Subversion Repositories openrisc_2011-10-31

/* tc-openrisc.c -- Assembler for the OpenRISC family.

   Copyright 2001, 2002, 2003, 2005, 2006, 2007 Free Software Foundation.

   Contributed by Johan Rydberg, jrydberg@opencores.org

   This file is part of GAS, the GNU Assembler.

   GAS 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 3, or (at your option)

   any later version.

   GAS 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 GAS; see the file COPYING.  If not, write to

   the Free Software Foundation, 51 Franklin Street - Fifth Floor,

   Boston, MA 02110-1301, USA.  */

#include "as.h"

#include "subsegs.h"

#include "symcat.h"

#include "opcodes/openrisc-desc.h"

#include "opcodes/openrisc-opc.h"

#include "cgen.h"

/* Structure to hold all of the different components describing

   an individual instruction.  */

typedef struct openrisc_insn openrisc_insn;

struct openrisc_insn

{

  const CGEN_INSN *     insn;

  const CGEN_INSN *     orig_insn;

  CGEN_FIELDS           fields;

#if CGEN_INT_INSN_P

  CGEN_INSN_INT         buffer [1];

#define INSN_VALUE(buf) (*(buf))

#else

  unsigned char         buffer [CGEN_MAX_INSN_SIZE];

#define INSN_VALUE(buf) (buf)

#endif

  char *                addr;

  fragS *               frag;

  int                   num_fixups;

  fixS *                fixups [GAS_CGEN_MAX_FIXUPS];

  int                   indices [MAX_OPERAND_INSTANCES];

};

const char comment_chars[]        = "#";

const char line_comment_chars[]   = "#";

const char line_separator_chars[] = ";";

const char EXP_CHARS[]            = "eE";

const char FLT_CHARS[]            = "dD";

#define OPENRISC_SHORTOPTS "m:"

const char * md_shortopts = OPENRISC_SHORTOPTS;

struct option md_longopts[] =

{

  {NULL, no_argument, NULL, 0}

};

size_t md_longopts_size = sizeof (md_longopts);

unsigned long openrisc_machine = 0; /* default */

int

md_parse_option (int c ATTRIBUTE_UNUSED, char * arg ATTRIBUTE_UNUSED)

{

  return 0;

}

void

md_show_usage (FILE * stream ATTRIBUTE_UNUSED)

{

}

static void

ignore_pseudo (int val ATTRIBUTE_UNUSED)

{

  discard_rest_of_line ();

}

const char openrisc_comment_chars [] = ";#";

/* The target specific pseudo-ops which we support.  */

const pseudo_typeS md_pseudo_table[] =

{

  { "word",     cons,           4 },

  { "proc",     ignore_pseudo,  0 },

  { "endproc",  ignore_pseudo,  0 },

  { NULL,       NULL,           0 }

};

void

md_begin (void)

{

  /* Initialize the `cgen' interface.  */

  /* Set the machine number and endian.  */

  gas_cgen_cpu_desc = openrisc_cgen_cpu_open (CGEN_CPU_OPEN_MACHS, 0,

                                              CGEN_CPU_OPEN_ENDIAN,

                                              CGEN_ENDIAN_BIG,

                                              CGEN_CPU_OPEN_END);

  openrisc_cgen_init_asm (gas_cgen_cpu_desc);

  /* This is a callback from cgen to gas to parse operands.  */

  cgen_set_parse_operand_fn (gas_cgen_cpu_desc, gas_cgen_parse_operand);

}

void

md_assemble (char * str)

{

  static int last_insn_had_delay_slot = 0;

  openrisc_insn insn;

  char *    errmsg;

  /* Initialize GAS's cgen interface for a new instruction.  */

  gas_cgen_init_parse ();

  insn.insn = openrisc_cgen_assemble_insn

    (gas_cgen_cpu_desc, str, & insn.fields, insn.buffer, & errmsg);

  if (!insn.insn)

    {

      as_bad (errmsg);

      return;

    }

  /* Doesn't really matter what we pass for RELAX_P here.  */

  gas_cgen_finish_insn (insn.insn, insn.buffer,

                        CGEN_FIELDS_BITSIZE (& insn.fields), 1, NULL);

  last_insn_had_delay_slot

    = CGEN_INSN_ATTR_VALUE (insn.insn, CGEN_INSN_DELAY_SLOT);

}

/* The syntax in the manual says constants begin with '#'.

   We just ignore it.  */

void

md_operand (expressionS * expressionP)

{

  if (* input_line_pointer == '#')

    {

      input_line_pointer ++;

      expression (expressionP);

    }

}

valueT

md_section_align (segT segment, valueT size)

{

  int align = bfd_get_section_alignment (stdoutput, segment);

  return ((size + (1 << align) - 1) & (-1 << align));

}

symbolS *

md_undefined_symbol (char * name ATTRIBUTE_UNUSED)

{

  return 0;

}

/* Interface to relax_segment.  */

/* FIXME: Look through this.  */

const relax_typeS md_relax_table[] =

{

/* The fields are:

   1) most positive reach of this state,

   2) most negative reach of this state,

   3) how many bytes this mode will add to the size of the current frag

   4) which index into the table to try if we can't fit into this one.  */

  /* The first entry must be unused because an `rlx_more' value of zero ends

     each list.  */

  {1, 1, 0, 0},

  /* The displacement used by GAS is from the end of the 2 byte insn,

     so we subtract 2 from the following.  */

  /* 16 bit insn, 8 bit disp -> 10 bit range.

