Aggregate returns possibly failing across JIT boundaries

Using in memory IR, I believe I'm seeing aggregate returns fail when either
a generated function calls an external function (not generated), which returns
an aggregate, or when an external non-generated function calls a generated
one which returns an aggregate. Is this a known issue?

Specifically when using a "non-generated" structure with two unsigned char, or two
unsigned fields, the second field is always set to zero on the retrieving side when
such an instance is returned by value to a generated calling function. The same
happens for a "generated" structure composed of two llvm::IntegerType::get(context, 8)
fields when returned to a non-generated function,. I have not used other aggregate
types or sizes, and am on OS X 64bit. When the appropriate functions, are on the
same side of JIT boundary (generated calling generated, and obviously non-generated
calling non-generated), the aggregate return works correctly.

If this is not a known issue, I will further elaborate with code later. As I switched to using
aggregate returning generated functions for generated callees, I have forward progress
on my current project albeit with some extra coding effort. :wink:

Also can someone point me to the source where such a two member structure is lowered
into two registers by the JIT when this structure is used in a return by value scenario?

Thanks in advance