--- old/make/autoconf/hotspot.m4	2020-01-17 17:14:11.751117164 +0100
+++ new/make/autoconf/hotspot.m4	2020-01-17 17:14:11.649117169 +0100
@@ -25,7 +25,7 @@
 
 # All valid JVM features, regardless of platform
 VALID_JVM_FEATURES="compiler1 compiler2 zero minimal dtrace jvmti jvmci \
-    graal vm-structs jni-check services management cmsgc epsilongc g1gc parallelgc serialgc zgc nmt cds \
+    graal vm-structs jni-check services management cmsgc epsilongc g1gc parallelgc serialgc shenandoahgc zgc nmt cds \
     static-build link-time-opt aot jfr"
 
 # Deprecated JVM features (these are ignored, but with a warning)
@@ -338,6 +338,15 @@
     fi
   fi
 
+  # Only enable Shenandoah on supported arches
+  AC_MSG_CHECKING([if shenandoah can be built])
+  if test "x$OPENJDK_TARGET_CPU_ARCH" = "xx86" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
+    AC_MSG_RESULT([yes])
+  else
+    DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES shenandoahgc"
+    AC_MSG_RESULT([no, platform not supported])
+  fi
+
   # Only enable ZGC on supported platforms
   AC_MSG_CHECKING([if zgc can be built])
   if test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xx86_64"; then
@@ -349,7 +358,7 @@
 
   # Disable unsupported GCs for Zero
   if HOTSPOT_CHECK_JVM_VARIANT(zero); then
-    DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES epsilongc g1gc zgc"
+    DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES epsilongc g1gc shenandoahgc zgc"
   fi
 
   # Turn on additional features based on other parts of configure
@@ -483,7 +492,7 @@
   fi
 
   # All variants but minimal (and custom) get these features
-  NON_MINIMAL_FEATURES="$NON_MINIMAL_FEATURES cmsgc g1gc parallelgc serialgc epsilongc jni-check jvmti management nmt services vm-structs zgc"
+  NON_MINIMAL_FEATURES="$NON_MINIMAL_FEATURES cmsgc g1gc parallelgc serialgc epsilongc shenandoahgc jni-check jvmti management nmt services vm-structs zgc"
 
   AC_MSG_CHECKING([if cds should be enabled])
   if test "x$ENABLE_CDS" = "xtrue"; then
--- old/make/hotspot/gensrc/GensrcAdlc.gmk	2020-01-17 17:14:12.342117131 +0100
+++ new/make/hotspot/gensrc/GensrcAdlc.gmk	2020-01-17 17:14:12.240117137 +0100
@@ -136,6 +136,12 @@
       $d/os_cpu/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH)/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH).ad \
     )))
 
+  ifeq ($(call check-jvm-feature, shenandoahgc), true)
+    AD_SRC_FILES += $(call uniq, $(wildcard $(foreach d, $(AD_SRC_ROOTS), \
+        $d/cpu/$(HOTSPOT_TARGET_CPU_ARCH)/gc/shenandoah/shenandoah_$(HOTSPOT_TARGET_CPU).ad \
+      )))
+  endif
+
   SINGLE_AD_SRCFILE := $(ADLC_SUPPORT_DIR)/all-ad-src.ad
 
   INSERT_FILENAME_AWK_SCRIPT := \
--- old/make/hotspot/lib/JvmFeatures.gmk	2020-01-17 17:14:12.933117098 +0100
+++ new/make/hotspot/lib/JvmFeatures.gmk	2020-01-17 17:14:12.830117104 +0100
@@ -166,6 +166,11 @@
   JVM_EXCLUDE_PATTERNS += gc/z
 endif
 
+ifneq ($(call check-jvm-feature, shenandoahgc), true)
+  JVM_CFLAGS_FEATURES += -DINCLUDE_SHENANDOAHGC=0
+  JVM_EXCLUDE_PATTERNS += gc/shenandoah
+endif
+
 ifneq ($(call check-jvm-feature, jfr), true)
   JVM_CFLAGS_FEATURES += -DINCLUDE_JFR=0
   JVM_EXCLUDE_PATTERNS += jfr
--- old/make/hotspot/lib/JvmOverrideFiles.gmk	2020-01-17 17:14:13.511117067 +0100
+++ new/make/hotspot/lib/JvmOverrideFiles.gmk	2020-01-17 17:14:13.410117072 +0100
@@ -36,6 +36,11 @@
   BUILD_LIBJVM_assembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
   BUILD_LIBJVM_cardTableBarrierSetAssembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
   BUILD_LIBJVM_interp_masm_x86.cpp_CXXFLAGS := -Wno-uninitialized
+  ifeq ($(DEBUG_LEVEL), release)
+    # Need extra inlining to collapse all marking code into the hot marking loop
+    BUILD_LIBJVM_shenandoahConcurrentMark.cpp_CXXFLAGS := --param inline-unit-growth=1000
+    BUILD_LIBJVM_shenandoahTraversalGC.cpp_CXXFLAGS := --param inline-unit-growth=1000
+  endif
 endif
 
 LIBJVM_FDLIBM_COPY_OPT_FLAG := $(CXX_O_FLAG_NONE)
--- old/src/hotspot/cpu/aarch64/aarch64.ad	2020-01-17 17:14:14.086117035 +0100
+++ new/src/hotspot/cpu/aarch64/aarch64.ad	2020-01-17 17:14:13.983117041 +0100
@@ -1280,6 +1280,10 @@
     case Op_GetAndSetN:
     case Op_GetAndAddI:
     case Op_GetAndAddL:
+#if INCLUDE_SHENANDOAHGC
+    case Op_ShenandoahCompareAndSwapP:
+    case Op_ShenandoahCompareAndSwapN:
+#endif
       return true;
     case Op_CompareAndExchangeI:
     case Op_CompareAndExchangeN:
--- old/src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp	2020-01-17 17:14:14.814116995 +0100
+++ new/src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp	2020-01-17 17:14:14.712117000 +0100
@@ -36,6 +36,7 @@
 #include "gc/shared/c1/barrierSetC1.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "runtime/stubRoutines.hpp"
+#include "utilities/macros.hpp"
 #include "vmreg_x86.inline.hpp"
 
 #ifdef ASSERT
@@ -674,6 +675,11 @@
   if (type == T_OBJECT || type == T_ARRAY) {
     cmp_value.load_item_force(FrameMap::rax_oop_opr);
     new_value.load_item();
+#if INCLUDE_SHENANDOAHGC
+    if (UseShenandoahGC) {
+      __ cas_obj(addr->as_address_ptr()->base(), cmp_value.result(), new_value.result(), new_register(T_OBJECT), new_register(T_OBJECT));
+    } else
+#endif
     __ cas_obj(addr->as_address_ptr()->base(), cmp_value.result(), new_value.result(), ill, ill);
   } else if (type == T_INT) {
     cmp_value.load_item_force(FrameMap::rax_opr);
@@ -699,6 +705,12 @@
   // Because we want a 2-arg form of xchg and xadd
   __ move(value.result(), result);
   assert(type == T_INT || is_oop LP64_ONLY( || type == T_LONG ), "unexpected type");
+#if INCLUDE_SHENANDOAHGC
+  if (UseShenandoahGC) {
+    LIR_Opr tmp = is_oop ? new_register(type) : LIR_OprFact::illegalOpr;
+    __ xchg(addr, result, result, tmp);
+  } else
+#endif
   __ xchg(addr, result, result, LIR_OprFact::illegalOpr);
   return result;
 }
--- old/src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp	2020-01-17 17:14:15.410116962 +0100
+++ new/src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp	2020-01-17 17:14:15.308116968 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,7 @@
 #include "code/nativeInst.hpp"
 #include "code/vtableStubs.hpp"
 #include "gc/shared/gcLocker.hpp"
+#include "gc/shared/collectedHeap.hpp"
 #include "interpreter/interpreter.hpp"
 #include "logging/log.hpp"
 #include "memory/resourceArea.hpp"
@@ -1434,6 +1435,102 @@
   }
 }
 
+// Pin incoming array argument of java critical method
+static void pin_critical_native_array(MacroAssembler* masm,
+                                      VMRegPair reg,
+                                      int& pinned_slot) {
+  assert(UseShenandoahGC, "only supported in Shenandoah for now");
+  __ block_comment("pin_critical_native_array {");
+  Register tmp_reg = rax;
+
+  Label is_null;
+  VMRegPair tmp;
+  VMRegPair in_reg = reg;
+  bool on_stack = false;
+
+  tmp.set_ptr(tmp_reg->as_VMReg());
+  if (reg.first()->is_stack()) {
+    // Load the arg up from the stack
+    move_ptr(masm, reg, tmp);
+    reg = tmp;
+    on_stack = true;
+  } else {
+    __ movptr(rax, reg.first()->as_Register());
+  }
+  __ testptr(reg.first()->as_Register(), reg.first()->as_Register());
+  __ jccb(Assembler::equal, is_null);
+
+  __ push(c_rarg0);
+  __ push(c_rarg1);
+  __ push(c_rarg2);
+  __ push(c_rarg3);
+#ifdef _WIN64
+  // caller-saved registers on Windows
+  __ push(r10);
+  __ push(r11);
+#else
+  __ push(c_rarg4);
+  __ push(c_rarg5);
+#endif
+
+  if (reg.first()->as_Register() != c_rarg1) {
+    __ movptr(c_rarg1, reg.first()->as_Register());
+  }
+  __ movptr(c_rarg0, r15_thread);
+  __ call(RuntimeAddress(CAST_FROM_FN_PTR(address, SharedRuntime::pin_object)));
+
+#ifdef _WIN64
+  __ pop(r11);
+  __ pop(r10);
+#else
+  __ pop(c_rarg5);
+  __ pop(c_rarg4);
+#endif
+  __ pop(c_rarg3);
+  __ pop(c_rarg2);
+  __ pop(c_rarg1);
+  __ pop(c_rarg0);
+
+  if (on_stack) {
+    __ movptr(Address(rbp, reg2offset_in(in_reg.first())), rax);
+    __ bind(is_null);
+  } else {
+    __ movptr(reg.first()->as_Register(), rax);
+
+    // save on stack for unpinning later
+    __ bind(is_null);
+    assert(reg.first()->is_Register(), "Must be a register");
+    int offset = pinned_slot * VMRegImpl::stack_slot_size;
+    pinned_slot += VMRegImpl::slots_per_word;
+    __ movq(Address(rsp, offset), rax);
+  }
+  __ block_comment("} pin_critical_native_array");
+}
+
+// Unpin array argument of java critical method
+static void unpin_critical_native_array(MacroAssembler* masm,
+                                        VMRegPair reg,
+                                        int& pinned_slot) {
+  assert(UseShenandoahGC, "only supported in Shenandoah for now");
+  __ block_comment("unpin_critical_native_array {");
+  Label is_null;
+
+  if (reg.first()->is_stack()) {
+    __ movptr(c_rarg1, Address(rbp, reg2offset_in(reg.first())));
+  } else {
+    int offset = pinned_slot * VMRegImpl::stack_slot_size;
+    pinned_slot += VMRegImpl::slots_per_word;
+    __ movq(c_rarg1, Address(rsp, offset));
+  }
+  __ testptr(c_rarg1, c_rarg1);
+  __ jccb(Assembler::equal, is_null);
+
+  __ movptr(c_rarg0, r15_thread);
+  __ call(RuntimeAddress(CAST_FROM_FN_PTR(address, SharedRuntime::unpin_object)));
+
+  __ bind(is_null);
+  __ block_comment("} unpin_critical_native_array");
+}
 
 // Check GCLocker::needs_gc and enter the runtime if it's true.  This
 // keeps a new JNI critical region from starting until a GC has been
@@ -2130,7 +2227,7 @@
 
   const Register oop_handle_reg = r14;
 
-  if (is_critical_native) {
+  if (is_critical_native && !Universe::heap()->supports_object_pinning()) {
     check_needs_gc_for_critical_native(masm, stack_slots, total_c_args, total_in_args,
                                        oop_handle_offset, oop_maps, in_regs, in_sig_bt);
   }
@@ -2187,6 +2284,11 @@
   // the incoming and outgoing registers are offset upwards and for
   // critical natives they are offset down.
   GrowableArray<int> arg_order(2 * total_in_args);
+  // Inbound arguments that need to be pinned for critical natives
+  GrowableArray<int> pinned_args(total_in_args);
+  // Current stack slot for storing register based array argument
+  int pinned_slot = oop_handle_offset;
+
   VMRegPair tmp_vmreg;
   tmp_vmreg.set2(rbx->as_VMReg());
 
@@ -2234,6 +2336,12 @@
     switch (in_sig_bt[i]) {
       case T_ARRAY:
         if (is_critical_native) {
+          // pin before unpack
+          if (Universe::heap()->supports_object_pinning()) {
+            assert(pinned_slot <= stack_slots, "overflow");
+            pin_critical_native_array(masm, in_regs[i], pinned_slot);
+            pinned_args.append(i);
+          }
           unpack_array_argument(masm, in_regs[i], in_elem_bt[i], out_regs[c_arg + 1], out_regs[c_arg]);
           c_arg++;
 #ifdef ASSERT
@@ -2450,6 +2558,19 @@
   default       : ShouldNotReachHere();
   }
 
+  // unpin pinned arguments
+  pinned_slot = oop_handle_offset;
+  if (pinned_args.length() > 0) {
+    // save return value that may be overwritten otherwise.
+    save_native_result(masm, ret_type, stack_slots);
+    for (int index = 0; index < pinned_args.length(); index ++) {
+      int i = pinned_args.at(index);
+      assert(pinned_slot <= stack_slots, "overflow");
+      unpin_critical_native_array(masm, in_regs[i], pinned_slot);
+    }
+    restore_native_result(masm, ret_type, stack_slots);
+  }
+
   // Switch thread to "native transition" state before reading the synchronization state.
   // This additional state is necessary because reading and testing the synchronization
   // state is not atomic w.r.t. GC, as this scenario demonstrates:
--- old/src/hotspot/share/adlc/formssel.cpp	2020-01-17 17:14:16.026116928 +0100
+++ new/src/hotspot/share/adlc/formssel.cpp	2020-01-17 17:14:15.929116933 +0100
@@ -778,6 +778,10 @@
        !strcmp(_matrule->_rChild->_opType,"LoadBarrierSlowReg") ||
        !strcmp(_matrule->_rChild->_opType,"LoadBarrierWeakSlowReg") ||
 #endif
+#if INCLUDE_SHENANDOAHGC
+       !strcmp(_matrule->_rChild->_opType,"ShenandoahCompareAndExchangeP") ||
+       !strcmp(_matrule->_rChild->_opType,"ShenandoahCompareAndExchangeN") ||
+#endif
        !strcmp(_matrule->_rChild->_opType,"CompareAndExchangeP") ||
        !strcmp(_matrule->_rChild->_opType,"CompareAndExchangeN")))  return true;
   else if ( is_ideal_load() == Form::idealP )                return true;
@@ -3502,6 +3506,9 @@
     "CompareAndSwapB", "CompareAndSwapS", "CompareAndSwapI", "CompareAndSwapL", "CompareAndSwapP", "CompareAndSwapN",
     "WeakCompareAndSwapB", "WeakCompareAndSwapS", "WeakCompareAndSwapI", "WeakCompareAndSwapL", "WeakCompareAndSwapP", "WeakCompareAndSwapN",
     "CompareAndExchangeB", "CompareAndExchangeS", "CompareAndExchangeI", "CompareAndExchangeL", "CompareAndExchangeP", "CompareAndExchangeN",
+#if INCLUDE_SHENANDOAHGC
+    "ShenandoahCompareAndSwapN", "ShenandoahCompareAndSwapP", "ShenandoahWeakCompareAndSwapP", "ShenandoahWeakCompareAndSwapN", "ShenandoahCompareAndExchangeP", "ShenandoahCompareAndExchangeN",
+#endif
     "StoreCM",
     "ClearArray",
     "GetAndSetB", "GetAndSetS", "GetAndAddI", "GetAndSetI", "GetAndSetP",
--- old/src/hotspot/share/ci/ciInstanceKlass.cpp	2020-01-17 17:14:16.660116893 +0100
+++ new/src/hotspot/share/ci/ciInstanceKlass.cpp	2020-01-17 17:14:16.560116899 +0100
@@ -554,6 +554,12 @@
   _has_injected_fields = has_injected_fields;
 }
 
+bool ciInstanceKlass::has_object_fields() const {
+  GUARDED_VM_ENTRY(
+      return get_instanceKlass()->nonstatic_oop_map_size() > 0;
+    );
+}
+
 // ------------------------------------------------------------------
 // ciInstanceKlass::find_method
 //
--- old/src/hotspot/share/ci/ciInstanceKlass.hpp	2020-01-17 17:14:17.247116861 +0100
+++ new/src/hotspot/share/ci/ciInstanceKlass.hpp	2020-01-17 17:14:17.148116866 +0100
@@ -202,6 +202,8 @@
     return _has_injected_fields > 0 ? true : false;
   }
 
+  bool has_object_fields() const;
+
   // nth nonstatic field (presented by ascending address)
   ciField* nonstatic_field_at(int i) {
     assert(_nonstatic_fields != NULL, "");
--- old/src/hotspot/share/code/codeBlob.cpp	2020-01-17 17:14:17.827116829 +0100
+++ new/src/hotspot/share/code/codeBlob.cpp	2020-01-17 17:14:17.727116834 +0100
@@ -31,6 +31,7 @@
 #include "code/vtableStubs.hpp"
 #include "compiler/disassembler.hpp"
 #include "interpreter/bytecode.hpp"
+#include "interpreter/interpreter.hpp"
 #include "memory/allocation.inline.hpp"
 #include "memory/heap.hpp"
 #include "memory/resourceArea.hpp"
--- old/src/hotspot/share/code/codeCache.hpp	2020-01-17 17:14:18.407116797 +0100
+++ new/src/hotspot/share/code/codeCache.hpp	2020-01-17 17:14:18.310116802 +0100
@@ -73,6 +73,7 @@
 
 class OopClosure;
 class KlassDepChange;
+class ShenandoahParallelCodeHeapIterator;
 
 class CodeCache : AllStatic {
   friend class VMStructs;
@@ -80,6 +81,7 @@
   template <class T, class Filter> friend class CodeBlobIterator;
   friend class WhiteBox;
   friend class CodeCacheLoader;
+  friend class ShenandoahParallelCodeHeapIterator;
  private:
   // CodeHeaps of the cache
   static GrowableArray<CodeHeap*>* _heaps;
--- old/src/hotspot/share/gc/shared/barrierSetConfig.hpp	2020-01-17 17:14:18.992116765 +0100
+++ new/src/hotspot/share/gc/shared/barrierSetConfig.hpp	2020-01-17 17:14:18.891116770 +0100
@@ -32,6 +32,7 @@
   f(CardTableBarrierSet)                             \
   EPSILONGC_ONLY(f(EpsilonBarrierSet))               \
   G1GC_ONLY(f(G1BarrierSet))                         \
+  SHENANDOAHGC_ONLY(f(ShenandoahBarrierSet))         \
   ZGC_ONLY(f(ZBarrierSet))
 
 #define FOR_EACH_ABSTRACT_BARRIER_SET_DO(f)          \
--- old/src/hotspot/share/gc/shared/barrierSetConfig.inline.hpp	2020-01-17 17:14:19.569116733 +0100
+++ new/src/hotspot/share/gc/shared/barrierSetConfig.inline.hpp	2020-01-17 17:14:19.471116738 +0100
@@ -36,6 +36,9 @@
 #if INCLUDE_G1GC
 #include "gc/g1/g1BarrierSet.inline.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
+#endif
 #if INCLUDE_ZGC
 #include "gc/z/zBarrierSet.inline.hpp"
 #endif
--- old/src/hotspot/share/gc/shared/collectedHeap.hpp	2020-01-17 17:14:20.148116701 +0100
+++ new/src/hotspot/share/gc/shared/collectedHeap.hpp	2020-01-17 17:14:20.049116706 +0100
@@ -89,6 +89,7 @@
 //     CMSHeap
 //   G1CollectedHeap
 //   ParallelScavengeHeap
+//   ShenandoahHeap
 //   ZCollectedHeap
 //
 class CollectedHeap : public CHeapObj<mtInternal> {
@@ -178,7 +179,8 @@
     CMS,
     G1,
     Epsilon,
-    Z
+    Z,
+    Shenandoah
   };
 
   static inline size_t filler_array_max_size() {
--- old/src/hotspot/share/gc/shared/gcCause.cpp	2020-01-17 17:14:20.737116668 +0100
+++ new/src/hotspot/share/gc/shared/gcCause.cpp	2020-01-17 17:14:20.637116674 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -105,6 +105,21 @@
     case _dcmd_gc_run:
       return "Diagnostic Command";
 
+    case _shenandoah_allocation_failure_evac:
+      return "Allocation Failure During Evacuation";
+
+    case _shenandoah_stop_vm:
+      return "Stopping VM";
+
+    case _shenandoah_concurrent_gc:
+      return "Concurrent GC";
+
+    case _shenandoah_traversal_gc:
+      return "Traversal GC";
+
+    case _shenandoah_upgrade_to_full_gc:
+      return "Upgrade To Full GC";
+
     case _z_timer:
       return "Timer";
 
--- old/src/hotspot/share/gc/shared/gcCause.hpp	2020-01-17 17:14:21.328116636 +0100
+++ new/src/hotspot/share/gc/shared/gcCause.hpp	2020-01-17 17:14:21.223116642 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -78,6 +78,12 @@
 
     _dcmd_gc_run,
 
+    _shenandoah_stop_vm,
+    _shenandoah_allocation_failure_evac,
+    _shenandoah_concurrent_gc,
+    _shenandoah_traversal_gc,
+    _shenandoah_upgrade_to_full_gc,
+
     _z_timer,
     _z_warmup,
     _z_allocation_rate,
@@ -121,7 +127,8 @@
     // _allocation_failure is the generic cause a collection for allocation failure
     // _adaptive_size_policy is for a collecton done before a full GC
     return (cause == GCCause::_allocation_failure ||
-            cause == GCCause::_adaptive_size_policy);
+            cause == GCCause::_adaptive_size_policy ||
+            cause == GCCause::_shenandoah_allocation_failure_evac);
   }
 
