arm.c

这是一个linux 嵌入式系统中很重要的GCC编译器程序

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;
      int subregs = 0;

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

	  subregs = 1;
	}

#ifdef AOF_ASSEMBLER
      /* The AOF assembler can generate relocations for these directly, and
	 understands that the PIC register has to be added into the offset.
	 */
      insn = emit_insn (gen_pic_load_addr_based (reg, orig));
#else
      if (subregs)
	address = gen_reg_rtx (Pmode);
      else
	address = reg;

      emit_insn (gen_pic_load_addr (address, orig));

      pic_ref = gen_rtx_MEM (Pmode,
			     gen_rtx_PLUS (Pmode, pic_offset_table_rtx,
					   address));
      RTX_UNCHANGING_P (pic_ref) = 1;
      insn = emit_move_insn (reg, pic_ref);
#endif
      current_function_uses_pic_offset_table = 1;
      /* 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)
	{
	  /* The base register doesn't really matter, we only want to
	     test the index for the appropriate mode.  */
	  GO_IF_LEGITIMATE_INDEX (mode, 0, offset, win);

	  if (! reload_in_progress && ! reload_completed)
	    offset = force_reg (Pmode, offset);
	  else
	    abort ();

	win:
	  if (GET_CODE (offset) == CONST_INT)
	    return plus_constant_for_output (base, INTVAL (offset));
	}

      if (GET_MODE_SIZE (mode) > 4
	  && (GET_MODE_CLASS (mode) == MODE_INT
	      || TARGET_SOFT_FLOAT))
	{
	  emit_insn (gen_addsi3 (reg, base, offset));
	  return reg;
	}

      return gen_rtx_PLUS (Pmode, base, offset);
    }
  else if (GET_CODE (orig) == LABEL_REF)
    current_function_uses_pic_offset_table = 1;

  return orig;
}

static rtx pic_rtx;

int
is_pic(x)
     rtx x;
{
  if (x == pic_rtx)
    return 1;
  return 0;
}

void
arm_finalize_pic ()
{
#ifndef AOF_ASSEMBLER
  rtx l1, pic_tmp, pic_tmp2, seq;
  rtx global_offset_table;

  if (current_function_uses_pic_offset_table == 0)
    return;

  if (! flag_pic)
    abort ();

  start_sequence ();
  l1 = gen_label_rtx ();

  global_offset_table = gen_rtx_SYMBOL_REF (Pmode, "_GLOBAL_OFFSET_TABLE_");
  /* On the ARM the PC register contains 'dot + 8' at the time of the
     addition.  */
  pic_tmp = plus_constant (gen_rtx_LABEL_REF (Pmode, l1), 8);
  if (GOT_PCREL)
    pic_tmp2 = gen_rtx_CONST (VOIDmode,
			    gen_rtx_PLUS (Pmode, global_offset_table, pc_rtx));
  else
    pic_tmp2 = gen_rtx_CONST (VOIDmode, global_offset_table);

  pic_rtx = gen_rtx_CONST (Pmode, gen_rtx_MINUS (Pmode, pic_tmp2, pic_tmp));
  
  emit_insn (gen_pic_load_addr (pic_offset_table_rtx, pic_rtx));
  emit_insn (gen_pic_add_dot_plus_eight (pic_offset_table_rtx, l1));

  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));
#endif /* AOF_ASSEMBLER */
}

#define REG_OR_SUBREG_REG(X)						\
  (GET_CODE (X) == REG							\
   || (GET_CODE (X) == SUBREG && GET_CODE (SUBREG_REG (X)) == REG))

#define REG_OR_SUBREG_RTX(X)			\
   (GET_CODE (X) == REG ? (X) : SUBREG_REG (X))

