[compiler] More readable alias signature declarations

Now that we have support for defining aliasing signatures in moduleTypeProvider, which uses string names for receiver/args/returns/etc, we can reuse that same form for builtin declarations. The declarations are written in the unparsed form and than parsed/validated when registered (in the addFunction/addHook call).

This also required flushing out configs/schemas for more effect types.

compiler/packages/babel-plugin-react-compiler/src/HIR/Globals.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {Effect, makeIdentifierId, ValueKind, ValueReason} from './HIR';
+import {Effect, ValueKind, ValueReason} from './HIR';
 import {
   BUILTIN_SHAPES,
   BuiltInArrayId,
@@ -34,7 +34,6 @@ import {
   addFunction,
   addHook,
   addObject,
-  signatureArgument,
 } from './ObjectShape';
 import {BuiltInType, ObjectType, PolyType} from './Types';
 import {TypeConfig} from './TypeSchema';
@@ -646,35 +645,35 @@ const REACT_APIS: Array<[string, BuiltInType]> = [
         hookKind: 'useEffect',
         returnValueKind: ValueKind.Frozen,
         aliasing: {
-          receiver: makeIdentifierId(0),
+          receiver: '@receiver',
           params: [],
-          rest: makeIdentifierId(1),
-          returns: makeIdentifierId(2),
-          temporaries: [signatureArgument(3)],
+          rest: '@rest',
+          returns: '@returns',
+          temporaries: ['@effect'],
           effects: [
             // Freezes the function and deps
             {
               kind: 'Freeze',
-              value: signatureArgument(1),
+              value: '@rest',
               reason: ValueReason.Effect,
             },
             // Internally creates an effect object that captures the function and deps
             {
               kind: 'Create',
-              into: signatureArgument(3),
+              into: '@effect',
               value: ValueKind.Frozen,
               reason: ValueReason.KnownReturnSignature,
             },
             // The effect stores the function and dependencies
             {
               kind: 'Capture',
-              from: signatureArgument(1),
-              into: signatureArgument(3),
+              from: '@rest',
+              into: '@effect',
             },
             // Returns undefined
             {
               kind: 'Create',
-              into: signatureArgument(2),
+              into: '@returns',
               value: ValueKind.Primitive,
               reason: ValueReason.KnownReturnSignature,
             },
@@ -906,6 +905,7 @@ export function installTypeConfig(
         noAlias: typeConfig.noAlias === true,
         mutableOnlyIfOperandsAreMutable:
           typeConfig.mutableOnlyIfOperandsAreMutable === true,
+        aliasing: typeConfig.aliasing,
       });
     }
     case 'hook': {
@@ -923,6 +923,7 @@ export function installTypeConfig(
         ),
         returnValueKind: typeConfig.returnValueKind ?? ValueKind.Frozen,
         noAlias: typeConfig.noAlias === true,
+        aliasing: typeConfig.aliasing,
       });
     }
     case 'object': {

compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts

@@ -1453,6 +1453,20 @@ export const ValueKindSchema = z.enum([
   ValueKind.Context,
 ]);
 
+export const ValueReasonSchema = z.enum([
+  ValueReason.Context,
+  ValueReason.Effect,
+  ValueReason.Global,
+  ValueReason.HookCaptured,
+  ValueReason.HookReturn,
+  ValueReason.JsxCaptured,
+  ValueReason.KnownReturnSignature,
+  ValueReason.Other,
+  ValueReason.ReactiveFunctionArgument,
+  ValueReason.ReducerState,
+  ValueReason.State,
+]);
+
 // The effect with which a value is modified.
 export enum Effect {
   // Default value: not allowed after lifetime inference

compiler/packages/babel-plugin-react-compiler/src/HIR/ObjectShape.ts

@@ -6,14 +6,18 @@
  */
 
 import {CompilerError} from '../CompilerError';
-import {AliasingSignature} from '../Inference/AliasingEffects';
+import {AliasingEffect, AliasingSignature} from '../Inference/AliasingEffects';
+import {assertExhaustive} from '../Utils/utils';
 import {
   Effect,
   GeneratedSource,
+  Hole,
   makeDeclarationId,
   makeIdentifierId,
   makeInstructionId,
   Place,
+  SourceLocation,
+  SpreadPattern,
   ValueKind,
   ValueReason,
 } from './HIR';
@@ -25,6 +29,7 @@ import {
   PolyType,
   PrimitiveType,
 } from './Types';
+import {AliasingEffectConfig, AliasingSignatureConfig} from './TypeSchema';
 
