HLE Bios : Magic numbers, autobias, ReturnFromException...

[gameblabla]

So while investigating for the hang issues in Digimon Rumble Arena and Final Fantasy 8, i found this mysterious commented line of code

https://github.com/dmitrysmagin/pcsx4all/blob/master/src/psxbios.cpp#L1693

Commenting out this exact line allows Digimon Rumble Arena to go a bit further before it triggers the bios's exit function.
I asked Senquack about it and he has no idea, looking at nocash documentation does not give me any clues either.

This commit
4a18d9e#diff-58e9dc1093d659513f538cf2d0f50fc6
added a lot of stuff but the diffing did not work properly unfortunately...
Here's a diff between the initial import of PSX4ALL v2 and the commit followed after that touches psxbios.cpp
https://pastebin.com/crvN8wGU

Yeah there's a lot of stuff, including things not seen in other forks.
I later noticed that you removed autobias later
a7adf8b
followed by the magic numbers :
487a575

So hmm what was the purpose of autobias ? You said that it wasn't working properly but there's a few games requiring cycle accuracy for memory card functions afaik.
And what about the magic numbers ? How did you get them ? Reverse engineering ?