1//===- Dominators.h - Dominator Info Calculation ----------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the DominatorTree class, which provides fast and efficient
11// dominance queries.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_IR_DOMINATORS_H
16#define LLVM_IR_DOMINATORS_H
17
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/DepthFirstIterator.h"
20#include "llvm/ADT/GraphTraits.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/IR/BasicBlock.h"
24#include "llvm/IR/CFG.h"
25#include "llvm/IR/Function.h"
26#include "llvm/Pass.h"
27#include "llvm/Support/Compiler.h"
28#include "llvm/Support/GenericDomTree.h"
29#include "llvm/Support/raw_ostream.h"
30#include <algorithm>
31
32namespace llvm {
33
34// FIXME: Replace this brittle forward declaration with the include of the new
35// PassManager.h when doing so doesn't break the PassManagerBuilder.
36template <typename IRUnitT> class AnalysisManager;
37class PreservedAnalyses;
38
39EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
40EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
41
42#define LLVM_COMMA ,
43EXTERN_TEMPLATE_INSTANTIATION(void Calculate<Function LLVM_COMMA BasicBlock *>(
44    DominatorTreeBase<GraphTraits<BasicBlock *>::NodeType> &DT LLVM_COMMA
45        Function &F));
46EXTERN_TEMPLATE_INSTANTIATION(
47    void Calculate<Function LLVM_COMMA Inverse<BasicBlock *> >(
48        DominatorTreeBase<GraphTraits<Inverse<BasicBlock *> >::NodeType> &DT
49            LLVM_COMMA Function &F));
50#undef LLVM_COMMA
51
52typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
53
54class BasicBlockEdge {
55  const BasicBlock *Start;
56  const BasicBlock *End;
57public:
58  BasicBlockEdge(const BasicBlock *Start_, const BasicBlock *End_) :
59    Start(Start_), End(End_) { }
60  const BasicBlock *getStart() const {
61    return Start;
62  }
63  const BasicBlock *getEnd() const {
64    return End;
65  }
66  bool isSingleEdge() const;
67};
68
69/// \brief Concrete subclass of DominatorTreeBase that is used to compute a
70/// normal dominator tree.
71class DominatorTree : public DominatorTreeBase<BasicBlock> {
72public:
73  typedef DominatorTreeBase<BasicBlock> Base;
74
75  DominatorTree() : DominatorTreeBase<BasicBlock>(false) {}
76
77  DominatorTree(DominatorTree &&Arg)
78      : Base(std::move(static_cast<Base &>(Arg))) {}
79  DominatorTree &operator=(DominatorTree &&RHS) {
80    Base::operator=(std::move(static_cast<Base &>(RHS)));
81    return *this;
82  }
83
84  /// \brief Returns *false* if the other dominator tree matches this dominator
85  /// tree.
86  inline bool compare(const DominatorTree &Other) const {
87    const DomTreeNode *R = getRootNode();
88    const DomTreeNode *OtherR = Other.getRootNode();
89
90    if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
91      return true;
92
93    if (Base::compare(Other))
94      return true;
95
96    return false;
97  }
98
99  // Ensure base-class overloads are visible.
100  using Base::dominates;
101
102  /// \brief Return true if Def dominates a use in User.
103  ///
104  /// This performs the special checks necessary if Def and User are in the same
105  /// basic block. Note that Def doesn't dominate a use in Def itself!
106  bool dominates(const Instruction *Def, const Use &U) const;
107  bool dominates(const Instruction *Def, const Instruction *User) const;
108  bool dominates(const Instruction *Def, const BasicBlock *BB) const;
109  bool dominates(const BasicBlockEdge &BBE, const Use &U) const;
110  bool dominates(const BasicBlockEdge &BBE, const BasicBlock *BB) const;
111
112  // Ensure base class overloads are visible.
113  using Base::isReachableFromEntry;
114
115  /// \brief Provide an overload for a Use.
116  bool isReachableFromEntry(const Use &U) const;
117
118  /// \brief Verify the correctness of the domtree by re-computing it.
119  ///
120  /// This should only be used for debugging as it aborts the program if the
121  /// verification fails.
122  void verifyDomTree() const;
123};
124
125//===-------------------------------------
126// DominatorTree GraphTraits specializations so the DominatorTree can be
127// iterable by generic graph iterators.
128
129template <> struct GraphTraits<DomTreeNode*> {
130  typedef DomTreeNode NodeType;
131  typedef NodeType::iterator  ChildIteratorType;
132
133  static NodeType *getEntryNode(NodeType *N) {
134    return N;
135  }
136  static inline ChildIteratorType child_begin(NodeType *N) {
137    return N->begin();
138  }
139  static inline ChildIteratorType child_end(NodeType *N) {
140    return N->end();
141  }
142
143  typedef df_iterator<DomTreeNode*> nodes_iterator;
144
145  static nodes_iterator nodes_begin(DomTreeNode *N) {
146    return df_begin(getEntryNode(N));
147  }
148
149  static nodes_iterator nodes_end(DomTreeNode *N) {
150    return df_end(getEntryNode(N));
151  }
152};
153
154template <> struct GraphTraits<DominatorTree*>
155  : public GraphTraits<DomTreeNode*> {
156  static NodeType *getEntryNode(DominatorTree *DT) {
157    return DT->getRootNode();
158  }
159
160  static nodes_iterator nodes_begin(DominatorTree *N) {
161    return df_begin(getEntryNode(N));
162  }
163
164  static nodes_iterator nodes_end(DominatorTree *N) {
165    return df_end(getEntryNode(N));
166  }
167};
168
169/// \brief Analysis pass which computes a \c DominatorTree.
170class DominatorTreeAnalysis {
171public:
172  /// \brief Provide the result typedef for this analysis pass.
173  typedef DominatorTree Result;
174
175  /// \brief Opaque, unique identifier for this analysis pass.
176  static void *ID() { return (void *)&PassID; }
177
178  /// \brief Run the analysis pass over a function and produce a dominator tree.
179  DominatorTree run(Function &F);
180
181  /// \brief Provide access to a name for this pass for debugging purposes.
182  static StringRef name() { return "DominatorTreeAnalysis"; }
183
184private:
185  static char PassID;
186};
187
188/// \brief Printer pass for the \c DominatorTree.
189class DominatorTreePrinterPass {
190  raw_ostream &OS;
191
192public:
193  explicit DominatorTreePrinterPass(raw_ostream &OS);
194  PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
195
196  static StringRef name() { return "DominatorTreePrinterPass"; }
197};
198
199/// \brief Verifier pass for the \c DominatorTree.
200struct DominatorTreeVerifierPass {
201  PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
202
203  static StringRef name() { return "DominatorTreeVerifierPass"; }
204};
205
206/// \brief Legacy analysis pass which computes a \c DominatorTree.
207class DominatorTreeWrapperPass : public FunctionPass {
208  DominatorTree DT;
209
210public:
211  static char ID;
212
213  DominatorTreeWrapperPass() : FunctionPass(ID) {
214    initializeDominatorTreeWrapperPassPass(*PassRegistry::getPassRegistry());
215  }
216
217  DominatorTree &getDomTree() { return DT; }
218  const DominatorTree &getDomTree() const { return DT; }
219
220  bool runOnFunction(Function &F) override;
221
222  void verifyAnalysis() const override;
223
224  void getAnalysisUsage(AnalysisUsage &AU) const override {
225    AU.setPreservesAll();
226  }
227
228  void releaseMemory() override { DT.releaseMemory(); }
229
230  void print(raw_ostream &OS, const Module *M = nullptr) const override;
231};
232
233} // End llvm namespace
234
235#endif
236