Wed, 02 Jul 2008 12:55:16 -0700
6719955: Update copyright year
Summary: Update copyright year for files that have been modified in 2008
Reviewed-by: ohair, tbell
1 /*
2 * Copyright 1999-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_loopopts.cpp.incl"
28 //=============================================================================
29 //------------------------------split_thru_phi---------------------------------
30 // Split Node 'n' through merge point if there is enough win.
31 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
32 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
33 // ConvI2L may have type information on it which is unsafe to push up
34 // so disable this for now
35 return NULL;
36 }
37 int wins = 0;
38 assert( !n->is_CFG(), "" );
39 assert( region->is_Region(), "" );
41 const Type* type = n->bottom_type();
42 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
43 Node *phi;
44 if( t_oop != NULL && t_oop->is_instance_field() ) {
45 int iid = t_oop->instance_id();
46 int index = C->get_alias_index(t_oop);
47 int offset = t_oop->offset();
48 phi = new (C,region->req()) PhiNode(region, type, NULL, iid, index, offset);
49 } else {
50 phi = new (C,region->req()) PhiNode(region, type);
51 }
52 uint old_unique = C->unique();
53 for( uint i = 1; i < region->req(); i++ ) {
54 Node *x;
55 Node* the_clone = NULL;
56 if( region->in(i) == C->top() ) {
57 x = C->top(); // Dead path? Use a dead data op
58 } else {
59 x = n->clone(); // Else clone up the data op
60 the_clone = x; // Remember for possible deletion.
61 // Alter data node to use pre-phi inputs
62 if( n->in(0) == region )
63 x->set_req( 0, region->in(i) );
64 for( uint j = 1; j < n->req(); j++ ) {
65 Node *in = n->in(j);
66 if( in->is_Phi() && in->in(0) == region )
67 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
68 }
69 }
70 // Check for a 'win' on some paths
71 const Type *t = x->Value(&_igvn);
73 bool singleton = t->singleton();
75 // A TOP singleton indicates that there are no possible values incoming
76 // along a particular edge. In most cases, this is OK, and the Phi will
77 // be eliminated later in an Ideal call. However, we can't allow this to
78 // happen if the singleton occurs on loop entry, as the elimination of
79 // the PhiNode may cause the resulting node to migrate back to a previous
80 // loop iteration.
81 if( singleton && t == Type::TOP ) {
82 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
83 // irreducible loop may not be indicated by an affirmative is_Loop());
84 // therefore, the only top we can split thru a phi is on a backedge of
85 // a loop.
86 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
87 }
89 if( singleton ) {
90 wins++;
91 x = ((PhaseGVN&)_igvn).makecon(t);
92 } else {
93 // We now call Identity to try to simplify the cloned node.
94 // Note that some Identity methods call phase->type(this).
95 // Make sure that the type array is big enough for
96 // our new node, even though we may throw the node away.
97 // (Note: This tweaking with igvn only works because x is a new node.)
98 _igvn.set_type(x, t);
99 Node *y = x->Identity(&_igvn);
100 if( y != x ) {
101 wins++;
102 x = y;
103 } else {
104 y = _igvn.hash_find(x);
105 if( y ) {
106 wins++;
107 x = y;
108 } else {
109 // Else x is a new node we are keeping
110 // We do not need register_new_node_with_optimizer
111 // because set_type has already been called.
112 _igvn._worklist.push(x);
113 }
114 }
115 }
116 if (x != the_clone && the_clone != NULL)
117 _igvn.remove_dead_node(the_clone);
118 phi->set_req( i, x );
119 }
120 // Too few wins?
121 if( wins <= policy ) {
122 _igvn.remove_dead_node(phi);
123 return NULL;
124 }
126 // Record Phi
127 register_new_node( phi, region );
129 for( uint i2 = 1; i2 < phi->req(); i2++ ) {
130 Node *x = phi->in(i2);
131 // If we commoned up the cloned 'x' with another existing Node,
132 // the existing Node picks up a new use. We need to make the
133 // existing Node occur higher up so it dominates its uses.
134 Node *old_ctrl;
135 IdealLoopTree *old_loop;
137 // The occasional new node
138 if( x->_idx >= old_unique ) { // Found a new, unplaced node?
139 old_ctrl = x->is_Con() ? C->root() : NULL;
140 old_loop = NULL; // Not in any prior loop
141 } else {
142 old_ctrl = x->is_Con() ? C->root() : get_ctrl(x);
143 old_loop = get_loop(old_ctrl); // Get prior loop
144 }
145 // New late point must dominate new use
146 Node *new_ctrl = dom_lca( old_ctrl, region->in(i2) );
147 // Set new location
148 set_ctrl(x, new_ctrl);
149 IdealLoopTree *new_loop = get_loop( new_ctrl );
150 // If changing loop bodies, see if we need to collect into new body
151 if( old_loop != new_loop ) {
152 if( old_loop && !old_loop->_child )
153 old_loop->_body.yank(x);
154 if( !new_loop->_child )
155 new_loop->_body.push(x); // Collect body info
156 }
157 }
159 return phi;
160 }
162 //------------------------------dominated_by------------------------------------
163 // Replace the dominated test with an obvious true or false. Place it on the
164 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
165 // live path up to the dominating control.
166 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff ) {
167 #ifndef PRODUCT
168 if( VerifyLoopOptimizations && PrintOpto ) tty->print_cr("dominating test");
169 #endif
172 // prevdom is the dominating projection of the dominating test.
173 assert( iff->is_If(), "" );
174 assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
175 int pop = prevdom->Opcode();
176 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
177 // 'con' is set to true or false to kill the dominated test.
