[Mesa-dev] [PATCH 4/5] i965/vs: Add support for shadow comparitors with gather4

[Chris Forbes]

You're right, that looks completely bogus.

I only have compiler tests and eyeballs for the shadow variants at
this point -- I'll sort that out :)

-- Chris

On Fri, Oct 11, 2013 at 9:33 AM, Eric Anholt <eric at anholt.net> wrote:
> Chris Forbes <chrisf at ijw.co.nz> writes:
>
>> gather4_c's argument layout is straightforward -- refz just goes on the
>> end.
>>
>> gather4_po_c's layout however -- the array index is replaced with refz.
>>
>> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
>
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
>> index 20221d9..7aa8368 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
>> @@ -2341,7 +2341,7 @@ vec4_visitor::visit(ir_texture *ir)
>>                    src_reg(0)));
>>        }
>>        /* Load the shadow comparitor */
>> -      if (ir->shadow_comparitor && ir->op != ir_txd) {
>> +      if (ir->shadow_comparitor && ir->op != ir_txd && (ir->op != ir_tg4 || !has_nonconstant_offset)) {
>>        emit(MOV(dst_reg(MRF, param_base + 1, ir->shadow_comparitor->type,
>>                         WRITEMASK_X),
>>                 shadow_comparitor));
>> @@ -2406,9 +2406,18 @@ vec4_visitor::visit(ir_texture *ir)
>>           inst->mlen += 2;
>>        }
>>        } else if (ir->op == ir_tg4 && has_nonconstant_offset) {
>> -         emit(MOV(dst_reg(MRF, param_base + 1, glsl_type::ivec2_type, WRITEMASK_XY),
>> -                  offset_value));
>> -         inst->mlen++;
>> +         if (ir->shadow_comparitor) {
>> +            emit(MOV(dst_reg(MRF, param_base + 1,
>> +                             ir->shadow_comparitor->type, WRITEMASK_X),
>> +                     shadow_comparitor));
>> +            emit(MOV(dst_reg(MRF, param_base + 1, glsl_type::ivec2_type, WRITEMASK_YZ),
>> +                     offset_value));
>> +            inst->mlen++;
>> +         } else {
>> +            emit(MOV(dst_reg(MRF, param_base + 1, glsl_type::ivec2_type, WRITEMASK_XY),
>> +                     offset_value));
>> +            inst->mlen++;
>> +         }
>>        }
>>     }
>
> I don't think this code ends up working out.  I'm looking at the 4x2
> tables and I see:
>
>               0.x  0.y  0.z  0.w   1.x   1.y  1.z  1.w
> sample_c:     u    v    r    ai    ref
> sample_po_c:  u    v    r    ref   offu  offv
>
> You're writing the shadow comparitor to 1.x instead of 0.w, and the
> offset to 1.yz instead of 1.xy.
>
> Are there tests for these cases?