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    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 2, 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 COPYING.  If not, write to
  19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  20 Boston, MA 02110-1301, USA.
  21
  22 Java and all Java-based marks are trademarks or registered trademarks
  23 of Sun Microsystems, Inc. in the United States and other countries.
  24 The Free Software Foundation is independent of Sun Microsystems, Inc.  */
  25
  26 #include "config.h"
  27 #include "system.h"
  28 #include "coretypes.h"
  29 #include "tm.h"
  30 #include "tree.h"
  31 #include "real.h"
  32 #include "rtl.h"
  33 #include "java-tree.h"
  34 #include "javaop.h"
  35 #include "java-opcodes.h"
  36 #include "jcf.h"
  37 #include "function.h"
  38 #include "except.h"
  39 #include "java-except.h"
  40 #include "toplev.h"
  41
  42 static void expand_start_java_handler (struct eh_range *);
  43 static struct eh_range *find_handler_in_range (int, struct eh_range *,
  44                                                struct eh_range *);
  45 static void check_start_handlers (struct eh_range *, int);
  46 static void free_eh_ranges (struct eh_range *range);
  47
  48 struct eh_range *current_method_handlers;
  49
  50 struct eh_range *current_try_block = NULL;
  51
  52 /* These variables are used to speed up find_handler. */
  53
  54 static int cache_range_start, cache_range_end;
  55 static struct eh_range *cache_range;
  56 static struct eh_range *cache_next_child;
  57
  58 /* A dummy range that represents the entire method. */
  59
  60 struct eh_range whole_range;
  61
  62 /* Check the invariants of the structure we're using to contain
  63    exception regions.  Either returns true or fails an assertion
  64    check.  */
  65
  66 bool
  67 sanity_check_exception_range (struct eh_range *range)
  68 {
  69   struct eh_range *ptr = range->first_child;
  70   for (; ptr; ptr = ptr->next_sibling)
  71     {
  72       gcc_assert (ptr->outer == range
  73                   && ptr->end_pc > ptr->start_pc);
  74       if (ptr->next_sibling)
  75         gcc_assert (ptr->next_sibling->start_pc >= ptr->end_pc);
  76       gcc_assert (ptr->start_pc >= ptr->outer->start_pc
  77                   && ptr->end_pc <=  ptr->outer->end_pc);
  78       (void) sanity_check_exception_range (ptr);
  79     }
  80   return true;
  81 }
  82
  83 #if defined(DEBUG_JAVA_BINDING_LEVELS)
  84 extern int is_class_level;
  85 extern int current_pc;
  86 extern int binding_depth;
  87 extern void indent (void);
  88 static void
  89 print_ranges (struct eh_range *range)
  90 {
  91   if (! range)
  92     return;
  93
  94   struct eh_range *child = range->first_child;
  95
  96   indent ();
  97   fprintf (stderr, "handler pc %d --> %d ", range->start_pc, range->end_pc);
  98
  99   tree handler = range->handlers;
 100   for ( ; handler != NULL_TREE; handler = TREE_CHAIN (handler))
 101     {
 102       tree type = TREE_PURPOSE (handler);
 103       if (type == NULL)
 104         type = throwable_type_node;
 105       fprintf (stderr, " type=%s ", IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type))));
 106     }
 107   fprintf (stderr, "\n");
 108
 109   int saved = binding_depth;
 110   binding_depth++;
 111   print_ranges (child);
 112   binding_depth = saved;
 113
 114   print_ranges (range->next_sibling);
 115 }
 116 #endif
 117
 118 /* Search for the most specific eh_range containing PC.