   // Return a string describing the GCCause.
--- old/src/hotspot/share/gc/shared/gcConfig.cpp	2020-01-17 17:14:21.910116604 +0100
+++ new/src/hotspot/share/gc/shared/gcConfig.cpp	2020-01-17 17:14:21.810116609 +0100
@@ -43,6 +43,9 @@
 #if INCLUDE_SERIALGC
 #include "gc/serial/serialArguments.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/shenandoahArguments.hpp"
+#endif
 #if INCLUDE_ZGC
 #include "gc/z/zArguments.hpp"
 #endif
@@ -57,23 +60,25 @@
       _flag(flag), _name(name), _arguments(arguments), _hs_err_name(hs_err_name) {}
 };
 
-     CMSGC_ONLY(static CMSArguments      cmsArguments;)
- EPSILONGC_ONLY(static EpsilonArguments  epsilonArguments;)
-      G1GC_ONLY(static G1Arguments       g1Arguments;)
-PARALLELGC_ONLY(static ParallelArguments parallelArguments;)
-  SERIALGC_ONLY(static SerialArguments   serialArguments;)
-       ZGC_ONLY(static ZArguments        zArguments;)
+       CMSGC_ONLY(static CMSArguments      cmsArguments;)
+   EPSILONGC_ONLY(static EpsilonArguments  epsilonArguments;)
+        G1GC_ONLY(static G1Arguments       g1Arguments;)
+  PARALLELGC_ONLY(static ParallelArguments parallelArguments;)
+    SERIALGC_ONLY(static SerialArguments   serialArguments;)
+SHENANDOAHGC_ONLY(static ShenandoahArguments shenandoahArguments;)
+         ZGC_ONLY(static ZArguments        zArguments;)
 
 // Table of supported GCs, for translating between command
 // line flag, CollectedHeap::Name and GCArguments instance.
 static const SupportedGC SupportedGCs[] = {
-       CMSGC_ONLY_ARG(SupportedGC(UseConcMarkSweepGC, CollectedHeap::CMS,      cmsArguments,      "concurrent mark sweep gc"))
-   EPSILONGC_ONLY_ARG(SupportedGC(UseEpsilonGC,       CollectedHeap::Epsilon,  epsilonArguments,  "epsilon gc"))
-        G1GC_ONLY_ARG(SupportedGC(UseG1GC,            CollectedHeap::G1,       g1Arguments,       "g1 gc"))
-  PARALLELGC_ONLY_ARG(SupportedGC(UseParallelGC,      CollectedHeap::Parallel, parallelArguments, "parallel gc"))
-  PARALLELGC_ONLY_ARG(SupportedGC(UseParallelOldGC,   CollectedHeap::Parallel, parallelArguments, "parallel gc"))
-    SERIALGC_ONLY_ARG(SupportedGC(UseSerialGC,        CollectedHeap::Serial,   serialArguments,   "serial gc"))
-         ZGC_ONLY_ARG(SupportedGC(UseZGC,             CollectedHeap::Z,        zArguments,        "z gc"))
+       CMSGC_ONLY_ARG(SupportedGC(UseConcMarkSweepGC, CollectedHeap::CMS,        cmsArguments,        "concurrent mark sweep gc"))
+   EPSILONGC_ONLY_ARG(SupportedGC(UseEpsilonGC,       CollectedHeap::Epsilon,    epsilonArguments,    "epsilon gc"))
+        G1GC_ONLY_ARG(SupportedGC(UseG1GC,            CollectedHeap::G1,         g1Arguments,         "g1 gc"))
+  PARALLELGC_ONLY_ARG(SupportedGC(UseParallelGC,      CollectedHeap::Parallel,   parallelArguments,   "parallel gc"))
+  PARALLELGC_ONLY_ARG(SupportedGC(UseParallelOldGC,   CollectedHeap::Parallel,   parallelArguments,   "parallel gc"))
+    SERIALGC_ONLY_ARG(SupportedGC(UseSerialGC,        CollectedHeap::Serial,     serialArguments,     "serial gc"))
+SHENANDOAHGC_ONLY_ARG(SupportedGC(UseShenandoahGC,    CollectedHeap::Shenandoah, shenandoahArguments, "shenandoah gc"))
+         ZGC_ONLY_ARG(SupportedGC(UseZGC,             CollectedHeap::Z,          zArguments,          "z gc"))
 };
 
 #define FOR_EACH_SUPPORTED_GC(var)                                          \
@@ -90,14 +95,15 @@
 bool GCConfig::_gc_selected_ergonomically = false;
 
 void GCConfig::fail_if_unsupported_gc_is_selected() {
-  NOT_CMSGC(     FAIL_IF_SELECTED(UseConcMarkSweepGC, true));
-  NOT_EPSILONGC( FAIL_IF_SELECTED(UseEpsilonGC,       true));
-  NOT_G1GC(      FAIL_IF_SELECTED(UseG1GC,            true));
-  NOT_PARALLELGC(FAIL_IF_SELECTED(UseParallelGC,      true));
-  NOT_PARALLELGC(FAIL_IF_SELECTED(UseParallelOldGC,   true));
-  NOT_SERIALGC(  FAIL_IF_SELECTED(UseSerialGC,        true));
-  NOT_SERIALGC(  FAIL_IF_SELECTED(UseParallelOldGC,   false));
-  NOT_ZGC(       FAIL_IF_SELECTED(UseZGC,             true));
+  NOT_CMSGC(       FAIL_IF_SELECTED(UseConcMarkSweepGC, true));
+  NOT_EPSILONGC(   FAIL_IF_SELECTED(UseEpsilonGC,       true));
+  NOT_G1GC(        FAIL_IF_SELECTED(UseG1GC,            true));
+  NOT_PARALLELGC(  FAIL_IF_SELECTED(UseParallelGC,      true));
+  NOT_PARALLELGC(  FAIL_IF_SELECTED(UseParallelOldGC,   true));
+  NOT_SERIALGC(    FAIL_IF_SELECTED(UseSerialGC,        true));
+  NOT_SERIALGC(    FAIL_IF_SELECTED(UseParallelOldGC,   false));
+  NOT_SHENANDOAHGC(FAIL_IF_SELECTED(UseShenandoahGC,    true));
+  NOT_ZGC(         FAIL_IF_SELECTED(UseZGC,             true));
 }
 
 void GCConfig::select_gc_ergonomically() {
--- old/src/hotspot/share/gc/shared/gcConfiguration.cpp	2020-01-17 17:14:22.491116572 +0100
+++ new/src/hotspot/share/gc/shared/gcConfiguration.cpp	2020-01-17 17:14:22.391116577 +0100
@@ -43,7 +43,7 @@
     return ParNew;
   }
 
-  if (UseZGC) {
+  if (UseZGC || UseShenandoahGC) {
     return NA;
   }
 
@@ -67,6 +67,10 @@
     return Z;
   }
 
+  if (UseShenandoahGC) {
+    return Shenandoah;
+  }
+
   return SerialOld;
 }
 
--- old/src/hotspot/share/gc/shared/gcName.hpp	2020-01-17 17:14:23.072116540 +0100
+++ new/src/hotspot/share/gc/shared/gcName.hpp	2020-01-17 17:14:22.972116545 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -39,6 +39,7 @@
   G1Old,
   G1Full,
   Z,
+  Shenandoah,
   NA,
   GCNameEndSentinel
 };
@@ -58,6 +59,7 @@
       case G1Old: return "G1Old";
       case G1Full: return "G1Full";
       case Z: return "Z";
+      case Shenandoah: return "Shenandoah";
       case NA: return "N/A";
       default: ShouldNotReachHere(); return NULL;
     }
--- old/src/hotspot/share/gc/shared/gc_globals.hpp	2020-01-17 17:14:23.649116508 +0100
+++ new/src/hotspot/share/gc/shared/gc_globals.hpp	2020-01-17 17:14:23.547116514 +0100
@@ -41,6 +41,9 @@
 #if INCLUDE_SERIALGC
 #include "gc/serial/serial_globals.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/shenandoah_globals.hpp"
+#endif
 #if INCLUDE_ZGC
 #include "gc/z/z_globals.hpp"
 #endif
@@ -140,6 +143,22 @@
     constraint,                                                             \
     writeable))                                                             \
                                                                             \
+  SHENANDOAHGC_ONLY(GC_SHENANDOAH_FLAGS(                                    \
+    develop,                                                                \
+    develop_pd,                                                             \
+    product,                                                                \
+    product_pd,                                                             \
+    diagnostic,                                                             \
+    diagnostic_pd,                                                          \
+    experimental,                                                           \
+    notproduct,                                                             \
+    manageable,                                                             \
+    product_rw,                                                             \
+    lp64_product,                                                           \
+    range,                                                                  \
+    constraint,                                                             \
+    writeable))                                                             \
+                                                                            \
   ZGC_ONLY(GC_Z_FLAGS(                                                      \
     develop,                                                                \
     develop_pd,                                                             \
@@ -179,6 +198,9 @@
   experimental(bool, UseZGC, false,                                         \
           "Use the Z garbage collector")                                    \
                                                                             \
+  experimental(bool, UseShenandoahGC, false,                                \
+          "Use the Shenandoah garbage collector")                           \
+                                                                            \
   product(uint, ParallelGCThreads, 0,                                       \
           "Number of parallel threads parallel gc will use")                \
           constraint(ParallelGCThreadsConstraintFunc,AfterErgo)             \
--- old/src/hotspot/share/gc/shared/referenceProcessor.cpp	2020-01-17 17:14:24.245116475 +0100
+++ new/src/hotspot/share/gc/shared/referenceProcessor.cpp	2020-01-17 17:14:24.141116481 +0100
@@ -1156,7 +1156,7 @@
       // Check assumption that an object is not potentially
       // discovered twice except by concurrent collectors that potentially
       // trace the same Reference object twice.
-      assert(UseConcMarkSweepGC || UseG1GC,
+      assert(UseConcMarkSweepGC || UseG1GC || UseShenandoahGC,
              "Only possible with a concurrent marking collector");
       return true;
     }
--- old/src/hotspot/share/gc/shared/taskqueue.hpp	2020-01-17 17:14:24.834116443 +0100
+++ new/src/hotspot/share/gc/shared/taskqueue.hpp	2020-01-17 17:14:24.734116448 +0100
@@ -357,7 +357,8 @@
   static int randomParkAndMiller(int* seed0);
 public:
   // Returns "true" if some TaskQueue in the set contains a task.
-  virtual bool peek() = 0;
+  virtual bool   peek() = 0;
+  virtual size_t tasks() = 0;
 };
 
 template <MEMFLAGS F> class TaskQueueSetSuperImpl: public CHeapObj<F>, public TaskQueueSetSuper {
@@ -389,6 +390,7 @@
   bool steal(uint queue_num, int* seed, E& t);
 
   bool peek();
+  size_t tasks();
 
   uint size() const { return _n; }
 };
@@ -414,6 +416,16 @@
   return false;
 }
 
+template<class T, MEMFLAGS F>
+size_t GenericTaskQueueSet<T, F>::tasks() {
+  size_t n = 0;
+  for (uint j = 0; j < _n; j++) {
+    n += _queues[j]->size();
+  }
+  return n;
+}
+
+
 // When to terminate from the termination protocol.
 class TerminatorTerminator: public CHeapObj<mtInternal> {
 public:
@@ -426,7 +438,7 @@
 #undef TRACESPINNING
 
 class ParallelTaskTerminator: public StackObj {
-private:
+protected:
   uint _n_threads;
   TaskQueueSetSuper* _queue_set;
 
@@ -462,7 +474,7 @@
   // As above, but it also terminates if the should_exit_termination()
   // method of the terminator parameter returns true. If terminator is
   // NULL, then it is ignored.
-  bool offer_termination(TerminatorTerminator* terminator);
+  virtual bool offer_termination(TerminatorTerminator* terminator);
 
   // Reset the terminator, so that it may be reused again.
   // The caller is responsible for ensuring that this is done
--- old/src/hotspot/share/gc/shared/vmStructs_gc.hpp	2020-01-17 17:14:25.413116411 +0100
+++ new/src/hotspot/share/gc/shared/vmStructs_gc.hpp	2020-01-17 17:14:25.315116416 +0100
@@ -50,6 +50,9 @@
 #include "gc/serial/defNewGeneration.hpp"
 #include "gc/serial/vmStructs_serial.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/vmStructs_shenandoah.hpp"
+#endif
 #if INCLUDE_ZGC
 #include "gc/z/vmStructs_z.hpp"
 #endif
@@ -73,6 +76,9 @@
   SERIALGC_ONLY(VM_STRUCTS_SERIALGC(nonstatic_field,                                                                                 \
                                     volatile_nonstatic_field,                                                                        \
                                     static_field))                                                                                   \
+  SHENANDOAHGC_ONLY(VM_STRUCTS_SHENANDOAH(nonstatic_field,                                                                           \
+                               volatile_nonstatic_field,                                                                             \
+                               static_field))                                                                                        \
   ZGC_ONLY(VM_STRUCTS_ZGC(nonstatic_field,                                                                                           \
                           volatile_nonstatic_field,                                                                                  \
                           static_field))                                                                                             \
@@ -178,6 +184,9 @@
   SERIALGC_ONLY(VM_TYPES_SERIALGC(declare_type,                           \
                                   declare_toplevel_type,                  \
                                   declare_integer_type))                  \
+  SHENANDOAHGC_ONLY(VM_TYPES_SHENANDOAH(declare_type,                     \
+                             declare_toplevel_type,                       \
+                             declare_integer_type))                       \
   ZGC_ONLY(VM_TYPES_ZGC(declare_type,                                     \
                         declare_toplevel_type,                            \
                         declare_integer_type))                            \
@@ -253,6 +262,8 @@
                                               declare_constant_with_value)) \
   SERIALGC_ONLY(VM_INT_CONSTANTS_SERIALGC(declare_constant,                 \
                                           declare_constant_with_value))     \
+  SHENANDOAHGC_ONLY(VM_INT_CONSTANTS_SHENANDOAH(declare_constant,           \
+                                     declare_constant_with_value))          \
   ZGC_ONLY(VM_INT_CONSTANTS_ZGC(declare_constant,                           \
                                 declare_constant_with_value))               \
                                                                             \
--- old/src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp	2020-01-17 17:14:25.993116379 +0100
+++ new/src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp	2020-01-17 17:14:25.892116384 +0100
@@ -129,7 +129,7 @@
   ZBarrierSetC2State* s = bs->state();
   if (s->load_barrier_count() >= 2) {
     Compile::TracePhase tp("idealLoop", &C->timers[Phase::_t_idealLoop]);
-    PhaseIdealLoop ideal_loop(igvn, true, false, true);
+    PhaseIdealLoop ideal_loop(igvn, LoopOptsZgcLastRound);
     if (C->major_progress()) C->print_method(PHASE_PHASEIDEALLOOP_ITERATIONS, 2);
   }
 }
--- old/src/hotspot/share/jfr/leakprofiler/leakProfiler.cpp	2020-01-17 17:14:26.590116346 +0100
+++ new/src/hotspot/share/jfr/leakprofiler/leakProfiler.cpp	2020-01-17 17:14:26.488116352 +0100
@@ -53,6 +53,11 @@
     return false;
   }
 
+  if (UseShenandoahGC) {
+    log_warning(jfr)("LeakProfiler is currently not supported in combination with Shenandoah GC");
+    return false;
+  }
+
   assert(!is_running(), "invariant");
   assert(sample_count > 0, "invariant");
 
--- old/src/hotspot/share/jfr/metadata/metadata.xml	2020-01-17 17:14:27.167116314 +0100
+++ new/src/hotspot/share/jfr/metadata/metadata.xml	2020-01-17 17:14:27.069116320 +0100
@@ -922,6 +922,27 @@
     <Field type="ulong" name="value" label="Value" />
   </Event>
 
+  <Event name="ShenandoahHeapRegionStateChange" category="Java Virtual Machine, GC, Detailed" label="Shenandoah Heap Region State Change" description="Information about a Shenandoah heap region state change"
+    startTime="false">
+    <Field type="uint" name="index" label="Index" />
+    <Field type="ShenandoahHeapRegionState" name="from" label="From" />
+    <Field type="ShenandoahHeapRegionState" name="to" label="To" />
+    <Field type="ulong" contentType="address" name="start" label="Start" />
+    <Field type="ulong" contentType="bytes" name="used" label="Used" />
+  </Event>
+
+  <Event name="ShenandoahHeapRegionInformation" category="Java Virtual Machine, GC, Detailed" label="Shenandoah Heap Region Information" description="Information about a specific heap region in the Shenandoah GC"
+    period="everyChunk">
+    <Field type="uint" name="index" label="Index" />
+    <Field type="ShenandoahHeapRegionState" name="state" label="State" />
+    <Field type="ulong" contentType="address" name="start" label="Start" />
+    <Field type="ulong" contentType="bytes" name="used" label="Used" />
+  </Event>
+
+  <Type name="ShenandoahHeapRegionState" label="Shenandoah Heap Region State">
+    <Field type="string" name="state" label="State" />
+  </Type>
+
   <Type name="ZStatisticsCounterType" label="Z Statistics Counter">
     <Field type="string" name="counter" label="Counter" />
   </Type>
--- old/src/hotspot/share/jfr/periodic/jfrPeriodic.cpp	2020-01-17 17:14:27.786116280 +0100
+++ new/src/hotspot/share/jfr/periodic/jfrPeriodic.cpp	2020-01-17 17:14:27.684116286 +0100
@@ -63,6 +63,9 @@
 #if INCLUDE_G1GC
 #include "gc/g1/g1HeapRegionEventSender.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/shenandoahJfrSupport.hpp"
+#endif
 
 /**
  *  JfrPeriodic class
@@ -574,3 +577,14 @@
   event.set_flushingEnabled(UseCodeCacheFlushing);
   event.commit();
 }
+
+
+TRACE_REQUEST_FUNC(ShenandoahHeapRegionInformation) {
+#if INCLUDE_SHENANDOAHGC
+  if (UseShenandoahGC) {
+    VM_ShenandoahSendHeapRegionInfoEvents op;
+    VMThread::execute(&op);
+  }
+#endif
+}
+
--- old/src/hotspot/share/memory/metaspace.hpp	2020-01-17 17:14:28.369116248 +0100
+++ new/src/hotspot/share/memory/metaspace.hpp	2020-01-17 17:14:28.270116253 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -235,6 +235,7 @@
 class ClassLoaderMetaspace : public CHeapObj<mtClass> {
   friend class CollectedHeap; // For expand_and_allocate()
   friend class ZCollectedHeap; // For expand_and_allocate()
+  friend class ShenandoahHeap; // For expand_and_allocate()
   friend class Metaspace;
   friend class MetaspaceUtils;
   friend class metaspace::PrintCLDMetaspaceInfoClosure;
--- old/src/hotspot/share/opto/arraycopynode.cpp	2020-01-17 17:14:28.955116216 +0100
+++ new/src/hotspot/share/opto/arraycopynode.cpp	2020-01-17 17:14:28.857116221 +0100
@@ -30,6 +30,9 @@
 #include "opto/graphKit.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "utilities/macros.hpp"
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 ArrayCopyNode::ArrayCopyNode(Compile* C, bool alloc_tightly_coupled, bool has_negative_length_guard)
   : CallNode(arraycopy_type(), NULL, TypeRawPtr::BOTTOM),
@@ -205,6 +208,11 @@
 
     Node* v = LoadNode::make(*phase, ctl, mem->memory_at(fieldidx), next_src, adr_type, type, bt, MemNode::unordered);
     v = phase->transform(v);
+#if INCLUDE_SHENANDOAHGC
+    if (UseShenandoahGC && bt == T_OBJECT) {
+      v = ShenandoahBarrierSetC2::bsc2()->arraycopy_load_reference_barrier(phase, v);
+    }
+#endif
     Node* s = StoreNode::make(*phase, ctl, mem->memory_at(fieldidx), next_dest, adr_type, v, bt, MemNode::unordered);
     s = phase->transform(s);
     mem->set_memory_at(fieldidx, s);
@@ -373,6 +381,11 @@
     if (count > 0) {
       Node* v = LoadNode::make(*phase, forward_ctl, start_mem_src, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
       v = phase->transform(v);
+#if INCLUDE_SHENANDOAHGC
+      if (UseShenandoahGC && copy_type == T_OBJECT) {
+        v = ShenandoahBarrierSetC2::bsc2()->arraycopy_load_reference_barrier(phase, v);
+      }
+#endif
       mem = StoreNode::make(*phase, forward_ctl, mem, adr_dest, atp_dest, v, copy_type, MemNode::unordered);
       mem = phase->transform(mem);
       for (int i = 1; i < count; i++) {
@@ -381,6 +394,11 @@
         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
         v = LoadNode::make(*phase, forward_ctl, same_alias ? mem : start_mem_src, next_src, atp_src, value_type, copy_type, MemNode::unordered);
         v = phase->transform(v);
+#if INCLUDE_SHENANDOAHGC
+        if (UseShenandoahGC && copy_type == T_OBJECT) {
+          v = ShenandoahBarrierSetC2::bsc2()->arraycopy_load_reference_barrier(phase, v);
+        }
+#endif
         mem = StoreNode::make(*phase, forward_ctl,mem,next_dest,atp_dest,v, copy_type, MemNode::unordered);
         mem = phase->transform(mem);
       }
@@ -422,11 +440,21 @@
         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
         Node* v = LoadNode::make(*phase, backward_ctl, same_alias ? mem : start_mem_src, next_src, atp_src, value_type, copy_type, MemNode::unordered);
         v = phase->transform(v);
+#if INCLUDE_SHENANDOAHGC
+        if (UseShenandoahGC && copy_type == T_OBJECT) {
+          v = ShenandoahBarrierSetC2::bsc2()->arraycopy_load_reference_barrier(phase, v);
+        }
+#endif
         mem = StoreNode::make(*phase, backward_ctl,mem,next_dest,atp_dest,v, copy_type, MemNode::unordered);
         mem = phase->transform(mem);
       }
       Node* v = LoadNode::make(*phase, backward_ctl, same_alias ? mem : start_mem_src, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
       v = phase->transform(v);
+#if INCLUDE_SHENANDOAHGC
+      if (UseShenandoahGC && copy_type == T_OBJECT) {
+        v = ShenandoahBarrierSetC2::bsc2()->arraycopy_load_reference_barrier(phase, v);
+      }
+#endif
       mem = StoreNode::make(*phase, backward_ctl, mem, adr_dest, atp_dest, v, copy_type, MemNode::unordered);
       mem = phase->transform(mem);
     } else if(can_reshape) {
@@ -485,7 +513,8 @@
   } else {
     if (in(TypeFunc::Control) != ctl) {
       // we can't return new memory and control from Ideal at parse time
-      assert(!is_clonebasic(), "added control for clone?");
+      assert(!is_clonebasic() || UseShenandoahGC, "added control for clone?");
+      phase->record_for_igvn(this);
       return false;
     }
   }
--- old/src/hotspot/share/opto/cfgnode.hpp	2020-01-17 17:14:29.535116184 +0100
+++ new/src/hotspot/share/opto/cfgnode.hpp	2020-01-17 17:14:29.439116189 +0100
@@ -303,7 +303,6 @@
 protected:
   ProjNode* range_check_trap_proj(int& flip, Node*& l, Node*& r);
   Node* Ideal_common(PhaseGVN *phase, bool can_reshape);
-  Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
   Node* search_identical(int dist);
 
 public:
@@ -391,6 +390,7 @@
   virtual const RegMask &out_RegMask() const;
   Node* fold_compares(PhaseIterGVN* phase);
   static Node* up_one_dom(Node* curr, bool linear_only = false);
+  Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
 
