--- /dev/null	2020-02-06 11:34:07.664987501 +0100
+++ new/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp	2020-02-06 19:19:14.333544120 +0100
@@ -0,0 +1,264 @@
+/*
+ * Copyright (c) 2015, 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.
+ *
+ */
+
+#ifndef SHARE_GC_SHENANDOAH_C2_SHENANDOAHSUPPORT_HPP
+#define SHARE_GC_SHENANDOAH_C2_SHENANDOAHSUPPORT_HPP
+
+#include "memory/allocation.hpp"
+#include "opto/addnode.hpp"
+#include "opto/graphKit.hpp"
+#include "opto/machnode.hpp"
+#include "opto/memnode.hpp"
+#include "opto/multnode.hpp"
+#include "opto/node.hpp"
+
+class PhaseGVN;
+class MemoryGraphFixer;
+
+class ShenandoahBarrierC2Support : public AllStatic {
+private:
+#ifdef ASSERT
+  enum verify_type {
+    ShenandoahLoad,
+    ShenandoahStore,
+    ShenandoahValue,
+    ShenandoahOopStore,
+    ShenandoahNone
+  };
+
+  static bool verify_helper(Node* in, Node_Stack& phis, VectorSet& visited, verify_type t, bool trace, Unique_Node_List& barriers_used);
+  static void report_verify_failure(const char* msg, Node* n1 = NULL, Node* n2 = NULL);
+  static void verify_raw_mem(RootNode* root);
+#endif
+  static Node* dom_mem(Node* mem, Node* ctrl, int alias, Node*& mem_ctrl, PhaseIdealLoop* phase);
+  static Node* no_branches(Node* c, Node* dom, bool allow_one_proj, PhaseIdealLoop* phase);
+  static bool is_heap_state_test(Node* iff, int mask);
+  static bool try_common_gc_state_load(Node *n, PhaseIdealLoop *phase);
+  static bool has_safepoint_between(Node* start, Node* stop, PhaseIdealLoop *phase);
+  static Node* find_bottom_mem(Node* ctrl, PhaseIdealLoop* phase);
+  static void follow_barrier_uses(Node* n, Node* ctrl, Unique_Node_List& uses, PhaseIdealLoop* phase);
+  static void test_null(Node*& ctrl, Node* val, Node*& null_ctrl, PhaseIdealLoop* phase);
+  static void test_heap_stable(Node*& ctrl, Node* raw_mem, Node*& heap_stable_ctrl,
+                               PhaseIdealLoop* phase);
+  static void call_lrb_stub(Node*& ctrl, Node*& val, Node* load_addr, Node*& result_mem, Node* raw_mem, bool is_native, PhaseIdealLoop* phase);
+  static Node* clone_null_check(Node*& c, Node* val, Node* unc_ctrl, PhaseIdealLoop* phase);
+  static void fix_null_check(Node* unc, Node* unc_ctrl, Node* new_unc_ctrl, Unique_Node_List& uses,
+                             PhaseIdealLoop* phase);
+  static void in_cset_fast_test(Node*& ctrl, Node*& not_cset_ctrl, Node* val, Node* raw_mem, PhaseIdealLoop* phase);
+  static void move_heap_stable_test_out_of_loop(IfNode* iff, PhaseIdealLoop* phase);
+  static void merge_back_to_back_tests(Node* n, PhaseIdealLoop* phase);
+  static bool identical_backtoback_ifs(Node *n, PhaseIdealLoop* phase);
+  static void fix_ctrl(Node* barrier, Node* region, const MemoryGraphFixer& fixer, Unique_Node_List& uses, Unique_Node_List& uses_to_ignore, uint last, PhaseIdealLoop* phase);
+  static IfNode* find_unswitching_candidate(const IdealLoopTree *loop, PhaseIdealLoop* phase);
+
+  static Node* get_load_addr(PhaseIdealLoop* phase, VectorSet& visited, Node* lrb);
+public:
+  static bool is_dominator(Node* d_c, Node* n_c, Node* d, Node* n, PhaseIdealLoop* phase);
+  static bool is_dominator_same_ctrl(Node* c, Node* d, Node* n, PhaseIdealLoop* phase);
+
+  static bool is_gc_state_load(Node* n);
+  static bool is_heap_stable_test(Node* iff);
