/*

 * Copyright (c) 2006, 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

 * questions.

 *

 */

#include "precompiled.hpp"

#include "ci/ciMethodBlocks.hpp"

#include "ci/ciStreams.hpp"

#include "interpreter/bytecode.hpp"

#include "utilities/copy.hpp"

// ciMethodBlocks

ciBlock *ciMethodBlocks::block_containing(int bci) {

  ciBlock *blk = _bci_to_block[bci];

  return blk;

}

bool ciMethodBlocks::is_block_start(int bci) {

  assert(bci >=0 && bci < _code_size, "valid bytecode range");

  ciBlock *b = _bci_to_block[bci];

  assert(b != NULL, "must have block for bytecode");

  return b->start_bci() == bci;

}

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

// ciMethodBlocks::split_block_at

//

// Split the block spanning bci into two separate ranges.  The former

// block becomes the second half and a new range is created for the

// first half.  Returns the range beginning at bci.

ciBlock *ciMethodBlocks::split_block_at(int bci) {

  ciBlock *former_block = block_containing(bci);

  ciBlock *new_block = new(_arena) ciBlock(_method, _num_blocks++, former_block->start_bci());

  _blocks->append(new_block);

  assert(former_block != NULL, "must not be NULL");

  new_block->set_limit_bci(bci);

  former_block->set_start_bci(bci);

  for (int pos=bci-1; pos >= 0; pos--) {

    ciBlock *current_block = block_containing(pos);

    if (current_block == former_block) {

      // Replace it.

      _bci_to_block[pos] = new_block;

    } else if (current_block == NULL) {

      // Non-bytecode start.  Skip.

      continue;

    } else {

      // We are done with our backwards walk

      break;

    }

  }

  // Move an exception handler information if needed.

  if (former_block->is_handler()) {

    int ex_start = former_block->ex_start_bci();

    int ex_end = former_block->ex_limit_bci();

    new_block->set_exception_range(ex_start, ex_end);

    // Clear information in former_block.

    former_block->clear_exception_handler();

  }

  return former_block;

}

ciBlock *ciMethodBlocks::make_block_at(int bci) {

  ciBlock *cb = block_containing(bci);

  if (cb == NULL ) {

    // This is our first time visiting this bytecode.  Create

    // a fresh block and assign it this starting point.

    ciBlock *nb = new(_arena) ciBlock(_method, _num_blocks++, bci);

    _blocks->append(nb);

     _bci_to_block[bci] = nb;

    return nb;

  } else if (cb->start_bci() == bci) {

    // The block begins at bci.  Simply return it.

    return cb;

  } else {

    // We have already created a block containing bci but

    // not starting at bci.  This existing block needs to

    // be split into two.

    return split_block_at(bci);

  }

}

ciBlock *ciMethodBlocks::make_dummy_block() {

  ciBlock *dum = new(_arena) ciBlock(_method, -1, 0);

  return dum;

}

void ciMethodBlocks::do_analysis() {

  ciBytecodeStream s(_method);

  ciBlock *cur_block = block_containing(0);

  int limit_bci = _method->code_size();

  while (s.next() != ciBytecodeStream::EOBC()) {

    int bci = s.cur_bci();

    // Determine if a new block has been made at the current bci.  If

    // this block differs from our current range, switch to the new

    // one and end the old one.

    assert(cur_block != NULL, "must always have a current block");

    ciBlock *new_block = block_containing(bci);

    if (new_block == NULL || new_block == cur_block) {

      // We have not marked this bci as the start of a new block.

      // Keep interpreting the current_range.

      _bci_to_block[bci] = cur_block;

    } else {

      cur_block->set_limit_bci(bci);

      cur_block = new_block;

    }

    switch (s.cur_bc()) {

      case Bytecodes::_ifeq        :

      case Bytecodes::_ifne        :

      case Bytecodes::_iflt        :

      case Bytecodes::_ifge        :

      case Bytecodes::_ifgt        :

      case Bytecodes::_ifle        :

      case Bytecodes::_if_icmpeq   :

      case Bytecodes::_if_icmpne   :

      case Bytecodes::_if_icmplt   :

      case Bytecodes::_if_icmpge   :

      case Bytecodes::_if_icmpgt   :

      case Bytecodes::_if_icmple   :

      case Bytecodes::_if_acmpeq   :

      case Bytecodes::_if_acmpne   :

      case Bytecodes::_ifnull      :

      case Bytecodes::_ifnonnull   :

