llvm/Target/TargetInstrInfo.h

//===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file describes the target machine instructions to the code generator.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TARGET_TARGETINSTRINFO_H
#define LLVM_TARGET_TARGETINSTRINFO_H

#include "Support/DataTypes.h"
#include <vector>
#include <cassert>

namespace llvm {

class MachineInstr;
class TargetMachine;
class Value;
class Type;
class Instruction;
class Constant;
class Function;
class MachineCodeForInstruction;

//---------------------------------------------------------------------------
// Data types used to define information about a single machine instruction
//---------------------------------------------------------------------------

typedef int MachineOpCode;
typedef unsigned InstrSchedClass;

const MachineOpCode INVALID_MACHINE_OPCODE = -1;


//---------------------------------------------------------------------------
// struct TargetInstrDescriptor:
//	Predefined information about each machine instruction.
//	Designed to initialized statically.
//

const unsigned M_NOP_FLAG		= 1 << 0;
const unsigned M_BRANCH_FLAG		= 1 << 1;
const unsigned M_CALL_FLAG		= 1 << 2;
const unsigned M_RET_FLAG		= 1 << 3;
const unsigned M_ARITH_FLAG		= 1 << 4;
const unsigned M_CC_FLAG		= 1 << 6;
const unsigned M_LOGICAL_FLAG		= 1 << 6;
const unsigned M_INT_FLAG		= 1 << 7;
const unsigned M_FLOAT_FLAG		= 1 << 8;
const unsigned M_CONDL_FLAG		= 1 << 9;
const unsigned M_LOAD_FLAG		= 1 << 10;
const unsigned M_PREFETCH_FLAG		= 1 << 11;
const unsigned M_STORE_FLAG		= 1 << 12;
const unsigned M_DUMMY_PHI_FLAG	= 1 << 13;
const unsigned M_PSEUDO_FLAG           = 1 << 14;       // Pseudo instruction
// 3-addr instructions which really work like 2-addr ones, eg. X86 add/sub
const unsigned M_2_ADDR_FLAG           = 1 << 15;

// M_TERMINATOR_FLAG - Is this instruction part of the terminator for a basic
// block?  Typically this is things like return and branch instructions.
// Various passes use this to insert code into the bottom of a basic block, but
// before control flow occurs.
const unsigned M_TERMINATOR_FLAG       = 1 << 16;

struct TargetInstrDescriptor {
  const char *    Name;          // Assembly language mnemonic for the opcode.
  int             numOperands;   // Number of args; -1 if variable #args
  int             resultPos;     // Position of the result; -1 if no result
  unsigned        maxImmedConst; // Largest +ve constant in IMMMED field or 0.
  bool	          immedIsSignExtended; // Is IMMED field sign-extended? If so,
                                 //   smallest -ve value is -(maxImmedConst+1).
  unsigned        numDelaySlots; // Number of delay slots after instruction
  unsigned        latency;       // Latency in machine cycles
  InstrSchedClass schedClass;    // enum  identifying instr sched class
  unsigned        Flags;         // flags identifying machine instr class
  unsigned        TSFlags;       // Target Specific Flag values
  const unsigned *ImplicitUses;  // Registers implicitly read by this instr
  const unsigned *ImplicitDefs;  // Registers implicitly defined by this instr
};


//---------------------------------------------------------------------------
///
/// TargetInstrInfo - Interface to description of machine instructions
///
class TargetInstrInfo {
  const TargetInstrDescriptor* desc;    // raw array to allow static init'n
  unsigned descSize;                    // number of entries in the desc array
  unsigned numRealOpCodes;              // number of non-dummy op codes

  TargetInstrInfo(const TargetInstrInfo &);  // DO NOT IMPLEMENT
  void operator=(const TargetInstrInfo &);   // DO NOT IMPLEMENT
public:
  TargetInstrInfo(const TargetInstrDescriptor *desc, unsigned descSize,
		  unsigned numRealOpCodes);
  virtual ~TargetInstrInfo();

