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/Analysis/MemoryLocation.h"
17 #include "llvm/IR/CallSite.h"
18 #include "llvm/IR/Constants.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/Function.h"
21 #include "llvm/IR/InstIterator.h"
22 #include "llvm/IR/Instruction.h"
23 #include "llvm/IR/Instructions.h"
24 #include "llvm/IR/IntrinsicInst.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/IR/Value.h"
27 #include "llvm/Pass.h"
28 #include "llvm/Support/AtomicOrdering.h"
29 #include "llvm/Support/Casting.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/Compiler.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/raw_ostream.h"
41 static cl::opt<unsigned>
42 SaturationThreshold("alias-set-saturation-threshold", cl::Hidden,
44 cl::desc("The maximum number of pointers may-alias "
45 "sets may contain before degradation"));
47 /// mergeSetIn - Merge the specified alias set into this alias set.
49 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
50 assert(!AS.Forward && "Alias set is already forwarding!");
51 assert(!Forward && "This set is a forwarding set!!");
53 bool WasMustAlias = (Alias == SetMustAlias);
54 // Update the alias and access types of this set...
57 Volatile |= AS.Volatile;
59 if (Alias == SetMustAlias) {
60 // Check that these two merged sets really are must aliases. Since both
61 // used to be must-alias sets, we can just check any pointer from each set
63 AliasAnalysis &AA = AST.getAliasAnalysis();
64 PointerRec *L = getSomePointer();
65 PointerRec *R = AS.getSomePointer();
67 // If the pointers are not a must-alias pair, this set becomes a may alias.
68 if (AA.alias(MemoryLocation(L->getValue(), L->getSize(), L->getAAInfo()),
69 MemoryLocation(R->getValue(), R->getSize(), R->getAAInfo())) !=
74 if (Alias == SetMayAlias) {
76 AST.TotalMayAliasSetSize += size();
77 if (AS.Alias == SetMustAlias)
78 AST.TotalMayAliasSetSize += AS.size();
81 bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
82 if (UnknownInsts.empty()) { // Merge call sites...
83 if (ASHadUnknownInsts) {
84 std::swap(UnknownInsts, AS.UnknownInsts);
87 } else if (ASHadUnknownInsts) {
88 UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
89 AS.UnknownInsts.clear();
92 AS.Forward = this; // Forward across AS now...
93 addRef(); // AS is now pointing to us...
95 // Merge the list of constituent pointers...
99 *PtrListEnd = AS.PtrList;
100 AS.PtrList->setPrevInList(PtrListEnd);
101 PtrListEnd = AS.PtrListEnd;
103 AS.PtrList = nullptr;
104 AS.PtrListEnd = &AS.PtrList;
105 assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
107 if (ASHadUnknownInsts)
111 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
112 if (AliasSet *Fwd = AS->Forward) {
114 AS->Forward = nullptr;
117 if (AS->Alias == AliasSet::SetMayAlias)
118 TotalMayAliasSetSize -= AS->size();
123 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
124 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
125 AST.removeAliasSet(this);
128 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
129 uint64_t Size, const AAMDNodes &AAInfo,
130 bool KnownMustAlias) {
131 assert(!Entry.hasAliasSet() && "Entry already in set!");
133 // Check to see if we have to downgrade to _may_ alias.
134 if (isMustAlias() && !KnownMustAlias)
135 if (PointerRec *P = getSomePointer()) {
136 AliasAnalysis &AA = AST.getAliasAnalysis();
138 AA.alias(MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
139 MemoryLocation(Entry.getValue(), Size, AAInfo));
140 if (Result != MustAlias) {
142 AST.TotalMayAliasSetSize += size();
144 // First entry of must alias must have maximum size!
145 P->updateSizeAndAAInfo(Size, AAInfo);
147 assert(Result != NoAlias && "Cannot be part of must set!");
150 Entry.setAliasSet(this);
151 Entry.updateSizeAndAAInfo(Size, AAInfo);
153 // Add it to the end of the list...
155 assert(*PtrListEnd == nullptr && "End of list is not null?");
156 *PtrListEnd = &Entry;
157 PtrListEnd = Entry.setPrevInList(PtrListEnd);
158 assert(*PtrListEnd == nullptr && "End of list is not null?");
159 // Entry points to alias set.
