# HG changeset patch
# User attila
# Date 1413799596 -7200
# Node ID 03c06c337d9d296946bde9c71a3b9c4bc74c160b
# Parent  8c51767d534d8d5ec83506352a600733241b4ee0
8059844: Implement optimistic splitter
Reviewed-by: hannesw, lagergren

diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/ApplySpecialization.java
--- a/src/jdk/nashorn/internal/codegen/ApplySpecialization.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/ApplySpecialization.java	Mon Oct 20 12:06:36 2014 +0200
@@ -27,6 +27,7 @@
 
 import static jdk.nashorn.internal.codegen.CompilerConstants.ARGUMENTS_VAR;
 import static jdk.nashorn.internal.codegen.CompilerConstants.EXPLODED_ARGUMENT_PREFIX;
+
 import java.lang.invoke.MethodType;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
@@ -38,6 +39,7 @@
 import jdk.nashorn.internal.ir.CallNode;
 import jdk.nashorn.internal.ir.Expression;
 import jdk.nashorn.internal.ir.FunctionNode;
+import jdk.nashorn.internal.ir.FunctionNode.CompilationState;
 import jdk.nashorn.internal.ir.IdentNode;
 import jdk.nashorn.internal.ir.LexicalContext;
 import jdk.nashorn.internal.ir.Node;
@@ -321,7 +323,7 @@
 
         explodedArguments.pop();
 
-        return newFunctionNode;
+        return newFunctionNode.setState(lc, CompilationState.BUILTINS_TRANSFORMED);
     }
 
     private static boolean isApply(final CallNode callNode) {
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/AssignSymbols.java
--- a/src/jdk/nashorn/internal/codegen/AssignSymbols.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/AssignSymbols.java	Mon Oct 20 12:06:36 2014 +0200
@@ -76,7 +76,6 @@
 import jdk.nashorn.internal.ir.Node;
 import jdk.nashorn.internal.ir.RuntimeNode;
 import jdk.nashorn.internal.ir.RuntimeNode.Request;
-import jdk.nashorn.internal.ir.SplitNode;
 import jdk.nashorn.internal.ir.Statement;
 import jdk.nashorn.internal.ir.SwitchNode;
 import jdk.nashorn.internal.ir.Symbol;
@@ -135,9 +134,6 @@
         if (!(functionNode.hasScopeBlock() || functionNode.needsParentScope())) {
             functionNode.compilerConstant(SCOPE).setNeedsSlot(false);
         }
-        if (!functionNode.usesReturnSymbol()) {
-            functionNode.compilerConstant(RETURN).setNeedsSlot(false);
-        }
         // Named function expressions that end up not referencing themselves won't need a local slot for the self symbol.
         if(!functionNode.isDeclared() && !functionNode.usesSelfSymbol() && !functionNode.isAnonymous()) {
             final Symbol selfSymbol = functionNode.getBody().getExistingSymbol(functionNode.getIdent().getName());
@@ -1014,7 +1010,7 @@
         boolean previousWasBlock = false;
         for (final Iterator<LexicalContextNode> it = lc.getAllNodes(); it.hasNext();) {
             final LexicalContextNode node = it.next();
-            if (node instanceof FunctionNode || node instanceof SplitNode || isSplitArray(node)) {
+            if (node instanceof FunctionNode || isSplitArray(node)) {
                 // We reached the function boundary or a splitting boundary without seeing a definition for the symbol.
                 // It needs to be in scope.
                 return true;
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/AstSerializer.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/codegen/AstSerializer.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.nashorn.internal.codegen;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectOutputStream;
+import java.util.Collections;
+import java.util.zip.Deflater;
+import java.util.zip.DeflaterOutputStream;
+import jdk.nashorn.internal.ir.Block;
+import jdk.nashorn.internal.ir.FunctionNode;
+import jdk.nashorn.internal.ir.LexicalContext;
+import jdk.nashorn.internal.ir.Node;
+import jdk.nashorn.internal.ir.Statement;
+import jdk.nashorn.internal.ir.visitor.NodeVisitor;
+import jdk.nashorn.internal.runtime.options.Options;
+
+/**
+ * This static utility class performs serialization of FunctionNode ASTs to a byte array.
+ * The format is a standard Java serialization stream, deflated.
+ */
+final class AstSerializer {
+    // Experimentally, we concluded that compression level 4 gives a good tradeoff between serialization speed
+    // and size.
+    private static final int COMPRESSION_LEVEL = Options.getIntProperty("nashorn.serialize.compression", 4);
+    static byte[] serialize(final FunctionNode fn) {
+        final ByteArrayOutputStream out = new ByteArrayOutputStream();
+        try (final ObjectOutputStream oout = new ObjectOutputStream(new DeflaterOutputStream(out,
+                new Deflater(COMPRESSION_LEVEL)))) {
+            oout.writeObject(removeInnerFunctionBodies(fn));
+        } catch (final IOException e) {
+            throw new AssertionError("Unexpected exception serializing function", e);
+        }
+        return out.toByteArray();
+    }
+
+    private static FunctionNode removeInnerFunctionBodies(final FunctionNode fn) {
+        return (FunctionNode)fn.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
+            @Override
+            public Node leaveBlock(final Block block) {
+                if (lc.isFunctionBody() && lc.getFunction(block) != lc.getOutermostFunction()) {
+                    return block.setStatements(lc, Collections.<Statement>emptyList());
+                }
+                return super.leaveBlock(block);
+            }
+        });
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/ClassEmitter.java
--- a/src/jdk/nashorn/internal/codegen/ClassEmitter.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/ClassEmitter.java	Mon Oct 20 12:06:36 2014 +0200
@@ -51,6 +51,7 @@
 import static jdk.nashorn.internal.codegen.CompilerConstants.methodDescriptor;
 import static jdk.nashorn.internal.codegen.CompilerConstants.typeDescriptor;
 import static jdk.nashorn.internal.codegen.CompilerConstants.virtualCallNoLookup;
+
 import java.io.ByteArrayOutputStream;
 import java.io.PrintWriter;
 import java.security.AccessController;
@@ -64,7 +65,6 @@
 import jdk.internal.org.objectweb.asm.util.TraceClassVisitor;
 import jdk.nashorn.internal.codegen.types.Type;
 import jdk.nashorn.internal.ir.FunctionNode;
-import jdk.nashorn.internal.ir.SplitNode;
 import jdk.nashorn.internal.ir.debug.NashornClassReader;
 import jdk.nashorn.internal.ir.debug.NashornTextifier;
 import jdk.nashorn.internal.runtime.Context;
@@ -476,12 +476,6 @@
         methodsStarted.remove(method);
     }
 
-    SplitMethodEmitter method(final SplitNode splitNode, final String methodName, final Class<?> rtype, final Class<?>... ptypes) {
-        methodCount++;
-        methodNames.add(methodName);
-        return new SplitMethodEmitter(this, methodVisitor(EnumSet.of(Flag.PUBLIC, Flag.STATIC), methodName, rtype, ptypes), splitNode);
-    }
-
     /**
      * Add a new method to the class - defaults to public method
      *
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/CodeGenerator.java
--- a/src/jdk/nashorn/internal/codegen/CodeGenerator.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/CodeGenerator.java	Mon Oct 20 12:06:36 2014 +0200
@@ -34,9 +34,7 @@
 import static jdk.nashorn.internal.codegen.CompilerConstants.GET_STRING;
 import static jdk.nashorn.internal.codegen.CompilerConstants.QUICK_PREFIX;
 import static jdk.nashorn.internal.codegen.CompilerConstants.REGEX_PREFIX;
-import static jdk.nashorn.internal.codegen.CompilerConstants.RETURN;
 import static jdk.nashorn.internal.codegen.CompilerConstants.SCOPE;
-import static jdk.nashorn.internal.codegen.CompilerConstants.SPLIT_ARRAY_ARG;
 import static jdk.nashorn.internal.codegen.CompilerConstants.SPLIT_PREFIX;
 import static jdk.nashorn.internal.codegen.CompilerConstants.THIS;
 import static jdk.nashorn.internal.codegen.CompilerConstants.VARARGS;
@@ -99,10 +97,10 @@
 import jdk.nashorn.internal.ir.ForNode;
 import jdk.nashorn.internal.ir.FunctionNode;
 import jdk.nashorn.internal.ir.FunctionNode.CompilationState;
+import jdk.nashorn.internal.ir.GetSplitState;
 import jdk.nashorn.internal.ir.IdentNode;
 import jdk.nashorn.internal.ir.IfNode;
 import jdk.nashorn.internal.ir.IndexNode;
-import jdk.nashorn.internal.ir.JoinPredecessor;
 import jdk.nashorn.internal.ir.JoinPredecessorExpression;
 import jdk.nashorn.internal.ir.JumpStatement;
 import jdk.nashorn.internal.ir.LabelNode;
@@ -121,7 +119,8 @@
 import jdk.nashorn.internal.ir.ReturnNode;
 import jdk.nashorn.internal.ir.RuntimeNode;
 import jdk.nashorn.internal.ir.RuntimeNode.Request;
-import jdk.nashorn.internal.ir.SplitNode;
+import jdk.nashorn.internal.ir.SetSplitState;
+import jdk.nashorn.internal.ir.SplitReturn;
 import jdk.nashorn.internal.ir.Statement;
 import jdk.nashorn.internal.ir.SwitchNode;
 import jdk.nashorn.internal.ir.Symbol;
@@ -493,8 +492,7 @@
         //walk up the chain from starting block and when we bump into the current function boundary, add the external
         //information.
         final FunctionNode fn   = lc.getCurrentFunction();
-        final int          fnId = fn.getId();
-        final int externalDepth = compiler.getScriptFunctionData(fnId).getExternalSymbolDepth(symbol.getName());
+        final int externalDepth = compiler.getScriptFunctionData(fn.getId()).getExternalSymbolDepth(symbol.getName());
 
         //count the number of scopes from this place to the start of the function
 
@@ -1048,6 +1046,13 @@
             }
 
             @Override
+            public boolean enterGetSplitState(final GetSplitState getSplitState) {
+                method.loadScope();
+                method.invoke(Scope.GET_SPLIT_STATE);
+                return false;
+            }
+
+            @Override
             public boolean enterDefault(final Node otherNode) {
                 // Must have handled all expressions that can legally be encountered.
                 throw new AssertionError(otherNode.getClass().getName());
@@ -1219,7 +1224,7 @@
         popScopesUntil(target);
         final Label targetLabel = jump.getTargetLabel(target);
         targetLabel.markAsBreakTarget();
-        method.splitAwareGoto(lc, targetLabel, target);
+        method._goto(targetLabel);
 
         return false;
     }
@@ -2029,10 +2034,10 @@
     }
 
     private void lineNumber(final int lineNumber) {
-        if (lineNumber != lastLineNumber) {
+        if (lineNumber != lastLineNumber && lineNumber != Node.NO_LINE_NUMBER) {
             method.lineNumber(lineNumber);
-        }
-        lastLineNumber = lineNumber;
+            lastLineNumber = lineNumber;
+        }
     }
 
     int getLastLineNumber() {
@@ -2079,13 +2084,14 @@
                 method.begin();
 
                 defineCommonSplitMethodParameters();
-                defineSplitMethodParameter(3, arrayType);
-
-                fixScopeSlot(currentFunction);
+                defineSplitMethodParameter(CompilerConstants.SPLIT_ARRAY_ARG.slot(), arrayType);
+
+                // NOTE: when this is no longer needed, SplitIntoFunctions will no longer have to add IS_SPLIT
+                // to synthetic functions, and FunctionNode.needsCallee() will no longer need to test for isSplit().
+                final int arraySlot = fixScopeSlot(currentFunction, 3);
 
                 lc.enterSplitNode();
 
-                final int arraySlot = SPLIT_ARRAY_ARG.slot();
                 for (int i = arrayUnit.getLo(); i < arrayUnit.getHi(); i++) {
                     method.load(arrayType, arraySlot);
                     storeElement(nodes, elementType, postsets[i]);
@@ -2700,73 +2706,6 @@
         method.convert(newRuntimeNode.getType());
     }
 
-    @Override
-    public boolean enterSplitNode(final SplitNode splitNode) {
-        if(!method.isReachable()) {
-            return false;
-        }
-
-        final CompileUnit splitCompileUnit = splitNode.getCompileUnit();
-
-        final FunctionNode fn   = lc.getCurrentFunction();
-        final String className  = splitCompileUnit.getUnitClassName();
-        final String name       = splitNode.getName();
-
-        final Type returnType = fn.getReturnType();
-
-        final Class<?>   rtype          = fn.getReturnType().getTypeClass();
-        final boolean    needsArguments = fn.needsArguments();
-        final Class<?>[] ptypes         = needsArguments ?
-                new Class<?>[] {ScriptFunction.class, Object.class, ScriptObject.class, ScriptObject.class} :
-                new Class<?>[] {ScriptFunction.class, Object.class, ScriptObject.class};
-
-        final MethodEmitter caller = method;
-        unit = lc.pushCompileUnit(splitCompileUnit);
-
-        final Call splitCall = staticCallNoLookup(
-            className,
-            name,
-            methodDescriptor(rtype, ptypes));
-
-        final MethodEmitter splitEmitter =
-                splitCompileUnit.getClassEmitter().method(
-                        splitNode,
-                        name,
-                        rtype,
-                        ptypes);
-
-        pushMethodEmitter(splitEmitter);
-        method.setFunctionNode(fn);
-
-        assert fn.needsCallee() : "split function should require callee";
-        caller.loadCompilerConstant(CALLEE);
-        caller.loadCompilerConstant(THIS);
-        caller.loadCompilerConstant(SCOPE);
-        if (needsArguments) {
-            caller.loadCompilerConstant(ARGUMENTS);
-        }
-        caller.invoke(splitCall);
-        caller.storeCompilerConstant(RETURN, returnType);
-
-        method.begin();
-
-        defineCommonSplitMethodParameters();
-        if(needsArguments) {
-            defineSplitMethodParameter(3, ARGUMENTS);
-        }
-
-        // Copy scope to its target slot as first thing because the original slot could be used by return symbol.
-        fixScopeSlot(fn);
-
-        final int returnSlot = fn.compilerConstant(RETURN).getSlot(returnType);
-        method.defineBlockLocalVariable(returnSlot, returnSlot + returnType.getSlots());
-        method.loadUndefined(returnType);
-        method.storeCompilerConstant(RETURN, returnType);
-
-        lc.enterSplitNode();
-        return true;
-    }
-
     private void defineCommonSplitMethodParameters() {
         defineSplitMethodParameter(0, CALLEE);
         defineSplitMethodParameter(1, THIS);
@@ -2782,114 +2721,40 @@
         method.onLocalStore(type, slot);
     }
 
-    private void fixScopeSlot(final FunctionNode functionNode) {
+    private int fixScopeSlot(final FunctionNode functionNode, final int extraSlot) {
         // TODO hack to move the scope to the expected slot (needed because split methods reuse the same slots as the root method)
         final int actualScopeSlot = functionNode.compilerConstant(SCOPE).getSlot(SCOPE_TYPE);
         final int defaultScopeSlot = SCOPE.slot();
+        int newExtraSlot = extraSlot;
         if (actualScopeSlot != defaultScopeSlot) {
-            method.defineBlockLocalVariable(actualScopeSlot, actualScopeSlot + 1);
+            if (actualScopeSlot == extraSlot) {
+                newExtraSlot = extraSlot + 1;
+                method.defineBlockLocalVariable(newExtraSlot, newExtraSlot + 1);
+                method.load(Type.OBJECT, extraSlot);
+                method.storeHidden(Type.OBJECT, newExtraSlot);
+            } else {
+                method.defineBlockLocalVariable(actualScopeSlot, actualScopeSlot + 1);
+            }
             method.load(SCOPE_TYPE, defaultScopeSlot);
             method.storeCompilerConstant(SCOPE);
         }
+        return newExtraSlot;
     }
 
