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;
}