      {

        cur_block->set_control_bci(bci);

        ciBlock *fall_through = make_block_at(s.next_bci());

        int dest_bci = s.get_dest();

        ciBlock *dest = make_block_at(dest_bci);

        break;

      }

      case Bytecodes::_goto        :

      {

        cur_block->set_control_bci(bci);

        if (s.next_bci() < limit_bci) {

          (void) make_block_at(s.next_bci());

        }

        int dest_bci = s.get_dest();

        ciBlock *dest = make_block_at(dest_bci);

        break;

      }

      case Bytecodes::_jsr         :

      {

        cur_block->set_control_bci(bci);

        ciBlock *ret = make_block_at(s.next_bci());

        int dest_bci = s.get_dest();

        ciBlock *dest = make_block_at(dest_bci);

        break;

      }

      case Bytecodes::_tableswitch :

        {

          cur_block->set_control_bci(bci);

          Bytecode_tableswitch sw(&s);

          int len = sw.length();

          ciBlock *dest;

          int dest_bci;

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

            dest_bci = s.cur_bci() + sw.dest_offset_at(i);

            dest = make_block_at(dest_bci);

          }

          dest_bci = s.cur_bci() + sw.default_offset();

          make_block_at(dest_bci);

          if (s.next_bci() < limit_bci) {

            dest = make_block_at(s.next_bci());

          }

        }

        break;

      case Bytecodes::_lookupswitch:

        {

          cur_block->set_control_bci(bci);

          Bytecode_lookupswitch sw(&s);

          int len = sw.number_of_pairs();

          ciBlock *dest;

          int dest_bci;

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

            dest_bci = s.cur_bci() + sw.pair_at(i).offset();

            dest = make_block_at(dest_bci);

          }

          dest_bci = s.cur_bci() + sw.default_offset();

          dest = make_block_at(dest_bci);

          if (s.next_bci() < limit_bci) {

            dest = make_block_at(s.next_bci());

          }

        }

        break;

      case Bytecodes::_goto_w      :

      {

        cur_block->set_control_bci(bci);

        if (s.next_bci() < limit_bci) {

          (void) make_block_at(s.next_bci());

        }

        int dest_bci = s.get_far_dest();

        ciBlock *dest = make_block_at(dest_bci);

        break;

      }

      case Bytecodes::_jsr_w       :

      {

        cur_block->set_control_bci(bci);

        ciBlock *ret = make_block_at(s.next_bci());

        int dest_bci = s.get_far_dest();

        ciBlock *dest = make_block_at(dest_bci);

        break;

      }

      case Bytecodes::_athrow      :

        cur_block->set_may_throw();

        // fall-through

      case Bytecodes::_ret         :

      case Bytecodes::_ireturn     :

      case Bytecodes::_lreturn     :

      case Bytecodes::_freturn     :

      case Bytecodes::_dreturn     :

      case Bytecodes::_areturn     :

      case Bytecodes::_return      :

        cur_block->set_control_bci(bci);

        if (s.next_bci() < limit_bci) {

          (void) make_block_at(s.next_bci());

        }

        break;

      default:

        break;

    }

  }

  //  End the last block

  cur_block->set_limit_bci(limit_bci);

}

ciMethodBlocks::ciMethodBlocks(Arena *arena, ciMethod *meth): _method(meth),

                          _arena(arena), _num_blocks(0), _code_size(meth->code_size()) {

  int block_estimate = _code_size / 8;

  _blocks =  new(_arena) GrowableArray<ciBlock *>(_arena, block_estimate, 0, NULL);

  int b2bsize = _code_size * sizeof(ciBlock **);

  _bci_to_block = (ciBlock **) arena->Amalloc(b2bsize);

  Copy::zero_to_words((HeapWord*) _bci_to_block, b2bsize / sizeof(HeapWord));

  // create initial block covering the entire method

  ciBlock *b = new(arena) ciBlock(_method, _num_blocks++, 0);

  _blocks->append(b);

  _bci_to_block[0] = b;

  // create blocks for exception handlers

  if (meth->has_exception_handlers()) {

    for(ciExceptionHandlerStream str(meth); !str.is_done(); str.next()) {

      ciExceptionHandler* handler = str.handler();

      ciBlock *eb = make_block_at(handler->handler_bci());

      //

      // Several exception handlers can have the same handler_bci:

      //

      //  try {

      //    if (a.foo(b) < 0) {

      //      return a.error();

      //    }

      //    return CoderResult.UNDERFLOW;

      //  } finally {

      //      a.position(b);

      //  }

      //

      //  The try block above is divided into 2 exception blocks

      //  separated by 'areturn' bci.

