Iago Toral Quiroga
d19ce36ff2
Until now, if we can't compile at 4 threads we would lower thread count with optimizations disabled, however, lowering thread count doubles the amount of registers available per thread, so that alone is already a big relief for register pressure so it makes sense to enable optimizations when we do that, and progressively disable them until we enable spilling as a last resort. This can slightly improve performance for some applications. Sponza, for example, gets a ~1.5% boost. I see several UE4 shaders that also get compiled to better code at 2 threads with this, but it is more difficult to assess how much this improves performance in practice due to the large variance in frame times that we observe with UE4 demos. Also, if a compiler strategy disables an optimization that did not make any progress in the previous compile attempt, we would end up re-compiling the exact same shader code and failing again. This, patch keeps track of which strategies won't make progress and skips them in that case to save some CPU time during shader compiles. Care should be taken to ensure that we try to compile with the default NIR scheduler at minimum thread count at least once though, so a specific strategy for this is added, to prevent the scenario where no optimizations are used and we skip directly to the fallback scheduler if the default strategy fails at 4 threads. Similarly, we now also explicitly specify which strategies are allowed to do TMU spills and make sure we take this into account when deciding to skip strategies. This prevents the case where no optimizations are used in a shader and we skip directly to the fallback scheduler after failing compilation at 2 threads with the default NIR scheduler but without trying to spill first. Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10647>
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