InstCombineWorklist.h revision 296417 
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/SmallVector.h"
15#include "llvm/IR/Instruction.h"
16#include "llvm/Support/Compiler.h"
17#include "llvm/Support/Debug.h"
18#include "llvm/Support/raw_ostream.h"
19
20#define DEBUG_TYPE "instcombine"
21
22namespace llvm {
23
24/// InstCombineWorklist - This is the worklist management logic for
25/// InstCombine.
26class InstCombineWorklist {
27  SmallVector<Instruction*, 256> Worklist;
28  DenseMap<Instruction*, unsigned> WorklistMap;
29
30  void operator=(const InstCombineWorklist&RHS) = delete;
31  InstCombineWorklist(const InstCombineWorklist&) = delete;
32public:
33  InstCombineWorklist() {}
34
35  InstCombineWorklist(InstCombineWorklist &&Arg)
36      : Worklist(std::move(Arg.Worklist)),
37        WorklistMap(std::move(Arg.WorklistMap)) {}
38  InstCombineWorklist &operator=(InstCombineWorklist &&RHS) {
39    Worklist = std::move(RHS.Worklist);
40    WorklistMap = std::move(RHS.WorklistMap);
41    return *this;
42  }
43
44  bool isEmpty() const { return Worklist.empty(); }
45
46  /// Add - Add the specified instruction to the worklist if it isn't already
47  /// in it.
48  void Add(Instruction *I) {
49    if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
50      DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
51      Worklist.push_back(I);
52    }
53  }
54
55  void AddValue(Value *V) {
56    if (Instruction *I = dyn_cast<Instruction>(V))
57      Add(I);
58  }
59
60  /// AddInitialGroup - Add the specified batch of stuff in reverse order.
61  /// which should only be done when the worklist is empty and when the group
62  /// has no duplicates.
63  void AddInitialGroup(ArrayRef<Instruction *> List) {
64    assert(Worklist.empty() && "Worklist must be empty to add initial group");
65    Worklist.reserve(List.size()+16);
66    WorklistMap.resize(List.size());
67    DEBUG(dbgs() << "IC: ADDING: " << List.size() << " instrs to worklist\n");
68    unsigned Idx = 0;
69    for (Instruction *I : reverse(List)) {
70      WorklistMap.insert(std::make_pair(I, Idx++));
71      Worklist.push_back(I);
72    }
73  }
74
75  // Remove - remove I from the worklist if it exists.
76  void Remove(Instruction *I) {
77    DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
78    if (It == WorklistMap.end()) return; // Not in worklist.
79
80    // Don't bother moving everything down, just null out the slot.
81    Worklist[It->second] = nullptr;
82
83    WorklistMap.erase(It);
84  }
85
86  Instruction *RemoveOne() {
87    Instruction *I = Worklist.pop_back_val();
88    WorklistMap.erase(I);
89    return I;
90  }
91
92  /// AddUsersToWorkList - When an instruction is simplified, add all users of
93  /// the instruction to the work lists because they might get more simplified
94  /// now.
95  ///
96  void AddUsersToWorkList(Instruction &I) {
97    for (User *U : I.users())
98      Add(cast<Instruction>(U));
99  }
100
101
102  /// Zap - check that the worklist is empty and nuke the backing store for
103  /// the map if it is large.
104  void Zap() {
105    assert(WorklistMap.empty() && "Worklist empty, but map not?");
106
107    // Do an explicit clear, this shrinks the map if needed.
108    WorklistMap.clear();
109  }
110};
111
112} // end namespace llvm.
113
114#undef DEBUG_TYPE
115
116#endif
117