Auto merge of #17348 - emilio:bup, r=bholley

style: Inline RestyleData.

Bug: 1368236
MozReview-Commit-ID: 49s3SO0PMHf

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11 files changed, 183 insertions, 202 deletions

diff --git a/components/layout/wrapper.rs b/components/layout/wrapper.rs
index 4ae7c403e37..87fe65bb3b9 100644
--- a/components/layout/wrapper.rs
+++ b/components/layout/wrapper.rs
@@ -171,19 +171,14 @@ impl<T: ThreadSafeLayoutNode> ThreadSafeLayoutNodeHelpers for T {
 
         let damage = {
             let data = node.get_raw_data().unwrap();
-            if let Some(r) = data.style_data.element_data.borrow().get_restyle() {
-                // We're reflowing a node that just got a restyle, and so the
-                // damage has been computed and stored in the RestyleData.
-                r.damage
-            } else if !data.layout_data.borrow().flags.contains(::data::HAS_BEEN_TRAVERSED) {
+
+            if !data.layout_data.borrow().flags.contains(::data::HAS_BEEN_TRAVERSED) {
                 // We're reflowing a node that was styled for the first time and
                 // has never been visited by layout. Return rebuild_and_reflow,
                 // because that's what the code expects.
                 RestyleDamage::rebuild_and_reflow()
             } else {
-                // We're reflowing a node whose style data didn't change, but whose
-                // layout may change due to changes in ancestors or descendants.
-                RestyleDamage::empty()
+                data.style_data.element_data.borrow().restyle.damage
             }
         };
 
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 7c7b5fd89ed..d53fa05a37f 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -1116,7 +1116,7 @@ impl LayoutThread {
                         let el = node.as_element().unwrap();
                         if let Some(mut d) = element.mutate_data() {
                             if d.has_styles() {
-                                d.ensure_restyle().hint.insert(RestyleHint::restyle_subtree());
+                                d.restyle.hint.insert(RestyleHint::restyle_subtree());
                             }
                         }
                         if let Some(p) = el.parent_element() {
@@ -1152,7 +1152,7 @@ impl LayoutThread {
         if needs_dirtying {
             if let Some(mut d) = element.mutate_data() {
                 if d.has_styles() {
-                    d.ensure_restyle().hint.insert(RestyleHint::restyle_subtree());
+                    d.restyle.hint.insert(RestyleHint::restyle_subtree());
                 }
             }
         }
@@ -1197,12 +1197,11 @@ impl LayoutThread {
             }
 
             let mut style_data = style_data.borrow_mut();
-            let mut restyle_data = style_data.ensure_restyle();
 
             // Stash the data on the element for processing by the style system.
-            restyle_data.hint.insert(restyle.hint.into());
-            restyle_data.damage = restyle.damage;
-            debug!("Noting restyle for {:?}: {:?}", el, restyle_data);
+            style_data.restyle.hint.insert(restyle.hint.into());
+            style_data.restyle.damage = restyle.damage;
+            debug!("Noting restyle for {:?}: {:?}", el, style_data.restyle);
         }
 
         // Create a layout context for use throughout the following passes.
diff --git a/components/style/data.rs b/components/style/data.rs
index 46d9fe8afe0..0363d397d74 100644
--- a/components/style/data.rs
+++ b/components/style/data.rs
@@ -348,17 +348,26 @@ impl ElementStyles {
     }
 }
 
+bitflags! {
+    flags RestyleFlags: u8 {
+        /// Whether the styles changed for this restyle.
+        const WAS_RESTYLED = 1 << 0,
+        /// Whether we reframed/reconstructed any ancestor or self.
+        const ANCESTOR_WAS_RECONSTRUCTED = 1 << 1,
+    }
+}
+
 /// Transient data used by the restyle algorithm. This structure is instantiated
 /// either before or during restyle traversal, and is cleared at the end of node
 /// processing.
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub struct RestyleData {
     /// The restyle hint, which indicates whether selectors need to be rematched
     /// for this element, its children, and its descendants.
     pub hint: RestyleHint,
 
