8174164: SafePointNode::_replaced_nodes breaks with irreducible loops

Reviewed-by: kvn

src/share/vm/opto/callnode.hpp

@@ -449,8 +449,8 @@ public:
   void delete_replaced_nodes() {
     _replaced_nodes.reset();
   }
-  void apply_replaced_nodes() {
-    _replaced_nodes.apply(this);
+  void apply_replaced_nodes(uint idx) {
+    _replaced_nodes.apply(this, idx);
   }
   void merge_replaced_nodes_with(SafePointNode* sfpt) {
     _replaced_nodes.merge_with(sfpt->_replaced_nodes);

src/share/vm/opto/parse1.cpp

@@ -1048,7 +1048,7 @@ void Parse::do_exits() {
         kit.make_dtrace_method_exit(method());
       }
       if (_replaced_nodes_for_exceptions) {
-        kit.map()->apply_replaced_nodes();
+        kit.map()->apply_replaced_nodes(_new_idx);
       }
       // Done with exception-path processing.
       ex_map = kit.make_exception_state(ex_oop);
@@ -1069,7 +1069,7 @@ void Parse::do_exits() {
       _exits.add_exception_state(ex_map);
     }
   }
-  _exits.map()->apply_replaced_nodes();
+  _exits.map()->apply_replaced_nodes(_new_idx);
 }
 
 //-----------------------------create_entry_map-------------------------------

src/share/vm/opto/replacednodes.cpp

@@ -91,13 +91,17 @@ void ReplacedNodes::reset() {
 }
 
 // Perfom node replacement (used when returning to caller)
-void ReplacedNodes::apply(Node* n) {
+void ReplacedNodes::apply(Node* n, uint idx) {
   if (is_empty()) {
     return;
   }
   for (int i = 0; i < _replaced_nodes->length(); i++) {
     ReplacedNode replaced = _replaced_nodes->at(i);
-    n->replace_edge(replaced.initial(), replaced.improved());
+    // Only apply if improved node was created in a callee to avoid
+    // issues with irreducible loops in the caller
+    if (replaced.improved()->_idx >= idx) {
+      n->replace_edge(replaced.initial(), replaced.improved());
+    }
   }
 }
 

src/share/vm/opto/replacednodes.hpp

@@ -71,7 +71,7 @@ class ReplacedNodes VALUE_OBJ_CLASS_SPEC {
   void record(Node* initial, Node* improved);
   void transfer_from(const ReplacedNodes& other, uint idx);
   void reset();
-  void apply(Node* n);
+  void apply(Node* n, uint idx);
   void merge_with(const ReplacedNodes& other);
   bool is_empty() const;
   void dump(outputStream *st) const;