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//===- SampleProfile.cpp - Incorporate sample profiles into the IR --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the SampleProfileLoader transformation. This pass
// reads a profile file generated by a sampling profiler (e.g. Linux Perf -
// http://perf.wiki.kernel.org/) and generates IR metadata to reflect the
// profile information in the given profile.
//
// This pass generates branch weight annotations on the IR:
//
// - prof: Represents branch weights. This annotation is added to branches
// to indicate the weights of each edge coming out of the branch.
// The weight of each edge is the weight of the target block for
// that edge. The weight of a block B is computed as the maximum
// number of samples found in B.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/SampleProfile.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/PriorityQueue.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
#include "llvm/Analysis/InlineAdvisor.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/LazyCallGraph.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/ReplayInlineAdvisor.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/IR/PseudoProbe.h"
#include "llvm/IR/ValueSymbolTable.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/ProfileData/SampleProf.h"
#include "llvm/ProfileData/SampleProfReader.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/ProfiledCallGraph.h"
#include "llvm/Transforms/IPO/SampleContextTracker.h"
#include "llvm/Transforms/IPO/SampleProfileMatcher.h"
#include "llvm/Transforms/IPO/SampleProfileProbe.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/CallPromotionUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/MisExpect.h"
#include "llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h"
#include "llvm/Transforms/Utils/SampleProfileLoaderBaseUtil.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <functional>
#include <limits>
#include <map>
#include <memory>
#include <queue>
#include <string>
#include <system_error>
#include <utility>
#include <vector>
using namespace llvm;
using namespace sampleprof;
using namespace llvm::sampleprofutil;
using ProfileCount = Function::ProfileCount;
#define DEBUG_TYPE "sample-profile"
#define CSINLINE_DEBUG DEBUG_TYPE "-inline"
STATISTIC(NumCSInlined,
"Number of functions inlined with context sensitive profile");
STATISTIC(NumCSNotInlined,
"Number of functions not inlined with context sensitive profile");
STATISTIC(NumMismatchedProfile,
"Number of functions with CFG mismatched profile");
STATISTIC(NumMatchedProfile, "Number of functions with CFG matched profile");
STATISTIC(NumDuplicatedInlinesite,
"Number of inlined callsites with a partial distribution factor");
STATISTIC(NumCSInlinedHitMinLimit,
"Number of functions with FDO inline stopped due to min size limit");
STATISTIC(NumCSInlinedHitMaxLimit,
"Number of functions with FDO inline stopped due to max size limit");
STATISTIC(
NumCSInlinedHitGrowthLimit,
"Number of functions with FDO inline stopped due to growth size limit");
// Command line option to specify the file to read samples from. This is
// mainly used for debugging.
static cl::opt<std::string> SampleProfileFile(
"sample-profile-file", cl::init(""), cl::value_desc("filename"),
cl::desc("Profile file loaded by -sample-profile"), cl::Hidden);
// The named file contains a set of transformations that may have been applied
// to the symbol names between the program from which the sample data was
// collected and the current program's symbols.
static cl::opt<std::string> SampleProfileRemappingFile(
"sample-profile-remapping-file", cl::init(""), cl::value_desc("filename"),
cl::desc("Profile remapping file loaded by -sample-profile"), cl::Hidden);
cl::opt<bool> SalvageStaleProfile(
"salvage-stale-profile", cl::Hidden, cl::init(false),
cl::desc("Salvage stale profile by fuzzy matching and use the remapped "
"location for sample profile query."));
cl::opt<bool> ReportProfileStaleness(
"report-profile-staleness", cl::Hidden, cl::init(false),
cl::desc("Compute and report stale profile statistical metrics."));
cl::opt<bool> PersistProfileStaleness(
"persist-profile-staleness", cl::Hidden, cl::init(false),
cl::desc("Compute stale profile statistical metrics and write it into the "
"native object file(.llvm_stats section)."));
static cl::opt<bool> ProfileSampleAccurate(
"profile-sample-accurate", cl::Hidden, cl::init(false),
cl::desc("If the sample profile is accurate, we will mark all un-sampled "
"callsite and function as having 0 samples. Otherwise, treat "
"un-sampled callsites and functions conservatively as unknown. "));
static cl::opt<bool> ProfileSampleBlockAccurate(
"profile-sample-block-accurate", cl::Hidden, cl::init(false),
cl::desc("If the sample profile is accurate, we will mark all un-sampled "
"branches and calls as having 0 samples. Otherwise, treat "
"them conservatively as unknown. "));
static cl::opt<bool> ProfileAccurateForSymsInList(
"profile-accurate-for-symsinlist", cl::Hidden, cl::init(true),
cl::desc("For symbols in profile symbol list, regard their profiles to "
"be accurate. It may be overriden by profile-sample-accurate. "));
static cl::opt<bool> ProfileMergeInlinee(
"sample-profile-merge-inlinee", cl::Hidden, cl::init(true),
cl::desc("Merge past inlinee's profile to outline version if sample "
"profile loader decided not to inline a call site. It will "
"only be enabled when top-down order of profile loading is "
"enabled. "));
static cl::opt<bool> ProfileTopDownLoad(
"sample-profile-top-down-load", cl::Hidden, cl::init(true),
cl::desc("Do profile annotation and inlining for functions in top-down "
"order of call graph during sample profile loading. It only "
"works for new pass manager. "));
static cl::opt<bool>
UseProfiledCallGraph("use-profiled-call-graph", cl::init(true), cl::Hidden,
cl::desc("Process functions in a top-down order "
"defined by the profiled call graph when "
"-sample-profile-top-down-load is on."));
static cl::opt<bool> ProfileSizeInline(
"sample-profile-inline-size", cl::Hidden, cl::init(false),
cl::desc("Inline cold call sites in profile loader if it's beneficial "
"for code size."));
// Since profiles are consumed by many passes, turning on this option has
// side effects. For instance, pre-link SCC inliner would see merged profiles
// and inline the hot functions (that are skipped in this pass).
static cl::opt<bool> DisableSampleLoaderInlining(
"disable-sample-loader-inlining", cl::Hidden, cl::init(false),
cl::desc("If true, artifically skip inline transformation in sample-loader "
"pass, and merge (or scale) profiles (as configured by "
"--sample-profile-merge-inlinee)."));
namespace llvm {
cl::opt<bool>
SortProfiledSCC("sort-profiled-scc-member", cl::init(true), cl::Hidden,
cl::desc("Sort profiled recursion by edge weights."));
cl::opt<int> ProfileInlineGrowthLimit(
"sample-profile-inline-growth-limit", cl::Hidden, cl::init(12),
cl::desc("The size growth ratio limit for proirity-based sample profile "
"loader inlining."));
cl::opt<int> ProfileInlineLimitMin(
"sample-profile-inline-limit-min", cl::Hidden, cl::init(100),
cl::desc("The lower bound of size growth limit for "
"proirity-based sample profile loader inlining."));
cl::opt<int> ProfileInlineLimitMax(
"sample-profile-inline-limit-max", cl::Hidden, cl::init(10000),
cl::desc("The upper bound of size growth limit for "
"proirity-based sample profile loader inlining."));
cl::opt<int> SampleHotCallSiteThreshold(
"sample-profile-hot-inline-threshold", cl::Hidden, cl::init(3000),
cl::desc("Hot callsite threshold for proirity-based sample profile loader "
"inlining."));
cl::opt<int> SampleColdCallSiteThreshold(
"sample-profile-cold-inline-threshold", cl::Hidden, cl::init(45),
cl::desc("Threshold for inlining cold callsites"));
} // namespace llvm
static cl::opt<unsigned> ProfileICPRelativeHotness(
"sample-profile-icp-relative-hotness", cl::Hidden, cl::init(25),
cl::desc(
"Relative hotness percentage threshold for indirect "
"call promotion in proirity-based sample profile loader inlining."));
static cl::opt<unsigned> ProfileICPRelativeHotnessSkip(
"sample-profile-icp-relative-hotness-skip", cl::Hidden, cl::init(1),
cl::desc(
"Skip relative hotness check for ICP up to given number of targets."));
static cl::opt<unsigned> HotFuncCutoffForStalenessError(
"hot-func-cutoff-for-staleness-error", cl::Hidden, cl::init(800000),
cl::desc("A function is considered hot for staleness error check if its "
"total sample count is above the specified percentile"));
static cl::opt<unsigned> MinfuncsForStalenessError(
"min-functions-for-staleness-error", cl::Hidden, cl::init(50),
cl::desc("Skip the check if the number of hot functions is smaller than "
"the specified number."));
static cl::opt<unsigned> PrecentMismatchForStalenessError(
"precent-mismatch-for-staleness-error", cl::Hidden, cl::init(80),
cl::desc("Reject the profile if the mismatch percent is higher than the "
"given number."));
static cl::opt<bool> CallsitePrioritizedInline(
"sample-profile-prioritized-inline", cl::Hidden,
cl::desc("Use call site prioritized inlining for sample profile loader."
