[patch] for PR35164

[Zdenek Dvorak]

Hi,

> >  a missing test for abnormal SSA names in forwprop causes us to extend
> >  their life ranges, and consequently ICE in out-of-ssa.  Bootstrapped
> >  & regtested on x86_64.
> 
> Actually I have a similar patch that splits the check out to a helper function
> (it might prove useful elsewhere) and adds the other testcase as well.
> 
> Do you mind if I chose to apply that version?  Attached for reference.

sure, ok with me,

Zdenek