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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109192] [13 Regression] timeout with -O3 since r13-5579
Date: Tue, 21 Mar 2023 10:33:26 +0000	[thread overview]
Message-ID: <bug-109192-4-6zpu2n01d1@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109192-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109192

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Macleod from comment #7)
> Created attachment 54716 [details]
> proposed patch
> 
> This is due to the latter part of the specified patch.  We normally
> terminate outgoing range calculations once the LHS has reverted to VARYING
> as we won't learn anything new.
> 
> The original patch modified this such that if there was a relation present,
> we continued calculating as the relation may provide new information, as per
> the original PR.
> 
> The problem exposed in this PR is that the presence of a relation doesn't
> mean that relation can actually affect the range.  This PR shows many
> relations, none of which are relevant, and with the quadratic nature of the
> path query, it makes things quite bad.
> 
> The attached patch is in testing.  It adds a check to determine if the
> relation can affect the outgoing range or not by checking if the operands
> are used in the calculation or not.  If they are not in the definition
> chain, they can have no impact, and we stop the attempt.

Sounds reasonable without knowing all the details in the implementation.
How does it affect compile-times on the testcase?

  parent reply	other threads:[~2023-03-21 10:33 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-19 10:20 [Bug c/109192] New: timeout with -g -O3 -fno-var-tracking ? dcb314 at hotmail dot com
2023-03-19 16:56 ` [Bug middle-end/109192] timeout with " dcb314 at hotmail dot com
2023-03-19 17:18 ` dcb314 at hotmail dot com
2023-03-19 17:18 ` dcb314 at hotmail dot com
2023-03-19 19:11 ` [Bug tree-optimization/109192] [13 Regression] timeout with -O3 -fno-var-tracking since r13-5579 pinskia at gcc dot gnu.org
2023-03-20 10:25 ` [Bug tree-optimization/109192] [13 Regression] timeout with -O3 " rguenth at gcc dot gnu.org
2023-03-20 10:35 ` rguenth at gcc dot gnu.org
2023-03-20 20:20 ` amacleod at redhat dot com
2023-03-21 10:33 ` rguenth at gcc dot gnu.org [this message]
2023-03-21 14:15 ` cvs-commit at gcc dot gnu.org
2023-03-21 14:15 ` amacleod at redhat dot com
2023-03-21 14:20 ` rguenth at gcc dot gnu.org
2023-03-28  7:52 ` chenglulu at loongson dot cn
2023-03-28  8:07 ` chenglulu at loongson dot cn
2023-03-28 13:22 ` amacleod at redhat dot com
2023-03-30  1:04 ` chenglulu at loongson dot cn

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