LLVM  9.0.0svn
GISelWorkList.h
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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_GISEL_WORKLIST_H
10 #define LLVM_GISEL_WORKLIST_H
11 
12 #include "llvm/ADT/DenseMap.h"
13 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/Support/Debug.h"
17 
18 namespace llvm {
19 
20 class MachineInstr;
21 class MachineFunction;
22 
23 // Worklist which mostly works similar to InstCombineWorkList, but on
24 // MachineInstrs. The main difference with something like a SetVector is that
25 // erasing an element doesn't move all elements over one place - instead just
26 // nulls out the element of the vector.
27 //
28 // FIXME: Does it make sense to factor out common code with the
29 // instcombinerWorkList?
30 template<unsigned N>
34 
35 #ifndef NDEBUG
36  bool Finalized = true;
37 #endif
38 
39 public:
40  GISelWorkList() : WorklistMap(N) {}
41 
42  bool empty() const { return WorklistMap.empty(); }
43 
44  unsigned size() const { return WorklistMap.size(); }
45 
46  // Since we don't know ahead of time how many instructions we're going to add
47  // to the worklist, and migrating densemap's elements is quite expensive
48  // everytime we resize, only insert to the smallvector (typically during the
49  // initial phase of populating lists). Before the worklist can be used,
50  // finalize should be called. Also assert with NDEBUG if list is ever used
51  // without finalizing. Note that unlike insert, we won't check for duplicates
52  // - so the ideal place to use this is during the initial prepopulating phase
53  // of most passes.
55  Worklist.push_back(I);
56 #ifndef NDEBUG
57  Finalized = false;
58 #endif
59  }
60 
61  // This should only be called when using deferred_insert.
62  // This asserts that the WorklistMap is empty, and then
63  // inserts all the elements in the Worklist into the map.
64  // It also asserts if there are any duplicate elements found.
65  void finalize() {
66  assert(WorklistMap.empty() && "Expecting empty worklistmap");
67  if (Worklist.size() > N)
68  WorklistMap.reserve(Worklist.size());
69  for (unsigned i = 0; i < Worklist.size(); ++i)
70  if (!WorklistMap.try_emplace(Worklist[i], i).second)
71  llvm_unreachable("Duplicate elements in the list");
72 #ifndef NDEBUG
73  Finalized = true;
74 #endif
75  }
76 
77  /// Add the specified instruction to the worklist if it isn't already in it.
79  assert(Finalized && "GISelWorkList used without finalizing");
80  if (WorklistMap.try_emplace(I, Worklist.size()).second)
81  Worklist.push_back(I);
82  }
83 
84  /// Remove I from the worklist if it exists.
85  void remove(const MachineInstr *I) {
86  assert((Finalized || WorklistMap.empty()) && "Neither finalized nor empty");
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 
97  void clear() {
98  Worklist.clear();
99  WorklistMap.clear();
100  }
101 
103  assert(Finalized && "GISelWorkList used without finalizing");
104  MachineInstr *I;
105  do {
106  I = Worklist.pop_back_val();
107  } while(!I);
108  assert(I && "Pop back on empty worklist");
109  WorklistMap.erase(I);
110  return I;
111  }
112 };
113 
114 } // end namespace llvm.
115 
116 #endif
void deferred_insert(MachineInstr *I)
Definition: GISelWorkList.h:54
This class represents lattice values for constants.
Definition: AllocatorList.h:23
bool empty() const
Definition: GISelWorkList.h:42
unsigned second
void reserve(size_type NumEntries)
Grow the densemap so that it can contain at least NumEntries items before resizing again...
Definition: DenseMap.h:129
size_t size() const
Definition: SmallVector.h:52
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
unsigned size() const
Definition: GISelWorkList.h:44
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:374
MachineInstr * pop_back_val()
void insert(MachineInstr *I)
Add the specified instruction to the worklist if it isn&#39;t already in it.
Definition: GISelWorkList.h:78
Representation of each machine instruction.
Definition: MachineInstr.h:64
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())