   // Takes the type of val and filters it through the test represented
   // by if_proj and returns a more refined type if one is produced.
--- old/src/hotspot/share/opto/classes.cpp	2020-01-17 17:14:30.125116151 +0100
+++ new/src/hotspot/share/opto/classes.cpp	2020-01-17 17:14:30.024116157 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -51,6 +51,9 @@
 #if INCLUDE_ZGC
 #include "gc/z/c2/zBarrierSetC2.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 // ----------------------------------------------------------------------------
 // Build a table of virtual functions to map from Nodes to dense integer
--- old/src/hotspot/share/opto/classes.hpp	2020-01-17 17:14:30.698116120 +0100
+++ new/src/hotspot/share/opto/classes.hpp	2020-01-17 17:14:30.602116125 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -265,6 +265,19 @@
 macro(RoundFloat)
 macro(SafePoint)
 macro(SafePointScalarObject)
+#if INCLUDE_SHENANDOAHGC
+#define shmacro(x) macro(x)
+#else
+#define shmacro(x) optionalmacro(x)
+#endif
+shmacro(ShenandoahCompareAndExchangeP)
+shmacro(ShenandoahCompareAndExchangeN)
+shmacro(ShenandoahCompareAndSwapN)
+shmacro(ShenandoahCompareAndSwapP)
+shmacro(ShenandoahWeakCompareAndSwapN)
+shmacro(ShenandoahWeakCompareAndSwapP)
+shmacro(ShenandoahEnqueueBarrier)
+shmacro(ShenandoahLoadReferenceBarrier)
 macro(SCMemProj)
 macro(SqrtD)
 macro(SqrtF)
--- old/src/hotspot/share/opto/compile.cpp	2020-01-17 17:14:31.275116088 +0100
+++ new/src/hotspot/share/opto/compile.cpp	2020-01-17 17:14:31.176116093 +0100
@@ -82,6 +82,9 @@
 #if INCLUDE_ZGC
 #include "gc/z/c2/zBarrierSetC2.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 
 // -------------------- Compile::mach_constant_base_node -----------------------
@@ -2104,7 +2107,7 @@
         // PhaseIdealLoop is expensive so we only try it once we are
         // out of live nodes and we only try it again if the previous
         // helped got the number of nodes down significantly
-        PhaseIdealLoop ideal_loop( igvn, false, true );
+        PhaseIdealLoop ideal_loop(igvn, LoopOptsNone);
         if (failing())  return;
         low_live_nodes = live_nodes();
         _major_progress = true;
@@ -2155,6 +2158,21 @@
 }
 
 
+bool Compile::optimize_loops(int& loop_opts_cnt, PhaseIterGVN& igvn, LoopOptsMode mode) {
+  if(loop_opts_cnt > 0) {
+    debug_only( int cnt = 0; );
+    while(major_progress() && (loop_opts_cnt > 0)) {
+      TracePhase tp("idealLoop", &timers[_t_idealLoop]);
+      assert( cnt++ < 40, "infinite cycle in loop optimization" );
+      PhaseIdealLoop ideal_loop(igvn, mode);
+      loop_opts_cnt--;
+      if (failing())  return false;
+      if (major_progress()) print_method(PHASE_PHASEIDEALLOOP_ITERATIONS, 2);
+    }
+  }
+  return true;
+}
+
 //------------------------------Optimize---------------------------------------
 // Given a graph, optimize it.
 void Compile::Optimize() {
@@ -2193,10 +2211,10 @@
     igvn.optimize();
   }
 
-  print_method(PHASE_ITER_GVN1, 2);
-
   if (failing())  return;
 
+  print_method(PHASE_ITER_GVN1, 2);
+
   inline_incrementally(igvn);
 
   print_method(PHASE_INCREMENTAL_INLINE, 2);
@@ -2245,7 +2263,7 @@
     if (has_loops()) {
       // Cleanup graph (remove dead nodes).
       TracePhase tp("idealLoop", &timers[_t_idealLoop]);
-      PhaseIdealLoop ideal_loop( igvn, false, true );
+      PhaseIdealLoop ideal_loop(igvn, LoopOptsNone);
       if (major_progress()) print_method(PHASE_PHASEIDEAL_BEFORE_EA, 2);
       if (failing())  return;
     }
@@ -2280,7 +2298,7 @@
   if((loop_opts_cnt > 0) && (has_loops() || has_split_ifs())) {
     {
       TracePhase tp("idealLoop", &timers[_t_idealLoop]);
-      PhaseIdealLoop ideal_loop( igvn, true );
+      PhaseIdealLoop ideal_loop(igvn, LoopOptsDefault);
       loop_opts_cnt--;
       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP1, 2);
       if (failing())  return;
@@ -2288,7 +2306,7 @@
     // Loop opts pass if partial peeling occurred in previous pass
     if(PartialPeelLoop && major_progress() && (loop_opts_cnt > 0)) {
       TracePhase tp("idealLoop", &timers[_t_idealLoop]);
-      PhaseIdealLoop ideal_loop( igvn, false );
+      PhaseIdealLoop ideal_loop(igvn, LoopOptsSkipSplitIf);
       loop_opts_cnt--;
       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP2, 2);
       if (failing())  return;
@@ -2296,7 +2314,7 @@
     // Loop opts pass for loop-unrolling before CCP
     if(major_progress() && (loop_opts_cnt > 0)) {
       TracePhase tp("idealLoop", &timers[_t_idealLoop]);
-      PhaseIdealLoop ideal_loop( igvn, false );
+      PhaseIdealLoop ideal_loop(igvn, LoopOptsSkipSplitIf);
       loop_opts_cnt--;
       if (major_progress()) print_method(PHASE_PHASEIDEALLOOP3, 2);
     }
@@ -2332,16 +2350,8 @@
 
   // Loop transforms on the ideal graph.  Range Check Elimination,
   // peeling, unrolling, etc.
-  if(loop_opts_cnt > 0) {
-    debug_only( int cnt = 0; );
-    while(major_progress() && (loop_opts_cnt > 0)) {
-      TracePhase tp("idealLoop", &timers[_t_idealLoop]);
-      assert( cnt++ < 40, "infinite cycle in loop optimization" );
-      PhaseIdealLoop ideal_loop( igvn, true);
-      loop_opts_cnt--;
-      if (major_progress()) print_method(PHASE_PHASEIDEALLOOP_ITERATIONS, 2);
-      if (failing())  return;
-    }
+  if (!optimize_loops(loop_opts_cnt, igvn, LoopOptsDefault)) {
+    return;
   }
 
 #if INCLUDE_ZGC
@@ -2383,6 +2393,15 @@
     }
   }
 
+  print_method(PHASE_BEFORE_BARRIER_EXPAND, 2);
+
+#if INCLUDE_SHENANDOAHGC
+  if (UseShenandoahGC && ((ShenandoahBarrierSetC2*)BarrierSet::barrier_set()->barrier_set_c2())->expand_barriers(this, igvn)) {
+    assert(failing(), "must bail out w/ explicit message");
+    return;
+  }
+#endif
+
   if (opaque4_count() > 0) {
     C->remove_opaque4_nodes(igvn);
     igvn.optimize();
@@ -2823,6 +2842,17 @@
   case Op_CallLeafNoFP: {
     assert (n->is_Call(), "");
     CallNode *call = n->as_Call();
+#if INCLUDE_SHENANDOAHGC
+    if (UseShenandoahGC && ShenandoahBarrierSetC2::is_shenandoah_wb_pre_call(call)) {
+      uint cnt = ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type()->domain()->cnt();
+      if (call->req() > cnt) {
+        assert(call->req() == cnt+1, "only one extra input");
+        Node* addp = call->in(cnt);
+        assert(!ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(addp), "useless address computation?");
+        call->del_req(cnt);
+      }
+    }
+#endif
     // Count call sites where the FP mode bit would have to be flipped.
     // Do not count uncommon runtime calls:
     // uncommon_trap, _complete_monitor_locking, _complete_monitor_unlocking,
@@ -3387,6 +3417,28 @@
     }
     break;
   }
+#if INCLUDE_SHENANDOAHGC
+  case Op_ShenandoahCompareAndSwapP:
+  case Op_ShenandoahCompareAndSwapN:
+  case Op_ShenandoahWeakCompareAndSwapN:
+  case Op_ShenandoahWeakCompareAndSwapP:
+  case Op_ShenandoahCompareAndExchangeP:
+  case Op_ShenandoahCompareAndExchangeN:
+#ifdef ASSERT
+    if( VerifyOptoOopOffsets ) {
+      MemNode* mem  = n->as_Mem();
+      // Check to see if address types have grounded out somehow.
+      const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
+      ciInstanceKlass *k = tp->klass()->as_instance_klass();
+      bool oop_offset_is_sane = k->contains_field_offset(tp->offset());
+      assert( !tp || oop_offset_is_sane, "" );
+    }
+#endif
+     break;
+  case Op_ShenandoahLoadReferenceBarrier:
+    assert(false, "should have been expanded already");
+    break;
+#endif
   case Op_RangeCheck: {
     RangeCheckNode* rc = n->as_RangeCheck();
     Node* iff = new IfNode(rc->in(0), rc->in(1), rc->_prob, rc->_fcnt);
@@ -3823,10 +3875,18 @@
 // Currently supported:
 // - G1 pre-barriers (see GraphKit::g1_write_barrier_pre())
 void Compile::verify_barriers() {
-#if INCLUDE_G1GC
-  if (UseG1GC) {
+#if INCLUDE_G1GC || INCLUDE_SHENANDOAHGC
+  if (UseG1GC || UseShenandoahGC) {
     // Verify G1 pre-barriers
+
+#if INCLUDE_G1GC && INCLUDE_SHENANDOAHGC
+    const int marking_offset = in_bytes(UseG1GC ? G1ThreadLocalData::satb_mark_queue_active_offset()
+                                                : ShenandoahThreadLocalData::satb_mark_queue_active_offset());
+#elif INCLUDE_G1GC
     const int marking_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset());
+#else
+    const int marking_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_active_offset());
+#endif
 
     ResourceArea *area = Thread::current()->resource_area();
     Unique_Node_List visited(area);
--- old/src/hotspot/share/opto/compile.hpp	2020-01-17 17:14:31.909116053 +0100
+++ new/src/hotspot/share/opto/compile.hpp	2020-01-17 17:14:31.810116058 +0100
@@ -90,6 +90,16 @@
 class Node_Stack;
 struct Final_Reshape_Counts;
 
+enum LoopOptsMode {
+  LoopOptsDefault = 0,
+  LoopOptsNone = 1,
+  LoopOptsSkipSplitIf = 2,
+  LoopOptsShenandoahExpand = 3,
+  LoopOptsShenandoahPostExpand = 4,
+  LoopOptsVerify = 5,
+  LoopOptsZgcLastRound = 6
+};
+
 typedef unsigned int node_idx_t;
 class NodeCloneInfo {
  private:
@@ -1084,6 +1094,7 @@
   void inline_incrementally(PhaseIterGVN& igvn);
   void inline_string_calls(bool parse_time);
   void inline_boxing_calls(PhaseIterGVN& igvn);
+  bool optimize_loops(int& loop_opts_cnt, PhaseIterGVN& igvn, LoopOptsMode mode);
 
   // Matching, CFG layout, allocation, code generation
   PhaseCFG*         cfg()                       { return _cfg; }
--- old/src/hotspot/share/opto/escape.cpp	2020-01-17 17:14:32.509116020 +0100
+++ new/src/hotspot/share/opto/escape.cpp	2020-01-17 17:14:32.409116025 +0100
@@ -45,6 +45,9 @@
 #if INCLUDE_ZGC
 #include "gc/z/c2/zBarrierSetC2.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 ConnectionGraph::ConnectionGraph(Compile * C, PhaseIterGVN *igvn) :
   _nodes(C->comp_arena(), C->unique(), C->unique(), NULL),
@@ -512,6 +515,10 @@
     }
     case Op_CompareAndExchangeP:
     case Op_CompareAndExchangeN:
+#if INCLUDE_SHENANDOAHGC
+    case Op_ShenandoahCompareAndExchangeP:
+    case Op_ShenandoahCompareAndExchangeN:
+#endif
     case Op_GetAndSetP:
     case Op_GetAndSetN: {
       add_objload_to_connection_graph(n, delayed_worklist);
@@ -521,6 +528,12 @@
     case Op_StoreN:
     case Op_StoreNKlass:
     case Op_StorePConditional:
+#if INCLUDE_SHENANDOAHGC
+    case Op_ShenandoahWeakCompareAndSwapP:
+    case Op_ShenandoahWeakCompareAndSwapN:
+    case Op_ShenandoahCompareAndSwapP:
+    case Op_ShenandoahCompareAndSwapN:
+#endif
     case Op_WeakCompareAndSwapP:
     case Op_WeakCompareAndSwapN:
     case Op_CompareAndSwapP:
@@ -554,8 +567,8 @@
           // Pointer stores in G1 barriers looks like unsafe access.
           // Ignore such stores to be able scalar replace non-escaping
           // allocations.
-#if INCLUDE_G1GC
-          if (UseG1GC && adr->is_AddP()) {
+#if INCLUDE_G1GC || INCLUDE_SHENANDOAHGC
+          if ((UseG1GC || UseShenandoahGC) && adr->is_AddP()) {
             Node* base = get_addp_base(adr);
             if (base->Opcode() == Op_LoadP &&
                 base->in(MemNode::Address)->is_AddP()) {
@@ -563,7 +576,15 @@
               Node* tls = get_addp_base(adr);
               if (tls->Opcode() == Op_ThreadLocal) {
                 int offs = (int)igvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
-                if (offs == in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset())) {
+#if INCLUDE_G1GC && INCLUDE_SHENANDOAHGC
+                const int buf_offset = in_bytes(UseG1GC ? G1ThreadLocalData::satb_mark_queue_buffer_offset()
+                                                        : ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
+#elif INCLUDE_G1GC
+                const int buf_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset());
+#else
+                const int buf_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
+#endif
+                if (offs == buf_offset) {
                   break; // G1 pre barrier previous oop value store.
                 }
                 if (offs == in_bytes(G1ThreadLocalData::dirty_card_queue_buffer_offset())) {
@@ -600,6 +621,13 @@
       add_java_object(n, PointsToNode::ArgEscape);
       break;
     }
+#if INCLUDE_SHENANDOAHGC
+    case Op_ShenandoahEnqueueBarrier:
+      add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), delayed_worklist);
+      break;
+    case Op_ShenandoahLoadReferenceBarrier:
+      add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahLoadReferenceBarrierNode::ValueIn), delayed_worklist);
+#endif
     default:
       ; // Do nothing for nodes not related to EA.
   }
@@ -740,6 +768,14 @@
     case Op_CompareAndSwapN:
     case Op_WeakCompareAndSwapP:
     case Op_WeakCompareAndSwapN:
+#if INCLUDE_SHENANDOAHGC
+    case Op_ShenandoahCompareAndExchangeP:
+    case Op_ShenandoahCompareAndExchangeN:
+    case Op_ShenandoahCompareAndSwapP:
+    case Op_ShenandoahCompareAndSwapN:
+    case Op_ShenandoahWeakCompareAndSwapP:
+    case Op_ShenandoahWeakCompareAndSwapN:
+#endif
     case Op_GetAndSetP:
     case Op_GetAndSetN: {
       Node* adr = n->in(MemNode::Address);
@@ -753,6 +789,9 @@
       }
 #endif
       if (opcode == Op_GetAndSetP || opcode == Op_GetAndSetN ||
+#if INCLUDE_SHENANDOAHGC
+          opcode == Op_ShenandoahCompareAndExchangeN || opcode == Op_ShenandoahCompareAndExchangeP ||
+#endif
           opcode == Op_CompareAndExchangeN || opcode == Op_CompareAndExchangeP) {
         add_local_var_and_edge(n, PointsToNode::NoEscape, adr, NULL);
       }
@@ -815,6 +854,14 @@
       }
       break;
     }
+#if INCLUDE_SHENANDOAHGC
+    case Op_ShenandoahEnqueueBarrier:
+      add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), NULL);
+      break;
+    case Op_ShenandoahLoadReferenceBarrier:
+      add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahLoadReferenceBarrierNode::ValueIn), NULL);
+      break;
+#endif
     default: {
       // This method should be called only for EA specific nodes which may
       // miss some edges when they were created.
@@ -2113,6 +2160,10 @@
         // Check for unsafe oop field access
         if (n->has_out_with(Op_StoreP, Op_LoadP, Op_StoreN, Op_LoadN) ||
             n->has_out_with(Op_GetAndSetP, Op_GetAndSetN, Op_CompareAndExchangeP, Op_CompareAndExchangeN) ||
+#if INCLUDE_SHENANDOAHGC
+            n->has_out_with(Op_ShenandoahCompareAndExchangeP) || n->has_out_with(Op_ShenandoahCompareAndExchangeN) ||
+            n->has_out_with(Op_ShenandoahCompareAndSwapP, Op_ShenandoahCompareAndSwapN, Op_ShenandoahWeakCompareAndSwapP, Op_ShenandoahWeakCompareAndSwapN) ||
+#endif
             n->has_out_with(Op_CompareAndSwapP, Op_CompareAndSwapN, Op_WeakCompareAndSwapP, Op_WeakCompareAndSwapN)) {
           bt = T_OBJECT;
           (*unsafe) = true;
@@ -2378,7 +2429,8 @@
       assert(opcode == Op_ConP || opcode == Op_ThreadLocal ||
              opcode == Op_CastX2P || uncast_base->is_DecodeNarrowPtr() ||
              (uncast_base->is_Mem() && (uncast_base->bottom_type()->isa_rawptr() != NULL)) ||
-             (uncast_base->is_Proj() && uncast_base->in(0)->is_Allocate()), "sanity");
+             (uncast_base->is_Proj() && uncast_base->in(0)->is_Allocate()) ||
+             uncast_base->Opcode() == Op_ShenandoahLoadReferenceBarrier, "sanity");
     }
   }
   return base;
--- old/src/hotspot/share/opto/graphKit.cpp	2020-01-17 17:14:33.129115986 +0100
+++ new/src/hotspot/share/opto/graphKit.cpp	2020-01-17 17:14:33.029115991 +0100
@@ -43,6 +43,10 @@
 #include "opto/runtime.hpp"
 #include "runtime/deoptimization.hpp"
 #include "runtime/sharedRuntime.hpp"
+#include "utilities/macros.hpp"
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 //----------------------------GraphKit-----------------------------------------
 // Main utility constructor.
@@ -3738,6 +3742,14 @@
   if (ptr == NULL) {     // reduce dumb test in callers
     return NULL;
   }
+
+#if INCLUDE_SHENANDOAHGC
+  if (UseShenandoahGC) {
+    BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+    ptr = bs->step_over_gc_barrier(ptr);
+  }
+#endif
+
   if (ptr->is_CheckCastPP()) { // strip only one raw-to-oop cast
     ptr = ptr->in(1);
     if (ptr == NULL) return NULL;
--- old/src/hotspot/share/opto/loopTransform.cpp	2020-01-17 17:14:33.758115951 +0100
+++ new/src/hotspot/share/opto/loopTransform.cpp	2020-01-17 17:14:33.658115956 +0100
@@ -2852,6 +2852,14 @@
             ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
              (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
              (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
+#if INCLUDE_SHENANDOAHGC
+             (bol->in(1)->Opcode() == Op_ShenandoahCompareAndExchangeP ) ||
+             (bol->in(1)->Opcode() == Op_ShenandoahCompareAndExchangeN ) ||
+             (bol->in(1)->Opcode() == Op_ShenandoahWeakCompareAndSwapP ) ||
+             (bol->in(1)->Opcode() == Op_ShenandoahWeakCompareAndSwapN ) ||
+             (bol->in(1)->Opcode() == Op_ShenandoahCompareAndSwapP ) ||
+             (bol->in(1)->Opcode() == Op_ShenandoahCompareAndSwapN ) ||
+#endif
              (bol->in(1)->Opcode() == Op_CompareAndExchangeB ) ||
              (bol->in(1)->Opcode() == Op_CompareAndExchangeS ) ||
              (bol->in(1)->Opcode() == Op_CompareAndExchangeI ) ||
--- old/src/hotspot/share/opto/loopnode.cpp	2020-01-17 17:14:34.375115917 +0100
+++ new/src/hotspot/share/opto/loopnode.cpp	2020-01-17 17:14:34.280115922 +0100
@@ -40,6 +40,10 @@
 #include "opto/mulnode.hpp"
 #include "opto/rootnode.hpp"
 #include "opto/superword.hpp"
+#include "utilities/macros.hpp"
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 //=============================================================================
 //------------------------------is_loop_iv-------------------------------------
@@ -2713,7 +2717,12 @@
 //----------------------------build_and_optimize-------------------------------
 // Create a PhaseLoop.  Build the ideal Loop tree.  Map each Ideal Node to
 // its corresponding LoopNode.  If 'optimize' is true, do some loop cleanups.
-void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool skip_loop_opts, bool last_round) {
+void PhaseIdealLoop::build_and_optimize(LoopOptsMode mode) {
+  bool do_split_ifs = (mode == LoopOptsDefault || mode == LoopOptsZgcLastRound);
+  bool skip_loop_opts = (mode == LoopOptsNone) ;
+  bool shenandoah_opts = (mode == LoopOptsShenandoahExpand ||
+                          mode == LoopOptsShenandoahPostExpand);
+
   ResourceMark rm;
 
   int old_progress = C->major_progress();
@@ -2777,7 +2786,7 @@
   }
 
   // Nothing to do, so get out
-  bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
+  bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only && !shenandoah_opts;
   bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
   if (stop_early && !do_expensive_nodes) {
     _igvn.optimize();           // Cleanup NeverBranches
@@ -2856,8 +2865,9 @@
 