     This doesn't handle a branch in the right slot at the border:

     the "& -4" isn't taken into account.  It's not important enough to

     complicate things over it, so we subtract an extra 2 (or + 2 in -ve

     case).  */

  {511 - 2 - 2, -512 - 2 + 2, 0, 2 },

  /* 32 bit insn, 24 bit disp -> 26 bit range.  */

  {0x2000000 - 1 - 2, -0x2000000 - 2, 2, 0 },

  /* Same thing, but with leading nop for alignment.  */

  {0x2000000 - 1 - 2, -0x2000000 - 2, 4, 0 }

};

/* Return an initial guess of the length by which a fragment must grow to

   hold a branch to reach its destination.

   Also updates fr_type/fr_subtype as necessary.

   Called just before doing relaxation.

   Any symbol that is now undefined will not become defined.

   The guess for fr_var is ACTUALLY the growth beyond fr_fix.

   Whatever we do to grow fr_fix or fr_var contributes to our returned value.

   Although it may not be explicit in the frag, pretend fr_var starts with a

int

md_estimate_size_before_relax (fragS * fragP, segT segment)

{

  /* The only thing we have to handle here are symbols outside of the

     current segment.  They may be undefined or in a different segment in

     which case linker scripts may place them anywhere.

     However, we can't finish the fragment here and emit the reloc as insn

     alignment requirements may move the insn about.  */

  if (S_GET_SEGMENT (fragP->fr_symbol) != segment)

    {

      /* The symbol is undefined in this segment.

         Change the relaxation subtype to the max allowable and leave

         all further handling to md_convert_frag.  */

      fragP->fr_subtype = 2;

      {

        const CGEN_INSN * insn;

        int               i;

        /* Update the recorded insn.

           Fortunately we don't have to look very far.

           FIXME: Change this to record in the instruction the next higher

           relaxable insn to use.  */

        for (i = 0, insn = fragP->fr_cgen.insn; i < 4; i++, insn++)

          {

            if ((strcmp (CGEN_INSN_MNEMONIC (insn),

                         CGEN_INSN_MNEMONIC (fragP->fr_cgen.insn))

                 == 0)

                && CGEN_INSN_ATTR_VALUE (insn, CGEN_INSN_RELAXED))

              break;

          }

        if (i == 4)

          abort ();

        fragP->fr_cgen.insn = insn;

        return 2;

      }

    }

  return md_relax_table[fragP->fr_subtype].rlx_length;

}

/* *fragP has been relaxed to its final size, and now needs to have

   the bytes inside it modified to conform to the new size.

   Called after relaxation is finished.

   fragP->fr_type == rs_machine_dependent.

   fragP->fr_subtype is the subtype of what the address relaxed to.  */

void

md_convert_frag (bfd *   abfd ATTRIBUTE_UNUSED,

                 segT    sec  ATTRIBUTE_UNUSED,

                 fragS * fragP ATTRIBUTE_UNUSED)

{

  /* FIXME */

}

/* Functions concerning relocs.  */

/* The location from which a PC relative jump should be calculated,

   given a PC relative reloc.  */

long

md_pcrel_from_section (fixS * fixP, segT sec)

{

  if (fixP->fx_addsy != (symbolS *) NULL

      && (! S_IS_DEFINED (fixP->fx_addsy)

          || S_GET_SEGMENT (fixP->fx_addsy) != sec))

    /* The symbol is undefined (or is defined but not in this section).

       Let the linker figure it out.  */

    return 0;

  return (fixP->fx_frag->fr_address + fixP->fx_where) & ~1;

}

/* Return the bfd reloc type for OPERAND of INSN at fixup FIXP.

   Returns BFD_RELOC_NONE if no reloc type can be found.

   *FIXP may be modified if desired.  */

bfd_reloc_code_real_type

md_cgen_lookup_reloc (const CGEN_INSN *    insn ATTRIBUTE_UNUSED,

                      const CGEN_OPERAND * operand,

                      fixS *               fixP)

{

  bfd_reloc_code_real_type type;

  switch (operand->type)

    {

    case OPENRISC_OPERAND_ABS_26:

      fixP->fx_pcrel = 0;

      type = BFD_RELOC_OPENRISC_ABS_26;

      goto emit;

    case OPENRISC_OPERAND_DISP_26:

      fixP->fx_pcrel = 1;

      type = BFD_RELOC_OPENRISC_REL_26;

      goto emit;

    case OPENRISC_OPERAND_HI16:

      type = BFD_RELOC_HI16;

      goto emit;

    case OPENRISC_OPERAND_LO16:

      type = BFD_RELOC_LO16;

      goto emit;

    emit:

      return type;

    default : /* avoid -Wall warning */

      break;

    }

  return BFD_RELOC_NONE;

}

/* Write a value out to the object file, using the appropriate endianness.  */

void

md_number_to_chars (char * buf, valueT val, int n)

{

  number_to_chars_bigendian (buf, val, n);

}

/* Turn a string in input_line_pointer into a floating point constant of type

   type, and store the appropriate bytes in *litP.  The number of LITTLENUMS

   emitted is stored in *sizeP .  An error message is returned, or NULL on OK.

*/

/* Equal to MAX_PRECISION in atof-ieee.c */

#define MAX_LITTLENUMS 6

char *

md_atof (int type, char * litP, int *  sizeP)

{

  return ieee_md_atof (type, litP, sizeP, TRUE);

}

bfd_boolean

openrisc_fix_adjustable (fixS * fixP)

{

  /* We need the symbol name for the VTABLE entries.  */

  if (fixP->fx_r_type == BFD_RELOC_VTABLE_INHERIT

      || fixP->fx_r_type == BFD_RELOC_VTABLE_ENTRY)

    return 0;

  return 1;

}