[Bug c++/83778] [8 regression] g++.dg/ext/altivec-cell-2.C fails starting with r256448

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83778

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 43118
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43118&action=edit
gcc8-pr83778.patch

This restores the previous behavior for me.  Note, the question is whether the
4 is really invalid, in that case perhaps we shouldn't fold it to something
early and let it error during expansion.