forked from OSchip/llvm-project
1629 lines
62 KiB
C++
1629 lines
62 KiB
C++
//===- SampleProfile.cpp - Incorporate sample profiles into the IR --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the SampleProfileLoader transformation. This pass
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// reads a profile file generated by a sampling profiler (e.g. Linux Perf -
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// http://perf.wiki.kernel.org/) and generates IR metadata to reflect the
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// profile information in the given profile.
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//
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// This pass generates branch weight annotations on the IR:
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//
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// - prof: Represents branch weights. This annotation is added to branches
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// to indicate the weights of each edge coming out of the branch.
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// The weight of each edge is the weight of the target block for
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// that edge. The weight of a block B is computed as the maximum
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// number of samples found in B.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO/SampleProfile.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/None.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/OptimizationRemarkEmitter.h"
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#include "llvm/Analysis/PostDominators.h"
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#include "llvm/Analysis/ProfileSummaryInfo.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/DebugInfoMetadata.h"
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#include "llvm/IR/DebugLoc.h"
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#include "llvm/IR/DiagnosticInfo.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/MDBuilder.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/IR/ValueSymbolTable.h"
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#include "llvm/Pass.h"
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#include "llvm/ProfileData/InstrProf.h"
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#include "llvm/ProfileData/SampleProf.h"
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#include "llvm/ProfileData/SampleProfReader.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/GenericDomTree.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Transforms/Instrumentation.h"
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#include "llvm/Transforms/Utils/CallPromotionUtils.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include <algorithm>
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#include <cassert>
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#include <cstdint>
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#include <functional>
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#include <limits>
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#include <map>
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#include <memory>
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#include <string>
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#include <system_error>
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#include <utility>
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#include <vector>
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using namespace llvm;
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using namespace sampleprof;
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using ProfileCount = Function::ProfileCount;
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#define DEBUG_TYPE "sample-profile"
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// Command line option to specify the file to read samples from. This is
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// mainly used for debugging.
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static cl::opt<std::string> SampleProfileFile(
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"sample-profile-file", cl::init(""), cl::value_desc("filename"),
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cl::desc("Profile file loaded by -sample-profile"), cl::Hidden);
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static cl::opt<unsigned> SampleProfileMaxPropagateIterations(
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"sample-profile-max-propagate-iterations", cl::init(100),
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cl::desc("Maximum number of iterations to go through when propagating "
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"sample block/edge weights through the CFG."));
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static cl::opt<unsigned> SampleProfileRecordCoverage(
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"sample-profile-check-record-coverage", cl::init(0), cl::value_desc("N"),
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cl::desc("Emit a warning if less than N% of records in the input profile "
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"are matched to the IR."));
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static cl::opt<unsigned> SampleProfileSampleCoverage(
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"sample-profile-check-sample-coverage", cl::init(0), cl::value_desc("N"),
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cl::desc("Emit a warning if less than N% of samples in the input profile "
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"are matched to the IR."));
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static cl::opt<bool> NoWarnSampleUnused(
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"no-warn-sample-unused", cl::init(false), cl::Hidden,
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cl::desc("Use this option to turn off/on warnings about function with "
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"samples but without debug information to use those samples. "));
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namespace {
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using BlockWeightMap = DenseMap<const BasicBlock *, uint64_t>;
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using EquivalenceClassMap = DenseMap<const BasicBlock *, const BasicBlock *>;
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using Edge = std::pair<const BasicBlock *, const BasicBlock *>;
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using EdgeWeightMap = DenseMap<Edge, uint64_t>;
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using BlockEdgeMap =
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DenseMap<const BasicBlock *, SmallVector<const BasicBlock *, 8>>;
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class SampleCoverageTracker {
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public:
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SampleCoverageTracker() = default;
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bool markSamplesUsed(const FunctionSamples *FS, uint32_t LineOffset,
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uint32_t Discriminator, uint64_t Samples);
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unsigned computeCoverage(unsigned Used, unsigned Total) const;
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unsigned countUsedRecords(const FunctionSamples *FS,
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ProfileSummaryInfo *PSI) const;
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unsigned countBodyRecords(const FunctionSamples *FS,
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ProfileSummaryInfo *PSI) const;
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uint64_t getTotalUsedSamples() const { return TotalUsedSamples; }
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uint64_t countBodySamples(const FunctionSamples *FS,
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ProfileSummaryInfo *PSI) const;
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void clear() {
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SampleCoverage.clear();
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TotalUsedSamples = 0;
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}
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private:
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using BodySampleCoverageMap = std::map<LineLocation, unsigned>;
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using FunctionSamplesCoverageMap =
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DenseMap<const FunctionSamples *, BodySampleCoverageMap>;
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/// Coverage map for sampling records.
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///
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/// This map keeps a record of sampling records that have been matched to
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/// an IR instruction. This is used to detect some form of staleness in
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/// profiles (see flag -sample-profile-check-coverage).
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///
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/// Each entry in the map corresponds to a FunctionSamples instance. This is
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/// another map that counts how many times the sample record at the
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/// given location has been used.
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FunctionSamplesCoverageMap SampleCoverage;
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/// Number of samples used from the profile.
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///
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/// When a sampling record is used for the first time, the samples from
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/// that record are added to this accumulator. Coverage is later computed
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/// based on the total number of samples available in this function and
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/// its callsites.
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///
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/// Note that this accumulator tracks samples used from a single function
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/// and all the inlined callsites. Strictly, we should have a map of counters
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/// keyed by FunctionSamples pointers, but these stats are cleared after
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/// every function, so we just need to keep a single counter.
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uint64_t TotalUsedSamples = 0;
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};
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/// Sample profile pass.
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///
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/// This pass reads profile data from the file specified by
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/// -sample-profile-file and annotates every affected function with the
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/// profile information found in that file.
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class SampleProfileLoader {
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public:
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SampleProfileLoader(
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StringRef Name, bool IsThinLTOPreLink,
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std::function<AssumptionCache &(Function &)> GetAssumptionCache,
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std::function<TargetTransformInfo &(Function &)> GetTargetTransformInfo)
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: GetAC(std::move(GetAssumptionCache)),
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GetTTI(std::move(GetTargetTransformInfo)), Filename(Name),
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IsThinLTOPreLink(IsThinLTOPreLink) {}
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bool doInitialization(Module &M);
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bool runOnModule(Module &M, ModuleAnalysisManager *AM,
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ProfileSummaryInfo *_PSI);
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void dump() { Reader->dump(); }
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protected:
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bool runOnFunction(Function &F, ModuleAnalysisManager *AM);
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unsigned getFunctionLoc(Function &F);
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bool emitAnnotations(Function &F);
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ErrorOr<uint64_t> getInstWeight(const Instruction &I);
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ErrorOr<uint64_t> getBlockWeight(const BasicBlock *BB);
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const FunctionSamples *findCalleeFunctionSamples(const Instruction &I) const;
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std::vector<const FunctionSamples *>
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findIndirectCallFunctionSamples(const Instruction &I, uint64_t &Sum) const;
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const FunctionSamples *findFunctionSamples(const Instruction &I) const;
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bool inlineCallInstruction(Instruction *I);
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bool inlineHotFunctions(Function &F,
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DenseSet<GlobalValue::GUID> &InlinedGUIDs);
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void printEdgeWeight(raw_ostream &OS, Edge E);
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void printBlockWeight(raw_ostream &OS, const BasicBlock *BB) const;
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void printBlockEquivalence(raw_ostream &OS, const BasicBlock *BB);
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bool computeBlockWeights(Function &F);
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void findEquivalenceClasses(Function &F);
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template <bool IsPostDom>
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void findEquivalencesFor(BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
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DominatorTreeBase<BasicBlock, IsPostDom> *DomTree);
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void propagateWeights(Function &F);
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uint64_t visitEdge(Edge E, unsigned *NumUnknownEdges, Edge *UnknownEdge);
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void buildEdges(Function &F);
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bool propagateThroughEdges(Function &F, bool UpdateBlockCount);
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void computeDominanceAndLoopInfo(Function &F);
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void clearFunctionData();
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/// Map basic blocks to their computed weights.
