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spirv: Eliminate dead input/output variables after translation.

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spirv_to_nir can generate input/output variables which are illegal
for the current shader stage, which would cause nir_validate_shader
to balk.  After my recent commit to start decorating arrays as compact,
dEQP-VK.spirv_assembly.instruction.graphics.module.same_module started
hitting validation errors due to outputs in a TCS (not intended for the
TCS at all) not being per-vertex arrays.

Thanks to Jason Ekstrand for suggesting this approach.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109573
Fixes: ef99f4c8d1 compiler: Mark clip/cull distance arrays as compact before lowering.
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
(cherry picked from commit 6775665e5e)
This commit is contained in:
Kenneth Graunke 2019-02-06 16:45:25 -08:00 • committed by Dylan Baker
parent bdc946c23a
commit a4ea63e884
1 changed files with 20 additions and 5 deletions
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25
src/compiler/spirv/spirv_to_nir.c
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@ -4481,20 +4481,35 @@ spirv_to_nir(const uint32_t *words, size_t word_count,
}
} while (progress);
vtn_assert(b->entry_point->value_type == vtn_value_type_function);
nir_function *entry_point = b->entry_point->func->impl->function;
vtn_assert(entry_point);
entry_point->is_entrypoint = true;
/* When multiple shader stages exist in the same SPIR-V module, we
* generate input and output variables for every stage, in the same
* NIR program. These dead variables can be invalid NIR. For example,
* TCS outputs must be per-vertex arrays (or decorated 'patch'), while
* VS output variables wouldn't be.
*
* To ensure we have valid NIR, we eliminate any dead inputs and outputs
* right away. In order to do so, we must lower any constant initializers
* on outputs so nir_remove_dead_variables sees that they're written to.
*/
nir_lower_constant_initializers(b->shader, nir_var_shader_out);
nir_remove_dead_variables(b->shader,
nir_var_shader_in | nir_var_shader_out);
/* We sometimes generate bogus derefs that, while never used, give the
* validator a bit of heartburn. Run dead code to get rid of them.
*/
nir_opt_dce(b->shader);
vtn_assert(b->entry_point->value_type == vtn_value_type_function);
nir_function *entry_point = b->entry_point->func->impl->function;
vtn_assert(entry_point);
/* Unparent the shader from the vtn_builder before we delete the builder */
ralloc_steal(NULL, b->shader);
ralloc_free(b);
entry_point->is_entrypoint = true;
return entry_point;
}