lib/CodeGen/CGCXXABI.cpp - platform/external/clang - Git at Google

 //===----- CGCXXABI.cpp - 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.
 //
 //===----------------------------------------------------------------------===//

 #include "CGCXXABI.h"

 using namespace clang;
 using namespace CodeGen;

 CGCXXABI::~CGCXXABI() { }

 static void ErrorUnsupportedABI(CodeGenFunction &CGF,
                                 StringRef S) {
   DiagnosticsEngine &Diags = CGF.CGM.getDiags();
   unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
                                           "cannot yet compile %0 in this ABI");
   Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()),
                DiagID)
     << S;
 }

 static llvm::Constant *GetBogusMemberPointer(CodeGenModule &CGM,
                                              QualType T) {
   return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
 }

 llvm::Type *
 CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
   return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
 }

 llvm::Value *CGCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
                                                        llvm::Value *&This,
                                                        llvm::Value *MemPtr,
                                                  const MemberPointerType *MPT) {
   ErrorUnsupportedABI(CGF, "calls through member pointers");

   const FunctionProtoType *FPT =
     MPT->getPointeeType()->getAs<FunctionProtoType>();
   const CXXRecordDecl *RD =
     cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
   llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
                               CGM.getTypes().arrangeCXXMethodType(RD, FPT));
   return llvm::Constant::getNullValue(FTy->getPointerTo());
 }

 llvm::Value *CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
                                                     llvm::Value *Base,
                                                     llvm::Value *MemPtr,
                                               const MemberPointerType *MPT) {
   ErrorUnsupportedABI(CGF, "loads of member pointers");
   llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())->getPointerTo();
   return llvm::Constant::getNullValue(Ty);
 }

 llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
                                                    const CastExpr *E,
                                                    llvm::Value *Src) {
   ErrorUnsupportedABI(CGF, "member function pointer conversions");
   return GetBogusMemberPointer(CGM, E->getType());
 }

 llvm::Constant *CGCXXABI::EmitMemberPointerConversion(const CastExpr *E,
                                                       llvm::Constant *Src) {
   return GetBogusMemberPointer(CGM, E->getType());
 }

 llvm::Value *
 CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
                                       llvm::Value *L,
                                       llvm::Value *R,
                                       const MemberPointerType *MPT,
                                       bool Inequality) {
   ErrorUnsupportedABI(CGF, "member function pointer comparison");
   return CGF.Builder.getFalse();
 }

 llvm::Value *
 CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
                                      llvm::Value *MemPtr,
                                      const MemberPointerType *MPT) {
   ErrorUnsupportedABI(CGF, "member function pointer null testing");
   return CGF.Builder.getFalse();
 }

 llvm::Constant *
 CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
   return GetBogusMemberPointer(CGM, QualType(MPT, 0));
 }

 llvm::Constant *CGCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) {
   return GetBogusMemberPointer(CGM,
                          CGM.getContext().getMemberPointerType(MD->getType(),
                                          MD->getParent()->getTypeForDecl()));
 }

 llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
                                                 CharUnits offset) {
   return GetBogusMemberPointer(CGM, QualType(MPT, 0));
 }

 llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) {
   return GetBogusMemberPointer(CGM, MPT);
 }

 bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
   // Fake answer.
   return true;
 }

 void CGCXXABI::BuildThisParam(CodeGenFunction &CGF, FunctionArgList &params) {
   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());

   // FIXME: I'm not entirely sure I like using a fake decl just for code
   // generation. Maybe we can come up with a better way?
   ImplicitParamDecl *ThisDecl
     = ImplicitParamDecl::Create(CGM.getContext(), 0, MD->getLocation(),
                                 &CGM.getContext().Idents.get("this"),
                                 MD->getThisType(CGM.getContext()));
   params.push_back(ThisDecl);
   getThisDecl(CGF) = ThisDecl;
 }

 void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
   /// Initialize the 'this' slot.
   assert(getThisDecl(CGF) && "no 'this' variable for function");
   getThisValue(CGF)
     = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
                              "this");
 }

 void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
                                    RValue RV, QualType ResultType) {
   CGF.EmitReturnOfRValue(RV, ResultType);
 }

 CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
   if (!requiresArrayCookie(expr))
     return CharUnits::Zero();
   return getArrayCookieSizeImpl(expr->getAllocatedType());
 }

 CharUnits CGCXXABI::getArrayCookieSizeImpl(QualType elementType) {
   // BOGUS
   return CharUnits::Zero();
 }

 llvm::Value *CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
                                              llvm::Value *NewPtr,
                                              llvm::Value *NumElements,
                                              const CXXNewExpr *expr,
                                              QualType ElementType) {
   // Should never be called.
   ErrorUnsupportedABI(CGF, "array cookie initialization");
   return 0;
 }

 bool CGCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
                                    QualType elementType) {
   // If the class's usual deallocation function takes two arguments,
   // it needs a cookie.
   if (expr->doesUsualArrayDeleteWantSize())
     return true;

   return elementType.isDestructedType();
 }

 bool CGCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
   // If the class's usual deallocation function takes two arguments,
   // it needs a cookie.
   if (expr->doesUsualArrayDeleteWantSize())
     return true;

   return expr->getAllocatedType().isDestructedType();
 }

 void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *ptr,
                                const CXXDeleteExpr *expr, QualType eltTy,
                                llvm::Value *&numElements,
                                llvm::Value *&allocPtr, CharUnits &cookieSize) {
   // Derive a char* in the same address space as the pointer.
   unsigned AS = ptr->getType()->getPointerAddressSpace();
   llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS);
   ptr = CGF.Builder.CreateBitCast(ptr, charPtrTy);

   // If we don't need an array cookie, bail out early.
   if (!requiresArrayCookie(expr, eltTy)) {
     allocPtr = ptr;
     numElements = 0;
     cookieSize = CharUnits::Zero();
     return;
   }

   cookieSize = getArrayCookieSizeImpl(eltTy);
   allocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(ptr,
                                                     -cookieSize.getQuantity());
   numElements = readArrayCookieImpl(CGF, allocPtr, cookieSize);
 }

 llvm::Value *CGCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
                                            llvm::Value *ptr,
                                            CharUnits cookieSize) {
   ErrorUnsupportedABI(CGF, "reading a new[] cookie");
   return llvm::ConstantInt::get(CGF.SizeTy, 0);
 }

 void CGCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
                                const VarDecl &D,
                                llvm::GlobalVariable *GV,
                                bool PerformInit) {
   ErrorUnsupportedABI(CGF, "static local variable initialization");
 }

 void CGCXXABI::registerGlobalDtor(CodeGenFunction &CGF,
                                   llvm::Constant *dtor,
                                   llvm::Constant *addr) {
   // The default behavior is to use atexit.
   CGF.registerGlobalDtorWithAtExit(dtor, addr);
 }

 /// Returns the adjustment, in bytes, required for the given
 /// member-pointer operation.  Returns null if no adjustment is
 /// required.
 llvm::Constant *CGCXXABI::getMemberPointerAdjustment(const CastExpr *E) {
   assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
          E->getCastKind() == CK_BaseToDerivedMemberPointer);

   QualType derivedType;
   if (E->getCastKind() == CK_DerivedToBaseMemberPointer)
     derivedType = E->getSubExpr()->getType();
   else
     derivedType = E->getType();

   const CXXRecordDecl *derivedClass =
     derivedType->castAs<MemberPointerType>()->getClass()->getAsCXXRecordDecl();

   return CGM.GetNonVirtualBaseClassOffset(derivedClass,
                                           E->path_begin(),
                                           E->path_end());
 }

 llvm::BasicBlock *CGCXXABI::EmitCtorCompleteObjectHandler(
                                                          CodeGenFunction &CGF) {
   if (CGM.getTarget().getCXXABI().hasConstructorVariants())
     llvm_unreachable("shouldn't be called in this ABI");