"Currently only CSSPGO is supported."));
static cl::opt<bool> UsePreInlinerDecision(
"sample-profile-use-preinliner", cl::Hidden,
cl::desc("Use the preinliner decisions stored in profile context."));
static cl::opt<bool> AllowRecursiveInline(
"sample-profile-recursive-inline", cl::Hidden,
cl::desc("Allow sample loader inliner to inline recursive calls."));
static cl::opt<bool> RemoveProbeAfterProfileAnnotation(
"sample-profile-remove-probe", cl::Hidden, cl::init(false),
cl::desc("Remove pseudo-probe after sample profile annotation."));
static cl::opt<std::string> ProfileInlineReplayFile(
"sample-profile-inline-replay", cl::init(""), cl::value_desc("filename"),
cl::desc(
"Optimization remarks file containing inline remarks to be replayed "
"by inlining from sample profile loader."),
cl::Hidden);
static cl::opt<ReplayInlinerSettings::Scope> ProfileInlineReplayScope(
"sample-profile-inline-replay-scope",
cl::init(ReplayInlinerSettings::Scope::Function),
cl::values(clEnumValN(ReplayInlinerSettings::Scope::Function, "Function",
"Replay on functions that have remarks associated "
"with them (default)"),
clEnumValN(ReplayInlinerSettings::Scope::Module, "Module",
"Replay on the entire module")),
cl::desc("Whether inline replay should be applied to the entire "
"Module or just the Functions (default) that are present as "
"callers in remarks during sample profile inlining."),
cl::Hidden);
static cl::opt<ReplayInlinerSettings::Fallback> ProfileInlineReplayFallback(
"sample-profile-inline-replay-fallback",
cl::init(ReplayInlinerSettings::Fallback::Original),
cl::values(
clEnumValN(
ReplayInlinerSettings::Fallback::Original, "Original",
"All decisions not in replay send to original advisor (default)"),
clEnumValN(ReplayInlinerSettings::Fallback::AlwaysInline,
"AlwaysInline", "All decisions not in replay are inlined"),
clEnumValN(ReplayInlinerSettings::Fallback::NeverInline, "NeverInline",
"All decisions not in replay are not inlined")),
cl::desc("How sample profile inline replay treats sites that don't come "
"from the replay. Original: defers to original advisor, "
"AlwaysInline: inline all sites not in replay, NeverInline: "
"inline no sites not in replay"),
cl::Hidden);
static cl::opt<CallSiteFormat::Format> ProfileInlineReplayFormat(
"sample-profile-inline-replay-format",
cl::init(CallSiteFormat::Format::LineColumnDiscriminator),
cl::values(
clEnumValN(CallSiteFormat::Format::Line, "Line", "<Line Number>"),
clEnumValN(CallSiteFormat::Format::LineColumn, "LineColumn",
"<Line Number>:<Column Number>"),
clEnumValN(CallSiteFormat::Format::LineDiscriminator,
"LineDiscriminator", "<Line Number>.<Discriminator>"),
clEnumValN(CallSiteFormat::Format::LineColumnDiscriminator,
"LineColumnDiscriminator",
"<Line Number>:<Column Number>.<Discriminator> (default)")),
cl::desc("How sample profile inline replay file is formatted"), cl::Hidden);
static cl::opt<unsigned>
MaxNumPromotions("sample-profile-icp-max-prom", cl::init(3), cl::Hidden,
cl::desc("Max number of promotions for a single indirect "
"call callsite in sample profile loader"));
static cl::opt<bool> OverwriteExistingWeights(
"overwrite-existing-weights", cl::Hidden, cl::init(false),
cl::desc("Ignore existing branch weights on IR and always overwrite."));
static cl::opt<bool> AnnotateSampleProfileInlinePhase(
"annotate-sample-profile-inline-phase", cl::Hidden, cl::init(false),
cl::desc("Annotate LTO phase (prelink / postlink), or main (no LTO) for "
"sample-profile inline pass name."));
namespace llvm {
extern cl::opt<bool> EnableExtTspBlockPlacement;
}
namespace {
using BlockWeightMap = DenseMap<const BasicBlock *, uint64_t>;
using EquivalenceClassMap = DenseMap<const BasicBlock *, const BasicBlock *>;
using Edge = std::pair<const BasicBlock *, const BasicBlock *>;
using EdgeWeightMap = DenseMap<Edge, uint64_t>;
using BlockEdgeMap =
DenseMap<const BasicBlock *, SmallVector<const BasicBlock *, 8>>;
class GUIDToFuncNameMapper {
public:
GUIDToFuncNameMapper(Module &M, SampleProfileReader &Reader,
DenseMap<uint64_t, StringRef> &GUIDToFuncNameMap)
: CurrentReader(Reader), CurrentModule(M),
CurrentGUIDToFuncNameMap(GUIDToFuncNameMap) {
if (!CurrentReader.useMD5())
return;
for (const auto &F : CurrentModule) {
StringRef OrigName = F.getName();
CurrentGUIDToFuncNameMap.insert(
{Function::getGUID(OrigName), OrigName});
// Local to global var promotion used by optimization like thinlto
// will rename the var and add suffix like ".llvm.xxx" to the
// original local name. In sample profile, the suffixes of function
// names are all stripped. Since it is possible that the mapper is
// built in post-thin-link phase and var promotion has been done,
// we need to add the substring of function name without the suffix
// into the GUIDToFuncNameMap.
StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
if (CanonName != OrigName)
CurrentGUIDToFuncNameMap.insert(
{Function::getGUID(CanonName), CanonName});
}
// Update GUIDToFuncNameMap for each function including inlinees.
SetGUIDToFuncNameMapForAll(&CurrentGUIDToFuncNameMap);
}
~GUIDToFuncNameMapper() {
if (!CurrentReader.useMD5())
return;
CurrentGUIDToFuncNameMap.clear();
// Reset GUIDToFuncNameMap for of each function as they're no
// longer valid at this point.
SetGUIDToFuncNameMapForAll(nullptr);
}
private:
void SetGUIDToFuncNameMapForAll(DenseMap<uint64_t, StringRef> *Map) {
std::queue<FunctionSamples *> FSToUpdate;
for (auto &IFS : CurrentReader.getProfiles()) {
FSToUpdate.push(&IFS.second);
}
while (!FSToUpdate.empty()) {
FunctionSamples *FS = FSToUpdate.front();
FSToUpdate.pop();
FS->GUIDToFuncNameMap = Map;
for (const auto &ICS : FS->getCallsiteSamples()) {
const FunctionSamplesMap &FSMap = ICS.second;
for (const auto &IFS : FSMap) {
FunctionSamples &FS = const_cast<FunctionSamples &>(IFS.second);
FSToUpdate.push(&FS);
}
}
}
}
SampleProfileReader &CurrentReader;
Module &CurrentModule;
DenseMap<uint64_t, StringRef> &CurrentGUIDToFuncNameMap;
};
// Inline candidate used by iterative callsite prioritized inliner
struct InlineCandidate {
CallBase *CallInstr;
const FunctionSamples *CalleeSamples;
// Prorated callsite count, which will be used to guide inlining. For example,
// if a callsite is duplicated in LTO prelink, then in LTO postlink the two
// copies will get their own distribution factors and their prorated counts
// will be used to decide if they should be inlined independently.
uint64_t CallsiteCount;
// Call site distribution factor to prorate the profile samples for a
// duplicated callsite. Default value is 1.0.
float CallsiteDistribution;
};
// Inline candidate comparer using call site weight
struct CandidateComparer {
bool operator()(const InlineCandidate &LHS, const InlineCandidate &RHS) {
if (LHS.CallsiteCount != RHS.CallsiteCount)
return LHS.CallsiteCount < RHS.CallsiteCount;
const FunctionSamples *LCS = LHS.CalleeSamples;
const FunctionSamples *RCS = RHS.CalleeSamples;
assert(LCS && RCS && "Expect non-null FunctionSamples");
// Tie breaker using number of samples try to favor smaller functions first
if (LCS->getBodySamples().size() != RCS->getBodySamples().size())
return LCS->getBodySamples().size() > RCS->getBodySamples().size();
// Tie breaker using GUID so we have stable/deterministic inlining order
return LCS->getGUID() < RCS->getGUID();
}
};
using CandidateQueue =
PriorityQueue<InlineCandidate, std::vector<InlineCandidate>,
CandidateComparer>;
/// Sample profile pass.
///
/// This pass reads profile data from the file specified by
/// -sample-profile-file and annotates every affected function with the
/// profile information found in that file.
class SampleProfileLoader final : public SampleProfileLoaderBaseImpl<Function> {
public:
SampleProfileLoader(
StringRef Name, StringRef RemapName, ThinOrFullLTOPhase LTOPhase,
IntrusiveRefCntPtr<vfs::FileSystem> FS,
std::function<AssumptionCache &(Function &)> GetAssumptionCache,
std::function<TargetTransformInfo &(Function &)> GetTargetTransformInfo,
std::function<const TargetLibraryInfo &(Function &)> GetTLI)
: SampleProfileLoaderBaseImpl(std::string(Name), std::string(RemapName),
std::move(FS)),
GetAC(std::move(GetAssumptionCache)),
GetTTI(std::move(GetTargetTransformInfo)), GetTLI(std::move(GetTLI)),
LTOPhase(LTOPhase),
AnnotatedPassName(AnnotateSampleProfileInlinePhase
? llvm::AnnotateInlinePassName(InlineContext{
LTOPhase, InlinePass::SampleProfileInliner})
: CSINLINE_DEBUG) {}
bool doInitialization(Module &M, FunctionAnalysisManager *FAM = nullptr);
bool runOnModule(Module &M, ModuleAnalysisManager *AM,
ProfileSummaryInfo *_PSI, LazyCallGraph &CG);
protected:
bool runOnFunction(Function &F, ModuleAnalysisManager *AM);
bool emitAnnotations(Function &F);
ErrorOr<uint64_t> getInstWeight(const Instruction &I) override;
const FunctionSamples *findCalleeFunctionSamples(const CallBase &I) const;
const FunctionSamples *
findFunctionSamples(const Instruction &I) const override;
std::vector<const FunctionSamples *>
findIndirectCallFunctionSamples(const Instruction &I, uint64_t &Sum) const;
void findExternalInlineCandidate(CallBase *CB, const FunctionSamples *Samples,
DenseSet<GlobalValue::GUID> &InlinedGUIDs,
uint64_t Threshold);
// Attempt to promote indirect call and also inline the promoted call
bool tryPromoteAndInlineCandidate(
Function &F, InlineCandidate &Candidate, uint64_t SumOrigin,
uint64_t &Sum, SmallVector<CallBase *, 8> *InlinedCallSites = nullptr);
bool inlineHotFunctions(Function &F,
DenseSet<GlobalValue::GUID> &InlinedGUIDs);
std::optional<InlineCost> getExternalInlineAdvisorCost(CallBase &CB);
bool getExternalInlineAdvisorShouldInline(CallBase &CB);
InlineCost shouldInlineCandidate(InlineCandidate &Candidate);
bool getInlineCandidate(InlineCandidate *NewCandidate, CallBase *CB);
bool
tryInlineCandidate(InlineCandidate &Candidate,
SmallVector<CallBase *, 8> *InlinedCallSites = nullptr);
bool
inlineHotFunctionsWithPriority(Function &F,
DenseSet<GlobalValue::GUID> &InlinedGUIDs);
// Inline cold/small functions in addition to hot ones
bool shouldInlineColdCallee(CallBase &CallInst);
void emitOptimizationRemarksForInlineCandidates(
const SmallVectorImpl<CallBase *> &Candidates, const Function &F,
bool Hot);
void promoteMergeNotInlinedContextSamples(
MapVector<CallBase *, const FunctionSamples *> NonInlinedCallSites,
const Function &F);
std::vector<Function *> buildFunctionOrder(Module &M, LazyCallGraph &CG);
std::unique_ptr<ProfiledCallGraph> buildProfiledCallGraph(Module &M);
void generateMDProfMetadata(Function &F);
bool rejectHighStalenessProfile(Module &M, ProfileSummaryInfo *PSI,
const SampleProfileMap &Profiles);
void removePseudoProbeInsts(Module &M);
/// Map from function name to Function *. Used to find the function from
/// the function name. If the function name contains suffix, additional
/// entry is added to map from the stripped name to the function if there
/// is one-to-one mapping.
HashKeyMap<std::unordered_map, FunctionId, Function *> SymbolMap;
std::function<AssumptionCache &(Function &)> GetAC;
std::function<TargetTransformInfo &(Function &)> GetTTI;
std::function<const TargetLibraryInfo &(Function &)> GetTLI;
/// Profile tracker for different context.
std::unique_ptr<SampleContextTracker> ContextTracker;
/// Flag indicating which LTO/ThinLTO phase the pass is invoked in.
///
/// We need to know the LTO phase because for example in ThinLTOPrelink
/// phase, in annotation, we should not promote indirect calls. Instead,
/// we will mark GUIDs that needs to be annotated to the function.
const ThinOrFullLTOPhase LTOPhase;
const std::string AnnotatedPassName;
/// Profle Symbol list tells whether a function name appears in the binary
/// used to generate the current profile.
std::unique_ptr<ProfileSymbolList> PSL;
/// Total number of samples collected in this profile.
///
/// This is the sum of all the samples collected in all the functions executed
/// at runtime.
uint64_t TotalCollectedSamples = 0;
// Information recorded when we declined to inline a call site
// because we have determined it is too cold is accumulated for
// each callee function. Initially this is just the entry count.
struct NotInlinedProfileInfo {
uint64_t entryCount;
};
DenseMap<Function *, NotInlinedProfileInfo> notInlinedCallInfo;
// GUIDToFuncNameMap saves the mapping from GUID to the symbol name, for
// all the function symbols defined or declared in current module.
DenseMap<uint64_t, StringRef> GUIDToFuncNameMap;
// All the Names used in FunctionSamples including outline function
// names, inline instance names and call target names.
StringSet<> NamesInProfile;
// MD5 version of NamesInProfile. Either NamesInProfile or GUIDsInProfile is
// populated, depends on whether the profile uses MD5. Because the name table
// generally contains several magnitude more entries than the number of
// functions, we do not want to convert all names from one form to another.
llvm::DenseSet<uint64_t> GUIDsInProfile;
// For symbol in profile symbol list, whether to regard their profiles
// to be accurate. It is mainly decided by existance of profile symbol
// list and -profile-accurate-for-symsinlist flag, but it can be
// overriden by -profile-sample-accurate or profile-sample-accurate
// attribute.
bool ProfAccForSymsInList;
// External inline advisor used to replay inline decision from remarks.
std::unique_ptr<InlineAdvisor> ExternalInlineAdvisor;
// A helper to implement the sample profile matching algorithm.
std::unique_ptr<SampleProfileMatcher> MatchingManager;
private:
const char *getAnnotatedRemarkPassName() const {
return AnnotatedPassName.c_str();
}
};
} // end anonymous namespace
namespace llvm {
template <>
inline bool SampleProfileInference<Function>::isExit(const BasicBlock *BB) {
return succ_empty(BB);
}
template <>
inline void SampleProfileInference<Function>::findUnlikelyJumps(
const std::vector<const BasicBlockT *> &BasicBlocks,
BlockEdgeMap &Successors, FlowFunction &Func) {
for (auto &Jump : Func.Jumps) {
const auto *BB = BasicBlocks[Jump.Source];
const auto *Succ = BasicBlocks[Jump.Target];
const Instruction *TI = BB->getTerminator();
// Check if a block ends with InvokeInst and mark non-taken branch unlikely.
// In that case block Succ should be a landing pad
if (Successors[BB].size() == 2 && Successors[BB].back() == Succ) {
if (isa<InvokeInst>(TI)) {
Jump.IsUnlikely = true;
}
}
const Instruction *SuccTI = Succ->getTerminator();
// Check if the target block contains UnreachableInst and mark it unlikely
if (SuccTI->getNumSuccessors() == 0) {
if (isa<UnreachableInst>(SuccTI)) {
Jump.IsUnlikely = true;
}
}
}
}
template <>
void SampleProfileLoaderBaseImpl<Function>::computeDominanceAndLoopInfo(
Function &F) {
DT.reset(new DominatorTree);
DT->recalculate(F);
PDT.reset(new PostDominatorTree(F));
LI.reset(new LoopInfo);
LI->analyze(*DT);
}
} // namespace llvm
ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
if (FunctionSamples::ProfileIsProbeBased)
return getProbeWeight(Inst);
const DebugLoc &DLoc = Inst.getDebugLoc();
if (!DLoc)
return std::error_code();
// Ignore all intrinsics, phinodes and branch instructions.
// Branch and phinodes instruction usually contains debug info from sources
// outside of the residing basic block, thus we ignore them during annotation.
if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst) || isa<PHINode>(Inst))
return std::error_code();
// For non-CS profile, if a direct call/invoke instruction is inlined in
// profile (findCalleeFunctionSamples returns non-empty result), but not
// inlined here, it means that the inlined callsite has no sample, thus the
// call instruction should have 0 count.
// For CS profile, the callsite count of previously inlined callees is
// populated with the entry count of the callees.
if (!FunctionSamples::ProfileIsCS)
if (const auto *CB = dyn_cast<CallBase>(&Inst))
if (!CB->isIndirectCall() && findCalleeFunctionSamples(*CB))
return 0;
return getInstWeightImpl(Inst);
}
/// Get the FunctionSamples for a call instruction.
///
/// The FunctionSamples of a call/invoke instruction \p Inst is the inlined
/// instance in which that call instruction is calling to. It contains
/// all samples that resides in the inlined instance. We first find the
/// inlined instance in which the call instruction is from, then we
/// traverse its children to find the callsite with the matching
/// location.
///
/// \param Inst Call/Invoke instruction to query.
///
/// \returns The FunctionSamples pointer to the inlined instance.
const FunctionSamples *
SampleProfileLoader::findCalleeFunctionSamples(const CallBase &Inst) const {
const DILocation *DIL = Inst.getDebugLoc();
if (!DIL) {
return nullptr;
}
StringRef CalleeName;
if (Function *Callee = Inst.getCalledFunction())
CalleeName = Callee->getName();
if (FunctionSamples::ProfileIsCS)
return ContextTracker->getCalleeContextSamplesFor(Inst, CalleeName);
const FunctionSamples *FS = findFunctionSamples(Inst);
if (FS == nullptr)
return nullptr;
return FS->findFunctionSamplesAt(FunctionSamples::getCallSiteIdentifier(DIL),
CalleeName, Reader->getRemapper());
}
/// Returns a vector of FunctionSamples that are the indirect call targets
/// of \p Inst. The vector is sorted by the total number of samples. Stores
/// the total call count of the indirect call in \p Sum.
std::vector<const FunctionSamples *>
SampleProfileLoader::findIndirectCallFunctionSamples(
const Instruction &Inst, uint64_t &Sum) const {
const DILocation *DIL = Inst.getDebugLoc();
std::vector<const FunctionSamples *> R;
if (!DIL) {
return R;
}
auto FSCompare = [](const FunctionSamples *L, const FunctionSamples *R) {
assert(L && R && "Expect non-null FunctionSamples");
if (L->getHeadSamplesEstimate() != R->getHeadSamplesEstimate())
return L->getHeadSamplesEstimate() > R->getHeadSamplesEstimate();
return L->getGUID() < R->getGUID();
};
if (FunctionSamples::ProfileIsCS) {
auto CalleeSamples =
ContextTracker->getIndirectCalleeContextSamplesFor(DIL);
if (CalleeSamples.empty())
return R;
// For CSSPGO, we only use target context profile's entry count
// as that already includes both inlined callee and non-inlined ones..
Sum = 0;
for (const auto *const FS : CalleeSamples) {
Sum += FS->getHeadSamplesEstimate();
R.push_back(FS);
}
llvm::sort(R, FSCompare);
return R;
}
const FunctionSamples *FS = findFunctionSamples(Inst);
if (FS == nullptr)
return R;
auto CallSite = FunctionSamples::getCallSiteIdentifier(DIL);
Sum = 0;
if (auto T = FS->findCallTargetMapAt(CallSite))
for (const auto &T_C : *T)
Sum += T_C.second;
if (const FunctionSamplesMap *M = FS->findFunctionSamplesMapAt(CallSite)) {
if (M->empty())
return R;
for (const auto &NameFS : *M) {
Sum += NameFS.second.getHeadSamplesEstimate();
R.push_back(&NameFS.second);
}
llvm::sort(R, FSCompare);
}
return R;
}
const FunctionSamples *
SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
if (FunctionSamples::ProfileIsProbeBased) {
std::optional<PseudoProbe> Probe = extractProbe(Inst);
if (!Probe)
return nullptr;
}
const DILocation *DIL = Inst.getDebugLoc();
if (!DIL)
return Samples;
auto it = DILocation2SampleMap.try_emplace(DIL,nullptr);
if (it.second) {
if (FunctionSamples::ProfileIsCS)
it.first->second = ContextTracker->getContextSamplesFor(DIL);
else
it.first->second =
Samples->findFunctionSamples(DIL, Reader->getRemapper());
}
return it.first->second;
}
/// Check whether the indirect call promotion history of \p Inst allows
/// the promotion for \p Candidate.
/// If the profile count for the promotion candidate \p Candidate is
/// NOMORE_ICP_MAGICNUM, it means \p Candidate has already been promoted
/// for \p Inst. If we already have at least MaxNumPromotions
/// NOMORE_ICP_MAGICNUM count values in the value profile of \p Inst, we
/// cannot promote for \p Inst anymore.
static bool doesHistoryAllowICP(const Instruction &Inst, StringRef Candidate) {
uint32_t NumVals = 0;
uint64_t TotalCount = 0;
std::unique_ptr<InstrProfValueData[]> ValueData =
std::make_unique<InstrProfValueData[]>(MaxNumPromotions);
bool Valid =
getValueProfDataFromInst(Inst, IPVK_IndirectCallTarget, MaxNumPromotions,
ValueData.get(), NumVals, TotalCount, true);
// No valid value profile so no promoted targets have been recorded
// before. Ok to do ICP.
if (!Valid)
return true;
unsigned NumPromoted = 0;
for (uint32_t I = 0; I < NumVals; I++) {
if (ValueData[I].Count != NOMORE_ICP_MAGICNUM)
continue;
// If the promotion candidate has NOMORE_ICP_MAGICNUM count in the
// metadata, it means the candidate has been promoted for this
// indirect call.
if (ValueData[I].Value == Function::getGUID(Candidate))
return false;
NumPromoted++;
// If already have MaxNumPromotions promotion, don't do it anymore.
if (NumPromoted == MaxNumPromotions)
return false;
}
return true;
}
/// Update indirect call target profile metadata for \p Inst.
/// Usually \p Sum is the sum of counts of all the targets for \p Inst.
/// If it is 0, it means updateIDTMetaData is used to mark a
/// certain target to be promoted already. If it is not zero,
/// we expect to use it to update the total count in the value profile.
static void
updateIDTMetaData(Instruction &Inst,
const SmallVectorImpl<InstrProfValueData> &CallTargets,
uint64_t Sum) {
// Bail out early if MaxNumPromotions is zero.
// This prevents allocating an array of zero length below.
//
// Note `updateIDTMetaData` is called in two places so check
// `MaxNumPromotions` inside it.
if (MaxNumPromotions == 0)
return;
uint32_t NumVals = 0;
// OldSum is the existing total count in the value profile data.
uint64_t OldSum = 0;
std::unique_ptr<InstrProfValueData[]> ValueData =
std::make_unique<InstrProfValueData[]>(MaxNumPromotions);
bool Valid =
getValueProfDataFromInst(Inst, IPVK_IndirectCallTarget, MaxNumPromotions,
ValueData.get(), NumVals, OldSum, true);
DenseMap<uint64_t, uint64_t> ValueCountMap;
if (Sum == 0) {
assert((CallTargets.size() == 1 &&
CallTargets[0].Count == NOMORE_ICP_MAGICNUM) &&
"If sum is 0, assume only one element in CallTargets "
"with count being NOMORE_ICP_MAGICNUM");
// Initialize ValueCountMap with existing value profile data.
if (Valid) {
for (uint32_t I = 0; I < NumVals; I++)
ValueCountMap[ValueData[I].Value] = ValueData[I].Count;
}
auto Pair =
ValueCountMap.try_emplace(CallTargets[0].Value, CallTargets[0].Count);
// If the target already exists in value profile, decrease the total
// count OldSum and reset the target's count to NOMORE_ICP_MAGICNUM.
if (!Pair.second) {
OldSum -= Pair.first->second;
Pair.first->second = NOMORE_ICP_MAGICNUM;
}
Sum = OldSum;
} else {
// Initialize ValueCountMap with existing NOMORE_ICP_MAGICNUM
// counts in the value profile.
if (Valid) {
for (uint32_t I = 0; I < NumVals; I++) {
if (ValueData[I].Count == NOMORE_ICP_MAGICNUM)
ValueCountMap[ValueData[I].Value] = ValueData[I].Count;
}
}
for (const auto &Data : CallTargets) {
auto Pair = ValueCountMap.try_emplace(Data.Value, Data.Count);
if (Pair.second)
continue;
// The target represented by Data.Value has already been promoted.
