Various performance optimizations #3214
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When `Stats.enabled` is false, `Stats.record` should be free, but before
this commit this wasn't the case: since the `n` passed to `record` was
by-value, it had to be evaluated, this is very expensive for calls like:
record("retained typed trees after typer", unit.tpdTree.treeSize)
Before this commit, we got after inlining:
val n = unit.tpdTree.treeSize
Now we get:
def n = unit.tpdTree.treeSize
it'd be even nicer if we didn't generate anything at all, but this
shouldn't have much impact on running time.
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(I found this performance issue by using https://github.com/jvm-profiling-tools/async-profiler) |
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test performance please |
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performance test scheduled: 1 job(s) in queue, 0 running. |
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Performance test finished successfully: Visit http://dotty-bench.epfl.ch/3214/ to see the changes. Benchmarks is based on merge(s) with master |
smarter
changed the title
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I went ahead and did some more optimizations while I was at it :). |
Using "%" to find the index of an entry in the backing array is expensive, by restricting our backing array size to be a power of two we can use "&" instead. This is similar to what we do in the implementation of MutableScope (note: should we try to avoid code duplication between util.HashSet and MutableScope?).
This showed up while doing some CPU profiling,
smarter
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Performance test finished successfully: Visit http://dotty-bench.epfl.ch/3214/ to see the changes. Benchmarks is based on merge(s) with master |
| i -= 1 | ||
| } | ||
| hasRedefinedMethod(cls.getSuperclass, name) | ||
| } |
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I wonder why this method shows up as hot. It should only be called during initialization when we compute the tree transformers. How often is the method called? Back of the envelope calculation: 100 phases * 50 methods, i.e. 5000? If its significantly more than that there's something we have overlooked.
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| @inline | |||
| def record(fn: String, n: Int = 1) = | |||
| def record(fn: => String, n: => Int = 1) = | |||
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One can do even better by using two overloaded versions of record and no default argument.
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I don't see how, could you give more details?
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