gcc/java/java-gimplify.c

   1 /* Java(TM) language-specific gimplification routines.
   2    Copyright (C) 2003, 2004 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 2, 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 COPYING.  If not, write to
  18 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  19 Boston, MA 02110-1301, USA.
  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 "java-tree.h"
  31 #include "tree-dump.h"
  32 #include "tree-gimple.h"
  33 #include "toplev.h"
  34
  35 static tree java_gimplify_labeled_block_expr (tree);
  36 static tree java_gimplify_exit_block_expr (tree);
  37 static tree java_gimplify_case_expr (tree);
  38 static tree java_gimplify_default_expr (tree);
  39 static tree java_gimplify_block (tree);
  40 static tree java_gimplify_new_array_init (tree);
  41 static tree java_gimplify_try_expr (tree);
  42 static enum gimplify_status java_gimplify_modify_expr (tree*, tree*, tree *);
  43 static enum gimplify_status java_gimplify_component_ref (tree*, tree*, tree *);
  44 static enum gimplify_status java_gimplify_self_mod_expr (tree*, tree*, tree *);
  45
  46 static void dump_java_tree (enum tree_dump_index, tree);
  47
  48 /* Convert a Java tree to GENERIC.  */
  49
  50 void
  51 java_genericize (tree fndecl)
  52 {
  53   dump_java_tree (TDI_original, fndecl);
  54
  55   /* Genericize with the gimplifier.  */
  56   gimplify_function_tree (fndecl);
  57
  58   dump_function (TDI_generic, fndecl);
  59 }
  60
  61 /* Gimplify a Java tree.  */
  62
  63 int
  64 java_gimplify_expr (tree *expr_p, tree *pre_p ATTRIBUTE_UNUSED,
  65                     tree *post_p ATTRIBUTE_UNUSED)
  66 {
  67   enum tree_code code = TREE_CODE (*expr_p);
  68
  69   switch (code)
  70     {
  71     case BLOCK:
  72       *expr_p = java_gimplify_block (*expr_p);
  73       break;
  74
  75     case EXPR_WITH_FILE_LOCATION:
  76 #ifdef USE_MAPPED_LOCATION
  77       input_location = EXPR_LOCATION (*expr_p);
  78 #else
  79       input_location.file = EXPR_WFL_FILENAME (*expr_p);
  80       input_location.line = EXPR_WFL_LINENO (*expr_p);
  81 #endif
  82       *expr_p = EXPR_WFL_NODE (*expr_p);
  83       if (EXPR_P (*expr_p))
  84         SET_EXPR_LOCATION (*expr_p, input_location);
  85       break;
  86
  87     case LABELED_BLOCK_EXPR:
  88       *expr_p = java_gimplify_labeled_block_expr (*expr_p);
  89       break;
  90
  91     case EXIT_BLOCK_EXPR:
  92       *expr_p = java_gimplify_exit_block_expr (*expr_p);
  93       break;
  94
  95     case CASE_EXPR:
  96       *expr_p = java_gimplify_case_expr (*expr_p);
  97       break;
  98
  99     case DEFAULT_EXPR:
 100       *expr_p = java_gimplify_default_expr (*expr_p);
 101       break;
 102
 103     case NEW_ARRAY_INIT:
 104       *expr_p = java_gimplify_new_array_init (*expr_p);
 105       break;
 106
 107     case TRY_EXPR:
 108       *expr_p = java_gimplify_try_expr (*expr_p);
 109       break;
 110
 111     case JAVA_CATCH_EXPR:
 112       *expr_p = TREE_OPERAND (*expr_p, 0);
 113       break;
 114
 115     case JAVA_EXC_OBJ_EXPR:
 116       *expr_p = build_exception_object_ref (TREE_TYPE (*expr_p));
 117       break;
 118
 119     case VAR_DECL:
 120       *expr_p = java_replace_reference (*expr_p, /* want_lvalue */ false);
 121       return GS_UNHANDLED;
 122
 123     case MODIFY_EXPR:
 124       return java_gimplify_modify_expr (expr_p, pre_p, post_p);
 125
 126     case SAVE_EXPR:
 127       /* Note that we can see <save_expr NULL> if the save_expr was
 128          already handled by gimplify_save_expr.  */
 129       if (TREE_OPERAND (*expr_p, 0) != NULL_TREE
