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/Instructions.h"
20 #include "llvm/IntrinsicInst.h"
21 #include "llvm/Function.h"
22 #include "llvm/LLVMContext.h"
23 #include "llvm/Analysis/AliasAnalysis.h"
24 #include "llvm/Analysis/Dominators.h"
25 #include "llvm/Analysis/InstructionSimplify.h"
26 #include "llvm/Analysis/MemoryBuiltins.h"
27 #include "llvm/Analysis/PHITransAddr.h"
28 #include "llvm/ADT/Statistic.h"
29 #include "llvm/ADT/STLExtras.h"
30 #include "llvm/Support/PredIteratorCache.h"
31 #include "llvm/Support/Debug.h"
34 STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
35 STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
36 STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
38 STATISTIC(NumCacheNonLocalPtr,
39 "Number of fully cached non-local ptr responses");
40 STATISTIC(NumCacheDirtyNonLocalPtr,
41 "Number of cached, but dirty, non-local ptr responses");
42 STATISTIC(NumUncacheNonLocalPtr,
43 "Number of uncached non-local ptr responses");
44 STATISTIC(NumCacheCompleteNonLocalPtr,
45 "Number of block queries that were completely cached");
47 char MemoryDependenceAnalysis::ID = 0;
49 // Register this pass...
50 INITIALIZE_PASS_BEGIN(MemoryDependenceAnalysis, "memdep",
51 "Memory Dependence Analysis", false, true)
52 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
53 INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep",
54 "Memory Dependence Analysis", false, true)
56 MemoryDependenceAnalysis::MemoryDependenceAnalysis()
57 : FunctionPass(ID), PredCache(0) {
58 initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry());
60 MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
63 /// Clean up memory in between runs
64 void MemoryDependenceAnalysis::releaseMemory() {
67 NonLocalPointerDeps.clear();
68 ReverseLocalDeps.clear();
69 ReverseNonLocalDeps.clear();
70 ReverseNonLocalPtrDeps.clear();
76 /// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
78 void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
80 AU.addRequiredTransitive<AliasAnalysis>();
83 bool MemoryDependenceAnalysis::runOnFunction(Function &) {
84 AA = &getAnalysis<AliasAnalysis>();
86 PredCache.reset(new PredIteratorCache());
90 /// RemoveFromReverseMap - This is a helper function that removes Val from
91 /// 'Inst's set in ReverseMap. If the set becomes empty, remove Inst's entry.
92 template <typename KeyTy>
93 static void RemoveFromReverseMap(DenseMap<Instruction*,
94 SmallPtrSet<KeyTy, 4> > &ReverseMap,
95 Instruction *Inst, KeyTy Val) {
96 typename DenseMap<Instruction*, SmallPtrSet<KeyTy, 4> >::iterator
97 InstIt = ReverseMap.find(Inst);
98 assert(InstIt != ReverseMap.end() && "Reverse map out of sync?");
99 bool Found = InstIt->second.erase(Val);
100 assert(Found && "Invalid reverse map!"); Found=Found;
101 if (InstIt->second.empty())
102 ReverseMap.erase(InstIt);
105 /// GetLocation - If the given instruction references a specific memory
106 /// location, fill in Loc with the details, otherwise set Loc.Ptr to null.
107 /// Return a ModRefInfo value describing the general behavior of the
110 AliasAnalysis::ModRefResult GetLocation(const Instruction *Inst,
111 AliasAnalysis::Location &Loc,
113 if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
114 if (LI->isVolatile()) {
115 Loc = AliasAnalysis::Location();
116 return AliasAnalysis::ModRef;
118 Loc = AA->getLocation(LI);
119 return AliasAnalysis::Ref;
122 if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
123 if (SI->isVolatile()) {
124 Loc = AliasAnalysis::Location();
125 return AliasAnalysis::ModRef;
127 Loc = AA->getLocation(SI);
128 return AliasAnalysis::Mod;
131 if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
132 Loc = AA->getLocation(V);
133 return AliasAnalysis::ModRef;
136 if (const CallInst *CI = isFreeCall(Inst)) {
137 // calls to free() deallocate the entire structure
138 Loc = AliasAnalysis::Location(CI->getArgOperand(0));
139 return AliasAnalysis::Mod;
142 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
143 switch (II->getIntrinsicID()) {
144 case Intrinsic::lifetime_start:
145 case Intrinsic::lifetime_end:
146 case Intrinsic::invariant_start:
147 Loc = AliasAnalysis::Location(II->getArgOperand(1),
148 cast<ConstantInt>(II->getArgOperand(0))
150 II->getMetadata(LLVMContext::MD_tbaa));
151 // These intrinsics don't really modify the memory, but returning Mod
152 // will allow them to be handled conservatively.
153 return AliasAnalysis::Mod;
154 case Intrinsic::invariant_end:
155 Loc = AliasAnalysis::Location(II->getArgOperand(2),
156 cast<ConstantInt>(II->getArgOperand(1))
158 II->getMetadata(LLVMContext::MD_tbaa));
159 // These intrinsics don't really modify the memory, but returning Mod
160 // will allow them to be handled conservatively.
161 return AliasAnalysis::Mod;
166 // Otherwise, just do the coarse-grained thing that always works.
167 if (Inst->mayWriteToMemory())
168 return AliasAnalysis::ModRef;
169 if (Inst->mayReadFromMemory())
170 return AliasAnalysis::Ref;
171 return AliasAnalysis::NoModRef;
174 /// getCallSiteDependencyFrom - Private helper for finding the local
175 /// dependencies of a call site.
