LCOV - code coverage report
Current view: top level - lib/Analysis - ProfileSummaryInfo.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 127 129 98.4 %
Date: 2017-09-14 15:23:50 Functions: 24 24 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
       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             : // This file contains a pass that provides access to the global profile summary
      11             : // information.
      12             : //
      13             : //===----------------------------------------------------------------------===//
      14             : 
      15             : #include "llvm/Analysis/ProfileSummaryInfo.h"
      16             : #include "llvm/Analysis/BlockFrequencyInfo.h"
      17             : #include "llvm/IR/BasicBlock.h"
      18             : #include "llvm/IR/CallSite.h"
      19             : #include "llvm/IR/Metadata.h"
      20             : #include "llvm/IR/Module.h"
      21             : #include "llvm/IR/ProfileSummary.h"
      22             : using namespace llvm;
      23             : 
      24             : // The following two parameters determine the threshold for a count to be
      25             : // considered hot/cold. These two parameters are percentile values (multiplied
      26             : // by 10000). If the counts are sorted in descending order, the minimum count to
      27             : // reach ProfileSummaryCutoffHot gives the threshold to determine a hot count.
      28             : // Similarly, the minimum count to reach ProfileSummaryCutoffCold gives the
      29             : // threshold for determining cold count (everything <= this threshold is
      30             : // considered cold).
      31             : 
      32       72306 : static cl::opt<int> ProfileSummaryCutoffHot(
      33      216918 :     "profile-summary-cutoff-hot", cl::Hidden, cl::init(990000), cl::ZeroOrMore,
      34      216918 :     cl::desc("A count is hot if it exceeds the minimum count to"
      35      216918 :              " reach this percentile of total counts."));
      36             : 
      37       72306 : static cl::opt<int> ProfileSummaryCutoffCold(
      38      216918 :     "profile-summary-cutoff-cold", cl::Hidden, cl::init(999999), cl::ZeroOrMore,
      39      216918 :     cl::desc("A count is cold if it is below the minimum count"
      40      216918 :              " to reach this percentile of total counts."));
      41             : 
      42       72306 : static cl::opt<bool> ProfileSampleAccurate(
      43      216918 :     "profile-sample-accurate", cl::Hidden, cl::init(false),
      44      216918 :     cl::desc("If the sample profile is accurate, we will mark all un-sampled "
      45             :              "callsite as cold. Otherwise, treat un-sampled callsites as if "
      46       72306 :              "we have no profile."));
      47       72306 : static cl::opt<unsigned> ProfileSummaryHugeWorkingSetSizeThreshold(
      48             :     "profile-summary-huge-working-set-size-threshold", cl::Hidden,
      49      216918 :     cl::init(15000), cl::ZeroOrMore,
      50      216918 :     cl::desc("The code working set size is considered huge if the number of"
      51             :              " blocks required to reach the -profile-summary-cutoff-hot"
      52      216918 :              " percentile exceeds this count."));
      53             : 
      54             : // Find the summary entry for a desired percentile of counts.
      55          80 : static const ProfileSummaryEntry &getEntryForPercentile(SummaryEntryVector &DS,
      56             :                                                         uint64_t Percentile) {
      57             :   auto Compare = [](const ProfileSummaryEntry &Entry, uint64_t Percentile) {
      58         232 :     return Entry.Cutoff < Percentile;
      59             :   };
      60         240 :   auto It = std::lower_bound(DS.begin(), DS.end(), Percentile, Compare);
      61             :   // The required percentile has to be <= one of the percentiles in the
      62             :   // detailed summary.
      63         160 :   if (It == DS.end())
      64           0 :     report_fatal_error("Desired percentile exceeds the maximum cutoff");
      65          80 :   return *It;
      66             : }
      67             : 
      68             : // The profile summary metadata may be attached either by the frontend or by
      69             : // any backend passes (IR level instrumentation, for example). This method
      70             : // checks if the Summary is null and if so checks if the summary metadata is now
      71             : // available in the module and parses it to get the Summary object. Returns true
      72             : // if a valid Summary is available.
      73     1179453 : bool ProfileSummaryInfo::computeSummary() {
      74     2358906 :   if (Summary)
      75             :     return true;
      76     1179170 :   auto *SummaryMD = M.getProfileSummary();
      77     1179170 :   if (!SummaryMD)
      78             :     return false;
      79          47 :   Summary.reset(ProfileSummary::getFromMD(SummaryMD));
      80             :   return true;
      81             : }
      82             : 
      83             : Optional<uint64_t>
      84         436 : ProfileSummaryInfo::getProfileCount(const Instruction *Inst,
      85             :                                     BlockFrequencyInfo *BFI) {
      86         436 :   if (!Inst)
      87             :     return None;
      88             :   assert((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
      89             :          "We can only get profile count for call/invoke instruction.");
      90          60 :   if (hasSampleProfile()) {
      91             :     // In sample PGO mode, check if there is a profile metadata on the
      92             :     // instruction. If it is present, determine hotness solely based on that,
      93             :     // since the sampled entry count may not be accurate. If there is no
      94             :     // annotated on the instruction, return None.
