tools/llvm-exegesis/lib/Uops.h

   1 //===-- Uops.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 /// A BenchmarkRunner implementation to measure uop decomposition.
  11 ///
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_UOPS_H
  15 #define LLVM_TOOLS_LLVM_EXEGESIS_UOPS_H
  16
  17 #include "BenchmarkRunner.h"
  18 #include "SnippetGenerator.h"
  19
  20 namespace llvm {
  21 namespace exegesis {
  22
  23 class UopsSnippetGenerator : public SnippetGenerator {
  24 public:
  25   using SnippetGenerator::SnippetGenerator;
  26   ~UopsSnippetGenerator() override;
  27
  28   Expected<std::vector<CodeTemplate>>
  29   generateCodeTemplates(const Instruction &Instr,
  30                         const BitVector &ForbiddenRegisters) const override;
  31
  32   static constexpr const size_t kMinNumDifferentAddresses = 6;
  33
  34 private:
  35   // Instantiates memory operands within a snippet.
  36   // To make computations as parallel as possible, we generate independant
  37   // memory locations for instructions that load and store. If there are less
  38   // than kMinNumDifferentAddresses in the original snippet, we duplicate
  39   // instructions until there are this number of instructions.
  40   // For example, assuming kMinNumDifferentAddresses=5 and
  41   // getMaxMemoryAccessSize()=64, if the original snippet is:
  42   //   mov eax, [memory]
  43   // we might generate:
  44   //   mov eax, [rdi]
  45   //   mov eax, [rdi + 64]
  46   //   mov eax, [rdi + 128]
  47   //   mov eax, [rdi + 192]
  48   //   mov eax, [rdi + 256]
  49   // If the original snippet is:
  50   //   mov eax, [memory]
  51   //   add eax, [memory]
  52   // we might generate:
  53   //   mov eax, [rdi]
  54   //   add eax, [rdi + 64]
  55   //   mov eax, [rdi + 128]
  56   //   add eax, [rdi + 192]
  57   //   mov eax, [rdi + 256]
  58   void instantiateMemoryOperands(
  59       unsigned ScratchSpaceReg,
  60       std::vector<InstructionTemplate> &SnippetTemplate) const;
  61 };
  62
  63 class UopsBenchmarkRunner : public BenchmarkRunner {
  64 public:
  65   UopsBenchmarkRunner(const LLVMState &State)
  66       : BenchmarkRunner(State, InstructionBenchmark::Uops) {}
  67   ~UopsBenchmarkRunner() override;
  68
  69   static constexpr const size_t kMinNumDifferentAddresses = 6;
  70
  71 private:
  72   Expected<std::vector<BenchmarkMeasure>>
  73   runMeasurements(const FunctionExecutor &Executor) const override;
  74 };
  75
  76 } // namespace exegesis
  77 } // namespace llvm
  78
  79 #endif // LLVM_TOOLS_LLVM_EXEGESIS_UOPS_H