 130           && TREE_CODE (TREE_OPERAND (*expr_p, 0)) == VAR_DECL)
 131         TREE_OPERAND (*expr_p, 0)
 132           = java_replace_reference (TREE_OPERAND (*expr_p, 0),
 133                                /* want_lvalue */ false);
 134       return GS_UNHANDLED;
 135
 136     case POSTINCREMENT_EXPR:
 137     case POSTDECREMENT_EXPR:
 138     case PREINCREMENT_EXPR:
 139     case PREDECREMENT_EXPR:
 140       return java_gimplify_self_mod_expr (expr_p, pre_p, post_p);
 141
 142     /* These should already be lowered before we get here.  */
 143     case URSHIFT_EXPR:
 144     case COMPARE_EXPR:
 145     case COMPARE_L_EXPR:
 146     case COMPARE_G_EXPR:
 147     case UNARY_PLUS_EXPR:
 148     case NEW_ARRAY_EXPR:
 149     case NEW_ANONYMOUS_ARRAY_EXPR:
 150     case NEW_CLASS_EXPR:
 151     case THIS_EXPR:
 152     case SYNCHRONIZED_EXPR:
 153     case CONDITIONAL_EXPR:
 154     case INSTANCEOF_EXPR:
 155     case CLASS_LITERAL:
 156       gcc_unreachable ();
 157
 158     case COMPONENT_REF:
 159       return java_gimplify_component_ref (expr_p, pre_p, post_p);
 160
 161     default:
 162       /* Java insists on strict left-to-right evaluation of expressions.
 163          A problem may arise if a variable used in the LHS of a binary
 164          operation is altered by an assignment to that value in the RHS
 165          before we've performed the operation.  So, we always copy every
 166          LHS to a temporary variable.
 167
 168          FIXME: Are there any other cases where we should do this?
 169          Parameter lists, maybe?  Or perhaps that's unnecessary because
 170          the front end already generates SAVE_EXPRs.  */
 171
 172       if (TREE_CODE_CLASS (code) == tcc_binary
 173           || TREE_CODE_CLASS (code) == tcc_comparison)
 174         {
 175           enum gimplify_status stat
 176             = gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p, post_p,
 177                              is_gimple_formal_tmp_var, fb_rvalue);
 178           if (stat == GS_ERROR)
 179             return stat;
 180         }
 181
 182       return GS_UNHANDLED;
 183     }
 184
 185   return GS_OK;
 186 }
 187
 188 /* Gimplify a LABELED_BLOCK_EXPR into a LABEL_EXPR following
 189    a (possibly empty) body.  */
 190
 191 static tree
 192 java_gimplify_labeled_block_expr (tree expr)
 193 {
 194   tree body = LABELED_BLOCK_BODY (expr);
 195   tree label = LABELED_BLOCK_LABEL (expr);
 196   tree t;
 197
 198   DECL_CONTEXT (label) = current_function_decl;
 199   t = build1 (LABEL_EXPR, void_type_node, label);
 200   if (body != NULL_TREE)
 201     t = build2 (COMPOUND_EXPR, void_type_node, body, t);
 202   return t;
 203 }
 204
 205 /* Gimplify a EXIT_BLOCK_EXPR into a GOTO_EXPR.  */
 206
 207 static tree
 208 java_gimplify_exit_block_expr (tree expr)
 209 {
 210   tree labeled_block = EXIT_BLOCK_LABELED_BLOCK (expr);
 211   tree label;
 212
 213   /* First operand must be a LABELED_BLOCK_EXPR, which should
 214      already be lowered (or partially lowered) when we get here.  */
 215   gcc_assert (TREE_CODE (labeled_block) == LABELED_BLOCK_EXPR);
 216
 217   label = LABELED_BLOCK_LABEL (labeled_block);
 218   return build1 (GOTO_EXPR, void_type_node, label);
 219 }
 220
 221
 222
 223 static enum gimplify_status
 224 java_gimplify_component_ref (tree *expr_p, tree *pre_p, tree *post_p)
 225 {
 226   if (CLASS_FROM_SOURCE_P (output_class)
 227       && TREE_THIS_VOLATILE (TREE_OPERAND (*expr_p, 1))
 228       && ! TREE_THIS_VOLATILE (*expr_p))
 229   {
 230     enum gimplify_status stat;
 231     tree sync_expr;
 232
 233     /* Special handling for volatile fields.
