src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/RecompilableScriptFunctionData.java
changeset 47216 71c04702a3d5
parent 43117 2027548da50f
child 58379 8511c662083b
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/RecompilableScriptFunctionData.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1068 @@
+/*
+ * 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 static jdk.nashorn.internal.lookup.Lookup.MH;
+
+import java.io.IOException;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.ref.Reference;
+import java.lang.ref.SoftReference;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.IdentityHashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import jdk.nashorn.internal.codegen.Compiler;
+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.OptimisticTypesPersistence;
+import jdk.nashorn.internal.codegen.TypeMap;
+import jdk.nashorn.internal.codegen.types.Type;
+import jdk.nashorn.internal.ir.Block;
+import jdk.nashorn.internal.ir.ForNode;
+import jdk.nashorn.internal.ir.FunctionNode;
+import jdk.nashorn.internal.ir.IdentNode;
+import jdk.nashorn.internal.ir.LexicalContext;
+import jdk.nashorn.internal.ir.Node;
+import jdk.nashorn.internal.ir.SwitchNode;
+import jdk.nashorn.internal.ir.Symbol;
+import jdk.nashorn.internal.ir.TryNode;
+import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor;
+import jdk.nashorn.internal.objects.Global;
+import jdk.nashorn.internal.parser.Parser;
+import jdk.nashorn.internal.parser.Token;
+import jdk.nashorn.internal.parser.TokenType;
+import jdk.nashorn.internal.runtime.linker.NameCodec;
+import jdk.nashorn.internal.runtime.logging.DebugLogger;
+import jdk.nashorn.internal.runtime.logging.Loggable;
+import jdk.nashorn.internal.runtime.logging.Logger;
+import jdk.nashorn.internal.runtime.options.Options;
+/**
+ * This is a subclass that represents a script function that may be regenerated,
+ * for example with specialization based on call site types, or lazily generated.
+ * The common denominator is that it can get new invokers during its lifespan,
+ * unlike {@code FinalScriptFunctionData}
+ */
+@Logger(name="recompile")
+public final class RecompilableScriptFunctionData extends ScriptFunctionData implements Loggable {
+    /** Prefix used for all recompiled script classes */
+    public static final String RECOMPILATION_PREFIX = "Recompilation$";
+
+    private static final ExecutorService astSerializerExecutorService = createAstSerializerExecutorService();
+
+    /** Unique function node id for this function node */
+    private final int functionNodeId;
+
+    private final String functionName;
+
+    /** The line number where this function begins. */
+    private final int lineNumber;
+
+    /** Source from which FunctionNode was parsed. */
+    private transient Source source;
+
+    /**
+     * Cached form of the AST. Either a {@code SerializedAst} object used by split functions as they can't be
+     * reparsed from source, or a soft reference to a {@code FunctionNode} for other functions (it is safe
+     * to be cleared as they can be reparsed).
+     */
+    private volatile transient Object cachedAst;
+
+    /** Token of this function within the source. */
+    private final long token;
+
+    /**
+     * Represents the allocation strategy (property map, script object class, and method handle) for when
+     * this function is used as a constructor. Note that majority of functions (those not setting any this.*
+     * properties) will share a single canonical "default strategy" instance.
+     */
+    private final AllocationStrategy allocationStrategy;
+
+    /**
+     * Opaque object representing parser state at the end of the function. Used when reparsing outer function
+     * to help with skipping parsing inner functions.
+     */
+    private final Object endParserState;
+
+    /** Code installer used for all further recompilation/specialization of this ScriptFunction */
+    private transient CodeInstaller installer;
+
+    private final Map<Integer, RecompilableScriptFunctionData> nestedFunctions;
+
+    /** Id to parent function if one exists */
+    private RecompilableScriptFunctionData parent;
+
+    /** Copy of the {@link FunctionNode} flags. */
+    private final int functionFlags;
+
+    private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
+
+    private transient DebugLogger log;
+
+    private final Map<String, Integer> externalScopeDepths;
+
+    private final Set<String> internalSymbols;
+
+    private static final int GET_SET_PREFIX_LENGTH = "*et ".length();
+
+    private static final long serialVersionUID = 4914839316174633726L;
+
+    /**
+     * Constructor - public as scripts use it
+     *
+     * @param functionNode        functionNode that represents this function code
+     * @param installer           installer for code regeneration versions of this function
+     * @param allocationStrategy  strategy for the allocation behavior when this function is used as a constructor
+     * @param nestedFunctions     nested function map
+     * @param externalScopeDepths external scope depths
+     * @param internalSymbols     internal symbols to method, defined in its scope
+     */
+    public RecompilableScriptFunctionData(
+        final FunctionNode functionNode,
+        final CodeInstaller installer,
+        final AllocationStrategy allocationStrategy,
+        final Map<Integer, RecompilableScriptFunctionData> nestedFunctions,
+        final Map<String, Integer> externalScopeDepths,
+        final Set<String> internalSymbols) {
