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5830574a | 1 | /* Functions related to the Boehm garbage collector. |
f309ff0a | 2 | Copyright (C) 2000, 2003 Free Software Foundation, Inc. |
5830574a | 3 | |
f309ff0a | 4 | This file is part of GCC. |
5830574a | 5 | |
f309ff0a | 6 | GCC is free software; you can redistribute it and/or modify |
5830574a TT |
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 | ||
f309ff0a | 11 | GCC is distributed in the hope that it will be useful, |
5830574a TT |
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 | |
f309ff0a | 17 | along with GCC; see the file COPYING. If not, write to |
5830574a TT |
18 | the Free Software Foundation, 59 Temple Place - Suite 330, |
19 | Boston, MA 02111-1307, 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 | /* Written by Tom Tromey <tromey@cygnus.com>. */ | |
26 | ||
27 | #include <config.h> | |
28 | ||
29 | #include "system.h" | |
4977bab6 ZW |
30 | #include "coretypes.h" |
31 | #include "tm.h" | |
5830574a TT |
32 | #include "tree.h" |
33 | #include "java-tree.h" | |
34 | #include "parse.h" | |
d6684bc8 | 35 | #include "toplev.h" |
5830574a | 36 | |
d2097937 KG |
37 | static void mark_reference_fields (tree, unsigned HOST_WIDE_INT *, |
38 | unsigned HOST_WIDE_INT *, unsigned int, | |
39 | int *, int *, int *, HOST_WIDE_INT *); | |
40 | static void set_bit (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, | |
41 | unsigned int); | |
c0b864fc | 42 | |
5830574a TT |
43 | /* Treat two HOST_WIDE_INT's as a contiguous bitmap, with bit 0 being |
44 | the least significant. This function sets bit N in the bitmap. */ | |
45 | static void | |
0a2f0c54 KG |
46 | set_bit (unsigned HOST_WIDE_INT *low, unsigned HOST_WIDE_INT *high, |
47 | unsigned int n) | |
5830574a | 48 | { |
0e7d217a | 49 | unsigned HOST_WIDE_INT *which; |
5830574a TT |
50 | |
51 | if (n >= HOST_BITS_PER_WIDE_INT) | |
52 | { | |
53 | n -= HOST_BITS_PER_WIDE_INT; | |
54 | which = high; | |
55 | } | |
56 | else | |
57 | which = low; | |
58 | ||
0e7d217a | 59 | *which |= (unsigned HOST_WIDE_INT) 1 << n; |
5830574a TT |
60 | } |
61 | ||
2c6c322a | 62 | /* Recursively mark reference fields. */ |
d5f76aba | 63 | static void |
0a2f0c54 KG |
64 | mark_reference_fields (tree field, |
65 | unsigned HOST_WIDE_INT *low, | |
66 | unsigned HOST_WIDE_INT *high, | |
67 | unsigned int ubit, | |
68 | int *pointer_after_end, | |
69 | int *all_bits_set, | |
70 | int *last_set_index, | |
71 | HOST_WIDE_INT *last_view_index) | |
2c6c322a | 72 | { |
2c6c322a TT |
73 | /* See if we have fields from our superclass. */ |
74 | if (DECL_NAME (field) == NULL_TREE) | |
75 | { | |
d5f76aba TT |
76 | mark_reference_fields (TYPE_FIELDS (TREE_TYPE (field)), |
77 | low, high, ubit, | |
78 | pointer_after_end, all_bits_set, | |
79 | last_set_index, last_view_index); | |
2c6c322a TT |
80 | field = TREE_CHAIN (field); |
81 | } | |
82 | ||
83 | for (; field != NULL_TREE; field = TREE_CHAIN (field)) | |
84 | { | |
8a008c41 | 85 | HOST_WIDE_INT offset; |
7c097ee9 | 86 | HOST_WIDE_INT size_bytes; |
d5f76aba | 87 | |
2c6c322a TT |
88 | if (FIELD_STATIC (field)) |
89 | continue; | |
90 | ||
3c8c10b8 | 91 | offset = int_byte_position (field); |
7c097ee9 | 92 | size_bytes = int_size_in_bytes (TREE_TYPE (field)); |
652f2504 TT |
93 | if (JREFERENCE_TYPE_P (TREE_TYPE (field)) |
94 | /* An `object' of type gnu.gcj.RawData is actually non-Java | |
95 | data. */ | |
96 | && TREE_TYPE (field) != rawdata_ptr_type_node) | |
2c6c322a | 97 | { |
d5f76aba | 98 | unsigned int count; |
7c097ee9 HB |
99 | unsigned int size_words; |
100 | unsigned int i; | |
d5f76aba TT |
101 | |
102 | /* If this reference slot appears to overlay a slot we think | |
103 | we already covered, then we are doomed. */ | |
104 | if (offset <= *last_view_index) | |
105 | abort (); | |
106 | ||
107 | count = offset * BITS_PER_UNIT / POINTER_SIZE; | |
7c097ee9 | 108 | size_words = size_bytes * BITS_PER_UNIT / POINTER_SIZE; |
d5f76aba | 109 | |
2c6c322a | 110 | *last_set_index = count; |
7c097ee9 HB |
111 | |
112 | /* First word in object corresponds to most significant byte of | |
113 | bitmap. | |
114 | ||
115 | In the case of a multiple-word record, we set pointer | |
116 | bits for all words in the record. This is conservative, but the | |
117 | size_words != 1 case is impossible in regular java code. */ | |
118 | for (i = 0; i < size_words; ++i) | |
