1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright (c) 1987 Sun Microsystems, Inc.
24 */
25
26#ident	"%Z%%M%	%I%	%E% SMI"
27
28	.file	"alloca.s"
29
30#include <sys/asm_linkage.h>
31
32	!
33	! o0: # bytes of space to allocate, already rounded to 0 mod 8
34	! o1: %sp-relative offset of tmp area
35	! o2: %sp-relative offset of end of tmp area
36	!
37	! we want to bump %sp by the requested size
38	! then copy the tmp area to its new home
39	! this is necessasy as we could theoretically
40	! be in the middle of a compilicated expression.
41	!
42	ENTRY(__builtin_alloca)
43	mov	%sp, %o3		! save current sp
44	sub	%sp, %o0, %sp		! bump to new value
45	! copy loop: should do nothing gracefully
46	b	2f
47	subcc	%o2, %o1, %o5		! number of bytes to move
481:
49	ld	[%o3 + %o1], %o4	! load from old temp area
50	st	%o4, [%sp + %o1]	! store to new temp area
51	add	%o1, 4, %o1
522:	bg	1b
53	subcc	%o5, 4, %o5
54	! now return new %sp + end-of-temp
55	retl
56	add	%sp, %o2, %o0
57
58	SET_SIZE(__builtin_alloca)
59