/*

 * Copyright (c) 1997, 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.

 *

 */

#include "precompiled.hpp"

#include "code/vtableStubs.hpp"

#include "compiler/compileBroker.hpp"

#include "compiler/disassembler.hpp"

#include "logging/log.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

#include "oops/instanceKlass.hpp"

#include "oops/klassVtable.hpp"

#include "oops/oop.inline.hpp"

#include "prims/forte.hpp"

#include "prims/jvmtiExport.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/sharedRuntime.hpp"

#include "utilities/align.hpp"

#ifdef COMPILER2

#include "opto/matcher.hpp"

#endif

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

// Implementation of VtableStub

address VtableStub::_chunk             = NULL;

address VtableStub::_chunk_end         = NULL;

VMReg   VtableStub::_receiver_location = VMRegImpl::Bad();

void* VtableStub::operator new(size_t size, int code_size) throw() {

  assert_lock_strong(VtableStubs_lock);

  assert(size == sizeof(VtableStub), "mismatched size");

  // compute real VtableStub size (rounded to nearest word)

  const int real_size = align_up(code_size + (int)sizeof(VtableStub), wordSize);

  // malloc them in chunks to minimize header overhead

  const int chunk_factor = 32;

  if (_chunk == NULL || _chunk + real_size > _chunk_end) {

    const int bytes = chunk_factor * real_size + pd_code_alignment();

   // There is a dependency on the name of the blob in src/share/vm/prims/jvmtiCodeBlobEvents.cpp

   // If changing the name, update the other file accordingly.

    VtableBlob* blob = VtableBlob::create("vtable chunks", bytes);

    if (blob == NULL) {

      return NULL;

    }

    _chunk = blob->content_begin();

    _chunk_end = _chunk + bytes;

    Forte::register_stub("vtable stub", _chunk, _chunk_end);

    align_chunk();

  }

  assert(_chunk + real_size <= _chunk_end, "bad allocation");

  void* res = _chunk;

  _chunk += real_size;

  align_chunk();

 return res;

}

void VtableStub::print_on(outputStream* st) const {

  st->print("vtable stub (index = %d, receiver_location = " INTX_FORMAT ", code = [" INTPTR_FORMAT ", " INTPTR_FORMAT "])",

             index(), p2i(receiver_location()), p2i(code_begin()), p2i(code_end()));

}

void VtableStub::print() const { print_on(tty); }

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

// Implementation of VtableStubs

//

// For each hash value there's a linked list of vtable stubs (with that

// hash value). Each list is anchored in a little hash _table, indexed

// by that hash value.

VtableStub* VtableStubs::_table[VtableStubs::N];

int VtableStubs::_number_of_vtable_stubs = 0;

int VtableStubs::_vtab_stub_size = 0;

int VtableStubs::_itab_stub_size = 0;

#if defined(PRODUCT)

  // These values are good for the PRODUCT case (no tracing).

  static const int first_vtableStub_size =  64;

  static const int first_itableStub_size = 256;

#else

  // These values are good for the non-PRODUCT case (when tracing can be switched on).

  // To find out, run test workload with

  //   -Xlog:vtablestubs=Trace -XX:+CountCompiledCalls -XX:+DebugVtables

  // and use the reported "estimate" value.

  // Here is a list of observed worst-case values:

  //               vtable  itable

  // aarch64:         460     324

  // arm:               ?       ?

  // ppc (linux, BE): 404     288

  // ppc (linux, LE): 356     276

  // ppc (AIX):       416     296

  // s390x:           408     256

  // Solaris-sparc:   792     348

  // x86 (Linux):     670     309

  // x86 (MacOS):     682     321

  static const int first_vtableStub_size = 1024;

  static const int first_itableStub_size =  512;

#endif

void VtableStubs::initialize() {

  VtableStub::_receiver_location = SharedRuntime::name_for_receiver();

  {

    MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);

    assert(_number_of_vtable_stubs == 0, "potential performance bug: VtableStubs initialized more than once");

    assert(is_power_of_2(N), "N must be a power of 2");

    for (int i = 0; i < N; i++) {

      _table[i] = NULL;

