[llvm] [NVPTX] Improve NVVMReflect Efficiency (PR #134416)

[Artem Belevich via llvm-commits]

Artem-B wrote:

I don't know why there's a difference in whether reflect gets to run or not while emitting unoptimized IR. 
Can you try adding `-disable-llvm-optzns` and see if that helps?

In the end it does not really matter much. We can adjust the test to verify that we see the intended reflect value in the generated IR.

https://github.com/llvm/llvm-project/pull/134416