162 if (Alias == SetMayAlias)
163 AST.TotalMayAliasSetSize++;
166 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
167 if (UnknownInsts.empty())
169 UnknownInsts.emplace_back(I);
171 if (!I->mayWriteToMemory()) {
177 // FIXME: This should use mod/ref information to make this not suck so bad
179 Access = ModRefAccess;
182 /// aliasesPointer - Return true if the specified pointer "may" (or must)
183 /// alias one of the members in the set.
185 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
186 const AAMDNodes &AAInfo,
187 AliasAnalysis &AA) const {
191 if (Alias == SetMustAlias) {
192 assert(UnknownInsts.empty() && "Illegal must alias set!");
194 // If this is a set of MustAliases, only check to see if the pointer aliases
195 // SOME value in the set.
196 PointerRec *SomePtr = getSomePointer();
197 assert(SomePtr && "Empty must-alias set??");
198 return AA.alias(MemoryLocation(SomePtr->getValue(), SomePtr->getSize(),
199 SomePtr->getAAInfo()),
200 MemoryLocation(Ptr, Size, AAInfo));
203 // If this is a may-alias set, we have to check all of the pointers in the set
204 // to be sure it doesn't alias the set...
205 for (iterator I = begin(), E = end(); I != E; ++I)
206 if (AA.alias(MemoryLocation(Ptr, Size, AAInfo),
207 MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
210 // Check the unknown instructions...
211 if (!UnknownInsts.empty()) {
212 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
213 if (auto *Inst = getUnknownInst(i))
215 AA.getModRefInfo(Inst, MemoryLocation(Ptr, Size, AAInfo))))
222 bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
223 AliasAnalysis &AA) const {
228 if (!Inst->mayReadOrWriteMemory())
231 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
232 if (auto *UnknownInst = getUnknownInst(i)) {
233 ImmutableCallSite C1(UnknownInst), C2(Inst);
234 if (!C1 || !C2 || isModOrRefSet(AA.getModRefInfo(C1, C2)) ||
235 isModOrRefSet(AA.getModRefInfo(C2, C1)))
240 for (iterator I = begin(), E = end(); I != E; ++I)
241 if (isModOrRefSet(AA.getModRefInfo(
242 Inst, MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo()))))
248 void AliasSetTracker::clear() {
249 // Delete all the PointerRec entries.
250 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
252 I->second->eraseFromList();
256 // The alias sets should all be clear now.
261 /// mergeAliasSetsForPointer - Given a pointer, merge all alias sets that may
262 /// alias the pointer. Return the unified set, or nullptr if no set that aliases
263 /// the pointer was found.
264 AliasSet *AliasSetTracker::mergeAliasSetsForPointer(const Value *Ptr,
266 const AAMDNodes &AAInfo) {
267 AliasSet *FoundSet = nullptr;
268 for (iterator I = begin(), E = end(); I != E;) {
270 if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
272 if (!FoundSet) { // If this is the first alias set ptr can go into.
273 FoundSet = &*Cur; // Remember it.
274 } else { // Otherwise, we must merge the sets.
275 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
282 bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
283 for (const AliasSet &AS : *this)
284 if (!AS.Forward && AS.aliasesUnknownInst(Inst, AA))
289 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
290 AliasSet *FoundSet = nullptr;
291 for (iterator I = begin(), E = end(); I != E;) {
293 if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
295 if (!FoundSet) // If this is the first alias set ptr can go into.
296 FoundSet = &*Cur; // Remember it.
297 else if (!Cur->Forward) // Otherwise, we must merge the sets.
298 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
303 /// getAliasSetForPointer - Return the alias set that the specified pointer
305 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
306 const AAMDNodes &AAInfo) {
307 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
310 // At this point, the AST is saturated, so we only have one active alias
311 // set. That means we already know which alias set we want to return, and
312 // just need to add the pointer to that set to keep the data structure
314 // This, of course, means that we will never need a merge here.
