rs6000.c

gcc库的原代码,对编程有很大帮助.

      /* If the high bit is set and the low bit is not, the value is zero.
	 If the high bit is zero, the value is the first 1 bit we find from
	 the left.  */
      if (val < 0 && (val & 1) == 0)
	{
	  fprintf (file, "0");
	  return;
	}
      else if (val >= 0)
	{
	  for (i = 1; i < 32; i++)
	    if ((val <<= 1) < 0)
	      break;
	  fprintf (file, "%d", i);
	  return;
	}
	  
      /* Otherwise, look for the first 0 bit from the right.  The result is its
	 number plus 1. We know the low-order bit is one.  */
      for (i = 0; i < 32; i++)
	if (((val >>= 1) & 1) == 0)
	  break;

      /* If we ended in ...01, I would be 0.  The correct value is 31, so
	 we want 31 - i.  */
      fprintf (file, "%d", 31 - i);
      return;

    case 'M':
      /* ME value for a mask operand.  */
      if (! mask_operand (x, VOIDmode))
	output_operand_lossage ("invalid %%m value");

      val = INT_LOWPART (x);

      /* If the low bit is set and the high bit is not, the value is 31.
	 If the low bit is zero, the value is the first 1 bit we find from
	 the right.  */
      if ((val & 1) && val >= 0)
	{
	  fputs ("31", file);
	  return;
	}
      else if ((val & 1) == 0)
	{
	  for (i = 0; i < 32; i++)
	    if ((val >>= 1) & 1)
	      break;

	  /* If we had ....10, I would be 0.  The result should be
	     30, so we need 30 - i.  */
	  fprintf (file, "%d", 30 - i);
	  return;
	}
	  
      /* Otherwise, look for the first 0 bit from the left.  The result is its
	 number minus 1. We know the high-order bit is one.  */
      for (i = 0; i < 32; i++)
	if ((val <<= 1) >= 0)
	  break;

      fprintf (file, "%d", i);
      return;

    case 'N':
      /* Write the number of elements in the vector times 4.  */
      if (GET_CODE (x) != PARALLEL)
	output_operand_lossage ("invalid %%N value");

      fprintf (file, "%d", XVECLEN (x, 0) * 4);
      return;

    case 'O':
      /* Similar, but subtract 1 first.  */
      if (GET_CODE (x) != PARALLEL)
	output_operand_lossage ("invalid %%N value");

      fprintf (file, "%d", (XVECLEN (x, 0) - 1) * 4);
      return;

    case 'p':
      /* X is a CONST_INT that is a power of two.  Output the logarithm.  */
      if (! INT_P (x)
	  || (i = exact_log2 (INT_LOWPART (x))) < 0)
	output_operand_lossage ("invalid %%p value");

      fprintf (file, "%d", i);
      return;

    case 'P':
      /* The operand must be an indirect memory reference.  The result
	 is the register number. */
      if (GET_CODE (x) != MEM || GET_CODE (XEXP (x, 0)) != REG
	  || REGNO (XEXP (x, 0)) >= 32)
	output_operand_lossage ("invalid %%P value");

      fprintf (file, "%d", REGNO (XEXP (x, 0)));
      return;

    case 'R':
      /* X is a CR register.  Print the mask for `mtcrf'.  */
      if (GET_CODE (x) != REG || ! CR_REGNO_P (REGNO (x)))
	output_operand_lossage ("invalid %%R value");
      else
	fprintf (file, "%d", 128 >> (REGNO (x) - 68));
      return;

    case 's':
      /* Low 5 bits of 32 - value */
      if (! INT_P (x))
	output_operand_lossage ("invalid %%s value");

      fprintf (file, "%d", (32 - INT_LOWPART (x)) & 31);
      return;

    case 't':
      /* Write 12 if this jump operation will branch if true, 4 otherwise. 
	 All floating-point operations except NE branch true and integer
	 EQ, LT, GT, LTU and GTU also branch true.  */
      if (GET_RTX_CLASS (GET_CODE (x)) != '<')
	output_operand_lossage ("invalid %%t value");

