X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FMemoryDependenceAnalysis.cpp;h=6af365b76a902e4e1ab61626c7abf323b97b34bf;hb=ef4cfc749a61d0d0252196c957697436ba7ec068;hp=7c00a6c2f69561f2eb0899e2241812b8f04ab3b8;hpb=8ef57c5faf77890828ac439482420646b2a0beb8;p=oota-llvm.git diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index 7c00a6c2f69..6af365b76a9 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -22,8 +22,7 @@ #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/ADT/Statistic.h" #include "llvm/ADT/STLExtras.h" -#include "llvm/Support/CFG.h" -#include "llvm/Support/CommandLine.h" +#include "llvm/Support/PredIteratorCache.h" #include "llvm/Support/Debug.h" #include "llvm/Target/TargetData.h" using namespace llvm; @@ -31,12 +30,41 @@ 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"); + char MemoryDependenceAnalysis::ID = 0; // Register this pass... static RegisterPass X("memdep", "Memory Dependence Analysis", false, true); +MemoryDependenceAnalysis::MemoryDependenceAnalysis() +: FunctionPass(&ID), PredCache(0) { +} +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 { @@ -48,15 +76,32 @@ void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const { bool MemoryDependenceAnalysis::runOnFunction(Function &) { AA = &getAnalysis(); TD = &getAnalysis(); + 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 +static void RemoveFromReverseMap(DenseMap > &ReverseMap, + Instruction *Inst, KeyTy *Val) { + typename DenseMap >::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!"); Found=Found; + if (InstIt->second.empty()) + ReverseMap.erase(InstIt); +} + /// getCallSiteDependencyFrom - Private helper for finding the local /// dependencies of a call site. MemDepResult MemoryDependenceAnalysis:: -getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt, - BasicBlock *BB) { +getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall, + BasicBlock::iterator ScanIt, BasicBlock *BB) { // Walk backwards through the block, looking for dependencies while (ScanIt != BB->begin()) { Instruction *Inst = --ScanIt; @@ -74,24 +119,35 @@ getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt, Pointer = F->getPointerOperand(); // FreeInsts erase the entire structure - PointerSize = ~0UL; + PointerSize = ~0ULL; } else if (isa(Inst) || isa(Inst)) { CallSite InstCS = CallSite::get(Inst); // If these two calls do not interfere, look past it. - if (AA->getModRefInfo(CS, InstCS) == AliasAnalysis::NoModRef) + switch (AA->getModRefInfo(CS, InstCS)) { + case AliasAnalysis::NoModRef: + // If the two calls don't interact (e.g. InstCS is readnone) keep + // scanning. continue; - - // FIXME: If this is a ref/ref result, we should ignore it! - // X = strlen(P); - // Y = strlen(Q); - // Z = strlen(P); // Z = X - - // If they interfere, we generally return clobber. However, if they are - // calls to the same read-only functions we return Def. - if (!AA->onlyReadsMemory(CS) || CS.getCalledFunction() == 0 || - CS.getCalledFunction() != InstCS.getCalledFunction()) + case AliasAnalysis::Ref: + // If the two calls read the same memory locations and CS is a readonly + // function, then we have two cases: 1) the calls may not interfere with + // each other at all. 2) the calls may produce the same value. In case + // #1 we want to ignore the values, in case #2, we want to return Inst + // as a Def dependence. This allows us to CSE in cases like: + // X = strlen(P); + // memchr(...); + // Y = strlen(P); // Y = X + if (isReadOnlyCall) { + if (CS.getCalledFunction() != 0 && + CS.getCalledFunction() == InstCS.getCalledFunction()) + return MemDepResult::getDef(Inst); + // Ignore unrelated read/read call dependences. + continue; + } + // FALL THROUGH + default: return MemDepResult::getClobber(Inst); - return MemDepResult::getDef(Inst); + } } else { // Non-memory instruction. continue; @@ -101,52 +157,21 @@ getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt, return MemDepResult::getClobber(Inst); } - // No dependence found. - return MemDepResult::getNonLocal(); + // No dependence found. If this is the entry block of the function, it is a + // clobber, otherwise it is non-local. + if (BB != &BB->getParent()->getEntryBlock()) + return MemDepResult::getNonLocal(); + return MemDepResult::getClobber(ScanIt); } -/// getDependencyFrom - Return the instruction on which a memory operation -/// depends. +/// getPointerDependencyFrom - Return the instruction on which a memory +/// location depends. If isLoad is true, this routine ignore may-aliases with +/// read-only operations. MemDepResult MemoryDependenceAnalysis:: -getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt, - BasicBlock *BB) { - // The first instruction in a block is always non-local. - if (ScanIt == BB->begin()) - return MemDepResult::getNonLocal(); - - // Get the pointer value for which dependence will be determined - Value *MemPtr = 0; - uint64_t MemSize = 0; - - if (StoreInst* S = dyn_cast(QueryInst)) { - // If this is a volatile store, don't mess around with it. Just return the - // previous instruction as a clobber. - if (S->isVolatile()) - return MemDepResult::getClobber(--ScanIt); +getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad, + BasicBlock::iterator ScanIt, BasicBlock *BB) { - MemPtr = S->getPointerOperand(); - MemSize = TD->getTypeStoreSize(S->getOperand(0)->getType()); - } else if (LoadInst* LI = dyn_cast(QueryInst)) { - // If this is a volatile load, don't mess around with it. Just return the - // previous instruction as a clobber. - if (S->isVolatile()) - return MemDepResult::getClobber(--ScanIt); - - MemPtr = LI->getPointerOperand(); - MemSize = TD->getTypeStoreSize(LI->getType()); - } else if (FreeInst* F = dyn_cast(QueryInst)) { - MemPtr = F->getPointerOperand(); - // FreeInsts erase the entire structure, not just a field. - MemSize = ~0UL; - } else if (isa(QueryInst) || isa(QueryInst)) { - return getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanIt, BB); - } else { - // Otherwise, this is a vaarg or non-memory instruction, just return a - // clobber dependency on the previous inst. - return MemDepResult::getClobber(--ScanIt); - } - - // Walk backwards through the basic block, looking for dependencies + // Walk backwards through the basic block, looking for dependencies. while (ScanIt != BB->begin()) { Instruction *Inst = --ScanIt; @@ -163,8 +188,10 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt, continue; // May-alias loads don't depend on each other without a dependence. - if (isa(QueryInst) && R == AliasAnalysis::MayAlias) + if (isLoad && R == AliasAnalysis::MayAlias) continue; + // Stores depend on may and must aliased loads, loads depend on must-alias + // loads. return MemDepResult::getDef(Inst); } @@ -197,15 +224,27 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt, } // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer. - if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef) + switch (AA->getModRefInfo(Inst, MemPtr, MemSize)) { + case AliasAnalysis::NoModRef: + // If the call has no effect on the queried pointer, just ignore it. continue; - - // Otherwise, there is a dependence. - 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; + // FALL THROUGH. + default: + // Otherwise, there is a potential dependence. Return a clobber. + return MemDepResult::getClobber(Inst); + } } - // If we found nothing, return the non-local flag. - return MemDepResult::getNonLocal(); + // No dependence found. If this is the entry block of the function, it is a + // clobber, otherwise it is non-local. + if (BB != &BB->getParent()->getEntryBlock()) + return MemDepResult::getNonLocal(); + return MemDepResult::getClobber(ScanIt); } /// getDependency - Return the instruction on which a memory operation @@ -226,14 +265,59 @@ MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) { if (Instruction *Inst = LocalCache.getInst()) { ScanPos = Inst; - SmallPtrSet &InstMap = ReverseLocalDeps[Inst]; - InstMap.erase(QueryInst); - if (InstMap.empty()) - ReverseLocalDeps.erase(Inst); + RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst); } + BasicBlock *QueryParent = QueryInst->getParent(); + + Value *MemPtr = 0; + uint64_t MemSize = 0; + // Do the scan. - LocalCache = getDependencyFrom(QueryInst, ScanPos, QueryInst->getParent()); + if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) { + // No dependence found. If this is the entry block of the function, it is a + // clobber, otherwise it is non-local. + if (QueryParent != &QueryParent->getParent()->getEntryBlock()) + LocalCache = MemDepResult::getNonLocal(); + else + LocalCache = MemDepResult::getClobber(QueryInst); + } else if (StoreInst *SI = dyn_cast(QueryInst)) { + // If this is a volatile