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Diffstat (limited to 'lib/CodeGen/ItaniumCXXABI.cpp')
| -rw-r--r-- | lib/CodeGen/ItaniumCXXABI.cpp | 992 |
1 files changed, 988 insertions, 4 deletions
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp index 98db75e..eefc530 100644 --- a/lib/CodeGen/ItaniumCXXABI.cpp +++ b/lib/CodeGen/ItaniumCXXABI.cpp @@ -12,28 +12,1012 @@ // 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 "Mangle.h" +#include <clang/AST/Type.h> +#include <llvm/Target/TargetData.h> +#include <llvm/Value.h> using namespace clang; +using namespace CodeGen; namespace { -class ItaniumCXXABI : public CodeGen::CXXABI { +class ItaniumCXXABI : public CodeGen::CGCXXABI { +private: + const llvm::IntegerType *PtrDiffTy; +protected: CodeGen::MangleContext MangleCtx; + bool IsARM; + + // It's a little silly for us to cache this. + const llvm::IntegerType *getPtrDiffTy() { + if (!PtrDiffTy) { + QualType T = getContext().getPointerDiffType(); + const llvm::Type *Ty = CGM.getTypes().ConvertTypeRecursive(T); + PtrDiffTy = cast<llvm::IntegerType>(Ty); + } + return PtrDiffTy; + } + + bool NeedsArrayCookie(QualType ElementType); + public: - ItaniumCXXABI(CodeGen::CodeGenModule &CGM) : - MangleCtx(CGM.getContext(), CGM.getDiags()) { } + ItaniumCXXABI(CodeGen::CodeGenModule &CGM, bool IsARM = false) : + CGCXXABI(CGM), PtrDiffTy(0), MangleCtx(getContext(), CGM.getDiags()), + IsARM(IsARM) { } CodeGen::MangleContext &getMangleContext() { return MangleCtx; } + + bool isZeroInitializable(const MemberPointerType *MPT); + + const 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 *EmitMemberPointer(const FieldDecl *FD); + + 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, + llvm::SmallVectorImpl<CanQualType> &ArgTys); + + void BuildDestructorSignature(const CXXDestructorDecl *Dtor, + CXXDtorType T, + CanQualType &ResTy, + llvm::SmallVectorImpl<CanQualType> &ArgTys); + + void BuildInstanceFunctionParams(CodeGenFunction &CGF, + QualType &ResTy, + FunctionArgList &Params); + + void EmitInstanceFunctionProlog(CodeGenFunction &CGF); + + CharUnits GetArrayCookieSize(QualType ElementType); + llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, + llvm::Value *NewPtr, + llvm::Value *NumElements, + QualType ElementType); + void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, + QualType ElementType, llvm::Value *&NumElements, + llvm::Value *&AllocPtr, CharUnits &CookieSize); +}; + +class ARMCXXABI : public ItaniumCXXABI { +public: + ARMCXXABI(CodeGen::CodeGenModule &CGM) : ItaniumCXXABI(CGM, /*ARM*/ true) {} + + void BuildConstructorSignature(const CXXConstructorDecl *Ctor, + CXXCtorType T, + CanQualType &ResTy, + llvm::SmallVectorImpl<CanQualType> &ArgTys); + + void BuildDestructorSignature(const CXXDestructorDecl *Dtor, + CXXDtorType T, + CanQualType &ResTy, + llvm::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(QualType ElementType); + llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, + llvm::Value *NewPtr, + llvm::Value *NumElements, + QualType ElementType); + void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr, + 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::CXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) { +CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) { return new ItaniumCXXABI(CGM); } +CodeGen::CGCXXABI *CodeGen::CreateARMCXXABI(CodeGenModule &CGM) { + return new ARMCXXABI(CGM); +} + +const llvm::Type * +ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { + if (MPT->isMemberDataPointer()) + return getPtrDiffTy(); + else + return llvm::StructType::get(CGM.getLLVMContext(), + 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()); + + const llvm::FunctionType *FTy = + CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(RD, FPT), + FPT->isVariadic()); + + const 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. + const 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()); + Callee->reserveOperandSpace(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. + const 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 *BaseDecl, *DerivedDecl; + if (DerivedToBase) + DerivedDecl = SrcDecl, BaseDecl = DestDecl; + else + BaseDecl = SrcDecl, 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(CGM.getLLVMContext(), Values, 2, + /*Packed=*/false); +} + + +llvm::Constant * +ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { + const 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::get(CGM.getLLVMContext(), Values, 2, + /*Packed=*/false); +} + +llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const FieldDecl *FD) { + // 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 + + QualType ClassType = getContext().getTypeDeclType(FD->getParent()); + const llvm::StructType *ClassLTy = + cast<llvm::StructType>(CGM.getTypes().ConvertType(ClassType)); + + const CGRecordLayout &RL = CGM.getTypes().getCGRecordLayout(FD->getParent()); + unsigned FieldNo = RL.getLLVMFieldNo(FD); + uint64_t Offset = + CGM.getTargetData().getStructLayout(ClassLTy)->getElementOffset(FieldNo); + + return llvm::ConstantInt::get(getPtrDiffTy(), Offset); +} + +llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) { + assert(MD->isInstance() && "Member function must not be static!"); + MD = MD->getCanonicalDecl(); + + CodeGenTypes &Types = CGM.getTypes(); + const 