diff --git a/src/hotspot/share/opto/phaseX.cpp b/src/hotspot/share/opto/phaseX.cpp
index ce5160c5984aa..63cd07da2952c 100644
--- a/src/hotspot/share/opto/phaseX.cpp
+++ b/src/hotspot/share/opto/phaseX.cpp
@@ -2566,13 +2566,16 @@ void PhaseIterGVN::add_users_of_use_to_worklist(Node* n, Node* use, Unique_Node_
   // ConvI2F->ConvF2I->ConvI2F
   // Note: there may be other 3-nodes conversion chains that would require to be added here, but these
   // are the only ones that are known to trigger missed optimizations otherwise
-  if ((n->Opcode() == Op_ConvD2L && use_op == Op_ConvL2D) ||
-      (n->Opcode() == Op_ConvF2I && use_op == Op_ConvI2F) ||
-      (n->Opcode() == Op_ConvF2L && use_op == Op_ConvL2F) ||
-      (n->Opcode() == Op_ConvI2F && use_op == Op_ConvF2I)) {
+  if (use_op == Op_ConvL2D ||
+      use_op == Op_ConvI2F ||
+      use_op == Op_ConvL2F ||
+      use_op == Op_ConvF2I) {
     for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
       Node* u = use->fast_out(i2);
-      if (u->Opcode() == n->Opcode()) {
+      if ((use_op == Op_ConvL2D && u->Opcode() == Op_ConvD2L) ||
+          (use_op == Op_ConvI2F && u->Opcode() == Op_ConvF2I) ||
+          (use_op == Op_ConvL2F && u->Opcode() == Op_ConvF2L) ||
+          (use_op == Op_ConvF2I && u->Opcode() == Op_ConvI2F)) {
         worklist.push(u);
       }
     }
diff --git a/src/hotspot/share/opto/phaseX.hpp b/src/hotspot/share/opto/phaseX.hpp
index 300c8fc27574d..b4aea5270c0a2 100644
--- a/src/hotspot/share/opto/phaseX.hpp
+++ b/src/hotspot/share/opto/phaseX.hpp
@@ -528,7 +528,21 @@ class PhaseIterGVN : public PhaseGVN {
 
   // Add users of 'n' to worklist
   static void add_users_to_worklist0(Node* n, Unique_Node_List& worklist);
+
+  // Add one or more users of 'use' to the worklist if it appears that a
+  // known optimization could be applied to those users. Certain
+  // optimizations have dependencies that extend beyond a node's direct
+  // inputs, so it is necessary to ensure the appropriate notifications
+  // are made here.
   static void add_users_of_use_to_worklist(Node* n, Node* use, Unique_Node_List& worklist);
+
+  // Add users of 'n', and any other nodes that could be directly
+  // affected by changes to 'n', to the worklist.
+  // This function may be called with a node that is about to be
+  // replaced as argument 'n'. In this case, 'n' should not be considered
+  // part of the new graph. Passing the old node (as 'n'), rather than
+  // the new node, prevents unnecessary notifications when the new node
+  // already has other users.
   void add_users_to_worklist(Node* n);
 
   // Replace old node with new one.
diff --git a/test/hotspot/jtreg/compiler/c2/TestEliminateRedundantConversionSequences.java b/test/hotspot/jtreg/compiler/c2/TestEliminateRedundantConversionSequences.java
index b452b8f67ddda..f7bcaa942305a 100644
--- a/test/hotspot/jtreg/compiler/c2/TestEliminateRedundantConversionSequences.java
+++ b/test/hotspot/jtreg/compiler/c2/TestEliminateRedundantConversionSequences.java
@@ -23,13 +23,20 @@
 
 /*
  * @test
- * @bug 8359603
+ * @bug 8359603 8369646
  * @summary Redundant ConvX2Y->ConvY2X->ConvX2Y sequences should be
  *          simplified to a single ConvX2Y operation when applicable
  *          VerifyIterativeGVN checks that this optimization was applied
  * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions
  *      -XX:CompileCommand=compileonly,compiler.c2.TestEliminateRedundantConversionSequences::test*
- *      -XX:-TieredCompilation -Xbatch -XX:VerifyIterativeGVN=1110 compiler.c2.TestEliminateRedundantConversionSequences
+ *      -XX:-TieredCompilation -Xbatch -XX:VerifyIterativeGVN=1110
+ *      -XX:+UnlockDiagnosticVMOptions -XX:+StressIGVN
+ *      compiler.c2.TestEliminateRedundantConversionSequences
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions
+ *      -XX:CompileCommand=compileonly,compiler.c2.TestEliminateRedundantConversionSequences::test*
+ *      -XX:-TieredCompilation -Xbatch -XX:VerifyIterativeGVN=1110
+ *      -XX:+UnlockDiagnosticVMOptions -XX:+StressIGVN -XX:StressSeed=115074401
+ *      compiler.c2.TestEliminateRedundantConversionSequences
  * @run main compiler.c2.TestEliminateRedundantConversionSequences
  *
  */