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 DataLayout;
23  class TargetLibraryInfo;
24  class Value;
25
26/// LazyValueInfo - This pass computes, caches, and vends lazy value constraint
27/// information.
28class LazyValueInfo : public FunctionPass {
29  const DataLayout *DL;
30  class TargetLibraryInfo *TLI;
31  void *PImpl;
32  LazyValueInfo(const LazyValueInfo&) LLVM_DELETED_FUNCTION;
33  void operator=(const LazyValueInfo&) LLVM_DELETED_FUNCTION;
34public:
35  static char ID;
36  LazyValueInfo() : FunctionPass(ID), PImpl(nullptr) {
37    initializeLazyValueInfoPass(*PassRegistry::getPassRegistry());
38  }
39  ~LazyValueInfo() { assert(!PImpl && "releaseMemory not called"); }
40
41  /// Tristate - This is used to return true/false/dunno results.
42  enum Tristate {
43    Unknown = -1, False = 0, True = 1
44  };
45
46
47  // Public query interface.
48
49  /// getPredicateOnEdge - Determine whether the specified value comparison
50  /// with a constant is known to be true or false on the specified CFG edge.
51  /// Pred is a CmpInst predicate.
52  Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
53                              BasicBlock *FromBB, BasicBlock *ToBB);
54
55
56  /// getConstant - Determine whether the specified value is known to be a
57  /// constant at the end of the specified block.  Return null if not.
58  Constant *getConstant(Value *V, BasicBlock *BB);
59
60  /// getConstantOnEdge - Determine whether the specified value is known to be a
61  /// constant on the specified edge.  Return null if not.
62  Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB);
63
64  /// threadEdge - Inform the analysis cache that we have threaded an edge from
65  /// PredBB to OldSucc to be from PredBB to NewSucc instead.
66  void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc);
67
68  /// eraseBlock - Inform the analysis cache that we have erased a block.
69  void eraseBlock(BasicBlock *BB);
70
71  // Implementation boilerplate.
72
73  void getAnalysisUsage(AnalysisUsage &AU) const override;
74  void releaseMemory() override;
75  bool runOnFunction(Function &F) override;
76};
77
78}  // end namespace llvm
79
80#endif
81
82