178 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
179 set_ctrl(con, C->root()); // Constant gets a new use
180 // Hack the dominated test
181 _igvn.hash_delete(iff);
182 iff->set_req(1, con);
183 _igvn._worklist.push(iff);
185 // If I dont have a reachable TRUE and FALSE path following the IfNode then
186 // I can assume this path reaches an infinite loop. In this case it's not
187 // important to optimize the data Nodes - either the whole compilation will
188 // be tossed or this path (and all data Nodes) will go dead.
189 if( iff->outcnt() != 2 ) return;
191 // Make control-dependent data Nodes on the live path (path that will remain
192 // once the dominated IF is removed) become control-dependent on the
193 // dominating projection.
194 Node* dp = ((IfNode*)iff)->proj_out(pop == Op_IfTrue);
195 IdealLoopTree *old_loop = get_loop(dp);
197 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
198 Node* cd = dp->fast_out(i); // Control-dependent node
199 if( cd->depends_only_on_test() ) {
200 assert( cd->in(0) == dp, "" );
201 _igvn.hash_delete( cd );
202 cd->set_req(0, prevdom);
203 set_early_ctrl( cd );
204 _igvn._worklist.push(cd);
205 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
206 if( old_loop != new_loop ) {
207 if( !old_loop->_child ) old_loop->_body.yank(cd);
208 if( !new_loop->_child ) new_loop->_body.push(cd);
209 }
210 --i;
211 --imax;
212 }
213 }
214 }
216 //------------------------------has_local_phi_input----------------------------
217 // Return TRUE if 'n' has Phi inputs from its local block and no other
218 // block-local inputs (all non-local-phi inputs come from earlier blocks)
219 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
220 Node *n_ctrl = get_ctrl(n);
221 // See if some inputs come from a Phi in this block, or from before
222 // this block.
223 uint i;
224 for( i = 1; i < n->req(); i++ ) {
225 Node *phi = n->in(i);
226 if( phi->is_Phi() && phi->in(0) == n_ctrl )
227 break;
228 }
229 if( i >= n->req() )
230 return NULL; // No Phi inputs; nowhere to clone thru
232 // Check for inputs created between 'n' and the Phi input. These
233 // must split as well; they have already been given the chance
234 // (courtesy of a post-order visit) and since they did not we must
235 // recover the 'cost' of splitting them by being very profitable
236 // when splitting 'n'. Since this is unlikely we simply give up.
237 for( i = 1; i < n->req(); i++ ) {
238 Node *m = n->in(i);
239 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
240 // We allow the special case of AddP's with no local inputs.
241 // This allows us to split-up address expressions.
242 if (m->is_AddP() &&
243 get_ctrl(m->in(2)) != n_ctrl &&
244 get_ctrl(m->in(3)) != n_ctrl) {
245 // Move the AddP up to dominating point
246 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
247 continue;
248 }
249 return NULL;
250 }
251 }
253 return n_ctrl;
254 }
256 //------------------------------remix_address_expressions----------------------
257 // Rework addressing expressions to get the most loop-invariant stuff
258 // moved out. We'd like to do all associative operators, but it's especially
259 // important (common) to do address expressions.
260 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
261 if (!has_ctrl(n)) return NULL;
262 Node *n_ctrl = get_ctrl(n);
263 IdealLoopTree *n_loop = get_loop(n_ctrl);
265 // See if 'n' mixes loop-varying and loop-invariant inputs and
266 // itself is loop-varying.
268 // Only interested in binary ops (and AddP)
269 if( n->req() < 3 || n->req() > 4 ) return NULL;
271 Node *n1_ctrl = get_ctrl(n->in( 1));
272 Node *n2_ctrl = get_ctrl(n->in( 2));
273 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
274 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
275 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
276 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
278 // Does one of my inputs spin in a tighter loop than self?
279 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
280 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
281 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
282 return NULL; // Leave well enough alone
284 // Is at least one of my inputs loop-invariant?
285 if( n1_loop == n_loop &&
286 n2_loop == n_loop &&
287 n3_loop == n_loop )
288 return NULL; // No loop-invariant inputs
291 int n_op = n->Opcode();
293 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
294 if( n_op == Op_LShiftI ) {
295 // Scale is loop invariant
296 Node *scale = n->in(2);
297 Node *scale_ctrl = get_ctrl(scale);
298 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
299 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
300 return NULL;
301 const TypeInt *scale_t = scale->bottom_type()->isa_int();
302 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
303 return NULL; // Dont bother with byte/short masking
304 // Add must vary with loop (else shift would be loop-invariant)
305 Node *add = n->in(1);
306 Node *add_ctrl = get_ctrl(add);
307 IdealLoopTree *add_loop = get_loop(add_ctrl);
308 //assert( n_loop == add_loop, "" );
309 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
311 // Convert I-V into I+ (0-V); same for V-I
312 if( add->Opcode() == Op_SubI &&
313 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
314 Node *zero = _igvn.intcon(0);
315 set_ctrl(zero, C->root());
316 Node *neg = new (C, 3) SubINode( _igvn.intcon(0), add->in(2) );
317 register_new_node( neg, get_ctrl(add->in(2) ) );
318 add = new (C, 3) AddINode( add->in(1), neg );
319 register_new_node( add, add_ctrl );
320 }
321 if( add->Opcode() != Op_AddI ) return NULL;
322 // See if one add input is loop invariant
323 Node *add_var = add->in(1);
324 Node *add_var_ctrl = get_ctrl(add_var);
325 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
326 Node *add_invar = add->in(2);
327 Node *add_invar_ctrl = get_ctrl(add_invar);
328 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
329 if( add_var_loop == n_loop ) {
330 } else if( add_invar_loop == n_loop ) {
331 // Swap to find the invariant part
332 add_invar = add_var;
333 add_invar_ctrl = add_var_ctrl;
334 add_invar_loop = add_var_loop;
335 add_var = add->in(2);
336 Node *add_var_ctrl = get_ctrl(add_var);
337 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
338 } else // Else neither input is loop invariant
339 return NULL;
340 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
341 return NULL; // No invariant part of the add?
