[llvm] [AMDGPU] Generate waterfall for calls with SGPR(inreg) argument (PR #146997)

[Juan Manuel Martinez Caamaño via llvm-commits]

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@@ -6827,7 +6824,7 @@ emitLoadScalarOpsFromVGPRLoop(const SIInstrInfo &TII,
 
   MachineBasicBlock::iterator I = LoopBB.begin();
   Register CondReg;
-
+  int Idx = 0;
   for (MachineOperand *ScalarOp : ScalarOps) {
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jmmartinez wrote:

Nitpick, but there is an `enumerate(Range)` helper. You can use it as:

```cpp
for (auto [Idx, ScalarOp] : enumerate(ScalarOps))
```

https://github.com/llvm/llvm-project/pull/146997