+
+        super(functionName(functionNode),
+              Math.min(functionNode.getParameters().size(), MAX_ARITY),
+              getDataFlags(functionNode));
+
+        this.functionName        = functionNode.getName();
+        this.lineNumber          = functionNode.getLineNumber();
+        this.functionFlags       = functionNode.getFlags() | (functionNode.needsCallee() ? FunctionNode.NEEDS_CALLEE : 0);
+        this.functionNodeId      = functionNode.getId();
+        this.source              = functionNode.getSource();
+        this.endParserState      = functionNode.getEndParserState();
+        this.token               = tokenFor(functionNode);
+        this.installer           = installer;
+        this.allocationStrategy  = allocationStrategy;
+        this.nestedFunctions     = smallMap(nestedFunctions);
+        this.externalScopeDepths = smallMap(externalScopeDepths);
+        this.internalSymbols     = smallSet(new HashSet<>(internalSymbols));
+
+        for (final RecompilableScriptFunctionData nfn : nestedFunctions.values()) {
+            assert nfn.getParent() == null;
+            nfn.setParent(this);
+        }
+
+        createLogger();
+    }
+
+    private static <K, V> Map<K, V> smallMap(final Map<K, V> map) {
+        if (map == null || map.isEmpty()) {
+            return Collections.emptyMap();
+        } else if (map.size() == 1) {
+            final Map.Entry<K, V> entry = map.entrySet().iterator().next();
+            return Collections.singletonMap(entry.getKey(), entry.getValue());
+        } else {
+            return map;
+        }
+    }
+
+    private static <T> Set<T> smallSet(final Set<T> set) {
+        if (set == null || set.isEmpty()) {
+            return Collections.emptySet();
+        } else if (set.size() == 1) {
+            return Collections.singleton(set.iterator().next());
+        } else {
+            return set;
+        }
+    }
+
+    @Override
+    public DebugLogger getLogger() {
+        return log;
+    }
+
+    @Override
+    public DebugLogger initLogger(final Context ctxt) {
+        return ctxt.getLogger(this.getClass());
+    }
+
+    /**
+     * Check if a symbol is internally defined in a function. For example
+     * if "undefined" is internally defined in the outermost program function,
+     * it has not been reassigned or overridden and can be optimized
+     *
+     * @param symbolName symbol name
+     * @return true if symbol is internal to this ScriptFunction
+     */
+
+    public boolean hasInternalSymbol(final String symbolName) {
+        return internalSymbols.contains(symbolName);
+    }
+
+    /**
+     * Return the external symbol table
+     * @param symbolName symbol name
+     * @return the external symbol table with proto depths
+     */
+    public int getExternalSymbolDepth(final String symbolName) {
+        final Integer depth = externalScopeDepths.get(symbolName);
+        return depth == null ? -1 : depth;
+    }
+
+    /**
+     * Returns the names of all external symbols this function uses.
+     * @return the names of all external symbols this function uses.
+     */
+    public Set<String> getExternalSymbolNames() {
+        return Collections.unmodifiableSet(externalScopeDepths.keySet());
+    }
+
+    /**
+     * Returns the opaque object representing the parser state at the end of this function's body, used to
+     * skip parsing this function when reparsing its containing outer function.
+     * @return the object representing the end parser state
+     */
+    public Object getEndParserState() {
+        return endParserState;
+    }
+
+    /**
+     * Get the parent of this RecompilableScriptFunctionData. If we are
+     * a nested function, we have a parent. Note that "null" return value
+     * can also mean that we have a parent but it is unknown, so this can
+     * only be used for conservative assumptions.
+     * @return parent data, or null if non exists and also null IF UNKNOWN.
+     */
+    public RecompilableScriptFunctionData getParent() {
+        return parent;
+    }
+
+    void setParent(final RecompilableScriptFunctionData parent) {
+        this.parent = parent;
+    }
+
+    @Override
+    String toSource() {
+        if (source != null && token != 0) {
+            return source.getString(Token.descPosition(token), Token.descLength(token));
+        }
+
+        return "function " + (name == null ? "" : name) + "() { [native code] }";
+    }
+
+    /**
+     * Initialize transient fields on deserialized instances
+     *
+     * @param src source
+     * @param inst code installer
+     */
+    public void initTransients(final Source src, final CodeInstaller inst) {
+        if (this.source == null && this.installer == null) {
+            this.source    = src;
+            this.installer = inst;
+            for (final RecompilableScriptFunctionData nested : nestedFunctions.values()) {
+                nested.initTransients(src, inst);
+            }
+        } else if (this.source != src || !this.installer.isCompatibleWith(inst)) {
+            // Existing values must be same as those passed as parameters
+            throw new IllegalArgumentException();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return super.toString() + '@' + functionNodeId;
+    }
+
+    @Override
+    public String toStringVerbose() {
+        final StringBuilder sb = new StringBuilder();
+
+        sb.append("fnId=").append(functionNodeId).append(' ');
+
+        if (source != null) {
