[llvm] [AMDGPU] Remove s_delay_alu for VALU->SGPR->SALU (PR #127212)

Tue Feb 25 09:00:22 PST 2025

================
@@ -377,6 +413,17 @@ class AMDGPUInsertDelayAlu : public MachineFunctionPass {
             }
           }
         }
+
+        if (SII->isVALU(MI.getOpcode())) {
+          for (const auto &Op : MI.defs()) {
+            Register Reg = Op.getReg();
+            if (AMDGPU::isSGPR(Reg, TRI)) {
+              lastSGPRfromVALU = *(TRI->regunits(Reg).begin());
----------------
mbrkusanin wrote:

```suggestion
              lastSGPRfromVALU = *MCRegUnitIterator(Reg, TRI);
```
The you can just construct the iterator which will figure out the first element. That way you avoid make_range + begin.


https://github.com/llvm/llvm-project/pull/127212
