rfc: auto-casted vector types

[Geoff Keating]

Jim Wilson <wilson@redhat.com> writes:

> It might be useful to note in the comments in the rs6000 file that the
> current implementation has a known flaw.  It pretends that V2SI is the opaque
> vector type.  This means that it accidentally allows conversions to/from the
> V2SI vector type without explicit casts.  In order to fix this, we need to
> use a different otherwise unused vector type for the opaque vector type.
> Nick started on a patch to do this, but didn't have enough time to finish it.

This shouldn't be done at the RTL level at all; the right thing to do
is to create a special '__ev64_opaque__' type which is different from
'vector int' and just happens to also have V2SImode (or DImode or
whatever is convenient---I'd vote for DImode since that's what GCC
uses for all-purpose "blob of data" types).

-- 
- Geoffrey Keating <geoffk@geoffk.org>