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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 
22 namespace llvm {
23 
24 /// InstCombineWorklist - This is the worklist management logic for
25 /// InstCombine.
26 class InstCombineWorklist {
27   SmallVector<Instruction*, 256> Worklist;
28   DenseMap<Instruction*, unsigned> WorklistMap;
29 
30   void operator=(const InstCombineWorklist&RHS) = delete;
31   InstCombineWorklist(const InstCombineWorklist&) = delete;
32 public:
InstCombineWorklist()33   InstCombineWorklist() {}
34 
InstCombineWorklist(InstCombineWorklist && Arg)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 
isEmpty()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.
Add(Instruction * I)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 
AddValue(Value * V)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.
AddInitialGroup(ArrayRef<Instruction * > List)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.
Remove(Instruction * I)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 
RemoveOne()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   ///
AddUsersToWorkList(Instruction & I)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.
Zap()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