gcc/java/except.c

   1 /* Handle exceptions for GNU compiler for the Java(TM) language.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003
   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, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, 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 void expand_end_java_handler (struct eh_range *);
  44 static struct eh_range *find_handler_in_range (int, struct eh_range *,
  45                                                struct eh_range *);
  46 static void link_handler (struct eh_range *, struct eh_range *);
  47 static void check_start_handlers (struct eh_range *, int);
  48 static void free_eh_ranges (struct eh_range *range);
  49
  50 struct eh_range *current_method_handlers;
  51
  52 struct eh_range *current_try_block = NULL;
  53
  54 struct eh_range *eh_range_freelist = NULL;
  55
  56 /* These variables are used to speed up find_handler. */
  57
  58 static int cache_range_start, cache_range_end;
  59 static struct eh_range *cache_range;
  60 static struct eh_range *cache_next_child;
  61
  62 /* A dummy range that represents the entire method. */
  63
  64 struct eh_range whole_range;
  65
  66 #if defined(DEBUG_JAVA_BINDING_LEVELS)
  67 extern int binding_depth;
  68 extern int is_class_level;
  69 extern int current_pc;
  70 extern void indent ();
  71
  72 #endif
  73
  74 /* Search for the most specific eh_range containing PC.
  75    Assume PC is within RANGE.
  76    CHILD is a list of children of RANGE such that any
  77    previous children have end_pc values that are too low. */
  78
  79 static struct eh_range *
  80 find_handler_in_range (int pc, struct eh_range *range, struct eh_range *child)
  81 {
  82   for (; child != NULL;  child = child->next_sibling)
  83     {
  84       if (pc < child->start_pc)
  85         break;
  86       if (pc < child->end_pc)
  87         return find_handler_in_range (pc, child, child->first_child);
  88     }
  89   cache_range = range;
  90   cache_range_start = pc;
  91   cache_next_child = child;
  92   cache_range_end = child == NULL ? range->end_pc : child->start_pc;
  93   return range;
  94 }
  95
  96 /* Find the inner-most handler that contains PC. */
  97
  98 struct eh_range *
  99 find_handler (int pc)
 100 {
 101   struct eh_range *h;
 102   if (pc >= cache_range_start)
 103     {
 104       h = cache_range;
 105       if (pc < cache_range_end)
 106         return h;
 107       while (pc >= h->end_pc)
 108         {
 109           cache_next_child = h->next_sibling;
 110           h = h->outer;
 111         }
 112     }
 113   else
 114     {
 115       h = &whole_range;
 116       cache_next_child = h->first_child;
 117     }
 118   return find_handler_in_range (pc, h, cache_next_child);
 119 }
 120
 121 /* Recursive helper routine for check_nested_ranges. */
 122
 123 static void
 124 link_handler (struct eh_range *range, struct eh_range *outer)
 125 {
 126   struct eh_range **ptr;
 127
 128   if (range->start_pc == outer->start_pc && range->end_pc == outer->end_pc)
 129     {
 130       outer->handlers = chainon (outer->handlers, range->handlers);
 131       return;
 132     }
 133
 134   /* If the new range completely encloses the `outer' range, then insert it
 135      between the outer range and its parent.  */
 136   if (range->start_pc <= outer->start_pc && range->end_pc >= outer->end_pc)
 137     {
 138       range->outer = outer->outer;
 139       range->next_sibling = NULL;
 140       range->first_child = outer;
 141       {
 142         struct eh_range **pr = &(outer->outer->first_child);
 143         while (*pr != outer)
 144           pr = &(*pr)->next_sibling;
 145         *pr = range;
 146       }
 147       outer->outer = range;
 148       return;
 149     }
 150
 151   /* Handle overlapping ranges by splitting the new range.  */
 152   if (range->start_pc < outer->start_pc || range->end_pc > outer->end_pc)
 153     {
 154       struct eh_range *h = xmalloc (sizeof (struct eh_range));
 155       if (range->start_pc < outer->start_pc)
 156         {
 157           h->start_pc = range->start_pc;
 158           h->end_pc = outer->start_pc;
 159           range->start_pc = outer->start_pc;
 160         }
 161       else
 162         {
 163           h->start_pc = outer->end_pc;
 164           h->end_pc = range->end_pc;
 165           range->end_pc = outer->end_pc;
 166         }
 167       h->first_child = NULL;
 168       h->outer = NULL;
 169       h->handlers = build_tree_list (TREE_PURPOSE (range->handlers),
 170                                      TREE_VALUE (range->handlers));
 171       h->next_sibling = NULL;
 172       h->expanded = 0;
 173       /* Restart both from the top to avoid having to make this
 174          function smart about reentrancy.  */
 175       link_handler (h, &whole_range);
 176       link_handler (range, &whole_range);
 177       return;
 178     }
 179
 180   ptr = &outer->first_child;
 181   for (;; ptr = &(*ptr)->next_sibling)
 182     {
 183       if (*ptr == NULL || range->end_pc <= (*ptr)->start_pc)
 184         {
 185           range->next_sibling = *ptr;
 186           range->first_child = NULL;
 187           range->outer = outer;
 188           *ptr = range;
 189           return;
 190         }
 191       else if (range->start_pc < (*ptr)->end_pc)
 192         {
 193           link_handler (range, *ptr);
 194           return;
 195         }
 196       /* end_pc > (*ptr)->start_pc && start_pc >= (*ptr)->end_pc. */
 197     }
 198 }
 199
 200 /* The first pass of exception range processing (calling add_handler)
 201    constructs a linked list of exception ranges.  We turn this into
 202    the data structure expected by the rest of the code, and also
 203    ensure that exception ranges are properly nested.  */
 204
 205 void
 206 handle_nested_ranges (void)
 207 {
 208   struct eh_range *ptr, *next;
 209
 210   ptr = whole_range.first_child;
 211   whole_range.first_child = NULL;
 212   for (; ptr; ptr = next)
 213     {
 214       next = ptr->next_sibling;
 215       ptr->next_sibling = NULL;
 216       link_handler (ptr, &whole_range);
 217     }
 218 }
 219
 220 /* Free RANGE as well as its children and siblings.  */
 221
 222 static void
 223 free_eh_ranges (struct eh_range *range)
 224 {
 225   while (range)
 226     {
 227       struct eh_range *next = range->next_sibling;
 228       free_eh_ranges (range->first_child);
 229       if (range != &whole_range)
 230         free (range);
 231       range = next;
 232     }
 233 }
 234
 235 /* Called to re-initialize the exception machinery for a new method. */
 236
 237 void
 238 method_init_exceptions (void)
 239 {
 240   free_eh_ranges (&whole_range);
 241   whole_range.start_pc = 0;
 242   whole_range.end_pc = DECL_CODE_LENGTH (current_function_decl) + 1;
 243   whole_range.outer = NULL;
 244   whole_range.first_child = NULL;
 245   whole_range.next_sibling = NULL;
 246   cache_range_start = 0xFFFFFF;
 247 }
 248
 249 /* Add an exception range.  If we already have an exception range
 250    which has the same handler and label, and the new range overlaps
 251    that one, then we simply extend the existing range.  Some bytecode
 252    obfuscators generate seemingly nonoverlapping exception ranges
 253    which, when coalesced, do in fact nest correctly.
 254
 255    This constructs an ordinary linked list which check_nested_ranges()
 256    later turns into the data structure we actually want.
 257
 258    We expect the input to come in order of increasing START_PC.  This
 259    function doesn't attempt to detect the case where two previously
 260    added disjoint ranges could be coalesced by a new range; that is
 261    what the sorting counteracts.  */
 262
 263 void
 264 add_handler (int start_pc, int end_pc, tree handler, tree type)
 265 {
 266   struct eh_range *ptr, *prev = NULL, *h;
 267
 268   for (ptr = whole_range.first_child; ptr; ptr = ptr->next_sibling)
 269     {
 270       if (start_pc >= ptr->start_pc
 271           && start_pc <= ptr->end_pc
 272           && TREE_PURPOSE (ptr->handlers) == type
 273           && TREE_VALUE (ptr->handlers) == handler)
 274         {
 275           /* Already found an overlapping range, so coalesce.  */
 276           ptr->end_pc = MAX (ptr->end_pc, end_pc);
 277           return;
 278         }
 279       prev = ptr;
 280     }
 281
 282   h = xmalloc (sizeof (struct eh_range));
 283   h->start_pc = start_pc;
 284   h->end_pc = end_pc;
 285   h->first_child = NULL;
 286   h->outer = NULL;
 287   h->handlers = build_tree_list (type, handler);
 288   h->next_sibling = NULL;
 289   h->expanded = 0;
 290
 291   if (prev == NULL)
 292     whole_range.first_child = h;
 293   else
 294     prev->next_sibling = h;
 295 }
 296
 297
 298 /* if there are any handlers for this range, issue start of region */
 299 static void
 300 expand_start_java_handler (struct eh_range *range)
 301 {
 302 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 303   indent ();
 304   fprintf (stderr, "expand start handler pc %d --> %d\n",
 305            current_pc, range->end_pc);
 306 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 307   range->expanded = 1;
 308   expand_eh_region_start ();
 309 }
 310
 311 tree
 312 prepare_eh_table_type (tree type)
 313 {
 314   tree exp;
 315   const char *name;
 316   char *buf;
 317   tree decl;
 318   tree utf8_ref;
 319
 320   /* The "type" (match_info) in a (Java) exception table is a pointer to:
 321    * a) NULL - meaning match any type in a try-finally.
 322    * b) a pointer to a pointer to a class.
 323    * c) a pointer to a pointer to a utf8_ref.  The pointer is
 324    * rewritten to point to the appropriate class.  */
 325
 326   if (type == NULL_TREE)
 327     exp = NULL_TREE;
 328   else if (is_compiled_class (type) && !flag_indirect_dispatch)
 329     {
 330       name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type)));
 331       buf = alloca (strlen (name) + 5);
 332       sprintf (buf, "%s_ref", name);
 333       decl = build_decl (VAR_DECL, get_identifier (buf), ptr_type_node);
 334       TREE_STATIC (decl) = 1;
 335       DECL_ARTIFICIAL (decl) = 1;
 336       DECL_IGNORED_P (decl) = 1;
 337       TREE_READONLY (decl) = 1;
 338       TREE_THIS_VOLATILE (decl) = 0;
 339       DECL_INITIAL (decl) = build_class_ref (type);
 340       layout_decl (decl, 0);
 341       pushdecl (decl);
 342       rest_of_decl_compilation (decl, (char*) 0, global_bindings_p (), 0);
 343       make_decl_rtl (decl, (char*) 0);
 344       exp = build1 (ADDR_EXPR, ptr_type_node, decl);
 345     }
 346   else
 347     {
 348       utf8_ref = build_utf8_ref (DECL_NAME (TYPE_NAME (type)));
 349       name = IDENTIFIER_POINTER (DECL_NAME (TREE_OPERAND (utf8_ref, 0)));
 350       buf = alloca (strlen (name) + 5);
 351       sprintf (buf, "%s_ref", name);
 352       decl = build_decl (VAR_DECL, get_identifier (buf), utf8const_ptr_type);
 353       TREE_STATIC (decl) = 1;
 354       DECL_ARTIFICIAL (decl) = 1;
 355       DECL_IGNORED_P (decl) = 1;
 356       TREE_READONLY (decl) = 1;
 357       TREE_THIS_VOLATILE (decl) = 0;
 358       layout_decl (decl, 0);
 359       pushdecl (decl);
 360       rest_of_decl_compilation (decl, (char*) 0, global_bindings_p (), 0);
 361       make_decl_rtl (decl, (char*) 0);
 362       exp = build1 (ADDR_EXPR, build_pointer_type (utf8const_ptr_type), decl);
 363       catch_classes = tree_cons (NULL, make_catch_class_record (exp, utf8_ref), catch_classes);
 364     }
 365   return exp;
 366 }
 367
 368
 369 /* Build a reference to the jthrowable object being carried in the
 370    exception header.  */
 371
 372 tree
 373 build_exception_object_ref (tree type)
 374 {
 375   tree obj;
 376
 377   /* Java only passes object via pointer and doesn't require adjusting.
