, E, CAT); else Result.Designator.setInvalid(); return true; case CK_FunctionToPointerDecay: return EvaluateLValue(SubExpr, Result, Info); } return ExprEvaluatorBaseTy::VisitCastExpr(E); } static CharUnits GetAlignOfType(EvalInfo &Info, QualType T) { // C++ [expr.alignof]p3: // When alignof is applied to a reference type, the result is the // alignment of the referenced type. if (const ReferenceType *Ref = T->getAs<ReferenceType>()) T = Ref->getPointeeType(); // __alignof is defined to return the preferred alignment. return Info.Ctx.toCharUnitsFromBits( Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); } static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E) { E = E->IgnoreParens(); // The kinds of expressions that we have special-case logic here for // should be kept up to date with the special checks for those // expressions in Sema. // alignof decl is always accepted, even if it doesn't make sense: we default // to 1 in those cases. if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) return Info.Ctx.getDeclAlign(DRE->getDecl(), /*RefAsPointee*/true); if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) return Info.Ctx.getDeclAlign(ME->getMemberDecl(), /*RefAsPointee*/true); return GetAlignOfType(Info, E->getType()); } bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { if (IsStringLiteralCall(E)) return Success(E); switch (E->getBuiltinCallee()) { case Builtin::BI__builtin_addressof: return EvaluateLValue(E->getArg(0), Result, Info); case Builtin::BI__builtin_assume_aligned: { // We need to be very careful here because: if the pointer does not have the // asserted alignment, then the behavior is undefined, and undefined // behavior is non-constant. if (!EvaluatePointer(E->getArg(0), Result, Info)) return false; LValue OffsetResult(Result); APSInt Alignment; if (!EvaluateInteger(E->getArg(1), Alignment, Info)) return false; CharUnits Align = CharUnits::fromQuantity(getExtValue(Alignment)); if (E->getNumArgs() > 2) { APSInt Offset; if (!EvaluateInteger(E->getArg(2), Offset, Info)) return false; int64_t AdditionalOffset = -getExtValue(Offset); OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset); } // If there is a base object, then it must have the correct alignment. if (OffsetResult.Base) { CharUnits BaseAlignment; if (const ValueDecl *VD = OffsetResult.Base.dyn_cast<const ValueDecl*>()) { BaseAlignment = Info.Ctx.getDeclAlign(VD); } else { BaseAlignment = GetAlignOfExpr(Info, OffsetResult.Base.get<const Expr*>()); } if (BaseAlignment < Align) { Result.Designator.setInvalid(); // FIXME: Quantities here cast to integers because the plural modifier // does not work on APSInts yet. CCEDiag(E->getArg(0), diag::note_constexpr_baa_insufficient_alignment) << 0 << (int) BaseAlignment.getQuantity() << (unsigned) getExtValue(Alignment); return false; } } // The offset must also have the correct alignment. if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) { Result.Designator.setInvalid(); APSInt Offset(64, false); Offset = OffsetResult.Offset.getQuantity(); if (OffsetResult.Base) CCEDiag(E->getArg(0), diag::note_constexpr_baa_insufficient_alignment) << 1 << (int) getExtValue(Offset) << (unsigned) getExtValue(Alignment); else CCEDiag(E->getArg(0), diag::note_constexpr_baa_value_insufficient_alignment) << Offset << (unsigned) getExtValue(Alignment); return false; } return true; } default: return ExprEvaluatorBaseTy::VisitCallExpr(E); } } //===----------------------------------------------------------------------===// // Member Pointer Evaluation //===----------------------------------------------------------------------===// namespace { class MemberPointerExprEvaluator : public ExprEvaluatorBase<MemberPointerExprEvaluator> { MemberPtr &Result; bool Success(const ValueDecl *D) { Result = MemberPtr(D); return true; } public: MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) : ExprEvaluatorBaseTy(Info), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result.setFrom(V); return true; } bool ZeroInitialization(const Expr *E) { return Success((const ValueDecl*)nullptr); } bool VisitCastExpr(const CastExpr *E); bool VisitUnaryAddrOf(const UnaryOperator *E); }; } // end anonymous namespace static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isMemberPointerType()); return MemberPointerExprEvaluator(Info, Result).Visit(E); } bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_NullToMemberPointer: VisitIgnoredValue(E->getSubExpr()); return ZeroInitialization(E); case CK_BaseToDerivedMemberPointer: { if (!Visit(E->getSubExpr())) return false; if (E->path_empty()) return true; // Base-to-derived member pointer casts store the path in derived-to-base // order, so iterate backwards. The CXXBaseSpecifier also provides us with // the wrong end of the derived->base arc, so stagger the path by one class. typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); PathI != PathE; ++PathI) { assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); if (!Result.castToDerived(Derived)) return Error(E); } const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) return Error(E); return true; } case CK_DerivedToBaseMemberPointer: if (!Visit(E->getSubExpr())) return false; for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); if (!Result.castToBase(Base)) return Error(E); } return true; } } bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { // C++11 [expr.unary.op]p3 has very strict rules on how the address of a // member can be formed. return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); } //===----------------------------------------------------------------------===// // Record Evaluation //===----------------------------------------------------------------------===// namespace { class RecordExprEvaluator : public ExprEvaluatorBase<RecordExprEvaluator> { const LValue &This; APValue &Result; public: RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result = V; return true; } bool ZeroInitialization(const Expr *E) { return ZeroInitialization(E, E->getType()); } bool ZeroInitialization(const Expr *E, QualType T); bool VisitCallExpr(const CallExpr *E) { return handleCallExpr(E, Result, &This); } bool VisitCastExpr(const CastExpr *E); bool VisitInitListExpr(const InitListExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E) { return VisitCXXConstructExpr(E, E->getType()); } bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T); bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); }; } /// Perform zero-initialization on an object of non-union class type. /// C++11 [dcl.init]p5: /// To zero-initialize an object or reference of type T means: /// [...] /// -- if T is a (possibly cv-qualified) non-union class type, /// each non-static data member and each base-class subobject is /// zero-initialized static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, const RecordDecl *RD, const LValue &This, APValue &Result) { assert(!RD->isUnion() && "Expected non-union class type"); const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, std::distance(RD->field_begin(), RD->field_end())); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); if (CD) { unsigned Index = 0; for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), End = CD->bases_end(); I != End; ++I, ++Index) { const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); LValue Subobject = This; if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) return false; if (!HandleClassZeroInitialization(Info, E, Base, Subobject, Result.getStructBase(Index))) return false; } } for (const auto *I : RD->fields()) { // -- if T is a reference type, no initialization is performed. if (I->getType()->isReferenceType()) continue; LValue Subobject = This; if (!HandleLValueMember(Info, E, Subobject, I, &Layout)) return false; ImplicitValueInitExpr VIE(I->getType()); if (!EvaluateInPlace( Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) return false; } return true; } bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) { const RecordDecl *RD = T->castAs<RecordType>()->getDecl(); if (RD->isInvalidDecl()) return false; if (RD->isUnion()) { // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the // object's first non-static named data member is zero-initialized RecordDecl::field_iterator I = RD->field_begin(); if (I == RD->field_end()) { Result = APValue((const FieldDecl*)nullptr); return true; } LValue Subobject = This; if (!HandleLValueMember(Info, E, Subobject, *I)) return false; Result = APValue(*I); ImplicitValueInitExpr VIE(I->getType()); return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); } if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD; return false; } return HandleClassZeroInitialization(Info, E, RD, This, Result); } bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ConstructorConversion: return Visit(E->getSubExpr()); case CK_DerivedToBase: case CK_UncheckedDerivedToBase: { APValue DerivedObject; if (!Evaluate(DerivedObject, Info, E->getSubExpr())) return false; if (!DerivedObject.isStruct()) return Error(E->getSubExpr()); // Derived-to-base rvalue conversion: just slice off the derived part. APValue *Value = &DerivedObject; const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); for (CastExpr::path_const_iterator PathI = E->path_begin(), PathE = E->path_end(); PathI != PathE; ++PathI) { assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); Value = &Value->getStructBase(getBaseIndex(RD, Base)); RD = Base; } Result = *Value; return true; } } } bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); if (RD->isUnion()) { const FieldDecl *Field = E->getInitializedFieldInUnion(); Result = APValue(Field); if (!Field) return true; // If the initializer list for a union does not contain any elements, the // first element of the union is value-initialized. // FIXME: The element should be initialized from an initializer list. // Is this difference ever observable for initializer lists which // we don't build? ImplicitValueInitExpr VIE(Field->getType()); const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; LValue Subobject = This; if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) return false; // Temporarily override This, in case there's a CXXDefaultInitExpr in here. ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, isa<CXXDefaultInitExpr>(InitExpr)); return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); } auto *CXXRD = dyn_cast<CXXRecordDecl>(RD); if (Result.isUninit()) Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0, std::distance(RD->field_begin(), RD->field_end())); unsigned ElementNo = 0; bool Success = true; // Initialize base classes. if (CXXRD) { for (const auto &Base : CXXRD->bases()) { assert(ElementNo < E->getNumInits() && "missing init for base class"); const Expr *Init = E->getInit(ElementNo); LValue Subobject = This; if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base)) return false; APValue &FieldVal = Result.getStructBase(ElementNo); if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) { if (!Info.noteFailure()) return false; Success = false; } ++ElementNo; } } // Initialize members. for (const auto *Field : RD->fields()) { // Anonymous bit-fields are not considered members of the class for // purposes of aggregate initialization. if (Field->isUnnamedBitfield()) continue; LValue Subobject = This; bool HaveInit = ElementNo < E->getNumInits(); // FIXME: Diagnostics here should point to the end of the initializer // list, not the start. if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, Subobject, Field, &Layout)) return false; // Perform an implicit value-initialization for members beyond the end of // the initializer list. ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; // Temporarily override This, in case there's a CXXDefaultInitExpr in here. ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, isa<CXXDefaultInitExpr>(Init)); APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || (Field->isBitField() && !truncateBitfieldValue(Info, Init, FieldVal, Field))) { if (!Info.noteFailure()) return false; Success = false; } } return Success; } bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T) { // Note that E's type is not necessarily the type of our class here; we might // be initializing an array element instead. const CXXConstructorDecl *FD = E->getConstructor(); if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; bool ZeroInit = E->requiresZeroInitialization(); if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { // If we've already performed zero-initialization, we're already done. if (!Result.isUninit()) return true; // We can get here in two different ways: // 1) We're performing value-initialization, and should zero-initialize // the object, or // 2) We're performing default-initialization of an object with a trivial // constexpr default constructor, in which case we should start the // lifetimes of all the base subobjects (there can be no data member // subobjects in this case) per [basic.life]p1. // Either way, ZeroInitialization is appropriate. return ZeroInitialization(E, T); } const FunctionDecl *Definition = nullptr; auto Body = FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) return false; // Avoid materializing a temporary for an elidable copy/move constructor. if (E->isElidable() && !ZeroInit) if (const MaterializeTemporaryExpr *ME = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0))) return Visit(ME->GetTemporaryExpr()); if (ZeroInit && !ZeroInitialization(E, T)) return false; auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); return HandleConstructorCall(E, This, Args, cast<CXXConstructorDecl>(Definition), Info, Result); } bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr( const CXXInheritedCtorInitExpr *E) { if (!Info.CurrentCall) { assert(Info.checkingPotentialConstantExpression()); return false; } const CXXConstructorDecl *FD = E->getConstructor(); if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; const FunctionDecl *Definition = nullptr; auto Body = FD->getBody(Definition); if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) return false; return HandleConstructorCall(E, This, Info.CurrentCall->Arguments, cast<CXXConstructorDecl>(Definition), Info, Result); } bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( const CXXStdInitializerListExpr *E) { const ConstantArrayType *ArrayType = Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); LValue Array; if (!EvaluateLValue(E->getSubExpr(), Array, Info)) return false; // Get a pointer to the first element of the array. Array.addArray(Info, E, ArrayType); // FIXME: Perform the checks on the field types in SemaInit. RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); RecordDecl::field_iterator Field = Record->field_begin(); if (Field == Record->field_end()) return Error(E); // Start pointer. if (!Field->getType()->isPointerType() || !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), ArrayType->getElementType())) return Error(E); // FIXME: What if the initializer_list type has base classes, etc? Result = APValue(APValue::UninitStruct(), 0, 2); Array.moveInto(Result.getStructField(0)); if (++Field == Record->field_end()) return Error(E); if (Field->getType()->isPointerType() && Info.Ctx.hasSameType(Field->getType()->getPointeeType(), ArrayType->getElementType())) { // End pointer. if (!HandleLValueArrayAdjustment(Info, E, Array, ArrayType->getElementType(), ArrayType->getSize().getZExtValue())) return false; Array.moveInto(Result.getStructField(1)); } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) // Length. Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); else return Error(E); if (++Field != Record->field_end()) return Error(E); return true; } static bool EvaluateRecord(const Expr *E, const LValue &This, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isRecordType() && "can't evaluate expression as a record rvalue"); return RecordExprEvaluator(Info, This, Result).Visit(E); } //===----------------------------------------------------------------------===// // Temporary Evaluation // // Temporaries are represented in the AST as rvalues, but generally behave like // lvalues. The full-object of which the temporary is a subobject is implicitly // materialized so that a reference can bind to it. //===----------------------------------------------------------------------===// namespace { class TemporaryExprEvaluator : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { public: TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : LValueExprEvaluatorBaseTy(Info, Result) {} /// Visit an expression which constructs the value of this temporary. bool VisitConstructExpr(const Expr *E) { Result.set(E, Info.CurrentCall->Index); return EvaluateInPlace(Info.CurrentCall->createTemporary(E, false), Info, Result, E); } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return LValueExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ConstructorConversion: return VisitConstructExpr(E->getSubExpr()); } } bool VisitInitListExpr(const InitListExpr *E) { return VisitConstructExpr(E); } bool VisitCXXConstructExpr(const CXXConstructExpr *E) { return VisitConstructExpr(E); } bool VisitCallExpr(const CallExpr *E) { return VisitConstructExpr(E); } bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) { return VisitConstructExpr(E); } }; } // end anonymous namespace /// Evaluate an expression of record type as a temporary. static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isRecordType()); return TemporaryExprEvaluator(Info, Result).Visit(E); } //===----------------------------------------------------------------------===// // Vector Evaluation //===----------------------------------------------------------------------===// namespace { class VectorExprEvaluator : public ExprEvaluatorBase<VectorExprEvaluator> { APValue &Result; public: VectorExprEvaluator(EvalInfo &info, APValue &Result) : ExprEvaluatorBaseTy(info), Result(Result) {} bool Success(ArrayRef<APValue> V, const Expr *E) { assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); // FIXME: remove this APValue copy. Result = APValue(V.data(), V.size()); return true; } bool Success(const APValue &V, const Expr *E) { assert(V.isVector()); Result = V; return true; } bool ZeroInitialization(const Expr *E); bool VisitUnaryReal(const UnaryOperator *E) { return Visit(E->getSubExpr()); } bool VisitCastExpr(const CastExpr* E); bool VisitInitListExpr(const InitListExpr *E); bool VisitUnaryImag(const UnaryOperator *E); // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, // binary comparisons, binary and/or/xor, // shufflevector, ExtVectorElementExpr }; } // end anonymous namespace static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); return VectorExprEvaluator(Info, Result).Visit(E); } bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) { const VectorType *VTy = E->getType()->castAs<VectorType>(); unsigned NElts = VTy->getNumElements(); const Expr *SE = E->getSubExpr(); QualType SETy = SE->getType(); switch (E->getCastKind()) { case CK_VectorSplat: { APValue Val = APValue(); if (SETy->isIntegerType()) { APSInt IntResult; if (!EvaluateInteger(SE, IntResult, Info)) return false; Val = APValue(std::move(IntResult)); } else if (SETy->isRealFloatingType()) { APFloat FloatResult(0.0); if (!EvaluateFloat(SE, FloatResult, Info)) return false; Val = APValue(std::move(FloatResult)); } else { return Error(E); } // Splat and create vector APValue. SmallVector<APValue, 4> Elts(NElts, Val); return Success(Elts, E); } case CK_BitCast: { // Evaluate the operand into an APInt we can extract from. llvm::APInt SValInt; if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) return false; // Extract the elements QualType EltTy = VTy->getElementType(); unsigned EltSize = Info.Ctx.getTypeSize(EltTy); bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); SmallVector<APValue, 4> Elts; if (EltTy->isRealFloatingType()) { const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); unsigned FloatEltSize = EltSize; if (&Sem == &APFloat::x87DoubleExtended) FloatEltSize = 80; for (unsigned i = 0; i < NElts; i++) { llvm::APInt Elt; if (BigEndian) Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); else Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); Elts.push_back(APValue(APFloat(Sem, Elt))); } } else if (EltTy->isIntegerType()) { for (unsigned i = 0; i < NElts; i++) { llvm::APInt Elt; if (BigEndian) Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); else Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); } } else { return Error(E); } return Success(Elts, E); } default: return ExprEvaluatorBaseTy::VisitCastExpr(E); } } bool VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { const VectorType *VT = E->getType()->castAs<VectorType>(); unsigned NumInits = E->getNumInits(); unsigned NumElements = VT->getNumElements(); QualType EltTy = VT->getElementType(); SmallVector<APValue, 4> Elements; // The number of initializers can be less than the number of // vector elements. For OpenCL, this can be due to nested vector // initialization. For GCC compatibility, missing trailing elements // should be initialized with zeroes. unsigned CountInits = 0, CountElts = 0; while (CountElts < NumElements) { // Handle nested vector initialization. if (CountInits < NumInits && E->getInit(CountInits)->getType()->isVectorType()) { APValue v; if (!EvaluateVector(E->getInit(CountInits), v, Info)) return Error(E); unsigned vlen = v.getVectorLength(); for (unsigned j = 0; j < vlen; j++) Elements.push_back(v.getVectorElt(j)); CountElts += vlen; } else if (EltTy->isIntegerType()) { llvm::APSInt sInt(32); if (CountInits < NumInits) { if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) return false; } else // trailing integer zero. sInt = Info.Ctx.MakeIntValue(0, EltTy); Elements.push_back(APValue(sInt)); CountElts++; } else { llvm::APFloat f(0.0); if (CountInits < NumInits) { if (!EvaluateFloat(E->getInit(CountInits), f, Info)) return false; } else // trailing float zero. f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); Elements.push_back(APValue(f)); CountElts++; } CountInits++; } return Success(Elements, E); } bool VectorExprEvaluator::ZeroInitialization(const Expr *E) { const VectorType *VT = E->getType()->getAs<VectorType>(); QualType EltTy = VT->getElementType(); APValue ZeroElement; if (EltTy->isIntegerType()) ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); else ZeroElement = APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); return Success(Elements, E); } bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { VisitIgnoredValue(E->getSubExpr()); return ZeroInitialization(E); } //===----------------------------------------------------------------------===// // Array Evaluation //===----------------------------------------------------------------------===// namespace { class ArrayExprEvaluator : public ExprEvaluatorBase<ArrayExprEvaluator> { const LValue &This; APValue &Result; public: ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} bool Success(const APValue &V, const Expr *E) { assert((V.isArray() || V.isLValue()) && "expected array or string literal"); Result = V; return true; } bool ZeroInitialization(const Expr *E) { const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); if (!CAT) return Error(E); Result = APValue(APValue::UninitArray(), 0, CAT->getSize().getZExtValue()); if (!Result.hasArrayFiller()) return true; // Zero-initialize all elements. LValue Subobject = This; Subobject.addArray(Info, E, CAT); ImplicitValueInitExpr VIE(CAT->getElementType()); return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); } bool VisitCallExpr(const CallExpr *E) { return handleCallExpr(E, Result, &This); } bool VisitInitListExpr(const InitListExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E); bool VisitCXXConstructExpr(const CXXConstructExpr *E, const LValue &Subobject, APValue *Value, QualType Type); }; } // end anonymous namespace static bool EvaluateArray(const Expr *E, const LValue &This, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); return ArrayExprEvaluator(Info, This, Result).Visit(E); } bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); if (!CAT) return Error(E); // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] // an appropriately-typed string literal enclosed in braces. if (E->isStringLiteralInit()) { LValue LV; if (!EvaluateLValue(E->getInit(0), LV, Info)) return false; APValue Val; LV.moveInto(Val); return Success(Val, E); } bool Success = true; assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && "zero-initialized array shouldn't have any initialized elts"); APValue Filler; if (Result.isArray() && Result.hasArrayFiller()) Filler = Result.getArrayFiller(); unsigned NumEltsToInit = E->getNumInits(); unsigned NumElts = CAT->getSize().getZExtValue(); const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr; // If the initializer might depend on the array index, run it for each // array element. For now, just whitelist non-class value-initialization. if (NumEltsToInit != NumElts && !isa<ImplicitValueInitExpr>(FillerExpr)) NumEltsToInit = NumElts; Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); // If the array was previously zero-initialized, preserve the // zero-initialized values. if (!Filler.isUninit()) { for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) Result.getArrayInitializedElt(I) = Filler; if (Result.hasArrayFiller()) Result.getArrayFiller() = Filler; } LValue Subobject = This; Subobject.addArray(Info, E, CAT); for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { const Expr *Init = Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), Info, Subobject, Init) || !HandleLValueArrayAdjustment(Info, Init, Subobject, CAT->getElementType(), 1)) { if (!Info.noteFailure()) return false; Success = false; } } if (!Result.hasArrayFiller()) return Success; // If we get here, we have a trivial filler, which we can just evaluate // once and splat over the rest of the array elements. assert(FillerExpr && "no array filler for incomplete init list"); return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, FillerExpr) && Success; } bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { return VisitCXXConstructExpr(E, This, &Result, E->getType()); } bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, const LValue &Subobject, APValue *Value, QualType Type) { bool HadZeroInit = !Value->isUninit(); if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { unsigned N = CAT->getSize().getZExtValue(); // Preserve the array filler if we had prior zero-initialization. APValue Filler = HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() : APValue(); *Value = APValue(APValue::UninitArray(), N, N); if (HadZeroInit) for (unsigned I = 0; I != N; ++I) Value->getArrayInitializedElt(I) = Filler; // Initialize the elements. LValue ArrayElt = Subobject; ArrayElt.addArray(Info, E, CAT); for (unsigned I = 0; I != N; ++I) if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), CAT->getElementType()) || !HandleLValueArrayAdjustment(Info, E, ArrayElt, CAT->getElementType(), 1)) return false; return true; } if (!Type->isRecordType()) return Error(E); return RecordExprEvaluator(Info, Subobject, *Value) .VisitCXXConstructExpr(E, Type); } //===----------------------------------------------------------------------===// // Integer Evaluation // // As a GNU extension, we support casting pointers to sufficiently-wide integer // types and back in constant folding. Integer values are thus represented // either as an integer-valued APValue, or as an lvalue-valued APValue. //===----------------------------------------------------------------------===// namespace { class IntExprEvaluator : public ExprEvaluatorBase<IntExprEvaluator> { APValue &Result; public: IntExprEvaluator(EvalInfo &info, APValue &result) : ExprEvaluatorBaseTy(info), Result(result) {} bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { assert(E->getType()->isIntegralOrEnumerationType() && "Invalid evaluation result."); assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && "Invalid evaluation result."); assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && "Invalid evaluation result."); Result = APValue(SI); return true; } bool Success(const llvm::APSInt &SI, const Expr *E) { return Success(SI, E, Result); } bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { assert(E->getType()->isIntegralOrEnumerationType() && "Invalid evaluation result."); assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && "Invalid evaluation result."); Result = APValue(APSInt(I)); Result.getInt().setIsUnsigned( E->getType()->isUnsignedIntegerOrEnumerationType()); return true; } bool Success(const llvm::APInt &I, const Expr *E) { return Success(I, E, Result); } bool Success(uint64_t Value, const Expr *E, APValue &Result) { assert(E->getType()->isIntegralOrEnumerationType() && "Invalid evaluation result."); Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); return true; } bool Success(uint64_t Value, const Expr *E) { return Success(Value, E, Result); } bool Success(CharUnits Size, const Expr *E) { return Success(Size.getQuantity(), E); } bool Success(const APValue &V, const Expr *E) { if (V.isLValue() || V.isAddrLabelDiff()) { Result = V; return true; } return Success(V.getInt(), E); } bool ZeroInitialization(const Expr *E) { return Success(0, E); } //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// bool VisitIntegerLiteral(const IntegerLiteral *E) { return Success(E->getValue(), E); } bool VisitCharacterLiteral(const CharacterLiteral *E) { return Success(E->getValue(), E); } bool CheckReferencedDecl(const Expr *E, const Decl *D); bool VisitDeclRefExpr(const DeclRefExpr *E) { if (CheckReferencedDecl(E, E->getDecl())) return true; return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); } bool VisitMemberExpr(const MemberExpr *E) { if (CheckReferencedDecl(E, E->getMemberDecl())) { VisitIgnoredBaseExpression(E->getBase()); return true; } return ExprEvaluatorBaseTy::VisitMemberExpr(E); } bool VisitCallExpr(const CallExpr *E); bool VisitBinaryOperator(const BinaryOperator *E); bool VisitOffsetOfExpr(const OffsetOfExpr *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitCastExpr(const CastExpr* E); bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { return Success(E->getValue(), E); } bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { return Success(E->getValue(), E); } // Note, GNU defines __null as an integer, not a pointer. bool VisitGNUNullExpr(const GNUNullExpr *E) { return ZeroInitialization(E); } bool VisitTypeTraitExpr(const TypeTraitExpr *E) { return Success(E->getValue(), E); } bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { return Success(E->getValue(), E); } bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { return Success(E->getValue(), E); } bool VisitUnaryReal(const UnaryOperator *E); bool VisitUnaryImag(const UnaryOperator *E); bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); private: bool TryEvaluateBuiltinObjectSize(const CallExpr *E, unsigned Type); // FIXME: Missing: array subscript of vector, member of vector }; } // end anonymous namespace /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and /// produce either the integer value or a pointer. /// /// GCC has a heinous extension which folds casts between pointer types and /// pointer-sized integral types. We support this by allowing the evaluation of /// an integer rvalue to produce a pointer (represented as an lvalue) instead. /// Some simple arithmetic on such values is supported (they are treated much /// like char*). static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); return IntExprEvaluator(Info, Result).Visit(E); } static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { APValue Val; if (!EvaluateIntegerOrLValue(E, Val, Info)) return false; if (!Val.isInt()) { // FIXME: It would be better to produce the diagnostic for casting // a pointer to an integer. Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } Result = Val.getInt(); return true; } /// Check whether the given declaration can be directly converted to an integral /// rvalue. If not, no diagnostic is produced; there are other things we can /// try. bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { // Enums are integer constant exprs. if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { // Check for signedness/width mismatches between E type and ECD value. bool SameSign = (ECD->getInitVal().isSigned() == E->getType()->isSignedIntegerOrEnumerationType()); bool SameWidth = (ECD->getInitVal().getBitWidth() == Info.Ctx.getIntWidth(E->getType())); if (SameSign && SameWidth) return Success(ECD->getInitVal(), E); else { // Get rid of mismatch (otherwise Success assertions will fail) // by computing a new value matching the type of E. llvm::APSInt Val = ECD->getInitVal(); if (!SameSign) Val.setIsSigned(!ECD->getInitVal().isSigned()); if (!SameWidth) Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); return Success(Val, E); } } return false; } /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way /// as GCC. static int EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) { // The following enum mimics the values returned by GCC. // FIXME: Does GCC differ between lvalue and rvalue references here? enum gcc_type_class { no_type_class = -1, void_type_class, integer_type_class, char_type_class, enumeral_type_class, boolean_type_class, pointer_type_class, reference_type_class, offset_type_class, real_type_class, complex_type_class, function_type_class, method_type_class, record_type_class, union_type_class, array_type_class, string_type_class, lang_type_class }; // If no argument was supplied, default to "no_type_class". This isn't // ideal, however it is what gcc does. if (E->getNumArgs() == 0) return no_type_class; QualType CanTy = E->getArg(0)->getType().getCanonicalType(); const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy); switch (CanTy->getTypeClass()) { #define TYPE(ID, BASE) #define DEPENDENT_TYPE(ID, BASE) case Type::ID: #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID: #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID: #include "clang/AST/TypeNodes.def" llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); case Type::Builtin: switch (BT->getKind()) { #define BUILTIN_TYPE(ID, SINGLETON_ID) #define SIGNED_TYPE(ID, SINGLETON_ID) case BuiltinType::ID: return integer_type_class; #define FLOATING_TYPE(ID, SINGLETON_ID) case BuiltinType::ID: return real_type_class; #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) case BuiltinType::ID: break; #include "clang/AST/BuiltinTypes.def" case BuiltinType::Void: return void_type_class; case BuiltinType::Bool: return boolean_type_class; case BuiltinType::Char_U: // gcc doesn't appear to use char_type_class case BuiltinType::UChar: case BuiltinType::UShort: case BuiltinType::UInt: case BuiltinType::ULong: case BuiltinType::ULongLong: case BuiltinType::UInt128: return integer_type_class; case BuiltinType::NullPtr: return pointer_type_class; case BuiltinType::WChar_U: case BuiltinType::Char16: case BuiltinType::Char32: case BuiltinType::ObjCId: case BuiltinType::ObjCClass: case BuiltinType::ObjCSel: #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \ case BuiltinType::Id: #include "clang/Basic/OpenCLImageTypes.def" case BuiltinType::OCLSampler: case BuiltinType::OCLEvent: case BuiltinType::OCLClkEvent: case BuiltinType::OCLQueue: case BuiltinType::OCLNDRange: case BuiltinType::OCLReserveID: case BuiltinType::Dependent: llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); }; case Type::Enum: return LangOpts.CPlusPlus ? enumeral_type_class : integer_type_class; break; case Type::Pointer: return pointer_type_class; break; case Type::MemberPointer: if (CanTy->isMemberDataPointerType()) return offset_type_class; else { // We expect member pointers to be either data or function pointers, // nothing else. assert(CanTy->isMemberFunctionPointerType()); return method_type_class; } case Type::Complex: return complex_type_class; case Type::FunctionNoProto: case Type::FunctionProto: return LangOpts.CPlusPlus ? function_type_class : pointer_type_class; case Type::Record: if (const RecordType *RT = CanTy->getAs<RecordType>()) { switch (RT->getDecl()->getTagKind()) { case TagTypeKind::TTK_Struct: case TagTypeKind::TTK_Class: case TagTypeKind::TTK_Interface: return record_type_class; case TagTypeKind::TTK_Enum: return LangOpts.CPlusPlus ? enumeral_type_class : integer_type_class; case TagTypeKind::TTK_Union: return union_type_class; } } llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); case Type::ConstantArray: case Type::VariableArray: case Type::IncompleteArray: return LangOpts.CPlusPlus ? array_type_class : pointer_type_class; case Type::BlockPointer: case Type::LValueReference: case Type::RValueReference: case Type::Vector: case Type::ExtVector: case Type::Auto: case Type::ObjCObject: case Type::ObjCInterface: case Type::ObjCObjectPointer: case Type::Pipe: case Type::Atomic: llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); } llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); } /// EvaluateBuiltinConstantPForLValue - Determine the result of /// __builtin_constant_p when applied to the given lvalue. /// /// An lvalue is only "constant" if it is a pointer or reference to the first /// character of a string literal. template<typename LValue> static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) { const Expr *E = LV.getLValueBase().template dyn_cast<const Expr*>(); return E && isa<StringLiteral>(E) && LV.getLValueOffset().isZero(); } /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to /// GCC as we can manage. static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) { QualType ArgType = Arg->getType(); // __builtin_constant_p always has one operand. The rules which gcc follows // are not precisely documented, but are as follows: // // - If the operand is of integral, floating, complex or enumeration type, // and can be folded to a known value of that type, it returns 1. // - If the operand and can be folded to a pointer to the first character // of a string literal (or such a pointer cast to an integral type), it // returns 1. // // Otherwise, it returns 0. // // FIXME: GCC also intends to return 1 for literals of aggregate types, but // its support for this does not currently work. if (ArgType->isIntegralOrEnumerationType()) { Expr::EvalResult Result; if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects) return false; APValue &V = Result.Val; if (V.getKind() == APValue::Int) return true; if (V.getKind() == APValue::LValue) return EvaluateBuiltinConstantPForLValue(V); } else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) { return Arg->isEvaluatable(Ctx); } else if (ArgType->isPointerType() || Arg->isGLValue()) { LValue LV; Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info) : EvaluatePointer(Arg, LV, Info)) && !Status.HasSideEffects) return EvaluateBuiltinConstantPForLValue(LV); } // Anything else isn't considered to be sufficiently constant. return false; } /// Retrieves the "underlying object type" of the given expression, /// as used by __builtin_object_size. static QualType getObjectType(APValue::LValueBase B) { if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { if (const VarDecl *VD = dyn_cast<VarDecl>(D)) return VD->getType(); } else if (const Expr *E = B.get<const Expr*>()) { if (isa<CompoundLiteralExpr>(E)) return E->getType(); } return QualType(); } /// A more selective version of E->IgnoreParenCasts for /// TryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only /// to change the type of E. /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo` /// /// Always returns an RValue with a pointer representation. static const Expr *ignorePointerCastsAndParens(const Expr *E) { assert(E->isRValue() && E->getType()->hasPointerRepresentation()); auto *NoParens = E->IgnoreParens(); auto *Cast = dyn_cast<CastExpr>(NoParens); if (Cast == nullptr) return NoParens; // We only conservatively allow a few kinds of casts, because this code is // inherently a simple solution that seeks to support the common case. auto CastKind = Cast->getCastKind(); if (CastKind != CK_NoOp && CastKind != CK_BitCast && CastKind != CK_AddressSpaceConversion) return NoParens; auto *SubExpr = Cast->getSubExpr(); if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isRValue()) return NoParens; return ignorePointerCastsAndParens(SubExpr); } /// Checks to see if the given LValue's Designator is at the end of the LValue's /// record layout. e.g. /// struct { struct { int a, b; } fst, snd; } obj; /// obj.fst // no /// obj.snd // yes /// obj.fst.a // no /// obj.fst.b // no /// obj.snd.a // no /// obj.snd.b // yes /// /// Please note: this function is specialized for how __builtin_object_size /// views "objects". /// /// If this encounters an invalid RecordDecl, it will always return true. static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) { assert(!LVal.Designator.Invalid); auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) { const RecordDecl *Parent = FD->getParent(); Invalid = Parent->isInvalidDecl(); if (Invalid || Parent->isUnion()) return true; const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent); return FD->getFieldIndex() + 1 == Layout.getFieldCount(); }; auto &Base = LVal.getLValueBase(); if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) { if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) { bool Invalid; if (!IsLastOrInvalidFieldDecl(FD, Invalid)) return Invalid; } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) { for (auto *FD : IFD->chain()) { bool Invalid; if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid)) return Invalid; } } } QualType BaseType = getType(Base); for (int I = 0, E = LVal.Designator.Entries.size(); I != E; ++I) { if (BaseType->isArrayType()) { // Because __builtin_object_size treats arrays as objects, we can ignore // the index iff this is the last array in the Designator. if (I + 1 == E) return true; auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType)); uint64_t Index = LVal.Designator.Entries[I].ArrayIndex; if (Index + 1 != CAT->getSize()) return false; BaseType = CAT->getElementType(); } else if (BaseType->isAnyComplexType()) { auto *CT = BaseType->castAs<ComplexType>(); uint64_t Index = LVal.Designator.Entries[I].ArrayIndex; if (Index != 1) return false; BaseType = CT->getElementType(); } else if (auto *FD = getAsField(LVal.Designator.Entries[I])) { bool Invalid; if (!IsLastOrInvalidFieldDecl(FD, Invalid)) return Invalid; BaseType = FD->getType(); } else { assert(getAsBaseClass(LVal.Designator.Entries[I]) != nullptr && "Expecting cast to a base class"); return false; } } return true; } /// Tests to see if the LValue has a designator (that isn't necessarily valid). static bool refersToCompleteObject(const LValue &LVal) { if (LVal.Designator.Invalid || !LVal.Designator.Entries.empty()) return false; if (!LVal.InvalidBase) return true; auto *E = LVal.Base.dyn_cast<const Expr *>(); (void)E; assert(E != nullptr && isa<MemberExpr>(E)); return false; } /// Tries to evaluate the __builtin_object_size for @p E. If successful, returns /// true and stores the result in @p Size. /// /// If @p WasError is non-null, this will report whether the failure to evaluate /// is to be treated as an Error in IntExprEvaluator. static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type, EvalInfo &Info, uint64_t &Size, bool *WasError = nullptr) { if (WasError != nullptr) *WasError = false; auto Error = [&](const Expr *E) { if (WasError != nullptr) *WasError = true; return false; }; auto Success = [&](uint64_t S, const Expr *E) { Size = S; return true; }; // Determine the denoted object. LValue Base; { // The operand of __builtin_object_size is never evaluated for side-effects. // If there are any, but we can determine the pointed-to object anyway, then // ignore the side-effects. SpeculativeEvaluationRAII SpeculativeEval(Info); FoldOffsetRAII Fold(Info, Type & 1); if (E->isGLValue()) { // It's possible for us to be given GLValues if we're called via // Expr::tryEvaluateObjectSize. APValue RVal; if (!EvaluateAsRValue(Info, E, RVal)) return false; Base.setFrom(Info.Ctx, RVal); } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), Base, Info)) return false; } CharUnits BaseOffset = Base.getLValueOffset(); // If we point to before the start of the object, there are no accessible // bytes. if (BaseOffset.isNegative()) return Success(0, E); // In the case where we're not dealing with a subobject, we discard the // subobject bit. bool SubobjectOnly = (Type & 1) != 0 && !refersToCompleteObject(Base); // If Type & 1 is 0, we need to be able to statically guarantee that the bytes // exist. If we can't verify the base, then we can't do that. // // As a special case, we produce a valid object size for an unknown object // with a known designator if Type & 1 is 1. For instance: // // extern struct X { char buff[32]; int a, b, c; } *p; // int a = __builtin_object_size(p->buff + 4, 3); // returns 28 // int b = __builtin_object_size(p->buff + 4, 2); // returns 0, not 40 // // This matches GCC's behavior. if (Base.InvalidBase && !SubobjectOnly) return Error(E); // If we're not examining only the subobject, then we reset to a complete // object designator // // If Type is 1 and we've lost track of the subobject, just find the complete // object instead. (If Type is 3, that's not correct behavior and we should // return 0 instead.) LValue End = Base; if (!SubobjectOnly || (End.Designator.Invalid && Type == 1)) { QualType T = getObjectType(End.getLValueBase()); if (T.isNull()) End.Designator.setInvalid(); else { End.Designator = SubobjectDesignator(T); End.Offset = CharUnits::Zero(); } } // If it is not possible to determine which objects ptr points to at compile // time, __builtin_object_size should return (size_t) -1 for type 0 or 1 // and (size_t) 0 for type 2 or 3. if (End.Designator.Invalid) return false; // According to the GCC documentation, we want the size of the subobject // denoted by the pointer. But that's not quite right -- what we actually // want is the size of the immediately-enclosing array, if there is one. int64_t AmountToAdd = 1; if (End.Designator.MostDerivedIsArrayElement && End.Designator.Entries.size() == End.Designator.MostDerivedPathLength) { // We got a pointer to an array. Step to its end. AmountToAdd = End.Designator.MostDerivedArraySize - End.Designator.Entries.back().ArrayIndex; } else if (End.Designator.isOnePastTheEnd()) { // We're already pointing at the end of the object. AmountToAdd = 0; } QualType PointeeType = End.Designator.MostDerivedType; assert(!PointeeType.isNull()); if (PointeeType->isIncompleteType() || PointeeType->isFunctionType()) return Error(E); if (!HandleLValueArrayAdjustment(Info, E, End, End.Designator.MostDerivedType, AmountToAdd)) return false; auto EndOffset = End.getLValueOffset(); // The following is a moderately common idiom in C: // // struct Foo { int a; char c[1]; }; // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar)); // strcpy(&F->c[0], Bar); // // So, if we see that we're examining a 1-length (or 0-length) array at the // end of a struct with an unknown base, we give up instead of breaking code // that behaves this way. Note that we only do this when Type=1, because // Type=3 is a lower bound, so answering conservatively is fine. if (End.InvalidBase && SubobjectOnly && Type == 1 && End.Designator.Entries.size() == End.Designator.MostDerivedPathLength && End.Designator.MostDerivedIsArrayElement && End.Designator.MostDerivedArraySize < 2 && isDesignatorAtObjectEnd(Info.Ctx, End)) return false; if (BaseOffset > EndOffset) return Success(0, E); return Success((EndOffset - BaseOffset).getQuantity(), E); } bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E, unsigned Type) { uint64_t Size; bool WasError; if (::tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size, &WasError)) return Success(Size, E); if (WasError) return Error(E); return false; } bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { switch (unsigned BuiltinOp = E->getBuiltinCallee()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__builtin_object_size: { // The type was checked when we built the expression. unsigned Type = E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); assert(Type <= 3 && "unexpected type"); if (TryEvaluateBuiltinObjectSize(E, Type)) return true; if (E->getArg(0)->HasSideEffects(Info.Ctx)) return Success((Type & 2) ? 0 : -1, E); // Expression had no side effects, but we couldn't statically determine the // size of the referenced object. switch (Info.EvalMode) { case EvalInfo::EM_ConstantExpression: case EvalInfo::EM_PotentialConstantExpression: case EvalInfo::EM_ConstantFold: case EvalInfo::EM_EvaluateForOverflow: case EvalInfo::EM_IgnoreSideEffects: case EvalInfo::EM_DesignatorFold: // Leave it to IR generation. return Error(E); case EvalInfo::EM_ConstantExpressionUnevaluated: case EvalInfo::EM_PotentialConstantExpressionUnevaluated: // Reduce it to a constant now. return Success((Type & 2) ? 0 : -1, E); } } case Builtin::BI__builtin_bswap16: case Builtin::BI__builtin_bswap32: case Builtin::BI__builtin_bswap64: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.byteSwap(), E); } case Builtin::BI__builtin_classify_type: return Success(EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E); // FIXME: BI__builtin_clrsb // FIXME: BI__builtin_clrsbl // FIXME: BI__builtin_clrsbll case Builtin::BI__builtin_clz: case Builtin::BI__builtin_clzl: case Builtin::BI__builtin_clzll: case Builtin::BI__builtin_clzs: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; if (!Val) return Error(E); return Success(Val.countLeadingZeros(), E); } case Builtin::BI__builtin_constant_p: return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), E); case Builtin::BI__builtin_ctz: case Builtin::BI__builtin_ctzl: case Builtin::BI__builtin_ctzll: case Builtin::BI__builtin_ctzs: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; if (!Val) return Error(E); return Success(Val.countTrailingZeros(), E); } case Builtin::BI__builtin_eh_return_data_regno: { int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); return Success(Operand, E); } case Builtin::BI__builtin_expect: return Visit(E->getArg(0)); case Builtin::BI__builtin_ffs: case Builtin::BI__builtin_ffsl: case Builtin::BI__builtin_ffsll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; unsigned N = Val.countTrailingZeros(); return Success(N == Val.getBitWidth() ? 