   // Given early legal placement, try finding counted loops.  This placement
   // is good enough to discover most loop invariants.
-  if( !_verify_me && !_verify_only )
-    _ltree_root->counted_loop( this );
+  if (!_verify_me && !_verify_only && !shenandoah_opts) {
+    _ltree_root->counted_loop(this);
+  }
 
   // Find latest loop placement.  Find ideal loop placement.
   visited.Clear();
@@ -2928,6 +2938,16 @@
     return;
   }
 
+#if INCLUDE_SHENANDOAHGC
+  if (UseShenandoahGC && ((ShenandoahBarrierSetC2*) BarrierSet::barrier_set()->barrier_set_c2())->optimize_loops(this, mode, visited, nstack, worklist)) {
+    _igvn.optimize();
+    if (C->log() != NULL) {
+      log_loop_tree(_ltree_root, _ltree_root, C->log());
+    }
+    return;
+  }
+#endif
+
   if (ReassociateInvariants) {
     // Reassociate invariants and prep for split_thru_phi
     for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
@@ -2955,9 +2975,9 @@
   // that require basic-block info (like cloning through Phi's)
   if( SplitIfBlocks && do_split_ifs ) {
     visited.Clear();
-    split_if_with_blocks( visited, nstack, last_round );
+    split_if_with_blocks( visited, nstack, mode == LoopOptsZgcLastRound );
     NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
-    if (last_round) {
+    if (mode == LoopOptsZgcLastRound) {
       C->set_major_progress();
     }
   }
@@ -3958,7 +3978,8 @@
     }
     while(worklist.size() != 0 && LCA != early) {
       Node* s = worklist.pop();
-      if (s->is_Load() || s->Opcode() == Op_SafePoint) {
+      if (s->is_Load() || s->is_ShenandoahBarrier() || s->Opcode() == Op_SafePoint ||
+          (UseShenandoahGC && s->is_CallStaticJava() && s->as_CallStaticJava()->uncommon_trap_request() != 0)) {
         continue;
       } else if (s->is_MergeMem()) {
         for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
@@ -4146,7 +4167,9 @@
   }
   IdealLoopTree* loop = get_loop(least);
   Node* head = loop->_head;
-  if (head->is_OuterStripMinedLoop()) {
+  if (head->is_OuterStripMinedLoop() &&
+      // Verification can't be applied to fully built strip mined loops
+      head->as_Loop()->outer_loop_end()->in(1)->find_int_con(-1) == 0) {
     Node* sfpt = head->as_Loop()->outer_safepoint();
     ResourceMark rm;
     Unique_Node_List wq;
@@ -4226,6 +4249,9 @@
     case Op_HasNegatives:
       pinned = false;
     }
+    if (UseShenandoahGC && n->is_CMove()) {
+      pinned = false;
+    }
     if( pinned ) {
       IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
       if( !chosen_loop->_child )       // Inner loop?
@@ -4490,6 +4516,7 @@
     }
   }
 }
+#endif
 
 // Collect a R-P-O for the whole CFG.
 // Result list is in post-order (scan backwards for RPO)
@@ -4512,7 +4539,6 @@
     }
   }
 }
-#endif
 
 
 //=============================================================================
--- old/src/hotspot/share/opto/loopnode.hpp	2020-01-17 17:14:35.013115882 +0100
+++ new/src/hotspot/share/opto/loopnode.hpp	2020-01-17 17:14:34.913115887 +0100
@@ -925,11 +925,11 @@
     _dom_lca_tags(arena()), // Thread::resource_area
     _verify_me(NULL),
     _verify_only(true) {
-    build_and_optimize(false, false);
+    build_and_optimize(LoopOptsVerify);
   }
 
   // build the loop tree and perform any requested optimizations
-  void build_and_optimize(bool do_split_if, bool skip_loop_opts, bool last_round = false);
+  void build_and_optimize(LoopOptsMode mode);
 
   // Dominators for the sea of nodes
   void Dominators();
@@ -939,13 +939,13 @@
   Node *dom_lca_internal( Node *n1, Node *n2 ) const;
 
   // Compute the Ideal Node to Loop mapping
-  PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool skip_loop_opts = false, bool last_round = false) :
+  PhaseIdealLoop( PhaseIterGVN &igvn, LoopOptsMode mode) :
     PhaseTransform(Ideal_Loop),
     _igvn(igvn),
     _dom_lca_tags(arena()), // Thread::resource_area
     _verify_me(NULL),
     _verify_only(false) {
-    build_and_optimize(do_split_ifs, skip_loop_opts, last_round);
+      build_and_optimize(mode);
   }
 
   // Verify that verify_me made the same decisions as a fresh run.
@@ -955,7 +955,7 @@
     _dom_lca_tags(arena()), // Thread::resource_area
     _verify_me(verify_me),
     _verify_only(false) {
-    build_and_optimize(false, false);
+    build_and_optimize(LoopOptsVerify);
   }
 
   // Build and verify the loop tree without modifying the graph.  This
@@ -1291,8 +1291,10 @@
   Node *place_near_use( Node *useblock ) const;
   Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
   void try_move_store_after_loop(Node* n);
+public:
   bool identical_backtoback_ifs(Node *n);
   bool can_split_if(Node *n_ctrl);
+private:
 
   bool _created_loop_node;
 public:
@@ -1307,7 +1309,6 @@
 #ifndef PRODUCT
   void dump( ) const;
   void dump( IdealLoopTree *loop, uint rpo_idx, Node_List &rpo_list ) const;
-  void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
   void verify() const;          // Major slow  :-)
   void verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const;
   IdealLoopTree *get_loop_idx(Node* n) const {
@@ -1319,6 +1320,9 @@
   static int _loop_invokes;     // Count of PhaseIdealLoop invokes
   static int _loop_work;        // Sum of PhaseIdealLoop x _unique
 #endif
+  void rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const;
+
+  PhaseIterGVN& igvn() { return _igvn; }
 };
 
 // This kit may be used for making of a reserved copy of a loop before this loop
--- old/src/hotspot/share/opto/macro.cpp	2020-01-17 17:14:35.607115849 +0100
+++ new/src/hotspot/share/opto/macro.cpp	2020-01-17 17:14:35.508115854 +0100
@@ -47,9 +47,13 @@
 #include "opto/subnode.hpp"
 #include "opto/type.hpp"
 #include "runtime/sharedRuntime.hpp"
+#include "utilities/macros.hpp"
 #if INCLUDE_G1GC
 #include "gc/g1/g1ThreadLocalData.hpp"
 #endif // INCLUDE_G1GC
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 
 //
@@ -458,7 +462,14 @@
       if (val == mem) {
         values.at_put(j, mem);
       } else if (val->is_Store()) {
-        values.at_put(j, val->in(MemNode::ValueIn));
+        Node* n = val->in(MemNode::ValueIn);
+#if INCLUDE_SHENANDOAHGC
+        if (UseShenandoahGC) {
+          BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+          n = bs->step_over_gc_barrier(n);
+        }
+#endif
+        values.at_put(j, n);
       } else if(val->is_Proj() && val->in(0) == alloc) {
         values.at_put(j, _igvn.zerocon(ft));
       } else if (val->is_Phi()) {
@@ -569,7 +580,14 @@
       // hit a sentinel, return appropriate 0 value
       return _igvn.zerocon(ft);
     } else if (mem->is_Store()) {
-      return mem->in(MemNode::ValueIn);
+      Node* n = mem->in(MemNode::ValueIn);
+#if INCLUDE_SHENANDOAHGC
+      if (UseShenandoahGC) {
+        BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+        n = bs->step_over_gc_barrier(n);
+      }
+#endif
+      return n;
     } else if (mem->is_Phi()) {
       // attempt to produce a Phi reflecting the values on the input paths of the Phi
       Node_Stack value_phis(a, 8);
@@ -646,6 +664,7 @@
                                    k < kmax && can_eliminate; k++) {
           Node* n = use->fast_out(k);
           if (!n->is_Store() && n->Opcode() != Op_CastP2X &&
+              SHENANDOAHGC_ONLY((!UseShenandoahGC || !ShenandoahBarrierSetC2::is_shenandoah_wb_pre_call(n)) &&)
               !(n->is_ArrayCopy() &&
                 n->as_ArrayCopy()->is_clonebasic() &&
                 n->in(ArrayCopyNode::Dest) == use)) {
--- old/src/hotspot/share/opto/macroArrayCopy.cpp	2020-01-17 17:14:36.217115815 +0100
+++ new/src/hotspot/share/opto/macroArrayCopy.cpp	2020-01-17 17:14:36.117115821 +0100
@@ -31,6 +31,10 @@
 #include "opto/macro.hpp"
 #include "opto/runtime.hpp"
 #include "utilities/align.hpp"
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#include "gc/shenandoah/shenandoahRuntime.hpp"
+#endif
 
 
 void PhaseMacroExpand::insert_mem_bar(Node** ctrl, Node** mem, int opcode, Node* precedent) {
@@ -552,7 +556,7 @@
     // At this point we know we do not need type checks on oop stores.
 
     BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
-    if (alloc != NULL && !bs->array_copy_requires_gc_barriers(copy_type)) {
+    if (alloc != NULL && !bs->array_copy_requires_gc_barriers(copy_type) && !UseShenandoahGC) {
       // If we do not need gc barriers, copy using the jint or jlong stub.
       copy_type = LP64_ONLY(UseCompressedOops ? T_INT : T_LONG) NOT_LP64(T_INT);
       assert(type2aelembytes(basic_elem_type) == type2aelembytes(copy_type),
--- old/src/hotspot/share/opto/matcher.cpp	2020-01-17 17:14:36.808115783 +0100
+++ new/src/hotspot/share/opto/matcher.cpp	2020-01-17 17:14:36.706115788 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2254,6 +2254,14 @@
       case Op_StorePConditional:
       case Op_StoreIConditional:
       case Op_StoreLConditional:
+#if INCLUDE_SHENANDOAHGC
+      case Op_ShenandoahCompareAndExchangeP:
+      case Op_ShenandoahCompareAndExchangeN:
+      case Op_ShenandoahWeakCompareAndSwapP:
+      case Op_ShenandoahWeakCompareAndSwapN:
+      case Op_ShenandoahCompareAndSwapP:
+      case Op_ShenandoahCompareAndSwapN:
+#endif
       case Op_CompareAndExchangeB:
       case Op_CompareAndExchangeS:
       case Op_CompareAndExchangeI:
@@ -2497,6 +2505,14 @@
     // that a monitor exit operation contains a serializing instruction.
 
     if (xop == Op_MemBarVolatile ||
+#if INCLUDE_SHENANDOAHGC
+        xop == Op_ShenandoahCompareAndExchangeP ||
+        xop == Op_ShenandoahCompareAndExchangeN ||
+        xop == Op_ShenandoahWeakCompareAndSwapP ||
+        xop == Op_ShenandoahWeakCompareAndSwapN ||
+        xop == Op_ShenandoahCompareAndSwapN ||
+        xop == Op_ShenandoahCompareAndSwapP ||
+#endif
         xop == Op_CompareAndExchangeB ||
         xop == Op_CompareAndExchangeS ||
         xop == Op_CompareAndExchangeI ||
--- old/src/hotspot/share/opto/memnode.cpp	2020-01-17 17:14:37.423115749 +0100
+++ new/src/hotspot/share/opto/memnode.cpp	2020-01-17 17:14:37.322115755 +0100
@@ -52,6 +52,9 @@
 #if INCLUDE_ZGC
 #include "gc/z/c2/zBarrierSetC2.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 // Portions of code courtesy of Clifford Click
 
@@ -1112,6 +1115,11 @@
         (tp != NULL) && tp->is_ptr_to_boxed_value()) {
       intptr_t ignore = 0;
       Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
+#if INCLUDE_SHENANDOAHGC
+      if (UseShenandoahGC) {
+        base = ((ShenandoahBarrierSetC2*) BarrierSet::barrier_set()->barrier_set_c2())->step_over_gc_barrier(base);
+      }
+#endif
       if (base != NULL && base->is_Proj() &&
           base->as_Proj()->_con == TypeFunc::Parms &&
           base->in(0)->is_CallStaticJava() &&
--- old/src/hotspot/share/opto/mulnode.cpp	2020-01-17 17:14:38.056115714 +0100
+++ new/src/hotspot/share/opto/mulnode.cpp	2020-01-17 17:14:37.957115720 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -31,6 +31,10 @@
 #include "opto/mulnode.hpp"
 #include "opto/phaseX.hpp"
 #include "opto/subnode.hpp"
+#include "utilities/macros.hpp"
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
+#endif
 
 // Portions of code courtesy of Clifford Click
 
@@ -474,6 +478,15 @@
   Node *load = in(1);
   uint lop = load->Opcode();
 
+#if INCLUDE_SHENANDOAHGC
+  if (UseShenandoahGC && ShenandoahBarrierC2Support::is_gc_state_load(load)) {
+    // Do not touch the load+mask, we would match the whole sequence exactly.
+    // Converting the load to LoadUB/LoadUS would mismatch and waste a register
+    // on the barrier fastpath.
+    return NULL;
+  }
+#endif
+
   // Masking bits off of a Character?  Hi bits are already zero.
   if( lop == Op_LoadUS &&
       (mask & 0xFFFF0000) )     // Can we make a smaller mask?
--- old/src/hotspot/share/opto/node.hpp	2020-01-17 17:14:38.650115681 +0100
+++ new/src/hotspot/share/opto/node.hpp	2020-01-17 17:14:38.552115687 +0100
@@ -143,6 +143,7 @@
 class RootNode;
 class SafePointNode;
 class SafePointScalarObjectNode;
+class ShenandoahBarrierNode;
 class StartNode;
 class State;
 class StoreNode;
@@ -678,6 +679,7 @@
       DEFINE_CLASS_ID(EncodeNarrowPtr, Type, 6)
         DEFINE_CLASS_ID(EncodeP, EncodeNarrowPtr, 0)
         DEFINE_CLASS_ID(EncodePKlass, EncodeNarrowPtr, 1)
+      DEFINE_CLASS_ID(ShenandoahBarrier, Type, 7)
 
     DEFINE_CLASS_ID(Proj,  Node, 3)
       DEFINE_CLASS_ID(CatchProj, Proj, 0)
@@ -877,6 +879,7 @@
   DEFINE_CLASS_QUERY(Root)
   DEFINE_CLASS_QUERY(SafePoint)
   DEFINE_CLASS_QUERY(SafePointScalarObject)
+  DEFINE_CLASS_QUERY(ShenandoahBarrier)
   DEFINE_CLASS_QUERY(Start)
   DEFINE_CLASS_QUERY(Store)
   DEFINE_CLASS_QUERY(Sub)
--- old/src/hotspot/share/opto/phaseX.cpp	2020-01-17 17:14:39.249115648 +0100
+++ new/src/hotspot/share/opto/phaseX.cpp	2020-01-17 17:14:39.145115654 +0100
@@ -2106,6 +2106,10 @@
     default:
       break;
     }
+    if (UseShenandoahGC) {
+      // TODO: Should we call this for ZGC as well?
+      BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn->_worklist, old);
+    }
   }
 
 }
--- old/src/hotspot/share/opto/phasetype.hpp	2020-01-17 17:14:39.861115615 +0100
+++ new/src/hotspot/share/opto/phasetype.hpp	2020-01-17 17:14:39.762115620 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -52,6 +52,7 @@
   PHASE_MATCHING,
   PHASE_INCREMENTAL_INLINE,
   PHASE_INCREMENTAL_BOXING_INLINE,
+  PHASE_BEFORE_BARRIER_EXPAND,
   PHASE_BEFORE_MACRO_EXPANSION,
   PHASE_END,
   PHASE_FAILURE,
@@ -89,6 +90,7 @@
       case PHASE_MATCHING:                   return "After matching";
       case PHASE_INCREMENTAL_INLINE:         return "Incremental Inline";
       case PHASE_INCREMENTAL_BOXING_INLINE:  return "Incremental Boxing Inline";
+      case PHASE_BEFORE_BARRIER_EXPAND:      return "Before Barrier Expand";
       case PHASE_BEFORE_MACRO_EXPANSION:     return "Before macro expansion";
       case PHASE_END:                        return "End";
       case PHASE_FAILURE:                    return "Failure";
--- old/src/hotspot/share/opto/type.hpp	2020-01-17 17:14:40.437115583 +0100
+++ new/src/hotspot/share/opto/type.hpp	2020-01-17 17:14:40.338115588 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1770,6 +1770,8 @@
 // UseOptoBiasInlining
 #define XorXNode     XorLNode
 #define StoreXConditionalNode StoreLConditionalNode
+#define LoadXNode    LoadLNode
+#define StoreXNode   StoreLNode
 // Opcodes
 #define Op_LShiftX   Op_LShiftL
 #define Op_AndX      Op_AndL
@@ -1815,6 +1817,8 @@
 // UseOptoBiasInlining
 #define XorXNode     XorINode
 #define StoreXConditionalNode StoreIConditionalNode
+#define LoadXNode    LoadINode
+#define StoreXNode   StoreINode
 // Opcodes
 #define Op_LShiftX   Op_LShiftI
 #define Op_AndX      Op_AndI
--- old/src/hotspot/share/runtime/mutexLocker.cpp	2020-01-17 17:14:41.038115550 +0100
+++ new/src/hotspot/share/runtime/mutexLocker.cpp	2020-01-17 17:14:40.938115555 +0100
@@ -216,6 +216,14 @@
     def(MarkStackFreeList_lock     , PaddedMutex  , leaf     ,   true,  Monitor::_safepoint_check_never);
     def(MarkStackChunkList_lock    , PaddedMutex  , leaf     ,   true,  Monitor::_safepoint_check_never);
   }
+  if (UseShenandoahGC) {
+    def(SATB_Q_FL_lock             , PaddedMutex  , access,      true,  Monitor::_safepoint_check_never);
+    def(SATB_Q_CBL_mon             , PaddedMonitor, access,      true,  Monitor::_safepoint_check_never);
+    def(Shared_SATB_Q_lock         , PaddedMutex  , access + 1,  true,  Monitor::_safepoint_check_never);
+
+    def(StringDedupQueue_lock      , PaddedMonitor, leaf,        true,  Monitor::_safepoint_check_never);
+    def(StringDedupTable_lock      , PaddedMutex  , leaf,        true,  Monitor::_safepoint_check_never);
+  }
   def(ParGCRareEvent_lock          , PaddedMutex  , leaf     ,   true,  Monitor::_safepoint_check_sometimes);
   def(DerivedPointerTableGC_lock   , PaddedMutex  , leaf,        true,  Monitor::_safepoint_check_never);
   def(CGCPhaseManager_lock         , PaddedMonitor, leaf,        false, Monitor::_safepoint_check_sometimes);
--- old/src/hotspot/share/runtime/sharedRuntime.cpp	2020-01-17 17:14:41.623115518 +0100
+++ new/src/hotspot/share/runtime/sharedRuntime.cpp	2020-01-17 17:14:41.522115523 +0100
@@ -2880,6 +2880,24 @@
   GCLocker::unlock_critical(thread);
 JRT_END
 
+JRT_LEAF(oopDesc*, SharedRuntime::pin_object(JavaThread* thread, oopDesc* obj))
+  assert(Universe::heap()->supports_object_pinning(), "Why we here?");
+  assert(UseShenandoahGC, "only supported in Shenandoah for now");
+  assert(obj != NULL, "Should not be null");
+  oop o(obj);
+  o = Universe::heap()->pin_object(thread, o);
+  assert(o != NULL, "Should not be null");
+  return o;
+JRT_END
+
+JRT_LEAF(void, SharedRuntime::unpin_object(JavaThread* thread, oopDesc* obj))
+  assert(Universe::heap()->supports_object_pinning(), "Why we here?");
+  assert(UseShenandoahGC, "only supported in Shenandoah for now");
+  assert(obj != NULL, "Should not be null");
+  oop o(obj);
+  Universe::heap()->unpin_object(thread, o);
+JRT_END
+
 // -------------------------------------------------------------------------
 // Java-Java calling convention
 // (what you use when Java calls Java)
--- old/src/hotspot/share/runtime/sharedRuntime.hpp	2020-01-17 17:14:42.235115484 +0100
+++ new/src/hotspot/share/runtime/sharedRuntime.hpp	2020-01-17 17:14:42.137115489 +0100
@@ -487,6 +487,10 @@
   // Block before entering a JNI critical method
   static void block_for_jni_critical(JavaThread* thread);
 
+  // Pin/Unpin object
+  static oopDesc* pin_object(JavaThread* thread, oopDesc* obj);
+  static void unpin_object(JavaThread* thread, oopDesc* obj);
+
   // A compiled caller has just called the interpreter, but compiled code
   // exists.  Patch the caller so he no longer calls into the interpreter.
   static void fixup_callers_callsite(Method* moop, address ret_pc);
--- old/src/hotspot/share/runtime/stackValue.cpp	2020-01-17 17:14:42.822115451 +0100
+++ new/src/hotspot/share/runtime/stackValue.cpp	2020-01-17 17:14:42.722115457 +0100
@@ -32,6 +32,9 @@
 #if INCLUDE_ZGC
 #include "gc/z/zBarrier.inline.hpp"
 #endif
+#if INCLUDE_SHENANDOAHGC
+#include "gc/shenandoah/shenandoahBarrierSet.hpp"
+#endif
 
