// SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- C++ -*-
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines SimpleSValBuilder, a basic implementation of SValBuilder.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
using namespace clang;
using namespace ento;
namespace {
class SimpleSValBuilder : public SValBuilder {
protected:
virtual SVal dispatchCast(SVal val, QualType castTy);
virtual SVal evalCastFromNonLoc(NonLoc val, QualType castTy);
virtual SVal evalCastFromLoc(Loc val, QualType castTy);
public:
SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
ProgramStateManager &stateMgr)
: SValBuilder(alloc, context, stateMgr) {}
virtual ~SimpleSValBuilder() {}
virtual SVal evalMinus(NonLoc val);
virtual SVal evalComplement(NonLoc val);
virtual SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
NonLoc lhs, NonLoc rhs, QualType resultTy);
virtual SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
Loc lhs, Loc rhs, QualType resultTy);
virtual SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
Loc lhs, NonLoc rhs, QualType resultTy);
/// getKnownValue - evaluates a given SVal. If the SVal has only one possible
/// (integer) value, that value is returned. Otherwise, returns NULL.
virtual const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V);
SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op,
const llvm::APSInt &RHS, QualType resultTy);
};
} // end anonymous namespace
SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
ASTContext &context,
ProgramStateManager &stateMgr) {
return new SimpleSValBuilder(alloc, context, stateMgr);
}
//===----------------------------------------------------------------------===//
// Transfer function for Casts.
//===----------------------------------------------------------------------===//
SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) {
assert(isa<Loc>(&Val) || isa<NonLoc>(&Val));
return isa<Loc>(Val) ? evalCastFromLoc(cast<Loc>(Val), CastTy)
: evalCastFromNonLoc(cast<NonLoc>(Val), CastTy);
}
SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) {
bool isLocType = Loc::isLocType(castTy);
if (nonloc::LocAsInteger *LI = dyn_cast<nonloc::LocAsInteger>(&val)) {
if (isLocType)
return LI->getLoc();
// FIXME: Correctly support promotions/truncations.
unsigned castSize = Context.getTypeSize(castTy);
if (castSize == LI->getNumBits())
return val;
return makeLocAsInteger(LI->getLoc(), castSize);
}
if (const SymExpr *se = val.getAsSymbolicExpression()) {
QualType T = Context.getCanonicalType(se->getType(Context));
// If types are the same or both are integers, ignore the cast.
// FIXME: Remove this hack when we support symbolic truncation/extension.
// HACK: If both castTy and T are integers, ignore the cast. This is
// not a permanent solution. Eventually we want to precisely handle
// extension/truncation of symbolic integers. This prevents us from losing
// precision when we assign 'x = y' and 'y' is symbolic and x and y are
// different integer types.
if (haveSameType(T, castTy))
return val;
if (!isLocType)
return makeNonLoc(se, T, castTy);
return UnknownVal();
}
// If value is a non integer constant, produce unknown.
if (!isa<nonloc::ConcreteInt>(val))
return UnknownVal();
// Only handle casts from integers to integers - if val is an integer constant
// being cast to a non integer type, produce unknown.
if (!isLocType && !castTy->isIntegerType())
return UnknownVal();
llvm::APSInt i = cast<nonloc::ConcreteInt>(val).getValue();
i.setIsUnsigned(castTy->isUnsignedIntegerOrEnumerationType() ||
Loc::isLocType(castTy));
i = i.extOrTrunc(Context.getTypeSize(castTy));
if (isLocType)
return makeIntLocVal(i);
else
return makeIntVal(i);
}
SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) {
// Casts from pointers -> pointers, just return the lval.
//
// Casts from pointers -> references, just return the lval. These
// can be introduced by the frontend for corner cases, e.g
// casting from va_list* to __builtin_va_list&.
