[clang-tools-extra] [llvm] [clang] Add out-of-line-atomics support to GlobalISel (PR #74588)

[Thomas Preud'homme via cfe-commits]

RoboTux wrote:

> Not an expert on atomics, but why would we have a libcall for -O0 but not for O1 in the tests?

I looked at it for the u?(min|max) and it seemed to boil down to the atomic expand pass being run at -O1 and above.

https://github.com/llvm/llvm-project/pull/74588