Mercurial > jdk8-mips64-public > nashorn / file revision

 /*

  * 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

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 package jdk.nashorn.internal.runtime;

 import static jdk.nashorn.internal.lookup.Lookup.MH;

 import java.lang.invoke.MethodHandle;

 import java.lang.invoke.MethodHandles;

 import java.lang.invoke.MethodType;

 import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.LinkedList;

 import jdk.internal.dynalink.support.NameCodec;

 import jdk.nashorn.internal.codegen.Compiler;

 import jdk.nashorn.internal.codegen.CompilerConstants;

 import jdk.nashorn.internal.codegen.FunctionSignature;

 import jdk.nashorn.internal.codegen.types.Type;

 import jdk.nashorn.internal.ir.FunctionNode;

 import jdk.nashorn.internal.ir.FunctionNode.CompilationState;

 import jdk.nashorn.internal.parser.Token;

 import jdk.nashorn.internal.parser.TokenType;

 /**

  * 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}

  */

 public final class RecompilableScriptFunctionData extends ScriptFunctionData {

     /** FunctionNode with the code for this ScriptFunction */

     private FunctionNode functionNode;

     /** Source from which FunctionNode was parsed. */

     private final Source source;

     /** Token of this function within the source. */

     private final long token;

     /** Allocator map from makeMap() */

     private final PropertyMap allocatorMap;

     /** Code installer used for all further recompilation/specialization of this ScriptFunction */

     private CodeInstaller<ScriptEnvironment> installer;

     /** Name of class where allocator function resides */

     private final String allocatorClassName;

     /** lazily generated allocator */

     private MethodHandle allocator;

     private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();

     /**

      * Used for specialization based on runtime arguments. Whenever we specialize on

      * callsite parameter types at runtime, we need to use a parameter type guard to

      * ensure that the specialized version of the script function continues to be

      * applicable for a particular callsite *

      */

     private static final MethodHandle PARAM_TYPE_GUARD = findOwnMH("paramTypeGuard", boolean.class, Type[].class,  Object[].class);

     /**

      * It is usually a good gamble whever we detect a runtime callsite with a double

      * (or java.lang.Number instance) to specialize the parameter to an integer, if the

      * parameter in question can be represented as one. The double typically only exists

      * because the compiler doesn't know any better than "a number type" and conservatively

      * picks doubles when it can't prove that an integer addition wouldn't overflow

      */

     private static final MethodHandle ENSURE_INT = findOwnMH("ensureInt", int.class, Object.class);

     /**

      * 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 allocatorClassName name of our allocator class, will be looked up dynamically if used as a constructor

      * @param allocatorMap       allocator map to seed instances with, when constructing

      */

     public RecompilableScriptFunctionData(final FunctionNode functionNode, final CodeInstaller<ScriptEnvironment> installer, final String allocatorClassName, final PropertyMap allocatorMap) {

         super(functionName(functionNode),

               functionNode.getParameters().size(),

               functionNode.isStrict(),

               false,

               true);

         this.functionNode       = functionNode;

         this.source             = functionNode.getSource();

         this.token              = tokenFor(functionNode);

         this.installer          = installer;

         this.allocatorClassName = allocatorClassName;

         this.allocatorMap       = allocatorMap;

     }

     @Override

     String toSource() {

         if (source != null && token != 0) {

             return source.getString(Token.descPosition(token), Token.descLength(token));

         }

         return "function " + (name == null ? "" : name) + "() { [native code] }";

     }

     @Override

     public String toString() {

         final StringBuilder sb = new StringBuilder();

         if (source != null) {

             sb.append(source.getName())

                 .append(':')

                 .append(functionNode.getLineNumber())

                 .append(' ');

         }

         return sb.toString() + super.toString();

     }

     private static String functionName(final FunctionNode fn) {

         if (fn.isAnonymous()) {

             return "";

         } else {

             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(4); // 4 is "get " or "set "

             } else {

                 return fn.getIdent().getName();

             }

         }

     }

     private static long tokenFor(final FunctionNode fn) {

         final int  position   = Token.descPosition(fn.getFirstToken());

         final int  length     = Token.descPosition(fn.getLastToken()) - position + Token.descLength(fn.getLastToken());

         return Token.toDesc(TokenType.FUNCTION, position, length);

     }

     @Override

     ScriptObject allocate() {

         try {

             ensureHasAllocator(); //if allocatorClass name is set to null (e.g. for bound functions) we don't even try

             return allocator == null ? null : (ScriptObject)allocator.invokeExact(allocatorMap);

         } catch (final RuntimeException | Error e) {

             throw e;

         } catch (final Throwable t) {

             throw new RuntimeException(t);

         }

     }

     private void ensureHasAllocator() throws ClassNotFoundException {

         if (allocator == null && allocatorClassName != null) {

             this.allocator = MH.findStatic(LOOKUP, Context.forStructureClass(allocatorClassName), CompilerConstants.ALLOCATE.symbolName(), MH.type(ScriptObject.class, PropertyMap.class));

         }

     }

     @Override

     protected synchronized void ensureCodeGenerated() {

          if (!code.isEmpty()) {

              return; // nothing to do, we have code, at least some.