//
if (Loc::isLocType(castTy) || castTy->isReferenceType())
return val;
// FIXME: Handle transparent unions where a value can be "transparently"
// lifted into a union type.
if (castTy->isUnionType())
return UnknownVal();
if (castTy->isIntegerType()) {
unsigned BitWidth = Context.getTypeSize(castTy);
if (!isa<loc::ConcreteInt>(val))
return makeLocAsInteger(val, BitWidth);
llvm::APSInt i = cast<loc::ConcreteInt>(val).getValue();
i.setIsUnsigned(castTy->isUnsignedIntegerOrEnumerationType() ||
Loc::isLocType(castTy));
i = i.extOrTrunc(BitWidth);
return makeIntVal(i);
}
// All other cases: return 'UnknownVal'. This includes casting pointers
// to floats, which is probably badness it itself, but this is a good
// intermediate solution until we do something better.
return UnknownVal();
}
//===----------------------------------------------------------------------===//
// Transfer function for unary operators.
//===----------------------------------------------------------------------===//
SVal SimpleSValBuilder::evalMinus(NonLoc val) {
switch (val.getSubKind()) {
case nonloc::ConcreteIntKind:
return cast<nonloc::ConcreteInt>(val).evalMinus(*this);
default:
return UnknownVal();
}
}
SVal SimpleSValBuilder::evalComplement(NonLoc X) {
switch (X.getSubKind()) {
case nonloc::ConcreteIntKind:
return cast<nonloc::ConcreteInt>(X).evalComplement(*this);
default:
return UnknownVal();
}
}
//===----------------------------------------------------------------------===//
// Transfer function for binary operators.
//===----------------------------------------------------------------------===//
static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) {
switch (op) {
default:
llvm_unreachable("Invalid opcode.");
case BO_LT: return BO_GE;
case BO_GT: return BO_LE;
case BO_LE: return BO_GT;
case BO_GE: return BO_LT;
case BO_EQ: return BO_NE;
case BO_NE: return BO_EQ;
}
}
static BinaryOperator::Opcode ReverseComparison(BinaryOperator::Opcode op) {
switch (op) {
default:
llvm_unreachable("Invalid opcode.");
case BO_LT: return BO_GT;
case BO_GT: return BO_LT;
case BO_LE: return BO_GE;
case BO_GE: return BO_LE;
case BO_EQ:
case BO_NE:
return op;
}
}
SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS,
BinaryOperator::Opcode op,
const llvm::APSInt &RHS,
QualType resultTy) {
bool isIdempotent = false;
// Check for a few special cases with known reductions first.
switch (op) {
default:
// We can't reduce this case; just treat it normally.
break;
case BO_Mul:
// a*0 and a*1
if (RHS == 0)
return makeIntVal(0, resultTy);
else if (RHS == 1)
isIdempotent = true;
break;
case BO_Div:
// a/0 and a/1
if (RHS == 0)
// This is also handled elsewhere.
return UndefinedVal();
else if (RHS == 1)
isIdempotent = true;
break;
case BO_Rem:
// a%0 and a%1
if (RHS == 0)
// This is also handled elsewhere.
return UndefinedVal();
else if (RHS == 1)
return makeIntVal(0, resultTy);
break;
case BO_Add:
case BO_Sub:
case BO_Shl:
case BO_Shr:
case BO_Xor:
// a+0, a-0, a<<0, a>>0, a^0
if (RHS == 0)
isIdempotent = true;
break;
case BO_And:
// a&0 and a&(~0)
if (RHS == 0)
return makeIntVal(0, resultTy);
else if (RHS.isAllOnesValue())
isIdempotent = true;
break;
case BO_Or:
// a|0 and a|(~0)
if (RHS == 0)
isIdempotent = true;
else if (RHS.isAllOnesValue()) {
const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS);
return nonloc::ConcreteInt(Result);
}
break;
}
// Idempotent ops (like a*1) can still change the type of an expression.
// Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the
// dirty work.
if (isIdempotent)
return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy);
// If we reach this point, the expression cannot be simplified.
