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) {
188 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
189 // Debug intrinsics don't cause dependences.
190 if (isa<DbgInfoIntrinsic>(Inst)) continue;
192 // If we pass an invariant-end marker, then we've just entered an
193 // invariant region and can start ignoring dependencies.
194 if (II->getIntrinsicID() == Intrinsic::invariant_end) {
195 // FIXME: This only considers queries directly on the invariant-tagged
196 // pointer, not on query pointers that are indexed off of them. It'd
197 // be nice to handle that at some point.
198 AliasAnalysis::AliasResult R =
199 AA->alias(II->getOperand(3), ~0U, MemPtr, ~0U);
200 if (R == AliasAnalysis::MustAlias) {
201 InvariantTag = II->getOperand(1);
205 // If we reach a lifetime begin or end marker, then the query ends here
206 // because the value is undefined.
207 } else if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
208 // FIXME: This only considers queries directly on the invariant-tagged
209 // pointer, not on query pointers that are indexed off of them. It'd
210 // be nice to handle that at some point.
211 AliasAnalysis::AliasResult R =
212 AA->alias(II->getOperand(2), ~0U, MemPtr, ~0U);
213 if (R == AliasAnalysis::MustAlias)
214 return MemDepResult::getDef(II);
218 // If we're querying on a load and we're in an invariant region, we're done
219 // at this point. Nothing a load depends on can live in an invariant region.
220 if (isLoad && InvariantTag) continue;
222 // Values depend on loads if the pointers are must aliased. This means that
223 // a load depends on another must aliased load from the same value.
224 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
225 Value *Pointer = LI->getPointerOperand();
226 uint64_t PointerSize = AA->getTypeStoreSize(LI->getType());
228 // If we found a pointer, check if it could be the same as our pointer.
229 AliasAnalysis::AliasResult R =
230 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
231 if (R == AliasAnalysis::NoAlias)
234 // May-alias loads don't depend on each other without a dependence.
235 if (isLoad && R == AliasAnalysis::MayAlias)
237 // Stores depend on may and must aliased loads, loads depend on must-alias
239 return MemDepResult::getDef(Inst);
242 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
243 // There can't be stores to the value we care about inside an
245 if (InvariantTag) continue;
247 // If alias analysis can tell that this store is guaranteed to not modify
248 // the query pointer, ignore it. Use getModRefInfo to handle cases where
249 // the query pointer points to constant memory etc.
250 if (AA->getModRefInfo(SI, MemPtr, MemSize) == AliasAnalysis::NoModRef)
253 // Ok, this store might clobber the query pointer. Check to see if it is
254 // a must alias: in this case, we want to return this as a def.
255 Value *Pointer = SI->getPointerOperand();
256 uint64_t PointerSize = AA->getTypeStoreSize(SI->getOperand(0)->getType());
258 // If we found a pointer, check if it could be the same as our pointer.
259 AliasAnalysis::AliasResult R =
260 AA->alias(Pointer, PointerSize, MemPtr, MemSize);
262 if (R == AliasAnalysis::NoAlias)
264 if (R == AliasAnalysis::MayAlias)
265 return MemDepResult::getClobber(Inst);
266 return MemDepResult::getDef(Inst);
269 // If this is an allocation, and if we know that the accessed pointer is to
270 // the allocation, return Def. This means that there is no dependence and
271 // the access can be optimized based on that. For example, a load could
273 // Note: Only determine this to be a malloc if Inst is the malloc call, not
274 // a subsequent bitcast of the malloc call result. There can be stores to
275 // the malloced memory between the malloc call and its bitcast uses, and we
276 // need to continue scanning until the malloc call.
277 if (isa<AllocaInst>(Inst) || extractMallocCall(Inst)) {
278 Value *AccessPtr = MemPtr->getUnderlyingObject();
280 if (AccessPtr == Inst ||
281 AA->alias(Inst, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
282 return MemDepResult::getDef(Inst);
286 // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
287 switch (AA->getModRefInfo(Inst, MemPtr, MemSize)) {
288 case AliasAnalysis::NoModRef:
289 // If the call has no effect on the queried pointer, just ignore it.
291 case AliasAnalysis::Mod:
292 // If we're in an invariant region, we can ignore calls that ONLY
293 // modify the pointer.
294 if (InvariantTag) continue;
295 return MemDepResult::getClobber(Inst);
296 case AliasAnalysis::Ref:
297 // If the call is known to never store to the pointer, and if this is a
298 // load query, we can safely ignore it (scan past it).
302 // Otherwise, there is a potential dependence. Return a clobber.
303 return MemDepResult::getClobber(Inst);
307 // No dependence found. If this is the entry block of the function, it is a
308 // clobber, otherwise it is non-local.
309 if (BB != &BB->getParent()->getEntryBlock())
310 return MemDepResult::getNonLocal();
311 return MemDepResult::getClobber(ScanIt);
314 /// getDependency - Return the instruction on which a memory operation
316 MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
317 Instruction *ScanPos = QueryInst;
319 // Check for a cached result
320 MemDepResult &LocalCache = LocalDeps[QueryInst];
322 // If the cached entry is non-dirty, just return it. Note that this depends
323 // on MemDepResult's default constructing to 'dirty'.
324 if (!LocalCache.isDirty())
327 // Otherwise, if we have a dirty entry, we know we can start the scan at that
328 // instruction, which may save us some work.
329 if (Instruction *Inst = LocalCache.getInst()) {
332 RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
335 BasicBlock *QueryParent = QueryInst->getParent();
338 uint64_t MemSize = 0;
341 if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
342 // No dependence found. If this is the entry block of the function, it is a
343 // clobber, otherwise it is non-local.
