[llvm] [MachineCopyPropagation][NFC] Refactor EliminateSpillageCopies (PR #192609)

[Matt Arsenault via llvm-commits]

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@@ -421,20 +421,35 @@ class CopyTracker {
     if (!TRI.isSubRegisterEq(Dst, Reg))
       return nullptr;
 
-    for (const MachineInstr &MI :
-         make_range(static_cast<const MachineInstr *>(DefCopy)->getIterator(),
-                    Current.getIterator()))
-      for (const MachineOperand &MO : MI.operands())
-        if (MO.isRegMask())
-          if (MO.clobbersPhysReg(Dst)) {
-            LLVM_DEBUG(dbgs() << "MCP: Removed tracking of "
-                              << printReg(Dst, &TRI) << "\n");
-            return nullptr;
-          }
-
     return DefCopy;
   }
 
+  void clobberNonPreservedRegs(const BitVector &PreservedRegUnits,
+                               const TargetRegisterInfo &TRI,
+                               const TargetInstrInfo &TII, bool UseCopyInstr) {
+    SmallVector<MCRegUnit, 8> UnitsToClobber;
+    for (auto &[Unit, _] : Copies)
+      if (!PreservedRegUnits.test(static_cast<unsigned>(Unit)))
+        UnitsToClobber.push_back(Unit);
+
+    for (MCRegUnit Unit : UnitsToClobber) {
+      // If we clobber the RegUnit, it will mark all the DefReg Units
+      // as unavailable, which leads to issues if the Destination Reg Unit is
+      // preserved, and used later. As such, only mark them as unavailable if
+      // they are not preserved.
+      auto RegUnitInfo = Copies.find(Unit);
+      if (RegUnitInfo == Copies.end())
+        continue;
+
+      for (MCRegister DstReg : RegUnitInfo->second.DefRegs)
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arsenm wrote:

Braces 

https://github.com/llvm/llvm-project/pull/192609