单步调试java main方法在hotspot中的解释执行

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int JNICALL
JavaMain(void * _args)
{	
  	......
    mainID = (*env)->GetStaticMethodID(env, mainClass, "main",
                                       "([Ljava/lang/String;)V");

    /* Build platform specific argument array */
    mainArgs = CreateApplicationArgs(env, argv, argc);
    CHECK_EXCEPTION_NULL_LEAVE(mainArgs);

    /* Invoke main method. */
    (*env)->CallStaticVoidMethod(env, mainClass, mainID, mainArgs); // line 472

    ret = (*env)->ExceptionOccurred(env) == NULL ? 0 : 1;
    LEAVE();
}

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void JavaCalls::call_helper(JavaValue* result, methodHandle* m, JavaCallArguments* args, TRAPS) {
  ......
  address entry_point = method->from_interpreted_entry();
  if (JvmtiExport::can_post_interpreter_events() && thread->is_interp_only_mode()) {
    entry_point = method->interpreter_entry();
  }
  
  // do call
  { JavaCallWrapper link(method, receiver, result, CHECK);
    { HandleMark hm(thread);  

      StubRoutines::call_stub()(	// line 393
        (address)&link,
        // (intptr_t*)&(result->_value), 
        result_val_address,          
        result_type,
        method(),
        entry_point,
        args->parameters(),
        args->size_of_parameters(),
        CHECK
      );

      result = link.result();
    }
  } 
}

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address generate_call_stub(address& return_address) {
    StubCodeMark mark(this, "StubRoutines", "call_stub");
    address start = __ pc();

    // same as in generate_catch_exception()!
    const Address rsp_after_call(rbp, rsp_after_call_off * wordSize); 

    // rbp： CONSTANT_REGISTER_DECLARATION(Register, rbp,    (5))
    // class Address: hotspot/src/cpu/x86/vm/assembler_x86.hpp
    const Address call_wrapper  (rbp, call_wrapper_off   * wordSize);
    const Address result        (rbp, result_off         * wordSize);
    const Address result_type   (rbp, result_type_off    * wordSize);
    const Address method        (rbp, method_off         * wordSize);
    const Address entry_point   (rbp, entry_point_off    * wordSize);
    const Address parameters    (rbp, parameters_off     * wordSize);
    const Address parameter_size(rbp, parameter_size_off * wordSize);

    // same as in generate_catch_exception()!
    const Address thread        (rbp, thread_off         * wordSize);

    const Address r15_save(rbp, r15_off * wordSize);
    const Address r14_save(rbp, r14_off * wordSize);
    const Address r13_save(rbp, r13_off * wordSize);
    const Address r12_save(rbp, r12_off * wordSize);
    const Address rbx_save(rbp, rbx_off * wordSize);

    // stub code
    __ enter();
    __ subptr(rsp, -rsp_after_call_off * wordSize);
  	......
      
    // call Java function
    __ BIND(parameters_done);
    __ movptr(rbx, method);             // get Method*
    __ movptr(c_rarg1, entry_point);    // get entry_point
    __ mov(r13, rsp);                   // set sender sp
    BLOCK_COMMENT("call Java function");
    __ call(c_rarg1);

    BLOCK_COMMENT("call_stub_return_address:");
    return_address = __ pc();
    ......
}

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// Call stubs are used to call Java from C
  //
  // Linux Arguments:
  //    c_rarg0:   call wrapper address                   address
  //    c_rarg1:   result                                 address
  //    c_rarg2:   result type                            BasicType
  //    c_rarg3:   method                                 Method*
  //    c_rarg4:   (interpreter) entry point              address
  //    c_rarg5:   parameters                             intptr_t*
  //    16(rbp): parameter size (in words)              int
  //    24(rbp): thread                                 Thread*
  //
  //     [ return_from_Java     ] <--- rsp
  //     [ argument word n      ]
  //      ...
  // -12 [ argument word 1      ]
  // -11 [ saved r15            ] <--- rsp_after_call
  // -10 [ saved r14            ]
  //  -9 [ saved r13            ]
  //  -8 [ saved r12            ]
  //  -7 [ saved rbx            ]
  //  -6 [ call wrapper         ]
  //  -5 [ result               ]
  //  -4 [ result type          ]
  //  -3 [ method               ]
  //  -2 [ entry point          ]
  //  -1 [ parameters           ]
  //   0 [ saved rbp            ] <--- rbp
  //   1 [ return address       ]
  //   2 [ parameter size       ]
  //   3 [ thread               ]

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//
// Generic interpreted method entry to (asm) interpreter
//
address InterpreterGenerator::generate_normal_entry(bool synchronized) {
  // determine code generation flags
  bool inc_counter  = UseCompiler || CountCompiledCalls;

  // ebx: Method*
  // r13: sender sp
  address entry_point = __ pc();

  const Address constMethod(rbx, Method::const_offset());
  const Address access_flags(rbx, Method::access_flags_offset());
  const Address size_of_parameters(rdx,
                                   ConstMethod::size_of_parameters_offset());
  const Address size_of_locals(rdx, ConstMethod::size_of_locals_offset());


  // get parameter size (always needed)
  // note: rdx as a local var set here kind of violate intuition, but not set 
  //  before size_of_parameters. It is tested ok to move "__ movptr(rdx, constMethod)" before size_of_parameters
  __ movptr(rdx, constMethod);
  __ load_unsigned_short(rcx, size_of_parameters);

  // rbx: Method*
  // rcx: size of parameters
  // r13: sender_sp (could differ from sp+wordSize if we were called via c2i )

  __ load_unsigned_short(rdx, size_of_locals); // get size of locals in words
  __ subl(rdx, rcx); // rdx = no. of additional locals

  // see if we've got enough room on the stack for locals plus overhead.
  generate_stack_overflow_check();

  // get return address
  __ pop(rax);

  // compute beginning of parameters (r14)
  __ lea(r14, Address(rsp, rcx, Address::times_8, -wordSize));

  // rdx - # of additional locals
  // allocate space for locals
  // explicitly initialize locals
  {
    Label exit, loop;
    __ testl(rdx, rdx);
    __ jcc(Assembler::lessEqual, exit); // do nothing if rdx <= 0
    __ bind(loop);
    __ push((int) NULL_WORD); // initialize local variables
    __ decrementl(rdx); // until everything initialized
    __ jcc(Assembler::greater, loop);
    __ bind(exit);
  }

  // initialize fixed part of activation frame
  generate_fixed_frame(false);
  ......
  __ dispatch_next(vtos);
  
  return entry_point;
}

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void InterpreterMacroAssembler::dispatch_next(TosState state, int step) {
  // load next bytecode (load before advancing r13 to prevent AGI)
  load_unsigned_byte(rbx, Address(r13, step));
  // advance r13
  increment(r13, step);
  dispatch_base(state, Interpreter::dispatch_table(state));
}

void InterpreterMacroAssembler::dispatch_base(TosState state,
                                              address* table,
                                              bool verifyoop) {
  ......
  lea(rscratch1, ExternalAddress((address)table));
  jmp(Address(rscratch1, rbx, Address::times_8));
}