src/share/vm/opto/gcm.cpp

rev 8016 : 8069191: moving predicate out of loops may cause array accesses to bypass null check
Summary: Remove CastPP nodes only during final graph reshape
Reviewed-by:

*** 98,107 ****
--- 98,110 ----
      }
      n->set_req(0, pb->_succs[j]->head());
    }
  }
  
+ static bool is_dominator(Block* d, Block* n) {
+   return d->dom_lca(n) == d;
+ }
  
  //------------------------------schedule_pinned_nodes--------------------------
  // Set the basic block for Nodes pinned into blocks
  void PhaseCFG::schedule_pinned_nodes(VectorSet &visited) {
    // Allocate node stack of size C->unique()+8 to avoid frequent realloc
*** 120,129 ****
--- 123,162 ----
          }
          Block* block = get_block_for_node(input); // Basic block of controlling input
          schedule_node_into_block(node, block);
        }
  
+       // If the node has precedence edges (added when CastPP nodes are
+       // removed in final_graph_reshaping), fix the control of the
+       // node to cover the precedence edges and remove the
+       // dependencies.
+       Node* n = NULL;
+       for (uint i = node->len()-1; i >= node->req(); i--) {
+         Node* m = node->in(i);
+         if (m == NULL) continue;
+         // See Compile::final_graph_reshaping_impl(): we expect a test
+         // or a Region here.
+         if (m->is_block_proj() || m->is_block_start()) {
+           node->rm_prec(i);
+           if (n == NULL) {
+             n = m;
+           } else {
+             Block* bn = get_block_for_node(n);
+             Block* bm = get_block_for_node(m);
+             n = is_dominator(bn, bm) ? m : n;
+           }
+         }
+       }
+       if (n != NULL) {
+         assert(node->in(0), "control should have been set");
+         Block* bn = get_block_for_node(n);
+         Block* bnode = get_block_for_node(node->in(0));
+         if (!is_dominator(bn, bnode)) {
+           node->set_req(0, n);
+         }
+       }
+ 
        // process all inputs that are non NULL
        for (int i = node->req() - 1; i >= 0; --i) {
          if (node->in(i) != NULL) {
            spstack.push(node->in(i));
          }