/* Functions related to the Boehm garbage collector.
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/* Functions related to the Boehm garbage collector.
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Copyright (C) 2000, 2003, 2004, 2006, 2009, 2010
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Copyright (C) 2000, 2003, 2004, 2006, 2009, 2010
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Free Software Foundation, Inc.
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Free Software Foundation, Inc.
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This file is part of GCC.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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any later version.
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GCC is distributed in the hope that it will be useful,
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>.
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<http://www.gnu.org/licenses/>.
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Java and all Java-based marks are trademarks or registered trademarks
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Java and all Java-based marks are trademarks or registered trademarks
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of Sun Microsystems, Inc. in the United States and other countries.
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of Sun Microsystems, Inc. in the United States and other countries.
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The Free Software Foundation is independent of Sun Microsystems, Inc. */
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The Free Software Foundation is independent of Sun Microsystems, Inc. */
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/* Written by Tom Tromey <tromey@cygnus.com>. */
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/* Written by Tom Tromey <tromey@cygnus.com>. */
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#include "config.h"
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#include "config.h"
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#include "system.h"
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#include "system.h"
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#include "coretypes.h"
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#include "coretypes.h"
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#include "double-int.h"
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#include "double-int.h"
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#include "tm.h"
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#include "tm.h"
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#include "tree.h"
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#include "tree.h"
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#include "java-tree.h"
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#include "java-tree.h"
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#include "parse.h"
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#include "parse.h"
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#include "diagnostic-core.h"
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#include "diagnostic-core.h"
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static void mark_reference_fields (tree, double_int *, unsigned int,
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static void mark_reference_fields (tree, double_int *, unsigned int,
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int *, int *, int *, HOST_WIDE_INT *);
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int *, int *, int *, HOST_WIDE_INT *);
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/* A procedure-based object descriptor. We know that our
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/* A procedure-based object descriptor. We know that our
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`kind' is 0, and `env' is likewise 0, so we have a simple
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`kind' is 0, and `env' is likewise 0, so we have a simple
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computation. From the GC sources:
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computation. From the GC sources:
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(((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \
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(((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \
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| DS_PROC)
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| DS_PROC)
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Here DS_PROC == 2. */
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Here DS_PROC == 2. */
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#define PROCEDURE_OBJECT_DESCRIPTOR 2
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#define PROCEDURE_OBJECT_DESCRIPTOR 2
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/* Recursively mark reference fields. */
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/* Recursively mark reference fields. */
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static void
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static void
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mark_reference_fields (tree field,
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mark_reference_fields (tree field,
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double_int *mask,
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double_int *mask,
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unsigned int ubit,
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unsigned int ubit,
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int *pointer_after_end,
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int *pointer_after_end,
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int *all_bits_set,
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int *all_bits_set,
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int *last_set_index,
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int *last_set_index,
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HOST_WIDE_INT *last_view_index)
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HOST_WIDE_INT *last_view_index)
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{
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{
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/* See if we have fields from our superclass. */
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/* See if we have fields from our superclass. */
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if (DECL_NAME (field) == NULL_TREE)
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if (DECL_NAME (field) == NULL_TREE)
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{
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{
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mark_reference_fields (TYPE_FIELDS (TREE_TYPE (field)),
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mark_reference_fields (TYPE_FIELDS (TREE_TYPE (field)),
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mask, ubit,
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mask, ubit,
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pointer_after_end, all_bits_set,
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pointer_after_end, all_bits_set,
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last_set_index, last_view_index);
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last_set_index, last_view_index);
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field = DECL_CHAIN (field);
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field = DECL_CHAIN (field);
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}
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}
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for (; field != NULL_TREE; field = DECL_CHAIN (field))
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for (; field != NULL_TREE; field = DECL_CHAIN (field))
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{
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{
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HOST_WIDE_INT offset;
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HOST_WIDE_INT offset;
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HOST_WIDE_INT size_bytes;
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HOST_WIDE_INT size_bytes;
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if (FIELD_STATIC (field))
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if (FIELD_STATIC (field))
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continue;
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continue;
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offset = int_byte_position (field);
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offset = int_byte_position (field);
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size_bytes = int_size_in_bytes (TREE_TYPE (field));
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size_bytes = int_size_in_bytes (TREE_TYPE (field));
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if (JREFERENCE_TYPE_P (TREE_TYPE (field))
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if (JREFERENCE_TYPE_P (TREE_TYPE (field))
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/* An `object' of type gnu.gcj.RawData is actually non-Java
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/* An `object' of type gnu.gcj.RawData is actually non-Java
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data. */
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data. */
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&& TREE_TYPE (field) != rawdata_ptr_type_node)
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&& TREE_TYPE (field) != rawdata_ptr_type_node)
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{
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{
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unsigned int count;
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unsigned int count;
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unsigned int size_words;
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unsigned int size_words;
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unsigned int i;
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unsigned int i;
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/* If this reference slot appears to overlay a slot we think
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/* If this reference slot appears to overlay a slot we think
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we already covered, then we are doomed. */
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we already covered, then we are doomed. */
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gcc_assert (offset > *last_view_index);
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gcc_assert (offset > *last_view_index);
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if (offset % (HOST_WIDE_INT) (POINTER_SIZE / BITS_PER_UNIT))
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if (offset % (HOST_WIDE_INT) (POINTER_SIZE / BITS_PER_UNIT))
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{
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{
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*all_bits_set = -1;
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*all_bits_set = -1;
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*pointer_after_end = 1;
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*pointer_after_end = 1;
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break;
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break;
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}
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}
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count = offset * BITS_PER_UNIT / POINTER_SIZE;
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count = offset * BITS_PER_UNIT / POINTER_SIZE;
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size_words = size_bytes * BITS_PER_UNIT / POINTER_SIZE;
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size_words = size_bytes * BITS_PER_UNIT / POINTER_SIZE;
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*last_set_index = count;
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*last_set_index = count;
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/* First word in object corresponds to most significant byte of
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/* First word in object corresponds to most significant byte of
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bitmap.
