[Mesa-dev] [PATCH 2/9] radeonsi: use V_BFE for extracting a sample index

[Marek Olšák]

On Mon, Mar 2, 2015 at 10:05 PM, Tom Stellard <tom at stellard.net> wrote:
> On Mon, Mar 02, 2015 at 12:54:16PM +0100, Marek Olšák wrote:
>> From: Marek Olšák <marek.olsak at amd.com>
>>
>> ---
>>  src/gallium/drivers/radeonsi/si_shader.c | 22 ++++++++++++++++------
>>  1 file changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
>> index b0417ed..f125483 100644
>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>> @@ -192,6 +192,20 @@ static int get_param_index(unsigned semantic_name, unsigned index,
>>  }
>>
>>  /**
>> + * BitField Extract: ((value >> rshift) & ((1 << bitwidth) - 1))
>> + */
>
> Ideally, we would just add a pattern for this in the backend and emit generic
> LLVM IR here.  This would also make it possible to share the code with llvmpipe.
>
> I think the best place to do this would be in AMDGPUTargetLowering::performDAGCombine().

Why not SIInstructions.td?

Marek