truffle: src/share/vm/opto/loopopts.cpp comparison

comparison src/share/vm/opto/loopopts.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	e2ae28d2ce91

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+:a61af66fc99e
+/*
+* Copyright 1999-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+#include "incls/_precompiled.incl"
+#include "incls/_loopopts.cpp.incl"
+//=============================================================================
+//------------------------------split_thru_phi---------------------------------
+// Split Node 'n' through merge point if there is enough win.
+Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
+int wins = 0;
+assert( !n->is_CFG(), "" );
+assert( region->is_Region(), "" );
+Node *phi = new (C, region->req()) PhiNode( region, n->bottom_type() );
+uint old_unique = C->unique();
+for( uint i = 1; i < region->req(); i++ ) {
+Node *x;
+Node* the_clone = NULL;
+if( region->in(i) == C->top() ) {
+x = C->top();             // Dead path?  Use a dead data op
+} else {
+x = n->clone();           // Else clone up the data op
+the_clone = x;            // Remember for possible deletion.
+// Alter data node to use pre-phi inputs
+if( n->in(0) == region )
+x->set_req( 0, region->in(i) );
+for( uint j = 1; j < n->req(); j++ ) {
+Node *in = n->in(j);
+if( in->is_Phi() && in->in(0) == region )
+x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
+}
+}
+// Check for a 'win' on some paths
+const Type *t = x->Value(&_igvn);
+bool singleton = t->singleton();
+// A TOP singleton indicates that there are no possible values incoming
+// along a particular edge. In most cases, this is OK, and the Phi will
+// be eliminated later in an Ideal call. However, we can't allow this to
+// happen if the singleton occurs on loop entry, as the elimination of
+// the PhiNode may cause the resulting node to migrate back to a previous
+// loop iteration.
+if( singleton && t == Type::TOP ) {
+// Is_Loop() == false does not confirm the absence of a loop (e.g., an
+// irreducible loop may not be indicated by an affirmative is_Loop());
+// therefore, the only top we can split thru a phi is on a backedge of
+// a loop.
+singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
+}
+if( singleton ) {
+wins++;
+x = ((PhaseGVN&)_igvn).makecon(t);
+} else {
+// We now call Identity to try to simplify the cloned node.
+// Note that some Identity methods call phase->type(this).
+// Make sure that the type array is big enough for
+// our new node, even though we may throw the node away.
+// (Note: This tweaking with igvn only works because x is a new node.)
+_igvn.set_type(x, t);
+Node *y = x->Identity(&_igvn);
+if( y != x ) {
+wins++;
+x = y;
+} else {
+y = _igvn.hash_find(x);
+if( y ) {
+wins++;
+x = y;
+} else {
+// Else x is a new node we are keeping
+// We do not need register_new_node_with_optimizer
+// because set_type has already been called.
+_igvn._worklist.push(x);
+}
+}
+}
+if (x != the_clone && the_clone != NULL)
+_igvn.remove_dead_node(the_clone);
+phi->set_req( i, x );
+}
+// Too few wins?
+if( wins <= policy ) {
+_igvn.remove_dead_node(phi);
+return NULL;
+}
+// Record Phi
+register_new_node( phi, region );
+for( uint i2 = 1; i2 < phi->req(); i2++ ) {
+Node *x = phi->in(i2);
+// If we commoned up the cloned 'x' with another existing Node,
+// the existing Node picks up a new use.  We need to make the
+// existing Node occur higher up so it dominates its uses.
+Node *old_ctrl;
+IdealLoopTree *old_loop;
+// The occasional new node
+if( x->_idx >= old_unique ) {   // Found a new, unplaced node?
+old_ctrl = x->is_Con() ? C->root() : NULL;
+old_loop = NULL;              // Not in any prior loop
+} else {
+old_ctrl = x->is_Con() ? C->root() : get_ctrl(x);
+old_loop = get_loop(old_ctrl); // Get prior loop
+}
+// New late point must dominate new use
+Node *new_ctrl = dom_lca( old_ctrl, region->in(i2) );
+// Set new location
+set_ctrl(x, new_ctrl);
+IdealLoopTree *new_loop = get_loop( new_ctrl );
+// If changing loop bodies, see if we need to collect into new body
+if( old_loop != new_loop ) {
+if( old_loop && !old_loop->_child )
+old_loop->_body.yank(x);
+if( !new_loop->_child )
+new_loop->_body.push(x);  // Collect body info
+}
+}
+return phi;
+}
+//------------------------------dominated_by------------------------------------
+// Replace the dominated test with an obvious true or false.  Place it on the
+// IGVN worklist for later cleanup.  Move control-dependent data Nodes on the
+// live path up to the dominating control.
+void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff ) {
+#ifndef PRODUCT
+if( VerifyLoopOptimizations && PrintOpto ) tty->print_cr("dominating test");
+#endif
+// prevdom is the dominating projection of the dominating test.
+assert( iff->is_If(), "" );
+assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
+int pop = prevdom->Opcode();
+assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
+// 'con' is set to true or false to kill the dominated test.
+Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
+set_ctrl(con, C->root()); // Constant gets a new use
+// Hack the dominated test
+_igvn.hash_delete(iff);
+iff->set_req(1, con);
+_igvn._worklist.push(iff);
+// If I dont have a reachable TRUE and FALSE path following the IfNode then
+// I can assume this path reaches an infinite loop.  In this case it's not
+// important to optimize the data Nodes - either the whole compilation will
+// be tossed or this path (and all data Nodes) will go dead.
+if( iff->outcnt() != 2 ) return;
+// Make control-dependent data Nodes on the live path (path that will remain
+// once the dominated IF is removed) become control-dependent on the
+// dominating projection.
+Node* dp = ((IfNode*)iff)->proj_out(pop == Op_IfTrue);
+IdealLoopTree *old_loop = get_loop(dp);
+for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
+Node* cd = dp->fast_out(i); // Control-dependent node
+if( cd->depends_only_on_test() ) {
+assert( cd->in(0) == dp, "" );
+_igvn.hash_delete( cd );
+cd->set_req(0, prevdom);
+set_early_ctrl( cd );
+_igvn._worklist.push(cd);
+IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
+if( old_loop != new_loop ) {
+if( !old_loop->_child ) old_loop->_body.yank(cd);
+if( !new_loop->_child ) new_loop->_body.push(cd);
+}
+--i;
+--imax;
+}
+}
+}
+//------------------------------has_local_phi_input----------------------------
+// Return TRUE if 'n' has Phi inputs from its local block and no other
+// block-local inputs (all non-local-phi inputs come from earlier blocks)
+Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
+Node *n_ctrl = get_ctrl(n);
+// See if some inputs come from a Phi in this block, or from before
+// this block.
+uint i;
+for( i = 1; i < n->req(); i++ ) {
+Node *phi = n->in(i);
+if( phi->is_Phi() && phi->in(0) == n_ctrl )
+break;
+}
+if( i >= n->req() )
+return NULL;                // No Phi inputs; nowhere to clone thru
+// Check for inputs created between 'n' and the Phi input.  These
+// must split as well; they have already been given the chance
+// (courtesy of a post-order visit) and since they did not we must
+// recover the 'cost' of splitting them by being very profitable
+// when splitting 'n'.  Since this is unlikely we simply give up.
+for( i = 1; i < n->req(); i++ ) {
+Node *m = n->in(i);
+if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
+// We allow the special case of AddP's with no local inputs.
+// This allows us to split-up address expressions.
+if (m->is_AddP() &&
+get_ctrl(m->in(2)) != n_ctrl &&
+get_ctrl(m->in(3)) != n_ctrl) {
+// Move the AddP up to dominating point
+set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
+continue;
+}
+return NULL;
+}
+}
+return n_ctrl;
+}
+//------------------------------remix_address_expressions----------------------
+// Rework addressing expressions to get the most loop-invariant stuff
+// moved out.  We'd like to do all associative operators, but it's especially
+// important (common) to do address expressions.
+Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
+if (!has_ctrl(n))  return NULL;
+Node *n_ctrl = get_ctrl(n);
+IdealLoopTree *n_loop = get_loop(n_ctrl);
+// See if 'n' mixes loop-varying and loop-invariant inputs and
+// itself is loop-varying.
+// Only interested in binary ops (and AddP)
+if( n->req() < 3 || n->req() > 4 ) return NULL;
+Node *n1_ctrl = get_ctrl(n->in(                    1));
+Node *n2_ctrl = get_ctrl(n->in(                    2));
+Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
+IdealLoopTree *n1_loop = get_loop( n1_ctrl );
+IdealLoopTree *n2_loop = get_loop( n2_ctrl );
+IdealLoopTree *n3_loop = get_loop( n3_ctrl );
+// Does one of my inputs spin in a tighter loop than self?
+if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
+(n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
+(n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
+return NULL;                // Leave well enough alone
+// Is at least one of my inputs loop-invariant?
+if( n1_loop == n_loop &&
+n2_loop == n_loop &&
+n3_loop == n_loop )
+return NULL;                // No loop-invariant inputs
+int n_op = n->Opcode();
+// Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
+if( n_op == Op_LShiftI ) {
+// Scale is loop invariant
+Node *scale = n->in(2);
+Node *scale_ctrl = get_ctrl(scale);
+IdealLoopTree *scale_loop = get_loop(scale_ctrl );
+if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
+return NULL;
+const TypeInt *scale_t = scale->bottom_type()->isa_int();
+if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
+return NULL;              // Dont bother with byte/short masking
+// Add must vary with loop (else shift would be loop-invariant)
+Node *add = n->in(1);
+Node *add_ctrl = get_ctrl(add);
+IdealLoopTree *add_loop = get_loop(add_ctrl);
+//assert( n_loop == add_loop, "" );
+if( n_loop != add_loop ) return NULL;  // happens w/ evil ZKM loops
+// Convert I-V into I+ (0-V); same for V-I
+if( add->Opcode() == Op_SubI &&
+_igvn.type( add->in(1) ) != TypeInt::ZERO ) {
+Node *zero = _igvn.intcon(0);
+set_ctrl(zero, C->root());
+Node *neg = new (C, 3) SubINode( _igvn.intcon(0), add->in(2) );
+register_new_node( neg, get_ctrl(add->in(2) ) );
+add = new (C, 3) AddINode( add->in(1), neg );
+register_new_node( add, add_ctrl );
+}
+if( add->Opcode() != Op_AddI ) return NULL;
+// See if one add input is loop invariant
+Node *add_var = add->in(1);
+Node *add_var_ctrl = get_ctrl(add_var);
+IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
+Node *add_invar = add->in(2);
+Node *add_invar_ctrl = get_ctrl(add_invar);
+IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
+if( add_var_loop == n_loop ) {
+} else if( add_invar_loop == n_loop ) {
+// Swap to find the invariant part
+add_invar = add_var;
+add_invar_ctrl = add_var_ctrl;
+add_invar_loop = add_var_loop;
+add_var = add->in(2);
+Node *add_var_ctrl = get_ctrl(add_var);
+IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
+} else                      // Else neither input is loop invariant
+return NULL;
+if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
+return NULL;              // No invariant part of the add?
