subsegs.h revision 77298 
1/* subsegs.h -> subsegs.c
2   Copyright (C) 1987, 92, 93, 94, 95, 96, 98, 2000
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, 59 Temple Place - Suite 330, Boston, MA
20   02111-1307, 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
43struct 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
58typedef struct frchain frchainS;
59
60/* All subsegments' chains hang off here.  NULL means no frchains yet.  */
61extern 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.  */
65extern frchainS *frchain_now;
66
67typedef 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
124extern segment_info_type *seg_info PARAMS ((segT));
125extern symbolS *section_symbol PARAMS ((segT));
126
127#else /* ! BFD_ASSEMBLER */
128
129#ifdef MANY_SEGMENTS
130
131extern 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.) */
139extern frchainS *data0_frchainP;
140extern frchainS *bss0_frchainP;
141
142/* Dummy so stuff can compile.  Should never be used.  */
143struct seg_info_trash {
144  struct {
145    unsigned stab_string_size : 1;
146  } stabu;
147  unsigned hadone : 1;
148};
149#define seg_info(S)	(abort (), (struct seg_info_trash *) 0)
150
151#endif
152
153#endif /* ! BFD_ASSEMBLER */
154
155extern void subsegs_print_statistics PARAMS ((FILE *));
156