gcc/lto-opts.c

   1 /* LTO IL options.
   2
   3    Copyright (C) 2009-2017 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 "backend.h"
  26 #include "target.h"
  27 #include "tree.h"
  28 #include "gimple.h"
  29 #include "cgraph.h"
  30 #include "lto-streamer.h"
  31 #include "opts.h"
  32 #include "toplev.h"
  33
  34 /* Append the option piece OPT to the COLLECT_GCC_OPTIONS string
  35    set up by OB, appropriately quoted and separated by spaces
  36    (if !*FIRST_P).  */
  37
  38 static void
  39 append_to_collect_gcc_options (struct obstack *ob,
  40                                bool *first_p, const char *opt)
  41 {
  42   const char *p, *q = opt;
  43   if (!*first_p)
  44     obstack_grow (ob, " ", 1);
  45   obstack_grow (ob, "'", 1);
  46   while ((p = strchr (q, '\'')))
  47     {
  48       obstack_grow (ob, q, p - q);
  49       obstack_grow (ob, "'\\''", 4);
  50       q = ++p;
  51     }
  52   obstack_grow (ob, q, strlen (q));
  53   obstack_grow (ob, "'", 1);
  54   *first_p = false;
  55 }
  56
  57 /* Write currently held options to an LTO IL section.  */
  58
  59 void
  60 lto_write_options (void)
  61 {
  62   char *section_name;
  63   struct obstack temporary_obstack;
  64   unsigned int i, j;
  65   char *args;
  66   bool first_p = true;
  67
  68   section_name = lto_get_section_name (LTO_section_opts, NULL, NULL);
  69   lto_begin_section (section_name, false);
  70
  71   obstack_init (&temporary_obstack);
  72
  73   /* Output options that affect GIMPLE IL semantics and are implicitly
  74      enabled by the frontend.
  75      This for now includes an explicit set of options that we also handle
  76      explicitly in lto-wrapper.c.  In the end the effects on GIMPLE IL
  77      semantics should be explicitely encoded in the IL or saved per
  78      function rather than per compilation unit.  */
  79   /* -fexceptions causes the EH machinery to be initialized, enabling
  80      generation of unwind data so that explicit throw() calls work.  */
  81   if (!global_options_set.x_flag_exceptions
  82       && global_options.x_flag_exceptions)
  83     append_to_collect_gcc_options (&temporary_obstack, &first_p,
  84                                    "-fexceptions");
  85   /* -fnon-call-exceptions changes the generation of exception
  86       regions.  It is enabled implicitly by the Go frontend.  */
  87   if (!global_options_set.x_flag_non_call_exceptions
  88       && global_options.x_flag_non_call_exceptions)
  89     append_to_collect_gcc_options (&temporary_obstack, &first_p,
  90                                    "-fnon-call-exceptions");
  91   /* The default -ffp-contract changes depending on the language
  92      standard.  Pass thru conservative standard settings.  */
  93   if (!global_options_set.x_flag_fp_contract_mode)
  94     switch (global_options.x_flag_fp_contract_mode)
  95       {
  96       case FP_CONTRACT_OFF:
  97         append_to_collect_gcc_options (&temporary_obstack, &first_p,
  98                                        "-ffp-contract=off");
  99         break;
 100       case FP_CONTRACT_ON:
 101         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 102                                        "-ffp-contract=on");
 103         break;
 104       case FP_CONTRACT_FAST:
 105         /* Nothing.  That merges conservatively and is the default for LTO.  */
 106         break;
 107       default:
 108         gcc_unreachable ();
 109       }
 110   /* The default -fmath-errno, -fsigned-zeros and -ftrapping-math change
 111      depending on the language (they can be disabled by the Ada front-end).