     @Override
-    public Node leaveSplitNode(final SplitNode splitNode) {
-        assert method instanceof SplitMethodEmitter;
-        lc.exitSplitNode();
-        final boolean hasReturn = method.hasReturn();
-        final SplitMethodEmitter splitMethod = ((SplitMethodEmitter)method);
-        final List<Label> targets = splitMethod.getExternalTargets();
-        final boolean hasControlFlow = hasReturn || !targets.isEmpty();
-        final List<BreakableNode> targetNodes  = splitMethod.getExternalTargetNodes();
-        final Type returnType = lc.getCurrentFunction().getReturnType();
-
-        try {
-            // Wrap up this method.
-
-            if(method.isReachable()) {
-                if (hasControlFlow) {
-                    method.setSplitState(-1);
-                }
-                method.loadCompilerConstant(RETURN, returnType);
-                method._return(returnType);
-            }
-            method.end();
-
-            lc.releaseSlots();
-
-            unit   = lc.popCompileUnit(splitNode.getCompileUnit());
-            popMethodEmitter();
-
-        } catch (final Throwable t) {
-            Context.printStackTrace(t);
-            final VerifyError e = new VerifyError("Code generation bug in \"" + splitNode.getName() + "\": likely stack misaligned: " + t + " " + getCurrentSource().getName());
-            e.initCause(t);
-            throw e;
-        }
-
-        //no external jump targets or return in switch node
-        if (!hasControlFlow) {
-            return splitNode;
-        }
-
-        // Handle return from split method if there was one.
-        final MethodEmitter caller = method;
-        final int     targetCount = targets.size();
-
-        caller.loadScope();
-        caller.invoke(Scope.GET_SPLIT_STATE);
-
-        final Label breakLabel = new Label("no_split_state");
-        // Split state is -1 for no split state, 0 for return, 1..n+1 for break/continue
-
-        //the common case is that we don't need a switch
-        if (targetCount == 0) {
-            assert hasReturn;
-            caller.ifne(breakLabel);
-            //has to be zero
-            caller.label(new Label("split_return"));
-            caller.loadCompilerConstant(RETURN, returnType);
-            caller._return(returnType);
-            caller.label(breakLabel);
-        } else {
-            assert !targets.isEmpty();
-
-            final int     low         = hasReturn ? 0 : 1;
-            final int     labelCount  = targetCount + 1 - low;
-            final Label[] labels      = new Label[labelCount];
-
-            for (int i = 0; i < labelCount; i++) {
-                labels[i] = new Label(i == 0 ? "split_return" : "split_" + targets.get(i - 1));
-            }
-            caller.tableswitch(low, targetCount, breakLabel, labels);
-            for (int i = low; i <= targetCount; i++) {
-                caller.label(labels[i - low]);
-                if (i == 0) {
-                    caller.loadCompilerConstant(RETURN, returnType);
-                    caller._return(returnType);
-                } else {
-                    final BreakableNode targetNode = targetNodes.get(i - 1);
-                    final Label label = targets.get(i - 1);
-                    if (!lc.isExternalTarget(splitNode, targetNode)) {
-                        final JoinPredecessor jumpOrigin = splitNode.getJumpOrigin(label);
-                        if(jumpOrigin != null) {
-                            method.beforeJoinPoint(jumpOrigin);
-                        }
-                        popScopesUntil(targetNode);
-                    }
-                    caller.splitAwareGoto(lc, label, targetNode);
-                }
-            }
-            caller.label(breakLabel);
-        }
-
-        // If split has a return and caller is itself a split method it needs to propagate the return.
-        if (hasReturn) {
-            caller.setHasReturn();
-        }
-
-        return splitNode;
+    public boolean enterSplitReturn(final SplitReturn splitReturn) {
+        if (method.isReachable()) {
+            method.loadUndefined(lc.getCurrentFunction().getReturnType())._return();
+        }
+        return false;
+    }
+
+    @Override
+    public boolean enterSetSplitState(final SetSplitState setSplitState) {
+        if (method.isReachable()) {
+            method.setSplitState(setSplitState.getState());
+        }
+        return false;
     }
 
     @Override
@@ -4379,11 +4244,7 @@
     private void newFunctionObject(final FunctionNode functionNode, final boolean addInitializer) {
         assert lc.peek() == functionNode;
 
-        final int fnId = functionNode.getId();
-
-        final RecompilableScriptFunctionData data = compiler.getScriptFunctionData(fnId);
-
-        assert data != null : functionNode.getName() + " has no data";
+        final RecompilableScriptFunctionData data = compiler.getScriptFunctionData(functionNode.getId());
 
         if (functionNode.isProgram() && !compiler.isOnDemandCompilation()) {
             final CompileUnit fnUnit = functionNode.getCompileUnit();
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/CompilationPhase.java
--- a/src/jdk/nashorn/internal/codegen/CompilationPhase.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/CompilationPhase.java	Mon Oct 20 12:06:36 2014 +0200
@@ -38,12 +38,11 @@
 import static jdk.nashorn.internal.ir.FunctionNode.CompilationState.SPLIT;
 import static jdk.nashorn.internal.ir.FunctionNode.CompilationState.SYMBOLS_ASSIGNED;
 import static jdk.nashorn.internal.runtime.logging.DebugLogger.quote;
+
 import java.io.PrintWriter;
-import java.util.ArrayList;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
@@ -53,10 +52,7 @@
 import jdk.nashorn.internal.ir.FunctionNode.CompilationState;
 import jdk.nashorn.internal.ir.LexicalContext;
 import jdk.nashorn.internal.ir.LiteralNode;
-import jdk.nashorn.internal.ir.LiteralNode.ArrayLiteralNode;
-import jdk.nashorn.internal.ir.LiteralNode.ArrayLiteralNode.ArrayUnit;
 import jdk.nashorn.internal.ir.Node;
-import jdk.nashorn.internal.ir.SplitNode;
 import jdk.nashorn.internal.ir.debug.ASTWriter;
 import jdk.nashorn.internal.ir.debug.PrintVisitor;
 import jdk.nashorn.internal.ir.visitor.NodeVisitor;
@@ -81,7 +77,7 @@
                 PARSED)) {
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            return (FunctionNode)fn.accept(new FoldConstants(compiler));
+            return transformFunction(fn, new FoldConstants(compiler));
         }
 
         @Override
@@ -104,7 +100,7 @@
                 CONSTANT_FOLDED)) {
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            return (FunctionNode)fn.accept(new Lower(compiler));
+            return transformFunction(fn, new Lower(compiler));
         }
 
         @Override
@@ -118,23 +114,6 @@
      * optimistic ops a program point so that an UnwarrantedException knows from where
      * a guess went wrong when creating the continuation to roll back this execution
      */
-    PROGRAM_POINT_PHASE(
-            EnumSet.of(
-                INITIALIZED,
-                PARSED,
-                CONSTANT_FOLDED,
-                LOWERED)) {
-        @Override
-        FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            return (FunctionNode)fn.accept(new ProgramPoints());
-        }
-
-        @Override
-        public String toString() {
-            return "'Program Point Calculation'";
-        }
-    },
-
     TRANSFORM_BUILTINS_PHASE(
             EnumSet.of(
                     INITIALIZED,
@@ -144,13 +123,7 @@
         //we only do this if we have a param type map, otherwise this is not a specialized recompile
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            final FunctionNode newFunctionNode = (FunctionNode)fn.accept(new ApplySpecialization(compiler));
-            return (FunctionNode)newFunctionNode.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
-                @Override
-                public Node leaveFunctionNode(final FunctionNode node) {
-                    return node.setState(lc, BUILTINS_TRANSFORMED);
-                }
-            });
+            return setStates(transformFunction(fn, new ApplySpecialization(compiler)), BUILTINS_TRANSFORMED);
         }
 
         @Override
@@ -177,7 +150,7 @@
             FunctionNode newFunctionNode;
 
             //ensure elementTypes, postsets and presets exist for splitter and arraynodes
-            newFunctionNode = (FunctionNode)fn.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
+            newFunctionNode = transformFunction(fn, new NodeVisitor<LexicalContext>(new LexicalContext()) {
                 @Override
                 public LiteralNode<?> leaveLiteralNode(final LiteralNode<?> literalNode) {
                     return literalNode.initialize(lc);
@@ -185,7 +158,7 @@
             });
 
             newFunctionNode = new Splitter(compiler, newFunctionNode, outermostCompileUnit).split(newFunctionNode, true);
-
+            newFunctionNode = transformFunction(newFunctionNode, new SplitIntoFunctions(compiler));
             assert newFunctionNode.getCompileUnit() == outermostCompileUnit : "fn=" + fn.getName() + ", fn.compileUnit (" + newFunctionNode.getCompileUnit() + ") != " + outermostCompileUnit;
             assert newFunctionNode.isStrict() == compiler.isStrict() : "functionNode.isStrict() != compiler.isStrict() for " + quote(newFunctionNode.getName());
 
@@ -198,6 +171,52 @@
         }
     },
 
+    PROGRAM_POINT_PHASE(
+            EnumSet.of(
+                    INITIALIZED,
+                    PARSED,
+                    CONSTANT_FOLDED,
+                    LOWERED,
+                    BUILTINS_TRANSFORMED,
+                    SPLIT)) {
+        @Override
+        FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
+            return transformFunction(fn, new ProgramPoints());
+        }
+
+        @Override
+        public String toString() {
+            return "'Program Point Calculation'";
+        }
+    },
+
+    SERIALIZE_SPLIT_PHASE(
+            EnumSet.of(
+                    INITIALIZED,
+                    PARSED,
+                    CONSTANT_FOLDED,
+                    LOWERED,
+                    BUILTINS_TRANSFORMED,
+                    SPLIT)) {
+        @Override
+        FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
+            return transformFunction(fn, new NodeVisitor<LexicalContext>(new LexicalContext()) {
+                @Override
+                public boolean enterFunctionNode(final FunctionNode functionNode) {
+                    if (functionNode.isSplit()) {
+                        compiler.serializeAst(functionNode);
+                    }
+                    return true;
+                }
+            });
+        }
+
+        @Override
+        public String toString() {
+            return "'Serialize Split Functions'";
+        }
+    },
+
     SYMBOL_ASSIGNMENT_PHASE(
             EnumSet.of(
                     INITIALIZED,
@@ -208,7 +227,7 @@
                     SPLIT)) {
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            return (FunctionNode)fn.accept(new AssignSymbols(compiler));
+            return transformFunction(fn, new AssignSymbols(compiler));
         }
 
         @Override
@@ -228,7 +247,7 @@
                     SYMBOLS_ASSIGNED)) {
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            return (FunctionNode)fn.accept(new FindScopeDepths(compiler));
+            return transformFunction(fn, new FindScopeDepths(compiler));
         }
 
         @Override
@@ -250,7 +269,7 @@
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
             if (compiler.useOptimisticTypes()) {
-                return (FunctionNode)fn.accept(new OptimisticTypesCalculator(compiler));
+                return transformFunction(fn, new OptimisticTypesCalculator(compiler));
             }
             return setStates(fn, OPTIMISTIC_TYPES_ASSIGNED);
         }
@@ -274,8 +293,7 @@
                     OPTIMISTIC_TYPES_ASSIGNED)) {
         @Override
         FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
-            final FunctionNode newFunctionNode = (FunctionNode)fn.accept(new LocalVariableTypesCalculator(compiler));
-
+            final FunctionNode newFunctionNode = transformFunction(fn, new LocalVariableTypesCalculator(compiler));
             final ScriptEnvironment senv = compiler.getScriptEnvironment();
             final PrintWriter       err  = senv.getErr();
 
@@ -330,13 +348,7 @@
 
             for (final CompileUnit oldUnit : compiler.getCompileUnits()) {
                 assert map.get(oldUnit) == null;
-                final StringBuilder sb = new StringBuilder(compiler.nextCompileUnitName());
-                if (phases.isRestOfCompilation()) {
-                    sb.append("$restOf");
-                }
-                //it's ok to not copy the initCount, methodCount and clinitCount here, as codegen is what
-                //fills those out anyway. Thus no need for a copy constructor
-                final CompileUnit newUnit = compiler.createCompileUnit(sb.toString(), oldUnit.getWeight());
+                final CompileUnit newUnit = createNewCompileUnit(compiler, phases);
                 log.fine("Creating new compile unit ", oldUnit, " => ", newUnit);
                 map.put(oldUnit, newUnit);
                 assert newUnit != null;
@@ -350,47 +362,10 @@
             //replace old compile units in function nodes, if any are assigned,
             //for example by running the splitter on this function node in a previous
             //partial code generation
-            final FunctionNode newFunctionNode = (FunctionNode)fn.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
-                @Override
-                public Node leaveFunctionNode(final FunctionNode node) {
-                    final CompileUnit oldUnit = node.getCompileUnit();
-                    assert oldUnit != null : "no compile unit in function node";
-
-                    final CompileUnit newUnit = map.get(oldUnit);
-                    assert newUnit != null : "old unit has no mapping to new unit " + oldUnit;
-
-                    log.fine("Replacing compile unit: ", oldUnit, " => ", newUnit, " in ", quote(node.getName()));
-                    return node.setCompileUnit(lc, newUnit).setState(lc, CompilationState.COMPILE_UNITS_REUSED);
-                }
-
+            final FunctionNode newFunctionNode = transformFunction(fn, new ReplaceCompileUnits() {
                 @Override
-                public Node leaveSplitNode(final SplitNode node) {
-                    final CompileUnit oldUnit = node.getCompileUnit();
-                    assert oldUnit != null : "no compile unit in function node";
-
-                    final CompileUnit newUnit = map.get(oldUnit);
-                    assert newUnit != null : "old unit has no mapping to new unit " + oldUnit;
-
-                    log.fine("Replacing compile unit: ", oldUnit, " => ", newUnit, " in ", quote(node.getName()));
-                    return node.setCompileUnit(lc, newUnit);
-                }
-
-                @Override
-                public Node leaveLiteralNode(final LiteralNode<?> node) {
-                    if (node instanceof ArrayLiteralNode) {
-                        final ArrayLiteralNode aln = (ArrayLiteralNode)node;
-                        if (aln.getUnits() == null) {
-                            return node;
-                        }
-                        final List<ArrayUnit> newArrayUnits = new ArrayList<>();
-                        for (final ArrayUnit au : aln.getUnits()) {
-                            final CompileUnit newUnit = map.get(au.getCompileUnit());
-                            assert newUnit != null;
-                            newArrayUnits.add(new ArrayUnit(newUnit, au.getLo(), au.getHi()));
-                        }
-                        return aln.setUnits(lc, newArrayUnits);
-                    }
-                    return node;
+                CompileUnit getReplacement(CompileUnit original) {
+                    return map.get(original);
                 }
 