// Make a SymbolVal for the entire expression.
return makeNonLoc(LHS, op, RHS, resultTy);
}
SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state,
BinaryOperator::Opcode op,
NonLoc lhs, NonLoc rhs,
QualType resultTy) {
// Handle trivial case where left-side and right-side are the same.
if (lhs == rhs)
switch (op) {
default:
break;
case BO_EQ:
case BO_LE:
case BO_GE:
return makeTruthVal(true, resultTy);
case BO_LT:
case BO_GT:
case BO_NE:
return makeTruthVal(false, resultTy);
case BO_Xor:
case BO_Sub:
return makeIntVal(0, resultTy);
case BO_Or:
case BO_And:
return evalCastFromNonLoc(lhs, resultTy);
}
while (1) {
switch (lhs.getSubKind()) {
default:
return makeGenericVal(state, op, lhs, rhs, resultTy);
case nonloc::LocAsIntegerKind: {
Loc lhsL = cast<nonloc::LocAsInteger>(lhs).getLoc();
switch (rhs.getSubKind()) {
case nonloc::LocAsIntegerKind:
return evalBinOpLL(state, op, lhsL,
cast<nonloc::LocAsInteger>(rhs).getLoc(),
resultTy);
case nonloc::ConcreteIntKind: {
// Transform the integer into a location and compare.
llvm::APSInt i = cast<nonloc::ConcreteInt>(rhs).getValue();
i.setIsUnsigned(true);
i = i.extOrTrunc(Context.getTypeSize(Context.VoidPtrTy));
return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy);
}
default:
switch (op) {
case BO_EQ:
return makeTruthVal(false, resultTy);
case BO_NE:
return makeTruthVal(true, resultTy);
default:
// This case also handles pointer arithmetic.
return makeGenericVal(state, op, lhs, rhs, resultTy);
}
}
}
case nonloc::ConcreteIntKind: {
const nonloc::ConcreteInt& lhsInt = cast<nonloc::ConcreteInt>(lhs);
// Is the RHS a symbol we can simplify?
// FIXME: This was mostly copy/pasted from the LHS-is-a-symbol case.
if (const nonloc::SymbolVal *srhs = dyn_cast<nonloc::SymbolVal>(&rhs)) {
SymbolRef RSym = srhs->getSymbol();
if (RSym->getType(Context)->isIntegerType()) {
if (const llvm::APSInt *Constant = state->getSymVal(RSym)) {
// The symbol evaluates to a constant.
const llvm::APSInt *rhs_I;
if (BinaryOperator::isRelationalOp(op))
rhs_I = &BasicVals.Convert(lhsInt.getValue(), *Constant);
else
rhs_I = &BasicVals.Convert(resultTy, *Constant);
rhs = nonloc::ConcreteInt(*rhs_I);
}
}
}
if (isa<nonloc::ConcreteInt>(rhs)) {
return lhsInt.evalBinOp(*this, op, cast<nonloc::ConcreteInt>(rhs));
} else {
const llvm::APSInt& lhsValue = lhsInt.getValue();
// Swap the left and right sides and flip the operator if doing so
// allows us to better reason about the expression (this is a form
// of expression canonicalization).
// While we're at it, catch some special cases for non-commutative ops.
NonLoc tmp = rhs;
rhs = lhs;
lhs = tmp;
switch (op) {
case BO_LT:
case BO_GT:
case BO_LE:
case BO_GE:
op = ReverseComparison(op);
continue;
case BO_EQ:
case BO_NE:
case BO_Add:
case BO_Mul:
case BO_And:
case BO_Xor:
case BO_Or:
continue;
case BO_Shr:
if (lhsValue.isAllOnesValue() && lhsValue.isSigned())
// At this point lhs and rhs have been swapped.
return rhs;
// FALL-THROUGH
case BO_Shl:
if (lhsValue == 0)
// At this point lhs and rhs have been swapped.
