/*

 * Copyright (c) 1997, 2013, 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 "memory/allocation.inline.hpp"

#include "opto/callnode.hpp"

#include "opto/chaitin.hpp"

#include "opto/live.hpp"

#include "opto/machnode.hpp"

// Compute live-in/live-out.  We use a totally incremental algorithm.  The LIVE

// problem is monotonic.  The steady-state solution looks like this: pull a

// block from the worklist.  It has a set of delta's - values which are newly

// live-in from the block.  Push these to the live-out sets of all predecessor

// blocks.  At each predecessor, the new live-out values are ANDed with what is

// already live-out (extra stuff is added to the live-out sets).  Then the

// remaining new live-out values are ANDed with what is locally defined.

// Leftover bits become the new live-in for the predecessor block, and the pred

// block is put on the worklist.

//   The locally live-in stuff is computed once and added to predecessor

// live-out sets.  This separate compilation is done in the outer loop below.

PhaseLive::PhaseLive( const PhaseCFG &cfg, const LRG_List &names, Arena *arena ) : Phase(LIVE), _cfg(cfg), _names(names), _arena(arena), _live(0) {

}

void PhaseLive::compute(uint maxlrg) {

  _maxlrg   = maxlrg;

  _worklist = new (_arena) Block_List();

  // Init the sparse live arrays.  This data is live on exit from here!

  // The _live info is the live-out info.

  _live = (IndexSet*)_arena->Amalloc(sizeof(IndexSet) * _cfg.number_of_blocks());

  uint i;

  for (i = 0; i < _cfg.number_of_blocks(); i++) {

    _live[i].initialize(_maxlrg);

  }

  // Init the sparse arrays for delta-sets.

  ResourceMark rm;              // Nuke temp storage on exit

  // Does the memory used by _defs and _deltas get reclaimed?  Does it matter?  TT

  // Array of values defined locally in blocks

  _defs = NEW_RESOURCE_ARRAY(IndexSet,_cfg.number_of_blocks());

  for (i = 0; i < _cfg.number_of_blocks(); i++) {

    _defs[i].initialize(_maxlrg);

  }

  // Array of delta-set pointers, indexed by block pre_order-1.

  _deltas = NEW_RESOURCE_ARRAY(IndexSet*,_cfg.number_of_blocks());

  memset( _deltas, 0, sizeof(IndexSet*)* _cfg.number_of_blocks());

  _free_IndexSet = NULL;

  // Blocks having done pass-1

  VectorSet first_pass(Thread::current()->resource_area());

  // Outer loop: must compute local live-in sets and push into predecessors.

  for (uint j = _cfg.number_of_blocks(); j > 0; j--) {

    Block* block = _cfg.get_block(j - 1);

    // Compute the local live-in set.  Start with any new live-out bits.

    IndexSet* use = getset(block);

    IndexSet* def = &_defs[block->_pre_order-1];

    DEBUG_ONLY(IndexSet *def_outside = getfreeset();)

    uint i;

    for (i = block->number_of_nodes(); i > 1; i--) {

      Node* n = block->get_node(i-1);

      if (n->is_Phi()) {

        break;

      }

      uint r = _names.at(n->_idx);

      assert(!def_outside->member(r), "Use of external LRG overlaps the same LRG defined in this block");

      def->insert( r );

      use->remove( r );

      uint cnt = n->req();

      for (uint k = 1; k < cnt; k++) {

        Node *nk = n->in(k);

        uint nkidx = nk->_idx;

        if (_cfg.get_block_for_node(nk) != block) {

          uint u = _names.at(nkidx);

          use->insert(u);

          DEBUG_ONLY(def_outside->insert(u);)

        }

      }

    }

#ifdef ASSERT

    def_outside->set_next(_free_IndexSet);

    _free_IndexSet = def_outside;     // Drop onto free list

#endif

    // Remove anything defined by Phis and the block start instruction

    for (uint k = i; k > 0; k--) {

      uint r = _names.at(block->get_node(k - 1)->_idx);

      def->insert(r);

      use->remove(r);

    }

    // Push these live-in things to predecessors

    for (uint l = 1; l < block->num_preds(); l++) {

      Block* p = _cfg.get_block_for_node(block->pred(l));

      add_liveout(p, use, first_pass);

      // PhiNode uses go in the live-out set of prior blocks.

      for (uint k = i; k > 0; k--) {

        add_liveout(p, _names.at(block->get_node(k-1)->in(l)->_idx), first_pass);

      }

    }

    freeset(block);

    first_pass.set(block->_pre_order);

    // Inner loop: blocks that picked up new live-out values to be propagated

    while (_worklist->size()) {

      Block* block = _worklist->pop();

      IndexSet *delta = getset(block);

      assert( delta->count(), "missing delta set" );

      // Add new-live-in to predecessors live-out sets

      for (uint l = 1; l < block->num_preds(); l++) {

        Block* predecessor = _cfg.get_block_for_node(block->pred(l));

        add_liveout(predecessor, delta, first_pass);

      }

      freeset(block);

    } // End of while-worklist-not-empty

  } // End of for-all-blocks-outer-loop

  // We explicitly clear all of the IndexSets which we are about to release.

