6964458: Reimplement class meta-data storage to use native memory

Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes

Co-authored-by: Stefan Karlsson <stefan.karlsson@oracle.com>
Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Co-authored-by: Tom Rodriguez <tom.rodriguez@oracle.com>
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland

hotspot/src/share/vm/oops/constantPool.hpp

@@ -0,0 +1,928 @@
+/*
+ * Copyright (c) 1997, 2012, 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_CONSTANTPOOLOOP_HPP
+#define SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP
+
+#include "oops/arrayOop.hpp"
+#include "oops/cpCache.hpp"
+#include "oops/objArrayOop.hpp"
+#include "oops/symbol.hpp"
+#include "oops/typeArrayOop.hpp"
+#include "runtime/handles.hpp"
+#include "utilities/constantTag.hpp"
+#ifdef TARGET_ARCH_x86
+# include "bytes_x86.hpp"
+#endif
+#ifdef TARGET_ARCH_sparc
+# include "bytes_sparc.hpp"
+#endif
+#ifdef TARGET_ARCH_zero
+# include "bytes_zero.hpp"
+#endif
+#ifdef TARGET_ARCH_arm
+# include "bytes_arm.hpp"
+#endif
+#ifdef TARGET_ARCH_ppc
+# include "bytes_ppc.hpp"
+#endif
+
+// A constantPool is an array containing class constants as described in the
+// class file.
+//
+// Most of the constant pool entries are written during class parsing, which
+// is safe.  For klass types, the constant pool entry is
+// modified when the entry is resolved.  If a klass constant pool
+// entry is read without a lock, only the resolved state guarantees that
+// the entry in the constant pool is a klass object and not a Symbol*.
+
+class SymbolHashMap;
+
+class CPSlot VALUE_OBJ_CLASS_SPEC {
+  intptr_t _ptr;
+ public:
+  CPSlot(intptr_t ptr): _ptr(ptr) {}
+  CPSlot(Klass* ptr): _ptr((intptr_t)ptr) {}
+  CPSlot(Symbol* ptr): _ptr((intptr_t)ptr | 1) {}
+
+  intptr_t value()   { return _ptr; }
+  bool is_resolved()   { return (_ptr & 1) == 0; }
+  bool is_unresolved() { return (_ptr & 1) == 1; }
+
+  Symbol* get_symbol() {
+    assert(is_unresolved(), "bad call");
+    return (Symbol*)(_ptr & ~1);
+  }
+  Klass* get_klass() {
+    assert(is_resolved(), "bad call");
+    return (Klass*)_ptr;
+  }
+};
+
+class ConstantPool : public Metadata {
+  friend class VMStructs;
+  friend class BytecodeInterpreter;  // Directly extracts an oop in the pool for fast instanceof/checkcast
+  friend class Universe;             // For null constructor
+ private:
+  Array<u1>*           _tags;        // the tag array describing the constant pool's contents
+  ConstantPoolCache* _cache;       // the cache holding interpreter runtime information
+  Klass*               _pool_holder; // the corresponding class
+  Array<u2>*           _operands;    // for variable-sized (InvokeDynamic) nodes, usually empty
+
+  // Array of resolved objects from the constant pool and map from resolved
+  // object index to original constant pool index
+  jobject              _resolved_references;
+  Array<u2>*           _reference_map;
+
+  int                  _flags;         // a few header bits to describe contents for GC
+  int                  _length; // number of elements in the array
+
+  bool                 _on_stack;     // Redefined method still executing refers to this constant pool.
+
+  union {
+    // set for CDS to restore resolved references
+    int                _resolved_reference_length;
+  // only set to non-zero if constant pool is merged by RedefineClasses
+  int                  _orig_length;
+  } _saved;
+
+  Monitor*             _lock;
+
+  void set_tags(Array<u1>* tags)               { _tags = tags; }
+  void tag_at_put(int which, jbyte t)          { tags()->at_put(which, t); }
+  void release_tag_at_put(int which, jbyte t)  { tags()->release_at_put(which, t); }
+
+  void set_operands(Array<u2>* operands)       { _operands = operands; }
+
+  enum FlagBit {
+    FB_has_invokedynamic = 1,
+    FB_has_pseudo_string = 2,
+    FB_has_preresolution = 3
+  };
+
+  int flags() const                         { return _flags; }
+  void set_flags(int f)                     { _flags = f; }
+  bool flag_at(FlagBit fb) const            { return (_flags & (1 << (int)fb)) != 0; }
+  void set_flag_at(FlagBit fb);
+  // no clear_flag_at function; they only increase
+
+ private:
+  intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(ConstantPool)); }
+
+  CPSlot slot_at(int which) {
+    assert(is_within_bounds(which), "index out of bounds");
+    // Uses volatile because the klass slot changes without a lock.
