778 lines
		
	
	
		
			26 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			778 lines
		
	
	
		
			26 KiB
		
	
	
	
		
			C++
		
	
	
	
| //===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===//
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| //
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| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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| // See https://llvm.org/LICENSE.txt for license information.
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| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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| //
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| //===----------------------------------------------------------------------===//
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| //
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| // This file implements the AliasSetTracker and AliasSet classes.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #include "llvm/Analysis/AliasSetTracker.h"
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| #include "llvm/Analysis/AliasAnalysis.h"
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| #include "llvm/Analysis/GuardUtils.h"
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| #include "llvm/Analysis/LoopInfo.h"
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| #include "llvm/Analysis/MemoryLocation.h"
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| #include "llvm/Analysis/MemorySSA.h"
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| #include "llvm/Config/llvm-config.h"
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| #include "llvm/IR/Constants.h"
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| #include "llvm/IR/DataLayout.h"
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| #include "llvm/IR/Function.h"
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| #include "llvm/IR/InstIterator.h"
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| #include "llvm/IR/Instruction.h"
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| #include "llvm/IR/Instructions.h"
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| #include "llvm/IR/IntrinsicInst.h"
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| #include "llvm/IR/Module.h"
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| #include "llvm/IR/PatternMatch.h"
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| #include "llvm/IR/Value.h"
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| #include "llvm/InitializePasses.h"
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| #include "llvm/Pass.h"
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| #include "llvm/Support/AtomicOrdering.h"
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| #include "llvm/Support/Casting.h"
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| #include "llvm/Support/CommandLine.h"
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| #include "llvm/Support/Compiler.h"
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| #include "llvm/Support/Debug.h"
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| #include "llvm/Support/ErrorHandling.h"
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| #include "llvm/Support/raw_ostream.h"
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| #include <cassert>
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| #include <cstdint>
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| #include <vector>
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| 
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| using namespace llvm;
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| 
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| static cl::opt<unsigned>
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|     SaturationThreshold("alias-set-saturation-threshold", cl::Hidden,
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|                         cl::init(250),
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|                         cl::desc("The maximum number of pointers may-alias "
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|                                  "sets may contain before degradation"));
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| 
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| /// mergeSetIn - Merge the specified alias set into this alias set.
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| ///
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| void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
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|   assert(!AS.Forward && "Alias set is already forwarding!");
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|   assert(!Forward && "This set is a forwarding set!!");
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| 
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|   bool WasMustAlias = (Alias == SetMustAlias);
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|   // Update the alias and access types of this set...
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|   Access |= AS.Access;
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|   Alias  |= AS.Alias;
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| 
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|   if (Alias == SetMustAlias) {
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|     // Check that these two merged sets really are must aliases.  Since both
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|     // used to be must-alias sets, we can just check any pointer from each set
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|     // for aliasing.
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|     AliasAnalysis &AA = AST.getAliasAnalysis();
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|     PointerRec *L = getSomePointer();
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|     PointerRec *R = AS.getSomePointer();
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| 
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|     // If the pointers are not a must-alias pair, this set becomes a may alias.
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|     if (AA.alias(MemoryLocation(L->getValue(), L->getSize(), L->getAAInfo()),
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|                  MemoryLocation(R->getValue(), R->getSize(), R->getAAInfo())) !=
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|         MustAlias)
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|       Alias = SetMayAlias;
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|   }
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| 
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|   if (Alias == SetMayAlias) {
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|     if (WasMustAlias)
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|       AST.TotalMayAliasSetSize += size();
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|     if (AS.Alias == SetMustAlias)
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|       AST.TotalMayAliasSetSize += AS.size();
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|   }
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| 
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|   bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
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|   if (UnknownInsts.empty()) {            // Merge call sites...
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|     if (ASHadUnknownInsts) {
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|       std::swap(UnknownInsts, AS.UnknownInsts);
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|       addRef();
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|     }
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|   } else if (ASHadUnknownInsts) {
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|     UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
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|     AS.UnknownInsts.clear();
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|   }
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| 
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|   AS.Forward = this; // Forward across AS now...
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|   addRef();          // AS is now pointing to us...
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| 
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|   // Merge the list of constituent pointers...
