InstCombineWorklist.h revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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 INSTCOMBINE_WORKLIST_H
11#define INSTCOMBINE_WORKLIST_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 LLVM_LIBRARY_VISIBILITY InstCombineWorklist {
27  SmallVector<Instruction*, 256> Worklist;
28  DenseMap<Instruction*, unsigned> WorklistMap;
29
30  void operator=(const InstCombineWorklist&RHS) LLVM_DELETED_FUNCTION;
31  InstCombineWorklist(const InstCombineWorklist&) LLVM_DELETED_FUNCTION;
32public:
33  InstCombineWorklist() {}
34
35  bool isEmpty() const { return Worklist.empty(); }
36
37  /// Add - Add the specified instruction to the worklist if it isn't already
38  /// in it.
39  void Add(Instruction *I) {
40    if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
41      DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
42      Worklist.push_back(I);
43    }
44  }
45
46  void AddValue(Value *V) {
47    if (Instruction *I = dyn_cast<Instruction>(V))
48      Add(I);
49  }
50
51  /// AddInitialGroup - Add the specified batch of stuff in reverse order.
52  /// which should only be done when the worklist is empty and when the group
53  /// has no duplicates.
54  void AddInitialGroup(Instruction *const *List, unsigned NumEntries) {
55    assert(Worklist.empty() && "Worklist must be empty to add initial group");
56    Worklist.reserve(NumEntries+16);
57    WorklistMap.resize(NumEntries);
58    DEBUG(dbgs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
59    for (unsigned Idx = 0; NumEntries; --NumEntries) {
60      Instruction *I = List[NumEntries-1];
61      WorklistMap.insert(std::make_pair(I, Idx++));
62      Worklist.push_back(I);
63    }
64  }
65
66  // Remove - remove I from the worklist if it exists.
67  void Remove(Instruction *I) {
68    DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
69    if (It == WorklistMap.end()) return; // Not in worklist.
70
71    // Don't bother moving everything down, just null out the slot.
72    Worklist[It->second] = nullptr;
73
74    WorklistMap.erase(It);
75  }
76
77  Instruction *RemoveOne() {
78    Instruction *I = Worklist.pop_back_val();
79    WorklistMap.erase(I);
80    return I;
81  }
82
83  /// AddUsersToWorkList - When an instruction is simplified, add all users of
84  /// the instruction to the work lists because they might get more simplified
85  /// now.
86  ///
87  void AddUsersToWorkList(Instruction &I) {
88    for (User *U : I.users())
89      Add(cast<Instruction>(U));
90  }
91
92
93  /// Zap - check that the worklist is empty and nuke the backing store for
94  /// the map if it is large.
95  void Zap() {
96    assert(WorklistMap.empty() && "Worklist empty, but map not?");
97
98    // Do an explicit clear, this shrinks the map if needed.
99    WorklistMap.clear();
100  }
101};
102
103} // end namespace llvm.
104
105#undef DEBUG_TYPE
106
107#endif
108