LibWeb: Add opt-in tracing of update_layout() calls with reason

Author: https://github.com/awesomekling
Commit: c333042e63
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3852

Libraries/LibWeb/DOM/Document.cpp

@@ -458,7 +458,7 @@ Document::Document(JS::Realm& realm, const URL::URL& url, TemporaryDocumentForFr
         if (!navigable || !navigable->is_focused())
             return;
 
-        node->document().update_layout();
+        node->document().update_layout(UpdateLayoutReason::CursorBlinkTimer);
 
         if (node->paintable()) {
             m_cursor_blink_state = !m_cursor_blink_state;
@@ -1278,7 +1278,7 @@ static void propagate_overflow_to_viewport(Element& root_element, Layout::Viewpo
     overflow_origin_computed_values.set_overflow_y(CSS::Overflow::Visible);
 }
 
-void Document::update_layout()
+void Document::update_layout(UpdateLayoutReason reason)
 {
     auto navigable = this->navigable();
     if (!navigable || navigable->active_document() != this)
@@ -1287,7 +1287,7 @@ void Document::update_layout()
     // NOTE: If our parent document needs a relayout, we must do that *first*.
     //       This is necessary as the parent layout may cause our viewport to change.
     if (navigable->container() && &navigable->container()->document() != this)
-        navigable->container()->document().update_layout();
+        navigable->container()->document().update_layout(reason);
 
     update_style();
 
@@ -1303,6 +1303,8 @@ void Document::update_layout()
     auto* document_element = this->document_element();
     auto viewport_rect = navigable->viewport_rect();
 
+    auto timer = Core::ElapsedTimer::start_new(Core::TimerType::Precise);
+
     if (!m_layout_root || needs_layout_tree_update() || child_needs_layout_tree_update() || needs_full_layout_tree_update()) {
         Layout::TreeBuilder tree_builder;
         m_layout_root = as<Layout::Viewport>(*tree_builder.build(*this));
@@ -1313,6 +1315,10 @@ void Document::update_layout()
         }
 
         set_needs_full_layout_tree_update(false);
+
+        if constexpr (UPDATE_LAYOUT_DEBUG) {
+            dbgln("TREEBUILD {} µs", timer.elapsed_time().to_microseconds());
+        }
     }
 
     // Assign each box that establishes a formatting context a list of absolutely positioned children it should take care of during layout
@@ -1388,6 +1394,10 @@ void Document::update_layout()
     // after the viewport size change.
     if (auto window = this->window())
         window->scroll_by(0, 0);
+
+    if constexpr (UPDATE_LAYOUT_DEBUG) {
+        dbgln("LAYOUT {} {} µs", to_string(reason), timer.elapsed_time().to_microseconds());
+    }
 }
 
 [[nodiscard]] static CSS::RequiredInvalidationAfterStyleChange update_style_recursively(Node& node, CSS::StyleComputer& style_computer, bool needs_inherited_style_update)
@@ -5405,7 +5415,7 @@ WebIDL::ExceptionOr<void> Document::set_design_mode(String const& design_mode)
             if (auto active_range = selection->range(); active_range) {
                 TRY(active_range->set_start(*this, 0));
                 TRY(active_range->set_end(*this, 0));
-                update_layout();
+                update_layout(UpdateLayoutReason::DocumentSetDesignMode);
             }
         }
         // 3. Run the focusing steps for this's document element, if non-null.
@@ -5432,7 +5442,7 @@ Element const* Document::element_from_point(double x, double y)
         return nullptr;
 
     // Ensure the layout tree exists prior to hit testing.
-    update_layout();
+    update_layout(UpdateLayoutReason::DocumentElementFromPoint);
 
     // 2. If there is a box in the viewport that would be a target for hit testing at coordinates x,y, when applying the transforms
     //    that apply to the descendants of the viewport, return the associated element and terminate these steps.
@@ -5474,7 +5484,7 @@ GC::RootVector<GC::Ref<Element>> Document::elements_from_point(double x, double
         return sequence;
 
     // Ensure the layout tree exists prior to hit testing.
-    update_layout();
+    update_layout(UpdateLayoutReason::DocumentElementsFromPoint);
 