          }

          if (functionNode.isLazy()) {

              Compiler.LOG.info("Trampoline hit: need to do lazy compilation of '", functionNode.getName(), "'");

              final Compiler compiler = new Compiler(installer);

              functionNode = compiler.compile(functionNode);

              assert !functionNode.isLazy();

              compiler.install(functionNode);

              /*

               * We don't need to update any flags - varArgs and needsCallee are instrincic

               * in the function world we need to get a destination node from the compile instead

               * and replace it with our function node. TODO

               */

          }

          /*

           * We can't get to this program point unless we have bytecode, either from

           * eager compilation or from running a lazy compile on the lines above

           */

          assert functionNode.hasState(CompilationState.EMITTED) : functionNode.getName() + " " + functionNode.getState() + " " + Debug.id(functionNode);

          // code exists - look it up and add it into the automatically sorted invoker list

          addCode(functionNode);

          if (! functionNode.canSpecialize()) {

              // allow GC to claim IR stuff that is not needed anymore

              functionNode = null;

              installer = null;

          }

     }

     private MethodHandle addCode(final FunctionNode fn) {

         return addCode(fn, null, null, null);

     }

     private MethodHandle addCode(final FunctionNode fn, final MethodType runtimeType, final MethodHandle guard, final MethodHandle fallback) {

         final MethodType targetType = new FunctionSignature(fn).getMethodType();

         MethodHandle target =

             MH.findStatic(

                     LOOKUP,

                     fn.getCompileUnit().getCode(),

                     fn.getName(),

                     targetType);

         /*

          * For any integer argument. a double that is representable as an integer is OK.

          * otherwise the guard would have failed. in that case introduce a filter that

          * casts the double to an integer, which we know will preserve all precision.

          */

         for (int i = 0; i < targetType.parameterCount(); i++) {

             if (targetType.parameterType(i) == int.class) {

                 //representable as int

                 target = MH.filterArguments(target, i, ENSURE_INT);

             }

         }

         MethodHandle mh = target;

         if (guard != null) {

             mh = MH.guardWithTest(MH.asCollector(guard, Object[].class, target.type().parameterCount()), MH.asType(target, fallback.type()), fallback);

         }

         final CompiledFunction cf = new CompiledFunction(runtimeType == null ? targetType : runtimeType, mh);

         code.add(cf);

         return cf.getInvoker();

     }

     private static Type runtimeType(final Object arg) {

         if (arg == null) {

             return Type.OBJECT;

         }

         final Class<?> clazz = arg.getClass();

         assert !clazz.isPrimitive() : "always boxed";

         if (clazz == Double.class) {

             return JSType.isRepresentableAsInt((double)arg) ? Type.INT : Type.NUMBER;

         } else if (clazz == Integer.class) {

             return Type.INT;

         } else if (clazz == Long.class) {

             return Type.LONG;

         } else if (clazz == String.class) {

             return Type.STRING;

         }

         return Type.OBJECT;

     }

     private static boolean canCoerce(final Object arg, final Type type) {

         Type argType = runtimeType(arg);

         if (Type.widest(argType, type) == type || arg == ScriptRuntime.UNDEFINED) {

             return true;

         }

         System.err.println(arg + " does not fit in "+ argType + " " + type + " " + arg.getClass());

         new Throwable().printStackTrace();

         return false;

     }

     @SuppressWarnings("unused")

     private static boolean paramTypeGuard(final Type[] paramTypes, final Object... args) {

         final int length = args.length;

         assert args.length >= paramTypes.length;

         //i==start, skip the this, callee params etc

         int start = args.length - paramTypes.length;

         for (int i = start; i < args.length; i++) {

             final Object arg = args[i];

             if (!canCoerce(arg, paramTypes[i - start])) {

                 return false;

             }

         }

         return true;

     }

     @SuppressWarnings("unused")

     private static int ensureInt(final Object arg) {

         if (arg instanceof Number) {

             return ((Number)arg).intValue();

         } else if (arg instanceof Undefined) {

             return 0;

         }

         throw new AssertionError(arg);

     }

     /**

      * Given the runtime callsite args, compute a method type that is equivalent to what

      * was passed - this is typically a lot more specific that what the compiler has been

      * able to deduce

      * @param callSiteType callsite type for the compiled callsite target

      * @param args runtime arguments to the compiled callsite target

      * @return adjusted method type, narrowed as to conform to runtime callsite type instead

      */

     private static MethodType runtimeType(final MethodType callSiteType, final Object[] args) {

         if (args == null) {

             //for example bound, or otherwise runtime arguments to callsite unavailable, then