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|   if (AS.PtrList) {
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|     SetSize += AS.size();
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|     AS.SetSize = 0;
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|     *PtrListEnd = AS.PtrList;
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|     AS.PtrList->setPrevInList(PtrListEnd);
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|     PtrListEnd = AS.PtrListEnd;
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| 
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|     AS.PtrList = nullptr;
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|     AS.PtrListEnd = &AS.PtrList;
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|     assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
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|   }
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|   if (ASHadUnknownInsts)
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|     AS.dropRef(AST);
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| }
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| 
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| void AliasSetTracker::removeAliasSet(AliasSet *AS) {
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|   if (AliasSet *Fwd = AS->Forward) {
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|     Fwd->dropRef(*this);
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|     AS->Forward = nullptr;
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|   } else // Update TotalMayAliasSetSize only if not forwarding.
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|       if (AS->Alias == AliasSet::SetMayAlias)
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|         TotalMayAliasSetSize -= AS->size();
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| 
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|   AliasSets.erase(AS);
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|   // If we've removed the saturated alias set, set saturated marker back to
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|   // nullptr and ensure this tracker is empty.
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|   if (AS == AliasAnyAS) {
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|     AliasAnyAS = nullptr;
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|     assert(AliasSets.empty() && "Tracker not empty");
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|   }
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| }
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| 
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| void AliasSet::removeFromTracker(AliasSetTracker &AST) {
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|   assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
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|   AST.removeAliasSet(this);
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| }
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| 
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| void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
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|                           LocationSize Size, const AAMDNodes &AAInfo,
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|                           bool KnownMustAlias, bool SkipSizeUpdate) {
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|   assert(!Entry.hasAliasSet() && "Entry already in set!");
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| 
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|   // Check to see if we have to downgrade to _may_ alias.
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|   if (isMustAlias())
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|     if (PointerRec *P = getSomePointer()) {
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|       if (!KnownMustAlias) {
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|         AliasAnalysis &AA = AST.getAliasAnalysis();
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|         AliasResult Result = AA.alias(
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|             MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
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|             MemoryLocation(Entry.getValue(), Size, AAInfo));
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|         if (Result != MustAlias) {
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|           Alias = SetMayAlias;
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|           AST.TotalMayAliasSetSize += size();
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|         }
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|         assert(Result != NoAlias && "Cannot be part of must set!");
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|       } else if (!SkipSizeUpdate)
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|         P->updateSizeAndAAInfo(Size, AAInfo);
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|     }
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| 
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|   Entry.setAliasSet(this);
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|   Entry.updateSizeAndAAInfo(Size, AAInfo);
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| 
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|   // Add it to the end of the list...
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|   ++SetSize;
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|   assert(*PtrListEnd == nullptr && "End of list is not null?");
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|   *PtrListEnd = &Entry;
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|   PtrListEnd = Entry.setPrevInList(PtrListEnd);
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|   assert(*PtrListEnd == nullptr && "End of list is not null?");
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|   // Entry points to alias set.
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|   addRef();
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| 
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|   if (Alias == SetMayAlias)
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|     AST.TotalMayAliasSetSize++;
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| }
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| 
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| void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
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|   if (UnknownInsts.empty())
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|     addRef();
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|   UnknownInsts.emplace_back(I);
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| 
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|   // Guards are marked as modifying memory for control flow modelling purposes,
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|   // but don't actually modify any specific memory location.
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|   using namespace PatternMatch;
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|   bool MayWriteMemory = I->mayWriteToMemory() && !isGuard(I) &&
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|     !(I->use_empty() && match(I, m_Intrinsic<Intrinsic::invariant_start>()));
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|   if (!MayWriteMemory) {
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|     Alias = SetMayAlias;
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|     Access |= RefAccess;
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|     return;
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|   }
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| 
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|   // FIXME: This should use mod/ref information to make this not suck so bad
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|   Alias = SetMayAlias;
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|   Access = ModRefAccess;
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| }
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| 
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| /// aliasesPointer - If the specified pointer "may" (or must) alias one of the
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| /// members in the set return the appropriate AliasResult. Otherwise return
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| /// NoAlias.
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| ///
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| AliasResult AliasSet::aliasesPointer(const Value *Ptr, LocationSize Size,
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|                                      const AAMDNodes &AAInfo,
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|                                      AliasAnalysis &AA) const {
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|   if (AliasAny)
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|     return MayAlias;
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| 
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|   if (Alias == SetMustAlias) {
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|     assert(UnknownInsts.empty() && "Illegal must alias set!");
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| 
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|     // If this is a set of MustAliases, only check to see if the pointer aliases
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|     // SOME value in the set.
