[compiler] Consolidate HIRFunction return information

We now have `HIRFunction.returns: Place` as well as `returnType: Type`. I want to add additional return information, so as a first step i'm consolidating everything under an object at `HIRFunction.returns: {place: Place}`. We use the type of this place as the return type. Next step is to add more properties to this object to represent things like the return kind.

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

@@ -221,7 +221,6 @@ export function lower(
     params,
     fnType: bindings == null ? env.fnType : 'Other',
     returnTypeAnnotation: null, // TODO: extract the actual return type node if present
-    returnType: makeType(),
     returns: createTemporaryPlace(env, func.node.loc ?? GeneratedSource),
     body: builder.build(),
     context,

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

@@ -279,7 +279,6 @@ export type HIRFunction = {
   env: Environment;
   params: Array<Place | SpreadPattern>;
   returnTypeAnnotation: t.FlowType | t.TSType | null;
-  returnType: Type;
   returns: Place;
   context: Array<Place>;
   effects: Array<FunctionEffect> | null;

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

@@ -54,6 +54,8 @@ export function printFunction(fn: HIRFunction): string {
   let definition = '';
   if (fn.id !== null) {
     definition += fn.id;
+  } else {
+    definition += '<<anonymous>>';
   }
   if (fn.params.length !== 0) {
     definition +=
@@ -71,10 +73,8 @@ export function printFunction(fn: HIRFunction): string {
   } else {
     definition += '()';
   }
-  if (definition.length !== 0) {
-    output.push(definition);
-  }
-  output.push(`: ${printType(fn.returnType)} @ ${printPlace(fn.returns)}`);
+  definition += `: ${printPlace(fn.returns)}`;
+  output.push(definition);
   output.push(...fn.directives);
   output.push(printHIR(fn.body));
   return output.join('\n');

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutationAliasingRanges.ts

@@ -18,6 +18,7 @@ import {
   ValueKind,
   ValueReason,
   Place,
+  isPrimitiveType,
 } from '../HIR/HIR';
 import {
   eachInstructionLValue,
@@ -471,15 +472,15 @@ export function inferMutationAliasingRanges(
    * Here we populate an effect to create the return value as well as populating alias/capture
    * effects for how data flows between the params, context vars, and return.
    */
+  const returns = fn.returns.identifier;
   functionEffects.push({
     kind: 'Create',
     into: fn.returns,
-    value:
-      fn.returnType.kind === 'Primitive'
-        ? ValueKind.Primitive
-        : isJsxType(fn.returnType)
-          ? ValueKind.Frozen
-          : ValueKind.Mutable,
+    value: isPrimitiveType(returns)
+      ? ValueKind.Primitive
+      : isJsxType(returns.type)
+        ? ValueKind.Frozen
+        : ValueKind.Mutable,
     reason: ValueReason.KnownReturnSignature,
   });
   /**

compiler/packages/babel-plugin-react-compiler/src/Optimization/LowerContextAccess.ts

@@ -25,7 +25,6 @@ import {
   makeBlockId,
   makeInstructionId,
   makePropertyLiteral,
-  makeType,
   markInstructionIds,
   promoteTemporary,
   reversePostorderBlocks,
@@ -253,7 +252,6 @@ function emitSelectorFn(env: Environment, keys: Array<string>): Instruction {
     env,
     params: [obj],
     returnTypeAnnotation: null,
-    returnType: makeType(),
     returns: createTemporaryPlace(env, GeneratedSource),
     context: [],
     effects: null,

compiler/packages/babel-plugin-react-compiler/src/Optimization/OutlineJsx.ts

@@ -21,7 +21,6 @@ import {
   makeBlockId,
   makeIdentifierName,
   makeInstructionId,
-  makeType,
   ObjectProperty,
   Place,
   promoteTemporary,
@@ -368,7 +367,6 @@ function emitOutlinedFn(
     env,
     params: [propsObj],
     returnTypeAnnotation: null,
-    returnType: makeType(),
     returns: createTemporaryPlace(env, GeneratedSource),
     context: [],
     effects: null,

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/CodegenReactiveFunction.ts

@@ -349,11 +349,9 @@ function codegenReactiveFunction(
   fn: ReactiveFunction,
 ): Result<CodegenFunction, CompilerError> {
   for (const param of fn.params) {
-    if (param.kind === 'Identifier') {
-      cx.temp.set(param.identifier.declarationId, null);
-    } else {
-      cx.temp.set(param.place.identifier.declarationId, null);
-    }
+    const place = param.kind === 'Identifier' ? param : param.place;
+    cx.temp.set(place.identifier.declarationId, null);
+    cx.declare(place.identifier);
   }
 
   const params = fn.params.map(param => convertParameter(param));
@@ -1183,7 +1181,7 @@ function codegenTerminal(
               ? codegenPlaceToExpression(cx, case_.test)
               : null;
           const block = codegenBlock(cx, case_.block!);
-          return t.switchCase(test, [block]);
+          return t.switchCase(test, block.body.length === 0 ? [] : [block]);
         }),
       );
     }

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/ExtractScopeDeclarationsFromDestructuring.ts

@@ -79,6 +79,10 @@ export function extractScopeDeclarationsFromDestructuring(
   fn: ReactiveFunction,
 ): void {
   const state = new State(fn.env);
+  for (const param of fn.params) {
+    const place = param.kind === 'Identifier' ? param : param.place;
+    state.declared.add(place.identifier.declarationId);
+  }
   visitReactiveFunction(fn, new Visitor(), state);
 }
 

compiler/packages/babel-plugin-react-compiler/src/TypeInference/InferTypes.ts

@@ -90,7 +90,8 @@ function apply(func: HIRFunction, unifier: Unifier): void {
       }
     }
   }
-  func.returnType = unifier.get(func.returnType);
+  const returns = func.returns.identifier;
+  returns.type = unifier.get(returns.type);
 }
 
 type TypeEquation = {
@@ -143,12 +144,12 @@ function* generate(
     }
   }
   if (returnTypes.length > 1) {
-    yield equation(func.returnType, {
+    yield equation(func.returns.identifier.type, {
       kind: 'Phi',
       operands: returnTypes,
     });
   } else if (returnTypes.length === 1) {
-    yield equation(func.returnType, returnTypes[0]!);
+    yield equation(func.returns.identifier.type, returnTypes[0]!);
   }
 }
 
@@ -407,7 +408,7 @@ function* generateInstructionTypes(
       yield equation(left, {
         kind: 'Function',
         shapeId: BuiltInFunctionId,
-        return: value.loweredFunc.func.returnType,
+        return: value.loweredFunc.func.returns.identifier.type,
         isConstructor: false,
       });
       break;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/block-scoping-switch-variable-scoping.expect.md

@@ -50,8 +50,7 @@ function Component(props) {
       console.log(handlers.value);
       break bb0;
     }
-    default: {
-    }
+    default:
   }
 
   t0 = handlers;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/dominator.expect.md

@@ -67,8 +67,7 @@ function Component(props) {
     case "b": {
       break bb1;
     }
-    case "c": {
-    }
+    case "c":
     default: {
       x = 6;
     }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-reassign-props.expect.md

@@ -0,0 +1,65 @@
+
+## Input
+
+```javascript
+import {Stringify, useIdentity} from 'shared-runtime';
+
+function Component({other, ...props}, ref) {
+  [props, ref] = useIdentity([props, ref]);
+  return <Stringify props={props} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{a: 0, b: 'hello', children: <div>Hello</div>}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { Stringify, useIdentity } from "shared-runtime";
+
+function Component(t0, ref) {
+  const $ = _c(7);
+  let props;
+  if ($[0] !== t0) {
+    let { other, ...t1 } = t0;
+    props = t1;
+    $[0] = t0;
+    $[1] = props;
+  } else {
+    props = $[1];
+  }
+  let t1;
+  if ($[2] !== props || $[3] !== ref) {
+    t1 = [props, ref];
+    $[2] = props;
+    $[3] = ref;
+    $[4] = t1;
+  } else {
+    t1 = $[4];
+  }
+  [props, ref] = useIdentity(t1);
+  let t2;
+  if ($[5] !== props) {
+    t2 = <Stringify props={props} />;
+    $[5] = props;
+    $[6] = t2;
+  } else {
+    t2 = $[6];
+  }
+  return t2;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ a: 0, b: "hello", children: <div>Hello</div> }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"props":{"a":0,"b":"hello","children":{"type":"div","key":null,"props":{"children":"Hello"},"_owner":"[[ cyclic ref *3 ]]","_store":{}}}}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-reassign-props.js

@@ -0,0 +1,11 @@
+import {Stringify, useIdentity} from 'shared-runtime';
+
+function Component({other, ...props}, ref) {
+  [props, ref] = useIdentity([props, ref]);
+  return <Stringify props={props} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{a: 0, b: 'hello', children: <div>Hello</div>}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/reverse-postorder.expect.md

@@ -50,10 +50,8 @@ function Component(props) {
       case 1: {
         break bb0;
       }
-      case 2: {
-      }
-      default: {
-      }
+      case 2:
+      default:
     }
   } else {
     if (props.cond2) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ssa-switch.expect.md

@@ -41,8 +41,7 @@ function foo() {
     case 2: {
       break bb0;
     }
-    default: {
-    }
+    default:
   }
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/switch-with-fallthrough.expect.md

@@ -43,22 +43,17 @@ export const FIXTURE_ENTRYPOINT = {
 ```javascript
 function foo(x) {
   bb0: switch (x) {
-    case 0: {
-    }
-    case 1: {
-    }
+    case 0:
+    case 1:
     case 2: {
       break bb0;
     }
     case 3: {
       break bb0;
     }
-    case 4: {
-    }
-    case 5: {
-    }
-    default: {
-    }
+    case 4:
+    case 5:
+    default:
   }
 }