/*
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1997-1999 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s):
 * Norris Boyd
 * Roger Lawrence
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU Public License (the "GPL"), in which case the
 * provisions of the GPL are applicable instead of those above.
 * If you wish to allow use of your version of this file only
 * under the terms of the GPL and not to allow others to use your
 * version of this file under the NPL, indicate your decision by
 * deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL.  If you do not delete
 * the provisions above, a recipient may use your version of this
 * file under either the NPL or the GPL.
 */



package org.mozilla.javascript.optimizer;

import org.mozilla.javascript.*;

class Optimizer
{

    static final int NoType = 0;
    static final int NumberType = 1;
    static final int AnyType = 3;

    // It is assumed that (NumberType | AnyType) == AnyType

    void optimize(ScriptOrFnNode scriptOrFn, int optLevel)
    {
        itsOptLevel = optLevel;
        //  run on one function at a time for now
        int functionCount = scriptOrFn.getFunctionCount();
        for (int i = 0; i != functionCount; ++i) {
            OptFunctionNode f = OptFunctionNode.get(scriptOrFn, i);
            optimizeFunction(f);
        }
    }

    private void optimizeFunction(OptFunctionNode theFunction)
    {
        if (theFunction.fnode.requiresActivation()) return;

        inDirectCallFunction = theFunction.isTargetOfDirectCall();
        this.theFunction = theFunction;

        ObjArray statementsArray = new ObjArray();
        buildStatementList_r(theFunction.fnode, statementsArray);
        Node[] theStatementNodes = new Node[statementsArray.size()];
        statementsArray.toArray(theStatementNodes);

        Block.runFlowAnalyzes(theFunction, theStatementNodes);

        if (!theFunction.fnode.requiresActivation()) {
            /*
             * Now that we know which local vars are in fact always
             * Numbers, we re-write the tree to take advantage of
             * that. Any arithmetic or assignment op involving just
             * Number typed vars is marked so that the codegen will
             * generate non-object code.
             */
            parameterUsedInNumberContext = false;
            for (int i = 0; i < theStatementNodes.length; i++) {
                rewriteForNumberVariables(theStatementNodes[i]);
            }
            theFunction.setParameterNumberContext(parameterUsedInNumberContext);
        }

    }


/*
        Each directCall parameter is passed as a pair of values - an object
        and a double. The value passed depends on the type of value available at
        the call site. If a double is available, the object in java/lang/Void.TYPE
        is passed as the object value, and if an object value is available, then
        0.0 is passed as the double value.

        The receiving routine always tests the object value before proceeding.
        If the parameter is being accessed in a 'Number Context' then the code
        sequence is :
        if ("parameter_objectValue" == java/lang/Void.TYPE)
            ...fine..., use the parameter_doubleValue
        else
            toNumber(parameter_objectValue)

        and if the parameter is being referenced in an Object context, the code is
        if ("parameter_objectValue" == java/lang/Void.TYPE)
            new Double(parameter_doubleValue)
        else
            ...fine..., use the parameter_objectValue

        If the receiving code never uses the doubleValue, it is converted on
        entry to a Double instead.
*/


/*
        We're referencing a node in a Number context (i.e. we'd prefer it
        was a double value). If the node is a parameter in a directCall
        function, mark it as being referenced in this context.
*/
    private void markDCPNumberContext(Node n)
    {
        if (inDirectCallFunction && n.getType() == Token.GETVAR) {
            int varIndex = theFunction.getVarIndex(n);
            if (theFunction.isParameter(varIndex)) {
                parameterUsedInNumberContext = true;
            }
        }
    }

    private boolean convertParameter(Node n)
    {
        if (inDirectCallFunction && n.getType() == Token.GETVAR) {
            int varIndex = theFunction.getVarIndex(n);
            if (theFunction.isParameter(varIndex)) {
                n.removeProp(Node.ISNUMBER_PROP);
                return true;
            }
        }
        return false;
    }

    private int rewriteForNumberVariables(Node n)
    {
        switch (n.getType()) {
            case Token.EXPR_VOID : {
                    Node child = n.getFirstChild();
                    int type = rewriteForNumberVariables(child);
                    if (type == NumberType)
                        n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                     return NoType;
                }
            case Token.NUMBER :
                n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                return NumberType;

            case Token.GETVAR :
                {
                    int varIndex = theFunction.getVarIndex(n);
                    if (inDirectCallFunction
                        && theFunction.isParameter(varIndex))
                    {
                        n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                        return NumberType;
                    }
                    else if (theFunction.isNumberVar(varIndex)) {
                        n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                        return NumberType;
                    }
                    return NoType;
                }

