llvm/lib/Analysis/ProfileSummaryInfo.cpp

   1 //===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
   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 contains a pass that provides access to the global profile summary
  10 // information.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Analysis/ProfileSummaryInfo.h"
  15 #include "llvm/Analysis/BlockFrequencyInfo.h"
  16 #include "llvm/IR/BasicBlock.h"
  17 #include "llvm/IR/Instructions.h"
  18 #include "llvm/IR/Metadata.h"
  19 #include "llvm/IR/Module.h"
  20 #include "llvm/IR/ProfileSummary.h"
  21 #include "llvm/InitializePasses.h"
  22 #include "llvm/ProfileData/ProfileCommon.h"
  23 #include "llvm/Support/CommandLine.h"
  24 using namespace llvm;
  25
  26 // Knobs for profile summary based thresholds.
  27 extern cl::opt<int> ProfileSummaryCutoffHot;
  28 extern cl::opt<int> ProfileSummaryCutoffCold;
  29 extern cl::opt<unsigned> ProfileSummaryHugeWorkingSetSizeThreshold;
  30 extern cl::opt<unsigned> ProfileSummaryLargeWorkingSetSizeThreshold;
  31 extern cl::opt<int> ProfileSummaryHotCount;
  32 extern cl::opt<int> ProfileSummaryColdCount;
  33
  34 static cl::opt<bool> PartialProfile(
  35     "partial-profile", cl::Hidden, cl::init(false),
  36     cl::desc("Specify the current profile is used as a partial profile."));
  37
  38 cl::opt<bool> ScalePartialSampleProfileWorkingSetSize(
  39     "scale-partial-sample-profile-working-set-size", cl::Hidden, cl::init(true),
  40     cl::desc(
  41         "If true, scale the working set size of the partial sample profile "
  42         "by the partial profile ratio to reflect the size of the program "
  43         "being compiled."));
  44
  45 static cl::opt<double> PartialSampleProfileWorkingSetSizeScaleFactor(
  46     "partial-sample-profile-working-set-size-scale-factor", cl::Hidden,
  47     cl::init(0.008),
  48     cl::desc("The scale factor used to scale the working set size of the "
  49              "partial sample profile along with the partial profile ratio. "
  50              "This includes the factor of the profile counter per block "
  51              "and the factor to scale the working set size to use the same "
  52              "shared thresholds as PGO."));
  53
  54 // The profile summary metadata may be attached either by the frontend or by
  55 // any backend passes (IR level instrumentation, for example). This method
  56 // checks if the Summary is null and if so checks if the summary metadata is now
  57 // available in the module and parses it to get the Summary object.
  58 void ProfileSummaryInfo::refresh() {
  59   if (hasProfileSummary())
  60     return;
  61   // First try to get context sensitive ProfileSummary.
  62   auto *SummaryMD = M->getProfileSummary(/* IsCS */ true);
  63   if (SummaryMD)
  64     Summary.reset(ProfileSummary::getFromMD(SummaryMD));
  65
  66   if (!hasProfileSummary()) {
  67     // This will actually return PSK_Instr or PSK_Sample summary.
  68     SummaryMD = M->getProfileSummary(/* IsCS */ false);
  69     if (SummaryMD)
  70       Summary.reset(ProfileSummary::getFromMD(SummaryMD));
  71   }
  72   if (!hasProfileSummary())
  73     return;
  74   computeThresholds();
  75 }
  76
  77 Optional<uint64_t> ProfileSummaryInfo::getProfileCount(
  78     const CallBase &Call, BlockFrequencyInfo *BFI, bool AllowSynthetic) const {
  79   assert((isa<CallInst>(Call) || isa<InvokeInst>(Call)) &&
  80          "We can only get profile count for call/invoke instruction.");
  81   if (hasSampleProfile()) {
  82     // In sample PGO mode, check if there is a profile metadata on the
  83     // instruction. If it is present, determine hotness solely based on that,
  84     // since the sampled entry count may not be accurate. If there is no
  85     // annotated on the instruction, return None.
