Auto merge of #18053 - bholley:descendants_bit_refactor, r=emilio

Overhaul dirty descendants propagation in preparation for restyle roots

https://bugzilla.mozilla.org/show_bug.cgi?id=1389385

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components/layout_thread/dom_wrapper.rs

@@ -63,14 +63,13 @@ use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem::transmute;
 use std::sync::atomic::Ordering;
-use style;
 use style::CaseSensitivityExt;
 use style::applicable_declarations::ApplicableDeclarationBlock;
 use style::attr::AttrValue;
 use style::computed_values::display;
 use style::context::{QuirksMode, SharedStyleContext};
 use style::data::ElementData;
-use style::dom::{DescendantsBit, DirtyDescendants, LayoutIterator, NodeInfo, OpaqueNode};
+use style::dom::{LayoutIterator, NodeInfo, OpaqueNode};
 use style::dom::{PresentationalHintsSynthesizer, TElement, TNode, UnsafeNode};
 use style::element_state::*;
 use style::font_metrics::ServoMetricsProvider;
@@ -469,11 +468,6 @@ impl<'le> TElement for ServoLayoutElement<'le> {
         self.as_node().node.set_flag(HANDLED_SNAPSHOT, true);
     }
 
-    unsafe fn note_descendants<B: DescendantsBit<Self>>(&self) {
-        debug_assert!(self.get_data().is_some());
-        style::dom::raw_note_descendants::<Self, B>(*self);
-    }
-
     unsafe fn set_dirty_descendants(&self) {
         debug_assert!(self.as_node().node.get_flag(IS_IN_DOC));
         self.as_node().node.set_flag(HAS_DIRTY_DESCENDANTS, true)
@@ -625,12 +619,6 @@ impl<'le> ServoLayoutElement<'le> {
         self.as_node().node.set_flag(HAS_SNAPSHOT, true);
     }
 
-    // FIXME(bholley): This should be merged with TElement::note_descendants,
-    // but that requires re-testing and possibly fixing the broken callers given
-    // the FIXME below, which I don't have time to do right now.
-    //
-    // FIXME(emilio): We'd also need to relax the invariant in note_descendants
-    // re. the data already available I think.
     pub unsafe fn note_dirty_descendant(&self) {
         use ::selectors::Element;
 
@@ -644,8 +632,6 @@ impl<'le> ServoLayoutElement<'le> {
             el.set_dirty_descendants();
             current = el.parent_element();
         }
-
-        debug_assert!(self.descendants_bit_is_propagated::<DirtyDescendants>());
     }
 }
 

components/style/dom.rs

@@ -33,7 +33,6 @@ use std::fmt::Debug;
 use std::hash::Hash;
 use std::ops::Deref;
 use stylist::Stylist;
-use thread_state;
 use traversal_flags::{TraversalFlags, self};
 
 pub use style_traits::UnsafeNode;
@@ -240,44 +239,6 @@ fn fmt_subtree<F, N: TNode>(f: &mut fmt::Formatter, stringify: &F, n: N, indent:
     Ok(())
 }
 
-/// Flag that this element has a descendant for style processing, propagating
-/// the bit up to the root as needed.
-///
-/// This is _not_ safe to call during the parallel traversal.
-///
-/// This is intended as a helper so Servo and Gecko can override it with custom
-/// stuff if needed.
-///
-/// Returns whether no parent had already noted it, that is, whether we reached
-/// the root during the walk up.
-pub unsafe fn raw_note_descendants<E, B>(element: E) -> bool
-    where E: TElement,
-          B: DescendantsBit<E>,
-{
-    debug_assert!(!thread_state::get().is_worker());
-    // TODO(emilio, bholley): Documenting the flags setup a bit better wouldn't
-    // really hurt I guess.
-    debug_assert!(element.get_data().is_some(),
-                  "You should ensure you only flag styled elements");
-
-    let mut curr = Some(element);
-    while let Some(el) = curr {
-        if B::has(el) {
-            break;
-        }
-        B::set(el);
-        curr = el.traversal_parent();
-    }
-
-    // Note: We disable this assertion on servo because of bugs. See the
-    // comment around note_dirty_descendant in layout/wrapper.rs.
-    if cfg!(feature = "gecko") {
-        debug_assert!(element.descendants_bit_is_propagated::<B>());
-    }
-
-    curr.is_none()
-}
-
 /// A trait used to synthesize presentational hints for HTML element attributes.
 pub trait PresentationalHintsSynthesizer {
     /// Generate the proper applicable declarations due to presentational hints,
@@ -501,30 +462,11 @@ pub trait TElement : Eq + PartialEq + Debug + Hash + Sized + Copy + Clone +
         data.has_styles() && !data.restyle.hint.has_non_animation_invalidations()
     }
 
-    /// Flags an element and its ancestors with a given `DescendantsBit`.
-    ///
-    /// TODO(emilio): We call this conservatively from restyle_element_internal
-    /// because we never flag unstyled stuff. A different setup for this may be
-    /// a bit cleaner, but it's probably not worth to invest on it right now
-    /// unless necessary.
-    unsafe fn note_descendants<B: DescendantsBit<Self>>(&self);
-
     /// Flag that this element has a descendant for style processing.
     ///
     /// Only safe to call with exclusive access to the element.
     unsafe fn set_dirty_descendants(&self);
 
-    /// Debug helper to be sure the bit is propagated.
-    fn descendants_bit_is_propagated<B: DescendantsBit<Self>>(&self) -> bool {
-        let mut current = Some(*self);
-        while let Some(el) = current {
-            if !B::has(el) { return false; }
-            current = el.traversal_parent();
-        }
-
-        true
-    }
-
     /// Flag that this element has no descendant for style processing.
     ///
     /// Only safe to call with exclusive access to the element.

components/style/gecko/generated/bindings.rs

@@ -1082,8 +1082,11 @@ extern "C" {
     pub fn Gecko_UnsetNodeFlags(node: RawGeckoNodeBorrowed, flags: u32);
 }
 extern "C" {
-    pub fn Gecko_SetOwnerDocumentNeedsStyleFlush(element:
-                                                     RawGeckoElementBorrowed);
+    pub fn Gecko_NoteDirtyElement(element: RawGeckoElementBorrowed);
+}
+extern "C" {
+    pub fn Gecko_NoteAnimationOnlyDirtyElement(element:
+                                                   RawGeckoElementBorrowed);
 }
 extern "C" {
     pub fn Gecko_GetStyleContext(element: RawGeckoElementBorrowed,