[llvm] [AMDGPU] SIFixSgprCopies should not process twice VGPR to SGPR copies inserted by PHI preprocessing. (PR #134153)

[via llvm-commits]

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@@ -971,16 +971,29 @@ void SIFixSGPRCopies::analyzeVGPRToSGPRCopy(MachineInstr* MI) {
       }
     } else if (Inst->getNumExplicitDefs() != 0) {
       Register Reg = Inst->getOperand(0).getReg();
-      if (TRI->isSGPRReg(*MRI, Reg) && !TII->isVALU(*Inst))
-        for (auto &U : MRI->use_instructions(Reg))
-          Users.push_back(&U);
+      if (TRI->isSGPRReg(*MRI, Reg) && !TII->isVALU(*Inst)) {
+        if (Reg.isVirtual()) {
+          for (auto &U : MRI->use_instructions(Reg))
+            Users.push_back(&U);
+        } else {
+          auto I = Inst->getIterator();
+          auto E = Inst->getParent()->end();
+          while (++I != E) {
+            if (I->readsRegister(Reg, TRI))
+              Users.push_back(&*I);
+            if (I->modifiesRegister(Reg, TRI))
+              break;
+          }
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alex-t wrote:

Done

https://github.com/llvm/llvm-project/pull/134153