     // 3. For each box in the viewport, in paint order, starting with the topmost box, that would be a target for
     //    hit testing at coordinates x,y even if nothing would be overlapping it, when applying the transforms that
@@ -6002,7 +6012,7 @@ void Document::set_needs_to_refresh_scroll_state(bool b)
 Vector<GC::Root<DOM::Range>> Document::find_matching_text(String const& query, CaseSensitivity case_sensitivity)
 {
     // Ensure the layout tree exists before searching for text matches.
-    update_layout();
+    update_layout(UpdateLayoutReason::DocumentFindMatchingText);
 
     if (!layout_node())
         return {};
@@ -6393,4 +6403,16 @@ void Document::set_onvisibilitychange(WebIDL::CallbackType* value)
     set_event_handler_attribute(HTML::EventNames::visibilitychange, value);
 }
 
+StringView to_string(UpdateLayoutReason reason)
+{
+    switch (reason) {
+#define ENUMERATE_UPDATE_LAYOUT_REASON(e) \
+    case UpdateLayoutReason::e:           \
+        return #e##sv;
+        ENUMERATE_UPDATE_LAYOUT_REASONS(ENUMERATE_UPDATE_LAYOUT_REASON)
+#undef ENUMERATE_UPDATE_LAYOUT_REASON
+    }
+    VERIFY_NOT_REACHED();
+}
+
 }

Libraries/LibWeb/DOM/Document.h

@@ -50,6 +50,64 @@ enum class QuirksMode {
     Yes
 };
 
+#define ENUMERATE_UPDATE_LAYOUT_REASONS(X) \
+    X(CanvasRenderingContext2DSetFilter)   \
+    X(CursorBlinkTimer)                    \
+    X(Debugging)                           \
+    X(DocumentElementFromPoint)            \
+    X(DocumentElementsFromPoint)           \
+    X(DocumentFindMatchingText)            \
+    X(DocumentSetDesignMode)               \
+    X(ElementCheckVisibility)              \
+    X(ElementClientHeight)                 \
+    X(ElementClientLeft)                   \
+    X(ElementClientTop)                    \
+    X(ElementClientWidth)                  \
+    X(ElementGetClientRects)               \
+    X(ElementIsPotentiallyScrollable)      \
+    X(ElementScroll)                       \
+    X(ElementScrollHeight)                 \
+    X(ElementScrollIntoView)               \
+    X(ElementScrollLeft)                   \
+    X(ElementScrollTop)                    \
+    X(ElementScrollWidth)                  \
+    X(ElementSetScrollLeft)                \
+    X(ElementSetScrollTop)                 \
+    X(EventHandlerHandleDoubleClick)       \
+    X(EventHandlerHandleDragAndDrop)       \
+    X(EventHandlerHandleMouseDown)         \
+    X(EventHandlerHandleMouseMove)         \
+    X(EventHandlerHandleMouseUp)           \
+    X(EventHandlerHandleMouseWheel)        \
+    X(HTMLElementGetTheTextSteps)          \
+    X(HTMLElementOffsetHeight)             \
+    X(HTMLElementOffsetLeft)               \
+    X(HTMLElementOffsetParent)             \
+    X(HTMLElementOffsetTop)                \
+    X(HTMLElementOffsetWidth)              \
+    X(HTMLEventLoopRenderingUpdate)        \
+    X(HTMLImageElementHeight)              \
+    X(HTMLImageElementWidth)               \
+    X(HTMLInputElementHeight)              \
+    X(HTMLInputElementWidth)               \
+    X(InternalsHitTest)                    \
+    X(MediaQueryListMatches)               \
+    X(NodeNameOrDescription)               \
+    X(RangeGetClientRects)                 \
+    X(ResolvedCSSStyleDeclarationProperty) \
+    X(SVGDecodedImageDataRender)           \
+    X(SVGGraphicsElementGetBBox)           \
+    X(SourceSetNormalizeSourceDensities)   \
+    X(WindowScroll)
+
+enum class UpdateLayoutReason {
+#define ENUMERATE_UPDATE_LAYOUT_REASON(e) e,
+    ENUMERATE_UPDATE_LAYOUT_REASONS(ENUMERATE_UPDATE_LAYOUT_REASON)
+#undef ENUMERATE_UPDATE_LAYOUT_REASON
+};
+
+[[nodiscard]] StringView to_string(UpdateLayoutReason);
+
 // https://html.spec.whatwg.org/multipage/dom.html#document-load-timing-info
 struct DocumentLoadTimingInfo {
     // https://html.spec.whatwg.org/multipage/dom.html#navigation-start-time
@@ -258,7 +316,7 @@ public:
     void obtain_theme_color();
 