+    volatile intptr_t adr = (intptr_t)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which));
+    assert(adr != 0 || which == 0, "cp entry for klass should not be zero");
+    return CPSlot(adr);
+  }
+
+  void slot_at_put(int which, CPSlot s) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    assert(s.value() != 0, "Caught something");
+    *(intptr_t*)&base()[which] = s.value();
+  }
+  intptr_t* obj_at_addr_raw(int which) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    return (intptr_t*) &base()[which];
+  }
+
+  jint* int_at_addr(int which) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    return (jint*) &base()[which];
+  }
+
+  jlong* long_at_addr(int which) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    return (jlong*) &base()[which];
+  }
+
+  jfloat* float_at_addr(int which) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    return (jfloat*) &base()[which];
+  }
+
+  jdouble* double_at_addr(int which) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    return (jdouble*) &base()[which];
+  }
+
+  ConstantPool(Array<u1>* tags);
+  ConstantPool() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
+ public:
+  static ConstantPool* allocate(ClassLoaderData* loader_data, int length, TRAPS);
+
+  bool is_constantPool() const volatile     { return true; }
+
+  Array<u1>* tags() const                   { return _tags; }
+  Array<u2>* operands() const               { return _operands; }
+
+  bool has_pseudo_string() const            { return flag_at(FB_has_pseudo_string); }
+  bool has_invokedynamic() const            { return flag_at(FB_has_invokedynamic); }
+  bool has_preresolution() const            { return flag_at(FB_has_preresolution); }
+  void set_pseudo_string()                  {    set_flag_at(FB_has_pseudo_string); }
+  void set_invokedynamic()                  {    set_flag_at(FB_has_invokedynamic); }
+  void set_preresolution()                  {    set_flag_at(FB_has_preresolution); }
+
+  // Redefine classes support.  If a method refering to this constant pool
+  // is on the executing stack, or as a handle in vm code, this constant pool
+  // can't be removed from the set of previous versions saved in the instance
+  // class.
+  bool on_stack() const                     { return _on_stack; }
+  void set_on_stack(const bool value);
+
+  // Klass holding pool
+  Klass* pool_holder() const              { return _pool_holder; }
+  void set_pool_holder(Klass* k)          { _pool_holder = k; }
+  Klass** pool_holder_addr()              { return &_pool_holder; }
+
+  // Interpreter runtime support
+  ConstantPoolCache* cache() const        { return _cache; }
+  void set_cache(ConstantPoolCache* cache){ _cache = cache; }
+
+  // Create object cache in the constant pool
+  void initialize_resolved_references(ClassLoaderData* loader_data,
+                                      intStack reference_map,
+                                      int constant_pool_map_length,
+                                      TRAPS);
+
+  // resolved strings, methodHandles and callsite objects from the constant pool
+  objArrayOop resolved_references()  const;
+  // mapping resolved object array indexes to cp indexes and back.
+  int object_to_cp_index(int index)         { return _reference_map->at(index); }
+  int cp_to_object_index(int index);
+
+  // Invokedynamic indexes.
+  // They must look completely different from normal indexes.
+  // The main reason is that byte swapping is sometimes done on normal indexes.
+  // Finally, it is helpful for debugging to tell the two apart.
+  static bool is_invokedynamic_index(int i) { return (i < 0); }
+  static int  decode_invokedynamic_index(int i) { assert(is_invokedynamic_index(i),  ""); return ~i; }
+  static int  encode_invokedynamic_index(int i) { assert(!is_invokedynamic_index(i), ""); return ~i; }
+
+
+  // The invokedynamic points at a CP cache entry.  This entry points back
+  // at the original CP entry (CONSTANT_InvokeDynamic) and also (via f2) at an entry
+  // in the resolved_references array (which provides the appendix argument).
+  int invokedynamic_cp_cache_index(int index) const {
+    assert (is_invokedynamic_index(index), "should be a invokedynamic index");
+    int cache_index = decode_invokedynamic_index(index);
+    return cache_index;
+  }
+  ConstantPoolCacheEntry* invokedynamic_cp_cache_entry_at(int index) const {
+    // decode index that invokedynamic points to.
+    int cp_cache_index = invokedynamic_cp_cache_index(index);
+    return cache()->entry_at(cp_cache_index);
+  }
+
+  // Assembly code support
+  static int tags_offset_in_bytes()         { return offset_of(ConstantPool, _tags); }
+  static int cache_offset_in_bytes()        { return offset_of(ConstantPool, _cache); }
+  static int pool_holder_offset_in_bytes()  { return offset_of(ConstantPool, _pool_holder); }
+  static int resolved_references_offset_in_bytes() { return offset_of(ConstantPool, _resolved_references); }
+  static int reference_map_offset_in_bytes() { return offset_of(ConstantPool, _reference_map); }
+
+  // Storing constants
+
+  void klass_at_put(int which, Klass* k) {
+    assert(k != NULL, "resolved class shouldn't be null");
+    assert(is_within_bounds(which), "index out of bounds");
+    OrderAccess::release_store_ptr((Klass* volatile *)obj_at_addr_raw(which), k);
+    // The interpreter assumes when the tag is stored, the klass is resolved
+    // and the Klass* is a klass rather than a Symbol*, so we need
+    // hardware store ordering here.
