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//===-- BenchmarkRunner.h ---------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Defines the abstract BenchmarkRunner class for measuring a certain execution
/// property of instructions (e.g. latency).
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H
#define LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H
#include "Assembler.h"
#include "BenchmarkResult.h"
#include "LlvmState.h"
#include "MCInstrDescView.h"
#include "RegisterAliasing.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/Error.h"
#include <cstdlib>
#include <memory>
#include <vector>
namespace exegesis {
// A class representing failures that happened during Benchmark, they are used
// to report informations to the user.
class BenchmarkFailure : public llvm::StringError {
public:
BenchmarkFailure(const llvm::Twine &S);
};
// A collection of instructions that are to be assembled, executed and measured.
struct BenchmarkCode {
// The sequence of instructions that are to be repeated.
std::vector<llvm::MCInst> Instructions;
// Before the code is executed some instructions are added to setup the
// registers initial values.
std::vector<unsigned> RegsToDef;
// We also need to provide the registers that are live on entry for the
// assembler to generate proper prologue/epilogue.
std::vector<unsigned> LiveIns;
// Informations about how this configuration was built.
std::string Info;
};
// Common code for all benchmark modes.
class BenchmarkRunner {
public:
explicit BenchmarkRunner(const LLVMState &State,
InstructionBenchmark::ModeE Mode);
virtual ~BenchmarkRunner();
llvm::Expected<std::vector<InstructionBenchmark>>
run(unsigned Opcode, unsigned NumRepetitions);
// Given a snippet, computes which registers the setup code needs to define.
std::vector<unsigned>
computeRegsToDef(const std::vector<InstructionBuilder> &Snippet) const;
// Scratch space to run instructions that touch memory.
struct ScratchSpace {
static constexpr const size_t kAlignment = 1024;
static constexpr const size_t kSize = 1 << 20; // 1MB.
ScratchSpace()
: UnalignedPtr(llvm::make_unique<char[]>(kSize + kAlignment)),
AlignedPtr(
UnalignedPtr.get() + kAlignment -
(reinterpret_cast<intptr_t>(UnalignedPtr.get()) % kAlignment)) {}
char *ptr() const { return AlignedPtr; }
void clear() { std::memset(ptr(), 0, kSize); }
private:
const std::unique_ptr<char[]> UnalignedPtr;
char *const AlignedPtr;
};
protected:
const LLVMState &State;
const RegisterAliasingTrackerCache RATC;
// Generates a single code template that has a self-dependency.
llvm::Expected<CodeTemplate>
generateSelfAliasingCodeTemplate(const Instruction &Instr) const;
// Generates a single code template without assignment constraints.
llvm::Expected<CodeTemplate>
generateUnconstrainedCodeTemplate(const Instruction &Instr,
llvm::StringRef Msg) const;
private:
// API to be implemented by subclasses.
virtual llvm::Expected<CodeTemplate>
generateCodeTemplate(unsigned Opcode) const = 0;
virtual std::vector<BenchmarkMeasure>
runMeasurements(const ExecutableFunction &EF, ScratchSpace &Scratch,
const unsigned NumRepetitions) const = 0;
// Internal helpers.
InstructionBenchmark runConfiguration(const BenchmarkCode &Configuration,
unsigned NumRepetitions) const;
// Calls generateCodeTemplate and expands it into one or more BenchmarkCode.
llvm::Expected<std::vector<BenchmarkCode>>
generateConfigurations(unsigned Opcode) const;
llvm::Expected<std::string>
writeObjectFile(const BenchmarkCode &Configuration,
llvm::ArrayRef<llvm::MCInst> Code) const;
const InstructionBenchmark::ModeE Mode;
const std::unique_ptr<ScratchSpace> Scratch;
};
} // namespace exegesis
#endif // LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H
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