As Janni pointed out here
http://www.mikroe.com/forum/viewtopic.php?p=47602#47602, the way to go is assign to Result in pascal even when the function is written completely in Assembler, so that, should the way the compiler handles return values change over mikroPascal versions, the code will only have to be recompiled.
That's fine. It wastes (not so much) RAM and code, but it's good enough to me.
I'm writing this so that if someone happens to read this thread while searching the forum about the same topic, he/she will not think that no one replied
at all, which is often descouraging. Granted, no one
at mikroE replied
directly, but I got help from other users in a thread about a related topic, and they shared with me what they have learnt both by experimenting
and on the forum. My best thanks to Warren (a.k.a. xor) and Janni.