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: |
36 | GISelWorkList() : WorklistMap(N) {} |
37 | |
38 | bool empty() const { return WorklistMap.empty(); } |
39 | |
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. |
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. |
61 | void finalize() { |
62 | assert(WorklistMap.empty() && "Expecting empty worklistmap" ); |
63 | if (Worklist.size() > N) |
64 | WorklistMap.reserve(NumEntries: 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. |
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. |
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(Val: 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(I: It); |
95 | } |
96 | |
97 | void clear() { |
98 | Worklist.clear(); |
99 | WorklistMap.clear(); |
100 | } |
101 | |
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(Val: I); |
112 | return I; |
113 | } |
114 | }; |
115 | |
116 | } // end namespace llvm. |
117 | |
118 | #endif |
119 | |