 112      Pass thru conservative standard settings.  */
 113   if (!global_options_set.x_flag_errno_math)
 114     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 115                                    global_options.x_flag_errno_math
 116                                    ? "-fmath-errno"
 117                                    : "-fno-math-errno");
 118   if (!global_options_set.x_flag_signed_zeros)
 119     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 120                                    global_options.x_flag_signed_zeros
 121                                    ? "-fsigned-zeros"
 122                                    : "-fno-signed-zeros");
 123   if (!global_options_set.x_flag_trapping_math)
 124     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 125                                    global_options.x_flag_trapping_math
 126                                    ? "-ftrapping-math"
 127                                    : "-fno-trapping-math");
 128   /* We need to merge -f[no-]strict-overflow, -f[no-]wrapv and -f[no-]trapv
 129      conservatively, so stream out their defaults.  */
 130   if (!global_options_set.x_flag_wrapv
 131       && global_options.x_flag_wrapv)
 132     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fwrapv");
 133   if (!global_options_set.x_flag_trapv
 134       && !global_options.x_flag_trapv)
 135     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fno-trapv");
 136
 137   if (!global_options_set.x_flag_openmp
 138       && !global_options.x_flag_openmp)
 139     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fno-openmp");
 140   if (!global_options_set.x_flag_openacc
 141       && !global_options.x_flag_openacc)
 142     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 143                                    "-fno-openacc");
 144
 145   /* Append options from target hook and store them to offload_lto section.  */
 146   if (lto_stream_offload_p)
 147     {
 148       char *offload_opts = targetm.offload_options ();
 149       char *offload_ptr = offload_opts;
 150       while (offload_ptr)
 151        {
 152          char *next = strchr (offload_ptr, ' ');
 153          if (next)
 154            *next++ = '\0';
 155          append_to_collect_gcc_options (&temporary_obstack, &first_p,
 156                                         offload_ptr);
 157          offload_ptr = next;
 158        }
 159       free (offload_opts);
 160     }
 161
 162   /* Output explicitly passed options.  */
 163   for (i = 1; i < save_decoded_options_count; ++i)
 164     {
 165       struct cl_decoded_option *option = &save_decoded_options[i];
 166
 167       /* Skip explicitly some common options that we do not need.  */
 168       switch (option->opt_index)
 169       {
 170         case OPT_dumpbase:
 171         case OPT_SPECIAL_unknown:
 172         case OPT_SPECIAL_ignore:
 173         case OPT_SPECIAL_program_name:
 174         case OPT_SPECIAL_input_file:
 175           continue;
 176
 177         default:
 178           break;
 179       }
 180
 181       /* Skip frontend and driver specific options here.  */
 182       if (!(cl_options[option->opt_index].flags & (CL_COMMON|CL_TARGET|CL_LTO)))
 183         continue;
 184
 185       /* Do not store target-specific options in offload_lto section.  */
 186       if ((cl_options[option->opt_index].flags & CL_TARGET)
 187           && lto_stream_offload_p)
 188        continue;
 189
 190       /* Drop options created from the gcc driver that will be rejected
 191          when passed on to the driver again.  */
 192       if (cl_options[option->opt_index].cl_reject_driver)
 193         continue;
 194
 195       /* Also drop all options that are handled by the driver as well,
 196          which includes things like -o and -v or -fhelp for example.
 197          We do not need those.  The only exception is -foffload option, if we
 198          write it in offload_lto section.  Also drop all diagnostic options.  */
 199       if ((cl_options[option->opt_index].flags & (CL_DRIVER|CL_WARNING))
 200           && (!lto_stream_offload_p || option->opt_index != OPT_foffload_))
 201         continue;
 202
 203       for (j = 0; j < option->canonical_option_num_elements; ++j)
 204         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 205                                        option->canonical_option[j]);
 206     }
 207   obstack_grow (&temporary_obstack, "\0", 1);
 208   args = XOBFINISH (&temporary_obstack, char *);
 209   lto_write_data (args, strlen (args) + 1);
 210   lto_end_section ();
 211
 212   obstack_free (&temporary_obstack, NULL);
 213   free (section_name);
 214 }