                 @Override
@@ -408,7 +383,59 @@
         }
     },
 
-     /**
+    REINITIALIZE_SERIALIZED(
+            EnumSet.of(
+                    INITIALIZED,
+                    PARSED,
+                    CONSTANT_FOLDED,
+                    LOWERED,
+                    BUILTINS_TRANSFORMED,
+                    SPLIT)) {
+        @Override
+        FunctionNode transform(final Compiler compiler, final CompilationPhases phases, final FunctionNode fn) {
+            final Set<CompileUnit> unitSet = CompileUnit.createCompileUnitSet();
+            final Map<CompileUnit, CompileUnit> unitMap = new HashMap<>();
+
+            // Ensure that the FunctionNode's compile unit is the first in the list of new units. Install phase
+            // will use that as the root class.
+            createCompileUnit(fn.getCompileUnit(), unitSet, unitMap, compiler, phases);
+
+            final FunctionNode newFn = transformFunction(fn, new ReplaceCompileUnits() {
+                @Override
+                CompileUnit getReplacement(final CompileUnit oldUnit) {
+                    final CompileUnit existing = unitMap.get(oldUnit);
+                    if (existing != null) {
+                        return existing;
+                    }
+                    return createCompileUnit(oldUnit, unitSet, unitMap, compiler, phases);
+                }
+
+                @Override
+                public Node leaveFunctionNode(final FunctionNode fn2) {
+                    return super.leaveFunctionNode(
+                            // restore flags for deserialized nested function nodes
+                            compiler.getScriptFunctionData(fn2.getId()).restoreFlags(lc, fn2));
+                };
+            });
+            compiler.replaceCompileUnits(unitSet);
+            return newFn;
+        }
+
+        private CompileUnit createCompileUnit(final CompileUnit oldUnit, final Set<CompileUnit> unitSet,
+                final Map<CompileUnit, CompileUnit> unitMap, final Compiler compiler, final CompilationPhases phases) {
+            final CompileUnit newUnit = createNewCompileUnit(compiler, phases);
+            unitMap.put(oldUnit, newUnit);
+            unitSet.add(newUnit);
+            return newUnit;
+        }
+
+        @Override
+        public String toString() {
+            return "'Deserialize'";
+        }
+    },
+
+    /**
      * Bytecode generation:
      *
      * Generate the byte code class(es) resulting from the compiled FunctionNode
@@ -443,7 +470,7 @@
             try {
                 // Explicitly set BYTECODE_GENERATED here; it can not be set in case of skipping codegen for :program
                 // in the lazy + optimistic world. See CodeGenerator.skipFunction().
-                newFunctionNode = ((FunctionNode)newFunctionNode.accept(codegen)).setState(null, BYTECODE_GENERATED);
+                newFunctionNode = transformFunction(newFunctionNode, codegen).setState(null, BYTECODE_GENERATED);
                 codegen.generateScopeCalls();
             } catch (final VerifyError e) {
                 if (senv._verify_code || senv._print_code) {
@@ -615,7 +642,7 @@
         if (!AssertsEnabled.assertsEnabled()) {
             return functionNode;
         }
-        return (FunctionNode)functionNode.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
+        return transformFunction(functionNode, new NodeVisitor<LexicalContext>(new LexicalContext()) {
             @Override
             public Node leaveFunctionNode(final FunctionNode fn) {
                 return fn.setState(lc, state);
@@ -701,4 +728,17 @@
         return end(compiler, transform(compiler, phases, begin(compiler, functionNode)));
     }
 
+    private static FunctionNode transformFunction(final FunctionNode fn, final NodeVisitor<?> visitor) {
+        return (FunctionNode) fn.accept(visitor);
+    }
+
+    private static CompileUnit createNewCompileUnit(final Compiler compiler, final CompilationPhases phases) {
+        final StringBuilder sb = new StringBuilder(compiler.nextCompileUnitName());
+        if (phases.isRestOfCompilation()) {
+            sb.append("$restOf");
+        }
+        //it's ok to not copy the initCount, methodCount and clinitCount here, as codegen is what
+        //fills those out anyway. Thus no need for a copy constructor
+        return compiler.createCompileUnit(sb.toString(), 0);
+    }
 }
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/CompileUnit.java
--- a/src/jdk/nashorn/internal/codegen/CompileUnit.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/CompileUnit.java	Mon Oct 20 12:06:36 2014 +0200
@@ -28,11 +28,13 @@
 import java.io.Serializable;
 import java.util.Set;
 import java.util.TreeSet;
+import jdk.nashorn.internal.ir.CompileUnitHolder;
 
 /**
   * Used to track split class compilation. Note that instances of the class are serializable, but all fields are
   * transient, making the serialized version of the class only useful for tracking the referential topology of other
-  * AST nodes referencing the same or different compile units.
+  * AST nodes referencing the same or different compile units. We do want to preserve this topology though as
+  * {@link CompileUnitHolder}s in a deserialized AST will undergo reinitialization.
   */
 public final class CompileUnit implements Comparable<CompileUnit>, Serializable {
     private static final long serialVersionUID = 1L;
@@ -127,14 +129,6 @@
     }
 
     /**
-     * Get the current weight of the compile unit.
-     * @return the unit's weight
-     */
-    long getWeight() {
-        return weight;
-    }
-
-    /**
      * Check if this compile unit can hold {@code weight} more units of weight
      * @param w weight to check if can be added
      * @return true if weight fits in this compile unit
@@ -160,7 +154,7 @@
     }
 
     private static String shortName(final String name) {
-        return name.lastIndexOf('/') == -1 ? name : name.substring(name.lastIndexOf('/') + 1);
+        return name == null ? null : name.lastIndexOf('/') == -1 ? name : name.substring(name.lastIndexOf('/') + 1);
     }
 
     @Override
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/Compiler.java
--- a/src/jdk/nashorn/internal/codegen/Compiler.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/Compiler.java	Mon Oct 20 12:06:36 2014 +0200
@@ -32,15 +32,16 @@
 import static jdk.nashorn.internal.codegen.CompilerConstants.THIS;
 import static jdk.nashorn.internal.codegen.CompilerConstants.VARARGS;
 import static jdk.nashorn.internal.runtime.logging.DebugLogger.quote;
+
 import java.io.File;
 import java.lang.invoke.MethodType;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -159,75 +160,142 @@
      */
     private static final int COMPILE_UNIT_NAME_BUFFER_SIZE = 32;
 
+    private final Map<Integer, byte[]> serializedAsts = new HashMap<>();
+
     /**
      * Compilation phases that a compilation goes through
      */
     public static class CompilationPhases implements Iterable<CompilationPhase> {
 
-        /** Singleton that describes a standard eager compilation - this includes code installation */
-        public final static CompilationPhases COMPILE_ALL = new CompilationPhases(
-                "Compile all",
-                new CompilationPhase[] {
-                        CompilationPhase.CONSTANT_FOLDING_PHASE,
-                        CompilationPhase.LOWERING_PHASE,
-                        CompilationPhase.PROGRAM_POINT_PHASE,
-                        CompilationPhase.TRANSFORM_BUILTINS_PHASE,
-                        CompilationPhase.SPLITTING_PHASE,
-                        CompilationPhase.SYMBOL_ASSIGNMENT_PHASE,
-                        CompilationPhase.SCOPE_DEPTH_COMPUTATION_PHASE,
-                        CompilationPhase.OPTIMISTIC_TYPE_ASSIGNMENT_PHASE,
-                        CompilationPhase.LOCAL_VARIABLE_TYPE_CALCULATION_PHASE,
-                        CompilationPhase.BYTECODE_GENERATION_PHASE,
-                        CompilationPhase.INSTALL_PHASE
-                });
+        /**
+         * Singleton that describes compilation up to the phase where a function can be serialized.
+         */
+        private final static CompilationPhases COMPILE_UPTO_SERIALIZABLE = new CompilationPhases(
+                "Common initial phases",
+                CompilationPhase.CONSTANT_FOLDING_PHASE,
+                CompilationPhase.LOWERING_PHASE,
+                CompilationPhase.TRANSFORM_BUILTINS_PHASE,
+                CompilationPhase.SPLITTING_PHASE,
+                CompilationPhase.PROGRAM_POINT_PHASE,
+                CompilationPhase.SERIALIZE_SPLIT_PHASE
+                );
 
-        /** Compile all for a rest of method */
-        public final static CompilationPhases COMPILE_ALL_RESTOF =
-                COMPILE_ALL.setDescription("Compile all, rest of").addAfter(CompilationPhase.LOCAL_VARIABLE_TYPE_CALCULATION_PHASE, CompilationPhase.REUSE_COMPILE_UNITS_PHASE);
+        private final static CompilationPhases COMPILE_SERIALIZABLE_UPTO_BYTECODE = new CompilationPhases(
+                "After common phases, before bytecode generator",
+                CompilationPhase.SYMBOL_ASSIGNMENT_PHASE,
+                CompilationPhase.SCOPE_DEPTH_COMPUTATION_PHASE,
+                CompilationPhase.OPTIMISTIC_TYPE_ASSIGNMENT_PHASE,
+                CompilationPhase.LOCAL_VARIABLE_TYPE_CALCULATION_PHASE
+                );
 
-        /** Singleton that describes a standard eager compilation, but no installation, for example used by --compile-only */
-        public final static CompilationPhases COMPILE_ALL_NO_INSTALL =
-                COMPILE_ALL.
-                removeLast().
-                setDescription("Compile without install");
-
-        /** Singleton that describes compilation up to the CodeGenerator, but not actually generating code */
-        public final static CompilationPhases COMPILE_UPTO_BYTECODE =
-                COMPILE_ALL.
-                removeLast().
-                removeLast().
-                setDescription("Compile upto bytecode");
+        /**
+         * Singleton that describes additional steps to be taken after deserializing, all the way up to (but not
+         * including) generating and installing code.
+         */
+        public final static CompilationPhases RECOMPILE_SERIALIZED_UPTO_BYTECODE = new CompilationPhases(
+                "Recompile serialized function up to bytecode",
+                CompilationPhase.REINITIALIZE_SERIALIZED,
+                COMPILE_SERIALIZABLE_UPTO_BYTECODE
+                );
 
         /**
          * Singleton that describes back end of method generation, given that we have generated the normal
          * method up to CodeGenerator as in {@link CompilationPhases#COMPILE_UPTO_BYTECODE}
          */
-        public final static CompilationPhases COMPILE_FROM_BYTECODE = new CompilationPhases(
+        public final static CompilationPhases GENERATE_BYTECODE_AND_INSTALL = new CompilationPhases(
                 "Generate bytecode and install",
-                new CompilationPhase[] {
-                        CompilationPhase.BYTECODE_GENERATION_PHASE,
-                        CompilationPhase.INSTALL_PHASE
-                });
+                CompilationPhase.BYTECODE_GENERATION_PHASE,
+                CompilationPhase.INSTALL_PHASE
+                );
+
+        /** Singleton that describes compilation up to the CodeGenerator, but not actually generating code */
+        public final static CompilationPhases COMPILE_UPTO_BYTECODE = new CompilationPhases(
+                "Compile upto bytecode",
+                COMPILE_UPTO_SERIALIZABLE,
+                COMPILE_SERIALIZABLE_UPTO_BYTECODE);
+
+        /** Singleton that describes a standard eager compilation, but no installation, for example used by --compile-only */
+        public final static CompilationPhases COMPILE_ALL_NO_INSTALL = new CompilationPhases(
+                "Compile without install",
+                COMPILE_UPTO_BYTECODE,
+                CompilationPhase.BYTECODE_GENERATION_PHASE);
+
+        /** Singleton that describes a standard eager compilation - this includes code installation */
+        public final static CompilationPhases COMPILE_ALL = new CompilationPhases(
+                "Full eager compilation",
+                COMPILE_UPTO_BYTECODE,
+                GENERATE_BYTECODE_AND_INSTALL);
+
+        /** Singleton that describes a full compilation - this includes code installation - from serialized state*/
+        public final static CompilationPhases COMPILE_ALL_SERIALIZED = new CompilationPhases(
+                "Eager compilation from serializaed state",
+                RECOMPILE_SERIALIZED_UPTO_BYTECODE,
+                GENERATE_BYTECODE_AND_INSTALL);
 
         /**
          * Singleton that describes restOf method generation, given that we have generated the normal
          * method up to CodeGenerator as in {@link CompilationPhases#COMPILE_UPTO_BYTECODE}
          */
-        public final static CompilationPhases COMPILE_FROM_BYTECODE_RESTOF =
-                COMPILE_FROM_BYTECODE.
-                addFirst(CompilationPhase.REUSE_COMPILE_UNITS_PHASE).
-                setDescription("Generate bytecode and install - RestOf method");
+        public final static CompilationPhases GENERATE_BYTECODE_AND_INSTALL_RESTOF = new CompilationPhases(
+                "Generate bytecode and install - RestOf method",
+                CompilationPhase.REUSE_COMPILE_UNITS_PHASE,
+                GENERATE_BYTECODE_AND_INSTALL);
+
+        /** Compile all for a rest of method */
+        public final static CompilationPhases COMPILE_ALL_RESTOF = new CompilationPhases(
+                "Compile all, rest of",
+                COMPILE_UPTO_BYTECODE,
+                GENERATE_BYTECODE_AND_INSTALL_RESTOF);
+
+        /** Compile from serialized for a rest of method */
+        public final static CompilationPhases COMPILE_SERIALIZED_RESTOF = new CompilationPhases(
+                "Compile serialized, rest of",
+                RECOMPILE_SERIALIZED_UPTO_BYTECODE,
+                GENERATE_BYTECODE_AND_INSTALL_RESTOF);
 
         private final List<CompilationPhase> phases;
 
         private final String desc;
 
         private CompilationPhases(final String desc, final CompilationPhase... phases) {
-            this.desc = desc;
+            this(desc, Arrays.asList(phases));
+        }
+
+        private CompilationPhases(final String desc, final CompilationPhases base, final CompilationPhase... phases) {
+            this(desc, concat(base.phases, Arrays.asList(phases)));
+        }
+
+        private CompilationPhases(final String desc, final CompilationPhase first, final CompilationPhases rest) {
+            this(desc, concat(Collections.singletonList(first), rest.phases));
+        }
+
+        private CompilationPhases(final String desc, final CompilationPhases base) {
+            this(desc, base.phases);
+        }
+
+        private CompilationPhases(final String desc, final CompilationPhases... bases) {
+            this(desc, concatPhases(bases));
+        }
 
-            final List<CompilationPhase> newPhases = new LinkedList<>();
-            newPhases.addAll(Arrays.asList(phases));
-            this.phases = Collections.unmodifiableList(newPhases);
+        private CompilationPhases(final String desc, final List<CompilationPhase> phases) {
+            this.desc = desc;
+            this.phases = phases;
+        }
+
+        private static List<CompilationPhase> concatPhases(final CompilationPhases[] bases) {
+            final ArrayList<CompilationPhase> l = new ArrayList<>();
+            for(final CompilationPhases base: bases) {
+                l.addAll(base.phases);
+            }
+            l.trimToSize();
+            return l;
+        }
+
+        private static <T> List<T> concat(final List<T> l1, final List<T> l2) {
+            final ArrayList<T> l = new ArrayList<>(l1);
+            l.addAll(l2);
+            l.trimToSize();
+            return l;
         }
 
