[Bug middle-end/71177] Spurious -Waggressive-loop-optimizations warning

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71177

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-05-18
                 CC|                            |manu at gcc dot gnu.org
            Summary|[6 Regression] Spurious     |Spurious
                   |-Waggressive-loop-optimizat |-Waggressive-loop-optimizat
                   |ions warning                |ions warning
     Ever confirmed|0                           |1
      Known to fail|                            |5.3.0, 6.1.1, 7.0

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
Please don't set regression markers if you don't know what you are doing (but
feel free to suggest that something should have regression markers).

Happens also in 5.3.0, 4.9.3 and 7.0, so not a regression.

If you could reduce the testcase further and point out at a missing
optimization, the chances of getting this fixed would increase. Otherwise,
someone needs to look at the dump files and figure out why the ranges are not
affected by the check and whether they should.

The 'else' block is not unreachable, but loop optimizations look at the
possible ranges within the loop and those may not be taking into account any
range information derived from the caller.