LazyValueInfo.h revision cc4d3b25f336eef135cb7125716ecb2c1979e92e 
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 yes/no/dunno results.
35  enum Tristate {
36    Unknown = -1, No = 0, Yes = 1
37  };
38
39
40  // Public query interface.
41
42
43  /// isEqual - Determine whether the specified value is known to be equal or
44  /// not-equal to the specified constant at the end of the specified block.
45  Tristate isEqual(Value *V, Constant *C, BasicBlock *BB);
46
47  /// getConstant - Determine whether the specified value is known to be a
48  /// constant at the end of the specified block.  Return null if not.
49  Constant *getConstant(Value *V, BasicBlock *BB);
50
51
52  // Implementation boilerplate.
53
54  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
55    AU.setPreservesAll();
56  }
57  virtual void releaseMemory();
58  virtual bool runOnFunction(Function &F);
59};
60
61}  // end namespace llvm
62
63#endif
64
65