1 //===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements an analysis that determines, for a given memory
11 // operation, what preceding memory operations it depends on. It builds on
12 // alias analysis information, and tries to provide a lazy, caching interface to
13 // a common kind of alias information query.
15 //===----------------------------------------------------------------------===//
17 #define DEBUG_TYPE "memdep"
18 #include "llvm/Analysis/MemoryDependenceAnalysis.h"
19 #include "llvm/Constants.h"
20 #include "llvm/Instructions.h"
21 #include "llvm/Function.h"
22 #include "llvm/Analysis/AliasAnalysis.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Support/PredIteratorCache.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Target/TargetData.h"
29 STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
30 STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
31 STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
33 STATISTIC(NumCacheNonLocalPtr,
34 "Number of fully cached non-local ptr responses");
35 STATISTIC(NumCacheDirtyNonLocalPtr,
36 "Number of cached, but dirty, non-local ptr responses");
37 STATISTIC(NumUncacheNonLocalPtr,
38 "Number of uncached non-local ptr responses");
39 STATISTIC(NumCacheCompleteNonLocalPtr,
40 "Number of block queries that were completely cached");
42 char MemoryDependenceAnalysis::ID = 0;
44 // Register this pass...
45 static RegisterPass<MemoryDependenceAnalysis> X("memdep",
46 "Memory Dependence Analysis", false, true);
48 MemoryDependenceAnalysis::MemoryDependenceAnalysis()
49 : FunctionPass(&ID), PredCache(0) {
51 MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
54 /// Clean up memory in between runs
55 void MemoryDependenceAnalysis::releaseMemory() {
58 NonLocalPointerDeps.clear();
59 ReverseLocalDeps.clear();
60 ReverseNonLocalDeps.clear();
61 ReverseNonLocalPtrDeps.clear();
67 /// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
69 void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
71 AU.addRequiredTransitive<AliasAnalysis>();
72 AU.addRequiredTransitive<TargetData>();
75 bool MemoryDependenceAnalysis::runOnFunction(Function &) {
76 AA = &getAnalysis<AliasAnalysis>();
77 TD = &getAnalysis<TargetData>();
79 PredCache.reset(new PredIteratorCache());
83 /// RemoveFromReverseMap - This is a helper function that removes Val from
84 /// 'Inst's set in ReverseMap. If the set becomes empty, remove Inst's entry.
85 template <typename KeyTy>
86 static void RemoveFromReverseMap(DenseMap<Instruction*,
87 SmallPtrSet<KeyTy*, 4> > &ReverseMap,
88 Instruction *Inst, KeyTy *Val) {
89 typename DenseMap<Instruction*, SmallPtrSet<KeyTy*, 4> >::iterator
90 InstIt = ReverseMap.find(Inst);
91 assert(InstIt != ReverseMap.end() && "Reverse map out of sync?");
92 bool Found = InstIt->second.erase(Val);
93 assert(Found && "Invalid reverse map!"); Found=Found;
94 if (InstIt->second.empty())
95 ReverseMap.erase(InstIt);
99 /// getCallSiteDependencyFrom - Private helper for finding the local
100 /// dependencies of a call site.
101 MemDepResult MemoryDependenceAnalysis::
102 getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt,
104 // Walk backwards through the block, looking for dependencies
105 while (ScanIt != BB->begin()) {
106 Instruction *Inst = --ScanIt;
108 // If this inst is a memory op, get the pointer it accessed
110 uint64_t PointerSize = 0;
111 if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
112 Pointer = S->getPointerOperand();
113 PointerSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
114 } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
115 Pointer = V->getOperand(0);
116 PointerSize = TD->getTypeStoreSize(V->getType());
117 } else if (FreeInst *F = dyn_cast<FreeInst>(Inst)) {
118 Pointer = F->getPointerOperand();
120 // FreeInsts erase the entire structure
122 } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
123 CallSite InstCS = CallSite::get(Inst);
124 // If these two calls do not interfere, look past it.
125 if (AA->getModRefInfo(CS, InstCS) == AliasAnalysis::NoModRef)
128 // FIXME: If this is a ref/ref result, we should ignore it!
131 // Z = strlen(P); // Z = X
133 // If they interfere, we generally return clobber. However, if they are
134 // calls to the same read-only functions we return Def.
