[Bug c++/70847] [6/7 Regression] exponential time in cp_fold for chained virtual function calls

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70847

--- Comment #14 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #13)
> Created attachment 38638 [details]
> gcc7-pr70847.patch
> 
> So, shall I test this version?
> As added bonus, if cp_fold returns for different stmts the same return value
> for whatever reason, we wouldn't walk the subtrees on it more than once.

Looks good to me!