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//===-- BenchmarkRunner.cpp -------------------------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include <array>
#include <string>
#include "Assembler.h"
#include "BenchmarkRunner.h"
#include "Error.h"
#include "MCInstrDescView.h"
#include "PerfHelper.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/CrashRecoveryContext.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Program.h"
namespace llvm {
namespace exegesis {
BenchmarkRunner::BenchmarkRunner(const LLVMState &State,
InstructionBenchmark::ModeE Mode)
: State(State), Mode(Mode), Scratch(std::make_unique<ScratchSpace>()) {}
BenchmarkRunner::~BenchmarkRunner() = default;
namespace {
class FunctionExecutorImpl : public BenchmarkRunner::FunctionExecutor {
public:
FunctionExecutorImpl(const LLVMState &State,
object::OwningBinary<object::ObjectFile> Obj,
BenchmarkRunner::ScratchSpace *Scratch)
: Function(State.createTargetMachine(), std::move(Obj)),
Scratch(Scratch) {}
private:
Expected<int64_t> runAndMeasure(const char *Counters) const override {
// We sum counts when there are several counters for a single ProcRes
// (e.g. P23 on SandyBridge).
int64_t CounterValue = 0;
SmallVector<StringRef, 2> CounterNames;
StringRef(Counters).split(CounterNames, '+');
char *const ScratchPtr = Scratch->ptr();
for (auto &CounterName : CounterNames) {
CounterName = CounterName.trim();
pfm::PerfEvent PerfEvent(CounterName);
if (!PerfEvent.valid())
report_fatal_error(
Twine("invalid perf event '").concat(CounterName).concat("'"));
pfm::Counter Counter(PerfEvent);
Scratch->clear();
{
CrashRecoveryContext CRC;
CrashRecoveryContext::Enable();
const bool Crashed = !CRC.RunSafely([this, &Counter, ScratchPtr]() {
Counter.start();
this->Function(ScratchPtr);
Counter.stop();
});
CrashRecoveryContext::Disable();
// FIXME: Better diagnosis.
if (Crashed)
return make_error<Failure>("snippet crashed while running");
}
CounterValue += Counter.read();
}
return CounterValue;
}
const ExecutableFunction Function;
BenchmarkRunner::ScratchSpace *const Scratch;
};
} // namespace
InstructionBenchmark BenchmarkRunner::runConfiguration(
const BenchmarkCode &BC, unsigned NumRepetitions,
const SnippetRepetitor &Repetitor, bool DumpObjectToDisk) const {
InstructionBenchmark InstrBenchmark;
InstrBenchmark.Mode = Mode;
InstrBenchmark.CpuName = State.getTargetMachine().getTargetCPU();
InstrBenchmark.LLVMTriple =
State.getTargetMachine().getTargetTriple().normalize();
InstrBenchmark.NumRepetitions = NumRepetitions;
InstrBenchmark.Info = BC.Info;
const std::vector<MCInst> &Instructions = BC.Key.Instructions;
InstrBenchmark.Key = BC.Key;
// Assemble at least kMinInstructionsForSnippet instructions by repeating the
// snippet for debug/analysis. This is so that the user clearly understands
// that the inside instructions are repeated.
constexpr const int kMinInstructionsForSnippet = 16;
{
SmallString<0> Buffer;
raw_svector_ostream OS(Buffer);
assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
BC.LiveIns, BC.Key.RegisterInitialValues,
Repetitor.Repeat(Instructions, kMinInstructionsForSnippet),
OS);
const ExecutableFunction EF(State.createTargetMachine(),
getObjectFromBuffer(OS.str()));
const auto FnBytes = EF.getFunctionBytes();
InstrBenchmark.AssembledSnippet.assign(FnBytes.begin(), FnBytes.end());
}
// Assemble NumRepetitions instructions repetitions of the snippet for
// measurements.
const auto Filler =
Repetitor.Repeat(Instructions, InstrBenchmark.NumRepetitions);
object::OwningBinary<object::ObjectFile> ObjectFile;
if (DumpObjectToDisk) {
auto ObjectFilePath = writeObjectFile(BC, Filler);
if (Error E = ObjectFilePath.takeError()) {
InstrBenchmark.Error = toString(std::move(E));
return InstrBenchmark;
}
outs() << "Check generated assembly with: /usr/bin/objdump -d "
<< *ObjectFilePath << "\n";
ObjectFile = getObjectFromFile(*ObjectFilePath);
} else {
SmallString<0> Buffer;
raw_svector_ostream OS(Buffer);
assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
BC.LiveIns, BC.Key.RegisterInitialValues, Filler, OS);
ObjectFile = getObjectFromBuffer(OS.str());
}
const FunctionExecutorImpl Executor(State, std::move(ObjectFile),
Scratch.get());
auto Measurements = runMeasurements(Executor);
if (Error E = Measurements.takeError()) {
InstrBenchmark.Error = toString(std::move(E));
return InstrBenchmark;
}
InstrBenchmark.Measurements = std::move(*Measurements);
assert(InstrBenchmark.NumRepetitions > 0 && "invalid NumRepetitions");
for (BenchmarkMeasure &BM : InstrBenchmark.Measurements) {
// Scale the measurements by instruction.
BM.PerInstructionValue /= InstrBenchmark.NumRepetitions;
// Scale the measurements by snippet.
BM.PerSnippetValue *= static_cast<double>(Instructions.size()) /
InstrBenchmark.NumRepetitions;
}
return InstrBenchmark;
}
Expected<std::string>
BenchmarkRunner::writeObjectFile(const BenchmarkCode &BC,
const FillFunction &FillFunction) const {
int ResultFD = 0;
SmallString<256> ResultPath;
if (Error E = errorCodeToError(
sys::fs::createTemporaryFile("snippet", "o", ResultFD, ResultPath)))
return std::move(E);
raw_fd_ostream OFS(ResultFD, true /*ShouldClose*/);
assembleToStream(State.getExegesisTarget(), State.createTargetMachine(),
BC.LiveIns, BC.Key.RegisterInitialValues, FillFunction, OFS);
return ResultPath.str();
}
BenchmarkRunner::FunctionExecutor::~FunctionExecutor() {}
} // namespace exegesis
} // namespace llvm
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