--- /usr/portage/media-libs/mesa/mesa-18.3.2.ebuild	2019-01-28 07:09:29.000000000 +0300
+++ /usr/local/portage/media-libs/mesa/mesa-18.3.2.ebuild	2019-01-30 19:28:07.001804146 +0300
@@ -317,6 +317,12 @@ pkg_setup() {
 	python-any-r1_pkg_setup
 }
 
+src_prepare(){
+	default
+	# must be regenerated
+	rm "src/gallium/drivers/swr/rasterizer/jitter/gen_builder.hpp" || die
+}
+
 multilib_src_configure() {
 	local emesonargs=()
 
@@ -441,6 +447,27 @@ multilib_src_configure() {
 	fi
 
 	if use gallium; then
+		if [[ ${ABI} == amd64 ]] && use llvm; then
+			local i f swr=
+			for i in knl skx avx2 avx; do
+				case ${i} in
+				knl)f=AVX512F;;
+				skx)f=AVX512BW;;
+				*)f=${i^^};;
+				esac
+				echo "#ifndef __${f}__
+#error
+#endif"|$(tc-getCPP) - -o /dev/null ${CXXFLAGS} 2>/dev/null || continue
+				swr+=,${i}
+				break
+			done
+			swr=${swr#,}
+			if [[ -n "${swr}" ]]; then
+				gallium_enable -- swr
+				emesonargs+=( -Dswr-arches=${swr} )
+			fi
+
+		fi
 		gallium_enable -- swrast
 		emesonargs+=( -Dosmesa=$(usex osmesa gallium none) )
 	else