#define ARM_FRAME_RTX(X)				\
  ((X) == frame_pointer_rtx || (X) == stack_pointer_rtx	\
   || (X) == arg_pointer_rtx)

int
arm_rtx_costs (x, code)
     rtx x;
     enum rtx_code code;
{
  enum machine_mode mode = GET_MODE (x);
  enum rtx_code subcode;
  int extra_cost;

  switch (code)
    {
    case MEM:
      /* Memory costs quite a lot for the first word, but subsequent words
	 load at the equivalent of a single insn each.  */
      return (10 + 4 * ((GET_MODE_SIZE (mode) - 1) / UNITS_PER_WORD)
	      + (CONSTANT_POOL_ADDRESS_P (x) ? 4 : 0));

    case DIV:
    case MOD:
      return 100;

    case ROTATE:
      if (mode == SImode && GET_CODE (XEXP (x, 1)) == REG)
	return 4;
      /* Fall through */
    case ROTATERT:
      if (mode != SImode)
	return 8;
      /* Fall through */
    case ASHIFT: case LSHIFTRT: case ASHIFTRT:
      if (mode == DImode)
	return (8 + (GET_CODE (XEXP (x, 1)) == CONST_INT ? 0 : 8)
		+ ((GET_CODE (XEXP (x, 0)) == REG 
		    || (GET_CODE (XEXP (x, 0)) == SUBREG
			&& GET_CODE (SUBREG_REG (XEXP (x, 0))) == REG))
		   ? 0 : 8));
      return (1 + ((GET_CODE (XEXP (x, 0)) == REG
		    || (GET_CODE (XEXP (x, 0)) == SUBREG
			&& GET_CODE (SUBREG_REG (XEXP (x, 0))) == REG))
		   ? 0 : 4)
	      + ((GET_CODE (XEXP (x, 1)) == REG
		  || (GET_CODE (XEXP (x, 1)) == SUBREG
		      && GET_CODE (SUBREG_REG (XEXP (x, 1))) == REG)
		  || (GET_CODE (XEXP (x, 1)) == CONST_INT))
		 ? 0 : 4));

    case MINUS:
      if (mode == DImode)
	return (4 + (REG_OR_SUBREG_REG (XEXP (x, 1)) ? 0 : 8)
		+ ((REG_OR_SUBREG_REG (XEXP (x, 0))
		    || (GET_CODE (XEXP (x, 0)) == CONST_INT
		       && const_ok_for_arm (INTVAL (XEXP (x, 0)))))
		   ? 0 : 8));

      if (GET_MODE_CLASS (mode) == MODE_FLOAT)
	return (2 + ((REG_OR_SUBREG_REG (XEXP (x, 1))
		      || (GET_CODE (XEXP (x, 1)) == CONST_DOUBLE
			  && const_double_rtx_ok_for_fpu (XEXP (x, 1))))
		     ? 0 : 8)
		+ ((REG_OR_SUBREG_REG (XEXP (x, 0))
		    || (GET_CODE (XEXP (x, 0)) == CONST_DOUBLE
			&& const_double_rtx_ok_for_fpu (XEXP (x, 0))))
		   ? 0 : 8));

      if (((GET_CODE (XEXP (x, 0)) == CONST_INT
	    && const_ok_for_arm (INTVAL (XEXP (x, 0)))
	    && REG_OR_SUBREG_REG (XEXP (x, 1))))
	  || (((subcode = GET_CODE (XEXP (x, 1))) == ASHIFT
	       || subcode == ASHIFTRT || subcode == LSHIFTRT
	       || subcode == ROTATE || subcode == ROTATERT
	       || (subcode == MULT
		   && GET_CODE (XEXP (XEXP (x, 1), 1)) == CONST_INT
		   && ((INTVAL (XEXP (XEXP (x, 1), 1)) &
			(INTVAL (XEXP (XEXP (x, 1), 1)) - 1)) == 0)))
	      && REG_OR_SUBREG_REG (XEXP (XEXP (x, 1), 0))
	      && (REG_OR_SUBREG_REG (XEXP (XEXP (x, 1), 1))
		  || GET_CODE (XEXP (XEXP (x, 1), 1)) == CONST_INT)
	      && REG_OR_SUBREG_REG (XEXP (x, 0))))
	return 1;
      /* Fall through */

    case PLUS: 
      if (GET_MODE_CLASS (mode) == MODE_FLOAT)
	return (2 + (REG_OR_SUBREG_REG (XEXP (x, 0)) ? 0 : 8)
		+ ((REG_OR_SUBREG_REG (XEXP (x, 1))
		    || (GET_CODE (XEXP (x, 1)) == CONST_DOUBLE
			&& const_double_rtx_ok_for_fpu (XEXP (x, 1))))
		   ? 0 : 8));

