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

[Ana Mihajlovic via llvm-commits]

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@@ -423,16 +419,13 @@ class AMDGPUInsertDelayAlu : public MachineFunctionPass {
         if (SII->isVALU(MI.getOpcode())) {
           for (const auto &Op : MI.defs()) {
             Register Reg = Op.getReg();
-            for (MCRegUnit Unit : TRI->regunits(Reg)) {
-              if (AMDGPU::isSGPR(Reg, TRI)) {
-                lastSGPRfromVALU = Unit;
-                break;
-              }
+            if (AMDGPU::isSGPR(Reg, TRI)) {
+              lastSGPRfromVALU = *(TRI->regunits(Reg).begin());
+              break;
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mihajlovicana wrote:

eliminating the outer loop by only taking the first unit of the SGPR operand

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