Always request a new tree-shaking pass when deoptimizations of a node…

… are first included (#4111)

src/Module.ts

@@ -109,6 +109,7 @@ export interface AstContext {
 	moduleContext: string;
 	nodeConstructors: { [name: string]: typeof NodeBase };
 	options: NormalizedInputOptions;
+	requestTreeshakingPass: () => void;
 	traceExport: (name: string) => Variable | null;
 	traceVariable: (name: string) => Variable | null;
 	usesTopLevelAwait: boolean;
@@ -726,6 +727,7 @@ export default class Module {
 			moduleContext: this.context,
 			nodeConstructors,
 			options: this.options,
+			requestTreeshakingPass: () => (this.graph.needsTreeshakingPass = true),
 			traceExport: this.getVariableForExportName.bind(this),
 			traceVariable: this.traceVariable.bind(this),
 			usesTopLevelAwait: false,

src/ast/nodes/AssignmentExpression.ts

@@ -126,5 +126,6 @@ export default class AssignmentExpression extends NodeBase {
 		this.deoptimized = true;
 		this.left.deoptimizePath(EMPTY_PATH);
 		this.right.deoptimizePath(UNKNOWN_PATH);
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/AssignmentPattern.ts

@@ -48,5 +48,6 @@ export default class AssignmentPattern extends NodeBase implements PatternNode {
 		this.deoptimized = true;
 		this.left.deoptimizePath(EMPTY_PATH);
 		this.right.deoptimizePath(UNKNOWN_PATH);
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/CallExpression.ts

@@ -298,6 +298,7 @@ export default class CallExpression extends NodeBase implements DeoptimizableEnt
 			// This will make sure all properties of parameters behave as "unknown"
 			argument.deoptimizePath(UNKNOWN_PATH);
 		}
+		this.context.requestTreeshakingPass();
 	}
 
 	private getReturnExpression(

src/ast/nodes/ForInStatement.ts

@@ -65,5 +65,6 @@ export default class ForInStatement extends StatementBase {
 	protected applyDeoptimizations(): void {
 		this.deoptimized = true;
 		this.left.deoptimizePath(EMPTY_PATH);
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/ForOfStatement.ts

@@ -50,5 +50,6 @@ export default class ForOfStatement extends StatementBase {
 	protected applyDeoptimizations(): void {
 		this.deoptimized = true;
 		this.left.deoptimizePath(EMPTY_PATH);
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/Identifier.ts

@@ -178,6 +178,7 @@ export default class Identifier extends NodeBase implements PatternNode {
 		this.deoptimized = true;
 		if (this.variable !== null && this.variable instanceof LocalVariable) {
 			this.variable.consolidateInitializers();
+			this.context.requestTreeshakingPass();
 		}
 	}
 

src/ast/nodes/MemberExpression.ts

@@ -329,6 +329,7 @@ export default class MemberExpression extends NodeBase implements DeoptimizableE
 					SHARED_RECURSION_TRACKER
 				);
 			}
+			this.context.requestTreeshakingPass();
 		}
 	}
 

src/ast/nodes/NewExpression.ts

@@ -46,5 +46,6 @@ export default class NewExpression extends NodeBase {
 			// This will make sure all properties of parameters behave as "unknown"
 			argument.deoptimizePath(UNKNOWN_PATH);
 		}
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/Property.ts

@@ -46,6 +46,7 @@ export default class Property extends MethodBase implements PatternNode {
 		this.deoptimized = true;
 		if (this.declarationInit !== null) {
 			this.declarationInit.deoptimizePath([UnknownKey, UnknownKey]);
+			this.context.requestTreeshakingPass();
 		}
 	}
 }

src/ast/nodes/RestElement.ts

@@ -37,6 +37,7 @@ export default class RestElement extends NodeBase implements PatternNode {
 		this.deoptimized = true;
 		if (this.declarationInit !== null) {
 			this.declarationInit.deoptimizePath([UnknownKey, UnknownKey]);
+			this.context.requestTreeshakingPass();
 		}
 	}
 }

src/ast/nodes/SpreadElement.ts

@@ -30,5 +30,6 @@ export default class SpreadElement extends NodeBase {
 		// Only properties of properties of the argument could become subject to reassignment
 		// This will also reassign the return values of iterators
 		this.argument.deoptimizePath([UnknownKey, UnknownKey]);
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/UnaryExpression.ts

@@ -59,6 +59,7 @@ export default class UnaryExpression extends NodeBase {
 		this.deoptimized = true;
 		if (this.operator === 'delete') {
 			this.argument.deoptimizePath(EMPTY_PATH);
+			this.context.requestTreeshakingPass();
 		}
 	}
 }

src/ast/nodes/UpdateExpression.ts

@@ -87,5 +87,6 @@ export default class UpdateExpression extends NodeBase {
 			const variable = this.scope.findVariable(this.argument.name);
 			variable.isReassigned = true;
 		}
+		this.context.requestTreeshakingPass();
 	}
 }

src/ast/nodes/YieldExpression.ts

@@ -30,6 +30,10 @@ export default class YieldExpression extends NodeBase {
 
 	protected applyDeoptimizations(): void {
 		this.deoptimized = true;
-		this.argument?.deoptimizePath(UNKNOWN_PATH);
+		const { argument } = this;
+		if (argument) {
+			argument.deoptimizePath(UNKNOWN_PATH);
+			this.context.requestTreeshakingPass();
+		}
 	}
 }

test/function/samples/deoptimize-request-treeshaking-pass/_config.js

@@ -0,0 +1,10 @@
+const assert = require('assert');
+const result = { value: 0 };
+
+module.exports = {
+	description: 'makes sure to request additional passes when a variable is deoptimized',
+	context: { result },
+	exports() {
+		assert.strictEqual(result.value, 2);
+	}
+};

test/function/samples/deoptimize-request-treeshaking-pass/main.js

@@ -0,0 +1,17 @@
+function heisenbug() {
+	var a = false;
+	function f(b) {
+		if (a) a === b.c ? result.value++ : result.value--;
+		a = b.c;
+	}
+	function g() {}
+	function h() {
+		f({
+			c: g
+		});
+	}
+	h();
+	h();
+}
+heisenbug();
+heisenbug();