/* subsegs.c - subsegments -

   Copyright (C) 1987-2025 Free Software Foundation, Inc.

   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.  */

/* Segments & sub-segments.  */

#include "as.h"

#include "subsegs.h"

#include "obstack.h"

frchainS *frchain_now;

static struct obstack frchains;

static fragS dummy_frag;

void

subsegs_begin (void)

{

  obstack_begin (&frchains, chunksize);

#if __GNUC__ >= 2

  obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1;

#endif

  frchain_now = NULL;   /* Warn new_subseg() that we are booting.  */

  frag_now = &dummy_frag;

}

void

subsegs_end (struct obstack **obs)

{

  for (; *obs; obs++)

    _obstack_free (*obs, NULL);

  _obstack_free (&frchains, NULL);

  bfd_set_section_userdata (bfd_com_section_ptr, NULL);

  bfd_set_section_userdata (bfd_und_section_ptr, NULL);

  bfd_set_section_userdata (bfd_abs_section_ptr, NULL);

  bfd_set_section_userdata (bfd_ind_section_ptr, NULL);

  /* Reverse bfd_std_section_init, so the sections look as they did

     initially.  This, and clearing out userdata above, is so we don't

     leave dangling pointers into freed memory for oss-fuzz to mess

     with.  */

  asymbol *global_syms = bfd_com_section_ptr->symbol;

  bfd_und_section_ptr->used_by_bfd = NULL;

  bfd_und_section_ptr->symbol = global_syms + (bfd_und_section_ptr

                 - bfd_com_section_ptr);

  bfd_abs_section_ptr->used_by_bfd = NULL;

  bfd_abs_section_ptr->symbol = global_syms + (bfd_abs_section_ptr

                 - bfd_com_section_ptr);

}

static void

alloc_seginfo (segT seg)

{

  segment_info_type *seginfo;

  seginfo = obstack_alloc (&notes, sizeof (*seginfo));

  memset (seginfo, 0, sizeof (*seginfo));

  bfd_set_section_userdata (seg, seginfo);

}

/*

 *      subseg_change()

 *

 * Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the

 * subsegment. If we are already in the correct subsegment, change nothing.

 * This is used eg as a worker for subseg_set [which does make a new frag_now]

 * and for changing segments after we have read the source. We construct eg

 * fixSs even after the source file is read, so we do have to keep the

 * segment context correct.

 */

void

subseg_change (segT seg, int subseg)

{

  now_seg = seg;

  now_subseg = subseg;

  if (!seg_info (seg))

    alloc_seginfo (seg);

}

static void

subseg_set_rest (segT seg, subsegT subseg)

{

  frchainS *frcP;   /* crawl frchain chain */

  frchainS **lastPP;    /* address of last pointer */

  frchainS *newP;   /* address of new frchain */

  segment_info_type *seginfo;

  mri_common_symbol = NULL;

  if (frag_now && frchain_now)

    frchain_now->frch_frag_now = frag_now;

  gas_assert (frchain_now == 0

    || frchain_now->frch_last == frag_now);

  subseg_change (seg, (int) subseg);

  seginfo = seg_info (seg);

  /* Should the section symbol be kept?  */

  if (bfd_keep_unused_section_symbols (stdoutput))

    seg->symbol->flags |= BSF_SECTION_SYM_USED;

  /* Attempt to find or make a frchain for that subsection.

     We keep the list sorted by subsection number.  */

  for (frcP = *(lastPP = &seginfo->frchainP);

       frcP != NULL;

       frcP = *(lastPP = &frcP->frch_next))

    if (frcP->frch_subseg >= subseg)

      break;

  if (frcP == NULL || frcP->frch_subseg != subseg)

    {

      /* This should be the only code that creates a frchainS.  */

      newP = (frchainS *) obstack_alloc (&frchains, sizeof (frchainS));

      newP->frch_subseg = subseg;

      newP->fix_root = NULL;

      newP->fix_tail = NULL;

      obstack_begin (&newP->frch_obstack, chunksize);

#if __GNUC__ >= 2

      obstack_alignment_mask (&newP->frch_obstack) = __alignof__ (fragS) - 1;

#endif

      newP->frch_frag_now = frag_alloc (&newP->frch_obstack, 0);

      newP->frch_frag_now->fr_type = rs_fill;

      newP->frch_cfi_data = NULL;

      newP->frch_ginsn_data = NULL;

      newP->frch_root = newP->frch_last = newP->frch_frag_now;

      *lastPP = newP;

      newP->frch_next = frcP;

      frcP = newP;

    }

  frchain_now = frcP;

  frag_now = frcP->frch_frag_now;

  gas_assert (frchain_now->frch_last == frag_now);

}

/*

 *      subseg_set(segT, subsegT)

 *

 * If you attempt to change to the current subsegment, nothing happens.

 *

 * In:  segT, subsegT code for new subsegment.

 *  frag_now -> incomplete frag for current subsegment.

 *  If frag_now==NULL, then there is no old, incomplete frag, so

 *  the old frag is not closed off.

 *

 * Out: now_subseg, now_seg updated.

 *  Frchain_now points to the (possibly new) struct frchain for this

 *  sub-segment.

 */

segT

subseg_get (const char *segname, int force_new)

{

  segT secptr;

  const char *now_seg_name = now_seg ? bfd_section_name (now_seg) : 0;

  if (!force_new

      && now_seg_name

      && (now_seg_name == segname

    || !strcmp (now_seg_name, segname)))

    return now_seg;

  if (!force_new)

    secptr = bfd_make_section_old_way (stdoutput, segname);

  else

    secptr = bfd_make_section_anyway (stdoutput, segname);

  if (!seg_info (secptr))

    {

      secptr->output_section = secptr;

      alloc_seginfo (secptr);

    }

  return secptr;

}

segT

subseg_new (const char *segname, subsegT subseg)

{

  segT secptr;

  secptr = subseg_get (segname, 0);

  subseg_set_rest (secptr, subseg);

  return secptr;

}

/* Like subseg_new, except a new section is always created, even if

   a section with that name already exists.  */

segT

subseg_force_new (const char *segname, subsegT subseg)

{

  segT secptr;

  secptr = subseg_get (segname, 1);

  subseg_set_rest (secptr, subseg);

  return secptr;

}

void

subseg_set (segT secptr, subsegT subseg)

{

  if (! (secptr == now_seg && subseg == now_subseg))

    subseg_set_rest (secptr, subseg);

  mri_common_symbol = NULL;

}

#ifndef obj_sec_sym_ok_for_reloc

#define obj_sec_sym_ok_for_reloc(SEC) 0

#endif

symbolS *

section_symbol (segT sec)

{

  segment_info_type *seginfo = seg_info (sec);

  symbolS *s;

  if (seginfo == 0)

    abort ();

  if (seginfo->sym)

    return seginfo->sym;

#ifndef EMIT_SECTION_SYMBOLS

#define EMIT_SECTION_SYMBOLS 1

#endif

  if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen)

    {

      /* Here we know it won't be going into the symbol table.  */

      s = symbol_create (sec->symbol->name, sec, &zero_address_frag, 0);

    }

  else

    {

      segT seg;

      s = symbol_find (sec->symbol->name);

      /* We have to make sure it is the right symbol when we

   have multiple sections with the same section name.  */

      if (s == NULL

    || ((seg = S_GET_SEGMENT (s)) != sec

        && seg != undefined_section))

  s = symbol_new (sec->symbol->name, sec, &zero_address_frag, 0);

      else if (seg == undefined_section)

  {

    S_SET_SEGMENT (s, sec);

    symbol_set_frag (s, &zero_address_frag);

  }

    }

  S_CLEAR_EXTERNAL (s);

  /* Use the BFD section symbol, if possible.  */

  if (obj_sec_sym_ok_for_reloc (sec))

    symbol_set_bfdsym (s, sec->symbol);

  else

    symbol_get_bfdsym (s)->flags |= BSF_SECTION_SYM;

  seginfo->sym = s;

  return s;

}

/* Return whether the specified segment is thought to hold text.  */

int

subseg_text_p (segT sec)

{

  return (bfd_section_flags (sec) & SEC_CODE) != 0;

}

/* Return non zero if SEC has at least one byte of data.  It is

   possible that we'll return zero even on a non-empty section because

   we don't know all the fragment types, and it is possible that an

   fr_fix == 0 one still contributes data.  Think of this as

   seg_definitely_not_empty_p.  */

int

seg_not_empty_p (segT sec ATTRIBUTE_UNUSED)

{

  segment_info_type *seginfo = seg_info (sec);

  frchainS *chain;

  fragS *frag;

  if (!seginfo)

    return 0;

  for (chain = seginfo->frchainP; chain; chain = chain->frch_next)

    {

      for (frag = chain->frch_root; frag; frag = frag->fr_next)

  if (frag->fr_fix)

    return 1;

      if (obstack_next_free (&chain->frch_obstack)

    != chain->frch_last->fr_literal)

  return 1;

    }

  return 0;

}

void

subsegs_print_statistics (FILE *file)

{

  frchainS *frchp;

  asection *s;

  /* PR 20897 - check to see if the output bfd was actually created.  */

  if (stdoutput == NULL)

    return;

  fprintf (file, "frag chains:\n");

  for (s = stdoutput->sections; s; s = s->next)

    {

      segment_info_type *seginfo;

      /* Skip gas-internal sections.  */

      if (segment_name (s)[0] == '*')

  continue;

      seginfo = seg_info (s);

      if (!seginfo)

  continue;

      for (frchp = seginfo->frchainP; frchp; frchp = frchp->frch_next)

  {

    int count = 0;

    fragS *fragp;

    for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next)

      count++;

    fprintf (file, "\n");

    fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp,

       segment_name (s), count);

  }

    }

}

/* end of subsegs.c */