InstCombineWorklist.h revision 314564 
1//===- InstCombineWorklist.h - Worklist for InstCombine pass ----*- 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#ifndef LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINEWORKLIST_H
11#define LLVM_TRANSFORMS_INSTCOMBINE_INSTCOMBINEWORKLIST_H
12
13#include "llvm/ADT/DenseMap.h"
14#include "llvm/ADT/STLExtras.h"
15#include "llvm/ADT/SmallVector.h"
16#include "llvm/IR/Instruction.h"
17#include "llvm/Support/Compiler.h"
18#include "llvm/Support/Debug.h"
19#include "llvm/Support/raw_ostream.h"
20
21#define DEBUG_TYPE "instcombine"
22
23namespace llvm {
24
25/// InstCombineWorklist - This is the worklist management logic for
26/// InstCombine.
27class InstCombineWorklist {
28  SmallVector<Instruction*, 256> Worklist;
29  DenseMap<Instruction*, unsigned> WorklistMap;
30
31public:
32  InstCombineWorklist() = default;
33
34  InstCombineWorklist(InstCombineWorklist &&) = default;
35  InstCombineWorklist &operator=(InstCombineWorklist &&) = default;
36
37  bool isEmpty() const { return Worklist.empty(); }
38
39  /// Add - Add the specified instruction to the worklist if it isn't already
40  /// in it.
41  void Add(Instruction *I) {
42    if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
43      DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
44      Worklist.push_back(I);
45    }
46  }
47
48  void AddValue(Value *V) {
49    if (Instruction *I = dyn_cast<Instruction>(V))
50      Add(I);
51  }
52
53  /// AddInitialGroup - Add the specified batch of stuff in reverse order.
54  /// which should only be done when the worklist is empty and when the group
55  /// has no duplicates.
56  void AddInitialGroup(ArrayRef<Instruction *> List) {
57    assert(Worklist.empty() && "Worklist must be empty to add initial group");
58    Worklist.reserve(List.size()+16);
59    WorklistMap.reserve(List.size());
60    DEBUG(dbgs() << "IC: ADDING: " << List.size() << " instrs to worklist\n");
61    unsigned Idx = 0;
62    for (Instruction *I : reverse(List)) {
63      WorklistMap.insert(std::make_pair(I, Idx++));
64      Worklist.push_back(I);
65    }
66  }
67
68  // Remove - remove I from the worklist if it exists.
69  void Remove(Instruction *I) {
70    DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
71    if (It == WorklistMap.end()) return; // Not in worklist.
72
73    // Don't bother moving everything down, just null out the slot.
74    Worklist[It->second] = nullptr;
75
76    WorklistMap.erase(It);
77  }
78
79  Instruction *RemoveOne() {
80    Instruction *I = Worklist.pop_back_val();
81    WorklistMap.erase(I);
82    return I;
83  }
84
85  /// AddUsersToWorkList - When an instruction is simplified, add all users of
86  /// the instruction to the work lists because they might get more simplified
87  /// now.
88  ///
89  void AddUsersToWorkList(Instruction &I) {
90    for (User *U : I.users())
91      Add(cast<Instruction>(U));
92  }
93
94
95  /// Zap - check that the worklist is empty and nuke the backing store for
96  /// the map if it is large.
97  void Zap() {
98    assert(WorklistMap.empty() && "Worklist empty, but map not?");
99
100    // Do an explicit clear, this shrinks the map if needed.
101    WorklistMap.clear();
102  }
103};
104
105} // end namespace llvm.
106
107#undef DEBUG_TYPE
108
109#endif
110