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|     PointerRec *SomePtr = getSomePointer();
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|     assert(SomePtr && "Empty must-alias set??");
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|     return AA.alias(MemoryLocation(SomePtr->getValue(), SomePtr->getSize(),
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|                                    SomePtr->getAAInfo()),
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|                     MemoryLocation(Ptr, Size, AAInfo));
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|   }
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| 
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|   // If this is a may-alias set, we have to check all of the pointers in the set
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|   // to be sure it doesn't alias the set...
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|   for (iterator I = begin(), E = end(); I != E; ++I)
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|     if (AliasResult AR = AA.alias(
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|             MemoryLocation(Ptr, Size, AAInfo),
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|             MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
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|       return AR;
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| 
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|   // Check the unknown instructions...
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|   if (!UnknownInsts.empty()) {
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|     for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
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|       if (auto *Inst = getUnknownInst(i))
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|         if (isModOrRefSet(
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|                 AA.getModRefInfo(Inst, MemoryLocation(Ptr, Size, AAInfo))))
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|           return MayAlias;
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|   }
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| 
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|   return NoAlias;
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| }
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| 
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| bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
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|                                   AliasAnalysis &AA) const {
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| 
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|   if (AliasAny)
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|     return true;
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| 
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|   assert(Inst->mayReadOrWriteMemory() &&
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|          "Instruction must either read or write memory.");
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| 
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|   for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
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|     if (auto *UnknownInst = getUnknownInst(i)) {
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|       const auto *C1 = dyn_cast<CallBase>(UnknownInst);
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|       const auto *C2 = dyn_cast<CallBase>(Inst);
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|       if (!C1 || !C2 || isModOrRefSet(AA.getModRefInfo(C1, C2)) ||
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|           isModOrRefSet(AA.getModRefInfo(C2, C1)))
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|         return true;
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|     }
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|   }
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| 
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|   for (iterator I = begin(), E = end(); I != E; ++I)
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|     if (isModOrRefSet(AA.getModRefInfo(
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|             Inst, MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo()))))
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|       return true;
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| 
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|   return false;
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| }
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| 
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| Instruction* AliasSet::getUniqueInstruction() {
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|   if (AliasAny)
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|     // May have collapses alias set
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|     return nullptr;
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|   if (begin() != end()) {
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|     if (!UnknownInsts.empty())
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|       // Another instruction found
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|       return nullptr;
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|     if (std::next(begin()) != end())
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|       // Another instruction found
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|       return nullptr;
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|     Value *Addr = begin()->getValue();
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|     assert(!Addr->user_empty() &&
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|            "where's the instruction which added this pointer?");
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|     if (std::next(Addr->user_begin()) != Addr->user_end())
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|       // Another instruction found -- this is really restrictive
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|       // TODO: generalize!
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|       return nullptr;
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|     return cast<Instruction>(*(Addr->user_begin()));
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|   }
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|   if (1 != UnknownInsts.size())
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|     return nullptr;
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|   return cast<Instruction>(UnknownInsts[0]);
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| }
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| 
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| void AliasSetTracker::clear() {
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|   // Delete all the PointerRec entries.
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|   for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
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|        I != E; ++I)
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|     I->second->eraseFromList();
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| 
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|   PointerMap.clear();
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| 
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|   // The alias sets should all be clear now.
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|   AliasSets.clear();
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| }
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| 
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| /// mergeAliasSetsForPointer - Given a pointer, merge all alias sets that may
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| /// alias the pointer. Return the unified set, or nullptr if no set that aliases
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| /// the pointer was found. MustAliasAll is updated to true/false if the pointer
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| /// is found to MustAlias all the sets it merged.
