Dont memoize calls that produce primitive values

Teaches InferReactiveScopeVariables that calls can produce primitives that don't 
need a scope.

compiler/forget/src/Inference/InferReferenceEffects.ts

@@ -1013,7 +1013,7 @@ function hasContextRefOperand(
   return false;
 }
 
-function getFunctionCallSignature(
+export function getFunctionCallSignature(
   env: Environment,
   type: Type
 ): FunctionSignature | null {

compiler/forget/src/ReactiveScopes/InferReactiveScopeVariables.ts

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import { Environment } from "../HIR";
 import {
   HIRFunction,
   Identifier,
@@ -20,6 +21,7 @@ import {
   eachInstructionOperand,
   eachPatternOperand,
 } from "../HIR/visitors";
+import { getFunctionCallSignature } from "../Inference/InferReferenceEffects";
 import DisjointSet from "../Utils/DisjointSet";
 import { assertExhaustive } from "../Utils/utils";
 
@@ -103,7 +105,7 @@ export function inferReactiveScopeVariables(fn: HIRFunction): void {
     for (const instr of block.instructions) {
       const operands: Array<Identifier> = [];
       const range = instr.lvalue.identifier.mutableRange;
-      if (range.end > range.start + 1 || mayAllocate(instr.value)) {
+      if (range.end > range.start + 1 || mayAllocate(fn.env, instr.value)) {
         operands.push(instr.lvalue!.identifier);
       }
       if (
@@ -217,7 +219,7 @@ function isMutable({ id }: Instruction, place: Place): boolean {
   return id >= range.start && id < range.end;
 }
 
-function mayAllocate(value: InstructionValue): boolean {
+function mayAllocate(env: Environment, value: InstructionValue): boolean {
   switch (value.kind) {
     case "Destructure": {
       return doesPatternContainSpreadElement(value.lvalue.pattern);
@@ -245,12 +247,30 @@ function mayAllocate(value: InstructionValue): boolean {
     case "Debugger": {
       return false;
     }
+    case "CallExpression": {
+      const signature = getFunctionCallSignature(
+        env,
+        value.callee.identifier.type
+      );
+      if (signature !== null) {
+        return signature.returnType.kind !== "Primitive";
+      }
+      return true;
+    }
+    case "MethodCall": {
+      const signature = getFunctionCallSignature(
+        env,
+        value.receiver.identifier.type
+      );
+      if (signature !== null) {
+        return signature.returnType.kind !== "Primitive";
+      }
+      return true;
+    }
     case "RegExpLiteral":
-    case "MethodCall":
     case "PropertyStore":
     case "ComputedStore":
     case "ArrayExpression":
-    case "CallExpression":
     case "JsxExpression":
     case "JsxFragment":
     case "NewExpression":

compiler/forget/src/__tests__/fixtures/compiler/globals-Boolean.expect.md

@@ -15,7 +15,7 @@ function Component(props) {
 ```javascript
 import { unstable_useMemoCache as useMemoCache } from "react";
 function Component(props) {
-  const $ = useMemoCache(3);
+  const $ = useMemoCache(2);
   let t0;
   if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0 = {};
@@ -24,22 +24,15 @@ function Component(props) {
     t0 = $[0];
   }
   const x = t0;
+  const y = Boolean(x);
   let t1;
   if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
-    t1 = Boolean(x);
+    t1 = [x, y];
     $[1] = t1;
   } else {
     t1 = $[1];
   }
-  const y = t1;
-  let t2;
-  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
-    t2 = [x, y];
-    $[2] = t2;
-  } else {
-    t2 = $[2];
-  }
-  return t2;
+  return t1;
 }
 
 ```

compiler/forget/src/__tests__/fixtures/compiler/globals-Number.expect.md

@@ -15,7 +15,7 @@ function Component(props) {
 ```javascript
 import { unstable_useMemoCache as useMemoCache } from "react";
 function Component(props) {
-  const $ = useMemoCache(3);
+  const $ = useMemoCache(2);
   let t0;
   if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0 = {};
@@ -24,22 +24,15 @@ function Component(props) {
     t0 = $[0];
   }
   const x = t0;
+  const y = Number(x);
   let t1;
   if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
-    t1 = Number(x);
+    t1 = [x, y];
     $[1] = t1;
   } else {
     t1 = $[1];
   }
-  const y = t1;
-  let t2;
-  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
-    t2 = [x, y];
-    $[2] = t2;
-  } else {
-    t2 = $[2];
-  }
-  return t2;
+  return t1;
 }
 
 ```

compiler/forget/src/__tests__/fixtures/compiler/globals-String.expect.md

@@ -15,7 +15,7 @@ function Component(props) {
 ```javascript
 import { unstable_useMemoCache as useMemoCache } from "react";
 function Component(props) {
-  const $ = useMemoCache(3);
+  const $ = useMemoCache(2);
   let t0;
   if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
     t0 = {};
@@ -24,22 +24,15 @@ function Component(props) {
     t0 = $[0];
   }
   const x = t0;
+  const y = String(x);
   let t1;
   if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
-    t1 = String(x);
+    t1 = [x, y];
     $[1] = t1;
   } else {
     t1 = $[1];
   }
-  const y = t1;
-  let t2;
-  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
-    t2 = [x, y];
-    $[2] = t2;
-  } else {
-    t2 = $[2];
-  }
-  return t2;
+  return t1;
 }
 
 ```