Unify logic for checking for intrinsic objects that have been derived (#2581)

Summary:
Release notes: none

This PR cleans up some of the `onArrayWithWidenedNumericProperty` logic, making it more generic for cases where we want to use concrete derived object values. Furthermore, it strengthens the validation process by checking for existence of `isScopedTemplate` on the internal object.
Pull Request resolved: https://github.com/facebook/prepack/pull/2581

Differential Revision: D10141954

Pulled By: trueadm

fbshipit-source-id: 8de828080b8a41357830cdbf7e49359512bc7244

src/intrinsics/ecma262/JSON.js

@@ -305,7 +305,7 @@ function InternalCloneObject(realm: Realm, val: ObjectValue): ObjectValue {
   }
   if (val.isPartialObject()) clone.makePartial();
   if (val.isSimpleObject()) clone.makeSimple();
-  clone._isScopedTemplate = true; // because this object doesn't exist ahead of time, and the visitor would otherwise declare it in the common scope
+  clone.isScopedTemplate = true; // because this object doesn't exist ahead of time, and the visitor would otherwise declare it in the common scope
   return clone;
 }
 

src/serializer/Emitter.js

@@ -11,7 +11,6 @@
 
 import {
   AbstractValue,
-  ArrayValue,
   BoundFunctionValue,
   FunctionValue,
   ObjectValue,
@@ -38,9 +37,9 @@ type EmitterDependenciesVisitorCallbacks<T> = {
   // Callback invoked whenever a dependency is visited that is an abstract value with an identifier.
   // A return value that is not undefined indicates that the visitor should stop, and return the value as the overall result.
   onAbstractValueWithIdentifier?: AbstractValue => void | T,
-  // Callback invoked whenever a dependency is visited that is an array value with a widened numeric property.
+  // Callback invoked whenever a dependency is visited that is an intrinsic object that was derived
   // A return value that is not undefined indicates that the visitor should stop, and return the value as the overall result.
-  onArrayWithWidenedNumericProperty?: ArrayValue => void | T,
+  onIntrinsicDerivedObject?: ObjectValue => void | T,
 };
 
 // The emitter keeps track of a stack of what's currently being emitted.
@@ -78,7 +77,7 @@ export class Emitter {
     this._activeValues = new Set();
     this._activeGeneratorStack = [this._mainBody];
     this._finalized = false;
-    let mustWaitForValue = (val: AbstractValue | ArrayValue) => {
+    let mustWaitForValue = (val: AbstractValue | ObjectValue) => {
       if (this.cannotDeclare()) return false;
       if (this.hasBeenDeclared(val)) return false;
       let activeOptimizedFunction = this.getActiveOptimizedFunction();
@@ -95,7 +94,7 @@ export class Emitter {
       },
       onAbstractValueWithIdentifier: val =>
         derivedIds.has(val.getIdentifier()) && mustWaitForValue(val) ? val : undefined,
-      onArrayWithWidenedNumericProperty: val => (mustWaitForValue(val) ? val : undefined),
+      onIntrinsicDerivedObject: val => (mustWaitForValue(val) ? val : undefined),
     };
     this._conditionalFeasibility = conditionalFeasibility;
   }
@@ -351,10 +350,8 @@ export class Emitter {
         result = recurse(val.$Description);
         if (result !== undefined) return result;
       }
-    } else if (val instanceof ArrayValue && ArrayValue.isIntrinsicAndHasWidenedNumericProperty(val)) {
+    } else if (val instanceof ObjectValue && ObjectValue.isIntrinsicDerivedObject(val)) {
-      result = callbacks.onArrayWithWidenedNumericProperty
+      result = callbacks.onIntrinsicDerivedObject ? callbacks.onIntrinsicDerivedObject(val) : undefined;
-        ? callbacks.onArrayWithWidenedNumericProperty(val)
-        : undefined;
       if (result !== undefined) return result;
     } else if (val instanceof ObjectValue) {
       let kind = val.getKind();

src/serializer/ResidualHeapSerializer.js

@@ -940,11 +940,9 @@ export class ResidualHeapSerializer {
     // which is related to one of the scopes this value is used by.
     let notYetDoneBodies = new Set();
     this.emitter.dependenciesVisitor(val, {
-      onArrayWithWidenedNumericProperty: dependency => {
+      onIntrinsicDerivedObject: dependency => {
         if (trace) {
-          console.log(
+          console.log(`  depending on intrinsic derived object and an identifier ${dependency.intrinsicName || "?"}`);
-            `  depending on array with widened numeric properties and an identifier ${dependency.intrinsicName || "?"}`
-          );
         }
         invariant(
           optimizedFunctionRoot === undefined || !!this.emitter.getActiveOptimizedFunction(),

src/serializer/ResidualHeapVisitor.js

@@ -1087,7 +1087,7 @@ export class ResidualHeapVisitor {
     } else if (val.isIntrinsic()) {
       // All intrinsic values exist from the beginning of time...
       // ...except for a few that come into existence as templates for abstract objects via executable code.
-      if (val instanceof ObjectValue && val._isScopedTemplate) {
+      if (val instanceof ObjectValue && val.isScopedTemplate) {
         this.preProcessValue(val);
         this.postProcessValue(val);
       } else

src/utils/generator.js

@@ -1067,7 +1067,7 @@ export class Generator {
     let id = this.preludeGenerator.nameGenerator.generate("derived");
     let value = buildValue(id);
     value.intrinsicNameGenerated = true;
-    value._isScopedTemplate = true; // because this object doesn't exist ahead of time, and the visitor would otherwise declare it in the common scope
+    value.isScopedTemplate = true; // because this object doesn't exist ahead of time, and the visitor would otherwise declare it in the common scope
     invariant(value.intrinsicName === id);
     this._addDerivedEntry({
       isPure: optionalArgs ? optionalArgs.isPure : undefined,

src/values/ArrayValue.js

@@ -242,7 +242,8 @@ export default class ArrayValue extends ObjectValue {
   }
 
   static isIntrinsicAndHasWidenedNumericProperty(obj: Value): boolean {
-    if (obj instanceof ArrayValue && obj.intrinsicName !== undefined) {
+    if (obj instanceof ArrayValue && obj.intrinsicName !== undefined && obj.isScopedTemplate !== undefined) {
+      invariant(ObjectValue.isIntrinsicDerivedObject(obj));
       const prop = obj.unknownProperty;
       if (prop !== undefined && prop.descriptor !== undefined) {
         const desc = prop.descriptor.throwIfNotConcrete(obj.$Realm);

src/values/ObjectValue.js

@@ -279,7 +279,7 @@ export default class ObjectValue extends ConcreteValue {
 
   // Specifies whether the object is a template that needs to be created in a scope
   // If set, this happened during object initialization and the value is never changed again, so not tracked.
-  _isScopedTemplate: void | true;
+  isScopedTemplate: void | true;
 
   // If true, then unknown properties should return transitively simple abstract object values
   _simplicityIsTransitive: AbstractValue | BooleanValue;
@@ -718,4 +718,8 @@ export default class ObjectValue extends ConcreteValue {
     if (pb.internalSlot && typeof pb.key === "string" && pb.key[0] === "_") return true;
     return false;
   }
+
+  static isIntrinsicDerivedObject(obj: Value): boolean {
+    return obj instanceof ObjectValue && obj.intrinsicName !== undefined && obj.isScopedTemplate !== undefined;
+  }
 }