 234
 235     A load has "acquire" semantics, implying that you can't move up
 236     later operations.  A store has "release" semantics meaning that
 237     earlier operations cannot be delayed past it.
 238
 239     This logic only handles loads: stores are handled in
 240     java_gimplify_modify_expr().
 241
 242     We gimplify this COMPONENT_REF, put the result in a tmp_var, and then
 243     return a COMPOUND_EXPR of the form {__sync_synchronize(); tmp_var}.
 244     This forces __sync_synchronize() to be placed immediately after
 245     loading from the volatile field.
 246
 247     */
 248
 249     TREE_THIS_VOLATILE (*expr_p) = 1;
 250     *expr_p = java_modify_addr_for_volatile (*expr_p);
 251     stat = gimplify_expr (expr_p, pre_p, post_p,
 252                           is_gimple_formal_tmp_var, fb_rvalue);
 253     if (stat == GS_ERROR)
 254       return stat;
 255
 256     sync_expr
 257       = build3 (CALL_EXPR, void_type_node,
 258                 build_address_of (built_in_decls[BUILT_IN_SYNCHRONIZE]),
 259                 NULL_TREE, NULL_TREE);
 260     TREE_SIDE_EFFECTS (sync_expr) = 1;
 261     *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
 262                       sync_expr, *expr_p);
 263     TREE_SIDE_EFFECTS (*expr_p) = 1;
 264   }
 265
 266   return GS_UNHANDLED;
 267 }
 268
 269
 270 static enum gimplify_status
 271 java_gimplify_modify_expr (tree *modify_expr_p, tree *pre_p, tree *post_p)
 272 {
 273   tree modify_expr = *modify_expr_p;
 274   tree lhs = TREE_OPERAND (modify_expr, 0);
 275   tree rhs = TREE_OPERAND (modify_expr, 1);
 276   tree lhs_type = TREE_TYPE (lhs);
 277
 278   if (CLASS_FROM_SOURCE_P (output_class)
 279       && TREE_CODE (lhs) == COMPONENT_REF
 280       && TREE_THIS_VOLATILE (TREE_OPERAND (lhs, 1)))
 281     {
 282       /* Special handling for volatile fields.
 283
 284       A load has "acquire" semantics, implying that you can't move up
 285       later operations.  A store has "release" semantics meaning that
 286       earlier operations cannot be delayed past it.
 287
 288       This logic only handles stores; loads are handled in
 289       java_gimplify_component_ref().
 290
 291       We gimplify the rhs, put the result in a tmp_var, and then return
 292       a MODIFY_EXPR with an rhs of the form {__sync_synchronize(); tmp_var}.
 293       This forces __sync_synchronize() to be placed after evaluating
 294       the rhs and immediately before storing to the volatile field.