343 // Yes! Reshape address expression!
344 Node *inv_scale = new (C, 3) LShiftINode( add_invar, scale );
345 register_new_node( inv_scale, add_invar_ctrl );
346 Node *var_scale = new (C, 3) LShiftINode( add_var, scale );
347 register_new_node( var_scale, n_ctrl );
348 Node *var_add = new (C, 3) AddINode( var_scale, inv_scale );
349 register_new_node( var_add, n_ctrl );
350 _igvn.hash_delete( n );
351 _igvn.subsume_node( n, var_add );
352 return var_add;
353 }
355 // Replace (I+V) with (V+I)
356 if( n_op == Op_AddI ||
357 n_op == Op_AddL ||
358 n_op == Op_AddF ||
359 n_op == Op_AddD ||
360 n_op == Op_MulI ||
361 n_op == Op_MulL ||
362 n_op == Op_MulF ||
363 n_op == Op_MulD ) {
364 if( n2_loop == n_loop ) {
365 assert( n1_loop != n_loop, "" );
366 n->swap_edges(1, 2);
367 }
368 }
370 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
371 // but not if I2 is a constant.
372 if( n_op == Op_AddP ) {
373 if( n2_loop == n_loop && n3_loop != n_loop ) {
374 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
375 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
376 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
377 IdealLoopTree *n22loop = get_loop( n22_ctrl );
378 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
379 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
380 n23_loop == n_loop ) {
381 Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
382 // Stuff new AddP in the loop preheader
383 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
384 Node *add2 = new (C, 4) AddPNode( n->in(1), add1, n->in(2)->in(3) );
385 register_new_node( add2, n_ctrl );
386 _igvn.hash_delete( n );
387 _igvn.subsume_node( n, add2 );
388 return add2;
389 }
390 }
391 }
393 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
394 if( n2_loop != n_loop && n3_loop == n_loop ) {
395 if( n->in(3)->Opcode() == Op_AddI ) {
396 Node *V = n->in(3)->in(1);
397 Node *I = n->in(3)->in(2);
398 if( is_member(n_loop,get_ctrl(V)) ) {
399 } else {
400 Node *tmp = V; V = I; I = tmp;
401 }
402 if( !is_member(n_loop,get_ctrl(I)) ) {
403 Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2), I );
404 // Stuff new AddP in the loop preheader
405 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
406 Node *add2 = new (C, 4) AddPNode( n->in(1), add1, V );
407 register_new_node( add2, n_ctrl );
408 _igvn.hash_delete( n );
409 _igvn.subsume_node( n, add2 );
410 return add2;
411 }
412 }
413 }
414 }
416 return NULL;
417 }
419 //------------------------------conditional_move-------------------------------
420 // Attempt to replace a Phi with a conditional move. We have some pretty
421 // strict profitability requirements. All Phis at the merge point must
422 // be converted, so we can remove the control flow. We need to limit the
423 // number of c-moves to a small handful. All code that was in the side-arms
424 // of the CFG diamond is now speculatively executed. This code has to be
425 // "cheap enough". We are pretty much limited to CFG diamonds that merge
426 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
427 Node *PhaseIdealLoop::conditional_move( Node *region ) {
429 assert( region->is_Region(), "sanity check" );
430 if( region->req() != 3 ) return NULL;
432 // Check for CFG diamond
433 Node *lp = region->in(1);
434 Node *rp = region->in(2);
435 if( !lp || !rp ) return NULL;
436 Node *lp_c = lp->in(0);
437 if( lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If() ) return NULL;
438 IfNode *iff = lp_c->as_If();
440 // Check for highly predictable branch. No point in CMOV'ing if
441 // we are going to predict accurately all the time.
442 // %%% This hides patterns produced by utility methods like Math.min.
443 if( iff->_prob < PROB_UNLIKELY_MAG(3) ||
444 iff->_prob > PROB_LIKELY_MAG(3) )
445 return NULL;
447 // Check for ops pinned in an arm of the diamond.
448 // Can't remove the control flow in this case
449 if( lp->outcnt() > 1 ) return NULL;
450 if( rp->outcnt() > 1 ) return NULL;
452 // Check profitability
453 int cost = 0;
454 int phis = 0;
455 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
456 Node *out = region->fast_out(i);
457 if( !out->is_Phi() ) continue; // Ignore other control edges, etc
458 phis++;
459 PhiNode* phi = out->as_Phi();
460 switch (phi->type()->basic_type()) {
461 case T_LONG:
462 cost++; // Probably encodes as 2 CMOV's
463 case T_INT: // These all CMOV fine
464 case T_FLOAT:
465 case T_DOUBLE:
466 case T_ADDRESS: // (RawPtr)
467 case T_NARROWOOP:
468 cost++;
469 break;
470 case T_OBJECT: { // Base oops are OK, but not derived oops
471 const TypeOopPtr *tp = phi->type()->isa_oopptr();
472 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
473 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
474 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
475 // have a Phi for the base here that we convert to a CMOVE all is well
476 // and good. But if the base is dead, we'll not make a CMOVE. Later
477 // the allocator will have to produce a base by creating a CMOVE of the
478 // relevant bases. This puts the allocator in the business of
479 // manufacturing expensive instructions, generally a bad plan.
