gcc/opt-problem.cc

   1 /* Rich optional information on why an optimization wasn't possible.
   2    Copyright (C) 2018-2023 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;
  66     text.err_no = errno;
  67     text.args_ptr = ap;
  68     text.format_spec = fmt; /* No i18n is performed.  */
  69
  70     /* Phases 1 and 2, using pp_format.  */
  71     pp_format (&pp, &text);
  72
  73     /* Phase 3: dump the items to the "immediate" dump destinations,
  74        and storing them into m_optinfo for later retrieval.  */
  75     pp.emit_items (&m_optinfo);
  76   }
  77 }
  78
  79 /* Emit this problem and delete it, clearing the current opt_problem.  */
  80
  81 void
  82 opt_problem::emit_and_clear ()
  83 {
  84   gcc_assert (this == s_the_problem);
  85
  86   m_optinfo.emit_for_opt_problem ();
  87
  88   delete this;
  89   s_the_problem = NULL;
  90 }
  91
  92 /* The singleton opt_problem *.  */
  93
  94 opt_problem *opt_problem::s_the_problem;
  95
  96 #if CHECKING_P
  97
  98 namespace selftest {
  99
 100 static opt_result
 101 function_that_succeeds ()
 102 {
 103   return opt_result::success ();
 104 }
 105
 106 /* Verify that opt_result::success works.  */
 107
 108 static void
 109 test_opt_result_success ()
 110 {
 111   /* Run all tests twice, with and then without dumping enabled.  */
 112   for (int i = 0 ; i < 2; i++)
 113     {
 114       bool with_dumping = (i == 0);
 115
 116       temp_dump_context tmp (with_dumping, with_dumping,
 117                              MSG_ALL_KINDS | MSG_ALL_PRIORITIES);
 118
 119       if (with_dumping)
 120         gcc_assert (dump_enabled_p ());
 121       else
 122         gcc_assert (!dump_enabled_p ());
 123
 124       opt_result res = function_that_succeeds ();
 125
 126       /* Verify that "success" can be used as a "true" boolean.  */
 127       ASSERT_TRUE (res);
 128
 129       /* Verify the underlying opt_wrapper<bool>.  */
 130       ASSERT_TRUE (res.get_result ());
 131       ASSERT_EQ (res.get_problem (), NULL);
 132
 133       /* Nothing should have been dumped.  */
 134       ASSERT_DUMPED_TEXT_EQ (tmp, "");
 135       optinfo *info = tmp.get_pending_optinfo ();
 136       ASSERT_EQ (info, NULL);
 137     }
 138 }
 139
 140 /* Example of a function that fails, with a non-trivial
 141    pre-canned error message.  */
 142
 143 static opt_result
 144 function_that_fails (const greturn *stmt)
 145 {
 146   gcc_assert (stmt);
 147   gcc_assert (gimple_return_retval (stmt));
 148
 149   AUTO_DUMP_SCOPE ("function_that_fails", stmt);
 150
 151   return opt_result::failure_at (stmt,
 152                                  "can't handle return type: %T for stmt: %G",
 153                                  TREE_TYPE (gimple_return_retval (stmt)),
 154                                  static_cast <const gimple *> (stmt));
 155 }
 156
 157 /* Example of a function that indirectly fails.  */
 158
 159 static opt_result
 160 function_that_indirectly_fails (const greturn *stmt)
 161 {
 162   AUTO_DUMP_SCOPE ("function_that_indirectly_fails", stmt);
 163
 164   opt_result res = function_that_fails (stmt);
 165   if (!res)
 166     return res;
 167   return opt_result::success ();
 168 }
 169
 170 /* Verify that opt_result::failure_at works.
 171    Simulate a failure handling a stmt at one location whilst considering
 172    an optimization that's notionally at another location (as a microcosm
 173    of e.g. a problematic statement within a loop that prevents loop
 174    vectorization).  */
 175
 176 static void
 177 test_opt_result_failure_at (const line_table_case &case_)
 178 {
 179   /* Generate a location_t for testing.  */
 180   line_table_test ltt (case_);
 181   const line_map_ordinary *ord_map
 182     = linemap_check_ordinary (linemap_add (line_table, LC_ENTER, false,
 183                                            "test.c", 0));
 184   linemap_line_start (line_table, 5, 100);
 185
 186   /* A test location: "test.c:5:10".  */
 187   const location_t line_5 = linemap_position_for_column (line_table, 10);
 188
 189   /* Another test location: "test.c:6:12".  */
 190   const location_t line_6
 191     = linemap_position_for_line_and_column (line_table, ord_map, 6, 12);
 192
 193   if (line_6 > LINE_MAP_MAX_LOCATION_WITH_COLS)
 194     return;
 195
 196   /* Generate statements using "line_5" and "line_6" for testing.  */
 197   greturn *stmt_at_5 = gimple_build_return (integer_one_node);
 198   gimple_set_location (stmt_at_5, line_5);
 199
 200   greturn *stmt_at_6 = gimple_build_return (integer_zero_node);
 201   gimple_set_location (stmt_at_6, line_6);
 202
 203   /* Run with and then without dumping enabled.  */
 204   for (int i = 0; i < 2; i++)
 205     {
 206       bool with_dumping = (i == 0);
 207
 208       /* Run with all 4 combinations of
 209          with and without MSG_PRIORITY_INTERNALS and
 210          with and without MSG_PRIORITY_REEMITTED.  */
 211       for (int j = 0; j < 4; j++)
 212         {
 213           dump_flags_t filter = MSG_ALL_KINDS | MSG_PRIORITY_USER_FACING;
 214           if (j / 2)
 215             filter |= MSG_PRIORITY_INTERNALS;
 216           if (j % 2)
 217             filter |= MSG_PRIORITY_REEMITTED;
 218
 219           temp_dump_context tmp (with_dumping, with_dumping, filter);
 220
 221           if (with_dumping)
 222             gcc_assert (dump_enabled_p ());
