i386.md

gcc库的原代码,对编程有很大帮助.

(define_expand "movqi"
  [(set (match_operand:QI 0 "general_operand" "")
	(match_operand:QI 1 "general_operand" ""))]
  ""
  "
{
  /* Don't generate memory->memory moves, go through a register */
  if (TARGET_MOVE
      && (reload_in_progress | reload_completed) == 0
      && GET_CODE (operands[0]) == MEM
      && GET_CODE (operands[1]) == MEM)
    {
      operands[1] = force_reg (QImode, operands[1]);
    }
}")

(define_insn ""
  [(set (match_operand:QI 0 "general_operand" "=q,*r,qm")
	(match_operand:QI 1 "general_operand" "*g,q,qn"))]
  "(!TARGET_MOVE || GET_CODE (operands[0]) != MEM) || (GET_CODE (operands[1]) != MEM)"
  "*
{
  rtx link;
  if (operands[1] == const0_rtx && REG_P (operands[0]))
    return AS2 (xor%B0,%0,%0);

  if (operands[1] == const1_rtx
      && (link = find_reg_note (insn, REG_WAS_0, 0))
      /* Make sure the insn that stored the 0 is still present.  */
      && ! INSN_DELETED_P (XEXP (link, 0))
      && GET_CODE (XEXP (link, 0)) != NOTE
      /* Make sure cross jumping didn't happen here.  */
      && no_labels_between_p (XEXP (link, 0), insn)
      /* Make sure the reg hasn't been clobbered.  */
      && ! reg_set_between_p (operands[0], XEXP (link, 0), insn))
    /* Fastest way to change a 0 to a 1.  */
    return AS1 (inc%B0,%0);

  /* If mov%B0 isn't allowed for one of these regs, use mov%L0.  */
  if (NON_QI_REG_P (operands[0]) || NON_QI_REG_P (operands[1]))
    return (AS2 (mov%L0,%k1,%k0));

  return (AS2 (mov%B0,%1,%0));
}")

;; If it becomes necessary to support movstrictqi into %esi or %edi,
;; use the insn sequence:
;;
;;	shrdl $8,srcreg,dstreg
;;	rorl $24,dstreg
;;
;; If operands[1] is a constant, then an andl/orl sequence would be
;; faster.

(define_expand "movstrictqi"
  [(set (strict_low_part (match_operand:QI 0 "general_operand" ""))
	(match_operand:QI 1 "general_operand" ""))]
  ""
  "
{
  /* Don't generate memory->memory moves, go through a register */
  if (TARGET_MOVE
      && (reload_in_progress | reload_completed) == 0
      && GET_CODE (operands[0]) == MEM
      && GET_CODE (operands[1]) == MEM)
    {
      operands[1] = force_reg (QImode, operands[1]);
    }
}")

(define_insn ""
  [(set (strict_low_part (match_operand:QI 0 "general_operand" "+qm,q"))
	(match_operand:QI 1 "general_operand" "*qn,m"))]
  "(!TARGET_MOVE || GET_CODE (operands[0]) != MEM) || (GET_CODE (operands[1]) != MEM)"
  "*
{
  rtx link;
  if (operands[1] == const0_rtx && REG_P (operands[0]))
    return AS2 (xor%B0,%0,%0);

  if (operands[1] == const1_rtx
      && (link = find_reg_note (insn, REG_WAS_0, 0))
      /* Make sure the insn that stored the 0 is still present.  */
      && ! INSN_DELETED_P (XEXP (link, 0))
      && GET_CODE (XEXP (link, 0)) != NOTE
      /* Make sure cross jumping didn't happen here.  */
      && no_labels_between_p (XEXP (link, 0), insn)
      /* Make sure the reg hasn't been clobbered.  */
      && ! reg_set_between_p (operands[0], XEXP (link, 0), insn))
    /* Fastest way to change a 0 to a 1.  */
    return AS1 (inc%B0,%0);

  /* If mov%B0 isn't allowed for one of these regs, use mov%L0.  */
  if (NON_QI_REG_P (operands[0]) || NON_QI_REG_P (operands[1]))
    {
      abort ();
      return (AS2 (mov%L0,%k1,%k0));
    }

  return AS2 (mov%B0,%1,%0);
}")

