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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/102844] [9/10/11/12/13 Regression] DOM jump
 threading not copying block that became non-empty
Date: Fri, 20 May 2022 08:24:29 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102844

--- Comment #25 from Richard Biener <rguenth at gcc dot gnu.org> ---
I'm not sure about the state of this bug - the issue reproduces on the GCC =
10
branch with checking enabled and -O[2s] -fdisable-tree-fre4
-fno-strict-overflow

It might be that using the backward threader from DOM (are we now doing tha=
t?)
makes this truly fixed but I'm not sure the backward threader is resilent
to the issue analyzed in comments #13 to #15.  Eventually the NOCOPY
special-casing could be removed as premature optimization (CFG cleanup will
remove any copied forwarders), but then IIRC we have a hard limit on the
number of blocks the threader handles.=