+// Yes!  Reshape address expression!
+Node *inv_scale = new (C, 3) LShiftINode( add_invar, scale );
+register_new_node( inv_scale, add_invar_ctrl );
+Node *var_scale = new (C, 3) LShiftINode( add_var, scale );
+register_new_node( var_scale, n_ctrl );
+Node *var_add = new (C, 3) AddINode( var_scale, inv_scale );
+register_new_node( var_add, n_ctrl );
+_igvn.hash_delete( n );
+_igvn.subsume_node( n, var_add );
+return var_add;
+}
+// Replace (I+V) with (V+I)
+if( n_op == Op_AddI ||
+n_op == Op_AddL ||
+n_op == Op_AddF ||
+n_op == Op_AddD ||
+n_op == Op_MulI ||
+n_op == Op_MulL ||
+n_op == Op_MulF ||
+n_op == Op_MulD ) {
+if( n2_loop == n_loop ) {
+assert( n1_loop != n_loop, "" );
+n->swap_edges(1, 2);
+}
+}
+// Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
+// but not if I2 is a constant.
+if( n_op == Op_AddP ) {
+if( n2_loop == n_loop && n3_loop != n_loop ) {
+if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
+Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
+Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
+IdealLoopTree *n22loop = get_loop( n22_ctrl );
+IdealLoopTree *n23_loop = get_loop( n23_ctrl );
+if( n22loop != n_loop && n22loop->is_member(n_loop) &&
+n23_loop == n_loop ) {
+Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
+// Stuff new AddP in the loop preheader
+register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
+Node *add2 = new (C, 4) AddPNode( n->in(1), add1, n->in(2)->in(3) );
+register_new_node( add2, n_ctrl );
+_igvn.hash_delete( n );
+_igvn.subsume_node( n, add2 );
+return add2;
+}
+}
+}
+// Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
+if( n2_loop != n_loop && n3_loop == n_loop ) {
+if( n->in(3)->Opcode() == Op_AddI ) {
+Node *V = n->in(3)->in(1);
+Node *I = n->in(3)->in(2);
+if( is_member(n_loop,get_ctrl(V)) ) {
+} else {
+Node *tmp = V; V = I; I = tmp;
+}
+if( !is_member(n_loop,get_ctrl(I)) ) {
+Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2), I );
+// Stuff new AddP in the loop preheader
+register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
+Node *add2 = new (C, 4) AddPNode( n->in(1), add1, V );
+register_new_node( add2, n_ctrl );
+_igvn.hash_delete( n );
+_igvn.subsume_node( n, add2 );
+return add2;
+}
+}
+}
+}
+return NULL;
+}
+//------------------------------conditional_move-------------------------------
+// Attempt to replace a Phi with a conditional move.  We have some pretty
+// strict profitability requirements.  All Phis at the merge point must
+// be converted, so we can remove the control flow.  We need to limit the
+// number of c-moves to a small handful.  All code that was in the side-arms
+// of the CFG diamond is now speculatively executed.  This code has to be
+// "cheap enough".  We are pretty much limited to CFG diamonds that merge
+// 1 or 2 items with a total of 1 or 2 ops executed speculatively.
+Node *PhaseIdealLoop::conditional_move( Node *region ) {
+assert( region->is_Region(), "sanity check" );
+if( region->req() != 3 ) return NULL;
+// Check for CFG diamond
+Node *lp = region->in(1);
+Node *rp = region->in(2);
+if( !lp || !rp ) return NULL;
+Node *lp_c = lp->in(0);
+if( lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If() ) return NULL;
+IfNode *iff = lp_c->as_If();
+// Check for highly predictable branch.  No point in CMOV'ing if
+// we are going to predict accurately all the time.
+// %%% This hides patterns produced by utility methods like Math.min.
+if( iff->_prob < PROB_UNLIKELY_MAG(3) ||
+iff->_prob > PROB_LIKELY_MAG(3) )
+return NULL;
+// Check for ops pinned in an arm of the diamond.
+// Can't remove the control flow in this case
+if( lp->outcnt() > 1 ) return NULL;
+if( rp->outcnt() > 1 ) return NULL;
+// Check profitability
+int cost = 0;
+for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
+Node *out = region->fast_out(i);
+if( !out->is_Phi() ) continue; // Ignore other control edges, etc
+PhiNode* phi = out->as_Phi();
+switch (phi->type()->basic_type()) {
+case T_LONG:
+cost++;                   // Probably encodes as 2 CMOV's
+case T_INT:                 // These all CMOV fine
+case T_FLOAT:
+case T_DOUBLE:
+case T_ADDRESS:             // (RawPtr)
+cost++;
+break;
+case T_OBJECT: {            // Base oops are OK, but not derived oops
+const TypeOopPtr *tp = phi->type()->isa_oopptr();
+// Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
+// CMOVE'd derived pointer?  It's a CMOVE'd derived base.  Thus
+// CMOVE'ing a derived pointer requires we also CMOVE the base.  If we
+// have a Phi for the base here that we convert to a CMOVE all is well
+// and good.  But if the base is dead, we'll not make a CMOVE.  Later
+// the allocator will have to produce a base by creating a CMOVE of the
+// relevant bases.  This puts the allocator in the business of
+// manufacturing expensive instructions, generally a bad plan.
+// Just Say No to Conditionally-Moved Derived Pointers.
+if( tp && tp->offset() != 0 )
+return NULL;
+cost++;
+break;
+}
+default:
+return NULL;              // In particular, can't do memory or I/O
+}
+// Add in cost any speculative ops
+for( uint j = 1; j < region->req(); j++ ) {
+Node *proj = region->in(j);
+Node *inp = phi->in(j);
+if (get_ctrl(inp) == proj) { // Found local op
+cost++;
+// Check for a chain of dependent ops; these will all become
+// speculative in a CMOV.
+for( uint k = 1; k < inp->req(); k++ )
+if (get_ctrl(inp->in(k)) == proj)
+return NULL;        // Too much speculative goo
+}
+}
+// See if the Phi is used by a Cmp.  This will likely Split-If, a
+// higher-payoff operation.
+for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
+Node* use = phi->fast_out(k);
+if( use->is_Cmp() )
+return NULL;
+}
+}
+if( cost >= ConditionalMoveLimit ) return NULL; // Too much goo
+// --------------
+// Now replace all Phis with CMOV's
+Node *cmov_ctrl = iff->in(0);
+uint flip = (lp->Opcode() == Op_IfTrue);
+while( 1 ) {
+PhiNode* phi = NULL;
+for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
+Node *out = region->fast_out(i);
+if (out->is_Phi()) {
+phi = out->as_Phi();
+break;
+}
+}
+if (phi == NULL)  break;
+#ifndef PRODUCT
+if( PrintOpto && VerifyLoopOptimizations ) tty->print_cr("CMOV");
+#endif
+// Move speculative ops
+for( uint j = 1; j < region->req(); j++ ) {
+Node *proj = region->in(j);
+Node *inp = phi->in(j);
+if (get_ctrl(inp) == proj) { // Found local op
+#ifndef PRODUCT
+if( PrintOpto && VerifyLoopOptimizations ) {
+tty->print("  speculate: ");
+inp->dump();
+}
+#endif
+set_ctrl(inp, cmov_ctrl);
+}
+}
+Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) );
+register_new_node( cmov, cmov_ctrl );
+_igvn.hash_delete(phi);
+_igvn.subsume_node( phi, cmov );
+#ifndef PRODUCT
+if( VerifyLoopOptimizations ) verify();
+#endif
+}
+// The useless CFG diamond will fold up later; see the optimization in
+// RegionNode::Ideal.
+_igvn._worklist.push(region);
+return iff->in(1);
+}
+//------------------------------split_if_with_blocks_pre-----------------------
+// Do the real work in a non-recursive function.  Data nodes want to be
+// cloned in the pre-order so they can feed each other nicely.
+Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
+// Cloning these guys is unlikely to win
+int n_op = n->Opcode();
+if( n_op == Op_MergeMem ) return n;
+if( n->is_Proj() ) return n;
+// Do not clone-up CmpFXXX variations, as these are always
+// followed by a CmpI
+if( n->is_Cmp() ) return n;
+// Attempt to use a conditional move instead of a phi/branch
+if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
+Node *cmov = conditional_move( n );
+if( cmov ) return cmov;
+}
+if( n->is_CFG() || n_op == Op_StorePConditional || n_op == Op_StoreLConditional || n_op == Op_CompareAndSwapI || n_op == Op_CompareAndSwapL ||n_op == Op_CompareAndSwapP)  return n;
+if( n_op == Op_Opaque1 ||     // Opaque nodes cannot be mod'd
+n_op == Op_Opaque2 ) {
+if( !C->major_progress() )   // If chance of no more loop opts...
+_igvn._worklist.push(n);  // maybe we'll remove them
+return n;
+}
+if( n->is_Con() ) return n;   // No cloning for Con nodes
+Node *n_ctrl = get_ctrl(n);
+if( !n_ctrl ) return n;       // Dead node
+// Attempt to remix address expressions for loop invariants
+Node *m = remix_address_expressions( n );
+if( m ) return m;
+// Determine if the Node has inputs from some local Phi.
+// Returns the block to clone thru.
+Node *n_blk = has_local_phi_input( n );
+if( !n_blk ) return n;
+// Do not clone the trip counter through on a CountedLoop
+// (messes up the canonical shape).
+if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
+// Check for having no control input; not pinned.  Allow
+// dominating control.
+if( n->in(0) ) {
+Node *dom = idom(n_blk);
+if( dom_lca( n->in(0), dom ) != n->in(0) )
+return n;
+}
+// Policy: when is it profitable.  You must get more wins than
+// policy before it is considered profitable.  Policy is usually 0,
+// so 1 win is considered profitable.  Big merges will require big
+// cloning, so get a larger policy.
+int policy = n_blk->req() >> 2;
+// If the loop is a candidate for range check elimination,
+// delay splitting through it's phi until a later loop optimization
+if (n_blk->is_CountedLoop()) {
+IdealLoopTree *lp = get_loop(n_blk);
+if (lp && lp->_rce_candidate) {
+return n;
+}
+}
+// Use same limit as split_if_with_blocks_post
+if( C->unique() > 35000 ) return n; // Method too big
+// Split 'n' through the merge point if it is profitable
+Node *phi = split_thru_phi( n, n_blk, policy );
+if( !phi ) return n;
+// Found a Phi to split thru!
+// Replace 'n' with the new phi
+_igvn.hash_delete(n);
+_igvn.subsume_node( n, phi );
+// Moved a load around the loop, 'en-registering' something.
+if( n_blk->Opcode() == Op_Loop && n->is_Load() &&
+!phi->in(LoopNode::LoopBackControl)->is_Load() )
+C->set_major_progress();
+return phi;
+}
+static bool merge_point_too_heavy(Compile* C, Node* region) {
+// Bail out if the region and its phis have too many users.
+int weight = 0;
+for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
+weight += region->fast_out(i)->outcnt();
+}
+int nodes_left = MaxNodeLimit - C->unique();
+if (weight * 8 > nodes_left) {
+#ifndef PRODUCT
+if (PrintOpto)
+tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
+#endif
+return true;
+} else {
+return false;
+}
+}
+#ifdef _LP64
+static bool merge_point_safe(Node* region) {
+// 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
+// having a PhiNode input. This sidesteps the dangerous case where the split
+// ConvI2LNode may become TOP if the input Value() does not
+// overlap the ConvI2L range, leaving a node which may not dominate its
+// uses.
+// A better fix for this problem can be found in the BugTraq entry, but
+// expediency for Mantis demands this hack.
+for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
+Node* n = region->fast_out(i);
+if (n->is_Phi()) {
+for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
+Node* m = n->fast_out(j);
+if (m->Opcode() == Op_ConvI2L) {
+return false;
+}
+}
+}
+}
+return true;
+}
+#endif
+//------------------------------place_near_use---------------------------------
+// Place some computation next to use but not inside inner loops.
+// For inner loop uses move it to the preheader area.
+Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
+IdealLoopTree *u_loop = get_loop( useblock );
+return (u_loop->_irreducible || u_loop->_child)
+? useblock
+: u_loop->_head->in(LoopNode::EntryControl);
+}
+//------------------------------split_if_with_blocks_post----------------------
+// Do the real work in a non-recursive function.  CFG hackery wants to be
+// in the post-order, so it can dirty the I-DOM info and not use the dirtied
+// info.
+void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
+// Cloning Cmp through Phi's involves the split-if transform.
+// FastLock is not used by an If
+if( n->is_Cmp() && !n->is_FastLock() ) {
+if( C->unique() > 35000 ) return; // Method too big
+// Do not do 'split-if' if irreducible loops are present.
+if( _has_irreducible_loops )
+return;
+Node *n_ctrl = get_ctrl(n);
+// Determine if the Node has inputs from some local Phi.
+// Returns the block to clone thru.
+Node *n_blk = has_local_phi_input( n );
+if( n_blk != n_ctrl ) return;
+if( merge_point_too_heavy(C, n_ctrl) )
+return;
+if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
+Node *bol = n->unique_out();
+assert( bol->is_Bool(), "expect a bool here" );
+if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
+Node *iff = bol->unique_out();
+// Check some safety conditions
+if( iff->is_If() ) {        // Classic split-if?
+if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
+} else if (iff->is_CMove()) { // Trying to split-up a CMOVE
+if( get_ctrl(iff->in(2)) == n_ctrl ||
+get_ctrl(iff->in(3)) == n_ctrl )
+return;                 // Inputs not yet split-up
+if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
+return;                 // Loop-invar test gates loop-varying CMOVE
+}
+} else {
+return;  // some other kind of node, such as an Allocate
+}
+// Do not do 'split-if' if some paths are dead.  First do dead code
+// elimination and then see if its still profitable.
+for( uint i = 1; i < n_ctrl->req(); i++ )
+if( n_ctrl->in(i) == C->top() )
+return;
+// When is split-if profitable?  Every 'win' on means some control flow
+// goes dead, so it's almost always a win.
+int policy = 0;
+// If trying to do a 'Split-If' at the loop head, it is only
+// profitable if the cmp folds up on BOTH paths.  Otherwise we
+// risk peeling a loop forever.
+// CNC - Disabled for now.  Requires careful handling of loop
+// body selection for the cloned code.  Also, make sure we check
+// for any input path not being in the same loop as n_ctrl.  For
+// irreducible loops we cannot check for 'n_ctrl->is_Loop()'
+// because the alternative loop entry points won't be converted
+// into LoopNodes.
+IdealLoopTree *n_loop = get_loop(n_ctrl);
+for( uint j = 1; j < n_ctrl->req(); j++ )
+if( get_loop(n_ctrl->in(j)) != n_loop )
+return;
+#ifdef _LP64
+// Check for safety of the merge point.
+if( !merge_point_safe(n_ctrl) ) {
+return;
+}
+#endif
+// Split compare 'n' through the merge point if it is profitable
+Node *phi = split_thru_phi( n, n_ctrl, policy );
+if( !phi ) return;
+// Found a Phi to split thru!
+// Replace 'n' with the new phi
+_igvn.hash_delete(n);
+_igvn.subsume_node( n, phi );
+// Now split the bool up thru the phi
+Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
+_igvn.hash_delete(bol);
+_igvn.subsume_node( bol, bolphi );
+assert( iff->in(1) == bolphi, "" );
+if( bolphi->Value(&_igvn)->singleton() )
+return;
+// Conditional-move?  Must split up now
+if( !iff->is_If() ) {
+Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
+_igvn.hash_delete(iff);
+_igvn.subsume_node( iff, cmovphi );
+return;
+}
+// Now split the IF
+do_split_if( iff );
+return;
+}
+// Check for an IF ready to split; one that has its
+// condition codes input coming from a Phi at the block start.
+int n_op = n->Opcode();
+// Check for an IF being dominated by another IF same test
+if( n_op == Op_If ) {
+Node *bol = n->in(1);
+uint max = bol->outcnt();
+// Check for same test used more than once?
+if( n_op == Op_If && max > 1 && bol->is_Bool() ) {
+// Search up IDOMs to see if this IF is dominated.
+Node *cutoff = get_ctrl(bol);
+// Now search up IDOMs till cutoff, looking for a dominating test
+Node *prevdom = n;
+Node *dom = idom(prevdom);
+while( dom != cutoff ) {
+if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) {
+// Replace the dominated test with an obvious true or false.
+// Place it on the IGVN worklist for later cleanup.
+C->set_major_progress();
+dominated_by( prevdom, n );
+#ifndef PRODUCT
+if( VerifyLoopOptimizations ) verify();
+#endif
+return;
+}
+prevdom = dom;
+dom = idom(prevdom);
+}
+}
+}
+// See if a shared loop-varying computation has no loop-varying uses.
+// Happens if something is only used for JVM state in uncommon trap exits,
+// like various versions of induction variable+offset.  Clone the
+// computation per usage to allow it to sink out of the loop.
+if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
+Node *n_ctrl = get_ctrl(n);
+IdealLoopTree *n_loop = get_loop(n_ctrl);
+if( n_loop != _ltree_root ) {
+DUIterator_Fast imax, i = n->fast_outs(imax);
+for (; i < imax; i++) {
+Node* u = n->fast_out(i);
+if( !has_ctrl(u) )     break; // Found control user
+IdealLoopTree *u_loop = get_loop(get_ctrl(u));
+if( u_loop == n_loop ) break; // Found loop-varying use
+if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
+if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
+}
+bool did_break = (i < imax);  // Did we break out of the previous loop?
+if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
+Node *late_load_ctrl;
+if (n->is_Load()) {
+// If n is a load, get and save the result from get_late_ctrl(),
+// to be later used in calculating the control for n's clones.
+clear_dom_lca_tags();
+late_load_ctrl = get_late_ctrl(n, n_ctrl);
+}
+// If n is a load, and the late control is the same as the current
+// control, then the cloning of n is a pointless exercise, because
+// GVN will ensure that we end up where we started.
+if (!n->is_Load() || late_load_ctrl != n_ctrl) {
+for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
+Node *u = n->last_out(j); // Clone private computation per use
+_igvn.hash_delete(u);
+_igvn._worklist.push(u);
+Node *x = n->clone(); // Clone computation
+Node *x_ctrl = NULL;
+if( u->is_Phi() ) {
+// Replace all uses of normal nodes.  Replace Phi uses
+// individually, so the seperate Nodes can sink down
+// different paths.
+uint k = 1;
+while( u->in(k) != n ) k++;
+u->set_req( k, x );
+// x goes next to Phi input path
+x_ctrl = u->in(0)->in(k);
+--j;
+} else {              // Normal use
+// Replace all uses
+for( uint k = 0; k < u->req(); k++ ) {
+if( u->in(k) == n ) {
+u->set_req( k, x );
+--j;
+}
+}
+x_ctrl = get_ctrl(u);
+}
+// Find control for 'x' next to use but not inside inner loops.
+// For inner loop uses get the preheader area.
+x_ctrl = place_near_use(x_ctrl);
+if (n->is_Load()) {
+// For loads, add a control edge to a CFG node outside of the loop
+// to force them to not combine and return back inside the loop
+// during GVN optimization (4641526).
+//
+// Because we are setting the actual control input, factor in
+// the result from get_late_ctrl() so we respect any
+// anti-dependences. (6233005).
+x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
+// Don't allow the control input to be a CFG splitting node.
+// Such nodes should only have ProjNodes as outs, e.g. IfNode
+// should only have IfTrueNode and IfFalseNode (4985384).
+x_ctrl = find_non_split_ctrl(x_ctrl);
+assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
+x->set_req(0, x_ctrl);
+}
+register_new_node(x, x_ctrl);
+// Some institutional knowledge is needed here: 'x' is
+// yanked because if the optimizer runs GVN on it all the
+// cloned x's will common up and undo this optimization and
+// be forced back in the loop.  This is annoying because it
+// makes +VerifyOpto report false-positives on progress.  I
+// tried setting control edges on the x's to force them to
+// not combine, but the matching gets worried when it tries
+// to fold a StoreP and an AddP together (as part of an
+// address expression) and the AddP and StoreP have
+// different controls.
+if( !x->is_Load() ) _igvn._worklist.yank(x);
+}
+_igvn.remove_dead_node(n);
+}
+}
+}
+}
+// Check for Opaque2's who's loop has disappeared - who's input is in the
+// same loop nest as their output.  Remove 'em, they are no longer useful.
+if( n_op == Op_Opaque2 &&
+n->in(1) != NULL &&
+get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
+_igvn.add_users_to_worklist(n);
+_igvn.hash_delete(n);
+_igvn.subsume_node( n, n->in(1) );
+}
+}
+//------------------------------split_if_with_blocks---------------------------
+// Check for aggressive application of 'split-if' optimization,
+// using basic block level info.
+void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
+Node *n = C->root();
+visited.set(n->_idx); // first, mark node as visited
+// Do pre-visit work for root
+n = split_if_with_blocks_pre( n );
+uint cnt = n->outcnt();
+uint i   = 0;
+while (true) {
+// Visit all children
+if (i < cnt) {
+Node* use = n->raw_out(i);
+++i;
+if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
+// Now do pre-visit work for this use
+use = split_if_with_blocks_pre( use );
+nstack.push(n, i); // Save parent and next use's index.
+n   = use;         // Process all children of current use.
+cnt = use->outcnt();
+i   = 0;
+}
+}
+else {
+// All of n's children have been processed, complete post-processing.
+if (cnt != 0 && !n->is_Con()) {
+assert(has_node(n), "no dead nodes");
+split_if_with_blocks_post( n );
+}
+if (nstack.is_empty()) {
+// Finished all nodes on stack.
+break;
+}
+// Get saved parent node and next use's index. Visit the rest of uses.
+n   = nstack.node();
+cnt = n->outcnt();
+i   = nstack.index();
+nstack.pop();
+}
+}
+}
+//=============================================================================
+//
+//                   C L O N E   A   L O O P   B O D Y
+//
+//------------------------------clone_iff--------------------------------------
+// Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
+// "Nearly" because all Nodes have been cloned from the original in the loop,
+// but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
+// through the Phi recursively, and return a Bool.
+BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
+// Convert this Phi into a Phi merging Bools
+uint i;
+for( i = 1; i < phi->req(); i++ ) {
+Node *b = phi->in(i);
+if( b->is_Phi() ) {
+_igvn.hash_delete(phi);
+_igvn._worklist.push(phi);
+phi->set_req(i, clone_iff( b->as_Phi(), loop ));
+} else {
+assert( b->is_Bool(), "" );
+}
+}
+Node *sample_bool = phi->in(1);
+Node *sample_cmp  = sample_bool->in(1);
+// Make Phis to merge the Cmp's inputs.
+int size = phi->in(0)->req();
+PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
+PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
+for( i = 1; i < phi->req(); i++ ) {
+Node *n1 = phi->in(i)->in(1)->in(1);
+Node *n2 = phi->in(i)->in(1)->in(2);
+phi1->set_req( i, n1 );
+phi2->set_req( i, n2 );
+phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
+phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
+}
+// See if these Phis have been made before.
+// Register with optimizer
+Node *hit1 = _igvn.hash_find_insert(phi1);
+if( hit1 ) {                  // Hit, toss just made Phi
+_igvn.remove_dead_node(phi1); // Remove new phi
+assert( hit1->is_Phi(), "" );
+phi1 = (PhiNode*)hit1;      // Use existing phi
+} else {                      // Miss
+_igvn.register_new_node_with_optimizer(phi1);
+}
+Node *hit2 = _igvn.hash_find_insert(phi2);
+if( hit2 ) {                  // Hit, toss just made Phi
+_igvn.remove_dead_node(phi2); // Remove new phi
+assert( hit2->is_Phi(), "" );
+phi2 = (PhiNode*)hit2;      // Use existing phi
+} else {                      // Miss
+_igvn.register_new_node_with_optimizer(phi2);
+}
+// Register Phis with loop/block info
+set_ctrl(phi1, phi->in(0));
+set_ctrl(phi2, phi->in(0));
+// Make a new Cmp
+Node *cmp = sample_cmp->clone();
+cmp->set_req( 1, phi1 );
+cmp->set_req( 2, phi2 );
+_igvn.register_new_node_with_optimizer(cmp);
+set_ctrl(cmp, phi->in(0));
+// Make a new Bool
+Node *b = sample_bool->clone();
+b->set_req(1,cmp);
+_igvn.register_new_node_with_optimizer(b);
+set_ctrl(b, phi->in(0));
+assert( b->is_Bool(), "" );
+return (BoolNode*)b;
+}
+//------------------------------clone_bool-------------------------------------
+// Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
+// "Nearly" because all Nodes have been cloned from the original in the loop,
+// but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
+// through the Phi recursively, and return a Bool.
+CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
+uint i;
+// Convert this Phi into a Phi merging Bools
+for( i = 1; i < phi->req(); i++ ) {
+Node *b = phi->in(i);
+if( b->is_Phi() ) {
+_igvn.hash_delete(phi);
+_igvn._worklist.push(phi);
+phi->set_req(i, clone_bool( b->as_Phi(), loop ));
+} else {
+assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
+}
+}
+Node *sample_cmp = phi->in(1);
+// Make Phis to merge the Cmp's inputs.
+int size = phi->in(0)->req();
+PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
+PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
+for( uint j = 1; j < phi->req(); j++ ) {
+Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
+Node *n1, *n2;
+if( cmp_top->is_Cmp() ) {
+n1 = cmp_top->in(1);
+n2 = cmp_top->in(2);
+} else {
+n1 = n2 = cmp_top;
+}
+phi1->set_req( j, n1 );
+phi2->set_req( j, n2 );
+phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
+phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
+}
+// See if these Phis have been made before.
+// Register with optimizer
+Node *hit1 = _igvn.hash_find_insert(phi1);
+if( hit1 ) {                  // Hit, toss just made Phi
+_igvn.remove_dead_node(phi1); // Remove new phi
+assert( hit1->is_Phi(), "" );
+phi1 = (PhiNode*)hit1;      // Use existing phi
+} else {                      // Miss
+_igvn.register_new_node_with_optimizer(phi1);
+}
+Node *hit2 = _igvn.hash_find_insert(phi2);
+if( hit2 ) {                  // Hit, toss just made Phi
+_igvn.remove_dead_node(phi2); // Remove new phi
+assert( hit2->is_Phi(), "" );
+phi2 = (PhiNode*)hit2;      // Use existing phi
+} else {                      // Miss
+_igvn.register_new_node_with_optimizer(phi2);
+}
+// Register Phis with loop/block info
+set_ctrl(phi1, phi->in(0));
+set_ctrl(phi2, phi->in(0));
+// Make a new Cmp
+Node *cmp = sample_cmp->clone();
+cmp->set_req( 1, phi1 );
+cmp->set_req( 2, phi2 );
+_igvn.register_new_node_with_optimizer(cmp);
+set_ctrl(cmp, phi->in(0));
+assert( cmp->is_Cmp(), "" );
+return (CmpNode*)cmp;
+}
+//------------------------------sink_use---------------------------------------
+// If 'use' was in the loop-exit block, it now needs to be sunk
+// below the post-loop merge point.
+void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
+if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
+set_ctrl(use, post_loop);
+for (DUIterator j = use->outs(); use->has_out(j); j++)
+sink_use(use->out(j), post_loop);
+}
+}
+//------------------------------clone_loop-------------------------------------
+//
+//                   C L O N E   A   L O O P   B O D Y
+//
+// This is the basic building block of the loop optimizations.  It clones an
+// entire loop body.  It makes an old_new loop body mapping; with this mapping
+// you can find the new-loop equivalent to an old-loop node.  All new-loop
+// nodes are exactly equal to their old-loop counterparts, all edges are the
+// same.  All exits from the old-loop now have a RegionNode that merges the
+// equivalent new-loop path.  This is true even for the normal "loop-exit"
+// condition.  All uses of loop-invariant old-loop values now come from (one
+// or more) Phis that merge their new-loop equivalents.
+//
+// This operation leaves the graph in an illegal state: there are two valid
+// control edges coming from the loop pre-header to both loop bodies.  I'll
+// definitely have to hack the graph after running this transform.
+//
+// From this building block I will further edit edges to perform loop peeling
+// or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
+//
+// Parameter side_by_size_idom:
+//   When side_by_size_idom is NULL, the dominator tree is constructed for
+//      the clone loop to dominate the original.  Used in construction of
+//      pre-main-post loop sequence.
+//   When nonnull, the clone and original are side-by-side, both are
+//      dominated by the side_by_side_idom node.  Used in construction of
+//      unswitched loops.
+void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
+Node* side_by_side_idom) {
+// Step 1: Clone the loop body.  Make the old->new mapping.
+uint i;
+for( i = 0; i < loop->_body.size(); i++ ) {
+Node *old = loop->_body.at(i);
+Node *nnn = old->clone();
+old_new.map( old->_idx, nnn );
+_igvn.register_new_node_with_optimizer(nnn);
+}
+// Step 2: Fix the edges in the new body.  If the old input is outside the
+// loop use it.  If the old input is INside the loop, use the corresponding
+// new node instead.
+for( i = 0; i < loop->_body.size(); i++ ) {
+Node *old = loop->_body.at(i);
+Node *nnn = old_new[old->_idx];
+// Fix CFG/Loop controlling the new node
+if (has_ctrl(old)) {
+set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
+} else {
+set_loop(nnn, loop->_parent);
+if (old->outcnt() > 0) {
+set_idom( nnn, old_new[idom(old)->_idx], dd );
+}
+}
+// Correct edges to the new node
+for( uint j = 0; j < nnn->req(); j++ ) {
+Node *n = nnn->in(j);
+if( n ) {
+IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
+if( loop->is_member( old_in_loop ) )
+nnn->set_req(j, old_new[n->_idx]);
+}
+}
+_igvn.hash_find_insert(nnn);
+}
+Node *newhead = old_new[loop->_head->_idx];
+set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
+// Step 3: Now fix control uses.  Loop varying control uses have already
+// been fixed up (as part of all input edges in Step 2).  Loop invariant
+// control uses must be either an IfFalse or an IfTrue.  Make a merge
+// point to merge the old and new IfFalse/IfTrue nodes; make the use
+// refer to this.
+ResourceArea *area = Thread::current()->resource_area();
+Node_List worklist(area);
+uint new_counter = C->unique();
+for( i = 0; i < loop->_body.size(); i++ ) {
+Node* old = loop->_body.at(i);
+if( !old->is_CFG() ) continue;
+Node* nnn = old_new[old->_idx];
+// Copy uses to a worklist, so I can munge the def-use info
+// with impunity.
+for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
+worklist.push(old->fast_out(j));
+while( worklist.size() ) {  // Visit all uses
+Node *use = worklist.pop();
+if (!has_node(use))  continue; // Ignore dead nodes
+IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
+if( !loop->is_member( use_loop ) && use->is_CFG() ) {
+// Both OLD and USE are CFG nodes here.
+assert( use->is_Proj(), "" );
+// Clone the loop exit control projection
+Node *newuse = use->clone();
+newuse->set_req(0,nnn);
+_igvn.register_new_node_with_optimizer(newuse);
+set_loop(newuse, use_loop);
+set_idom(newuse, nnn, dom_depth(nnn) + 1 );
+// We need a Region to merge the exit from the peeled body and the
+// exit from the old loop body.
+RegionNode *r = new (C, 3) RegionNode(3);
+// Map the old use to the new merge point
+old_new.map( use->_idx, r );
+uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
+assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
+// The original user of 'use' uses 'r' instead.
