From 6fa20cfea320bfcc45e7fa70a2ead481df8a4ce8 Mon Sep 17 00:00:00 2001 From: "Ivan A. Kosarev" Date: Thu, 5 Oct 2017 10:47:51 +0000 Subject: [CodeGen] Unify generation of scalar and struct-path TBAA tags This patch makes it possible to produce access tags in a uniform manner regardless whether the resulting tag will be a scalar or a struct-path one. getAccessTagInfo() now takes care of the actual translation of access descriptors to tags and can handle all kinds of accesses. Facilities that specific to scalar accesses are eliminated. Some more details: * DecorateInstructionWithTBAA() is not responsible for conversion of types to access tags anymore. Instead, it takes an access descriptor (TBAAAccessInfo) and generates corresponding access tag from it. * getTBAAInfoForVTablePtr() reworked to getTBAAVTablePtrAccessInfo() that now returns the virtual-pointer access descriptor and not the virtual-point type metadata. * Added function getTBAAMayAliasAccessInfo() that returns the descriptor for may-alias accesses. * getTBAAStructTagInfo() renamed to getTBAAAccessTagInfo() as now it is the only way to generate access tag by a given access descriptor. It is capable of producing both scalar and struct-path tags, depending on options and availability of the base access type. getTBAAScalarTagInfo() and its cache ScalarTagMetadataCache are eliminated. * Now that we do not need to care about whether the resulting access tag should be a scalar or struct-path one, getTBAAStructTypeInfo() is renamed to getBaseTypeInfo(). * Added function getTBAAAccessInfo() that constructs access descriptor by a given QualType access type. This is part of D37826 reworked to be a separate patch to simplify review. Differential Revision: https://reviews.llvm.org/D38503 llvm-svn: 314977 --- clang/lib/CodeGen/CGExpr.cpp | 78 +++++++++++++++++++++----------------------- 1 file changed, 38 insertions(+), 40 deletions(-) (limited to 'clang/lib/CodeGen/CGExpr.cpp') diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp index 74ad9dcf4630..1bb57b6e2bb5 100644 --- a/clang/lib/CodeGen/CGExpr.cpp +++ b/clang/lib/CodeGen/CGExpr.cpp @@ -1174,8 +1174,7 @@ LValue CodeGenFunction::EmitLValue(const Expr *E) { llvm::Value *V = LV.getPointer(); Scope.ForceCleanup({&V}); return LValue::MakeAddr(Address(V, LV.getAlignment()), LV.getType(), - getContext(), LV.getBaseInfo(), - LV.getTBAAAccessType()); + getContext(), LV.getBaseInfo(), LV.getTBAAInfo()); } // FIXME: Is it possible to create an ExprWithCleanups that produces a // bitfield lvalue or some other non-simple lvalue? @@ -1514,7 +1513,7 @@ llvm::Value *CodeGenFunction::EmitLoadOfScalar(Address Addr, bool Volatile, // Atomic operations have to be done on integral types. LValue AtomicLValue = - LValue::MakeAddr(Addr, Ty, getContext(), BaseInfo, TBAAInfo.AccessType); + LValue::MakeAddr(Addr, Ty, getContext(), BaseInfo, TBAAInfo); if (Ty->isAtomicType() || LValueIsSuitableForInlineAtomic(AtomicLValue)) { return EmitAtomicLoad(AtomicLValue, Loc).getScalarVal(); } @@ -1525,14 +1524,10 @@ llvm::Value *CodeGenFunction::EmitLoadOfScalar(Address Addr, bool Volatile, Load->getContext(), llvm::ConstantAsMetadata::get(Builder.getInt32(1))); Load->setMetadata(CGM.getModule().getMDKindID("nontemporal"), Node); } - if (TBAAInfo.AccessType) { - bool MayAlias = BaseInfo.getMayAlias(); - llvm::MDNode *TBAA = MayAlias - ? CGM.getTBAAMayAliasTypeInfo() - : CGM.getTBAAStructTagInfo(TBAAInfo); - if (TBAA) - CGM.DecorateInstructionWithTBAA(Load, TBAA, MayAlias); - } + + if (BaseInfo.getMayAlias()) + TBAAInfo = CGM.getTBAAMayAliasAccessInfo(); + CGM.DecorateInstructionWithTBAA(Load, TBAAInfo); if (EmitScalarRangeCheck(Load, Ty, Loc)) { // In order to prevent the optimizer