   ErrorUnsupportedABI(CGF, "complete object detection in ctor");
   return 0;
 }
	//===----- CGCXXABI.cpp - 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.
	//
	//===----------------------------------------------------------------------===//

	#include "CGCXXABI.h"

	using namespace clang;
	using namespace CodeGen;

	CGCXXABI::~CGCXXABI() { }

	static void ErrorUnsupportedABI(CodeGenFunction &CGF,
	StringRef S) {
	DiagnosticsEngine &Diags = CGF.CGM.getDiags();
	unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
	"cannot yet compile %0 in this ABI");
	Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()),
	DiagID)
	<< S;
	}

	static llvm::Constant *GetBogusMemberPointer(CodeGenModule &CGM,
	QualType T) {
	return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
	}

	llvm::Type *
	CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
	return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
	}

	llvm::Value *CGCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
	llvm::Value *&This,
	llvm::Value *MemPtr,
	const MemberPointerType *MPT) {
	ErrorUnsupportedABI(CGF, "calls through member pointers");

	const FunctionProtoType *FPT =
	MPT->getPointeeType()->getAs<FunctionProtoType>();
	const CXXRecordDecl *RD =
	cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
	llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
	CGM.getTypes().arrangeCXXMethodType(RD, FPT));
	return llvm::Constant::getNullValue(FTy->getPointerTo());
	}

	llvm::Value *CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
	llvm::Value *Base,
	llvm::Value *MemPtr,
	const MemberPointerType *MPT) {
	ErrorUnsupportedABI(CGF, "loads of member pointers");
	llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())->getPointerTo();
	return llvm::Constant::getNullValue(Ty);
	}

	llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
	const CastExpr *E,
	llvm::Value *Src) {
	ErrorUnsupportedABI(CGF, "member function pointer conversions");
	return GetBogusMemberPointer(CGM, E->getType());
	}

	llvm::Constant CGCXXABI::EmitMemberPointerConversion(const CastExpr E,
	llvm::Constant *Src) {
	return GetBogusMemberPointer(CGM, E->getType());
	}

	llvm::Value *
	CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
	llvm::Value *L,
	llvm::Value *R,
	const MemberPointerType *MPT,
	bool Inequality) {
	ErrorUnsupportedABI(CGF, "member function pointer comparison");
	return CGF.Builder.getFalse();
	}

	llvm::Value *
	CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
	llvm::Value *MemPtr,
	const MemberPointerType *MPT) {
	ErrorUnsupportedABI(CGF, "member function pointer null testing");
	return CGF.Builder.getFalse();
	}

	llvm::Constant *
	CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
	return GetBogusMemberPointer(CGM, QualType(MPT, 0));
	}

	llvm::Constant CGCXXABI::EmitMemberPointer(const CXXMethodDecl MD) {
	return GetBogusMemberPointer(CGM,
	CGM.getContext().getMemberPointerType(MD->getType(),
	MD->getParent()->getTypeForDecl()));
	}

	llvm::Constant CGCXXABI::EmitMemberDataPointer(const MemberPointerType MPT,
	CharUnits offset) {
	return GetBogusMemberPointer(CGM, QualType(MPT, 0));
	}

	llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) {
	return GetBogusMemberPointer(CGM, MPT);
	}

	bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
	// Fake answer.
	return true;
	}

	void CGCXXABI::BuildThisParam(CodeGenFunction &CGF, FunctionArgList &params) {
	const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());

	// FIXME: I'm not entirely sure I like using a fake decl just for code
	// generation. Maybe we can come up with a better way?
	ImplicitParamDecl *ThisDecl
	= ImplicitParamDecl::Create(CGM.getContext(), 0, MD->getLocation(),
	&CGM.getContext().Idents.get("this"),
	MD->getThisType(CGM.getContext()));
	params.push_back(ThisDecl);
	getThisDecl(CGF) = ThisDecl;
	}

	void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
	/// Initialize the 'this' slot.
	assert(getThisDecl(CGF) && "no 'this' variable for function");
	getThisValue(CGF)
	= CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
	"this");
	}

	void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
	RValue RV, QualType ResultType) {
	CGF.EmitReturnOfRValue(RV, ResultType);
	}

	CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
	if (!requiresArrayCookie(expr))
	return CharUnits::Zero();
	return getArrayCookieSizeImpl(expr->getAllocatedType());
	}

	CharUnits CGCXXABI::getArrayCookieSizeImpl(QualType elementType) {
	// BOGUS
	return CharUnits::Zero();
	}

	llvm::Value *CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
	llvm::Value *NewPtr,
	llvm::Value *NumElements,
	const CXXNewExpr *expr,
	QualType ElementType) {
	// Should never be called.
	ErrorUnsupportedABI(CGF, "array cookie initialization");
	return 0;
	}

	bool CGCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
	QualType elementType) {
	// If the class's usual deallocation function takes two arguments,
	// it needs a cookie.
	if (expr->doesUsualArrayDeleteWantSize())
	return true;

	return elementType.isDestructedType();
	}

	bool CGCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
	// If the class's usual deallocation function takes two arguments,
	// it needs a cookie.
	if (expr->doesUsualArrayDeleteWantSize())
	return true;

	return expr->getAllocatedType().isDestructedType();
	}

	void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *ptr,
	const CXXDeleteExpr *expr, QualType eltTy,
	llvm::Value *&numElements,
	llvm::Value *&allocPtr, CharUnits &cookieSize) {
	// Derive a char* in the same address space as the pointer.
	unsigned AS = ptr->getType()->getPointerAddressSpace();
	llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS);
	ptr = CGF.Builder.CreateBitCast(ptr, charPtrTy);

	// If we don't need an array cookie, bail out early.
	if (!requiresArrayCookie(expr, eltTy)) {
	allocPtr = ptr;
	numElements = 0;
	cookieSize = CharUnits::Zero();
	return;
	}

	cookieSize = getArrayCookieSizeImpl(eltTy);
	allocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(ptr,
	-cookieSize.getQuantity());
	numElements = readArrayCookieImpl(CGF, allocPtr, cookieSize);
	}

	llvm::Value *CGCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
	llvm::Value *ptr,
	CharUnits cookieSize) {
	ErrorUnsupportedABI(CGF, "reading a new[] cookie");
	return llvm::ConstantInt::get(CGF.SizeTy, 0);
	}

	void CGCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
	const VarDecl &D,
	llvm::GlobalVariable *GV,
	bool PerformInit) {
	ErrorUnsupportedABI(CGF, "static local variable initialization");
	}

	void CGCXXABI::registerGlobalDtor(CodeGenFunction &CGF,
	llvm::Constant *dtor,
	llvm::Constant *addr) {
	// The default behavior is to use atexit.
	CGF.registerGlobalDtorWithAtExit(dtor, addr);
	}

	/// Returns the adjustment, in bytes, required for the given
	/// member-pointer operation. Returns null if no adjustment is
	/// required.
	llvm::Constant CGCXXABI::getMemberPointerAdjustment(const CastExpr E) {
	assert(E->getCastKind() == CK_DerivedToBaseMemberPointer \|\|
	E->getCastKind() == CK_BaseToDerivedMemberPointer);

	QualType derivedType;
	if (E->getCastKind() == CK_DerivedToBaseMemberPointer)
	derivedType = E->getSubExpr()->getType();
	else
	derivedType = E->getType();

	const CXXRecordDecl *derivedClass =
	derivedType->castAs<MemberPointerType>()->getClass()->getAsCXXRecordDecl();

	return CGM.GetNonVirtualBaseClassOffset(derivedClass,
	E->path_begin(),
	E->path_end());
	}

	llvm::BasicBlock *CGCXXABI::EmitCtorCompleteObjectHandler(
	CodeGenFunction &CGF) {
	if (CGM.getTarget().getCXXABI().hasConstructorVariants())
	llvm_unreachable("shouldn't be called in this ABI");

	ErrorUnsupportedABI(CGF, "complete object detection in ctor");
	return 0;
	}