176 MemDepResult MemoryDependenceAnalysis::
177 getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall,
178 BasicBlock::iterator ScanIt, BasicBlock *BB) {
179 // Walk backwards through the block, looking for dependencies
180 while (ScanIt != BB->begin()) {
181 Instruction *Inst = --ScanIt;
183 // If this inst is a memory op, get the pointer it accessed
184 AliasAnalysis::Location Loc;
185 AliasAnalysis::ModRefResult MR = GetLocation(Inst, Loc, AA);
187 // A simple instruction.
188 if (AA->getModRefInfo(CS, Loc) != AliasAnalysis::NoModRef)
189 return MemDepResult::getClobber(Inst);
193 if (CallSite InstCS = cast<Value>(Inst)) {
194 // Debug intrinsics don't cause dependences.
195 if (isa<DbgInfoIntrinsic>(Inst)) continue;
196 // If these two calls do not interfere, look past it.
197 switch (AA->getModRefInfo(CS, InstCS)) {
198 case AliasAnalysis::NoModRef:
199 // If the two calls are the same, return InstCS as a Def, so that
200 // CS can be found redundant and eliminated.
201 if (isReadOnlyCall && !(MR & AliasAnalysis::Mod) &&
202 CS.getInstruction()->isIdenticalToWhenDefined(Inst))
203 return MemDepResult::getDef(Inst);
205 // Otherwise if the two calls don't interact (e.g. InstCS is readnone)
209 return MemDepResult::getClobber(Inst);
214 // No dependence found. If this is the entry block of the function, it is a
215 // clobber, otherwise it is non-local.
216 if (BB != &BB->getParent()->getEntryBlock())
217 return MemDepResult::getNonLocal();
218 return MemDepResult::getClobber(ScanIt);
221 /// getPointerDependencyFrom - Return the instruction on which a memory
222 /// location depends. If isLoad is true, this routine ignores may-aliases with
223 /// read-only operations. If isLoad is false, this routine ignores may-aliases
224 /// with reads from read-only locations.
225 MemDepResult MemoryDependenceAnalysis::
226 getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
227 BasicBlock::iterator ScanIt, BasicBlock *BB) {
229 Value *InvariantTag = 0;
231 // Walk backwards through the basic block, looking for dependencies.
232 while (ScanIt != BB->begin()) {
233 Instruction *Inst = --ScanIt;
235 // If we're in an invariant region, no dependencies can be found before
236 // we pass an invariant-begin marker.
237 if (InvariantTag == Inst) {
242 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
243 // Debug intrinsics don't (and can't) cause dependences.
244 if (isa<DbgInfoIntrinsic>(II)) continue;
246 // If we pass an invariant-end marker, then we've just entered an
247 // invariant region and can start ignoring dependencies.
248 if (II->getIntrinsicID() == Intrinsic::invariant_end) {
249 // FIXME: This only considers queries directly on the invariant-tagged
250 // pointer, not on query pointers that are indexed off of them. It'd
251 // be nice to handle that at some point.
252 AliasAnalysis::AliasResult R =
253 AA->alias(AliasAnalysis::Location(II->getArgOperand(2)), MemLoc);
254 if (R == AliasAnalysis::MustAlias)
255 InvariantTag = II->getArgOperand(0);
260 // If we reach a lifetime begin or end marker, then the query ends here
261 // because the value is undefined.
262 if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
263 // FIXME: This only considers queries directly on the invariant-tagged
264 // pointer, not on query pointers that are indexed off of them. It'd
265 // be nice to handle that at some point.
266 AliasAnalysis::AliasResult R =
267 AA->alias(AliasAnalysis::Location(II->getArgOperand(1)), MemLoc);
268 if (R == AliasAnalysis::MustAlias)
269 return MemDepResult::getDef(II);
274 // If we're querying on a load and we're in an invariant region, we're done
275 // at this point. Nothing a load depends on can live in an invariant region.
277 // FIXME: this will prevent us from returning load/load must-aliases, so GVN
278 // won't remove redundant loads.
279 if (isLoad && InvariantTag) continue;
281 // Values depend on loads if the pointers are must aliased. This means that
282 // a load depends on another must aliased load from the same value.
283 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
284 AliasAnalysis::Location LoadLoc = AA->getLocation(LI);
286 // If we found a pointer, check if it could be the same as our pointer.
287 AliasAnalysis::AliasResult R = AA->alias(LoadLoc, MemLoc);
288 if (R == AliasAnalysis::NoAlias)
291 // May-alias loads don't depend on each other without a dependence.
292 if (isLoad && R == AliasAnalysis::MayAlias)
295 // Stores don't alias loads from read-only memory.
296 if (!isLoad && AA->pointsToConstantMemory(LoadLoc))
299 // Stores depend on may and must aliased loads, loads depend on must-alias
301 return MemDepResult::getDef(Inst);
304 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
305 // There can't be stores to the value we care about inside an
307 if (InvariantTag) continue;
309 // If alias analysis can tell that this store is guaranteed to not modify
310 // the query pointer, ignore it. Use getModRefInfo to handle cases where
311 // the query pointer points to constant memory etc.
312 if (AA->getModRefInfo(SI, MemLoc) == AliasAnalysis::NoModRef)
315 // Ok, this store might clobber the query pointer. Check to see if it is
316 // a must alias: in this case, we want to return this as a def.
317 AliasAnalysis::Location StoreLoc = AA->getLocation(SI);
319 // If we found a pointer, check if it could be the same as our pointer.
320 AliasAnalysis::AliasResult R = AA->alias(StoreLoc, MemLoc);
322 if (R == AliasAnalysis::NoAlias)
324 if (R == AliasAnalysis::MayAlias)
325 return MemDepResult::getClobber(Inst);
326 return MemDepResult::getDef(Inst);
329 // If this is an allocation, and if we know that the accessed pointer is to
330 // the allocation, return Def. This means that there is no dependence and
331 // the access can be optimized based on that. For example, a load could
333 // Note: Only determine this to be a malloc if Inst is the malloc call, not
334 // a subsequent bitcast of the malloc call result. There can be stores to
335 // the malloced memory between the malloc call and its bitcast uses, and we
336 // need to continue scanning until the malloc call.
