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9971ac4a36
a union-find based algorithm, is significantly faster, and is more general. It will also scale to handle call instructions correctly, which is a nice added bonus. This includes a new pass -print-alias-sets which can be used to show how alias sets are formed for a particular analysis. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5619 91177308-0d34-0410-b5e6-96231b3b80d8
266 lines
8.3 KiB
C++
266 lines
8.3 KiB
C++
//===- llvm/Analysis/AliasSetTracker.h - Build Alias Sets -------*- C++ -*-===//
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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/Support/CallSite.h"
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#include "Support/iterator"
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#include "Support/hash_map"
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#include "Support/ilist"
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class AliasAnalysis;
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class LoadInst;
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class StoreInst;
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class AliasSetTracker;
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class AliasSet;
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class AliasSet {
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friend class AliasSetTracker;
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struct PointerRec;
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typedef std::pair<Value* const, PointerRec> HashNodePair;
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class PointerRec {
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HashNodePair *NextInList;
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AliasSet *AS;
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public:
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PointerRec() : NextInList(0), AS(0) {}
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HashNodePair *getNext() const { return NextInList; }
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bool hasAliasSet() const { return AS != 0; }
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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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if (--OldAS->RefCount == 0)
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OldAS->removeFromTracker(AST);
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AS->RefCount++;
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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 == 0 && "Already have an alias set!");
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AS = as;
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}
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void setTail(HashNodePair *T) {
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assert(NextInList == 0 && "Already have tail!");
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NextInList = T;
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}
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};
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HashNodePair *PtrListHead, *PtrListTail; // Singly linked list of nodes
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AliasSet *Forward; // Forwarding pointer
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AliasSet *Next, *Prev; // Doubly linked list of AliasSets
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std::vector<CallSite> CallSites; // All calls & invokes in this node
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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 : 29;
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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 neccesary.
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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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/// Define an iterator for alias sets... this is just a forward iterator.
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class iterator : public forward_iterator<Value*, ptrdiff_t> {
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HashNodePair *CurNode;
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public:
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iterator(HashNodePair *CN = 0) : 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->first;
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}
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value_type operator->() const { return operator*(); }
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iterator& operator++() { // Preincrement
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assert(CurNode && "Advancing past AliasSet.end()!");
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CurNode = CurNode->second.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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friend class ilist_traits<AliasSet>;
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AliasSet *getPrev() const { return Prev; }
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AliasSet *getNext() const { return Next; }
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void setPrev(AliasSet *P) { Prev = P; }
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void setNext(AliasSet *N) { Next = N; }
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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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/// mergeSetIn - Merge the specified alias set into this alias set...
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///
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void mergeSetIn(AliasSet &AS);
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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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iterator begin() const { return iterator(PtrListHead); }
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iterator end() const { return iterator(); }
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void print(std::ostream &OS) const;
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void dump() const;
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private:
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// Can only be created by AliasSetTracker
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AliasSet() : PtrListHead(0), PtrListTail(0), Forward(0), RefCount(0),
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AccessTy(NoModRef), AliasTy(MustAlias) {
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}
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Value *getSomePointer() const {
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return PtrListHead ? PtrListHead->first : 0;
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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->RefCount++;
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if (--Forward->RefCount == 0)
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Forward->removeFromTracker(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, HashNodePair &Entry);
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void addCallSite(CallSite CS);
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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, AliasAnalysis &AA) const;
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bool aliasesCallSite(CallSite CS, AliasAnalysis &AA) const;
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};
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inline std::ostream& operator<<(std::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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AliasAnalysis &AA;
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ilist<AliasSet> AliasSets;
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// Map from pointers to their node
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hash_map<Value*, AliasSet::PointerRec> 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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AliasSetTracker(AliasAnalysis &aa) : AA(aa) {}
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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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void add(LoadInst *LI);
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void add(StoreInst *SI);
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void add(CallSite CS); // Call/Invoke instructions
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void add(CallInst *CI) { add(CallSite(CI)); }
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void add(InvokeInst *II) { add(CallSite(II)); }
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void add(Instruction *I); // Dispatch to one of the other add methods...
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/// getAliasSets - Return the alias sets that are active.
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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...
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AliasSet &getAliasSetForPointer(Value *P);
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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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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(std::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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AliasSet::HashNodePair &getEntryFor(Value *V) {
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// Standard operator[], except that it returns the whole pair, not just
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// ->second.
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return *PointerMap.insert(AliasSet::HashNodePair(V,
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AliasSet::PointerRec())).first;
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}
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void addPointer(Value *P, AliasSet::AccessType E) {
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AliasSet &AS = getAliasSetForPointer(P);
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AS.AccessTy |= E;
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}
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AliasSet *findAliasSetForPointer(const Value *Ptr);
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AliasSet *findAliasSetForCallSite(CallSite CS);
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};
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inline std::ostream& operator<<(std::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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#endif
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