From: Vladimir Makarov <vmakarov@redhat.com>
To: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 3/8] Remove cached_first_cycle_multipass_dfa_lookahead and cached_issue_rate
Date: Tue, 21 Oct 2014 15:53:00 -0000 [thread overview]
Message-ID: <5446815C.6050609@redhat.com> (raw)
In-Reply-To: <EF6BB45F-FB61-4134-A9D0-FBF0AD2E70EE@linaro.org>
On 10/20/2014 11:16 PM, Maxim Kuvyrkov wrote:
> Hi,
>
> This patch cleans up (removes) cached_first_cycle_multipass_dfa_lookahead and cached_issue_rate.
>
> These seem to be an artifact from the scheduler refactoring 10+ years ago. They assume that dfa_lookahead and issue_rate can change mid-way through scheduling, which is never the case. All backends currently treat dfa_lookahead and issue_rate as constants for the duration of scheduling passes.
>
> Bootstrapped on x86_64-linux-gnu. Regression testing is in progress. OK to commit if no regressions?
>
Yes. the patch for issue rate itself is ok but you should have modified
doc/tm.texi too for dfa lookahead hook saying that it should be a
constant (issue rate already has such clause).
On the other hand I'd not assume that dfa look ahead is a constant. In
future we could make it non-constant to differentiate non-hot and hot
functions to speed up the scheduler as dfa look ahead scheduling is
pretty expensive.
So issue rate change is ok but I'd not rush to change dfa look ahead
related code.
next prev parent reply other threads:[~2014-10-21 15:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-21 3:21 Maxim Kuvyrkov
2014-10-21 15:53 ` Vladimir Makarov [this message]
2014-10-23 3:34 ` Maxim Kuvyrkov
2014-10-24 3:21 ` Vladimir Makarov
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