 /*
  * This file exports types and defaults for JavaScript object shapes. These are
@@ -53,13 +58,20 @@ function createAnonId(): string {
 export function addFunction(
   registry: ShapeRegistry,
   properties: Iterable<[string, BuiltInType | PolyType]>,
-  fn: Omit<FunctionSignature, 'hookKind'>,
+  fn: Omit<FunctionSignature, 'hookKind' | 'aliasing'> & {
+    aliasing?: AliasingSignatureConfig | null | undefined;
+  },
   id: string | null = null,
   isConstructor: boolean = false,
 ): FunctionType {
   const shapeId = id ?? createAnonId();
+  const aliasing =
+    fn.aliasing != null
+      ? parseAliasingSignatureConfig(fn.aliasing, '<builtin>', GeneratedSource)
+      : null;
   addShape(registry, shapeId, properties, {
     ...fn,
+    aliasing,
     hookKind: null,
   });
   return {
@@ -77,11 +89,18 @@ export function addFunction(
  */
 export function addHook(
   registry: ShapeRegistry,
-  fn: FunctionSignature & {hookKind: HookKind},
+  fn: Omit<FunctionSignature, 'aliasing'> & {
+    hookKind: HookKind;
+    aliasing?: AliasingSignatureConfig | null | undefined;
+  },
   id: string | null = null,
 ): FunctionType {
   const shapeId = id ?? createAnonId();
-  addShape(registry, shapeId, [], fn);
+  const aliasing =
+    fn.aliasing != null
+      ? parseAliasingSignatureConfig(fn.aliasing, '<builtin>', GeneratedSource)
+      : null;
+  addShape(registry, shapeId, [], {...fn, aliasing});
   return {
     kind: 'Function',
     return: fn.returnType,
@@ -90,6 +109,129 @@ export function addHook(
   };
 }
 