+
+  static bool expand(Compile* C, PhaseIterGVN& igvn);
+  static void pin_and_expand(PhaseIdealLoop* phase);
+  static void optimize_after_expansion(VectorSet& visited, Node_Stack& nstack, Node_List& old_new, PhaseIdealLoop* phase);
+
+#ifdef ASSERT
+  static void verify(RootNode* root);
+#endif
+};
+
+class ShenandoahEnqueueBarrierNode : public Node {
+public:
+  ShenandoahEnqueueBarrierNode(Node* val);
+
+  const Type *bottom_type() const;
+  const Type* Value(PhaseGVN* phase) const;
+  Node* Identity(PhaseGVN* phase);
+
+  int Opcode() const;
+
+private:
+  enum { Needed, NotNeeded, MaybeNeeded };
+
+  static int needed(Node* n);
+  static Node* next(Node* n);
+};
+
+class MemoryGraphFixer : public ResourceObj {
+private:
+  Node_List _memory_nodes;
+  int _alias;
+  PhaseIdealLoop* _phase;
+  bool _include_lsm;
+
+  void collect_memory_nodes();
+  Node* get_ctrl(Node* n) const;
+  Node* ctrl_or_self(Node* n) const;
+  bool mem_is_valid(Node* m, Node* c) const;
+  MergeMemNode* allocate_merge_mem(Node* mem, Node* rep_proj, Node* rep_ctrl) const;
+  MergeMemNode* clone_merge_mem(Node* u, Node* mem, Node* rep_proj, Node* rep_ctrl, DUIterator& i) const;
+  void fix_memory_uses(Node* mem, Node* replacement, Node* rep_proj, Node* rep_ctrl) const;
+  bool should_process_phi(Node* phi) const;
+  bool has_mem_phi(Node* region) const;
+
+public:
+  MemoryGraphFixer(int alias, bool include_lsm, PhaseIdealLoop* phase) :
+    _alias(alias), _phase(phase), _include_lsm(include_lsm) {
+    assert(_alias != Compile::AliasIdxBot, "unsupported");
+    collect_memory_nodes();
+  }
+
+  Node* find_mem(Node* ctrl, Node* n) const;
+  void fix_mem(Node* ctrl, Node* region, Node* mem, Node* mem_for_ctrl, Node* mem_phi, Unique_Node_List& uses);
+  int alias() const { return _alias; }
+};
+
+class ShenandoahCompareAndSwapPNode : public CompareAndSwapPNode {
+public:
+  ShenandoahCompareAndSwapPNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord)
+    : CompareAndSwapPNode(c, mem, adr, val, ex, mem_ord) { }
+
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape) {
+    if (in(ExpectedIn) != NULL && phase->type(in(ExpectedIn)) == TypePtr::NULL_PTR) {
+      return new CompareAndSwapPNode(in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), in(MemNode::ValueIn), in(ExpectedIn), order());
+    }
+    return NULL;
+  }
+
+  virtual int Opcode() const;
+};
+
+class ShenandoahCompareAndSwapNNode : public CompareAndSwapNNode {
+public:
+  ShenandoahCompareAndSwapNNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord)
+    : CompareAndSwapNNode(c, mem, adr, val, ex, mem_ord) { }
+
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape) {
+    if (in(ExpectedIn) != NULL && phase->type(in(ExpectedIn)) == TypeNarrowOop::NULL_PTR) {
+      return new CompareAndSwapNNode(in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), in(MemNode::ValueIn), in(ExpectedIn), order());
+    }
+    return NULL;
+  }
+
+  virtual int Opcode() const;
+};
+
+class ShenandoahWeakCompareAndSwapPNode : public WeakCompareAndSwapPNode {
+public:
+  ShenandoahWeakCompareAndSwapPNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord)
+    : WeakCompareAndSwapPNode(c, mem, adr, val, ex, mem_ord) { }
+
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape) {