+for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
+Node* useuse = use->last_out(l);
+_igvn.hash_delete(useuse);
+_igvn._worklist.push(useuse);
+uint uses_found = 0;
+if( useuse->in(0) == use ) {
+useuse->set_req(0, r);
+uses_found++;
+if( useuse->is_CFG() ) {
+assert( dom_depth(useuse) > dd_r, "" );
+set_idom(useuse, r, dom_depth(useuse));
+}
+}
+for( uint k = 1; k < useuse->req(); k++ ) {
+if( useuse->in(k) == use ) {
+useuse->set_req(k, r);
+uses_found++;
+}
+}
+l -= uses_found;    // we deleted 1 or more copies of this edge
+}
+// Now finish up 'r'
+r->set_req( 1, newuse );
+r->set_req( 2,    use );
+_igvn.register_new_node_with_optimizer(r);
+set_loop(r, use_loop);
+set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
+} // End of if a loop-exit test
+}
+}
+// Step 4: If loop-invariant use is not control, it must be dominated by a
+// loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
+// there if needed.  Make a Phi there merging old and new used values.
+Node_List *split_if_set = NULL;
+Node_List *split_bool_set = NULL;
+Node_List *split_cex_set = NULL;
+for( i = 0; i < loop->_body.size(); i++ ) {
+Node* old = loop->_body.at(i);
+Node* nnn = old_new[old->_idx];
+// Copy uses to a worklist, so I can munge the def-use info
+// with impunity.
+for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
+worklist.push(old->fast_out(j));
+while( worklist.size() ) {
+Node *use = worklist.pop();
+if (!has_node(use))  continue; // Ignore dead nodes
+if (use->in(0) == C->top())  continue;
+IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
+// Check for data-use outside of loop - at least one of OLD or USE
+// must not be a CFG node.
+if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
+// If the Data use is an IF, that means we have an IF outside of the
+// loop that is switching on a condition that is set inside of the
+// loop.  Happens if people set a loop-exit flag; then test the flag
+// in the loop to break the loop, then test is again outside of the
+// loop to determine which way the loop exited.
+if( use->is_If() || use->is_CMove() ) {
+// Since this code is highly unlikely, we lazily build the worklist
+// of such Nodes to go split.
+if( !split_if_set )
+split_if_set = new Node_List(area);
+split_if_set->push(use);
+}
+if( use->is_Bool() ) {
+if( !split_bool_set )
+split_bool_set = new Node_List(area);
+split_bool_set->push(use);
+}
+if( use->Opcode() == Op_CreateEx ) {
+if( !split_cex_set )
+split_cex_set = new Node_List(area);
+split_cex_set->push(use);
+}
+// Get "block" use is in
+uint idx = 0;
+while( use->in(idx) != old ) idx++;
+Node *prev = use->is_CFG() ? use : get_ctrl(use);
+assert( !loop->is_member( get_loop( prev ) ), "" );
+Node *cfg = prev->_idx >= new_counter
+? prev->in(2)
+: idom(prev);
+if( use->is_Phi() )     // Phi use is in prior block
+cfg = prev->in(idx);  // NOT in block of Phi itself
+if (cfg->is_top()) {    // Use is dead?
+_igvn.hash_delete(use);
+_igvn._worklist.push(use);
+use->set_req(idx, C->top());
+continue;
+}
+while( !loop->is_member( get_loop( cfg ) ) ) {
+prev = cfg;
+cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
+}
+// If the use occurs after merging several exits from the loop, then
+// old value must have dominated all those exits.  Since the same old
+// value was used on all those exits we did not need a Phi at this
+// merge point.  NOW we do need a Phi here.  Each loop exit value
+// is now merged with the peeled body exit; each exit gets its own
+// private Phi and those Phis need to be merged here.
+Node *phi;
+if( prev->is_Region() ) {
+if( idx == 0 ) {      // Updating control edge?
+phi = prev;         // Just use existing control
+} else {              // Else need a new Phi
+phi = PhiNode::make( prev, old );
+// Now recursively fix up the new uses of old!
+for( uint i = 1; i < prev->req(); i++ ) {
+worklist.push(phi); // Onto worklist once for each 'old' input
+}
+}
+} else {
+// Get new RegionNode merging old and new loop exits
+prev = old_new[prev->_idx];
+assert( prev, "just made this in step 7" );
+if( idx == 0 ) {      // Updating control edge?
+phi = prev;         // Just use existing control
+} else {              // Else need a new Phi
+// Make a new Phi merging data values properly
+phi = PhiNode::make( prev, old );
+phi->set_req( 1, nnn );
+}
+}
+// If inserting a new Phi, check for prior hits
+if( idx != 0 ) {
+Node *hit = _igvn.hash_find_insert(phi);
+if( hit == NULL ) {
+_igvn.register_new_node_with_optimizer(phi); // Register new phi
+} else {                                      // or
+// Remove the new phi from the graph and use the hit
+_igvn.remove_dead_node(phi);
+phi = hit;                                  // Use existing phi
+}
+set_ctrl(phi, prev);
+}
+// Make 'use' use the Phi instead of the old loop body exit value
+_igvn.hash_delete(use);
+_igvn._worklist.push(use);
+use->set_req(idx, phi);
+if( use->_idx >= new_counter ) { // If updating new phis
+// Not needed for correctness, but prevents a weak assert
+// in AddPNode from tripping (when we end up with different
+// base & derived Phis that will become the same after
+// IGVN does CSE).
+Node *hit = _igvn.hash_find_insert(use);
+if( hit )             // Go ahead and re-hash for hits.
+_igvn.subsume_node( use, hit );
+}
+// If 'use' was in the loop-exit block, it now needs to be sunk
+// below the post-loop merge point.
+sink_use( use, prev );
+}
+}
+}
+// Check for IFs that need splitting/cloning.  Happens if an IF outside of
+// the loop uses a condition set in the loop.  The original IF probably
+// takes control from one or more OLD Regions (which in turn get from NEW
+// Regions).  In any case, there will be a set of Phis for each merge point
+// from the IF up to where the original BOOL def exists the loop.
+if( split_if_set ) {
+while( split_if_set->size() ) {
+Node *iff = split_if_set->pop();
+if( iff->in(1)->is_Phi() ) {
+BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
+_igvn.hash_delete(iff);
+_igvn._worklist.push(iff);
+iff->set_req(1, b);
+}
+}
+}
+if( split_bool_set ) {
+while( split_bool_set->size() ) {
+Node *b = split_bool_set->pop();
+Node *phi = b->in(1);
+assert( phi->is_Phi(), "" );
+CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
+_igvn.hash_delete(b);
+_igvn._worklist.push(b);
+b->set_req(1, cmp);
+}
+}
+if( split_cex_set ) {
+while( split_cex_set->size() ) {
+Node *b = split_cex_set->pop();
+assert( b->in(0)->is_Region(), "" );
+assert( b->in(1)->is_Phi(), "" );
+assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
+split_up( b, b->in(0), NULL );
+}
+}
+}
+//---------------------- stride_of_possible_iv -------------------------------------
+// Looks for an iff/bool/comp with one operand of the compare
+// being a cycle involving an add and a phi,
+// with an optional truncation (left-shift followed by a right-shift)
+// of the add. Returns zero if not an iv.
+int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
+Node* trunc1 = NULL;
+Node* trunc2 = NULL;
+const TypeInt* ttype = NULL;
+if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
+return 0;
+}
+BoolNode* bl = iff->in(1)->as_Bool();
+Node* cmp = bl->in(1);
+if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
+return 0;
+}
+// Must have an invariant operand
+if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
+return 0;
+}
+Node* add2 = NULL;
+Node* cmp1 = cmp->in(1);
+if (cmp1->is_Phi()) {
+// (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
+Node* phi = cmp1;
+for (uint i = 1; i < phi->req(); i++) {
+Node* in = phi->in(i);
+Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
+&trunc1, &trunc2, &ttype);
+if (add && add->in(1) == phi) {
+add2 = add->in(2);
+break;
+}
+}
+} else {
+// (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
+Node* addtrunc = cmp1;
+Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
+&trunc1, &trunc2, &ttype);
+if (add && add->in(1)->is_Phi()) {
+Node* phi = add->in(1);
+for (uint i = 1; i < phi->req(); i++) {
+if (phi->in(i) == addtrunc) {
+add2 = add->in(2);
+break;
+}
+}
+}
+}
+if (add2 != NULL) {
+const TypeInt* add2t = _igvn.type(add2)->is_int();
+if (add2t->is_con()) {
+return add2t->get_con();
+}
+}
+return 0;
+}
+//---------------------- stay_in_loop -------------------------------------
+// Return the (unique) control output node that's in the loop (if it exists.)
+Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
+Node* unique = NULL;
+if (!n) return NULL;
+for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+Node* use = n->fast_out(i);
+if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
+if (unique != NULL) {
+return NULL;
+}
+unique = use;
+}
+}
+return unique;
+}
+//------------------------------ register_node -------------------------------------
+// Utility to register node "n" with PhaseIdealLoop
+void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
+_igvn.register_new_node_with_optimizer(n);
+loop->_body.push(n);
+if (n->is_CFG()) {
+set_loop(n, loop);
+set_idom(n, pred, ddepth);
+} else {
+set_ctrl(n, pred);
+}
+}
+//------------------------------ proj_clone -------------------------------------
+// Utility to create an if-projection
+ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
+ProjNode* c = p->clone()->as_Proj();
+c->set_req(0, iff);
+return c;
+}
+//------------------------------ short_circuit_if -------------------------------------
+// Force the iff control output to be the live_proj
+Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
+int proj_con = live_proj->_con;
+assert(proj_con == 0 || proj_con == 1, "false or true projection");
+Node *con = _igvn.intcon(proj_con);
+set_ctrl(con, C->root());
+if (iff) {
+iff->set_req(1, con);
+}
+return con;
+}
+//------------------------------ insert_if_before_proj -------------------------------------
+// Insert a new if before an if projection (* - new node)
+//
+// before
+//           if(test)
+//           /     \
+//          v       v
+//    other-proj   proj (arg)
+//
+// after
+//           if(test)
+//           /     \
+//          /       v
+//         |      * proj-clone
+//         v          |
+//    other-proj      v
+//                * new_if(relop(cmp[IU](left,right)))
+//                  /  \
+//                 v    v
+//         * new-proj  proj
+//         (returned)
+//
+ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
+IfNode* iff = proj->in(0)->as_If();
+IdealLoopTree *loop = get_loop(proj);
+ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
+int ddepth = dom_depth(proj);
+_igvn.hash_delete(iff);
+_igvn._worklist.push(iff);
+_igvn.hash_delete(proj);
+_igvn._worklist.push(proj);
+proj->set_req(0, NULL);  // temporary disconnect
+ProjNode* proj2 = proj_clone(proj, iff);
+register_node(proj2, loop, iff, ddepth);
+Node* cmp = Signed ? (Node*) new (C,3)CmpINode(left, right) : (Node*) new (C,3)CmpUNode(left, right);
+register_node(cmp, loop, proj2, ddepth);
+BoolNode* bol = new (C,2)BoolNode(cmp, relop);
+register_node(bol, loop, proj2, ddepth);
+IfNode* new_if = new (C,2)IfNode(proj2, bol, iff->_prob, iff->_fcnt);
+register_node(new_if, loop, proj2, ddepth);
+proj->set_req(0, new_if); // reattach
+set_idom(proj, new_if, ddepth);
+ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
+register_node(new_exit, get_loop(other_proj), new_if, ddepth);
+return new_exit;
+}
+//------------------------------ insert_region_before_proj -------------------------------------
+// Insert a region before an if projection (* - new node)
+//
+// before
+//           if(test)
+//          /      |
+//         v       |
+//       proj      v
+//               other-proj
+//
+// after
+//           if(test)
+//          /      |
+//         v       |
+// * proj-clone    v
+//         |     other-proj
+//         v
+// * new-region
+//         |
+//         v
+// *      dum_if
+//       /     \
+//      v       \
+// * dum-proj    v
+//              proj
+//
+RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
+IfNode* iff = proj->in(0)->as_If();
+IdealLoopTree *loop = get_loop(proj);
+ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
+int ddepth = dom_depth(proj);
+_igvn.hash_delete(iff);
+_igvn._worklist.push(iff);
+_igvn.hash_delete(proj);
+_igvn._worklist.push(proj);
+proj->set_req(0, NULL);  // temporary disconnect
+ProjNode* proj2 = proj_clone(proj, iff);
+register_node(proj2, loop, iff, ddepth);
+RegionNode* reg = new (C,2)RegionNode(2);
+reg->set_req(1, proj2);
+register_node(reg, loop, iff, ddepth);
+IfNode* dum_if = new (C,2)IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
+register_node(dum_if, loop, reg, ddepth);
+proj->set_req(0, dum_if); // reattach
+set_idom(proj, dum_if, ddepth);
+ProjNode* dum_proj = proj_clone(other_proj, dum_if);
+register_node(dum_proj, loop, dum_if, ddepth);
+return reg;
+}
+//------------------------------ insert_cmpi_loop_exit -------------------------------------
+// Clone a signed compare loop exit from an unsigned compare and
+// insert it before the unsigned cmp on the stay-in-loop path.