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bitmap.
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In the case of a multiple-word record, we set pointer
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In the case of a multiple-word record, we set pointer
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bits for all words in the record. This is conservative, but the
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bits for all words in the record. This is conservative, but the
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size_words != 1 case is impossible in regular java code. */
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size_words != 1 case is impossible in regular java code. */
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for (i = 0; i < size_words; ++i)
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for (i = 0; i < size_words; ++i)
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*mask = double_int_setbit (*mask, ubit - count - i - 1);
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*mask = double_int_setbit (*mask, ubit - count - i - 1);
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if (count >= ubit - 2)
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if (count >= ubit - 2)
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*pointer_after_end = 1;
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*pointer_after_end = 1;
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/* If we saw a non-reference field earlier, then we can't
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/* If we saw a non-reference field earlier, then we can't
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use the count representation. We keep track of that in
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use the count representation. We keep track of that in
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*ALL_BITS_SET. */
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*ALL_BITS_SET. */
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if (! *all_bits_set)
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if (! *all_bits_set)
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*all_bits_set = -1;
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*all_bits_set = -1;
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}
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}
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else if (*all_bits_set > 0)
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else if (*all_bits_set > 0)
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*all_bits_set = 0;
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*all_bits_set = 0;
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*last_view_index = offset;
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*last_view_index = offset;
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}
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}
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}
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}
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/* Return the marking bitmap for the class TYPE. For now this is a
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/* Return the marking bitmap for the class TYPE. For now this is a
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single word describing the type. */
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single word describing the type. */
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tree
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tree
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get_boehm_type_descriptor (tree type)
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get_boehm_type_descriptor (tree type)
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{
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{
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unsigned int count, log2_size, ubit;
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unsigned int count, log2_size, ubit;
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int bit;
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int bit;
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int all_bits_set = 1;
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int all_bits_set = 1;
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int last_set_index = 0;
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int last_set_index = 0;
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HOST_WIDE_INT last_view_index = -1;
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HOST_WIDE_INT last_view_index = -1;
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int pointer_after_end = 0;
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int pointer_after_end = 0;
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double_int mask;
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double_int mask;
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tree field, value, value_type;
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tree field, value, value_type;
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mask = double_int_zero;
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mask = double_int_zero;
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/* If the GC wasn't requested, just use a null pointer. */
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/* If the GC wasn't requested, just use a null pointer. */
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if (! flag_use_boehm_gc)
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if (! flag_use_boehm_gc)
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return null_pointer_node;
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return null_pointer_node;
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value_type = java_type_for_mode (ptr_mode, 1);
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value_type = java_type_for_mode (ptr_mode, 1);
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/* If we have a type of unknown size, use a proc. */
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/* If we have a type of unknown size, use a proc. */
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if (int_size_in_bytes (type) == -1)
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if (int_size_in_bytes (type) == -1)
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goto procedure_object_descriptor;
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goto procedure_object_descriptor;
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bit = POINTER_SIZE / BITS_PER_UNIT;
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bit = POINTER_SIZE / BITS_PER_UNIT;
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/* The size of this node has to be known. And, we only support 32
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/* The size of this node has to be known. And, we only support 32
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and 64 bit targets, so we need to know that the log2 is one of
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and 64 bit targets, so we need to know that the log2 is one of
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our values. */
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our values. */
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log2_size = exact_log2 (bit);
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log2_size = exact_log2 (bit);
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if (bit == -1 || (log2_size != 2 && log2_size != 3))
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if (bit == -1 || (log2_size != 2 && log2_size != 3))
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{
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{
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/* This means the GC isn't supported. We should probably
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/* This means the GC isn't supported. We should probably
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abort or give an error. Instead, for now, we just silently
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abort or give an error. Instead, for now, we just silently
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revert. FIXME. */
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revert. FIXME. */
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return null_pointer_node;
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return null_pointer_node;
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}
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}
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bit *= BITS_PER_UNIT;
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bit *= BITS_PER_UNIT;
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/* Warning avoidance. */
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/* Warning avoidance. */
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ubit = (unsigned int) bit;
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ubit = (unsigned int) bit;
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if (type == class_type_node)
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if (type == class_type_node)
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goto procedure_object_descriptor;
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goto procedure_object_descriptor;
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field = TYPE_FIELDS (type);
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field = TYPE_FIELDS (type);
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mark_reference_fields (field, &mask, ubit,
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mark_reference_fields (field, &mask, ubit,
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&pointer_after_end, &all_bits_set,
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&pointer_after_end, &all_bits_set,
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&last_set_index, &last_view_index);
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&last_set_index, &last_view_index);
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/* If the object is all pointers, or if the part with pointers fits
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/* If the object is all pointers, or if the part with pointers fits
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in our bitmap, then we are ok. Otherwise we have to allocate it
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in our bitmap, then we are ok. Otherwise we have to allocate it
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a different way. */
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a different way. */
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if (all_bits_set != -1 || (pointer_after_end && flag_reduced_reflection))
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if (all_bits_set != -1 || (pointer_after_end && flag_reduced_reflection))
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{
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{
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/* In this case the initial part of the object is all reference
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/* In this case the initial part of the object is all reference
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fields, and the end of the object is all non-reference
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fields, and the end of the object is all non-reference
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fields. We represent the mark as a count of the fields,
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fields. We represent the mark as a count of the fields,
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shifted. In the GC the computation looks something like
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shifted. In the GC the computation looks something like
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this:
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this:
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value = DS_LENGTH | WORDS_TO_BYTES (last_set_index + 1);
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value = DS_LENGTH | WORDS_TO_BYTES (last_set_index + 1);
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DS_LENGTH is 0.