480 // Just Say No to Conditionally-Moved Derived Pointers.
481 if( tp && tp->offset() != 0 )
482 return NULL;
483 cost++;
484 break;
485 }
486 default:
487 return NULL; // In particular, can't do memory or I/O
488 }
489 // Add in cost any speculative ops
490 for( uint j = 1; j < region->req(); j++ ) {
491 Node *proj = region->in(j);
492 Node *inp = phi->in(j);
493 if (get_ctrl(inp) == proj) { // Found local op
494 cost++;
495 // Check for a chain of dependent ops; these will all become
496 // speculative in a CMOV.
497 for( uint k = 1; k < inp->req(); k++ )
498 if (get_ctrl(inp->in(k)) == proj)
499 return NULL; // Too much speculative goo
500 }
501 }
502 // See if the Phi is used by a Cmp. This will likely Split-If, a
503 // higher-payoff operation.
504 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
505 Node* use = phi->fast_out(k);
506 if( use->is_Cmp() )
507 return NULL;
508 }
509 }
510 if( cost >= ConditionalMoveLimit ) return NULL; // Too much goo
511 Node* bol = iff->in(1);
512 assert( bol->Opcode() == Op_Bool, "" );
513 int cmp_op = bol->in(1)->Opcode();
514 // It is expensive to generate flags from a float compare.
515 // Avoid duplicated float compare.
516 if( phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
518 // --------------
519 // Now replace all Phis with CMOV's
520 Node *cmov_ctrl = iff->in(0);
521 uint flip = (lp->Opcode() == Op_IfTrue);
522 while( 1 ) {
523 PhiNode* phi = NULL;
524 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
525 Node *out = region->fast_out(i);
526 if (out->is_Phi()) {
527 phi = out->as_Phi();
528 break;
529 }
530 }
531 if (phi == NULL) break;
532 #ifndef PRODUCT
533 if( PrintOpto && VerifyLoopOptimizations ) tty->print_cr("CMOV");
534 #endif
535 // Move speculative ops
536 for( uint j = 1; j < region->req(); j++ ) {
537 Node *proj = region->in(j);
538 Node *inp = phi->in(j);
539 if (get_ctrl(inp) == proj) { // Found local op
540 #ifndef PRODUCT
541 if( PrintOpto && VerifyLoopOptimizations ) {
542 tty->print(" speculate: ");
543 inp->dump();
544 }
545 #endif
546 set_ctrl(inp, cmov_ctrl);
547 }
548 }
549 Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) );
550 register_new_node( cmov, cmov_ctrl );
551 _igvn.hash_delete(phi);
552 _igvn.subsume_node( phi, cmov );
553 #ifndef PRODUCT
554 if( VerifyLoopOptimizations ) verify();
555 #endif
556 }
558 // The useless CFG diamond will fold up later; see the optimization in
559 // RegionNode::Ideal.
560 _igvn._worklist.push(region);
562 return iff->in(1);
563 }
565 //------------------------------split_if_with_blocks_pre-----------------------
566 // Do the real work in a non-recursive function. Data nodes want to be
567 // cloned in the pre-order so they can feed each other nicely.
568 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
569 // Cloning these guys is unlikely to win
570 int n_op = n->Opcode();
571 if( n_op == Op_MergeMem ) return n;
572 if( n->is_Proj() ) return n;
573 // Do not clone-up CmpFXXX variations, as these are always
574 // followed by a CmpI
575 if( n->is_Cmp() ) return n;
576 // Attempt to use a conditional move instead of a phi/branch
577 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
578 Node *cmov = conditional_move( n );
579 if( cmov ) return cmov;
580 }
581 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;
582 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
583 n_op == Op_Opaque2 ) {
584 if( !C->major_progress() ) // If chance of no more loop opts...
585 _igvn._worklist.push(n); // maybe we'll remove them
586 return n;
587 }
589 if( n->is_Con() ) return n; // No cloning for Con nodes
591 Node *n_ctrl = get_ctrl(n);
592 if( !n_ctrl ) return n; // Dead node
594 // Attempt to remix address expressions for loop invariants
595 Node *m = remix_address_expressions( n );
596 if( m ) return m;
598 // Determine if the Node has inputs from some local Phi.
599 // Returns the block to clone thru.
600 Node *n_blk = has_local_phi_input( n );
601 if( !n_blk ) return n;
602 // Do not clone the trip counter through on a CountedLoop
603 // (messes up the canonical shape).
604 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
606 // Check for having no control input; not pinned. Allow
607 // dominating control.
608 if( n->in(0) ) {
609 Node *dom = idom(n_blk);
610 if( dom_lca( n->in(0), dom ) != n->in(0) )
611 return n;
612 }
613 // Policy: when is it profitable. You must get more wins than
614 // policy before it is considered profitable. Policy is usually 0,
615 // so 1 win is considered profitable. Big merges will require big
616 // cloning, so get a larger policy.
617 int policy = n_blk->req() >> 2;
619 // If the loop is a candidate for range check elimination,
620 // delay splitting through it's phi until a later loop optimization
621 if (n_blk->is_CountedLoop()) {
622 IdealLoopTree *lp = get_loop(n_blk);
623 if (lp && lp->_rce_candidate) {
624 return n;
625 }
626 }
628 // Use same limit as split_if_with_blocks_post
629 if( C->unique() > 35000 ) return n; // Method too big
631 // Split 'n' through the merge point if it is profitable
632 Node *phi = split_thru_phi( n, n_blk, policy );
633 if( !phi ) return n;
635 // Found a Phi to split thru!
