gcc/java/except.c

   1 /* Handle exceptions for GNU compiler for the Java(TM) language.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005,
   3    2007, 2008 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License 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 Java and all Java-based marks are trademarks or registered trademarks
  22 of Sun Microsystems, Inc. in the United States and other countries.
  23 The Free Software Foundation is independent of Sun Microsystems, Inc.  */
  24
  25 #include "config.h"
  26 #include "system.h"
  27 #include "coretypes.h"
  28 #include "tm.h"
  29 #include "tree.h"
  30 #include "real.h"
  31 #include "rtl.h"
  32 #include "java-tree.h"
  33 #include "javaop.h"
  34 #include "java-opcodes.h"
  35 #include "jcf.h"
  36 #include "function.h"
  37 #include "except.h"
  38 #include "java-except.h"
  39 #include "toplev.h"
  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, 1);
 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       TYPE_CATCH_CLASSES (output_class) =
 425         tree_cons (NULL, make_catch_class_record (exp, utf8_ref),
 426                    TYPE_CATCH_CLASSES (output_class));
 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 static int
 437 expand_catch_class (void **entry, void *x ATTRIBUTE_UNUSED)
 438 {
 439   struct treetreehash_entry *ite = (struct treetreehash_entry *) *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     htab_traverse
 456       (TYPE_TO_RUNTIME_MAP (this_class),
 457        expand_catch_class, NULL);
 458 }
 459
 460 /* Build a reference to the jthrowable object being carried in the
 461    exception header.  */
 462
 463 tree
 464 build_exception_object_ref (tree type)
 465 {
 466   tree obj;
 467
 468   /* Java only passes object via pointer and doesn't require adjusting.
 469      The java object is immediately before the generic exception header.  */
 470   obj = build0 (EXC_PTR_EXPR, build_pointer_type (type));
 471   obj = build2 (POINTER_PLUS_EXPR, TREE_TYPE (obj), obj,
 472                 fold_build1 (NEGATE_EXPR, sizetype,
 473                              TYPE_SIZE_UNIT (TREE_TYPE (obj))));
 474   obj = build1 (INDIRECT_REF, type, obj);
 475
 476   return obj;
 477 }
 478
 479 /* If there are any handlers for this range, issue end of range,
 480    and then all handler blocks */
 481 void
 482 expand_end_java_handler (struct eh_range *range)
 483 {
 484   tree handler = range->handlers;
 485
 486   for ( ; handler != NULL_TREE; handler = TREE_CHAIN (handler))
 487     {
 488       /* For bytecode we treat exceptions a little unusually.  A
 489          `finally' clause looks like an ordinary exception handler for
 490          Throwable.  The reason for this is that the bytecode has
 491          already expanded the finally logic, and we would have to do
 492          extra (and difficult) work to get this to look like a
 493          gcc-style finally clause.  */
 494       tree type = TREE_PURPOSE (handler);
 495       if (type == NULL)
 496         type = throwable_type_node;
 497       type = prepare_eh_table_type (type);
 498
 499       {
 500         tree catch_expr = build2 (CATCH_EXPR, void_type_node, type,
 501                                   build1 (GOTO_EXPR, void_type_node,
 502                                           TREE_VALUE (handler)));
 503         tree try_catch_expr = build2 (TRY_CATCH_EXPR, void_type_node,
 504                                       *get_stmts (), catch_expr);
 505         *get_stmts () = try_catch_expr;
 506       }
 507     }
 508 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 509   indent ();
 510   fprintf (stderr, "expand end handler pc %d <-- %d\n",
 511            current_pc, range->start_pc);
 512 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 513 }
 514
 515 /* Recursive helper routine for maybe_start_handlers. */
 516
 517 static void
 518 check_start_handlers (struct eh_range *range, int pc)
 519 {
 520   if (range != NULL_EH_RANGE && range->start_pc == pc)
 521     {
 522       check_start_handlers (range->outer, pc);
 523       if (!range->expanded)
 524         expand_start_java_handler (range);
 525     }
 526 }
 527
 528
 529 static struct eh_range *current_range;
 530
 531 /* Emit any start-of-try-range starting at start_pc and ending after
 532    end_pc. */
 533
 534 void
 535 maybe_start_try (int start_pc, int end_pc)
 536 {
 537   struct eh_range *range;
 538   if (! doing_eh (1))
 539     return;
 540
 541   range = find_handler (start_pc);
 542   while (range != NULL_EH_RANGE && range->start_pc == start_pc
 543          && range->end_pc < end_pc)
 544     range = range->outer;
 545
 546   current_range = range;
 547   check_start_handlers (range, start_pc);
 548 }
 549