Ping

@ychen I've rebased and fixed some pre-merge build and formatting issues. Could you please have another look at this review? If it looks OK could I also ask you to commit it for me, please? It's my first submission and I don't have commit rights myself.
Regards,
Raoul

[CodeGen] Add extension points for TargetPassConfig::addMachinePasses

[CodeGen] Add extension points for TargetPassConfig::addMachinePasses

@ychen apologies for that, the base revision should now be efc013ec4d950a68e6f80dd98cda35e1a96a6fc8 from the main repo.

[CodeGen] Add extension points for TargetPassConfig::addMachinePasses

@ychen I've updated this review with your suggested changes. I've removed the extension filtering in TargetPassConfig, simplified the test and added an example. The example doesn't try to use the new pass manager because the last time I checked it still wasn't useful for machine passes. What do you think?

[CodeGen] Simplify unit test for TargetPassConfig::addExtension and
add example plugin module

In D98591#2627643, @ychen wrote:

Could you add an example like llvm/examples/Bye and a test using llc -load?

Thanks very much @ychen for looking at my review, and thanks for pointing me at the examples/Bye/Bye.cpp example code. I didn't know we could do that kind of thing in the build and I'll post an update with a new example later this week.

Hi this is my first submission to the LLVM project. I selected reviewers by looking at the recent commit history of TargetPassConfig.h so I hope I haven't gone too far wrong with that. Evan Cheng is listed in the CODE_OWNERS.txt for "parts of code generator not covered by someone else" but I couldn't find his user name on Phabricator (perhaps he doesn't have one).