[clang] [LLVM] Add new attribute `optdebug` to optimize for debugging (PR #66632)

[Paul T Robinson via cfe-commits]

pogo59 wrote:

Are there interactions between `optdebug` and other attributes that should be enforced by the verifier? Like, can't be mixed with `optnone`?

https://github.com/llvm/llvm-project/pull/66632