8261090: Store old classfiles in static CDS archive

Reviewed-by: iklam, minqi

src/hotspot/share/classfile/classFileParser.cpp

@@ -5920,18 +5920,6 @@ void ClassFileParser::parse_stream(const ClassFileStream* const stream,
   _minor_version = stream->get_u2_fast();
   _major_version = stream->get_u2_fast();
 
-  if (DumpSharedSpaces && _major_version < JAVA_6_VERSION) {
-    ResourceMark rm;
-    warning("Pre JDK 6 class not supported by CDS: %u.%u %s",
-            _major_version,  _minor_version, _class_name->as_C_string());
-    Exceptions::fthrow(
-      THREAD_AND_LOCATION,
-      vmSymbols::java_lang_UnsupportedClassVersionError(),
-      "Unsupported major.minor version for dump time %u.%u",
-      _major_version,
-      _minor_version);
-  }
-
   // Check version numbers - we check this even with verifier off
   verify_class_version(_major_version, _minor_version, _class_name, CHECK);
 

src/hotspot/share/classfile/systemDictionaryShared.cpp

@@ -1380,18 +1380,28 @@ bool SystemDictionaryShared::should_be_excluded(InstanceKlass* k) {
     //    class loader doesn't expect it.
     if (has_class_failed_verification(k)) {
       warn_excluded(k, "Failed verification");
+      return true;
     } else {
-      warn_excluded(k, "Not linked");
+      if (!MetaspaceShared::is_old_class(k)) {
+        warn_excluded(k, "Not linked");
+        return true;
+      }
     }
-    return true;
   }
-  if (k->major_version() < 50 /*JAVA_6_VERSION*/) {
+  if (DynamicDumpSharedSpaces && k->major_version() < 50 /*JAVA_6_VERSION*/) {
+    // In order to support old classes during dynamic dump, class rewriting needs to
+    // be reverted. This would result in more complex code and testing but not much gain.
     ResourceMark rm;
     log_warning(cds)("Pre JDK 6 class not supported by CDS: %u.%u %s",
                      k->major_version(),  k->minor_version(), k->name()->as_C_string());
     return true;
   }
 
+  if (MetaspaceShared::is_old_class(k) && k->is_linked()) {
+    warn_excluded(k, "Old class has been linked");
+    return true;
+  }
+
   InstanceKlass* super = k->java_super();
   if (super != NULL && should_be_excluded(super)) {
     ResourceMark rm;

src/hotspot/share/classfile/verifier.cpp

@@ -285,7 +285,9 @@ bool Verifier::is_eligible_for_verification(InstanceKlass* klass, bool should_ve
     // already been rewritten to contain constant pool cache indices,
     // which the verifier can't understand.
     // Shared classes shouldn't have stackmaps either.
-    !klass->is_shared() &&
+    // However, bytecodes for shared old classes can be verified because
+    // they have not been rewritten.
+    !(klass->is_shared() && klass->is_rewritten()) &&
 
     // As of the fix for 4486457 we disable verification for all of the
     // dynamically-generated bytecodes associated with the 1.4

src/hotspot/share/interpreter/rewriter.cpp

@@ -28,6 +28,7 @@
 #include "interpreter/interpreter.hpp"
 #include "interpreter/rewriter.hpp"
 #include "memory/metadataFactory.hpp"
+#include "memory/metaspaceShared.hpp"
 #include "memory/resourceArea.hpp"
 #include "oops/constantPool.hpp"
 #include "oops/generateOopMap.hpp"
@@ -567,8 +568,9 @@ void Rewriter::rewrite_bytecodes(TRAPS) {
 }
 
 void Rewriter::rewrite(InstanceKlass* klass, TRAPS) {
-  if (!DumpSharedSpaces) {
-    assert(!klass->is_shared(), "archive methods must not be rewritten at run time");
+  if (klass->is_shared()) {
+    assert(!klass->is_rewritten(), "rewritten shared classes cannot be rewritten again");
+    assert(MetaspaceShared::is_old_class(klass), "only shared old classes aren't rewritten");
   }
   ResourceMark rm(THREAD);
   constantPoolHandle cpool(THREAD, klass->constants());

src/hotspot/share/memory/metaspaceShared.cpp

@@ -389,7 +389,9 @@ static void rewrite_nofast_bytecode(const methodHandle& method) {
 void MetaspaceShared::rewrite_nofast_bytecodes_and_calculate_fingerprints(Thread* thread, InstanceKlass* ik) {
   for (int i = 0; i < ik->methods()->length(); i++) {
     methodHandle m(thread, ik->methods()->at(i));
-    rewrite_nofast_bytecode(m);
+    if (!is_old_class(ik)) {
+      rewrite_nofast_bytecode(m);
+    }
     Fingerprinter fp(m);
     // The side effect of this call sets method's fingerprint field.
     fp.fingerprint();
@@ -578,9 +580,31 @@ class CollectCLDClosure : public CLDClosure {
   ClassLoaderData* cld_at(int index) { return _loaded_cld.at(index); }
 };
 
