Hi Jason, Sorry for the late reply - your mail got caught in my spam filter, and I just realized about the build breakage now after you reverted the commits. Just to confirm:
I looked at the original change again, and I think I know what's going wrong here: Devirtualization fails, and `promise_type` stays `void`. Obviously, `CreateValueObjectFromAddress` cannot create an object of type `void` and fails. The previous version was robust against that scenario, but https://reviews.llvm.org/D132815 accidentally regressed this. If a program has all the expected debug info, devirtualization should never fail and `promise_type` never stays `void`. It seems something is wrong/unexpected with the debug info on Darwin. Devirtualization relies on being able to identify the function pointer of the `destroy` function and inspects that function. So the root cause seems to be the same as for the revert https://github.com/llvm/llvm-project/commit/2b2f2f66141d52dc0d3082ddd12805d36872a189: For some reason, the debugger cannot find debug info for the function pointed to by the `destroy` function. However, I still don't quite understand what's wrong with the debug info on Mac. Either way, the pretty printer should of course be robust against such unexpected debug info. I think a simple additional check should be enough to make this robust so we no longer crash: if (!promise_type.isVoid()) { // <---- additional check lldb::ValueObjectSP promise = CreateValueObjectFromAddress( "promise", frame_ptr_addr + 2 * ptr_size, exe_ctx, promise_type); Status error; lldb::ValueObjectSP promisePtr = promise->AddressOf(error); if (error.Success()) m_promise_ptr_sp = promisePtr->Clone(ConstString("promise")); } Meta question: I am a bit confused about https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/. I thought LLVM's buildbots were set up to send an email in case somebody breaks the build. Also, I made sure that all builds in https://lab.llvm.org/buildbot/#/builders stayed green after my commit. So what are the expectations around which CIs need to stay green after a commit? Do I need to setup anything such that green.lab.llvm.org also sends me an email if I break it? Cheers, Adrian On Thu, Nov 24, 2022 at 10:50 PM Jason Molenda <ja...@molenda.com> wrote: > Ah, little misstatement below. My first thought was that promise_type was > null, but when I stepped through here with a debugger, it was not. I > didn't know how to dig in to a CompilerType object but there was some > reason why this CreateValueObjectFromAddress failed to return an actual > ValueObject, and I assumed it's something to do with that CompilerType. > But I didn't dig in far enough to understand what the issue in the type was. > > > On Nov 24, 2022, at 1:20 PM, Jason Molenda <ja...@molenda.com> wrote: > > > > Hi Adrian, the green dragon Incremental CI bot has been failing the past > couple of days after the changes for the coroutines formatter, most > directly https://reviews.llvm.org/D132815 landed - > TestCoroutineHandle.py results in a segfault on Darwin systems (both on the > CI and on my mac desktop) consistently. > https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/ > > > > It's crashing in formatters::StdlibCoroutineHandleSyntheticFrontEnd > where you're doing > > > > ``` > > // Add the `promise` member. We intentionally add `promise` as a > pointer type > > // instead of a value type, and don't automatically dereference this > pointer. > > // We do so to avoid potential very deep recursion in case there is a > cycle in > > // formed between `std::coroutine_handle`s and their promises. > > lldb::ValueObjectSP promise = CreateValueObjectFromAddress( > > "promise", frame_ptr_addr + 2 * ptr_size, exe_ctx, promise_type); > > Status error; > > lldb::ValueObjectSP promisePtr = promise->AddressOf(error); > > ``` > > > > and the promise_type dose not have a CompilerType so promisePtr is > nullptr and we crash on the method call to AddressOf. I looked briefly, but > this isn't a part of lldb I know well and I'm not sure the nature of the > problem. > > > > It's a long weekend in the US, so if you have a suggestion for > addressing this that'd be great, or I can roll back the changes necessary > to get the bot clean later today and we can look at this next week. > > > > Thanks! > > >
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