[llvm] r329287 - ARM: Do not spill CSR to stack on entry to noreturn functions

[Tim Northover via llvm-commits]

> Easy way to reproduce should be just attach Android device with debug enabled and run BUILDBOT_REVISION=329287 BUILDBOT_CLOBBER=zorg/zorg/buildbot/builders/sanitizers/buildbot_android.sh from some scratch dir.
Make sure to kill your adb server, because the script will download own one.

I'll give that a go, but it's late here and I won't get results today.

> Also we should revert the patch and investigate later.

I disagree with this; or at least I think anyone that reverts this
patch should commit to diagnosing the issue properly. We've massively
messed around the person who submitted this patch. He's been pinging
diligently for more than a month on both mailing list and IRC. And I
still think the chances are his patch is fundamentally sound, but has
unfortunate interactions with UBSan.

We've already let myeisha down; let's not compound that.

Cheers.

Tim.