+// Check if a class or its super class/interface is old.
+bool MetaspaceShared::is_old_class(InstanceKlass* ik) {
+  if (ik == NULL) {
+    return false;
+  }
+  if (ik->major_version() < 50 /*JAVA_6_VERSION*/) {
+    return true;
+  }
+  if (is_old_class(ik->java_super())) {
+    return true;
+  }
+  Array<InstanceKlass*>* interfaces = ik->local_interfaces();
+  int len = interfaces->length();
+  for (int i = 0; i < len; i++) {
+    if (is_old_class(interfaces->at(i))) {
+      return true;
+    }
+  }
+  return false;
+}
+
 bool MetaspaceShared::linking_required(InstanceKlass* ik) {
+  // For static CDS dump, do not link old classes.
   // For dynamic CDS dump, only link classes loaded by the builtin class loaders.
-  return DumpSharedSpaces ? true : !ik->is_shared_unregistered_class();
+  return DumpSharedSpaces ? !MetaspaceShared::is_old_class(ik) : !ik->is_shared_unregistered_class();
 }
 
 bool MetaspaceShared::link_class_for_cds(InstanceKlass* ik, TRAPS) {
@@ -760,7 +784,7 @@ bool MetaspaceShared::try_link_class(Thread* current, InstanceKlass* ik) {
   ExceptionMark em(current);
   Thread* THREAD = current; // For exception macros.
   Arguments::assert_is_dumping_archive();
-  if (ik->is_loaded() && !ik->is_linked() &&
+  if (ik->is_loaded() && !ik->is_linked() && !MetaspaceShared::is_old_class(ik) &&
       !SystemDictionaryShared::has_class_failed_verification(ik)) {
     bool saved = BytecodeVerificationLocal;
     if (ik->is_shared_unregistered_class() && ik->class_loader() == NULL) {
@@ -806,7 +830,9 @@ void VM_PopulateDumpSharedSpace::dump_java_heap_objects(GrowableArray<Klass*>* k
     Klass* k = klasses->at(i);
     if (k->is_instance_klass()) {
       InstanceKlass* ik = InstanceKlass::cast(k);
-      ik->constants()->add_dumped_interned_strings();
+      if (ik->is_linked()) {
+        ik->constants()->add_dumped_interned_strings();
+      }
     }
   }
   if (_extra_interned_strings != NULL) {

src/hotspot/share/memory/metaspaceShared.hpp

@@ -137,6 +137,7 @@ class MetaspaceShared : AllStatic {
   static void link_and_cleanup_shared_classes(TRAPS) NOT_CDS_RETURN;
   static bool link_class_for_cds(InstanceKlass* ik, TRAPS) NOT_CDS_RETURN_(false);
   static bool linking_required(InstanceKlass* ik) NOT_CDS_RETURN_(false);
+  static bool is_old_class(InstanceKlass* ik);
 
 #if INCLUDE_CDS
   // Alignment for the 3 core CDS regions (MC/RW/RO) only.

src/hotspot/share/oops/constMethod.cpp

@@ -405,7 +405,11 @@ void ConstMethod::copy_annotations_from(ClassLoaderData* loader_data, ConstMetho
 void ConstMethod::metaspace_pointers_do(MetaspaceClosure* it) {
   log_trace(cds)("Iter(ConstMethod): %p", this);
 
-  it->push(&_constants);
+  if (!method()->method_holder()->is_rewritten()) {
+    it->push(&_constants, MetaspaceClosure::_writable);
+  } else {
+    it->push(&_constants);
+  }
   it->push(&_stackmap_data);
   if (has_method_annotations()) {
     it->push(method_annotations_addr());
@@ -419,7 +423,6 @@ void ConstMethod::metaspace_pointers_do(MetaspaceClosure* it) {
   if (has_default_annotations()) {
       it->push(default_annotations_addr());
   }
-  ConstMethod* this_ptr = this;
 }
 
