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Java example source code file (bytecode.cpp)

This example Java source code file (bytecode.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

assert, basictype, bytecodes::_all_fmt_bits, bytecodes::_fmt_not_simple, bytecodes::code, bytecodes::flags, bytecodes\:\:_fmt_bc, bytecodes\:\:_fmt_has_u2, bytecodes\:\:_fmt_has_u4, bytecodes\:\:_wide, bytecodes\:\:java_code, constantpoolcacheentry, handle, symbol

The bytecode.cpp Java example source code

/*
 * 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.
 *
 */

#include "precompiled.hpp"
#include "interpreter/bytecode.hpp"
#include "interpreter/linkResolver.hpp"
#include "oops/constantPool.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/fieldType.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/signature.hpp"

// Implementation of Bytecode

#ifdef ASSERT

void Bytecode::assert_same_format_as(Bytecodes::Code testbc, bool is_wide) const {
  Bytecodes::Code thisbc = Bytecodes::cast(byte_at(0));
  if (thisbc == Bytecodes::_breakpoint)  return;  // let the assertion fail silently
  if (is_wide) {
    assert(thisbc == Bytecodes::_wide, "expected a wide instruction");
    thisbc = Bytecodes::cast(byte_at(1));
    if (thisbc == Bytecodes::_breakpoint)  return;
  }
  int thisflags = Bytecodes::flags(testbc, is_wide) & Bytecodes::_all_fmt_bits;
  int testflags = Bytecodes::flags(thisbc, is_wide) & Bytecodes::_all_fmt_bits;
  if (thisflags != testflags)
    tty->print_cr("assert_same_format_as(%d) failed on bc=%d%s; %d != %d",
                  (int)testbc, (int)thisbc, (is_wide?"/wide":""), testflags, thisflags);
  assert(thisflags == testflags, "expected format");
}

void Bytecode::assert_index_size(int size, Bytecodes::Code bc, bool is_wide) {
  int have_fmt = (Bytecodes::flags(bc, is_wide)
                  & (Bytecodes::_fmt_has_u2 | Bytecodes::_fmt_has_u4 |
                     Bytecodes::_fmt_not_simple |
                     // Not an offset field:
                     Bytecodes::_fmt_has_o));
  int need_fmt = -1;
  switch (size) {
  case 1: need_fmt = 0;                      break;
  case 2: need_fmt = Bytecodes::_fmt_has_u2; break;
  case 4: need_fmt = Bytecodes::_fmt_has_u4; break;
  }
  if (is_wide)  need_fmt |= Bytecodes::_fmt_not_simple;
  if (have_fmt != need_fmt) {
    tty->print_cr("assert_index_size %d: bc=%d%s %d != %d", size, bc, (is_wide?"/wide":""), have_fmt, need_fmt);
    assert(have_fmt == need_fmt, "assert_index_size");
  }
}

void Bytecode::assert_offset_size(int size, Bytecodes::Code bc, bool is_wide) {
  int have_fmt = Bytecodes::flags(bc, is_wide) & Bytecodes::_all_fmt_bits;
  int need_fmt = -1;
  switch (size) {
  case 2: need_fmt = Bytecodes::_fmt_bo2; break;
  case 4: need_fmt = Bytecodes::_fmt_bo4; break;
  }
  if (is_wide)  need_fmt |= Bytecodes::_fmt_not_simple;
  if (have_fmt != need_fmt) {
    tty->print_cr("assert_offset_size %d: bc=%d%s %d != %d", size, bc, (is_wide?"/wide":""), have_fmt, need_fmt);
    assert(have_fmt == need_fmt, "assert_offset_size");
  }
}

void Bytecode::assert_constant_size(int size, int where, Bytecodes::Code bc, bool is_wide) {
  int have_fmt = Bytecodes::flags(bc, is_wide) & (Bytecodes::_all_fmt_bits
                                                  // Ignore any 'i' field (for iinc):
                                                  & ~Bytecodes::_fmt_has_i);
  int need_fmt = -1;
  switch (size) {
  case 1: need_fmt = Bytecodes::_fmt_bc;                          break;
  case 2: need_fmt = Bytecodes::_fmt_bc | Bytecodes::_fmt_has_u2; break;
  }
  if (is_wide)  need_fmt |= Bytecodes::_fmt_not_simple;
  int length = is_wide ? Bytecodes::wide_length_for(bc) : Bytecodes::length_for(bc);
  if (have_fmt != need_fmt || where + size != length) {
    tty->print_cr("assert_constant_size %d @%d: bc=%d%s %d != %d", size, where, bc, (is_wide?"/wide":""), have_fmt, need_fmt);
  }
  assert(have_fmt == need_fmt, "assert_constant_size");
  assert(where + size == length, "assert_constant_size oob");
}

void Bytecode::assert_native_index(Bytecodes::Code bc, bool is_wide) {
  assert((Bytecodes::flags(bc, is_wide) & Bytecodes::_fmt_has_nbo) != 0, "native index");
}

