[BACKEND] Update llvm to llvm/llvm-project@c08c6a71cfc5

[htyu]

Bumping llvm to include a loop unroller fix: https://github.com/llvm/llvm-project/pull/106164/files . This is needed for subsequent loop unroller upstreaming work.

[htyu]

It looks like the desired llvm package could not be found during the build. Is there anything I should do to get it generated?

[antiagainst]

Yes. You need to land a change in llvm-head to trigger building llvm at the desired commit first.

See #4601 for llvm-head and #4625 for main.

[htyu]

Bumping llvm to include a loop unroller fix: https://github.com/llvm/llvm-project/pull/106164/files . This is needed for subsequent loop unroller upstreaming work.

Thanks for the pointers! #4640 created.

[antiagainst]

Actually we identified a perf regression in AMD backend due to some LLVM commits brought in by #4537. Still investigating. There are already some LLVM integration landed after #4537. Would you mind to hold on landing this a bit if possible? Hopefully it won't take long to identify the issue at least.

[htyu]

Actually we identified a perf regression in AMD backend due to some LLVM commits brought in by #4537. Still investigating. There are already some LLVM integration landed after #4537. Would you mind to hold on landing this a bit if possible? Hopefully it won't take long to identify the issue at least.

Sounds good.

[antiagainst]

We've identified the issue caused by #4537 due to missing target machine we didn't run some passes now when optimizing llvm module. will have a fix up soon to unblock here.

[antiagainst]

#4655 addressed the regression due to llvm bump. Please feel free to proceed with this one!

[htyu]

#4655 addressed the regression due to llvm bump. Please feel free to proceed with this one!

Thanks for the update!