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///
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/// The weight of a basic block is defined to be the maximum
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/// of all the instruction weights in that block.
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BlockWeightMap BlockWeights;
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/// Map edges to their computed weights.
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///
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/// Edge weights are computed by propagating basic block weights in
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/// SampleProfile::propagateWeights.
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EdgeWeightMap EdgeWeights;
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/// Set of visited blocks during propagation.
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SmallPtrSet<const BasicBlock *, 32> VisitedBlocks;
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/// Set of visited edges during propagation.
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SmallSet<Edge, 32> VisitedEdges;
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/// Equivalence classes for block weights.
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///
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/// Two blocks BB1 and BB2 are in the same equivalence class if they
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/// dominate and post-dominate each other, and they are in the same loop
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/// nest. When this happens, the two blocks are guaranteed to execute
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/// the same number of times.
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EquivalenceClassMap EquivalenceClass;
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/// Map from function name to Function *. Used to find the function from
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/// the function name. If the function name contains suffix, additional
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/// entry is added to map from the stripped name to the function if there
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/// is one-to-one mapping.
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StringMap<Function *> SymbolMap;
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/// Dominance, post-dominance and loop information.
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std::unique_ptr<DominatorTree> DT;
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std::unique_ptr<PostDominatorTree> PDT;
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std::unique_ptr<LoopInfo> LI;
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std::function<AssumptionCache &(Function &)> GetAC;
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std::function<TargetTransformInfo &(Function &)> GetTTI;
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/// Predecessors for each basic block in the CFG.
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BlockEdgeMap Predecessors;
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/// Successors for each basic block in the CFG.
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BlockEdgeMap Successors;
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SampleCoverageTracker CoverageTracker;
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/// Profile reader object.
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std::unique_ptr<SampleProfileReader> Reader;
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/// Samples collected for the body of this function.
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FunctionSamples *Samples = nullptr;
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/// Name of the profile file to load.
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std::string Filename;
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/// Flag indicating whether the profile input loaded successfully.
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bool ProfileIsValid = false;
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/// Flag indicating if the pass is invoked in ThinLTO compile phase.
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///
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/// In this phase, in annotation, we should not promote indirect calls.
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/// Instead, we will mark GUIDs that needs to be annotated to the function.
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bool IsThinLTOPreLink;
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/// Profile Summary Info computed from sample profile.
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ProfileSummaryInfo *PSI = nullptr;
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/// Total number of samples collected in this profile.
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///
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/// This is the sum of all the samples collected in all the functions executed
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/// at runtime.
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uint64_t TotalCollectedSamples = 0;
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/// Optimization Remark Emitter used to emit diagnostic remarks.
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OptimizationRemarkEmitter *ORE = nullptr;
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};
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class SampleProfileLoaderLegacyPass : public ModulePass {
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public:
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// Class identification, replacement for typeinfo
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static char ID;
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SampleProfileLoaderLegacyPass(StringRef Name = SampleProfileFile,
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bool IsThinLTOPreLink = false)
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: ModulePass(ID), SampleLoader(Name, IsThinLTOPreLink,
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[&](Function &F) -> AssumptionCache & {
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return ACT->getAssumptionCache(F);
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},
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[&](Function &F) -> TargetTransformInfo & {
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return TTIWP->getTTI(F);
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}) {
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initializeSampleProfileLoaderLegacyPassPass(
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*PassRegistry::getPassRegistry());
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}
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void dump() { SampleLoader.dump(); }
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bool doInitialization(Module &M) override {
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return SampleLoader.doInitialization(M);
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}
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StringRef getPassName() const override { return "Sample profile pass"; }
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bool runOnModule(Module &M) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<AssumptionCacheTracker>();
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AU.addRequired<TargetTransformInfoWrapperPass>();
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AU.addRequired<ProfileSummaryInfoWrapperPass>();
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}
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private:
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SampleProfileLoader SampleLoader;
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AssumptionCacheTracker *ACT = nullptr;
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TargetTransformInfoWrapperPass *TTIWP = nullptr;
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};
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} // end anonymous namespace
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/// Return true if the given callsite is hot wrt to hot cutoff threshold.
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///
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/// Functions that were inlined in the original binary will be represented
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/// in the inline stack in the sample profile. If the profile shows that
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/// the original inline decision was "good" (i.e., the callsite is executed
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/// frequently), then we will recreate the inline decision and apply the
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/// profile from the inlined callsite.
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///
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/// To decide whether an inlined callsite is hot, we compare the callsite
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/// sample count with the hot cutoff computed by ProfileSummaryInfo, it is
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/// regarded as hot if the count is above the cutoff value.
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static bool callsiteIsHot(const FunctionSamples *CallsiteFS,
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ProfileSummaryInfo *PSI) {
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if (!CallsiteFS)
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return false; // The callsite was not inlined in the original binary.
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assert(PSI && "PSI is expected to be non null");
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uint64_t CallsiteTotalSamples = CallsiteFS->getTotalSamples();
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return PSI->isHotCount(CallsiteTotalSamples);
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}
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/// Mark as used the sample record for the given function samples at
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/// (LineOffset, Discriminator).
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///
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/// \returns true if this is the first time we mark the given record.
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bool SampleCoverageTracker::markSamplesUsed(const FunctionSamples *FS,
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uint32_t LineOffset,
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uint32_t Discriminator,
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uint64_t Samples) {
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LineLocation Loc(LineOffset, Discriminator);
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unsigned &Count = SampleCoverage[FS][Loc];
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bool FirstTime = (++Count == 1);
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if (FirstTime)
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TotalUsedSamples += Samples;
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return FirstTime;
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}
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/// Return the number of sample records that were applied from this profile.
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///
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/// This count does not include records from cold inlined callsites.
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unsigned
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SampleCoverageTracker::countUsedRecords(const FunctionSamples *FS,
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ProfileSummaryInfo *PSI) const {
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auto I = SampleCoverage.find(FS);
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// The size of the coverage map for FS represents the number of records
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// that were marked used at least once.
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unsigned Count = (I != SampleCoverage.end()) ? I->second.size() : 0;
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// If there are inlined callsites in this function, count the samples found
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// in the respective bodies. However, do not bother counting callees with 0
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// total samples, these are callees that were never invoked at runtime.
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for (const auto &I : FS->getCallsiteSamples())
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for (const auto &J : I.second) {
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const FunctionSamples *CalleeSamples = &J.second;
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if (callsiteIsHot(CalleeSamples, PSI))
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Count += countUsedRecords(CalleeSamples, PSI);
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}
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return Count;
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}
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/// Return the number of sample records in the body of this profile.
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///
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/// This count does not include records from cold inlined callsites.
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unsigned
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SampleCoverageTracker::countBodyRecords(const FunctionSamples *FS,
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ProfileSummaryInfo *PSI) const {
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unsigned Count = FS->getBodySamples().size();
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// Only count records in hot callsites.
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for (const auto &I : FS->getCallsiteSamples())
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for (const auto &J : I.second) {
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const FunctionSamples *CalleeSamples = &J.second;
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if (callsiteIsHot(CalleeSamples, PSI))
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Count += countBodyRecords(CalleeSamples, PSI);
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}
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return Count;
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}
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/// Return the number of samples collected in the body of this profile.
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///
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/// This count does not include samples from cold inlined callsites.
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uint64_t
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SampleCoverageTracker::countBodySamples(const FunctionSamples *FS,
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ProfileSummaryInfo *PSI) const {
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uint64_t Total = 0;
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for (const auto &I : FS->getBodySamples())
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Total += I.second.getSamples();
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// Only count samples in hot callsites.