344 if (QueryParent != &QueryParent->getParent()->getEntryBlock())
345 LocalCache = MemDepResult::getNonLocal();
347 LocalCache = MemDepResult::getClobber(QueryInst);
348 } else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
349 // If this is a volatile store, don't mess around with it. Just return the
350 // previous instruction as a clobber.
351 if (SI->isVolatile())
352 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
354 MemPtr = SI->getPointerOperand();
355 MemSize = AA->getTypeStoreSize(SI->getOperand(0)->getType());
357 } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
358 // If this is a volatile load, don't mess around with it. Just return the
359 // previous instruction as a clobber.
360 if (LI->isVolatile())
361 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
363 MemPtr = LI->getPointerOperand();
364 MemSize = AA->getTypeStoreSize(LI->getType());
366 } else if (isFreeCall(QueryInst)) {
367 MemPtr = QueryInst->getOperand(1);
368 // calls to free() erase the entire structure, not just a field.
370 } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
371 int IntrinsicID = 0; // Intrinsic IDs start at 1.
372 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst))
373 IntrinsicID = II->getIntrinsicID();
375 switch (IntrinsicID) {
376 case Intrinsic::lifetime_start:
377 case Intrinsic::lifetime_end:
378 case Intrinsic::invariant_start:
379 MemPtr = QueryInst->getOperand(2);
380 MemSize = cast<ConstantInt>(QueryInst->getOperand(1))->getZExtValue();
382 case Intrinsic::invariant_end:
383 MemPtr = QueryInst->getOperand(3);
384 MemSize = cast<ConstantInt>(QueryInst->getOperand(2))->getZExtValue();
387 CallSite QueryCS = CallSite::get(QueryInst);
388 bool isReadOnly = AA->onlyReadsMemory(QueryCS);
389 LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
393 // Non-memory instruction.
394 LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
397 // If we need to do a pointer scan, make it happen.
399 bool isLoad = !QueryInst->mayWriteToMemory();
400 if (IntrinsicInst *II = dyn_cast<MemoryUseIntrinsic>(QueryInst)) {
401 isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_end;
403 LocalCache = getPointerDependencyFrom(MemPtr, MemSize, isLoad, ScanPos,
407 // Remember the result!
408 if (Instruction *I = LocalCache.getInst())
409 ReverseLocalDeps[I].insert(QueryInst);
415 /// AssertSorted - This method is used when -debug is specified to verify that
416 /// cache arrays are properly kept sorted.
417 static void AssertSorted(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
419 if (Count == -1) Count = Cache.size();
420 if (Count == 0) return;
422 for (unsigned i = 1; i != unsigned(Count); ++i)
423 assert(Cache[i-1] <= Cache[i] && "Cache isn't sorted!");
427 /// getNonLocalCallDependency - Perform a full dependency query for the
428 /// specified call, returning the set of blocks that the value is
429 /// potentially live across. The returned set of results will include a
430 /// "NonLocal" result for all blocks where the value is live across.
432 /// This method assumes the instruction returns a "NonLocal" dependency
433 /// within its own block.
435 /// This returns a reference to an internal data structure that may be
436 /// invalidated on the next non-local query or when an instruction is
437 /// removed. Clients must copy this data if they want it around longer than
439 const MemoryDependenceAnalysis::NonLocalDepInfo &
440 MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
441 assert(getDependency(QueryCS.getInstruction()).isNonLocal() &&
442 "getNonLocalCallDependency should only be used on calls with non-local deps!");
443 PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()];
444 NonLocalDepInfo &Cache = CacheP.first;
446 /// DirtyBlocks - This is the set of blocks that need to be recomputed. In
447 /// the cached case, this can happen due to instructions being deleted etc. In
448 /// the uncached case, this starts out as the set of predecessors we care
450 SmallVector<BasicBlock*, 32> DirtyBlocks;
452 if (!Cache.empty()) {
453 // Okay, we have a cache entry. If we know it is not dirty, just return it
454 // with no computation.
455 if (!CacheP.second) {
460 // If we already have a partially computed set of results, scan them to
461 // determine what is dirty, seeding our initial DirtyBlocks worklist.
462 for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
464 if (I->second.isDirty())
465 DirtyBlocks.push_back(I->first);
467 // Sort the cache so that we can do fast binary search lookups below.
468 std::sort(Cache.begin(), Cache.end());
470 ++NumCacheDirtyNonLocal;
471 //cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
472 // << Cache.size() << " cached: " << *QueryInst;
474 // Seed DirtyBlocks with each of the preds of QueryInst's block.
475 BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
476 for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
477 DirtyBlocks.push_back(*PI);
478 NumUncacheNonLocal++;
481 // isReadonlyCall - If this is a read-only call, we can be more aggressive.
482 bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
484 SmallPtrSet<BasicBlock*, 64> Visited;
486 unsigned NumSortedEntries = Cache.size();
487 DEBUG(AssertSorted(Cache));
489 // Iterate while we still have blocks to update.
490 while (!DirtyBlocks.empty()) {
491 BasicBlock *DirtyBB = DirtyBlocks.back();
492 DirtyBlocks.pop_back();
494 // Already processed this block?
495 if (!Visited.insert(DirtyBB))
498 // Do a binary search to see if we already have an entry for this block in
499 // the cache set. If so, find it.
500 DEBUG(AssertSorted(Cache, NumSortedEntries));
501 NonLocalDepInfo::iterator Entry =
502 std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
503 std::make_pair(DirtyBB, MemDepResult()));
504 if (Entry != Cache.begin() && prior(Entry)->first == DirtyBB)
507 MemDepResult *ExistingResult = 0;
508 if (Entry != Cache.begin()+NumSortedEntries &&
509 Entry->first == DirtyBB) {
510 // If we already have an entry, and if it isn't already dirty, the block
512 if (!Entry->second.isDirty())
515 // Otherwise, remember this slot so we can update the value.