 StackValue* StackValue::create_stack_value(const frame* fr, const RegisterMap* reg_map, ScopeValue* sv) {
   if (sv->is_location()) {
@@ -106,8 +109,15 @@
       } else {
         value.noop = *(narrowOop*) value_addr;
       }
-      // Decode narrowoop and wrap a handle around the oop
-      Handle h(Thread::current(), CompressedOops::decode(value.noop));
+      // Decode narrowoop
+      oop val = CompressedOops::decode(value.noop);
+      // Deoptimization must make sure all oops have passed load barriers
+#if INCLUDE_SHENANDOAHGC
+      if (UseShenandoahGC) {
+        val = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(val);
+      }
+#endif
+      Handle h(Thread::current(), val); // Wrap a handle around the oop
       return new StackValue(h);
     }
 #endif
@@ -122,13 +132,17 @@
          val = (oop)NULL;
       }
 #endif
+      // Deoptimization must make sure all oops have passed load barriers
 #if INCLUDE_ZGC
-      // Deoptimization must make sure all oop have passed load barrier
       if (UseZGC) {
         val = ZBarrier::load_barrier_on_oop_field_preloaded((oop*)value_addr, val);
       }
 #endif
-
+#if INCLUDE_SHENANDOAHGC
+      if (UseShenandoahGC) {
+        val = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(val);
+      }
+#endif
       Handle h(Thread::current(), val); // Wrap a handle around the oop
       return new StackValue(h);
     }
--- old/src/hotspot/share/runtime/vmOperations.hpp	2020-01-17 17:14:43.398115420 +0100
+++ new/src/hotspot/share/runtime/vmOperations.hpp	2020-01-17 17:14:43.299115425 +0100
@@ -99,6 +99,15 @@
   template(HeapIterateOperation)                  \
   template(ReportJavaOutOfMemory)                 \
   template(JFRCheckpoint)                         \
+  template(ShenandoahFullGC)                      \
+  template(ShenandoahInitMark)                    \
+  template(ShenandoahFinalMarkStartEvac)          \
+  template(ShenandoahFinalEvac)                   \
+  template(ShenandoahInitTraversalGC)             \
+  template(ShenandoahFinalTraversalGC)            \
+  template(ShenandoahInitUpdateRefs)              \
+  template(ShenandoahFinalUpdateRefs)             \
+  template(ShenandoahDegeneratedGC)               \
   template(Exit)                                  \
   template(LinuxDllLoad)                          \
   template(RotateGCLog)                           \
--- old/src/hotspot/share/utilities/globalDefinitions.hpp	2020-01-17 17:14:43.982115388 +0100
+++ new/src/hotspot/share/utilities/globalDefinitions.hpp	2020-01-17 17:14:43.882115393 +0100
@@ -69,6 +69,7 @@
 #define UINT64_FORMAT_X        "%" PRIx64
 #define INT64_FORMAT_W(width)  "%" #width PRId64
 #define UINT64_FORMAT_W(width) "%" #width PRIu64
+#define UINT64_FORMAT_X_W(width) "%" #width PRIx64
 
 #define PTR64_FORMAT           "0x%016" PRIx64
 
--- old/src/hotspot/share/utilities/macros.hpp	2020-01-17 17:14:44.575115355 +0100
+++ new/src/hotspot/share/utilities/macros.hpp	2020-01-17 17:14:44.475115360 +0100
@@ -221,6 +221,24 @@
 #define NOT_SERIALGC_RETURN_(code) { return code; }
 #endif // INCLUDE_SERIALGC
 
+#ifndef INCLUDE_SHENANDOAHGC
+#define INCLUDE_SHENANDOAHGC 1
+#endif // INCLUDE_SHENANDOAHGC
+
+#if INCLUDE_SHENANDOAHGC
+#define SHENANDOAHGC_ONLY(x) x
+#define SHENANDOAHGC_ONLY_ARG(arg) arg,
+#define NOT_SHENANDOAHGC(x)
+#define NOT_SHENANDOAHGC_RETURN        /* next token must be ; */
+#define NOT_SHENANDOAHGC_RETURN_(code) /* next token must be ; */
+#else
+#define SHENANDOAHGC_ONLY(x)
+#define SHENANDOAHGC_ONLY_ARG(arg)
+#define NOT_SHENANDOAHGC(x) x
+#define NOT_SHENANDOAHGC_RETURN        {}
+#define NOT_SHENANDOAHGC_RETURN_(code) { return code; }
+#endif // INCLUDE_SHENANDOAHGC
+
 #ifndef INCLUDE_ZGC
 #define INCLUDE_ZGC 1
 #endif // INCLUDE_ZGC
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/HSDB.java	2020-01-17 17:14:45.149115323 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/HSDB.java	2020-01-17 17:14:45.048115329 +0100
@@ -36,6 +36,7 @@
 import sun.jvm.hotspot.gc.epsilon.*;
 import sun.jvm.hotspot.gc.parallel.*;
 import sun.jvm.hotspot.gc.shared.*;
+import sun.jvm.hotspot.gc.shenandoah.*;
 import sun.jvm.hotspot.gc.g1.*;
 import sun.jvm.hotspot.gc.z.*;
 import sun.jvm.hotspot.interpreter.*;
@@ -1113,6 +1114,10 @@
                         } else if (collHeap instanceof EpsilonHeap) {
                           anno = "Epsilon ";
                           bad = false;
+                        } else if (collHeap instanceof ShenandoahHeap) {
+                          ShenandoahHeap heap = (ShenandoahHeap) collHeap;
+                          anno = "ShenandoahHeap ";
+                          bad = false;
                         } else if (collHeap instanceof ZCollectedHeap) {
                           ZCollectedHeap heap = (ZCollectedHeap) collHeap;
                           anno = "ZHeap ";
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/CollectedHeapName.java	2020-01-17 17:14:45.746115290 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/CollectedHeapName.java	2020-01-17 17:14:45.648115296 +0100
@@ -37,6 +37,7 @@
   public static final CollectedHeapName G1 = new CollectedHeapName("G1");
   public static final CollectedHeapName EPSILON = new CollectedHeapName("Epsilon");
   public static final CollectedHeapName Z = new CollectedHeapName("Z");
+  public static final CollectedHeapName SHENANDOAH = new CollectedHeapName("Shenandoah");
 
   public String toString() {
     return name;
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/GCCause.java	2020-01-17 17:14:46.322115259 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/GCCause.java	2020-01-17 17:14:46.222115264 +0100
@@ -67,6 +67,12 @@
   _z_allocation_stall ("Allocation Stall"),
   _z_proactive ("Proactive"),
 
+  _shenandoah_allocation_failure_evac ("Allocation Failure During Evacuation"),
+  _shenandoah_stop_vm ("Stopping VM"),
+  _shenandoah_concurrent_gc ("Concurrent GC"),
+  _shenandoah_traversal_gc ("Traversal GC"),
+  _shenandoah_upgrade_to_full_gc ("Upgrade To Full GC"),
+
   _last_gc_cause ("ILLEGAL VALUE - last gc cause - ILLEGAL VALUE");
 
   private final String value;
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/GCName.java	2020-01-17 17:14:46.904115227 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/GCName.java	2020-01-17 17:14:46.801115232 +0100
@@ -38,6 +38,7 @@
   G1Old ("G1Old"),
   G1Full ("G1Full"),
   Z ("Z"),
+  Shenandoah ("Shenandoah"),
   NA ("N/A"),
   GCNameEndSentinel ("GCNameEndSentinel");
 
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/memory/Universe.java	2020-01-17 17:14:47.483115195 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/memory/Universe.java	2020-01-17 17:14:47.383115200 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,7 @@
 import sun.jvm.hotspot.gc.parallel.ParallelScavengeHeap;
 import sun.jvm.hotspot.gc.serial.SerialHeap;
 import sun.jvm.hotspot.gc.shared.CollectedHeap;
+import sun.jvm.hotspot.gc.shenandoah.ShenandoahHeap;
 import sun.jvm.hotspot.gc.z.ZCollectedHeap;
 import sun.jvm.hotspot.oops.Oop;
 import sun.jvm.hotspot.runtime.BasicType;
@@ -110,6 +111,7 @@
     addHeapTypeIfInDB(db, G1CollectedHeap.class);
     addHeapTypeIfInDB(db, EpsilonHeap.class);
     addHeapTypeIfInDB(db, ZCollectedHeap.class);
+    addHeapTypeIfInDB(db, ShenandoahHeap.class);
 
     mainThreadGroupField   = type.getOopField("_main_thread_group");
     systemThreadGroupField = type.getOopField("_system_thread_group");
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ObjectHeap.java	2020-01-17 17:14:48.070115162 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ObjectHeap.java	2020-01-17 17:14:47.968115168 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,7 @@
 import sun.jvm.hotspot.gc.shared.*;
 import sun.jvm.hotspot.gc.epsilon.*;
 import sun.jvm.hotspot.gc.g1.*;
+import sun.jvm.hotspot.gc.shenandoah.*;
 import sun.jvm.hotspot.gc.parallel.*;
 import sun.jvm.hotspot.memory.*;
 import sun.jvm.hotspot.runtime.*;
@@ -439,6 +440,10 @@
     } else if (heap instanceof G1CollectedHeap) {
         G1CollectedHeap g1h = (G1CollectedHeap) heap;
         g1h.heapRegionIterate(lrc);
+    } else if (heap instanceof ShenandoahHeap) {
+       // Operation (currently) not supported with Shenandoah GC. Print
+       // a warning and leave the list of live regions empty.
+       System.err.println("Warning: Operation not supported with Shenandoah GC");
     } else if (heap instanceof EpsilonHeap) {
        EpsilonHeap eh = (EpsilonHeap) heap;
        liveRegions.add(eh.space().top());
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/VMOps.java	2020-01-17 17:14:48.650115130 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/VMOps.java	2020-01-17 17:14:48.553115136 +0100
@@ -55,6 +55,7 @@
   CMS_Final_Remark,
   G1CollectFull,
   ZOperation,
+  ShenandoahOperation,
   G1CollectForAllocation,
   G1IncCollectionPause,
   EnableBiasedLocking,
--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/tools/HeapSummary.java	2020-01-17 17:14:49.230115098 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/tools/HeapSummary.java	2020-01-17 17:14:49.130115104 +0100
@@ -29,6 +29,7 @@
 import sun.jvm.hotspot.gc.g1.*;
 import sun.jvm.hotspot.gc.parallel.*;
 import sun.jvm.hotspot.gc.serial.*;
+import sun.jvm.hotspot.gc.shenandoah.*;
 import sun.jvm.hotspot.gc.shared.*;
 import sun.jvm.hotspot.gc.z.*;
 import sun.jvm.hotspot.debugger.JVMDebugger;
@@ -83,7 +84,11 @@
       printValMB("MetaspaceSize            = ", getFlagValue("MetaspaceSize", flagMap));
       printValMB("CompressedClassSpaceSize = ", getFlagValue("CompressedClassSpaceSize", flagMap));
       printValMB("MaxMetaspaceSize         = ", getFlagValue("MaxMetaspaceSize", flagMap));
-      printValMB("G1HeapRegionSize         = ", HeapRegion.grainBytes());
+      if (heap instanceof ShenandoahHeap) {
+         printValMB("ShenandoahRegionSize     = ", ShenandoahHeapRegion.regionSizeBytes());
+      } else {
+         printValMB("G1HeapRegionSize         = ", HeapRegion.grainBytes());
+      }
 
       System.out.println();
       System.out.println("Heap Usage:");
@@ -126,6 +131,14 @@
          printValMB("used     = ", oldGen.used());
          printValMB("free     = ", oldFree);
          System.out.println(alignment + (double)oldGen.used() * 100.0 / oldGen.capacity() + "% used");
+      } else if (heap instanceof ShenandoahHeap) {
+         ShenandoahHeap sh = (ShenandoahHeap) heap;
+         long num_regions = sh.numOfRegions();
+         System.out.println("Shenandoah Heap:");
+         System.out.println("   regions   = " + num_regions);
+         printValMB("capacity  = ", num_regions * ShenandoahHeapRegion.regionSizeBytes());
+         printValMB("used      = ", sh.used());
+         printValMB("committed = ", sh.committed());
       } else if (heap instanceof EpsilonHeap) {
          EpsilonHeap eh = (EpsilonHeap) heap;
          printSpace(eh.space());
@@ -181,6 +194,14 @@
            l = getFlagValue("ParallelGCThreads", flagMap);
            System.out.println("with " + l + " thread(s)");
            return;
+       }
+
+       l = getFlagValue("UseShenandoahGC", flagMap);
+       if (l == 1L) {
+           System.out.print("Shenandoah GC ");
+           l = getFlagValue("ParallelGCThreads", flagMap);
+           System.out.println("with " + l + " thread(s)");
+           return;
        }
 
        System.out.println("Mark Sweep Compact GC");
--- old/src/jdk.jfr/share/conf/jfr/default.jfc	2020-01-17 17:14:49.811115066 +0100
+++ new/src/jdk.jfr/share/conf/jfr/default.jfc	2020-01-17 17:14:49.709115072 +0100
@@ -420,6 +420,15 @@
       <setting name="enabled" control="gc-enabled-all">false</setting>
     </event>
 
+    <event name="jdk.ShenandoahHeapRegionInformation">
+      <setting name="enabled" control="gc-enabled-all">false</setting>
+      <setting name="period">everyChunk</setting>
+    </event>
+
+    <event name="jdk.ShenandoahHeapRegionStateChange">
+      <setting name="enabled" control="gc-enabled-all">false</setting>
+    </event>
+
     <event name="jdk.OldObjectSample">
       <setting name="enabled" control="memory-leak-detection-enabled">true</setting>
       <setting name="stackTrace" control="memory-leak-detection-stack-trace">false</setting>
--- old/src/jdk.jfr/share/conf/jfr/profile.jfc	2020-01-17 17:14:50.404115034 +0100
+++ new/src/jdk.jfr/share/conf/jfr/profile.jfc	2020-01-17 17:14:50.305115039 +0100
@@ -420,6 +420,15 @@
       <setting name="enabled" control="gc-enabled-all">false</setting>
     </event>
 
+    <event name="jdk.ShenandoahHeapRegionInformation">
+      <setting name="enabled" control="gc-enabled-all">false</setting>
+      <setting name="period">everyChunk</setting>
+    </event>
+
+    <event name="jdk.ShenandoahHeapRegionStateChange">
+      <setting name="enabled" control="gc-enabled-all">false</setting>
+    </event>
+
     <event name="jdk.OldObjectSample">
       <setting name="enabled" control="memory-leak-detection-enabled">true</setting>
       <setting name="stackTrace" control="memory-leak-detection-stack-trace">true</setting>
--- old/test/hotspot/jtreg/TEST.ROOT	2020-01-17 17:14:50.987115002 +0100
+++ new/test/hotspot/jtreg/TEST.ROOT	2020-01-17 17:14:50.889115007 +0100
@@ -48,6 +48,7 @@
     vm.gc.Serial \
     vm.gc.Parallel \
     vm.gc.ConcMarkSweep \
+    vm.gc.Shenandoah \
     vm.gc.Epsilon \
     vm.gc.Z \
     vm.jvmci \
--- old/test/hotspot/jtreg/TEST.groups	2020-01-17 17:14:51.564114970 +0100
+++ new/test/hotspot/jtreg/TEST.groups	2020-01-17 17:14:51.464114975 +0100
@@ -175,7 +175,8 @@
   :tier1_gc_1 \
   :tier1_gc_2 \
   :tier1_gc_gcold \
-  :tier1_gc_gcbasher
+  :tier1_gc_gcbasher \
+  :tier1_gc_shenandoah
 
 hotspot_not_fast_gc = \
   :hotspot_gc \
@@ -195,7 +196,8 @@
   -gc/stress \
   -gc/survivorAlignment/TestPromotionFromSurvivorToTenuredAfterMinorGC.java \
   -gc/cms/TestMBeanCMS.java \
-  -gc/metaspace/CompressedClassSpaceSizeInJmapHeap.java
+  -gc/metaspace/CompressedClassSpaceSizeInJmapHeap.java \
+  -gc/shenandoah
 
 tier1_gc_gcold = \
   gc/stress/gcold/TestGCOldWithG1.java \
@@ -208,6 +210,51 @@
   gc/stress/gcbasher/TestGCBasherWithCMS.java \
   gc/stress/gcbasher/TestGCBasherWithSerial.java \
   gc/stress/gcbasher/TestGCBasherWithParallel.java
+  
+tier1_gc_shenandoah = \
+  gc/shenandoah/options/ \
+  gc/shenandoah/compiler/ \
+  gc/shenandoah/mxbeans/ \
+  gc/shenandoah/TestSmallHeap.java \
+  gc/shenandoah/oom/
+
+tier2_gc_shenandoah = \
+  runtime/MemberName/MemberNameLeak.java \
+  runtime/CompressedOops/UseCompressedOops.java \
+  gc/TestHumongousReferenceObject.java \
+  gc/TestSystemGC.java \
+  gc/arguments/TestDisableDefaultGC.java \
+  gc/arguments/TestUseCompressedOopsErgo.java \
+  gc/arguments/TestAlignmentToUseLargePages.java \
+  gc/class_unloading/TestClassUnloadingDisabled.java \
+  gc/ergonomics/TestInitialGCThreadLogging.java \
+  gc/ergonomics/TestDynamicNumberOfGCThreads.java \
+  gc/logging/TestGCId.java \
+  gc/metaspace/TestMetaspacePerfCounters.java \
+  gc/metaspace/TestMetaspacePerfCounters.java \
+  gc/startup_warnings/TestShenandoah.java \
+  gc/TestFullGCALot.java \
+  gc/logging/TestUnifiedLoggingSwitchStress.java \
+  runtime/Metaspace/DefineClass.java \
+  gc/shenandoah/ \
+  serviceability/sa/TestHeapDumpForInvokeDynamic.java \
+  -gc/shenandoah/TestStringDedupStress.java \
+  -gc/shenandoah/jni/CriticalNativeStress.java \
+  -:tier1_gc_shenandoah
+
+tier3_gc_shenandoah = \
+  gc/stress/gcold/TestGCOldWithShenandoah.java \
+  gc/stress/gcbasher/TestGCBasherWithShenandoah.java \
+  gc/stress/gclocker/TestGCLockerWithShenandoah.java \
+  gc/stress/systemgc/TestSystemGCWithShenandoah.java \
+  gc/shenandoah/TestStringDedupStress.java \
+  gc/shenandoah/jni/CriticalNativeStress.java \
+  -:tier2_gc_shenandoah
+
+hotspot_gc_shenandoah = \
+  :tier1_gc_shenandoah \
+  :tier2_gc_shenandoah \
+  :tier3_gc_shenandoah
 
 tier1_runtime = \
   runtime/ \
--- old/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java	2020-01-17 17:14:52.149114938 +0100
+++ new/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java	2020-01-17 17:14:52.048114943 +0100
@@ -39,7 +39,9 @@
  *                    CMS,
  *                    CMSCondMark,
  *                    Serial,
- *                    Parallel}
+ *                    Parallel,
+ *                    Shenandoah,
+ *                    ShenandoahTraversal}
  */
 
 
@@ -100,6 +102,18 @@
             procArgs[argcount - 3] = "-XX:+UseConcMarkSweepGC";
             procArgs[argcount - 2] = "-XX:+UseCondCardMark";
             break;
+        case "Shenandoah":
+            argcount = 8;
+            procArgs = new String[argcount];
+            procArgs[argcount - 2] = "-XX:+UseShenandoahGC";
+            break;
+        case "ShenandoahTraversal":
+            argcount = 10;
+            procArgs = new String[argcount];
+            procArgs[argcount - 4] = "-XX:+UseShenandoahGC";
+            procArgs[argcount - 3] = "-XX:+UnlockExperimentalVMOptions";
+            procArgs[argcount - 2] = "-XX:ShenandoahGCMode=traversal";
+            break;
         default:
             throw new RuntimeException("unexpected test type " + testType);
         }
@@ -355,6 +369,17 @@
                     "ret"
                 };
                 break;
+            case "Shenandoah":
+            case "ShenandoahTraversal":
+                 // Shenandoah generates normal object graphs for
+                 // volatile stores
+                matches = new String[] {
+                    "membar_release (elided)",
+                    "stlrw",
+                    "membar_volatile (elided)",
+                    "ret"
+                };
+                break;
             }
         } else {
             switch (testType) {
@@ -418,6 +443,20 @@
                     "ret"
                 };
                 break;
+
+            case "Shenandoah":
+            case "ShenandoahTraversal":
+                 // Shenandoah generates normal object graphs for
+                 // volatile stores
+                matches = new String[] {
+                    "membar_release",
+                    "dmb ish",
+                    "strw",
+                    "membar_volatile",
+                    "dmb ish",
+                    "ret"
+                };
+                break;
             }
         }
 
