[llvm-branch-commits] [Clang] Optionally use NewPM to run CodeGen Pipeline (PR #191579)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/191579

This patch adds a new -cc1 option to clang that runs the codegen
pipeline using the NewPM. This enables easy testing of this flow through
clang.