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Diffstat (limited to 'lib/Analysis/MemoryDependenceAnalysis.cpp')
| -rw-r--r-- | lib/Analysis/MemoryDependenceAnalysis.cpp | 1507 |
1 files changed, 1507 insertions, 0 deletions
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp new file mode 100644 index 00000000000..5736c3569dc --- /dev/null +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -0,0 +1,1507 @@ +//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation --*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements an analysis that determines, for a given memory +// operation, what preceding memory operations it depends on. It builds on +// alias analysis information, and tries to provide a lazy, caching interface to +// a common kind of alias information query. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "memdep" +#include "llvm/Analysis/MemoryDependenceAnalysis.h" +#include "llvm/Instructions.h" +#include "llvm/IntrinsicInst.h" +#include "llvm/Function.h" +#include "llvm/LLVMContext.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/MemoryBuiltins.h" +#include "llvm/Analysis/PHITransAddr.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Support/PredIteratorCache.h" +#include "llvm/Support/Debug.h" +#include "llvm/Target/TargetData.h" +using namespace llvm; + +STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses"); +STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses"); +STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses"); + +STATISTIC(NumCacheNonLocalPtr, + "Number of fully cached non-local ptr responses"); +STATISTIC(NumCacheDirtyNonLocalPtr, + "Number of cached, but dirty, non-local ptr responses"); +STATISTIC(NumUncacheNonLocalPtr, + "Number of uncached non-local ptr responses"); +STATISTIC(NumCacheCompleteNonLocalPtr, + "Number of block queries that were completely cached"); + +// Limit for the number of instructions to scan in a block. +// FIXME: Figure out what a sane value is for this. +// (500 is relatively insane.) +static const int BlockScanLimit = 500; + +char MemoryDependenceAnalysis::ID = 0; + +// Register this pass... +INITIALIZE_PASS_BEGIN(MemoryDependenceAnalysis, "memdep", + "Memory Dependence Analysis", false, true) +INITIALIZE_AG_DEPENDENCY(AliasAnalysis) +INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep", + "Memory Dependence Analysis", false, true) + +MemoryDependenceAnalysis::MemoryDependenceAnalysis() +: FunctionPass(ID), PredCache(0) { + initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry()); +} +MemoryDependenceAnalysis::~MemoryDependenceAnalysis() { +} + +/// Clean up memory in between runs +void MemoryDependenceAnalysis::releaseMemory() { + LocalDeps.clear(); + NonLocalDeps.clear(); + NonLocalPointerDeps.clear(); + ReverseLocalDeps.clear(); + ReverseNonLocalDeps.clear(); + ReverseNonLocalPtrDeps.clear(); + PredCache->clear(); +} + + + +/// getAnalysisUsage - Does not modify anything. It uses Alias Analysis. +/// +void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesAll(); + AU.addRequiredTransitive<AliasAnalysis>(); +} + +bool MemoryDependenceAnalysis::runOnFunction(Function &) { + AA = &getAnalysis<AliasAnalysis>(); + TD = getAnalysisIfAvailable<TargetData>(); + DT = getAnalysisIfAvailable<DominatorTree>(); + if (PredCache == 0) + PredCache.reset(new PredIteratorCache()); + return false; +} + +/// RemoveFromReverseMap - This is a helper function that removes Val from +/// 'Inst's set in ReverseMap. If the set becomes empty, remove Inst's entry. +template <typename KeyTy> +static void RemoveFromReverseMap(DenseMap<Instruction*, + SmallPtrSet<KeyTy, 4> > &ReverseMap, + Instruction *Inst, KeyTy Val) { + typename DenseMap<Instruction*, SmallPtrSet<KeyTy, 4> >::iterator + InstIt = ReverseMap.find(Inst); + assert(InstIt != ReverseMap.end() && "Reverse map out of sync?"); + bool Found = InstIt->second.erase(Val); + assert(Found && "Invalid reverse map!"); (void)Found; + if (InstIt->second.empty()) + ReverseMap.erase(InstIt); +} + +/// GetLocation - If the given instruction references a specific memory +/// location, fill in Loc with the details, otherwise set Loc.Ptr to null. +/// Return a ModRefInfo value describing the general behavior of the +/// instruction. +static +AliasAnalysis::ModRefResult GetLocation(const Instruction *Inst, + AliasAnalysis::Location &Loc, + AliasAnalysis *AA) { + if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) { + if (LI->isUnordered()) { + Loc = AA->getLocation(LI); + return AliasAnalysis::Ref; + } else if (LI->getOrdering() == Monotonic) { + Loc = AA->getLocation(LI); + return AliasAnalysis::ModRef; + } + Loc = AliasAnalysis::Location(); + return AliasAnalysis::ModRef; + } + + if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) { + if (SI->isUnordered()) { + Loc = AA->getLocation(SI); + return AliasAnalysis::Mod; + } else if (SI->getOrdering() == Monotonic) { + Loc = AA->getLocation(SI); + return AliasAnalysis::ModRef; + } + Loc = AliasAnalysis::Location(); + return AliasAnalysis::ModRef; + } + + if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) { + Loc = AA->getLocation(V); + return AliasAnalysis::ModRef; + } + + if (const CallInst *CI = isFreeCall(Inst, AA->getTargetLibraryInfo())) { + // calls to free() deallocate the entire structure + Loc = AliasAnalysis::Location(CI->getArgOperand(0)); + return AliasAnalysis::Mod; + } + + if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) + switch (II->getIntrinsicID()) { + case Intrinsic::lifetime_start: + case Intrinsic::lifetime_end: + case Intrinsic::invariant_start: + Loc = AliasAnalysis::Location(II->getArgOperand(1), + cast<ConstantInt>(II->getArgOperand(0)) + ->getZExtValue(), + II->getMetadata(LLVMContext::MD_tbaa)); + // These intrinsics don't really modify the memory, but returning Mod + // will allow them to be handled conservatively. + return AliasAnalysis::Mod; + case Intrinsic::invariant_end: + Loc = AliasAnalysis::Location(II->getArgOperand(2), + cast<ConstantInt>(II->getArgOperand(1)) + ->getZExtValue(), + II->getMetadata(LLVMContext::MD_tbaa)); + // These intrinsics don't really modify the memory, but returning Mod + // will allow them to be handled conservatively. + return AliasAnalysis::Mod; + default: + break; + } + + // Otherwise, just do the coarse-grained thing that always works. + if (Inst->mayWriteToMemory()) + return AliasAnalysis::ModRef; + if (Inst->mayReadFromMemory()) + return AliasAnalysis::Ref; + return AliasAnalysis::NoModRef; +} + +/// getCallSiteDependencyFrom - Private helper for finding the local +/// dependencies of a call site. +MemDepResult MemoryDependenceAnalysis:: +getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall, + BasicBlock::iterator ScanIt, BasicBlock *BB) { + unsigned Limit = BlockScanLimit; + + // Walk backwards through the block, looking for dependencies + while (ScanIt != BB->begin()) { + // Limit the amount of scanning we do so we don't end up with quadratic + // running time on extreme testcases. + --Limit; + if (!Limit) + return MemDepResult::getUnknown(); + + Instruction *Inst = --ScanIt; + + // If this inst is a memory op, get the pointer it accessed + AliasAnalysis::Location Loc; + AliasAnalysis::ModRefResult MR = GetLocation(Inst, Loc, AA); + if (Loc.Ptr) { + // A simple instruction. + if (AA->getModRefInfo(CS, Loc) != AliasAnalysis::NoModRef) + return MemDepResult::getClobber(Inst); + continue; + } + + if (CallSite InstCS = cast<Value>(Inst)) { + // Debug intrinsics don't cause dependences. + if (isa<DbgInfoIntrinsic>(Inst)) continue; + // If these two calls do not interfere, look past it. + switch (AA->getModRefInfo(CS, InstCS)) { + case AliasAnalysis::NoModRef: + // If the two calls are the same, return InstCS as a Def, so that + // CS can be found redundant and eliminated. + if (isReadOnlyCall && !