Merge pull request #5250 from Leonardo2718/valhalla-acmp

Disable regDepCopyRemoval when value types are enabled

compiler/control/OMROptions.cpp

@@ -2315,6 +2315,24 @@ OMR::Options::jitLatePostProcess(TR::OptionSet *optionSet, void * jitConfig)
             fej9->waitOnCompiler(jitConfig);
             }
          }
+
+      // Disable regDepCopyRemoval when value types are enabled
+      //
+      // In OpenJ9, the implementation of value types does not behave well with
+      // regDepCopyRemoval. Specifically,  the ifacmp{eq,ne} operations rely on
+      // lowering that requires basic block splitting after GRA.
+      // RegDepCopyRemoval currently leaves the trees in a state that the post
+      // GRA block splitter cannot handle. So, for now, the optimization is
+      // disabled.
+      //
+      // https://github.com/eclipse/openj9/issues/9712 was opened to track the
+      // work to re-enable the optimization.
+      //
+      // Unfortunately, the design of the option processing framework requires
+      // the disabling code to be in OMR (rather than OpenJ9) and guarded
+      // with J9_PROJECT_SPECIFIC.
+      if (TR::Compiler->om.areValueTypesEnabled())
+         _disabledOptimizations[regDepCopyRemoval] = true;
 #endif
 
       }