636 // Replace 'n' with the new phi
637 _igvn.hash_delete(n);
638 _igvn.subsume_node( n, phi );
639 // Moved a load around the loop, 'en-registering' something.
640 if( n_blk->Opcode() == Op_Loop && n->is_Load() &&
641 !phi->in(LoopNode::LoopBackControl)->is_Load() )
642 C->set_major_progress();
644 return phi;
645 }
647 static bool merge_point_too_heavy(Compile* C, Node* region) {
648 // Bail out if the region and its phis have too many users.
649 int weight = 0;
650 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
651 weight += region->fast_out(i)->outcnt();
652 }
653 int nodes_left = MaxNodeLimit - C->unique();
654 if (weight * 8 > nodes_left) {
655 #ifndef PRODUCT
656 if (PrintOpto)
657 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
658 #endif
659 return true;
660 } else {
661 return false;
662 }
663 }
665 #ifdef _LP64
666 static bool merge_point_safe(Node* region) {
667 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
668 // having a PhiNode input. This sidesteps the dangerous case where the split
669 // ConvI2LNode may become TOP if the input Value() does not
670 // overlap the ConvI2L range, leaving a node which may not dominate its
671 // uses.
672 // A better fix for this problem can be found in the BugTraq entry, but
673 // expediency for Mantis demands this hack.
674 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
675 Node* n = region->fast_out(i);
676 if (n->is_Phi()) {
677 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
678 Node* m = n->fast_out(j);
679 if (m->Opcode() == Op_ConvI2L) {
680 return false;
681 }
682 }
683 }
684 }
685 return true;
686 }
687 #endif
690 //------------------------------place_near_use---------------------------------
691 // Place some computation next to use but not inside inner loops.
692 // For inner loop uses move it to the preheader area.
693 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
694 IdealLoopTree *u_loop = get_loop( useblock );
695 return (u_loop->_irreducible || u_loop->_child)
696 ? useblock
697 : u_loop->_head->in(LoopNode::EntryControl);
698 }
701 //------------------------------split_if_with_blocks_post----------------------
702 // Do the real work in a non-recursive function. CFG hackery wants to be
703 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
704 // info.
705 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
707 // Cloning Cmp through Phi's involves the split-if transform.
708 // FastLock is not used by an If
709 if( n->is_Cmp() && !n->is_FastLock() ) {
710 if( C->unique() > 35000 ) return; // Method too big
712 // Do not do 'split-if' if irreducible loops are present.
713 if( _has_irreducible_loops )
714 return;
716 Node *n_ctrl = get_ctrl(n);
717 // Determine if the Node has inputs from some local Phi.
718 // Returns the block to clone thru.
719 Node *n_blk = has_local_phi_input( n );
720 if( n_blk != n_ctrl ) return;
722 if( merge_point_too_heavy(C, n_ctrl) )
723 return;
725 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
726 Node *bol = n->unique_out();
727 assert( bol->is_Bool(), "expect a bool here" );
728 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
729 Node *iff = bol->unique_out();
731 // Check some safety conditions
732 if( iff->is_If() ) { // Classic split-if?
733 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
734 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
735 if( get_ctrl(iff->in(2)) == n_ctrl ||
736 get_ctrl(iff->in(3)) == n_ctrl )
737 return; // Inputs not yet split-up
738 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
739 return; // Loop-invar test gates loop-varying CMOVE
740 }
741 } else {
742 return; // some other kind of node, such as an Allocate
743 }
745 // Do not do 'split-if' if some paths are dead. First do dead code
746 // elimination and then see if its still profitable.
747 for( uint i = 1; i < n_ctrl->req(); i++ )
748 if( n_ctrl->in(i) == C->top() )
749 return;
751 // When is split-if profitable? Every 'win' on means some control flow
752 // goes dead, so it's almost always a win.
753 int policy = 0;
754 // If trying to do a 'Split-If' at the loop head, it is only
755 // profitable if the cmp folds up on BOTH paths. Otherwise we
756 // risk peeling a loop forever.
758 // CNC - Disabled for now. Requires careful handling of loop
759 // body selection for the cloned code. Also, make sure we check
760 // for any input path not being in the same loop as n_ctrl. For
761 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
762 // because the alternative loop entry points won't be converted
763 // into LoopNodes.
764 IdealLoopTree *n_loop = get_loop(n_ctrl);
765 for( uint j = 1; j < n_ctrl->req(); j++ )
766 if( get_loop(n_ctrl->in(j)) != n_loop )
767 return;
769 #ifdef _LP64
770 // Check for safety of the merge point.
771 if( !merge_point_safe(n_ctrl) ) {
772 return;
773 }
774 #endif
776 // Split compare 'n' through the merge point if it is profitable
777 Node *phi = split_thru_phi( n, n_ctrl, policy );
778 if( !phi ) return;
780 // Found a Phi to split thru!
781 // Replace 'n' with the new phi
782 _igvn.hash_delete(n);
783 _igvn.subsume_node( n, phi );
785 // Now split the bool up thru the phi
786 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
787 _igvn.hash_delete(bol);
788 _igvn.subsume_node( bol, bolphi );
789 assert( iff->in(1) == bolphi, "" );
790 if( bolphi->Value(&_igvn)->singleton() )
791 return;
793 // Conditional-move? Must split up now
794 if( !iff->is_If() ) {
795 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
796 _igvn.hash_delete(iff);
797 _igvn.subsume_node( iff, cmovphi );
798 return;
799 }
801 // Now split the IF
802 do_split_if( iff );
803 return;
804 }
806 // Check for an IF ready to split; one that has its
807 // condition codes input coming from a Phi at the block start.
