X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FBasicAliasAnalysis.cpp;h=4139336f268bfbb9d766c89fbf361c6ec88a5d26;hb=b78821d380b6f9514bd3b56b1c27ba367660228b;hp=3d10a5fd4d76fc6a0dcd776346049729d0e5b937;hpb=c122c625ce018e33f25ba35150bed10183ae2b40;p=oota-llvm.git diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index 3d10a5fd4d7..4139336f268 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -13,27 +13,28 @@ // //===----------------------------------------------------------------------===// -#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/Analysis/Passes.h" -#include "llvm/Constants.h" -#include "llvm/DerivedTypes.h" -#include "llvm/Function.h" -#include "llvm/GlobalAlias.h" -#include "llvm/GlobalVariable.h" -#include "llvm/Instructions.h" -#include "llvm/IntrinsicInst.h" -#include "llvm/LLVMContext.h" -#include "llvm/Operator.h" -#include "llvm/Pass.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/Analysis/CaptureTracking.h" -#include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/Analysis/ValueTracking.h" -#include "llvm/Target/TargetData.h" -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/ADT/SmallVector.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/GlobalAlias.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Operator.h" +#include "llvm/Pass.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/GetElementPtrTypeIterator.h" +#include "llvm/Target/TargetLibraryInfo.h" #include using namespace llvm; @@ -41,22 +42,6 @@ using namespace llvm; // Useful predicates //===----------------------------------------------------------------------===// -/// isKnownNonNull - Return true if we know that the specified value is never -/// null. -static bool isKnownNonNull(const Value *V) { - // Alloca never returns null, malloc might. - if (isa(V)) return true; - - // A byval argument is never null. - if (const Argument *A = dyn_cast(V)) - return A->hasByValAttr(); - - // Global values are not null unless extern weak. - if (const GlobalValue *GV = dyn_cast(V)) - return !GV->hasExternalWeakLinkage(); - return false; -} - /// isNonEscapingLocalObject - Return true if the pointer is to a function-local /// object that never escapes from the function. static bool isNonEscapingLocalObject(const Value *V) { @@ -73,12 +58,12 @@ static bool isNonEscapingLocalObject(const Value *V) { // then it has not escaped before entering the function. Check if it escapes // inside the function. if (const Argument *A = dyn_cast(V)) - if (A->hasByValAttr() || A->hasNoAliasAttr()) { - // Don't bother analyzing arguments already known not to escape. - if (A->hasNoCaptureAttr()) - return true; + if (A->hasByValAttr() || A->hasNoAliasAttr()) + // Note even if the argument is marked nocapture we still need to check + // for copies made inside the function. The nocapture attribute only + // specifies that there are no copies made that outlive the function. return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true); - } + return false; } @@ -99,50 +84,32 @@ static bool isEscapeSource(const Value *V) { /// getObjectSize - Return the size of the object specified by V, or /// UnknownSize if unknown. -static uint64_t getObjectSize(const Value *V, const TargetData &TD) { - const Type *AccessTy; - if (const GlobalVariable *GV = dyn_cast(V)) { - if (!GV->hasDefinitiveInitializer()) - return AliasAnalysis::UnknownSize; - AccessTy = GV->getType()->getElementType(); - } else if (const AllocaInst *AI = dyn_cast(V)) { - if (!AI->isArrayAllocation()) - AccessTy = AI->getType()->getElementType(); - else - return AliasAnalysis::UnknownSize; - } else if (const CallInst* CI = extractMallocCall(V)) { - if (!isArrayMalloc(V, &TD)) - // The size is the argument to the malloc call. - if (const ConstantInt* C = dyn_cast(CI->getArgOperand(0))) - return C->getZExtValue(); - return AliasAnalysis::UnknownSize; - } else if (const Argument *A = dyn_cast(V)) { - if (A->hasByValAttr()) - AccessTy = cast(A->getType())->getElementType(); - else - return AliasAnalysis::UnknownSize; - } else { - return AliasAnalysis::UnknownSize; - } - - if (AccessTy->isSized()) - return