-    /// Whether we reframed/reconstructed any ancestor or self.
-    pub reconstructed_ancestor: bool,
+    /// A few flags to have in mind.
+    flags: RestyleFlags,
 
     /// The restyle damage, indicating what kind of layout changes are required
     /// afte restyling.
@@ -366,9 +375,53 @@ pub struct RestyleData {
 }
 
 impl RestyleData {
-    /// Returns true if this RestyleData might invalidate the current style.
-    pub fn has_invalidations(&self) -> bool {
-        self.hint.has_self_invalidations()
+    fn new() -> Self {
+        Self {
+            hint: RestyleHint::empty(),
+            flags: RestyleFlags::empty(),
+            damage: RestyleDamage::empty(),
+        }
+    }
+
+    /// Clear all the restyle state associated with this element.
+    fn clear(&mut self) {
+        *self = Self::new();
+    }
+
+    /// Returns whether this element or any ancestor is going to be
+    /// reconstructed.
+    pub fn reconstructed_self_or_ancestor(&self) -> bool {
+        self.reconstructed_ancestor() ||
+        self.damage.contains(RestyleDamage::reconstruct())
+    }
+
+    /// Returns whether any ancestor of this element was restyled.
+    fn reconstructed_ancestor(&self) -> bool {
+        self.flags.contains(ANCESTOR_WAS_RECONSTRUCTED)
+    }
+
+    /// Sets the flag that tells us whether we've reconstructed an ancestor.
+    pub fn set_reconstructed_ancestor(&mut self) {
+        // If it weren't for animation-only traversals, we could assert
+        // `!self.reconstructed_ancestor()` here.
+        self.flags.insert(ANCESTOR_WAS_RECONSTRUCTED);
+    }
+
+    /// Mark this element as restyled, which is useful to know whether we need
+    /// to do a post-traversal.
+    pub fn set_restyled(&mut self) {
+        self.flags.insert(WAS_RESTYLED);
+    }
+
+    /// Mark this element as restyled, which is useful to know whether we need
+    /// to do a post-traversal.
+    pub fn is_restyle(&self) -> bool {
+        self.flags.contains(WAS_RESTYLED)
+    }
+
+    /// Returns whether this element has been part of a restyle.
+    pub fn contains_restyle_data(&self) -> bool {
+        self.is_restyle() || !self.hint.is_empty() || !self.damage.is_empty()
     }
 }
 
@@ -382,9 +435,8 @@ pub struct ElementData {
     /// The computed styles for the element and its pseudo-elements.
     styles: Option<ElementStyles>,
 
-    /// Restyle tracking. We separate this into a separate allocation so that
-    /// we can drop it when no restyles are pending on the elemnt.
-    restyle: Option<Box<RestyleData>>,
+    /// Restyle state.
+    pub restyle: RestyleData,
 }
 
 /// The kind of restyle that a single element should do.
@@ -402,6 +454,14 @@ pub enum RestyleKind {
 }
 
 impl ElementData {
+    /// Borrows both styles and restyle mutably at the same time.
+    pub fn styles_and_restyle_mut(
+        &mut self
+    ) -> (&mut ElementStyles, &mut RestyleData) {
+        (self.styles.as_mut().unwrap(),
+         &mut self.restyle)
+    }
+
     /// Invalidates style for this element, its descendants, and later siblings,
     /// based on the snapshot of the element that we took when attributes or
     /// state changed.
@@ -437,7 +497,7 @@ impl ElementData {
     pub fn new(existing: Option<ElementStyles>) -> Self {
         ElementData {
             styles: existing,
-            restyle: None,
+            restyle: RestyleData::new(),
         }
     }
 
