Remove the modulo operations in spsc#652
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These modulo operations used to be well optimized when N was a power of 2 However, the consumer and producer now use view-types that make N runtime dependant, preventing the compiler from optimizing these modulo operations even when N is always a power of 2. This patch leverages the fact that `head` and `tail` are always kept lower than N to replace the modulo operations with a simple if, which gets optimized pretty well by the compiler and no branch is left. Closes rust-embedded#650
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I wish we had some benchmarking infra in place. This would help me make sure this actually solves the problem and would have helped detect it in the first place. |
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Clippy lint fixes are already included in #644 |
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@823984418 does this fix your performance issues? |
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These modulo operations used to be well optimized when N was a power of 2 However, the consumer and producer now use view-types that make N runtime dependant, preventing the compiler from optimizing these modulo operations even when N is always a power of 2.
This patch leverages the fact that
headandtailare always kept lower than N to replace the modulo operations with a simple if, which gets optimized pretty well by the compiler and no branch is left.Closes #650