135 if (!AA->onlyReadsMemory(CS) || CS.getCalledFunction() == 0 ||
136 CS.getCalledFunction() != InstCS.getCalledFunction())
137 return MemDepResult::getClobber(Inst);
138 return MemDepResult::getDef(Inst);
140 // Non-memory instruction.
144 if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
145 return MemDepResult::getClobber(Inst);
148 // No dependence found. If this is the entry block of the function, it is a
149 // clobber, otherwise it is non-local.
150 if (BB != &BB->getParent()->getEntryBlock())
151 return MemDepResult::getNonLocal();
152 return MemDepResult::getClobber(ScanIt);
155 /// getPointerDependencyFrom - Return the instruction on which a memory
156 /// location depends. If isLoad is true, this routine ignore may-aliases with
157 /// read-only operations.
158 MemDepResult MemoryDependenceAnalysis::
159 getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
160 BasicBlock::iterator ScanIt, BasicBlock *BB) {
162 // Walk backwards through the basic block, looking for dependencies.
163 while (ScanIt != BB->begin()) {
164 Instruction *Inst = --ScanIt;
166 // Values depend on loads if the pointers are must aliased. This means that
167 // a load depends on another must aliased load from the same value.
168 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
169 Value *Pointer = LI->getPointerOperand();
170 uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
172 // If we found a pointer, check if it could be the same as our pointer.
173 AliasAnalysis::AliasResult R =
174 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
175 if (R == AliasAnalysis::NoAlias)
178 // May-alias loads don't depend on each other without a dependence.
179 if (isLoad && R == AliasAnalysis::MayAlias)
181 // Stores depend on may and must aliased loads, loads depend on must-alias
183 return MemDepResult::getDef(Inst);
186 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
187 Value *Pointer = SI->getPointerOperand();
188 uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
190 // If we found a pointer, check if it could be the same as our pointer.
191 AliasAnalysis::AliasResult R =
192 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
194 if (R == AliasAnalysis::NoAlias)
196 if (R == AliasAnalysis::MayAlias)
197 return MemDepResult::getClobber(Inst);
198 return MemDepResult::getDef(Inst);
201 // If this is an allocation, and if we know that the accessed pointer is to
202 // the allocation, return Def. This means that there is no dependence and
203 // the access can be optimized based on that. For example, a load could
205 if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
206 Value *AccessPtr = MemPtr->getUnderlyingObject();
208 if (AccessPtr == AI ||
209 AA->alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
210 return MemDepResult::getDef(AI);
214 // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
215 // FIXME: If this is a load, we should ignore readonly calls!
216 if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef)
219 // Otherwise, there is a dependence.
220 return MemDepResult::getClobber(Inst);
223 // No dependence found. If this is the entry block of the function, it is a
224 // clobber, otherwise it is non-local.
225 if (BB != &BB->getParent()->getEntryBlock())
226 return MemDepResult::getNonLocal();
227 return MemDepResult::getClobber(ScanIt);
230 /// getDependency - Return the instruction on which a memory operation
232 MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
233 Instruction *ScanPos = QueryInst;
235 // Check for a cached result
236 MemDepResult &LocalCache = LocalDeps[QueryInst];
238 // If the cached entry is non-dirty, just return it. Note that this depends
239 // on MemDepResult's default constructing to 'dirty'.
240 if (!LocalCache.isDirty())
243 // Otherwise, if we have a dirty entry, we know we can start the scan at that
244 // instruction, which may save us some work.
245 if (Instruction *Inst = LocalCache.getInst()) {
248 RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
251 BasicBlock *QueryParent = QueryInst->getParent();
254 uint64_t MemSize = 0;
257 if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
258 // No dependence found. If this is the entry block of the function, it is a
259 // clobber, otherwise it is non-local.
260 if (QueryParent != &QueryParent->getParent()->getEntryBlock())
261 LocalCache = MemDepResult::getNonLocal();
263 LocalCache = MemDepResult::getClobber(QueryInst);
264 } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
265 // If this is a volatile store, don't mess around with it. Just return the
266 // previous instruction as a clobber.
267 if (SI->isVolatile())
268 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
270 MemPtr = SI->getPointerOperand();
271 MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
273 } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
274 // If this is a volatile load, don't mess around with it. Just return the
275 // previous instruction as a clobber.
276 if (LI->isVolatile())
277 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
279 MemPtr = LI->getPointerOperand();
280 MemSize = TD->getTypeStoreSize(LI->getType());
282 } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
283 LocalCache = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
285 } else if (FreeInst *FI = dyn_cast<FreeInst>(QueryInst)) {
286 MemPtr = FI->getPointerOperand();
287 // FreeInsts erase the entire structure, not just a field.
290 // Non-memory instruction.
291 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
294 // If we need to do a pointer scan, make it happen.
296 LocalCache = getPointerDependencyFrom(MemPtr, MemSize,
297 isa<LoadInst>(QueryInst),
298 ScanPos, QueryParent);
300 // Remember the result!
301 if (Instruction *I = LocalCache.getInst())
302 ReverseLocalDeps[I].insert(QueryInst);
307 /// getNonLocalDependency - Perform a full dependency query for the
308 /// specified instruction, returning the set of blocks that the value is
309 /// potentially live across. The returned set of results will include a
310 /// "NonLocal" result for all blocks where the value is live across.
312 /// This method assumes the instruction returns a "nonlocal" dependency
313 /// within its own block.
315 const MemoryDependenceAnalysis::NonLocalDepInfo &
316 MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) {
317 // FIXME: Make this only be for callsites in the future.
318 assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst) ||
319 isa<LoadInst>(QueryInst) || isa<StoreInst>(QueryInst));
320 assert(getDependency(QueryInst).isNonLocal() &&
321 "getNonLocalDependency should only be used on insts with non-local deps!");
322 PerInstNLInfo &CacheP = NonLocalDeps[QueryInst];
323 NonLocalDepInfo &Cache = CacheP.first;
325 /// DirtyBlocks - This is the set of blocks that need to be recomputed. In
326 /// the cached case, this can happen due to instructions being deleted etc. In
327 /// the uncached case, this starts out as the set of predecessors we care
329 SmallVector<BasicBlock*, 32> DirtyBlocks;
331 if (!Cache.empty()) {
332 // Okay, we have a cache entry. If we know it is not dirty, just return it
333 // with no computation.
334 if (!CacheP.second) {
339 // If we already have a partially computed set of results, scan them to
340 // determine what is dirty, seeding our initial DirtyBlocks worklist.
341 for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
343 if (I->second.isDirty())
344 DirtyBlocks.push_back(I->first);
346 // Sort the cache so that we can do fast binary search lookups below.
347 std::sort(Cache.begin(), Cache.end());
349 ++NumCacheDirtyNonLocal;
350 //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
351 // << Cache.size() << " cached: " << *QueryInst;
353 // Seed DirtyBlocks with each of the preds of QueryInst's block.
354 BasicBlock *QueryBB = QueryInst->getParent();
355 for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
356 DirtyBlocks.push_back(*PI);
357 NumUncacheNonLocal++;
360 // Visited checked first, vector in sorted order.
361 SmallPtrSet<BasicBlock*, 64> Visited;
363 unsigned NumSortedEntries = Cache.size();
365 // Iterate while we still have blocks to update.
366 while (!DirtyBlocks.empty()) {
367 BasicBlock *DirtyBB = DirtyBlocks.back();
368 DirtyBlocks.pop_back();
370 // Already processed this block?
371 if (!Visited.insert(DirtyBB))
374 // Do a binary search to see if we already have an entry for this block in
375 // the cache set. If so, find it.
376 NonLocalDepInfo::iterator Entry =
377 std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
378 std::make_pair(DirtyBB, MemDepResult()));
379 if (Entry != Cache.begin() && (&*Entry)[-1].first == DirtyBB)
382 MemDepResult *ExistingResult = 0;
383 if (Entry != Cache.begin()+NumSortedEntries &&
384 Entry->first == DirtyBB) {
385 // If we already have an entry, and if it isn't already dirty, the block
387 if (!Entry->second.isDirty())
390 // Otherwise, remember this slot so we can update the value.
391 ExistingResult = &Entry->second;
394 // If the dirty entry has a pointer, start scanning from it so we don't have
395 // to rescan the entire block.
396 BasicBlock::iterator ScanPos = DirtyBB->end();
397 if (ExistingResult) {
398 if (Instruction *Inst = ExistingResult->getInst()) {
400 // We're removing QueryInst's use of Inst.
401 RemoveFromReverseMap(ReverseNonLocalDeps, Inst, QueryInst);
405 // Find out if this block has a local dependency for QueryInst.
409 uint64_t MemSize = 0;
411 if (ScanPos == DirtyBB->begin()) {
412 // No dependence found. If this is the entry block of the function, it is a
413 // clobber, otherwise it is non-local.
414 if (DirtyBB != &DirtyBB->getParent()->getEntryBlock())
415 Dep = MemDepResult::getNonLocal();
417 Dep = MemDepResult::getClobber(ScanPos);
418 } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
419 // If this is a volatile store, don't mess around with it. Just return the
420 // previous instruction as a clobber.
421 if (SI->isVolatile())
422 Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
424 MemPtr = SI->getPointerOperand();
425 MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
427 } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
428 // If this is a volatile load, don't mess around with it. Just return the
429 // previous instruction as a clobber.
430 if (LI->isVolatile())
431 Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
433 MemPtr = LI->getPointerOperand();
434 MemSize = TD->getTypeStoreSize(LI->getType());
437 assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst));
438 Dep = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
443 Dep = getPointerDependencyFrom(MemPtr, MemSize, isa<LoadInst>(QueryInst),
446 // If we had a dirty entry for the block, update it. Otherwise, just add
449 *ExistingResult = Dep;
451 Cache.push_back(std::make_pair(DirtyBB, Dep));
453 // If the block has a dependency (i.e. it isn't completely transparent to
454 // the value), remember the association!
455 if (!Dep.isNonLocal()) {
456 // Keep the ReverseNonLocalDeps map up to date so we can efficiently
457 // update this when we remove instructions.
458 if (Instruction *Inst = Dep.getInst())
459 ReverseNonLocalDeps[Inst].insert(QueryInst);
462 // If the block *is* completely transparent to the load, we need to check
463 // the predecessors of this block. Add them to our worklist.
464 for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
465 DirtyBlocks.push_back(*PI);
472 /// getNonLocalPointerDependency - Perform a full dependency query for an
473 /// access to the specified (non-volatile) memory location, returning the
474 /// set of instructions that either define or clobber the value.
476 /// This method assumes the pointer has a "NonLocal" dependency within its
479 void MemoryDependenceAnalysis::
480 getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB,
481 SmallVectorImpl<NonLocalDepEntry> &Result) {
482 assert(isa<PointerType>(Pointer->getType()) &&
483 "Can't get pointer deps of a non-pointer!");
486 // We know that the pointer value is live into FromBB find the def/clobbers
487 // from presecessors.
488 const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
489 uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
491 // While we have blocks to analyze, get their values.
492 SmallPtrSet<BasicBlock*, 64> Visited;
493 getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB,
497 /// GetNonLocalInfoForBlock - Compute the memdep value for BB with
498 /// Pointer/PointeeSize using either cached information in Cache or by doing a
499 /// lookup (which may use dirty cache info if available). If we do a lookup,
500 /// add the result to the cache.
501 MemDepResult MemoryDependenceAnalysis::
502 GetNonLocalInfoForBlock(Value *Pointer, uint64_t PointeeSize,
503 bool isLoad, BasicBlock *BB,
504 NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
506 // Do a binary search to see if we already have an entry for this block in
507 // the cache set. If so, find it.
508 NonLocalDepInfo::iterator Entry =
509 std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
510 std::make_pair(BB, MemDepResult()));
511 if (Entry != Cache->begin() && (&*Entry)[-1].first == BB)
514 MemDepResult *ExistingResult = 0;
515 if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
516 ExistingResult = &Entry->second;
518 // If we have a cached entry, and it is non-dirty, use it as the value for
520 if (ExistingResult && !ExistingResult->isDirty()) {
521 ++NumCacheNonLocalPtr;
522 return *ExistingResult;
525 // Otherwise, we have to scan for the value. If we have a dirty cache
526 // entry, start scanning from its position, otherwise we scan from the end
528 BasicBlock::iterator ScanPos = BB->end();
529 if (ExistingResult && ExistingResult->getInst()) {
530 assert(ExistingResult->getInst()->getParent() == BB &&
531 "Instruction invalidated?");
532 ++NumCacheDirtyNonLocalPtr;
533 ScanPos = ExistingResult->getInst();
535 // Eliminating the dirty entry from 'Cache', so update the reverse info.
