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/CFG.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");
40 char MemoryDependenceAnalysis::ID = 0;
42 // Register this pass...
43 static RegisterPass<MemoryDependenceAnalysis> X("memdep",
44 "Memory Dependence Analysis", false, true);
46 /// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
48 void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
50 AU.addRequiredTransitive<AliasAnalysis>();
51 AU.addRequiredTransitive<TargetData>();
54 bool MemoryDependenceAnalysis::runOnFunction(Function &) {
55 AA = &getAnalysis<AliasAnalysis>();
56 TD = &getAnalysis<TargetData>();
61 /// getCallSiteDependencyFrom - Private helper for finding the local
62 /// dependencies of a call site.
63 MemDepResult MemoryDependenceAnalysis::
64 getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt,
66 // Walk backwards through the block, looking for dependencies
67 while (ScanIt != BB->begin()) {
68 Instruction *Inst = --ScanIt;
70 // If this inst is a memory op, get the pointer it accessed
72 uint64_t PointerSize = 0;
73 if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
74 Pointer = S->getPointerOperand();
75 PointerSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
76 } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
77 Pointer = V->getOperand(0);
78 PointerSize = TD->getTypeStoreSize(V->getType());
79 } else if (FreeInst *F = dyn_cast<FreeInst>(Inst)) {
80 Pointer = F->getPointerOperand();
82 // FreeInsts erase the entire structure
84 } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
85 CallSite InstCS = CallSite::get(Inst);
86 // If these two calls do not interfere, look past it.
87 if (AA->getModRefInfo(CS, InstCS) == AliasAnalysis::NoModRef)
90 // FIXME: If this is a ref/ref result, we should ignore it!
93 // Z = strlen(P); // Z = X
95 // If they interfere, we generally return clobber. However, if they are
96 // calls to the same read-only functions we return Def.
97 if (!AA->onlyReadsMemory(CS) || CS.getCalledFunction() == 0 ||
98 CS.getCalledFunction() != InstCS.getCalledFunction())
99 return MemDepResult::getClobber(Inst);
100 return MemDepResult::getDef(Inst);
102 // Non-memory instruction.
106 if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
107 return MemDepResult::getClobber(Inst);
110 // No dependence found. If this is the entry block of the function, it is a
111 // clobber, otherwise it is non-local.
112 if (BB != &BB->getParent()->getEntryBlock())
113 return MemDepResult::getNonLocal();
114 return MemDepResult::getClobber(ScanIt);
117 /// getPointerDependencyFrom - Return the instruction on which a memory
118 /// location depends. If isLoad is true, this routine ignore may-aliases with
119 /// read-only operations.
120 MemDepResult MemoryDependenceAnalysis::
121 getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
122 BasicBlock::iterator ScanIt, BasicBlock *BB) {
124 // Walk backwards through the basic block, looking for dependencies.
125 while (ScanIt != BB->begin()) {
126 Instruction *Inst = --ScanIt;
128 // Values depend on loads if the pointers are must aliased. This means that
129 // a load depends on another must aliased load from the same value.
130 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
131 Value *Pointer = LI->getPointerOperand();
132 uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
134 // If we found a pointer, check if it could be the same as our pointer.
135 AliasAnalysis::AliasResult R =
136 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
137 if (R == AliasAnalysis::NoAlias)
140 // May-alias loads don't depend on each other without a dependence.
141 if (isLoad && R == AliasAnalysis::MayAlias)
143 // Stores depend on may and must aliased loads, loads depend on must-alias
145 return MemDepResult::getDef(Inst);
148 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
149 Value *Pointer = SI->getPointerOperand();
150 uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
152 // If we found a pointer, check if it could be the same as our pointer.
153 AliasAnalysis::AliasResult R =
154 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
156 if (R == AliasAnalysis::NoAlias)
158 if (R == AliasAnalysis::MayAlias)
159 return MemDepResult::getClobber(Inst);
160 return MemDepResult::getDef(Inst);
163 // If this is an allocation, and if we know that the accessed pointer is to
164 // the allocation, return Def. This means that there is no dependence and
165 // the access can be optimized based on that. For example, a load could
167 if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
168 Value *AccessPtr = MemPtr->getUnderlyingObject();
170 if (AccessPtr == AI ||
171 AA->alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
172 return MemDepResult::getDef(AI);
176 // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
177 // FIXME: If this is a load, we should ignore readonly calls!
178 if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef)
181 // Otherwise, there is a dependence.
182 return MemDepResult::getClobber(Inst);
185 // No dependence found. If this is the entry block of the function, it is a
186 // clobber, otherwise it is non-local.
187 if (BB != &BB->getParent()->getEntryBlock())
188 return MemDepResult::getNonLocal();
189 return MemDepResult::getClobber(ScanIt);
192 /// getDependency - Return the instruction on which a memory operation
194 MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
195 Instruction *ScanPos = QueryInst;
197 // Check for a cached result
198 MemDepResult &LocalCache = LocalDeps[QueryInst];
200 // If the cached entry is non-dirty, just return it. Note that this depends
201 // on MemDepResult's default constructing to 'dirty'.
202 if (!LocalCache.isDirty())
205 // Otherwise, if we have a dirty entry, we know we can start the scan at that
206 // instruction, which may save us some work.
207 if (Instruction *Inst = LocalCache.getInst()) {
210 SmallPtrSet<Instruction*, 4> &InstMap = ReverseLocalDeps[Inst];
211 bool Found = InstMap.erase(QueryInst);
212 assert(Found && "Invalid reverse map!"); Found=Found;
214 // FIXME: use an iterator to avoid looking up inst again.
215 ReverseLocalDeps.erase(Inst);
218 BasicBlock *QueryParent = QueryInst->getParent();
221 uint64_t MemSize = 0;
224 if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
225 // No dependence found. If this is the entry block of the function, it is a
226 // clobber, otherwise it is non-local.
227 if (QueryParent != &QueryParent->getParent()->getEntryBlock())
228 LocalCache = MemDepResult::getNonLocal();
230 LocalCache = MemDepResult::getClobber(QueryInst);
231 } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
232 // If this is a volatile store, don't mess around with it. Just return the
233 // previous instruction as a clobber.
234 if (SI->isVolatile())
235 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
237 MemPtr = SI->getPointerOperand();
238 MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
240 } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
241 // If this is a volatile load, don't mess around with it. Just return the
242 // previous instruction as a clobber.
243 if (LI->isVolatile())
244 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
246 MemPtr = LI->getPointerOperand();
247 MemSize = TD->getTypeStoreSize(LI->getType());
249 } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
250 LocalCache = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
252 } else if (FreeInst *FI = dyn_cast<FreeInst>(QueryInst)) {
253 MemPtr = FI->getPointerOperand();
254 // FreeInsts erase the entire structure, not just a field.
257 // Non-memory instruction.
258 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
261 // If we need to do a pointer scan, make it happen.
263 LocalCache = getPointerDependencyFrom(MemPtr, MemSize,
264 isa<LoadInst>(QueryInst),
265 ScanPos, QueryParent);
267 // Remember the result!
268 if (Instruction *I = LocalCache.getInst())
269 ReverseLocalDeps[I].insert(QueryInst);
274 /// getNonLocalDependency - Perform a full dependency query for the
275 /// specified instruction, returning the set of blocks that the value is
276 /// potentially live across. The returned set of results will include a
277 /// "NonLocal" result for all blocks where the value is live across.
279 /// This method assumes the instruction returns a "nonlocal" dependency
280 /// within its own block.
282 const MemoryDependenceAnalysis::NonLocalDepInfo &
283 MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) {
284 // FIXME: Make this only be for callsites in the future.
285 assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst) ||
286 isa<LoadInst>(QueryInst) || isa<StoreInst>(QueryInst));
287 assert(getDependency(QueryInst).isNonLocal() &&
288 "getNonLocalDependency should only be used on insts with non-local deps!");
289 PerInstNLInfo &CacheP = NonLocalDeps[QueryInst];
290 NonLocalDepInfo &Cache = CacheP.first;
292 /// DirtyBlocks - This is the set of blocks that need to be recomputed. In
293 /// the cached case, this can happen due to instructions being deleted etc. In
294 /// the uncached case, this starts out as the set of predecessors we care
296 SmallVector<BasicBlock*, 32> DirtyBlocks;
298 if (!Cache.empty()) {
299 // Okay, we have a cache entry. If we know it is not dirty, just return it
300 // with no computation.
301 if (!CacheP.second) {
306 // If we already have a partially computed set of results, scan them to
307 // determine what is dirty, seeding our initial DirtyBlocks worklist.
308 for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
310 if (I->second.isDirty())
311 DirtyBlocks.push_back(I->first);
313 // Sort the cache so that we can do fast binary search lookups below.
