sparc.c

gcc库的原代码,对编程有很大帮助.

	  case CCXmode :
	  case CCFPEmode :
	  case CCFPmode :
	    break;
	  default :
	    abort ();
	}
	emit_insn (gen_rtx (SET, VOIDmode, operands[0], const0_rtx));
	emit_insn (gen_rtx (SET, VOIDmode, operands[0],
			    gen_rtx (IF_THEN_ELSE, VOIDmode,
				     gen_rtx (compare_code,
					      GET_MODE (operands[1]),
					      operands[1], const0_rtx),
					      const1_rtx, operands[0])));
	return 1;
    }
}

/* Emit a conditional jump insn for the v9 architecture using comparison code
   CODE and jump target LABEL.
   This function exists to take advantage of the v9 brxx insns.  */

void
emit_v9_brxx_insn (code, op0, label)
     enum rtx_code code;
     rtx op0, label;
{
  emit_jump_insn (gen_rtx (SET, VOIDmode,
			   pc_rtx,
			   gen_rtx (IF_THEN_ELSE, VOIDmode,
				    gen_rtx (code, GET_MODE (op0),
					     op0, const0_rtx),
				    gen_rtx (LABEL_REF, VOIDmode, label),
				    pc_rtx)));
}

/* Return nonzero if a return peephole merging return with
   setting of output register is ok.  */
int
leaf_return_peephole_ok ()
{
  return (actual_fsize == 0);
}

/* Return nonzero if TRIAL can go into the function epilogue's
   delay slot.  SLOT is the slot we are trying to fill.  */

int
eligible_for_epilogue_delay (trial, slot)
     rtx trial;
     int slot;
{
  rtx pat, src;

  if (slot >= 1)
    return 0;
  if (GET_CODE (trial) != INSN
      || GET_CODE (PATTERN (trial)) != SET)
    return 0;
  if (get_attr_length (trial) != 1)
    return 0;

  /* In the case of a true leaf function, anything can go into the delay slot.
     A delay slot only exists however if the frame size is zero, otherwise
     we will put an insn to adjust the stack after the return.  */
  if (leaf_function)
    {
      if (leaf_return_peephole_ok ())
	return (get_attr_in_uncond_branch_delay (trial) == IN_BRANCH_DELAY_TRUE);
      return 0;
    }

  /* Otherwise, only operations which can be done in tandem with
     a `restore' insn can go into the delay slot.  */
  pat = PATTERN (trial);
  if (GET_CODE (SET_DEST (pat)) != REG
      || REGNO (SET_DEST (pat)) == 0
      || REGNO (SET_DEST (pat)) >= 32
      || REGNO (SET_DEST (pat)) < 24)
    return 0;

  src = SET_SRC (pat);
  if (arith_operand (src, GET_MODE (src)))
    return GET_MODE_SIZE (GET_MODE (src)) <= GET_MODE_SIZE (SImode);
  if (arith_double_operand (src, GET_MODE (src)))
    return GET_MODE_SIZE (GET_MODE (src)) <= GET_MODE_SIZE (DImode);
  if (GET_CODE (src) == PLUS)
    {
      if (register_operand (XEXP (src, 0), SImode)
	  && arith_operand (XEXP (src, 1), SImode))
	return 1;
      if (register_operand (XEXP (src, 1), SImode)
	  && arith_operand (XEXP (src, 0), SImode))
	return 1;
      if (register_operand (XEXP (src, 0), DImode)
	  && arith_double_operand (XEXP (src, 1), DImode))
	return 1;
      if (register_operand (XEXP (src, 1), DImode)
	  && arith_double_operand (XEXP (src, 0), DImode))
	return 1;
    }
  if (GET_CODE (src) == MINUS
      && register_operand (XEXP (src, 0), SImode)
      && small_int (XEXP (src, 1), VOIDmode))
    return 1;
  if (GET_CODE (src) == MINUS
      && register_operand (XEXP (src, 0), DImode)
      && !register_operand (XEXP (src, 1), DImode)
      && arith_double_operand (XEXP (src, 1), DImode))
    return 1;
  return 0;
}

int
short_branch (uid1, uid2)
     int uid1, uid2;
{
  unsigned int delta = insn_addresses[uid1] - insn_addresses[uid2];
  if (delta + 1024 < 2048)
    return 1;
  /* warning ("long branch, distance %d", delta); */
  return 0;
}

