[llvm] Globalopt pass produces invalid debug info (PR #100654)

[via llvm-commits]

ykhatav wrote:

> Hi -- using a recent opt (built from [1ebfc81](https://github.com/llvm/llvm-project/commit/1ebfc81a91194c000ac70b4ea53891cc956aa6eb)) the test case already produces a #dbg_value with "poison" operand, which suggests this patch isn't having any effect. Perhaps it was recently fixed somewhere else?

Sorry for the confusion. The problem only reproduces with the --experimental-debuginfo-iterators=false switch. Looks like the new debug format does not cause this issue. I have updated the test to use this switch. I think we should still keep the code change for backward compatibility.

https://github.com/llvm/llvm-project/pull/100654