store, don't mess around with it. Just return the + // previous instruction as a clobber. + if (SI->isVolatile()) + LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos)); + else { + MemPtr = SI->getPointerOperand(); + MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType()); + } + } else if (LoadInst *LI = dyn_cast(QueryInst)) { + // If this is a volatile load, don't mess around with it. Just return the + // previous instruction as a clobber. + if (LI->isVolatile()) + LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos)); + else { + MemPtr = LI->getPointerOperand(); + MemSize = TD->getTypeStoreSize(LI->getType()); + } + } else if (isa(QueryInst) || isa(QueryInst)) { + CallSite QueryCS = CallSite::get(QueryInst); + bool isReadOnly = AA->onlyReadsMemory(QueryCS); + LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos, + QueryParent); + } else if (FreeInst *FI = dyn_cast(QueryInst)) { + MemPtr = FI->getPointerOperand(); + // FreeInsts erase the entire structure, not just a field. + MemSize = ~0UL; + } else { + // Non-memory instruction. + LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos)); + } + + // If we need to do a pointer scan, make it happen. + if (MemPtr) + LocalCache = getPointerDependencyFrom(MemPtr, MemSize, + isa(QueryInst), + ScanPos, QueryParent); // Remember the result! if (Instruction *I = LocalCache.getInst()) @@ -242,20 +326,36 @@ MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) { return LocalCache; } -/// getNonLocalDependency - Perform a full dependency query for the -/// specified instruction, returning the set of blocks that the value is +#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-1] <= Cache[i] && "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 +/// 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::getNonLocalDependency(Instruction *QueryInst) { - assert(getDependency(QueryInst).isNonLocal() && - "getNonLocalDependency should only be used on insts with non-local deps!"); - PerInstNLInfo &CacheP = NonLocalDeps[QueryInst]; - +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 @@ -287,15 +387,19 @@ MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) { // << Cache.size() << " cached: " << *QueryInst; } else { // Seed DirtyBlocks with each of the preds of QueryInst's block. - BasicBlock *QueryBB = QueryInst->getParent(); - DirtyBlocks.append(pred_begin(QueryBB), pred_end(QueryBB)); + BasicBlock *QueryBB = QueryCS.getInstruction()->getParent(); + for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI) + DirtyBlocks.push_back(*PI); NumUncacheNonLocal++; } - // Visited checked first, vector in sorted order. + // isReadonlyCall - If this is a read-only call, we can be more aggressive. + bool isReadonlyCall = AA->onlyReadsMemory(QueryCS); + SmallPtrSet Visited; unsigned NumSortedEntries = Cache.size(); + DEBUG(AssertSorted(Cache)); // Iterate while we still have blocks to update. while (!DirtyBlocks.empty()) { @@ -308,10 +412,11 @@ MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) { // 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, std::make_pair(DirtyBB, MemDepResult())); - if (Entry != Cache.begin() && (&*Entry)[-1].first == DirtyBB) + if (Entry != Cache.begin() && prior(Entry)->first == DirtyBB) --Entry; MemDepResult *ExistingResult = 0; @@ -332,16 +437,24 @@ MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) { if (ExistingResult) { if (Instruction *Inst = ExistingResult->getInst()) { ScanPos = Inst; - // We're removing QueryInst's use of Inst. - SmallPtrSet &InstMap = ReverseNonLocalDeps[Inst]; - InstMap.erase(QueryInst); - if (InstMap.empty()) ReverseNonLocalDeps.erase(Inst); + RemoveFromReverseMap(ReverseNonLocalDeps, Inst, + QueryCS.getInstruction()); } } // Find out if this block has a local dependency for QueryInst. - MemDepResult Dep = getDependencyFrom(QueryInst, ScanPos, DirtyBB); + 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 non-local. + Dep = MemDepResult::getNonLocal(); + } else { + Dep = MemDepResult::getClobber(ScanPos); + } // If we had a dirty entry for the block, update it. Otherwise, just add // a new entry. @@ -356,18 +469,437 @@ MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) { // 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(QueryInst); + 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. - DirtyBlocks.append(pred_begin(DirtyBB), pred_end(DirtyBB)); + 