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alex/bench_test.go

Created August 29, 2019 20:20
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  1. alex created this gist Aug 29, 2019.
    83 changes: 83 additions & 0 deletions bench_test.go
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,83 @@
    package foo

    import (
    "bytes"
    "testing"
    )

    var Data1 = bytes.Repeat([]byte("a"), 1)
    var Data10 = bytes.Repeat([]byte("a"), 10)
    var Data100 = bytes.Repeat([]byte("a"), 100)
    var Data1000 = bytes.Repeat([]byte("a"), 1000)
    var Data10000 = bytes.Repeat([]byte("a"), 10000)


    func BenchmarkLinear_1(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    linearFindFirstMultiByteChar(Data1)
    }
    }

    func BenchmarkVectorize_1(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    vectorizeFindFirstMultiByteChar(Data1)
    }
    }

    func BenchmarkLinear_10(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    linearFindFirstMultiByteChar(Data10)
    }
    }

    func BenchmarkVectorize_10(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    vectorizeFindFirstMultiByteChar(Data10)
    }
    }

    func BenchmarkLinear_100(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    linearFindFirstMultiByteChar(Data100)
    }
    }

    func BenchmarkVectorize_100(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    vectorizeFindFirstMultiByteChar(Data100)
    }
    }

    func BenchmarkLinear_1000(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    linearFindFirstMultiByteChar(Data1000)
    }
    }

    func BenchmarkVectorize_1000(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    vectorizeFindFirstMultiByteChar(Data1000)
    }
    }

    func BenchmarkLinear_10000(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    linearFindFirstMultiByteChar(Data10000)
    }
    }

    func BenchmarkVectorize_10000(b *testing.B) {
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
    vectorizeFindFirstMultiByteChar(Data10000)
    }
    }
    15 changes: 15 additions & 0 deletions results.txt
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    @@ -0,0 +1,15 @@
    alex@penguin /t/yy> go test -bench=.
    goos: linux
    goarch: amd64
    pkg: foo
    BenchmarkLinear_1-4 500000000 3.53 ns/op
    BenchmarkVectorize_1-4 300000000 4.33 ns/op
    BenchmarkLinear_10-4 200000000 9.82 ns/op
    BenchmarkVectorize_10-4 200000000 6.70 ns/op
    BenchmarkLinear_100-4 20000000 77.2 ns/op
    BenchmarkVectorize_100-4 100000000 14.2 ns/op
    BenchmarkLinear_1000-4 2000000 690 ns/op
    BenchmarkVectorize_1000-4 20000000 98.7 ns/op
    BenchmarkLinear_10000-4 200000 7754 ns/op
    BenchmarkVectorize_10000-4 2000000 891 ns/op
    PASS
    42 changes: 42 additions & 0 deletions yy.go
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    Original file line number Diff line number Diff line change
    @@ -0,0 +1,42 @@
    package foo

    import (
    "unsafe"
    )

    func linearFindFirstMultiByteChar(bytes []byte) int {
    for bytesIdx, b := range bytes {
    // We have a multi-byte codepoint, we need to allocate
    // codepointIndices
    if b&0x80 == 0x80 {
    return bytesIdx
    }
    }
    return len(bytes)

    }

    const wordSize = int(unsafe.Sizeof(uintptr(0)))

    func vectorizeFindFirstMultiByteChar(bytes []byte) int {
    // TODO: check if unaligned is allowed
    // Attempt to do a vectorized scan.
    if len(bytes) > wordSize {
    w := len(bytes) / wordSize
    bytesw := *(*[]uintptr)(unsafe.Pointer(&bytes))
    for i := 0; i < w; i++ {
    if bytesw[i]&uintptr(0x8080808080808080) != 0 {
    return i * wordSize
    }
    }
    }

    for i := len(bytes) - (len(bytes) % wordSize); i < len(bytes); i++ {
    if bytes[i]&0x80 == 0x80 {
    return i
    }
    }

    return len(bytes)

    }