void StructureRareData::setObjectToStringValue(ExecState* exec, VM& vm, Structure* ownStructure, JSString* value, PropertySlot toStringTagSymbolSlot)
{
if (m_giveUpOnObjectToStringValueCache)
return;
ObjectPropertyConditionSet conditionSet;
if (toStringTagSymbolSlot.isValue()) {
// We don't handle the own property case of Symbol.toStringTag because we would never know if a new
// object transitioning to the same structure had the same value stored in Symbol.toStringTag.
// Additionally, this is a super unlikely case anyway.
if (!toStringTagSymbolSlot.isCacheable() || toStringTagSymbolSlot.slotBase()->structure(vm) == ownStructure)
return;
// This will not create a condition for the current structure but that is good because we know the Symbol.toStringTag
// is not on the ownStructure so we will transisition if one is added and this cache will no longer be used.
conditionSet = generateConditionsForPrototypePropertyHit(vm, this, exec, ownStructure, toStringTagSymbolSlot.slotBase(), vm.propertyNames->toStringTagSymbol.impl());
ASSERT(!conditionSet.isValid() || conditionSet.hasOneSlotBaseCondition());
} else if (toStringTagSymbolSlot.isUnset())
conditionSet = generateConditionsForPropertyMiss(vm, this, exec, ownStructure, vm.propertyNames->toStringTagSymbol.impl());
else
return;
if (!conditionSet.isValid()) {
m_giveUpOnObjectToStringValueCache = true;
return;
}
ObjectPropertyCondition equivCondition;
for (const ObjectPropertyCondition& condition : conditionSet) {
if (condition.condition().kind() == PropertyCondition::Presence) {
ASSERT(isValidOffset(condition.offset()));
condition.object()->structure(vm)->startWatchingPropertyForReplacements(vm, condition.offset());
equivCondition = condition.attemptToMakeEquivalenceWithoutBarrier();
// The equivalence condition won't be watchable if we have already seen a replacement.
if (!equivCondition.isWatchable()) {
m_giveUpOnObjectToStringValueCache = true;
return;
}
} else if (!condition.isWatchable()) {
m_giveUpOnObjectToStringValueCache = true;
return;
}
}
ASSERT(conditionSet.structuresEnsureValidity());
for (ObjectPropertyCondition condition : conditionSet) {
if (condition.condition().kind() == PropertyCondition::Presence) {
m_objectToStringAdaptiveInferredValueWatchpoint = std::make_unique<ObjectToStringAdaptiveInferredPropertyValueWatchpoint>(equivCondition, this);
m_objectToStringAdaptiveInferredValueWatchpoint->install();
} else
m_objectToStringAdaptiveWatchpointSet.add(condition, this)->install();
}
m_objectToStringValue.set(vm, this, value);
}