(define_expand "movsf"
  [(set (match_operand:SF 0 "general_operand" "")
	(match_operand:SF 1 "general_operand" ""))]
  ""
  "
{
  /* Special case memory->memory moves and pushes */
  if (TARGET_MOVE
      && (reload_in_progress | reload_completed) == 0
      && GET_CODE (operands[0]) == MEM
      && (GET_CODE (operands[1]) == MEM || push_operand (operands[0], SFmode)))
    {
      rtx (*genfunc) PROTO((rtx, rtx)) = (push_operand (operands[0], SFmode))
						? gen_movsf_push
						: gen_movsf_mem;

      emit_insn ((*genfunc) (operands[0], operands[1]));
      DONE;
    }

  /* If we are loading a floating point constant that isn't 0 or 1 into a register,
     indicate we need the pic register loaded.  This could be optimized into stores
     of constants if the target eventually moves to memory, but better safe than
     sorry.  */
  if (flag_pic
      && GET_CODE (operands[0]) != MEM
      && GET_CODE (operands[1]) == CONST_DOUBLE
      && !standard_80387_constant_p (operands[1]))
    {
      current_function_uses_pic_offset_table = 1;
    }
}")

(define_insn "movsf_push_nomove"
  [(set (match_operand:SF 0 "push_operand" "=<,<")
	(match_operand:SF 1 "general_operand" "gF,f"))]
  "!TARGET_MOVE"
  "*
{
  if (STACK_REG_P (operands[1]))
    {
      rtx xops[3];

      if (! STACK_TOP_P (operands[1]))
        abort ();

      xops[0] = AT_SP (SFmode);
      xops[1] = GEN_INT (4);
      xops[2] = stack_pointer_rtx;

      output_asm_insn (AS2 (sub%L2,%1,%2), xops);

      if (find_regno_note (insn, REG_DEAD, FIRST_STACK_REG))
        output_asm_insn (AS1 (fstp%S0,%0), xops);
      else
        output_asm_insn (AS1 (fst%S0,%0), xops);
      RET;
    }
  return AS1 (push%L1,%1);
}")

(define_insn "movsf_push"
  [(set (match_operand:SF 0 "push_operand" "=<,<,<,<")
	(match_operand:SF 1 "general_operand" "rF,f,m,m"))
   (clobber (match_scratch:SI 2 "=X,X,r,X"))]
  ""
  "*
{
  if (STACK_REG_P (operands[1]))
    {
      rtx xops[3];

      if (! STACK_TOP_P (operands[1]))
        abort ();

      xops[0] = AT_SP (SFmode);
      xops[1] = GEN_INT (4);
      xops[2] = stack_pointer_rtx;

      output_asm_insn (AS2 (sub%L2,%1,%2), xops);

      if (find_regno_note (insn, REG_DEAD, FIRST_STACK_REG))
        output_asm_insn (AS1 (fstp%S0,%0), xops);
      else
        output_asm_insn (AS1 (fst%S0,%0), xops);
      RET;
    }

  else if (GET_CODE (operands[1]) != MEM || GET_CODE (operands[2]) != REG)
    return AS1 (push%L1,%1);

  else
    {
      output_asm_insn (AS2 (mov%L2,%1,%2), operands);
      return AS1 (push%L2,%2);
    }
}")

;; Special memory<->memory pattern that combine will recreate from the
;; moves to pseudos.
(define_insn "movsf_mem"
  [(set (match_operand:SF 0 "memory_operand" "=m")
	(match_operand:SF 1 "memory_operand" "m"))
   (clobber (match_scratch:SI 2 "=&r"))]
  ""
  "*
{
  output_asm_insn (AS2 (mov%L2,%1,%2), operands);
  return AS2 (mov%L0,%2,%0);
}")

;; For the purposes of regclass, prefer FLOAT_REGS.
(define_insn "movsf_normal"
  [(set (match_operand:SF 0 "general_operand" "=*rfm,*rf,f,!*rm")
	(match_operand:SF 1 "general_operand" "*rf,*rfm,fG,fF"))]
  "(!TARGET_MOVE || GET_CODE (operands[0]) != MEM) || (GET_CODE (operands[1]) != MEM)"
  "*
{
  int stack_top_dies = find_regno_note (insn, REG_DEAD, FIRST_STACK_REG) != 0;

