alloca.s revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 1990 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* .seg "data"
* .asciz ident "%Z%%M% %I% %E% SMI"
*/
! .seg "text"
.file "alloca.s"
#include <sun4/asm_linkage.h>
!
! o0: # bytes of space to allocate, already rounded to 0 mod 8
! o1: %sp-relative offset of tmp area
! o2: %sp-relative offset of end of tmp area
!
! we want to bump %sp by the requested size
! then copy the tmp area to its new home
! this is necessasy as we could theoretically
! be in the middle of a compilicated expression.
!
ENTRY(__builtin_alloca)
mov %sp, %o3 ! save current sp
sub %sp, %o0, %sp ! bump to new value
! copy loop: should do nothing gracefully
b 2f
subcc %o2, %o1, %o5 ! number of bytes to move
1:
ld [%o3 + %o1], %o4 ! load from old temp area
st %o4, [%sp + %o1] ! store to new temp area
add %o1, 4, %o1
2: bg 1b
subcc %o5, 4, %o5
! now return new %sp + end-of-temp
retl
add %sp, %o2, %o0
SET_SIZE(__builtin_alloca)