315 if (Entry.hasAliasSet()) {
316 Entry.updateSizeAndAAInfo(Size, AAInfo);
317 assert(Entry.getAliasSet(*this) == AliasAnyAS &&
318 "Entry in saturated AST must belong to only alias set");
320 AliasAnyAS->addPointer(*this, Entry, Size, AAInfo);
325 // Check to see if the pointer is already known.
326 if (Entry.hasAliasSet()) {
327 // If the size changed, we may need to merge several alias sets.
328 // Note that we can *not* return the result of mergeAliasSetsForPointer
329 // due to a quirk of alias analysis behavior. Since alias(undef, undef)
330 // is NoAlias, mergeAliasSetsForPointer(undef, ...) will not find the
331 // the right set for undef, even if it exists.
332 if (Entry.updateSizeAndAAInfo(Size, AAInfo))
333 mergeAliasSetsForPointer(Pointer, Size, AAInfo);
335 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
338 if (AliasSet *AS = mergeAliasSetsForPointer(Pointer, Size, AAInfo)) {
339 // Add it to the alias set it aliases.
340 AS->addPointer(*this, Entry, Size, AAInfo);
344 // Otherwise create a new alias set to hold the loaded pointer.
345 AliasSets.push_back(new AliasSet());
346 AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
347 return AliasSets.back();
350 void AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
351 addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess);
354 void AliasSetTracker::add(LoadInst *LI) {
355 if (isStrongerThanMonotonic(LI->getOrdering())) return addUnknown(LI);
358 LI->getAAMetadata(AAInfo);
360 AliasSet::AccessLattice Access = AliasSet::RefAccess;
361 const DataLayout &DL = LI->getModule()->getDataLayout();
362 AliasSet &AS = addPointer(LI->getOperand(0),
363 DL.getTypeStoreSize(LI->getType()), AAInfo, Access);
364 if (LI->isVolatile()) AS.setVolatile();
367 void AliasSetTracker::add(StoreInst *SI) {
368 if (isStrongerThanMonotonic(SI->getOrdering())) return addUnknown(SI);
371 SI->getAAMetadata(AAInfo);
373 AliasSet::AccessLattice Access = AliasSet::ModAccess;
374 const DataLayout &DL = SI->getModule()->getDataLayout();
375 Value *Val = SI->getOperand(0);
376 AliasSet &AS = addPointer(
377 SI->getOperand(1), DL.getTypeStoreSize(Val->getType()), AAInfo, Access);
378 if (SI->isVolatile()) AS.setVolatile();
381 void AliasSetTracker::add(VAArgInst *VAAI) {
383 VAAI->getAAMetadata(AAInfo);
385 addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
386 AliasSet::ModRefAccess);
389 void AliasSetTracker::add(MemSetInst *MSI) {
391 MSI->getAAMetadata(AAInfo);
395 if (ConstantInt *C = dyn_cast<ConstantInt>(MSI->getLength()))
396 Len = C->getZExtValue();
398 Len = MemoryLocation::UnknownSize;
401 addPointer(MSI->getRawDest(), Len, AAInfo, AliasSet::ModAccess);
402 if (MSI->isVolatile())
406 void AliasSetTracker::add(MemTransferInst *MTI) {
408 MTI->getAAMetadata(AAInfo);
411 if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
412 Len = C->getZExtValue();
414 Len = MemoryLocation::UnknownSize;
417 addPointer(MTI->getRawSource(), Len, AAInfo, AliasSet::RefAccess);
418 if (MTI->isVolatile())
422 addPointer(MTI->getRawDest(), Len, AAInfo, AliasSet::ModAccess);
423 if (MTI->isVolatile())
427 void AliasSetTracker::addUnknown(Instruction *Inst) {
428 if (isa<DbgInfoIntrinsic>(Inst))
429 return; // Ignore DbgInfo Intrinsics.
431 if (auto *II = dyn_cast<IntrinsicInst>(Inst)) {
432 // These intrinsics will show up as affecting memory, but they are just
434 switch (II->getIntrinsicID()) {
437 // FIXME: Add lifetime/invariant intrinsics (See: PR30807).
