| //===------- ItaniumCXXABI.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 Itanium C++ ABI. The class |
| // in this file generates structures that follow the Itanium C++ ABI, which is |
| // documented at: |
| // http://www.codesourcery.com/public/cxx-abi/abi.html |
| // http://www.codesourcery.com/public/cxx-abi/abi-eh.html |
| // |
| // It also supports the closely-related ARM ABI, documented at: |
| // http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CGCXXABI.h" |
| #include "CGRecordLayout.h" |
| #include "CodeGenFunction.h" |
| #include "CodeGenModule.h" |
| #include <clang/AST/Mangle.h> |
| #include <clang/AST/Type.h> |
| #include <llvm/Intrinsics.h> |
| #include <llvm/Target/TargetData.h> |
| #include <llvm/Value.h> |
| |
| using namespace clang; |
| using namespace CodeGen; |
| |
| namespace { |
| class ItaniumCXXABI : public CodeGen::CGCXXABI { |
| private: |
| llvm::IntegerType *PtrDiffTy; |
| protected: |
| bool IsARM; |
| |
| // It's a little silly for us to cache this. |
| llvm::IntegerType *getPtrDiffTy() { |
| if (!PtrDiffTy) { |
| QualType T = getContext().getPointerDiffType(); |
| llvm::Type *Ty = CGM.getTypes().ConvertType(T); |
| PtrDiffTy = cast<llvm::IntegerType>(Ty); |
| } |
| return PtrDiffTy; |
| } |
| |
| bool NeedsArrayCookie(const CXXNewExpr *expr); |
| bool NeedsArrayCookie(const CXXDeleteExpr *expr, |
| QualType elementType); |
| |
| public: |
| ItaniumCXXABI(CodeGen::CodeGenModule &CGM, bool IsARM = false) : |
| CGCXXABI(CGM), PtrDiffTy(0), IsARM(IsARM) { } |
| |
| bool isZeroInitializable(const MemberPointerType *MPT); |
| |
| llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT); |
| |
| llvm::Value *EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, |
| llvm::Value *&This, |
| llvm::Value *MemFnPtr, |
| const MemberPointerType *MPT); |
| |
| llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, |
| llvm::Value *Base, |
| llvm::Value *MemPtr, |
| const MemberPointerType *MPT); |
| |
| llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, |
| const CastExpr *E, |
| llvm::Value *Src); |
| |
| llvm::Constant *EmitMemberPointerConversion(llvm::Constant *C, |
| const CastExpr *E); |
| |
| llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT); |
| |
| llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD); |
| llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, |
| CharUnits offset); |
| llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT); |
| llvm::Constant *BuildMemberPointer(const CXXMethodDecl *MD, |
| CharUnits ThisAdjustment); |
| |
| llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF, |
| llvm::Value *L, |
| llvm::Value *R, |
| const MemberPointerType *MPT, |
| bool Inequality); |
| |
| llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF, |
| llvm::Value *Addr, |
| const MemberPointerType *MPT); |
| |
| void BuildConstructorSignature(const CXXConstructorDecl *Ctor, |
| CXXCtorType T, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys); |
| |
| void BuildDestructorSignature(const CXXDestructorDecl *Dtor, |
| CXXDtorType T, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys); |
| |
| void BuildInstanceFunctionParams(CodeGenFunction &CGF, |
| QualType &ResTy, |
| FunctionArgList &Params); |
| |
| void EmitInstanceFunctionProlog(CodeGenFunction &CGF); |
| |
| CharUnits GetArrayCookieSize(const CXXNewExpr *expr); |
| llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *NewPtr, |
| llvm::Value *NumElements, |
| const CXXNewExpr *expr, |
| QualType ElementType); |
| void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, |
| const CXXDeleteExpr *expr, |
| QualType ElementType, llvm::Value *&NumElements, |
| llvm::Value *&AllocPtr, CharUnits &CookieSize); |
| |
| void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, |
| llvm::GlobalVariable *DeclPtr); |
| }; |
| |
| class ARMCXXABI : public ItaniumCXXABI { |
| public: |
| ARMCXXABI(CodeGen::CodeGenModule &CGM) : ItaniumCXXABI(CGM, /*ARM*/ true) {} |
| |
| void BuildConstructorSignature(const CXXConstructorDecl *Ctor, |
| CXXCtorType T, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys); |
| |
| void BuildDestructorSignature(const CXXDestructorDecl *Dtor, |
| CXXDtorType T, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys); |
| |
| void BuildInstanceFunctionParams(CodeGenFunction &CGF, |
| QualType &ResTy, |
| FunctionArgList &Params); |
| |
| void EmitInstanceFunctionProlog(CodeGenFunction &CGF); |
| |
| void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV, QualType ResTy); |
| |
| CharUnits GetArrayCookieSize(const CXXNewExpr *expr); |
| llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *NewPtr, |
| llvm::Value *NumElements, |
| const CXXNewExpr *expr, |
| QualType ElementType); |
| void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, |
| const CXXDeleteExpr *expr, |
| QualType ElementType, llvm::Value *&NumElements, |
| llvm::Value *&AllocPtr, CharUnits &CookieSize); |
| |
| private: |
| /// \brief Returns true if the given instance method is one of the |
| /// kinds that the ARM ABI says returns 'this'. |
| static bool HasThisReturn(GlobalDecl GD) { |
| const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); |
| return ((isa<CXXDestructorDecl>(MD) && GD.getDtorType() != Dtor_Deleting) || |
| (isa<CXXConstructorDecl>(MD))); |
| } |
| }; |
| } |
| |
| CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) { |
| return new ItaniumCXXABI(CGM); |
| } |
| |
| CodeGen::CGCXXABI *CodeGen::CreateARMCXXABI(CodeGenModule &CGM) { |
