hotspot/src/share/vm/opto/split_if.cpp
author never
Thu, 18 Feb 2010 15:05:10 -0800
changeset 5024 d7ac73e48389
parent 4643 61c659c91c57
child 5547 f4b087cbb361
permissions -rw-r--r--
6663854: assert(n != __null,"Bad immediate dominator info.") in C2 with -Xcomp Reviewed-by: kvn
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/*
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d7ac73e48389 6663854: assert(n != __null,"Bad immediate dominator info.") in C2 with -Xcomp
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 * Copyright 1999-2010 Sun Microsystems, Inc.  All Rights Reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 *
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 */
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#include "incls/_precompiled.incl"
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#include "incls/_split_if.cpp.incl"
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//------------------------------split_thru_region------------------------------
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// Split Node 'n' through merge point.
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Node *PhaseIdealLoop::split_thru_region( Node *n, Node *region ) {
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  uint wins = 0;
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  assert( n->is_CFG(), "" );
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  assert( region->is_Region(), "" );
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  Node *r = new (C, region->req()) RegionNode( region->req() );
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  IdealLoopTree *loop = get_loop( n );
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  for( uint i = 1; i < region->req(); i++ ) {
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    Node *x = n->clone();
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    Node *in0 = n->in(0);
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    if( in0->in(0) == region ) x->set_req( 0, in0->in(i) );
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    for( uint j = 1; j < n->req(); j++ ) {
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      Node *in = n->in(j);
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      if( get_ctrl(in) == region )
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        x->set_req( j, in->in(i) );
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    }
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    _igvn.register_new_node_with_optimizer(x);
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    set_loop(x, loop);
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    set_idom(x, x->in(0), dom_depth(x->in(0))+1);
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    r->init_req(i, x);
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  }
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  // Record region
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  r->set_req(0,region);         // Not a TRUE RegionNode
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  _igvn.register_new_node_with_optimizer(r);
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  set_loop(r, loop);
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  if( !loop->_child )
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    loop->_body.push(r);
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  return r;
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}
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//------------------------------split_up---------------------------------------
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// Split block-local op up through the phis to empty the current block
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bool PhaseIdealLoop::split_up( Node *n, Node *blk1, Node *blk2 ) {
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  if( n->is_CFG() ) {
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    assert( n->in(0) != blk1, "Lousy candidate for split-if" );
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    return false;
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  }
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  if( get_ctrl(n) != blk1 && get_ctrl(n) != blk2 )
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    return false;               // Not block local
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  if( n->is_Phi() ) return false; // Local PHIs are expected
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  // Recursively split-up inputs
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  for (uint i = 1; i < n->req(); i++) {
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    if( split_up( n->in(i), blk1, blk2 ) ) {
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      // Got split recursively and self went dead?
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      if (n->outcnt() == 0)
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        _igvn.remove_dead_node(n);
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      return true;
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    }
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  }
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  // Check for needing to clone-up a compare.  Can't do that, it forces
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  // another (nested) split-if transform.  Instead, clone it "down".
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  if( n->is_Cmp() ) {
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    assert(get_ctrl(n) == blk2 || get_ctrl(n) == blk1, "must be in block with IF");
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    // Check for simple Cmp/Bool/CMove which we can clone-up.  Cmp/Bool/CMove
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    // sequence can have no other users and it must all reside in the split-if
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    // block.  Non-simple Cmp/Bool/CMove sequences are 'cloned-down' below -
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    // private, per-use versions of the Cmp and Bool are made.  These sink to
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    // the CMove block.  If the CMove is in the split-if block, then in the
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    // next iteration this will become a simple Cmp/Bool/CMove set to clone-up.
