With point-frag, I am trying to support as many compilers and as many platform (well, Windows, Linux and soon Mac...) as I can. I hope to be able to do a benchmark from it at some point. I anyway quickly compared GCC, ICC and Clang on Linux with my small ray tracing test.
Here the numbers for my nehalem i7 (4 cores / 8 threads, triple channel memory, basically the high end chip 3 years ago). Code is compiled for SSE2 and does not use anything more recent.
ray packet: 90 million rays/s
single rays: 9,9 million rays.s
ray packet: 95.6 million rays/s
single rays: 10.6 million rays.s
CLANG (3.1 compiled from svn)
ray packet: 94.2 million rays/s
single rays: 9.9 million rays.s
With no surprise, the Intel compiler is slightly faster on a Intel processor than the other compilers. More surprisingly, the speed difference is quite small. Two years ago, GCC / ICC difference was about 15% on the same machine. Latest clang also outputs some fast code.
Good job open source compiler guys!