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unicode/utf8: speedup RuneCount

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CL 612617 did speedup RuneCountInString, thus we can now use it to
speedup RuneCount, too.

name                         old time/op    new time/op    delta
RuneCountTenASCIIChars-8       8.69ns ± 1%    3.59ns ± 2%  -58.66%  (p=0.000 n=9+9)
RuneCountTenJapaneseChars-8    49.8ns ± 2%    40.9ns ± 0%  -17.94%  (p=0.000 n=10+8)

Change-Id: I311750c00efc79af35fb0ca3b482a5d94e0a7977
Reviewed-on: https://go-review.googlesource.com/c/go/+/612955
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Tim King <taking@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Cuong Manh Le 2024-09-13 10:15:51 +07:00 committed by Gopher Robot
parent 9bd34ebb7e
commit 3d33437c45
1 changed files with 4 additions and 28 deletions
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32
src/unicode/utf8/utf8.go
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@ -414,35 +414,11 @@ func appendRuneNonASCII(p []byte, r rune) []byte {
func RuneCount(p []byte) int {
np := len(p)
var n int
for i := 0; i < np; {
n++
c := p[i]
if c < RuneSelf {
// ASCII fast path
i++
continue
for ; n < np; n++ {
if c := p[n]; c >= RuneSelf {
// non-ASCII slow path
return n + RuneCountInString(string(p[n:]))
}
x := first[c]
if x == xx {
i++ // invalid.
continue
}
size := int(x & 7)
if i+size > np {
i++ // Short or invalid.
continue
}
accept := acceptRanges[x>>4]
if c := p[i+1]; c < accept.lo || accept.hi < c {
size = 1
} else if size == 2 {
} else if c := p[i+2]; c < locb || hicb < c {
size = 1
} else if size == 3 {
} else if c := p[i+3]; c < locb || hicb < c {
size = 1
}
i += size
}
return n
}