314 std::sort(Cache.begin(), Cache.end());
316 ++NumCacheDirtyNonLocal;
317 //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
318 // << Cache.size() << " cached: " << *QueryInst;
320 // Seed DirtyBlocks with each of the preds of QueryInst's block.
321 BasicBlock *QueryBB = QueryInst->getParent();
322 DirtyBlocks.append(pred_begin(QueryBB), pred_end(QueryBB));
323 NumUncacheNonLocal++;
326 // Visited checked first, vector in sorted order.
327 SmallPtrSet<BasicBlock*, 64> Visited;
329 unsigned NumSortedEntries = Cache.size();
331 // Iterate while we still have blocks to update.
332 while (!DirtyBlocks.empty()) {
333 BasicBlock *DirtyBB = DirtyBlocks.back();
334 DirtyBlocks.pop_back();
336 // Already processed this block?
337 if (!Visited.insert(DirtyBB))
340 // Do a binary search to see if we already have an entry for this block in
341 // the cache set. If so, find it.
342 NonLocalDepInfo::iterator Entry =
343 std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
344 std::make_pair(DirtyBB, MemDepResult()));
345 if (Entry != Cache.begin() && (&*Entry)[-1].first == DirtyBB)
348 MemDepResult *ExistingResult = 0;
349 if (Entry != Cache.begin()+NumSortedEntries &&
350 Entry->first == DirtyBB) {
351 // If we already have an entry, and if it isn't already dirty, the block
353 if (!Entry->second.isDirty())
356 // Otherwise, remember this slot so we can update the value.
357 ExistingResult = &Entry->second;
360 // If the dirty entry has a pointer, start scanning from it so we don't have
361 // to rescan the entire block.
362 BasicBlock::iterator ScanPos = DirtyBB->end();
363 if (ExistingResult) {
364 if (Instruction *Inst = ExistingResult->getInst()) {
367 // We're removing QueryInst's use of Inst.
368 SmallPtrSet<Instruction*, 4> &InstMap = ReverseNonLocalDeps[Inst];
369 bool Found = InstMap.erase(QueryInst);
370 assert(Found && "Invalid reverse map!"); Found=Found;
371 // FIXME: Use an iterator to avoid looking up inst again.
372 if (InstMap.empty()) ReverseNonLocalDeps.erase(Inst);
376 // Find out if this block has a local dependency for QueryInst.
380 uint64_t MemSize = 0;
382 if (ScanPos == DirtyBB->begin()) {
383 // No dependence found. If this is the entry block of the function, it is a
384 // clobber, otherwise it is non-local.
385 if (DirtyBB != &DirtyBB->getParent()->getEntryBlock())
386 Dep = MemDepResult::getNonLocal();
388 Dep = MemDepResult::getClobber(ScanPos);
389 } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
390 // If this is a volatile store, don't mess around with it. Just return the
391 // previous instruction as a clobber.
392 if (SI->isVolatile())
393 Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
395 MemPtr = SI->getPointerOperand();
396 MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
398 } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
399 // If this is a volatile load, don't mess around with it. Just return the
400 // previous instruction as a clobber.
401 if (LI->isVolatile())
402 Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
404 MemPtr = LI->getPointerOperand();
405 MemSize = TD->getTypeStoreSize(LI->getType());
408 assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst));
409 Dep = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
414 Dep = getPointerDependencyFrom(MemPtr, MemSize, isa<LoadInst>(QueryInst),
417 // If we had a dirty entry for the block, update it. Otherwise, just add
420 *ExistingResult = Dep;
422 Cache.push_back(std::make_pair(DirtyBB, Dep));
424 // If the block has a dependency (i.e. it isn't completely transparent to
425 // the value), remember the association!
426 if (!Dep.isNonLocal()) {
427 // Keep the ReverseNonLocalDeps map up to date so we can efficiently
428 // update this when we remove instructions.
429 if (Instruction *Inst = Dep.getInst())
430 ReverseNonLocalDeps[Inst].insert(QueryInst);
433 // If the block *is* completely transparent to the load, we need to check
434 // the predecessors of this block. Add them to our worklist.
435 DirtyBlocks.append(pred_begin(DirtyBB), pred_end(DirtyBB));
442 /// getNonLocalPointerDependency - Perform a full dependency query for an
443 /// access to the specified (non-volatile) memory location, returning the
444 /// set of instructions that either define or clobber the value.
446 /// This method assumes the pointer has a "NonLocal" dependency within its
449 void MemoryDependenceAnalysis::
450 getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB,
451 SmallVectorImpl<NonLocalDepEntry> &Result) {
454 // We know that the pointer value is live into FromBB find the def/clobbers
455 // from presecessors.