@@ -448,7 +508,7 @@ impl ElementData {
 
     /// Returns whether we have any outstanding style invalidation.
     pub fn has_invalidations(&self) -> bool {
-        self.restyle.as_ref().map_or(false, |r| r.has_invalidations())
+        self.restyle.hint.has_self_invalidations()
     }
 
     /// Returns the kind of restyling that we're going to need to do on this
@@ -465,10 +525,7 @@ impl ElementData {
             return RestyleKind::MatchAndCascade;
         }
 
-        debug_assert!(self.restyle.is_some());
-        let restyle_data = self.restyle.as_ref().unwrap();
-
-        let hint = restyle_data.hint;
+        let hint = self.restyle.hint;
         if shared_context.traversal_flags.for_animation_only() {
             // return either CascadeWithReplacements or CascadeOnly in case of
             // animation-only restyle.
@@ -488,7 +545,8 @@ impl ElementData {
             return RestyleKind::CascadeWithReplacements(hint & RestyleHint::replacements());
         }
 
-        debug_assert!(hint.has_recascade_self(), "We definitely need to do something!");
+        debug_assert!(hint.has_recascade_self(),
+                      "We definitely need to do something!");
         return RestyleKind::CascadeOnly;
     }
 
@@ -513,13 +571,6 @@ impl ElementData {
         self.styles.as_mut().expect("Calling styles_mut() on unstyled ElementData")
     }
 
-    /// Borrows both styles and restyle mutably at the same time.
-    pub fn styles_and_restyle_mut(&mut self) -> (&mut ElementStyles,
-                                                 Option<&mut RestyleData>) {
-        (self.styles.as_mut().unwrap(),
-         self.restyle.as_mut().map(|r| &mut **r))
-    }
-
     /// Sets the computed element styles.
     pub fn set_styles(&mut self, styles: ElementStyles) {
         self.styles = Some(styles);
@@ -558,47 +609,9 @@ impl ElementData {
         important_rules != other_important_rules
     }
 
-    /// Returns true if the Element has a RestyleData.
-    pub fn has_restyle(&self) -> bool {
-        self.restyle.is_some()
-    }
-
-    /// Drops any RestyleData.
-    pub fn clear_restyle(&mut self) {
-        self.restyle = None;
-    }
-
-    /// Creates a RestyleData if one doesn't exist.
-    ///
-    /// Asserts that the Element has been styled.
-    pub fn ensure_restyle(&mut self) -> &mut RestyleData {
-        debug_assert!(self.styles.is_some(), "restyling unstyled element");
-        if self.restyle.is_none() {
-            self.restyle = Some(Box::new(RestyleData::default()));
-        }
-        self.restyle.as_mut().unwrap()
-    }
-
-    /// Gets a reference to the restyle data, if any.
-    pub fn get_restyle(&self) -> Option<&RestyleData> {
-        self.restyle.as_ref().map(|r| &**r)
-    }
-
-    /// Gets a reference to the restyle data. Panic if the element does not
-    /// have restyle data.
-    pub fn restyle(&self) -> &RestyleData {
-        self.get_restyle().expect("Calling restyle without RestyleData")
-    }
-
-    /// Gets a mutable reference to the restyle data, if any.
-    pub fn get_restyle_mut(&mut self) -> Option<&mut RestyleData> {
-        self.restyle.as_mut().map(|r| &mut **r)
-    }
-
-    /// Gets a mutable reference to the restyle data. Panic if the element does
-    /// not have restyle data.
-    pub fn restyle_mut(&mut self) -> &mut RestyleData {
-        self.get_restyle_mut().expect("Calling restyle_mut without RestyleData")
+    /// Drops any restyle state from the element.
+    pub fn clear_restyle_state(&mut self) {
+        self.restyle.clear();
     }
 
     /// Returns SMIL overriden value if exists.
diff --git a/components/style/dom.rs b/components/style/dom.rs
index 795eb51c247..769cedfda28 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -567,8 +567,7 @@ pub trait TElement : Eq + PartialEq + Debug + Hash + Sized + Copy + Clone +
             Some(d) => d,
             None => return false,
         };
-        return data.get_restyle()
-                   .map_or(false, |r| r.hint.has_animation_hint());
+        return data.restyle.hint.has_animation_hint()
     }
 
