[Local] Add a convenient insertReplacementDbgValues overload, NFC

Add an overload for the common case where the replacement dbg.values
have the same DIExpressions as the originals.

llvm-svn: 335643
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 42828ea..13d96f5 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -267,13 +267,9 @@
       // The first cast (CSrc) is eliminable so we need to fix up or replace
       // the second cast (CI). CSrc will then have a good chance of being dead.
       auto *Res = CastInst::Create(NewOpc, CSrc->getOperand(0), CI.getType());
-
       // Replace debug users of the eliminable cast by emitting debug values
       // which refer to the new cast.
-      insertReplacementDbgValues(
-          *CSrc, *Res, *std::next(CI.getIterator()),
-          [](DbgInfoIntrinsic &OldDII) { return OldDII.getExpression(); });
-
+      insertReplacementDbgValues(*CSrc, *Res, *std::next(CI.getIterator()));
       return Res;
     }
   }