GCC 4.3.2 and -march=native
While configuring a new Gentoo Linux workstation I came across -march=native CFLAGS. Glancing over at GCC documentation, as of version 4.3.2 GCC is capable of automatically detecting what CPU you are using and setting appropriate optimization options.
32bit Users
CHOST="i686-pc-linux-gnu" CFLAGS="-march=native -O2 -pipe" CXXFLAGS="${CFLAGS}"
64bit Users
CHOST="x86_64-pc-linux-gnu" CFLAGS="-march=native -O2 -pipe" CXXFLAGS="${CFLAGS}"