(MR & AliasAnalysis::Mod) && + CS.getInstruction()->isIdenticalToWhenDefined(Inst)) + return MemDepResult::getDef(Inst); + + // Otherwise if the two calls don't interact (e.g. InstCS is readnone) + // keep scanning. + continue; + default: + return MemDepResult::getClobber(Inst); + } + } + + // If we could not obtain a pointer for the instruction and the instruction + // touches memory then assume that this is a dependency. + if (MR != AliasAnalysis::NoModRef) + return MemDepResult::getClobber(Inst); + } + + // No dependence found. If this is the entry block of the function, it is + // unknown, otherwise it is non-local. + if (BB != &BB->getParent()->getEntryBlock()) + return MemDepResult::getNonLocal(); + return MemDepResult::getNonFuncLocal(); +} + +/// isLoadLoadClobberIfExtendedToFullWidth - Return true if LI is a load that +/// would fully overlap MemLoc if done as a wider legal integer load. +/// +/// MemLocBase, MemLocOffset are lazily computed here the first time the +/// base/offs of memloc is needed. +static bool +isLoadLoadClobberIfExtendedToFullWidth(const AliasAnalysis::Location &MemLoc, + const Value *&MemLocBase, + int64_t &MemLocOffs, + const LoadInst *LI, + const TargetData *TD) { + // If we have no target data, we can't do this. + if (TD == 0) return false; + + // If we haven't already computed the base/offset of MemLoc, do so now. + if (MemLocBase == 0) + MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, *TD); + + unsigned Size = MemoryDependenceAnalysis:: + getLoadLoadClobberFullWidthSize(MemLocBase, MemLocOffs, MemLoc.Size, + LI, *TD); + return Size != 0; +} + +/// getLoadLoadClobberFullWidthSize - This is a little bit of analysis that +/// looks at a memory location for a load (specified by MemLocBase, Offs, +/// and Size) and compares it against a load. If the specified load could +/// be safely widened to a larger integer load that is 1) still efficient, +/// 2) safe for the target, and 3) would provide the specified memory +/// location value, then this function returns the size in bytes of the +/// load width to use. If not, this returns zero. +unsigned MemoryDependenceAnalysis:: +getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs, + unsigned MemLocSize, const LoadInst *LI, + const TargetData &TD) { + // We can only extend simple integer loads. + if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0; + + // Get the base of this load. + int64_t LIOffs = 0; + const Value *LIBase = + GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, TD); + + // If the two pointers are not based on the same pointer, we can't tell that + // they are related. + if (LIBase != MemLocBase) return 0; + + // Okay, the two values are based on the same pointer, but returned as + // no-alias. This happens when we have things like two byte loads at "P+1" + // and "P+3". Check to see if increasing the size of the "LI" load up to its + // alignment (or the largest native integer type) will allow us to load all + // the bits required by MemLoc. + + // If MemLoc is before LI, then no widening of LI will help us out. + if (MemLocOffs < LIOffs) return 0; + + // Get the alignment of the load in bytes. We assume that it is safe to load + // any legal integer up to this size without a problem. For example, if we're + // looking at an i8 load on x86-32 that is known 1024 byte aligned, we can + // widen it up to an i32 load. If it is known 2-byte aligned, we can widen it + // to i16. + unsigned LoadAlign = LI->getAlignment(); + + int64_t MemLocEnd = MemLocOffs+MemLocSize; + + // If no amount of rounding up will let MemLoc fit into LI, then bail out. + if (LIOffs+LoadAlign < MemLocEnd) return 0; + + // This is the size of the load to try. Start with the next larger power of + // two. + unsigned NewLoadByteSize = LI->getType()->getPrimitiveSizeInBits()/8U; + NewLoadByteSize = NextPowerOf2(NewLoadByteSize); + + while (1) { + // If this load size is bigger than our known alignment or would not fit + // into a native integer register, then we fail. + if (NewLoadByteSize > LoadAlign || + !TD.fitsInLegalInteger(NewLoadByteSize*8)) + return 0; + + if (LIOffs+NewLoadByteSize > MemLocEnd && + LI->getParent()->getParent()->hasFnAttr(Attribute::AddressSafety)) { + // We will be reading past the location accessed by the original program. + // While this is safe in a regular build, Address Safety analysis tools + // may start reporting false warnings. So, don't do widening. + return 0; + } + + // If a load of this width would include all of MemLoc, then we succeed. + if (LIOffs+NewLoadByteSize >= MemLocEnd) + return NewLoadByteSize; + + NewLoadByteSize <<= 1; + } +} + +/// getPointerDependencyFrom - Return the instruction on which a memory +/// location depends. If isLoad is true, this routine ignores may-aliases with +/// read-only operations. If isLoad is false, this routine ignores may-aliases +/// with reads from read-only locations. +MemDepResult MemoryDependenceAnalysis:: +getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad, + BasicBlock::iterator ScanIt, BasicBlock *BB) { + + const Value *MemLocBase = 0; + int64_t MemLocOffset = 0; + + unsigned Limit = BlockScanLimit; + + // Walk backwards through the basic block, looking for dependencies. + while (ScanIt != BB->begin()) { + // Limit the amount of scanning we do so we don't end up with quadratic + // running time on extreme testcases. + --Limit; + if (!Limit) + return MemDepResult::getUnknown(); + + Instruction *Inst = --ScanIt; + + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { + // Debug intrinsics don't (and can't) cause dependences. + if (isa<DbgInfoIntrinsic>(II)) continue; + + // If we reach a lifetime begin or end marker, then the query ends here + // because the value is undefined. + if (II->getIntrinsicID() == Intrinsic::lifetime_start) { + // FIXME: This only considers queries directly on the invariant-tagged + // pointer, not on query pointers that are indexed off of them. It'd + // be nice to handle that at some point (the right approach is to use + // GetPointerBaseWithConstantOffset). + if (AA->isMustAlias(AliasAnalysis::Location(II->getArgOperand(1)), + MemLoc)) + return MemDepResult::getDef(II); + continue; + } + } + + // Values depend on loads if the pointers are must aliased. This means that + // a load depends on another must aliased load from the same value. + if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) { + // Atomic loads have complications involved. + // FIXME: This is overly conservative. + if (!LI->isUnordered()) + return