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

Alignment hack from:	NetBSD

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" */