8330262: C2: simplify transfer of GC barrier data from Ideal to Mach nodes

Reviewed-by: eosterlund, kvn

Author: robcasloz

src/hotspot/share/opto/matcher.cpp

@@ -1890,11 +1890,7 @@ MachNode *Matcher::ReduceInst( State *s, int rule, Node *&mem ) {
   }
 
   // Have mach nodes inherit GC barrier data
-  if (leaf->is_LoadStore()) {
-    mach->set_barrier_data(leaf->as_LoadStore()->barrier_data());
-  } else if (leaf->is_Mem()) {
-    mach->set_barrier_data(leaf->as_Mem()->barrier_data());
-  }
+  mach->set_barrier_data(MemNode::barrier_data(leaf));
 
   return ex;
 }