+            sb.append(source.getName())
+                .append(':')
+                .append(lineNumber)
+                .append(' ');
+        }
+
+        return sb.toString() + super.toString();
+    }
+
+    @Override
+    public String getFunctionName() {
+        return functionName;
+    }
+
+    @Override
+    public boolean inDynamicContext() {
+        return getFunctionFlag(FunctionNode.IN_DYNAMIC_CONTEXT);
+    }
+
+    private static String functionName(final FunctionNode fn) {
+        if (fn.isAnonymous()) {
+            return "";
+        }
+        final FunctionNode.Kind kind = fn.getKind();
+        if (kind == FunctionNode.Kind.GETTER || kind == FunctionNode.Kind.SETTER) {
+            final String name = NameCodec.decode(fn.getIdent().getName());
+            return name.substring(GET_SET_PREFIX_LENGTH);
+        }
+        return fn.getIdent().getName();
+    }
+
+    private static long tokenFor(final FunctionNode fn) {
+        final int  position  = Token.descPosition(fn.getFirstToken());
+        final long lastToken = Token.withDelimiter(fn.getLastToken());
+        // EOL uses length field to store the line number
+        final int  length    = Token.descPosition(lastToken) - position + (Token.descType(lastToken) == TokenType.EOL ? 0 : Token.descLength(lastToken));
+
+        return Token.toDesc(TokenType.FUNCTION, position, length);
+    }
+
+    private static int getDataFlags(final FunctionNode functionNode) {
+        int flags = IS_CONSTRUCTOR;
+        if (functionNode.isStrict()) {
+            flags |= IS_STRICT;
+        }
+        if (functionNode.needsCallee()) {
+            flags |= NEEDS_CALLEE;
+        }
+        if (functionNode.usesThis() || functionNode.hasEval()) {
+            flags |= USES_THIS;
+        }
+        if (functionNode.isVarArg()) {
+            flags |= IS_VARIABLE_ARITY;
+        }
+        if (functionNode.getKind() == FunctionNode.Kind.GETTER || functionNode.getKind() == FunctionNode.Kind.SETTER) {
+            flags |= IS_PROPERTY_ACCESSOR;
+        }
+        if (functionNode.isMethod() || functionNode.isClassConstructor()) {
+            flags |= IS_ES6_METHOD;
+        }
+        return flags;
+    }
+
+    @Override
+    PropertyMap getAllocatorMap(final ScriptObject prototype) {
+        return allocationStrategy.getAllocatorMap(prototype);
+    }
+
+    @Override
+    ScriptObject allocate(final PropertyMap map) {
+        return allocationStrategy.allocate(map);
+    }
+
+    FunctionNode reparse() {
+        final FunctionNode cachedFunction = getCachedAst();
+        if (cachedFunction != null) {
+            assert cachedFunction.isCached();
+            return cachedFunction;
+        }
+
+        final int descPosition = Token.descPosition(token);
+        final Context context = Context.getContextTrusted();
+        final Parser parser = new Parser(
+            context.getEnv(),
+            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));
+
+        if (getFunctionFlag(FunctionNode.IS_ANONYMOUS)) {
+            parser.setFunctionName(functionName);
+        }
+        parser.setReparsedFunction(this);
+
+        final FunctionNode program = parser.parse(CompilerConstants.PROGRAM.symbolName(), descPosition,
+                Token.descLength(token), flags);
+        // Parser generates a program AST even if we're recompiling a single function, so when we are only
+        // recompiling a single function, extract it from the program.
+        return (isProgram() ? program : extractFunctionFromScript(program)).setName(null, functionName);
+    }
+
+    private FunctionNode getCachedAst() {
+        final Object lCachedAst = cachedAst;
+        // Are we softly caching the AST?
+        if (lCachedAst instanceof Reference<?>) {
+            final FunctionNode fn = (FunctionNode)((Reference<?>)lCachedAst).get();
+            if (fn != null) {
+                // Yes we are - this is fast
+                return cloneSymbols(fn);
+            }
+        // Are we strongly caching a serialized AST (for split functions only)?
+        } else if (lCachedAst instanceof SerializedAst) {
+            final SerializedAst serializedAst = (SerializedAst)lCachedAst;
+            // Even so, are we also softly caching the AST?
+            final FunctionNode cachedFn = serializedAst.cachedAst == null ? null : serializedAst.cachedAst.get();
+            if (cachedFn != null) {
+                // Yes we are - this is fast
+                return cloneSymbols(cachedFn);
+            }
+            final FunctionNode deserializedFn = deserialize(serializedAst.serializedAst);
+            // Softly cache after deserialization, maybe next time we won't need to deserialize
+            serializedAst.cachedAst = new SoftReference<>(deserializedFn);
+            return deserializedFn;
+        }
+        // No cached representation; return null for reparsing
+        return null;
+    }
+
+    /**
+     * Sets the AST to cache in this function
+     * @param astToCache the new AST to cache
+     */
+    public void setCachedAst(final FunctionNode astToCache) {
+        assert astToCache.getId() == functionNodeId; // same function
+        assert !(cachedAst instanceof SerializedAst); // Can't overwrite serialized AST
+
+        final boolean isSplit = astToCache.isSplit();
+        // If we're caching a split function, we're doing it in the eager pass, hence there can be no other
+        // cached representation already. In other words, isSplit implies cachedAst == null.
