In each case I am using locally built VMs with the same code from git. My cloned repository (https://github.com/KenDickey/opensmalltalk-vm) was current with OpenSmalltalk's master as of a couple of weeks ago. I have not synched since then as I have a pull request open for my (proposed) changes to support aarch64 and am waiting for integration into the master to test.
The other test cases pass.
In each case a double result is properly returned (gdb) but I get lost in gcc3x_interp.c floatObjectOf() details.
I am time stressed at the moment, but gdb is showing that the proper values were calculated by the ffiTest prims.
Just after the test funs, in the FFIPlugin code (ARM64FFIPlugin.c) there is a code line
result1 = floatObjectOf(floatRet);
Just before this, gdb shows 'floatRet' as correct.