xref: /titanic_51/usr/src/lib/libc/sparc/gen/alloca.s (revision 7c478bd95313f5f23a4c958a745db2134aa03244)
1*7c478bd9Sstevel@tonic-gate/*
2*7c478bd9Sstevel@tonic-gate * CDDL HEADER START
3*7c478bd9Sstevel@tonic-gate *
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7*7c478bd9Sstevel@tonic-gate * with the License.
8*7c478bd9Sstevel@tonic-gate *
9*7c478bd9Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*7c478bd9Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing.
11*7c478bd9Sstevel@tonic-gate * See the License for the specific language governing permissions
12*7c478bd9Sstevel@tonic-gate * and limitations under the License.
13*7c478bd9Sstevel@tonic-gate *
14*7c478bd9Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each
15*7c478bd9Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*7c478bd9Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the
17*7c478bd9Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying
18*7c478bd9Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner]
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20*7c478bd9Sstevel@tonic-gate * CDDL HEADER END
21*7c478bd9Sstevel@tonic-gate */
22*7c478bd9Sstevel@tonic-gate/*
23*7c478bd9Sstevel@tonic-gate * Copyright (c) 1987 Sun Microsystems, Inc.
24*7c478bd9Sstevel@tonic-gate */
25*7c478bd9Sstevel@tonic-gate
26*7c478bd9Sstevel@tonic-gate#ident	"%Z%%M%	%I%	%E% SMI"
27*7c478bd9Sstevel@tonic-gate
28*7c478bd9Sstevel@tonic-gate	.file	"alloca.s"
29*7c478bd9Sstevel@tonic-gate
30*7c478bd9Sstevel@tonic-gate#include <sys/asm_linkage.h>
31*7c478bd9Sstevel@tonic-gate
32*7c478bd9Sstevel@tonic-gate	!
33*7c478bd9Sstevel@tonic-gate	! o0: # bytes of space to allocate, already rounded to 0 mod 8
34*7c478bd9Sstevel@tonic-gate	! o1: %sp-relative offset of tmp area
35*7c478bd9Sstevel@tonic-gate	! o2: %sp-relative offset of end of tmp area
36*7c478bd9Sstevel@tonic-gate	!
37*7c478bd9Sstevel@tonic-gate	! we want to bump %sp by the requested size
38*7c478bd9Sstevel@tonic-gate	! then copy the tmp area to its new home
39*7c478bd9Sstevel@tonic-gate	! this is necessasy as we could theoretically
40*7c478bd9Sstevel@tonic-gate	! be in the middle of a compilicated expression.
41*7c478bd9Sstevel@tonic-gate	!
42*7c478bd9Sstevel@tonic-gate	ENTRY(__builtin_alloca)
43*7c478bd9Sstevel@tonic-gate	mov	%sp, %o3		! save current sp
44*7c478bd9Sstevel@tonic-gate	sub	%sp, %o0, %sp		! bump to new value
45*7c478bd9Sstevel@tonic-gate	! copy loop: should do nothing gracefully
46*7c478bd9Sstevel@tonic-gate	b	2f
47*7c478bd9Sstevel@tonic-gate	subcc	%o2, %o1, %o5		! number of bytes to move
48*7c478bd9Sstevel@tonic-gate1:
49*7c478bd9Sstevel@tonic-gate	ld	[%o3 + %o1], %o4	! load from old temp area
50*7c478bd9Sstevel@tonic-gate	st	%o4, [%sp + %o1]	! store to new temp area
51*7c478bd9Sstevel@tonic-gate	add	%o1, 4, %o1
52*7c478bd9Sstevel@tonic-gate2:	bg	1b
53*7c478bd9Sstevel@tonic-gate	subcc	%o5, 4, %o5
54*7c478bd9Sstevel@tonic-gate	! now return new %sp + end-of-temp
55*7c478bd9Sstevel@tonic-gate	retl
56*7c478bd9Sstevel@tonic-gate	add	%sp, %o2, %o0
57*7c478bd9Sstevel@tonic-gate
58*7c478bd9Sstevel@tonic-gate	SET_SIZE(__builtin_alloca)
59