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

[Shilei Tian via llvm-commits]

================
@@ -374,15 +374,21 @@ bool AMDGPUCallLowering::lowerReturn(MachineIRBuilder &B, const Value *Val,
     return true;
   }
 
-  unsigned ReturnOpc =
-      IsShader ? AMDGPU::SI_RETURN_TO_EPILOG : AMDGPU::SI_RETURN;
+  const bool IsWholeWave = MFI->isWholeWaveFunction();
+  unsigned ReturnOpc = IsWholeWave ? AMDGPU::G_AMDGPU_WHOLE_WAVE_FUNC_RETURN
+                       : IsShader  ? AMDGPU::SI_RETURN_TO_EPILOG
+                                   : AMDGPU::SI_RETURN;
   auto Ret = B.buildInstrNoInsert(ReturnOpc);
 
   if (!FLI.CanLowerReturn)
     insertSRetStores(B, Val->getType(), VRegs, FLI.DemoteRegister);
   else if (!lowerReturnVal(B, Val, VRegs, Ret))
     return false;
 
+  if (IsWholeWave) {
+    addOriginalExecToReturn(B.getMF(), Ret);
+  }
----------------
shiltian wrote:

```suggestion
  if (IsWholeWave)
    addOriginalExecToReturn(B.getMF(), Ret);
```

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