8333819: Move embedded external addresses from relocation info into separate global table

Reviewed-by: dlong

src/hotspot/share/code/nmethod.cpp

@@ -3996,6 +3996,7 @@ void nmethod::print_statistics() {
   DebugInformationRecorder::print_statistics();
   pc_nmethod_stats.print_pc_stats();
   Dependencies::print_statistics();
+  ExternalsRecorder::print_statistics();
   if (xtty != nullptr)  xtty->tail("statistics");
 }
 

src/hotspot/share/code/nmethod.hpp

@@ -705,6 +705,7 @@ public:
 
   void copy_values(GrowableArray<jobject>* oops);
   void copy_values(GrowableArray<Metadata*>* metadata);
+  void copy_values(GrowableArray<address>* metadata) {} // Nothing to do
 
   // Relocation support
 private:

src/hotspot/share/code/oopRecorder.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -31,6 +31,7 @@
 #include "memory/allocation.inline.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/jniHandles.inline.hpp"
+#include "runtime/mutexLocker.hpp"
 #include "utilities/copy.hpp"
 
 #ifdef ASSERT
@@ -211,3 +212,46 @@ OopRecorder::OopRecorder(Arena* arena, bool deduplicate): _oops(arena), _metadat
     _object_lookup = nullptr;
   }
 }
+
+// Explicitly instantiate
+template class ValueRecorder<address>;
+
+ExternalsRecorder* ExternalsRecorder::_recorder = nullptr;
+
+ExternalsRecorder::ExternalsRecorder(): _arena(mtCode), _externals(&_arena) {}
+
+void ExternalsRecorder_init() {
+  ExternalsRecorder::initialize();
+}
+
+void ExternalsRecorder::initialize() {
+  // After Mutex and before CodeCache are initialized
+  assert(_recorder == nullptr, "should initialize only once");
+  _recorder = new ExternalsRecorder();
+}
+
+int ExternalsRecorder::find_index(address adr) {
+  MutexLocker ml(ExternalsRecorder_lock, Mutex::_no_safepoint_check_flag);
+  assert(_recorder != nullptr, "sanity");
+  return _recorder->_externals.find_index(adr);
+}
+
+address ExternalsRecorder::at(int index) {
+  // find_index() may resize array by reallocating it and freeing old,
+  // we need loock here to make sure we not accessing to old freed array.
+  MutexLocker ml(ExternalsRecorder_lock, Mutex::_no_safepoint_check_flag);
+  assert(_recorder != nullptr, "sanity");
+  return _recorder->_externals.at(index);
+}
+
+int ExternalsRecorder::count() {
+  MutexLocker ml(ExternalsRecorder_lock, Mutex::_no_safepoint_check_flag);
+  assert(_recorder != nullptr, "sanity");
+  return _recorder->_externals.count();
+}
+
+#ifndef PRODUCT
+void ExternalsRecorder::print_statistics() {
+  tty->print_cr("External addresses table: %d entries", count());
+}
+#endif

src/hotspot/share/code/oopRecorder.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -186,7 +186,7 @@ class OopRecorder : public ResourceObj {
   int allocate_oop_index(jobject h) {
     return _oops.allocate_index(h);
   }
-  virtual int find_index(jobject h) {
+  int find_index(jobject h) {
     return _object_lookup != nullptr ? _object_lookup->find_index(h, this) : _oops.find_index(h);
   }
   jobject oop_at(int index) {
@@ -203,7 +203,7 @@ class OopRecorder : public ResourceObj {
   int allocate_metadata_index(Metadata* oop) {
     return _metadata.allocate_index(oop);
   }
-  virtual int find_index(Metadata* h) {
+  int find_index(Metadata* h) {
     return _metadata.find_index(h);
   }
   Metadata* metadata_at(int index) {
@@ -243,5 +243,20 @@ class OopRecorder : public ResourceObj {
 #endif
 };
 
