diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/oops/fieldInfo.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/oops/fieldInfo.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,257 @@
+/*
+ * Copyright (c) 2011, 2015, 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.
+ *
+ */
+
+#ifndef SHARE_VM_OOPS_FIELDINFO_HPP
+#define SHARE_VM_OOPS_FIELDINFO_HPP
+
+#include "oops/constantPool.hpp"
+#include "oops/typeArrayOop.hpp"
+#include "classfile/vmSymbols.hpp"
+
+// This class represents the field information contained in the fields
+// array of an InstanceKlass.  Currently it's laid on top an array of
+// Java shorts but in the future it could simply be used as a real
+// array type.  FieldInfo generally shouldn't be used directly.
+// Fields should be queried either through InstanceKlass or through
+// the various FieldStreams.
+class FieldInfo VALUE_OBJ_CLASS_SPEC {
+  friend class fieldDescriptor;
+  friend class JavaFieldStream;
+  friend class ClassFileParser;
+
+ public:
+  // fields
+  // Field info extracted from the class file and stored
+  // as an array of 6 shorts.
+
+#define FIELDINFO_TAG_SIZE             2
+#define FIELDINFO_TAG_BLANK            0
+#define FIELDINFO_TAG_OFFSET           1
+#define FIELDINFO_TAG_TYPE_PLAIN       2
+#define FIELDINFO_TAG_TYPE_CONTENDED   3
+#define FIELDINFO_TAG_MASK             3
+
+  // Packed field has the tag, and can be either of:
+  //    hi bits <--------------------------- lo bits
+  //   |---------high---------|---------low---------|
+  //    ..........................................00  - blank
+  //    [------------------offset----------------]01  - real field offset
+  //    ......................[-------type-------]10  - plain field with type
+  //    [--contention_group--][-------type-------]11  - contended field with type and contention group
+  enum FieldOffset {
+    access_flags_offset      = 0,
+    name_index_offset        = 1,
+    signature_index_offset   = 2,
+    initval_index_offset     = 3,
+    low_packed_offset        = 4,
+    high_packed_offset       = 5,
+    field_slots              = 6
+  };
+
+ private:
+  u2 _shorts[field_slots];
+
+  void set_name_index(u2 val)                    { _shorts[name_index_offset] = val;         }
+  void set_signature_index(u2 val)               { _shorts[signature_index_offset] = val;    }
+  void set_initval_index(u2 val)                 { _shorts[initval_index_offset] = val;      }
+
+  u2 name_index() const                          { return _shorts[name_index_offset];        }
+  u2 signature_index() const                     { return _shorts[signature_index_offset];   }
+  u2 initval_index() const                       { return _shorts[initval_index_offset];     }
+
+ public:
+  static FieldInfo* from_field_array(Array<u2>* fields, int index) {
+    return ((FieldInfo*)fields->adr_at(index * field_slots));
+  }
+  static FieldInfo* from_field_array(u2* fields, int index) {
+    return ((FieldInfo*)(fields + index * field_slots));
+  }
+
+  void initialize(u2 access_flags,
+                  u2 name_index,
+                  u2 signature_index,
+                  u2 initval_index) {
+    _shorts[access_flags_offset] = access_flags;
+    _shorts[name_index_offset] = name_index;
+    _shorts[signature_index_offset] = signature_index;
+    _shorts[initval_index_offset] = initval_index;
+    _shorts[low_packed_offset] = 0;
+    _shorts[high_packed_offset] = 0;
+  }
+
+  u2 access_flags() const                        { return _shorts[access_flags_offset];            }
+  u4 offset() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_OFFSET:
+        return build_int_from_shorts(_shorts[low_packed_offset], _shorts[high_packed_offset]) >> FIELDINFO_TAG_SIZE;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        fatal("Asking offset for the plain type field");
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        fatal("Asking offset for the contended type field");
+      case FIELDINFO_TAG_BLANK:
+        fatal("Asking offset for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return 0;
+  }
+
+  bool is_contended() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        return false;
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        return true;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_OFFSET:
+        fatal("Asking contended flag for the field with offset");
+      case FIELDINFO_TAG_BLANK:
+        fatal("Asking contended flag for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return false;
+  }
+
+  u2 contended_group() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        return 0;
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        return _shorts[high_packed_offset];
+#ifndef PRODUCT
+      case FIELDINFO_TAG_OFFSET:
+        fatal("Asking the contended group for the field with offset");
+      case FIELDINFO_TAG_BLANK:
+        fatal("Asking the contended group for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return 0;
+ }
+
+  u2 allocation_type() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        return (lo >> FIELDINFO_TAG_SIZE);
+#ifndef PRODUCT
+      case FIELDINFO_TAG_OFFSET:
+        fatal("Asking the field type for field with offset");
+      case FIELDINFO_TAG_BLANK:
+        fatal("Asking the field type for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return 0;
+  }
+
+  bool is_offset_set() const {
+    return (_shorts[low_packed_offset] & FIELDINFO_TAG_MASK) == FIELDINFO_TAG_OFFSET;
+  }
+
+  Symbol* name(const constantPoolHandle& cp) const {
+    int index = name_index();
+    if (is_internal()) {
+      return lookup_symbol(index);
+    }
+    return cp->symbol_at(index);
+  }
+
+  Symbol* signature(const constantPoolHandle& cp) const {
+    int index = signature_index();
+    if (is_internal()) {
+      return lookup_symbol(index);
+    }
+    return cp->symbol_at(index);
+  }
+
+  void set_access_flags(u2 val)                  { _shorts[access_flags_offset] = val;             }
+  void set_offset(u4 val)                        {
+    val = val << FIELDINFO_TAG_SIZE; // make room for tag
+    _shorts[low_packed_offset] = extract_low_short_from_int(val) | FIELDINFO_TAG_OFFSET;
+    _shorts[high_packed_offset] = extract_high_short_from_int(val);
+  }
+
+  void set_allocation_type(int type) {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_BLANK:
+        _shorts[low_packed_offset] = ((type << FIELDINFO_TAG_SIZE)) & 0xFFFF;
+        _shorts[low_packed_offset] &= ~FIELDINFO_TAG_MASK;
+        _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_PLAIN;
+        return;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_TYPE_PLAIN:
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+      case FIELDINFO_TAG_OFFSET:
+        fatal("Setting the field type with overwriting");
+#endif
+    }
+    ShouldNotReachHere();
+  }
+
+  void set_contended_group(u2 val) {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_CONTENDED;
+        _shorts[high_packed_offset] = val;
+        return;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        fatal("Overwriting contended group");
+      case FIELDINFO_TAG_BLANK:
+        fatal("Setting contended group for the blank field");
+      case FIELDINFO_TAG_OFFSET:
+        fatal("Setting contended group for field with offset");
+#endif
+    }
+    ShouldNotReachHere();
+  }
+
+  bool is_internal() const {
+    return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;
+  }
+
+  bool is_stable() const {
+    return (access_flags() & JVM_ACC_FIELD_STABLE) != 0;
+  }
+  void set_stable(bool z) {
+    if (z) _shorts[access_flags_offset] |=  JVM_ACC_FIELD_STABLE;
+    else   _shorts[access_flags_offset] &= ~JVM_ACC_FIELD_STABLE;
+  }
+
+  Symbol* lookup_symbol(int symbol_index) const {
+    assert(is_internal(), "only internal fields");
+    return vmSymbols::symbol_at((vmSymbols::SID)symbol_index);
+  }
+};
+
+#endif // SHARE_VM_OOPS_FIELDINFO_HPP