// Keep the count as NOMORE_ICP_MAGICNUM in the profile and decrease
// Sum by Data.Count.
assert(Sum >= Data.Count && "Sum should never be less than Data.Count");
Sum -= Data.Count;
}
}
SmallVector<InstrProfValueData, 8> NewCallTargets;
for (const auto &ValueCount : ValueCountMap) {
NewCallTargets.emplace_back(
InstrProfValueData{ValueCount.first, ValueCount.second});
}
llvm::sort(NewCallTargets,
[](const InstrProfValueData &L, const InstrProfValueData &R) {
if (L.Count != R.Count)
return L.Count > R.Count;
return L.Value > R.Value;
});
uint32_t MaxMDCount =
std::min(NewCallTargets.size(), static_cast<size_t>(MaxNumPromotions));
annotateValueSite(*Inst.getParent()->getParent()->getParent(), Inst,
NewCallTargets, Sum, IPVK_IndirectCallTarget, MaxMDCount);
}
/// Attempt to promote indirect call and also inline the promoted call.
///
/// \param F Caller function.
/// \param Candidate ICP and inline candidate.
/// \param SumOrigin Original sum of target counts for indirect call before
/// promoting given candidate.
/// \param Sum Prorated sum of remaining target counts for indirect call
/// after promoting given candidate.
/// \param InlinedCallSite Output vector for new call sites exposed after
/// inlining.
bool SampleProfileLoader::tryPromoteAndInlineCandidate(
Function &F, InlineCandidate &Candidate, uint64_t SumOrigin, uint64_t &Sum,
SmallVector<CallBase *, 8> *InlinedCallSite) {
// Bail out early if sample-loader inliner is disabled.
if (DisableSampleLoaderInlining)
return false;
// Bail out early if MaxNumPromotions is zero.
// This prevents allocating an array of zero length in callees below.
if (MaxNumPromotions == 0)
return false;
auto CalleeFunctionName = Candidate.CalleeSamples->getFunction();
auto R = SymbolMap.find(CalleeFunctionName);
if (R == SymbolMap.end() || !R->second)
return false;
auto &CI = *Candidate.CallInstr;
if (!doesHistoryAllowICP(CI, R->second->getName()))
return false;
const char *Reason = "Callee function not available";
// R->getValue() != &F is to prevent promoting a recursive call.
// If it is a recursive call, we do not inline it as it could bloat
// the code exponentially. There is way to better handle this, e.g.
// clone the caller first, and inline the cloned caller if it is
// recursive. As llvm does not inline recursive calls, we will
// simply ignore it instead of handling it explicitly.
if (!R->second->isDeclaration() && R->second->getSubprogram() &&
R->second->hasFnAttribute("use-sample-profile") &&
R->second != &F && isLegalToPromote(CI, R->second, &Reason)) {
// For promoted target, set its value with NOMORE_ICP_MAGICNUM count
// in the value profile metadata so the target won't be promoted again.
SmallVector<InstrProfValueData, 1> SortedCallTargets = {InstrProfValueData{
Function::getGUID(R->second->getName()), NOMORE_ICP_MAGICNUM}};
updateIDTMetaData(CI, SortedCallTargets, 0);
auto *DI = &pgo::promoteIndirectCall(
CI, R->second, Candidate.CallsiteCount, Sum, false, ORE);
if (DI) {
Sum -= Candidate.CallsiteCount;
// Do not prorate the indirect callsite distribution since the original
// distribution will be used to scale down non-promoted profile target
// counts later. By doing this we lose track of the real callsite count
// for the leftover indirect callsite as a trade off for accurate call
// target counts.
// TODO: Ideally we would have two separate factors, one for call site
// counts and one is used to prorate call target counts.
// Do not update the promoted direct callsite distribution at this
// point since the original distribution combined with the callee profile
// will be used to prorate callsites from the callee if inlined. Once not
// inlined, the direct callsite distribution should be prorated so that
// the it will reflect the real callsite counts.
Candidate.CallInstr = DI;
if (isa<CallInst>(DI) || isa<InvokeInst>(DI)) {
bool Inlined = tryInlineCandidate(Candidate, InlinedCallSite);
if (!Inlined) {
// Prorate the direct callsite distribution so that it reflects real
// callsite counts.
setProbeDistributionFactor(
*DI, static_cast<float>(Candidate.CallsiteCount) / SumOrigin);
}
return Inlined;
}
}
} else {
LLVM_DEBUG(dbgs() << "\nFailed to promote indirect call to "
<< FunctionSamples::getCanonicalFnName(
Candidate.CallInstr->getName())<< " because "
<< Reason << "\n");
}
return false;
}
bool SampleProfileLoader::shouldInlineColdCallee(CallBase &CallInst) {
if (!ProfileSizeInline)
return false;
Function *Callee = CallInst.getCalledFunction();
if (Callee == nullptr)
return false;
InlineCost Cost = getInlineCost(CallInst, getInlineParams(), GetTTI(*Callee),
GetAC, GetTLI);
if (Cost.isNever())
return false;
if (Cost.isAlways())
return true;
return Cost.getCost() <= SampleColdCallSiteThreshold;
}
void SampleProfileLoader::emitOptimizationRemarksForInlineCandidates(
const SmallVectorImpl<CallBase *> &Candidates, const Function &F,
bool Hot) {
for (auto *I : Candidates) {
Function *CalledFunction = I->getCalledFunction();
if (CalledFunction) {
ORE->emit(OptimizationRemarkAnalysis(getAnnotatedRemarkPassName(),
"InlineAttempt", I->getDebugLoc(),
I->getParent())
<< "previous inlining reattempted for "
<< (Hot ? "hotness: '" : "size: '")
<< ore::NV("Callee", CalledFunction) << "' into '"
<< ore::NV("Caller", &F) << "'");
}
}
}
void SampleProfileLoader::findExternalInlineCandidate(
CallBase *CB, const FunctionSamples *Samples,
DenseSet<GlobalValue::GUID> &InlinedGUIDs, uint64_t Threshold) {
// If ExternalInlineAdvisor(ReplayInlineAdvisor) wants to inline an external
// function make sure it's imported
if (CB && getExternalInlineAdvisorShouldInline(*CB)) {
// Samples may not exist for replayed function, if so
// just add the direct GUID and move on
if (!Samples) {
InlinedGUIDs.insert(
Function::getGUID(CB->getCalledFunction()->getName()));
return;
}
// Otherwise, drop the threshold to import everything that we can
Threshold = 0;
}
// In some rare cases, call instruction could be changed after being pushed
// into inline candidate queue, this is because earlier inlining may expose
// constant propagation which can change indirect call to direct call. When
// this happens, we may fail to find matching function samples for the
// candidate later, even if a match was found when the candidate was enqueued.
if (!Samples)
return;
// For AutoFDO profile, retrieve candidate profiles by walking over
// the nested inlinee profiles.
if (!FunctionSamples::ProfileIsCS) {
// Set threshold to zero to honor pre-inliner decision.
if (UsePreInlinerDecision)
Threshold = 0;
Samples->findInlinedFunctions(InlinedGUIDs, SymbolMap, Threshold);
return;
}
ContextTrieNode *Caller = ContextTracker->getContextNodeForProfile(Samples);
std::queue<ContextTrieNode *> CalleeList;
CalleeList.push(Caller);
while (!CalleeList.empty()) {
ContextTrieNode *Node = CalleeList.front();
CalleeList.pop();
FunctionSamples *CalleeSample = Node->getFunctionSamples();
// For CSSPGO profile, retrieve candidate profile by walking over the
// trie built for context profile. Note that also take call targets
// even if callee doesn't have a corresponding context profile.
if (!CalleeSample)
continue;
// If pre-inliner decision is used, honor that for importing as well.
bool PreInline =
UsePreInlinerDecision &&
CalleeSample->getContext().hasAttribute(ContextShouldBeInlined);
if (!PreInline && CalleeSample->getHeadSamplesEstimate() < Threshold)
continue;
Function *Func = SymbolMap.lookup(CalleeSample->getFunction());
// Add to the import list only when it's defined out of module.
if (!Func || Func->isDeclaration())
InlinedGUIDs.insert(CalleeSample->getGUID());
// Import hot CallTargets, which may not be available in IR because full
// profile annotation cannot be done until backend compilation in ThinLTO.
for (const auto &BS : CalleeSample->getBodySamples())
for (const auto &TS : BS.second.getCallTargets())
if (TS.second > Threshold) {
const Function *Callee = SymbolMap.lookup(TS.first);
if (!Callee || Callee->isDeclaration())
InlinedGUIDs.insert(TS.first.getHashCode());
}
// Import hot child context profile associted with callees. Note that this
// may have some overlap with the call target loop above, but doing this
// based child context profile again effectively allow us to use the max of
// entry count and call target count to determine importing.
for (auto &Child : Node->getAllChildContext()) {
ContextTrieNode *CalleeNode = &Child.second;
CalleeList.push(CalleeNode);
}
}
}
/// Iteratively inline hot callsites of a function.
///
/// Iteratively traverse all callsites of the function \p F, so as to
/// find out callsites with corresponding inline instances.
///
/// For such callsites,
/// - If it is hot enough, inline the callsites and adds callsites of the callee
/// into the caller. If the call is an indirect call, first promote
/// it to direct call. Each indirect call is limited with a single target.
///
/// - If a callsite is not inlined, merge the its profile to the outline
/// version (if --sample-profile-merge-inlinee is true), or scale the
/// counters of standalone function based on the profile of inlined
/// instances (if --sample-profile-merge-inlinee is false).
///
/// Later passes may consume the updated profiles.
///
/// \param F function to perform iterative inlining.
/// \param InlinedGUIDs a set to be updated to include all GUIDs that are
/// inlined in the profiled binary.
///
/// \returns True if there is any inline happened.
bool SampleProfileLoader::inlineHotFunctions(
Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
// ProfAccForSymsInList is used in callsiteIsHot. The assertion makes sure
// Profile symbol list is ignored when profile-sample-accurate is on.
assert((!ProfAccForSymsInList ||
(!ProfileSampleAccurate &&
!F.hasFnAttribute("profile-sample-accurate"))) &&
"ProfAccForSymsInList should be false when profile-sample-accurate "
"is enabled");
MapVector<CallBase *, const FunctionSamples *> LocalNotInlinedCallSites;
bool Changed = false;
bool LocalChanged = true;
while (LocalChanged) {
LocalChanged = false;
SmallVector<CallBase *, 10> CIS;
for (auto &BB : F) {
bool Hot = false;
SmallVector<CallBase *, 10> AllCandidates;
SmallVector<CallBase *, 10> ColdCandidates;
for (auto &I : BB) {
const FunctionSamples *FS = nullptr;
if (auto *CB = dyn_cast<CallBase>(&I)) {
if (!isa<IntrinsicInst>(I)) {
if ((FS = findCalleeFunctionSamples(*CB))) {
assert((!FunctionSamples::UseMD5 || FS->GUIDToFuncNameMap) &&
"GUIDToFuncNameMap has to be populated");
AllCandidates.push_back(CB);
if (FS->getHeadSamplesEstimate() > 0 ||
FunctionSamples::ProfileIsCS)
LocalNotInlinedCallSites.insert({CB, FS});
if (callsiteIsHot(FS, PSI, ProfAccForSymsInList))
Hot = true;
else if (shouldInlineColdCallee(*CB))
ColdCandidates.push_back(CB);
} else if (getExternalInlineAdvisorShouldInline(*CB)) {
AllCandidates.push_back(CB);
}
}
}
}
if (Hot || ExternalInlineAdvisor) {
CIS.insert(CIS.begin(), AllCandidates.begin(), AllCandidates.end());
emitOptimizationRemarksForInlineCandidates(AllCandidates, F, true);
} else {
CIS.insert(CIS.begin(), ColdCandidates.begin(), ColdCandidates.end());
emitOptimizationRemarksForInlineCandidates(ColdCandidates, F, false);
}
}
for (CallBase *I : CIS) {
Function *CalledFunction = I->getCalledFunction();
InlineCandidate Candidate = {I, LocalNotInlinedCallSites.lookup(I),
0 /* dummy count */,
1.0 /* dummy distribution factor */};
// Do not inline recursive calls.