  /* First handle a `pop' insn or a `fld %st(0)' */

  if (STACK_TOP_P (operands[0]) && STACK_TOP_P (operands[1]))
    {
      if (stack_top_dies)
	return AS1 (fstp,%y0);
      else
        return AS1 (fld,%y0);
    }

  /* Handle a transfer between the 387 and a 386 register */

  if (STACK_TOP_P (operands[0]) && NON_STACK_REG_P (operands[1]))
    {
      output_op_from_reg (operands[1], AS1 (fld%z0,%y1));
      RET;
    }

  if (STACK_TOP_P (operands[1]) && NON_STACK_REG_P (operands[0]))
    {
      output_to_reg (operands[0], stack_top_dies);
      RET;
    }

  /* Handle other kinds of writes from the 387 */

  if (STACK_TOP_P (operands[1]))
    {
      if (stack_top_dies)
	return AS1 (fstp%z0,%y0);
      else
        return AS1 (fst%z0,%y0);
    }

  /* Handle other kinds of reads to the 387 */

  if (STACK_TOP_P (operands[0]) && GET_CODE (operands[1]) == CONST_DOUBLE)
    return output_move_const_single (operands);

  if (STACK_TOP_P (operands[0]))
    return AS1 (fld%z1,%y1);

  /* Handle all SFmode moves not involving the 387 */

  return singlemove_string (operands);
}")

(define_insn "swapsf"
  [(set (match_operand:SF 0 "register_operand" "f")
	(match_operand:SF 1 "register_operand" "f"))
   (set (match_dup 1)
	(match_dup 0))]
  ""
  "*
{
  if (STACK_TOP_P (operands[0]))
    return AS1 (fxch,%1);
  else
    return AS1 (fxch,%0);
}")

(define_expand "movdf"
  [(set (match_operand:DF 0 "general_operand" "")
	(match_operand:DF 1 "general_operand" ""))]
  ""
  "
{
  /* Special case memory->memory moves and pushes */
  if (TARGET_MOVE
      && (reload_in_progress | reload_completed) == 0
      && GET_CODE (operands[0]) == MEM
      && (GET_CODE (operands[1]) == MEM || push_operand (operands[0], DFmode)))
    {
      rtx (*genfunc) PROTO((rtx, rtx)) = (push_operand (operands[0], DFmode))
						? gen_movdf_push
						: gen_movdf_mem;

      emit_insn ((*genfunc) (operands[0], operands[1]));
      DONE;
    }

  /* If we are loading a floating point constant that isn't 0 or 1 into a register,
     indicate we need the pic register loaded.  This could be optimized into stores
     of constants if the target eventually moves to memory, but better safe than
     sorry.  */
  if (flag_pic
      && GET_CODE (operands[0]) != MEM
      && GET_CODE (operands[1]) == CONST_DOUBLE
      && !standard_80387_constant_p (operands[1]))
    {
      current_function_uses_pic_offset_table = 1;
    }
}")

(define_insn "movdf_push_nomove"
  [(set (match_operand:DF 0 "push_operand" "=<,<")
	(match_operand:DF 1 "general_operand" "gF,f"))]
  "!TARGET_MOVE"
  "*
{
  if (STACK_REG_P (operands[1]))
    {
      rtx xops[3];

      xops[0] = AT_SP (SFmode);
      xops[1] = GEN_INT (8);
      xops[2] = stack_pointer_rtx;

      output_asm_insn (AS2 (sub%L2,%1,%2), xops);

      if (find_regno_note (insn, REG_DEAD, FIRST_STACK_REG))
        output_asm_insn (AS1 (fstp%Q0,%0), xops);
      else
        output_asm_insn (AS1 (fst%Q0,%0), xops);

      RET;
    }
  else
    return output_move_double (operands);
}")

(define_insn "movdf_push"
  [(set (match_operand:DF 0 "push_operand" "=<,<,<,<,<")
	(match_operand:DF 1 "general_operand" "rF,f,o,o,o"))
   (clobber (match_scratch:SI 2 "=X,X,&r,&r,X"))
   (clobber (match_scratch:SI 3 "=X,X,&r,X,X"))]
  ""
  "*
{
  if (STACK_REG_P (operands[1]))
    {
      rtx xops[3];

      xops[0] = AT_SP (SFmode);
      xops[1] = GEN_INT (8);
      xops[2] = stack_pointer_rtx;

      output_asm_insn (AS2 (sub%L2,%1,%2), xops);

      if (find_regno_note (insn, REG_DEAD, FIRST_STACK_REG))
        output_asm_insn (AS1 (fstp%Q0,%0), xops);
      else
        output_asm_insn (AS1 (fst%Q0,%0), xops);

