diff --git a/clang/include/clang/AST/Mangle.h b/clang/include/clang/AST/Mangle.h index c5a7ea16a7ec..735ae11a2339 100644 --- a/clang/include/clang/AST/Mangle.h +++ b/clang/include/clang/AST/Mangle.h @@ -204,6 +204,10 @@ public: virtual void mangleVirtualMemPtrThunk(const CXXMethodDecl *MD, raw_ostream &) = 0; + virtual void mangleCXXVirtualDisplacementMap(const CXXRecordDecl *SrcRD, + const CXXRecordDecl *DstRD, + raw_ostream &Out) = 0; + virtual void mangleCXXThrowInfo(QualType T, bool IsConst, bool IsVolatile, uint32_t NumEntries, raw_ostream &Out) = 0; diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp index 29a95a5103ce..26894bb91eb2 100644 --- a/clang/lib/AST/MicrosoftMangle.cpp +++ b/clang/lib/AST/MicrosoftMangle.cpp @@ -115,6 +115,9 @@ public: void mangleCXXVBTable(const CXXRecordDecl *Derived, ArrayRef BasePath, raw_ostream &Out) override; + void mangleCXXVirtualDisplacementMap(const CXXRecordDecl *SrcRD, + const CXXRecordDecl *DstRD, + raw_ostream &Out) override; void mangleCXXThrowInfo(QualType T, bool IsConst, bool IsVolatile, uint32_t NumEntries, raw_ostream &Out) override; void mangleCXXCatchableTypeArray(QualType T, uint32_t NumEntries, @@ -2395,6 +2398,15 @@ void MicrosoftMangleContextImpl::mangleCXXCatchHandlerType(QualType T, Mangler.getStream() << '.' << Flags; } +void MicrosoftMangleContextImpl::mangleCXXVirtualDisplacementMap( + const CXXRecordDecl *SrcRD, const CXXRecordDecl *DstRD, raw_ostream &Out) { + MicrosoftCXXNameMangler Mangler(*this, Out); + Mangler.getStream() << "\01??_K"; + Mangler.mangleName(SrcRD); + Mangler.getStream() << "$C"; + Mangler.mangleName(DstRD); +} + void MicrosoftMangleContextImpl::mangleCXXThrowInfo(QualType T, bool IsConst, bool IsVolatile, diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp index 4d6a4e288dd3..6538351edf22 100644 --- a/clang/lib/CodeGen/CGClass.cpp +++ b/clang/lib/CodeGen/CGClass.cpp @@ -29,13 +29,12 @@ using namespace clang; using namespace CodeGen; -static CharUnits -ComputeNonVirtualBaseClassOffset(ASTContext &Context, - const CXXRecordDecl *DerivedClass, - CastExpr::path_const_iterator Start, - CastExpr::path_const_iterator End) { +CharUnits CodeGenModule::computeNonVirtualBaseClassOffset( + const CXXRecordDecl *DerivedClass, CastExpr::path_const_iterator Start, + CastExpr::path_const_iterator End) { CharUnits Offset = CharUnits::Zero(); + const ASTContext &Context = getContext(); const CXXRecordDecl *RD = DerivedClass; for (CastExpr::path_const_iterator I = Start; I != End; ++I) { @@ -64,8 +63,7 @@ CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl, assert(PathBegin != PathEnd && "Base path should not be empty!"); CharUnits Offset = - ComputeNonVirtualBaseClassOffset(getContext(), ClassDecl, - PathBegin, PathEnd); + computeNonVirtualBaseClassOffset(ClassDecl, PathBegin, PathEnd); if (Offset.isZero()) return nullptr; @@ -158,9 +156,8 @@ llvm::Value *CodeGenFunction::GetAddressOfBaseClass( // Compute the static offset of the ultimate destination within its // allocating subobject (the virtual base, if there is one, or else // the "complete" object that we see). - CharUnits NonVirtualOffset = - ComputeNonVirtualBaseClassOffset(getContext(), VBase ? VBase : Derived, - Start, PathEnd); + CharUnits NonVirtualOffset = CGM.computeNonVirtualBaseClassOffset( + VBase ? VBase : Derived, Start, PathEnd); // If there's a virtual step, we can sometimes "devirtualize" it. // For now, that's limited to when the derived type is final. diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h index 8e671fa7878c..273fe70d52f3 100644 --- a/clang/lib/CodeGen/CodeGenModule.h +++ b/clang/lib/CodeGen/CodeGenModule.h @@ -732,6 +732,11 @@ public: /// Get a reference to the target of VD. llvm::Constant *GetWeakRefReference(const ValueDecl *VD); + CharUnits + computeNonVirtualBaseClassOffset(const CXXRecordDecl *DerivedClass, + CastExpr::path_const_iterator Start, + CastExpr::path_const_iterator End); + /// Returns the offset from a derived class to a class. Returns null if the /// offset is 0. llvm::Constant * diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp index 3c0aecaa161b..fabdef3d158d 100644 --- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp @@ -247,6 +247,50 @@ public: getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD, llvm::GlobalVariable::LinkageTypes Linkage); + llvm::GlobalVariable * + getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD, + const CXXRecordDecl *DstRD) { + SmallString<256> OutName; + llvm::raw_svector_ostream Out(OutName); + getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out); + Out.flush(); + StringRef MangledName = OutName.str(); + + if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName)) + return VDispMap; + + MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext(); + unsigned NumEntries = 1 + SrcRD->getNumVBases(); + SmallVector Map(NumEntries, + llvm::UndefValue::get(CGM.IntTy)); + Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0); + bool AnyDifferent = false; + for (const auto &I : SrcRD->vbases()) { + const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl(); + if (!DstRD->isVirtuallyDerivedFrom(VBase)) + continue; + + unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase); + unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase); + Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4); + AnyDifferent |= SrcVBIndex != DstVBIndex; + } + // This map would be useless, don't use it. + if (!AnyDifferent) + return nullptr; + + llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size()); + llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map); + llvm::GlobalValue::LinkageTypes Linkage = + SrcRD->isExternallyVisible() && DstRD->isExternallyVisible() + ? llvm::GlobalValue::LinkOnceODRLinkage + : llvm::GlobalValue::InternalLinkage; + auto *VDispMap = new llvm::GlobalVariable( + CGM.getModule(), VDispMapTy, /*Constant=*/true, Linkage, + /*Initializer=*/Init, MangledName); + return VDispMap; + } + void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD, llvm::GlobalVariable *GV) const; @@ -2458,7 +2502,7 @@ MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField, if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) { CharUnits Offs = CharUnits::Zero(); - if (VBTableIndex && RD->getNumVBases()) + if (VBTableIndex) Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset(); fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity())); } @@ -2470,10 +2514,33 @@ MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField, return llvm::ConstantStruct::getAnon(fields); } +// Loading virtual member pointers using the virtual inheritance model +// always results in an adjustment using the vbtable even if the index is +// zero. +// +// This is usually OK because the first slot in the vbtable points +// backwards to the top of the MDC. However, the MDC might be reusing a +// vbptr from an nv-base. In this case, the first slot in the vbtable +// points to the start of the nv-base which introduced the vbptr and *not* +// the MDC. Modify the NonVirtualBaseAdjustment to account for this. +static CharUnits computeOffsetOfBaseWithVBPtr(const ASTContext &Ctx, + const CXXRecordDecl *RD) { + CharUnits Offset = CharUnits::Zero(); + const ASTRecordLayout *Layout = &Ctx.getASTRecordLayout(RD); + while (const CXXRecordDecl *Base = Layout->getBaseSharingVBPtr()) { + Offset += Layout->getBaseClassOffset(Base); + Layout = &Ctx.getASTRecordLayout(Base); + } + return Offset; +} + llvm::Constant * MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, CharUnits offset) { const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); + if (RD->getMSInheritanceModel() == + MSInheritanceAttr::Keyword_virtual_inheritance) + offset -= computeOffsetOfBaseWithVBPtr(getContext(), RD); llvm::Constant *FirstField = llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity()); return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD, @@ -2558,20 +2625,24 @@ MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) { Ty = CGM.PtrDiffTy; } FirstField = CGM.GetAddrOfFunction(MD, Ty); - FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy); } else { auto &VTableContext = CGM.getMicrosoftVTableContext(); MicrosoftVTableContext::MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD); - llvm::Function *Thunk = EmitVirtualMemPtrThunk(MD, ML); - FirstField = llvm::ConstantExpr::getBitCast(Thunk, CGM.VoidPtrTy); + FirstField = EmitVirtualMemPtrThunk(MD, ML); // Include the vfptr adjustment if the method is in a non-primary vftable. NonVirtualBaseAdjustment += ML.VFPtrOffset; if (ML.VBase) VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4; } + if (VBTableIndex == 0 && + RD->getMSInheritanceModel() == + MSInheritanceAttr::Keyword_virtual_inheritance) + NonVirtualBaseAdjustment -= computeOffsetOfBaseWithVBPtr(getContext(), RD); + // The rest of the fields are common with data member pointers. + FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy); return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD, NonVirtualBaseAdjustment, VBTableIndex); } @@ -2829,11 +2900,6 @@ llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress( return Builder.CreateBitCast(Addr, PType); } -static MSInheritanceAttr::Spelling -getInheritanceFromMemptr(const MemberPointerType *MPT) { - return MPT->getMostRecentCXXRecordDecl()->getMSInheritanceModel(); -} - llvm::Value * MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, const CastExpr *E, @@ -2887,10 +2953,11 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, // Decompose src. llvm::Value *FirstField = Src; - llvm::Value *NonVirtualBaseAdjustment = nullptr; - llvm::Value *VirtualBaseAdjustmentOffset = nullptr; - llvm::Value *VBPtrOffset = nullptr; + llvm::Value *NonVirtualBaseAdjustment = getZeroInt(); + llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt(); + llvm::Value *VBPtrOffset = getZeroInt(); MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel(); + MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel(); if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) { // We need to extract values. unsigned I = 0; @@ -2903,25 +2970,95 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++); } + bool IsDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); + const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy; + const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl(); + // For data pointers, we adjust the field offset directly. For functions, we // have a separate field. - llvm::Constant *Adj = getMemberPointerAdjustment(E); - if (Adj) { - Adj = llvm::ConstantExpr::getTruncOrBitCast(Adj, CGM.IntTy); - llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField; - bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); - if (!NVAdjustField) // If this field didn't exist in src, it's zero. - NVAdjustField = getZeroInt(); - if (isDerivedToBase) - NVAdjustField = Builder.CreateNSWSub(NVAdjustField, Adj, "adj"); - else - NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, Adj, "adj"); + llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField; + + // The virtual inheritance model has a quirk: the virtual base table is always + // referenced when dereferencing a member pointer even if the member pointer + // is non-virtual. This is accounted for by adjusting the non-virtual offset + // to point backwards to the top of the MDC from the first VBase. Undo this + // adjustment to normalize the member pointer. + llvm::Value *SrcVBIndexEqZero = + Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt()); + if (SrcInheritance == MSInheritanceAttr::Keyword_virtual_inheritance) { + if (int64_t SrcOffsetToFirstVBase = + computeOffsetOfBaseWithVBPtr(getContext(), SrcRD).getQuantity()) { + llvm::Value *UndoSrcAdjustment = Builder.CreateSelect( + SrcVBIndexEqZero, + llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase), + getZeroInt()); + NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment); + } } - // FIXME PR15713: Support conversions through virtually derived classes. + // A non-zero vbindex implies that we are dealing with a source member in a + // floating virtual base in addition to some non-virtual offset. If the + // vbindex is zero, we are dealing with a source that exists in a non-virtual, + // fixed, base. The difference between these two cases is that the vbindex + + // nvoffset *always* point to the member regardless of what context they are + // evaluated in so long as the vbindex is adjusted. A member inside a fixed + // base requires explicit nv adjustment. + llvm::Constant *BaseClassOffset = llvm::ConstantInt::get( + CGM.IntTy, CGM.computeNonVirtualBaseClassOffset( + DerivedClass, E->path_begin(), E->path_end()) + .getQuantity()); + + llvm::Value *NVDisp; + if (IsDerivedToBase) + NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj"); + else + NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj"); + + NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt()); + + // Update the vbindex to an appropriate value in the destination because + // SrcRD's vbtable might not be a strict prefix of the one in DstRD. + llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero; + if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance) && + MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance)) { + if (llvm::GlobalVariable *VDispMap = + getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) { + llvm::Value *VBIndex = Builder.CreateExactUDiv( + VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4)); + llvm::Value *Idxs[] = {getZeroInt(), VBIndex}; + VirtualBaseAdjustmentOffset = + Builder.CreateLoad(Builder.CreateInBoundsGEP(VDispMap, Idxs)); + + DstVBIndexEqZero = + Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt()); + } + } + + // Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize + // it to the offset of the vbptr. + if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) { + llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get( + CGM.IntTy, + getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity()); + VBPtrOffset = + Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset); + } + + // Likewise, apply a similar adjustment so that dereferencing the member + // pointer correctly accounts for the distance between the start of the first + // virtual base and the top of the MDC. + if (DstInheritance == MSInheritanceAttr::Keyword_virtual_inheritance) { + if (int64_t DstOffsetToFirstVBase = + computeOffsetOfBaseWithVBPtr(getContext(), DstRD).getQuantity()) { + llvm::Value *DoDstAdjustment = Builder.CreateSelect( + DstVBIndexEqZero, + llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase), + getZeroInt()); + NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment); + } + } // Recompose dst from the null struct and the adjusted fields from src. - MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel(); llvm::Value *Dst; if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) { Dst = FirstField; @@ -2930,14 +3067,11 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, unsigned Idx = 0; Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++); if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance)) - Dst = Builder.CreateInsertValue( - Dst, getValueOrZeroInt(NonVirtualBaseAdjustment), Idx++); + Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++); if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) - Dst = Builder.CreateInsertValue( - Dst, getValueOrZeroInt(VBPtrOffset), Idx++); + Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++); if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance)) - Dst = Builder.CreateInsertValue( - Dst, getValueOrZeroInt(VirtualBaseAdjustmentOffset), Idx++); + Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++); } Builder.CreateBr(ContinueBB); @@ -2980,14 +3114,16 @@ llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion( if (CK == CK_ReinterpretMemberPointer) return Src; - MSInheritanceAttr::Spelling SrcInheritance = getInheritanceFromMemptr(SrcTy); - MSInheritanceAttr::Spelling DstInheritance = getInheritanceFromMemptr(DstTy); + const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl(); + const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl(); + MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel(); + MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel(); // Decompose