+    release_tag_at_put(which, JVM_CONSTANT_Class);
+  }
+
+  // For temporary use while constructing constant pool
+  void klass_index_at_put(int which, int name_index) {
+    tag_at_put(which, JVM_CONSTANT_ClassIndex);
+    *int_at_addr(which) = name_index;
+  }
+
+  // Temporary until actual use
+  void unresolved_klass_at_put(int which, Symbol* s) {
+    release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);
+    slot_at_put(which, s);
+  }
+
+  void method_handle_index_at_put(int which, int ref_kind, int ref_index) {
+    tag_at_put(which, JVM_CONSTANT_MethodHandle);
+    *int_at_addr(which) = ((jint) ref_index<<16) | ref_kind;
+  }
+
+  void method_type_index_at_put(int which, int ref_index) {
+    tag_at_put(which, JVM_CONSTANT_MethodType);
+    *int_at_addr(which) = ref_index;
+  }
+
+  void invoke_dynamic_at_put(int which, int bootstrap_specifier_index, int name_and_type_index) {
+    tag_at_put(which, JVM_CONSTANT_InvokeDynamic);
+    *int_at_addr(which) = ((jint) name_and_type_index<<16) | bootstrap_specifier_index;
+  }
+
+  void unresolved_string_at_put(int which, Symbol* s) {
+    release_tag_at_put(which, JVM_CONSTANT_String);
+    *symbol_at_addr(which) = s;
+  }
+
+  void int_at_put(int which, jint i) {
+    tag_at_put(which, JVM_CONSTANT_Integer);
+    *int_at_addr(which) = i;
+  }
+
+  void long_at_put(int which, jlong l) {
+    tag_at_put(which, JVM_CONSTANT_Long);
+    // *long_at_addr(which) = l;
+    Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));
+  }
+
+  void float_at_put(int which, jfloat f) {
+    tag_at_put(which, JVM_CONSTANT_Float);
+    *float_at_addr(which) = f;
+  }
+
+  void double_at_put(int which, jdouble d) {
+    tag_at_put(which, JVM_CONSTANT_Double);
+    // *double_at_addr(which) = d;
+    // u8 temp = *(u8*) &d;
+    Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));
+  }
+
+  Symbol** symbol_at_addr(int which) const {
+    assert(is_within_bounds(which), "index out of bounds");
+    return (Symbol**) &base()[which];
+  }
+
+  void symbol_at_put(int which, Symbol* s) {
+    assert(s->refcount() != 0, "should have nonzero refcount");
+    tag_at_put(which, JVM_CONSTANT_Utf8);
+    *symbol_at_addr(which) = s;
+  }
+
+  void string_at_put(int which, int obj_index, oop str) {
+    resolved_references()->obj_at_put(obj_index, str);
+  }
+
+  void set_object_tag_at(int which) {
+    release_tag_at_put(which, JVM_CONSTANT_Object);
+    }
+
+  void object_at_put(int which, oop obj) {
+    resolved_references()->obj_at_put(cp_to_object_index(which), obj);
+  }
+
+  // For temporary use while constructing constant pool
+  void string_index_at_put(int which, int string_index) {
+    tag_at_put(which, JVM_CONSTANT_StringIndex);
+    *int_at_addr(which) = string_index;
+  }
+
+  void field_at_put(int which, int class_index, int name_and_type_index) {
+    tag_at_put(which, JVM_CONSTANT_Fieldref);
+    *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
+  }
+
+  void method_at_put(int which, int class_index, int name_and_type_index) {
+    tag_at_put(which, JVM_CONSTANT_Methodref);
+    *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
+  }
+
+  void interface_method_at_put(int which, int class_index, int name_and_type_index) {
+    tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);
+    *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;  // Not so nice
+  }
+
+  void name_and_type_at_put(int which, int name_index, int signature_index) {
+    tag_at_put(which, JVM_CONSTANT_NameAndType);
+    *int_at_addr(which) = ((jint) signature_index<<16) | name_index;  // Not so nice
+  }
+
+  // Tag query
+
+  constantTag tag_at(int which) const { return (constantTag)tags()->at_acquire(which); }
+
+  // Fetching constants
+
+  Klass* klass_at(int which, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    return klass_at_impl(h_this, which, CHECK_NULL);
+  }
+
+  Symbol* klass_name_at(int which);  // Returns the name, w/o resolving.
