1//===- llvm/Analysis/DominanceFrontier.h - Dominator Frontiers --*- 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// This file defines the DominanceFrontier class, which calculate and holds the
10// dominance frontier for a function.
11//
12// This should be considered deprecated, don't add any more uses of this data
13// structure.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_ANALYSIS_DOMINANCEFRONTIER_H
18#define LLVM_ANALYSIS_DOMINANCEFRONTIER_H
19
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/GraphTraits.h"
22#include "llvm/ADT/SetVector.h"
23#include "llvm/Config/llvm-config.h"
24#include "llvm/IR/PassManager.h"
25#include "llvm/Pass.h"
26#include "llvm/Support/GenericDomTree.h"
27#include <cassert>
28#include <utility>
29
30namespace llvm {
31
32class Function;
33class raw_ostream;
34
35//===----------------------------------------------------------------------===//
36/// DominanceFrontierBase - Common base class for computing forward and inverse
37/// dominance frontiers for a function.
38///
39template <class BlockT, bool IsPostDom>
40class DominanceFrontierBase {
41public:
42 // Dom set for a bb. Use SetVector to make iterating dom frontiers of a bb
43 // deterministic.
44 using DomSetType = SetVector<BlockT *>;
45 using DomSetMapType = DenseMap<BlockT *, DomSetType>; // Dom set map
46
47protected:
48 using BlockTraits = GraphTraits<BlockT *>;
49
50 DomSetMapType Frontiers;
51 // Postdominators can have multiple roots.
52 SmallVector<BlockT *, IsPostDom ? 4 : 1> Roots;
53 static constexpr bool IsPostDominators = IsPostDom;
54
55public:
56 DominanceFrontierBase() = default;
57
58 /// getRoots - Return the root blocks of the current CFG. This may include
59 /// multiple blocks if we are computing post dominators. For forward
60 /// dominators, this will always be a single block (the entry node).
61 const SmallVectorImpl<BlockT *> &getRoots() const { return Roots; }
62
63 BlockT *getRoot() const {
64 assert(Roots.size() == 1 && "Should always have entry node!");
65 return Roots[0];
66 }
67
68 /// isPostDominator - Returns true if analysis based of postdoms
69 bool isPostDominator() const {
70 return IsPostDominators;
71 }
72
73 void releaseMemory() {
74 Frontiers.clear();
75 }
76
77 // Accessor interface:
78 using iterator = typename DomSetMapType::iterator;
79 using const_iterator = typename DomSetMapType::const_iterator;
80
81 iterator begin() { return Frontiers.begin(); }
82 const_iterator begin() const { return Frontiers.begin(); }
83 iterator end() { return Frontiers.end(); }
84 const_iterator end() const { return Frontiers.end(); }
85 iterator find(BlockT *B) { return Frontiers.find(B); }
86 const_iterator find(BlockT *B) const { return Frontiers.find(B); }
87
88 iterator addBasicBlock(BlockT *BB, const DomSetType &frontier) {
89 assert(find(BB) == end() && "Block already in DominanceFrontier!");
90 return Frontiers.insert(std::make_pair(BB, frontier)).first;
91 }
92
93 /// removeBlock - Remove basic block BB's frontier.
94 void removeBlock(BlockT *BB);
95
96 void addToFrontier(iterator I, BlockT *Node);
97
98 void removeFromFrontier(iterator I, BlockT *Node);
99
100 /// compareDomSet - Return false if two domsets match. Otherwise
101 /// return true;
102 bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const;
103
104 /// compare - Return true if the other dominance frontier base matches
105 /// this dominance frontier base. Otherwise return false.
106 bool compare(DominanceFrontierBase &Other) const;
107
108 /// print - Convert to human readable form
109 ///
110 void print(raw_ostream &OS) const;
111
112 /// dump - Dump the dominance frontier to dbgs().
113#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
114 void dump() const;
115#endif
116};
117
118//===-------------------------------------
119/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
120/// used to compute a forward dominator frontiers.
121///
122template <class BlockT>
123class ForwardDominanceFrontierBase
124 : public DominanceFrontierBase<BlockT, false> {
125private:
126 using BlockTraits = GraphTraits<BlockT *>;
127
128public:
129 using DomTreeT = DomTreeBase<BlockT>;
130 using DomTreeNodeT = DomTreeNodeBase<BlockT>;
131 using DomSetType = typename DominanceFrontierBase<BlockT, false>::DomSetType;
132
133 void analyze(DomTreeT &DT) {
134 assert(DT.root_size() == 1 &&
135 "Only one entry block for forward domfronts!");
136 this->Roots = {DT.getRoot()};
137 calculate(DT, Node: DT[this->Roots[0]]);
138 }
139
140 const DomSetType &calculate(const DomTreeT &DT, const DomTreeNodeT *Node);
141};
142
143class DominanceFrontier : public ForwardDominanceFrontierBase<BasicBlock> {
144public:
145 using DomTreeT = DomTreeBase<BasicBlock>;
146 using DomTreeNodeT = DomTreeNodeBase<BasicBlock>;
147 using DomSetType = DominanceFrontierBase<BasicBlock, false>::DomSetType;
148 using iterator = DominanceFrontierBase<BasicBlock, false>::iterator;
149 using const_iterator =
150 DominanceFrontierBase<BasicBlock, false>::const_iterator;
151
152 /// Handle invalidation explicitly.
153 bool invalidate(Function &F, const PreservedAnalyses &PA,
154 FunctionAnalysisManager::Invalidator &);
155};
156
157class DominanceFrontierWrapperPass : public FunctionPass {
158 DominanceFrontier DF;
159
160public:
161 static char ID; // Pass ID, replacement for typeid
162
163 DominanceFrontierWrapperPass();
164
165 DominanceFrontier &getDominanceFrontier() { return DF; }
166 const DominanceFrontier &getDominanceFrontier() const { return DF; }
167
168 void releaseMemory() override;
169
170 bool runOnFunction(Function &) override;
171
172 void getAnalysisUsage(AnalysisUsage &AU) const override;
173
174 void print(raw_ostream &OS, const Module * = nullptr) const override;
175
176 void dump() const;
177};
178
179extern template class DominanceFrontierBase<BasicBlock, false>;
180extern template class DominanceFrontierBase<BasicBlock, true>;
181extern template class ForwardDominanceFrontierBase<BasicBlock>;
182
183/// Analysis pass which computes a \c DominanceFrontier.
184class DominanceFrontierAnalysis
185 : public AnalysisInfoMixin<DominanceFrontierAnalysis> {
186 friend AnalysisInfoMixin<DominanceFrontierAnalysis>;
187
188 static AnalysisKey Key;
189
190public:
191 /// Provide the result type for this analysis pass.
192 using Result = DominanceFrontier;
193
194 /// Run the analysis pass over a function and produce a dominator tree.
195 DominanceFrontier run(Function &F, FunctionAnalysisManager &AM);
196};
197
198/// Printer pass for the \c DominanceFrontier.
199class DominanceFrontierPrinterPass
200 : public PassInfoMixin<DominanceFrontierPrinterPass> {
201 raw_ostream &OS;
202
203public:
204 explicit DominanceFrontierPrinterPass(raw_ostream &OS);
205
206 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
207
208 static bool isRequired() { return true; }
209};
210
211} // end namespace llvm
212
213#endif // LLVM_ANALYSIS_DOMINANCEFRONTIER_H
214

source code of llvm/include/llvm/Analysis/DominanceFrontier.h