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"
25 /// mergeSetIn - Merge the specified alias set into this alias set...
27 void AliasSet::mergeSetIn(AliasSet &AS) {
28 assert(!AS.Forward && "Alias set is already forwarding!");
29 assert(!Forward && "This set is a forwarding set!!");
31 // Update the alias and access types of this set...
32 AccessTy |= AS.AccessTy;
33 AliasTy |= AS.AliasTy;
35 if (CallSites.empty()) { // Merge call sites...
36 if (!AS.CallSites.empty())
37 std::swap(CallSites, AS.CallSites);
38 } else if (!AS.CallSites.empty()) {
39 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
43 // FIXME: If AS's refcount is zero, nuke it now...
44 assert(RefCount != 0);
46 AS.Forward = this; // Forward across AS now...
47 RefCount++; // AS is now pointing to us...
49 // Merge the list of constituent pointers...
51 *PtrListEnd = AS.PtrList;
52 AS.PtrList->second.setPrevInList(PtrListEnd);
53 PtrListEnd = AS.PtrListEnd;
56 AS.PtrListEnd = &AS.PtrList;
60 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
64 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
65 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
66 AST.removeAliasSet(this);
69 void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry,
71 assert(!Entry.second.hasAliasSet() && "Entry already in set!");
73 AliasAnalysis &AA = AST.getAliasAnalysis();
75 if (isMustAlias()) // Check to see if we have to downgrade to _may_ alias
76 if (HashNodePair *P = getSomePointer()) {
77 AliasAnalysis::AliasResult Result =
78 AA.alias(P->first, P->second.getSize(), Entry.first, Size);
79 if (Result == AliasAnalysis::MayAlias)
81 else // First entry of must alias must have maximum size!
82 P->second.updateSize(Size);
83 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
86 Entry.second.setAliasSet(this);
87 Entry.second.updateSize(Size);
89 // Add it to the end of the list...
90 assert(*PtrListEnd == 0 && "End of list is not null?");
92 PtrListEnd = Entry.second.setPrevInList(PtrListEnd);
93 RefCount++; // Entry points to alias set...
96 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
97 CallSites.push_back(CS);
99 if (Function *F = CS.getCalledFunction()) {
100 if (AA.doesNotAccessMemory(F))
102 else if (AA.onlyReadsMemory(F)) {
109 // FIXME: This should use mod/ref information to make this not suck so bad
114 /// aliasesPointer - Return true if the specified pointer "may" (or must)
115 /// alias one of the members in the set.
117 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
118 AliasAnalysis &AA) const {
119 if (AliasTy == MustAlias) {
120 assert(CallSites.empty() && "Illegal must alias set!");
122 // If this is a set of MustAliases, only check to see if the pointer aliases
123 // SOME value in the set...
124 HashNodePair *SomePtr = getSomePointer();
125 assert(SomePtr && "Empty must-alias set??");
126 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
129 // If this is a may-alias set, we have to check all of the pointers in the set
130 // to be sure it doesn't alias the set...
131 for (iterator I = begin(), E = end(); I != E; ++I)
132 if (AA.alias(Ptr, Size, I->first, I->second.getSize()))
135 // Check the call sites list and invoke list...
136 if (!CallSites.empty())
137 // FIXME: this is pessimistic!
143 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
144 // FIXME: Use mod/ref information to prune this better!
145 if (Function *F = CS.getCalledFunction())
146 if (AA.doesNotAccessMemory(F))
153 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
154 /// instruction referring to the pointer into. If there are multiple alias sets
155 /// that may alias the pointer, merge them together and return the unified set.
157 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
159 AliasSet *FoundSet = 0;
160 for (iterator I = begin(), E = end(); I != E; ++I)
161 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
162 if (FoundSet == 0) { // If this is the first alias set ptr can go into...
163 FoundSet = I; // Remember it.
164 } else { // Otherwise, we must merge the sets...
165 FoundSet->mergeSetIn(*I); // Merge in contents...
172 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
173 AliasSet *FoundSet = 0;
174 for (iterator I = begin(), E = end(); I != E; ++I)
175 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
176 if (FoundSet == 0) { // If this is the first alias set ptr can go into...
177 FoundSet = I; // Remember it.
178 } else if (!I->Forward) { // Otherwise, we must merge the sets...
179 FoundSet->mergeSetIn(*I); // Merge in contents...
189 /// getAliasSetForPointer - Return the alias set that the specified pointer
191 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size){
192 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
194 // Check to see if the pointer is already known...
195 if (Entry.second.hasAliasSet() && Size <= Entry.second.getSize()) {
197 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
198 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
199 // Add it to the alias set it aliases...
200 AS->addPointer(*this, Entry, Size);
203 // Otherwise create a new alias set to hold the loaded pointer...
