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Use a different visitor pass for gathering revalidation selectors.

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This allows us to ignore everything to the left of the rightmost simple selector.

MozReview-Commit-ID: 6I4VzKos22n
This commit is contained in:
Bobby Holley 2017-04-24 13:06:44 -07:00
parent dd4575c23a
commit 2df9dc2b03
2 changed files with 77 additions and 51 deletions
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49
components/style/restyle_hints.rs
View file

@ -417,38 +417,6 @@ fn is_attr_selector(sel: &Component<SelectorImpl>) -> bool {
}
}
/// Whether a selector containing this simple selector needs to be explicitly
/// matched against both the style sharing cache entry and the candidate.
///
/// We use this for selectors that can have different matching behavior between
/// siblings that are otherwise identical as far as the cache is concerned.
fn needs_cache_revalidation(sel: &Component<SelectorImpl>) -> bool {
match *sel {
Component::AttrExists(_) |
Component::AttrEqual(_, _, _) |
Component::AttrIncludes(_, _) |
Component::AttrDashMatch(_, _) |
Component::AttrPrefixMatch(_, _) |
Component::AttrSubstringMatch(_, _) |
Component::AttrSuffixMatch(_, _) |
Component::Empty |
Component::FirstChild |
Component::LastChild |
Component::OnlyChild |
Component::NthChild(..) |
Component::NthLastChild(..) |
Component::NthOfType(..) |
Component::NthLastOfType(..) |
Component::FirstOfType |
Component::LastOfType |
Component::OnlyOfType => true,
// FIXME(emilio): This sets the "revalidation" flag for :any, which is
// probably expensive given we use it a lot in UA sheets.
Component::NonTSPseudoClass(ref p) => p.state_flag().is_empty(),
_ => false,
}
}
fn combinator_to_restyle_hint(combinator: Option<Combinator>) -> RestyleHint {
match combinator {
None => RESTYLE_SELF,
@ -515,7 +483,6 @@ struct Dependency {
struct SensitivitiesVisitor {
sensitivities: Sensitivities,
hint: RestyleHint,
needs_revalidation: bool,
}
impl SelectorVisitor for SensitivitiesVisitor {
@ -525,7 +492,6 @@ impl SelectorVisitor for SensitivitiesVisitor {
_: SelectorIter<SelectorImpl>,
combinator: Option<Combinator>) -> bool {
self.hint |= combinator_to_restyle_hint(combinator);
self.needs_revalidation |= self.hint.contains(RESTYLE_LATER_SIBLINGS);
true
}
@ -537,10 +503,6 @@ impl SelectorVisitor for SensitivitiesVisitor {
self.sensitivities.attrs = is_attr_selector(s);
}
if !self.needs_revalidation {
self.needs_revalidation = needs_cache_revalidation(s);
}
true
}
}
@ -575,22 +537,18 @@ impl DependencySet {
}
}
/// Adds a selector to this `DependencySet`, and returns whether it may need
/// cache revalidation, that is, whether two siblings of the same "shape"
/// may have different style due to this selector.
pub fn note_selector(&mut self, selector: &Selector<SelectorImpl>) -> bool {
/// Adds a selector to this `DependencySet`.
pub fn note_selector(&mut self, selector: &Selector<SelectorImpl>) {
let mut is_pseudo_element = selector.pseudo_element.is_some();
let mut next = Some(selector.inner.complex.clone());
let mut combinator = None;
let mut needs_revalidation = false;
while let Some(current) = next.take() {
// Set up our visitor.
let mut visitor = SensitivitiesVisitor {
sensitivities: Sensitivities::new(),
hint: combinator_to_restyle_hint(combinator),
needs_revalidation: false,
};
if is_pseudo_element {
@ -623,7 +581,6 @@ impl DependencySet {
}
// Note what we found.
needs_revalidation |= visitor.needs_revalidation;
if !visitor.sensitivities.is_empty() {
self.add_dependency(Dependency {
sensitivities: visitor.sensitivities,
@ -633,8 +590,6 @@ impl DependencySet {
}
}
needs_revalidation
}
/// Create an empty `DependencySet`.

