[Bug tree-optimization/34416] Tree optimization pipeline needs re-tuning

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #3 from rguenther at suse dot de  2007-12-10 12:32 -------
Subject: Re:  Tree optimization pipeline needs
 re-tuning

On Mon, 10 Dec 2007, steven at gcc dot gnu dot org wrote:

> Insert usual rant about running more and more and more and more and more and
> more and more and more and more and more and more passes, with total disregard
> for compilation time of the common cases where optimization doesn't do anything
> but increasing compile time.
> 
> Before adding more passes, add some mechanism/heuristics to only run passes
> when benefit is expected.  Not the whole world is tramp3d.  Please take glibc
> and the linux kernel (or other codes with almost no abstraction) as compile
> time indicators for a change, too.

:)

Apart from the early loop unrolling which has benefits for Fortran code,
I was only suggesting to re-order things, not to add additional passes.

But yes, adding passes is usually far easier to make regression-free
from a runtime performance point.  And removing anything from GCC is
at least 10 times harder than adding something - which you know, I bet ;)

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34416