While I hate to call "compiler codegen bug", at this point I suspect a
tool issue with gcc [Debian 10.2.1-6 2021-01-10].
I would like to try with an updated gcc and I probably need to craft a
small example which either teaches me how to avoid the problem or can
convince the compiler port/maintainers that there is a problem.
Single stepping in gdb (stepi) just shows that the floatRet.d is not
getting set to the result -- no code to do this.
As as aside, the AllWinner D1 works fine but is vvvvveeeeeeeerrrrrryyy
ssllllloooooowww. So building and debugging takes patience.
The great news is that both Cuis and Squeak images run fine (unless you
load compressed files, which yield CRC errors).
I do have some time tomorrow (Saturday; 2 July) in Pacific Time Zone,
but I am not sure how we might proceed to trouble-shoot the problem.
It would be good to talk with you in any case.