MemDepResult::getClobber(LI); + + AliasAnalysis::Location LoadLoc = AA->getLocation(LI); + + // If we found a pointer, check if it could be the same as our pointer. + AliasAnalysis::AliasResult R = AA->alias(LoadLoc, MemLoc); + + if (isLoad) { + if (R == AliasAnalysis::NoAlias) { + // If this is an over-aligned integer load (for example, + // "load i8* %P, align 4") see if it would obviously overlap with the + // queried location if widened to a larger load (e.g. if the queried + // location is 1 byte at P+1). If so, return it as a load/load + // clobber result, allowing the client to decide to widen the load if + // it wants to. + if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) + if (LI->getAlignment()*8 > ITy->getPrimitiveSizeInBits() && + isLoadLoadClobberIfExtendedToFullWidth(MemLoc, MemLocBase, + MemLocOffset, LI, TD)) + return MemDepResult::getClobber(Inst); + + continue; + } + + // Must aliased loads are defs of each other. + if (R == AliasAnalysis::MustAlias) + return MemDepResult::getDef(Inst); + +#if 0 // FIXME: Temporarily disabled. GVN is cleverly rewriting loads + // in terms of clobbering loads, but since it does this by looking + // at the clobbering load directly, it doesn't know about any + // phi translation that may have happened along the way. + + // If we have a partial alias, then return this as a clobber for the + // client to handle. + if (R == AliasAnalysis::PartialAlias) + return MemDepResult::getClobber(Inst); +#endif + + // Random may-alias loads don't depend on each other without a + // dependence. + continue; + } + + // Stores don't depend on other no-aliased accesses. + if (R == AliasAnalysis::NoAlias) + continue; + + // Stores don't alias loads from read-only memory. + if (AA->pointsToConstantMemory(LoadLoc)) + continue; + + // Stores depend on may/must aliased loads. + return MemDepResult::getDef(Inst); + } + + if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { + // Atomic stores have complications involved. + // FIXME: This is overly conservative. + if (!SI->isUnordered()) + return MemDepResult::getClobber(SI); + + // If alias analysis can tell that this store is guaranteed to not modify + // the query pointer, ignore it. Use getModRefInfo to handle cases where + // the query pointer points to constant memory etc. + if (AA->getModRefInfo(SI, MemLoc) == AliasAnalysis::NoModRef) + continue; + + // Ok, this store might clobber the query pointer. Check to see if it is + // a must alias: in this case, we want to return this as a def. + AliasAnalysis::Location StoreLoc = AA->getLocation(SI); + + // If we found a pointer, check if it could be the same as our pointer. + AliasAnalysis::AliasResult R = AA->alias(StoreLoc, MemLoc); + + if (R == AliasAnalysis::NoAlias) + continue; + if (R == AliasAnalysis::MustAlias) + return MemDepResult::getDef(Inst); + return MemDepResult::getClobber(Inst); + } + + // If this is an allocation, and if we know that the accessed pointer is to + // the allocation, return Def. This means that there is no dependence and + // the access can be optimized based on that. For example, a load could + // turn into undef. + // Note: Only determine this to be a malloc if Inst is the malloc call, not + // a subsequent bitcast of the malloc call result. There can be stores to + // the malloced memory between the malloc call and its bitcast uses, and we + // need to continue scanning until the malloc call. + const TargetLibraryInfo *TLI = AA->getTargetLibraryInfo(); + if (isa<AllocaInst>(Inst) || isNoAliasFn(Inst, TLI)) { + const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, TD); + + if (AccessPtr == Inst || AA->isMustAlias(Inst, AccessPtr)) + return MemDepResult::getDef(Inst); + // Be conservative if the accessed pointer may alias the allocation. + if (AA->alias(Inst, AccessPtr) != AliasAnalysis::NoAlias) + return MemDepResult::getClobber(Inst); + // If the allocation is not aliased and does not read memory (like + // strdup), it is safe to ignore. + if (isa<AllocaInst>(Inst) || + isMallocLikeFn(Inst, TLI) || isCallocLikeFn(Inst, TLI)) + continue; + } + + // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer. + AliasAnalysis::ModRefResult MR = AA->getModRefInfo(Inst, MemLoc); + // If necessary, perform additional analysis. + if (MR == AliasAnalysis::ModRef) + MR = AA->callCapturesBefore(Inst, MemLoc, DT); + switch (MR) { + case AliasAnalysis::NoModRef: + // If the call has no effect on the queried pointer, just ignore it. + continue; + case AliasAnalysis::Mod: + return MemDepResult::getClobber(Inst); + case AliasAnalysis::Ref: + // If the call is known to never store to the pointer, and if this is a + // load query, we can safely ignore it (scan past it). + if (isLoad) + continue; + default: + // Otherwise, there is a potential dependence. Return a clobber. + return MemDepResult::getClobber(Inst); + } + } + + // No dependence found. If this is the entry block of the function, it is + // unknown, otherwise it is non-local. + if (BB != &BB->getParent()->getEntryBlock()) + return MemDepResult::getNonLocal(); + return MemDepResult::getNonFuncLocal(); +} + +/// getDependency - Return the instruction on which a memory operation +/// depends. +MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) { + Instruction *ScanPos = QueryInst; + + // Check for a cached result + MemDepResult &LocalCache = LocalDeps[QueryInst]; + + // If the cached entry is non-dirty, just return it. Note that this depends + // on MemDepResult's default constructing to 'dirty'. + if (!LocalCache.isDirty()) + return LocalCache; + + // Otherwise, if we have a dirty entry, we know we can start the scan at that + // instruction, which may save us some work. + if (Instruction *Inst = LocalCache.getInst()) { + ScanPos = Inst; + + RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst); + } + + BasicBlock *QueryParent = QueryInst->getParent(); + + // Do the scan. + if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) { + // No dependence found. If this is the entry block of the function, it is + // unknown, otherwise it is non-local. + if (QueryParent != &QueryParent->getParent()->getEntryBlock()) + LocalCache = MemDepResult::getNonLocal(); + else + LocalCache = MemDepResult::getNonFuncLocal(); + } else { + AliasAnalysis::Location MemLoc; + AliasAnalysis::ModRefResult MR = GetLocation(QueryInst, MemLoc, AA); + if (MemLoc.Ptr) { + // If we can do a pointer scan, make it happen. + bool isLoad = !(MR & AliasAnalysis::Mod); + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst)) + isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_start; + + LocalCache = getPointerDependencyFrom(MemLoc, isLoad, ScanPos, + QueryParent); + } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) { + CallSite QueryCS(QueryInst); + bool isReadOnly = AA->onlyReadsMemory(QueryCS); + LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos, + QueryParent); + } else + // Non-memory instruction. + LocalCache = MemDepResult::getUnknown(); + } + + // Remember the result! + if (Instruction *I = LocalCache.getInst()) + ReverseLocalDeps[I].insert(QueryInst); + + return LocalCache; +} + +#ifndef NDEBUG +/// AssertSorted - This method is used when -debug is specified to verify that +/// cache arrays are properly kept sorted. +static void AssertSorted(MemoryDependenceAnalysis::NonLocalDepInfo &Cache, + int Count = -1) { + if (Count == -1) Count = Cache.size(); + if (Count == 0) return; + + for (unsigned i = 1; i != unsigned(Count); ++i) + assert(!