llvm-project

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//===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains a pass that provides access to the global profile summary
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// information.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/ProfileSummaryInfo.h"
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#include "llvm/Analysis/BlockFrequencyInfo.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/ProfileSummary.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/ProfileData/ProfileCommon.h"
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#include "llvm/Support/CommandLine.h"
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#include <optional>
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using namespace llvm;
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static cl::opt<bool> PartialProfile(
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    "partial-profile", cl::Hidden, cl::init(false),
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    cl::desc("Specify the current profile is used as a partial profile."));
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cl::opt<bool> ScalePartialSampleProfileWorkingSetSize(
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    "scale-partial-sample-profile-working-set-size", cl::Hidden, cl::init(true),
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    cl::desc(
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        "If true, scale the working set size of the partial sample profile "
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        "by the partial profile ratio to reflect the size of the program "
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        "being compiled."));
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static cl::opt<double> PartialSampleProfileWorkingSetSizeScaleFactor(
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    "partial-sample-profile-working-set-size-scale-factor", cl::Hidden,
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    cl::init(0.008),
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    cl::desc("The scale factor used to scale the working set size of the "
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             "partial sample profile along with the partial profile ratio. "
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             "This includes the factor of the profile counter per block "
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             "and the factor to scale the working set size to use the same "
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             "shared thresholds as PGO."));
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// The profile summary metadata may be attached either by the frontend or by
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// any backend passes (IR level instrumentation, for example). This method
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// checks if the Summary is null and if so checks if the summary metadata is now
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// available in the module and parses it to get the Summary object.
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void ProfileSummaryInfo::refresh() {
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  if (hasProfileSummary())
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    return;
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  // First try to get context sensitive ProfileSummary.
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  auto *SummaryMD = M->getProfileSummary(/* IsCS */ true);
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  if (SummaryMD)
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    Summary.reset(ProfileSummary::getFromMD(SummaryMD));
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  if (!hasProfileSummary()) {
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    // This will actually return PSK_Instr or PSK_Sample summary.
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    SummaryMD = M->getProfileSummary(/* IsCS */ false);
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    if (SummaryMD)
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      Summary.reset(ProfileSummary::getFromMD(SummaryMD));
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  }
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  if (!hasProfileSummary())
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    return;
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  computeThresholds();
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}
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std::optional<uint64_t> ProfileSummaryInfo::getProfileCount(
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    const CallBase &Call, BlockFrequencyInfo *BFI, bool AllowSynthetic) const {
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  assert((isa<CallInst>(Call) || isa<InvokeInst>(Call)) &&
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         "We can only get profile count for call/invoke instruction.");
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  if (hasSampleProfile()) {
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    // In sample PGO mode, check if there is a profile metadata on the
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    // instruction. If it is present, determine hotness solely based on that,
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    // since the sampled entry count may not be accurate. If there is no
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    // annotated on the instruction, return std::nullopt.
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    uint64_t TotalCount;
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    if (Call.extractProfTotalWeight(TotalCount))
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      return TotalCount;
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    return std::nullopt;
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  }
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  if (BFI)
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    return BFI->getBlockProfileCount(Call.getParent(), AllowSynthetic);
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  return std::nullopt;
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}
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bool ProfileSummaryInfo::isFunctionHotnessUnknown(const Function &F) const {
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  assert(hasPartialSampleProfile() && "Expect partial sample profile");
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  return !F.getEntryCount();
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}
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/// Returns true if the function's entry is a cold. If it returns false, it
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/// either means it is not cold or it is unknown whether it is cold or not (for
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/// example, no profile data is available).
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bool ProfileSummaryInfo::isFunctionEntryCold(const Function *F) const {
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  if (!F)
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    return false;
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  if (F->hasFnAttribute(Attribute::Cold))
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    return true;
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  if (!hasProfileSummary())
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    return false;
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  auto FunctionCount = F->getEntryCount();
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  // FIXME: The heuristic used below for determining coldness is based on
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  // preliminary SPEC tuning for inliner. This will eventually be a
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  // convenience method that calls isHotCount.
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  return FunctionCount && isColdCount(FunctionCount->getCount());
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}
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/// Compute the hot and cold thresholds.
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void ProfileSummaryInfo::computeThresholds() {
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  auto &DetailedSummary = Summary->getDetailedSummary();
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  auto &HotEntry = ProfileSummaryBuilder::getEntryForPercentile(
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      DetailedSummary, ProfileSummaryCutoffHot);
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  HotCountThreshold =
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      ProfileSummaryBuilder::getHotCountThreshold(DetailedSummary);
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  ColdCountThreshold =
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      ProfileSummaryBuilder::getColdCountThreshold(DetailedSummary);
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  assert(ColdCountThreshold <= HotCountThreshold &&
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         "Cold count threshold cannot exceed hot count threshold!");
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  if (!hasPartialSampleProfile() || !ScalePartialSampleProfileWorkingSetSize) {
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    HasHugeWorkingSetSize =
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        HotEntry.NumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
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    HasLargeWorkingSetSize =
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        HotEntry.NumCounts > ProfileSummaryLargeWorkingSetSizeThreshold;
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  } else {
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    // Scale the working set size of the partial sample profile to reflect the
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    // size of the program being compiled.