+// All new nodes inserted in the dominator tree between the original
+// if and it's projections.  The original if test is replaced with
+// a constant to force the stay-in-loop path.
+//
+// This is done to make sure that the original if and it's projections
+// still dominate the same set of control nodes, that the ctrl() relation
+// from data nodes to them is preserved, and that their loop nesting is
+// preserved.
+//
+// before
+//          if(i <u limit)    unsigned compare loop exit
+//         /       |
+//        v        v
+//   exit-proj   stay-in-loop-proj
+//
+// after
+//          if(stay-in-loop-const)  original if
+//         /       |
+//        /        v
+//       /  if(i <  limit)    new signed test
+//      /  /       |
+//     /  /        v
+//    /  /  if(i <u limit)    new cloned unsigned test
+//   /  /   /      |
+//   v  v  v       |
+//    region       |
+//        |        |
+//      dum-if     |
+//     /  |        |
+// ether  |        |
+//        v        v
+//   exit-proj   stay-in-loop-proj
+//
+IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
+const bool Signed   = true;
+const bool Unsigned = false;
+BoolNode* bol = if_cmpu->in(1)->as_Bool();
+if (bol->_test._test != BoolTest::lt) return NULL;
+CmpNode* cmpu = bol->in(1)->as_Cmp();
+if (cmpu->Opcode() != Op_CmpU) return NULL;
+int stride = stride_of_possible_iv(if_cmpu);
+if (stride == 0) return NULL;
+ProjNode* lp_continue = stay_in_loop(if_cmpu, loop)->as_Proj();
+ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
+Node* limit = NULL;
+if (stride > 0) {
+limit = cmpu->in(2);
+} else {
+limit = _igvn.makecon(TypeInt::ZERO);
+set_ctrl(limit, C->root());
+}
+// Create a new region on the exit path
+RegionNode* reg = insert_region_before_proj(lp_exit);
+// Clone the if-cmpu-true-false using a signed compare
+BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
+ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
+reg->add_req(cmpi_exit);
+// Clone the if-cmpu-true-false
+BoolTest::mask rel_u = bol->_test._test;
+ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
+reg->add_req(cmpu_exit);
+// Force original if to stay in loop.
+short_circuit_if(if_cmpu, lp_continue);
+return cmpi_exit->in(0)->as_If();
+}
+//------------------------------ remove_cmpi_loop_exit -------------------------------------
+// Remove a previously inserted signed compare loop exit.
+void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
+Node* lp_proj = stay_in_loop(if_cmp, loop);
+assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
+stay_in_loop(lp_proj, loop)->is_If() &&
+stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
+Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
+set_ctrl(con, C->root());
+if_cmp->set_req(1, con);
+}
+//------------------------------ scheduled_nodelist -------------------------------------
+// Create a post order schedule of nodes that are in the
+// "member" set.  The list is returned in "sched".
+// The first node in "sched" is the loop head, followed by
+// nodes which have no inputs in the "member" set, and then
+// followed by the nodes that have an immediate input dependence
+// on a node in "sched".
+void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
+assert(member.test(loop->_head->_idx), "loop head must be in member set");
+Arena *a = Thread::current()->resource_area();
+VectorSet visited(a);
+Node_Stack nstack(a, loop->_body.size());
+Node* n  = loop->_head;  // top of stack is cached in "n"
+uint idx = 0;
+visited.set(n->_idx);
+// Initially push all with no inputs from within member set
+for(uint i = 0; i < loop->_body.size(); i++ ) {
+Node *elt = loop->_body.at(i);
+if (member.test(elt->_idx)) {
+bool found = false;
+for (uint j = 0; j < elt->req(); j++) {
+Node* def = elt->in(j);
+if (def && member.test(def->_idx) && def != elt) {
+found = true;
+break;
+}
+}
+if (!found && elt != loop->_head) {
+nstack.push(n, idx);
+n = elt;
+assert(!visited.test(n->_idx), "not seen yet");
+visited.set(n->_idx);
+}
+}
+}
+// traverse out's that are in the member set
+while (true) {
+if (idx < n->outcnt()) {
+Node* use = n->raw_out(idx);
+idx++;
+if (!visited.test_set(use->_idx)) {
+if (member.test(use->_idx)) {
+nstack.push(n, idx);
+n = use;
+idx = 0;
+}
+}
+} else {
+// All outputs processed
+sched.push(n);
+if (nstack.is_empty()) break;
+n   = nstack.node();
+idx = nstack.index();
+nstack.pop();
+}
+}
+}
+//------------------------------ has_use_in_set -------------------------------------
+// Has a use in the vector set
+bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
+for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
+Node* use = n->fast_out(j);
+if (vset.test(use->_idx)) {
+return true;
+}
+}
+return false;
+}
+//------------------------------ has_use_internal_to_set -------------------------------------
+// Has use internal to the vector set (ie. not in a phi at the loop head)
+bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
+Node* head  = loop->_head;
+for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
+Node* use = n->fast_out(j);
+if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
+return true;
+}
+}
+return false;
+}
+//------------------------------ clone_for_use_outside_loop -------------------------------------
+// clone "n" for uses that are outside of loop
+void PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
+assert(worklist.size() == 0, "should be empty");
+for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
+Node* use = n->fast_out(j);
+if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
+worklist.push(use);
+}
+}
+while( worklist.size() ) {
+Node *use = worklist.pop();
+if (!has_node(use) || use->in(0) == C->top()) continue;
+uint j;
+for (j = 0; j < use->req(); j++) {
+if (use->in(j) == n) break;
+}
+assert(j < use->req(), "must be there");
+// clone "n" and insert it between the inputs of "n" and the use outside the loop
+Node* n_clone = n->clone();
+_igvn.hash_delete(use);
+use->set_req(j, n_clone);
+_igvn._worklist.push(use);
+if (!use->is_Phi()) {
+Node* use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
+set_ctrl(n_clone, use_c);
+assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
+get_loop(use_c)->_body.push(n_clone);
+} else {
+// Use in a phi is considered a use in the associated predecessor block
+Node *prevbb = use->in(0)->in(j);
+set_ctrl(n_clone, prevbb);
+assert(!loop->is_member(get_loop(prevbb)), "should be outside loop");
+get_loop(prevbb)->_body.push(n_clone);
+}
+_igvn.register_new_node_with_optimizer(n_clone);
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
+}
+#endif
+}
+}
+//------------------------------ clone_for_special_use_inside_loop -------------------------------------
+// clone "n" for special uses that are in the not_peeled region.
+// If these def-uses occur in separate blocks, the code generator
+// marks the method as not compilable.  For example, if a "BoolNode"
+// is in a different basic block than the "IfNode" that uses it, then
+// the compilation is aborted in the code generator.
+void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
+VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
+if (n->is_Phi() || n->is_Load()) {
+return;
+}
+assert(worklist.size() == 0, "should be empty");
+for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
+Node* use = n->fast_out(j);
+if ( not_peel.test(use->_idx) &&
+(use->is_If() || use->is_CMove() || use->is_Bool()) &&
+use->in(1) == n)  {
+worklist.push(use);
+}
+}
+if (worklist.size() > 0) {
+// clone "n" and insert it between inputs of "n" and the use
+Node* n_clone = n->clone();
+loop->_body.push(n_clone);
+_igvn.register_new_node_with_optimizer(n_clone);
+set_ctrl(n_clone, get_ctrl(n));
+sink_list.push(n_clone);
+not_peel <<= n_clone->_idx;  // add n_clone to not_peel set.
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
+}
+#endif
+while( worklist.size() ) {
+Node *use = worklist.pop();
+_igvn.hash_delete(use);
+_igvn._worklist.push(use);
+for (uint j = 1; j < use->req(); j++) {
+if (use->in(j) == n) {
+use->set_req(j, n_clone);
+}
+}
+}
+}
+}
+//------------------------------ insert_phi_for_loop -------------------------------------
+// Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
+void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
+Node *phi = PhiNode::make(lp, back_edge_val);
+phi->set_req(LoopNode::EntryControl, lp_entry_val);
+// Use existing phi if it already exists
+Node *hit = _igvn.hash_find_insert(phi);
+if( hit == NULL ) {
+_igvn.register_new_node_with_optimizer(phi);
+set_ctrl(phi, lp);
+} else {
+// Remove the new phi from the graph and use the hit
+_igvn.remove_dead_node(phi);
+phi = hit;
+}
+_igvn.hash_delete(use);
+_igvn._worklist.push(use);
+use->set_req(idx, phi);
+}
+#ifdef ASSERT
+//------------------------------ is_valid_loop_partition -------------------------------------
+// Validate the loop partition sets: peel and not_peel
+bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
+VectorSet& not_peel ) {
+uint i;
+// Check that peel_list entries are in the peel set
+for (i = 0; i < peel_list.size(); i++) {
+if (!peel.test(peel_list.at(i)->_idx)) {
+return false;
+}
+}
+// Check at loop members are in one of peel set or not_peel set
+for (i = 0; i < loop->_body.size(); i++ ) {
+Node *def  = loop->_body.at(i);
+uint di = def->_idx;
+// Check that peel set elements are in peel_list
+if (peel.test(di)) {
+if (not_peel.test(di)) {
+return false;
+}
+// Must be in peel_list also
+bool found = false;
+for (uint j = 0; j < peel_list.size(); j++) {
+if (peel_list.at(j)->_idx == di) {
+found = true;
+break;
+}
+}
+if (!found) {
+return false;
+}
+} else if (not_peel.test(di)) {
+if (peel.test(di)) {
+return false;
+}
+} else {
+return false;
+}
+}
+return true;
+}
+//------------------------------ is_valid_clone_loop_exit_use -------------------------------------
+// Ensure a use outside of loop is of the right form
+bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
+Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
+return (use->is_Phi() &&
+use_c->is_Region() && use_c->req() == 3 &&
+(use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
+use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
+use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
+loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
+}
+//------------------------------ is_valid_clone_loop_form -------------------------------------
+// Ensure that all uses outside of loop are of the right form
+bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
+uint orig_exit_idx, uint clone_exit_idx) {
+uint len = peel_list.size();
+for (uint i = 0; i < len; i++) {
+Node *def = peel_list.at(i);
+for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
+Node *use = def->fast_out(j);
+Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
+if (!loop->is_member(get_loop(use_c))) {
+// use is not in the loop, check for correct structure
+if (use->in(0) == def) {
+// Okay
+} else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
+return false;
+}
+}
+}
+}
+return true;
+}
+#endif
+//------------------------------ partial_peel -------------------------------------
+// Partially peel (aka loop rotation) the top portion of a loop (called
+// the peel section below) by cloning it and placing one copy just before
+// the new loop head and the other copy at the bottom of the new loop.
+//
+//    before                       after                where it came from
+//
+//    stmt1                        stmt1
+//  loop:                          stmt2                     clone
+//    stmt2                        if condA goto exitA       clone
+//    if condA goto exitA        new_loop:                   new
+//    stmt3                        stmt3                     clone
+//    if !condB goto loop          if condB goto exitB       clone
+//  exitB:                         stmt2                     orig
+//    stmt4                        if !condA goto new_loop   orig
+//  exitA:                         goto exitA
+//                               exitB:
+//                                 stmt4
+//                               exitA:
+//
+// Step 1: find the cut point: an exit test on probable
+//         induction variable.
+// Step 2: schedule (with cloning) operations in the peel
+//         section that can be executed after the cut into
+//         the section that is not peeled.  This may need
+//         to clone operations into exit blocks.  For
+//         instance, a reference to A[i] in the not-peel
+//         section and a reference to B[i] in an exit block
+//         may cause a left-shift of i by 2 to be placed
+//         in the peel block.  This step will clone the left
+//         shift into the exit block and sink the left shift
+//         from the peel to the not-peel section.
+// Step 3: clone the loop, retarget the control, and insert
+//         phis for values that are live across the new loop
+//         head.  This is very dependent on the graph structure
+//         from clone_loop.  It creates region nodes for
+//         exit control and associated phi nodes for values
+//         flow out of the loop through that exit.  The region
+//         node is dominated by the clone's control projection.
+//         So the clone's peel section is placed before the
+//         new loop head, and the clone's not-peel section is
+//         forms the top part of the new loop.  The original
+//         peel section forms the tail of the new loop.
+// Step 4: update the dominator tree and recompute the
+//         dominator depth.
+//
+//                   orig
+//
+//                  stmt1
+//                    |
+//                    v
+//                   loop<----+
+//                     |      |
+//                   stmt2    |
+//                     |      |
+//                     v      |
+//                    ifA     |
+//                   / |      |
+//                  v  v      |
+//               false true   ^  <-- last_peel
+//               /     |      |
+//              /   ===|==cut |
+//             /     stmt3    |  <-- first_not_peel
+//            /        |      |
+//            |        v      |
+//            v       ifB     |
+//          exitA:   / \      |
+//                  /   \     |
+//                 v     v    |
+//               false true   |
+//               /       \    |
+//              /         ----+
+//             |
+//             v
+//           exitB:
+//           stmt4
+//
+//
+//            after clone loop
+//
+//                   stmt1
+//                 /       \
+//        clone   /         \   orig
+//               /           \
+//              /             \
+//             v               v
+//   +---->loop                loop<----+
+//   |      |                    |      |
+//   |    stmt2                stmt2    |
+//   |      |                    |      |
+//   |      v                    v      |
+//   |      ifA                 ifA     |
+//   |      | \                / |      |
+//   |      v  v              v  v      |
+//   ^    true  false      false true   ^  <-- last_peel
+//   |      |   ^   \       /    |      |
+//   | cut==|==  \   \     /  ===|==cut |
+//   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
+//   |      |    dom   | |       |      |
+//   |      v      \  1v v2      v      |
+//   |      ifB     regionA     ifB     |
+//   |      / \        |       / \      |
+//   |     /   \       v      /   \     |
+//   |    v     v    exitA:  v     v    |
+//   |    true  false      false true   |
+//   |    /     ^   \      /       \    |
+//   +----       \   \    /         ----+
+//               dom  \  /
+//                 \  1v v2
+//                  regionB
+//                     |
+//                     v
+//                   exitB:
+//                   stmt4
+//
+//
+//           after partial peel
+//
+//                  stmt1
+//                 /
+//        clone   /             orig
+//               /          TOP
+//              /             \
+//             v               v
+//    TOP->region             region----+
+//          |                    |      |
+//        stmt2                stmt2    |
+//          |                    |      |
+//          v                    v      |
+//          ifA                 ifA     |
+//          | \                / |      |
+//          v  v              v  v      |
+//        true  false      false true   |     <-- last_peel
+//          |   ^   \       /    +------|---+
+//  +->newloop   \   \     /  === ==cut |   |
+//  |     stmt3   \   \   /     TOP     |   |
+//  |       |    dom   | |      stmt3   |   | <-- first_not_peel
+//  |       v      \  1v v2      v      |   |
+//  |       ifB     regionA     ifB     ^   v
+//  |       / \        |       / \      |   |
+//  |      /   \       v      /   \     |   |
+//  |     v     v    exitA:  v     v    |   |
+//  |     true  false      false true   |   |
+//  |     /     ^   \      /       \    |   |
+//  |    |       \   \    /         v   |   |
+//  |    |       dom  \  /         TOP  |   |
+//  |    |         \  1v v2             |   |
+//  ^    v          regionB             |   |
+//  |    |             |                |   |
+//  |    |             v                ^   v
+//  |    |           exitB:             |   |
+//  |    |           stmt4              |   |
+//  |    +------------>-----------------+   |
+//  |                                       |
+//  +-----------------<---------------------+
+//
+//
+//              final graph
+//
+//                  stmt1
+//                    |
+//                    v
+//         ........> ifA clone
+//         :        / |
+//        dom      /  |
+//         :      v   v
+//         :  false   true
+//         :  |       |
+//         :  |     stmt2 clone
+//         :  |       |
+//         :  |       v
+//         :  |    newloop<-----+
+//         :  |        |        |
+//         :  |     stmt3 clone |
+//         :  |        |        |
+//         :  |        v        |
+//         :  |       ifB       |
+//         :  |      / \        |
+//         :  |     v   v       |
+//         :  |  false true     |
+//         :  |   |     |       |
+//         :  |   v    stmt2    |
+//         :  | exitB:  |       |
+//         :  | stmt4   v       |
+//         :  |       ifA orig  |
+//         :  |      /  \       |
+//         :  |     /    \      |
+//         :  |    v     v      |
+//         :  |  false  true    |
+//         :  |  /        \     |
+//         :  v  v         -----+
+//          RegionA
+//             |
+//             v
+//           exitA
+//
+bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
+LoopNode *head  = loop->_head->as_Loop();
+if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
+return false;
+}
+// Check for complex exit control
+for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
+Node *n = loop->_body.at(ii);
+int opc = n->Opcode();
+if (n->is_Call()        ||
+opc == Op_Catch     ||
+opc == Op_CatchProj ||
+opc == Op_Jump      ||
+opc == Op_JumpProj) {
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
+}
+#endif
+return false;
+}
+}
+int dd = dom_depth(head);
+// Step 1: find cut point
+// Walk up dominators to loop head looking for first loop exit
+// which is executed on every path thru loop.
+IfNode *peel_if = NULL;
+IfNode *peel_if_cmpu = NULL;
+Node *iff = loop->tail();
+while( iff != head ) {
+if( iff->is_If() ) {
+Node *ctrl = get_ctrl(iff->in(1));
+if (ctrl->is_top()) return false; // Dead test on live IF.
+// If loop-varying exit-test, check for induction variable
+if( loop->is_member(get_loop(ctrl)) &&
+loop->is_loop_exit(iff) &&
+is_possible_iv_test(iff)) {
+Node* cmp = iff->in(1)->in(1);
+if (cmp->Opcode() == Op_CmpI) {
+peel_if = iff->as_If();
+} else {
+assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
+peel_if_cmpu = iff->as_If();
+}
+}
+}
+iff = idom(iff);
+}
+// Prefer signed compare over unsigned compare.
+IfNode* new_peel_if = NULL;
+if (peel_if == NULL) {
+if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
+return false;   // No peel point found
+}
+new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
+if (new_peel_if == NULL) {
+return false;   // No peel point found
+}
+peel_if = new_peel_if;
+}
+Node* last_peel        = stay_in_loop(peel_if, loop);
+Node* first_not_peeled = stay_in_loop(last_peel, loop);
+if (first_not_peeled == NULL || first_not_peeled == head) {
+return false;
+}
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("before partial peel one iteration");
+Node_List wl;
+Node* t = head->in(2);
+while (true) {
+wl.push(t);
+if (t == head) break;
+t = idom(t);
+}
+while (wl.size() > 0) {
+Node* tt = wl.pop();
+tt->dump();
+if (tt == last_peel) tty->print_cr("-- cut --");
+}
+}
+#endif
+ResourceArea *area = Thread::current()->resource_area();
+VectorSet peel(area);
+VectorSet not_peel(area);
+Node_List peel_list(area);
+Node_List worklist(area);
+Node_List sink_list(area);
+// Set of cfg nodes to peel are those that are executable from
+// the head through last_peel.