    }

  }

}

int VtableStubs::code_size_limit(bool is_vtable_stub) {

  if (is_vtable_stub) {

    return _vtab_stub_size > 0 ? _vtab_stub_size : first_vtableStub_size;

  } else { // itable stub

    return _itab_stub_size > 0 ? _itab_stub_size : first_itableStub_size;

  }

}   // code_size_limit

void VtableStubs::check_and_set_size_limit(bool is_vtable_stub,

                                           int  code_size,

                                           int  padding) {

  const char* name = is_vtable_stub ? "vtable" : "itable";

  guarantee(code_size <= code_size_limit(is_vtable_stub),

            "buffer overflow in %s stub, code_size is %d, limit is %d", name, code_size, code_size_limit(is_vtable_stub));

  if (is_vtable_stub) {

    if (log_is_enabled(Trace, vtablestubs)) {

      if ( (_vtab_stub_size > 0) && ((code_size + padding) > _vtab_stub_size) ) {

        log_trace(vtablestubs)("%s size estimate needed adjustment from %d to %d bytes",

                               name, _vtab_stub_size, code_size + padding);

      }

    }

    if ( (code_size + padding) > _vtab_stub_size ) {

      _vtab_stub_size = code_size + padding;

    }

  } else {  // itable stub

    if (log_is_enabled(Trace, vtablestubs)) {

      if ( (_itab_stub_size > 0) && ((code_size + padding) > _itab_stub_size) ) {

        log_trace(vtablestubs)("%s size estimate needed adjustment from %d to %d bytes",

                               name, _itab_stub_size, code_size + padding);

      }

    }

    if ( (code_size + padding) > _itab_stub_size ) {

      _itab_stub_size = code_size + padding;

    }

  }

  return;

}   // check_and_set_size_limit

void VtableStubs::bookkeeping(MacroAssembler* masm, outputStream* out, VtableStub* s,

                              address npe_addr, address ame_addr,   bool is_vtable_stub,

                              int     index,    int     slop_bytes, int  index_dependent_slop) {

  const char* name        = is_vtable_stub ? "vtable" : "itable";

  const int   stub_length = code_size_limit(is_vtable_stub);

  if (log_is_enabled(Trace, vtablestubs)) {

    log_trace(vtablestubs)("%s #%d at " PTR_FORMAT ": size: %d, estimate: %d, slop area: %d",

                           name, index, p2i(s->code_begin()),

                           (int)(masm->pc() - s->code_begin()),

                           stub_length,

                           (int)(s->code_end() - masm->pc()));

  }

  guarantee(masm->pc() <= s->code_end(), "%s #%d: overflowed buffer, estimated len: %d, actual len: %d, overrun: %d",

                                         name, index, stub_length,

                                         (int)(masm->pc() - s->code_begin()),

                                         (int)(masm->pc() - s->code_end()));

  assert((masm->pc() + index_dependent_slop) <= s->code_end(), "%s #%d: spare space for 32-bit offset: required = %d, available = %d",

                                         name, index, index_dependent_slop,

                                         (int)(s->code_end() - masm->pc()));

  // After the first vtable/itable stub is generated, we have a much

  // better estimate for the stub size. Remember/update this

  // estimate after some sanity checks.

  check_and_set_size_limit(is_vtable_stub, masm->offset(), slop_bytes);

  s->set_exception_points(npe_addr, ame_addr);

}

address VtableStubs::find_stub(bool is_vtable_stub, int vtable_index) {

  assert(vtable_index >= 0, "must be positive");

  VtableStub* s;

  {

    MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);

    s = lookup(is_vtable_stub, vtable_index);

    if (s == NULL) {

      if (is_vtable_stub) {

        s = create_vtable_stub(vtable_index);

      } else {

        s = create_itable_stub(vtable_index);

      }

      // Creation of vtable or itable can fail if there is not enough free space in the code cache.

      if (s == NULL) {

        return NULL;

