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/iterator.h"
24 #include "llvm/ADT/ilist.h"
25 #include "llvm/ADT/ilist_node.h"
35 class AliasSetTracker;
38 class AliasSet : public ilist_node<AliasSet> {
39 friend class AliasSetTracker;
42 Value *Val; // The pointer this record corresponds to.
43 PointerRec **PrevInList, *NextInList;
48 : Val(V), PrevInList(0), NextInList(0), AS(0), Size(0) {}
50 Value *getValue() const { return Val; }
52 PointerRec *getNext() const { return NextInList; }
53 bool hasAliasSet() const { return AS != 0; }
55 PointerRec** setPrevInList(PointerRec **PIL) {
60 void updateSize(unsigned NewSize) {
61 if (NewSize > Size) Size = NewSize;
64 unsigned getSize() const { return Size; }
66 AliasSet *getAliasSet(AliasSetTracker &AST) {
67 assert(AS && "No AliasSet yet!");
70 AS = OldAS->getForwardedTarget(AST);
77 void setAliasSet(AliasSet *as) {
78 assert(AS == 0 && "Already have an alias set!");
82 void eraseFromList() {
83 if (NextInList) NextInList->PrevInList = PrevInList;
84 *PrevInList = NextInList;
85 if (AS->PtrListEnd == &NextInList) {
86 AS->PtrListEnd = PrevInList;
87 assert(*AS->PtrListEnd == 0 && "List not terminated right!");
93 PointerRec *PtrList, **PtrListEnd; // Doubly linked list of nodes.
94 AliasSet *Forward; // Forwarding pointer.
95 AliasSet *Next, *Prev; // Doubly linked list of AliasSets.
97 std::vector<CallSite> CallSites; // All calls & invokes in this alias set.
99 // RefCount - Number of nodes pointing to this AliasSet plus the number of
100 // AliasSets forwarding to it.
101 unsigned RefCount : 28;
103 /// AccessType - Keep track of whether this alias set merely refers to the
104 /// locations of memory, whether it modifies the memory, or whether it does
105 /// both. The lattice goes from "NoModRef" to either Refs or Mods, then to
106 /// ModRef as necessary.
109 NoModRef = 0, Refs = 1, // Ref = bit 1
110 Mods = 2, ModRef = 3 // Mod = bit 2
112 unsigned AccessTy : 2;
114 /// AliasType - Keep track the relationships between the pointers in the set.
115 /// Lattice goes from MustAlias to MayAlias.
118 MustAlias = 0, MayAlias = 1
120 unsigned AliasTy : 1;
122 // Volatile - True if this alias set contains volatile loads or stores.
125 void addRef() { ++RefCount; }
126 void dropRef(AliasSetTracker &AST) {
127 assert(RefCount >= 1 && "Invalid reference count detected!");
129 removeFromTracker(AST);
134 bool isRef() const { return AccessTy & Refs; }
135 bool isMod() const { return AccessTy & Mods; }
136 bool isMustAlias() const { return AliasTy == MustAlias; }
137 bool isMayAlias() const { return AliasTy == MayAlias; }
139 // isVolatile - Return true if this alias set contains volatile loads or
141 bool isVolatile() const { return Volatile; }
143 /// isForwardingAliasSet - Return true if this alias set should be ignored as
144 /// part of the AliasSetTracker object.
145 bool isForwardingAliasSet() const { return Forward; }
147 /// mergeSetIn - Merge the specified alias set into this alias set...
149 void mergeSetIn(AliasSet &AS, AliasSetTracker &AST);
151 // Alias Set iteration - Allow access to all of the pointer which are part of
154 iterator begin() const { return iterator(PtrList); }
155 iterator end() const { return iterator(); }
156 bool empty() const { return PtrList == 0; }
158 void print(std::ostream &OS) const;
159 void print(std::ostream *OS) const { if (OS) print(*OS); }
162 /// Define an iterator for alias sets... this is just a forward iterator.
163 class iterator : public forward_iterator<PointerRec, ptrdiff_t> {
166 explicit iterator(PointerRec *CN = 0) : CurNode(CN) {}
168 bool operator==(const iterator& x) const {
169 return CurNode == x.CurNode;
171 bool operator!=(const iterator& x) const { return !operator==(x); }
173 const iterator &operator=(const iterator &I) {
178 value_type &operator*() const {
179 assert(CurNode && "Dereferencing AliasSet.end()!");
182 value_type *operator->() const { return &operator*(); }
184 Value *getPointer() const { return CurNode->getValue(); }
185 unsigned getSize() const { return CurNode->getSize(); }
187 iterator& operator++() { // Preincrement
188 assert(CurNode && "Advancing past AliasSet.end()!");
189 CurNode = CurNode->getNext();
192 iterator operator++(int) { // Postincrement
193 iterator tmp = *this; ++*this; return tmp;
198 // Can only be created by AliasSetTracker. Also, ilist creates one
199 // to serve as a sentinel.
200 friend struct ilist_sentinel_traits<AliasSet>;
201 AliasSet() : PtrList(0), PtrListEnd(&PtrList), Forward(0), RefCount(0),
202 AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) {
205 AliasSet(const AliasSet &AS); // do not implement
206 void operator=(const AliasSet &AS); // do not implement
208 PointerRec *getSomePointer() const {
212 /// getForwardedTarget - Return the real alias set this represents. If this
213 /// has been merged with another set and is forwarding, return the ultimate
214 /// destination set. This also implements the union-find collapsing as well.