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for (const auto &I : FS->getCallsiteSamples())
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for (const auto &J : I.second) {
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const FunctionSamples *CalleeSamples = &J.second;
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if (callsiteIsHot(CalleeSamples, PSI))
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Total += countBodySamples(CalleeSamples, PSI);
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}
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return Total;
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}
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/// Return the fraction of sample records used in this profile.
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///
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/// The returned value is an unsigned integer in the range 0-100 indicating
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/// the percentage of sample records that were used while applying this
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/// profile to the associated function.
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unsigned SampleCoverageTracker::computeCoverage(unsigned Used,
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unsigned Total) const {
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assert(Used <= Total &&
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"number of used records cannot exceed the total number of records");
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return Total > 0 ? Used * 100 / Total : 100;
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}
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/// Clear all the per-function data used to load samples and propagate weights.
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void SampleProfileLoader::clearFunctionData() {
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BlockWeights.clear();
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EdgeWeights.clear();
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VisitedBlocks.clear();
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VisitedEdges.clear();
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EquivalenceClass.clear();
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DT = nullptr;
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PDT = nullptr;
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LI = nullptr;
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Predecessors.clear();
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Successors.clear();
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CoverageTracker.clear();
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}
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#ifndef NDEBUG
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/// Print the weight of edge \p E on stream \p OS.
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///
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/// \param OS Stream to emit the output to.
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/// \param E Edge to print.
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void SampleProfileLoader::printEdgeWeight(raw_ostream &OS, Edge E) {
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OS << "weight[" << E.first->getName() << "->" << E.second->getName()
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<< "]: " << EdgeWeights[E] << "\n";
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}
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|
|
/// Print the equivalence class of block \p BB on stream \p OS.
|
|
///
|
|
/// \param OS Stream to emit the output to.
|
|
/// \param BB Block to print.
|
|
void SampleProfileLoader::printBlockEquivalence(raw_ostream &OS,
|
|
const BasicBlock *BB) {
|
|
const BasicBlock *Equiv = EquivalenceClass[BB];
|
|
OS << "equivalence[" << BB->getName()
|
|
<< "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
|
|
}
|
|
|
|
/// Print the weight of block \p BB on stream \p OS.
|
|
///
|
|
/// \param OS Stream to emit the output to.
|
|
/// \param BB Block to print.
|
|
void SampleProfileLoader::printBlockWeight(raw_ostream &OS,
|
|
const BasicBlock *BB) const {
|
|
const auto &I = BlockWeights.find(BB);
|
|
uint64_t W = (I == BlockWeights.end() ? 0 : I->second);
|
|
OS << "weight[" << BB->getName() << "]: " << W << "\n";
|
|
}
|
|
#endif
|
|
|
|
/// Get the weight for an instruction.
|
|
///
|
|
/// The "weight" of an instruction \p Inst is the number of samples
|
|
/// collected on that instruction at runtime. To retrieve it, we
|
|
/// need to compute the line number of \p Inst relative to the start of its
|
|
/// function. We use HeaderLineno to compute the offset. We then
|
|
/// look up the samples collected for \p Inst using BodySamples.
|
|
///
|
|
/// \param Inst Instruction to query.
|
|
///
|
|
/// \returns the weight of \p Inst.
|
|
ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
|
|
const DebugLoc &DLoc = Inst.getDebugLoc();
|
|
if (!DLoc)
|
|
return std::error_code();
|
|
|
|
const FunctionSamples *FS = findFunctionSamples(Inst);
|
|
if (!FS)
|
|
return std::error_code();
|
|
|
|
// Ignore all intrinsics and branch instructions.
|
|
// Branch 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))
|
|
return std::error_code();
|
|
|
|
// 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.
|
|
if ((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
|
|
!ImmutableCallSite(&Inst).isIndirectCall() &&
|
|
findCalleeFunctionSamples(Inst))
|
|
return 0;
|
|
|
|
const DILocation *DIL = DLoc;
|
|
uint32_t LineOffset = FunctionSamples::getOffset(DIL);
|
|
uint32_t Discriminator = DIL->getBaseDiscriminator();
|
|
ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
|
|
if (R) {
|
|
bool FirstMark =
|
|
CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator, R.get());
|
|
if (FirstMark) {
|
|
ORE->emit([&]() {
|
|
OptimizationRemarkAnalysis Remark(DEBUG_TYPE, "AppliedSamples", &Inst);
|
|
Remark << "Applied " << ore::NV("NumSamples", *R);
|
|
Remark << " samples from profile (offset: ";
|
|
Remark << ore::NV("LineOffset", LineOffset);
|
|
if (Discriminator) {
|
|
Remark << ".";
|
|
Remark << ore::NV("Discriminator", Discriminator);
|
|
}
|
|
Remark << ")";
|
|
return Remark;
|
|
});
|
|
}
|
|
LLVM_DEBUG(dbgs() << " " << DLoc.getLine() << "."
|
|
<< DIL->getBaseDiscriminator() << ":" << Inst
|
|
<< " (line offset: " << LineOffset << "."
|
|
<< DIL->getBaseDiscriminator() << " - weight: " << R.get()
|
|
<< ")\n");
|
|
}
|
|
return R;
|
|
}
|
|
|
|
/// Compute the weight of a basic block.
|
|
///
|
|
/// The weight of basic block \p BB is the maximum weight of all the
|
|
/// instructions in BB.
|
|
///
|
|
/// \param BB The basic block to query.
|
|
///
|
|
/// \returns the weight for \p BB.
|
|
ErrorOr<uint64_t> SampleProfileLoader::getBlockWeight(const BasicBlock *BB) {
|
|
uint64_t Max = 0;
|
|
bool HasWeight = false;
|
|
for (auto &I : BB->getInstList()) {
|
|
const ErrorOr<uint64_t> &R = getInstWeight(I);
|
|
if (R) {
|
|
Max = std::max(Max, R.get());
|
|
HasWeight = true;
|
|
}
|
|
}
|
|
return HasWeight ? ErrorOr<uint64_t>(Max) : std::error_code();
|
|
}
|
|
|
|
/// Compute and store the weights of every basic block.
|
|
///
|
|
/// This populates the BlockWeights map by computing
|
|
/// the weights of every basic block in the CFG.
|
|
///
|
|
/// \param F The function to query.
|
|
bool SampleProfileLoader::computeBlockWeights(Function &F) {
|
|
bool Changed = false;
|
|
LLVM_DEBUG(dbgs() << "Block weights\n");
|
|
for (const auto &BB : F) {
|
|
ErrorOr<uint64_t> Weight = getBlockWeight(&BB);
|
|
if (Weight) {
|
|
BlockWeights[&BB] = Weight.get();
|
|
VisitedBlocks.insert(&BB);
|
|
Changed = true;
|
|
}
|
|
LLVM_DEBUG(printBlockWeight(dbgs(), &BB));
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// 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 Instruction &Inst) const {
|
|
const DILocation *DIL = Inst.getDebugLoc();
|
|
if (!DIL) {
|
|
return nullptr;
|
|
}
|
|
|
|
StringRef CalleeName;
|
|
if (const CallInst *CI = dyn_cast<CallInst>(&Inst))
|
|
if (Function *Callee = CI->getCalledFunction())
|
|
CalleeName = Callee->getName();
|
|
|
|
const FunctionSamples *FS = findFunctionSamples(Inst);
|
|
if (FS == nullptr)
|
|
return nullptr;
|
|
|
|
std::string CalleeGUID;
|
|
CalleeName = getRepInFormat(CalleeName, Reader->getFormat(), CalleeGUID);
|
|
return FS->findFunctionSamplesAt(LineLocation(FunctionSamples::getOffset(DIL),
|
|
DIL->getBaseDiscriminator()),
|
|
CalleeName);
|
|
}
|
|
|
|
/// 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;
|
|
}
|
|
|
|
const FunctionSamples *FS = findFunctionSamples(Inst);
|
|
if (FS == nullptr)
|
|
return R;
|
|
|
|
uint32_t LineOffset = FunctionSamples::getOffset(DIL);
|
|
uint32_t Discriminator = DIL->getBaseDiscriminator();
|
|
|
|
auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
|
|
Sum = 0;
|
|
if (T)
|
|
for (const auto &T_C : T.get())
|
|
Sum += T_C.second;
|
|
if (const FunctionSamplesMap *M = FS->findFunctionSamplesMapAt(LineLocation(
|
|
FunctionSamples::getOffset(DIL), DIL->getBaseDiscriminator()))) {
|
|
if (M->empty())
|
|
return R;
|
|
for (const auto &NameFS : *M) {
|
|
Sum += NameFS.second.getEntrySamples();
|
|
R.push_back(&NameFS.second);
|
|
}
|
|
llvm::sort(R.begin(), R.end(),
|
|
[](const FunctionSamples *L, const FunctionSamples *R) {
|
|
return L->getEntrySamples() > R->getEntrySamples();
|
|
});
|
|
}
|
|
return R;
|
|
}
|
|
|
|
/// Get the FunctionSamples for an instruction.