 119    Assume PC is within RANGE.
 120    CHILD is a list of children of RANGE such that any
 121    previous children have end_pc values that are too low. */
 122
 123 static struct eh_range *
 124 find_handler_in_range (int pc, struct eh_range *range, struct eh_range *child)
 125 {
 126   for (; child != NULL;  child = child->next_sibling)
 127     {
 128       if (pc < child->start_pc)
 129         break;
 130       if (pc < child->end_pc)
 131         return find_handler_in_range (pc, child, child->first_child);
 132     }
 133   cache_range = range;
 134   cache_range_start = pc;
 135   cache_next_child = child;
 136   cache_range_end = child == NULL ? range->end_pc : child->start_pc;
 137   return range;
 138 }
 139
 140 /* Find the inner-most handler that contains PC. */
 141
 142 struct eh_range *
 143 find_handler (int pc)
 144 {
 145   struct eh_range *h;
 146   if (pc >= cache_range_start)
 147     {
 148       h = cache_range;
 149       if (pc < cache_range_end)
 150         return h;
 151       while (pc >= h->end_pc)
 152         {
 153           cache_next_child = h->next_sibling;
 154           h = h->outer;
 155         }
 156     }
 157   else
 158     {
 159       h = &whole_range;
 160       cache_next_child = h->first_child;
 161     }
 162   return find_handler_in_range (pc, h, cache_next_child);
 163 }
 164
 165 static void
 166 free_eh_ranges (struct eh_range *range)
 167 {
 168   while (range)
 169     {
 170       struct eh_range *next = range->next_sibling;
 171       free_eh_ranges (range->first_child);
 172       if (range != &whole_range)
 173         free (range);
 174       range = next;
 175     }
 176 }
 177
 178 /* Called to re-initialize the exception machinery for a new method. */
 179
 180 void
 181 method_init_exceptions (void)
 182 {
 183   free_eh_ranges (&whole_range);
 184   whole_range.start_pc = 0;
 185   whole_range.end_pc = DECL_CODE_LENGTH (current_function_decl) + 1;
 186   whole_range.outer = NULL;
 187   whole_range.first_child = NULL;
 188   whole_range.next_sibling = NULL;
 189   cache_range_start = 0xFFFFFF;
 190 }
 191
 192 /* Split an exception range into two at PC.  The sub-ranges that
 193    belong to the range are split and distributed between the two new
 194    ranges.  */
 195
 196 static void
 197 split_range (struct eh_range *range, int pc)
 198 {
 199   struct eh_range *ptr;
 200   struct eh_range **first_child, **second_child;
 201   struct eh_range *h;
 202
 203   /* First, split all the sub-ranges.  */
 204   for (ptr = range->first_child; ptr; ptr = ptr->next_sibling)
 205     {
 206       if (pc > ptr->start_pc
 207           && pc < ptr->end_pc)
 208         {
 209           split_range (ptr, pc);
 210         }
 211     }
 212
 213   /* Create a new range.  */
 214   h = XNEW (struct eh_range);
 215
 216   h->start_pc = pc;
 217   h->end_pc = range->end_pc;
 218   h->next_sibling = range->next_sibling;
 219   range->next_sibling = h;
 220   range->end_pc = pc;
 221   h->handlers = build_tree_list (TREE_PURPOSE (range->handlers),
 222                                  TREE_VALUE (range->handlers));
 223   h->next_sibling = NULL;
 224   h->expanded = 0;
 225   h->stmt = NULL;
 226   h->outer = range->outer;
 227   h->first_child = NULL;
 228
 229   ptr = range->first_child;
 230   first_child = &range->first_child;
 231   second_child = &h->first_child;
 232
 233   /* Distribute the sub-ranges between the two new ranges.  */
 234   for (ptr = range->first_child; ptr; ptr = ptr->next_sibling)
 235     {
 236       if (ptr->start_pc < pc)
 237         {
 238           *first_child = ptr;
 239           ptr->outer = range;
 240           first_child = &ptr->next_sibling;
 241         }
 242       else
 243         {
 244           *second_child = ptr;
 245           ptr->outer = h;
 246           second_child = &ptr->next_sibling;
 247         }
 248     }
 249   *first_child = NULL;
 250   *second_child = NULL;
 251 }
 252
 253
 254 /* Add an exception range.
 255
 256    There are some missed optimization opportunities here.  For
 257    example, some bytecode obfuscators generate seemingly
 258    nonoverlapping exception ranges which, when coalesced, do in fact
 259    nest correctly.  We could merge these, but we'd have to fix up all
 260    the enclosed regions first and perhaps create a new range anyway if
 261    it overlapped existing ranges.
