[compiler] Fix for scopes with unreachable fallthroughs

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

@@ -175,6 +175,41 @@ export function alignReactiveScopesToBlockScopesHIR(fn: HIRFunction): void {
       if (node != null) {
         valueBlockNodes.set(fallthrough, node);
       }
+    } else if (terminal.kind === 'goto') {
+      /**
+       * If we encounter a goto that is not to the natural fallthrough of the current
+       * block (not the topmost fallthrough on the stack), then this is a goto to a
+       * label. Any scopes that extend beyond the goto must be extended to include
+       * the labeled range, so that the break statement doesn't accidentally jump
+       * out of the scope. We do this by extending the start and end of the scope's
+       * range to the label and its fallthrough respectively.
+       */
+      const start = activeBlockFallthroughRanges.find(
+        range => range.fallthrough === terminal.block,
+      );
+      if (start != null && start !== activeBlockFallthroughRanges.at(-1)) {
+        const fallthroughBlock = fn.body.blocks.get(start.fallthrough)!;
+        const firstId =
+          fallthroughBlock.instructions[0]?.id ?? fallthroughBlock.terminal.id;
+        for (const scope of activeScopes) {
+          /**
+           * activeScopes is only filtered at block start points, so some of the
+           * scopes may not actually be active anymore, ie we've past their end
+           * instruction. Only extend ranges for scopes that are actually active.
+           *
+           * TODO: consider pruning activeScopes per instruction
+           */
+          if (scope.range.end <= terminal.id) {
+            continue;
+          }
+          scope.range.start = makeInstructionId(
+            Math.min(start.range.start, scope.range.start),
+          );
+          scope.range.end = makeInstructionId(
+            Math.max(firstId, scope.range.end),
+          );
+        }
+      }
     }
 
     /*

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/align-scopes-reactive-scope-overlaps-if.expect.md

@@ -46,14 +46,16 @@ function useFoo(t0) {
     t1 = $[0];
   }
   let items = t1;
-  bb0: if ($[1] !== cond) {
-    if (cond) {
-      items = [];
-    } else {
-      break bb0;
-    }
+  if ($[1] !== cond) {
+    bb0: {
+      if (cond) {
+        items = [];
+      } else {
+        break bb0;
+      }
 
-    items.push(2);
+      items.push(2);
+    }
     $[1] = cond;
     $[2] = items;
   } else {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/mutation-within-jsx-and-break.expect.md

@@ -49,26 +49,27 @@ import {
 } from "shared-runtime";
 
 function useFoo(t0) {
-  const $ = _c(3);
+  const $ = _c(4);
   const { data } = t0;
   let obj;
   let myDiv = null;
-  bb0: if (data.cond) {
-    if ($[0] !== data.cond1) {
+  if ($[0] !== data.cond || $[1] !== data.cond1) {
+    bb0: if (data.cond) {
       obj = makeObject_Primitives();
       if (data.cond1) {
         myDiv = <Stringify value={mutateAndReturn(obj)} />;
         break bb0;
       }
 
       mutate(obj);
-      $[0] = data.cond1;
-      $[1] = obj;
-      $[2] = myDiv;
-    } else {
-      obj = $[1];
-      myDiv = $[2];
     }
+    $[0] = data.cond;
+    $[1] = data.cond1;
+    $[2] = obj;
+    $[3] = myDiv;
+  } else {
+    obj = $[2];
+    myDiv = $[3];
   }
   return myDiv;
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/propagate-scope-deps-hir-fork/useMemo-multiple-if-else.expect.md

@@ -34,17 +34,16 @@ import { c as _c } from "react/compiler-runtime"; // @enablePropagateDepsInHIR
 import { useMemo } from "react";
 
 function Component(props) {
-  const $ = _c(6);
+  const $ = _c(5);
   let t0;
-  bb0: {
-    let y;
-    if (
-      $[0] !== props.a ||
-      $[1] !== props.b ||
-      $[2] !== props.cond ||
-      $[3] !== props.cond2
-    ) {
-      y = [];
+  if (
+    $[0] !== props.a ||
+    $[1] !== props.b ||
+    $[2] !== props.cond ||
+    $[3] !== props.cond2
+  ) {
+    bb0: {
+      const y = [];
       if (props.cond) {
         y.push(props.a);
       }
@@ -54,17 +53,15 @@ function Component(props) {
       }
 
       y.push(props.b);
-      $[0] = props.a;
-      $[1] = props.b;
-      $[2] = props.cond;
-      $[3] = props.cond2;
-      $[4] = y;
-      $[5] = t0;
-    } else {
-      y = $[4];
-      t0 = $[5];
+      t0 = y;
     }
-    t0 = y;
+    $[0] = props.a;
+    $[1] = props.b;
+    $[2] = props.cond;
+    $[3] = props.cond2;
+    $[4] = t0;
+  } else {
+    t0 = $[4];
   }
   const x = t0;
   return x;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-useMemo-if-else-both-early-return.expect.md

@@ -0,0 +1,118 @@
+
+## Input
+
+```javascript
+import {useMemo} from 'react';
+import {
+  makeObject_Primitives,
+  mutate,
+  Stringify,
+  ValidateMemoization,
+} from 'shared-runtime';
+
+function Component({cond}) {
+  const memoized = useMemo(() => {
+    const value = makeObject_Primitives();
+    if (cond) {
+      return value;
+    } else {
+      mutate(value);
+      return value;
+    }
+  }, [cond]);
+  return <ValidateMemoization inputs={[cond]} output={memoized} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{cond: false}],
+  sequentialRenders: [
+    {cond: false},
+    {cond: false},
+    {cond: true},
+    {cond: true},
+    {cond: false},
+    {cond: true},
+    {cond: false},
+    {cond: true},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { useMemo } from "react";
+import {
+  makeObject_Primitives,
+  mutate,
+  Stringify,
+  ValidateMemoization,
+} from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(7);
+  const { cond } = t0;
+  let t1;
+  if ($[0] !== cond) {
+    const value = makeObject_Primitives();
+    if (cond) {
+      t1 = value;
+    } else {
+      mutate(value);
+      t1 = value;
+    }
+    $[0] = cond;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const memoized = t1;
+  let t2;
+  if ($[2] !== cond) {
+    t2 = [cond];
+    $[2] = cond;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== memoized || $[5] !== t2) {
+    t3 = <ValidateMemoization inputs={t2} output={memoized} />;
+    $[4] = memoized;
+    $[5] = t2;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ cond: false }],
+  sequentialRenders: [
+    { cond: false },
+    { cond: false },
+    { cond: true },
+    { cond: true },
+    { cond: false },
+    { cond: true },
+    { cond: false },
+    { cond: true },
+  ],
+};
+
+```
+
+### Eval output
+(kind: ok) <div>{"inputs":[false],"output":{"a":0,"b":"value1","c":true,"wat0":"joe"}}</div>
+<div>{"inputs":[false],"output":{"a":0,"b":"value1","c":true,"wat0":"joe"}}</div>
+<div>{"inputs":[true],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[true],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[false],"output":{"a":0,"b":"value1","c":true,"wat0":"joe"}}</div>
+<div>{"inputs":[true],"output":{"a":0,"b":"value1","c":true}}</div>
+<div>{"inputs":[false],"output":{"a":0,"b":"value1","c":true,"wat0":"joe"}}</div>
+<div>{"inputs":[true],"output":{"a":0,"b":"value1","c":true}}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-useMemo-if-else-both-early-return.js

@@ -0,0 +1,35 @@
+import {useMemo} from 'react';
+import {
+  makeObject_Primitives,
+  mutate,
+  Stringify,
+  ValidateMemoization,
+} from 'shared-runtime';
+
+function Component({cond}) {
+  const memoized = useMemo(() => {
+    const value = makeObject_Primitives();
+    if (cond) {
+      return value;
+    } else {
+      mutate(value);
+      return value;
+    }
+  }, [cond]);
+  return <ValidateMemoization inputs={[cond]} output={memoized} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{cond: false}],
+  sequentialRenders: [
+    {cond: false},
+    {cond: false},
+    {cond: true},
+    {cond: true},
+    {cond: false},
+    {cond: true},
+    {cond: false},
+    {cond: true},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useMemo-multiple-if-else.expect.md

@@ -33,17 +33,16 @@ import { c as _c } from "react/compiler-runtime";
 import { useMemo } from "react";
 
 function Component(props) {
-  const $ = _c(6);
+  const $ = _c(5);
   let t0;
-  bb0: {
-    let y;
-    if (
-      $[0] !== props.a ||
-      $[1] !== props.b ||
-      $[2] !== props.cond ||
-      $[3] !== props.cond2
-    ) {
-      y = [];
+  if (
+    $[0] !== props.a ||
+    $[1] !== props.b ||
+    $[2] !== props.cond ||
+    $[3] !== props.cond2
+  ) {
+    bb0: {
+      const y = [];
       if (props.cond) {
         y.push(props.a);
       }
@@ -53,17 +52,15 @@ function Component(props) {
       }
 
       y.push(props.b);
-      $[0] = props.a;
-      $[1] = props.b;
-      $[2] = props.cond;
-      $[3] = props.cond2;
-      $[4] = y;
-      $[5] = t0;
-    } else {
-      y = $[4];
-      t0 = $[5];
+      t0 = y;
     }
-    t0 = y;
+    $[0] = props.a;
+    $[1] = props.b;
+    $[2] = props.cond;
+    $[3] = props.cond2;
+    $[4] = t0;
+  } else {
+    t0 = $[4];
   }
   const x = t0;
   return x;