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/Analysis/AliasAnalysis.h"
23 #include "llvm/Analysis/Dominators.h"
24 #include "llvm/Analysis/InstructionSimplify.h"
25 #include "llvm/Analysis/MemoryBuiltins.h"
26 #include "llvm/ADT/Statistic.h"
27 #include "llvm/ADT/STLExtras.h"
28 #include "llvm/Support/PredIteratorCache.h"
29 #include "llvm/Support/Debug.h"
32 STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
33 STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
34 STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
36 STATISTIC(NumCacheNonLocalPtr,
37 "Number of fully cached non-local ptr responses");
38 STATISTIC(NumCacheDirtyNonLocalPtr,
39 "Number of cached, but dirty, non-local ptr responses");
40 STATISTIC(NumUncacheNonLocalPtr,
41 "Number of uncached non-local ptr responses");
42 STATISTIC(NumCacheCompleteNonLocalPtr,
43 "Number of block queries that were completely cached");
45 char MemoryDependenceAnalysis::ID = 0;
47 // Register this pass...
48 static RegisterPass<MemoryDependenceAnalysis> X("memdep",
49 "Memory Dependence Analysis", false, true);
51 MemoryDependenceAnalysis::MemoryDependenceAnalysis()
52 : FunctionPass(&ID), PredCache(0) {
54 MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
57 /// Clean up memory in between runs
58 void MemoryDependenceAnalysis::releaseMemory() {
61 NonLocalPointerDeps.clear();
62 ReverseLocalDeps.clear();
63 ReverseNonLocalDeps.clear();
64 ReverseNonLocalPtrDeps.clear();
70 /// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
72 void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
74 AU.addRequiredTransitive<AliasAnalysis>();
77 bool MemoryDependenceAnalysis::runOnFunction(Function &) {
78 AA = &getAnalysis<AliasAnalysis>();
80 PredCache.reset(new PredIteratorCache());
84 /// RemoveFromReverseMap - This is a helper function that removes Val from
85 /// 'Inst's set in ReverseMap. If the set becomes empty, remove Inst's entry.
86 template <typename KeyTy>
87 static void RemoveFromReverseMap(DenseMap<Instruction*,
88 SmallPtrSet<KeyTy, 4> > &ReverseMap,
89 Instruction *Inst, KeyTy Val) {
90 typename DenseMap<Instruction*, SmallPtrSet<KeyTy, 4> >::iterator
91 InstIt = ReverseMap.find(Inst);
92 assert(InstIt != ReverseMap.end() && "Reverse map out of sync?");
93 bool Found = InstIt->second.erase(Val);
94 assert(Found && "Invalid reverse map!"); Found=Found;
95 if (InstIt->second.empty())
96 ReverseMap.erase(InstIt);
100 /// getCallSiteDependencyFrom - Private helper for finding the local
101 /// dependencies of a call site.
102 MemDepResult MemoryDependenceAnalysis::
103 getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall,
104 BasicBlock::iterator ScanIt, BasicBlock *BB) {
105 // Walk backwards through the block, looking for dependencies
106 while (ScanIt != BB->begin()) {
107 Instruction *Inst = --ScanIt;
109 // If this inst is a memory op, get the pointer it accessed
111 uint64_t PointerSize = 0;
112 if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
113 Pointer = S->getPointerOperand();
114 PointerSize = AA->getTypeStoreSize(S->getOperand(0)->getType());
115 } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
116 Pointer = V->getOperand(0);
117 PointerSize = AA->getTypeStoreSize(V->getType());
118 } else if (isFreeCall(Inst)) {
119 Pointer = Inst->getOperand(1);
120 // calls to free() erase the entire structure
122 } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
123 // Debug intrinsics don't cause dependences.
124 if (isa<DbgInfoIntrinsic>(Inst)) continue;
125 CallSite InstCS = CallSite::get(Inst);
126 // If these two calls do not interfere, look past it.
127 switch (AA->getModRefInfo(CS, InstCS)) {
128 case AliasAnalysis::NoModRef:
129 // If the two calls don't interact (e.g. InstCS is readnone) keep
132 case AliasAnalysis::Ref:
133 // If the two calls read the same memory locations and CS is a readonly
134 // function, then we have two cases: 1) the calls may not interfere with
135 // each other at all. 2) the calls may produce the same value. In case
136 // #1 we want to ignore the values, in case #2, we want to return Inst
137 // as a Def dependence. This allows us to CSE in cases like:
140 // Y = strlen(P); // Y = X
141 if (isReadOnlyCall) {
142 if (CS.getCalledFunction() != 0 &&
143 CS.getCalledFunction() == InstCS.getCalledFunction())
144 return MemDepResult::getDef(Inst);
145 // Ignore unrelated read/read call dependences.
150 return MemDepResult::getClobber(Inst);
153 // Non-memory instruction.
157 if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
158 return MemDepResult::getClobber(Inst);
161 // No dependence found. If this is the entry block of the function, it is a
162 // clobber, otherwise it is non-local.
163 if (BB != &BB->getParent()->getEntryBlock())
164 return MemDepResult::getNonLocal();
165 return MemDepResult::getClobber(ScanIt);
168 /// getPointerDependencyFrom - Return the instruction on which a memory
169 /// location depends. If isLoad is true, this routine ignore may-aliases with
170 /// read-only operations.
171 MemDepResult MemoryDependenceAnalysis::
172 getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
173 BasicBlock::iterator ScanIt, BasicBlock *BB) {
175 Value *invariantTag = 0;
177 // Walk backwards through the basic block, looking for dependencies.
178 while (ScanIt != BB->begin()) {
179 Instruction *Inst = --ScanIt;
181 // If we're in an invariant region, no dependencies can be found before
182 // we pass an invariant-begin marker.
183 if (invariantTag == Inst) {
186 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
187 // If we pass an invariant-end marker, then we've just entered an
188 // invariant region and can start ignoring dependencies.
