C++ methodOop::code_base方法代码示例

  void trace(methodOop method, address bcp, uintptr_t tos, uintptr_t tos2) {
#ifndef PRODUCT
    MutexLocker ml(BytecodeTrace_lock);
    if (_current_method != method) {
      // Note 1: This code will not work as expected with true MT/MP.
      //         Need an explicit lock or a different solution.
      ResourceMark rm;
      tty->cr();
      tty->print("[%d] ", (int) Thread::current()->osthread()->thread_id());
      method->print_name(tty);
      tty->cr();
      _current_method = method;
    }
    if (Verbose) {
      const char* format;
      switch (Bytecodes::length_at(bcp)) {
        case  1: format = "%x  %02x         "    ; break;
        case  2: format = "%x  %02x %02x      "  ; break;
        case  3: format = "%x  %02x %02x %02x   "; break;
        default: format = "%x  %02x %02x %02x .."; break;
      }
      tty->print(format, bcp, *bcp, *(bcp+1), *(bcp+2));
    }
    Bytecodes::Code code;
    if (_previous_bytecode == Bytecodes::_wide) {
      code = Bytecodes::cast(*(bcp+1));
    } else {
      code = Bytecodes::cast(*bcp);
    }
    int bci = bcp - method->code_base();
    const char* format = _previous_bytecode == Bytecodes::_wide ? Bytecodes::wide_format(code) : Bytecodes::format(code);
    tty->print("[%d] ", (int) Thread::current()->osthread()->thread_id());
    if (Verbose) {
      tty->print("%8d  %4d  0x%016lx 0x%016lx %s", 
	   BytecodeCounter::counter_value(), bci, tos, tos2, Bytecodes::name(code));
    } else {
      tty->print("%8d  %4d  %s", 
	   BytecodeCounter::counter_value(), bci, Bytecodes::name(code));
    }
    print_attributes(bcp, bci, format);
    tty->cr();
    _previous_bytecode = code;
#endif
  }

// Given that a new (potential) event has come in,
// maintain the current JVMTI location on a per-thread per-env basis
// and use it to filter out duplicate events:
// - instruction rewrites
// - breakpoint followed by single step
// - single step at a breakpoint
void JvmtiEnvThreadState::compare_and_set_current_location(methodOop new_method,
                                                           address new_location, jvmtiEvent event) {

  int new_bci = new_location - new_method->code_base();

  // The method is identified and stored as a jmethodID which is safe in this
  // case because the class cannot be unloaded while a method is executing.
  jmethodID new_method_id = new_method->jmethod_id();

  // the last breakpoint or single step was at this same location
  if (_current_bci == new_bci && _current_method_id == new_method_id) {
    switch (event) {
    case JVMTI_EVENT_BREAKPOINT:
      // Repeat breakpoint is complicated. If we previously posted a breakpoint
      // event at this location and if we also single stepped at this location
      // then we skip the duplicate breakpoint.
      _breakpoint_posted = _breakpoint_posted && _single_stepping_posted;
      break;
    case JVMTI_EVENT_SINGLE_STEP:
      // Repeat single step is easy: just don't post it again.
      // If step is pending for popframe then it may not be
      // a repeat step. The new_bci and method_id is same as current_bci
      // and current method_id after pop and step for recursive calls.
      // This has been handled by clearing the location
      _single_stepping_posted = true;
      break;
    default:
      assert(false, "invalid event value passed");
      break;
    }
    return;
  }

  set_current_location(new_method_id, new_bci);
  _breakpoint_posted = false;
  _single_stepping_posted = false;
}

int CppInterpreter::accessor_entry(methodOop method, intptr_t UNUSED, TRAPS) {
  JavaThread *thread = (JavaThread *) THREAD;
  ZeroStack *stack = thread->zero_stack();
  intptr_t *locals = stack->sp();

  // Drop into the slow path if we need a safepoint check
  if (SafepointSynchronize::do_call_back()) {
    return normal_entry(method, 0, THREAD);
  }

  // Load the object pointer and drop into the slow path
  // if we have a NullPointerException
  oop object = LOCALS_OBJECT(0);
  if (object == NULL) {
    return normal_entry(method, 0, THREAD);
  }

  // Read the field index from the bytecode, which looks like this:
  //  0:  aload_0
  //  1:  getfield
  //  2:    index
  //  3:    index
  //  4:  ireturn/areturn
  // NB this is not raw bytecode: index is in machine order
  u1 *code = method->code_base();
  assert(code[0] == Bytecodes::_aload_0 &&
         code[1] == Bytecodes::_getfield &&
         (code[4] == Bytecodes::_ireturn ||
          code[4] == Bytecodes::_areturn), "should do");
  u2 index = Bytes::get_native_u2(&code[2]);

  // Get the entry from the constant pool cache, and drop into
  // the slow path if it has not been resolved
  constantPoolCacheOop cache = method->constants()->cache();
  ConstantPoolCacheEntry* entry = cache->entry_at(index);
  if (!entry->is_resolved(Bytecodes::_getfield)) {
    return normal_entry(method, 0, THREAD);
  }

