On 25 June 2014 10:26, Bingfeng Mei <b...@broadcom.com> wrote: > Why is GCC code size so much bigger than LLVM? Does -Ofast have more unrolling > on GCC? It doesn't seem increasing code size help performance (164.gzip & > 197.parser) > Is there comparisons for O2? I guess that is more useful for typical > mobile/embedded programmers.
Hi Bingfeng, My analysis wasn't as thorough as Vladimir's, but I found that GCC wasn't eliminating some large blocks of dead code or inlining as much as LLVM was. I haven't dug deeper, though. Some of the differences were quite big, I'd be surprised if it all can be explained by unrolling loops and vectorization... cheers, --renato
