spectre support for clang compiler

1 files 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)