|
|
///
|
|
/// The FunctionSamples of an instruction \p Inst is the inlined instance
|
|
/// in which that instruction is coming from. We traverse the inline stack
|
|
/// of that instruction, and match it with the tree nodes in the profile.
|
|
///
|
|
/// \param Inst Instruction to query.
|
|
///
|
|
/// \returns the FunctionSamples pointer to the inlined instance.
|
|
const FunctionSamples *
|
|
SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
|
|
SmallVector<std::pair<LineLocation, StringRef>, 10> S;
|
|
const DILocation *DIL = Inst.getDebugLoc();
|
|
if (!DIL)
|
|
return Samples;
|
|
|
|
return Samples->findFunctionSamples(DIL);
|
|
}
|
|
|
|
bool SampleProfileLoader::inlineCallInstruction(Instruction *I) {
|
|
assert(isa<CallInst>(I) || isa<InvokeInst>(I));
|
|
CallSite CS(I);
|
|
Function *CalledFunction = CS.getCalledFunction();
|
|
assert(CalledFunction);
|
|
DebugLoc DLoc = I->getDebugLoc();
|
|
BasicBlock *BB = I->getParent();
|
|
InlineParams Params = getInlineParams();
|
|
Params.ComputeFullInlineCost = true;
|
|
// 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(CS, Params, GetTTI(*CalledFunction), GetAC,
|
|
None, nullptr, nullptr);
|
|
if (Cost.isNever()) {
|
|
ORE->emit(OptimizationRemark(DEBUG_TYPE, "Not inline", DLoc, BB)
|
|
<< "incompatible inlining");
|
|
return false;
|
|
}
|
|
InlineFunctionInfo IFI(nullptr, &GetAC);
|
|
if (InlineFunction(CS, IFI)) {
|
|
// The call to InlineFunction erases I, so we can't pass it here.
|
|
ORE->emit(OptimizationRemark(DEBUG_TYPE, "HotInline", DLoc, BB)
|
|
<< "inlined hot callee '" << ore::NV("Callee", CalledFunction)
|
|
<< "' into '" << ore::NV("Caller", BB->getParent()) << "'");
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// Iteratively inline hot callsites of a function.
|
|
///
|
|
/// Iteratively traverse all callsites of the function \p F, and find if
|
|
/// the corresponding inlined instance exists and is hot in profile. If
|
|
/// it is hot enough, inline the callsites and adds new 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.
|
|
///
|
|
/// \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) {
|
|
DenseSet<Instruction *> PromotedInsns;
|
|
bool Changed = false;
|
|
bool isCompact = (Reader->getFormat() == SPF_Compact_Binary);
|
|
while (true) {
|
|
bool LocalChanged = false;
|
|
SmallVector<Instruction *, 10> CIS;
|
|
for (auto &BB : F) {
|
|
bool Hot = false;
|
|
SmallVector<Instruction *, 10> Candidates;
|
|
for (auto &I : BB.getInstList()) {
|
|
const FunctionSamples *FS = nullptr;
|
|
if ((isa<CallInst>(I) || isa<InvokeInst>(I)) &&
|
|
!isa<IntrinsicInst>(I) && (FS = findCalleeFunctionSamples(I))) {
|
|
Candidates.push_back(&I);
|
|
if (callsiteIsHot(FS, PSI))
|
|
Hot = true;
|
|
}
|
|
}
|
|
if (Hot) {
|
|
CIS.insert(CIS.begin(), Candidates.begin(), Candidates.end());
|
|
}
|
|
}
|
|
for (auto I : CIS) {
|
|
Function *CalledFunction = CallSite(I).getCalledFunction();
|
|
// Do not inline recursive calls.
|
|
if (CalledFunction == &F)
|
|
continue;
|
|
if (CallSite(I).isIndirectCall()) {
|
|
if (PromotedInsns.count(I))
|
|
continue;
|
|
uint64_t Sum;
|
|
for (const auto *FS : findIndirectCallFunctionSamples(*I, Sum)) {
|
|
if (IsThinLTOPreLink) {
|
|
FS->findInlinedFunctions(InlinedGUIDs, F.getParent(),
|
|
PSI->getOrCompHotCountThreshold(),
|
|
isCompact);
|
|
continue;
|
|
}
|
|
auto CalleeFunctionName = FS->getName();
|
|
// 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.
|
|
std::string FGUID;
|
|
auto Fname = getRepInFormat(F.getName(), Reader->getFormat(), FGUID);
|
|
if (CalleeFunctionName == Fname)
|
|
continue;
|
|
|
|
const char *Reason = "Callee function not available";
|
|
auto R = SymbolMap.find(CalleeFunctionName);
|
|
if (R != SymbolMap.end() && R->getValue() &&
|
|
!R->getValue()->isDeclaration() &&
|
|
R->getValue()->getSubprogram() &&
|
|
isLegalToPromote(CallSite(I), R->getValue(), &Reason)) {
|
|
uint64_t C = FS->getEntrySamples();
|
|
Instruction *DI =
|
|
pgo::promoteIndirectCall(I, R->getValue(), C, Sum, false, ORE);
|
|
Sum -= C;
|
|
PromotedInsns.insert(I);
|
|
// If profile mismatches, we should not attempt to inline DI.
|
|
if ((isa<CallInst>(DI) || isa<InvokeInst>(DI)) &&
|
|
inlineCallInstruction(DI))
|
|
LocalChanged = true;
|
|
} else {
|
|
LLVM_DEBUG(dbgs()
|
|
<< "\nFailed to promote indirect call to "
|
|
<< CalleeFunctionName << " because " << Reason << "\n");
|
|
}
|
|
}
|
|
} else if (CalledFunction && CalledFunction->getSubprogram() &&
|
|
!CalledFunction->isDeclaration()) {
|
|
if (inlineCallInstruction(I))
|
|
LocalChanged = true;
|
|
} else if (IsThinLTOPreLink) {
|
|
findCalleeFunctionSamples(*I)->findInlinedFunctions(
|
|
InlinedGUIDs, F.getParent(), PSI->getOrCompHotCountThreshold(),
|
|
isCompact);
|
|
}
|
|
}
|
|
if (LocalChanged) {
|
|
Changed = true;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
/// Find equivalence classes for the given block.
|
|
///
|
|
/// This finds all the blocks that are guaranteed to execute the same
|
|
/// number of times as \p BB1. To do this, it traverses all the
|
|
/// descendants of \p BB1 in the dominator or post-dominator tree.
|
|
///
|
|
/// A block BB2 will be in the same equivalence class as \p BB1 if
|
|
/// the following holds:
|
|
///
|
|
/// 1- \p BB1 is a descendant of BB2 in the opposite tree. So, if BB2
|
|
/// is a descendant of \p BB1 in the dominator tree, then BB2 should
|
|
/// dominate BB1 in the post-dominator tree.