+        assert !isSplit || cachedAst == null; //
+
+        final FunctionNode symbolClonedAst = cloneSymbols(astToCache);
+        final Reference<FunctionNode> ref = new SoftReference<>(symbolClonedAst);
+        cachedAst = ref;
+
+        // Asynchronously serialize split functions.
+        if (isSplit) {
+            astSerializerExecutorService.execute(() -> {
+                cachedAst = new SerializedAst(symbolClonedAst, ref);
+            });
+        }
+    }
+
+    /**
+     * Creates the AST serializer executor service used for in-memory serialization of split functions' ASTs.
+     * It is created with an unbounded queue (so it can queue any number of pending tasks). Its core and max
+     * threads is the same, but they are all allowed to time out so when there's no work, they can all go
+     * away. The threads will be daemons, and they will time out if idle for a minute. Their priority is also
+     * slightly lower than normal priority as we'd prefer the CPU to keep running the program; serializing
+     * split function is a memory conservation measure (it allows us to release the AST), it can wait a bit.
+     * @return an executor service with above described characteristics.
+     */
+    private static ExecutorService createAstSerializerExecutorService() {
+        final int threads = Math.max(1, Options.getIntProperty("nashorn.serialize.threads", Runtime.getRuntime().availableProcessors() / 2));
+        final ThreadPoolExecutor service = new ThreadPoolExecutor(threads, threads, 1, TimeUnit.MINUTES, new LinkedBlockingDeque<>(),
+            (r) -> {
+                final Thread t = new Thread(r, "Nashorn AST Serializer");
+                t.setDaemon(true);
+                t.setPriority(Thread.NORM_PRIORITY - 1);
+                return t;
+            });
+        service.allowCoreThreadTimeOut(true);
+        return service;
+    }
+
+    /**
+     * A tuple of a serialized AST and a soft reference to a deserialized AST. This is used to cache split
+     * functions. Since split functions are altered from their source form, they can't be reparsed from
+     * source. While we could just use the {@code byte[]} representation in {@link RecompilableScriptFunctionData#cachedAst}
+     * we're using this tuple instead to also keep a deserialized AST around in memory to cut down on
+     * deserialization costs.
+     */
+    private static class SerializedAst implements Serializable {
+        private final byte[] serializedAst;
+        private volatile transient Reference<FunctionNode> cachedAst;
+
+        private static final long serialVersionUID = 1L;
+
+        SerializedAst(final FunctionNode fn, final Reference<FunctionNode> cachedAst) {
+            this.serializedAst = AstSerializer.serialize(fn);
+            this.cachedAst = cachedAst;
+        }
+    }
+
+    private FunctionNode deserialize(final byte[] serializedAst) {
+        final ScriptEnvironment env = installer.getContext().getEnv();
+        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 FunctionNode cloneSymbols(final FunctionNode fn) {
+        final IdentityHashMap<Symbol, Symbol> symbolReplacements = new IdentityHashMap<>();
+        final boolean cached = fn.isCached();
+        // blockDefinedSymbols is used to re-mark symbols defined outside the function as global. We only
+        // need to do this when we cache an eagerly parsed function (which currently means a split one, as we
+        // don't cache non-split functions from the eager pass); those already cached, or those not split
+        // don't need this step.
+        final Set<Symbol> blockDefinedSymbols = fn.isSplit() && !cached ? Collections.newSetFromMap(new IdentityHashMap<>()) : null;
+        FunctionNode newFn = (FunctionNode)fn.accept(new SimpleNodeVisitor() {
+            private Symbol getReplacement(final Symbol original) {
+                if (original == null) {
+                    return null;
+                }
+                final Symbol existingReplacement = symbolReplacements.get(original);
+                if (existingReplacement != null) {
+                    return existingReplacement;
+                }
+                final Symbol newReplacement = original.clone();
+                symbolReplacements.put(original, newReplacement);
+                return newReplacement;
+            }
+
+            @Override
+            public Node leaveIdentNode(final IdentNode identNode) {
+                final Symbol oldSymbol = identNode.getSymbol();
+                if (oldSymbol != null) {
+                    final Symbol replacement = getReplacement(oldSymbol);
+                    return identNode.setSymbol(replacement);
+                }
+                return identNode;
+            }
+
+            @Override
+            public Node leaveForNode(final ForNode forNode) {
+                return ensureUniqueLabels(forNode.setIterator(lc, getReplacement(forNode.getIterator())));
+            }
+
+            @Override
+            public Node leaveSwitchNode(final SwitchNode switchNode) {
+                return ensureUniqueLabels(switchNode.setTag(lc, getReplacement(switchNode.getTag())));
+            }
+
+            @Override
+            public Node leaveTryNode(final TryNode tryNode) {
+                return ensureUniqueLabels(tryNode.setException(lc, getReplacement(tryNode.getException())));
+            }
+
+            @Override
+            public boolean enterBlock(final Block block) {
+                for(final Symbol symbol: block.getSymbols()) {
+                    final Symbol replacement = getReplacement(symbol);
