8279500: Remove FileMapHeader::_heap_obj_roots

Reviewed-by: minqi, ccheung

Author: iklam

src/hotspot/share/cds/filemap.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2022, 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
@@ -273,7 +273,6 @@ void FileMapHeader::populate(FileMapInfo *info, size_t core_region_alignment,
 
   if (!DynamicDumpSharedSpaces) {
     set_shared_path_table(info->_shared_path_table);
-    CDS_JAVA_HEAP_ONLY(_heap_obj_roots = CompressedOops::encode(HeapShared::roots());)
   }
 }
 
@@ -2097,7 +2096,6 @@ void FileMapInfo::map_heap_regions_impl() {
                          /*is_open_archive=*/ true,
                          &open_heap_regions, &num_open_heap_regions)) {
       HeapShared::set_open_regions_mapped();
-      HeapShared::set_roots(header()->heap_obj_roots());
     }
   }
 }

src/hotspot/share/cds/filemap.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2022, 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
@@ -232,7 +232,6 @@ class FileMapHeader: private CDSFileMapHeaderBase {
                                         // some expensive operations.
   bool   _use_full_module_graph;        // Can we use the full archived module graph?
   size_t _ptrmap_size_in_bits;          // Size of pointer relocation bitmap
-  narrowOop _heap_obj_roots;            // An objArray that stores all the roots of archived heap objects
   char* from_mapped_offset(size_t offset) const {
     return mapped_base_address() + offset;
   }
@@ -279,14 +278,12 @@ class FileMapHeader: private CDSFileMapHeaderBase {
   jshort app_module_paths_start_index()    const { return _app_module_paths_start_index; }
   jshort app_class_paths_start_index()     const { return _app_class_paths_start_index; }
   jshort num_module_paths()                const { return _num_module_paths; }
-  narrowOop heap_obj_roots()               const { return _heap_obj_roots; }
 
   void set_has_platform_or_app_classes(bool v)   { _has_platform_or_app_classes = v; }
   void set_cloned_vtables(char* p)               { set_as_offset(p, &_cloned_vtables_offset); }
   void set_serialized_data(char* p)              { set_as_offset(p, &_serialized_data_offset); }
   void set_ptrmap_size_in_bits(size_t s)         { _ptrmap_size_in_bits = s; }
   void set_mapped_base_address(char* p)          { _mapped_base_address = p; }
-  void set_heap_obj_roots(narrowOop r)           { _heap_obj_roots = r; }
   void copy_base_archive_name(const char* name);
 
   void set_shared_path_table(SharedPathTable table) {
@@ -413,8 +410,6 @@ class FileMapInfo : public CHeapObj<mtInternal> {
   void set_requested_base(char* b)                  { header()->set_requested_base(b); }
   char* requested_base_address()           const    { return header()->requested_base_address(); }
 
-  narrowOop heap_obj_roots()               const    { return header()->heap_obj_roots(); }
-
   class DynamicArchiveHeader* dynamic_header() const {
     assert(!is_static(), "must be");
     return (DynamicArchiveHeader*)header();

src/hotspot/share/cds/heapShared.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2022, 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
@@ -128,7 +128,6 @@ const static int num_fmg_open_archive_subgraph_entry_fields =
   sizeof(fmg_open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 
 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = NULL;
-narrowOop HeapShared::_roots_narrow;
 OopHandle HeapShared::_roots;
 
 #ifdef ASSERT
@@ -152,7 +151,6 @@ void HeapShared::fixup_regions() {
     fill_failed_loaded_region();
   }
   if (is_fully_available()) {
-    _roots = OopHandle(Universe::vm_global(), decode_from_archive(_roots_narrow));
     if (!MetaspaceShared::use_full_module_graph()) {
       // Need to remove all the archived java.lang.Module objects from HeapShared::roots().
       ClassLoaderDataShared::clear_archived_oops();
@@ -236,12 +234,6 @@ objArrayOop HeapShared::roots() {
   return roots;
 }
 