456 const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
457 uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
459 // While we have blocks to analyze, get their values.
460 SmallPtrSet<BasicBlock*, 64> Visited;
462 for (pred_iterator PI = pred_begin(FromBB), E = pred_end(FromBB); PI != E;
464 // TODO: PHI TRANSLATE.
465 getNonLocalPointerDepInternal(Pointer, PointeeSize, isLoad, *PI,
470 void MemoryDependenceAnalysis::
471 getNonLocalPointerDepInternal(Value *Pointer, uint64_t PointeeSize,
472 bool isLoad, BasicBlock *StartBB,
473 SmallVectorImpl<NonLocalDepEntry> &Result,
474 SmallPtrSet<BasicBlock*, 64> &Visited) {
475 SmallVector<BasicBlock*, 32> Worklist;
476 Worklist.push_back(StartBB);
478 // Look up the cached info for Pointer.
479 ValueIsLoadPair CacheKey(Pointer, isLoad);
480 NonLocalDepInfo *Cache = &NonLocalPointerDeps[CacheKey];
482 // Keep track of the entries that we know are sorted. Previously cached
483 // entries will all be sorted. The entries we add we only sort on demand (we
484 // don't insert every element into its sorted position). We know that we
485 // won't get any reuse from currently inserted values, because we don't
486 // revisit blocks after we insert info for them.
487 unsigned NumSortedEntries = Cache->size();
489 while (!Worklist.empty()) {
490 BasicBlock *BB = Worklist.pop_back_val();
492 // Analyze the dependency of *Pointer in FromBB. See if we already have
494 if (!Visited.insert(BB))
497 // Get the dependency info for Pointer in BB. If we have cached
498 // information, we will use it, otherwise we compute it.
500 // Do a binary search to see if we already have an entry for this block in
501 // the cache set. If so, find it.
502 NonLocalDepInfo::iterator Entry =
503 std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
504 std::make_pair(BB, MemDepResult()));
505 if (Entry != Cache->begin() && (&*Entry)[-1].first == BB)
508 MemDepResult *ExistingResult = 0;
509 if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
510 ExistingResult = &Entry->second;
512 // If we have a cached entry, and it is non-dirty, use it as the value for
515 if (ExistingResult && !ExistingResult->isDirty()) {
516 Dep = *ExistingResult;
517 ++NumCacheNonLocalPtr;
519 // Otherwise, we have to scan for the value. If we have a dirty cache
520 // entry, start scanning from its position, otherwise we scan from the end
522 BasicBlock::iterator ScanPos = BB->end();
523 if (ExistingResult && ExistingResult->getInst()) {
524 assert(ExistingResult->getInst()->getParent() == BB &&
525 "Instruction invalidated?");
526 ++NumCacheDirtyNonLocalPtr;
527 ScanPos = ExistingResult->getInst();
529 // Eliminating the dirty entry from 'Cache', so update the reverse info.
530 SmallPtrSet<void *, 4> &InstMap = ReverseNonLocalPtrDeps[ScanPos];
531 bool Contained = InstMap.erase(CacheKey.getOpaqueValue());
532 assert(Contained && "Invalid cache entry"); Contained=Contained;
533 // FIXME: Use an iterator to avoid a repeated lookup in ".erase".
534 if (InstMap.empty()) ReverseNonLocalPtrDeps.erase(ScanPos);
536 ++NumUncacheNonLocalPtr;
539 // Scan the block for the dependency.
540 Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad, ScanPos, BB);
542 // If we had a dirty entry for the block, update it. Otherwise, just add
545 *ExistingResult = Dep;
547 Cache->push_back(std::make_pair(BB, Dep));
549 // If the block has a dependency (i.e. it isn't completely transparent to
550 // the value), remember the reverse association because we just added it
552 if (!Dep.isNonLocal()) {
553 // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
554 // update MemDep when we remove instructions.
555 Instruction *Inst = Dep.getInst();
556 assert(Inst && "Didn't depend on anything?");
557 ReverseNonLocalPtrDeps[Inst].insert(CacheKey.getOpaqueValue());
561 // If we got a Def or Clobber, add this to the list of results.
562 if (!Dep.isNonLocal()) {
563 Result.push_back(NonLocalDepEntry(BB, Dep));
567 // Otherwise, we have to process all the predecessors of this block to scan
569 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
570 // TODO: PHI TRANSLATE.
571 Worklist.push_back(*PI);
575 // If we computed new values, re-sort Cache.
576 if (NumSortedEntries != Cache->size())
577 std::sort(Cache->begin(), Cache->end());
580 /// RemoveCachedNonLocalPointerDependencies - If P exists in
581 /// CachedNonLocalPointerInfo, remove it.
582 void MemoryDependenceAnalysis::
583 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
584 CachedNonLocalPointerInfo::iterator It =
585 NonLocalPointerDeps.find(P);
586 if (It == NonLocalPointerDeps.end()) return;
588 // Remove all of the entries in the BB->val map. This involves removing
589 // instructions from the reverse map.
590 NonLocalDepInfo &PInfo = It->second;
592 for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
593 Instruction *Target = PInfo[i].second.getInst();
594 if (Target == 0) continue; // Ignore non-local dep results.
595 assert(Target->getParent() == PInfo[i].first && Target != P.getPointer());
597 // Eliminating the dirty entry from 'Cache', so update the reverse info.
598 SmallPtrSet<void *, 4> &InstMap = ReverseNonLocalPtrDeps[Target];
599 bool Contained = InstMap.erase(P.getOpaqueValue());
600 assert(Contained && "Invalid cache entry"); Contained=Contained;
602 // FIXME: Use an iterator to avoid a repeated lookup in ".erase".
603 if (InstMap.empty()) ReverseNonLocalPtrDeps.erase(Target);
606 // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
607 NonLocalPointerDeps.erase(It);
611 /// removeInstruction - Remove an instruction from the dependence analysis,
612 /// updating the dependence of instructions that previously depended on it.
613 /// This method attempts to keep the cache coherent using the reverse map.
614 void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
615 // Walk through the Non-local dependencies, removing this one as the value
616 // for any cached queries.
617 NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
618 if (NLDI != NonLocalDeps.end()) {
619 NonLocalDepInfo &BlockMap = NLDI->second.first;
620 for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
622 if (Instruction *Inst = DI->second.getInst())
623 ReverseNonLocalDeps[Inst].erase(RemInst);
624 NonLocalDeps.erase(NLDI);
627 // If we have a cached local dependence query for this instruction, remove it.
629 LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
630 if (LocalDepEntry != LocalDeps.end()) {
631 // Remove us from DepInst's reverse set now that the local dep info is gone.
632 if (Instruction *Inst = LocalDepEntry->second.getInst()) {
633 SmallPtrSet<Instruction*, 4> &RLD = ReverseLocalDeps[Inst];
634 bool Found = RLD.erase(RemInst);
635 assert(Found && "Invalid reverse map!"); Found=Found;
636 // FIXME: Use an iterator to avoid looking up Inst again.
638 ReverseLocalDeps.erase(Inst);
641 // Remove this local dependency info.
642 LocalDeps.erase(LocalDepEntry);
645 // If we have any cached pointer dependencies on this instruction, remove
646 // them. If the instruction has non-pointer type, then it can't be a pointer
649 // Remove it from both the load info and the store info. The instruction
650 // can't be in either of these maps if it is non-pointer.
651 if (isa<PointerType>(RemInst->getType())) {
652 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
653 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
656 // Loop over all of the things that depend on the instruction we're removing.
658 SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
660 ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
661 if (ReverseDepIt != ReverseLocalDeps.end()) {
662 SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
663 // RemInst can't be the terminator if it has local stuff depending on it.
664 assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
665 "Nothing can locally depend on a terminator");
667 // Anything that was locally dependent on RemInst is now going to be
668 // dependent on the instruction after RemInst. It will have the dirty flag
669 // set so it will rescan. This saves having to scan the entire block to get
671 Instruction *NewDepInst = ++BasicBlock::iterator(RemInst);
673 for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
674 E = ReverseDeps.end(); I != E; ++I) {
675 Instruction *InstDependingOnRemInst = *I;
676 assert(InstDependingOnRemInst != RemInst &&
677 "Already removed our local dep info");
679 LocalDeps[InstDependingOnRemInst] = MemDepResult::getDirty(NewDepInst);
681 // Make sure to remember that new things depend on NewDepInst.
682 ReverseDepsToAdd.push_back(std::make_pair(NewDepInst,
683 InstDependingOnRemInst));
686 ReverseLocalDeps.erase(ReverseDepIt);
688 // Add new reverse deps after scanning the set, to avoid invalidating the
689 // 'ReverseDeps' reference.
