[Mesa-dev] [PATCH 14/20] radeonsi: reserve a parameter slot for FMASK resources in shaders

[Christian König]

Am 08.08.2013 10:30, schrieb Michel Dänzer:
> On Don, 2013-08-08 at 02:20 +0200, Marek Olšák wrote:
>> diff --git a/src/gallium/drivers/radeonsi/si_state_draw.c b/src/gallium/drivers/radeonsi/si_state_draw.c
>> index 746ace6..4208fa7 100644
>> --- a/src/gallium/drivers/radeonsi/si_state_draw.c
>> +++ b/src/gallium/drivers/radeonsi/si_state_draw.c
>> @@ -241,6 +241,7 @@ static void si_pipe_shader_ps(struct pipe_context *ctx, struct si_pipe_shader *s
>>   		/* Last 2 reserved SGPRs are used for VCC */
>>   		num_sgprs = num_user_sgprs + 2;
>>   	}
>> +	num_sgprs += 1; /* XXX this fixes VM faults */
>>   	assert(num_sgprs <= 104);
> You can't just increment num_sgprs unconditionally here, or the
> assertion will spuriously fail again when num_sgprs was 104 to begin
> with.
>
> More fundamentally, I'd really like us to understand why / under what
> circumstances the value needs to be incremented at all. You mentioned on
> IRC that you were using an LLVM 3.3 tree, is this change still necessary
> with LLVM master / trunk? If yes, it would be good to look into at least
> some example shaders where the change is really necessary, to try and
> understand the circumstances.

Additional to that I'm not sure if we should add another sgpr pointer to 
the shader, the docs speak of quite a performance penalty for each. 
Since they are (optional) attributes to the textures anyway they could 
probably be interleaved with the texture resources.

Christian.