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 (c) 1998, by Sun Microsystems, Inc.
* All rights reserved.
*/
#ident "%Z%%M% %I% %E% SMI"
.file "%M%"
#include <sys/asm_linkage.h>
#include <sys/stack.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 necessary as we could theoretically
! be in the middle of a complicated expression.
!
ENTRY(__builtin_alloca)
add %sp, STACK_BIAS, %g1 ! save current sp + STACK_BIAS
sub %sp, %o0, %sp ! bump to new value
add %sp, STACK_BIAS, %g5
! copy loop: should do nothing gracefully
b 2f
subcc %o2, %o1, %o5 ! number of bytes to move
1:
ldx [%g1 + %o1], %o4 ! load from old temp area
stx %o4, [%g5 + %o1] ! store to new temp area
add %o1, 8, %o1
2: bg,pt %xcc, 1b
subcc %o5, 8, %o5
! now return new %sp + end-of-temp
add %sp, %o2, %o0
retl
add %o0, STACK_BIAS, %o0
SET_SIZE(__builtin_alloca)