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    Node *bol, *cmov;
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    if( !(n->outcnt() == 1 && n->unique_out()->is_Bool() &&
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          (bol = n->unique_out()->as_Bool()) &&
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          (get_ctrl(bol) == blk1 ||
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           get_ctrl(bol) == blk2) &&
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          bol->outcnt() == 1 &&
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          bol->unique_out()->is_CMove() &&
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          (cmov = bol->unique_out()->as_CMove()) &&
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          (get_ctrl(cmov) == blk1 ||
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           get_ctrl(cmov) == blk2) ) ) {
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      // Must clone down
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#ifndef PRODUCT
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      if( PrintOpto && VerifyLoopOptimizations ) {
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        tty->print("Cloning down: ");
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        n->dump();
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      }
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#endif
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      // Clone down any block-local BoolNode uses of this CmpNode
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      for (DUIterator i = n->outs(); n->has_out(i); i++) {
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        Node* bol = n->out(i);
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        assert( bol->is_Bool(), "" );
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        if (bol->outcnt() == 1) {
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          Node* use = bol->unique_out();
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          Node *use_c = use->is_If() ? use->in(0) : get_ctrl(use);
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          if (use_c == blk1 || use_c == blk2) {
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            continue;
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          }
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        }
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        if (get_ctrl(bol) == blk1 || get_ctrl(bol) == blk2) {
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          // Recursively sink any BoolNode
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#ifndef PRODUCT
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          if( PrintOpto && VerifyLoopOptimizations ) {
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            tty->print("Cloning down: ");
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            bol->dump();
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          }
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#endif
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          for (DUIterator_Last jmin, j = bol->last_outs(jmin); j >= jmin; --j) {
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            // Uses are either IfNodes or CMoves
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            Node* iff = bol->last_out(j);
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            assert( iff->in(1) == bol, "" );
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            // Get control block of either the CMove or the If input
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            Node *iff_ctrl = iff->is_If() ? iff->in(0) : get_ctrl(iff);
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            Node *x = bol->clone();
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            register_new_node(x, iff_ctrl);
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            _igvn.hash_delete(iff);
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            iff->set_req(1, x);
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            _igvn._worklist.push(iff);
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          }
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          _igvn.remove_dead_node( bol );
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          --i;
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        }
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      }
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      // Clone down this CmpNode
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      for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) {
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        Node* bol = n->last_out(j);
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        assert( bol->in(1) == n, "" );
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        Node *x = n->clone();
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        register_new_node(x, get_ctrl(bol));
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        _igvn.hash_delete(bol);
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        bol->set_req(1, x);
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        _igvn._worklist.push(bol);
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      }
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      _igvn.remove_dead_node( n );
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      return true;
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    }
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  }
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  // See if splitting-up a Store.  Any anti-dep loads must go up as
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  // well.  An anti-dep load might be in the wrong block, because in
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  // this particular layout/schedule we ignored anti-deps and allow
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  // memory to be alive twice.  This only works if we do the same
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  // operations on anti-dep loads as we do their killing stores.
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  if( n->is_Store() && n->in(MemNode::Memory)->in(0) == n->in(0) ) {
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    // Get store's memory slice
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    int alias_idx = C->get_alias_index(_igvn.type(n->in(MemNode::Address))->is_ptr());
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    // Get memory-phi anti-dep loads will be using
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    Node *memphi = n->in(MemNode::Memory);
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    assert( memphi->is_Phi(), "" );
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    // Hoist any anti-dep load to the splitting block;
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    // it will then "split-up".
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    for (DUIterator_Fast imax,i = memphi->fast_outs(imax); i < imax; i++) {
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      Node *load = memphi->fast_out(i);
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      if( load->is_Load() && alias_idx == C->get_alias_index(_igvn.type(load->in(MemNode::Address))->is_ptr()) )
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        set_ctrl(load,blk1);
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    }
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  }
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  // Found some other Node; must clone it up
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#ifndef PRODUCT
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  if( PrintOpto && VerifyLoopOptimizations ) {
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    tty->print("Cloning up: ");
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    n->dump();
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  }
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#endif
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  // ConvI2L may have type information on it which becomes invalid if
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  // it moves up in the graph so change any clones so widen the type
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  // to TypeLong::INT when pushing it up.