-void HeapShared::set_roots(narrowOop roots) {
-  assert(UseSharedSpaces, "runtime only");
-  assert(is_fully_available(), "must be");
-  _roots_narrow = roots;
-}
-
 // Returns an objArray that contains all the roots of the archived objects
 oop HeapShared::get_root(int index, bool clear) {
   assert(index >= 0, "sanity");
@@ -670,7 +662,23 @@ void HeapShared::write_subgraph_info_table() {
   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 }
 
-void HeapShared::serialize_subgraph_info_table_header(SerializeClosure* soc) {
+void HeapShared::serialize(SerializeClosure* soc) {
+  oop roots_oop = NULL;
+
+  if (soc->reading()) {
+    soc->do_oop(&roots_oop); // read from archive
+    assert(oopDesc::is_oop_or_null(roots_oop), "is oop");
+    // Create an OopHandle only if we have actually mapped or loaded the roots
+    if (roots_oop != NULL) {
+      assert(HeapShared::is_fully_available(), "must be");
+      _roots = OopHandle(Universe::vm_global(), roots_oop);
+    }
+  } else {
+    // writing
+    roots_oop = roots();
+    soc->do_oop(&roots_oop); // write to archive
+  }
+
   _run_time_subgraph_info_table.serialize_header(soc);
 }
 
@@ -1695,7 +1703,6 @@ bool HeapShared::load_heap_regions(FileMapInfo* mapinfo) {
 
   init_loaded_heap_relocation(loaded_regions, num_loaded_regions);
   _is_loaded = true;
-  set_roots(mapinfo->heap_obj_roots());
 
   return true;
 }

src/hotspot/share/cds/heapShared.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2022, 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
@@ -310,7 +310,6 @@ class HeapShared: AllStatic {
   static SeenObjectsTable *_seen_objects_table;
 
   static GrowableArrayCHeap<oop, mtClassShared>* _pending_roots;
-  static narrowOop _roots_narrow;
   static OopHandle _roots;
 
   static void init_seen_objects_table() {
@@ -418,7 +417,6 @@ class HeapShared: AllStatic {
   static oop get_root(int index, bool clear=false);
 
   // Run-time only
-  static void set_roots(narrowOop roots);
   static void clear_root(int index);
 #endif // INCLUDE_CDS_JAVA_HEAP
 
@@ -468,7 +466,7 @@ class HeapShared: AllStatic {
 
   static void init_for_dumping(TRAPS) NOT_CDS_JAVA_HEAP_RETURN;
   static void write_subgraph_info_table() NOT_CDS_JAVA_HEAP_RETURN;
-  static void serialize_subgraph_info_table_header(SerializeClosure* soc) NOT_CDS_JAVA_HEAP_RETURN;
+  static void serialize(SerializeClosure* soc) NOT_CDS_JAVA_HEAP_RETURN;
 };
 
 #if INCLUDE_CDS_JAVA_HEAP

src/hotspot/share/cds/metaspaceShared.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2022, 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
@@ -384,7 +384,7 @@ void MetaspaceShared::serialize(SerializeClosure* soc) {
   // Dump/restore the symbol/string/subgraph_info tables
   SymbolTable::serialize_shared_table_header(soc);
   StringTable::serialize_shared_table_header(soc);
-  HeapShared::serialize_subgraph_info_table_header(soc);
+  HeapShared::serialize(soc);
   SystemDictionaryShared::serialize_dictionary_headers(soc);
 
   InstanceMirrorKlass::serialize_offsets(soc);

src/hotspot/share/include/cds.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2022, 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
@@ -39,7 +39,7 @@
 #define CDS_ARCHIVE_MAGIC 0xf00baba2
 #define CDS_DYNAMIC_ARCHIVE_MAGIC 0xf00baba8
 #define CDS_GENERIC_HEADER_SUPPORTED_MIN_VERSION 13
-#define CURRENT_CDS_ARCHIVE_VERSION 13
+#define CURRENT_CDS_ARCHIVE_VERSION 14
 
 typedef struct CDSFileMapRegion {
   int     _crc;               // CRC checksum of this region.