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] Enabling Software Prefetching by Default at -O3


Hi,

> This patch serves as a proposal to turn on software prefetching by default at -O3.

On S/390 I ran into a problem with the runtime of the prefetching pass when using
aggressive loop unrolling.  There is an algorithm with quadratic runtime regarding the
memory references which causes a very long compile time.  Christian already opened a
bugzilla for that (PR 44576). It probably would make sense to have a closer look at this
before enabling the pass by default. Perhaps we could simply limit the miss rate
computation to a certain amount of memory references?

Besides of that enabling the prefetching pass by default is ok with me. I think it would
help getting more people into improving it.

Bye,

-Andreas-


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