     /// Gets declarations from XBL bindings from the element. Only gecko element could have this.
diff --git a/components/style/invalidation/element/invalidator.rs b/components/style/invalidation/element/invalidator.rs
index df92a4f3a8d..ed759076e23 100644
--- a/components/style/invalidation/element/invalidator.rs
+++ b/components/style/invalidation/element/invalidator.rs
@@ -114,7 +114,7 @@ impl<'a, 'b: 'a, E> TreeStyleInvalidator<'a, 'b, E>
             // We can't just return here because there may also be attribute
             // changes as well that imply additional hints.
             let mut data = self.data.as_mut().unwrap();
-            data.ensure_restyle().hint.insert(RestyleHint::restyle_subtree().into());
+            data.restyle.hint.insert(RestyleHint::restyle_subtree());
         }
 
         let mut classes_removed = SmallVec::<[Atom; 8]>::new();
@@ -211,7 +211,7 @@ impl<'a, 'b: 'a, E> TreeStyleInvalidator<'a, 'b, E>
 
         if invalidated_self {
             if let Some(ref mut data) = self.data {
-                data.ensure_restyle().hint.insert(RESTYLE_SELF.into());
+                data.restyle.hint.insert(RESTYLE_SELF);
             }
         }
 
@@ -287,10 +287,8 @@ impl<'a, 'b: 'a, E> TreeStyleInvalidator<'a, 'b, E>
         match self.data {
             None => return false,
             Some(ref data) => {
-                if let Some(restyle) = data.get_restyle() {
-                    if restyle.hint.contains_subtree() {
-                        return false;
-                    }
+                if data.restyle.hint.contains_subtree() {
+                    return false;
                 }
             }
         }
@@ -494,7 +492,7 @@ impl<'a, 'b: 'a, E> TreeStyleInvalidator<'a, 'b, E>
 
         if invalidated_self {
             if let Some(ref mut data) = self.data {
-                data.ensure_restyle().hint.insert(RESTYLE_SELF.into());
+                data.restyle.hint.insert(RESTYLE_SELF);
             }
         }
 
diff --git a/components/style/invalidation/stylesheets.rs b/components/style/invalidation/stylesheets.rs
index c72a733467c..b28ae6fed87 100644
--- a/components/style/invalidation/stylesheets.rs
+++ b/components/style/invalidation/stylesheets.rs
@@ -134,7 +134,7 @@ impl StylesheetInvalidationSet {
             if self.fully_invalid {
                 debug!("process_invalidations: fully_invalid({:?})",
                        element);
-                data.ensure_restyle().hint.insert(RestyleHint::restyle_subtree());
+                data.restyle.hint.insert(RestyleHint::restyle_subtree());
                 return true;
             }
         }
@@ -165,19 +165,17 @@ impl StylesheetInvalidationSet {
             return false;
         }
 
-        if let Some(ref r) = data.get_restyle() {
-            if r.hint.contains_subtree() {
-                debug!("process_invalidations_in_subtree: {:?} was already invalid",
-                       element);
-                return false;
-            }
+        if data.restyle.hint.contains_subtree() {
+            debug!("process_invalidations_in_subtree: {:?} was already invalid",
+                   element);
+            return false;
         }
 
         for scope in &self.invalid_scopes {
             if scope.matches(element) {
                 debug!("process_invalidations_in_subtree: {:?} matched {:?}",
                        element, scope);
-                data.ensure_restyle().hint.insert(RestyleHint::restyle_subtree());
+                data.restyle.hint.insert(RestyleHint::restyle_subtree());
                 return true;
             }
         }
diff --git a/components/style/matching.rs b/components/style/matching.rs
index 320546147bf..a1cde2f85d5 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -707,8 +707,7 @@ trait PrivateMatchMethods: TElement {
         // for followup work to make the optimization here more optimal by considering
         // each bit individually.
         let skip_applying_damage =
-            restyle.damage.contains(RestyleDamage::reconstruct()) ||
-            restyle.reconstructed_ancestor;
+            restyle.reconstructed_self_or_ancestor();
 
         let difference = self.compute_style_difference(&old_values,
                                                        &new_values,
@@ -1187,12 +1186,10 @@ pub trait MatchMethods : TElement {
             }
         });
 
