From 10b064ffe902d5af31bb49bd8e4f03c545f8d462 Mon Sep 17 00:00:00 2001
From: Ladislav Michl <ladis@linux-mips.org>
Date: Tue, 13 Nov 2012 11:19:47 +0100
Subject: Support building with older compilers.

Add a check for __builtin_unreachable.
---
 configure.ac | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'configure.ac')

diff --git a/configure.ac b/configure.ac
index cffe19b1..7d549aac 100644
--- a/configure.ac
+++ b/configure.ac
@@ -285,6 +285,17 @@ if test x$have__builtin___clear_cache = xyes; then
 fi
 AC_MSG_RESULT([$have__builtin___clear_cache])
 
+AC_MSG_CHECKING([for __builtin_unreachable])
+AC_LINK_IFELSE(
+  [AC_LANG_PROGRAM([[]], [[__builtin_unreachable()]])],
+  [have__builtin_unreachable=yes],
+  [have__builtin_unreachable=no])
+if test x$have__builtin_unreachable = xyes; then
+  AC_DEFINE([HAVE__BUILTIN_UNREACHABLE], [1],
+            [Defined if __builtin_unreachable() is available])
+fi
+AC_MSG_RESULT([$have__builtin_unreachable])
+
 AC_MSG_CHECKING([for __sync atomics])
 AC_LINK_IFELSE(
   [AC_LANG_PROGRAM([[]], [[
-- 
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