[Bug tree-optimization/40073] Vector short/char shifts generate sub-optimal code

[alalaw01 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40073

--- Comment #8 from alalaw01 at gcc dot gnu.org ---
Is there a case where the result is different with vs without all the
extending/truncating?

It seems we should need the extending/truncating on vectors exactly iff we need
it on scalars?