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

   1 //===-- CodeTemplate.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 set of structures and functions to craft instructions for the
  11 /// SnippetGenerator.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_CODETEMPLATE_H
  16 #define LLVM_TOOLS_LLVM_EXEGESIS_CODETEMPLATE_H
  17
  18 #include "MCInstrDescView.h"
  19 #include "llvm/ADT/BitmaskEnum.h"
  20
  21 namespace llvm {
  22 namespace exegesis {
  23
  24 // A template for an Instruction holding values for each of its Variables.
  25 struct InstructionTemplate {
  26   InstructionTemplate(const Instruction *Instr);
  27
  28   InstructionTemplate(const InstructionTemplate &);            // default
  29   InstructionTemplate &operator=(const InstructionTemplate &); // default
  30   InstructionTemplate(InstructionTemplate &&);                 // default
  31   InstructionTemplate &operator=(InstructionTemplate &&);      // default
  32
  33   unsigned getOpcode() const;
  34   MCOperand &getValueFor(const Variable &Var);
  35   const MCOperand &getValueFor(const Variable &Var) const;
  36   MCOperand &getValueFor(const Operand &Op);
  37   const MCOperand &getValueFor(const Operand &Op) const;
  38   bool hasImmediateVariables() const;
  39   const Instruction &getInstr() const { return *Instr; }
  40   ArrayRef<MCOperand> getVariableValues() const { return VariableValues; }
  41   void setVariableValues(ArrayRef<MCOperand> NewVariableValues) {
  42     assert(VariableValues.size() == NewVariableValues.size() &&
  43            "Value count mismatch");
  44     VariableValues.assign(NewVariableValues.begin(), NewVariableValues.end());
  45   }
  46
  47   // Builds an MCInst from this InstructionTemplate setting its operands
  48   // to the corresponding variable values. Precondition: All VariableValues must
  49   // be set.
  50   MCInst build() const;
  51
  52 private:
  53   const Instruction *Instr;
  54   SmallVector<MCOperand, 4> VariableValues;
  55 };
  56
  57 enum class ExecutionMode : uint8_t {
  58   UNKNOWN = 0U,
  59   // The instruction is always serial because implicit Use and Def alias.
  60   // e.g. AAA (alias via EFLAGS)
  61   ALWAYS_SERIAL_IMPLICIT_REGS_ALIAS = 1u << 0,
  62
  63   // The instruction is always serial because one Def is tied to a Use.
  64   // e.g. AND32ri (alias via tied GR32)
  65   ALWAYS_SERIAL_TIED_REGS_ALIAS = 1u << 1,
  66
  67   // The execution can be made serial by inserting a second instruction that
  68   // clobbers/reads memory.
  69   // e.g. MOV8rm
  70   SERIAL_VIA_MEMORY_INSTR = 1u << 2,
  71
  72   // The execution can be made serial by picking one Def that aliases with one
  73   // Use.
  74   // e.g. VXORPSrr XMM1, XMM1, XMM2
  75   SERIAL_VIA_EXPLICIT_REGS = 1u << 3,
  76
  77   // The execution can be made serial by inserting a second instruction that
  78   // uses one of the Defs and defs one of the Uses.
  79   // e.g.
  80   // 1st instruction: MMX_PMOVMSKBrr ECX, MM7
  81   // 2nd instruction: MMX_MOVD64rr MM7, ECX
  82   //  or instruction: MMX_MOVD64to64rr MM7, ECX
  83   //  or instruction: MMX_PINSRWrr MM7, MM7, ECX, 1
  84   SERIAL_VIA_NON_MEMORY_INSTR = 1u << 4,
  85
  86   // The execution is always parallel because the instruction is missing Use or
  87   // Def operands.
  88   ALWAYS_PARALLEL_MISSING_USE_OR_DEF = 1u << 5,
  89
  90   // The execution can be made parallel by repeating the same instruction but
  91   // making sure that Defs of one instruction do not alias with Uses of the
  92   // second one.
  93   PARALLEL_VIA_EXPLICIT_REGS = 1u << 6,
  94
  95   LLVM_MARK_AS_BITMASK_ENUM(/*Largest*/ PARALLEL_VIA_EXPLICIT_REGS)
  96 };
  97
  98 // Returns whether Execution is one of the values defined in the enum above.
  99 bool isEnumValue(ExecutionMode Execution);
 100
 101 // Returns a human readable string for the enum.
 102 StringRef getName(ExecutionMode Execution);
 103
 104 // Returns a sequence of increasing powers of two corresponding to all the
 105 // Execution flags.
 106 ArrayRef<ExecutionMode> getAllExecutionBits();
 107
 108 // Decomposes Execution into individual set bits.
 109 SmallVector<ExecutionMode, 4> getExecutionModeBits(ExecutionMode);
 110
 111 LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
 112
 113 // A CodeTemplate is a set of InstructionTemplates that may not be fully
 114 // specified (i.e. some variables are not yet set). This allows the
 115 // SnippetGenerator to instantiate it many times with specific values to study
 116 // their impact on instruction's performance.
 117 struct CodeTemplate {
 118   CodeTemplate() = default;
 119
 120   CodeTemplate(CodeTemplate &&);            // default
 121   CodeTemplate &operator=(CodeTemplate &&); // default
 122
 123   CodeTemplate clone() const;
 124
 125   ExecutionMode Execution = ExecutionMode::UNKNOWN;
 126   // See BenchmarkKey.::Config.
 127   std::string Config;
 128   // Some information about how this template has been created.
 129   std::string Info;
 130   // The list of the instructions for this template.
 131   std::vector<InstructionTemplate> Instructions;
 132   // If the template uses the provided scratch memory, the register in which
 133   // the pointer to this memory is passed in to the function.
 134   unsigned ScratchSpacePointerInReg = 0;
 135
 136 #if defined(__GNUC__) && (defined(__clang__) || LLVM_GNUC_PREREQ(8, 0, 0))
 137   // FIXME: GCC7 bug workaround. Drop #if after GCC7 no longer supported.
 138 private:
 139 #endif
 140   CodeTemplate(const CodeTemplate &);            // default
 141   CodeTemplate &operator=(const CodeTemplate &); // default
 142 };
 143
 144 } // namespace exegesis
 145 } // namespace llvm
 146
 147 #endif // LLVM_TOOLS_LLVM_EXEGESIS_CODETEMPLATE_H