 378      The java object is immediately before the generic exception header.  */
 379   obj = build (EXC_PTR_EXPR, build_pointer_type (type));
 380   obj = build (MINUS_EXPR, TREE_TYPE (obj), obj,
 381                TYPE_SIZE_UNIT (TREE_TYPE (obj)));
 382   obj = build1 (INDIRECT_REF, type, obj);
 383
 384   return obj;
 385 }
 386
 387 /* If there are any handlers for this range, isssue end of range,
 388    and then all handler blocks */
 389 static void
 390 expand_end_java_handler (struct eh_range *range)
 391 {
 392   tree handler = range->handlers;
 393   force_poplevels (range->start_pc);
 394   expand_start_all_catch ();
 395   for ( ; handler != NULL_TREE; handler = TREE_CHAIN (handler))
 396     {
 397       /* For bytecode we treat exceptions a little unusually.  A
 398          `finally' clause looks like an ordinary exception handler for
 399          Throwable.  The reason for this is that the bytecode has
 400          already expanded the finally logic, and we would have to do
 401          extra (and difficult) work to get this to look like a
 402          gcc-style finally clause.  */
 403       tree type = TREE_PURPOSE (handler);
 404       if (type == NULL)
 405         type = throwable_type_node;
 406
 407       expand_start_catch (type);
 408       expand_goto (TREE_VALUE (handler));
 409       expand_end_catch ();
 410     }
 411   expand_end_all_catch ();
 412 #if defined(DEBUG_JAVA_BINDING_LEVELS)
 413   indent ();
 414   fprintf (stderr, "expand end handler pc %d <-- %d\n",
 415            current_pc, range->start_pc);
 416 #endif /* defined(DEBUG_JAVA_BINDING_LEVELS) */
 417 }
 418
 419 /* Recursive helper routine for maybe_start_handlers. */
 420
 421 static void
 422 check_start_handlers (struct eh_range *range, int pc)
 423 {
 424   if (range != NULL_EH_RANGE && range->start_pc == pc)
 425     {
 426       check_start_handlers (range->outer, pc);
 427       if (!range->expanded)
 428         expand_start_java_handler (range);
 429     }
 430 }
 431
 432
 433 static struct eh_range *current_range;
 434
 435 /* Emit any start-of-try-range starting at start_pc and ending after
 436    end_pc. */
 437
 438 void
 439 maybe_start_try (int start_pc, int end_pc)
 440 {
 441   struct eh_range *range;
 442   if (! doing_eh (1))
 443     return;
 444
 445   range = find_handler (start_pc);
 446   while (range != NULL_EH_RANGE && range->start_pc == start_pc
 447          && range->end_pc < end_pc)
 448     range = range->outer;
 449
 450   current_range = range;
 451   check_start_handlers (range, start_pc);
 452 }
 453
 454 /* Emit any end-of-try-range ending at end_pc and starting before
 455    start_pc. */
 456
 457 void
 458 maybe_end_try (int start_pc, int end_pc)
 459 {
 460   if (! doing_eh (1))
 461     return;
 462
 463   while (current_range != NULL_EH_RANGE && current_range->end_pc <= end_pc
 464          && current_range->start_pc >= start_pc)
 465     {
 466       expand_end_java_handler (current_range);
 467       current_range = current_range->outer;
 468     }
 469 }