189 if (II->getIntrinsicID() == Intrinsic::invariant_end) {
190 uint64_t invariantSize = ~0ULL;
191 if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(2)))
192 invariantSize = CI->getZExtValue();
194 AliasAnalysis::AliasResult R =
195 AA->alias(II->getOperand(3), invariantSize, MemPtr, MemSize);
196 if (R == AliasAnalysis::MustAlias) {
197 invariantTag = II->getOperand(1);
201 // If we reach a lifetime begin or end marker, then the query ends here
202 // because the value is undefined.
203 } else if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
204 II->getIntrinsicID() == Intrinsic::lifetime_end) {
205 uint64_t invariantSize = ~0ULL;
206 if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(1)))
207 invariantSize = CI->getZExtValue();
209 AliasAnalysis::AliasResult R =
210 AA->alias(II->getOperand(2), invariantSize, MemPtr, MemSize);
211 if (R == AliasAnalysis::MustAlias)
212 return MemDepResult::getDef(II);
216 // If we're querying on a load and we're in an invariant region, we're done
217 // at this point. Nothing a load depends on can live in an invariant region.
218 if (isLoad && invariantTag) continue;
220 // Debug intrinsics don't cause dependences.
221 if (isa<DbgInfoIntrinsic>(Inst)) continue;
223 // Values depend on loads if the pointers are must aliased. This means that
224 // a load depends on another must aliased load from the same value.
225 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
226 Value *Pointer = LI->getPointerOperand();
227 uint64_t PointerSize = AA->getTypeStoreSize(LI->getType());
229 // If we found a pointer, check if it could be the same as our pointer.
230 AliasAnalysis::AliasResult R =
231 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
232 if (R == AliasAnalysis::NoAlias)
235 // May-alias loads don't depend on each other without a dependence.
236 if (isLoad && R == AliasAnalysis::MayAlias)
238 // Stores depend on may and must aliased loads, loads depend on must-alias
240 return MemDepResult::getDef(Inst);
243 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
244 // There can't be stores to the value we care about inside an
246 if (invariantTag) continue;
248 // If alias analysis can tell that this store is guaranteed to not modify
249 // the query pointer, ignore it. Use getModRefInfo to handle cases where
250 // the query pointer points to constant memory etc.
251 if (AA->getModRefInfo(SI, MemPtr, MemSize) == AliasAnalysis::NoModRef)
254 // Ok, this store might clobber the query pointer. Check to see if it is
255 // a must alias: in this case, we want to return this as a def.
256 Value *Pointer = SI->getPointerOperand();
257 uint64_t PointerSize = AA->getTypeStoreSize(SI->getOperand(0)->getType());
259 // If we found a pointer, check if it could be the same as our pointer.
260 AliasAnalysis::AliasResult R =
261 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
263 if (R == AliasAnalysis::NoAlias)
265 if (R == AliasAnalysis::MayAlias)
266 return MemDepResult::getClobber(Inst);
267 return MemDepResult::getDef(Inst);
270 // If this is an allocation, and if we know that the accessed pointer is to
271 // the allocation, return Def. This means that there is no dependence and
272 // the access can be optimized based on that. For example, a load could
274 // Note: Only determine this to be a malloc if Inst is the malloc call, not
275 // a subsequent bitcast of the malloc call result. There can be stores to
276 // the malloced memory between the malloc call and its bitcast uses, and we
277 // need to continue scanning until the malloc call.
278 if (isa<AllocaInst>(Inst) || extractMallocCall(Inst)) {
279 Value *AccessPtr = MemPtr->getUnderlyingObject();
281 if (AccessPtr == Inst ||
282 AA->alias(Inst, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
283 return MemDepResult::getDef(Inst);
287 // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
288 switch (AA->getModRefInfo(Inst, MemPtr, MemSize)) {
289 case AliasAnalysis::NoModRef:
290 // If the call has no effect on the queried pointer, just ignore it.
292 case AliasAnalysis::Mod:
293 // If we're in an invariant region, we can ignore calls that ONLY
294 // modify the pointer.
295 if (invariantTag) continue;
296 return MemDepResult::getClobber(Inst);
297 case AliasAnalysis::Ref:
298 // If the call is known to never store to the pointer, and if this is a
299 // load query, we can safely ignore it (scan past it).
303 // Otherwise, there is a potential dependence. Return a clobber.
304 return MemDepResult::getClobber(Inst);
308 // No dependence found. If this is the entry block of the function, it is a
309 // clobber, otherwise it is non-local.
310 if (BB != &BB->getParent()->getEntryBlock())
311 return MemDepResult::getNonLocal();
312 return MemDepResult::getClobber(ScanIt);
315 /// getDependency - Return the instruction on which a memory operation
317 MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
318 Instruction *ScanPos = QueryInst;
320 // Check for a cached result
321 MemDepResult &LocalCache = LocalDeps[QueryInst];
323 // If the cached entry is non-dirty, just return it. Note that this depends
324 // on MemDepResult's default constructing to 'dirty'.
325 if (!LocalCache.isDirty())
328 // Otherwise, if we have a dirty entry, we know we can start the scan at that
329 // instruction, which may save us some work.
330 if (Instruction *Inst = LocalCache.getInst()) {
333 RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
336 BasicBlock *QueryParent = QueryInst->getParent();
339 uint64_t MemSize = 0;
342 if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
343 // No dependence found. If this is the entry block of the function, it is a
344 // clobber, otherwise it is non-local.
345 if (QueryParent != &QueryParent->getParent()->getEntryBlock())
346 LocalCache = MemDepResult::getNonLocal();
348 LocalCache = MemDepResult::getClobber(QueryInst);
349 } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
350 // If this is a volatile store, don't mess around with it. Just return the
351 // previous instruction as a clobber.
352 if (SI->isVolatile())
353 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
355 MemPtr = SI->getPointerOperand();
356 MemSize = AA->getTypeStoreSize(SI->getOperand(0)->getType());
358 } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
359 // If this is a volatile load, don't mess around with it. Just return the
360 // previous instruction as a clobber.
361 if (LI->isVolatile())
362 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
364 MemPtr = LI->getPointerOperand();
365 MemSize = AA->getTypeStoreSize(LI->getType());
367 } else if (isFreeCall(QueryInst)) {
368 MemPtr = QueryInst->getOperand(1);
369 // calls to free() erase the entire structure, not just a field.