return rhs;
return makeGenericVal(state, op, rhs, lhs, resultTy);
default:
return makeGenericVal(state, op, rhs, lhs, resultTy);
}
}
}
case nonloc::SymbolValKind: {
nonloc::SymbolVal *selhs = cast<nonloc::SymbolVal>(&lhs);
// LHS is a symbolic expression.
if (selhs->isExpression()) {
// Only handle LHS of the form "$sym op constant", at least for now.
const SymIntExpr *symIntExpr =
dyn_cast<SymIntExpr>(selhs->getSymbol());
if (!symIntExpr)
return makeGenericVal(state, op, lhs, rhs, resultTy);
// Is this a logical not? (!x is represented as x == 0.)
if (op == BO_EQ && rhs.isZeroConstant()) {
// We know how to negate certain expressions. Simplify them here.
BinaryOperator::Opcode opc = symIntExpr->getOpcode();
switch (opc) {
default:
// We don't know how to negate this operation.
// Just handle it as if it were a normal comparison to 0.
break;
case BO_LAnd:
case BO_LOr:
llvm_unreachable("Logical operators handled by branching logic.");
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:
case BO_Comma:
llvm_unreachable("'=' and ',' operators handled by ExprEngine.");
case BO_PtrMemD:
case BO_PtrMemI:
llvm_unreachable("Pointer arithmetic not handled here.");
case BO_LT:
case BO_GT:
case BO_LE:
case BO_GE:
case BO_EQ:
case BO_NE:
// Negate the comparison and make a value.
opc = NegateComparison(opc);
assert(symIntExpr->getType(Context) == resultTy);
return makeNonLoc(symIntExpr->getLHS(), opc,
symIntExpr->getRHS(), resultTy);
}
}
// For now, only handle expressions whose RHS is a constant.
const nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs);
if (!rhsInt)
return makeGenericVal(state, op, lhs, rhs, resultTy);
// If both the LHS and the current expression are additive,
// fold their constants.
if (BinaryOperator::isAdditiveOp(op)) {
BinaryOperator::Opcode lop = symIntExpr->getOpcode();
if (BinaryOperator::isAdditiveOp(lop)) {
// resultTy may not be the best type to convert to, but it's
// probably the best choice in expressions with mixed type
// (such as x+1U+2LL). The rules for implicit conversions should
// choose a reasonable type to preserve the expression, and will
// at least match how the value is going to be used.
const llvm::APSInt &first =
BasicVals.Convert(resultTy, symIntExpr->getRHS());
const llvm::APSInt &second =
BasicVals.Convert(resultTy, rhsInt->getValue());
const llvm::APSInt *newRHS;
if (lop == op)
newRHS = BasicVals.evalAPSInt(BO_Add, first, second);
else
newRHS = BasicVals.evalAPSInt(BO_Sub, first, second);
return MakeSymIntVal(symIntExpr->getLHS(), lop, *newRHS, resultTy);
}
}
// Otherwise, make a SymbolVal out of the expression.
return MakeSymIntVal(symIntExpr, op, rhsInt->getValue(), resultTy);
// LHS is a simple symbol (not a symbolic expression).
} else {
nonloc::SymbolVal *slhs = cast<nonloc::SymbolVal>(&lhs);
SymbolRef Sym = slhs->getSymbol();
QualType lhsType = Sym->getType(Context);
// The conversion type is usually the result type, but not in the case
// of relational expressions.
QualType conversionType = resultTy;
if (BinaryOperator::isRelationalOp(op))
conversionType = lhsType;
// Does the symbol simplify to a constant? If so, "fold" the constant
// by setting 'lhs' to a ConcreteInt and try again.
if (lhsType->isIntegerType())
if (const llvm::APSInt *Constant = state->getSymVal(Sym)) {
// The symbol evaluates to a constant. If necessary, promote the
// folded constant (LHS) to the result type.
const llvm::APSInt &lhs_I = BasicVals.Convert(conversionType,
*Constant);
lhs = nonloc::ConcreteInt(lhs_I);
// Also promote the RHS (if necessary).