-        if matches_different_pseudos {
-            if let Some(r) = data.get_restyle_mut() {
-                // Any changes to the matched pseudo-elements trigger
-                // reconstruction.
-                r.damage |= RestyleDamage::reconstruct();
-            }
+        if matches_different_pseudos && data.restyle.is_restyle() {
+            // Any changes to the matched pseudo-elements trigger
+            // reconstruction.
+            data.restyle.damage |= RestyleDamage::reconstruct();
         }
     }
 
@@ -1257,16 +1254,11 @@ pub trait MatchMethods : TElement {
     /// Computes and applies restyle damage.
     fn accumulate_damage(&self,
                          shared_context: &SharedStyleContext,
-                         restyle: Option<&mut RestyleData>,
+                         restyle: &mut RestyleData,
                          old_values: Option<&ComputedValues>,
                          new_values: &Arc<ComputedValues>,
                          pseudo: Option<&PseudoElement>)
                          -> ChildCascadeRequirement {
-        let restyle = match restyle {
-            Some(r) => r,
-            None => return ChildCascadeRequirement::MustCascadeChildren,
-        };
-
         let old_values = match old_values {
             Some(v) => v,
             None => return ChildCascadeRequirement::MustCascadeChildren,
diff --git a/components/style/sharing/mod.rs b/components/style/sharing/mod.rs
index 5971eb34367..a1cedbd4b73 100644
--- a/components/style/sharing/mod.rs
+++ b/components/style/sharing/mod.rs
@@ -377,38 +377,38 @@ impl<E: TElement> StyleSharingTarget<E> {
             // We used to have pseudos (because we had styles).
             // Check for damage from the set of pseudos changing or
             // pseudos being restyled.
-            let (styles, restyle_data) = data.styles_and_restyle_mut();
-            if let Some(restyle_data) = restyle_data {
-                let old_pseudos = &styles.pseudos;
-                let new_pseudos = &shared_style.pseudos;
-                if !old_pseudos.has_same_pseudos_as(new_pseudos) {
-                    restyle_data.damage |= RestyleDamage::reconstruct();
-                } else {
-                    // It's a bit unfortunate that we have to keep
-                    // mapping PseudoElements back to indices
-                    // here....
-                    for pseudo in old_pseudos.keys() {
-                        let old_values =
-                            old_pseudos.get(&pseudo).unwrap().values.as_ref().map(|v| &**v);
-                        let new_values =
-                            new_pseudos.get(&pseudo).unwrap().values();
-                        self.element.accumulate_damage(
-                            &shared_context,
-                            Some(restyle_data),
-                            old_values,
-                            new_values,
-                            Some(&pseudo)
-                        );
-                    }
+            let (styles, mut restyle_data) = data.styles_and_restyle_mut();
+            let old_pseudos = &styles.pseudos;
+            let new_pseudos = &shared_style.pseudos;
+
+            if !old_pseudos.has_same_pseudos_as(new_pseudos) {
+                restyle_data.damage |= RestyleDamage::reconstruct();
+            } else {
+                // It's a bit unfortunate that we have to keep
+                // mapping PseudoElements back to indices
+                // here....
+                for pseudo in old_pseudos.keys() {
+                    let old_values =
+                        old_pseudos.get(&pseudo).unwrap().values.as_ref().map(|v| &**v);
+                    let new_values =
+                        new_pseudos.get(&pseudo).unwrap().values();
+                    self.element.accumulate_damage(
+                        &shared_context,
+                        restyle_data,
+                        old_values,
+                        new_values,
+                        Some(&pseudo)
+                    );
                 }
             }
         }
 