|
|
///
|
|
/// 2- Both BB2 and \p BB1 must be in the same loop.
|
|
///
|
|
/// For every block BB2 that meets those two requirements, we set BB2's
|
|
/// equivalence class to \p BB1.
|
|
///
|
|
/// \param BB1 Block to check.
|
|
/// \param Descendants Descendants of \p BB1 in either the dom or pdom tree.
|
|
/// \param DomTree Opposite dominator tree. If \p Descendants is filled
|
|
/// with blocks from \p BB1's dominator tree, then
|
|
/// this is the post-dominator tree, and vice versa.
|
|
template <bool IsPostDom>
|
|
void SampleProfileLoader::findEquivalencesFor(
|
|
BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
|
|
DominatorTreeBase<BasicBlock, IsPostDom> *DomTree) {
|
|
const BasicBlock *EC = EquivalenceClass[BB1];
|
|
uint64_t Weight = BlockWeights[EC];
|
|
for (const auto *BB2 : Descendants) {
|
|
bool IsDomParent = DomTree->dominates(BB2, BB1);
|
|
bool IsInSameLoop = LI->getLoopFor(BB1) == LI->getLoopFor(BB2);
|
|
if (BB1 != BB2 && IsDomParent && IsInSameLoop) {
|
|
EquivalenceClass[BB2] = EC;
|
|
// If BB2 is visited, then the entire EC should be marked as visited.
|
|
if (VisitedBlocks.count(BB2)) {
|
|
VisitedBlocks.insert(EC);
|
|
}
|
|
|
|
// If BB2 is heavier than BB1, make BB2 have the same weight
|
|
// as BB1.
|
|
//
|
|
// Note that we don't worry about the opposite situation here
|
|
// (when BB2 is lighter than BB1). We will deal with this
|
|
// during the propagation phase. Right now, we just want to
|
|
// make sure that BB1 has the largest weight of all the
|
|
// members of its equivalence set.
|
|
Weight = std::max(Weight, BlockWeights[BB2]);
|
|
}
|
|
}
|
|
if (EC == &EC->getParent()->getEntryBlock()) {
|
|
BlockWeights[EC] = Samples->getHeadSamples() + 1;
|
|
} else {
|
|
BlockWeights[EC] = Weight;
|
|
}
|
|
}
|
|
|
|
/// Find equivalence classes.
|
|
///
|
|
/// Since samples may be missing from blocks, we can fill in the gaps by setting
|
|
/// the weights of all the blocks in the same equivalence class to the same
|
|
/// weight. To compute the concept of equivalence, we use dominance and loop
|
|
/// information. Two blocks B1 and B2 are in the same equivalence class if B1
|
|
/// dominates B2, B2 post-dominates B1 and both are in the same loop.
|
|
///
|
|
/// \param F The function to query.
|
|
void SampleProfileLoader::findEquivalenceClasses(Function &F) {
|
|
SmallVector<BasicBlock *, 8> DominatedBBs;
|
|
LLVM_DEBUG(dbgs() << "\nBlock equivalence classes\n");
|
|
// Find equivalence sets based on dominance and post-dominance information.
|
|
for (auto &BB : F) {
|
|
BasicBlock *BB1 = &BB;
|
|
|
|
// Compute BB1's equivalence class once.
|
|
if (EquivalenceClass.count(BB1)) {
|
|
LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
|
|
continue;
|
|
}
|
|
|
|
// By default, blocks are in their own equivalence class.
|
|
EquivalenceClass[BB1] = BB1;
|
|
|
|
// Traverse all the blocks dominated by BB1. We are looking for
|
|
// every basic block BB2 such that:
|
|
//
|
|
// 1- BB1 dominates BB2.
|
|
// 2- BB2 post-dominates BB1.
|
|
// 3- BB1 and BB2 are in the same loop nest.
|
|
//
|
|
// If all those conditions hold, it means that BB2 is executed
|
|
// as many times as BB1, so they are placed in the same equivalence
|
|
// class by making BB2's equivalence class be BB1.
|
|
DominatedBBs.clear();
|
|
DT->getDescendants(BB1, DominatedBBs);
|
|
findEquivalencesFor(BB1, DominatedBBs, PDT.get());
|
|
|
|
LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
|
|
}
|
|
|
|
// Assign weights to equivalence classes.
|
|
//
|
|
// All the basic blocks in the same equivalence class will execute
|
|
// the same number of times. Since we know that the head block in
|
|
// each equivalence class has the largest weight, assign that weight
|
|
// to all the blocks in that equivalence class.
|
|
LLVM_DEBUG(
|
|
dbgs() << "\nAssign the same weight to all blocks in the same class\n");
|
|
for (auto &BI : F) {
|
|
const BasicBlock *BB = &BI;
|
|
const BasicBlock *EquivBB = EquivalenceClass[BB];
|
|
if (BB != EquivBB)
|
|
BlockWeights[BB] = BlockWeights[EquivBB];
|
|
LLVM_DEBUG(printBlockWeight(dbgs(), BB));
|
|
}
|
|
}
|
|
|
|
/// Visit the given edge to decide if it has a valid weight.
|
|
///
|
|
/// If \p E has not been visited before, we copy to \p UnknownEdge
|
|
/// and increment the count of unknown edges.
|
|
///
|
|
/// \param E Edge to visit.
|
|
/// \param NumUnknownEdges Current number of unknown edges.
|
|
/// \param UnknownEdge Set if E has not been visited before.
|
|
///
|
|
/// \returns E's weight, if known. Otherwise, return 0.
|
|
uint64_t SampleProfileLoader::visitEdge(Edge E, unsigned *NumUnknownEdges,
|
|
Edge *UnknownEdge) {
|
|
if (!VisitedEdges.count(E)) {
|
|
(*NumUnknownEdges)++;
|
|
*UnknownEdge = E;
|
|
return 0;
|
|
}
|
|
|
|
return EdgeWeights[E];
|
|
}
|
|
|
|
/// Propagate weights through incoming/outgoing edges.
|
|
///
|
|
/// If the weight of a basic block is known, and there is only one edge
|
|
/// with an unknown weight, we can calculate the weight of that edge.
|
|
///
|
|
/// Similarly, if all the edges have a known count, we can calculate the
|
|
/// count of the basic block, if needed.
|
|
///
|
|
/// \param F Function to process.
|
|
/// \param UpdateBlockCount Whether we should update basic block counts that
|
|
/// has already been annotated.
|
|
///
|
|
/// \returns True if new weights were assigned to edges or blocks.
|
|
bool SampleProfileLoader::propagateThroughEdges(Function &F,
|
|
bool UpdateBlockCount) {
|
|
bool Changed = false;
|
|
LLVM_DEBUG(dbgs() << "\nPropagation through edges\n");
|
|
for (const auto &BI : F) {
|
|
const BasicBlock *BB = &BI;
|
|
const BasicBlock *EC = EquivalenceClass[BB];
|
|
|
|
// Visit all the predecessor and successor edges to determine
|
|
// which ones have a weight assigned already. Note that it doesn't
|
|
// matter that we only keep track of a single unknown edge. The
|
|
// only case we are interested in handling is when only a single
|
|
// edge is unknown (see setEdgeOrBlockWeight).
|
|
for (unsigned i = 0; i < 2; i++) {
|
|
uint64_t TotalWeight = 0;
|
|
unsigned NumUnknownEdges = 0, NumTotalEdges = 0;
|
|
Edge UnknownEdge, SelfReferentialEdge, SingleEdge;
|
|
|
|
if (i == 0) {
|
|
// First, visit all predecessor edges.
