[llvm] [AMDGPU] Add AMDGPU-specific module splitting (PR #89245)

[Anshil Gandhi via llvm-commits]

gandhi56 wrote:

I found a bug during the review of #89683. I will attach the test files here. These tests should pass when they are run individually and fail when they are tested as a group. These nondeterministic results show up when `AMDGPUSplitModule` or `SplitModule` are used for partitioning. I suspect it may have something to do with tie breaks during load balancing.

[clone-lds-function.ll.txt](https://github.com/llvm/llvm-project/files/15202789/clone-lds-function.ll.txt)
[clone-lds-function-ancestor-kernels.ll.txt](https://github.com/llvm/llvm-project/files/15202790/clone-lds-function-ancestor-kernels.ll.txt)
[clone-lds-function-successor.ll.txt](https://github.com/llvm/llvm-project/files/15202791/clone-lds-function-successor.ll.txt)


https://github.com/llvm/llvm-project/pull/89245