//===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides an abstract class for C++ code generation. Concrete subclasses
// of this implement code generation for specific C++ ABIs.
//
//===----------------------------------------------------------------------===//
#ifndef CLANG_CODEGEN_CXXABI_H
#define CLANG_CODEGEN_CXXABI_H
#include "clang/Basic/LLVM.h"
#include "CodeGenFunction.h"
namespace llvm {
class Constant;
class Type;
class Value;
}
namespace clang {
class CastExpr;
class CXXConstructorDecl;
class CXXDestructorDecl;
class CXXMethodDecl;
class CXXRecordDecl;
class FieldDecl;
class MangleContext;
namespace CodeGen {
class CodeGenFunction;
class CodeGenModule;
/// Implements C++ ABI-specific code generation functions.
class CGCXXABI {
protected:
CodeGenModule &CGM;
OwningPtr<MangleContext> MangleCtx;
CGCXXABI(CodeGenModule &CGM)
: CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
protected:
ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) {
return CGF.CXXABIThisDecl;
}
llvm::Value *&getThisValue(CodeGenFunction &CGF) {
return CGF.CXXABIThisValue;
}
ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) {
return CGF.CXXVTTDecl;
}
llvm::Value *&getVTTValue(CodeGenFunction &CGF) {
return CGF.CXXVTTValue;
}
/// Build a parameter variable suitable for 'this'.
void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
/// Perform prolog initialization of the parameter variable suitable
/// for 'this' emitted by BuildThisParam.
void EmitThisParam(CodeGenFunction &CGF);
ASTContext &getContext() const { return CGM.getContext(); }
public:
virtual ~CGCXXABI();
/// Gets the mangle context.
MangleContext &getMangleContext() {
return *MangleCtx;
}
/// Find the LLVM type used to represent the given member pointer
/// type.
virtual llvm::Type *
ConvertMemberPointerType(const MemberPointerType *MPT);
/// Load a member function from an object and a member function
/// pointer. Apply the this-adjustment and set 'This' to the
/// adjusted value.
virtual llvm::Value *
EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
llvm::Value *&This,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
/// Calculate an l-value from an object and a data member pointer.
virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF,
llvm::Value *Base,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
/// Perform a derived-to-base, base-to-derived, or bitcast member
/// pointer conversion.
virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src);
/// Perform a derived-to-base, base-to-derived, or bitcast member
/// pointer conversion on a constant value.
virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src);
/// Return true if the given member pointer can be zero-initialized
/// (in the C++ sense) with an LLVM zeroinitializer.
virtual bool isZeroInitializable(const MemberPointerType *MPT);
/// Create a null member pointer of the given type.
virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
/// Create a member pointer for the given method.
virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
/// Create a member pointer for the given field.
virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset);
/// Create a member pointer for the given member pointer constant.
virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
/// Emit a comparison between two member pointers. Returns an i1.
virtual llvm::Value *
EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L,
llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality);
/// Determine if a member pointer is non-null. Returns an i1.
virtual llvm::Value *
EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
protected:
/// A utility method for computing the offset required for the given
/// base-to-derived or derived-to-base member-pointer conversion.
/// Does not handle virtual conversions (in case we ever fully
/// support an ABI that allows this). Returns null if no adjustment
/// is required.
llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);
public:
/// Build the signature of the given constructor variant by adding
/// any required parameters. For convenience, ResTy has been
/// initialized to 'void', and ArgTys has been initialized with the
/// type of 'this' (although this may be changed by the ABI) and
/// will have the formal parameters added to it afterwards.
///
/// If there are ever any ABIs where the implicit parameters are
/// intermixed with the formal parameters, we can address those
/// then.
virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
CXXCtorType T,
CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys) = 0;
/// Build the signature of the given destructor variant by adding
/// any required parameters. For convenience, ResTy has been
/// initialized to 'void' and ArgTys has been initialized with the
/// type of 'this' (although this may be changed by the ABI).
virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
CXXDtorType T,
CanQualType &ResTy,
SmallVectorImpl<CanQualType> &ArgTys) = 0;
/// Build the ABI-specific portion of the parameter list for a
/// function. This generally involves a 'this' parameter and
/// possibly some extra data for constructors and destructors.
///
/// ABIs may also choose to override the return type, which has been
/// initialized with the formal return type of the function.
virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF,
QualType &ResTy,
FunctionArgList &Params) = 0;
/// Emit the ABI-specific prolog for the function.
virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
RValue RV, QualType ResultType);
/**************************** Array cookies ******************************/
/// Returns the extra size required in order to store the array
/// cookie for the given type. May return 0 to indicate that no
/// array cookie is required.
///
/// Several cases are filtered out before this method is called:
/// - non-array allocations never need a cookie
/// - calls to ::operator new(size_t, void*) never need a cookie
///
/// \param ElementType - the allocated type of the expression,
/// i.e. the pointee type of the expression result type
virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
/// Initialize the array cookie for the given allocation.
///
/// \param NewPtr - a char* which is the presumed-non-null
/// return value of the allocation function
/// \param NumElements - the computed number of elements,
/// potentially collapsed from the multidimensional array case
/// \param ElementType - the base element allocated type,
/// i.e. the allocated type after stripping all array types
virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType);
/// Reads the array cookie associated with the given pointer,
/// if it has one.
///
/// \param Ptr - a pointer to the first element in the array
/// \param ElementType - the base element type of elements of the array
/// \param NumElements - an out parameter which will be initialized
/// with the number of elements allocated, or zero if there is no
/// cookie
/// \param AllocPtr - an out parameter which will be initialized
/// with a char* pointing to the address returned by the allocation
/// function
/// \param CookieSize - an out parameter which will be initialized
/// with the size of the cookie, or zero if there is no cookie
virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
const CXXDeleteExpr *expr,
QualType ElementType, llvm::Value *&NumElements,
llvm::Value *&AllocPtr, CharUnits &CookieSize);
/*************************** Static local guards ****************************/
/// Emits the guarded initializer and destructor setup for the given
/// variable, given that it couldn't be emitted as a constant.
/// If \p PerformInit is false, the initialization has been folded to a
/// constant and should not be performed.
///
/// The variable may be:
/// - a static local variable
/// - a static data member of a class template instantiation
virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::GlobalVariable *DeclPtr, bool PerformInit);
};
/// Creates an instance of a C++ ABI class.
CGCXXABI *CreateARMCXXABI(CodeGenModule &CGM);
CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);
}
}
#endif