gcc/lto-opts.c

   1 /* LTO IL options.
   2
   3    Copyright (C) 2009-2014 Free Software Foundation, Inc.
   4    Contributed by Simon Baldwin <simonb@google.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tree.h"
  26 #include "basic-block.h"
  27 #include "tree-ssa-alias.h"
  28 #include "internal-fn.h"
  29 #include "gimple-expr.h"
  30 #include "is-a.h"
  31 #include "gimple.h"
  32 #include "hashtab.h"
  33 #include "bitmap.h"
  34 #include "flags.h"
  35 #include "opts.h"
  36 #include "options.h"
  37 #include "common/common-target.h"
  38 #include "diagnostic.h"
  39 #include "lto-streamer.h"
  40 #include "toplev.h"
  41
  42 /* Append the option piece OPT to the COLLECT_GCC_OPTIONS string
  43    set up by OB, appropriately quoted and separated by spaces
  44    (if !*FIRST_P).  */
  45
  46 static void
  47 append_to_collect_gcc_options (struct obstack *ob,
  48                                bool *first_p, const char *opt)
  49 {
  50   const char *p, *q = opt;
  51   if (!*first_p)
  52     obstack_grow (ob, " ", 1);
  53   obstack_grow (ob, "'", 1);
  54   while ((p = strchr (q, '\'')))
  55     {
  56       obstack_grow (ob, q, p - q);
  57       obstack_grow (ob, "'\\''", 4);
  58       q = ++p;
  59     }
  60   obstack_grow (ob, q, strlen (q));
  61   obstack_grow (ob, "'", 1);
  62   *first_p = false;
  63 }
  64
  65 /* Write currently held options to an LTO IL section.  */
  66
  67 void
  68 lto_write_options (void)
  69 {
  70   struct lto_output_stream stream;
  71   char *section_name;
  72   struct obstack temporary_obstack;
  73   unsigned int i, j;
  74   char *args;
  75   bool first_p = true;
  76
  77   section_name = lto_get_section_name (LTO_section_opts, NULL, NULL);
  78   lto_begin_section (section_name, false);
  79   memset (&stream, 0, sizeof (stream));
  80
  81   obstack_init (&temporary_obstack);
  82
  83   /* Output options that affect GIMPLE IL semantics and are implicitly
  84      enabled by the frontend.
  85      This for now includes an explicit set of options that we also handle
  86      explicitly in lto-wrapper.c.  In the end the effects on GIMPLE IL
  87      semantics should be explicitely encoded in the IL or saved per
  88      function rather than per compilation unit.  */
  89   /* -fexceptions causes the EH machinery to be initialized, enabling
  90      generation of unwind data so that explicit throw() calls work.  */
  91   if (!global_options_set.x_flag_exceptions
  92       && global_options.x_flag_exceptions)
  93     append_to_collect_gcc_options (&temporary_obstack, &first_p,
  94                                    "-fexceptions");
  95   /* -fnon-call-exceptions changes the generation of exception
  96       regions.  It is enabled implicitly by the Go frontend.  */
  97   if (!global_options_set.x_flag_non_call_exceptions
  98       && global_options.x_flag_non_call_exceptions)
  99     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 100                                    "-fnon-call-exceptions");
 101   /* The default -ffp-contract changes depending on the language
 102      standard.  Pass thru conservative standard settings.  */
 103   if (!global_options_set.x_flag_fp_contract_mode)
 104     switch (global_options.x_flag_fp_contract_mode)
 105       {
 106       case FP_CONTRACT_OFF:
 107         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 108                                        "-ffp-contract=off");
 109         break;
 110       case FP_CONTRACT_ON:
 111         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 112                                        "-ffp-contract=on");
 113         break;
 114       case FP_CONTRACT_FAST:
 115         /* Nothing.  That merges conservatively and is the default for LTO.  */
 116         break;
 117       default:
 118         gcc_unreachable ();
 119       }
 120
 121   /* Output explicitly passed options.  */
 122   for (i = 1; i < save_decoded_options_count; ++i)
 123     {
 124       struct cl_decoded_option *option = &save_decoded_options[i];
 125
 126       /* Skip explicitly some common options that we do not need.  */
 127       switch (option->opt_index)
 128       {
 129         case OPT_dumpbase:
 130         case OPT_SPECIAL_unknown:
 131         case OPT_SPECIAL_ignore:
 132         case OPT_SPECIAL_program_name:
 133         case OPT_SPECIAL_input_file:
 134           continue;
 135
 136         default:
 137           break;
 138       }
 139
 140       /* Skip frontend and driver specific options here.  */
 141       if (!(cl_options[option->opt_index].flags & (CL_COMMON|CL_TARGET|CL_LTO)))
 142         continue;
 143
 144       /* Drop options created from the gcc driver that will be rejected
 145          when passed on to the driver again.  */
 146       if (cl_options[option->opt_index].cl_reject_driver)
 147         continue;
 148
 149       /* Also drop all options that are handled by the driver as well,
 150          which includes things like -o and -v or -fhelp for example.
 151          We do not need those.  Also drop all diagnostic options.  */
 152       if (cl_options[option->opt_index].flags & (CL_DRIVER|CL_WARNING))
 153         continue;
 154
 155       for (j = 0; j < option->canonical_option_num_elements; ++j)
 156         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 157                                        option->canonical_option[j]);
 158     }
 159   obstack_grow (&temporary_obstack, "\0", 1);
 160   args = XOBFINISH (&temporary_obstack, char *);
 161   lto_output_data_stream (&stream, args, strlen (args) + 1);
 162
 163   lto_write_stream (&stream);
 164   lto_end_section ();
 165
 166   obstack_free (&temporary_obstack, NULL);
 167   free (section_name);
 168 }