/* Return non-zero if REG is not used after INSN.
   We assume REG is a reload reg, and therefore does
   not live past labels or calls or jumps.  */
int
reg_unused_after (reg, insn)
     rtx reg;
     rtx insn;
{
  enum rtx_code code, prev_code = UNKNOWN;

  while (insn = NEXT_INSN (insn))
    {
      if (prev_code == CALL_INSN && call_used_regs[REGNO (reg)])
	return 1;

      code = GET_CODE (insn);
      if (GET_CODE (insn) == CODE_LABEL)
	return 1;

      if (GET_RTX_CLASS (code) == 'i')
	{
	  rtx set = single_set (insn);
	  int in_src = set && reg_overlap_mentioned_p (reg, SET_SRC (set));
	  if (set && in_src)
	    return 0;
	  if (set && reg_overlap_mentioned_p (reg, SET_DEST (set)))
	    return 1;
	  if (set == 0 && reg_overlap_mentioned_p (reg, PATTERN (insn)))
	    return 0;
	}
      prev_code = code;
    }
  return 1;
}

/* The rtx for the global offset table which is a special form
   that *is* a position independent symbolic constant.  */
static rtx pic_pc_rtx;

/* Ensure that we are not using patterns that are not OK with PIC.  */

int
check_pic (i)
     int i;
{
  switch (flag_pic)
    {
    case 1:
      if (GET_CODE (recog_operand[i]) == SYMBOL_REF
	  || (GET_CODE (recog_operand[i]) == CONST
	      && ! rtx_equal_p (pic_pc_rtx, recog_operand[i])))
	abort ();
    case 2:
    default:
      return 1;
    }
}

/* Return true if X is an address which needs a temporary register when 
   reloaded while generating PIC code.  */

int
pic_address_needs_scratch (x)
     rtx x;
{
  /* An address which is a symbolic plus a non SMALL_INT needs a temp reg.  */
  if (GET_CODE (x) == CONST && GET_CODE (XEXP (x, 0)) == PLUS
      && GET_CODE (XEXP (XEXP (x, 0), 0)) == SYMBOL_REF
      && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
      && ! SMALL_INT (XEXP (XEXP (x, 0), 1)))
    return 1;

  return 0;
}

/* Legitimize PIC addresses.  If the address is already position-independent,
   we return ORIG.  Newly generated position-independent addresses go into a
   reg.  This is REG if non zero, otherwise we allocate register(s) as
   necessary.  */

rtx
legitimize_pic_address (orig, mode, reg)
     rtx orig;
     enum machine_mode mode;
     rtx reg;
{
  if (GET_CODE (orig) == SYMBOL_REF)
    {
      rtx pic_ref, address;
      rtx insn;

      if (reg == 0)
	{
	  if (reload_in_progress || reload_completed)
	    abort ();
	  else
	    reg = gen_reg_rtx (Pmode);
	}

      if (flag_pic == 2)
	{
	  /* If not during reload, allocate another temp reg here for loading
	     in the address, so that these instructions can be optimized
	     properly.  */
	  rtx temp_reg = ((reload_in_progress || reload_completed)
			  ? reg : gen_reg_rtx (Pmode));

	  /* Must put the SYMBOL_REF inside an UNSPEC here so that cse
	     won't get confused into thinking that these two instructions
	     are loading in the true address of the symbol.  If in the
	     future a PIC rtx exists, that should be used instead.  */
	  emit_insn (gen_rtx (SET, VOIDmode, temp_reg,
			      gen_rtx (HIGH, Pmode,
				       gen_rtx (UNSPEC, Pmode,
						gen_rtvec (1, orig),
						0))));
	  emit_insn (gen_rtx (SET, VOIDmode, temp_reg,
			      gen_rtx (LO_SUM, Pmode, temp_reg,
				       gen_rtx (UNSPEC, Pmode,
						gen_rtvec (1, orig),
						0))));
	  address = temp_reg;
	}
      else
	address = orig;