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| AliasSet *AliasSetTracker::mergeAliasSetsForPointer(const Value *Ptr,
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|                                                     LocationSize Size,
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|                                                     const AAMDNodes &AAInfo,
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|                                                     bool &MustAliasAll) {
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|   AliasSet *FoundSet = nullptr;
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|   AliasResult AllAR = MustAlias;
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|   for (iterator I = begin(), E = end(); I != E;) {
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|     iterator Cur = I++;
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|     if (Cur->Forward)
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|       continue;
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| 
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|     AliasResult AR = Cur->aliasesPointer(Ptr, Size, AAInfo, AA);
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|     if (AR == NoAlias)
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|       continue;
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| 
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|     AllAR =
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|         AliasResult(AllAR & AR); // Possible downgrade to May/Partial, even No
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| 
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|     if (!FoundSet) {
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|       // If this is the first alias set ptr can go into, remember it.
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|       FoundSet = &*Cur;
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|     } else {
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|       // Otherwise, we must merge the sets.
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|       FoundSet->mergeSetIn(*Cur, *this);
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|     }
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|   }
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| 
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|   MustAliasAll = (AllAR == MustAlias);
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|   return FoundSet;
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| }
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| 
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| AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
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|   AliasSet *FoundSet = nullptr;
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|   for (iterator I = begin(), E = end(); I != E;) {
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|     iterator Cur = I++;
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|     if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
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|       continue;
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|     if (!FoundSet) {
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|       // If this is the first alias set ptr can go into, remember it.
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|       FoundSet = &*Cur;
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|     } else {
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|       // Otherwise, we must merge the sets.
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|       FoundSet->mergeSetIn(*Cur, *this);
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|     }
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|   }
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|   return FoundSet;
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| }
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| 
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| AliasSet &AliasSetTracker::getAliasSetFor(const MemoryLocation &MemLoc) {
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| 
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|   Value * const Pointer = const_cast<Value*>(MemLoc.Ptr);
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|   const LocationSize Size = MemLoc.Size;
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|   const AAMDNodes &AAInfo = MemLoc.AATags;
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| 
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|   AliasSet::PointerRec &Entry = getEntryFor(Pointer);
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| 
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|   if (AliasAnyAS) {
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|     // At this point, the AST is saturated, so we only have one active alias
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|     // set. That means we already know which alias set we want to return, and
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|     // just need to add the pointer to that set to keep the data structure
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|     // consistent.
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|     // This, of course, means that we will never need a merge here.
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|     if (Entry.hasAliasSet()) {
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|       Entry.updateSizeAndAAInfo(Size, AAInfo);
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|       assert(Entry.getAliasSet(*this) == AliasAnyAS &&
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|              "Entry in saturated AST must belong to only alias set");
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|     } else {
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|       AliasAnyAS->addPointer(*this, Entry, Size, AAInfo);
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|     }
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|     return *AliasAnyAS;
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|   }
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| 
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|   bool MustAliasAll = false;
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|   // Check to see if the pointer is already known.
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|   if (Entry.hasAliasSet()) {
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|     // If the size changed, we may need to merge several alias sets.
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|     // Note that we can *not* return the result of mergeAliasSetsForPointer
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|     // due to a quirk of alias analysis behavior. Since alias(undef, undef)
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|     // is NoAlias, mergeAliasSetsForPointer(undef, ...) will not find the
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|     // the right set for undef, even if it exists.
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|     if (Entry.updateSizeAndAAInfo(Size, AAInfo))
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|       mergeAliasSetsForPointer(Pointer, Size, AAInfo, MustAliasAll);
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|     // Return the set!
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|     return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
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|   }
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| 
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|   if (AliasSet *AS =
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|           mergeAliasSetsForPointer(Pointer, Size, AAInfo, MustAliasAll)) {
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|     // Add it to the alias set it aliases.
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|     AS->addPointer(*this, Entry, Size, AAInfo, MustAliasAll);
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|     return *AS;
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|   }
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| 
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|   // Otherwise create a new alias set to hold the loaded pointer.
