forked from OSchip/llvm-project
326 lines
12 KiB
C++
326 lines
12 KiB
C++
//===- 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/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(990000), 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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static cl::opt<unsigned> ProfileSummaryHugeWorkingSetSizeThreshold(
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"profile-summary-huge-working-set-size-threshold", cl::Hidden,
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cl::init(15000), cl::ZeroOrMore,
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cl::desc("The code working set size is considered huge if the number of"
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" blocks required to reach the -profile-summary-cutoff-hot"
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" percentile exceeds this count."));
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// The next two options override the counts derived from summary computation and
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// are useful for debugging purposes.
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static cl::opt<int> ProfileSummaryHotCount(
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"profile-summary-hot-count", cl::ReallyHidden, cl::ZeroOrMore,
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cl::desc("A fixed hot count that overrides the count derived from"
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" profile-summary-cutoff-hot"));
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static cl::opt<int> ProfileSummaryColdCount(
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"profile-summary-cold-count", cl::ReallyHidden, cl::ZeroOrMore,
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cl::desc("A fixed cold count that overrides the count derived from"
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" profile-summary-cutoff-cold"));
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// Find the summary entry for a desired percentile of counts.
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static const ProfileSummaryEntry &getEntryForPercentile(SummaryEntryVector &DS,
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uint64_t Percentile) {
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auto It = llvm::bsearch(DS, [=](const ProfileSummaryEntry &Entry) {
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return Percentile <= Entry.Cutoff;
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});
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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;
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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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// 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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return true;
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}
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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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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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bool AllowSynthetic) {
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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 (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 None.
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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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return None;
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}
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if (BFI)
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return BFI->getBlockProfileCount(Inst->getParent(), AllowSynthetic);
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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.getCount());
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}
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/// Returns true if the function contains hot code. This can include a hot
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/// function entry count, hot basic block, or (in the case of Sample PGO)
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/// hot total call edge count.
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/// If it returns false, it either means it is not hot or it is unknown
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/// (for example, no profile data is available).
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bool ProfileSummaryInfo::isFunctionHotInCallGraph(const Function *F,
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BlockFrequencyInfo &BFI) {
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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.getCount()))
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return true;
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if (hasSampleProfile()) {
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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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if (isHotCount(TotalCallCount))
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return true;
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}
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for (const auto &BB : *F)
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if (isHotBlock(&BB, &BFI))
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return true;
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return false;
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}
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/// Returns true if the function only contains cold code. This means that
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/// the function entry and blocks are all cold, and (in the case of Sample PGO)
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/// the 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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/// (for example, no profile data is available).
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bool ProfileSummaryInfo::isFunctionColdInCallGraph(const Function *F,
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BlockFrequencyInfo &BFI) {
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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.getCount()))
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return false;
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if (hasSampleProfile()) {
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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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if (!isColdCount(TotalCallCount))
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return false;
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}
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for (const auto &BB : *F)
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if (!isColdBlock(&BB, &BFI))
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return false;
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return true;
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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.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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if (!computeSummary())
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return;
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auto &DetailedSummary = Summary->getDetailedSummary();
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auto &HotEntry =
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getEntryForPercentile(DetailedSummary, ProfileSummaryCutoffHot);
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HotCountThreshold = HotEntry.MinCount;
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if (ProfileSummaryHotCount.getNumOccurrences() > 0)
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HotCountThreshold = ProfileSummaryHotCount;
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auto &ColdEntry =
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getEntryForPercentile(DetailedSummary, ProfileSummaryCutoffCold);
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ColdCountThreshold = ColdEntry.MinCount;
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if (ProfileSummaryColdCount.getNumOccurrences() > 0)
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ColdCountThreshold = ProfileSummaryColdCount;
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assert(ColdCountThreshold <= HotCountThreshold &&
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"Cold count threshold cannot exceed hot count threshold!");
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HasHugeWorkingSetSize =
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HotEntry.NumCounts > ProfileSummaryHugeWorkingSetSizeThreshold;
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}
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bool ProfileSummaryInfo::hasHugeWorkingSetSize() {
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if (!HasHugeWorkingSetSize)
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computeThresholds();
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return HasHugeWorkingSetSize && HasHugeWorkingSetSize.getValue();
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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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uint64_t ProfileSummaryInfo::getOrCompHotCountThreshold() {
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if (!HotCountThreshold)
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computeThresholds();
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return HotCountThreshold ? HotCountThreshold.getValue() : UINT64_MAX;
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}
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uint64_t ProfileSummaryInfo::getOrCompColdCountThreshold() {
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if (!ColdCountThreshold)
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computeThresholds();
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return ColdCountThreshold ? ColdCountThreshold.getValue() : 0;
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}
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bool ProfileSummaryInfo::isHotBlock(const BasicBlock *BB, BlockFrequencyInfo *BFI) {
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auto Count = BFI->getBlockProfileCount(BB);
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return Count && isHotCount(*Count);
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}
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bool ProfileSummaryInfo::isColdBlock(const BasicBlock *BB,
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BlockFrequencyInfo *BFI) {
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auto Count = BFI->getBlockProfileCount(BB);
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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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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() && CS.getCaller()->hasProfileData();
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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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