| return new ARMCXXABI(CGM); |
| } |
| |
| llvm::Type * |
| ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { |
| if (MPT->isMemberDataPointer()) |
| return getPtrDiffTy(); |
| return llvm::StructType::get(getPtrDiffTy(), getPtrDiffTy(), NULL); |
| } |
| |
| /// In the Itanium and ARM ABIs, method pointers have the form: |
| /// struct { ptrdiff_t ptr; ptrdiff_t adj; } memptr; |
| /// |
| /// In the Itanium ABI: |
| /// - method pointers are virtual if (memptr.ptr & 1) is nonzero |
| /// - the this-adjustment is (memptr.adj) |
| /// - the virtual offset is (memptr.ptr - 1) |
| /// |
| /// In the ARM ABI: |
| /// - method pointers are virtual if (memptr.adj & 1) is nonzero |
| /// - the this-adjustment is (memptr.adj >> 1) |
| /// - the virtual offset is (memptr.ptr) |
| /// ARM uses 'adj' for the virtual flag because Thumb functions |
| /// may be only single-byte aligned. |
| /// |
| /// If the member is virtual, the adjusted 'this' pointer points |
| /// to a vtable pointer from which the virtual offset is applied. |
| /// |
| /// If the member is non-virtual, memptr.ptr is the address of |
| /// the function to call. |
| llvm::Value * |
| ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, |
| llvm::Value *&This, |
| llvm::Value *MemFnPtr, |
| const MemberPointerType *MPT) { |
| CGBuilderTy &Builder = CGF.Builder; |
| |
| 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().getFunctionInfo(RD, FPT), |
| FPT->isVariadic()); |
| |
| llvm::IntegerType *ptrdiff = getPtrDiffTy(); |
| llvm::Constant *ptrdiff_1 = llvm::ConstantInt::get(ptrdiff, 1); |
| |
| llvm::BasicBlock *FnVirtual = CGF.createBasicBlock("memptr.virtual"); |
| llvm::BasicBlock *FnNonVirtual = CGF.createBasicBlock("memptr.nonvirtual"); |
| llvm::BasicBlock *FnEnd = CGF.createBasicBlock("memptr.end"); |
| |
| // Extract memptr.adj, which is in the second field. |
| llvm::Value *RawAdj = Builder.CreateExtractValue(MemFnPtr, 1, "memptr.adj"); |
| |
| // Compute the true adjustment. |
| llvm::Value *Adj = RawAdj; |
| if (IsARM) |
| Adj = Builder.CreateAShr(Adj, ptrdiff_1, "memptr.adj.shifted"); |
| |
| // Apply the adjustment and cast back to the original struct type |
| // for consistency. |
| llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy()); |
| Ptr = Builder.CreateInBoundsGEP(Ptr, Adj); |
| This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted"); |
| |
| // Load the function pointer. |
| llvm::Value *FnAsInt = Builder.CreateExtractValue(MemFnPtr, 0, "memptr.ptr"); |
| |
| // If the LSB in the function pointer is 1, the function pointer points to |
| // a virtual function. |
| llvm::Value *IsVirtual; |
| if (IsARM) |
| IsVirtual = Builder.CreateAnd(RawAdj, ptrdiff_1); |
| else |
| IsVirtual = Builder.CreateAnd(FnAsInt, ptrdiff_1); |
| IsVirtual = Builder.CreateIsNotNull(IsVirtual, "memptr.isvirtual"); |
| Builder.CreateCondBr(IsVirtual, FnVirtual, FnNonVirtual); |
| |
| // In the virtual path, the adjustment left 'This' pointing to the |
| // vtable of the correct base subobject. The "function pointer" is an |
| // offset within the vtable (+1 for the virtual flag on non-ARM). |
| CGF.EmitBlock(FnVirtual); |
| |
| // Cast the adjusted this to a pointer to vtable pointer and load. |
| llvm::Type *VTableTy = Builder.getInt8PtrTy(); |
| llvm::Value *VTable = Builder.CreateBitCast(This, VTableTy->getPointerTo()); |
| VTable = Builder.CreateLoad(VTable, "memptr.vtable"); |
| |
| // Apply the offset. |
| llvm::Value *VTableOffset = FnAsInt; |
| if (!IsARM) VTableOffset = Builder.CreateSub(VTableOffset, ptrdiff_1); |
| VTable = Builder.CreateGEP(VTable, VTableOffset); |
| |
| // Load the virtual function to call. |
| VTable = Builder.CreateBitCast(VTable, FTy->getPointerTo()->getPointerTo()); |
| llvm::Value *VirtualFn = Builder.CreateLoad(VTable, "memptr.virtualfn"); |
| CGF.EmitBranch(FnEnd); |
| |
| // In the non-virtual path, the function pointer is actually a |
| // function pointer. |
| CGF.EmitBlock(FnNonVirtual); |
| llvm::Value *NonVirtualFn = |
| Builder.CreateIntToPtr(FnAsInt, FTy->getPointerTo(), "memptr.nonvirtualfn"); |
| |
| // We're done. |
| CGF.EmitBlock(FnEnd); |
| llvm::PHINode *Callee = Builder.CreatePHI(FTy->getPointerTo(), 2); |
| Callee->addIncoming(VirtualFn, FnVirtual); |
| Callee->addIncoming(NonVirtualFn, FnNonVirtual); |
| return Callee; |
| } |
| |
| /// Compute an l-value by applying the given pointer-to-member to a |
| /// base object. |
| llvm::Value *ItaniumCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF, |
| llvm::Value *Base, |
| llvm::Value *MemPtr, |
| const MemberPointerType *MPT) { |
| assert(MemPtr->getType() == getPtrDiffTy()); |
| |
| CGBuilderTy &Builder = CGF.Builder; |
| |
| unsigned AS = cast<llvm::PointerType>(Base->getType())->getAddressSpace(); |
| |
| // Cast to char*. |
| Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS)); |
| |
| // Apply the offset, which we assume is non-null. |
| llvm::Value *Addr = Builder.CreateInBoundsGEP(Base, MemPtr, "memptr.offset"); |
| |
| // Cast the address to the appropriate pointer type, adopting the |
| // address space of the base pointer. |
| llvm::Type *PType |
| = CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS); |
| return Builder.CreateBitCast(Addr, PType); |
| } |
| |
| /// Perform a derived-to-base or base-to-derived member pointer conversion. |
| /// |
| /// Obligatory offset/adjustment diagram: |
| /// <-- offset --> <-- adjustment --> |
| /// |--------------------------|----------------------|--------------------| |