     void update_style();
-    void update_layout();
+    void update_layout(UpdateLayoutReason);
     void update_paint_and_hit_testing_properties_if_needed();
     void update_animated_style_if_needed();
 

Libraries/LibWeb/DOM/Element.cpp

@@ -994,7 +994,7 @@ GC::Ref<Geometry::DOMRectList> Element::get_client_rects() const
         return Geometry::DOMRectList::create(realm(), {});
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document()).update_layout();
+    const_cast<Document&>(document()).update_layout(UpdateLayoutReason::ElementGetClientRects);
 
     // 1. If the element on which it was invoked does not have an associated layout box return an empty DOMRectList
     //    object and stop this algorithm.
@@ -1047,7 +1047,7 @@ GC::Ref<Geometry::DOMRectList> Element::get_client_rects() const
 int Element::client_top() const
 {
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document()).update_layout();
+    const_cast<Document&>(document()).update_layout(UpdateLayoutReason::ElementClientTop);
 
     // 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
     if (!paintable_box())
@@ -1063,7 +1063,7 @@ int Element::client_top() const
 int Element::client_left() const
 {
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document()).update_layout();
+    const_cast<Document&>(document()).update_layout(UpdateLayoutReason::ElementClientLeft);
 
     // 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
     if (!paintable_box())
@@ -1089,7 +1089,7 @@ int Element::client_width() const
     }
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document()).update_layout();
+    const_cast<Document&>(document()).update_layout(UpdateLayoutReason::ElementClientWidth);
 
     // 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
     if (!paintable_box())
@@ -1114,7 +1114,7 @@ int Element::client_height() const
     }
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document()).update_layout();
+    const_cast<Document&>(document()).update_layout(UpdateLayoutReason::ElementClientHeight);
 
     // 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
     if (!paintable_box())
@@ -1420,7 +1420,7 @@ void Element::set_tab_index(i32 tab_index)
 bool Element::is_potentially_scrollable() const
 {
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document()).update_layout();
+    const_cast<Document&>(document()).update_layout(UpdateLayoutReason::ElementIsPotentiallyScrollable);
 
     // An element body (which will be the body element) is potentially scrollable if all of the following conditions are true:
     VERIFY(is<HTML::HTMLBodyElement>(this) || is<HTML::HTMLFrameSetElement>(this));
@@ -1466,7 +1466,7 @@ double Element::scroll_top() const
         return window->scroll_y();
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document).update_layout();
+    const_cast<Document&>(document).update_layout(UpdateLayoutReason::ElementScrollTop);
 
     // 7. If the element is the body element, document is in quirks mode, and the element is not potentially scrollable, return the value of scrollY on window.
     if (document.body() == this && document.in_quirks_mode() && !is_potentially_scrollable())
@@ -1508,7 +1508,7 @@ double Element::scroll_left() const
         return window->scroll_x();
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document).update_layout();
+    const_cast<Document&>(document).update_layout(UpdateLayoutReason::ElementScrollLeft);
 
     // 7. If the element is the body element, document is in quirks mode, and the element is not potentially scrollable, return the value of scrollX on window.
     if (document.body() == this && document.in_quirks_mode() && !is_potentially_scrollable())
@@ -1557,7 +1557,7 @@ void Element::set_scroll_left(double x)
     }
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics or scrolling the page.
-    const_cast<Document&>(document).update_layout();
+    const_cast<Document&>(document).update_layout(UpdateLayoutReason::ElementSetScrollLeft);
 