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(Value *Pointer, bool isLoad, BasicBlock *FromBB, + SmallVectorImpl &Result) { + assert(isa(Pointer->getType()) && + "Can't get pointer deps of a non-pointer!"); + Result.clear(); + + // We know that the pointer value is live into FromBB find the def/clobbers + // from presecessors. + const Type *EltTy = cast(Pointer->getType())->getElementType(); + uint64_t PointeeSize = TD->getTypeStoreSize(EltTy); + + // 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 Visited; + if (!getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB, + Result, Visited, true)) + return; + Result.clear(); + Result.push_back(std::make_pair(FromBB, + MemDepResult::getClobber(FromBB->begin()))); +} + +/// 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(Value *Pointer, uint64_t PointeeSize, + 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, + std::make_pair(BB, MemDepResult())); + if (Entry != Cache->begin() && prior(Entry)->first == BB) + --Entry; + + MemDepResult *ExistingResult = 0; + if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB) + ExistingResult = &Entry->second; + + // If we have a cached entry, and it is non-dirty, use it as the value for + // this dependency. + if (ExistingResult && !ExistingResult->isDirty()) { + ++NumCacheNonLocalPtr; + return *ExistingResult; + } + + // 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->getInst()) { + assert(ExistingResult->getInst()->getParent() == BB && + "Instruction invalidated?"); + ++NumCacheDirtyNonLocalPtr; + ScanPos = ExistingResult->getInst(); + + // Eliminating the dirty entry from 'Cache', so update the reverse info. + ValueIsLoadPair CacheKey(Pointer, isLoad); + RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, + CacheKey.getOpaqueValue()); + } else { + ++NumUncacheNonLocalPtr; + } + + // Scan the block for the dependency. + MemDepResult Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad, + ScanPos, BB); + + // If we had a dirty entry for the block, update it. Otherwise, just add + // a new entry. + if (ExistingResult) + *ExistingResult = Dep; + else + Cache->push_back(std::make_pair(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.isNonLocal()) + 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(Pointer, isLoad); + ReverseNonLocalPtrDeps[Inst].insert(CacheKey.getOpaqueValue()); + return Dep; +} + + +/// 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(Value *Pointer, uint64_t PointeeSize, + bool isLoad, BasicBlock *StartBB, + SmallVectorImpl &Result, + DenseMap &Visited, + bool SkipFirstBlock) { + + // Look up the cached info for Pointer. + ValueIsLoadPair CacheKey(Pointer, isLoad); + + std::pair *CacheInfo = + &NonLocalPointerDeps[CacheKey]; + NonLocalDepInfo *Cache = &CacheInfo->second; + + // If we have valid cached information for exactly the block we are + // investigating, just return it with no recomputation. + if (CacheInfo->first == 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::iterator VI = Visited.find(I->first); + if (VI == Visited.end() || VI->second == Pointer) 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; + } + } + + for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end(); + I != E; ++I) { + Visited.insert(std::make_pair(I->first, Pointer)); + if (!I->second.isNonLocal()) + Result.push_back(*I); + } + ++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->first = BBSkipFirstBlockPair(StartBB, SkipFirstBlock); + else + CacheInfo->first = BBSkipFirstBlockPair(); + + SmallVector Worklist; + Worklist.push_back(StartBB); + + // 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(Pointer, PointeeSize, isLoad, + BB, Cache, NumSortedEntries); + + // If we got a Def or Clobber, add this to the list of results. + if (!Dep.isNonLocal()) { + Result.push_back(NonLocalDepEntry(BB, Dep)); + 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 phi translation fails, then we can't continue dependence analysis. + Instruction *PtrInst = dyn_cast(Pointer); + bool NeedsPHITranslation = PtrInst && PtrInst->getParent() == BB; + + // If no PHI translation is needed, just add all the predecessors of this + // block to scan them as well. + if (!NeedsPHITranslation) { + SkipFirstBlock = false; + for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { + // Verify that we haven't looked at this block yet. + std::pair::iterator, bool> + InsertRes = Visited.insert(std::make_pair(*PI, Pointer)); + if (InsertRes.second) { + // First time we've looked at *PI. + Worklist.