371 } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
372 CallSite QueryCS = CallSite::get(QueryInst);
373 bool isReadOnly = AA->onlyReadsMemory(QueryCS);
374 LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
377 // Non-memory instruction.
378 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
381 // If we need to do a pointer scan, make it happen.
383 LocalCache = getPointerDependencyFrom(MemPtr, MemSize,
384 isa<LoadInst>(QueryInst),
385 ScanPos, QueryParent);
387 // Remember the result!
388 if (Instruction *I = LocalCache.getInst())
389 ReverseLocalDeps[I].insert(QueryInst);
395 /// AssertSorted - This method is used when -debug is specified to verify that
396 /// cache arrays are properly kept sorted.
397 static void AssertSorted(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
399 if (Count == -1) Count = Cache.size();
400 if (Count == 0) return;
402 for (unsigned i = 1; i != unsigned(Count); ++i)
403 assert(Cache[i-1] <= Cache[i] && "Cache isn't sorted!");
407 /// getNonLocalCallDependency - Perform a full dependency query for the
408 /// specified call, returning the set of blocks that the value is
409 /// potentially live across. The returned set of results will include a
410 /// "NonLocal" result for all blocks where the value is live across.
412 /// This method assumes the instruction returns a "NonLocal" dependency
413 /// within its own block.
415 /// This returns a reference to an internal data structure that may be
416 /// invalidated on the next non-local query or when an instruction is
417 /// removed. Clients must copy this data if they want it around longer than
419 const MemoryDependenceAnalysis::NonLocalDepInfo &
420 MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
421 assert(getDependency(QueryCS.getInstruction()).isNonLocal() &&
422 "getNonLocalCallDependency should only be used on calls with non-local deps!");
423 PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()];
424 NonLocalDepInfo &Cache = CacheP.first;
426 /// DirtyBlocks - This is the set of blocks that need to be recomputed. In
427 /// the cached case, this can happen due to instructions being deleted etc. In
428 /// the uncached case, this starts out as the set of predecessors we care
430 SmallVector<BasicBlock*, 32> DirtyBlocks;
432 if (!Cache.empty()) {
433 // Okay, we have a cache entry. If we know it is not dirty, just return it
434 // with no computation.
435 if (!CacheP.second) {
440 // If we already have a partially computed set of results, scan them to
441 // determine what is dirty, seeding our initial DirtyBlocks worklist.
442 for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
444 if (I->second.isDirty())
445 DirtyBlocks.push_back(I->first);
447 // Sort the cache so that we can do fast binary search lookups below.
448 std::sort(Cache.begin(), Cache.end());
450 ++NumCacheDirtyNonLocal;
451 //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
452 // << Cache.size() << " cached: " << *QueryInst;
454 // Seed DirtyBlocks with each of the preds of QueryInst's block.
455 BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
456 for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
457 DirtyBlocks.push_back(*PI);
458 NumUncacheNonLocal++;
461 // isReadonlyCall - If this is a read-only call, we can be more aggressive.
462 bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
464 SmallPtrSet<BasicBlock*, 64> Visited;
466 unsigned NumSortedEntries = Cache.size();
467 DEBUG(AssertSorted(Cache));
469 // Iterate while we still have blocks to update.
470 while (!DirtyBlocks.empty()) {
471 BasicBlock *DirtyBB = DirtyBlocks.back();
472 DirtyBlocks.pop_back();
474 // Already processed this block?
475 if (!Visited.insert(DirtyBB))
478 // Do a binary search to see if we already have an entry for this block in
479 // the cache set. If so, find it.
480 DEBUG(AssertSorted(Cache, NumSortedEntries));
481 NonLocalDepInfo::iterator Entry =
482 std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
483 std::make_pair(DirtyBB, MemDepResult()));
484 if (Entry != Cache.begin() && prior(Entry)->first == DirtyBB)
487 MemDepResult *ExistingResult = 0;
488 if (Entry != Cache.begin()+NumSortedEntries &&
489 Entry->first == DirtyBB) {
490 // If we already have an entry, and if it isn't already dirty, the block
492 if (!Entry->second.isDirty())
495 // Otherwise, remember this slot so we can update the value.
496 ExistingResult = &Entry->second;
499 // If the dirty entry has a pointer, start scanning from it so we don't have
500 // to rescan the entire block.
501 BasicBlock::iterator ScanPos = DirtyBB->end();
502 if (ExistingResult) {
503 if (Instruction *Inst = ExistingResult->getInst()) {
505 // We're removing QueryInst's use of Inst.
506 RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
507 QueryCS.getInstruction());
511 // Find out if this block has a local dependency for QueryInst.
514 if (ScanPos != DirtyBB->begin()) {
515 Dep = getCallSiteDependencyFrom(QueryCS, isReadonlyCall,ScanPos, DirtyBB);
516 } else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) {
517 // No dependence found. If this is the entry block of the function, it is
518 // a clobber, otherwise it is non-local.
519 Dep = MemDepResult::getNonLocal();
521 Dep = MemDepResult::getClobber(ScanPos);
524 // If we had a dirty entry for the block, update it. Otherwise, just add
527 *ExistingResult = Dep;
529 Cache.push_back(std::make_pair(DirtyBB, Dep));
531 // If the block has a dependency (i.e. it isn't completely transparent to
532 // the value), remember the association!
533 if (!Dep.isNonLocal()) {
534 // Keep the ReverseNonLocalDeps map up to date so we can efficiently
535 // update this when we remove instructions.
536 if (Instruction *Inst = Dep.getInst())
537 ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction());
540 // If the block *is* completely transparent to the load, we need to check
541 // the predecessors of this block. Add them to our worklist.
542 for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
543 DirtyBlocks.push_back(*PI);
550 /// getNonLocalPointerDependency - Perform a full dependency query for an
551 /// access to the specified (non-volatile) memory location, returning the
552 /// set of instructions that either define or clobber the value.