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  const Type* rtype = NULL;
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  if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::INT) {
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    rtype = TypeLong::INT;
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  }
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1
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  // Now actually split-up this guy.  One copy per control path merging.
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  Node *phi = PhiNode::make_blank(blk1, n);
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  for( uint j = 1; j < blk1->req(); j++ ) {
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    Node *x = n->clone();
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    // Widen the type of the ConvI2L when pushing up.
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    if (rtype != NULL) x->as_Type()->set_type(rtype);
1
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    if( n->in(0) && n->in(0) == blk1 )
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      x->set_req( 0, blk1->in(j) );
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    for( uint i = 1; i < n->req(); i++ ) {
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      Node *m = n->in(i);
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      if( get_ctrl(m) == blk1 ) {
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        assert( m->in(0) == blk1, "" );
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        x->set_req( i, m->in(j) );
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      }
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    }
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    register_new_node( x, blk1->in(j) );
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    phi->init_req( j, x );
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  }
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  // Announce phi to optimizer
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  register_new_node(phi, blk1);
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  // Remove cloned-up value from optimizer; use phi instead
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  _igvn.hash_delete(n);
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  _igvn.subsume_node( n, phi );
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  // (There used to be a self-recursive call to split_up() here,
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  // but it is not needed.  All necessary forward walking is done
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  // by do_split_if() below.)
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  return true;
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}
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//------------------------------register_new_node------------------------------
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void PhaseIdealLoop::register_new_node( Node *n, Node *blk ) {
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  assert(!n->is_CFG(), "must be data node");
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  _igvn.register_new_node_with_optimizer(n);
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  set_ctrl(n, blk);
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  IdealLoopTree *loop = get_loop(blk);
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  if( !loop->_child )
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    loop->_body.push(n);
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}
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//------------------------------small_cache------------------------------------
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struct small_cache : public Dict {
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  small_cache() : Dict( cmpkey, hashptr ) {}
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  Node *probe( Node *use_blk ) { return (Node*)((*this)[use_blk]); }
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  void lru_insert( Node *use_blk, Node *new_def ) { Insert(use_blk,new_def); }
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};
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//------------------------------spinup-----------------------------------------
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// "Spin up" the dominator tree, starting at the use site and stopping when we
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// find the post-dominating point.
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// We must be at the merge point which post-dominates 'new_false' and
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// 'new_true'.  Figure out which edges into the RegionNode eventually lead up
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// to false and which to true.  Put in a PhiNode to merge values; plug in
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// the appropriate false-arm or true-arm values.  If some path leads to the
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// original IF, then insert a Phi recursively.
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Node *PhaseIdealLoop::spinup( Node *iff_dom, Node *new_false, Node *new_true, Node *use_blk, Node *def, small_cache *cache ) {
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  if (use_blk->is_top())        // Handle dead uses
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    return use_blk;
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  Node *prior_n = (Node*)0xdeadbeef;
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  Node *n = use_blk;            // Get path input
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  assert( use_blk != iff_dom, "" );
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  // Here's the "spinup" the dominator tree loop.  Do a cache-check
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  // along the way, in case we've come this way before.
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  while( n != iff_dom ) {       // Found post-dominating point?
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    prior_n = n;
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    n = idom(n);                // Search higher
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    Node *s = cache->probe( prior_n ); // Check cache
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    if( s ) return s;           // Cache hit!
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  }
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  Node *phi_post;
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  if( prior_n == new_false || prior_n == new_true ) {
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    phi_post = def->clone();
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    phi_post->set_req(0, prior_n );
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    register_new_node(phi_post, prior_n);
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  } else {
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    // This method handles both control uses (looking for Regions) or data
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    // uses (looking for Phis).  If looking for a control use, then we need
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    // to insert a Region instead of a Phi; however Regions always exist
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    // previously (the hash_find_insert below would always hit) so we can
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    // return the existing Region.