      /* Fall through */
    case AND: case XOR: case IOR: 
      extra_cost = 0;

      /* Normally the frame registers will be spilt into reg+const during
	 reload, so it is a bad idea to combine them with other instructions,
	 since then they might not be moved outside of loops.  As a compromise
	 we allow integration with ops that have a constant as their second
	 operand.  */
      if ((REG_OR_SUBREG_REG (XEXP (x, 0))
	   && ARM_FRAME_RTX (REG_OR_SUBREG_RTX (XEXP (x, 0)))
	   && GET_CODE (XEXP (x, 1)) != CONST_INT)
	  || (REG_OR_SUBREG_REG (XEXP (x, 0))
	      && ARM_FRAME_RTX (REG_OR_SUBREG_RTX (XEXP (x, 0)))))
	extra_cost = 4;

      if (mode == DImode)
	return (4 + extra_cost + (REG_OR_SUBREG_REG (XEXP (x, 0)) ? 0 : 8)
		+ ((REG_OR_SUBREG_REG (XEXP (x, 1))
		    || (GET_CODE (XEXP (x, 1)) == CONST_INT
			&& const_ok_for_op (INTVAL (XEXP (x, 1)), code)))
		   ? 0 : 8));

      if (REG_OR_SUBREG_REG (XEXP (x, 0)))
	return (1 + (GET_CODE (XEXP (x, 1)) == CONST_INT ? 0 : extra_cost)
		+ ((REG_OR_SUBREG_REG (XEXP (x, 1))
		    || (GET_CODE (XEXP (x, 1)) == CONST_INT
			&& const_ok_for_op (INTVAL (XEXP (x, 1)), code)))
		   ? 0 : 4));

      else if (REG_OR_SUBREG_REG (XEXP (x, 1)))
	return (1 + extra_cost
		+ ((((subcode = GET_CODE (XEXP (x, 0))) == ASHIFT
		     || subcode == LSHIFTRT || subcode == ASHIFTRT
		     || subcode == ROTATE || subcode == ROTATERT
		     || (subcode == MULT
			 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
			 && ((INTVAL (XEXP (XEXP (x, 0), 1)) &
			      (INTVAL (XEXP (XEXP (x, 0), 1)) - 1)) == 0)))
		    && (REG_OR_SUBREG_REG (XEXP (XEXP (x, 0), 0)))
		    && ((REG_OR_SUBREG_REG (XEXP (XEXP (x, 0), 1)))
			|| GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT))
		   ? 0 : 4));

      return 8;

    case MULT:
      /* There is no point basing this on the tuning, since it is always the
	 fast variant if it exists at all */
      if (arm_fast_multiply && mode == DImode
	  && (GET_CODE (XEXP (x, 0)) == GET_CODE (XEXP (x, 1)))
	  && (GET_CODE (XEXP (x, 0)) == ZERO_EXTEND
	      || GET_CODE (XEXP (x, 0)) == SIGN_EXTEND))
	return 8;

      if (GET_MODE_CLASS (mode) == MODE_FLOAT
	  || mode == DImode)
	return 30;

      if (GET_CODE (XEXP (x, 1)) == CONST_INT)
	{
	  unsigned HOST_WIDE_INT i = (INTVAL (XEXP (x, 1))
				      & (unsigned HOST_WIDE_INT) 0xffffffff);
	  int add_cost = const_ok_for_arm (i) ? 4 : 8;
	  int j;
	  /* Tune as appropriate */ 
	  int booth_unit_size = ((tune_flags & FL_FAST_MULT) ? 8 : 2);
	  
	  for (j = 0; i && j < 32; j += booth_unit_size)
	    {
	      i >>= booth_unit_size;
	      add_cost += 2;
	    }

	  return add_cost;
	}

      return (((tune_flags & FL_FAST_MULT) ? 8 : 30)
	      + (REG_OR_SUBREG_REG (XEXP (x, 0)) ? 0 : 4)
	      + (REG_OR_SUBREG_REG (XEXP (x, 1)) ? 0 : 4));

    case TRUNCATE:
      if (arm_fast_multiply && mode == SImode
	  && GET_CODE (XEXP (x, 0)) == LSHIFTRT
	  && GET_CODE (XEXP (XEXP (x, 0), 0)) == MULT
	  && (GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0))
	      == GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)))
	  && (GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == ZERO_EXTEND
	      || GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == SIGN_EXTEND))
	return 8;
      return 99;

