992     return NULL;
 993   }
 994 #endif
 995 
 996   // Replace dominated IfNode
 997   dominated_by( prev_dom, igvn );
 998 
 999   // Must return either the original node (now dead) or a new node
1000   // (Do not return a top here, since that would break the uniqueness of top.)
1001   return new (phase->C, 1) ConINode(TypeInt::ZERO);
1002 }
1003 
1004 //------------------------------dominated_by-----------------------------------
1005 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) {
1006   igvn->hash_delete(this);      // Remove self to prevent spurious V-N
1007   Node *idom = in(0);
1008   // Need opcode to decide which way 'this' test goes
1009   int prev_op = prev_dom->Opcode();
1010   Node *top = igvn->C->top(); // Shortcut to top
1011 







1012   // Now walk the current IfNode's projections.
1013   // Loop ends when 'this' has no more uses.
1014   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1015     Node *ifp = last_out(i);     // Get IfTrue/IfFalse
1016     igvn->add_users_to_worklist(ifp);
1017     // Check which projection it is and set target.
1018     // Data-target is either the dominating projection of the same type
1019     // or TOP if the dominating projection is of opposite type.
1020     // Data-target will be used as the new control edge for the non-CFG
1021     // nodes like Casts and Loads.
1022     Node *data_target = (ifp->Opcode() == prev_op ) ? prev_dom : top;
1023     // Control-target is just the If's immediate dominator or TOP.
1024     Node *ctrl_target = (ifp->Opcode() == prev_op ) ?     idom : top;
1025 
1026     // For each child of an IfTrue/IfFalse projection, reroute.
1027     // Loop ends when projection has no more uses.
1028     for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1029       Node* s = ifp->last_out(j);   // Get child of IfTrue/IfFalse
1030       igvn->hash_delete(s);         // Yank from hash table before edge hacking
1031       if( !s->depends_only_on_test() ) {
1032         // Find the control input matching this def-use edge.
1033         // For Regions it may not be in slot 0.
1034         uint l;
1035         for( l = 0; s->in(l) != ifp; l++ ) { }
1036         s->set_req(l, ctrl_target);
1037       } else {                      // Else, for control producers,
1038         s->set_req(0, data_target); // Move child to data-target
1039       }
1040       igvn->_worklist.push(s);  // Revisit collapsed Phis
1041     } // End for each child of a projection
1042 
1043     igvn->remove_dead_node(ifp);
1044   } // End for each IfTrue/IfFalse child of If

 992     return NULL;
 993   }
 994 #endif
 995 
 996   // Replace dominated IfNode
 997   dominated_by( prev_dom, igvn );
 998 
 999   // Must return either the original node (now dead) or a new node
1000   // (Do not return a top here, since that would break the uniqueness of top.)
1001   return new (phase->C, 1) ConINode(TypeInt::ZERO);
1002 }
1003 
1004 //------------------------------dominated_by-----------------------------------
1005 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) {
1006   igvn->hash_delete(this);      // Remove self to prevent spurious V-N
1007   Node *idom = in(0);
1008   // Need opcode to decide which way 'this' test goes
1009   int prev_op = prev_dom->Opcode();
1010   Node *top = igvn->C->top(); // Shortcut to top
1011 
1012   // Loop predicates may have depending checks which should not
1013   // be skipped. For example, range check predicate has two checks
1014   // for lower and upper bounds.
1015   ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
1016   if (PhaseIdealLoop::is_uncommon_trap_proj(unc_proj, Deoptimization::Reason_predicate))
1017     prev_dom = idom;
1018 
1019   // Now walk the current IfNode's projections.
1020   // Loop ends when 'this' has no more uses.
1021   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1022     Node *ifp = last_out(i);     // Get IfTrue/IfFalse
1023     igvn->add_users_to_worklist(ifp);
1024     // Check which projection it is and set target.
1025     // Data-target is either the dominating projection of the same type
1026     // or TOP if the dominating projection is of opposite type.
1027     // Data-target will be used as the new control edge for the non-CFG
1028     // nodes like Casts and Loads.
1029     Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1030     // Control-target is just the If's immediate dominator or TOP.
1031     Node *ctrl_target = (ifp->Opcode() == prev_op) ?     idom : top;
1032 
1033     // For each child of an IfTrue/IfFalse projection, reroute.
1034     // Loop ends when projection has no more uses.
1035     for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1036       Node* s = ifp->last_out(j);   // Get child of IfTrue/IfFalse
1037       igvn->hash_delete(s);         // Yank from hash table before edge hacking
1038       if( !s->depends_only_on_test() ) {
1039         // Find the control input matching this def-use edge.
1040         // For Regions it may not be in slot 0.
1041         uint l;
1042         for( l = 0; s->in(l) != ifp; l++ ) { }
1043         s->set_req(l, ctrl_target);
1044       } else {                      // Else, for control producers,
1045         s->set_req(0, data_target); // Move child to data-target
1046       }
1047       igvn->_worklist.push(s);  // Revisit collapsed Phis
1048     } // End for each child of a projection
1049 
1050     igvn->remove_dead_node(ifp);
1051   } // End for each IfTrue/IfFalse child of If