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    if( def->is_CFG() ) {
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      phi_post = prior_n;       // If looking for CFG, return prior
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    } else {
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      assert( def->is_Phi(), "" );
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      assert( prior_n->is_Region(), "must be a post-dominating merge point" );
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      // Need a Phi here
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      phi_post = PhiNode::make_blank(prior_n, def);
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      // Search for both true and false on all paths till find one.
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      for( uint i = 1; i < phi_post->req(); i++ ) // For all paths
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        phi_post->init_req( i, spinup( iff_dom, new_false, new_true, prior_n->in(i), def, cache ) );
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      Node *t = _igvn.hash_find_insert(phi_post);
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      if( t ) {                 // See if we already have this one
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        // phi_post will not be used, so kill it
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        _igvn.remove_dead_node(phi_post);
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        phi_post->destruct();
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        phi_post = t;
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      } else {
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        register_new_node( phi_post, prior_n );
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      }
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    }
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   304
  }
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  // Update cache everywhere
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  prior_n = (Node*)0xdeadbeef;  // Reset IDOM walk
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  n = use_blk;                  // Get path input
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  // Spin-up the idom tree again, basically doing path-compression.
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  // Insert cache entries along the way, so that if we ever hit this
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   311
  // point in the IDOM tree again we'll stop immediately on a cache hit.
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   312
  while( n != iff_dom ) {       // Found post-dominating point?
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   313
    prior_n = n;
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   314
    n = idom(n);                // Search higher
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    cache->lru_insert( prior_n, phi_post ); // Fill cache
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   316
  } // End of while not gone high enough
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   317
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  return phi_post;
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   319
}
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   320
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   321
//------------------------------find_use_block---------------------------------
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// Find the block a USE is in.  Normally USE's are in the same block as the
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// using instruction.  For Phi-USE's, the USE is in the predecessor block
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   324
// along the corresponding path.
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Node *PhaseIdealLoop::find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ) {
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  // CFG uses are their own block
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  if( use->is_CFG() )
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   328
    return use;
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   329
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   330
  if( use->is_Phi() ) {         // Phi uses in prior block
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   331
    // Grab the first Phi use; there may be many.
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   332
    // Each will be handled as a separate iteration of
1
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   333
    // the "while( phi->outcnt() )" loop.
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   334
    uint j;
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   335
    for( j = 1; j < use->req(); j++ )
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   336
      if( use->in(j) == def )
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   337
        break;
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   338
    assert( j < use->req(), "def should be among use's inputs" );
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   339
    return use->in(0)->in(j);
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   340
  }
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   341
  // Normal (non-phi) use
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   342
  Node *use_blk = get_ctrl(use);
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   343
  // Some uses are directly attached to the old (and going away)
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  // false and true branches.
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   345
  if( use_blk == old_false ) {
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   346
    use_blk = new_false;
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   347
    set_ctrl(use, new_false);
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   348
  }
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   349
  if( use_blk == old_true ) {
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   350
    use_blk = new_true;
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    set_ctrl(use, new_true);
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  }
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   353
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   354
  if (use_blk == NULL) {        // He's dead, Jim
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   355
    _igvn.hash_delete(use);
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   356
    _igvn.subsume_node(use, C->top());
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   357
  }
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   358
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   359
  return use_blk;
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   360
}
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   361
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   362
//------------------------------handle_use-------------------------------------
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   363
// Handle uses of the merge point.  Basically, split-if makes the merge point
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   364
// go away so all uses of the merge point must go away as well.  Most block
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   365
// local uses have already been split-up, through the merge point.  Uses from
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   366
// far below the merge point can't always be split up (e.g., phi-uses are
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   367
// pinned) and it makes too much stuff live.  Instead we use a path-based
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// solution to move uses down.
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   369
//
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   370
// If the use is along the pre-split-CFG true branch, then the new use will
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   371
// be from the post-split-CFG true merge point.  Vice-versa for the false
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// path.  Some uses will be along both paths; then we sink the use to the
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   373
// post-dominating location; we may need to insert a Phi there.
