Exemple #1
0
//------------------------------compute_separating_interferences---------------
// Factored code from copy_copy that computes extra interferences from
// lengthening a live range by double-coalescing.
uint PhaseConservativeCoalesce::compute_separating_interferences(Node *dst_copy, Node *src_copy, Block *b, uint bindex, RegMask &rm, uint reg_degree, uint rm_size, uint lr1, uint lr2 ) {

  assert(!lrgs(lr1)._fat_proj, "cannot coalesce fat_proj");
  assert(!lrgs(lr2)._fat_proj, "cannot coalesce fat_proj");
  Node *prev_copy = dst_copy->in(dst_copy->is_Copy());
  Block *b2 = b;
  uint bindex2 = bindex;
  while( 1 ) {
    // Find previous instruction
    bindex2--;                  // Chain backwards 1 instruction
    while( bindex2 == 0 ) {     // At block start, find prior block
      assert( b2->num_preds() == 2, "cannot double coalesce across c-flow" );
      b2 = _phc._cfg._bbs[b2->pred(1)->_idx];
      bindex2 = b2->end_idx()-1;
    }
    // Get prior instruction
    assert(bindex2 < b2->_nodes.size(), "index out of bounds");
    Node *x = b2->_nodes[bindex2];
    if( x == prev_copy ) {      // Previous copy in copy chain?
      if( prev_copy == src_copy)// Found end of chain and all interferences
        break;                  // So break out of loop
      // Else work back one in copy chain
      prev_copy = prev_copy->in(prev_copy->is_Copy());
    } else {                    // Else collect interferences
      uint lidx = _phc.Find(x);
      // Found another def of live-range being stretched?
      if( lidx == lr1 ) return max_juint;
      if( lidx == lr2 ) return max_juint;

      // If we attempt to coalesce across a bound def
      if( lrgs(lidx).is_bound() ) {
        // Do not let the coalesced LRG expect to get the bound color
        rm.SUBTRACT( lrgs(lidx).mask() );
        // Recompute rm_size
        rm_size = rm.Size();
        //if( rm._flags ) rm_size += 1000000;
        if( reg_degree >= rm_size ) return max_juint;
      }
      if( rm.overlap(lrgs(lidx).mask()) ) {
        // Insert lidx into union LRG; returns TRUE if actually inserted
        if( _ulr.insert(lidx) ) {
          // Infinite-stack neighbors do not alter colorability, as they
          // can always color to some other color.
          if( !lrgs(lidx).mask().is_AllStack() ) {
            // If this coalesce will make any new neighbor uncolorable,
            // do not coalesce.
            if( lrgs(lidx).just_lo_degree() )
              return max_juint;
            // Bump our degree
            if( ++reg_degree >= rm_size )
              return max_juint;
          } // End of if not infinite-stack neighbor
        } // End of if actually inserted
      } // End of if live range overlaps
    } // End of else collect interferences for 1 node
  } // End of while forever, scan back for interferences
  return reg_degree;
}
Exemple #2
0
uint IndexSet::lrg_union(uint lr1, uint lr2,
                         const uint fail_degree,
                         const PhaseIFG *ifg,
                         const RegMask &mask ) {
  IndexSet *one = ifg->neighbors(lr1);
  IndexSet *two = ifg->neighbors(lr2);
  LRG &lrg1 = ifg->lrgs(lr1);
  LRG &lrg2 = ifg->lrgs(lr2);
#ifdef ASSERT
  assert(_max_elements == one->_max_elements, "max element mismatch");
  check_watch("union destination");
  one->check_watch("union source");
  two->check_watch("union source");
#endif

  // Compute the degree of the combined live-range.  The combined
  // live-range has the union of the original live-ranges' neighbors set as
  // well as the neighbors of all intermediate copies, minus those neighbors
  // that can not use the intersected allowed-register-set.

  // Copy the larger set.  Insert the smaller set into the larger.
  if (two->count() > one->count()) {
    IndexSet *temp = one;
    one = two;
    two = temp;
  }

  clear();

  // Used to compute degree of register-only interferences.  Infinite-stack
  // neighbors do not alter colorability, as they can always color to some
  // other color.  (A variant of the Briggs assertion)
  uint reg_degree = 0;

  uint element;
  // Load up the combined interference set with the neighbors of one
  IndexSetIterator elements(one);
  while ((element = elements.next()) != 0) {
    LRG &lrg = ifg->lrgs(element);
    if (mask.overlap(lrg.mask())) {
      insert(element);
      if( !lrg.mask().is_AllStack() ) {
        reg_degree += lrg1.compute_degree(lrg);
        if( reg_degree >= fail_degree ) return reg_degree;
      } else {
        // !!!!! Danger!  No update to reg_degree despite having a neighbor.
        // A variant of the Briggs assertion.
        // Not needed if I simplify during coalesce, ala George/Appel.
        assert( lrg.lo_degree(), "" );
      }
    }
  }
  // Add neighbors of two as well
  IndexSetIterator elements2(two);
  while ((element = elements2.next()) != 0) {
    LRG &lrg = ifg->lrgs(element);
    if (mask.overlap(lrg.mask())) {
      if (insert(element)) {
        if( !lrg.mask().is_AllStack() ) {
          reg_degree += lrg2.compute_degree(lrg);
          if( reg_degree >= fail_degree ) return reg_degree;
        } else {
          // !!!!! Danger!  No update to reg_degree despite having a neighbor.
          // A variant of the Briggs assertion.
          // Not needed if I simplify during coalesce, ala George/Appel.
          assert( lrg.lo_degree(), "" );
        }
      }
    }
  }

  return reg_degree;
}