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/ADT/DenseMap.h"
  16 #include "llvm/ADT/None.h"
  17 #include "llvm/ADT/iterator.h"
  18 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
  19 #include "llvm/CodeGen/MachineBasicBlock.h"
  20 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
  21 #include "llvm/CodeGen/MachineFunction.h"
  22 #include "llvm/CodeGen/MachineLoopInfo.h"
  23 #include "llvm/Pass.h"
  24 #include "llvm/Support/CommandLine.h"
  25 #include "llvm/Support/GraphWriter.h"
  26 #include <string>
  27
  28 using namespace llvm;
  29
  30 #define DEBUG_TYPE "machine-block-freq"
  31
  32 static cl::opt<GVDAGType> ViewMachineBlockFreqPropagationDAG(
  33     "view-machine-block-freq-propagation-dags", cl::Hidden,
  34     cl::desc("Pop up a window to show a dag displaying how machine block "
  35              "frequencies propagate through the CFG."),
  36     cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
  37                clEnumValN(GVDT_Fraction, "fraction",
  38                           "display a graph using the "
  39                           "fractional block frequency representation."),
  40                clEnumValN(GVDT_Integer, "integer",
  41                           "display a graph using the raw "
  42                           "integer fractional block frequency representation."),
  43                clEnumValN(GVDT_Count, "count", "display a graph using the real "
  44                                                "profile count if available.")));
  45
  46 // Similar option above, but used to control BFI display only after MBP pass
  47 cl::opt<GVDAGType> ViewBlockLayoutWithBFI(
  48     "view-block-layout-with-bfi", cl::Hidden,
  49     cl::desc(
  50         "Pop up a window to show a dag displaying MBP layout and associated "
  51         "block frequencies of the CFG."),
  52     cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
  53                clEnumValN(GVDT_Fraction, "fraction",
  54                           "display a graph using the "
  55                           "fractional block frequency representation."),
  56                clEnumValN(GVDT_Integer, "integer",
  57                           "display a graph using the raw "
  58                           "integer fractional block frequency representation."),
  59                clEnumValN(GVDT_Count, "count",
  60                           "display a graph using the real "
  61                           "profile count if available.")));
  62
  63 // Command line option to specify the name of the function for CFG dump
  64 // Defined in Analysis/BlockFrequencyInfo.cpp:  -view-bfi-func-name=
  65 extern cl::opt<std::string> ViewBlockFreqFuncName;
  66
  67 // Command line option to specify hot frequency threshold.
  68 // Defined in Analysis/BlockFrequencyInfo.cpp:  -view-hot-freq-perc=
  69 extern cl::opt<unsigned> ViewHotFreqPercent;
  70
  71 static cl::opt<bool> PrintMachineBlockFreq(
  72     "print-machine-bfi", cl::init(false), cl::Hidden,
  73     cl::desc("Print the machine block frequency info."));
  74
  75 // Command line option to specify the name of the function for block frequency
  76 // dump. Defined in Analysis/BlockFrequencyInfo.cpp.
  77 extern cl::opt<std::string> PrintBlockFreqFuncName;
  78
  79 static GVDAGType getGVDT() {
  80   if (ViewBlockLayoutWithBFI != GVDT_None)
  81     return ViewBlockLayoutWithBFI;
  82
  83   return ViewMachineBlockFreqPropagationDAG;
  84 }
  85
  86 namespace llvm {
  87
  88 template <> struct GraphTraits<MachineBlockFrequencyInfo *> {
  89   using NodeRef = const MachineBasicBlock *;
  90   using ChildIteratorType = MachineBasicBlock::const_succ_iterator;
  91   using nodes_iterator = pointer_iterator<MachineFunction::const_iterator>;
  92
  93   static NodeRef getEntryNode(const MachineBlockFrequencyInfo *G) {
  94     return &G->getFunction()->front();
  95   }
  96
  97   static ChildIteratorType child_begin(const NodeRef N) {
  98     return N->succ_begin();
  99   }
 100
 101   static ChildIteratorType child_end(const NodeRef N) { return N->succ_end(); }
 102
 103   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
 104     return nodes_iterator(G->getFunction()->begin());
 105   }
 106
 107   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
 108     return nodes_iterator(G->getFunction()->end());
 109   }
 110 };
 111
 112 using MBFIDOTGraphTraitsBase =
 113     BFIDOTGraphTraitsBase<MachineBlockFrequencyInfo,
 114                           MachineBranchProbabilityInfo>;
 115
 116 template <>
 117 struct DOTGraphTraits<MachineBlockFrequencyInfo *>
 118     : public MBFIDOTGraphTraitsBase {
 119   const MachineFunction *CurFunc = nullptr;
 120   DenseMap<const MachineBasicBlock *, int> LayoutOrderMap;
 121
 122   explicit DOTGraphTraits(bool isSimple = false)
 123       : MBFIDOTGraphTraitsBase(isSimple) {}
 124
 125   std::string getNodeLabel(const MachineBasicBlock *Node,
 126                            const MachineBlockFrequencyInfo *Graph) {
 127     int layout_order = -1;
 128     // Attach additional ordering information if 'isSimple' is false.