| /// ^Derived address point ^Base address point ^Member address point |
| /// |
| /// So when converting a base member pointer to a derived member pointer, |
| /// we add the offset to the adjustment because the address point has |
| /// decreased; and conversely, when converting a derived MP to a base MP |
| /// we subtract the offset from the adjustment because the address point |
| /// has increased. |
| /// |
| /// The standard forbids (at compile time) conversion to and from |
| /// virtual bases, which is why we don't have to consider them here. |
| /// |
| /// The standard forbids (at run time) casting a derived MP to a base |
| /// MP when the derived MP does not point to a member of the base. |
| /// This is why -1 is a reasonable choice for null data member |
| /// pointers. |
| llvm::Value * |
| ItaniumCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, |
| const CastExpr *E, |
| llvm::Value *Src) { |
| assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || |
| E->getCastKind() == CK_BaseToDerivedMemberPointer); |
| |
| if (isa<llvm::Constant>(Src)) |
| return EmitMemberPointerConversion(cast<llvm::Constant>(Src), E); |
| |
| CGBuilderTy &Builder = CGF.Builder; |
| |
| const MemberPointerType *SrcTy = |
| E->getSubExpr()->getType()->getAs<MemberPointerType>(); |
| const MemberPointerType *DestTy = E->getType()->getAs<MemberPointerType>(); |
| |
| const CXXRecordDecl *SrcDecl = SrcTy->getClass()->getAsCXXRecordDecl(); |
| const CXXRecordDecl *DestDecl = DestTy->getClass()->getAsCXXRecordDecl(); |
| |
| bool DerivedToBase = |
| E->getCastKind() == CK_DerivedToBaseMemberPointer; |
| |
| const CXXRecordDecl *DerivedDecl; |
| if (DerivedToBase) |
| DerivedDecl = SrcDecl; |
| else |
| DerivedDecl = DestDecl; |
| |
| llvm::Constant *Adj = |
| CGF.CGM.GetNonVirtualBaseClassOffset(DerivedDecl, |
| E->path_begin(), |
| E->path_end()); |
| if (!Adj) return Src; |
| |
| // For member data pointers, this is just a matter of adding the |
| // offset if the source is non-null. |
| if (SrcTy->isMemberDataPointer()) { |
| llvm::Value *Dst; |
| if (DerivedToBase) |
| Dst = Builder.CreateNSWSub(Src, Adj, "adj"); |
| else |
| Dst = Builder.CreateNSWAdd(Src, Adj, "adj"); |
| |
| // Null check. |
| llvm::Value *Null = llvm::Constant::getAllOnesValue(Src->getType()); |
| llvm::Value *IsNull = Builder.CreateICmpEQ(Src, Null, "memptr.isnull"); |
| return Builder.CreateSelect(IsNull, Src, Dst); |
| } |
| |
| // The this-adjustment is left-shifted by 1 on ARM. |
| if (IsARM) { |
| uint64_t Offset = cast<llvm::ConstantInt>(Adj)->getZExtValue(); |
| Offset <<= 1; |
| Adj = llvm::ConstantInt::get(Adj->getType(), Offset); |
| } |
| |
| llvm::Value *SrcAdj = Builder.CreateExtractValue(Src, 1, "src.adj"); |
| llvm::Value *DstAdj; |
| if (DerivedToBase) |
| DstAdj = Builder.CreateNSWSub(SrcAdj, Adj, "adj"); |
| else |
| DstAdj = Builder.CreateNSWAdd(SrcAdj, Adj, "adj"); |
| |
| return Builder.CreateInsertValue(Src, DstAdj, 1); |
| } |
| |
| llvm::Constant * |
| ItaniumCXXABI::EmitMemberPointerConversion(llvm::Constant *C, |
| const CastExpr *E) { |
| const MemberPointerType *SrcTy = |
| E->getSubExpr()->getType()->getAs<MemberPointerType>(); |
| const MemberPointerType *DestTy = |
| E->getType()->getAs<MemberPointerType>(); |
| |
| bool DerivedToBase = |
| E->getCastKind() == CK_DerivedToBaseMemberPointer; |
| |
| const CXXRecordDecl *DerivedDecl; |
| if (DerivedToBase) |
| DerivedDecl = SrcTy->getClass()->getAsCXXRecordDecl(); |
| else |
| DerivedDecl = DestTy->getClass()->getAsCXXRecordDecl(); |
| |
| // Calculate the offset to the base class. |
| llvm::Constant *Offset = |
| CGM.GetNonVirtualBaseClassOffset(DerivedDecl, |
| E->path_begin(), |
| E->path_end()); |
| // If there's no offset, we're done. |
| if (!Offset) return C; |
| |
| // If the source is a member data pointer, we have to do a null |
| // check and then add the offset. In the common case, we can fold |
| // away the offset. |
| if (SrcTy->isMemberDataPointer()) { |
| assert(C->getType() == getPtrDiffTy()); |
| |
| // If it's a constant int, just create a new constant int. |
| if (llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C)) { |
| int64_t Src = CI->getSExtValue(); |
| |
| // Null converts to null. |
| if (Src == -1) return CI; |
| |
| // Otherwise, just add the offset. |
| int64_t OffsetV = cast<llvm::ConstantInt>(Offset)->getSExtValue(); |
| int64_t Dst = (DerivedToBase ? Src - OffsetV : Src + OffsetV); |
| return llvm::ConstantInt::get(CI->getType(), Dst, /*signed*/ true); |
| } |
| |
| // Otherwise, we have to form a constant select expression. |
| llvm::Constant *Null = llvm::Constant::getAllOnesValue(C->getType()); |
| |
| llvm::Constant *IsNull = |
| llvm::ConstantExpr::getICmp(llvm::ICmpInst::ICMP_EQ, C, Null); |
| |
| llvm::Constant *Dst; |
| if (DerivedToBase) |
| Dst = llvm::ConstantExpr::getNSWSub(C, Offset); |
| else |
| Dst = llvm::ConstantExpr::getNSWAdd(C, Offset); |
| |
| return llvm::ConstantExpr::getSelect(IsNull, Null, Dst); |
| } |
| |
| // The this-adjustment is left-shifted by 1 on ARM. |
| if (IsARM) { |
| int64_t OffsetV = cast<llvm::ConstantInt>(Offset)->getSExtValue(); |
| OffsetV <<= 1; |
| Offset = llvm::ConstantInt::get(Offset->getType(), OffsetV); |
| } |
| |
| llvm::ConstantStruct *CS = cast<llvm::ConstantStruct>(C); |
| |
| llvm::Constant *Values[2] = { CS->getOperand(0), 0 }; |
| if (DerivedToBase) |
| Values[1] = llvm::ConstantExpr::getSub(CS->getOperand(1), Offset); |
| else |
| Values[1] = llvm::ConstantExpr::getAdd(CS->getOperand(1), Offset); |
