1 //===- llvm/Analysis/AliasSetTracker.h - Build Alias Sets -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines two classes: AliasSetTracker and AliasSet. These interface
11 // are used to classify a collection of pointer references into a maximal number
12 // of disjoint sets. Each AliasSet object constructed by the AliasSetTracker
13 // object refers to memory disjoint from the other sets.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_ANALYSIS_ALIASSETTRACKER_H
18 #define LLVM_ANALYSIS_ALIASSETTRACKER_H
20 #include "llvm/Support/CallSite.h"
21 #include "llvm/Support/ValueHandle.h"
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/ADT/ilist.h"
24 #include "llvm/ADT/ilist_node.h"
33 class AliasSetTracker;
36 class AliasSet : public ilist_node<AliasSet> {
37 friend class AliasSetTracker;
40 Value *Val; // The pointer this record corresponds to.
41 PointerRec **PrevInList, *NextInList;
46 : Val(V), PrevInList(0), NextInList(0), AS(0), Size(0) {}
48 Value *getValue() const { return Val; }
50 PointerRec *getNext() const { return NextInList; }
51 bool hasAliasSet() const { return AS != 0; }
53 PointerRec** setPrevInList(PointerRec **PIL) {
58 void updateSize(unsigned NewSize) {
59 if (NewSize > Size) Size = NewSize;
62 unsigned getSize() const { return Size; }
64 AliasSet *getAliasSet(AliasSetTracker &AST) {
65 assert(AS && "No AliasSet yet!");
68 AS = OldAS->getForwardedTarget(AST);
75 void setAliasSet(AliasSet *as) {
76 assert(AS == 0 && "Already have an alias set!");
80 void eraseFromList() {
81 if (NextInList) NextInList->PrevInList = PrevInList;
82 *PrevInList = NextInList;
83 if (AS->PtrListEnd == &NextInList) {
84 AS->PtrListEnd = PrevInList;
85 assert(*AS->PtrListEnd == 0 && "List not terminated right!");
91 PointerRec *PtrList, **PtrListEnd; // Doubly linked list of nodes.
92 AliasSet *Forward; // Forwarding pointer.
93 AliasSet *Next, *Prev; // Doubly linked list of AliasSets.
95 // All calls & invokes in this alias set.
96 std::vector<AssertingVH<Instruction> > CallSites;
98 // RefCount - Number of nodes pointing to this AliasSet plus the number of
99 // AliasSets forwarding to it.
100 unsigned RefCount : 28;
102 /// AccessType - Keep track of whether this alias set merely refers to the
103 /// locations of memory, whether it modifies the memory, or whether it does
104 /// both. The lattice goes from "NoModRef" to either Refs or Mods, then to
105 /// ModRef as necessary.
108 NoModRef = 0, Refs = 1, // Ref = bit 1
109 Mods = 2, ModRef = 3 // Mod = bit 2
111 unsigned AccessTy : 2;
113 /// AliasType - Keep track the relationships between the pointers in the set.
114 /// Lattice goes from MustAlias to MayAlias.
117 MustAlias = 0, MayAlias = 1
119 unsigned AliasTy : 1;
121 // Volatile - True if this alias set contains volatile loads or stores.
124 void addRef() { ++RefCount; }
125 void dropRef(AliasSetTracker &AST) {
126 assert(RefCount >= 1 && "Invalid reference count detected!");
128 removeFromTracker(AST);
131 CallSite getCallSite(unsigned i) const {
132 assert(i < CallSites.size());
133 return CallSite(CallSites[i]);
138 bool isRef() const { return AccessTy & Refs; }
139 bool isMod() const { return AccessTy & Mods; }
140 bool isMustAlias() const { return AliasTy == MustAlias; }
141 bool isMayAlias() const { return AliasTy == MayAlias; }
143 // isVolatile - Return true if this alias set contains volatile loads or
145 bool isVolatile() const { return Volatile; }
147 /// isForwardingAliasSet - Return true if this alias set should be ignored as
148 /// part of the AliasSetTracker object.
149 bool isForwardingAliasSet() const { return Forward; }
151 /// mergeSetIn - Merge the specified alias set into this alias set...
153 void mergeSetIn(AliasSet &AS, AliasSetTracker &AST);
155 // Alias Set iteration - Allow access to all of the pointer which are part of
158 iterator begin() const { return iterator(PtrList); }
159 iterator end() const { return iterator(); }
160 bool empty() const { return PtrList == 0; }
162 void print(raw_ostream &OS) const;
165 /// Define an iterator for alias sets... this is just a forward iterator.
