emit-rtl.c

早期freebsd实现

  /* Find out which word on the host machine this value is in and get
     it from the constant.  */
  val = (i / size_ratio == 0
	 ? (GET_CODE (op) == CONST_INT ? INTVAL (op) : CONST_DOUBLE_LOW (op))
	 : (GET_CODE (op) == CONST_INT
	    ? (INTVAL (op) < 0 ? ~0 : 0) : CONST_DOUBLE_HIGH (op)));

  /* If BITS_PER_WORD is smaller than an int, get the appropriate bits.  */
  if (BITS_PER_WORD < HOST_BITS_PER_WIDE_INT)
    val = ((val >> ((i % size_ratio) * BITS_PER_WORD))
	   & (((HOST_WIDE_INT) 1
	       << (BITS_PER_WORD % HOST_BITS_PER_WIDE_INT)) - 1));

  return GEN_INT (val);
}

/* Similar to `operand_subword', but never return 0.  If we can't extract
   the required subword, put OP into a register and try again.  If that fails,
   abort.  We always validate the address in this case.  It is not valid
   to call this function after reload; it is mostly meant for RTL
   generation. 

   MODE is the mode of OP, in case it is CONST_INT.  */

rtx
operand_subword_force (op, i, mode)
     rtx op;
     int i;
     enum machine_mode mode;
{
  rtx result = operand_subword (op, i, 1, mode);

  if (result)
    return result;

  if (mode != BLKmode && mode != VOIDmode)
    op = force_reg (mode, op);

  result = operand_subword (op, i, 1, mode);
  if (result == 0)
    abort ();

  return result;
}

/* Given a compare instruction, swap the operands.
   A test instruction is changed into a compare of 0 against the operand.  */

void
reverse_comparison (insn)
     rtx insn;
{
  rtx body = PATTERN (insn);
  rtx comp;

  if (GET_CODE (body) == SET)
    comp = SET_SRC (body);
  else
    comp = SET_SRC (XVECEXP (body, 0, 0));

  if (GET_CODE (comp) == COMPARE)
    {
      rtx op0 = XEXP (comp, 0);
      rtx op1 = XEXP (comp, 1);
      XEXP (comp, 0) = op1;
      XEXP (comp, 1) = op0;
    }
  else
    {
      rtx new = gen_rtx (COMPARE, VOIDmode,
			 CONST0_RTX (GET_MODE (comp)), comp);
      if (GET_CODE (body) == SET)
	SET_SRC (body) = new;
      else
	SET_SRC (XVECEXP (body, 0, 0)) = new;
    }
}

/* Return a memory reference like MEMREF, but with its mode changed
   to MODE and its address changed to ADDR.
   (VOIDmode means don't change the mode.
   NULL for ADDR means don't change the address.)  */

rtx
change_address (memref, mode, addr)
     rtx memref;
     enum machine_mode mode;
     rtx addr;
{
  rtx new;

  if (GET_CODE (memref) != MEM)
    abort ();
  if (mode == VOIDmode)
    mode = GET_MODE (memref);
  if (addr == 0)
    addr = XEXP (memref, 0);

  /* If reload is in progress or has completed, ADDR must be valid.
     Otherwise, we can call memory_address to make it valid.  */
  if (reload_completed || reload_in_progress)
    {
      if (! memory_address_p (mode, addr))
	abort ();
    }
  else
    addr = memory_address (mode, addr);
	
  new = gen_rtx (MEM, mode, addr);
  MEM_VOLATILE_P (new) = MEM_VOLATILE_P (memref);
  RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (memref);
  MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (memref);
  return new;
}

/* Return a newly created CODE_LABEL rtx with a unique label number.  */

rtx
gen_label_rtx ()
{
  register rtx label = gen_rtx (CODE_LABEL, VOIDmode, 0, 0, 0,
				label_num++, NULL_PTR);
  LABEL_NUSES (label) = 0;
  return label;
}

/* For procedure integration.  */

/* Return a newly created INLINE_HEADER rtx.  Should allocate this
   from a permanent obstack when the opportunity arises.  */

rtx
gen_inline_header_rtx (first_insn, first_parm_insn, first_labelno,
		       last_labelno, max_parm_regnum, max_regnum, args_size,
		       pops_args, stack_slots, function_flags,
		       outgoing_args_size, original_arg_vector,
		       original_decl_initial)
     rtx first_insn, first_parm_insn;
     int first_labelno, last_labelno, max_parm_regnum, max_regnum, args_size;
     int pops_args;
     rtx stack_slots;
     int function_flags;
     int outgoing_args_size;
     rtvec original_arg_vector;
     rtx original_decl_initial;
{
  rtx header = gen_rtx (INLINE_HEADER, VOIDmode,
			cur_insn_uid++, NULL_RTX,
			first_insn, first_parm_insn,
			first_labelno, last_labelno,
			max_parm_regnum, max_regnum, args_size, pops_args,
			stack_slots, function_flags, outgoing_args_size,
			original_arg_vector, original_decl_initial);
  return header;
}

