src/llvm/include/llvm/IR/Dominators.h

   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
  32 namespace 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.
  36 template <typename IRUnitT> class AnalysisManager;
  37 class PreservedAnalyses;
  38
  39 EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
  40 EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
  41
  42 #define LLVM_COMMA ,
  43 EXTERN_TEMPLATE_INSTANTIATION(void Calculate<Function LLVM_COMMA BasicBlock *>(
  44     DominatorTreeBase<GraphTraits<BasicBlock *>::NodeType> &DT LLVM_COMMA
  45         Function &F));
  46 EXTERN_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
  52 typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
  53
  54 class BasicBlockEdge {
  55   const BasicBlock *Start;
  56   const BasicBlock *End;
  57 public:
  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.
  71 class DominatorTree : public DominatorTreeBase<BasicBlock> {
  72 public:
  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
 129 template <> 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
 154 template <> 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.
 170 class DominatorTreeAnalysis {
 171 public:
 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
 184 private:
 185   static char PassID;
 186 };
 187
 188 /// \brief Printer pass for the \c DominatorTree.
 189 class DominatorTreePrinterPass {
 190   raw_ostream &OS;
 191
 192 public:
 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.
 200 struct 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.
 207 class DominatorTreeWrapperPass : public FunctionPass {
 208   DominatorTree DT;
 209
 210 public:
 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