2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
4 * Copyright (c) 2000 by Hewlett-Packard Company. All rights reserved.
6 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
7 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
9 * Permission is hereby granted to use or copy this program
10 * for any purpose, provided the above notices are retained on all copies.
11 * Permission to modify the code and to distribute modified code is granted,
12 * provided the above notices are retained, and a notice that the code was
13 * modified is included with the above copyright notice.
15 * This file contains the functions:
16 * ptr_t GC_build_flXXX(h, old_fl)
17 * void GC_new_hblk(size)
19 /* Boehm, May 19, 1994 2:09 pm PDT */
23 # include "private/gc_priv.h"
27 * Build a free list for size 2 (words) cleared objects inside hblk h.
28 * Set the last link to
29 * be ofl. Return a pointer tpo the first free list entry.
31 STATIC ptr_t GC_build_fl_clear2(struct hblk *h, ptr_t ofl)
33 word * p = (word *)(h -> hb_body);
34 word * lim = (word *)(h + 1);
41 for (; p < lim; p += 4) {
50 /* The same for size 4 cleared objects */
51 STATIC ptr_t GC_build_fl_clear4(struct hblk *h, ptr_t ofl)
53 word * p = (word *)(h -> hb_body);
54 word * lim = (word *)(h + 1);
61 for (; p < lim; p += 4) {
62 PREFETCH_FOR_WRITE((ptr_t)(p+64));
70 /* The same for size 2 uncleared objects */
71 STATIC ptr_t GC_build_fl2(struct hblk *h, ptr_t ofl)
73 word * p = (word *)(h -> hb_body);
74 word * lim = (word *)(h + 1);
79 for (; p < lim; p += 4) {
86 /* The same for size 4 uncleared objects */
87 STATIC ptr_t GC_build_fl4(struct hblk *h, ptr_t ofl)
89 word * p = (word *)(h -> hb_body);
90 word * lim = (word *)(h + 1);
95 for (; p < lim; p += 8) {
96 PREFETCH_FOR_WRITE((ptr_t)(p+64));
100 return((ptr_t)(p-4));
103 #endif /* !SMALL_CONFIG */
106 /* Build a free list for objects of size sz inside heap block h. */
107 /* Clear objects inside h if clear is set. Add list to the end of */
108 /* the free list we build. Return the new free list. */
109 /* This could be called without the main GC lock, if we ensure that */
110 /* there is no concurrent collection which might reclaim objects that */
111 /* we have not yet allocated. */
112 ptr_t GC_build_fl(struct hblk *h, size_t sz, GC_bool clear, ptr_t list)
115 word *last_object; /* points to last object in new hblk */
117 /* Do a few prefetches here, just because its cheap. */
118 /* If we were more serious about it, these should go inside */
119 /* the loops. But write prefetches usually don't seem to */
121 PREFETCH_FOR_WRITE((ptr_t)h);
122 PREFETCH_FOR_WRITE((ptr_t)h + 128);
123 PREFETCH_FOR_WRITE((ptr_t)h + 256);
124 PREFETCH_FOR_WRITE((ptr_t)h + 378);
125 /* Handle small objects sizes more efficiently. For larger objects */
126 /* the difference is less significant. */
127 # ifndef SMALL_CONFIG
130 return GC_build_fl_clear2(h, list);
132 return GC_build_fl2(h, list);
135 return GC_build_fl_clear4(h, list);
137 return GC_build_fl4(h, list);
142 # endif /* !SMALL_CONFIG */
144 /* Clear the page if necessary. */
145 if (clear) BZERO(h, HBLKSIZE);
147 /* Add objects to free list */
148 p = (word *)(h -> hb_body) + sz; /* second object in *h */
149 prev = (word *)(h -> hb_body); /* One object behind p */
150 last_object = (word *)((char *)h + HBLKSIZE);
152 /* Last place for last object to start */
154 /* make a list of all objects in *h with head as last object */
155 while (p <= last_object) {
156 /* current object's link points to last object */
157 obj_link(p) = (ptr_t)prev;
161 p -= sz; /* p now points to last object */
164 * put p (which is now head of list of objects in *h) as first
165 * pointer in the appropriate free list for this size.
167 obj_link(h -> hb_body) = list;
173 * Allocate a new heapblock for small objects of size gran granules.
174 * Add all of the heapblock's objects to the free list for objects
176 * Set all mark bits if objects are uncollectable.
177 * Will fail to do anything if we are out of memory.
179 void GC_new_hblk(size_t gran, int kind)
181 struct hblk *h; /* the new heap block */
182 GC_bool clear = GC_obj_kinds[kind].ok_init;
184 GC_STATIC_ASSERT((sizeof (struct hblk)) == HBLKSIZE);
186 if (GC_debugging_started) clear = TRUE;
188 /* Allocate a new heap block */
189 h = GC_allochblk(GRANULES_TO_BYTES(gran), kind, 0);
192 /* Mark all objects if appropriate. */
193 if (IS_UNCOLLECTABLE(kind)) GC_set_hdr_marks(HDR(h));
195 /* Build the free list */
196 GC_obj_kinds[kind].ok_freelist[gran] =
197 GC_build_fl(h, GRANULES_TO_WORDS(gran), clear,
198 GC_obj_kinds[kind].ok_freelist[gran]);