InstCombineWorklist.h revision 263508 
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#define DEBUG_TYPE "instcombine"
14#include "llvm/ADT/DenseMap.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
21namespace llvm {
22
23/// InstCombineWorklist - This is the worklist management logic for
24/// InstCombine.
25class LLVM_LIBRARY_VISIBILITY InstCombineWorklist {
26  SmallVector<Instruction*, 256> Worklist;
27  DenseMap<Instruction*, unsigned> WorklistMap;
28
29  void operator=(const InstCombineWorklist&RHS) LLVM_DELETED_FUNCTION;
30  InstCombineWorklist(const InstCombineWorklist&) LLVM_DELETED_FUNCTION;
31public:
32  InstCombineWorklist() {}
33
34  bool isEmpty() const { return Worklist.empty(); }
35
36  /// Add - Add the specified instruction to the worklist if it isn't already
37  /// in it.
38  void Add(Instruction *I) {
39    if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
40      DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
41      Worklist.push_back(I);
42    }
43  }
44
45  void AddValue(Value *V) {
46    if (Instruction *I = dyn_cast<Instruction>(V))
47      Add(I);
48  }
49
50  /// AddInitialGroup - Add the specified batch of stuff in reverse order.
51  /// which should only be done when the worklist is empty and when the group
52  /// has no duplicates.
53  void AddInitialGroup(Instruction *const *List, unsigned NumEntries) {
54    assert(Worklist.empty() && "Worklist must be empty to add initial group");
55    Worklist.reserve(NumEntries+16);
56    WorklistMap.resize(NumEntries);
57    DEBUG(dbgs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
58    for (unsigned Idx = 0; NumEntries; --NumEntries) {
59      Instruction *I = List[NumEntries-1];
60      WorklistMap.insert(std::make_pair(I, Idx++));
61      Worklist.push_back(I);
62    }
63  }
64
65  // Remove - remove I from the worklist if it exists.
66  void Remove(Instruction *I) {
67    DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
68    if (It == WorklistMap.end()) return; // Not in worklist.
69
70    // Don't bother moving everything down, just null out the slot.
71    Worklist[It->second] = 0;
72
73    WorklistMap.erase(It);
74  }
75
76  Instruction *RemoveOne() {
77    Instruction *I = Worklist.pop_back_val();
78    WorklistMap.erase(I);
79    return I;
80  }
81
82  /// AddUsersToWorkList - When an instruction is simplified, add all users of
83  /// the instruction to the work lists because they might get more simplified
84  /// now.
85  ///
86  void AddUsersToWorkList(Instruction &I) {
87    for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
88         UI != UE; ++UI)
89      Add(cast<Instruction>(*UI));
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#endif
106