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go/src/strings
Robert Griesemer e193725184 strings: simpler and slightly faster implementation of FieldsFunc
Removed the need for maintaining an extra variable in one of the inner loops,
leading to a slight speed-up for short strings.

Benchmarks run on a "quiet" MacBook Pro, 3.3GHz Dual-Core Intel Core i7,
with 16GB 2133MHz LPDDR3 RAM running macOS 10.15.4.

name                        old time/op    new time/op    delta
FieldsFunc/ASCII/16-4          147ns ± 0%     144ns ± 1%  -2.04%  (p=0.000 n=4+5)
FieldsFunc/ASCII/256-4        1.63µs ± 0%    1.59µs ± 1%  -2.50%  (p=0.008 n=5+5)
FieldsFunc/ASCII/4096-4       30.0µs ± 0%    29.3µs ± 2%    ~     (p=0.190 n=4+5)
FieldsFunc/ASCII/65536-4       491µs ± 5%     473µs ± 2%    ~     (p=0.095 n=5+5)
FieldsFunc/ASCII/1048576-4    8.02ms ± 7%    7.85ms ± 4%    ~     (p=0.548 n=5+5)
FieldsFunc/Mixed/16-4          182ns ± 1%     181ns ± 4%    ~     (p=0.357 n=5+5)
FieldsFunc/Mixed/256-4        1.74µs ± 1%    1.74µs ± 1%    ~     (p=0.881 n=5+5)
FieldsFunc/Mixed/4096-4       34.9µs ± 2%    34.7µs ± 0%    ~     (p=0.310 n=5+5)
FieldsFunc/Mixed/65536-4       595µs ± 1%     589µs ± 2%    ~     (p=0.095 n=5+5)
FieldsFunc/Mixed/1048576-4    10.1ms ± 3%     9.8ms ± 2%    ~     (p=0.095 n=5+5)

name                        old speed      new speed      delta
FieldsFunc/ASCII/16-4        109MB/s ± 1%   111MB/s ± 1%  +2.33%  (p=0.008 n=5+5)
FieldsFunc/ASCII/256-4       157MB/s ± 0%   161MB/s ± 1%  +2.57%  (p=0.008 n=5+5)
FieldsFunc/ASCII/4096-4      137MB/s ± 0%   140MB/s ± 2%    ~     (p=0.190 n=4+5)
FieldsFunc/ASCII/65536-4     134MB/s ± 4%   139MB/s ± 2%    ~     (p=0.095 n=5+5)
FieldsFunc/ASCII/1048576-4   131MB/s ± 6%   134MB/s ± 4%    ~     (p=0.548 n=5+5)
FieldsFunc/Mixed/16-4       87.8MB/s ± 1%  88.3MB/s ± 4%    ~     (p=0.421 n=5+5)
FieldsFunc/Mixed/256-4       147MB/s ± 1%   147MB/s ± 1%    ~     (p=0.841 n=5+5)
FieldsFunc/Mixed/4096-4      117MB/s ± 2%   118MB/s ± 0%    ~     (p=0.310 n=5+5)
FieldsFunc/Mixed/65536-4     110MB/s ± 1%   111MB/s ± 2%    ~     (p=0.095 n=5+5)
FieldsFunc/Mixed/1048576-4   104MB/s ± 3%   107MB/s ± 2%    ~     (p=0.095 n=5+5)

name                        old alloc/op   new alloc/op   delta
FieldsFunc/ASCII/16-4          32.0B ± 0%     32.0B ± 0%    ~     (all equal)
FieldsFunc/ASCII/256-4          352B ± 0%      352B ± 0%    ~     (all equal)
FieldsFunc/ASCII/4096-4       21.9kB ± 0%    21.9kB ± 0%    ~     (all equal)
FieldsFunc/ASCII/65536-4       448kB ± 0%     448kB ± 0%    ~     (all equal)
FieldsFunc/ASCII/1048576-4    8.85MB ± 0%    8.85MB ± 0%    ~     (p=0.738 n=5+5)
FieldsFunc/Mixed/16-4          48.0B ± 0%     48.0B ± 0%    ~     (all equal)
FieldsFunc/Mixed/256-4          416B ± 0%      416B ± 0%    ~     (all equal)
FieldsFunc/Mixed/4096-4       21.5kB ± 0%    21.5kB ± 0%    ~     (all equal)
FieldsFunc/Mixed/65536-4       448kB ± 0%     448kB ± 0%    ~     (all equal)
FieldsFunc/Mixed/1048576-4    8.85MB ± 0%    8.85MB ± 0%    ~     (p=0.690 n=5+5)

name                        old allocs/op  new allocs/op  delta
FieldsFunc/ASCII/16-4           1.00 ± 0%      1.00 ± 0%    ~     (all equal)
FieldsFunc/ASCII/256-4          1.00 ± 0%      1.00 ± 0%    ~     (all equal)
FieldsFunc/ASCII/4096-4         5.00 ± 0%      5.00 ± 0%    ~     (all equal)
FieldsFunc/ASCII/65536-4        12.0 ± 0%      12.0 ± 0%    ~     (all equal)
FieldsFunc/ASCII/1048576-4      24.0 ± 0%      24.0 ± 0%    ~     (all equal)
FieldsFunc/Mixed/16-4           1.00 ± 0%      1.00 ± 0%    ~     (all equal)
FieldsFunc/Mixed/256-4          1.00 ± 0%      1.00 ± 0%    ~     (all equal)
FieldsFunc/Mixed/4096-4         5.00 ± 0%      5.00 ± 0%    ~     (all equal)
FieldsFunc/Mixed/65536-4        12.0 ± 0%      12.0 ± 0%    ~     (all equal)
FieldsFunc/Mixed/1048576-4      24.0 ± 0%      24.0 ± 0%    ~     (all equal)

Change-Id: I06828d798ca1a624a26edd7f7b68c3bf2fc28f84
Reviewed-on: https://go-review.googlesource.com/c/go/+/229765
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
2020-04-28 20:18:12 +00:00
..
builder_test.go strings: remove a redundant and flaky part of a test 2019-10-31 20:45:40 +00:00
builder.go cmd/compile: add -d=checkptr to validate unsafe.Pointer rules 2019-10-17 00:40:21 +00:00
compare_test.go strings: lower running time of TestCompareStrings 2018-11-04 18:55:55 +00:00
compare.go
example_test.go strings: clarify usage of Title and ToTitle 2019-07-30 02:52:57 +00:00
export_test.go strings: select Replacer algorithm and build machine lazily 2018-08-21 02:50:58 +00:00
reader_test.go bytes, strings: fix Reader.UnreadRune returning without error on a zero Reader 2018-10-29 20:07:25 +00:00
reader.go bytes, strings: fix Reader.UnreadRune returning without error on a zero Reader 2018-10-29 20:07:25 +00:00
replace_test.go
replace.go strings: document that order of pairs matters in NewReplacer 2019-07-10 21:26:21 +00:00
search_test.go
search.go
strings_test.go strings, bytes: improve IndexAny and LastIndexAny performance 2020-03-11 05:13:13 +00:00
strings.go strings: simpler and slightly faster implementation of FieldsFunc 2020-04-28 20:18:12 +00:00