/*

 * Copyright (c) 2012, 2019, 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_CLASSFILE_BYTECODEASSEMBLER_HPP

#define SHARE_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 {

 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 _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_CLASSFILE_BYTECODEASSEMBLER_HPP