This was just some quick benchmarking on the A10-7850K system with Ubuntu 14.04 LTS and running the Linux 3.13 kernel while using GCC 4.9.0 20140126 as the primary compiler.
All tests happened when compiling all test profiles with -march=bdver3 as set by the CFLAGS/CXXFLAGS and then -march=bdver2, -march=bdver1, -march=barcelona, and -march=k8. For those wanting more information on what these options mean, checkout the GCC online documentation.
The results from this latest AMD A10-7850K Linux compiler testing are on OpenBenchmarking.org via 1401282-PL-GCC49COMP74. All in all, there isn't much change out of "-march=bdver3" in place of -march=bdver2 for the Steamroller cores on this APU.