79
components/style/stylist.rs
View file

@ -26,7 +26,8 @@ use selectors::Element;
use selectors::bloom::BloomFilter;
use selectors::matching::{AFFECTED_BY_STYLE_ATTRIBUTE, AFFECTED_BY_PRESENTATIONAL_HINTS};
use selectors::matching::{ElementSelectorFlags, StyleRelations, matches_selector};
use selectors::parser::{Component, Selector, SelectorInner, LocalName as LocalNameSelector};
use selectors::parser::{Component, Selector, SelectorInner, SelectorMethods, LocalName as LocalNameSelector};
use selectors::visitor::SelectorVisitor;
use shared_lock::{Locked, SharedRwLockReadGuard, StylesheetGuards};
use sink::Push;
use smallvec::VecLike;
@ -332,9 +333,9 @@ impl Stylist {
self.rules_source_order += 1;
for selector in &style_rule.selectors.0 {
let needs_cache_revalidation =
self.dependencies.note_selector(selector);
if needs_cache_revalidation {
self.dependencies.note_selector(selector);
if needs_revalidation(selector) {
self.selectors_for_cache_revalidation.push(selector.clone());
}
}
@ -902,6 +903,76 @@ impl Drop for Stylist {
}
}
/// Visitor determine whether a selector requires cache revalidation.
///
/// Note that we just check simple selectors and eagerly return when the first
/// need for revalidation is found, so we don't need to store state on the visitor.
struct RevalidationVisitor;
impl SelectorVisitor for RevalidationVisitor {
type Impl = SelectorImpl;
/// Check whether a rightmost sequence of simple selectors containing this
/// simple selector to be explicitly matched against both the style sharing
/// cache entry and the candidate.
///
/// We use this for selectors that can have different matching behavior between
/// siblings that are otherwise identical as far as the cache is concerned.
fn visit_simple_selector(&mut self, s: &Component<SelectorImpl>) -> bool {
match *s {
Component::AttrExists(_) |
Component::AttrEqual(_, _, _) |
Component::AttrIncludes(_, _) |
Component::AttrDashMatch(_, _) |
Component::AttrPrefixMatch(_, _) |
Component::AttrSubstringMatch(_, _) |
Component::AttrSuffixMatch(_, _) |
Component::Empty |
Component::FirstChild |
Component::LastChild |
Component::OnlyChild |
Component::NthChild(..) |
Component::NthLastChild(..) |
Component::NthOfType(..) |
Component::NthLastOfType(..) |
Component::FirstOfType |
Component::LastOfType |
Component::OnlyOfType => {
false
},
// FIXME(emilio): This sets the "revalidation" flag for :any, which is
// probably expensive given we use it a lot in UA sheets.
Component::NonTSPseudoClass(ref p) if p.state_flag().is_empty() => {
false
},
_ => {
true
}
}
}
}
/// Returns true if the given selector needs cache revalidation.
pub fn needs_revalidation(selector: &Selector<SelectorImpl>) -> bool {
let mut visitor = RevalidationVisitor;
// We only need to consider the rightmost sequence of simple selectors, so
// we can stop at the first combinator. This is because:
// * If it's an ancestor combinator, we can ignore everything to the left
// because matching won't differ between siblings.
// * If it's a sibling combinator, then we know we need revalidation.
let mut iter = selector.inner.complex.iter();
for ss in &mut iter {
if !ss.visit(&mut visitor) {
return true;
}
}
// If none of the simple selectors in the rightmost sequence required
// revalidaiton, we need revalidation if and only if the combinator is
// a sibling combinator.
iter.next_sequence().map_or(false, |c| c.is_sibling())
}
/// Map that contains the CSS rules for a specific PseudoElement
/// (or lack of PseudoElement).