Remove enableDifferentiatorMutationVectorPreallocation feature flag (#57224)

Summary:
Pull Request resolved: #57224

The `enableDifferentiatorMutationVectorPreallocation` flag gated a mutation-vector pre-allocation optimization in the `Differentiator`. It was never ramped and is being removed. The flag defaulted to `false`, so this restores the pre-flag behavior by deleting the gated `reserve(...)` calls (an allocation hint with no effect on diffing results) and keeping the default `mutations.reserve(256)`.

Removes the flag definition from `ReactNativeFeatureFlags.config.js`, the gated call sites in `Differentiator.cpp`, and the regenerated feature-flag files (via `yarn featureflags --update`).

Changelog: [Internal]

Reviewed By: javache

Differential Revision: D108411519

fbshipit-source-id: 73844c54627545a111ad2bd83fa09171d87c3396

Author: sammy-SC

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<7e91da9df64ce42424101d7d72356c4a>>
+ * @generated SignedSource<<5307fff9429956a3f3f2f54f2b6b00e7>>
  */
 
 /**
@@ -132,12 +132,6 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun enableDestroyShadowTreeRevisionAsync(): Boolean = accessor.enableDestroyShadowTreeRevisionAsync()
 
-  /**
-   * Pre-allocate mutation vectors in the Differentiator to reduce reallocation overhead during shadow view diffing.
-   */
-  @JvmStatic
-  public fun enableDifferentiatorMutationVectorPreallocation(): Boolean = accessor.enableDifferentiatorMutationVectorPreallocation()
-
   /**
    * When enabled a subset of components will avoid double measurement on Android.
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<3c0e10dee93b76f3e66ca79d26f2b4f2>>
+ * @generated SignedSource<<d179182254004aa1f5adf671eccb953f>>
  */
 
 /**
@@ -37,7 +37,6 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var enableCppPropsIteratorSetterCache: Boolean? = null
   private var enableCustomFocusSearchOnClippedElementsAndroidCache: Boolean? = null
   private var enableDestroyShadowTreeRevisionAsyncCache: Boolean? = null
-  private var enableDifferentiatorMutationVectorPreallocationCache: Boolean? = null
   private var enableDoubleMeasurementFixAndroidCache: Boolean? = null
   private var enableEagerRootViewAttachmentCache: Boolean? = null
   private var enableExclusivePropsUpdateAndroidCache: Boolean? = null
@@ -262,15 +261,6 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
-  override fun enableDifferentiatorMutationVectorPreallocation(): Boolean {
-    var cached = enableDifferentiatorMutationVectorPreallocationCache
-    if (cached == null) {
-      cached = ReactNativeFeatureFlagsCxxInterop.enableDifferentiatorMutationVectorPreallocation()
-      enableDifferentiatorMutationVectorPreallocationCache = cached
-    }
-    return cached
-  }
-
   override fun enableDoubleMeasurementFixAndroid(): Boolean {
     var cached = enableDoubleMeasurementFixAndroidCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<e9cc7d01ac1884710f131fbf375f3502>>
+ * @generated SignedSource<<6dc403c11108a657d48ec9573bee842f>>
  */
 
 /**
@@ -62,8 +62,6 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun enableDestroyShadowTreeRevisionAsync(): Boolean
 
-  @DoNotStrip @JvmStatic public external fun enableDifferentiatorMutationVectorPreallocation(): Boolean
-
   @DoNotStrip @JvmStatic public external fun enableDoubleMeasurementFixAndroid(): Boolean
 
   @DoNotStrip @JvmStatic public external fun enableEagerRootViewAttachment(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<ad505c0c71fa0c6e665a218606b596da>>
+ * @generated SignedSource<<452edce222866440ff3794deb178a7f4>>
  */
 
 /**
@@ -57,8 +57,6 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun enableDestroyShadowTreeRevisionAsync(): Boolean = false
 
-  override fun enableDifferentiatorMutationVectorPreallocation(): Boolean = false
-
   override fun enableDoubleMeasurementFixAndroid(): Boolean = false
 
   override fun enableEagerRootViewAttachment(): Boolean = false

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<fa85d53197cbdce6b1373fbadf3cf2b9>>
+ * @generated SignedSource<<8ba7f19e8afe329937b1b36d3b83dbc5>>
  */
 
