--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/LogicNode.java	2019-03-12 08:09:46.971647053 +0100
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/LogicNode.java	2019-03-12 08:09:46.603644667 +0100
@@ -91,6 +91,18 @@
      * @param other the other condition.
      */
     public TriState implies(boolean thisNegated, LogicNode other) {
+        if (this == other) {
+            return TriState.get(!thisNegated);
+        }
+        if (other instanceof LogicNegationNode) {
+            return flip(this.implies(thisNegated, ((LogicNegationNode) other).getValue()));
+        }
         return TriState.UNKNOWN;
     }
+
+    private static TriState flip(TriState triState) {
+        return triState.isUnknown()
+                        ? triState
+                        : TriState.get(!triState.toBoolean());
+    }
 }