| |
| return llvm::ConstantStruct::get(CS->getType(), Values); |
| } |
| |
| |
| llvm::Constant * |
| ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { |
| llvm::Type *ptrdiff_t = getPtrDiffTy(); |
| |
| // Itanium C++ ABI 2.3: |
| // A NULL pointer is represented as -1. |
| if (MPT->isMemberDataPointer()) |
| return llvm::ConstantInt::get(ptrdiff_t, -1ULL, /*isSigned=*/true); |
| |
| llvm::Constant *Zero = llvm::ConstantInt::get(ptrdiff_t, 0); |
| llvm::Constant *Values[2] = { Zero, Zero }; |
| return llvm::ConstantStruct::getAnon(Values); |
| } |
| |
| llvm::Constant * |
| ItaniumCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, |
| CharUnits offset) { |
| // Itanium C++ ABI 2.3: |
| // A pointer to data member is an offset from the base address of |
| // the class object containing it, represented as a ptrdiff_t |
| return llvm::ConstantInt::get(getPtrDiffTy(), offset.getQuantity()); |
| } |
| |
| llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) { |
| return BuildMemberPointer(MD, CharUnits::Zero()); |
| } |
| |
| llvm::Constant *ItaniumCXXABI::BuildMemberPointer(const CXXMethodDecl *MD, |
| CharUnits ThisAdjustment) { |
| assert(MD->isInstance() && "Member function must not be static!"); |
| MD = MD->getCanonicalDecl(); |
| |
| CodeGenTypes &Types = CGM.getTypes(); |
| llvm::Type *ptrdiff_t = getPtrDiffTy(); |
| |
| // Get the function pointer (or index if this is a virtual function). |
| llvm::Constant *MemPtr[2]; |
| if (MD->isVirtual()) { |
| uint64_t Index = CGM.getVTableContext().getMethodVTableIndex(MD); |
| |
| const ASTContext &Context = getContext(); |
| CharUnits PointerWidth = |
| Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); |
| uint64_t VTableOffset = (Index * PointerWidth.getQuantity()); |
| |
| if (IsARM) { |
| // ARM C++ ABI 3.2.1: |
| // This ABI specifies that adj contains twice the this |
| // adjustment, plus 1 if the member function is virtual. The |
| // least significant bit of adj then makes exactly the same |
| // discrimination as the least significant bit of ptr does for |
| // Itanium. |
| MemPtr[0] = llvm::ConstantInt::get(ptrdiff_t, VTableOffset); |
| MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, |
| 2 * ThisAdjustment.getQuantity() + 1); |
| } else { |
| // Itanium C++ ABI 2.3: |
| // For a virtual function, [the pointer field] is 1 plus the |
| // virtual table offset (in bytes) of the function, |
| // represented as a ptrdiff_t. |
| MemPtr[0] = llvm::ConstantInt::get(ptrdiff_t, VTableOffset + 1); |
| MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, |
| ThisAdjustment.getQuantity()); |
| } |
| } else { |
| const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); |
| llvm::Type *Ty; |
| // Check whether the function has a computable LLVM signature. |
| if (Types.isFuncTypeConvertible(FPT)) { |
| // The function has a computable LLVM signature; use the correct type. |
| Ty = Types.GetFunctionType(Types.getFunctionInfo(MD), |
| FPT->isVariadic()); |
| } else { |
| // Use an arbitrary non-function type to tell GetAddrOfFunction that the |
| // function type is incomplete. |
| Ty = ptrdiff_t; |
| } |
| llvm::Constant *addr = CGM.GetAddrOfFunction(MD, Ty); |
| |
| MemPtr[0] = llvm::ConstantExpr::getPtrToInt(addr, ptrdiff_t); |
| MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, (IsARM ? 2 : 1) * |
| ThisAdjustment.getQuantity()); |
| } |
| |
| return llvm::ConstantStruct::getAnon(MemPtr); |
| } |
| |
| llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const APValue &MP, |
| QualType MPType) { |
| const MemberPointerType *MPT = MPType->castAs<MemberPointerType>(); |
| const ValueDecl *MPD = MP.getMemberPointerDecl(); |
| if (!MPD) |
| return EmitNullMemberPointer(MPT); |
| |
| // Compute the this-adjustment. |
| CharUnits ThisAdjustment = CharUnits::Zero(); |
| ArrayRef<const CXXRecordDecl*> Path = MP.getMemberPointerPath(); |
| bool DerivedMember = MP.isMemberPointerToDerivedMember(); |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(MPD->getDeclContext()); |
| for (unsigned I = 0, N = Path.size(); I != N; ++I) { |
| const CXXRecordDecl *Base = RD; |
| const CXXRecordDecl *Derived = Path[I]; |
| if (DerivedMember) |
| std::swap(Base, Derived); |
| ThisAdjustment += |
| getContext().getASTRecordLayout(Derived).getBaseClassOffset(Base); |
| RD = Path[I]; |
| } |
| if (DerivedMember) |
| ThisAdjustment = -ThisAdjustment; |
| |
| if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) |
| return BuildMemberPointer(MD, ThisAdjustment); |
| |
| CharUnits FieldOffset = |
| getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD)); |
| return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset); |
| } |
| |
| /// The comparison algorithm is pretty easy: the member pointers are |
| /// the same if they're either bitwise identical *or* both null. |
| /// |
| /// ARM is different here only because null-ness is more complicated. |
| llvm::Value * |
| ItaniumCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF, |
| llvm::Value *L, |
| llvm::Value *R, |
| const MemberPointerType *MPT, |
| bool Inequality) { |
| CGBuilderTy &Builder = CGF.Builder; |
| |
| llvm::ICmpInst::Predicate Eq; |
| llvm::Instruction::BinaryOps And, Or; |
| if (Inequality) { |
| Eq = llvm::ICmpInst::ICMP_NE; |
| And = llvm::Instruction::Or; |
| Or = llvm::Instruction::And; |
| } else { |
| Eq = llvm::ICmpInst::ICMP_EQ; |
| And = llvm::Instruction::And; |
| Or = llvm::Instruction::Or; |
| } |
| |
| // Member data pointers are easy because there's a unique null |