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.getVTables().getMethodVTableIndex(MD); + + // FIXME: We shouldn't use / 8 here. + uint64_t PointerWidthInBytes = + getContext().Target.getPointerWidth(0) / 8; + uint64_t VTableOffset = (Index * PointerWidthInBytes); + + 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, 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, 0); + } + } else { + const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); + const llvm::Type *Ty; + // Check whether the function has a computable LLVM signature. + if (!CodeGenTypes::VerifyFuncTypeComplete(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, 0); + } + + return llvm::ConstantStruct::get(CGM.getLLVMContext(), + MemPtr, 2, /*Packed=*/false); +} + +/// 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 null if 'ptr' is 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"); + + // In ARM, it's that, plus the low bit of 'adj' must be zero. + 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 *IsNotVirtual = Builder.CreateICmpEQ(VirtualBit, Zero, + "memptr.notvirtual"); + Result = Builder.CreateAnd(Result, IsNotVirtual); + } + + 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, + llvm::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, + llvm::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, + llvm::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, + llvm::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(std::make_pair(VTTDecl, VTTDecl->getType())); + 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].second; +} + +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. + const 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(QualType ElementType) { + ElementType = getContext().getBaseElementType(ElementType); + const RecordType *RT = ElementType->getAs<RecordType>(); + if (!RT) return false; + + const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); + + // If the class has a non-trivial destructor, it always needs a cookie. + if (!RD->hasTrivialDestructor()) return true; + + // If the class's usual deallocation function takes two arguments, + // it needs a cookie. Otherwise we don't need a cookie. + const CXXMethodDecl *UsualDeallocationFunction = 0; + + // Usual deallocation functions of this form are always found on the + // class. + // + // FIXME: what exactly is this code supposed to do if there's an + // ambiguity? That's possible with using declarations. + DeclarationName OpName = + getContext().DeclarationNames.getCXXOperatorName(OO_Array_Delete); + DeclContext::lookup_const_iterator Op, OpEnd; + for (llvm::tie(Op, OpEnd) = RD->lookup(OpName); Op != OpEnd; ++Op) { + const CXXMethodDecl *Delete = + cast<CXXMethodDecl>((*Op)->getUnderlyingDecl()); + + if (Delete->isUsualDeallocationFunction()) { + UsualDeallocationFunction = Delete; + break; + } + } + + // No usual deallocation function, we don't need a cookie. + if (!UsualDeallocationFunction) + return false; + + // The usual deallocation function doesn't take a size_t argument, + // so we don't need a cookie. + if (UsualDeallocationFunction->getNumParams() == 1) + return false; + + assert(UsualDeallocationFunction->getNumParams() == 2 && + "Unexpected deallocation function type!"); + return true; +} + +CharUnits ItaniumCXXABI::GetArrayCookieSize(QualType ElementType) { + if (!NeedsArrayCookie(ElementType)) + 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(ElementType)); +} + +llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, + llvm::Value *NewPtr, + llvm::Value *NumElements, + QualType ElementType) { + assert(NeedsArrayCookie(ElementType)); + + 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, + 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(); + const llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS); + + // If we don't need an array cookie, bail out early. + if (!NeedsArrayCookie(ElementType)) { + AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy); + NumElements = 0; + CookieSize = CharUnits::Zero(); + return; + } + + QualType SizeTy = getContext().getSizeType(); + CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy); + const 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(QualType ElementType) { + if (!NeedsArrayCookie(ElementType)) + 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, + QualType ElementType) { + assert(NeedsArrayCookie(ElementType)); + + // NewPtr is a char*. + + unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace(); + + ASTContext &Ctx = getContext(); + CharUnits SizeSize = Ctx.getTypeSizeInChars(Ctx.getSizeType()); + const 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, + 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(); + const llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS); + + // If we don't need an array cookie, bail out early. + if (!NeedsArrayCookie(ElementType)) { + AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy); + NumElements = 0; + CookieSize = CharUnits::Zero(); + return; + } + + QualType SizeTy = getContext().getSizeType(); + CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy); + const llvm::Type *SizeLTy = CGF.ConvertType(SizeTy); + + // The cookie size is always 2 * sizeof(size_t). + CookieSize = 2 * SizeSize; + CharUnits NumElementsOffset = CookieSize - 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); +} + |
