[clang] [clang][utils] Add auto mode to reduction script (PR #163282)

[Aiden Grossman via cfe-commits]

boomanaiden154 wrote:

> would need some blessed way to crash the compiler, e.g. #pragma clang __debug crash crashes the frontend, need to figure out how to crash the middle/backend

What do you think the easiest way to do this is? I'm wondering if we could add clang builtins that trigger verifier errors? Doing that for the middle end would be easy. I'm not sure it would be easy to codegen something that makes it through to the backend though. Introducing IR intrinsics that produce verifier failures is the cleanest I can think of but feels a bit heavyweight.

https://github.com/llvm/llvm-project/pull/163282