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1 //===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===//
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 the AliasSetTracker and AliasSet classes.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/AliasSetTracker.h"
15 #include "llvm/Analysis/AliasAnalysis.h"
16 #include "llvm/IR/DataLayout.h"
17 #include "llvm/IR/InstIterator.h"
18 #include "llvm/IR/Instructions.h"
19 #include "llvm/IR/IntrinsicInst.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/IR/Type.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/raw_ostream.h"
28 /// mergeSetIn - Merge the specified alias set into this alias set.
30 void AliasSet::mergeSetIn(AliasSet
&AS
, AliasSetTracker
&AST
) {
31 assert(!AS
.Forward
&& "Alias set is already forwarding!");
32 assert(!Forward
&& "This set is a forwarding set!!");
34 // Update the alias and access types of this set...
35 AccessTy
|= AS
.AccessTy
;
36 AliasTy
|= AS
.AliasTy
;
37 Volatile
|= AS
.Volatile
;
39 if (AliasTy
== MustAlias
) {
40 // Check that these two merged sets really are must aliases. Since both
41 // used to be must-alias sets, we can just check any pointer from each set
43 AliasAnalysis
&AA
= AST
.getAliasAnalysis();
44 PointerRec
*L
= getSomePointer();
45 PointerRec
*R
= AS
.getSomePointer();
47 // If the pointers are not a must-alias pair, this set becomes a may alias.
48 if (AA
.alias(AliasAnalysis::Location(L
->getValue(),
51 AliasAnalysis::Location(R
->getValue(),
54 != AliasAnalysis::MustAlias
)
58 bool ASHadUnknownInsts
= !AS
.UnknownInsts
.empty();
59 if (UnknownInsts
.empty()) { // Merge call sites...
60 if (ASHadUnknownInsts
) {
61 std::swap(UnknownInsts
, AS
.UnknownInsts
);
64 } else if (ASHadUnknownInsts
) {
65 UnknownInsts
.insert(UnknownInsts
.end(), AS
.UnknownInsts
.begin(), AS
.UnknownInsts
.end());
66 AS
.UnknownInsts
.clear();
69 AS
.Forward
= this; // Forward across AS now...
70 addRef(); // AS is now pointing to us...
72 // Merge the list of constituent pointers...
74 *PtrListEnd
= AS
.PtrList
;
75 AS
.PtrList
->setPrevInList(PtrListEnd
);
76 PtrListEnd
= AS
.PtrListEnd
;
79 AS
.PtrListEnd
= &AS
.PtrList
;
80 assert(*AS
.PtrListEnd
== nullptr && "End of list is not null?");
82 if (ASHadUnknownInsts
)
86 void AliasSetTracker::removeAliasSet(AliasSet
*AS
) {
87 if (AliasSet
*Fwd
= AS
->Forward
) {
89 AS
->Forward
= nullptr;
94 void AliasSet::removeFromTracker(AliasSetTracker
&AST
) {
95 assert(RefCount
== 0 && "Cannot remove non-dead alias set from tracker!");
96 AST
.removeAliasSet(this);
99 void AliasSet::addPointer(AliasSetTracker
&AST
, PointerRec
&Entry
,
100 uint64_t Size
, const AAMDNodes
&AAInfo
,
101 bool KnownMustAlias
) {
102 assert(!Entry
.hasAliasSet() && "Entry already in set!");
104 // Check to see if we have to downgrade to _may_ alias.
105 if (isMustAlias() && !KnownMustAlias
)
106 if (PointerRec
*P
= getSomePointer()) {
107 AliasAnalysis
&AA
= AST
.getAliasAnalysis();
108 AliasAnalysis::AliasResult Result
=
109 AA
.alias(AliasAnalysis::Location(P
->getValue(), P
->getSize(),
111 AliasAnalysis::Location(Entry
.getValue(), Size
, AAInfo
));
112 if (Result
!= AliasAnalysis::MustAlias
)
114 else // First entry of must alias must have maximum size!
115 P
->updateSizeAndAAInfo(Size
, AAInfo
);
116 assert(Result
!= AliasAnalysis::NoAlias
&& "Cannot be part of must set!");
119 Entry
.setAliasSet(this);
120 Entry
.updateSizeAndAAInfo(Size
, AAInfo
);
122 // Add it to the end of the list...
123 assert(*PtrListEnd
== nullptr && "End of list is not null?");
124 *PtrListEnd
= &Entry
;
125 PtrListEnd
= Entry
.setPrevInList(PtrListEnd
);
126 assert(*PtrListEnd
== nullptr && "End of list is not null?");
127 addRef(); // Entry points to alias set.
130 void AliasSet::addUnknownInst(Instruction
*I
, AliasAnalysis
&AA
) {
131 if (UnknownInsts
.empty())
133 UnknownInsts
.push_back(I
);
135 if (!I
->mayWriteToMemory()) {
141 // FIXME: This should use mod/ref information to make this not suck so bad
146 /// aliasesPointer - Return true if the specified pointer "may" (or must)
147 /// alias one of the members in the set.
149 bool AliasSet::aliasesPointer(const Value
*Ptr
, uint64_t Size
,
150 const AAMDNodes
&AAInfo
,
151 AliasAnalysis
&AA
) const {
152 if (AliasTy
== MustAlias
) {
153 assert(UnknownInsts
.empty() && "Illegal must alias set!");
155 // If this is a set of MustAliases, only check to see if the pointer aliases
156 // SOME value in the set.
157 PointerRec
*SomePtr
= getSomePointer();
158 assert(SomePtr
&& "Empty must-alias set??");
159 return AA
.alias(AliasAnalysis::Location(SomePtr
->getValue(),
161 SomePtr
->getAAInfo()),
162 AliasAnalysis::Location(Ptr
, Size
, AAInfo
));
165 // If this is a may-alias set, we have to check all of the pointers in the set
166 // to be sure it doesn't alias the set...
167 for (iterator I
= begin(), E
= end(); I
!= E
; ++I
)
168 if (AA
.alias(AliasAnalysis::Location(Ptr
, Size
, AAInfo
),
169 AliasAnalysis::Location(I
.getPointer(), I
.getSize(),
173 // Check the unknown instructions...
174 if (!UnknownInsts
.empty()) {
175 for (unsigned i
= 0, e
= UnknownInsts
.size(); i
!= e
; ++i
)
176 if (AA
.getModRefInfo(UnknownInsts
[i
],
177 AliasAnalysis::Location(Ptr
, Size
, AAInfo
)) !=
178 AliasAnalysis::NoModRef
)
185 bool AliasSet::aliasesUnknownInst(Instruction
*Inst
, AliasAnalysis
&AA
) const {
186 if (!Inst
->mayReadOrWriteMemory())
189 for (unsigned i
= 0, e
= UnknownInsts
.size(); i
!= e
; ++i
) {
190 CallSite C1
= getUnknownInst(i
), C2
= Inst
;
192 AA
.getModRefInfo(C1
, C2
) != AliasAnalysis::NoModRef
||
193 AA
.getModRefInfo(C2
, C1
) != AliasAnalysis::NoModRef
)
197 for (iterator I
= begin(), E
= end(); I
!= E
; ++I
)
198 if (AA
.getModRefInfo(Inst
, AliasAnalysis::Location(I
.getPointer(),
201 AliasAnalysis::NoModRef
)
207 void AliasSetTracker::clear() {
208 // Delete all the PointerRec entries.
209 for (PointerMapType::iterator I
= PointerMap
.begin(), E
= PointerMap
.end();
211 I
->second
->eraseFromList();
215 // The alias sets should all be clear now.
220 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
221 /// instruction referring to the pointer into. If there are multiple alias sets
222 /// that may alias the pointer, merge them together and return the unified set.
224 AliasSet
*AliasSetTracker::findAliasSetForPointer(const Value
*Ptr
,
226 const AAMDNodes
&AAInfo
) {
227 AliasSet
*FoundSet
= nullptr;
228 for (iterator I
= begin(), E
= end(); I
!= E
;) {
230 if (Cur
->Forward
|| !Cur
->aliasesPointer(Ptr
, Size
, AAInfo
, AA
)) continue;
232 if (!FoundSet
) { // If this is the first alias set ptr can go into.
233 FoundSet
= Cur
; // Remember it.
234 } else { // Otherwise, we must merge the sets.
235 FoundSet
->mergeSetIn(*Cur
, *this); // Merge in contents.
242 /// containsPointer - Return true if the specified location is represented by
243 /// this alias set, false otherwise. This does not modify the AST object or
245 bool AliasSetTracker::containsPointer(Value
*Ptr
, uint64_t Size
,
246 const AAMDNodes
&AAInfo
) const {
247 for (const_iterator I
= begin(), E
= end(); I
!= E
; ++I
)
248 if (!I
->Forward
&& I
->aliasesPointer(Ptr
, Size
, AAInfo
, AA
))
253 bool AliasSetTracker::containsUnknown(Instruction
*Inst
) const {
254 for (const_iterator I
= begin(), E
= end(); I
!= E
; ++I
)
255 if (!I
->Forward
&& I
->aliasesUnknownInst(Inst
, AA
))
260 AliasSet
*AliasSetTracker::findAliasSetForUnknownInst(Instruction
*Inst
) {
261 AliasSet
*FoundSet
= nullptr;
262 for (iterator I
= begin(), E
= end(); I
!= E
;) {
264 if (Cur
->Forward
|| !Cur
->aliasesUnknownInst(Inst
, AA
))
266 if (!FoundSet
) // If this is the first alias set ptr can go into.
267 FoundSet
= Cur
; // Remember it.
268 else if (!Cur
->Forward
) // Otherwise, we must merge the sets.
269 FoundSet
->mergeSetIn(*Cur
, *this); // Merge in contents.
277 /// getAliasSetForPointer - Return the alias set that the specified pointer
279 AliasSet
&AliasSetTracker::getAliasSetForPointer(Value
*Pointer
, uint64_t Size
,
280 const AAMDNodes
&AAInfo
,
282 AliasSet::PointerRec
&Entry
= getEntryFor(Pointer
);
284 // Check to see if the pointer is already known.
285 if (Entry
.hasAliasSet()) {
286 Entry
.updateSizeAndAAInfo(Size
, AAInfo
);
288 return *Entry
.getAliasSet(*this)->getForwardedTarget(*this);
291 if (AliasSet
*AS
= findAliasSetForPointer(Pointer
, Size
, AAInfo
)) {
292 // Add it to the alias set it aliases.
293 AS
->addPointer(*this, Entry
, Size
, AAInfo
);
297 if (New
) *New
= true;
298 // Otherwise create a new alias set to hold the loaded pointer.
299 AliasSets
.push_back(new AliasSet());
300 AliasSets
.back().addPointer(*this, Entry
, Size
, AAInfo
);
301 return AliasSets
.back();
304 bool AliasSetTracker::add(Value
*Ptr
, uint64_t Size
, const AAMDNodes
&AAInfo
) {
306 addPointer(Ptr
, Size
, AAInfo
, AliasSet::NoModRef
, NewPtr
);
311 bool AliasSetTracker::add(LoadInst
*LI
) {
312 if (LI
->getOrdering() > Monotonic
) return addUnknown(LI
);
315 LI
->getAAMetadata(AAInfo
);
317 AliasSet::AccessType ATy
= AliasSet::Refs
;
319 AliasSet
&AS
= addPointer(LI
->getOperand(0),
320 AA
.getTypeStoreSize(LI
->getType()),
321 AAInfo
, ATy
, NewPtr
);
322 if (LI
->isVolatile()) AS
.setVolatile();
326 bool AliasSetTracker::add(StoreInst
*SI
) {
327 if (SI
->getOrdering() > Monotonic
) return addUnknown(SI
);
330 SI
->getAAMetadata(AAInfo
);
332 AliasSet::AccessType ATy
= AliasSet::Mods
;
334 Value
*Val
= SI
->getOperand(0);
335 AliasSet
&AS
= addPointer(SI
->getOperand(1),
336 AA
.getTypeStoreSize(Val
->getType()),
337 AAInfo
, ATy
, NewPtr
);
338 if (SI
->isVolatile()) AS
.setVolatile();
342 bool AliasSetTracker::add(VAArgInst
*VAAI
) {
344 VAAI
->getAAMetadata(AAInfo
);
347 addPointer(VAAI
->getOperand(0), AliasAnalysis::UnknownSize
,
348 AAInfo
, AliasSet::ModRef
, NewPtr
);
353 bool AliasSetTracker::addUnknown(Instruction
*Inst
) {
354 if (isa
<DbgInfoIntrinsic
>(Inst
))
355 return true; // Ignore DbgInfo Intrinsics.
356 if (!Inst
->mayReadOrWriteMemory())
357 return true; // doesn't alias anything
359 AliasSet
*AS
= findAliasSetForUnknownInst(Inst
);
361 AS
->addUnknownInst(Inst
, AA
);
364 AliasSets
.push_back(new AliasSet());
365 AS
= &AliasSets
.back();
366 AS
->addUnknownInst(Inst
, AA
);
370 bool AliasSetTracker::add(Instruction
*I
) {
371 // Dispatch to one of the other add methods.
372 if (LoadInst
*LI
= dyn_cast
<LoadInst
>(I
))
374 if (StoreInst
*SI
= dyn_cast
<StoreInst
>(I
))
376 if (VAArgInst
*VAAI
= dyn_cast
<VAArgInst
>(I
))
378 return addUnknown(I
);
381 void AliasSetTracker::add(BasicBlock
&BB
) {
382 for (BasicBlock::iterator I
= BB
.begin(), E
= BB
.end(); I
!= E
; ++I
)
386 void AliasSetTracker::add(const AliasSetTracker
&AST
) {
387 assert(&AA
== &AST
.AA
&&
388 "Merging AliasSetTracker objects with different Alias Analyses!");
390 // Loop over all of the alias sets in AST, adding the pointers contained
391 // therein into the current alias sets. This can cause alias sets to be
392 // merged together in the current AST.
393 for (const_iterator I
= AST
.begin(), E
= AST
.end(); I
!= E
; ++I
) {
394 if (I
->Forward
) continue; // Ignore forwarding alias sets
396 AliasSet
&AS
= const_cast<AliasSet
&>(*I
);
398 // If there are any call sites in the alias set, add them to this AST.
399 for (unsigned i
= 0, e
= AS
.UnknownInsts
.size(); i
!= e
; ++i
)
400 add(AS
.UnknownInsts
[i
]);
402 // Loop over all of the pointers in this alias set.
404 for (AliasSet::iterator ASI
= AS
.begin(), E
= AS
.end(); ASI
!= E
; ++ASI
) {
405 AliasSet
&NewAS
= addPointer(ASI
.getPointer(), ASI
.getSize(),
407 (AliasSet::AccessType
)AS
.AccessTy
, X
);
408 if (AS
.isVolatile()) NewAS
.setVolatile();
413 /// remove - Remove the specified (potentially non-empty) alias set from the
415 void AliasSetTracker::remove(AliasSet
&AS
) {
416 // Drop all call sites.
417 if (!AS
.UnknownInsts
.empty())
419 AS
.UnknownInsts
.clear();
421 // Clear the alias set.
422 unsigned NumRefs
= 0;
423 while (!AS
.empty()) {
424 AliasSet::PointerRec
*P
= AS
.PtrList
;
426 Value
*ValToRemove
= P
->getValue();
428 // Unlink and delete entry from the list of values.
431 // Remember how many references need to be dropped.
434 // Finally, remove the entry.
435 PointerMap
.erase(ValToRemove
);
438 // Stop using the alias set, removing it.
439 AS
.RefCount
-= NumRefs
;
440 if (AS
.RefCount
== 0)
441 AS
.removeFromTracker(*this);
445 AliasSetTracker::remove(Value
*Ptr
, uint64_t Size
, const AAMDNodes
&AAInfo
) {
446 AliasSet
*AS
= findAliasSetForPointer(Ptr
, Size
, AAInfo
);
447 if (!AS
) return false;
452 bool AliasSetTracker::remove(LoadInst
*LI
) {
453 uint64_t Size
= AA
.getTypeStoreSize(LI
->getType());
456 LI
->getAAMetadata(AAInfo
);
458 AliasSet
*AS
= findAliasSetForPointer(LI
->getOperand(0), Size
, AAInfo
);
459 if (!AS
) return false;
464 bool AliasSetTracker::remove(StoreInst
*SI
) {
465 uint64_t Size
= AA
.getTypeStoreSize(SI
->getOperand(0)->getType());
468 SI
->getAAMetadata(AAInfo
);
470 AliasSet
*AS
= findAliasSetForPointer(SI
->getOperand(1), Size
, AAInfo
);
471 if (!AS
) return false;
476 bool AliasSetTracker::remove(VAArgInst
*VAAI
) {
478 VAAI
->getAAMetadata(AAInfo
);
480 AliasSet
*AS
= findAliasSetForPointer(VAAI
->getOperand(0),
481 AliasAnalysis::UnknownSize
, AAInfo
);
482 if (!AS
) return false;
487 bool AliasSetTracker::removeUnknown(Instruction
*I
) {
488 if (!I
->mayReadOrWriteMemory())
489 return false; // doesn't alias anything
491 AliasSet
*AS
= findAliasSetForUnknownInst(I
);
492 if (!AS
) return false;
497 bool AliasSetTracker::remove(Instruction
*I
) {
498 // Dispatch to one of the other remove methods...
499 if (LoadInst
*LI
= dyn_cast
<LoadInst
>(I
))
501 if (StoreInst
*SI
= dyn_cast
<StoreInst
>(I
))
503 if (VAArgInst
*VAAI
= dyn_cast
<VAArgInst
>(I
))
505 return removeUnknown(I
);
509 // deleteValue method - This method is used to remove a pointer value from the
510 // AliasSetTracker entirely. It should be used when an instruction is deleted
511 // from the program to update the AST. If you don't use this, you would have
512 // dangling pointers to deleted instructions.
514 void AliasSetTracker::deleteValue(Value
*PtrVal
) {
515 // Notify the alias analysis implementation that this value is gone.
516 AA
.deleteValue(PtrVal
);
518 // If this is a call instruction, remove the callsite from the appropriate
519 // AliasSet (if present).
520 if (Instruction
*Inst
= dyn_cast
<Instruction
>(PtrVal
)) {
521 if (Inst
->mayReadOrWriteMemory()) {
522 // Scan all the alias sets to see if this call site is contained.
523 for (iterator I
= begin(), E
= end(); I
!= E
;) {
526 Cur
->removeUnknownInst(*this, Inst
);
531 // First, look up the PointerRec for this pointer.
532 PointerMapType::iterator I
= PointerMap
.find_as(PtrVal
);
533 if (I
== PointerMap
.end()) return; // Noop
535 // If we found one, remove the pointer from the alias set it is in.
536 AliasSet::PointerRec
*PtrValEnt
= I
->second
;
537 AliasSet
*AS
= PtrValEnt
->getAliasSet(*this);
539 // Unlink and delete from the list of values.
540 PtrValEnt
->eraseFromList();
542 // Stop using the alias set.
548 // copyValue - This method should be used whenever a preexisting value in the
549 // program is copied or cloned, introducing a new value. Note that it is ok for
550 // clients that use this method to introduce the same value multiple times: if
551 // the tracker already knows about a value, it will ignore the request.
553 void AliasSetTracker::copyValue(Value
*From
, Value
*To
) {
554 // Notify the alias analysis implementation that this value is copied.
555 AA
.copyValue(From
, To
);
557 // First, look up the PointerRec for this pointer.
558 PointerMapType::iterator I
= PointerMap
.find_as(From
);
559 if (I
== PointerMap
.end())
561 assert(I
->second
->hasAliasSet() && "Dead entry?");
563 AliasSet::PointerRec
&Entry
= getEntryFor(To
);
564 if (Entry
.hasAliasSet()) return; // Already in the tracker!
566 // Add it to the alias set it aliases...
567 I
= PointerMap
.find_as(From
);
568 AliasSet
*AS
= I
->second
->getAliasSet(*this);
569 AS
->addPointer(*this, Entry
, I
->second
->getSize(),
570 I
->second
->getAAInfo(),
576 //===----------------------------------------------------------------------===//
577 // AliasSet/AliasSetTracker Printing Support
578 //===----------------------------------------------------------------------===//
580 void AliasSet::print(raw_ostream
&OS
) const {
581 OS
<< " AliasSet[" << (const void*)this << ", " << RefCount
<< "] ";
582 OS
<< (AliasTy
== MustAlias
? "must" : "may") << " alias, ";
584 case NoModRef
: OS
<< "No access "; break;
585 case Refs
: OS
<< "Ref "; break;
586 case Mods
: OS
<< "Mod "; break;
587 case ModRef
: OS
<< "Mod/Ref "; break;
588 default: llvm_unreachable("Bad value for AccessTy!");
590 if (isVolatile()) OS
<< "[volatile] ";
592 OS
<< " forwarding to " << (void*)Forward
;
597 for (iterator I
= begin(), E
= end(); I
!= E
; ++I
) {
598 if (I
!= begin()) OS
<< ", ";
599 I
.getPointer()->printAsOperand(OS
<< "(");
600 OS
<< ", " << I
.getSize() << ")";
603 if (!UnknownInsts
.empty()) {
604 OS
<< "\n " << UnknownInsts
.size() << " Unknown instructions: ";
605 for (unsigned i
= 0, e
= UnknownInsts
.size(); i
!= e
; ++i
) {
607 UnknownInsts
[i
]->printAsOperand(OS
);
613 void AliasSetTracker::print(raw_ostream
&OS
) const {
614 OS
<< "Alias Set Tracker: " << AliasSets
.size() << " alias sets for "
615 << PointerMap
.size() << " pointer values.\n";
616 for (const_iterator I
= begin(), E
= end(); I
!= E
; ++I
)
621 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
622 void AliasSet::dump() const { print(dbgs()); }
623 void AliasSetTracker::dump() const { print(dbgs()); }
626 //===----------------------------------------------------------------------===//
627 // ASTCallbackVH Class Implementation
628 //===----------------------------------------------------------------------===//
630 void AliasSetTracker::ASTCallbackVH::deleted() {
631 assert(AST
&& "ASTCallbackVH called with a null AliasSetTracker!");
632 AST
->deleteValue(getValPtr());
636 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value
*V
) {
637 AST
->copyValue(getValPtr(), V
);
640 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value
*V
, AliasSetTracker
*ast
)
641 : CallbackVH(V
), AST(ast
) {}
643 AliasSetTracker::ASTCallbackVH
&
644 AliasSetTracker::ASTCallbackVH::operator=(Value
*V
) {
645 return *this = ASTCallbackVH(V
, AST
);
648 //===----------------------------------------------------------------------===//
649 // AliasSetPrinter Pass
650 //===----------------------------------------------------------------------===//
653 class AliasSetPrinter
: public FunctionPass
{
654 AliasSetTracker
*Tracker
;
656 static char ID
; // Pass identification, replacement for typeid
657 AliasSetPrinter() : FunctionPass(ID
) {
658 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
661 void getAnalysisUsage(AnalysisUsage
&AU
) const override
{
662 AU
.setPreservesAll();
663 AU
.addRequired
<AliasAnalysis
>();
666 bool runOnFunction(Function
&F
) override
{
667 Tracker
= new AliasSetTracker(getAnalysis
<AliasAnalysis
>());
669 for (inst_iterator I
= inst_begin(F
), E
= inst_end(F
); I
!= E
; ++I
)
671 Tracker
->print(errs());
678 char AliasSetPrinter::ID
= 0;
679 INITIALIZE_PASS_BEGIN(AliasSetPrinter
, "print-alias-sets",
680 "Alias Set Printer", false, true)
681 INITIALIZE_AG_DEPENDENCY(AliasAnalysis
)
682 INITIALIZE_PASS_END(AliasSetPrinter
, "print-alias-sets",
683 "Alias Set Printer", false, true)