tools/llvm-exegesis/lib/BenchmarkRunner.h

   1 //===-- BenchmarkRunner.h ---------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// \file
  10 /// Defines the abstract BenchmarkRunner class for measuring a certain execution
  11 /// property of instructions (e.g. latency).
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H
  16 #define LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H
  17
  18 #include "Assembler.h"
  19 #include "BenchmarkCode.h"
  20 #include "BenchmarkResult.h"
  21 #include "LlvmState.h"
  22 #include "MCInstrDescView.h"
  23 #include "llvm/MC/MCInst.h"
  24 #include "llvm/Support/Error.h"
  25 #include <cstdlib>
  26 #include <memory>
  27 #include <vector>
  28
  29 namespace llvm {
  30 namespace exegesis {
  31
  32 // A class representing failures that happened during Benchmark, they are used
  33 // to report informations to the user.
  34 class BenchmarkFailure : public llvm::StringError {
  35 public:
  36   BenchmarkFailure(const llvm::Twine &S);
  37 };
  38
  39 // Common code for all benchmark modes.
  40 class BenchmarkRunner {
  41 public:
  42   explicit BenchmarkRunner(const LLVMState &State,
  43                            InstructionBenchmark::ModeE Mode);
  44
  45   virtual ~BenchmarkRunner();
  46
  47   InstructionBenchmark runConfiguration(const BenchmarkCode &Configuration,
  48                                         unsigned NumRepetitions,
  49                                         bool DumpObjectToDisk) const;
  50
  51   // Scratch space to run instructions that touch memory.
  52   struct ScratchSpace {
  53     static constexpr const size_t kAlignment = 1024;
  54     static constexpr const size_t kSize = 1 << 20; // 1MB.
  55     ScratchSpace()
  56         : UnalignedPtr(llvm::make_unique<char[]>(kSize + kAlignment)),
  57           AlignedPtr(
  58               UnalignedPtr.get() + kAlignment -
  59               (reinterpret_cast<intptr_t>(UnalignedPtr.get()) % kAlignment)) {}
  60     char *ptr() const { return AlignedPtr; }
  61     void clear() { std::memset(ptr(), 0, kSize); }
  62
  63   private:
  64     const std::unique_ptr<char[]> UnalignedPtr;
  65     char *const AlignedPtr;
  66   };
  67
  68   // A helper to measure counters while executing a function in a sandboxed
  69   // context.
  70   class FunctionExecutor {
  71   public:
  72     virtual ~FunctionExecutor();
  73     virtual llvm::Expected<int64_t>
  74     runAndMeasure(const char *Counters) const = 0;
  75   };
  76
  77 protected:
  78   const LLVMState &State;
  79   const InstructionBenchmark::ModeE Mode;
  80
  81 private:
  82   virtual llvm::Expected<std::vector<BenchmarkMeasure>>
  83   runMeasurements(const FunctionExecutor &Executor) const = 0;
  84
  85   llvm::Expected<std::string>
  86   writeObjectFile(const BenchmarkCode &Configuration,
  87                   llvm::ArrayRef<llvm::MCInst> Code) const;
  88
  89   const std::unique_ptr<ScratchSpace> Scratch;
  90 };
  91
  92 } // namespace exegesis
  93 } // namespace llvm
  94
  95 #endif // LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H