 262
 263    Also, we don't attempt to detect the case where two previously
 264    added disjoint ranges could be coalesced by a new range.  */
 265
 266 void
 267 add_handler (int start_pc, int end_pc, tree handler, tree type)
 268 {
 269   struct eh_range *ptr, *h;
 270   struct eh_range **first_child, **prev;
 271
 272   /* First, split all the existing ranges that we need to enclose.  */
 273   for (ptr = whole_range.first_child; ptr; ptr = ptr->next_sibling)
 274     {
 275       if (start_pc > ptr->start_pc
 276           && start_pc < ptr->end_pc)
 277         {
 278           split_range (ptr, start_pc);
 279         }
 280
 281       if (end_pc > ptr->start_pc
 282           && end_pc < ptr->end_pc)
 283         {
 284           split_range (ptr, end_pc);
 285         }
 286
 287       if (ptr->start_pc >= end_pc)
 288         break;
 289     }
 290
 291   /* Create the new range.  */
 292   h = XNEW (struct eh_range);
 293   first_child = &h->first_child;
 294
 295   h->start_pc = start_pc;
 296   h->end_pc = end_pc;
 297   h->first_child = NULL;
 298   h->outer = NULL_EH_RANGE;
 299   h->handlers = build_tree_list (type, handler);
 300   h->next_sibling = NULL;
 301   h->expanded = 0;
 302   h->stmt = NULL;
 303
 304   /* Find every range at the top level that will be a sub-range of the
 305      range we're inserting and make it so.  */
 306   {
 307     struct eh_range **prev = &whole_range.first_child;
 308     for (ptr = *prev; ptr;)
 309       {
 310         struct eh_range *next = ptr->next_sibling;
 311
 312         if (ptr->start_pc >= end_pc)
 313           break;
 314
 315         if (ptr->start_pc < start_pc)
 316           {
 317             prev = &ptr->next_sibling;
 318           }
 319         else if (ptr->start_pc >= start_pc
 320                  && ptr->start_pc < end_pc)
 321           {
 322             *prev = next;
 323             *first_child = ptr;
 324             first_child = &ptr->next_sibling;
 325             ptr->outer = h;
 326             ptr->next_sibling = NULL;
 327           }
 328
 329         ptr = next;
 330       }
 331   }
 332
 333   /* Find the right place to insert the new range.  */
 334   prev = &whole_range.first_child;
 335   for (ptr = *prev; ptr; prev = &ptr->next_sibling, ptr = ptr->next_sibling)
 336     {
 337       gcc_assert (ptr->outer == NULL_EH_RANGE);
 338       if (ptr->start_pc >= start_pc)
 339         break;
 340     }
 341
 342   /* And insert it there.  */
 343   *prev = h;
 344   if (ptr)
 345     {
 346       h->next_sibling = ptr;
 347       h->outer = ptr->outer;
 348     }
 349 }
 350
 351
 352 /* if there are any handlers for this range, issue start of region */
 353 static void
 354 expand_start_java_handler (struct eh_range *range)
 355 {
 356 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 357   indent ();
 358   fprintf (stderr, "expand start handler pc %d --> %d\n",
 359            current_pc, range->end_pc);
 360 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 361   pushlevel (0);
 362   register_exception_range (range,  range->start_pc, range->end_pc);
 363   range->expanded = 1;
 364 }
 365
 366 tree
 367 prepare_eh_table_type (tree type)
 368 {
 369   tree exp;
 370   tree *slot;
 371   const char *name;
 372   char *buf;
 373   tree decl;
 374   tree utf8_ref;
 375
 376   /* The "type" (match_info) in a (Java) exception table is a pointer to:
 377    * a) NULL - meaning match any type in a try-finally.
 378    * b) a pointer to a pointer to a class.
 379    * c) a pointer to a pointer to a utf8_ref.  The pointer is
 380    * rewritten to point to the appropriate class.  */
 381
 382   if (type == NULL_TREE)
 383     return NULL_TREE;
 384
 385   if (TYPE_TO_RUNTIME_MAP (output_class) == NULL)
 386     TYPE_TO_RUNTIME_MAP (output_class) = java_treetreehash_create (10, 1);
 387
 388   slot = java_treetreehash_new (TYPE_TO_RUNTIME_MAP (output_class), type);
 389   if (*slot != NULL)
 390     return TREE_VALUE (*slot);
 391
 392   if (is_compiled_class (type) && !flag_indirect_dispatch)
 393     {
 394       name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type)));
 395       buf = alloca (strlen (name) + 5);
 396       sprintf (buf, "%s_ref", name);
 397       decl = build_decl (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 = alloca (strlen (name) + 5);
 413       sprintf (buf, "%s_ref", name);
 414       decl = build_decl (VAR_DECL, get_identifier (buf), utf8const_ptr_type);
 415       TREE_STATIC (decl) = 1;