  86     uint64_t TotalCount;
  87     if (Call.extractProfTotalWeight(TotalCount))
  88       return TotalCount;
  89     return None;
  90   }
  91   if (BFI)
  92     return BFI->getBlockProfileCount(Call.getParent(), AllowSynthetic);
  93   return None;
  94 }
  95
  96 /// Returns true if the function's entry is hot. If it returns false, it
  97 /// either means it is not hot or it is unknown whether it is hot or not (for
  98 /// example, no profile data is available).
  99 bool ProfileSummaryInfo::isFunctionEntryHot(const Function *F) const {
 100   if (!F || !hasProfileSummary())
 101     return false;
 102   auto FunctionCount = F->getEntryCount();
 103   // FIXME: The heuristic used below for determining hotness is based on
 104   // preliminary SPEC tuning for inliner. This will eventually be a
 105   // convenience method that calls isHotCount.
 106   return FunctionCount && isHotCount(FunctionCount.getCount());
 107 }
 108
 109 /// Returns true if the function contains hot code. This can include a hot
 110 /// function entry count, hot basic block, or (in the case of Sample PGO)
 111 /// hot total call edge count.
 112 /// If it returns false, it either means it is not hot or it is unknown
 113 /// (for example, no profile data is available).
 114 bool ProfileSummaryInfo::isFunctionHotInCallGraph(
 115     const Function *F, BlockFrequencyInfo &BFI) const {
 116   if (!F || !hasProfileSummary())
 117     return false;
 118   if (auto FunctionCount = F->getEntryCount())
 119     if (isHotCount(FunctionCount.getCount()))
 120       return true;
 121
 122   if (hasSampleProfile()) {
 123     uint64_t TotalCallCount = 0;
 124     for (const auto &BB : *F)
 125       for (const auto &I : BB)
 126         if (isa<CallInst>(I) || isa<InvokeInst>(I))
 127           if (auto CallCount = getProfileCount(cast<CallBase>(I), nullptr))
 128             TotalCallCount += CallCount.getValue();
 129     if (isHotCount(TotalCallCount))
 130       return true;
 131   }
 132   for (const auto &BB : *F)
 133     if (isHotBlock(&BB, &BFI))
 134       return true;
 135   return false;
 136 }
 137
 138 /// Returns true if the function only contains cold code. This means that
 139 /// the function entry and blocks are all cold, and (in the case of Sample PGO)
 140 /// the total call edge count is cold.
 141 /// If it returns false, it either means it is not cold or it is unknown
 142 /// (for example, no profile data is available).
 143 bool ProfileSummaryInfo::isFunctionColdInCallGraph(
 144     const Function *F, BlockFrequencyInfo &BFI) const {
 145   if (!F || !hasProfileSummary())
 146     return false;
 147   if (auto FunctionCount = F->getEntryCount())
 148     if (!isColdCount(FunctionCount.getCount()))
 149       return false;
 150
 151   if (hasSampleProfile()) {
 152     uint64_t TotalCallCount = 0;
 153     for (const auto &BB : *F)
 154       for (const auto &I : BB)
 155         if (isa<CallInst>(I) || isa<InvokeInst>(I))
 156           if (auto CallCount = getProfileCount(cast<CallBase>(I), nullptr))
 157             TotalCallCount += CallCount.getValue();
 158     if (!isColdCount(TotalCallCount))
 159       return false;
 160   }
 161   for (const auto &BB : *F)
 162     if (!isColdBlock(&BB, &BFI))
 163       return false;
 164   return true;
 165 }
 166
 167 bool ProfileSummaryInfo::isFunctionHotnessUnknown(const Function &F) const {
 168   assert(hasPartialSampleProfile() && "Expect partial sample profile");
 169   return !F.getEntryCount().hasValue();
 170 }
 171
 172 template <bool isHot>
 173 bool ProfileSummaryInfo::isFunctionHotOrColdInCallGraphNthPercentile(
 174     int PercentileCutoff, const Function *F, BlockFrequencyInfo &BFI) const {