516 ExistingResult = &Entry->second;
519 // If the dirty entry has a pointer, start scanning from it so we don't have
520 // to rescan the entire block.
521 BasicBlock::iterator ScanPos = DirtyBB->end();
522 if (ExistingResult) {
523 if (Instruction *Inst = ExistingResult->getInst()) {
525 // We're removing QueryInst's use of Inst.
526 RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
527 QueryCS.getInstruction());
531 // Find out if this block has a local dependency for QueryInst.
534 if (ScanPos != DirtyBB->begin()) {
535 Dep = getCallSiteDependencyFrom(QueryCS, isReadonlyCall,ScanPos, DirtyBB);
536 } else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) {
537 // No dependence found. If this is the entry block of the function, it is
538 // a clobber, otherwise it is non-local.
539 Dep = MemDepResult::getNonLocal();
541 Dep = MemDepResult::getClobber(ScanPos);
544 // If we had a dirty entry for the block, update it. Otherwise, just add
547 *ExistingResult = Dep;
549 Cache.push_back(std::make_pair(DirtyBB, Dep));
551 // If the block has a dependency (i.e. it isn't completely transparent to
552 // the value), remember the association!
553 if (!Dep.isNonLocal()) {
554 // Keep the ReverseNonLocalDeps map up to date so we can efficiently
555 // update this when we remove instructions.
556 if (Instruction *Inst = Dep.getInst())
557 ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction());
560 // If the block *is* completely transparent to the load, we need to check
561 // the predecessors of this block. Add them to our worklist.
562 for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
563 DirtyBlocks.push_back(*PI);
570 /// getNonLocalPointerDependency - Perform a full dependency query for an
571 /// access to the specified (non-volatile) memory location, returning the
572 /// set of instructions that either define or clobber the value.
574 /// This method assumes the pointer has a "NonLocal" dependency within its
577 void MemoryDependenceAnalysis::
578 getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB,
579 SmallVectorImpl<NonLocalDepEntry> &Result) {
580 assert(isa<PointerType>(Pointer->getType()) &&
581 "Can't get pointer deps of a non-pointer!");
584 // We know that the pointer value is live into FromBB find the def/clobbers
585 // from presecessors.
586 const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
587 uint64_t PointeeSize = AA->getTypeStoreSize(EltTy);
589 // This is the set of blocks we've inspected, and the pointer we consider in
590 // each block. Because of critical edges, we currently bail out if querying
591 // a block with multiple different pointers. This can happen during PHI
593 DenseMap<BasicBlock*, Value*> Visited;
594 if (!getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB,
595 Result, Visited, true))
598 Result.push_back(std::make_pair(FromBB,
599 MemDepResult::getClobber(FromBB->begin())));
602 /// GetNonLocalInfoForBlock - Compute the memdep value for BB with
603 /// Pointer/PointeeSize using either cached information in Cache or by doing a
604 /// lookup (which may use dirty cache info if available). If we do a lookup,
605 /// add the result to the cache.
606 MemDepResult MemoryDependenceAnalysis::
607 GetNonLocalInfoForBlock(Value *Pointer, uint64_t PointeeSize,
608 bool isLoad, BasicBlock *BB,
609 NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
611 // Do a binary search to see if we already have an entry for this block in
612 // the cache set. If so, find it.
613 NonLocalDepInfo::iterator Entry =
614 std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
615 std::make_pair(BB, MemDepResult()));
616 if (Entry != Cache->begin() && prior(Entry)->first == BB)
619 MemDepResult *ExistingResult = 0;
620 if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
621 ExistingResult = &Entry->second;
623 // If we have a cached entry, and it is non-dirty, use it as the value for
625 if (ExistingResult && !ExistingResult->isDirty()) {
626 ++NumCacheNonLocalPtr;
627 return *ExistingResult;
630 // Otherwise, we have to scan for the value. If we have a dirty cache
631 // entry, start scanning from its position, otherwise we scan from the end
633 BasicBlock::iterator ScanPos = BB->end();
634 if (ExistingResult && ExistingResult->getInst()) {
635 assert(ExistingResult->getInst()->getParent() == BB &&
636 "Instruction invalidated?");
637 ++NumCacheDirtyNonLocalPtr;
638 ScanPos = ExistingResult->getInst();
640 // Eliminating the dirty entry from 'Cache', so update the reverse info.
641 ValueIsLoadPair CacheKey(Pointer, isLoad);
642 RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, CacheKey);
644 ++NumUncacheNonLocalPtr;
647 // Scan the block for the dependency.
648 MemDepResult Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad,
651 // If we had a dirty entry for the block, update it. Otherwise, just add
654 *ExistingResult = Dep;
656 Cache->push_back(std::make_pair(BB, Dep));
658 // If the block has a dependency (i.e. it isn't completely transparent to
659 // the value), remember the reverse association because we just added it
661 if (Dep.isNonLocal())
664 // Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
665 // update MemDep when we remove instructions.
666 Instruction *Inst = Dep.getInst();
667 assert(Inst && "Didn't depend on anything?");
668 ValueIsLoadPair CacheKey(Pointer, isLoad);
669 ReverseNonLocalPtrDeps[Inst].insert(CacheKey);
673 /// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain
674 /// number of elements in the array that are already properly ordered. This is
675 /// optimized for the case when only a few entries are added.
677 SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
678 unsigned NumSortedEntries) {
679 switch (Cache.size() - NumSortedEntries) {
681 // done, no new entries.
684 // Two new entries, insert the last one into place.