      }

      enter(is_vtable_stub, vtable_index, s);

      if (PrintAdapterHandlers) {

        tty->print_cr("Decoding VtableStub %s[%d]@" INTX_FORMAT,

                      is_vtable_stub? "vtbl": "itbl", vtable_index, p2i(VtableStub::receiver_location()));

        Disassembler::decode(s->code_begin(), s->code_end());

      }

      // Notify JVMTI about this stub. The event will be recorded by the enclosing

      // JvmtiDynamicCodeEventCollector and posted when this thread has released

      // all locks. Only post this event if a new state is not required. Creating a new state would

      // cause a safepoint and the caller of this code has a NoSafepointVerifier.

      if (JvmtiExport::should_post_dynamic_code_generated()) {

        JvmtiExport::post_dynamic_code_generated_while_holding_locks(is_vtable_stub? "vtable stub": "itable stub",

                                                                     s->code_begin(), s->code_end());

      }

    }

  }

  return s->entry_point();

}

inline uint VtableStubs::hash(bool is_vtable_stub, int vtable_index){

  // Assumption: receiver_location < 4 in most cases.

  int hash = ((vtable_index << 2) ^ VtableStub::receiver_location()->value()) + vtable_index;

  return (is_vtable_stub ? ~hash : hash)  & mask;

}

VtableStub* VtableStubs::lookup(bool is_vtable_stub, int vtable_index) {

  assert_lock_strong(VtableStubs_lock);

  unsigned hash = VtableStubs::hash(is_vtable_stub, vtable_index);

  VtableStub* s = _table[hash];

  while( s && !s->matches(is_vtable_stub, vtable_index)) s = s->next();

  return s;

}

void VtableStubs::enter(bool is_vtable_stub, int vtable_index, VtableStub* s) {

  assert_lock_strong(VtableStubs_lock);

  assert(s->matches(is_vtable_stub, vtable_index), "bad vtable stub");

  unsigned int h = VtableStubs::hash(is_vtable_stub, vtable_index);

  // enter s at the beginning of the corresponding list

  s->set_next(_table[h]);

  _table[h] = s;

  _number_of_vtable_stubs++;

}

VtableStub* VtableStubs::entry_point(address pc) {

  MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);

  VtableStub* stub = (VtableStub*)(pc - VtableStub::entry_offset());

  uint hash = VtableStubs::hash(stub->is_vtable_stub(), stub->index());

  VtableStub* s;

  for (s = _table[hash]; s != NULL && s != stub; s = s->next()) {}

  return (s == stub) ? s : NULL;

}

bool VtableStubs::contains(address pc) {

  // simple solution for now - we may want to use

  // a faster way if this function is called often

  return stub_containing(pc) != NULL;

}

VtableStub* VtableStubs::stub_containing(address pc) {

  // Note: No locking needed since any change to the data structure

  //       happens with an atomic store into it (we don't care about

  //       consistency with the _number_of_vtable_stubs counter).

  for (int i = 0; i < N; i++) {

    for (VtableStub* s = _table[i]; s != NULL; s = s->next()) {

      if (s->contains(pc)) return s;

    }

  }

  return NULL;

}

void vtableStubs_init() {

  VtableStubs::initialize();

}

void VtableStubs::vtable_stub_do(void f(VtableStub*)) {

    for (int i = 0; i < N; i++) {

        for (VtableStub* s = _table[i]; s != NULL; s = s->next()) {

            f(s);

        }

    }

}

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

// Non-product code

#ifndef PRODUCT

extern "C" void bad_compiled_vtable_index(JavaThread* thread, oop receiver, int index) {

  ResourceMark rm;

  HandleMark hm;

  Klass* klass = receiver->klass();

  InstanceKlass* ik = InstanceKlass::cast(klass);

  klassVtable vt = ik->vtable();

  ik->print();

  fatal("bad compiled vtable dispatch: receiver " INTPTR_FORMAT ", "

        "index %d (vtable length %d)",

        p2i(receiver), index, vt.length());

}

#endif // PRODUCT