+    if (in(ExpectedIn) != NULL && phase->type(in(ExpectedIn)) == TypePtr::NULL_PTR) {
+      return new WeakCompareAndSwapPNode(in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), in(MemNode::ValueIn), in(ExpectedIn), order());
+    }
+    return NULL;
+  }
+
+  virtual int Opcode() const;
+};
+
+class ShenandoahWeakCompareAndSwapNNode : public WeakCompareAndSwapNNode {
+public:
+  ShenandoahWeakCompareAndSwapNNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex, MemNode::MemOrd mem_ord)
+    : WeakCompareAndSwapNNode(c, mem, adr, val, ex, mem_ord) { }
+
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape) {
+    if (in(ExpectedIn) != NULL && phase->type(in(ExpectedIn)) == TypeNarrowOop::NULL_PTR) {
+      return new WeakCompareAndSwapNNode(in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), in(MemNode::ValueIn), in(ExpectedIn), order());
+    }
+    return NULL;
+  }
+
+  virtual int Opcode() const;
+};
+
+class ShenandoahCompareAndExchangePNode : public CompareAndExchangePNode {
+public:
+  ShenandoahCompareAndExchangePNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, const Type* t, MemNode::MemOrd mem_ord)
+    : CompareAndExchangePNode(c, mem, adr, val, ex, at, t, mem_ord) { }
+
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape) {
+    if (in(ExpectedIn) != NULL && phase->type(in(ExpectedIn)) == TypePtr::NULL_PTR) {
+      return new CompareAndExchangePNode(in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), in(MemNode::ValueIn), in(ExpectedIn), adr_type(), bottom_type(), order());
+    }
+    return NULL;
+  }
+
+  virtual int Opcode() const;
+};
+
+class ShenandoahCompareAndExchangeNNode : public CompareAndExchangeNNode {
+public:
+  ShenandoahCompareAndExchangeNNode(Node *c, Node *mem, Node *adr, Node *val, Node *ex, const TypePtr* at, const Type* t, MemNode::MemOrd mem_ord)
+    : CompareAndExchangeNNode(c, mem, adr, val, ex, at, t, mem_ord) { }
+
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape) {
+    if (in(ExpectedIn) != NULL && phase->type(in(ExpectedIn)) == TypeNarrowOop::NULL_PTR) {
+      return new CompareAndExchangeNNode(in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), in(MemNode::ValueIn), in(ExpectedIn), adr_type(), bottom_type(), order());
+    }
+    return NULL;
+  }
+
+  virtual int Opcode() const;
+};
+
+class ShenandoahLoadReferenceBarrierNode : public Node {
+public:
+  enum {
+    Control,
+    ValueIn
+  };
+
+  enum Strength {
+    NONE, STRONG
+  };
+
+  ShenandoahLoadReferenceBarrierNode(Node* ctrl, Node* val);
+
+  virtual int Opcode() const;
+  virtual const Type* bottom_type() const;
+  virtual const Type* Value(PhaseGVN* phase) const;
+  virtual const class TypePtr *adr_type() const { return TypeOopPtr::BOTTOM; }
+  virtual uint match_edge(uint idx) const {
+    return idx >= ValueIn;
+  }
+  virtual uint ideal_reg() const { return Op_RegP; }
+
+  virtual Node* Identity(PhaseGVN* phase);
+
+  uint size_of() const {
+    return sizeof(*this);
+  }
+
+  Strength get_barrier_strength();
+  CallStaticJavaNode* pin_and_expand_null_check(PhaseIterGVN& igvn);
+
+private:
+  bool needs_barrier(PhaseGVN* phase, Node* n);
+  bool needs_barrier_impl(PhaseGVN* phase, Node* n, Unique_Node_List &visited);
+};
+
+
+#endif // SHARE_GC_SHENANDOAH_C2_SHENANDOAHSUPPORT_HPP