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From: "law at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/103721] [12 regression] wrong code generated for loop with conditional since r12-4790-g4b3a325f07acebf4
Date: Wed, 19 Jan 2022 22:51:06 +0000	[thread overview]
Message-ID: <bug-103721-4-cG18uR9VEx@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103721-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103721

--- Comment #9 from Jeffrey A. Law <law at gcc dot gnu.org> ---
I think Andrew has raised a really interesting issue.  If the relation code is
designed around seeing things in dominator order, then don't we have to stop
using it once we traverse any edge where the edge source does not dominate the
edge destination (assume this is a partial graph rather than a multi-entry
function ;-)



   1  2   3
   |   \ /
   |    4
   |   / \
   +->5   6
     / \
    7   8


Note how BB4 does not dominate BB5.  If we try to thread something like
2->4->5->?, then can't we run into problems with the equivalence handling as
well, even though we're not dealing with a loop?

  parent reply	other threads:[~2022-01-19 22:51 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-14 22:19 [Bug tree-optimization/103721] New: [12 regression] wrong code generated for loop with conditional (jump threading?) sss@li-snyder.org
2021-12-14 22:21 ` [Bug tree-optimization/103721] " pinskia at gcc dot gnu.org
2021-12-14 23:03 ` pinskia at gcc dot gnu.org
2021-12-15 11:27 ` [Bug tree-optimization/103721] [12 regression] wrong code generated for loop with conditional since r12-4790-g4b3a325f07acebf4 marxin at gcc dot gnu.org
2022-01-04 11:16 ` rguenth at gcc dot gnu.org
2022-01-06 20:13 ` amacleod at redhat dot com
2022-01-18  4:02 ` law at gcc dot gnu.org
2022-01-18 18:49 ` amacleod at redhat dot com
2022-01-19 12:44 ` aldyh at gcc dot gnu.org
2022-01-19 16:40 ` aldyh at gcc dot gnu.org
2022-01-19 16:58 ` amacleod at redhat dot com
2022-01-19 22:51 ` law at gcc dot gnu.org [this message]
2022-01-20  0:10 ` amacleod at redhat dot com
2022-01-20 11:13 ` aldyh at gcc dot gnu.org
2022-01-20 11:14 ` aldyh at gcc dot gnu.org
2022-01-20 13:28 ` aldyh at gcc dot gnu.org
2022-01-20 14:12 ` amacleod at redhat dot com
2022-01-21 10:19 ` cvs-commit at gcc dot gnu.org
2022-01-21 10:30 ` aldyh at gcc dot gnu.org

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