TD.getTypeAllocSize(AccessTy); +static uint64_t getObjectSize(const Value *V, const DataLayout &TD, + const TargetLibraryInfo &TLI, + bool RoundToAlign = false) { + uint64_t Size; + if (getUnderlyingObjectSize(V, Size, &TD, &TLI, RoundToAlign)) + return Size; return AliasAnalysis::UnknownSize; } /// isObjectSmallerThan - Return true if we can prove that the object specified /// by V is smaller than Size. static bool isObjectSmallerThan(const Value *V, uint64_t Size, - const TargetData &TD) { - uint64_t ObjectSize = getObjectSize(V, TD); + const DataLayout &TD, + const TargetLibraryInfo &TLI) { + // This function needs to use the aligned object size because we allow + // reads a bit past the end given sufficient alignment. + uint64_t ObjectSize = getObjectSize(V, TD, TLI, /*RoundToAlign*/true); + return ObjectSize != AliasAnalysis::UnknownSize && ObjectSize < Size; } /// isObjectSize - Return true if we can prove that the object specified /// by V has size Size. static bool isObjectSize(const Value *V, uint64_t Size, - const TargetData &TD) { - uint64_t ObjectSize = getObjectSize(V, TD); + const DataLayout &TD, const TargetLibraryInfo &TLI) { + uint64_t ObjectSize = getObjectSize(V, TD, TLI); return ObjectSize != AliasAnalysis::UnknownSize && ObjectSize == Size; } @@ -161,6 +128,15 @@ namespace { const Value *V; ExtensionKind Extension; int64_t Scale; + + bool operator==(const VariableGEPIndex &Other) const { + return V == Other.V && Extension == Other.Extension && + Scale == Other.Scale; + } + + bool operator!=(const VariableGEPIndex &Other) const { + return !operator==(Other); + } }; } @@ -175,7 +151,7 @@ namespace { /// represented in the result. static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset, ExtensionKind &Extension, - const TargetData &TD, unsigned Depth) { + const DataLayout &TD, unsigned Depth) { assert(V->getType()->isIntegerTy() && "Not an integer value"); // Limit our recursion depth. @@ -250,14 +226,14 @@ static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset, /// specified amount, but which may have other unrepresented high bits. As such, /// the gep cannot necessarily be reconstructed from its decomposed form. /// -/// When TargetData is around, this function is capable of analyzing everything +/// When DataLayout is around, this function is capable of analyzing everything /// that GetUnderlyingObject can look through. When not, it just looks /// through pointer casts. /// static const Value * DecomposeGEPExpression(const Value *V, int64_t &BaseOffs, SmallVectorImpl &VarIndices, - const TargetData *TD) { + const DataLayout *TD) { // Limit recursion depth to limit compile time in crazy cases. unsigned MaxLookup = 6; @@ -301,7 +277,7 @@ DecomposeGEPExpression(const Value *V, int64_t &BaseOffs, ->getElementType()->isSized()) return V; - // If we are lacking TargetData information, we can't compute the offets of + // If we are lacking DataLayout information, we can't compute the offets of // elements computed by GEPs. However, we can handle bitcast equivalent // GEPs. if (TD == 0) { @@ -317,7 +293,7 @@ DecomposeGEPExpression(const Value *V, int64_t &BaseOffs, E = GEPOp->op_end(); I != E; ++I) { Value *Index = *I; // Compute the (potentially symbolic) offset in bytes for this index. - if (const StructType *STy = dyn_cast(*GTI++)) { + if (StructType *STy = dyn_cast(*GTI++)) { // For a struct, add the member offset. unsigned FieldNo = cast(Index)->getZExtValue(); if (FieldNo == 0) continue; @@ -374,7 +350,8 @@ DecomposeGEPExpression(const Value *V, int64_t &BaseOffs, } if (Scale) { - VariableGEPIndex Entry = {Index, Extension, Scale}; + VariableGEPIndex Entry = {Index, Extension, + static_cast(Scale)}; VarIndices.push_back(Entry); } } @@ -461,6 +438,7 @@ namespace { virtual void getAnalysisUsage(AnalysisUsage &AU) const { AU.addRequired(); + AU.addRequired(); } virtual AliasResult alias(const Location &LocA, @@ -470,7 +448,11 @@ namespace { "BasicAliasAnalysis doesn't support interprocedural queries."); AliasResult Alias = aliasCheck(LocA.Ptr, LocA.Size, LocA.TBAATag, LocB.Ptr, LocB.Size, LocB.TBAATag); - AliasCache.clear(); + // AliasCache