JDK-8327246: added support to summarize AOT cache sharing usage

src/hotspot/share/oops/instanceKlass.cpp

@@ -2372,7 +2372,18 @@ void PrintClassClosure::do_klass(Klass* k)  {
     if (ik->is_rewritten()) buf[i++] = 'W';
     if (ik->is_contended()) buf[i++] = 'C';
     if (ik->has_been_redefined()) buf[i++] = 'R';
-    if (ik->in_aot_cache()) buf[i++] = 'S';
+    if (ik->in_aot_cache()) {
+      buf[i++] = 'S';
+
+      if (AOTMetaspace::in_aot_cache_static_region((void*)k)) {
+        _aot_statics++;
+        if (_location) buf[i++] = 's';
+      } else if (AOTMetaspace::in_aot_cache_dynamic_region((void*)k)) {
+        _aot_dynamics++;
+        if (_location) buf[i++] = 'd';
+      }
+    }
+
   }
   buf[i++] = '\0';
   _st->print("%-7s  ", buf);

src/hotspot/share/oops/instanceKlass.hpp

@@ -1211,6 +1211,9 @@ private:
   bool _verbose;
   bool _location;
 public:
+  unsigned int _aot_statics;
+  unsigned int _aot_dynamics;
+
   PrintClassClosure(outputStream* st, bool verbose, bool location);
 
   void do_klass(Klass* k);

src/hotspot/share/services/diagnosticCommand.cpp

@@ -25,6 +25,7 @@
 #include "cds/aotMetaspace.hpp"
 #include "cds/cds_globals.hpp"
 #include "cds/cdsConfig.hpp"
+#include "cds/filemap.hpp"
 #include "classfile/classLoaderDataGraph.hpp"
 #include "classfile/classLoaderHierarchyDCmd.hpp"
 #include "classfile/classLoaderStats.hpp"
@@ -957,9 +958,9 @@ ClassesDCmd::ClassesDCmd(outputStream* output, bool heap) :
            "W = methods rewritten, "
            "C = marked with @Contended annotation, "
            "R = has been redefined, "
-           "S = is shared class",
+           "S = is shared class (if -location then 's' indicates static 'd' indicates dynamic AOT cache)",
            "BOOLEAN", false, "false"),
-  _location("-location", "Print class file location url (if available)", "BOOLEAN", false, "false") {
+  _location("-location", "Print class file (and AOT cache) location url (if available)", "BOOLEAN", false, "false") {
   _dcmdparser.add_dcmd_option(&_verbose);
   _dcmdparser.add_dcmd_option(&_location);
 }
@@ -977,6 +978,13 @@ public:
   virtual void doit() {
     PrintClassClosure closure(_out, _verbose, _location);
     ClassLoaderDataGraph::classes_do(&closure);
+
+    if (_location) {
+      if (closure._aot_statics > 0)
+        _out->print_cr("\n%d classes shared from static cache: %s", closure._aot_statics, FileMapInfo::current_info()->full_path());
+      if (closure._aot_dynamics > 0)
+        _out->print_cr("\n%d classes shared from dynamic cache: %s", closure._aot_dynamics, FileMapInfo::dynamic_info()->full_path());
+    }
   }
 };
 

src/jdk.jcmd/share/man/jcmd.md

@@ -800,16 +800,25 @@ The following commands are available:
     *options*:
 
     -   `-verbose`: (Optional) Dump the detailed content of a Java class.
-        Some classes are annotated with flags: `F` = has, or inherits, a non-empty finalize method,
-        `f` = has final method, `W` = methods rewritten, `C` = marked with `@Contended` annotation,
-        `R` = has been redefined, `S` = is shared class (BOOLEAN, false)
+        Some classes are annotated with flags:
+          - `F` = has, or inherits, a non-empty finalize method,
+          - `f` = has final method,
+          - `W` = methods rewritten,
+          - `C` = marked with `@Contended` annotation,
+          - `R` = has been redefined,
+          - `S` = is shared class (if -location 's' is static and 'd' is dynamic AOT cache location)
+        (BOOLEAN, false)
 
     -   `-location`: (Optional) Print the location of the class file from which the class is loaded (if available)
          If provided by its defining ClassLoader, this option will print a URL specifying the location of the 
-         class file (directory, jar or other URL location) from which this class was loaded.
+         class file (directory, jar or other URL location) from which this class was initially loaded.
 
          Note: JDK (and other classes) loaded by a ClassLoader that does not provide a location URL to the JVM will omit this field.
 
+         Note: if any classes are loaded from an AOT cache, their location reported is that of the original
+               url from which they were loaded at the time of the training run that created the AOT cache.
+
+               The total number of classes loaded from any AOT cache (and its name) are summarized. 
 `VM.classloader_stats`
 :   Print statistics about all ClassLoaders.