xref: /freebsd/contrib/llvm-project/llvm/include/llvm/CodeGen/GlobalISel/GISelWorkList.h (revision 81ad626541db97eb356e2c1d4a20eb2a26a766ab)
1  //===- GISelWorkList.h - Worklist for GISel passes ----*- C++ -*-===//
2  //
3  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4  // See https://llvm.org/LICENSE.txt for license information.
5  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6  //
7  //===----------------------------------------------------------------------===//
8  
9  #ifndef LLVM_CODEGEN_GLOBALISEL_GISELWORKLIST_H
10  #define LLVM_CODEGEN_GLOBALISEL_GISELWORKLIST_H
11  
12  #include "llvm/ADT/DenseMap.h"
13  #include "llvm/ADT/SmallVector.h"
14  
15  namespace llvm {
16  
17  class MachineInstr;
18  
19  // Worklist which mostly works similar to InstCombineWorkList, but on
20  // MachineInstrs. The main difference with something like a SetVector is that
21  // erasing an element doesn't move all elements over one place - instead just
22  // nulls out the element of the vector.
23  //
24  // FIXME: Does it make sense to factor out common code with the
25  // instcombinerWorkList?
26  template<unsigned N>
27  class GISelWorkList {
28    SmallVector<MachineInstr *, N> Worklist;
29    DenseMap<MachineInstr *, unsigned> WorklistMap;
30  
31  #if LLVM_ENABLE_ABI_BREAKING_CHECKS
32    bool Finalized = true;
33  #endif
34  
35  public:
GISelWorkList()36    GISelWorkList() : WorklistMap(N) {}
37  
empty()38    bool empty() const { return WorklistMap.empty(); }
39  
size()40    unsigned size() const { return WorklistMap.size(); }
41  
42    // Since we don't know ahead of time how many instructions we're going to add
43    // to the worklist, and migrating densemap's elements is quite expensive
44    // everytime we resize, only insert to the smallvector (typically during the
45    // initial phase of populating lists). Before the worklist can be used,
46    // finalize should be called. Also assert with NDEBUG if list is ever used
47    // without finalizing. Note that unlike insert, we won't check for duplicates
48    // - so the ideal place to use this is during the initial prepopulating phase
49    // of most passes.
deferred_insert(MachineInstr * I)50    void deferred_insert(MachineInstr *I) {
51      Worklist.push_back(I);
52  #if LLVM_ENABLE_ABI_BREAKING_CHECKS
53      Finalized = false;
54  #endif
55    }
56  
57    // This should only be called when using deferred_insert.
58    // This asserts that the WorklistMap is empty, and then
59    // inserts all the elements in the Worklist into the map.
60    // It also asserts if there are any duplicate elements found.
finalize()61    void finalize() {
62      assert(WorklistMap.empty() && "Expecting empty worklistmap");
63      if (Worklist.size() > N)
64        WorklistMap.reserve(Worklist.size());
65      for (unsigned i = 0; i < Worklist.size(); ++i)
66        if (!WorklistMap.try_emplace(Worklist[i], i).second)
67          llvm_unreachable("Duplicate elements in the list");
68  #if LLVM_ENABLE_ABI_BREAKING_CHECKS
69      Finalized = true;
70  #endif
71    }
72  
73    /// Add the specified instruction to the worklist if it isn't already in it.
insert(MachineInstr * I)74    void insert(MachineInstr *I) {
75  #if LLVM_ENABLE_ABI_BREAKING_CHECKS
76      assert(Finalized && "GISelWorkList used without finalizing");
77  #endif
78      if (WorklistMap.try_emplace(I, Worklist.size()).second)
79        Worklist.push_back(I);
80    }
81  
82    /// Remove I from the worklist if it exists.
remove(const MachineInstr * I)83    void remove(const MachineInstr *I) {
84  #if LLVM_ENABLE_ABI_BREAKING_CHECKS
85      assert((Finalized || WorklistMap.empty()) && "Neither finalized nor empty");
86  #endif
87      auto It = WorklistMap.find(I);
88      if (It == WorklistMap.end())
89        return; // Not in worklist.
90  
91      // Don't bother moving everything down, just null out the slot.
92      Worklist[It->second] = nullptr;
93  
94      WorklistMap.erase(It);
95    }
96  
clear()97    void clear() {
98      Worklist.clear();
99      WorklistMap.clear();
100    }
101  
pop_back_val()102    MachineInstr *pop_back_val() {
103  #if LLVM_ENABLE_ABI_BREAKING_CHECKS
104      assert(Finalized && "GISelWorkList used without finalizing");
105  #endif
106      MachineInstr *I;
107      do {
108        I = Worklist.pop_back_val();
109      } while(!I);
110      assert(I && "Pop back on empty worklist");
111      WorklistMap.erase(I);
112      return I;
113    }
114  };
115  
116  } // end namespace llvm.
117  
118  #endif
119