[RegBankSelect] Print out the actual mapping of the operands.

This improves the debuggability of the pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272210 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/GlobalISel/RegBankSelect.cpp

@@ -502,6 +502,7 @@ void RegBankSelect::applyMapping(
     }
   }
   // Second, rewrite the instruction.
+  DEBUG(dbgs() << "Actual mapping of the operands: " << OpdMapper << '\n');
   RBI->applyMapping(OpdMapper);
 }