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|   AliasSets.push_back(new AliasSet());
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|   AliasSets.back().addPointer(*this, Entry, Size, AAInfo, true);
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|   return AliasSets.back();
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| }
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| 
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| void AliasSetTracker::add(Value *Ptr, LocationSize Size,
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|                           const AAMDNodes &AAInfo) {
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|   addPointer(MemoryLocation(Ptr, Size, AAInfo), AliasSet::NoAccess);
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| }
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| 
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| void AliasSetTracker::add(LoadInst *LI) {
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|   if (isStrongerThanMonotonic(LI->getOrdering()))
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|     return addUnknown(LI);
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|   addPointer(MemoryLocation::get(LI), AliasSet::RefAccess);
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| }
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| 
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| void AliasSetTracker::add(StoreInst *SI) {
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|   if (isStrongerThanMonotonic(SI->getOrdering()))
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|     return addUnknown(SI);
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|   addPointer(MemoryLocation::get(SI), AliasSet::ModAccess);
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| }
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| 
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| void AliasSetTracker::add(VAArgInst *VAAI) {
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|   addPointer(MemoryLocation::get(VAAI), AliasSet::ModRefAccess);
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| }
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| 
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| void AliasSetTracker::add(AnyMemSetInst *MSI) {
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|   addPointer(MemoryLocation::getForDest(MSI), AliasSet::ModAccess);
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| }
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| 
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| void AliasSetTracker::add(AnyMemTransferInst *MTI) {
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|   addPointer(MemoryLocation::getForDest(MTI), AliasSet::ModAccess);
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|   addPointer(MemoryLocation::getForSource(MTI), AliasSet::RefAccess);
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| }
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| 
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| void AliasSetTracker::addUnknown(Instruction *Inst) {
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|   if (isa<DbgInfoIntrinsic>(Inst))
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|     return; // Ignore DbgInfo Intrinsics.
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| 
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|   if (auto *II = dyn_cast<IntrinsicInst>(Inst)) {
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|     // These intrinsics will show up as affecting memory, but they are just
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|     // markers.
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|     switch (II->getIntrinsicID()) {
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|     default:
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|       break;
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|       // FIXME: Add lifetime/invariant intrinsics (See: PR30807).
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|     case Intrinsic::assume:
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|     case Intrinsic::sideeffect:
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|       return;
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|     }
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|   }
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|   if (!Inst->mayReadOrWriteMemory())
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|     return; // doesn't alias anything
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| 
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|   if (AliasSet *AS = findAliasSetForUnknownInst(Inst)) {
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|     AS->addUnknownInst(Inst, AA);
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|     return;
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|   }
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|   AliasSets.push_back(new AliasSet());
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|   AliasSets.back().addUnknownInst(Inst, AA);
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| }
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| 
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| void AliasSetTracker::add(Instruction *I) {
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|   // Dispatch to one of the other add methods.
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|   if (LoadInst *LI = dyn_cast<LoadInst>(I))
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|     return add(LI);
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|   if (StoreInst *SI = dyn_cast<StoreInst>(I))
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|     return add(SI);
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|   if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
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|     return add(VAAI);
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|   if (AnyMemSetInst *MSI = dyn_cast<AnyMemSetInst>(I))
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|     return add(MSI);
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|   if (AnyMemTransferInst *MTI = dyn_cast<AnyMemTransferInst>(I))
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|     return add(MTI);
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| 
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|   // Handle all calls with known mod/ref sets genericall
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|   if (auto *Call = dyn_cast<CallBase>(I))
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|     if (Call->onlyAccessesArgMemory()) {
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|       auto getAccessFromModRef = [](ModRefInfo MRI) {
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|         if (isRefSet(MRI) && isModSet(MRI))
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|           return AliasSet::ModRefAccess;
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|         else if (isModSet(MRI))
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|           return AliasSet::ModAccess;
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|         else if (isRefSet(MRI))
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|           return AliasSet::RefAccess;
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|         else
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|           return AliasSet::NoAccess;
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|       };
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| 
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|       ModRefInfo CallMask = createModRefInfo(AA.getModRefBehavior(Call));
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| 
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|       // Some intrinsics are marked as modifying memory for control flow
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|       // modelling purposes, but don't actually modify any specific memory
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|       // location.
