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In order to enable the preservation of noalias function parameter information after inlining, and the representation of block-level __restrict__ pointer information (etc.), additional kinds of aliasing metadata will be introduced. This metadata needs to be carried around in AliasAnalysis::Location objects (and MMOs at the SDAG level), and so we need to generalize the current scheme (which is hard-coded to just one TBAA MDNode*). This commit introduces only the necessary refactoring to allow for the introduction of other aliasing metadata types, but does not actually introduce any (that will come in a follow-up commit). What it does introduce is a new AAMDNodes structure to hold all of the aliasing metadata nodes associated with a particular memory-accessing instruction, and uses that structure instead of the raw MDNode* in AliasAnalysis::Location, etc. No functionality change intended. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213859 91177308-0d34-0410-b5e6-96231b3b80d8
440 lines
15 KiB
C++
440 lines
15 KiB
C++
//===- llvm/Analysis/AliasSetTracker.h - Build Alias Sets -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines two classes: AliasSetTracker and AliasSet. These interface
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// are used to classify a collection of pointer references into a maximal number
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// of disjoint sets. Each AliasSet object constructed by the AliasSetTracker
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// object refers to memory disjoint from the other sets.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_ALIASSETTRACKER_H
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#define LLVM_ANALYSIS_ALIASSETTRACKER_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/ilist.h"
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#include "llvm/ADT/ilist_node.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/IR/ValueHandle.h"
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#include <vector>
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namespace llvm {
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class AliasAnalysis;
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class LoadInst;
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class StoreInst;
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class VAArgInst;
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class AliasSetTracker;
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class AliasSet;
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class AliasSet : public ilist_node<AliasSet> {
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friend class AliasSetTracker;
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class PointerRec {
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Value *Val; // The pointer this record corresponds to.
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PointerRec **PrevInList, *NextInList;
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AliasSet *AS;
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uint64_t Size;
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AAMDNodes AAInfo;
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public:
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PointerRec(Value *V)
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: Val(V), PrevInList(nullptr), NextInList(nullptr), AS(nullptr), Size(0),
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AAInfo(DenseMapInfo<AAMDNodes>::getEmptyKey()) {}
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Value *getValue() const { return Val; }
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PointerRec *getNext() const { return NextInList; }
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bool hasAliasSet() const { return AS != nullptr; }
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PointerRec** setPrevInList(PointerRec **PIL) {
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PrevInList = PIL;
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return &NextInList;
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}
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void updateSizeAndAAInfo(uint64_t NewSize, const AAMDNodes &NewAAInfo) {
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if (NewSize > Size) Size = NewSize;
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if (AAInfo == DenseMapInfo<AAMDNodes>::getEmptyKey())
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// We don't have a AAInfo yet. Set it to NewAAInfo.
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AAInfo = NewAAInfo;
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else if (AAInfo != NewAAInfo)
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// NewAAInfo conflicts with AAInfo.
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AAInfo = DenseMapInfo<AAMDNodes>::getTombstoneKey();
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}
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uint64_t getSize() const { return Size; }
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/// getAAInfo - Return the AAInfo, or null if there is no
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/// information or conflicting information.
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AAMDNodes getAAInfo() const {
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// If we have missing or conflicting AAInfo, return null.
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if (AAInfo == DenseMapInfo<AAMDNodes>::getEmptyKey() ||
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AAInfo == DenseMapInfo<AAMDNodes>::getTombstoneKey())
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return AAMDNodes();
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return AAInfo;
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}
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AliasSet *getAliasSet(AliasSetTracker &AST) {
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assert(AS && "No AliasSet yet!");
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if (AS->Forward) {
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AliasSet *OldAS = AS;
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AS = OldAS->getForwardedTarget(AST);
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AS->addRef();
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OldAS->dropRef(AST);
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}
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return AS;
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}
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void setAliasSet(AliasSet *as) {
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assert(!AS && "Already have an alias set!");
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AS = as;
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}
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void eraseFromList() {
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if (NextInList) NextInList->PrevInList = PrevInList;
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*PrevInList = NextInList;
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if (AS->PtrListEnd == &NextInList) {
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AS->PtrListEnd = PrevInList;
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assert(*AS->PtrListEnd == nullptr && "List not terminated right!");
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}
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delete this;
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}
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};
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PointerRec *PtrList, **PtrListEnd; // Doubly linked list of nodes.
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AliasSet *Forward; // Forwarding pointer.
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// All instructions without a specific address in this alias set.
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std::vector<AssertingVH<Instruction> > UnknownInsts;
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// RefCount - Number of nodes pointing to this AliasSet plus the number of
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// AliasSets forwarding to it.
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unsigned RefCount : 28;
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/// AccessType - Keep track of whether this alias set merely refers to the
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/// locations of memory, whether it modifies the memory, or whether it does
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/// both. The lattice goes from "NoModRef" to either Refs or Mods, then to
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/// ModRef as necessary.
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///
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enum AccessType {
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NoModRef = 0, Refs = 1, // Ref = bit 1
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Mods = 2, ModRef = 3 // Mod = bit 2
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};
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unsigned AccessTy : 2;
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/// AliasType - Keep track the relationships between the pointers in the set.
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/// Lattice goes from MustAlias to MayAlias.
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///
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enum AliasType {
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MustAlias = 0, MayAlias = 1
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};
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unsigned AliasTy : 1;
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// Volatile - True if this alias set contains volatile loads or stores.
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bool Volatile : 1;
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void addRef() { ++RefCount; }
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void dropRef(AliasSetTracker &AST) {
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assert(RefCount >= 1 && "Invalid reference count detected!");
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if (--RefCount == 0)
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removeFromTracker(AST);
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}
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Instruction *getUnknownInst(unsigned i) const {
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assert(i < UnknownInsts.size());
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return UnknownInsts[i];
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}
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public:
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/// Accessors...
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bool isRef() const { return AccessTy & Refs; }
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bool isMod() const { return AccessTy & Mods; }
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bool isMustAlias() const { return AliasTy == MustAlias; }
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bool isMayAlias() const { return AliasTy == MayAlias; }
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// isVolatile - Return true if this alias set contains volatile loads or
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// stores.
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bool isVolatile() const { return Volatile; }
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/// isForwardingAliasSet - Return true if this alias set should be ignored as
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/// part of the AliasSetTracker object.
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bool isForwardingAliasSet() const { return Forward; }
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/// mergeSetIn - Merge the specified alias set into this alias set...
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///
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void mergeSetIn(AliasSet &AS, AliasSetTracker &AST);
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// Alias Set iteration - Allow access to all of the pointer which are part of
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// this alias set...
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class iterator;
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iterator begin() const { return iterator(PtrList); }
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iterator end() const { return iterator(); }
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bool empty() const { return PtrList == nullptr; }
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void print(raw_ostream &OS) const;
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void dump() const;
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/// Define an iterator for alias sets... this is just a forward iterator.
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class iterator : public std::iterator<std::forward_iterator_tag,
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PointerRec, ptrdiff_t> {
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PointerRec *CurNode;
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public:
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explicit iterator(PointerRec *CN = nullptr) : CurNode(CN) {}
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bool operator==(const iterator& x) const {
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return CurNode == x.CurNode;
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}
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bool operator!=(const iterator& x) const { return !operator==(x); }
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const iterator &operator=(const iterator &I) {
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CurNode = I.CurNode;
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return *this;
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}
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value_type &operator*() const {
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assert(CurNode && "Dereferencing AliasSet.end()!");
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return *CurNode;
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}
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value_type *operator->() const { return &operator*(); }
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Value *getPointer() const { return CurNode->getValue(); }
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uint64_t getSize() const { return CurNode->getSize(); }
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AAMDNodes getAAInfo() const { return CurNode->getAAInfo(); }
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iterator& operator++() { // Preincrement
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assert(CurNode && "Advancing past AliasSet.end()!");
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CurNode = CurNode->getNext();
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return *this;
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}
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iterator operator++(int) { // Postincrement
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iterator tmp = *this; ++*this; return tmp;
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}
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};
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private:
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// Can only be created by AliasSetTracker. Also, ilist creates one
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// to serve as a sentinel.