  // Get the result and push it onto the stack
  switch (entry->flag_state()) {
  case ltos:
  case dtos:
    stack->overflow_check(1, CHECK_0);
    stack->alloc(wordSize);
    break;
  }
  if (entry->is_volatile()) {
    switch (entry->flag_state()) {
    case ctos:
      SET_LOCALS_INT(object->char_field_acquire(entry->f2()), 0);
      break;

    case btos:
      SET_LOCALS_INT(object->byte_field_acquire(entry->f2()), 0);
      break;

    case stos:
      SET_LOCALS_INT(object->short_field_acquire(entry->f2()), 0);
      break;

    case itos:
      SET_LOCALS_INT(object->int_field_acquire(entry->f2()), 0);
      break;

    case ltos:
      SET_LOCALS_LONG(object->long_field_acquire(entry->f2()), 0);
      break;

    case ftos:
      SET_LOCALS_FLOAT(object->float_field_acquire(entry->f2()), 0);
      break;

    case dtos:
      SET_LOCALS_DOUBLE(object->double_field_acquire(entry->f2()), 0);
      break;

    case atos:
      SET_LOCALS_OBJECT(object->obj_field_acquire(entry->f2()), 0);
      break;

    default:
      ShouldNotReachHere();
    }
  }
  else {
    switch (entry->flag_state()) {
    case ctos:
      SET_LOCALS_INT(object->char_field(entry->f2()), 0);
      break;

    case btos:
      SET_LOCALS_INT(object->byte_field(entry->f2()), 0);
      break;

    case stos:
      SET_LOCALS_INT(object->short_field(entry->f2()), 0);
      break;

    case itos:
//.........这里部分代码省略.........

// Rewrites a method given the index_map information
void Rewriter::scan_method(methodOop method, bool reverse) {

  int nof_jsrs = 0;
  bool has_monitor_bytecodes = false;

  {
    // We cannot tolerate a GC in this block, because we've
    // cached the bytecodes in 'code_base'. If the methodOop
    // moves, the bytecodes will also move.
    No_Safepoint_Verifier nsv;
    Bytecodes::Code c;

    // Bytecodes and their length
    const address code_base = method->code_base();
    const int code_length = method->code_size();

    int bc_length;
    for (int bci = 0; bci < code_length; bci += bc_length) {
      address bcp = code_base + bci;
      int prefix_length = 0;
      c = (Bytecodes::Code)(*bcp);

      // Since we have the code, see if we can get the length
      // directly. Some more complicated bytecodes will report
      // a length of zero, meaning we need to make another method
      // call to calculate the length.
      bc_length = Bytecodes::length_for(c);
      if (bc_length == 0) {
        bc_length = Bytecodes::length_at(method, bcp);

        // length_at will put us at the bytecode after the one modified
        // by 'wide'. We don't currently examine any of the bytecodes
        // modified by wide, but in case we do in the future...
        if (c == Bytecodes::_wide) {
          prefix_length = 1;
          c = (Bytecodes::Code)bcp[1];
        }
      }

      assert(bc_length != 0, "impossible bytecode length");

      switch (c) {
        case Bytecodes::_lookupswitch   : {
#ifndef CC_INTERP
          Bytecode_lookupswitch bc(method, bcp);
          (*bcp) = (
            bc.number_of_pairs() < BinarySwitchThreshold
            ? Bytecodes::_fast_linearswitch
            : Bytecodes::_fast_binaryswitch
          );
#endif
          break;
        }
        case Bytecodes::_fast_linearswitch:
        case Bytecodes::_fast_binaryswitch: {
#ifndef CC_INTERP
          (*bcp) = Bytecodes::_lookupswitch;
#endif
          break;
        }
        case Bytecodes::_getstatic      : // fall through
        case Bytecodes::_putstatic      : // fall through
        case Bytecodes::_getfield       : // fall through
        case Bytecodes::_putfield       : // fall through
        case Bytecodes::_invokevirtual  : // fall through
        case Bytecodes::_invokespecial  : // fall through
        case Bytecodes::_invokestatic   :
        case Bytecodes::_invokeinterface:
          rewrite_member_reference(bcp, prefix_length+1, reverse);
          break;
        case Bytecodes::_invokedynamic:
          rewrite_invokedynamic(bcp, prefix_length+1, reverse);
          break;
        case Bytecodes::_ldc:
        case Bytecodes::_fast_aldc:
          maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);
          break;
        case Bytecodes::_ldc_w:
        case Bytecodes::_fast_aldc_w:
          maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);
          break;
        case Bytecodes::_jsr            : // fall through
        case Bytecodes::_jsr_w          : nof_jsrs++;                   break;
        case Bytecodes::_monitorenter   : // fall through
        case Bytecodes::_monitorexit    : has_monitor_bytecodes = true; break;
      }
    }
  }

  // Update access flags
  if (has_monitor_bytecodes) {
    method->set_has_monitor_bytecodes();
  }

  // The present of a jsr bytecode implies that the method might potentially
  // have to be rewritten, so we run the oopMapGenerator on the method
  if (nof_jsrs > 0) {
    method->set_has_jsrs();
    // Second pass will revisit this method.
//.........这里部分代码省略.........