[llvm] [AMDGPU][SDAG] Support source modifiers on select integer operands (PR #147325)

[Chris Jackson via llvm-commits]

chrisjbris wrote:

Although moving to target independent combine enabled a simpler solution and resulted in improvements in other tests, I'm not sure this was the best way of working around the problem with the ordering of the combines. I'm considering other options.

https://github.com/llvm/llvm-project/pull/147325