337 if (isa<AllocaInst>(Inst) ||
338 (isa<CallInst>(Inst) && extractMallocCall(Inst))) {
339 const Value *AccessPtr = MemLoc.Ptr->getUnderlyingObject();
341 if (AccessPtr == Inst ||
342 AA->alias(Inst, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
343 return MemDepResult::getDef(Inst);
347 // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
348 switch (AA->getModRefInfo(Inst, MemLoc)) {
349 case AliasAnalysis::NoModRef:
350 // If the call has no effect on the queried pointer, just ignore it.
352 case AliasAnalysis::Mod:
353 // If we're in an invariant region, we can ignore calls that ONLY
354 // modify the pointer.
355 if (InvariantTag) continue;
356 return MemDepResult::getClobber(Inst);
357 case AliasAnalysis::Ref:
358 // If the call is known to never store to the pointer, and if this is a
359 // load query, we can safely ignore it (scan past it).
363 // Otherwise, there is a potential dependence. Return a clobber.
364 return MemDepResult::getClobber(Inst);
368 // No dependence found. If this is the entry block of the function, it is a
369 // clobber, otherwise it is non-local.
370 if (BB != &BB->getParent()->getEntryBlock())
371 return MemDepResult::getNonLocal();
372 return MemDepResult::getClobber(ScanIt);
375 /// getDependency - Return the instruction on which a memory operation
377 MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
378 Instruction *ScanPos = QueryInst;
380 // Check for a cached result
381 MemDepResult &LocalCache = LocalDeps[QueryInst];
383 // If the cached entry is non-dirty, just return it. Note that this depends
384 // on MemDepResult's default constructing to 'dirty'.
385 if (!LocalCache.isDirty())
388 // Otherwise, if we have a dirty entry, we know we can start the scan at that
389 // instruction, which may save us some work.
390 if (Instruction *Inst = LocalCache.getInst()) {
393 RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
396 BasicBlock *QueryParent = QueryInst->getParent();
399 if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
400 // No dependence found. If this is the entry block of the function, it is a
401 // clobber, otherwise it is non-local.
402 if (QueryParent != &QueryParent->getParent()->getEntryBlock())
403 LocalCache = MemDepResult::getNonLocal();
405 LocalCache = MemDepResult::getClobber(QueryInst);
407 AliasAnalysis::Location MemLoc;
408 AliasAnalysis::ModRefResult MR = GetLocation(QueryInst, MemLoc, AA);
410 // If we can do a pointer scan, make it happen.
411 bool isLoad = !(MR & AliasAnalysis::Mod);
412 if (IntrinsicInst *II = dyn_cast<MemoryUseIntrinsic>(QueryInst))
413 isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_end;
415 LocalCache = getPointerDependencyFrom(MemLoc, isLoad, ScanPos,
417 } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
418 CallSite QueryCS(QueryInst);
419 bool isReadOnly = AA->onlyReadsMemory(QueryCS);
420 LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
423 // Non-memory instruction.
424 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
427 // Remember the result!
428 if (Instruction *I = LocalCache.getInst())
429 ReverseLocalDeps[I].insert(QueryInst);
435 /// AssertSorted - This method is used when -debug is specified to verify that
436 /// cache arrays are properly kept sorted.
437 static void AssertSorted(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
439 if (Count == -1) Count = Cache.size();
440 if (Count == 0) return;
442 for (unsigned i = 1; i != unsigned(Count); ++i)
443 assert(!(Cache[i] < Cache[i-1]) && "Cache isn't sorted!");
447 /// getNonLocalCallDependency - Perform a full dependency query for the
448 /// specified call, returning the set of blocks that the value is
449 /// potentially live across. The returned set of results will include a
450 /// "NonLocal" result for all blocks where the value is live across.
452 /// This method assumes the instruction returns a "NonLocal" dependency
453 /// within its own block.
455 /// This returns a reference to an internal data structure that may be
456 /// invalidated on the next non-local query or when an instruction is
457 /// removed. Clients must copy this data if they want it around longer than
459 const MemoryDependenceAnalysis::NonLocalDepInfo &
460 MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
461 assert(getDependency(QueryCS.getInstruction()).isNonLocal() &&
462 "getNonLocalCallDependency should only be used on calls with non-local deps!");
463 PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()];
464 NonLocalDepInfo &Cache = CacheP.first;
466 /// DirtyBlocks - This is the set of blocks that need to be recomputed. In
467 /// the cached case, this can happen due to instructions being deleted etc. In
468 /// the uncached case, this starts out as the set of predecessors we care
470 SmallVector<BasicBlock*, 32> DirtyBlocks;
472 if (!Cache.empty()) {
473 // Okay, we have a cache entry. If we know it is not dirty, just return it
474 // with no computation.
475 if (!CacheP.second) {
480 // If we already have a partially computed set of results, scan them to
481 // determine what is dirty, seeding our initial DirtyBlocks worklist.
482 for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
484 if (I->getResult().isDirty())
485 DirtyBlocks.push_back(I->getBB());
487 // Sort the cache so that we can do fast binary search lookups below.
488 std::sort(Cache.begin(), Cache.end());
490 ++NumCacheDirtyNonLocal;
491 //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
492 // << Cache.size() << " cached: " << *QueryInst;
494 // Seed DirtyBlocks with each of the preds of QueryInst's block.
