[Bug c/81128] New: Function multi-versioning does not work with -Ofast

[billy.o.mahony at intel dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81128

            Bug ID: 81128
           Summary: Function multi-versioning does not work with -Ofast
           Product: gcc
           Version: 6.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: billy.o.mahony at intel dot com
  Target Milestone: ---

Created attachment 41584
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41584&action=edit
c code

Hi All,

I've been investigating function multi-versioning feature and it works as
expected except when I compile with -Ofast.

When adding -Ofast to the compile what I see is that each time the
multi-versioned function is called is that the *resolver* is called but that
neither of the implementations are called.

Code, build commands and example outputs & .asm attached. 

Regards,
Billy