+
+  Klass* resolved_klass_at(int which) {  // Used by Compiler
+    guarantee(tag_at(which).is_klass(), "Corrupted constant pool");
+    // Must do an acquire here in case another thread resolved the klass
+    // behind our back, lest we later load stale values thru the oop.
+    return CPSlot((Klass*)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which))).get_klass();
+  }
+
+  // This method should only be used with a cpool lock or during parsing or gc
+  Symbol* unresolved_klass_at(int which) {     // Temporary until actual use
+    Symbol* s = CPSlot((Symbol*)OrderAccess::load_ptr_acquire(obj_at_addr_raw(which))).get_symbol();
+    // check that the klass is still unresolved.
+    assert(tag_at(which).is_unresolved_klass(), "Corrupted constant pool");
+    return s;
+  }
+
+  // RedefineClasses() API support:
+  Symbol* klass_at_noresolve(int which) { return klass_name_at(which); }
+
+  jint int_at(int which) {
+    assert(tag_at(which).is_int(), "Corrupted constant pool");
+    return *int_at_addr(which);
+  }
+
+  jlong long_at(int which) {
+    assert(tag_at(which).is_long(), "Corrupted constant pool");
+    // return *long_at_addr(which);
+    u8 tmp = Bytes::get_native_u8((address)&base()[which]);
+    return *((jlong*)&tmp);
+  }
+
+  jfloat float_at(int which) {
+    assert(tag_at(which).is_float(), "Corrupted constant pool");
+    return *float_at_addr(which);
+  }
+
+  jdouble double_at(int which) {
+    assert(tag_at(which).is_double(), "Corrupted constant pool");
+    u8 tmp = Bytes::get_native_u8((address)&base()[which]);
+    return *((jdouble*)&tmp);
+  }
+
+  Symbol* symbol_at(int which) {
+    assert(tag_at(which).is_utf8(), "Corrupted constant pool");
+    return *symbol_at_addr(which);
+  }
+
+  oop string_at(int which, int obj_index, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    return string_at_impl(h_this, which, obj_index, THREAD);
+  }
+  oop string_at(int which, TRAPS) {
+    int obj_index = cp_to_object_index(which);
+    return string_at(which, obj_index, THREAD);
+  }
+
+  // Version that can be used before string oop array is created.
+  oop uncached_string_at(int which, TRAPS);
+
+  oop object_at(int which) {
+    assert(tag_at(which).is_object(), "Corrupted constant pool");
+    int obj_index = cp_to_object_index(which);
+    return resolved_references()->obj_at(obj_index);
+  }
+
+  // A "pseudo-string" is an non-string oop that has found is way into
+  // a String entry.
+  // Under EnableInvokeDynamic this can happen if the user patches a live
+  // object into a CONSTANT_String entry of an anonymous class.
+  // Method oops internally created for method handles may also
+  // use pseudo-strings to link themselves to related metaobjects.
+
+  bool is_pseudo_string_at(int which) {
+    // A pseudo string is a string that doesn't have a symbol in the cpSlot
+    return unresolved_string_at(which) == NULL;
+  }
+
+  oop pseudo_string_at(int which, int obj_index) {
+    assert(tag_at(which).is_string(), "Corrupted constant pool");
+    assert(unresolved_string_at(which) == NULL, "shouldn't have symbol");
+    oop s = resolved_references()->obj_at(obj_index);
+    return s;
+  }
+
+  void pseudo_string_at_put(int which, int obj_index, oop x) {
+    assert(EnableInvokeDynamic, "");
+    set_pseudo_string();        // mark header
+    assert(tag_at(which).is_string(), "Corrupted constant pool");
+    string_at_put(which, obj_index, x);    // this works just fine
+  }
+
+  // only called when we are sure a string entry is already resolved (via an
+  // earlier string_at call.
+  oop resolved_string_at(int which) {
+    assert(tag_at(which).is_string(), "Corrupted constant pool");
+    // Must do an acquire here in case another thread resolved the klass
+    // behind our back, lest we later load stale values thru the oop.
+    // we might want a volatile_obj_at in objArrayKlass.
+    int obj_index = cp_to_object_index(which);
+    return resolved_references()->obj_at(obj_index);
+  }
+
+  Symbol* unresolved_string_at(int which) {
+    assert(tag_at(which).is_string(), "Corrupted constant pool");
+    Symbol* s = *symbol_at_addr(which);
+    return s;
+  }
+
+  // Returns an UTF8 for a CONSTANT_String entry at a given index.
+  // UTF8 char* representation was chosen to avoid conversion of
+  // java_lang_Strings at resolved entries into Symbol*s
+  // or vice versa.
