ld/emultempl/mmo.em

   1 # This shell script emits a C file. -*- C -*-
   2 #   Copyright 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   3 #
   4 # This file is part of GLD, the Gnu Linker.
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 2 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program; if not, write to the Free Software
  18 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19 #
  20
  21 # This file is sourced from elf32.em and mmo.em, used to define
  22 # linker MMIX-specifics common to ELF and MMO.
  23
  24 cat >>e${EMULATION_NAME}.c <<EOF
  25 /* Need to have this define before mmix-elfnmmo, which includes
  26    needrelax.em which uses this name for the before_allocation function,
  27    normally defined in elf32.em.  */
  28 #define gldmmo_before_allocation before_allocation_default
  29 EOF
  30
  31 . ${srcdir}/emultempl/mmix-elfnmmo.em
  32
  33 cat >>e${EMULATION_NAME}.c <<EOF
  34
  35 /* Find the last output section before given output statement.
  36    Used by place_orphan.  */
  37
  38 static asection *
  39 output_prev_sec_find (lang_output_section_statement_type *os)
  40 {
  41   asection *s = NULL;
  42   lang_statement_union_type *u;
  43   lang_output_section_statement_type *lookup;
  44
  45   for (u = lang_output_section_statement.head;
  46        u != (lang_statement_union_type *) NULL;
  47        u = lookup->next)
  48     {
  49       lookup = &u->output_section_statement;
  50       if (lookup == os)
  51         break;
  52       if (lookup->bfd_section != NULL
  53           && lookup->bfd_section != bfd_abs_section_ptr
  54           && lookup->bfd_section != bfd_com_section_ptr
  55           && lookup->bfd_section != bfd_und_section_ptr)
  56         s = lookup->bfd_section;
  57     }
  58
  59   if (u == NULL)
  60     return NULL;
  61
  62   return s;
  63 }
  64
  65 struct orphan_save {
  66   lang_output_section_statement_type *os;
  67   asection **section;
  68   lang_statement_union_type **stmt;
  69 };
  70
  71 #define HAVE_SECTION(hold, name) \
  72 (hold.os != NULL || (hold.os = lang_output_section_find (name)) != NULL)
  73
  74 /* Place an orphan section.  We use this to put random SEC_CODE or
  75    SEC_READONLY sections right after MMO_TEXT_SECTION_NAME.  Much borrowed
  76    from elf32.em.  */
  77
  78 static bfd_boolean
  79 mmo_place_orphan (lang_input_statement_type *file, asection *s)
  80 {
  81   static struct orphan_save hold_text;
  82   struct orphan_save *place;
  83   lang_output_section_statement_type *os;
  84   lang_statement_list_type *old;
  85   lang_statement_list_type add;
  86   asection *snew, **pps, *bfd_section;
  87
  88   /* We have nothing to say for anything other than a final link.  */
  89   if (link_info.relocatable
  90       || (bfd_get_section_flags (s->owner, s)
  91           & (SEC_EXCLUDE | SEC_LOAD)) != SEC_LOAD)
  92     return FALSE;
  93
  94   /* Only care for sections we're going to load.  */
  95   os = lang_output_section_find (bfd_get_section_name (s->owner, s));
  96
  97   /* We have an output section by this name.  Place the section inside it
  98      (regardless of whether the linker script lists it as input).  */
  99   if (os != NULL)
 100     {
 101       lang_add_section (&os->children, s, os, file);
 102       return TRUE;
 103     }
 104
 105   /* If this section does not have .text-type section flags or there's no
 106      MMO_TEXT_SECTION_NAME, we don't have anything to say.  */
 107   if ((bfd_get_section_flags (s->owner, s) & (SEC_CODE | SEC_READONLY)) == 0)
 108     return FALSE;
 109
 110   if (hold_text.os == NULL)
 111     hold_text.os = lang_output_section_find (MMO_TEXT_SECTION_NAME);
 112
 113   place = &hold_text;
 114
 115   /* If there's an output section by this name, we'll use it, regardless
 116      of section flags, in contrast to what's done in elf32.em.  */
 117
 118   /* Start building a list of statements for this section.
