commit | aee71dd70b3779c66950ce6a952deca13d48e55e | [log] [tgz] |
---|---|---|
author | Martin Möhrmann <moehrmann@google.com> | Fri Apr 27 21:58:59 2018 +0200 |
committer | Martin Möhrmann <moehrmann@google.com> | Tue May 08 21:15:16 2018 +0000 |
tree | ba5e077b2478755d5a423c9898c23b9bd3819cdd | |
parent | cd1976dbef0a4a474cccb9e7fcb1e9cf2310df66 [diff] |
cmd/compile: optimize map-clearing range idiom replace map clears of the form: for k := range m { delete(m, k) } (where m is map with key type that is reflexive for ==) with a new runtime function that clears the maps backing array with a memclr and reinitializes the hmap struct. Map key types that for example contain floats are not replaced by this optimization since NaN keys cannot be deleted from maps using delete. name old time/op new time/op delta GoMapClear/Reflexive/1 92.2ns ± 1% 47.1ns ± 2% -48.89% (p=0.000 n=9+9) GoMapClear/Reflexive/10 108ns ± 1% 48ns ± 2% -55.68% (p=0.000 n=10+10) GoMapClear/Reflexive/100 303ns ± 2% 110ns ± 3% -63.56% (p=0.000 n=10+10) GoMapClear/Reflexive/1000 3.58µs ± 3% 1.23µs ± 2% -65.49% (p=0.000 n=9+10) GoMapClear/Reflexive/10000 28.2µs ± 3% 10.3µs ± 2% -63.55% (p=0.000 n=9+10) GoMapClear/NonReflexive/1 121ns ± 2% 124ns ± 7% ~ (p=0.097 n=10+10) GoMapClear/NonReflexive/10 137ns ± 2% 139ns ± 3% +1.53% (p=0.033 n=10+10) GoMapClear/NonReflexive/100 331ns ± 3% 334ns ± 2% ~ (p=0.342 n=10+10) GoMapClear/NonReflexive/1000 3.64µs ± 3% 3.64µs ± 2% ~ (p=0.887 n=9+10) GoMapClear/NonReflexive/10000 28.1µs ± 2% 28.4µs ± 3% ~ (p=0.247 n=10+10) Fixes #20138 Change-Id: I181332a8ef434a4f0d89659f492d8711db3f3213 Reviewed-on: https://go-review.googlesource.com/110055 Reviewed-by: Keith Randall <khr@golang.org>
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