1 //===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the AliasSetTracker and AliasSet classes.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/AliasSetTracker.h"
15 #include "llvm/Analysis/AliasAnalysis.h"
16 #include "llvm/Instructions.h"
17 #include "llvm/Pass.h"
18 #include "llvm/Type.h"
19 #include "llvm/Target/TargetData.h"
20 #include "llvm/Assembly/Writer.h"
21 #include "llvm/Support/Compiler.h"
22 #include "llvm/Support/InstIterator.h"
23 #include "llvm/Support/Streams.h"
26 /// mergeSetIn - Merge the specified alias set into this alias set.
28 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
29 assert(!AS.Forward && "Alias set is already forwarding!");
30 assert(!Forward && "This set is a forwarding set!!");
32 // Update the alias and access types of this set...
33 AccessTy |= AS.AccessTy;
34 AliasTy |= AS.AliasTy;
36 if (AliasTy == MustAlias) {
37 // Check that these two merged sets really are must aliases. Since both
38 // used to be must-alias sets, we can just check any pointer from each set
40 AliasAnalysis &AA = AST.getAliasAnalysis();
41 HashNodePair *L = getSomePointer();
42 HashNodePair *R = AS.getSomePointer();
44 // If the pointers are not a must-alias pair, this set becomes a may alias.
45 if (AA.alias(L->first, L->second.getSize(), R->first, R->second.getSize())
46 != AliasAnalysis::MustAlias)
50 if (CallSites.empty()) { // Merge call sites...
51 if (!AS.CallSites.empty())
52 std::swap(CallSites, AS.CallSites);
53 } else if (!AS.CallSites.empty()) {
54 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
58 AS.Forward = this; // Forward across AS now...
59 addRef(); // AS is now pointing to us...
61 // Merge the list of constituent pointers...
63 *PtrListEnd = AS.PtrList;
64 AS.PtrList->second.setPrevInList(PtrListEnd);
65 PtrListEnd = AS.PtrListEnd;
68 AS.PtrListEnd = &AS.PtrList;
69 assert(*AS.PtrListEnd == 0 && "End of list is not null?");
73 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
74 if (AliasSet *Fwd = AS->Forward) {
81 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
82 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
83 AST.removeAliasSet(this);
86 void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry,
87 unsigned Size, bool KnownMustAlias) {
88 assert(!Entry.second.hasAliasSet() && "Entry already in set!");
90 // Check to see if we have to downgrade to _may_ alias.
91 if (isMustAlias() && !KnownMustAlias)
92 if (HashNodePair *P = getSomePointer()) {
93 AliasAnalysis &AA = AST.getAliasAnalysis();
94 AliasAnalysis::AliasResult Result =
95 AA.alias(P->first, P->second.getSize(), Entry.first, Size);
96 if (Result == AliasAnalysis::MayAlias)
98 else // First entry of must alias must have maximum size!
99 P->second.updateSize(Size);
100 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
103 Entry.second.setAliasSet(this);
104 Entry.second.updateSize(Size);
106 // Add it to the end of the list...
107 assert(*PtrListEnd == 0 && "End of list is not null?");
108 *PtrListEnd = &Entry;
109 PtrListEnd = Entry.second.setPrevInList(PtrListEnd);
110 assert(*PtrListEnd == 0 && "End of list is not null?");
111 addRef(); // Entry points to alias set...
114 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
115 CallSites.push_back(CS);
117 if (Function *F = CS.getCalledFunction()) {
118 AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(F, CS);
119 if (Behavior == AliasAnalysis::DoesNotAccessMemory)
121 else if (Behavior == AliasAnalysis::OnlyReadsMemory) {
128 // FIXME: This should use mod/ref information to make this not suck so bad
133 /// aliasesPointer - Return true if the specified pointer "may" (or must)
134 /// alias one of the members in the set.
136 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
137 AliasAnalysis &AA) const {
138 if (AliasTy == MustAlias) {
139 assert(CallSites.empty() && "Illegal must alias set!");
141 // If this is a set of MustAliases, only check to see if the pointer aliases
142 // SOME value in the set...
143 HashNodePair *SomePtr = getSomePointer();
144 assert(SomePtr && "Empty must-alias set??");
145 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
148 // If this is a may-alias set, we have to check all of the pointers in the set
149 // to be sure it doesn't alias the set...
150 for (iterator I = begin(), E = end(); I != E; ++I)
151 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
154 // Check the call sites list and invoke list...
155 if (!CallSites.empty()) {
156 if (AA.hasNoModRefInfoForCalls())
159 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
160 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
161 != AliasAnalysis::NoModRef)
168 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
169 if (Function *F = CS.getCalledFunction())
170 if (AA.doesNotAccessMemory(F))
173 if (AA.hasNoModRefInfoForCalls())
176 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
177 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
178 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
181 for (iterator I = begin(), E = end(); I != E; ++I)
182 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
183 AliasAnalysis::NoModRef)
190 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
191 /// instruction referring to the pointer into. If there are multiple alias sets
192 /// that may alias the pointer, merge them together and return the unified set.
