llvm/tools/llvm-exegesis/lib/BenchmarkResult.h

   1 //===-- BenchmarkResult.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 classes to represent measurements and serialize/deserialize them to
  11 //  Yaml.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRESULT_H
  16 #define LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRESULT_H
  17
  18 #include "LlvmState.h"
  19 #include "RegisterValue.h"
  20 #include "llvm/ADT/StringRef.h"
  21 #include "llvm/MC/MCInst.h"
  22 #include "llvm/MC/MCInstBuilder.h"
  23 #include "llvm/Support/YAMLTraits.h"
  24 #include <limits>
  25 #include <set>
  26 #include <string>
  27 #include <unordered_map>
  28 #include <vector>
  29
  30 namespace llvm {
  31 class Error;
  32
  33 namespace exegesis {
  34
  35 enum class BenchmarkPhaseSelectorE {
  36   PrepareSnippet,
  37   PrepareAndAssembleSnippet,
  38   AssembleMeasuredCode,
  39   Measure,
  40 };
  41
  42 enum class BenchmarkFilter { All, RegOnly, WithMem };
  43
  44 struct MemoryValue {
  45   // The arbitrary bit width constant that defines the value.
  46   APInt Value;
  47   // The size of the value in bytes.
  48   size_t SizeBytes;
  49   // The index of the memory value.
  50   size_t Index;
  51 };
  52
  53 struct MemoryMapping {
  54   // The address to place the mapping at.
  55   intptr_t Address;
  56   // The name of the value that should be mapped.
  57   std::string MemoryValueName;
  58 };
  59
  60 struct BenchmarkKey {
  61   // The LLVM opcode name.
  62   std::vector<MCInst> Instructions;
  63   // The initial values of the registers.
  64   std::vector<RegisterValue> RegisterInitialValues;
  65   // The memory values that can be mapped into the execution context of the
  66   // snippet.
  67   std::unordered_map<std::string, MemoryValue> MemoryValues;
  68   // The memory mappings that the snippet can access.
  69   std::vector<MemoryMapping> MemoryMappings;
  70   // An opaque configuration, that can be used to separate several benchmarks of
  71   // the same instruction under different configurations.
  72   std::string Config;
  73 };
  74
  75 struct BenchmarkMeasure {
  76   // A helper to create an unscaled BenchmarkMeasure.
  77   static BenchmarkMeasure Create(std::string Key, double Value) {
  78     return {Key, Value, Value};
  79   }
  80   std::string Key;
  81   // This is the per-instruction value, i.e. measured quantity scaled per
  82   // instruction.
  83   double PerInstructionValue;
  84   // This is the per-snippet value, i.e. measured quantity for one repetition of
  85   // the whole snippet.
  86   double PerSnippetValue;
  87 };
  88
  89 // The result of an instruction benchmark.
  90 struct Benchmark {
  91   BenchmarkKey Key;
  92   enum ModeE { Unknown, Latency, Uops, InverseThroughput };
  93   ModeE Mode;
  94   std::string CpuName;
  95   std::string LLVMTriple;
  96   // Which instruction is being benchmarked here?
  97   const MCInst &keyInstruction() const { return Key.Instructions[0]; }
  98   // The number of instructions inside the repeated snippet. For example, if a
  99   // snippet of 3 instructions is repeated 4 times, this is 12.
 100   unsigned NumRepetitions = 0;
 101   enum RepetitionModeE { Duplicate, Loop, AggregateMin };
 102   // Note that measurements are per instruction.
 103   std::vector<BenchmarkMeasure> Measurements;
 104   std::string Error;
 105   std::string Info;
 106   std::vector<uint8_t> AssembledSnippet;
 107   // How to aggregate measurements.
 108   enum ResultAggregationModeE { Min, Max, Mean, MinVariance };
 109
 110   Benchmark() = default;
 111   Benchmark(Benchmark &&) = default;
 112
 113   Benchmark(const Benchmark &) = delete;
 114   Benchmark &operator=(const Benchmark &) = delete;
 115   Benchmark &operator=(Benchmark &&) = delete;
 116
 117   // Read functions.
 118   static Expected<Benchmark> readYaml(const LLVMState &State,
 119                                                  MemoryBufferRef Buffer);
 120
 121   static Expected<std::vector<Benchmark>>
 122   readYamls(const LLVMState &State, MemoryBufferRef Buffer);
 123
 124   // Given a set of serialized instruction benchmarks, returns the set of
 125   // triples and CPUs that appear in the list of benchmarks.
 126   struct TripleAndCpu {
 127     std::string LLVMTriple;
 128     std::string CpuName;
 129     bool operator<(const TripleAndCpu &O) const {
 130       return std::tie(LLVMTriple, CpuName) < std::tie(O.LLVMTriple, O.CpuName);
 131     }
 132   };
 133   static Expected<std::set<TripleAndCpu>>
 134   readTriplesAndCpusFromYamls(MemoryBufferRef Buffer);
 135
 136   class Error readYamlFrom(const LLVMState &State, StringRef InputContent);
 137
 138   // Write functions, non-const because of YAML traits.
 139   // NOTE: we intentionally do *NOT* have a variant of this function taking
 140   //       filename, because it's behaviour is bugprone with regards to
 141   //       accidentally using it more than once and overriding previous YAML.
 142   class Error writeYamlTo(const LLVMState &State, raw_ostream &S);
 143 };
 144
 145 bool operator==(const BenchmarkMeasure &A, const BenchmarkMeasure &B);
 146
 147 //------------------------------------------------------------------------------
 148 // Utilities to work with Benchmark measures.
 149
 150 // A class that measures stats over benchmark measures.
 151 class PerInstructionStats {
 152 public:
 153   void push(const BenchmarkMeasure &BM);
 154
 155   double avg() const {
 156     assert(NumValues);
 157     return SumValues / NumValues;
 158   }
 159   double min() const { return MinValue; }
 160   double max() const { return MaxValue; }
 161
 162   const std::string &key() const { return Key; }
 163
 164 private:
 165   std::string Key;
 166   double SumValues = 0.0;
 167   int NumValues = 0;
 168   double MaxValue = std::numeric_limits<double>::min();
 169   double MinValue = std::numeric_limits<double>::max();
 170 };
 171
 172 } // namespace exegesis
 173 } // namespace llvm
 174
 175 #endif // LLVM_TOOLS_LLVM_EXEGESIS_BENCHMARKRESULT_H