-        let old_values = data.get_styles_mut()
-                             .and_then(|s| s.primary.values.take());
+        let old_values =
+            data.get_styles_mut().and_then(|s| s.primary.values.take());
+
         self.element.accumulate_damage(
             &shared_context,
-            data.get_restyle_mut(),
+            &mut data.restyle,
             old_values.as_ref().map(|v| &**v),
             shared_style.primary.values(),
             None
@@ -597,9 +597,6 @@ impl<E: TElement> StyleSharingCandidateCache<E> {
             match sharing_result {
                 Ok(shared_style) => {
                     // Yay, cache hit. Share the style.
-
-                    debug_assert_eq!(data.has_styles(), data.has_restyle());
-
                     let child_cascade_requirement =
                         target.accumulate_damage_when_sharing(shared_context,
                                                               &shared_style,
diff --git a/components/style/traversal.rs b/components/style/traversal.rs
index 9f085cfe374..004c2485afd 100644
--- a/components/style/traversal.rs
+++ b/components/style/traversal.rs
@@ -10,7 +10,6 @@ use data::{ElementData, ElementStyles};
 use dom::{DirtyDescendants, NodeInfo, OpaqueNode, TElement, TNode};
 use invalidation::element::restyle_hints::{RECASCADE_SELF, RECASCADE_DESCENDANTS, RestyleHint};
 use matching::{ChildCascadeRequirement, MatchMethods};
-use selector_parser::RestyleDamage;
 use sharing::{StyleSharingBehavior, StyleSharingTarget};
 #[cfg(feature = "servo")] use servo_config::opts;
 use smallvec::SmallVec;
@@ -296,10 +295,8 @@ pub trait DomTraversal<E: TElement> : Sync {
         if el.is_native_anonymous() {
             if let Some(parent) = el.traversal_parent() {
                 let parent_data = parent.borrow_data().unwrap();
-                let going_to_reframe = parent_data.get_restyle().map_or(false, |r| {
-                    r.reconstructed_ancestor ||
-                    r.damage.contains(RestyleDamage::reconstruct())
-                });
+                let going_to_reframe =
+                    parent_data.restyle.reconstructed_self_or_ancestor();
 
                 let mut is_before_or_after_pseudo = false;
                 if let Some(pseudo) = el.implemented_pseudo_element() {
@@ -337,9 +334,8 @@ pub trait DomTraversal<E: TElement> : Sync {
                 Some(d) => d,
                 None => return false,
             };
-            return data.get_restyle()
-                       .map_or(false, |r| r.hint.has_animation_hint() ||
-                                          r.hint.has_recascade_self());
+            return data.restyle.hint.has_animation_hint() ||
+                   data.restyle.hint.has_recascade_self();
         }
 
         // If the dirty descendants bit is set, we need to traverse no
@@ -360,18 +356,15 @@ pub trait DomTraversal<E: TElement> : Sync {
             return true;
         }
 
-        // Check the restyle data.
-        if let Some(r) = data.get_restyle() {
-            // If we have a restyle hint or need to recascade, we need to
-            // visit the element.
-            //
-            // Note that this is different than checking has_current_styles(),
-            // since that can return true even if we have a restyle hint
-            // indicating that the element's descendants (but not necessarily
-            // the element) need restyling.
-            if !r.hint.is_empty() {
-                return true;
-            }
+        // If we have a restyle hint or need to recascade, we need to
+        // visit the element.
+        //
+        // Note that this is different than checking has_current_styles(),
+        // since that can return true even if we have a restyle hint
+        // indicating that the element's descendants (but not necessarily
+        // the element) need restyling.
+        if !data.restyle.hint.is_empty() {
+            return true;
         }
 