(Cache[i] < Cache[i-1]) && "Cache isn't sorted!"); +} +#endif + +/// getNonLocalCallDependency - Perform a full dependency query for the +/// specified call, returning the set of blocks that the value is +/// potentially live across. The returned set of results will include a +/// "NonLocal" result for all blocks where the value is live across. +/// +/// This method assumes the instruction returns a "NonLocal" dependency +/// within its own block. +/// +/// This returns a reference to an internal data structure that may be +/// invalidated on the next non-local query or when an instruction is +/// removed. Clients must copy this data if they want it around longer than +/// that. +const MemoryDependenceAnalysis::NonLocalDepInfo & +MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) { + assert(getDependency(QueryCS.getInstruction()).isNonLocal() && + "getNonLocalCallDependency should only be used on calls with non-local deps!"); + PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()]; + NonLocalDepInfo &Cache = CacheP.first; + + /// DirtyBlocks - This is the set of blocks that need to be recomputed. In + /// the cached case, this can happen due to instructions being deleted etc. In + /// the uncached case, this starts out as the set of predecessors we care + /// about. + SmallVector<BasicBlock*, 32> DirtyBlocks; + + if (!Cache.empty()) { + // Okay, we have a cache entry. If we know it is not dirty, just return it + // with no computation. + if (!CacheP.second) { + ++NumCacheNonLocal; + return Cache; + } + + // If we already have a partially computed set of results, scan them to + // determine what is dirty, seeding our initial DirtyBlocks worklist. + for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end(); + I != E; ++I) + if (I->getResult().isDirty()) + DirtyBlocks.push_back(I->getBB()); + + // Sort the cache so that we can do fast binary search lookups below. + std::sort(Cache.begin(), Cache.end()); + + ++NumCacheDirtyNonLocal; + //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: " + // << Cache.size() << " cached: " << *QueryInst; + } else { + // Seed DirtyBlocks with each of the preds of QueryInst's block. + BasicBlock *QueryBB = QueryCS.getInstruction()->getParent(); + for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI) + DirtyBlocks.push_back(*PI); + ++NumUncacheNonLocal; + } + + // isReadonlyCall - If this is a read-only call, we can be more aggressive. + bool isReadonlyCall = AA->onlyReadsMemory(QueryCS); + + SmallPtrSet<BasicBlock*, 64> Visited; + + unsigned NumSortedEntries = Cache.size(); + DEBUG(AssertSorted(Cache)); + + // Iterate while we still have blocks to update. + while (!DirtyBlocks.empty()) { + BasicBlock *DirtyBB = DirtyBlocks.back(); + DirtyBlocks.pop_back(); + + // Already processed this block? + if (!Visited.insert(DirtyBB)) + continue; + + // Do a binary search to see if we already have an entry for this block in + // the cache set. If so, find it. + DEBUG(AssertSorted(Cache, NumSortedEntries)); + NonLocalDepInfo::iterator Entry = + std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries, + NonLocalDepEntry(DirtyBB)); + if (Entry != Cache.begin() && prior(Entry)->getBB() == DirtyBB) + --Entry; + + NonLocalDepEntry *ExistingResult = 0; + if (Entry != Cache.begin()+NumSortedEntries && + Entry->getBB() == DirtyBB) { + // If we already have an entry, and if it isn't already dirty, the block + // is done. + if (!Entry->getResult().isDirty()) + continue; + + // Otherwise, remember this slot so we can update the value. + ExistingResult = &*Entry; + } + + // If the dirty entry has a pointer, start scanning from it so we don't have + // to rescan the entire block. + BasicBlock::iterator ScanPos = DirtyBB->end(); + if (ExistingResult) { + if (Instruction *Inst = ExistingResult->getResult().getInst()) { + ScanPos = Inst; + // We're removing QueryInst's use of Inst. + RemoveFromReverseMap(ReverseNonLocalDeps, Inst, + QueryCS.getInstruction()); + } + } + + // Find out if this block has a local dependency for QueryInst. + MemDepResult Dep; + + if (ScanPos != DirtyBB->begin()) { + Dep = getCallSiteDependencyFrom(QueryCS, isReadonlyCall,ScanPos, DirtyBB); + } else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) { + // No dependence found. If this is the entry block of the function, it is + // a clobber, otherwise it is unknown. + Dep = MemDepResult::getNonLocal(); + } else { + Dep = MemDepResult::getNonFuncLocal(); + } + + // If we had a dirty entry for the block, update it. Otherwise, just add + // a new entry. + if (ExistingResult) + ExistingResult->setResult(Dep); + else + Cache.push_back(NonLocalDepEntry(DirtyBB, Dep)); + + // If the block has a dependency (i.e. it isn't completely transparent to + // the value), remember the association! + if (!Dep.isNonLocal()) { + // Keep the ReverseNonLocalDeps map up to date so we can efficiently + // update this when we remove instructions. + if (Instruction *Inst = Dep.getInst()) + ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction()); + } else { + + // If the block *is* completely transparent to the load, we need to check + // the predecessors of this block. Add them to our worklist. + for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI) + DirtyBlocks.push_back(*PI); + } + } + + return Cache; +} + +/// getNonLocalPointerDependency - Perform a full dependency query for an +/// access to the specified (non-volatile) memory location, returning the +/// set of instructions that either define or clobber the value. +/// +/// This method assumes the pointer has a "NonLocal" dependency within its +/// own block. +/// +void MemoryDependenceAnalysis:: +getNonLocalPointerDependency(const AliasAnalysis::Location &Loc, bool isLoad, + BasicBlock *FromBB, + SmallVectorImpl<NonLocalDepResult> &Result) { + assert(Loc.Ptr->getType()->isPointerTy() && + "Can't get pointer deps of a non-pointer!"); + Result.clear(); + + PHITransAddr Address(const_cast<Value *>(Loc.Ptr), TD); + + // This is the set of blocks we've inspected, and the pointer we consider in + // each block. Because of critical edges, we currently bail out if querying + // a block with multiple different pointers. This can happen during PHI + // translation. + DenseMap<BasicBlock*, Value*> Visited; + if (!getNonLocalPointerDepFromBB(Address, Loc, isLoad, FromBB, + Result, Visited, true)) + return; + Result.clear(); + Result.push_back(NonLocalDepResult(FromBB, + MemDepResult::getUnknown(), + const_cast<Value *>(Loc.Ptr))); +} + +/// GetNonLocalInfoForBlock - Compute the memdep value for BB with +/// Pointer/PointeeSize using either cached information in Cache or by doing a +/// lookup (which may use dirty cache info if available). If we do a lookup, +/// add the result to the cache. +MemDepResult MemoryDependenceAnalysis:: +GetNonLocalInfoForBlock(const AliasAnalysis::Location &Loc, + bool