/*

 * Copyright (c) 1997, 2017, 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

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 */

#include "precompiled.hpp"

#include "interpreter/oopMapCache.hpp"

#include "logging/log.hpp"

#include "logging/logStream.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/signature.hpp"

class OopMapCacheEntry: private InterpreterOopMap {

  friend class InterpreterOopMap;

  friend class OopMapForCacheEntry;

  friend class OopMapCache;

  friend class VerifyClosure;

 private:

  OopMapCacheEntry* _next;

 protected:

  // Initialization

  void fill(const methodHandle& method, int bci);

  // fills the bit mask for native calls

  void fill_for_native(const methodHandle& method);

  void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top);

  // Deallocate bit masks and initialize fields

  void flush();

 private:

  void allocate_bit_mask();   // allocates the bit mask on C heap f necessary

  void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary

  bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top);

 public:

  OopMapCacheEntry() : InterpreterOopMap() {

    _next = NULL;

#ifdef ASSERT

    _resource_allocate_bit_mask = false;

#endif

  }

};

// Implementation of OopMapForCacheEntry

// (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)

class OopMapForCacheEntry: public GenerateOopMap {

  OopMapCacheEntry *_entry;

  int               _bci;

  int               _stack_top;

  virtual bool report_results() const     { return false; }

  virtual bool possible_gc_point          (BytecodeStream *bcs);

  virtual void fill_stackmap_prolog       (int nof_gc_points);

  virtual void fill_stackmap_epilog       ();

  virtual void fill_stackmap_for_opcodes  (BytecodeStream *bcs,

                                           CellTypeState* vars,

                                           CellTypeState* stack,

                                           int stack_top);

  virtual void fill_init_vars             (GrowableArray<intptr_t> *init_vars);

 public:

  OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry);

  // Computes stack map for (method,bci) and initialize entry

  void compute_map(TRAPS);

  int  size();

};

OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {

  _bci       = bci;

  _entry     = entry;

  _stack_top = -1;

}

void OopMapForCacheEntry::compute_map(TRAPS) {

  assert(!method()->is_native(), "cannot compute oop map for native methods");

  // First check if it is a method where the stackmap is always empty

  if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {

    _entry->set_mask_size(0);

  } else {

    ResourceMark rm;

    GenerateOopMap::compute_map(CATCH);

    result_for_basicblock(_bci);

  }

}

bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {

  return false; // We are not reporting any result. We call result_for_basicblock directly

}

void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {

  // Do nothing

}

void OopMapForCacheEntry::fill_stackmap_epilog() {

  // Do nothing

}

void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {

  // Do nothing

}

void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,

                                                    CellTypeState* vars,

                                                    CellTypeState* stack,

                                                    int stack_top) {

  // Only interested in one specific bci

  if (bcs->bci() == _bci) {

    _entry->set_mask(vars, stack, stack_top);

    _stack_top = stack_top;

  }

}

int OopMapForCacheEntry::size() {

  assert(_stack_top != -1, "compute_map must be called first");

  return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;

}

// Implementation of InterpreterOopMap and OopMapCacheEntry

class VerifyClosure : public OffsetClosure {

 private:

  OopMapCacheEntry* _entry;

  bool              _failed;

 public:

  VerifyClosure(OopMapCacheEntry* entry)         { _entry = entry; _failed = false; }

  void offset_do(int offset)                     { if (!_entry->is_oop(offset)) _failed = true; }

  bool failed() const                            { return _failed; }

};

InterpreterOopMap::InterpreterOopMap() {

  initialize();

#ifdef ASSERT

  _resource_allocate_bit_mask = true;

#endif

}

InterpreterOopMap::~InterpreterOopMap() {

  // The expection is that the bit mask was allocated

  // last in this resource area.  That would make the free of the

  // bit_mask effective (see how FREE_RESOURCE_ARRAY does a free).

  // If it was not allocated last, there is not a correctness problem

  // but the space for the bit_mask is not freed.

  assert(_resource_allocate_bit_mask, "Trying to free C heap space");

  if (mask_size() > small_mask_limit) {

    FREE_RESOURCE_ARRAY(uintptr_t, _bit_mask[0], mask_word_size());

  }

}

bool InterpreterOopMap::is_empty() const {

  bool result = _method == NULL;

  assert(_method != NULL || (_bci == 0 &&

    (_mask_size == 0 || _mask_size == USHRT_MAX) &&

    _bit_mask[0] == 0), "Should be completely empty");

  return result;

}

void InterpreterOopMap::initialize() {

  _method    = NULL;

