gcc/java/except.c

   1 /* Handle exceptions for GNU compiler for the Java(TM) language.
   2    Copyright (C) 1997-2014 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
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.
  19
  20 Java and all Java-based marks are trademarks or registered trademarks
  21 of Sun Microsystems, Inc. in the United States and other countries.
  22 The Free Software Foundation is independent of Sun Microsystems, Inc.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "coretypes.h"
  27 #include "tm.h"
  28 #include "tree.h"
  29 #include "stringpool.h"
  30 #include "stor-layout.h"
  31 #include "java-tree.h"
  32 #include "javaop.h"
  33 #include "java-opcodes.h"
  34 #include "jcf.h"
  35 #include "java-except.h"
  36 #include "diagnostic-core.h"
  37 #include "toplev.h"
  38 #include "tree-iterator.h"
  39
  40
  41 static void expand_start_java_handler (struct eh_range *);
  42 static struct eh_range *find_handler_in_range (int, struct eh_range *,
  43                                                struct eh_range *);
  44 static void check_start_handlers (struct eh_range *, int);
  45 static void free_eh_ranges (struct eh_range *range);
  46
  47 struct eh_range *current_method_handlers;
  48
  49 struct eh_range *current_try_block = NULL;
  50
  51 /* These variables are used to speed up find_handler. */
  52
  53 static int cache_range_start, cache_range_end;
  54 static struct eh_range *cache_range;
  55 static struct eh_range *cache_next_child;
  56
  57 /* A dummy range that represents the entire method. */
  58
  59 struct eh_range whole_range;
  60
  61 /* Check the invariants of the structure we're using to contain
  62    exception regions.  Either returns true or fails an assertion
  63    check.  */
  64
  65 bool
  66 sanity_check_exception_range (struct eh_range *range)
  67 {
  68   struct eh_range *ptr = range->first_child;
  69   for (; ptr; ptr = ptr->next_sibling)
  70     {
  71       gcc_assert (ptr->outer == range
  72                   && ptr->end_pc > ptr->start_pc);
  73       if (ptr->next_sibling)
  74         gcc_assert (ptr->next_sibling->start_pc >= ptr->end_pc);
  75       gcc_assert (ptr->start_pc >= ptr->outer->start_pc
  76                   && ptr->end_pc <=  ptr->outer->end_pc);
  77       (void) sanity_check_exception_range (ptr);
  78     }
  79   return true;
  80 }
  81
  82 #if defined(DEBUG_JAVA_BINDING_LEVELS)
  83 extern int is_class_level;
  84 extern int current_pc;
  85 extern int binding_depth;
  86 extern void indent (void);
  87 static void
  88 print_ranges (struct eh_range *range)
  89 {
  90   if (! range)
  91     return;
  92
  93   struct eh_range *child = range->first_child;
  94
  95   indent ();
  96   fprintf (stderr, "handler pc %d --> %d ", range->start_pc, range->end_pc);
  97
  98   tree handler = range->handlers;
  99   for ( ; handler != NULL_TREE; handler = TREE_CHAIN (handler))
 100     {
 101       tree type = TREE_PURPOSE (handler);
 102       if (type == NULL)
 103         type = throwable_type_node;
 104       fprintf (stderr, " type=%s ", IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type))));
 105     }
 106   fprintf (stderr, "\n");
 107
 108   int saved = binding_depth;
 109   binding_depth++;
 110   print_ranges (child);
 111   binding_depth = saved;
 112
 113   print_ranges (range->next_sibling);
 114 }
 115 #endif
 116
 117 /* Search for the most specific eh_range containing PC.
