forked from OSchip/llvm-project
135 lines
4.6 KiB
C++
135 lines
4.6 KiB
C++
//===--- CGCXXClass.cpp - Emit LLVM Code for C++ classes ------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with C++ code generation of classes
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenFunction.h"
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#include "clang/AST/RecordLayout.h"
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using namespace clang;
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using namespace CodeGen;
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static bool
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GetNestedPaths(llvm::SmallVectorImpl<const CXXRecordDecl *> &NestedBasePaths,
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const CXXRecordDecl *ClassDecl,
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const CXXRecordDecl *BaseClassDecl) {
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for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
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e = ClassDecl->bases_end(); i != e; ++i) {
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if (i->isVirtual())
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continue;
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const CXXRecordDecl *Base =
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cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
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if (Base == BaseClassDecl) {
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NestedBasePaths.push_back(BaseClassDecl);
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return true;
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}
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}
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// BaseClassDecl not an immediate base of ClassDecl.
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for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
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e = ClassDecl->bases_end(); i != e; ++i) {
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if (i->isVirtual())
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continue;
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const CXXRecordDecl *Base =
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cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
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if (GetNestedPaths(NestedBasePaths, Base, BaseClassDecl)) {
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NestedBasePaths.push_back(Base);
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return true;
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}
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}
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return false;
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}
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static uint64_t ComputeBaseClassOffset(ASTContext &Context,
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const CXXRecordDecl *ClassDecl,
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const CXXRecordDecl *BaseClassDecl) {
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uint64_t Offset = 0;
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llvm::SmallVector<const CXXRecordDecl *, 16> NestedBasePaths;
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GetNestedPaths(NestedBasePaths, ClassDecl, BaseClassDecl);
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assert(NestedBasePaths.size() > 0 &&
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"AddressCXXOfBaseClass - inheritence path failed");
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NestedBasePaths.push_back(ClassDecl);
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for (unsigned i = NestedBasePaths.size() - 1; i > 0; i--) {
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const CXXRecordDecl *DerivedClass = NestedBasePaths[i];
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const CXXRecordDecl *BaseClass = NestedBasePaths[i-1];
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const ASTRecordLayout &Layout =
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Context.getASTRecordLayout(DerivedClass);
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Offset += Layout.getBaseClassOffset(BaseClass) / 8;
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}
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return Offset;
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}
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llvm::Value *
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CodeGenFunction::GetAddressCXXOfBaseClass(llvm::Value *BaseValue,
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const CXXRecordDecl *ClassDecl,
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const CXXRecordDecl *BaseClassDecl,
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bool NullCheckValue) {
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if (ClassDecl == BaseClassDecl)
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return BaseValue;
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uint64_t Offset = ComputeBaseClassOffset(getContext(),
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ClassDecl, BaseClassDecl);
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llvm::BasicBlock *CastNull = 0;
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llvm::BasicBlock *CastNotNull = 0;
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llvm::BasicBlock *CastEnd = 0;
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if (NullCheckValue) {
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CastNull = createBasicBlock("cast.null");
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CastNotNull = createBasicBlock("cast.notnull");
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CastEnd = createBasicBlock("cast.end");
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llvm::Value *IsNull =
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Builder.CreateICmpEQ(BaseValue,
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llvm::Constant::getNullValue(BaseValue->getType()));
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Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
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EmitBlock(CastNotNull);
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}
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const llvm::Type *LongTy =
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CGM.getTypes().ConvertType(CGM.getContext().LongTy);
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const llvm::Type *Int8PtrTy =
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llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
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llvm::Value *OffsetVal = llvm::ConstantInt::get(LongTy, Offset);
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// Apply the offset.
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BaseValue = Builder.CreateBitCast(BaseValue, Int8PtrTy);
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BaseValue = Builder.CreateGEP(BaseValue, OffsetVal, "add.ptr");
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QualType BTy =
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getContext().getCanonicalType(
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getContext().getTypeDeclType(const_cast<CXXRecordDecl*>(BaseClassDecl)));
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// Cast back.
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const llvm::Type *BasePtr = llvm::PointerType::getUnqual(ConvertType(BTy));
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BaseValue = Builder.CreateBitCast(BaseValue, BasePtr);
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if (NullCheckValue) {
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Builder.CreateBr(CastEnd);
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EmitBlock(CastNull);
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Builder.CreateBr(CastEnd);
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EmitBlock(CastEnd);
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llvm::PHINode *PHI = Builder.CreatePHI(BaseValue->getType());
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PHI->reserveOperandSpace(2);
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PHI->addIncoming(BaseValue, CastNotNull);
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PHI->addIncoming(llvm::Constant::getNullValue(BaseValue->getType()),
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CastNull);
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BaseValue = PHI;
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}
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return BaseValue;
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}
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