  _mask_size = USHRT_MAX;  // This value should cause a failure quickly

  _bci       = 0;

  _expression_stack_size = 0;

  for (int i = 0; i < N; i++) _bit_mask[i] = 0;

}

void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const {

  int n = number_of_entries();

  int word_index = 0;

  uintptr_t value = 0;

  uintptr_t mask = 0;

  // iterate over entries

  for (int i = 0; i < n; i++, mask <<= bits_per_entry) {

    // get current word

    if (mask == 0) {

      value = bit_mask()[word_index++];

      mask = 1;

    }

    // test for oop

    if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);

  }

}

void InterpreterOopMap::print() const {

  int n = number_of_entries();

  tty->print("oop map for ");

  method()->print_value();

  tty->print(" @ %d = [%d] { ", bci(), n);

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

    if (is_dead(i)) tty->print("%d+ ", i);

    else

    if (is_oop(i)) tty->print("%d ", i);

  }

  tty->print_cr("}");

}

class MaskFillerForNative: public NativeSignatureIterator {

 private:

  uintptr_t * _mask;                             // the bit mask to be filled

  int         _size;                             // the mask size in bits

  void set_one(int i) {

    i *= InterpreterOopMap::bits_per_entry;

    assert(0 <= i && i < _size, "offset out of bounds");

    _mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));

  }

 public:

  void pass_int()                                { /* ignore */ }

  void pass_long()                               { /* ignore */ }

  void pass_float()                              { /* ignore */ }

  void pass_double()                             { /* ignore */ }

  void pass_object()                             { set_one(offset()); }

  MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {

    _mask   = mask;

    _size   = size;

    // initialize with 0

    int i = (size + BitsPerWord - 1) / BitsPerWord;

    while (i-- > 0) _mask[i] = 0;

  }

  void generate() {

    NativeSignatureIterator::iterate();

  }

};

bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {

  // Check mask includes map

  VerifyClosure blk(this);

  iterate_oop(&blk);

  if (blk.failed()) return false;

  // Check if map is generated correctly

  // (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)

  Log(interpreter, oopmap) logv;

  LogStream st(logv.trace());

  st.print("Locals (%d): ", max_locals);

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

    bool v1 = is_oop(i)               ? true : false;

    bool v2 = vars[i].is_reference()  ? true : false;

    assert(v1 == v2, "locals oop mask generation error");

    st.print("%d", v1 ? 1 : 0);

  }

  st.cr();

  st.print("Stack (%d): ", stack_top);

  for(int j = 0; j < stack_top; j++) {

    bool v1 = is_oop(max_locals + j)  ? true : false;

    bool v2 = stack[j].is_reference() ? true : false;

    assert(v1 == v2, "stack oop mask generation error");

    st.print("%d", v1 ? 1 : 0);

  }

  st.cr();

  return true;

}

void OopMapCacheEntry::allocate_bit_mask() {

  if (mask_size() > small_mask_limit) {

    assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");

    _bit_mask[0] = (intptr_t)

      NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);

  }

}

void OopMapCacheEntry::deallocate_bit_mask() {

  if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {

    assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),

      "This bit mask should not be in the resource area");

    FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);

    debug_only(_bit_mask[0] = 0;)

  }

}

void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {

  assert(mh->is_native(), "method must be native method");

  set_mask_size(mh->size_of_parameters() * bits_per_entry);

  allocate_bit_mask();

  // fill mask for parameters

  MaskFillerForNative mf(mh, bit_mask(), mask_size());

  mf.generate();

}

void OopMapCacheEntry::fill(const methodHandle& method, int bci) {

  HandleMark hm;

  // Flush entry to deallocate an existing entry

  flush();

  set_method(method());

  set_bci(bci);

  if (method->is_native()) {

    // Native method activations have oops only among the parameters and one

    // extra oop following the parameters (the mirror for static native methods).

    fill_for_native(method);

  } else {

    EXCEPTION_MARK;

    OopMapForCacheEntry gen(method, bci, this);

    gen.compute_map(CATCH);

  }

}

void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {

  // compute bit mask size

  int max_locals = method()->max_locals();

  int n_entries = max_locals + stack_top;

  set_mask_size(n_entries * bits_per_entry);

  allocate_bit_mask();

  set_expression_stack_size(stack_top);

  // compute bits

  int word_index = 0;

  uintptr_t value = 0;

  uintptr_t mask = 1;

  CellTypeState* cell = vars;

  for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {

    // store last word

    if (mask == 0) {

      bit_mask()[word_index++] = value;

      value = 0;

      mask = 1;

    }

    // switch to stack when done with locals

    if (entry_index == max_locals) {

      cell = stack;