+function parseAliasingSignatureConfig(
+  typeConfig: AliasingSignatureConfig,
+  moduleName: string,
+  loc: SourceLocation,
+): AliasingSignature {
+  const lifetimes = new Map<string, Place>();
+  function define(temp: string): Place {
+    CompilerError.invariant(!lifetimes.has(temp), {
+      reason: `Invalid type configuration for module`,
+      description: `Expected aliasing signature to have unique names for receiver, params, rest, returns, and temporaries in module '${moduleName}'`,
+      loc,
+    });
+    const place = signatureArgument(lifetimes.size);
+    lifetimes.set(temp, place);
+    return place;
+  }
+  function lookup(temp: string): Place {
+    const place = lifetimes.get(temp);
+    CompilerError.invariant(place != null, {
+      reason: `Invalid type configuration for module`,
+      description: `Expected aliasing signature effects to reference known names from receiver/params/rest/returns/temporaries, but '${temp}' is not a known name in '${moduleName}'`,
+      loc,
+    });
+    return place;
+  }
+  const receiver = define(typeConfig.receiver);
+  const params = typeConfig.params.map(define);
+  const rest = typeConfig.rest != null ? define(typeConfig.rest) : null;
+  const returns = define(typeConfig.returns);
+  const temporaries = typeConfig.temporaries.map(define);
+  const effects = typeConfig.effects.map(
+    (effect: AliasingEffectConfig): AliasingEffect => {
+      switch (effect.kind) {
+        case 'CreateFrom':
+        case 'Capture':
+        case 'Alias':
+        case 'Assign': {
+          const from = lookup(effect.from);
+          const into = lookup(effect.into);
+          return {
+            kind: effect.kind,
+            from,
+            into,
+          };
+        }
+        case 'Mutate':
+        case 'MutateTransitiveConditionally': {
+          const value = lookup(effect.value);
+          return {kind: effect.kind, value};
+        }
+        case 'Create': {
+          const into = lookup(effect.into);
+          return {
+            kind: 'Create',
+            into,
+            reason: effect.reason,
+            value: effect.value,
+          };
+        }
+        case 'Freeze': {
+          const value = lookup(effect.value);
+          return {
+            kind: 'Freeze',
+            value,
+            reason: effect.reason,
+          };
+        }
+        case 'Impure': {
+          const place = lookup(effect.place);
+          return {
+            kind: 'Impure',
+            place,
+            error: CompilerError.throwTodo({
+              reason: 'Support impure effect declarations',
+              loc: GeneratedSource,
+            }),
+          };
+        }
+        case 'Apply': {
+          const receiver = lookup(effect.receiver);
+          const fn = lookup(effect.function);
+          const args: Array<Place | SpreadPattern | Hole> = effect.args.map(
+            arg => {
+              if (typeof arg === 'string') {
+                return lookup(arg);
+              } else if (arg.kind === 'Spread') {
+                return {kind: 'Spread', place: lookup(arg.place)};
+              } else {
+                return arg;
+              }
+            },
+          );
+          const into = lookup(effect.into);
+          return {
+            kind: 'Apply',
+            receiver,
+            function: fn,
+            mutatesFunction: effect.mutatesFunction,
+            args,
+            into,
+            loc,
+            signature: null,
+          };
+        }
+        default: {
+          assertExhaustive(
+            effect,
+            `Unexpected effect kind '${(effect as any).kind}'`,
+          );
+        }
+      }
+    },
+  );
+  return {
+    receiver: receiver.identifier.id,
+    params: params.map(p => p.identifier.id),
+    rest: rest != null ? rest.identifier.id : null,
+    returns: returns.identifier.id,
+    temporaries,
+    effects,
+  };
+}
+
 /*
  * Add an object to an existing ShapeRegistry.
  *
@@ -192,8 +334,7 @@ export type FunctionSignature = {
 
   canonicalName?: string;
 
-  aliasing?: AliasingSignature | null;
-  todo_aliasing?: AliasingSignature | null;
+  aliasing?: AliasingSignature | null | undefined;
 };
 
 /*
@@ -320,24 +461,24 @@ addObject(BUILTIN_SHAPES, BuiltInArrayId, [
       calleeEffect: Effect.Store,
       returnValueKind: ValueKind.Primitive,
       aliasing: {
-        receiver: makeIdentifierId(0),
+        receiver: '@receiver',
         params: [],
-        rest: makeIdentifierId(1),
-        returns: makeIdentifierId(2),
+        rest: '@rest',
+        returns: '@returns',
         temporaries: [],
         effects: [
           // Push directly mutates the array itself
-          {kind: 'Mutate', value: signatureArgument(0)},
+          {kind: 'Mutate', value: '@receiver'},
           // The arguments are captured into the array
           {
             kind: 'Capture',
-            from: signatureArgument(1),
-            into: signatureArgument(0),
+            from: '@rest',
+            into: '@receiver',
           },
           // Returns the new length, a primitive
           {
             kind: 'Create',
-            into: signatureArgument(2),
+            into: '@returns',
             value: ValueKind.Primitive,
             reason: ValueReason.KnownReturnSignature,
           },
@@ -374,58 +515,56 @@ addObject(BUILTIN_SHAPES, BuiltInArrayId, [
       noAlias: true,
       mutableOnlyIfOperandsAreMutable: true,
       aliasing: {
-        receiver: makeIdentifierId(0),
-        params: [makeIdentifierId(1)],
+        receiver: '@receiver',
+        params: ['@callback'],
         rest: null,
-        returns: makeIdentifierId(2),
+        returns: '@returns',
         temporaries: [
           // Temporary representing captured items of the receiver
-          signatureArgument(3),
+          '@item',
           // Temporary representing the result of the callback
-          signatureArgument(4),
+          '@callbackReturn',
           /*
            * Undefined `this` arg to the callback. Note the signature does not
            * support passing an explicit thisArg second param
            */
-          signatureArgument(5),
+          '@thisArg',
         ],
         effects: [
           // Map creates a new mutable array
           {
             kind: 'Create',
-            into: signatureArgument(2),
+            into: '@returns',
             value: ValueKind.Mutable,
             reason: ValueReason.KnownReturnSignature,
           },
           // The first arg to the callback is an item extracted from the receiver array
           {
             kind: 'CreateFrom',
-            from: signatureArgument(0),
-            into: signatureArgument(3),
+            from: '@receiver',
+            into: '@item',
           },
           // The undefined this for the callback
           {
             kind: 'Create',
-            into: signatureArgument(5),
+            into: '@thisArg',
             value: ValueKind.Primitive,
             reason: ValueReason.KnownReturnSignature,
           },
           // calls the callback, returning the result into a temporary
           {
             kind: 'Apply',
-            receiver: signatureArgument(5),
-            args: [signatureArgument(3), {kind: 'Hole'}, signatureArgument(0)],
-            function: signatureArgument(1),
-            into: signatureArgument(4),
-            signature: null,
+            receiver: '@thisArg',
+            args: ['@item', {kind: 'Hole'}, '@receiver'],
+            function: '@callback',
+            into: '@callbackReturn',
             mutatesFunction: false,
-            loc: GeneratedSource,
           },
           // captures the result of the callback into the return array
           {
             kind: 'Capture',
-            from: signatureArgument(4),
-            into: signatureArgument(2),
+            from: '@callbackReturn',
+            into: '@returns',
           },
         ],
       },
@@ -577,28 +716,28 @@ addObject(BUILTIN_SHAPES, BuiltInSetId, [
       // returnValueKind is technically dependent on the ValueKind of the set itself
       returnValueKind: ValueKind.Mutable,
       aliasing: {
-        receiver: makeIdentifierId(0),
+        receiver: '@receiver',
         params: [],
-        rest: makeIdentifierId(1),
-        returns: makeIdentifierId(2),
+        rest: '@rest',
+        returns: '@returns',
         temporaries: [],
         effects: [
           // Set.add returns the receiver Set
           {
             kind: 'Assign',
-            from: signatureArgument(0),
-            into: signatureArgument(2),
+            from: '@receiver',
+            into: '@returns',
           },
           // Set.add mutates the set itself
           {
             kind: 'Mutate',
-            value: signatureArgument(0),
+            value: '@receiver',
           },
           // Captures the rest params into the set
           {
             kind: 'Capture',
-            from: signatureArgument(1),
-            into: signatureArgument(0),
+            from: '@rest',
+            into: '@receiver',
           },
         ],
       },
@@ -1303,30 +1442,30 @@ export const DefaultNonmutatingHook = addHook(
     hookKind: 'Custom',
     returnValueKind: ValueKind.Frozen,
     aliasing: {
-      receiver: makeIdentifierId(0),
+      receiver: '@receiver',
       params: [],
-      rest: makeIdentifierId(1),
-      returns: makeIdentifierId(2),
+      rest: '@rest',
+      returns: '@returns',
       temporaries: [],
       effects: [
         // Freeze the arguments
         {
           kind: 'Freeze',
-          value: signatureArgument(1),
+          value: '@rest',
           reason: ValueReason.HookCaptured,
         },
         // Returns a frozen value
         {
           kind: 'Create',
-          into: signatureArgument(2),
+          into: '@returns',
           value: ValueKind.Frozen,
           reason: ValueReason.HookReturn,
         },
         // May alias any arguments into the return
         {
           kind: 'Alias',
-          from: signatureArgument(1),
-          into: signatureArgument(2),
+          from: '@rest',
+          into: '@returns',
         },
       ],
     },