808 int n_op = n->Opcode();
810 // Check for an IF being dominated by another IF same test
811 if( n_op == Op_If ) {
812 Node *bol = n->in(1);
813 uint max = bol->outcnt();
814 // Check for same test used more than once?
815 if( n_op == Op_If && max > 1 && bol->is_Bool() ) {
816 // Search up IDOMs to see if this IF is dominated.
817 Node *cutoff = get_ctrl(bol);
819 // Now search up IDOMs till cutoff, looking for a dominating test
820 Node *prevdom = n;
821 Node *dom = idom(prevdom);
822 while( dom != cutoff ) {
823 if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) {
824 // Replace the dominated test with an obvious true or false.
825 // Place it on the IGVN worklist for later cleanup.
826 C->set_major_progress();
827 dominated_by( prevdom, n );
828 #ifndef PRODUCT
829 if( VerifyLoopOptimizations ) verify();
830 #endif
831 return;
832 }
833 prevdom = dom;
834 dom = idom(prevdom);
835 }
836 }
837 }
839 // See if a shared loop-varying computation has no loop-varying uses.
840 // Happens if something is only used for JVM state in uncommon trap exits,
841 // like various versions of induction variable+offset. Clone the
842 // computation per usage to allow it to sink out of the loop.
843 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
844 Node *n_ctrl = get_ctrl(n);
845 IdealLoopTree *n_loop = get_loop(n_ctrl);
846 if( n_loop != _ltree_root ) {
847 DUIterator_Fast imax, i = n->fast_outs(imax);
848 for (; i < imax; i++) {
849 Node* u = n->fast_out(i);
850 if( !has_ctrl(u) ) break; // Found control user
851 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
852 if( u_loop == n_loop ) break; // Found loop-varying use
853 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
854 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
855 }
856 bool did_break = (i < imax); // Did we break out of the previous loop?
857 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
858 Node *late_load_ctrl;
859 if (n->is_Load()) {
860 // If n is a load, get and save the result from get_late_ctrl(),
861 // to be later used in calculating the control for n's clones.
862 clear_dom_lca_tags();
863 late_load_ctrl = get_late_ctrl(n, n_ctrl);
864 }
865 // If n is a load, and the late control is the same as the current
866 // control, then the cloning of n is a pointless exercise, because
867 // GVN will ensure that we end up where we started.
868 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
869 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
870 Node *u = n->last_out(j); // Clone private computation per use
871 _igvn.hash_delete(u);
872 _igvn._worklist.push(u);
873 Node *x = n->clone(); // Clone computation
874 Node *x_ctrl = NULL;
875 if( u->is_Phi() ) {
876 // Replace all uses of normal nodes. Replace Phi uses
877 // individually, so the seperate Nodes can sink down
878 // different paths.
879 uint k = 1;
880 while( u->in(k) != n ) k++;
881 u->set_req( k, x );
882 // x goes next to Phi input path
883 x_ctrl = u->in(0)->in(k);
884 --j;
885 } else { // Normal use
886 // Replace all uses
887 for( uint k = 0; k < u->req(); k++ ) {
888 if( u->in(k) == n ) {
889 u->set_req( k, x );
890 --j;
891 }
892 }
893 x_ctrl = get_ctrl(u);
894 }
896 // Find control for 'x' next to use but not inside inner loops.
897 // For inner loop uses get the preheader area.
898 x_ctrl = place_near_use(x_ctrl);
900 if (n->is_Load()) {
901 // For loads, add a control edge to a CFG node outside of the loop
902 // to force them to not combine and return back inside the loop
903 // during GVN optimization (4641526).
904 //
905 // Because we are setting the actual control input, factor in
906 // the result from get_late_ctrl() so we respect any
907 // anti-dependences. (6233005).
908 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
910 // Don't allow the control input to be a CFG splitting node.
911 // Such nodes should only have ProjNodes as outs, e.g. IfNode
912 // should only have IfTrueNode and IfFalseNode (4985384).
913 x_ctrl = find_non_split_ctrl(x_ctrl);
914 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
916 x->set_req(0, x_ctrl);
917 }
918 register_new_node(x, x_ctrl);
920 // Some institutional knowledge is needed here: 'x' is
921 // yanked because if the optimizer runs GVN on it all the
922 // cloned x's will common up and undo this optimization and
923 // be forced back in the loop. This is annoying because it
924 // makes +VerifyOpto report false-positives on progress. I
925 // tried setting control edges on the x's to force them to
926 // not combine, but the matching gets worried when it tries
927 // to fold a StoreP and an AddP together (as part of an
928 // address expression) and the AddP and StoreP have
929 // different controls.
930 if( !x->is_Load() ) _igvn._worklist.yank(x);
931 }
932 _igvn.remove_dead_node(n);
933 }
934 }
935 }
936 }
938 // Check for Opaque2's who's loop has disappeared - who's input is in the
939 // same loop nest as their output. Remove 'em, they are no longer useful.
940 if( n_op == Op_Opaque2 &&
941 n->in(1) != NULL &&
942 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
943 _igvn.add_users_to_worklist(n);
944 _igvn.hash_delete(n);
945 _igvn.subsume_node( n, n->in(1) );
946 }
947 }
949 //------------------------------split_if_with_blocks---------------------------
950 // Check for aggressive application of 'split-if' optimization,
951 // using basic block level info.