+  // Caller is responsible for checking for pseudo-strings.
+  char* string_at_noresolve(int which);
+
+  jint name_and_type_at(int which) {
+    assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
+    return *int_at_addr(which);
+  }
+
+  int method_handle_ref_kind_at(int which) {
+    assert(tag_at(which).is_method_handle(), "Corrupted constant pool");
+    return extract_low_short_from_int(*int_at_addr(which));  // mask out unwanted ref_index bits
+  }
+  int method_handle_index_at(int which) {
+    assert(tag_at(which).is_method_handle(), "Corrupted constant pool");
+    return extract_high_short_from_int(*int_at_addr(which));  // shift out unwanted ref_kind bits
+  }
+  int method_type_index_at(int which) {
+    assert(tag_at(which).is_method_type(), "Corrupted constant pool");
+    return *int_at_addr(which);
+  }
+  // Derived queries:
+  Symbol* method_handle_name_ref_at(int which) {
+    int member = method_handle_index_at(which);
+    return impl_name_ref_at(member, true);
+  }
+  Symbol* method_handle_signature_ref_at(int which) {
+    int member = method_handle_index_at(which);
+    return impl_signature_ref_at(member, true);
+  }
+  int method_handle_klass_index_at(int which) {
+    int member = method_handle_index_at(which);
+    return impl_klass_ref_index_at(member, true);
+  }
+  Symbol* method_type_signature_at(int which) {
+    int sym = method_type_index_at(which);
+    return symbol_at(sym);
+  }
+
+  int invoke_dynamic_name_and_type_ref_index_at(int which) {
+    assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
+    return extract_high_short_from_int(*int_at_addr(which));
+  }
+  int invoke_dynamic_bootstrap_specifier_index(int which) {
+    assert(tag_at(which).value() == JVM_CONSTANT_InvokeDynamic, "Corrupted constant pool");
+    return extract_low_short_from_int(*int_at_addr(which));
+  }
+  int invoke_dynamic_operand_base(int which) {
+    int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
+    return operand_offset_at(operands(), bootstrap_specifier_index);
+  }
+  // The first part of the operands array consists of an index into the second part.
+  // Extract a 32-bit index value from the first part.
+  static int operand_offset_at(Array<u2>* operands, int bootstrap_specifier_index) {
+    int n = (bootstrap_specifier_index * 2);
+    assert(n >= 0 && n+2 <= operands->length(), "oob");
+    // The first 32-bit index points to the beginning of the second part
+    // of the operands array.  Make sure this index is in the first part.
+    DEBUG_ONLY(int second_part = build_int_from_shorts(operands->at(0),
+                                                       operands->at(1)));
+    assert(second_part == 0 || n+2 <= second_part, "oob (2)");
+    int offset = build_int_from_shorts(operands->at(n+0),
+                                       operands->at(n+1));
+    // The offset itself must point into the second part of the array.
+    assert(offset == 0 || offset >= second_part && offset <= operands->length(), "oob (3)");
+    return offset;
+  }
+  static void operand_offset_at_put(Array<u2>* operands, int bootstrap_specifier_index, int offset) {
+    int n = bootstrap_specifier_index * 2;
+    assert(n >= 0 && n+2 <= operands->length(), "oob");
+    operands->at_put(n+0, extract_low_short_from_int(offset));
+    operands->at_put(n+1, extract_high_short_from_int(offset));
+  }
+  static int operand_array_length(Array<u2>* operands) {
+    if (operands == NULL || operands->length() == 0)  return 0;
+    int second_part = operand_offset_at(operands, 0);
+    return (second_part / 2);
+  }
+
+#ifdef ASSERT
+  // operand tuples fit together exactly, end to end
+  static int operand_limit_at(Array<u2>* operands, int bootstrap_specifier_index) {
+    int nextidx = bootstrap_specifier_index + 1;
+    if (nextidx == operand_array_length(operands))
+      return operands->length();
+    else
+      return operand_offset_at(operands, nextidx);
+  }
+  int invoke_dynamic_operand_limit(int which) {
+    int bootstrap_specifier_index = invoke_dynamic_bootstrap_specifier_index(which);
+    return operand_limit_at(operands(), bootstrap_specifier_index);
+  }
+#endif //ASSERT
+
+  // layout of InvokeDynamic bootstrap method specifier (in second part of operands array):
+  enum {
+         _indy_bsm_offset  = 0,  // CONSTANT_MethodHandle bsm
+         _indy_argc_offset = 1,  // u2 argc
+         _indy_argv_offset = 2   // u2 argv[argc]
+  };
+  int invoke_dynamic_bootstrap_method_ref_index_at(int which) {
+    assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
+    int op_base = invoke_dynamic_operand_base(which);
+    return operands()->at(op_base + _indy_bsm_offset);
+  }
+  int invoke_dynamic_argument_count_at(int which) {
+    assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
+    int op_base = invoke_dynamic_operand_base(which);
+    int argc = operands()->at(op_base + _indy_argc_offset);
+    DEBUG_ONLY(int end_offset = op_base + _indy_argv_offset + argc;
+               int next_offset = invoke_dynamic_operand_limit(which));
+    assert(end_offset == next_offset, "matched ending");
+    return argc;
+  }
+  int invoke_dynamic_argument_index_at(int which, int j) {
+    int op_base = invoke_dynamic_operand_base(which);
+    DEBUG_ONLY(int argc = operands()->at(op_base + _indy_argc_offset));
+    assert((uint)j < (uint)argc, "oob");
+    return operands()->at(op_base + _indy_argv_offset + j);
+  }
+
+  // The following methods (name/signature/klass_ref_at, klass_ref_at_noresolve,
+  // name_and_type_ref_index_at) all expect to be passed indices obtained
+  // directly from the bytecode.
