Remove unnecessary branching from updateContextProvider (#13282)

This code had gotten unnecessarily complex after some recent changes.
Cleaned it up a bit.

packages/react-reconciler/src/ReactFiberBeginWork.js

@@ -73,6 +73,7 @@ import {
   propagateContextChange,
   readContext,
   prepareToReadContext,
+  calculateChangedBits,
 } from './ReactFiberNewContext';
 import {
   markActualRenderTimeStarted,
@@ -824,88 +825,34 @@ function updateContextProvider(current, workInProgress, renderExpirationTime) {
     // Initial render
     changedBits = MAX_SIGNED_31_BIT_INT;
   } else {
-    if (oldProps.value === newProps.value) {
+    const oldValue = oldProps.value;
+    changedBits = calculateChangedBits(context, newValue, oldValue);
+    if (changedBits === 0) {
       // No change. Bailout early if children are the same.
       if (
         oldProps.children === newProps.children &&
         !hasLegacyContextChanged()
       ) {
-        workInProgress.stateNode = 0;
-        pushProvider(workInProgress);
+        pushProvider(workInProgress, 0);
         return bailoutOnAlreadyFinishedWork(
           current,
           workInProgress,
           renderExpirationTime,
         );
       }
-      changedBits = 0;
     } else {
-      const oldValue = oldProps.value;
-      // Use Object.is to compare the new context value to the old value.
-      // Inlined Object.is polyfill.
-      // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is
-      if (
-        (oldValue === newValue &&
-          (oldValue !== 0 || 1 / oldValue === 1 / newValue)) ||
-        (oldValue !== oldValue && newValue !== newValue) // eslint-disable-line no-self-compare
-      ) {
-        // No change. Bailout early if children are the same.
-        if (
-          oldProps.children === newProps.children &&
-          !hasLegacyContextChanged()
-        ) {
-          workInProgress.stateNode = 0;
-          pushProvider(workInProgress);
-          return bailoutOnAlreadyFinishedWork(
-            current,
-            workInProgress,
-            renderExpirationTime,
-          );
-        }
-        changedBits = 0;
-      } else {
-        changedBits =
-          typeof context._calculateChangedBits === 'function'
-            ? context._calculateChangedBits(oldValue, newValue)
-            : MAX_SIGNED_31_BIT_INT;
-        if (__DEV__) {
-          warning(
-            (changedBits & MAX_SIGNED_31_BIT_INT) === changedBits,
-            'calculateChangedBits: Expected the return value to be a ' +
-              '31-bit integer. Instead received: %s',
-            changedBits,
-          );
-        }
-        changedBits |= 0;
-
-        if (changedBits === 0) {
-          // No change. Bailout early if children are the same.
-          if (
-            oldProps.children === newProps.children &&
-            !hasLegacyContextChanged()
-          ) {
-            workInProgress.stateNode = 0;
-            pushProvider(workInProgress);
-            return bailoutOnAlreadyFinishedWork(
-              current,
-              workInProgress,
-              renderExpirationTime,
-            );
-          }
-        } else {
-          propagateContextChange(
-            workInProgress,
-            context,
-            changedBits,
-            renderExpirationTime,
-          );
-        }
-      }
+      // The context value changed. Search for matching consumers and schedule
+      // them to update.
+      propagateContextChange(
+        workInProgress,
+        context,
+        changedBits,
+        renderExpirationTime,
+      );
     }
   }
 
-  workInProgress.stateNode = changedBits;
-  pushProvider(workInProgress);
+  pushProvider(workInProgress, changedBits);
 
   const newChildren = newProps.children;
   reconcileChildren(current, workInProgress, newChildren, renderExpirationTime);
@@ -1049,8 +996,7 @@ function beginWork(
         );
         break;
       case ContextProvider:
-        workInProgress.stateNode = 0;
-        pushProvider(workInProgress);
+        pushProvider(workInProgress, 0);
         break;
       case Profiler:
         if (enableProfilerTimer) {

packages/react-reconciler/src/ReactFiberNewContext.js

@@ -26,7 +26,9 @@ import {NoWork} from './ReactFiberExpirationTime';
 import {ContextProvider} from 'shared/ReactTypeOfWork';
 
 import invariant from 'shared/invariant';
+import warning from 'shared/warning';
 