  // This allows us to recycle their internal memory into IndexSet's free list.

  for (i = 0; i < _cfg.number_of_blocks(); i++) {

    _defs[i].clear();

    if (_deltas[i]) {

      // Is this always true?

      _deltas[i]->clear();

    }

  }

  IndexSet *free = _free_IndexSet;

  while (free != NULL) {

    IndexSet *temp = free;

    free = free->next();

    temp->clear();

  }

}

#ifndef PRODUCT

void PhaseLive::stats(uint iters) const {

}

#endif

// Get an IndexSet for a block.  Return existing one, if any.  Make a new

// empty one if a prior one does not exist.

IndexSet *PhaseLive::getset( Block *p ) {

  IndexSet *delta = _deltas[p->_pre_order-1];

  if( !delta )                  // Not on worklist?

    // Get a free set; flag as being on worklist

    delta = _deltas[p->_pre_order-1] = getfreeset();

  return delta;                 // Return set of new live-out items

}

// Pull from free list, or allocate.  Internal allocation on the returned set

// is always from thread local storage.

IndexSet *PhaseLive::getfreeset( ) {

  IndexSet *f = _free_IndexSet;

  if( !f ) {

    f = new IndexSet;

//    f->set_arena(Thread::current()->resource_area());

    f->initialize(_maxlrg, Thread::current()->resource_area());

  } else {

    // Pull from free list

    _free_IndexSet = f->next();

  //f->_cnt = 0;                        // Reset to empty

//    f->set_arena(Thread::current()->resource_area());

    f->initialize(_maxlrg, Thread::current()->resource_area());

  }

  return f;

}

// Free an IndexSet from a block.

void PhaseLive::freeset( const Block *p ) {

  IndexSet *f = _deltas[p->_pre_order-1];

  f->set_next(_free_IndexSet);

  _free_IndexSet = f;           // Drop onto free list

  _deltas[p->_pre_order-1] = NULL;

}

// Add a live-out value to a given blocks live-out set.  If it is new, then

// also add it to the delta set and stick the block on the worklist.

void PhaseLive::add_liveout( Block *p, uint r, VectorSet &first_pass ) {

  IndexSet *live = &_live[p->_pre_order-1];

  if( live->insert(r) ) {       // If actually inserted...

    // We extended the live-out set.  See if the value is generated locally.

    // If it is not, then we must extend the live-in set.

    if( !_defs[p->_pre_order-1].member( r ) ) {

      if( !_deltas[p->_pre_order-1] && // Not on worklist?

          first_pass.test(p->_pre_order) )

        _worklist->push(p);     // Actually go on worklist if already 1st pass

      getset(p)->insert(r);

    }

  }

}

// Add a vector of live-out values to a given blocks live-out set.

void PhaseLive::add_liveout( Block *p, IndexSet *lo, VectorSet &first_pass ) {

  IndexSet *live = &_live[p->_pre_order-1];

  IndexSet *defs = &_defs[p->_pre_order-1];

  IndexSet *on_worklist = _deltas[p->_pre_order-1];

  IndexSet *delta = on_worklist ? on_worklist : getfreeset();

  IndexSetIterator elements(lo);

  uint r;

  while ((r = elements.next()) != 0) {

    if( live->insert(r) &&      // If actually inserted...

        !defs->member( r ) )    // and not defined locally

      delta->insert(r);         // Then add to live-in set

  }

  if( delta->count() ) {                // If actually added things

    _deltas[p->_pre_order-1] = delta; // Flag as on worklist now

    if( !on_worklist &&         // Not on worklist?

        first_pass.test(p->_pre_order) )

      _worklist->push(p);       // Actually go on worklist if already 1st pass

  } else {                      // Nothing there; just free it

    delta->set_next(_free_IndexSet);

    _free_IndexSet = delta;     // Drop onto free list

  }

}

#ifndef PRODUCT

// Dump the live-out set for a block

void PhaseLive::dump( const Block *b ) const {

  tty->print("Block %d: ",b->_pre_order);

  tty->print("LiveOut: ");  _live[b->_pre_order-1].dump();

  uint cnt = b->number_of_nodes();

  for( uint i=0; i<cnt; i++ ) {

    tty->print("L%d/", _names.at(b->get_node(i)->_idx));

    b->get_node(i)->dump();