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friend struct ilist_sentinel_traits<AliasSet>;
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AliasSet()
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: PtrList(nullptr), PtrListEnd(&PtrList), Forward(nullptr), RefCount(0),
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AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) {
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}
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AliasSet(const AliasSet &AS) LLVM_DELETED_FUNCTION;
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void operator=(const AliasSet &AS) LLVM_DELETED_FUNCTION;
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PointerRec *getSomePointer() const {
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return PtrList;
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}
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/// getForwardedTarget - Return the real alias set this represents. If this
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/// has been merged with another set and is forwarding, return the ultimate
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/// destination set. This also implements the union-find collapsing as well.
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AliasSet *getForwardedTarget(AliasSetTracker &AST) {
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if (!Forward) return this;
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AliasSet *Dest = Forward->getForwardedTarget(AST);
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if (Dest != Forward) {
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Dest->addRef();
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Forward->dropRef(AST);
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Forward = Dest;
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}
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return Dest;
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}
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void removeFromTracker(AliasSetTracker &AST);
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void addPointer(AliasSetTracker &AST, PointerRec &Entry, uint64_t Size,
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const AAMDNodes &AAInfo,
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bool KnownMustAlias = false);
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void addUnknownInst(Instruction *I, AliasAnalysis &AA);
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void removeUnknownInst(Instruction *I) {
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for (size_t i = 0, e = UnknownInsts.size(); i != e; ++i)
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if (UnknownInsts[i] == I) {
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UnknownInsts[i] = UnknownInsts.back();
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UnknownInsts.pop_back();
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--i; --e; // Revisit the moved entry.
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}
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}
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void setVolatile() { Volatile = true; }
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public:
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/// aliasesPointer - Return true if the specified pointer "may" (or must)
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/// alias one of the members in the set.
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///
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bool aliasesPointer(const Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo,
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AliasAnalysis &AA) const;
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bool aliasesUnknownInst(Instruction *Inst, AliasAnalysis &AA) const;
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};
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inline raw_ostream& operator<<(raw_ostream &OS, const AliasSet &AS) {
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AS.print(OS);
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return OS;
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}
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class AliasSetTracker {
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/// CallbackVH - A CallbackVH to arrange for AliasSetTracker to be
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/// notified whenever a Value is deleted.
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class ASTCallbackVH : public CallbackVH {
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AliasSetTracker *AST;
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void deleted() override;
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void allUsesReplacedWith(Value *) override;
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public:
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ASTCallbackVH(Value *V, AliasSetTracker *AST = nullptr);
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ASTCallbackVH &operator=(Value *V);
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};
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/// ASTCallbackVHDenseMapInfo - Traits to tell DenseMap that tell us how to
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/// compare and hash the value handle.
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struct ASTCallbackVHDenseMapInfo : public DenseMapInfo<Value *> {};
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AliasAnalysis &AA;
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ilist<AliasSet> AliasSets;
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typedef DenseMap<ASTCallbackVH, AliasSet::PointerRec*,
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ASTCallbackVHDenseMapInfo>
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PointerMapType;
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// Map from pointers to their node
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PointerMapType PointerMap;
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public:
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/// AliasSetTracker ctor - Create an empty collection of AliasSets, and use
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/// the specified alias analysis object to disambiguate load and store
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/// addresses.
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explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {}
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~AliasSetTracker() { clear(); }
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/// add methods - These methods are used to add different types of
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/// instructions to the alias sets. Adding a new instruction can result in
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/// one of three actions happening:
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///
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/// 1. If the instruction doesn't alias any other sets, create a new set.
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/// 2. If the instruction aliases exactly one set, add it to the set
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/// 3. If the instruction aliases multiple sets, merge the sets, and add
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/// the instruction to the result.
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///
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/// These methods return true if inserting the instruction resulted in the
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/// addition of a new alias set (i.e., the pointer did not alias anything).
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///
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bool add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo); // Add a loc.
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bool add(LoadInst *LI);
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bool add(StoreInst *SI);
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bool add(VAArgInst *VAAI);
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bool add(Instruction *I); // Dispatch to one of the other add methods...