| // value, so it just comes down to bitwise equality. |
| if (MPT->isMemberDataPointer()) |
| return Builder.CreateICmp(Eq, L, R); |
| |
| // For member function pointers, the tautologies are more complex. |
| // The Itanium tautology is: |
| // (L == R) <==> (L.ptr == R.ptr && (L.ptr == 0 || L.adj == R.adj)) |
| // The ARM tautology is: |
| // (L == R) <==> (L.ptr == R.ptr && |
| // (L.adj == R.adj || |
| // (L.ptr == 0 && ((L.adj|R.adj) & 1) == 0))) |
| // The inequality tautologies have exactly the same structure, except |
| // applying De Morgan's laws. |
| |
| llvm::Value *LPtr = Builder.CreateExtractValue(L, 0, "lhs.memptr.ptr"); |
| llvm::Value *RPtr = Builder.CreateExtractValue(R, 0, "rhs.memptr.ptr"); |
| |
| // This condition tests whether L.ptr == R.ptr. This must always be |
| // true for equality to hold. |
| llvm::Value *PtrEq = Builder.CreateICmp(Eq, LPtr, RPtr, "cmp.ptr"); |
| |
| // This condition, together with the assumption that L.ptr == R.ptr, |
| // tests whether the pointers are both null. ARM imposes an extra |
| // condition. |
| llvm::Value *Zero = llvm::Constant::getNullValue(LPtr->getType()); |
| llvm::Value *EqZero = Builder.CreateICmp(Eq, LPtr, Zero, "cmp.ptr.null"); |
| |
| // This condition tests whether L.adj == R.adj. If this isn't |
| // true, the pointers are unequal unless they're both null. |
| llvm::Value *LAdj = Builder.CreateExtractValue(L, 1, "lhs.memptr.adj"); |
| llvm::Value *RAdj = Builder.CreateExtractValue(R, 1, "rhs.memptr.adj"); |
| llvm::Value *AdjEq = Builder.CreateICmp(Eq, LAdj, RAdj, "cmp.adj"); |
| |
| // Null member function pointers on ARM clear the low bit of Adj, |
| // so the zero condition has to check that neither low bit is set. |
| if (IsARM) { |
| llvm::Value *One = llvm::ConstantInt::get(LPtr->getType(), 1); |
| |
| // Compute (l.adj | r.adj) & 1 and test it against zero. |
| llvm::Value *OrAdj = Builder.CreateOr(LAdj, RAdj, "or.adj"); |
| llvm::Value *OrAdjAnd1 = Builder.CreateAnd(OrAdj, One); |
| llvm::Value *OrAdjAnd1EqZero = Builder.CreateICmp(Eq, OrAdjAnd1, Zero, |
| "cmp.or.adj"); |
| EqZero = Builder.CreateBinOp(And, EqZero, OrAdjAnd1EqZero); |
| } |
| |
| // Tie together all our conditions. |
| llvm::Value *Result = Builder.CreateBinOp(Or, EqZero, AdjEq); |
| Result = Builder.CreateBinOp(And, PtrEq, Result, |
| Inequality ? "memptr.ne" : "memptr.eq"); |
| return Result; |
| } |
| |
| llvm::Value * |
| ItaniumCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF, |
| llvm::Value *MemPtr, |
| const MemberPointerType *MPT) { |
| CGBuilderTy &Builder = CGF.Builder; |
| |
| /// For member data pointers, this is just a check against -1. |
| if (MPT->isMemberDataPointer()) { |
| assert(MemPtr->getType() == getPtrDiffTy()); |
| llvm::Value *NegativeOne = |
| llvm::Constant::getAllOnesValue(MemPtr->getType()); |
| return Builder.CreateICmpNE(MemPtr, NegativeOne, "memptr.tobool"); |
| } |
| |
| // In Itanium, a member function pointer is not null if 'ptr' is not null. |
| llvm::Value *Ptr = Builder.CreateExtractValue(MemPtr, 0, "memptr.ptr"); |
| |
| llvm::Constant *Zero = llvm::ConstantInt::get(Ptr->getType(), 0); |
| llvm::Value *Result = Builder.CreateICmpNE(Ptr, Zero, "memptr.tobool"); |
| |
| // On ARM, a member function pointer is also non-null if the low bit of 'adj' |
| // (the virtual bit) is set. |
| if (IsARM) { |
| llvm::Constant *One = llvm::ConstantInt::get(Ptr->getType(), 1); |
| llvm::Value *Adj = Builder.CreateExtractValue(MemPtr, 1, "memptr.adj"); |
| llvm::Value *VirtualBit = Builder.CreateAnd(Adj, One, "memptr.virtualbit"); |
| llvm::Value *IsVirtual = Builder.CreateICmpNE(VirtualBit, Zero, |
| "memptr.isvirtual"); |
| Result = Builder.CreateOr(Result, IsVirtual); |
| } |
| |
| return Result; |
| } |
| |
| /// The Itanium ABI requires non-zero initialization only for data |
| /// member pointers, for which '0' is a valid offset. |
| bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) { |
| return MPT->getPointeeType()->isFunctionType(); |
| } |
| |
| /// The generic ABI passes 'this', plus a VTT if it's initializing a |
| /// base subobject. |
| void ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor, |
| CXXCtorType Type, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys) { |
| ASTContext &Context = getContext(); |
| |
| // 'this' is already there. |
| |
| // Check if we need to add a VTT parameter (which has type void **). |
| if (Type == Ctor_Base && Ctor->getParent()->getNumVBases() != 0) |
| ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy)); |
| } |
| |
| /// The ARM ABI does the same as the Itanium ABI, but returns 'this'. |
| void ARMCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor, |
| CXXCtorType Type, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys) { |
| ItaniumCXXABI::BuildConstructorSignature(Ctor, Type, ResTy, ArgTys); |
| ResTy = ArgTys[0]; |
| } |
| |
| /// The generic ABI passes 'this', plus a VTT if it's destroying a |
| /// base subobject. |
| void ItaniumCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor, |
| CXXDtorType Type, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys) { |
| ASTContext &Context = getContext(); |
| |
| // 'this' is already there. |
| |
| // Check if we need to add a VTT parameter (which has type void **). |
| if (Type == Dtor_Base && Dtor->getParent()->getNumVBases() != 0) |
| ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy)); |
| } |
| |
| /// The ARM ABI does the same as the Itanium ABI, but returns 'this' |