  }

  tty->print("\n");

}

// Verify that base pointers and derived pointers are still sane.

void PhaseChaitin::verify_base_ptrs( ResourceArea *a ) const {

#ifdef ASSERT

  Unique_Node_List worklist(a);

  for (uint i = 0; i < _cfg.number_of_blocks(); i++) {

    Block* block = _cfg.get_block(i);

    for (uint j = block->end_idx() + 1; j > 1; j--) {

      Node* n = block->get_node(j-1);

      if (n->is_Phi()) {

        break;

      }

      // Found a safepoint?

      if (n->is_MachSafePoint()) {

        MachSafePointNode *sfpt = n->as_MachSafePoint();

        JVMState* jvms = sfpt->jvms();

        if (jvms != NULL) {

          // Now scan for a live derived pointer

          if (jvms->oopoff() < sfpt->req()) {

            // Check each derived/base pair

            for (uint idx = jvms->oopoff(); idx < sfpt->req(); idx++) {

              Node *check = sfpt->in(idx);

              bool is_derived = ((idx - jvms->oopoff()) & 1) == 0;

              // search upwards through spills and spill phis for AddP

              worklist.clear();

              worklist.push(check);

              uint k = 0;

              while( k < worklist.size() ) {

                check = worklist.at(k);

                assert(check,"Bad base or derived pointer");

                // See PhaseChaitin::find_base_for_derived() for all cases.

                int isc = check->is_Copy();

                if( isc ) {

                  worklist.push(check->in(isc));

                } else if( check->is_Phi() ) {

                  for (uint m = 1; m < check->req(); m++)

                    worklist.push(check->in(m));

                } else if( check->is_Con() ) {

                  if (is_derived) {

                    // Derived is NULL+offset

                    assert(!is_derived || check->bottom_type()->is_ptr()->ptr() == TypePtr::Null,"Bad derived pointer");

                  } else {

                    assert(check->bottom_type()->is_ptr()->_offset == 0,"Bad base pointer");

                    // Base either ConP(NULL) or loadConP

                    if (check->is_Mach()) {

                      assert(check->as_Mach()->ideal_Opcode() == Op_ConP,"Bad base pointer");

                    } else {

                      assert(check->Opcode() == Op_ConP &&

                             check->bottom_type()->is_ptr()->ptr() == TypePtr::Null,"Bad base pointer");

                    }

                  }

                } else if( check->bottom_type()->is_ptr()->_offset == 0 ) {

                  if(check->is_Proj() || check->is_Mach() &&

                     (check->as_Mach()->ideal_Opcode() == Op_CreateEx ||

                      check->as_Mach()->ideal_Opcode() == Op_ThreadLocal ||

                      check->as_Mach()->ideal_Opcode() == Op_CMoveP ||

                      check->as_Mach()->ideal_Opcode() == Op_CheckCastPP ||

#ifdef _LP64

                      UseCompressedOops && check->as_Mach()->ideal_Opcode() == Op_CastPP ||

                      UseCompressedOops && check->as_Mach()->ideal_Opcode() == Op_DecodeN ||

                      UseCompressedClassPointers && check->as_Mach()->ideal_Opcode() == Op_DecodeNKlass ||

#endif

                      check->as_Mach()->ideal_Opcode() == Op_LoadP ||

                      check->as_Mach()->ideal_Opcode() == Op_LoadKlass)) {

                    // Valid nodes

                  } else {

                    check->dump();

                    assert(false,"Bad base or derived pointer");

                  }

                } else {

                  assert(is_derived,"Bad base pointer");

                  assert(check->is_Mach() && check->as_Mach()->ideal_Opcode() == Op_AddP,"Bad derived pointer");

                }

                k++;

                assert(k < 100000,"Derived pointer checking in infinite loop");

              } // End while

            }

          } // End of check for derived pointers

        } // End of Kcheck for debug info

      } // End of if found a safepoint

    } // End of forall instructions in block

  } // End of forall blocks

#endif

}

// Verify that graphs and base pointers are still sane.

void PhaseChaitin::verify( ResourceArea *a, bool verify_ifg ) const {

#ifdef ASSERT

  if( VerifyOpto || VerifyRegisterAllocator ) {

    _cfg.verify();

    verify_base_ptrs(a);

    if(verify_ifg)

      _ifg->verify(this);

  }

#endif

}

#endif