kdelibs/kjs/bytecode/machine.cpp.in

/*
 *  Main VM dispatch loop and related routines for KJS/Frostbyte
 *  This file is part of the KDE libraries
 *  Copyright (C) 2008 Maksim Orlovich (maksim@kde.org)
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "completion.h"
#include "ExecState.h"
#include "value.h"

#include "nodes.h"
#include "opcodes.h"
#include "LocalStorage.h"
#include "bytecode/opargs.h"
#include "bytecode/machine.h"
#include "scriptfunction.h"
#include "internal.h" // for printInfo
#include "ustring.h"
#include "debugger.h"

#include <stdio.h>

// maximum global call stack size. Protects against accidental or
// malicious infinite recursions. Define to -1 if you want no limit.
#if PLATFORM(DARWIN)
// Given OS X stack sizes we run out of stack at about 350 levels.
// If we improve our stack usage, we can bump this number.
#define KJS_MAX_STACK 100
#else
#define KJS_MAX_STACK 1000 // ### set system specific
#endif

namespace KJS {

#if defined(__GNUC__)
#define USE_LABEL_VALS
#endif

// We can either do jumps via switch or a GCC extension
#ifdef USE_LABEL_VALS
    #define handler(X) l##X
#else
    #define handler(X) case OpByteCode_##X
#endif


// #define COUNT_INSTRS

// A little profiling aid -- counts the # of dynamic instances of each instruction.
#ifdef COUNT_INSTRS

static unsigned instrCounts[OpByteCode_NumValues];

struct InstrCountPrinter
{
    ~InstrCountPrinter() {
        for (int c = 0; c < OpByteCode_NumValues; ++c) {
            printf("%9d %s\n", instrCounts[c], OpByteCodeVals[c]);
        }
    }
};

static InstrCountPrinter dumpCounts;
#endif

// ### Need to consolidate this w/things remaining in nodes.cpp somehow.
static void substitute(UString &string, const UString &substring)
{
    int position = string.find("%s");
    assert(position != -1);
    UString newString = string.substr(0, position);
    newString.append(substring);
    newString.append(string.substr(position + 2));
    string = newString;
}

NEVER_INLINE void throwUndefinedVariableError(ExecState* exec, const Identifier& ident)
{
    UString msg = "Can't find variable: %s";
    substitute(msg, ident.ustring());
    throwError(exec, ReferenceError, msg);
}

static JSValue* typeStringForValue(JSValue* v)
{
    switch (v->type()) {
    case UndefinedType:
        return jsString("undefined");
    case NullType:
        return jsString("object");
    case BooleanType:
        return jsString("boolean");
    case NumberType:
        return jsString("number");
    case StringType:
        return jsString("string");
    default:
        if (v->isObject()) {
            // Return "undefined" for objects that should be treated
            // as null when doing comparisons.
            if (static_cast<JSObject*>(v)->masqueradeAsUndefined())
                return jsString("undefined");
            else if (static_cast<JSObject*>(v)->isFunctionType())
                return jsString("function");
        }

        return jsString("object");
    }
}

template<bool errorOut, bool trySkipOne, bool replaceActivations>
ALWAYS_INLINE void lookupScopeAndFetch(ExecState* exec, Identifier* varName, JSValue*& scopeOut, JSValue*& valOut)
{
    const ScopeChain& chain = exec->scopeChain();
    ScopeChainIterator iter = chain.begin();
    ScopeChainIterator end = chain.end();

    // we must always have something in the scope chain
    assert(iter != end);

    JSObject *scopeObj = *iter;
    if (trySkipOne && !scopeObj->isLocalInjected()) {
        // Unless eval introduced new variables dynamically,
        // we know this isn't in the top scope
        ++iter;
    }

    PropertySlot slot;
    do {
        scopeObj = *iter;
        ++iter;
        if (scopeObj->getPropertySlot(exec, *varName, slot)) {
            if (!replaceActivations) {
                scopeOut = scopeObj;
            } else {
                // Common case: we found it in global object -- no need to check
                // if it's an activation
                if (iter == end || !scopeObj->isActivation())
                    scopeOut = scopeObj;
                else
                    scopeOut = exec->dynamicInterpreter()->globalObject();
            }
            valOut   = slot.getValue(exec, scopeObj, *varName);
            return;
        }
    } while (iter != end);

    scopeOut = scopeObj;
    valOut = jsUndefined();
    if (errorOut) {
        throwUndefinedVariableError(exec, *varName);
    }
}

static int depth;

NEVER_INLINE JSValue* handleStackOverflow(ExecState* exec) {
    depth -= 11; //Give the debugger some room..
    JSValue *ret = throwError(exec, RangeError, "Maximum call stack size exceeded.");
    depth += 10; //Put it back..
    return ret;
}

enum Dir { Enter, Exit };

NEVER_INLINE void changeDebugContext(Dir d, ExecState* exec, Node* n) {
    FunctionBodyNode* body = static_cast<FunctionBodyNode*>(n);
    Debugger* dbg = exec->dynamicInterpreter()->debugger();
    List args;
    FunctionImp* fn = 0;

    // Find the activation that contains arguments, fn
    const ScopeChain& chain = exec->scopeChain();
    for (ScopeChainIterator iter = chain.begin(); iter != chain.end(); ++iter) {
        JSObject* scopeObj = *iter;

        if (scopeObj->isActivation()) {
            ActivationImp* act = static_cast<ActivationImp*>(scopeObj);
            args = act->passedInArguments();
            fn   = static_cast<FunctionImp*>(act->function());
            break;
        }
    }

    if (d == Enter)
        dbg->enterContext(exec, body->sourceId(), body->firstLine(), fn, args);
    else
        dbg->exitContext(exec, body->sourceId(), body->lastLine(), fn);
}

class ForInState: public JSObject {
public:
    PropertyNameArray* array;
    int                pos;

    ForInState() {
        array = new PropertyNameArray;
        pos   = 0;
    }
    
    ~ForInState() {
        delete array;
    }
};

struct DepthCleanup
{
    ~DepthCleanup() { --depth; }
};


ALWAYS_INLINE_INTO JSValue*
Machine::runBlock(ExecState* exec, const CodeBlock& codeBlock, ExecState* parentExec) {

#ifdef USE_LABEL_VALS
    // Jump table, if needed
    @generate
#endif

    ++depth;
    if (depth > KJS_MAX_STACK)
        return handleStackOverflow(exec);

    DepthCleanup dc;

    const unsigned char* base = codeBlock.data();
    const unsigned char* pc   = base;
    List workList;
    LocalStorageEntry* localStore = exec->localStorage();
    exec->setMachineRegisters(base, &pc, &localStore);
    JSObject* globalObject = exec->dynamicInterpreter()->globalObject();

    while (true) {
    begin:
#ifdef COUNT_INSTRS
        OpByteCode opCodeLog = *reinterpret_cast<const OpByteCode*>(pc);
        ++instrCounts[opCodeLog];
#endif
        @generate
    }
}

}

// kate: indent-width 4; replace-tabs on; tab-width 4; space-indent on; hl c++;