[Mesa-dev] [PATCH v4 (part2) 17/59] i965/fs/nir: implement unsized array's length calculation

[Samuel Iglesias Gonsálvez]

On 29/08/15 00:22, Jordan Justen wrote:
> On 2015-08-05 01:30:14, Iago Toral Quiroga wrote:
>> From: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
>>
>> Signed-off-by: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
>> ---
>>  src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 49 ++++++++++++++++++++++++++++++++
>>  1 file changed, 49 insertions(+)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> index e922a85..fde65e9 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> @@ -1578,6 +1578,55 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
>>        emit_barrier();
>>        break;
>>  
>> +   case nir_intrinsic_ssbo_unsized_array_length: {
>> +      nir_const_value *const_uniform_block = nir_src_as_const_value(instr->src[0]);
>> +      unsigned ubo_index = const_uniform_block ? const_uniform_block->u[0] : 0;
>> +      nir_const_value *const_offset_ir = nir_src_as_const_value(instr->src[1]);
>> +      int const_offset = const_offset_ir ? const_offset_ir->u[0] : 0;
>> +      nir_const_value *const_stride_ir = nir_src_as_const_value(instr->src[2]);
>> +      unsigned unsized_array_stride = const_stride_ir ? const_stride_ir->u[0] : 1;
>> +      int reg_width = dispatch_width / 8;
>> +
>> +      assert(shader->base.UniformBlocks[ubo_index].IsShaderStorage);
>> +
>> +      /* Set LOD = 0 */
>> +      fs_reg source = fs_reg(0);
>> +
>> +      int mlen = 1 * reg_width;
>> +      fs_reg src_payload = fs_reg(GRF, alloc.allocate(mlen),
>> +                                  BRW_REGISTER_TYPE_UD);
>> +      bld.LOAD_PAYLOAD(src_payload, &source, 1, 0);
>> +
>> +      fs_reg surf_index = fs_reg(prog_data->binding_table.ubo_start + ubo_index);
>> +      fs_reg buffer_size = vgrf(glsl_type::int_type);
>> +
>> +      fs_inst *inst = bld.emit(FS_OPCODE_UNSIZED_ARRAY_LENGTH, buffer_size,
>> +                               src_payload, surf_index);
> 
> Just noting that you plan to rename this op-code...
> 

Right

>> +      inst->header_size = 0;
>> +      inst->mlen = mlen;
>> +      inst->regs_written = 4 * reg_width;
>> +      bld.emit(inst);
>> +
>> +      /* array.length() =
>> +          max((buffer_object_size - offset_of_array) / stride_of_array, 0) */
> 
> Add '*' at the front of each multi-line comment.
> 

OK

>> +      fs_reg temp = vgrf(glsl_type::float_type);
>> +      bld.ADD(buffer_size, buffer_size, fs_reg(-const_offset));
>> +      bld.MOV(temp, buffer_size);
>> +
>> +      assert(unsized_array_stride > 0);
>> +
>> +      fs_reg stride = fs_reg((float)1/unsized_array_stride);
>> +      bld.MUL(temp, temp, stride);
> 
>> +      bld.MOV(dest, fs_reg(0));
>> +      bld.CMP(bld.null_reg_f(), temp, fs_reg(0), BRW_CONDITIONAL_G);
>> +      bld.IF(BRW_PREDICATE_NORMAL);
>> +      {
>> +         bld.MOV(retype(dest, BRW_REGISTER_TYPE_D), temp);
>> +      }
>> +      bld.emit(BRW_OPCODE_ENDIF);
> 
> I think you can use bld.emit_minmax for this block.
> 
> Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>

This commit will change. I am modifying the unsized array length patches
to do the calculation at mesa core level, so the drivers don't need to
implement the formula by themselves.

Basically, the code from "/* array.length() " to here is going to be
moved to mesa core.

I can keep your R-b, as the rest of the patch will be same... or wait
for your review of the new version, as you prefer.

Sam

> 
>> +      break;
>> +   }
>> +
>>     default:
>>        unreachable("unknown intrinsic");
>>     }
>> -- 
>> 1.9.1
>>
>