194 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
196 AliasSet *FoundSet = 0;
197 for (iterator I = begin(), E = end(); I != E; ++I)
198 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
199 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
200 FoundSet = I; // Remember it.
201 } else { // Otherwise, we must merge the sets.
202 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
209 /// containsPointer - Return true if the specified location is represented by
210 /// this alias set, false otherwise. This does not modify the AST object or
212 bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
213 for (const_iterator I = begin(), E = end(); I != E; ++I)
214 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
221 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
222 AliasSet *FoundSet = 0;
223 for (iterator I = begin(), E = end(); I != E; ++I)
224 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
225 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
226 FoundSet = I; // Remember it.
227 } else if (!I->Forward) { // Otherwise, we must merge the sets.
228 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
238 /// getAliasSetForPointer - Return the alias set that the specified pointer
240 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
242 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
244 // Check to see if the pointer is already known...
245 if (Entry.second.hasAliasSet()) {
246 Entry.second.updateSize(Size);
248 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
249 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
250 // Add it to the alias set it aliases...
251 AS->addPointer(*this, Entry, Size);
254 if (New) *New = true;
255 // Otherwise create a new alias set to hold the loaded pointer...
256 AliasSets.push_back(new AliasSet());
257 AliasSets.back().addPointer(*this, Entry, Size);
258 return AliasSets.back();
262 bool AliasSetTracker::add(Value *Ptr, unsigned Size) {
264 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr);
269 bool AliasSetTracker::add(LoadInst *LI) {
271 AliasSet &AS = addPointer(LI->getOperand(0),
272 AA.getTargetData().getTypeSize(LI->getType()),
273 AliasSet::Refs, NewPtr);
274 if (LI->isVolatile()) AS.setVolatile();
278 bool AliasSetTracker::add(StoreInst *SI) {
280 Value *Val = SI->getOperand(0);
281 AliasSet &AS = addPointer(SI->getOperand(1),
282 AA.getTargetData().getTypeSize(Val->getType()),
283 AliasSet::Mods, NewPtr);
284 if (SI->isVolatile()) AS.setVolatile();
288 bool AliasSetTracker::add(FreeInst *FI) {
290 AliasSet &AS = addPointer(FI->getOperand(0), ~0,
291 AliasSet::Mods, NewPtr);
293 // Free operations are volatile ops (cannot be moved).
299 bool AliasSetTracker::add(CallSite CS) {
300 if (Function *F = CS.getCalledFunction())
301 if (AA.doesNotAccessMemory(F))
302 return true; // doesn't alias anything
304 AliasSet *AS = findAliasSetForCallSite(CS);
306 AliasSets.push_back(new AliasSet());
307 AS = &AliasSets.back();
308 AS->addCallSite(CS, AA);
311 AS->addCallSite(CS, AA);
316 bool AliasSetTracker::add(Instruction *I) {
317 // Dispatch to one of the other add methods...
318 if (LoadInst *LI = dyn_cast<LoadInst>(I))
320 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
322 else if (CallInst *CI = dyn_cast<CallInst>(I))
324 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
326 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
331 void AliasSetTracker::add(BasicBlock &BB) {
332 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
336 void AliasSetTracker::add(const AliasSetTracker &AST) {
337 assert(&AA == &AST.AA &&
338 "Merging AliasSetTracker objects with different Alias Analyses!");
340 // Loop over all of the alias sets in AST, adding the pointers contained
341 // therein into the current alias sets. This can cause alias sets to be
342 // merged together in the current AST.
343 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
344 if (!I->Forward) { // Ignore forwarding alias sets
345 AliasSet &AS = const_cast<AliasSet&>(*I);
347 // If there are any call sites in the alias set, add them to this AST.
348 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
349 add(AS.CallSites[i]);
351 // Loop over all of the pointers in this alias set...
352 AliasSet::iterator I = AS.begin(), E = AS.end();
355 addPointer(I.getPointer(), I.getSize(),
356 (AliasSet::AccessType)AS.AccessTy, X);
360 /// remove - Remove the specified (potentially non-empty) alias set from the
362 void AliasSetTracker::remove(AliasSet &AS) {
363 // Drop all call sites.
364 AS.CallSites.clear();
366 // Clear the alias set.
367 unsigned NumRefs = 0;
368 while (!AS.empty()) {
369 AliasSet::HashNodePair *P = AS.PtrList;
371 // Unlink from the list of values.
372 P->second.removeFromList();
374 // Remember how many references need to be dropped.
377 // Finally, remove the entry.
378 Value *Remove = P->first; // Take a copy because it is invalid to pass
379 PointerMap.erase(Remove); // a reference to the data being erased.
382 // Stop using the alias set, removing it.
