diff -r 56d1af561395 -r 8f972594effc src/cpu/x86/vm/c1_LIRAssembler_x86.cpp
--- a/src/cpu/x86/vm/c1_LIRAssembler_x86.cpp	Fri May 11 14:54:35 2012 -0700
+++ b/src/cpu/x86/vm/c1_LIRAssembler_x86.cpp	Mon May 14 09:36:00 2012 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2012, 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
@@ -505,19 +505,28 @@
 
   // Get addresses of first characters from both Strings
   __ load_heap_oop(rsi, Address(rax, java_lang_String::value_offset_in_bytes()));
-  __ movptr       (rcx, Address(rax, java_lang_String::offset_offset_in_bytes()));
-  __ lea          (rsi, Address(rsi, rcx, Address::times_2, arrayOopDesc::base_offset_in_bytes(T_CHAR)));
-
+  if (java_lang_String::has_offset_field()) {
+    __ movptr     (rcx, Address(rax, java_lang_String::offset_offset_in_bytes()));
+    __ movl       (rax, Address(rax, java_lang_String::count_offset_in_bytes()));
+    __ lea        (rsi, Address(rsi, rcx, Address::times_2, arrayOopDesc::base_offset_in_bytes(T_CHAR)));
+  } else {
+    __ movl       (rax, Address(rsi, arrayOopDesc::length_offset_in_bytes()));
+    __ lea        (rsi, Address(rsi, arrayOopDesc::base_offset_in_bytes(T_CHAR)));
+  }
 
   // rbx, may be NULL
   add_debug_info_for_null_check_here(info);
   __ load_heap_oop(rdi, Address(rbx, java_lang_String::value_offset_in_bytes()));
-  __ movptr       (rcx, Address(rbx, java_lang_String::offset_offset_in_bytes()));
-  __ lea          (rdi, Address(rdi, rcx, Address::times_2, arrayOopDesc::base_offset_in_bytes(T_CHAR)));
+  if (java_lang_String::has_offset_field()) {
+    __ movptr     (rcx, Address(rbx, java_lang_String::offset_offset_in_bytes()));
+    __ movl       (rbx, Address(rbx, java_lang_String::count_offset_in_bytes()));
+    __ lea        (rdi, Address(rdi, rcx, Address::times_2, arrayOopDesc::base_offset_in_bytes(T_CHAR)));
+  } else {
+    __ movl       (rbx, Address(rdi, arrayOopDesc::length_offset_in_bytes()));
+    __ lea        (rdi, Address(rdi, arrayOopDesc::base_offset_in_bytes(T_CHAR)));
+  }
 
   // compute minimum length (in rax) and difference of lengths (on top of stack)
-  __ movl  (rbx, Address(rbx, java_lang_String::count_offset_in_bytes()));
-  __ movl  (rax, Address(rax, java_lang_String::count_offset_in_bytes()));
   __ mov   (rcx, rbx);
   __ subptr(rbx, rax); // subtract lengths
   __ push  (rbx);      // result