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_LAZYVALUEINFO_H
16#define LLVM_ANALYSIS_LAZYVALUEINFO_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;
30  LazyValueInfo(const LazyValueInfo&); // DO NOT IMPLEMENT.
31  void operator=(const LazyValueInfo&); // DO NOT IMPLEMENT.
32public:
33  static char ID;
34  LazyValueInfo() : FunctionPass(ID), PImpl(0) {
35    initializeLazyValueInfoPass(*PassRegistry::getPassRegistry());
36  }
37  ~LazyValueInfo() { assert(PImpl == 0 && "releaseMemory not called"); }
38
39  /// Tristate - This is used to return true/false/dunno results.
40  enum Tristate {
41    Unknown = -1, False = 0, True = 1
42  };
43
44
45  // Public query interface.
46
47  /// getPredicateOnEdge - Determine whether the specified value comparison
48  /// with a constant is known to be true or false on the specified CFG edge.
49  /// Pred is a CmpInst predicate.
50  Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
51                              BasicBlock *FromBB, BasicBlock *ToBB);
52
53
54  /// getConstant - Determine whether the specified value is known to be a
55  /// constant at the end of the specified block.  Return null if not.
56  Constant *getConstant(Value *V, BasicBlock *BB);
57
58  /// getConstantOnEdge - Determine whether the specified value is known to be a
59  /// constant on the specified edge.  Return null if not.
60  Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB);
61
62  /// threadEdge - Inform the analysis cache that we have threaded an edge from
63  /// PredBB to OldSucc to be from PredBB to NewSucc instead.
64  void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc);
65
66  /// eraseBlock - Inform the analysis cache that we have erased a block.
67  void eraseBlock(BasicBlock *BB);
68
69  // Implementation boilerplate.
70
71  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
72    AU.setPreservesAll();
73  }
74  virtual void releaseMemory();
75  virtual bool runOnFunction(Function &F);
76};
77
78}  // end namespace llvm
79
80#endif
81
82