compiler/packages/babel-plugin-react-compiler/src/HIR/TypeSchema.ts

@@ -8,7 +8,12 @@
 import {isValidIdentifier} from '@babel/types';
 import {z} from 'zod';
 import {Effect, ValueKind} from '..';
-import {EffectSchema, ValueKindSchema} from './HIR';
+import {
+  EffectSchema,
+  ValueKindSchema,
+  ValueReason,
+  ValueReasonSchema,
+} from './HIR';
 
 export type ObjectPropertiesConfig = {[key: string]: TypeConfig};
 export const ObjectPropertiesSchema: z.ZodType<ObjectPropertiesConfig> = z
@@ -31,6 +36,194 @@ export const ObjectTypeSchema: z.ZodType<ObjectTypeConfig> = z.object({
   properties: ObjectPropertiesSchema.nullable(),
 });
 
+export const LifetimeIdSchema = z.string().refine(id => id.startsWith('@'), {
+  message: "Placeholder names must start with '@'",
+});
+
+export type FreezeEffectConfig = {
+  kind: 'Freeze';
+  value: string;
+  reason: ValueReason;
+};
+
+export const FreezeEffectSchema: z.ZodType<FreezeEffectConfig> = z.object({
+  kind: z.literal('Freeze'),
+  value: LifetimeIdSchema,
+  reason: ValueReasonSchema,
+});
+
+export type MutateEffectConfig = {
+  kind: 'Mutate';
+  value: string;
+};
+
+export const MutateEffectSchema: z.ZodType<MutateEffectConfig> = z.object({
+  kind: z.literal('Mutate'),
+  value: LifetimeIdSchema,
+});
+
+export type MutateTransitiveConditionallyConfig = {
+  kind: 'MutateTransitiveConditionally';
+  value: string;
+};
+
+export const MutateTransitiveConditionallySchema: z.ZodType<MutateTransitiveConditionallyConfig> =
+  z.object({
+    kind: z.literal('MutateTransitiveConditionally'),
+    value: LifetimeIdSchema,
+  });
+
+export type CreateEffectConfig = {
+  kind: 'Create';
+  into: string;
+  value: ValueKind;
+  reason: ValueReason;
+};
+
+export const CreateEffectSchema: z.ZodType<CreateEffectConfig> = z.object({
+  kind: z.literal('Create'),
+  into: LifetimeIdSchema,
+  value: ValueKindSchema,
+  reason: ValueReasonSchema,
+});
+
+export type AssignEffectConfig = {
+  kind: 'Assign';
+  from: string;
+  into: string;
+};
+
+export const AssignEffectSchema: z.ZodType<AssignEffectConfig> = z.object({
+  kind: z.literal('Assign'),
+  from: LifetimeIdSchema,
+  into: LifetimeIdSchema,
+});
+
+export type AliasEffectConfig = {
+  kind: 'Alias';
+  from: string;
+  into: string;
+};
+
+export const AliasEffectSchema: z.ZodType<AliasEffectConfig> = z.object({
+  kind: z.literal('Alias'),
+  from: LifetimeIdSchema,
+  into: LifetimeIdSchema,
+});
+
+export type CaptureEffectConfig = {
+  kind: 'Capture';
+  from: string;
+  into: string;
+};
+
+export const CaptureEffectSchema: z.ZodType<CaptureEffectConfig> = z.object({
+  kind: z.literal('Capture'),
+  from: LifetimeIdSchema,
+  into: LifetimeIdSchema,
+});
+
+export type CreateFromEffectConfig = {
+  kind: 'CreateFrom';
+  from: string;
+  into: string;
+};
+
+export const CreateFromEffectSchema: z.ZodType<CreateFromEffectConfig> =
+  z.object({
+    kind: z.literal('CreateFrom'),
+    from: LifetimeIdSchema,
+    into: LifetimeIdSchema,
+  });
+
+export type ApplyArgConfig =
+  | string
+  | {kind: 'Spread'; place: string}
+  | {kind: 'Hole'};
+
+export const ApplyArgSchema: z.ZodType<ApplyArgConfig> = z.union([
+  LifetimeIdSchema,
+  z.object({
+    kind: z.literal('Spread'),
+    place: LifetimeIdSchema,
+  }),
+  z.object({
+    kind: z.literal('Hole'),
+  }),
+]);
+
+export type ApplyEffectConfig = {
+  kind: 'Apply';
