diff options
Diffstat (limited to 'clang/lib/CodeGen/ItaniumCXXABI.cpp')
| -rw-r--r-- | clang/lib/CodeGen/ItaniumCXXABI.cpp | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp index be8dac140ed..38d49d134e9 100644 --- a/clang/lib/CodeGen/ItaniumCXXABI.cpp +++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp @@ -25,6 +25,7 @@ #include "CodeGenModule.h" #include "clang/AST/Mangle.h" #include "clang/AST/Type.h" +#include "llvm/IR/CallSite.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/Value.h" @@ -108,6 +109,26 @@ public: llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF, llvm::Value *ptr, QualType type) override; + bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override; + void EmitBadTypeidCall(CodeGenFunction &CGF) override; + llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy, + llvm::Value *ThisPtr, + llvm::Type *StdTypeInfoPtrTy) override; + + bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr, + QualType SrcRecordTy) override; + + llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, llvm::Value *Value, + QualType SrcRecordTy, QualType DestTy, + QualType DestRecordTy, + llvm::BasicBlock *CastEnd) override; + + llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, llvm::Value *Value, + QualType SrcRecordTy, + QualType DestTy) override; + + bool EmitBadCastCall(CodeGenFunction &CGF) override; + llvm::Value * GetVirtualBaseClassOffset(CodeGenFunction &CGF, llvm::Value *This, const CXXRecordDecl *ClassDecl, @@ -800,6 +821,194 @@ llvm::Value *ItaniumCXXABI::adjustToCompleteObject(CodeGenFunction &CGF, return CGF.Builder.CreateInBoundsGEP(ptr, offset); } +static llvm::Constant *getItaniumDynamicCastFn(CodeGenFunction &CGF) { + // void *__dynamic_cast(const void *sub, + // const abi::__class_type_info *src, + // const abi::__class_type_info *dst, + // std::ptrdiff_t src2dst_offset); + + llvm::Type *Int8PtrTy = CGF.Int8PtrTy; + llvm::Type *PtrDiffTy = + CGF.ConvertType(CGF.getContext().getPointerDiffType()); + + llvm::Type *Args[4] = { Int8PtrTy, Int8PtrTy, Int8PtrTy, PtrDiffTy }; + + llvm::FunctionType *FTy = llvm::FunctionType::get(Int8PtrTy, Args, false); + + // Mark the function as nounwind readonly. + llvm::Attribute::AttrKind FuncAttrs[] = { llvm::Attribute::NoUnwind, + llvm::Attribute::ReadOnly }; + llvm::AttributeSet Attrs = llvm::AttributeSet::get( + CGF.getLLVMContext(), llvm::AttributeSet::FunctionIndex, FuncAttrs); + + return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast", Attrs); +} + +static llvm::Constant *getBadCastFn(CodeGenFunction &CGF) { + // void __cxa_bad_cast(); + llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false); + return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_cast"); +} + +/// \brief Compute the src2dst_offset hint as described in the +/// Itanium C++ ABI [2.9.7] +static CharUnits computeOffsetHint(ASTContext &Context, + const CXXRecordDecl *Src, + const CXXRecordDecl *Dst) { + CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, + /*DetectVirtual=*/false); + + // If Dst is not derived from Src we can skip the whole computation below and + // return that Src is not a public base of Dst. Record all inheritance paths. + if (!Dst->isDerivedFrom(Src, Paths)) + return CharUnits::fromQuantity(-2ULL); + + unsigned NumPublicPaths = 0; + CharUnits Offset; + + // Now walk all possible inheritance paths. + for (CXXBasePaths::paths_iterator I = Paths.begin(), E = Paths.end(); I != E; + ++I) { + if (I->Access != AS_public) // Ignore non-public inheritance. + continue; + + ++NumPublicPaths; + + for (CXXBasePath::iterator J = I->begin(), JE = I->end(); J != JE; ++J) { + // If the path contains a virtual base class we can't give any hint. + // -1: no hint. + if (J->Base->isVirtual()) + return CharUnits::fromQuantity(-1ULL); + + if (NumPublicPaths > 1) // Won't use offsets, skip computation. + continue; + + // Accumulate the base class offsets. + const ASTRecordLayout &L = Context.getASTRecordLayout(J->Class); + Offset += L.getBaseClassOffset(J->Base->getType()->getAsCXXRecordDecl()); + } + } + + // -2: Src is not a public base of Dst. + if (NumPublicPaths == 0) + return CharUnits::fromQuantity(-2ULL); + + // -3: Src is a multiple public base type but never a virtual base type. + if (NumPublicPaths > 1) + return CharUnits::fromQuantity(-3ULL); + + // Otherwise, the Src type is a unique public nonvirtual base type of Dst. + // Return the offset of Src from the origin of Dst. + return Offset; +} + +static llvm::Constant *getBadTypeidFn(CodeGenFunction &CGF) { + // void __cxa_bad_typeid(); + llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false); + + return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_typeid"); +} + +bool ItaniumCXXABI::shouldTypeidBeNullChecked(bool IsDeref, + QualType SrcRecordTy) { + return IsDeref; +} + +void ItaniumCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) { + llvm::Value *Fn = getBadTypeidFn(CGF); + CGF.EmitRuntimeCallOrInvoke(Fn).setDoesNotReturn(); + CGF.Builder.CreateUnreachable(); +} + +llvm::Value *ItaniumCXXABI::EmitTypeid(CodeGenFunction &CGF, + QualType SrcRecordTy, + llvm::Value *ThisPtr, + llvm::Type *StdTypeInfoPtrTy) { + llvm::Value *Value = + CGF.GetVTablePtr(ThisPtr, StdTypeInfoPtrTy->getPointerTo()); + + // Load the type info. + Value = CGF.Builder.CreateConstInBoundsGEP1_64(Value, -1ULL); + return CGF.Builder.CreateLoad(Value); +} + +bool ItaniumCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr, + QualType SrcRecordTy) { + return SrcIsPtr; +} + +llvm::Value *ItaniumCXXABI::EmitDynamicCastCall( + CodeGenFunction &CGF, llvm::Value *Value, QualType SrcRecordTy, + QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) { + llvm::Type *PtrDiffLTy = + CGF.ConvertType(CGF.getContext().getPointerDiffType()); + llvm::Type *DestLTy = CGF.ConvertType(DestTy); + + llvm::Value *SrcRTTI = + CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType()); + llvm::Value *DestRTTI = + CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType()); + + // Compute the offset hint. + const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); + const CXXRecordDecl *DestDecl = DestRecordTy->getAsCXXRecordDecl(); + llvm::Value *OffsetHint = llvm::ConstantInt::get( + PtrDiffLTy, + computeOffsetHint(CGF.getContext(), SrcDecl, DestDecl).getQuantity()); + + // Emit the call to __dynamic_cast. + Value = CGF.EmitCastToVoidPtr(Value); + + llvm::Value *args[] = {Value, SrcRTTI, DestRTTI, OffsetHint}; + Value = CGF.EmitNounwindRuntimeCall(getItaniumDynamicCastFn(CGF), args); + Value = CGF.Builder.CreateBitCast(Value, DestLTy); + + /// C++ [expr.dynamic.cast]p9: + /// A failed cast to reference type throws std::bad_cast + if (DestTy->isReferenceType()) { + llvm::BasicBlock *BadCastBlock = + CGF.createBasicBlock("dynamic_cast.bad_cast"); + + llvm::Value *IsNull = CGF.Builder.CreateIsNull(Value); + CGF.Builder.CreateCondBr(IsNull, BadCastBlock, CastEnd); + + CGF.EmitBlock(BadCastBlock); + EmitBadCastCall(CGF); + } + + return Value; +} + +llvm::Value *ItaniumCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF, + llvm::Value *Value, + QualType SrcRecordTy, + QualType DestTy) { + llvm::Type *PtrDiffLTy = + CGF.ConvertType(CGF.getContext().getPointerDiffType()); + llvm::Type *DestLTy = CGF.ConvertType(DestTy); + + // Get the vtable pointer. + llvm::Value *VTable = CGF.GetVTablePtr(Value, PtrDiffLTy->getPointerTo()); + + // Get the offset-to-top from the vtable. + llvm::Value *OffsetToTop = + CGF.Builder.CreateConstInBoundsGEP1_64(VTable, -2ULL); + OffsetToTop = CGF.Builder.CreateLoad(OffsetToTop, "offset.to.top"); + + // Finally, add the offset to the pointer. + Value = CGF.EmitCastToVoidPtr(Value); + Value = CGF.Builder.CreateInBoundsGEP(Value, OffsetToTop); + + return CGF.Builder.CreateBitCast(Value, DestLTy); +} + +bool ItaniumCXXABI::EmitBadCastCall(CodeGenFunction &CGF) { + llvm::Value *Fn = getBadCastFn(CGF); + CGF.EmitRuntimeCallOrInvoke(Fn).setDoesNotReturn(); + CGF.Builder.CreateUnreachable(); + return true; +} + llvm::Value * ItaniumCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF, llvm::Value *This, |