383 AS.RefCount -= NumRefs;
384 if (AS.RefCount == 0)
385 AS.removeFromTracker(*this);
388 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {
389 AliasSet *AS = findAliasSetForPointer(Ptr, Size);
390 if (!AS) return false;
395 bool AliasSetTracker::remove(LoadInst *LI) {
396 unsigned Size = AA.getTargetData().getTypeSize(LI->getType());
397 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
398 if (!AS) return false;
403 bool AliasSetTracker::remove(StoreInst *SI) {
404 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType());
405 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
406 if (!AS) return false;
411 bool AliasSetTracker::remove(FreeInst *FI) {
412 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0);
413 if (!AS) return false;
418 bool AliasSetTracker::remove(CallSite CS) {
419 if (Function *F = CS.getCalledFunction())
420 if (AA.doesNotAccessMemory(F))
421 return false; // doesn't alias anything
423 AliasSet *AS = findAliasSetForCallSite(CS);
424 if (!AS) return false;
429 bool AliasSetTracker::remove(Instruction *I) {
430 // Dispatch to one of the other remove methods...
431 if (LoadInst *LI = dyn_cast<LoadInst>(I))
433 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
435 else if (CallInst *CI = dyn_cast<CallInst>(I))
437 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
443 // deleteValue method - This method is used to remove a pointer value from the
444 // AliasSetTracker entirely. It should be used when an instruction is deleted
445 // from the program to update the AST. If you don't use this, you would have
446 // dangling pointers to deleted instructions.
448 void AliasSetTracker::deleteValue(Value *PtrVal) {
449 // Notify the alias analysis implementation that this value is gone.
450 AA.deleteValue(PtrVal);
452 // If this is a call instruction, remove the callsite from the appropriate
454 CallSite CS = CallSite::get(PtrVal);
455 if (CS.getInstruction()) {
456 Function *F = CS.getCalledFunction();
457 if (!F || !AA.doesNotAccessMemory(F)) {
458 if (AliasSet *AS = findAliasSetForCallSite(CS))
459 AS->removeCallSite(CS);
463 // First, look up the PointerRec for this pointer.
464 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
465 if (I == PointerMap.end()) return; // Noop
467 // If we found one, remove the pointer from the alias set it is in.
468 AliasSet::HashNodePair &PtrValEnt = *I;
469 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
471 // Unlink from the list of values...
472 PtrValEnt.second.removeFromList();
473 // Stop using the alias set
478 // copyValue - This method should be used whenever a preexisting value in the
479 // program is copied or cloned, introducing a new value. Note that it is ok for
480 // clients that use this method to introduce the same value multiple times: if
481 // the tracker already knows about a value, it will ignore the request.
483 void AliasSetTracker::copyValue(Value *From, Value *To) {
484 // Notify the alias analysis implementation that this value is copied.
485 AA.copyValue(From, To);
487 // First, look up the PointerRec for this pointer.
488 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From);
489 if (I == PointerMap.end() || !I->second.hasAliasSet())
492 AliasSet::HashNodePair &Entry = getEntryFor(To);
493 if (Entry.second.hasAliasSet()) return; // Already in the tracker!
495 // Add it to the alias set it aliases...
496 AliasSet *AS = I->second.getAliasSet(*this);
497 AS->addPointer(*this, Entry, I->second.getSize(), true);
502 //===----------------------------------------------------------------------===//
503 // AliasSet/AliasSetTracker Printing Support
504 //===----------------------------------------------------------------------===//
506 void AliasSet::print(std::ostream &OS) const {
507 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
508 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
510 case NoModRef: OS << "No access "; break;
511 case Refs : OS << "Ref "; break;
512 case Mods : OS << "Mod "; break;
513 case ModRef : OS << "Mod/Ref "; break;
514 default: assert(0 && "Bad value for AccessTy!");
516 if (isVolatile()) OS << "[volatile] ";
518 OS << " forwarding to " << (void*)Forward;
521 if (begin() != end()) {
523 for (iterator I = begin(), E = end(); I != E; ++I) {
524 if (I != begin()) OS << ", ";
525 WriteAsOperand(OS << "(", I.getPointer());
526 OS << ", " << I.getSize() << ")";
529 if (!CallSites.empty()) {
530 OS << "\n " << CallSites.size() << " Call Sites: ";
531 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
533 WriteAsOperand(OS, CallSites[i].getCalledValue());
539 void AliasSetTracker::print(std::ostream &OS) const {
540 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
541 << PointerMap.size() << " pointer values.\n";
542 for (const_iterator I = begin(), E = end(); I != E; ++I)
547 void AliasSet::dump() const { print (cerr); }
548 void AliasSetTracker::dump() const { print(cerr); }
550 //===----------------------------------------------------------------------===//
551 // AliasSetPrinter Pass
552 //===----------------------------------------------------------------------===//
555 class VISIBILITY_HIDDEN AliasSetPrinter : public FunctionPass {
556 AliasSetTracker *Tracker;
558 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
559 AU.setPreservesAll();
560 AU.addRequired<AliasAnalysis>();
563 virtual bool runOnFunction(Function &F) {
564 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
566 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
568 Tracker->print(cerr);
573 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer");