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Bug 1117017 - Initialize the IdSet lazily in jsiter.cpp:Snapshot(). r=sfink.

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This commit is contained in:
Nicholas Nethercote
2015-01-07 13:47:10 -08:00
parent 778b4eee0c
commit 9e54e882a6
1 changed files with 16 additions and 9 deletions
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25
js/src/jsiter.cpp
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@@ -9,6 +9,7 @@
#include "jsiter.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Maybe.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/PodOperations.h"
@@ -45,6 +46,7 @@ using namespace js::gc;
using JS::ForOfIterator;
using mozilla::ArrayLength;
using mozilla::Maybe;
#ifdef JS_MORE_DETERMINISTIC
using mozilla::PodCopy;
#endif
@@ -96,7 +98,7 @@ NewKeyValuePair(JSContext *cx, jsid id, const Value &val, MutableHandleValue rva
static inline bool
Enumerate(JSContext *cx, HandleObject pobj, jsid id,
bool enumerable, unsigned flags, IdSet& ht, AutoIdVector *props)
bool enumerable, unsigned flags, Maybe<IdSet>& ht, AutoIdVector *props)
{
// We implement __proto__ using a property on |Object.prototype|, but
// because __proto__ is highly deserving of removal, we don't want it to
@@ -108,15 +110,22 @@ Enumerate(JSContext *cx, HandleObject pobj, jsid id,
return true;
if (!(flags & JSITER_OWNONLY) || pobj->is<ProxyObject>() || pobj->getOps()->enumerate) {
if (!ht) {
ht.emplace(cx);
// Most of the time there are only a handful of entries.
if (!ht->init(5))
return false;
}
// If we've already seen this, we definitely won't add it.
IdSet::AddPtr p = ht.lookupForAdd(id);
IdSet::AddPtr p = ht->lookupForAdd(id);
if (MOZ_UNLIKELY(!!p))
return true;
// It's not necessary to add properties to the hash table at the end of
// the prototype chain, but custom enumeration behaviors might return
// duplicated properties, so always add in such cases.
if ((pobj->is<ProxyObject>() || pobj->getProto() || pobj->getOps()->enumerate) && !ht.add(p, id))
if ((pobj->is<ProxyObject>() || pobj->getProto() || pobj->getOps()->enumerate) && !ht->add(p, id))
return false;
}
@@ -132,7 +141,7 @@ Enumerate(JSContext *cx, HandleObject pobj, jsid id,
}
static bool
EnumerateNativeProperties(JSContext *cx, HandleNativeObject pobj, unsigned flags, IdSet &ht,
EnumerateNativeProperties(JSContext *cx, HandleNativeObject pobj, unsigned flags, Maybe<IdSet> &ht,
AutoIdVector *props)
{
bool enumerateSymbols;
@@ -273,11 +282,9 @@ struct SortComparatorIds
static bool
Snapshot(JSContext *cx, HandleObject pobj_, unsigned flags, AutoIdVector *props)
{
// ~90% of the time this table ends up with 3 or fewer elements.
IdSet ht(cx);
if (!ht.init(3))
return false;
// We initialize |ht| lazily (in Enumerate()) because it ends up unused
// anywhere from 67--99.9% of the time.
Maybe<IdSet> ht;
RootedObject pobj(cx, pobj_);
do {