[llvm] Co-issue packed instructions by unpacking (PR #151704)

[Akash Dutta via llvm-commits]

akadutta wrote:

Corresponding change merged through https://github.com/llvm/llvm-project/pull/157968. That patch moves the optimization after post-RA scheduling. Closing this as this is an older iteration of 157968.

https://github.com/llvm/llvm-project/pull/151704