debugger fails on Apple M1

[davecotter]

Environment:
Qt Creator IDE (v7.0.0), Xcode (13.4 (13F17a)), Mac M1 computer, building and debugging an INTEL app (not ARM), on Monterey OS (12.4), gobs of RAM, 64bit app (very large app with many dependencies, multimedia, boost etc)

symptom 1: the log file will stop showing output, even though the app keeps going
symptom 2: pressing pause button in debugger shows "interrupt requested" but the app is now hung and the debugger is hung
symptom 3: if you set a breakpoint instead, when you hit it, app hangs and debugger hangs
symptom 4: if you quit the app, debugger stays in stuck state, must pick "Abort Debuggnig" not once but twice for the app to be killed and the debugger to reset

happens intermittently. i can go for a few runs with no problems, then i have the problem every run, feels random.
rebooting computer doesn't help
using "separate debug info" or not does not affect problem

debugger log left.txt
debugger log right.txt

-davec

[llvmbot]

@llvm/issue-subscribers-lldb

[davecotter]

is someone looking at this quite critical issue?

[jasonmolenda]

I'm not clear what the logging is related to. Is this from using lldb as a VSCode plugin, or python scripts in the QT frameworks you're debugging? I don't recognize the format of any of it. If you're debugging with Xcode and the bundled lldb in there, and you're seeing an apparent hang/spin/delay, I would run sample lldb-rpc-server in a terminal window while it's happening, that can often give a good idea what is going on under the covers.

If this is an Xcode/bundled lldb debug scenario, I'd recommend filing a Feedback with Apple with the details -- I suspect the sample output may be helpful in narrowing down what type of issue it is.

[davecotter]

the logs are from using the Qt Creator IDE to do the debugging. I don't know the innards of Qt or how it handles things. But i know it uses xcode to complie, and lldb as the debugger, and the logs show lldb is definitely the crashing culprit.

here's a link to the original Qt forum post:
https://forum.qt.io/topic/135501/macos-hitting-breakpoint-hangs-m1-mac

and the Qt bug report where they decide the bug lies with lldb:
https://bugreports.qt.io/browse/QTCREATORBUG-27507

'run sample lldb-rpc-server'
I'm not handy with much command line stuff. do you mean, AFTER the symptoms start, run that? Or run it before they start, and wait for the symptoms? and... then what? I would not know what to report, i mostly use GUI tools and only do command line stuff when there's no GUI For it.

I suppose you'll need to get an M1 mac, and Qt Creator, and build an x64 app with it, and try to debug it, in order to reproduce the lldb crash

[jasonmolenda]

The problem here is that I can't tell where the problem lies -- in this Qt Creator IDE, lldb, or how it is using lldb. Someone who knows the Qt Creator IDE side of it is probably going to need to start diagnosing what is going on; if it lies on the lldb side of this system, and we can identify what Qt Creator is sending at the point where there's a hang, we could make better progress. If you were able to debug your app under Xcode, we could separate the Qt Creator IDE side of it, but that probably will not be straightforward; I imagine they have a well integrated system for building and debugging Qt apps all inside that IDE.

There may be people on this github who are more familiar with Qt Creator IDE than me, but given the information presented, I don't think this is the right place to start.