685 MemoryDependenceAnalysis::NonLocalDepEntry Val = Cache.back();
687 MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
688 std::upper_bound(Cache.begin(), Cache.end()-1, Val);
689 Cache.insert(Entry, Val);
693 // One new entry, Just insert the new value at the appropriate position.
694 if (Cache.size() != 1) {
695 MemoryDependenceAnalysis::NonLocalDepEntry Val = Cache.back();
697 MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
698 std::upper_bound(Cache.begin(), Cache.end(), Val);
699 Cache.insert(Entry, Val);
703 // Added many values, do a full scale sort.
704 std::sort(Cache.begin(), Cache.end());
709 /// isPHITranslatable - Return true if the specified computation is derived from
710 /// a PHI node in the current block and if it is simple enough for us to handle.
711 static bool isPHITranslatable(Instruction *Inst) {
712 if (isa<PHINode>(Inst))
715 // We can handle bitcast of a PHI, but the PHI needs to be in the same block
717 if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
718 Instruction *OpI = dyn_cast<Instruction>(BC->getOperand(0));
719 if (OpI == 0 || OpI->getParent() != Inst->getParent())
721 return isPHITranslatable(OpI);
724 // We can translate a GEP if all of its operands defined in this block are phi
726 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
727 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
728 Instruction *OpI = dyn_cast<Instruction>(GEP->getOperand(i));
729 if (OpI == 0 || OpI->getParent() != Inst->getParent())
732 if (!isPHITranslatable(OpI))
738 if (Inst->getOpcode() == Instruction::Add &&
739 isa<ConstantInt>(Inst->getOperand(1))) {
740 Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
741 if (OpI == 0 || OpI->getParent() != Inst->getParent())
743 return isPHITranslatable(OpI);
746 // cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
747 // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
748 // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
753 /// GetPHITranslatedValue - Given a computation that satisfied the
754 /// isPHITranslatable predicate, see if we can translate the computation into
755 /// the specified predecessor block. If so, return that value.
756 Value *MemoryDependenceAnalysis::
757 GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
758 const TargetData *TD) const {
759 // If the input value is not an instruction, or if it is not defined in CurBB,
760 // then we don't need to phi translate it.
761 Instruction *Inst = dyn_cast<Instruction>(InVal);
762 if (Inst == 0 || Inst->getParent() != CurBB)
765 if (PHINode *PN = dyn_cast<PHINode>(Inst))
766 return PN->getIncomingValueForBlock(Pred);
768 // Handle bitcast of PHI.
769 if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
770 // PHI translate the input operand.
771 Value *PHIIn = GetPHITranslatedValue(BC->getOperand(0), CurBB, Pred, TD);
772 if (PHIIn == 0) return 0;
774 // Constants are trivial to phi translate.
775 if (Constant *C = dyn_cast<Constant>(PHIIn))
776 return ConstantExpr::getBitCast(C, BC->getType());
778 // Otherwise we have to see if a bitcasted version of the incoming pointer
779 // is available. If so, we can use it, otherwise we have to fail.
780 for (Value::use_iterator UI = PHIIn->use_begin(), E = PHIIn->use_end();
782 if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI))
783 if (BCI->getType() == BC->getType())
789 // Handle getelementptr with at least one PHI translatable operand.
790 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
791 SmallVector<Value*, 8> GEPOps;
792 BasicBlock *CurBB = GEP->getParent();
793 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
794 Value *GEPOp = GEP->getOperand(i);
795 // No PHI translation is needed of operands whose values are live in to
796 // the predecessor block.
797 if (!isa<Instruction>(GEPOp) ||
798 cast<Instruction>(GEPOp)->getParent() != CurBB) {
799 GEPOps.push_back(GEPOp);
803 // If the operand is a phi node, do phi translation.
804 Value *InOp = GetPHITranslatedValue(GEPOp, CurBB, Pred, TD);
805 if (InOp == 0) return 0;
807 GEPOps.push_back(InOp);
810 // Simplify the GEP to handle 'gep x, 0' -> x etc.
811 if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD))
814 // Scan to see if we have this GEP available.
815 Value *APHIOp = GEPOps[0];
816 for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
818 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI))
819 if (GEPI->getType() == GEP->getType() &&
820 GEPI->getNumOperands() == GEPOps.size() &&
821 GEPI->getParent()->getParent() == CurBB->getParent()) {
822 bool Mismatch = false;
823 for (unsigned i = 0, e = GEPOps.size(); i != e; ++i)
824 if (GEPI->getOperand(i) != GEPOps[i]) {
835 // Handle add with a constant RHS.
836 if (Inst->getOpcode() == Instruction::Add &&
837 isa<ConstantInt>(Inst->getOperand(1))) {
838 // PHI translate the LHS.
840 Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
841 Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
842 bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
843 bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
845 if (OpI == 0 || OpI->getParent() != Inst->getParent())
846 LHS = Inst->getOperand(0);
848 LHS = GetPHITranslatedValue(Inst->getOperand(0), CurBB, Pred, TD);
853 // If the PHI translated LHS is an add of a constant, fold the immediates.
854 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
855 if (BOp->getOpcode() == Instruction::Add)
856 if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
857 LHS = BOp->getOperand(0);
858 RHS = ConstantExpr::getAdd(RHS, CI);
859 isNSW = isNUW = false;
862 // See if the add simplifies away.
863 if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, TD))
866 // Otherwise, see if we have this add available somewhere.
867 for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
869 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI))
870 if (BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
871 BO->getParent()->getParent() == CurBB->getParent())
881 /// GetAvailablePHITranslatePointer - Return the value computed by
882 /// PHITranslatePointer if it dominates PredBB, otherwise return null.
