8271569: Clean up the use of CDS constants and field offsets

Reviewed-by: iklam, dholmes

src/hotspot/share/cds/cdsConstants.cpp

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2014, 2021, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+
+#include "cds.h"
+#include "cds/cdsConstants.hpp"
+#include "cds/dynamicArchive.hpp"
+#include "cds/filemap.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+CDSConst CDSConstants::offsets[] = {
+  { "CDSFileMapHeaderBase::_magic",           offset_of(CDSFileMapHeaderBase, _magic)           },
+  { "CDSFileMapHeaderBase::_crc",             offset_of(CDSFileMapHeaderBase, _crc)             },
+  { "CDSFileMapHeaderBase::_version",         offset_of(CDSFileMapHeaderBase, _version)         },
+  { "CDSFileMapHeaderBase::_space[0]",        offset_of(CDSFileMapHeaderBase, _space)           },
+  { "FileMapHeader::_jvm_ident",              offset_of(FileMapHeader, _jvm_ident)              },
+  { "FileMapHeader::_base_archive_name_size", offset_of(FileMapHeader, _base_archive_name_size) },
+  { "CDSFileMapRegion::_crc",                 offset_of(CDSFileMapRegion, _crc)                 },
+  { "CDSFileMapRegion::_used",                offset_of(CDSFileMapRegion, _used)                },
+  { "DynamicArchiveHeader::_base_region_crc", offset_of(DynamicArchiveHeader, _base_region_crc) }
+};
+
+CDSConst CDSConstants::constants[] = {
+  { "static_magic",                 (size_t)CDS_ARCHIVE_MAGIC         },
+  { "dynamic_magic",                (size_t)CDS_DYNAMIC_ARCHIVE_MAGIC },
+  { "int_size",                     sizeof(int)                       },
+  { "CDSFileMapRegion_size",        sizeof(CDSFileMapRegion)          },
+  { "static_file_header_size",      sizeof(FileMapHeader)             },
+  { "dynamic_archive_header_size",  sizeof(DynamicArchiveHeader)      },
+  { "size_t_size",                  sizeof(size_t)                    }
+};
+
+size_t CDSConstants::get_cds_offset(const char* name) {
+  for (int i = 0; i < (int)ARRAY_SIZE(offsets); i++) {
+    if (strcmp(name, offsets[i]._name) == 0) {
+        return offsets[i]._value;
+    }
+  }
+  return -1;
+}
+
+size_t CDSConstants::get_cds_constant(const char* name) {
+  for (int i = 0; i < (int)ARRAY_SIZE(constants); i++) {
+    if (strcmp(name, constants[i]._name) == 0) {
+        return constants[i]._value;
+    }
+  }
+  return -1;
+}

src/hotspot/share/cds/cdsoffsets.hpp → src/hotspot/share/cds/cdsConstants.hpp

@@ -22,26 +22,22 @@
  *
  */
 
-#ifndef SHARE_CDS_CDSOFFSETS_HPP
-#define SHARE_CDS_CDSOFFSETS_HPP
+#ifndef SHARE_CDS_CDSCONSTANTS_HPP
+#define SHARE_CDS_CDSCONSTANTS_HPP
 
-#include "memory/allocation.hpp"
+#include "memory/allStatic.hpp"
 
-class CDSOffsets: public CHeapObj<mtInternal> {
+typedef struct {
+  const char* _name;
+  size_t _value;
+} CDSConst;
+
+class CDSConstants : AllStatic {
  private:
-  char* _name;
-  int   _offset;
-  CDSOffsets* _next;
-  static CDSOffsets* _all;  // sole list for cds
+  static CDSConst offsets[];
+  static CDSConst constants[];
  public:
-  CDSOffsets(const char* name, int offset, CDSOffsets* next);
-
-  char* get_name() const { return _name; }
-  int   get_offset() const { return _offset; }
-  CDSOffsets* next() const { return _next; }
-  void add_end(CDSOffsets* n);
-
-  static int find_offset(const char* name);
+  static size_t get_cds_constant(const char* name);
+  static size_t get_cds_offset(const char* name);
 };
-
-#endif // SHARE_CDS_CDSOFFSETS_HPP
+#endif // SHARE_CDS_CDSCONSTANTS_HPP