438 case Intrinsic::assume:
439 case Intrinsic::sideeffect:
443 if (!Inst->mayReadOrWriteMemory())
444 return; // doesn't alias anything
446 AliasSet *AS = findAliasSetForUnknownInst(Inst);
448 AS->addUnknownInst(Inst, AA);
451 AliasSets.push_back(new AliasSet());
452 AS = &AliasSets.back();
453 AS->addUnknownInst(Inst, AA);
456 void AliasSetTracker::add(Instruction *I) {
457 // Dispatch to one of the other add methods.
458 if (LoadInst *LI = dyn_cast<LoadInst>(I))
460 if (StoreInst *SI = dyn_cast<StoreInst>(I))
462 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
464 if (MemSetInst *MSI = dyn_cast<MemSetInst>(I))
466 if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(I))
468 return addUnknown(I);
471 void AliasSetTracker::add(BasicBlock &BB) {
476 void AliasSetTracker::add(const AliasSetTracker &AST) {
477 assert(&AA == &AST.AA &&
478 "Merging AliasSetTracker objects with different Alias Analyses!");
480 // Loop over all of the alias sets in AST, adding the pointers contained
481 // therein into the current alias sets. This can cause alias sets to be
482 // merged together in the current AST.
483 for (const AliasSet &AS : AST) {
485 continue; // Ignore forwarding alias sets
487 // If there are any call sites in the alias set, add them to this AST.
488 for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
489 if (auto *Inst = AS.getUnknownInst(i))
492 // Loop over all of the pointers in this alias set.
493 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
495 addPointer(ASI.getPointer(), ASI.getSize(), ASI.getAAInfo(),
496 (AliasSet::AccessLattice)AS.Access);
497 if (AS.isVolatile()) NewAS.setVolatile();
502 // deleteValue method - This method is used to remove a pointer value from the
503 // AliasSetTracker entirely. It should be used when an instruction is deleted
504 // from the program to update the AST. If you don't use this, you would have
505 // dangling pointers to deleted instructions.
507 void AliasSetTracker::deleteValue(Value *PtrVal) {
508 // First, look up the PointerRec for this pointer.
509 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
510 if (I == PointerMap.end()) return; // Noop
512 // If we found one, remove the pointer from the alias set it is in.
513 AliasSet::PointerRec *PtrValEnt = I->second;
514 AliasSet *AS = PtrValEnt->getAliasSet(*this);
516 // Unlink and delete from the list of values.
517 PtrValEnt->eraseFromList();
519 if (AS->Alias == AliasSet::SetMayAlias) {
521 TotalMayAliasSetSize--;
524 // Stop using the alias set.
530 // copyValue - This method should be used whenever a preexisting value in the
531 // program is copied or cloned, introducing a new value. Note that it is ok for
532 // clients that use this method to introduce the same value multiple times: if
533 // the tracker already knows about a value, it will ignore the request.
535 void AliasSetTracker::copyValue(Value *From, Value *To) {
536 // First, look up the PointerRec for this pointer.
537 PointerMapType::iterator I = PointerMap.find_as(From);
538 if (I == PointerMap.end())
540 assert(I->second->hasAliasSet() && "Dead entry?");
542 AliasSet::PointerRec &Entry = getEntryFor(To);
543 if (Entry.hasAliasSet()) return; // Already in the tracker!
545 // getEntryFor above may invalidate iterator \c I, so reinitialize it.
546 I = PointerMap.find_as(From);
547 // Add it to the alias set it aliases...
548 AliasSet *AS = I->second->getAliasSet(*this);
549 AS->addPointer(*this, Entry, I->second->getSize(),
550 I->second->getAAInfo(),
554 AliasSet &AliasSetTracker::mergeAllAliasSets() {
555 assert(!AliasAnyAS && (TotalMayAliasSetSize > SaturationThreshold) &&
556 "Full merge should happen once, when the saturation threshold is "
559 // Collect all alias sets, so that we can drop references with impunity
560 // without worrying about iterator invalidation.
