[Mesa-dev] [PATCH 03/11] st/mesa: implement GL_ATI_fragment_shader

[Miklós Máté]

On 12/16/2015 11:40 PM, Ilia Mirkin wrote:
> On Tue, Dec 15, 2015 at 6:05 PM, Miklós Máté <mtmkls at gmail.com> wrote:
>> +   } else if (desc->special == 3) {
>> +      src[0] = args[0];
>> +      src[1] = args[1];
>> +      src[2] = ureg_swizzle(args[2],
>> +            TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z, TGSI_SWIZZLE_Z);
>> +      emit_insn(t, TGSI_OPCODE_DP2A, dst, 1, src, 3);
>> +   }
> Not strictly your fault, but in practice, no backends actually
> implement DP2A. Not sure why -- i915, nv30, and r300 even have
> explicit ops for this. You can use DP2 + ADD. Or go around all the
> backends an implement it.
>
>    -ilia
Actually, I wanted to ask what this opcode is useful for, because I have 
no clue. I'll change it to DP2+ADD for the next version.

By the way, I found no example that used any of these three special 
ATIfs instructions.

MM