/*

 * Copyright (c) 2005, 2015, 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 "ci/bcEscapeAnalyzer.hpp"

#include "ci/ciConstant.hpp"

#include "ci/ciField.hpp"

#include "ci/ciMethodBlocks.hpp"

#include "ci/ciStreams.hpp"

#include "interpreter/bytecode.hpp"

#include "oops/oop.inline.hpp"

#include "utilities/bitMap.inline.hpp"

#ifndef PRODUCT

  #define TRACE_BCEA(level, code)                                            \

    if (EstimateArgEscape && BCEATraceLevel >= level) {                        \

      code;                                                                  \

    }

#else

  #define TRACE_BCEA(level, code)

#endif

// Maintain a map of which arguments a local variable or

// stack slot may contain.  In addition to tracking

// arguments, it tracks two special values, "allocated"

// which represents any object allocated in the current

// method, and "unknown" which is any other object.

// Up to 30 arguments are handled, with the last one

// representing summary information for any extra arguments

class BCEscapeAnalyzer::ArgumentMap {

  uint  _bits;

  enum {MAXBIT = 29,

        ALLOCATED = 1,

        UNKNOWN = 2};

  uint int_to_bit(uint e) const {

    if (e > MAXBIT)

      e = MAXBIT;

    return (1 << (e + 2));

  }

public:

  ArgumentMap()                         { _bits = 0;}

  void set_bits(uint bits)              { _bits = bits;}

  uint get_bits() const                 { return _bits;}

  void clear()                          { _bits = 0;}

  void set_all()                        { _bits = ~0u; }

  bool is_empty() const                 { return _bits == 0; }

  bool contains(uint var) const         { return (_bits & int_to_bit(var)) != 0; }

  bool is_singleton(uint var) const     { return (_bits == int_to_bit(var)); }

  bool contains_unknown() const         { return (_bits & UNKNOWN) != 0; }

  bool contains_allocated() const       { return (_bits & ALLOCATED) != 0; }

  bool contains_vars() const            { return (_bits & (((1 << MAXBIT) -1) << 2)) != 0; }

  void set(uint var)                    { _bits = int_to_bit(var); }

  void add(uint var)                    { _bits |= int_to_bit(var); }

  void add_unknown()                    { _bits = UNKNOWN; }

  void add_allocated()                  { _bits = ALLOCATED; }

  void set_union(const ArgumentMap &am)     { _bits |= am._bits; }

  void set_intersect(const ArgumentMap &am) { _bits |= am._bits; }

  void set_difference(const ArgumentMap &am) { _bits &=  ~am._bits; }

  void operator=(const ArgumentMap &am) { _bits = am._bits; }

  bool operator==(const ArgumentMap &am) { return _bits == am._bits; }

  bool operator!=(const ArgumentMap &am) { return _bits != am._bits; }

};

class BCEscapeAnalyzer::StateInfo {

public:

  ArgumentMap *_vars;

  ArgumentMap *_stack;

  int _stack_height;

  int _max_stack;

  bool _initialized;

  ArgumentMap empty_map;

  StateInfo() {

    empty_map.clear();

  }

  ArgumentMap raw_pop()  { guarantee(_stack_height > 0, "stack underflow"); return _stack[--_stack_height]; }

  ArgumentMap  apop()    { return raw_pop(); }

  void spop()            { raw_pop(); }

  void lpop()            { spop(); spop(); }

  void raw_push(ArgumentMap i)   { guarantee(_stack_height < _max_stack, "stack overflow"); _stack[_stack_height++] = i; }

  void apush(ArgumentMap i)      { raw_push(i); }

  void spush()           { raw_push(empty_map); }

  void lpush()           { spush(); spush(); }

};

void BCEscapeAnalyzer::set_returned(ArgumentMap vars) {

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

    if (vars.contains(i))

      _arg_returned.set(i);

  }

  _return_local = _return_local && !(vars.contains_unknown() || vars.contains_allocated());

  _return_allocated = _return_allocated && vars.contains_allocated() && !(vars.contains_unknown() || vars.contains_vars());

}

// return true if any element of vars is an argument

bool BCEscapeAnalyzer::is_argument(ArgumentMap vars) {

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

    if (vars.contains(i))

      return true;

  }

  return false;

}

// return true if any element of vars is an arg_stack argument

bool BCEscapeAnalyzer::is_arg_stack(ArgumentMap vars){

  if (_conservative)

    return true;

