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/iMemory.h"
17 #include "llvm/iOther.h"
18 #include "llvm/iTerminators.h"
19 #include "llvm/Pass.h"
20 #include "llvm/Target/TargetData.h"
21 #include "llvm/Assembly/Writer.h"
22 #include "llvm/Support/InstIterator.h"
26 /// mergeSetIn - Merge the specified alias set into this alias set...
28 void AliasSet::mergeSetIn(AliasSet &AS) {
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 (CallSites.empty()) { // Merge call sites...
37 if (!AS.CallSites.empty())
38 std::swap(CallSites, AS.CallSites);
39 } else if (!AS.CallSites.empty()) {
40 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
44 // FIXME: If AS's refcount is zero, nuke it now...
45 assert(RefCount != 0);
47 AS.Forward = this; // Forward across AS now...
48 addRef(); // AS is now pointing to us...
50 // Merge the list of constituent pointers...
52 *PtrListEnd = AS.PtrList;
53 AS.PtrList->second.setPrevInList(PtrListEnd);
54 PtrListEnd = AS.PtrListEnd;
57 AS.PtrListEnd = &AS.PtrList;
61 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
62 if (AliasSet *Fwd = AS->Forward) {
69 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
70 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
71 AST.removeAliasSet(this);
74 void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry,
76 assert(!Entry.second.hasAliasSet() && "Entry already in set!");
78 AliasAnalysis &AA = AST.getAliasAnalysis();
80 if (isMustAlias()) // Check to see if we have to downgrade to _may_ alias
81 if (HashNodePair *P = getSomePointer()) {
82 AliasAnalysis::AliasResult Result =
83 AA.alias(P->first, P->second.getSize(), Entry.first, Size);
84 if (Result == AliasAnalysis::MayAlias)
86 else // First entry of must alias must have maximum size!
87 P->second.updateSize(Size);
88 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
91 Entry.second.setAliasSet(this);
92 Entry.second.updateSize(Size);
94 // Add it to the end of the list...
95 assert(*PtrListEnd == 0 && "End of list is not null?");
97 PtrListEnd = Entry.second.setPrevInList(PtrListEnd);
98 addRef(); // Entry points to alias set...
101 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
102 CallSites.push_back(CS);
104 if (Function *F = CS.getCalledFunction()) {
105 if (AA.doesNotAccessMemory(F))
107 else if (AA.onlyReadsMemory(F)) {
114 // FIXME: This should use mod/ref information to make this not suck so bad
119 /// aliasesPointer - Return true if the specified pointer "may" (or must)
120 /// alias one of the members in the set.
122 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
123 AliasAnalysis &AA) const {
124 if (AliasTy == MustAlias) {
125 assert(CallSites.empty() && "Illegal must alias set!");
127 // If this is a set of MustAliases, only check to see if the pointer aliases
128 // SOME value in the set...
129 HashNodePair *SomePtr = getSomePointer();
130 assert(SomePtr && "Empty must-alias set??");
131 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
134 // If this is a may-alias set, we have to check all of the pointers in the set
135 // to be sure it doesn't alias the set...
136 for (iterator I = begin(), E = end(); I != E; ++I)
137 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
140 // Check the call sites list and invoke list...
141 if (!CallSites.empty())
142 // FIXME: this is pessimistic!
148 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
149 // FIXME: Use mod/ref information to prune this better!
150 if (Function *F = CS.getCalledFunction())
151 if (AA.doesNotAccessMemory(F))
158 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
159 /// instruction referring to the pointer into. If there are multiple alias sets
160 /// that may alias the pointer, merge them together and return the unified set.
162 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
164 AliasSet *FoundSet = 0;
165 for (iterator I = begin(), E = end(); I != E; ++I)
166 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
167 if (FoundSet == 0) { // If this is the first alias set ptr can go into...
168 FoundSet = I; // Remember it.
169 } else { // Otherwise, we must merge the sets...
170 FoundSet->mergeSetIn(*I); // Merge in contents...
177 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
178 AliasSet *FoundSet = 0;
179 for (iterator I = begin(), E = end(); I != E; ++I)
180 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
181 if (FoundSet == 0) { // If this is the first alias set ptr can go into...
182 FoundSet = I; // Remember it.
183 } else if (!I->Forward) { // Otherwise, we must merge the sets...
184 FoundSet->mergeSetIn(*I); // Merge in contents...
194 /// getAliasSetForPointer - Return the alias set that the specified pointer
196 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
198 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
200 // Check to see if the pointer is already known...
201 if (Entry.second.hasAliasSet() && Size <= Entry.second.getSize()) {
203 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
204 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
205 // Add it to the alias set it aliases...
206 AS->addPointer(*this, Entry, Size);
209 if (New) *New = true;
210 // Otherwise create a new alias set to hold the loaded pointer...
211 AliasSets.push_back(new AliasSet());
212 AliasSets.back().addPointer(*this, Entry, Size);
213 return AliasSets.back();
217 bool AliasSetTracker::add(LoadInst *LI) {
219 AliasSet &AS = addPointer(LI->getOperand(0),
220 AA.getTargetData().getTypeSize(LI->getType()),
221 AliasSet::Refs, NewPtr);
222 if (LI->isVolatile()) AS.setVolatile();
226 bool AliasSetTracker::add(StoreInst *SI) {
228 Value *Val = SI->getOperand(0);
229 AliasSet &AS = addPointer(SI->getOperand(1),
230 AA.getTargetData().getTypeSize(Val->getType()),
231 AliasSet::Mods, NewPtr);
232 if (SI->isVolatile()) AS.setVolatile();
237 bool AliasSetTracker::add(CallSite CS) {
239 if (Function *F = CS.getCalledFunction())
240 if (AA.doesNotAccessMemory(F))
241 return true; // doesn't alias anything
243 AliasSet *AS = findAliasSetForCallSite(CS);
245 AliasSets.push_back(new AliasSet());
246 AS = &AliasSets.back();
247 AS->addCallSite(CS, AA);
250 AS->addCallSite(CS, AA);
255 bool AliasSetTracker::add(Instruction *I) {
256 // Dispatch to one of the other add methods...