            case Token.INC :
            case Token.DEC : {
                    Node child = n.getFirstChild();     // will be a GETVAR or GETPROP
                    if (child.getType() == Token.GETVAR) {
                        int varIndex = theFunction.getVarIndex(child);
                        if (theFunction.isNumberVar(varIndex)) {
                            n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                            markDCPNumberContext(child);
                            return NumberType;
                        }
                        else
                            return NoType;
                    }
                    else
                        return NoType;
                }
            case Token.SETVAR : {
                    Node lChild = n.getFirstChild();
                    Node rChild = lChild.getNext();
                    int rType = rewriteForNumberVariables(rChild);
                    int varIndex = theFunction.getVarIndex(n);
                    if (inDirectCallFunction
                        && theFunction.isParameter(varIndex))
                    {
                        if (rType == NumberType) {
                            if (!convertParameter(rChild)) {
                                n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                                return NumberType;
                            }
                            markDCPNumberContext(rChild);
                            return NoType;
                        }
                        else
                            return rType;
                    }
                    else if (theFunction.isNumberVar(varIndex)) {
                        if (rType != NumberType) {
                            n.removeChild(rChild);
                            n.addChildToBack(
                                new Node(Token.TO_DOUBLE, rChild));
                        }
                        n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                        markDCPNumberContext(rChild);
                        return NumberType;
                    }
                    else {
                        if (rType == NumberType) {
                            if (!convertParameter(rChild)) {
                                n.removeChild(rChild);
                                n.addChildToBack(
                                    new Node(Token.TO_OBJECT, rChild));
                            }
                        }
                        return NoType;
                    }
                }
            case Token.LE :
            case Token.LT :
            case Token.GE :
            case Token.GT : {
                    Node lChild = n.getFirstChild();
                    Node rChild = lChild.getNext();
                    int lType = rewriteForNumberVariables(lChild);
                    int rType = rewriteForNumberVariables(rChild);
                    markDCPNumberContext(lChild);
                    markDCPNumberContext(rChild);

                    if (convertParameter(lChild)) {
                        if (convertParameter(rChild)) {
                            return NoType;
                        } else if (rType == NumberType) {
                            n.putIntProp(Node.ISNUMBER_PROP, Node.RIGHT);
                        }
                    }
                    else if (convertParameter(rChild)) {
                        if (lType == NumberType) {
                            n.putIntProp(Node.ISNUMBER_PROP, Node.LEFT);
                        }
                    }
                    else {
                        if (lType == NumberType) {
                            if (rType == NumberType) {
                                n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                            }
                            else {
                                n.putIntProp(Node.ISNUMBER_PROP, Node.LEFT);
                            }
                        }
                        else {
                            if (rType == NumberType) {
                                n.putIntProp(Node.ISNUMBER_PROP, Node.RIGHT);
                            }
                        }
                    }
                    // we actually build a boolean value
                    return NoType;
                }

            case Token.ADD : {
                    Node lChild = n.getFirstChild();
                    Node rChild = lChild.getNext();
                    int lType = rewriteForNumberVariables(lChild);
                    int rType = rewriteForNumberVariables(rChild);


                    if (convertParameter(lChild)) {
                        if (convertParameter(rChild)) {
                            return NoType;
                        }
                        else {
                            if (rType == NumberType) {
                                n.putIntProp(Node.ISNUMBER_PROP, Node.RIGHT);
                            }
                        }
                    }
                    else {
                        if (convertParameter(rChild)) {
                            if (lType == NumberType) {
                                n.putIntProp(Node.ISNUMBER_PROP, Node.LEFT);
                            }
                        }
                        else {
                            if (lType == NumberType) {
                                if (rType == NumberType) {
                                    n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                                    return NumberType;
                                }
                                else {
                                    n.putIntProp(Node.ISNUMBER_PROP, Node.LEFT);
                                }
                            }
                            else {
                                if (rType == NumberType) {
                                    n.putIntProp(Node.ISNUMBER_PROP,
                                                 Node.RIGHT);
                                }
                            }
                        }
                    }
                    return NoType;
                }