  // Invariant: All instruction sets use opcode #0 as the PHI instruction
  enum { PHI = 0 };

  unsigned getNumRealOpCodes()  const { return numRealOpCodes; }
  unsigned getNumTotalOpCodes() const { return descSize; }

  /// get - Return the machine instruction descriptor that corresponds to the
  /// specified instruction opcode.
  ///
  const TargetInstrDescriptor& get(MachineOpCode opCode) const {
    assert(opCode >= 0 && opCode < (int)descSize);
    return desc[opCode];
  }

  const char *getName(MachineOpCode opCode) const {
    return get(opCode).Name;
  }

  int getNumOperands(MachineOpCode opCode) const {
    return get(opCode).numOperands;
  }

  int getResultPos(MachineOpCode opCode) const {
    return get(opCode).resultPos;
  }

  unsigned getNumDelaySlots(MachineOpCode opCode) const {
    return get(opCode).numDelaySlots;
  }

  InstrSchedClass getSchedClass(MachineOpCode opCode) const {
    return get(opCode).schedClass;
  }

  const unsigned *getImplicitUses(MachineOpCode opCode) const {
    return get(opCode).ImplicitUses;
  }

  const unsigned *getImplicitDefs(MachineOpCode opCode) const {
    return get(opCode).ImplicitDefs;
  }

  //
  // Query instruction class flags according to the machine-independent
  // flags listed above.
  //
  bool isNop(MachineOpCode opCode) const {
    return get(opCode).Flags & M_NOP_FLAG;
  }
  bool isBranch(MachineOpCode opCode) const {
    return get(opCode).Flags & M_BRANCH_FLAG;
  }
  bool isCall(MachineOpCode opCode) const {
    return get(opCode).Flags & M_CALL_FLAG;
  }
  bool isReturn(MachineOpCode opCode) const {
    return get(opCode).Flags & M_RET_FLAG;
  }
  bool isControlFlow(MachineOpCode opCode) const {
    return get(opCode).Flags & M_BRANCH_FLAG
        || get(opCode).Flags & M_CALL_FLAG
        || get(opCode).Flags & M_RET_FLAG;
  }
  bool isArith(MachineOpCode opCode) const {
    return get(opCode).Flags & M_ARITH_FLAG;
  }
  bool isCCInstr(MachineOpCode opCode) const {
    return get(opCode).Flags & M_CC_FLAG;
  }
  bool isLogical(MachineOpCode opCode) const {
    return get(opCode).Flags & M_LOGICAL_FLAG;
  }
  bool isIntInstr(MachineOpCode opCode) const {
    return get(opCode).Flags & M_INT_FLAG;
  }
  bool isFloatInstr(MachineOpCode opCode) const {
    return get(opCode).Flags & M_FLOAT_FLAG;
  }
  bool isConditional(MachineOpCode opCode) const {
    return get(opCode).Flags & M_CONDL_FLAG;
  }
  bool isLoad(MachineOpCode opCode) const {
    return get(opCode).Flags & M_LOAD_FLAG;
  }
  bool isPrefetch(MachineOpCode opCode) const {
    return get(opCode).Flags & M_PREFETCH_FLAG;
  }
  bool isLoadOrPrefetch(MachineOpCode opCode) const {
    return get(opCode).Flags & M_LOAD_FLAG
        || get(opCode).Flags & M_PREFETCH_FLAG;
  }
  bool isStore(MachineOpCode opCode) const {
    return get(opCode).Flags & M_STORE_FLAG;
  }
  bool isMemoryAccess(MachineOpCode opCode) const {
    return get(opCode).Flags & M_LOAD_FLAG
        || get(opCode).Flags & M_PREFETCH_FLAG
        || get(opCode).Flags & M_STORE_FLAG;
  }
  bool isDummyPhiInstr(MachineOpCode opCode) const {
    return get(opCode).Flags & M_DUMMY_PHI_FLAG;
  }
  bool isPseudoInstr(MachineOpCode opCode) const {
    return get(opCode).Flags & M_PSEUDO_FLAG;
  }
  bool isTwoAddrInstr(MachineOpCode opCode) const {
    return get(opCode).Flags & M_2_ADDR_FLAG;
  }
  bool isTerminatorInstr(unsigned Opcode) const {
    return get(Opcode).Flags & M_TERMINATOR_FLAG;
  }

