[llvm] [AMDGPU] Avoid put implicit_def into bundle that break reg's liveness (PR #142563)

[via llvm-commits]

Shoreshen wrote:

> > I think we may not need to test arbitrary sequence of insts since we don't need to tests inst seq that cannot be bundled??
> 
> The whole point of unit testing is that you can test all the edge cases, not just the cases that currently occur in practice. I am suggesting we should do that for finalizeBundle. I'm just not sure exactly _how_ to do it.

Hi @jayfoad , this patch fix the following situation:
1. physical registers are separately defined inside the bundle, e.g. we define SGPR1 and SGPR2 in 2 different insts
2. their "super" register was used in side the bundle. e.g. we use SGPR1_SGPR2 in some inst

In this situation, we should regard the "super" as internal for the bundle instruction.

I'm not sure what should we try to test by using unit tests. Simply from the functionality, we can use MIR tests in my point of view...

Thanks

https://github.com/llvm/llvm-project/pull/142563