     // 9. If the element is the body element, document is in quirks mode, and the element is not potentially scrollable, invoke scroll() on window with x as first argument and scrollY on window as second argument, and terminate these steps.
     if (document.body() == this && document.in_quirks_mode() && !is_potentially_scrollable()) {
@@ -1614,7 +1614,7 @@ void Element::set_scroll_top(double y)
     }
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics or scrolling the page.
-    const_cast<Document&>(document).update_layout();
+    const_cast<Document&>(document).update_layout(UpdateLayoutReason::ElementSetScrollTop);
 
     // 9. If the element is the body element, document is in quirks mode, and the element is not potentially scrollable, invoke scroll() on window with scrollX as first argument and y as second argument, and terminate these steps.
     if (document.body() == this && document.in_quirks_mode() && !is_potentially_scrollable()) {
@@ -1659,7 +1659,7 @@ int Element::scroll_width() const
         return max(viewport_scroll_width, viewport_width);
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document).update_layout();
+    const_cast<Document&>(document).update_layout(UpdateLayoutReason::ElementScrollWidth);
 
     // 5. If the element is the body element, document is in quirks mode and the element is not potentially scrollable,
     //    return max(viewport scrolling area width, viewport width).
@@ -1698,7 +1698,7 @@ int Element::scroll_height() const
         return max(viewport_scroll_height, viewport_height);
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    const_cast<Document&>(document).update_layout();
+    const_cast<Document&>(document).update_layout(UpdateLayoutReason::ElementScrollHeight);
 
     // 5. If the element is the body element, document is in quirks mode and the element is not potentially scrollable,
     //    return max(viewport scrolling area height, viewport height).
@@ -2180,7 +2180,7 @@ ErrorOr<void> Element::scroll_into_view(Optional<Variant<bool, ScrollIntoViewOpt
     }
 
     // 7. If the element does not have any associated box, or is not available to user-agent features, then return.
-    document().update_layout();
+    document().update_layout(UpdateLayoutReason::ElementScrollIntoView);
     if (!layout_node())
         return Error::from_string_literal("Element has no associated box");
 
@@ -2761,7 +2761,7 @@ void Element::scroll(double x, double y)
         return;
 
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    document.update_layout();
+    document.update_layout(UpdateLayoutReason::ElementScroll);
 
     // 8. If the element is the root element invoke scroll() on window with scrollX on window as first argument and y as second argument, and terminate these steps.
     if (document.document_element() == this) {
@@ -2841,7 +2841,7 @@ void Element::scroll_by(HTML::ScrollToOptions options)
 bool Element::check_visibility(Optional<CheckVisibilityOptions> options)
 {
     // NOTE: Ensure that layout is up-to-date before looking at metrics.
-    document().update_layout();
+    document().update_layout(UpdateLayoutReason::ElementCheckVisibility);
 
     // 1. If this does not have an associated box, return false.
     if (!paintable_box())

Libraries/LibWeb/DOM/Node.cpp

@@ -2745,7 +2745,7 @@ ErrorOr<String> Node::name_or_description(NameOrDescription target, Document con
                 if (!child_node->is_element() && !child_node->is_text())
                     continue;
                 bool should_add_space = true;
-                const_cast<DOM::Document&>(document).update_layout();
+                const_cast<DOM::Document&>(document).update_layout(DOM::UpdateLayoutReason::NodeNameOrDescription);
                 auto const* layout_node = child_node->layout_node();
                 if (layout_node) {
                     auto display = layout_node->display();

Libraries/LibWeb/DOM/Range.cpp

@@ -1157,7 +1157,7 @@ GC::Ref<Geometry::DOMRectList> Range::get_client_rects()
     if (!start_container()->document().navigable())
         return Geometry::DOMRectList::create(realm(), {});
 
-    start_container()->document().update_layout();
+    start_container()->document().update_layout(DOM::UpdateLayoutReason::RangeGetClientRects);
     update_associated_selection();
     Vector<GC::Root<Geometry::DOMRect>> rects;
     // FIXME: take Range collapsed into consideration