8254269: simplify Node::disconnect_inputs

Node::disconnect_inputs cuts off all input edges without exception.

Reviewed-by: redestad, kvn

src/hotspot/share/opto/callGenerator.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -429,7 +429,7 @@ void LateInlineCallGenerator::do_late_inline() {
     // This check is done here because for_method_handle_inline() method
     // needs jvms for inlined state.
     if (!do_late_inline_check(jvms)) {
-      map->disconnect_inputs(NULL, C);
+      map->disconnect_inputs(C);
       return;
     }
 

src/hotspot/share/opto/compile.cpp

@@ -2772,7 +2772,7 @@ void Compile::eliminate_redundant_card_marks(Node* n) {
         // Eliminate the previous StoreCM
         prev->set_req(MemNode::Memory, mem->in(MemNode::Memory));
         assert(mem->outcnt() == 0, "should be dead");
-        mem->disconnect_inputs(NULL, this);
+        mem->disconnect_inputs(this);
       } else {
         prev = mem;
       }
@@ -3054,7 +3054,7 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
           n->set_req(AddPNode::Base, nn);
           n->set_req(AddPNode::Address, nn);
           if (addp->outcnt() == 0) {
-            addp->disconnect_inputs(NULL, this);
+            addp->disconnect_inputs(this);
           }
         }
       }
@@ -3127,12 +3127,12 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
 
       n->subsume_by(new_in1, this);
       if (in1->outcnt() == 0) {
-        in1->disconnect_inputs(NULL, this);
+        in1->disconnect_inputs(this);
       }
     } else {
       n->subsume_by(n->in(1), this);
       if (n->outcnt() == 0) {
-        n->disconnect_inputs(NULL, this);
+        n->disconnect_inputs(this);
       }
     }
     break;
@@ -3210,10 +3210,10 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
         Node* cmpN = new CmpNNode(in1->in(1), new_in2);
         n->subsume_by(cmpN, this);
         if (in1->outcnt() == 0) {
-          in1->disconnect_inputs(NULL, this);
+          in1->disconnect_inputs(this);
         }
         if (in2->outcnt() == 0) {
-          in2->disconnect_inputs(NULL, this);
+          in2->disconnect_inputs(this);
         }
       }
     }
@@ -3244,7 +3244,7 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
       }
     }
     if (in1->outcnt() == 0) {
-      in1->disconnect_inputs(NULL, this);
+      in1->disconnect_inputs(this);
     }
     break;
   }
@@ -3410,7 +3410,7 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
         }
       }
       if (in2->outcnt() == 0) { // Remove dead node
-        in2->disconnect_inputs(NULL, this);
+        in2->disconnect_inputs(this);
       }
     }
     break;
@@ -3442,7 +3442,7 @@ void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& f
               wq.push(in);
             }
           }
-          m->disconnect_inputs(NULL, this);
+          m->disconnect_inputs(this);
         }
       }
     }
@@ -3585,7 +3585,7 @@ void Compile::final_graph_reshaping_walk( Node_Stack &nstack, Node *root, Final_
           n->set_req(j, in->in(1));
         }
         if (in->outcnt() == 0) {
-          in->disconnect_inputs(NULL, this);
+          in->disconnect_inputs(this);
         }
       }
     }

src/hotspot/share/opto/graphKit.cpp

@@ -163,7 +163,7 @@ void GraphKit::verify_exception_state(SafePointNode* ex_map) {
 void GraphKit::stop_and_kill_map() {
   SafePointNode* dead_map = stop();
   if (dead_map != NULL) {
-    dead_map->disconnect_inputs(NULL, C); // Mark the map as killed.
+    dead_map->disconnect_inputs(C); // Mark the map as killed.
     assert(dead_map->is_killed(), "must be so marked");
   }
 }
@@ -1960,7 +1960,7 @@ void GraphKit::replace_call(CallNode* call, Node* result, bool do_replaced_nodes
   }
 
