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| author | Martin Möhrmann <moehrmann@google.com> | 2017-09-06 08:36:10 +0200 |
|---|---|---|
| committer | Martin Möhrmann <moehrmann@google.com> | 2017-09-07 06:34:12 +0000 |
| commit | ec0e2edd3b8e92ca003416a4cdbd9b7345d9d38f (patch) | |
| tree | 8597f1280f87ec0d5c3afec951faffc0802c9afc /src | |
| parent | 4410900a3cf4477fc91b3a09cadd215cc0fe8d3a (diff) | |
| download | go-ec0e2edd3b8e92ca003416a4cdbd9b7345d9d38f.tar.xz | |
runtime: avoid extra tophash check in mapassign when key comparison is cheap
mapaccess and mapdelete functions are already optimized to prefer direct
key comparison instead of tophash checks when key comparison is cheap.
Extended version of golang.org/cl/55235.
AMD64:
name old time/op new time/op delta
MapPopulate/1 42.5ns ± 2% 40.3ns ± 2% -5.37% (p=0.000 n=9+10)
MapPopulate/10 558ns ± 1% 556ns ± 1% ~ (p=0.157 n=10+10)
MapPopulate/100 7.75µs ± 1% 7.66µs ± 2% -1.19% (p=0.001 n=10+10)
MapPopulate/1000 92.6µs ± 1% 92.0µs ± 1% -0.61% (p=0.016 n=10+8)
MapPopulate/10000 817µs ± 1% 814µs ± 1% ~ (p=0.247 n=10+10)
MapPopulate/100000 8.02ms ± 1% 7.90ms ± 2% -1.47% (p=0.007 n=10+10)
Change-Id: If0eca9931379cbbd37eb753e9bcd2888d8272153
Reviewed-on: https://go-review.googlesource.com/62050
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/hashmap_fast.go | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/src/runtime/hashmap_fast.go b/src/runtime/hashmap_fast.go index 21e1f68bf7..e7b8448203 100644 --- a/src/runtime/hashmap_fast.go +++ b/src/runtime/hashmap_fast.go @@ -373,15 +373,14 @@ again: growWork_fast32(t, h, bucket) } b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + bucket*uintptr(t.bucketsize))) - top := tophash(hash) var inserti *uint8 var insertk unsafe.Pointer var val unsafe.Pointer for { for i := uintptr(0); i < bucketCnt; i++ { - if b.tophash[i] != top { - if b.tophash[i] == empty && inserti == nil { + if b.tophash[i] == empty { + if inserti == nil { inserti = &b.tophash[i] insertk = add(unsafe.Pointer(b), dataOffset+i*4) val = add(unsafe.Pointer(b), dataOffset+bucketCnt*4+i*uintptr(t.valuesize)) @@ -425,7 +424,8 @@ again: } else { *(*uint32)(insertk) = key } - *inserti = top + + *inserti = tophash(hash) h.count++ done: @@ -462,15 +462,14 @@ again: growWork_fast64(t, h, bucket) } b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + bucket*uintptr(t.bucketsize))) - top := tophash(hash) var inserti *uint8 var insertk unsafe.Pointer var val unsafe.Pointer for { for i := uintptr(0); i < bucketCnt; i++ { - if b.tophash[i] != top { - if b.tophash[i] == empty && inserti == nil { + if b.tophash[i] == empty { + if inserti == nil { inserti = &b.tophash[i] insertk = add(unsafe.Pointer(b), dataOffset+i*8) val = add(unsafe.Pointer(b), dataOffset+bucketCnt*8+i*uintptr(t.valuesize)) @@ -521,7 +520,7 @@ again: *(*uint64)(insertk) = key } - *inserti = top + *inserti = tophash(hash) h.count++ done: |