690 while (!ReverseDepsToAdd.empty()) {
691 ReverseLocalDeps[ReverseDepsToAdd.back().first]
692 .insert(ReverseDepsToAdd.back().second);
693 ReverseDepsToAdd.pop_back();
697 ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
698 if (ReverseDepIt != ReverseNonLocalDeps.end()) {
699 SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
700 for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
702 assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
704 PerInstNLInfo &INLD = NonLocalDeps[*I];
705 // The information is now dirty!
708 for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
709 DE = INLD.first.end(); DI != DE; ++DI) {
710 if (DI->second.getInst() != RemInst) continue;
712 // Convert to a dirty entry for the subsequent instruction.
713 Instruction *NextI = 0;
714 if (!RemInst->isTerminator()) {
715 NextI = ++BasicBlock::iterator(RemInst);
716 ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
718 DI->second = MemDepResult::getDirty(NextI);
722 ReverseNonLocalDeps.erase(ReverseDepIt);
724 // Add new reverse deps after scanning the set, to avoid invalidating 'Set'
725 while (!ReverseDepsToAdd.empty()) {
726 ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
727 .insert(ReverseDepsToAdd.back().second);
728 ReverseDepsToAdd.pop_back();
732 // If the instruction is in ReverseNonLocalPtrDeps then it appears as a
733 // value in the NonLocalPointerDeps info.
734 ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
735 ReverseNonLocalPtrDeps.find(RemInst);
736 if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
737 SmallPtrSet<void*, 4> &Set = ReversePtrDepIt->second;
738 SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
740 for (SmallPtrSet<void*, 4>::iterator I = Set.begin(), E = Set.end();
743 P.setFromOpaqueValue(*I);
744 assert(P.getPointer() != RemInst &&
745 "Already removed NonLocalPointerDeps info for RemInst");
747 NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P];
749 MemDepResult NewDirtyVal;
750 if (!RemInst->isTerminator())
751 NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
753 // Update any entries for RemInst to use the instruction after it.
754 for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
756 if (DI->second.getInst() != RemInst) continue;
758 // Convert to a dirty entry for the subsequent instruction.
759 DI->second = NewDirtyVal;
761 if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
762 ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
766 ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
768 while (!ReversePtrDepsToAdd.empty()) {
769 ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
770 .insert(ReversePtrDepsToAdd.back().second.getOpaqueValue());
771 ReversePtrDepsToAdd.pop_back();
776 assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
777 AA->deleteValue(RemInst);
778 DEBUG(verifyRemoved(RemInst));
781 /// verifyRemoved - Verify that the specified instruction does not occur
782 /// in our internal data structures.
783 void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
784 for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
785 E = LocalDeps.end(); I != E; ++I) {
786 assert(I->first != D && "Inst occurs in data structures");
787 assert(I->second.getInst() != D &&
788 "Inst occurs in data structures");
791 for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
792 E = NonLocalPointerDeps.end(); I != E; ++I) {
793 assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
794 const NonLocalDepInfo &Val = I->second;
795 for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
797 assert(II->second.getInst() != D && "Inst occurs as NLPD value");
800 for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
801 E = NonLocalDeps.end(); I != E; ++I) {
802 assert(I->first != D && "Inst occurs in data structures");
803 const PerInstNLInfo &INLD = I->second;
804 for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
805 EE = INLD.first.end(); II != EE; ++II)
806 assert(II->second.getInst() != D && "Inst occurs in data structures");
809 for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
810 E = ReverseLocalDeps.end(); I != E; ++I) {
811 assert(I->first != D && "Inst occurs in data structures");
812 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
813 EE = I->second.end(); II != EE; ++II)
814 assert(*II != D && "Inst occurs in data structures");
817 for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
818 E = ReverseNonLocalDeps.end();
820 assert(I->first != D && "Inst occurs in data structures");
821 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
822 EE = I->second.end(); II != EE; ++II)
823 assert(*II != D && "Inst occurs in data structures");
826 for (ReverseNonLocalPtrDepTy::const_iterator
827 I = ReverseNonLocalPtrDeps.begin(),
828 E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
829 assert(I->first != D && "Inst occurs in rev NLPD map");
831 for (SmallPtrSet<void*, 4>::const_iterator II = I->second.begin(),
832 E = I->second.end(); II != E; ++II)
833 assert(*II != ValueIsLoadPair(D, false).getOpaqueValue() &&
834 *II != ValueIsLoadPair(D, true).getOpaqueValue() &&
835 "Inst occurs in ReverseNonLocalPtrDeps map");