1 //===- PostOrderCFGView.h - Post order view of CFG blocks ---------*- 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 implements post order view of the blocks in a CFG. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_POSTORDER_CFGVIEW 15 #define LLVM_CLANG_POSTORDER_CFGVIEW 16 17 #include <vector> 18 //#include <algorithm> 19 20 #include "llvm/ADT/PostOrderIterator.h" 21 #include "llvm/ADT/DenseMap.h" 22 #include "llvm/ADT/BitVector.h" 23 24 #include "clang/Analysis/AnalysisContext.h" 25 #include "clang/Analysis/CFG.h" 26 27 namespace clang { 28 29 class PostOrderCFGView : public ManagedAnalysis { 30 virtual void anchor(); 31 public: 32 /// \brief Implements a set of CFGBlocks using a BitVector. 33 /// 34 /// This class contains a minimal interface, primarily dictated by the SetType 35 /// template parameter of the llvm::po_iterator template, as used with 36 /// external storage. We also use this set to keep track of which CFGBlocks we 37 /// visit during the analysis. 38 class CFGBlockSet { 39 llvm::BitVector VisitedBlockIDs; 40 public: 41 // po_iterator requires this iterator, but the only interface needed is the 42 // value_type typedef. 43 struct iterator { typedef const CFGBlock *value_type; }; 44 CFGBlockSet()45 CFGBlockSet() {} CFGBlockSet(const CFG * G)46 CFGBlockSet(const CFG *G) : VisitedBlockIDs(G->getNumBlockIDs(), false) {} 47 48 /// \brief Set the bit associated with a particular CFGBlock. 49 /// This is the important method for the SetType template parameter. insert(const CFGBlock * Block)50 bool insert(const CFGBlock *Block) { 51 // Note that insert() is called by po_iterator, which doesn't check to 52 // make sure that Block is non-null. Moreover, the CFGBlock iterator will 53 // occasionally hand out null pointers for pruned edges, so we catch those 54 // here. 55 if (Block == 0) 56 return false; // if an edge is trivially false. 57 if (VisitedBlockIDs.test(Block->getBlockID())) 58 return false; 59 VisitedBlockIDs.set(Block->getBlockID()); 60 return true; 61 } 62 63 /// \brief Check if the bit for a CFGBlock has been already set. 64 /// This method is for tracking visited blocks in the main threadsafety 65 /// loop. Block must not be null. alreadySet(const CFGBlock * Block)66 bool alreadySet(const CFGBlock *Block) { 67 return VisitedBlockIDs.test(Block->getBlockID()); 68 } 69 }; 70 71 private: 72 typedef llvm::po_iterator<const CFG*, CFGBlockSet, true> po_iterator; 73 std::vector<const CFGBlock*> Blocks; 74 75 typedef llvm::DenseMap<const CFGBlock *, unsigned> BlockOrderTy; 76 BlockOrderTy BlockOrder; 77 78 public: 79 typedef std::vector<const CFGBlock*>::reverse_iterator iterator; 80 81 PostOrderCFGView(const CFG *cfg); 82 begin()83 iterator begin() { return Blocks.rbegin(); } end()84 iterator end() { return Blocks.rend(); } 85 empty()86 bool empty() { return begin() == end(); } 87 88 struct BlockOrderCompare; 89 friend struct BlockOrderCompare; 90 91 struct BlockOrderCompare { 92 const PostOrderCFGView &POV; 93 public: BlockOrderCompareBlockOrderCompare94 BlockOrderCompare(const PostOrderCFGView &pov) : POV(pov) {} 95 bool operator()(const CFGBlock *b1, const CFGBlock *b2) const; 96 }; 97 getComparator()98 BlockOrderCompare getComparator() const { 99 return BlockOrderCompare(*this); 100 } 101 102 // Used by AnalyisContext to construct this object. 103 static const void *getTag(); 104 105 static PostOrderCFGView *create(AnalysisDeclContext &analysisContext); 106 }; 107 108 } // end clang namespace 109 110 #endif 111 112