[llvm] [DWARF] Don't leak line numbers onto frame-setup instructions (PR #161845)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse approved this pull request.

LGTM; ideally the MIR would be generated with --simplify-mir.

I wonder whether the MIR is running the correct set of passes... we could start at a lower level where the push instructions exist and have framesetup flags. But on the other hand we cover the whole lowering-stack-changes-to-instructions process by having the test start this high, so the coverage is better. YMMV; I think it's probably fine as it is.

https://github.com/llvm/llvm-project/pull/161845