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   374
void PhaseIdealLoop::handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   375
489c9b5090e2 Initial load
duke
parents:
diff changeset
   376
  Node *use_blk = find_use_block(use,def,old_false,new_false,old_true,new_true);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   377
  if( !use_blk ) return;        // He's dead, Jim
489c9b5090e2 Initial load
duke
parents:
diff changeset
   378
489c9b5090e2 Initial load
duke
parents:
diff changeset
   379
  // Walk up the dominator tree until I hit either the old IfFalse, the old
489c9b5090e2 Initial load
duke
parents:
diff changeset
   380
  // IfTrue or the old If.  Insert Phis where needed.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   381
  Node *new_def = spinup( region_dom, new_false, new_true, use_blk, def, cache );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   382
489c9b5090e2 Initial load
duke
parents:
diff changeset
   383
  // Found where this USE goes.  Re-point him.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   384
  uint i;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   385
  for( i = 0; i < use->req(); i++ )
489c9b5090e2 Initial load
duke
parents:
diff changeset
   386
    if( use->in(i) == def )
489c9b5090e2 Initial load
duke
parents:
diff changeset
   387
      break;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   388
  assert( i < use->req(), "def should be among use's inputs" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   389
  _igvn.hash_delete(use);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   390
  use->set_req(i, new_def);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   391
  _igvn._worklist.push(use);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   392
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   393
489c9b5090e2 Initial load
duke
parents:
diff changeset
   394
//------------------------------do_split_if------------------------------------
489c9b5090e2 Initial load
duke
parents:
diff changeset
   395
// Found an If getting its condition-code input from a Phi in the same block.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   396
// Split thru the Region.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   397
void PhaseIdealLoop::do_split_if( Node *iff ) {
489c9b5090e2 Initial load
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parents:
diff changeset
   398
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   399
  if( PrintOpto && VerifyLoopOptimizations )
489c9b5090e2 Initial load
duke
parents:
diff changeset
   400
    tty->print_cr("Split-if");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   401
#endif
489c9b5090e2 Initial load
duke
parents:
diff changeset
   402
  C->set_major_progress();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   403
  Node *region = iff->in(0);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   404
  Node *region_dom = idom(region);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   405
489c9b5090e2 Initial load
duke
parents:
diff changeset
   406
  // We are going to clone this test (and the control flow with it) up through
489c9b5090e2 Initial load
duke
parents:
diff changeset
   407
  // the incoming merge point.  We need to empty the current basic block.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   408
  // Clone any instructions which must be in this block up through the merge
489c9b5090e2 Initial load
duke
parents:
diff changeset
   409
  // point.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   410
  DUIterator i, j;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   411
  bool progress = true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   412
  while (progress) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   413
    progress = false;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   414
    for (i = region->outs(); region->has_out(i); i++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   415
      Node* n = region->out(i);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   416
      if( n == region ) continue;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   417
      // The IF to be split is OK.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   418
      if( n == iff ) continue;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   419
      if( !n->is_Phi() ) {      // Found pinned memory op or such
489c9b5090e2 Initial load
duke
parents:
diff changeset
   420
        if (split_up(n, region, iff)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   421
          i = region->refresh_out_pos(i);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   422
          progress = true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   423
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   424
        continue;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   425
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   426
      assert( n->in(0) == region, "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   427
489c9b5090e2 Initial load
duke
parents:
diff changeset
   428
      // Recursively split up all users of a Phi
489c9b5090e2 Initial load
duke
parents:
diff changeset
   429
      for (j = n->outs(); n->has_out(j); j++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   430
        Node* m = n->out(j);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   431
        // If m is dead, throw it away, and declare progress
489c9b5090e2 Initial load
