[Bug middle-end/68785] [6 Regression] valgrind reports issues with folding on x86_64

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68785

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 36971
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36971&action=edit
gcc6-pr68785.patch

Sure, it is undefined behavior, but I believe we should spend the minimum
amount of code on it.  And that IMHO is this, using the APIs the way they were
meant to be used when added.  It won't be folded, but why should we spend time
folding something that is invalid.