+  // If the indices are meant to refer to fields or methods, they are
+  // actually rewritten constant pool cache indices.
+  // The routine remap_instruction_operand_from_cache manages the adjustment
+  // of these values back to constant pool indices.
+
+  // There are also "uncached" versions which do not adjust the operand index; see below.
+
+  // FIXME: Consider renaming these with a prefix "cached_" to make the distinction clear.
+  // In a few cases (the verifier) there are uses before a cpcache has been built,
+  // which are handled by a dynamic check in remap_instruction_operand_from_cache.
+  // FIXME: Remove the dynamic check, and adjust all callers to specify the correct mode.
+
+  // Lookup for entries consisting of (klass_index, name_and_type index)
+  Klass* klass_ref_at(int which, TRAPS);
+  Symbol* klass_ref_at_noresolve(int which);
+  Symbol* name_ref_at(int which)                { return impl_name_ref_at(which, false); }
+  Symbol* signature_ref_at(int which)           { return impl_signature_ref_at(which, false); }
+
+  int klass_ref_index_at(int which)               { return impl_klass_ref_index_at(which, false); }
+  int name_and_type_ref_index_at(int which)       { return impl_name_and_type_ref_index_at(which, false); }
+
+  // Lookup for entries consisting of (name_index, signature_index)
+  int name_ref_index_at(int which_nt);            // ==  low-order jshort of name_and_type_at(which_nt)
+  int signature_ref_index_at(int which_nt);       // == high-order jshort of name_and_type_at(which_nt)
+
+  BasicType basic_type_for_signature_at(int which);
+
+  // Resolve string constants (to prevent allocation during compilation)
+  void resolve_string_constants(TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    resolve_string_constants_impl(h_this, CHECK);
+  }
+
+  // CDS support
+  void remove_unshareable_info();
+  void restore_unshareable_info(TRAPS);
+  bool resolve_class_constants(TRAPS);
+
+ private:
+  enum { _no_index_sentinel = -1, _possible_index_sentinel = -2 };
+ public:
+
+  // Resolve late bound constants.
+  oop resolve_constant_at(int index, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    return resolve_constant_at_impl(h_this, index, _no_index_sentinel, THREAD);
+  }
+
+  oop resolve_cached_constant_at(int cache_index, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    return resolve_constant_at_impl(h_this, _no_index_sentinel, cache_index, THREAD);
+  }
+
+  oop resolve_possibly_cached_constant_at(int pool_index, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    return resolve_constant_at_impl(h_this, pool_index, _possible_index_sentinel, THREAD);
+  }
+
+  oop resolve_bootstrap_specifier_at(int index, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    return resolve_bootstrap_specifier_at_impl(h_this, index, THREAD);
+  }
+
+  // Klass name matches name at offset
+  bool klass_name_at_matches(instanceKlassHandle k, int which);
+
+  // Sizing
+  int length() const                   { return _length; }
+  void set_length(int length)          { _length = length; }
+
+  // Tells whether index is within bounds.
+  bool is_within_bounds(int index) const {
+    return 0 <= index && index < length();
+  }
+
+  static int header_size()             { return sizeof(ConstantPool)/HeapWordSize; }
+  static int size(int length)          { return align_object_size(header_size() + length); }
+  int size() const                     { return size(length()); }
+
+  friend class ClassFileParser;
+  friend class SystemDictionary;
+
+  // Used by compiler to prevent classloading.
+  static Method*         method_at_if_loaded      (constantPoolHandle this_oop, int which);
+  static bool      has_appendix_at_if_loaded      (constantPoolHandle this_oop, int which);
+  static oop           appendix_at_if_loaded      (constantPoolHandle this_oop, int which);
+  static Klass*           klass_at_if_loaded      (constantPoolHandle this_oop, int which);
+  static Klass*       klass_ref_at_if_loaded      (constantPoolHandle this_oop, int which);
+  // Same as above - but does LinkResolving.
