JS/Inlining: when generating expression for default property accessor, mark this expression as side effect free, so optimizer has opportunity to move it

js/js.translator/src/org/jetbrains/kotlin/js/translate/callTranslator/CallInfoExtensions.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.jetbrains.kotlin.js.translate.callTranslator
 import com.google.dart.compiler.backend.js.ast.JsEmptyExpression
 import com.google.dart.compiler.backend.js.ast.JsExpression
 import com.google.dart.compiler.backend.js.ast.JsName
+import com.google.dart.compiler.backend.js.ast.metadata.HasMetadata
+import com.google.dart.compiler.backend.js.ast.metadata.sideEffects
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.VariableDescriptor
@@ -73,7 +75,13 @@ fun VariableAccessInfo.constructAccessExpression(ref: JsExpression): JsExpressio
     if (isGetAccess()) {
         return ref
     } else {
-        return if (value !is JsEmptyExpression) JsAstUtils.assignment(ref, value!!) else context.emptyExpression
+        return if (value !is JsEmptyExpression) {
+            (ref as? HasMetadata)?.let { it.sideEffects = false }
+            JsAstUtils.assignment(ref, value!!)
+        }
+        else {
+            context.emptyExpression
+        }
     }
 }
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/callTranslator/VariableCallCases.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,10 +19,12 @@ package org.jetbrains.kotlin.js.translate.callTranslator
 import com.google.dart.compiler.backend.js.ast.JsExpression
 import com.google.dart.compiler.backend.js.ast.JsInvocation
 import com.google.dart.compiler.backend.js.ast.JsNameRef
+import com.google.dart.compiler.backend.js.ast.metadata.sideEffects
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.impl.LocalVariableDescriptor
 import org.jetbrains.kotlin.js.translate.context.Namer.getCapturedVarAccessor
+import org.jetbrains.kotlin.js.translate.utils.JsDescriptorUtils
 import org.jetbrains.kotlin.js.translate.utils.TranslationUtils
 import org.jetbrains.kotlin.resolve.BindingContextUtils.isVarCapturedInClosure
 import java.util.*
@@ -70,7 +72,12 @@ object DefaultVariableAccessCase : VariableAccessCase() {
     }
 
     override fun VariableAccessInfo.dispatchReceiver(): JsExpression {
-        return constructAccessExpression(JsNameRef(variableName, dispatchReceiver!!))
+        val accessor = JsNameRef(variableName, dispatchReceiver!!)
+        val descriptor = callableDescriptor
+        if (descriptor is PropertyDescriptor && JsDescriptorUtils.sideEffectsPossible(descriptor)) {
+            accessor.sideEffects = false
+        }
+        return constructAccessExpression(accessor)
     }
 
     override fun VariableAccessInfo.extensionReceiver(): JsExpression {

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/JsDescriptorUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -147,6 +147,10 @@ public final class JsDescriptorUtils {
         return accessorDescriptor == null || accessorDescriptor.isDefault();
     }
 
+    public static boolean sideEffectsPossible(@NotNull PropertyDescriptor property) {
+        return isDefaultAccessor(property.getGetter()) && !ModalityKt.isOverridableOrOverrides(property);
+    }
+
     public static boolean isSimpleFinalProperty(@NotNull PropertyDescriptor propertyDescriptor) {
         return !isExtension(propertyDescriptor) &&
                isDefaultAccessor(propertyDescriptor.getGetter()) &&