from throwing away the check, don't @@ -1599,7 +1594,7 @@ void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, Address Addr, Value = EmitToMemory(Value, Ty); LValue AtomicLValue = - LValue::MakeAddr(Addr, Ty, getContext(), BaseInfo, TBAAInfo.AccessType); + LValue::MakeAddr(Addr, Ty, getContext(), BaseInfo, TBAAInfo); if (Ty->isAtomicType() || (!isInit && LValueIsSuitableForInlineAtomic(AtomicLValue))) { EmitAtomicStore(RValue::get(Value), AtomicLValue, isInit); @@ -1613,14 +1608,10 @@ void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, Address Addr, llvm::ConstantAsMetadata::get(Builder.getInt32(1))); Store->setMetadata(CGM.getModule().getMDKindID("nontemporal"), Node); } - if (TBAAInfo.AccessType) { - bool MayAlias = BaseInfo.getMayAlias(); - llvm::MDNode *TBAA = MayAlias - ? CGM.getTBAAMayAliasTypeInfo() - : CGM.getTBAAStructTagInfo(TBAAInfo); - if (TBAA) - CGM.DecorateInstructionWithTBAA(Store, TBAA, MayAlias); - } + + if (BaseInfo.getMayAlias()) + TBAAInfo = CGM.getTBAAMayAliasAccessInfo(); + CGM.DecorateInstructionWithTBAA(Store, TBAAInfo); } void CodeGenFunction::EmitStoreOfScalar(llvm::Value *value, LValue lvalue, @@ -3727,12 +3718,9 @@ LValue CodeGenFunction::EmitLValueForField(LValue base, // Loading the reference will disable path-aware TBAA. TBAAPath = false; - if (CGM.shouldUseTBAA()) { - llvm::MDNode *tbaa = mayAlias ? CGM.getTBAAMayAliasTypeInfo() : - CGM.getTBAATypeInfo(type); - if (tbaa) - CGM.DecorateInstructionWithTBAA(load, tbaa); - } + TBAAAccessInfo TBAAInfo = mayAlias ? CGM.getTBAAMayAliasAccessInfo() : + CGM.getTBAAAccessInfo(type); + CGM.DecorateInstructionWithTBAA(load, TBAAInfo); mayAlias = false; type = refType->getPointeeType(); @@ -3762,17 +3750,33 @@ LValue CodeGenFunction::EmitLValueForField(LValue base, LValue LV = MakeAddrLValue(addr, type, FieldBaseInfo); LV.getQuals().addCVRQualifiers(cvr); - if (TBAAPath) { + + // Fields of may_alias structs act like 'char' for TBAA purposes. + // FIXME: this should get propagated down through anonymous structs + // and unions. + if (mayAlias) { + LV.setTBAAInfo(CGM.getTBAAMayAliasAccessInfo()); + } else if (TBAAPath) { + // If no base type been assigned for the base access, then try to generate + // one for this base lvalue. + TBAAAccessInfo TBAAInfo = base.getTBAAInfo(); + if (!TBAAInfo.BaseType) { + TBAAInfo.BaseType = CGM.getTBAABaseTypeInfo(base.getType()); + assert(!TBAAInfo.Offset && + "Nonzero offset for an access with no base type!"); + } + + // Adjust offset to be relative to the base type. const ASTRecordLayout &Layout = getContext().getASTRecordLayout(field->getParent()); - // Set the base type to be the base type of the base LValue and - // update offset to be relative to the base type. unsigned CharWidth = getContext().getCharWidth(); - TBAAAccessInfo TBAAInfo = mayAlias ? - TBAAAccessInfo(CGM.getTBAAMayAliasTypeInfo()) : - TBAAAccessInfo(base.getTBAAInfo().BaseType, CGM.getTBAATypeInfo(type), - base.getTBAAInfo().Offset + Layout.getFieldOffset( - field->getFieldIndex()) / CharWidth); + if (TBAAInfo.BaseType) + TBAAInfo.Offset += + Layout.getFieldOffset(field->getFieldIndex()) / CharWidth; + + // Update the final access type. + TBAAInfo.AccessType = LV.getTBAAInfo().AccessType; + LV.setTBAAInfo(TBAAInfo); } @@ -3780,12 +3784,6 @@ LValue CodeGenFunction::EmitLValueForField(LValue base, if (LV.getQuals().getObjCGCAttr() == Qualifiers::Weak) LV.getQuals().removeObjCGCAttr(); - // Fields of may_alias structs act like 'char' for TBAA purposes. - // FIXME: this should get propagated down through anonymous structs - // and unions. - if (mayAlias && LV.getTBAAAccessType()) - LV.setTBAAAccessType(CGM.getTBAAMayAliasTypeInfo()); - return LV; } -- cgit v1.2.3