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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "frontend/TDZCheckCache.h"

#include "frontend/BytecodeEmitter.h"

using namespace js;
using namespace js::frontend;

using mozilla::Maybe;
using mozilla::Nothing;
using mozilla::Some;

TDZCheckCache::TDZCheckCache(BytecodeEmitter* bce)
  : Nestable<TDZCheckCache>(&bce->innermostTDZCheckCache),
    cache_(bce->cx->frontendCollectionPool())
{}

bool
TDZCheckCache::ensureCache(BytecodeEmitter* bce)
{
    return cache_ || cache_.acquire(bce->cx);
}

Maybe<MaybeCheckTDZ>
TDZCheckCache::needsTDZCheck(BytecodeEmitter* bce, JSAtom* name)
{
    if (!ensureCache(bce))
        return Nothing();

    CheckTDZMap::AddPtr p = cache_->lookupForAdd(name);
    if (p)
        return Some(p->value().wrapped);

    MaybeCheckTDZ rv = CheckTDZ;
    for (TDZCheckCache* it = enclosing(); it; it = it->enclosing()) {
        if (it->cache_) {
            if (CheckTDZMap::Ptr p2 = it->cache_->lookup(name)) {
                rv = p2->value();
                break;
            }
        }
    }

    if (!cache_->add(p, name, rv)) {
        ReportOutOfMemory(bce->cx);
        return Nothing();
    }

    return Some(rv);
}

bool
TDZCheckCache::noteTDZCheck(BytecodeEmitter* bce, JSAtom* name,
                            MaybeCheckTDZ check)
{
    if (!ensureCache(bce))
        return false;

    CheckTDZMap::AddPtr p = cache_->lookupForAdd(name);
    if (p) {
        MOZ_ASSERT(!check, "TDZ only needs to be checked once per binding per basic block.");
        p->value() = check;
    } else {
        if (!cache_->add(p, name, check)) {
            ReportOutOfMemory(bce->cx);
            return false;
        }
    }

    return true;
}