//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the Owen Anderson and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "memdep"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Function.h"
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Target/TargetData.h"
#include "llvm/ADT/Statistic.h"
-
-#define DEBUG_TYPE "memdep"
-
+#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 cached non-local responses");
-STATISTIC(NumUncacheNonlocal, "Number of uncached non-local responses");
+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;
-Instruction* const MemoryDependenceAnalysis::NonLocal = (Instruction*)-3;
-Instruction* const MemoryDependenceAnalysis::None = (Instruction*)-4;
-
// Register this pass...
static RegisterPass<MemoryDependenceAnalysis> X("memdep",
- "Memory Dependence Analysis");
+ "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.
///
AU.addRequiredTransitive<TargetData>();
}
-/// getCallSiteDependency - Private helper for finding the local dependencies
-/// of a call site.
-Instruction* MemoryDependenceAnalysis::getCallSiteDependency(CallSite C,
- Instruction* start,
- BasicBlock* block) {
-
- AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
- TargetData& TD = getAnalysis<TargetData>();
- BasicBlock::iterator blockBegin = C.getInstruction()->getParent()->begin();
- BasicBlock::iterator QI = C.getInstruction();
-
- // If the starting point was specifiy, use it
- if (start) {
- QI = start;
- blockBegin = start->getParent()->end();
- // If the starting point wasn't specified, but the block was, use it
- } else if (!start && block) {
- QI = block->end();
- blockBegin = block->end();
- }
-
+bool MemoryDependenceAnalysis::runOnFunction(Function &) {
+ AA = &getAnalysis<AliasAnalysis>();
+ TD = &getAnalysis<TargetData>();
+ 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!"); 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, bool isReadOnlyCall,
+ BasicBlock::iterator ScanIt, BasicBlock *BB) {
// Walk backwards through the block, looking for dependencies
- while (QI != blockBegin) {
- --QI;
+ while (ScanIt != BB->begin()) {
+ Instruction *Inst = --ScanIt;
// If this inst is a memory op, get the pointer it accessed
- Value* pointer = 0;
- uint64_t pointerSize = 0;
- if (StoreInst* S = dyn_cast<StoreInst>(QI)) {
- pointer = S->getPointerOperand();
- pointerSize = TD.getTypeSize(S->getOperand(0)->getType());
- } else if (LoadInst* L = dyn_cast<LoadInst>(QI)) {
- pointer = L->getPointerOperand();
- pointerSize = TD.getTypeSize(L->getType());
- } else if (AllocationInst* AI = dyn_cast<AllocationInst>(QI)) {
- pointer = AI;
- if (ConstantInt* C = dyn_cast<ConstantInt>(AI->getArraySize()))
- pointerSize = C->getZExtValue() * \
- TD.getTypeSize(AI->getAllocatedType());
- else
- pointerSize = ~0UL;
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(QI)) {
- pointer = V->getOperand(0);
- pointerSize = TD.getTypeSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(QI)) {
- pointer = F->getPointerOperand();
+ Value *Pointer = 0;
+ uint64_t PointerSize = 0;
+ if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
+ Pointer = S->getPointerOperand();
+ PointerSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
+ } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
+ Pointer = V->getOperand(0);
+ PointerSize = TD->getTypeStoreSize(V->getType());
+ } else if (FreeInst *F = dyn_cast<FreeInst>(Inst)) {
+ Pointer = F->getPointerOperand();
// FreeInsts erase the entire structure
- pointerSize = ~0UL;
- } else if (CallSite::get(QI).getInstruction() != 0) {
- if (AA.getModRefInfo(C, CallSite::get(QI)) != AliasAnalysis::NoModRef) {
- if (!start && !block) {
- depGraphLocal.insert(std::make_pair(C.getInstruction(),
- std::make_pair(QI, true)));
- reverseDep[QI].insert(C.getInstruction());
- }
- return QI;
- } else {
+ PointerSize = ~0ULL;
+ } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
+ CallSite InstCS = CallSite::get(Inst);
+ // If these two calls do not interfere, look past it.