495 BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
496 for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
497 DirtyBlocks.push_back(*PI);
498 ++NumUncacheNonLocal;
501 // isReadonlyCall - If this is a read-only call, we can be more aggressive.
502 bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
504 SmallPtrSet<BasicBlock*, 64> Visited;
506 unsigned NumSortedEntries = Cache.size();
507 DEBUG(AssertSorted(Cache));
509 // Iterate while we still have blocks to update.
510 while (!DirtyBlocks.empty()) {
511 BasicBlock *DirtyBB = DirtyBlocks.back();
512 DirtyBlocks.pop_back();
514 // Already processed this block?
515 if (!Visited.insert(DirtyBB))
518 // Do a binary search to see if we already have an entry for this block in
519 // the cache set. If so, find it.
520 DEBUG(AssertSorted(Cache, NumSortedEntries));
521 NonLocalDepInfo::iterator Entry =
522 std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
523 NonLocalDepEntry(DirtyBB));
524 if (Entry != Cache.begin() && prior(Entry)->getBB() == DirtyBB)
527 NonLocalDepEntry *ExistingResult = 0;
528 if (Entry != Cache.begin()+NumSortedEntries &&
529 Entry->getBB() == DirtyBB) {
530 // If we already have an entry, and if it isn't already dirty, the block
532 if (!Entry->getResult().isDirty())
535 // Otherwise, remember this slot so we can update the value.
536 ExistingResult = &*Entry;
539 // If the dirty entry has a pointer, start scanning from it so we don't have
540 // to rescan the entire block.
541 BasicBlock::iterator ScanPos = DirtyBB->end();
542 if (ExistingResult) {
543 if (Instruction *Inst = ExistingResult->getResult().getInst()) {
545 // We're removing QueryInst's use of Inst.
546 RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
547 QueryCS.getInstruction());
551 // Find out if this block has a local dependency for QueryInst.
554 if (ScanPos != DirtyBB->begin()) {
555 Dep = getCallSiteDependencyFrom(QueryCS, isReadonlyCall,ScanPos, DirtyBB);
556 } else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) {
557 // No dependence found. If this is the entry block of the function, it is
558 // a clobber, otherwise it is non-local.
559 Dep = MemDepResult::getNonLocal();
561 Dep = MemDepResult::getClobber(ScanPos);
564 // If we had a dirty entry for the block, update it. Otherwise, just add
567 ExistingResult->setResult(Dep);
569 Cache.push_back(NonLocalDepEntry(DirtyBB, Dep));
571 // If the block has a dependency (i.e. it isn't completely transparent to
572 // the value), remember the association!
573 if (!Dep.isNonLocal()) {
574 // Keep the ReverseNonLocalDeps map up to date so we can efficiently
575 // update this when we remove instructions.
576 if (Instruction *Inst = Dep.getInst())
577 ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction());
580 // If the block *is* completely transparent to the load, we need to check
581 // the predecessors of this block. Add them to our worklist.
582 for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
583 DirtyBlocks.push_back(*PI);
590 /// getNonLocalPointerDependency - Perform a full dependency query for an
591 /// access to the specified (non-volatile) memory location, returning the
592 /// set of instructions that either define or clobber the value.
594 /// This method assumes the pointer has a "NonLocal" dependency within its
597 void MemoryDependenceAnalysis::
598 getNonLocalPointerDependency(const AliasAnalysis::Location &Loc, bool isLoad,
600 SmallVectorImpl<NonLocalDepResult> &Result) {
601 assert(Loc.Ptr->getType()->isPointerTy() &&
602 "Can't get pointer deps of a non-pointer!");
605 PHITransAddr Address(const_cast<Value *>(Loc.Ptr), TD);
607 // This is the set of blocks we've inspected, and the pointer we consider in
608 // each block. Because of critical edges, we currently bail out if querying
609 // a block with multiple different pointers. This can happen during PHI
611 DenseMap<BasicBlock*, Value*> Visited;
612 if (!getNonLocalPointerDepFromBB(Address, Loc, isLoad, FromBB,
613 Result, Visited, true))
616 Result.push_back(NonLocalDepResult(FromBB,
617 MemDepResult::getClobber(FromBB->begin()),
618 const_cast<Value *>(Loc.Ptr)));
621 /// GetNonLocalInfoForBlock - Compute the memdep value for BB with
622 /// Pointer/PointeeSize using either cached information in Cache or by doing a
623 /// lookup (which may use dirty cache info if available). If we do a lookup,
624 /// add the result to the cache.
625 MemDepResult MemoryDependenceAnalysis::
626 GetNonLocalInfoForBlock(const AliasAnalysis::Location &Loc,
627 bool isLoad, BasicBlock *BB,
628 NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
630 // Do a binary search to see if we already have an entry for this block in
631 // the cache set. If so, find it.
632 NonLocalDepInfo::iterator Entry =
633 std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
634 NonLocalDepEntry(BB));
635 if (Entry != Cache->begin() && (Entry-1)->getBB() == BB)
638 NonLocalDepEntry *ExistingResult = 0;
639 if (Entry != Cache->begin()+NumSortedEntries && Entry->getBB() == BB)
640 ExistingResult = &*Entry;
642 // If we have a cached entry, and it is non-dirty, use it as the value for
644 if (ExistingResult && !ExistingResult->getResult().isDirty()) {
645 ++NumCacheNonLocalPtr;
646 return ExistingResult->getResult();
649 // Otherwise, we have to scan for the value. If we have a dirty cache
650 // entry, start scanning from its position, otherwise we scan from the end
652 BasicBlock::iterator ScanPos = BB->end();
653 if (ExistingResult && ExistingResult->getResult().getInst()) {
654 assert(ExistingResult->getResult().getInst()->getParent() == BB &&
655 "Instruction invalidated?");
656 ++NumCacheDirtyNonLocalPtr;
657 ScanPos = ExistingResult->getResult().getInst();
659 // Eliminating the dirty entry from 'Cache', so update the reverse info.
