--- old/src/hotspot/cpu/aarch64/gc/shared/barrierSetAssembler_aarch64.hpp	2018-10-31 23:12:42.449730877 +0100
+++ new/src/hotspot/cpu/aarch64/gc/shared/barrierSetAssembler_aarch64.hpp	2018-10-31 23:12:42.281732437 +0100
@@ -73,7 +73,7 @@
   );
   virtual void barrier_stubs_init() {}
 
-  virtual bool needs_explicit_null_check(intptr_t offset);
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
 };
 
 #endif // CPU_AARCH64_GC_SHARED_BARRIERSETASSEMBLER_AARCH64_HPP
--- old/src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.hpp	2018-10-31 23:12:42.882726857 +0100
+++ new/src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.hpp	2018-10-31 23:12:42.722728342 +0100
@@ -73,7 +73,7 @@
     // Default implementation does not need to do anything.
   }
 
-  virtual bool needs_explicit_null_check(intptr_t offset);
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
 };
 
 #endif // CPU_ARM_GC_SHARED_BARRIERSETASSEMBLER_ARM_HPP
--- old/src/hotspot/cpu/ppc/gc/shared/barrierSetAssembler_ppc.hpp	2018-10-31 23:12:43.313722855 +0100
+++ new/src/hotspot/cpu/ppc/gc/shared/barrierSetAssembler_ppc.hpp	2018-10-31 23:12:43.160724275 +0100
@@ -51,7 +51,7 @@
 
   virtual void barrier_stubs_init() {}
 
-  virtual bool needs_explicit_null_check(intptr_t offset);
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
 };
 
 #endif // CPU_PPC_GC_SHARED_BARRIERSETASSEMBLER_PPC_HPP
--- old/src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.hpp	2018-10-31 23:12:43.740718890 +0100
+++ new/src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.hpp	2018-10-31 23:12:43.584720338 +0100
@@ -48,7 +48,7 @@
 
   virtual void barrier_stubs_init() {}
 
-  virtual bool needs_explicit_null_check(intptr_t offset);
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
 };
 
 #endif // CPU_S390_GC_SHARED_BARRIERSETASSEMBLER_S390_HPP
--- old/src/hotspot/cpu/sparc/gc/shared/barrierSetAssembler_sparc.hpp	2018-10-31 23:12:44.177714832 +0100
+++ new/src/hotspot/cpu/sparc/gc/shared/barrierSetAssembler_sparc.hpp	2018-10-31 23:12:44.016716327 +0100
@@ -50,7 +50,7 @@
 
   virtual void barrier_stubs_init() {}
 
-  virtual bool needs_explicit_null_check(intptr_t offset);
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
 };
 
 #endif // CPU_SPARC_GC_SHARED_BARRIERSETASSEMBLER_SPARC_HPP
--- old/src/hotspot/cpu/x86/gc/shared/barrierSetAssembler_x86.hpp	2018-10-31 23:12:44.603710876 +0100
+++ new/src/hotspot/cpu/x86/gc/shared/barrierSetAssembler_x86.hpp	2018-10-31 23:12:44.444712353 +0100
@@ -86,7 +86,7 @@
 
   virtual void nmethod_entry_barrier(MacroAssembler* masm);
 
-  virtual bool needs_explicit_null_check(intptr_t offset);
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
 };
 
 #endif // CPU_X86_GC_SHARED_BARRIERSETASSEMBLER_X86_HPP
--- old/src/hotspot/cpu/zero/gc/shared/barrierSetAssembler_zero.hpp	2018-10-31 23:12:45.059706642 +0100
+++ new/src/hotspot/cpu/zero/gc/shared/barrierSetAssembler_zero.hpp	2018-10-31 23:12:44.904708082 +0100
@@ -25,6 +25,11 @@
 #ifndef CPU_ZERO_GC_SHARED_BARRIERSETASSEMBLER_ZERO_HPP
 #define CPU_ZERO_GC_SHARED_BARRIERSETASSEMBLER_ZERO_HPP
 
-class BarrierSetAssembler;
+#include "memory/allocation.hpp"
+
+class BarrierSetAssembler : public CHeapObj<mtGC> {
+public:
+  virtual bool needs_explicit_null_check(intptr_t offset) const;
+};
 
 #endif // CPU_ZERO_GC_SHARED_BARRIERSETASSEMBLER_ZERO_HPP
--- old/src/hotspot/share/asm/assembler.cpp	2018-10-31 23:12:45.505702501 +0100
+++ new/src/hotspot/share/asm/assembler.cpp	2018-10-31 23:12:45.344703996 +0100
@@ -26,6 +26,7 @@
 #include "asm/codeBuffer.hpp"
 #include "asm/macroAssembler.hpp"
 #include "asm/macroAssembler.inline.hpp"
+#include "gc/shared/barrierSetAssembler.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/icache.hpp"
 #include "runtime/os.hpp"
--- old/src/hotspot/share/gc/shared/barrierSetAssembler.cpp	2018-10-31 23:12:45.942698444 +0100
+++ new/src/hotspot/share/gc/shared/barrierSetAssembler.cpp	2018-10-31 23:12:45.789699864 +0100
@@ -26,7 +26,7 @@
 #include "memory/universe.hpp"
 #include "utilities/globalDefinitions.hpp"
 
-bool BarrierSetAssembler::needs_explicit_null_check(intptr_t offset) {
+bool BarrierSetAssembler::needs_explicit_null_check(intptr_t offset) const {
   // Exception handler checks the nmethod's implicit null checks table
   // only when this method returns false.
 #ifdef _LP64