+                    if (blockDefinedSymbols != null) {
+                        blockDefinedSymbols.add(replacement);
+                    }
+                }
+                return true;
+            }
+
+            @Override
+            public Node leaveBlock(final Block block) {
+                return ensureUniqueLabels(block.replaceSymbols(lc, symbolReplacements));
+            }
+
+            @Override
+            public Node leaveFunctionNode(final FunctionNode functionNode) {
+                return functionNode.setParameters(lc, functionNode.visitParameters(this));
+            }
+
+            @Override
+            protected Node leaveDefault(final Node node) {
+                return ensureUniqueLabels(node);
+            };
+
+            private Node ensureUniqueLabels(final Node node) {
+                // If we're returning a cached AST, we must also ensure unique labels
+                return cached ? node.ensureUniqueLabels(lc) : node;
+            }
+        });
+
+        if (blockDefinedSymbols != null) {
+            // Mark all symbols not defined in blocks as globals
+            Block newBody = null;
+            for(final Symbol symbol: symbolReplacements.values()) {
+                if(!blockDefinedSymbols.contains(symbol)) {
+                    assert symbol.isScope(); // must be scope
+                    assert externalScopeDepths.containsKey(symbol.getName()); // must be known to us as an external
+                    // Register it in the function body symbol table as a new global symbol
+                    symbol.setFlags((symbol.getFlags() & ~Symbol.KINDMASK) | Symbol.IS_GLOBAL);
+                    if (newBody == null) {
+                        newBody = newFn.getBody().copyWithNewSymbols();
+                        newFn = newFn.setBody(null, newBody);
+                    }
+                    assert newBody.getExistingSymbol(symbol.getName()) == null; // must not be defined in the body already
+                    newBody.putSymbol(symbol);
+                }
+            }
+        }
+        return newFn.setCached(null);
+    }
+
+    private boolean getFunctionFlag(final int flag) {
+        return (functionFlags & flag) != 0;
+    }
+
+    private boolean isProgram() {
+        return getFunctionFlag(FunctionNode.IS_PROGRAM);
+    }
+
+    TypeMap typeMap(final MethodType fnCallSiteType) {
+        if (fnCallSiteType == null) {
+            return null;
+        }
+
+        if (CompiledFunction.isVarArgsType(fnCallSiteType)) {
+            return null;
+        }
+
+        return new TypeMap(functionNodeId, explicitParams(fnCallSiteType), needsCallee());
+    }
+
+    private static ScriptObject newLocals(final ScriptObject runtimeScope) {
+        final ScriptObject locals = Global.newEmptyInstance();
+        locals.setProto(runtimeScope);
+        return locals;
+    }
+
+    private Compiler getCompiler(final FunctionNode fn, final MethodType actualCallSiteType, final ScriptObject runtimeScope) {
+        return getCompiler(fn, actualCallSiteType, newLocals(runtimeScope), null, null);
+    }
+
+    /**
+     * Returns a code installer for installing new code. If we're using either optimistic typing or loader-per-compile,
+     * then asks for a code installer with a new class loader; otherwise just uses the current installer. We use
+     * a new class loader with optimistic typing so that deoptimized code can get reclaimed by GC.
+     * @return a code installer for installing new code.
+     */
+    private CodeInstaller getInstallerForNewCode() {
+        final ScriptEnvironment env = installer.getContext().getEnv();
+        return env._optimistic_types || env._loader_per_compile ? installer.getOnDemandCompilationInstaller() : installer;
+    }
+
+    Compiler getCompiler(final FunctionNode functionNode, final MethodType actualCallSiteType,
+            final ScriptObject runtimeScope, final Map<Integer, Type> invalidatedProgramPoints,
+            final int[] continuationEntryPoints) {
+        final TypeMap typeMap = typeMap(actualCallSiteType);
+        final Type[] paramTypes = typeMap == null ? null : typeMap.getParameterTypes(functionNodeId);
+        final Object typeInformationFile = OptimisticTypesPersistence.getLocationDescriptor(source, functionNodeId, paramTypes);
+        return Compiler.forOnDemandCompilation(
+                getInstallerForNewCode(),
+                functionNode.getSource(),  // source
+                isStrict() | functionNode.isStrict(), // is strict
+                this,       // compiledFunction, i.e. this RecompilableScriptFunctionData
+                typeMap,    // type map
+                getEffectiveInvalidatedProgramPoints(invalidatedProgramPoints, typeInformationFile), // invalidated program points
+                typeInformationFile,
+                continuationEntryPoints, // continuation entry points
+                runtimeScope); // runtime scope
+    }
+
+    /**
+     * If the function being compiled already has its own invalidated program points map, use it. Otherwise, attempt to
+     * load invalidated program points map from the persistent type info cache.
+     * @param invalidatedProgramPoints the function's current invalidated program points map. Null if the function
+     * doesn't have it.
+     * @param typeInformationFile the object describing the location of the persisted type information.
+     * @return either the existing map, or a loaded map from the persistent type info cache, or a new empty map if
+     * neither an existing map or a persistent cached type info is available.
