https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68548

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-11-26
                 CC|                            |manu at gcc dot gnu.org
            Version|unknown                     |6.0
             Blocks|                            |24639
            Summary|gcc wrongly warns about     |bogus "may be used
                   |uninitialized data          |uninitialized" (predicate
                   |                            |analysis)
     Ever confirmed|0                           |1

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Matt Turner from comment #0)
> Created attachment 36842 [details]
> u.c
> 
> gcc -Wmaybe-uninitialized wrongly warns about data0 being uninitialized in
> the attached test case.
> 
> This may be a duplicate of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42145

No, it is not. This is just that the uninit predicate analysis is not powerful
enough. It sees that the DEF is guarded by writemask_3(D) & 1, but it sees that
the use is guarded by remaining_8 == 0, and it doesn't seem to analyse further
than that.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639
[Bug 24639] [meta-bug] bug to track all Wuninitialized issues

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