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llvm-project/llvm/lib/CodeGen/MIRSampleProfile.cpp

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//===-------- MIRSampleProfile.cpp: MIRSampleFDO (For FSAFDO) -------------===//
//
// 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 provides the implementation of the MIRSampleProfile loader, mainly
// for flow sensitive SampleFDO.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MIRSampleProfile.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h"
#include "llvm/Transforms/Utils/SampleProfileLoaderBaseUtil.h"
using namespace llvm;
using namespace sampleprof;
using namespace llvm::sampleprofutil;
using ProfileCount = Function::ProfileCount;
#define DEBUG_TYPE "fs-profile-loader"
static cl::opt<bool> ShowFSBranchProb(
"show-fs-branchprob", cl::Hidden, cl::init(false),
cl::desc("Print setting flow sensitive branch probabilities"));
static cl::opt<unsigned> FSProfileDebugProbDiffThreshold(
"fs-profile-debug-prob-diff-threshold", cl::init(10),
cl::desc("Only show debug message if the branch probility is greater than "
"this value (in percentage)."));
static cl::opt<unsigned> FSProfileDebugBWThreshold(
"fs-profile-debug-bw-threshold", cl::init(10000),
cl::desc("Only show debug message if the source branch weight is greater "
" than this value."));
static cl::opt<bool> ViewBFIBefore("fs-viewbfi-before", cl::Hidden,
cl::init(false),
cl::desc("View BFI before MIR loader"));
static cl::opt<bool> ViewBFIAfter("fs-viewbfi-after", cl::Hidden,
cl::init(false),
cl::desc("View BFI after MIR loader"));
char MIRProfileLoaderPass::ID = 0;
INITIALIZE_PASS_BEGIN(MIRProfileLoaderPass, DEBUG_TYPE,
"Load MIR Sample Profile",
/* cfg = */ false, /* is_analysis = */ false)
INITIALIZE_PASS_DEPENDENCY(MachineBlockFrequencyInfo)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachinePostDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_DEPENDENCY(MachineOptimizationRemarkEmitterPass)
INITIALIZE_PASS_END(MIRProfileLoaderPass, DEBUG_TYPE, "Load MIR Sample Profile",
/* cfg = */ false, /* is_analysis = */ false)
char &llvm::MIRProfileLoaderPassID = MIRProfileLoaderPass::ID;
FunctionPass *llvm::createMIRProfileLoaderPass(std::string File,
std::string RemappingFile,
FSDiscriminatorPass P) {
return new MIRProfileLoaderPass(File, RemappingFile, P);
}
namespace llvm {
// Internal option used to control BFI display only after MBP pass.
// Defined in CodeGen/MachineBlockFrequencyInfo.cpp:
// -view-block-layout-with-bfi={none | fraction | integer | count}
extern cl::opt<GVDAGType> ViewBlockLayoutWithBFI;
// Command line option to specify the name of the function for CFG dump
// Defined in Analysis/BlockFrequencyInfo.cpp: -view-bfi-func-name=
extern cl::opt<std::string> ViewBlockFreqFuncName;
namespace afdo_detail {
template <> struct IRTraits<MachineBasicBlock> {
using InstructionT = MachineInstr;
using BasicBlockT = MachineBasicBlock;
using FunctionT = MachineFunction;
using BlockFrequencyInfoT = MachineBlockFrequencyInfo;
using LoopT = MachineLoop;
using LoopInfoPtrT = MachineLoopInfo *;
using DominatorTreePtrT = MachineDominatorTree *;
using PostDominatorTreePtrT = MachinePostDominatorTree *;
using PostDominatorTreeT = MachinePostDominatorTree;
using OptRemarkEmitterT = MachineOptimizationRemarkEmitter;
using OptRemarkAnalysisT = MachineOptimizationRemarkAnalysis;
using PredRangeT = iterator_range<std::vector<MachineBasicBlock *>::iterator>;
using SuccRangeT = iterator_range<std::vector<MachineBasicBlock *>::iterator>;
static Function &getFunction(MachineFunction &F) { return F.getFunction(); }
static const MachineBasicBlock *getEntryBB(const MachineFunction *F) {
return GraphTraits<const MachineFunction *>::getEntryNode(F);
}
static PredRangeT getPredecessors(MachineBasicBlock *BB) {
return BB->predecessors();
}
static SuccRangeT getSuccessors(MachineBasicBlock *BB) {
return BB->successors();
}
};
} // namespace afdo_detail
class MIRProfileLoader final
: public SampleProfileLoaderBaseImpl<MachineBasicBlock> {
public:
void setInitVals(MachineDominatorTree *MDT, MachinePostDominatorTree *MPDT,
MachineLoopInfo *MLI, MachineBlockFrequencyInfo *MBFI,
MachineOptimizationRemarkEmitter *MORE) {
DT = MDT;
PDT = MPDT;
LI = MLI;
BFI = MBFI;
ORE = MORE;
}
void setFSPass(FSDiscriminatorPass Pass) {
P = Pass;
LowBit = getFSPassBitBegin(P);
HighBit = getFSPassBitEnd(P);
assert(LowBit < HighBit && "HighBit needs to be greater than Lowbit");
}
MIRProfileLoader(StringRef Name, StringRef RemapName)
: SampleProfileLoaderBaseImpl(std::string(Name), std::string(RemapName)) {
}
void setBranchProbs(MachineFunction &F);
bool runOnFunction(MachineFunction &F);
bool doInitialization(Module &M);
bool isValid() const { return ProfileIsValid; }
protected:
friend class SampleCoverageTracker;
/// Hold the information of the basic block frequency.