883 Value *MemoryDependenceAnalysis::
884 GetAvailablePHITranslatedValue(Value *V,
885 BasicBlock *CurBB, BasicBlock *PredBB,
886 const TargetData *TD,
887 const DominatorTree &DT) const {
888 // See if PHI translation succeeds.
889 V = GetPHITranslatedValue(V, CurBB, PredBB, TD);
890 if (V == 0) return 0;
892 // Make sure the value is live in the predecessor.
893 if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
894 if (!DT.dominates(Inst->getParent(), PredBB))
900 /// InsertPHITranslatedPointer - Insert a computation of the PHI translated
901 /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
902 /// block. All newly created instructions are added to the NewInsts list.
904 Value *MemoryDependenceAnalysis::
905 InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
906 BasicBlock *PredBB, const TargetData *TD,
907 const DominatorTree &DT,
908 SmallVectorImpl<Instruction*> &NewInsts) const {
909 // See if we have a version of this value already available and dominating
910 // PredBB. If so, there is no need to insert a new copy.
911 if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT))
914 // If we don't have an available version of this value, it must be an
916 Instruction *Inst = cast<Instruction>(InVal);
918 // Handle bitcast of PHI translatable value.
919 if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
920 Value *OpVal = InsertPHITranslatedPointer(BC->getOperand(0),
921 CurBB, PredBB, TD, DT, NewInsts);
922 if (OpVal == 0) return 0;
924 // Otherwise insert a bitcast at the end of PredBB.
925 BitCastInst *New = new BitCastInst(OpVal, InVal->getType(),
926 InVal->getName()+".phi.trans.insert",
927 PredBB->getTerminator());
928 NewInsts.push_back(New);
932 // Handle getelementptr with at least one PHI operand.
933 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
934 SmallVector<Value*, 8> GEPOps;
935 BasicBlock *CurBB = GEP->getParent();
936 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
937 Value *OpVal = InsertPHITranslatedPointer(GEP->getOperand(i),
938 CurBB, PredBB, TD, DT, NewInsts);
939 if (OpVal == 0) return 0;
940 GEPOps.push_back(OpVal);
943 GetElementPtrInst *Result =
944 GetElementPtrInst::Create(GEPOps[0], GEPOps.begin()+1, GEPOps.end(),
945 InVal->getName()+".phi.trans.insert",
946 PredBB->getTerminator());
947 Result->setIsInBounds(GEP->isInBounds());
948 NewInsts.push_back(Result);
953 // FIXME: This code works, but it is unclear that we actually want to insert
954 // a big chain of computation in order to make a value available in a block.
955 // This needs to be evaluated carefully to consider its cost trade offs.
957 // Handle add with a constant RHS.
958 if (Inst->getOpcode() == Instruction::Add &&
959 isa<ConstantInt>(Inst->getOperand(1))) {
960 // PHI translate the LHS.
961 Value *OpVal = InsertPHITranslatedPointer(Inst->getOperand(0),
962 CurBB, PredBB, TD, DT, NewInsts);
963 if (OpVal == 0) return 0;
965 BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1),
966 InVal->getName()+".phi.trans.insert",
967 PredBB->getTerminator());
968 Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap());
969 Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap());
970 NewInsts.push_back(Res);
978 /// getNonLocalPointerDepFromBB - Perform a dependency query based on
979 /// pointer/pointeesize starting at the end of StartBB. Add any clobber/def
980 /// results to the results vector and keep track of which blocks are visited in
983 /// This has special behavior for the first block queries (when SkipFirstBlock
984 /// is true). In this special case, it ignores the contents of the specified
985 /// block and starts returning dependence info for its predecessors.
987 /// This function returns false on success, or true to indicate that it could
988 /// not compute dependence information for some reason. This should be treated
989 /// as a clobber dependence on the first instruction in the predecessor block.
990 bool MemoryDependenceAnalysis::
991 getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
992 bool isLoad, BasicBlock *StartBB,
993 SmallVectorImpl<NonLocalDepEntry> &Result,
994 DenseMap<BasicBlock*, Value*> &Visited,
995 bool SkipFirstBlock) {
997 // Look up the cached info for Pointer.
998 ValueIsLoadPair CacheKey(Pointer, isLoad);
1000 std::pair<BBSkipFirstBlockPair, NonLocalDepInfo> *CacheInfo =
1001 &NonLocalPointerDeps[CacheKey];
1002 NonLocalDepInfo *Cache = &CacheInfo->second;
1004 // If we have valid cached information for exactly the block we are
1005 // investigating, just return it with no recomputation.
1006 if (CacheInfo->first == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
1007 // We have a fully cached result for this query then we can just return the
1008 // cached results and populate the visited set. However, we have to verify
1009 // that we don't already have conflicting results for these blocks. Check
1010 // to ensure that if a block in the results set is in the visited set that
1011 // it was for the same pointer query.
1012 if (!Visited.empty()) {
1013 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
1015 DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->first);
1016 if (VI == Visited.end() || VI->second == Pointer) continue;
1018 // We have a pointer mismatch in a block. Just return clobber, saying
1019 // that something was clobbered in this result. We could also do a
1020 // non-fully cached query, but there is little point in doing this.
1025 for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
1027 Visited.insert(std::make_pair(I->first, Pointer));
1028 if (!I->second.isNonLocal())
1029 Result.push_back(*I);
1031 ++NumCacheCompleteNonLocalPtr;
1035 // Otherwise, either this is a new block, a block with an invalid cache
1036 // pointer or one that we're about to invalidate by putting more info into it
1037 // than its valid cache info. If empty, the result will be valid cache info,
1038 // otherwise it isn't.
