8248388: ZGC: Load barrier incorrectly elided in jdk/java/text/Format…

…/DateFormat/SDFTCKZoneNamesTest.java

Reviewed-by: kvn, thartmann

src/hotspot/share/opto/arraycopynode.hpp

@@ -112,8 +112,9 @@ class ArrayCopyNode : public CallNode {
   bool finish_transform(PhaseGVN *phase, bool can_reshape,
                         Node* ctl, Node *mem);
   static bool may_modify_helper(const TypeOopPtr *t_oop, Node* n, PhaseTransform *phase, CallNode*& call);
-
+public:
   static Node* load(BarrierSetC2* bs, PhaseGVN *phase, Node*& ctl, MergeMemNode* mem, Node* addr, const TypePtr* adr_type, const Type *type, BasicType bt);
+private:
   void store(BarrierSetC2* bs, PhaseGVN *phase, Node*& ctl, MergeMemNode* mem, Node* addr, const TypePtr* adr_type, Node* val, const Type *type, BasicType bt);
 
 public:
@@ -153,7 +154,7 @@ class ArrayCopyNode : public CallNode {
   bool is_clone_array()           const  { assert(_kind != None, "should bet set"); return _kind == CloneArray; }
   // is_clone_oop_array is used when oop arrays need GC barriers
   bool is_clone_oop_array()       const  { assert(_kind != None, "should bet set"); return _kind == CloneOopArray; }
-  // is_clonebasic - is true for any type of clone that doesn't need a barrier.
+  // is_clonebasic - is true for any type of clone that doesn't need a writebarrier.
   bool is_clonebasic()            const  { assert(_kind != None, "should bet set"); return _kind == CloneInst || _kind == CloneArray; }
   bool is_copyof()                const  { assert(_kind != None, "should bet set"); return _kind == CopyOf; }
   bool is_copyof_validated()      const  { assert(_kind != None, "should bet set"); return _kind == CopyOf && _arguments_validated; }

src/hotspot/share/opto/macro.cpp

@@ -367,7 +367,9 @@ Node* PhaseMacroExpand::make_arraycopy_load(ArrayCopyNode* ac, intptr_t offset,
     Node* base = ac->in(ArrayCopyNode::Src);
     Node* adr = _igvn.transform(new AddPNode(base, base, MakeConX(offset)));
     const TypePtr* adr_type = _igvn.type(base)->is_ptr()->add_offset(offset);
-    res = LoadNode::make(_igvn, ctl, mem, adr, adr_type, type, bt, MemNode::unordered, LoadNode::UnknownControl);
+    MergeMemNode* mergemen = MergeMemNode::make(mem);
+    BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+    res = ArrayCopyNode::load(bs, &_igvn, ctl, mergemen, adr, adr_type, type, bt);
   } else {
     if (ac->modifies(offset, offset, &_igvn, true)) {
       assert(ac->in(ArrayCopyNode::Dest) == alloc->result_cast(), "arraycopy destination should be allocation's result");
@@ -405,11 +407,12 @@ Node* PhaseMacroExpand::make_arraycopy_load(ArrayCopyNode* ac, intptr_t offset,
           return NULL;
         }
       }
-      res = LoadNode::make(_igvn, ctl, mem, adr, adr_type, type, bt, MemNode::unordered, LoadNode::UnknownControl);
+      MergeMemNode* mergemen = MergeMemNode::make(mem);
+      BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+      res = ArrayCopyNode::load(bs, &_igvn, ctl, mergemen, adr, adr_type, type, bt);
     }
   }
   if (res != NULL) {
-    res = _igvn.transform(res);
     if (ftype->isa_narrowoop()) {
       // PhaseMacroExpand::scalar_replacement adds DecodeN nodes
       res = _igvn.transform(new EncodePNode(res, ftype));