maps,runtime: improve maps.Clone
name old time/op new time/op delta
MapClone-10 65.8ms ± 7% 10.3ms ± 2% -84.30% (p=0.000 n=10+9)
name old alloc/op new alloc/op delta
MapClone-10 40.2MB ± 0% 40.5MB ± 0% +0.57% (p=0.000 n=10+9)
name old allocs/op new allocs/op delta
MapClone-10 20.0 ± 0% 23.0 ± 0% +15.00% (p=0.000 n=10+10)
Updates #58740.
Change-Id: I148501e723cb2124f02045400e7ceb36af0871c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/471400
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: xie cui <
523516579@qq.com>
Reviewed-by: Keith Randall <khr@google.com>