forked from OSchip/llvm-project
[MS ABI] Unify constant and non-constant member pointer conversion
We had two separate paths for member pointer conversion: one which takes a constant and another which takes an arbitrary value. In the latter case, we are permitted to construct arbitrary instructions. It turns out that the bulk of the member pointer conversion is sharable if we construct an artificial IRBuilder. llvm-svn: 240921
This commit is contained in:
David Majnemer
parent
d94330440a
commit
0d9ad687c7
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@ -603,6 +603,12 @@ public:
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llvm::Value *Base, llvm::Value *MemPtr,
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const MemberPointerType *MPT) override;
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llvm::Value *EmitNonNullMemberPointerConversion(
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const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
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CastKind CK, CastExpr::path_const_iterator PathBegin,
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CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
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CGBuilderTy &Builder);
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llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
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const CastExpr *E,
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llvm::Value *Src) override;
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@ -2931,13 +2937,37 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
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Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
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CGF.EmitBlock(ConvertBB);
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llvm::Value *Dst = EmitNonNullMemberPointerConversion(
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SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,
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Builder);
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Builder.CreateBr(ContinueBB);
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// In the continuation, choose between DstNull and Dst.
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CGF.EmitBlock(ContinueBB);
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llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
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Phi->addIncoming(DstNull, OriginalBB);
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Phi->addIncoming(Dst, ConvertBB);
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return Phi;
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}
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llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
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const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
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CastExpr::path_const_iterator PathBegin,
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CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
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CGBuilderTy &Builder) {
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const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
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const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
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MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel();
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MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel();
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bool IsFunc = SrcTy->isMemberFunctionPointer();
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bool IsConstant = isa<llvm::Constant>(Src);
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// Decompose src.
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llvm::Value *FirstField = Src;
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llvm::Value *NonVirtualBaseAdjustment = getZeroInt();
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llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();
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llvm::Value *VBPtrOffset = getZeroInt();
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MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel();
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MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel();
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if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) {
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// We need to extract values.
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unsigned I = 0;
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@ -2950,7 +2980,7 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
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VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
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}
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bool IsDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);
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bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
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const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
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const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
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@ -2984,9 +3014,9 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
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// evaluated in so long as the vbindex is adjusted. A member inside a fixed
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// base requires explicit nv adjustment.
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llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
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CGM.IntTy, CGM.computeNonVirtualBaseClassOffset(
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DerivedClass, E->path_begin(), E->path_end())
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.getQuantity());
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CGM.IntTy,
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CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
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.getQuantity());
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llvm::Value *NVDisp;
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if (IsDerivedToBase)
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@ -3005,9 +3035,15 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
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getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
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llvm::Value *VBIndex = Builder.CreateExactUDiv(
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VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));
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llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
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VirtualBaseAdjustmentOffset =
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Builder.CreateLoad(Builder.CreateInBoundsGEP(VDispMap, Idxs));
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if (IsConstant) {
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llvm::Constant *Mapping = VDispMap->getInitializer();
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VirtualBaseAdjustmentOffset =
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Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));
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} else {
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llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
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VirtualBaseAdjustmentOffset =
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Builder.CreateLoad(Builder.CreateInBoundsGEP(VDispMap, Idxs));
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}
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DstVBIndexEqZero =
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Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
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@ -3043,7 +3079,7 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
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if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) {
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Dst = FirstField;
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} else {
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Dst = llvm::UndefValue::get(DstNull->getType());
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Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
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unsigned Idx = 0;
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Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
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if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance))
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@ -3053,14 +3089,7 @@ MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
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if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance))
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Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);
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}
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Builder.CreateBr(ContinueBB);
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// In the continuation, choose between DstNull and Dst.
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CGF.EmitBlock(ContinueBB);
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llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
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Phi->addIncoming(DstNull, OriginalBB);
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Phi->addIncoming(Dst, ConvertBB);
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return Phi;
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return Dst;
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}
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llvm::Constant *
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@ -3096,128 +3125,12 @@ llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(
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const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
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const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
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MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel();
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MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel();
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// Decompose src.
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llvm::Constant *FirstField = Src;
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llvm::Constant *NonVirtualBaseAdjustment = getZeroInt();
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llvm::Constant *VirtualBaseAdjustmentOffset = getZeroInt();
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llvm::Constant *VBPtrOffset = getZeroInt();
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bool IsFunc = SrcTy->isMemberFunctionPointer();
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if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) {
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// We need to extract values.
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unsigned I = 0;
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FirstField = Src->getAggregateElement(I++);
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if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance))
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NonVirtualBaseAdjustment = Src->getAggregateElement(I++);
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if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance))
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VBPtrOffset = Src->getAggregateElement(I++);
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if (MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance))
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VirtualBaseAdjustmentOffset = Src->getAggregateElement(I++);
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}
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CGBuilderTy Builder(CGM.getLLVMContext());
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auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(
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SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));
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bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
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const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
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const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
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// For data pointers, we adjust the field offset directly. For functions, we
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// have a separate field.
