gas/subsegs.h

   1 /* subsegs.h -> subsegs.c
   2    Copyright (C) 1987-2016 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 3, 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, 51 Franklin Street - Fifth Floor, Boston, MA
  19    02110-1301, 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 frch_cfi_data;
  43
  44 struct frchain                  /* control building of a frag chain */
  45 {                               /* FRCH = FRagment CHain control */
  46   struct frag *frch_root;       /* 1st struct frag in chain, or NULL */
  47   struct frag *frch_last;       /* last struct frag in chain, or NULL */
  48   struct frchain *frch_next;    /* next in chain of struct frchain-s */
  49   subsegT frch_subseg;          /* subsegment number of this chain */
  50   fixS *fix_root;               /* Root of fixups for this subsegment.  */
  51   fixS *fix_tail;               /* Last fixup for this subsegment.  */
  52   struct obstack frch_obstack;  /* for objects in this frag chain */
  53   fragS *frch_frag_now;         /* frag_now for this subsegment */
  54   struct frch_cfi_data *frch_cfi_data;
  55 };
  56
  57 typedef struct frchain frchainS;
  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 typedef struct segment_info_struct {
  64   frchainS *frchainP;
  65   unsigned int hadone : 1;
  66
  67   /* This field is set if this is a .bss section which does not really
  68      have any contents.  Once upon a time a .bss section did not have
  69      any frags, but that is no longer true.  This field prevent the
  70      SEC_HAS_CONTENTS flag from being set for the section even if
  71      there are frags.  */
  72   unsigned int bss : 1;
  73
  74   int user_stuff;
  75
  76   /* Fixups for this segment.  This is only valid after the frchains
  77      are run together.  */
  78   fixS *fix_root;
  79   fixS *fix_tail;
  80
  81   symbolS *dot;
  82
  83   struct lineno_list *lineno_list_head;
  84   struct lineno_list *lineno_list_tail;
  85
  86   /* Which BFD section does this gas segment correspond to?  */
  87   asection *bfd_section;
  88
  89   /* NULL, or pointer to the gas symbol that is the section symbol for
  90      this section.  sym->bsym and bfd_section->symbol should be the same.  */
  91   symbolS *sym;
  92
  93   /* Used by dwarf2dbg.c for this section's line table entries.  */
  94   void *dwarf2_line_seg;
  95
  96   union {
  97     /* Current size of section holding stabs strings.  */
  98     unsigned long stab_string_size;
  99     /* Initial frag for ELF.  */
 100     char *p;
 101   }
 102   stabu;
 103
 104 #ifdef NEED_LITERAL_POOL
 105   unsigned long literal_pool_size;
 106 #endif
 107
 108 #ifdef TC_SEGMENT_INFO_TYPE
 109   TC_SEGMENT_INFO_TYPE tc_segment_info_data;
 110 #endif
 111 } segment_info_type;
 112
 113
 114 #define seg_info(sec) \
 115   ((segment_info_type *) bfd_get_section_userdata (stdoutput, sec))
 116
 117 extern symbolS *section_symbol (segT);
 118
 119 extern void subsegs_print_statistics (FILE *);