0 : N + 1, E); } case Builtin::BI__builtin_fpclassify: { APFloat Val(0.0); if (!EvaluateFloat(E->getArg(5), Val, Info)) return false; unsigned Arg; switch (Val.getCategory()) { case APFloat::fcNaN: Arg = 0; break; case APFloat::fcInfinity: Arg = 1; break; case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; case APFloat::fcZero: Arg = 4; break; } return Visit(E->getArg(Arg)); } case Builtin::BI__builtin_isinf_sign: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); } case Builtin::BI__builtin_isinf: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isInfinity() ? 1 : 0, E); } case Builtin::BI__builtin_isfinite: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isFinite() ? 1 : 0, E); } case Builtin::BI__builtin_isnan: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isNaN() ? 1 : 0, E); } case Builtin::BI__builtin_isnormal: { APFloat Val(0.0); return EvaluateFloat(E->getArg(0), Val, Info) && Success(Val.isNormal() ? 1 : 0, E); } case Builtin::BI__builtin_parity: case Builtin::BI__builtin_parityl: case Builtin::BI__builtin_parityll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.countPopulation() % 2, E); } case Builtin::BI__builtin_popcount: case Builtin::BI__builtin_popcountl: case Builtin::BI__builtin_popcountll: { APSInt Val; if (!EvaluateInteger(E->getArg(0), Val, Info)) return false; return Success(Val.countPopulation(), E); } case Builtin::BIstrlen: // A call to strlen is not a constant expression. if (Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_invalid_function) << /*isConstexpr*/0 << /*isConstructor*/0 << "'strlen'"; else Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); // Fall through. case Builtin::BI__builtin_strlen: { // As an extension, we support __builtin_strlen() as a constant expression, // and support folding strlen() to a constant. LValue String; if (!EvaluatePointer(E->getArg(0), String, Info)) return false; // Fast path: if it's a string literal, search the string value. if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>( String.getLValueBase().dyn_cast<const Expr *>())) { // The string literal may have embedded null characters. Find the first // one and truncate there. StringRef Str = S->getBytes(); int64_t Off = String.Offset.getQuantity(); if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && S->getCharByteWidth() == 1) { Str = Str.substr(Off); StringRef::size_type Pos = Str.find(0); if (Pos != StringRef::npos) Str = Str.substr(0, Pos); return Success(Str.size(), E); } // Fall through to slow path to issue appropriate diagnostic. } // Slow path: scan the bytes of the string looking for the terminating 0. QualType CharTy = E->getArg(0)->getType()->getPointeeType(); for (uint64_t Strlen = 0; /**/; ++Strlen) { APValue Char; if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || !Char.isInt()) return false; if (!Char.getInt()) return Success(Strlen, E); if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) return false; } } case Builtin::BI__atomic_always_lock_free: case Builtin::BI__atomic_is_lock_free: case Builtin::BI__c11_atomic_is_lock_free: { APSInt SizeVal; if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) return false; // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power // of two less than the maximum inline atomic width, we know it is // lock-free. If the size isn't a power of two, or greater than the // maximum alignment where we promote atomics, we know it is not lock-free // (at least not in the sense of atomic_is_lock_free). Otherwise, // the answer can only be determined at runtime; for example, 16-byte // atomics have lock-free implementations on some, but not all, // x86-64 processors. // Check power-of-two. CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); if (Size.isPowerOfTwo()) { // Check against inlining width. unsigned InlineWidthBits = Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || Size == CharUnits::One() || E->getArg(1)->isNullPointerConstant(Info.Ctx, Expr::NPC_NeverValueDependent)) // OK, we will inline appropriately-aligned operations of this size, // and _Atomic(T) is appropriately-aligned. return Success(1, E); QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> castAs<PointerType>()->getPointeeType(); if (!PointeeType->isIncompleteType() && Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { // OK, we will inline operations on this object. return Success(1, E); } } } return BuiltinOp == Builtin::BI__atomic_always_lock_free ? Success(0, E) : Error(E); } } } static bool HasSameBase(const LValue &A, const LValue &B) { if (!A.getLValueBase()) return !B.getLValueBase(); if (!B.getLValueBase()) return false; if (A.getLValueBase().getOpaqueValue() != B.getLValueBase().getOpaqueValue()) { const Decl *ADecl = GetLValueBaseDecl(A); if (!ADecl) return false; const Decl *BDecl = GetLValueBaseDecl(B); if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) return false; } return IsGlobalLValue(A.getLValueBase()) || A.getLValueCallIndex() == B.getLValueCallIndex(); } /// \brief Determine whether this is a pointer past the end of the complete /// object referred to by the lvalue. static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx, const LValue &LV) { // A null pointer can be viewed as being "past the end" but we don't // choose to look at it that way here. if (!LV.getLValueBase()) return false; // If the designator is valid and refers to a subobject, we're not pointing // past the end. if (!LV.getLValueDesignator().Invalid && !LV.getLValueDesignator().isOnePastTheEnd()) return false; // A pointer to an incomplete type might be past-the-end if the type's size is // zero. We cannot tell because the type is incomplete. QualType Ty = getType(LV.getLValueBase()); if (Ty->isIncompleteType()) return true; // We're a past-the-end pointer if we point to the byte after the object, // no matter what our type or path is. auto Size = Ctx.getTypeSizeInChars(Ty); return LV.getLValueOffset() == Size; } namespace { /// \brief Data recursive integer evaluator of certain binary operators. /// /// We use a data recursive algorithm for binary operators so that we are able /// to handle extreme cases of chained binary operators without causing stack /// overflow. class DataRecursiveIntBinOpEvaluator { struct EvalResult { APValue Val; bool Failed; EvalResult() : Failed(false) { } void swap(EvalResult &RHS) { Val.swap(RHS.Val); Failed = RHS.Failed; RHS.Failed = false; } }; struct Job { const Expr *E; EvalResult LHSResult; // meaningful only for binary operator expression. enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; Job() = default; Job(Job &&J) : E(J.E), LHSResult(J.LHSResult), Kind(J.Kind), SpecEvalRAII(std::move(J.SpecEvalRAII)) {} void startSpeculativeEval(EvalInfo &Info) { SpecEvalRAII = SpeculativeEvaluationRAII(Info); } private: SpeculativeEvaluationRAII SpecEvalRAII; }; SmallVector<Job, 16> Queue; IntExprEvaluator &IntEval; EvalInfo &Info; APValue &FinalResult; public: DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } /// \brief True if \param E is a binary operator that we are going to handle /// data recursively. /// We handle binary operators that are comma, logical, or that have operands /// with integral or enumeration type. static bool shouldEnqueue(const BinaryOperator *E) { return E->getOpcode() == BO_Comma || E->isLogicalOp() || (E->isRValue() && E->getType()->isIntegralOrEnumerationType() && E->getLHS()->getType()->isIntegralOrEnumerationType() && E->getRHS()->getType()->isIntegralOrEnumerationType()); } bool Traverse(const BinaryOperator *E) { enqueue(E); EvalResult PrevResult; while (!Queue.empty()) process(PrevResult); if (PrevResult.Failed) return false; FinalResult.swap(PrevResult.Val); return true; } private: bool Success(uint64_t Value, const Expr *E, APValue &Result) { return IntEval.Success(Value, E, Result); } bool Success(const APSInt &Value, const Expr *E, APValue &Result) { return IntEval.Success(Value, E, Result); } bool Error(const Expr *E) { return IntEval.Error(E); } bool Error(const Expr *E, diag::kind D) { return IntEval.Error(E, D); } OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { return Info.CCEDiag(E, D); } // \brief Returns true if visiting the RHS is necessary, false otherwise. bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, bool &SuppressRHSDiags); bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, const BinaryOperator *E, APValue &Result); void EvaluateExpr(const Expr *E, EvalResult &Result) { Result.Failed = !Evaluate(Result.Val, Info, E); if (Result.Failed) Result.Val = APValue(); } void process(EvalResult &Result); void enqueue(const Expr *E) { E = E->IgnoreParens(); Queue.resize(Queue.size()+1); Queue.back().E = E; Queue.back().Kind = Job::AnyExprKind; } }; } bool DataRecursiveIntBinOpEvaluator:: VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, bool &SuppressRHSDiags) { if (E->getOpcode() == BO_Comma) { // Ignore LHS but note if we could not evaluate it. if (LHSResult.Failed) return Info.noteSideEffect(); return true; } if (E->isLogicalOp()) { bool LHSAsBool; if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { // We were able to evaluate the LHS, see if we can get away with not // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 if (LHSAsBool == (E->getOpcode() == BO_LOr)) { Success(LHSAsBool, E, LHSResult.Val); return false; // Ignore RHS } } else { LHSResult.Failed = true; // Since we weren't able to evaluate the left hand side, it // might have had side effects. if (!Info.noteSideEffect()) return false; // We can't evaluate the LHS; however, sometimes the result // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. // Don't ignore RHS and suppress diagnostics from this arm. SuppressRHSDiags = true; } return true; } assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && E->getRHS()->getType()->isIntegralOrEnumerationType()); if (LHSResult.Failed && !Info.noteFailure()) return false; // Ignore RHS; return true; } bool DataRecursiveIntBinOpEvaluator:: VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, const BinaryOperator *E, APValue &Result) { if (E->getOpcode() == BO_Comma) { if (RHSResult.Failed) return false; Result = RHSResult.Val; return true; } if (E->isLogicalOp()) { bool lhsResult, rhsResult; bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); if (LHSIsOK) { if (RHSIsOK) { if (E->getOpcode() == BO_LOr) return Success(lhsResult || rhsResult, E, Result); else return Success(lhsResult && rhsResult, E, Result); } } else { if (RHSIsOK) { // We can't evaluate the LHS; however, sometimes the result // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. if (rhsResult == (E->getOpcode() == BO_LOr)) return Success(rhsResult, E, Result); } } return false; } assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && E->getRHS()->getType()->isIntegralOrEnumerationType()); if (LHSResult.Failed || RHSResult.Failed) return false; const APValue &LHSVal = LHSResult.Val; const APValue &RHSVal = RHSResult.Val; // Handle cases like (unsigned long)&a + 4. if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { Result = LHSVal; CharUnits AdditionalOffset = CharUnits::fromQuantity(RHSVal.getInt().getZExtValue()); if (E->getOpcode() == BO_Add) Result.getLValueOffset() += AdditionalOffset; else Result.getLValueOffset() -= AdditionalOffset; return true; } // Handle cases like 4 + (unsigned long)&a if (E->getOpcode() == BO_Add && RHSVal.isLValue() && LHSVal.isInt()) { Result = RHSVal; Result.getLValueOffset() += CharUnits::fromQuantity(LHSVal.getInt().getZExtValue()); return true; } if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { // Handle (intptr_t)&&A - (intptr_t)&&B. if (!LHSVal.getLValueOffset().isZero() || !RHSVal.getLValueOffset().isZero()) return false; const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); if (!LHSExpr || !RHSExpr) return false; const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); if (!LHSAddrExpr || !RHSAddrExpr) return false; // Make sure both labels come from the same function. if (LHSAddrExpr->getLabel()->getDeclContext() != RHSAddrExpr->getLabel()->getDeclContext()) return false; Result = APValue(LHSAddrExpr, RHSAddrExpr); return true; } // All the remaining cases expect both operands to be an integer if (!LHSVal.isInt() || !RHSVal.isInt()) return Error(E); // Set up the width and signedness manually, in case it can't be deduced // from the operation we're performing. // FIXME: Don't do this in the cases where we can deduce it. APSInt Value(Info.Ctx.getIntWidth(E->getType()), E->getType()->isUnsignedIntegerOrEnumerationType()); if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), RHSVal.getInt(), Value)) return false; return Success(Value, E, Result); } void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { Job &job = Queue.back(); switch (job.Kind) { case Job::AnyExprKind: { if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { if (shouldEnqueue(Bop)) { job.Kind = Job::BinOpKind; enqueue(Bop->getLHS()); return; } } EvaluateExpr(job.E, Result); Queue.pop_back(); return; } case Job::BinOpKind: { const BinaryOperator *Bop = cast<BinaryOperator>(job.E); bool SuppressRHSDiags = false; if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { Queue.pop_back(); return; } if (SuppressRHSDiags) job.startSpeculativeEval(Info); job.LHSResult.swap(Result); job.Kind = Job::BinOpVisitedLHSKind; enqueue(Bop->getRHS()); return; } case Job::BinOpVisitedLHSKind: { const BinaryOperator *Bop = cast<BinaryOperator>(job.E); EvalResult RHS; RHS.swap(Result); Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); Queue.pop_back(); return; } } llvm_unreachable("Invalid Job::Kind!"); } namespace { /// Used when we determine that we should fail, but can keep evaluating prior to /// noting that we had a failure. class DelayedNoteFailureRAII { EvalInfo &Info; bool NoteFailure; public: DelayedNoteFailureRAII(EvalInfo &Info, bool NoteFailure = true) : Info(Info), NoteFailure(NoteFailure) {} ~DelayedNoteFailureRAII() { if (NoteFailure) { bool ContinueAfterFailure = Info.noteFailure(); (void)ContinueAfterFailure; assert(ContinueAfterFailure && "Shouldn't have kept evaluating on failure."); } } }; } bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { // We don't call noteFailure immediately because the assignment happens after // we evaluate LHS and RHS. if (!Info.keepEvaluatingAfterFailure() && E->isAssignmentOp()) return Error(E); DelayedNoteFailureRAII MaybeNoteFailureLater(Info, E->isAssignmentOp()); if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); QualType LHSTy = E->getLHS()->getType(); QualType RHSTy = E->getRHS()->getType(); if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) { ComplexValue LHS, RHS; bool LHSOK; if (E->isAssignmentOp()) { LValue LV; EvaluateLValue(E->getLHS(), LV, Info); LHSOK = false; } else if (LHSTy->isRealFloatingType()) { LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info); if (LHSOK) { LHS.makeComplexFloat(); LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics()); } } else { LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); } if (!LHSOK && !Info.noteFailure()) return false; if (E->getRHS()->getType()->isRealFloatingType()) { if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK) return false; RHS.makeComplexFloat(); RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics()); } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) return false; if (LHS.isComplexFloat()) { APFloat::cmpResult CR_r = LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); APFloat::cmpResult CR_i = LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); if (E->getOpcode() == BO_EQ) return Success((CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual), E); else { assert(E->getOpcode() == BO_NE && "Invalid complex comparison."); return Success(((CR_r == APFloat::cmpGreaterThan || CR_r == APFloat::cmpLessThan || CR_r == APFloat::cmpUnordered) || (CR_i == APFloat::cmpGreaterThan || CR_i == APFloat::cmpLessThan || CR_i == APFloat::cmpUnordered)), E); } } else { if (E->getOpcode() == BO_EQ) return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() && LHS.getComplexIntImag() == RHS.getComplexIntImag()), E); else { assert(E->getOpcode() == BO_NE && "Invalid compex comparison."); return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() || LHS.getComplexIntImag() != RHS.getComplexIntImag()), E); } } } if (LHSTy->isRealFloatingType() && RHSTy->isRealFloatingType()) { APFloat RHS(0.0), LHS(0.0); bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) return false; APFloat::cmpResult CR = LHS.compare(RHS); switch (E->getOpcode()) { default: llvm_unreachable("Invalid binary operator!"); case BO_LT: return Success(CR == APFloat::cmpLessThan, E); case BO_GT: return Success(CR == APFloat::cmpGreaterThan, E); case BO_LE: return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E); case BO_GE: return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, E); case BO_EQ: return Success(CR == APFloat::cmpEqual, E); case BO_NE: return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpLessThan || CR == APFloat::cmpUnordered, E); } } if (LHSTy->isPointerType() && RHSTy->isPointerType()) { if (E->getOpcode() == BO_Sub || E->isComparisonOp()) { LValue LHSValue, RHSValue; bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) return false; // Reject differing bases from the normal codepath; we special-case // comparisons to null. if (!HasSameBase(LHSValue, RHSValue)) { if (E->getOpcode() == BO_Sub) { // Handle &&A - &&B. if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) return Error(E); const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr*>(); const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr*>(); if (!LHSExpr || !RHSExpr) return Error(E); const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); if (!LHSAddrExpr || !RHSAddrExpr) return Error(E); // Make sure both labels come from the same function. if (LHSAddrExpr->getLabel()->getDeclContext() != RHSAddrExpr->getLabel()->getDeclContext()) return Error(E); return Success(APValue(LHSAddrExpr, RHSAddrExpr), E); } // Inequalities and subtractions between unrelated pointers have // unspecified or undefined behavior. if (!E->isEqualityOp()) return Error(E); // A constant address may compare equal to the address of a symbol. // The one exception is that address of an object cannot compare equal // to a null pointer constant. if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || (!RHSValue.Base && !RHSValue.Offset.isZero())) return Error(E); // It's implementation-defined whether distinct literals will have // distinct addresses. In clang, the result of such a comparison is // unspecified, so it is not a constant expression. However, we do know // that the address of a literal will be non-null. if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && LHSValue.Base && RHSValue.Base) return Error(E); // We can't tell whether weak symbols will end up pointing to the same // object. if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) return Error(E); // We can't compare the address of the start of one object with the // past-the-end address of another object, per C++ DR1652. if ((LHSValue.Base && LHSValue.Offset.isZero() && isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) || (RHSValue.Base && RHSValue.Offset.isZero() && isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))) return Error(E); // We can't tell whether an object is at the same address as another // zero sized object. if ((RHSValue.Base && isZeroSized(LHSValue)) || (LHSValue.Base && isZeroSized(RHSValue))) return Error(E); // Pointers with different bases cannot represent the same object. // (Note that clang defaults to -fmerge-all-constants, which can // lead to inconsistent results for comparisons involving the address // of a constant; this generally doesn't matter in practice.) return Success(E->getOpcode() == BO_NE, E); } const CharUnits &LHSOffset = LHSValue.getLValueOffset(); const CharUnits &RHSOffset = RHSValue.getLValueOffset(); SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); if (E->getOpcode() == BO_Sub) { // C++11 [expr.add]p6: // Unless both pointers point to elements of the same array object, or // one past the last element of the array object, the behavior is // undefined. if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator, RHSDesignator)) CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); QualType Type = E->getLHS()->getType(); QualType ElementType = Type->getAs<PointerType>()->getPointeeType(); CharUnits ElementSize; if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) return false; // As an extension, a type may have zero size (empty struct or union in // C, array of zero length). Pointer subtraction in such cases has // undefined behavior, so is not constant. if (ElementSize.isZero()) { Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size) << ElementType; return false; } // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, // and produce incorrect results when it overflows. Such behavior // appears to be non-conforming, but is common, so perhaps we should // assume the standard intended for such cases to be undefined behavior // and check for them. // Compute (LHSOffset - RHSOffset) / Size carefully, checking for // overflow in the final conversion to ptrdiff_t. APSInt LHS( llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); APSInt RHS( llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); APSInt ElemSize( llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false); APSInt TrueResult = (LHS - RHS) / ElemSize; APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); if (Result.extend(65) != TrueResult && !HandleOverflow(Info, E, TrueResult, E->getType())) return false; return Success(Result, E); } // C++11 [expr.rel]p3: // Pointers to void (after pointer conversions) can be compared, with a // result defined as follows: If both pointers represent the same // address or are both the null pointer value, the result is true if the // operator is <= or >= and false otherwise; otherwise the result is // unspecified. // We interpret this as applying to pointers to *cv* void. if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && E->isRelationalOp()) CCEDiag(E, diag::note_constexpr_void_comparison); // C++11 [expr.rel]p2: // - If two pointers point to non-static data members of the same object, // or to subobjects or array elements fo such members, recursively, the // pointer to the later declared member compares greater provided the // two members have the same access control and provided their class is // not a union. // [...] // - Otherwise pointer comparisons are unspecified. if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && E->isRelationalOp()) { bool WasArrayIndex; unsigned Mismatch = FindDesignatorMismatch(getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex); // At the point where the designators diverge, the comparison has a // specified value if: // - we are comparing array indices // - we are comparing fields of a union, or fields with the same access // Otherwise, the result is unspecified and thus the comparison is not a // constant expression. if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && Mismatch < RHSDesignator.Entries.size()) { const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); if (!LF && !RF) CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); else if (!LF) CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) << getAsBaseClass(LHSDesignator.Entries[Mismatch]) << RF->getParent() << RF; else if (!RF) CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) << getAsBaseClass(RHSDesignator.Entries[Mismatch]) << LF->getParent() << LF; else if (!LF->getParent()->isUnion() && LF->getAccess() != RF->getAccess()) CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access) << LF << LF->getAccess() << RF << RF->getAccess() << LF->getParent(); } } // The comparison here must be unsigned, and performed with the same // width as the pointer. unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); uint64_t CompareLHS = LHSOffset.getQuantity(); uint64_t CompareRHS = RHSOffset.getQuantity(); assert(PtrSize <= 64 && "Unexpected pointer width"); uint64_t Mask = ~0ULL >> (64 - PtrSize); CompareLHS &= Mask; CompareRHS &= Mask; // If there is a base and this is a relational operator, we can only // compare pointers within the object in question; otherwise, the result // depends on where the object is located in memory. if (!LHSValue.Base.isNull() && E->isRelationalOp()) { QualType BaseTy = getType(LHSValue.Base); if (BaseTy->isIncompleteType()) return Error(E); CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); uint64_t OffsetLimit = Size.getQuantity(); if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) return Error(E); } switch (E->getOpcode()) { default: llvm_unreachable("missing comparison operator"); case BO_LT: return Success(CompareLHS < CompareRHS, E); case BO_GT: return Success(CompareLHS > CompareRHS, E); case BO_LE: return Success(CompareLHS <= CompareRHS, E); case BO_GE: return Success(CompareLHS >= CompareRHS, E); case BO_EQ: return Success(CompareLHS == CompareRHS, E); case BO_NE: return Success(CompareLHS != CompareRHS, E); } } } if (LHSTy->isMemberPointerType()) { assert(E->isEqualityOp() && "unexpected member pointer operation"); assert(RHSTy->isMemberPointerType() && "invalid comparison"); MemberPtr LHSValue, RHSValue; bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); if (!LHSOK && !Info.noteFailure()) return false; if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) return false; // C++11 [expr.eq]p2: // If both operands are null, they compare equal. Otherwise if only one is // null, they compare unequal. if (!LHSValue.getDecl() || !RHSValue.getDecl()) { bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); } // Otherwise if either is a pointer to a virtual member function, the // result is unspecified. if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) if (MD->isVirtual()) CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) if (MD->isVirtual()) CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; // Otherwise they compare equal if and only if they would refer to the // same member of the same most derived object or the same subobject if // they were dereferenced with a hypothetical object of the associated // class type. bool Equal = LHSValue == RHSValue; return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); } if (LHSTy->isNullPtrType()) { assert(E->isComparisonOp() && "unexpected nullptr operation"); assert(RHSTy->isNullPtrType() && "missing pointer conversion"); // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t // are compared, the result is true of the operator is <=, >= or ==, and // false otherwise. BinaryOperator::Opcode Opcode = E->getOpcode(); return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E); } assert((!LHSTy->isIntegralOrEnumerationType() || !RHSTy->isIntegralOrEnumerationType()) && "DataRecursiveIntBinOpEvaluator should have handled integral types"); // We can't continue from here for non-integral types. return ExprEvaluatorBaseTy::VisitBinaryOperator(E); } /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with /// a result as the expression's type. bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( const UnaryExprOrTypeTraitExpr *E) { switch(E->getKind()) { case UETT_AlignOf: { if (E->isArgumentType()) return Success(GetAlignOfType(Info, E->getArgumentType()), E); else return Success(GetAlignOfExpr(Info, E->getArgumentExpr()), E); } case UETT_VecStep: { QualType Ty = E->getTypeOfArgument(); if (Ty->isVectorType()) { unsigned n = Ty->castAs<VectorType>()->getNumElements(); // The vec_step built-in functions that take a 3-component // vector return 4. (OpenCL 1.1 spec 6.11.12) if (n == 3) n = 4; return Success(n, E); } else return Success(1, E); } case UETT_SizeOf: { QualType SrcTy = E->getTypeOfArgument(); // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, // the result is the size of the referenced type." if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) SrcTy = Ref->getPointeeType(); CharUnits Sizeof; if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) return false; return Success(Sizeof, E); } case UETT_OpenMPRequiredSimdAlign: assert(E->isArgumentType()); return Success( Info.Ctx.toCharUnitsFromBits( Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType())) .getQuantity(), E); } llvm_unreachable("unknown expr/type trait"); } bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { CharUnits Result; unsigned n = OOE->getNumComponents(); if (n == 0) return Error(OOE); QualType CurrentType = OOE->getTypeSourceInfo()->getType(); for (unsigned i = 0; i != n; ++i) { OffsetOfNode ON = OOE->getComponent(i); switch (ON.getKind()) { case OffsetOfNode::Array: { const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); APSInt IdxResult; if (!EvaluateInteger(Idx, IdxResult, Info)) return false; const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); if (!AT) return Error(OOE); CurrentType = AT->getElementType(); CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); Result += IdxResult.getSExtValue() * ElementSize; break; } case OffsetOfNode::Field: { FieldDecl *MemberDecl = ON.getField(); const RecordType *RT = CurrentType->getAs<RecordType>(); if (!RT) return Error(OOE); RecordDecl *RD = RT->getDecl(); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); unsigned i = MemberDecl->getFieldIndex(); assert(i < RL.getFieldCount() && "offsetof field in wrong type"); Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); CurrentType = MemberDecl->getType().getNonReferenceType(); break; } case OffsetOfNode::Identifier: llvm_unreachable("dependent __builtin_offsetof"); case OffsetOfNode::Base: { CXXBaseSpecifier *BaseSpec = ON.getBase(); if (BaseSpec->isVirtual()) return Error(OOE); // Find the layout of the class whose base we are looking into. const RecordType *RT = CurrentType->getAs<RecordType>(); if (!RT) return Error(OOE); RecordDecl *RD = RT->getDecl(); if (RD->isInvalidDecl()) return false; const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); // Find the base class itself. CurrentType = BaseSpec->getType(); const RecordType *BaseRT = CurrentType->getAs<RecordType>(); if (!BaseRT) return Error(OOE); // Add the offset to the base. Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); break; } } } return Success(Result, OOE); } bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { switch (E->getOpcode()) { default: // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. // See C99 6.6p3. return Error(E); case UO_Extension: // FIXME: Should extension allow i-c-e extension expressions in its scope? // If so, we could clear the diagnostic ID. return Visit(E->getSubExpr()); case UO_Plus: // The result is just the value. return Visit(E->getSubExpr()); case UO_Minus: { if (!Visit(E->getSubExpr())) return false; if (!Result.isInt()) return Error(E); const APSInt &Value = Result.getInt(); if (Value.isSigned() && Value.isMinSignedValue() && !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), E->getType())) return false; return Success(-Value, E); } case UO_Not: { if (!Visit(E->getSubExpr())) return false; if (!Result.isInt()) return Error(E); return Success(~Result.getInt(), E); } case UO_LNot: { bool bres; if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) return false; return Success(!bres, E); } } } /// HandleCast - This is used to evaluate implicit or explicit casts where the /// result type is integer. bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { const Expr *SubExpr = E->getSubExpr(); QualType DestType = E->getType(); QualType SrcType = SubExpr->getType(); switch (E->getCastKind()) { case CK_BaseToDerived: case CK_DerivedToBase: case CK_UncheckedDerivedToBase: case CK_Dynamic: case CK_ToUnion: case CK_ArrayToPointerDecay: case CK_FunctionToPointerDecay: case CK_NullToPointer: case CK_NullToMemberPointer: case CK_BaseToDerivedMemberPointer: case CK_DerivedToBaseMemberPointer: case CK_ReinterpretMemberPointer: case CK_ConstructorConversion: case CK_IntegralToPointer: case CK_ToVoid: case CK_VectorSplat: case CK_IntegralToFloating: case CK_FloatingCast: case CK_CPointerToObjCPointerCast: case CK_BlockPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_ObjCObjectLValueCast: case CK_FloatingRealToComplex: case CK_FloatingComplexToReal: case CK_FloatingComplexCast: case CK_FloatingComplexToIntegralComplex: case CK_IntegralRealToComplex: case CK_IntegralComplexCast: case CK_IntegralComplexToFloatingComplex: case CK_BuiltinFnToFnPtr: case CK_ZeroToOCLEvent: case CK_NonAtomicToAtomic: case CK_AddressSpaceConversion: llvm_unreachable("invalid cast kind for integral value"); case CK_BitCast: case CK_Dependent: case CK_LValueBitCast: case CK_ARCProduceObject: case CK_ARCConsumeObject: case CK_ARCReclaimReturnedObject: case CK_ARCExtendBlockObject: case CK_CopyAndAutoreleaseBlockObject: return Error(E); case CK_UserDefinedConversion: case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NoOp: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_MemberPointerToBoolean: case CK_PointerToBoolean: case CK_IntegralToBoolean: case CK_FloatingToBoolean: case CK_BooleanToSignedIntegral: case CK_FloatingComplexToBoolean: case CK_IntegralComplexToBoolean: { bool BoolResult; if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) return false; uint64_t IntResult = BoolResult; if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral) IntResult = (uint64_t)-1; return Success(IntResult, E); } case CK_IntegralCast: { if (!Visit(SubExpr)) return false; if (!Result.isInt()) { // Allow casts of address-of-label differences if they are no-ops // or narrowing. (The narrowing case isn't actually guaranteed to // be constant-evaluatable except in some narrow cases which are hard // to detect here. We let it through on the assumption the user knows // what they are doing.) if (Result.isAddrLabelDiff()) return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); // Only