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v3dv/pipeline: use derefs for ubo/ssbo 

There are some potential advantages for that. Even if we are not
taking advantage of them, it would be interesting to be using this
path now, specially as non-deref path could be removed at some point.

Note that instead of returning for both resource_index and
vulkan_descriptor a vec2, we return a scalar for the first one, as it
is what the v3d backend expect (like for get_ssbo_size). For this to
work, we reconfigure the vec2 at vulkan_descriptor using the index and
an unused 0 value.

As far as I see turnip avoids that by lowering too load_ssbo/ubo, so
it just gets the index lowered (that in their case it is a vec3 with a
fixed 0 on the third component), but for now it is easier doing this.

v2: return a single-component for the index, to avoid the backend
    needing to handle it (Eric, Jason).

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>
This commit is contained in:
Alejandro Piñeiro 2020-08-12 23:35:04 +02:00 committed by Marge Bot
parent 17c5a09c85
commit 8f0696781f
1 changed files with 21 additions and 0 deletions
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21
src/broadcom/vulkan/v3dv_pipeline.c
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@ -366,6 +366,10 @@ preprocess_nir(nir_shader *nir,
});
}
NIR_PASS_V(nir, nir_lower_explicit_io,
nir_var_mem_ubo | nir_var_mem_ssbo,
nir_address_format_32bit_index_offset);
NIR_PASS_V(nir, nir_remove_dead_variables, nir_var_shader_in |
nir_var_shader_out | nir_var_system_value | nir_var_mem_shared,
NULL);
@ -611,6 +615,12 @@ lower_vulkan_resource_index(nir_builder *b,
break;
}
/* Since we use the deref pass, both vulkan_resource_index and
* vulkan_load_descriptor returns a vec2. But for the index the backend
* expect just one scalar (like with get_ssbo_size), so lets return here
* just it. Then on load_descriptor we would recreate the vec2, keeping the
* second component (unused right now) to zero.
*/
nir_ssa_def_rewrite_uses(&instr->dest.ssa,
nir_src_for_ssa(nir_imm_int(b, index)));
nir_instr_remove(&instr->instr);
@ -861,6 +871,17 @@ lower_intrinsic(nir_builder *b, nir_intrinsic_instr *instr,
lower_vulkan_resource_index(b, instr, pipeline, layout);
return true;
case nir_intrinsic_load_vulkan_descriptor: {
/* We are not using it, as loading the descriptor happens as part of the
* load/store instruction, so the simpler is just doing a no-op. We just
* lower the desc back to a vec2, as it is what load_ssbo/ubo expects.
*/
nir_ssa_def *desc = nir_vec2(b, instr->src[0].ssa, nir_imm_int(b, 0));
nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(desc));
nir_instr_remove(&instr->instr);
return true;
}
case nir_intrinsic_image_deref_load:
case nir_intrinsic_image_deref_store:
case nir_intrinsic_image_deref_atomic_add: