gas/subsegs.h

   1 /* subsegs.h -> subsegs.c
   2
   3    Copyright (C) 1987, 1992, 1993, 1994 Free Software Foundation, Inc.
   4
   5    This file is part of GAS, the GNU Assembler.
   6
   7    GAS is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GAS; see the file COPYING.  If not, write to
  19    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 /*
  22  * For every sub-segment the user mentions in the ASsembler program,
  23  * we make one struct frchain. Each sub-segment has exactly one struct frchain
  24  * and vice versa.
  25  *
  26  * Struct frchain's are forward chained (in ascending order of sub-segment
  27  * code number). The chain runs through frch_next of each subsegment.
  28  * This makes it hard to find a subsegment's frags
  29  * if programmer uses a lot of them. Most programs only use text0 and
  30  * data0, so they don't suffer. At least this way:
  31  * (1)  There are no "arbitrary" restrictions on how many subsegments
  32  *      can be programmed;
  33  * (2)  Subsegments' frchain-s are (later) chained together in the order in
  34  *      which they are emitted for object file viz text then data.
  35  *
  36  * From each struct frchain dangles a chain of struct frags. The frags
  37  * represent code fragments, for that sub-segment, forward chained.
  38  */
  39
  40 struct frchain                  /* control building of a frag chain */
  41 {                               /* FRCH = FRagment CHain control */
  42   struct frag *frch_root;       /* 1st struct frag in chain, or NULL */
  43   struct frag *frch_last;       /* last struct frag in chain, or NULL */
  44   struct frchain *frch_next;    /* next in chain of struct frchain-s */
  45   segT frch_seg;                /* SEG_TEXT or SEG_DATA. */
  46   subsegT frch_subseg;          /* subsegment number of this chain */
  47 #ifdef BFD_ASSEMBLER
  48   fixS *fix_root;               /* Root of fixups for this subsegment.  */
  49   fixS *fix_tail;               /* Last fixup for this subsegment.  */
  50 #endif
  51   struct obstack frch_obstack;  /* for objects in this frag chain */
  52 };
  53
  54 typedef struct frchain frchainS;
  55
  56 /* All subsegments' chains hang off here.  NULL means no frchains yet.  */
  57 extern frchainS *frchain_root;
  58
  59 /* Frchain we are assembling into now That is, the current segment's
  60    frag chain, even if it contains no (complete) frags. */
  61 extern frchainS *frchain_now;
  62
  63
  64 typedef struct
  65 {
  66   frchainS *frchainP;
  67   int hadone : 1;
  68
  69   /* This field is set if this is a .bss section which does not really
  70      have any contents.  Once upon a time a .bss section did not have
  71      any frags, but that is no longer true.  This field prevent the
  72      SEC_HAS_CONTENTS flag from being set for the section even if
  73      there are frags.  */
  74   int bss : 1;
  75
  76   int user_stuff;
  77
  78   /* Fixups for this segment.  If BFD_ASSEMBLER, this is only valid
  79      after the frchains are run together.  */
  80   fixS *fix_root;
  81   fixS *fix_tail;
  82
  83 #if defined (MANY_SEGMENTS) && !defined (BFD_ASSEMBLER)
  84   struct internal_scnhdr scnhdr;
  85 #endif
  86   symbolS *dot;
  87
  88   struct lineno_list *lineno_list_head;
  89   struct lineno_list *lineno_list_tail;
  90
  91 #ifdef BFD_ASSEMBLER
  92   /* Which BFD section does this gas segment correspond to?  */
  93   asection *bfd_section;
  94
  95   /* NULL, or pointer to the gas symbol that is the section symbol for
  96      this section.  sym->bsym and bfd_section->symbol should be the same.  */
  97   symbolS *sym;
  98 #endif
  99
 100   union
 101     {
 102       /* Current size of section holding stabs strings.  */
 103       unsigned long stab_string_size;
 104       /* Initial frag for ELF.  */
 105       char *p;
 106     }
 107   stabu;
 108
 109 #ifdef NEED_LITERAL_POOL
 110   unsigned long literal_pool_size;
 111 #endif
 112 } segment_info_type;
 113
 114 #ifdef BFD_ASSEMBLER
 115
 116 extern segment_info_type *seg_info PARAMS ((segT));
 117 extern symbolS *section_symbol PARAMS ((segT));
 118
 119 #else /* ! BFD_ASSEMBLER */
 120
 121 #ifdef MANY_SEGMENTS
 122
 123 extern segment_info_type segment_info[];
 124
 125 #define seg_info(SEC)   (&segment_info[SEC])
 126
 127 #else
 128
 129 /* Sentinel for frchain crawling.  Points to the 1st data-segment
 130    frchain.  (Which is pointed to by the last text-segment frchain.) */
 131 extern frchainS *data0_frchainP;
 132 extern frchainS *bss0_frchainP;
 133
 134 #endif
 135
 136 #endif /* ! BFD_ASSEMBLER */
 137
 138 /* end of subsegs.h */