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void add(BasicBlock &BB); // Add all instructions in basic block
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void add(const AliasSetTracker &AST); // Add alias relations from another AST
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bool addUnknown(Instruction *I);
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/// remove methods - These methods are used to remove all entries that might
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/// be aliased by the specified instruction. These methods return true if any
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/// alias sets were eliminated.
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// Remove a location
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bool remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo);
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bool remove(LoadInst *LI);
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bool remove(StoreInst *SI);
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bool remove(VAArgInst *VAAI);
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bool remove(Instruction *I);
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void remove(AliasSet &AS);
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bool removeUnknown(Instruction *I);
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void clear();
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/// getAliasSets - Return the alias sets that are active.
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///
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const ilist<AliasSet> &getAliasSets() const { return AliasSets; }
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/// getAliasSetForPointer - Return the alias set that the specified pointer
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/// lives in. If the New argument is non-null, this method sets the value to
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/// true if a new alias set is created to contain the pointer (because the
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/// pointer didn't alias anything).
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AliasSet &getAliasSetForPointer(Value *P, uint64_t Size,
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const AAMDNodes &AAInfo,
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bool *New = nullptr);
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/// getAliasSetForPointerIfExists - Return the alias set containing the
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/// location specified if one exists, otherwise return null.
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AliasSet *getAliasSetForPointerIfExists(Value *P, uint64_t Size,
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const AAMDNodes &AAInfo) {
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return findAliasSetForPointer(P, Size, AAInfo);
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}
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/// containsPointer - Return true if the specified location is represented by
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/// this alias set, false otherwise. This does not modify the AST object or
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/// alias sets.
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bool containsPointer(Value *P, uint64_t Size, const AAMDNodes &AAInfo) const;
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/// getAliasAnalysis - Return the underlying alias analysis object used by
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/// this tracker.
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AliasAnalysis &getAliasAnalysis() const { return AA; }
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/// deleteValue method - This method is used to remove a pointer value from
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/// the AliasSetTracker entirely. It should be used when an instruction is
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/// deleted from the program to update the AST. If you don't use this, you
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/// would have dangling pointers to deleted instructions.
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///
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void deleteValue(Value *PtrVal);
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/// copyValue - This method should be used whenever a preexisting value in the
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/// program is copied or cloned, introducing a new value. Note that it is ok
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/// for clients that use this method to introduce the same value multiple
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/// times: if the tracker already knows about a value, it will ignore the
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/// request.
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///
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void copyValue(Value *From, Value *To);
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typedef ilist<AliasSet>::iterator iterator;
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typedef ilist<AliasSet>::const_iterator const_iterator;
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const_iterator begin() const { return AliasSets.begin(); }
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const_iterator end() const { return AliasSets.end(); }
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iterator begin() { return AliasSets.begin(); }
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iterator end() { return AliasSets.end(); }
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void print(raw_ostream &OS) const;
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void dump() const;
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private:
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friend class AliasSet;
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void removeAliasSet(AliasSet *AS);
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// getEntryFor - Just like operator[] on the map, except that it creates an
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// entry for the pointer if it doesn't already exist.
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AliasSet::PointerRec &getEntryFor(Value *V) {
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AliasSet::PointerRec *&Entry = PointerMap[ASTCallbackVH(V, this)];
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if (!Entry)
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Entry = new AliasSet::PointerRec(V);
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return *Entry;
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}
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AliasSet &addPointer(Value *P, uint64_t Size, const AAMDNodes &AAInfo,
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AliasSet::AccessType E,
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bool &NewSet) {
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NewSet = false;
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AliasSet &AS = getAliasSetForPointer(P, Size, AAInfo, &NewSet);
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AS.AccessTy |= E;
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return AS;
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}
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AliasSet *findAliasSetForPointer(const Value *Ptr, uint64_t Size,
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const AAMDNodes &AAInfo);
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AliasSet *findAliasSetForUnknownInst(Instruction *Inst);
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};
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inline raw_ostream& operator<<(raw_ostream &OS, const AliasSetTracker &AST) {
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AST.print(OS);
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return OS;
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}
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} // End llvm namespace
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#endif
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