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