duke
parents:
diff changeset
   432
        if (_nodes[m->_idx] == NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   433
          _igvn.remove_dead_node(m);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   434
          // fall through
489c9b5090e2 Initial load
duke
parents:
diff changeset
   435
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   436
        else if (m != iff && split_up(m, region, iff)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   437
          // fall through
489c9b5090e2 Initial load
duke
parents:
diff changeset
   438
        } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   439
          continue;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   440
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   441
        // Something unpredictable changed.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   442
        // Tell the iterators to refresh themselves, and rerun the loop.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   443
        i = region->refresh_out_pos(i);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   444
        j = region->refresh_out_pos(j);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   445
        progress = true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   446
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   447
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   448
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   449
489c9b5090e2 Initial load
duke
parents:
diff changeset
   450
  // Now we have no instructions in the block containing the IF.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   451
  // Split the IF.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   452
  Node *new_iff = split_thru_region( iff, region );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   453
489c9b5090e2 Initial load
duke
parents:
diff changeset
   454
  // Replace both uses of 'new_iff' with Regions merging True/False
489c9b5090e2 Initial load
duke
parents:
diff changeset
   455
  // paths.  This makes 'new_iff' go dead.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   456
  Node *old_false, *old_true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   457
  Node *new_false, *new_true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   458
  for (DUIterator_Last j2min, j2 = iff->last_outs(j2min); j2 >= j2min; --j2) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   459
    Node *ifp = iff->last_out(j2);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   460
    assert( ifp->Opcode() == Op_IfFalse || ifp->Opcode() == Op_IfTrue, "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   461
    ifp->set_req(0, new_iff);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   462
    Node *ifpx = split_thru_region( ifp, region );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   463
489c9b5090e2 Initial load
duke
parents:
diff changeset
   464
    // Replace 'If' projection of a Region with a Region of
489c9b5090e2 Initial load
duke
parents:
diff changeset
   465
    // 'If' projections.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   466
    ifpx->set_req(0, ifpx);       // A TRUE RegionNode
489c9b5090e2 Initial load
duke
parents:
diff changeset
   467
489c9b5090e2 Initial load
duke
parents:
diff changeset
   468
    // Setup dominator info
489c9b5090e2 Initial load
duke
parents:
diff changeset
   469
    set_idom(ifpx, region_dom, dom_depth(region_dom) + 1);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   470
489c9b5090e2 Initial load
duke
parents:
diff changeset
   471
    // Check for splitting loop tails
489c9b5090e2 Initial load
duke
parents:
diff changeset
   472
    if( get_loop(iff)->tail() == ifp )
489c9b5090e2 Initial load
duke
parents:
diff changeset
   473
      get_loop(iff)->_tail = ifpx;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   474
489c9b5090e2 Initial load
duke
parents:
diff changeset
   475
    // Replace in the graph with lazy-update mechanism
489c9b5090e2 Initial load
duke
parents:
diff changeset
   476
    new_iff->set_req(0, new_iff); // hook self so it does not go dead
489c9b5090e2 Initial load
duke
parents:
diff changeset
   477
    lazy_replace_proj( ifp, ifpx );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   478
    new_iff->set_req(0, region);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   479
489c9b5090e2 Initial load
duke
parents:
diff changeset
   480
    // Record bits for later xforms
489c9b5090e2 Initial load
duke
parents:
diff changeset
   481
    if( ifp->Opcode() == Op_IfFalse ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   482
      old_false = ifp;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   483
      new_false = ifpx;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   484
    } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   485
      old_true = ifp;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   486
      new_true = ifpx;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   487
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   488
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   489
  _igvn.remove_dead_node(new_iff);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   490
  // Lazy replace IDOM info with the region's dominator
489c9b5090e2 Initial load
duke
parents:
diff changeset
   491
  lazy_replace( iff, region_dom );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   492
489c9b5090e2 Initial load
duke
parents:
diff changeset