| /// for non-deleting destructors. |
| void ARMCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor, |
| CXXDtorType Type, |
| CanQualType &ResTy, |
| SmallVectorImpl<CanQualType> &ArgTys) { |
| ItaniumCXXABI::BuildDestructorSignature(Dtor, Type, ResTy, ArgTys); |
| |
| if (Type != Dtor_Deleting) |
| ResTy = ArgTys[0]; |
| } |
| |
| void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF, |
| QualType &ResTy, |
| FunctionArgList &Params) { |
| /// Create the 'this' variable. |
| BuildThisParam(CGF, Params); |
| |
| const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); |
| assert(MD->isInstance()); |
| |
| // Check if we need a VTT parameter as well. |
| if (CodeGenVTables::needsVTTParameter(CGF.CurGD)) { |
| ASTContext &Context = getContext(); |
| |
| // FIXME: avoid the fake decl |
| QualType T = Context.getPointerType(Context.VoidPtrTy); |
| ImplicitParamDecl *VTTDecl |
| = ImplicitParamDecl::Create(Context, 0, MD->getLocation(), |
| &Context.Idents.get("vtt"), T); |
| Params.push_back(VTTDecl); |
| getVTTDecl(CGF) = VTTDecl; |
| } |
| } |
| |
| void ARMCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF, |
| QualType &ResTy, |
| FunctionArgList &Params) { |
| ItaniumCXXABI::BuildInstanceFunctionParams(CGF, ResTy, Params); |
| |
| // Return 'this' from certain constructors and destructors. |
| if (HasThisReturn(CGF.CurGD)) |
| ResTy = Params[0]->getType(); |
| } |
| |
| void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { |
| /// Initialize the 'this' slot. |
| EmitThisParam(CGF); |
| |
| /// Initialize the 'vtt' slot if needed. |
| if (getVTTDecl(CGF)) { |
| getVTTValue(CGF) |
| = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getVTTDecl(CGF)), |
| "vtt"); |
| } |
| } |
| |
| void ARMCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { |
| ItaniumCXXABI::EmitInstanceFunctionProlog(CGF); |
| |
| /// Initialize the return slot to 'this' at the start of the |
| /// function. |
| if (HasThisReturn(CGF.CurGD)) |
| CGF.Builder.CreateStore(CGF.LoadCXXThis(), CGF.ReturnValue); |
| } |
| |
| void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF, |
| RValue RV, QualType ResultType) { |
| if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl())) |
| return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType); |
| |
| // Destructor thunks in the ARM ABI have indeterminate results. |
| llvm::Type *T = |
| cast<llvm::PointerType>(CGF.ReturnValue->getType())->getElementType(); |
| RValue Undef = RValue::get(llvm::UndefValue::get(T)); |
| return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType); |
| } |
| |
| /************************** Array allocation cookies **************************/ |
| |
| bool ItaniumCXXABI::NeedsArrayCookie(const CXXNewExpr *expr) { |
| // If the class's usual deallocation function takes two arguments, |
| // it needs a cookie. |
| if (expr->doesUsualArrayDeleteWantSize()) |
| return true; |
| |
| // Automatic Reference Counting: |
| // We need an array cookie for pointers with strong or weak lifetime. |
| QualType AllocatedType = expr->getAllocatedType(); |
| if (getContext().getLangOptions().ObjCAutoRefCount && |
| AllocatedType->isObjCLifetimeType()) { |
| switch (AllocatedType.getObjCLifetime()) { |
| case Qualifiers::OCL_None: |
| case Qualifiers::OCL_ExplicitNone: |
| case Qualifiers::OCL_Autoreleasing: |
| return false; |
| |
| case Qualifiers::OCL_Strong: |
| case Qualifiers::OCL_Weak: |
| return true; |
| } |
| } |
| |
| // Otherwise, if the class has a non-trivial destructor, it always |
| // needs a cookie. |
| const CXXRecordDecl *record = |
| AllocatedType->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); |
| return (record && !record->hasTrivialDestructor()); |
| } |
| |
| bool ItaniumCXXABI::NeedsArrayCookie(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(); |
| } |
| |
| CharUnits ItaniumCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) { |
| if (!NeedsArrayCookie(expr)) |
| return CharUnits::Zero(); |
| |
| // Padding is the maximum of sizeof(size_t) and alignof(elementType) |
| ASTContext &Ctx = getContext(); |
| return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()), |
| Ctx.getTypeAlignInChars(expr->getAllocatedType())); |
| } |
| |
| llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *NewPtr, |
| llvm::Value *NumElements, |
| const CXXNewExpr *expr, |
| QualType ElementType) { |
| assert(NeedsArrayCookie(expr)); |
| |
| unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace(); |
| |
| ASTContext &Ctx = getContext(); |
| QualType SizeTy = Ctx.getSizeType(); |
| CharUnits SizeSize = Ctx.getTypeSizeInChars(SizeTy); |
| |
| // The size of the cookie. |
| CharUnits CookieSize = |
| std::max(SizeSize, Ctx.getTypeAlignInChars(ElementType)); |
| |
| // Compute an offset to the cookie. |
| llvm::Value *CookiePtr = NewPtr; |
| CharUnits CookieOffset = CookieSize - SizeSize; |
| if (!CookieOffset.isZero()) |
| CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_64(CookiePtr, |
| CookieOffset.getQuantity()); |
| |
| // Write the number of elements into the appropriate slot. |
| llvm::Value *NumElementsPtr |
| = CGF.Builder.CreateBitCast(CookiePtr, |
| CGF.ConvertType(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 ItaniumCXXABI::ReadArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *Ptr, |
| const CXXDeleteExpr *expr, |
| QualType ElementType, |
| llvm::Value *&NumElements, |
| llvm::Value *&AllocPtr, |
| CharUnits &CookieSize) { |
| // Derive a char* in the same address space as the pointer. |