554 /// This method assumes the pointer has a "NonLocal" dependency within its
557 void MemoryDependenceAnalysis::
558 getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB,
559 SmallVectorImpl<NonLocalDepEntry> &Result) {
560 assert(isa<PointerType>(Pointer->getType()) &&
561 "Can't get pointer deps of a non-pointer!");
564 // We know that the pointer value is live into FromBB find the def/clobbers
565 // from presecessors.
566 const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
567 uint64_t PointeeSize = AA->getTypeStoreSize(EltTy);
569 // This is the set of blocks we've inspected, and the pointer we consider in
570 // each block. Because of critical edges, we currently bail out if querying
571 // a block with multiple different pointers. This can happen during PHI
573 DenseMap<BasicBlock*, Value*> Visited;
574 if (!getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB,
575 Result, Visited, true))
578 Result.push_back(std::make_pair(FromBB,
579 MemDepResult::getClobber(FromBB->begin())));
582 /// GetNonLocalInfoForBlock - Compute the memdep value for BB with
583 /// Pointer/PointeeSize using either cached information in Cache or by doing a
584 /// lookup (which may use dirty cache info if available). If we do a lookup,
585 /// add the result to the cache.
586 MemDepResult MemoryDependenceAnalysis::
587 GetNonLocalInfoForBlock(Value *Pointer, uint64_t PointeeSize,
588 bool isLoad, BasicBlock *BB,
589 NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
591 // Do a binary search to see if we already have an entry for this block in
592 // the cache set. If so, find it.
593 NonLocalDepInfo::iterator Entry =
594 std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
595 std::make_pair(BB, MemDepResult()));
596 if (Entry != Cache->begin() && prior(Entry)->first == BB)
599 MemDepResult *ExistingResult = 0;
600 if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
601 ExistingResult = &Entry->second;
603 // If we have a cached entry, and it is non-dirty, use it as the value for
605 if (ExistingResult && !ExistingResult->isDirty()) {
606 ++NumCacheNonLocalPtr;
607 return *ExistingResult;
610 // Otherwise, we have to scan for the value. If we have a dirty cache
611 // entry, start scanning from its position, otherwise we scan from the end
613 BasicBlock::iterator ScanPos = BB->end();
614 if (ExistingResult && ExistingResult->getInst()) {
615 assert(ExistingResult->getInst()->getParent() == BB &&
616 "Instruction invalidated?");
617 ++NumCacheDirtyNonLocalPtr;
618 ScanPos = ExistingResult->getInst();
620 // Eliminating the dirty entry from 'Cache', so update the reverse info.
621 ValueIsLoadPair CacheKey(Pointer, isLoad);
622 RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, CacheKey);
624 ++NumUncacheNonLocalPtr;
627 // Scan the block for the dependency.
628 MemDepResult Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad,
631 // If we had a dirty entry for the block, update it. Otherwise, just add
634 *ExistingResult = Dep;
636 Cache->push_back(std::make_pair(BB, Dep));
638 // If the block has a dependency (i.e. it isn't completely transparent to
639 // the value), remember the reverse association because we just added it
641 if (Dep.isNonLocal())
644 // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
645 // update MemDep when we remove instructions.
646 Instruction *Inst = Dep.getInst();
647 assert(Inst && "Didn't depend on anything?");
648 ValueIsLoadPair CacheKey(Pointer, isLoad);
649 ReverseNonLocalPtrDeps[Inst].insert(CacheKey);
653 /// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain
654 /// number of elements in the array that are already properly ordered. This is
655 /// optimized for the case when only a few entries are added.
657 SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
658 unsigned NumSortedEntries) {
659 switch (Cache.size() - NumSortedEntries) {
661 // done, no new entries.
664 // Two new entries, insert the last one into place.
665 MemoryDependenceAnalysis::NonLocalDepEntry Val = Cache.back();
667 MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
668 std::upper_bound(Cache.begin(), Cache.end()-1, Val);
669 Cache.insert(Entry, Val);
673 // One new entry, Just insert the new value at the appropriate position.
674 if (Cache.size() != 1) {
675 MemoryDependenceAnalysis::NonLocalDepEntry Val = Cache.back();
677 MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
678 std::upper_bound(Cache.begin(), Cache.end(), Val);
679 Cache.insert(Entry, Val);
683 // Added many values, do a full scale sort.
684 std::sort(Cache.begin(), Cache.end());
689 /// isPHITranslatable - Return true if the specified computation is derived from
690 /// a PHI node in the current block and if it is simple enough for us to handle.
691 static bool isPHITranslatable(Instruction *Inst) {
692 if (isa<PHINode>(Inst))
695 // We can handle bitcast of a PHI, but the PHI needs to be in the same block
697 if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
698 Instruction *OpI = dyn_cast<Instruction>(BC->getOperand(0));
699 if (OpI == 0 || OpI->getParent() != Inst->getParent())
701 return isPHITranslatable(OpI);
704 // We can translate a GEP if all of its operands defined in this block are phi
706 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
707 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
708 Instruction *OpI = dyn_cast<Instruction>(GEP->getOperand(i));
709 if (OpI == 0 || OpI->getParent() != Inst->getParent())
712 if (!isPHITranslatable(OpI))
718 if (Inst->getOpcode() == Instruction::Add &&
719 isa<ConstantInt>(Inst->getOperand(1))) {
720 Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
721 if (OpI == 0 || OpI->getParent() != Inst->getParent())
723 return isPHITranslatable(OpI);
726 // cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
727 // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
728 // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
733 /// GetPHITranslatedValue - Given a computation that satisfied the
734 /// isPHITranslatable predicate, see if we can translate the computation into
735 /// the specified predecessor block. If so, return that value.
736 Value *MemoryDependenceAnalysis::
737 GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
738 const TargetData *TD) const {
739 // If the input value is not an instruction, or if it is not defined in CurBB,
740 // then we don't need to phi translate it.
741 Instruction *Inst = dyn_cast<Instruction>(InVal);
742 if (Inst == 0 || Inst->getParent() != CurBB)
745 if (PHINode *PN = dyn_cast<PHINode>(Inst))
746 return PN->getIncomingValueForBlock(Pred);
748 // Handle bitcast of PHI.
749 if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
750 // PHI translate the input operand.
