diff -r 2251ba078bec -r eb7ce841ccec src/share/vm/opto/compile.cpp
--- a/src/share/vm/opto/compile.cpp	Sat Oct 24 16:18:50 2020 +0800
+++ b/src/share/vm/opto/compile.cpp	Sat Oct 24 16:43:47 2020 +0800
@@ -1170,6 +1170,9 @@
   _expensive_nodes = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
   _range_check_casts = new(comp_arena()) GrowableArray<Node*>(comp_arena(), 8,  0, NULL);
   register_library_intrinsics();
+#ifdef ASSERT
+  _type_verify_symmetry = true;
+#endif
 }
 
 //---------------------------init_start----------------------------------------
@@ -2083,6 +2086,23 @@
 }
 
 
+// Remove edges from "root" to each SafePoint at a backward branch.
+// They were inserted during parsing (see add_safepoint()) to make
+// infinite loops without calls or exceptions visible to root, i.e.,
+// useful.
+void Compile::remove_root_to_sfpts_edges() {
+  Node *r = root();
+  if (r != NULL) {
+    for (uint i = r->req(); i < r->len(); ++i) {
+      Node *n = r->in(i);
+      if (n != NULL && n->is_SafePoint()) {
+        r->rm_prec(i);
+        --i;
+      }
+    }
+  }
+}
+
 //------------------------------Optimize---------------------------------------
 // Given a graph, optimize it.
 void Compile::Optimize() {
@@ -2138,6 +2158,10 @@
     if (failing())  return;
   }
 
+  // Now that all inlining is over, cut edge from root to loop
+  // safepoints
+  remove_root_to_sfpts_edges();
+
   // Remove the speculative part of types and clean up the graph from
   // the extra CastPP nodes whose only purpose is to carry them. Do
   // that early so that optimizations are not disrupted by the extra
@@ -3020,8 +3044,10 @@
             break;
           }
         }
-        assert(proj != NULL, "must be found");
-        p->subsume_by(proj, this);
+        assert(proj != NULL || p->_con == TypeFunc::I_O, "io may be dropped at an infinite loop");
+        if (proj != NULL) {
+          p->subsume_by(proj, this);
+        }
       }
     }
     break;