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 "SnippetRepetitor.h"
  24 #include "llvm/MC/MCInst.h"
  25 #include "llvm/Support/Error.h"
  26 #include <cstdlib>
  27 #include <memory>
  28 #include <vector>
  29
  30 namespace llvm {
  31 namespace exegesis {
  32
  33 // A class representing failures that happened during Benchmark, they are used
  34 // to report informations to the user.
  35 class BenchmarkFailure : public llvm::StringError {
  36 public:
  37   BenchmarkFailure(const llvm::Twine &S);
  38 };
  39
  40 // Common code for all benchmark modes.
  41 class BenchmarkRunner {
  42 public:
  43   explicit BenchmarkRunner(const LLVMState &State,
  44                            InstructionBenchmark::ModeE Mode);
  45
  46   virtual ~BenchmarkRunner();
  47
  48   InstructionBenchmark runConfiguration(const BenchmarkCode &Configuration,
  49                                         unsigned NumRepetitions,
  50                                         const SnippetRepetitor &Repetitor,
  51                                         bool DumpObjectToDisk) const;
  52
  53   // Scratch space to run instructions that touch memory.
  54   struct ScratchSpace {
  55     static constexpr const size_t kAlignment = 1024;
  56     static constexpr const size_t kSize = 1 << 20; // 1MB.
  57     ScratchSpace()
  58         : UnalignedPtr(std::make_unique<char[]>(kSize + kAlignment)),
  59           AlignedPtr(
  60               UnalignedPtr.get() + kAlignment -
  61               (reinterpret_cast<intptr_t>(UnalignedPtr.get()) % kAlignment)) {}
  62     char *ptr() const { return AlignedPtr; }
  63     void clear() { std::memset(ptr(), 0, kSize); }
  64
  65   private:
  66     const std::unique_ptr<char[]> UnalignedPtr;
  67     char *const AlignedPtr;
  68   };
  69
  70   // A helper to measure counters while executing a function in a sandboxed
  71   // context.
  72   class FunctionExecutor {
  73   public:
  74     virtual ~FunctionExecutor();
  75     virtual llvm::Expected<int64_t>
  76     runAndMeasure(const char *Counters) const = 0;
  77   };
  78
  79 protected:
  80   const LLVMState &State;
  81   const InstructionBenchmark::ModeE Mode;
  82
  83 private:
  84   virtual llvm::Expected<std::vector<BenchmarkMeasure>>
  85   runMeasurements(const FunctionExecutor &Executor) const = 0;
  86
  87   llvm::Expected<std::string>
  88   writeObjectFile(const BenchmarkCode &Configuration,
  89                   const FillFunction &Fill) const;
  90
  91   const std::unique_ptr<ScratchSpace> Scratch;
  92 };
  93
  94 } // namespace exegesis
  95 } // namespace llvm
  96
  97 #endif // LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H