| //===- Dominators.h - Dominator Info Calculation ----------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines the DominatorTree class, which provides fast and efficient |
| // dominance queries. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_IR_DOMINATORS_H |
| #define LLVM_IR_DOMINATORS_H |
| |
| #include "llvm/ADT/DenseMapInfo.h" |
| #include "llvm/ADT/DepthFirstIterator.h" |
| #include "llvm/ADT/GraphTraits.h" |
| #include "llvm/ADT/Hashing.h" |
| #include "llvm/IR/BasicBlock.h" |
| #include "llvm/IR/CFG.h" |
| #include "llvm/IR/PassManager.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/GenericDomTree.h" |
| #include <utility> |
| |
| namespace llvm { |
| |
| class Function; |
| class Instruction; |
| class Module; |
| class raw_ostream; |
| |
| extern template class DomTreeNodeBase<BasicBlock>; |
| extern template class DominatorTreeBase<BasicBlock>; |
| |
| extern template void Calculate<Function, BasicBlock *>( |
| DominatorTreeBaseByGraphTraits<GraphTraits<BasicBlock *>> &DT, Function &F); |
| extern template void Calculate<Function, Inverse<BasicBlock *>>( |
| DominatorTreeBaseByGraphTraits<GraphTraits<Inverse<BasicBlock *>>> &DT, |
| Function &F); |
| |
| using DomTreeNode = DomTreeNodeBase<BasicBlock>; |
| |
| class BasicBlockEdge { |
| const BasicBlock *Start; |
| const BasicBlock *End; |
| |
| public: |
| BasicBlockEdge(const BasicBlock *Start_, const BasicBlock *End_) : |
| Start(Start_), End(End_) {} |
| |
| BasicBlockEdge(const std::pair<BasicBlock *, BasicBlock *> &Pair) |
| : Start(Pair.first), End(Pair.second) {} |
| |
| BasicBlockEdge(const std::pair<const BasicBlock *, const BasicBlock *> &Pair) |
| : Start(Pair.first), End(Pair.second) {} |
| |
| const BasicBlock *getStart() const { |
| return Start; |
| } |
| |
| const BasicBlock *getEnd() const { |
| return End; |
| } |
| |
| /// Check if this is the only edge between Start and End. |
| bool isSingleEdge() const; |
| }; |
| |
| template <> struct DenseMapInfo<BasicBlockEdge> { |
| using BBInfo = DenseMapInfo<const BasicBlock *>; |
| |
| static unsigned getHashValue(const BasicBlockEdge *V); |
| |
| static inline BasicBlockEdge getEmptyKey() { |
| return BasicBlockEdge(BBInfo::getEmptyKey(), BBInfo::getEmptyKey()); |
| } |
| |
| static inline BasicBlockEdge getTombstoneKey() { |
| return BasicBlockEdge(BBInfo::getTombstoneKey(), BBInfo::getTombstoneKey()); |
| } |
| |
| static unsigned getHashValue(const BasicBlockEdge &Edge) { |
| return hash_combine(BBInfo::getHashValue(Edge.getStart()), |
| BBInfo::getHashValue(Edge.getEnd())); |
| } |
| |
| static bool isEqual(const BasicBlockEdge &LHS, const BasicBlockEdge &RHS) { |
| return BBInfo::isEqual(LHS.getStart(), RHS.getStart()) && |
| BBInfo::isEqual(LHS.getEnd(), RHS.getEnd()); |
| } |
| }; |
| |
| /// \brief Concrete subclass of DominatorTreeBase that is used to compute a |
| /// normal dominator tree. |
| /// |
| /// Definition: A block is said to be forward statically reachable if there is |
| /// a path from the entry of the function to the block. A statically reachable |
| /// block may become statically unreachable during optimization. |
| /// |
| /// A forward unreachable block may appear in the dominator tree, or it may |
| /// not. If it does, dominance queries will return results as if all reachable |
| /// blocks dominate it. When asking for a Node corresponding to a potentially |
| /// unreachable block, calling code must handle the case where the block was |
| /// unreachable and the result of getNode() is nullptr. |
| /// |
| /// Generally, a block known to be unreachable when the dominator tree is |
| /// constructed will not be in the tree. One which becomes unreachable after |
| /// the dominator tree is initially constructed may still exist in the tree, |
| /// even if the tree is properly updated. Calling code should not rely on the |
| /// preceding statements; this is stated only to assist human understanding. |
| class DominatorTree : public DominatorTreeBase<BasicBlock> { |
| public: |
| using Base = DominatorTreeBase<BasicBlock>; |
| |
| DominatorTree() : DominatorTreeBase<BasicBlock>(false) {} |
| explicit DominatorTree(Function &F) : DominatorTreeBase<BasicBlock>(false) { |
| recalculate(F); |
| } |
| |
| /// Handle invalidation explicitly. |
| bool invalidate(Function &F, const PreservedAnalyses &PA, |
| FunctionAnalysisManager::Invalidator &); |
| |
| /// \brief Returns *false* if the other dominator tree matches this dominator |
| /// tree. |
| inline bool compare(const DominatorTree &Other) const { |
| const DomTreeNode *R = getRootNode(); |
| const DomTreeNode *OtherR = Other.getRootNode(); |
| return !R || !OtherR || R->getBlock() != OtherR->getBlock() || |
| Base::compare(Other); |
| } |
| |
