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runtime: special case interface hashing for pointers

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Interfaces often contain pointers. Implement a fast path for this case.

name                   old time/op  new time/op  delta
MapInterfaceString-16  21.4ns ±19%  20.5ns ±10%     ~     (p=0.361 n=10+10)
MapInterfacePtr-16     25.8ns ± 8%  17.3ns ± 7%  -33.11%  (p=0.000 n=10+9)

Fixes #37086

Change-Id: Ice52820e6259a3edeafcbbbeb25b1e363bef00d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/219338
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Keith Randall 2020-02-13 08:34:41 -08:00
parent 1c0d664128
commit afd691c579
1 changed files with 9 additions and 1 deletions
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10
src/runtime/alg.go
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@ -160,7 +160,15 @@ func nilinterhash(p unsafe.Pointer, h uintptr) uintptr {
// maps generated by reflect.MapOf (reflect_typehash, below).
func typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr {
if t.tflag&tflagRegularMemory != 0 {
return memhash(p, h, t.size)
// Handle ptr sizes specially, see issue 37086.
switch t.size {
case 4:
return memhash32(p, h)
case 8:
return memhash64(p, h)
default:
return memhash(p, h, t.size)
}
}
switch t.kind & kindMask {
case kindFloat32: