gcc/opt-problem.cc

   1 /* Rich optional information on why an optimization wasn't possible.
   2    Copyright (C) 2018-2024 Free Software Foundation, Inc.
   3    Contributed by David Malcolm <dmalcolm@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "backend.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "pretty-print.h"
  28 #include "opt-problem.h"
  29 #include "dump-context.h"
  30 #include "tree-pass.h"
  31 #include "selftest.h"
  32
  33 /* opt_problem's ctor.
  34
  35    Use FMT and AP to emit a message to the "immediate" dump destinations
  36    as if via:
  37      dump_printf_loc (MSG_MISSED_OPTIMIZATION, loc, ...)
  38
  39    The optinfo_item instances are not emitted yet.  Instead, they
  40    are retained internally so that the message can be replayed and
  41    emitted when this problem is handled, higher up the call stack.  */
  42
  43 opt_problem::opt_problem (const dump_location_t &loc,
  44                           const char *fmt, va_list *ap)
  45 : m_optinfo (loc, OPTINFO_KIND_FAILURE, current_pass)
  46 {
  47   /* We shouldn't be bothering to construct these objects if
  48      dumping isn't enabled.  */
  49   gcc_assert (dump_enabled_p ());
  50
  51   /* Update the singleton.  */
  52   delete s_the_problem;
  53   s_the_problem = this;
  54
  55   /* Print the location to the "immediate" dump destinations.  */
  56   dump_context &dc = dump_context::get ();
  57   dc.dump_loc (MSG_MISSED_OPTIMIZATION, loc.get_user_location ());
  58
  59   /* Print the formatted string to this opt_problem's optinfo, dumping
  60      the items to the "immediate" dump destinations, and storing items
  61      for later retrieval.  */
  62   {
  63     dump_pretty_printer pp (&dump_context::get (), MSG_MISSED_OPTIMIZATION);
  64
  65     text_info text (fmt, /* No i18n is performed.  */
  66                     ap, errno);
  67
  68     /* Phases 1 and 2, using pp_format.  */
  69     pp_format (&pp, &text);
  70
  71     /* Phase 3: dump the items to the "immediate" dump destinations,
  72        and storing them into m_optinfo for later retrieval.  */
  73     pp.emit_items (&m_optinfo);
  74   }
  75 }
  76
  77 /* Emit this problem and delete it, clearing the current opt_problem.  */
  78
  79 void
  80 opt_problem::emit_and_clear ()
  81 {
  82   gcc_assert (this == s_the_problem);
  83
  84   m_optinfo.emit_for_opt_problem ();
  85
  86   delete this;
  87   s_the_problem = NULL;
  88 }
  89
  90 /* The singleton opt_problem *.  */
  91
  92 opt_problem *opt_problem::s_the_problem;
  93
  94 #if CHECKING_P
  95
  96 namespace selftest {
  97
  98 static opt_result
  99 function_that_succeeds ()
 100 {
 101   return opt_result::success ();
 102 }
 103
 104 /* Verify that opt_result::success works.  */
 105
 106 static void
 107 test_opt_result_success ()
 108 {
 109   /* Run all tests twice, with and then without dumping enabled.  */
 110   for (int i = 0 ; i < 2; i++)
 111     {
 112       bool with_dumping = (i == 0);
 113
 114       temp_dump_context tmp (with_dumping, with_dumping,
 115                              MSG_ALL_KINDS | MSG_ALL_PRIORITIES);
 116
 117       if (with_dumping)
 118         gcc_assert (dump_enabled_p ());
 119       else
 120         gcc_assert (!dump_enabled_p ());
 121
 122       opt_result res = function_that_succeeds ();
 123
 124       /* Verify that "success" can be used as a "true" boolean.  */
 125       ASSERT_TRUE (res);
 126
 127       /* Verify the underlying opt_wrapper<bool>.  */
 128       ASSERT_TRUE (res.get_result ());
 129       ASSERT_EQ (res.get_problem (), NULL);
 130
 131       /* Nothing should have been dumped.  */
 132       ASSERT_DUMPED_TEXT_EQ (tmp, "");
 133       optinfo *info = tmp.get_pending_optinfo ();
 134       ASSERT_EQ (info, NULL);
 135     }
 136 }
 137
 138 /* Example of a function that fails, with a non-trivial
 139    pre-canned error message.  */
 140
 141 static opt_result
 142 function_that_fails (const greturn *stmt)
 143 {
 144   gcc_assert (stmt);
 145   gcc_assert (gimple_return_retval (stmt));
 146
 147   AUTO_DUMP_SCOPE ("function_that_fails", stmt);
 148
 149   return opt_result::failure_at (stmt,
 150                                  "can't handle return type: %T for stmt: %G",
 151                                  TREE_TYPE (gimple_return_retval (stmt)),
 152                                  static_cast <const gimple *> (stmt));
 153 }
 154
 155 /* Example of a function that indirectly fails.  */
 156
 157 static opt_result
 158 function_that_indirectly_fails (const greturn *stmt)
 159 {
 160   AUTO_DUMP_SCOPE ("function_that_indirectly_fails", stmt);
 161
 162   opt_result res = function_that_fails (stmt);
 163   if (!res)
 164     return res;
 165   return opt_result::success ();
 166 }
 167
 168 /* Verify that opt_result::failure_at works.