|
|
NumTotalEdges = Predecessors[BB].size();
|
|
for (auto *Pred : Predecessors[BB]) {
|
|
Edge E = std::make_pair(Pred, BB);
|
|
TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
|
|
if (E.first == E.second)
|
|
SelfReferentialEdge = E;
|
|
}
|
|
if (NumTotalEdges == 1) {
|
|
SingleEdge = std::make_pair(Predecessors[BB][0], BB);
|
|
}
|
|
} else {
|
|
// On the second round, visit all successor edges.
|
|
NumTotalEdges = Successors[BB].size();
|
|
for (auto *Succ : Successors[BB]) {
|
|
Edge E = std::make_pair(BB, Succ);
|
|
TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
|
|
}
|
|
if (NumTotalEdges == 1) {
|
|
SingleEdge = std::make_pair(BB, Successors[BB][0]);
|
|
}
|
|
}
|
|
|
|
// After visiting all the edges, there are three cases that we
|
|
// can handle immediately:
|
|
//
|
|
// - All the edge weights are known (i.e., NumUnknownEdges == 0).
|
|
// In this case, we simply check that the sum of all the edges
|
|
// is the same as BB's weight. If not, we change BB's weight
|
|
// to match. Additionally, if BB had not been visited before,
|
|
// we mark it visited.
|
|
//
|
|
// - Only one edge is unknown and BB has already been visited.
|
|
// In this case, we can compute the weight of the edge by
|
|
// subtracting the total block weight from all the known
|
|
// edge weights. If the edges weight more than BB, then the
|
|
// edge of the last remaining edge is set to zero.
|
|
//
|
|
// - There exists a self-referential edge and the weight of BB is
|
|
// known. In this case, this edge can be based on BB's weight.
|
|
// We add up all the other known edges and set the weight on
|
|
// the self-referential edge as we did in the previous case.
|
|
//
|
|
// In any other case, we must continue iterating. Eventually,
|
|
// all edges will get a weight, or iteration will stop when
|
|
// it reaches SampleProfileMaxPropagateIterations.
|
|
if (NumUnknownEdges <= 1) {
|
|
uint64_t &BBWeight = BlockWeights[EC];
|
|
if (NumUnknownEdges == 0) {
|
|
if (!VisitedBlocks.count(EC)) {
|
|
// If we already know the weight of all edges, the weight of the
|
|
// basic block can be computed. It should be no larger than the sum
|
|
// of all edge weights.
|
|
if (TotalWeight > BBWeight) {
|
|
BBWeight = TotalWeight;
|
|
Changed = true;
|
|
LLVM_DEBUG(dbgs() << "All edge weights for " << BB->getName()
|
|
<< " known. Set weight for block: ";
|
|
printBlockWeight(dbgs(), BB););
|
|
}
|
|
} else if (NumTotalEdges == 1 &&
|
|
EdgeWeights[SingleEdge] < BlockWeights[EC]) {
|
|
// If there is only one edge for the visited basic block, use the
|
|
// block weight to adjust edge weight if edge weight is smaller.
|
|
EdgeWeights[SingleEdge] = BlockWeights[EC];
|
|
Changed = true;
|
|
}
|
|
} else if (NumUnknownEdges == 1 && VisitedBlocks.count(EC)) {
|
|
// If there is a single unknown edge and the block has been
|
|
// visited, then we can compute E's weight.
|
|
if (BBWeight >= TotalWeight)
|
|
EdgeWeights[UnknownEdge] = BBWeight - TotalWeight;
|
|
else
|
|
EdgeWeights[UnknownEdge] = 0;
|
|
const BasicBlock *OtherEC;
|
|
if (i == 0)
|
|
OtherEC = EquivalenceClass[UnknownEdge.first];
|
|
else
|
|
OtherEC = EquivalenceClass[UnknownEdge.second];
|
|
// Edge weights should never exceed the BB weights it connects.
|
|
if (VisitedBlocks.count(OtherEC) &&
|
|
EdgeWeights[UnknownEdge] > BlockWeights[OtherEC])
|
|
EdgeWeights[UnknownEdge] = BlockWeights[OtherEC];
|
|
VisitedEdges.insert(UnknownEdge);
|
|
Changed = true;
|
|
LLVM_DEBUG(dbgs() << "Set weight for edge: ";
|
|
printEdgeWeight(dbgs(), UnknownEdge));
|
|
}
|
|
} else if (VisitedBlocks.count(EC) && BlockWeights[EC] == 0) {
|
|
// If a block Weights 0, all its in/out edges should weight 0.
|
|
if (i == 0) {
|
|
for (auto *Pred : Predecessors[BB]) {
|
|
Edge E = std::make_pair(Pred, BB);
|
|
EdgeWeights[E] = 0;
|
|
VisitedEdges.insert(E);
|
|
}
|
|
} else {
|
|
for (auto *Succ : Successors[BB]) {
|
|
Edge E = std::make_pair(BB, Succ);
|
|
EdgeWeights[E] = 0;
|
|
VisitedEdges.insert(E);
|
|
}
|
|
}
|
|
} else if (SelfReferentialEdge.first && VisitedBlocks.count(EC)) {
|
|
uint64_t &BBWeight = BlockWeights[BB];
|
|
// We have a self-referential edge and the weight of BB is known.
|
|
if (BBWeight >= TotalWeight)
|
|
EdgeWeights[SelfReferentialEdge] = BBWeight - TotalWeight;
|
|
else
|
|
EdgeWeights[SelfReferentialEdge] = 0;
|
|
VisitedEdges.insert(SelfReferentialEdge);
|
|
Changed = true;
|
|
LLVM_DEBUG(dbgs() << "Set self-referential edge weight to: ";
|
|
printEdgeWeight(dbgs(), SelfReferentialEdge));
|
|
}
|
|
if (UpdateBlockCount && !VisitedBlocks.count(EC) && TotalWeight > 0) {
|
|
BlockWeights[EC] = TotalWeight;
|
|
VisitedBlocks.insert(EC);
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// Build in/out edge lists for each basic block in the CFG.
|
|
///
|
|
/// We are interested in unique edges. If a block B1 has multiple
|
|
/// edges to another block B2, we only add a single B1->B2 edge.
|
|
void SampleProfileLoader::buildEdges(Function &F) {
|
|
for (auto &BI : F) {
|
|
BasicBlock *B1 = &BI;
|
|
|
|
// Add predecessors for B1.
|
|
SmallPtrSet<BasicBlock *, 16> Visited;
|
|
if (!Predecessors[B1].empty())
|
|
llvm_unreachable("Found a stale predecessors list in a basic block.");
|
|
for (pred_iterator PI = pred_begin(B1), PE = pred_end(B1); PI != PE; ++PI) {
|
|
BasicBlock *B2 = *PI;
|
|
if (Visited.insert(B2).second)
|
|
Predecessors[B1].push_back(B2);
|
|
}
|
|
|
|
// Add successors for B1.
|
|
Visited.clear();
|
|
if (!Successors[B1].empty())
|
|
llvm_unreachable("Found a stale successors list in a basic block.");
|
|
for (succ_iterator SI = succ_begin(B1), SE = succ_end(B1); SI != SE; ++SI) {
|
|
BasicBlock *B2 = *SI;
|
|
if (Visited.insert(B2).second)
|
|
Successors[B1].push_back(B2);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns the sorted CallTargetMap \p M by count in descending order.
|
|
static SmallVector<InstrProfValueData, 2> SortCallTargets(
|
|
const SampleRecord::CallTargetMap &M) {
|
|
SmallVector<InstrProfValueData, 2> R;
|
|
for (auto I = M.begin(); I != M.end(); ++I)
|
|
R.push_back({Function::getGUID(I->getKey()), I->getValue()});
|
|
llvm::sort(R.begin(), R.end(),
|
|
[](const InstrProfValueData &L, const InstrProfValueData &R) {
|
|
if (L.Count == R.Count)
|
|
return L.Value > R.Value;
|
|
else
|
|
return L.Count > R.Count;
|
|
});
|
|
return R;
|
|
}
|
|
|
|
/// Propagate weights into edges
|
|
///
|
|
/// The following rules are applied to every block BB in the CFG:
|
|
///
|
|
/// - If BB has a single predecessor/successor, then the weight
|
|
/// of that edge is the weight of the block.
