[Bug middle-end/123175] [14/15/16 Regression] Wrong folding of VEC_PERM_EXPR

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123175

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 63076
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63076&action=edit
expose the issue with __builtin_shufflevector

This is the patch I noticed the problem with.