SILValue Lowering::emitIsa(SILGenFunction &SGF, SILLocation loc, Expr *operand, Type targetType, CheckedCastKind castKind) { // Handle collection downcasts separately. if (castKind == CheckedCastKind::ArrayDowncast || castKind == CheckedCastKind::DictionaryDowncast || castKind == CheckedCastKind::SetDowncast) { ManagedValue operandMV = SGF.emitRValueAsSingleValue(operand); ManagedValue optValue = emitCollectionDowncastExpr( SGF, operandMV, operand->getType(), loc, targetType, SGFContext(), /*conditional=*/true) .getAsSingleValue(SGF, loc); // Materialize the input. SILValue optValueTemp; if (optValue.getType().isAddress()) { optValueTemp = optValue.forward(SGF); } else { optValueTemp = SGF.emitTemporaryAllocation(loc, optValue.getType()); optValue.forwardInto(SGF, loc, optValueTemp); } return SGF.emitDoesOptionalHaveValue(loc, optValueTemp); } // Prepare a jump destination here. ExitableFullExpr scope(SGF, CleanupLocation::get(loc)); auto i1Ty = SILType::getBuiltinIntegerType(1, SGF.getASTContext()); SGF.emitCheckedCastBranch(loc, operand, targetType, SGFContext(), [&](ManagedValue value) { SILValue yes = SGF.B.createIntegerLiteral(loc, i1Ty, 1); SGF.Cleanups.emitBranchAndCleanups(scope.getExitDest(), loc, yes); }, [&] { SILValue no = SGF.B.createIntegerLiteral(loc, i1Ty, 0); SGF.Cleanups.emitBranchAndCleanups(scope.getExitDest(), loc, no); }); auto contBB = scope.exit(); auto isa = new (SGF.SGM.M) SILArgument(contBB, i1Ty); return isa; }