text: /*
   * Copyright (c) 1997, 2020, 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/klass.inline.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"
  #include "utilities/powerOfTwo.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(int(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;
    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
  