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Auto merge of #18798 - emilio:faster-custom-props, r=SimonSapin

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style: Optimize custom properties cycle removal.

After #18791, this is the major custom_properties perf bottleneck in the
testcase from bug 1405411.

I'm looking into how to efficiently merge this into `substitute_all`, but
meanwhile this is worth landing, and makes most of the overhead go away.

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This commit is contained in:
bors-servo 2017-10-10 02:47:29 -05:00 • committed by GitHub
commit 27cb13314e
1 changed files with 25 additions and 17 deletions
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42
components/style/custom_properties.rs
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@ -13,6 +13,7 @@ use properties::{CSSWideKeyword, DeclaredValue};
use selector_map::{PrecomputedHashSet, PrecomputedHashMap, PrecomputedDiagnosticHashMap}; use selector_map::{PrecomputedHashSet, PrecomputedHashMap, PrecomputedDiagnosticHashMap};
use selectors::parser::SelectorParseError; use selectors::parser::SelectorParseError;
use servo_arc::Arc; use servo_arc::Arc;
use smallvec::SmallVec;
use std::ascii::AsciiExt; use std::ascii::AsciiExt;
use std::borrow::{Borrow, Cow}; use std::borrow::{Borrow, Cow};
use std::fmt; use std::fmt;
@ -546,41 +547,48 @@ impl<'a> CustomPropertiesBuilder<'a> {
fn remove_cycles(map: &mut CustomPropertiesMap) { fn remove_cycles(map: &mut CustomPropertiesMap) {
let mut to_remove = PrecomputedHashSet::default(); let mut to_remove = PrecomputedHashSet::default();
{ {
type VisitedNamesStack<'a> = SmallVec<[&'a Name; 10]>;
let mut visited = PrecomputedHashSet::default(); let mut visited = PrecomputedHashSet::default();
let mut stack = Vec::new(); let mut stack = VisitedNamesStack::new();
for name in &map.index { for (name, value) in map.iter() {
walk(map, name, &mut stack, &mut visited, &mut to_remove); walk(map, name, value, &mut stack, &mut visited, &mut to_remove);
fn walk<'a>( fn walk<'a>(
map: &'a CustomPropertiesMap, map: &'a CustomPropertiesMap,
name: &'a Name, name: &'a Name,
stack: &mut Vec<&'a Name>, value: &'a Arc<VariableValue>,
stack: &mut VisitedNamesStack<'a>,
visited: &mut PrecomputedHashSet<&'a Name>, visited: &mut PrecomputedHashSet<&'a Name>,
to_remove: &mut PrecomputedHashSet<Name>, to_remove: &mut PrecomputedHashSet<Name>,
) { ) {
if value.references.is_empty() {
return;
}
let already_visited_before = !visited.insert(name); let already_visited_before = !visited.insert(name);
if already_visited_before { if already_visited_before {
return return
} }
if let Some(ref value) = map.get(name) {
if !value.references.is_empty() { stack.push(name);
stack.push(name); for next in value.references.iter() {
for next in value.references.iter() { if let Some(position) = stack.iter().position(|x| *x == next) {
if let Some(position) = stack.iter().position(|x| *x == next) { // Found a cycle
// Found a cycle for &in_cycle in &stack[position..] {
for &in_cycle in &stack[position..] { to_remove.insert(in_cycle.clone());
to_remove.insert(in_cycle.clone()); }
} } else {
} else { if let Some(value) = map.get(next) {
walk(map, next, stack, visited, to_remove); walk(map, next, value, stack, visited, to_remove);
}
} }
stack.pop();
} }
} }
stack.pop();
} }
} }
} }
for name in to_remove { for name in to_remove {
map.remove(&name); map.remove(&name);
} }