7004582: Add GetThisObject() function to JVMTI 1.2

Summary: Add 'GetThisObject' function
Reviewed-by: never, coleenp

src/share/vm/code/nmethod.cpp

@@ -619,8 +619,8 @@ nmethod::nmethod(
   OopMapSet* oop_maps )
   : CodeBlob("native nmethod", code_buffer, sizeof(nmethod),
              nmethod_size, offsets->value(CodeOffsets::Frame_Complete), frame_size, oop_maps),
-  _compiled_synchronized_native_basic_lock_owner_sp_offset(basic_lock_owner_sp_offset),
-  _compiled_synchronized_native_basic_lock_sp_offset(basic_lock_sp_offset)
+  _native_receiver_sp_offset(basic_lock_owner_sp_offset),
+  _native_basic_lock_sp_offset(basic_lock_sp_offset)
 {
   {
     debug_only(No_Safepoint_Verifier nsv;)
@@ -696,8 +696,8 @@ nmethod::nmethod(
   int frame_size)
   : CodeBlob("dtrace nmethod", code_buffer, sizeof(nmethod),
              nmethod_size, offsets->value(CodeOffsets::Frame_Complete), frame_size, NULL),
-  _compiled_synchronized_native_basic_lock_owner_sp_offset(in_ByteSize(-1)),
-  _compiled_synchronized_native_basic_lock_sp_offset(in_ByteSize(-1))
+  _native_receiver_sp_offset(in_ByteSize(-1)),
+  _native_basic_lock_sp_offset(in_ByteSize(-1))
 {
   {
     debug_only(No_Safepoint_Verifier nsv;)
@@ -790,8 +790,8 @@ nmethod::nmethod(
   )
   : CodeBlob("nmethod", code_buffer, sizeof(nmethod),
              nmethod_size, offsets->value(CodeOffsets::Frame_Complete), frame_size, oop_maps),
-  _compiled_synchronized_native_basic_lock_owner_sp_offset(in_ByteSize(-1)),
-  _compiled_synchronized_native_basic_lock_sp_offset(in_ByteSize(-1))
+  _native_receiver_sp_offset(in_ByteSize(-1)),
+  _native_basic_lock_sp_offset(in_ByteSize(-1))
 {
   assert(debug_info->oop_recorder() == code_buffer->oop_recorder(), "shared OR");
   {

src/share/vm/code/nmethod.hpp

@@ -210,7 +210,7 @@ class nmethod : public CodeBlob {
   ExceptionCache *_exception_cache;
   PcDescCache     _pc_desc_cache;
 
-  // These are only used for compiled synchronized native methods to
+  // These are used for compiled synchronized native methods to
   // locate the owner and stack slot for the BasicLock so that we can
   // properly revoke the bias of the owner if necessary. They are
   // needed because there is no debug information for compiled native
@@ -220,8 +220,10 @@ class nmethod : public CodeBlob {
   // sharing between platforms. Note that currently biased locking
   // will never cause Class instances to be biased but this code
   // handles the static synchronized case as well.
-  ByteSize _compiled_synchronized_native_basic_lock_owner_sp_offset;
-  ByteSize _compiled_synchronized_native_basic_lock_sp_offset;
+  // JVMTI's GetLocalInstance() also uses these offsets to find the receiver
+  // for non-static native wrapper frames.
+  ByteSize _native_receiver_sp_offset;
+  ByteSize _native_basic_lock_sp_offset;
 
   friend class nmethodLocker;
 
@@ -676,11 +678,11 @@ public:
   bool is_patchable_at(address instr_address);
 
   // UseBiasedLocking support
-  ByteSize compiled_synchronized_native_basic_lock_owner_sp_offset() {
-    return _compiled_synchronized_native_basic_lock_owner_sp_offset;
+  ByteSize native_receiver_sp_offset() {
+    return _native_receiver_sp_offset;
   }
-  ByteSize compiled_synchronized_native_basic_lock_sp_offset() {
-    return _compiled_synchronized_native_basic_lock_sp_offset;
+  ByteSize native_basic_lock_sp_offset() {
+    return _native_basic_lock_sp_offset;
   }
 
   // support for code generation

src/share/vm/prims/jvmti.xml

@@ -5649,6 +5649,45 @@ class C2 extends C1 implements I2 {
       </errors>
     </function>
 
+    <function id="GetLocalInstance" num="155" since="1.2">
+      <synopsis>Get Local Instance</synopsis>
+      <description>
+        This function can be used to retrieve the value of the local object
+        variable at slot 0 (the "<code>this</code>" object) from non-static
+        frames.  This function can retrieve the "<code>this</code>" object from
+        native method frames, whereas <code>GetLocalObject()</code> would 
+        return <code>JVMTI_ERROR_OPAQUE_FRAME</code> in those cases.
+      </description>
+      <origin>new</origin>
+      <capabilities>
+	<required id="can_access_local_variables"></required>
+      </capabilities>
+      <parameters>
+ 	<param id="thread">
+	  <jthread null="current" frame="frame"/>
+	  <description>
+	    The thread of the frame containing the variable's value.
+	  </description>
+	</param>
+	<param id="depth">
+	  <jframeID thread="thread"/>
+	  <description>
+	    The depth of the frame containing the variable's value.
+	  </description>
+	</param>
+	<param id="value_ptr">
+	  <outptr><jobject/></outptr>
+	    <description>
+	      On return, points to the variable's value. 
+	    </description>
+	</param>
+      </parameters>
+      <errors>
+	<error id="JVMTI_ERROR_INVALID_SLOT">
+	  If the specified frame is a static method frame.
+	</error>
+      </errors>
+    </function>
     <function id="GetLocalInt" num="22">
       <synopsis>Get Local Variable - Int</synopsis>
       <description>

src/share/vm/prims/jvmtiEnv.cpp

@@ -1796,6 +1796,29 @@ JvmtiEnv::GetLocalObject(JavaThread* java_thread, jint depth, jint slot, jobject
   }
 } /* end GetLocalObject */
 
+// Threads_lock NOT held, java_thread not protected by lock
+// java_thread - pre-checked
+// java_thread - unchecked
+// depth - pre-checked as non-negative
+// value - pre-checked for NULL
+jvmtiError
+JvmtiEnv::GetLocalInstance(JavaThread* java_thread, jint depth, jobject* value){
+  JavaThread* current_thread = JavaThread::current();
+  // rm object is created to clean up the javaVFrame created in
+  // doit_prologue(), but after doit() is finished with it.
+  ResourceMark rm(current_thread);
+
+  VM_GetReceiver op(java_thread, current_thread, depth);
+  VMThread::execute(&op);
+  jvmtiError err = op.result();
+  if (err != JVMTI_ERROR_NONE) {
+    return err;
+  } else {
+    *value = op.value().l;
+    return JVMTI_ERROR_NONE;
+  }
+} /* end GetLocalInstance */
+
 
 // Threads_lock NOT held, java_thread not protected by lock
 // java_thread - pre-checked

src/share/vm/prims/jvmtiImpl.cpp

@@ -586,7 +586,6 @@ VM_GetOrSetLocal::VM_GetOrSetLocal(JavaThread* thread, JavaThread* calling_threa
 {
 }
 
-
 vframe *VM_GetOrSetLocal::get_vframe() {
   if (!_thread->has_last_Java_frame()) {
     return NULL;
@@ -609,7 +608,7 @@ javaVFrame *VM_GetOrSetLocal::get_java_vframe() {
   }
   javaVFrame *jvf = (javaVFrame*)vf;
 
-  if (!vf->is_java_frame() || jvf->method()->is_native()) {
+  if (!vf->is_java_frame()) {
     _result = JVMTI_ERROR_OPAQUE_FRAME;
     return NULL;
   }
@@ -740,6 +739,15 @@ bool VM_GetOrSetLocal::doit_prologue() {
   _jvf = get_java_vframe();
   NULL_CHECK(_jvf, false);
 
+  if (_jvf->method()->is_native()) {
+    if (getting_receiver() && !_jvf->method()->is_static()) {
+      return true;
+    } else {
+      _result = JVMTI_ERROR_OPAQUE_FRAME;
+      return false;
+    }
+  }
+
   if (!check_slot_type(_jvf)) {
     return false;
   }
@@ -793,6 +801,11 @@ void VM_GetOrSetLocal::doit() {
       default: ShouldNotReachHere();
     }
     _jvf->set_locals(locals);
+  } else {
+    if (_jvf->method()->is_native() && _jvf->is_compiled_frame()) {
+      assert(getting_receiver(), "Can only get here when getting receiver");
+      oop receiver = _jvf->fr().get_native_receiver();
+      _value.l = JNIHandles::make_local(_calling_thread, receiver);
     } else {
       StackValueCollection *locals = _jvf->locals();
 
@@ -817,6 +830,7 @@ void VM_GetOrSetLocal::doit() {
         default: ShouldNotReachHere();
       }
     }
+  }
 }
 
 
@@ -825,6 +839,10 @@ bool VM_GetOrSetLocal::allow_nested_vm_operations() const {
 }
 
 
+VM_GetReceiver::VM_GetReceiver(
+    JavaThread* thread, JavaThread* caller_thread, jint depth)
+    : VM_GetOrSetLocal(thread, caller_thread, depth, 0) {}
+
 /////////////////////////////////////////////////////////////////////////////////////////
 