 175   if (!F || !hasProfileSummary())
 176     return false;
 177   if (auto FunctionCount = F->getEntryCount()) {
 178     if (isHot &&
 179         isHotCountNthPercentile(PercentileCutoff, FunctionCount.getCount()))
 180       return true;
 181     if (!isHot &&
 182         !isColdCountNthPercentile(PercentileCutoff, FunctionCount.getCount()))
 183       return false;
 184   }
 185   if (hasSampleProfile()) {
 186     uint64_t TotalCallCount = 0;
 187     for (const auto &BB : *F)
 188       for (const auto &I : BB)
 189         if (isa<CallInst>(I) || isa<InvokeInst>(I))
 190           if (auto CallCount = getProfileCount(cast<CallBase>(I), nullptr))
 191             TotalCallCount += CallCount.getValue();
 192     if (isHot && isHotCountNthPercentile(PercentileCutoff, TotalCallCount))
 193       return true;
 194     if (!isHot && !isColdCountNthPercentile(PercentileCutoff, TotalCallCount))
 195       return false;
 196   }
 197   for (const auto &BB : *F) {
 198     if (isHot && isHotBlockNthPercentile(PercentileCutoff, &BB, &BFI))
 199       return true;
 200     if (!isHot && !isColdBlockNthPercentile(PercentileCutoff, &BB, &BFI))
 201       return false;
 202   }
 203   return !isHot;
 204 }
 205
 206 // Like isFunctionHotInCallGraph but for a given cutoff.
 207 bool ProfileSummaryInfo::isFunctionHotInCallGraphNthPercentile(
 208     int PercentileCutoff, const Function *F, BlockFrequencyInfo &BFI) const {
 209   return isFunctionHotOrColdInCallGraphNthPercentile<true>(
 210       PercentileCutoff, F, BFI);
 211 }
 212
 213 bool ProfileSummaryInfo::isFunctionColdInCallGraphNthPercentile(
 214     int PercentileCutoff, const Function *F, BlockFrequencyInfo &BFI) const {
 215   return isFunctionHotOrColdInCallGraphNthPercentile<false>(
 216       PercentileCutoff, F, BFI);
 217 }
 218
 219 /// Returns true if the function's entry is a cold. If it returns false, it
 220 /// either means it is not cold or it is unknown whether it is cold or not (for
 221 /// example, no profile data is available).
 222 bool ProfileSummaryInfo::isFunctionEntryCold(const Function *F) const {
 223   if (!F)
 224     return false;
 225   if (F->hasFnAttribute(Attribute::Cold))
 226     return true;
 227   if (!hasProfileSummary())
 228     return false;
 229   auto FunctionCount = F->getEntryCount();
 230   // FIXME: The heuristic used below for determining coldness is based on
 231   // preliminary SPEC tuning for inliner. This will eventually be a
 232   // convenience method that calls isHotCount.
 233   return FunctionCount && isColdCount(FunctionCount.getCount());
 234 }
 235
 236 /// Compute the hot and cold thresholds.
 237 void ProfileSummaryInfo::computeThresholds() {
 238   auto &DetailedSummary = Summary->getDetailedSummary();
 239   auto &HotEntry = ProfileSummaryBuilder::getEntryForPercentile(
 240       DetailedSummary, ProfileSummaryCutoffHot);
 241   HotCountThreshold =
 242       ProfileSummaryBuilder::getHotCountThreshold(DetailedSummary);
 243   ColdCountThreshold =
 244       ProfileSummaryBuilder::getColdCountThreshold(DetailedSummary);
 245   assert(ColdCountThreshold <= HotCountThreshold &&
 246          "Cold count threshold cannot exceed hot count threshold!");
 247   if (!hasPartialSampleProfile() || !ScalePartialSampleProfileWorkingSetSize) {
 248     HasHugeWorkingSetSize =
 249         HotEntry.NumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
 250     HasLargeWorkingSetSize =
 251         HotEntry.NumCounts > ProfileSummaryLargeWorkingSetSizeThreshold;
 252   } else {
 253     // Scale the working set size of the partial sample profile to reflect the
 254     // size of the program being compiled.