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

    if (vars.contains(i) && _arg_stack.test(i))

      return true;

  }

  return false;

}

// return true if all argument elements of vars are returned

bool BCEscapeAnalyzer::returns_all(ArgumentMap vars) {

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

    if (vars.contains(i) && !_arg_returned.test(i)) {

      return false;

    }

  }

  return true;

}

void BCEscapeAnalyzer::clear_bits(ArgumentMap vars, VectorSet &bm) {

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

    if (vars.contains(i)) {

      bm >>= i;

    }

  }

}

void BCEscapeAnalyzer::set_method_escape(ArgumentMap vars) {

  clear_bits(vars, _arg_local);

  if (vars.contains_allocated()) {

    _allocated_escapes = true;

  }

}

void BCEscapeAnalyzer::set_global_escape(ArgumentMap vars, bool merge) {

  clear_bits(vars, _arg_local);

  clear_bits(vars, _arg_stack);

  if (vars.contains_allocated())

    _allocated_escapes = true;

  if (merge && !vars.is_empty()) {

    // Merge new state into already processed block.

    // New state is not taken into account and

    // it may invalidate set_returned() result.

    if (vars.contains_unknown() || vars.contains_allocated()) {

      _return_local = false;

    }

    if (vars.contains_unknown() || vars.contains_vars()) {

      _return_allocated = false;

    }

    if (_return_local && vars.contains_vars() && !returns_all(vars)) {

      // Return result should be invalidated if args in new

      // state are not recorded in return state.

      _return_local = false;

    }

  }

}

void BCEscapeAnalyzer::set_dirty(ArgumentMap vars) {

  clear_bits(vars, _dirty);

}

void BCEscapeAnalyzer::set_modified(ArgumentMap vars, int offs, int size) {

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

    if (vars.contains(i)) {

      set_arg_modified(i, offs, size);

    }

  }

  if (vars.contains_unknown())

    _unknown_modified = true;

}

bool BCEscapeAnalyzer::is_recursive_call(ciMethod* callee) {

  for (BCEscapeAnalyzer* scope = this; scope != NULL; scope = scope->_parent) {

    if (scope->method() == callee) {

      return true;

    }

  }

  return false;

}

bool BCEscapeAnalyzer::is_arg_modified(int arg, int offset, int size_in_bytes) {

  if (offset == OFFSET_ANY)

    return _arg_modified[arg] != 0;

  assert(arg >= 0 && arg < _arg_size, "must be an argument.");

  bool modified = false;

  int l = offset / HeapWordSize;

  if (l > ARG_OFFSET_MAX)

    l = ARG_OFFSET_MAX;

  if (h > ARG_OFFSET_MAX+1)

    h = ARG_OFFSET_MAX + 1;

  for (int i = l; i < h; i++) {

    modified = modified || (_arg_modified[arg] & (1 << i)) != 0;

  }

  return modified;

}

void BCEscapeAnalyzer::set_arg_modified(int arg, int offset, int size_in_bytes) {

  if (offset == OFFSET_ANY) {

    _arg_modified[arg] =  (uint) -1;

    return;

  }

  assert(arg >= 0 && arg < _arg_size, "must be an argument.");

  int l = offset / HeapWordSize;

  if (l > ARG_OFFSET_MAX)

    l = ARG_OFFSET_MAX;

  if (h > ARG_OFFSET_MAX+1)

    h = ARG_OFFSET_MAX + 1;

  for (int i = l; i < h; i++) {

    _arg_modified[arg] |= (1 << i);

  }

}

void BCEscapeAnalyzer::invoke(StateInfo &state, Bytecodes::Code code, ciMethod* target, ciKlass* holder) {

  int i;

  // retrieve information about the callee

  ciInstanceKlass* klass = target->holder();

  ciInstanceKlass* calling_klass = method()->holder();

  ciInstanceKlass* callee_holder = ciEnv::get_instance_klass_for_declared_method_holder(holder);

  ciInstanceKlass* actual_recv = callee_holder;

  // Some methods are obviously bindable without any type checks so

  // convert them directly to an invokespecial or invokestatic.

  if (target->is_loaded() && !target->is_abstract() && target->can_be_statically_bound()) {

    switch (code) {

    case Bytecodes::_invokevirtual:

      code = Bytecodes::_invokespecial;

      break;

    case Bytecodes::_invokehandle:

      code = target->is_static() ? Bytecodes::_invokestatic : Bytecodes::_invokespecial;

      break;

    }

  }

  // compute size of arguments

  int arg_size = target->invoke_arg_size(code);

  int arg_base = MAX2(state._stack_height - arg_size, 0);

  // direct recursive calls are skipped if they can be bound statically without introducing

  // dependencies and if parameters are passed at the same position as in the current method

  // other calls are skipped if there are no unescaped arguments passed to them

  bool directly_recursive = (method() == target) &&

               (code != Bytecodes::_invokevirtual || target->is_final_method() || state._stack[arg_base] .is_empty());

  // check if analysis of callee can safely be skipped

  bool skip_callee = true;

  for (i = state._stack_height - 1; i >= arg_base && skip_callee; i--) {

    ArgumentMap arg = state._stack[i];

    skip_callee = !is_argument(arg) || !is_arg_stack(arg) || (directly_recursive && arg.is_singleton(i - arg_base));

  }

  // For now we conservatively skip invokedynamic.

  if (code == Bytecodes::_invokedynamic) {

    skip_callee = true;

  }

  if (skip_callee) {

    TRACE_BCEA(3, tty->print_cr("[EA] skipping method %s::%s", holder->name()->as_utf8(), target->name()->as_utf8()));

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

      set_method_escape(state.raw_pop());

    }

    _unknown_modified = true;  // assume the worst since we don't analyze the called method

    return;

  }

  // determine actual method (use CHA if necessary)

  ciMethod* inline_target = NULL;

  if (target->is_loaded() && klass->is_loaded()

      && (klass->is_initialized() || klass->is_interface() && target->holder()->is_initialized())

      && target->is_loaded()) {

    if (code == Bytecodes::_invokestatic

        || code == Bytecodes::_invokespecial

        || code == Bytecodes::_invokevirtual && target->is_final_method()) {

      inline_target = target;

    } else {

      inline_target = target->find_monomorphic_target(calling_klass, callee_holder, actual_recv);

    }

  }

  if (inline_target != NULL && !is_recursive_call(inline_target)) {

    // analyze callee

    BCEscapeAnalyzer analyzer(inline_target, this);

    // adjust escape state of actual parameters

    bool must_record_dependencies = false;

    for (i = arg_size - 1; i >= 0; i--) {

      ArgumentMap arg = state.raw_pop();

      // Check if callee arg is a caller arg or an allocated object

      bool allocated = arg.contains_allocated();

      if (!(is_argument(arg) || allocated))

        continue;

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

        if (arg.contains(j)) {

          _arg_modified[j] |= analyzer._arg_modified[i];

        }

      }

      if (!(is_arg_stack(arg) || allocated)) {

        // arguments have already been recognized as escaping

      } else if (analyzer.is_arg_stack(i) && !analyzer.is_arg_returned(i)) {

        set_method_escape(arg);

        must_record_dependencies = true;

      } else {

        set_global_escape(arg);

      }

    }

    _unknown_modified = _unknown_modified || analyzer.has_non_arg_side_affects();

    // record dependencies if at least one parameter retained stack-allocatable

    if (must_record_dependencies) {

      if (code == Bytecodes::_invokeinterface || code == Bytecodes::_invokevirtual && !target->is_final_method()) {

        _dependencies.append(actual_recv);

        _dependencies.append(inline_target);

      }

      _dependencies.appendAll(analyzer.dependencies());

    }

  } else {

    TRACE_BCEA(1, tty->print_cr("[EA] virtual method %s is not monomorphic.",

                                target->name()->as_utf8()));

    // conservatively mark all actual parameters as escaping globally

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

      ArgumentMap arg = state.raw_pop();

      if (!is_argument(arg))

        continue;

      set_modified(arg, OFFSET_ANY, type2size[T_INT]*HeapWordSize);

      set_global_escape(arg);

    }

    _unknown_modified = true;  // assume the worst since we don't know the called method

  }

}

bool BCEscapeAnalyzer::contains(uint arg_set1, uint arg_set2) {

  return ((~arg_set1) | arg_set2) == 0;

}

void BCEscapeAnalyzer::iterate_one_block(ciBlock *blk, StateInfo &state, GrowableArray<ciBlock *> &successors) {

  blk->set_processed();

  ciBytecodeStream s(method());

  int limit_bci = blk->limit_bci();

  bool fall_through = false;

  ArgumentMap allocated_obj;

  allocated_obj.add_allocated();

  ArgumentMap unknown_obj;

  unknown_obj.add_unknown();

