6667580: Optimize CmpP for allocations

Summary: CmpP could be optimized out if it compares new allocated objects.
Reviewed-by: jrose, never, rasbold

src/share/vm/includeDB_compiler2

@@ -990,6 +990,7 @@ stubRoutines.cpp                        runtime.hpp
 
 subnode.cpp                             addnode.hpp
 subnode.cpp                             allocation.inline.hpp
+subnode.cpp                             callnode.hpp
 subnode.cpp                             cfgnode.hpp
 subnode.cpp                             compileLog.hpp
 subnode.cpp                             connode.hpp

src/share/vm/opto/callnode.hpp

@@ -91,7 +91,9 @@ public:
 class ParmNode : public ProjNode {
   static const char * const names[TypeFunc::Parms+1];
 public:
-  ParmNode( StartNode *src, uint con ) : ProjNode(src,con) {}
+  ParmNode( StartNode *src, uint con ) : ProjNode(src,con) {
+    init_class_id(Class_Parm);
+  }
   virtual int Opcode() const;
   virtual bool  is_CFG() const { return (_con == TypeFunc::Control); }
   virtual uint ideal_reg() const;

src/share/vm/opto/memnode.hpp

@@ -60,13 +60,13 @@ protected:
     debug_only(_adr_type=at; adr_type();)
   }
 
+public:
   // Helpers for the optimizer.  Documented in memnode.cpp.
   static bool detect_ptr_independence(Node* p1, AllocateNode* a1,
                                       Node* p2, AllocateNode* a2,
                                       PhaseTransform* phase);
   static bool adr_phi_is_loop_invariant(Node* adr_phi, Node* cast);
 
-public:
   // This one should probably be a phase-specific function:
   static bool detect_dominating_control(Node* dom, Node* sub);
 

src/share/vm/opto/node.hpp

@@ -91,6 +91,7 @@ class Node_List;
 class Node_Stack;
 class NullCheckNode;
 class OopMap;
+class ParmNode;
 class PCTableNode;
 class PhaseCCP;
 class PhaseGVN;
@@ -557,6 +558,7 @@ public:
       DEFINE_CLASS_ID(JumpProj,  Proj, 1)
       DEFINE_CLASS_ID(IfTrue,    Proj, 2)
       DEFINE_CLASS_ID(IfFalse,   Proj, 3)
+      DEFINE_CLASS_ID(Parm,      Proj, 4)
 
     DEFINE_CLASS_ID(Region, Node, 3)
       DEFINE_CLASS_ID(Loop, Region, 0)
@@ -712,6 +714,7 @@ public:
   DEFINE_CLASS_QUERY(Mul)
   DEFINE_CLASS_QUERY(Multi)
   DEFINE_CLASS_QUERY(MultiBranch)
+  DEFINE_CLASS_QUERY(Parm)
   DEFINE_CLASS_QUERY(PCTable)
   DEFINE_CLASS_QUERY(Phi)
   DEFINE_CLASS_QUERY(Proj)

src/share/vm/opto/subnode.cpp

@@ -614,6 +614,13 @@ const Type *CmpPNode::sub( const Type *t1, const Type *t2 ) const {
   const TypeOopPtr* p0 = r0->isa_oopptr();
   const TypeOopPtr* p1 = r1->isa_oopptr();
   if (p0 && p1) {
+    Node* in1 = in(1)->uncast();
+    Node* in2 = in(2)->uncast();
+    AllocateNode* alloc1 = AllocateNode::Ideal_allocation(in1, NULL);
+    AllocateNode* alloc2 = AllocateNode::Ideal_allocation(in2, NULL);
+    if (MemNode::detect_ptr_independence(in1, alloc1, in2, alloc2, NULL)) {
+      return TypeInt::CC_GT;  // different pointers
+    }
     ciKlass* klass0 = p0->klass();
     bool    xklass0 = p0->klass_is_exact();
     ciKlass* klass1 = p1->klass();