Add -fno-slp-vectorize to clang++.

diff --git a/configure.ac b/configure.ac
index cc6769ab5f3a6416477a2ca013c248f3ecc094b4..d8bc1013e6dffbd39aab41615ba31ca5c18883bf 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -249,6 +249,9 @@ if test x"$SIMD" != x""; then
     SIMD='$(SIMD_'"$SIMD)"
     # We only use c++ for its target attribute dispatching, disable unneeded bulky features
     CXXFLAGS="$CXXFLAGS -fno-exceptions -fno-rtti"
+    case "$CXX" in
+    *clang*) CXXFLAGS="$CXXFLAGS -fno-slp-vectorize" ;; # avoid a performance hit
+    esac
 else
     AC_MSG_RESULT(no)
 fi