src/hotspot/share/cds/dynamicArchive.hpp

@@ -38,7 +38,7 @@
 #if INCLUDE_CDS
 
 class DynamicArchiveHeader : public FileMapHeader {
-  friend class CDSOffsets;
+  friend class CDSConstants;
 private:
   int _base_header_crc;
   int _base_region_crc[MetaspaceShared::n_regions];

src/hotspot/share/cds/filemap.hpp

@@ -180,9 +180,10 @@ class FileMapRegion: private CDSFileMapRegion {
 };
 
 class FileMapHeader: private CDSFileMapHeaderBase {
-  friend class CDSOffsets;
+  friend class CDSConstants;
   friend class VMStructs;
 
+private:
   size_t _header_size;
 
   // The following fields record the states of the VM during dump time.
@@ -209,7 +210,6 @@ class FileMapHeader: private CDSFileMapHeaderBase {
   // will function correctly with this JVM and the bootclasspath it's
   // invoked with.
   char  _jvm_ident[JVM_IDENT_MAX];  // identifier string of the jvm that created this dump
-
   // size of the base archive name including NULL terminator
   size_t _base_archive_name_size;
 

src/hotspot/share/include/cds.h

@@ -25,6 +25,8 @@
 #ifndef SHARE_INCLUDE_CDS_H
 #define SHARE_INCLUDE_CDS_H
 
+#include <stddef.h>
+
 // This file declares the CDS data structures that are used by the HotSpot Serviceability Agent
 // (see C sources inside src/jdk.hotspot.agent).
 //

src/hotspot/share/prims/whitebox.cpp

@@ -24,7 +24,7 @@
 
 #include "precompiled.hpp"
 #include <new>
-#include "cds/cdsoffsets.hpp"
+#include "cds/cdsConstants.hpp"
 #include "cds/filemap.hpp"
 #include "cds/heapShared.inline.hpp"
 #include "cds/metaspaceShared.hpp"
@@ -2016,11 +2016,18 @@ WB_END
 
 #if INCLUDE_CDS
 
-WB_ENTRY(jint, WB_GetOffsetForName(JNIEnv* env, jobject o, jstring name))
+WB_ENTRY(jint, WB_GetCDSOffsetForName(JNIEnv* env, jobject o, jstring name))
   ResourceMark rm;
   char* c_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
-  int result = CDSOffsets::find_offset(c_name);
-  return (jint)result;
+  jint result = (jint)CDSConstants::get_cds_offset(c_name);
+  return result;
+WB_END
+
+WB_ENTRY(jint, WB_GetCDSConstantForName(JNIEnv* env, jobject o, jstring name))
+  ResourceMark rm;
+  char* c_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
+  jint result = (jint)CDSConstants::get_cds_constant(c_name);
+  return result;
 WB_END
 
 #endif // INCLUDE_CDS
@@ -2454,7 +2461,8 @@ static JNINativeMethod methods[] = {
   {CC"readFromNoaccessArea",CC"()V",                  (void*)&WB_ReadFromNoaccessArea},
   {CC"stressVirtualSpaceResize",CC"(JJJ)I",           (void*)&WB_StressVirtualSpaceResize},
 #if INCLUDE_CDS
-  {CC"getOffsetForName0", CC"(Ljava/lang/String;)I",  (void*)&WB_GetOffsetForName},
+  {CC"getCDSOffsetForName0", CC"(Ljava/lang/String;)I",  (void*)&WB_GetCDSOffsetForName},
+  {CC"getCDSConstantForName0", CC"(Ljava/lang/String;)I",  (void*)&WB_GetCDSConstantForName},
 #endif
 #if INCLUDE_G1GC
   {CC"g1InConcurrentMark", CC"()Z",                   (void*)&WB_G1InConcurrentMark},