This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: GVN-PRE sucks -- well, for SPECCFP2000 mgrid anyway
On Aug 15, 2004, at 5:05 PM, Mark Mitchell wrote:
Daniel Berlin wrote:
Yeah.
I'll see if i can come up with some simple heuristics that help here,
without hurting anything else too much.
I wonder if it's better to restrain PRE, or let it go ahead, and then
have the register allocator move computations back into the loop.
I've copied Kenny here to see if he happens to know of any magic
bullets for this kind of thing.
(Kenny, the issue is that PRE is pulling so much stuff out of loops
that we get register pressure, and hence bad code.)
Just so I got my say and not get Danny into too much trouble but I will
note that
NAG F95 with gcc 3.3 as the compiler gets around the same score as
gfortran does.
This is on a dual 2.5GHz G5.
-- Pinski