 169    Simulate a failure handling a stmt at one location whilst considering
 170    an optimization that's notionally at another location (as a microcosm
 171    of e.g. a problematic statement within a loop that prevents loop
 172    vectorization).  */
 173
 174 static void
 175 test_opt_result_failure_at (const line_table_case &case_)
 176 {
 177   /* Generate a location_t for testing.  */
 178   line_table_test ltt (case_);
 179   const line_map_ordinary *ord_map
 180     = linemap_check_ordinary (linemap_add (line_table, LC_ENTER, false,
 181                                            "test.c", 0));
 182   linemap_line_start (line_table, 5, 100);
 183
 184   /* A test location: "test.c:5:10".  */
 185   const location_t line_5 = linemap_position_for_column (line_table, 10);
 186
 187   /* Another test location: "test.c:6:12".  */
 188   const location_t line_6
 189     = linemap_position_for_line_and_column (line_table, ord_map, 6, 12);
 190
 191   if (line_6 > LINE_MAP_MAX_LOCATION_WITH_COLS)
 192     return;
 193
 194   /* Generate statements using "line_5" and "line_6" for testing.  */
 195   greturn *stmt_at_5 = gimple_build_return (integer_one_node);
 196   gimple_set_location (stmt_at_5, line_5);
 197
 198   greturn *stmt_at_6 = gimple_build_return (integer_zero_node);
 199   gimple_set_location (stmt_at_6, line_6);
 200
 201   /* Run with and then without dumping enabled.  */
 202   for (int i = 0; i < 2; i++)
 203     {
 204       bool with_dumping = (i == 0);
 205
 206       /* Run with all 4 combinations of
 207          with and without MSG_PRIORITY_INTERNALS and
 208          with and without MSG_PRIORITY_REEMITTED.  */
 209       for (int j = 0; j < 4; j++)
 210         {
 211           dump_flags_t filter = MSG_ALL_KINDS | MSG_PRIORITY_USER_FACING;
 212           if (j / 2)
 213             filter |= MSG_PRIORITY_INTERNALS;
 214           if (j % 2)
 215             filter |= MSG_PRIORITY_REEMITTED;
 216
 217           temp_dump_context tmp (with_dumping, with_dumping, filter);
 218
 219           if (with_dumping)
 220             gcc_assert (dump_enabled_p ());
 221           else
 222             gcc_assert (!dump_enabled_p ());
 223
 224           /* Simulate attempting to optimize "stmt_at_6".  */
 225           opt_result res = function_that_indirectly_fails (stmt_at_6);
 226
 227           /* Verify that "failure" can be used as a "false" boolean.  */
 228           ASSERT_FALSE (res);
 229
 230           /* Verify the underlying opt_wrapper<bool>.  */
 231           ASSERT_FALSE (res.get_result ());
 232           opt_problem *problem = res.get_problem ();
 233
 234           if (with_dumping)
 235             {
 236               ASSERT_NE (problem, NULL);
 237               ASSERT_EQ (problem->get_dump_location ().get_location_t (),
 238                          line_6);
 239 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)
 240               /* Verify that the problem captures the implementation location
 241                  it was emitted from.  */
 242               const dump_impl_location_t &impl_location
 243                 = problem->get_dump_location ().get_impl_location ();
 244               ASSERT_STR_CONTAINS (impl_location.m_function,
 245                                    "function_that_fails");
 246 #endif
 247
 248               /* Verify that the underlying dump items are retained in the
 249                  opt_problem.  */
 250               const optinfo &info = problem->get_optinfo ();
 251               ASSERT_EQ (info.get_dump_location ().get_location_t (), line_6);
 252               ASSERT_EQ (info.num_items (), 4);
 253               ASSERT_IS_TEXT (info.get_item (0), "can't handle return type: ");