119 | set_bit (low, high, ubit - count - i - 1); | |
120 | ||
e35990c4 | 121 | if (count >= ubit - 2) |
2c6c322a | 122 | *pointer_after_end = 1; |
652f2504 TT |
123 | |
124 | /* If we saw a non-reference field earlier, then we can't | |
125 | use the count representation. We keep track of that in | |
126 | *ALL_BITS_SET. */ | |
127 | if (! *all_bits_set) | |
128 | *all_bits_set = -1; | |
2c6c322a | 129 | } |
652f2504 | 130 | else if (*all_bits_set > 0) |
2c6c322a TT |
131 | *all_bits_set = 0; |
132 | ||
d5f76aba | 133 | *last_view_index = offset; |
2c6c322a | 134 | } |
2c6c322a TT |
135 | } |
136 | ||
5830574a TT |
137 | /* Return the marking bitmap for the class TYPE. For now this is a |
138 | single word describing the type. */ | |
139 | tree | |
140 | get_boehm_type_descriptor (tree type) | |
141 | { | |
142 | unsigned int count, log2_size, ubit; | |
143 | int bit; | |
144 | int all_bits_set = 1; | |
145 | int last_set_index = 0; | |
d5f76aba | 146 | HOST_WIDE_INT last_view_index = -1; |
5830574a TT |
147 | int pointer_after_end = 0; |
148 | unsigned HOST_WIDE_INT low = 0, high = 0; | |
149 | tree field, value; | |
150 | ||
151 | /* If the GC wasn't requested, just use a null pointer. */ | |
152 | if (! flag_use_boehm_gc) | |
153 | return null_pointer_node; | |
154 | ||
155 | /* If we have a type of unknown size, use a proc. */ | |
156 | if (int_size_in_bytes (type) == -1) | |
9a07cfaf | 157 | goto procedure_object_descriptor; |
5830574a | 158 | |
2c6c322a | 159 | bit = POINTER_SIZE / BITS_PER_UNIT; |
5830574a TT |
160 | /* The size of this node has to be known. And, we only support 32 |
161 | and 64 bit targets, so we need to know that the log2 is one of | |
162 | our values. */ | |
163 | log2_size = exact_log2 (bit); | |
164 | if (bit == -1 || (log2_size != 2 && log2_size != 3)) | |
165 | { | |
166 | /* This means the GC isn't supported. We should probably | |
167 | abort or give an error. Instead, for now, we just silently | |
168 | revert. FIXME. */ | |
169 | return null_pointer_node; | |
170 | } | |
171 | bit *= BITS_PER_UNIT; | |
172 | ||
173 | /* Warning avoidance. */ | |
174 | ubit = (unsigned int) bit; | |
175 | ||
7c097ee9 | 176 | if (type == class_type_node) |
9a07cfaf | 177 | goto procedure_object_descriptor; |
7c097ee9 | 178 | |
5830574a | 179 | field = TYPE_FIELDS (type); |
d5f76aba TT |
180 | mark_reference_fields (field, &low, &high, ubit, |
181 | &pointer_after_end, &all_bits_set, | |
182 | &last_set_index, &last_view_index); | |
5830574a TT |
183 | |
184 | /* If the object is all pointers, or if the part with pointers fits | |
185 | in our bitmap, then we are ok. Otherwise we have to allocate it | |
186 | a different way. */ | |
652f2504 | 187 | if (all_bits_set != -1) |
5830574a | 188 | { |
652f2504 TT |
189 | /* In this case the initial part of the object is all reference |
190 | fields, and the end of the object is all non-reference | |
191 | fields. We represent the mark as a count of the fields, | |
192 | shifted. In the GC the computation looks something like | |
193 | this: | |
5830574a TT |
194 | value = DS_LENGTH | WORDS_TO_BYTES (last_set_index + 1); |
195 | DS_LENGTH is 0. | |
196 | WORDS_TO_BYTES shifts by log2(bytes-per-pointer). */ | |
197 | count = 0; | |
2c6c322a TT |
198 | low = 0; |
199 | high = 0; | |
5830574a TT |
200 | ++last_set_index; |
201 | while (last_set_index) | |
202 | { | |
203 | if ((last_set_index & 1)) | |
204 | set_bit (&low, &high, log2_size + count); | |
205 | last_set_index >>= 1; | |
206 | ++count; | |
207 | } | |
208 | value = build_int_2 (low, high); | |
209 | } | |
210 | else if (! pointer_after_end) | |
211 | { | |
212 | /* Bottom two bits for bitmap mark type are 01. */ | |
213 | set_bit (&low, &high, 0); | |
214 | value = build_int_2 (low, high); | |
215 | } | |
216 | else | |
9a07cfaf RH |
217 | { |
218 | /* Compute a procedure-based object descriptor. We know that our | |
219 | `kind' is 0, and `env' is likewise 0, so we have a simple | |
220 | computation. From the GC sources: | |
221 | (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \ | |
222 | | DS_PROC) | |
223 | Here DS_PROC == 2. */ | |
224 | procedure_object_descriptor: | |
225 | value = build_int_2 (2, 0); | |
226 | } | |
5830574a | 227 | |
b0c48229 | 228 | TREE_TYPE (value) = java_type_for_mode (ptr_mode, 1); |
5830574a TT |
229 | return value; |
230 | } |