         @Override
@@ -235,45 +303,6 @@
             return "'" + desc + "' " + phases.toString();
         }
 
-        private CompilationPhases setDescription(final String desc) {
-            return new CompilationPhases(desc, phases.toArray(new CompilationPhase[phases.size()]));
-        }
-
-        private CompilationPhases removeLast() {
-            final LinkedList<CompilationPhase> list = new LinkedList<>(phases);
-            list.removeLast();
-            return new CompilationPhases(desc, list.toArray(new CompilationPhase[list.size()]));
-        }
-
-        private CompilationPhases addFirst(final CompilationPhase phase) {
-            if (phases.contains(phase)) {
-                return this;
-            }
-            final LinkedList<CompilationPhase> list = new LinkedList<>(phases);
-            list.addFirst(phase);
-            return new CompilationPhases(desc, list.toArray(new CompilationPhase[list.size()]));
-        }
-
-        @SuppressWarnings("unused") //TODO I'll use this soon
-        private CompilationPhases replace(final CompilationPhase phase, final CompilationPhase newPhase) {
-            final LinkedList<CompilationPhase> list = new LinkedList<>();
-            for (final CompilationPhase p : phases) {
-                list.add(p == phase ? newPhase : p);
-            }
-            return new CompilationPhases(desc, list.toArray(new CompilationPhase[list.size()]));
-        }
-
-        private CompilationPhases addAfter(final CompilationPhase phase, final CompilationPhase newPhase) {
-            final LinkedList<CompilationPhase> list = new LinkedList<>();
-            for (final CompilationPhase p : phases) {
-                list.add(p);
-                if (p == phase) {
-                    list.add(newPhase);
-                }
-            }
-            return new CompilationPhases(desc, list.toArray(new CompilationPhase[list.size()]));
-        }
-
         boolean contains(final CompilationPhase phase) {
             return phases.contains(phase);
         }
@@ -284,7 +313,7 @@
         }
 
         boolean isRestOfCompilation() {
-            return this == COMPILE_ALL_RESTOF || this == COMPILE_FROM_BYTECODE_RESTOF;
+            return this == COMPILE_ALL_RESTOF || this == GENERATE_BYTECODE_AND_INSTALL_RESTOF || this == COMPILE_SERIALIZED_RESTOF;
         }
 
         String getDesc() {
@@ -749,6 +778,14 @@
         compileUnits.addAll(newUnits);
     }
 
+    void serializeAst(final FunctionNode fn) {
+        serializedAsts.put(fn.getId(), AstSerializer.serialize(fn));
+    }
+
+    byte[] removeSerializedAst(final int fnId) {
+        return serializedAsts.remove(fnId);
+    }
+
     CompileUnit findUnit(final long weight) {
         for (final CompileUnit unit : compileUnits) {
             if (unit.canHold(weight)) {
@@ -771,7 +808,10 @@
     }
 
     RecompilableScriptFunctionData getScriptFunctionData(final int functionId) {
-        return compiledFunction == null ? null : compiledFunction.getScriptFunctionData(functionId);
+        assert compiledFunction != null;
+        final RecompilableScriptFunctionData fn = compiledFunction.getScriptFunctionData(functionId);
+        assert fn != null : functionId;
+        return fn;
     }
 
     boolean isGlobalSymbol(final FunctionNode fn, final String name) {
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/FindScopeDepths.java
--- a/src/jdk/nashorn/internal/codegen/FindScopeDepths.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/FindScopeDepths.java	Mon Oct 20 12:06:36 2014 +0200
@@ -187,7 +187,6 @@
 
         if (compiler.isOnDemandCompilation()) {
             final RecompilableScriptFunctionData data = compiler.getScriptFunctionData(newFunctionNode.getId());
-            assert data != null : newFunctionNode.getName() + " lacks data";
             if (data.inDynamicContext()) {
                 log.fine("Reviving scriptfunction ", quote(name), " as defined in previous (now lost) dynamic scope.");
                 newFunctionNode = newFunctionNode.setInDynamicContext(lc);
@@ -202,7 +201,7 @@
 
         //create recompilable scriptfunctiondata
         final int fnId = newFunctionNode.getId();
-        final Map<Integer, RecompilableScriptFunctionData> nestedFunctions = fnIdToNestedFunctions.get(fnId);
+        final Map<Integer, RecompilableScriptFunctionData> nestedFunctions = fnIdToNestedFunctions.remove(fnId);
 
         assert nestedFunctions != null;
         // Generate the object class and property map in case this function is ever used as constructor
@@ -212,8 +211,8 @@
                 new AllocatorDescriptor(newFunctionNode.getThisProperties()),
                 nestedFunctions,
                 externalSymbolDepths.get(fnId),
-                internalSymbols.get(fnId)
-                );
+                internalSymbols.get(fnId),
+                compiler.removeSerializedAst(fnId));
 
         if (lc.getOutermostFunction() != newFunctionNode) {
             final FunctionNode parentFn = lc.getParentFunction(newFunctionNode);
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/LocalVariableTypesCalculator.java
--- a/src/jdk/nashorn/internal/codegen/LocalVariableTypesCalculator.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/LocalVariableTypesCalculator.java	Mon Oct 20 12:06:36 2014 +0200
@@ -72,7 +72,7 @@
 import jdk.nashorn.internal.ir.ReturnNode;
 import jdk.nashorn.internal.ir.RuntimeNode;
 import jdk.nashorn.internal.ir.RuntimeNode.Request;
-import jdk.nashorn.internal.ir.SplitNode;
+import jdk.nashorn.internal.ir.SplitReturn;
 import jdk.nashorn.internal.ir.Statement;
 import jdk.nashorn.internal.ir.SwitchNode;
 import jdk.nashorn.internal.ir.Symbol;
@@ -361,10 +361,6 @@
     // Synthetic return node that we must insert at the end of the function if it's end is reachable.
     private ReturnNode syntheticReturn;
 
-    // Topmost current split node (if any)
-    private SplitNode topSplit;
-    private boolean split;
-
     private boolean alreadyEnteredTopLevelFunction;
 
     // LvarType and conversion information gathered during the top-down pass; applied to nodes in the bottom-up pass.
@@ -477,22 +473,7 @@
             return false;
         }
         final BreakableNode target = jump.getTarget(lc);
-        return splitAwareJumpToLabel(jump, target, jump.getTargetLabel(target));
-    }
-
-    private boolean splitAwareJumpToLabel(final JumpStatement jumpStatement, final BreakableNode target, final Label targetLabel) {
-        final JoinPredecessor jumpOrigin;
-        if(topSplit != null && lc.isExternalTarget(topSplit, target)) {
-            // If the jump target is outside the topmost split node, then we'll create a synthetic jump origin in the
-            // split node.
-            jumpOrigin = new JoinPredecessorExpression();
-            topSplit.addJump(jumpOrigin, targetLabel);
-        } else {
-            // Otherwise, the original jump statement is the jump origin
-            jumpOrigin = jumpStatement;
-        }
-
-        jumpToLabel(jumpOrigin, targetLabel, getBreakTargetTypes(target));
+        jumpToLabel(jump, jump.getTargetLabel(target), getBreakTargetTypes(target));
         doesNotContinueSequentially();
         return false;
     }
@@ -703,18 +684,9 @@
     }
 
     @Override
-    public boolean enterSplitNode(final SplitNode splitNode) {
-        if(!reachable) {
-            return false;
-        }
-        // Need to visit inside of split nodes. While it's true that they don't have local variables, we need to visit
-        // breaks, continues, and returns in them.
-        if(topSplit == null) {
-            topSplit = splitNode;
-        }
-        split = true;
-        setType(getCompilerConstantSymbol(lc.getCurrentFunction(), CompilerConstants.RETURN), LvarType.UNDEFINED);
-        return true;
+    public boolean enterSplitReturn(final SplitReturn splitReturn) {
+        doesNotContinueSequentially();
+        return false;
     }
 
     @Override
@@ -1116,15 +1088,6 @@
         if(returnType.isUnknown()) {
             returnType = Type.OBJECT;
         }
-
-        if(split) {
-            // If the function is split, the ":return" symbol is used and needs a slot. Note we can't mark the return
-            // symbol as used in enterSplitNode, as we don't know the final return type of the function earlier than
-            // here.
-            final Symbol retSymbol = getCompilerConstantSymbol(lc.getCurrentFunction(), CompilerConstants.RETURN);
-            retSymbol.setHasSlotFor(returnType);
-            retSymbol.setNeedsSlot(true);
-        }
     }
 
     private void createSyntheticReturn(final Block body) {
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/Lower.java
--- a/src/jdk/nashorn/internal/codegen/Lower.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/Lower.java	Mon Oct 20 12:06:36 2014 +0200
@@ -352,8 +352,6 @@
     private Node spliceFinally(final TryNode tryNode, final List<ThrowNode> rethrows, final Block finallyBody) {
         assert tryNode.getFinallyBody() == null;
 
-        final LexicalContext lowerLc = lc;
-
         final TryNode newTryNode = (TryNode)tryNode.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
             final List<Node> insideTry = new ArrayList<>();
 
@@ -406,7 +404,6 @@
                     //still in the try block, store it in a result value and return it afterwards
                     resultNode = new IdentNode(Lower.this.compilerConstant(RETURN));
                     newStatements.add(new ExpressionStatement(returnNode.getLineNumber(), returnNode.getToken(), returnNode.getFinish(), new BinaryNode(Token.recast(returnNode.getToken(), TokenType.ASSIGN), resultNode, expr)));
-                    lowerLc.setFlag(lowerLc.getCurrentFunction(), FunctionNode.USES_RETURN_SYMBOL);
                 } else {
                     resultNode = null;
                 }
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/MethodEmitter.java
--- a/src/jdk/nashorn/internal/codegen/MethodEmitter.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/MethodEmitter.java	Mon Oct 20 12:06:36 2014 +0200
@@ -71,6 +71,7 @@
 import static jdk.nashorn.internal.codegen.ObjectClassGenerator.PRIMITIVE_FIELD_TYPE;
 import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.CALLSITE_OPTIMISTIC;
 import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.CALLSITE_PROGRAM_POINT_SHIFT;
+
 import java.io.PrintStream;
 import java.lang.reflect.Array;
 import java.util.Collection;
@@ -88,11 +89,9 @@
 import jdk.nashorn.internal.codegen.types.BitwiseType;
 import jdk.nashorn.internal.codegen.types.NumericType;
 import jdk.nashorn.internal.codegen.types.Type;
-import jdk.nashorn.internal.ir.BreakableNode;
 import jdk.nashorn.internal.ir.FunctionNode;
 import jdk.nashorn.internal.ir.IdentNode;
 import jdk.nashorn.internal.ir.JoinPredecessor;
-import jdk.nashorn.internal.ir.LexicalContext;
 import jdk.nashorn.internal.ir.LiteralNode;
 import jdk.nashorn.internal.ir.LocalVariableConversion;
 import jdk.nashorn.internal.ir.RuntimeNode;
@@ -1664,19 +1663,6 @@
     }
 
     /**
-     * Goto, possibly when splitting is taking place. If
-     * a splitNode exists, we need to handle the case that the
-     * jump target is another method
-     *
-     * @param label destination label
-     * @param targetNode the node to which the destination label belongs (the label is normally a break or continue
-     * label)
-     */
-    void splitAwareGoto(final LexicalContext lc, final Label label, final BreakableNode targetNode) {
-        _goto(label);
-    }
-
-    /**
      * Perform a comparison of two number types that are popped from the stack
      *
      * @param isCmpG is this a dcmpg semantic, false if it's a dcmpl semantic
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/OptimisticTypesCalculator.java
--- a/src/jdk/nashorn/internal/codegen/OptimisticTypesCalculator.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/OptimisticTypesCalculator.java	Mon Oct 20 12:06:36 2014 +0200
@@ -30,7 +30,6 @@
 import java.util.ArrayDeque;
 import java.util.BitSet;
 import java.util.Deque;
-import jdk.nashorn.internal.IntDeque;
 import jdk.nashorn.internal.ir.AccessNode;
 import jdk.nashorn.internal.ir.BinaryNode;
 import jdk.nashorn.internal.ir.CallNode;
@@ -49,7 +48,6 @@
 import jdk.nashorn.internal.ir.Node;
 import jdk.nashorn.internal.ir.Optimistic;
 import jdk.nashorn.internal.ir.PropertyNode;
-import jdk.nashorn.internal.ir.SplitNode;
 import jdk.nashorn.internal.ir.Symbol;
 import jdk.nashorn.internal.ir.TernaryNode;
 import jdk.nashorn.internal.ir.UnaryNode;
@@ -70,8 +68,6 @@
 
     // Per-function bit set of program points that must never be optimistic.
     final Deque<BitSet> neverOptimistic = new ArrayDeque<>();
-    // Per-function depth of split nodes
-    final IntDeque splitDepth = new IntDeque();
 
     OptimisticTypesCalculator(final Compiler compiler) {
         super(new LexicalContext());
@@ -155,7 +151,6 @@
             return false;
         }
         neverOptimistic.push(new BitSet());
-        splitDepth.push(0);
         return true;
     }
 
@@ -190,19 +185,6 @@
     }
 
     @Override
-    public boolean enterSplitNode(final SplitNode splitNode) {
-        splitDepth.getAndIncrement();
-        return true;
-    }
-
-    @Override
-    public Node leaveSplitNode(final SplitNode splitNode) {
-        final int depth = splitDepth.decrementAndGet();
-        assert depth >= 0;
-        return splitNode;
-    }
-
-    @Override
     public boolean enterVarNode(final VarNode varNode) {
         tagNeverOptimistic(varNode.getName());
         return true;
@@ -226,16 +208,11 @@
     @Override
     public Node leaveFunctionNode(final FunctionNode functionNode) {
         neverOptimistic.pop();
-        final int lastSplitDepth = splitDepth.pop();
-        assert lastSplitDepth == 0;
         return functionNode.setState(lc, CompilationState.OPTIMISTIC_TYPES_ASSIGNED);
     }
 
     @Override
     public Node leaveIdentNode(final IdentNode identNode) {
-        if(inSplitNode()) {
-            return identNode;
-        }
         final Symbol symbol = identNode.getSymbol();
         if(symbol == null) {
             assert identNode.isPropertyName();
@@ -256,7 +233,7 @@
 
     private Expression leaveOptimistic(final Optimistic opt) {
         final int pp = opt.getProgramPoint();
-        if(isValid(pp) && !inSplitNode() && !neverOptimistic.peek().get(pp)) {
+        if(isValid(pp) && !neverOptimistic.peek().get(pp)) {
             return (Expression)opt.setType(compiler.getOptimisticType(opt));
         }
         return (Expression)opt;
@@ -277,8 +254,4 @@
             tagNeverOptimistic(test.getExpression());
         }
     }
-
-    private boolean inSplitNode() {
-        return splitDepth.peek() > 0;
-    }
 }
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/ProgramPoints.java
--- a/src/jdk/nashorn/internal/codegen/ProgramPoints.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/codegen/ProgramPoints.java	Mon Oct 20 12:06:36 2014 +0200
@@ -85,7 +85,7 @@
 
     @Override
     public boolean enterVarNode(final VarNode varNode) {
-        noProgramPoint.add(varNode.getAssignmentDest());
+        noProgramPoint.add(varNode.getName());
         return true;
     }
 