+  static Klass*       klass_ref_at_if_loaded_check(constantPoolHandle this_oop, int which, TRAPS);
+
+  // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
+  // future by other Java code. These take constant pool indices rather than
+  // constant pool cache indices as do the peer methods above.
+  Symbol* uncached_klass_ref_at_noresolve(int which);
+  Symbol* uncached_name_ref_at(int which)                 { return impl_name_ref_at(which, true); }
+  Symbol* uncached_signature_ref_at(int which)            { return impl_signature_ref_at(which, true); }
+  int       uncached_klass_ref_index_at(int which)          { return impl_klass_ref_index_at(which, true); }
+  int       uncached_name_and_type_ref_index_at(int which)  { return impl_name_and_type_ref_index_at(which, true); }
+
+  // Sharing
+  int pre_resolve_shared_klasses(TRAPS);
+
+  // Debugging
+  const char* printable_name_at(int which) PRODUCT_RETURN0;
+
+#ifdef ASSERT
+  enum { CPCACHE_INDEX_TAG = 0x10000 };  // helps keep CP cache indices distinct from CP indices
+#else
+  enum { CPCACHE_INDEX_TAG = 0 };        // in product mode, this zero value is a no-op
+#endif //ASSERT
+
+  static int decode_cpcache_index(int raw_index, bool invokedynamic_ok = false) {
+    if (invokedynamic_ok && is_invokedynamic_index(raw_index))
+      return decode_invokedynamic_index(raw_index);
+    else
+      return raw_index - CPCACHE_INDEX_TAG;
+  }
+
+ private:
+
+  void set_resolved_references(jobject s) { _resolved_references = s; }
+  Array<u2>* reference_map() const        { return _reference_map; }
+  void set_reference_map(Array<u2>* o)    { _reference_map = o; }
+
+  // patch JSR 292 resolved references after the class is linked.
+  void patch_resolved_references(GrowableArray<Handle>* cp_patches);
+
+  Symbol* impl_name_ref_at(int which, bool uncached);
+  Symbol* impl_signature_ref_at(int which, bool uncached);
+  int       impl_klass_ref_index_at(int which, bool uncached);
+  int       impl_name_and_type_ref_index_at(int which, bool uncached);
+
+  int remap_instruction_operand_from_cache(int operand);  // operand must be biased by CPCACHE_INDEX_TAG
+
+  // Used while constructing constant pool (only by ClassFileParser)
+  jint klass_index_at(int which) {
+    assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
+    return *int_at_addr(which);
+  }
+
+  jint string_index_at(int which) {
+    assert(tag_at(which).is_string_index(), "Corrupted constant pool");
+    return *int_at_addr(which);
+  }
+
+  // Performs the LinkResolver checks
+  static void verify_constant_pool_resolve(constantPoolHandle this_oop, KlassHandle klass, TRAPS);
+
+  // Implementation of methods that needs an exposed 'this' pointer, in order to
+  // handle GC while executing the method
+  static Klass* klass_at_impl(constantPoolHandle this_oop, int which, TRAPS);
+  static oop string_at_impl(constantPoolHandle this_oop, int which, int obj_index, TRAPS);
+
+  // Resolve string constants (to prevent allocation during compilation)
+  static void resolve_string_constants_impl(constantPoolHandle this_oop, TRAPS);
+
+  static oop resolve_constant_at_impl(constantPoolHandle this_oop, int index, int cache_index, TRAPS);
+  static void save_and_throw_exception(constantPoolHandle this_oop, int which, int tag_value, TRAPS);
+  static oop resolve_bootstrap_specifier_at_impl(constantPoolHandle this_oop, int index, TRAPS);
+
+ public:
+  // Merging ConstantPool* support:
+  bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);
+  void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i, TRAPS) {
+    constantPoolHandle h_this(THREAD, this);
+    copy_cp_to_impl(h_this, start_i, end_i, to_cp, to_i, THREAD);
+  }
+  static void copy_cp_to_impl(constantPoolHandle from_cp, int start_i, int end_i, constantPoolHandle to_cp, int to_i, TRAPS);
+  static void copy_entry_to(constantPoolHandle from_cp, int from_i, constantPoolHandle to_cp, int to_i, TRAPS);
+  int  find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);
+  int  orig_length() const                { return _saved._orig_length; }
+  void set_orig_length(int orig_length)   { _saved._orig_length = orig_length; }
+
+  void set_resolved_reference_length(int length) { _saved._resolved_reference_length = length; }
+  int  resolved_reference_length() const  { return _saved._resolved_reference_length; }
+  void set_lock(Monitor* lock)            { _lock = lock; }
+  Monitor* lock()                         { return _lock; }
+
+  // Decrease ref counts of symbols that are in the constant pool
+  // when the holder class is unloaded
+  void unreference_symbols();
+
+  // Deallocate constant pool for RedefineClasses
+  void deallocate_contents(ClassLoaderData* loader_data);
+  void release_C_heap_structures();
+
+  // JVMTI accesss - GetConstantPool, RetransformClasses, ...
