1 /* go-backend.c -- Go frontend interface to gcc backend.
2 Copyright (C) 2010-2021 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "target.h"
24 #include "tree.h"
25 #include "memmodel.h"
26 #include "tm_p.h"
27 #include "diagnostic.h"
28 #include "simple-object.h"
29 #include "stor-layout.h"
30 #include "intl.h"
31 #include "output.h" /* for assemble_string */
32 #include "common/common-target.h"
33 #include "go-c.h"
34
35 /* The segment name we pass to simple_object_start_read to find Go
36 export data. */
37
38 #ifndef GO_EXPORT_SEGMENT_NAME
39 #define GO_EXPORT_SEGMENT_NAME "__GNU_GO"
40 #endif
41
42 /* The section name we use when reading and writing export data. */
43
44 #ifndef GO_EXPORT_SECTION_NAME
45 #define GO_EXPORT_SECTION_NAME ".go_export"
46 #endif
47
48 #ifndef TARGET_AIX
49 #define TARGET_AIX 0
50 #endif
51
52 /* This file holds all the cases where the Go frontend needs
53 information from gcc's backend. */
54
55 /* Return whether or not GCC has reported any errors. */
56
57 bool
saw_errors(void)58 saw_errors (void)
59 {
60 return errorcount != 0 || sorrycount != 0;
61 }
62
63 /* Return the alignment in bytes of a struct field of type T. */
64
65 unsigned int
go_field_alignment(tree t)66 go_field_alignment (tree t)
67 {
68 unsigned int v;
69
70 v = TYPE_ALIGN (t);
71
72 #ifdef BIGGEST_FIELD_ALIGNMENT
73 if (v > BIGGEST_FIELD_ALIGNMENT)
74 v = BIGGEST_FIELD_ALIGNMENT;
75 #endif
76
77 #ifdef ADJUST_FIELD_ALIGN
78 v = ADJUST_FIELD_ALIGN (NULL_TREE, t, v);
79 #endif
80
81 return v / BITS_PER_UNIT;
82 }
83
84 /* This is called by the Go frontend proper if the unsafe package was
85 imported. When that happens we cannot do type-based alias
86 analysis. */
87
88 void
go_imported_unsafe(void)89 go_imported_unsafe (void)
90 {
91 flag_strict_aliasing = false;
92 TREE_OPTIMIZATION (optimization_default_node)->x_flag_strict_aliasing = false;
93
94 /* Let the backend know that the options have changed. */
95 targetm.override_options_after_change ();
96 }
97
98 /* This is called by the Go frontend proper to add data to the
99 section containing Go export data. */
100
101 void
go_write_export_data(const char * bytes,unsigned int size)102 go_write_export_data (const char *bytes, unsigned int size)
103 {
104 static section* sec;
105
106 if (sec == NULL)
107 {
108 gcc_assert (targetm_common.have_named_sections);
109 sec = get_section (GO_EXPORT_SECTION_NAME,
110 TARGET_AIX ? SECTION_EXCLUDE : SECTION_DEBUG,
111 NULL);
112 }
113
114 switch_to_section (sec);
115 assemble_string (bytes, size);
116 }
117
118 /* The go_read_export_data function is called by the Go frontend
119 proper to read Go export data from an object file. FD is a file
120 descriptor open for reading. OFFSET is the offset within the file
121 where the object file starts; this will be 0 except when reading an
122 archive. On success this returns NULL and sets *PBUF to a buffer
123 allocated using malloc, of size *PLEN, holding the export data. If
124 the data is not found, this returns NULL and sets *PBUF to NULL and
125 *PLEN to 0. If some error occurs, this returns an error message
126 and sets *PERR to an errno value or 0 if there is no relevant
127 errno. */
128
129 const char *
go_read_export_data(int fd,off_t offset,char ** pbuf,size_t * plen,int * perr)130 go_read_export_data (int fd, off_t offset, char **pbuf, size_t *plen,
131 int *perr)
132 {
133 simple_object_read *sobj;
134 const char *errmsg;
135 off_t sec_offset;
136 off_t sec_length;
137 int found;
138 char *buf;
139 ssize_t c;
140
141 *pbuf = NULL;
142 *plen = 0;
143
144 sobj = simple_object_start_read (fd, offset, GO_EXPORT_SEGMENT_NAME,
145 &errmsg, perr);
146 if (sobj == NULL)
147 {
148 /* If we get an error here, just pretend that we didn't find any
149 export data. This is the right thing to do if the error is
150 that the file was not recognized as an object file. This
151 will ignore file I/O errors, but it's not too big a deal
152 because we will wind up giving some other error later. */
153 return NULL;
154 }
155
156 found = simple_object_find_section (sobj, GO_EXPORT_SECTION_NAME,
157 &sec_offset, &sec_length,
158 &errmsg, perr);
159 simple_object_release_read (sobj);
160 if (!found)
161 return errmsg;
162
163 if (lseek (fd, offset + sec_offset, SEEK_SET) < 0)
164 {
165 *perr = errno;
166 return _("lseek failed while reading export data");
167 }
168
169 buf = XNEWVEC (char, sec_length);
170 if (buf == NULL)
171 {
172 *perr = errno;
173 return _("memory allocation failed while reading export data");
174 }
175
176 c = read (fd, buf, sec_length);
177 if (c < 0)
178 {
179 *perr = errno;
180 free (buf);
181 return _("read failed while reading export data");
182 }
183
184 if (c < sec_length)
185 {
186 free (buf);
187 return _("short read while reading export data");
188 }
189
190 *pbuf = buf;
191 *plen = sec_length;
192
193 return NULL;
194 }
195