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/ReplaceCompileUnits.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/codegen/ReplaceCompileUnits.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.nashorn.internal.codegen;
+
+import java.util.ArrayList;
+import java.util.List;
+import jdk.nashorn.internal.ir.CompileUnitHolder;
+import jdk.nashorn.internal.ir.FunctionNode;
+import jdk.nashorn.internal.ir.FunctionNode.CompilationState;
+import jdk.nashorn.internal.ir.LexicalContext;
+import jdk.nashorn.internal.ir.LiteralNode;
+import jdk.nashorn.internal.ir.LiteralNode.ArrayLiteralNode;
+import jdk.nashorn.internal.ir.LiteralNode.ArrayLiteralNode.ArrayUnit;
+import jdk.nashorn.internal.ir.Node;
+import jdk.nashorn.internal.ir.visitor.NodeVisitor;
+
+/**
+ * Base class for a node visitor that replaces {@link CompileUnit}s in {@link CompileUnitHolder}s.
+ */
+abstract class ReplaceCompileUnits extends NodeVisitor<LexicalContext> {
+    ReplaceCompileUnits() {
+        super(new LexicalContext());
+    }
+
+    /**
+     * Override to provide a replacement for an old compile unit.
+     * @param oldUnit the old compile unit to replace
+     * @return the compile unit's replacement.
+     */
+    abstract CompileUnit getReplacement(final CompileUnit oldUnit);
+
+    CompileUnit getExistingReplacement(final CompileUnitHolder node) {
+        final CompileUnit oldUnit = node.getCompileUnit();
+        assert oldUnit != null;
+
+        final CompileUnit newUnit = getReplacement(oldUnit);
+        assert newUnit != null;
+
+        return newUnit;
+    }
+
+    @Override
+    public Node leaveFunctionNode(final FunctionNode node) {
+        return node.setCompileUnit(lc, getExistingReplacement(node)).setState(lc, CompilationState.COMPILE_UNITS_REUSED);
+    }
+
+    @Override
+    public Node leaveLiteralNode(final LiteralNode<?> node) {
+        if (node instanceof ArrayLiteralNode) {
+            final ArrayLiteralNode aln = (ArrayLiteralNode)node;
+            if (aln.getUnits() == null) {
+                return node;
+            }
+            final List<ArrayUnit> newArrayUnits = new ArrayList<>();
+            for (final ArrayUnit au : aln.getUnits()) {
+                newArrayUnits.add(new ArrayUnit(getExistingReplacement(au), au.getLo(), au.getHi()));
+            }
+            return aln.setUnits(lc, newArrayUnits);
+        }
+        return node;
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/SplitIntoFunctions.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/codegen/SplitIntoFunctions.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,446 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.nashorn.internal.codegen;
+
+import static jdk.nashorn.internal.ir.Node.NO_FINISH;
+import static jdk.nashorn.internal.ir.Node.NO_LINE_NUMBER;
+import static jdk.nashorn.internal.ir.Node.NO_TOKEN;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Deque;
+import java.util.List;
+import java.util.Objects;
+import jdk.nashorn.internal.ir.AccessNode;
+import jdk.nashorn.internal.ir.BinaryNode;
+import jdk.nashorn.internal.ir.Block;
+import jdk.nashorn.internal.ir.BlockLexicalContext;
+import jdk.nashorn.internal.ir.BreakNode;
+import jdk.nashorn.internal.ir.CallNode;
+import jdk.nashorn.internal.ir.CaseNode;
+import jdk.nashorn.internal.ir.ContinueNode;
+import jdk.nashorn.internal.ir.Expression;
+import jdk.nashorn.internal.ir.ExpressionStatement;
+import jdk.nashorn.internal.ir.FunctionNode;
+import jdk.nashorn.internal.ir.GetSplitState;
+import jdk.nashorn.internal.ir.IdentNode;
+import jdk.nashorn.internal.ir.IfNode;
+import jdk.nashorn.internal.ir.JumpStatement;
+import jdk.nashorn.internal.ir.LiteralNode;
+import jdk.nashorn.internal.ir.Node;
+import jdk.nashorn.internal.ir.ReturnNode;
+import jdk.nashorn.internal.ir.SetSplitState;
+import jdk.nashorn.internal.ir.SplitNode;
+import jdk.nashorn.internal.ir.SplitReturn;
+import jdk.nashorn.internal.ir.Statement;
+import jdk.nashorn.internal.ir.SwitchNode;
+import jdk.nashorn.internal.ir.VarNode;
+import jdk.nashorn.internal.ir.visitor.NodeVisitor;
+import jdk.nashorn.internal.parser.Token;
+import jdk.nashorn.internal.parser.TokenType;
+
+/**
+ * A node visitor that replaces {@link SplitNode}s with anonymous function invocations and some additional constructs
+ * to support control flow across splits. By using this transformation, split functions are translated into ordinary
+ * JavaScript functions with nested anonymous functions. The transformations however introduce several AST nodes that
+ * have no JavaScript source representations ({@link GetSplitState}, {@link SetSplitState}, and {@link SplitReturn}),
+ * and therefore such function is no longer reparseable from its source. For that reason, split functions and their
+ * fragments are serialized in-memory and deserialized when they need to be recompiled either for deoptimization or
+ * for type specialization.
+ * NOTE: all {@code leave*()} methods for statements are returning their input nodes. That way, they will not mutate
+ * the original statement list in the block containing the statement, which is fine, as it'll be replaced by the
+ * lexical context when the block is left. If we returned something else (e.g. null), we'd cause a mutation in the
+ * enclosing block's statement list that is otherwise overwritten later anyway.
+ */
+final class SplitIntoFunctions extends NodeVisitor<BlockLexicalContext> {
+    private static final int FALLTHROUGH_STATE = -1;
+    private static final int RETURN_STATE = 0;
+    private static final int BREAK_STATE = 1;
+    private static final int FIRST_JUMP_STATE = 2;
+
+    private static final String THIS_NAME = CompilerConstants.THIS.symbolName();
+    private static final String RETURN_NAME = CompilerConstants.RETURN.symbolName();
+    // Used as the name of the formal parameter for passing the current value of :return symbol into a split fragment.
+    private static final String RETURN_PARAM_NAME = RETURN_NAME + "-in";
+
+    private final Deque<FunctionState> functionStates = new ArrayDeque<>();
+    private final Deque<SplitState> splitStates = new ArrayDeque<>();
+    private final Namespace namespace;
+
+    private boolean artificialBlock = false;
+
+    // -1 is program; we need to use negative ones
+    private int nextFunctionId = -2;
+
+    public SplitIntoFunctions(final Compiler compiler) {
+        super(new BlockLexicalContext() {
+            @Override
+            protected Block afterSetStatements(Block block) {
+                for(Statement stmt: block.getStatements()) {
+                    assert !(stmt instanceof SplitNode);
+                }
+                return block;
+            }
+        });
+        namespace = new Namespace(compiler.getScriptEnvironment().getNamespace());
+    }
+
+    @Override
+    public boolean enterFunctionNode(final FunctionNode functionNode) {
+        functionStates.push(new FunctionState(functionNode));
+        return true;
+    }
+
+    @Override
+    public Node leaveFunctionNode(final FunctionNode functionNode) {
+        functionStates.pop();
+        return functionNode;
+    }
+
+    @Override
+    protected Node leaveDefault(final Node node) {
+        if (node instanceof Statement) {
+            appendStatement((Statement)node);
+        }
+        return node;
+    }
+
+    @Override
+    public boolean enterSplitNode(final SplitNode splitNode) {
+        getCurrentFunctionState().splitDepth++;
+        splitStates.push(new SplitState(splitNode));
+        return true;
+    }
+
+    @Override
+    public Node leaveSplitNode(final SplitNode splitNode) {
+        // Replace the split node with an anonymous function expression call.
+
+        final FunctionState fnState = getCurrentFunctionState();
+
+        final String name = splitNode.getName();
+        Block body = splitNode.getBody();
+        final int firstLineNumber = body.getFirstStatementLineNumber();
+        final long token = body.getToken();
+        final int finish = body.getFinish();
+
+        final FunctionNode originalFn = fnState.fn;
+        assert originalFn == lc.getCurrentFunction();
+        final boolean isProgram = originalFn.isProgram();
+
+        // Change SplitNode({...}) into "function () { ... }", or "function (:return-in) () { ... }" (for program)
+        final long newFnToken = Token.toDesc(TokenType.FUNCTION, nextFunctionId--, 0);
+        final FunctionNode fn = new FunctionNode(
+                originalFn.getSource(),
+                body.getFirstStatementLineNumber(),
+                newFnToken,
+                finish,
+                NO_TOKEN,
+                namespace,
+                createIdent(name),
+                originalFn.getName() + "$" + name,
+                isProgram ? Collections.singletonList(createReturnParamIdent()) : Collections.<IdentNode>emptyList(),
+                FunctionNode.Kind.NORMAL,
+                // We only need IS_SPLIT conservatively, in case it contains any array units so that we force
+                // the :callee's existence, to force :scope to never be in a slot lower than 2. This is actually
+                // quite a horrible hack to do with CodeGenerator.fixScopeSlot not trampling other parameters
+                // and should go away once we no longer have array unit handling in codegen. Note however that
+                // we still use IS_SPLIT as the criteria in CompilationPhase.SERIALIZE_SPLIT_PHASE.
+                FunctionNode.IS_ANONYMOUS | FunctionNode.USES_ANCESTOR_SCOPE | FunctionNode.IS_SPLIT
+        )
+        .setBody(lc, body)
+        .setCompileUnit(lc, splitNode.getCompileUnit())
+        .copyCompilationState(lc, originalFn);
+
+        // Call the function:
+        //     either "(function () { ... }).call(this)"
+        //     or     "(function (:return-in) { ... }).call(this, :return)"
+        // NOTE: Function.call() has optimized linking that basically does a pass-through to the function being invoked.
+        // NOTE: CompilationPhase.PROGRAM_POINT_PHASE happens after this, so these calls are subject to optimistic
+        // assumptions on their return value (when they return a value), as they should be.
+        final IdentNode thisIdent = createIdent(THIS_NAME);
+        final CallNode callNode = new CallNode(firstLineNumber, token, finish, new AccessNode(NO_TOKEN, NO_FINISH, fn, "call"),
+                isProgram ? Arrays.<Expression>asList(thisIdent, createReturnIdent())
+                          : Collections.<Expression>singletonList(thisIdent),
+                false);
+
+        final SplitState splitState = splitStates.pop();
+        fnState.splitDepth--;
+
+        final Expression callWithReturn;
+        final boolean hasReturn = splitState.hasReturn;
+        if (hasReturn && fnState.splitDepth > 0) {
+            final SplitState parentSplit = splitStates.peek();
+            if (parentSplit != null) {
+                // Propagate hasReturn to parent split
+                parentSplit.hasReturn = true;
+            }
+        }
+        if (hasReturn || isProgram) {
+            // capture return value: ":return = (function () { ... })();"
+            callWithReturn = new BinaryNode(Token.recast(token, TokenType.ASSIGN), createReturnIdent(), callNode);
+        } else {
+            // no return value, just call : "(function () { ... })();"
+            callWithReturn = callNode;
+        }
+        appendStatement(new ExpressionStatement(firstLineNumber, token, finish, callWithReturn));
+
+        Statement splitStateHandler;
+
+        final List<JumpStatement> jumpStatements = splitState.jumpStatements;
+        final int jumpCount = jumpStatements.size();
+        // There are jumps (breaks or continues) that need to be propagated outside the split node. We need to
+        // set up a switch statement for them:
+        // switch(:scope.getScopeState()) { ... }
+        if (jumpCount > 0) {
+            final List<CaseNode> cases = new ArrayList<>(jumpCount + (hasReturn ? 1 : 0));
+            if (hasReturn) {
+                // If the split node also contained a return, we'll slip it as a case in the switch statement
+                addCase(cases, RETURN_STATE, createReturnFromSplit());
+            }
+            int i = FIRST_JUMP_STATE;
+            for (final JumpStatement jump: jumpStatements) {
+                addCase(cases, i++, enblockAndVisit(jump));
+            }
+            splitStateHandler = new SwitchNode(NO_LINE_NUMBER, token, finish, GetSplitState.INSTANCE, cases, null);
+        } else {
+            splitStateHandler = null;
+        }
+
+        // As the switch statement itself is breakable, an unlabelled break can't be in the switch statement,
+        // so we need to test for it separately.
+        if (splitState.hasBreak) {
+            // if(:scope.getScopeState() == Scope.BREAK) { break; }
+            splitStateHandler = makeIfStateEquals(firstLineNumber, token, finish, BREAK_STATE,
+                    enblockAndVisit(new BreakNode(NO_LINE_NUMBER, token, finish, null)), splitStateHandler);
+        }
+
+        // Finally, if the split node had a return statement, but there were no external jumps, we didn't have
+        // the switch statement to handle the return, so we need a separate if for it.
+        if (hasReturn && jumpCount == 0) {
+            // if (:scope.getScopeState() == Scope.RETURN) { return :return; }
+            splitStateHandler = makeIfStateEquals(NO_LINE_NUMBER, token, finish, RETURN_STATE,
+                    createReturnFromSplit(), splitStateHandler);
+        }
+
+        if (splitStateHandler != null) {
+            appendStatement(splitStateHandler);
+        }
+
+        return splitNode;
+    }
+
+    private static void addCase(final List<CaseNode> cases, final int i, final Block body) {
+        cases.add(new CaseNode(NO_TOKEN, NO_FINISH, intLiteral(i), body));
+    }
+
+    private static LiteralNode<Number> intLiteral(final int i) {
+        return LiteralNode.newInstance(NO_TOKEN, NO_FINISH, i);
+    }
+
+    private static Block createReturnFromSplit() {
+        return new Block(NO_TOKEN, NO_FINISH, createReturnReturn());
+    }
+
+    private static ReturnNode createReturnReturn() {
+        return new ReturnNode(NO_LINE_NUMBER, NO_TOKEN, NO_FINISH, createReturnIdent());
+    }
+
+    private static IdentNode createReturnIdent() {
+        return createIdent(RETURN_NAME);
+    }
+
+    private static IdentNode createReturnParamIdent() {
+        return createIdent(RETURN_PARAM_NAME);
+    }
+
+    private static IdentNode createIdent(final String name) {
+        return new IdentNode(NO_TOKEN, NO_FINISH, name);
+    }
+
+    private Block enblockAndVisit(final JumpStatement jump) {
+        artificialBlock = true;
+        final Block block = (Block)new Block(NO_TOKEN, NO_FINISH, jump).accept(this);
+        artificialBlock = false;
+        return block;
+    }
+
+    private static IfNode makeIfStateEquals(final int lineNumber, final long token, final int finish,
+            final int value, final Block pass, final Statement fail) {
+        return new IfNode(lineNumber, token, finish,
+                new BinaryNode(Token.recast(token, TokenType.EQ_STRICT),
+                        GetSplitState.INSTANCE, intLiteral(value)),
+                pass,
+                fail == null ? null : new Block(NO_TOKEN, NO_FINISH, fail));
+    }
+
+    @Override
+    public boolean enterVarNode(VarNode varNode) {
+        if (!inSplitNode()) {
+            return super.enterVarNode(varNode);
+        }
+        assert !varNode.isBlockScoped(); //TODO: we must handle these too, but we currently don't
+
+        final Expression init = varNode.getInit();
+        if (varNode.isAnonymousFunctionDeclaration()) {
+            // We ain't moving anonymous function declarations.
+            return super.enterVarNode(varNode);
+        }
+
+        // Move a declaration-only var statement to the top of the outermost function.
+        getCurrentFunctionState().varStatements.add(varNode.setInit(null));
+        // If it had an initializer, replace it with an assignment expression statement. Note that "var" is a
+        // statement, so it doesn't contribute to :return of the programs, therefore we are _not_ adding a
+        // ":return = ..." assignment around the original assignment.
+        if (init != null) {
+            final long token = Token.recast(varNode.getToken(), TokenType.ASSIGN);
+            new ExpressionStatement(varNode.getLineNumber(), token, varNode.getFinish(),
+                    new BinaryNode(token, varNode.getName(), varNode.getInit())).accept(this);
+        }
+
+        return false;
+    }
+
+    @Override
+    public Node leaveBlock(final Block block) {
+        if (!artificialBlock) {
+            if (lc.isFunctionBody()) {
+                // Prepend declaration-only var statements to the top of the statement list.
+                lc.prependStatements(getCurrentFunctionState().varStatements);
+            } else if (lc.isSplitBody()) {
+                appendSplitReturn(FALLTHROUGH_STATE, NO_LINE_NUMBER);
+                if (getCurrentFunctionState().fn.isProgram()) {
+                    // If we're splitting the program, make sure every shard ends with "return :return" and
+                    // begins with ":return = :return-in;".
+                    lc.prependStatement(new ExpressionStatement(NO_LINE_NUMBER, NO_TOKEN, NO_FINISH,
+                            new BinaryNode(Token.toDesc(TokenType.ASSIGN, 0, 0), createReturnIdent(), createReturnParamIdent())));
+                }
+            }
+        }
+        return block;
+    }
+
+    @Override
+    public Node leaveBreakNode(final BreakNode breakNode) {
+        return leaveJumpNode(breakNode);
+    }
+
+    @Override
+    public Node leaveContinueNode(final ContinueNode continueNode) {
+        return leaveJumpNode(continueNode);
+    }
+
+    private JumpStatement leaveJumpNode(final JumpStatement jump) {
+        if (inSplitNode()) {
+            final SplitState splitState = getCurrentSplitState();
+            final SplitNode splitNode = splitState.splitNode;
+            if (lc.isExternalTarget(splitNode, jump.getTarget(lc))) {
+                appendSplitReturn(splitState.getSplitStateIndex(jump), jump.getLineNumber());
+                return jump;
+            }
+        }
+        appendStatement(jump);
+        return jump;
+    }
+
+    private void appendSplitReturn(final int splitState, final int lineNumber) {
+        appendStatement(new SetSplitState(splitState, lineNumber));
+        if (getCurrentFunctionState().fn.isProgram()) {
+            // If we're splitting the program, make sure every fragment passes back :return
+            appendStatement(createReturnReturn());
+        } else {
+            appendStatement(SplitReturn.INSTANCE);
+        }
+    }
+
+    @Override
+    public Node leaveReturnNode(final ReturnNode returnNode) {
+        if(inSplitNode()) {
+            appendStatement(new SetSplitState(RETURN_STATE, returnNode.getLineNumber()));
+            getCurrentSplitState().hasReturn = true;
+        }
+        appendStatement(returnNode);
+        return returnNode;
+    }
+
+    private void appendStatement(final Statement statement) {
+        lc.appendStatement(statement);
+    }
+
+    private boolean inSplitNode() {
+        return getCurrentFunctionState().splitDepth > 0;
+    }
+
+    private FunctionState getCurrentFunctionState() {
+        return functionStates.peek();
+    }
+
+    private SplitState getCurrentSplitState() {
+        return splitStates.peek();
+    }
+
+    private static class FunctionState {
+        final FunctionNode fn;
+        final List<Statement> varStatements = new ArrayList<>();
+        int splitDepth;
+
+        FunctionState(final FunctionNode fn) {
+            this.fn = fn;
+        }
+    }
+
+    private static class SplitState {
+        final SplitNode splitNode;
+        boolean hasReturn;
+        boolean hasBreak;
+
+        final List<JumpStatement> jumpStatements = new ArrayList<>();
+
+        int getSplitStateIndex(final JumpStatement jump) {
+            if (jump instanceof BreakNode && jump.getLabelName() == null) {
+                // Unlabelled break is a special case
+                hasBreak = true;
+                return BREAK_STATE;
+            }
+
+            int i = 0;
+            for(final JumpStatement exJump: jumpStatements) {
+                if (jump.getClass() == exJump.getClass() && Objects.equals(jump.getLabelName(), exJump.getLabelName())) {
+                    return i + FIRST_JUMP_STATE;
+                }
+                ++i;
+            }
+            jumpStatements.add(jump);
+            return i + FIRST_JUMP_STATE;
+        }
+
+        SplitState(final SplitNode splitNode) {
+            this.splitNode = splitNode;
+        }
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/codegen/SplitMethodEmitter.java
--- a/src/jdk/nashorn/internal/codegen/SplitMethodEmitter.java	Fri Oct 17 14:24:26 2014 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,102 +0,0 @@
-/*
- * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-package jdk.nashorn.internal.codegen;
-
-import java.util.ArrayList;
-import java.util.List;
-import jdk.internal.org.objectweb.asm.MethodVisitor;
-import jdk.nashorn.internal.codegen.types.Type;
-import jdk.nashorn.internal.ir.BreakableNode;
-import jdk.nashorn.internal.ir.LexicalContext;
-import jdk.nashorn.internal.ir.SplitNode;
-
-/**
- * Emitter used for splitting methods. Needs to keep track of if there are jump targets
- * outside the current split node. All external jump targets encountered at method
- * emission are logged, and {@code CodeGenerator#leaveSplitNode(SplitNode)} creates
- * an appropriate jump table when the SplitNode has been iterated through
- */
-public class SplitMethodEmitter extends MethodEmitter {
-
-    private final SplitNode splitNode;
-
-    private final List<Label> externalTargets = new ArrayList<>();
-    /**
-     * In addition to external target labels, we need to track the target breakables too as the code generator needs to
-     * be able to correctly pop the scopes to the target, see {@link CodeGenerator#leaveSplitNode(SplitNode)}. Note that
-     * this is only used within CodeGenerator, which doesn't mutate the AST, so keeping pointers to other nodes is not
-     * incorrect.
-     */
-    private final List<BreakableNode> externalTargetNodes = new ArrayList<>();
-
-    SplitMethodEmitter(final ClassEmitter classEmitter, final MethodVisitor mv, final SplitNode splitNode) {
-        super(classEmitter, mv);
-        this.splitNode = splitNode;
-    }
-
-    @Override
-    void splitAwareGoto(final LexicalContext lc, final Label label, final BreakableNode targetNode) {
-        assert splitNode != null;
-        final int index = findExternalTarget(lc, label, targetNode);
-        if (index >= 0) {
-            setSplitState(index + 1); // 0 is ordinary return
-            final Type retType = functionNode.getReturnType();
-            loadUndefined(retType);
-            _return(retType);
-        } else {
-            super.splitAwareGoto(lc, label, targetNode);
-        }
-    }
-
-    private int findExternalTarget(final LexicalContext lc, final Label label, final BreakableNode targetNode) {
-        final int index = externalTargets.indexOf(label);
-
-        if (index >= 0) {
-            return index;
-        }
-
-        if (lc.isExternalTarget(splitNode, targetNode)) {
-            externalTargets.add(label);
-            externalTargetNodes.add(targetNode);
-            return externalTargets.size() - 1;
-        }
-        return -1;
-    }
-
-    @Override
-    MethodEmitter registerReturn() {
-        setHasReturn();
-        return setSplitState(0);
-    }
-
-    final List<Label> getExternalTargets() {
-        return externalTargets;
-    }
-
-    final List<BreakableNode> getExternalTargetNodes() {
-        return externalTargetNodes;
-    }
-}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/BlockLexicalContext.java
--- a/src/jdk/nashorn/internal/ir/BlockLexicalContext.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/BlockLexicalContext.java	Mon Oct 20 12:06:36 2014 +0200
@@ -109,6 +109,16 @@
     }
 
     /**
+     * Prepend a list of statement to the block being generated
+     * @param statements a list of statements to prepend
+     */
+    public void prependStatements(final List<Statement> statements) {
+        assert statements != null;
+        sstack.peek().addAll(0, statements);
+    }
+
+
+    /**
      * Get the last statement that was emitted into a block
      * @return the last statement emitted
      */
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/FunctionNode.java
--- a/src/jdk/nashorn/internal/ir/FunctionNode.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/FunctionNode.java	Mon Oct 20 12:06:36 2014 +0200
@@ -109,7 +109,7 @@
     }
 
     /** Source of entity. */
-    private final Source source;
+    private transient final Source source;
 
     /**
      * Opaque object representing parser state at the end of the function. Used when reparsing outer functions
@@ -143,7 +143,7 @@
     private final long lastToken;
 
     /** Method's namespace. */
-    private final Namespace namespace;
+    private transient final Namespace namespace;
 
     /** Current compilation state */
     @Ignore
@@ -209,31 +209,23 @@
     /** Are we vararg, but do we just pass the arguments along to apply or call */
     public static final int HAS_APPLY_TO_CALL_SPECIALIZATION = 1 << 12;
 
-    /** Does this function explicitly use the {@link CompilerConstants#RETURN} symbol? Some functions are known to
-     * always use the return symbol, namely a function that is a program (as it must track its last executed expression
-     * statement's value) as well as functions that are split (to communicate return values from inner to outer
-     * partitions). Other functions normally don't use the return symbol (so we optimize away its slot), except in some
-     * very special cases, e.g. when containing a return statement in a finally block. These special cases set this
-     * flag. */
-    public static final int USES_RETURN_SYMBOL = 1 << 13;
-
     /**
      * Is this function the top-level program?
      */
-    public static final int IS_PROGRAM = 1 << 14;
+    public static final int IS_PROGRAM = 1 << 13;
 
     /**
      * Flag indicating whether this function uses the local variable symbol for itself. Only named function expressions
      * can have this flag set if they reference themselves (e.g. "(function f() { return f })". Declared functions will
      * use the symbol in their parent scope instead when they reference themselves by name.
      */
-    public static final int USES_SELF_SYMBOL = 1 << 15;
+    public static final int USES_SELF_SYMBOL = 1 << 14;
 
     /** Does this function use the "this" keyword? */
-    public static final int USES_THIS = 1 << 16;
+    public static final int USES_THIS = 1 << 15;
 
     /** Is this declared in a dynamic context */
-    public static final int IN_DYNAMIC_CONTEXT = 1 << 17;
+    public static final int IN_DYNAMIC_CONTEXT = 1 << 16;
 
     /**
      * The following flags are derived from directive comments within this function.
@@ -241,28 +233,28 @@
      */
 
     /** parser, print parse tree */
-    public static final int IS_PRINT_PARSE       = 1 << 18;
+    public static final int IS_PRINT_PARSE       = 1 << 17;
     /** parser, print lower parse tree */
-    public static final int IS_PRINT_LOWER_PARSE = 1 << 19;
+    public static final int IS_PRINT_LOWER_PARSE = 1 << 18;
     /** parser, print AST */
-    public static final int IS_PRINT_AST         = 1 << 20;
+    public static final int IS_PRINT_AST         = 1 << 19;
     /** parser, print lower AST */
-    public static final int IS_PRINT_LOWER_AST   = 1 << 21;
+    public static final int IS_PRINT_LOWER_AST   = 1 << 20;
     /** parser, print symbols */
-    public static final int IS_PRINT_SYMBOLS     = 1 << 22;
+    public static final int IS_PRINT_SYMBOLS     = 1 << 21;
 
     // callsite tracing, profiling within this function
     /** profile callsites in this function? */
-    public static final int IS_PROFILE         = 1 << 23;
+    public static final int IS_PROFILE         = 1 << 22;
 
     /** trace callsite enterexit in this function? */
-    public static final int IS_TRACE_ENTEREXIT = 1 << 24;
+    public static final int IS_TRACE_ENTEREXIT = 1 << 23;
 
     /** trace callsite misses in this function? */
-    public static final int IS_TRACE_MISSES    = 1 << 25;
+    public static final int IS_TRACE_MISSES    = 1 << 24;
 
     /** trace callsite values in this function? */
-    public static final int IS_TRACE_VALUES    = 1 << 26;
+    public static final int IS_TRACE_VALUES    = 1 << 25;
 
     /**
      * Whether this function needs the callee {@link ScriptFunction} instance passed to its code as a
@@ -270,7 +262,7 @@
      * Rather, it is always calculated (see {@link #needsCallee()}). {@link RecompilableScriptFunctionData}
      * will, however, cache the value of this flag.
      */
-    public static final int NEEDS_CALLEE       = 1 << 27;
+    public static final int NEEDS_CALLEE       = 1 << 26;
 
     /** extension callsite flags mask */
     public static final int EXTENSION_CALLSITE_FLAGS = IS_PRINT_PARSE |
@@ -287,8 +279,8 @@
     /** Does this function potentially need "arguments"? Note that this is not a full test, as further negative check of REDEFINES_ARGS is needed. */
     private static final int MAYBE_NEEDS_ARGUMENTS = USES_ARGUMENTS | HAS_EVAL;
 
-    /** Does this function need the parent scope? It needs it if either it or its descendants use variables from it, or have a deep eval. */
-    private static final int NEEDS_PARENT_SCOPE = USES_ANCESTOR_SCOPE | HAS_DEEP_EVAL;
+    /** Does this function need the parent scope? It needs it if either it or its descendants use variables from it, or have a deep eval, or it's the program. */
+    public static final int NEEDS_PARENT_SCOPE = USES_ANCESTOR_SCOPE | HAS_DEEP_EVAL | IS_PROGRAM;
 
     /** What is the return type of this function? */
     private Type returnType = Type.UNKNOWN;
@@ -352,7 +344,8 @@
         final Block body,
         final List<IdentNode> parameters,
         final int thisProperties,
-        final Class<?> rootClass) {
+        final Class<?> rootClass,
+        final Source source, Namespace namespace) {
         super(functionNode);
 
         this.endParserState    = endParserState;
@@ -367,11 +360,11 @@
         this.parameters       = parameters;
         this.thisProperties   = thisProperties;
         this.rootClass        = rootClass;
+        this.source           = source;
+        this.namespace        = namespace;
 
         // the fields below never change - they are final and assigned in constructor
-        this.source          = functionNode.source;
         this.ident           = functionNode.ident;
-        this.namespace       = functionNode.namespace;
         this.kind            = functionNode.kind;
         this.firstToken      = functionNode.firstToken;
     }
@@ -437,6 +430,39 @@
     }
 
     /**
+     * Sets the source and namespace for this function. It can only set a non-null source and namespace for a function
+     * that currently has both a null source and a null namespace. This is used to re-set the source and namespace for
+     * a deserialized function node.
+     * @param source the source for the function.
+     * @param namespace the namespace for the function
+     * @return a new function node with the set source and namespace
+     * @throws IllegalArgumentException if the specified source or namespace is null
+     * @throws IllegalStateException if the function already has either a source or namespace set.
+     */
+    public FunctionNode initializeDeserialized(final Source source, final Namespace namespace) {
+        if (source == null || namespace == null) {
+            throw new IllegalArgumentException();
+        } else if (this.source == source && this.namespace == namespace) {
+            return this;
+        } else if (this.source != null || this.namespace != null) {
+            throw new IllegalStateException();
+        }
+        return new FunctionNode(
+            this,
+            lastToken,
+            endParserState,
+            flags,
+            name,
+            returnType,
+            compileUnit,
+            compilationState,
+            body,
+            parameters,
+            thisProperties,
+            rootClass, source, namespace);
+    }
+
+    /**
      * Get the unique ID for this function within the script file.
      * @return the id
      */
@@ -537,6 +563,28 @@
         }
         final EnumSet<CompilationState> newState = EnumSet.copyOf(this.compilationState);
         newState.add(state);
+        return setCompilationState(lc, newState);
+    }
+
+    /**
+     * Copy a compilation state from an original function to this function. Used when creating synthetic
+     * function nodes by the splitter.
+     *
+     * @param lc lexical context
+     * @param original the original function node to copy compilation state from
+     * @return function node or a new one if state was changed
+     */
+    public FunctionNode copyCompilationState(final LexicalContext lc, final FunctionNode original) {
+        final EnumSet<CompilationState> origState = original.compilationState;
+        if (!AssertsEnabled.assertsEnabled() || this.compilationState.containsAll(origState)) {
+            return this;
+        }
+        final EnumSet<CompilationState> newState = EnumSet.copyOf(this.compilationState);
+        newState.addAll(origState);
+        return setCompilationState(lc, newState);
+    }
+
+    private FunctionNode setCompilationState(final LexicalContext lc, final EnumSet<CompilationState> compilationState) {
         return Node.replaceInLexicalContext(
                 lc,
                 this,
@@ -548,13 +596,14 @@
                         name,
                         returnType,
                         compileUnit,
-                        newState,
+                        compilationState,
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
+
     /**
      * Create a unique name in the namespace of this FunctionNode
      * @param base prefix for name
@@ -624,7 +673,7 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
     @Override
@@ -699,18 +748,11 @@
      * @return true if the function's generated Java method needs a {@code callee} parameter.
      */
     public boolean needsCallee() {
+        // NOTE: we only need isSplit() here to ensure that :scope can never drop below slot 2 for splitting array units.
         return needsParentScope() || usesSelfSymbol() || isSplit() || (needsArguments() && !isStrict()) || hasOptimisticApplyToCall();
     }
 
     /**
-     * Check if this function uses the return symbol
-     * @return true if uses the return symbol
-     */
-    public boolean usesReturnSymbol() {
-        return isProgram() || isSplit() || getFlag(USES_RETURN_SYMBOL);
-    }
-
-    /**
      * Return {@code true} if this function makes use of the {@code this} object.
      *
      * @return true if function uses {@code this} object
@@ -772,7 +814,7 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
     /**
@@ -840,7 +882,7 @@
      * @return true if the function needs parent scope.
      */
     public boolean needsParentScope() {
-        return getFlag(NEEDS_PARENT_SCOPE) || isProgram();
+        return getFlag(NEEDS_PARENT_SCOPE);
     }
 
     /**
@@ -868,7 +910,7 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
     /**
@@ -929,7 +971,7 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
     /**
@@ -964,7 +1006,10 @@
                         compilationState,
                         body,
                         parameters,
-                        thisProperties, rootClass));
+                        thisProperties,
+                        rootClass,
+                        source,
+                        namespace));
     }
 
     /**
@@ -1000,7 +1045,9 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass,
+                        source,
+                        namespace));
     }
 
     /**
@@ -1014,9 +1061,9 @@
     }
 
     /**
-     * Checks if this function is a sub-function generated by splitting a larger one
+     * Checks if this function is split into several smaller fragments.
      *
-     * @return true if this function is split from a larger one
+     * @return true if this function is split into several smaller fragments.
      */
     public boolean isSplit() {
         return getFlag(IS_SPLIT);
@@ -1066,7 +1113,7 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
     /**
@@ -1145,7 +1192,7 @@
                 body,
                 parameters,
                 thisProperties,
-                rootClass
+                rootClass, source, namespace
                 ));
    }
 
@@ -1193,7 +1240,7 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 
     /**
@@ -1249,6 +1296,6 @@
                         body,
                         parameters,
                         thisProperties,
-                        rootClass));
+                        rootClass, source, namespace));
     }
 }
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/GetSplitState.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/ir/GetSplitState.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.nashorn.internal.ir;
+
+import java.util.function.Function;
+import jdk.nashorn.internal.codegen.CompilerConstants;
+import jdk.nashorn.internal.codegen.types.Type;
+import jdk.nashorn.internal.ir.visitor.NodeVisitor;
+import jdk.nashorn.internal.runtime.Scope;
+
+/**
+ * Synthetic AST node that represents loading of the scope object and invocation of the {@link Scope#getSplitState()}
+ * method on it. It has no JavaScript source representation and only occurs in synthetic functions created by
+ * the split-into-functions transformation.
+ */
+public final class GetSplitState extends Expression {
+    private static final long serialVersionUID = 1L;
+
+    /** The sole instance of this AST node. */
+    public final static GetSplitState INSTANCE = new GetSplitState();
+
+    private GetSplitState() {
+        super(NO_TOKEN, NO_FINISH);
+    }
+
+    @Override
+    public Type getType(final Function<Symbol, Type> localVariableTypes) {
+        return Type.INT;
+    }
+
+    @Override
+    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
+        return visitor.enterGetSplitState(this) ? visitor.leaveGetSplitState(this) : this;
+    }
+
+    @Override
+    public void toString(final StringBuilder sb, final boolean printType) {
+        if (printType) {
+            sb.append("{I}");
+        }
+        sb.append(CompilerConstants.SCOPE.symbolName()).append('.').append(Scope.GET_SPLIT_STATE.name()).append("()");
+    }
+
+    private Object readResolve() {
+        return INSTANCE;
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/LexicalContext.java
--- a/src/jdk/nashorn/internal/ir/LexicalContext.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/LexicalContext.java	Mon Oct 20 12:06:36 2014 +0200
@@ -440,6 +440,14 @@
     }
 
     /**
+     * Is the topmost lexical context element body of a SplitNode?
+     * @return true if it's the body of a split node.
+     */
+    public boolean isSplitBody() {
+        return sp >= 2 && stack[sp - 1] instanceof Block && stack[sp - 2] instanceof SplitNode;
+    }
+
+    /**
      * Get the parent function for a function in the lexical context
      * @param functionNode function for which to get parent
      * @return parent function of functionNode or null if none (e.g. if functionNode is the program)
@@ -472,9 +480,6 @@
             final LexicalContextNode node = iter.next();
             if (node == until) {
                 break;
-            } else if (node instanceof SplitNode) {
-                // Don't bother popping scopes if we're going to do a return from a split method anyway.
-                return 0;
             }
             assert !(node instanceof FunctionNode); // Can't go outside current function
             if (node instanceof WithNode || node instanceof Block && ((Block)node).needsScope()) {
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/LiteralNode.java
--- a/src/jdk/nashorn/internal/ir/LiteralNode.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/LiteralNode.java	Mon Oct 20 12:06:36 2014 +0200
@@ -672,13 +672,13 @@
         private static final class ArrayLiteralInitializer {
 
             static ArrayLiteralNode initialize(final ArrayLiteralNode node) {
-                final Type elementType = computeElementType(node.value, node.elementType);
+                final Type elementType = computeElementType(node.value);
                 final int[] postsets = computePostsets(node.value);
                 final Object presets = computePresets(node.value, elementType, postsets);
                 return new ArrayLiteralNode(node, node.value, elementType, postsets, presets, node.units);
             }
 
-            private static Type computeElementType(final Expression[] value, final Type elementType) {
+            private static Type computeElementType(final Expression[] value) {
                 Type widestElementType = Type.INT;
 
                 for (final Expression elem : value) {
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/Node.java
--- a/src/jdk/nashorn/internal/ir/Node.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/Node.java	Mon Oct 20 12:06:36 2014 +0200
@@ -38,6 +38,15 @@
 public abstract class Node implements Cloneable, Serializable {
     private static final long serialVersionUID = 1L;
 
+    /** Constant used for synthetic AST nodes that have no line number. */
+    public static final int NO_LINE_NUMBER = -1;
+
+    /** Constant used for synthetic AST nodes that have no token. */
+    public static final long NO_TOKEN = 0L;
+
+    /** Constant used for synthetic AST nodes that have no finish. */
+    public static final int NO_FINISH = 0;
+
     /** Start of source range. */
     protected final int start;
 
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/SetSplitState.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/ir/SetSplitState.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.nashorn.internal.ir;
+
+import jdk.nashorn.internal.codegen.CompilerConstants;
+import jdk.nashorn.internal.ir.visitor.NodeVisitor;
+import jdk.nashorn.internal.runtime.Scope;
+
+/**
+ * Synthetic AST node that represents loading of the scope object and invocation of the {@link Scope#setSplitState(int)}
+ * method on it. It has no JavaScript source representation and only occurs in synthetic functions created by
+ * the split-into-functions transformation.
+ */
+public final class SetSplitState extends Statement {
+    private static final long serialVersionUID = 1L;
+
+    private final int state;
+
+    /**
+     * Creates a new split state setter
+     * @param state the state to set
+     * @param lineNumber the line number where it is inserted
+     */
+    public SetSplitState(final int state, final int lineNumber) {
+        super(lineNumber, NO_TOKEN, NO_FINISH);
+        this.state = state;
+    }
+
+    /**
+     * Returns the state this setter sets.
+     * @return the state this setter sets.
+     */
+    public int getState() {
+        return state;
+    }
+
+    @Override
+    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
+        return visitor.enterSetSplitState(this) ? visitor.leaveSetSplitState(this) : this;
+    }
+
+    @Override
+    public void toString(final StringBuilder sb, final boolean printType) {
+        sb.append(CompilerConstants.SCOPE.symbolName()).append('.').append(Scope.SET_SPLIT_STATE.name())
+        .append('(').append(state).append(");");
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/SplitNode.java
--- a/src/jdk/nashorn/internal/ir/SplitNode.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/SplitNode.java	Mon Oct 20 12:06:36 2014 +0200
@@ -25,13 +25,10 @@
 
 package jdk.nashorn.internal.ir;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.io.IOException;
+import java.io.NotSerializableException;
+import java.io.ObjectOutputStream;
 import jdk.nashorn.internal.codegen.CompileUnit;
-import jdk.nashorn.internal.codegen.Label;
 import jdk.nashorn.internal.ir.annotations.Immutable;
 import jdk.nashorn.internal.ir.visitor.NodeVisitor;
 
@@ -39,7 +36,7 @@
  * Node indicating code is split across classes.
  */
 @Immutable
-public class SplitNode extends LexicalContextStatement implements Labels, CompileUnitHolder {
+public class SplitNode extends LexicalContextStatement implements CompileUnitHolder {
     private static final long serialVersionUID = 1L;
 
     /** Split node method name. */
@@ -51,8 +48,6 @@
     /** Body of split code. */
     private final Block body;
 
-    private Map<Label, JoinPredecessor> jumps;
-
     /**
      * Constructor
      *
@@ -67,19 +62,18 @@
         this.compileUnit = compileUnit;
     }
 
-    private SplitNode(final SplitNode splitNode, final Block body, final CompileUnit compileUnit, final Map<Label, JoinPredecessor> jumps) {
+    private SplitNode(final SplitNode splitNode, final Block body, final CompileUnit compileUnit) {
         super(splitNode);
         this.name        = splitNode.name;
         this.body        = body;
         this.compileUnit = compileUnit;
-        this.jumps       = jumps;
     }
 
     /**
      * Get the body for this split node - i.e. the actual code it encloses
      * @return body for split node
      */
-    public Node getBody() {
+    public Block getBody() {
         return body;
     }
 
@@ -87,7 +81,7 @@
         if (this.body == body) {
             return this;
         }
-        return Node.replaceInLexicalContext(lc, this, new SplitNode(this, body, compileUnit, jumps));
+        return Node.replaceInLexicalContext(lc, this, new SplitNode(this, body, compileUnit));
     }
 
     @Override
@@ -133,33 +127,12 @@
         if (this.compileUnit == compileUnit) {
             return this;
         }
-        return Node.replaceInLexicalContext(lc, this, new SplitNode(this, body, compileUnit, jumps));
+        return Node.replaceInLexicalContext(lc, this, new SplitNode(this, body, compileUnit));
     }
 
-    /**
-     * Adds a jump that crosses this split node's boundary (it originates within the split node, and goes to a target
-     * outside of it).
-     * @param jumpOrigin the join predecessor that's the origin of the jump
-     * @param targetLabel the label that's the target of the jump.
-     */
-    public void addJump(final JoinPredecessor jumpOrigin, final Label targetLabel) {
-        if (jumps == null) {
-            jumps = new HashMap<>();
-        }
-        jumps.put(targetLabel, jumpOrigin);
-    }
-
-    /**
-     * Returns the jump origin within this split node for a target.
-     * @param targetLabel the target for which a jump origin is sought.
-     * @return the jump origin, or null.
-     */
-    public JoinPredecessor getJumpOrigin(final Label targetLabel) {
-        return jumps == null ? null : jumps.get(targetLabel);
-    }
-
-    @Override
-    public List<Label> getLabels() {
-        return Collections.unmodifiableList(new ArrayList<>(jumps.keySet()));
+    private void writeObject(final ObjectOutputStream out) throws IOException {
+        // We are only serializing the AST after we run SplitIntoFunctions; no SplitNodes can remain for the
+        // serialization.
+        throw new NotSerializableException(getClass().getName());
     }
 }
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/SplitReturn.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/ir/SplitReturn.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.nashorn.internal.ir;
+
+import jdk.nashorn.internal.ir.visitor.NodeVisitor;
+
+/**
+ * Synthetic AST node that represents return from a split fragment of a split function for control flow reasons (break
+ * or continue into a target outside the current fragment). It has no JavaScript source representation and only occurs
+ * in synthetic functions created by the split-into-functions transformation. It is different from a return node in
+ * that the return value is irrelevant, and doesn't affect the function's return type calculation.
+ */
+public final class SplitReturn extends Statement {
+    private static final long serialVersionUID = 1L;
+
+    /** The sole instance of this AST node. */
+    public static final SplitReturn INSTANCE = new SplitReturn();
+
+    private SplitReturn() {
+        super(NO_LINE_NUMBER, NO_TOKEN, NO_FINISH);
+    }
+
+    @Override
+    public boolean isTerminal() {
+        return true;
+    }
+
+    @Override
+    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
+        return visitor.enterSplitReturn(this) ? visitor.leaveSplitReturn(this) : this;
+    }
+
+    @Override
+    public void toString(StringBuilder sb, boolean printType) {
+        sb.append(":splitreturn;");
+    }
+
+    private Object readResolve() {
+        return INSTANCE;
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/Symbol.java
--- a/src/jdk/nashorn/internal/ir/Symbol.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/Symbol.java	Mon Oct 20 12:06:36 2014 +0200
@@ -97,7 +97,7 @@
     private int firstSlot = -1;
 
     /** Field number in scope or property; array index in varargs when not using arguments object. */
-    private int fieldIndex;
+    private int fieldIndex = -1;
 