      pic_ref = gen_rtx (MEM, Pmode,
			 gen_rtx (PLUS, Pmode,
				  pic_offset_table_rtx, address));
      current_function_uses_pic_offset_table = 1;
      RTX_UNCHANGING_P (pic_ref) = 1;
      insn = emit_move_insn (reg, pic_ref);
      /* Put a REG_EQUAL note on this insn, so that it can be optimized
	 by loop.  */
      REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_EQUAL, orig,
				  REG_NOTES (insn));
      return reg;
    }
  else if (GET_CODE (orig) == CONST)
    {
      rtx base, offset;

      if (GET_CODE (XEXP (orig, 0)) == PLUS
	  && XEXP (XEXP (orig, 0), 0) == pic_offset_table_rtx)
	return orig;

      if (reg == 0)
	{
	  if (reload_in_progress || reload_completed)
	    abort ();
	  else
	    reg = gen_reg_rtx (Pmode);
	}

      if (GET_CODE (XEXP (orig, 0)) == PLUS)
	{
	  base = legitimize_pic_address (XEXP (XEXP (orig, 0), 0), Pmode, reg);
	  offset = legitimize_pic_address (XEXP (XEXP (orig, 0), 1), Pmode,
					 base == reg ? 0 : reg);
	}
      else
	abort ();

      if (GET_CODE (offset) == CONST_INT)
	{
	  if (SMALL_INT (offset))
	    return plus_constant_for_output (base, INTVAL (offset));
	  else if (! reload_in_progress && ! reload_completed)
	    offset = force_reg (Pmode, offset);
	  else
	    /* If we reach here, then something is seriously wrong.  */
	    abort ();
	}
      return gen_rtx (PLUS, Pmode, base, offset);
    }
  else if (GET_CODE (orig) == LABEL_REF)
    current_function_uses_pic_offset_table = 1;

  return orig;
}

/* Set up PIC-specific rtl.  This should not cause any insns
   to be emitted.  */

void
initialize_pic ()
{
}

/* Emit special PIC prologues and epilogues.  */

void
finalize_pic ()
{
  /* The table we use to reference PIC data.  */
  rtx global_offset_table;
  /* Labels to get the PC in the prologue of this function.  */
  rtx l1, l2;
  rtx seq;
  int orig_flag_pic = flag_pic;

  if (current_function_uses_pic_offset_table == 0)
    return;

  if (! flag_pic)
    abort ();

  flag_pic = 0;
  l1 = gen_label_rtx ();
  l2 = gen_label_rtx ();

  start_sequence ();

  emit_label (l1);
  /* Note that we pun calls and jumps here!  */
  emit_jump_insn (gen_rtx (PARALLEL, VOIDmode,
                         gen_rtvec (2,
                                    gen_rtx (SET, VOIDmode, pc_rtx, gen_rtx (LABEL_REF, VOIDmode, l2)),
                                    gen_rtx (SET, VOIDmode, gen_rtx (REG, SImode, 15), gen_rtx (LABEL_REF, VOIDmode, l2)))));
  emit_label (l2);

  /* Initialize every time through, since we can't easily
     know this to be permanent.  */
  global_offset_table = gen_rtx (SYMBOL_REF, Pmode, "_GLOBAL_OFFSET_TABLE_");
  pic_pc_rtx = gen_rtx (CONST, Pmode,
			gen_rtx (MINUS, Pmode,
				 global_offset_table,
				 gen_rtx (CONST, Pmode,
					  gen_rtx (MINUS, Pmode,
						   gen_rtx (LABEL_REF, VOIDmode, l1),
						   pc_rtx))));

  if (Pmode == DImode)
    emit_insn (gen_rtx (PARALLEL, VOIDmode,
			gen_rtvec (2,
				   gen_rtx (SET, VOIDmode, pic_offset_table_rtx,
					    gen_rtx (HIGH, Pmode, pic_pc_rtx)),
				   gen_rtx (CLOBBER, VOIDmode, gen_rtx (REG, Pmode, 1)))));
  else
    emit_insn (gen_rtx (SET, VOIDmode, pic_offset_table_rtx,
			gen_rtx (HIGH, Pmode, pic_pc_rtx)));

