tools/llvm-exegesis/lib/Uops.h

   1 //===-- Uops.h --------------------------------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 ///
  10 /// \file
  11 /// A BenchmarkRunner implementation to measure uop decomposition.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_UOPS_H
  16 #define LLVM_TOOLS_LLVM_EXEGESIS_UOPS_H
  17
  18 #include "BenchmarkRunner.h"
  19
  20 namespace exegesis {
  21
  22 class UopsBenchmarkRunner : public BenchmarkRunner {
  23 public:
  24   UopsBenchmarkRunner(const LLVMState &State)
  25       : BenchmarkRunner(State, InstructionBenchmark::Uops) {}
  26   ~UopsBenchmarkRunner() override;
  27
  28   llvm::Expected<SnippetPrototype>
  29   generatePrototype(unsigned Opcode) const override;
  30
  31   static constexpr const size_t kMinNumDifferentAddresses = 6;
  32
  33 private:
  34   llvm::Error isInfeasible(const llvm::MCInstrDesc &MCInstrDesc) const;
  35
  36   std::vector<BenchmarkMeasure>
  37   runMeasurements(const ExecutableFunction &EF, ScratchSpace &Scratch,
  38                   const unsigned NumRepetitions) const override;
  39
  40   // Instantiates memory operands within a snippet.
  41   // To make computations as parallel as possible, we generate independant
  42   // memory locations for instructions that load and store. If there are less
  43   // than kMinNumDifferentAddresses in the original snippet, we duplicate
  44   // instructions until there are this number of instructions.
  45   // For example, assuming kMinNumDifferentAddresses=5 and
  46   // getMaxMemoryAccessSize()=64, if the original snippet is:
  47   //   mov eax, [memory]
  48   // we might generate:
  49   //   mov eax, [rdi]
  50   //   mov eax, [rdi + 64]
  51   //   mov eax, [rdi + 128]
  52   //   mov eax, [rdi + 192]
  53   //   mov eax, [rdi + 256]
  54   // If the original snippet is:
  55   //   mov eax, [memory]
  56   //   add eax, [memory]
  57   // we might generate:
  58   //   mov eax, [rdi]
  59   //   add eax, [rdi + 64]
  60   //   mov eax, [rdi + 128]
  61   //   add eax, [rdi + 192]
  62   //   mov eax, [rdi + 256]
  63   void
  64   instantiateMemoryOperands(unsigned ScratchSpaceReg,
  65                             std::vector<InstructionInstance> &Snippet) const;
  66 };
  67
  68 } // namespace exegesis
  69
  70 #endif // LLVM_TOOLS_LLVM_EXEGESIS_UOPS_H