| unsigned AS = cast<llvm::PointerType>(Ptr->getType())->getAddressSpace(); |
| llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS); |
| |
| // If we don't need an array cookie, bail out early. |
| if (!NeedsArrayCookie(expr, ElementType)) { |
| AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy); |
| NumElements = 0; |
| CookieSize = CharUnits::Zero(); |
| return; |
| } |
| |
| QualType SizeTy = getContext().getSizeType(); |
| CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy); |
| llvm::Type *SizeLTy = CGF.ConvertType(SizeTy); |
| |
| CookieSize |
| = std::max(SizeSize, getContext().getTypeAlignInChars(ElementType)); |
| |
| CharUnits NumElementsOffset = CookieSize - SizeSize; |
| |
| // Compute the allocated pointer. |
| AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy); |
| AllocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr, |
| -CookieSize.getQuantity()); |
| |
| llvm::Value *NumElementsPtr = AllocPtr; |
| if (!NumElementsOffset.isZero()) |
| NumElementsPtr = |
| CGF.Builder.CreateConstInBoundsGEP1_64(NumElementsPtr, |
| NumElementsOffset.getQuantity()); |
| NumElementsPtr = |
| CGF.Builder.CreateBitCast(NumElementsPtr, SizeLTy->getPointerTo(AS)); |
| NumElements = CGF.Builder.CreateLoad(NumElementsPtr); |
| } |
| |
| CharUnits ARMCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) { |
| if (!NeedsArrayCookie(expr)) |
| return CharUnits::Zero(); |
| |
| // On ARM, the cookie is always: |
| // struct array_cookie { |
| // std::size_t element_size; // element_size != 0 |
| // std::size_t element_count; |
| // }; |
| // TODO: what should we do if the allocated type actually wants |
| // greater alignment? |
| return getContext().getTypeSizeInChars(getContext().getSizeType()) * 2; |
| } |
| |
| llvm::Value *ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *NewPtr, |
| llvm::Value *NumElements, |
| const CXXNewExpr *expr, |
| QualType ElementType) { |
| assert(NeedsArrayCookie(expr)); |
| |
| // NewPtr is a char*. |
| |
| unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace(); |
| |
| ASTContext &Ctx = getContext(); |
| CharUnits SizeSize = Ctx.getTypeSizeInChars(Ctx.getSizeType()); |
| llvm::IntegerType *SizeTy = |
| cast<llvm::IntegerType>(CGF.ConvertType(Ctx.getSizeType())); |
| |
| // The cookie is always at the start of the buffer. |
| llvm::Value *CookiePtr = NewPtr; |
| |
| // The first element is the element size. |
| CookiePtr = CGF.Builder.CreateBitCast(CookiePtr, SizeTy->getPointerTo(AS)); |
| llvm::Value *ElementSize = llvm::ConstantInt::get(SizeTy, |
| Ctx.getTypeSizeInChars(ElementType).getQuantity()); |
| CGF.Builder.CreateStore(ElementSize, CookiePtr); |
| |
| // The second element is the element count. |
| CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_32(CookiePtr, 1); |
| CGF.Builder.CreateStore(NumElements, CookiePtr); |
| |
| // Finally, compute a pointer to the actual data buffer by skipping |
| // over the cookie completely. |
| CharUnits CookieSize = 2 * SizeSize; |
| return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr, |
| CookieSize.getQuantity()); |
| } |
| |
| void ARMCXXABI::ReadArrayCookie(CodeGenFunction &CGF, |
| llvm::Value *Ptr, |
| const CXXDeleteExpr *expr, |
| QualType ElementType, |
| llvm::Value *&NumElements, |
| llvm::Value *&AllocPtr, |
| CharUnits &CookieSize) { |
| // Derive a char* in the same address space as the pointer. |
| unsigned AS = cast<llvm::PointerType>(Ptr->getType())->getAddressSpace(); |
| llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS); |
| |
| // If we don't need an array cookie, bail out early. |
| if (!NeedsArrayCookie(expr, ElementType)) { |
| AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy); |
| NumElements = 0; |
| CookieSize = CharUnits::Zero(); |
| return; |
| } |
| |
| QualType SizeTy = getContext().getSizeType(); |
| CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy); |
| llvm::Type *SizeLTy = CGF.ConvertType(SizeTy); |
| |
| // The cookie size is always 2 * sizeof(size_t). |
| CookieSize = 2 * SizeSize; |
| |
| // The allocated pointer is the input ptr, minus that amount. |
| AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy); |
| AllocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr, |
| -CookieSize.getQuantity()); |
| |
| // The number of elements is at offset sizeof(size_t) relative to that. |
| llvm::Value *NumElementsPtr |
| = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr, |
| SizeSize.getQuantity()); |
| NumElementsPtr = |
| CGF.Builder.CreateBitCast(NumElementsPtr, SizeLTy->getPointerTo(AS)); |
| NumElements = CGF.Builder.CreateLoad(NumElementsPtr); |
| } |
| |
| /*********************** Static local initialization **************************/ |
| |
| static llvm::Constant *getGuardAcquireFn(CodeGenModule &CGM, |
| llvm::PointerType *GuardPtrTy) { |
| // int __cxa_guard_acquire(__guard *guard_object); |
| llvm::FunctionType *FTy = |
| llvm::FunctionType::get(CGM.getTypes().ConvertType(CGM.getContext().IntTy), |
| GuardPtrTy, /*isVarArg=*/false); |
| |
| return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire"); |
| } |
| |
| static llvm::Constant *getGuardReleaseFn(CodeGenModule &CGM, |
| llvm::PointerType *GuardPtrTy) { |
| // void __cxa_guard_release(__guard *guard_object); |
| llvm::FunctionType *FTy = |
| llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), |
| GuardPtrTy, /*isVarArg=*/false); |
| |
| return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release"); |
| } |
| |
