js/src/frontend/TDZCheckCache.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "frontend/TDZCheckCache.h"
   8
   9 #include "frontend/BytecodeEmitter.h"
  10
  11 using namespace js;
  12 using namespace js::frontend;
  13
  14 using mozilla::Maybe;
  15 using mozilla::Nothing;
  16 using mozilla::Some;
  17
  18 TDZCheckCache::TDZCheckCache(BytecodeEmitter* bce)
  19     : Nestable<TDZCheckCache>(&bce->innermostTDZCheckCache),
  20       cache_(bce->fc->nameCollectionPool()) {}
  21
  22 bool TDZCheckCache::ensureCache(BytecodeEmitter* bce) {
  23   return cache_ || cache_.acquire(bce->fc);
  24 }
  25
  26 Maybe<MaybeCheckTDZ> TDZCheckCache::needsTDZCheck(BytecodeEmitter* bce,
  27                                                   TaggedParserAtomIndex name) {
  28   if (!ensureCache(bce)) {
  29     return Nothing();
  30   }
  31
  32   CheckTDZMap::AddPtr p = cache_->lookupForAdd(name);
  33   if (p) {
  34     return Some(p->value().wrapped);
  35   }
  36
  37   MaybeCheckTDZ rv = CheckTDZ;
  38   for (TDZCheckCache* it = enclosing(); it; it = it->enclosing()) {
  39     if (it->cache_) {
  40       if (CheckTDZMap::Ptr p2 = it->cache_->lookup(name)) {
  41         rv = p2->value();
  42         break;
  43       }
  44     }
  45   }
  46
  47   if (!cache_->add(p, name, rv)) {
  48     ReportOutOfMemory(bce->fc);
  49     return Nothing();
  50   }
  51
  52   return Some(rv);
  53 }
  54
  55 bool TDZCheckCache::noteTDZCheck(BytecodeEmitter* bce,
  56                                  TaggedParserAtomIndex name,
  57                                  MaybeCheckTDZ check) {
  58   if (!ensureCache(bce)) {
  59     return false;
  60   }
  61
  62   CheckTDZMap::AddPtr p = cache_->lookupForAdd(name);
  63   if (p) {
  64     MOZ_ASSERT(
  65         !check,
  66         "TDZ only needs to be checked once per binding per basic block.");
  67     p->value() = check;
  68   } else {
  69     if (!cache_->add(p, name, check)) {
  70       ReportOutOfMemory(bce->fc);
  71       return false;
  72     }
  73   }
  74
  75   return true;
  76 }