From 4a99c8aa2c7225a595d328e58c6fea178cb92bb7 Mon Sep 17 00:00:00 2001
From: netblue30 <netblue30@yahoo.com>
Date: Fri, 30 Mar 2018 08:19:33 -0400
Subject: spectre support for clang compiler

---
 configure.ac | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9a7a9d65e..1f573d50f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,15 +9,21 @@ AC_PROG_INSTALL
 AC_PROG_RANLIB
 
 HAVE_SPECTRE="no"
-AC_MSG_CHECKING(for Spectre mitigation support in gcc compiler)
+AC_MSG_CHECKING(for Spectre mitigation support in gcc or clang compiler)
 AS_IF([test "$CC" = "gcc"], [
 	HAVE_SPECTRE="yes"
 	$CC -mindirect-branch=thunk -c dummy.c || HAVE_SPECTRE="no"
 	rm -f dummy.o
+	EXTRA_CFLAGS+=" -mindirect-branch=thunk "
+])
+AS_IF([test "$CC" = "clang"], [
+	HAVE_SPECTRE="yes"
+	$CC -mretpoline -c dummy.c || HAVE_SPECTRE="no"
+	rm -f dummy.o
+	EXTRA_CFLAGS+=" -mretpoline "
 ])
 AS_IF([test "$HAVE_SPECTRE" = "yes"], [
 	AC_MSG_RESULT(yes)
-	EXTRA_CFLAGS+=" -mindirect-branch=thunk "
 ])
 AS_IF([test "$HAVE_SPECTRE" = "no"], [
 	AC_MSG_RESULT(... not available)
-- 
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