 255     double PartialProfileRatio = Summary->getPartialProfileRatio();
 256     uint64_t ScaledHotEntryNumCounts =
 257         static_cast<uint64_t>(HotEntry.NumCounts * PartialProfileRatio *
 258                               PartialSampleProfileWorkingSetSizeScaleFactor);
 259     HasHugeWorkingSetSize =
 260         ScaledHotEntryNumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
 261     HasLargeWorkingSetSize =
 262         ScaledHotEntryNumCounts > ProfileSummaryLargeWorkingSetSizeThreshold;
 263   }
 264 }
 265
 266 Optional<uint64_t>
 267 ProfileSummaryInfo::computeThreshold(int PercentileCutoff) const {
 268   if (!hasProfileSummary())
 269     return None;
 270   auto iter = ThresholdCache.find(PercentileCutoff);
 271   if (iter != ThresholdCache.end()) {
 272     return iter->second;
 273   }
 274   auto &DetailedSummary = Summary->getDetailedSummary();
 275   auto &Entry = ProfileSummaryBuilder::getEntryForPercentile(DetailedSummary,
 276                                                              PercentileCutoff);
 277   uint64_t CountThreshold = Entry.MinCount;
 278   ThresholdCache[PercentileCutoff] = CountThreshold;
 279   return CountThreshold;
 280 }
 281
 282 bool ProfileSummaryInfo::hasHugeWorkingSetSize() const {
 283   return HasHugeWorkingSetSize && HasHugeWorkingSetSize.getValue();
 284 }
 285
 286 bool ProfileSummaryInfo::hasLargeWorkingSetSize() const {
 287   return HasLargeWorkingSetSize && HasLargeWorkingSetSize.getValue();
 288 }
 289
 290 bool ProfileSummaryInfo::isHotCount(uint64_t C) const {
 291   return HotCountThreshold && C >= HotCountThreshold.getValue();
 292 }
 293
 294 bool ProfileSummaryInfo::isColdCount(uint64_t C) const {
 295   return ColdCountThreshold && C <= ColdCountThreshold.getValue();
 296 }
 297
 298 template <bool isHot>
 299 bool ProfileSummaryInfo::isHotOrColdCountNthPercentile(int PercentileCutoff,
 300                                                        uint64_t C) const {
 301   auto CountThreshold = computeThreshold(PercentileCutoff);
 302   if (isHot)
 303     return CountThreshold && C >= CountThreshold.getValue();
 304   else
 305     return CountThreshold && C <= CountThreshold.getValue();
 306 }
 307
 308 bool ProfileSummaryInfo::isHotCountNthPercentile(int PercentileCutoff,
 309                                                  uint64_t C) const {
 310   return isHotOrColdCountNthPercentile<true>(PercentileCutoff, C);
 311 }
 312
 313 bool ProfileSummaryInfo::isColdCountNthPercentile(int PercentileCutoff,
 314                                                   uint64_t C) const {
 315   return isHotOrColdCountNthPercentile<false>(PercentileCutoff, C);
 316 }
 317
 318 uint64_t ProfileSummaryInfo::getOrCompHotCountThreshold() const {
 319   return HotCountThreshold ? HotCountThreshold.getValue() : UINT64_MAX;
 320 }
 321
 322 uint64_t ProfileSummaryInfo::getOrCompColdCountThreshold() const {
 323   return ColdCountThreshold ? ColdCountThreshold.getValue() : 0;
 324 }
 325
 326 bool ProfileSummaryInfo::isHotBlock(const BasicBlock *BB,
 327                                     BlockFrequencyInfo *BFI) const {
 328   auto Count = BFI->getBlockProfileCount(BB);
 329   return Count && isHotCount(*Count);
 330 }
 331
 332 bool ProfileSummaryInfo::isColdBlock(const BasicBlock *BB,
 333                                      BlockFrequencyInfo *BFI) const {