rarely has more than 1 or 2 elements, always use + // shrink_and_clear so it quickly returns to the inline capacity of the + // SmallDenseMap if it ever grows larger. + // FIXME: This should really be shrink_to_inline_capacity_and_clear(). + AliasCache.shrink_and_clear(); return Alias; } @@ -508,7 +490,7 @@ namespace { private: // AliasCache - Track alias queries to guard against recursion. typedef std::pair LocPair; - typedef DenseMap AliasCacheTy; + typedef SmallDenseMap AliasCacheTy; AliasCacheTy AliasCache; // Visited - Track instructions visited by pointsToConstantMemory. @@ -517,6 +499,7 @@ namespace { // aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP // instruction against another. AliasResult aliasGEP(const GEPOperator *V1, uint64_t V1Size, + const MDNode *V1TBAAInfo, const Value *V2, uint64_t V2Size, const MDNode *V2TBAAInfo, const Value *UnderlyingV1, const Value *UnderlyingV2); @@ -543,10 +526,15 @@ namespace { // Register this pass... char BasicAliasAnalysis::ID = 0; -INITIALIZE_AG_PASS(BasicAliasAnalysis, AliasAnalysis, "basicaa", +INITIALIZE_AG_PASS_BEGIN(BasicAliasAnalysis, AliasAnalysis, "basicaa", + "Basic Alias Analysis (stateless AA impl)", + false, true, false) +INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) +INITIALIZE_AG_PASS_END(BasicAliasAnalysis, AliasAnalysis, "basicaa", "Basic Alias Analysis (stateless AA impl)", false, true, false) + ImmutablePass *llvm::createBasicAliasAnalysisPass() { return new BasicAliasAnalysis(); } @@ -643,7 +631,7 @@ BasicAliasAnalysis::getModRefBehavior(const Function *F) { // For intrinsics, we can check the table. if (unsigned iid = F->getIntrinsicID()) { #define GET_INTRINSIC_MODREF_BEHAVIOR -#include "llvm/Intrinsics.gen" +#include "llvm/IR/Intrinsics.gen" #undef GET_INTRINSIC_MODREF_BEHAVIOR } @@ -692,15 +680,14 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS, // pointer were passed to arguments that were neither of these, then it // couldn't be no-capture. if (!(*CI)->getType()->isPointerTy() || - (!CS.paramHasAttr(ArgNo+1, Attribute::NoCapture) && - !CS.paramHasAttr(ArgNo+1, Attribute::ByVal))) + (!CS.doesNotCapture(ArgNo) && !CS.isByValArgument(ArgNo))) continue; // If this is a no-capture pointer argument, see if we can tell that it // is impossible to alias the pointer we're checking. If not, we have to // assume that the call could touch the pointer, even though it doesn't // escape. - if (!isNoAlias(Location(cast(CI)), Loc)) { + if (!isNoAlias(Location(*CI), Location(Object))) { PassedAsArg = true; break; } @@ -710,6 +697,7 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS, return NoModRef; } + const TargetLibraryInfo &TLI = getAnalysis(); ModRefResult Min = ModRef; // Finally, handle specific knowledge of intrinsics. @@ -748,26 +736,6 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS, // We know that memset doesn't load anything. Min = Mod; break; - case Intrinsic::atomic_cmp_swap: - case Intrinsic::atomic_swap: - case Intrinsic::atomic_load_add: - case Intrinsic::atomic_load_sub: - case Intrinsic::atomic_load_and: - case Intrinsic::atomic_load_nand: - case Intrinsic::atomic_load_or: - case Intrinsic::atomic_load_xor: - case Intrinsic::atomic_load_max: - case Intrinsic::atomic_load_min: - case Intrinsic::atomic_load_umax: - case Intrinsic::atomic_load_umin: - if (TD) { - Value *Op1 = II->getArgOperand(0); - uint64_t Op1Size = TD->getTypeStoreSize(Op1->getType()); - MDNode *Tag = II->getMetadata(LLVMContext::MD_tbaa); - if (isNoAlias(Location(Op1, Op1Size, Tag), Loc)) - return NoModRef; - } - break; case Intrinsic::lifetime_start: case Intrinsic::lifetime_end: case Intrinsic::invariant_start: { @@ -812,10 +780,58 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS, } } + // We can bound the aliasing properties of memset_pattern16 just as we can + // for memcpy/memset. This is particularly important because the + // LoopIdiomRecognizer likes to turn loops into calls to memset_pattern16 + // whenever possible. + else if (TLI.has(LibFunc::memset_pattern16) && + CS.getCalledFunction() && + CS.getCalledFunction()->getName() == "memset_pattern16") { + const