David Edelsohn wrote:
On Thu, Sep 4, 2008 at 7:39 PM, Vladimir Makarov <[EMAIL PROTECTED]> wrote:
Meanwhile I am going to submit your second patch with an added
comment. The patch permits gcc to generate the same quality code as
before your first patch.
Why?
As Richard said before:
"... it changes
the heuristics _without any explanation of why this is necessary_.
IMO, that's unacceptable for our shiny, new (and generally very nice)
register allocator. And I think it's unacceptable even if it happens
to fix a performance regression."
The patch does not seem to have any justification other than it fixes the
symptom.
It fixes the performance degradation. I wrote a long comment for the
macro about necessity of the problem investigation and marked it by
???. The problem is known. It is actually three monts old (that is
when Richard submitted the patch first time). I've tried to find a
reason for the degradation which is not easy when you are trying to do
this on SPEC programs but failed. Richard found one problem on a small
test he thought that it could be a reason. Most part of the problem is
solved now, so I doubt that was a real reason.
Now I am really busy with fixing IRA bugs. So if it is ok to gcc
community to wait for month or two (but may be it will take less who
knows) to find a real reason or explanation of the performance
degradation, it is ok for me too.
