src/share/vm/opto/escape.cpp

rev 2892 : 7121140: Allocation paths require explicit memory synchronization operations for RMO systems
Summary: adds store store barrier after initialization of header and body of objects.
Reviewed-by:

*** 1593,1602 ****
--- 1593,1603 ----
    }
  
    GrowableArray<Node*> alloc_worklist;
    GrowableArray<Node*> addp_worklist;
    GrowableArray<Node*> ptr_cmp_worklist;
+   GrowableArray<Node*> storestore_worklist;
    PhaseGVN* igvn = _igvn;
  
    // Push all useful nodes onto CG list and set their type.
    for( uint next = 0; next < worklist_init.size(); ++next ) {
      Node* n = worklist_init.at(next);
*** 1616,1625 ****
--- 1617,1631 ----
        _mergemem_worklist.append(n->as_MergeMem());
      } else if (OptimizePtrCompare && n->is_Cmp() &&
                 (n->Opcode() == Op_CmpP || n->Opcode() == Op_CmpN)) {
        // Compare pointers nodes
        ptr_cmp_worklist.append(n);
+     } else if (n->is_MemBarStoreStore()) {
+       // Collect all MemBarStoreStore nodes so that depending on the
+       // escape status of the associated Allocate node some of them
+       // may be eliminated.
+       storestore_worklist.append(n);
      }
      for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
        Node* m = n->fast_out(i);   // Get user
        worklist_init.push(m);
      }
*** 1722,1736 ****
  
    // 6. Find fields initializing values for not escaped allocations
    uint alloc_length = alloc_worklist.length();
    for (uint next = 0; next < alloc_length; ++next) {
      Node* n = alloc_worklist.at(next);
!     if (ptnode_adr(n->_idx)->escape_state() == PointsToNode::NoEscape) {
        has_non_escaping_obj = true;
        if (n->is_Allocate()) {
          find_init_values(n, &visited, igvn);
!       }
      }
    }
  
    uint cg_length = cg_worklist.length();
  
--- 1728,1751 ----
  
    // 6. Find fields initializing values for not escaped allocations
    uint alloc_length = alloc_worklist.length();
    for (uint next = 0; next < alloc_length; ++next) {
      Node* n = alloc_worklist.at(next);
!     PointsToNode::EscapeState es = ptnode_adr(n->_idx)->escape_state();
!     if (es == PointsToNode::NoEscape) {
        has_non_escaping_obj = true;
        if (n->is_Allocate()) {
          find_init_values(n, &visited, igvn);
!         // The object allocated by this Allocate node will never be
!         // seen by an other thread. Mark it so that when it is
!         // expanded no MemBarStoreStore is added.
!         n->as_Allocate()->initialization()->set_does_not_escape();
!       }
!     } else if ((es == PointsToNode::ArgEscape) && n->is_Allocate()) {
!       // Same as above. Mark this Allocate node so that when it is
!       // expanded no MemBarStoreStore is added.
!       n->as_Allocate()->initialization()->set_does_not_escape();
      }
    }
  
    uint cg_length = cg_worklist.length();
  
*** 1872,1881 ****
--- 1887,1915 ----
        igvn->hash_delete(_pcmp_neq);
      if (_pcmp_eq->outcnt()  == 0)
        igvn->hash_delete(_pcmp_eq);
    }
  
+   // For MemBarStoreStore nodes added in library_call.cpp, check
+   // escape status of associated AllocateNode and optimize out
+   // MemBarStoreStore node if the allocated object never escapes.
+   while (storestore_worklist.length() != 0) {
+     Node *n = storestore_worklist.pop();
+     MemBarStoreStoreNode *storestore = n ->as_MemBarStoreStore();
+     Node *alloc = storestore->in(MemBarNode::Precedent)->in(0);
+     assert (alloc->is_Allocate(), "storestore should point to AllocateNode");
+     PointsToNode::EscapeState es = ptnode_adr(alloc->_idx)->escape_state();
+     if (es == PointsToNode::NoEscape || es == PointsToNode::ArgEscape) {
+       MemBarNode* mb = MemBarNode::make(C, Op_MemBarCPUOrder, Compile::AliasIdxBot);
+       mb->init_req(TypeFunc::Memory, storestore->in(TypeFunc::Memory));
+       mb->init_req(TypeFunc::Control, storestore->in(TypeFunc::Control));
+         
+       _igvn->register_new_node_with_optimizer(mb);
+       _igvn->replace_node(storestore, mb);
+     }
+   }
+ 
  #ifndef PRODUCT
    if (PrintEscapeAnalysis) {
      dump(); // Dump ConnectionGraph
    }
  #endif