257 if (LoadInst *LI = dyn_cast<LoadInst>(I))
259 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
261 else if (CallInst *CI = dyn_cast<CallInst>(I))
263 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
268 void AliasSetTracker::add(BasicBlock &BB) {
269 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
273 void AliasSetTracker::add(const AliasSetTracker &AST) {
274 assert(&AA == &AST.AA &&
275 "Merging AliasSetTracker objects with different Alias Analyses!");
277 // Loop over all of the alias sets in AST, adding the pointers contained
278 // therein into the current alias sets. This can cause alias sets to be
279 // merged together in the current AST.
280 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
281 if (!I->Forward) { // Ignore forwarding alias sets
282 AliasSet &AS = const_cast<AliasSet&>(*I);
284 // If there are any call sites in the alias set, add them to this AST.
285 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
286 add(AS.CallSites[i]);
288 // Loop over all of the pointers in this alias set...
289 AliasSet::iterator I = AS.begin(), E = AS.end();
292 addPointer(I.getPointer(), I.getSize(),
293 (AliasSet::AccessType)AS.AccessTy, X);
297 /// remove - Remove the specified (potentially non-empty) alias set from the
299 void AliasSetTracker::remove(AliasSet &AS) {
302 AliasSet::iterator I = AS.begin();
303 Value *Ptr = I.getPointer(); ++I;
305 // deleteValue will delete the set automatically when the last pointer
306 // reference is destroyed. "Predict" when this will happen.
307 SetDead = I == AS.end();
308 deleteValue(Ptr); // Delete all of the pointers from the set
313 bool AliasSetTracker::remove(LoadInst *LI) {
314 unsigned Size = AA.getTargetData().getTypeSize(LI->getType());
315 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
316 if (!AS) return false;
321 bool AliasSetTracker::remove(StoreInst *SI) {
322 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType());
323 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
324 if (!AS) return false;
329 bool AliasSetTracker::remove(CallSite CS) {
330 if (Function *F = CS.getCalledFunction())
331 if (AA.doesNotAccessMemory(F))
332 return false; // doesn't alias anything
334 AliasSet *AS = findAliasSetForCallSite(CS);
335 if (!AS) return false;
340 bool AliasSetTracker::remove(Instruction *I) {
341 // Dispatch to one of the other remove methods...
342 if (LoadInst *LI = dyn_cast<LoadInst>(I))
344 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
346 else if (CallInst *CI = dyn_cast<CallInst>(I))
348 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
354 // deleteValue method - This method is used to remove a pointer value from the
355 // AliasSetTracker entirely. It should be used when an instruction is deleted
356 // from the program to update the AST. If you don't use this, you would have
357 // dangling pointers to deleted instructions.
359 void AliasSetTracker::deleteValue(Value *PtrVal) {
360 // First, look up the PointerRec for this pointer...
361 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
362 if (I == PointerMap.end()) return; // Noop
364 // If we found one, remove the pointer from the alias set it is in.
365 AliasSet::HashNodePair &PtrValEnt = *I;
366 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
368 // Unlink from the list of values...
369 PtrValEnt.second.removeFromList();
370 // Stop using the alias set
376 //===----------------------------------------------------------------------===//
377 // AliasSet/AliasSetTracker Printing Support
378 //===----------------------------------------------------------------------===//
380 void AliasSet::print(std::ostream &OS) const {
381 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
382 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
384 case NoModRef: OS << "No access "; break;
385 case Refs : OS << "Ref "; break;
386 case Mods : OS << "Mod "; break;
387 case ModRef : OS << "Mod/Ref "; break;
388 default: assert(0 && "Bad value for AccessTy!");
390 if (isVolatile()) OS << "[volatile] ";
392 OS << " forwarding to " << (void*)Forward;
395 if (begin() != end()) {
397 for (iterator I = begin(), E = end(); I != E; ++I) {
398 if (I != begin()) OS << ", ";
399 WriteAsOperand(OS << "(", I.getPointer());
400 OS << ", " << I.getSize() << ")";
403 if (!CallSites.empty()) {
404 OS << "\n " << CallSites.size() << " Call Sites: ";
405 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
407 WriteAsOperand(OS, CallSites[i].getCalledValue());
413 void AliasSetTracker::print(std::ostream &OS) const {
414 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
415 << PointerMap.size() << " pointer values.\n";
416 for (const_iterator I = begin(), E = end(); I != E; ++I)
421 void AliasSet::dump() const { print (std::cerr); }
422 void AliasSetTracker::dump() const { print(std::cerr); }
424 //===----------------------------------------------------------------------===//
425 // AliasSetPrinter Pass
426 //===----------------------------------------------------------------------===//
429 class AliasSetPrinter : public FunctionPass {
430 AliasSetTracker *Tracker;
432 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
433 AU.setPreservesAll();
434 AU.addRequired<AliasAnalysis>();
437 virtual bool runOnFunction(Function &F) {
438 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
440 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
445 /// print - Convert to human readable form
446 virtual void print(std::ostream &OS) const {
450 virtual void releaseMemory() {
454 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
455 PassInfo::Analysis | PassInfo::Optimization);