561 std::vector<AliasSet *> ASVector;
562 ASVector.reserve(SaturationThreshold);
563 for (iterator I = begin(), E = end(); I != E; I++)
564 ASVector.push_back(&*I);
566 // Copy all instructions and pointers into a new set, and forward all other
568 AliasSets.push_back(new AliasSet());
569 AliasAnyAS = &AliasSets.back();
570 AliasAnyAS->Alias = AliasSet::SetMayAlias;
571 AliasAnyAS->Access = AliasSet::ModRefAccess;
572 AliasAnyAS->AliasAny = true;
574 for (auto Cur : ASVector) {
575 // If Cur was already forwarding, just forward to the new AS instead.
576 AliasSet *FwdTo = Cur->Forward;
578 Cur->Forward = AliasAnyAS;
579 AliasAnyAS->addRef();
580 FwdTo->dropRef(*this);
584 // Otherwise, perform the actual merge.
585 AliasAnyAS->mergeSetIn(*Cur, *this);
591 AliasSet &AliasSetTracker::addPointer(Value *P, uint64_t Size,
592 const AAMDNodes &AAInfo,
593 AliasSet::AccessLattice E) {
594 AliasSet &AS = getAliasSetForPointer(P, Size, AAInfo);
597 if (!AliasAnyAS && (TotalMayAliasSetSize > SaturationThreshold)) {
598 // The AST is now saturated. From here on, we conservatively consider all
599 // pointers to alias each-other.
600 return mergeAllAliasSets();
606 //===----------------------------------------------------------------------===//
607 // AliasSet/AliasSetTracker Printing Support
608 //===----------------------------------------------------------------------===//
610 void AliasSet::print(raw_ostream &OS) const {
611 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
612 OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
614 case NoAccess: OS << "No access "; break;
615 case RefAccess: OS << "Ref "; break;
616 case ModAccess: OS << "Mod "; break;
617 case ModRefAccess: OS << "Mod/Ref "; break;
618 default: llvm_unreachable("Bad value for Access!");
620 if (isVolatile()) OS << "[volatile] ";
622 OS << " forwarding to " << (void*)Forward;
626 for (iterator I = begin(), E = end(); I != E; ++I) {
627 if (I != begin()) OS << ", ";
628 I.getPointer()->printAsOperand(OS << "(");
629 OS << ", " << I.getSize() << ")";
632 if (!UnknownInsts.empty()) {
633 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
634 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
636 if (auto *I = getUnknownInst(i))
637 I->printAsOperand(OS);
643 void AliasSetTracker::print(raw_ostream &OS) const {
644 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
645 << PointerMap.size() << " pointer values.\n";
646 for (const AliasSet &AS : *this)
651 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
652 LLVM_DUMP_METHOD void AliasSet::dump() const { print(dbgs()); }
653 LLVM_DUMP_METHOD void AliasSetTracker::dump() const { print(dbgs()); }
656 //===----------------------------------------------------------------------===//
657 // ASTCallbackVH Class Implementation
658 //===----------------------------------------------------------------------===//
660 void AliasSetTracker::ASTCallbackVH::deleted() {
661 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
662 AST->deleteValue(getValPtr());
666 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
667 AST->copyValue(getValPtr(), V);
670 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
671 : CallbackVH(V), AST(ast) {}
673 AliasSetTracker::ASTCallbackVH &
674 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
675 return *this = ASTCallbackVH(V, AST);
678 //===----------------------------------------------------------------------===//
679 // AliasSetPrinter Pass
680 //===----------------------------------------------------------------------===//
684 class AliasSetPrinter : public FunctionPass {
685 AliasSetTracker *Tracker;
688 static char ID; // Pass identification, replacement for typeid
690 AliasSetPrinter() : FunctionPass(ID) {
691 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
694 void getAnalysisUsage(AnalysisUsage &AU) const override {
695 AU.setPreservesAll();
696 AU.addRequired<AAResultsWrapperPass>();
699 bool runOnFunction(Function &F) override {
700 auto &AAWP = getAnalysis<AAResultsWrapperPass>();
701 Tracker = new AliasSetTracker(AAWP.getAAResults());
702 errs() << "Alias sets for function '" << F.getName() << "':\n";
703 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
705 Tracker->print(errs());
711 } // end anonymous namespace
713 char AliasSetPrinter::ID = 0;
715 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
716 "Alias Set Printer", false, true)
717 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
718 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
719 "Alias Set Printer", false, true)