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Convert the i386 alloca(3) to the x86-64 ISA.

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Alignment hack from:	NetBSD
This commit is contained in:
David E. O'Brien 2003-05-01 16:04:38 +00:00
parent 6c0510dc2f
commit d37f19f084
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=114430
1 changed files with 53 additions and 0 deletions
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lib/libc/amd64/gen/alloca.S Normal file
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/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
.asciz "@(#)alloca.s 5.2 (Berkeley) 5/14/90"
#endif /* LIBC_SCCS and not lint */
#include <machine/asm.h>
__FBSDID("$FreeBSD$");
/* like alloc, but automatic automatic free in return */
ENTRY(alloca)
popq %rdx /* pop return addr */
movl %rsp,%rcx
addq $15,%rdi /* round amount to allocate up to 16 bytes */
andq $~15,%rdi
subq %rdi,%rsp
movq %rsp,%rax /* base of newly allocated space */
jmp *%rdx /* "return" */