@@ -520,6 +559,17 @@
                     "ret"
                 };
                 break;
+            case "Shenandoah":
+            case "ShenandoahTraversal":
+                // For volatile CAS, Shenanodoah generates normal
+                // graphs with a shenandoah-specific cmpxchg
+                matches = new String[] {
+                    "membar_release (elided)",
+                    "cmpxchgw_acq_shenandoah",
+                    "membar_acquire (elided)",
+                    "ret"
+                };
+                break;
             }
         } else {
             switch (testType) {
@@ -762,6 +812,19 @@
                     "membar_acquire",
                     "dmb ish",
                     "ret"
+                };
+                break;
+            case "Shenandoah":
+            case "ShenandoahTraversal":
+                // For volatile CAS, Shenanodoah generates normal
+                // graphs with a shenandoah-specific cmpxchg
+                matches = new String[] {
+                    "membar_release",
+                    "dmb ish",
+                    "cmpxchgw_shenandoah",
+                    "membar_acquire",
+                    "dmb ish",
+                    "ret"
                 };
                 break;
             }
--- old/test/hotspot/jtreg/gc/TestFullGCCount.java	2020-01-17 17:14:52.742114905 +0100
+++ new/test/hotspot/jtreg/gc/TestFullGCCount.java	2020-01-17 17:14:52.643114910 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,7 +25,9 @@
  * @test TestFullGCCount.java
  * @bug 7072527
  * @summary CMS: JMM GC counters overcount in some cases
- * @requires !(vm.gc.ConcMarkSweep & vm.opt.ExplicitGCInvokesConcurrent == true)
+ * @requires !(vm.gc == "ConcMarkSweep" & vm.opt.ExplicitGCInvokesConcurrent == true)
+ * @comment Shenandoah has "ExplicitGCInvokesConcurrent" on by default
+ * @requires !(vm.gc == "Shenandoah"    & vm.opt.ExplicitGCInvokesConcurrent != false)
  * @modules java.management
  * @run main/othervm -Xlog:gc TestFullGCCount
  */
--- old/test/hotspot/jtreg/gc/TestHumongousReferenceObject.java	2020-01-17 17:14:53.323114873 +0100
+++ new/test/hotspot/jtreg/gc/TestHumongousReferenceObject.java	2020-01-17 17:14:53.221114878 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -35,6 +35,16 @@
  * @run main/othervm -XX:+EnableContended -XX:-RestrictContended -Xmx128m -XX:+UseG1GC -XX:G1HeapRegionSize=4M -XX:ContendedPaddingWidth=8192 TestHumongousReferenceObject
  * @run main/othervm -XX:+EnableContended -XX:-RestrictContended -Xmx128m -XX:+UseG1GC -XX:G1HeapRegionSize=8M -XX:ContendedPaddingWidth=8192 TestHumongousReferenceObject
  */
+
+/*
+ * @test TestHumongousReferenceObjectShenandoah
+ * @summary Test that verifies that iteration over large, plain Java objects, that potentially cross region boundaries, with references in them works.
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @bug 8151499 8153734
+ * @modules java.base/jdk.internal.vm.annotation
+ * @run main/othervm -XX:+EnableContended -XX:-RestrictContended -Xms128m -Xmx128m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahHeapRegionSize=8M -XX:ContendedPaddingWidth=8192 TestHumongousReferenceObject
+ * @run main/othervm -XX:+EnableContended -XX:-RestrictContended -Xms128m -Xmx128m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahHeapRegionSize=8M -XX:ContendedPaddingWidth=8192 -XX:+UnlockDiagnosticVMOptions -XX:+ShenandoahVerify TestHumongousReferenceObject
+ */
 public class TestHumongousReferenceObject {
 
     /*
--- old/test/hotspot/jtreg/gc/TestSystemGC.java	2020-01-17 17:14:53.904114841 +0100
+++ new/test/hotspot/jtreg/gc/TestSystemGC.java	2020-01-17 17:14:53.805114846 +0100
@@ -45,6 +45,14 @@
  * @run main/othervm -XX:+UseConcMarkSweepGC -XX:+ExplicitGCInvokesConcurrent TestSystemGC
  */
 
+/*
+ * @test TestSystemGCShenandoah
+ * @key gc
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Runs System.gc() with different flags.
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC TestSystemGC
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+ExplicitGCInvokesConcurrent TestSystemGC
+ */
 public class TestSystemGC {
   public static void main(String args[]) throws Exception {
     System.gc();
--- old/test/hotspot/jtreg/gc/arguments/TestAlignmentToUseLargePages.java	2020-01-17 17:14:54.478114809 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestAlignmentToUseLargePages.java	2020-01-17 17:14:54.380114815 +0100
@@ -48,6 +48,16 @@
  * @run main/othervm -Xms71M -Xmx91M -XX:+UseConcMarkSweepGC -XX:-UseLargePages TestAlignmentToUseLargePages
  */
 
+/**
+ * @test TestAlignmentToUseLargePagesShenandoah
+ * @key gc
+ * @bug 8024396
+ * @comment Graal does not support Shenandoah
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @run main/othervm -Xms71M -Xmx91M -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UseLargePages TestAlignmentToUseLargePages
+ * @run main/othervm -Xms71M -Xmx91M -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:-UseLargePages TestAlignmentToUseLargePages
+ */
+
 public class TestAlignmentToUseLargePages {
   public static void main(String args[]) throws Exception {
     // nothing to do
--- old/test/hotspot/jtreg/gc/arguments/TestDisableDefaultGC.java	2020-01-17 17:14:55.062114777 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestDisableDefaultGC.java	2020-01-17 17:14:54.960114783 +0100
@@ -44,6 +44,7 @@
                                                                   "-XX:-UseG1GC",
                                                                   "-XX:-UseConcMarkSweepGC",
                                                                   "-XX:+UnlockExperimentalVMOptions",
+                                                                  "-XX:-UseShenandoahGC",
                                                                   "-XX:-UseZGC",
                                                                   "-version");
         OutputAnalyzer output = new OutputAnalyzer(pb.start());
--- old/test/hotspot/jtreg/gc/arguments/TestMaxMinHeapFreeRatioFlags.java	2020-01-17 17:14:55.640114745 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestMaxMinHeapFreeRatioFlags.java	2020-01-17 17:14:55.540114751 +0100
@@ -25,7 +25,7 @@
  * @test TestMaxMinHeapFreeRatioFlags
  * @key gc
  * @summary Verify that heap size changes according to max and min heap free ratios.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/arguments/TestNewRatioFlag.java	2020-01-17 17:14:56.216114713 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestNewRatioFlag.java	2020-01-17 17:14:56.117114719 +0100
@@ -26,7 +26,7 @@
  * @key gc
  * @bug 8025166
  * @summary Verify that heap devided among generations according to NewRatio
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/arguments/TestNewSizeFlags.java	2020-01-17 17:14:56.788114682 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestNewSizeFlags.java	2020-01-17 17:14:56.695114687 +0100
@@ -26,7 +26,7 @@
  * @key gc
  * @bug 8025166
  * @summary Verify that young gen size conforms values specified by NewSize, MaxNewSize and Xmn options
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/arguments/TestShrinkHeapInSteps.java	2020-01-17 17:14:57.367114650 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestShrinkHeapInSteps.java	2020-01-17 17:14:57.267114655 +0100
@@ -25,7 +25,7 @@
  * @test TestShrinkHeapInSteps
  * @key gc
  * @summary Verify that -XX:-ShrinkHeapInSteps works properly.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/arguments/TestSurvivorRatioFlag.java	2020-01-17 17:14:57.942114618 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestSurvivorRatioFlag.java	2020-01-17 17:14:57.842114624 +0100
@@ -25,7 +25,7 @@
  * @test TestSurvivorRatioFlag
  * @key gc
  * @summary Verify that actual survivor ratio is equal to specified SurvivorRatio value
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/arguments/TestTargetSurvivorRatioFlag.java	2020-01-17 17:14:58.523114586 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestTargetSurvivorRatioFlag.java	2020-01-17 17:14:58.423114592 +0100
@@ -27,7 +27,7 @@
  * @summary Verify that option TargetSurvivorRatio affects survivor space occupancy after minor GC.
  * @requires (vm.opt.ExplicitGCInvokesConcurrent == null) | (vm.opt.ExplicitGCInvokesConcurrent == false)
  * @requires (vm.opt.UseJVMCICompiler == null) | (vm.opt.UseJVMCICompiler == false)
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/arguments/TestUseCompressedOopsErgo.java	2020-01-17 17:14:59.104114554 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestUseCompressedOopsErgo.java	2020-01-17 17:14:59.003114560 +0100
@@ -54,6 +54,21 @@
  * @run main/othervm TestUseCompressedOopsErgo -XX:+UseConcMarkSweepGC
  */
 
+/*
+ * @test TestUseCompressedOopsErgoShenandoah
+ * @key gc
+ * @bug 8010722
+ * @comment Graal does not support Shenandoah
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ *          java.management/sun.management
+ * @build sun.hotspot.WhiteBox
+ * @run driver ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm TestUseCompressedOopsErgo -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC
+ */
+
 public class TestUseCompressedOopsErgo {
 
   public static void main(String args[]) throws Exception {
--- old/test/hotspot/jtreg/gc/arguments/TestVerifyBeforeAndAfterGCFlags.java	2020-01-17 17:14:59.678114523 +0100
+++ new/test/hotspot/jtreg/gc/arguments/TestVerifyBeforeAndAfterGCFlags.java	2020-01-17 17:14:59.581114528 +0100
@@ -28,7 +28,7 @@
  * @summary Runs an simple application (GarbageProducer) with various
          combinations of -XX:{+|-}Verify{After|Before}GC flags and checks that
          output contain or doesn't contain expected patterns
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  * @modules java.management
  * @library /test/lib
--- old/test/hotspot/jtreg/gc/class_unloading/TestClassUnloadingDisabled.java	2020-01-17 17:15:00.255114491 +0100
+++ new/test/hotspot/jtreg/gc/class_unloading/TestClassUnloadingDisabled.java	2020-01-17 17:15:00.155114496 +0100
@@ -64,6 +64,24 @@
  *                   -XX:-ClassUnloading -XX:+UseConcMarkSweepGC TestClassUnloadingDisabled
  */
 
+/*
+ * @test TestClassUnloadingDisabledShenandoah
+ * @key gc
+ * @bug 8114823
+ * @comment Graal does not support Shenandoah
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.opt.ExplicitGCInvokesConcurrent != true
+ * @requires vm.opt.ClassUnloading != true
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ *          java.management
+ * @build sun.hotspot.WhiteBox
+ * @run driver ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
+ *                   -XX:-ClassUnloading -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC TestClassUnloadingDisabled
+ */
+
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
--- old/test/hotspot/jtreg/gc/ergonomics/TestDynamicNumberOfGCThreads.java	2020-01-17 17:15:00.837114459 +0100
+++ new/test/hotspot/jtreg/gc/ergonomics/TestDynamicNumberOfGCThreads.java	2020-01-17 17:15:00.737114464 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,10 +29,14 @@
  * @key gc
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
+ * @build sun.hotspot.WhiteBox
+ * @run driver ClassFileInstaller sun.hotspot.WhiteBox sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDynamicNumberOfGCThreads
  */
 
 import jdk.test.lib.process.OutputAnalyzer;
 import jdk.test.lib.process.ProcessTools;
+import sun.hotspot.gc.GC;
 
 public class TestDynamicNumberOfGCThreads {
   public static void main(String[] args) throws Exception {
@@ -42,6 +46,10 @@
     testDynamicNumberOfGCThreads("UseG1GC");
 
     testDynamicNumberOfGCThreads("UseParallelGC");
+
+    if (GC.Shenandoah.isSupported()) {
+        testDynamicNumberOfGCThreads("UseShenandoahGC");
+    }
   }
 
   private static void verifyDynamicNumberOfGCThreads(OutputAnalyzer output) {
@@ -51,7 +59,7 @@
 
   private static void testDynamicNumberOfGCThreads(String gcFlag) throws Exception {
     // UseDynamicNumberOfGCThreads and TraceDynamicGCThreads enabled
-    String[] baseArgs = {"-XX:+" + gcFlag, "-Xmx10M", "-XX:+UseDynamicNumberOfGCThreads", "-Xlog:gc+task=trace", GCTest.class.getName()};
+    String[] baseArgs = {"-XX:+UnlockExperimentalVMOptions", "-XX:+" + gcFlag, "-Xmx10M", "-XX:+UseDynamicNumberOfGCThreads", "-Xlog:gc+task=trace", GCTest.class.getName()};
 
     // Base test with gc and +UseDynamicNumberOfGCThreads:
     ProcessBuilder pb_enabled = ProcessTools.createJavaProcessBuilder(baseArgs);
--- old/test/hotspot/jtreg/gc/ergonomics/TestInitialGCThreadLogging.java	2020-01-17 17:15:01.418114427 +0100
+++ new/test/hotspot/jtreg/gc/ergonomics/TestInitialGCThreadLogging.java	2020-01-17 17:15:01.317114432 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,10 +29,14 @@
  * @key gc
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
+ * @build sun.hotspot.WhiteBox
+ * @run driver ClassFileInstaller sun.hotspot.WhiteBox sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestInitialGCThreadLogging
  */
 
 import jdk.test.lib.process.ProcessTools;
 import jdk.test.lib.process.OutputAnalyzer;
+import sun.hotspot.gc.GC;
 
 public class TestInitialGCThreadLogging {
   public static void main(String[] args) throws Exception {
@@ -42,6 +46,10 @@
     testInitialGCThreadLogging("UseG1GC", "GC Thread");
 
     testInitialGCThreadLogging("UseParallelGC", "ParGC Thread");
+
+    if (GC.Shenandoah.isSupported()) {
+        testInitialGCThreadLogging("UseShenandoahGC", "Shenandoah GC Thread");
+    }
   }
 
   private static void verifyDynamicNumberOfGCThreads(OutputAnalyzer output, String threadName) {
@@ -51,7 +59,7 @@
 
   private static void testInitialGCThreadLogging(String gcFlag, String threadName) throws Exception {
     // UseDynamicNumberOfGCThreads and TraceDynamicGCThreads enabled
-    String[] baseArgs = {"-XX:+" + gcFlag, "-Xmx10M", "-XX:+UseDynamicNumberOfGCThreads", "-Xlog:gc+task=trace", "-version"};
+    String[] baseArgs = {"-XX:+UnlockExperimentalVMOptions", "-XX:+" + gcFlag, "-Xmx10M", "-XX:+UseDynamicNumberOfGCThreads", "-Xlog:gc+task=trace", "-version"};
 
     // Base test with gc and +UseDynamicNumberOfGCThreads:
     ProcessBuilder pb_enabled = ProcessTools.createJavaProcessBuilder(baseArgs);
--- old/test/hotspot/jtreg/gc/logging/TestGCId.java	2020-01-17 17:15:01.997114395 +0100
+++ new/test/hotspot/jtreg/gc/logging/TestGCId.java	2020-01-17 17:15:01.896114400 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -30,10 +30,14 @@
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
+ * @build sun.hotspot.WhiteBox
+ * @run driver ClassFileInstaller sun.hotspot.WhiteBox sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestGCId
  */
 
 import jdk.test.lib.process.OutputAnalyzer;
 import jdk.test.lib.process.ProcessTools;
+import sun.hotspot.gc.GC;
 
 public class TestGCId {
   public static void main(String[] args) throws Exception {
@@ -41,6 +45,9 @@
     testGCId("UseG1GC");
     testGCId("UseConcMarkSweepGC");
     testGCId("UseSerialGC");
+    if (GC.Shenandoah.isSupported()) {
+        testGCId("UseShenandoahGC");
+    }
   }
 
   private static void verifyContainsGCIDs(OutputAnalyzer output) {
@@ -51,7 +58,7 @@
 
   private static void testGCId(String gcFlag) throws Exception {
     ProcessBuilder pb_default =
-      ProcessTools.createJavaProcessBuilder("-XX:+" + gcFlag, "-Xlog:gc", "-Xmx10M", GCTest.class.getName());
+      ProcessTools.createJavaProcessBuilder("-XX:+UnlockExperimentalVMOptions", "-XX:+" + gcFlag, "-Xlog:gc", "-Xmx10M", GCTest.class.getName());
     verifyContainsGCIDs(new OutputAnalyzer(pb_default.start()));
   }
 
--- old/test/hotspot/jtreg/gc/metaspace/TestMetaspacePerfCounters.java	2020-01-17 17:15:02.567114363 +0100
+++ new/test/hotspot/jtreg/gc/metaspace/TestMetaspacePerfCounters.java	2020-01-17 17:15:02.469114369 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -53,6 +53,20 @@
  * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:+UseCompressedOops -XX:+UseCompressedClassPointers -XX:+UsePerfData -XX:+UseParallelGC -XX:+UseParallelOldGC TestMetaspacePerfCounters
  * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:+UseCompressedOops -XX:+UseCompressedClassPointers -XX:+UsePerfData -XX:+UseG1GC TestMetaspacePerfCounters
  */
+
+/* @test TestMetaspacePerfCountersShenandoah
+ * @bug 8014659
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @library /test/lib /
+ * @summary Tests that performance counters for metaspace and compressed class
+ *          space exists and works.
+ * @modules java.base/jdk.internal.misc
+ *          java.compiler
+ *          java.management/sun.management
+ *          jdk.internal.jvmstat/sun.jvmstat.monitor
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:-UseCompressedOops -XX:-UseCompressedClassPointers -XX:+UsePerfData -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC TestMetaspacePerfCounters
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:+UseCompressedOops -XX:+UseCompressedClassPointers -XX:+UsePerfData -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC TestMetaspacePerfCounters
+ */
 public class TestMetaspacePerfCounters {
     public static Class fooClass = null;
     private static final String[] counterNames = {"minCapacity", "maxCapacity", "capacity", "used"};
--- old/test/hotspot/jtreg/gc/survivorAlignment/TestAllocationInEden.java	2020-01-17 17:15:03.149114331 +0100
+++ new/test/hotspot/jtreg/gc/survivorAlignment/TestAllocationInEden.java	2020-01-17 17:15:03.048114337 +0100
@@ -26,7 +26,7 @@
  * @bug 8031323
  * @summary Verify that object's alignment in eden space is not affected by
  *          SurvivorAlignmentInBytes option.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionFromEdenToTenured.java	2020-01-17 17:15:03.724114300 +0100
+++ new/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionFromEdenToTenured.java	2020-01-17 17:15:03.623114305 +0100
@@ -26,7 +26,7 @@
  * @bug 8031323
  * @summary Verify that objects promoted from eden space to tenured space during
  *          full GC are not aligned to SurvivorAlignmentInBytes value.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionFromSurvivorToTenuredAfterFullGC.java	2020-01-17 17:15:04.296114268 +0100
+++ new/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionFromSurvivorToTenuredAfterFullGC.java	2020-01-17 17:15:04.199114273 +0100
@@ -26,7 +26,7 @@
  * @bug 8031323
  * @summary Verify that objects promoted from survivor space to tenured space
  *          during full GC are not aligned to SurvivorAlignmentInBytes value.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionFromSurvivorToTenuredAfterMinorGC.java	2020-01-17 17:15:04.877114236 +0100
+++ new/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionFromSurvivorToTenuredAfterMinorGC.java	2020-01-17 17:15:04.776114242 +0100
@@ -27,7 +27,7 @@
  * @summary Verify that objects promoted from survivor space to tenured space
  *          when their age exceeded tenuring threshold are not aligned to
  *          SurvivorAlignmentInBytes value.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionToSurvivor.java	2020-01-17 17:15:05.446114205 +0100
+++ new/test/hotspot/jtreg/gc/survivorAlignment/TestPromotionToSurvivor.java	2020-01-17 17:15:05.345114210 +0100
@@ -26,7 +26,7 @@
  * @bug 8031323
  * @summary Verify that objects promoted from eden space to survivor space after
  *          minor GC are aligned to SurvivorAlignmentInBytes.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/gc/whitebox/TestWBGC.java	2020-01-17 17:15:06.015114173 +0100
+++ new/test/hotspot/jtreg/gc/whitebox/TestWBGC.java	2020-01-17 17:15:05.916114179 +0100
@@ -25,7 +25,7 @@
  * @test TestWBGC
  * @bug 8055098
  * @summary Test verify that WB methods isObjectInOldGen and youngGC works correctly.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @library /test/lib
  * @modules java.base/jdk.internal.misc
  *          java.management
--- old/test/hotspot/jtreg/resourcehogs/serviceability/sa/TestHeapDumpForLargeArray.java	2020-01-17 17:15:06.596114141 +0100
+++ new/test/hotspot/jtreg/resourcehogs/serviceability/sa/TestHeapDumpForLargeArray.java	2020-01-17 17:15:06.498114147 +0100
@@ -47,6 +47,7 @@
  * @library /test/lib
  * @bug 8171084
  * @requires vm.hasSAandCanAttach & (vm.bits == "64" & os.maxMemory > 8g)
+ * @requires vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  *          jdk.hotspot.agent/sun.jvm.hotspot
  *          jdk.hotspot.agent/sun.jvm.hotspot.utilities
--- old/test/hotspot/jtreg/runtime/CompressedOops/UseCompressedOops.java	2020-01-17 17:15:07.174114110 +0100
+++ new/test/hotspot/jtreg/runtime/CompressedOops/UseCompressedOops.java	2020-01-17 17:15:07.073114115 +0100
@@ -37,6 +37,7 @@
 import jdk.test.lib.Platform;
 import jdk.test.lib.process.ProcessTools;
 import jdk.test.lib.process.OutputAnalyzer;
+import sun.hotspot.gc.GC;
 
 import sun.hotspot.code.Compiler;
 