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|       using namespace PatternMatch;
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|       if (Call->use_empty() &&
 | |
|           match(Call, m_Intrinsic<Intrinsic::invariant_start>()))
 | |
|         CallMask = clearMod(CallMask);
 | |
| 
 | |
|       for (auto IdxArgPair : enumerate(Call->args())) {
 | |
|         int ArgIdx = IdxArgPair.index();
 | |
|         const Value *Arg = IdxArgPair.value();
 | |
|         if (!Arg->getType()->isPointerTy())
 | |
|           continue;
 | |
|         MemoryLocation ArgLoc =
 | |
|             MemoryLocation::getForArgument(Call, ArgIdx, nullptr);
 | |
|         ModRefInfo ArgMask = AA.getArgModRefInfo(Call, ArgIdx);
 | |
|         ArgMask = intersectModRef(CallMask, ArgMask);
 | |
|         if (!isNoModRef(ArgMask))
 | |
|           addPointer(ArgLoc, getAccessFromModRef(ArgMask));
 | |
|       }
 | |
|       return;
 | |
|     }
 | |
| 
 | |
|   return addUnknown(I);
 | |
| }
 | |
| 
 | |
| void AliasSetTracker::add(BasicBlock &BB) {
 | |
|   for (auto &I : BB)
 | |
|     add(&I);
 | |
| }
 | |
| 
 | |
| void AliasSetTracker::add(const AliasSetTracker &AST) {
 | |
|   assert(&AA == &AST.AA &&
 | |
|          "Merging AliasSetTracker objects with different Alias Analyses!");
 | |
| 
 | |
|   // Loop over all of the alias sets in AST, adding the pointers contained
 | |
|   // therein into the current alias sets.  This can cause alias sets to be
 | |
|   // merged together in the current AST.
 | |
|   for (const AliasSet &AS : AST) {
 | |
|     if (AS.Forward)
 | |
|       continue; // Ignore forwarding alias sets
 | |
| 
 | |
|     // If there are any call sites in the alias set, add them to this AST.
 | |
|     for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
 | |
|       if (auto *Inst = AS.getUnknownInst(i))
 | |
|         add(Inst);
 | |
| 
 | |
|     // Loop over all of the pointers in this alias set.
 | |
|     for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI)
 | |
|       addPointer(
 | |
|           MemoryLocation(ASI.getPointer(), ASI.getSize(), ASI.getAAInfo()),
 | |
|           (AliasSet::AccessLattice)AS.Access);
 | |
|   }
 | |
| }
 | |
| 
 | |
| void AliasSetTracker::addAllInstructionsInLoopUsingMSSA() {
 | |
|   assert(MSSA && L && "MSSA and L must be available");
 | |
|   for (const BasicBlock *BB : L->blocks())
 | |
|     if (auto *Accesses = MSSA->getBlockAccesses(BB))
 | |
|       for (auto &Access : *Accesses)
 | |
|         if (auto *MUD = dyn_cast<MemoryUseOrDef>(&Access))
 | |
|           add(MUD->getMemoryInst());
 | |
| }
 | |
| 
 | |
| // deleteValue method - This method is used to remove a pointer value from the
 | |
| // AliasSetTracker entirely.  It should be used when an instruction is deleted
 | |
| // from the program to update the AST.  If you don't use this, you would have
 | |
| // dangling pointers to deleted instructions.
 | |
| //
 | |
| void AliasSetTracker::deleteValue(Value *PtrVal) {
 | |
|   // First, look up the PointerRec for this pointer.
 | |
|   PointerMapType::iterator I = PointerMap.find_as(PtrVal);
 | |
|   if (I == PointerMap.end()) return;  // Noop
 | |
| 
 | |
|   // If we found one, remove the pointer from the alias set it is in.
 | |
|   AliasSet::PointerRec *PtrValEnt = I->second;
 | |
|   AliasSet *AS = PtrValEnt->getAliasSet(*this);
 | |
| 
 | |
|   // Unlink and delete from the list of values.
 | |
|   PtrValEnt->eraseFromList();
 | |
| 
 | |
|   if (AS->Alias == AliasSet::SetMayAlias) {
 | |
|     AS->SetSize--;
 | |
|     TotalMayAliasSetSize--;
 | |
|   }
 | |
| 
 | |
|   // Stop using the alias set.
 | |
|   AS->dropRef(*this);
 | |
| 
 | |
|   PointerMap.erase(I);
 | |
| }
 | |
| 
 | |
| // copyValue - This method should be used whenever a preexisting value in the
 | |
| // program is copied or cloned, introducing a new value.  Note that it is ok for
 | |
| // clients that use this method to introduce the same value multiple times: if
 | |
| // the tracker already knows about a value, it will ignore the request.
 | |
| //
 | |
| void AliasSetTracker::copyValue(Value *From, Value *To) {
 | |
|   // First, look up the PointerRec for this pointer.
