[llvm] [AMDGPU] ISel & PEI for whole wave functions (PR #145858)

[Matt Arsenault via llvm-commits]

================
@@ -2978,6 +2978,16 @@ void Verifier::visitFunction(const Function &F) {
           "perfect forwarding!",
           &F);
     break;
+  case CallingConv::AMDGPU_Gfx_WholeWave:
+    Check(F.arg_size() != 0 && F.arg_begin()->getType()->isIntegerTy(1),
----------------
arsenm wrote:

```suggestion
    Check(!F.arg_empty() && F.arg_begin()->getType()->isIntegerTy(1),
```

https://github.com/llvm/llvm-project/pull/145858