rfc: auto-casted vector types

[Kumar Gala]

The SPE PIM docs are not currently publicly available.

- kumar

On Monday, February 17, 2003, at 04:25 PM, Jim Wilson wrote:

> Aldy Hernandez <aldyh@redhat.com> writes:
>
>> The PPC E500 API specifies that vector types of type __ev64_opaque__
>> (V2SImode) can interconvert with other vector types without a cast.
>
> Is there any publicly available documentation?  My copy of the draft 
> docs
> say they are Motorola confidential.  If there is documentation 
> available,
> it would be useful to point to it somewhere.
>
> I tried searching the Motorola web site.  I found Altivec PIM 
> documentation,
> but no SPE PIM documentation.
>
>> 	* doc/tm.texi: Document TARGET_VECTOR_TYPES_COMPATIBLE.
>> 	* c-typeck.c (comptypes): Take into account
>> 	TARGET_VECTOR_TYPES_COMPATIBLE.
>> 	(convert_for_assignment): Same.
>>       ...
>
> The patch looks pretty reasonable to me also.  I agree with Zack's 
> suggestions.
>
> 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.
>
> Jim