Function *MS = CS.getCalledFunction(); + FunctionType *MemsetType = MS->getFunctionType(); + if (!MemsetType->isVarArg() && MemsetType->getNumParams() == 3 && + isa(MemsetType->getParamType(0)) && + isa(MemsetType->getParamType(1)) && + isa(MemsetType->getParamType(2))) { + uint64_t Len = UnknownSize; + if (const ConstantInt *LenCI = dyn_cast(CS.getArgument(2))) + Len = LenCI->getZExtValue(); + const Value *Dest = CS.getArgument(0); + const Value *Src = CS.getArgument(1); + // If it can't overlap the source dest, then it doesn't modref the loc. + if (isNoAlias(Location(Dest, Len), Loc)) { + // Always reads 16 bytes of the source. + if (isNoAlias(Location(Src, 16), Loc)) + return NoModRef; + // If it can't overlap the dest, then worst case it reads the loc. + Min = Ref; + // Always reads 16 bytes of the source. + } else if (isNoAlias(Location(Src, 16), Loc)) { + // If it can't overlap the source, then worst case it mutates the loc. + Min = Mod; + } + } + } + // The AliasAnalysis base class has some smarts, lets use them. return ModRefResult(AliasAnalysis::getModRefInfo(CS, Loc) & Min); } +static bool areVarIndicesEqual(SmallVector &Indices1, + SmallVector &Indices2) { + unsigned Size1 = Indices1.size(); + unsigned Size2 = Indices2.size(); + + if (Size1 != Size2) + return false; + + for (unsigned I = 0; I != Size1; ++I) + if (Indices1[I] != Indices2[I]) + return false; + + return true; +} + /// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction /// against another pointer. We know that V1 is a GEP, but we don't know /// anything about V2. UnderlyingV1 is GetUnderlyingObject(GEP1, TD), @@ -823,6 +839,7 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS, /// AliasAnalysis::AliasResult BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, + const MDNode *V1TBAAInfo, const Value *V2, uint64_t V2Size, const MDNode *V2TBAAInfo, const Value *UnderlyingV1, @@ -830,9 +847,41 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, int64_t GEP1BaseOffset; SmallVector GEP1VariableIndices; - // If we have two gep instructions with must-alias'ing base pointers, figure - // out if the indexes to the GEP tell us anything about the derived pointer. + // If we have two gep instructions with must-alias or not-alias'ing base + // pointers, figure out if the indexes to the GEP tell us anything about the + // derived pointer. if (const GEPOperator *GEP2 = dyn_cast(V2)) { + // Check for geps of non-aliasing underlying pointers where the offsets are + // identical. + if (V1Size == V2Size) { + // Do the base pointers alias assuming type and size. + AliasResult PreciseBaseAlias = aliasCheck(UnderlyingV1, V1Size, + V1TBAAInfo, UnderlyingV2, + V2Size, V2TBAAInfo); + if (PreciseBaseAlias == NoAlias) { + // See if the computed offset from the common pointer tells us about the + // relation of the resulting pointer. + int64_t GEP2BaseOffset; + SmallVector GEP2VariableIndices; + const Value *GEP2BasePtr = + DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD); + const Value *GEP1BasePtr = + DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD); + // DecomposeGEPExpression and GetUnderlyingObject should return the + // same result except when DecomposeGEPExpression has no DataLayout. + if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) { + assert(TD == 0 && + "DecomposeGEPExpression and GetUnderlyingObject disagree!"); + return MayAlias; + } + // Same offsets. + if (GEP1BaseOffset == GEP2BaseOffset && + areVarIndicesEqual(GEP1VariableIndices, GEP2VariableIndices)) + return NoAlias; + GEP1VariableIndices.clear(); + } + } + // Do the base pointers alias? AliasResult BaseAlias = aliasCheck(UnderlyingV1, UnknownSize, 0, UnderlyingV2, UnknownSize, 0); @@ -852,9 +901,8 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, const Value *GEP2BasePtr = DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD); - // If DecomposeGEPExpression isn't able to look all the way through the - // addressing operation, we must not have TD and this is too complex for us - // to handle without it. + // DecomposeGEPExpression and GetUnderlyingObject