[Mesa-dev] [PATCH mesa v2 3/3] nouveau: codegen: LOAD: Take src swizzle into account

[Hans de Goede]

Hi,

On 22-04-16 09:08, Marek Olšák wrote:
> On Thu, Apr 21, 2016 at 7:04 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> [+radeon folk]
>>
>> Marek, Nicolai, Bas - please have a look at the doc change and let us
>> know if you think this will cause a problem for radeon.
>>
>> Hans is solving the issue that he wants to swizzle the data loaded
>> from the image/buffer/whatever before sticking it into the dst
>> register.
>
> Is this something st/mesa needs or just nouveau? If just nouveau needs
> it, I don't see a point in updating the TGSI spec, since nouveau can
> just add the swizzle when translating from TGSI.

This is something which the llvm tgsi backend needs, which we plan to
use to add opencl support to nouveau.

 From the commit msg:

"The llvm TGSI backend uses pointers in registers and does things like:

LOAD TEMP[0].y, MEMORY[0], TEMP[0]

Expecting the data at address TEMP[0].x to get loaded to
TEMP[0].y. But this will cause the data at TEMP[0].x + 4 to be
loaded instead.

This commit adds support for a swizzle suffix for the 1st source
operand, which allows using:

LOAD TEMP[0].y, MEMORY[0].xxxx, TEMP[0]

And actually getting the desired behavior"

Regards,

Hans