[llvm-branch-commits] [clang] [Clang] Default to async unwind tables for amdgcn (PR #166464)

[Scott Linder via llvm-branch-commits]

slinder1 wrote:

> > To avoid codegen changes when enabling debug-info
> 
> Don't really understand how this is connected to this; that's just a general bug. What does this actually do in the backend?
>
> What is the connection to the described backend problem?

It isn't directly connected, but from a user's perspective the behavior of `clang` is what really matters, and so the defaults here are important.

If a user is building without debug-info, hits a bug, turns on debug-info, and starts debugging they do not want codegen to change. Without this change in clang, they will observe codegen changes, because of the backend bug. With this change, they should not observe it, since they will have been generating CFI_INSTRUCTIONs already.

So in short this change is a workaround to hide the backend bug.

https://github.com/llvm/llvm-project/pull/166464