*** old/src/share/vm/opto/connode.cpp	Wed Apr 29 10:32:35 2009
--- new/src/share/vm/opto/connode.cpp	Wed Apr 29 10:32:35 2009

*** 117,129 ****
--- 117,152 ----
      }
    }
    return NULL;
  }
  
+ //-----------------------------is_float_or_double_zero-----------------------
+ // Helper function for is_cmove_id to find float or double constant 0.0
+ bool CMoveNode::is_float_or_double_zero(PhaseTransform* phase, Node *val) {
+   const Type* t = phase->type(val);
+   if (t == Type::TOP) return false;
+   const TypeF *tf = t->isa_float_constant();
+   if( tf != NULL &&  tf->_f==0.0)
+     return true;
+   const TypeD *td = t->isa_double_constant();
+   if( td != NULL &&  td->_d==0.0)
+     return true;
+ 
+   return false;
+ }
+ 
  //------------------------------is_cmove_id------------------------------------
  // Helper function to check for CMOVE identity.  Shared with PhiNode::Identity
  Node *CMoveNode::is_cmove_id( PhaseTransform *phase, Node *cmp, Node *t, Node *f, BoolNode *b ) {
+   // Give up this identity check if either "t" or "f" is 0.0 (or -0.0)
+   // For example, for (f==0.0)?0.0:f, and if f = -0.0, the result should be 0.0 instead of -0.0(f)
+   // NOTE: non-constant double or float may still turn out to be 0.0 (-0.0). However, it may be
+   //       too expensive to disable this optimization for general cases.
+   if( is_float_or_double_zero(phase, t) ||
+       is_float_or_double_zero(phase, f) )
+     return NULL;
+ 
    // Check for Cmp'ing and CMove'ing same values
    if( (phase->eqv(cmp->in(1),f) &&
         phase->eqv(cmp->in(2),t)) ||
        // Swapped Cmp is OK
        (phase->eqv(cmp->in(2),f) &&