 416       DECL_ARTIFICIAL (decl) = 1;
 417       DECL_IGNORED_P (decl) = 1;
 418       TREE_READONLY (decl) = 1;
 419       TREE_THIS_VOLATILE (decl) = 0;
 420       layout_decl (decl, 0);
 421       pushdecl (decl);
 422       exp = build1 (ADDR_EXPR, build_pointer_type (utf8const_ptr_type), decl);
 423       TYPE_CATCH_CLASSES (output_class) =
 424         tree_cons (NULL, make_catch_class_record (exp, utf8_ref),
 425                    TYPE_CATCH_CLASSES (output_class));
 426     }
 427
 428   exp = convert (ptr_type_node, exp);
 429
 430   *slot = tree_cons (type, exp, NULL_TREE);
 431
 432   return exp;
 433 }
 434
 435 static int
 436 expand_catch_class (void **entry, void *x ATTRIBUTE_UNUSED)
 437 {
 438   struct treetreehash_entry *ite = (struct treetreehash_entry *) *entry;
 439   tree addr = TREE_VALUE ((tree)ite->value);
 440   tree decl;
 441   STRIP_NOPS (addr);
 442   decl = TREE_OPERAND (addr, 0);
 443   rest_of_decl_compilation (decl, global_bindings_p (), 0);
 444   return true;
 445 }
 446
 447 /* For every class in the TYPE_TO_RUNTIME_MAP, expand the
 448    corresponding object that is used by the runtime type matcher.  */
 449
 450 void
 451 java_expand_catch_classes (tree this_class)
 452 {
 453   if (TYPE_TO_RUNTIME_MAP (this_class))
 454     htab_traverse
 455       (TYPE_TO_RUNTIME_MAP (this_class),
 456        expand_catch_class, NULL);
 457 }
 458
 459 /* Build a reference to the jthrowable object being carried in the
 460    exception header.  */
 461
 462 tree
 463 build_exception_object_ref (tree type)
 464 {
 465   tree obj;
 466
 467   /* Java only passes object via pointer and doesn't require adjusting.
 468      The java object is immediately before the generic exception header.  */
 469   obj = build0 (EXC_PTR_EXPR, build_pointer_type (type));
 470   obj = build2 (MINUS_EXPR, TREE_TYPE (obj), obj,
 471                 TYPE_SIZE_UNIT (TREE_TYPE (obj)));
 472   obj = build1 (INDIRECT_REF, type, obj);
 473
 474   return obj;
 475 }
 476
 477 /* If there are any handlers for this range, isssue end of range,
 478    and then all handler blocks */
 479 void
 480 expand_end_java_handler (struct eh_range *range)
 481 {
 482   tree handler = range->handlers;
 483
 484   for ( ; handler != NULL_TREE; handler = TREE_CHAIN (handler))
 485     {
 486       /* For bytecode we treat exceptions a little unusually.  A
 487          `finally' clause looks like an ordinary exception handler for
 488          Throwable.  The reason for this is that the bytecode has
 489          already expanded the finally logic, and we would have to do
 490          extra (and difficult) work to get this to look like a
 491          gcc-style finally clause.  */
 492       tree type = TREE_PURPOSE (handler);
 493       if (type == NULL)
 494         type = throwable_type_node;
 495       type = prepare_eh_table_type (type);
 496
 497       {
 498         tree catch_expr = build2 (CATCH_EXPR, void_type_node, type,
 499                                   build1 (GOTO_EXPR, void_type_node,
 500                                           TREE_VALUE (handler)));
 501         tree try_catch_expr = build2 (TRY_CATCH_EXPR, void_type_node,
 502                                       *get_stmts (), catch_expr);
 503         *get_stmts () = try_catch_expr;
 504       }
 505     }
 506 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 507   indent ();
 508   fprintf (stderr, "expand end handler pc %d <-- %d\n",
 509            current_pc, range->start_pc);
 510 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 511 }
 512
 513 /* Recursive helper routine for maybe_start_handlers. */
 514
 515 static void
 516 check_start_handlers (struct eh_range *range, int pc)
 517 {
 518   if (range != NULL_EH_RANGE && range->start_pc == pc)
 519     {
 520       check_start_handlers (range->outer, pc);
 521       if (!range->expanded)
 522         expand_start_java_handler (range);
 523     }
 524 }
 525
 526
 527 static struct eh_range *current_range;
 528
 529 /* Emit any start-of-try-range starting at start_pc and ending after
 530    end_pc. */
 531
 532 void
 533 maybe_start_try (int start_pc, int end_pc)
 534 {
 535   struct eh_range *range;
 536   if (! doing_eh (1))
 537     return;
 538
 539   range = find_handler (start_pc);
 540   while (range != NULL_EH_RANGE && range->start_pc == start_pc
 541          && range->end_pc < end_pc)
 542     range = range->outer;
 543
 544   current_range = range;
 545   check_start_handlers (range, start_pc);
 546 }
 547