536 ValueIsLoadPair CacheKey(Pointer, isLoad);
537 RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos,
538 CacheKey.getOpaqueValue());
540 ++NumUncacheNonLocalPtr;
543 // Scan the block for the dependency.
544 MemDepResult Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad,
547 // If we had a dirty entry for the block, update it. Otherwise, just add
550 *ExistingResult = Dep;
552 Cache->push_back(std::make_pair(BB, Dep));
554 // If the block has a dependency (i.e. it isn't completely transparent to
555 // the value), remember the reverse association because we just added it
557 if (Dep.isNonLocal())
560 // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
561 // update MemDep when we remove instructions.
562 Instruction *Inst = Dep.getInst();
563 assert(Inst && "Didn't depend on anything?");
564 ValueIsLoadPair CacheKey(Pointer, isLoad);
565 ReverseNonLocalPtrDeps[Inst].insert(CacheKey.getOpaqueValue());
570 /// getNonLocalPointerDepFromBB -
571 void MemoryDependenceAnalysis::
572 getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
573 bool isLoad, BasicBlock *StartBB,
574 SmallVectorImpl<NonLocalDepEntry> &Result,
575 SmallPtrSet<BasicBlock*, 64> &Visited) {
576 // Look up the cached info for Pointer.
577 ValueIsLoadPair CacheKey(Pointer, isLoad);
579 std::pair<BasicBlock*, NonLocalDepInfo> &CacheInfo =
580 NonLocalPointerDeps[CacheKey];
581 NonLocalDepInfo *Cache = &CacheInfo.second;
583 // If we have valid cached information for exactly the block we are
584 // investigating, just return it with no recomputation.
585 if (CacheInfo.first == StartBB) {
586 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
588 if (!I->second.isNonLocal())
589 Result.push_back(*I);
590 ++NumCacheCompleteNonLocalPtr;
594 // Otherwise, either this is a new block, a block with an invalid cache
595 // pointer or one that we're about to invalidate by putting more info into it
596 // than its valid cache info. If empty, the result will be valid cache info,
597 // otherwise it isn't.
598 CacheInfo.first = Cache->empty() ? StartBB : 0;
600 SmallVector<BasicBlock*, 32> Worklist;
601 Worklist.push_back(StartBB);
603 // Keep track of the entries that we know are sorted. Previously cached
604 // entries will all be sorted. The entries we add we only sort on demand (we
605 // don't insert every element into its sorted position). We know that we
606 // won't get any reuse from currently inserted values, because we don't
607 // revisit blocks after we insert info for them.
608 unsigned NumSortedEntries = Cache->size();
610 // SkipFirstBlock - If this is the very first block that we're processing, we
611 // don't want to scan or think about its body, because the client was supposed
612 // to do a local dependence query. Instead, just start processing it by
613 // adding its predecessors to the worklist and iterating.
614 bool SkipFirstBlock = Visited.empty();
616 while (!Worklist.empty()) {
617 BasicBlock *BB = Worklist.pop_back_val();
619 // Skip the first block if we have it.
620 if (SkipFirstBlock) {
621 SkipFirstBlock = false;
623 // Analyze the dependency of *Pointer in FromBB. See if we already have
625 if (!Visited.insert(BB))
628 // Get the dependency info for Pointer in BB. If we have cached
629 // information, we will use it, otherwise we compute it.
630 MemDepResult Dep = GetNonLocalInfoForBlock(Pointer, PointeeSize, isLoad,
631 BB, Cache, NumSortedEntries);
633 // If we got a Def or Clobber, add this to the list of results.
634 if (!Dep.isNonLocal()) {
635 Result.push_back(NonLocalDepEntry(BB, Dep));
640 // Otherwise, we have to process all the predecessors of this block to scan
642 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
643 // TODO: PHI TRANSLATE.
644 Worklist.push_back(*PI);
648 // Okay, we're done now. If we added new values to the cache, re-sort it.
649 switch (Cache->size()-NumSortedEntries) {
651 // done, no new entries.
654 // Two new entries, insert the last one into place.
