gecko/js/src/jspropertycacheinlines.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla 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/MPL/
 *
 * 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 Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Mozilla Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Igor Bukanov <igor@mir2.org>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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 * ***** END LICENSE BLOCK ***** */

#ifndef jspropertycacheinlines_h___
#define jspropertycacheinlines_h___

#include "jspropertycache.h"
#include "jsscope.h"

using namespace js;

/* static */ inline bool
PropertyCache::matchShape(JSContext *cx, JSObject *obj, uint32 shape)
{
    return CX_OWNS_OBJECT_TITLE(cx, obj) && OBJ_SHAPE(obj) == shape;
}

/*
 * This method is designed to inline the fast path in js_Interpret, so it makes
 * "just-so" restrictions on parameters, e.g. pobj and obj should not be the
 * same variable, since for JOF_PROP-mode opcodes, obj must not be changed
 * because of a cache miss.
 *
 * On return, if atom is null then obj points to the scope chain element in
 * which the property was found, pobj is locked, and entry is valid. If atom is
 * non-null then no object is locked but entry is still set correctly for use,
 * e.g., by PropertyCache::fill and atom should be used as the id to find.
 *
 * We must lock pobj on a hit in order to close races with threads that might
 * be deleting a property from its scope, or otherwise invalidating property
 * caches (on all threads) by re-generating scope->shape.
 */
JS_ALWAYS_INLINE void
PropertyCache::test(JSContext *cx, jsbytecode *pc, JSObject *&obj,
                    JSObject *&pobj, PropertyCacheEntry *&entry, JSAtom *&atom)
{
    JS_ASSERT(this == &JS_PROPERTY_CACHE(cx));

    uint32 kshape = obj->map->shape;
    entry = &table[hash(pc, kshape)];
    PCMETER(pctestentry = entry);
    PCMETER(tests++);
    JS_ASSERT(&obj != &pobj);
    JS_ASSERT(entry->kshape < SHAPE_OVERFLOW_BIT);
    if (entry->kpc == pc && entry->kshape == kshape) {
        JSObject *tmp;
        pobj = obj;
        if (entry->vcapTag() == 1 &&
            (tmp = pobj->getProto()) != NULL) {
            pobj = tmp;
        }

        if (matchShape(cx, pobj, entry->vshape())) {
            PCMETER(pchits++);
            PCMETER(!entry->vcapTag() || protopchits++);
            atom = NULL;
            return;
        }
    }
    atom = fullTest(cx, pc, &obj, &pobj, entry);
    if (atom)
        PCMETER(misses++);
}

JS_ALWAYS_INLINE bool
PropertyCache::testForSet(JSContext *cx, jsbytecode *pc, JSObject *obj,
                          PropertyCacheEntry **entryp, JSObject **obj2p, JSAtom **atomp)
{
    uint32 shape = obj->map->shape;
    PropertyCacheEntry *entry = &table[hash(pc, shape)];
    *entryp = entry;
    PCMETER(pctestentry = entry);
    PCMETER(tests++);
    PCMETER(settests++);
    JS_ASSERT(entry->kshape < SHAPE_OVERFLOW_BIT);
    if (entry->kpc == pc && entry->kshape == shape && matchShape(cx, obj, shape))
        return true;

#ifdef DEBUG
    JSObject *orig = obj;
#endif
    JSAtom *atom = fullTest(cx, pc, &obj, obj2p, entry);
    if (atom) {
        PCMETER(misses++);
        PCMETER(setmisses++);
    } else {
        JS_ASSERT(obj == orig);
    }
    *atomp = atom;
    return false;
}

JS_ALWAYS_INLINE bool
PropertyCache::testForInit(JSRuntime *rt, jsbytecode *pc, JSObject *obj, JSScope *scope,
                           JSScopeProperty **spropp, PropertyCacheEntry **entryp)
{
    JS_ASSERT(scope->object == obj);
    JS_ASSERT(!scope->sealed());
    uint32 kshape = scope->shape;
    PropertyCacheEntry *entry = &table[hash(pc, kshape)];
    *entryp = entry;
    PCMETER(pctestentry = entry);
    PCMETER(tests++);
    PCMETER(initests++);
    JS_ASSERT(entry->kshape < SHAPE_OVERFLOW_BIT);

    if (entry->kpc == pc &&
        entry->kshape == kshape &&
        entry->vshape() == rt->protoHazardShape) {
        PCMETER(pchits++);
        PCMETER(inipchits++);
        JS_ASSERT(entry->vcapTag() == 0);
        *spropp = entry->vword.toSprop();
        JS_ASSERT((*spropp)->writable());
        return true;
    }
    return false;
}

#endif /* jspropertycacheinlines_h___ */