if (CalledFunction == &F)
continue;
if (I->isIndirectCall()) {
uint64_t Sum;
for (const auto *FS : findIndirectCallFunctionSamples(*I, Sum)) {
uint64_t SumOrigin = Sum;
if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
findExternalInlineCandidate(I, FS, InlinedGUIDs,
PSI->getOrCompHotCountThreshold());
continue;
}
if (!callsiteIsHot(FS, PSI, ProfAccForSymsInList))
continue;
Candidate = {I, FS, FS->getHeadSamplesEstimate(), 1.0};
if (tryPromoteAndInlineCandidate(F, Candidate, SumOrigin, Sum)) {
LocalNotInlinedCallSites.erase(I);
LocalChanged = true;
}
}
} else if (CalledFunction && CalledFunction->getSubprogram() &&
!CalledFunction->isDeclaration()) {
if (tryInlineCandidate(Candidate)) {
LocalNotInlinedCallSites.erase(I);
LocalChanged = true;
}
} else if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
findExternalInlineCandidate(I, findCalleeFunctionSamples(*I),
InlinedGUIDs,
PSI->getOrCompHotCountThreshold());
}
}
Changed |= LocalChanged;
}
// For CS profile, profile for not inlined context will be merged when
// base profile is being retrieved.
if (!FunctionSamples::ProfileIsCS)
promoteMergeNotInlinedContextSamples(LocalNotInlinedCallSites, F);
return Changed;
}
bool SampleProfileLoader::tryInlineCandidate(
InlineCandidate &Candidate, SmallVector<CallBase *, 8> *InlinedCallSites) {
// Do not attempt to inline a candidate if
// --disable-sample-loader-inlining is true.
if (DisableSampleLoaderInlining)
return false;
CallBase &CB = *Candidate.CallInstr;
Function *CalledFunction = CB.getCalledFunction();
assert(CalledFunction && "Expect a callee with definition");
DebugLoc DLoc = CB.getDebugLoc();
BasicBlock *BB = CB.getParent();
InlineCost Cost = shouldInlineCandidate(Candidate);
if (Cost.isNever()) {
ORE->emit(OptimizationRemarkAnalysis(getAnnotatedRemarkPassName(),
"InlineFail", DLoc, BB)
<< "incompatible inlining");
return false;
}
if (!Cost)
return false;
InlineFunctionInfo IFI(GetAC);
IFI.UpdateProfile = false;
InlineResult IR = InlineFunction(CB, IFI,
/*MergeAttributes=*/true);
if (!IR.isSuccess())
return false;
// The call to InlineFunction erases I, so we can't pass it here.
emitInlinedIntoBasedOnCost(*ORE, DLoc, BB, *CalledFunction, *BB->getParent(),
Cost, true, getAnnotatedRemarkPassName());
// Now populate the list of newly exposed call sites.
if (InlinedCallSites) {
InlinedCallSites->clear();
for (auto &I : IFI.InlinedCallSites)
InlinedCallSites->push_back(I);
}
if (FunctionSamples::ProfileIsCS)
ContextTracker->markContextSamplesInlined(Candidate.CalleeSamples);
++NumCSInlined;
// Prorate inlined probes for a duplicated inlining callsite which probably
// has a distribution less than 100%. Samples for an inlinee should be
// distributed among the copies of the original callsite based on each
// callsite's distribution factor for counts accuracy. Note that an inlined
// probe may come with its own distribution factor if it has been duplicated
// in the inlinee body. The two factor are multiplied to reflect the
// aggregation of duplication.
if (Candidate.CallsiteDistribution < 1) {
for (auto &I : IFI.InlinedCallSites) {
if (std::optional<PseudoProbe> Probe = extractProbe(*I))
setProbeDistributionFactor(*I, Probe->Factor *
Candidate.CallsiteDistribution);
}
NumDuplicatedInlinesite++;
}
return true;
}
bool SampleProfileLoader::getInlineCandidate(InlineCandidate *NewCandidate,
CallBase *CB) {
assert(CB && "Expect non-null call instruction");
if (isa<IntrinsicInst>(CB))
return false;
// Find the callee's profile. For indirect call, find hottest target profile.
const FunctionSamples *CalleeSamples = findCalleeFunctionSamples(*CB);
// If ExternalInlineAdvisor wants to inline this site, do so even
// if Samples are not present.
if (!CalleeSamples && !getExternalInlineAdvisorShouldInline(*CB))
return false;
float Factor = 1.0;
if (std::optional<PseudoProbe> Probe = extractProbe(*CB))
Factor = Probe->Factor;
uint64_t CallsiteCount =
CalleeSamples ? CalleeSamples->getHeadSamplesEstimate() * Factor : 0;
*NewCandidate = {CB, CalleeSamples, CallsiteCount, Factor};
return true;
}
std::optional<InlineCost>
SampleProfileLoader::getExternalInlineAdvisorCost(CallBase &CB) {
std::unique_ptr<InlineAdvice> Advice = nullptr;
if (ExternalInlineAdvisor) {
Advice = ExternalInlineAdvisor->getAdvice(CB);
if (Advice) {
if (!Advice->isInliningRecommended()) {
Advice->recordUnattemptedInlining();
return InlineCost::getNever("not previously inlined");
}
Advice->recordInlining();
return InlineCost::getAlways("previously inlined");
}
}
return {};
}
bool SampleProfileLoader::getExternalInlineAdvisorShouldInline(CallBase &CB) {
std::optional<InlineCost> Cost = getExternalInlineAdvisorCost(CB);
return Cost ? !!*Cost : false;
}
InlineCost
SampleProfileLoader::shouldInlineCandidate(InlineCandidate &Candidate) {
if (std::optional<InlineCost> ReplayCost =
getExternalInlineAdvisorCost(*Candidate.CallInstr))
return *ReplayCost;
// Adjust threshold based on call site hotness, only do this for callsite
// prioritized inliner because otherwise cost-benefit check is done earlier.
int SampleThreshold = SampleColdCallSiteThreshold;
if (CallsitePrioritizedInline) {
if (Candidate.CallsiteCount > PSI->getHotCountThreshold())
SampleThreshold = SampleHotCallSiteThreshold;
else if (!ProfileSizeInline)
return InlineCost::getNever("cold callsite");
}
Function *Callee = Candidate.CallInstr->getCalledFunction();
assert(Callee && "Expect a definition for inline candidate of direct call");
InlineParams Params = getInlineParams();
// We will ignore the threshold from inline cost, so always get full cost.
Params.ComputeFullInlineCost = true;
Params.AllowRecursiveCall = AllowRecursiveInline;
// Checks if there is anything in the reachable portion of the callee at
// this callsite that makes this inlining potentially illegal. Need to
// set ComputeFullInlineCost, otherwise getInlineCost may return early
// when cost exceeds threshold without checking all IRs in the callee.
// The acutal cost does not matter because we only checks isNever() to
// see if it is legal to inline the callsite.
InlineCost Cost = getInlineCost(*Candidate.CallInstr, Callee, Params,
GetTTI(*Callee), GetAC, GetTLI);
// Honor always inline and never inline from call analyzer
if (Cost.isNever() || Cost.isAlways())
return Cost;
// With CSSPGO, the preinliner in llvm-profgen can estimate global inline
// decisions based on hotness as well as accurate function byte sizes for
// given context using function/inlinee sizes from previous build. It
// stores the decision in profile, and also adjust/merge context profile
// aiming at better context-sensitive post-inline profile quality, assuming
// all inline decision estimates are going to be honored by compiler. Here
// we replay that inline decision under `sample-profile-use-preinliner`.
// Note that we don't need to handle negative decision from preinliner as
// context profile for not inlined calls are merged by preinliner already.
if (UsePreInlinerDecision && Candidate.CalleeSamples) {
// Once two node are merged due to promotion, we're losing some context
// so the original context-sensitive preinliner decision should be ignored
// for SyntheticContext.
SampleContext &Context = Candidate.CalleeSamples->getContext();
if (!Context.hasState(SyntheticContext) &&
Context.hasAttribute(ContextShouldBeInlined))
return InlineCost::getAlways("preinliner");
}
// For old FDO inliner, we inline the call site as long as cost is not
// "Never". The cost-benefit check is done earlier.
if (!CallsitePrioritizedInline) {
return InlineCost::get(Cost.getCost(), INT_MAX);
}
// Otherwise only use the cost from call analyzer, but overwite threshold with
// Sample PGO threshold.
return InlineCost::get(Cost.getCost(), SampleThreshold);
}
bool SampleProfileLoader::inlineHotFunctionsWithPriority(
Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
// ProfAccForSymsInList is used in callsiteIsHot. The assertion makes sure
// Profile symbol list is ignored when profile-sample-accurate is on.
assert((!ProfAccForSymsInList ||
(!ProfileSampleAccurate &&
!F.hasFnAttribute("profile-sample-accurate"))) &&
"ProfAccForSymsInList should be false when profile-sample-accurate "
"is enabled");
// Populating worklist with initial call sites from root inliner, along
// with call site weights.
CandidateQueue CQueue;
InlineCandidate NewCandidate;
for (auto &BB : F) {
for (auto &I : BB) {
auto *CB = dyn_cast<CallBase>(&I);
if (!CB)
continue;
if (getInlineCandidate(&NewCandidate, CB))
CQueue.push(NewCandidate);
}
}
// Cap the size growth from profile guided inlining. This is needed even
// though cost of each inline candidate already accounts for callee size,
// because with top-down inlining, we can grow inliner size significantly
// with large number of smaller inlinees each pass the cost check.
assert(ProfileInlineLimitMax >= ProfileInlineLimitMin &&
"Max inline size limit should not be smaller than min inline size "
"limit.");
unsigned SizeLimit = F.getInstructionCount() * ProfileInlineGrowthLimit;
SizeLimit = std::min(SizeLimit, (unsigned)ProfileInlineLimitMax);
SizeLimit = std::max(SizeLimit, (unsigned)ProfileInlineLimitMin);
if (ExternalInlineAdvisor)
SizeLimit = std::numeric_limits<unsigned>::max();
MapVector<CallBase *, const FunctionSamples *> LocalNotInlinedCallSites;
// Perform iterative BFS call site prioritized inlining
bool Changed = false;
while (!CQueue.empty() && F.getInstructionCount() < SizeLimit) {
InlineCandidate Candidate = CQueue.top();
CQueue.pop();
CallBase *I = Candidate.CallInstr;
Function *CalledFunction = I->getCalledFunction();
if (CalledFunction == &F)
continue;
if (I->isIndirectCall()) {
uint64_t Sum = 0;
auto CalleeSamples = findIndirectCallFunctionSamples(*I, Sum);
uint64_t SumOrigin = Sum;
Sum *= Candidate.CallsiteDistribution;
unsigned ICPCount = 0;
for (const auto *FS : CalleeSamples) {
// TODO: Consider disable pre-lTO ICP for MonoLTO as well
if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
findExternalInlineCandidate(I, FS, InlinedGUIDs,
PSI->getOrCompHotCountThreshold());
continue;
}
uint64_t EntryCountDistributed =
FS->getHeadSamplesEstimate() * Candidate.CallsiteDistribution;
// In addition to regular inline cost check, we also need to make sure
// ICP isn't introducing excessive speculative checks even if individual
// target looks beneficial to promote and inline. That means we should
// only do ICP when there's a small number dominant targets.
if (ICPCount >= ProfileICPRelativeHotnessSkip &&
EntryCountDistributed * 100 < SumOrigin * ProfileICPRelativeHotness)
break;
// TODO: Fix CallAnalyzer to handle all indirect calls.
// For indirect call, we don't run CallAnalyzer to get InlineCost
// before actual inlining. This is because we could see two different
// types from the same definition, which makes CallAnalyzer choke as
// it's expecting matching parameter type on both caller and callee
// side. See example from PR18962 for the triggering cases (the bug was
// fixed, but we generate different types).
if (!PSI->isHotCount(EntryCountDistributed))
break;
SmallVector<CallBase *, 8> InlinedCallSites;
// Attach function profile for promoted indirect callee, and update
// call site count for the promoted inline candidate too.
Candidate = {I, FS, EntryCountDistributed,
Candidate.CallsiteDistribution};
if (tryPromoteAndInlineCandidate(F, Candidate, SumOrigin, Sum,
&InlinedCallSites)) {
for (auto *CB : InlinedCallSites) {
if (getInlineCandidate(&NewCandidate, CB))
CQueue.emplace(NewCandidate);
}
ICPCount++;
Changed = true;
} else if (!ContextTracker) {
LocalNotInlinedCallSites.insert({I, FS});
}
}
} else if (CalledFunction && CalledFunction->getSubprogram() &&
!CalledFunction->isDeclaration()) {
SmallVector<CallBase *, 8> InlinedCallSites;
if (tryInlineCandidate(Candidate, &InlinedCallSites)) {
for (auto *CB : InlinedCallSites) {
if (getInlineCandidate(&NewCandidate, CB))
CQueue.emplace(NewCandidate);
}
Changed = true;
} else if (!ContextTracker) {
LocalNotInlinedCallSites.insert({I, Candidate.CalleeSamples});
}
} else if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
findExternalInlineCandidate(I, findCalleeFunctionSamples(*I),
InlinedGUIDs,
PSI->getOrCompHotCountThreshold());
}
}
if (!CQueue.empty()) {
if (SizeLimit == (unsigned)ProfileInlineLimitMax)
++NumCSInlinedHitMaxLimit;
else if (SizeLimit == (unsigned)ProfileInlineLimitMin)
++NumCSInlinedHitMinLimit;
else
++NumCSInlinedHitGrowthLimit;
}
// For CS profile, profile for not inlined context will be merged when
// base profile is being retrieved.
if (!FunctionSamples::ProfileIsCS)
promoteMergeNotInlinedContextSamples(LocalNotInlinedCallSites, F);
return Changed;
}
void SampleProfileLoader::promoteMergeNotInlinedContextSamples(
MapVector<CallBase *, const FunctionSamples *> NonInlinedCallSites,
const Function &F) {
// Accumulate not inlined callsite information into notInlinedSamples
for (const auto &Pair : NonInlinedCallSites) {
CallBase *I = Pair.first;
Function *Callee = I->getCalledFunction();
if (!Callee || Callee->isDeclaration())
continue;
ORE->emit(
OptimizationRemarkAnalysis(getAnnotatedRemarkPassName(), "NotInline",
I->getDebugLoc(), I->getParent())
<< "previous inlining not repeated: '" << ore::NV("Callee", Callee)
<< "' into '" << ore::NV("Caller", &F) << "'");
++NumCSNotInlined;
const FunctionSamples *FS = Pair.second;
if (FS->getTotalSamples() == 0 && FS->getHeadSamplesEstimate() == 0) {
continue;
}
// Do not merge a context that is already duplicated into the base profile.
if (FS->getContext().hasAttribute(sampleprof::ContextDuplicatedIntoBase))
continue;
if (ProfileMergeInlinee) {
// A function call can be replicated by optimizations like callsite
// splitting or jump threading and the replicates end up sharing the
// sample nested callee profile instead of slicing the original
// inlinee's profile. We want to do merge exactly once by filtering out
// callee profiles with a non-zero head sample count.
if (FS->getHeadSamples() == 0) {
// Use entry samples as head samples during the merge, as inlinees
// don't have head samples.
const_cast<FunctionSamples *>(FS)->addHeadSamples(
FS->getHeadSamplesEstimate());
// Note that we have to do the merge right after processing function.
// This allows OutlineFS's profile to be used for annotation during
// top-down processing of functions' annotation.
FunctionSamples *OutlineFS = Reader->getSamplesFor(*Callee);
// If outlined function does not exist in the profile, add it to a
// separate map so that it does not rehash the original profile.
if (!OutlineFS)
OutlineFS = &OutlineFunctionSamples[
FunctionId(FunctionSamples::getCanonicalFnName(Callee->getName()))];
OutlineFS->merge(*FS, 1);
// Set outlined profile to be synthetic to not bias the inliner.
OutlineFS->SetContextSynthetic();
}
} else {
auto pair =
notInlinedCallInfo.try_emplace(Callee, NotInlinedProfileInfo{0});
pair.first->second.entryCount += FS->getHeadSamplesEstimate();
}
}
}
/// Returns the sorted CallTargetMap \p M by count in descending order.
static SmallVector<InstrProfValueData, 2>
GetSortedValueDataFromCallTargets(const SampleRecord::CallTargetMap &M) {
SmallVector<InstrProfValueData, 2> R;
for (const auto &I : SampleRecord::SortCallTargets(M)) {
R.emplace_back(
InstrProfValueData{I.first.getHashCode(), I.second});
}
return R;
}
// Generate MD_prof metadata for every branch instruction using the
// edge weights computed during propagation.
void SampleProfileLoader::generateMDProfMetadata(Function &F) {
// Generate MD_prof metadata for every branch instruction using the
// edge weights computed during propagation.
LLVM_DEBUG(dbgs() << "\nPropagation complete. Setting branch weights\n");
LLVMContext &Ctx = F.getContext();
MDBuilder MDB(Ctx);
for (auto &BI : F) {
BasicBlock *BB = &BI;
if (BlockWeights[BB]) {
for (auto &I : *BB) {
if (!isa<CallInst>(I) && !isa<InvokeInst>(I))
continue;
if (!cast<CallBase>(I).getCalledFunction()) {
const DebugLoc &DLoc = I.getDebugLoc();
if (!DLoc)
continue;
const DILocation *DIL = DLoc;
const FunctionSamples *FS = findFunctionSamples(I);
if (!FS)
continue;
auto CallSite = FunctionSamples::getCallSiteIdentifier(DIL);
ErrorOr<SampleRecord::CallTargetMap> T =
FS->findCallTargetMapAt(CallSite);
if (!T || T.get().empty())
continue;
if (FunctionSamples::ProfileIsProbeBased) {
// Prorate the callsite counts based on the pre-ICP distribution
// factor to reflect what is already done to the callsite before
// ICP, such as calliste cloning.
if (std::optional<PseudoProbe> Probe = extractProbe(I)) {
if (Probe->Factor < 1)
T = SampleRecord::adjustCallTargets(T.get(), Probe->Factor);
}
}
SmallVector<InstrProfValueData, 2> SortedCallTargets =
GetSortedValueDataFromCallTargets(T.get());
uint64_t Sum = 0;
for (const auto &C : T.get())
Sum += C.second;
// With CSSPGO all indirect call targets are counted torwards the
// original indirect call site in the profile, including both
// inlined and non-inlined targets.
if (!FunctionSamples::ProfileIsCS) {
if (const FunctionSamplesMap *M =
FS->findFunctionSamplesMapAt(CallSite)) {
for (const auto &NameFS : *M)
Sum += NameFS.second.getHeadSamplesEstimate();
}
}
if (Sum)
updateIDTMetaData(I, SortedCallTargets, Sum);
else if (OverwriteExistingWeights)
I.setMetadata(LLVMContext::MD_prof, nullptr);
} else if (!isa<IntrinsicInst>(&I)) {
setBranchWeights(I, {static_cast<uint32_t>(BlockWeights[BB])});
}
}
} else if (OverwriteExistingWeights || ProfileSampleBlockAccurate) {
// Set profile metadata (possibly annotated by LTO prelink) to zero or
// clear it for cold code.
for (auto &I : *BB) {
if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
if (cast<CallBase>(I).isIndirectCall()) {
I.setMetadata(LLVMContext::MD_prof, nullptr);
} else {
setBranchWeights(I, {uint32_t(0)});
}
}
}
}
Instruction *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 1)
continue;
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI) &&
!isa<IndirectBrInst>(TI))
continue;
DebugLoc BranchLoc = TI->getDebugLoc();
LLVM_DEBUG(dbgs() << "\nGetting weights for branch at line "
<< ((BranchLoc) ? Twine(BranchLoc.getLine())
: Twine("<UNKNOWN LOCATION>"))
<< ".\n");
SmallVector<uint32_t, 4> Weights;
uint32_t MaxWeight = 0;
Instruction *MaxDestInst;
// Since profi treats multiple edges (multiway branches) as a single edge,
// we need to distribute the computed weight among the branches. We do
// this by evenly splitting the edge weight among destinations.
DenseMap<const BasicBlock *, uint64_t> EdgeMultiplicity;
std::vector<uint64_t> EdgeIndex;
if (SampleProfileUseProfi) {
EdgeIndex.resize(TI->getNumSuccessors());
for (unsigned I = 0; I < TI->getNumSuccessors(); ++I) {
const BasicBlock *Succ = TI->getSuccessor(I);
EdgeIndex[I] = EdgeMultiplicity[Succ];
EdgeMultiplicity[Succ]++;
}
}
for (unsigned I = 0; I < TI->getNumSuccessors(); ++I) {
BasicBlock *Succ = TI->getSuccessor(I);
Edge E = std::make_pair(BB, Succ);
uint64_t Weight = EdgeWeights[E];
LLVM_DEBUG(dbgs() << "\t"; printEdgeWeight(dbgs(), E));
// Use uint32_t saturated arithmetic to adjust the incoming weights,
// if needed. Sample counts in profiles are 64-bit unsigned values,
// but internally branch weights are expressed as 32-bit values.
if (Weight > std::numeric_limits<uint32_t>::max()) {
LLVM_DEBUG(dbgs() << " (saturated due to uint32_t overflow)\n");
Weight = std::numeric_limits<uint32_t>::max();
}
if (!SampleProfileUseProfi) {
// Weight is added by one to avoid propagation errors introduced by
// 0 weights.
Weights.push_back(static_cast<uint32_t>(
Weight == std::numeric_limits<uint32_t>::max() ? Weight
: Weight + 1));
} else {
// Profi creates proper weights that do not require "+1" adjustments but
// we evenly split the weight among branches with the same destination.
uint64_t W = Weight / EdgeMultiplicity[Succ];
// Rounding up, if needed, so that first branches are hotter.
if (EdgeIndex[I] < Weight % EdgeMultiplicity[Succ])
W++;
Weights.push_back(static_cast<uint32_t>(W));
}
if (Weight != 0) {
if (Weight > MaxWeight) {
MaxWeight = Weight;
MaxDestInst = Succ->getFirstNonPHIOrDbgOrLifetime();
}
}
}
misexpect::checkExpectAnnotations(*TI, Weights, /*IsFrontend=*/false);
uint64_t TempWeight;
// Only set weights if there is at least one non-zero weight.
