/// Returns true if we proved that RCIdentity has a non-payloaded enum case,
/// false if RCIdentity has a payloaded enum case, and None if we failed to find
/// anything.
static llvm::Optional<bool> proveNonPayloadedEnumCase(SILBasicBlock *BB,
SILValue RCIdentity) {
// Then see if BB has one predecessor... if it does not, return None so we
// keep searching up the domtree.
SILBasicBlock *SinglePred = BB->getSinglePredecessorBlock();
if (!SinglePred)
return None;
// Check if SinglePred has a switch_enum terminator switching on
// RCIdentity... If it does not, return None so we keep searching up the
// domtree.
auto *SEI = dyn_cast<SwitchEnumInst>(SinglePred->getTerminator());
if (!SEI || SEI->getOperand() != RCIdentity)
return None;
// Then return true if along the edge from the SEI to BB, RCIdentity has a
// non-payloaded enum value.
NullablePtr<EnumElementDecl> Decl = SEI->getUniqueCaseForDestination(BB);
if (Decl.isNull())
return None;
return !Decl.get()->hasArgumentType();
}
