diff -r 0152ad7b38b8 -r 6df94ce3ab2f src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.amd64/src/org/graalvm/compiler/replacements/amd64/AMD64StringSubstitutions.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.amd64/src/org/graalvm/compiler/replacements/amd64/AMD64StringSubstitutions.java	Tue Sep 24 08:54:08 2019 -0700
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.amd64/src/org/graalvm/compiler/replacements/amd64/AMD64StringSubstitutions.java	Tue Sep 24 12:47:15 2019 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -85,8 +85,6 @@
 
         if (targetCount == 1) {
             return AMD64ArrayIndexOf.indexOf1Char(source, sourceCount, totalOffset, target[targetOffset]);
-        } else if (targetCount == 2) {
-            return AMD64ArrayIndexOf.indexOfTwoConsecutiveChars(source, sourceCount, totalOffset, target[targetOffset], target[targetOffset + 1]);
         } else {
             int haystackLength = sourceCount - (targetCount - 2);
             while (totalOffset < haystackLength) {
@@ -95,10 +93,14 @@
                     return -1;
                 }
                 totalOffset = indexOfResult;
-                Pointer cmpSourcePointer = Word.objectToTrackedPointer(source).add(charArrayBaseOffset(INJECTED)).add(totalOffset * charArrayIndexScale(INJECTED));
-                Pointer targetPointer = Word.objectToTrackedPointer(target).add(charArrayBaseOffset(INJECTED)).add(targetOffset * charArrayIndexScale(INJECTED));
-                if (ArrayRegionEqualsNode.regionEquals(cmpSourcePointer, targetPointer, targetCount, JavaKind.Char)) {
+                if (targetCount == 2) {
                     return totalOffset;
+                } else {
+                    Pointer cmpSourcePointer = Word.objectToTrackedPointer(source).add(charArrayBaseOffset(INJECTED)).add(totalOffset * charArrayIndexScale(INJECTED));
+                    Pointer targetPointer = Word.objectToTrackedPointer(target).add(charArrayBaseOffset(INJECTED)).add(targetOffset * charArrayIndexScale(INJECTED));
+                    if (ArrayRegionEqualsNode.regionEquals(cmpSourcePointer, targetPointer, targetCount, JavaKind.Char)) {
+                        return totalOffset;
+                    }
                 }
                 totalOffset++;
             }