lib/CodeGen/MachineBlockFrequencyInfo.cpp

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