1040 CacheInfo->first = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
1042 CacheInfo->first = BBSkipFirstBlockPair();
1044 SmallVector<BasicBlock*, 32> Worklist;
1045 Worklist.push_back(StartBB);
1047 // Keep track of the entries that we know are sorted. Previously cached
1048 // entries will all be sorted. The entries we add we only sort on demand (we
1049 // don't insert every element into its sorted position). We know that we
1050 // won't get any reuse from currently inserted values, because we don't
1051 // revisit blocks after we insert info for them.
1052 unsigned NumSortedEntries = Cache->size();
1053 DEBUG(AssertSorted(*Cache));
1055 while (!Worklist.empty()) {
1056 BasicBlock *BB = Worklist.pop_back_val();
1058 // Skip the first block if we have it.
1059 if (!SkipFirstBlock) {
1060 // Analyze the dependency of *Pointer in FromBB. See if we already have
1062 assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
1064 // Get the dependency info for Pointer in BB. If we have cached
1065 // information, we will use it, otherwise we compute it.
1066 DEBUG(AssertSorted(*Cache, NumSortedEntries));
1067 MemDepResult Dep = GetNonLocalInfoForBlock(Pointer, PointeeSize, isLoad,
1068 BB, Cache, NumSortedEntries);
1070 // If we got a Def or Clobber, add this to the list of results.
1071 if (!Dep.isNonLocal()) {
1072 Result.push_back(NonLocalDepEntry(BB, Dep));
1077 // If 'Pointer' is an instruction defined in this block, then we need to do
1078 // phi translation to change it into a value live in the predecessor block.
1079 // If phi translation fails, then we can't continue dependence analysis.
1080 Instruction *PtrInst = dyn_cast<Instruction>(Pointer);
1081 bool NeedsPHITranslation = PtrInst && PtrInst->getParent() == BB;
1083 // If no PHI translation is needed, just add all the predecessors of this
1084 // block to scan them as well.
1085 if (!NeedsPHITranslation) {
1086 SkipFirstBlock = false;
1087 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
1088 // Verify that we haven't looked at this block yet.
1089 std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
1090 InsertRes = Visited.insert(std::make_pair(*PI, Pointer));
1091 if (InsertRes.second) {
1092 // First time we've looked at *PI.
1093 Worklist.push_back(*PI);
1097 // If we have seen this block before, but it was with a different
1098 // pointer then we have a phi translation failure and we have to treat
1099 // this as a clobber.
1100 if (InsertRes.first->second != Pointer)
1101 goto PredTranslationFailure;
1106 // If we do need to do phi translation, then there are a bunch of different
1107 // cases, because we have to find a Value* live in the predecessor block. We
1108 // know that PtrInst is defined in this block at least.
1110 // We may have added values to the cache list before this PHI translation.
1111 // If so, we haven't done anything to ensure that the cache remains sorted.
1112 // Sort it now (if needed) so that recursive invocations of
1113 // getNonLocalPointerDepFromBB and other routines that could reuse the cache
1114 // value will only see properly sorted cache arrays.
1115 if (Cache && NumSortedEntries != Cache->size()) {
1116 SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
1117 NumSortedEntries = Cache->size();
1120 // If this is a computation derived from a PHI node, use the suitably
1121 // translated incoming values for each pred as the phi translated version.
1122 if (!isPHITranslatable(PtrInst))
1123 goto PredTranslationFailure;
1127 for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
1128 BasicBlock *Pred = *PI;
1129 // Get the PHI translated pointer in this predecessor. This can fail and
1130 // return null if not translatable.
1131 Value *PredPtr = GetPHITranslatedValue(PtrInst, BB, Pred, TD);
1133 // Check to see if we have already visited this pred block with another
1134 // pointer. If so, we can't do this lookup. This failure can occur
1135 // with PHI translation when a critical edge exists and the PHI node in
1136 // the successor translates to a pointer value different than the
1137 // pointer the block was first analyzed with.
1138 std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
1139 InsertRes = Visited.insert(std::make_pair(Pred, PredPtr));
1141 if (!InsertRes.second) {
1142 // If the predecessor was visited with PredPtr, then we already did
1143 // the analysis and can ignore it.
1144 if (InsertRes.first->second == PredPtr)
1147 // Otherwise, the block was previously analyzed with a different
1148 // pointer. We can't represent the result of this case, so we just
1149 // treat this as a phi translation failure.
1150 goto PredTranslationFailure;
1153 // If PHI translation was unable to find an available pointer in this
1154 // predecessor, then we have to assume that the pointer is clobbered in
1155 // that predecessor. We can still do PRE of the load, which would insert
1156 // a computation of the pointer in this predecessor.
1158 // Add the entry to the Result list.
1159 NonLocalDepEntry Entry(Pred,
1160 MemDepResult::getClobber(Pred->getTerminator()));
1161 Result.push_back(Entry);
1163 // Add it to the cache for this CacheKey so that subsequent queries get
1165 Cache = &NonLocalPointerDeps[CacheKey].second;
1166 MemoryDependenceAnalysis::NonLocalDepInfo::iterator It =
1167 std::upper_bound(Cache->begin(), Cache->end(), Entry);
1169 if (It != Cache->begin() && prior(It)->first == Pred)
1172 if (It == Cache->end() || It->first != Pred) {
1173 Cache->insert(It, Entry);
1174 // Add it to the reverse map.
1175 ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
1176 } else if (!It->second.isDirty()) {
1178 } else if (It->second.getInst() == Pred->getTerminator()) {
1179 // Same instruction, clear the dirty marker.
1180 It->second = Entry.second;
1181 } else if (It->second.getInst() == 0) {
1182 // Dirty, with no instruction, just add this.
1183 It->second = Entry.second;
1184 ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
1186 // Otherwise, dirty with a different instruction.
