From: Richard Biener <rguenther@suse.de>
To: "Gopalasubramanian, Ganesh" <Ganesh.Gopalasubramanian@amd.com>
Cc: Uros Bizjak <ubizjak@gmail.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: RE: [PATCH] Fix bdverN vector cost of cond_[not_]taken_branch_cost
Date: Wed, 08 Apr 2015 07:38:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.11.1504080935320.5207@zhemvz.fhfr.qr> (raw)
In-Reply-To: <EB4625145972F94C9680D8CADD65161578FD1FE8@SATLEXDAG02.amd.com>
On Wed, 8 Apr 2015, Gopalasubramanian, Ganesh wrote:
> > I have added a person from AMD to comment on the decision.
> > Otherwise, the patch looks OK, but please wait a couple of days for possible comments.
>
> Thank you Uros!
> I am checking the changes with few tests and benchmarking them.
> Please wait for a couple of days.
Note that before the fixes for PR64909 the epilogue/prologue loops
had very large costs associated due to a bug in the cost model
implementation. After the fix their cost is reasonable but the
cost of the extra jumps is way under-accounted for due to the
numbers for cond_taken_branch_cost and cond_not_taken_branch_cost.
The proposes match mitigates that somewhat.
How did you arrive at the original cost model?
Thanks,
Richard.
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Jennifer Guild,
Dilip Upmanyu, Graham Norton HRB 21284 (AG Nuernberg)
next prev parent reply other threads:[~2015-04-08 7:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-07 8:19 Richard Biener
2015-04-07 11:20 ` Uros Bizjak
2015-04-08 6:39 ` Gopalasubramanian, Ganesh
2015-04-08 7:38 ` Richard Biener [this message]
2015-04-13 5:49 ` Gopalasubramanian, Ganesh
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