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 
23 namespace llvm {
24 
25 /// InstCombineWorklist - This is the worklist management logic for
26 /// InstCombine.
27 class InstCombineWorklist {
28   SmallVector<Instruction*, 256> Worklist;
29   DenseMap<Instruction*, unsigned> WorklistMap;
30 
31 public:
32   InstCombineWorklist() = default;
33 
34   InstCombineWorklist(InstCombineWorklist &&) = default;
35   InstCombineWorklist &operator=(InstCombineWorklist &&) = default;
36 
isEmpty()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.
Add(Instruction * I)41   void Add(Instruction *I) {
42     if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
43       LLVM_DEBUG(dbgs() << "IC: ADD: " << *I << '\n');
44       Worklist.push_back(I);
45     }
46   }
47 
AddValue(Value * V)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.
AddInitialGroup(ArrayRef<Instruction * > List)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     LLVM_DEBUG(dbgs() << "IC: ADDING: " << List.size()
61                       << " instrs to worklist\n");
62     unsigned Idx = 0;
63     for (Instruction *I : reverse(List)) {
64       WorklistMap.insert(std::make_pair(I, Idx++));
65       Worklist.push_back(I);
66     }
67   }
68 
69   // Remove - remove I from the worklist if it exists.
Remove(Instruction * I)70   void Remove(Instruction *I) {
71     DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
72     if (It == WorklistMap.end()) return; // Not in worklist.
73 
74     // Don't bother moving everything down, just null out the slot.
75     Worklist[It->second] = nullptr;
76 
77     WorklistMap.erase(It);
78   }
79 
RemoveOne()80   Instruction *RemoveOne() {
81     Instruction *I = Worklist.pop_back_val();
82     WorklistMap.erase(I);
83     return I;
84   }
85 
86   /// AddUsersToWorkList - When an instruction is simplified, add all users of
87   /// the instruction to the work lists because they might get more simplified
88   /// now.
89   ///
AddUsersToWorkList(Instruction & I)90   void AddUsersToWorkList(Instruction &I) {
91     for (User *U : I.users())
92       Add(cast<Instruction>(U));
93   }
94 
95 
96   /// Zap - check that the worklist is empty and nuke the backing store for
97   /// the map if it is large.
Zap()98   void Zap() {
99     assert(WorklistMap.empty() && "Worklist empty, but map not?");
100 
101     // Do an explicit clear, this shrinks the map if needed.
102     WorklistMap.clear();
103   }
104 };
105 
106 } // end namespace llvm.
107 
108 #undef DEBUG_TYPE
109 
110 #endif
111