166 class iterator : public std::iterator<std::forward_iterator_tag,
167 PointerRec, ptrdiff_t> {
170 explicit iterator(PointerRec *CN = 0) : CurNode(CN) {}
172 bool operator==(const iterator& x) const {
173 return CurNode == x.CurNode;
175 bool operator!=(const iterator& x) const { return !operator==(x); }
177 const iterator &operator=(const iterator &I) {
182 value_type &operator*() const {
183 assert(CurNode && "Dereferencing AliasSet.end()!");
186 value_type *operator->() const { return &operator*(); }
188 Value *getPointer() const { return CurNode->getValue(); }
189 unsigned getSize() const { return CurNode->getSize(); }
191 iterator& operator++() { // Preincrement
192 assert(CurNode && "Advancing past AliasSet.end()!");
193 CurNode = CurNode->getNext();
196 iterator operator++(int) { // Postincrement
197 iterator tmp = *this; ++*this; return tmp;
202 // Can only be created by AliasSetTracker. Also, ilist creates one
203 // to serve as a sentinel.
204 friend struct ilist_sentinel_traits<AliasSet>;
205 AliasSet() : PtrList(0), PtrListEnd(&PtrList), Forward(0), RefCount(0),
206 AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) {
209 AliasSet(const AliasSet &AS); // do not implement
210 void operator=(const AliasSet &AS); // do not implement
212 PointerRec *getSomePointer() const {
216 /// getForwardedTarget - Return the real alias set this represents. If this
217 /// has been merged with another set and is forwarding, return the ultimate
218 /// destination set. This also implements the union-find collapsing as well.
219 AliasSet *getForwardedTarget(AliasSetTracker &AST) {
220 if (!Forward) return this;
222 AliasSet *Dest = Forward->getForwardedTarget(AST);
223 if (Dest != Forward) {
225 Forward->dropRef(AST);
231 void removeFromTracker(AliasSetTracker &AST);
233 void addPointer(AliasSetTracker &AST, PointerRec &Entry, unsigned Size,
234 bool KnownMustAlias = false);
235 void addCallSite(CallSite CS, AliasAnalysis &AA);
236 void removeCallSite(CallSite CS) {
237 for (size_t i = 0, e = CallSites.size(); i != e; ++i)
238 if (CallSites[i] == CS.getInstruction()) {
239 CallSites[i] = CallSites.back();
240 CallSites.pop_back();
243 void setVolatile() { Volatile = true; }
245 /// aliasesPointer - Return true if the specified pointer "may" (or must)
246 /// alias one of the members in the set.
248 bool aliasesPointer(const Value *Ptr, unsigned Size, AliasAnalysis &AA) const;
249 bool aliasesCallSite(CallSite CS, AliasAnalysis &AA) const;
252 inline raw_ostream& operator<<(raw_ostream &OS, const AliasSet &AS) {
258 class AliasSetTracker {
259 /// CallbackVH - A CallbackVH to arrange for AliasSetTracker to be
260 /// notified whenever a Value is deleted.
261 class ASTCallbackVH : public CallbackVH {
262 AliasSetTracker *AST;
263 virtual void deleted();
265 ASTCallbackVH(Value *V, AliasSetTracker *AST = 0);
266 ASTCallbackVH &operator=(Value *V);
268 /// ASTCallbackVHDenseMapInfo - Traits to tell DenseMap that tell us how to
269 /// compare and hash the value handle.
270 struct ASTCallbackVHDenseMapInfo : public DenseMapInfo<Value *> {};
273 ilist<AliasSet> AliasSets;
275 typedef DenseMap<ASTCallbackVH, AliasSet::PointerRec*,
276 ASTCallbackVHDenseMapInfo>
279 // Map from pointers to their node
280 PointerMapType PointerMap;
283 /// AliasSetTracker ctor - Create an empty collection of AliasSets, and use
284 /// the specified alias analysis object to disambiguate load and store
286 explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {}
287 ~AliasSetTracker() { clear(); }
289 /// add methods - These methods are used to add different types of
290 /// instructions to the alias sets. Adding a new instruction can result in
291 /// one of three actions happening:
293 /// 1. If the instruction doesn't alias any other sets, create a new set.
294 /// 2. If the instruction aliases exactly one set, add it to the set
295 /// 3. If the instruction aliases multiple sets, merge the sets, and add
296 /// the instruction to the result.