 295
 296       */
 297
 298       enum gimplify_status stat;
 299       tree sync_expr
 300         = build3 (CALL_EXPR, void_type_node,
 301                   build_address_of (built_in_decls[BUILT_IN_SYNCHRONIZE]),
 302                   NULL_TREE, NULL_TREE);
 303       TREE_SIDE_EFFECTS (sync_expr) = 1;
 304
 305       stat = gimplify_expr (&rhs, pre_p, post_p,
 306                             is_gimple_formal_tmp_var, fb_rvalue);
 307       if (stat == GS_ERROR)
 308         return stat;
 309
 310       rhs = build2 (COMPOUND_EXPR, TREE_TYPE (rhs),
 311                     sync_expr, rhs);
 312       TREE_SIDE_EFFECTS (rhs) = 1;
 313       TREE_THIS_VOLATILE (lhs) = 1;
 314       lhs = java_modify_addr_for_volatile (lhs);
 315       TREE_OPERAND (modify_expr, 0) = lhs;
 316       TREE_OPERAND (modify_expr, 1) = rhs;
 317     }
 318
 319   /* This is specific to the bytecode compiler.  If a variable has
 320      LOCAL_SLOT_P set, replace an assignment to it with an assignment
 321      to the corresponding variable that holds all its aliases.  */
 322   if (TREE_CODE (lhs) == VAR_DECL
 323       && DECL_LANG_SPECIFIC (lhs)
 324       && LOCAL_SLOT_P (lhs)
 325       && TREE_CODE (lhs_type) == POINTER_TYPE)
 326     {
 327       tree new_lhs = java_replace_reference (lhs, /* want_lvalue */ true);
 328       tree new_rhs = build1 (NOP_EXPR, TREE_TYPE (new_lhs), rhs);
 329       modify_expr = build2 (MODIFY_EXPR, TREE_TYPE (new_lhs),
 330                             new_lhs, new_rhs);
 331       modify_expr = build1 (NOP_EXPR, lhs_type, modify_expr);
 332     }
 333   else if (lhs_type != TREE_TYPE (rhs))
 334     /* Fix up type mismatches to make legal GIMPLE.  These are
 335        generated in several places, in particular null pointer
 336        assignment and subclass assignment.  */
 337     TREE_OPERAND (modify_expr, 1) = convert (lhs_type, rhs);
 338
 339   *modify_expr_p = modify_expr;
 340   return GS_UNHANDLED;
 341 }
 342
 343 /*  Special case handling for volatiles: we need to generate a barrier
 344     between the reading and the writing.  */
 345
 346 static enum gimplify_status
 347 java_gimplify_self_mod_expr (tree *expr_p, tree *pre_p ATTRIBUTE_UNUSED,
 348                              tree *post_p ATTRIBUTE_UNUSED)
 349 {
 350   tree lhs = TREE_OPERAND (*expr_p, 0);
 351
 352   if (TREE_CODE (lhs) == COMPONENT_REF
 353       && TREE_THIS_VOLATILE (TREE_OPERAND (lhs, 1)))
 354     TREE_THIS_VOLATILE (lhs) = 1;
 355
 356   return GS_UNHANDLED;
 357 }
 358
 359
 360 static tree
 361 java_gimplify_case_expr (tree expr)
 362 {
 363   tree label = create_artificial_label ();
 364   return build3 (CASE_LABEL_EXPR, void_type_node,
 365                  TREE_OPERAND (expr, 0), NULL_TREE, label);
 366 }
 367
 368 static tree
 369 java_gimplify_default_expr (tree expr ATTRIBUTE_UNUSED)
 370 {
 371   tree label = create_artificial_label ();
 372   return build3 (CASE_LABEL_EXPR, void_type_node, NULL_TREE, NULL_TREE, label);
 373 }
 374
 375 /* Gimplify BLOCK into a BIND_EXPR.  */
 376
 377 static tree
 378 java_gimplify_block (tree java_block)
 379 {
 380   tree decls = BLOCK_VARS (java_block);
 381   tree body = BLOCK_EXPR_BODY (java_block);
 382   tree outer = gimple_current_bind_expr ();
 383   tree block;
 384
 385   /* Don't bother with empty blocks.  */
 386   if (! body)
 387     return build_empty_stmt ();
 388
 389   if (IS_EMPTY_STMT (body))
 390     return body;
 391
 392   /* Make a proper block.  Java blocks are unsuitable for BIND_EXPR
 393      because they use BLOCK_SUBBLOCKS for another purpose.  */
 394   block = make_node (BLOCK);
