http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60086
--- Comment #9 from Alexander Monakov <amonakov at gcc dot gnu.org> --- By "good code" I was referring to the fact that your 4.7 asm does not contain stack (%rbp) references in the vectorized loop. Historically, first scheduling (-fschedule-insns) was problematic for 32-bit x86 due to increase of register pressure to the point that register allocator couldn't handle. The situation got much better with the introduction of -fsched-pressure, and was tuned a bit further recently. I don't know the latest status; I think compile time cost is the reason it's not enabled at -O2. For regrename, the manpage notes there are debug info issues on some targets; I don't know if there's anything else beside that.