298 /// These methods return true if inserting the instruction resulted in the
299 /// addition of a new alias set (i.e., the pointer did not alias anything).
301 bool add(Value *Ptr, unsigned Size); // Add a location
302 bool add(LoadInst *LI);
303 bool add(StoreInst *SI);
304 bool add(VAArgInst *VAAI);
305 bool add(CallSite CS); // Call/Invoke instructions
306 bool add(CallInst *CI) { return add(CallSite(CI)); }
307 bool add(InvokeInst *II) { return add(CallSite(II)); }
308 bool add(Instruction *I); // Dispatch to one of the other add methods...
309 void add(BasicBlock &BB); // Add all instructions in basic block
310 void add(const AliasSetTracker &AST); // Add alias relations from another AST
312 /// remove methods - These methods are used to remove all entries that might
313 /// be aliased by the specified instruction. These methods return true if any
314 /// alias sets were eliminated.
315 bool remove(Value *Ptr, unsigned Size); // Remove a location
316 bool remove(LoadInst *LI);
317 bool remove(StoreInst *SI);
318 bool remove(VAArgInst *VAAI);
319 bool remove(CallSite CS);
320 bool remove(CallInst *CI) { return remove(CallSite(CI)); }
321 bool remove(InvokeInst *II) { return remove(CallSite(II)); }
322 bool remove(Instruction *I);
323 void remove(AliasSet &AS);
327 /// getAliasSets - Return the alias sets that are active.
329 const ilist<AliasSet> &getAliasSets() const { return AliasSets; }
331 /// getAliasSetForPointer - Return the alias set that the specified pointer
332 /// lives in. If the New argument is non-null, this method sets the value to
333 /// true if a new alias set is created to contain the pointer (because the
334 /// pointer didn't alias anything).
335 AliasSet &getAliasSetForPointer(Value *P, unsigned Size, bool *New = 0);
337 /// getAliasSetForPointerIfExists - Return the alias set containing the
338 /// location specified if one exists, otherwise return null.
339 AliasSet *getAliasSetForPointerIfExists(Value *P, unsigned Size) {
340 return findAliasSetForPointer(P, Size);
343 /// containsPointer - Return true if the specified location is represented by
344 /// this alias set, false otherwise. This does not modify the AST object or
346 bool containsPointer(Value *P, unsigned Size) const;
348 /// getAliasAnalysis - Return the underlying alias analysis object used by
350 AliasAnalysis &getAliasAnalysis() const { return AA; }
352 /// deleteValue method - This method is used to remove a pointer value from
353 /// the AliasSetTracker entirely. It should be used when an instruction is
354 /// deleted from the program to update the AST. If you don't use this, you
355 /// would have dangling pointers to deleted instructions.
357 void deleteValue(Value *PtrVal);
359 /// copyValue - This method should be used whenever a preexisting value in the
360 /// program is copied or cloned, introducing a new value. Note that it is ok
361 /// for clients that use this method to introduce the same value multiple
362 /// times: if the tracker already knows about a value, it will ignore the
365 void copyValue(Value *From, Value *To);
368 typedef ilist<AliasSet>::iterator iterator;
369 typedef ilist<AliasSet>::const_iterator const_iterator;
371 const_iterator begin() const { return AliasSets.begin(); }
372 const_iterator end() const { return AliasSets.end(); }
374 iterator begin() { return AliasSets.begin(); }
375 iterator end() { return AliasSets.end(); }
377 void print(raw_ostream &OS) const;
381 friend class AliasSet;
382 void removeAliasSet(AliasSet *AS);
384 // getEntryFor - Just like operator[] on the map, except that it creates an
385 // entry for the pointer if it doesn't already exist.
386 AliasSet::PointerRec &getEntryFor(Value *V) {
387 AliasSet::PointerRec *&Entry = PointerMap[ASTCallbackVH(V, this)];
389 Entry = new AliasSet::PointerRec(V);
393 AliasSet &addPointer(Value *P, unsigned Size, AliasSet::AccessType E,
396 AliasSet &AS = getAliasSetForPointer(P, Size, &NewSet);
400 AliasSet *findAliasSetForPointer(const Value *Ptr, unsigned Size);
402 AliasSet *findAliasSetForCallSite(CallSite CS);
405 inline raw_ostream& operator<<(raw_ostream &OS, const AliasSetTracker &AST) {
410 } // End llvm namespace