660 ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
661 RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, CacheKey);
663 ++NumUncacheNonLocalPtr;
666 // Scan the block for the dependency.
667 MemDepResult Dep = getPointerDependencyFrom(Loc, isLoad, ScanPos, BB);
669 // If we had a dirty entry for the block, update it. Otherwise, just add
672 ExistingResult->setResult(Dep);
674 Cache->push_back(NonLocalDepEntry(BB, Dep));
676 // If the block has a dependency (i.e. it isn't completely transparent to
677 // the value), remember the reverse association because we just added it
679 if (Dep.isNonLocal())
682 // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
683 // update MemDep when we remove instructions.
684 Instruction *Inst = Dep.getInst();
685 assert(Inst && "Didn't depend on anything?");
686 ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
687 ReverseNonLocalPtrDeps[Inst].insert(CacheKey);
691 /// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain
692 /// number of elements in the array that are already properly ordered. This is
693 /// optimized for the case when only a few entries are added.
695 SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
696 unsigned NumSortedEntries) {
697 switch (Cache.size() - NumSortedEntries) {
699 // done, no new entries.
702 // Two new entries, insert the last one into place.
703 NonLocalDepEntry Val = Cache.back();
705 MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
706 std::upper_bound(Cache.begin(), Cache.end()-1, Val);
707 Cache.insert(Entry, Val);
711 // One new entry, Just insert the new value at the appropriate position.
712 if (Cache.size() != 1) {
713 NonLocalDepEntry Val = Cache.back();
715 MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
716 std::upper_bound(Cache.begin(), Cache.end(), Val);
717 Cache.insert(Entry, Val);
721 // Added many values, do a full scale sort.
722 std::sort(Cache.begin(), Cache.end());
727 /// getNonLocalPointerDepFromBB - Perform a dependency query based on
728 /// pointer/pointeesize starting at the end of StartBB. Add any clobber/def
729 /// results to the results vector and keep track of which blocks are visited in
732 /// This has special behavior for the first block queries (when SkipFirstBlock
733 /// is true). In this special case, it ignores the contents of the specified
734 /// block and starts returning dependence info for its predecessors.
736 /// This function returns false on success, or true to indicate that it could
737 /// not compute dependence information for some reason. This should be treated
738 /// as a clobber dependence on the first instruction in the predecessor block.
739 bool MemoryDependenceAnalysis::
740 getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
741 const AliasAnalysis::Location &Loc,
742 bool isLoad, BasicBlock *StartBB,
743 SmallVectorImpl<NonLocalDepResult> &Result,
744 DenseMap<BasicBlock*, Value*> &Visited,
745 bool SkipFirstBlock) {
747 // Look up the cached info for Pointer.
748 ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
750 // Set up a temporary NLPI value. If the map doesn't yet have an entry for
751 // CacheKey, this value will be inserted as the associated value. Otherwise,
752 // it'll be ignored, and we'll have to check to see if the cached size and
753 // tbaa tag are consistent with the current query.
754 NonLocalPointerInfo InitialNLPI;
755 InitialNLPI.Size = Loc.Size;
756 InitialNLPI.TBAATag = Loc.TBAATag;
758 // Get the NLPI for CacheKey, inserting one into the map if it doesn't
760 std::pair<CachedNonLocalPointerInfo::iterator, bool> Pair =
761 NonLocalPointerDeps.insert(std::make_pair(CacheKey, InitialNLPI));
762 NonLocalPointerInfo *CacheInfo = &Pair.first->second;
764 // If we already have a cache entry for this CacheKey, we may need to do some
765 // work to reconcile the cache entry and the current query.
767 if (CacheInfo->Size < Loc.Size) {
768 // The query's Size is greater than the cached one. Throw out the
769 // cached data and procede with the query at the greater size.
770 CacheInfo->Pair = BBSkipFirstBlockPair();
771 CacheInfo->Size = Loc.Size;
772 for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
773 DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
774 if (Instruction *Inst = DI->getResult().getInst())
775 RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
776 CacheInfo->NonLocalDeps.clear();
777 } else if (CacheInfo->Size > Loc.Size) {
778 // This query's Size is less than the cached one. Conservatively restart
779 // the query using the greater size.
780 return getNonLocalPointerDepFromBB(Pointer,
781 Loc.getWithNewSize(CacheInfo->Size),
782 isLoad, StartBB, Result, Visited,
786 // If the query's TBAATag is inconsistent with the cached one,
787 // conservatively throw out the cached data and restart the query with
789 if (CacheInfo->TBAATag != Loc.TBAATag) {
790 if (CacheInfo->TBAATag) {
791 CacheInfo->Pair = BBSkipFirstBlockPair();
792 CacheInfo->TBAATag = 0;
793 for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
794 DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
795 if (Instruction *Inst = DI->getResult().getInst())
796 RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
797 CacheInfo->NonLocalDeps.clear();
800 return getNonLocalPointerDepFromBB(Pointer, Loc.getWithoutTBAATag(),
801 isLoad, StartBB, Result, Visited,
806 NonLocalDepInfo *Cache = &CacheInfo->NonLocalDeps;
808 // If we have valid cached information for exactly the block we are
809 // investigating, just return it with no recomputation.
810 if (CacheInfo->Pair == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
811 // We have a fully cached result for this query then we can just return the
812 // cached results and populate the visited set. However, we have to verify
813 // that we don't already have conflicting results for these blocks. Check
814 // to ensure that if a block in the results set is in the visited set that
815 // it was for the same pointer query.
