gas/subsegs.h

   1 /* subsegs.h -> subsegs.c
   2    Copyright 1987, 1992, 1993, 1994, 1995, 1996, 1998, 2000, 2003, 2005
   3    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 the Free
  19    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  20    02110-1301, USA.  */
  21
  22 /*
  23  * For every sub-segment the user mentions in the ASsembler program,
  24  * we make one struct frchain. Each sub-segment has exactly one struct frchain
  25  * and vice versa.
  26  *
  27  * Struct frchain's are forward chained (in ascending order of sub-segment
  28  * code number). The chain runs through frch_next of each subsegment.
  29  * This makes it hard to find a subsegment's frags
  30  * if programmer uses a lot of them. Most programs only use text0 and
  31  * data0, so they don't suffer. At least this way:
  32  * (1)  There are no "arbitrary" restrictions on how many subsegments
  33  *      can be programmed;
  34  * (2)  Subsegments' frchain-s are (later) chained together in the order in
  35  *      which they are emitted for object file viz text then data.
  36  *
  37  * From each struct frchain dangles a chain of struct frags. The frags
  38  * represent code fragments, for that sub-segment, forward chained.
  39  */
  40
  41 #include "obstack.h"
  42
  43 struct frchain                  /* control building of a frag chain */
  44 {                               /* FRCH = FRagment CHain control */
  45   struct frag *frch_root;       /* 1st struct frag in chain, or NULL */
  46   struct frag *frch_last;       /* last struct frag in chain, or NULL */
  47   struct frchain *frch_next;    /* next in chain of struct frchain-s */
  48   segT frch_seg;                /* SEG_TEXT or SEG_DATA.  */
  49   subsegT frch_subseg;          /* subsegment number of this chain */
  50 #ifdef BFD_ASSEMBLER
  51   fixS *fix_root;               /* Root of fixups for this subsegment.  */
  52   fixS *fix_tail;               /* Last fixup for this subsegment.  */
  53 #endif
  54   struct obstack frch_obstack;  /* for objects in this frag chain */
  55   fragS *frch_frag_now;         /* frag_now for this subsegment */
  56 };
  57
  58 typedef struct frchain frchainS;
  59
  60 /* All subsegments' chains hang off here.  NULL means no frchains yet.  */
  61 extern frchainS *frchain_root;
  62
  63 /* Frchain we are assembling into now.  That is, the current segment's
  64    frag chain, even if it contains no (complete) frags.  */
  65 extern frchainS *frchain_now;
  66
  67 typedef struct segment_info_struct {
  68   frchainS *frchainP;
  69   unsigned int hadone : 1;
  70
  71   /* This field is set if this is a .bss section which does not really
  72      have any contents.  Once upon a time a .bss section did not have
  73      any frags, but that is no longer true.  This field prevent the
  74      SEC_HAS_CONTENTS flag from being set for the section even if
  75      there are frags.  */
  76   unsigned int bss : 1;
  77
  78   int user_stuff;
  79
  80   /* Fixups for this segment.  If BFD_ASSEMBLER, this is only valid
  81      after the frchains are run together.  */
  82   fixS *fix_root;
  83   fixS *fix_tail;
  84
  85 #if defined (MANY_SEGMENTS) && !defined (BFD_ASSEMBLER)
  86   struct internal_scnhdr scnhdr;
  87   enum linkonce_type linkonce;
  88   const char *name;
  89 #endif
  90
  91   symbolS *dot;
  92
  93   struct lineno_list *lineno_list_head;
  94   struct lineno_list *lineno_list_tail;
  95
  96 #ifdef BFD_ASSEMBLER
  97   /* Which BFD section does this gas segment correspond to?  */
  98   asection *bfd_section;
  99
 100   /* NULL, or pointer to the gas symbol that is the section symbol for
 101      this section.  sym->bsym and bfd_section->symbol should be the same.  */
 102   symbolS *sym;
 103 #endif
 104
 105   union {
 106     /* Current size of section holding stabs strings.  */
 107     unsigned long stab_string_size;
 108     /* Initial frag for ELF.  */
 109     char *p;
 110   }
 111   stabu;
 112
 113 #ifdef NEED_LITERAL_POOL
 114   unsigned long literal_pool_size;
 115 #endif
 116
 117 #ifdef TC_SEGMENT_INFO_TYPE
 118   TC_SEGMENT_INFO_TYPE tc_segment_info_data;
 119 #endif
 120 } segment_info_type;
 121
 122 #ifdef BFD_ASSEMBLER
 123
 124 extern segment_info_type *seg_info (segT);
 125 extern symbolS *section_symbol (segT);
 126
 127 #else /* ! BFD_ASSEMBLER */
 128
 129 #ifdef MANY_SEGMENTS
 130
 131 extern segment_info_type segment_info[];
 132
 133 #define seg_info(SEC)   (&segment_info[SEC])
 134
 135 #else
 136
 137 /* Sentinel for frchain crawling.  Points to the 1st data-segment
 138    frchain.  (Which is pointed to by the last text-segment frchain.) */
 139 extern frchainS *data0_frchainP;
 140 extern frchainS *bss0_frchainP;
 141
 142 #define seg_info(S)     (abort (), (segment_info_type *) 0)
 143
 144 #endif
 145
 146 #endif /* ! BFD_ASSEMBLER */
 147
 148 extern void subsegs_print_statistics (FILE *);