RTIO exception parameters are broken

[sbourdeauducq]

Stuck at 0, e.g.
artiq.coredevice.runtime_exceptions.RTIOUnderflow: at 0 ps on channel 0, violation 0 ps

[sbourdeauducq]

The bug happens when exceptions that are raised with parameters by the runtime are caught by a try/finally construct in the compiled code. The finally block re-raises the exception through the runtime's exception_raise, which clears the parameters. Fixing this properly needs making the compiler aware of exception parameters - not clearing the parameters when the compiled code raises an exception is not enough, e.g.

try:
    ...
except SomeException:
    # This does need to clear the parameters
    # (and change the ID of the exception re-raised by finally) 
    raise SomeOtherException
finally:
    ...

This bug is manifesting itself all the time at the moment, as the whole kernel code is encapsulated in a try/finally construct to handle RTIO handovers.

[whitequark]

new-py2llvm does not exhibit this bug.

[sbourdeauducq]

Please close when new-py2llvm is usable with the rest of ARTIQ.

[whitequark]

Closing since new compiler was merged.