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Bug 1865865 - Add fast-path when computing segment's length is 1. r=TYLin

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When running wikipedia's page by browsertime benchmark, 0.5%-1% calls of
`LineBreaker::ComputeBreakPositions` is that aLength is 1. If this is 1,
we only set SOT break in ICU4X's line segmenter.

So we can add a fast-path for this situation. `ICU4XLineBreakIterator*`
always allocate rust heap, so we can reduce a few heap allocation costs.

Differential Revision: https://phabricator.services.mozilla.com/D195523
This commit is contained in:
Makoto Kato 2023-12-07 14:52:46 +00:00
parent 883a3c8e0b
commit 9f41fa963a
1 changed files with 18 additions and 0 deletions
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18
intl/lwbrk/LineBreaker.cpp
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@ -1093,6 +1093,15 @@ void LineBreaker::ComputeBreakPositions(
LineBreakRule aLevel, bool aIsChineseOrJapanese, uint8_t* aBreakBefore) {
#if defined(MOZ_ICU4X) && defined(JS_HAS_INTL_API)
if (StaticPrefs::intl_icu4x_segmenter_enabled()) {
if (aLength == 1) {
// Although UAX#14 LB2 rule requires never breaking at the start of text
// (SOT), ICU4X line segmenter API is designed to match other segmenter in
// UAX#29 to always break at the start of text. Hence the optimization
// here to avoid calling into ICU4X line segmenter.
aBreakBefore[0] = 1;
return;
}
memset(aBreakBefore, 0, aLength);
CheckedInt<int32_t> length = aLength;
@ -1253,6 +1262,15 @@ void LineBreaker::ComputeBreakPositions(const uint8_t* aChars, uint32_t aLength,
uint8_t* aBreakBefore) {
#if defined(MOZ_ICU4X) && defined(JS_HAS_INTL_API)
if (StaticPrefs::intl_icu4x_segmenter_enabled()) {
if (aLength == 1) {
// Although UAX#14 LB2 rule requires never breaking at the start of text
// (SOT), ICU4X line segmenter API is designed to match other segmenter in
// UAX#29 to always break at the start of text. Hence the optimization
// here to avoid calling into ICU4X line segmenter.
aBreakBefore[0] = 1;
return;
}
memset(aBreakBefore, 0, aLength);
CheckedInt<int32_t> length = aLength;