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      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/ADT/SmallVector.h"
     25 #include "llvm/MC/MCInst.h"
     26 #include "llvm/Support/Error.h"
     27 #include <cstdlib>
     28 #include <memory>
     29 #include <vector>
     30 
     31 namespace llvm {
     32 namespace exegesis {
     33 
     34 // Common code for all benchmark modes.
     35 class BenchmarkRunner {
     36 public:
     37   explicit BenchmarkRunner(const LLVMState &State,
     38                            InstructionBenchmark::ModeE Mode);
     39 
     40   virtual ~BenchmarkRunner();
     41 
     42   Expected<InstructionBenchmark>
     43   runConfiguration(const BenchmarkCode &Configuration, unsigned NumRepetitions,
     44                    ArrayRef<std::unique_ptr<const SnippetRepetitor>> Repetitors,
     45                    bool DumpObjectToDisk) const;
     46 
     47   // Scratch space to run instructions that touch memory.
     48   struct ScratchSpace {
     49     static constexpr const size_t kAlignment = 1024;
     50     static constexpr const size_t kSize = 1 << 20; // 1MB.
     51     ScratchSpace()
     52         : UnalignedPtr(std::make_unique<char[]>(kSize + kAlignment)),
     53           AlignedPtr(
     54               UnalignedPtr.get() + kAlignment -
     55               (reinterpret_cast<intptr_t>(UnalignedPtr.get()) % kAlignment)) {}
     56     char *ptr() const { return AlignedPtr; }
     57     void clear() { std::memset(ptr(), 0, kSize); }
     58 
     59   private:
     60     const std::unique_ptr<char[]> UnalignedPtr;
     61     char *const AlignedPtr;
     62   };
     63 
     64   // A helper to measure counters while executing a function in a sandboxed
     65   // context.
     66   class FunctionExecutor {
     67   public:
     68     virtual ~FunctionExecutor();
     69     // FIXME deprecate this.
     70     virtual Expected<int64_t> runAndMeasure(const char *Counters) const = 0;
     71 
     72     virtual Expected<llvm::SmallVector<int64_t, 4>>
     73     runAndSample(const char *Counters) const = 0;
     74   };
     75 
     76 protected:
     77   const LLVMState &State;
     78   const InstructionBenchmark::ModeE Mode;
     79 
     80 private:
     81   virtual Expected<std::vector<BenchmarkMeasure>>
     82   runMeasurements(const FunctionExecutor &Executor) const = 0;
     83 
     84   Expected<std::string> writeObjectFile(const BenchmarkCode &Configuration,
     85                                         const FillFunction &Fill) const;
     86 
     87   const std::unique_ptr<ScratchSpace> Scratch;
     88 };
     89 
     90 } // namespace exegesis
     91 } // namespace llvm
     92 
     93 #endif // LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H
     94