// In any other case, let the analyzer set weights.
// Do not set weights if the weights are present unless under
// OverwriteExistingWeights. In ThinLTO, the profile annotation is done
// twice. If the first annotation already set the weights, the second pass
// does not need to set it. With OverwriteExistingWeights, Blocks with zero
// weight should have their existing metadata (possibly annotated by LTO
// prelink) cleared.
if (MaxWeight > 0 &&
(!TI->extractProfTotalWeight(TempWeight) || OverwriteExistingWeights)) {
LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n");
setBranchWeights(*TI, Weights);
ORE->emit([&]() {
return OptimizationRemark(DEBUG_TYPE, "PopularDest", MaxDestInst)
<< "most popular destination for conditional branches at "
<< ore::NV("CondBranchesLoc", BranchLoc);
});
} else {
if (OverwriteExistingWeights) {
TI->setMetadata(LLVMContext::MD_prof, nullptr);
LLVM_DEBUG(dbgs() << "CLEARED. All branch weights are zero.\n");
} else {
LLVM_DEBUG(dbgs() << "SKIPPED. All branch weights are zero.\n");
}
}
}
}
/// Once all the branch weights are computed, we emit the MD_prof
/// metadata on BB using the computed values for each of its branches.
///
/// \param F The function to query.
///
/// \returns true if \p F was modified. Returns false, otherwise.
bool SampleProfileLoader::emitAnnotations(Function &F) {
bool Changed = false;
if (FunctionSamples::ProfileIsProbeBased) {
LLVM_DEBUG({
if (!ProbeManager->getDesc(F))
dbgs() << "Probe descriptor missing for Function " << F.getName()
<< "\n";
});
if (ProbeManager->profileIsValid(F, *Samples)) {
++NumMatchedProfile;
} else {
++NumMismatchedProfile;
LLVM_DEBUG(
dbgs() << "Profile is invalid due to CFG mismatch for Function "
<< F.getName() << "\n");
if (!SalvageStaleProfile)
return false;
}
} else {
if (getFunctionLoc(F) == 0)
return false;
LLVM_DEBUG(dbgs() << "Line number for the first instruction in "
<< F.getName() << ": " << getFunctionLoc(F) << "\n");
}
DenseSet<GlobalValue::GUID> InlinedGUIDs;
if (CallsitePrioritizedInline)
Changed |= inlineHotFunctionsWithPriority(F, InlinedGUIDs);
else
Changed |= inlineHotFunctions(F, InlinedGUIDs);
Changed |= computeAndPropagateWeights(F, InlinedGUIDs);
if (Changed)
generateMDProfMetadata(F);
emitCoverageRemarks(F);
return Changed;
}
std::unique_ptr<ProfiledCallGraph>
SampleProfileLoader::buildProfiledCallGraph(Module &M) {
std::unique_ptr<ProfiledCallGraph> ProfiledCG;
if (FunctionSamples::ProfileIsCS)
ProfiledCG = std::make_unique<ProfiledCallGraph>(*ContextTracker);
else
ProfiledCG = std::make_unique<ProfiledCallGraph>(Reader->getProfiles());
// Add all functions into the profiled call graph even if they are not in
// the profile. This makes sure functions missing from the profile still
// gets a chance to be processed.
for (Function &F : M) {
if (skipProfileForFunction(F))
continue;
ProfiledCG->addProfiledFunction(
getRepInFormat(FunctionSamples::getCanonicalFnName(F)));
}
return ProfiledCG;
}
std::vector<Function *>
SampleProfileLoader::buildFunctionOrder(Module &M, LazyCallGraph &CG) {
std::vector<Function *> FunctionOrderList;
FunctionOrderList.reserve(M.size());
if (!ProfileTopDownLoad && UseProfiledCallGraph)
errs() << "WARNING: -use-profiled-call-graph ignored, should be used "
"together with -sample-profile-top-down-load.\n";
if (!ProfileTopDownLoad) {
if (ProfileMergeInlinee) {
// Disable ProfileMergeInlinee if profile is not loaded in top down order,
// because the profile for a function may be used for the profile
// annotation of its outline copy before the profile merging of its
// non-inlined inline instances, and that is not the way how
// ProfileMergeInlinee is supposed to work.
ProfileMergeInlinee = false;
}
for (Function &F : M)
if (!skipProfileForFunction(F))
FunctionOrderList.push_back(&F);
return FunctionOrderList;
}
if (UseProfiledCallGraph || (FunctionSamples::ProfileIsCS &&
!UseProfiledCallGraph.getNumOccurrences())) {
// Use profiled call edges to augment the top-down order. There are cases
// that the top-down order computed based on the static call graph doesn't
// reflect real execution order. For example
//
// 1. Incomplete static call graph due to unknown indirect call targets.
// Adjusting the order by considering indirect call edges from the
// profile can enable the inlining of indirect call targets by allowing
// the caller processed before them.
// 2. Mutual call edges in an SCC. The static processing order computed for
// an SCC may not reflect the call contexts in the context-sensitive
// profile, thus may cause potential inlining to be overlooked. The
// function order in one SCC is being adjusted to a top-down order based
// on the profile to favor more inlining. This is only a problem with CS
// profile.
// 3. Transitive indirect call edges due to inlining. When a callee function
// (say B) is inlined into a caller function (say A) in LTO prelink,
// every call edge originated from the callee B will be transferred to
// the caller A. If any transferred edge (say A->C) is indirect, the
// original profiled indirect edge B->C, even if considered, would not
// enforce a top-down order from the caller A to the potential indirect
// call target C in LTO postlink since the inlined callee B is gone from
// the static call graph.
// 4. #3 can happen even for direct call targets, due to functions defined
// in header files. A header function (say A), when included into source
// files, is defined multiple times but only one definition survives due
// to ODR. Therefore, the LTO prelink inlining done on those dropped
// definitions can be useless based on a local file scope. More
// importantly, the inlinee (say B), once fully inlined to a
// to-be-dropped A, will have no profile to consume when its outlined
// version is compiled. This can lead to a profile-less prelink
// compilation for the outlined version of B which may be called from
// external modules. while this isn't easy to fix, we rely on the
// postlink AutoFDO pipeline to optimize B. Since the survived copy of
// the A can be inlined in its local scope in prelink, it may not exist
// in the merged IR in postlink, and we'll need the profiled call edges
// to enforce a top-down order for the rest of the functions.
//
// Considering those cases, a profiled call graph completely independent of
// the static call graph is constructed based on profile data, where
// function objects are not even needed to handle case #3 and case 4.
//
// Note that static callgraph edges are completely ignored since they
// can be conflicting with profiled edges for cyclic SCCs and may result in
// an SCC order incompatible with profile-defined one. Using strictly
// profile order ensures a maximum inlining experience. On the other hand,
// static call edges are not so important when they don't correspond to a
// context in the profile.
std::unique_ptr<ProfiledCallGraph> ProfiledCG = buildProfiledCallGraph(M);
scc_iterator<ProfiledCallGraph *> CGI = scc_begin(ProfiledCG.get());
while (!CGI.isAtEnd()) {
auto Range = *CGI;
if (SortProfiledSCC) {
// Sort nodes in one SCC based on callsite hotness.
scc_member_iterator<ProfiledCallGraph *> SI(*CGI);
Range = *SI;
}
for (auto *Node : Range) {
Function *F = SymbolMap.lookup(Node->Name);
if (F && !skipProfileForFunction(*F))
FunctionOrderList.push_back(F);
}
++CGI;
}
} else {
CG.buildRefSCCs();
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs()) {
for (LazyCallGraph::SCC &C : RC) {
for (LazyCallGraph::Node &N : C) {
Function &F = N.getFunction();
if (!skipProfileForFunction(F))
FunctionOrderList.push_back(&F);
}
}
}
}
std::reverse(FunctionOrderList.begin(), FunctionOrderList.end());
LLVM_DEBUG({
dbgs() << "Function processing order:\n";
for (auto F : FunctionOrderList) {
dbgs() << F->getName() << "\n";
}
});
return FunctionOrderList;
}
bool SampleProfileLoader::doInitialization(Module &M,
FunctionAnalysisManager *FAM) {
auto &Ctx = M.getContext();
auto ReaderOrErr = SampleProfileReader::create(
Filename, Ctx, *FS, FSDiscriminatorPass::Base, RemappingFilename);
if (std::error_code EC = ReaderOrErr.getError()) {
std::string Msg = "Could not open profile: " + EC.message();
Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
return false;
}
Reader = std::move(ReaderOrErr.get());
Reader->setSkipFlatProf(LTOPhase == ThinOrFullLTOPhase::ThinLTOPostLink);
// set module before reading the profile so reader may be able to only
// read the function profiles which are used by the current module.
Reader->setModule(&M);
if (std::error_code EC = Reader->read()) {
std::string Msg = "profile reading failed: " + EC.message();
Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
return false;
}
PSL = Reader->getProfileSymbolList();
// While profile-sample-accurate is on, ignore symbol list.
ProfAccForSymsInList =
ProfileAccurateForSymsInList && PSL && !ProfileSampleAccurate;
if (ProfAccForSymsInList) {
NamesInProfile.clear();
GUIDsInProfile.clear();
if (auto NameTable = Reader->getNameTable()) {
if (FunctionSamples::UseMD5) {
for (auto Name : *NameTable)
GUIDsInProfile.insert(Name.getHashCode());
} else {
for (auto Name : *NameTable)
NamesInProfile.insert(Name.stringRef());
}
}
CoverageTracker.setProfAccForSymsInList(true);
}
if (FAM && !ProfileInlineReplayFile.empty()) {
ExternalInlineAdvisor = getReplayInlineAdvisor(
M, *FAM, Ctx, /*OriginalAdvisor=*/nullptr,
ReplayInlinerSettings{ProfileInlineReplayFile,
ProfileInlineReplayScope,
ProfileInlineReplayFallback,
{ProfileInlineReplayFormat}},
/*EmitRemarks=*/false, InlineContext{LTOPhase, InlinePass::ReplaySampleProfileInliner});
}
// Apply tweaks if context-sensitive or probe-based profile is available.
if (Reader->profileIsCS() || Reader->profileIsPreInlined() ||
Reader->profileIsProbeBased()) {
if (!UseIterativeBFIInference.getNumOccurrences())
UseIterativeBFIInference = true;
if (!SampleProfileUseProfi.getNumOccurrences())
SampleProfileUseProfi = true;
if (!EnableExtTspBlockPlacement.getNumOccurrences())
EnableExtTspBlockPlacement = true;
// Enable priority-base inliner and size inline by default for CSSPGO.
if (!ProfileSizeInline.getNumOccurrences())
ProfileSizeInline = true;
if (!CallsitePrioritizedInline.getNumOccurrences())
CallsitePrioritizedInline = true;
// For CSSPGO, we also allow recursive inline to best use context profile.
if (!AllowRecursiveInline.getNumOccurrences())
AllowRecursiveInline = true;
if (Reader->profileIsPreInlined()) {
if (!UsePreInlinerDecision.getNumOccurrences())
UsePreInlinerDecision = true;
}
// Enable stale profile matching by default for probe-based profile.
