[Mesa-dev] [RFC 2/2] i965: add support for image AoA

Francisco Jerez currojerez at riseup.net
Sat Aug 15 07:33:09 PDT 2015


Timothy Arceri <t_arceri at yahoo.com.au> writes:

> On Wed, 2015-08-12 at 19:39 +1000, Timothy Arceri wrote:
>> Cc: Francisco Jerez <currojerez at riseup.net>
>> ---
>>  This patch works for direct indexing of images, but I'm having some trouble
>>  getting indirect to work.
>> 
>>  For example for:
>>  tests/spec/arb_arrays_of_arrays/execution/image_store/basic-imageStore
>>  -non-const-uniform-index.shader_test
>> 
>>  Which has and image writeonly uniform image2D tex[2][2]
>> 
>>  Indirect indexing will work for tex[0][0] and text[0][1] but not for
>>  tex[1][0] and tex[1][1] they seem to always end up refering to the
>>  image in 0.
>
> Just to add some more to this, I'm pretty sure my code is generating the
> correct offsets. If I hardcode the img_offset offset to 72 to get the uniform
> value of tex[1][0] I get the value I expected, but if I set image.reladdr to a
> register that contains 72 I don't what I expect.
>
> If I change the array to be a single dimension e.g. tex[4] and I hardcode the
> offset as described above then it works as expected for both scenarios, it
> also works if I split the offset across img_offset and image.reladdr, there is
> something going on with image.reladdr for multi-dimensional arrays that I can'
> t quite put my finger on.
>
> Any hints appreciated.
>
Odd, can you attach an assembly dump?

Thanks.

>
>> 
>>  I can't quite seem to see either my mistake or what I'm missing so I 
>> thought
>>  I'd send this out, and see if anyone has any ideas. I've also sent some
>>  tests with mixed direct/indirect indexing which seem to calculate the 
>> correct
>>  offest for the direct but the indirect indexing is not working there 
>> either. 
>> 
>>  src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 53 ++++++++++++++++++++++-------
>> ---
>>  1 file changed, 36 insertions(+), 17 deletions(-)
>> 
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp 
>> b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> index d7a2500..a49c230 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> @@ -226,6 +226,7 @@ fs_visitor::nir_setup_uniform(nir_variable *var)
>>        * our name.
>>        */
>>     unsigned index = var->data.driver_location;
>> +   bool set_image_location = true;
>>     for (unsigned u = 0; u < shader_prog->NumUniformStorage; u++) {
>>        struct gl_uniform_storage *storage = &shader_prog->UniformStorage[u];
>>  
>> @@ -244,7 +245,13 @@ fs_visitor::nir_setup_uniform(nir_variable *var)
>>            * because their size is driver-specific, so we need to allocate
>>            * space for them here at the end of the parameter array.
>>            */
>> -         var->data.driver_location = uniforms;
>> +         if (set_image_location) {
>> +            /* For arrays of arrays we only want to set this once at the 
>> base
>> +             * location.
>> +             */
>> +            var->data.driver_location = uniforms;
>> +            set_image_location = false;
>> +         }
>>           param_size[uniforms] =
>>              BRW_IMAGE_PARAM_SIZE * MAX2(storage->array_elements, 1);
>>  
>> @@ -1165,19 +1172,27 @@ fs_visitor::get_nir_image_deref(const nir_deref_var 
>> *deref)
>>  {
>>     fs_reg image(UNIFORM, deref->var->data.driver_location,
>>                  BRW_REGISTER_TYPE_UD);
>> -
>> -   if (deref->deref.child) {
>> -      const nir_deref_array *deref_array =
>> -         nir_deref_as_array(deref->deref.child);
>> -      assert(deref->deref.child->deref_type == nir_deref_type_array &&
>> -             deref_array->deref.child == NULL);
>> -      const unsigned size = glsl_get_length(deref->var->type);
>> +   fs_reg *indirect_offset = NULL;
>> +
>> +   unsigned img_offset = 0;
>> +   const nir_deref *tail = &deref->deref;
>> +   while (tail->child) {
>> +      const nir_deref_array *deref_array = nir_deref_as_array(tail->child);
>> +      assert(tail->child->deref_type == nir_deref_type_array);
>> +      tail = tail->child;
>> +      const unsigned size = glsl_get_length(tail->type);
>> +      const unsigned child_array_elements = tail->child != NULL ?
>> +         glsl_get_aoa_size(tail->type) : 1;
>>        const unsigned base = MIN2(deref_array->base_offset, size - 1);
>> -
>> -      image = offset(image, bld, base * BRW_IMAGE_PARAM_SIZE);
>> +      const unsigned aoa_size = child_array_elements * 
>> BRW_IMAGE_PARAM_SIZE;
>> +      img_offset += base * aoa_size;
>>  
>>        if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
>> -         fs_reg *tmp = new(mem_ctx) fs_reg(vgrf(glsl_type::int_type));
>> +         fs_reg tmp = vgrf(glsl_type::int_type);
>> +         if (indirect_offset == NULL) {
>> +            indirect_offset = new(mem_ctx) 
>> fs_reg(vgrf(glsl_type::int_type));
>> +            bld.MOV(*indirect_offset, fs_reg(0));
>> +         }
>>  
>>           if (devinfo->gen == 7 && !devinfo->is_haswell) {
>>              /* IVB hangs when trying to access an invalid surface index 
>> with
>> @@ -1188,18 +1203,22 @@ fs_visitor::get_nir_image_deref(const nir_deref_var 
>> *deref)
>>               * of the possible outcomes of the hang.  Clamp the index to
>>               * prevent access outside of the array bounds.
>>               */
>> -            bld.emit_minmax(*tmp, retype(get_nir_src(deref_array
>> ->indirect),
>> -                                         BRW_REGISTER_TYPE_UD),
>> +            bld.emit_minmax(tmp, retype(get_nir_src(deref_array->indirect),
>> +                                        BRW_REGISTER_TYPE_UD),
>>                              fs_reg(size - base - 1), BRW_CONDITIONAL_L);
>>           } else {
>> -            bld.MOV(*tmp, get_nir_src(deref_array->indirect));
>> +            bld.MOV(tmp, get_nir_src(deref_array->indirect));
>>           }
>> -
>> -         bld.MUL(*tmp, *tmp, fs_reg(BRW_IMAGE_PARAM_SIZE));
>> -         image.reladdr = tmp;
>> +         bld.MUL(tmp, tmp, fs_reg(aoa_size));
>> +         bld.ADD(*indirect_offset, *indirect_offset, tmp);
>>        }
>>     }
>>  
>> +   if (indirect_offset) {
>> +      image.reladdr = indirect_offset;
>> +   }
>> +   image = offset(image, bld, img_offset);
>> +
>>     return image;
>>  }
>>  
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