[vmkit-commits] [PATCH] In OpenJDK, use the 'classes' field of ClassLoader to track VMClassLoader.

[Will Dietz]

Inlined below.

Traces the internal classloader by stashing a VMClassLoader into the
'classes' field.

FWIW the *only* time anyone 'writes' to the classes field is
initializing it to empty in the constructor.

~Will

>From 1b728ad7ab762680abe320eaf9f66e1e5c981560 Mon Sep 17 00:00:00 2001
From: Will Dietz <w at wdtz.org>
Date: Wed, 2 Nov 2011 22:48:26 -0500
Subject: [PATCH 13/17] In OpenJDK, use the 'classes' field of ClassLoader to
 track VMClassLoader.

Also, don't just check the 'vmdata' field for non-null, since in OJ it will be
initialized to an empty vector.  Instead, consider the field uninitialized if
it's either null or of the wrong type.
---
 lib/J3/ClassLib/OpenJDK/JavaUpcalls.cpp |    7 +++----
 lib/J3/VMCore/JnjvmClassLoader.cpp      |    7 +++++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/J3/ClassLib/OpenJDK/JavaUpcalls.cpp
b/lib/J3/ClassLib/OpenJDK/JavaUpcalls.cpp
index 43ff227..22db276 100644
--- a/lib/J3/ClassLib/OpenJDK/JavaUpcalls.cpp
+++ b/lib/J3/ClassLib/OpenJDK/JavaUpcalls.cpp
@@ -552,10 +552,9 @@ void
Classpath::initialiseClasspath(JnjvmClassLoader* loader) {
     UPCALL_FIELD(loader, "java/nio/Buffer", "address",
"Lgnu/classpath/Pointer;",
                  ACC_VIRTUAL);

-  // TODO: Resolve how to tie a ClassLoader to its internal representation
-  //vmdataClassLoader =
-  //  UPCALL_FIELD(loader, "java/lang/ClassLoader", "vmdata",
"Ljava/lang/Object;",
-  //               ACC_VIRTUAL);
+  vmdataClassLoader =
+    UPCALL_FIELD(loader, "java/lang/ClassLoader", "classes",
"Ljava/util/Vector;",
+                 ACC_VIRTUAL);

   newStackTraceElement =
     UPCALL_CLASS(loader, "java/lang/StackTraceElement");
diff --git a/lib/J3/VMCore/JnjvmClassLoader.cpp
b/lib/J3/VMCore/JnjvmClassLoader.cpp
index 5444941..fd1eabb 100644
--- a/lib/J3/VMCore/JnjvmClassLoader.cpp
+++ b/lib/J3/VMCore/JnjvmClassLoader.cpp
@@ -808,11 +808,14 @@
JnjvmClassLoader::getJnjvmLoaderFromJavaObject(JavaObject* loader,
Jnjvm* vm) {
   vmdata =
     (VMClassLoader*)(upcalls->vmdataClassLoader->getInstanceObjectField(loader));

-  if (vmdata == NULL) {
+  // If the vmdata field isn't set yet, or it's set to something other than
+  // a VMClassLoader (which happens in the OpenJDK port), then initialize
+  // the field now.
+  if (vmdata == NULL || !VMClassLoader::isVMClassLoader(vmdata)) {
     JavaObject::acquire(loader);
     vmdata =
       (VMClassLoader*)(upcalls->vmdataClassLoader->getInstanceObjectField(loader));
-    if (!vmdata) {
+    if (!vmdata || !VMClassLoader::isVMClassLoader(vmdata)) {
       vmdata = VMClassLoader::allocate();
       mvm::BumpPtrAllocator* A = new mvm::BumpPtrAllocator();
       JCL = new(*A, "Class loader") JnjvmClassLoader(*A, *vm->bootstrapLoader,
-- 
1.7.5.1