bolt/lib/Core/DynoStats.cpp

   1 //===- bolt/Core/DynoStats.cpp - Dynamic execution stats ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the DynoStats class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "bolt/Core/DynoStats.h"
  14 #include "bolt/Core/BinaryBasicBlock.h"
  15 #include "bolt/Core/BinaryFunction.h"
  16 #include "llvm/ADT/StringRef.h"
  17 #include "llvm/Support/CommandLine.h"
  18 #include "llvm/Support/Debug.h"
  19 #include "llvm/Support/raw_ostream.h"
  20 #include <algorithm>
  21 #include <string>
  22
  23 #undef  DEBUG_TYPE
  24 #define DEBUG_TYPE "bolt"
  25
  26 using namespace llvm;
  27 using namespace bolt;
  28
  29 namespace opts {
  30
  31 extern cl::OptionCategory BoltCategory;
  32
  33 static cl::opt<uint32_t>
  34 DynoStatsScale("dyno-stats-scale",
  35   cl::desc("scale to be applied while reporting dyno stats"),
  36   cl::Optional,
  37   cl::init(1),
  38   cl::Hidden,
  39   cl::cat(BoltCategory));
  40
  41 static cl::opt<uint32_t>
  42 PrintDynoOpcodeStat("print-dyno-opcode-stats",
  43   cl::desc("print per instruction opcode dyno stats and the function"
  44               "names:BB offsets of the nth highest execution counts"),
  45   cl::init(0),
  46   cl::Hidden,
  47   cl::cat(BoltCategory));
  48
  49 } // namespace opts
  50
  51 namespace llvm {
  52 namespace bolt {
  53
  54 constexpr const char *DynoStats::Desc[];
  55
  56 bool DynoStats::operator<(const DynoStats &Other) const {
  57   return std::lexicographical_compare(
  58       &Stats[FIRST_DYNO_STAT], &Stats[LAST_DYNO_STAT],
  59       &Other.Stats[FIRST_DYNO_STAT], &Other.Stats[LAST_DYNO_STAT]);
  60 }
  61
  62 bool DynoStats::operator==(const DynoStats &Other) const {
  63   return std::equal(&Stats[FIRST_DYNO_STAT], &Stats[LAST_DYNO_STAT],
  64                     &Other.Stats[FIRST_DYNO_STAT]);
  65 }
  66
  67 bool DynoStats::lessThan(const DynoStats &Other,
  68                          ArrayRef<Category> Keys) const {
  69   return std::lexicographical_compare(
  70       Keys.begin(), Keys.end(), Keys.begin(), Keys.end(),
  71       [this, &Other](const Category A, const Category) {
  72         return Stats[A] < Other.Stats[A];
  73       });
  74 }
  75
  76 void DynoStats::print(raw_ostream &OS, const DynoStats *Other,
  77                       MCInstPrinter *Printer) const {
  78   auto printStatWithDelta = [&](const std::string &Name, uint64_t Stat,
  79                                 uint64_t OtherStat) {
  80     OS << format("%'20lld : ", Stat * opts::DynoStatsScale) << Name;
  81     if (Other) {
  82       if (Stat != OtherStat) {
  83         OtherStat = std::max(OtherStat, uint64_t(1)); // to prevent divide by 0
  84         OS << format(" (%+.1f%%)", ((float)Stat - (float)OtherStat) * 100.0 /
  85                                        (float)(OtherStat));
  86       } else {
  87         OS << " (=)";
  88       }
  89     }
  90     OS << '\n';
  91   };
  92
  93   for (auto Stat = DynoStats::FIRST_DYNO_STAT + 1;
  94        Stat < DynoStats::LAST_DYNO_STAT; ++Stat) {
  95
  96     if (!PrintAArch64Stats && Stat == DynoStats::VENEER_CALLS_AARCH64)
  97       continue;
  98
  99     printStatWithDelta(Desc[Stat], Stats[Stat], Other ? (*Other)[Stat] : 0);
 100   }
 101   if (opts::PrintDynoOpcodeStat && Printer) {
 102     outs() << "\nProgram-wide opcode histogram:\n";
 103     OS << "              Opcode,   Execution Count,     Max Exec Count, "
 104           "Function Name:Offset ...\n";
 105     std::vector<std::pair<uint64_t, unsigned>> SortedHistogram;
 106     for (const OpcodeStatTy &Stat : OpcodeHistogram)
 107       SortedHistogram.emplace_back(Stat.second.first, Stat.first);
 108
 109     // Sort using lexicographic ordering
 110     llvm::sort(SortedHistogram);
 111
 112     // Dump in ascending order: Start with Opcode with Highest execution
 113     // count.
 114     for (auto &Stat : llvm::reverse(SortedHistogram)) {
 115       OS << format("%20s,%'18lld", Printer->getOpcodeName(Stat.second).data(),
 116                    Stat.first * opts::DynoStatsScale);
 117
 118       MaxOpcodeHistogramTy MaxMultiMap = OpcodeHistogram.at(Stat.second).second;
 119       // Start with function name:BB offset with highest execution count.
