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   /* We need to merge -f[no-]strict-overflow, -f[no-]wrapv and -f[no-]trapv
 121      conservatively, so stream out their defaults.  */
 122   if (!global_options_set.x_flag_wrapv
 123       && global_options.x_flag_wrapv)
 124     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fwrapv");
 125   if (!global_options_set.x_flag_trapv
 126       && !global_options.x_flag_trapv)
 127     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fno-trapv");
 128   if (!global_options_set.x_flag_strict_overflow
 129       && !global_options.x_flag_strict_overflow)
 130     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 131                                "-fno-strict-overflow");
 132
 133   /* Output explicitly passed options.  */
 134   for (i = 1; i < save_decoded_options_count; ++i)
 135     {
 136       struct cl_decoded_option *option = &save_decoded_options[i];
 137
 138       /* Skip explicitly some common options that we do not need.  */
 139       switch (option->opt_index)
 140       {
 141         case OPT_dumpbase:
 142         case OPT_SPECIAL_unknown:
 143         case OPT_SPECIAL_ignore:
 144         case OPT_SPECIAL_program_name:
 145         case OPT_SPECIAL_input_file:
 146           continue;
 147
 148         default:
 149           break;
 150       }
 151
 152       /* Skip frontend and driver specific options here.  */
 153       if (!(cl_options[option->opt_index].flags & (CL_COMMON|CL_TARGET|CL_LTO)))
 154         continue;
 155
 156       /* Drop options created from the gcc driver that will be rejected
 157          when passed on to the driver again.  */
 158       if (cl_options[option->opt_index].cl_reject_driver)
 159         continue;
 160
 161       /* Also drop all options that are handled by the driver as well,
 162          which includes things like -o and -v or -fhelp for example.
 163          We do not need those.  Also drop all diagnostic options.  */
 164       if (cl_options[option->opt_index].flags & (CL_DRIVER|CL_WARNING))
 165         continue;
 166
 167       for (j = 0; j < option->canonical_option_num_elements; ++j)
 168         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 169                                        option->canonical_option[j]);
 170     }
 171   obstack_grow (&temporary_obstack, "\0", 1);
 172   args = XOBFINISH (&temporary_obstack, char *);
 173   lto_output_data_stream (&stream, args, strlen (args) + 1);
 174
 175   lto_write_stream (&stream);
 176   lto_end_section ();
 177
 178   obstack_free (&temporary_obstack, NULL);
 179   free (section_name);
 180 }