             //do not change the type

             return callSiteType;

         }

         final Class<?>[] paramTypes = new Class<?>[callSiteType.parameterCount()];

         final int        start      = args.length - callSiteType.parameterCount();

         for (int i = start; i < args.length; i++) {

             paramTypes[i - start] = runtimeType(args[i]).getTypeClass();

         }

         return MH.type(callSiteType.returnType(), paramTypes);

     }

     private static ArrayList<Type> runtimeType(final MethodType mt) {

         final ArrayList<Type> type = new ArrayList<>();

         for (int i = 0; i < mt.parameterCount(); i++) {

             type.add(Type.typeFor(mt.parameterType(i)));

         }

         return type;

     }

     @Override

     synchronized MethodHandle getBestInvoker(final MethodType callSiteType, final Object[] args) {

         final MethodType runtimeType = runtimeType(callSiteType, args);

         assert runtimeType.parameterCount() == callSiteType.parameterCount();

         final MethodHandle mh = super.getBestInvoker(runtimeType, args);

         /*

          * Not all functions can be specialized, for example, if we deemed memory

          * footprint too large to store a parse snapshot, or if it is meaningless

          * to do so, such as e.g. for runScript

          */

         if (functionNode == null || !functionNode.canSpecialize()) {

             return mh;

         }

         /*

          * Check if best invoker is equally specific or more specific than runtime

          * type. In that case, we don't need further specialization, but can use

          * whatever we have already. We know that it will match callSiteType, or it

          * would not have been returned from getBestInvoker

          */

         if (!code.isLessSpecificThan(runtimeType)) {

             return mh;

         }

         int i;

         final FunctionNode snapshot = functionNode.getSnapshot();

         assert snapshot != null;

         /*

          * Create a list of the arg types that the compiler knows about

          * typically, the runtime args are a lot more specific, and we should aggressively

          * try to use those whenever possible

          * We WILL try to make an aggressive guess as possible, and add guards if needed.

          * For example, if the compiler can deduce that we have a number type, but the runtime

          * passes and int, we might still want to keep it an int, and the gamble to

          * check that whatever is passed is int representable usually pays off

          * If the compiler only knows that a parameter is an "Object", it is still worth

          * it to try to specialize it by looking at the runtime arg.

          */

         final LinkedList<Type> compileTimeArgs = new LinkedList<>();

         for (i = callSiteType.parameterCount() - 1; i >= 0 && compileTimeArgs.size() < snapshot.getParameters().size(); i--) {

             compileTimeArgs.addFirst(Type.typeFor(callSiteType.parameterType(i)));

         }

         /*

          * The classes known at compile time are a safe to generate as primitives without parameter guards

          * But the classes known at runtime (if more specific than compile time types) are safe to generate as primitives

          * IFF there are parameter guards

          */

         MethodHandle guard = null;

         final ArrayList<Type> runtimeParamTypes = runtimeType(runtimeType);

         while (runtimeParamTypes.size() > functionNode.getParameters().size()) {

             runtimeParamTypes.remove(0);

         }

         for (i = 0; i < compileTimeArgs.size(); i++) {

             final Type rparam = Type.typeFor(runtimeType.parameterType(i));

             final Type cparam = compileTimeArgs.get(i);

             if (cparam.isObject() && !rparam.isObject()) {

                 //check that the runtime object is still coercible to the runtime type, because compiler can't prove it's always primitive

                 if (guard == null) {

                     guard = MH.insertArguments(PARAM_TYPE_GUARD, 0, (Object)runtimeParamTypes.toArray(new Type[runtimeParamTypes.size()]));

                 }

             }

         }

         Compiler.LOG.info("Callsite specialized ", name, " runtimeType=", runtimeType, " parameters=", snapshot.getParameters(), " args=", Arrays.asList(args));

         assert snapshot != null;

         assert snapshot != functionNode;

         final Compiler compiler = new Compiler(installer);

         final FunctionNode compiledSnapshot = compiler.compile(

             snapshot.setHints(

                 null,

                 new Compiler.Hints(runtimeParamTypes.toArray(new Type[runtimeParamTypes.size()]))));

         /*

          * No matter how narrow your types were, they can never be narrower than Attr during recompile made them. I.e. you

          * can put an int into the function here, if you see it as a runtime type, but if the function uses a multiplication

          * on it, it will still need to be a double. At least until we have overflow checks. Similarly, if an int is

          * passed but it is used as a string, it makes no sense to make the parameter narrower than Object. At least until

          * the "different types for one symbol in difference places" work is done

          */

         compiler.install(compiledSnapshot);

         return addCode(compiledSnapshot, runtimeType, guard, mh);

     }

     private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {

         return MH.findStatic(MethodHandles.lookup(), RecompilableScriptFunctionData.class, name, MH.type(rtype, types));

     }

 }