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Shrink ElementData by moving pseudo count to type

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`ElementStyles` holds an optional list of values for each eager pseudo-element.
However, the type was declared as a slice instead of a fixed size array, so an
extra 8 bytes were being allocated to hold the size, even though it never
changes.

Moving the constant size into the type reduces `ElementStyles` and `ElementData`
by 8 bytes.

MozReview-Commit-ID: GaO6DKFxUMo
This commit is contained in:
J. Ryan Stinnett 2017-06-20 14:02:45 -05:00
parent 2b5c56e6a8
commit 87c51bd8bf
2 changed files with 21 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

22
components/style/data.rs
View file

@ -100,8 +100,24 @@ impl RestyleData {
/// A list of styles for eagerly-cascaded pseudo-elements.
/// Lazily-allocated.
#[derive(Clone, Debug)]
pub struct EagerPseudoStyles(pub Option<Box<[Option<Arc<ComputedValues>>]>>);
#[derive(Debug)]
pub struct EagerPseudoStyles(pub Option<Box<[Option<Arc<ComputedValues>>; EAGER_PSEUDO_COUNT]>>);
// Manually implement `Clone` here because the derived impl of `Clone` for
// array types assumes the value inside is `Copy`.
impl Clone for EagerPseudoStyles {
fn clone(&self) -> Self {
if self.0.is_none() {
return EagerPseudoStyles(None)
}
let self_values = self.0.as_ref().unwrap();
let mut values: [Option<Arc<ComputedValues>>; EAGER_PSEUDO_COUNT] = Default::default();
for i in 0..EAGER_PSEUDO_COUNT {
values[i] = self_values[i].clone();
}
EagerPseudoStyles(Some(Box::new(values)))
}
}
impl EagerPseudoStyles {
/// Returns whether there are any pseudo styles.
@ -129,7 +145,7 @@ impl EagerPseudoStyles {
/// Sets the style for the eager pseudo.
pub fn set(&mut self, pseudo: &PseudoElement, value: Arc<ComputedValues>) {
if self.0.is_none() {
self.0 = Some(vec![None; EAGER_PSEUDO_COUNT].into_boxed_slice());
self.0 = Some(Box::new(Default::default()));
}
self.0.as_mut().unwrap()[pseudo.eager_index()] = Some(value);
}

4
tests/unit/stylo/size_of.rs
View file

@ -32,9 +32,9 @@ size_of_test!(test_size_of_rule, style::stylist::Rule, 32);
size_of_test!(test_size_of_option_arc_cv, Option<Arc<ComputedValues>>, 8);
size_of_test!(test_size_of_option_rule_node, Option<StrongRuleNode>, 8);
size_of_test!(test_size_of_element_styles, ElementStyles, 24);
size_of_test!(test_size_of_element_styles, ElementStyles, 16);
size_of_test!(test_size_of_restyle_data, RestyleData, 8);
size_of_test!(test_size_of_element_data, ElementData, 32);
size_of_test!(test_size_of_element_data, ElementData, 24);
size_of_test!(test_size_of_property_declaration, style::properties::PropertyDeclaration, 32);