1 | //===- DataflowWorklist.h ---------------------------------------*- 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 | // A simple and reusable worklist for flow-sensitive analyses. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | #ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_DATAFLOWWORKLIST_H |
13 | #define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_DATAFLOWWORKLIST_H |
14 | |
15 | #include "clang/Analysis/Analyses/IntervalPartition.h" |
16 | #include "clang/Analysis/Analyses/PostOrderCFGView.h" |
17 | #include "clang/Analysis/CFG.h" |
18 | #include "llvm/ADT/PriorityQueue.h" |
19 | |
20 | namespace clang { |
21 | /// A worklist implementation where the enqueued blocks will be dequeued based |
22 | /// on the order defined by 'Comp'. |
23 | template <typename Comp, unsigned QueueSize> class DataflowWorklistBase { |
24 | llvm::BitVector EnqueuedBlocks; |
25 | llvm::PriorityQueue<const CFGBlock *, |
26 | SmallVector<const CFGBlock *, QueueSize>, Comp> |
27 | WorkList; |
28 | |
29 | public: |
30 | DataflowWorklistBase(const CFG &Cfg, Comp C) |
31 | : EnqueuedBlocks(Cfg.getNumBlockIDs()), WorkList(C) {} |
32 | |
33 | void enqueueBlock(const CFGBlock *Block) { |
34 | if (Block && !EnqueuedBlocks[Block->getBlockID()]) { |
35 | EnqueuedBlocks[Block->getBlockID()] = true; |
36 | WorkList.push(Block); |
37 | } |
38 | } |
39 | |
40 | const CFGBlock *dequeue() { |
41 | if (WorkList.empty()) |
42 | return nullptr; |
43 | const CFGBlock *B = WorkList.top(); |
44 | WorkList.pop(); |
45 | EnqueuedBlocks[B->getBlockID()] = false; |
46 | return B; |
47 | } |
48 | }; |
49 | |
50 | struct ReversePostOrderCompare { |
51 | PostOrderCFGView::BlockOrderCompare Cmp; |
52 | bool operator()(const CFGBlock *lhs, const CFGBlock *rhs) const { |
53 | return Cmp(rhs, lhs); |
54 | } |
55 | }; |
56 | |
57 | /// A worklist implementation for forward dataflow analysis. The enqueued |
58 | /// blocks will be dequeued in reverse post order. The worklist cannot contain |
59 | /// the same block multiple times at once. |
60 | struct ForwardDataflowWorklist |
61 | : DataflowWorklistBase<ReversePostOrderCompare, 20> { |
62 | ForwardDataflowWorklist(const CFG &Cfg, PostOrderCFGView *POV) |
63 | : DataflowWorklistBase(Cfg, |
64 | ReversePostOrderCompare{.Cmp: POV->getComparator()}) {} |
65 | |
66 | ForwardDataflowWorklist(const CFG &Cfg, AnalysisDeclContext &Ctx) |
67 | : ForwardDataflowWorklist(Cfg, Ctx.getAnalysis<PostOrderCFGView>()) {} |
68 | |
69 | void enqueueSuccessors(const CFGBlock *Block) { |
70 | for (auto B : Block->succs()) |
71 | enqueueBlock(Block: B); |
72 | } |
73 | }; |
74 | |
75 | /// A worklist implementation for forward dataflow analysis based on a weak |
76 | /// topological ordering of the nodes. The worklist cannot contain the same |
77 | /// block multiple times at once. |
78 | struct WTODataflowWorklist : DataflowWorklistBase<WTOCompare, 20> { |
79 | WTODataflowWorklist(const CFG &Cfg, const WTOCompare &Cmp) |
80 | : DataflowWorklistBase(Cfg, Cmp) {} |
81 | |
82 | void enqueueSuccessors(const CFGBlock *Block) { |
83 | for (auto B : Block->succs()) |
84 | enqueueBlock(Block: B); |
85 | } |
86 | }; |
87 | |
88 | /// A worklist implementation for backward dataflow analysis. The enqueued |
89 | /// block will be dequeued in post order. The worklist cannot contain the same |
90 | /// block multiple times at once. |
91 | struct BackwardDataflowWorklist |
92 | : DataflowWorklistBase<PostOrderCFGView::BlockOrderCompare, 20> { |
93 | BackwardDataflowWorklist(const CFG &Cfg, AnalysisDeclContext &Ctx) |
94 | : DataflowWorklistBase( |
95 | Cfg, Ctx.getAnalysis<PostOrderCFGView>()->getComparator()) {} |
96 | |
97 | void enqueuePredecessors(const CFGBlock *Block) { |
98 | for (auto B : Block->preds()) |
99 | enqueueBlock(Block: B); |
100 | } |
101 | }; |
102 | |
103 | } // namespace clang |
104 | |
105 | #endif // LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_DATAFLOWWORKLIST_H |
106 | |