0edb084f9d
Paul's original code had emit_control_data_bits() skip the URB write if vertex_count was 0. This meant wrapping every control data write in a conditional write. We accumulate control data bits in a single UD (32-bit) register. For simple shaders that don't emit many vertices, the control data header will be <= 32-bits long, so we only need to write it once at the end of the shader. For shaders with larger headers, we write out batches of control data bits at EmitVertex(), when (vertex_count * bits_per_vertex) % 32 == 0. On the first EmitVertex() call, the above expression will evaluate to true simply because vertex_count == 0. But we want to avoid emitting the control data bits, because we haven't accumulated 32-bits worth yet. In other words, the vertex_count != 0 check is really only necessary in the EmitVertex() batching case, not the end-of-thread case. This saves a CMP/IF/ENDIF in every shader that uses EndPrimitive() or multiple streams. The only downside is that a shader which emits no vertices at all will execute an additional URB write---but such shaders are pointless and not worth optimizing. Signed-off-by: Kenneth Graunke <kenneth@whitecape.org> Reviewed-by: Matt Turner <mattst88@gmail.com> |
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| loader | ||
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| util | ||
| Makefile.am | ||
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