 118    Assume PC is within RANGE.
 119    CHILD is a list of children of RANGE such that any
 120    previous children have end_pc values that are too low. */
 121
 122 static struct eh_range *
 123 find_handler_in_range (int pc, struct eh_range *range, struct eh_range *child)
 124 {
 125   for (; child != NULL;  child = child->next_sibling)
 126     {
 127       if (pc < child->start_pc)
 128         break;
 129       if (pc < child->end_pc)
 130         return find_handler_in_range (pc, child, child->first_child);
 131     }
 132   cache_range = range;
 133   cache_range_start = pc;
 134   cache_next_child = child;
 135   cache_range_end = child == NULL ? range->end_pc : child->start_pc;
 136   return range;
 137 }
 138
 139 /* Find the inner-most handler that contains PC. */
 140
 141 struct eh_range *
 142 find_handler (int pc)
 143 {
 144   struct eh_range *h;
 145   if (pc >= cache_range_start)
 146     {
 147       h = cache_range;
 148       if (pc < cache_range_end)
 149         return h;
 150       while (pc >= h->end_pc)
 151         {
 152           cache_next_child = h->next_sibling;
 153           h = h->outer;
 154         }
 155     }
 156   else
 157     {
 158       h = &whole_range;
 159       cache_next_child = h->first_child;
 160     }
 161   return find_handler_in_range (pc, h, cache_next_child);
 162 }
 163
 164 static void
 165 free_eh_ranges (struct eh_range *range)
 166 {
 167   while (range)
 168     {
 169       struct eh_range *next = range->next_sibling;
 170       free_eh_ranges (range->first_child);
 171       if (range != &whole_range)
 172         free (range);
 173       range = next;
 174     }
 175 }
 176
 177 /* Called to re-initialize the exception machinery for a new method. */
 178
 179 void
 180 method_init_exceptions (void)
 181 {
 182   free_eh_ranges (&whole_range);
 183   whole_range.start_pc = 0;
 184   whole_range.end_pc = DECL_CODE_LENGTH (current_function_decl) + 1;
 185   whole_range.outer = NULL;
 186   whole_range.first_child = NULL;
 187   whole_range.next_sibling = NULL;
 188   cache_range_start = 0xFFFFFF;
 189 }
 190
 191 /* Split an exception range into two at PC.  The sub-ranges that
 192    belong to the range are split and distributed between the two new
 193    ranges.  */
 194
 195 static void
 196 split_range (struct eh_range *range, int pc)
 197 {
 198   struct eh_range *ptr;
 199   struct eh_range **first_child, **second_child;
 200   struct eh_range *h;
 201
 202   /* First, split all the sub-ranges.  */
 203   for (ptr = range->first_child; ptr; ptr = ptr->next_sibling)
 204     {
 205       if (pc > ptr->start_pc
 206           && pc < ptr->end_pc)
 207         {
 208           split_range (ptr, pc);
 209         }
 210     }
 211
 212   /* Create a new range.  */
 213   h = XNEW (struct eh_range);
 214
 215   h->start_pc = pc;
 216   h->end_pc = range->end_pc;
 217   h->next_sibling = range->next_sibling;
 218   range->next_sibling = h;
 219   range->end_pc = pc;
 220   h->handlers = build_tree_list (TREE_PURPOSE (range->handlers),
 221                                  TREE_VALUE (range->handlers));
 222   h->next_sibling = NULL;
 223   h->expanded = 0;
 224   h->stmt = NULL;
 225   h->outer = range->outer;
 226   h->first_child = NULL;
 227
 228   ptr = range->first_child;
 229   first_child = &range->first_child;
 230   second_child = &h->first_child;
 231
 232   /* Distribute the sub-ranges between the two new ranges.  */
 233   for (ptr = range->first_child; ptr; ptr = ptr->next_sibling)
 234     {
 235       if (ptr->start_pc < pc)
 236         {
 237           *first_child = ptr;
 238           ptr->outer = range;
 239           first_child = &ptr->next_sibling;
 240         }
 241       else
 242         {
 243           *second_child = ptr;
 244           ptr->outer = h;
 245           second_child = &ptr->next_sibling;
 246         }
 247     }
 248   *first_child = NULL;
 249   *second_child = NULL;
 250 }
 251
 252
 253 /* Add an exception range.
 254
 255    There are some missed optimization opportunities here.  For
 256    example, some bytecode obfuscators generate seemingly
 257    nonoverlapping exception ranges which, when coalesced, do in fact
 258    nest correctly.  We could merge these, but we'd have to fix up all
 259    the enclosed regions first and perhaps create a new range anyway if
 260    it overlapped existing ranges.