751 Value *PHIIn = GetPHITranslatedValue(BC->getOperand(0), CurBB, Pred, TD);
752 if (PHIIn == 0) return 0;
754 // Constants are trivial to phi translate.
755 if (Constant *C = dyn_cast<Constant>(PHIIn))
756 return ConstantExpr::getBitCast(C, BC->getType());
758 // Otherwise we have to see if a bitcasted version of the incoming pointer
759 // is available. If so, we can use it, otherwise we have to fail.
760 for (Value::use_iterator UI = PHIIn->use_begin(), E = PHIIn->use_end();
762 if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI))
763 if (BCI->getType() == BC->getType())
769 // Handle getelementptr with at least one PHI translatable operand.
770 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
771 SmallVector<Value*, 8> GEPOps;
772 BasicBlock *CurBB = GEP->getParent();
773 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
774 Value *GEPOp = GEP->getOperand(i);
775 // No PHI translation is needed of operands whose values are live in to
776 // the predecessor block.
777 if (!isa<Instruction>(GEPOp) ||
778 cast<Instruction>(GEPOp)->getParent() != CurBB) {
779 GEPOps.push_back(GEPOp);
783 // If the operand is a phi node, do phi translation.
784 Value *InOp = GetPHITranslatedValue(GEPOp, CurBB, Pred, TD);
785 if (InOp == 0) return 0;
787 GEPOps.push_back(InOp);
790 // Simplify the GEP to handle 'gep x, 0' -> x etc.
791 if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD))
794 // Scan to see if we have this GEP available.
795 Value *APHIOp = GEPOps[0];
796 for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
798 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI))
799 if (GEPI->getType() == GEP->getType() &&
800 GEPI->getNumOperands() == GEPOps.size() &&
801 GEPI->getParent()->getParent() == CurBB->getParent()) {
802 bool Mismatch = false;
803 for (unsigned i = 0, e = GEPOps.size(); i != e; ++i)
804 if (GEPI->getOperand(i) != GEPOps[i]) {
815 // Handle add with a constant RHS.
816 if (Inst->getOpcode() == Instruction::Add &&
817 isa<ConstantInt>(Inst->getOperand(1))) {
818 // PHI translate the LHS.
820 Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
821 Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
822 bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
823 bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
825 if (OpI == 0 || OpI->getParent() != Inst->getParent())
826 LHS = Inst->getOperand(0);
828 LHS = GetPHITranslatedValue(Inst->getOperand(0), CurBB, Pred, TD);
833 // If the PHI translated LHS is an add of a constant, fold the immediates.
834 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
835 if (BOp->getOpcode() == Instruction::Add)
836 if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
837 LHS = BOp->getOperand(0);
838 RHS = ConstantExpr::getAdd(RHS, CI);
839 isNSW = isNUW = false;
842 // See if the add simplifies away.
843 if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, TD))
846 // Otherwise, see if we have this add available somewhere.
847 for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
849 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI))
850 if (BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
851 BO->getParent()->getParent() == CurBB->getParent())
861 /// GetAvailablePHITranslatePointer - Return the value computed by
862 /// PHITranslatePointer if it dominates PredBB, otherwise return null.
863 Value *MemoryDependenceAnalysis::
864 GetAvailablePHITranslatedValue(Value *V,
865 BasicBlock *CurBB, BasicBlock *PredBB,
866 const TargetData *TD,
867 const DominatorTree &DT) const {
868 // See if PHI translation succeeds.
869 V = GetPHITranslatedValue(V, CurBB, PredBB, TD);
870 if (V == 0) return 0;
872 // Make sure the value is live in the predecessor.
873 if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
874 if (!DT.dominates(Inst->getParent(), PredBB))
880 /// InsertPHITranslatedPointer - Insert a computation of the PHI translated
881 /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
884 /// This is only called when PHITranslatePointer returns a value that doesn't
885 /// dominate the block, so we don't need to handle the trivial cases here.
886 Value *MemoryDependenceAnalysis::
887 InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
888 BasicBlock *PredBB, const TargetData *TD,
889 const DominatorTree &DT) const {
890 // See if we have a version of this value already available and dominating
891 // PredBB. If so, there is no need to insert a new copy.
892 if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT))
895 // If we don't have an available version of this value, it must be an
897 Instruction *Inst = cast<Instruction>(InVal);
899 // Handle bitcast of PHI translatable value.
900 if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
901 Value *OpVal = InsertPHITranslatedPointer(BC->getOperand(0),
902 CurBB, PredBB, TD, DT);
903 if (OpVal == 0) return 0;
905 // Otherwise insert a bitcast at the end of PredBB.
906 return new BitCastInst(OpVal, InVal->getType(),
907 InVal->getName()+".phi.trans.insert",
908 PredBB->getTerminator());
911 // Handle getelementptr with at least one PHI operand.
912 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
913 SmallVector<Value*, 8> GEPOps;
914 BasicBlock *CurBB = GEP->getParent();
915 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
916 Value *OpVal = InsertPHITranslatedPointer(GEP->getOperand(i),
917 CurBB, PredBB, TD, DT);
918 if (OpVal == 0) return 0;
919 GEPOps.push_back(OpVal);
922 GetElementPtrInst *Result =
923 GetElementPtrInst::Create(GEPOps[0], GEPOps.begin()+1, GEPOps.end(),
924 InVal->getName()+".phi.trans.insert",
925 PredBB->getTerminator());
926 Result->setIsInBounds(GEP->isInBounds());
931 // FIXME: This code works, but it is unclear that we actually want to insert
932 // a big chain of computation in order to make a value available in a block.
933 // This needs to be evaluated carefully to consider its cost trade offs.
935 // Handle add with a constant RHS.
936 if (Inst->getOpcode() == Instruction::Add &&
937 isa<ConstantInt>(Inst->getOperand(1))) {
938 // PHI translate the LHS.
