[llvm] [BPF] Support for `DW_TAG_variant_part` in BTF generation (PR #155783)

[Michal R via llvm-commits]

vadorovsky wrote:

Oh, so in your case rustc didn't emit `undef` in the constant, interesting. In my case, the IR fragments defining constants look like:

https://github.com/vadorovsky/llvm-project/commit/413a98a961841510f813244f454a34ef6e9f116a#diff-f411e8cbe94fed63916ca9eebac7652eddbb2db4770934eb94c26632216cbc58R42

The difference in our codes that I added more constants for different variants and added `no_mangle` attribute.

I'm AFK ATM. Tomorrow I will try to produce a similar IR without `undef`, or just use your IR in the test. What Rust version did you use? I used the latest nightly from a week ago.

(The issue with Rust emitting `undef` in any case will still will need to be fixed, eventually, but good to know it doesn't necessarily block my PR 🙂 )


https://github.com/llvm/llvm-project/pull/155783