 261
 262    Also, we don't attempt to detect the case where two previously
 263    added disjoint ranges could be coalesced by a new range.  */
 264
 265 void
 266 add_handler (int start_pc, int end_pc, tree handler, tree type)
 267 {
 268   struct eh_range *ptr, *h;
 269   struct eh_range **first_child, **prev;
 270
 271   /* First, split all the existing ranges that we need to enclose.  */
 272   for (ptr = whole_range.first_child; ptr; ptr = ptr->next_sibling)
 273     {
 274       if (start_pc > ptr->start_pc
 275           && start_pc < ptr->end_pc)
 276         {
 277           split_range (ptr, start_pc);
 278         }
 279
 280       if (end_pc > ptr->start_pc
 281           && end_pc < ptr->end_pc)
 282         {
 283           split_range (ptr, end_pc);
 284         }
 285
 286       if (ptr->start_pc >= end_pc)
 287         break;
 288     }
 289
 290   /* Create the new range.  */
 291   h = XNEW (struct eh_range);
 292   first_child = &h->first_child;
 293
 294   h->start_pc = start_pc;
 295   h->end_pc = end_pc;
 296   h->first_child = NULL;
 297   h->outer = NULL_EH_RANGE;
 298   h->handlers = build_tree_list (type, handler);
 299   h->next_sibling = NULL;
 300   h->expanded = 0;
 301   h->stmt = NULL;
 302
 303   /* Find every range at the top level that will be a sub-range of the
 304      range we're inserting and make it so.  */
 305   {
 306     struct eh_range **prev = &whole_range.first_child;
 307     for (ptr = *prev; ptr;)
 308       {
 309         struct eh_range *next = ptr->next_sibling;
 310
 311         if (ptr->start_pc >= end_pc)
 312           break;
 313
 314         if (ptr->start_pc < start_pc)
 315           {
 316             prev = &ptr->next_sibling;
 317           }
 318         else if (ptr->start_pc >= start_pc
 319                  && ptr->start_pc < end_pc)
 320           {
 321             *prev = next;
 322             *first_child = ptr;
 323             first_child = &ptr->next_sibling;
 324             ptr->outer = h;
 325             ptr->next_sibling = NULL;
 326           }
 327
 328         ptr = next;
 329       }
 330   }
 331
 332   /* Find the right place to insert the new range.  */
 333   prev = &whole_range.first_child;
 334   for (ptr = *prev; ptr; prev = &ptr->next_sibling, ptr = ptr->next_sibling)
 335     {
 336       gcc_assert (ptr->outer == NULL_EH_RANGE);
 337       if (ptr->start_pc >= start_pc)
 338         break;
 339     }
 340
 341   /* And insert it there.  */
 342   *prev = h;
 343   if (ptr)
 344     {
 345       h->next_sibling = ptr;
 346       h->outer = ptr->outer;
 347     }
 348 }
 349
 350
 351 /* if there are any handlers for this range, issue start of region */
 352 static void
 353 expand_start_java_handler (struct eh_range *range)
 354 {
 355 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 356   indent ();
 357   fprintf (stderr, "expand start handler pc %d --> %d\n",
 358            current_pc, range->end_pc);
 359 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 360   pushlevel (0);
 361   register_exception_range (range,  range->start_pc, range->end_pc);
 362   range->expanded = 1;
 363 }
 364
 365 tree
 366 prepare_eh_table_type (tree type)
 367 {
 368   tree exp;
 369   tree *slot;
 370   const char *name;
 371   char *buf;
 372   tree decl;
 373   tree utf8_ref;
 374
 375   /* The "type" (match_info) in a (Java) exception table is a pointer to:
 376    * a) NULL - meaning match any type in a try-finally.
 377    * b) a pointer to a pointer to a class.