939 Value *OpVal = InsertPHITranslatedPointer(Inst->getOperand(0),
940 CurBB, PredBB, TD, DT);
941 if (OpVal == 0) return 0;
943 BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1),
944 InVal->getName()+".phi.trans.insert",
945 PredBB->getTerminator());
946 Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap());
947 Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap());
955 /// getNonLocalPointerDepFromBB - Perform a dependency query based on
956 /// pointer/pointeesize starting at the end of StartBB. Add any clobber/def
957 /// results to the results vector and keep track of which blocks are visited in
960 /// This has special behavior for the first block queries (when SkipFirstBlock
961 /// is true). In this special case, it ignores the contents of the specified
962 /// block and starts returning dependence info for its predecessors.
964 /// This function returns false on success, or true to indicate that it could
965 /// not compute dependence information for some reason. This should be treated
966 /// as a clobber dependence on the first instruction in the predecessor block.
967 bool MemoryDependenceAnalysis::
968 getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
969 bool isLoad, BasicBlock *StartBB,
970 SmallVectorImpl<NonLocalDepEntry> &Result,
971 DenseMap<BasicBlock*, Value*> &Visited,
972 bool SkipFirstBlock) {
974 // Look up the cached info for Pointer.
975 ValueIsLoadPair CacheKey(Pointer, isLoad);
977 std::pair<BBSkipFirstBlockPair, NonLocalDepInfo> *CacheInfo =
978 &NonLocalPointerDeps[CacheKey];
979 NonLocalDepInfo *Cache = &CacheInfo->second;
981 // If we have valid cached information for exactly the block we are
982 // investigating, just return it with no recomputation.
983 if (CacheInfo->first == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
984 // We have a fully cached result for this query then we can just return the
985 // cached results and populate the visited set. However, we have to verify
986 // that we don't already have conflicting results for these blocks. Check
987 // to ensure that if a block in the results set is in the visited set that
988 // it was for the same pointer query.
989 if (!Visited.empty()) {
990 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
992 DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->first);
993 if (VI == Visited.end() || VI->second == Pointer) continue;
995 // We have a pointer mismatch in a block. Just return clobber, saying
996 // that something was clobbered in this result. We could also do a
997 // non-fully cached query, but there is little point in doing this.
1002 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
1004 Visited.insert(std::make_pair(I->first, Pointer));
1005 if (!I->second.isNonLocal())
1006 Result.push_back(*I);
1008 ++NumCacheCompleteNonLocalPtr;
1012 // Otherwise, either this is a new block, a block with an invalid cache
1013 // pointer or one that we're about to invalidate by putting more info into it
1014 // than its valid cache info. If empty, the result will be valid cache info,
1015 // otherwise it isn't.
1017 CacheInfo->first = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
1019 CacheInfo->first = BBSkipFirstBlockPair();
1021 SmallVector<BasicBlock*, 32> Worklist;
1022 Worklist.push_back(StartBB);
1024 // Keep track of the entries that we know are sorted. Previously cached
1025 // entries will all be sorted. The entries we add we only sort on demand (we
1026 // don't insert every element into its sorted position). We know that we
1027 // won't get any reuse from currently inserted values, because we don't
1028 // revisit blocks after we insert info for them.
1029 unsigned NumSortedEntries = Cache->size();
1030 DEBUG(AssertSorted(*Cache));
1032 while (!Worklist.empty()) {
1033 BasicBlock *BB = Worklist.pop_back_val();
1035 // Skip the first block if we have it.
1036 if (!SkipFirstBlock) {
1037 // Analyze the dependency of *Pointer in FromBB. See if we already have
1039 assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
1041 // Get the dependency info for Pointer in BB. If we have cached
1042 // information, we will use it, otherwise we compute it.
1043 DEBUG(AssertSorted(*Cache, NumSortedEntries));
1044 MemDepResult Dep = GetNonLocalInfoForBlock(Pointer, PointeeSize, isLoad,
1045 BB, Cache, NumSortedEntries);
1047 // If we got a Def or Clobber, add this to the list of results.
1048 if (!Dep.isNonLocal()) {
1049 Result.push_back(NonLocalDepEntry(BB, Dep));
1054 // If 'Pointer' is an instruction defined in this block, then we need to do
1055 // phi translation to change it into a value live in the predecessor block.
1056 // If phi translation fails, then we can't continue dependence analysis.
1057 Instruction *PtrInst = dyn_cast<Instruction>(Pointer);
1058 bool NeedsPHITranslation = PtrInst && PtrInst->getParent() == BB;
1060 // If no PHI translation is needed, just add all the predecessors of this
1061 // block to scan them as well.
1062 if (!NeedsPHITranslation) {
1063 SkipFirstBlock = false;
1064 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
1065 // Verify that we haven't looked at this block yet.
1066 std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
1067 InsertRes = Visited.insert(std::make_pair(*PI, Pointer));
1068 if (InsertRes.second) {
1069 // First time we've looked at *PI.
1070 Worklist.push_back(*PI);
1074 // If we have seen this block before, but it was with a different
1075 // pointer then we have a phi translation failure and we have to treat
1076 // this as a clobber.
1077 if (InsertRes.first->second != Pointer)
1078 goto PredTranslationFailure;
1083 // If we do need to do phi translation, then there are a bunch of different
1084 // cases, because we have to find a Value* live in the predecessor block. We
1085 // know that PtrInst is defined in this block at least.
1087 // We may have added values to the cache list before this PHI translation.
1088 // If so, we haven't done anything to ensure that the cache remains sorted.
1089 // Sort it now (if needed) so that recursive invocations of
1090 // getNonLocalPointerDepFromBB and other routines that could reuse the cache
1091 // value will only see properly sorted cache arrays.
1092 if (Cache && NumSortedEntries != Cache->size()) {
1093 SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
1094 NumSortedEntries = Cache->size();
1097 // If this is a computation derived from a PHI node, use the suitably
1098 // translated incoming values for each pred as the phi translated version.
1099 if (!isPHITranslatable(PtrInst))
1100 goto PredTranslationFailure;
1104 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
1105 BasicBlock *Pred = *PI;
1106 // Get the PHI translated pointer in this predecessor. This can fail and
1107 // return null if not translatable.
1108 Value *PredPtr = GetPHITranslatedValue(PtrInst, BB, Pred, TD);
1110 // Check to see if we have already visited this pred block with another
1111 // pointer. If so, we can't do this lookup. This failure can occur
1112 // with PHI translation when a critical edge exists and the PHI node in
1113 // the successor translates to a pointer value different than the
1114 // pointer the block was first analyzed with.