+  receiver: string;
+  function: string;
+  mutatesFunction: boolean;
+  args: Array<ApplyArgConfig>;
+  into: string;
+};
+
+export const ApplyEffectSchema: z.ZodType<ApplyEffectConfig> = z.object({
+  kind: z.literal('Apply'),
+  receiver: LifetimeIdSchema,
+  function: LifetimeIdSchema,
+  mutatesFunction: z.boolean(),
+  args: z.array(ApplyArgSchema),
+  into: LifetimeIdSchema,
+});
+
+export type ImpureEffectConfig = {
+  kind: 'Impure';
+  place: string;
+};
+
+export const ImpureEffectSchema: z.ZodType<ImpureEffectConfig> = z.object({
+  kind: z.literal('Impure'),
+  place: LifetimeIdSchema,
+});
+
+export type AliasingEffectConfig =
+  | FreezeEffectConfig
+  | CreateEffectConfig
+  | CreateFromEffectConfig
+  | AssignEffectConfig
+  | AliasEffectConfig
+  | CaptureEffectConfig
+  | ImpureEffectConfig
+  | MutateEffectConfig
+  | MutateTransitiveConditionallyConfig
+  | ApplyEffectConfig;
+
+export const AliasingEffectSchema: z.ZodType<AliasingEffectConfig> = z.union([
+  FreezeEffectSchema,
+  CreateEffectSchema,
+  CreateFromEffectSchema,
+  AssignEffectSchema,
+  AliasEffectSchema,
+  CaptureEffectSchema,
+  ImpureEffectSchema,
+  MutateEffectSchema,
+  MutateTransitiveConditionallySchema,
+  ApplyEffectSchema,
+]);
+
+export type AliasingSignatureConfig = {
+  receiver: string;
+  params: Array<string>;
+  rest: string | null;
+  returns: string;
+  effects: Array<AliasingEffectConfig>;
+  temporaries: Array<string>;
+};
+
+export const AliasingSignatureSchema: z.ZodType<AliasingSignatureConfig> =
+  z.object({
+    receiver: LifetimeIdSchema,
+    params: z.array(LifetimeIdSchema),
+    rest: LifetimeIdSchema.nullable(),
+    returns: LifetimeIdSchema,
+    effects: z.array(AliasingEffectSchema),
+    temporaries: z.array(LifetimeIdSchema),
+  });
+
 export type FunctionTypeConfig = {
   kind: 'function';
   positionalParams: Array<Effect>;
@@ -42,6 +235,7 @@ export type FunctionTypeConfig = {
   mutableOnlyIfOperandsAreMutable?: boolean | null | undefined;
   impure?: boolean | null | undefined;
   canonicalName?: string | null | undefined;
+  aliasing?: AliasingSignatureConfig | null | undefined;
 };
 export const FunctionTypeSchema: z.ZodType<FunctionTypeConfig> = z.object({
   kind: z.literal('function'),
@@ -54,6 +248,7 @@ export const FunctionTypeSchema: z.ZodType<FunctionTypeConfig> = z.object({
   mutableOnlyIfOperandsAreMutable: z.boolean().nullable().optional(),
   impure: z.boolean().nullable().optional(),
   canonicalName: z.string().nullable().optional(),
+  aliasing: AliasingSignatureSchema.nullable().optional(),
 });
 
 export type HookTypeConfig = {
@@ -63,6 +258,7 @@ export type HookTypeConfig = {
   returnType: TypeConfig;
   returnValueKind?: ValueKind | null | undefined;
   noAlias?: boolean | null | undefined;
+  aliasing?: AliasingSignatureConfig | null | undefined;
 };
 export const HookTypeSchema: z.ZodType<HookTypeConfig> = z.object({
   kind: z.literal('hook'),
@@ -71,6 +267,7 @@ export const HookTypeSchema: z.ZodType<HookTypeConfig> = z.object({
   returnType: z.lazy(() => TypeSchema),
   returnValueKind: ValueKindSchema.nullable().optional(),
   noAlias: z.boolean().nullable().optional(),
+  aliasing: AliasingSignatureSchema.nullable().optional(),
 });
 
 export type BuiltInTypeConfig =

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/typed-identity-function-frozen-input.expect.md

