diff -r b363f6ef4068 -r 7fc02fbe5c7a hotspot/src/share/vm/ci/ciInstanceKlass.cpp
--- a/hotspot/src/share/vm/ci/ciInstanceKlass.cpp	Tue Jan 05 13:05:58 2010 +0100
+++ b/hotspot/src/share/vm/ci/ciInstanceKlass.cpp	Tue Jan 05 15:21:25 2010 +0100
@@ -232,8 +232,48 @@
 // ------------------------------------------------------------------
 // ciInstanceKlass::uses_default_loader
 bool ciInstanceKlass::uses_default_loader() {
-  VM_ENTRY_MARK;
-  return loader() == NULL;
+  // Note:  We do not need to resolve the handle or enter the VM
+  // in order to test null-ness.
+  return _loader == NULL;
+}
+
+// ------------------------------------------------------------------
+// ciInstanceKlass::is_in_package
+//
+// Is this klass in the given package?
+bool ciInstanceKlass::is_in_package(const char* packagename, int len) {
+  // To avoid class loader mischief, this test always rejects application classes.
+  if (!uses_default_loader())
+    return false;
+  GUARDED_VM_ENTRY(
+    return is_in_package_impl(packagename, len);
+  )
+}
+
+bool ciInstanceKlass::is_in_package_impl(const char* packagename, int len) {
+  ASSERT_IN_VM;
+
+  // If packagename contains trailing '/' exclude it from the
+  // prefix-test since we test for it explicitly.
+  if (packagename[len - 1] == '/')
+    len--;
+
+  if (!name()->starts_with(packagename, len))
+    return false;
+
+  // Test if the class name is something like "java/lang".
+  if ((len + 1) > name()->utf8_length())
+    return false;
+
+  // Test for trailing '/'
+  if ((char) name()->byte_at(len) != '/')
+    return false;
+
+  // Make sure it's not actually in a subpackage:
+  if (name()->index_of_at(len+1, "/", 1) >= 0)
+    return false;
+
+  return true;
 }
 
 // ------------------------------------------------------------------