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   char *section_name;
  71   struct obstack temporary_obstack;
  72   unsigned int i, j;
  73   char *args;
  74   bool first_p = true;
  75
  76   section_name = lto_get_section_name (LTO_section_opts, NULL, NULL);
  77   lto_begin_section (section_name, false);
  78
  79   obstack_init (&temporary_obstack);
  80
  81   /* Output options that affect GIMPLE IL semantics and are implicitly
  82      enabled by the frontend.
  83      This for now includes an explicit set of options that we also handle
  84      explicitly in lto-wrapper.c.  In the end the effects on GIMPLE IL
  85      semantics should be explicitely encoded in the IL or saved per
  86      function rather than per compilation unit.  */
  87   /* -fexceptions causes the EH machinery to be initialized, enabling
  88      generation of unwind data so that explicit throw() calls work.  */
  89   if (!global_options_set.x_flag_exceptions
  90       && global_options.x_flag_exceptions)
  91     append_to_collect_gcc_options (&temporary_obstack, &first_p,
  92                                    "-fexceptions");
  93   /* -fnon-call-exceptions changes the generation of exception
  94       regions.  It is enabled implicitly by the Go frontend.  */
  95   if (!global_options_set.x_flag_non_call_exceptions
  96       && global_options.x_flag_non_call_exceptions)
  97     append_to_collect_gcc_options (&temporary_obstack, &first_p,
  98                                    "-fnon-call-exceptions");
  99   /* The default -ffp-contract changes depending on the language
 100      standard.  Pass thru conservative standard settings.  */
 101   if (!global_options_set.x_flag_fp_contract_mode)
 102     switch (global_options.x_flag_fp_contract_mode)
 103       {
 104       case FP_CONTRACT_OFF:
 105         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 106                                        "-ffp-contract=off");
 107         break;
 108       case FP_CONTRACT_ON:
 109         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 110                                        "-ffp-contract=on");
 111         break;
 112       case FP_CONTRACT_FAST:
 113         /* Nothing.  That merges conservatively and is the default for LTO.  */
 114         break;
 115       default:
 116         gcc_unreachable ();
 117       }
 118   /* We need to merge -f[no-]strict-overflow, -f[no-]wrapv and -f[no-]trapv
 119      conservatively, so stream out their defaults.  */
 120   if (!global_options_set.x_flag_wrapv
 121       && global_options.x_flag_wrapv)
 122     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fwrapv");
 123   if (!global_options_set.x_flag_trapv
 124       && !global_options.x_flag_trapv)
 125     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fno-trapv");
 126   if (!global_options_set.x_flag_strict_overflow
 127       && !global_options.x_flag_strict_overflow)
 128     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 129                                "-fno-strict-overflow");
 130
 131   /* Output explicitly passed options.  */
 132   for (i = 1; i < save_decoded_options_count; ++i)
 133     {
 134       struct cl_decoded_option *option = &save_decoded_options[i];
 135
 136       /* Skip explicitly some common options that we do not need.  */
 137       switch (option->opt_index)
 138       {
 139         case OPT_dumpbase:
 140         case OPT_SPECIAL_unknown:
 141         case OPT_SPECIAL_ignore:
 142         case OPT_SPECIAL_program_name:
 143         case OPT_SPECIAL_input_file:
 144           continue;
 145
 146         default:
 147           break;
 148       }
 149
 150       /* Skip frontend and driver specific options here.  */
 151       if (!(cl_options[option->opt_index].flags & (CL_COMMON|CL_TARGET|CL_LTO)))
 152         continue;
 153
 154       /* Drop options created from the gcc driver that will be rejected
 155          when passed on to the driver again.  */
 156       if (cl_options[option->opt_index].cl_reject_driver)
 157         continue;
 158
 159       /* Also drop all options that are handled by the driver as well,
 160          which includes things like -o and -v or -fhelp for example.
 161          We do not need those.  Also drop all diagnostic options.  */
 162       if (cl_options[option->opt_index].flags & (CL_DRIVER|CL_WARNING))
 163         continue;
 164
 165       for (j = 0; j < option->canonical_option_num_elements; ++j)
 166         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 167                                        option->canonical_option[j]);
 168     }
 169   obstack_grow (&temporary_obstack, "\0", 1);
 170   args = XOBFINISH (&temporary_obstack, char *);
 171   lto_write_data (args, strlen (args) + 1);
 172   lto_end_section ();
 173
 174   obstack_free (&temporary_obstack, NULL);
 175   free (section_name);
 176 }