[Bug rtl-optimization/50677] volatile forces load into register

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50677

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #4)
> Why doesn't combine include (clobber (reg:CC 17 flags))?

It has nothing to do with the clobber.
Inside combine_instructions there is a call to init_recog_no_volatile which
forces volatile memory not be recognized.  The main reason is because combine
does not check for volatile memory issues before doing the combine so it was
easier to just disable recognizability of volatile memory.