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style: Avoid some branches in common RuleIterator::next cases.

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I saw this function appear in the profiles at #17329.

It was under set_device, which isn't a Stylo path, but probably worth there
anyway.

This reduces the reported overhead of RulesIterator::next in perf from ~8% to
0.46%
This commit is contained in:
Emilio Cobos Álvarez 2017-06-15 03:14:08 +02:00
parent b741df3525
commit b41f741f5b
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GPG key ID: 056B727BB9C1027C
1 changed files with 18 additions and 20 deletions
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38
components/style/stylesheets/rules_iterator.rs
View file

@ -68,8 +68,7 @@ impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
}
let rule;
let sub_iter;
{
let sub_iter = {
let mut nested_iter = self.stack.last_mut().unwrap();
rule = match nested_iter.next() {
Some(r) => r,
@ -79,7 +78,16 @@ impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
}
};
sub_iter = match *rule {
match *rule {
CssRule::Namespace(_) |
CssRule::Style(_) |
CssRule::FontFace(_) |
CssRule::CounterStyle(_) |
CssRule::Viewport(_) |
CssRule::Keyframes(_) |
CssRule::Page(_) => {
return Some(rule)
},
CssRule::Import(ref import_rule) => {
let import_rule = import_rule.read_with(self.guard);
if !C::process_import(self.guard,
@ -88,7 +96,7 @@ impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
import_rule) {
continue;
}
Some(import_rule.stylesheet.rules.read_with(self.guard).0.iter())
import_rule.stylesheet.rules.read_with(self.guard).0.iter()
}
CssRule::Document(ref doc_rule) => {
let doc_rule = doc_rule.read_with(self.guard);
@ -98,7 +106,7 @@ impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
doc_rule) {
continue;
}
Some(doc_rule.rules.read_with(self.guard).0.iter())
doc_rule.rules.read_with(self.guard).0.iter()
}
CssRule::Media(ref lock) => {
let media_rule = lock.read_with(self.guard);
@ -108,7 +116,7 @@ impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
media_rule) {
continue;
}
Some(media_rule.rules.read_with(self.guard).0.iter())
media_rule.rules.read_with(self.guard).0.iter()
}
CssRule::Supports(ref lock) => {
let supports_rule = lock.read_with(self.guard);
@ -118,22 +126,12 @@ impl<'a, 'b, C> Iterator for RulesIterator<'a, 'b, C>
supports_rule) {
continue;
}
Some(supports_rule.rules.read_with(self.guard).0.iter())
supports_rule.rules.read_with(self.guard).0.iter()
}
CssRule::Namespace(_) |
CssRule::Style(_) |
CssRule::FontFace(_) |
CssRule::CounterStyle(_) |
CssRule::Viewport(_) |
CssRule::Keyframes(_) |
CssRule::Page(_) => None,
};
}
if let Some(sub_iter) = sub_iter {
self.stack.push(sub_iter);
}
}
};
self.stack.push(sub_iter);
return Some(rule);
}