vxworks.c revision 1.8 
1/* Common VxWorks target definitions for GNU compiler.
2   Copyright (C) 2007-2017 Free Software Foundation, Inc.
3   Contributed by CodeSourcery, Inc.
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 3, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING3.  If not see
19<http://www.gnu.org/licenses/>.  */
20
21#include "config.h"
22#include "system.h"
23#include "coretypes.h"
24#include "target.h"
25#include "tree.h"
26#include "stringpool.h"
27#include "diagnostic-core.h"
28#include "output.h"
29#include "fold-const.h"
30
31/* Like default_named_section_asm_out_constructor, except that even
32   constructors with DEFAULT_INIT_PRIORITY must go in a numbered
33   section on VxWorks.  The VxWorks runtime uses a clever trick to get
34   the sentinel entry (-1) inserted at the beginning of the .ctors
35   segment.  This trick will not work if we ever generate any entries
36   in plain .ctors sections; we must always use .ctors.PRIORITY.  */
37
38void
39vxworks_asm_out_constructor (rtx symbol, int priority)
40{
41  section *sec;
42
43  sec = get_cdtor_priority_section (priority,
44				    /*constructor_p=*/true);
45  assemble_addr_to_section (symbol, sec);
46}
47
48/* See comment for vxworks_asm_out_constructor.  */
49
50void
51vxworks_asm_out_destructor (rtx symbol, int priority)
52{
53  section *sec;
54
55  sec = get_cdtor_priority_section (priority,
56				    /*constructor_p=*/false);
57  assemble_addr_to_section (symbol, sec);
58}
59
60/* Return the list of FIELD_DECLs that make up an emulated TLS
61   variable's control object.  TYPE is the structure these are fields
62   of and *NAME will be filled in with the structure tag that should
63   be used.  */
64
65static tree
66vxworks_emutls_var_fields (tree type, tree *name)
67{
68  tree field, next_field;
69
70  *name = get_identifier ("__tls_var");
71
72  field = build_decl (BUILTINS_LOCATION, FIELD_DECL,
73		      get_identifier ("size"), unsigned_type_node);
74  DECL_CONTEXT (field) = type;
75  next_field = field;
76
77  field = build_decl (BUILTINS_LOCATION, FIELD_DECL,
78		      get_identifier ("module_id"), unsigned_type_node);
79  DECL_CONTEXT (field) = type;
80  DECL_CHAIN (field) = next_field;
81  next_field = field;
82
83  field = build_decl (BUILTINS_LOCATION, FIELD_DECL,
84		      get_identifier ("offset"), unsigned_type_node);
85  DECL_CONTEXT (field) = type;
86  DECL_CHAIN (field) = next_field;
87
88  return field;
89}
90
91/* Return the CONSTRUCTOR to initialize an emulated TLS control
92   object.  VAR is the control object.  DECL is the TLS object itself
93   and TMPL_ADDR is the address (an ADDR_EXPR) of the initializer for
94   that object.  */
95
96static tree
97vxworks_emutls_var_init (tree var, tree decl, tree tmpl_addr)
98{
99  vec<constructor_elt, va_gc> *v;
100  vec_alloc (v, 3);
101
102  tree type = TREE_TYPE (var);
103  tree field = TYPE_FIELDS (type);
104
105  constructor_elt elt = {field, fold_convert (TREE_TYPE (field), tmpl_addr)};
106  v->quick_push (elt);
107
108  field = DECL_CHAIN (field);
109  elt.index = field;
110  elt.value = build_int_cst (TREE_TYPE (field), 0);
111  v->quick_push (elt);
112
113  field = DECL_CHAIN (field);
114  elt.index = field;
115  elt.value = fold_convert (TREE_TYPE (field), DECL_SIZE_UNIT (decl));
116  v->quick_push (elt);
117
118  return build_constructor (type, v);
119}
120
121/* Do VxWorks-specific parts of TARGET_OPTION_OVERRIDE.  */
122
123void
124vxworks_override_options (void)
125{
126  /* We don't support __thread via target hooks.  */
127  targetm.have_tls = false;
128
129  targetm.emutls.get_address = "__builtin___tls_lookup";
130  targetm.emutls.register_common = NULL;
131  targetm.emutls.var_section = ".tls_vars";
132  targetm.emutls.tmpl_section = ".tls_data";
133  targetm.emutls.var_prefix = "__tls__";
134  targetm.emutls.tmpl_prefix = "";
135  targetm.emutls.var_fields = vxworks_emutls_var_fields;
136  targetm.emutls.var_init = vxworks_emutls_var_init;
137  targetm.emutls.var_align_fixed = true;
138  targetm.emutls.debug_form_tls_address = true;
139
140  /* We can use .ctors/.dtors sections only in RTP mode.  */
141  targetm.have_ctors_dtors = TARGET_VXWORKS_RTP;
142
143  /* PIC is only supported for RTPs.  */
144  if (flag_pic && !TARGET_VXWORKS_RTP)
145    error ("PIC is only supported for RTPs");
146
147  /* Default to strict dwarf-2 to prevent potential difficulties observed with
148     non-gdb debuggers on extensions > 2.  */
149  if (!global_options_set.x_dwarf_strict)
150    dwarf_strict = 1;
151
152  if (!global_options_set.x_dwarf_version)
153    dwarf_version = 2;
154}
155