should return the + // same result except when DecomposeGEPExpression has no DataLayout. if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) { assert(TD == 0 && "DecomposeGEPExpression and GetUnderlyingObject disagree!"); @@ -888,9 +936,8 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, const Value *GEP1BasePtr = DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD); - // If DecomposeGEPExpression isn't able to look all the way through the - // addressing operation, we must not have TD and this is too complex for us - // to handle without it. + // DecomposeGEPExpression and GetUnderlyingObject should return the + // same result except when DecomposeGEPExpression has no DataLayout. if (GEP1BasePtr != UnderlyingV1) { assert(TD == 0 && "DecomposeGEPExpression and GetUnderlyingObject disagree!"); @@ -907,53 +954,50 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, if (GEP1BaseOffset == 0 && GEP1VariableIndices.empty()) return MustAlias; - // If there is a difference between the pointers, but the difference is - // less than the size of the associated memory object, then we know - // that the objects are partially overlapping. + // If there is a constant difference between the pointers, but the difference + // is less than the size of the associated memory object, then we know + // that the objects are partially overlapping. If the difference is + // greater, we know they do not overlap. if (GEP1BaseOffset != 0 && GEP1VariableIndices.empty()) { - if (GEP1BaseOffset >= 0 ? - (V2Size != UnknownSize && (uint64_t)GEP1BaseOffset < V2Size) : - (V1Size != UnknownSize && -(uint64_t)GEP1BaseOffset < V1Size && - GEP1BaseOffset != INT64_MIN)) - return PartialAlias; + if (GEP1BaseOffset >= 0) { + if (V2Size != UnknownSize) { + if ((uint64_t)GEP1BaseOffset < V2Size) + return PartialAlias; + return NoAlias; + } + } else { + if (V1Size != UnknownSize) { + if (-(uint64_t)GEP1BaseOffset < V1Size) + return PartialAlias; + return NoAlias; + } + } } - // If we have a known constant offset, see if this offset is larger than the - // access size being queried. If so, and if no variable indices can remove - // pieces of this constant, then we know we have a no-alias. For example, - // &A[100] != &A. - - // In order to handle cases like &A[100][i] where i is an out of range - // subscript, we have to ignore all constant offset pieces that are a multiple - // of a scaled index. Do this by removing constant offsets that are a - // multiple of any of our variable indices. This allows us to transform - // things like &A[i][1] because i has a stride of (e.g.) 8 bytes but the 1 - // provides an offset of 4 bytes (assuming a <= 4 byte access). - for (unsigned i = 0, e = GEP1VariableIndices.size(); - i != e && GEP1BaseOffset;++i) - if (int64_t RemovedOffset = GEP1BaseOffset/GEP1VariableIndices[i].Scale) - GEP1BaseOffset -= RemovedOffset*GEP1VariableIndices[i].Scale; - - // If our known offset is bigger than the access size, we know we don't have - // an alias. - if (GEP1BaseOffset) { - if (GEP1BaseOffset >= 0 ? - (V2Size != UnknownSize && (uint64_t)GEP1BaseOffset >= V2Size) : - (V1Size != UnknownSize && -(uint64_t)GEP1BaseOffset >= V1Size && - GEP1BaseOffset != INT64_MIN)) + // Try to distinguish something like &A[i][1] against &A[42][0]. + // Grab the least significant bit set in any of the scales. + if (!GEP1VariableIndices.empty()) { + uint64_t Modulo = 0; + for (unsigned i = 0, e = GEP1VariableIndices.size(); i != e; ++i) + Modulo |= (uint64_t)GEP1VariableIndices[i].Scale; + Modulo = Modulo ^ (Modulo & (Modulo - 1)); + + // We can compute the difference between the two addresses + // mod Modulo. Check whether that difference guarantees that the + // two locations do not alias. + uint64_t ModOffset = (uint64_t)GEP1BaseOffset & (Modulo - 1); + if (V1Size != UnknownSize && V2Size != UnknownSize && + ModOffset >= V2Size && V1Size <= Modulo - ModOffset) return NoAlias; } - + // Statically, we can see that the base objects are the same, but the // pointers have dynamic offsets which we can't resolve. And none of our // little tricks above worked. // // TODO: Returning PartialAlias instead of MayAlias is a mild hack; the // practical effect of this is protecting TBAA in the case of dynamic - // indices into arrays of unions. An alternative way to solve this would - // be to have clang emit extra metadata for unions and/or union accesses. - // A union-specific solution wouldn't handle the problem for malloc'd - // memory however. + // indices into arrays of unions or malloc'd memory. return PartialAlias; } @@ -1016,13 +1060,24 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize, // on corresponding edges. if (const PHINode *PN2 = dyn_cast(V2)) if (PN2->getParent() == PN->getParent()) { - AliasResult Alias = - aliasCheck(PN->getIncomingValue(0), PNSize, PNTBAAInfo, - PN2->getIncomingValueForBlock(PN->getIncomingBlock(0)), - V2Size, V2TBAAInfo); - if (Alias == MayAlias) - return MayAlias; - for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { + LocPair Locs(Location(PN, PNSize, PNTBAAInfo), + Location(V2, V2Size, V2TBAAInfo)); + if (PN > V2) + std::swap(Locs.first, Locs.second); + // Analyse the PHIs' inputs under the assumption that the PHIs are + // NoAlias. + // If the PHIs are May/MustAlias there must be (recursively) an input + // operand from outside the PHIs' cycle that is MayAlias/MustAlias or + // there must be an operation on the PHIs within the PHIs' value cycle + // that causes a MayAlias. + // Pretend the phis do not alias. + AliasResult Alias = NoAlias; + assert(AliasCache.count(Locs) && + "There must exist an entry for the phi node"); + AliasResult OrigAliasResult = AliasCache[Locs]; + AliasCache[Locs] = NoAlias; + + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { AliasResult ThisAlias = aliasCheck(PN->getIncomingValue(i), PNSize, PNTBAAInfo, PN2->getIncomingValueForBlock(PN->getIncomingBlock(i)), @@ -1031,6 +1086,11 @@ BasicAliasAnalysis::aliasPHI(const PHINode *PN, uint64_t PNSize, if (Alias == MayAlias) break; } + + // Reset if speculation failed. + if (Alias != NoAlias) + AliasCache[Locs] = OrigAliasResult; + return Alias; } @@ -1145,8 +1205,8 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size, // If the size of one access is larger than the entire object on the other // side, then we know such behavior is undefined and can assume no alias. if (TD) - if ((V1Size != UnknownSize && isObjectSmallerThan(O2, V1Size, *TD)) || - (V2Size != UnknownSize && isObjectSmallerThan(O1, V2Size, *TD))) + if ((V1Size != UnknownSize && isObjectSmallerThan(O2, V1Size, *TD, *TLI)) || + (V2Size != UnknownSize && isObjectSmallerThan(O1, V2Size, *TD, *TLI))) return NoAlias; // Check the cache before climbing up use-def chains. This also terminates @@ -1166,15 +1226,17 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size, std::swap(V1, V2); std::swap(V1Size, V2Size); std::swap(O1, O2); + std::swap(V1TBAAInfo, V2TBAAInfo); } if (const GEPOperator *GV1 = dyn_cast(V1)) { - AliasResult Result = aliasGEP(GV1, V1Size, V2, V2Size, V2TBAAInfo, O1, O2); + AliasResult Result = aliasGEP(GV1, V1Size, V1TBAAInfo, V2, V2Size, V2TBAAInfo, O1, O2); if (Result != MayAlias) return AliasCache[Locs] = Result; } if (isa(V2) && !isa(V1)) { std::swap(V1, V2); std::swap(V1Size, V2Size); + std::swap(V1TBAAInfo, V2TBAAInfo); } if (const PHINode *PN = dyn_cast(V1)) { AliasResult Result = aliasPHI(PN, V1Size, V1TBAAInfo, @@ -1185,6 +1247,7 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size, if (isa(V2) && !isa(V1)) { std::swap(V1, V2); std::swap(V1Size, V2Size); + std::swap(V1TBAAInfo, V2TBAAInfo); } if (const SelectInst *S1 = dyn_cast(V1)) { AliasResult Result = aliasSelect(S1, V1Size, V1TBAAInfo, @@ -1196,8 +1259,8 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size, // accesses is accessing the entire object, then the accesses must // overlap in some way. if (TD && O1 == O2) - if ((V1Size != UnknownSize && isObjectSize(O1, V1Size, *TD)) || - (V2Size != UnknownSize && isObjectSize(O2, V2Size, *TD))) + if ((V1Size != UnknownSize && isObjectSize(O1, V1Size, *TD, *TLI)) || + (V2Size != UnknownSize && isObjectSize(O2, V2Size, *TD, *TLI))) return AliasCache[Locs] = PartialAlias; AliasResult Result =