[Invalidation Tracking] Trace StyleInvalidator setNeedsStyleRecalc

Source/core/css/invalidation/StyleInvalidator.cpp

Index: Source/core/css/invalidation/StyleInvalidator.cpp
diff --git a/Source/core/css/invalidation/StyleInvalidator.cpp b/Source/core/css/invalidation/StyleInvalidator.cpp
index 69f720f1171c5bf30d975cfd01b23abf6aea03f0..8d506a5a375a70a155f346b035b20d8b69c84dbb 100644
--- a/Source/core/css/invalidation/StyleInvalidator.cpp
+++ b/Source/core/css/invalidation/StyleInvalidator.cpp
@@ -13,10 +13,17 @@
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/ShadowRoot.h"
+#include "core/inspector/InspectorTraceEvents.h"
 #include "core/rendering/RenderObject.h"
 
 namespace blink {
 
+static const unsigned char* s_tracingEnabled = nullptr;
+
+#define TRACE_STYLE_INVALIDATOR_INVALIDATION_IF_ENABLED(element, reason) \
+    if (UNLIKELY(*s_tracingEnabled)) \
+        TRACE_STYLE_INVALIDATOR_INVALIDATION(element, reason);
+
 void StyleInvalidator::invalidate(Document& document)
 {
     RecursionData recursionData;
@@ -63,6 +70,8 @@ void StyleInvalidator::clearPendingInvalidations()
 
 StyleInvalidator::StyleInvalidator()
 {
+    s_tracingEnabled = TRACE_EVENT_API_GET_CATEGORY_ENABLED(TRACE_DISABLED_BY_DEFAULT("devtools.timeline.invalidationTracking"));
+    DescendantInvalidationSet::cacheTracingFlag();
 }
 
 StyleInvalidator::~StyleInvalidator()
@@ -82,12 +91,14 @@ void StyleInvalidator::RecursionData::pushInvalidationSet(const DescendantInvali
     m_invalidateCustomPseudo = invalidationSet.customPseudoInvalid();
 }
 
-bool StyleInvalidator::RecursionData::matchesCurrentInvalidationSets(Element& element)
+ALWAYS_INLINE bool StyleInvalidator::RecursionData::matchesCurrentInvalidationSets(Element& element)
 {
     ASSERT(!m_wholeSubtreeInvalid);
 
-    if (m_invalidateCustomPseudo && element.shadowPseudoId() != nullAtom)
+    if (m_invalidateCustomPseudo && element.shadowPseudoId() != nullAtom) {
+        TRACE_STYLE_INVALIDATOR_INVALIDATION_IF_ENABLED(element, InvalidateCustomPseudo);
         return true;
+    }
 
     for (const auto& invalidationSet : m_invalidationSets) {
         if (invalidationSet->invalidatesElement(element))
@@ -97,7 +108,7 @@ bool StyleInvalidator::RecursionData::matchesCurrentInvalidationSets(Element& el
     return false;
 }
 
-bool StyleInvalidator::checkInvalidationSetsAgainstElement(Element& element, StyleInvalidator::RecursionData& recursionData)
+ALWAYS_INLINE bool StyleInvalidator::checkInvalidationSetsAgainstElement(Element& element, StyleInvalidator::RecursionData& recursionData)
 {
     if (element.styleChangeType() >= SubtreeStyleChange || recursionData.wholeSubtreeInvalid()) {
         recursionData.setWholeSubtreeInvalid();
@@ -108,9 +119,15 @@ bool StyleInvalidator::checkInvalidationSetsAgainstElement(Element& element, Sty
             for (const auto& invalidationSet : *invalidationList)
                 recursionData.pushInvalidationSet(*invalidationSet);
             // FIXME: It's really only necessary to clone the render style for this element, not full style recalc.
+            if (UNLIKELY(*s_tracingEnabled)) {
+                TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline.invalidationTracking"),
+                    "StyleInvalidatorInvalidationTracking",
+                    "data", InspectorStyleInvalidatorInvalidateEvent::invalidationList(element, *invalidationList));
+            }
             return true;
         }
     }
+
     return recursionData.matchesCurrentInvalidationSets(element);
 }
 
@@ -148,10 +165,12 @@ bool StyleInvalidator::invalidate(Element& element, StyleInvalidator::RecursionD
         element.setNeedsStyleRecalc(recursionData.wholeSubtreeInvalid() ? SubtreeStyleChange : LocalStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleInvalidator));
     } else if (recursionData.hasInvalidationSets() && someChildrenNeedStyleRecalc) {
         // Clone the RenderStyle in order to preserve correct style sharing, if possible. Otherwise recalc style.
-        if (RenderObject* renderer = element.renderer())
+        if (RenderObject* renderer = element.renderer()) {
             renderer->setStyleInternal(RenderStyle::clone(renderer->style()));
-        else
+        } else {
+            TRACE_STYLE_INVALIDATOR_INVALIDATION_IF_ENABLED(element, PreventStyleSharingForParent);
             element.setNeedsStyleRecalc(LocalStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::StyleInvalidator));
+        }
     }
 
     element.clearChildNeedsStyleInvalidation();