8025841: JVMTI: "vtable stub" dynamic code notification is misplaced

Summary: Generate correct "vtable stub" dynamic code notifications
Reviewed-by: sspitsyn, kvn, coleenp
Contributed-by: oleg.mazurov@oracle.com

src/share/vm/code/vtableStubs.cpp

@@ -55,6 +55,9 @@ void* VtableStub::operator new(size_t size, int code_size) throw() {
   const int chunk_factor = 32;
   if (_chunk == NULL || _chunk + real_size > _chunk_end) {
     const int bytes = chunk_factor * real_size + pd_code_alignment();
+
+   // There is a dependency on the name of the blob in src/share/vm/prims/jvmtiCodeBlobEvents.cpp
+   // If changing the name, update the other file accordingly.
     BufferBlob* blob = BufferBlob::create("vtable chunks", bytes);
     if (blob == NULL) {
       return NULL;
@@ -62,12 +65,6 @@ void* VtableStub::operator new(size_t size, int code_size) throw() {
     _chunk = blob->content_begin();
     _chunk_end = _chunk + bytes;
     Forte::register_stub("vtable stub", _chunk, _chunk_end);
-    // Notify JVMTI about this stub. The event will be recorded by the enclosing
-    // JvmtiDynamicCodeEventCollector and posted when this thread has released
-    // all locks.
-    if (JvmtiExport::should_post_dynamic_code_generated()) {
-      JvmtiExport::post_dynamic_code_generated_while_holding_locks("vtable stub", _chunk, _chunk_end);
-    }
     align_chunk();
   }
   assert(_chunk + real_size <= _chunk_end, "bad allocation");
@@ -130,6 +127,13 @@ address VtableStubs::find_stub(bool is_vtable_stub, int vtable_index) {
                     is_vtable_stub? "vtbl": "itbl", vtable_index, VtableStub::receiver_location());
       Disassembler::decode(s->code_begin(), s->code_end());
     }
+    // Notify JVMTI about this stub. The event will be recorded by the enclosing
+    // JvmtiDynamicCodeEventCollector and posted when this thread has released
+    // all locks.
+    if (JvmtiExport::should_post_dynamic_code_generated()) {
+      JvmtiExport::post_dynamic_code_generated_while_holding_locks(is_vtable_stub? "vtable stub": "itable stub",
+                                                                   s->code_begin(), s->code_end());
+    }
   }
   return s->entry_point();
 }
@@ -195,6 +199,14 @@ void vtableStubs_init() {
   VtableStubs::initialize();
 }
 
+void VtableStubs::vtable_stub_do(void f(VtableStub*)) {
+    for (int i = 0; i < N; i++) {
+        for (VtableStub* s = _table[i]; s != NULL; s = s->next()) {
+            f(s);
+        }
+    }
+}
+
 
 //-----------------------------------------------------------------------------------------------------
 // Non-product code

src/share/vm/code/vtableStubs.hpp

@@ -131,6 +131,7 @@ class VtableStubs : AllStatic {
   static VtableStub* stub_containing(address pc);                    // stub containing pc or NULL
   static int         number_of_vtable_stubs() { return _number_of_vtable_stubs; }
   static void        initialize();
+  static void        vtable_stub_do(void f(VtableStub*));            // iterates over all vtable stubs
 };
 
 #endif // SHARE_VM_CODE_VTABLESTUBS_HPP

src/share/vm/prims/jvmtiCodeBlobEvents.cpp

@@ -26,6 +26,7 @@
 #include "code/codeBlob.hpp"
 #include "code/codeCache.hpp"
 #include "code/scopeDesc.hpp"
+#include "code/vtableStubs.hpp"
 #include "memory/resourceArea.hpp"
 #include "oops/oop.inline.hpp"
 #include "prims/jvmtiCodeBlobEvents.hpp"
@@ -63,6 +64,7 @@ class CodeBlobCollector : StackObj {
   // used during a collection
   static GrowableArray<JvmtiCodeBlobDesc*>* _global_code_blobs;
   static void do_blob(CodeBlob* cb);
+  static void do_vtable_stub(VtableStub* vs);
  public:
   CodeBlobCollector() {
     _code_blobs = NULL;
@@ -119,6 +121,10 @@ void CodeBlobCollector::do_blob(CodeBlob* cb) {
   if (cb->is_nmethod()) {
     return;
   }
+  // exclude VtableStubs, which are processed separately
+  if (cb->is_buffer_blob() && strcmp(cb->name(), "vtable chunks") == 0) {
+    return;
+  }
 
   // check if this starting address has been seen already - the
   // assumption is that stubs are inserted into the list before the
@@ -136,6 +142,13 @@ void CodeBlobCollector::do_blob(CodeBlob* cb) {
   _global_code_blobs->append(scb);
 }
 
+// called for each VtableStub in VtableStubs
+
+void CodeBlobCollector::do_vtable_stub(VtableStub* vs) {
+    JvmtiCodeBlobDesc* scb = new JvmtiCodeBlobDesc(vs->is_vtable_stub() ? "vtable stub" : "itable stub",
+                                                   vs->code_begin(), vs->code_end());
+    _global_code_blobs->append(scb);
+}
 
 // collects a list of CodeBlobs in the CodeCache.
 //
@@ -166,6 +179,10 @@ void CodeBlobCollector::collect() {
     _global_code_blobs->append(new JvmtiCodeBlobDesc(desc->name(), desc->begin(), desc->end()));
   }
 
+  // Vtable stubs are not described with StubCodeDesc,
+  // process them separately
+  VtableStubs::vtable_stub_do(do_vtable_stub);
+
   // next iterate over all the non-nmethod code blobs and add them to
   // the list - as noted above this will filter out duplicates and
   // enclosing blobs.