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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111293] [14 Regression] Missed Dead Code
 Elimination since r14-3414-g0cfc9c953d0
Date: Fri, 24 Nov 2023 15:56:02 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111293

--- Comment #2 from Andrew Macleod <amacleod at redhat dot com> ---
It seems like we set 'e' to 3 immediately at the start:
  <bb 2> [local count: 1073741824]:
  e =3D 3;
  goto <bb 10>; [100.00%]

and it is never changed again. However, when we load from 'e' later in the =
IL
  <bb 3> [local count: 9485263241]:
  e.1_6 =3D e;

we simply get varying. Is some pass suppose to propagate this?  This remind=
s me
of a few other regression PRs where we no longer propagate known values from
loads from memory into ssa-names.

If we knew that e.1_6 was '3', then the call to foo would be folded away as
never executable.=