1 //===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- 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 implements bookkeeping for "interesting" users of expressions
11 // computed from induction variables.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ANALYSIS_IVUSERS_H
16 #define LLVM_ANALYSIS_IVUSERS_H
18 #include "llvm/Analysis/LoopPass.h"
19 #include "llvm/Support/ValueHandle.h"
27 class ScalarEvolution;
30 /// IVStrideUse - Keep track of one use of a strided induction variable.
31 /// The Expr member keeps track of the expression, User is the actual user
32 /// instruction of the operand, and 'OperandValToReplace' is the operand of
33 /// the User that is the use.
34 class IVStrideUse : public CallbackVH, public ilist_node<IVStrideUse> {
36 IVStrideUse(IVUsers *P, const SCEV *S, const SCEV *Off,
37 Instruction* U, Value *O)
38 : CallbackVH(U), Parent(P), Stride(S), Offset(Off),
39 OperandValToReplace(O), IsUseOfPostIncrementedValue(false) {
42 /// getUser - Return the user instruction for this use.
43 Instruction *getUser() const {
44 return cast<Instruction>(getValPtr());
47 /// setUser - Assign a new user instruction for this use.
48 void setUser(Instruction *NewUser) {
52 /// getParent - Return a pointer to the IVUsers that owns
54 IVUsers *getParent() const { return Parent; }
56 /// getStride - Return the expression for the stride for the use.
57 const SCEV *getStride() const { return Stride; }
59 /// setStride - Assign a new stride to this use.
60 void setStride(const SCEV *Val) {
64 /// getOffset - Return the offset to add to a theoretical induction
65 /// variable that starts at zero and counts up by the stride to compute
66 /// the value for the use. This always has the same type as the stride.
67 const SCEV *getOffset() const { return Offset; }
69 /// setOffset - Assign a new offset to this use.
70 void setOffset(const SCEV *Val) {
74 /// getOperandValToReplace - Return the Value of the operand in the user
75 /// instruction that this IVStrideUse is representing.
76 Value *getOperandValToReplace() const {
77 return OperandValToReplace;
80 /// setOperandValToReplace - Assign a new Value as the operand value
82 void setOperandValToReplace(Value *Op) {
83 OperandValToReplace = Op;
86 /// isUseOfPostIncrementedValue - True if this should use the
87 /// post-incremented version of this IV, not the preincremented version.
88 /// This can only be set in special cases, such as the terminating setcc
89 /// instruction for a loop or uses dominated by the loop.
90 bool isUseOfPostIncrementedValue() const {
91 return IsUseOfPostIncrementedValue;
94 /// setIsUseOfPostIncrmentedValue - set the flag that indicates whether
95 /// this is a post-increment use.
96 void setIsUseOfPostIncrementedValue(bool Val) {
97 IsUseOfPostIncrementedValue = Val;
101 /// Parent - a pointer to the IVUsers that owns this IVStrideUse.
104 /// Stride - The stride for this use.
107 /// Offset - The offset to add to the base induction expression.
110 /// OperandValToReplace - The Value of the operand in the user instruction
111 /// that this IVStrideUse is representing.
112 WeakVH OperandValToReplace;
114 /// IsUseOfPostIncrementedValue - True if this should use the
115 /// post-incremented version of this IV, not the preincremented version.
116 bool IsUseOfPostIncrementedValue;
118 /// Deleted - Implementation of CallbackVH virtual function to
119 /// receive notification when the User is deleted.
120 virtual void deleted();
123 template<> struct ilist_traits<IVStrideUse>
124 : public ilist_default_traits<IVStrideUse> {
125 // createSentinel is used to get hold of a node that marks the end of
127 // The sentinel is relative to this instance, so we use a non-static
129 IVStrideUse *createSentinel() const {
130 // since i(p)lists always publicly derive from the corresponding
131 // traits, placing a data member in this class will augment i(p)list.
132 // But since the NodeTy is expected to publicly derive from
133 // ilist_node<NodeTy>, there is a legal viable downcast from it
134 // to NodeTy. We use this trick to superpose i(p)list with a "ghostly"
135 // NodeTy, which becomes the sentinel. Dereferencing the sentinel is
136 // forbidden (save the ilist_node<NodeTy>) so no one will ever notice
137 // the superposition.
138 return static_cast<IVStrideUse*>(&Sentinel);
140 static void destroySentinel(IVStrideUse*) {}
142 IVStrideUse *provideInitialHead() const { return createSentinel(); }
143 IVStrideUse *ensureHead(IVStrideUse*) const { return createSentinel(); }
144 static void noteHead(IVStrideUse*, IVStrideUse*) {}
147 mutable ilist_node<IVStrideUse> Sentinel;
150 class IVUsers : public LoopPass {
151 friend class IVStrideUse;
156 SmallPtrSet<Instruction*,16> Processed;
158 /// IVUses - A list of all tracked IV uses of induction variable expressions
159 /// we are interested in.
160 ilist<IVStrideUse> IVUses;
162 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
164 virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
166 virtual void releaseMemory();
169 static char ID; // Pass ID, replacement for typeid
172 /// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
173 /// reducible SCEV, recursively add its users to the IVUsesByStride set and
174 /// return true. Otherwise, return false.
175 bool AddUsersIfInteresting(Instruction *I);
177 IVStrideUse &AddUser(const SCEV *Stride, const SCEV *Offset,
178 Instruction *User, Value *Operand);
180 /// getReplacementExpr - Return a SCEV expression which computes the
181 /// value of the OperandValToReplace of the given IVStrideUse.
182 const SCEV *getReplacementExpr(const IVStrideUse &U) const;
184 /// getCanonicalExpr - Return a SCEV expression which computes the
185 /// value of the SCEV of the given IVStrideUse, ignoring the
186 /// isUseOfPostIncrementedValue flag.
187 const SCEV *getCanonicalExpr(const IVStrideUse &U) const;
189 typedef ilist<IVStrideUse>::iterator iterator;
190 typedef ilist<IVStrideUse>::const_iterator const_iterator;
191 iterator begin() { return IVUses.begin(); }
192 iterator end() { return IVUses.end(); }
193 const_iterator begin() const { return IVUses.begin(); }
194 const_iterator end() const { return IVUses.end(); }
195 bool empty() const { return IVUses.empty(); }
197 void print(raw_ostream &OS, const Module* = 0) const;
199 /// dump - This method is used for debugging.
203 Pass *createIVUsersPass();