Switched ropes from malloc memory to GC memory
https://bugs.webkit.org/show_bug.cgi?id=70364
Reviewed by Gavin Barraclough.
~1% SunSpider speedup. Neutral elsewhere. Removes one cause for strings
having C++ destructors.
(JSC::visitChildren): Call the JSString visitChildren function now,
since it's no longer a no-op.
(JSC::JSString::~JSString): Moved this destructor out of line because
it's called virtually, so there's no value to inlining.
(JSC::JSString::RopeBuilder::expand): Switched RopeBuilder to be a thin
initializing wrapper around JSString. JSString now represents ropes
directly, rather than relying on an underlying malloc object.
(JSC::JSString::visitChildren): Visit our rope fibers, since they're GC
objects now.
(JSC::JSString::resolveRope):
(JSC::JSString::resolveRopeSlowCase):
(JSC::JSString::outOfMemory): Updated for operating on JSStrings instead
of malloc objects.
(JSC::JSString::replaceCharacter): Removed optimizations for substringing
ropes and replacing subsections of ropes. We want to reimplement versions
of these optimizations in the future, but this patch already has good
performance without them.
(JSC::RopeBuilder::JSString):
(JSC::RopeBuilder::finishCreation):
(JSC::RopeBuilder::createNull):
(JSC::RopeBuilder::create):
(JSC::RopeBuilder::createHasOtherOwner):
(JSC::jsSingleCharacterString):
(JSC::jsSingleCharacterSubstring):
(JSC::jsNontrivialString):
(JSC::jsString):
(JSC::jsSubstring):
(JSC::jsOwnedString): Lots of mechanical changes here. The two important
things are: (1) The fibers in JSString::m_fibers are JSStrings now, not
malloc objects; (2) I simplified the JSString constructor interface to
only accept PassRefPtr<StringImpl>, instead of variations on that like
UString, reducing refcount churn.
- runtime/JSValue.h:
- runtime/JSValue.cpp:
(JSC::JSValue::toPrimitiveString): Updated this function to return a
JSString instead of a UString, since that's what clients want now.
(JSC::jsAddSlowCase):
(JSC::jsString):
- runtime/SmallStrings.cpp:
(JSC::SmallStrings::createEmptyString): Updated for interface changes above.
- runtime/StringConstructor.cpp:
(JSC::constructWithStringConstructor):
(JSC::StringObject::create): Don't create a new JSString if we already
have a JSString.
- runtime/StringPrototype.cpp:
(JSC::stringProtoFuncConcat): Updated for interface changes above.