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    double PartialProfileRatio = Summary->getPartialProfileRatio();
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    uint64_t ScaledHotEntryNumCounts =
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        static_cast<uint64_t>(HotEntry.NumCounts * PartialProfileRatio *
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                              PartialSampleProfileWorkingSetSizeScaleFactor);
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    HasHugeWorkingSetSize =
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        ScaledHotEntryNumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
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    HasLargeWorkingSetSize =
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        ScaledHotEntryNumCounts > ProfileSummaryLargeWorkingSetSizeThreshold;
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  }
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}
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std::optional<uint64_t>
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ProfileSummaryInfo::computeThreshold(int PercentileCutoff) const {
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  if (!hasProfileSummary())
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    return std::nullopt;
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  auto iter = ThresholdCache.find(PercentileCutoff);
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  if (iter != ThresholdCache.end()) {
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    return iter->second;
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  }
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  auto &DetailedSummary = Summary->getDetailedSummary();
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  auto &Entry = ProfileSummaryBuilder::getEntryForPercentile(DetailedSummary,
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                                                             PercentileCutoff);
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  uint64_t CountThreshold = Entry.MinCount;
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  ThresholdCache[PercentileCutoff] = CountThreshold;
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  return CountThreshold;
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}
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bool ProfileSummaryInfo::hasHugeWorkingSetSize() const {
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  return HasHugeWorkingSetSize && *HasHugeWorkingSetSize;
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}
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bool ProfileSummaryInfo::hasLargeWorkingSetSize() const {
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  return HasLargeWorkingSetSize && *HasLargeWorkingSetSize;
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}
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bool ProfileSummaryInfo::isHotCount(uint64_t C) const {
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  return HotCountThreshold && C >= *HotCountThreshold;
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}
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bool ProfileSummaryInfo::isColdCount(uint64_t C) const {
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  return ColdCountThreshold && C <= *ColdCountThreshold;
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}
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template <bool isHot>
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bool ProfileSummaryInfo::isHotOrColdCountNthPercentile(int PercentileCutoff,
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                                                       uint64_t C) const {
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  auto CountThreshold = computeThreshold(PercentileCutoff);
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  if (isHot)
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    return CountThreshold && C >= *CountThreshold;
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  else
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    return CountThreshold && C <= *CountThreshold;
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}
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bool ProfileSummaryInfo::isHotCountNthPercentile(int PercentileCutoff,
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                                                 uint64_t C) const {
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  return isHotOrColdCountNthPercentile<true>(PercentileCutoff, C);
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}
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bool ProfileSummaryInfo::isColdCountNthPercentile(int PercentileCutoff,
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                                                  uint64_t C) const {
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  return isHotOrColdCountNthPercentile<false>(PercentileCutoff, C);
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}
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uint64_t ProfileSummaryInfo::getOrCompHotCountThreshold() const {
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  return HotCountThreshold.value_or(UINT64_MAX);
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}
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uint64_t ProfileSummaryInfo::getOrCompColdCountThreshold() const {
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  return ColdCountThreshold.value_or(0);
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}
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bool ProfileSummaryInfo::isHotCallSite(const CallBase &CB,
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                                       BlockFrequencyInfo *BFI) const {
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  auto C = getProfileCount(CB, BFI);
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  return C && isHotCount(*C);
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}
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bool ProfileSummaryInfo::isColdCallSite(const CallBase &CB,
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                                        BlockFrequencyInfo *BFI) const {
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  auto C = getProfileCount(CB, BFI);
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  if (C)
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    return isColdCount(*C);
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  // In SamplePGO, if the caller has been sampled, and there is no profile
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  // annotated on the callsite, we consider the callsite as cold.
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  return hasSampleProfile() && CB.getCaller()->hasProfileData();
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}
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bool ProfileSummaryInfo::hasPartialSampleProfile() const {
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  return hasProfileSummary() &&
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         Summary->getKind() == ProfileSummary::PSK_Sample &&
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         (PartialProfile || Summary->isPartialProfile());
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}
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INITIALIZE_PASS(ProfileSummaryInfoWrapperPass, "profile-summary-info",
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                "Profile summary info", false, true)
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ProfileSummaryInfoWrapperPass::ProfileSummaryInfoWrapperPass()
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    : ImmutablePass(ID) {
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  initializeProfileSummaryInfoWrapperPassPass(*PassRegistry::getPassRegistry());
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}
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bool ProfileSummaryInfoWrapperPass::doInitialization(Module &M) {
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  PSI.reset(new ProfileSummaryInfo(M));
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  return false;
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}
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bool ProfileSummaryInfoWrapperPass::doFinalization(Module &M) {
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  PSI.reset();
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  return false;
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}
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AnalysisKey ProfileSummaryAnalysis::Key;
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ProfileSummaryInfo ProfileSummaryAnalysis::run(Module &M,
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                                               ModuleAnalysisManager &) {
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  return ProfileSummaryInfo(M);
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}
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PreservedAnalyses ProfileSummaryPrinterPass::run(Module &M,
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                                                 ModuleAnalysisManager &AM) {
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  ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
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  OS << "Functions in " << M.getName() << " with hot/cold annotations: \n";
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  for (auto &F : M) {
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    OS << F.getName();
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    if (PSI.isFunctionEntryHot(&F))
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      OS << " :hot entry ";
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    else if (PSI.isFunctionEntryCold(&F))
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      OS << " :cold entry ";
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    OS << "\n";
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  }
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  return PreservedAnalyses::all();
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}
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char ProfileSummaryInfoWrapperPass::ID = 0;
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