 395   BLOCK_VARS (block) = decls;
 396
 397   /* The TREE_USED flag on a block determines whether the debug output
 398      routines generate info for the variables in that block.  */
 399   TREE_USED (block) = 1;
 400
 401   if (outer != NULL_TREE)
 402     {
 403       outer = BIND_EXPR_BLOCK (outer);
 404       BLOCK_SUBBLOCKS (outer) = chainon (BLOCK_SUBBLOCKS (outer), block);
 405     }
 406   BLOCK_EXPR_BODY (java_block) = NULL_TREE;
 407
 408   return build3 (BIND_EXPR, TREE_TYPE (java_block), decls, body, block);
 409 }
 410
 411 /* Gimplify a NEW_ARRAY_INIT node into array/element assignments.  */
 412
 413 static tree
 414 java_gimplify_new_array_init (tree exp)
 415 {
 416   tree array_type = TREE_TYPE (TREE_TYPE (exp));
 417   tree data_field = lookup_field (&array_type, get_identifier ("data"));
 418   tree element_type = TYPE_ARRAY_ELEMENT (array_type);
 419   HOST_WIDE_INT ilength = java_array_type_length (array_type);
 420   tree length = build_int_cst (NULL_TREE, ilength);
 421   tree init = TREE_OPERAND (exp, 0);
 422   tree value;
 423   unsigned HOST_WIDE_INT cnt;
 424
 425   tree array_ptr_type = build_pointer_type (array_type);
 426   tree tmp = create_tmp_var (array_ptr_type, "array");
 427   tree body = build2 (MODIFY_EXPR, array_ptr_type, tmp,
 428                       build_new_array (element_type, length));
 429
 430   int index = 0;
 431
 432   /* FIXME: try to allocate array statically?  */
 433   FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), cnt, value)
 434     {
 435       /* FIXME: Should use build_java_arrayaccess here, but avoid
 436          bounds checking.  */
 437       tree lhs = build3 (COMPONENT_REF, TREE_TYPE (data_field),
 438                          build_java_indirect_ref (array_type, tmp, 0),
 439                          data_field, NULL_TREE);
 440       tree assignment = build2 (MODIFY_EXPR, element_type,
 441                                 build4 (ARRAY_REF, element_type, lhs,
 442                                         build_int_cst (NULL_TREE, index++),
 443                                         NULL_TREE, NULL_TREE),
 444                                 value);
 445       body = build2 (COMPOUND_EXPR, element_type, body, assignment);
 446     }
 447
 448   return build2 (COMPOUND_EXPR, array_ptr_type, body, tmp);
 449 }
 450
 451 static tree
 452 java_gimplify_try_expr (tree try_expr)
 453 {
 454   tree body = TREE_OPERAND (try_expr, 0);
 455   tree handler = TREE_OPERAND (try_expr, 1);
 456   tree catch = NULL_TREE;
 457
 458   /* Build a CATCH_EXPR for each handler.  */
 459   while (handler)
 460     {
 461       tree java_catch = TREE_OPERAND (handler, 0);
 462       tree catch_type = TREE_TYPE (TREE_TYPE (BLOCK_EXPR_DECLS (java_catch)));
 463       tree expr = build2 (CATCH_EXPR, void_type_node,
 464                           prepare_eh_table_type (catch_type),
 465                           handler);
 466       if (catch)
 467         catch = build2 (COMPOUND_EXPR, void_type_node, catch, expr);
 468       else
 469         catch = expr;
 470       handler = TREE_CHAIN (handler);
 471     }
 472   return build2 (TRY_CATCH_EXPR, void_type_node, body, catch);
 473 }
 474
 475 /* Dump a tree of some kind.  This is a convenience wrapper for the
 476    dump_* functions in tree-dump.c.  */
 477 static void
 478 dump_java_tree (enum tree_dump_index phase, tree t)
 479 {
 480   FILE *stream;
 481   int flags;
 482
 483   stream = dump_begin (phase, &flags);
 484   flags |= TDF_SLIM;
 485   if (stream)
 486     {
 487       dump_node (t, flags, stream);
 488       dump_end (phase, stream);
 489     }
 490 }