usr/src/lib/libc/amd64/gen/alloca.s

   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)