From 97dfbc54e675b7ec94bfdb3bed453ffa938b77d5 Mon Sep 17 00:00:00 2001 From: Josh Bleecher Snyder Date: Tue, 23 Apr 2019 13:30:03 -0700 Subject: [PATCH] unicode/utf8: make acceptRanges bigger MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This avoids bounds checks in the calling code. The nominal increased size of the array in the binary is compensated for by the decreased size of the functions that call it. The benchmark changes are a bit scattered, but overall positive. name old time/op new time/op delta RuneCountTenASCIIChars-8 8.86ns ± 4% 7.93ns ± 5% -10.45% (p=0.000 n=45+49) RuneCountTenJapaneseChars-8 38.2ns ± 2% 37.2ns ± 1% -2.63% (p=0.000 n=44+41) RuneCountInStringTenASCIIChars-8 7.82ns ± 2% 8.70ns ± 2% +11.19% (p=0.000 n=43+43) RuneCountInStringTenJapaneseChars-8 39.3ns ± 9% 40.0ns ± 5% +1.59% (p=0.043 n=50+50) ValidTenASCIIChars-8 8.68ns ± 5% 8.74ns ± 5% ~ (p=0.070 n=50+48) ValidTenJapaneseChars-8 34.1ns ± 5% 36.8ns ± 4% +8.09% (p=0.000 n=45+50) ValidStringTenASCIIChars-8 9.76ns ± 7% 8.33ns ± 3% -14.59% (p=0.000 n=48+47) ValidStringTenJapaneseChars-8 37.7ns ± 8% 36.5ns ± 5% -3.12% (p=0.011 n=50+47) EncodeASCIIRune-8 2.60ns ± 1% 2.59ns ± 2% -0.24% (p=0.018 n=43+36) EncodeJapaneseRune-8 3.75ns ± 2% 4.56ns ± 6% +21.71% (p=0.000 n=41+50) DecodeASCIIRune-8 2.59ns ± 2% 2.59ns ± 2% ~ (p=0.350 n=44+41) DecodeJapaneseRune-8 4.29ns ± 2% 4.31ns ± 2% +0.61% (p=0.001 n=48+39) FullASCIIRune-8 0.87ns ± 6% 0.29ns ± 5% -67.31% (p=0.000 n=49+43) FullJapaneseRune-8 0.65ns ± 6% 0.65ns ± 4% ~ (p=0.375 n=50+49) [Geo mean] 7.02ns 6.51ns -7.19% Change-Id: I8d5d69c8d33ce2bff94785fba39a2203f9315cb0 Reviewed-on: https://go-review.googlesource.com/c/go/+/173537 Run-TryBot: Josh Bleecher Snyder TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick --- src/unicode/utf8/utf8.go | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/unicode/utf8/utf8.go b/src/unicode/utf8/utf8.go index db845ab2f2..b351cc351f 100644 --- a/src/unicode/utf8/utf8.go +++ b/src/unicode/utf8/utf8.go @@ -89,7 +89,8 @@ type acceptRange struct { hi uint8 // highest value for second byte. } -var acceptRanges = [...]acceptRange{ +// acceptRanges has size 16 to avoid bounds checks in the code that uses it. +var acceptRanges = [16]acceptRange{ 0: {locb, hicb}, 1: {0xA0, hicb}, 2: {locb, 0x9F}, -- 2.48.1