+// Class is used to record and retrive external addresses
+// for Relocation info in compiled code and stubs.
+class ExternalsRecorder : public CHeapObj<mtCode> {
+ private:
+  Arena  _arena;
+  ValueRecorder<address> _externals;
+  static ExternalsRecorder* _recorder;
+  ExternalsRecorder();
+ public:
+  static void initialize();
+  static int find_index(address adr);
+  static address at(int index);
+  static int count();
+  static void print_statistics() PRODUCT_RETURN;
+};
 
 #endif // SHARE_CODE_OOPRECORDER_HPP

src/hotspot/share/code/relocInfo.cpp

@@ -454,27 +454,15 @@ void trampoline_stub_Relocation::unpack_data() {
 
 void external_word_Relocation::pack_data_to(CodeSection* dest) {
   short* p = (short*) dest->locs_end();
-#ifndef _LP64
-  p = pack_1_int_to(p, (int32_t) (intptr_t)_target);
-#else
-  jlong t = (jlong) _target;
-  int32_t lo = low(t);
-  int32_t hi = high(t);
-  p = pack_2_ints_to(p, lo, hi);
-#endif /* _LP64 */
+  int index = ExternalsRecorder::find_index(_target);
+  p = pack_1_int_to(p, index);
   dest->set_locs_end((relocInfo*) p);
 }
 
 
 void external_word_Relocation::unpack_data() {
-#ifndef _LP64
-  _target = (address) (intptr_t)unpack_1_int();
-#else
-  jint lo, hi;
-  unpack_2_ints(lo, hi);
-  jlong t = jlong_from(hi, lo);;
-  _target = (address) t;
-#endif /* _LP64 */
+  int index = unpack_1_int();
+  _target = ExternalsRecorder::at(index);
 }
 
 

src/hotspot/share/runtime/init.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -57,6 +57,7 @@ void mutex_init();
 void universe_oopstorage_init();
 void perfMemory_init();
 void SuspendibleThreadSet_init();
+void ExternalsRecorder_init(); // After mutex_init() and before CodeCache_init
 
 // Initialization done by Java thread in init_globals()
 void management_init();
@@ -107,6 +108,7 @@ void vm_init_globals() {
   universe_oopstorage_init();
   perfMemory_init();
   SuspendibleThreadSet_init();
+  ExternalsRecorder_init(); // After mutex_init() and before CodeCache_init
 }
 
 

src/hotspot/share/runtime/mutexLocker.cpp

@@ -123,6 +123,8 @@ Monitor* JfrThreadSampler_lock        = nullptr;
 
 Mutex*   CodeHeapStateAnalytics_lock  = nullptr;
 
+Mutex*   ExternalsRecorder_lock       = nullptr;
+
 Monitor* ContinuationRelativize_lock  = nullptr;
 
 Mutex*   Metaspace_lock               = nullptr;
@@ -328,6 +330,9 @@ void mutex_init() {
   MUTEX_DEFL(CodeCache_lock                 , PaddedMonitor, VtableStubs_lock);
   MUTEX_DEFL(NMethodState_lock              , PaddedMutex  , CodeCache_lock);
 
+  // tty_lock is held when printing nmethod and its relocations which use this lock.
+  MUTEX_DEFL(ExternalsRecorder_lock         , PaddedMutex  , tty_lock);
+
   MUTEX_DEFL(Threads_lock                   , PaddedMonitor, CompileThread_lock, true);
   MUTEX_DEFL(Compile_lock                   , PaddedMutex  , MethodCompileQueue_lock);
   MUTEX_DEFL(Heap_lock                      , PaddedMonitor, AdapterHandlerLibrary_lock);

src/hotspot/share/runtime/mutexLocker.hpp

@@ -142,6 +142,8 @@ extern Mutex*   ClassLoaderDataGraph_lock;       // protects CLDG list, needed f
 extern Mutex*   CodeHeapStateAnalytics_lock;     // lock print functions against concurrent analyze functions.
                                                  // Only used locally in PrintCodeCacheLayout processing.
 
+extern Mutex*   ExternalsRecorder_lock;          // used to guard access to the external addresses table
+
 extern Monitor* ContinuationRelativize_lock;
 
 #if INCLUDE_JVMCI