 | |
|   PointerMapType::iterator I = PointerMap.find_as(From);
 | |
|   if (I == PointerMap.end())
 | |
|     return;  // Noop
 | |
|   assert(I->second->hasAliasSet() && "Dead entry?");
 | |
| 
 | |
|   AliasSet::PointerRec &Entry = getEntryFor(To);
 | |
|   if (Entry.hasAliasSet()) return;    // Already in the tracker!
 | |
| 
 | |
|   // getEntryFor above may invalidate iterator \c I, so reinitialize it.
 | |
|   I = PointerMap.find_as(From);
 | |
|   // Add it to the alias set it aliases...
 | |
|   AliasSet *AS = I->second->getAliasSet(*this);
 | |
|   AS->addPointer(*this, Entry, I->second->getSize(), I->second->getAAInfo(),
 | |
|                  true, true);
 | |
| }
 | |
| 
 | |
| AliasSet &AliasSetTracker::mergeAllAliasSets() {
 | |
|   assert(!AliasAnyAS && (TotalMayAliasSetSize > SaturationThreshold) &&
 | |
|          "Full merge should happen once, when the saturation threshold is "
 | |
|          "reached");
 | |
| 
 | |
|   // Collect all alias sets, so that we can drop references with impunity
 | |
|   // without worrying about iterator invalidation.
 | |
|   std::vector<AliasSet *> ASVector;
 | |
|   ASVector.reserve(SaturationThreshold);
 | |
|   for (iterator I = begin(), E = end(); I != E; I++)
 | |
|     ASVector.push_back(&*I);
 | |
| 
 | |
|   // Copy all instructions and pointers into a new set, and forward all other
 | |
|   // sets to it.
 | |
|   AliasSets.push_back(new AliasSet());
 | |
|   AliasAnyAS = &AliasSets.back();
 | |
|   AliasAnyAS->Alias = AliasSet::SetMayAlias;
 | |
|   AliasAnyAS->Access = AliasSet::ModRefAccess;
 | |
|   AliasAnyAS->AliasAny = true;
 | |
| 
 | |
|   for (auto Cur : ASVector) {
 | |
|     // If Cur was already forwarding, just forward to the new AS instead.
 | |
|     AliasSet *FwdTo = Cur->Forward;
 | |
|     if (FwdTo) {
 | |
|       Cur->Forward = AliasAnyAS;
 | |
|       AliasAnyAS->addRef();
 | |
|       FwdTo->dropRef(*this);
 | |
|       continue;
 | |
|     }
 | |
| 
 | |
|     // Otherwise, perform the actual merge.
 | |
|     AliasAnyAS->mergeSetIn(*Cur, *this);
 | |
|   }
 | |
| 
 | |
|   return *AliasAnyAS;
 | |
| }
 | |
| 
 | |
| AliasSet &AliasSetTracker::addPointer(MemoryLocation Loc,
 | |
|                                       AliasSet::AccessLattice E) {
 | |
|   AliasSet &AS = getAliasSetFor(Loc);
 | |
|   AS.Access |= E;
 | |
| 
 | |
|   if (!AliasAnyAS && (TotalMayAliasSetSize > SaturationThreshold)) {
 | |
|     // The AST is now saturated. From here on, we conservatively consider all
 | |
|     // pointers to alias each-other.
