Speed up implicit resolution by avoiding allocations when traversing TypeRefs in core #7012
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milessabin
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| case TypeRef(pre, sym, args) => | ||
| val coreArgs = args.mapConserve(core) | ||
| if (coreArgs eq args) tp | ||
| else typeRef(pre, sym, coreArgs) |
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Would tp.mapOver(this) also do the trick?
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It might if core was reworked as a TypeMap, but I don't think that would be right here. In particular mapOver also transforms the prefix which I don't think we want to do.
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Mapping over the prefix increases the compile time for the benchmark from 25s to 35s on my machine, so I'd say that's a definite no.
adriaanm
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As reported here, #6530 causes a significant slowdown when performing implicit searches for large types: in the case of the "select from large hlist" benchmark it roughly doubles the compile time.
This PR claws almost all of that back by avoiding allocations when traversing through TypeRefs.