gas/subsegs.h

   1 /* subsegs.h -> subsegs.c
   2    Copyright (C) 1987, 92, 93, 94, 95, 96, 1998 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS 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, or (at your option)
   9    any later version.
  10
  11    GAS 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 GAS; see the file COPYING.  If not, write to the Free
  18    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19    02111-1307, 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 #include "obstack.h"
  41
  42 struct frchain                  /* control building of a frag chain */
  43 {                               /* FRCH = FRagment CHain control */
  44   struct frag *frch_root;       /* 1st struct frag in chain, or NULL */
  45   struct frag *frch_last;       /* last struct frag in chain, or NULL */
  46   struct frchain *frch_next;    /* next in chain of struct frchain-s */
  47   segT frch_seg;                /* SEG_TEXT or SEG_DATA. */
  48   subsegT frch_subseg;          /* subsegment number of this chain */
  49 #ifdef BFD_ASSEMBLER
  50   fixS *fix_root;               /* Root of fixups for this subsegment.  */
  51   fixS *fix_tail;               /* Last fixup for this subsegment.  */
  52 #endif
  53   struct obstack frch_obstack;  /* for objects in this frag chain */
  54   fragS *frch_frag_now;         /* frag_now for this subsegment */
  55 };
  56
  57 typedef struct frchain frchainS;
  58
  59 /* All subsegments' chains hang off here.  NULL means no frchains yet.  */
  60 extern frchainS *frchain_root;
  61
  62 /* Frchain we are assembling into now.  That is, the current segment's
  63    frag chain, even if it contains no (complete) frags. */
  64 extern frchainS *frchain_now;
  65
  66
  67 typedef struct segment_info_struct
  68 {
  69   frchainS *frchainP;
  70   unsigned int hadone : 1;
  71
  72   /* This field is set if this is a .bss section which does not really
  73      have any contents.  Once upon a time a .bss section did not have
  74      any frags, but that is no longer true.  This field prevent the
  75      SEC_HAS_CONTENTS flag from being set for the section even if
  76      there are frags.  */
  77   unsigned int bss : 1;
  78
  79   int user_stuff;
  80
  81   /* Fixups for this segment.  If BFD_ASSEMBLER, this is only valid
  82      after the frchains are run together.  */
  83   fixS *fix_root;
  84   fixS *fix_tail;
  85
  86 #if defined (MANY_SEGMENTS) && !defined (BFD_ASSEMBLER)
  87   struct internal_scnhdr scnhdr;
  88   enum linkonce_type linkonce;
  89   const char *name;
  90 #endif
  91
  92   symbolS *dot;
  93
  94   struct lineno_list *lineno_list_head;
  95   struct lineno_list *lineno_list_tail;
  96
  97 #ifdef BFD_ASSEMBLER
  98   /* Which BFD section does this gas segment correspond to?  */
  99   asection *bfd_section;
 100
 101   /* NULL, or pointer to the gas symbol that is the section symbol for
 102      this section.  sym->bsym and bfd_section->symbol should be the same.  */
 103   symbolS *sym;
 104 #endif
 105
 106   union
 107     {
 108       /* Current size of section holding stabs strings.  */
 109       unsigned long stab_string_size;
 110       /* Initial frag for ELF.  */
 111       char *p;
 112     }
 113   stabu;
 114
 115 #ifdef NEED_LITERAL_POOL
 116   unsigned long literal_pool_size;
 117 #endif
 118
 119 #ifdef TC_SEGMENT_INFO_TYPE
 120   TC_SEGMENT_INFO_TYPE tc_segment_info_data;
 121 #endif
 122 } segment_info_type;
 123
 124 #ifdef BFD_ASSEMBLER
 125
 126 extern segment_info_type *seg_info PARAMS ((segT));
 127 extern symbolS *section_symbol PARAMS ((segT));
 128
 129 #else /* ! BFD_ASSEMBLER */
 130
 131 #ifdef MANY_SEGMENTS
 132
 133 extern segment_info_type segment_info[];
 134
 135 #define seg_info(SEC)   (&segment_info[SEC])
 136
 137 #else
 138
 139 /* Sentinel for frchain crawling.  Points to the 1st data-segment
 140    frchain.  (Which is pointed to by the last text-segment frchain.) */
 141 extern frchainS *data0_frchainP;
 142 extern frchainS *bss0_frchainP;
 143
 144 /* Dummy so stuff can compile.  Should never be used.  */
 145 struct seg_info_trash {
 146   struct {
 147     unsigned stab_string_size : 1;
 148   } stabu;
 149   unsigned hadone : 1;
 150 };
 151 #define seg_info(S)     (abort (), (struct seg_info_trash *) 0)
 152
 153 #endif
 154
 155 #endif /* ! BFD_ASSEMBLER */
 156
 157 extern void subsegs_print_statistics PARAMS ((FILE *));
 158
 159 /* end of subsegs.h */