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

[glisse at gcc dot gnu.org]

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

Marc Glisse <glisse at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |law at gcc dot gnu.org

--- Comment #9 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to alalaw01 from comment #8)
> 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?

The extending/truncating is what the standard requires. Then we can start
optimizing (since indeed in many cases it isn't necessary), and Jeff is working
on exactly that (shortening). This seems like a rather straightforward case,
but who knows...