1115 std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
1116 InsertRes = Visited.insert(std::make_pair(Pred, PredPtr));
1118 if (!InsertRes.second) {
1119 // If the predecessor was visited with PredPtr, then we already did
1120 // the analysis and can ignore it.
1121 if (InsertRes.first->second == PredPtr)
1124 // Otherwise, the block was previously analyzed with a different
1125 // pointer. We can't represent the result of this case, so we just
1126 // treat this as a phi translation failure.
1127 goto PredTranslationFailure;
1130 // If PHI translation was unable to find an available pointer in this
1131 // predecessor, then we have to assume that the pointer is clobbered in
1132 // that predecessor. We can still do PRE of the load, which would insert
1133 // a computation of the pointer in this predecessor.
1135 Result.push_back(NonLocalDepEntry(Pred,
1136 MemDepResult::getClobber(Pred->getTerminator())));
1140 // FIXME: it is entirely possible that PHI translating will end up with
1141 // the same value. Consider PHI translating something like:
1142 // X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need*
1143 // to recurse here, pedantically speaking.
1145 // If we have a problem phi translating, fall through to the code below
1146 // to handle the failure condition.
1147 if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred,
1149 goto PredTranslationFailure;
1152 // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
1153 CacheInfo = &NonLocalPointerDeps[CacheKey];
1154 Cache = &CacheInfo->second;
1155 NumSortedEntries = Cache->size();
1157 // Since we did phi translation, the "Cache" set won't contain all of the
1158 // results for the query. This is ok (we can still use it to accelerate
1159 // specific block queries) but we can't do the fastpath "return all
1160 // results from the set" Clear out the indicator for this.
1161 CacheInfo->first = BBSkipFirstBlockPair();
1162 SkipFirstBlock = false;
1165 PredTranslationFailure:
1168 // Refresh the CacheInfo/Cache pointer if it got invalidated.
1169 CacheInfo = &NonLocalPointerDeps[CacheKey];
1170 Cache = &CacheInfo->second;
1171 NumSortedEntries = Cache->size();
1174 // Since we did phi translation, the "Cache" set won't contain all of the
1175 // results for the query. This is ok (we can still use it to accelerate
1176 // specific block queries) but we can't do the fastpath "return all
1177 // results from the set" Clear out the indicator for this.
1178 CacheInfo->first = BBSkipFirstBlockPair();
1180 // If *nothing* works, mark the pointer as being clobbered by the first
1181 // instruction in this block.
1183 // If this is the magic first block, return this as a clobber of the whole
1184 // incoming value. Since we can't phi translate to one of the predecessors,
1185 // we have to bail out.
1189 for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) {
1190 assert(I != Cache->rend() && "Didn't find current block??");
1194 assert(I->second.isNonLocal() &&
1195 "Should only be here with transparent block");
1196 I->second = MemDepResult::getClobber(BB->begin());
1197 ReverseNonLocalPtrDeps[BB->begin()].insert(CacheKey);
1198 Result.push_back(*I);
1203 // Okay, we're done now. If we added new values to the cache, re-sort it.
1204 SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
1205 DEBUG(AssertSorted(*Cache));
1209 /// RemoveCachedNonLocalPointerDependencies - If P exists in
1210 /// CachedNonLocalPointerInfo, remove it.
1211 void MemoryDependenceAnalysis::
1212 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
1213 CachedNonLocalPointerInfo::iterator It =
1214 NonLocalPointerDeps.find(P);
1215 if (It == NonLocalPointerDeps.end()) return;
1217 // Remove all of the entries in the BB->val map. This involves removing
1218 // instructions from the reverse map.
1219 NonLocalDepInfo &PInfo = It->second.second;
1221 for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
1222 Instruction *Target = PInfo[i].second.getInst();
1223 if (Target == 0) continue; // Ignore non-local dep results.
1224 assert(Target->getParent() == PInfo[i].first);
1226 // Eliminating the dirty entry from 'Cache', so update the reverse info.
1227 RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P);
1230 // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
1231 NonLocalPointerDeps.erase(It);
1235 /// invalidateCachedPointerInfo - This method is used to invalidate cached
1236 /// information about the specified pointer, because it may be too
1237 /// conservative in memdep. This is an optional call that can be used when
1238 /// the client detects an equivalence between the pointer and some other
1239 /// value and replaces the other value with ptr. This can make Ptr available
1240 /// in more places that cached info does not necessarily keep.
1241 void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
1242 // If Ptr isn't really a pointer, just ignore it.
1243 if (!isa<PointerType>(Ptr->getType())) return;
1244 // Flush store info for the pointer.
1245 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
1246 // Flush load info for the pointer.
1247 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
1250 /// removeInstruction - Remove an instruction from the dependence analysis,
1251 /// updating the dependence of instructions that previously depended on it.
1252 /// This method attempts to keep the cache coherent using the reverse map.
1253 void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
1254 // Walk through the Non-local dependencies, removing this one as the value
1255 // for any cached queries.
1256 NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
1257 if (NLDI != NonLocalDeps.end()) {
1258 NonLocalDepInfo &BlockMap = NLDI->second.first;
1259 for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
1261 if (Instruction *Inst = DI->second.getInst())
1262 RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
1263 NonLocalDeps.erase(NLDI);
1266 // If we have a cached local dependence query for this instruction, remove it.
1268 LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
1269 if (LocalDepEntry != LocalDeps.end()) {
1270 // Remove us from DepInst's reverse set now that the local dep info is gone.
1271 if (Instruction *Inst = LocalDepEntry->second.getInst())
1272 RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
1274 // Remove this local dependency info.
1275 LocalDeps.erase(LocalDepEntry);
1278 // If we have any cached pointer dependencies on this instruction, remove
1279 // them. If the instruction has non-pointer type, then it can't be a pointer
1282 // Remove it from both the load info and the store info. The instruction
1283 // can't be in either of these maps if it is non-pointer.