+ switch (AA->getModRefInfo(CS, InstCS)) {
+ case AliasAnalysis::NoModRef:
+ // If the two calls don't interact (e.g. InstCS is readnone) keep
+ // scanning.
continue;
+ 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);
}
- } else
+ } else {
+ // Non-memory instruction.
continue;
-
- if (AA.getModRefInfo(C, pointer, pointerSize) != AliasAnalysis::NoModRef) {
- if (!start && !block) {
- depGraphLocal.insert(std::make_pair(C.getInstruction(),
- std::make_pair(QI, true)));
- reverseDep[QI].insert(C.getInstruction());
- }
- return QI;
}
+
+ if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
+ return MemDepResult::getClobber(Inst);
}
- // No dependence found
- depGraphLocal.insert(std::make_pair(C.getInstruction(),
- std::make_pair(NonLocal, true)));
- reverseDep[NonLocal].insert(C.getInstruction());
- return NonLocal;
+ // 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);
}
-/// nonLocalHelper - Private helper used to calculate non-local dependencies
-/// by doing DFS on the predecessors of a block to find its dependencies
-void MemoryDependenceAnalysis::nonLocalHelper(Instruction* query,
- BasicBlock* block,
- DenseMap<BasicBlock*, Value*>& resp) {
- // Set of blocks that we've already visited in our DFS
- SmallPtrSet<BasicBlock*, 4> visited;
- // Current stack of the DFS
- SmallVector<BasicBlock*, 4> stack;
- stack.push_back(block);
-
- // Do a basic DFS
- while (!stack.empty()) {
- BasicBlock* BB = stack.back();
-
- // If we've already visited this block, no need to revist
- if (visited.count(BB)) {
- stack.pop_back();
- continue;
- }
-
- // If we find a new block with a local dependency for query,
- // then we insert the new dependency and backtrack.
- if (BB != block) {
- visited.insert(BB);
+/// 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::
+getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
+ BasicBlock::iterator ScanIt, BasicBlock *BB) {
+
+ // Walk backwards through the basic block, looking for dependencies.
+ while (ScanIt != BB->begin()) {
+ Instruction *Inst = --ScanIt;
+
+ // 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)) {
+ Value *Pointer = LI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
- Instruction* localDep = getDependency(query, 0, BB);
- if (localDep != NonLocal) {
- resp.insert(std::make_pair(BB, localDep));
- stack.pop_back();
-
+ // If we found a pointer, check if it could be the same as our pointer.
+ AliasAnalysis::AliasResult R =
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
+ if (R == AliasAnalysis::NoAlias)
continue;
- }
- // If we re-encounter the starting block, we still need to search it
- // because there might be a dependency in the starting block AFTER
- // the position of the query. This is necessary to get loops right.
- } else if (BB == block && stack.size() > 1) {
- visited.insert(BB);
- Instruction* localDep = getDependency(query, 0, BB);
- if (localDep != query)
- resp.insert(std::make_pair(BB, localDep));
+ // May-alias loads don't depend on each other without a dependence.
+ if (isLoad && R == AliasAnalysis::MayAlias)
+ continue;
+ // Stores depend on may and must aliased loads, loads depend on must-alias
+ // loads.
+ return MemDepResult::getDef(Inst);
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ Value *Pointer = SI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
+
+ // If we found a pointer, check if it could be the same as our pointer.
+ AliasAnalysis::AliasResult R =
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
- stack.pop_back();
+ if (R == AliasAnalysis::NoAlias)
+ continue;
+ if (R == AliasAnalysis::MayAlias)
+ return MemDepResult::getClobber(Inst);
+ return MemDepResult::getDef(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.
+ if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
+ Value *AccessPtr = MemPtr->getUnderlyingObject();
+ if (AccessPtr == AI ||
+ AA->alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
+ return MemDepResult::getDef(AI);
continue;
}
- // If we didn't find anything, recurse on the precessors of this block
- bool predOnStack = false;
- bool inserted = false;
- for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
- PI != PE; ++PI)
- if (!visited.count(*PI)) {
- stack.push_back(*PI);
- inserted = true;
- } else
- predOnStack = true;
-
- // If we inserted a new predecessor, then we'll come back to this block
- if (inserted)
+ // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
+ switch (AA->getModRefInfo(Inst, MemPtr, MemSize)) {
+ case AliasAnalysis::NoModRef:
+ // If the call has no effect on the queried pointer, just ignore it.
continue;
- // If we didn't insert because we have no predecessors, then this
- // query has no dependency at all.
