Add support for ia64.

Note that the tp register (r13) is reserved as the TLS pointer in
the same way that that gp register (r1) is reserved as the global
pointer. This implementation uses the tp register to point to the
thread structure used by the threads implementation. This is not
in violation with the runtime specification provided the TLS is
a fixed distance from the thread structure. This is only an issue
when code used the __thread keyword to create TLS. This is not
supported at the moment.

lib/libthr/arch/ia64/Makefile.inc

@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+.PATH:	${.CURDIR}/sys ${.CURDIR}/arch/${MACHINE_ARCH}/${MACHINE_ARCH}
+
+SRCS+=	_curthread.c

lib/libthr/arch/ia64/ia64/_curthread.c

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2003 Marcel Moolenaar
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/ucontext.h>
+
+#include <pthread.h>
+#include "thr_private.h"
+
+register struct pthread *_tp __asm("%r13");
+
+struct pthread *
+_get_curthread(void)
+{
+
+	return (_tp);
+}
+
+void
+_retire_thread(void *v)
+{
+}
+
+void *
+_set_curthread(ucontext_t *uc, struct pthread *thread)
+{
+
+	if (uc != NULL)
+		uc->uc_mcontext.mc_gr[13] = (uint64_t)thread;
+	else
+		_tp = thread;
+	return (NULL);
+}