MachineBlockFrequencyInfo *BFI;
/// PassNum is the sequence number this pass is called, start from 1.
FSDiscriminatorPass P;
// LowBit in the FS discriminator used by this instance. Note the number is
// 0-based. Base discrimnator use bit 0 to bit 11.
unsigned LowBit;
// HighwBit in the FS discriminator used by this instance. Note the number
// is 0-based.
unsigned HighBit;
bool ProfileIsValid = true;
};
template <>
void SampleProfileLoaderBaseImpl<
MachineBasicBlock>::computeDominanceAndLoopInfo(MachineFunction &F) {}
void MIRProfileLoader::setBranchProbs(MachineFunction &F) {
LLVM_DEBUG(dbgs() << "\nPropagation complete. Setting branch probs\n");
for (auto &BI : F) {
MachineBasicBlock *BB = &BI;
if (BB->succ_size() < 2)
continue;
const MachineBasicBlock *EC = EquivalenceClass[BB];
uint64_t BBWeight = BlockWeights[EC];
uint64_t SumEdgeWeight = 0;
for (MachineBasicBlock *Succ : BB->successors()) {
Edge E = std::make_pair(BB, Succ);
SumEdgeWeight += EdgeWeights[E];
}
if (BBWeight != SumEdgeWeight) {
LLVM_DEBUG(dbgs() << "BBweight is not equal to SumEdgeWeight: BBWWeight="
<< BBWeight << " SumEdgeWeight= " << SumEdgeWeight
<< "\n");
BBWeight = SumEdgeWeight;
}
if (BBWeight == 0) {
LLVM_DEBUG(dbgs() << "SKIPPED. All branch weights are zero.\n");
continue;
}
#ifndef NDEBUG
uint64_t BBWeightOrig = BBWeight;
#endif
uint32_t MaxWeight = std::numeric_limits<uint32_t>::max();
uint32_t Factor = 1;
if (BBWeight > MaxWeight) {
Factor = BBWeight / MaxWeight + 1;
BBWeight /= Factor;
LLVM_DEBUG(dbgs() << "Scaling weights by " << Factor << "\n");
}
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
SE = BB->succ_end();
SI != SE; ++SI) {
MachineBasicBlock *Succ = *SI;
Edge E = std::make_pair(BB, Succ);
uint64_t EdgeWeight = EdgeWeights[E];
EdgeWeight /= Factor;
assert(BBWeight >= EdgeWeight &&
"BBweight is larger than EdgeWeight -- should not happen.\n");
BranchProbability OldProb = BFI->getMBPI()->getEdgeProbability(BB, SI);
BranchProbability NewProb(EdgeWeight, BBWeight);
if (OldProb == NewProb)
continue;
BB->setSuccProbability(SI, NewProb);
#ifndef NDEBUG
if (!ShowFSBranchProb)
continue;
bool Show = false;
BranchProbability Diff;
if (OldProb > NewProb)
Diff = OldProb - NewProb;
else
Diff = NewProb - OldProb;
Show = (Diff >= BranchProbability(FSProfileDebugProbDiffThreshold, 100));
Show &= (BBWeightOrig >= FSProfileDebugBWThreshold);
auto DIL = BB->findBranchDebugLoc();
auto SuccDIL = Succ->findBranchDebugLoc();
if (Show) {
dbgs() << "Set branch fs prob: MBB (" << BB->getNumber() << " -> "
<< Succ->getNumber() << "): ";
if (DIL)
dbgs() << DIL->getFilename() << ":" << DIL->getLine() << ":"
<< DIL->getColumn();
if (SuccDIL)
dbgs() << "-->" << SuccDIL->getFilename() << ":" << SuccDIL->getLine()
<< ":" << SuccDIL->getColumn();
dbgs() << " W=" << BBWeightOrig << " " << OldProb << " --> " << NewProb
<< "\n";
}
#endif
}
}
}
