lib/Transforms/InstCombine/InstCombineWorklist.h

   1 //===- InstCombineWorklist.h - Worklist for the InstCombine pass ----------===//
   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/Instruction.h"
  15 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/Compiler.h"
  17 #include "llvm/ADT/SmallVector.h"
  18 #include "llvm/ADT/DenseMap.h"
  19 #include "llvm/Support/raw_ostream.h"
  20
  21 namespace llvm {
  22
  23 /// InstCombineWorklist - This is the worklist management logic for
  24 /// InstCombine.
  25 class LLVM_LIBRARY_VISIBILITY InstCombineWorklist {
  26   SmallVector<Instruction*, 256> Worklist;
  27   DenseMap<Instruction*, unsigned> WorklistMap;
  28
  29   void operator=(const InstCombineWorklist&RHS);   // DO NOT IMPLEMENT
  30   InstCombineWorklist(const InstCombineWorklist&); // DO NOT IMPLEMENT
  31 public:
  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(errs() << "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(errs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
  58     for (; NumEntries; --NumEntries) {
  59       Instruction *I = List[NumEntries-1];
  60       WorklistMap.insert(std::make_pair(I, Worklist.size()));
  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.back();
  78     Worklist.pop_back();
  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 (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
  89          UI != UE; ++UI)
  90       Add(cast<Instruction>(*UI));
  91   }
  92
  93
  94   /// Zap - check that the worklist is empty and nuke the backing store for
  95   /// the map if it is large.
  96   void Zap() {
  97     assert(WorklistMap.empty() && "Worklist empty, but map not?");
  98
  99     // Do an explicit clear, this shrinks the map if needed.
 100     WorklistMap.clear();
 101   }
 102 };
 103
 104 } // end namespace llvm.
 105
 106 #endif