@@ -0,0 +1,117 @@
+
+## Input
+
+```javascript
+// @enableNewMutationAliasingModel
+
+import {
+  identity,
+  makeObject_Primitives,
+  typedIdentity,
+  useIdentity,
+  ValidateMemoization,
+} from 'shared-runtime';
+
+function Component({a, b}) {
+  // create a mutable value with input `a`
+  const x = makeObject_Primitives(a);
+
+  // freeze the value
+  useIdentity(x);
+
+  // known to pass-through via aliasing signature
+  const x2 = typedIdentity(x);
+
+  // Unknown function so we assume it conditionally mutates,
+  // but x2 is frozen so this downgrades to a read.
+  // x should *not* take b as a dependency
+  identity(x2, b);
+
+  return <ValidateMemoization inputs={[a]} output={x} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{a: 0, b: 0}],
+  sequentialRenders: [
+    {a: 0, b: 0},
+    {a: 1, b: 0},
+    {a: 1, b: 1},
+    {a: 0, b: 1},
+    {a: 0, b: 0},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel
+
+import {
+  identity,
+  makeObject_Primitives,
+  typedIdentity,
+  useIdentity,
+  ValidateMemoization,
+} from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(7);
+  const { a, b } = t0;
+  let t1;
+  if ($[0] !== a) {
+    t1 = makeObject_Primitives(a);
+    $[0] = a;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const x = t1;
+
+  useIdentity(x);
+
+  const x2 = typedIdentity(x);
+
+  identity(x2, b);
+  let t2;
+  if ($[2] !== a) {
+    t2 = [a];
+    $[2] = a;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== t2 || $[5] !== x) {
+    t3 = <ValidateMemoization inputs={t2} output={x} />;
+    $[4] = t2;
+    $[5] = x;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ a: 0, b: 0 }],
+  sequentialRenders: [
+    { a: 0, b: 0 },
+    { a: 1, b: 0 },
+    { a: 1, b: 1 },
+    { a: 0, b: 1 },
+    { a: 0, b: 0 },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"inputs":[0],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[1],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[1],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[0],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[0],"output":{"a":0,"b":"value1","c":true}}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/typed-identity-function-frozen-input.js

@@ -0,0 +1,39 @@
+// @enableNewMutationAliasingModel
+
+import {
+  identity,
+  makeObject_Primitives,
+  typedIdentity,
+  useIdentity,
+  ValidateMemoization,
+} from 'shared-runtime';
+
+function Component({a, b}) {
+  // create a mutable value with input `a`
+  const x = makeObject_Primitives(a);
+
+  // freeze the value
+  useIdentity(x);
+
+  // known to pass-through via aliasing signature
+  const x2 = typedIdentity(x);
+
+  // Unknown function so we assume it conditionally mutates,
+  // but x2 is frozen so this downgrades to a read.
+  // x should *not* take b as a dependency
+  identity(x2, b);
+
+  return <ValidateMemoization inputs={[a]} output={x} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{a: 0, b: 0}],
+  sequentialRenders: [
+    {a: 0, b: 0},
+    {a: 1, b: 0},
+    {a: 1, b: 1},
+    {a: 0, b: 1},
+    {a: 0, b: 0},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/typed-identity-function-mutable-input.expect.md