  //
  // Return true if the instruction is a register to register move and
  // leave the source and dest operands in the passed parameters.
  //
  virtual bool isMoveInstr(const MachineInstr& MI,
                           unsigned& sourceReg,
                           unsigned& destReg) const {
    return false;
  }

  // Check if an instruction can be issued before its operands are ready,
  // or if a subsequent instruction that uses its result can be issued
  // before the results are ready.
  // Default to true since most instructions on many architectures allow this.
  //
  virtual bool hasOperandInterlock(MachineOpCode opCode) const {
    return true;
  }

  virtual bool hasResultInterlock(MachineOpCode opCode) const {
    return true;
  }

  //
  // Latencies for individual instructions and instruction pairs
  //
  virtual int minLatency(MachineOpCode opCode) const {
    return get(opCode).latency;
  }

  virtual int maxLatency(MachineOpCode opCode) const {
    return get(opCode).latency;
  }

  //
  // Which operand holds an immediate constant?  Returns -1 if none
  //
  virtual int getImmedConstantPos(MachineOpCode opCode) const {
    return -1; // immediate position is machine specific, so say -1 == "none"
  }

  // Check if the specified constant fits in the immediate field
  // of this machine instruction
  //
  virtual bool constantFitsInImmedField(MachineOpCode opCode,
					int64_t intValue) const;

  // Return the largest +ve constant that can be held in the IMMMED field
  // of this machine instruction.
  // isSignExtended is set to true if the value is sign-extended before use
  // (this is true for all immediate fields in SPARC instructions).
  // Return 0 if the instruction has no IMMED field.
  //
  virtual uint64_t maxImmedConstant(MachineOpCode opCode,
				    bool &isSignExtended) const {
    isSignExtended = get(opCode).immedIsSignExtended;
    return get(opCode).maxImmedConst;
  }

  //-------------------------------------------------------------------------
  // Queries about representation of LLVM quantities (e.g., constants)
  //-------------------------------------------------------------------------

  /// ConstantTypeMustBeLoaded - Test if this type of constant must be loaded
  /// from memory into a register, i.e., cannot be set bitwise in register and
  /// cannot use immediate fields of instructions.  Note that this only makes
  /// sense for primitive types.
  ///
  virtual bool ConstantTypeMustBeLoaded(const Constant* CV) const;

  // Test if this constant may not fit in the immediate field of the
  // machine instructions (probably) generated for this instruction.
  //
  virtual bool ConstantMayNotFitInImmedField(const Constant* CV,
                                             const Instruction* I) const {
    return true;                        // safe but very conservative
  }


  /// createNOPinstr - returns the target's implementation of NOP, which is
  /// usually a pseudo-instruction, implemented by a degenerate version of
  /// another instruction, e.g. X86: xchg ax, ax; SparcV9: sethi g0, 0
  ///
  virtual MachineInstr* createNOPinstr() const = 0;

  /// isNOPinstr - not having a special NOP opcode, we need to know if a given
  /// instruction is interpreted as an `official' NOP instr, i.e., there may be
  /// more than one way to `do nothing' but only one canonical way to slack off.
  ///
  virtual bool isNOPinstr(const MachineInstr &MI) const = 0;

  //-------------------------------------------------------------------------
  // Code generation support for creating individual machine instructions
  //
  // WARNING: These methods are Sparc specific
  //
  //-------------------------------------------------------------------------

  // Get certain common op codes for the current target.  this and all the
  // Create* methods below should be moved to a machine code generation class
  //
  virtual MachineOpCode getNOPOpCode() const { abort(); }