+     */
+    @SuppressWarnings("unused")
+    private static Map<Integer, Type> getEffectiveInvalidatedProgramPoints(
+            final Map<Integer, Type> invalidatedProgramPoints, final Object typeInformationFile) {
+        if(invalidatedProgramPoints != null) {
+            return invalidatedProgramPoints;
+        }
+        final Map<Integer, Type> loadedProgramPoints = OptimisticTypesPersistence.load(typeInformationFile);
+        return loadedProgramPoints != null ? loadedProgramPoints : new TreeMap<Integer, Type>();
+    }
+
+    private FunctionInitializer compileTypeSpecialization(final MethodType actualCallSiteType, final ScriptObject runtimeScope, final boolean persist) {
+        // We're creating an empty script object for holding local variables. AssignSymbols will populate it with
+        // explicit Undefined values for undefined local variables (see AssignSymbols#defineSymbol() and
+        // CompilationEnvironment#declareLocalSymbol()).
+
+        if (log.isEnabled()) {
+            log.info("Parameter type specialization of '", functionName, "' signature: ", actualCallSiteType);
+        }
+
+        final boolean persistentCache = persist && usePersistentCodeCache();
+        String cacheKey = null;
+        if (persistentCache) {
+            final TypeMap typeMap = typeMap(actualCallSiteType);
+            final Type[] paramTypes = typeMap == null ? null : typeMap.getParameterTypes(functionNodeId);
+            cacheKey = CodeStore.getCacheKey(functionNodeId, paramTypes);
+            final CodeInstaller newInstaller = getInstallerForNewCode();
+            final StoredScript script = newInstaller.loadScript(source, cacheKey);
+
+            if (script != null) {
+                Compiler.updateCompilationId(script.getCompilationId());
+                return script.installFunction(this, newInstaller);
+            }
+        }
+
+        final FunctionNode fn = reparse();
+        final Compiler compiler = getCompiler(fn, actualCallSiteType, runtimeScope);
+        final FunctionNode compiledFn = compiler.compile(fn,
+                fn.isCached() ? CompilationPhases.COMPILE_ALL_CACHED : CompilationPhases.COMPILE_ALL);
+
+        if (persist && !compiledFn.hasApplyToCallSpecialization()) {
+            compiler.persistClassInfo(cacheKey, compiledFn);
+        }
+        return new FunctionInitializer(compiledFn, compiler.getInvalidatedProgramPoints());
+    }
+
+    boolean usePersistentCodeCache() {
+        return installer != null && installer.getContext().getEnv()._persistent_cache;
+    }
+
+    private MethodType explicitParams(final MethodType callSiteType) {
+        if (CompiledFunction.isVarArgsType(callSiteType)) {
+            return null;
+        }
+
+        final MethodType noCalleeThisType = callSiteType.dropParameterTypes(0, 2); // (callee, this) is always in call site type
+        final int callSiteParamCount = noCalleeThisType.parameterCount();
+
+        // Widen parameters of reference types to Object as we currently don't care for specialization among reference
+        // types. E.g. call site saying (ScriptFunction, Object, String) should still link to (ScriptFunction, Object, Object)
+        final Class<?>[] paramTypes = noCalleeThisType.parameterArray();
+        boolean changed = false;
+        for (int i = 0; i < paramTypes.length; ++i) {
+            final Class<?> paramType = paramTypes[i];
+            if (!(paramType.isPrimitive() || paramType == Object.class)) {
+                paramTypes[i] = Object.class;
+                changed = true;
+            }
+        }
+        final MethodType generalized = changed ? MethodType.methodType(noCalleeThisType.returnType(), paramTypes) : noCalleeThisType;
+
+        if (callSiteParamCount < getArity()) {
+            return generalized.appendParameterTypes(Collections.<Class<?>>nCopies(getArity() - callSiteParamCount, Object.class));
+        }
+        return generalized;
+    }
+
+    private FunctionNode extractFunctionFromScript(final FunctionNode script) {
+        final Set<FunctionNode> fns = new HashSet<>();
+        script.getBody().accept(new SimpleNodeVisitor() {
+            @Override
+            public boolean enterFunctionNode(final FunctionNode fn) {
+                fns.add(fn);
+                return false;
+            }
+        });
+        assert fns.size() == 1 : "got back more than one method in recompilation";
+        final FunctionNode f = fns.iterator().next();
+        assert f.getId() == functionNodeId;
+        if (!getFunctionFlag(FunctionNode.IS_DECLARED) && f.isDeclared()) {
+            return f.clearFlag(null, FunctionNode.IS_DECLARED);
+        }
+        return f;
+    }
+
+    private void logLookup(final boolean shouldLog, final MethodType targetType) {
+        if (shouldLog && log.isEnabled()) {
+            log.info("Looking up ", DebugLogger.quote(functionName), " type=", targetType);
+        }
+    }
+
+    private MethodHandle lookup(final FunctionInitializer fnInit, final boolean shouldLog) {
+        final MethodType type = fnInit.getMethodType();
+        logLookup(shouldLog, type);
+        return lookupCodeMethod(fnInit.getCode(), type);
+    }
+
+    MethodHandle lookup(final FunctionNode fn) {
+        final MethodType type = new FunctionSignature(fn).getMethodType();
+        logLookup(true, type);
+        return lookupCodeMethod(fn.getCompileUnit().getCode(), type);
+    }
+
+    MethodHandle lookupCodeMethod(final Class<?> codeClass, final MethodType targetType) {
+        return MH.findStatic(LOOKUP, codeClass, functionName, targetType);
+    }
+
+    /**
+     * Initializes this function data with the eagerly generated version of the code. This method can only be invoked
+     * by the compiler internals in Nashorn and is public for implementation reasons only. Attempting to invoke it
+     * externally will result in an exception.
