From ec6108ee058ba18264dc834351258154ca629bcb Mon Sep 17 00:00:00 2001
From: Alexey Tsvetkov <alexey.tsvetkov@jetbrains.com>
Date: Fri, 8 Aug 2014 17:40:33 +0400
Subject: [PATCH] JS inline: remove unused local function instances

---
 .../org/jetbrains/k2js/inline/JsInliner.java  |  2 +
 .../inline/clean/LocalFunctionInstances.kt    | 76 +++++++++++++++++++
 2 files changed, 78 insertions(+)
 create mode 100644 js/js.inliner/src/org/jetbrains/k2js/inline/clean/LocalFunctionInstances.kt

diff --git a/js/js.inliner/src/org/jetbrains/k2js/inline/JsInliner.java b/js/js.inliner/src/org/jetbrains/k2js/inline/JsInliner.java
index fe2b9eb26cf..18336d71cfc 100644
--- a/js/js.inliner/src/org/jetbrains/k2js/inline/JsInliner.java
+++ b/js/js.inliner/src/org/jetbrains/k2js/inline/JsInliner.java
@@ -24,6 +24,7 @@ import java.util.IdentityHashMap;
 import java.util.Stack;
 import java.util.List;
 
+import static org.jetbrains.k2js.inline.clean.CleanPackage.removeUnusedLocalFunctionInstances;
 import static org.jetbrains.k2js.inline.FunctionInlineMutator.getInlineableCallReplacement;
 
 public class JsInliner extends JsVisitorWithContextImpl {
@@ -161,6 +162,7 @@ public class JsInliner extends JsVisitorWithContextImpl {
     @Override
     public void endVisit(JsFunction function, JsContext context) {
         super.endVisit(function, context);
+        removeUnusedLocalFunctionInstances(function);
         inliningContexts.pop();
     }
 
diff --git a/js/js.inliner/src/org/jetbrains/k2js/inline/clean/LocalFunctionInstances.kt b/js/js.inliner/src/org/jetbrains/k2js/inline/clean/LocalFunctionInstances.kt
new file mode 100644
index 00000000000..73c4d436022
--- /dev/null
+++ b/js/js.inliner/src/org/jetbrains/k2js/inline/clean/LocalFunctionInstances.kt
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2010-2014 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.k2js.inline.clean
+
+import com.google.dart.compiler.backend.js.ast.*
+
+import java.util.ArrayList
+import java.util.IdentityHashMap
+
+public fun removeUnusedLocalFunctionInstances(root: JsNode) {
+    val removable =
+            with(UnusedInstanceCollector()) {
+                accept(root)
+                removableInstances
+            }
+
+    GenericRemover(removable).accept(root)
+}
+
+private class UnusedInstanceCollector : JsVisitorWithContextImpl() {
+    private val tracker = ReferenceTracker<JsName, JsStatement>()
+
+    public val removableInstances: List<JsStatement>
+        get() = tracker.removable
+
+    override fun visit(x: JsVars.JsVar?, ctx: JsContext?): Boolean {
+        if (x == null) return false
+
+        if (!isLocalFunctionInstance(x)) return super.visit(x, ctx)
+
+        val name = x.getName()!!
+        val statementContext = getLastStatementLevelContext()
+        val currentNode = statementContext.getCurrentNode()
+        assert(currentNode is JsStatement) { "expected context containing statement" }
+        val currentStatement = currentNode as JsStatement
+        tracker.addCandidateForRemoval(name, currentStatement)
+
+        val references = collectReferencesInside(x)
+        references.filterNotNull()
+                  .forEach { tracker.addRemovableReference(name, it) }
+
+        return false
+    }
+
+    override fun visit(x: JsNameRef?, ctx: JsContext?): Boolean {
+        val name = x?.getName()
+
+        if (name != null) {
+            tracker.markReachable(name)
+        }
+
+        return false
+    }
+
+    private fun isLocalFunctionInstance(jsVar: JsVars.JsVar): Boolean {
+        val name = jsVar.getName()
+        val expr = jsVar.getInitExpression()
+        val staticRef = name?.getStaticRef()
+
+        return staticRef != null && staticRef == expr
+    }
+}
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