         // Servo uses the post-order traversal for flow construction, so
@@ -381,7 +374,7 @@ pub trait DomTraversal<E: TElement> : Sync {
         // We also need to traverse nodes with explicit damage and no other
         // restyle data, so that this damage can be cleared.
         if (cfg!(feature = "servo") || traversal_flags.for_reconstruct()) &&
-           data.get_restyle().map_or(false, |r| !r.damage.is_empty()) {
+           !data.restyle.damage.is_empty() {
             return true;
         }
 
@@ -690,20 +683,17 @@ pub fn recalc_style_at<E, D>(traversal: &D,
 
     // Now that matching and cascading is done, clear the bits corresponding to
     // those operations and compute the propagated restyle hint.
-    let mut propagated_hint = match data.get_restyle_mut() {
-        None => RestyleHint::empty(),
-        Some(r) => {
-            debug_assert!(context.shared.traversal_flags.for_animation_only() ||
-                          !r.hint.has_animation_hint(),
-                          "animation restyle hint should be handled during \
-                           animation-only restyles");
-            r.hint.propagate(&context.shared.traversal_flags)
-        },
+    let mut propagated_hint = {
+        debug_assert!(context.shared.traversal_flags.for_animation_only() ||
+                      !data.restyle.hint.has_animation_hint(),
+                      "animation restyle hint should be handled during \
+                       animation-only restyles");
+        data.restyle.hint.propagate(&context.shared.traversal_flags)
     };
 
     // FIXME(bholley): Need to handle explicitly-inherited reset properties
     // somewhere.
-    propagated_hint.insert(hint.into());
+    propagated_hint.insert(hint);
 
     trace!("propagated_hint={:?} \
             is_display_none={:?}, implementing_pseudo={:?}",
@@ -730,10 +720,9 @@ pub fn recalc_style_at<E, D>(traversal: &D,
                                           DontLog) &&
         (has_dirty_descendants_for_this_restyle ||
          !propagated_hint.is_empty()) {
-        let reconstructed_ancestor = data.get_restyle().map_or(false, |r| {
-            r.reconstructed_ancestor ||
-            r.damage.contains(RestyleDamage::reconstruct())
-        });
+        let reconstructed_ancestor =
+            data.restyle.reconstructed_self_or_ancestor();
+
         preprocess_children::<E, D>(
             context,
             element,
@@ -746,7 +735,7 @@ pub fn recalc_style_at<E, D>(traversal: &D,
     // data here, since we won't need to perform a post-traversal to pick up
     // any change hints.
     if context.shared.traversal_flags.for_reconstruct() {
-        data.clear_restyle();
+        data.clear_restyle_state();
     }
 
     if context.shared.traversal_flags.for_animation_only() {
@@ -792,6 +781,10 @@ fn compute_style<E, D>(_traversal: &D,
 
     debug!("compute_style: {:?} (kind={:?})", element, kind);
 
+    if data.has_styles() {
+        data.restyle.set_restyled();
+    }
+
     match kind {
         MatchAndCascade => {
             debug_assert!(!context.shared.traversal_flags.for_animation_only(),
@@ -870,31 +863,24 @@ where
             continue;
         }
 
-        // Handle element snapshots and invalidation of descendants and siblings
-        // as needed.
-        //
-        // NB: This will be a no-op if there's no restyle data and no snapshot.
-        child_data.invalidate_style_if_needed(child, &context.shared);
-
         trace!(" > {:?} -> {:?} + {:?}, pseudo: {:?}",
                child,
-               child_data.get_restyle().map(|r| &r.hint),
+               child_data.restyle.hint,
                propagated_hint,
                child.implemented_pseudo_element());
 
-        // If the child doesn't have pre-existing RestyleData and we don't have
-        // any reason to create one, avoid the useless allocation and move on to
-        // the next child.
-        if !reconstructed_ancestor && propagated_hint.is_empty() && !child_data.has_restyle() {
-            continue;
-        }
-
-        let mut restyle_data = child_data.ensure_restyle();
-
         // Propagate the parent restyle hint, that may make us restyle the whole
         // subtree.
-        restyle_data.reconstructed_ancestor = reconstructed_ancestor;
-        restyle_data.hint.insert(propagated_hint);
+        if reconstructed_ancestor {
+            child_data.restyle.set_reconstructed_ancestor();
+        }
+        child_data.restyle.hint.insert(propagated_hint);
+
+        // Handle element snapshots and invalidation of descendants and siblings
+        // as needed.
+        //
+        // NB: This will be a no-op if there's no snapshot.
+        child_data.invalidate_style_if_needed(child, &context.shared);
     }
 }
 
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 19950db47cf..9d8f068be35 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -301,7 +301,7 @@ pub extern "C" fn Servo_TraverseSubtree(root: RawGeckoElementBorrowed,
         return false;
     }
 
-    element.has_dirty_descendants() || element.borrow_data().unwrap().has_restyle()
+    element.has_dirty_descendants() || element.borrow_data().unwrap().restyle.contains_restyle_data()
 }
 
 #[no_mangle]
@@ -2461,7 +2461,7 @@ unsafe fn maybe_restyle<'a>(data: &'a mut AtomicRefMut<ElementData>,
     bindings::Gecko_SetOwnerDocumentNeedsStyleFlush(element.0);
 
     // Ensure and return the RestyleData.
-    Some(data.ensure_restyle())
+    Some(&mut data.restyle)
 }
 
 #[no_mangle]
@@ -2518,13 +2518,16 @@ pub extern "C" fn Servo_NoteExplicitHints(element: RawGeckoElementBorrowed,
 pub extern "C" fn Servo_TakeChangeHint(element: RawGeckoElementBorrowed) -> nsChangeHint
 {
     let element = GeckoElement(element);
-    let damage = if let Some(mut data) = element.mutate_data() {
-        let d = data.get_restyle().map_or(GeckoRestyleDamage::empty(), |r| r.damage);
-        data.clear_restyle();
-        d
-    } else {
-        warn!("Trying to get change hint from unstyled element");
-        GeckoRestyleDamage::empty()
+    let damage = match element.mutate_data() {
+        Some(mut data) => {
+            let damage = data.restyle.damage;
+            data.clear_restyle_state();
+            damage
+        }
+        None => {
+            warn!("Trying to get change hint from unstyled element");
+            GeckoRestyleDamage::empty()
+        }
     };
 
     debug!("Servo_TakeChangeHint: {:?}, damage={:?}", element, damage);
diff --git a/tests/unit/stylo/size_of.rs b/tests/unit/stylo/size_of.rs
index d863cb816a8..633180d3289 100644
--- a/tests/unit/stylo/size_of.rs
+++ b/tests/unit/stylo/size_of.rs
@@ -7,7 +7,7 @@ use servo_arc::Arc;
 use std::mem::{size_of, align_of};
 use style;
 use style::applicable_declarations::ApplicableDeclarationBlock;
-use style::data::{ComputedStyle, ElementData, ElementStyles};
+use style::data::{ComputedStyle, ElementData, ElementStyles, RestyleData};
 use style::gecko::selector_parser as real;
 use style::properties::ComputedValues;
 use style::rule_tree::{RuleNode, StrongRuleNode};
@@ -34,6 +34,7 @@ size_of_test!(test_size_of_option_rule_node, Option<StrongRuleNode>, 8);
 size_of_test!(test_size_of_computed_style, ComputedStyle, 32);
 size_of_test!(test_size_of_element_styles, ElementStyles, 48);
 size_of_test!(test_size_of_element_data, ElementData, 56);
+size_of_test!(test_size_of_restyle_data, RestyleData, 8);
 
 size_of_test!(test_size_of_property_declaration, style::properties::PropertyDeclaration, 32);