    case NEG:
      if (GET_MODE_CLASS (mode) == MODE_FLOAT)
	return 4 + (REG_OR_SUBREG_REG (XEXP (x, 0)) ? 0 : 6);
      /* Fall through */
    case NOT:
      if (mode == DImode)
	return 4 + (REG_OR_SUBREG_REG (XEXP (x, 0)) ? 0 : 4);

      return 1 + (REG_OR_SUBREG_REG (XEXP (x, 0)) ? 0 : 4);

    case IF_THEN_ELSE:
      if (GET_CODE (XEXP (x, 1)) == PC || GET_CODE (XEXP (x, 2)) == PC)
	return 14;
      return 2;

    case COMPARE:
      return 1;

    case ABS:
      return 4 + (mode == DImode ? 4 : 0);

    case SIGN_EXTEND:
      if (GET_MODE (XEXP (x, 0)) == QImode)
	return (4 + (mode == DImode ? 4 : 0)
		+ (GET_CODE (XEXP (x, 0)) == MEM ? 10 : 0));
      /* Fall through */
    case ZERO_EXTEND:
      switch (GET_MODE (XEXP (x, 0)))
	{
	case QImode:
	  return (1 + (mode == DImode ? 4 : 0)
		  + (GET_CODE (XEXP (x, 0)) == MEM ? 10 : 0));

	case HImode:
	  return (4 + (mode == DImode ? 4 : 0)
		  + (GET_CODE (XEXP (x, 0)) == MEM ? 10 : 0));

	case SImode:
	  return (1 + (GET_CODE (XEXP (x, 0)) == MEM ? 10 : 0));

	default:
	  break;
	}
      abort ();

    default:
      return 99;
    }
}

int
arm_adjust_cost (insn, link, dep, cost)
     rtx insn;
     rtx link;
     rtx dep;
     int cost;
{
  rtx i_pat, d_pat;

  /* XXX This is not strictly true for the FPA. */
  if (REG_NOTE_KIND(link) == REG_DEP_ANTI
      || REG_NOTE_KIND(link) == REG_DEP_OUTPUT)
    return 0;

  if ((i_pat = single_set (insn)) != NULL
      && GET_CODE (SET_SRC (i_pat)) == MEM
      && (d_pat = single_set (dep)) != NULL
      && GET_CODE (SET_DEST (d_pat)) == MEM)
    {
      /* This is a load after a store, there is no conflict if the load reads
	 from a cached area.  Assume that loads from the stack, and from the
	 constant pool are cached, and that others will miss.  This is a 
	 hack. */
      
/*       debug_rtx (insn);
      debug_rtx (dep);
      debug_rtx (link);
      fprintf (stderr, "costs %d\n", cost); */

      if (CONSTANT_POOL_ADDRESS_P (XEXP (SET_SRC (i_pat), 0))
	  || reg_mentioned_p (stack_pointer_rtx, XEXP (SET_SRC (i_pat), 0))
	  || reg_mentioned_p (frame_pointer_rtx, XEXP (SET_SRC (i_pat), 0))
	  || reg_mentioned_p (hard_frame_pointer_rtx, 
			      XEXP (SET_SRC (i_pat), 0)))
	{
/* 	  fprintf (stderr, "***** Now 1\n"); */
	  return 1;
	}
    }

  return cost;
}

/* This code has been fixed for cross compilation. */

static int fpa_consts_inited = 0;

char *strings_fpa[8] = {
  "0",   "1",   "2",   "3",
  "4",   "5",   "0.5", "10"
};

static REAL_VALUE_TYPE values_fpa[8];

static void
init_fpa_table ()
{
  int i;
  REAL_VALUE_TYPE r;

  for (i = 0; i < 8; i++)
    {
      r = REAL_VALUE_ATOF (strings_fpa[i], DFmode);
      values_fpa[i] = r;
    }

  fpa_consts_inited = 1;
}

/* Return TRUE if rtx X is a valid immediate FPU constant. */

int
const_double_rtx_ok_for_fpu (x)
     rtx x;
{
  REAL_VALUE_TYPE r;
  int i;