--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.asm/src/org/graalvm/compiler/asm/Assembler.java	Tue Apr 23 14:09:54 2019 -0400
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.asm/src/org/graalvm/compiler/asm/Assembler.java	Tue Apr 23 22:55:09 2019 +0200
@@ -54,6 +54,11 @@
     private List<LabelHint> jumpDisplacementHints;
 
     /**
+     * Labels with instructions to be patched when it is {@linkplain Label#bind bound}.
+     */
+    Label labelsWithPatches;
+
+    /**
      * Backing code buffer.
      */
     private final Buffer codeBuffer;
@@ -151,13 +156,26 @@
      * @return the data in this buffer or a trimmed copy if {@code trimmedCopy} is {@code true}
      */
     public byte[] close(boolean trimmedCopy) {
+        checkAndClearLabelsWithPatches();
         return codeBuffer.close(trimmedCopy);
     }
 
+    private void checkAndClearLabelsWithPatches() throws InternalError {
+        Label label = labelsWithPatches;
+        while (label != null) {
+            if (label.patchPositions != null) {
+                throw new InternalError("Label used by instructions at following offsets has not been bound: " + label.patchPositions);
+            }
+            Label next = label.nextWithPatches;
+            label.nextWithPatches = null;
+            label = next;
+        }
+        labelsWithPatches = null;
+    }
+
     public void bind(Label l) {
         assert !l.isBound() : "can bind label only once";
-        l.bind(position());
-        l.patchInstructions(this);
+        l.bind(position(), this);
     }
 
     public abstract void align(int modulus);