  // Get the value of an integral constant in the form that must
  // be put into the machine register.  The specified constant is interpreted
  // as (i.e., converted if necessary to) the specified destination type.  The
  // result is always returned as an uint64_t, since the representation of
  // int64_t and uint64_t are identical.  The argument can be any known const.
  //
  // isValidConstant is set to true if a valid constant was found.
  //
  virtual uint64_t ConvertConstantToIntType(const TargetMachine &target,
                                            const Value *V,
                                            const Type *destType,
                                            bool  &isValidConstant) const {
    abort();
  }

  // Create an instruction sequence to put the constant `val' into
  // the virtual register `dest'.  `val' may be a Constant or a
  // GlobalValue, viz., the constant address of a global variable or function.
  // The generated instructions are returned in `mvec'.
  // Any temp. registers (TmpInstruction) created are recorded in mcfi.
  // Symbolic constants or constants that must be accessed from memory
  // are added to the constant pool via MachineFunction::get(F).
  //
  virtual void  CreateCodeToLoadConst(const TargetMachine& target,
                                      Function* F,
                                      Value* val,
                                      Instruction* dest,
                                      std::vector<MachineInstr*>& mvec,
                                      MachineCodeForInstruction& mcfi) const {
    abort();
  }

  // Create an instruction sequence to copy an integer value `val'
  // to a floating point value `dest' by copying to memory and back.
  // val must be an integral type.  dest must be a Float or Double.
  // The generated instructions are returned in `mvec'.
  // Any temp. registers (TmpInstruction) created are recorded in mcfi.
  // Any stack space required is allocated via mcff.
  //
  virtual void CreateCodeToCopyIntToFloat(const TargetMachine& target,
					  Function* F,
					  Value* val,
					  Instruction* dest,
					  std::vector<MachineInstr*>& mvec,
					  MachineCodeForInstruction& MI) const {
    abort();
  }

  // Similarly, create an instruction sequence to copy an FP value
  // `val' to an integer value `dest' by copying to memory and back.
  // The generated instructions are returned in `mvec'.
  // Any temp. registers (TmpInstruction) created are recorded in mcfi.
  // Any stack space required is allocated via mcff.
  //
  virtual void CreateCodeToCopyFloatToInt(const TargetMachine& target,
					  Function* F,
					  Value* val,
					  Instruction* dest,
					  std::vector<MachineInstr*>& mvec,
					  MachineCodeForInstruction& MI) const {
    abort();
  }

  // Create instruction(s) to copy src to dest, for arbitrary types
  // The generated instructions are returned in `mvec'.
  // Any temp. registers (TmpInstruction) created are recorded in mcfi.
  // Any stack space required is allocated via mcff.
  //
  virtual void CreateCopyInstructionsByType(const TargetMachine& target,
					    Function* F,
					    Value* src,
					    Instruction* dest,
					    std::vector<MachineInstr*>& mvec,
                                          MachineCodeForInstruction& MI) const {
    abort();
  }

  // Create instruction sequence to produce a sign-extended register value
  // from an arbitrary sized value (sized in bits, not bytes).
  // The generated instructions are appended to `mvec'.
  // Any temp. registers (TmpInstruction) created are recorded in mcfi.
  // Any stack space required is allocated via mcff.
  //
  virtual void CreateSignExtensionInstructions(const TargetMachine& target,
                                       Function* F,
                                       Value* srcVal,
                                       Value* destVal,
                                       unsigned numLowBits,
                                       std::vector<MachineInstr*>& mvec,
				       MachineCodeForInstruction& MI) const {
    abort();
  }

  // Create instruction sequence to produce a zero-extended register value
  // from an arbitrary sized value (sized in bits, not bytes).
  // The generated instructions are appended to `mvec'.
  // Any temp. registers (TmpInstruction) created are recorded in mcfi.
  // Any stack space required is allocated via mcff.
  //
  virtual void CreateZeroExtensionInstructions(const TargetMachine& target,
                                       Function* F,
                                       Value* srcVal,
                                       Value* destVal,
                                       unsigned srcSizeInBits,
                                       std::vector<MachineInstr*>& mvec,
                                       MachineCodeForInstruction& mcfi) const {
    abort();
  }
};

} // End llvm namespace

#endif