 // Printing

src/hotspot/share/oops/constantPool.cpp

@@ -353,6 +353,9 @@ void ConstantPool::add_dumped_interned_strings() {
 
 // CDS support. Create a new resolved_references array.
 void ConstantPool::restore_unshareable_info(TRAPS) {
+  if (!_pool_holder->is_linked() && !_pool_holder->is_rewritten()) {
+    return;
+  }
   assert(is_constantPool(), "ensure C++ vtable is restored");
   assert(on_stack(), "should always be set for shared constant pools");
   assert(is_shared(), "should always be set for shared constant pools");
@@ -390,6 +393,9 @@ void ConstantPool::restore_unshareable_info(TRAPS) {
 }
 
 void ConstantPool::remove_unshareable_info() {
+  if (!_pool_holder->is_linked() && _pool_holder->is_shared_old_klass()) {
+    return;
+  }
   // Resolved references are not in the shared archive.
   // Save the length for restoration.  It is not necessarily the same length
   // as reference_map.length() if invokedynamic is saved. It is needed when

src/hotspot/share/oops/instanceKlass.cpp

@@ -2454,7 +2454,11 @@ void InstanceKlass::metaspace_pointers_do(MetaspaceClosure* it) {
 
   it->push(&_annotations);
   it->push((Klass**)&_array_klasses);
-  it->push(&_constants);
+  if (!is_rewritten()) {
+    it->push(&_constants, MetaspaceClosure::_writable);
+  } else {
+    it->push(&_constants);
+  }
   it->push(&_inner_classes);
 #if INCLUDE_JVMTI
   it->push(&_previous_versions);
@@ -2491,6 +2495,12 @@ void InstanceKlass::metaspace_pointers_do(MetaspaceClosure* it) {
 }
 
 void InstanceKlass::remove_unshareable_info() {
+
+  if (MetaspaceShared::is_old_class(this)) {
+    // Set the old class bit.
+    set_is_shared_old_klass();
+  }
+
   Klass::remove_unshareable_info();
 
   if (SystemDictionaryShared::has_class_failed_verification(this)) {

src/hotspot/share/oops/klass.hpp

@@ -177,7 +177,8 @@ class Klass : public Metadata {
   u2     _shared_class_flags;
   enum {
     _archived_lambda_proxy_is_available = 2,
-    _has_value_based_class_annotation = 4
+    _has_value_based_class_annotation = 4,
+    _is_shared_old_klass = 8
   };
 #endif
 
@@ -333,6 +334,14 @@ class Klass : public Metadata {
     NOT_CDS(return false;)
   }
 
+  void set_is_shared_old_klass() {
+    CDS_ONLY(_shared_class_flags |= _is_shared_old_klass;)
+  }
+  bool is_shared_old_klass() const {
+    CDS_ONLY(return (_shared_class_flags & _is_shared_old_klass) != 0;)
+    NOT_CDS(return false;)
+  }
+
 
   // Obtain the module or package for this class
   virtual ModuleEntry* module() const = 0;

src/hotspot/share/oops/klassVtable.cpp

@@ -51,7 +51,7 @@ inline InstanceKlass* klassVtable::ik() const {
 }
 
 bool klassVtable::is_preinitialized_vtable() {
-  return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
+  return _klass->is_shared() && !MetaspaceShared::remapped_readwrite() && !_klass->is_shared_old_klass();
 }
 
 
@@ -1093,7 +1093,8 @@ void itableMethodEntry::initialize(Method* m) {
 
 #ifdef ASSERT
   if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
-     !MetaspaceShared::remapped_readwrite()) {
+     !MetaspaceShared::remapped_readwrite() &&
+     !MetaspaceShared::is_old_class(m->method_holder())) {
     // At runtime initialize_itable is rerun as part of link_class_impl()
     // for a shared class loaded by the non-boot loader.
     // The dumptime itable method entry should be the same as the runtime entry.

src/hotspot/share/oops/method.cpp

@@ -344,11 +344,13 @@ Symbol* Method::klass_name() const {
 void Method::metaspace_pointers_do(MetaspaceClosure* it) {
   log_trace(cds)("Iter(Method): %p", this);
 
-  it->push(&_constMethod);
+  if (!method_holder()->is_rewritten()) {
+    it->push(&_constMethod, MetaspaceClosure::_writable);
+  } else {
+    it->push(&_constMethod);
+  }
   it->push(&_method_data);
   it->push(&_method_counters);
-
-  Method* this_ptr = this;
 }
 
