[gillianseed]

I have and yes ICC generally won on our tests but:

A) it's proprietary, I have no interest in relying on a proprietary toolchain (and from what I gather neither does the company I work for)

B) it supports a very limited range of cpu architectures, not only is it directly tailored for Intel cpu's it even has a history of selecting poor code paths for AMD cpu's.

As for manual loop unrolling, for alot of code PGO does a great job here by unrolling based on the statistics gathered during the first pass. In fact GCC's pgo seems to do a better job than ICC's pgo implementation, ICC's lto beats GCC's on the other hand, and of course ICC does a better job at vectorization and has better optimized math functions.