1284 if (isa<PointerType>(RemInst->getType())) {
1285 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
1286 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
1289 // Loop over all of the things that depend on the instruction we're removing.
1291 SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
1293 // If we find RemInst as a clobber or Def in any of the maps for other values,
1294 // we need to replace its entry with a dirty version of the instruction after
1295 // it. If RemInst is a terminator, we use a null dirty value.
1297 // Using a dirty version of the instruction after RemInst saves having to scan
1298 // the entire block to get to this point.
1299 MemDepResult NewDirtyVal;
1300 if (!RemInst->isTerminator())
1301 NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
1303 ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
1304 if (ReverseDepIt != ReverseLocalDeps.end()) {
1305 SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
1306 // RemInst can't be the terminator if it has local stuff depending on it.
1307 assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
1308 "Nothing can locally depend on a terminator");
1310 for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
1311 E = ReverseDeps.end(); I != E; ++I) {
1312 Instruction *InstDependingOnRemInst = *I;
1313 assert(InstDependingOnRemInst != RemInst &&
1314 "Already removed our local dep info");
1316 LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
1318 // Make sure to remember that new things depend on NewDepInst.
1319 assert(NewDirtyVal.getInst() && "There is no way something else can have "
1320 "a local dep on this if it is a terminator!");
1321 ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(),
1322 InstDependingOnRemInst));
1325 ReverseLocalDeps.erase(ReverseDepIt);
1327 // Add new reverse deps after scanning the set, to avoid invalidating the
1328 // 'ReverseDeps' reference.
1329 while (!ReverseDepsToAdd.empty()) {
1330 ReverseLocalDeps[ReverseDepsToAdd.back().first]
1331 .insert(ReverseDepsToAdd.back().second);
1332 ReverseDepsToAdd.pop_back();
1336 ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
1337 if (ReverseDepIt != ReverseNonLocalDeps.end()) {
1338 SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
1339 for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
1341 assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
1343 PerInstNLInfo &INLD = NonLocalDeps[*I];
1344 // The information is now dirty!
1347 for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
1348 DE = INLD.first.end(); DI != DE; ++DI) {
1349 if (DI->second.getInst() != RemInst) continue;
1351 // Convert to a dirty entry for the subsequent instruction.
1352 DI->second = NewDirtyVal;
1354 if (Instruction *NextI = NewDirtyVal.getInst())
1355 ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
1359 ReverseNonLocalDeps.erase(ReverseDepIt);
1361 // Add new reverse deps after scanning the set, to avoid invalidating 'Set'
1362 while (!ReverseDepsToAdd.empty()) {
1363 ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
1364 .insert(ReverseDepsToAdd.back().second);
1365 ReverseDepsToAdd.pop_back();
1369 // If the instruction is in ReverseNonLocalPtrDeps then it appears as a
1370 // value in the NonLocalPointerDeps info.
1371 ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
1372 ReverseNonLocalPtrDeps.find(RemInst);
1373 if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
1374 SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second;
1375 SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
1377 for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(),
1378 E = Set.end(); I != E; ++I) {
1379 ValueIsLoadPair P = *I;
1380 assert(P.getPointer() != RemInst &&
1381 "Already removed NonLocalPointerDeps info for RemInst");
1383 NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].second;
1385 // The cache is not valid for any specific block anymore.
1386 NonLocalPointerDeps[P].first = BBSkipFirstBlockPair();
1388 // Update any entries for RemInst to use the instruction after it.
1389 for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
1391 if (DI->second.getInst() != RemInst) continue;
1393 // Convert to a dirty entry for the subsequent instruction.
1394 DI->second = NewDirtyVal;
1396 if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
1397 ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
1400 // Re-sort the NonLocalDepInfo. Changing the dirty entry to its
1401 // subsequent value may invalidate the sortedness.
1402 std::sort(NLPDI.begin(), NLPDI.end());
1405 ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
1407 while (!ReversePtrDepsToAdd.empty()) {
1408 ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
1409 .insert(ReversePtrDepsToAdd.back().second);
1410 ReversePtrDepsToAdd.pop_back();
1415 assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
1416 AA->deleteValue(RemInst);
1417 DEBUG(verifyRemoved(RemInst));
1419 /// verifyRemoved - Verify that the specified instruction does not occur
1420 /// in our internal data structures.
1421 void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
1422 for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
1423 E = LocalDeps.end(); I != E; ++I) {
1424 assert(I->first != D && "Inst occurs in data structures");
1425 assert(I->second.getInst() != D &&
1426 "Inst occurs in data structures");
1429 for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
1430 E = NonLocalPointerDeps.end(); I != E; ++I) {
1431 assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
1432 const NonLocalDepInfo &Val = I->second.second;
1433 for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
1435 assert(II->second.getInst() != D && "Inst occurs as NLPD value");
1438 for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
1439 E = NonLocalDeps.end(); I != E; ++I) {
1440 assert(I->first != D && "Inst occurs in data structures");
1441 const PerInstNLInfo &INLD = I->second;
1442 for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
1443 EE = INLD.first.end(); II != EE; ++II)
1444 assert(II->second.getInst() != D && "Inst occurs in data structures");
1447 for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
1448 E = ReverseLocalDeps.end(); I != E; ++I) {
1449 assert(I->first != D && "Inst occurs in data structures");
1450 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
1451 EE = I->second.end(); II != EE; ++II)
1452 assert(*II != D && "Inst occurs in data structures");
1455 for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
1456 E = ReverseNonLocalDeps.end();
1458 assert(I->first != D && "Inst occurs in data structures");
1459 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
1460 EE = I->second.end(); II != EE; ++II)
1461 assert(*II != D && "Inst occurs in data structures");
1464 for (ReverseNonLocalPtrDepTy::const_iterator
1465 I = ReverseNonLocalPtrDeps.begin(),
1466 E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
1467 assert(I->first != D && "Inst occurs in rev NLPD map");
1469 for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(),
1470 E = I->second.end(); II != E; ++II)
1471 assert(*II != ValueIsLoadPair(D, false) &&
1472 *II != ValueIsLoadPair(D, true) &&
1473 "Inst occurs in ReverseNonLocalPtrDeps map");