From: Richard Biener <richard.guenther@gmail.com>
To: Feng Xue OS <fxue@os.amperecomputing.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
Jeff Law <law@redhat.com>
Subject: Re: [PATCH] Remove empty loop with assumed finiteness (PR tree-optimization/89713)
Date: Mon, 20 May 2019 11:54:00 -0000 [thread overview]
Message-ID: <CAFiYyc1Xv+VpAv1Ryrh9j3GGwoLgAeNv11Th0otBdteEt5a3_A@mail.gmail.com> (raw)
In-Reply-To: <BYAPR01MB4869B1C71BB681191B4DA689F7060@BYAPR01MB4869.prod.exchangelabs.com>
On Mon, May 20, 2019 at 11:48 AM Feng Xue OS
<fxue@os.amperecomputing.com> wrote:
>
> >> Now finiteness assertion is only used in a very late CD-DCE, which is located after all loop optimizations are done. And we can even place it as late as just before RTL-expansion. This might be safe enough to let hidden infinite loops exposed.
>
>
> > Is that so? The early pipeline contains a CD-DCE pass as well. Note we also
> > have pure/const discovery affected by this.
>
> I specialized a CD-DCE pass, named CD-DCE2, and only in this pass, loop removal based on assumed finteness is performed. Please check the patch.
Oh, but why not generally do this?
> >> Now we still need to define "non-trivial exit condition" and a way to
> actually test for that.
>
> Still not very clear on "non-trival exit condition". I think if a loop contains non-EH exit, it is terminable.
Possibly, but that's not terminology for user-facing documentation ;)
I'd even say if a loop contains an exit
it is terminable (remove the non-EH qualification).
Richard.
> Feng
>
>
next prev parent reply other threads:[~2019-05-20 11:54 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-17 4:17 Feng Xue OS
2019-05-17 16:47 ` Jeff Law
2019-05-17 18:50 ` Richard Biener
2019-05-18 14:00 ` Marc Glisse
2019-05-20 7:50 ` Richard Biener
2019-05-20 8:27 ` Feng Xue OS
2019-05-20 9:19 ` Richard Biener
2019-05-20 9:48 ` Feng Xue OS
2019-05-20 11:54 ` Richard Biener [this message]
2019-05-20 14:00 ` Feng Xue OS
2019-05-20 14:04 ` Richard Biener
2019-05-20 14:51 ` Feng Xue OS
2019-05-21 10:12 ` Richard Biener
2019-05-21 14:24 ` Richard Biener
2019-05-22 13:44 ` Michael Matz
2019-05-24 16:02 ` [PATCH V3] " Feng Xue OS
2019-05-24 9:15 ` [PATCH V2] " Feng Xue OS
2019-05-29 11:16 ` Richard Biener
2019-06-04 6:49 ` [PATCH V4] " Feng Xue OS
2019-06-04 8:24 ` Marc Glisse
2019-06-04 15:16 ` [PATCH V5] " Feng Xue OS
2019-06-04 15:24 ` [PATCH V6] " Feng Xue OS
2019-06-05 11:05 ` Richard Biener
2019-06-06 10:00 ` [PATCH V7] " Feng Xue OS
2019-06-11 2:40 ` [PATCH V8] " Feng Xue OS
2019-06-12 9:43 ` Richard Biener
2019-06-15 12:05 ` [committed][nvptx, libgomp] Update pr85381-{2,4}.c test-cases Tom de Vries
2019-05-20 13:04 ` [PATCH] Remove empty loop with assumed finiteness (PR tree-optimization/89713) Marc Glisse
2019-05-20 13:26 ` Richard Biener
2019-05-20 14:49 ` Michael Matz
2019-05-21 8:06 ` Marc Glisse
2020-04-01 13:36 ` [PATCH][RFC] c/94392 - only enable -ffinite-loops for C++ Richard Biener
2020-04-01 13:47 ` Jakub Jelinek
2020-04-01 13:52 ` Richard Biener
2020-04-01 15:56 ` Jan Hubicka
2020-04-01 16:59 ` Richard Biener
2020-04-01 19:15 ` Jason Merrill
2020-04-02 9:12 ` Richard Biener
2020-04-02 9:17 ` Jakub Jelinek
2020-04-02 9:41 ` Richard Biener
2020-04-03 8:29 ` Revert "[nvptx, libgomp] Update pr85381-{2, 4}.c test-cases" [PR89713, PR94392] (was: [PATCH][RFC] c/94392 - only enable -ffinite-loops for C++) Thomas Schwinge
2020-04-03 9:36 ` Revert "[nvptx, libgomp] Update pr85381-{2,4}.c " Richard Biener
2020-04-03 10:34 ` Jakub Jelinek
2020-10-30 14:09 ` Revert "[nvptx, libgomp] Update pr85381-{2, 4}.c " Thomas Schwinge
2020-10-30 14:16 ` Revert "[nvptx, libgomp] Update pr85381-{2,4}.c " Jakub Jelinek
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