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| author | Ilya Tocar <ilya.tocar@intel.com> | 2017-05-01 14:27:36 -0500 |
|---|---|---|
| committer | Brad Fitzpatrick <bradfitz@golang.org> | 2017-06-05 16:32:02 +0000 |
| commit | a4ee95c805fb77e594603bcd62d7858dc9e853ab (patch) | |
| tree | 8493667d75f0fbfab1b12d6b1821a9c2d668eda0 /src/runtime/mbitmap.go | |
| parent | d263e855977d49719ceea4da3b843bab5951dffb (diff) | |
| download | go-a4ee95c805fb77e594603bcd62d7858dc9e853ab.tar.gz go-a4ee95c805fb77e594603bcd62d7858dc9e853ab.zip | |
runtime: avoid division in gc
Replace int division with (cheaper) byte division in heapBitsSetType.
Provides noticeable speed-up:
GrowSlicePtr-6 181ns ± 3% 169ns ± 3% -6.85% (p=0.000 n=10+10)
Change-Id: I4064bb72e8e692023783b8f58d19491844c39382
Reviewed-on: https://go-review.googlesource.com/42290
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Diffstat (limited to 'src/runtime/mbitmap.go')
| -rw-r--r-- | src/runtime/mbitmap.go | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go index 82bfe84267..2a9f1b83e5 100644 --- a/src/runtime/mbitmap.go +++ b/src/runtime/mbitmap.go @@ -1047,7 +1047,9 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) { endnb += endnb } // Truncate to a multiple of original ptrmask. - endnb = maxBits / nb * nb + // Because nb+nb <= maxBits, nb fits in a byte. + // Byte division is cheaper than uintptr division. + endnb = uintptr(maxBits/byte(nb)) * nb pbits &= 1<<endnb - 1 b = pbits nb = endnb |