src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/codegen/SharedScopeCall.java - platform/libcore - Git at Google

 /*
  * 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 static jdk.nashorn.internal.codegen.CompilerConstants.virtualCallNoLookup;
 import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.CALLSITE_OPTIMISTIC;

 import java.util.Arrays;
 import java.util.EnumSet;
 import jdk.nashorn.internal.codegen.types.Type;
 import jdk.nashorn.internal.ir.Symbol;
 import jdk.nashorn.internal.runtime.ScriptObject;
 import jdk.nashorn.internal.runtime.UnwarrantedOptimismException;
 import jdk.nashorn.internal.runtime.options.Options;

 /**
  * A scope call or get operation that can be shared by several call sites. This generates a static
  * method that wraps the invokedynamic instructions to get or call scope variables.
  * The reason for this is to reduce memory footprint and initial linking overhead of huge scripts.
  *
  * <p>Static methods generated by this class expect three parameters in addition to the parameters of the
  * function call: The current scope object, the depth of the target scope relative to the scope argument,
  * and the program point in case the target operation is optimistic.</p>
  *
  * <p>Optimistic operations are called with program point <code>0</code>. If an <code>UnwarrentedOptimismException</code>
  * is thrown, it is caught by the shared call method and rethrown with the program point of the invoking call site.</p>
  *
  * <p>Shared scope calls are not used if the scope contains a <code>with</code> statement or a call to
  * <code>eval</code>.</p>
  */
 class SharedScopeCall {

     /**
      * Threshold for using shared scope function calls.
      */
     public static final int SHARED_CALL_THRESHOLD =
             Options.getIntProperty("nashorn.shared.scope.call.threshold", 5);
     /**
      * Threshold for using shared scope variable getter. This is higher than for calls as lower values
      * degrade performance on many scripts.
      */
     public static final int SHARED_GET_THRESHOLD  =
             Options.getIntProperty("nashorn.shared.scope.get.threshold", 100);

     private static final CompilerConstants.Call REPLACE_PROGRAM_POINT = virtualCallNoLookup(
                     UnwarrantedOptimismException.class, "replaceProgramPoint",
                     UnwarrantedOptimismException.class, int.class);

     /** Number of fixed parameters */
     private static final int FIXED_PARAM_COUNT = 3;

     private final Type valueType;
     private final Symbol symbol;
     private final Type returnType;
     private final Type[] paramTypes;
     private final int flags;
     private final boolean isCall;
     private final boolean isOptimistic;
     private CompileUnit compileUnit;
     private String methodName;
     private String staticSignature;

     /**
      * Constructor.
      *
      * @param symbol the symbol
      * @param valueType the type of the value
      * @param returnType the return type
      * @param paramTypes the function parameter types
      * @param flags the callsite flags
      * @param isOptimistic whether target call is optimistic and we need to handle UnwarrentedOptimismException
      */
     SharedScopeCall(final Symbol symbol, final Type valueType, final Type returnType, final Type[] paramTypes,
                     final int flags, final boolean isOptimistic) {
         this.symbol = symbol;
         this.valueType = valueType;
         this.returnType = returnType;
         this.paramTypes = paramTypes;
         this.flags = flags;
         this.isCall = paramTypes != null; // If paramTypes is not null this is a call, otherwise it's just a get.
         this.isOptimistic = isOptimistic;
     }

     @Override
     public int hashCode() {
         return symbol.hashCode() ^ returnType.hashCode() ^ Arrays.hashCode(paramTypes) ^ flags ^ Boolean.hashCode(isOptimistic);
     }

     @Override
     public boolean equals(final Object obj) {
         if (obj instanceof SharedScopeCall) {
             final SharedScopeCall c = (SharedScopeCall) obj;
             return symbol.equals(c.symbol)
                     && flags == c.flags
                     && returnType.equals(c.returnType)
                     && Arrays.equals(paramTypes, c.paramTypes)
                     && isOptimistic == c.isOptimistic;
         }
         return false;
     }