     /** Number of times this symbol is used in code */
     private int useCount;
@@ -135,28 +135,15 @@
      *
      * @param name  name of symbol
      * @param flags symbol flags
-     * @param slot  bytecode slot for this symbol
      */
-    protected Symbol(final String name, final int flags, final int slot) {
+    public Symbol(final String name, final int flags) {
         this.name       = name;
         this.flags      = flags;
-        this.firstSlot  = slot;
-        this.fieldIndex = -1;
         if(shouldTrace()) {
             trace("CREATE SYMBOL " + name);
         }
     }
 
-    /**
-     * Constructor
-     *
-     * @param name  name of symbol
-     * @param flags symbol flags
-     */
-    public Symbol(final String name, final int flags) {
-        this(name, flags, -1);
-    }
-
     private static String align(final String string, final int max) {
         final StringBuilder sb = new StringBuilder();
         sb.append(string.substring(0, Math.min(string.length(), max)));
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/ir/visitor/NodeVisitor.java
--- a/src/jdk/nashorn/internal/ir/visitor/NodeVisitor.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/ir/visitor/NodeVisitor.java	Mon Oct 20 12:06:36 2014 +0200
@@ -38,6 +38,7 @@
 import jdk.nashorn.internal.ir.ExpressionStatement;
 import jdk.nashorn.internal.ir.ForNode;
 import jdk.nashorn.internal.ir.FunctionNode;
+import jdk.nashorn.internal.ir.GetSplitState;
 import jdk.nashorn.internal.ir.IdentNode;
 import jdk.nashorn.internal.ir.IfNode;
 import jdk.nashorn.internal.ir.IndexNode;
@@ -50,7 +51,9 @@
 import jdk.nashorn.internal.ir.PropertyNode;
 import jdk.nashorn.internal.ir.ReturnNode;
 import jdk.nashorn.internal.ir.RuntimeNode;
+import jdk.nashorn.internal.ir.SetSplitState;
 import jdk.nashorn.internal.ir.SplitNode;
+import jdk.nashorn.internal.ir.SplitReturn;
 import jdk.nashorn.internal.ir.SwitchNode;
 import jdk.nashorn.internal.ir.TernaryNode;
 import jdk.nashorn.internal.ir.ThrowNode;
@@ -390,6 +393,26 @@
     }
 
     /**
+     * Callback for entering a {@link GetSplitState}.
+     *
+     * @param  getSplitState the get split state expression
+     * @return true if traversal should continue and node children be traversed, false otherwise
+     */
+    public boolean enterGetSplitState(final GetSplitState getSplitState) {
+        return enterDefault(getSplitState);
+    }
+
+    /**
+     * Callback for leaving a {@link GetSplitState}.
+     *
+     * @param  getSplitState the get split state expression
+     * @return processed node, which will replace the original one, or the original node
+     */
+    public Node leaveGetSplitState(final GetSplitState getSplitState) {
+        return leaveDefault(getSplitState);
+    }
+
+    /**
      * Callback for entering an IdentNode
      *
      * @param  identNode the node
@@ -570,6 +593,26 @@
     }
 
     /**
+     * Callback for entering a {@link SetSplitState}.
+     *
+     * @param  setSplitState the set split state statement
+     * @return true if traversal should continue and node children be traversed, false otherwise
+     */
+    public boolean enterSetSplitState(final SetSplitState setSplitState) {
+        return enterDefault(setSplitState);
+    }
+
+    /**
+     * Callback for leaving a {@link SetSplitState}.
+     *
+     * @param  setSplitState the set split state expression
+     * @return processed node, which will replace the original one, or the original node
+     */
+    public Node leaveSetSplitState(final SetSplitState setSplitState) {
+        return leaveDefault(setSplitState);
+    }
+
+    /**
      * Callback for entering a SplitNode
      *
      * @param  splitNode the node
@@ -590,6 +633,26 @@
     }
 
     /**
+     * Callback for entering a SplitReturn
+     *
+     * @param  splitReturn the node
+     * @return true if traversal should continue and node children be traversed, false otherwise
+     */
+    public boolean enterSplitReturn(final SplitReturn splitReturn) {
+        return enterDefault(splitReturn);
+    }
+
+    /**
+     * Callback for leaving a SplitReturn
+     *
+     * @param  splitReturn the node
+     * @return processed node, which will replace the original one, or the original node
+     */
+    public Node leaveSplitReturn(final SplitReturn splitReturn) {
+        return leaveDefault(splitReturn);
+    }
+
+    /**
      * Callback for entering a SwitchNode
      *
      * @param  switchNode the node
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/runtime/AstDeserializer.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/runtime/AstDeserializer.java	Mon Oct 20 12:06:36 2014 +0200
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.nashorn.internal.runtime;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.util.zip.InflaterInputStream;
+import jdk.nashorn.internal.ir.FunctionNode;
+
+/**
+ * This static utility class performs deserialization of FunctionNode ASTs from a byte array.
+ * The format is a standard Java serialization stream, deflated.
+ */
+final class AstDeserializer {
+    static FunctionNode deserialize(final byte[] serializedAst) {
+        try {
+            return (FunctionNode)new ObjectInputStream(new InflaterInputStream(new ByteArrayInputStream(
+                    serializedAst))).readObject();
+        } catch (final ClassNotFoundException | IOException e) {
+            // This is internal, can't happen
+            throw new AssertionError("Unexpected exception deserializing function", e);
+        }
+    }
+}
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/runtime/CompiledFunction.java
--- a/src/jdk/nashorn/internal/runtime/CompiledFunction.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/runtime/CompiledFunction.java	Mon Oct 20 12:06:36 2014 +0200
@@ -27,6 +27,7 @@
 import static jdk.nashorn.internal.lookup.Lookup.MH;
 import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.INVALID_PROGRAM_POINT;
 import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.isValid;
+
 import java.lang.invoke.CallSite;
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
@@ -786,6 +787,7 @@
         // isn't available, we'll use the old one bound into the call site.
         final OptimismInfo effectiveOptInfo = currentOptInfo != null ? currentOptInfo : oldOptInfo;
         FunctionNode fn = effectiveOptInfo.reparse();
+        final boolean serialized = effectiveOptInfo.isSerialized();
         final Compiler compiler = effectiveOptInfo.getCompiler(fn, callSiteType, re); //set to non rest-of
 
         if (!shouldRecompile) {
@@ -793,17 +795,17 @@
             // recompiled a deoptimized version for an inner invocation.
             // We still need to do the rest of from the beginning
             logRecompile("Rest-of compilation [STANDALONE] ", fn, callSiteType, effectiveOptInfo.invalidatedProgramPoints);
-            return restOfHandle(effectiveOptInfo, compiler.compile(fn, CompilationPhases.COMPILE_ALL_RESTOF), currentOptInfo != null);
+            return restOfHandle(effectiveOptInfo, compiler.compile(fn, serialized ? CompilationPhases.COMPILE_SERIALIZED_RESTOF : CompilationPhases.COMPILE_ALL_RESTOF), currentOptInfo != null);
         }
 
         logRecompile("Deoptimizing recompilation (up to bytecode) ", fn, callSiteType, effectiveOptInfo.invalidatedProgramPoints);
-        fn = compiler.compile(fn, CompilationPhases.COMPILE_UPTO_BYTECODE);
+        fn = compiler.compile(fn, serialized ? CompilationPhases.RECOMPILE_SERIALIZED_UPTO_BYTECODE : CompilationPhases.COMPILE_UPTO_BYTECODE);
         log.info("Reusable IR generated");
 
         // compile the rest of the function, and install it
         log.info("Generating and installing bytecode from reusable IR...");
         logRecompile("Rest-of compilation [CODE PIPELINE REUSE] ", fn, callSiteType, effectiveOptInfo.invalidatedProgramPoints);
-        final FunctionNode normalFn = compiler.compile(fn, CompilationPhases.COMPILE_FROM_BYTECODE);
+        final FunctionNode normalFn = compiler.compile(fn, CompilationPhases.GENERATE_BYTECODE_AND_INSTALL);
 
         if (effectiveOptInfo.data.usePersistentCodeCache()) {
             final RecompilableScriptFunctionData data = effectiveOptInfo.data;
@@ -829,7 +831,7 @@
         constructor = null; // Will be regenerated when needed
 
         log.info("Done: ", invoker);
-        final MethodHandle restOf = restOfHandle(effectiveOptInfo, compiler.compile(fn, CompilationPhases.COMPILE_FROM_BYTECODE_RESTOF), canBeDeoptimized);
+        final MethodHandle restOf = restOfHandle(effectiveOptInfo, compiler.compile(fn, CompilationPhases.GENERATE_BYTECODE_AND_INSTALL_RESTOF), canBeDeoptimized);
 
         // Note that we only adjust the switch point after we set the invoker/constructor. This is important.
         if (canBeDeoptimized) {
@@ -921,6 +923,10 @@
         FunctionNode reparse() {
             return data.reparse();
         }
+
+        boolean isSerialized() {
+            return data.isSerialized();
+        }
     }
 
     @SuppressWarnings("unused")
diff -r 8c51767d534d -r 03c06c337d9d src/jdk/nashorn/internal/runtime/RecompilableScriptFunctionData.java
--- a/src/jdk/nashorn/internal/runtime/RecompilableScriptFunctionData.java	Fri Oct 17 14:24:26 2014 +0200
+++ b/src/jdk/nashorn/internal/runtime/RecompilableScriptFunctionData.java	Mon Oct 20 12:06:36 2014 +0200
@@ -43,6 +43,7 @@
 import jdk.nashorn.internal.codegen.Compiler.CompilationPhases;
 import jdk.nashorn.internal.codegen.CompilerConstants;
 import jdk.nashorn.internal.codegen.FunctionSignature;
+import jdk.nashorn.internal.codegen.Namespace;
 import jdk.nashorn.internal.codegen.ObjectClassGenerator.AllocatorDescriptor;
 import jdk.nashorn.internal.codegen.OptimisticTypesPersistence;
 import jdk.nashorn.internal.codegen.TypeMap;
@@ -79,6 +80,9 @@
     /** Source from which FunctionNode was parsed. */
     private transient Source source;
 
+    /** Serialized, compressed form of the AST. Used by split functions as they can't be reparsed from source. */
+    private final byte[] serializedAst;
+
     /** Token of this function within the source. */
     private final long token;
 
@@ -127,6 +131,7 @@
      * @param nestedFunctions     nested function map
      * @param externalScopeDepths external scope depths
      * @param internalSymbols     internal symbols to method, defined in its scope
+     * @param serializedAst       a serialized AST representation. Normally only used for split functions.
      */
     public RecompilableScriptFunctionData(
         final FunctionNode functionNode,
@@ -134,7 +139,8 @@
         final AllocatorDescriptor allocationDescriptor,
         final Map<Integer, RecompilableScriptFunctionData> nestedFunctions,
         final Map<String, Integer> externalScopeDepths,
-        final Set<String> internalSymbols) {
+        final Set<String> internalSymbols,
+        final byte[] serializedAst) {
 
         super(functionName(functionNode),
               Math.min(functionNode.getParameters().size(), MAX_ARITY),
@@ -158,6 +164,7 @@
             nfn.setParent(this);
         }
 
+        this.serializedAst = serializedAst;
         createLogger();
     }
 
@@ -212,10 +219,7 @@
      */
     public int getExternalSymbolDepth(final String symbolName) {
         final Integer depth = externalScopeDepths.get(symbolName);
-        if (depth == null) {
-            return -1;
-        }
-        return depth;
+        return depth == null ? -1 : depth;
     }
 
     /**
@@ -354,8 +358,15 @@
         return allocationStrategy.allocate(map);
     }
 
+    boolean isSerialized() {
+        return serializedAst != null;
+    }
+
     FunctionNode reparse() {
-        // NOTE: If we aren't recompiling the top-level program, we decrease functionNodeId 'cause we'll have a synthetic program node
+        if (isSerialized()) {
+            return deserialize();
+        }
+
         final int descPosition = Token.descPosition(token);
         final Context context = Context.getContextTrusted();
         final Parser parser = new Parser(
@@ -363,8 +374,10 @@
             source,
             new Context.ThrowErrorManager(),
             isStrict(),
+            // source starts at line 0, so even though lineNumber is the correct declaration line, back off
+            // one to make it exclusive
             lineNumber - 1,
-            context.getLogger(Parser.class)); // source starts at line 0, so even though lineNumber is the correct declaration line, back off one to make it exclusive
+            context.getLogger(Parser.class));
 
         if (getFunctionFlag(FunctionNode.IS_ANONYMOUS)) {
             parser.setFunctionName(functionName);
@@ -378,6 +391,17 @@
         return (isProgram() ? program : extractFunctionFromScript(program)).setName(null, functionName);
     }
 
+    private FunctionNode deserialize() {
+        final ScriptEnvironment env = installer.getOwner();
+        final Timing timing = env._timing;
+        final long t1 = System.nanoTime();
+        try {
+            return AstDeserializer.deserialize(serializedAst).initializeDeserialized(source, new Namespace(env.getNamespace()));
+        } finally {
+            timing.accumulateTime("'Deserialize'", System.nanoTime() - t1);
+        }
+    }
+
     private boolean getFunctionFlag(final int flag) {
         return (functionFlags & flag) != 0;
     }
@@ -486,7 +510,8 @@
 
         final FunctionNode fn = reparse();
         final Compiler compiler = getCompiler(fn, actualCallSiteType, runtimeScope);
-        final FunctionNode compiledFn = compiler.compile(fn, CompilationPhases.COMPILE_ALL);
+        final FunctionNode compiledFn = compiler.compile(fn,
+                isSerialized() ? CompilationPhases.COMPILE_ALL_SERIALIZED : CompilationPhases.COMPILE_ALL);
 
         if (persist && !compiledFn.getFlag(FunctionNode.HAS_APPLY_TO_CALL_SPECIALIZATION)) {
             compiler.persistClassInfo(cacheKey, compiledFn);
@@ -606,7 +631,7 @@
 
     MethodHandle lookupCodeMethod(final Class<?> codeClass, final MethodType targetType) {
         if (log.isEnabled()) {
-            log.info("Looking up ", DebugLogger.quote(name), " type=", targetType);
+            log.info("Looking up ", DebugLogger.quote(functionName), " type=", targetType);
         }
         return MH.findStatic(LOOKUP, codeClass, functionName, targetType);
     }
@@ -817,6 +842,26 @@
         return true;
     }
 
+    /**
+     * Restores the {@link #getFunctionFlags()} flags to a function node. During on-demand compilation, we might need
+     * to restore flags to a function node that was otherwise not subjected to a full compile pipeline (e.g. its parse
+     * was skipped, or it's a nested function of a deserialized function.
+     * @param lc current lexical context
+     * @param fn the function node to restore flags onto
+     * @return the transformed function node
+     */
+    public FunctionNode restoreFlags(final LexicalContext lc, final FunctionNode fn) {
+        assert fn.getId() == functionNodeId;
+        FunctionNode newFn = fn.setFlags(lc, functionFlags);
+        // This compensates for missing markEval() in case the function contains an inner function
+        // that contains eval(), that now we didn't discover since we skipped the inner function.
+        if (newFn.hasNestedEval()) {
+            assert newFn.hasScopeBlock();
+            newFn = newFn.setBody(lc, newFn.getBody().setNeedsScope(null));
+        }
+        return newFn;
+    }
+
     private void readObject(final java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
         createLogger();