diff options
Diffstat (limited to 'lib/Analysis')
-rw-r--r-- | lib/Analysis/TypeBasedAliasAnalysis.cpp | 62 |
1 files changed, 60 insertions, 2 deletions
diff --git a/lib/Analysis/TypeBasedAliasAnalysis.cpp b/lib/Analysis/TypeBasedAliasAnalysis.cpp index c14c593bf7..442145f596 100644 --- a/lib/Analysis/TypeBasedAliasAnalysis.cpp +++ b/lib/Analysis/TypeBasedAliasAnalysis.cpp @@ -376,7 +376,7 @@ bool TypeBasedAliasAnalysis::pointsToConstantMemory(const Location &Loc, // If this is an "immutable" type, we can assume the pointer is pointing // to constant memory. - if (TBAANode(M).TypeIsImmutable()) + if (!EnableStructPathTBAA && TBAANode(M).TypeIsImmutable()) return true; return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal); @@ -392,7 +392,7 @@ TypeBasedAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) { // If this is an "immutable" type, we can assume the call doesn't write // to memory. if (const MDNode *M = CS.getInstruction()->getMetadata(LLVMContext::MD_tbaa)) - if (TBAANode(M).TypeIsImmutable()) + if (!EnableStructPathTBAA && TBAANode(M).TypeIsImmutable()) Min = OnlyReadsMemory; return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min); @@ -434,3 +434,61 @@ TypeBasedAliasAnalysis::getModRefInfo(ImmutableCallSite CS1, return AliasAnalysis::getModRefInfo(CS1, CS2); } + +MDNode *MDNode::getMostGenericTBAA(MDNode *A, MDNode *B) { + if (!A || !B) + return NULL; + + if (A == B) + return A; + + // For struct-path aware TBAA, we use the access type of the tag. + if (EnableStructPathTBAA) { + A = cast_or_null<MDNode>(A->getOperand(1)); + if (!A) return 0; + B = cast_or_null<MDNode>(B->getOperand(1)); + if (!B) return 0; + } + + SmallVector<MDNode *, 4> PathA; + MDNode *T = A; + while (T) { + PathA.push_back(T); + if (EnableStructPathTBAA) + T = T->getNumOperands() >= 3 ? cast_or_null<MDNode>(T->getOperand(2)) : 0; + else + T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0; + } + + SmallVector<MDNode *, 4> PathB; + T = B; + while (T) { + PathB.push_back(T); + if (EnableStructPathTBAA) + T = T->getNumOperands() >= 3 ? cast_or_null<MDNode>(T->getOperand(2)) : 0; + else + T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0; + } + + int IA = PathA.size() - 1; + int IB = PathB.size() - 1; + + MDNode *Ret = 0; + while (IA >= 0 && IB >=0) { + if (PathA[IA] == PathB[IB]) + Ret = PathA[IA]; + else + break; + --IA; + --IB; + } + if (!EnableStructPathTBAA) + return Ret; + + if (!Ret) + return 0; + // We need to convert from a type node to a tag node. + Type *Int64 = IntegerType::get(A->getContext(), 64); + Value *Ops[3] = { Ret, Ret, ConstantInt::get(Int64, 0) }; + return MDNode::get(A->getContext(), Ops); +} |