 //

src/share/vm/prims/jvmtiImpl.hpp

@@ -355,7 +355,7 @@ bool JvmtiCurrentBreakpoints::is_breakpoint(address bcp) {
 // to the thread simultaneously.
 //
 class VM_GetOrSetLocal : public VM_Operation {
-private:
+ protected:
   JavaThread* _thread;
   JavaThread* _calling_thread;
   jint        _depth;
@@ -365,6 +365,10 @@ private:
   javaVFrame* _jvf;
   bool        _set;
 
+  // It is possible to get the receiver out of a non-static native wrapper
+  // frame.  Use VM_GetReceiver to do this.
+  virtual bool getting_receiver() const { return false; }
+
   jvmtiError  _result;
 
   vframe* get_vframe();
@@ -395,6 +399,15 @@ public:
   static bool is_assignable(const char* ty_sign, Klass* klass, Thread* thread);
 };
 
+class VM_GetReceiver : public VM_GetOrSetLocal {
+ protected:
+  virtual bool getting_receiver() const { return true; }
+
+ public:
+  VM_GetReceiver(JavaThread* thread, JavaThread* calling_thread, jint depth);
+  const char* name() const                       { return "get receiver"; }
+};
+
 
 ///////////////////////////////////////////////////////////////
 //

src/share/vm/runtime/frame.cpp

@@ -1071,28 +1071,20 @@ oop* frame::oopmapreg_to_location(VMReg reg, const RegisterMap* reg_map) const {
   }
 }
 
-BasicLock* frame::compiled_synchronized_native_monitor(nmethod* nm) {
-  if (nm == NULL) {
-    assert(_cb != NULL && _cb->is_nmethod() &&
-           nm->method()->is_native() &&
-           nm->method()->is_synchronized(),
-           "should not call this otherwise");
-    nm = (nmethod*) _cb;
-  }
-  int byte_offset = in_bytes(nm->compiled_synchronized_native_basic_lock_sp_offset());
+BasicLock* frame::get_native_monitor() {
+  nmethod* nm = (nmethod*)_cb;
+  assert(_cb != NULL && _cb->is_nmethod() && nm->method()->is_native(),
+         "Should not call this unless it's a native nmethod");
+  int byte_offset = in_bytes(nm->native_basic_lock_sp_offset());
   assert(byte_offset >= 0, "should not see invalid offset");
   return (BasicLock*) &sp()[byte_offset / wordSize];
 }
 
-oop frame::compiled_synchronized_native_monitor_owner(nmethod* nm) {
-  if (nm == NULL) {
-    assert(_cb != NULL && _cb->is_nmethod() &&
-           nm->method()->is_native() &&
-           nm->method()->is_synchronized(),
-           "should not call this otherwise");
-    nm = (nmethod*) _cb;
-  }
-  int byte_offset = in_bytes(nm->compiled_synchronized_native_basic_lock_owner_sp_offset());
+oop frame::get_native_receiver() {
+  nmethod* nm = (nmethod*)_cb;
+  assert(_cb != NULL && _cb->is_nmethod() && nm->method()->is_native(),
+         "Should not call this unless it's a native nmethod");
+  int byte_offset = in_bytes(nm->native_receiver_sp_offset());
   assert(byte_offset >= 0, "should not see invalid offset");
   oop owner = ((oop*) sp())[byte_offset / wordSize];
   assert( Universe::heap()->is_in(owner), "bad receiver" );

src/share/vm/runtime/frame.hpp

@@ -254,10 +254,10 @@ class frame VALUE_OBJ_CLASS_SPEC {
 
   // Return the monitor owner and BasicLock for compiled synchronized
   // native methods so that biased locking can revoke the receiver's
-  // bias if necessary. Takes optional nmethod for this frame as
-  // argument to avoid performing repeated lookups in code cache.
-  BasicLock* compiled_synchronized_native_monitor      (nmethod* nm = NULL);
-  oop        compiled_synchronized_native_monitor_owner(nmethod* nm = NULL);
+  // bias if necessary.  This is also used by JVMTI's GetLocalInstance method
+  // (via VM_GetReceiver) to retrieve the receiver from a native wrapper frame.
+  BasicLock* get_native_monitor();
+  oop        get_native_receiver();
 
   // Find receiver for an invoke when arguments are just pushed on stack (i.e., callee stack-frame is
   // not setup)

src/share/vm/runtime/vframe_hp.cpp

@@ -207,8 +207,8 @@ GrowableArray<MonitorInfo*>* compiledVFrame::monitors() const {
     GrowableArray<MonitorInfo*> *monitors = new GrowableArray<MonitorInfo*>(1);
     // Casting away const
     frame& fr = (frame&) _fr;
-    MonitorInfo* info = new MonitorInfo(fr.compiled_synchronized_native_monitor_owner(nm),
-                                        fr.compiled_synchronized_native_monitor(nm), false, false);
+    MonitorInfo* info = new MonitorInfo(
+        fr.get_native_receiver(), fr.get_native_monitor(), false, false);
     monitors->push(info);
     return monitors;
   }