816 if (!Visited.empty()) {
817 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
819 DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->getBB());
820 if (VI == Visited.end() || VI->second == Pointer.getAddr())
823 // We have a pointer mismatch in a block. Just return clobber, saying
824 // that something was clobbered in this result. We could also do a
825 // non-fully cached query, but there is little point in doing this.
830 Value *Addr = Pointer.getAddr();
831 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
833 Visited.insert(std::make_pair(I->getBB(), Addr));
834 if (!I->getResult().isNonLocal())
835 Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr));
837 ++NumCacheCompleteNonLocalPtr;
841 // Otherwise, either this is a new block, a block with an invalid cache
842 // pointer or one that we're about to invalidate by putting more info into it
843 // than its valid cache info. If empty, the result will be valid cache info,
844 // otherwise it isn't.
846 CacheInfo->Pair = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
848 CacheInfo->Pair = BBSkipFirstBlockPair();
850 SmallVector<BasicBlock*, 32> Worklist;
851 Worklist.push_back(StartBB);
853 // Keep track of the entries that we know are sorted. Previously cached
854 // entries will all be sorted. The entries we add we only sort on demand (we
855 // don't insert every element into its sorted position). We know that we
856 // won't get any reuse from currently inserted values, because we don't
857 // revisit blocks after we insert info for them.
858 unsigned NumSortedEntries = Cache->size();
859 DEBUG(AssertSorted(*Cache));
861 while (!Worklist.empty()) {
862 BasicBlock *BB = Worklist.pop_back_val();
864 // Skip the first block if we have it.
865 if (!SkipFirstBlock) {
866 // Analyze the dependency of *Pointer in FromBB. See if we already have
868 assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
870 // Get the dependency info for Pointer in BB. If we have cached
871 // information, we will use it, otherwise we compute it.
872 DEBUG(AssertSorted(*Cache, NumSortedEntries));
873 MemDepResult Dep = GetNonLocalInfoForBlock(Loc, isLoad, BB, Cache,
876 // If we got a Def or Clobber, add this to the list of results.
877 if (!Dep.isNonLocal()) {
878 Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
883 // If 'Pointer' is an instruction defined in this block, then we need to do
884 // phi translation to change it into a value live in the predecessor block.
885 // If not, we just add the predecessors to the worklist and scan them with
887 if (!Pointer.NeedsPHITranslationFromBlock(BB)) {
888 SkipFirstBlock = false;
889 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
890 // Verify that we haven't looked at this block yet.
891 std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
892 InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr()));
893 if (InsertRes.second) {
894 // First time we've looked at *PI.
895 Worklist.push_back(*PI);
899 // If we have seen this block before, but it was with a different
900 // pointer then we have a phi translation failure and we have to treat
901 // this as a clobber.
902 if (InsertRes.first->second != Pointer.getAddr())
903 goto PredTranslationFailure;
908 // We do need to do phi translation, if we know ahead of time we can't phi
909 // translate this value, don't even try.
910 if (!Pointer.IsPotentiallyPHITranslatable())
911 goto PredTranslationFailure;
913 // We may have added values to the cache list before this PHI translation.
914 // If so, we haven't done anything to ensure that the cache remains sorted.
915 // Sort it now (if needed) so that recursive invocations of
916 // getNonLocalPointerDepFromBB and other routines that could reuse the cache
917 // value will only see properly sorted cache arrays.
918 if (Cache && NumSortedEntries != Cache->size()) {
919 SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
920 NumSortedEntries = Cache->size();
924 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
925 BasicBlock *Pred = *PI;
927 // Get the PHI translated pointer in this predecessor. This can fail if
928 // not translatable, in which case the getAddr() returns null.
929 PHITransAddr PredPointer(Pointer);
930 PredPointer.PHITranslateValue(BB, Pred, 0);
932 Value *PredPtrVal = PredPointer.getAddr();
934 // Check to see if we have already visited this pred block with another
935 // pointer. If so, we can't do this lookup. This failure can occur
936 // with PHI translation when a critical edge exists and the PHI node in
937 // the successor translates to a pointer value different than the
938 // pointer the block was first analyzed with.
939 std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
940 InsertRes = Visited.insert(std::make_pair(Pred, PredPtrVal));
942 if (!InsertRes.second) {
943 // If the predecessor was visited with PredPtr, then we already did
944 // the analysis and can ignore it.
945 if (InsertRes.first->second == PredPtrVal)
948 // Otherwise, the block was previously analyzed with a different
949 // pointer. We can't represent the result of this case, so we just
950 // treat this as a phi translation failure.
951 goto PredTranslationFailure;
954 // If PHI translation was unable to find an available pointer in this
955 // predecessor, then we have to assume that the pointer is clobbered in
956 // that predecessor. We can still do PRE of the load, which would insert
957 // a computation of the pointer in this predecessor.
958 if (PredPtrVal == 0) {
959 // Add the entry to the Result list.
960 NonLocalDepResult Entry(Pred,
961 MemDepResult::getClobber(Pred->getTerminator()),
963 Result.push_back(Entry);
965 // Since we had a phi translation failure, the cache for CacheKey won't
966 // include all of the entries that we need to immediately satisfy future
967 // queries. Mark this in NonLocalPointerDeps by setting the
968 // BBSkipFirstBlockPair pointer to null. This requires reuse of the
969 // cached value to do more work but not miss the phi trans failure.
970 NonLocalPointerInfo &NLPI = NonLocalPointerDeps[CacheKey];
971 NLPI.Pair = BBSkipFirstBlockPair();
975 // FIXME: it is entirely possible that PHI translating will end up with
976 // the same value. Consider PHI translating something like:
977 // X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need*
978 // to recurse here, pedantically speaking.
980 // If we have a problem phi translating, fall through to the code below
981 // to handle the failure condition.
