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/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 propagate 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
  55   const NodeType *getEntryNode(const MachineBlockFrequencyInfo *G) {
  56     return G->getFunction()->begin();
  57   }
  58
  59   static ChildIteratorType child_begin(const NodeType *N) {
  60     return N->succ_begin();
  61   }
  62
  63   static ChildIteratorType child_end(const NodeType *N) {
  64     return N->succ_end();
  65   }
  66
  67   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
  68     return G->getFunction()->begin();
  69   }
  70
  71   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
  72     return G->getFunction()->end();
  73   }
  74 };
  75
  76 template<>
  77 struct DOTGraphTraits<MachineBlockFrequencyInfo*> :
  78     public DefaultDOTGraphTraits {
  79   explicit DOTGraphTraits(bool isSimple=false) :
  80     DefaultDOTGraphTraits(isSimple) {}
  81
  82   static std::string getGraphName(const MachineBlockFrequencyInfo *G) {
  83     return G->getFunction()->getName();
  84   }
  85
  86   std::string getNodeLabel(const MachineBasicBlock *Node,
  87                            const MachineBlockFrequencyInfo *Graph) {
  88     std::string Result;
  89     raw_string_ostream OS(Result);
  90
  91     OS << Node->getName().str() << ":";
  92     switch (ViewMachineBlockFreqPropagationDAG) {
  93     case GVDT_Fraction:
  94       Graph->getBlockFreq(Node).print(OS);
  95       break;
  96     case GVDT_Integer:
  97       OS << Graph->getBlockFreq(Node).getFrequency();
  98       break;
  99     case GVDT_None:
 100       llvm_unreachable("If we are not supposed to render a graph we should "
 101                        "never reach this point.");
 102     }
 103
 104     return Result;
 105   }
 106 };
 107
 108
 109 } // end namespace llvm
 110 #endif
 111
 112 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, "machine-block-freq",
 113                       "Machine Block Frequency Analysis", true, true)
 114 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
 115 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, "machine-block-freq",
 116                     "Machine Block Frequency Analysis", true, true)
 117
 118 char MachineBlockFrequencyInfo::ID = 0;
 119
 120
 121 MachineBlockFrequencyInfo::
 122 MachineBlockFrequencyInfo() :MachineFunctionPass(ID) {
 123   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
 124   MBFI = new BlockFrequencyImpl<MachineBasicBlock, MachineFunction,
 125                                 MachineBranchProbabilityInfo>();
 126 }
 127
 128 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {
 129   delete MBFI;
 130 }
 131
 132 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
 133   AU.addRequired<MachineBranchProbabilityInfo>();
 134   AU.setPreservesAll();
 135   MachineFunctionPass::getAnalysisUsage(AU);
 136 }
 137
 138 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
 139   MachineBranchProbabilityInfo &MBPI =
 140     getAnalysis<MachineBranchProbabilityInfo>();
 141   MBFI->doFunction(&F, &MBPI);
 142 #ifndef NDEBUG
 143   if (ViewMachineBlockFreqPropagationDAG != GVDT_None) {
 144     view();
 145   }
 146 #endif
 147   return false;
 148 }
 149
 150 /// Pop up a ghostview window with the current block frequency propagation
 151 /// rendered using dot.
 152 void MachineBlockFrequencyInfo::view() const {
 153 // This code is only for debugging.
 154 #ifndef NDEBUG
 155   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this),
 156             "MachineBlockFrequencyDAGs");
 157 #else
 158   errs() << "MachineBlockFrequencyInfo::view is only available in debug builds "
 159     "on systems with Graphviz or gv!\n";
 160 #endif // NDEBUG
 161 }
 162
 163 BlockFrequency MachineBlockFrequencyInfo::
 164 getBlockFreq(const MachineBasicBlock *MBB) const {
 165   return MBFI->getBlockFreq(MBB);
 166 }
 167
 168 MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
 169   return MBFI->Fn;
 170 }