#endif //ASSERT

// Implementation of Bytecode_tableupswitch

int Bytecode_tableswitch::dest_offset_at(int i) const {
  return get_Java_u4_at(aligned_offset(1 + (3 + i)*jintSize));
}


// Implementation of Bytecode_invoke

void Bytecode_invoke::verify() const {
  assert(is_valid(), "check invoke");
  assert(cpcache() != NULL, "do not call this from verifier or rewriter");
}


Symbol* Bytecode_member_ref::klass() const {
  return constants()->klass_ref_at_noresolve(index());
}


Symbol* Bytecode_member_ref::name() const {
  return constants()->name_ref_at(index());
}


Symbol* Bytecode_member_ref::signature() const {
  return constants()->signature_ref_at(index());
}


BasicType Bytecode_member_ref::result_type() const {
  ResultTypeFinder rts(signature());
  rts.iterate();
  return rts.type();
}


methodHandle Bytecode_invoke::static_target(TRAPS) {
  methodHandle m;
  KlassHandle resolved_klass;
  constantPoolHandle constants(THREAD, this->constants());

  Bytecodes::Code bc = invoke_code();
  LinkResolver::resolve_method_statically(m, resolved_klass, bc, constants, index(), CHECK_(methodHandle()));
  return m;
}

Handle Bytecode_invoke::appendix(TRAPS) {
  ConstantPoolCacheEntry* cpce = cpcache_entry();
  if (cpce->has_appendix())
    return Handle(THREAD, cpce->appendix_if_resolved(constants()));
  return Handle();  // usual case
}

int Bytecode_member_ref::index() const {
  // Note:  Rewriter::rewrite changes the Java_u2 of an invokedynamic to a native_u4,
  // at the same time it allocates per-call-site CP cache entries.
  Bytecodes::Code rawc = code();
  if (has_index_u4(rawc))
    return get_index_u4(rawc);
  else
    return get_index_u2_cpcache(rawc);
}

int Bytecode_member_ref::pool_index() const {
  return cpcache_entry()->constant_pool_index();
}

ConstantPoolCacheEntry* Bytecode_member_ref::cpcache_entry() const {
  int index = this->index();
  return cpcache()->entry_at(ConstantPool::decode_cpcache_index(index, true));
}

// Implementation of Bytecode_field

void Bytecode_field::verify() const {
  assert(is_valid(), "check field");
}


// Implementation of Bytecode_loadconstant

int Bytecode_loadconstant::raw_index() const {
  Bytecodes::Code rawc = code();
  assert(rawc != Bytecodes::_wide, "verifier prevents this");
  if (Bytecodes::java_code(rawc) == Bytecodes::_ldc)
    return get_index_u1(rawc);
  else
    return get_index_u2(rawc, false);
}

int Bytecode_loadconstant::pool_index() const {
  int index = raw_index();
  if (has_cache_index()) {
    return _method->constants()->object_to_cp_index(index);
  }
  return index;
}

BasicType Bytecode_loadconstant::result_type() const {
  int index = pool_index();
  constantTag tag = _method->constants()->tag_at(index);
  return tag.basic_type();
}

oop Bytecode_loadconstant::resolve_constant(TRAPS) const {
  assert(_method.not_null(), "must supply method to resolve constant");
  int index = raw_index();
  ConstantPool* constants = _method->constants();
  if (has_cache_index()) {
    return constants->resolve_cached_constant_at(index, THREAD);
  } else {
    return constants->resolve_constant_at(index, THREAD);
  }
}

//------------------------------------------------------------------------------
// Non-product code

#ifndef PRODUCT

void Bytecode_lookupswitch::verify() const {
  switch (Bytecodes::java_code(code())) {
    case Bytecodes::_lookupswitch:
      { int i = number_of_pairs() - 1;
        while (i-- > 0) {
          assert(pair_at(i).match() < pair_at(i+1).match(), "unsorted table entries");
        }
      }
      break;
    default:
      fatal("not a lookupswitch bytecode");
  }
}

void Bytecode_tableswitch::verify() const {
  switch (Bytecodes::java_code(code())) {
    case Bytecodes::_tableswitch:
      { int lo = low_key();
        int hi = high_key();
        assert (hi >= lo, "incorrect hi/lo values in tableswitch");
        int i  = hi - lo - 1 ;
        while (i-- > 0) {
          // no special check needed
        }
      }
      break;
    default:
      fatal("not a tableswitch bytecode");
  }
}

#endif

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