utils/TableGen/X86RecognizableInstr.h

   1 //===- X86RecognizableInstr.h - Disassembler instruction spec ----*- 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 // This file is part of the X86 Disassembler Emitter.
  11 // It contains the interface of a single recognizable instruction.
  12 // Documentation for the disassembler emitter in general can be found in
  13 //  X86DisasemblerEmitter.h.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #ifndef X86RECOGNIZABLEINSTR_H
  18 #define X86RECOGNIZABLEINSTR_H
  19
  20 #include "X86DisassemblerTables.h"
  21
  22 #include "CodeGenTarget.h"
  23 #include "Record.h"
  24
  25 #include "llvm/Support/DataTypes.h"
  26 #include "llvm/ADT/SmallVector.h"
  27
  28 namespace llvm {
  29
  30 namespace X86Disassembler {
  31
  32 /// RecognizableInstr - Encapsulates all information required to decode a single
  33 ///   instruction, as extracted from the LLVM instruction tables.  Has methods
  34 ///   to interpret the information available in the LLVM tables, and to emit the
  35 ///   instruction into DisassemblerTables.
  36 class RecognizableInstr {
  37 private:
  38   /// The opcode of the instruction, as used in an MCInst
  39   InstrUID UID;
  40   /// The record from the .td files corresponding to this instruction
  41   const Record* Rec;
  42   /// The prefix field from the record
  43   uint8_t Prefix;
  44   /// The opcode field from the record; this is the opcode used in the Intel
  45   /// encoding and therefore distinct from the UID
  46   uint8_t Opcode;
  47   /// The form field from the record
  48   uint8_t Form;
  49   /// The segment override field from the record
  50   uint8_t SegOvr;
  51   /// The hasOpSizePrefix field from the record
  52   bool HasOpSizePrefix;
  53   /// The hasREX_WPrefix field from the record
  54   bool HasREX_WPrefix;
  55   /// The hasVEX_4VPrefix field from the record
  56   bool HasVEX_4VPrefix;
  57   /// The hasLockPrefix field from the record
  58   bool HasLockPrefix;
  59   /// The isCodeGenOnly filed from the record
  60   bool IsCodeGenOnly;
  61
  62   /// The instruction name as listed in the tables
  63   std::string Name;
  64   /// The AT&T AsmString for the instruction
  65   std::string AsmString;
  66
  67   /// Indicates whether the instruction is SSE
  68   bool IsSSE;
  69   /// Indicates whether the instruction has FR operands - MOVs with FR operands
  70   /// are typically ignored
  71   bool HasFROperands;
  72   /// Indicates whether the instruction should be emitted into the decode
  73   /// tables; regardless, it will be emitted into the instruction info table
  74   bool ShouldBeEmitted;
  75
  76   /// The operands of the instruction, as listed in the CodeGenInstruction.
  77   /// They are not one-to-one with operands listed in the MCInst; for example,
  78   /// memory operands expand to 5 operands in the MCInst
  79   const std::vector<CGIOperandList::OperandInfo>* Operands;
  80
  81   /// The description of the instruction that is emitted into the instruction
  82   /// info table
  83   InstructionSpecifier* Spec;
  84
  85   /// insnContext - Returns the primary context in which the instruction is
  86   ///   valid.
  87   ///
  88   /// @return - The context in which the instruction is valid.
  89   InstructionContext insnContext() const;
  90
  91   enum filter_ret {
  92     FILTER_STRONG,    // instruction has no place in the instruction tables
  93     FILTER_WEAK,      // instruction may conflict, and should be eliminated if
  94                       // it does
  95     FILTER_NORMAL     // instruction should have high priority and generate an
  96                       // error if it conflcits with any other FILTER_NORMAL
  97                       // instruction
  98   };
  99
 100   /// filter - Determines whether the instruction should be decodable.  Some
 101   ///   instructions are pure intrinsics and use unencodable operands; many
 102   ///   synthetic instructions are duplicates of other instructions; other
 103   ///   instructions only differ in the logical way in which they are used, and
 104   ///   have the same decoding.  Because these would cause decode conflicts,
 105   ///   they must be filtered out.
 106   ///
 107   /// @return - The degree of filtering to be applied (see filter_ret).
 108   filter_ret filter() const;
 109
 110   /// typeFromString - Translates an operand type from the string provided in
 111   ///   the LLVM tables to an OperandType for use in the operand specifier.
 112   ///
 113   /// @param s              - The string, as extracted by calling Rec->getName()
 114   ///                         on a CodeGenInstruction::OperandInfo.
 115   /// @param isSSE          - Indicates whether the instruction is an SSE
 116   ///                         instruction.  For SSE instructions, immediates are
 117   ///                         fixed-size rather than being affected by the
 118   ///                         mandatory OpSize prefix.
 119   /// @param hasREX_WPrefix - Indicates whether the instruction has a REX.W
 120   ///                         prefix.  If it does, 32-bit register operands stay
 121   ///                         32-bit regardless of the operand size.
 122   /// @param hasOpSizePrefix- Indicates whether the instruction has an OpSize
 123   ///                         prefix.  If it does not, then 16-bit register
 124   ///                         operands stay 16-bit.
 125   /// @return               - The operand's type.
