Switch some getAliasSet clients to MCRegAliasIterator.

MCRegAliasIterator can optionally visit the register itself, allowing
for simpler code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157837 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index aa10d1d..69bd1c2 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -187,10 +187,8 @@
         if (MO.isReg() && MO.isUse()) {
           unsigned Reg = MO.getReg();
           if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
-            LivePhysRegs.set(Reg);
-            for (const uint16_t *AliasSet = TRI->getAliasSet(Reg);
-                 *AliasSet; ++AliasSet)
-              LivePhysRegs.set(*AliasSet);
+            for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+              LivePhysRegs.set(*AI);
           }
         }
       }