 120       for (auto &Max : llvm::reverse(MaxMultiMap)) {
 121         OS << format(", %'18lld, ", Max.first * opts::DynoStatsScale)
 122            << Max.second.first.str() << ':' << Max.second.second;
 123       }
 124       OS << '\n';
 125     }
 126   }
 127 }
 128
 129 void DynoStats::operator+=(const DynoStats &Other) {
 130   for (auto Stat = DynoStats::FIRST_DYNO_STAT + 1;
 131        Stat < DynoStats::LAST_DYNO_STAT; ++Stat) {
 132     Stats[Stat] += Other[Stat];
 133   }
 134   for (const OpcodeStatTy &Stat : Other.OpcodeHistogram) {
 135     auto I = OpcodeHistogram.find(Stat.first);
 136     if (I == OpcodeHistogram.end()) {
 137       OpcodeHistogram.emplace(Stat);
 138     } else {
 139       // Merge Other Historgrams, log only the opts::PrintDynoOpcodeStat'th
 140       // maximum counts.
 141       I->second.first += Stat.second.first;
 142       auto &MMap = I->second.second;
 143       auto &OtherMMap = Stat.second.second;
 144       auto Size = MMap.size();
 145       assert(Size <= opts::PrintDynoOpcodeStat);
 146       for (auto OtherMMapPair : llvm::reverse(OtherMMap)) {
 147         if (Size++ >= opts::PrintDynoOpcodeStat) {
 148           auto First = MMap.begin();
 149           if (OtherMMapPair.first <= First->first)
 150             break;
 151           MMap.erase(First);
 152         }
 153         MMap.emplace(OtherMMapPair);
 154       }
 155     }
 156   }
 157 }
 158
 159 DynoStats getDynoStats(BinaryFunction &BF) {
 160   auto &BC = BF.getBinaryContext();
 161
 162   DynoStats Stats(/*PrintAArch64Stats*/ BC.isAArch64());
 163
 164   // Return empty-stats about the function we don't completely understand.
 165   if (!BF.isSimple() || !BF.hasValidProfile() || !BF.hasCanonicalCFG())
 166     return Stats;
 167
 168   // Update enumeration of basic blocks for correct detection of branch'
 169   // direction.
 170   BF.getLayout().updateLayoutIndices();
 171
 172   for (BinaryBasicBlock *const BB : BF.getLayout().blocks()) {
 173     // The basic block execution count equals to the sum of incoming branch
 174     // frequencies. This may deviate from the sum of outgoing branches of the
 175     // basic block especially since the block may contain a function that
 176     // does not return or a function that throws an exception.
 177     const uint64_t BBExecutionCount = BB->getKnownExecutionCount();
 178
 179     // Ignore empty blocks and blocks that were not executed.
 180     if (BB->getNumNonPseudos() == 0 || BBExecutionCount == 0)
 181       continue;
 182
 183     // Count AArch64 linker-inserted veneers
 184     if (BF.isAArch64Veneer())
 185       Stats[DynoStats::VENEER_CALLS_AARCH64] += BF.getKnownExecutionCount();
 186
 187     // Count various instruction types by iterating through all instructions.
 188     // When -print-dyno-opcode-stats is on, count per each opcode and record
 189     // maximum execution counts.
 190     for (const MCInst &Instr : *BB) {
 191       if (opts::PrintDynoOpcodeStat) {
 192         unsigned Opcode = Instr.getOpcode();
 193         auto I = Stats.OpcodeHistogram.find(Opcode);
 194         if (I == Stats.OpcodeHistogram.end()) {
 195           DynoStats::MaxOpcodeHistogramTy MMap;
 196           MMap.emplace(BBExecutionCount,
 197                        std::make_pair(BF.getOneName(), BB->getOffset()));
 198           Stats.OpcodeHistogram.emplace(Opcode,
 199                                         std::make_pair(BBExecutionCount, MMap));
 200         } else {
 201           I->second.first += BBExecutionCount;
 202           bool Insert = true;
 203           if (I->second.second.size() == opts::PrintDynoOpcodeStat) {
 204             auto First = I->second.second.begin();
 205             if (First->first < BBExecutionCount)
 206               I->second.second.erase(First);
 207             else
 208               Insert = false;
 209           }
 210           if (Insert) {
 211             I->second.second.emplace(
 212                 BBExecutionCount,
 213                 std::make_pair(BF.getOneName(), BB->getOffset()));
 214           }
 215         }
 216       }
 217
 218       if (BC.MIB->mayStore(Instr)) {
 219         Stats[DynoStats::STORES] += BBExecutionCount;
 220       }
 221       if (BC.MIB->mayLoad(Instr)) {
 222         Stats[DynoStats::LOADS] += BBExecutionCount;
 223       }
 224       if (!BC.MIB->isCall(Instr))
 225         continue;
 226
 227       uint64_t CallFreq = BBExecutionCount;
 228       if (BC.MIB->getConditionalTailCall(Instr)) {
 229         CallFreq =
 230             BC.MIB->getAnnotationWithDefault<uint64_t>(Instr, "CTCTakenCount");
 231       }
 232       Stats[DynoStats::FUNCTION_CALLS] += CallFreq;
 233       if (BC.MIB->isIndirectCall(Instr)) {
 234         Stats[DynoStats::INDIRECT_CALLS] += CallFreq;
 235       } else if (const MCSymbol *CallSymbol = BC.MIB->getTargetSymbol(Instr)) {
 236         const BinaryFunction *BF = BC.getFunctionForSymbol(CallSymbol);
 237         if (BF && BF->isPLTFunction()) {
 238           Stats[DynoStats::PLT_CALLS] += CallFreq;
 239
 240           // We don't process PLT functions and hence have to adjust relevant
 241           // dynostats here for:
 242           //
 243           //   jmp *GOT_ENTRY(%rip)
 244           //
 245           // NOTE: this is arch-specific.