   // Disconnect the call from the graph
-  call->disconnect_inputs(NULL, C);
+  call->disconnect_inputs(C);
   C->gvn_replace_by(call, C->top());
 
   // Clean up any MergeMems that feed other MergeMems since the

src/hotspot/share/opto/ifg.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -616,7 +616,7 @@ bool PhaseChaitin::remove_node_if_not_used(Block* b, uint location, Node* n, uin
     if (lrg._def == n) {
       lrg._def = 0;
     }
-    n->disconnect_inputs(NULL, C);
+    n->disconnect_inputs(C);
     _cfg.unmap_node_from_block(n);
     n->replace_by(C->top());
     return true;

src/hotspot/share/opto/lcm.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -449,7 +449,7 @@ void PhaseCFG::implicit_null_check(Block* block, Node *proj, Node *val, int allo
     old_tst->set_req(i3, NULL);
     if (in->outcnt() == 0) {
       // Remove dead input node
-      in->disconnect_inputs(NULL, C);
+      in->disconnect_inputs(C);
       block->find_remove(in);
     }
   }
@@ -1369,7 +1369,7 @@ void PhaseCFG::call_catch_cleanup(Block* block) {
 
   // Remove the now-dead cloned ops
   for(uint i3 = beg; i3 < end; i3++ ) {
-    block->get_node(beg)->disconnect_inputs(NULL, C);
+    block->get_node(beg)->disconnect_inputs(C);
     block->remove_node(beg);
   }
 
@@ -1382,7 +1382,7 @@ void PhaseCFG::call_catch_cleanup(Block* block) {
       Node *n = sb->get_node(j);
       if (n->outcnt() == 0 &&
           (!n->is_Proj() || n->as_Proj()->in(0)->outcnt() == 1) ){
-        n->disconnect_inputs(NULL, C);
+        n->disconnect_inputs(C);
         sb->remove_node(j);
         new_cnt--;
       }

src/hotspot/share/opto/macro.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2460,7 +2460,7 @@ void PhaseMacroExpand::expand_lock_node(LockNode *lock) {
   Node *slow_ctrl = _fallthroughproj->clone();
   transform_later(slow_ctrl);
   _igvn.hash_delete(_fallthroughproj);
-  _fallthroughproj->disconnect_inputs(NULL, C);
+  _fallthroughproj->disconnect_inputs(C);
   region->init_req(1, slow_ctrl);
   // region inputs are now complete
   transform_later(region);
@@ -2528,7 +2528,7 @@ void PhaseMacroExpand::expand_unlock_node(UnlockNode *unlock) {
   Node *slow_ctrl = _fallthroughproj->clone();
   transform_later(slow_ctrl);
   _igvn.hash_delete(_fallthroughproj);
-  _fallthroughproj->disconnect_inputs(NULL, C);
+  _fallthroughproj->disconnect_inputs(C);
   region->init_req(1, slow_ctrl);
   // region inputs are now complete
   transform_later(region);

src/hotspot/share/opto/node.cpp

@@ -894,33 +894,22 @@ int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 
 //-------------------------disconnect_inputs-----------------------------------
 // NULL out all inputs to eliminate incoming Def-Use edges.
-// Return the number of edges between 'n' and 'this'
-int Node::disconnect_inputs(Node *n, Compile* C) {
-  int edges_to_n = 0;
-
-  uint cnt = req();
-  for( uint i = 0; i < cnt; ++i ) {
-    if( in(i) == 0 ) continue;
-    if( in(i) == n ) ++edges_to_n;
-    set_req(i, NULL);
+void Node::disconnect_inputs(Compile* C) {
+  for (uint i = 0; i < req(); ++i) {
+    if (in(i) != nullptr) {
+      set_req(i, nullptr);
+    }
   }
+
   // Remove precedence edges if any exist
   // Note: Safepoints may have precedence edges, even during parsing
-  if( (req() != len()) && (in(req()) != NULL) ) {
-    uint max = len();
-    for( uint i = 0; i < max; ++i ) {
-      if( in(i) == 0 ) continue;
-      if( in(i) == n ) ++edges_to_n;
-      set_prec(i, NULL);
-    }
+  for (uint i = req(); i < len(); ++i) {
+    set_prec(i, nullptr);
   }
 
