gcc/go/go-backend.c

   1 /* go-backend.c -- Go frontend interface to gcc backend.
   2    Copyright (C) 2010-2014 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 "simple-object.h"
  24 #include "tm.h"
  25 #include "tree.h"
  26 #include "stor-layout.h"
  27 #include "tm_p.h"
  28 #include "intl.h"
  29 #include "output.h"     /* for assemble_string */
  30 #include "target.h"
  31 #include "common/common-target.h"
  32 #include "diagnostic.h"
  33
  34 #include "go-c.h"
  35
  36 /* The segment name we pass to simple_object_start_read to find Go
  37    export data.  */
  38
  39 #ifndef GO_EXPORT_SEGMENT_NAME
  40 #define GO_EXPORT_SEGMENT_NAME "__GNU_GO"
  41 #endif
  42
  43 /* The section name we use when reading and writing export data.  */
  44
  45 #ifndef GO_EXPORT_SECTION_NAME
  46 #define GO_EXPORT_SECTION_NAME ".go_export"
  47 #endif
  48
  49 /* This file holds all the cases where the Go frontend needs
  50    information from gcc's backend.  */
  51
  52 /* Return whether or not GCC has reported any errors.  */
  53
  54 bool
  55 saw_errors (void)
  56 {
  57   return errorcount != 0 || sorrycount != 0;
  58 }
  59
  60 /* Return the alignment in bytes of a struct field of type T.  */
  61
  62 unsigned int
  63 go_field_alignment (tree t)
  64 {
  65   unsigned int v;
  66
  67   v = TYPE_ALIGN (t);
  68
  69 #ifdef BIGGEST_FIELD_ALIGNMENT
  70   if (v > BIGGEST_FIELD_ALIGNMENT)
  71     v = BIGGEST_FIELD_ALIGNMENT;
  72 #endif
  73
  74 #ifdef ADJUST_FIELD_ALIGN
  75   {
  76     tree field ATTRIBUTE_UNUSED;
  77     field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL, t);
  78     v = ADJUST_FIELD_ALIGN (field, v);
  79   }
  80 #endif
  81
  82   return v / BITS_PER_UNIT;
  83 }
  84
  85 /* Return the size and alignment of a trampoline.  */
  86
  87 void
  88 go_trampoline_info (unsigned int *size, unsigned int *alignment)
  89 {
  90   *size = TRAMPOLINE_SIZE;
  91   *alignment = TRAMPOLINE_ALIGNMENT;
  92 }
  93
  94 /* This is called by the Go frontend proper if the unsafe package was
  95    imported.  When that happens we can not do type-based alias
  96    analysis.  */
  97
  98 void
  99 go_imported_unsafe (void)
 100 {
 101   flag_strict_aliasing = false;
 102
 103   /* Let the backend know that the options have changed.  */
 104   targetm.override_options_after_change ();
 105 }
 106
 107 /* This is called by the Go frontend proper to add data to the
 108    section containing Go export data.  */
 109
 110 void
 111 go_write_export_data (const char *bytes, unsigned int size)
 112 {
 113   static section* sec;
 114
 115   if (sec == NULL)
 116     {
 117       gcc_assert (targetm_common.have_named_sections);
 118       sec = get_section (GO_EXPORT_SECTION_NAME, SECTION_DEBUG, NULL);
 119     }
 120
 121   switch_to_section (sec);
 122   assemble_string (bytes, size);
 123 }
 124
 125 /* The go_read_export_data function is called by the Go frontend
 126    proper to read Go export data from an object file.  FD is a file
 127    descriptor open for reading.  OFFSET is the offset within the file
 128    where the object file starts; this will be 0 except when reading an
 129    archive.  On success this returns NULL and sets *PBUF to a buffer
 130    allocated using malloc, of size *PLEN, holding the export data.  If
 131    the data is not found, this returns NULL and sets *PBUF to NULL and
 132    *PLEN to 0.  If some error occurs, this returns an error message
 133    and sets *PERR to an errno value or 0 if there is no relevant
 134    errno.  */
 135
 136 const char *
 137 go_read_export_data (int fd, off_t offset, char **pbuf, size_t *plen,
 138                      int *perr)
 139 {
 140   simple_object_read *sobj;
 141   const char *errmsg;
 142   off_t sec_offset;
 143   off_t sec_length;
 144   int found;
 145   char *buf;
 146   ssize_t c;
 147
 148   *pbuf = NULL;
 149   *plen = 0;
 150
 151   sobj = simple_object_start_read (fd, offset, GO_EXPORT_SEGMENT_NAME,
 152                                    &errmsg, perr);
 153   if (sobj == NULL)
 154     {
 155       /* If we get an error here, just pretend that we didn't find any
 156          export data.  This is the right thing to do if the error is
 157          that the file was not recognized as an object file.  This
 158          will ignore file I/O errors, but it's not too big a deal
 159          because we will wind up giving some other error later.  */
 160       return NULL;
 161     }
 162
 163   found = simple_object_find_section (sobj, GO_EXPORT_SECTION_NAME,
 164                                       &sec_offset, &sec_length,
 165                                       &errmsg, perr);
 166   simple_object_release_read (sobj);
 167   if (!found)
 168     return errmsg;
 169
 170   if (lseek (fd, offset + sec_offset, SEEK_SET) < 0)
 171     {
 172       *perr = errno;
 173       return _("lseek failed while reading export data");
 174     }
 175
 176   buf = XNEWVEC (char, sec_length);
 177   if (buf == NULL)
 178     {
 179       *perr = errno;
 180       return _("memory allocation failed while reading export data");
 181     }
 182
 183   c = read (fd, buf, sec_length);
 184   if (c < 0)
 185     {
 186       *perr = errno;
 187       free (buf);
 188       return _("read failed while reading export data");
 189     }
 190
 191   if (c < sec_length)
 192     {
 193       free (buf);
 194       return _("short read while reading export data");
 195     }
 196
 197   *pbuf = buf;
 198   *plen = sec_length;
 199
 200   return NULL;
 201 }