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) {
97 CallSites.push_back(CS);
98 AliasTy = MayAlias; // FIXME: Too conservative?
102 /// aliasesPointer - Return true if the specified pointer "may" (or must)
103 /// alias one of the members in the set.
105 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
106 AliasAnalysis &AA) const {
107 if (AliasTy == MustAlias) {
108 assert(CallSites.empty() && "Illegal must alias set!");
110 // If this is a set of MustAliases, only check to see if the pointer aliases
111 // SOME value in the set...
112 HashNodePair *SomePtr = getSomePointer();
113 assert(SomePtr && "Empty must-alias set??");
114 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
117 // If this is a may-alias set, we have to check all of the pointers in the set
118 // to be sure it doesn't alias the set...
119 for (iterator I = begin(), E = end(); I != E; ++I)
120 if (AA.alias(Ptr, Size, I->first, I->second.getSize()))
123 // Check the call sites list and invoke list...
124 if (!CallSites.empty())
125 // FIXME: this is pessimistic!
131 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
132 // FIXME: Too conservative!
137 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
138 /// instruction referring to the pointer into. If there are multiple alias sets
139 /// that may alias the pointer, merge them together and return the unified set.
141 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
143 AliasSet *FoundSet = 0;
144 for (iterator I = begin(), E = end(); I != E; ++I)
145 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
146 if (FoundSet == 0) { // If this is the first alias set ptr can go into...
147 FoundSet = I; // Remember it.
148 } else { // Otherwise, we must merge the sets...
149 FoundSet->mergeSetIn(*I); // Merge in contents...
156 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
157 AliasSet *FoundSet = 0;
158 for (iterator I = begin(), E = end(); I != E; ++I)
159 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
160 if (FoundSet == 0) { // If this is the first alias set ptr can go into...
161 FoundSet = I; // Remember it.
162 } else if (!I->Forward) { // Otherwise, we must merge the sets...
163 FoundSet->mergeSetIn(*I); // Merge in contents...
173 /// getAliasSetForPointer - Return the alias set that the specified pointer
175 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size){
176 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
178 // Check to see if the pointer is already known...
179 if (Entry.second.hasAliasSet() && Size <= Entry.second.getSize()) {
181 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
182 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
183 // Add it to the alias set it aliases...
184 AS->addPointer(*this, Entry, Size);
187 // Otherwise create a new alias set to hold the loaded pointer...
188 AliasSets.push_back(AliasSet());
189 AliasSets.back().addPointer(*this, Entry, Size);
190 return AliasSets.back();
194 void AliasSetTracker::add(LoadInst *LI) {
196 addPointer(LI->getOperand(0),
197 AA.getTargetData().getTypeSize(LI->getType()), AliasSet::Refs);
198 if (LI->isVolatile()) AS.setVolatile();
201 void AliasSetTracker::add(StoreInst *SI) {
203 addPointer(SI->getOperand(1),
204 AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()),
206 if (SI->isVolatile()) AS.setVolatile();
210 void AliasSetTracker::add(CallSite CS) {
211 AliasSet *AS = findAliasSetForCallSite(CS);
213 AliasSets.push_back(AliasSet());
214 AS = &AliasSets.back();
219 void AliasSetTracker::add(Instruction *I) {
220 // Dispatch to one of the other add methods...
221 if (LoadInst *LI = dyn_cast<LoadInst>(I))
223 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
225 else if (CallInst *CI = dyn_cast<CallInst>(I))
227 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
231 void AliasSetTracker::add(BasicBlock &BB) {
232 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
236 void AliasSetTracker::add(const AliasSetTracker &AST) {
237 assert(&AA == &AST.AA &&
238 "Merging AliasSetTracker objects with different Alias Analyses!");
240 // Loop over all of the alias sets in AST, adding the pointers contained
241 // therein into the current alias sets. This can cause alias sets to be
242 // merged together in the current AST.
243 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
244 if (!I->Forward) { // Ignore forwarding alias sets
245 AliasSet &AS = const_cast<AliasSet&>(*I);
247 // If there are any call sites in the alias set, add them to this AST.
248 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
249 add(AS.CallSites[i]);
251 // Loop over all of the pointers in this alias set...
252 AliasSet::iterator I = AS.begin(), E = AS.end();
254 addPointer(I->first, I->second.getSize(),
255 (AliasSet::AccessType)AS.AccessTy);
260 // remove method - This method is used to remove a pointer value from the
261 // AliasSetTracker entirely. It should be used when an instruction is deleted
262 // from the program to update the AST. If you don't use this, you would have
263 // dangling pointers to deleted instructions.
265 void AliasSetTracker::remove(Value *PtrVal) {
266 // First, look up the PointerRec for this pointer...
267 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
268 if (I == PointerMap.end()) return; // Noop
270 // If we found one, remove the pointer from the alias set it is in.
271 AliasSet::HashNodePair &PtrValEnt = *I;
272 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
274 // Unlink from the list of values...
275 PtrValEnt.second.removeFromList();
276 // Stop using the alias set
277 if (--AS->RefCount == 0)
278 AS->removeFromTracker(*this);
284 //===----------------------------------------------------------------------===//
285 // AliasSet/AliasSetTracker Printing Support
286 //===----------------------------------------------------------------------===//
288 void AliasSet::print(std::ostream &OS) const {
289 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
290 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
292 case NoModRef: OS << "No access "; break;
293 case Refs : OS << "Ref "; break;
294 case Mods : OS << "Mod "; break;
295 case ModRef : OS << "Mod/Ref "; break;
296 default: assert(0 && "Bad value for AccessTy!");
298 if (isVolatile()) OS << "[volatile] ";
300 OS << " forwarding to " << (void*)Forward;
303 if (begin() != end()) {
305 for (iterator I = begin(), E = end(); I != E; ++I) {
306 if (I != begin()) OS << ", ";
307 WriteAsOperand(OS << "(", I->first);
308 OS << ", " << I->second.getSize() << ")";
311 if (!CallSites.empty()) {
312 OS << "\n " << CallSites.size() << " Call Sites: ";
313 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
315 WriteAsOperand(OS, CallSites[i].getCalledValue());
321 void AliasSetTracker::print(std::ostream &OS) const {
322 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
323 << PointerMap.size() << " pointer values.\n";
324 for (const_iterator I = begin(), E = end(); I != E; ++I)
329 void AliasSet::dump() const { print (std::cerr); }
330 void AliasSetTracker::dump() const { print(std::cerr); }
332 //===----------------------------------------------------------------------===//
333 // AliasSetPrinter Pass
334 //===----------------------------------------------------------------------===//
337 class AliasSetPrinter : public FunctionPass {
338 AliasSetTracker *Tracker;
340 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
341 AU.setPreservesAll();
342 AU.addRequired<AliasAnalysis>();
345 virtual bool runOnFunction(Function &F) {
346 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
348 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
353 /// print - Convert to human readable form
354 virtual void print(std::ostream &OS) const {
358 virtual void releaseMemory() {
362 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
363 PassInfo::Analysis | PassInfo::Optimization);