Peter Bergner wrote:
On Thu, 2008-09-04 at 20:28 -0400, 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."
I have to agree with Richard and David here. I find it troubling that
allocation order affects performance by anything other than a small
amount due to heuristic noise. It might be in the end there is a
valid reason on why Richard's patch has a positive benefit, but until
we know why, I'd rather wait.
Peter
Agreed. Let's at least have a reasonable explanation of why this is
affecting performance so much. In theory, this kind of change ought to
be in the noise.
Jeff
