LazyValueInfo.h revision b52675b643db496bcea218bd3d5fc5e23f523c22 
1//===- LazyValueInfo.h - Value constraint analysis --------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the interface for lazy computation of value constraint
11// information.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_ANALYSIS_LIVEVALUES_H
16#define LLVM_ANALYSIS_LIVEVALUES_H
17
18#include "llvm/Pass.h"
19
20namespace llvm {
21  class Constant;
22  class TargetData;
23  class Value;
24
25/// LazyValueInfo - This pass computes, caches, and vends lazy value constraint
26/// information.
27class LazyValueInfo : public FunctionPass {
28  class TargetData *TD;
29  void *PImpl;
30public:
31  static char ID;
32  LazyValueInfo() : FunctionPass(&ID), PImpl(0) {}
33
34  /// Tristate - This is used to return true/false/dunno results.
35  enum Tristate {
36    Unknown = -1, False = 0, True = 1
37  };
38
39
40  // Public query interface.
41
42  /// getPredicateOnEdge - Determine whether the specified value comparison
43  /// with a constant is known to be true or false on the specified CFG edge.
44  /// Pred is a CmpInst predicate.
45  Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
46                              BasicBlock *FromBB, BasicBlock *ToBB);
47
48
49  /// getConstant - Determine whether the specified value is known to be a
50  /// constant at the end of the specified block.  Return null if not.
51  Constant *getConstant(Value *V, BasicBlock *BB);
52
53  /// getConstantOnEdge - Determine whether the specified value is known to be a
54  /// constant on the specified edge.  Return null if not.
55  Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB);
56
57
58  // Implementation boilerplate.
59
60  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
61    AU.setPreservesAll();
62  }
63  virtual void releaseMemory();
64  virtual bool runOnFunction(Function &F);
65};
66
67}  // end namespace llvm
68
69#endif
70
71