   // Node::destruct requires all out edges be deleted first
   // debug_only(destruct();)   // no reuse benefit expected
-  if (edges_to_n == 0) {
-    C->record_dead_node(_idx);
-  }
-  return edges_to_n;
+  C->record_dead_node(_idx);
 }
 
 //-----------------------------uncast---------------------------------------

src/hotspot/share/opto/node.hpp

@@ -446,8 +446,7 @@ class Node {
   int replace_edge(Node* old, Node* neww);
   int replace_edges_in_range(Node* old, Node* neww, int start, int end);
   // NULL out all inputs to eliminate incoming Def-Use edges.
-  // Return the number of edges between 'n' and 'this'
-  int  disconnect_inputs(Node *n, Compile *c);
+  void disconnect_inputs(Compile* C);
 
   // Quickly, return true if and only if I am Compile::current()->top().
   bool is_top() const {
@@ -517,7 +516,7 @@ class Node {
   // and cutting input edges of old node.
   void subsume_by(Node* new_node, Compile* c) {
     replace_by(new_node);
-    disconnect_inputs(NULL, c);
+    disconnect_inputs(c);
   }
   void set_req_X( uint i, Node *n, PhaseIterGVN *igvn );
   // Find the one non-null required input.  RegionNode only

src/hotspot/share/opto/postaloc.cpp

@@ -152,7 +152,7 @@ int PhaseChaitin::yank_if_dead_recurse(Node *old, Node *orig_old, Block *current
       }
     }
     // Disconnect control and remove precedence edges if any exist
-    old->disconnect_inputs(NULL, C);
+    old->disconnect_inputs(C);
   }
   return blk_adjust;
 }

src/hotspot/share/opto/reg_split.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -785,7 +785,7 @@ uint PhaseChaitin::Split(uint maxlrg, ResourceArea* split_arena) {
             if (i >= cnt) {    // Found one unique input
               assert(_lrg_map.find_id(n) == _lrg_map.find_id(u), "should be the same lrg");
               n->replace_by(u); // Then replace with unique input
-              n->disconnect_inputs(NULL, C);
+              n->disconnect_inputs(C);
               b->remove_node(insidx);
               insidx--;
               b->_ihrp_index--;

src/hotspot/share/opto/stringopts.cpp

@@ -249,13 +249,13 @@ class StringConcat : public ResourceObj {
 
       _stringopts->gvn()->transform(call);
       C->gvn_replace_by(uct, call);
-      uct->disconnect_inputs(NULL, C);
+      uct->disconnect_inputs(C);
     }
   }
 
   void cleanup() {
     // disconnect the hook node
-    _arguments->disconnect_inputs(NULL, _stringopts->C);
+    _arguments->disconnect_inputs(_stringopts->C);
   }
 };
 
@@ -373,7 +373,7 @@ void StringConcat::eliminate_initialize(InitializeNode* init) {
     C->gvn_replace_by(mem_proj, mem);
   }
   C->gvn_replace_by(init, C->top());
-  init->disconnect_inputs(NULL, C);
+  init->disconnect_inputs(C);
 }
 
 Node_List PhaseStringOpts::collect_toString_calls() {
@@ -1983,6 +1983,6 @@ void PhaseStringOpts::replace_string_concat(StringConcat* sc) {
   kit.replace_call(sc->end(), result);
 
   // Unhook any hook nodes
-  string_sizes->disconnect_inputs(NULL, C);
+  string_sizes->disconnect_inputs(C);
   sc->cleanup();
 }