From: Bernd Schmidt <bernds@codesourcery.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Thomas Schwinge <thomas@codesourcery.com>,
<gcc-patches@gcc.gnu.org>,
Nathan Sidwell <nathan@codesourcery.com>,
Julian Brown <julian@codesourcery.com>
Subject: Re: [gomp4] Preserve NVPTX "reconvergence" points
Date: Mon, 22 Jun 2015 14:04:00 -0000 [thread overview]
Message-ID: <558814DD.2050502@codesourcery.com> (raw)
In-Reply-To: <20150619134529.GP10247@tucnak.redhat.com>
On 06/19/2015 03:45 PM, Jakub Jelinek wrote:
> I actually believe having some optimization passes in between the ompexp
> and the lowering of the IR into the form PTX wants is highly desirable,
> the form with the worker-single or vector-single mode lowered will contain
> too complex CFG for many optimizations to be really effective, especially
> if it uses abnormal edges. E.g. inlining supposedly would have harder job
> etc. What exact unpredictable effects do you fear?
Mostly the ones I can't predict. But let's take one example, LICM: let's
say you pull some assignment out of a loop, then you find yourself in
one of two possible situations: either it's become not actually
available inside the loop (because the data and control flow is not
described correctly and the compiler doesn't know what's going on), or,
to avoid that, you introduce additional broadcasting operations when
entering the loop, which might be quite expensive.
Bernd
next prev parent reply other threads:[~2015-06-22 14:00 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-28 14:20 Julian Brown
2015-05-28 14:59 ` Jakub Jelinek
2015-05-28 15:14 ` Thomas Schwinge
2015-05-28 15:28 ` Jakub Jelinek
2015-06-19 10:44 ` Bernd Schmidt
2015-06-19 12:32 ` Jakub Jelinek
2015-06-19 13:07 ` Bernd Schmidt
2015-06-19 14:10 ` Jakub Jelinek
2015-06-22 14:04 ` Bernd Schmidt [this message]
2015-06-22 14:25 ` Jakub Jelinek
2015-06-24 13:37 ` Bernd Schmidt
2015-06-24 14:08 ` Jakub Jelinek
2015-06-22 14:00 ` Julian Brown
2015-06-22 14:36 ` Jakub Jelinek
2015-06-22 15:18 ` Julian Brown
2015-06-22 15:33 ` Bernd Schmidt
2015-06-22 16:13 ` Nathan Sidwell
2015-06-22 16:27 ` Jakub Jelinek
2015-06-22 16:35 ` Nathan Sidwell
2015-06-22 17:54 ` Julian Brown
2015-06-22 18:48 ` Jakub Jelinek
2015-05-28 15:02 ` Richard Biener
2015-06-03 11:47 ` Julian Brown
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