rfc: auto-casted vector types

[Zack Weinberg]

Aldy Hernandez <aldy@andrews.edu> writes:

> ping.
>
> could i get some comments on this, or the patches look sensible enough
> to submit for inclusion?

It looks decent to me.  I would suggest that here

>> + @findex TARGET_VECTOR_TYPES_COMPATIBLE
>> + @item TARGET_VECTOR_TYPES_COMPATIBLE(@var{tree1}, @var{tree2})
>> + Define this macro to return nonzero if no cast is needed when copying
>> + a value of type @var{tree1} to a value of type @var{tree2}.

you say that this works only for vector types (I realize this is
implied by the name, but it should be said explicitly anyway); and
rather than putting #ifdefs in c-typeck.c, make this a target hook
whose default is 'always return 0'.

zw