@@ -0,0 +1,112 @@
+
+## Input
+
+```javascript
+// @enableNewMutationAliasingModel
+
+import {
+  identity,
+  makeObject_Primitives,
+  typedIdentity,
+  useIdentity,
+  ValidateMemoization,
+} from 'shared-runtime';
+
+function Component({a, b}) {
+  // create a mutable value with input `a`
+  const x = makeObject_Primitives(a);
+
+  // known to pass-through via aliasing signature
+  const x2 = typedIdentity(x);
+
+  // Unknown function so we assume it conditionally mutates,
+  // and x is still mutable so
+  identity(x2, b);
+
+  return <ValidateMemoization inputs={[a, b]} output={x} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{a: 0, b: 0}],
+  sequentialRenders: [
+    {a: 0, b: 0},
+    {a: 1, b: 0},
+    {a: 1, b: 1},
+    {a: 0, b: 1},
+    {a: 0, b: 0},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel
+
+import {
+  identity,
+  makeObject_Primitives,
+  typedIdentity,
+  useIdentity,
+  ValidateMemoization,
+} from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(9);
+  const { a, b } = t0;
+  let x;
+  if ($[0] !== a || $[1] !== b) {
+    x = makeObject_Primitives(a);
+
+    const x2 = typedIdentity(x);
+
+    identity(x2, b);
+    $[0] = a;
+    $[1] = b;
+    $[2] = x;
+  } else {
+    x = $[2];
+  }
+  let t1;
+  if ($[3] !== a || $[4] !== b) {
+    t1 = [a, b];
+    $[3] = a;
+    $[4] = b;
+    $[5] = t1;
+  } else {
+    t1 = $[5];
+  }
+  let t2;
+  if ($[6] !== t1 || $[7] !== x) {
+    t2 = <ValidateMemoization inputs={t1} output={x} />;
+    $[6] = t1;
+    $[7] = x;
+    $[8] = t2;
+  } else {
+    t2 = $[8];
+  }
+  return t2;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ a: 0, b: 0 }],
+  sequentialRenders: [
+    { a: 0, b: 0 },
+    { a: 1, b: 0 },
+    { a: 1, b: 1 },
+    { a: 0, b: 1 },
+    { a: 0, b: 0 },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"inputs":[0,0],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[1,0],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[1,1],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[0,1],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[0,0],"output":{"a":0,"b":"value1","c":true}}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/typed-identity-function-mutable-input.js

@@ -0,0 +1,35 @@
+// @enableNewMutationAliasingModel
+
+import {
+  identity,
+  makeObject_Primitives,
+  typedIdentity,
+  useIdentity,
+  ValidateMemoization,
+} from 'shared-runtime';
+
+function Component({a, b}) {
+  // create a mutable value with input `a`
+  const x = makeObject_Primitives(a);
+
+  // known to pass-through via aliasing signature
+  const x2 = typedIdentity(x);
+
+  // Unknown function so we assume it conditionally mutates,
+  // and x is still mutable so
+  identity(x2, b);
+
+  return <ValidateMemoization inputs={[a, b]} output={x} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{a: 0, b: 0}],
+  sequentialRenders: [
+    {a: 0, b: 0},
+    {a: 1, b: 0},
+    {a: 1, b: 1},
+    {a: 0, b: 1},
+    {a: 0, b: 0},
+  ],
+};

compiler/packages/snap/src/sprout/shared-runtime-type-provider.ts

@@ -69,6 +69,22 @@ export function makeSharedRuntimeTypeProvider({
             returnValueKind: ValueKindEnum.Mutable,
             noAlias: true,
           },
+          typedIdentity: {
+            kind: 'function',
+            positionalParams: [EffectEnum.Read],
+            restParam: null,
+            calleeEffect: EffectEnum.Read,
+            returnType: {kind: 'type', name: 'Any'},
+            returnValueKind: ValueKindEnum.Mutable,
+            aliasing: {
+              receiver: '@receiver',
+              params: ['@value'],
+              rest: null,
+              returns: '@return',
+              temporaries: [],
+              effects: [{kind: 'Assign', from: '@value', into: '@return'}],
+            },
+          },
         },
       };
     } else if (moduleName === 'ReactCompilerTest') {

compiler/packages/snap/src/sprout/shared-runtime.ts

@@ -396,4 +396,8 @@ export function typedLog(...values: Array<any>): void {
   console.log(...values);
 }
 
+export function typedIdentity<T>(value: T): T {
+  return value;
+}
+
 export default typedLog;