diff options
Diffstat (limited to 'lib/libc/amd64/gen')
| -rw-r--r-- | lib/libc/amd64/gen/alloca.S | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/lib/libc/amd64/gen/alloca.S b/lib/libc/amd64/gen/alloca.S new file mode 100644 index 0000000..e3c7794 --- /dev/null +++ b/lib/libc/amd64/gen/alloca.S @@ -0,0 +1,53 @@ +/*- + * 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" */ |
