feat: improve get literal value for conditional expression (#6000)

* feat: improve get literal value for conditional expression * more tests * Remove unnecessary comparison --------- Co-authored-by: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com> Co-authored-by: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>

Author: ahabhgk

src/ast/nodes/ConditionalExpression.ts

@@ -16,7 +16,7 @@ import { tryCastLiteralValueToBoolean } from '../utils/tryCastLiteralValueToBool
 import type * as NodeType from './NodeType';
 import { Flag, isFlagSet, setFlag } from './shared/BitFlags';
 import type { ExpressionEntity, LiteralValueOrUnknown } from './shared/Expression';
-import { UnknownValue } from './shared/Expression';
+import { UnknownFalsyValue, UnknownTruthyValue, UnknownValue } from './shared/Expression';
 import { MultiExpression } from './shared/MultiExpression';
 import type { ExpressionNode, IncludeChildren } from './shared/Node';
 import { doNotDeoptimize, NodeBase, onlyIncludeSelfNoDeoptimize } from './shared/Node';
@@ -78,7 +78,18 @@ export default class ConditionalExpression extends NodeBase implements Deoptimiz
 origin: DeoptimizableEntity
 ): LiteralValueOrUnknown {
 const usedBranch = this.getUsedBranch();
-if (!usedBranch) return UnknownValue;
+if (!usedBranch) {
+const consequentValue = this.consequent.getLiteralValueAtPath(path, recursionTracker, origin);
+const castedConsequentValue = tryCastLiteralValueToBoolean(consequentValue);
+if (castedConsequentValue === UnknownValue) return UnknownValue;
+const alternateValue = this.alternate.getLiteralValueAtPath(path, recursionTracker, origin);
+const castedAlternateValue = tryCastLiteralValueToBoolean(alternateValue);
+if (castedConsequentValue !== castedAlternateValue) return UnknownValue;
+this.expressionsToBeDeoptimized.push(origin);
+if (consequentValue !== alternateValue)
+return castedConsequentValue ? UnknownTruthyValue : UnknownFalsyValue;
+return consequentValue;
+}
 this.expressionsToBeDeoptimized.push(origin);
 return usedBranch.getLiteralValueAtPath(path, recursionTracker, origin);
 }

test/form/samples/treeshake-if-statement/_expected.js

@@ -5,3 +5,9 @@
 if (typeof parseInt === 'function' ?? 'a' === 'a') {
 assert.ok(true);
 }
+
+if (!(unknownGlobal ? 'asdf' : true)) ;
+
+if (unknownGlobal ? 0 : false) ;
+
+if (!(unknownGlobal ? 'a' === 'a' : true)) ;

test/form/samples/treeshake-if-statement/main.js

@@ -9,3 +9,15 @@ if (typeof parseInt === 'function' || 'a' === 'a') {
 if (typeof parseInt === 'function' ?? 'a' === 'a') {
 assert.ok(true);
 }
+
+if (!(unknownGlobal ? 'asdf' : true)) {
+assert.ok(false);
+}
+
+if (unknownGlobal ? 0 : false) {
+assert.ok(false);
+}
+
+if (!(unknownGlobal ? 'a' === 'a' : true)) {
+assert.ok(false);
+}