isLoad, BasicBlock *BB, + NonLocalDepInfo *Cache, unsigned NumSortedEntries) { + + // Do a binary search to see if we already have an entry for this block in + // the cache set. If so, find it. + NonLocalDepInfo::iterator Entry = + std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries, + NonLocalDepEntry(BB)); + if (Entry != Cache->begin() && (Entry-1)->getBB() == BB) + --Entry; + + NonLocalDepEntry *ExistingResult = 0; + if (Entry != Cache->begin()+NumSortedEntries && Entry->getBB() == BB) + ExistingResult = &*Entry; + + // If we have a cached entry, and it is non-dirty, use it as the value for + // this dependency. + if (ExistingResult && !ExistingResult->getResult().isDirty()) { + ++NumCacheNonLocalPtr; + return ExistingResult->getResult(); + } + + // Otherwise, we have to scan for the value. If we have a dirty cache + // entry, start scanning from its position, otherwise we scan from the end + // of the block. + BasicBlock::iterator ScanPos = BB->end(); + if (ExistingResult && ExistingResult->getResult().getInst()) { + assert(ExistingResult->getResult().getInst()->getParent() == BB && + "Instruction invalidated?"); + ++NumCacheDirtyNonLocalPtr; + ScanPos = ExistingResult->getResult().getInst(); + + // Eliminating the dirty entry from 'Cache', so update the reverse info. + ValueIsLoadPair CacheKey(Loc.Ptr, isLoad); + RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, CacheKey); + } else { + ++NumUncacheNonLocalPtr; + } + + // Scan the block for the dependency. + MemDepResult Dep = getPointerDependencyFrom(Loc, isLoad, ScanPos, BB); + + // If we had a dirty entry for the block, update it. Otherwise, just add + // a new entry. + if (ExistingResult) + ExistingResult->setResult(Dep); + else + Cache->push_back(NonLocalDepEntry(BB, Dep)); + + // If the block has a dependency (i.e. it isn't completely transparent to + // the value), remember the reverse association because we just added it + // to Cache! + if (!Dep.isDef() && !Dep.isClobber()) + return Dep; + + // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently + // update MemDep when we remove instructions. + Instruction *Inst = Dep.getInst(); + assert(Inst && "Didn't depend on anything?"); + ValueIsLoadPair CacheKey(Loc.Ptr, isLoad); + ReverseNonLocalPtrDeps[Inst].insert(CacheKey); + return Dep; +} + +/// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain +/// number of elements in the array that are already properly ordered. This is +/// optimized for the case when only a few entries are added. +static void +SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache, + unsigned NumSortedEntries) { + switch (Cache.size() - NumSortedEntries) { + case 0: + // done, no new entries. + break; + case 2: { + // Two new entries, insert the last one into place. + NonLocalDepEntry Val = Cache.back(); + Cache.pop_back(); + MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry = + std::upper_bound(Cache.begin(), Cache.end()-1, Val); + Cache.insert(Entry, Val); + // FALL THROUGH. + } + case 1: + // One new entry, Just insert the new value at the appropriate position. + if (Cache.size() != 1) { + NonLocalDepEntry Val = Cache.back(); + Cache.pop_back(); + MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry = + std::upper_bound(Cache.begin(), Cache.end(), Val); + Cache.insert(Entry, Val); + } + break; + default: + // Added many values, do a full scale sort. + std::sort(Cache.begin(), Cache.end()); + break; + } +} + +/// getNonLocalPointerDepFromBB - Perform a dependency query based on +/// pointer/pointeesize starting at the end of StartBB. Add any clobber/def +/// results to the results vector and keep track of which blocks are visited in +/// 'Visited'. +/// +/// This has special behavior for the first block queries (when SkipFirstBlock +/// is true). In this special case, it ignores the contents of the specified +/// block and starts returning dependence info for its predecessors. +/// +/// This function returns false on success, or true to indicate that it could +/// not compute dependence information for some reason. This should be treated +/// as a clobber dependence on the first instruction in the predecessor block. +bool MemoryDependenceAnalysis:: +getNonLocalPointerDepFromBB(const PHITransAddr &Pointer, + const AliasAnalysis::Location &Loc, + bool isLoad, BasicBlock *StartBB, + SmallVectorImpl<NonLocalDepResult> &Result, + DenseMap<BasicBlock*, Value*> &Visited, + bool SkipFirstBlock) { + + // Look up the cached info for Pointer. + ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad); + + // Set up a temporary NLPI value. If the map doesn't yet have an entry for + // CacheKey, this value will be inserted as the associated value. Otherwise, + // it'll be ignored, and we'll have to check to see if the cached size and + // tbaa tag are consistent with the current query. + NonLocalPointerInfo InitialNLPI; + InitialNLPI.Size = Loc.Size; + InitialNLPI.TBAATag = Loc.TBAATag; + + // Get the NLPI for CacheKey, inserting one into the map if it doesn't + // already have one. + std::pair<CachedNonLocalPointerInfo::iterator, bool> Pair = + NonLocalPointerDeps.insert(std::make_pair(CacheKey, InitialNLPI)); + NonLocalPointerInfo *CacheInfo = &Pair.first->second; + + // If we already have a cache entry for this CacheKey, we may need to do some + // work to reconcile the cache entry and the current query. + if (!Pair.second) { + if (CacheInfo->Size < Loc.Size) { + // The query's Size is greater than the cached one. Throw out the + // cached data and proceed with the query at the greater size. + CacheInfo->Pair = BBSkipFirstBlockPair(); + CacheInfo->Size = Loc.Size; + for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(), + DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI) + if (Instruction *Inst = DI->getResult().getInst()) + RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey); + CacheInfo->NonLocalDeps.clear(); + } else if (CacheInfo->Size > Loc.Size) { + // This query's Size is less than the cached one. Conservatively restart + // the query using the greater size. + return getNonLocalPointerDepFromBB(Pointer, + Loc.getWithNewSize(CacheInfo->Size), + isLoad, StartBB, Result, Visited, + SkipFirstBlock); + } + + // If the query's TBAATag is inconsistent with the cached one, + // conservatively throw out the cached data and restart the query with + // no tag if needed. + if (CacheInfo->TBAATag != Loc.TBAATag) { + if (CacheInfo->TBAATag) { + CacheInfo->Pair = BBSkipFirstBlockPair(); + CacheInfo->TBAATag = 0; + for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(), + DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI) + if (Instruction *Inst = DI->getResult().getInst()) + RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey); + CacheInfo->NonLocalDeps.clear(); + } + if (Loc.TBAATag) + return getNonLocalPointerDepFromBB(Pointer, Loc.getWithoutTBAATag(), + isLoad, StartBB, Result, Visited, + SkipFirstBlock); + } + } + + NonLocalDepInfo *Cache = &CacheInfo->NonLocalDeps; + + // If we have valid cached information for exactly the block we are + // investigating, just return it with no recomputation. + if (CacheInfo->Pair == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) { + // We