rs6000.c

gcc库的原代码,对编程有很大帮助.

/* Subroutines used for code generation on IBM RS/6000.
   Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
   Contributed by Richard Kenner ([e-mail])

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include <stdio.h>
#include <ctype.h>
#include "config.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "insn-flags.h"
#include "output.h"
#include "insn-attr.h"
#include "flags.h"
#include "recog.h"
#include "expr.h"
#include "obstack.h"
#include "tree.h"

extern char *language_string;
extern int profile_block_flag;

#define min(A,B)	((A) < (B) ? (A) : (B))
#define max(A,B)	((A) > (B) ? (A) : (B))

/* Target cpu type */

enum processor_type rs6000_cpu;
char *rs6000_cpu_string;

/* Set to non-zero by "fix" operation to indicate that itrunc and
   uitrunc must be defined.  */

int rs6000_trunc_used;

/* Set to non-zero once they have been defined.  */

static int trunc_defined;

/* Set to non-zero once AIX common-mode calls have been defined.  */
static int common_mode_defined;
/* Save information from a "cmpxx" operation until the branch or scc is
   emitted.  */

rtx rs6000_compare_op0, rs6000_compare_op1;
int rs6000_compare_fp_p;

#ifdef USING_SVR4_H
/* Label number of label created for -mrelocatable, to call to so we can
   get the address of the GOT section */
int rs6000_pic_labelno;
#endif

/* Whether a System V.4 varargs area was created.  */
int rs6000_sysv_varargs_p;

/* Temporary memory used to convert integer -> float */
static rtx stack_temps[NUM_MACHINE_MODES];


/* Print the options used in the assembly file.  */

extern char *version_string, *language_string;

struct asm_option
{
  char *string;
  int *variable;
  int on_value;
};

#define MAX_LINE 79

static int
output_option (file, type, name, pos)
     FILE *file;
     char *type;
     char *name;
     int pos;
{
  int type_len = strlen (type);
  int name_len = strlen (name);

  if (1 + type_len + name_len + pos > MAX_LINE)
    {
      fprintf (file, "\n # %s%s", type, name);
      return 3 + type_len + name_len;
    }
  fprintf (file, " %s%s", type, name);
  return pos + 1 + type_len + name_len;
}

static struct { char *name; int value; } m_options[] = TARGET_SWITCHES;

void
output_options (file, f_options, f_len, W_options, W_len)
     FILE *file;
     struct asm_option *f_options;
     int f_len;
     struct asm_option *W_options;
     int W_len;
{
  int j;
  int flags = target_flags;
  int pos = 32767;

  fprintf (file, " # %s %s", language_string, version_string);

  if (optimize)
    {
      char opt_string[20];
      sprintf (opt_string, "%d", optimize);
      pos = output_option (file, "-O", opt_string, pos);
    }

  if (profile_flag)
    pos = output_option (file, "-p", "", pos);

  if (profile_block_flag)
    pos = output_option (file, "-a", "", pos);

  if (inhibit_warnings)
    pos = output_option (file, "-w", "", pos);

  for (j = 0; j < f_len; j++)
    {
      if (*f_options[j].variable == f_options[j].on_value)
	pos = output_option (file, "-f", f_options[j].string, pos);
    }

  for (j = 0; j < W_len; j++)
    {
      if (*W_options[j].variable == W_options[j].on_value)
	pos = output_option (file, "-W", W_options[j].string, pos);
    }

  for (j = 0; j < sizeof m_options / sizeof m_options[0]; j++)
    {
      if (m_options[j].name[0] != '\0'
	  && m_options[j].value > 0
	  && ((m_options[j].value & flags) == m_options[j].value))
	{
	  pos = output_option (file, "-m", m_options[j].name, pos);
	  flags &= ~ m_options[j].value;
	}
    }

  if (rs6000_cpu_string != (char *)0)
    pos = output_option (file, "-mcpu=", rs6000_cpu_string, pos);

  fputs ("\n\n", file);
}


/* Override command line options.  Mostly we process the processor
   type and sometimes adjust other TARGET_ options.  */

void
rs6000_override_options ()
{
  int i;

  /* Simplify the entries below by making a mask for any POWER
     variant and any PowerPC variant.  */