@@ -61,6 +62,9 @@
         testCompressedOopsModes(args, "-XX:+UseSerialGC");
         testCompressedOopsModes(args, "-XX:+UseParallelGC");
         testCompressedOopsModes(args, "-XX:+UseParallelOldGC");
+        if (GC.Shenandoah.isSupported()) {
+            testCompressedOopsModes(args, "-XX:+UnlockExperimentalVMOptions", "-XX:+UseShenandoahGC");
+        }
     }
 
     public static void testCompressedOopsModes(ArrayList<String> flags1, String... flags2) throws Exception {
--- old/test/hotspot/jtreg/runtime/MemberName/MemberNameLeak.java	2020-01-17 17:15:07.752114078 +0100
+++ new/test/hotspot/jtreg/runtime/MemberName/MemberNameLeak.java	2020-01-17 17:15:07.655114083 +0100
@@ -36,6 +36,7 @@
 import jdk.test.lib.process.ProcessTools;
 
 import sun.hotspot.code.Compiler;
+import sun.hotspot.gc.GC;
 
 public class MemberNameLeak {
     static class Leak {
@@ -61,6 +62,7 @@
        // Run this Leak class with logging
         ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
                                       "-Xlog:membername+table=trace",
+                                      "-XX:+UnlockExperimentalVMOptions",
                                       gc, Leak.class.getName());
         OutputAnalyzer output = new OutputAnalyzer(pb.start());
         output.shouldContain("ResolvedMethod entry added for MemberNameLeak$Leak.callMe()V");
@@ -73,8 +75,11 @@
         test("-XX:+UseG1GC");
         test("-XX:+UseParallelGC");
         test("-XX:+UseSerialGC");
-        if (!Compiler.isGraalEnabled()) { // Graal does not support CMS
+        if (!Compiler.isGraalEnabled()) { // Graal does not support CMS and Shenandoah
             test("-XX:+UseConcMarkSweepGC");
+            if (GC.Shenandoah.isSupported()) {
+                test("-XX:+UseShenandoahGC");
+            }
         }
     }
 }
--- old/test/hotspot/jtreg/serviceability/sa/ClhsdbJhisto.java	2020-01-17 17:15:08.312114047 +0100
+++ new/test/hotspot/jtreg/serviceability/sa/ClhsdbJhisto.java	2020-01-17 17:15:08.218114052 +0100
@@ -34,6 +34,7 @@
  * @bug 8191658
  * @summary Test clhsdb jhisto command
  * @requires vm.hasSA
+ * @requires vm.gc != "Shenandoah"
  * @library /test/lib
  * @run main/othervm ClhsdbJhisto
  */
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCapacityTest.java	2020-01-17 17:15:08.888114015 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCapacityTest.java	2020-01-17 17:15:08.787114021 +0100
@@ -27,7 +27,7 @@
  * @test
  * @summary Test checks the consistency of the output
  * displayed with jstat -gccapacity.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
  * @library ../share
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCauseTest01.java	2020-01-17 17:15:09.464113983 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCauseTest01.java	2020-01-17 17:15:09.362113989 +0100
@@ -32,7 +32,7 @@
  * @library /test/lib
  * @library ../share
  * @requires vm.opt.ExplicitGCInvokesConcurrent != true
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @run main/othervm -XX:+UsePerfData -Xmx128M GcCauseTest01
  */
 import utils.*;
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCauseTest02.java	2020-01-17 17:15:10.036113952 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCauseTest02.java	2020-01-17 17:15:09.938113957 +0100
@@ -28,7 +28,7 @@
  *          test forces debuggee application eat ~70% of heap and runs jstat.
  *          jstat should show actual usage of old gen (OC/OU ~= old gen usage).
  * @requires vm.opt.ExplicitGCInvokesConcurrent != true
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
  * @library ../share
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCauseTest03.java	2020-01-17 17:15:10.610113920 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcCauseTest03.java	2020-01-17 17:15:10.513113926 +0100
@@ -27,7 +27,7 @@
  *          Test scenario:
  *          test forces debuggee application call System.gc(), runs jstat and checks that
  *          cause of last garbage collection displayed by jstat (LGCC) is 'System.gc()'.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
  * @library ../share
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcNewTest.java	2020-01-17 17:15:11.175113889 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcNewTest.java	2020-01-17 17:15:11.079113894 +0100
@@ -29,7 +29,7 @@
  *          test several times provokes garbage collection in the debuggee application and after each garbage
  *          collection runs jstat. jstat should show that after garbage collection number of GC events and garbage
  *          collection time increase.
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
  * @library ../share
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcTest01.java	2020-01-17 17:15:11.746113858 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcTest01.java	2020-01-17 17:15:11.646113863 +0100
@@ -35,7 +35,7 @@
  * @library /test/lib
  * @library ../share
  * @requires vm.opt.ExplicitGCInvokesConcurrent != true
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @run main/othervm -XX:+UsePerfData -Xmx128M GcTest01
  */
 import utils.*;
--- old/test/hotspot/jtreg/serviceability/tmtools/jstat/GcTest02.java	2020-01-17 17:15:12.321113826 +0100
+++ new/test/hotspot/jtreg/serviceability/tmtools/jstat/GcTest02.java	2020-01-17 17:15:12.221113831 +0100
@@ -28,7 +28,7 @@
  *          test forces debuggee application eat ~70% of heap and runs jstat.
  *          jstat should show actual usage of old gen (OC/OU ~= old gen usage).
  * @requires vm.opt.ExplicitGCInvokesConcurrent != true
- * @requires vm.gc != "Z"
+ * @requires vm.gc != "Z" & vm.gc != "Shenandoah"
  * @modules java.base/jdk.internal.misc
  * @library /test/lib
  * @library ../share
--- old/test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/general_functions/GF08/gf08t001/TestDriver.java	2020-01-17 17:15:12.886113795 +0100
+++ new/test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/general_functions/GF08/gf08t001/TestDriver.java	2020-01-17 17:15:12.789113800 +0100
@@ -72,15 +72,16 @@
         Boolean isUseG1GCon = wb.getBooleanVMFlag("UseG1GC");
         Boolean isUseConcMarkSweepGCon = wb.getBooleanVMFlag("UseConcMarkSweepGC");
         Boolean isUseZGCon = wb.getBooleanVMFlag("UseZGC");
+        Boolean isShenandoahGCon = wb.getBooleanVMFlag("UseShenandoahGC");
         Boolean isUseEpsilonGCon = wb.getBooleanVMFlag("UseEpsilonGC");
 
         if (Compiler.isGraalEnabled() &&
-            (isUseConcMarkSweepGCon || isUseZGCon || isUseEpsilonGCon)) {
+            (isUseConcMarkSweepGCon || isUseZGCon || isUseEpsilonGCon || isShenandoahGCon)) {
             return; // Graal does not support these GCs
         }
 
         String keyPhrase;
-        if ((isExplicitGCInvokesConcurrentOn && (isUseG1GCon || isUseConcMarkSweepGCon)) || isUseZGCon) {
+        if ((isExplicitGCInvokesConcurrentOn && (isUseG1GCon || isUseConcMarkSweepGCon)) || isUseZGCon || isShenandoahGCon) {
             keyPhrase = "GC";
         } else {
             keyPhrase = "Pause Full";
--- old/test/lib/jdk/test/lib/jfr/EventNames.java	2020-01-17 17:15:13.458113763 +0100
+++ new/test/lib/jdk/test/lib/jfr/EventNames.java	2020-01-17 17:15:13.361113769 +0100
@@ -98,6 +98,8 @@
     public final static String G1HeapSummary = PREFIX + "G1HeapSummary";
     public final static String G1HeapRegionInformation = PREFIX + "G1HeapRegionInformation";
     public final static String G1HeapRegionTypeChange = PREFIX + "G1HeapRegionTypeChange";
+    public final static String ShenandoahHeapRegionInformation = PREFIX + "ShenandoahHeapRegionInformation";
+    public final static String ShenandoahHeapRegionStateChange = PREFIX + "ShenandoahHeapRegionStateChange";
     public final static String TenuringDistribution = PREFIX + "TenuringDistribution";
     public final static String GarbageCollection = PREFIX + "GarbageCollection";
     public final static String ParallelOldCollection = PREFIX + "ParallelOldGarbageCollection";
--- old/test/lib/jdk/test/lib/jfr/GCHelper.java	2020-01-17 17:15:14.031113732 +0100
+++ new/test/lib/jdk/test/lib/jfr/GCHelper.java	2020-01-17 17:15:13.931113737 +0100
@@ -80,6 +80,7 @@
     public static final String pauseLevelEvent = "GCPhasePauseLevel";
 
     private static final List<String> g1HeapRegionTypes;
+    private static final List<String> shenandoahHeapRegionStates;
     private static PrintStream defaultErrorLog = null;
 
     public static int getGcId(RecordedEvent event) {
@@ -207,6 +208,21 @@
                                                          };
 
         g1HeapRegionTypes = Collections.unmodifiableList(Arrays.asList(g1HeapRegionTypeLiterals));
+
+        String[] shenandoahHeapRegionStateLiterals = new String[] {
+                                                                    "Empty Uncommitted",
+                                                                    "Empty Committed",
+                                                                    "Regular",
+                                                                    "Humongous Start",
+                                                                    "Humongous Continuation",
+                                                                    "Humongous Start, Pinned",
+                                                                    "Collection Set",
+                                                                    "Pinned",
+                                                                    "Collection Set, Pinned",
+                                                                    "Trash"
+        };
+
+        shenandoahHeapRegionStates = Collections.unmodifiableList(Arrays.asList(shenandoahHeapRegionStateLiterals));
     }
 
     /**
@@ -443,6 +459,13 @@
         return g1HeapRegionTypes.contains(type);
     }
 
+    public static boolean assertIsValidShenandoahHeapRegionState(final String state) {
+        if (!shenandoahHeapRegionStates.contains(state)) {
+            throw new AssertionError("Unknown state '" + state + "', valid heap region states are " + shenandoahHeapRegionStates);
+        }
+        return true;
+    }
+
     /**
      * Helper function to align heap size up.
      *
--- old/test/lib/sun/hotspot/gc/GC.java	2020-01-17 17:15:14.610113700 +0100
+++ new/test/lib/sun/hotspot/gc/GC.java	2020-01-17 17:15:14.510113705 +0100
@@ -38,7 +38,8 @@
     ConcMarkSweep(3),
     G1(4),
     Epsilon(5),
-    Z(6);
+    Z(6),
+    Shenandoah(7);
 
     private static final WhiteBox WB = WhiteBox.getWhiteBox();
 
