/*

 * 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.

 *

 *

 */

#include "incls/_precompiled.incl"

#include "incls/_runtime_x86_32.cpp.incl"

#define __ masm->

ExceptionBlob*     OptoRuntime::_exception_blob;

//------------------------------generate_exception_blob---------------------------

// creates exception blob at the end

// Using exception blob, this code is jumped from a compiled method.

//

// Given an exception pc at a call we call into the runtime for the

// handler in this method. This handler might merely restore state

// (i.e. callee save registers) unwind the frame and jump to the

// exception handler for the nmethod if there is no Java level handler

// for the nmethod.

//

// This code is entered with a jmp.

//

// Arguments:

//   rax: exception oop

//   rdx: exception pc

//

// Results:

//   rax: exception oop

//   rdx: exception pc in caller or ???

//   destination: exception handler of caller

//

// Note: the exception pc MUST be at a call (precise debug information)

//       Only register rax, rdx, rcx are not callee saved.

//

void OptoRuntime::generate_exception_blob() {

  // Capture info about frame layout

  enum layout {

    thread_off,                 // last_java_sp

    // The frame sender code expects that rbp will be in the "natural" place and

    // will override any oopMap setting for it. We must therefore force the layout

    // so that it agrees with the frame sender code.

    rbp_off,

    return_off,                 // slot for return address

    framesize

  };

  // allocate space for the code

  ResourceMark rm;

  // setup code generation tools

  CodeBuffer   buffer("exception_blob", 512, 512);

  MacroAssembler* masm = new MacroAssembler(&buffer);

  OopMapSet *oop_maps = new OopMapSet();

  address start = __ pc();

  __ push(rdx);

  __ subptr(rsp, return_off * wordSize);   // Prolog!

  // rbp, location is implicitly known

  __ movptr(Address(rsp,rbp_off  *wordSize), rbp);

  // Store exception in Thread object. We cannot pass any arguments to the

  // handle_exception call, since we do not want to make any assumption

  // about the size of the frame where the exception happened in.

  __ get_thread(rcx);

  __ movptr(Address(rcx, JavaThread::exception_oop_offset()), rax);

  __ movptr(Address(rcx, JavaThread::exception_pc_offset()),  rdx);

  // This call does all the hard work.  It checks if an exception handler

  // exists in the method.

  // If so, it returns the handler address.

  // If not, it prepares for stack-unwinding, restoring the callee-save

  // registers of the frame being removed.

  //

  __ movptr(Address(rsp, thread_off * wordSize), rcx); // Thread is first argument

  __ set_last_Java_frame(rcx, noreg, noreg, NULL);

  __ call(RuntimeAddress(CAST_FROM_FN_PTR(address, OptoRuntime::handle_exception_C)));

  // No registers to map, rbp is known implicitly

  oop_maps->add_gc_map( __ pc() - start,  new OopMap( framesize, 0 ));

  __ get_thread(rcx);

  __ reset_last_Java_frame(rcx, false, false);

  // Restore callee-saved registers

  __ movptr(rbp, Address(rsp, rbp_off * wordSize));

  __ addptr(rsp, return_off * wordSize);   // Epilog!

  __ pop(rdx); // Exception pc

  // rax: exception handler for given <exception oop/exception pc>

  // Restore SP from BP if the exception PC is a MethodHandle call site.

  __ cmpl(Address(rcx, JavaThread::is_method_handle_return_offset()), 0);

  __ cmovptr(Assembler::notEqual, rsp, rbp);

  // We have a handler in rax, (could be deopt blob)

  // rdx - throwing pc, deopt blob will need it.

  __ push(rax);

  // Get the exception

  __ movptr(rax, Address(rcx, JavaThread::exception_oop_offset()));

  // Get the exception pc in case we are deoptimized

  __ movptr(rdx, Address(rcx, JavaThread::exception_pc_offset()));

#ifdef ASSERT

  __ movptr(Address(rcx, JavaThread::exception_handler_pc_offset()), NULL_WORD);

  __ movptr(Address(rcx, JavaThread::exception_pc_offset()), NULL_WORD);

#endif

  // Clear the exception oop so GC no longer processes it as a root.

  __ movptr(Address(rcx, JavaThread::exception_oop_offset()), NULL_WORD);

  __ pop(rcx);

  // rax: exception oop

  // rcx: exception handler

  // rdx: exception pc

  __ jmp (rcx);

  // -------------

  // make sure all code is generated

  masm->flush();

  _exception_blob = ExceptionBlob::create(&buffer, oop_maps, framesize);

}