From d1f884bad9c9e857a40326edcb54dfa5544d66bd Mon Sep 17 00:00:00 2001
From: Alexander Udalov <alexander.udalov@jetbrains.com>
Date: Thu, 24 Aug 2023 12:16:14 +0200
Subject: [PATCH] JVM IR: micro-optimization in IrType.erasedUpperBound

Avoid `is` on interfaces, use classes instead.
---
 .../kotlin/backend/jvm/ir/JvmIrTypeUtils.kt       | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrTypeUtils.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrTypeUtils.kt
index 17b75ea5c4c..eb86d3e8a22 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrTypeUtils.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrTypeUtils.kt
@@ -91,13 +91,16 @@ val IrTypeParameter.erasedUpperBound: IrClass
     }
 
 val IrType.erasedUpperBound: IrClass
-    get() =
-        when (val classifier = classifierOrNull) {
-            is IrClassSymbol -> classifier.owner
-            is IrTypeParameterSymbol -> classifier.owner.erasedUpperBound
-            is IrScriptSymbol -> classifier.owner.targetClass!!.owner
-            null -> if (this is IrErrorType) symbol.owner else error(render())
+    get() = when (this) {
+        is IrSimpleType -> when (val classifier = classifier.owner) {
+            is IrClass -> classifier
+            is IrTypeParameter -> classifier.erasedUpperBound
+            is IrScript -> classifier.targetClass!!.owner
+            else -> error(render())
         }
+        is IrErrorType -> symbol.owner
+        else -> error(render())
+    }
 
 /**
  * Get the default null/0 value for the type.