952 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
953 Node *n = C->root();
954 visited.set(n->_idx); // first, mark node as visited
955 // Do pre-visit work for root
956 n = split_if_with_blocks_pre( n );
957 uint cnt = n->outcnt();
958 uint i = 0;
959 while (true) {
960 // Visit all children
961 if (i < cnt) {
962 Node* use = n->raw_out(i);
963 ++i;
964 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
965 // Now do pre-visit work for this use
966 use = split_if_with_blocks_pre( use );
967 nstack.push(n, i); // Save parent and next use's index.
968 n = use; // Process all children of current use.
969 cnt = use->outcnt();
970 i = 0;
971 }
972 }
973 else {
974 // All of n's children have been processed, complete post-processing.
975 if (cnt != 0 && !n->is_Con()) {
976 assert(has_node(n), "no dead nodes");
977 split_if_with_blocks_post( n );
978 }
979 if (nstack.is_empty()) {
980 // Finished all nodes on stack.
981 break;
982 }
983 // Get saved parent node and next use's index. Visit the rest of uses.
984 n = nstack.node();
985 cnt = n->outcnt();
986 i = nstack.index();
987 nstack.pop();
988 }
989 }
990 }
993 //=============================================================================
994 //
995 // C L O N E A L O O P B O D Y
996 //
998 //------------------------------clone_iff--------------------------------------
999 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1000 // "Nearly" because all Nodes have been cloned from the original in the loop,
1001 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1002 // through the Phi recursively, and return a Bool.
1003 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1005 // Convert this Phi into a Phi merging Bools
1006 uint i;
1007 for( i = 1; i < phi->req(); i++ ) {
1008 Node *b = phi->in(i);
1009 if( b->is_Phi() ) {
1010 _igvn.hash_delete(phi);
1011 _igvn._worklist.push(phi);
1012 phi->set_req(i, clone_iff( b->as_Phi(), loop ));
1013 } else {
1014 assert( b->is_Bool(), "" );
1015 }
1016 }
1018 Node *sample_bool = phi->in(1);
1019 Node *sample_cmp = sample_bool->in(1);
1021 // Make Phis to merge the Cmp's inputs.
1022 int size = phi->in(0)->req();
1023 PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1024 PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1025 for( i = 1; i < phi->req(); i++ ) {
1026 Node *n1 = phi->in(i)->in(1)->in(1);
1027 Node *n2 = phi->in(i)->in(1)->in(2);
1028 phi1->set_req( i, n1 );
1029 phi2->set_req( i, n2 );
1030 phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
1031 phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
1032 }
1033 // See if these Phis have been made before.
1034 // Register with optimizer
1035 Node *hit1 = _igvn.hash_find_insert(phi1);
1036 if( hit1 ) { // Hit, toss just made Phi
1037 _igvn.remove_dead_node(phi1); // Remove new phi
1038 assert( hit1->is_Phi(), "" );
1039 phi1 = (PhiNode*)hit1; // Use existing phi
1040 } else { // Miss
1041 _igvn.register_new_node_with_optimizer(phi1);
1042 }
1043 Node *hit2 = _igvn.hash_find_insert(phi2);
1044 if( hit2 ) { // Hit, toss just made Phi
1045 _igvn.remove_dead_node(phi2); // Remove new phi
1046 assert( hit2->is_Phi(), "" );
1047 phi2 = (PhiNode*)hit2; // Use existing phi
1048 } else { // Miss
1049 _igvn.register_new_node_with_optimizer(phi2);
1050 }
1051 // Register Phis with loop/block info
1052 set_ctrl(phi1, phi->in(0));
1053 set_ctrl(phi2, phi->in(0));
1054 // Make a new Cmp
1055 Node *cmp = sample_cmp->clone();
1056 cmp->set_req( 1, phi1 );
1057 cmp->set_req( 2, phi2 );
1058 _igvn.register_new_node_with_optimizer(cmp);
1059 set_ctrl(cmp, phi->in(0));
1061 // Make a new Bool
1062 Node *b = sample_bool->clone();
1063 b->set_req(1,cmp);
1064 _igvn.register_new_node_with_optimizer(b);
1065 set_ctrl(b, phi->in(0));
1067 assert( b->is_Bool(), "" );
1068 return (BoolNode*)b;
1069 }
1071 //------------------------------clone_bool-------------------------------------
1072 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1073 // "Nearly" because all Nodes have been cloned from the original in the loop,
1074 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1075 // through the Phi recursively, and return a Bool.
1076 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1077 uint i;
1078 // Convert this Phi into a Phi merging Bools
1079 for( i = 1; i < phi->req(); i++ ) {
1080 Node *b = phi->in(i);
1081 if( b->is_Phi() ) {
1082 _igvn.hash_delete(phi);
1083 _igvn._worklist.push(phi);
1084 phi->set_req(i, clone_bool( b->as_Phi(), loop ));
1085 } else {
1086 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1087 }
1088 }
1090 Node *sample_cmp = phi->in(1);
1092 // Make Phis to merge the Cmp's inputs.
1093 int size = phi->in(0)->req();
1094 PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1095 PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1096 for( uint j = 1; j < phi->req(); j++ ) {
1097 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1098 Node *n1, *n2;
1099 if( cmp_top->is_Cmp() ) {
1100 n1 = cmp_top->in(1);
1101 n2 = cmp_top->in(2);
1102 } else {
1103 n1 = n2 = cmp_top;
1104 }
1105 phi1->set_req( j, n1 );
1106 phi2->set_req( j, n2 );
1107 phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
1108 phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
1109 }
1111 // See if these Phis have been made before.