+  friend class JvmtiConstantPoolReconstituter;
+
+ private:
+  jint cpool_entry_size(jint idx);
+  jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
+
+  // Copy cpool bytes into byte array.
+  // Returns:
+  //  int > 0, count of the raw cpool bytes that have been copied
+  //        0, OutOfMemory error
+  //       -1, Internal error
+  int  copy_cpool_bytes(int cpool_size,
+                        SymbolHashMap* tbl,
+                        unsigned char *bytes);
+
+ public:
+  // Verify
+  void verify_on(outputStream* st);
+
+  // Printing
+  void print_on(outputStream* st) const;
+  void print_value_on(outputStream* st) const;
+  void print_entry_on(int index, outputStream* st);
+
+  const char* internal_name() const { return "{constant pool}"; }
+
+#ifndef PRODUCT
+  // Compile the world support
+  static void preload_and_initialize_all_classes(ConstantPool* constant_pool, TRAPS);
+#endif
+};
+
+class SymbolHashMapEntry : public CHeapObj<mtSymbol> {
+ private:
+  unsigned int        _hash;   // 32-bit hash for item
+  SymbolHashMapEntry* _next;   // Next element in the linked list for this bucket
+  Symbol*             _symbol; // 1-st part of the mapping: symbol => value
+  u2                  _value;  // 2-nd part of the mapping: symbol => value
+
+ public:
+  unsigned   int hash() const             { return _hash;   }
+  void       set_hash(unsigned int hash)  { _hash = hash;   }
+
+  SymbolHashMapEntry* next() const        { return _next;   }
+  void set_next(SymbolHashMapEntry* next) { _next = next;   }
+
+  Symbol*    symbol() const               { return _symbol; }
+  void       set_symbol(Symbol* sym)      { _symbol = sym;  }
+
+  u2         value() const                {  return _value; }
+  void       set_value(u2 value)          { _value = value; }
+
+  SymbolHashMapEntry(unsigned int hash, Symbol* symbol, u2 value)
+    : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
+
+}; // End SymbolHashMapEntry class
+
+
+class SymbolHashMapBucket : public CHeapObj<mtSymbol> {
+
+private:
+  SymbolHashMapEntry*    _entry;
+
+public:
+  SymbolHashMapEntry* entry() const         {  return _entry; }
+  void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
+  void clear()                              { _entry = NULL;  }
+
+}; // End SymbolHashMapBucket class
+
+
+class SymbolHashMap: public CHeapObj<mtSymbol> {
+
+ private:
+  // Default number of entries in the table
+  enum SymbolHashMap_Constants {
+    _Def_HashMap_Size = 256
+  };
+
+  int                   _table_size;
+  SymbolHashMapBucket*  _buckets;
+
+  void initialize_table(int table_size) {
+    _table_size = table_size;
+    _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size, mtSymbol);
+    for (int index = 0; index < table_size; index++) {
+      _buckets[index].clear();
+    }
+  }
+
+ public:
+
+  int table_size() const        { return _table_size; }
+
+  SymbolHashMap()               { initialize_table(_Def_HashMap_Size); }
+  SymbolHashMap(int table_size) { initialize_table(table_size); }
+
+  // hash P(31) from Kernighan & Ritchie
+  static unsigned int compute_hash(const char* str, int len) {
+    unsigned int hash = 0;
+    while (len-- > 0) {
+      hash = 31*hash + (unsigned) *str;
+      str++;
+    }
+    return hash;
+  }
+
+  SymbolHashMapEntry* bucket(int i) {
+    return _buckets[i].entry();
+  }
+
+  void add_entry(Symbol* sym, u2 value);
+  SymbolHashMapEntry* find_entry(Symbol* sym);
+
+  u2 symbol_to_value(Symbol* sym) {
+    SymbolHashMapEntry *entry = find_entry(sym);
+    return (entry == NULL) ? 0 : entry->value();
+  }
+
+  ~SymbolHashMap() {
+    SymbolHashMapEntry* next;
+    for (int i = 0; i < _table_size; i++) {
+      for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
+        next = cur->next();
+        delete(cur);
+      }
+    }
+    delete _buckets;
+  }
+}; // End SymbolHashMap class
+
+#endif // SHARE_VM_OOPS_CONSTANTPOOLOOP_HPP