[Impeller] Cache location in metadata. #46640
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impeller/core/shader_types.h
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| /// the OpenGLES backend. | ||
| /// | ||
| /// See buffer_binding_gles.cc. | ||
| mutable std::optional<int> location = std::nullopt; |
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This seems fine to me. But when this was written, the metadata was meant to be static const. So I am not sure about the lifecycle of this. I am also worried (perhaps incorrectly) about interactive with multiple OpenGL drivers at some point in the future.
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From Triage: lets just store it in the "PSO" instead.
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I've updated this to cache the binding data in in the buffer_binding, I couldn't put them in the pipeline itself as that doesn't actually have all of the information needed. To support this I made the buffer_binding pointer non-const. So we still use one hashmap lookup per shader, but the key we use is already generated on the shader metadata so its less work. |
chinmaygarde
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chinmaygarde
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I couldn't tell what information was missing to put this in the pipeline state object. But this is an improvement for sure.
| for (auto i = 0u; i < metadata->members.size(); i++) { | ||
| const auto& member = metadata->members[i]; | ||
| auto location = locations[i]; | ||
| if (location == -1) { |
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Preserve the comment about inactive uniformed being optimized out?
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Oh, I see it up top. Maybe just "void type or inactive".
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The BufferBinding is essentially part of the PSO, so its all approximately the same, right 😄 |
jonahwilliams
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Hacky mutable stuff, but avoids recomputing string keys and hashing them multiple times per draw call. See also
While we cache the uniform location, looking up this value requires computing a string key for every single uniform value on every single command. We can speed this up by stashing the uniform location in the shader metadata, which shouldn't change for the app lifetime. This avoids both the string computation and the hashmap usage.