From cedaee5b03e94ee5f41f3683dd61d8e917fe29a2 Mon Sep 17 00:00:00 2001
From: Joe Savona <joesavona@fb.com>
Date: Tue, 20 Dec 2022 11:06:07 -0800
Subject: [PATCH] Codegen for scopes without dependencies

Completes a todo for the `if` condition of scopes without any inputs. In this
case since there are no inputs we can check for changes, we check if the first
_output_ cache slot is set to the sentinel.

For this to work we need to ensure that all scopes have at least one output,
which isn't currently the case. Dead code can produce output-less sentinels. So
this PR also adds a pass to find scopes w/o any outputs and convert them to
regular blocks. We could in theory also just delete them, but for now let's be
more conservative. This is something we'd want to highlight as a diagnostic in
an IDE, though existing dead code linters would almost certainly find this case
too.
---
 compiler/forget/src/CompilerPipeline.ts       |   2 +
 .../ReactiveScopes/CodegenReactiveFunction.ts |  42 +++++--
 .../src/ReactiveScopes/PruneUnusedScopes.ts   |  52 ++++++++
 compiler/forget/src/ReactiveScopes/index.ts   |   1 +
 .../forget/src/ReactiveScopes/visitors.ts     |  52 ++++++++
 .../_bug_conditional-break-labeled.expect.md  |  41 ++----
 .../alias-nested-member-path-mutate.expect.md |  29 ++---
 .../hir/alias-nested-member-path.expect.md    |   2 +-
 .../hir/assignment-variations.expect.md       |  15 +--
 .../src/__tests__/fixtures/hir/call.expect.md |  38 +++---
 .../fixtures/hir/conditional-break.expect.md  |  41 ++----
 .../fixtures/hir/constructor.expect.md        |  38 +++---
 .../hir/dependencies-outputs.expect.md        |  35 ++----
 .../fixtures/hir/dependencies.expect.md       |  65 ++++------
 .../fixtures/hir/extend-scopes-if.expect.md   |  36 ++----
 .../fixtures/hir/frozen-after-alias.expect.md |   2 +-
 .../fixtures/hir/hook-call.expect.md          |   2 +-
 .../hir/hooks-freeze-arguments.expect.md      |   2 +-
 .../fixtures/hir/inverted-if.expect.md        |  30 ++---
 .../fixtures/hir/jsx-fragment.expect.md       |   2 +-
 .../fixtures/hir/logical-expression.expect.md |   6 +-
 .../hir/mutable-lifetime-loops.expect.md      | 113 ++++++++---------
 .../mutable-lifetime-with-aliasing.expect.md  | 108 ++++++++--------
 .../hir/mutable-liverange-loop.expect.md      | 118 +++++++++---------
 ...g-scopes-interleaved-by-terminal.expect.md |  33 ++---
 .../overlapping-scopes-interleaved.expect.md  |  26 ++--
 .../hir/overlapping-scopes-shadowed.expect.md |  35 ++----
 .../hir/overlapping-scopes-while.expect.md    |  38 ++----
 .../hir/reactive-scope-grouping.expect.md     |   4 +-
 .../hir/reassignment-conditional.expect.md    |  37 +++---
 .../fixtures/hir/reassignment.expect.md       |  39 +++---
 .../fixtures/hir/simple-alias.expect.md       |  13 +-
 .../__tests__/fixtures/hir/simple.expect.md   |   2 +-
 .../hir/ssa-arrayexpression.expect.md         |   2 +-
 .../fixtures/hir/ssa-call-jsx-2.expect.md     |  41 +++---
 .../fixtures/hir/ssa-call-jsx.expect.md       |  38 +++---
 .../hir/ssa-complex-multiple-if.expect.md     |   2 +-
 .../hir/ssa-complex-single-if.expect.md       |   2 +-
 .../fixtures/hir/ssa-for-of.expect.md         |   9 +-
 .../hir/ssa-for-trivial-update.expect.md      |   2 +-
 .../__tests__/fixtures/hir/ssa-for.expect.md  |   2 +-
 .../hir/ssa-nested-partial-phi.expect.md      |  34 ++---
 .../fixtures/hir/ssa-newexpression.expect.md  |   2 +-
 .../hir/ssa-objectexpression-phi.expect.md    |   2 +-
 .../hir/ssa-objectexpression.expect.md        |   2 +-
 .../hir/ssa-property-alias-if.expect.md       |   4 +-
 ...-property-alias-mutate-inside-if.expect.md |   2 +-
 .../hir/ssa-property-alias-mutate.expect.md   |   2 +-
 .../fixtures/hir/ssa-property-call.expect.md  |   2 +-
 .../hir/ssa-property-mutate-2.expect.md       |   2 +-
 .../hir/ssa-property-mutate-alias.expect.md   |   2 +-
 .../hir/ssa-property-mutate.expect.md         |   2 +-
 .../fixtures/hir/ssa-property.expect.md       |   2 +-
 .../fixtures/hir/ssa-return.expect.md         |   2 +-
 .../fixtures/hir/ssa-simple-phi.expect.md     |   2 +-
 .../fixtures/hir/ssa-switch.expect.md         |   2 +-
 .../fixtures/hir/ssa-throw.expect.md          |   2 +-
 .../fixtures/hir/ssa-while.expect.md          |   2 +-
 .../__tests__/fixtures/hir/switch.expect.md   |  10 +-
 .../hir/transitive-alias-fields.expect.md     |  37 +++---
 .../type-args-test-binary-operator.expect.md  |   9 +-
 .../hir/type-binary-operator.expect.md        |  13 +-
 .../fixtures/hir/type-field-load.expect.md    |   2 +-
 .../type-test-field-load-binary-op.expect.md  |   4 +-
 .../hir/type-test-field-store.expect.md       |   4 +-
 .../hir/type-test-polymorphic.expect.md       |   4 +-
 .../type-test-return-type-inference.expect.md |  22 +---
 67 files changed, 613 insertions(+), 757 deletions(-)
 create mode 100644 compiler/forget/src/ReactiveScopes/PruneUnusedScopes.ts
 create mode 100644 compiler/forget/src/ReactiveScopes/visitors.ts

diff --git a/compiler/forget/src/CompilerPipeline.ts b/compiler/forget/src/CompilerPipeline.ts
index 75c1381aaa..3532f92eef 100644
--- a/compiler/forget/src/CompilerPipeline.ts
+++ b/compiler/forget/src/CompilerPipeline.ts
@@ -23,6 +23,7 @@ import {
   printReactiveFunction,
   propagateScopeDependencies,
   pruneUnusedLabels,
+  pruneUnusedScopes,
 } from "./ReactiveScopes";
 import { eliminateRedundantPhi, enterSSA, leaveSSA } from "./SSA";
 import { logHIRFunction } from "./Utils/logger";
@@ -69,6 +70,7 @@ export default function (
   pruneUnusedLabels(reactiveFunction);
   flattenReactiveLoops(reactiveFunction);
   propagateScopeDependencies(reactiveFunction);
+  pruneUnusedScopes(reactiveFunction);
   const scopes = printReactiveFunction(reactiveFunction);
   const ast = codegenReactiveFunction(reactiveFunction);
 
diff --git a/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts b/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts
index d444d9f7bb..9434866701 100644
--- a/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts
+++ b/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts
@@ -166,8 +166,12 @@ function codegenReactiveScope(
       )
     );
   }
+  let firstOutputIndex: number | null = null;
   for (const output of scope.outputs) {
     const index = cx.nextCacheIndex;
+    if (firstOutputIndex === null) {
+      firstOutputIndex = index;
+    }
 
     // TODO @josephsavona: ensure change and temp variables have non-conflicting names
     output.name ??= `t${index}`;
@@ -194,16 +198,34 @@ function codegenReactiveScope(
       )
     );
   }
-  const testCondition =
-    (changeIdentifiers as Array<t.Expression>).reduce(
-      (acc: t.Expression | null, ident: t.Expression) => {
-        if (acc == null) {
-          return ident;
-        }
-        return t.logicalExpression("||", acc, ident);
-      },
-      null as t.Expression | null
-    ) ?? t.booleanLiteral(true); // TODO @josephsavona handle case of empty dependencies
+  invariant(
+    firstOutputIndex !== null,
+    "Expected scope '@%s' to have at least one output",
+    scope.id
+  );
+  let testCondition = (changeIdentifiers as Array<t.Expression>).reduce(
+    (acc: t.Expression | null, ident: t.Expression) => {
+      if (acc == null) {
+        return ident;
+      }
+      return t.logicalExpression("||", acc, ident);
+    },
+    null as t.Expression | null
+  );
+  if (testCondition === null) {
+    testCondition = t.binaryExpression(
+      "===",
+      t.memberExpression(
+        t.identifier("$"),
+        t.numericLiteral(firstOutputIndex),
+        true
+      ),
+      t.callExpression(
+        t.memberExpression(t.identifier("Symbol"), t.identifier("for")),
+        [t.stringLiteral("react.memo_cache_sentinel")]
+      )
+    );
+  }
 
