[llvm] [NVPTX] Vectorize loads when lowering of byval calls, misc. cleanup (PR #151070)

[Alex MacLean via llvm-commits]

================
@@ -150,8 +150,8 @@ define dso_local void @caller_St4x3(ptr nocapture noundef readonly byval(%struct
   ; CHECK:       )
----------------
AlexMaclean wrote:

This test seems to be checking for the defined function signature as well as some of the contents:
```
  ; CHECK-LABEL: .visible .func caller_St4x1(
  ; CHECK:               .param .align 4 .b8 caller_St4x1_param_0[4],
  ; CHECK:               .param .b64 caller_St4x1_param_1
  ; CHECK:       )
```
If we were to auto-generate the checks we'd miss this validation. Do you still think it makes sense to auto-generate? 

https://github.com/llvm/llvm-project/pull/151070