src/hotspot/share/opto/compile.cpp
changeset 53220 c14b7b6a9b2f
parent 53063 b04860fd2e2c
child 53429 1b292ae4eb50
--- a/src/hotspot/share/opto/compile.cpp	Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/compile.cpp	Fri Dec 07 17:56:51 2018 +0100
@@ -2184,6 +2184,23 @@
   return true;
 }
 
+// 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() {
@@ -2244,6 +2261,10 @@
     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
@@ -3248,8 +3269,10 @@
             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;