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 /*

  * Copyright (c) 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_CLASSFILE_BYTECODEASSEMBLER_HPP

 #define SHARE_VM_CLASSFILE_BYTECODEASSEMBLER_HPP

 #include "memory/allocation.hpp"

 #include "oops/method.hpp"

 #include "oops/symbol.hpp"

 #include "utilities/globalDefinitions.hpp"

 #include "utilities/growableArray.hpp"

 #include "utilities/resourceHash.hpp"

 /**

  * Bytecode Assembler

  *

  * These classes are used to synthesize code for creating new methods from

  * within the VM.  This is only a partial implementation of an assembler;

  * only the bytecodes that are needed by clients are implemented at this time.

  * This is used during default method analysis to create overpass methods

  * and add them to a call during parsing.  Other uses (such as creating

  * bridges) may come later.  Any missing bytecodes can be implemented on an

  * as-need basis.

  */

 class BytecodeBuffer : public GrowableArray<u1> {

  public:

   BytecodeBuffer() : GrowableArray<u1>(20) {}

 };

 // Entries in a yet-to-be-created constant pool.  Limited types for now.

 class BytecodeCPEntry VALUE_OBJ_CLASS_SPEC {

  public:

   enum tag {

     ERROR_TAG,

     UTF8,

     KLASS,

     STRING,

     NAME_AND_TYPE,

     METHODREF

   };

   u1 _tag;

   union {

     Symbol* utf8;

     u2 klass;

     u2 string;

     struct {

       u2 name_index;

       u2 type_index;

     } name_and_type;

     struct {

       u2 class_index;

       u2 name_and_type_index;

     } methodref;

     uintptr_t hash;

   } _u;

   BytecodeCPEntry() : _tag(ERROR_TAG) { _u.hash = 0; }

   BytecodeCPEntry(u1 tag) : _tag(tag) { _u.hash = 0; }

   static BytecodeCPEntry utf8(Symbol* symbol) {

     BytecodeCPEntry bcpe(UTF8);

     bcpe._u.utf8 = symbol;

     return bcpe;

   }

   static BytecodeCPEntry klass(u2 index) {

     BytecodeCPEntry bcpe(KLASS);

     bcpe._u.klass = index;

     return bcpe;

   }

   static BytecodeCPEntry string(u2 index) {

     BytecodeCPEntry bcpe(STRING);

     bcpe._u.string = index;

     return bcpe;

   }

   static BytecodeCPEntry name_and_type(u2 name, u2 type) {

     BytecodeCPEntry bcpe(NAME_AND_TYPE);

     bcpe._u.name_and_type.name_index = name;

     bcpe._u.name_and_type.type_index = type;

     return bcpe;

   }

   static BytecodeCPEntry methodref(u2 class_index, u2 nat) {

     BytecodeCPEntry bcpe(METHODREF);

     bcpe._u.methodref.class_index = class_index;

     bcpe._u.methodref.name_and_type_index = nat;

     return bcpe;

   }

   static bool equals(BytecodeCPEntry const& e0, BytecodeCPEntry const& e1) {

     return e0._tag == e1._tag && e0._u.hash == e1._u.hash;

   }

   static unsigned hash(BytecodeCPEntry const& e0) {

     return (unsigned)(e0._tag ^ e0._u.hash);

   }

 };

 class BytecodeConstantPool : ResourceObj {

  private:

   typedef ResourceHashtable<BytecodeCPEntry, u2,

       &BytecodeCPEntry::hash, &BytecodeCPEntry::equals> IndexHash;

   ConstantPool* _orig;

   GrowableArray<BytecodeCPEntry> _entries;

   IndexHash _indices;

   u2 find_or_add(BytecodeCPEntry const& bcpe);

  public:

   BytecodeConstantPool(ConstantPool* orig) : _orig(orig) {}

   BytecodeCPEntry const& at(u2 index) const { return _entries.at(index); }

   InstanceKlass* pool_holder() const {

     return InstanceKlass::cast(_orig->pool_holder());

   }

   u2 utf8(Symbol* sym) {

     return find_or_add(BytecodeCPEntry::utf8(sym));

   }

   u2 klass(Symbol* class_name) {

     return find_or_add(BytecodeCPEntry::klass(utf8(class_name)));

   }

   u2 string(Symbol* str) {

     return find_or_add(BytecodeCPEntry::string(utf8(str)));

   }

   u2 name_and_type(Symbol* name, Symbol* sig) {

     return find_or_add(BytecodeCPEntry::name_and_type(utf8(name), utf8(sig)));

   }

   u2 methodref(Symbol* class_name, Symbol* name, Symbol* sig) {

     return find_or_add(BytecodeCPEntry::methodref(

         klass(class_name), name_and_type(name, sig)));

   }

   ConstantPool* create_constant_pool(TRAPS) const;

 };

 // Partial bytecode assembler - only what we need for creating

 // overpass methods for default methods is implemented

 class BytecodeAssembler : StackObj {

  private:

   BytecodeBuffer* _code;

   BytecodeConstantPool* _cp;

   void append(u1 imm_u1);

   void append(u2 imm_u2);

   void append(u4 imm_u4);

   void xload(u4 index, u1 quick, u1 twobyte);

  public:

   BytecodeAssembler(BytecodeBuffer* buffer, BytecodeConstantPool* cp)

     : _code(buffer), _cp(cp) {}

   void aload(u4 index);

   void areturn();

   void athrow();

   void checkcast(Symbol* sym);

   void dload(u4 index);

   void dreturn();

   void dup();

   void fload(u4 index);

   void freturn();

   void iload(u4 index);

   void invokespecial(Method* method);

   void invokespecial(Symbol* cls, Symbol* name, Symbol* sig);

   void invokevirtual(Method* method);

   void invokevirtual(Symbol* cls, Symbol* name, Symbol* sig);

   void ireturn();

   void ldc(u1 index);

   void ldc_w(u2 index);

   void lload(u4 index);

   void lreturn();

   void _new(Symbol* sym);

   void _return();

   void load_string(Symbol* sym);

   void load(BasicType bt, u4 index);

   void _return(BasicType bt);

 };

 #endif // SHARE_VM_CLASSFILE_BYTECODEASSEMBLER_HPP