 | |
|     return mergeAllAliasSets();
 | |
|   }
 | |
| 
 | |
|   return AS;
 | |
| }
 | |
| 
 | |
| //===----------------------------------------------------------------------===//
 | |
| //               AliasSet/AliasSetTracker Printing Support
 | |
| //===----------------------------------------------------------------------===//
 | |
| 
 | |
| void AliasSet::print(raw_ostream &OS) const {
 | |
|   OS << "  AliasSet[" << (const void*)this << ", " << RefCount << "] ";
 | |
|   OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
 | |
|   switch (Access) {
 | |
|   case NoAccess:     OS << "No access "; break;
 | |
|   case RefAccess:    OS << "Ref       "; break;
 | |
|   case ModAccess:    OS << "Mod       "; break;
 | |
|   case ModRefAccess: OS << "Mod/Ref   "; break;
 | |
|   default: llvm_unreachable("Bad value for Access!");
 | |
|   }
 | |
|   if (Forward)
 | |
|     OS << " forwarding to " << (void*)Forward;
 | |
| 
 | |
|   if (!empty()) {
 | |
|     OS << "Pointers: ";
 | |
|     for (iterator I = begin(), E = end(); I != E; ++I) {
 | |
|       if (I != begin()) OS << ", ";
 | |
|       I.getPointer()->printAsOperand(OS << "(");
 | |
|       if (I.getSize() == LocationSize::unknown())
 | |
|         OS << ", unknown)";
 | |
|       else
 | |
|         OS << ", " << I.getSize() << ")";
 | |
|     }
 | |
|   }
 | |
|   if (!UnknownInsts.empty()) {
 | |
|     OS << "\n    " << UnknownInsts.size() << " Unknown instructions: ";
 | |
|     for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
 | |
|       if (i) OS << ", ";
 | |
|       if (auto *I = getUnknownInst(i)) {
 | |
|         if (I->hasName())
 | |
|           I->printAsOperand(OS);
 | |
|         else
 | |
|           I->print(OS);
 | |
|       }
 | |
|     }
 | |
|   }
 | |
|   OS << "\n";
 | |
| }
 | |
| 
 | |
| void AliasSetTracker::print(raw_ostream &OS) const {
 | |
|   OS << "Alias Set Tracker: " << AliasSets.size();
 | |
|   if (AliasAnyAS)
 | |
|     OS << " (Saturated)";
 | |
|   OS << " alias sets for " << PointerMap.size() << " pointer values.\n";
 | |
|   for (const AliasSet &AS : *this)
 | |
|     AS.print(OS);
 | |
|   OS << "\n";
 | |
| }
 | |
| 
 | |
| #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 | |
| LLVM_DUMP_METHOD void AliasSet::dump() const { print(dbgs()); }
 | |
| LLVM_DUMP_METHOD void AliasSetTracker::dump() const { print(dbgs()); }
 | |
| #endif
 | |
| 
 | |
| //===----------------------------------------------------------------------===//
 | |
| //                     ASTCallbackVH Class Implementation
 | |
| //===----------------------------------------------------------------------===//
 | |
| 
 | |
| void AliasSetTracker::ASTCallbackVH::deleted() {
 | |
|   assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
 | |
|   AST->deleteValue(getValPtr());
 | |
|   // this now dangles!
 | |
| }
 | |
| 
 | |
| void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
 | |
|   AST->copyValue(getValPtr(), V);
 | |
| }
 | |
| 
 | |
| AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
 | |
|   : CallbackVH(V), AST(ast) {}
 | |
| 
 | |
| AliasSetTracker::ASTCallbackVH &
 | |
| AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
 | |
|   return *this = ASTCallbackVH(V, AST);
 | |
| }
 | |
| 
 | |
| //===----------------------------------------------------------------------===//
 | |
| //                            AliasSetPrinter Pass
 | |
| //===----------------------------------------------------------------------===//
 | |
| 
 | |
| namespace {
 | |
| 
 | |
|   class AliasSetPrinter : public FunctionPass {
 | |
|     AliasSetTracker *Tracker;
 | |
| 
 | |
|   public:
 | |
|     static char ID; // Pass identification, replacement for typeid
 | |
| 
 | |
|     AliasSetPrinter() : FunctionPass(ID) {
 | |
|       initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
 | |
|     }
 | |
| 
 | |
|     void getAnalysisUsage(AnalysisUsage &AU) const override {
 | |
|       AU.setPreservesAll();
 | |
|       AU.addRequired<AAResultsWrapperPass>();
 | |
|     }
 | |
| 
 | |
|     bool runOnFunction(Function &F) override {
 | |
|       auto &AAWP = getAnalysis<AAResultsWrapperPass>();
 | |
|       Tracker = new AliasSetTracker(AAWP.getAAResults());
 | |
|       errs() << "Alias sets for function '" << F.getName() << "':\n";
 | |
|       for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
 | |
|         Tracker->add(&*I);
 | |
|       Tracker->print(errs());
 | |
|       delete Tracker;
 | |
|       return false;
 | |
|     }
 | |
|   };
 | |
| 
 | |
| } // end anonymous namespace
 | |
| 
 | |
| char AliasSetPrinter::ID = 0;
 | |
| 
 | |
| INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
 | |
|                 "Alias Set Printer", false, true)
 | |
| INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 | |
| INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
 | |
|                 "Alias Set Printer", false, true)
 |