X-Git-Url: https://git.saurik.com/apple/javascriptcore.git/blobdiff_plain/b80e619319b1def83d1e8b4f84042b661be1be7f..81345200c95645a1b0d2635520f96ad55dfde63f:/runtime/JSString.cpp?ds=sidebyside diff --git a/runtime/JSString.cpp b/runtime/JSString.cpp index 6128790..10a16d9 100644 --- a/runtime/JSString.cpp +++ b/runtime/JSString.cpp @@ -24,203 +24,296 @@ #include "JSString.h" #include "JSGlobalObject.h" +#include "JSGlobalObjectFunctions.h" #include "JSObject.h" -#include "Operations.h" +#include "JSCInlines.h" #include "StringObject.h" #include "StringPrototype.h" +#include "StrongInlines.h" namespace JSC { -static const unsigned resolveRopeForSubstringCutoff = 4; +const ClassInfo JSString::s_info = { "string", 0, 0, 0, CREATE_METHOD_TABLE(JSString) }; -// Overview: this methods converts a JSString from holding a string in rope form -// down to a simple UString representation. It does so by building up the string -// backwards, since we want to avoid recursion, we expect that the tree structure -// representing the rope is likely imbalanced with more nodes down the left side -// (since appending to the string is likely more common) - and as such resolving -// in this fashion should minimize work queue size. (If we built the queue forwards -// we would likely have to place all of the constituent UStringImpls into the -// Vector before performing any concatenation, but by working backwards we likely -// only fill the queue with the number of substrings at any given level in a -// rope-of-ropes.) -void JSString::resolveRope(ExecState* exec) const +void JSRopeString::RopeBuilder::expand() { - ASSERT(isRope()); + ASSERT(m_index == JSRopeString::s_maxInternalRopeLength); + JSString* jsString = m_jsString; + RELEASE_ASSERT(jsString); + m_jsString = jsStringBuilder(&m_vm); + m_index = 0; + append(jsString); +} - // Allocate the buffer to hold the final string, position initially points to the end. - UChar* buffer; - if (PassRefPtr newImpl = UStringImpl::tryCreateUninitialized(m_length, buffer)) - m_value = newImpl; +void JSString::destroy(JSCell* cell) +{ + JSString* thisObject = static_cast(cell); + thisObject->JSString::~JSString(); +} + +void JSString::dumpToStream(const JSCell* cell, PrintStream& out) +{ + const JSString* thisObject = jsCast(cell); + out.printf("<%p, %s, [%u], ", thisObject, thisObject->className(), thisObject->length()); + if (thisObject->isRope()) + out.printf("[rope]"); else { - for (unsigned i = 0; i < m_fiberCount; ++i) { - RopeImpl::deref(m_other.m_fibers[i]); - m_other.m_fibers[i] = 0; + WTF::StringImpl* ourImpl = thisObject->m_value.impl(); + if (ourImpl->is8Bit()) + out.printf("[8 %p]", ourImpl->characters8()); + else + out.printf("[16 %p]", ourImpl->characters16()); + } + out.printf(">"); +} + +void JSString::visitChildren(JSCell* cell, SlotVisitor& visitor) +{ + JSString* thisObject = jsCast(cell); + Base::visitChildren(thisObject, visitor); + + if (thisObject->isRope()) + static_cast(thisObject)->visitFibers(visitor); + else { + StringImpl* impl = thisObject->m_value.impl(); + ASSERT(impl); + visitor.reportExtraMemoryUsage(thisObject, impl->costDuringGC()); + } +} + +void JSRopeString::visitFibers(SlotVisitor& visitor) +{ + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) + visitor.append(&m_fibers[i]); +} + +static const unsigned maxLengthForOnStackResolve = 2048; + +void JSRopeString::resolveRopeInternal8(LChar* buffer) const +{ + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) { + if (m_fibers[i]->isRope()) { + resolveRopeSlowCase8(buffer); + return; } - m_fiberCount = 0; - ASSERT(!isRope()); - ASSERT(m_value == UString()); - if (exec) - throwOutOfMemoryError(exec); - return; } - UChar* position = buffer + m_length; - - // Start with the current RopeImpl. - Vector workQueue; - RopeImpl::Fiber currentFiber; - for (unsigned i = 0; i < (m_fiberCount - 1); ++i) - workQueue.append(m_other.m_fibers[i]); - currentFiber = m_other.m_fibers[m_fiberCount - 1]; - while (true) { - if (RopeImpl::isRope(currentFiber)) { - RopeImpl* rope = static_cast(currentFiber); - // Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber' - // (we will be working backwards over the rope). - unsigned fiberCountMinusOne = rope->fiberCount() - 1; - for (unsigned i = 0; i < fiberCountMinusOne; ++i) - workQueue.append(rope->fibers()[i]); - currentFiber = rope->fibers()[fiberCountMinusOne]; - } else { - UStringImpl* string = static_cast(currentFiber); - unsigned length = string->length(); - position -= length; - UStringImpl::copyChars(position, string->characters(), length); - - // Was this the last item in the work queue? - if (workQueue.isEmpty()) { - // Create a string from the UChar buffer, clear the rope RefPtr. - ASSERT(buffer == position); - for (unsigned i = 0; i < m_fiberCount; ++i) { - RopeImpl::deref(m_other.m_fibers[i]); - m_other.m_fibers[i] = 0; - } - m_fiberCount = 0; - - ASSERT(!isRope()); - return; - } - - // No! - set the next item up to process. - currentFiber = workQueue.last(); - workQueue.removeLast(); + + LChar* position = buffer; + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) { + const StringImpl& fiberString = *m_fibers[i]->m_value.impl(); + unsigned length = fiberString.length(); + StringImpl::copyChars(position, fiberString.characters8(), length); + position += length; + } + ASSERT((buffer + m_length) == position); +} + +void JSRopeString::resolveRopeInternal16(UChar* buffer) const +{ + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) { + if (m_fibers[i]->isRope()) { + resolveRopeSlowCase(buffer); + return; } } + + UChar* position = buffer; + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) { + const StringImpl& fiberString = *m_fibers[i]->m_value.impl(); + unsigned length = fiberString.length(); + if (fiberString.is8Bit()) + StringImpl::copyChars(position, fiberString.characters8(), length); + else + StringImpl::copyChars(position, fiberString.characters16(), length); + position += length; + } + ASSERT((buffer + m_length) == position); } - -// This function construsts a substring out of a rope without flattening by reusing the existing fibers. -// This can reduce memory usage substantially. Since traversing ropes is slow the function will revert -// back to flattening if the rope turns out to be long. -JSString* JSString::substringFromRope(ExecState* exec, unsigned substringStart, unsigned substringLength) + +void JSRopeString::resolveRopeToAtomicString(ExecState* exec) const { - ASSERT(isRope()); + if (m_length > maxLengthForOnStackResolve) { + resolveRope(exec); + m_value = AtomicString(m_value); + return; + } - JSGlobalData* globalData = &exec->globalData(); + if (is8Bit()) { + LChar buffer[maxLengthForOnStackResolve]; + resolveRopeInternal8(buffer); + m_value = AtomicString(buffer, m_length); + } else { + UChar buffer[maxLengthForOnStackResolve]; + resolveRopeInternal16(buffer); + m_value = AtomicString(buffer, m_length); + } - UString substringFibers[3]; - - unsigned fiberCount = 0; - unsigned substringFiberCount = 0; - unsigned substringEnd = substringStart + substringLength; - unsigned fiberEnd = 0; - - RopeIterator end; - for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) { - ++fiberCount; - UStringImpl* fiberString = *it; - unsigned fiberStart = fiberEnd; - fiberEnd = fiberStart + fiberString->length(); - if (fiberEnd <= substringStart) - continue; - unsigned copyStart = std::max(substringStart, fiberStart); - unsigned copyEnd = std::min(substringEnd, fiberEnd); - if (copyStart == fiberStart && copyEnd == fiberEnd) - substringFibers[substringFiberCount++] = UString(fiberString); - else - substringFibers[substringFiberCount++] = UString(UStringImpl::create(fiberString, copyStart - fiberStart, copyEnd - copyStart)); - if (fiberEnd >= substringEnd) - break; - if (fiberCount > resolveRopeForSubstringCutoff || substringFiberCount >= 3) { - // This