            case Token.BITXOR :
            case Token.BITOR :
            case Token.BITAND :
            case Token.RSH :
            case Token.LSH :
            case Token.SUB :
            case Token.MUL :
            case Token.DIV :
            case Token.MOD : {
                    Node lChild = n.getFirstChild();
                    Node rChild = lChild.getNext();
                    int lType = rewriteForNumberVariables(lChild);
                    int rType = rewriteForNumberVariables(rChild);
                    markDCPNumberContext(lChild);
                    markDCPNumberContext(rChild);
                    if (lType == NumberType) {
                        if (rType == NumberType) {
                            n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                            return NumberType;
                        }
                        else {
                            if (!convertParameter(rChild)) {
                                n.removeChild(rChild);
                                n.addChildToBack(
                                    new Node(Token.TO_DOUBLE, rChild));
                                n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                            }
                            return NumberType;
                        }
                    }
                    else {
                        if (rType == NumberType) {
                            if (!convertParameter(lChild)) {
                                n.removeChild(lChild);
                                n.addChildToFront(
                                    new Node(Token.TO_DOUBLE, lChild));
                                n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                            }
                            return NumberType;
                        }
                        else {
                            if (!convertParameter(lChild)) {
                                n.removeChild(lChild);
                                n.addChildToFront(
                                    new Node(Token.TO_DOUBLE, lChild));
                            }
                            if (!convertParameter(rChild)) {
                                n.removeChild(rChild);
                                n.addChildToBack(
                                    new Node(Token.TO_DOUBLE, rChild));
                            }
                            n.putIntProp(Node.ISNUMBER_PROP, Node.BOTH);
                            return NumberType;
                        }
                    }
                }
            case Token.SETELEM :
            case Token.SETELEM_OP : {
                    Node arrayBase = n.getFirstChild();
                    Node arrayIndex = arrayBase.getNext();
                    Node rValue = arrayIndex.getNext();
                    int baseType = rewriteForNumberVariables(arrayBase);
                    if (baseType == NumberType) {// can never happen ???
                        if (!convertParameter(arrayBase)) {
                            n.removeChild(arrayBase);
                            n.addChildToFront(
                                new Node(Token.TO_OBJECT, arrayBase));
                        }
                    }
                    int indexType = rewriteForNumberVariables(arrayIndex);
                    if (indexType == NumberType) {
                        // setting the ISNUMBER_PROP signals the codegen
                        // to use the OptRuntime.setObjectIndex that takes
                        // a double index
                        n.putIntProp(Node.ISNUMBER_PROP, Node.LEFT);
                        markDCPNumberContext(arrayIndex);
                    }
                    int rValueType = rewriteForNumberVariables(rValue);
                    if (rValueType == NumberType) {
                        if (!convertParameter(rValue)) {
                            n.removeChild(rValue);
                            n.addChildToBack(
                                new Node(Token.TO_OBJECT, rValue));
                        }
                    }
                    return NoType;
                }
            case Token.GETELEM : {
                    Node arrayBase = n.getFirstChild();
                    Node arrayIndex = arrayBase.getNext();
                    int baseType = rewriteForNumberVariables(arrayBase);
                    if (baseType == NumberType) {// can never happen ???
                        if (!convertParameter(arrayBase)) {
                            n.removeChild(arrayBase);
                            n.addChildToFront(
                                new Node(Token.TO_OBJECT, arrayBase));
                        }
                    }
                    int indexType = rewriteForNumberVariables(arrayIndex);
                    if (indexType == NumberType) {
                        if (!convertParameter(arrayIndex)) {
                            // setting the ISNUMBER_PROP signals the codegen
                            // to use the OptRuntime.getObjectIndex that takes
                            // a double index
                            n.putIntProp(Node.ISNUMBER_PROP, Node.RIGHT);
                        }
                    }
                    return NoType;
                }
            case Token.CALL :
                {
                    Node child = n.getFirstChild(); // the function node
                    if (child.getType() == Token.GETELEM) {
                        // Optimization of x[0]() is not supported
                        // so bypass GETELEM optimization that
                        // rewriteForNumberVariables would trigger
                        rewriteAsObjectChildren(child, child.getFirstChild());
                    } else {
                        rewriteForNumberVariables(child);
                    }
                    child = child.getNext(); // the first arg

                    OptFunctionNode target
                            = (OptFunctionNode)n.getProp(Node.DIRECTCALL_PROP);
                    if (target != null) {
/*
    we leave each child as a Number if it can be. The codegen will
    handle moving the pairs of parameters.
*/
                        while (child != null) {
                            int type = rewriteForNumberVariables(child);
                            if (type == NumberType) {
                                markDCPNumberContext(child);
                            }
                            child = child.getNext();
                        }
                    } else {
                        rewriteAsObjectChildren(n, child);
                    }
                    return NoType;
                }
            default : {
                    rewriteAsObjectChildren(n, n.getFirstChild());
                    return NoType;
                }
        }
    }

    private void rewriteAsObjectChildren(Node n, Node child)
    {
        // Force optimized children to be objects
        while (child != null) {
            Node nextChild = child.getNext();
            int type = rewriteForNumberVariables(child);
            if (type == NumberType) {
                if (!convertParameter(child)) {
                    n.removeChild(child);
                    Node nuChild = new Node(Token.TO_OBJECT, child);
                    if (nextChild == null)
                        n.addChildToBack(nuChild);
                    else
                        n.addChildBefore(nuChild, nextChild);
                }
            }
            child = nextChild;
        }
    }

    private static void buildStatementList_r(Node node, ObjArray statements)
    {
        int type = node.getType();
        if (type == Token.BLOCK
            || type == Token.LOCAL_BLOCK
            || type == Token.LOOP
            || type == Token.FUNCTION)
        {
            Node child = node.getFirstChild();
            while (child != null) {
                buildStatementList_r(child, statements);
                child = child.getNext();
            }
        } else {
            statements.add(node);
        }
    }

    private int itsOptLevel;
    private boolean inDirectCallFunction;
    OptFunctionNode theFunction;
    private boolean parameterUsedInNumberContext;
}