   const computationBlock = codegenBlock(cx, block);
   computationBlock.body.push(...cacheStoreStatements);
diff --git a/compiler/forget/src/ReactiveScopes/PruneUnusedScopes.ts b/compiler/forget/src/ReactiveScopes/PruneUnusedScopes.ts
new file mode 100644
index 0000000000..fe5e38387e
--- /dev/null
+++ b/compiler/forget/src/ReactiveScopes/PruneUnusedScopes.ts
@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import { ReactiveBlock, ReactiveFunction } from "../HIR/HIR";
+import { assertExhaustive } from "../Utils/utils";
+import { mapTerminalBlocks } from "./visitors";
+
+/**
+ * Converts scopes without outputs into regular blocks.
+ */
+export function pruneUnusedScopes(fn: ReactiveFunction): void {
+  fn.body = visitBlock(fn.body);
+}
+
+function visitBlock(block: ReactiveBlock): ReactiveBlock {
+  let nextBlock: ReactiveBlock | null = null;
+  for (let i = 0; i < block.length; i++) {
+    const stmt = block[i]!;
+    switch (stmt.kind) {
+      case "terminal": {
+        mapTerminalBlocks(stmt.terminal, visitBlock);
+        break;
+      }
+      case "instruction": {
+        break;
+      }
+      case "scope": {
+        stmt.instructions = visitBlock(stmt.instructions);
+        if (stmt.scope.outputs.size === 0) {
+          nextBlock ??= block.slice(0, i);
+          nextBlock.push(...stmt.instructions);
+          continue;
+        }
+        break;
+      }
+      default: {
+        assertExhaustive(
+          stmt,
+          `Unexpected statement kind '${(stmt as any).kind}'`
+        );
+      }
+    }
+    if (nextBlock !== null) {
+      nextBlock.push(stmt);
+    }
+  }
+  return nextBlock ?? block;
+}
diff --git a/compiler/forget/src/ReactiveScopes/index.ts b/compiler/forget/src/ReactiveScopes/index.ts
index 3fcfa28bdd..8491e3b914 100644
--- a/compiler/forget/src/ReactiveScopes/index.ts
+++ b/compiler/forget/src/ReactiveScopes/index.ts
@@ -13,3 +13,4 @@ export { inferReactiveScopeVariables } from "./InferReactiveScopeVariables";
 export { printReactiveFunction } from "./PrintReactiveFunction";
 export { propagateScopeDependencies } from "./PropagateScopeDependencies";
 export { pruneUnusedLabels } from "./PruneUnusedLabels";
+export { pruneUnusedScopes } from "./PruneUnusedScopes";
diff --git a/compiler/forget/src/ReactiveScopes/visitors.ts b/compiler/forget/src/ReactiveScopes/visitors.ts
new file mode 100644
index 0000000000..c46c3a7c7d
--- /dev/null
+++ b/compiler/forget/src/ReactiveScopes/visitors.ts
@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import { ReactiveBlock, ReactiveTerminal } from "../HIR/HIR";
+import { assertExhaustive } from "../Utils/utils";
+
+export function mapTerminalBlocks(
+  terminal: ReactiveTerminal,
+  fn: (block: ReactiveBlock) => ReactiveBlock
+): void {
+  switch (terminal.kind) {
+    case "break":
+    case "continue":
+    case "return":
+    case "throw": {
+      break;
+    }
+    case "for": {
+      terminal.loop = fn(terminal.loop);
+      break;
+    }
+    case "while": {
+      terminal.loop = fn(terminal.loop);
+      break;
+    }
+    case "if": {
+      terminal.consequent = fn(terminal.consequent);
+      if (terminal.alternate !== null) {
+        terminal.alternate = fn(terminal.alternate);
+      }
+      break;
+    }
+    case "switch": {
+      for (const case_ of terminal.cases) {
+        if (case_.block !== undefined) {
+          case_.block = fn(case_.block);
+        }
+      }
+      break;
+    }
+    default: {
+      assertExhaustive(
+        terminal,
+        `Unexpected terminal kind '${(terminal as any).kind}'`
+      );
+    }
+  }
+}
diff --git a/compiler/forget/src/__tests__/fixtures/hir/_bug_conditional-break-labeled.expect.md b/compiler/forget/src/__tests__/fixtures/hir/_bug_conditional-break-labeled.expect.md
index f8b8b37698..ab354c4b22 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/_bug_conditional-break-labeled.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/_bug_conditional-break-labeled.expect.md
@@ -43,15 +43,13 @@ bb1:
 function Component(
   props,
 ) {
-  scope @0 [1:7] deps=[read props$3.a, read props$3.b, read props$3.d, read props$3.c] out=[] {
-    [1] Const mutate a$4_@0[1:7] = Array []
-    [2] Call mutate a$4_@0.push(read props$3.a)
-    if (read props$3.b) {
-      [6] Call mutate a$4_@0.push(read props$3.d)
-      return freeze a$4_@0
-    }
-    [4] Call mutate a$4_@0.push(read props$3.c)
+  [1] Const mutate a$4_@0[1:7] = Array []
+  [2] Call mutate a$4_@0.push(read props$3.a)
+  if (read props$3.b) {
+    [6] Call mutate a$4_@0.push(read props$3.d)
+    return freeze a$4_@0
   }
+  [4] Call mutate a$4_@0.push(read props$3.c)
 }
 
 ```
@@ -60,27 +58,14 @@ function Component(
 
 ```javascript
 function Component$0(props$3) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== props$3.a;
-  const c_1 = $[1] !== props$3.b;
-  const c_2 = $[2] !== props$3.d;
-  const c_3 = $[3] !== props$3.c;
-  if (c_0 || c_1 || c_2 || c_3) {
-    const a$4 = [];
-    a$4.push(props$3.a);
-
-    if (props$3.b) {
-      a$4.push(props$3.d);
-      return a$4;
-    }
-
-    a$4.push(props$3.c);
-    $[0] = props$3.a;
-    $[1] = props$3.b;
-    $[2] = props$3.d;
-    $[3] = props$3.c;
-  } else {
+  const a$4 = [];
+  a$4.push(props$3.a);
+  if (props$3.b) {
+    a$4.push(props$3.d);
+    return a$4;
   }
+
+  a$4.push(props$3.c);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path-mutate.expect.md b/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path-mutate.expect.md
index 1bfec4ea09..bec0c01fec 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path-mutate.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path-mutate.expect.md
@@ -31,14 +31,12 @@ bb0:
 ```
 function component(
 ) {
-  scope @0 [1:7] deps=[] out=[] {
-    [1] Const mutate z$5_@0[1:7] = Array []
-    [2] Const mutate y$6_@0:TObject[1:7] = Object {  }
-    [3] Reassign mutate y$6_@0.z[1:7] = read z$5_@0
-    [4] Const mutate x$7_@0:TObject[1:7] = Object {  }
-    [5] Reassign mutate x$7_@0.y[1:7] = read y$6_@0:TObject
-    [6] Call mutate mutate$4:TFunction(mutate x$7_@0.y.z)
-  }
+  [1] Const mutate z$5_@0[1:7] = Array []
+  [2] Const mutate y$6_@0:TObject[1:7] = Object {  }
+  [3] Reassign mutate y$6_@0.z[1:7] = read z$5_@0
+  [4] Const mutate x$7_@0:TObject[1:7] = Object {  }
+  [5] Reassign mutate x$7_@0.y[1:7] = read y$6_@0:TObject
+  [6] Call mutate mutate$4:TFunction(mutate x$7_@0.y.z)
   return
 }
 
@@ -48,15 +46,12 @@ function component(
 
 ```javascript
 function component$0() {
-  if (true) {
-    const z$5 = [];
-    const y$6 = {};
-    y$6.z = z$5;
-    const x$7 = {};
-    x$7.y = y$6;
-    mutate$4(x$7.y.z);
-  } else {
-  }
+  const z$5 = [];
+  const y$6 = {};
+  y$6.z = z$5;
+  const x$7 = {};
+  x$7.y = y$6;
+  mutate$4(x$7.y.z);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path.expect.md b/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path.expect.md
index b1167bf4d6..f503b73597 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/alias-nested-member-path.expect.md
@@ -52,7 +52,7 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let z$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     z$4 = [];
     $[0] = z$4;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md b/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md
index 83308f069f..e391fd7876 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/assignment-variations.expect.md
@@ -76,11 +76,9 @@ function g(
   a,
 ) {
   [1] Const mutate $5:TPrimitive = 1
-  scope @0 [0:5] deps=[] out=[] {
-    [2] Reassign mutate a$4_@0.b.c[0:5] = Binary read a$4_@0.b.c + read $5:TPrimitive
-    [3] Const mutate $6:TPrimitive = 2
-    [4] Reassign mutate a$4_@0.b.c[0:5] = Binary read a$4_@0.b.c * read $6:TPrimitive
-  }
+  [2] Reassign mutate a$4_@0.b.c[0:5] = Binary read a$4_@0.b.c + read $5:TPrimitive
+  [3] Const mutate $6:TPrimitive = 2
+  [4] Reassign mutate a$4_@0.b.c[0:5] = Binary read a$4_@0.b.c * read $6:TPrimitive
   return
 }
 
@@ -90,11 +88,8 @@ function g(
 
 ```javascript
 function g$0(a$4) {
-  if (true) {
-    a$4.c.b = a$4.b.c + 1;
-    a$4.c.b = a$4.b.c * 2;
-  } else {
-  }
+  a$4.c.b = a$4.b.c + 1;
+  a$4.c.b = a$4.b.c * 2;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/call.expect.md b/compiler/forget/src/__tests__/fixtures/hir/call.expect.md
index ec62da2830..8f9472bbd7 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/call.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/call.expect.md
@@ -49,8 +49,8 @@ bb0:
   [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
   [6] Call mutate foo$4:TFunction(mutate b$11_@0:TObject)
   [7] Const mutate $14:TPrimitive = "div"
-  [8] Const mutate t5$15_@2 = JSX <read $14:TPrimitive a={read a$10_@0} b={freeze b$11_@0:TObject} ></read $14:TPrimitive>
-  [9] Return read t5$15_@2
+  [8] Const mutate t4$15_@2 = JSX <read $14:TPrimitive a={read a$10_@0} b={freeze b$11_@0:TObject} ></read $14:TPrimitive>
+  [9] Return read t4$15_@2
 ```
 
 ## Reactive Scopes
@@ -64,9 +64,7 @@ function Component(
     [2] Const mutate b$11_@0:TObject[1:7] = Object {  }
     [3] Call mutate foo$4:TFunction(mutate a$10_@0, mutate b$11_@0:TObject)
     [4] Const mutate $12:TPrimitive = "div"
-    scope @1 [5:6] deps=[freeze a$10_@0] out=[] {
-      [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
-    }
+    [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
     [6] Call mutate foo$4:TFunction(mutate b$11_@0:TObject)
   }
   [7] Const mutate $14:TPrimitive = "div"
@@ -85,18 +83,12 @@ function Component$0(props$9) {
   const $ = React.useMemoCache();
   let a$10;
   let b$11;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$10 = [];
     b$11 = {};
     foo$4(a$10, b$11);
-    const c_2 = $[2] !== a$10;
 
-    if (c_2) {
-      const _$13 = <div a={a$10}></div>;
-
-      $[2] = a$10;
-    } else {
-    }
+    const _$13 = <div a={a$10}></div>;
 
     foo$4(b$11);
     $[0] = a$10;
@@ -106,20 +98,20 @@ function Component$0(props$9) {
     b$11 = $[1];
   }
 
-  const c_3 = $[3] !== a$10;
-  const c_4 = $[4] !== b$11;
-  let t5$15;
+  const c_2 = $[2] !== a$10;
+  const c_3 = $[3] !== b$11;
+  let t4$15;
 
-  if (c_3 || c_4) {
-    t5$15 = <div a={a$10} b={b$11}></div>;
-    $[3] = a$10;
-    $[4] = b$11;
-    $[5] = t5$15;
+  if (c_2 || c_3) {
+    t4$15 = <div a={a$10} b={b$11}></div>;
+    $[2] = a$10;
+    $[3] = b$11;
+    $[4] = t4$15;
   } else {
-    t5$15 = $[5];
+    t4$15 = $[4];
   }
 