 246           Stats[DynoStats::FUNCTION_CALLS] += CallFreq;
 247           Stats[DynoStats::INDIRECT_CALLS] += CallFreq;
 248           Stats[DynoStats::LOADS] += CallFreq;
 249           Stats[DynoStats::INSTRUCTIONS] += CallFreq;
 250         }
 251       }
 252     }
 253
 254     Stats[DynoStats::INSTRUCTIONS] += BB->getNumNonPseudos() * BBExecutionCount;
 255
 256     // Jump tables.
 257     const MCInst *LastInstr = BB->getLastNonPseudoInstr();
 258     if (BC.MIB->getJumpTable(*LastInstr)) {
 259       Stats[DynoStats::JUMP_TABLE_BRANCHES] += BBExecutionCount;
 260       LLVM_DEBUG(
 261         static uint64_t MostFrequentJT;
 262         if (BBExecutionCount > MostFrequentJT) {
 263           MostFrequentJT = BBExecutionCount;
 264           dbgs() << "BOLT-INFO: most frequently executed jump table is in "
 265                  << "function " << BF << " in basic block " << BB->getName()
 266                  << " executed totally " << BBExecutionCount << " times.\n";
 267         }
 268       );
 269       continue;
 270     }
 271
 272     if (BC.MIB->isIndirectBranch(*LastInstr) && !BC.MIB->isCall(*LastInstr)) {
 273       Stats[DynoStats::UNKNOWN_INDIRECT_BRANCHES] += BBExecutionCount;
 274       continue;
 275     }
 276
 277     // Update stats for branches.
 278     const MCSymbol *TBB = nullptr;
 279     const MCSymbol *FBB = nullptr;
 280     MCInst *CondBranch = nullptr;
 281     MCInst *UncondBranch = nullptr;
 282     if (!BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch))
 283       continue;
 284
 285     if (!CondBranch && !UncondBranch)
 286       continue;
 287
 288     // Simple unconditional branch.
 289     if (!CondBranch) {
 290       Stats[DynoStats::UNCOND_BRANCHES] += BBExecutionCount;
 291       continue;
 292     }
 293
 294     // CTCs: instruction annotations could be stripped, hence check the number
 295     // of successors to identify conditional tail calls.
 296     if (BB->succ_size() == 1) {
 297       if (BB->branch_info_begin() != BB->branch_info_end())
 298         Stats[DynoStats::UNCOND_BRANCHES] += BB->branch_info_begin()->Count;
 299       continue;
 300     }
 301
 302     // Conditional branch that could be followed by an unconditional branch.
 303     uint64_t TakenCount = BB->getTakenBranchInfo().Count;
 304     if (TakenCount == BinaryBasicBlock::COUNT_NO_PROFILE)
 305       TakenCount = 0;
 306
 307     uint64_t NonTakenCount = BB->getFallthroughBranchInfo().Count;
 308     if (NonTakenCount == BinaryBasicBlock::COUNT_NO_PROFILE)
 309       NonTakenCount = 0;
 310
 311     if (BF.isForwardBranch(BB, BB->getConditionalSuccessor(true))) {
 312       Stats[DynoStats::FORWARD_COND_BRANCHES] += BBExecutionCount;
 313       Stats[DynoStats::FORWARD_COND_BRANCHES_TAKEN] += TakenCount;
 314     } else {
 315       Stats[DynoStats::BACKWARD_COND_BRANCHES] += BBExecutionCount;
 316       Stats[DynoStats::BACKWARD_COND_BRANCHES_TAKEN] += TakenCount;
 317     }
 318
 319     if (UncondBranch) {
 320       Stats[DynoStats::UNCOND_BRANCHES] += NonTakenCount;
 321     }
 322   }
 323
 324   return Stats;
 325 }
 326
 327 } // namespace bolt
 328 } // namespace llvm