/* Install new pointers to the first and last insns in the chain.
   Used for an inline-procedure after copying the insn chain.  */

void
set_new_first_and_last_insn (first, last)
     rtx first, last;
{
  first_insn = first;
  last_insn = last;
}

/* Set the range of label numbers found in the current function.
   This is used when belatedly compiling an inline function.  */

void
set_new_first_and_last_label_num (first, last)
     int first, last;
{
  base_label_num = label_num;
  first_label_num = first;
  last_label_num = last;
}

/* Save all variables describing the current status into the structure *P.
   This is used before starting a nested function.  */

void
save_emit_status (p)
     struct function *p;
{
  p->reg_rtx_no = reg_rtx_no;
  p->first_label_num = first_label_num;
  p->first_insn = first_insn;
  p->last_insn = last_insn;
  p->sequence_stack = sequence_stack;
  p->cur_insn_uid = cur_insn_uid;
  p->last_linenum = last_linenum;
  p->last_filename = last_filename;
  p->regno_pointer_flag = regno_pointer_flag;
  p->regno_pointer_flag_length = regno_pointer_flag_length;
  p->regno_reg_rtx = regno_reg_rtx;
}

/* Restore all variables describing the current status from the structure *P.
   This is used after a nested function.  */

void
restore_emit_status (p)
     struct function *p;
{
  int i;

  reg_rtx_no = p->reg_rtx_no;
  first_label_num = p->first_label_num;
  first_insn = p->first_insn;
  last_insn = p->last_insn;
  sequence_stack = p->sequence_stack;
  cur_insn_uid = p->cur_insn_uid;
  last_linenum = p->last_linenum;
  last_filename = p->last_filename;
  regno_pointer_flag = p->regno_pointer_flag;
  regno_pointer_flag_length = p->regno_pointer_flag_length;
  regno_reg_rtx = p->regno_reg_rtx;

  /* Clear our cache of rtx expressions for start_sequence and gen_sequence. */
  sequence_element_free_list = 0;
  for (i = 0; i < SEQUENCE_RESULT_SIZE; i++)
    sequence_result[i] = 0;
}

/* Go through all the RTL insn bodies and copy any invalid shared structure.
   It does not work to do this twice, because the mark bits set here
   are not cleared afterwards.  */

void
unshare_all_rtl (insn)
     register rtx insn;
{
  for (; insn; insn = NEXT_INSN (insn))
    if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
	|| GET_CODE (insn) == CALL_INSN)
      {
	PATTERN (insn) = copy_rtx_if_shared (PATTERN (insn));
	REG_NOTES (insn) = copy_rtx_if_shared (REG_NOTES (insn));
	LOG_LINKS (insn) = copy_rtx_if_shared (LOG_LINKS (insn));
      }

  /* Make sure the addresses of stack slots found outside the insn chain
     (such as, in DECL_RTL of a variable) are not shared
     with the insn chain.

     This special care is necessary when the stack slot MEM does not
     actually appear in the insn chain.  If it does appear, its address
     is unshared from all else at that point.  */

  copy_rtx_if_shared (stack_slot_list);
}

/* Mark ORIG as in use, and return a copy of it if it was already in use.
   Recursively does the same for subexpressions.  */

rtx
copy_rtx_if_shared (orig)
     rtx orig;
{
  register rtx x = orig;
  register int i;
  register enum rtx_code code;
  register char *format_ptr;
  int copied = 0;

  if (x == 0)
    return 0;

  code = GET_CODE (x);

  /* These types may be freely shared.  */

  switch (code)
    {
    case REG:
    case QUEUED:
    case CONST_INT:
    case CONST_DOUBLE:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case SCRATCH:
      /* SCRATCH must be shared because they represent distinct values. */
      return x;

    case INSN:
    case JUMP_INSN:
    case CALL_INSN:
    case NOTE:
    case LABEL_REF:
    case BARRIER:
      /* The chain of insns is not being copied.  */
      return x;

    case MEM:
      /* A MEM is allowed to be shared if its address is constant
	 or is a constant plus one of the special registers.  */
      if (CONSTANT_ADDRESS_P (XEXP (x, 0))
	  || XEXP (x, 0) == virtual_stack_vars_rtx
	  || XEXP (x, 0) == virtual_incoming_args_rtx)
	return x;

      if (GET_CODE (XEXP (x, 0)) == PLUS
	  && (XEXP (XEXP (x, 0), 0) == virtual_stack_vars_rtx
	      || XEXP (XEXP (x, 0), 0) == virtual_incoming_args_rtx)
	  && CONSTANT_ADDRESS_P (XEXP (XEXP (x, 0), 1)))
	{
	  /* This MEM can appear in more than one place,
	     but its address better not be shared with anything else.  */
	  if (! x->used)
	    XEXP (x, 0) = copy_rtx_if_shared (XEXP (x, 0));
	  x->used = 1;
	  return x;
	}
    }

  /* This rtx may not be shared.  If it has already been seen,
     replace it with a copy of itself.  */

  if (x->used)
    {
      register rtx copy;

      copy = rtx_alloc (code);
      bcopy (x, copy, (sizeof (*copy) - sizeof (copy->fld)
		       + sizeof (copy->fld[0]) * GET_RTX_LENGTH (code)));
      x = copy;
      copied = 1;
    }
  x->used = 1;

  /* Now scan the subexpressions recursively.
     We can store any replaced subexpressions directly into X
     since we know X is not shared!  Any vectors in X
     must be copied if X was copied.  */

  format_ptr = GET_RTX_FORMAT (code);

  for (i = 0; i < GET_RTX_LENGTH (code); i++)
    {
      switch (*format_ptr++)
	{
	case 'e':
	  XEXP (x, i) = copy_rtx_if_shared (XEXP (x, i));
	  break;

	case 'E':
	  if (XVEC (x, i) != NULL)
	    {
	      register int j;

	      if (copied)
		XVEC (x, i) = gen_rtvec_v (XVECLEN (x, i), &XVECEXP (x, i, 0));
	      for (j = 0; j < XVECLEN (x, i); j++)
		XVECEXP (x, i, j)
		  = copy_rtx_if_shared (XVECEXP (x, i, j));
	    }
	  break;
	}
    }
  return x;
}

/* Clear all the USED bits in X to allow copy_rtx_if_shared to be used
   to look for shared sub-parts.  */

void
reset_used_flags (x)
     rtx x;
{
  register int i, j;
  register enum rtx_code code;
  register char *format_ptr;
  int copied = 0;

  if (x == 0)
    return;

  code = GET_CODE (x);

  /* These types may be freely shared so we needn't do any reseting
     for them.  */

  switch (code)
    {
    case REG:
    case QUEUED:
    case CONST_INT:
    case CONST_DOUBLE:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
      return;

    case INSN:
    case JUMP_INSN:
    case CALL_INSN:
    case NOTE:
    case LABEL_REF:
    case BARRIER:
      /* The chain of insns is not being copied.  */
      return;
    }

  x->used = 0;

  format_ptr = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++)
    {
      switch (*format_ptr++)
	{
	case 'e':
	  reset_used_flags (XEXP (x, i));
	  break;

	case 'E':
	  for (j = 0; j < XVECLEN (x, i); j++)
	    reset_used_flags (XVECEXP (x, i, j));
	  break;
	}
    }
}

/* Copy X if necessary so that it won't be altered by changes in OTHER.
   Return X or the rtx for the pseudo reg the value of X was copied into.
   OTHER must be valid as a SET_DEST.  */

rtx
make_safe_from (x, other)
     rtx x, other;
{
  while (1)
    switch (GET_CODE (other))
      {
      case SUBREG:
	other = SUBREG_REG (other);
	break;
      case STRICT_LOW_PART:
      case SIGN_EXTEND:
      case ZERO_EXTEND:
	other = XEXP (other, 0);
	break;
      default:
	goto done;
      }
 done:
  if ((GET_CODE (other) == MEM
       && ! CONSTANT_P (x)
       && GET_CODE (x) != REG
       && GET_CODE (x) != SUBREG)
      || (GET_CODE (other) == REG
	  && (REGNO (other) < FIRST_PSEUDO_REGISTER
	      || reg_mentioned_p (other, x))))
    {
      rtx temp = gen_reg_rtx (GET_MODE (x));
      emit_move_insn (temp, x);
      return temp;
    }
  return x;
}

/* Emission of insns (adding them to the doubly-linked list).  */

/* Return the first insn of the current sequence or current function.  */

rtx
get_insns ()
{
  return first_insn;
}

/* Return the last insn emitted in current sequence or current function.  */

rtx
get_last_insn ()
{
  return last_insn;
}

/* Specify a new insn as the last in the chain.  */

void
set_last_insn (insn)
     rtx insn;
{