Mark Paragraph as clean if it hasn't changed (#38749)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/38749

changelog: [internal]

# Request for comment

I'll gate this and extend this to TextInput if we think this is appropriate solution.

## Problem
Paragraph and TextInput have custom measure functions. They outsource measurements to the host platform. On Android, this means going through JNI (expensive).

When we architected YogaLayoutableShadowNode, we made intentional decision to dirty those nodes on every clone. This was to lower the complexity.

## Solution

One possible to solution is to just check if children, props or textAttributes have changed. If not, nothing has affected the layout and it is safe to mark the node as clean.

Reviewed By: NickGerleman

Differential Revision: D47914641

fbshipit-source-id: ab448fa18599eb2266984eba9f5d935caad1caed

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java

@@ -157,4 +157,7 @@ public class ReactFeatureFlags {
 
   /** Only swap left and right on Android in RTL scripts. */
   public static boolean doNotSwapLeftAndRightOnAndroidInLTR = false;
+
+  /** Clean yoga node when <Text /> does not change. */
+  public static boolean enableCleanParagraphYogaNode = false;
 }

packages/react-native/ReactAndroid/src/main/jni/react/fabric/Binding.cpp

@@ -433,6 +433,8 @@ void Binding::installFabricUIManager(
   CoreFeatures::enableMapBuffer = getFeatureFlagValue("useMapBufferProps");
   CoreFeatures::doNotSwapLeftAndRightOnAndroidInLTR =
       getFeatureFlagValue("doNotSwapLeftAndRightOnAndroidInLTR");
+  CoreFeatures::enableCleanParagraphYogaNode =
+      getFeatureFlagValue("enableCleanParagraphYogaNode");
 
   // RemoveDelete mega-op
   ShadowViewMutation::PlatformSupportsRemoveDeleteTreeInstruction =

packages/react-native/ReactCommon/react/renderer/components/text/ParagraphShadowNode.cpp

@@ -16,6 +16,7 @@
 #include <react/renderer/core/TraitCast.h>
 #include <react/renderer/graphics/rounding.h>
 #include <react/renderer/telemetry/TransactionTelemetry.h>
+#include <react/utils/CoreFeatures.h>
 
 #include "ParagraphState.h"
 
@@ -25,6 +26,20 @@ using Content = ParagraphShadowNode::Content;
 
 char const ParagraphComponentName[] = "Paragraph";
 
+ParagraphShadowNode::ParagraphShadowNode(
+    ShadowNode const &sourceShadowNode,
+    ShadowNodeFragment const &fragment)
+    : ConcreteViewShadowNode(sourceShadowNode, fragment) {
+  if (CoreFeatures::enableCleanParagraphYogaNode) {
+    if (!fragment.children && !fragment.props) {
+      // This ParagraphShadowNode was cloned but did not change
+      // in a way that affects its layout. Let's mark it clean
+      // to stop Yoga from traversing it.
+      cleanLayout();
+    }
+  }
+}
+
 Content const &ParagraphShadowNode::getContent(
     LayoutContext const &layoutContext) const {
   if (content_.has_value()) {

packages/react-native/ReactCommon/react/renderer/components/text/ParagraphShadowNode.h

@@ -34,6 +34,10 @@ class ParagraphShadowNode final : public ConcreteViewShadowNode<
  public:
   using ConcreteViewShadowNode::ConcreteViewShadowNode;
 
+  ParagraphShadowNode(
+      ShadowNode const &sourceShadowNode,
+      ShadowNodeFragment const &fragment);
+
   static ShadowNodeTraits BaseTraits() {
     auto traits = ConcreteViewShadowNode::BaseTraits();
     traits.set(ShadowNodeTraits::Trait::LeafYogaNode);

packages/react-native/ReactCommon/react/utils/CoreFeatures.cpp

@@ -18,5 +18,6 @@ bool CoreFeatures::cancelImageDownloadsOnRecycle = false;
 bool CoreFeatures::enableGranularScrollViewStateUpdatesIOS = false;
 bool CoreFeatures::enableMountHooks = false;
 bool CoreFeatures::doNotSwapLeftAndRightOnAndroidInLTR = false;
+bool CoreFeatures::enableCleanParagraphYogaNode = false;
 
 } // namespace facebook::react

packages/react-native/ReactCommon/react/utils/CoreFeatures.h

@@ -53,6 +53,9 @@ class CoreFeatures {
 
   // Only swap left and right on Android in RTL scripts.
   static bool doNotSwapLeftAndRightOnAndroidInLTR;
+
+  // Clean yoga node when <Text /> does not change.
+  static bool enableCleanParagraphYogaNode;
 };
 
 } // namespace facebook::react