Avoid memory issues with hoisted variables

src/ast/nodes/Identifier.ts

@@ -60,7 +60,7 @@ export default class Identifier extends NodeBase implements PatternNode {
 				variable = this.scope.addDeclaration(this, this.context, init, true);
 				if (treeshake && treeshake.correctVarValueBeforeDeclaration) {
 					// Necessary to make sure the init is deoptimized. We cannot call deoptimizePath here.
-					this.scope.addDeclaration(this, this.context, UNDEFINED_EXPRESSION, true);
+					variable.markInitializersForDeoptimization();
 				}
 				break;
 			case 'function':

src/ast/scopes/BlockScope.ts

@@ -1,7 +1,6 @@
 import { AstContext } from '../../Module';
 import Identifier from '../nodes/Identifier';
 import { ExpressionEntity } from '../nodes/shared/Expression';
-import { UNDEFINED_EXPRESSION } from '../values';
 import LocalVariable from '../variables/LocalVariable';
 import ChildScope from './ChildScope';
 
@@ -13,10 +12,11 @@ export default class BlockScope extends ChildScope {
 		isHoisted: boolean
 	): LocalVariable {
 		if (isHoisted) {
-			this.parent.addDeclaration(identifier, context, init, isHoisted);
+			const variable = this.parent.addDeclaration(identifier, context, init, isHoisted);
 			// Necessary to make sure the init is deoptimized for conditional declarations.
 			// We cannot call deoptimizePath here.
-			return this.parent.addDeclaration(identifier, context, UNDEFINED_EXPRESSION, isHoisted);
+			variable.markInitializersForDeoptimization();
+			return variable;
 		} else {
 			return super.addDeclaration(identifier, context, init, false);
 		}

src/ast/variables/LocalVariable.ts

@@ -21,7 +21,6 @@ import Variable from './Variable';
 const MAX_PATH_DEPTH = 7;
 
 export default class LocalVariable extends Variable {
-	additionalInitializers: ExpressionEntity[] | null = null;
 	calledFromTryStatement = false;
 	declarations: (Identifier | ExportDefaultDeclaration)[];
 	init: ExpressionEntity | null;
@@ -30,6 +29,7 @@ export default class LocalVariable extends Variable {
 	// Caching and deoptimization:
 	// We track deoptimization when we do not return something unknown
 	protected deoptimizationTracker: PathTracker;
+	private additionalInitializers: ExpressionEntity[] | null = null;
 	private expressionsToBeDeoptimized: DeoptimizableEntity[] = [];
 
 	constructor(
@@ -47,13 +47,9 @@ export default class LocalVariable extends Variable {
 
 	addDeclaration(identifier: Identifier, init: ExpressionEntity | null): void {
 		this.declarations.push(identifier);
-		if (this.additionalInitializers === null) {
-			this.additionalInitializers = this.init === null ? [] : [this.init];
-			this.init = UNKNOWN_EXPRESSION;
-			this.isReassigned = true;
-		}
+		const additionalInitializers = this.markInitializersForDeoptimization();
 		if (init !== null) {
-			this.additionalInitializers.push(init);
+			additionalInitializers.push(init);
 		}
 	}
 
@@ -212,4 +208,13 @@ export default class LocalVariable extends Variable {
 	markCalledFromTryStatement(): void {
 		this.calledFromTryStatement = true;
 	}
+
+	markInitializersForDeoptimization(): ExpressionEntity[] {
+		if (this.additionalInitializers === null) {
+			this.additionalInitializers = this.init === null ? [] : [this.init];
+			this.init = UNKNOWN_EXPRESSION;
+			this.isReassigned = true;
+		}
+		return this.additionalInitializers;
+	}
 }