From 17503baaccb86d9f877d44be5d3613593ae8cf57 Mon Sep 17 00:00:00 2001
From: jingduanyang <jingduanyang.0@bytedance.com>
Date: Tue, 7 Apr 2026 10:57:53 +0800
Subject: [PATCH] Backport: 8261449: Micro-optimize JVM_LatestUserDefinedLoader

---
 src/hotspot/share/prims/jvm.cpp      | 13 ++++---------
 src/hotspot/share/runtime/vframe.cpp |  9 ---------
 src/hotspot/share/runtime/vframe.hpp |  5 -----
 3 files changed, 4 insertions(+), 23 deletions(-)

diff --git a/src/hotspot/share/prims/jvm.cpp b/src/hotspot/share/prims/jvm.cpp
index a6977473edf..f6389e9d897 100644
--- a/src/hotspot/share/prims/jvm.cpp
+++ b/src/hotspot/share/prims/jvm.cpp
@@ -3310,24 +3310,19 @@ JVM_END
 
 JVM_ENTRY(jobject, JVM_LatestUserDefinedLoader(JNIEnv *env))
   for (vframeStream vfst(thread); !vfst.at_end(); vfst.next()) {
-#if HOTSPOT_TARGET_CLASSLIB == 8
-    // UseNewReflection
-    vfst.skip_reflection_related_frames(); // Only needed for 1.4 reflection
-    oop loader = vfst.method()->method_holder()->class_loader();
-    if (loader != NULL && !SystemDictionary::is_ext_class_loader(Handle(THREAD, loader))) {
-      return JNIHandles::make_local(THREAD, loader);
-    }
-#else
     InstanceKlass* ik = vfst.method()->method_holder();
     oop loader = ik->class_loader();
+#if HOTSPOT_TARGET_CLASSLIB == 8
+    if (loader != nullptr && !SystemDictionary::is_ext_class_loader(Handle(THREAD, loader))) {
+#else
     if (loader != NULL && !SystemDictionary::is_platform_class_loader(loader)) {
+#endif // HOTSPOT_TARGET_CLASSLIB == 8
       // Skip reflection related frames
       if (!ik->is_subclass_of(vmClasses::reflect_MethodAccessorImpl_klass()) &&
           !ik->is_subclass_of(vmClasses::reflect_ConstructorAccessorImpl_klass())) {
         return JNIHandles::make_local(THREAD, loader);
       }
     }
-#endif // HOTSPOT_TARGET_CLASSLIB == 8
   }
   return NULL;
 JVM_END
diff --git a/src/hotspot/share/runtime/vframe.cpp b/src/hotspot/share/runtime/vframe.cpp
index 9087e6a95b8..d51c842458e 100644
--- a/src/hotspot/share/runtime/vframe.cpp
+++ b/src/hotspot/share/runtime/vframe.cpp
@@ -604,15 +604,6 @@ javaVFrame* vframeStreamCommon::asJavaVFrame() {
   return result;
 }
 
-#if HOTSPOT_TARGET_CLASSLIB == 8
-void vframeStreamCommon::skip_reflection_related_frames() {
-  while (!at_end() &&
-          (method()->method_holder()->is_subclass_of(vmClasses::reflect_MethodAccessorImpl_klass()) ||
-           method()->method_holder()->is_subclass_of(vmClasses::reflect_ConstructorAccessorImpl_klass()))) {
-    next();
-  }
-}
-#endif
 
 #ifndef PRODUCT
 void vframe::print() {
diff --git a/src/hotspot/share/runtime/vframe.hpp b/src/hotspot/share/runtime/vframe.hpp
index 58c76a43309..9ae435a926d 100644
--- a/src/hotspot/share/runtime/vframe.hpp
+++ b/src/hotspot/share/runtime/vframe.hpp
@@ -335,11 +335,6 @@ class vframeStreamCommon : StackObj {
   // special security frames and prefixed native methods
   void security_get_caller_frame(int depth);
 
-#if HOTSPOT_TARGET_CLASSLIB == 8  
-  // Helper routine for JVM_LatestUserDefinedLoader -- needed for 1.4
-  // reflection implementation
-  void skip_reflection_related_frames();
-#endif
 };
 
 class vframeStream : public vframeStreamCommon {