// For shifts, it is not necessary to promote the RHS.
if (BinaryOperator::isShiftOp(op))
continue;
// Other operators: do an implicit conversion. This shouldn't be
// necessary once we support truncation/extension of symbolic values.
if (nonloc::ConcreteInt *rhs_I = dyn_cast<nonloc::ConcreteInt>(&rhs)){
rhs = nonloc::ConcreteInt(BasicVals.Convert(conversionType,
rhs_I->getValue()));
}
continue;
}
// Is the RHS a symbol we can simplify?
if (const nonloc::SymbolVal *srhs = dyn_cast<nonloc::SymbolVal>(&rhs)) {
SymbolRef RSym = srhs->getSymbol();
if (RSym->getType(Context)->isIntegerType()) {
if (const llvm::APSInt *Constant = state->getSymVal(RSym)) {
// The symbol evaluates to a constant.
const llvm::APSInt &rhs_I = BasicVals.Convert(conversionType,
*Constant);
rhs = nonloc::ConcreteInt(rhs_I);
}
}
}
if (isa<nonloc::ConcreteInt>(rhs)) {
return MakeSymIntVal(slhs->getSymbol(), op,
cast<nonloc::ConcreteInt>(rhs).getValue(),
resultTy);
}
return makeGenericVal(state, op, lhs, rhs, resultTy);
}
}
}
}
}
// FIXME: all this logic will change if/when we have MemRegion::getLocation().
SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state,
BinaryOperator::Opcode op,
Loc lhs, Loc rhs,
QualType resultTy) {
// Only comparisons and subtractions are valid operations on two pointers.
// See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15].
// However, if a pointer is casted to an integer, evalBinOpNN may end up
// calling this function with another operation (PR7527). We don't attempt to
// model this for now, but it could be useful, particularly when the
// "location" is actually an integer value that's been passed through a void*.
if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub))
return UnknownVal();
// Special cases for when both sides are identical.
if (lhs == rhs) {
switch (op) {
default:
llvm_unreachable("Unimplemented operation for two identical values");
case BO_Sub:
return makeZeroVal(resultTy);
case BO_EQ:
case BO_LE:
case BO_GE:
return makeTruthVal(true, resultTy);
case BO_NE:
case BO_LT:
case BO_GT:
return makeTruthVal(false, resultTy);
}
}
switch (lhs.getSubKind()) {
default:
llvm_unreachable("Ordering not implemented for this Loc.");
case loc::GotoLabelKind:
// The only thing we know about labels is that they're non-null.
if (rhs.isZeroConstant()) {
switch (op) {
default:
break;
case BO_Sub:
return evalCastFromLoc(lhs, resultTy);
case BO_EQ:
case BO_LE:
case BO_LT:
return makeTruthVal(false, resultTy);
case BO_NE:
case BO_GT:
case BO_GE:
return makeTruthVal(true, resultTy);
}
}
// There may be two labels for the same location, and a function region may
// have the same address as a label at the start of the function (depending
// on the ABI).
// FIXME: we can probably do a comparison against other MemRegions, though.
// FIXME: is there a way to tell if two labels refer to the same location?
return UnknownVal();
case loc::ConcreteIntKind: {
// If one of the operands is a symbol and the other is a constant,
// build an expression for use by the constraint manager.
if (SymbolRef rSym = rhs.getAsLocSymbol()) {
// We can only build expressions with symbols on the left,
// so we need a reversible operator.
if (!BinaryOperator::isComparisonOp(op))
return UnknownVal();
const llvm::APSInt &lVal = cast<loc::ConcreteInt>(lhs).getValue();
return makeNonLoc(rSym, ReverseComparison(op), lVal, resultTy);
}
// If both operands are constants, just perform the operation.
if (loc::ConcreteInt *rInt = dyn_cast<loc::ConcreteInt>(&rhs)) {
SVal ResultVal = cast<loc::ConcreteInt>(lhs).evalBinOp(BasicVals, op,
*rInt);
if (Loc *Result = dyn_cast<Loc>(&ResultVal))
return evalCastFromLoc(*Result, resultTy);
else
return UnknownVal();
}
// Special case comparisons against NULL.
// This must come after the test if the RHS is a symbol, which is used to
// build constraints. The address of any non-symbolic region is guaranteed
// to be non-NULL, as is any label.
assert(isa<loc::MemRegionVal>(rhs) || isa<loc::GotoLabel>(rhs));
if (lhs.isZeroConstant()) {
switch (op) {
default:
break;
case BO_EQ:
case BO_GT:
case BO_GE:
return makeTruthVal(false, resultTy);
case BO_NE:
case BO_LT:
case BO_LE:
return makeTruthVal(true, resultTy);
}
}
// Comparing an arbitrary integer to a region or label address is
// completely unknowable.
return UnknownVal();
}
case loc::MemRegionKind: {
if (loc::ConcreteInt *rInt = dyn_cast<loc::ConcreteInt>(&rhs)) {
// If one of the operands is a symbol and the other is a constant,
// build an expression for use by the constraint manager.
if (SymbolRef lSym = lhs.getAsLocSymbol())
return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy);
// Special case comparisons to NULL.
// This must come after the test if the LHS is a symbol, which is used to
// build constraints. The address of any non-symbolic region is guaranteed
// to be non-NULL.
if (rInt->isZeroConstant()) {
switch (op) {
default:
break;
case BO_Sub:
return evalCastFromLoc(lhs, resultTy);
case BO_EQ:
case BO_LT:
case BO_LE:
return makeTruthVal(false, resultTy);
case BO_NE:
case BO_GT:
case BO_GE:
return makeTruthVal(true, resultTy);
}
}
// Comparing a region to an arbitrary integer is completely unknowable.
return UnknownVal();
}
// Get both values as regions, if possible.
const MemRegion *LeftMR = lhs.getAsRegion();
assert(LeftMR && "MemRegionKind SVal doesn't have a region!");
const MemRegion *RightMR = rhs.getAsRegion();
if (!RightMR)
// The RHS is probably a label, which in theory could address a region.
// FIXME: we can probably make a more useful statement about non-code
// regions, though.
return UnknownVal();
// If both values wrap regions, see if they're from different base regions.
const MemRegion *LeftBase = LeftMR->getBaseRegion();
const MemRegion *RightBase = RightMR->getBaseRegion();
if (LeftBase != RightBase &&
!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) {
switch (op) {
default:
return UnknownVal();
case BO_EQ:
return makeTruthVal(false, resultTy);
case BO_NE:
return makeTruthVal(true, resultTy);
}
}
// The two regions are from the same base region. See if they're both a
// type of region we know how to compare.
const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace();
const MemSpaceRegion *RightMS = RightBase->getMemorySpace();
// Heuristic: assume that no symbolic region (whose memory space is
// unknown) is on the stack.
// FIXME: we should be able to be more precise once we can do better
// aliasing constraints for symbolic regions, but this is a reasonable,
// albeit unsound, assumption that holds most of the time.
if (isa<StackSpaceRegion>(LeftMS) ^ isa<StackSpaceRegion>(RightMS)) {
switch (op) {
default:
break;
case BO_EQ:
return makeTruthVal(false, resultTy);
case BO_NE:
return makeTruthVal(true, resultTy);
}
}
// FIXME: If/when there is a getAsRawOffset() for FieldRegions, this
// ElementRegion path and the FieldRegion path below should be unified.
if (const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR)) {
// First see if the right region is also an ElementRegion.
const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR);
if (!RightER)
return UnknownVal();
// Next, see if the two ERs have the same super-region and matching types.
// FIXME: This should do something useful even if the types don't match,
// though if both indexes are constant the RegionRawOffset path will
// give the correct answer.
if (LeftER->getSuperRegion() == RightER->getSuperRegion() &&
LeftER->getElementType() == RightER->getElementType()) {
// Get the left index and cast it to the correct type.
// If the index is unknown or undefined, bail out here.
SVal LeftIndexVal = LeftER->getIndex();
NonLoc *LeftIndex = dyn_cast<NonLoc>(&LeftIndexVal);
if (!LeftIndex)
return UnknownVal();
LeftIndexVal = evalCastFromNonLoc(*LeftIndex, resultTy);
LeftIndex = dyn_cast<NonLoc>(&LeftIndexVal);
if (!LeftIndex)
return UnknownVal();
// Do the same for the right index.
SVal RightIndexVal = RightER->getIndex();
NonLoc *RightIndex = dyn_cast<NonLoc>(&RightIndexVal);
if (!RightIndex)
return UnknownVal();
RightIndexVal = evalCastFromNonLoc(*RightIndex, resultTy);
RightIndex = dyn_cast<NonLoc>(&RightIndexVal);
if (!RightIndex)
return UnknownVal();
// Actually perform the operation.
// evalBinOpNN expects the two indexes to already be the right type.
return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy);
}
// If the element indexes aren't comparable, see if the raw offsets are.
RegionRawOffset LeftOffset = LeftER->getAsArrayOffset();
RegionRawOffset RightOffset = RightER->getAsArrayOffset();
if (LeftOffset.getRegion() != NULL &&
LeftOffset.getRegion() == RightOffset.getRegion()) {
CharUnits left = LeftOffset.getOffset();
CharUnits right = RightOffset.getOffset();
switch (op) {
default:
return UnknownVal();
case BO_LT:
return makeTruthVal(left < right, resultTy);
case BO_GT:
return makeTruthVal(left > right, resultTy);
case BO_LE:
return makeTruthVal(left <= right, resultTy);
case BO_GE:
return makeTruthVal(left >= right, resultTy);
case BO_EQ:
return makeTruthVal(left == right, resultTy);
case BO_NE:
return makeTruthVal(left != right, resultTy);
}
}
// If we get here, we have no way of comparing the ElementRegions.
return UnknownVal();
}
// See if both regions are fields of the same structure.
// FIXME: This doesn't handle nesting, inheritance, or Objective-C ivars.
if (const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR)) {
// Only comparisons are meaningful here!
if (!BinaryOperator::isComparisonOp(op))
return UnknownVal();
// First see if the right region is also a FieldRegion.
const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR);
if (!RightFR)
return UnknownVal();
// Next, see if the two FRs have the same super-region.
// FIXME: This doesn't handle casts yet, and simply stripping the casts
// doesn't help.
if (LeftFR->getSuperRegion() != RightFR->getSuperRegion())
return UnknownVal();
const FieldDecl *LeftFD = LeftFR->getDecl();
const FieldDecl *RightFD = RightFR->getDecl();
const RecordDecl *RD = LeftFD->getParent();
// Make sure the two FRs are from the same kind of record. Just in case!
// FIXME: This is probably where inheritance would be a problem.
if (RD != RightFD->getParent())
return UnknownVal();
// We know for sure that the two fields are not the same, since that
// would have given us the same SVal.
if (op == BO_EQ)
return makeTruthVal(false, resultTy);
if (op == BO_NE)
return makeTruthVal(true, resultTy);
// Iterate through the fields and see which one comes first.