204 AliasSets.push_back(AliasSet());
205 AliasSets.back().addPointer(*this, Entry, Size);
206 return AliasSets.back();
210 void AliasSetTracker::add(LoadInst *LI) {
212 addPointer(LI->getOperand(0),
213 AA.getTargetData().getTypeSize(LI->getType()), AliasSet::Refs);
214 if (LI->isVolatile()) AS.setVolatile();
217 void AliasSetTracker::add(StoreInst *SI) {
219 addPointer(SI->getOperand(1),
220 AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()),
222 if (SI->isVolatile()) AS.setVolatile();
226 void AliasSetTracker::add(CallSite CS) {
227 if (Function *F = CS.getCalledFunction())
228 if (AA.doesNotAccessMemory(F))
231 AliasSet *AS = findAliasSetForCallSite(CS);
233 AliasSets.push_back(AliasSet());
234 AS = &AliasSets.back();
236 AS->addCallSite(CS, AA);
239 void AliasSetTracker::add(Instruction *I) {
240 // Dispatch to one of the other add methods...
241 if (LoadInst *LI = dyn_cast<LoadInst>(I))
243 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
245 else if (CallInst *CI = dyn_cast<CallInst>(I))
247 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
251 void AliasSetTracker::add(BasicBlock &BB) {
252 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
256 void AliasSetTracker::add(const AliasSetTracker &AST) {
257 assert(&AA == &AST.AA &&
258 "Merging AliasSetTracker objects with different Alias Analyses!");
260 // Loop over all of the alias sets in AST, adding the pointers contained
261 // therein into the current alias sets. This can cause alias sets to be
262 // merged together in the current AST.
263 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
264 if (!I->Forward) { // Ignore forwarding alias sets
265 AliasSet &AS = const_cast<AliasSet&>(*I);
267 // If there are any call sites in the alias set, add them to this AST.
268 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
269 add(AS.CallSites[i]);
271 // Loop over all of the pointers in this alias set...
272 AliasSet::iterator I = AS.begin(), E = AS.end();
274 addPointer(I->first, I->second.getSize(),
275 (AliasSet::AccessType)AS.AccessTy);
280 // remove method - This method is used to remove a pointer value from the
281 // AliasSetTracker entirely. It should be used when an instruction is deleted
282 // from the program to update the AST. If you don't use this, you would have
283 // dangling pointers to deleted instructions.
285 void AliasSetTracker::remove(Value *PtrVal) {
286 // First, look up the PointerRec for this pointer...
287 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
288 if (I == PointerMap.end()) return; // Noop
290 // If we found one, remove the pointer from the alias set it is in.
291 AliasSet::HashNodePair &PtrValEnt = *I;
292 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
294 // Unlink from the list of values...
295 PtrValEnt.second.removeFromList();
296 // Stop using the alias set
297 if (--AS->RefCount == 0)
298 AS->removeFromTracker(*this);
304 //===----------------------------------------------------------------------===//
305 // AliasSet/AliasSetTracker Printing Support
306 //===----------------------------------------------------------------------===//
308 void AliasSet::print(std::ostream &OS) const {
309 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
310 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
312 case NoModRef: OS << "No access "; break;
313 case Refs : OS << "Ref "; break;
314 case Mods : OS << "Mod "; break;
315 case ModRef : OS << "Mod/Ref "; break;
316 default: assert(0 && "Bad value for AccessTy!");
318 if (isVolatile()) OS << "[volatile] ";
320 OS << " forwarding to " << (void*)Forward;
323 if (begin() != end()) {
325 for (iterator I = begin(), E = end(); I != E; ++I) {
326 if (I != begin()) OS << ", ";
327 WriteAsOperand(OS << "(", I->first);
328 OS << ", " << I->second.getSize() << ")";
331 if (!CallSites.empty()) {
332 OS << "\n " << CallSites.size() << " Call Sites: ";
333 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
335 WriteAsOperand(OS, CallSites[i].getCalledValue());
341 void AliasSetTracker::print(std::ostream &OS) const {
342 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
343 << PointerMap.size() << " pointer values.\n";
344 for (const_iterator I = begin(), E = end(); I != E; ++I)
349 void AliasSet::dump() const { print (std::cerr); }
350 void AliasSetTracker::dump() const { print(std::cerr); }
352 //===----------------------------------------------------------------------===//
353 // AliasSetPrinter Pass
354 //===----------------------------------------------------------------------===//
357 class AliasSetPrinter : public FunctionPass {
358 AliasSetTracker *Tracker;
360 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
361 AU.setPreservesAll();
362 AU.addRequired<AliasAnalysis>();
365 virtual bool runOnFunction(Function &F) {
366 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
368 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
373 /// print - Convert to human readable form
374 virtual void print(std::ostream &OS) const {
378 virtual void releaseMemory() {
382 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
383 PassInfo::Analysis | PassInfo::Optimization);