From 951b2fa770633164dbeedceb9b3c4ec2a2a1ebe1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Steven=20Sch=C3=A4fer?= <stevenschaefer@google.com>
Date: Wed, 29 Jan 2020 15:43:14 +0100
Subject: [PATCH] JVM IR: Optimize type checks to null checks if possible

---
 .../kotlin/backend/jvm/lower/TypeOperatorLowering.kt       | 2 ++
 .../genericParameterBridge/notNullAnyMC.kt                 | 7 +++++--
 .../genericParameterBridge/notNullParamMC.kt               | 7 +++++--
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/TypeOperatorLowering.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/TypeOperatorLowering.kt
index 17d774daa6c..c68dec9dc7e 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/TypeOperatorLowering.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/TypeOperatorLowering.kt
@@ -69,6 +69,8 @@ private class TypeOperatorLowering(private val context: JvmBackendContext) : Fil
                     )
                 }
             }
+            argument.type.isNullable() && !type.isNullable() && argument.type.erasedUpperBound == type.erasedUpperBound ->
+                irNotEquals(argument, irNull())
             else -> irIs(argument, type.makeNotNull())
         }
     }
diff --git a/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullAnyMC.kt b/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullAnyMC.kt
index 0da6a697c53..4e73e898f7c 100644
--- a/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullAnyMC.kt
+++ b/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullAnyMC.kt
@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 abstract class A8 : MutableCollection<Any> {
     override fun contains(o: Any): Boolean {
         throw UnsupportedOperationException()
@@ -8,5 +7,9 @@ abstract class A8 : MutableCollection<Any> {
 // 1 bridge
 // 1 public final bridge size
 // 0 INSTANCEOF
-/* Only 1 IFNULL should be within contains method */
+
+/* Only 1 null check should be within the contains method */
+// JVM_TEMPLATES:
 // 1 IFNULL
+// JVM_IR_TEMPLATES:
+// 1 IFNONNULL
diff --git a/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullParamMC.kt b/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullParamMC.kt
index e3491e0b8df..2cde9869764 100644
--- a/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullParamMC.kt
+++ b/compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/notNullParamMC.kt
@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 abstract class A<T : Any> : MutableCollection<T> {
     override fun contains(o: T): Boolean {
         throw UnsupportedOperationException()
@@ -8,5 +7,9 @@ abstract class A<T : Any> : MutableCollection<T> {
 // 1 bridge
 // 1 public final bridge size
 // 0 INSTANCEOF
-/* Only 1 IFNULL should be within contains method (because T is not nullable) */
+
+/* Only 1 null check should be within the contains method (because T is not nullable) */
+// JVM_TEMPLATES:
 // 1 IFNULL
+// JVM_IR_TEMPLATES:
+// 1 IFNONNULL