[mlir][Pass] Register a signal handler when generating crash reproducers.

[rriddle]

Summary

The current implementation uses CrashRecoveryContext, but this only supports recovering in a certain number of cases. This revision adds a signal handler to support even more situations.

This revision was able to properly generate a reproducer for a segfault in the Inliner, that the current recovery couldn't.

Depends On D78314

[mehdi_amini]

Can you clarify a bit in the description what kind of situation this allows to handle that weren't possible before?

Also it isn't clear to me why do we need a stack of RecoveryReproducerContext? (maybe you can describe this part in the code comments)

[rriddle]

Resolve comments

[rriddle]

In D78315#2005841, @mehdi_amini wrote:

Can you clarify a bit in the description what kind of situation this allows to handle that weren't possible before?

Added an example. This allowed for me to generate a reproducer during an Inliner segfault that I couldn't otherwise.

Also it isn't clear to me why do we need a stack of RecoveryReproducerContext? (maybe you can describe this part in the code comments)

There could be multiple pass managers running simultaneously, with different MLIRContexts. Unless we guarantee that there is only ever one context at the same time(something I would be against), we need a stack to handle this case. There is also another situation right now, caused by the lack of dynamic pass pipelines ;), where a pass manager could get run within another. Though regardless of when we fix the second problem, the first one will still exist.

[mehdi_amini]

In D78315#2008460, @rriddle wrote:

In D78315#2005841, @mehdi_amini wrote:

There could be multiple pass managers running simultaneously, with different MLIRContexts.

Make sense, but then I have another question (see inline)

mlir/lib/Pass/Pass.cpp

617

So this seems to enforce that we always delete the stack of RecoveryReproducerContext in the order in which they were created, how does it happen? If multiple threads from the application are running different PassManagers for example?

[rriddle]

Resolve comments

[rriddle]

mlir/lib/Pass/Pass.cpp

617

Ooops, fixed.

[rriddle]

Add missing signals include