[Bug tree-optimization/85509] fails to promote local static to const

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85509

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-04-24
                 CC|                            |hubicka at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
          Component|c++                         |tree-optimization
            Summary|auto (function pointer)     |fails to promote local
                   |undermining inline          |static to const
                   |expansion with GCC but not  |
                   |LLVM                        |
     Ever confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
The issue is you fail to make PerformQuickly and PerformSafely const and GCC
doesn't have local analysis to promote it so and IPA analysis is too late
for that since it is also the last inlining point.

Slight complication is nested functions and OMP outlining which may refer to
these variables.  But even the initial cgraph build should be able to figure
out the const-ness, no?

Workaround: make the vars const.