  ArgumentMap empty_map;

  s.reset_to_bci(blk->start_bci());

  while (s.next() != ciBytecodeStream::EOBC() && s.cur_bci() < limit_bci) {

    fall_through = true;

    switch (s.cur_bc()) {

      case Bytecodes::_nop:

        break;

      case Bytecodes::_aconst_null:

        state.apush(unknown_obj);

        break;

      case Bytecodes::_iconst_m1:

      case Bytecodes::_iconst_0:

      case Bytecodes::_iconst_1:

      case Bytecodes::_iconst_2:

      case Bytecodes::_iconst_3:

      case Bytecodes::_iconst_4:

      case Bytecodes::_iconst_5:

      case Bytecodes::_fconst_0:

      case Bytecodes::_fconst_1:

      case Bytecodes::_fconst_2:

      case Bytecodes::_bipush:

      case Bytecodes::_sipush:

        state.spush();

        break;

      case Bytecodes::_lconst_0:

      case Bytecodes::_lconst_1:

      case Bytecodes::_dconst_0:

      case Bytecodes::_dconst_1:

        state.lpush();

        break;

      case Bytecodes::_ldc:

      case Bytecodes::_ldc_w:

      case Bytecodes::_ldc2_w:

      {

        // Avoid calling get_constant() which will try to allocate

        // unloaded constant. We need only constant's type.

        int index = s.get_constant_pool_index();

        constantTag tag = s.get_constant_pool_tag(index);

        if (tag.is_long() || tag.is_double()) {

          // Only longs and doubles use 2 stack slots.

          state.lpush();

        } else if (tag.basic_type() == T_OBJECT) {

          state.apush(unknown_obj);

        } else {

          state.spush();

        }

        break;

      }

      case Bytecodes::_aload:

        state.apush(state._vars[s.get_index()]);

        break;

      case Bytecodes::_iload:

      case Bytecodes::_fload:

      case Bytecodes::_iload_0:

      case Bytecodes::_iload_1:

      case Bytecodes::_iload_2:

      case Bytecodes::_iload_3:

      case Bytecodes::_fload_0:

      case Bytecodes::_fload_1:

      case Bytecodes::_fload_2:

      case Bytecodes::_fload_3:

        state.spush();

        break;

      case Bytecodes::_lload:

      case Bytecodes::_dload:

      case Bytecodes::_lload_0:

      case Bytecodes::_lload_1:

      case Bytecodes::_lload_2:

      case Bytecodes::_lload_3:

      case Bytecodes::_dload_0:

      case Bytecodes::_dload_1:

      case Bytecodes::_dload_2:

      case Bytecodes::_dload_3:

        state.lpush();

        break;

      case Bytecodes::_aload_0:

        state.apush(state._vars[0]);

        break;

      case Bytecodes::_aload_1:

        state.apush(state._vars[1]);

        break;

      case Bytecodes::_aload_2:

        state.apush(state._vars[2]);

        break;

      case Bytecodes::_aload_3:

        state.apush(state._vars[3]);

        break;

      case Bytecodes::_iaload:

      case Bytecodes::_faload:

      case Bytecodes::_baload:

      case Bytecodes::_caload:

      case Bytecodes::_saload:

        state.spop();

        set_method_escape(state.apop());

        state.spush();

        break;

      case Bytecodes::_laload:

      case Bytecodes::_daload:

        state.spop();

        set_method_escape(state.apop());

        state.lpush();

        break;

      case Bytecodes::_aaload:

        { state.spop();

          ArgumentMap array = state.apop();

          set_method_escape(array);

          state.apush(unknown_obj);

          set_dirty(array);

        }

        break;

      case Bytecodes::_istore:

      case Bytecodes::_fstore:

      case Bytecodes::_istore_0:

      case Bytecodes::_istore_1:

      case Bytecodes::_istore_2:

      case Bytecodes::_istore_3:

      case Bytecodes::_fstore_0:

      case Bytecodes::_fstore_1:

      case Bytecodes::_fstore_2:

      case Bytecodes::_fstore_3:

        state.spop();

        break;

      case Bytecodes::_lstore:

      case Bytecodes::_dstore:

      case Bytecodes::_lstore_0:

      case Bytecodes::_lstore_1:

      case Bytecodes::_lstore_2:

      case Bytecodes::_lstore_3:

      case Bytecodes::_dstore_0:

      case Bytecodes::_dstore_1:

      case Bytecodes::_dstore_2:

      case Bytecodes::_dstore_3:

        state.lpop();