655 NonLocalDepEntry Val = Cache->back();
657 NonLocalDepInfo::iterator Entry =
658 std::upper_bound(Cache->begin(), Cache->end()-1, Val);
659 Cache->insert(Entry, Val);
663 // One new entry, Just insert the new value at the appropriate position.
664 NonLocalDepEntry Val = Cache->back();
666 NonLocalDepInfo::iterator Entry =
667 std::upper_bound(Cache->begin(), Cache->end(), Val);
668 Cache->insert(Entry, Val);
672 // Added many values, do a full scale sort.
673 std::sort(Cache->begin(), Cache->end());
677 /// RemoveCachedNonLocalPointerDependencies - If P exists in
678 /// CachedNonLocalPointerInfo, remove it.
679 void MemoryDependenceAnalysis::
680 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
681 CachedNonLocalPointerInfo::iterator It =
682 NonLocalPointerDeps.find(P);
683 if (It == NonLocalPointerDeps.end()) return;
685 // Remove all of the entries in the BB->val map. This involves removing
686 // instructions from the reverse map.
687 NonLocalDepInfo &PInfo = It->second.second;
689 for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
690 Instruction *Target = PInfo[i].second.getInst();
691 if (Target == 0) continue; // Ignore non-local dep results.
692 assert(Target->getParent() == PInfo[i].first && Target != P.getPointer());
694 // Eliminating the dirty entry from 'Cache', so update the reverse info.
695 RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P.getOpaqueValue());
698 // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
699 NonLocalPointerDeps.erase(It);
703 /// removeInstruction - Remove an instruction from the dependence analysis,
704 /// updating the dependence of instructions that previously depended on it.
705 /// This method attempts to keep the cache coherent using the reverse map.
706 void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
707 // Walk through the Non-local dependencies, removing this one as the value
708 // for any cached queries.
709 NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
710 if (NLDI != NonLocalDeps.end()) {
711 NonLocalDepInfo &BlockMap = NLDI->second.first;
712 for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
714 if (Instruction *Inst = DI->second.getInst())
715 RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
716 NonLocalDeps.erase(NLDI);
719 // If we have a cached local dependence query for this instruction, remove it.
721 LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
722 if (LocalDepEntry != LocalDeps.end()) {
723 // Remove us from DepInst's reverse set now that the local dep info is gone.
724 if (Instruction *Inst = LocalDepEntry->second.getInst())
725 RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
727 // Remove this local dependency info.
728 LocalDeps.erase(LocalDepEntry);
731 // If we have any cached pointer dependencies on this instruction, remove
732 // them. If the instruction has non-pointer type, then it can't be a pointer
735 // Remove it from both the load info and the store info. The instruction
736 // can't be in either of these maps if it is non-pointer.
737 if (isa<PointerType>(RemInst->getType())) {
738 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
739 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
742 // Loop over all of the things that depend on the instruction we're removing.
744 SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
746 // If we find RemInst as a clobber or Def in any of the maps for other values,
747 // we need to replace its entry with a dirty version of the instruction after
748 // it. If RemInst is a terminator, we use a null dirty value.
750 // Using a dirty version of the instruction after RemInst saves having to scan
751 // the entire block to get to this point.
752 MemDepResult NewDirtyVal;
753 if (!RemInst->isTerminator())
754 NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
756 ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
757 if (ReverseDepIt != ReverseLocalDeps.end()) {
758 SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
759 // RemInst can't be the terminator if it has local stuff depending on it.
760 assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
761 "Nothing can locally depend on a terminator");
763 for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
764 E = ReverseDeps.end(); I != E; ++I) {
765 Instruction *InstDependingOnRemInst = *I;
766 assert(InstDependingOnRemInst != RemInst &&
767 "Already removed our local dep info");
769 LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
771 // Make sure to remember that new things depend on NewDepInst.
772 assert(NewDirtyVal.getInst() && "There is no way something else can have "
773 "a local dep on this if it is a terminator!");
774 ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(),
775 InstDependingOnRemInst));
778 ReverseLocalDeps.erase(ReverseDepIt);
780 // Add new reverse deps after scanning the set, to avoid invalidating the
781 // 'ReverseDeps' reference.
