[llvm] [MachineScheduler] Fix physreg dependencies of ExitSU (PR #123541)

[Matt Arsenault via llvm-commits]

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@@ -209,13 +209,17 @@ void ScheduleDAGInstrs::addSchedBarrierDeps() {
   ExitSU.setInstr(ExitMI);
   // Add dependencies on the defs and uses of the instruction.
   if (ExitMI) {
+    const MCInstrDesc &MIDesc = ExitMI->getDesc();
     for (const MachineOperand &MO : ExitMI->all_uses()) {
+      unsigned OpIdx = MO.getOperandNo();
       Register Reg = MO.getReg();
       if (Reg.isPhysical()) {
+        bool IsRealUse = OpIdx < MIDesc.getNumOperands() ||
+                         MIDesc.hasImplicitUseOfPhysReg(Reg);
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arsenm wrote:

MIDesc.hasImplicitUseOfPhysReg also looks buggy to me. It doesn't have the MCRI argument like hasImplicitDefOfPhysReg, so it will miss any aliases 

https://github.com/llvm/llvm-project/pull/123541