      RET;
    }

  else if (GET_CODE (operands[1]) != MEM)
    return output_move_double (operands);

  else
    return output_move_pushmem (operands, insn, GET_MODE_SIZE (DFmode), 2, 4);
}")

(define_insn "movdf_mem"
  [(set (match_operand:DF 0 "memory_operand" "=o,o")
	(match_operand:DF 1 "memory_operand" "o,o"))
   (clobber (match_scratch:SI 2 "=&r,&r"))
   (clobber (match_scratch:SI 3 "=&r,X"))]
  ""
  "* return output_move_memory (operands, insn, GET_MODE_SIZE (DFmode), 2, 4);")

;; For the purposes of regclass, prefer FLOAT_REGS.
(define_insn "movdf_normal"
  [(set (match_operand:DF 0 "general_operand" "=f,fm,!*rf,!*rm")
	(match_operand:DF 1 "general_operand" "fmG,f,*rfm,*rfF"))]
  "(!TARGET_MOVE || GET_CODE (operands[0]) != MEM) || (GET_CODE (operands[1]) != MEM)"
  "*
{
  int stack_top_dies = find_regno_note (insn, REG_DEAD, FIRST_STACK_REG) != 0;

  /* First handle a `pop' insn or a `fld %st(0)' */

  if (STACK_TOP_P (operands[0]) && STACK_TOP_P (operands[1]))
    {
      if (stack_top_dies)
	return AS1 (fstp,%y0);
      else
        return AS1 (fld,%y0);
    }

  /* Handle a transfer between the 387 and a 386 register */

  if (STACK_TOP_P (operands[0]) && NON_STACK_REG_P (operands[1]))
    {
      output_op_from_reg (operands[1], AS1 (fld%z0,%y1));
      RET;
    }

  if (STACK_TOP_P (operands[1]) && NON_STACK_REG_P (operands[0]))
    {
      output_to_reg (operands[0], stack_top_dies);
      RET;
    }

  /* Handle other kinds of writes from the 387 */

  if (STACK_TOP_P (operands[1]))
    {
      if (stack_top_dies)
	return AS1 (fstp%z0,%y0);
      else
        return AS1 (fst%z0,%y0);
    }

  /* Handle other kinds of reads to the 387 */

  if (STACK_TOP_P (operands[0]) && GET_CODE (operands[1]) == CONST_DOUBLE)
    return output_move_const_single (operands);

  if (STACK_TOP_P (operands[0]))
    return AS1 (fld%z1,%y1);

  /* Handle all DFmode moves not involving the 387 */

  return output_move_double (operands);
}")

(define_insn "swapdf"
  [(set (match_operand:DF 0 "register_operand" "f")
	(match_operand:DF 1 "register_operand" "f"))
   (set (match_dup 1)
	(match_dup 0))]
  ""
  "*
{
  if (STACK_TOP_P (operands[0]))
    return AS1 (fxch,%1);
  else
    return AS1 (fxch,%0);
}")

(define_expand "movxf"
  [(set (match_operand:XF 0 "general_operand" "")
	(match_operand:XF 1 "general_operand" ""))]
  ""
  "
{
  /* Special case memory->memory moves and pushes */
  if (TARGET_MOVE
      && (reload_in_progress | reload_completed) == 0
      && GET_CODE (operands[0]) == MEM
      && (GET_CODE (operands[1]) == MEM || push_operand (operands[0], XFmode)))
    {
      rtx (*genfunc) PROTO((rtx, rtx)) = (push_operand (operands[0], XFmode))
						? gen_movxf_push
						: gen_movxf_mem;

      emit_insn ((*genfunc) (operands[0], operands[1]));
      DONE;
    }

  /* If we are loading a floating point constant that isn't 0 or 1 into a register,
     indicate we need the pic register loaded.  This could be optimized into stores
     of constants if the target eventually moves to memory, but better safe than
     sorry.  */
  if (flag_pic
      && GET_CODE (operands[0]) != MEM