1187 RemoveFromReverseMap(ReverseNonLocalPtrDeps, It->second.getInst(),
1189 It->second = Entry.second;
1190 ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
1196 // FIXME: it is entirely possible that PHI translating will end up with
1197 // the same value. Consider PHI translating something like:
1198 // X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need*
1199 // to recurse here, pedantically speaking.
1201 // If we have a problem phi translating, fall through to the code below
1202 // to handle the failure condition.
1203 if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred,
1205 goto PredTranslationFailure;
1208 // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
1209 CacheInfo = &NonLocalPointerDeps[CacheKey];
1210 Cache = &CacheInfo->second;
1211 NumSortedEntries = Cache->size();
1213 // Since we did phi translation, the "Cache" set won't contain all of the
1214 // results for the query. This is ok (we can still use it to accelerate
1215 // specific block queries) but we can't do the fastpath "return all
1216 // results from the set" Clear out the indicator for this.
1217 CacheInfo->first = BBSkipFirstBlockPair();
1218 SkipFirstBlock = false;
1221 PredTranslationFailure:
1224 // Refresh the CacheInfo/Cache pointer if it got invalidated.
1225 CacheInfo = &NonLocalPointerDeps[CacheKey];
1226 Cache = &CacheInfo->second;
1227 NumSortedEntries = Cache->size();
1230 // Since we did phi translation, the "Cache" set won't contain all of the
1231 // results for the query. This is ok (we can still use it to accelerate
1232 // specific block queries) but we can't do the fastpath "return all
1233 // results from the set" Clear out the indicator for this.
1234 CacheInfo->first = BBSkipFirstBlockPair();
1236 // If *nothing* works, mark the pointer as being clobbered by the first
1237 // instruction in this block.
1239 // If this is the magic first block, return this as a clobber of the whole
1240 // incoming value. Since we can't phi translate to one of the predecessors,
1241 // we have to bail out.
1245 for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) {
1246 assert(I != Cache->rend() && "Didn't find current block??");
1250 assert(I->second.isNonLocal() &&
1251 "Should only be here with transparent block");
1252 I->second = MemDepResult::getClobber(BB->begin());
1253 ReverseNonLocalPtrDeps[BB->begin()].insert(CacheKey);
1254 Result.push_back(*I);
1259 // Okay, we're done now. If we added new values to the cache, re-sort it.
1260 SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
1261 DEBUG(AssertSorted(*Cache));
1265 /// RemoveCachedNonLocalPointerDependencies - If P exists in
1266 /// CachedNonLocalPointerInfo, remove it.
1267 void MemoryDependenceAnalysis::
1268 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
1269 CachedNonLocalPointerInfo::iterator It =
1270 NonLocalPointerDeps.find(P);
1271 if (It == NonLocalPointerDeps.end()) return;
1273 // Remove all of the entries in the BB->val map. This involves removing
1274 // instructions from the reverse map.
1275 NonLocalDepInfo &PInfo = It->second.second;
1277 for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
1278 Instruction *Target = PInfo[i].second.getInst();
1279 if (Target == 0) continue; // Ignore non-local dep results.
1280 assert(Target->getParent() == PInfo[i].first);
1282 // Eliminating the dirty entry from 'Cache', so update the reverse info.
1283 RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P);
1286 // Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
1287 NonLocalPointerDeps.erase(It);
1291 /// invalidateCachedPointerInfo - This method is used to invalidate cached
1292 /// information about the specified pointer, because it may be too
1293 /// conservative in memdep. This is an optional call that can be used when
1294 /// the client detects an equivalence between the pointer and some other
1295 /// value and replaces the other value with ptr. This can make Ptr available
1296 /// in more places that cached info does not necessarily keep.
1297 void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
1298 // If Ptr isn't really a pointer, just ignore it.
1299 if (!isa<PointerType>(Ptr->getType())) return;
1300 // Flush store info for the pointer.
1301 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
1302 // Flush load info for the pointer.
1303 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
1306 /// removeInstruction - Remove an instruction from the dependence analysis,
1307 /// updating the dependence of instructions that previously depended on it.
1308 /// This method attempts to keep the cache coherent using the reverse map.
1309 void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
1310 // Walk through the Non-local dependencies, removing this one as the value
1311 // for any cached queries.
1312 NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
1313 if (NLDI != NonLocalDeps.end()) {
1314 NonLocalDepInfo &BlockMap = NLDI->second.first;
1315 for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
1317 if (Instruction *Inst = DI->second.getInst())
1318 RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
1319 NonLocalDeps.erase(NLDI);
1322 // If we have a cached local dependence query for this instruction, remove it.
1324 LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
1325 if (LocalDepEntry != LocalDeps.end()) {
1326 // Remove us from DepInst's reverse set now that the local dep info is gone.
1327 if (Instruction *Inst = LocalDepEntry->second.getInst())
1328 RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
1330 // Remove this local dependency info.
1331 LocalDeps.erase(LocalDepEntry);
1334 // If we have any cached pointer dependencies on this instruction, remove
1335 // them. If the instruction has non-pointer type, then it can't be a pointer
1338 // Remove it from both the load info and the store info. The instruction
1339 // can't be in either of these maps if it is non-pointer.
1340 if (isa<PointerType>(RemInst->getType())) {
1341 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
1342 RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
1345 // Loop over all of the things that depend on the instruction we're removing.
1347 SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
1349 // If we find RemInst as a clobber or Def in any of the maps for other values,
1350 // we need to replace its entry with a dirty version of the instruction after
1351 // it. If RemInst is a terminator, we use a null dirty value.
1353 // Using a dirty version of the instruction after RemInst saves having to scan
1354 // the entire block to get to this point.