- else if (!inserted && !predOnStack) {
- resp.insert(std::make_pair(BB, None));
- // If we didn't insert because our predecessors are already on the stack,
- // then we might still have a dependency, but it will be discovered during
- // backtracking.
- } else if (!inserted && predOnStack){
- resp.insert(std::make_pair(BB, NonLocal));
+ 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);
}
+ }
+
+ // 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
+/// 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;
- stack.pop_back();
+ // 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();
+
+ Value *MemPtr = 0;
+ uint64_t MemSize = 0;
+
+ // Do the scan.
+ 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<StoreInst>(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<LoadInst>(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<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
+ CallSite QueryCS = CallSite::get(QueryInst);
+ bool isReadOnly = AA->onlyReadsMemory(QueryCS);
+ LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
+ QueryParent);
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(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<LoadInst>(QueryInst),
+ ScanPos, QueryParent);
+
+ // Remember the result!
+ if (Instruction *I = LocalCache.getInst())
+ ReverseLocalDeps[I].insert(QueryInst);
+
+ return LocalCache;
}
-/// getNonLocalDependency - Fills the passed-in map with the non-local
-/// dependencies of the queries. The map will contain NonLocal for
-/// blocks between the query and its dependencies.
-void MemoryDependenceAnalysis::getNonLocalDependency(Instruction* query,
- DenseMap<BasicBlock*, Value*>& resp) {
- if (depGraphNonLocal.count(query)) {
- resp = depGraphNonLocal[query];
- NumCacheNonlocal++;
- return;
- } else
- NumUncacheNonlocal++;
+#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
+/// 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 not, go ahead and search for non-local deps.
- nonLocalHelper(query, query->getParent(), resp);
+ 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->second.isDirty())
+ DirtyBlocks.push_back(I->first);
+
+ // 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++;
+ }
- // Update the non-local dependency cache
- for (DenseMap<BasicBlock*, Value*>::iterator I = resp.begin(), E = resp.end();
- I != E; ++I) {
- depGraphNonLocal[query].insert(*I);
- reverseDepNonLocal[I->second].insert(query);
+ // 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,
+ std::make_pair(DirtyBB, MemDepResult()));
+ if (Entry != Cache.begin() && prior(Entry)->first == DirtyBB)
+ --Entry;
+
+ MemDepResult *ExistingResult = 0;
+ if (Entry != Cache.begin()+NumSortedEntries &&
+ Entry->first == DirtyBB) {
+ // If we already have an entry, and if it isn't already dirty, the block
+ // is done.
+ if (!Entry->second.isDirty())
+ continue;
+
+ // Otherwise, remember this slot so we can update the value.
+ ExistingResult = &Entry->second;
+ }
+
+ // 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->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 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.
+ if (ExistingResult)
+ *ExistingResult = Dep;
+ else
+ Cache.push_back(std::make_pair(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;
}
-/// getDependency - Return the instruction on which a memory operation
-/// depends. The local paramter indicates if the query should only
-/// evaluate dependencies within the same basic block.
