+# Turn on vectorization and loop unrolling for matmul.
+$(patsubst %.c,%.lo,$(notdir $(i_matmul_c))): AM_CFLAGS += -ftree-vectorize -funroll-loops
+# Logical matmul doesn't vectorize.
+$(patsubst %.c,%.lo,$(notdir $(i_matmull_c))): AM_CFLAGS += -funroll-loops
+