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Diffstat (limited to 'clang/lib/CodeGen/ItaniumCXXABI.cpp')
| -rw-r--r-- | clang/lib/CodeGen/ItaniumCXXABI.cpp | 1202 |
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diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp new file mode 100644 index 0000000..98f67f3 --- /dev/null +++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp @@ -0,0 +1,1202 @@ +//===------- 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(const CastExpr *E, + llvm::Constant *Src); + + 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, bool PerformInit); +}; + +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().arrangeCXXMethodType(RD, FPT)); + + 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 bitcast, derived-to-base, or base-to-derived member pointer +/// conversion. +/// +/// Bitcast conversions are always a no-op under Itanium. +/// +/// 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 || + E->getCastKind() == CK_ReinterpretMemberPointer); + + // Under Itanium, reinterprets don't require any additional processing. + if (E->getCastKind() == CK_ReinterpretMemberPointer) return src; + + // Use constant emission if we can. + if (isa<llvm::Constant>(src)) + return EmitMemberPointerConversion(E, cast<llvm::Constant>(src)); + + llvm::Constant *adj = getMemberPointerAdjustment(E); + if (!adj) return src; + + CGBuilderTy &Builder = CGF.Builder; + bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); + + const MemberPointerType *destTy = + E->getType()->castAs<MemberPointerType>(); + + // For member data pointers, this is just a matter of adding the + // offset if the source is non-null. + if (destTy->isMemberDataPointer()) { + llvm::Value *dst; + if (isDerivedToBase) + 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 (isDerivedToBase) + dstAdj = Builder.CreateNSWSub(srcAdj, adj, "adj"); + else + dstAdj = Builder.CreateNSWAdd(srcAdj, adj, "adj"); + + return Builder.CreateInsertValue(src, dstAdj, 1); +} + +llvm::Constant * +ItaniumCXXABI::EmitMemberPointerConversion(const CastExpr *E, + llvm::Constant *src) { + assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || + E->getCastKind() == CK_BaseToDerivedMemberPointer || + E->getCastKind() == CK_ReinterpretMemberPointer); + + // Under Itanium, reinterprets don't require any additional processing. + if (E->getCastKind() == CK_ReinterpretMemberPointer) return src; + + // If the adjustment is trivial, we don't need to do anything. + llvm::Constant *adj = getMemberPointerAdjustment(E); + if (!adj) return src; + + bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); + + const MemberPointerType *destTy = + E->getType()->castAs<MemberPointerType>(); + + // For member data pointers, this is just a matter of adding the + // offset if the source is non-null. + if (destTy->isMemberDataPointer()) { + // null maps to null. + if (src->isAllOnesValue()) return src; + + if (isDerivedToBase) + return llvm::ConstantExpr::getNSWSub(src, adj); + else + return llvm::ConstantExpr::getNSWAdd(src, adj); + } + + // 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::Constant *srcAdj = llvm::ConstantExpr::getExtractValue(src, 1); + llvm::Constant *dstAdj; + if (isDerivedToBase) + dstAdj = llvm::ConstantExpr::getNSWSub(srcAdj, adj); + else + dstAdj = llvm::ConstantExpr::getNSWAdd(srcAdj, adj); + + return llvm::ConstantExpr::getInsertValue(src, dstAdj, 1); +} + +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.arrangeCXXMethodDeclaration(MD)); + } 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(getThisValue(CGF), 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().getLangOpts().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", + llvm::Attribute::NoUnwind); +} + +static llvm::Constant *getGuardReleaseFn(CodeGenModule &CGM, + llvm::PointerType *GuardPtrTy) { + // void __cxa_guard_release(__guard *guard_object); + llvm::FunctionType *FTy = + llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release", + llvm::Attribute::NoUnwind); +} + +static llvm::Constant *getGuardAbortFn(CodeGenModule &CGM, + llvm::PointerType *GuardPtrTy) { + // void __cxa_guard_abort(__guard *guard_object); + llvm::FunctionType *FTy = + llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort", + llvm::Attribute::NoUnwind); +} + +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 *var, + bool shouldPerformInit) { + CGBuilderTy &Builder = CGF.Builder; + + // We only need to use thread-safe statics for local variables; + // global initialization is always single-threaded. + bool threadsafe = + (getContext().getLangOpts().ThreadsafeStatics && D.isLocalVarDecl()); + + // 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 && var->hasInternalLinkage(); + + llvm::IntegerType *guardTy; + 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 if we don't already have it (as we + // might if we're double-emitting this function body). + llvm::GlobalVariable *guard = CGM.getStaticLocalDeclGuardAddress(&D); + if (!guard) { + // Mangle the name for the guard. + SmallString<256> guardName; + { + llvm::raw_svector_ostream out(guardName); + getMangleContext().mangleItaniumGuardVariable(&D, out); + out.flush(); + } + + // Create the guard variable with a zero-initializer. + // Just absorb linkage and visibility from the guarded variable. + guard = new llvm::GlobalVariable(CGM.getModule(), guardTy, + false, var->getLinkage(), + llvm::ConstantInt::get(guardTy, 0), + guardName.str()); + guard->setVisibility(var->getVisibility()); + + CGM.setStaticLocalDeclGuardAddress(&D, guard); + } + + // 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(guard); + 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::LoadInst *LI = + Builder.CreateLoad(Builder.CreateBitCast(guard, CGM.Int8PtrTy)); + 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), guard); + + 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, guard); + + CGF.EmitBlock(InitBlock); + } + + // Emit the initializer and add a global destructor if appropriate. + CGF.EmitCXXGlobalVarDeclInit(D, var, shouldPerformInit); + + 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), guard); + } else { + Builder.CreateStore(llvm::ConstantInt::get(guardTy, 1), guard); + } + + CGF.EmitBlock(EndBlock); +} |