// Currently the matching relies on if the checksum mismatch is detected,
// which is currently only available for pseudo-probe mode. Removing the
// checksum check could cause regressions for some cases, so further tuning
// might be needed if we want to enable it for all cases.
if (Reader->profileIsProbeBased() &&
!SalvageStaleProfile.getNumOccurrences()) {
SalvageStaleProfile = true;
}
if (!Reader->profileIsCS()) {
// Non-CS profile should be fine without a function size budget for the
// inliner since the contexts in the profile are either all from inlining
// in the prevoius build or pre-computed by the preinliner with a size
// cap, thus they are bounded.
if (!ProfileInlineLimitMin.getNumOccurrences())
ProfileInlineLimitMin = std::numeric_limits<unsigned>::max();
if (!ProfileInlineLimitMax.getNumOccurrences())
ProfileInlineLimitMax = std::numeric_limits<unsigned>::max();
}
}
if (Reader->profileIsCS()) {
// Tracker for profiles under different context
ContextTracker = std::make_unique<SampleContextTracker>(
Reader->getProfiles(), &GUIDToFuncNameMap);
}
// Load pseudo probe descriptors for probe-based function samples.
if (Reader->profileIsProbeBased()) {
ProbeManager = std::make_unique<PseudoProbeManager>(M);
if (!ProbeManager->moduleIsProbed(M)) {
const char *Msg =
"Pseudo-probe-based profile requires SampleProfileProbePass";
Ctx.diagnose(DiagnosticInfoSampleProfile(M.getModuleIdentifier(), Msg,
DS_Warning));
return false;
}
}
if (ReportProfileStaleness || PersistProfileStaleness ||
SalvageStaleProfile) {
MatchingManager = std::make_unique<SampleProfileMatcher>(
M, *Reader, ProbeManager.get(), LTOPhase);
}
return true;
}
// Note that this is a module-level check. Even if one module is errored out,
// the entire build will be errored out. However, the user could make big
// changes to functions in single module but those changes might not be
// performance significant to the whole binary. Therefore, to avoid those false
// positives, we select a reasonable big set of hot functions that are supposed
// to be globally performance significant, only compute and check the mismatch
// within those functions. The function selection is based on two criteria:
// 1) The function is hot enough, which is tuned by a hotness-based
// flag(HotFuncCutoffForStalenessError). 2) The num of function is large enough
// which is tuned by the MinfuncsForStalenessError flag.
bool SampleProfileLoader::rejectHighStalenessProfile(
Module &M, ProfileSummaryInfo *PSI, const SampleProfileMap &Profiles) {
assert(FunctionSamples::ProfileIsProbeBased &&
"Only support for probe-based profile");
uint64_t TotalHotFunc = 0;
uint64_t NumMismatchedFunc = 0;
for (const auto &I : Profiles) {
const auto &FS = I.second;
const auto *FuncDesc = ProbeManager->getDesc(FS.getGUID());
if (!FuncDesc)
continue;
// Use a hotness-based threshold to control the function selection.
if (!PSI->isHotCountNthPercentile(HotFuncCutoffForStalenessError,
FS.getTotalSamples()))
continue;
TotalHotFunc++;
if (ProbeManager->profileIsHashMismatched(*FuncDesc, FS))
NumMismatchedFunc++;
}
// Make sure that the num of selected function is not too small to distinguish
// from the user's benign changes.
if (TotalHotFunc < MinfuncsForStalenessError)
return false;
// Finally check the mismatch percentage against the threshold.
if (NumMismatchedFunc * 100 >=
TotalHotFunc * PrecentMismatchForStalenessError) {
auto &Ctx = M.getContext();
const char *Msg =
"The input profile significantly mismatches current source code. "
"Please recollect profile to avoid performance regression.";
Ctx.diagnose(DiagnosticInfoSampleProfile(M.getModuleIdentifier(), Msg));
return true;
}
return false;
}
void SampleProfileLoader::removePseudoProbeInsts(Module &M) {
for (auto &F : M) {
std::vector<Instruction *> InstsToDel;
for (auto &BB : F) {
for (auto &I : BB) {
if (isa<PseudoProbeInst>(&I))
InstsToDel.push_back(&I);
}
}
for (auto *I : InstsToDel)
I->eraseFromParent();
}
}
bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
ProfileSummaryInfo *_PSI,
LazyCallGraph &CG) {
GUIDToFuncNameMapper Mapper(M, *Reader, GUIDToFuncNameMap);
PSI = _PSI;
if (M.getProfileSummary(/* IsCS */ false) == nullptr) {
M.setProfileSummary(Reader->getSummary().getMD(M.getContext()),
ProfileSummary::PSK_Sample);
PSI->refresh();
}
if (FunctionSamples::ProfileIsProbeBased &&
rejectHighStalenessProfile(M, PSI, Reader->getProfiles()))
return false;
// Compute the total number of samples collected in this profile.
for (const auto &I : Reader->getProfiles())
TotalCollectedSamples += I.second.getTotalSamples();
auto Remapper = Reader->getRemapper();
// Populate the symbol map.
for (const auto &N_F : M.getValueSymbolTable()) {
StringRef OrigName = N_F.getKey();
Function *F = dyn_cast<Function>(N_F.getValue());
if (F == nullptr || OrigName.empty())
continue;
SymbolMap[FunctionId(OrigName)] = F;
StringRef NewName = FunctionSamples::getCanonicalFnName(*F);
if (OrigName != NewName && !NewName.empty()) {
auto r = SymbolMap.emplace(FunctionId(NewName), F);
// Failiing to insert means there is already an entry in SymbolMap,
// thus there are multiple functions that are mapped to the same
// stripped name. In this case of name conflicting, set the value
// to nullptr to avoid confusion.
if (!r.second)
r.first->second = nullptr;
OrigName = NewName;
}
// Insert the remapped names into SymbolMap.
if (Remapper) {
if (auto MapName = Remapper->lookUpNameInProfile(OrigName)) {
if (*MapName != OrigName && !MapName->empty())
SymbolMap.emplace(FunctionId(*MapName), F);
}
}
}
assert(SymbolMap.count(FunctionId()) == 0 &&
"No empty StringRef should be added in SymbolMap");
if (ReportProfileStaleness || PersistProfileStaleness ||
SalvageStaleProfile) {
MatchingManager->runOnModule();
MatchingManager->clearMatchingData();
}
bool retval = false;
for (auto *F : buildFunctionOrder(M, CG)) {
assert(!F->isDeclaration());
clearFunctionData();
retval |= runOnFunction(*F, AM);
}
// Account for cold calls not inlined....
if (!FunctionSamples::ProfileIsCS)
for (const std::pair<Function *, NotInlinedProfileInfo> &pair :
notInlinedCallInfo)
updateProfileCallee(pair.first, pair.second.entryCount);
if (RemoveProbeAfterProfileAnnotation && FunctionSamples::ProfileIsProbeBased)
removePseudoProbeInsts(M);
return retval;
}
bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM) {
LLVM_DEBUG(dbgs() << "\n\nProcessing Function " << F.getName() << "\n");
DILocation2SampleMap.clear();
// By default the entry count is initialized to -1, which will be treated
// conservatively by getEntryCount as the same as unknown (None). This is
// to avoid newly added code to be treated as cold. If we have samples
// this will be overwritten in emitAnnotations.
uint64_t initialEntryCount = -1;
ProfAccForSymsInList = ProfileAccurateForSymsInList && PSL;
if (ProfileSampleAccurate || F.hasFnAttribute("profile-sample-accurate")) {
// initialize all the function entry counts to 0. It means all the
// functions without profile will be regarded as cold.
initialEntryCount = 0;
// profile-sample-accurate is a user assertion which has a higher precedence
// than symbol list. When profile-sample-accurate is on, ignore symbol list.
ProfAccForSymsInList = false;
}
CoverageTracker.setProfAccForSymsInList(ProfAccForSymsInList);
// PSL -- profile symbol list include all the symbols in sampled binary.
// If ProfileAccurateForSymsInList is enabled, PSL is used to treat
// old functions without samples being cold, without having to worry
// about new and hot functions being mistakenly treated as cold.
if (ProfAccForSymsInList) {
// Initialize the entry count to 0 for functions in the list.
if (PSL->contains(F.getName()))
initialEntryCount = 0;
// Function in the symbol list but without sample will be regarded as
// cold. To minimize the potential negative performance impact it could
// have, we want to be a little conservative here saying if a function
// shows up in the profile, no matter as outline function, inline instance
// or call targets, treat the function as not being cold. This will handle
// the cases such as most callsites of a function are inlined in sampled
// binary but not inlined in current build (because of source code drift,
// imprecise debug information, or the callsites are all cold individually
// but not cold accumulatively...), so the outline function showing up as
// cold in sampled binary will actually not be cold after current build.
StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
if ((FunctionSamples::UseMD5 &&
GUIDsInProfile.count(Function::getGUID(CanonName))) ||
(!FunctionSamples::UseMD5 && NamesInProfile.count(CanonName)))
initialEntryCount = -1;
}
// Initialize entry count when the function has no existing entry
// count value.
if (!F.getEntryCount())
F.setEntryCount(ProfileCount(initialEntryCount, Function::PCT_Real));
std::unique_ptr<OptimizationRemarkEmitter> OwnedORE;
if (AM) {
auto &FAM =
AM->getResult<FunctionAnalysisManagerModuleProxy>(*F.getParent())
.getManager();
ORE = &FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
} else {
OwnedORE = std::make_unique<OptimizationRemarkEmitter>(&F);
ORE = OwnedORE.get();
}
if (FunctionSamples::ProfileIsCS)
Samples = ContextTracker->getBaseSamplesFor(F);
else {
Samples = Reader->getSamplesFor(F);
// Try search in previously inlined functions that were split or duplicated
// into base.
if (!Samples) {
StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
auto It = OutlineFunctionSamples.find(FunctionId(CanonName));
if (It != OutlineFunctionSamples.end()) {
Samples = &It->second;
} else if (auto Remapper = Reader->getRemapper()) {
if (auto RemppedName = Remapper->lookUpNameInProfile(CanonName)) {
It = OutlineFunctionSamples.find(FunctionId(*RemppedName));
if (It != OutlineFunctionSamples.end())
Samples = &It->second;
}
}
}
}
if (Samples && !Samples->empty())
return emitAnnotations(F);
return false;
}
SampleProfileLoaderPass::SampleProfileLoaderPass(
std::string File, std::string RemappingFile, ThinOrFullLTOPhase LTOPhase,
IntrusiveRefCntPtr<vfs::FileSystem> FS)
: ProfileFileName(File), ProfileRemappingFileName(RemappingFile),
LTOPhase(LTOPhase), FS(std::move(FS)) {}
PreservedAnalyses SampleProfileLoaderPass::run(Module &M,
ModuleAnalysisManager &AM) {
FunctionAnalysisManager &FAM =
AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
auto GetAssumptionCache = [&](Function &F) -> AssumptionCache & {
return FAM.getResult<AssumptionAnalysis>(F);
};
auto GetTTI = [&](Function &F) -> TargetTransformInfo & {
return FAM.getResult<TargetIRAnalysis>(F);
};
auto GetTLI = [&](Function &F) -> const TargetLibraryInfo & {
return FAM.getResult<TargetLibraryAnalysis>(F);
};
if (!FS)
FS = vfs::getRealFileSystem();
SampleProfileLoader SampleLoader(
ProfileFileName.empty() ? SampleProfileFile : ProfileFileName,
ProfileRemappingFileName.empty() ? SampleProfileRemappingFile
: ProfileRemappingFileName,
LTOPhase, FS, GetAssumptionCache, GetTTI, GetTLI);
if (!SampleLoader.doInitialization(M, &FAM))
return PreservedAnalyses::all();
ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
LazyCallGraph &CG = AM.getResult<LazyCallGraphAnalysis>(M);
if (!SampleLoader.runOnModule(M, &AM, PSI, CG))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}