      95             :     uint64_t TotalCount;
      96          60 :     if (Inst->extractProfTotalWeight(TotalCount))
      97             :       return TotalCount;
      98             :     return None;
      99             :   }
     100         376 :   if (BFI)
     101         314 :     return BFI->getBlockProfileCount(Inst->getParent());
     102             :   return None;
     103             : }
     104             : 
     105             : /// Returns true if the function's entry is hot. If it returns false, it
     106             : /// either means it is not hot or it is unknown whether it is hot or not (for
     107             : /// example, no profile data is available).
     108      226437 : bool ProfileSummaryInfo::isFunctionEntryHot(const Function *F) {
     109      226437 :   if (!F || !computeSummary())
     110             :     return false;
     111          19 :   auto FunctionCount = F->getEntryCount();
     112             :   // FIXME: The heuristic used below for determining hotness is based on
     113             :   // preliminary SPEC tuning for inliner. This will eventually be a
     114             :   // convenience method that calls isHotCount.
     115          36 :   return FunctionCount && isHotCount(FunctionCount.getValue());
     116             : }
     117             : 
     118             : /// Returns true if the function's entry or total call edge count is hot.
     119             : /// If it returns false, it either means it is not hot or it is unknown
     120             : /// whether it is hot or not (for example, no profile data is available).
     121      136502 : bool ProfileSummaryInfo::isFunctionHotInCallGraph(const Function *F) {
     122      136502 :   if (!F || !computeSummary())
     123             :     return false;
     124          28 :   if (auto FunctionCount = F->getEntryCount())
     125          14 :     if (isHotCount(FunctionCount.getValue()))
     126           8 :       return true;
     127             : 
     128          12 :   uint64_t TotalCallCount = 0;
     129          59 :   for (const auto &BB : *F)
     130         167 :     for (const auto &I : BB)
     131         177 :       if (isa<CallInst>(I) || isa<InvokeInst>(I))
     132          38 :         if (auto CallCount = getProfileCount(&I, nullptr))
     133           8 :           TotalCallCount += CallCount.getValue();
     134          12 :   return isHotCount(TotalCallCount);
     135             : }
     136             : 
     137             : /// Returns true if the function's entry and total call edge count is cold.
     138             : /// If it returns false, it either means it is not cold or it is unknown
     139             : /// whether it is cold or not (for example, no profile data is available).
     140      136495 : bool ProfileSummaryInfo::isFunctionColdInCallGraph(const Function *F) {
     141      136495 :   if (!F || !computeSummary())
     142             :     return false;
     143          18 :   if (auto FunctionCount = F->getEntryCount())
     144           7 :     if (!isColdCount(FunctionCount.getValue()))
     145           0 :       return false;
     146             :   
     147           9 :   uint64_t TotalCallCount = 0;
     148          41 :   for (const auto &BB : *F)
     149         123 :     for (const auto &I : BB) 
     150         149 :       if (isa<CallInst>(I) || isa<InvokeInst>(I))
     151          26 :         if (auto CallCount = getProfileCount(&I, nullptr))
     152           4 :           TotalCallCount += CallCount.getValue();
     153           9 :   return isColdCount(TotalCallCount);
     154             : }
     155             : 
     156             : /// Returns true if the function's entry is a cold. If it returns false, it
     157             : /// either means it is not cold or it is unknown whether it is cold or not (for
     158             : /// example, no profile data is available).
     159      226580 : bool ProfileSummaryInfo::isFunctionEntryCold(const Function *F) {
     160      226580 :   if (!F)
     161             :     return false;
     162      226580 :   if (F->hasFnAttribute(Attribute::Cold))
     163             :     return true;
     164      226563 :   if (!computeSummary())
     165             :     return false;
     166          12 :   auto FunctionCount = F->getEntryCount();
     167             :   // FIXME: The heuristic used below for determining coldness is based on
     168             :   // preliminary SPEC tuning for inliner. This will eventually be a
     169             :   // convenience method that calls isHotCount.
     170          22 :   return FunctionCount && isColdCount(FunctionCount.getValue());
     171             : }
     172             : 
     173             : /// Compute the hot and cold thresholds.