| // Ensure base-class overloads are visible. |
| using Base::dominates; |
| |
| /// \brief Return true if Def dominates a use in User. |
| /// |
| /// This performs the special checks necessary if Def and User are in the same |
| /// basic block. Note that Def doesn't dominate a use in Def itself! |
| bool dominates(const Instruction *Def, const Use &U) const; |
| bool dominates(const Instruction *Def, const Instruction *User) const; |
| bool dominates(const Instruction *Def, const BasicBlock *BB) const; |
| |
| /// Return true if an edge dominates a use. |
| /// |
| /// If BBE is not a unique edge between start and end of the edge, it can |
| /// never dominate the use. |
| bool dominates(const BasicBlockEdge &BBE, const Use &U) const; |
| bool dominates(const BasicBlockEdge &BBE, const BasicBlock *BB) const; |
| |
| // Ensure base class overloads are visible. |
| using Base::isReachableFromEntry; |
| |
| /// \brief Provide an overload for a Use. |
| bool isReachableFromEntry(const Use &U) const; |
| |
| /// \brief Verify the correctness of the domtree by re-computing it. |
| /// |
| /// This should only be used for debugging as it aborts the program if the |
| /// verification fails. |
| void verifyDomTree() const; |
| |
| // Pop up a GraphViz/gv window with the Dominator Tree rendered using `dot`. |
| void viewGraph(const Twine &Name, const Twine &Title); |
| void viewGraph(); |
| }; |
| |
| //===------------------------------------- |
| // DominatorTree GraphTraits specializations so the DominatorTree can be |
| // iterable by generic graph iterators. |
| |
| template <class Node, class ChildIterator> struct DomTreeGraphTraitsBase { |
| using NodeRef = Node *; |
| using ChildIteratorType = ChildIterator; |
| using nodes_iterator = df_iterator<Node *, df_iterator_default_set<Node*>>; |
| |
| static NodeRef getEntryNode(NodeRef N) { return N; } |
| static ChildIteratorType child_begin(NodeRef N) { return N->begin(); } |
| static ChildIteratorType child_end(NodeRef N) { return N->end(); } |
| |
| static nodes_iterator nodes_begin(NodeRef N) { |
| return df_begin(getEntryNode(N)); |
| } |
| |
| static nodes_iterator nodes_end(NodeRef N) { return df_end(getEntryNode(N)); } |
| }; |
| |
| template <> |
| struct GraphTraits<DomTreeNode *> |
| : public DomTreeGraphTraitsBase<DomTreeNode, DomTreeNode::iterator> {}; |
| |
| template <> |
| struct GraphTraits<const DomTreeNode *> |
| : public DomTreeGraphTraitsBase<const DomTreeNode, |
| DomTreeNode::const_iterator> {}; |
| |
| template <> struct GraphTraits<DominatorTree*> |
| : public GraphTraits<DomTreeNode*> { |
| static NodeRef getEntryNode(DominatorTree *DT) { return DT->getRootNode(); } |
| |
| static nodes_iterator nodes_begin(DominatorTree *N) { |
| return df_begin(getEntryNode(N)); |
| } |
| |
| static nodes_iterator nodes_end(DominatorTree *N) { |
| return df_end(getEntryNode(N)); |
| } |
| }; |
| |
| /// \brief Analysis pass which computes a \c DominatorTree. |
| class DominatorTreeAnalysis : public AnalysisInfoMixin<DominatorTreeAnalysis> { |
| friend AnalysisInfoMixin<DominatorTreeAnalysis>; |
| static AnalysisKey Key; |
| |
| public: |
| /// \brief Provide the result typedef for this analysis pass. |
| using Result = DominatorTree; |
| |
| /// \brief Run the analysis pass over a function and produce a dominator tree. |
| DominatorTree run(Function &F, FunctionAnalysisManager &); |
| }; |
| |
| /// \brief Printer pass for the \c DominatorTree. |
| class DominatorTreePrinterPass |
| : public PassInfoMixin<DominatorTreePrinterPass> { |
| raw_ostream &OS; |
| |
| public: |
| explicit DominatorTreePrinterPass(raw_ostream &OS); |
| |
| PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| /// \brief Verifier pass for the \c DominatorTree. |
| struct DominatorTreeVerifierPass : PassInfoMixin<DominatorTreeVerifierPass> { |
| PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); |
| }; |
| |
| /// \brief Legacy analysis pass which computes a \c DominatorTree. |
| class DominatorTreeWrapperPass : public FunctionPass { |
| DominatorTree DT; |
| |
| public: |
| static char ID; |
| |
| DominatorTreeWrapperPass() : FunctionPass(ID) { |
| initializeDominatorTreeWrapperPassPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| DominatorTree &getDomTree() { return DT; } |
| const DominatorTree &getDomTree() const { return DT; } |
| |
| bool runOnFunction(Function &F) override; |
| |
| void verifyAnalysis() const override; |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.setPreservesAll(); |
| } |
| |
| void releaseMemory() override { DT.releaseMemory(); } |
| |
| void print(raw_ostream &OS, const Module *M = nullptr) const override; |
| }; |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_IR_DOMINATORS_H |