 129     if (!isSimple()) {
 130       const MachineFunction *F = Node->getParent();
 131       if (!CurFunc || F != CurFunc) {
 132         if (CurFunc)
 133           LayoutOrderMap.clear();
 134
 135         CurFunc = F;
 136         int O = 0;
 137         for (auto MBI = F->begin(); MBI != F->end(); ++MBI, ++O) {
 138           LayoutOrderMap[&*MBI] = O;
 139         }
 140       }
 141       layout_order = LayoutOrderMap[Node];
 142     }
 143     return MBFIDOTGraphTraitsBase::getNodeLabel(Node, Graph, getGVDT(),
 144                                                 layout_order);
 145   }
 146
 147   std::string getNodeAttributes(const MachineBasicBlock *Node,
 148                                 const MachineBlockFrequencyInfo *Graph) {
 149     return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
 150                                                      ViewHotFreqPercent);
 151   }
 152
 153   std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
 154                                 const MachineBlockFrequencyInfo *MBFI) {
 155     return MBFIDOTGraphTraitsBase::getEdgeAttributes(
 156         Node, EI, MBFI, MBFI->getMBPI(), ViewHotFreqPercent);
 157   }
 158 };
 159
 160 } // end namespace llvm
 161
 162 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, DEBUG_TYPE,
 163                       "Machine Block Frequency Analysis", true, true)
 164 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
 165 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
 166 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, DEBUG_TYPE,
 167                     "Machine Block Frequency Analysis", true, true)
 168
 169 char MachineBlockFrequencyInfo::ID = 0;
 170
 171 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo()
 172     : MachineFunctionPass(ID) {
 173   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
 174 }
 175
 176 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() = default;
 177
 178 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
 179   AU.addRequired<MachineBranchProbabilityInfo>();
 180   AU.addRequired<MachineLoopInfo>();
 181   AU.setPreservesAll();
 182   MachineFunctionPass::getAnalysisUsage(AU);
 183 }
 184
 185 void MachineBlockFrequencyInfo::calculate(
 186     const MachineFunction &F, const MachineBranchProbabilityInfo &MBPI,
 187     const MachineLoopInfo &MLI) {
 188   if (!MBFI)
 189     MBFI.reset(new ImplType);
 190   MBFI->calculate(F, MBPI, MLI);
 191   if (ViewMachineBlockFreqPropagationDAG != GVDT_None &&
 192       (ViewBlockFreqFuncName.empty() ||
 193        F.getName().equals(ViewBlockFreqFuncName))) {
 194     view("MachineBlockFrequencyDAGS." + F.getName());
 195   }
 196   if (PrintMachineBlockFreq &&
 197       (PrintBlockFreqFuncName.empty() ||
 198        F.getName().equals(PrintBlockFreqFuncName))) {
 199     MBFI->print(dbgs());
 200   }
 201 }
 202
 203 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
 204   MachineBranchProbabilityInfo &MBPI =
 205       getAnalysis<MachineBranchProbabilityInfo>();
 206   MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
 207   calculate(F, MBPI, MLI);
 208   return false;
 209 }
 210
 211 void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
 212
 213 /// Pop up a ghostview window with the current block frequency propagation
 214 /// rendered using dot.
 215 void MachineBlockFrequencyInfo::view(const Twine &Name, bool isSimple) const {
 216   // This code is only for debugging.
 217   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this), Name, isSimple);
 218 }
 219
 220 BlockFrequency
 221 MachineBlockFrequencyInfo::getBlockFreq(const MachineBasicBlock *MBB) const {
 222   return MBFI ? MBFI->getBlockFreq(MBB) : 0;
 223 }
 224
 225 Optional<uint64_t> MachineBlockFrequencyInfo::getBlockProfileCount(
 226     const MachineBasicBlock *MBB) const {
 227   const Function &F = MBFI->getFunction()->getFunction();
 228   return MBFI ? MBFI->getBlockProfileCount(F, MBB) : None;
 229 }
 230
 231 Optional<uint64_t>
 232 MachineBlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const {
 233   const Function &F = MBFI->getFunction()->getFunction();
 234   return MBFI ? MBFI->getProfileCountFromFreq(F, Freq) : None;
 235 }
 236
 237 bool
 238 MachineBlockFrequencyInfo::isIrrLoopHeader(const MachineBasicBlock *MBB) {
 239   assert(MBFI && "Expected analysis to be available");
 240   return MBFI->isIrrLoopHeader(MBB);
 241 }
 242
 243 const MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
 244   return MBFI ? MBFI->getFunction() : nullptr;
 245 }
 246
 247 const MachineBranchProbabilityInfo *MachineBlockFrequencyInfo::getMBPI() const {
 248   return MBFI ? &MBFI->getBPI() : nullptr;
 249 }
 250
 251 raw_ostream &
 252 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
 253                                           const BlockFrequency Freq) const {
 254   return MBFI ? MBFI->printBlockFreq(OS, Freq) : OS;
 255 }
 256
 257 raw_ostream &
 258 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
 259                                           const MachineBasicBlock *MBB) const {
 260   return MBFI ? MBFI->printBlockFreq(OS, MBB) : OS;
 261 }
 262
 263 uint64_t MachineBlockFrequencyInfo::getEntryFreq() const {
 264   return MBFI ? MBFI->getEntryFreq() : 0;
 265 }