 378    * c) a pointer to a pointer to a utf8_ref.  The pointer is
 379    * rewritten to point to the appropriate class.  */
 380
 381   if (type == NULL_TREE)
 382     return NULL_TREE;
 383
 384   if (TYPE_TO_RUNTIME_MAP (output_class) == NULL)
 385     TYPE_TO_RUNTIME_MAP (output_class) = java_treetreehash_create (10);
 386
 387   slot = java_treetreehash_new (TYPE_TO_RUNTIME_MAP (output_class), type);
 388   if (*slot != NULL)
 389     return TREE_VALUE (*slot);
 390
 391   if (is_compiled_class (type) && !flag_indirect_dispatch)
 392     {
 393       name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type)));
 394       buf = (char *) alloca (strlen (name) + 5);
 395       sprintf (buf, "%s_ref", name);
 396       decl = build_decl (input_location,
 397                          VAR_DECL, get_identifier (buf), ptr_type_node);
 398       TREE_STATIC (decl) = 1;
 399       DECL_ARTIFICIAL (decl) = 1;
 400       DECL_IGNORED_P (decl) = 1;
 401       TREE_READONLY (decl) = 1;
 402       TREE_THIS_VOLATILE (decl) = 0;
 403       DECL_INITIAL (decl) = build_class_ref (type);
 404       layout_decl (decl, 0);
 405       pushdecl (decl);
 406       exp = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (decl)), decl);
 407     }
 408   else
 409     {
 410       utf8_ref = build_utf8_ref (DECL_NAME (TYPE_NAME (type)));
 411       name = IDENTIFIER_POINTER (DECL_NAME (TREE_OPERAND (utf8_ref, 0)));
 412       buf = (char *) alloca (strlen (name) + 5);
 413       sprintf (buf, "%s_ref", name);
 414       decl = build_decl (input_location,
 415                          VAR_DECL, get_identifier (buf), utf8const_ptr_type);
 416       TREE_STATIC (decl) = 1;
 417       DECL_ARTIFICIAL (decl) = 1;
 418       DECL_IGNORED_P (decl) = 1;
 419       TREE_READONLY (decl) = 1;
 420       TREE_THIS_VOLATILE (decl) = 0;
 421       layout_decl (decl, 0);
 422       pushdecl (decl);
 423       exp = build1 (ADDR_EXPR, build_pointer_type (utf8const_ptr_type), decl);
 424       CONSTRUCTOR_APPEND_ELT (TYPE_CATCH_CLASSES (output_class),
 425                               NULL_TREE,
 426                               make_catch_class_record (exp, utf8_ref));
 427     }
 428
 429   exp = convert (ptr_type_node, exp);
 430
 431   *slot = tree_cons (type, exp, NULL_TREE);
 432
 433   return exp;
 434 }
 435
 436 int
 437 expand_catch_class (treetreehash_entry **entry, int)
 438 {
 439   struct treetreehash_entry *ite = *entry;
 440   tree addr = TREE_VALUE ((tree)ite->value);
 441   tree decl;
 442   STRIP_NOPS (addr);
 443   decl = TREE_OPERAND (addr, 0);
 444   rest_of_decl_compilation (decl, global_bindings_p (), 0);
 445   return true;
 446 }
 447
 448 /* For every class in the TYPE_TO_RUNTIME_MAP, expand the
 449    corresponding object that is used by the runtime type matcher.  */
 450
 451 void
 452 java_expand_catch_classes (tree this_class)
 453 {
 454   if (TYPE_TO_RUNTIME_MAP (this_class))
 455     TYPE_TO_RUNTIME_MAP (this_class)->traverse<int, expand_catch_class> (0);
 456 }
 457
 458 /* Build and push the variable that will hold the exception object
 459    within this function.  */
 460
 461 static tree
 462 build_exception_object_var (void)
 463 {
 464   tree decl = DECL_FUNCTION_EXC_OBJ (current_function_decl);
 465   if (decl == NULL)
 466     {
 467       decl = build_decl (DECL_SOURCE_LOCATION (current_function_decl),
 468                          VAR_DECL, get_identifier ("#exc_obj"), ptr_type_node);
 469       DECL_IGNORED_P (decl) = 1;
 470       DECL_ARTIFICIAL (decl) = 1;
 471
 472       DECL_FUNCTION_EXC_OBJ (current_function_decl) = decl;
 473       pushdecl_function_level (decl);
 474     }
 475   return decl;
 476 }
 477
 478 /* Build a reference to the jthrowable object being carried in the
 479    exception header.  */
 480
 481 tree
 482 build_exception_object_ref (tree type)
 483 {
 484   tree obj;
 485
 486   /* Java only passes object via pointer and doesn't require adjusting.