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) + goto PredTranslationFailure; + } + continue; + } + + // If we do need to do phi translation, then there are a bunch of different + // cases, because we have to find a Value* live in the predecessor block. We + // know that PtrInst is defined in this block at least. + + // If this is directly a PHI node, just use the incoming values for each + // pred as the phi translated version. + if (PHINode *PtrPHI = dyn_cast(PtrInst)) { + for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { + BasicBlock *Pred = *PI; + Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred); + + // 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::iterator, bool> + InsertRes = Visited.insert(std::make_pair(Pred, PredPtr)); + + if (!InsertRes.second) { + // If the predecessor was visited with PredPtr, then we already did + // the analysis and can ignore it. + if (InsertRes.first->second == PredPtr) + 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. + 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 that could reuse the cache + // value will only see properly sorted cache arrays. + if (Cache && NumSortedEntries != Cache->size()) + std::sort(Cache->begin(), Cache->end()); + Cache = 0; + + // 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 we have a problem phi translating, fall through to the code below + // to handle the failure condition. + if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred, + Result, Visited)) + goto PredTranslationFailure; + } + + // Refresh the CacheInfo/Cache pointer so that it isn't invalidated. + CacheInfo = &NonLocalPointerDeps[CacheKey]; + Cache = &CacheInfo->second; + 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->first = BBSkipFirstBlockPair(); + SkipFirstBlock = false; + continue; + } + + // TODO: BITCAST, GEP. + + // cerr << "MEMDEP: Could not PHI translate: " << *Pointer; + // if (isa(PtrInst) || isa(PtrInst)) + // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0); + PredTranslationFailure: + + if (Cache == 0) { + // Refresh the CacheInfo/Cache pointer if it got invalidated. + CacheInfo = &NonLocalPointerDeps[CacheKey]; + Cache = &CacheInfo->second; + NumSortedEntries = Cache->size(); + } else if (NumSortedEntries != Cache->size()) { + std::sort(Cache->begin(), Cache->end()); + 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->first = BBSkipFirstBlockPair(); + + // If *nothing* works, mark the pointer as being clobbered by the first + // instruction in this block. + // + // 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->first != BB) + continue; + + assert(I->second.isNonLocal() && + "Should only be here with transparent block"); + I->second = MemDepResult::getClobber(BB->begin()); + ReverseNonLocalPtrDeps[BB->begin()].insert(CacheKey.getOpaqueValue()); + Result.push_back(*I); + break; + } + } + + // Okay, we're done now. If we added new values to the cache, re-sort it. + 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(); + 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(); + 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()); + } + 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.second; + + for (unsigned i = 0, e = PInfo.size(); i != e; ++i) { + Instruction *Target = PInfo[i].second.getInst(); + if (Target == 0) continue; // Ignore non-local dep results. + assert(Target->getParent() == PInfo[i].first); + + // Eliminating the dirty entry from 'Cache', so update the reverse info. + RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P.getOpaqueValue()); + } + + // 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 (!isa(Ptr->getType())) return; + // Flush store info for the pointer. + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false)); + // Flush load info for the pointer. + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true)); +} + /// 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. @@ -380,7 +912,7 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) { for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end(); DI != DE; ++DI) if (Instruction *Inst = DI->second.getInst()) - ReverseNonLocalDeps[Inst].erase(RemInst); + RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst); NonLocalDeps.erase(NLDI); } @@ -389,44 +921,57 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) { 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()) { - SmallPtrSet &RLD = ReverseLocalDeps[Inst]; - RLD.erase(RemInst); - if (RLD.empty()) - ReverseLocalDeps.erase(Inst); - } + 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 (isa(RemInst->getType())) { + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false)); + RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true)); + } // Loop over all of the things that depend on the instruction we're removing. // SmallVector, 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 &ReverseDeps = ReverseDepIt->second; - // RemInst can't be the terminator if it has stuff depending on it. + // RemInst can't be the terminator if it has local stuff depending on it. assert(!ReverseDeps.empty() && !isa(RemInst) && "Nothing can locally depend on a terminator"); - // Anything that was locally dependent on RemInst is now going to be - // dependent on the instruction after RemInst. It will have the dirty flag - // set so it will rescan. This saves having to scan the entire block to get - // to this point. - Instruction *NewDepInst = next(BasicBlock::iterator(RemInst)); - for (SmallPtrSet::iterator I = ReverseDeps.begin(), E = ReverseDeps.end(); I != E; ++I) { Instruction *InstDependingOnRemInst = *I; assert(InstDependingOnRemInst != RemInst && "Already removed our local dep info"); - LocalDeps[InstDependingOnRemInst] = MemDepResult::getDirty(NewDepInst); + LocalDeps[InstDependingOnRemInst] = NewDirtyVal; // Make sure to remember that new things depend on NewDepInst. - ReverseDepsToAdd.push_back(std::make_pair(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)); } @@ -443,8 +988,8 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) { ReverseDepIt = ReverseNonLocalDeps.find(RemInst); if (ReverseDepIt != ReverseNonLocalDeps.end()) { - SmallPtrSet& set = ReverseDepIt->second; - for (SmallPtrSet::iterator I = set.begin(), E = set.end(); + SmallPtrSet &Set = ReverseDepIt->second; + for (SmallPtrSet::iterator I = Set.begin(), E = Set.end(); I != E; ++I) { assert(*I != RemInst && "Already removed NonLocalDep info for RemInst"); @@ -457,12 +1002,10 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) { if (DI->second.getInst() != RemInst) continue; // Convert to a dirty entry for the subsequent instruction. - Instruction *NextI = 0; - if (!RemInst->isTerminator()) { - NextI = next(BasicBlock::iterator(RemInst)); + DI->second = NewDirtyVal; + + if (Instruction *NextI = NewDirtyVal.getInst()) ReverseDepsToAdd.push_back(std::make_pair(NextI, *I)); - } - DI->second = MemDepResult::getDirty(NextI); } } @@ -476,11 +1019,57 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) { } } + // 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 &Set = ReversePtrDepIt->second; + SmallVector,8> ReversePtrDepsToAdd; + + for (SmallPtrSet::iterator I = Set.begin(), E = Set.end(); + I != E; ++I) { + ValueIsLoadPair P; + P.setFromOpaqueValue(*I); + assert(P.getPointer() != RemInst && + "Already removed NonLocalPointerDeps info for RemInst"); + + NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].second; + + // The cache is not valid for any specific block anymore. + NonLocalPointerDeps[P].first = 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->second.getInst() != RemInst) continue; + + // Convert to a dirty entry for the subsequent instruction. + DI->second = 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.getOpaqueValue()); + 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 { @@ -491,6 +1080,15 @@ void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const { "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.second; + for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end(); + II != E; ++II) + assert(II->second.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"); @@ -516,4 +1114,17 @@ void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const { 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::const_iterator II = I->second.begin(), + E = I->second.end(); II != E; ++II) + assert(*II != ValueIsLoadPair(D, false).getOpaqueValue() && + *II != ValueIsLoadPair(D, true).getOpaqueValue() && + "Inst occurs in ReverseNonLocalPtrDeps map"); + } + }