8364202: CDS without G1 gives build error in slowdebug, asserts in fastdebug

Reviewed-by: ccheung, iklam

src/hotspot/share/cds/metaspaceShared.cpp

@@ -1603,8 +1603,7 @@ MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, File
 
       // Set up compressed Klass pointer encoding: the encoding range must
       //  cover both archive and class space.
-      const address encoding_base = (address)mapped_base_address;
-      const address klass_range_start = encoding_base + prot_zone_size;
+      const address klass_range_start = (address)mapped_base_address;
       const size_t klass_range_size = (address)class_space_rs.end() - klass_range_start;
       if (INCLUDE_CDS_JAVA_HEAP || UseCompactObjectHeaders) {
         // The CDS archive may contain narrow Klass IDs that were precomputed at archive generation time:
@@ -1615,13 +1614,19 @@ MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, File
         // mapping start (including protection zone), shift should be the shift used at archive generation time.
         CompressedKlassPointers::initialize_for_given_encoding(
           klass_range_start, klass_range_size,
-          encoding_base, ArchiveBuilder::precomputed_narrow_klass_shift() // precomputed encoding, see ArchiveBuilder
+          klass_range_start, ArchiveBuilder::precomputed_narrow_klass_shift() // precomputed encoding, see ArchiveBuilder
         );
+        assert(CompressedKlassPointers::base() == klass_range_start, "must be");
       } else {
         // Let JVM freely choose encoding base and shift
         CompressedKlassPointers::initialize(klass_range_start, klass_range_size);
+        assert(CompressedKlassPointers::base() == nullptr ||
+               CompressedKlassPointers::base() == klass_range_start, "must be");
+      }
+      // Establish protection zone, but only if we need one
+      if (CompressedKlassPointers::base() == klass_range_start) {
+        CompressedKlassPointers::establish_protection_zone(klass_range_start, prot_zone_size);
       }
-      CompressedKlassPointers::establish_protection_zone(encoding_base, prot_zone_size);
 
       // map_or_load_heap_region() compares the current narrow oop and klass encodings
       // with the archived ones, so it must be done after all encodings are determined.

src/hotspot/share/classfile/classLoaderDataShared.hpp

@@ -35,8 +35,9 @@ class SerializeClosure;
 
 class ClassLoaderDataShared : AllStatic {
   static bool _full_module_graph_loaded;
-  static void ensure_module_entry_table_exists(oop class_loader);
+  CDS_JAVA_HEAP_ONLY(static void ensure_module_entry_table_exists(oop class_loader);)
 public:
+#if INCLUDE_CDS_JAVA_HEAP
   static void ensure_module_entry_tables_exist();
   static void allocate_archived_tables();
   static void iterate_symbols(MetaspaceClosure* closure);
@@ -49,6 +50,7 @@ public:
   static void restore_java_system_loader_from_archive(ClassLoaderData* loader_data);
   static ModuleEntry* archived_boot_unnamed_module();
   static ModuleEntry* archived_unnamed_module(ClassLoaderData* loader_data);
+#endif // INCLUDE_CDS_JAVA_HEAP
   static bool is_full_module_graph_loaded() { return _full_module_graph_loaded; }
 };
 

src/hotspot/share/memory/universe.cpp

@@ -909,9 +909,11 @@ jint universe_init() {
   ClassLoaderData::init_null_class_loader_data();
 
 #if INCLUDE_CDS
+#if INCLUDE_CDS_JAVA_HEAP
   if (CDSConfig::is_using_full_module_graph()) {
     ClassLoaderDataShared::restore_archived_entries_for_null_class_loader_data();
   }
+#endif // INCLUDE_CDS_JAVA_HEAP
   if (CDSConfig::is_dumping_archive()) {
     CDSConfig::prepare_for_dumping();
   }

src/hotspot/share/oops/compressedKlass.cpp

@@ -141,7 +141,8 @@ void CompressedKlassPointers::calc_lowest_highest_narrow_klass_id() {
   address lowest_possible_klass_location = _klass_range_start;
 
   // A Klass will never be placed at the Encoding range start, since that would translate to a narrowKlass=0, which
-  // is disallowed. Note that both Metaspace and CDS prvent allocation at the first address for this reason.
+  // is disallowed. If the encoding range starts at the klass range start, both Metaspace and CDS establish an
+  // mprotected zone for this reason (see establish_protection_zone).
   if (lowest_possible_klass_location == _base) {
     lowest_possible_klass_location += klass_alignment_in_bytes();
   }

src/hotspot/share/oops/compressedKlass.hpp

@@ -124,7 +124,7 @@ class CompressedKlassPointers : public AllStatic {
   static address _base;
   static int _shift;
 
-  // Start and end of the Klass Range.
+  // Start and end of the Klass Range. Start includes the protection zone if one exists.
   // Note: guaranteed to be aligned to 1<<shift (klass_alignment_in_bytes)
   static address _klass_range_start;
   static address _klass_range_end;