 487      The java object is immediately before the generic exception header.  */
 488   obj = build_exception_object_var ();
 489   obj = fold_convert (build_pointer_type (type), obj);
 490   obj = fold_build_pointer_plus (obj,
 491                 fold_build1 (NEGATE_EXPR, sizetype,
 492                              TYPE_SIZE_UNIT (TREE_TYPE (obj))));
 493   obj = build1 (INDIRECT_REF, type, obj);
 494
 495   return obj;
 496 }
 497
 498 /* If there are any handlers for this range, issue end of range,
 499    and then all handler blocks */
 500 void
 501 expand_end_java_handler (struct eh_range *range)
 502 {
 503   tree handler = range->handlers;
 504   if (handler)
 505     {
 506       tree exc_obj = build_exception_object_var ();
 507       tree catches = make_node (STATEMENT_LIST);
 508       tree_stmt_iterator catches_i = tsi_last (catches);
 509       tree *body;
 510
 511       for (; handler; handler = TREE_CHAIN (handler))
 512         {
 513           tree type, eh_type, x;
 514           tree stmts = make_node (STATEMENT_LIST);
 515           tree_stmt_iterator stmts_i = tsi_last (stmts);
 516
 517           type = TREE_PURPOSE (handler);
 518           if (type == NULL)
 519             type = throwable_type_node;
 520           eh_type = prepare_eh_table_type (type);
 521
 522           x = build_call_expr (builtin_decl_explicit (BUILT_IN_EH_POINTER),
 523                                1, integer_zero_node);
 524           x = build2 (MODIFY_EXPR, void_type_node, exc_obj, x);
 525           tsi_link_after (&stmts_i, x, TSI_CONTINUE_LINKING);
 526
 527           x = build1 (GOTO_EXPR, void_type_node, TREE_VALUE (handler));
 528           tsi_link_after (&stmts_i, x, TSI_CONTINUE_LINKING);
 529
 530           x = build2 (CATCH_EXPR, void_type_node, eh_type, stmts);
 531           tsi_link_after (&catches_i, x, TSI_CONTINUE_LINKING);
 532
 533           /* Throwable can match anything in Java, and therefore
 534              any subsequent handlers are unreachable.  */
 535           /* ??? If we're assured of no foreign language exceptions,
 536              we'd be better off using NULL as the exception type
 537              for the catch.  */
 538           if (type == throwable_type_node)
 539             break;
 540         }
 541
 542       body = get_stmts ();
 543       *body = build2 (TRY_CATCH_EXPR, void_type_node, *body, catches);
 544     }
 545
 546 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 547   indent ();
 548   fprintf (stderr, "expand end handler pc %d <-- %d\n",
 549            current_pc, range->start_pc);
 550 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 551 }
 552
 553 /* Recursive helper routine for maybe_start_handlers. */
 554
 555 static void
 556 check_start_handlers (struct eh_range *range, int pc)
 557 {
 558   if (range != NULL_EH_RANGE && range->start_pc == pc)
 559     {
 560       check_start_handlers (range->outer, pc);
 561       if (!range->expanded)
 562         expand_start_java_handler (range);
 563     }
 564 }
 565
 566
 567 /* Routine to see if exception handling is turned on.
 568    DO_WARN is nonzero if we want to inform the user that exception
 569    handling is turned off.
 570
 571    This is used to ensure that -fexceptions has been specified if the
 572    compiler tries to use any exception-specific functions.  */
 573
 574 static inline int
 575 doing_eh (void)
 576 {
 577   if (! flag_exceptions)
 578     {
 579       static int warned = 0;
 580       if (! warned)
 581         {
 582           error ("exception handling disabled, use -fexceptions to enable");
 583           warned = 1;
 584         }
 585       return 0;
 586     }
 587   return 1;
 588 }
 589
 590 static struct eh_range *current_range;
 591
 592 /* Emit any start-of-try-range starting at start_pc and ending after
 593    end_pc. */
 594
 595 void
 596 maybe_start_try (int start_pc, int end_pc)
 597 {
 598   struct eh_range *range;
 599   if (! doing_eh ())
 600     return;
 601
 602   range = find_handler (start_pc);
 603   while (range != NULL_EH_RANGE && range->start_pc == start_pc
 604          && range->end_pc < end_pc)
 605     range = range->outer;
 606
 607   current_range = range;
 608   check_start_handlers (range, start_pc);
 609 }
 610