[compiler] Cleanup for @enablePreserveExistingMemoizationGuarantees (#34346)

I tried turning on `@enablePreserveExistingMemoizationGuarantees` by
default and cleaned up a couple small things:

* We emit freeze calls for StartMemoize deps but these had
ValueReason.Other so the message wasn't great. We now treat these like
other hook arguments.
* PruneNonEscapingScopes was being too aggressive in this mode and
memoizing even loads of globals. Switching to
MemoizationLevel.Conditional ensures we build a graph that connects
through to primitive-returning function calls, but doesn't unnecessarily
force memoization otherwise.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34346).
* #34347
* __->__ #34346

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

@@ -2089,7 +2089,7 @@ function computeSignatureForInstruction(
           effects.push({
             kind: 'Freeze',
             value: operand,
-            reason: ValueReason.Other,
+            reason: ValueReason.HookCaptured,
           });
         }
       }

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

@@ -546,7 +546,7 @@ class CollectDependenciesVisitor extends ReactiveFunctionVisitor<
            * memoization. Note: we may still prune primitive-producing scopes if
            * they don't ultimately escape at all.
            */
-          const level = MemoizationLevel.Memoized;
+          const level = MemoizationLevel.Conditional;
           return {
             lvalues: lvalue !== null ? [{place: lvalue, level}] : [],
             rvalues: [...eachReactiveValueOperand(value)],
@@ -701,9 +701,7 @@ class CollectDependenciesVisitor extends ReactiveFunctionVisitor<
       }
       case 'ComputedLoad':
       case 'PropertyLoad': {
-        const level = options.forceMemoizePrimitives
-          ? MemoizationLevel.Memoized
-          : MemoizationLevel.Conditional;
+        const level = MemoizationLevel.Conditional;
         return {
           // Indirection for the inner value, memoized if the value is
           lvalues: lvalue !== null ? [{place: lvalue, level}] : [],

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/meta-isms/repro-cx-namespace-nesting.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @compilationMode:"infer"
 import {makeArray} from 'shared-runtime';
 
 function Component() {
@@ -30,7 +31,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @compilationMode:"infer"
 import { makeArray } from "shared-runtime";
 
 function Component() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/meta-isms/repro-cx-namespace-nesting.js

@@ -1,3 +1,4 @@
+// @compilationMode:"infer"
 import {makeArray} from 'shared-runtime';
 
 function Component() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-existing-memoization-guarantees/lambda-with-fbt-preserve-memoization.expect.md

@@ -0,0 +1,86 @@
+
+## Input
+
+```javascript
+// @enablePreserveExistingMemoizationGuarantees
+import {fbt} from 'fbt';
+
+function Component() {
+  const buttonLabel = () => {
+    if (!someCondition) {
+      return <fbt desc="My label">{'Purchase as a gift'}</fbt>;
+    } else if (
+      !iconOnly &&
+      showPrice &&
+      item?.current_gift_offer?.price?.formatted != null
+    ) {
+      return (
+        <fbt desc="Gift button's label">
+          {'Gift | '}
+          <fbt:param name="price">
+            {item?.current_gift_offer?.price?.formatted}
+          </fbt:param>
+        </fbt>
+      );
+    } else if (!iconOnly && !showPrice) {
+      return <fbt desc="Gift button's label">{'Gift'}</fbt>;
+    }
+  };
+
+  return (
+    <View>
+      <Button text={buttonLabel()} />
+    </View>
+  );
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees
+import { fbt } from "fbt";
+
+function Component() {
+  const $ = _c(1);
+  const buttonLabel = _temp;
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (
+      <View>
+        <Button text={buttonLabel()} />
+      </View>
+    );
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+function _temp() {
+  if (!someCondition) {
+    return fbt._("Purchase as a gift", null, { hk: "1gHj4g" });
+  } else {
+    if (
+      !iconOnly &&
+      showPrice &&
+      item?.current_gift_offer?.price?.formatted != null
+    ) {
+      return fbt._(
+        "Gift | {price}",
+        [fbt._param("price", item?.current_gift_offer?.price?.formatted)],
+        { hk: "3GTnGE" },
+      );
+    } else {
+      if (!iconOnly && !showPrice) {
+        return fbt._("Gift", null, { hk: "3fqfrk" });
+      }
+    }
+  }
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-existing-memoization-guarantees/lambda-with-fbt-preserve-memoization.js

@@ -0,0 +1,31 @@
+// @enablePreserveExistingMemoizationGuarantees
+import {fbt} from 'fbt';
+
+function Component() {
+  const buttonLabel = () => {
+    if (!someCondition) {
+      return <fbt desc="My label">{'Purchase as a gift'}</fbt>;
+    } else if (
+      !iconOnly &&
+      showPrice &&
+      item?.current_gift_offer?.price?.formatted != null
+    ) {
+      return (
+        <fbt desc="Gift button's label">
+          {'Gift | '}
+          <fbt:param name="price">
+            {item?.current_gift_offer?.price?.formatted}
+          </fbt:param>
+        </fbt>
+      );
+    } else if (!iconOnly && !showPrice) {
+      return <fbt desc="Gift button's label">{'Gift'}</fbt>;
+    }
+  };
+
+  return (
+    <View>
+      <Button text={buttonLabel()} />
+    </View>
+  );
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/primitive-reassigned-loop-force-scopes-enabled.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @enableForest
+// @enablePreserveExistingMemoizationGuarantees
 function Component({base, start, increment, test}) {
   let value = base;
   for (let i = start; i < test; i += increment) {
@@ -27,25 +27,23 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableForest
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees
 function Component(t0) {
-  const $ = _c(5);
+  const $ = _c(2);
   const { base, start, increment, test } = t0;
-  let value;
-  if ($[0] !== base || $[1] !== increment || $[2] !== start || $[3] !== test) {
-    value = base;
-    for (let i = start; i < test; i = i + increment, i) {
-      value = value + i;
-    }
-    $[0] = base;
-    $[1] = increment;
-    $[2] = start;
-    $[3] = test;
-    $[4] = value;
-  } else {
-    value = $[4];
+  let value = base;
+  for (let i = start; i < test; i = i + increment, i) {
+    value = value + i;
   }
-  return <div>{value}</div>;
+  let t1;
+  if ($[0] !== value) {
+    t1 = <div>{value}</div>;
+    $[0] = value;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  return t1;
 }
 
 export const FIXTURE_ENTRYPOINT = {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/primitive-reassigned-loop-force-scopes-enabled.js

@@ -1,4 +1,4 @@
-// @enableForest
+// @enablePreserveExistingMemoizationGuarantees
 function Component({base, start, increment, test}) {
   let value = base;
   for (let i = start; i < test; i += increment) {