have a fully cached result for this query then we can just return the + // cached results and populate the visited set. However, we have to verify + // that we don't already have conflicting results for these blocks. Check + // to ensure that if a block in the results set is in the visited set that + // it was for the same pointer query. + if (!Visited.empty()) { + for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end(); + I != E; ++I) { + DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->getBB()); + if (VI == Visited.end() || VI->second == Pointer.getAddr()) + continue; + + // We have a pointer mismatch in a block. Just return clobber, saying + // that something was clobbered in this result. We could also do a + // non-fully cached query, but there is little point in doing this. + return true; + } + } + + Value *Addr = Pointer.getAddr(); + for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end(); + I != E; ++I) { + Visited.insert(std::make_pair(I->getBB(), Addr)); + if (!I->getResult().isNonLocal()) + Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr)); + } + ++NumCacheCompleteNonLocalPtr; + return false; + } + + // Otherwise, either this is a new block, a block with an invalid cache + // pointer or one that we're about to invalidate by putting more info into it + // than its valid cache info. If empty, the result will be valid cache info, + // otherwise it isn't. + if (Cache->empty()) + CacheInfo->Pair = BBSkipFirstBlockPair(StartBB, SkipFirstBlock); + else + CacheInfo->Pair = BBSkipFirstBlockPair(); + + SmallVector<BasicBlock*, 32> Worklist; + Worklist.push_back(StartBB); + + // PredList used inside loop. + SmallVector<std::pair<BasicBlock*, PHITransAddr>, 16> PredList; + + // Keep track of the entries that we know are sorted. Previously cached + // entries will all be sorted. The entries we add we only sort on demand (we + // don't insert every element into its sorted position). We know that we + // won't get any reuse from currently inserted values, because we don't + // revisit blocks after we insert info for them. + unsigned NumSortedEntries = Cache->size(); + DEBUG(AssertSorted(*Cache)); + + while (!Worklist.empty()) { + BasicBlock *BB = Worklist.pop_back_val(); + + // Skip the first block if we have it. + if (!SkipFirstBlock) { + // Analyze the dependency of *Pointer in FromBB. See if we already have + // been here. + assert(Visited.count(BB) && "Should check 'visited' before adding to WL"); + + // Get the dependency info for Pointer in BB. If we have cached + // information, we will use it, otherwise we compute it. + DEBUG(AssertSorted(*Cache, NumSortedEntries)); + MemDepResult Dep = GetNonLocalInfoForBlock(Loc, isLoad, BB, Cache, + NumSortedEntries); + + // If we got a Def or Clobber, add this to the list of results. + if (!Dep.isNonLocal()) { + Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr())); + continue; + } + } + + // If 'Pointer' is an instruction defined in this block, then we need to do + // phi translation to change it into a value live in the predecessor block. + // If not, we just add the predecessors to the worklist and scan them with + // the same Pointer. + if (!Pointer.NeedsPHITranslationFromBlock(BB)) { + SkipFirstBlock = false; + SmallVector<BasicBlock*, 16> NewBlocks; + for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { + // Verify that we haven't looked at this block yet. + std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool> + InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr())); + if (InsertRes.second) { + // First time we've looked at *PI. + NewBlocks.push_back(*PI); + continue; + } + + // If we have seen this block before, but it was with a different + // pointer then we have a phi translation failure and we have to treat + // this as a clobber. + if (InsertRes.first->second != Pointer.getAddr()) { + // Make sure to clean up the Visited map before continuing on to + // PredTranslationFailure. + for (unsigned i = 0; i < NewBlocks.size(); i++) + Visited.erase(NewBlocks[i]); + goto PredTranslationFailure; + } + } + Worklist.append(NewBlocks.begin(), NewBlocks.end()); + continue; + } + + // We do need to do phi translation, if we know ahead of time we can't phi + // translate this value, don't even try. + if (!Pointer.IsPotentiallyPHITranslatable()) + goto PredTranslationFailure; + + // We may have added values to the cache list before this PHI translation. + // If so, we haven't done anything to ensure that the cache remains sorted. + // Sort it now (if needed) so that recursive invocations of + // getNonLocalPointerDepFromBB and other routines that could reuse the cache + // value will only see properly sorted cache arrays. + if (Cache && NumSortedEntries != Cache->size()) { + SortNonLocalDepInfoCache(*Cache, NumSortedEntries); + NumSortedEntries = Cache->size(); + } + Cache = 0; + + PredList.clear(); + for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { + BasicBlock *Pred = *PI; + PredList.push_back(std::make_pair(Pred, Pointer)); + + // Get the PHI translated pointer in this predecessor. This can fail if + // not translatable, in which case the getAddr() returns null. + PHITransAddr &PredPointer = PredList.back().second; + PredPointer.PHITranslateValue(BB, Pred, 0); + + Value *PredPtrVal = PredPointer.getAddr(); + + // Check to see if we have already visited this pred block with another + // pointer. If so, we can't do this lookup. This failure can occur + // with PHI translation when a critical edge exists and the PHI node in + // the successor translates to a pointer value different than the + // pointer the block was first analyzed with. + std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool> + InsertRes = Visited.insert(std::make_pair(Pred, PredPtrVal)); + + if (!InsertRes.second) { + // We found the pred; take it off the list of preds to visit. + PredList.pop_back(); + + // If the predecessor was visited with PredPtr, then we already did + // the analysis and can ignore it. + if (InsertRes.first->second == PredPtrVal) + continue; + + // Otherwise, the block was previously analyzed with a different + // pointer. We can't represent the result of this case, so we just + // treat this as a phi translation failure. + + // Make sure to clean up the Visited map before continuing on to + // PredTranslationFailure. + for (unsigned i = 0; i < PredList.size(); i++) + Visited.erase(PredList[i].first); + + goto PredTranslationFailure; + } + } + + // Actually process results here; this need to be a separate loop to avoid + // calling getNonLocalPointerDepFromBB for blocks we don't want to return + // any results for. (getNonLocalPointerDepFromBB will modify our + // datastructures in ways the code after the PredTranslationFailure label + // doesn't expect.) + for (unsigned i = 0; i < PredList.size(); i++) { + BasicBlock *Pred = PredList[i].first; + PHITransAddr &PredPointer = PredList[i].second; + Value *PredPtrVal = PredPointer.getAddr(); + + bool CanTranslate = true; + // If PHI translation was unable to find an available pointer in this + // predecessor, then we have to assume that the pointer is clobbered in + // that