xref: /illumos-gate/usr/src/lib/libc/amd64/gen/alloca.S (revision ddb365bfc9e868ad24ccdcb0dc91af18b10df082)
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 (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26	.file	"alloca.s"
27
28#include "SYS.h"
29
30	ENTRY(__builtin_alloca)
31	popq	%rcx			/* grab our return address */
32	addq	$15, %rdi		/* round size up to multiple of 16 */
33	andq	$0xfffffffffffffff0, %rdi
34	subq	%rdi, %rsp		/* allocate requested space on stack */
35	movq	%rsp, %rax		/* pointer to new memory block */
36	jmp	*%rcx			/* return */
37	SET_SIZE(__builtin_alloca)
38