 334   auto Count = BFI->getBlockProfileCount(BB);
 335   return Count && isColdCount(*Count);
 336 }
 337
 338 template <bool isHot>
 339 bool ProfileSummaryInfo::isHotOrColdBlockNthPercentile(
 340     int PercentileCutoff, const BasicBlock *BB, BlockFrequencyInfo *BFI) const {
 341   auto Count = BFI->getBlockProfileCount(BB);
 342   if (isHot)
 343     return Count && isHotCountNthPercentile(PercentileCutoff, *Count);
 344   else
 345     return Count && isColdCountNthPercentile(PercentileCutoff, *Count);
 346 }
 347
 348 bool ProfileSummaryInfo::isHotBlockNthPercentile(
 349     int PercentileCutoff, const BasicBlock *BB, BlockFrequencyInfo *BFI) const {
 350   return isHotOrColdBlockNthPercentile<true>(PercentileCutoff, BB, BFI);
 351 }
 352
 353 bool ProfileSummaryInfo::isColdBlockNthPercentile(
 354     int PercentileCutoff, const BasicBlock *BB, BlockFrequencyInfo *BFI) const {
 355   return isHotOrColdBlockNthPercentile<false>(PercentileCutoff, BB, BFI);
 356 }
 357
 358 bool ProfileSummaryInfo::isHotCallSite(const CallBase &CB,
 359                                        BlockFrequencyInfo *BFI) const {
 360   auto C = getProfileCount(CB, BFI);
 361   return C && isHotCount(*C);
 362 }
 363
 364 bool ProfileSummaryInfo::isColdCallSite(const CallBase &CB,
 365                                         BlockFrequencyInfo *BFI) const {
 366   auto C = getProfileCount(CB, BFI);
 367   if (C)
 368     return isColdCount(*C);
 369
 370   // In SamplePGO, if the caller has been sampled, and there is no profile
 371   // annotated on the callsite, we consider the callsite as cold.
 372   return hasSampleProfile() && CB.getCaller()->hasProfileData();
 373 }
 374
 375 bool ProfileSummaryInfo::hasPartialSampleProfile() const {
 376   return hasProfileSummary() &&
 377          Summary->getKind() == ProfileSummary::PSK_Sample &&
 378          (PartialProfile || Summary->isPartialProfile());
 379 }
 380
 381 INITIALIZE_PASS(ProfileSummaryInfoWrapperPass, "profile-summary-info",
 382                 "Profile summary info", false, true)
 383
 384 ProfileSummaryInfoWrapperPass::ProfileSummaryInfoWrapperPass()
 385     : ImmutablePass(ID) {
 386   initializeProfileSummaryInfoWrapperPassPass(*PassRegistry::getPassRegistry());
 387 }
 388
 389 bool ProfileSummaryInfoWrapperPass::doInitialization(Module &M) {
 390   PSI.reset(new ProfileSummaryInfo(M));
 391   return false;
 392 }
 393
 394 bool ProfileSummaryInfoWrapperPass::doFinalization(Module &M) {
 395   PSI.reset();
 396   return false;
 397 }
 398
 399 AnalysisKey ProfileSummaryAnalysis::Key;
 400 ProfileSummaryInfo ProfileSummaryAnalysis::run(Module &M,
 401                                                ModuleAnalysisManager &) {
 402   return ProfileSummaryInfo(M);
 403 }
 404
 405 PreservedAnalyses ProfileSummaryPrinterPass::run(Module &M,
 406                                                  ModuleAnalysisManager &AM) {
 407   ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
 408
 409   OS << "Functions in " << M.getName() << " with hot/cold annotations: \n";
 410   for (auto &F : M) {
 411     OS << F.getName();
 412     if (PSI.isFunctionEntryHot(&F))
 413       OS << " :hot entry ";
 414     else if (PSI.isFunctionEntryCold(&F))
 415       OS << " :cold entry ";
 416     OS << "\n";
 417   }
 418   return PreservedAnalyses::all();
 419 }
 420
 421 char ProfileSummaryInfoWrapperPass::ID = 0;