lib/CodeGen/MachineBlockFrequencyInfo.cpp

   1 //===- MachineBlockFrequencyInfo.cpp - MBB 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/CodeGen/MachineBlockFrequencyInfo.h"
  15 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
  16 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
  17 #include "llvm/CodeGen/MachineFunction.h"
  18 #include "llvm/CodeGen/MachineLoopInfo.h"
  19 #include "llvm/CodeGen/Passes.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 ViewMachineBlockFreqPropagationDAG("view-machine-block-freq-propagation-dags",
  38                                    cl::Hidden,
  39           cl::desc("Pop up a window to show a dag displaying how machine block "
  40                    "frequencies propagate through the CFG."),
  41           cl::values(
  42             clEnumValN(GVDT_None, "none",
  43                        "do not display graphs."),
  44             clEnumValN(GVDT_Fraction, "fraction", "display a graph using the "
  45                        "fractional block frequency representation."),
  46             clEnumValN(GVDT_Integer, "integer", "display a graph using the raw "
  47                        "integer fractional block frequency representation."),
  48             clEnumValEnd));
  49
  50 namespace llvm {
  51
  52 template <>
  53 struct GraphTraits<MachineBlockFrequencyInfo *> {
  54   typedef const MachineBasicBlock NodeType;
  55   typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
  56   typedef MachineFunction::const_iterator nodes_iterator;
  57
  58   static inline
  59   const NodeType *getEntryNode(const MachineBlockFrequencyInfo *G) {
  60     return G->getFunction()->begin();
  61   }
  62
  63   static ChildIteratorType child_begin(const NodeType *N) {
  64     return N->succ_begin();
  65   }
  66
  67   static ChildIteratorType child_end(const NodeType *N) {
  68     return N->succ_end();
  69   }
  70
  71   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
  72     return G->getFunction()->begin();
  73   }
  74
  75   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
  76     return G->getFunction()->end();
  77   }
  78 };
  79
  80 template<>
  81 struct DOTGraphTraits<MachineBlockFrequencyInfo*> :
  82     public DefaultDOTGraphTraits {
  83   explicit DOTGraphTraits(bool isSimple=false) :
  84     DefaultDOTGraphTraits(isSimple) {}
  85
  86   static std::string getGraphName(const MachineBlockFrequencyInfo *G) {
  87     return G->getFunction()->getName();
  88   }
  89
  90   std::string getNodeLabel(const MachineBasicBlock *Node,
  91                            const MachineBlockFrequencyInfo *Graph) {
  92     std::string Result;
  93     raw_string_ostream OS(Result);
  94
  95     OS << Node->getName().str() << ":";
  96     switch (ViewMachineBlockFreqPropagationDAG) {
  97     case GVDT_Fraction:
  98       Graph->printBlockFreq(OS, Node);
  99       break;
 100     case GVDT_Integer:
 101       OS << Graph->getBlockFreq(Node).getFrequency();
 102       break;
 103     case GVDT_None:
 104       llvm_unreachable("If we are not supposed to render a graph we should "
 105                        "never reach this point.");
 106     }
 107
 108     return Result;
 109   }
 110 };
 111
 112
 113 } // end namespace llvm
 114 #endif
 115
 116 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, "machine-block-freq",
 117                       "Machine Block Frequency Analysis", true, true)
 118 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
 119 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
 120 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, "machine-block-freq",
 121                     "Machine Block Frequency Analysis", true, true)
 122
 123 char MachineBlockFrequencyInfo::ID = 0;
 124
 125
 126 MachineBlockFrequencyInfo::
 127 MachineBlockFrequencyInfo() :MachineFunctionPass(ID) {
 128   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
 129 }
 130
 131 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {}
 132
 133 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
 134   AU.addRequired<MachineBranchProbabilityInfo>();
 135   AU.addRequired<MachineLoopInfo>();
 136   AU.setPreservesAll();
 137   MachineFunctionPass::getAnalysisUsage(AU);
 138 }
 139
 140 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
 141   MachineBranchProbabilityInfo &MBPI =
 142       getAnalysis<MachineBranchProbabilityInfo>();
 143   MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
 144   if (!MBFI)
 145     MBFI.reset(new ImplType);
 146   MBFI->doFunction(&F, &MBPI, &MLI);
 147 #ifndef NDEBUG
 148   if (ViewMachineBlockFreqPropagationDAG != GVDT_None) {
 149     view();
 150   }
 151 #endif
 152   return false;
 153 }
 154
 155 void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
 156
 157 /// Pop up a ghostview window with the current block frequency propagation
 158 /// rendered using dot.
 159 void MachineBlockFrequencyInfo::view() const {
 160 // This code is only for debugging.
 161 #ifndef NDEBUG
 162   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this),
 163             "MachineBlockFrequencyDAGs");
 164 #else
 165   errs() << "MachineBlockFrequencyInfo::view is only available in debug builds "
 166     "on systems with Graphviz or gv!\n";
 167 #endif // NDEBUG
 168 }
 169
 170 BlockFrequency MachineBlockFrequencyInfo::
 171 getBlockFreq(const MachineBasicBlock *MBB) const {
 172   return MBFI ? MBFI->getBlockFreq(MBB) : 0;
 173 }
 174
 175 const MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
 176   return MBFI ? MBFI->getFunction() : nullptr;
 177 }
 178
 179 raw_ostream &
 180 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
 181                                           const BlockFrequency Freq) const {
 182   return MBFI ? MBFI->printBlockFreq(OS, Freq) : OS;
 183 }
 184
 185 raw_ostream &
 186 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
 187                                           const MachineBasicBlock *MBB) const {
 188   return MBFI ? MBFI->printBlockFreq(OS, MBB) : OS;
 189 }
 190
 191 uint64_t MachineBlockFrequencyInfo::getEntryFreq() const {
 192   return MBFI ? MBFI->getEntryFreq() : 0;
 193 }