 119      First save the current statement pointer.  */
 120   old = stat_ptr;
 121
 122   /* Add the output section statements for this orphan to our own private
 123      list, inserting them later into the global statement list.  */
 124   stat_ptr = &add;
 125   lang_list_init (stat_ptr);
 126
 127   os = lang_enter_output_section_statement (bfd_get_section_name (s->owner,
 128                                                                   s),
 129                                             NULL, 0,
 130                                             (etree_type *) NULL,
 131                                             (etree_type *) NULL,
 132                                             (etree_type *) NULL);
 133
 134   lang_add_section (&os->children, s, os, file);
 135
 136   lang_leave_output_section_statement
 137     ((bfd_vma) 0, "*default*",
 138      (struct lang_output_section_phdr_list *) NULL, NULL);
 139
 140   /* Restore the global list pointer.  */
 141   stat_ptr = old;
 142
 143   snew = os->bfd_section;
 144   if (snew == NULL)
 145     /* /DISCARD/ section.  */
 146     return TRUE;
 147
 148   /* We need an output section for .text as a root, so if there was none
 149      (might happen with a peculiar linker script such as in "map
 150      addresses", map-address.exp), we grab the output section created
 151      above.  */
 152   if (hold_text.os == NULL)
 153     {
 154       if (os == NULL)
 155         return FALSE;
 156       hold_text.os = os;
 157     }
 158
 159   bfd_section = place->os->bfd_section;
 160   if (place->section == NULL && bfd_section == NULL)
 161     bfd_section = output_prev_sec_find (place->os);
 162
 163   if (place->section != NULL
 164       || (bfd_section != NULL
 165           && bfd_section != snew))
 166     {
 167       /* Shuffle the section to make the output file look neater.  This is
 168          really only cosmetic.  */
 169       if (place->section == NULL)
 170         /* Put orphans after the first section on the list.  */
 171         place->section = &bfd_section->next;
 172
 173       /* Unlink the section.  */
 174       for (pps = &output_bfd->sections; *pps != snew; pps = &(*pps)->next)
 175         ;
 176       bfd_section_list_remove (output_bfd, pps);
 177
 178       /* Now tack it on to the "place->os" section list.  */
 179       bfd_section_list_insert (output_bfd, place->section, snew);
 180     }
 181   place->section = &snew->next; /* Save the end of this list.  */
 182
 183   if (add.head != NULL)
 184     {
 185       /* We try to put the output statements in some sort of reasonable
 186          order here, because they determine the final load addresses of
 187          the orphan sections.  */
 188       if (place->stmt == NULL)
 189         {
 190           /* Put the new statement list right at the head.  */
 191           *add.tail = place->os->header.next;
 192           place->os->header.next = add.head;
 193         }
 194       else
 195         {
 196           /* Put it after the last orphan statement we added.  */
 197           *add.tail = *place->stmt;
 198           *place->stmt = add.head;
 199         }
 200
 201       /* Fix the global list pointer if we happened to tack our new list
 202          at the tail.  */
 203       if (*old->tail == add.head)
 204         old->tail = add.tail;
 205
 206       /* Save the end of this list.  */
 207       place->stmt = add.tail;
 208     }
 209
 210   return TRUE;
 211 }
 212
 213 /* Remove the spurious settings of SEC_RELOC that make it to the output at
 214    link time.  We are as confused as elflink.h:elf_bfd_final_link, and
 215    paper over the bug similarly.  */
 216
 217 static void
 218 mmo_wipe_sec_reloc_flag (bfd *abfd, asection *sec, void *ptr ATTRIBUTE_UNUSED)
 219 {
 220   bfd_set_section_flags (abfd, sec,
 221                          bfd_get_section_flags (abfd, sec) & ~SEC_RELOC);
 222 }
 223
 224 /* Iterate with bfd_map_over_sections over mmo_wipe_sec_reloc_flag... */
 225
 226 static void
 227 mmo_finish (void)
 228 {
 229   bfd_map_over_sections (output_bfd, mmo_wipe_sec_reloc_flag, NULL);
 230 }
 231 \f
 232 /* To get on-demand global register allocation right, we need to parse the
 233    relocs, like what happens when linking to ELF.  It needs to be done
 234    before all input sections are supposed to be present.  When linking to
 235    ELF, it's done when reading symbols.  When linking to mmo, we do it
 236    when all input files are seen, which is equivalent.  */
 237
 238 static void
 239 mmo_after_open (void)
 240 {
 241   /* When there's a mismatch between the output format and the emulation
 242      (using weird combinations like "-m mmo --oformat elf64-mmix" for
 243      example), we'd count relocs twice because they'd also be counted
 244      along the usual route for ELF-only linking, which would lead to an
 245      internal accounting error.  */
 246   if (bfd_get_flavour (output_bfd) != bfd_target_elf_flavour)
 247     {
 248       LANG_FOR_EACH_INPUT_STATEMENT (is)
 249         {
 250           if (bfd_get_flavour (is->the_bfd) == bfd_target_elf_flavour
 251               && !_bfd_mmix_check_all_relocs (is->the_bfd, &link_info))
 252             einfo ("%X%P: Internal problems scanning %B after opening it",
 253                    is->the_bfd);
 254         }
 255     }
 256 }
 257 EOF
 258
 259 LDEMUL_PLACE_ORPHAN=mmo_place_orphan
 260 LDEMUL_FINISH=mmo_finish
 261 LDEMUL_AFTER_OPEN=mmo_after_open