Add early return to diffProperties (#28842)

## Summary

This PR adds early return to the `diff` function. We don't need to go
through all the entries of `nextProps`, process and deep-diff the values
if `nextProps` is the same object as `prevProps`. Roughly 6% of all
`diffProperties` calls can be skipped.

## How did you test this change?

RNTester.

packages/react-native-renderer/src/ReactNativeAttributePayload.js

@@ -14,6 +14,8 @@ import {
 } from 'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
 import isArray from 'shared/isArray';
 
+import {enableEarlyReturnForPropDiffing} from 'shared/ReactFeatureFlags';
+
 import type {AttributeConfiguration} from './ReactNativeTypes';
 
 const emptyObject = {};
@@ -483,6 +485,11 @@ export function diff(
   nextProps: Object,
   validAttributes: AttributeConfiguration,
 ): null | Object {
+  if (enableEarlyReturnForPropDiffing) {
+    if (prevProps === nextProps) {
+      return null; // no change
+    }
+  }
   return diffProperties(
     null, // updatePayload
     prevProps,

packages/shared/ReactFeatureFlags.js

@@ -119,6 +119,8 @@ export const passChildrenWhenCloningPersistedNodes = false;
 
 export const enableServerComponentLogs = __EXPERIMENTAL__;
 
+export const enableEarlyReturnForPropDiffing = false;
+
 /**
  * Enables an expiration time for retry lanes to avoid starvation.
  */

packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js

@@ -20,6 +20,7 @@
 export const alwaysThrottleRetries = __VARIANT__;
 export const consoleManagedByDevToolsDuringStrictMode = __VARIANT__;
 export const enableAsyncActions = __VARIANT__;
+export const enableEarlyReturnForPropDiffing = __VARIANT__;
 export const enableComponentStackLocations = __VARIANT__;
 export const enableDeferRootSchedulingToMicrotask = __VARIANT__;
 export const enableInfiniteRenderLoopDetection = __VARIANT__;

packages/shared/forks/ReactFeatureFlags.native-fb.js

@@ -22,6 +22,7 @@ export const {
   alwaysThrottleRetries,
   consoleManagedByDevToolsDuringStrictMode,
   enableAsyncActions,
+  enableEarlyReturnForPropDiffing,
   enableComponentStackLocations,
   enableDeferRootSchedulingToMicrotask,
   enableInfiniteRenderLoopDetection,

packages/shared/forks/ReactFeatureFlags.native-oss.js

@@ -101,6 +101,7 @@ export const allowConcurrentByDefault = false;
 export const enableTransitionTracing = false;
 export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
 export const passChildrenWhenCloningPersistedNodes = false;
+export const enableEarlyReturnForPropDiffing = false;
 
 // Profiling Only
 export const enableProfilerTimer = __PROFILE__;

packages/shared/forks/ReactFeatureFlags.test-renderer.js

@@ -76,6 +76,7 @@ export const disableClientCache = true;
 export const enableServerComponentKeys = true;
 export const enableServerComponentLogs = true;
 export const enableInfiniteRenderLoopDetection = false;
+export const enableEarlyReturnForPropDiffing = false;
 
 // TODO: This must be in sync with the main ReactFeatureFlags file because
 // the Test Renderer's value must be the same as the one used by the

packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js

@@ -87,6 +87,7 @@ export const disableLegacyMode = false;
 export const disableDOMTestUtils = false;
 
 export const disableDefaultPropsExceptForClasses = false;
+export const enableEarlyReturnForPropDiffing = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.test-renderer.www.js

@@ -87,6 +87,7 @@ export const disableLegacyMode = false;
 export const disableDOMTestUtils = false;
 
 export const disableDefaultPropsExceptForClasses = false;
+export const enableEarlyReturnForPropDiffing = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.www.js

@@ -117,6 +117,7 @@ export const disableStringRefs = false;
 export const disableLegacyMode = __EXPERIMENTAL__;
 
 export const disableDOMTestUtils = false;
+export const enableEarlyReturnForPropDiffing = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);