|
|
///
|
|
/// - If all incoming or outgoing edges are known except one, and the
|
|
/// weight of the block is already known, the weight of the unknown
|
|
/// edge will be the weight of the block minus the sum of all the known
|
|
/// edges. If the sum of all the known edges is larger than BB's weight,
|
|
/// we set the unknown edge weight to zero.
|
|
///
|
|
/// - If there is a self-referential edge, and the weight of the block is
|
|
/// known, the weight for that edge is set to the weight of the block
|
|
/// minus the weight of the other incoming edges to that block (if
|
|
/// known).
|
|
void SampleProfileLoader::propagateWeights(Function &F) {
|
|
bool Changed = true;
|
|
unsigned I = 0;
|
|
|
|
// If BB weight is larger than its corresponding loop's header BB weight,
|
|
// use the BB weight to replace the loop header BB weight.
|
|
for (auto &BI : F) {
|
|
BasicBlock *BB = &BI;
|
|
Loop *L = LI->getLoopFor(BB);
|
|
if (!L) {
|
|
continue;
|
|
}
|
|
BasicBlock *Header = L->getHeader();
|
|
if (Header && BlockWeights[BB] > BlockWeights[Header]) {
|
|
BlockWeights[Header] = BlockWeights[BB];
|
|
}
|
|
}
|
|
|
|
// Before propagation starts, build, for each block, a list of
|
|
// unique predecessors and successors. This is necessary to handle
|
|
// identical edges in multiway branches. Since we visit all blocks and all
|
|
// edges of the CFG, it is cleaner to build these lists once at the start
|
|
// of the pass.
|
|
buildEdges(F);
|
|
|
|
// Propagate until we converge or we go past the iteration limit.
|
|
while (Changed && I++ < SampleProfileMaxPropagateIterations) {
|
|
Changed = propagateThroughEdges(F, false);
|
|
}
|
|
|
|
// The first propagation propagates BB counts from annotated BBs to unknown
|
|
// BBs. The 2nd propagation pass resets edges weights, and use all BB weights
|
|
// to propagate edge weights.
|
|
VisitedEdges.clear();
|
|
Changed = true;
|
|
while (Changed && I++ < SampleProfileMaxPropagateIterations) {
|
|
Changed = propagateThroughEdges(F, false);
|
|
}
|
|
|
|
// The 3rd propagation pass allows adjust annotated BB weights that are
|
|
// obviously wrong.
|
|
Changed = true;
|
|
while (Changed && I++ < SampleProfileMaxPropagateIterations) {
|
|
Changed = propagateThroughEdges(F, true);
|
|
}
|
|
|
|
// 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->getInstList()) {
|
|
if (!isa<CallInst>(I) && !isa<InvokeInst>(I))
|
|
continue;
|
|
CallSite CS(&I);
|
|
if (!CS.getCalledFunction()) {
|
|
const DebugLoc &DLoc = I.getDebugLoc();
|
|
if (!DLoc)
|
|
continue;
|
|
const DILocation *DIL = DLoc;
|
|
uint32_t LineOffset = FunctionSamples::getOffset(DIL);
|
|
uint32_t Discriminator = DIL->getBaseDiscriminator();
|
|
|
|
const FunctionSamples *FS = findFunctionSamples(I);
|
|
if (!FS)
|
|
continue;
|
|
auto T = FS->findCallTargetMapAt(LineOffset, Discriminator);
|
|
if (!T || T.get().empty())
|
|
continue;
|
|
SmallVector<InstrProfValueData, 2> SortedCallTargets =
|
|
SortCallTargets(T.get());
|
|
uint64_t Sum;
|
|
findIndirectCallFunctionSamples(I, Sum);
|
|
annotateValueSite(*I.getParent()->getParent()->getParent(), I,
|
|
SortedCallTargets, Sum, IPVK_IndirectCallTarget,
|
|
SortedCallTargets.size());
|
|
} else if (!dyn_cast<IntrinsicInst>(&I)) {
|
|
SmallVector<uint32_t, 1> Weights;
|
|
Weights.push_back(BlockWeights[BB]);
|
|
I.setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
|
|
}
|
|
}
|
|
}
|
|
TerminatorInst *TI = BB->getTerminator();
|
|
if (TI->getNumSuccessors() == 1)
|
|
continue;
|
|
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(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;
|
|
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)");
|
|
Weight = std::numeric_limits<uint32_t>::max();
|
|
}
|
|
// Weight is added by one to avoid propagation errors introduced by
|
|
// 0 weights.
|
|
Weights.push_back(static_cast<uint32_t>(Weight + 1));
|
|
if (Weight != 0) {
|
|
if (Weight > MaxWeight) {
|
|
MaxWeight = Weight;
|
|
MaxDestInst = Succ->getFirstNonPHIOrDbgOrLifetime();
|
|
}
|
|
}
|
|
}
|
|
|
|
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. 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.
|
|
if (MaxWeight > 0 && !TI->extractProfTotalWeight(TempWeight)) {
|
|
LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n");
|
|
TI->setMetadata(LLVMContext::MD_prof,
|
|
MDB.createBranchWeights(Weights));
|
|
ORE->emit([&]() {
|
|
return OptimizationRemark(DEBUG_TYPE, "PopularDest", MaxDestInst)
|
|
<< "most popular destination for conditional branches at "
|
|
<< ore::NV("CondBranchesLoc", BranchLoc);
|
|
});
|
|
} else {
|
|
LLVM_DEBUG(dbgs() << "SKIPPED. All branch weights are zero.\n");
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Get the line number for the function header.
|
|
///
|
|
/// This looks up function \p F in the current compilation unit and
|
|
/// retrieves the line number where the function is defined. This is
|
|
/// line 0 for all the samples read from the profile file. Every line
|
|
/// number is relative to this line.
|
|
///
|
|
/// \param F Function object to query.
|
|
///
|
|
/// \returns the line number where \p F is defined. If it returns 0,
|
|
/// it means that there is no debug information available for \p F.
|
|
unsigned SampleProfileLoader::getFunctionLoc(Function &F) {
|
|
if (DISubprogram *S = F.getSubprogram())
|
|
return S->getLine();
|
|
|
|
if (NoWarnSampleUnused)
|
|
return 0;
|
|
|
|
// If the start of \p F is missing, emit a diagnostic to inform the user
|
|
// about the missed opportunity.
|
|
F.getContext().diagnose(DiagnosticInfoSampleProfile(
|
|
"No debug information found in function " + F.getName() +
|
|
": Function profile not used",
|
|
DS_Warning));
|
|
return 0;
|
|
}
|
|
|
|
void SampleProfileLoader::computeDominanceAndLoopInfo(Function &F) {
|
|
DT.reset(new DominatorTree);
|
|
DT->recalculate(F);
|
|
|
|
PDT.reset(new PostDominatorTree(F));
|
|
|
|
LI.reset(new LoopInfo);
|
|
LI->analyze(*DT);
|
|
}
|
|
|
|
/// Generate branch weight metadata for all branches in \p F.
|
|
///
|
|
/// Branch weights are computed out of instruction samples using a
|
|
/// propagation heuristic. Propagation proceeds in 3 phases:
|
|
///
|
|
/// 1- Assignment of block weights. All the basic blocks in the function
|
|
/// are initial assigned the same weight as their most frequently
|
|
/// executed instruction.
|
|
///
|
|
/// 2- Creation of equivalence classes. Since samples may be missing from
|
|
/// blocks, we can fill in the gaps by setting the weights of all the
|
|
/// blocks in the same equivalence class to the same weight. To compute
|
|
/// the concept of equivalence, we use dominance and loop information.
|
|
/// Two blocks B1 and B2 are in the same equivalence class if B1
|
|
/// dominates B2, B2 post-dominates B1 and both are in the same loop.
|
|
///
|
|
/// 3- Propagation of block weights into edges. This uses a simple
|
|
/// propagation heuristic. The following rules are applied to every
|
|
/// block BB in the CFG:
|
|
///
|
|
/// - If BB has a single predecessor/successor, then the weight
|
|
/// of that edge is the weight of the block.
|
|
///
|
|
/// - If all the edges are known except one, and the weight of the
|
|
/// block is already known, the weight of the unknown edge will
|
|
/// be the weight of the block minus the sum of all the known
|
|
/// edges. If the sum of all the known edges is larger than BB's weight,
|
|
/// we set the unknown edge weight to zero.
|
|
///
|
|
/// - If there is a self-referential edge, and the weight of the block is
|
|
/// known, the weight for that edge is set to the weight of the block
|
|
/// minus the weight of the other incoming edges to that block (if
|
|
/// known).
|
|
///
|
|
/// Since this propagation is not guaranteed to finalize for every CFG, we
|
|
/// only allow it to proceed for a limited number of iterations (controlled
|
|
/// by -sample-profile-max-propagate-iterations).
|
|
///
|
|
/// FIXME: Try to replace this propagation heuristic with a scheme
|
|
/// that is guaranteed to finalize. A work-list approach similar to
|
|
/// the standard value propagation algorithm used by SSA-CCP might
|
|
/// work here.
|
|
///
|
|
/// 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 (getFunctionLoc(F) == 0)
|
|
return false;
|
|
|
|
LLVM_DEBUG(dbgs() << "Line number for the first instruction in "
|
|
<< F.getName() << ": " << getFunctionLoc(F) << "\n");
|
|
|
|
DenseSet<GlobalValue::GUID> InlinedGUIDs;
|
|
Changed |= inlineHotFunctions(F, InlinedGUIDs);
|
|
|
|
// Compute basic block weights.
|
|
Changed |= computeBlockWeights(F);
|
|
|
|
if (Changed) {
|
|
// Add an entry count to the function using the samples gathered at the
|
|
// function entry.
|
|
// Sets the GUIDs that are inlined in the profiled binary. This is used
|
|
// for ThinLink to make correct liveness analysis, and also make the IR
|
|
// match the profiled binary before annotation.
|
|
F.setEntryCount(
|
|
ProfileCount(Samples->getHeadSamples() + 1, Function::PCT_Real),
|
|
&InlinedGUIDs);
|
|
|
|
// Compute dominance and loop info needed for propagation.
|
|
computeDominanceAndLoopInfo(F);
|
|
|
|
// Find equivalence classes.
|
|
findEquivalenceClasses(F);
|
|
|
|
// Propagate weights to all edges.
|
|
propagateWeights(F);
|
|
}
|
|
|
|
// If coverage checking was requested, compute it now.
|
|
if (SampleProfileRecordCoverage) {
|
|
unsigned Used = CoverageTracker.countUsedRecords(Samples, PSI);
|
|
unsigned Total = CoverageTracker.countBodyRecords(Samples, PSI);
|
|
unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
|
|
if (Coverage < SampleProfileRecordCoverage) {
|
|
F.getContext().diagnose(DiagnosticInfoSampleProfile(
|
|
F.getSubprogram()->getFilename(), getFunctionLoc(F),
|
|
Twine(Used) + " of " + Twine(Total) + " available profile records (" +
|
|
Twine(Coverage) + "%) were applied",
|
|
DS_Warning));
|
|
}
|
|
}
|
|
|
|
if (SampleProfileSampleCoverage) {
|
|
uint64_t Used = CoverageTracker.getTotalUsedSamples();
|
|
uint64_t Total = CoverageTracker.countBodySamples(Samples, PSI);
|
|
unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
|
|
if (Coverage < SampleProfileSampleCoverage) {
|
|
F.getContext().diagnose(DiagnosticInfoSampleProfile(
|
|
F.getSubprogram()->getFilename(), getFunctionLoc(F),
|
|
Twine(Used) + " of " + Twine(Total) + " available profile samples (" +
|
|
Twine(Coverage) + "%) were applied",
|
|
DS_Warning));
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
char SampleProfileLoaderLegacyPass::ID = 0;
|
|
|
|
INITIALIZE_PASS_BEGIN(SampleProfileLoaderLegacyPass, "sample-profile",
|
|
"Sample Profile loader", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
|
|
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
|
|
INITIALIZE_PASS_END(SampleProfileLoaderLegacyPass, "sample-profile",
|
|
"Sample Profile loader", false, false)
|
|
|
|
bool SampleProfileLoader::doInitialization(Module &M) {
|
|
auto &Ctx = M.getContext();
|
|
auto ReaderOrErr = SampleProfileReader::create(Filename, Ctx);
|
|
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());
|
|
ProfileIsValid = (Reader->read() == sampleprof_error::success);
|
|
return true;
|
|
}
|
|
|
|
ModulePass *llvm::createSampleProfileLoaderPass() {
|
|
return new SampleProfileLoaderLegacyPass(SampleProfileFile);
|
|
}
|
|
|
|
ModulePass *llvm::createSampleProfileLoaderPass(StringRef Name) {
|
|
return new SampleProfileLoaderLegacyPass(Name);
|
|
}
|
|
|
|
bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
|
|
ProfileSummaryInfo *_PSI) {
|
|
if (!ProfileIsValid)
|
|
return false;
|
|
|
|
PSI = _PSI;
|
|
if (M.getProfileSummary() == nullptr)
|
|
M.setProfileSummary(Reader->getSummary().getMD(M.getContext()));
|
|
|
|
// Compute the total number of samples collected in this profile.
|
|
for (const auto &I : Reader->getProfiles())
|
|
TotalCollectedSamples += I.second.getTotalSamples();
|
|
|
|
// 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)
|
|
continue;
|
|
SymbolMap[OrigName] = F;
|
|
auto pos = OrigName.find('.');
|
|
if (pos != StringRef::npos) {
|
|
StringRef NewName = OrigName.substr(0, pos);
|
|
auto r = SymbolMap.insert(std::make_pair(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;
|
|
}
|
|
}
|
|
|
|
bool retval = false;
|
|
for (auto &F : M)
|
|
if (!F.isDeclaration()) {
|
|
clearFunctionData();
|
|
retval |= runOnFunction(F, AM);
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
bool SampleProfileLoaderLegacyPass::runOnModule(Module &M) {
|
|
ACT = &getAnalysis<AssumptionCacheTracker>();
|
|
TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
|
|
ProfileSummaryInfo *PSI =
|
|
getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
|
|
return SampleLoader.runOnModule(M, nullptr, PSI);
|
|
}
|
|
|
|
bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM) {
|
|
// Initialize the entry count to -1, which will be treated conservatively
|
|
// by getEntryCount as the same as unknown (None). If we have samples this
|
|
// will be overwritten in emitAnnotations.
|
|
F.setEntryCount(ProfileCount(-1, 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 = make_unique<OptimizationRemarkEmitter>(&F);
|
|
ORE = OwnedORE.get();
|
|
}
|
|
Samples = Reader->getSamplesFor(F);
|
|
if (Samples && !Samples->empty())
|
|
return emitAnnotations(F);
|
|
return false;
|
|
}
|
|
|
|
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);
|
|
};
|
|
|
|
SampleProfileLoader SampleLoader(
|
|
ProfileFileName.empty() ? SampleProfileFile : ProfileFileName,
|
|
IsThinLTOPreLink, GetAssumptionCache, GetTTI);
|
|
|
|
SampleLoader.doInitialization(M);
|
|
|
|
ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
|
|
if (!SampleLoader.runOnModule(M, &AM, PSI))
|
|
return PreservedAnalyses::all();
|
|
|
|
return PreservedAnalyses::none();
|
|
}
|