As I already commented, there is one possible reason:

Currently, the conv_acc_sse.c is being compiled with
both -msse3 -msse4.1 CFLAGS. Some compilers (or different
versions) may use the msse4.1 instruction set to optimize
the whole byte code, even in the places where they are not
actually used. So, one possible solution is to separate the
conv_acc_sse.c to conv_acc_sse_3.c and conv_acc_sse_41.c,
and then compile them with -msse3 -msse4.1 flags respectively.