 126   static OperandType typeFromString(const std::string& s,
 127                                     bool isSSE,
 128                                     bool hasREX_WPrefix,
 129                                     bool hasOpSizePrefix);
 130
 131   /// immediateEncodingFromString - Translates an immediate encoding from the
 132   ///   string provided in the LLVM tables to an OperandEncoding for use in
 133   ///   the operand specifier.
 134   ///
 135   /// @param s                - See typeFromString().
 136   /// @param hasOpSizePrefix  - Indicates whether the instruction has an OpSize
 137   ///                           prefix.  If it does not, then 16-bit immediate
 138   ///                           operands stay 16-bit.
 139   /// @return                 - The operand's encoding.
 140   static OperandEncoding immediateEncodingFromString(const std::string &s,
 141                                                      bool hasOpSizePrefix);
 142
 143   /// rmRegisterEncodingFromString - Like immediateEncodingFromString, but
 144   ///   handles operands that are in the REG field of the ModR/M byte.
 145   static OperandEncoding rmRegisterEncodingFromString(const std::string &s,
 146                                                       bool hasOpSizePrefix);
 147
 148   /// rmRegisterEncodingFromString - Like immediateEncodingFromString, but
 149   ///   handles operands that are in the REG field of the ModR/M byte.
 150   static OperandEncoding roRegisterEncodingFromString(const std::string &s,
 151                                                       bool hasOpSizePrefix);
 152   static OperandEncoding memoryEncodingFromString(const std::string &s,
 153                                                   bool hasOpSizePrefix);
 154   static OperandEncoding relocationEncodingFromString(const std::string &s,
 155                                                       bool hasOpSizePrefix);
 156   static OperandEncoding opcodeModifierEncodingFromString(const std::string &s,
 157                                                           bool hasOpSizePrefix);
 158
 159   /// handleOperand - Converts a single operand from the LLVM table format to
 160   ///   the emitted table format, handling any duplicate operands it encounters
 161   ///   and then one non-duplicate.
 162   ///
 163   /// @param optional             - Determines whether to assert that the
 164   ///                               operand exists.
 165   /// @param operandIndex         - The index into the generated operand table.
 166   ///                               Incremented by this function one or more
 167   ///                               times to reflect possible duplicate
 168   ///                               operands).
 169   /// @param physicalOperandIndex - The index of the current operand into the
 170   ///                               set of non-duplicate ('physical') operands.
 171   ///                               Incremented by this function once.
 172   /// @param numPhysicalOperands  - The number of non-duplicate operands in the
 173   ///                               instructions.
 174   /// @param operandMapping       - The operand mapping, which has an entry for
 175   ///                               each operand that indicates whether it is a
 176   ///                               duplicate, and of what.
 177   void handleOperand(bool optional,
 178                      unsigned &operandIndex,
 179                      unsigned &physicalOperandIndex,
 180                      unsigned &numPhysicalOperands,
 181                      unsigned *operandMapping,
 182                      OperandEncoding (*encodingFromString)
 183                        (const std::string&,
 184                         bool hasOpSizePrefix));
 185
 186   /// shouldBeEmitted - Returns the shouldBeEmitted field.  Although filter()
 187   ///   filters out many instructions, at various points in decoding we
 188   ///   determine that the instruction should not actually be decodable.  In
 189   ///   particular, MMX MOV instructions aren't emitted, but they're only
 190   ///   identified during operand parsing.
 191   ///
 192   /// @return - true if at this point we believe the instruction should be
 193   ///   emitted; false if not.  This will return false if filter() returns false
 194   ///   once emitInstructionSpecifier() has been called.
 195   bool shouldBeEmitted() const {
 196     return ShouldBeEmitted;
 197   }
 198
 199   /// emitInstructionSpecifier - Loads the instruction specifier for the current
 200   ///   instruction into a DisassemblerTables.
 201   ///
 202   /// @arg tables - The DisassemblerTables to populate with the specifier for
 203   ///               the current instruction.
 204   void emitInstructionSpecifier(DisassemblerTables &tables);
 205
 206   /// emitDecodePath - Populates the proper fields in the decode tables
 207   ///   corresponding to the decode paths for this instruction.
 208   ///
 209   /// @arg tables - The DisassemblerTables to populate with the decode
 210   ///               decode information for the current instruction.
 211   void emitDecodePath(DisassemblerTables &tables) const;
 212
 213   /// Constructor - Initializes a RecognizableInstr with the appropriate fields
 214   ///   from a CodeGenInstruction.
 215   ///
 216   /// @arg tables - The DisassemblerTables that the specifier will be added to.
 217   /// @arg insn   - The CodeGenInstruction to extract information from.
 218   /// @arg uid    - The unique ID of the current instruction.
 219   RecognizableInstr(DisassemblerTables &tables,
 220                     const CodeGenInstruction &insn,
 221                     InstrUID uid);
 222 public:
 223   /// processInstr - Accepts a CodeGenInstruction and loads decode information
 224   ///   for it into a DisassemblerTables if appropriate.
 225   ///
 226   /// @arg tables - The DiassemblerTables to be populated with decode
 227   ///               information.
 228   /// @arg insn   - The CodeGenInstruction to be used as a source for this
 229   ///               information.
 230   /// @uid        - The unique ID of the instruction.
 231   static void processInstr(DisassemblerTables &tables,
 232                            const CodeGenInstruction &insn,
 233                            InstrUID uid);
 234 };
 235
 236 } // namespace X86Disassembler
 237
 238 } // namespace llvm
 239
 240 #endif