 254               ASSERT_IS_TREE (info.get_item (1), UNKNOWN_LOCATION, "int");
 255               ASSERT_IS_TEXT (info.get_item (2), " for stmt: ");
 256               ASSERT_IS_GIMPLE (info.get_item (3), line_6, "return 0;\n");
 257
 258               /* ...but not in the dump_context's pending_optinfo.  */
 259               ASSERT_EQ (tmp.get_pending_optinfo (), NULL);
 260
 261               /* Simulate emitting a high-level summary message, followed
 262                  by the problem.  */
 263               dump_printf_loc (MSG_MISSED_OPTIMIZATION, stmt_at_5,
 264                                "can't optimize loop\n");
 265               problem->emit_and_clear ();
 266               ASSERT_EQ (res.get_problem (), NULL);
 267
 268               /* Verify that the error message was dumped (when the failure
 269                  occurred).  We can't use a switch here as not all of the
 270                  values are const expressions (using C++98).  */
 271               dump_flags_t effective_filter
 272                 = filter & (MSG_PRIORITY_INTERNALS | MSG_PRIORITY_REEMITTED);
 273               if (effective_filter
 274                   == (MSG_PRIORITY_INTERNALS | MSG_PRIORITY_REEMITTED))
 275                 /* The -fopt-info-internals case.  */
 276                 ASSERT_DUMPED_TEXT_EQ
 277                   (tmp,
 278                    "test.c:6:12: note:  === function_that_indirectly_fails"
 279                    " ===\n"
 280                    "test.c:6:12: note:   === function_that_fails ===\n"
 281                    "test.c:6:12: missed:   can't handle return type: int"
 282                    " for stmt: return 0;\n"
 283                    "test.c:5:10: missed: can't optimize loop\n"
 284                    "test.c:6:12: missed: can't handle return type: int"
 285                    " for stmt: return 0;\n");
 286               else if (effective_filter == MSG_PRIORITY_INTERNALS)
 287                 /* The default for dump files.  */
 288                 ASSERT_DUMPED_TEXT_EQ
 289                   (tmp,
 290                    "test.c:6:12: note:  === function_that_indirectly_fails"
 291                    " ===\n"
 292                    "test.c:6:12: note:   === function_that_fails ===\n"
 293                    "test.c:6:12: missed:   can't handle return type: int"
 294                      " for stmt: return 0;\n"
 295                    "test.c:5:10: missed: can't optimize loop\n");
 296               else if (effective_filter == MSG_PRIORITY_REEMITTED)
 297                 /* The default when -fopt-info is enabled.  */
 298                 ASSERT_DUMPED_TEXT_EQ
 299                   (tmp,
 300                    "test.c:5:10: missed: can't optimize loop\n"
 301                    "test.c:6:12: missed: can't handle return type: int"
 302                    " for stmt: return 0;\n");
 303               else
 304                 {
 305                   gcc_assert (effective_filter == 0);
 306                   ASSERT_DUMPED_TEXT_EQ
 307                     (tmp,
 308                      "test.c:5:10: missed: can't optimize loop\n");
 309                 }
 310             }
 311           else
 312             {
 313               /* If dumping was disabled, then no problem should have been
 314                  created, and nothing should have been dumped.  */
 315               ASSERT_EQ (problem, NULL);
 316               ASSERT_DUMPED_TEXT_EQ (tmp, "");
 317             }
 318         }
 319     }
 320 }
 321
 322 /* Run all of the selftests within this file.  */
 323
 324 void
 325 c_opt_problem_cc_tests ()
 326 {
 327   test_opt_result_success ();
 328   for_each_line_table_case (test_opt_result_failure_at);
 329 }
 330
 331 } // namespace selftest
 332
 333 #endif /* CHECKING_P */