#define POWER_MASKS (MASK_POWER | MASK_POWER2 | MASK_MULTIPLE | MASK_STRING)
#define POWERPC_MASKS (MASK_POWERPC | MASK_PPC_GPOPT \
		       | MASK_PPC_GFXOPT | MASK_POWERPC64)
#define POWERPC_OPT_MASKS (MASK_PPC_GPOPT | MASK_PPC_GFXOPT)

  static struct ptt
    {
      char *name;		/* Canonical processor name.  */
      enum processor_type processor; /* Processor type enum value.  */
      int target_enable;	/* Target flags to enable.  */
      int target_disable;	/* Target flags to disable.  */
    } processor_target_table[]
      = {{"common", PROCESSOR_COMMON, 0, POWER_MASKS | POWERPC_MASKS},
	 {"power", PROCESSOR_POWER,
	    MASK_POWER | MASK_MULTIPLE | MASK_STRING,
	    MASK_POWER2 | POWERPC_MASKS | MASK_NEW_MNEMONICS},
	 {"powerpc", PROCESSOR_POWERPC,
	    MASK_POWERPC | MASK_NEW_MNEMONICS,
	    POWER_MASKS | POWERPC_OPT_MASKS | MASK_POWERPC64},
	 {"rios", PROCESSOR_RIOS1,
	    MASK_POWER | MASK_MULTIPLE | MASK_STRING,
	    MASK_POWER2 | POWERPC_MASKS | MASK_NEW_MNEMONICS},
	 {"rios1", PROCESSOR_RIOS1,
	    MASK_POWER | MASK_MULTIPLE | MASK_STRING,
	    MASK_POWER2 | POWERPC_MASKS | MASK_NEW_MNEMONICS},
	 {"rsc", PROCESSOR_PPC601,
	    MASK_POWER | MASK_MULTIPLE | MASK_STRING,
	    MASK_POWER2 | POWERPC_MASKS | MASK_NEW_MNEMONICS},
	 {"rsc1", PROCESSOR_PPC601,
	    MASK_POWER | MASK_MULTIPLE | MASK_STRING,
	    MASK_POWER2 | POWERPC_MASKS | MASK_NEW_MNEMONICS},
	 {"rios2", PROCESSOR_RIOS2,
	    MASK_POWER | MASK_MULTIPLE | MASK_STRING | MASK_POWER2,
	    POWERPC_MASKS | MASK_NEW_MNEMONICS},
	 {"403", PROCESSOR_PPC403,
	    MASK_POWERPC | MASK_SOFT_FLOAT | MASK_NEW_MNEMONICS,
	    POWER_MASKS | POWERPC_OPT_MASKS | MASK_POWERPC64},
	 {"601", PROCESSOR_PPC601,
	    MASK_POWER | MASK_POWERPC | MASK_NEW_MNEMONICS | MASK_MULTIPLE | MASK_STRING,
	    MASK_POWER2 | POWERPC_OPT_MASKS | MASK_POWERPC64},
	 {"603", PROCESSOR_PPC603,
	    MASK_POWERPC | MASK_PPC_GFXOPT | MASK_NEW_MNEMONICS,
	    POWER_MASKS | MASK_PPC_GPOPT | MASK_POWERPC64},
	 {"604", PROCESSOR_PPC604,
	    MASK_POWERPC | MASK_PPC_GFXOPT | MASK_NEW_MNEMONICS,
	    POWER_MASKS | MASK_PPC_GPOPT | MASK_POWERPC64}};

  int ptt_size = sizeof (processor_target_table) / sizeof (struct ptt);

  int multiple = TARGET_MULTIPLE;	/* save current -mmultiple/-mno-multiple status */
  int string   = TARGET_STRING;		/* save current -mstring/-mno-string status */

  profile_block_flag = 0;

  /* Identify the processor type */
  if (rs6000_cpu_string == 0)
    rs6000_cpu = PROCESSOR_DEFAULT;
  else
    {
      for (i = 0; i < ptt_size; i++)
	if (! strcmp (rs6000_cpu_string, processor_target_table[i].name))
	  {
	    rs6000_cpu = processor_target_table[i].processor;
	    target_flags |= processor_target_table[i].target_enable;
	    target_flags &= ~processor_target_table[i].target_disable;
	    break;
	  }

      if (i == ptt_size)
	{
	  error ("bad value (%s) for -mcpu= switch", rs6000_cpu_string);
	  rs6000_cpu_string = "default";
	  rs6000_cpu = PROCESSOR_DEFAULT;
	}
    }

  /* If -mmultiple or -mno-multiple was explicitly used, don't
     override with the processor default */
  if (TARGET_MULTIPLE_SET)
    target_flags = (target_flags & ~MASK_MULTIPLE) | multiple;

  /* If -mstring or -mno-string was explicitly used, don't
     override with the processor default */
  if (TARGET_STRING_SET)
    target_flags = (target_flags & ~MASK_STRING) | string;

  /* Don't allow -mmultiple or -mstring on little endian systems, because the
     hardware doesn't support the instructions used in little endian mode */
  if (!BYTES_BIG_ENDIAN)
    {
      if (TARGET_MULTIPLE)
	{
	  target_flags &= ~MASK_MULTIPLE;
	  if (TARGET_MULTIPLE_SET)
	    warning ("-mmultiple is not supported on little endian systems");
	}

      if (TARGET_STRING)
	{
	  target_flags &= ~MASK_STRING;
	  if (TARGET_STRING_SET)
	    warning ("-mstring is not supported on little endian systems");
	}
    }

#ifdef SUBTARGET_OVERRIDE_OPTIONS
  SUBTARGET_OVERRIDE_OPTIONS;
#endif
}

/* Create a CONST_DOUBLE from a string.  */

struct rtx_def *
rs6000_float_const (string, mode)
     char *string;
     enum machine_mode mode;
{
  REAL_VALUE_TYPE value = REAL_VALUE_ATOF (string, mode);
  return immed_real_const_1 (value, mode);
}


/* Create a CONST_DOUBLE like immed_double_const, except reverse the
   two parts of the constant if the target is little endian.  */

struct rtx_def *
rs6000_immed_double_const (i0, i1, mode)
     HOST_WIDE_INT i0, i1;
     enum machine_mode mode;
{
  if (! WORDS_BIG_ENDIAN)
    return immed_double_const (i1, i0, mode);

  return immed_double_const (i0, i1, mode);
}


/* Return non-zero if this function is known to have a null epilogue.  */

int
direct_return ()
{
  if (reload_completed)
    {
      rs6000_stack_t *info = rs6000_stack_info ();

      if (info->first_gp_reg_save == 32
	  && info->first_fp_reg_save == 64
	  && !info->lr_save_p
	  && !info->cr_save_p
	  && !info->push_p)
	return 1;
    }

  return 0;
}

/* Returns 1 always.  */

int
any_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return 1;
}

/* Return 1 if OP is a constant that can fit in a D field.  */

int
short_cint_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_CODE (op) == CONST_INT
	  && (unsigned) (INTVAL (op) + 0x8000) < 0x10000);
}

/* Similar for a unsigned D field.  */

int
u_short_cint_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_CODE (op) == CONST_INT && (INTVAL (op) & 0xffff0000) == 0);
}

/* Return 1 if OP is a CONST_INT that cannot fit in a signed D field.  */

int
non_short_cint_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_CODE (op) == CONST_INT
	  && (unsigned) (INTVAL (op) + 0x8000) >= 0x10000);
}

/* Returns 1 if OP is a register that is not special (i.e., not MQ,
   ctr, or lr).  */

int
gpc_reg_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (register_operand (op, mode)
	  && (GET_CODE (op) != REG || REGNO (op) >= 67 || REGNO (op) < 64));
}

/* Returns 1 if OP is either a pseudo-register or a register denoting a
   CR field.  */

int
cc_reg_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (register_operand (op, mode)
	  && (GET_CODE (op) != REG
	      || REGNO (op) >= FIRST_PSEUDO_REGISTER
	      || CR_REGNO_P (REGNO (op))));
}

/* Returns 1 if OP is either a constant integer valid for a D-field or a
   non-special register.  If a register, it must be in the proper mode unless
   MODE is VOIDmode.  */

int
reg_or_short_operand (op, mode)
      register rtx op;
      enum machine_mode mode;
{
  return short_cint_operand (op, mode) || gpc_reg_operand (op, mode);
}

/* Similar, except check if the negation of the constant would be valid for
   a D-field.  */

int
reg_or_neg_short_operand (op, mode)
      register rtx op;
      enum machine_mode mode;
{
  if (GET_CODE (op) == CONST_INT)
    return CONST_OK_FOR_LETTER_P (INTVAL (op), 'P');

  return gpc_reg_operand (op, mode);
}

/* Return 1 if the operand is either a register or an integer whose high-order
   16 bits are zero.  */

int
reg_or_u_short_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  if (GET_CODE (op) == CONST_INT
      && (INTVAL (op) & 0xffff0000) == 0)
    return 1;

  return gpc_reg_operand (op, mode);
}

/* Return 1 is the operand is either a non-special register or ANY
   constant integer.  */

int
reg_or_cint_operand (op, mode)
    register rtx op;
    enum machine_mode mode;
{
     return GET_CODE (op) == CONST_INT || gpc_reg_operand (op, mode);
}

/* Return 1 if the operand is a CONST_DOUBLE and it can be put into a register
   with one instruction per word.  We only do this if we can safely read
   CONST_DOUBLE_{LOW,HIGH}.  */

int
easy_fp_constant (op, mode)
     register rtx op;
     register enum machine_mode mode;
{
  rtx low, high;

  if (GET_CODE (op) != CONST_DOUBLE
      || GET_MODE (op) != mode
      || GET_MODE_CLASS (mode) != MODE_FLOAT)
    return 0;

  high = operand_subword (op, 0, 0, mode);