predecessor. We can still do PRE of the load, which would insert + // a computation of the pointer in this predecessor. + if (PredPtrVal == 0) + CanTranslate = false; + + // FIXME: it is entirely possible that PHI translating will end up with + // the same value. Consider PHI translating something like: + // X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need* + // to recurse here, pedantically speaking. + + // If getNonLocalPointerDepFromBB fails here, that means the cached + // result conflicted with the Visited list; we have to conservatively + // assume it is unknown, but this also does not block PRE of the load. + if (!CanTranslate || + getNonLocalPointerDepFromBB(PredPointer, + Loc.getWithNewPtr(PredPtrVal), + isLoad, Pred, + Result, Visited)) { + // Add the entry to the Result list. + NonLocalDepResult Entry(Pred, MemDepResult::getUnknown(), PredPtrVal); + Result.push_back(Entry); + + // Since we had a phi translation failure, the cache for CacheKey won't + // include all of the entries that we need to immediately satisfy future + // queries. Mark this in NonLocalPointerDeps by setting the + // BBSkipFirstBlockPair pointer to null. This requires reuse of the + // cached value to do more work but not miss the phi trans failure. + NonLocalPointerInfo &NLPI = NonLocalPointerDeps[CacheKey]; + NLPI.Pair = BBSkipFirstBlockPair(); + continue; + } + } + + // Refresh the CacheInfo/Cache pointer so that it isn't invalidated. + CacheInfo = &NonLocalPointerDeps[CacheKey]; + Cache = &CacheInfo->NonLocalDeps; + NumSortedEntries = Cache->size(); + + // Since we did phi translation, the "Cache" set won't contain all of the + // results for the query. This is ok (we can still use it to accelerate + // specific block queries) but we can't do the fastpath "return all + // results from the set" Clear out the indicator for this. + CacheInfo->Pair = BBSkipFirstBlockPair(); + SkipFirstBlock = false; + continue; + + PredTranslationFailure: + // The following code is "failure"; we can't produce a sane translation + // for the given block. It assumes that we haven't modified any of + // our datastructures while processing the current block. + + if (Cache == 0) { + // Refresh the CacheInfo/Cache pointer if it got invalidated. + CacheInfo = &NonLocalPointerDeps[CacheKey]; + Cache = &CacheInfo->NonLocalDeps; + NumSortedEntries = Cache->size(); + } + + // Since we failed phi translation, the "Cache" set won't contain all of the + // results for the query. This is ok (we can still use it to accelerate + // specific block queries) but we can't do the fastpath "return all + // results from the set". Clear out the indicator for this. + CacheInfo->Pair = BBSkipFirstBlockPair(); + + // If *nothing* works, mark the pointer as unknown. + // + // If this is the magic first block, return this as a clobber of the whole + // incoming value. Since we can't phi translate to one of the predecessors, + // we have to bail out. + if (SkipFirstBlock) + return true; + + for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) { + assert(I != Cache->rend() && "Didn't find current block??"); + if (I->getBB() != BB) + continue; + + assert(I->getResult().isNonLocal() && + "Should only be here with transparent block"); + I->setResult(MemDepResult::getUnknown()); + Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), + Pointer.getAddr())); + break; + } + } + + // Okay, we're done now. If we added new values to the cache, re-sort it. + SortNonLocalDepInfoCache(*Cache, NumSortedEntries); + DEBUG(AssertSorted(*Cache)); + return false; +} + +/// RemoveCachedNonLocalPointerDependencies - If P exists in +/// CachedNonLocalPointerInfo, remove it. +void MemoryDependenceAnalysis:: +RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) { + CachedNonLocalPointerInfo::iterator It = + NonLocalPointerDeps.find(P); + if (It == NonLocalPointerDeps.end()) return; + + // Remove all of the entries in the BB->val map. This involves removing + // instructions from the reverse map. + NonLocalDepInfo &PInfo = It->second.NonLocalDeps; + + for (unsigned i = 0, e = PInfo.size(); i != e; ++i) { + Instruction *Target = PInfo[i].getResult().getInst(); + if (Target == 0) continue; // Ignore non-local dep results. + assert(Target->getParent() == PInfo[i].getBB()); + + // Eliminating the dirty entry from 'Cache', so update the reverse info. + RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P); + } + + // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo). + NonLocalPointerDeps.erase(It); +} + + +/// invalidateCachedPointerInfo - This method is used to invalidate cached +/// information about the specified pointer, because it may be too +/// conservative in memdep. This is an optional call that can be used when +/// the client detects an equivalence between the pointer and some other +/// value and replaces the other value with ptr. This can make Ptr available +/// in more places that cached info does not necessarily keep. +void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) { + // If Ptr isn't really a pointer, just ignore it. + if (!Ptr->getType()->isPointerTy()) return; + // Flush store info for the pointer. + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false)); + // Flush load info for the pointer. + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true)); +} + +/// invalidateCachedPredecessors - Clear the PredIteratorCache info. +/// This needs to be done when the CFG changes, e.g., due to splitting +/// critical edges. +void MemoryDependenceAnalysis::invalidateCachedPredecessors() { + PredCache->clear(); +} + +/// removeInstruction - Remove an instruction from the dependence analysis, +/// updating the dependence of instructions that previously depended on it. +/// This method attempts to keep the cache coherent using the reverse map. +void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) { + // Walk through the Non-local dependencies, removing this one as the value + // for any cached queries. + NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst); + if (NLDI != NonLocalDeps.end()) { + NonLocalDepInfo &BlockMap = NLDI->second.first; + for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end(); + DI != DE; ++DI) + if (Instruction *Inst = DI->getResult().getInst()) + RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst); + NonLocalDeps.erase(NLDI); + } + + // If we have a cached local dependence query for this instruction, remove it. + // + LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst); + if (LocalDepEntry != LocalDeps.end()) { + // Remove us from DepInst's reverse set now that the local dep info is gone. + if (Instruction *Inst = LocalDepEntry->second.getInst()) + RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst); + + // Remove this local dependency info. + LocalDeps.erase(LocalDepEntry); + } + + // If we have any cached pointer dependencies on this instruction, remove + // them. If the instruction has non-pointer type, then it can't be a pointer + // base. + + // Remove it from both the load info and the store info. The instruction + // can't be in either of these maps if it is non-pointer. + if (RemInst->getType()->isPointerTy()) { + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false)); + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true)); + } + + // Loop over all of the things that depend on the instruction we're removing. + // + SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd; + + // If we find RemInst as a clobber or Def in any of the maps for other values, + // we need to replace its entry with a dirty version of the instruction after + // it. If RemInst is a terminator, we use a null dirty value. + // + // Using a dirty version of the instruction after RemInst saves having to scan + // the entire block to get to this point. + MemDepResult NewDirtyVal; + if (!RemInst->isTerminator()) + NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst)); + + ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst); + if (ReverseDepIt != ReverseLocalDeps.end()) { + SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second; + // RemInst can't be the terminator if it has local stuff depending on it. + assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) && + "Nothing can locally depend on a terminator"); + + for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(), + E = ReverseDeps.end(); I != E; ++I) { + Instruction *InstDependingOnRemInst = *I; + assert(InstDependingOnRemInst != RemInst && + "Already removed our local dep info"); + + LocalDeps[InstDependingOnRemInst] = NewDirtyVal; + + // Make sure to remember that new things depend on NewDepInst. + assert(NewDirtyVal.getInst() && "There is no way something else can have " + "a local dep on this if it is a terminator!"); + ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(), + InstDependingOnRemInst)); + } + + ReverseLocalDeps.erase(ReverseDepIt); + + // Add new reverse deps after scanning the set, to avoid invalidating the + // 'ReverseDeps' reference. + while (!ReverseDepsToAdd.empty()) { + ReverseLocalDeps[ReverseDepsToAdd.back().first] + .insert(ReverseDepsToAdd.back().second); + ReverseDepsToAdd.pop_back(); + } + } + + ReverseDepIt = ReverseNonLocalDeps.find(RemInst); + if (ReverseDepIt != ReverseNonLocalDeps.end()) { + SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second; + for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end(); + I != E; ++I) { + assert(*I != RemInst && "Already removed NonLocalDep info for RemInst"); + + PerInstNLInfo &INLD = NonLocalDeps[*I]; + // The information is now dirty! + INLD.second = true; + + for (NonLocalDepInfo::iterator DI = INLD.first.begin(), + DE = INLD.first.end(); DI != DE; ++DI) { + if (DI->getResult().getInst() != RemInst) continue; + + // Convert to a dirty entry for the subsequent instruction. + DI->setResult(NewDirtyVal); + + if (Instruction *NextI = NewDirtyVal.getInst()) + ReverseDepsToAdd.push_back(std::make_pair(NextI, *I)); + } + } + + ReverseNonLocalDeps.erase(ReverseDepIt); + + // Add new reverse deps after scanning the set, to avoid invalidating 'Set' + while (!ReverseDepsToAdd.empty()) { + ReverseNonLocalDeps[ReverseDepsToAdd.back().first] + .insert(ReverseDepsToAdd.back().second); + ReverseDepsToAdd.pop_back(); + } + } + + // If the instruction is in ReverseNonLocalPtrDeps then it appears as a + // value in the NonLocalPointerDeps info. + ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt = + ReverseNonLocalPtrDeps.find(RemInst); + if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) { + SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second; + SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd; + + for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(), + E = Set.end(); I != E; ++I) { + ValueIsLoadPair P = *I; + assert(P.getPointer() != RemInst && + "Already removed NonLocalPointerDeps info for RemInst"); + + NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].NonLocalDeps; + + // The cache is not valid for any specific block anymore. + NonLocalPointerDeps[P].Pair = BBSkipFirstBlockPair(); + + // Update any entries for RemInst to use the instruction after it. + for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end(); + DI != DE; ++DI) { + if (DI->getResult().getInst() != RemInst) continue; + + // Convert to a dirty entry for the subsequent instruction. + DI->setResult(NewDirtyVal); + + if (Instruction *NewDirtyInst = NewDirtyVal.getInst()) + ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P)); + } + + // Re-sort the NonLocalDepInfo. Changing the dirty entry to its + // subsequent value may invalidate the sortedness. + std::sort(NLPDI.begin(), NLPDI.end()); + } + + ReverseNonLocalPtrDeps.erase(ReversePtrDepIt); + + while (!ReversePtrDepsToAdd.empty()) { + ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first] + .insert(ReversePtrDepsToAdd.back().second); + ReversePtrDepsToAdd.pop_back(); + } + } + + + assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?"); + AA->deleteValue(RemInst); + DEBUG(verifyRemoved(RemInst)); +} +/// verifyRemoved - Verify that the specified instruction does not occur +/// in our internal data structures. +void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const { + for (LocalDepMapType::const_iterator I = LocalDeps.begin(), + E = LocalDeps.end(); I != E; ++I) { + assert(I->first != D && "Inst occurs in data structures"); + assert(I->second.getInst() != D && + "Inst occurs in data structures"); + } + + for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(), + E = NonLocalPointerDeps.end(); I != E; ++I) { + assert(I->first.getPointer() != D && "Inst occurs in NLPD map key"); + const NonLocalDepInfo &Val = I->second.NonLocalDeps; + for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end(); + II != E; ++II) + assert(II->getResult().getInst() != D && "Inst occurs as NLPD value"); + } + + for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(), + E = NonLocalDeps.end(); I != E; ++I) { + assert(I->first != D && "Inst occurs in data structures"); + const PerInstNLInfo &INLD = I->second; + for (NonLocalDepInfo::const_iterator II = INLD.first.begin(), + EE = INLD.first.end(); II != EE; ++II) + assert(II->getResult().getInst() != D && "Inst occurs in data structures"); + } + + for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(), + E = ReverseLocalDeps.end(); I != E; ++I) { + assert(I->first != D && "Inst occurs in data structures"); + for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(), + EE = I->second.end(); II != EE; ++II) + assert(*II != D && "Inst occurs in data structures"); + } + + for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(), + E = ReverseNonLocalDeps.end(); + I != E; ++I) { + assert(I->first != D && "Inst occurs in data structures"); + for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(), + EE = I->second.end(); II != EE; ++II) + assert(*II != D && "Inst occurs in data structures"); + } + + for (ReverseNonLocalPtrDepTy::const_iterator + I = ReverseNonLocalPtrDeps.begin(), + E = ReverseNonLocalPtrDeps.end(); I != E; ++I) { + assert(I->first != D && "Inst occurs in rev NLPD map"); + + for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(), + E = I->second.end(); II != E; ++II) + assert(*II != ValueIsLoadPair(D, false) && + *II != ValueIsLoadPair(D, true) && + "Inst occurs in ReverseNonLocalPtrDeps map"); + } + +} |