     /**
      * Set the compile unit and method name.
      * @param compileUnit the compile unit
      * @param methodName the method name
      */
     protected void setClassAndName(final CompileUnit compileUnit, final String methodName) {
         this.compileUnit = compileUnit;
         this.methodName  = methodName;
     }

     /**
      * Generate the invoke instruction for this shared scope call.
      * @param method the method emitter
      */
     public void generateInvoke(final MethodEmitter method) {
         method.invokestatic(compileUnit.getUnitClassName(), methodName, getStaticSignature());
     }

     /**
      * Generate the method that implements the scope get or call.
      */
     protected void generateScopeCall() {
         final ClassEmitter classEmitter = compileUnit.getClassEmitter();
         final EnumSet<ClassEmitter.Flag> methodFlags = EnumSet.of(ClassEmitter.Flag.STATIC);

         // This method expects two fixed parameters in addition to any parameters that may be
         // passed on to the function: A ScriptObject representing the caller's current scope object,
         // and an int specifying the distance to the target scope containing the symbol we want to
         // access, or -1 if this is not known at compile time (e.g. because of a "with" or "eval").

         final MethodEmitter method = classEmitter.method(methodFlags, methodName, getStaticSignature());
         method.begin();

         // Load correct scope by calling getProto(int) on the scope argument with the supplied depth argument
         method.load(Type.OBJECT, 0);
         method.load(Type.INT, 1);
         method.invoke(ScriptObject.GET_PROTO_DEPTH);

         assert !isCall || valueType.isObject(); // Callables are always loaded as object

         // Labels for catch of UnsupportedOptimismException
         final Label beginTry;
         final Label endTry;
         final Label catchLabel;

         if(isOptimistic) {
             beginTry = new Label("begin_try");
             endTry = new Label("end_try");
             catchLabel = new Label("catch_label");
             method.label(beginTry);
             method._try(beginTry, endTry, catchLabel, UnwarrantedOptimismException.class, false);
         } else {
             beginTry = endTry = catchLabel = null;
         }

         // If this is an optimistic get we set the optimistic flag but don't set the program point,
         // which implies a program point of 0. If optimism fails we'll replace it with the actual
         // program point which caller supplied as third argument.
         final int getFlags = isOptimistic && !isCall ? flags | CALLSITE_OPTIMISTIC : flags;
         method.dynamicGet(valueType, symbol.getName(), getFlags, isCall, false);

         // If this is a get we're done, otherwise call the value as function.
         if (isCall) {
             method.convert(Type.OBJECT);
             // ScriptFunction will see CALLSITE_SCOPE and will bind scope accordingly.
             method.loadUndefined(Type.OBJECT);
             int slot = FIXED_PARAM_COUNT;
             for (final Type type : paramTypes) {
                 method.load(type, slot);
                 slot += type.getSlots();
             }

             // Same as above, set optimistic flag but leave program point as 0.
             final int callFlags = isOptimistic ? flags | CALLSITE_OPTIMISTIC : flags;

             method.dynamicCall(returnType, 2 + paramTypes.length, callFlags, symbol.getName());

         }

         if (isOptimistic) {
             method.label(endTry);
         }

         method._return(returnType);

         if (isOptimistic) {
             // We caught a UnwarrantedOptimismException, replace 0 program point with actual program point
             method._catch(catchLabel);
             method.load(Type.INT, 2);
             method.invoke(REPLACE_PROGRAM_POINT);
             method.athrow();
         }

         method.end();
     }

     private String getStaticSignature() {
         if (staticSignature == null) {
             if (paramTypes == null) {
                 staticSignature = Type.getMethodDescriptor(returnType, Type.typeFor(ScriptObject.class), Type.INT, Type.INT);
             } else {
                 final Type[] params = new Type[paramTypes.length + FIXED_PARAM_COUNT];
                 params[0] = Type.typeFor(ScriptObject.class);
                 params[1] = Type.INT;
                 params[2] = Type.INT;
                 System.arraycopy(paramTypes, 0, params, FIXED_PARAM_COUNT, paramTypes.length);
                 staticSignature = Type.getMethodDescriptor(returnType, params);
             }
         }
         return staticSignature;
     }

     @Override
     public String toString() {
         return methodName + " " + staticSignature;
     }

 }
	/*
	* 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 static jdk.nashorn.internal.codegen.CompilerConstants.virtualCallNoLookup;
	import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.CALLSITE_OPTIMISTIC;

	import java.util.Arrays;
	import java.util.EnumSet;
	import jdk.nashorn.internal.codegen.types.Type;
	import jdk.nashorn.internal.ir.Symbol;
	import jdk.nashorn.internal.runtime.ScriptObject;
	import jdk.nashorn.internal.runtime.UnwarrantedOptimismException;
	import jdk.nashorn.internal.runtime.options.Options;

	/**
	* A scope call or get operation that can be shared by several call sites. This generates a static
	* method that wraps the invokedynamic instructions to get or call scope variables.
	* The reason for this is to reduce memory footprint and initial linking overhead of huge scripts.
	*
	* <p>Static methods generated by this class expect three parameters in addition to the parameters of the
	* function call: The current scope object, the depth of the target scope relative to the scope argument,
	* and the program point in case the target operation is optimistic.</p>
	*
	* <p>Optimistic operations are called with program point <code>0</code>. If an <code>UnwarrentedOptimismException</code>
	* is thrown, it is caught by the shared call method and rethrown with the program point of the invoking call site.</p>
	*
	* <p>Shared scope calls are not used if the scope contains a <code>with</code> statement or a call to
	* <code>eval</code>.</p>
	*/
	class SharedScopeCall {

	/**
	* Threshold for using shared scope function calls.
	*/
	public static final int SHARED_CALL_THRESHOLD =
	Options.getIntProperty("nashorn.shared.scope.call.threshold", 5);
	/**
	* Threshold for using shared scope variable getter. This is higher than for calls as lower values
	* degrade performance on many scripts.
	*/
	public static final int SHARED_GET_THRESHOLD =
	Options.getIntProperty("nashorn.shared.scope.get.threshold", 100);

	private static final CompilerConstants.Call REPLACE_PROGRAM_POINT = virtualCallNoLookup(
	UnwarrantedOptimismException.class, "replaceProgramPoint",
	UnwarrantedOptimismException.class, int.class);

	/** Number of fixed parameters */
	private static final int FIXED_PARAM_COUNT = 3;

	private final Type valueType;
	private final Symbol symbol;
	private final Type returnType;
	private final Type[] paramTypes;
	private final int flags;
	private final boolean isCall;
	private final boolean isOptimistic;
	private CompileUnit compileUnit;
	private String methodName;
	private String staticSignature;

	/**
	* Constructor.
	*
	* @param symbol the symbol
	* @param valueType the type of the value
	* @param returnType the return type
	* @param paramTypes the function parameter types
	* @param flags the callsite flags
	* @param isOptimistic whether target call is optimistic and we need to handle UnwarrentedOptimismException
	*/
	SharedScopeCall(final Symbol symbol, final Type valueType, final Type returnType, final Type[] paramTypes,
	final int flags, final boolean isOptimistic) {
	this.symbol = symbol;
	this.valueType = valueType;
	this.returnType = returnType;
	this.paramTypes = paramTypes;
	this.flags = flags;
	this.isCall = paramTypes != null; // If paramTypes is not null this is a call, otherwise it's just a get.
	this.isOptimistic = isOptimistic;
	}

	@Override
	public int hashCode() {
	return symbol.hashCode() ^ returnType.hashCode() ^ Arrays.hashCode(paramTypes) ^ flags ^ Boolean.hashCode(isOptimistic);
	}

	@Override
	public boolean equals(final Object obj) {
	if (obj instanceof SharedScopeCall) {
	final SharedScopeCall c = (SharedScopeCall) obj;
	return symbol.equals(c.symbol)
	&& flags == c.flags
	&& returnType.equals(c.returnType)
	&& Arrays.equals(paramTypes, c.paramTypes)
	&& isOptimistic == c.isOptimistic;
	}
	return false;
	}

	/**
	* Set the compile unit and method name.
	* @param compileUnit the compile unit
	* @param methodName the method name
	*/
	protected void setClassAndName(final CompileUnit compileUnit, final String methodName) {
	this.compileUnit = compileUnit;
	this.methodName = methodName;
	}

	/**
	* Generate the invoke instruction for this shared scope call.
	* @param method the method emitter
	*/
	public void generateInvoke(final MethodEmitter method) {
	method.invokestatic(compileUnit.getUnitClassName(), methodName, getStaticSignature());
	}

	/**
	* Generate the method that implements the scope get or call.
	*/
	protected void generateScopeCall() {
	final ClassEmitter classEmitter = compileUnit.getClassEmitter();
	final EnumSet<ClassEmitter.Flag> methodFlags = EnumSet.of(ClassEmitter.Flag.STATIC);

	// This method expects two fixed parameters in addition to any parameters that may be
	// passed on to the function: A ScriptObject representing the caller's current scope object,
	// and an int specifying the distance to the target scope containing the symbol we want to
	// access, or -1 if this is not known at compile time (e.g. because of a "with" or "eval").

	final MethodEmitter method = classEmitter.method(methodFlags, methodName, getStaticSignature());
	method.begin();

	// Load correct scope by calling getProto(int) on the scope argument with the supplied depth argument
	method.load(Type.OBJECT, 0);
	method.load(Type.INT, 1);
	method.invoke(ScriptObject.GET_PROTO_DEPTH);

	assert !isCall \|\| valueType.isObject(); // Callables are always loaded as object

	// Labels for catch of UnsupportedOptimismException
	final Label beginTry;
	final Label endTry;
	final Label catchLabel;

	if(isOptimistic) {
	beginTry = new Label("begin_try");
	endTry = new Label("end_try");
	catchLabel = new Label("catch_label");
	method.label(beginTry);
	method._try(beginTry, endTry, catchLabel, UnwarrantedOptimismException.class, false);
	} else {
	beginTry = endTry = catchLabel = null;
	}

	// If this is an optimistic get we set the optimistic flag but don't set the program point,
	// which implies a program point of 0. If optimism fails we'll replace it with the actual
	// program point which caller supplied as third argument.
	final int getFlags = isOptimistic && !isCall ? flags \| CALLSITE_OPTIMISTIC : flags;
	method.dynamicGet(valueType, symbol.getName(), getFlags, isCall, false);

	// If this is a get we're done, otherwise call the value as function.
	if (isCall) {
	method.convert(Type.OBJECT);
	// ScriptFunction will see CALLSITE_SCOPE and will bind scope accordingly.
	method.loadUndefined(Type.OBJECT);
	int slot = FIXED_PARAM_COUNT;
	for (final Type type : paramTypes) {
	method.load(type, slot);
	slot += type.getSlots();
	}

	// Same as above, set optimistic flag but leave program point as 0.
	final int callFlags = isOptimistic ? flags \| CALLSITE_OPTIMISTIC : flags;

	method.dynamicCall(returnType, 2 + paramTypes.length, callFlags, symbol.getName());

	}

	if (isOptimistic) {
	method.label(endTry);
	}

	method._return(returnType);

	if (isOptimistic) {
	// We caught a UnwarrantedOptimismException, replace 0 program point with actual program point
	method._catch(catchLabel);
	method.load(Type.INT, 2);
	method.invoke(REPLACE_PROGRAM_POINT);
	method.athrow();
	}

	method.end();
	}

	private String getStaticSignature() {
	if (staticSignature == null) {
	if (paramTypes == null) {
	staticSignature = Type.getMethodDescriptor(returnType, Type.typeFor(ScriptObject.class), Type.INT, Type.INT);
	} else {
	final Type[] params = new Type[paramTypes.length + FIXED_PARAM_COUNT];
	params[0] = Type.typeFor(ScriptObject.class);
	params[1] = Type.INT;
	params[2] = Type.INT;
	System.arraycopy(paramTypes, 0, params, FIXED_PARAM_COUNT, paramTypes.length);
	staticSignature = Type.getMethodDescriptor(returnType, params);
	}
	}
	return staticSignature;
	}

	@Override
	public String toString() {
	return methodName + " " + staticSignature;
	}

	}