-Instruction* MemoryDependenceAnalysis::getDependency(Instruction* query,
- Instruction* start,
- BasicBlock* block) {
- // Start looking for dependencies with the queried inst
- BasicBlock::iterator QI = query;
+/// 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<NonLocalDepEntry> &Result) {
+ assert(isa<PointerType>(Pointer->getType()) &&
+ "Can't get pointer deps of a non-pointer!");
+ Result.clear();
- // Check for a cached result
- std::pair<Instruction*, bool> cachedResult = depGraphLocal[query];
- // If we have a _confirmed_ cached entry, return it
- if (cachedResult.second)
- return cachedResult.first;
- else if (cachedResult.first && cachedResult.first != NonLocal)
- // If we have an unconfirmed cached entry, we can start our search from there
- QI = cachedResult.first;
-
- if (start)
- QI = start;
- else if (!start && block)
- QI = block->end();
-
- AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
- TargetData& TD = getAnalysis<TargetData>();
-
- // Get the pointer value for which dependence will be determined
- Value* dependee = 0;
- uint64_t dependeeSize = 0;
- bool queryIsVolatile = false;
- if (StoreInst* S = dyn_cast<StoreInst>(query)) {
- dependee = S->getPointerOperand();
- dependeeSize = TD.getTypeSize(S->getOperand(0)->getType());
- queryIsVolatile = S->isVolatile();
- } else if (LoadInst* L = dyn_cast<LoadInst>(query)) {
- dependee = L->getPointerOperand();
- dependeeSize = TD.getTypeSize(L->getType());
- queryIsVolatile = L->isVolatile();
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(query)) {
- dependee = V->getOperand(0);
- dependeeSize = TD.getTypeSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(query)) {
- dependee = F->getPointerOperand();
-
- // FreeInsts erase the entire structure, not just a field
- dependeeSize = ~0UL;
- } else if (CallSite::get(query).getInstruction() != 0)
- return getCallSiteDependency(CallSite::get(query), start, block);
- else if (isa<AllocationInst>(query))
- return None;
- else
- return None;
+ // We know that the pointer value is live into FromBB find the def/clobbers
+ // from presecessors.
+ const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
+ uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
- BasicBlock::iterator blockBegin = block ? block->begin()
- : query->getParent()->begin();
+ // 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(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;
- // Walk backwards through the basic block, looking for dependencies
- while (QI != blockBegin) {
- --QI;
+ // 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();
- // If this inst is a memory op, get the pointer it accessed
- Value* pointer = 0;
- uint64_t pointerSize = 0;
- if (StoreInst* S = dyn_cast<StoreInst>(QI)) {
- // All volatile loads/stores depend on each other
- if (queryIsVolatile && S->isVolatile()) {
- if (!start && !block) {
- depGraphLocal.insert(std::make_pair(query, std::make_pair(S, true)));
- reverseDep[S].insert(query);
- }
+ // 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<NonLocalDepEntry> &Result,
+ DenseMap<BasicBlock*, Value*> &Visited,
+ bool SkipFirstBlock) {
+
+ // Look up the cached info for Pointer.
+ ValueIsLoadPair CacheKey(Pointer, isLoad);
+
+ std::pair<BBSkipFirstBlockPair, NonLocalDepInfo> *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<BasicBlock*, Value*>::iterator VI = Visited.find(I->first);
+ if (VI == Visited.end() || VI->second == Pointer) continue;
- return S;
+ // 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<BasicBlock*, 32> 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);
- pointer = S->getPointerOperand();
- pointerSize = TD.getTypeSize(S->getOperand(0)->getType());
- } else if (LoadInst* L = dyn_cast<LoadInst>(QI)) {
- // All volatile loads/stores depend on each other
- if (queryIsVolatile && L->isVolatile()) {
- if (!start && !block) {
- depGraphLocal.insert(std::make_pair(query, std::make_pair(L, true)));
- reverseDep[L].insert(query);
- }
-
- return L;
+ // If we got a Def or Clobber, add this to the list of results.