     174          76 : void ProfileSummaryInfo::computeThresholds() {
     175          76 :   if (!computeSummary())
     176             :     return;
     177         120 :   auto &DetailedSummary = Summary->getDetailedSummary();
     178             :   auto &HotEntry =
     179          40 :       getEntryForPercentile(DetailedSummary, ProfileSummaryCutoffHot);
     180          80 :   HotCountThreshold = HotEntry.MinCount;
     181             :   auto &ColdEntry =
     182          40 :       getEntryForPercentile(DetailedSummary, ProfileSummaryCutoffCold);
     183          80 :   ColdCountThreshold = ColdEntry.MinCount;
     184          40 :   HasHugeWorkingSetSize =
     185          80 :       HotEntry.NumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
     186             : }
     187             : 
     188          23 : bool ProfileSummaryInfo::hasHugeWorkingSetSize() {
     189          23 :   if (!HasHugeWorkingSetSize)
     190          20 :     computeThresholds();
     191          26 :   return HasHugeWorkingSetSize && HasHugeWorkingSetSize.getValue();
     192             : }
     193             : 
     194         135 : bool ProfileSummaryInfo::isHotCount(uint64_t C) {
     195         135 :   if (!HotCountThreshold)
     196          48 :     computeThresholds();
     197         262 :   return HotCountThreshold && C >= HotCountThreshold.getValue();
     198             : }
     199             : 
     200          66 : bool ProfileSummaryInfo::isColdCount(uint64_t C) {
     201          66 :   if (!ColdCountThreshold)
     202           8 :     computeThresholds();
     203         124 :   return ColdCountThreshold && C <= ColdCountThreshold.getValue();
     204             : }
     205             : 
     206           9 : bool ProfileSummaryInfo::isHotBB(const BasicBlock *B, BlockFrequencyInfo *BFI) {
     207          18 :   auto Count = BFI->getBlockProfileCount(B);
     208          27 :   return Count && isHotCount(*Count);
     209             : }
     210             : 
     211           1 : bool ProfileSummaryInfo::isColdBB(const BasicBlock *B,
     212             :                                   BlockFrequencyInfo *BFI) {
     213           2 :   auto Count = BFI->getBlockProfileCount(B);
     214           3 :   return Count && isColdCount(*Count);
     215             : }
     216             : 
     217          39 : bool ProfileSummaryInfo::isHotCallSite(const CallSite &CS,
     218             :                                        BlockFrequencyInfo *BFI) {
     219         117 :   auto C = getProfileCount(CS.getInstruction(), BFI);
     220         106 :   return C && isHotCount(*C);
     221             : }
     222             : 
     223          21 : bool ProfileSummaryInfo::isColdCallSite(const CallSite &CS,
     224             :                                         BlockFrequencyInfo *BFI) {
     225          63 :   auto C = getProfileCount(CS.getInstruction(), BFI);
     226          21 :   if (C)
     227          11 :     return isColdCount(*C);
     228             : 
     229             :   // In SamplePGO, if the caller has been sampled, and there is no profile
     230             :   // annotatedon the callsite, we consider the callsite as cold.
     231             :   // If there is no profile for the caller, and we know the profile is
     232             :   // accurate, we consider the callsite as cold.
     233          18 :   return (hasSampleProfile() &&
     234          24 :           (CS.getCaller()->getEntryCount() || ProfileSampleAccurate ||
     235           9 :            CS.getCaller()->hasFnAttribute("profile-sample-accurate")));
     236             : }
     237             : 
     238      369315 : INITIALIZE_PASS(ProfileSummaryInfoWrapperPass, "profile-summary-info",
     239             :                 "Profile summary info", false, true)
     240             : 
     241       21998 : ProfileSummaryInfoWrapperPass::ProfileSummaryInfoWrapperPass()
     242       65994 :     : ImmutablePass(ID) {
     243       21998 :   initializeProfileSummaryInfoWrapperPassPass(*PassRegistry::getPassRegistry());
     244       21998 : }
     245             : 
     246       22002 : bool ProfileSummaryInfoWrapperPass::doInitialization(Module &M) {
     247       66006 :   PSI.reset(new ProfileSummaryInfo(M));
     248       22002 :   return false;
     249             : }
     250             : 
     251       21903 : bool ProfileSummaryInfoWrapperPass::doFinalization(Module &M) {
     252       43805 :   PSI.reset();
     253       21902 :   return false;
     254             : }
     255             : 
     256             : AnalysisKey ProfileSummaryAnalysis::Key;
     257         119 : ProfileSummaryInfo ProfileSummaryAnalysis::run(Module &M,
     258             :                                                ModuleAnalysisManager &) {
     259         119 :   return ProfileSummaryInfo(M);
     260             : }
     261             : 
     262           1 : PreservedAnalyses ProfileSummaryPrinterPass::run(Module &M,
     263             :                                                  ModuleAnalysisManager &AM) {
     264           1 :   ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
     265             : 
     266           2 :   OS << "Functions in " << M.getName() << " with hot/cold annotations: \n";
     267           6 :   for (auto &F : M) {
     268           3 :     OS << F.getName();
     269           3 :     if (PSI.isFunctionEntryHot(&F))
     270           2 :       OS << " :hot entry ";
     271           1 :     else if (PSI.isFunctionEntryCold(&F))
     272           1 :       OS << " :cold entry ";
     273           3 :     OS << "\n";
     274             :   }
     275           1 :   return PreservedAnalyses::all();
     276             : }
     277             : 
     278      216918 : char ProfileSummaryInfoWrapperPass::ID = 0;

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