| //===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This provides C++ code generation targeting the Microsoft Visual C++ ABI. |
| // The class in this file generates structures that follow the Microsoft |
| // Visual C++ ABI, which is actually not very well documented at all outside |
| // of Microsoft. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CGCXXABI.h" |
| #include "CodeGenModule.h" |
| #include "clang/AST/Decl.h" |
| #include "clang/AST/DeclCXX.h" |
| |
| using namespace clang; |
| using namespace CodeGen; |
| |
| namespace { |
| |
| class MicrosoftCXXABI : public CGCXXABI { |
| public: |
| MicrosoftCXXABI(CodeGenModule &CGM) : CGCXXABI(CGM) {} |
| |
| void BuildConstructorSignature(const CXXConstructorDecl *Ctor, |
| CXXCtorType Type, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys) { |
| // 'this' is already in place |
| // TODO: 'for base' flag |
| } |
| |
| void BuildDestructorSignature(const CXXDestructorDecl *Ctor, |
| CXXDtorType Type, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys) { |
| // 'this' is already in place |
| // TODO: 'for base' flag |
| } |
| |
| void BuildInstanceFunctionParams(CodeGenFunction &CGF, |
| QualType &ResTy, |
| FunctionArgList &Params) { |
| BuildThisParam(CGF, Params); |
| // TODO: 'for base' flag |
| } |
| |
| void EmitInstanceFunctionProlog(CodeGenFunction &CGF) { |
| EmitThisParam(CGF); |
| // TODO: 'for base' flag |
| } |
| |
| void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, |
| llvm::GlobalVariable *DeclPtr, |
| bool PerformInit); |
| |
| |
| // ==== Notes on array cookies ========= |
| // |
| // MSVC seems to only use cookies when the class has a destructor; a |
| // two-argument usual array deallocation function isn't sufficient. |
| // |
| // For example, this code prints "100" and "1": |
| // struct A { |
| // char x; |
| // void *operator new[](size_t sz) { |
| // printf("%u\n", sz); |
| // return malloc(sz); |
| // } |
| // void operator delete[](void *p, size_t sz) { |
| // printf("%u\n", sz); |
| // free(p); |
| // } |
| // }; |
| // int main() { |
| // A *p = new A[100]; |
| // delete[] p; |
| // } |
| // Whereas it prints "104" and "104" if you give A a destructor. |
| |
| bool requiresArrayCookie(const CXXDeleteExpr *expr, QualType elementType); |
| bool requiresArrayCookie(const CXXNewExpr *expr); |
| CharUnits getArrayCookieSizeImpl(QualType type); |
| llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *NewPtr, |
| llvm::Value *NumElements, |
| const CXXNewExpr *expr, |
| QualType ElementType); |
| llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, |
| llvm::Value *allocPtr, |
| CharUnits cookieSize); |
| }; |
| |
| } |
| |
| bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr, |
| QualType elementType) { |
| // Microsoft seems to completely ignore the possibility of a |
| // two-argument usual deallocation function. |
| return elementType.isDestructedType(); |
| } |
| |
| bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) { |
| // Microsoft seems to completely ignore the possibility of a |
| // two-argument usual deallocation function. |
| return expr->getAllocatedType().isDestructedType(); |
| } |
| |
| CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) { |
| // The array cookie is always a size_t; we then pad that out to the |
| // alignment of the element type. |
| ASTContext &Ctx = getContext(); |
| return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()), |
| Ctx.getTypeAlignInChars(type)); |
| } |
| |
| llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, |
| llvm::Value *allocPtr, |
| CharUnits cookieSize) { |
| unsigned AS = cast<llvm::PointerType>(allocPtr->getType())->getAddressSpace(); |
| llvm::Value *numElementsPtr = |
| CGF.Builder.CreateBitCast(allocPtr, CGF.SizeTy->getPointerTo(AS)); |
| return CGF.Builder.CreateLoad(numElementsPtr); |
| } |
| |
| llvm::Value* MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *newPtr, |
| llvm::Value *numElements, |
| const CXXNewExpr *expr, |
| QualType elementType) { |
| assert(requiresArrayCookie(expr)); |
| |
| // The size of the cookie. |
| CharUnits cookieSize = getArrayCookieSizeImpl(elementType); |
| |
| // Compute an offset to the cookie. |
| llvm::Value *cookiePtr = newPtr; |
| |
| // Write the number of elements into the appropriate slot. |
| unsigned AS = cast<llvm::PointerType>(newPtr->getType())->getAddressSpace(); |
| llvm::Value *numElementsPtr |
| = CGF.Builder.CreateBitCast(cookiePtr, CGF.SizeTy->getPointerTo(AS)); |
| CGF.Builder.CreateStore(numElements, numElementsPtr); |
| |
| // Finally, compute a pointer to the actual data buffer by skipping |
| // over the cookie completely. |
| return CGF.Builder.CreateConstInBoundsGEP1_64(newPtr, |
| cookieSize.getQuantity()); |
| } |
| |
| void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, |
| llvm::GlobalVariable *DeclPtr, |
| bool PerformInit) { |
| // FIXME: this code was only tested for global initialization. |
| // Not sure whether we want thread-safe static local variables as VS |
| // doesn't make them thread-safe. |
| |
| // Emit the initializer and add a global destructor if appropriate. |
| CGF.EmitCXXGlobalVarDeclInit(D, DeclPtr, PerformInit); |
| } |
| |
| CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) { |
| return new MicrosoftCXXABI(CGM); |
| } |
| |