-  return t5$15;
+  return t4$15;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/conditional-break.expect.md b/compiler/forget/src/__tests__/fixtures/hir/conditional-break.expect.md
index 408ec8b06f..43813732c8 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/conditional-break.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/conditional-break.expect.md
@@ -374,15 +374,13 @@ bb1:
 function Component(
   props,
 ) {
-  scope @0 [1:7] deps=[read props$3.a, read props$3.b, read props$3.d, read props$3.c] out=[] {
-    [1] Const mutate a$4_@0[1:7] = Array []
-    [2] Call mutate a$4_@0.push(read props$3.a)
-    if (read props$3.b) {
-      [6] Call mutate a$4_@0.push(read props$3.d)
-      return freeze a$4_@0
-    }
-    [4] Call mutate a$4_@0.push(read props$3.c)
+  [1] Const mutate a$4_@0[1:7] = Array []
+  [2] Call mutate a$4_@0.push(read props$3.a)
+  if (read props$3.b) {
+    [6] Call mutate a$4_@0.push(read props$3.d)
+    return freeze a$4_@0
   }
+  [4] Call mutate a$4_@0.push(read props$3.c)
 }
 
 ```
@@ -391,27 +389,14 @@ function Component(
 
 ```javascript
 function Component$0(props$3) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== props$3.a;
-  const c_1 = $[1] !== props$3.b;
-  const c_2 = $[2] !== props$3.d;
-  const c_3 = $[3] !== props$3.c;
-  if (c_0 || c_1 || c_2 || c_3) {
-    const a$4 = [];
-    a$4.push(props$3.a);
-
-    if (props$3.b) {
-      a$4.push(props$3.d);
-      return a$4;
-    }
-
-    a$4.push(props$3.c);
-    $[0] = props$3.a;
-    $[1] = props$3.b;
-    $[2] = props$3.d;
-    $[3] = props$3.c;
-  } else {
+  const a$4 = [];
+  a$4.push(props$3.a);
+  if (props$3.b) {
+    a$4.push(props$3.d);
+    return a$4;
   }
+
+  a$4.push(props$3.c);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/constructor.expect.md b/compiler/forget/src/__tests__/fixtures/hir/constructor.expect.md
index 4584a93f7e..e4e1bb0b7a 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/constructor.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/constructor.expect.md
@@ -49,8 +49,8 @@ bb0:
   [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
   [6] New mutate Foo$4(mutate b$11_@0:TObject)
   [7] Const mutate $14:TPrimitive = "div"
-  [8] Const mutate t5$15_@2 = JSX <read $14:TPrimitive a={read a$10_@0} b={freeze b$11_@0:TObject} ></read $14:TPrimitive>
-  [9] Return read t5$15_@2
+  [8] Const mutate t4$15_@2 = JSX <read $14:TPrimitive a={read a$10_@0} b={freeze b$11_@0:TObject} ></read $14:TPrimitive>
+  [9] Return read t4$15_@2
 ```
 
 ## Reactive Scopes
@@ -64,9 +64,7 @@ function Component(
     [2] Const mutate b$11_@0:TObject[1:7] = Object {  }
     [3] New mutate Foo$4(mutate a$10_@0, mutate b$11_@0:TObject)
     [4] Const mutate $12:TPrimitive = "div"
-    scope @1 [5:6] deps=[freeze a$10_@0] out=[] {
-      [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
-    }
+    [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
     [6] New mutate Foo$4(mutate b$11_@0:TObject)
   }
   [7] Const mutate $14:TPrimitive = "div"
@@ -85,18 +83,12 @@ function Component$0(props$9) {
   const $ = React.useMemoCache();
   let a$10;
   let b$11;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$10 = [];
     b$11 = {};
     new Foo$4(a$10, b$11);
-    const c_2 = $[2] !== a$10;
 
-    if (c_2) {
-      const _$13 = <div a={a$10}></div>;
-
-      $[2] = a$10;
-    } else {
-    }
+    const _$13 = <div a={a$10}></div>;
 
     new Foo$4(b$11);
     $[0] = a$10;
@@ -106,20 +98,20 @@ function Component$0(props$9) {
     b$11 = $[1];
   }
 
-  const c_3 = $[3] !== a$10;
-  const c_4 = $[4] !== b$11;
-  let t5$15;
+  const c_2 = $[2] !== a$10;
+  const c_3 = $[3] !== b$11;
+  let t4$15;
 
-  if (c_3 || c_4) {
-    t5$15 = <div a={a$10} b={b$11}></div>;
-    $[3] = a$10;
-    $[4] = b$11;
-    $[5] = t5$15;
+  if (c_2 || c_3) {
+    t4$15 = <div a={a$10} b={b$11}></div>;
+    $[2] = a$10;
+    $[3] = b$11;
+    $[4] = t4$15;
   } else {
-    t5$15 = $[5];
+    t4$15 = $[4];
   }
 
-  return t5$15;
+  return t4$15;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/dependencies-outputs.expect.md b/compiler/forget/src/__tests__/fixtures/hir/dependencies-outputs.expect.md
index 6a8fcd8bec..60a4daa58a 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/dependencies-outputs.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/dependencies-outputs.expect.md
@@ -57,14 +57,12 @@ function foo(
   }
   [3] Const mutate $9:TPrimitive = "div"
   [4] JSX <read $9:TPrimitive>{freeze x$8_@0}</read $9:TPrimitive>
-  scope @1 [5:12] deps=[read x$8_@0, read b$7] out=[] {
-    [5] Const mutate y$10_@1[5:12] = Array []
-    if (read x$8_@0.length) {
-      [7] Call mutate y$10_@1.push(read x$8_@0)
-    }
-    if (read b$7) {
-      [10] Call mutate y$10_@1.push(read b$7)
-    }
+  [5] Const mutate y$10_@1[5:12] = Array []
+  if (read x$8_@0.length) {
+    [7] Call mutate y$10_@1.push(read x$8_@0)
+  }
+  if (read b$7) {
+    [10] Call mutate y$10_@1.push(read b$7)
   }
   return
 }
@@ -88,23 +86,14 @@ function foo$0(a$6, b$7) {
   }
 
   <div>{x$8}</div>;
-  const c_2 = $[2] !== x$8;
-  const c_3 = $[3] !== b$7;
+  const y$10 = [];
 
-  if (c_2 || c_3) {
-    const y$10 = [];
+  if (x$8.length) {
+    y$10.push(x$8);
+  }
 
-    if (x$8.length) {
-      y$10.push(x$8);
-    }
-
-    if (b$7) {
-      y$10.push(b$7);
-    }
-
-    $[2] = x$8;
-    $[3] = b$7;
-  } else {
+  if (b$7) {
+    y$10.push(b$7);
   }
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/dependencies.expect.md b/compiler/forget/src/__tests__/fixtures/hir/dependencies.expect.md
index 08bfa271c2..dc440be7e6 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/dependencies.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/dependencies.expect.md
@@ -52,19 +52,17 @@ function foo(
   y,
   z,
 ) {
-  scope @0 [1:10] deps=[read z$8, read x$6, read y$7] out=[] {
-    [1] Const mutate items$9_@0[1:10] = Array [read z$8]
-    [2] Call mutate items$9_@0.push(read x$6)
-    scope @1 [3:7] deps=[read x$6, read y$7] out=[items2$10_@1] {
-      [3] Const mutate items2$10_@1[3:7] = Array []
-      if (read x$6) {
-        [5] Call mutate items2$10_@1.push(read y$7)
-      }
-    }
-    if (read y$7) {
-      [8] Call mutate items$9_@0.push(read x$6)
+  [1] Const mutate items$9_@0[1:10] = Array [read z$8]
+  [2] Call mutate items$9_@0.push(read x$6)
+  scope @1 [3:7] deps=[read x$6, read y$7] out=[items2$10_@1] {
+    [3] Const mutate items2$10_@1[3:7] = Array []
+    if (read x$6) {
+      [5] Call mutate items2$10_@1.push(read y$7)
     }
   }
+  if (read y$7) {
+    [8] Call mutate items$9_@0.push(read x$6)
+  }
   return freeze items2$10_@1
 }
 
@@ -75,38 +73,27 @@ function foo(
 ```javascript
 function foo$0(x$6, y$7, z$8) {
   const $ = React.useMemoCache();
-  const c_0 = $[0] !== z$8;
-  const c_1 = $[1] !== x$6;
-  const c_2 = $[2] !== y$7;
-  if (c_0 || c_1 || c_2) {
-    const items$9 = [z$8];
-    items$9.push(x$6);
-    const c_3 = $[3] !== x$6;
-    const c_4 = $[4] !== y$7;
-    let items2$10;
+  const items$9 = [z$8];
+  items$9.push(x$6);
+  const c_0 = $[0] !== x$6;
+  const c_1 = $[1] !== y$7;
+  let items2$10;
+  if (c_0 || c_1) {
+    items2$10 = [];
 
-    if (c_3 || c_4) {
-      items2$10 = [];
-
-      if (x$6) {
-        items2$10.push(y$7);
-      }
-
-      $[3] = x$6;
-      $[4] = y$7;
-      $[5] = items2$10;
-    } else {
-      items2$10 = $[5];
+    if (x$6) {
+      items2$10.push(y$7);
     }
 
-    if (y$7) {
-      items$9.push(x$6);
-    }
-
-    $[0] = z$8;
-    $[1] = x$6;
-    $[2] = y$7;
+    $[0] = x$6;
+    $[1] = y$7;
+    $[2] = items2$10;
   } else {
+    items2$10 = $[2];
+  }
+
+  if (y$7) {
+    items$9.push(x$6);
   }
 
   return items2$10;
diff --git a/compiler/forget/src/__tests__/fixtures/hir/extend-scopes-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/extend-scopes-if.expect.md
index c7f6eca50b..88247e997b 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/extend-scopes-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/extend-scopes-if.expect.md
@@ -56,14 +56,12 @@ function foo(
   b,
   c,
 ) {
-  scope @0 [1:8] deps=[read a$7, read b$8, read c$9] out=[] {
-    [1] Const mutate x$10_@0[1:8] = Array []
-    if (read a$7) {
-      if (read b$8) {
-        if (read c$9) {
-          [5] Const mutate $11:TPrimitive = 0
-          [6] Call mutate x$10_@0.push(read $11:TPrimitive)
-        }
+  [1] Const mutate x$10_@0[1:8] = Array []
+  if (read a$7) {
+    if (read b$8) {
+      if (read c$9) {
+        [5] Const mutate $11:TPrimitive = 0
+        [6] Call mutate x$10_@0.push(read $11:TPrimitive)
       }
     }
   }
@@ -80,25 +78,13 @@ function foo(
 
 ```javascript
 function foo$0(a$7, b$8, c$9) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== a$7;
-  const c_1 = $[1] !== b$8;
-  const c_2 = $[2] !== c$9;
-  if (c_0 || c_1 || c_2) {
-    const x$10 = [];
-
-    if (a$7) {
-      if (b$8) {
-        if (c$9) {
-          x$10.push(0);
-        }
+  const x$10 = [];
+  if (a$7) {
+    if (b$8) {
+      if (c$9) {
+        x$10.push(0);
       }
     }
-
-    $[0] = a$7;
-    $[1] = b$8;
-    $[2] = c$9;
-  } else {
   }
 
   if (a$7.length) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/frozen-after-alias.expect.md b/compiler/forget/src/__tests__/fixtures/hir/frozen-after-alias.expect.md
index 24358e3c87..59c100efcd 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/frozen-after-alias.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/frozen-after-alias.expect.md
@@ -47,7 +47,7 @@ function Component(
 function Component$0() {
   const $ = React.useMemoCache();
   let a$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$5 = [];
     $[0] = a$5;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/hook-call.expect.md b/compiler/forget/src/__tests__/fixtures/hir/hook-call.expect.md
index a1b5b6913b..a8538c0731 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/hook-call.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/hook-call.expect.md
@@ -109,7 +109,7 @@ function Component(
 function Component$0(props$10) {
   const $ = React.useMemoCache();
   let x$11;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$11 = [];
     $[0] = x$11;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-arguments.expect.md b/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-arguments.expect.md
index 7f823b29eb..e19cf748f1 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-arguments.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/hooks-freeze-arguments.expect.md
@@ -48,7 +48,7 @@ function Component(
 function Component$0() {
   const $ = React.useMemoCache();
   let a$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$4 = [];
     $[0] = a$4;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/inverted-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/inverted-if.expect.md
index acee1dbbae..668911db0e 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/inverted-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/inverted-if.expect.md
@@ -40,12 +40,10 @@ function foo(
   b,
   c,
 ) {
-  scope @0 [1:6] deps=[read a$5, read b$6, read c$7] out=[] {
-    [1] Const mutate y$8_@0[1:6] = Array []
-    if (read a$5) {
-      if (read b$6) {
-        [4] Call mutate y$8_@0.push(read c$7)
-      }
+  [1] Const mutate y$8_@0[1:6] = Array []
+  if (read a$5) {
+    if (read b$6) {
+      [4] Call mutate y$8_@0.push(read c$7)
     }
   }
   return
@@ -57,23 +55,11 @@ function foo(
 
 ```javascript
 function foo$0(a$5, b$6, c$7) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== a$5;
-  const c_1 = $[1] !== b$6;
-  const c_2 = $[2] !== c$7;
-  if (c_0 || c_1 || c_2) {
-    const y$8 = [];
-
-    if (a$5) {
-      if (b$6) {
-        y$8.push(c$7);
-      }
+  const y$8 = [];
+  if (a$5) {
+    if (b$6) {
+      y$8.push(c$7);
     }
-
-    $[0] = a$5;
-    $[1] = b$6;
-    $[2] = c$7;
-  } else {
   }
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/jsx-fragment.expect.md b/compiler/forget/src/__tests__/fixtures/hir/jsx-fragment.expect.md
index 3adea1d4f9..f8b024c0ee 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/jsx-fragment.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/jsx-fragment.expect.md
@@ -67,7 +67,7 @@ function Foo(
 function Foo$0(props$13) {
   const $ = React.useMemoCache();
   let t0$20;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0$20 = <>Text</>;
     $[0] = t0$20;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md b/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md
index 2a08c2b369..0c19c459ee 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/logical-expression.expect.md
@@ -66,7 +66,7 @@ function And(
 function And$0() {
   const $ = React.useMemoCache();
   let t0$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0$5 = f$1();
     $[0] = t0$5;
   } else {
@@ -142,7 +142,7 @@ function Or(
 function Or$0() {
   const $ = React.useMemoCache();
   let t0$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0$5 = f$1();
     $[0] = t0$5;
   } else {
@@ -223,7 +223,7 @@ function QuestionQuestion(
 function QuestionQuestion$0(props$8) {
   const $ = React.useMemoCache();
   let t0$9;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0$9 = f$2();
     $[0] = t0$9;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md
index 2ad5900810..6e53357704 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-loops.expect.md
@@ -139,37 +139,35 @@ bb13:
 function Component(
   props,
 ) {
-  scope @0 [1:23] deps=[] out=[] {
-    [1] Let mutate a$18_@0[1:23] = Object {  }
-    [2] Let mutate b$20_@0[1:23] = Object {  }
-    [3] Let mutate c$22_@0[1:23] = Object {  }
-    [4] Let mutate d$24_@0[1:23] = Object {  }
-    while (
-      [6] Const mutate $17:TPrimitive = true
-      read $17:TPrimitive
-    ) {
-      [8] Const mutate z$19_@0[1:23] = read a$18_@0
-      [9] Reassign mutate a$18_@0[1:23] = read b$20_@0
-      [10] Reassign mutate b$20_@0[1:23] = read c$22_@0
-      [11] Reassign mutate c$22_@0[1:23] = read d$24_@0
-      [12] Reassign mutate d$24_@0[1:23] = read z$19_@0
-      [13] Call mutate mutate$7:TFunction(mutate a$18_@0, mutate b$20_@0)
-      [14] Const mutate $29_@0[1:23] = Call mutate cond$8:TFunction(mutate a$18_@0)
-      if (read $29_@0) {
-        break
-      }
+  [1] Let mutate a$18_@0[1:23] = Object {  }
+  [2] Let mutate b$20_@0[1:23] = Object {  }
+  [3] Let mutate c$22_@0[1:23] = Object {  }
+  [4] Let mutate d$24_@0[1:23] = Object {  }
+  while (
+    [6] Const mutate $17:TPrimitive = true
+    read $17:TPrimitive
+  ) {
+    [8] Const mutate z$19_@0[1:23] = read a$18_@0
+    [9] Reassign mutate a$18_@0[1:23] = read b$20_@0
+    [10] Reassign mutate b$20_@0[1:23] = read c$22_@0
+    [11] Reassign mutate c$22_@0[1:23] = read d$24_@0
+    [12] Reassign mutate d$24_@0[1:23] = read z$19_@0
+    [13] Call mutate mutate$7:TFunction(mutate a$18_@0, mutate b$20_@0)
+    [14] Const mutate $29_@0[1:23] = Call mutate cond$8:TFunction(mutate a$18_@0)
+    if (read $29_@0) {
+      break
     }
-    if (read a$18_@0) {
-    }
-    if (read b$20_@0) {
-    }
-    if (read c$22_@0) {
-    }
-    if (read d$24_@0) {
-    }
-    [21] Const mutate $34:TPrimitive = null
-    [22] Call mutate mutate$7:TFunction(mutate d$24_@0, read $34:TPrimitive)
   }
+  if (read a$18_@0) {
+  }
+  if (read b$20_@0) {
+  }
+  if (read c$22_@0) {
+  }
+  if (read d$24_@0) {
+  }
+  [21] Const mutate $34:TPrimitive = null
+  [22] Call mutate mutate$7:TFunction(mutate d$24_@0, read $34:TPrimitive)
   return
 }
 
@@ -179,39 +177,36 @@ function Component(
 
 ```javascript
 function Component$0(props$12) {
-  if (true) {
-    let a$18 = {};
-    let b$20 = {};
-    let c$22 = {};
-    let d$24 = {};
-    while (true) {
-      const z$19 = a$18;
-      a$18 = b$20;
-      b$20 = c$22;
-      c$22 = d$24;
-      d$24 = z$19;
-      mutate$7(a$18, b$20);
+  let a$18 = {};
+  let b$20 = {};
+  let c$22 = {};
+  let d$24 = {};
+  while (true) {
+    const z$19 = a$18;
+    a$18 = b$20;
+    b$20 = c$22;
+    c$22 = d$24;
+    d$24 = z$19;
+    mutate$7(a$18, b$20);
 
-      if (cond$8(a$18)) {
-        break;
-      }
+    if (cond$8(a$18)) {
+      break;
     }
-
-    if (a$18) {
-    }
-
-    if (b$20) {
-    }
-
-    if (c$22) {
-    }
-
-    if (d$24) {
-    }
-
-    mutate$7(d$24, null);
-  } else {
   }
+
+  if (a$18) {
+  }
+
+  if (b$20) {
+  }
+
+  if (c$22) {
+  }
+
+  if (d$24) {
+  }
+
+  mutate$7(d$24, null);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md
index 11c5cb77f5..d5c3b4d32b 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/mutable-lifetime-with-aliasing.expect.md
@@ -100,28 +100,26 @@ function Component(
   scope @0 [1:2] deps=[] out=[a$11_@0] {
     [1] Const mutate a$11_@0:TObject = Object {  }
   }
-  scope @1 [2:15] deps=[read a$11_@0:TObject] out=[] {
-    [2] Const mutate b$12_@1[2:15] = Array [read a$11_@0:TObject]
-    scope @2 [3:4] deps=[] out=[c$13_@2] {
-      [3] Const mutate c$13_@2:TObject = Object {  }
-    }
-    [4] Const mutate d$14_@1:TObject[2:15] = Object { c: read c$13_@2:TObject }
-    [5] Const mutate x$15_@1:TObject[2:15] = Object {  }
-    [6] Reassign mutate x$15_@1.b[2:15] = read b$12_@1
-    [7] Const mutate y$16_@1[2:15] = Call mutate mutate$8:TFunction(mutate x$15_@1:TObject, mutate d$14_@1:TObject)
-    if (read a$11_@0:TObject) {
-    }
-    if (read b$12_@1) {
-    }
-    if (read c$13_@2:TObject) {
-    }
-    if (read d$14_@1:TObject) {
-    }
-    if (read y$16_@1) {
-    }
-    [13] Const mutate $17:TPrimitive = null
-    [14] Call mutate mutate$8:TFunction(mutate x$15_@1:TObject, read $17:TPrimitive)
+  [2] Const mutate b$12_@1[2:15] = Array [read a$11_@0:TObject]
+  scope @2 [3:4] deps=[] out=[c$13_@2] {
+    [3] Const mutate c$13_@2:TObject = Object {  }
   }
+  [4] Const mutate d$14_@1:TObject[2:15] = Object { c: read c$13_@2:TObject }
+  [5] Const mutate x$15_@1:TObject[2:15] = Object {  }
+  [6] Reassign mutate x$15_@1.b[2:15] = read b$12_@1
+  [7] Const mutate y$16_@1[2:15] = Call mutate mutate$8:TFunction(mutate x$15_@1:TObject, mutate d$14_@1:TObject)
+  if (read a$11_@0:TObject) {
+  }
+  if (read b$12_@1) {
+  }
+  if (read c$13_@2:TObject) {
+  }
+  if (read d$14_@1:TObject) {
+  }
+  if (read y$16_@1) {
+  }
+  [13] Const mutate $17:TPrimitive = null
+  [14] Call mutate mutate$8:TFunction(mutate x$15_@1:TObject, read $17:TPrimitive)
   return
 }
 
@@ -133,52 +131,46 @@ function Component(
 function Component$0(props$10) {
   const $ = React.useMemoCache();
   let a$11;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$11 = {};
     $[0] = a$11;
   } else {
     a$11 = $[0];
   }
 
-  const c_1 = $[1] !== a$11;
+  const b$12 = [a$11];
+  let c$13;
 
-  if (c_1) {
-    const b$12 = [a$11];
-    let c$13;
-
-    if (true) {
-      c$13 = {};
-      $[2] = c$13;
-    } else {
-      c$13 = $[2];
-    }
-
-    const d$14 = {
-      c: c$13,
-    };
-    const x$15 = {};
-    x$15.b = b$12;
-    const y$16 = mutate$8(x$15, d$14);
-
-    if (a$11) {
-    }
-
-    if (b$12) {
-    }
-
-    if (c$13) {
-    }
-
-    if (d$14) {
-    }
-
-    if (y$16) {
-    }
-
-    mutate$8(x$15, null);
-    $[1] = a$11;
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+    c$13 = {};
+    $[1] = c$13;
   } else {
+    c$13 = $[1];
   }
+
+  const d$14 = {
+    c: c$13,
+  };
+  const x$15 = {};
+  x$15.b = b$12;
+  const y$16 = mutate$8(x$15, d$14);
+
+  if (a$11) {
+  }
+
+  if (b$12) {
+  }
+
+  if (c$13) {
+  }
+
+  if (d$14) {
+  }
+
+  if (y$16) {
+  }
+
+  mutate$8(x$15, null);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/mutable-liverange-loop.expect.md b/compiler/forget/src/__tests__/fixtures/hir/mutable-liverange-loop.expect.md
index faf7606a5b..5a5f15346c 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/mutable-liverange-loop.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/mutable-liverange-loop.expect.md
@@ -126,34 +126,32 @@ bb13:
 function Component(
   props,
 ) {
-  scope @0 [1:18] deps=[] out=[] {
-    [1] Const mutate a$12_@0:TObject[1:18] = Object {  }
-    [2] Const mutate b$13_@0:TObject[1:18] = Object {  }
-    scope @1 [3:4] deps=[] out=[c$14_@1] {
-      [3] Const mutate c$14_@1:TObject = Object {  }
-    }
-    [4] Const mutate d$15_@0:TObject[1:18] = Object {  }
-    while (
-      [6] Const mutate $16:TPrimitive = true
-      read $16:TPrimitive
-    ) {
-      [8] Call mutate mutate$6:TFunction(mutate a$12_@0:TObject, mutate b$13_@0:TObject)
-      [9] Const mutate $21_@0[1:18] = Call mutate cond$7:TFunction(mutate a$12_@0:TObject)
-      if (read $21_@0) {
-        break
-      }
-    }
-    if (read a$12_@0:TObject) {
-    }
-    if (read b$13_@0:TObject) {
-    }
-    if (read c$14_@1:TObject) {
-    }
-    if (read d$15_@0:TObject) {
-    }
-    [16] Const mutate $28:TPrimitive = null
-    [17] Call mutate mutate$6:TFunction(mutate d$15_@0:TObject, read $28:TPrimitive)
+  [1] Const mutate a$12_@0:TObject[1:18] = Object {  }
+  [2] Const mutate b$13_@0:TObject[1:18] = Object {  }
+  scope @1 [3:4] deps=[] out=[c$14_@1] {
+    [3] Const mutate c$14_@1:TObject = Object {  }
   }
+  [4] Const mutate d$15_@0:TObject[1:18] = Object {  }
+  while (
+    [6] Const mutate $16:TPrimitive = true
+    read $16:TPrimitive
+  ) {
+    [8] Call mutate mutate$6:TFunction(mutate a$12_@0:TObject, mutate b$13_@0:TObject)
+    [9] Const mutate $21_@0[1:18] = Call mutate cond$7:TFunction(mutate a$12_@0:TObject)
+    if (read $21_@0) {
+      break
+    }
+  }
+  if (read a$12_@0:TObject) {
+  }
+  if (read b$13_@0:TObject) {
+  }
+  if (read c$14_@1:TObject) {
+  }
+  if (read d$15_@0:TObject) {
+  }
+  [16] Const mutate $28:TPrimitive = null
+  [17] Call mutate mutate$6:TFunction(mutate d$15_@0:TObject, read $28:TPrimitive)
   return
 }
 
@@ -164,43 +162,39 @@ function Component(
 ```javascript
 function Component$0(props$11) {
   const $ = React.useMemoCache();
-  if (true) {
-    const a$12 = {};
-    const b$13 = {};
-    let c$14;
-
-    if (true) {
-      c$14 = {};
-      $[0] = c$14;
-    } else {
-      c$14 = $[0];
-    }
-
-    const d$15 = {};
-
-    while (true) {
-      mutate$6(a$12, b$13);
-
-      if (cond$7(a$12)) {
-        break;
-      }
-    }
-
-    if (a$12) {
-    }
-
-    if (b$13) {
-    }
-
-    if (c$14) {
-    }
-
-    if (d$15) {
-    }
-
-    mutate$6(d$15, null);
+  const a$12 = {};
+  const b$13 = {};
+  let c$14;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    c$14 = {};
+    $[0] = c$14;
   } else {
+    c$14 = $[0];
   }
+
+  const d$15 = {};
+
+  while (true) {
+    mutate$6(a$12, b$13);
+
+    if (cond$7(a$12)) {
+      break;
+    }
+  }
+
+  if (a$12) {
+  }
+
+  if (b$13) {
+  }
+
+  if (c$14) {
+  }
+
+  if (d$15) {
+  }
+
+  mutate$6(d$15, null);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved-by-terminal.expect.md b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved-by-terminal.expect.md
index 0b8e7cc94f..17c229a6ad 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved-by-terminal.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved-by-terminal.expect.md
@@ -37,14 +37,12 @@ function foo(
   b,
   c,
 ) {
-  scope @0 [1:6] deps=[read a$6, read b$7] out=[] {
-    [1] Const mutate x$9_@0[1:6] = Array []
-    [2] Const mutate y$10_@0[1:6] = Array []
-    if (read x$9_@0) {
-    }
-    [4] Call mutate y$10_@0.push(read a$6)
-    [5] Call mutate x$9_@0.push(read b$7)
+  [1] Const mutate x$9_@0[1:6] = Array []
+  [2] Const mutate y$10_@0[1:6] = Array []
+  if (read x$9_@0) {
   }
+  [4] Call mutate y$10_@0.push(read a$6)
+  [5] Call mutate x$9_@0.push(read b$7)
   return
 }
 
@@ -54,22 +52,13 @@ function foo(
 
 ```javascript
 function foo$0(a$6, b$7, c$8) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== a$6;
-  const c_1 = $[1] !== b$7;
-  if (c_0 || c_1) {
-    const x$9 = [];
-    const y$10 = [];
-
-    if (x$9) {
-    }
-
-    y$10.push(a$6);
-    x$9.push(b$7);
-    $[0] = a$6;
-    $[1] = b$7;
-  } else {
+  const x$9 = [];
+  const y$10 = [];
+  if (x$9) {
   }
+
+  y$10.push(a$6);
+  x$9.push(b$7);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved.expect.md b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved.expect.md
index 036f6504cd..5d7e91787f 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-interleaved.expect.md
@@ -29,12 +29,10 @@ function foo(
   a,
   b,
 ) {
-  scope @0 [1:5] deps=[read a$5, read b$6] out=[] {
-    [1] Const mutate x$7_@0[1:5] = Array []
-    [2] Const mutate y$8_@0[1:5] = Array []
-    [3] Call mutate x$7_@0.push(read a$5)
-    [4] Call mutate y$8_@0.push(read b$6)
-  }
+  [1] Const mutate x$7_@0[1:5] = Array []
+  [2] Const mutate y$8_@0[1:5] = Array []
+  [3] Call mutate x$7_@0.push(read a$5)
+  [4] Call mutate y$8_@0.push(read b$6)
   return
 }
 
@@ -44,18 +42,10 @@ function foo(
 
 ```javascript
 function foo$0(a$5, b$6) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== a$5;
-  const c_1 = $[1] !== b$6;
-  if (c_0 || c_1) {
-    const x$7 = [];
-    const y$8 = [];
-    x$7.push(a$5);
-    y$8.push(b$6);
-    $[0] = a$5;
-    $[1] = b$6;
-  } else {
-  }
+  const x$7 = [];
+  const y$8 = [];
+  x$7.push(a$5);
+  y$8.push(b$6);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-shadowed.expect.md b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-shadowed.expect.md
index 9964de234d..e81d70c5ed 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-shadowed.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-shadowed.expect.md
@@ -29,14 +29,10 @@ function foo(
   a,
   b,
 ) {
-  scope @0 [1:5] deps=[read b$6, read a$5] out=[] {
-    [1] Const mutate x$7_@0[1:5] = Array []
-    scope @1 [2:4] deps=[read b$6] out=[] {
-      [2] Const mutate y$8_@1[2:4] = Array []
-      [3] Call mutate y$8_@1.push(read b$6)
-    }
-    [4] Call mutate x$7_@0.push(read a$5)
-  }
+  [1] Const mutate x$7_@0[1:5] = Array []
+  [2] Const mutate y$8_@1[2:4] = Array []
+  [3] Call mutate y$8_@1.push(read b$6)
+  [4] Call mutate x$7_@0.push(read a$5)
   return
 }
 
@@ -46,25 +42,10 @@ function foo(
 
 ```javascript
 function foo$0(a$5, b$6) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== b$6;
-  const c_1 = $[1] !== a$5;
-  if (c_0 || c_1) {
-    const x$7 = [];
-    const c_2 = $[2] !== b$6;
-
-    if (c_2) {
-      const y$8 = [];
-      y$8.push(b$6);
-      $[2] = b$6;
-    } else {
-    }
-
-    x$7.push(a$5);
-    $[0] = b$6;
-    $[1] = a$5;
-  } else {
-  }
+  const x$7 = [];
+  const y$8 = [];
+  y$8.push(b$6);
+  x$7.push(a$5);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-while.expect.md b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-while.expect.md
index 223fe2b9b1..d69d9df00c 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-while.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/overlapping-scopes-while.expect.md
@@ -41,15 +41,13 @@ function foo(
   b,
   c,
 ) {
-  scope @0 [1:8] deps=[read c$8, read b$7, read a$6] out=[] {
-    [1] Const mutate x$9_@0[1:8] = Array []
-    [2] Const mutate y$10_@0[1:8] = Array []
-    while (
-      read c$8
-    ) {
-      [5] Call mutate y$10_@0.push(read b$7)
-      [6] Call mutate x$9_@0.push(read a$6)
-    }
+  [1] Const mutate x$9_@0[1:8] = Array []
+  [2] Const mutate y$10_@0[1:8] = Array []
+  while (
+    read c$8
+  ) {
+    [5] Call mutate y$10_@0.push(read b$7)
+    [6] Call mutate x$9_@0.push(read a$6)
   }
   return
 }
@@ -60,23 +58,11 @@ function foo(
 
 ```javascript
 function foo$0(a$6, b$7, c$8) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== c$8;
-  const c_1 = $[1] !== b$7;
-  const c_2 = $[2] !== a$6;
-  if (c_0 || c_1 || c_2) {
-    const x$9 = [];
-    const y$10 = [];
-
-    while (c$8) {
-      y$10.push(b$7);
-      x$9.push(a$6);
-    }
-
-    $[0] = c$8;
-    $[1] = b$7;
-    $[2] = a$6;
-  } else {
+  const x$9 = [];
+  const y$10 = [];
+  while (c$8) {
+    y$10.push(b$7);
+    x$9.push(a$6);
   }
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/reactive-scope-grouping.expect.md b/compiler/forget/src/__tests__/fixtures/hir/reactive-scope-grouping.expect.md
index 0836998d40..5e8e225b2c 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/reactive-scope-grouping.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/reactive-scope-grouping.expect.md
@@ -51,11 +51,11 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$4 = {};
     let y$5;
 
-    if (true) {
+    if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
       y$5 = [];
       const z$6 = {};
       y$5.push(z$6);
diff --git a/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md b/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md
index 65bf827851..226453889a 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/reassignment-conditional.expect.md
@@ -35,8 +35,8 @@ bb1:
   predecessor blocks: bb2 bb0
   [7] Const mutate _$12_@1 = JSX <read Component$0 x={freeze x$7_@0} ></read Component$0>
   [8] Call read y$8.push(read props$6.p2)
-  [9] Const mutate t6$15_@2 = JSX <read Component$0 x={read x$7_@0} y={read y$8} ></read Component$0>
-  [10] Return read t6$15_@2
+  [9] Const mutate t5$15_@2 = JSX <read Component$0 x={read x$7_@0} y={read y$8} ></read Component$0>
+  [10] Return read t5$15_@2
 ```
 
 ## Reactive Scopes
@@ -53,9 +53,7 @@ function Component(
       [5] Reassign mutate x$7_@0[1:7] = Array []
     }
   }
-  scope @1 [7:8] deps=[freeze x$7_@0] out=[] {
-    [7] Const mutate _$12_@1 = JSX <read Component$0 x={freeze x$7_@0} ></read Component$0>
-  }
+  [7] Const mutate _$12_@1 = JSX <read Component$0 x={freeze x$7_@0} ></read Component$0>
   [8] Call read y$8.push(read props$6.p2)
   scope @2 [9:10] deps=[read x$7_@0, read y$8] out=[$15_@2] {
     [9] Const mutate $15_@2 = JSX <read Component$0 x={read x$7_@0} y={read y$8} ></read Component$0>
@@ -89,30 +87,23 @@ function Component$0(props$6) {
     x$7 = $[2];
   }
 
-  const c_3 = $[3] !== x$7;
-
-  if (c_3) {
-    const _$12 = <Component$0 x={x$7}></Component$0>;
-
-    $[3] = x$7;
-  } else {
-  }
+  const _$12 = <Component$0 x={x$7}></Component$0>;
 
   y$8.push(props$6.p2);
-  const c_4 = $[4] !== x$7;
-  const c_5 = $[5] !== y$8;
-  let t6$15;
+  const c_3 = $[3] !== x$7;
+  const c_4 = $[4] !== y$8;
+  let t5$15;
 
-  if (c_4 || c_5) {
-    t6$15 = <Component$0 x={x$7} y={y$8}></Component$0>;
-    $[4] = x$7;
-    $[5] = y$8;
-    $[6] = t6$15;
+  if (c_3 || c_4) {
+    t5$15 = <Component$0 x={x$7} y={y$8}></Component$0>;
+    $[3] = x$7;
+    $[4] = y$8;
+    $[5] = t5$15;
   } else {
-    t6$15 = $[6];
+    t5$15 = $[5];
   }
 
-  return t6$15;
+  return t5$15;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/reassignment.expect.md b/compiler/forget/src/__tests__/fixtures/hir/reassignment.expect.md
index 2ee1e0947c..d57c004ec9 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/reassignment.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/reassignment.expect.md
@@ -27,8 +27,8 @@ bb0:
   [4] Const mutate x$9_@1 = Array []
   [5] Const mutate _$10_@2 = JSX <read Component$0 x={freeze x$9_@1} ></read Component$0>
   [6] Call mutate y$8_@0.push(read props$6.p1)
-  [7] Const mutate t7$11_@3 = JSX <read Component$0 x={read x$9_@1} y={freeze y$8_@0} ></read Component$0>
-  [8] Return read t7$11_@3
+  [7] Const mutate t6$11_@3 = JSX <read Component$0 x={read x$9_@1} y={freeze y$8_@0} ></read Component$0>
+  [8] Return read t6$11_@3
 ```
 
 ## Reactive Scopes
@@ -44,9 +44,7 @@ function Component(
     scope @1 [4:5] deps=[] out=[x$9_@1] {
       [4] Const mutate x$9_@1 = Array []
     }
-    scope @2 [5:6] deps=[freeze x$9_@1] out=[] {
-      [5] Const mutate _$10_@2 = JSX <read Component$0 x={freeze x$9_@1} ></read Component$0>
-    }
+    [5] Const mutate _$10_@2 = JSX <read Component$0 x={freeze x$9_@1} ></read Component$0>
     [6] Call mutate y$8_@0.push(read props$6.p1)
   }
   scope @3 [7:8] deps=[read x$9_@1, freeze y$8_@0] out=[$11_@3] {
@@ -71,21 +69,14 @@ function Component$0(props$6) {
     y$8 = x$7;
     let x$9;
 
-    if (true) {
+    if ($[3] === Symbol.for("react.memo_cache_sentinel")) {
       x$9 = [];
       $[3] = x$9;
     } else {
       x$9 = $[3];
     }
 
-    const c_4 = $[4] !== x$9;
-
-    if (c_4) {
-      const _$10 = <Component$0 x={x$9}></Component$0>;
-
-      $[4] = x$9;
-    } else {
-    }
+    const _$10 = <Component$0 x={x$9}></Component$0>;
 
     y$8.push(props$6.p1);
     $[0] = props$6.p0;
@@ -95,20 +86,20 @@ function Component$0(props$6) {
     y$8 = $[2];
   }
 
-  const c_5 = $[5] !== x$9;
-  const c_6 = $[6] !== y$8;
-  let t7$11;
+  const c_4 = $[4] !== x$9;
+  const c_5 = $[5] !== y$8;
+  let t6$11;
 
-  if (c_5 || c_6) {
-    t7$11 = <Component$0 x={x$9} y={y$8}></Component$0>;
-    $[5] = x$9;
-    $[6] = y$8;
-    $[7] = t7$11;
+  if (c_4 || c_5) {
+    t6$11 = <Component$0 x={x$9} y={y$8}></Component$0>;
+    $[4] = x$9;
+    $[5] = y$8;
+    $[6] = t6$11;
   } else {
-    t7$11 = $[7];
+    t6$11 = $[6];
   }
 
-  return t7$11;
+  return t6$11;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/simple-alias.expect.md b/compiler/forget/src/__tests__/fixtures/hir/simple-alias.expect.md
index 29c4e6cc4f..ed88bc2df3 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/simple-alias.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/simple-alias.expect.md
@@ -58,9 +58,7 @@ bb0:
 ```
 function foo(
 ) {
-  scope @0 [1:2] deps=[] out=[] {
-    [1] Const mutate a$5_@0:TObject = Object {  }
-  }
+  [1] Const mutate a$5_@0:TObject = Object {  }
   scope @1 [2:8] deps=[] out=[c$10_@1] {
     [2] Const mutate b$6_@1:TObject[2:8] = Object {  }
     [3] Const mutate c$7_@1:TObject[2:8] = Object {  }
@@ -79,14 +77,9 @@ function foo(
 ```javascript
 function foo$0() {
   const $ = React.useMemoCache();
-  if (true) {
-    const a$5 = {};
-  } else {
-  }
-
+  const a$5 = {};
   let c$10;
-
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     const b$6 = {};
     const c$7 = {};
     const a$8 = b$6;
diff --git a/compiler/forget/src/__tests__/fixtures/hir/simple.expect.md b/compiler/forget/src/__tests__/fixtures/hir/simple.expect.md
index 40c4671785..a319cf386f 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/simple.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/simple.expect.md
@@ -75,7 +75,7 @@ function foo$0(x$8, y$9) {
 
   let t2$14;
 
-  if (true) {
+  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
     t2$14 = [y$9 * 10];
     $[2] = t2$14;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-arrayexpression.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-arrayexpression.expect.md
index 2087fab9df..737e69e017 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-arrayexpression.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-arrayexpression.expect.md
@@ -45,7 +45,7 @@ function Component$0(props$5) {
   const a$6 = 1;
   const b$7 = 2;
   let x$8;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$8 = [a$6, b$7];
     $[0] = x$8;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx-2.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx-2.expect.md
index bc29bd4296..dc0a28821c 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx-2.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx-2.expect.md
@@ -59,8 +59,8 @@ bb1:
   predecessor blocks: bb2 bb0
   [9] Call mutate foo$4:TFunction(read a$11_@0, mutate b$12_@0:TObject)
   [10] Const mutate $19:TPrimitive = "div"
-  [11] Const mutate t6$20_@3 = JSX <read $19:TPrimitive a={freeze a$11_@0} b={freeze b$12_@0:TObject} ></read $19:TPrimitive>
-  [12] Return read t6$20_@3
+  [11] Const mutate t5$20_@3 = JSX <read $19:TPrimitive a={freeze a$11_@0} b={freeze b$12_@0:TObject} ></read $19:TPrimitive>
+  [12] Return read t5$20_@3
 ```
 
 ## Reactive Scopes
@@ -78,9 +78,7 @@ function Component(
     }
     if (read $13_@1) {
       [6] Const mutate $14:TPrimitive = "div"
-      scope @2 [7:8] deps=[freeze a$11_@0] out=[] {
-        [7] Const mutate _$15_@2 = JSX <read $14:TPrimitive a={freeze a$11_@0} ></read $14:TPrimitive>
-      }
+      [7] Const mutate _$15_@2 = JSX <read $14:TPrimitive a={freeze a$11_@0} ></read $14:TPrimitive>
     }
     [9] Call mutate foo$4:TFunction(read a$11_@0, mutate b$12_@0:TObject)
   }
@@ -100,13 +98,13 @@ function Component$0(props$10) {
   const $ = React.useMemoCache();
   let a$11;
   let b$12;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$11 = [];
     b$12 = {};
     foo$4(a$11, b$12);
     let t2$13;
 
-    if (true) {
+    if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
       t2$13 = foo$4();
       $[2] = t2$13;
     } else {
@@ -114,14 +112,7 @@ function Component$0(props$10) {
     }
 
     if (t2$13) {
-      const c_3 = $[3] !== a$11;
-
-      if (c_3) {
-        const _$15 = <div a={a$11}></div>;
-
-        $[3] = a$11;
-      } else {
-      }
+      const _$15 = <div a={a$11}></div>;
     }
 
     foo$4(a$11, b$12);
@@ -132,20 +123,20 @@ function Component$0(props$10) {
     b$12 = $[1];
   }
 
-  const c_4 = $[4] !== a$11;
-  const c_5 = $[5] !== b$12;
-  let t6$20;
+  const c_3 = $[3] !== a$11;
+  const c_4 = $[4] !== b$12;
+  let t5$20;
 
-  if (c_4 || c_5) {
-    t6$20 = <div a={a$11} b={b$12}></div>;
-    $[4] = a$11;
-    $[5] = b$12;
-    $[6] = t6$20;
+  if (c_3 || c_4) {
+    t5$20 = <div a={a$11} b={b$12}></div>;
+    $[3] = a$11;
+    $[4] = b$12;
+    $[5] = t5$20;
   } else {
-    t6$20 = $[6];
+    t5$20 = $[5];
   }
 
-  return t6$20;
+  return t5$20;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx.expect.md
index ecaa45017c..00a9e96439 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-call-jsx.expect.md
@@ -49,8 +49,8 @@ bb0:
   [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
   [6] Call mutate foo$4:TFunction(read a$10_@0, mutate b$11_@0:TObject)
   [7] Const mutate $14:TPrimitive = "div"
-  [8] Const mutate t5$15_@2 = JSX <read $14:TPrimitive a={read a$10_@0} b={freeze b$11_@0:TObject} ></read $14:TPrimitive>
-  [9] Return read t5$15_@2
+  [8] Const mutate t4$15_@2 = JSX <read $14:TPrimitive a={read a$10_@0} b={freeze b$11_@0:TObject} ></read $14:TPrimitive>
+  [9] Return read t4$15_@2
 ```
 
 ## Reactive Scopes
@@ -64,9 +64,7 @@ function Component(
     [2] Const mutate b$11_@0:TObject[1:7] = Object {  }
     [3] Call mutate foo$4:TFunction(mutate a$10_@0, mutate b$11_@0:TObject)
     [4] Const mutate $12:TPrimitive = "div"
-    scope @1 [5:6] deps=[freeze a$10_@0] out=[] {
-      [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
-    }
+    [5] Const mutate _$13_@1 = JSX <read $12:TPrimitive a={freeze a$10_@0} ></read $12:TPrimitive>
     [6] Call mutate foo$4:TFunction(read a$10_@0, mutate b$11_@0:TObject)
   }
   [7] Const mutate $14:TPrimitive = "div"
@@ -85,18 +83,12 @@ function Component$0(props$9) {
   const $ = React.useMemoCache();
   let a$10;
   let b$11;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$10 = [];
     b$11 = {};
     foo$4(a$10, b$11);
-    const c_2 = $[2] !== a$10;
 
-    if (c_2) {
-      const _$13 = <div a={a$10}></div>;
-
-      $[2] = a$10;
-    } else {
-    }
+    const _$13 = <div a={a$10}></div>;
 
     foo$4(a$10, b$11);
     $[0] = a$10;
@@ -106,20 +98,20 @@ function Component$0(props$9) {
     b$11 = $[1];
   }
 
-  const c_3 = $[3] !== a$10;
-  const c_4 = $[4] !== b$11;
-  let t5$15;
+  const c_2 = $[2] !== a$10;
+  const c_3 = $[3] !== b$11;
+  let t4$15;
 
-  if (c_3 || c_4) {
-    t5$15 = <div a={a$10} b={b$11}></div>;
-    $[3] = a$10;
-    $[4] = b$11;
-    $[5] = t5$15;
+  if (c_2 || c_3) {
+    t4$15 = <div a={a$10} b={b$11}></div>;
+    $[2] = a$10;
+    $[3] = b$11;
+    $[4] = t4$15;
   } else {
-    t5$15 = $[5];
+    t4$15 = $[4];
   }
 
-  return t5$15;
+  return t4$15;
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md
index 96dd669d3b..2840d13e17 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-multiple-if.expect.md
@@ -76,7 +76,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$7;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$7 = 1;
     const y$8 = 2;
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md
index 0112c87c2e..6f1ef97d26 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-complex-single-if.expect.md
@@ -59,7 +59,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$5 = 1;
     const y$6 = 2;
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-for-of.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-for-of.expect.md
index 723714b463..212d9c28a5 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-for-of.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-for-of.expect.md
@@ -46,9 +46,7 @@ bb2:
 function foo(
   cond,
 ) {
-  scope @0 [1:2] deps=[] out=[] {
-    [1] Const mutate items$5_@0 = Array []
-  }
+  [1] Const mutate items$5_@0 = Array []
 }
 
 ```
@@ -57,10 +55,7 @@ function foo(
 
 ```javascript
 function foo$0(cond$4) {
-  if (true) {
-    const items$5 = [];
-  } else {
-  }
+  const items$5 = [];
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-for-trivial-update.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-for-trivial-update.expect.md
index 296d569752..5b0f7ea58d 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-for-trivial-update.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-for-trivial-update.expect.md
@@ -72,7 +72,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$6;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$6 = 1;
 
     for (const i$7 = 0; i$7 < 10; i$7) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md
index 6455540177..f33849d38d 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md
@@ -76,7 +76,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$7;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$7 = 1;
 
     for (let i$8 = 0; i$8 < 10; i$8 = i$8 + 1, i$8) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-nested-partial-phi.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-nested-partial-phi.expect.md
index 9f61e81e71..5831eb1b1d 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-nested-partial-phi.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-nested-partial-phi.expect.md
@@ -44,14 +44,12 @@ function foo(
   b,
   c,
 ) {
-  scope @0 [1:8] deps=[read a$5, read b$6, read c$7] out=[] {
-    [1] Const mutate x$8_@0[1:8] = read a$5
-    if (read b$6) {
-      if (read c$7) {
-        [4] Reassign mutate x$8_@0[1:8] = read c$7
-      }
-      [6] read x$8_@0
+  [1] Const mutate x$8_@0[1:8] = read a$5
+  if (read b$6) {
+    if (read c$7) {
+      [4] Reassign mutate x$8_@0[1:8] = read c$7
     }
+    [6] read x$8_@0
   }
   return
 }
@@ -62,25 +60,13 @@ function foo(
 
 ```javascript
 function foo$0(a$5, b$6, c$7) {
-  const $ = React.useMemoCache();
-  const c_0 = $[0] !== a$5;
-  const c_1 = $[1] !== b$6;
-  const c_2 = $[2] !== c$7;
-  if (c_0 || c_1 || c_2) {
-    const x$8 = a$5;
-
-    if (b$6) {
-      if (c$7) {
-        x$8 = c$7;
-      }
-
-      x$8;
+  const x$8 = a$5;
+  if (b$6) {
+    if (c$7) {
+      x$8 = c$7;
     }
 
-    $[0] = a$5;
-    $[1] = b$6;
-    $[2] = c$7;
-  } else {
+    x$8;
   }
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-newexpression.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-newexpression.expect.md
index 6d86df9188..8fc9c80d62 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-newexpression.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-newexpression.expect.md
@@ -68,7 +68,7 @@ function Component(
 function Component$0(props$6) {
   const $ = React.useMemoCache();
   let c$9;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     const a$7 = [];
     const b$8 = {};
     c$9 = new Foo$5(a$7, b$8);
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md
index 28b34ee5e4..4f9d05e8e8 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression-phi.expect.md
@@ -71,7 +71,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$6;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$6 = 1;
     let y$7 = 2;
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression.expect.md
index 6a8a976f3a..c1d66e099d 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-objectexpression.expect.md
@@ -45,7 +45,7 @@ function Component$0(props$5) {
   const a$6 = 1;
   const b$7 = 2;
   let x$8;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$8 = {
       a: a$6,
       b: b$7,
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-if.expect.md
index fff573da00..91677488f9 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-if.expect.md
@@ -75,7 +75,7 @@ function foo$0(a$5) {
     if (a$5) {
       let y$7;
 
-      if (true) {
+      if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
         y$7 = {};
         $[2] = y$7;
       } else {
@@ -86,7 +86,7 @@ function foo$0(a$5) {
     } else {
       let z$8;
 
-      if (true) {
+      if ($[3] === Symbol.for("react.memo_cache_sentinel")) {
         z$8 = {};
         $[3] = z$8;
       } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate-inside-if.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate-inside-if.expect.md
index a12459b363..f47e963968 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate-inside-if.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate-inside-if.expect.md
@@ -80,7 +80,7 @@ function foo$0(a$6) {
     } else {
       let z$9;
 
-      if (true) {
+      if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
         z$9 = {};
         $[2] = z$9;
       } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate.expect.md
index ee9d1062e3..b178687f5f 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-alias-mutate.expect.md
@@ -50,7 +50,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let y$7;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     const a$5 = {};
     const x$6 = a$5;
     y$7 = {};
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-call.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-call.expect.md
index c735c95d29..3c542a9fec 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-call.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-call.expect.md
@@ -46,7 +46,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$4 = [];
     $[0] = x$4;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-2.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-2.expect.md
index a3076dc2c2..4b80c3bdd3 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-2.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-2.expect.md
@@ -45,7 +45,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let y$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     const x$4 = [];
     y$5 = {};
     y$5.x = x$4;
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-alias.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-alias.expect.md
index ae2b61e49a..caf3562f38 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-alias.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate-alias.expect.md
@@ -50,7 +50,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let y$6;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     const a$5 = {};
     y$6 = a$5;
     const x$7 = [];
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate.expect.md
index 43c242a1bf..4495bced5a 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property-mutate.expect.md
@@ -45,7 +45,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let y$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     const x$4 = [];
     y$5 = {};
     y$5.x = x$4;
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md
index f3c7564413..7cd141438a 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-property.expect.md
@@ -44,7 +44,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$3;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$3 = [];
     $[0] = x$3;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md
index b051310aef..22edeb277e 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-return.expect.md
@@ -54,7 +54,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$4 = 1;
 
     if (x$4 === 1) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md
index 4f3648a606..70a20404e0 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-simple-phi.expect.md
@@ -68,7 +68,7 @@ function foo$0() {
   const $ = React.useMemoCache();
   const y$5 = 2;
   let y$8;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     y$8 = undefined;
 
     if (y$5 > 1) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md
index e7fbc0e184..16ad0a7c29 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-switch.expect.md
@@ -102,7 +102,7 @@ function foo$0() {
   const $ = React.useMemoCache();
   const x$10 = 1;
   let x$16;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$16 = undefined;
 
     bb1: switch (x$10) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md
index 74daa3b3b4..298fd2c7c1 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-throw.expect.md
@@ -53,7 +53,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$4 = 1;
 
     if (x$4 === 1) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md b/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md
index 7ca584a42b..64f04e3ee5 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/ssa-while.expect.md
@@ -61,7 +61,7 @@ function foo(
 function foo$0() {
   const $ = React.useMemoCache();
   let x$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$5 = 1;
 
     while (x$5 < 10) {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md b/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md
index f48373744c..6a516076f7 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/switch.expect.md
@@ -69,9 +69,7 @@ function Component(
       case read $12:TPrimitive: {
           [6] Call mutate x$9_@1.push(read props$8.p2)
           [7] Call mutate x$9_@1.push(read props$8.p3)
-          scope @2 [8:9] deps=[] out=[] {
-            [8] Const mutate y$13_@2 = Array []
-          }
+          [8] Const mutate y$13_@2 = Array []
       }
       case read $11:TPrimitive: {
           [10] Reassign mutate y$10_@1:TPrimitive[1:12] = read x$9_@1
@@ -107,11 +105,7 @@ function Component$0(props$8) {
       case true: {
         x$9.push(props$8.p2);
         x$9.push(props$8.p3);
-
-        if (true) {
-          const y$13 = [];
-        } else {
-        }
+        const y$13 = [];
       }
 
       case false: {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/transitive-alias-fields.expect.md b/compiler/forget/src/__tests__/fixtures/hir/transitive-alias-fields.expect.md
index 0778a152a9..d82370f934 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/transitive-alias-fields.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/transitive-alias-fields.expect.md
@@ -37,16 +37,14 @@ bb0:
 ```
 function component(
 ) {
-  scope @0 [1:9] deps=[] out=[] {
-    [1] Const mutate x$6_@0:TObject[1:9] = Object {  }
-    [2] Const mutate p$7_@0:TObject[1:9] = Object {  }
-    [3] Const mutate q$8_@0:TObject[1:9] = Object {  }
-    [4] Const mutate y$9_@0:TObject[1:9] = Object {  }
-    [5] Reassign mutate x$6_@0.y[1:9] = read y$9_@0:TObject
-    [6] Reassign mutate p$7_@0.y[1:9] = read x$6_@0.y
-    [7] Reassign mutate q$8_@0.y[1:9] = read p$7_@0.y
-    [8] Call mutate mutate$5:TFunction(mutate q$8_@0:TObject)
-  }
+  [1] Const mutate x$6_@0:TObject[1:9] = Object {  }
+  [2] Const mutate p$7_@0:TObject[1:9] = Object {  }
+  [3] Const mutate q$8_@0:TObject[1:9] = Object {  }
+  [4] Const mutate y$9_@0:TObject[1:9] = Object {  }
+  [5] Reassign mutate x$6_@0.y[1:9] = read y$9_@0:TObject
+  [6] Reassign mutate p$7_@0.y[1:9] = read x$6_@0.y
+  [7] Reassign mutate q$8_@0.y[1:9] = read p$7_@0.y
+  [8] Call mutate mutate$5:TFunction(mutate q$8_@0:TObject)
   return
 }
 
@@ -56,17 +54,14 @@ function component(
 
 ```javascript
 function component$0() {
-  if (true) {
-    const x$6 = {};
-    const p$7 = {};
-    const q$8 = {};
-    const y$9 = {};
-    x$6.y = y$9;
-    p$7.y = x$6.y;
-    q$8.y = p$7.y;
-    mutate$5(q$8);
-  } else {
-  }
+  const x$6 = {};
+  const p$7 = {};
+  const q$8 = {};
+  const y$9 = {};
+  x$6.y = y$9;
+  p$7.y = x$6.y;
+  q$8.y = p$7.y;
+  mutate$5(q$8);
 }
 
 ```
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-args-test-binary-operator.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-args-test-binary-operator.expect.md
index 12c1195d6c..5828952e8c 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-args-test-binary-operator.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-args-test-binary-operator.expect.md
@@ -34,9 +34,7 @@ function component(
 ) {
   [1] Const mutate $7:TPrimitive = Binary read a$5:TPrimitive > read b$6:TPrimitive
   if (read $7:TPrimitive) {
-    scope @0 [3:4] deps=[] out=[] {
-      [3] Const mutate m$8_@0:TObject = Object {  }
-    }
+    [3] Const mutate m$8_@0:TObject = Object {  }
   }
   return
 }
@@ -48,10 +46,7 @@ function component(
 ```javascript
 function component$0(a$5, b$6) {
   if (a$5 > b$6) {
-    if (true) {
-      const m$8 = {};
-    } else {
-    }
+    const m$8 = {};
   }
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-binary-operator.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-binary-operator.expect.md
index b7cdd51d5e..e209113e31 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-binary-operator.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-binary-operator.expect.md
@@ -42,9 +42,7 @@ function component(
   }
   [3] Const mutate $9:TPrimitive = Binary read a$7_@0:TPrimitive > read b$8_@1:TPrimitive
   if (read $9:TPrimitive) {
-    scope @2 [5:6] deps=[] out=[] {
-      [5] Const mutate m$10_@2:TObject = Object {  }
-    }
+    [5] Const mutate m$10_@2:TObject = Object {  }
   }
   return
 }
@@ -57,7 +55,7 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let a$7;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     a$7 = some$2();
     $[0] = a$7;
   } else {
@@ -66,7 +64,7 @@ function component$0() {
 
   let b$8;
 
-  if (true) {
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
     b$8 = someOther$4();
     $[1] = b$8;
   } else {
@@ -74,10 +72,7 @@ function component$0() {
   }
 
   if (a$7 > b$8) {
-    if (true) {
-      const m$10 = {};
-    } else {
-    }
+    const m$10 = {};
   }
 }
 
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-field-load.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-field-load.expect.md
index 297abfb7f5..0f06c4868f 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-field-load.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-field-load.expect.md
@@ -40,7 +40,7 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let x$5;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$5 = {
       t: 1,
     };
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-test-field-load-binary-op.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-test-field-load-binary-op.expect.md
index 2ddc19a314..e3d43d61e9 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-test-field-load-binary-op.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-test-field-load-binary-op.expect.md
@@ -65,7 +65,7 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let t0$10;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0$10 = makeSomePrimitive$2();
     $[0] = t0$10;
   } else {
@@ -74,7 +74,7 @@ function component$0() {
 
   let t1$11;
 
-  if (true) {
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
     t1$11 = makeSomePrimitive$2();
     $[1] = t1$11;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-test-field-store.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-test-field-store.expect.md
index 828dec3456..3d95311bd0 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-test-field-store.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-test-field-store.expect.md
@@ -46,11 +46,11 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let x$4;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$4 = {};
     let q$5;
 
-    if (true) {
+    if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
       q$5 = {};
       $[1] = q$5;
     } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-test-polymorphic.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-test-polymorphic.expect.md
index 0a3718cd4d..52fcdd7014 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-test-polymorphic.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-test-polymorphic.expect.md
@@ -63,7 +63,7 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let p$7;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     p$7 = makePrimitive$2();
     $[0] = p$7;
   } else {
@@ -73,7 +73,7 @@ function component$0() {
   p$7 + p$7;
   let o$8;
 
-  if (true) {
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
     o$8 = {};
     $[1] = o$8;
   } else {
diff --git a/compiler/forget/src/__tests__/fixtures/hir/type-test-return-type-inference.expect.md b/compiler/forget/src/__tests__/fixtures/hir/type-test-return-type-inference.expect.md
index 54b928b15e..6a65fc3b1d 100644
--- a/compiler/forget/src/__tests__/fixtures/hir/type-test-return-type-inference.expect.md
+++ b/compiler/forget/src/__tests__/fixtures/hir/type-test-return-type-inference.expect.md
@@ -45,13 +45,9 @@ function component(
   }
   [3] Const mutate $9:TPrimitive = Binary read x$7_@0:TPrimitive > read y$8_@1:TPrimitive
   if (read $9:TPrimitive) {
-    scope @2 [5:6] deps=[] out=[] {
-      [5] Const mutate z$10_@2:TObject = Object {  }
-    }
-  }
-  scope @3 [7:8] deps=[] out=[] {
-    [7] Const mutate z$12_@3 = Call mutate foo$2:TFunction()
+    [5] Const mutate z$10_@2:TObject = Object {  }
   }
+  [7] Const mutate z$12_@3 = Call mutate foo$2:TFunction()
   return
 }
 
@@ -63,7 +59,7 @@ function component(
 function component$0() {
   const $ = React.useMemoCache();
   let x$7;
-  if (true) {
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     x$7 = foo$2();
     $[0] = x$7;
   } else {
@@ -72,7 +68,7 @@ function component$0() {
 
   let y$8;
 
-  if (true) {
+  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
     y$8 = foo$2();
     $[1] = y$8;
   } else {
@@ -80,16 +76,10 @@ function component$0() {
   }
 
   if (x$7 > y$8) {
-    if (true) {
-      const z$10 = {};
-    } else {
-    }
+    const z$10 = {};
   }
 
-  if (true) {
-    const z$12 = foo$2();
-  } else {
-  }
+  const z$12 = foo$2();
 }
 
 ```