      else if ((GET_MODE (XEXP (x, 0)) == CCFPmode
		&& GET_CODE (x) != NE)
	       || GET_CODE (x) == EQ
	       || GET_CODE (x) == LT || GET_CODE (x) == GT
	       || GET_CODE (x) == LTU || GET_CODE (x) == GTU)
	fputs ("12", file);
      else
	putc ('4', file);
      return;
      
    case 'T':
      /* Opposite of 't': write 4 if this jump operation will branch if true,
	 12 otherwise.   */
      if (GET_RTX_CLASS (GET_CODE (x)) != '<')
	output_operand_lossage ("invalid %%t value");

      else if ((GET_MODE (XEXP (x, 0)) == CCFPmode
		&& GET_CODE (x) != NE)
	       || GET_CODE (x) == EQ
	       || GET_CODE (x) == LT || GET_CODE (x) == GT
	       || GET_CODE (x) == LTU || GET_CODE (x) == GTU)
	putc ('4', file);
      else
	fputs ("12", file);
      return;
      
    case 'u':
      /* High-order 16 bits of constant.  */
      if (! INT_P (x))
	output_operand_lossage ("invalid %%u value");

      fprintf (file, "0x%x", (INT_LOWPART (x) >> 16) & 0xffff);
      return;

    case 'U':
      /* Print `u' if this has an auto-increment or auto-decrement.  */
      if (GET_CODE (x) == MEM
	  && (GET_CODE (XEXP (x, 0)) == PRE_INC
	      || GET_CODE (XEXP (x, 0)) == PRE_DEC))
	putc ('u', file);
      return;

    case 'w':
      /* If constant, low-order 16 bits of constant, signed.  Otherwise, write
	 normally.  */
      if (INT_P (x))
	fprintf (file, "%d",
		 (INT_LOWPART (x) & 0xffff) - 2 * (INT_LOWPART (x) & 0x8000));
      else
	print_operand (file, x, 0);
      return;

    case 'W':
      /* If constant, low-order 16 bits of constant, unsigned.
	 Otherwise, write normally.  */
      if (INT_P (x))
	fprintf (file, "%d", INT_LOWPART (x) & 0xffff);
      else
	print_operand (file, x, 0);
      return;

    case 'X':
      if (GET_CODE (x) == MEM
	  && LEGITIMATE_INDEXED_ADDRESS_P (XEXP (x, 0)))
	putc ('x', file);
      return;

    case 'Y':
      /* Like 'L', for third word of TImode  */
      if (GET_CODE (x) == REG)
	fprintf (file, "%d", REGNO (x) + 2);
      else if (GET_CODE (x) == MEM)
	{
	  if (GET_CODE (XEXP (x, 0)) == PRE_INC
	      || GET_CODE (XEXP (x, 0)) == PRE_DEC)
	    output_address (plus_constant (XEXP (XEXP (x, 0), 0), 8));
	  else
	    output_address (plus_constant (XEXP (x, 0), 8));
	}
      return;
			    
    case 'z':
      /* X is a SYMBOL_REF.  Write out the name preceded by a
	 period and without any trailing data in brackets.  Used for function
	 names.  If we are configured for System V (or the embedded ABI) on
	 the PowerPC, do not emit the period, since those systems do not use
	 TOCs and the like.  */
      if (GET_CODE (x) != SYMBOL_REF)
	abort ();

#ifndef USING_SVR4_H
      putc ('.', file);
#endif
      RS6000_OUTPUT_BASENAME (file, XSTR (x, 0));
      return;

    case 'Z':
      /* Like 'L', for last word of TImode.  */
      if (GET_CODE (x) == REG)
	fprintf (file, "%d", REGNO (x) + 3);
      else if (GET_CODE (x) == MEM)
	{
	  if (GET_CODE (XEXP (x, 0)) == PRE_INC
	      || GET_CODE (XEXP (x, 0)) == PRE_DEC)
	    output_address (plus_constant (XEXP (XEXP (x, 0), 0), 12));
	  else
	    output_address (plus_constant (XEXP (x, 0), 12));
	}
      return;
			    