+assert(worklist.size() == 0, "should be empty");
+worklist.push(head);
+peel.set(head->_idx);
+while (worklist.size() > 0) {
+Node *n = worklist.pop();
+if (n != last_peel) {
+for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
+Node* use = n->fast_out(j);
+if (use->is_CFG() &&
+loop->is_member(get_loop(use)) &&
+!peel.test_set(use->_idx)) {
+worklist.push(use);
+}
+}
+}
+}
+// Set of non-cfg nodes to peel are those that are control
+// dependent on the cfg nodes.
+uint i;
+for(i = 0; i < loop->_body.size(); i++ ) {
+Node *n = loop->_body.at(i);
+Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
+if (peel.test(n_c->_idx)) {
+peel.set(n->_idx);
+} else {
+not_peel.set(n->_idx);
+}
+}
+// Step 2: move operations from the peeled section down into the
+//         not-peeled section
+// Get a post order schedule of nodes in the peel region
+// Result in right-most operand.
+scheduled_nodelist(loop, peel, peel_list );
+assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
+// For future check for too many new phis
+uint old_phi_cnt = 0;
+for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
+Node* use = head->fast_out(j);
+if (use->is_Phi()) old_phi_cnt++;
+}
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("\npeeled list");
+}
+#endif
+// Evacuate nodes in peel region into the not_peeled region if possible
+uint new_phi_cnt = 0;
+for (i = 0; i < peel_list.size();) {
+Node* n = peel_list.at(i);
+#if !defined(PRODUCT)
+if (TracePartialPeeling) n->dump();
+#endif
+bool incr = true;
+if ( !n->is_CFG() ) {
+if ( has_use_in_set(n, not_peel) ) {
+// If not used internal to the peeled region,
+// move "n" from peeled to not_peeled region.
+if ( !has_use_internal_to_set(n, peel, loop) ) {
+// if not pinned and not a load (which maybe anti-dependent on a store)
+// and not a CMove (Matcher expects only bool->cmove).
+if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
+clone_for_use_outside_loop( loop, n, worklist );
+sink_list.push(n);
+peel     >>= n->_idx; // delete n from peel set.
+not_peel <<= n->_idx; // add n to not_peel set.
+peel_list.remove(i);
+incr = false;
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("sink to not_peeled region: %d newbb: %d",
+n->_idx, get_ctrl(n)->_idx);
+}
+#endif
+}
+} else {
+// Otherwise check for special def-use cases that span
+// the peel/not_peel boundary such as bool->if
+clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
+new_phi_cnt++;
+}
+}
+}
+if (incr) i++;
+}
+if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
+new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
+}
+#endif
+if (new_peel_if != NULL) {
+remove_cmpi_loop_exit(new_peel_if, loop);
+}
+// Inhibit more partial peeling on this loop
+assert(!head->is_partial_peel_loop(), "not partial peeled");
+head->mark_partial_peel_failed();
+return false;
+}
+// Step 3: clone loop, retarget control, and insert new phis
+// Create new loop head for new phis and to hang
+// the nodes being moved (sinked) from the peel region.
+LoopNode* new_head = new (C, 3) LoopNode(last_peel, last_peel);
+_igvn.register_new_node_with_optimizer(new_head);
+assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
+first_not_peeled->set_req(0, new_head);
+set_loop(new_head, loop);
+loop->_body.push(new_head);
+not_peel.set(new_head->_idx);
+set_idom(new_head, last_peel, dom_depth(first_not_peeled));
+set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
+while (sink_list.size() > 0) {
+Node* n = sink_list.pop();
+set_ctrl(n, new_head);
+}
+assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
+clone_loop( loop, old_new, dd );
+const uint clone_exit_idx = 1;
+const uint orig_exit_idx  = 2;
+assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
+Node* head_clone             = old_new[head->_idx];
+LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
+Node* orig_tail_clone        = head_clone->in(2);
+// Add phi if "def" node is in peel set and "use" is not
+for(i = 0; i < peel_list.size(); i++ ) {
+Node *def  = peel_list.at(i);
+if (!def->is_CFG()) {
+for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
+Node *use = def->fast_out(j);
+if (has_node(use) && use->in(0) != C->top() &&
+(!peel.test(use->_idx) ||
+(use->is_Phi() && use->in(0) == head)) ) {
+worklist.push(use);
+}
+}
+while( worklist.size() ) {
+Node *use = worklist.pop();
+for (uint j = 1; j < use->req(); j++) {
+Node* n = use->in(j);
+if (n == def) {
+// "def" is in peel set, "use" is not in peel set
+// or "use" is in the entry boundary (a phi) of the peel set
+Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
+if ( loop->is_member(get_loop( use_c )) ) {
+// use is in loop
+if (old_new[use->_idx] != NULL) { // null for dead code
+Node* use_clone = old_new[use->_idx];
+_igvn.hash_delete(use);
+use->set_req(j, C->top());
+_igvn._worklist.push(use);
+insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
+}
+} else {
+assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
+// use is not in the loop, check if the live range includes the cut
+Node* lp_if = use_c->in(orig_exit_idx)->in(0);
+if (not_peel.test(lp_if->_idx)) {
+assert(j == orig_exit_idx, "use from original loop");
+insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
+}
+}
+}
+}
+}
+}
+}
+// Step 3b: retarget control
+// Redirect control to the new loop head if a cloned node in
+// the not_peeled region has control that points into the peeled region.
+// This necessary because the cloned peeled region will be outside
+// the loop.
+//                            from    to
+//          cloned-peeled    <---+
+//    new_head_clone:            |    <--+
+//          cloned-not_peeled  in(0)    in(0)
+//          orig-peeled
+for(i = 0; i < loop->_body.size(); i++ ) {
+Node *n = loop->_body.at(i);
+if (!n->is_CFG()           && n->in(0) != NULL        &&
+not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
+Node* n_clone = old_new[n->_idx];
+_igvn.hash_delete(n_clone);
+n_clone->set_req(0, new_head_clone);
+_igvn._worklist.push(n_clone);
+}
+}
+// Backedge of the surviving new_head (the clone) is original last_peel
+_igvn.hash_delete(new_head_clone);
+new_head_clone->set_req(LoopNode::LoopBackControl, last_peel);
+_igvn._worklist.push(new_head_clone);
+// Cut first node in original not_peel set
+_igvn.hash_delete(new_head);
+new_head->set_req(LoopNode::EntryControl, C->top());
+new_head->set_req(LoopNode::LoopBackControl, C->top());
+_igvn._worklist.push(new_head);
+// Copy head_clone back-branch info to original head
+// and remove original head's loop entry and
+// clone head's back-branch
+_igvn.hash_delete(head);
+_igvn.hash_delete(head_clone);
+head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
+head->set_req(LoopNode::LoopBackControl, C->top());
+head_clone->set_req(LoopNode::LoopBackControl, C->top());
+_igvn._worklist.push(head);
+_igvn._worklist.push(head_clone);
+// Similarly modify the phis
+for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
+Node* use = head->fast_out(k);
+if (use->is_Phi() && use->outcnt() > 0) {
+Node* use_clone = old_new[use->_idx];
+_igvn.hash_delete(use);
+_igvn.hash_delete(use_clone);
+use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
+use->set_req(LoopNode::LoopBackControl, C->top());
+use_clone->set_req(LoopNode::LoopBackControl, C->top());
+_igvn._worklist.push(use);
+_igvn._worklist.push(use_clone);
+}
+}
+// Step 4: update dominator tree and dominator depth
+set_idom(head, orig_tail_clone, dd);
+recompute_dom_depth();
+// Inhibit more partial peeling on this loop
+new_head_clone->set_partial_peel_loop();
+C->set_major_progress();
+#if !defined(PRODUCT)
+if (TracePartialPeeling) {
+tty->print_cr("\nafter partial peel one iteration");
+Node_List wl(area);
+Node* t = last_peel;
+while (true) {
+wl.push(t);
+if (t == head_clone) break;
+t = idom(t);
+}
+while (wl.size() > 0) {
+Node* tt = wl.pop();
+if (tt == head) tty->print_cr("orig head");
+else if (tt == new_head_clone) tty->print_cr("new head");
+else if (tt == head_clone) tty->print_cr("clone head");
+tt->dump();
+}
+}
+#endif
+return true;
+}
+//------------------------------reorg_offsets----------------------------------
+// Reorganize offset computations to lower register pressure.  Mostly
+// prevent loop-fallout uses of the pre-incremented trip counter (which are
+// then alive with the post-incremented trip counter forcing an extra
+// register move)
+void PhaseIdealLoop::reorg_offsets( IdealLoopTree *loop ) {
+CountedLoopNode *cl = loop->_head->as_CountedLoop();
+CountedLoopEndNode *cle = cl->loopexit();
+if( !cle ) return;            // The occasional dead loop
+// Find loop exit control
+Node *exit = cle->proj_out(false);
+assert( exit->Opcode() == Op_IfFalse, "" );
+// Check for the special case of folks using the pre-incremented
+// trip-counter on the fall-out path (forces the pre-incremented
+// and post-incremented trip counter to be live at the same time).
+// Fix this by adjusting to use the post-increment trip counter.
+Node *phi = cl->phi();
+if( !phi ) return;            // Dead infinite loop
+bool progress = true;
+while (progress) {
+progress = false;
+for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
+Node* use = phi->fast_out(i);   // User of trip-counter
+if (!has_ctrl(use))  continue;
+Node *u_ctrl = get_ctrl(use);
+if( use->is_Phi() ) {
+u_ctrl = NULL;
+for( uint j = 1; j < use->req(); j++ )
+if( use->in(j) == phi )
+u_ctrl = dom_lca( u_ctrl, use->in(0)->in(j) );
+}
+IdealLoopTree *u_loop = get_loop(u_ctrl);
+// Look for loop-invariant use
+if( u_loop == loop ) continue;
+if( loop->is_member( u_loop ) ) continue;
+// Check that use is live out the bottom.  Assuming the trip-counter
+// update is right at the bottom, uses of of the loop middle are ok.
+if( dom_lca( exit, u_ctrl ) != exit ) continue;
+// protect against stride not being a constant
+if( !cle->stride_is_con() ) continue;
+// Hit!  Refactor use to use the post-incremented tripcounter.
+// Compute a post-increment tripcounter.
+Node *opaq = new (C, 2) Opaque2Node( cle->incr() );
+register_new_node( opaq, u_ctrl );
+Node *neg_stride = _igvn.intcon(-cle->stride_con());
+set_ctrl(neg_stride, C->root());
+Node *post = new (C, 3) AddINode( opaq, neg_stride);
+register_new_node( post, u_ctrl );
+_igvn.hash_delete(use);
+_igvn._worklist.push(use);
+for( uint j = 1; j < use->req(); j++ )
+if( use->in(j) == phi )
+use->set_req(j, post);
+// Since DU info changed, rerun loop
+progress = true;
+break;
+}
+}
+}

Mercurial > hg > truffle

comparison src/share/vm/opto/loopopts.cpp @ 0:a61af66fc99e jdk7-b24