// [C99 6.7.2.1.13] "Within a structure object, the non-bit-field
// members and the units in which bit-fields reside have addresses that
// increase in the order in which they are declared."
bool leftFirst = (op == BO_LT || op == BO_LE);
for (RecordDecl::field_iterator I = RD->field_begin(),
E = RD->field_end(); I!=E; ++I) {
if (*I == LeftFD)
return makeTruthVal(leftFirst, resultTy);
if (*I == RightFD)
return makeTruthVal(!leftFirst, resultTy);
}
llvm_unreachable("Fields not found in parent record's definition");
}
// If we get here, we have no way of comparing the regions.
return UnknownVal();
}
}
}
SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state,
BinaryOperator::Opcode op,
Loc lhs, NonLoc rhs, QualType resultTy) {
// Special case: rhs is a zero constant.
if (rhs.isZeroConstant())
return lhs;
// Special case: 'rhs' is an integer that has the same width as a pointer and
// we are using the integer location in a comparison. Normally this cannot be
// triggered, but transfer functions like those for OSCommpareAndSwapBarrier32
// can generate comparisons that trigger this code.
// FIXME: Are all locations guaranteed to have pointer width?
if (BinaryOperator::isComparisonOp(op)) {
if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
const llvm::APSInt *x = &rhsInt->getValue();
ASTContext &ctx = Context;
if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) {
// Convert the signedness of the integer (if necessary).
if (x->isSigned())
x = &getBasicValueFactory().getValue(*x, true);
return evalBinOpLL(state, op, lhs, loc::ConcreteInt(*x), resultTy);
}
}
}
// We are dealing with pointer arithmetic.
// Handle pointer arithmetic on constant values.
if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
if (loc::ConcreteInt *lhsInt = dyn_cast<loc::ConcreteInt>(&lhs)) {
const llvm::APSInt &leftI = lhsInt->getValue();
assert(leftI.isUnsigned());
llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true);
// Convert the bitwidth of rightI. This should deal with overflow
// since we are dealing with concrete values.
rightI = rightI.extOrTrunc(leftI.getBitWidth());
// Offset the increment by the pointer size.
llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true);
rightI *= Multiplicand;
// Compute the adjusted pointer.
switch (op) {
case BO_Add:
rightI = leftI + rightI;
break;
case BO_Sub:
rightI = leftI - rightI;
break;
default:
llvm_unreachable("Invalid pointer arithmetic operation");
}
return loc::ConcreteInt(getBasicValueFactory().getValue(rightI));
}
}
// Handle cases where 'lhs' is a region.
if (const MemRegion *region = lhs.getAsRegion()) {
rhs = cast<NonLoc>(convertToArrayIndex(rhs));
SVal index = UnknownVal();
const MemRegion *superR = 0;
QualType elementType;
if (const ElementRegion *elemReg = dyn_cast<ElementRegion>(region)) {
assert(op == BO_Add || op == BO_Sub);
index = evalBinOpNN(state, op, elemReg->getIndex(), rhs,
getArrayIndexType());
superR = elemReg->getSuperRegion();
elementType = elemReg->getElementType();
}
else if (isa<SubRegion>(region)) {
superR = region;
index = rhs;
if (const PointerType *PT = resultTy->getAs<PointerType>()) {
elementType = PT->getPointeeType();
}
else {
const ObjCObjectPointerType *OT =
resultTy->getAs<ObjCObjectPointerType>();
elementType = OT->getPointeeType();
}
}
if (NonLoc *indexV = dyn_cast<NonLoc>(&index)) {
return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV,
superR, getContext()));
}
}
return UnknownVal();
}
const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state,
SVal V) {
if (V.isUnknownOrUndef())
return NULL;
if (loc::ConcreteInt* X = dyn_cast<loc::ConcreteInt>(&V))
return &X->getValue();
if (nonloc::ConcreteInt* X = dyn_cast<nonloc::ConcreteInt>(&V))
return &X->getValue();
if (SymbolRef Sym = V.getAsSymbol())
return state->getSymVal(Sym);
// FIXME: Add support for SymExprs.
return NULL;
}