246 lines
9.1 KiB
C++
246 lines
9.1 KiB
C++
//===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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/CallSite.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/ProfileSummary.h"
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using namespace llvm;
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// The following two parameters determine the threshold for a count to be
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// considered hot/cold. These two parameters are percentile values (multiplied
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// by 10000). If the counts are sorted in descending order, the minimum count to
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// reach ProfileSummaryCutoffHot gives the threshold to determine a hot count.
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// Similarly, the minimum count to reach ProfileSummaryCutoffCold gives the
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// threshold for determining cold count (everything <= this threshold is
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// considered cold).
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static cl::opt<int> ProfileSummaryCutoffHot(
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"profile-summary-cutoff-hot", cl::Hidden, cl::init(999000), cl::ZeroOrMore,
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cl::desc("A count is hot if it exceeds the minimum count to"
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" reach this percentile of total counts."));
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static cl::opt<int> ProfileSummaryCutoffCold(
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"profile-summary-cutoff-cold", cl::Hidden, cl::init(999999), cl::ZeroOrMore,
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cl::desc("A count is cold if it is below the minimum count"
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" to reach this percentile of total counts."));
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// Find the minimum count to reach a desired percentile of counts.
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static uint64_t getMinCountForPercentile(SummaryEntryVector &DS,
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uint64_t Percentile) {
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auto Compare = [](const ProfileSummaryEntry &Entry, uint64_t Percentile) {
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return Entry.Cutoff < Percentile;
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};
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auto It = std::lower_bound(DS.begin(), DS.end(), Percentile, Compare);
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// The required percentile has to be <= one of the percentiles in the
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// detailed summary.
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if (It == DS.end())
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report_fatal_error("Desired percentile exceeds the maximum cutoff");
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return It->MinCount;
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}
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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. Returns true
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// if a valid Summary is available.
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bool ProfileSummaryInfo::computeSummary() {
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if (Summary)
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return true;
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auto *SummaryMD = M.getProfileSummary();
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if (!SummaryMD)
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return false;
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Summary.reset(ProfileSummary::getFromMD(SummaryMD));
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return true;
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}
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Optional<uint64_t>
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ProfileSummaryInfo::getProfileCount(const Instruction *Inst,
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BlockFrequencyInfo *BFI) {
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if (!Inst)
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return None;
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assert((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
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"We can only get profile count for call/invoke instruction.");
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if (computeSummary() && Summary->getKind() == ProfileSummary::PSK_Sample) {
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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.
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uint64_t TotalCount;
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if (Inst->extractProfTotalWeight(TotalCount))
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return TotalCount;
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}
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if (BFI)
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return BFI->getBlockProfileCount(Inst->getParent());
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return None;
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}
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/// Returns true if the function's entry is hot. If it returns false, it
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/// either means it is not hot or it is unknown whether it is hot or not (for
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/// example, no profile data is available).
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bool ProfileSummaryInfo::isFunctionEntryHot(const Function *F) {
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if (!F || !computeSummary())
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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 hotness 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 && isHotCount(FunctionCount.getValue());
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}
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/// Returns true if the function's entry or total call edge count is hot.
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/// If it returns false, it either means it is not hot or it is unknown
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/// whether it is hot or not (for example, no profile data is available).
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bool ProfileSummaryInfo::isFunctionHotInCallGraph(const Function *F) {
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if (!F || !computeSummary())
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return false;
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if (auto FunctionCount = F->getEntryCount())
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if (isHotCount(FunctionCount.getValue()))
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return true;
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uint64_t TotalCallCount = 0;
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for (const auto &BB : *F)
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for (const auto &I : BB)
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if (isa<CallInst>(I) || isa<InvokeInst>(I))
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if (auto CallCount = getProfileCount(&I, nullptr))
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TotalCallCount += CallCount.getValue();
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return isHotCount(TotalCallCount);
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}
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/// Returns true if the function's entry and total call edge count is cold.
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/// If it returns false, it either means it is not cold or it is unknown
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/// whether it is cold or not (for example, no profile data is available).
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bool ProfileSummaryInfo::isFunctionColdInCallGraph(const Function *F) {
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if (!F || !computeSummary())
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return false;
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if (auto FunctionCount = F->getEntryCount())
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if (!isColdCount(FunctionCount.getValue()))
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return false;
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uint64_t TotalCallCount = 0;
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for (const auto &BB : *F)
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for (const auto &I : BB)
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if (isa<CallInst>(I) || isa<InvokeInst>(I))
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if (auto CallCount = getProfileCount(&I, nullptr))
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TotalCallCount += CallCount.getValue();
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return isColdCount(TotalCallCount);
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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) {
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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 (!computeSummary())
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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.getValue());
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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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if (!computeSummary())
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return;
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auto &DetailedSummary = Summary->getDetailedSummary();
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HotCountThreshold =
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getMinCountForPercentile(DetailedSummary, ProfileSummaryCutoffHot);
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ColdCountThreshold =
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getMinCountForPercentile(DetailedSummary, ProfileSummaryCutoffCold);
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}
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bool ProfileSummaryInfo::isHotCount(uint64_t C) {
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if (!HotCountThreshold)
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computeThresholds();
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return HotCountThreshold && C >= HotCountThreshold.getValue();
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}
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bool ProfileSummaryInfo::isColdCount(uint64_t C) {
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if (!ColdCountThreshold)
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computeThresholds();
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return ColdCountThreshold && C <= ColdCountThreshold.getValue();
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}
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bool ProfileSummaryInfo::isHotBB(const BasicBlock *B, BlockFrequencyInfo *BFI) {
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auto Count = BFI->getBlockProfileCount(B);
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return Count && isHotCount(*Count);
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}
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bool ProfileSummaryInfo::isColdBB(const BasicBlock *B,
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BlockFrequencyInfo *BFI) {
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auto Count = BFI->getBlockProfileCount(B);
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return Count && isColdCount(*Count);
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}
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bool ProfileSummaryInfo::isHotCallSite(const CallSite &CS,
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BlockFrequencyInfo *BFI) {
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auto C = getProfileCount(CS.getInstruction(), BFI);
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return C && isHotCount(*C);
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}
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bool ProfileSummaryInfo::isColdCallSite(const CallSite &CS,
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BlockFrequencyInfo *BFI) {
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auto C = getProfileCount(CS.getInstruction(), BFI);
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return C && isColdCount(*C);
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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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