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-rw-r--r--lib/CodeGen/CGClass.cpp235
1 files changed, 235 insertions, 0 deletions
diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
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+++ b/lib/CodeGen/CGClass.cpp
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+//===--- CGClass.cpp - Emit LLVM Code for C++ classes ---------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code dealing with C++ code generation of classes
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenFunction.h"
+#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/RecordLayout.h"
+
+using namespace clang;
+using namespace CodeGen;
+
+static uint64_t
+ComputeNonVirtualBaseClassOffset(ASTContext &Context, CXXBasePaths &Paths,
+ unsigned Start) {
+ uint64_t Offset = 0;
+
+ const CXXBasePath &Path = Paths.front();
+ for (unsigned i = Start, e = Path.size(); i != e; ++i) {
+ const CXXBasePathElement& Element = Path[i];
+
+ // Get the layout.
+ const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class);
+
+ const CXXBaseSpecifier *BS = Element.Base;
+ assert(!BS->isVirtual() && "Should not see virtual bases here!");
+
+ const CXXRecordDecl *Base =
+ cast<CXXRecordDecl>(BS->getType()->getAs<RecordType>()->getDecl());
+
+ // Add the offset.
+ Offset += Layout.getBaseClassOffset(Base) / 8;
+ }
+
+ return Offset;
+}
+
+llvm::Constant *
+CodeGenModule::GetCXXBaseClassOffset(const CXXRecordDecl *ClassDecl,
+ const CXXRecordDecl *BaseClassDecl) {
+ if (ClassDecl == BaseClassDecl)
+ return 0;
+
+ CXXBasePaths Paths(/*FindAmbiguities=*/false,
+ /*RecordPaths=*/true, /*DetectVirtual=*/false);
+ if (!const_cast<CXXRecordDecl *>(ClassDecl)->
+ isDerivedFrom(const_cast<CXXRecordDecl *>(BaseClassDecl), Paths)) {
+ assert(false && "Class must be derived from the passed in base class!");
+ return 0;
+ }
+
+ uint64_t Offset = ComputeNonVirtualBaseClassOffset(getContext(), Paths, 0);
+ if (!Offset)
+ return 0;
+
+ const llvm::Type *PtrDiffTy =
+ Types.ConvertType(getContext().getPointerDiffType());
+
+ return llvm::ConstantInt::get(PtrDiffTy, Offset);
+}
+
+static llvm::Value *GetCXXBaseClassOffset(CodeGenFunction &CGF,
+ llvm::Value *BaseValue,
+ const CXXRecordDecl *ClassDecl,
+ const CXXRecordDecl *BaseClassDecl) {
+ CXXBasePaths Paths(/*FindAmbiguities=*/false,
+ /*RecordPaths=*/true, /*DetectVirtual=*/false);
+ if (!const_cast<CXXRecordDecl *>(ClassDecl)->
+ isDerivedFrom(const_cast<CXXRecordDecl *>(BaseClassDecl), Paths)) {
+ assert(false && "Class must be derived from the passed in base class!");
+ return 0;
+ }
+
+ unsigned Start = 0;
+ llvm::Value *VirtualOffset = 0;
+
+ const CXXBasePath &Path = Paths.front();
+ const CXXRecordDecl *VBase = 0;
+ for (unsigned i = 0, e = Path.size(); i != e; ++i) {
+ const CXXBasePathElement& Element = Path[i];
+ if (Element.Base->isVirtual()) {
+ Start = i+1;
+ QualType VBaseType = Element.Base->getType();
+ VBase = cast<CXXRecordDecl>(VBaseType->getAs<RecordType>()->getDecl());
+ }
+ }
+ if (VBase)
+ VirtualOffset =
+ CGF.GetVirtualCXXBaseClassOffset(BaseValue, ClassDecl, VBase);
+
+ uint64_t Offset =
+ ComputeNonVirtualBaseClassOffset(CGF.getContext(), Paths, Start);
+
+ if (!Offset)
+ return VirtualOffset;
+
+ const llvm::Type *PtrDiffTy =
+ CGF.ConvertType(CGF.getContext().getPointerDiffType());
+ llvm::Value *NonVirtualOffset = llvm::ConstantInt::get(PtrDiffTy, Offset);
+
+ if (VirtualOffset)
+ return CGF.Builder.CreateAdd(VirtualOffset, NonVirtualOffset);
+
+ return NonVirtualOffset;
+}
+
+llvm::Value *
+CodeGenFunction::GetAddressOfBaseClass(llvm::Value *Value,
+ const CXXRecordDecl *ClassDecl,
+ const CXXRecordDecl *BaseClassDecl,
+ bool NullCheckValue) {
+ QualType BTy =
+ getContext().getCanonicalType(
+ getContext().getTypeDeclType(const_cast<CXXRecordDecl*>(BaseClassDecl)));
+ const llvm::Type *BasePtrTy = llvm::PointerType::getUnqual(ConvertType(BTy));
+
+ if (ClassDecl == BaseClassDecl) {
+ // Just cast back.