| static llvm::Constant *getGuardAbortFn(CodeGenModule &CGM, |
| llvm::PointerType *GuardPtrTy) { |
| // void __cxa_guard_abort(__guard *guard_object); |
| llvm::FunctionType *FTy = |
| llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), |
| GuardPtrTy, /*isVarArg=*/false); |
| |
| return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort"); |
| } |
| |
| namespace { |
| struct CallGuardAbort : EHScopeStack::Cleanup { |
| llvm::GlobalVariable *Guard; |
| CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {} |
| |
| void Emit(CodeGenFunction &CGF, Flags flags) { |
| CGF.Builder.CreateCall(getGuardAbortFn(CGF.CGM, Guard->getType()), Guard) |
| ->setDoesNotThrow(); |
| } |
| }; |
| } |
| |
| /// The ARM code here follows the Itanium code closely enough that we |
| /// just special-case it at particular places. |
| void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF, |
| const VarDecl &D, |
| llvm::GlobalVariable *GV) { |
| CGBuilderTy &Builder = CGF.Builder; |
| |
| // We only need to use thread-safe statics for local variables; |
| // global initialization is always single-threaded. |
| bool threadsafe = |
| (getContext().getLangOptions().ThreadsafeStatics && D.isLocalVarDecl()); |
| |
| llvm::IntegerType *GuardTy; |
| |
| // If we have a global variable with internal linkage and thread-safe statics |
| // are disabled, we can just let the guard variable be of type i8. |
| bool useInt8GuardVariable = !threadsafe && GV->hasInternalLinkage(); |
| if (useInt8GuardVariable) { |
| GuardTy = CGF.Int8Ty; |
| } else { |
| // Guard variables are 64 bits in the generic ABI and 32 bits on ARM. |
| GuardTy = (IsARM ? CGF.Int32Ty : CGF.Int64Ty); |
| } |
| llvm::PointerType *GuardPtrTy = GuardTy->getPointerTo(); |
| |
| // Create the guard variable. |
| llvm::SmallString<256> GuardVName; |
| llvm::raw_svector_ostream Out(GuardVName); |
| getMangleContext().mangleItaniumGuardVariable(&D, Out); |
| Out.flush(); |
| |
| // Just absorb linkage and visibility from the variable. |
| llvm::GlobalVariable *GuardVariable = |
| new llvm::GlobalVariable(CGM.getModule(), GuardTy, |
| false, GV->getLinkage(), |
| llvm::ConstantInt::get(GuardTy, 0), |
| GuardVName.str()); |
| GuardVariable->setVisibility(GV->getVisibility()); |
| |
| // Test whether the variable has completed initialization. |
| llvm::Value *IsInitialized; |
| |
| // ARM C++ ABI 3.2.3.1: |
| // To support the potential use of initialization guard variables |
| // as semaphores that are the target of ARM SWP and LDREX/STREX |
| // synchronizing instructions we define a static initialization |
| // guard variable to be a 4-byte aligned, 4- byte word with the |
| // following inline access protocol. |
| // #define INITIALIZED 1 |
| // if ((obj_guard & INITIALIZED) != INITIALIZED) { |
| // if (__cxa_guard_acquire(&obj_guard)) |
| // ... |
| // } |
| if (IsARM && !useInt8GuardVariable) { |
| llvm::Value *V = Builder.CreateLoad(GuardVariable); |
| V = Builder.CreateAnd(V, Builder.getInt32(1)); |
| IsInitialized = Builder.CreateIsNull(V, "guard.uninitialized"); |
| |
| // Itanium C++ ABI 3.3.2: |
| // The following is pseudo-code showing how these functions can be used: |
| // if (obj_guard.first_byte == 0) { |
| // if ( __cxa_guard_acquire (&obj_guard) ) { |
| // try { |
| // ... initialize the object ...; |
| // } catch (...) { |
| // __cxa_guard_abort (&obj_guard); |
| // throw; |
| // } |
| // ... queue object destructor with __cxa_atexit() ...; |
| // __cxa_guard_release (&obj_guard); |
| // } |
| // } |
| } else { |
| // Load the first byte of the guard variable. |
| llvm::Type *PtrTy = Builder.getInt8PtrTy(); |
| llvm::LoadInst *LI = |
| Builder.CreateLoad(Builder.CreateBitCast(GuardVariable, PtrTy)); |
| LI->setAlignment(1); |
| |
| // Itanium ABI: |
| // An implementation supporting thread-safety on multiprocessor |
| // systems must also guarantee that references to the initialized |
| // object do not occur before the load of the initialization flag. |
| // |
| // In LLVM, we do this by marking the load Acquire. |
| if (threadsafe) |
| LI->setAtomic(llvm::Acquire); |
| |
| IsInitialized = Builder.CreateIsNull(LI, "guard.uninitialized"); |
| } |
| |
| llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check"); |
| llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end"); |
| |
| // Check if the first byte of the guard variable is zero. |
| Builder.CreateCondBr(IsInitialized, InitCheckBlock, EndBlock); |
| |
| CGF.EmitBlock(InitCheckBlock); |
| |
| // Variables used when coping with thread-safe statics and exceptions. |
| if (threadsafe) { |
| // Call __cxa_guard_acquire. |
| llvm::Value *V |
| = Builder.CreateCall(getGuardAcquireFn(CGM, GuardPtrTy), GuardVariable); |
| |
| llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init"); |
| |
| Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"), |
| InitBlock, EndBlock); |
| |
| // Call __cxa_guard_abort along the exceptional edge. |
| CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, GuardVariable); |
| |
| CGF.EmitBlock(InitBlock); |
| } |
| |
| // Emit the initializer and add a global destructor if appropriate. |
| CGF.EmitCXXGlobalVarDeclInit(D, GV); |
| |
| if (threadsafe) { |
| // Pop the guard-abort cleanup if we pushed one. |
| CGF.PopCleanupBlock(); |
| |
| // Call __cxa_guard_release. This cannot throw. |
| Builder.CreateCall(getGuardReleaseFn(CGM, GuardPtrTy), GuardVariable); |
| } else { |
| Builder.CreateStore(llvm::ConstantInt::get(GuardTy, 1), GuardVariable); |
| } |
| |
| CGF.EmitBlock(EndBlock); |
| } |