8204210: Implementation: JEP 333: ZGC: A Scalable Low-Latency Garbage Collector (Experimental)

Co-authored-by: Stefan Karlsson <stefan.karlsson@oracle.com>
Co-authored-by: Erik Osterlund <erik.osterlund@oracle.com>
Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Co-authored-by: Kim Barrett <kim.barrett@oracle.com>
Co-authored-by: Nils Eliasson <nils.eliasson@oracle.com>
Co-authored-by: Rickard Backman <rickard.backman@oracle.com>
Co-authored-by: Roland Westrelin <rwestrel@redhat.com>
Co-authored-by: Coleen Phillimore <coleen.phillimore@oracle.com>
Co-authored-by: Robbin Ehn <robbin.ehn@oracle.com>
Co-authored-by: Gerard Ziemski <gerard.ziemski@oracle.com>
Co-authored-by: Hugh Wilkinson <hugh.wilkinson@intel.com>
Co-authored-by: Sandhya Viswanathan <sandhya.viswanathan@intel.com>
Co-authored-by: Bill Wheeler <bill.npo.wheeler@intel.com>
Co-authored-by: Vinay K. Awasthi <vinay.k.awasthi@intel.com>
Co-authored-by: Yasumasa Suenaga <yasuenag@gmail.com>
Reviewed-by: pliden, stefank, eosterlund, ehelin, sjohanss, rbackman, coleenp, ihse, jgeorge, lmesnik, rkennke

src/hotspot/share/compiler/compilerDirectives.hpp

@@ -66,7 +66,8 @@ NOT_PRODUCT(cflags(TraceOptoOutput,     bool, TraceOptoOutput, TraceOptoOutput))
     cflags(VectorizeDebug,          uintx, 0, VectorizeDebug) \
     cflags(CloneMapDebug,           bool, false, CloneMapDebug) \
     cflags(IGVPrintLevel,           intx, PrintIdealGraphLevel, IGVPrintLevel) \
-    cflags(MaxNodeLimit,            intx, MaxNodeLimit, MaxNodeLimit)
+    cflags(MaxNodeLimit,            intx, MaxNodeLimit, MaxNodeLimit) \
+ZGC_ONLY(cflags(ZOptimizeLoadBarriers, bool, ZOptimizeLoadBarriers, ZOptimizeLoadBarriers))
 #else
   #define compilerdirectives_c2_flags(cflags)
 #endif