    case 0:
      if (GET_CODE (x) == REG)
	fprintf (file, "%s", reg_names[REGNO (x)]);
      else if (GET_CODE (x) == MEM)
	{
	  /* We need to handle PRE_INC and PRE_DEC here, since we need to
	     know the width from the mode.  */
	  if (GET_CODE (XEXP (x, 0)) == PRE_INC)
	    fprintf (file, "%d(%d)", GET_MODE_SIZE (GET_MODE (x)),
		     REGNO (XEXP (XEXP (x, 0), 0)));
	  else if (GET_CODE (XEXP (x, 0)) == PRE_DEC)
	    fprintf (file, "%d(%d)", - GET_MODE_SIZE (GET_MODE (x)),
		     REGNO (XEXP (XEXP (x, 0), 0)));
	  else
	    output_address (XEXP (x, 0));
	}
      else
	output_addr_const (file, x);
      return;

    default:
      output_operand_lossage ("invalid %%xn code");
    }
}

/* Print the address of an operand.  */

void
print_operand_address (file, x)
     FILE *file;
     register rtx x;
{
  if (GET_CODE (x) == REG)
    fprintf (file, "0(%s)", reg_names[ REGNO (x) ]);
  else if (GET_CODE (x) == SYMBOL_REF || GET_CODE (x) == CONST)
    {
      output_addr_const (file, x);
      /* When TARGET_MINIMAL_TOC, use the indirected toc table pointer instead
	 of the toc pointer.  */
#ifdef TARGET_NO_TOC
      if (TARGET_NO_TOC)
	;
      else
#endif
	fprintf (file, "(%s)", reg_names[ TARGET_MINIMAL_TOC ? 30 : 2 ]);
    }
  else if (GET_CODE (x) == PLUS && GET_CODE (XEXP (x, 1)) == REG)
    {
      if (REGNO (XEXP (x, 0)) == 0)
	fprintf (file, "%s,%s", reg_names[ REGNO (XEXP (x, 1)) ],
		 reg_names[ REGNO (XEXP (x, 0)) ]);
      else
	fprintf (file, "%s,%s", reg_names[ REGNO (XEXP (x, 0)) ],
		 reg_names[ REGNO (XEXP (x, 1)) ]);
    }
  else if (GET_CODE (x) == PLUS && GET_CODE (XEXP (x, 1)) == CONST_INT)
    fprintf (file, "%d(%s)", INTVAL (XEXP (x, 1)), reg_names[ REGNO (XEXP (x, 0)) ]);
  else if (TARGET_ELF && !TARGET_64BIT && GET_CODE (x) == LO_SUM
	   && GET_CODE (XEXP (x, 0)) == REG && CONSTANT_P (XEXP (x, 1)))
    {
      output_addr_const (file, XEXP (x, 1));
      fprintf (file, "@l(%s)", reg_names[ REGNO (XEXP (x, 0)) ]);
    }
  else
    abort ();
}

/* This page contains routines that are used to determine what the function
   prologue and epilogue code will do and write them out.  */

/*  Return the first fixed-point register that is required to be saved. 32 if
    none.  */

int
first_reg_to_save ()
{
  int first_reg;

  /* Find lowest numbered live register.  */
  for (first_reg = 13; first_reg <= 31; first_reg++)
    if (regs_ever_live[first_reg])
      break;

  /* If profiling, then we must save/restore every register that contains
     a parameter before/after the .mcount call.  Use registers from 30 down
     to 23 to do this.  Don't use the frame pointer in reg 31.

     For now, save enough room for all of the parameter registers.  */
#ifndef USING_SVR4_H
  if (profile_flag)
    if (first_reg > 23)
      first_reg = 23;
#endif

  return first_reg;
}

/* Similar, for FP regs.  */

int
first_fp_reg_to_save ()
{
  int first_reg;

  /* Find lowest numbered live register.  */
  for (first_reg = 14 + 32; first_reg <= 63; first_reg++)
    if (regs_ever_live[first_reg])
      break;

  return first_reg;
}

/* Return non-zero if this function makes calls.  */

int
rs6000_makes_calls ()
{
  rtx insn;

  /* If we are profiling, we will be making a call to mcount.  */
  if (profile_flag)
    return 1;

  for (insn = get_insns (); insn; insn = next_insn (insn))
    if (GET_CODE (insn) == CALL_INSN)
      return 1;

  return 0;
}


/* Calculate the stack information for the current function.  This is
   complicated by having two separate calling sequences, the AIX calling
   sequence and the V.4 calling sequence.

