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   /* The default -fmath-errno, -fsigned-zeros and -ftrapping-math change
 119      depending on the language (they can be disabled by the Ada and Java
 120      front-ends).  Pass thru conservative standard settings.  */
 121   if (!global_options_set.x_flag_errno_math)
 122     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 123                                    global_options.x_flag_errno_math
 124                                    ? "-fmath-errno"
 125                                    : "-fno-math-errno");
 126   if (!global_options_set.x_flag_signed_zeros)
 127     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 128                                    global_options.x_flag_signed_zeros
 129                                    ? "-fsigned-zeros"
 130                                    : "-fno-signed-zeros");
 131   if (!global_options_set.x_flag_trapping_math)
 132     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 133                                    global_options.x_flag_trapping_math
 134                                    ? "-ftrapping-math"
 135                                    : "-fno-trapping-math");
 136   /* We need to merge -f[no-]strict-overflow, -f[no-]wrapv and -f[no-]trapv
 137      conservatively, so stream out their defaults.  */
 138   if (!global_options_set.x_flag_wrapv
 139       && global_options.x_flag_wrapv)
 140     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fwrapv");
 141   if (!global_options_set.x_flag_trapv
 142       && !global_options.x_flag_trapv)
 143     append_to_collect_gcc_options (&temporary_obstack, &first_p, "-fno-trapv");
 144   if (!global_options_set.x_flag_strict_overflow
 145       && !global_options.x_flag_strict_overflow)
 146     append_to_collect_gcc_options (&temporary_obstack, &first_p,
 147                                "-fno-strict-overflow");
 148
 149   /* Output explicitly passed options.  */
 150   for (i = 1; i < save_decoded_options_count; ++i)
 151     {
 152       struct cl_decoded_option *option = &save_decoded_options[i];
 153
 154       /* Skip explicitly some common options that we do not need.  */
 155       switch (option->opt_index)
 156       {
 157         case OPT_dumpbase:
 158         case OPT_SPECIAL_unknown:
 159         case OPT_SPECIAL_ignore:
 160         case OPT_SPECIAL_program_name:
 161         case OPT_SPECIAL_input_file:
 162           continue;
 163
 164         default:
 165           break;
 166       }
 167
 168       /* Skip frontend and driver specific options here.  */
 169       if (!(cl_options[option->opt_index].flags & (CL_COMMON|CL_TARGET|CL_LTO)))
 170         continue;
 171
 172       /* Drop options created from the gcc driver that will be rejected
 173          when passed on to the driver again.  */
 174       if (cl_options[option->opt_index].cl_reject_driver)
 175         continue;
 176
 177       /* Also drop all options that are handled by the driver as well,
 178          which includes things like -o and -v or -fhelp for example.
 179          We do not need those.  Also drop all diagnostic options.  */
 180       if (cl_options[option->opt_index].flags & (CL_DRIVER|CL_WARNING))
 181         continue;
 182
 183       for (j = 0; j < option->canonical_option_num_elements; ++j)
 184         append_to_collect_gcc_options (&temporary_obstack, &first_p,
 185                                        option->canonical_option[j]);
 186     }
 187   obstack_grow (&temporary_obstack, "\0", 1);
 188   args = XOBFINISH (&temporary_obstack, char *);
 189   lto_write_data (args, strlen (args) + 1);
 190   lto_end_section ();
 191
 192   obstack_free (&temporary_obstack, NULL);
 193   free (section_name);
 194 }