+     *
+     * @param functionNode FunctionNode for this data
+     */
+    public void initializeCode(final FunctionNode functionNode) {
+        // Since the method is public, we double-check that we aren't invoked with an inappropriate compile unit.
+        if (!code.isEmpty() || functionNode.getId() != functionNodeId || !functionNode.getCompileUnit().isInitializing(this, functionNode)) {
+            throw new IllegalStateException(name);
+        }
+        addCode(lookup(functionNode), null, null, functionNode.getFlags());
+    }
+
+    /**
+     * Initializes this function with the given function code initializer.
+     * @param initializer function code initializer
+     */
+    void initializeCode(final FunctionInitializer initializer) {
+        addCode(lookup(initializer, true), null, null, initializer.getFlags());
+    }
+
+    private CompiledFunction addCode(final MethodHandle target, final Map<Integer, Type> invalidatedProgramPoints,
+                                     final MethodType callSiteType, final int fnFlags) {
+        final CompiledFunction cfn = new CompiledFunction(target, this, invalidatedProgramPoints, callSiteType, fnFlags);
+        assert noDuplicateCode(cfn) : "duplicate code";
+        code.add(cfn);
+        return cfn;
+    }
+
+    /**
+     * Add code with specific call site type. It will adapt the type of the looked up method handle to fit the call site
+     * type. This is necessary because even if we request a specialization that takes an "int" parameter, we might end
+     * up getting one that takes a "double" etc. because of internal function logic causes widening (e.g. assignment of
+     * a wider value to the parameter variable). However, we use the method handle type for matching subsequent lookups
+     * for the same specialization, so we must adapt the handle to the expected type.
+     * @param fnInit the function
+     * @param callSiteType the call site type
+     * @return the compiled function object, with its type matching that of the call site type.
+     */
+    private CompiledFunction addCode(final FunctionInitializer fnInit, final MethodType callSiteType) {
+        if (isVariableArity()) {
+            return addCode(lookup(fnInit, true), fnInit.getInvalidatedProgramPoints(), callSiteType, fnInit.getFlags());
+        }
+
+        final MethodHandle handle = lookup(fnInit, true);
+        final MethodType fromType = handle.type();
+        MethodType toType = needsCallee(fromType) ? callSiteType.changeParameterType(0, ScriptFunction.class) : callSiteType.dropParameterTypes(0, 1);
+        toType = toType.changeReturnType(fromType.returnType());
+
+        final int toCount = toType.parameterCount();
+        final int fromCount = fromType.parameterCount();
+        final int minCount = Math.min(fromCount, toCount);
+        for(int i = 0; i < minCount; ++i) {
+            final Class<?> fromParam = fromType.parameterType(i);
+            final Class<?>   toParam =   toType.parameterType(i);
+            // If method has an Object parameter, but call site had String, preserve it as Object. No need to narrow it
+            // artificially. Note that this is related to how CompiledFunction.matchesCallSite() works, specifically
+            // the fact that various reference types compare to equal (see "fnType.isEquivalentTo(csType)" there).
+            if (fromParam != toParam && !fromParam.isPrimitive() && !toParam.isPrimitive()) {
+                assert fromParam.isAssignableFrom(toParam);
+                toType = toType.changeParameterType(i, fromParam);
+            }
+        }
+        if (fromCount > toCount) {
+            toType = toType.appendParameterTypes(fromType.parameterList().subList(toCount, fromCount));
+        } else if (fromCount < toCount) {
+            toType = toType.dropParameterTypes(fromCount, toCount);
+        }
+
+        return addCode(lookup(fnInit, false).asType(toType), fnInit.getInvalidatedProgramPoints(), callSiteType, fnInit.getFlags());
+    }
+
+    /**
+     * Returns the return type of a function specialization for particular parameter types.<br>
+     * <b>Be aware that the way this is implemented, it forces full materialization (compilation and installation) of
+     * code for that specialization.</b>
+     * @param callSiteType the parameter types at the call site. It must include the mandatory {@code callee} and
+     * {@code this} parameters, so it needs to start with at least {@code ScriptFunction.class} and
+     * {@code Object.class} class. Since the return type of the function is calculated from the code itself, it is
+     * irrelevant and should be set to {@code Object.class}.
