1 //===- BlockFrequencyInfo.cpp - Block Frequency Analysis ------------------===// 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 // Loops should be simplified before this analysis. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Analysis/BlockFrequencyInfo.h" 15 #include "llvm/Analysis/BlockFrequencyInfoImpl.h" 16 #include "llvm/Analysis/BranchProbabilityInfo.h" 17 #include "llvm/Analysis/LoopInfo.h" 18 #include "llvm/Analysis/Passes.h" 19 #include "llvm/IR/CFG.h" 20 #include "llvm/InitializePasses.h" 21 #include "llvm/Support/CommandLine.h" 22 #include "llvm/Support/Debug.h" 23 #include "llvm/Support/GraphWriter.h" 24 25 using namespace llvm; 26 27 #define DEBUG_TYPE "block-freq" 28 29 #ifndef NDEBUG 30 enum GVDAGType { 31 GVDT_None, 32 GVDT_Fraction, 33 GVDT_Integer 34 }; 35 36 static cl::opt<GVDAGType> 37 ViewBlockFreqPropagationDAG("view-block-freq-propagation-dags", cl::Hidden, 38 cl::desc("Pop up a window to show a dag displaying how block " 39 "frequencies propagation through the CFG."), 40 cl::values( 41 clEnumValN(GVDT_None, "none", 42 "do not display graphs."), 43 clEnumValN(GVDT_Fraction, "fraction", "display a graph using the " 44 "fractional block frequency representation."), 45 clEnumValN(GVDT_Integer, "integer", "display a graph using the raw " 46 "integer fractional block frequency representation."), 47 clEnumValEnd)); 48 49 namespace llvm { 50 51 template <> 52 struct GraphTraits<BlockFrequencyInfo *> { 53 typedef const BasicBlock NodeType; 54 typedef succ_const_iterator ChildIteratorType; 55 typedef Function::const_iterator nodes_iterator; 56 57 static inline const NodeType *getEntryNode(const BlockFrequencyInfo *G) { 58 return G->getFunction()->begin(); 59 } 60 static ChildIteratorType child_begin(const NodeType *N) { 61 return succ_begin(N); 62 } 63 static ChildIteratorType child_end(const NodeType *N) { 64 return succ_end(N); 65 } 66 static nodes_iterator nodes_begin(const BlockFrequencyInfo *G) { 67 return G->getFunction()->begin(); 68 } 69 static nodes_iterator nodes_end(const BlockFrequencyInfo *G) { 70 return G->getFunction()->end(); 71 } 72 }; 73 74 template<> 75 struct DOTGraphTraits<BlockFrequencyInfo*> : public DefaultDOTGraphTraits { 76 explicit DOTGraphTraits(bool isSimple=false) : 77 DefaultDOTGraphTraits(isSimple) {} 78 79 static std::string getGraphName(const BlockFrequencyInfo *G) { 80 return G->getFunction()->getName(); 81 } 82 83 std::string getNodeLabel(const BasicBlock *Node, 84 const BlockFrequencyInfo *Graph) { 85 std::string Result; 86 raw_string_ostream OS(Result); 87 88 OS << Node->getName().str() << ":"; 89 switch (ViewBlockFreqPropagationDAG) { 90 case GVDT_Fraction: 91 Graph->printBlockFreq(OS, Node); 92 break; 93 case GVDT_Integer: 94 OS << Graph->getBlockFreq(Node).getFrequency(); 95 break; 96 case GVDT_None: 97 llvm_unreachable("If we are not supposed to render a graph we should " 98 "never reach this point."); 99 } 100 101 return Result; 102 } 103 }; 104 105 } // end namespace llvm 106 #endif 107 108 INITIALIZE_PASS_BEGIN(BlockFrequencyInfo, "block-freq", 109 "Block Frequency Analysis", true, true) 110 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo) 111 INITIALIZE_PASS_DEPENDENCY(LoopInfo) 112 INITIALIZE_PASS_END(BlockFrequencyInfo, "block-freq", 113 "Block Frequency Analysis", true, true) 114 115 char BlockFrequencyInfo::ID = 0; 116 117 118 BlockFrequencyInfo::BlockFrequencyInfo() : FunctionPass(ID) { 119 initializeBlockFrequencyInfoPass(*PassRegistry::getPassRegistry()); 120 } 121 122 BlockFrequencyInfo::~BlockFrequencyInfo() {} 123 124 void BlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const { 125 AU.addRequired<BranchProbabilityInfo>(); 126 AU.addRequired<LoopInfo>(); 127 AU.setPreservesAll(); 128 } 129 130 bool BlockFrequencyInfo::runOnFunction(Function &F) { 131 BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>(); 132 LoopInfo &LI = getAnalysis<LoopInfo>(); 133 if (!BFI) 134 BFI.reset(new ImplType); 135 BFI->doFunction(&F, &BPI, &LI); 136 #ifndef NDEBUG 137 if (ViewBlockFreqPropagationDAG != GVDT_None) 138 view(); 139 #endif 140 return false; 141 } 142 143 void BlockFrequencyInfo::releaseMemory() { BFI.reset(); } 144 145 void BlockFrequencyInfo::print(raw_ostream &O, const Module *) const { 146 if (BFI) BFI->print(O); 147 } 148 149 BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const { 150 return BFI ? BFI->getBlockFreq(BB) : 0; 151 } 152 153 /// Pop up a ghostview window with the current block frequency propagation 154 /// rendered using dot. 155 void BlockFrequencyInfo::view() const { 156 // This code is only for debugging. 157 #ifndef NDEBUG 158 ViewGraph(const_cast<BlockFrequencyInfo *>(this), "BlockFrequencyDAGs"); 159 #else 160 errs() << "BlockFrequencyInfo::view is only available in debug builds on " 161 "systems with Graphviz or gv!\n"; 162 #endif // NDEBUG 163 } 164 165 const Function *BlockFrequencyInfo::getFunction() const { 166 return BFI ? BFI->getFunction() : nullptr; 167 } 168 169 raw_ostream &BlockFrequencyInfo:: 170 printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const { 171 return BFI ? BFI->printBlockFreq(OS, Freq) : OS; 172 } 173 174 raw_ostream & 175 BlockFrequencyInfo::printBlockFreq(raw_ostream &OS, 176 const BasicBlock *BB) const { 177 return BFI ? BFI->printBlockFreq(OS, BB) : OS; 178 } 179 180 uint64_t BlockFrequencyInfo::getEntryFreq() const { 181 return BFI ? BFI->getEntryFreq() : 0; 182 } 183