 223           else
 224             gcc_assert (!dump_enabled_p ());
 225
 226           /* Simulate attempting to optimize "stmt_at_6".  */
 227           opt_result res = function_that_indirectly_fails (stmt_at_6);
 228
 229           /* Verify that "failure" can be used as a "false" boolean.  */
 230           ASSERT_FALSE (res);
 231
 232           /* Verify the underlying opt_wrapper<bool>.  */
 233           ASSERT_FALSE (res.get_result ());
 234           opt_problem *problem = res.get_problem ();
 235
 236           if (with_dumping)
 237             {
 238               ASSERT_NE (problem, NULL);
 239               ASSERT_EQ (problem->get_dump_location ().get_location_t (),
 240                          line_6);
 241 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)
 242               /* Verify that the problem captures the implementation location
 243                  it was emitted from.  */
 244               const dump_impl_location_t &impl_location
 245                 = problem->get_dump_location ().get_impl_location ();
 246               ASSERT_STR_CONTAINS (impl_location.m_function,
 247                                    "function_that_fails");
 248 #endif
 249
 250               /* Verify that the underlying dump items are retained in the
 251                  opt_problem.  */
 252               const optinfo &info = problem->get_optinfo ();
 253               ASSERT_EQ (info.get_dump_location ().get_location_t (), line_6);
 254               ASSERT_EQ (info.num_items (), 4);
 255               ASSERT_IS_TEXT (info.get_item (0), "can't handle return type: ");
 256               ASSERT_IS_TREE (info.get_item (1), UNKNOWN_LOCATION, "int");
 257               ASSERT_IS_TEXT (info.get_item (2), " for stmt: ");
 258               ASSERT_IS_GIMPLE (info.get_item (3), line_6, "return 0;\n");
 259
 260               /* ...but not in the dump_context's pending_optinfo.  */
 261               ASSERT_EQ (tmp.get_pending_optinfo (), NULL);
 262
 263               /* Simulate emitting a high-level summary message, followed
 264                  by the problem.  */
 265               dump_printf_loc (MSG_MISSED_OPTIMIZATION, stmt_at_5,
 266                                "can't optimize loop\n");
 267               problem->emit_and_clear ();
 268               ASSERT_EQ (res.get_problem (), NULL);
 269
 270               /* Verify that the error message was dumped (when the failure
 271                  occurred).  We can't use a switch here as not all of the
 272                  values are const expressions (using C++98).  */
 273               dump_flags_t effective_filter
 274                 = filter & (MSG_PRIORITY_INTERNALS | MSG_PRIORITY_REEMITTED);
 275               if (effective_filter
 276                   == (MSG_PRIORITY_INTERNALS | MSG_PRIORITY_REEMITTED))
 277                 /* The -fopt-info-internals case.  */
 278                 ASSERT_DUMPED_TEXT_EQ
 279                   (tmp,
 280                    "test.c:6:12: note:  === function_that_indirectly_fails"
 281                    " ===\n"
 282                    "test.c:6:12: note:   === function_that_fails ===\n"
 283                    "test.c:6:12: missed:   can't handle return type: int"
 284                    " for stmt: return 0;\n"
 285                    "test.c:5:10: missed: can't optimize loop\n"
 286                    "test.c:6:12: missed: can't handle return type: int"
 287                    " for stmt: return 0;\n");
 288               else if (effective_filter == MSG_PRIORITY_INTERNALS)
 289                 /* The default for dump files.  */
 290                 ASSERT_DUMPED_TEXT_EQ
 291                   (tmp,
 292                    "test.c:6:12: note:  === function_that_indirectly_fails"
 293                    " ===\n"
 294                    "test.c:6:12: note:   === function_that_fails ===\n"
 295                    "test.c:6:12: missed:   can't handle return type: int"
 296                      " for stmt: return 0;\n"
 297                    "test.c:5:10: missed: can't optimize loop\n");
 298               else if (effective_filter == MSG_PRIORITY_REEMITTED)
 299                 /* The default when -fopt-info is enabled.  */
 300                 ASSERT_DUMPED_TEXT_EQ
 301                   (tmp,
 302                    "test.c:5:10: missed: can't optimize loop\n"
 303                    "test.c:6:12: missed: can't handle return type: int"
 304                    " for stmt: return 0;\n");
 305               else
 306                 {
 307                   gcc_assert (effective_filter == 0);
 308                   ASSERT_DUMPED_TEXT_EQ
 309                     (tmp,
 310                      "test.c:5:10: missed: can't optimize loop\n");
 311                 }
 312             }
 313           else
 314             {
 315               /* If dumping was disabled, then no problem should have been
 316                  created, and nothing should have been dumped.  */
 317               ASSERT_EQ (problem, NULL);
 318               ASSERT_DUMPED_TEXT_EQ (tmp, "");
 319             }
 320         }
 321     }
 322 }
 323
 324 /* Run all of the selftests within this file.  */
 325
 326 void
 327 c_opt_problem_cc_tests ()
 328 {
 329   test_opt_result_success ();
 330   for_each_line_table_case (test_opt_result_failure_at);
 331 }
 332
 333 } // namespace selftest
 334
 335 #endif /* CHECKING_P */