  emit_insn (gen_rtx (SET, VOIDmode,
		      pic_offset_table_rtx,
		      gen_rtx (LO_SUM, Pmode,
			       pic_offset_table_rtx, pic_pc_rtx)));
  emit_insn (gen_rtx (SET, VOIDmode,
		      pic_offset_table_rtx,
		      gen_rtx (PLUS, Pmode,
			       pic_offset_table_rtx, gen_rtx (REG, Pmode, 15))));
  /* emit_insn (gen_rtx (ASM_INPUT, VOIDmode, "!#PROLOGUE# 1")); */
  LABEL_PRESERVE_P (l1) = 1;
  LABEL_PRESERVE_P (l2) = 1;
  flag_pic = orig_flag_pic;

  seq = gen_sequence ();
  end_sequence ();
  emit_insn_after (seq, get_insns ());

  /* Need to emit this whether or not we obey regdecls,
     since setjmp/longjmp can cause life info to screw up.  */
  emit_insn (gen_rtx (USE, VOIDmode, pic_offset_table_rtx));
}

/* Emit insns to move operands[1] into operands[0].

   Return 1 if we have written out everything that needs to be done to
   do the move.  Otherwise, return 0 and the caller will emit the move
   normally.  */

int
emit_move_sequence (operands, mode)
     rtx *operands;
     enum machine_mode mode;
{
  register rtx operand0 = operands[0];
  register rtx operand1 = operands[1];

  if (CONSTANT_P (operand1) && flag_pic
      && pic_address_needs_scratch (operand1))
    operands[1] = operand1 = legitimize_pic_address (operand1, mode, 0);

  /* Handle most common case first: storing into a register.  */
  if (register_operand (operand0, mode))
    {
      if (register_operand (operand1, mode)
	  || (GET_CODE (operand1) == CONST_INT && SMALL_INT (operand1))
	  || (GET_CODE (operand1) == CONST_DOUBLE
	      && arith_double_operand (operand1, DImode))
	  || (GET_CODE (operand1) == HIGH && GET_MODE (operand1) != DImode)
	  /* Only `general_operands' can come here, so MEM is ok.  */
	  || GET_CODE (operand1) == MEM)
	{
	  /* Run this case quickly.  */
	  emit_insn (gen_rtx (SET, VOIDmode, operand0, operand1));
	  return 1;
	}
    }
  else if (GET_CODE (operand0) == MEM)
    {
      if (register_operand (operand1, mode) || operand1 == const0_rtx)
	{
	  /* Run this case quickly.  */
	  emit_insn (gen_rtx (SET, VOIDmode, operand0, operand1));
	  return 1;
	}
      if (! reload_in_progress)
	{
	  operands[0] = validize_mem (operand0);
	  operands[1] = operand1 = force_reg (mode, operand1);
	}
    }

  /* Simplify the source if we need to.  Must handle DImode HIGH operators
     here because such a move needs a clobber added.  */
  if ((GET_CODE (operand1) != HIGH && immediate_operand (operand1, mode))
      || (GET_CODE (operand1) == HIGH && GET_MODE (operand1) == DImode))
    {
      if (flag_pic && symbolic_operand (operand1, mode))
	{
	  rtx temp_reg = reload_in_progress ? operand0 : 0;

	  operands[1] = legitimize_pic_address (operand1, mode, temp_reg);
	}
      else if (GET_CODE (operand1) == CONST_INT
	       ? (! SMALL_INT (operand1)
		  && (INTVAL (operand1) & 0x3ff) != 0)
	       : (GET_CODE (operand1) == CONST_DOUBLE
		  ? ! arith_double_operand (operand1, DImode)
		  : 1))
	{
	  /* For DImode values, temp must be operand0 because of the way
	     HI and LO_SUM work.  The LO_SUM operator only copies half of
	     the LSW from the dest of the HI operator.  If the LO_SUM dest is