This is the mail archive of the
mailing list for the GCC project.
Re: GCSE store motion
- From: Roger Sayle <roger at eyesopen dot com>
- To: Daniel Berlin <dberlin at dberlin dot org>
- Cc: <gcc at gcc dot gnu dot org>, Mark Mitchell <mark at codesourcery dot com>, "David S. Miller" <davem at redhat dot com>, Andreas Jaeger <aj at suse dot de>, Richard Henderson <rth at redhat dot com>
- Date: Wed, 15 May 2002 10:37:42 -0600 (MDT)
- Subject: Re: GCSE store motion
> I am completely for disabling optimizations on the mainline that do
> nothing but waste time in their current state (though even a 1%
> improvement might be arguably worth it).
You'll also be aware of the "Store merging" section of the "Optimizer
inadequecies" page, http://gcc.gnu.org/projects/optimize.html#storemerge
Although store motion isn't particularly functional at the moment, it
provides a framework for further GCC improvements in the future.
I'd agree that perhaps is should be in -fexpensive-optimizations, but
I'm not convinced that its broken. As you point out in your commentary
of its deficiencies, it pessimizes const/pure functions etc..., but
these don't affect the correctness of the code, just decrease the number
of places this optimization is applicable.