layout: Cache IndependentNonReplacedContents::layout() (#36082)

This replaces `IndependentLayout` with `CacheableLayoutResult` and
stores it in `LayoutBoxBase` so it can be reused when we need to lay out
a box multiple times.

This is a generalization of the caching that we had for flexbox, which
is now removed in favor of the new one.

With this, the number of runs per second in the Chromium perf test
`flexbox-deeply-nested-column-flow.html` are multiplied by 3.

Signed-off-by: Oriol Brufau <obrufau@igalia.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>

components/layout_2020/flow/mod.rs

@@ -26,7 +26,7 @@ use crate::flow::float::{
 };
 use crate::formatting_contexts::{
     Baselines, IndependentFormattingContext, IndependentFormattingContextContents,
-    IndependentLayout, IndependentLayoutResult, IndependentNonReplacedContents,
+    IndependentNonReplacedContents,
 };
 use crate::fragment_tree::{
     BaseFragmentInfo, BoxFragment, CollapsedBlockMargins, CollapsedMargin, Fragment, FragmentFlags,
@@ -35,7 +35,7 @@ use crate::geom::{
     AuOrAuto, LogicalRect, LogicalSides, LogicalSides1D, LogicalVec2, PhysicalPoint, PhysicalRect,
     PhysicalSides, Size, Sizes, ToLogical, ToLogicalWithContainingBlock,
 };
-use crate::layout_box_base::LayoutBoxBase;
+use crate::layout_box_base::{CacheableLayoutResult, LayoutBoxBase};
 use crate::positioned::{AbsolutelyPositionedBox, PositioningContext, PositioningContextLength};
 use crate::replaced::ReplacedContents;
 use crate::sizing::{self, ComputeInlineContentSizes, ContentSizes, InlineContentSizesResult};
@@ -219,18 +219,6 @@ impl BlockLevelBox {
     }
 }
 
-pub(crate) struct FlowLayout {
-    pub fragments: Vec<Fragment>,
-    pub content_block_size: Au,
-    pub collapsible_margins_in_children: CollapsedBlockMargins,
-    /// The offset of the baselines in this layout in the content area, if there were some. This is
-    /// used to propagate inflow baselines to the ancestors of `display: inline-block` elements
-    /// and table content.
-    pub baselines: Baselines,
-    /// Whether or not this layout depends on the block size of its containing block.
-    pub depends_on_block_constraints: bool,
-}
-
 #[derive(Clone, Copy)]
 pub(crate) struct CollapsibleWithParentStartMargin(bool);
 
@@ -362,7 +350,8 @@ impl BlockFormattingContext {
         layout_context: &LayoutContext,
         positioning_context: &mut PositioningContext,
         containing_block: &ContainingBlock,
-    ) -> IndependentLayout {
+        depends_on_block_constraints: bool,
+    ) -> CacheableLayoutResult {
         let mut sequential_layout_state = if self.contains_floats || !layout_context.use_rayon {
             Some(SequentialLayoutState::new(containing_block.size.inline))
         } else {
@@ -395,15 +384,17 @@ impl BlockFormattingContext {
             sequential_layout_state.calculate_clearance(Clear::Both, &CollapsedMargin::zero())
         });
 
-        IndependentLayout {
+        CacheableLayoutResult {
             fragments: flow_layout.fragments,
             content_block_size: flow_layout.content_block_size +
                 flow_layout.collapsible_margins_in_children.end.solve() +
                 clearance.unwrap_or_default(),
             content_inline_size_for_table: None,
             baselines: flow_layout.baselines,
-            depends_on_block_constraints: flow_layout.depends_on_block_constraints,
+            depends_on_block_constraints: depends_on_block_constraints ||
+                flow_layout.depends_on_block_constraints,
             specific_layout_info: None,
+            collapsible_margins_in_children: CollapsedBlockMargins::zero(),
         }
     }
 
@@ -573,7 +564,7 @@ impl BlockContainer {
         sequential_layout_state: Option<&mut SequentialLayoutState>,
         collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
         ignore_block_margins_for_stretch: LogicalSides1D<bool>,
-    ) -> FlowLayout {
+    ) -> CacheableLayoutResult {
         match self {
             BlockContainer::BlockLevelBoxes(child_boxes) => layout_block_level_children(
                 layout_context,
@@ -627,7 +618,7 @@ fn layout_block_level_children(
     mut sequential_layout_state: Option<&mut SequentialLayoutState>,
     collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
     ignore_block_margins_for_stretch: LogicalSides1D<bool>,
-) -> FlowLayout {
+) -> CacheableLayoutResult {
     let mut placement_state =
         PlacementState::new(collapsible_with_parent_start_margin, containing_block);
 
@@ -660,12 +651,14 @@ fn layout_block_level_children(
     });
 
     let (content_block_size, collapsible_margins_in_children, baselines) = placement_state.finish();
-    FlowLayout {
+    CacheableLayoutResult {
         fragments,
         content_block_size,
         collapsible_margins_in_children,
         baselines,
         depends_on_block_constraints,
+        content_inline_size_for_table: None,
+        specific_layout_info: None,
     }
 }
 
@@ -1150,6 +1143,7 @@ impl IndependentNonReplacedContents {
             positioning_context,
             &containing_block_for_children,
             containing_block,
+            false, /* depends_on_block_constraints */
         );
 
         let inline_size = layout
@@ -1299,7 +1293,7 @@ impl IndependentNonReplacedContents {
             )
         };
 
-        let compute_block_size = |layout: &IndependentLayout| {
+        let compute_block_size = |layout: &CacheableLayoutResult| {
             content_box_sizes.block.resolve(
                 Direction::Block,
                 Size::FitContent,
@@ -1335,6 +1329,7 @@ impl IndependentNonReplacedContents {
                     style,
                 },
                 containing_block,
+                false, /* depends_on_block_constraints */
             );
 
             content_size = LogicalVec2 {
@@ -1398,6 +1393,7 @@ impl IndependentNonReplacedContents {
                         style,
                     },
                     containing_block,
+                    false, /* depends_on_block_constraints */
                 );
 
                 let inline_size = if let Some(inline_size) = layout.content_inline_size_for_table {
@@ -2162,6 +2158,12 @@ fn block_size_is_zero_or_intrinsic(size: &StyleSize, containing_block: &Containi
     }
 }
 
+pub(crate) struct IndependentFloatOrAtomicLayoutResult {
+    pub fragment: BoxFragment,
+    pub baselines: Option<Baselines>,
+    pub pbm_sums: LogicalSides<Au>,
+}
+
 impl IndependentFormattingContext {
     pub(crate) fn layout_in_flow_block_level(
         &self,
@@ -2196,7 +2198,7 @@ impl IndependentFormattingContext {
         layout_context: &LayoutContext,
         child_positioning_context: &mut PositioningContext,
         containing_block: &ContainingBlock,
-    ) -> IndependentLayoutResult {
+    ) -> IndependentFloatOrAtomicLayoutResult {
         let style = self.style();
         let container_writing_mode = containing_block.style.writing_mode;
         let layout_style = self.layout_style();
@@ -2280,6 +2282,7 @@ impl IndependentFormattingContext {
                     child_positioning_context,
                     &containing_block_for_children,
                     containing_block,
+                    false, /* depends_on_block_constraints */
                 );
                 let inline_size = independent_layout
                     .content_inline_size_for_table
@@ -2330,7 +2333,7 @@ impl IndependentFormattingContext {
             CollapsedBlockMargins::zero(),
         );
 
-        IndependentLayoutResult {
+        IndependentFloatOrAtomicLayoutResult {
             fragment,
             baselines,
             pbm_sums,