allow casts of lvalues if they are lossless. return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); } return Success(HandleIntToIntCast(Info, E, DestType, SrcType, Result.getInt()), E); } case CK_PointerToIntegral: { CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; LValue LV; if (!EvaluatePointer(SubExpr, LV, Info)) return false; if (LV.getLValueBase()) { // Only allow based lvalue casts if they are lossless. // FIXME: Allow a larger integer size than the pointer size, and allow // narrowing back down to pointer width in subsequent integral casts. // FIXME: Check integer type's active bits, not its type size. if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) return Error(E); LV.Designator.setInvalid(); LV.moveInto(Result); return true; } APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(), SrcType); return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); } case CK_IntegralComplexToReal: { ComplexValue C; if (!EvaluateComplex(SubExpr, C, Info)) return false; return Success(C.getComplexIntReal(), E); } case CK_FloatingToIntegral: { APFloat F(0.0); if (!EvaluateFloat(SubExpr, F, Info)) return false; APSInt Value; if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) return false; return Success(Value, E); } } llvm_unreachable("unknown cast resulting in integral value"); } bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isAnyComplexType()) { ComplexValue LV; if (!EvaluateComplex(E->getSubExpr(), LV, Info)) return false; if (!LV.isComplexInt()) return Error(E); return Success(LV.getComplexIntReal(), E); } return Visit(E->getSubExpr()); } bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isComplexIntegerType()) { ComplexValue LV; if (!EvaluateComplex(E->getSubExpr(), LV, Info)) return false; if (!LV.isComplexInt()) return Error(E); return Success(LV.getComplexIntImag(), E); } VisitIgnoredValue(E->getSubExpr()); return Success(0, E); } bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { return Success(E->getPackLength(), E); } bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { return Success(E->getValue(), E); } //===----------------------------------------------------------------------===// // Float Evaluation //===----------------------------------------------------------------------===// namespace { class FloatExprEvaluator : public ExprEvaluatorBase<FloatExprEvaluator> { APFloat &Result; public: FloatExprEvaluator(EvalInfo &info, APFloat &result) : ExprEvaluatorBaseTy(info), Result(result) {} bool Success(const APValue &V, const Expr *e) { Result = V.getFloat(); return true; } bool ZeroInitialization(const Expr *E) { Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); return true; } bool VisitCallExpr(const CallExpr *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitBinaryOperator(const BinaryOperator *E); bool VisitFloatingLiteral(const FloatingLiteral *E); bool VisitCastExpr(const CastExpr *E); bool VisitUnaryReal(const UnaryOperator *E); bool VisitUnaryImag(const UnaryOperator *E); // FIXME: Missing: array subscript of vector, member of vector }; } // end anonymous namespace static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isRealFloatingType()); return FloatExprEvaluator(Info, Result).Visit(E); } static bool TryEvaluateBuiltinNaN(const ASTContext &Context, QualType ResultTy, const Expr *Arg, bool SNaN, llvm::APFloat &Result) { const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); if (!S) return false; const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); llvm::APInt fill; // Treat empty strings as if they were zero. if (S->getString().empty()) fill = llvm::APInt(32, 0); else if (S->getString().getAsInteger(0, fill)) return false; if (Context.getTargetInfo().isNan2008()) { if (SNaN) Result = llvm::APFloat::getSNaN(Sem, false, &fill); else Result = llvm::APFloat::getQNaN(Sem, false, &fill); } else { // Prior to IEEE 754-2008, architectures were allowed to choose whether // the first bit of their significand was set for qNaN or sNaN. MIPS chose // a different encoding to what became a standard in 2008, and for pre- // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as // sNaN. This is now known as "legacy NaN" encoding. if (SNaN) Result = llvm::APFloat::getQNaN(Sem, false, &fill); else Result = llvm::APFloat::getSNaN(Sem, false, &fill); } return true; } bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { switch (E->getBuiltinCallee()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__builtin_huge_val: case Builtin::BI__builtin_huge_valf: case Builtin::BI__builtin_huge_vall: case Builtin::BI__builtin_inf: case Builtin::BI__builtin_inff: case Builtin::BI__builtin_infl: { const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); Result = llvm::APFloat::getInf(Sem); return true; } case Builtin::BI__builtin_nans: case Builtin::BI__builtin_nansf: case Builtin::BI__builtin_nansl: if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), true, Result)) return Error(E); return true; case Builtin::BI__builtin_nan: case Builtin::BI__builtin_nanf: case Builtin::BI__builtin_nanl: // If this is __builtin_nan() turn this into a nan, otherwise we // can't constant fold it. if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), false, Result)) return Error(E); return true; case Builtin::BI__builtin_fabs: case Builtin::BI__builtin_fabsf: case Builtin::BI__builtin_fabsl: if (!EvaluateFloat(E->getArg(0), Result, Info)) return false; if (Result.isNegative()) Result.changeSign(); return true; // FIXME: Builtin::BI__builtin_powi // FIXME: Builtin::BI__builtin_powif // FIXME: Builtin::BI__builtin_powil case Builtin::BI__builtin_copysign: case Builtin::BI__builtin_copysignf: case Builtin::BI__builtin_copysignl: { APFloat RHS(0.); if (!EvaluateFloat(E->getArg(0), Result, Info) || !EvaluateFloat(E->getArg(1), RHS, Info)) return false; Result.copySign(RHS); return true; } } } bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isAnyComplexType()) { ComplexValue CV; if (!EvaluateComplex(E->getSubExpr(), CV, Info)) return false; Result = CV.FloatReal; return true; } return Visit(E->getSubExpr()); } bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { if (E->getSubExpr()->getType()->isAnyComplexType()) { ComplexValue CV; if (!EvaluateComplex(E->getSubExpr(), CV, Info)) return false; Result = CV.FloatImag; return true; } VisitIgnoredValue(E->getSubExpr()); const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); Result = llvm::APFloat::getZero(Sem); return true; } bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { switch (E->getOpcode()) { default: return Error(E); case UO_Plus: return EvaluateFloat(E->getSubExpr(), Result, Info); case UO_Minus: if (!EvaluateFloat(E->getSubExpr(), Result, Info)) return false; Result.changeSign(); return true; } } bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) return ExprEvaluatorBaseTy::VisitBinaryOperator(E); APFloat RHS(0.0); bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); if (!LHSOK && !Info.noteFailure()) return false; return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); } bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { Result = E->getValue(); return true; } bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { const Expr* SubExpr = E->getSubExpr(); switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_IntegralToFloating: { APSInt IntResult; return EvaluateInteger(SubExpr, IntResult, Info) && HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, E->getType(), Result); } case CK_FloatingCast: { if (!Visit(SubExpr)) return false; return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), Result); } case CK_FloatingComplexToReal: { ComplexValue V; if (!EvaluateComplex(SubExpr, V, Info)) return false; Result = V.getComplexFloatReal(); return true; } } } //===----------------------------------------------------------------------===// // Complex Evaluation (for float and integer) //===----------------------------------------------------------------------===// namespace { class ComplexExprEvaluator : public ExprEvaluatorBase<ComplexExprEvaluator> { ComplexValue &Result; public: ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) : ExprEvaluatorBaseTy(info), Result(Result) {} bool Success(const APValue &V, const Expr *e) { Result.setFrom(V); return true; } bool ZeroInitialization(const Expr *E); //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// bool VisitImaginaryLiteral(const ImaginaryLiteral *E); bool VisitCastExpr(const CastExpr *E); bool VisitBinaryOperator(const BinaryOperator *E); bool VisitUnaryOperator(const UnaryOperator *E); bool VisitInitListExpr(const InitListExpr *E); }; } // end anonymous namespace static bool EvaluateComplex(const Expr *E, ComplexValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isAnyComplexType()); return ComplexExprEvaluator(Info, Result).Visit(E); } bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); if (ElemTy->isRealFloatingType()) { Result.makeComplexFloat(); APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); Result.FloatReal = Zero; Result.FloatImag = Zero; } else { Result.makeComplexInt(); APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); Result.IntReal = Zero; Result.IntImag = Zero; } return true; } bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { const Expr* SubExpr = E->getSubExpr(); if (SubExpr->getType()->isRealFloatingType()) { Result.makeComplexFloat(); APFloat &Imag = Result.FloatImag; if (!EvaluateFloat(SubExpr, Imag, Info)) return false; Result.FloatReal = APFloat(Imag.getSemantics()); return true; } else { assert(SubExpr->getType()->isIntegerType() && "Unexpected imaginary literal."); Result.makeComplexInt(); APSInt &Imag = Result.IntImag; if (!EvaluateInteger(SubExpr, Imag, Info)) return false; Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); return true; } } bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { case CK_BitCast: case CK_BaseToDerived: case CK_DerivedToBase: case CK_UncheckedDerivedToBase: case CK_Dynamic: case CK_ToUnion: case CK_ArrayToPointerDecay: case CK_FunctionToPointerDecay: case CK_NullToPointer: case CK_NullToMemberPointer: case CK_BaseToDerivedMemberPointer: case CK_DerivedToBaseMemberPointer: case CK_MemberPointerToBoolean: case CK_ReinterpretMemberPointer: case CK_ConstructorConversion: case CK_IntegralToPointer: case CK_PointerToIntegral: case CK_PointerToBoolean: case CK_ToVoid: case CK_VectorSplat: case CK_IntegralCast: case CK_BooleanToSignedIntegral: case CK_IntegralToBoolean: case CK_IntegralToFloating: case CK_FloatingToIntegral: case CK_FloatingToBoolean: case CK_FloatingCast: case CK_CPointerToObjCPointerCast: case CK_BlockPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_ObjCObjectLValueCast: case CK_FloatingComplexToReal: case CK_FloatingComplexToBoolean: case CK_IntegralComplexToReal: case CK_IntegralComplexToBoolean: case CK_ARCProduceObject: case CK_ARCConsumeObject: case CK_ARCReclaimReturnedObject: case CK_ARCExtendBlockObject: case CK_CopyAndAutoreleaseBlockObject: case CK_BuiltinFnToFnPtr: case CK_ZeroToOCLEvent: case CK_NonAtomicToAtomic: case CK_AddressSpaceConversion: llvm_unreachable("invalid cast kind for complex value"); case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NoOp: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_Dependent: case CK_LValueBitCast: case CK_UserDefinedConversion: return Error(E); case CK_FloatingRealToComplex: { APFloat &Real = Result.FloatReal; if (!EvaluateFloat(E->getSubExpr(), Real, Info)) return false; Result.makeComplexFloat(); Result.FloatImag = APFloat(Real.getSemantics()); return true; } case CK_FloatingComplexCast: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->getAs<ComplexType>()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); } case CK_FloatingComplexToIntegralComplex: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->getAs<ComplexType>()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); Result.makeComplexInt(); return HandleFloatToIntCast(Info, E, From, Result.FloatReal, To, Result.IntReal) && HandleFloatToIntCast(Info, E, From, Result.FloatImag, To, Result.IntImag); } case CK_IntegralRealToComplex: { APSInt &Real = Result.IntReal; if (!EvaluateInteger(E->getSubExpr(), Real, Info)) return false; Result.makeComplexInt(); Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); return true; } case CK_IntegralComplexCast: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->getAs<ComplexType>()->getElementType(); QualType From = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); return true; } case CK_IntegralComplexToFloatingComplex: { if (!Visit(E->getSubExpr())) return false; QualType To = E->getType()->castAs<ComplexType>()->getElementType(); QualType From = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); Result.makeComplexFloat(); return HandleIntToFloatCast(Info, E, From, Result.IntReal, To, Result.FloatReal) && HandleIntToFloatCast(Info, E, From, Result.IntImag, To, Result.FloatImag); } } llvm_unreachable("unknown cast resulting in complex value"); } bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) return ExprEvaluatorBaseTy::VisitBinaryOperator(E); // Track whether the LHS or RHS is real at the type system level. When this is // the case we can simplify our evaluation strategy. bool LHSReal = false, RHSReal = false; bool LHSOK; if (E->getLHS()->getType()->isRealFloatingType()) { LHSReal = true; APFloat &Real = Result.FloatReal; LHSOK = EvaluateFloat(E->getLHS(), Real, Info); if (LHSOK) { Result.makeComplexFloat(); Result.FloatImag = APFloat(Real.getSemantics()); } } else { LHSOK = Visit(E->getLHS()); } if (!LHSOK && !Info.noteFailure()) return false; ComplexValue RHS; if (E->getRHS()->getType()->isRealFloatingType()) { RHSReal = true; APFloat &Real = RHS.FloatReal; if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK) return false; RHS.makeComplexFloat(); RHS.FloatImag = APFloat(Real.getSemantics()); } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) return false; assert(!(LHSReal && RHSReal) && "Cannot have both operands of a complex operation be real."); switch (E->getOpcode()) { default: return Error(E); case BO_Add: if (Result.isComplexFloat()) { Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), APFloat::rmNearestTiesToEven); if (LHSReal) Result.getComplexFloatImag() = RHS.getComplexFloatImag(); else if (!RHSReal) Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), APFloat::rmNearestTiesToEven); } else { Result.getComplexIntReal() += RHS.getComplexIntReal(); Result.getComplexIntImag() += RHS.getComplexIntImag(); } break; case BO_Sub: if (Result.isComplexFloat()) { Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), APFloat::rmNearestTiesToEven); if (LHSReal) { Result.getComplexFloatImag() = RHS.getComplexFloatImag(); Result.getComplexFloatImag().changeSign(); } else if (!RHSReal) { Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), APFloat::rmNearestTiesToEven); } } else { Result.getComplexIntReal() -= RHS.getComplexIntReal(); Result.getComplexIntImag() -= RHS.getComplexIntImag(); } break; case BO_Mul: if (Result.isComplexFloat()) { // This is an implementation of complex multiplication according to the // constraints laid out in C11 Annex G. The implemantion uses the // following naming scheme: // (a + ib) * (c + id) ComplexValue LHS = Result; APFloat &A = LHS.getComplexFloatReal(); APFloat &B = LHS.getComplexFloatImag(); APFloat &C = RHS.getComplexFloatReal(); APFloat &D = RHS.getComplexFloatImag(); APFloat &ResR = Result.getComplexFloatReal(); APFloat &ResI = Result.getComplexFloatImag(); if (LHSReal) { assert(!RHSReal && "Cannot have two real operands for a complex op!"); ResR = A * C; ResI = A * D; } else if (RHSReal) { ResR = C * A; ResI = C * B; } else { // In the fully general case, we need to handle NaNs and infinities // robustly. APFloat AC = A * C; APFloat BD = B * D; APFloat AD = A * D; APFloat BC = B * C; ResR = AC - BD; ResI = AD + BC; if (ResR.isNaN() && ResI.isNaN()) { bool Recalc = false; if (A.isInfinity() || B.isInfinity()) { A = APFloat::copySign( APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); B = APFloat::copySign( APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); if (C.isNaN()) C = APFloat::copySign(APFloat(C.getSemantics()), C); if (D.isNaN()) D = APFloat::copySign(APFloat(D.getSemantics()), D); Recalc = true; } if (C.isInfinity() || D.isInfinity()) { C = APFloat::copySign( APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); D = APFloat::copySign( APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); if (A.isNaN()) A = APFloat::copySign(APFloat(A.getSemantics()), A); if (B.isNaN()) B = APFloat::copySign(APFloat(B.getSemantics()), B); Recalc = true; } if (!Recalc && (AC.isInfinity() || BD.isInfinity() || AD.isInfinity() || BC.isInfinity())) { if (A.isNaN()) A = APFloat::copySign(APFloat(A.getSemantics()), A); if (B.isNaN()) B = APFloat::copySign(APFloat(B.getSemantics()), B); if (C.isNaN()) C = APFloat::copySign(APFloat(C.getSemantics()), C); if (D.isNaN()) D = APFloat::copySign(APFloat(D.getSemantics()), D); Recalc = true; } if (Recalc) { ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D); ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C); } } } } else { ComplexValue LHS = Result; Result.getComplexIntReal() = (LHS.getComplexIntReal() * RHS.getComplexIntReal() - LHS.getComplexIntImag() * RHS.getComplexIntImag()); Result.getComplexIntImag() = (LHS.getComplexIntReal() * RHS.getComplexIntImag() + LHS.getComplexIntImag() * RHS.getComplexIntReal()); } break; case BO_Div: if (Result.isComplexFloat()) { // This is an implementation of complex division according to the // constraints laid out in C11 Annex G. The implemantion uses the // following naming scheme: // (a + ib) / (c + id) ComplexValue LHS = Result; APFloat &A = LHS.getComplexFloatReal(); APFloat &B = LHS.getComplexFloatImag(); APFloat &C = RHS.getComplexFloatReal(); APFloat &D = RHS.getComplexFloatImag(); APFloat &ResR = Result.getComplexFloatReal(); APFloat &ResI = Result.getComplexFloatImag(); if (RHSReal) { ResR = A / C; ResI = B / C; } else { if (LHSReal) { // No real optimizations we can do here, stub out with zero. B = APFloat::getZero(A.getSemantics()); } int DenomLogB = 0; APFloat MaxCD = maxnum(abs(C), abs(D)); if (MaxCD.isFinite()) { DenomLogB = ilogb(MaxCD); C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven); D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven); } APFloat Denom = C * C + D * D; ResR = scalbn((A * C + B * D) / Denom, -DenomLogB, APFloat::rmNearestTiesToEven); ResI = scalbn((B * C - A * D) / Denom, -DenomLogB, APFloat::rmNearestTiesToEven); if (ResR.isNaN() && ResI.isNaN()) { if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) { ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A; ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B; } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() && D.isFinite()) { A = APFloat::copySign( APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); B = APFloat::copySign( APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D); ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D); } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) { C = APFloat::copySign( APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); D = APFloat::copySign( APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D); ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D); } } } } else { if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) return Error(E, diag::note_expr_divide_by_zero); ComplexValue LHS = Result; APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + RHS.getComplexIntImag() * RHS.getComplexIntImag(); Result.getComplexIntReal() = (LHS.getComplexIntReal() * RHS.getComplexIntReal() + LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; Result.getComplexIntImag() = (LHS.getComplexIntImag() * RHS.getComplexIntReal() - LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; } break; } return true; } bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { // Get the operand value into 'Result'. if (!Visit(E->getSubExpr())) return false; switch (E->getOpcode()) { default: return Error(E); case UO_Extension: return true; case UO_Plus: // The result is always just the subexpr. return true; case UO_Minus: if (Result.isComplexFloat()) { Result.getComplexFloatReal().changeSign(); Result.getComplexFloatImag().changeSign(); } else { Result.getComplexIntReal() = -Result.getComplexIntReal(); Result.getComplexIntImag() = -Result.getComplexIntImag(); } return true; case UO_Not: if (Result.isComplexFloat()) Result.getComplexFloatImag().changeSign(); else Result.getComplexIntImag() = -Result.getComplexIntImag(); return true; } } bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { if (E->getNumInits() == 2) { if (E->getType()->isComplexType()) { Result.makeComplexFloat(); if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) return false; if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) return false; } else { Result.makeComplexInt(); if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) return false; if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) return false; } return true; } return ExprEvaluatorBaseTy::VisitInitListExpr(E); } //===----------------------------------------------------------------------===// // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic // implicit conversion. //===----------------------------------------------------------------------===// namespace { class AtomicExprEvaluator : public ExprEvaluatorBase<AtomicExprEvaluator> { APValue &Result; public: AtomicExprEvaluator(EvalInfo &Info, APValue &Result) : ExprEvaluatorBaseTy(Info), Result(Result) {} bool Success(const APValue &V, const Expr *E) { Result = V; return true; } bool ZeroInitialization(const Expr *E) { ImplicitValueInitExpr VIE( E->getType()->castAs<AtomicType>()->getValueType()); return Evaluate(Result, Info, &VIE); } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_NonAtomicToAtomic: return Evaluate(Result, Info, E->getSubExpr()); } } }; } // end anonymous namespace static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isAtomicType()); return AtomicExprEvaluator(Info, Result).Visit(E); } //===----------------------------------------------------------------------===// // Void expression evaluation, primarily for a cast to void on the LHS of a // comma operator //===----------------------------------------------------------------------===// namespace { class VoidExprEvaluator : public ExprEvaluatorBase<VoidExprEvaluator> { public: VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} bool Success(const APValue &V, const Expr *e) { return true; } bool VisitCastExpr(const CastExpr *E) { switch (E->getCastKind()) { default: return ExprEvaluatorBaseTy::VisitCastExpr(E); case CK_ToVoid: VisitIgnoredValue(E->getSubExpr()); return true; } } bool VisitCallExpr(const CallExpr *E) { switch (E->getBuiltinCallee()) { default: return ExprEvaluatorBaseTy::VisitCallExpr(E); case Builtin::BI__assume: case Builtin::BI__builtin_assume: // The argument is not evaluated! return true; } } }; } // end anonymous namespace static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { assert(E->isRValue() && E->getType()->isVoidType()); return VoidExprEvaluator(Info).Visit(E); } //===----------------------------------------------------------------------===// // Top level Expr::EvaluateAsRValue method. //===----------------------------------------------------------------------===// static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { // In C, function designators are not lvalues, but we evaluate them as if they // are. QualType T = E->getType(); if (E->isGLValue() || T->isFunctionType()) { LValue LV; if (!EvaluateLValue(E, LV, Info)) return false; LV.moveInto(Result); } else if (T->isVectorType()) { if (!EvaluateVector(E, Result, Info)) return false; } else if (T->isIntegralOrEnumerationType()) { if (!IntExprEvaluator(Info, Result).Visit(E)) return false; } else if (T->hasPointerRepresentation()) { LValue LV; if (!EvaluatePointer(E, LV, Info)) return false; LV.moveInto(Result); } else if (T->isRealFloatingType()) { llvm::APFloat F(0.0); if (!EvaluateFloat(E, F, Info)) return false; Result = APValue(F); } else if (T->isAnyComplexType()) { ComplexValue C; if (!EvaluateComplex(E, C, Info)) return false; C.moveInto(Result); } else if (T->isMemberPointerType()) { MemberPtr P; if (!EvaluateMemberPointer(E, P, Info)) return false; P.moveInto(Result); return true; } else if (T->isArrayType()) { LValue LV; LV.set(E, Info.CurrentCall->Index); APValue &Value = Info.CurrentCall->createTemporary(E, false); if (!EvaluateArray(E, LV, Value, Info)) return false; Result = Value; } else if (T->isRecordType()) { LValue LV; LV.set(E, Info.CurrentCall->Index); APValue &Value = Info.CurrentCall->createTemporary(E, false); if (!EvaluateRecord(E, LV, Value, Info)) return false; Result = Value; } else if (T->isVoidType()) { if (!Info.getLangOpts().CPlusPlus11) Info.CCEDiag(E, diag::note_constexpr_nonliteral) << E->getType(); if (!EvaluateVoid(E, Info)) return false; } else if (T->isAtomicType()) { if (!EvaluateAtomic(E, Result, Info)) return false; } else if (Info.getLangOpts().CPlusPlus11) { Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType(); return false; } else { Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); return false; } return true; } /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some /// cases, the in-place evaluation is essential, since later initializers for /// an object can indirectly refer to subobjects which were initialized earlier. static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, const Expr *E, bool AllowNonLiteralTypes) { assert(!E->isValueDependent()); if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) return false; if (E->isRValue()) { // Evaluate arrays and record types in-place, so that later initializers can // refer to earlier-initialized members of the object. if (E->getType()->isArrayType()) return EvaluateArray(E, This, Result, Info); else if (E->getType()->isRecordType()) return EvaluateRecord(E, This, Result, Info); } // For any other type, in-place evaluation is unimportant. return Evaluate(Result, Info, E); } /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit /// lvalue-to-rvalue cast if it is an lvalue. static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { if (E->getType().isNull()) return false; if (!CheckLiteralType(Info, E)) return false; if (!::Evaluate(Result, Info, E)) return false; if (E->isGLValue()) { LValue LV; LV.setFrom(Info.Ctx, Result); if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) return false; } // Check this core constant expression is a constant expression. return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); } static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, const ASTContext &Ctx, bool &IsConst) { // Fast-path evaluations of integer literals, since we sometimes see files // containing vast quantities of these. if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) { Result.Val = APValue(APSInt(L->getValue(), L->getType()->isUnsignedIntegerType())); IsConst = true; return true; } // This case should be rare, but we need to check it before we check on // the type below. if (Exp->getType().isNull()) { IsConst = false; return true; } // FIXME: Evaluating values of large array and record types can cause // performance problems. Only do so in C++11 for now. if (Exp->isRValue() && (Exp->getType()->isArrayType() || Exp->getType()->isRecordType()) && !Ctx.getLangOpts().CPlusPlus11) { IsConst = false; return true; } return false; } /// EvaluateAsRValue - Return true if this is a constant which we can fold using /// any crazy technique (that has nothing to do with language standards) that /// we want to. If this function returns true, it returns the folded constant /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion /// will be applied to the result. bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const { bool IsConst; if (FastEvaluateAsRValue(this, Result, Ctx, IsConst)) return IsConst; EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); return ::EvaluateAsRValue(Info, this, Result.Val); } bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx) const { EvalResult Scratch; return EvaluateAsRValue(Scratch, Ctx) && HandleConversionToBool(Scratch.Val, Result); } static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result, Expr::SideEffectsKind SEK) { return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) || (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior); } bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx, SideEffectsKind AllowSideEffects) const { if (!getType()->isIntegralOrEnumerationType()) return false; EvalResult ExprResult; if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() || hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) return false; Result = ExprResult.Val.getInt(); return true; } bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx, SideEffectsKind AllowSideEffects) const { if (!getType()->isRealFloatingType()) return false; EvalResult ExprResult; if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isFloat() || hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) return false; Result = ExprResult.Val.getFloat(); return true; } bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const { EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); LValue LV; if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || !CheckLValueConstantExpression(Info, getExprLoc(), Ctx.getLValueReferenceType(getType()), LV)) return false; LV.moveInto(Result.Val); return true; } bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, const VarDecl *VD, SmallVectorImpl<PartialDiagnosticAt> &Notes) const { // FIXME: Evaluating initializers for large array and record types can cause // performance problems. Only do so in C++11 for now. if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && !Ctx.getLangOpts().CPlusPlus11) return false; Expr::EvalStatus EStatus; EStatus.Diag = &Notes; EvalInfo InitInfo(Ctx, EStatus, VD->isConstexpr() ? EvalInfo::EM_ConstantExpression : EvalInfo::EM_ConstantFold); InitInfo.setEvaluatingDecl(VD, Value); LValue LVal; LVal.set(VD); // C++11 [basic.start.init]p2: // Variables with static storage duration or thread storage duration shall be // zero-initialized before any other initialization takes place. // This behavior is not present in C. if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && !VD->getType()->isReferenceType()) { ImplicitValueInitExpr VIE(VD->getType()); if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, /*AllowNonLiteralTypes=*/true)) return false; } if (!EvaluateInPlace(Value, InitInfo, LVal, this, /*AllowNonLiteralTypes=*/true) || EStatus.HasSideEffects) return false; return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), Value); } /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be /// constant folded, but discard the result. bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const { EvalResult Result; return EvaluateAsRValue(Result, Ctx) && !hasUnacceptableSideEffect(Result, SEK); } APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const { EvalResult EvalResult; EvalResult.Diag = Diag; bool Result = EvaluateAsRValue(EvalResult, Ctx); (void)Result; assert(Result && "Could not evaluate expression"); assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer"); return EvalResult.Val.getInt(); } void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { bool IsConst; EvalResult EvalResult; if (!FastEvaluateAsRValue(this, EvalResult, Ctx, IsConst)) { EvalInfo Info(Ctx, EvalResult, EvalInfo::EM_EvaluateForOverflow); (void)::EvaluateAsRValue(Info, this, EvalResult.Val); } } bool Expr::EvalResult::isGlobalLValue() const { assert(Val.isLValue()); return IsGlobalLValue(Val.getLValueBase()); } /// isIntegerConstantExpr - this recursive routine will test if an expression is /// an integer constant expression. /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, /// comma, etc // CheckICE - This function does the fundamental ICE checking: the returned // ICEDiag contains an ICEKind indicating whether the expression is an ICE, // and a (possibly null) SourceLocation indicating the location of the problem. // // Note that to reduce code duplication, this helper does no evaluation // itself; the caller checks whether the expression is evaluatable, and // in the rare cases where CheckICE actually cares about the evaluated // value, it calls into Evalute. namespace { enum ICEKind { /// This expression is an ICE. IK_ICE, /// This expression is not an ICE, but if it isn't evaluated, it's /// a legal subexpression for an ICE. This return value is used to handle /// the comma operator in C99 mode, and non-constant subexpressions. IK_ICEIfUnevaluated, /// This expression is not an ICE, and is not a legal subexpression for one. IK_NotICE }; struct ICEDiag { ICEKind Kind; SourceLocation Loc; ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} }; } static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { Expr::EvalResult EVResult; if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects || !EVResult.Val.isInt()) return ICEDiag(IK_NotICE, E->getLocStart()); return NoDiag(); } static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { assert(!E->isValueDependent() && "Should not see value dependent exprs!"); if (!E->getType()->isIntegralOrEnumerationType()) return ICEDiag(IK_NotICE, E->getLocStart()); switch (E->getStmtClass()) { #define ABSTRACT_STMT(Node) #define STMT(Node, Base) case Expr::Node##Class: #define EXPR(Node, Base) #include "clang/AST/StmtNodes.inc" case Expr::PredefinedExprClass: case Expr::FloatingLiteralClass: case Expr::ImaginaryLiteralClass: case Expr::StringLiteralClass: case Expr::ArraySubscriptExprClass: case Expr::OMPArraySectionExprClass: case Expr::MemberExprClass: case Expr::CompoundAssignOperatorClass: case Expr::CompoundLiteralExprClass: case Expr::ExtVectorElementExprClass: case Expr::DesignatedInitExprClass: case Expr::NoInitExprClass: case Expr::DesignatedInitUpdateExprClass: case Expr::ImplicitValueInitExprClass: case Expr::ParenListExprClass: case Expr::VAArgExprClass: case Expr::AddrLabelExprClass: case Expr::StmtExprClass: case Expr::CXXMemberCallExprClass: case Expr::CUDAKernelCallExprClass: case Expr::CXXDynamicCastExprClass: case Expr::CXXTypeidExprClass: case Expr::CXXUuidofExprClass: case Expr::MSPropertyRefExprClass: case Expr::MSPropertySubscriptExprClass: case Expr::CXXNullPtrLiteralExprClass: case Expr::UserDefinedLiteralClass: case Expr::CXXThisExprClass: case Expr::CXXThrowExprClass: case Expr::CXXNewExprClass: case Expr::CXXDeleteExprClass: case Expr::CXXPseudoDestructorExprClass: case Expr::UnresolvedLookupExprClass: case Expr::TypoExprClass: case Expr::DependentScopeDeclRefExprClass: case Expr::CXXConstructExprClass: case Expr::CXXInheritedCtorInitExprClass: case Expr::CXXStdInitializerListExprClass: case Expr::CXXBindTemporaryExprClass: case Expr::ExprWithCleanupsClass: case Expr::CXXTemporaryObjectExprClass: case Expr::CXXUnresolvedConstructExprClass: case Expr::CXXDependentScopeMemberExprClass: case Expr::UnresolvedMemberExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCBoxedExprClass: case Expr::ObjCArrayLiteralClass: case Expr::ObjCDictionaryLiteralClass: case Expr::ObjCEncodeExprClass: case Expr::ObjCMessageExprClass: case Expr::ObjCSelectorExprClass: case Expr::ObjCProtocolExprClass: case Expr::ObjCIvarRefExprClass: case Expr::ObjCPropertyRefExprClass: case Expr::ObjCSubscriptRefExprClass: case Expr::ObjCIsaExprClass: case Expr::ShuffleVectorExprClass: case Expr::ConvertVectorExprClass: case Expr::BlockExprClass: case Expr::NoStmtClass: case Expr::OpaqueValueExprClass: case Expr::PackExpansionExprClass: case Expr::SubstNonTypeTemplateParmPackExprClass: case Expr::FunctionParmPackExprClass: case Expr::AsTypeExprClass: case Expr::ObjCIndirectCopyRestoreExprClass: case Expr::MaterializeTemporaryExprClass: case Expr::PseudoObjectExprClass: case Expr::AtomicExprClass: case Expr::LambdaExprClass: case Expr::CXXFoldExprClass: case Expr::CoawaitExprClass: case Expr::CoyieldExprClass: return ICEDiag(IK_NotICE, E->getLocStart()); case Expr::InitListExprClass: { // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the // form "T x = { a };" is equivalent to "T x = a;". // Unless we're initializing a reference, T is a scalar as it is known to be // of integral or enumeration type. if (E->isRValue()) if (cast<InitListExpr>(E)->getNumInits() == 1) return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx); return ICEDiag(IK_NotICE, E->getLocStart()); } case Expr::SizeOfPackExprClass: case Expr::GNUNullExprClass: // GCC considers the GNU __null value to be an integral constant expression. return NoDiag(); case Expr::SubstNonTypeTemplateParmExprClass: return CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); case Expr::ParenExprClass: return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); case Expr::GenericSelectionExprClass: return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); case Expr::IntegerLiteralClass: case Expr::CharacterLiteralClass: case Expr::ObjCBoolLiteralExprClass: case Expr::CXXBoolLiteralExprClass: case Expr::CXXScalarValueInitExprClass: case Expr::TypeTraitExprClass: case Expr::ArrayTypeTraitExprClass: case Expr::ExpressionTraitExprClass: case Expr::CXXNoexceptExprClass: return NoDiag(); case Expr::CallExprClass: case Expr::CXXOperatorCallExprClass: { // C99 6.6/3 allows function calls within unevaluated subexpressions of // constant expressions, but they can never be ICEs because an ICE cannot // contain an operand of (pointer to) function type. const CallExpr *CE = cast<CallExpr>(E); if (CE->getBuiltinCallee()) return CheckEvalInICE(E, Ctx); return ICEDiag(IK_NotICE, E->getLocStart()); } case Expr::DeclRefExprClass: { if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl())) return NoDiag(); const ValueDecl *D = dyn_cast<ValueDecl>(cast<DeclRefExpr>(E)->getDecl()); if (Ctx.getLangOpts().CPlusPlus && D && IsConstNonVolatile(D->getType())) { // Parameter variables are never constants. Without this check, // getAnyInitializer() can find a default argument, which leads // to chaos. if (isa<ParmVarDecl>(D)) return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); // C++ 7.1.5.1p2 // A variable of non-volatile const-qualified integral or enumeration // type initialized by an ICE can be used in ICEs. if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) { if (!Dcl->getType()->isIntegralOrEnumerationType()) return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); const VarDecl *VD; // Look for a declaration of this variable that has an initializer, and // check whether it is an ICE. if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) return NoDiag(); else return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); } } return ICEDiag(IK_NotICE, E->getLocStart()); } case Expr::UnaryOperatorClass: { const UnaryOperator *Exp = cast<UnaryOperator>(E); switch (Exp->getOpcode()) { case UO_PostInc: case UO_PostDec: case UO_PreInc: case UO_PreDec: case UO_AddrOf: case UO_Deref: case UO_Coawait: // C99 6.6/3 allows increment and decrement within unevaluated // subexpressions of constant expressions, but they can never be ICEs // because an ICE cannot contain an lvalue operand. return ICEDiag(IK_NotICE, E->getLocStart()); case UO_Extension: case UO_LNot: case UO_Plus: case UO_Minus: case UO_Not: case UO_Real: case UO_Imag: return CheckICE(Exp->getSubExpr(), Ctx); } // OffsetOf falls through here. } case Expr::OffsetOfExprClass: { // Note that per C99, offsetof must be an ICE. And AFAIK, using // EvaluateAsRValue matches the proposed gcc behavior for cases like // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect // compliance: we should warn earlier for offsetof expressions with // array subscripts that aren't ICEs, and if the array subscripts // are ICEs, the value of the offsetof must be an integer constant. return CheckEvalInICE(E, Ctx); } case Expr::UnaryExprOrTypeTraitExprClass: { const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); if ((Exp->getKind() == UETT_SizeOf) && Exp->getTypeOfArgument()->isVariableArrayType()) return ICEDiag(IK_NotICE, E->getLocStart()); return NoDiag(); } case Expr::BinaryOperatorClass: { const BinaryOperator *Exp = cast<BinaryOperator>(E); switch (Exp->getOpcode()) { case BO_PtrMemD: case BO_PtrMemI: case BO_Assign: case BO_MulAssign: case BO_DivAssign: case BO_RemAssign: case BO_AddAssign: case BO_SubAssign: case BO_ShlAssign: case BO_ShrAssign: case BO_AndAssign: case BO_XorAssign: case BO_OrAssign: // C99 6.6/3 allows assignments within unevaluated subexpressions of // constant expressions, but they can never be ICEs because an ICE cannot // contain an lvalue operand. return ICEDiag(IK_NotICE, E->getLocStart()); case BO_Mul: case BO_Div: case BO_Rem: case BO_Add: case BO_Sub: case BO_Shl: case BO_Shr: case BO_LT: case BO_GT: case BO_LE: case BO_GE: case BO_EQ: case BO_NE: case BO_And: case BO_Xor: case BO_Or: case BO_Comma: { ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); if (Exp->getOpcode() == BO_Div || Exp->getOpcode() == BO_Rem) { // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure // we don't evaluate one. if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); if (REval == 0) return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); if (REval.isSigned() && REval.isAllOnesValue()) { llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); if (LEval.isMinSignedValue()) return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); } } } if (Exp->getOpcode() == BO_Comma) { if (Ctx.getLangOpts().C99) { // C99 6.6p3 introduces a strange edge case: comma can be in an ICE // if it isn't evaluated. if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); } else { // In both C89 and C++, commas in ICEs are illegal. return ICEDiag(IK_NotICE, E->getLocStart()); } } return Worst(LHSResult, RHSResult); } case BO_LAnd: case BO_LOr: { ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { // Rare case where the RHS has a comma "side-effect"; we need // to actually check the condition to see whether the side // with the comma is evaluated. if ((Exp->getOpcode() == BO_LAnd) != (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) return RHSResult; return NoDiag(); } return Worst(LHSResult, RHSResult); } } } case Expr::ImplicitCastExprClass: case Expr::CStyleCastExprClass: case Expr::CXXFunctionalCastExprClass: case Expr::CXXStaticCastExprClass: case Expr::CXXReinterpretCastExprClass: case Expr::CXXConstCastExprClass: case Expr::ObjCBridgedCastExprClass: { const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); if (isa<ExplicitCastExpr>(E)) { if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { unsigned DestWidth = Ctx.getIntWidth(E->getType()); bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); APSInt IgnoredVal(DestWidth, !DestSigned); bool Ignored; // If the value does not fit in the destination type, the behavior is // undefined, so we are not required to treat it as a constant // expression. if (FL->getValue().convertToInteger(IgnoredVal, llvm::APFloat::rmTowardZero, &Ignored) & APFloat::opInvalidOp) return ICEDiag(IK_NotICE, E->getLocStart()); return NoDiag(); } } switch (cast<CastExpr>(E)->getCastKind()) { case CK_LValueToRValue: case CK_AtomicToNonAtomic: case CK_NonAtomicToAtomic: case CK_NoOp: case CK_IntegralToBoolean: case CK_IntegralCast: return CheckICE(SubExpr, Ctx); default: return ICEDiag(IK_NotICE, E->getLocStart()); } } case Expr::BinaryConditionalOperatorClass: { const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); if (CommonResult.Kind == IK_NotICE) return CommonResult; ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); if (FalseResult.Kind == IK_NotICE) return FalseResult; if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; if (FalseResult.Kind == IK_ICEIfUnevaluated && Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); return FalseResult; } case Expr::ConditionalOperatorClass: { const ConditionalOperator *Exp = cast<ConditionalOperator>(E); // If the condition (ignoring parens) is a __builtin_constant_p call, // then only the true side is actually considered in an integer constant // expression, and it is fully evaluated. This is an important GNU // extension. See GCC PR38377 for discussion. if (const CallExpr *CallCE = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) return CheckEvalInICE(E, Ctx); ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); if (CondResult.Kind == IK_NotICE) return CondResult; ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); if (TrueResult.Kind == IK_NotICE) return TrueResult; if (FalseResult.Kind == IK_NotICE) return FalseResult; if (CondResult.Kind == IK_ICEIfUnevaluated) return CondResult; if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) return NoDiag(); // Rare case where the diagnostics depend on which side is evaluated // Note that if we get here, CondResult is 0, and at least one of // TrueResult and FalseResult is non-zero. if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) return FalseResult; return TrueResult; } case Expr::CXXDefaultArgExprClass: return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); case Expr::CXXDefaultInitExprClass: return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx); case Expr::ChooseExprClass: { return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx); } } llvm_unreachable("Invalid StmtClass!"); } /// Evaluate an expression as a C++11 integral constant expression. static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, const Expr *E, llvm::APSInt *Value, SourceLocation *Loc) { if (!E->getType()->isIntegralOrEnumerationType()) { if (Loc) *Loc = E->getExprLoc(); return false; } APValue Result; if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) return false; if (!Result.isInt()) { if (Loc) *Loc = E->getExprLoc(); return false; } if (Value) *Value = Result.getInt(); return true; } bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, SourceLocation *Loc) const { if (Ctx.getLangOpts().CPlusPlus11) return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc); ICEDiag D = CheckICE(this, Ctx); if (D.Kind != IK_ICE) { if (Loc) *Loc = D.Loc; return false; } return true; } bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx, SourceLocation *Loc, bool isEvaluated) const { if (Ctx.getLangOpts().CPlusPlus11) return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); if (!isIntegerConstantExpr(Ctx, Loc)) return false; // The only possible side-effects here are due to UB discovered in the // evaluation (for instance, INT_MAX + 1). In such a case, we are still // required to treat the expression as an ICE, so we produce the folded // value. if (!EvaluateAsInt(Value, Ctx, SE_AllowSideEffects)) llvm_unreachable("ICE cannot be evaluated!"); return true; } bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { return CheckICE(this, Ctx).Kind == IK_ICE; } bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, SourceLocation *Loc) const { // We support this checking in C++98 mode in order to diagnose compatibility // issues. assert(Ctx.getLangOpts().CPlusPlus); // Build evaluation settings. Expr::EvalStatus Status; SmallVector<PartialDiagnosticAt, 8> Diags; Status.Diag = &Diags; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); APValue Scratch; bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); if (!Diags.empty()) { IsConstExpr = false; if (Loc) *Loc = Diags[0].first; } else if (!IsConstExpr) { // FIXME: This shouldn't happen. if (Loc) *Loc = getExprLoc(); } return IsConstExpr; } bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx, const FunctionDecl *Callee, ArrayRef<const Expr*> Args) const { Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated); ArgVector ArgValues(Args.size()); for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); I != E; ++I) { if ((*I)->isValueDependent() || !Evaluate(ArgValues[I - Args.begin()], Info, *I)) // If evaluation fails, throw away the argument entirely. ArgValues[I - Args.begin()] = APValue(); if (Info.EvalStatus.HasSideEffects) return false; } // Build fake call to Callee. CallStackFrame Frame(Info, Callee->getLocation(), Callee, /*This*/nullptr, ArgValues.data()); return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects; } bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, SmallVectorImpl< PartialDiagnosticAt> &Diags) { // FIXME: It would be useful to check constexpr function templates, but at the // moment the constant expression evaluator cannot cope with the non-rigorous // ASTs which we build for dependent expressions. if (FD->isDependentContext()) return true; Expr::EvalStatus Status; Status.Diag = &Diags; EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_PotentialConstantExpression); const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr; // Fabricate an arbitrary expression on the stack and pretend that it // is a temporary being used as the 'this' pointer. LValue This; ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); This.set(&VIE, Info.CurrentCall->Index); ArrayRef<const Expr*> Args; APValue Scratch; if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { // Evaluate the call as a constant initializer, to allow the construction // of objects of non-literal types. Info.setEvaluatingDecl(This.getLValueBase(), Scratch); HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch); } else { SourceLocation Loc = FD->getLocation(); HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr, Args, FD->getBody(), Info, Scratch, nullptr); } return Diags.empty(); } bool Expr::isPotentialConstantExprUnevaluated(Expr *E, const FunctionDecl *FD, SmallVectorImpl< PartialDiagnosticAt> &Diags) { Expr::EvalStatus Status; Status.Diag = &Diags; EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_PotentialConstantExpressionUnevaluated); // Fabricate a call stack frame to give the arguments a plausible cover story. ArrayRef<const Expr*> Args; ArgVector ArgValues(0); bool Success = EvaluateArgs(Args, ArgValues, Info); (void)Success; assert(Success && "Failed to set up arguments for potential constant evaluation"); CallStackFrame Frame(Info, SourceLocation(), FD, nullptr, ArgValues.data()); APValue ResultScratch; Evaluate(ResultScratch, Info, E); return Diags.empty(); } bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx, unsigned Type) const { if (!getType()->isPointerType()) return false; Expr::EvalStatus Status; EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); return ::tryEvaluateBuiltinObjectSize(this, Type, Info, Result); }