tools/llvm-exegesis/lib/CodeTemplate.h

   1 //===-- CodeTemplate.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 set of structures and functions to craft instructions for the
  12 /// SnippetGenerator.
  13 ///
  14 //===----------------------------------------------------------------------===//
  15
  16 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_CODETEMPLATE_H
  17 #define LLVM_TOOLS_LLVM_EXEGESIS_CODETEMPLATE_H
  18
  19 #include "MCInstrDescView.h"
  20
  21 namespace exegesis {
  22
  23 // A template for an Instruction holding values for each of its Variables.
  24 struct InstructionTemplate {
  25   InstructionTemplate(const Instruction &Instr);
  26
  27   InstructionTemplate(const InstructionTemplate &);            // default
  28   InstructionTemplate &operator=(const InstructionTemplate &); // default
  29   InstructionTemplate(InstructionTemplate &&);                 // default
  30   InstructionTemplate &operator=(InstructionTemplate &&);      // default
  31
  32   unsigned getOpcode() const;
  33   llvm::MCOperand &getValueFor(const Variable &Var);
  34   const llvm::MCOperand &getValueFor(const Variable &Var) const;
  35   llvm::MCOperand &getValueFor(const Operand &Op);
  36   const llvm::MCOperand &getValueFor(const Operand &Op) const;
  37   bool hasImmediateVariables() const;
  38
  39   // Assigns a Random Value to all Variables that are still Invalid.
  40   // Do not use any of the registers in `ForbiddenRegs`.
  41   void randomizeUnsetVariables(const llvm::BitVector &ForbiddenRegs);
  42
  43   // Builds an llvm::MCInst from this InstructionTemplate setting its operands
  44   // to the corresponding variable values. Precondition: All VariableValues must
  45   // be set.
  46   llvm::MCInst build() const;
  47
  48   Instruction Instr;
  49   llvm::SmallVector<llvm::MCOperand, 4> VariableValues;
  50 };
  51
  52 // A CodeTemplate is a set of InstructionTemplates that may not be fully
  53 // specified (i.e. some variables are not yet set). This allows the
  54 // BenchmarkRunner to instantiate it many times with specific values to study
  55 // their impact on instruction's performance.
  56 struct CodeTemplate {
  57   CodeTemplate() = default;
  58
  59   CodeTemplate(CodeTemplate &&);            // default
  60   CodeTemplate &operator=(CodeTemplate &&); // default
  61   CodeTemplate(const CodeTemplate &) = delete;
  62   CodeTemplate &operator=(const CodeTemplate &) = delete;
  63
  64   // Some information about how this template has been created.
  65   std::string Info;
  66   // The list of the instructions for this template.
  67   std::vector<InstructionTemplate> Instructions;
  68   // If the template uses the provided scratch memory, the register in which
  69   // the pointer to this memory is passed in to the function.
  70   unsigned ScratchSpacePointerInReg = 0;
  71 };
  72
  73 // A global Random Number Generator to randomize configurations.
  74 // FIXME: Move random number generation into an object and make it seedable for
  75 // unit tests.
  76 std::mt19937 &randomGenerator();
  77
  78 // Picks a random bit among the bits set in Vector and returns its index.
  79 // Precondition: Vector must have at least one bit set.
  80 size_t randomBit(const llvm::BitVector &Vector);
  81
  82 // Picks a random configuration, then selects a random def and a random use from
  83 // it and finally set the selected values in the provided InstructionInstances.
  84 void setRandomAliasing(const AliasingConfigurations &AliasingConfigurations,
  85                        InstructionTemplate &DefIB, InstructionTemplate &UseIB);
  86
  87 } // namespace exegesis
  88
  89 #endif // LLVM_TOOLS_LLVM_EXEGESIS_CODETEMPLATE_H