   493
  // Now make the original merge point go dead, by handling all its uses.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   494
  small_cache region_cache;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   495
  // Preload some control flow in region-cache
489c9b5090e2 Initial load
duke
parents:
diff changeset
   496
  region_cache.lru_insert( new_false, new_false );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   497
  region_cache.lru_insert( new_true , new_true  );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   498
  // Now handle all uses of the splitting block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   499
  for (DUIterator_Last kmin, k = region->last_outs(kmin); k >= kmin; --k) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   500
    Node* phi = region->last_out(k);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   501
    if( !phi->in(0) ) {         // Dead phi?  Remove it
489c9b5090e2 Initial load
duke
parents:
diff changeset
   502
      _igvn.remove_dead_node(phi);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   503
      continue;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   504
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   505
    assert( phi->in(0) == region, "" );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   506
    if( phi == region ) {       // Found the self-reference
489c9b5090e2 Initial load
duke
parents:
diff changeset
   507
      phi->set_req(0, NULL);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   508
      continue;                 // Break the self-cycle
489c9b5090e2 Initial load
duke
parents:
diff changeset
   509
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   510
    // Expected common case: Phi hanging off of Region
489c9b5090e2 Initial load
duke
parents:
diff changeset
   511
    if( phi->is_Phi() ) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   512
      // Need a per-def cache.  Phi represents a def, so make a cache
489c9b5090e2 Initial load
duke
parents:
diff changeset
   513
      small_cache phi_cache;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   514
489c9b5090e2 Initial load
duke
parents:
diff changeset
   515
      // Inspect all Phi uses to make the Phi go dead
489c9b5090e2 Initial load
duke
parents:
diff changeset
   516
      for (DUIterator_Last lmin, l = phi->last_outs(lmin); l >= lmin; --l) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   517
        Node* use = phi->last_out(l);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   518
        // Compute the new DEF for this USE.  New DEF depends on the path
489c9b5090e2 Initial load
duke
parents:
diff changeset
   519
        // taken from the original DEF to the USE.  The new DEF may be some
489c9b5090e2 Initial load
duke
parents:
diff changeset
   520
        // collection of PHI's merging values from different paths.  The Phis
489c9b5090e2 Initial load
duke
parents:
diff changeset
   521
        // inserted depend only on the location of the USE.  We use a
489c9b5090e2 Initial load
duke
parents:
diff changeset
   522
        // 2-element cache to handle multiple uses from the same block.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   523
        handle_use( use, phi, &phi_cache, region_dom, new_false, new_true, old_false, old_true );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   524
      } // End of while phi has uses
489c9b5090e2 Initial load
duke
parents:
diff changeset
   525
489c9b5090e2 Initial load
duke
parents:
diff changeset
   526
      // Because handle_use might relocate region->_out,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   527
      // we must refresh the iterator.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   528
      k = region->last_outs(kmin);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   529
489c9b5090e2 Initial load
duke
parents:
diff changeset
   530
      // Remove the dead Phi
489c9b5090e2 Initial load
duke
parents:
diff changeset
   531
      _igvn.remove_dead_node( phi );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   532
489c9b5090e2 Initial load
duke
parents:
diff changeset
   533
    } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   534
      // Random memory op guarded by Region.  Compute new DEF for USE.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   535
      handle_use( phi, region, &region_cache, region_dom, new_false, new_true, old_false, old_true );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   536
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   537
489c9b5090e2 Initial load
duke
parents:
diff changeset
   538
  } // End of while merge point has phis
489c9b5090e2 Initial load
duke
parents:
diff changeset
   539
489c9b5090e2 Initial load
duke
parents:
diff changeset
   540
  // Any leftover bits in the splitting block must not have depended on local
489c9b5090e2 Initial load
duke
parents:
diff changeset
   541
  // Phi inputs (these have already been split-up).  Hence it's safe to hoist
489c9b5090e2 Initial load
duke
parents:
diff changeset
   542
  // these guys to the dominating point.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   543
  lazy_replace( region, region_dom );
489c9b5090e2 Initial load
duke
parents:
diff changeset
   544
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   545
  if( VerifyLoopOptimizations ) verify();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   546
#endif
489c9b5090e2 Initial load
duke
parents:
diff changeset
   547
}