gcc/opts-common.c

   1 /* Command line option handling.
   2    Copyright (C) 2006 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "intl.h"
  24 #include "coretypes.h"
  25 #include "opts.h"
  26
  27 /* Perform a binary search to find which option the command-line INPUT
  28    matches.  Returns its index in the option array, and N_OPTS
  29    (cl_options_count) on failure.
  30
  31    This routine is quite subtle.  A normal binary search is not good
  32    enough because some options can be suffixed with an argument, and
  33    multiple sub-matches can occur, e.g. input of "-pedantic" matching
  34    the initial substring of "-pedantic-errors".
  35
  36    A more complicated example is -gstabs.  It should match "-g" with
  37    an argument of "stabs".  Suppose, however, that the number and list
  38    of switches are such that the binary search tests "-gen-decls"
  39    before having tested "-g".  This doesn't match, and as "-gen-decls"
  40    is less than "-gstabs", it will become the lower bound of the
  41    binary search range, and "-g" will never be seen.  To resolve this
  42    issue, opts.sh makes "-gen-decls" point, via the back_chain member,
  43    to "-g" so that failed searches that end between "-gen-decls" and
  44    the lexicographically subsequent switch know to go back and see if
  45    "-g" causes a match (which it does in this example).
  46
  47    This search is done in such a way that the longest match for the
  48    front end in question wins.  If there is no match for the current
  49    front end, the longest match for a different front end is returned
  50    (or N_OPTS if none) and the caller emits an error message.  */
  51 size_t
  52 find_opt (const char *input, int lang_mask)
  53 {
  54   size_t mn, mx, md, opt_len;
  55   size_t match_wrong_lang;
  56   int comp;
  57
  58   mn = 0;
  59   mx = cl_options_count;
  60
  61   /* Find mn such this lexicographical inequality holds:
  62      cl_options[mn] <= input < cl_options[mn + 1].  */
  63   while (mx - mn > 1)
  64     {
  65       md = (mn + mx) / 2;
  66       opt_len = cl_options[md].opt_len;
  67       comp = strncmp (input, cl_options[md].opt_text + 1, opt_len);
  68
  69       if (comp < 0)
  70         mx = md;
  71       else
  72         mn = md;
  73     }
  74
  75   /* This is the switch that is the best match but for a different
  76      front end, or cl_options_count if there is no match at all.  */
  77   match_wrong_lang = cl_options_count;
  78
  79   /* Backtrace the chain of possible matches, returning the longest
  80      one, if any, that fits best.  With current GCC switches, this
  81      loop executes at most twice.  */
  82   do
  83     {
  84       const struct cl_option *opt = &cl_options[mn];
  85
  86       /* Is the input either an exact match or a prefix that takes a
  87          joined argument?  */
  88       if (!strncmp (input, opt->opt_text + 1, opt->opt_len)
  89           && (input[opt->opt_len] == '\0' || (opt->flags & CL_JOINED)))
  90         {
  91           /* If language is OK, return it.  */
  92           if (opt->flags & lang_mask)
  93             return mn;
  94
  95           /* If we haven't remembered a prior match, remember this
  96              one.  Any prior match is necessarily better.  */
  97           if (match_wrong_lang == cl_options_count)
  98             match_wrong_lang = mn;
  99         }
 100
 101       /* Try the next possibility.  This is cl_options_count if there
 102          are no more.  */
 103       mn = opt->back_chain;
 104     }
 105   while (mn != cl_options_count);
 106
 107   /* Return the best wrong match, or cl_options_count if none.  */
 108   return match_wrong_lang;
 109 }
 110
 111 /* Return true if NEXT_OPT_IDX cancels OPT_IDX.  Return false if the
 112    next one is the same as ORIG_NEXT_OPT_IDX.  */
 113
 114 static bool
 115 cancel_option (int opt_idx, int next_opt_idx, int orig_next_opt_idx)
 116 {
 117   /* An option can be canceled by the same option or an option with
 118      Negative.  */
 119   if (cl_options [next_opt_idx].neg_index == opt_idx)
 120     return true;
 121
 122   if (cl_options [next_opt_idx].neg_index != orig_next_opt_idx)
 123     return cancel_option (opt_idx, cl_options [next_opt_idx].neg_index,
 124                           orig_next_opt_idx);
 125
 126   return false;
 127 }
 128
 129 /* Filter out options canceled by the ones after them.  */
 130
 131 void
 132 prune_options (int *argcp, char ***argvp)
 133 {
 134   int argc = *argcp;
 135   int *options = xmalloc (argc * sizeof (*options));
 136   char **argv = xmalloc (argc * sizeof (char *));
 137   int i, arg_count, need_prune = 0;
 138   const struct cl_option *option;
 139   size_t opt_index;
 140
 141   /* Scan all arguments.  */
 142   for (i = 1; i < argc; i++)
 143     {
 144       int value = 1;
 145       const char *opt = (*argvp) [i];
 146
 147       opt_index = find_opt (opt + 1, -1);
 148       if (opt_index == cl_options_count
 149           && (opt[1] == 'W' || opt[1] == 'f' || opt[1] == 'm')
 150           && opt[2] == 'n' && opt[3] == 'o' && opt[4] == '-')
 151         {
 152           char *dup;
 153
 154           /* Drop the "no-" from negative switches.  */
 155           size_t len = strlen (opt) - 3;
 156
 157           dup = XNEWVEC (char, len + 1);
 158           dup[0] = '-';
 159           dup[1] = opt[1];
 160           memcpy (dup + 2, opt + 5, len - 2 + 1);
 161           opt = dup;
 162           value = 0;
 163           opt_index = find_opt (opt + 1, -1);
 164           free (dup);
 165         }
 166
 167       if (opt_index == cl_options_count)
 168         {
 169 cont:
 170           options [i] = 0;
 171           continue;
 172         }
 173
 174       option = &cl_options[opt_index];
 175       if (option->neg_index < 0)
 176         goto cont;
 177
 178       /* Skip joined switches.  */
 179       if ((option->flags & CL_JOINED))
 180         goto cont;
 181
 182       /* Reject negative form of switches that don't take negatives as
 183          unrecognized.  */
 184       if (!value && (option->flags & CL_REJECT_NEGATIVE))
 185         goto cont;
 186
 187       options [i] = (int) opt_index;
 188       need_prune |= options [i];
 189     }
 190
 191   if (!need_prune)
 192     goto done;
 193
 194   /* Remove arguments which are negated by others after them.  */
 195   argv [0] = (*argvp) [0];
 196   arg_count = 1;
 197   for (i = 1; i < argc; i++)
 198     {
 199       int j, opt_idx;
 200
 201       opt_idx = options [i];
 202       if (opt_idx)
 203         {
 204           int next_opt_idx;
 205           for (j = i + 1; j < argc; j++)
 206             {
 207               next_opt_idx = options [j];
 208               if (next_opt_idx
 209                   && cancel_option (opt_idx, next_opt_idx,
 210                                     next_opt_idx))
 211                 break;
 212             }
 213         }
 214       else
 215         goto keep;
 216
 217       if (j == argc)
 218         {
 219 keep:
 220           argv [arg_count] = (*argvp) [i];
 221           arg_count++;
 222         }
 223     }
 224
 225   if (arg_count != argc)
 226     {
 227       *argcp = arg_count;
 228       *argvp = argv;
 229     }
 230   else
 231     {
 232 done:
 233       free (argv);
 234     }
 235
 236   free (options);
 237 }