982 if (getNonLocalPointerDepFromBB(PredPointer,
983 Loc.getWithNewPtr(PredPointer.getAddr()),
986 goto PredTranslationFailure;
989 // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
990 CacheInfo = &NonLocalPointerDeps[CacheKey];
991 Cache = &CacheInfo->NonLocalDeps;
992 NumSortedEntries = Cache->size();
994 // Since we did phi translation, the "Cache" set won't contain all of the
995 // results for the query. This is ok (we can still use it to accelerate
996 // specific block queries) but we can't do the fastpath "return all
997 // results from the set" Clear out the indicator for this.
998 CacheInfo->Pair = BBSkipFirstBlockPair();
999 SkipFirstBlock = false;
1002 PredTranslationFailure:
1005 // Refresh the CacheInfo/Cache pointer if it got invalidated.
1006 CacheInfo = &NonLocalPointerDeps[CacheKey];
1007 Cache = &CacheInfo->NonLocalDeps;
1008 NumSortedEntries = Cache->size();
1011 // Since we failed phi translation, the "Cache" set won't contain all of the
1012 // results for the query. This is ok (we can still use it to accelerate
1013 // specific block queries) but we can't do the fastpath "return all
1014 // results from the set". Clear out the indicator for this.
1015 CacheInfo->Pair = BBSkipFirstBlockPair();
1017 // If *nothing* works, mark the pointer as being clobbered by the first
1018 // instruction in this block.
1020 // If this is the magic first block, return this as a clobber of the whole
1021 // incoming value. Since we can't phi translate to one of the predecessors,
1022 // we have to bail out.
1026 for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) {
1027 assert(I != Cache->rend() && "Didn't find current block??");
1028 if (I->getBB() != BB)
1031 assert(I->getResult().isNonLocal() &&
1032 "Should only be here with transparent block");
1033 I->setResult(MemDepResult::getClobber(BB->begin()));
1034 ReverseNonLocalPtrDeps[BB->begin()].insert(CacheKey);
1035 Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(),
1036 Pointer.getAddr()));
1041 // Okay, we're done now. If we added new values to the cache, re-sort it.
1042 SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
1043 DEBUG(AssertSorted(*Cache));
1047 /// RemoveCachedNonLocalPointerDependencies - If P exists in
1048 /// CachedNonLocalPointerInfo, remove it.
1049 void MemoryDependenceAnalysis::
1050 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
1051 CachedNonLocalPointerInfo::iterator It =
1052 NonLocalPointerDeps.find(P);
1053 if (It == NonLocalPointerDeps.end()) return;
1055 // Remove all of the entries in the BB->val map. This involves removing
1056 // instructions from the reverse map.
1057 NonLocalDepInfo &PInfo = It->second.NonLocalDeps;
1059 for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
1060 Instruction *Target = PInfo[i].getResult().getInst();
1061 if (Target == 0) continue; // Ignore non-local dep results.
1062 assert(Target->getParent() == PInfo[i].getBB());
1064 // Eliminating the dirty entry from 'Cache', so update the reverse info.
1065 RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P);
1068 // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
1069 NonLocalPointerDeps.erase(It);
1073 /// invalidateCachedPointerInfo - This method is used to invalidate cached
1074 /// information about the specified pointer, because it may be too
1075 /// conservative in memdep. This is an optional call that can be used when
1076 /// the client detects an equivalence between the pointer and some other
1077 /// value and replaces the other value with ptr. This can make Ptr available
1078 /// in more places that cached info does not necessarily keep.
1079 void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
1080 // If Ptr isn't really a pointer, just ignore it.
1081 if (!Ptr->getType()->isPointerTy()) return;
1082 // Flush store info for the pointer.
1083 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
1084 // Flush load info for the pointer.
1085 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
1088 /// invalidateCachedPredecessors - Clear the PredIteratorCache info.
1089 /// This needs to be done when the CFG changes, e.g., due to splitting
1091 void MemoryDependenceAnalysis::invalidateCachedPredecessors() {
1095 /// removeInstruction - Remove an instruction from the dependence analysis,
1096 /// updating the dependence of instructions that previously depended on it.
1097 /// This method attempts to keep the cache coherent using the reverse map.
1098 void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
1099 // Walk through the Non-local dependencies, removing this one as the value
1100 // for any cached queries.
1101 NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
1102 if (NLDI != NonLocalDeps.end()) {
1103 NonLocalDepInfo &BlockMap = NLDI->second.first;
1104 for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
1106 if (Instruction *Inst = DI->getResult().getInst())
1107 RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
1108 NonLocalDeps.erase(NLDI);
1111 // If we have a cached local dependence query for this instruction, remove it.
1113 LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
1114 if (LocalDepEntry != LocalDeps.end()) {
1115 // Remove us from DepInst's reverse set now that the local dep info is gone.
1116 if (Instruction *Inst = LocalDepEntry->second.getInst())
1117 RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
1119 // Remove this local dependency info.
1120 LocalDeps.erase(LocalDepEntry);
1123 // If we have any cached pointer dependencies on this instruction, remove
1124 // them. If the instruction has non-pointer type, then it can't be a pointer
1127 // Remove it from both the load info and the store info. The instruction
1128 // can't be in either of these maps if it is non-pointer.
1129 if (RemInst->getType()->isPointerTy()) {
1130 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
1131 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
1134 // Loop over all of the things that depend on the instruction we're removing.
1136 SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
1138 // If we find RemInst as a clobber or Def in any of the maps for other values,
1139 // we need to replace its entry with a dirty version of the instruction after
1140 // it. If RemInst is a terminator, we use a null dirty value.
1142 // Using a dirty version of the instruction after RemInst saves having to scan
1143 // the entire block to get to this point.