 /**
@@ -41,7 +41,6 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var enableCppPropsIteratorSetterCache: Boolean? = null
   private var enableCustomFocusSearchOnClippedElementsAndroidCache: Boolean? = null
   private var enableDestroyShadowTreeRevisionAsyncCache: Boolean? = null
-  private var enableDifferentiatorMutationVectorPreallocationCache: Boolean? = null
   private var enableDoubleMeasurementFixAndroidCache: Boolean? = null
   private var enableEagerRootViewAttachmentCache: Boolean? = null
   private var enableExclusivePropsUpdateAndroidCache: Boolean? = null
@@ -283,16 +282,6 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
-  override fun enableDifferentiatorMutationVectorPreallocation(): Boolean {
-    var cached = enableDifferentiatorMutationVectorPreallocationCache
-    if (cached == null) {
-      cached = currentProvider.enableDifferentiatorMutationVectorPreallocation()
-      accessedFeatureFlags.add("enableDifferentiatorMutationVectorPreallocation")
-      enableDifferentiatorMutationVectorPreallocationCache = cached
-    }
-    return cached
-  }
-
   override fun enableDoubleMeasurementFixAndroid(): Boolean {
     var cached = enableDoubleMeasurementFixAndroidCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<a460b28871fc3f928dcc2d1a3bf66422>>
+ * @generated SignedSource<<3a3f9014f644b6b964b50d0974a7b9b5>>
  */
 
 /**
@@ -57,8 +57,6 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun enableDestroyShadowTreeRevisionAsync(): Boolean
 
-  @DoNotStrip public fun enableDifferentiatorMutationVectorPreallocation(): Boolean
-
   @DoNotStrip public fun enableDoubleMeasurementFixAndroid(): Boolean
 
   @DoNotStrip public fun enableEagerRootViewAttachment(): Boolean

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<ea8284ad906ae89281a3fbd849e88c19>>
+ * @generated SignedSource<<70e4f4b4bb3aa28a644ede80ceeb4fc3>>
  */
 
 /**
@@ -141,12 +141,6 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
-  bool enableDifferentiatorMutationVectorPreallocation() override {
-    static const auto method =
-        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableDifferentiatorMutationVectorPreallocation");
-    return method(javaProvider_);
-  }
-
   bool enableDoubleMeasurementFixAndroid() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("enableDoubleMeasurementFixAndroid");
@@ -656,11 +650,6 @@ bool JReactNativeFeatureFlagsCxxInterop::enableDestroyShadowTreeRevisionAsync(
   return ReactNativeFeatureFlags::enableDestroyShadowTreeRevisionAsync();
 }
 
-bool JReactNativeFeatureFlagsCxxInterop::enableDifferentiatorMutationVectorPreallocation(
-    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
-  return ReactNativeFeatureFlags::enableDifferentiatorMutationVectorPreallocation();
-}
-
 bool JReactNativeFeatureFlagsCxxInterop::enableDoubleMeasurementFixAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::enableDoubleMeasurementFixAndroid();
@@ -1093,9 +1082,6 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "enableDestroyShadowTreeRevisionAsync",
         JReactNativeFeatureFlagsCxxInterop::enableDestroyShadowTreeRevisionAsync),
-      makeNativeMethod(
-        "enableDifferentiatorMutationVectorPreallocation",
-        JReactNativeFeatureFlagsCxxInterop::enableDifferentiatorMutationVectorPreallocation),
       makeNativeMethod(
         "enableDoubleMeasurementFixAndroid",
         JReactNativeFeatureFlagsCxxInterop::enableDoubleMeasurementFixAndroid),

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<746da63dcbec1bb165731e7380993659>>
+ * @generated SignedSource<<19ab9f9ec4e3470290f69e0803ade5d4>>
  */
 
 /**
@@ -81,9 +81,6 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool enableDestroyShadowTreeRevisionAsync(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
-  static bool enableDifferentiatorMutationVectorPreallocation(
-    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
-
   static bool enableDoubleMeasurementFixAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<38e26847bb30888adaf6a965dae07cfb>>
+ * @generated SignedSource<<de5333acce3cebc8c1f88e7d95b111e8>>
  */
 
 /**
@@ -94,10 +94,6 @@ bool ReactNativeFeatureFlags::enableDestroyShadowTreeRevisionAsync() {
   return getAccessor().enableDestroyShadowTreeRevisionAsync();
 }
 
-bool ReactNativeFeatureFlags::enableDifferentiatorMutationVectorPreallocation() {
-  return getAccessor().enableDifferentiatorMutationVectorPreallocation();
-}
-
 bool ReactNativeFeatureFlags::enableDoubleMeasurementFixAndroid() {
   return getAccessor().enableDoubleMeasurementFixAndroid();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<6958847f0d788c06cf64478ee2c36386>>
+ * @generated SignedSource<<9180537aa2031cfcbab5ffbdf1dc32d1>>
  */
 
 /**
@@ -124,11 +124,6 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool enableDestroyShadowTreeRevisionAsync();
 
-  /**
-   * Pre-allocate mutation vectors in the Differentiator to reduce reallocation overhead during shadow view diffing.
-   */
-  RN_EXPORT static bool enableDifferentiatorMutationVectorPreallocation();
-
   /**
    * When enabled a subset of components will avoid double measurement on Android.
    */