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new_hblk.c
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new_hblk.c
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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 2000 by Hewlett-Packard Company. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/gc_priv.h"
/*
* This file contains the functions:
* ptr_t GC_build_flXXX(h, old_fl)
* void GC_new_hblk(size, kind)
*/
#ifndef SMALL_CONFIG
/* Build a free list for two-pointer cleared objects inside the given */
/* block. Set the last link to be ofl. Return a pointer to the */
/* first free-list entry. */
STATIC ptr_t GC_build_fl_clear2(struct hblk *h, ptr_t ofl)
{
ptr_t *p = (ptr_t *)(h -> hb_body);
ptr_t plim = (ptr_t)(h + 1);
p[0] = ofl;
p[1] = NULL;
p[2] = (ptr_t)p;
p[3] = NULL;
for (p += 4; ADDR_LT((ptr_t)p, plim); p += 4) {
p[0] = (ptr_t)(p - 2);
p[1] = NULL;
p[2] = (ptr_t)p;
p[3] = NULL;
}
return (ptr_t)(p - 2);
}
/* The same as above but uncleared objects. */
STATIC ptr_t GC_build_fl2(struct hblk *h, ptr_t ofl)
{
ptr_t *p = (ptr_t *)(h -> hb_body);
ptr_t plim = (ptr_t)(h + 1);
p[0] = ofl;
p[2] = (ptr_t)p;
for (p += 4; ADDR_LT((ptr_t)p, plim); p += 4) {
p[0] = (ptr_t)(p - 2);
p[2] = (ptr_t)p;
}
return (ptr_t)(p - 2);
}
/* The same as above but for four-pointer cleared objects. */
STATIC ptr_t GC_build_fl_clear4(struct hblk *h, ptr_t ofl)
{
ptr_t *p = (ptr_t *)(h -> hb_body);
ptr_t plim = (ptr_t)(h + 1);
p[0] = ofl;
p[1] = NULL;
p[2] = NULL;
p[3] = NULL;
for (p += 4; ADDR_LT((ptr_t)p, plim); p += 4) {
GC_PREFETCH_FOR_WRITE((ptr_t)(p + 64));
p[0] = (ptr_t)(p - 4);
p[1] = NULL;
CLEAR_DOUBLE(p + 2);
}
return (ptr_t)(p - 4);
}
/* The same as GC_build_fl_clear4() but uncleared objects. */
STATIC ptr_t GC_build_fl4(struct hblk *h, ptr_t ofl)
{
ptr_t *p = (ptr_t *)(h -> hb_body);
ptr_t plim = (ptr_t)(h + 1);
p[0] = ofl;
p[4] = (ptr_t)p;
for (p += 8; ADDR_LT((ptr_t)p, plim); p += 8) { /* unroll by 2 */
GC_PREFETCH_FOR_WRITE((ptr_t)(p + 64));
p[0] = (ptr_t)(p - 4);
p[4] = (ptr_t)p;
}
return (ptr_t)(p - 4);
}
#endif /* !SMALL_CONFIG */
GC_INNER ptr_t GC_build_fl(struct hblk *h, ptr_t list, size_t lg,
GC_bool clear)
{
ptr_t *p, *prev;
ptr_t plim; /* points to last object in new hblk */
size_t lpw = GRANULES_TO_PTRS(lg);
/* Do a few prefetches here, just because it's cheap. */
/* If we were more serious about it, these should go inside */
/* the loops. But write prefetches usually don't seem to */
/* matter much. */
GC_PREFETCH_FOR_WRITE((ptr_t)h);
GC_PREFETCH_FOR_WRITE((ptr_t)h + 128);
GC_PREFETCH_FOR_WRITE((ptr_t)h + 256);
GC_PREFETCH_FOR_WRITE((ptr_t)h + 378);
# ifndef SMALL_CONFIG
/* Handle small objects sizes more efficiently. For larger objects */
/* the difference is less significant. */
switch (lpw) {
case 2:
if (clear) {
return GC_build_fl_clear2(h, list);
} else {
return GC_build_fl2(h, list);
}
case 4:
if (clear) {
return GC_build_fl_clear4(h, list);
} else {
return GC_build_fl4(h, list);
}
default:
break;
}
# endif /* !SMALL_CONFIG */
/* Clear the page if necessary. */
if (clear) BZERO(h, HBLKSIZE);
/* Add objects to free list. */
prev = (ptr_t *)(h -> hb_body); /* one object behind p */
plim = (ptr_t)h + HBLKSIZE - lpw * sizeof(ptr_t);
/* last place for last object to start */
/* Make a list of all objects in *h with head as last object. */
for (p = prev + lpw; ADDR_GE(plim, (ptr_t)p); p += lpw) {
/* current object's link points to last object */
obj_link(p) = (ptr_t)prev;
prev = p;
}
p -= lpw; /* p now points to last object */
/* Put p (which is now head of list of objects in *h) as first */
/* pointer in the appropriate free list for this size. */
*(ptr_t *)h = list;
return (ptr_t)p;
}
GC_INNER void GC_new_hblk(size_t lg, int k)
{
struct hblk *h; /* the new heap block */
size_t lb_adjusted = GRANULES_TO_BYTES(lg);
GC_STATIC_ASSERT(sizeof(struct hblk) == HBLKSIZE);
GC_ASSERT(I_HOLD_LOCK());
/* Allocate a new heap block. */
h = GC_allochblk(lb_adjusted, k, 0 /* flags */, 0 /* align_m1 */);
if (EXPECT(NULL == h, FALSE)) return; /* out of memory */
/* Mark all objects if appropriate. */
if (IS_UNCOLLECTABLE(k)) GC_set_hdr_marks(HDR(h));
/* Build the free list. */
GC_obj_kinds[k].ok_freelist[lg] =
GC_build_fl(h, (ptr_t)GC_obj_kinds[k].ok_freelist[lg], lg,
GC_debugging_started || GC_obj_kinds[k].ok_init);
}