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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/18501] [8/9/10/11 Regression] Missing 'used
 uninitialized' warning (CCP)
Date: Wed, 07 Apr 2021 23:41:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D18501

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |10.2.0, 11.0, 4.7.0, 4.8.4,
                   |                            |4.9.4, 5.5.0, 6.4.0, 7.2.0,
                   |                            |8.3.0, 9.1.0
   Last reconfirmed|2018-11-03 00:00:00         |2021-4-7
           See Also|https://gcc.gnu.org/bugzill |
                   |a/show_bug.cgi?id=3D24639     |

--- Comment #95 from Martin Sebor <msebor at gcc dot gnu.org> ---
Reconfirmed with GCC 11.

I wonder if running CCP first, just before the early uninit pass, but only =
to
propagate constants and without modifying the CFG, and then the "late"
uninitialized pass to look for uninitialized operands in the PHIs while
evaluating the predicates using the CCP lattice values, would be a way to g=
et
back the warnings without introducing false positives.=