+ return Builder.CreateBitCast(Value, BasePtrTy);
+ }
+
+ llvm::BasicBlock *CastNull = 0;
+ llvm::BasicBlock *CastNotNull = 0;
+ llvm::BasicBlock *CastEnd = 0;
+
+ if (NullCheckValue) {
+ CastNull = createBasicBlock("cast.null");
+ CastNotNull = createBasicBlock("cast.notnull");
+ CastEnd = createBasicBlock("cast.end");
+
+ llvm::Value *IsNull =
+ Builder.CreateICmpEQ(Value,
+ llvm::Constant::getNullValue(Value->getType()));
+ Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
+ EmitBlock(CastNotNull);
+ }
+
+ const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
+
+ llvm::Value *Offset =
+ GetCXXBaseClassOffset(*this, Value, ClassDecl, BaseClassDecl);
+
+ if (Offset) {
+ // Apply the offset.
+ Value = Builder.CreateBitCast(Value, Int8PtrTy);
+ Value = Builder.CreateGEP(Value, Offset, "add.ptr");
+ }
+
+ // Cast back.
+ Value = Builder.CreateBitCast(Value, BasePtrTy);
+
+ if (NullCheckValue) {
+ Builder.CreateBr(CastEnd);
+ EmitBlock(CastNull);
+ Builder.CreateBr(CastEnd);
+ EmitBlock(CastEnd);
+
+ llvm::PHINode *PHI = Builder.CreatePHI(Value->getType());
+ PHI->reserveOperandSpace(2);
+ PHI->addIncoming(Value, CastNotNull);
+ PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()),
+ CastNull);
+ Value = PHI;
+ }
+
+ return Value;
+}
+
+llvm::Value *
+CodeGenFunction::GetAddressOfDerivedClass(llvm::Value *Value,
+ const CXXRecordDecl *ClassDecl,
+ const CXXRecordDecl *DerivedClassDecl,
+ bool NullCheckValue) {
+ QualType DerivedTy =
+ getContext().getCanonicalType(
+ getContext().getTypeDeclType(const_cast<CXXRecordDecl*>(DerivedClassDecl)));
+ const llvm::Type *DerivedPtrTy = ConvertType(DerivedTy)->getPointerTo();
+
+ if (ClassDecl == DerivedClassDecl) {
+ // Just cast back.
+ return Builder.CreateBitCast(Value, DerivedPtrTy);
+ }
+
+ llvm::BasicBlock *CastNull = 0;
+ llvm::BasicBlock *CastNotNull = 0;
+ llvm::BasicBlock *CastEnd = 0;
+
+ if (NullCheckValue) {
+ CastNull = createBasicBlock("cast.null");
+ CastNotNull = createBasicBlock("cast.notnull");
+ CastEnd = createBasicBlock("cast.end");
+
+ llvm::Value *IsNull =
+ Builder.CreateICmpEQ(Value,
+ llvm::Constant::getNullValue(Value->getType()));
+ Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
+ EmitBlock(CastNotNull);
+ }
+
+ llvm::Value *Offset = GetCXXBaseClassOffset(*this, Value, DerivedClassDecl,
+ ClassDecl);
+ if (Offset) {
+ // Apply the offset.
+ Value = Builder.CreatePtrToInt(Value, Offset->getType());
+ Value = Builder.CreateSub(Value, Offset);
+ Value = Builder.CreateIntToPtr(Value, DerivedPtrTy);
+ } else {
+ // Just cast.
+ Value = Builder.CreateBitCast(Value, DerivedPtrTy);
+ }
+
+ if (NullCheckValue) {
+ Builder.CreateBr(CastEnd);
+ EmitBlock(CastNull);
+ Builder.CreateBr(CastEnd);
+ EmitBlock(CastEnd);
+
+ llvm::PHINode *PHI = Builder.CreatePHI(Value->getType());
+ PHI->reserveOperandSpace(2);
+ PHI->addIncoming(Value, CastNotNull);
+ PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()),
+ CastNull);
+ Value = PHI;
+ }
+
+ return Value;
+}
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