[cfe-dev] Casting scalars to vectors

[Eli Friedman]

On Mon, Apr 19, 2010 at 3:00 PM, John Thompson
<john.thompson.jtsoftware at gmail.com> wrote:
> My colleague pointed out that it's not a cast, but a literal, which Clang
> should support.

I'm pretty sure that's already implemented... are you passing
-faltivec to clang?

-Eli

> -John
>
> On Mon, Apr 19, 2010 at 11:45 AM, John Thompson
> <john.thompson.jtsoftware at gmail.com> wrote:
>>
>> According to the AltiVec standard (section 2.4.6 in
>> http://www.freescale.com/files/32bit/doc/ref_manual/ALTIVECPIM.pdf), casting
>> a scalar to a vector is illegal, yet gcc seems to support it, as seen in
>> many of those little files in the PS3 SDK in target\ppu\include\bits, which
>> have statements like:
>>
>> vec_uint4 mask = (vec_uint4)(vec_int4)(-1);
>>
>> where vec_uint4 and vec_int4 are typedefs for vector types, i.e.:
>>
>> typedef vector int vec_int4;
>>
>> What does this actually do? I'm guessing it's supposed to fill the vector
>> components with -1.
>>
>> How should this be handled in Clang?
>>
>> I filed a Bugzilla bug 6846 on this.
>>
>> If Clang should support it
>> , I might be able to take a crack at it, with a little guidance.
>>
>> --
>> John Thompson
>> John.Thompson.JTSoftware at gmail.com
>>
>
>
>
> --
> John Thompson
> John.Thompson.JTSoftware at gmail.com
>
>
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