From 5cbb81a0df8d6f24732fe5aa1c5c0f6a62fee412 Mon Sep 17 00:00:00 2001
From: David Shin <dshin@mozilla.com>
Date: Mon, 17 Oct 2022 17:26:13 +0000
Subject: [PATCH] style: Flag computed styles of elements with `container-type:
 *size` set & propagate them to their descendants

Low-hanging fruit optimization that enables short-circuit exit of container query lookups.

Differential Revision: https://phabricator.services.mozilla.com/D158056
---
 .../style/properties/computed_value_flags.rs      |  7 ++++++-
 components/style/style_adjuster.rs                | 15 +++++++++++----
 components/style/values/specified/box.rs          |  7 +++++++
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/components/style/properties/computed_value_flags.rs b/components/style/properties/computed_value_flags.rs
index 01c23ba73ad..1cfaee084df 100644
--- a/components/style/properties/computed_value_flags.rs
+++ b/components/style/properties/computed_value_flags.rs
@@ -101,6 +101,10 @@ bitflags! {
 
         /// Whether the style depends on viewport units.
         const USES_VIEWPORT_UNITS = 1 << 20;
+
+        /// A flag used to mark styles which have `container-type` of `size` or
+        /// `inline-size`, or under one.
+        const SELF_OR_ANCESTOR_HAS_SIZE_CONTAINER_TYPE = 1 << 21;
     }
 }
 
@@ -113,7 +117,8 @@ impl ComputedValueFlags {
             Self::IS_IN_PSEUDO_ELEMENT_SUBTREE |
             Self::HAS_TEXT_DECORATION_LINES |
             Self::IS_IN_OPACITY_ZERO_SUBTREE |
-            Self::SELF_OR_ANCESTOR_HAS_CONTAIN_STYLE
+            Self::SELF_OR_ANCESTOR_HAS_CONTAIN_STYLE |
+            Self::SELF_OR_ANCESTOR_HAS_SIZE_CONTAINER_TYPE
     }
 
     /// Flags that may be propagated to descendants.
diff --git a/components/style/style_adjuster.rs b/components/style/style_adjuster.rs
index 3305b757292..2912f0676b6 100644
--- a/components/style/style_adjuster.rs
+++ b/components/style/style_adjuster.rs
@@ -250,7 +250,8 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
 
     /// Compute a few common flags for both text and element's style.
     fn set_bits(&mut self) {
-        let display = self.style.get_box().clone_display();
+        let box_style = self.style.get_box();
+        let display = box_style.clone_display();
 
         if !display.is_contents() {
             if !self
@@ -280,9 +281,7 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         }
 
         #[cfg(feature = "gecko")]
-        if self
-            .style
-            .get_box()
+        if box_style
             .clone_contain()
             .contains(SpecifiedValue::STYLE)
         {
@@ -290,6 +289,14 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
                 .add_flags(ComputedValueFlags::SELF_OR_ANCESTOR_HAS_CONTAIN_STYLE);
         }
 
+        if box_style
+            .clone_container_type()
+            .is_size_container_type()
+        {
+            self.style
+                .add_flags(ComputedValueFlags::SELF_OR_ANCESTOR_HAS_SIZE_CONTAINER_TYPE);
+        }
+
         if self.style.get_parent_column().is_multicol() {
             self.style.add_flags(ComputedValueFlags::CAN_BE_FRAGMENTED);
         }
diff --git a/components/style/values/specified/box.rs b/components/style/values/specified/box.rs
index 0faf01bc778..9e8c3e85340 100644
--- a/components/style/values/specified/box.rs
+++ b/components/style/values/specified/box.rs
@@ -1509,6 +1509,13 @@ bitflags! {
     }
 }
 
+impl ContainerType {
+    /// Is this type containing size in any way?
+    pub fn is_size_container_type(&self) -> bool {
+        self.intersects(ContainerType::SIZE | ContainerType::INLINE_SIZE)
+    }
+}
+
 /// https://drafts.csswg.org/css-contain-3/#container-name
 #[repr(transparent)]
 #[derive(