+     * @param runtimeScope a current runtime scope. Can be null but when it's present it will be used as a source of
+     * current runtime values that can improve the compiler's type speculations (and thus reduce the need for later
+     * recompilations) if the specialization is not already present and thus needs to be freshly compiled.
+     * @return the return type of the function specialization.
+     */
+    public Class<?> getReturnType(final MethodType callSiteType, final ScriptObject runtimeScope) {
+        return getBest(callSiteType, runtimeScope, CompiledFunction.NO_FUNCTIONS).type().returnType();
+    }
+
+    @Override
+    synchronized CompiledFunction getBest(final MethodType callSiteType, final ScriptObject runtimeScope, final Collection<CompiledFunction> forbidden, final boolean linkLogicOkay) {
+        assert isValidCallSite(callSiteType) : callSiteType;
+
+        CompiledFunction existingBest = pickFunction(callSiteType, false);
+        if (existingBest == null) {
+            existingBest = pickFunction(callSiteType, true); // try vararg last
+        }
+        if (existingBest == null) {
+            existingBest = addCode(compileTypeSpecialization(callSiteType, runtimeScope, true), callSiteType);
+        }
+
+        assert existingBest != null;
+
+        //if the best one is an apply to call, it has to match the callsite exactly
+        //or we need to regenerate
+        if (existingBest.isApplyToCall()) {
+            final CompiledFunction best = lookupExactApplyToCall(callSiteType);
+            if (best != null) {
+                return best;
+            }
+
+            // special case: we had an apply to call, but we failed to make it fit.
+            // Try to generate a specialized one for this callsite. It may
+            // be another apply to call specialization, or it may not, but whatever
+            // it is, it is a specialization that is guaranteed to fit
+            existingBest = addCode(compileTypeSpecialization(callSiteType, runtimeScope, false), callSiteType);
+        }
+
+        return existingBest;
+    }
+
+    @Override
+    public boolean needsCallee() {
+        return getFunctionFlag(FunctionNode.NEEDS_CALLEE);
+    }
+
+    /**
+     * Returns the {@link FunctionNode} flags associated with this function data.
+     * @return the {@link FunctionNode} flags associated with this function data.
+     */
+    public int getFunctionFlags() {
+        return functionFlags;
+    }
+
+    @Override
+    MethodType getGenericType() {
+        // 2 is for (callee, this)
+        if (isVariableArity()) {
+            return MethodType.genericMethodType(2, true);
+        }
+        return MethodType.genericMethodType(2 + getArity());
+    }
+
+    /**
+     * Return the function node id.
+     * @return the function node id
+     */
+    public int getFunctionNodeId() {
+        return functionNodeId;
+    }
+
+    /**
+     * Get the source for the script
+     * @return source
+     */
+    public Source getSource() {
+        return source;
+    }
+
+    /**
+     * Return a script function data based on a function id, either this function if
+     * the id matches or a nested function based on functionId. This goes down into
+     * nested functions until all leaves are exhausted.
+     *
+     * @param functionId function id
+     * @return script function data or null if invalid id
+     */
+    public RecompilableScriptFunctionData getScriptFunctionData(final int functionId) {
+        if (functionId == functionNodeId) {
+            return this;
+        }
+        RecompilableScriptFunctionData data;
+
+        data = nestedFunctions == null ? null : nestedFunctions.get(functionId);
+        if (data != null) {
+            return data;
+        }
+        for (final RecompilableScriptFunctionData ndata : nestedFunctions.values()) {
+            data = ndata.getScriptFunctionData(functionId);
+            if (data != null) {
+                return data;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Check whether a certain name is a global symbol, i.e. only exists as defined
+     * in outermost scope and not shadowed by being parameter or assignment in inner
+     * scopes
+     *
+     * @param functionNode function node to check
+     * @param symbolName symbol name
+     * @return true if global symbol
+     */
+    public boolean isGlobalSymbol(final FunctionNode functionNode, final String symbolName) {
+        RecompilableScriptFunctionData data = getScriptFunctionData(functionNode.getId());
+        assert data != null;
+
+        do {
+            if (data.hasInternalSymbol(symbolName)) {
+                return false;
+            }
+            data = data.getParent();
+        } while(data != null);
+
+        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;
+    }
+
+    // Make sure code does not contain a compiled function with the same signature as compiledFunction
+    private boolean noDuplicateCode(final CompiledFunction compiledFunction) {
+        for (final CompiledFunction cf : code) {
+            if (cf.type().equals(compiledFunction.type())) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private void writeObject(final ObjectOutputStream out) throws IOException {
+        final Object localCachedAst = cachedAst;
+        out.defaultWriteObject();
+        // We need to persist SerializedAst for split functions as they can't reparse the source code.
+        if (localCachedAst instanceof SerializedAst) {
+            out.writeObject(localCachedAst);
+        } else {
+            out.writeObject(null);
+        }
+    }
+
+    private void readObject(final java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
+        in.defaultReadObject();
+        cachedAst = in.readObject();
+        createLogger();
+    }
+
+    private void createLogger() {
+        log = initLogger(Context.getContextTrusted());
+    }
+}