      //

      int ex_start = handler->start();

      int ex_end = handler->limit();

      // ensure a block at the start of exception range and start of following code

      (void) make_block_at(ex_start);

      if (ex_end < _code_size)

        (void) make_block_at(ex_end);

      if (eb->is_handler()) {

        // Extend old handler exception range to cover additional range.

        int old_ex_start = eb->ex_start_bci();

        int old_ex_end   = eb->ex_limit_bci();

        if (ex_start > old_ex_start)

          ex_start = old_ex_start;

        if (ex_end < old_ex_end)

          ex_end = old_ex_end;

        eb->clear_exception_handler(); // Reset exception information

      }

      eb->set_exception_range(ex_start, ex_end);

    }

  }

  // scan the bytecodes and identify blocks

  do_analysis();

  // mark blocks that have exception handlers

  if (meth->has_exception_handlers()) {

    for(ciExceptionHandlerStream str(meth); !str.is_done(); str.next()) {

      ciExceptionHandler* handler = str.handler();

      int ex_start = handler->start();

      int ex_end = handler->limit();

      int bci = ex_start;

      while (bci < ex_end) {

        ciBlock *b = block_containing(bci);

        b->set_has_handler();

        bci = b->limit_bci();

      }

    }

  }

}

void ciMethodBlocks::clear_processed() {

  for (int i = 0; i < _blocks->length(); i++)

    _blocks->at(i)->clear_processed();

}

#ifndef PRODUCT

void ciMethodBlocks::dump() {

  tty->print("---- blocks for method: ");

  _method->print();

  tty->cr();

  for (int i = 0; i < _blocks->length(); i++) {

    tty->print("  B%d: ", i); _blocks->at(i)->dump();

  }

}

#endif

ciBlock::ciBlock(ciMethod *method, int index, int start_bci) :

                         _idx(index), _start_bci(start_bci), _limit_bci(-1), _control_bci(fall_through_bci),

                         _flags(0), _ex_start_bci(-1), _ex_limit_bci(-1)

#ifndef PRODUCT

                         , _method(method)

#endif

{

}

void ciBlock::set_exception_range(int start_bci, int limit_bci)  {

   assert(limit_bci >= start_bci, "valid range");

   assert(!is_handler() && _ex_start_bci == -1 && _ex_limit_bci == -1, "must not be handler");

   _ex_start_bci = start_bci;

   _ex_limit_bci = limit_bci;

   set_handler();

}

#ifndef PRODUCT

static const char *flagnames[] = {

  "Processed",

  "Handler",

  "MayThrow",

  "Jsr",

  "Ret",

  "RetTarget",

  "HasHandler",

};

void ciBlock::dump() {

  tty->print(" [%d .. %d), {", _start_bci, _limit_bci);

  for (int i = 0; i < 7; i++) {

    if ((_flags & (1 << i)) != 0) {

      tty->print(" %s", flagnames[i]);

    }

  }

  tty->print(" ]");

  if (is_handler())

    tty->print(" handles(%d..%d)", _ex_start_bci, _ex_limit_bci);

  tty->cr();

}

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

// ciBlock::print_on

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

  st->print_cr("--------------------------------------------------------");

  st->print   ("ciBlock [%d - %d) control : ", start_bci(), limit_bci());

  if (control_bci() == fall_through_bci) {

    st->print_cr("%d:fall through", limit_bci());

  } else {

    st->print_cr("%d:%s", control_bci(),

        Bytecodes::name(method()->java_code_at_bci(control_bci())));

  }

  if (Verbose || WizardMode) {

    method()->print_codes_on(start_bci(), limit_bci(), st);

  }

}

#endif