LLVM uses atomic operations, which are not supported on i386 and GCC

emits calls for them, rather than expanding them inline.  Older FreeBSD
versions compile for i386 by default and as such we end up with
unresolved symbols when we build LLVM's TableGen utility as a build
tool on them.  Add the functions that GCC emits here, but don't bother
to make them atomic. Such is not needed.

Submitted by:	marcel
MFC after:	1 week

2 files changed, 60 insertions, 0 deletions

diff --git a/tools/build/Makefile b/tools/build/Makefile
index 8e26c29..4eb7548 100644
--- a/tools/build/Makefile
+++ b/tools/build/Makefile
@@ -7,6 +7,10 @@ SRCS=
 INCSGROUPS=	INCS
 INCS=		
 
+.if ${MACHINE_ARCH} == i386
+SRCS+=		atomic.c
+.endif
+
 BOOTSTRAPPING?=	0
 
 .if empty(SRCS)
diff --git a/tools/build/atomic.c b/tools/build/atomic.c
new file mode 100644
index 0000000..72eef9f
--- /dev/null
+++ b/tools/build/atomic.c
@@ -0,0 +1,56 @@
+/*-
+ * Copyright (c) 2011 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 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <stdint.h>
+
+uint32_t __sync_add_and_fetch_4(uint32_t *, uint32_t);
+uint32_t __sync_sub_and_fetch_4(uint32_t *, uint32_t);
+uint32_t __sync_val_compare_and_swap_4(uint32_t *, uint32_t, uint32_t);
+
+uint32_t
+__sync_add_and_fetch_4(uint32_t *ptr, uint32_t val)
+{
+	*ptr += val;
+	return *ptr;
+}
+
+uint32_t
+__sync_sub_and_fetch_4(uint32_t *ptr, uint32_t val)
+{
+	*ptr -= val;
+	return *ptr;
+}
+
+uint32_t
+__sync_val_compare_and_swap_4(uint32_t *ptr, uint32_t oldval, uint32_t newval)
+{
+	uint32_t res = *ptr;
+	if (res == oldval)
+		*ptr = newval;
+	return res;
+}