782 while (!ReverseDepsToAdd.empty()) {
783 ReverseLocalDeps[ReverseDepsToAdd.back().first]
784 .insert(ReverseDepsToAdd.back().second);
785 ReverseDepsToAdd.pop_back();
789 ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
790 if (ReverseDepIt != ReverseNonLocalDeps.end()) {
791 SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
792 for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
794 assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
796 PerInstNLInfo &INLD = NonLocalDeps[*I];
797 // The information is now dirty!
800 for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
801 DE = INLD.first.end(); DI != DE; ++DI) {
802 if (DI->second.getInst() != RemInst) continue;
804 // Convert to a dirty entry for the subsequent instruction.
805 DI->second = NewDirtyVal;
807 if (Instruction *NextI = NewDirtyVal.getInst())
808 ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
812 ReverseNonLocalDeps.erase(ReverseDepIt);
814 // Add new reverse deps after scanning the set, to avoid invalidating 'Set'
815 while (!ReverseDepsToAdd.empty()) {
816 ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
817 .insert(ReverseDepsToAdd.back().second);
818 ReverseDepsToAdd.pop_back();
822 // If the instruction is in ReverseNonLocalPtrDeps then it appears as a
823 // value in the NonLocalPointerDeps info.
824 ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
825 ReverseNonLocalPtrDeps.find(RemInst);
826 if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
827 SmallPtrSet<void*, 4> &Set = ReversePtrDepIt->second;
828 SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
830 for (SmallPtrSet<void*, 4>::iterator I = Set.begin(), E = Set.end();
833 P.setFromOpaqueValue(*I);
834 assert(P.getPointer() != RemInst &&
835 "Already removed NonLocalPointerDeps info for RemInst");
837 NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].second;
839 // The cache is not valid for any specific block anymore.
840 NonLocalPointerDeps[P].first = 0;
842 // Update any entries for RemInst to use the instruction after it.
843 for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
845 if (DI->second.getInst() != RemInst) continue;
847 // Convert to a dirty entry for the subsequent instruction.
848 DI->second = NewDirtyVal;
850 if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
851 ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
855 ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
857 while (!ReversePtrDepsToAdd.empty()) {
858 ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
859 .insert(ReversePtrDepsToAdd.back().second.getOpaqueValue());
860 ReversePtrDepsToAdd.pop_back();
865 assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
866 AA->deleteValue(RemInst);
867 DEBUG(verifyRemoved(RemInst));
870 /// verifyRemoved - Verify that the specified instruction does not occur
871 /// in our internal data structures.
872 void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
873 for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
874 E = LocalDeps.end(); I != E; ++I) {
875 assert(I->first != D && "Inst occurs in data structures");
876 assert(I->second.getInst() != D &&
877 "Inst occurs in data structures");
880 for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
881 E = NonLocalPointerDeps.end(); I != E; ++I) {
882 assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
883 const NonLocalDepInfo &Val = I->second.second;
884 for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
886 assert(II->second.getInst() != D && "Inst occurs as NLPD value");
889 for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
890 E = NonLocalDeps.end(); I != E; ++I) {
891 assert(I->first != D && "Inst occurs in data structures");
892 const PerInstNLInfo &INLD = I->second;
893 for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
894 EE = INLD.first.end(); II != EE; ++II)
895 assert(II->second.getInst() != D && "Inst occurs in data structures");
898 for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
899 E = ReverseLocalDeps.end(); I != E; ++I) {
900 assert(I->first != D && "Inst occurs in data structures");
901 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
902 EE = I->second.end(); II != EE; ++II)
903 assert(*II != D && "Inst occurs in data structures");
906 for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
907 E = ReverseNonLocalDeps.end();
909 assert(I->first != D && "Inst occurs in data structures");
910 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
911 EE = I->second.end(); II != EE; ++II)
912 assert(*II != D && "Inst occurs in data structures");
915 for (ReverseNonLocalPtrDepTy::const_iterator
916 I = ReverseNonLocalPtrDeps.begin(),
917 E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
918 assert(I->first != D && "Inst occurs in rev NLPD map");
920 for (SmallPtrSet<void*, 4>::const_iterator II = I->second.begin(),
921 E = I->second.end(); II != E; ++II)
922 assert(*II != ValueIsLoadPair(D, false).getOpaqueValue() &&
923 *II != ValueIsLoadPair(D, true).getOpaqueValue() &&
924 "Inst occurs in ReverseNonLocalPtrDeps map");