1355 MemDepResult NewDirtyVal;
1356 if (!RemInst->isTerminator())
1357 NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
1359 ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
1360 if (ReverseDepIt != ReverseLocalDeps.end()) {
1361 SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
1362 // RemInst can't be the terminator if it has local stuff depending on it.
1363 assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
1364 "Nothing can locally depend on a terminator");
1366 for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
1367 E = ReverseDeps.end(); I != E; ++I) {
1368 Instruction *InstDependingOnRemInst = *I;
1369 assert(InstDependingOnRemInst != RemInst &&
1370 "Already removed our local dep info");
1372 LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
1374 // Make sure to remember that new things depend on NewDepInst.
1375 assert(NewDirtyVal.getInst() && "There is no way something else can have "
1376 "a local dep on this if it is a terminator!");
1377 ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(),
1378 InstDependingOnRemInst));
1381 ReverseLocalDeps.erase(ReverseDepIt);
1383 // Add new reverse deps after scanning the set, to avoid invalidating the
1384 // 'ReverseDeps' reference.
1385 while (!ReverseDepsToAdd.empty()) {
1386 ReverseLocalDeps[ReverseDepsToAdd.back().first]
1387 .insert(ReverseDepsToAdd.back().second);
1388 ReverseDepsToAdd.pop_back();
1392 ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
1393 if (ReverseDepIt != ReverseNonLocalDeps.end()) {
1394 SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
1395 for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
1397 assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
1399 PerInstNLInfo &INLD = NonLocalDeps[*I];
1400 // The information is now dirty!
1403 for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
1404 DE = INLD.first.end(); DI != DE; ++DI) {
1405 if (DI->second.getInst() != RemInst) continue;
1407 // Convert to a dirty entry for the subsequent instruction.
1408 DI->second = NewDirtyVal;
1410 if (Instruction *NextI = NewDirtyVal.getInst())
1411 ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
1415 ReverseNonLocalDeps.erase(ReverseDepIt);
1417 // Add new reverse deps after scanning the set, to avoid invalidating 'Set'
1418 while (!ReverseDepsToAdd.empty()) {
1419 ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
1420 .insert(ReverseDepsToAdd.back().second);
1421 ReverseDepsToAdd.pop_back();
1425 // If the instruction is in ReverseNonLocalPtrDeps then it appears as a
1426 // value in the NonLocalPointerDeps info.
1427 ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
1428 ReverseNonLocalPtrDeps.find(RemInst);
1429 if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
1430 SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second;
1431 SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
1433 for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(),
1434 E = Set.end(); I != E; ++I) {
1435 ValueIsLoadPair P = *I;
1436 assert(P.getPointer() != RemInst &&
1437 "Already removed NonLocalPointerDeps info for RemInst");
1439 NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].second;
1441 // The cache is not valid for any specific block anymore.
1442 NonLocalPointerDeps[P].first = BBSkipFirstBlockPair();
1444 // Update any entries for RemInst to use the instruction after it.
1445 for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
1447 if (DI->second.getInst() != RemInst) continue;
1449 // Convert to a dirty entry for the subsequent instruction.
1450 DI->second = NewDirtyVal;
1452 if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
1453 ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
1456 // Re-sort the NonLocalDepInfo. Changing the dirty entry to its
1457 // subsequent value may invalidate the sortedness.
1458 std::sort(NLPDI.begin(), NLPDI.end());
1461 ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
1463 while (!ReversePtrDepsToAdd.empty()) {
1464 ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
1465 .insert(ReversePtrDepsToAdd.back().second);
1466 ReversePtrDepsToAdd.pop_back();
1471 assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
1472 AA->deleteValue(RemInst);
1473 DEBUG(verifyRemoved(RemInst));
1475 /// verifyRemoved - Verify that the specified instruction does not occur
1476 /// in our internal data structures.
1477 void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
1478 for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
1479 E = LocalDeps.end(); I != E; ++I) {
1480 assert(I->first != D && "Inst occurs in data structures");
1481 assert(I->second.getInst() != D &&
1482 "Inst occurs in data structures");
1485 for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
1486 E = NonLocalPointerDeps.end(); I != E; ++I) {
1487 assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
1488 const NonLocalDepInfo &Val = I->second.second;
1489 for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
1491 assert(II->second.getInst() != D && "Inst occurs as NLPD value");
1494 for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
1495 E = NonLocalDeps.end(); I != E; ++I) {
1496 assert(I->first != D && "Inst occurs in data structures");
1497 const PerInstNLInfo &INLD = I->second;
1498 for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
1499 EE = INLD.first.end(); II != EE; ++II)
1500 assert(II->second.getInst() != D && "Inst occurs in data structures");
1503 for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
1504 E = ReverseLocalDeps.end(); I != E; ++I) {
1505 assert(I->first != D && "Inst occurs in data structures");
1506 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
1507 EE = I->second.end(); II != EE; ++II)
1508 assert(*II != D && "Inst occurs in data structures");
1511 for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
1512 E = ReverseNonLocalDeps.end();
1514 assert(I->first != D && "Inst occurs in data structures");
1515 for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
1516 EE = I->second.end(); II != EE; ++II)
1517 assert(*II != D && "Inst occurs in data structures");
1520 for (ReverseNonLocalPtrDepTy::const_iterator
1521 I = ReverseNonLocalPtrDeps.begin(),
1522 E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
1523 assert(I->first != D && "Inst occurs in rev NLPD map");
1525 for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(),
1526 E = I->second.end(); II != E; ++II)
1527 assert(*II != ValueIsLoadPair(D, false) &&
1528 *II != ValueIsLoadPair(D, true) &&
1529 "Inst occurs in ReverseNonLocalPtrDeps map");