subsegs.h revision 33965 
1/* subsegs.h -> subsegs.c
2   Copyright (C) 1987, 92, 93, 94, 95, 1996 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
18   the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
19
20/*
21 * For every sub-segment the user mentions in the ASsembler program,
22 * we make one struct frchain. Each sub-segment has exactly one struct frchain
23 * and vice versa.
24 *
25 * Struct frchain's are forward chained (in ascending order of sub-segment
26 * code number). The chain runs through frch_next of each subsegment.
27 * This makes it hard to find a subsegment's frags
28 * if programmer uses a lot of them. Most programs only use text0 and
29 * data0, so they don't suffer. At least this way:
30 * (1)	There are no "arbitrary" restrictions on how many subsegments
31 *	can be programmed;
32 * (2)	Subsegments' frchain-s are (later) chained together in the order in
33 *	which they are emitted for object file viz text then data.
34 *
35 * From each struct frchain dangles a chain of struct frags. The frags
36 * represent code fragments, for that sub-segment, forward chained.
37 */
38
39#include "obstack.h"
40
41struct frchain			/* control building of a frag chain */
42{				/* FRCH = FRagment CHain control */
43  struct frag *frch_root;	/* 1st struct frag in chain, or NULL */
44  struct frag *frch_last;	/* last struct frag in chain, or NULL */
45  struct frchain *frch_next;	/* next in chain of struct frchain-s */
46  segT frch_seg;		/* SEG_TEXT or SEG_DATA. */
47  subsegT frch_subseg;		/* subsegment number of this chain */
48#ifdef BFD_ASSEMBLER
49  fixS *fix_root;		/* Root of fixups for this subsegment.  */
50  fixS *fix_tail;		/* Last fixup for this subsegment.  */
51#endif
52  struct obstack frch_obstack;	/* for objects in this frag chain */
53  fragS *frch_frag_now;		/* frag_now for this subsegment */
54};
55
56typedef struct frchain frchainS;
57
58/* All subsegments' chains hang off here.  NULL means no frchains yet.  */
59extern frchainS *frchain_root;
60
61/* Frchain we are assembling into now.  That is, the current segment's
62   frag chain, even if it contains no (complete) frags. */
63extern frchainS *frchain_now;
64
65
66typedef struct
67{
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    {
107      /* Current size of section holding stabs strings.  */
108      unsigned long stab_string_size;
109      /* Initial frag for ELF.  */
110      char *p;
111    }
112  stabu;
113
114#ifdef NEED_LITERAL_POOL
115  unsigned long literal_pool_size;
116#endif
117
118#ifdef TC_SEGMENT_INFO_TYPE
119  TC_SEGMENT_INFO_TYPE tc_segment_info_data;
120#endif
121} segment_info_type;
122
123#ifdef BFD_ASSEMBLER
124
125extern segment_info_type *seg_info PARAMS ((segT));
126extern symbolS *section_symbol PARAMS ((segT));
127
128#else /* ! BFD_ASSEMBLER */
129
130#ifdef MANY_SEGMENTS
131
132extern segment_info_type segment_info[];
133
134#define seg_info(SEC)	(&segment_info[SEC])
135
136#else
137
138/* Sentinel for frchain crawling.  Points to the 1st data-segment
139   frchain.  (Which is pointed to by the last text-segment frchain.) */
140extern frchainS *data0_frchainP;
141extern frchainS *bss0_frchainP;
142
143/* Dummy so stuff can compile.  Should never be used.  */
144struct seg_info_trash {
145  struct {
146    unsigned stab_string_size : 1;
147  } stabu;
148  unsigned hadone : 1;
149};
150#define seg_info(S)	(abort (), (struct seg_info_trash *) 0)
151
152#endif
153
154#endif /* ! BFD_ASSEMBLER */
155
156extern void subsegs_print_statistics PARAMS ((FILE *));
157
158/* end of subsegs.h */
159