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llvm::Constant *&NVAdjustField =
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IsFunc ? NonVirtualBaseAdjustment : FirstField;
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// The virtual inheritance model has a quirk: the virtual base table is always
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// referenced when dereferencing a member pointer even if the member pointer
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// is non-virtual. This is accounted for by adjusting the non-virtual offset
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// to point backwards to the top of the MDC from the first VBase. Undo this
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// adjustment to normalize the member pointer.
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llvm::Constant *SrcVBIndexEqZero = llvm::ConstantExpr::getICmp(
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llvm::ICmpInst::ICMP_EQ, VirtualBaseAdjustmentOffset, getZeroInt());
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if (SrcInheritance == MSInheritanceAttr::Keyword_virtual_inheritance) {
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llvm::Constant *SrcOffsetToFirstVBase = llvm::ConstantInt::get(
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CGM.IntTy, getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity());
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llvm::Constant *UndoSrcAdjustment = llvm::ConstantExpr::getSelect(
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SrcVBIndexEqZero, SrcOffsetToFirstVBase, getZeroInt());
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NVAdjustField =
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llvm::ConstantExpr::getNSWAdd(NVAdjustField, UndoSrcAdjustment);
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}
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// A non-zero vbindex implies that we are dealing with a source member in a
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// floating virtual base in addition to some non-virtual offset. If the
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// vbindex is zero, we are dealing with a source that exists in a non-virtual,
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// fixed, base. The difference between these two cases is that the vbindex +
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// nvoffset *always* point to the member regardless of what context they are
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// evaluated in so long as the vbindex is adjusted. A member inside a fixed
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// base requires explicit nv adjustment.
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llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
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CGM.IntTy,
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CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
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.getQuantity());
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llvm::Constant *NVDisp;
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if (IsDerivedToBase)
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NVDisp = llvm::ConstantExpr::getNSWSub(NVAdjustField, BaseClassOffset);
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else
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NVDisp = llvm::ConstantExpr::getNSWAdd(NVAdjustField, BaseClassOffset);
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// An nv-base adjustment must only be made if the vbindex is zero (or does not
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// exist).
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NVAdjustField =
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llvm::ConstantExpr::getSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());
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// Update the vbindex to an appropriate value in the destination because
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// SrcRD's vbtable might not be a strict prefix of the one in DstRD.
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llvm::Constant *DstVBIndexEqZero = SrcVBIndexEqZero;
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if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance) &&
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MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance)) {
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if (llvm::GlobalVariable *VDispMap =
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getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
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llvm::Constant *Mapping = VDispMap->getInitializer();
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llvm::Constant *VBIndex = llvm::ConstantExpr::getUDiv(
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VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4),
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/*IsExact=*/true);
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VirtualBaseAdjustmentOffset = Mapping->getAggregateElement(VBIndex);
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DstVBIndexEqZero = llvm::ConstantExpr::getICmp(
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llvm::ICmpInst::ICMP_EQ, VirtualBaseAdjustmentOffset, getZeroInt());
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}
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}
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// Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize
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// it to the offset of the vbptr.
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if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) {
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llvm::Constant *DstVBPtrOffset = llvm::ConstantInt::get(
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CGM.IntTy,
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getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());
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VBPtrOffset = llvm::ConstantExpr::getSelect(DstVBIndexEqZero, getZeroInt(),
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DstVBPtrOffset);
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}
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// Likewise, apply a similar adjustment so that dereferencing the member
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// pointer correctly accounts for the distance between the start of the first
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// virtual base and the top of the MDC.
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if (DstInheritance == MSInheritanceAttr::Keyword_virtual_inheritance) {
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llvm::Constant *DstOffsetToFirstVBase = llvm::ConstantInt::get(
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CGM.IntTy, getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity());
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llvm::Constant *DoDstAdjustment = llvm::ConstantExpr::getSelect(
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DstVBIndexEqZero, DstOffsetToFirstVBase, getZeroInt());
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NVAdjustField =
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llvm::ConstantExpr::getNSWSub(NVAdjustField, DoDstAdjustment);
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}
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// Recompose dst from the null struct and the adjusted fields from src.
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if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance))
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return FirstField;
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llvm::SmallVector<llvm::Constant *, 4> Fields;
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Fields.push_back(FirstField);
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if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance))
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Fields.push_back(NonVirtualBaseAdjustment);
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if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance))
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Fields.push_back(VBPtrOffset);
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if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance))
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Fields.push_back(VirtualBaseAdjustmentOffset);
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return llvm::ConstantStruct::getAnon(Fields);
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return Dst;
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}
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llvm::Value *MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
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