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style: Optimize cascading of other wide keywords if possible.

The way the copy-on-write stuff works, and the way that we have to apply
properties from most specific to less specific guarantees that always that we're
going to inherit an inherited property, or reset a reset property, we have
already the right value on the style.

Revert relies on that, so there doesn't seem to be a reason to not use that fact
more often and skip useless work earlier.

Font-size is still special of course... I think I have a way to move the
specialness outside of the style, but piece by piece.

Differential Revision: https://phabricator.services.mozilla.com/D21882
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emilio committed Mar 7, 2019
1 parent 6fd17cc commit 4a1f390788f647c4a96371a8a6608a677b600552
@@ -11,7 +11,7 @@ use crate::font_metrics::FontMetricsProvider;
use crate::logical_geometry::WritingMode;
use crate::media_queries::Device;
use crate::properties::{ComputedValues, StyleBuilder};
use crate::properties::{LonghandId, LonghandIdSet};
use crate::properties::{LonghandId, LonghandIdSet, CSSWideKeyword};
use crate::properties::{PropertyDeclaration, PropertyDeclarationId, DeclarationImportanceIterator};
use crate::properties::CASCADE_PROPERTY;
use crate::rule_cache::{RuleCache, RuleCacheConditions};
@@ -542,7 +542,11 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {
}
}

if declaration.is_revert() {
let css_wide_keyword = declaration.get_css_wide_keyword();
if let Some(CSSWideKeyword::Revert) = css_wide_keyword {
// We intentionally don't want to insert it into `self.seen`,
// `reverted` takes care of rejecting other declarations as
// needed.
for origin in origin.following_including() {
self.reverted
.borrow_mut_for_origin(&origin)
@@ -553,6 +557,19 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {

self.seen.insert(physical_longhand_id);

let unset = css_wide_keyword.map_or(false, |css_wide_keyword| {
match css_wide_keyword {
CSSWideKeyword::Unset => true,
CSSWideKeyword::Inherit => inherited,
CSSWideKeyword::Initial => !inherited,
CSSWideKeyword::Revert => unreachable!(),
}
});

if unset {
continue;
}

// FIXME(emilio): We should avoid generating code for logical
// longhands and just use the physical ones, then rename
// physical_longhand_id to just longhand_id.
@@ -811,18 +828,14 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {
self.seen.contains(LonghandId::MozMinFontSizeRatio) ||
self.seen.contains(LonghandId::FontFamily)
{
use crate::properties::{CSSWideKeyword, WideKeywordDeclaration};
use crate::values::computed::FontSize;

// font-size must be explicitly inherited to handle lang
// changes and scriptlevel changes.
//
// FIXME(emilio): That looks a bit bogus...
let inherit = PropertyDeclaration::CSSWideKeyword(WideKeywordDeclaration {
id: LonghandId::FontSize,
keyword: CSSWideKeyword::Inherit,
});

self.apply_declaration_ignoring_phase(LonghandId::FontSize, &inherit);
self.context.for_non_inherited_property = None;
FontSize::cascade_inherit_font_size(&mut self.context);
}
}
}
@@ -326,26 +326,28 @@
PropertyDeclaration::CSSWideKeyword(ref declaration) => {
debug_assert_eq!(declaration.id, LonghandId::${property.camel_case});
match declaration.keyword {
% if not data.current_style_struct.inherited:
% if not property.style_struct.inherited:
CSSWideKeyword::Unset |
% endif
CSSWideKeyword::Initial => {
% if property.ident == "font_size":
computed::FontSize::cascade_initial_font_size(context);
% if not property.style_struct.inherited:
debug_assert!(false, "Should be handled in apply_properties");
% else:
% if property.name == "font-size":
computed::FontSize::cascade_initial_font_size(context);
% else:
context.builder.reset_${property.ident}();
% endif
% endif
},
% if data.current_style_struct.inherited:
% if property.style_struct.inherited:
CSSWideKeyword::Unset |
% endif
CSSWideKeyword::Inherit => {
% if not property.style_struct.inherited:
context.rule_cache_conditions.borrow_mut().set_uncacheable();
% endif
% if property.ident == "font_size":
computed::FontSize::cascade_inherit_font_size(context);
% if property.style_struct.inherited:
debug_assert!(false, "Should be handled in apply_properties");
% else:
context.rule_cache_conditions.borrow_mut().set_uncacheable();
context.builder.inherit_${property.ident}();
% endif
}
@@ -2117,12 +2117,6 @@ impl PropertyDeclaration {
}
}

/// Whether this declaration is the `revert` keyword.
#[inline]
pub fn is_revert(&self) -> bool {
self.get_css_wide_keyword().map_or(false, |kw| kw == CSSWideKeyword::Revert)
}

/// Returns whether or not the property is set by a system font
pub fn get_system(&self) -> Option<SystemFont> {
match *self {
@@ -3447,22 +3441,16 @@ impl<'a> StyleBuilder<'a> {
}

% for property in data.longhands:
% if property.ident != "font_size":
% if not property.style_struct.inherited:
/// Inherit `${property.ident}` from our parent style.
#[allow(non_snake_case)]
pub fn inherit_${property.ident}(&mut self) {
let inherited_struct =
% if property.style_struct.inherited:
self.inherited_style.get_${property.style_struct.name_lower}();
% else:
self.inherited_style_ignoring_first_line
.get_${property.style_struct.name_lower}();
% endif

% if not property.style_struct.inherited:
self.flags.insert(ComputedValueFlags::INHERITS_RESET_STYLE);
self.modified_reset = true;
% endif
self.flags.insert(ComputedValueFlags::INHERITS_RESET_STYLE);

% if property.ident == "content":
self.flags.insert(ComputedValueFlags::INHERITS_CONTENT);
@@ -3484,17 +3472,13 @@ impl<'a> StyleBuilder<'a> {
% endif
);
}

% elif property.name != "font-size":
/// Reset `${property.ident}` to the initial value.
#[allow(non_snake_case)]
pub fn reset_${property.ident}(&mut self) {
let reset_struct =
self.reset_style.get_${property.style_struct.name_lower}();

% if not property.style_struct.inherited:
self.modified_reset = true;
% endif

if self.${property.style_struct.ident}.ptr_eq(reset_struct) {
return;
}
@@ -3507,6 +3491,7 @@ impl<'a> StyleBuilder<'a> {
% endif
);
}
% endif

% if not property.is_vector:
/// Set the `${property.ident}` to the computed value `value`.
@@ -3528,7 +3513,6 @@ impl<'a> StyleBuilder<'a> {
);
}
% endif
% endif
% endfor
<% del property %>

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