   AIX stack frames look like:

	SP---->	+---------------------------------------+
		| back chain to caller			| 0
		+---------------------------------------+
		| saved CR				| 4
		+---------------------------------------+
		| saved LR				| 8
		+---------------------------------------+
		| reserved for compilers		| 12
		+---------------------------------------+
		| reserved for binders			| 16
		+---------------------------------------+
		| saved TOC pointer			| 20
		+---------------------------------------+
		| Parameter save area (P)		| 24
		+---------------------------------------+
		| Alloca space (A)			| 24+P
		+---------------------------------------+
		| Local variable space (L)		| 24+P+A
		+---------------------------------------+
		| Save area for GP registers (G)	| 24+P+A+L
		+---------------------------------------+
		| Save area for FP registers (F)	| 24+P+A+L+G
		+---------------------------------------+
	old SP->| back chain to caller's caller		|
		+---------------------------------------+

   V.4 stack frames look like:

	SP---->	+---------------------------------------+
		| back chain to caller			| 0
		+---------------------------------------+
		| caller's saved LR			| 4
		+---------------------------------------+
		| Parameter save area (P)		| 8
		+---------------------------------------+
		| Alloca space (A)			| 8+P
		+---------------------------------------+
		| Varargs save area (V)			| 8+P+A
		+---------------------------------------+
		| Local variable space (L)		| 8+P+A+V
		+---------------------------------------+
		| saved CR (C)				| 8+P+A+V+L
		+---------------------------------------+
		| Save area for GP registers (G)	| 8+P+A+V+L+C
		+---------------------------------------+
		| Save area for FP registers (F)	| 8+P+A+V+L+C+G
		+---------------------------------------+
	old SP->| back chain to caller's caller		|
		+---------------------------------------+
*/

rs6000_stack_t *
rs6000_stack_info ()
{
  static rs6000_stack_t info, zero_info;
  rs6000_stack_t *info_ptr = &info;
  int reg_size = TARGET_64BIT ? 8 : 4;
  enum rs6000_abi abi;

  /* Zero all fields portably */
  info = zero_info;

  /* Select which calling sequence */
#ifdef TARGET_V4_CALLS
  if (TARGET_V4_CALLS)
    abi = ABI_V4;
  else
#endif
    abi = ABI_AIX;

  info_ptr->abi = abi;

  /* Calculate which registers need to be saved & save area size */
  info_ptr->first_gp_reg_save = first_reg_to_save ();
  info_ptr->gp_size = reg_size * (32 - info_ptr->first_gp_reg_save);

  info_ptr->first_fp_reg_save = first_fp_reg_to_save ();
  info_ptr->fp_size = 8 * (64 - info_ptr->first_fp_reg_save);

  /* Does this function call anything? */
  info_ptr->calls_p = rs6000_makes_calls ();

  /* Determine if we need to save the link register */
  if (regs_ever_live[65] || profile_flag
#ifdef TARGET_RELOCATABLE
      || (TARGET_RELOCATABLE && (get_pool_size () != 0))
#endif
      || (info_ptr->first_fp_reg_save != 64
	  && !FP_SAVE_INLINE (info_ptr->first_fp_reg_save))
      || (abi == ABI_V4 && current_function_calls_alloca)
      || info_ptr->calls_p)
    {
      info_ptr->lr_save_p = 1;
      regs_ever_live[65] = 1;
    }

  /* Determine if we need to save the condition code registers */
  if (regs_ever_live[70] || regs_ever_live[71] || regs_ever_live[72])
    {
      info_ptr->cr_save_p = 1;
      if (abi == ABI_V4)
	info_ptr->cr_size = reg_size;
    }

  /* Determine various sizes */
  info_ptr->reg_size     = reg_size;
  info_ptr->fixed_size   = RS6000_SAVE_AREA;
  info_ptr->varargs_size = RS6000_VARARG