turned out to be a really inefficient rope. Just flatten it. - resolveRope(exec); - return jsSubstring(&exec->globalData(), m_value, substringStart, substringLength); + clearFibers(); + + // If we resolved a string that didn't previously exist, notify the heap that we've grown. + if (m_value.impl()->hasOneRef()) + Heap::heap(this)->reportExtraMemoryCost(m_value.impl()->cost()); +} + +void JSRopeString::clearFibers() const +{ + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) + m_fibers[i].clear(); +} + +AtomicStringImpl* JSRopeString::resolveRopeToExistingAtomicString(ExecState* exec) const +{ + if (m_length > maxLengthForOnStackResolve) { + resolveRope(exec); + if (AtomicStringImpl* existingAtomicString = AtomicString::find(m_value.impl())) { + m_value = *existingAtomicString; + clearFibers(); + return existingAtomicString; } + return nullptr; } - ASSERT(substringFiberCount && substringFiberCount <= 3); - if (substringLength == 1) { - ASSERT(substringFiberCount == 1); - UChar c = substringFibers[0].data()[0]; - if (c <= 0xFF) - return globalData->smallStrings.singleCharacterString(globalData, c); + if (is8Bit()) { + LChar buffer[maxLengthForOnStackResolve]; + resolveRopeInternal8(buffer); + if (AtomicStringImpl* existingAtomicString = AtomicString::find(buffer, m_length)) { + m_value = *existingAtomicString; + clearFibers(); + return existingAtomicString; + } + } else { + UChar buffer[maxLengthForOnStackResolve]; + resolveRopeInternal16(buffer); + if (AtomicStringImpl* existingAtomicString = AtomicString::find(buffer, m_length)) { + m_value = *existingAtomicString; + clearFibers(); + return existingAtomicString; + } } - if (substringFiberCount == 1) - return new (globalData) JSString(globalData, substringFibers[0]); - if (substringFiberCount == 2) - return new (globalData) JSString(globalData, substringFibers[0], substringFibers[1]); - return new (globalData) JSString(globalData, substringFibers[0], substringFibers[1], substringFibers[2]); + + return nullptr; } -JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UString& replacement) +void JSRopeString::resolveRope(ExecState* exec) const { - if (!isRope()) { - unsigned matchPosition = m_value.find(character); - if (matchPosition == UString::NotFound) - return JSValue(this); - return jsString(exec, m_value.substr(0, matchPosition), replacement, m_value.substr(matchPosition + 1)); + ASSERT(isRope()); + + if (is8Bit()) { + LChar* buffer; + if (RefPtr newImpl = StringImpl::tryCreateUninitialized(m_length, buffer)) { + Heap::heap(this)->reportExtraMemoryCost(newImpl->cost()); + m_value = newImpl.release(); + } else { + outOfMemory(exec); + return; + } + resolveRopeInternal8(buffer); + clearFibers(); + ASSERT(!isRope()); + return; } - RopeIterator end; + UChar* buffer; + if (RefPtr newImpl = StringImpl::tryCreateUninitialized(m_length, buffer)) { + Heap::heap(this)->reportExtraMemoryCost(newImpl->cost()); + m_value = newImpl.release(); + } else { + outOfMemory(exec); + return; + } + + resolveRopeInternal16(buffer); + clearFibers(); + ASSERT(!isRope()); +} + +// Overview: These functions convert a JSString from holding a string in rope form +// down to a simple String representation. It does so by building up the string +// backwards, since we want to avoid recursion, we expect that the tree structure +// representing the rope is likely imbalanced with more nodes down the left side +// (since appending to the string is likely more common) - and as such resolving +// in this fashion should minimize work queue size. (If we built the queue forwards +// we would likely have to place all of the constituent StringImpls into the +// Vector before performing any concatenation, but by working backwards we likely +// only fill the queue with the number of substrings at any given level in a +// rope-of-ropes.) +void JSRopeString::resolveRopeSlowCase8(LChar* buffer) const +{ + LChar* position = buffer + m_length; // We will be working backwards over the rope. + Vector workQueue; // Putting strings into a Vector is only OK because there are no GC points in this method. - // Count total fibers and find matching string. - size_t fiberCount = 0; - UStringImpl* matchString = 0; - int matchPosition = -1; - for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) { - ++fiberCount; - if (matchString) - continue; + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) + workQueue.append(m_fibers[i].get()); + + while (!workQueue.isEmpty()) { + JSString* currentFiber = workQueue.last(); + workQueue.removeLast(); - UStringImpl* string = *it; - matchPosition = string->find(character); - if (matchPosition == -1) + if (currentFiber->isRope()) { + JSRopeString* currentFiberAsRope = static_cast(currentFiber); + for (size_t i = 0; i < s_maxInternalRopeLength && currentFiberAsRope->m_fibers[i]; ++i) + workQueue.append(currentFiberAsRope->m_fibers[i].get()); continue; - matchString = string; + } + + StringImpl* string = static_cast(currentFiber->m_value.impl()); + unsigned length = string->length(); + position -= length; + StringImpl::copyChars(position, string->characters8(), length); } - if (!matchString) - return this; + ASSERT(buffer == position); +} - RopeBuilder builder(replacement.size() ? fiberCount + 2 : fiberCount + 1); - if (UNLIKELY(builder.isOutOfMemory())) - return throwOutOfMemoryError(exec); +void JSRopeString::resolveRopeSlowCase(UChar* buffer) const +{ + UChar* position = buffer + m_length; // We will be working backwards over the rope. + Vector workQueue; // These strings are kept alive by the parent rope, so using a Vector is OK. - for (RopeIterator it(m_other.m_fibers, m_fiberCount); it != end; ++it) { - UStringImpl* string = *it; - if (string != matchString) { - builder.append(UString(string)); + for (size_t i = 0; i < s_maxInternalRopeLength && m_fibers[i]; ++i) + workQueue.append(m_fibers[i].get()); + + while (!workQueue.isEmpty()) { + JSString* currentFiber = workQueue.last(); + workQueue.removeLast(); + + if (currentFiber->isRope()) { + JSRopeString* currentFiberAsRope = static_cast(currentFiber); + for (size_t i = 0; i < s_maxInternalRopeLength && currentFiberAsRope->m_fibers[i]; ++i) + workQueue.append(currentFiberAsRope->m_fibers[i].get()); continue; } - builder.append(UString(string).substr(0, matchPosition)); - if (replacement.size()) - builder.append(replacement); - builder.append(UString(string).substr(matchPosition + 1)); - matchString = 0; + StringImpl* string = static_cast(currentFiber->m_value.impl()); + unsigned length = string->length(); + position -= length; + if (string->is8Bit()) + StringImpl::copyChars(position, string->characters8(), length); + else + StringImpl::copyChars(position, string->characters16(), length); } - JSGlobalData* globalData = &exec->globalData(); - return JSValue(new (globalData) JSString(globalData, builder.release())); + ASSERT(buffer == position); } -JSString* JSString::getIndexSlowCase(ExecState* exec, unsigned i) +void JSRopeString::outOfMemory(ExecState* exec) const +{ + clearFibers(); + ASSERT(isRope()); + ASSERT(m_value.isNull()); + if (exec) + throwOutOfMemoryError(exec); +} + +JSString* JSRopeString::getIndexSlowCase(ExecState* exec, unsigned i) { ASSERT(isRope()); resolveRope(exec); // Return a safe no-value result, this should never be used, since the excetion will be thrown. if (exec->exception()) - return jsString(exec, ""); + return jsEmptyString(exec); ASSERT(!isRope()); - ASSERT(i < m_value.size()); + RELEASE_ASSERT(i < m_value.length()); return jsSingleCharacterSubstring(exec, m_value, i); } @@ -229,74 +322,52 @@ JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const return const_cast(this); } -bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result) +bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result) const { result = this; - number = value(exec).toDouble(); + number = jsToNumber(value(exec)); return false; } -bool JSString::toBoolean(ExecState*) const +bool JSString::toBoolean() const { return m_length; } double JSString::toNumber(ExecState* exec) const { - return value(exec).toDouble(); -} - -UString JSString::toString(ExecState* exec) const -{ - return value(exec); + return jsToNumber(value(exec)); } -inline StringObject* StringObject::create(ExecState* exec, JSString* string) +inline StringObject* StringObject::create(VM& vm, JSGlobalObject* globalObject, JSString* string) { - return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string); + StringObject* object = new (NotNull, allocateCell(vm.heap)) StringObject(vm, globalObject->stringObjectStructure()); + object->finishCreation(vm, string); + return object; } -JSObject* JSString::toObject(ExecState* exec) const +JSObject* JSString::toObject(ExecState* exec, JSGlobalObject* globalObject) const { - return StringObject::create(exec, const_cast(this)); + return StringObject::create(exec->vm(), globalObject, const_cast(this)); } -JSObject* JSString::toThisObject(ExecState* exec) const +JSValue JSString::toThis(JSCell* cell, ExecState* exec, ECMAMode ecmaMode) { - return StringObject::create(exec, const_cast(this)); + if (ecmaMode == StrictMode) + return cell; + return StringObject::create(exec->vm(), exec->lexicalGlobalObject(), jsCast(cell)); } -bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot) -{ - // The semantics here are really getPropertySlot, not getOwnPropertySlot. - // This function should only be called by JSValue::get. - if (getStringPropertySlot(exec, propertyName, slot)) - return true; - if (propertyName == exec->propertyNames().underscoreProto) { - slot.setValue(exec->lexicalGlobalObject()->stringPrototype()); - return true; - } - slot.setBase(this); - JSObject* object; - for (JSValue prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) { - object = asObject(prototype); - if (object->getOwnPropertySlot(exec, propertyName, slot)) - return true; - } - slot.setUndefined(); - return true; -} - -bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor) +bool JSString::getStringPropertyDescriptor(ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor) { if (propertyName == exec->propertyNames().length) { - descriptor.setDescriptor(jsNumber(exec, m_length), DontEnum | DontDelete | ReadOnly); + descriptor.setDescriptor(jsNumber(m_length), DontEnum | DontDelete | ReadOnly); return true; } - bool isStrictUInt32; - unsigned i = propertyName.toStrictUInt32(&isStrictUInt32); - if (isStrictUInt32 && i < m_length) { + unsigned i = propertyName.asIndex(); + if (i < m_length) { + ASSERT(i != PropertyName::NotAnIndex); // No need for an explicit check, the above test would always fail! descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly); return true; } @@ -304,23 +375,13 @@ bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& pr return false; } -bool JSString::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor) -{ - if (getStringPropertyDescriptor(exec, propertyName, descriptor)) - return true; - if (propertyName != exec->propertyNames().underscoreProto) - return false; - descriptor.setDescriptor(exec->lexicalGlobalObject()->stringPrototype(), DontEnum); - return true; -} - -bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot) +JSString* jsStringWithCacheSlowCase(VM& vm, StringImpl& stringImpl) { - // The semantics here are really getPropertySlot, not getOwnPropertySlot. - // This function should only be called by JSValue::get. - if (getStringPropertySlot(exec, propertyName, slot)) - return true; - return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot); + auto addResult = vm.stringCache.add(&stringImpl, nullptr); + if (addResult.isNewEntry) + addResult.iterator->value = jsString(&vm, String(stringImpl)); + vm.lastCachedString.set(vm, addResult.iterator->value.get()); + return addResult.iterator->value.get(); } } // namespace JSC