    }

    // set oop bit

    if ( cell->is_reference()) {

      value |= (mask << oop_bit_number );

    }

    // set dead bit

    if (!cell->is_live()) {

      value |= (mask << dead_bit_number);

      assert(!cell->is_reference(), "dead value marked as oop");

    }

  }

  // make sure last word is stored

  bit_mask()[word_index] = value;

  // verify bit mask

  assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");

}

void OopMapCacheEntry::flush() {

  deallocate_bit_mask();

  initialize();

}

// Implementation of OopMapCache

void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {

  assert(_resource_allocate_bit_mask,

    "Should not resource allocate the _bit_mask");

  set_method(from->method());

  set_bci(from->bci());

  set_mask_size(from->mask_size());

  set_expression_stack_size(from->expression_stack_size());

  // Is the bit mask contained in the entry?

  if (from->mask_size() <= small_mask_limit) {

    memcpy((void *)_bit_mask, (void *)from->_bit_mask,

      mask_word_size() * BytesPerWord);

  } else {

    // The expectation is that this InterpreterOopMap is a recently created

    // and empty. It is used to get a copy of a cached entry.

    // If the bit mask has a value, it should be in the

    // resource area.

    assert(_bit_mask[0] == 0 ||

      Thread::current()->resource_area()->contains((void*)_bit_mask[0]),

      "The bit mask should have been allocated from a resource area");

    // Allocate the bit_mask from a Resource area for performance.  Allocating

    // from the C heap as is done for OopMapCache has a significant

    // performance impact.

    _bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());

    assert(_bit_mask[0] != 0, "bit mask was not allocated");

    memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],

      mask_word_size() * BytesPerWord);

  }

}

inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {

  // We use method->code_size() rather than method->identity_hash() below since

  // the mark may not be present if a pointer to the method is already reversed.

  return   ((unsigned int) bci)

         ^ ((unsigned int) method->max_locals()         << 2)

         ^ ((unsigned int) method->code_size()          << 4)

         ^ ((unsigned int) method->size_of_parameters() << 6);

}

OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;

OopMapCache::OopMapCache() {

  _array  = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);

  for(int i = 0; i < _size; i++) _array[i] = NULL;

}

OopMapCache::~OopMapCache() {

  assert(_array != NULL, "sanity check");

  // Deallocate oop maps that are allocated out-of-line

  flush();

  // Deallocate array

  FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);

}

OopMapCacheEntry* OopMapCache::entry_at(int i) const {

  return OrderAccess::load_acquire(&(_array[i % _size]));

}

bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {

  return Atomic::cmpxchg(entry, &_array[i % _size], old) == old;

}

void OopMapCache::flush() {

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

    OopMapCacheEntry* entry = _array[i];

    if (entry != NULL) {

      _array[i] = NULL;  // no barrier, only called in OopMapCache destructor

      entry->flush();

      FREE_C_HEAP_OBJ(entry);

    }

  }

}

void OopMapCache::flush_obsolete_entries() {

  assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");

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

    OopMapCacheEntry* entry = _array[i];

    if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {

      // Cache entry is occupied by an old redefined method and we don't want

      // to pin it down so flush the entry.

      if (log_is_enabled(Debug, redefine, class, oopmap)) {

        ResourceMark rm;

        log_debug(redefine, class, interpreter, oopmap)

          ("flush: %s(%s): cached entry @%d",

           entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);

      }

      _array[i] = NULL;

      entry->flush();

      FREE_C_HEAP_OBJ(entry);

    }

  }

}

// Called by GC for thread root scan during a safepoint only.  The other interpreted frame oopmaps

// are generated locally and not cached.

void OopMapCache::lookup(const methodHandle& method,

                         int bci,

                         InterpreterOopMap* entry_for) {

  assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");

  int probe = hash_value_for(method, bci);

  int i;

  OopMapCacheEntry* entry = NULL;

  if (log_is_enabled(Debug, interpreter, oopmap)) {

    static int count = 0;

    ResourceMark rm;

    log_debug(interpreter, oopmap)

          ("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,

           method()->name_and_sig_as_C_string(), probe);

  }

  // Search hashtable for match

  for(i = 0; i < _probe_depth; i++) {

    entry = entry_at(probe + i);

    if (entry != NULL && !entry->is_empty() && entry->match(method, bci)) {

      entry_for->resource_copy(entry);

      assert(!entry_for->is_empty(), "A non-empty oop map should be returned");

      log_debug(interpreter, oopmap)("- found at hash %d", probe + i);

      return;

    }

  }