+ if (!Dep.isNonLocal()) {
+ Result.push_back(NonLocalDepEntry(BB, Dep));
+ continue;
}
-
- pointer = L->getPointerOperand();
- pointerSize = TD.getTypeSize(L->getType());
- } else if (AllocationInst* AI = dyn_cast<AllocationInst>(QI)) {
- pointer = AI;
- if (ConstantInt* C = dyn_cast<ConstantInt>(AI->getArraySize()))
- pointerSize = C->getZExtValue() * \
- TD.getTypeSize(AI->getAllocatedType());
- else
- pointerSize = ~0UL;
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(QI)) {
- pointer = V->getOperand(0);
- pointerSize = TD.getTypeSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(QI)) {
- pointer = F->getPointerOperand();
-
- // FreeInsts erase the entire structure
- pointerSize = ~0UL;
- } else if (CallSite::get(QI).getInstruction() != 0) {
- // Call insts need special handling. Check if they can modify our pointer
- AliasAnalysis::ModRefResult MR = AA.getModRefInfo(CallSite::get(QI),
- dependee, dependeeSize);
-
- if (MR != AliasAnalysis::NoModRef) {
- // Loads don't depend on read-only calls
- if (isa<LoadInst>(query) && MR == AliasAnalysis::Ref)
+ }
+
+ // 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<Instruction>(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<DenseMap<BasicBlock*,Value*>::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 (!start && !block) {
- depGraphLocal.insert(std::make_pair(query,
- std::make_pair(QI, true)));
- reverseDep[QI].insert(query);
}
- return QI;
- } else {
- 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 found a pointer, check if it could be the same as our pointer
- if (pointer) {
- AliasAnalysis::AliasResult R = AA.alias(pointer, pointerSize,
- dependee, dependeeSize);
-
- if (R != AliasAnalysis::NoAlias) {
- // May-alias loads don't depend on each other
- if (isa<LoadInst>(query) && isa<LoadInst>(QI) &&
- R == AliasAnalysis::MayAlias)
- 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<PHINode>(PtrInst)) {
+ for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+ BasicBlock *Pred = *PI;
+ Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred);
- if (!start && !block) {
- depGraphLocal.insert(std::make_pair(query,
- std::make_pair(QI, true)));
- reverseDep[QI].insert(query);
+ // 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, 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;
- return QI;
+ // 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<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(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;
- // If we found nothing, return the non-local flag
- if (!start && !block) {
- depGraphLocal.insert(std::make_pair(query,
- std::make_pair(NonLocal, true)));
- reverseDep[NonLocal].insert(query);
+ 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());
}
- return NonLocal;
+ // 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<PointerType>(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.
-void MemoryDependenceAnalysis::removeInstruction(Instruction* rem) {
- // Figure out the new dep for things that currently depend on rem
- Instruction* newDep = NonLocal;
-
- depMapType::iterator depGraphEntry = depGraphLocal.find(rem);
-
- if (depGraphEntry != depGraphLocal.end()) {
- if (depGraphEntry->second.first != NonLocal &&
- depGraphEntry->second.second) {
- // If we have dep info for rem, set them to it
- BasicBlock::iterator RI = depGraphEntry->second.first;
- RI++;
- newDep = RI;
- } else if (depGraphEntry->second.first == NonLocal &&
- depGraphEntry->second.second ) {
- // If we have a confirmed non-local flag, use it
- newDep = NonLocal;
- } else {
- // Otherwise, use the immediate successor of rem
- // NOTE: This is because, when getDependence is called, it will first
- // check the immediate predecessor of what is in the cache.
- BasicBlock::iterator RI = rem;
- RI++;
- newDep = RI;
+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->second.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 (isa<PointerType>(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<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->second.getInst() != RemInst) continue;
+
+ // Convert to a dirty entry for the subsequent instruction.
+ DI->second = 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<void*, 4> &Set = ReversePtrDepIt->second;
+ SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
- SmallPtrSet<Instruction*, 4>& set = reverseDep[rem];
- for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
+ for (SmallPtrSet<void*, 4>::iterator I = Set.begin(), E = Set.end();
I != E; ++I) {
- // Insert the new dependencies
- // Mark it as unconfirmed as long as it is not the non-local flag
- depGraphLocal[*I] = std::make_pair(newDep, !newDep);
+ 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());
}
- reverseDep.erase(rem);
+ ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
+
+ while (!ReversePtrDepsToAdd.empty()) {
+ ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
+ .insert(ReversePtrDepsToAdd.back().second.getOpaqueValue());
+ ReversePtrDepsToAdd.pop_back();
+ }
}
- if (depGraphNonLocal.count(rem)) {
- SmallPtrSet<Instruction*, 4>& set = reverseDepNonLocal[rem];
- for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
- I != E; ++I)
- depGraphNonLocal.erase(*I);
+
+ 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.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");
+ const PerInstNLInfo &INLD = I->second;
+ for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
+ EE = INLD.first.end(); II != EE; ++II)
+ assert(II->second.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");
- reverseDepNonLocal.erase(rem);
+ for (SmallPtrSet<void*, 4>::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");
}
-
- getAnalysis<AliasAnalysis>().deleteValue(rem);
+
}
projects / oota-llvm.git / blobdiff