+import MAX_SIGNED_31_BIT_INT from './maxSigned31BitInt';
 const valueCursor: StackCursor<mixed> = createCursor(null);
 const changedBitsCursor: StackCursor<number> = createCursor(0);
 
@@ -48,7 +50,7 @@ export function resetContextDependences(): void {
   lastContextWithAllBitsObserved = null;
 }
 
-export function pushProvider(providerFiber: Fiber): void {
+export function pushProvider(providerFiber: Fiber, changedBits: number): void {
   const context: ReactContext<any> = providerFiber.type._context;
 
   if (isPrimaryRenderer) {
@@ -56,7 +58,7 @@ export function pushProvider(providerFiber: Fiber): void {
     push(valueCursor, context._currentValue, providerFiber);
 
     context._currentValue = providerFiber.pendingProps.value;
-    context._changedBits = providerFiber.stateNode;
+    context._changedBits = changedBits;
     if (__DEV__) {
       warningWithoutStack(
         context._currentRenderer === undefined ||
@@ -72,7 +74,7 @@ export function pushProvider(providerFiber: Fiber): void {
     push(valueCursor, context._currentValue2, providerFiber);
 
     context._currentValue2 = providerFiber.pendingProps.value;
-    context._changedBits2 = providerFiber.stateNode;
+    context._changedBits2 = changedBits;
     if (__DEV__) {
       warningWithoutStack(
         context._currentRenderer2 === undefined ||
@@ -103,6 +105,39 @@ export function popProvider(providerFiber: Fiber): void {
   }
 }
 
+export function calculateChangedBits<T>(
+  context: ReactContext<T>,
+  newValue: T,
+  oldValue: T,
+) {
+  // Use Object.is to compare the new context value to the old value. Inlined
+  // Object.is polyfill.
+  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is
+  if (
+    (oldValue === newValue &&
+      (oldValue !== 0 || 1 / oldValue === 1 / (newValue: any))) ||
+    (oldValue !== oldValue && newValue !== newValue) // eslint-disable-line no-self-compare
+  ) {
+    // No change
+    return 0;
+  } else {
+    const changedBits =
+      typeof context._calculateChangedBits === 'function'
+        ? context._calculateChangedBits(oldValue, newValue)
+        : MAX_SIGNED_31_BIT_INT;
+
+    if (__DEV__) {
+      warning(
+        (changedBits & MAX_SIGNED_31_BIT_INT) === changedBits,
+        'calculateChangedBits: Expected the return value to be a ' +
+          '31-bit integer. Instead received: %s',
+        changedBits,
+      );
+    }
+    return changedBits | 0;
+  }
+}
+
 export function propagateContextChange(
   workInProgress: Fiber,
   context: ReactContext<mixed>,

packages/react/src/ReactContext.js

@@ -50,13 +50,12 @@ export function createContext<T>(
   const context: ReactContext<T> = {
     $$typeof: REACT_CONTEXT_TYPE,
     _calculateChangedBits: calculateChangedBits,
-    _defaultValue: defaultValue,
-    _currentValue: defaultValue,
     // As a workaround to support multiple concurrent renderers, we categorize
     // some renderers as primary and others as secondary. We only expect
     // there to be two concurrent renderers at most: React Native (primary) and
     // Fabric (secondary); React DOM (primary) and React ART (secondary).
     // Secondary renderers store their context values on separate fields.
+    _currentValue: defaultValue,
     _currentValue2: defaultValue,
     _changedBits: 0,
     _changedBits2: 0,

packages/shared/ReactTypes.js

@@ -82,7 +82,6 @@ export type ReactContext<T> = {
   unstable_read: () => T,
 
   _calculateChangedBits: ((a: T, b: T) => number) | null,
-  _defaultValue: T,
 
   _currentValue: T,
   _currentValue2: T,