215 AliasSet *getForwardedTarget(AliasSetTracker &AST) {
216 if (!Forward) return this;
218 AliasSet *Dest = Forward->getForwardedTarget(AST);
219 if (Dest != Forward) {
221 Forward->dropRef(AST);
227 void removeFromTracker(AliasSetTracker &AST);
229 void addPointer(AliasSetTracker &AST, PointerRec &Entry, unsigned Size,
230 bool KnownMustAlias = false);
231 void addCallSite(CallSite CS, AliasAnalysis &AA);
232 void removeCallSite(CallSite CS) {
233 for (size_t i = 0, e = CallSites.size(); i != e; ++i)
234 if (CallSites[i].getInstruction() == CS.getInstruction()) {
235 CallSites[i] = CallSites.back();
236 CallSites.pop_back();
239 void setVolatile() { Volatile = true; }
241 /// aliasesPointer - Return true if the specified pointer "may" (or must)
242 /// alias one of the members in the set.
244 bool aliasesPointer(const Value *Ptr, unsigned Size, AliasAnalysis &AA) const;
245 bool aliasesCallSite(CallSite CS, AliasAnalysis &AA) const;
248 inline std::ostream& operator<<(std::ostream &OS, const AliasSet &AS) {
254 class AliasSetTracker {
255 /// CallbackVH - A CallbackVH to arrange for AliasSetTracker to be
256 /// notified whenever a Value is deleted.
257 class ASTCallbackVH : public CallbackVH {
258 AliasSetTracker *AST;
259 virtual void deleted();
261 ASTCallbackVH(Value *V, AliasSetTracker *AST = 0);
262 ASTCallbackVH &operator=(Value *V);
264 /// ASTCallbackVHDenseMapInfo - Traits to tell DenseMap that ASTCallbackVH
265 /// is not a POD (it needs its destructor called).
266 struct ASTCallbackVHDenseMapInfo : public DenseMapInfo<Value *> {
267 static bool isPod() { return false; }
271 ilist<AliasSet> AliasSets;
273 typedef DenseMap<ASTCallbackVH, AliasSet::PointerRec*,
274 ASTCallbackVHDenseMapInfo>
277 // Map from pointers to their node
278 PointerMapType PointerMap;
281 /// AliasSetTracker ctor - Create an empty collection of AliasSets, and use
282 /// the specified alias analysis object to disambiguate load and store
284 explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {}
285 ~AliasSetTracker() { clear(); }
287 /// add methods - These methods are used to add different types of
288 /// instructions to the alias sets. Adding a new instruction can result in
289 /// one of three actions happening:
291 /// 1. If the instruction doesn't alias any other sets, create a new set.
292 /// 2. If the instruction aliases exactly one set, add it to the set
293 /// 3. If the instruction aliases multiple sets, merge the sets, and add
294 /// the instruction to the result.
296 /// These methods return true if inserting the instruction resulted in the
297 /// addition of a new alias set (i.e., the pointer did not alias anything).
299 bool add(Value *Ptr, unsigned Size); // Add a location
300 bool add(LoadInst *LI);
301 bool add(StoreInst *SI);
302 bool add(FreeInst *FI);
303 bool add(VAArgInst *VAAI);
304 bool add(CallSite CS); // Call/Invoke instructions
305 bool add(CallInst *CI) { return add(CallSite(CI)); }
306 bool add(InvokeInst *II) { return add(CallSite(II)); }
307 bool add(Instruction *I); // Dispatch to one of the other add methods...
308 void add(BasicBlock &BB); // Add all instructions in basic block
309 void add(const AliasSetTracker &AST); // Add alias relations from another AST
311 /// remove methods - These methods are used to remove all entries that might
312 /// be aliased by the specified instruction. These methods return true if any
313 /// alias sets were eliminated.
314 bool remove(Value *Ptr, unsigned Size); // Remove a location
315 bool remove(LoadInst *LI);
316 bool remove(StoreInst *SI);
317 bool remove(FreeInst *FI);
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(std::ostream &OS) const;
378 void print(std::ostream *OS) const { if (OS) print(*OS); }
382 friend class AliasSet;
383 void removeAliasSet(AliasSet *AS);
385 // getEntryFor - Just like operator[] on the map, except that it creates an
386 // entry for the pointer if it doesn't already exist.
387 AliasSet::PointerRec &getEntryFor(Value *V) {
388 AliasSet::PointerRec *&Entry = PointerMap[ASTCallbackVH(V, this)];
390 Entry = new AliasSet::PointerRec(V);
394 AliasSet &addPointer(Value *P, unsigned Size, AliasSet::AccessType E,
397 AliasSet &AS = getAliasSetForPointer(P, Size, &NewSet);
401 AliasSet *findAliasSetForPointer(const Value *Ptr, unsigned Size);
403 AliasSet *findAliasSetForCallSite(CallSite CS);
406 inline std::ostream& operator<<(std::ostream &OS, const AliasSetTracker &AST) {
411 } // End llvm namespace