Fix incomplete computed property deoptimization

src/ast/nodes/MemberExpression.ts

@@ -11,6 +11,7 @@ import {
 	ObjectPath,
 	ObjectPathKey,
 	PathTracker,
+	UNKNOWN_PATH,
 	UnknownKey
 } from '../utils/PathTracker';
 import { LiteralValueOrUnknown, UnknownValue } from '../values';
@@ -77,6 +78,7 @@ export default class MemberExpression extends NodeBase implements DeoptimizableE
 
 	private bound = false;
 	private expressionsToBeDeoptimized: DeoptimizableEntity[] = [];
+	private hasDeoptimizedPath = false;
 	private replacement: string | null = null;
 
 	addExportedVariables(): void {}
@@ -112,6 +114,10 @@ export default class MemberExpression extends NodeBase implements DeoptimizableE
 	}
 
 	deoptimizeCache() {
+		this.propertyKey = UnknownKey;
+		if (this.hasDeoptimizedPath) {
+			this.object.deoptimizePath(UNKNOWN_PATH);
+		}
 		for (const expression of this.expressionsToBeDeoptimized) {
 			expression.deoptimizeCache();
 		}
@@ -124,7 +130,12 @@ export default class MemberExpression extends NodeBase implements DeoptimizableE
 			this.variable.deoptimizePath(path);
 		} else {
 			if (this.propertyKey === null) this.analysePropertyKey();
-			this.object.deoptimizePath([this.propertyKey as ObjectPathKey, ...path]);
+			if (this.propertyKey === UnknownKey) {
+				this.object.deoptimizePath(UNKNOWN_PATH);
+			} else {
+				this.hasDeoptimizedPath = true;
+				this.object.deoptimizePath([this.propertyKey as ObjectPathKey, ...path]);
+			}
 		}
 	}
 

src/ast/nodes/ObjectExpression.ts

@@ -36,11 +36,12 @@ interface PropertyMap {
 	};
 }
 
-export default class ObjectExpression extends NodeBase {
+export default class ObjectExpression extends NodeBase implements DeoptimizableEntity {
 	properties!: (Property | SpreadElement)[];
 	type!: NodeType.tObjectExpression;
 
 	private deoptimizedPaths = new Set<string>();
+
 	// We collect deoptimization information if we can resolve a computed property access
 	private expressionsToBeDeoptimized = new Map<string, DeoptimizableEntity[]>();
 	private hasUnknownDeoptimizedProperty = false;

test/function/samples/deoptimize-cached-prop/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'deoptimizes cached properties and return values if necessary (#3264)'
+};

test/function/samples/deoptimize-cached-prop/main.js

@@ -0,0 +1,24 @@
+const obj1 = {};
+let prop = 'x';
+
+updateProp();
+
+obj1[prop] = true;
+
+assert.strictEqual(obj1.y ? 'WORKING' : 'BUG', 'WORKING');
+
+function updateProp() {
+	prop = 'y';
+}
+
+const obj2 = {};
+obj2[getResult().prop] = 1;
+
+assert.equal(obj2.foo ? 'WORKING' : 'BUG', 'WORKING');
+
+function getResult() {
+	const result = {};
+	result.prop = 'foo';
+	return result;
+}
+