 // Attempt to return method to original state.  Clear any pointers
@@ -362,7 +364,7 @@ void Method::remove_unshareable_info() {
 }
 
 void Method::set_vtable_index(int index) {
-  if (is_shared() && !MetaspaceShared::remapped_readwrite()) {
+  if (is_shared() && !MetaspaceShared::remapped_readwrite() && !method_holder()->is_shared_old_klass()) {
     // At runtime initialize_vtable is rerun as part of link_class_impl()
     // for a shared class loaded by the non-boot loader to obtain the loader
     // constraints based on the runtime classloaders' context.
@@ -373,7 +375,7 @@ void Method::set_vtable_index(int index) {
 }
 
 void Method::set_itable_index(int index) {
-  if (is_shared() && !MetaspaceShared::remapped_readwrite()) {
+  if (is_shared() && !MetaspaceShared::remapped_readwrite() && !method_holder()->is_shared_old_klass()) {
     // At runtime initialize_itable is rerun as part of link_class_impl()
     // for a shared class loaded by the non-boot loader to obtain the loader
     // constraints based on the runtime classloaders' context. The dumptime

test/hotspot/jtreg/runtime/cds/appcds/LambdaWithOldClass.java

@@ -68,7 +68,7 @@ public static void main(String[] args) throws Exception {
             .addSuffix(mainClass);
         OutputAnalyzer output = CDSTestUtils.runWithArchive(runOpts);
         output.shouldContain("[class,load] LambdaWithOldClassApp source: shared objects file")
-              .shouldMatch(".class.load. LambdaWithOldClassApp[$][$]Lambda[$].*/0x.*source:.*LambdaWithOldClassApp")
+              .shouldMatch(".class.load. LambdaWithOldClassApp[$][$]Lambda[$].*/0x.*source:.*shared objects file")
               .shouldHaveExitValue(0);
     }
 }

test/hotspot/jtreg/runtime/cds/appcds/OldClassTest.java

@@ -24,7 +24,7 @@
 
 /*
  * @test
- * @summary classes with major version < JDK_6 (50) should not be included in CDS
+ * @summary CDS support of old classes with major version < JDK_6 (50) for static archive.
  * @requires vm.cds
  * @library /test/lib
  * @modules java.base/jdk.internal.org.objectweb.asm
@@ -35,6 +35,7 @@
 
 import java.io.File;
 import java.io.FileOutputStream;
+import jdk.test.lib.cds.CDSTestUtils;
 import jdk.test.lib.process.OutputAnalyzer;
 import java.nio.file.Files;
 
@@ -55,26 +56,47 @@ public static void main(String[] args) throws Exception {
     }
 
     String appClasses[] = TestCommon.list("Hello");
+    boolean dynamicMode = CDSTestUtils.DYNAMIC_DUMP;
 
     // CASE 1: pre-JDK 6 compiled classes should be excluded from the dump
-    OutputAnalyzer output = TestCommon.dump(jar, appClasses);
-    TestCommon.checkExecReturn(output, 0, true, "Pre JDK 6 class not supported by CDS");
+    OutputAnalyzer output = TestCommon.dump(jar, appClasses, "-Xlog:class+load,cds=debug");
+    TestCommon.checkExecReturn(output, 0,
+                               dynamicMode ? true : false,
+                               "Pre JDK 6 class not supported by CDS");
 
     TestCommon.run(
         "-cp", jar,
+        "-Xlog:class+load",
         "Hello")
-      .assertNormalExit("Hello Unicode world (Old)");
+      .assertNormalExit(out -> {
+          out.shouldContain("Hello Unicode world (Old)");
+          if (!dynamicMode) {
+              out.shouldContain("Hello source: shared objects file");
+          } else {
+              out.shouldMatch(".class.load. Hello source:.*OldClassTest_old.jar");
+          }
+      });
 
     // CASE 2: if we exlcude old version of this class, we should not pick up
     //         the newer version of this class in a subsequent classpath element.
     String classpath = jar + File.pathSeparator + jarSrcFile.getPath();
     output = TestCommon.dump(classpath, appClasses);
-    TestCommon.checkExecReturn(output, 0, true, "Pre JDK 6 class not supported by CDS");
+    TestCommon.checkExecReturn(output, 0,
+                               dynamicMode ? true : false,
+                               "Pre JDK 6 class not supported by CDS");
 
     TestCommon.run(
         "-cp", classpath,
+        "-Xlog:class+load",
         "Hello")
-      .assertNormalExit("Hello Unicode world (Old)");
+      .assertNormalExit(out -> {
+          out.shouldContain("Hello Unicode world (Old)");
+          if (!dynamicMode) {
+              out.shouldContain("Hello source: shared objects file");
+          } else {
+              out.shouldMatch(".class.load. Hello source:.*OldClassTest_old.jar");
+          }
+      });
   }
 
   static void createTestJarFile(File jarSrcFile, File jarFile) throws Exception {