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DS_LENGTH is 0.
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WORDS_TO_BYTES shifts by log2(bytes-per-pointer).
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WORDS_TO_BYTES shifts by log2(bytes-per-pointer).
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In the case of flag_reduced_reflection and the bitmap would
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In the case of flag_reduced_reflection and the bitmap would
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overflow, we tell the gc that the object is all pointers so
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overflow, we tell the gc that the object is all pointers so
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that we don't have to emit reflection data for run time
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that we don't have to emit reflection data for run time
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marking. */
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marking. */
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count = 0;
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count = 0;
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mask = double_int_zero;
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mask = double_int_zero;
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++last_set_index;
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++last_set_index;
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while (last_set_index)
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while (last_set_index)
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{
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{
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if ((last_set_index & 1))
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if ((last_set_index & 1))
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mask = double_int_setbit (mask, log2_size + count);
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mask = double_int_setbit (mask, log2_size + count);
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last_set_index >>= 1;
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last_set_index >>= 1;
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++count;
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++count;
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}
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}
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value = double_int_to_tree (value_type, mask);
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value = double_int_to_tree (value_type, mask);
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}
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}
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else if (! pointer_after_end)
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else if (! pointer_after_end)
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{
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{
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/* Bottom two bits for bitmap mark type are 01. */
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/* Bottom two bits for bitmap mark type are 01. */
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mask = double_int_setbit (mask, 0);
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mask = double_int_setbit (mask, 0);
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value = double_int_to_tree (value_type, mask);
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value = double_int_to_tree (value_type, mask);
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}
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}
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else
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else
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{
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{
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procedure_object_descriptor:
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procedure_object_descriptor:
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value = build_int_cst (value_type, PROCEDURE_OBJECT_DESCRIPTOR);
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value = build_int_cst (value_type, PROCEDURE_OBJECT_DESCRIPTOR);
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}
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}
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return value;
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return value;
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}
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}
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/* The fourth (index of 3) element in the vtable is the GC descriptor.
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/* The fourth (index of 3) element in the vtable is the GC descriptor.
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A value of 2 indicates that the class uses _Jv_MarkObj. */
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A value of 2 indicates that the class uses _Jv_MarkObj. */
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bool
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bool
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uses_jv_markobj_p (tree dtable)
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uses_jv_markobj_p (tree dtable)
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{
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{
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tree v;
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tree v;
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/* FIXME: what do we return if !flag_use_boehm_gc ? */
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/* FIXME: what do we return if !flag_use_boehm_gc ? */
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gcc_assert (flag_use_boehm_gc);
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gcc_assert (flag_use_boehm_gc);
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/* FIXME: this is wrong if TARGET_VTABLE_USES_DESCRIPTORS. However,
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/* FIXME: this is wrong if TARGET_VTABLE_USES_DESCRIPTORS. However,
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this function is only used with flag_reduced_reflection. No
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this function is only used with flag_reduced_reflection. No
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point in asserting unless we hit the bad case. */
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point in asserting unless we hit the bad case. */
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gcc_assert (!flag_reduced_reflection || TARGET_VTABLE_USES_DESCRIPTORS == 0);
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gcc_assert (!flag_reduced_reflection || TARGET_VTABLE_USES_DESCRIPTORS == 0);
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v = VEC_index (constructor_elt, CONSTRUCTOR_ELTS (dtable), 3)->value;
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v = VEC_index (constructor_elt, CONSTRUCTOR_ELTS (dtable), 3)->value;
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return (PROCEDURE_OBJECT_DESCRIPTOR == TREE_INT_CST_LOW (v));
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return (PROCEDURE_OBJECT_DESCRIPTOR == TREE_INT_CST_LOW (v));
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}
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}
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