1144 MemDepResult NewDirtyVal;
1145 if (!RemInst->isTerminator())
1146 NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
1148 ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
1149 if (ReverseDepIt != ReverseLocalDeps.end()) {
1150 SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
1151 // RemInst can't be the terminator if it has local stuff depending on it.
1152 assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
1153 "Nothing can locally depend on a terminator");
1155 for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
1156 E = ReverseDeps.end(); I != E; ++I) {
1157 Instruction *InstDependingOnRemInst = *I;
1158 assert(InstDependingOnRemInst != RemInst &&
1159 "Already removed our local dep info");
1161 LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
1163 // Make sure to remember that new things depend on NewDepInst.
1164 assert(NewDirtyVal.getInst() && "There is no way something else can have "
1165 "a local dep on this if it is a terminator!");
1166 ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(),
1167 InstDependingOnRemInst));
1170 ReverseLocalDeps.erase(ReverseDepIt);
1172 // Add new reverse deps after scanning the set, to avoid invalidating the
1173 // 'ReverseDeps' reference.
1174 while (!ReverseDepsToAdd.empty()) {
1175 ReverseLocalDeps[ReverseDepsToAdd.back().first]
1176 .insert(ReverseDepsToAdd.back().second);
1177 ReverseDepsToAdd.pop_back();
1181 ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
1182 if (ReverseDepIt != ReverseNonLocalDeps.end()) {
1183 SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
1184 for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
1186 assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
1188 PerInstNLInfo &INLD = NonLocalDeps[*I];
1189 // The information is now dirty!
1192 for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
1193 DE = INLD.first.end(); DI != DE; ++DI) {
1194 if (DI->getResult().getInst() != RemInst) continue;
1196 // Convert to a dirty entry for the subsequent instruction.
1197 DI->setResult(NewDirtyVal);
1199 if (Instruction *NextI = NewDirtyVal.getInst())
1200 ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
1204 ReverseNonLocalDeps.erase(ReverseDepIt);
1206 // Add new reverse deps after scanning the set, to avoid invalidating 'Set'
1207 while (!ReverseDepsToAdd.empty()) {
1208 ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
1209 .insert(ReverseDepsToAdd.back().second);
1210 ReverseDepsToAdd.pop_back();
1214 // If the instruction is in ReverseNonLocalPtrDeps then it appears as a
1215 // value in the NonLocalPointerDeps info.
1216 ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
1217 ReverseNonLocalPtrDeps.find(RemInst);
1218 if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
1219 SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second;
1220 SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
1222 for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(),
1223 E = Set.end(); I != E; ++I) {
1224 ValueIsLoadPair P = *I;
1225 assert(P.getPointer() != RemInst &&
1226 "Already removed NonLocalPointerDeps info for RemInst");
1228 NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].NonLocalDeps;
1230 // The cache is not valid for any specific block anymore.
1231 NonLocalPointerDeps[P].Pair = BBSkipFirstBlockPair();
1233 // Update any entries for RemInst to use the instruction after it.
1234 for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
1236 if (DI->getResult().getInst() != RemInst) continue;
1238 // Convert to a dirty entry for the subsequent instruction.
1239 DI->setResult(NewDirtyVal);
1241 if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
1242 ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
1245 // Re-sort the NonLocalDepInfo. Changing the dirty entry to its
1246 // subsequent value may invalidate the sortedness.
1247 std::sort(NLPDI.begin(), NLPDI.end());
1250 ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
1252 while (!ReversePtrDepsToAdd.empty()) {
1253 ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
1254 .insert(ReversePtrDepsToAdd.back().second);
1255 ReversePtrDepsToAdd.pop_back();
1260 assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
1261 AA->deleteValue(RemInst);
1262 DEBUG(verifyRemoved(RemInst));
1264 /// verifyRemoved - Verify that the specified instruction does not occur
1265 /// in our internal data structures.
1266 void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
1267 for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
1268 E = LocalDeps.end(); I != E; ++I) {
1269 assert(I->first != D && "Inst occurs in data structures");
1270 assert(I->second.getInst() != D &&
1271 "Inst occurs in data structures");
1274 for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
1275 E = NonLocalPointerDeps.end(); I != E; ++I) {
1276 assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
1277 const NonLocalDepInfo &Val = I->second.NonLocalDeps;
1278 for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
1280 assert(II->getResult().getInst() != D && "Inst occurs as NLPD value");
1283 for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
1284 E = NonLocalDeps.end(); I != E; ++I) {
1285 assert(I->first != D && "Inst occurs in data structures");
1286 const PerInstNLInfo &INLD = I->second;
1287 for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
1288 EE = INLD.first.end(); II != EE; ++II)
1289 assert(II->getResult().getInst() != D && "Inst occurs in data structures");
1292 for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
1293 E = ReverseLocalDeps.end(); I != E; ++I) {
1294 assert(I->first != D && "Inst occurs in data structures");
1295 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
1296 EE = I->second.end(); II != EE; ++II)
1297 assert(*II != D && "Inst occurs in data structures");
1300 for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
1301 E = ReverseNonLocalDeps.end();
1303 assert(I->first != D && "Inst occurs in data structures");
1304 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
1305 EE = I->second.end(); II != EE; ++II)
1306 assert(*II != D && "Inst occurs in data structures");
1309 for (ReverseNonLocalPtrDepTy::const_iterator
1310 I = ReverseNonLocalPtrDeps.begin(),
1311 E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
1312 assert(I->first != D && "Inst occurs in rev NLPD map");
1314 for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(),
1315 E = I->second.end(); II != E; ++II)
1316 assert(*II != ValueIsLoadPair(D, false) &&
1317 *II != ValueIsLoadPair(D, true) &&
1318 "Inst occurs in ReverseNonLocalPtrDeps map");