MachineInstr: Print name for subreg index in SUBREG_TO_REG

SUBREG_TO_REG takes a subregister index as 3rd operand, print the name
instead of a number. We already do the same for INSERT_SUBREG and
REG_SEQUENCE.

llvm-svn: 291481
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index d2ce001..2f2e3b3 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -1840,7 +1840,8 @@
         OS << "!\"" << DIV->getName() << '\"';
       else
         MO.print(OS, MST, TRI);
-    } else if (TRI && (isInsertSubreg() || isRegSequence()) && MO.isImm()) {
+    } else if (TRI && (isInsertSubreg() || isRegSequence() ||
+                       (isSubregToReg() && i == 3)) && MO.isImm()) {
       OS << TRI->getSubRegIndexName(MO.getImm());
     } else if (i == AsmDescOp && MO.isImm()) {
       // Pretty print the inline asm operand descriptor.