This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] Take branch misprediction effects into account when RTL loop unrolling (issue6099055)


> Tree level unrollers (cunrolli and cunroll) do complete unroll. At O2,
> both of them are turned on, but gcc does not allow any code growth --
> which makes them pretty useless at O2 (very few loops qualify). The
> default max complete peel iteration is also too low compared with both
> icc and llvm.  This needs to be tuned.

I found that at -O3 (where tree unroll is on by default) there is quite a 
bit of useless unrolling. I got somewhat irritated that my printf debug loops 
were commonly unrolled.

-Andi


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]