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PATCH: obstack: first object of each chunk not aligned
- To: libc-alpha at sourceware dot cygnus dot com
- Subject: PATCH: obstack: first object of each chunk not aligned
- From: Alexandre Duret-Lutz <duret_g at lrde dot epita dot fr>
- Date: 23 Oct 2000 18:52:27 +0200
- Organization: LRDE/EPITA http://www.lrde.epita.fr/
As a followup to my bug report, would this be ok ?
Index: ChangeLog
from Alexandre Duret-Lutz <duret_g@epita.fr>
* malloc/obstack.c (_obstack_newchunk): Use alignment_mask to
align the first object in a new chunk.
Index: malloc/obstack.c
===================================================================
RCS file: /cvs/glibc/libc/malloc/obstack.c,v
retrieving revision 1.10
diff -u -r1.10 obstack.c
--- obstack.c 2000/10/16 16:16:29 1.10
+++ obstack.c 2000/10/23 16:38:29
@@ -282,9 +282,10 @@
register long obj_size = h->next_free - h->object_base;
register long i;
long already;
+ char *object_base;
/* Compute size for new chunk. */
- new_size = (obj_size + length) + (obj_size >> 3) + 100;
+ new_size = (obj_size + length) + (obj_size >> 3) + h->alignment_mask + 100;
if (new_size < h->chunk_size)
new_size = h->chunk_size;
@@ -296,6 +297,11 @@
new_chunk->prev = old_chunk;
new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
+ /* Compute an aligned object_base in the new chunk */
+ object_base =
+ __INT_TO_PTR ((__PTR_TO_INT (new_chunk->contents) + h->alignment_mask)
+ & ~ (h->alignment_mask));
+
/* Move the existing object to the new chunk.
Word at a time is fast and is safe if the object
is sufficiently aligned. */
@@ -303,7 +309,7 @@
{
for (i = obj_size / sizeof (COPYING_UNIT) - 1;
i >= 0; i--)
- ((COPYING_UNIT *)new_chunk->contents)[i]
+ ((COPYING_UNIT *)object_base)[i]
= ((COPYING_UNIT *)h->object_base)[i];
/* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
but that can cross a page boundary on a machine
@@ -314,7 +320,7 @@
already = 0;
/* Copy remaining bytes one by one. */
for (i = already; i < obj_size; i++)
- new_chunk->contents[i] = h->object_base[i];
+ object_base[i] = h->object_base[i];
/* If the object just copied was the only data in OLD_CHUNK,
free that chunk and remove it from the chain.
@@ -325,7 +331,7 @@
CALL_FREEFUN (h, old_chunk);
}
- h->object_base = new_chunk->contents;
+ h->object_base = object_base;
h->next_free = h->object_base + obj_size;
/* The new chunk certainly contains no empty object yet. */
h->maybe_empty_object = 0;
--
Alexandre Duret-Lutz