These tests aren't really anything Calxeda-specific, but while out at their office in Austin I did carry out a comparison of GCC 4.6, 4.7, and a 4.8 development snapshot. Benchmarking the GNU Compiler Collection from this system made it a breeze due to the fast Cortex-A9 quad-core performance of their server nodes rather than running the compiler tests from a more lax ARM development board. This compiler comparison isn't looking at any Calxeda-specific optimizations but simply testing the GCC 4.6/4.7/4.8-snapshot binaries offered from the Ubuntu 12.10 "Quantal Quetzal" repository while targeting the ARMv7 architecture. The compiler flags for the tests built each time were maintained the same when swapping out the underlying compiler.
If you are not too interested in ARMv7 but rather x86 in other conditions, see the new AMD Piledriver compiler tuning (Bulldozer 2), performance between GCC optimization levels, GCC Link-Time Optimizations, and benchmarking GCC 4.2 through GCC 4.8 on AMD/Intel hardware for similar tests.