Coreanalyzer can't handle RTIO underflow exceptions raised by spi2 devices

[jonaskeller]

Bug Report

One-Line Summary

The coreanalyzer tool exits with an error when run after an RTIO underflow was caused by an SPIMaster device (module artiq.coredevice.spi2).

Issue Details

Steps to Reproduce

1. Run this experiment:

from artiq.experiment import *

class cause_underflow(EnvExperiment):
    '''cause an RTIO underflow'''
    def build(self):
        self.setattr_device("core")    
        self.setattr_device("spi0")

    @kernel
    def run(self):
        self.core.reset()
        at_mu(self.core.get_rtio_counter_mu())
        self.spi0.set_config_mu(0, 32, 24, 1)

Relevant device_db.py entry:

    "spi0": {
        "type": "local",
        "module": "artiq.coredevice.spi2",
        "class": "SPIMaster",
       "arguments": {"channel": 46}    
    }

2. Run artiq_coreanalyzer -w output.vcd

Actual (undesired) Behavior

Traceback (most recent call last):
  File "C:\Anaconda3\envs\artiq4.0\Scripts\artiq_coreanalyzer-script.py", line 9, in <module>
    sys.exit(main())
  File "C:\Anaconda3\envs\artiq4.0\lib\site-packages\artiq\frontend\artiq_coreanalyzer.py", line 57, in main
    decoded_dump)
  File "C:\Anaconda3\envs\artiq4.0\lib\site-packages\artiq\coredevice\comm_analyzer.py", line 543, in decoded_dump_to_vcd
    channel_handlers[message.channel].process_message(message)
  File "C:\Anaconda3\envs\artiq4.0\lib\site-packages\artiq\coredevice\comm_analyzer.py", line 363, in process_message
    data = message.data
AttributeError: 'ExceptionMessage' object has no attribute 'data'

Your System (omit irrelevant parts)

• Operating System: Windows 7 64bit
• ARTIQ version: 4.0 0+gitbf50dcf7

[sbourdeauducq]

Is that only spi2 devices, or all devices?

[jonaskeller]

If I cause the underflow using a TTLOut device, it doesn't occur. (TTLHandler.process_message doesn't try to access message.data like SPIMaster2Handler.process_message does)

PS: I'd guess that the required fix is to move this line into the if clause that follows it, but I don't know enough about the context to be certain.

[jordens]

Yes. Thanks for submitting and analyzing!