src. llvm::Constant *FirstField = Src; - llvm::Constant *NonVirtualBaseAdjustment = nullptr; - llvm::Constant *VirtualBaseAdjustmentOffset = nullptr; - llvm::Constant *VBPtrOffset = nullptr; + llvm::Constant *NonVirtualBaseAdjustment = getZeroInt(); + llvm::Constant *VirtualBaseAdjustmentOffset = getZeroInt(); + llvm::Constant *VBPtrOffset = getZeroInt(); bool IsFunc = SrcTy->isMemberFunctionPointer(); if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) { // We need to extract values. @@ -3001,27 +3137,95 @@ llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion( VirtualBaseAdjustmentOffset = Src->getAggregateElement(I++); } + bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer); + const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy; + const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl(); + // For data pointers, we adjust the field offset directly. For functions, we // have a separate field. - const MemberPointerType *DerivedTy = - CK == CK_DerivedToBaseMemberPointer ? SrcTy : DstTy; - const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl(); - llvm::Constant *Adj = - CGM.GetNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd); - if (Adj) { - Adj = llvm::ConstantExpr::getTruncOrBitCast(Adj, CGM.IntTy); - llvm::Constant *&NVAdjustField = + llvm::Constant *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField; - bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer); - if (!NVAdjustField) // If this field didn't exist in src, it's zero. - NVAdjustField = getZeroInt(); - if (IsDerivedToBase) - NVAdjustField = llvm::ConstantExpr::getNSWSub(NVAdjustField, Adj); - else - NVAdjustField = llvm::ConstantExpr::getNSWAdd(NVAdjustField, Adj); + + // The virtual inheritance model has a quirk: the virtual base table is always + // referenced when dereferencing a member pointer even if the member pointer + // is non-virtual. This is accounted for by adjusting the non-virtual offset + // to point backwards to the top of the MDC from the first VBase. Undo this + // adjustment to normalize the member pointer. + llvm::Constant *SrcVBIndexEqZero = llvm::ConstantExpr::getICmp( + llvm::ICmpInst::ICMP_EQ, VirtualBaseAdjustmentOffset, getZeroInt()); + if (SrcInheritance == MSInheritanceAttr::Keyword_virtual_inheritance) { + llvm::Constant *SrcOffsetToFirstVBase = llvm::ConstantInt::get( + CGM.IntTy, + computeOffsetOfBaseWithVBPtr(getContext(), SrcRD).getQuantity()); + llvm::Constant *UndoSrcAdjustment = llvm::ConstantExpr::getSelect( + SrcVBIndexEqZero, SrcOffsetToFirstVBase, getZeroInt()); + NVAdjustField = + llvm::ConstantExpr::getNSWAdd(NVAdjustField, UndoSrcAdjustment); } - // FIXME PR15713: Support conversions through virtually derived classes. + // A non-zero vbindex implies that we are dealing with a source member in a + // floating virtual base in addition to some non-virtual offset. If the + // vbindex is zero, we are dealing with a source that exists in a non-virtual, + // fixed, base. The difference between these two cases is that the vbindex + + // nvoffset *always* point to the member regardless of what context they are + // evaluated in so long as the vbindex is adjusted. A member inside a fixed + // base requires explicit nv adjustment. + llvm::Constant *BaseClassOffset = llvm::ConstantInt::get( + CGM.IntTy, + CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd) + .getQuantity()); + + llvm::Constant *NVDisp; + if (IsDerivedToBase) + NVDisp = llvm::ConstantExpr::getNSWSub(NVAdjustField, BaseClassOffset); + else + NVDisp = llvm::ConstantExpr::getNSWAdd(NVAdjustField, BaseClassOffset); + + // An nv-base adjustment must only be made if the vbindex is zero (or does not + // exist). + NVAdjustField = + llvm::ConstantExpr::getSelect(SrcVBIndexEqZero, NVDisp, getZeroInt()); + + // Update the vbindex to an appropriate value in the destination because + // SrcRD's vbtable might not be a strict prefix of the one in DstRD. + llvm::Constant *DstVBIndexEqZero = SrcVBIndexEqZero; + if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance) && + MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance)) { + if (llvm::GlobalVariable *VDispMap = + getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) { + llvm::Constant *Mapping = VDispMap->getInitializer(); + llvm::Constant *VBIndex = llvm::ConstantExpr::getUDiv( + VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4), + /*IsExact=*/true); + VirtualBaseAdjustmentOffset = Mapping->getAggregateElement(VBIndex); + + DstVBIndexEqZero = llvm::ConstantExpr::getICmp( + llvm::ICmpInst::ICMP_EQ, VirtualBaseAdjustmentOffset, getZeroInt()); + } + } + + // Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize + // it to the offset of the vbptr. + if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) { + llvm::Constant *DstVBPtrOffset = llvm::ConstantInt::get( + CGM.IntTy, + getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity()); + VBPtrOffset = llvm::ConstantExpr::getSelect(DstVBIndexEqZero, getZeroInt(), + DstVBPtrOffset); + } + + // Likewise, apply a similar adjustment so that dereferencing the member + // pointer correctly accounts for the distance between the start of the first + // virtual base and the top of the MDC. + if (DstInheritance == MSInheritanceAttr::Keyword_virtual_inheritance) { + llvm::Constant *DstOffsetToFirstVBase = llvm::ConstantInt::get( + CGM.IntTy, + computeOffsetOfBaseWithVBPtr(getContext(), DstRD).getQuantity()); + llvm::Constant *DoDstAdjustment = llvm::ConstantExpr::getSelect( + DstVBIndexEqZero, DstOffsetToFirstVBase, getZeroInt()); + NVAdjustField = + llvm::ConstantExpr::getNSWSub(NVAdjustField, DoDstAdjustment); + } // Recompose dst from the null struct and the adjusted fields from src. if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) @@ -3030,11 +3234,11 @@ llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion( llvm::SmallVector Fields; Fields.push_back(FirstField); if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance)) - Fields.push_back(getConstantOrZeroInt(NonVirtualBaseAdjustment)); + Fields.push_back(NonVirtualBaseAdjustment); if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) - Fields.push_back(getConstantOrZeroInt(VBPtrOffset)); + Fields.push_back(VBPtrOffset); if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance)) - Fields.push_back(getConstantOrZeroInt(VirtualBaseAdjustmentOffset)); + Fields.push_back(VirtualBaseAdjustmentOffset); return llvm::ConstantStruct::getAnon(Fields); } diff --git a/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp b/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp index 8cb4a1f8bd24..a509d57194f2 100644 --- a/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp +++ b/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp @@ -541,9 +541,13 @@ void (D::*convertCToD(void (C::*mp)()))() { // // memptr.convert: ; preds = %entry // CHECK: extractvalue { i8*, i32, i32 } %{{.*}}, 0 -// CHECK: extractvalue { i8*, i32, i32 } %{{.*}}, 1 -// CHECK: extractvalue { i8*, i32, i32 } %{{.*}}, 2 -// CHECK: %[[adj:.*]] = add nsw i32 %{{.*}}, 4 +// CHECK: %[[nvoff:.*]] = extractvalue { i8*, i32, i32 } %{{.*}}, 1 +// CHECK: %[[vbidx:.*]] = extractvalue { i8*, i32, i32 } %{{.*}}, 2 +// CHECK: %[[is_nvbase:.*]] = icmp eq i32 %[[vbidx]], 0 +// CHECK: %[[nv_disp:.*]] = add nsw i32 %[[nvoff]], 4 +// CHECK: %[[nv_adj:.*]] = select i1 %[[is_nvbase]], i32 %[[nv_disp]], i32 0 +// CHECK: %[[dst_adj:.*]] = select i1 %[[is_nvbase]], i32 4, i32 0 +// CHECK: %[[adj:.*]] = sub nsw i32 %[[nv_adj]], %[[dst_adj]] // CHECK: insertvalue { i8*, i32, i32 } undef, i8* {{.*}}, 0 // CHECK: insertvalue { i8*, i32, i32 } {{.*}}, i32 %[[adj]], 1 // CHECK: insertvalue { i8*, i32, i32 } {{.*}}, i32 {{.*}}, 2 @@ -712,3 +716,16 @@ int foo(A *a, int A::*mp) { } #endif #endif + +namespace pr23878 { +struct A { virtual void g(); }; +struct B { virtual void f(); }; +struct C : virtual B { void f(); }; +struct D : A, C {}; + +typedef void (D::*DMemPtrTy)(); + +// CHECK-LABEL: define void @"\01?get_memptr@pr23878@@YAP8D@1@AEXXZXZ" +// CHECK: @"\01??_9C@pr23878@@$BA@AE" to i8*), i32 0, i32 4 +DMemPtrTy get_memptr() { return &D::f; } +}