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bytes: speed up Replace 

This CL is to package bytes what CL 657935 was to package strings.

The length of parameter old does not change. Move the corresponding length
check outside the loop. Use range-over-int loops where possible.

Some benchmark results (no changes to allocations):

goos: darwin
goarch: amd64
pkg: bytes
cpu: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
                                 │     old      │                 new                 │
                                 │    sec/op    │   sec/op     vs base                │
Replace/"hello"_"l"_"L"_0-8         27.83n ± 2%   27.22n ± 1%   -2.17% (p=0.000 n=20)
Replace/"hello"_"l"_"L"_-1-8        60.64n ± 0%   57.97n ± 1%   -4.40% (p=0.000 n=20)
Replace/"hello"_"x"_"X"_-1-8        33.99n ± 0%   33.88n ± 0%        ~ (p=0.140 n=20)
Replace/""_"x"_"X"_-1-8             10.40n ± 1%   10.57n ± 0%   +1.64% (p=0.000 n=20)
Replace/"radar"_"r"_"<r>"_-1-8      62.63n ± 0%   61.39n ± 0%   -1.98% (p=0.000 n=20)
Replace/""_""_"<>"_-1-8             29.76n ± 1%   24.18n ± 1%  -18.75% (p=0.000 n=20)
Replace/"banana"_"a"_"<>"_-1-8      77.00n ± 0%   77.10n ± 1%        ~ (p=0.525 n=20)
Replace/"banana"_"a"_"<>"_1-8       44.24n ± 0%   43.57n ± 1%   -1.54% (p=0.000 n=20)
Replace/"banana"_"a"_"<>"_1000-8    78.23n ± 0%   77.16n ± 1%   -1.36% (p=0.000 n=20)
Replace/"banana"_"an"_"<>"_-1-8     72.78n ± 1%   69.97n ± 1%   -3.85% (p=0.000 n=20)
Replace/"banana"_"ana"_"<>"_-1-8    54.41n ± 0%   54.04n ± 1%   -0.67% (p=0.033 n=20)
Replace/"banana"_""_"<>"_-1-8       116.8n ± 1%   103.5n ± 1%  -11.42% (p=0.000 n=20)
Replace/"banana"_""_"<>"_10-8       117.2n ± 1%   103.6n ± 0%  -11.60% (p=0.000 n=20)
Replace/"banana"_""_"<>"_6-8       105.30n ± 0%   92.50n ± 0%  -12.16% (p=0.000 n=20)
Replace/"banana"_""_"<>"_5-8        91.81n ± 0%   79.87n ± 1%  -13.01% (p=0.000 n=20)
Replace/"banana"_""_"<>"_1-8        35.87n ± 1%   30.33n ± 1%  -15.43% (p=0.000 n=20)
Replace/"banana"_"a"_"a"_-1-8       70.84n ± 0%   68.83n ± 0%   -2.84% (p=0.000 n=20)
Replace/"banana"_"a"_"a"_1-8        44.27n ± 1%   43.47n ± 1%   -1.80% (p=0.000 n=20)
Replace/"☺☻☹"_""_"<>"_-1-8         104.25n ± 1%   93.33n ± 0%  -10.48% (p=0.000 n=20)
geomean                             56.31n        52.88n        -6.09%
This commit is contained in:
Julien Cretel 2025-03-20 12:35:11 +01:00
parent 6d2edacaf8
commit d1caf1f084
No known key found for this signature in database
GPG Key ID: 9BC102DCCA7031A9
1 changed files with 14 additions and 11 deletions
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25
src/bytes/bytes.go
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@ -1192,19 +1192,22 @@ func Replace(s, old, new []byte, n int) []byte {
t := make([]byte, len(s)+n*(len(new)-len(old)))
w := 0
start := 0
for i := 0; i < n; i++ {
j := start
if len(old) == 0 {
if i > 0 {
_, wid := utf8.DecodeRune(s[start:])
j += wid
}
} else {
j += Index(s[start:], old)
if len(old) > 0 {
for range n {
j := start + Index(s[start:], old)
w += copy(t[w:], s[start:j])
w += copy(t[w:], new)
start = j + len(old)
}
w += copy(t[w:], s[start:j])
} else { // len(old) == 0
w += copy(t[w:], new)
start = j + len(old)
for range n - 1 {
_, wid := utf8.DecodeRune(s[start:])
j := start + wid
w += copy(t[w:], s[start:j])
w += copy(t[w:], new)
start = j
}
}
w += copy(t[w:], s[start:])
return t[0:w]