llvm/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/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   enum ExecutionModeE { InProcess, SubProcess };
  38
  39   explicit BenchmarkRunner(const LLVMState &State, Benchmark::ModeE Mode,
  40                            BenchmarkPhaseSelectorE BenchmarkPhaseSelector,
  41                            ExecutionModeE ExecutionMode);
  42
  43   virtual ~BenchmarkRunner();
  44
  45   class RunnableConfiguration {
  46     friend class BenchmarkRunner;
  47
  48   public:
  49     ~RunnableConfiguration() = default;
  50     RunnableConfiguration(RunnableConfiguration &&) = default;
  51
  52     RunnableConfiguration(const RunnableConfiguration &) = delete;
  53     RunnableConfiguration &operator=(RunnableConfiguration &&) = delete;
  54     RunnableConfiguration &operator=(const RunnableConfiguration &) = delete;
  55
  56   private:
  57     RunnableConfiguration() = default;
  58
  59     Benchmark InstrBenchmark;
  60     object::OwningBinary<object::ObjectFile> ObjectFile;
  61   };
  62
  63   Expected<RunnableConfiguration>
  64   getRunnableConfiguration(const BenchmarkCode &Configuration,
  65                            unsigned NumRepetitions, unsigned LoopUnrollFactor,
  66                            const SnippetRepetitor &Repetitor) const;
  67
  68   std::pair<Error, Benchmark>
  69   runConfiguration(RunnableConfiguration &&RC,
  70                    const std::optional<StringRef> &DumpFile) const;
  71
  72   // Scratch space to run instructions that touch memory.
  73   struct ScratchSpace {
  74     static constexpr const size_t kAlignment = 1024;
  75     static constexpr const size_t kSize = 1 << 20; // 1MB.
  76     ScratchSpace()
  77         : UnalignedPtr(std::make_unique<char[]>(kSize + kAlignment)),
  78           AlignedPtr(
  79               UnalignedPtr.get() + kAlignment -
  80               (reinterpret_cast<intptr_t>(UnalignedPtr.get()) % kAlignment)) {}
  81     char *ptr() const { return AlignedPtr; }
  82     void clear() { std::memset(ptr(), 0, kSize); }
  83
  84   private:
  85     const std::unique_ptr<char[]> UnalignedPtr;
  86     char *const AlignedPtr;
  87   };
  88
  89   // A helper to measure counters while executing a function in a sandboxed
  90   // context.
  91   class FunctionExecutor {
  92   public:
  93     virtual ~FunctionExecutor();
  94
  95     Expected<llvm::SmallVector<int64_t, 4>>
  96     runAndSample(const char *Counters) const;
  97
  98   protected:
  99     static void
 100     accumulateCounterValues(const llvm::SmallVectorImpl<int64_t> &NewValues,
 101                             llvm::SmallVectorImpl<int64_t> *Result);
 102     virtual Expected<llvm::SmallVector<int64_t, 4>>
 103     runWithCounter(StringRef CounterName) const = 0;
 104   };
 105
 106 protected:
 107   const LLVMState &State;
 108   const Benchmark::ModeE Mode;
 109   const BenchmarkPhaseSelectorE BenchmarkPhaseSelector;
 110   const ExecutionModeE ExecutionMode;
 111
 112 private:
 113   virtual Expected<std::vector<BenchmarkMeasure>>
 114   runMeasurements(const FunctionExecutor &Executor) const = 0;
 115
 116   Expected<SmallString<0>>
 117   assembleSnippet(const BenchmarkCode &BC, const SnippetRepetitor &Repetitor,
 118                   unsigned MinInstructions, unsigned LoopBodySize,
 119                   bool GenerateMemoryInstructions) const;
 120
 121   Expected<std::string> writeObjectFile(StringRef Buffer,
 122                                         StringRef FileName) const;
 123
 124   const std::unique_ptr<ScratchSpace> Scratch;
 125
 126   Expected<std::unique_ptr<FunctionExecutor>>
 127   createFunctionExecutor(object::OwningBinary<object::ObjectFile> Obj,
 128                          const BenchmarkKey &Key) const;
 129 };
 130
 131 } // namespace exegesis
 132 } // namespace llvm
 133
 134 #endif // LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRUNNER_H