bool MIRProfileLoader::doInitialization(Module &M) {
auto &Ctx = M.getContext();
auto ReaderOrErr = sampleprof::SampleProfileReader::create(Filename, Ctx, P,
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->setModule(&M);
ProfileIsValid = (Reader->read() == sampleprof_error::success);
Reader->getSummary();
return true;
}
bool MIRProfileLoader::runOnFunction(MachineFunction &MF) {
Function &Func = MF.getFunction();
clearFunctionData(false);
Samples = Reader->getSamplesFor(Func);
if (!Samples || Samples->empty())
return false;
if (getFunctionLoc(MF) == 0)
return false;
DenseSet<GlobalValue::GUID> InlinedGUIDs;
bool Changed = computeAndPropagateWeights(MF, InlinedGUIDs);
// Set the new BPI, BFI.
setBranchProbs(MF);
return Changed;
}
} // namespace llvm
MIRProfileLoaderPass::MIRProfileLoaderPass(std::string FileName,
std::string RemappingFileName,
FSDiscriminatorPass P)
: MachineFunctionPass(ID), ProfileFileName(FileName), P(P),
MIRSampleLoader(
std::make_unique<MIRProfileLoader>(FileName, RemappingFileName)) {
LowBit = getFSPassBitBegin(P);
HighBit = getFSPassBitEnd(P);
assert(LowBit < HighBit && "HighBit needs to be greater than Lowbit");
}
bool MIRProfileLoaderPass::runOnMachineFunction(MachineFunction &MF) {
if (!MIRSampleLoader->isValid())
return false;
LLVM_DEBUG(dbgs() << "MIRProfileLoader pass working on Func: "
<< MF.getFunction().getName() << "\n");
MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
MIRSampleLoader->setInitVals(
&getAnalysis<MachineDominatorTree>(),
&getAnalysis<MachinePostDominatorTree>(), &getAnalysis<MachineLoopInfo>(),
MBFI, &getAnalysis<MachineOptimizationRemarkEmitterPass>().getORE());
MF.RenumberBlocks();
if (ViewBFIBefore && ViewBlockLayoutWithBFI != GVDT_None &&
(ViewBlockFreqFuncName.empty() ||
MF.getFunction().getName().equals(ViewBlockFreqFuncName))) {
MBFI->view("MIR_Prof_loader_b." + MF.getName(), false);
}
bool Changed = MIRSampleLoader->runOnFunction(MF);
if (Changed)
MBFI->calculate(MF, *MBFI->getMBPI(), *&getAnalysis<MachineLoopInfo>());
if (ViewBFIAfter && ViewBlockLayoutWithBFI != GVDT_None &&
(ViewBlockFreqFuncName.empty() ||
MF.getFunction().getName().equals(ViewBlockFreqFuncName))) {
MBFI->view("MIR_prof_loader_a." + MF.getName(), false);
}
return Changed;
}
bool MIRProfileLoaderPass::doInitialization(Module &M) {
LLVM_DEBUG(dbgs() << "MIRProfileLoader pass working on Module " << M.getName()
<< "\n");
MIRSampleLoader->setFSPass(P);
return MIRSampleLoader->doInitialization(M);
}
void MIRProfileLoaderPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<MachineBlockFrequencyInfo>();
AU.addRequired<MachineDominatorTree>();
AU.addRequired<MachinePostDominatorTree>();
AU.addRequiredTransitive<MachineLoopInfo>();
AU.addRequired<MachineOptimizationRemarkEmitterPass>();
MachineFunctionPass::getAnalysisUsage(AU);
}
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