usr/src/lib/libbc/libc/gen/common/sparc/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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1990 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*
  28  *      .seg    "data"
  29  *      .asciz ident    "%Z%%M% %I%     %E% SMI"
  30  */
  31 !       .seg    "text"
  32
  33         .file   "alloca.s"
  34
  35 #include <sun4/asm_linkage.h>
  36
  37         !
  38         ! o0: # bytes of space to allocate, already rounded to 0 mod 8
  39         ! o1: %sp-relative offset of tmp area
  40         ! o2: %sp-relative offset of end of tmp area
  41         !
  42         ! we want to bump %sp by the requested size
  43         ! then copy the tmp area to its new home
  44         ! this is necessasy as we could theoretically
  45         ! be in the middle of a compilicated expression.
  46         !
  47         ENTRY(__builtin_alloca)
  48         mov     %sp, %o3                ! save current sp
  49         sub     %sp, %o0, %sp           ! bump to new value
  50         ! copy loop: should do nothing gracefully
  51         b       2f
  52         subcc   %o2, %o1, %o5           ! number of bytes to move
  53 1:
  54         ld      [%o3 + %o1], %o4        ! load from old temp area
  55         st      %o4, [%sp + %o1]        ! store to new temp area
  56         add     %o1, 4, %o1
  57 2:      bg      1b
  58         subcc   %o5, 4, %o5
  59         ! now return new %sp + end-of-temp
  60         retl
  61         add     %sp, %o2, %o0
  62         SET_SIZE(__builtin_alloca)