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shared/markBitMap.cpp	2020-01-17 17:15:15.078113674 +0100
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+// Concurrent marking bit map wrapper
+
+#include "precompiled.hpp"
+#include "gc/shared/markBitMap.inline.hpp"
+#include "utilities/bitMap.inline.hpp"
+
+MarkBitMapRO::MarkBitMapRO(int shifter) :
+  _bm(),
+  _shifter(shifter) {
+  _bmStartWord = 0;
+  _bmWordSize = 0;
+}
+
+#ifndef PRODUCT
+bool MarkBitMapRO::covers(MemRegion heap_rs) const {
+  // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
+  assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
+         "size inconsistency");
+  return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
+         _bmWordSize  == heap_rs.word_size();
+}
+#endif
+
+void MarkBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
+  _bm.print_on_error(st, prefix);
+}
+
+size_t MarkBitMap::compute_size(size_t heap_size) {
+  return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
+}
+
+size_t MarkBitMap::mark_distance() {
+  return MinObjAlignmentInBytes * BitsPerByte;
+}
+
+void MarkBitMap::initialize(MemRegion heap, MemRegion bitmap) {
+  _bmStartWord = heap.start();
+  _bmWordSize = heap.word_size();
+
+  _bm = BitMapView((BitMap::bm_word_t*) bitmap.start(), _bmWordSize >> _shifter);
+  _covered = heap;
+}
+
+void MarkBitMap::do_clear(MemRegion mr, bool large) {
+  MemRegion intersection = mr.intersection(_covered);
+  assert(!intersection.is_empty(),
+         "Given range from " PTR_FORMAT " to " PTR_FORMAT " is completely outside the heap",
+         p2i(mr.start()), p2i(mr.end()));
+  // convert address range into offset range
+  size_t beg = heapWordToOffset(intersection.start());
+  size_t end = heapWordToOffset(intersection.end());
+  if (large) {
+    _bm.clear_large_range(beg, end);
+  } else {
+    _bm.clear_range(beg, end);
+  }
+}
+
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shared/markBitMap.hpp	2020-01-17 17:15:15.675113641 +0100
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_CMBITMAP_HPP
+#define SHARE_VM_GC_SHARED_CMBITMAP_HPP
+
+#include "memory/memRegion.hpp"
+#include "utilities/bitMap.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// A generic CM bit map.  This is essentially a wrapper around the BitMap
+// class, with one bit per (1<<_shifter) HeapWords.
+
+class MarkBitMapRO {
+ protected:
+  MemRegion _covered;      // The heap area covered by this bitmap.
+  HeapWord* _bmStartWord;  // base address of range covered by map
+  size_t    _bmWordSize;   // map size (in #HeapWords covered)
+  const int _shifter;      // map to char or bit
+  BitMapView _bm;          // the bit map itself
+
+ public:
+  // constructor
+  MarkBitMapRO(int shifter);
+
+  // inquiries
+  HeapWord* startWord()   const { return _bmStartWord; }
+  // the following is one past the last word in space
+  HeapWord* endWord()     const { return _bmStartWord + _bmWordSize; }
+
+  // read marks
+
+  bool isMarked(HeapWord* addr) const {
+    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
+           "outside underlying space?");
+    return _bm.at(heapWordToOffset(addr));
+  }
+
+  // iteration
+  inline bool iterate(BitMapClosure* cl, MemRegion mr);
+
+  // Return the address corresponding to the next marked bit at or after
+  // "addr", and before "limit", if "limit" is non-NULL.  If there is no
+  // such bit, returns "limit" if that is non-NULL, or else "endWord()".
+  inline HeapWord* getNextMarkedWordAddress(const HeapWord* addr,
+                                     const HeapWord* limit = NULL) const;
+
+  // conversion utilities
+  HeapWord* offsetToHeapWord(size_t offset) const {
+    return _bmStartWord + (offset << _shifter);
+  }
+  size_t heapWordToOffset(const HeapWord* addr) const {
+    return pointer_delta(addr, _bmStartWord) >> _shifter;
+  }
+
+  // The argument addr should be the start address of a valid object
+  inline HeapWord* nextObject(HeapWord* addr);
+
+  void print_on_error(outputStream* st, const char* prefix) const;
+
+  // debugging
+  NOT_PRODUCT(bool covers(MemRegion rs) const;)
+};
+
+class MarkBitMap : public MarkBitMapRO {
+ private:
+  // Clear bitmap range
+  void do_clear(MemRegion mr, bool large);
+
+ public:
+  static size_t compute_size(size_t heap_size);
+  // Returns the amount of bytes on the heap between two marks in the bitmap.
+  static size_t mark_distance();
+  // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
+  // mark bitmap corresponds to. This is the same as the mark distance above.  static size_t heap_map_factor() {
+  static size_t heap_map_factor() {
+    return mark_distance();
+  }
+
+  MarkBitMap() : MarkBitMapRO(LogMinObjAlignment) {}
+
+  // Initializes the underlying BitMap to cover the given area.
+  void initialize(MemRegion heap, MemRegion bitmap);
+
+  // Write marks.
+  inline void mark(HeapWord* addr);
+  inline void clear(HeapWord* addr);
+  inline bool parMark(HeapWord* addr);
+
+  // Clear range. For larger regions, use *_large.
+  void clear()                         { do_clear(_covered, true); }
+  void clear_range(MemRegion mr)       { do_clear(mr, false);      }
+  void clear_range_large(MemRegion mr) { do_clear(mr, true);       }
+};
+
+#endif // SHARE_VM_GC_SHARED_CMBITMAP_HPP
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shared/markBitMap.inline.hpp	2020-01-17 17:15:16.266113609 +0100
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_CMBITMAP_INLINE_HPP
+#define SHARE_VM_GC_SHARED_CMBITMAP_INLINE_HPP
+
+#include "gc/shared/markBitMap.hpp"
+#include "oops/oop.inline.hpp"
+#include "utilities/bitMap.inline.hpp"
+#include "utilities/align.hpp"
+
+inline HeapWord* MarkBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
+                                               const HeapWord* limit) const {
+  // First we must round addr *up* to a possible object boundary.
+  addr = (HeapWord*)align_up((intptr_t)addr,
+                                  HeapWordSize << _shifter);
+  size_t addrOffset = heapWordToOffset(addr);
+  assert(limit != NULL, "limit must not be NULL");
+  size_t limitOffset = heapWordToOffset(limit);
+  size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
+  HeapWord* nextAddr = offsetToHeapWord(nextOffset);
+  assert(nextAddr >= addr, "get_next_one postcondition");
+  assert(nextAddr == limit || isMarked(nextAddr),
+         "get_next_one postcondition");
+  return nextAddr;
+}
+
+inline bool MarkBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
+  HeapWord* start_addr = MAX2(startWord(), mr.start());
+  HeapWord* end_addr = MIN2(endWord(), mr.end());
+
+  if (end_addr > start_addr) {
+    // Right-open interval [start-offset, end-offset).
+    BitMap::idx_t start_offset = heapWordToOffset(start_addr);
+    BitMap::idx_t end_offset = heapWordToOffset(end_addr);
+
+    start_offset = _bm.get_next_one_offset(start_offset, end_offset);
+    while (start_offset < end_offset) {
+      if (!cl->do_bit(start_offset)) {
+        return false;
+      }
+      HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
+      BitMap::idx_t next_offset = heapWordToOffset(next_addr);
+      start_offset = _bm.get_next_one_offset(next_offset, end_offset);
+    }
+  }
+  return true;
+}
+
+// The argument addr should be the start address of a valid object
+HeapWord* MarkBitMapRO::nextObject(HeapWord* addr) {
+  oop obj = (oop) addr;
+  HeapWord* res =  addr + obj->size();
+  assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
+  return res;
+}
+
+#define check_mark(addr)                                                       \
+  assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize),      \
+         "outside underlying space?");                                         \
+  /* assert(G1CollectedHeap::heap()->is_in_exact(addr),                  \
+         err_msg("Trying to access not available bitmap "PTR_FORMAT            \
+                 " corresponding to "PTR_FORMAT" (%u)",                        \
+                 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr))); */
+
+inline void MarkBitMap::mark(HeapWord* addr) {
+  check_mark(addr);
+  _bm.set_bit(heapWordToOffset(addr));
+}
+
+inline void MarkBitMap::clear(HeapWord* addr) {
+  check_mark(addr);
+  _bm.clear_bit(heapWordToOffset(addr));
+}
+
+inline bool MarkBitMap::parMark(HeapWord* addr) {
+  check_mark(addr);
+  return _bm.par_set_bit(heapWordToOffset(addr));
+}
+
+#undef check_mark
+
+#endif // SHARE_VM_GC_SHARED_CMBITMAP_INLINE_HPP
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shared/parallelCleaning.cpp	2020-01-17 17:15:16.871113575 +0100
@@ -0,0 +1,331 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/symbolTable.hpp"
+#include "classfile/stringTable.hpp"
+#include "code/codeCache.hpp"
+#include "gc/shared/parallelCleaning.hpp"
+#include "memory/resourceArea.hpp"
+#include "prims/resolvedMethodTable.hpp"
+#include "logging/log.hpp"
+#include "gc/shared/gcCause.hpp"
+#include "gc/shared/gcTraceTime.hpp"
+#include "gc/shared/gcTraceTime.inline.hpp"
+
+StringSymbolTableUnlinkTask::StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
+  AbstractGangTask("String/Symbol Unlinking"),
+  _is_alive(is_alive),
+  _par_state_string(StringTable::weak_storage()),
+  _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
+  _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
+
+  _initial_string_table_size = (int) StringTable::the_table()->table_size();
+  _initial_symbol_table_size = SymbolTable::the_table()->table_size();
+  if (process_symbols) {
+    SymbolTable::clear_parallel_claimed_index();
+  }
+}
+
+StringSymbolTableUnlinkTask::~StringSymbolTableUnlinkTask() {
+  guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
+            "claim value %d after unlink less than initial symbol table size %d",
+            SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
+
+  log_info(gc, stringtable)(
+      "Cleaned string and symbol table, "
+      "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
+      "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
+      strings_processed(), strings_removed(),
+      symbols_processed(), symbols_removed());
+}
+
+void StringSymbolTableUnlinkTask::work(uint worker_id) {
+  int strings_processed = 0;
+  int strings_removed = 0;
+  int symbols_processed = 0;
+  int symbols_removed = 0;
+  if (_process_strings) {
+    StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
+    Atomic::add(strings_processed, &_strings_processed);
+    Atomic::add(strings_removed, &_strings_removed);
+  }
+  if (_process_symbols) {
+    SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
+    Atomic::add(symbols_processed, &_symbols_processed);
+    Atomic::add(symbols_removed, &_symbols_removed);
+  }
+}
+
+size_t StringSymbolTableUnlinkTask::strings_processed() const { return (size_t)_strings_processed; }
+size_t StringSymbolTableUnlinkTask::strings_removed()   const { return (size_t)_strings_removed; }
+
+size_t StringSymbolTableUnlinkTask::symbols_processed() const { return (size_t)_symbols_processed; }
+size_t StringSymbolTableUnlinkTask::symbols_removed()   const { return (size_t)_symbols_removed; }
+
+
+Monitor* CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
+
+CodeCacheUnloadingTask::CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
+  _is_alive(is_alive),
+  _unloading_occurred(unloading_occurred),
+  _num_workers(num_workers),
+  _first_nmethod(NULL),
+  _claimed_nmethod(NULL),
+  _postponed_list(NULL),
+  _num_entered_barrier(0)
+{
+  CompiledMethod::increase_unloading_clock();
+  // Get first alive nmethod
+  CompiledMethodIterator iter = CompiledMethodIterator();
+  if(iter.next_alive()) {
+    _first_nmethod = iter.method();
+  }
+  _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
+}
+
+CodeCacheUnloadingTask::~CodeCacheUnloadingTask() {
+  CodeCache::verify_clean_inline_caches();
+
+  CodeCache::set_needs_cache_clean(false);
+  guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
+
+  CodeCache::verify_icholder_relocations();
+}
+
+void CodeCacheUnloadingTask::add_to_postponed_list(CompiledMethod* nm) {
+  CompiledMethod* old;
+  do {
+    old = (CompiledMethod*)_postponed_list;
+    nm->set_unloading_next(old);
+  } while ((CompiledMethod*)Atomic::cmpxchg(nm, &_postponed_list, old) != old);
+}
+
+void CodeCacheUnloadingTask::clean_nmethod(CompiledMethod* nm) {
+  bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
+
+  if (postponed) {
+    // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
+    add_to_postponed_list(nm);
+  }
+
+  // Mark that this thread has been cleaned/unloaded.
+  // After this call, it will be safe to ask if this nmethod was unloaded or not.
+  nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
+}
+
+void CodeCacheUnloadingTask::clean_nmethod_postponed(CompiledMethod* nm) {
+  nm->do_unloading_parallel_postponed();
+}
+
+void CodeCacheUnloadingTask::claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
+  CompiledMethod* first;
+  CompiledMethodIterator last;
+
+  do {
+    *num_claimed_nmethods = 0;
+
+    first = (CompiledMethod*)_claimed_nmethod;
+    last = CompiledMethodIterator(first);
+
+    if (first != NULL) {
+
+      for (int i = 0; i < MaxClaimNmethods; i++) {
+        if (!last.next_alive()) {
+          break;
+        }
+        claimed_nmethods[i] = last.method();
+        (*num_claimed_nmethods)++;
+      }
+    }
+
+  } while ((CompiledMethod*)Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
+}
+
+CompiledMethod* CodeCacheUnloadingTask::claim_postponed_nmethod() {
+  CompiledMethod* claim;
+  CompiledMethod* next;
+
+  do {
+    claim = (CompiledMethod*)_postponed_list;
+    if (claim == NULL) {
+      return NULL;
+    }
+
+    next = claim->unloading_next();
+
+  } while ((CompiledMethod*)Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
+
+  return claim;
+}
+
+// Mark that we're done with the first pass of nmethod cleaning.
+void CodeCacheUnloadingTask::barrier_mark(uint worker_id) {
+  MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+  _num_entered_barrier++;
+  if (_num_entered_barrier == _num_workers) {
+    ml.notify_all();
+  }
+}
+
+// See if we have to wait for the other workers to
+// finish their first-pass nmethod cleaning work.
+void CodeCacheUnloadingTask::barrier_wait(uint worker_id) {
+  if (_num_entered_barrier < _num_workers) {
+    MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+    while (_num_entered_barrier < _num_workers) {
+      ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
+    }
+  }
+}
+
+// Cleaning and unloading of nmethods. Some work has to be postponed
+// to the second pass, when we know which nmethods survive.
+void CodeCacheUnloadingTask::work_first_pass(uint worker_id) {
+  // The first nmethods is claimed by the first worker.
+  if (worker_id == 0 && _first_nmethod != NULL) {
+    clean_nmethod(_first_nmethod);
+    _first_nmethod = NULL;
+  }
+
+  int num_claimed_nmethods;
+  CompiledMethod* claimed_nmethods[MaxClaimNmethods];
+
+  while (true) {
+    claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
+
+    if (num_claimed_nmethods == 0) {
+      break;
+    }
+
+    for (int i = 0; i < num_claimed_nmethods; i++) {
+      clean_nmethod(claimed_nmethods[i]);
+    }
+  }
+}
+
+void CodeCacheUnloadingTask::work_second_pass(uint worker_id) {
+  CompiledMethod* nm;
+  // Take care of postponed nmethods.
+  while ((nm = claim_postponed_nmethod()) != NULL) {
+    clean_nmethod_postponed(nm);
+  }
+}
+
+KlassCleaningTask::KlassCleaningTask(BoolObjectClosure* is_alive) :
+  _is_alive(is_alive),
+  _clean_klass_tree_claimed(0),
+  _klass_iterator() {
+}
+
+bool KlassCleaningTask::claim_clean_klass_tree_task() {
+  if (_clean_klass_tree_claimed) {
+    return false;
+  }
+
+  return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
+}
+
+InstanceKlass* KlassCleaningTask::claim_next_klass() {
+  Klass* klass;
+  do {
+    klass =_klass_iterator.next_klass();
+  } while (klass != NULL && !klass->is_instance_klass());
+
+  // this can be null so don't call InstanceKlass::cast
+  return static_cast<InstanceKlass*>(klass);
+}
+
+void KlassCleaningTask::clean_klass(InstanceKlass* ik) {
+  ik->clean_weak_instanceklass_links();
+}
+
+void KlassCleaningTask::work() {
+  ResourceMark rm;
+
+  // One worker will clean the subklass/sibling klass tree.
+  if (claim_clean_klass_tree_task()) {
+    Klass::clean_subklass_tree();
+  }
+
+  // All workers will help cleaning the classes,
+  InstanceKlass* klass;
+  while ((klass = claim_next_klass()) != NULL) {
+    clean_klass(klass);
+  }
+}
+
+bool ResolvedMethodCleaningTask::claim_resolved_method_task() {
+  if (_resolved_method_task_claimed) {
+    return false;
+  }
+  return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
+}
+
+// These aren't big, one thread can do it all.
+void ResolvedMethodCleaningTask::work() {
+  if (claim_resolved_method_task()) {
+    ResolvedMethodTable::unlink();
+  }
+}
+
+ParallelCleaningTask::ParallelCleaningTask(BoolObjectClosure* is_alive,
+                                           bool process_strings,
+                                           bool process_symbols,
+                                           uint num_workers,
+                                           bool unloading_occurred) :
+  AbstractGangTask("Parallel Cleaning"),
+  _string_symbol_task(is_alive, process_strings, process_symbols),
+  _code_cache_task(num_workers, is_alive, unloading_occurred),
+  _klass_cleaning_task(is_alive),
+  _resolved_method_cleaning_task(is_alive)
+{
+
+
+}
+
+// The parallel work done by all worker threads.
+void ParallelCleaningTask::work(uint worker_id) {
+  // Do first pass of code cache cleaning.
+  _code_cache_task.work_first_pass(worker_id);
+
+  // Let the threads mark that the first pass is done.
+  _code_cache_task.barrier_mark(worker_id);
+
+  // Clean the Strings and Symbols.
+  _string_symbol_task.work(worker_id);
+
+  // Clean unreferenced things in the ResolvedMethodTable
+  _resolved_method_cleaning_task.work();
+
+  // Wait for all workers to finish the first code cache cleaning pass.
+  _code_cache_task.barrier_wait(worker_id);
+
+  // Do the second code cache cleaning work, which realize on
+  // the liveness information gathered during the first pass.
+  _code_cache_task.work_second_pass(worker_id);
+
+  // Clean all klasses that were not unloaded.
+  _klass_cleaning_task.work();
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shared/parallelCleaning.hpp	2020-01-17 17:15:17.470113542 +0100
@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_PARALLELCLEANING_HPP
+#define SHARE_VM_GC_SHARED_PARALLELCLEANING_HPP
+
+#include "gc/shared/oopStorageParState.hpp"
+#include "gc/shared/workgroup.hpp"
+
+class StringSymbolTableUnlinkTask : public AbstractGangTask {
+private:
+  BoolObjectClosure* _is_alive;
+  OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
+  int _initial_string_table_size;
+  int _initial_symbol_table_size;
+
+  bool  _process_strings;
+  volatile int _strings_processed;
+  volatile int _strings_removed;
+
+  bool  _process_symbols;
+  volatile int _symbols_processed;
+  volatile int _symbols_removed;
+
+public:
+  StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols);
+  ~StringSymbolTableUnlinkTask();
+
+  void work(uint worker_id);
+
+  size_t strings_processed() const;
+  size_t strings_removed()   const;
+
+  size_t symbols_processed() const;
+  size_t symbols_removed()   const;
+};
+
+class CodeCacheUnloadingTask {
+private:
+  static Monitor* _lock;
+
+  BoolObjectClosure* const _is_alive;
+  const bool               _unloading_occurred;
+  const uint               _num_workers;
+
+  // Variables used to claim nmethods.
+  CompiledMethod* _first_nmethod;
+  volatile CompiledMethod* _claimed_nmethod;
+
+  // The list of nmethods that need to be processed by the second pass.
+  volatile CompiledMethod* _postponed_list;
+  volatile uint     _num_entered_barrier;
+
+ public:
+  CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred);
+  ~CodeCacheUnloadingTask();
+
+ private:
+  void add_to_postponed_list(CompiledMethod* nm);
+
+  void clean_nmethod(CompiledMethod* nm);
+
+  void clean_nmethod_postponed(CompiledMethod* nm);
+
+  static const int MaxClaimNmethods = 16;
+
+  void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods);
+
+  CompiledMethod* claim_postponed_nmethod();
+
+ public:
+  // Mark that we're done with the first pass of nmethod cleaning.
+  void barrier_mark(uint worker_id);
+
+  // See if we have to wait for the other workers to
+  // finish their first-pass nmethod cleaning work.
+  void barrier_wait(uint worker_id);
+
+  // Cleaning and unloading of nmethods. Some work has to be postponed
+  // to the second pass, when we know which nmethods survive.
+  void work_first_pass(uint worker_id);
+
+  void work_second_pass(uint worker_id);
+};
+
+class KlassCleaningTask : public StackObj {
+  BoolObjectClosure*                      _is_alive;
+  volatile int                            _clean_klass_tree_claimed;
+  ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
+
+ public:
+  KlassCleaningTask(BoolObjectClosure* is_alive);
+
+ private:
+  bool claim_clean_klass_tree_task();
+
+  InstanceKlass* claim_next_klass();
+
+public:
+
+  void clean_klass(InstanceKlass* ik);
+
+  void work();
+};
+
+class ResolvedMethodCleaningTask : public StackObj {
+  BoolObjectClosure* _is_alive;
+  volatile int       _resolved_method_task_claimed;
+public:
+  ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
+          _is_alive(is_alive), _resolved_method_task_claimed(0) {}
+
+  bool claim_resolved_method_task();
+  void work();
+};
+
+// To minimize the remark pause times, the tasks below are done in parallel.
+class ParallelCleaningTask : public AbstractGangTask {
+private:
+  StringSymbolTableUnlinkTask _string_symbol_task;
+  CodeCacheUnloadingTask      _code_cache_task;
+  KlassCleaningTask           _klass_cleaning_task;
+  ResolvedMethodCleaningTask  _resolved_method_cleaning_task;
+
+public:
+  // The constructor is run in the VMThread.
+  ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred);
+
+  // The parallel work done by all worker threads.
+  void work(uint worker_id);
+};
+
+#endif // SHARE_VM_GC_SHARED_PARALLELCLEANING_HPP
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/hotspot/jtreg/compiler/c2/aarch64/TestVolatilesShenandoah.java	2020-01-17 17:15:18.074113509 +0100
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @summary C2 should use ldar, stlr and ldaxr+stlxr insns for volatile operations
+ * @library /test/lib /
+ *
+ * @modules java.base/jdk.internal.misc
+ *
+ * @requires os.arch=="aarch64" & vm.debug == true &
+ *           vm.flavor == "server" & !vm.graal.enabled &
+ *           vm.gc.Shenandoah
+ *
+ * @build compiler.c2.aarch64.TestVolatiles
+ *        compiler.c2.aarch64.TestVolatileLoad
+ *        compiler.c2.aarch64.TestUnsafeVolatileLoad
+ *        compiler.c2.aarch64.TestVolatileStore
+ *        compiler.c2.aarch64.TestUnsafeVolatileStore
+ *        compiler.c2.aarch64.TestUnsafeVolatileCAS
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestVolatileLoad Shenandoah
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestVolatileStore Shenandoah
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestUnsafeVolatileLoad Shenandoah
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestUnsafeVolatileStore Shenandoah
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestUnsafeVolatileCAS Shenandoah
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestVolatileLoad ShenandoahTraversal
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestVolatileStore ShenandoahTraversal
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestUnsafeVolatileLoad ShenandoahTraversal
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestUnsafeVolatileStore ShenandoahTraversal
+ *
+ * @run driver compiler.c2.aarch64.TestVolatilesSerial
+ *      TestUnsafeVolatileCAS ShenandoahTraversal
+ */
+
+package compiler.c2.aarch64;
+
+public class TestVolatilesShenandoah {
+    public static void main(String args[]) throws Throwable
+    {
+        // delegate work to shared code
+        new TestVolatiles().runtest(args[0], args[1]);
+    }
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/hotspot/jtreg/gc/startup_warnings/TestShenandoah.java	2020-01-17 17:15:18.680113476 +0100
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+* @test TestShenandoah
+* @key gc
+* @requires vm.gc.Shenandoah & !vm.graal.enabled
+* @bug 8006398
+* @summary Test that the Shenandoah collector does not print a warning message
+* @library /test/lib
+* @modules java.base/jdk.internal.misc
+*          java.management
+*/
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+
+public class TestShenandoah {
+
+  public static void main(String args[]) throws Exception {
+    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-XX:+UnlockExperimentalVMOptions", "-XX:+UseShenandoahGC", "-version");
+    OutputAnalyzer output = new OutputAnalyzer(pb.start());
+    output.shouldNotContain("deprecated");
+    output.shouldNotContain("error");
+    output.shouldHaveExitValue(0);
+  }
+
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithShenandoah.java	2020-01-17 17:15:19.277113443 +0100
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+import java.io.IOException;
+
+/*
+ * @test TestGCBasherWithShenandoah
+ * @key gc
+ * @key stress
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server" & !vm.emulatedClient & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive
+ *      -XX:+ShenandoahVerify -XX:+ShenandoahDegeneratedGC
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive
+ *      -XX:+ShenandoahVerify -XX:-ShenandoahDegeneratedGC
+ *      TestGCBasherWithShenandoah 120000
+ */
+
+/*
+ * @test TestGCBasherWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server" & !vm.emulatedClient & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahOOMDuringEvacALot
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahAllocFailureALot
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      TestGCBasherWithShenandoah 120000
+ */
+
+/*
+ * @test TestGCBasherWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server" & !vm.emulatedClient & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=adaptive
+ *      -XX:+ShenandoahVerify
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=adaptive
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=compact
+ *      TestGCBasherWithShenandoah 120000
+ */
+
+/*
+ * @test TestGCBasherWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server" & !vm.emulatedClient & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahOOMDuringEvacALot
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahAllocFailureALot
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal -XX:ShenandoahGCHeuristics=aggressive
+ *      TestGCBasherWithShenandoah 120000
+ */
+
+/*
+ * @test TestGCBasherWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @requires vm.flavor == "server" & !vm.emulatedClient & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal
+ *      -XX:+ShenandoahVerify
+ *      TestGCBasherWithShenandoah 120000
+ *
+ * @run main/othervm/timeout=200 -Xlog:gc*=info -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal
+ *      TestGCBasherWithShenandoah 120000
+ */
+public class TestGCBasherWithShenandoah {
+    public static void main(String[] args) throws IOException {
+        TestGCBasher.main(args);
+    }
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/hotspot/jtreg/gc/stress/gclocker/TestGCLockerWithShenandoah.java	2020-01-17 17:15:19.874113410 +0100
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/*
+ * @test TestGCLockerWithShenandoah
+ * @key gc
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Stress Shenandoah's JNI handling by calling GetPrimitiveArrayCritical while concurrently filling up old gen.
+ *
+ * @run main/native/othervm/timeout=200 -Xlog:gc*=info -Xms1500m -Xmx1500m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC
+ *      -XX:+ShenandoahVerify
+ *      TestGCLockerWithShenandoah
+ *
+ * @run main/native/othervm/timeout=200 -Xlog:gc*=info -Xms1500m -Xmx1500m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC
+ *      TestGCLockerWithShenandoah
+ *
+ * @run main/native/othervm/timeout=200 -Xlog:gc*=info -Xms1500m -Xmx1500m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahOOMDuringEvacALot
+ *      TestGCLockerWithShenandoah
+ *
+ * @run main/native/othervm/timeout=200 -Xlog:gc*=info -Xms1500m -Xmx1500m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahAllocFailureALot
+ *      TestGCLockerWithShenandoah
+ */
+public class TestGCLockerWithShenandoah {
+    public static void main(String[] args) {
+        String[] testArgs = {"2", "Shenandoah heap"};
+        TestGCLocker.main(testArgs);
+    }
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/hotspot/jtreg/gc/stress/gcold/TestGCOldWithShenandoah.java	2020-01-17 17:15:20.469113377 +0100
@@ -0,0 +1,125 @@
+/*
+* Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*/
+
+/*
+ * @test TestGCOldWithShenandoah
+ * @key gc
+ * @key stress
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Stress the GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive
+ *      -XX:+ShenandoahDegeneratedGC -XX:+ShenandoahVerify
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive
+ *      -XX:-ShenandoahDegeneratedGC -XX:+ShenandoahVerify
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive
+ *      -XX:+ShenandoahDegeneratedGC
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=passive
+ *      -XX:-ShenandoahDegeneratedGC
+ *      TestGCOld 50 1 20 10 10000
+ */
+
+/*
+ * @test TestGCOldWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Stress the GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahOOMDuringEvacALot
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahAllocFailureALot
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=adaptive
+ *      -XX:+ShenandoahVerify
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=adaptive
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=compact
+ *      TestGCOld 50 1 20 10 10000
+ */
+
+/*
+ * @test TestGCOldWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Stress the GC by trying to make old objects more likely to be garbage than young objects.
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahOOMDuringEvacALot
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal -XX:ShenandoahGCHeuristics=aggressive
+ *      -XX:+ShenandoahAllocFailureALot
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal -XX:ShenandoahGCHeuristics=aggressive
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm/timeout=600 -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal
+ *      -XX:+ShenandoahVerify
+ *      TestGCOld 50 1 20 10 10000
+ *
+ * @run main/othervm -Xmx384M -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal
+ *      TestGCOld 50 1 20 10 10000
+ */
+
+public class TestGCOldWithShenandoah {
+
+    public static void main(String[] args) {
+        TestGCOld.main(args);
+    }
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithShenandoah.java	2020-01-17 17:15:21.060113344 +0100
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/*
+ * @test TestSystemGCWithShenandoah
+ * @key gc
+ * @key stress
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC full GC by allocating objects of different lifetimes concurrently with System.gc().
+ *
+ * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC
+ *      -XX:+ShenandoahVerify
+ *      TestSystemGCWithShenandoah 270
+ *
+ * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC
+ *      TestSystemGCWithShenandoah 270
+ */
+
+/*
+ * @test TestSystemGCWithShenandoah
+ * @key gc
+ * @key stress
+ * @library /
+ * @requires vm.gc.Shenandoah & !vm.graal.enabled
+ * @summary Stress the Shenandoah GC full GC by allocating objects of different lifetimes concurrently with System.gc().
+ *
+ * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UnlockExperimentalVMOptions -XX:+UnlockDiagnosticVMOptions
+ *      -XX:+UseShenandoahGC -XX:ShenandoahGCMode=traversal
+ *      -XX:+ShenandoahVerify
+ *      TestSystemGCWithShenandoah 270
+ *
+ */
+public class TestSystemGCWithShenandoah {
+    public static void main(String[] args) throws Exception {
+        TestSystemGC.main(args);
+    }
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/jdk/jdk/jfr/event/gc/detailed/TestShenandoahHeapRegionInformationEvent.java	2020-01-17 17:15:21.653113312 +0100
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+package jdk.jfr.event.gc.detailed;
+
+import java.nio.file.Paths;
+import java.util.List;
+
+import jdk.jfr.EventType;
+import jdk.jfr.FlightRecorder;
+import jdk.jfr.Recording;
+import jdk.jfr.consumer.RecordedEvent;
+import jdk.test.lib.Asserts;
+import jdk.test.lib.jfr.EventNames;
+import jdk.test.lib.jfr.Events;
+import jdk.test.lib.jfr.GCHelper;
+
+/**
+ * @test
+ * @bug 8221507
+ * @requires vm.hasJFR
+ * @requires vm.gc == "Shenandoah" | vm.gc == null
+ * @key jfr
+ * @library /test/lib /test/jdk
+ * @run main/othervm  -Xmx32m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGarbageThreshold=1 jdk.jfr.event.gc.detailed.TestShenandoahHeapRegionInformationEvent
+ */
+
+
+public class TestShenandoahHeapRegionInformationEvent {
+    private final static String EVENT_NAME = EventNames.ShenandoahHeapRegionInformation;
+    public static void main(String[] args) throws Exception {
+        try (Recording recording = new Recording()) {
+            // activate the event we are interested in and start recording
+            for (EventType t : FlightRecorder.getFlightRecorder().getEventTypes()) {
+                System.out.println(t.getName());
+            }
+            recording.enable(EVENT_NAME);
+            recording.start();
+            recording.stop();
+
+            // Verify recording
+            List<RecordedEvent> events = Events.fromRecording(recording);
+            Events.hasEvents(events);
+            for (RecordedEvent event : events) {
+                Events.assertField(event, "index").notEqual(-1);
+                GCHelper.assertIsValidShenandoahHeapRegionState(Events.assertField(event, "state").getValue());
+                Events.assertField(event, "used").atMost(1L*1024*1024);
+            }
+        }
+    }
+}
--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/test/jdk/jdk/jfr/event/gc/detailed/TestShenandoahHeapRegionStateChangeEvent.java	2020-01-17 17:15:22.248113279 +0100
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+package jdk.jfr.event.gc.detailed;
+
+import java.nio.file.Paths;
+import java.time.Duration;
+import java.util.List;
+
+import jdk.jfr.Recording;
+import jdk.jfr.consumer.RecordedEvent;
+import jdk.test.lib.Asserts;
+import jdk.test.lib.jfr.EventNames;
+import jdk.test.lib.jfr.Events;
+import jdk.test.lib.jfr.GCHelper;
+
+/**
+ * @test
+ * @bug 8221507
+ * @requires vm.hasJFR
+ * @requires vm.gc == "Shenandoah" | vm.gc == null
+ * @key jfr
+ * @library /test/lib /test/jdk
+ * @run main/othervm  -Xmx32m -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:ShenandoahGarbageThreshold=1 jdk.jfr.event.gc.detailed.TestShenandoahHeapRegionStateChangeEvent
+ */
+
+public class TestShenandoahHeapRegionStateChangeEvent {
+    private final static String EVENT_NAME = EventNames.ShenandoahHeapRegionStateChange;
+
+    public static void main(String[] args) throws Exception {
+        try (Recording recording = new Recording()) {
+            // activate the event we are interested in and start recording
+            recording.enable(EVENT_NAME).withThreshold(Duration.ofMillis(0));
+            recording.start();
+
+            byte[][] array = new byte[1024][];
+            for (int i = 0; i < array.length; i++) {
+                array[i] = new byte[20 * 1024];
+            }
+            recording.stop();
+
+            // Verify recording
+            List<RecordedEvent> events = Events.fromRecording(recording);
+            Asserts.assertFalse(events.isEmpty(), "No events found");
+
+            for (RecordedEvent event : events) {
+                Events.assertField(event, "index").notEqual(-1);
+                GCHelper.assertIsValidShenandoahHeapRegionState(Events.assertField(event, "from").getValue());
+                GCHelper.assertIsValidShenandoahHeapRegionState(Events.assertField(event, "to").getValue());
+                Events.assertField(event, "used").atMost(1L*1024*1024);
+            }
+        }
+    }
+}