1112 // Register with optimizer
1113 Node *hit1 = _igvn.hash_find_insert(phi1);
1114 if( hit1 ) { // Hit, toss just made Phi
1115 _igvn.remove_dead_node(phi1); // Remove new phi
1116 assert( hit1->is_Phi(), "" );
1117 phi1 = (PhiNode*)hit1; // Use existing phi
1118 } else { // Miss
1119 _igvn.register_new_node_with_optimizer(phi1);
1120 }
1121 Node *hit2 = _igvn.hash_find_insert(phi2);
1122 if( hit2 ) { // Hit, toss just made Phi
1123 _igvn.remove_dead_node(phi2); // Remove new phi
1124 assert( hit2->is_Phi(), "" );
1125 phi2 = (PhiNode*)hit2; // Use existing phi
1126 } else { // Miss
1127 _igvn.register_new_node_with_optimizer(phi2);
1128 }
1129 // Register Phis with loop/block info
1130 set_ctrl(phi1, phi->in(0));
1131 set_ctrl(phi2, phi->in(0));
1132 // Make a new Cmp
1133 Node *cmp = sample_cmp->clone();
1134 cmp->set_req( 1, phi1 );
1135 cmp->set_req( 2, phi2 );
1136 _igvn.register_new_node_with_optimizer(cmp);
1137 set_ctrl(cmp, phi->in(0));
1139 assert( cmp->is_Cmp(), "" );
1140 return (CmpNode*)cmp;
1141 }
1143 //------------------------------sink_use---------------------------------------
1144 // If 'use' was in the loop-exit block, it now needs to be sunk
1145 // below the post-loop merge point.
1146 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1147 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1148 set_ctrl(use, post_loop);
1149 for (DUIterator j = use->outs(); use->has_out(j); j++)
1150 sink_use(use->out(j), post_loop);
1151 }
1152 }
1154 //------------------------------clone_loop-------------------------------------
1155 //
1156 // C L O N E A L O O P B O D Y
1157 //
1158 // This is the basic building block of the loop optimizations. It clones an
1159 // entire loop body. It makes an old_new loop body mapping; with this mapping
1160 // you can find the new-loop equivalent to an old-loop node. All new-loop
1161 // nodes are exactly equal to their old-loop counterparts, all edges are the
1162 // same. All exits from the old-loop now have a RegionNode that merges the
1163 // equivalent new-loop path. This is true even for the normal "loop-exit"
1164 // condition. All uses of loop-invariant old-loop values now come from (one
1165 // or more) Phis that merge their new-loop equivalents.
1166 //
1167 // This operation leaves the graph in an illegal state: there are two valid
1168 // control edges coming from the loop pre-header to both loop bodies. I'll
1169 // definitely have to hack the graph after running this transform.
1170 //
1171 // From this building block I will further edit edges to perform loop peeling
1172 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1173 //
1174 // Parameter side_by_size_idom:
1175 // When side_by_size_idom is NULL, the dominator tree is constructed for
1176 // the clone loop to dominate the original. Used in construction of
1177 // pre-main-post loop sequence.
1178 // When nonnull, the clone and original are side-by-side, both are
1179 // dominated by the side_by_side_idom node. Used in construction of
1180 // unswitched loops.
1181 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1182 Node* side_by_side_idom) {
1184 // Step 1: Clone the loop body. Make the old->new mapping.
1185 uint i;
1186 for( i = 0; i < loop->_body.size(); i++ ) {
1187 Node *old = loop->_body.at(i);
1188 Node *nnn = old->clone();
1189 old_new.map( old->_idx, nnn );
1190 _igvn.register_new_node_with_optimizer(nnn);
1191 }
1194 // Step 2: Fix the edges in the new body. If the old input is outside the
1195 // loop use it. If the old input is INside the loop, use the corresponding
1196 // new node instead.
1197 for( i = 0; i < loop->_body.size(); i++ ) {
1198 Node *old = loop->_body.at(i);
1199 Node *nnn = old_new[old->_idx];
1200 // Fix CFG/Loop controlling the new node
1201 if (has_ctrl(old)) {
1202 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1203 } else {
1204 set_loop(nnn, loop->_parent);
1205 if (old->outcnt() > 0) {
1206 set_idom( nnn, old_new[idom(old)->_idx], dd );
1207 }
1208 }
1209 // Correct edges to the new node
1210 for( uint j = 0; j < nnn->req(); j++ ) {
1211 Node *n = nnn->in(j);
1212 if( n ) {
1213 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1214 if( loop->is_member( old_in_loop ) )
1215 nnn->set_req(j, old_new[n->_idx]);
1216 }
1217 }
1218 _igvn.hash_find_insert(nnn);
1219 }
1220 Node *newhead = old_new[loop->_head->_idx];
1221 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1224 // Step 3: Now fix control uses. Loop varying control uses have already
1225 // been fixed up (as part of all input edges in Step 2). Loop invariant
1226 // control uses must be either an IfFalse or an IfTrue. Make a merge
1227 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1228 // refer to this.
1229 ResourceArea *area = Thread::current()->resource_area();
1230 Node_List worklist(area);
1231 uint new_counter = C->unique();
1232 for( i = 0; i < loop->_body.size(); i++ ) {
1233 Node* old = loop->_body.at(i);
1234 if( !old->is_CFG() ) continue;
1235 Node* nnn = old_new[old->_idx];
1237 // Copy uses to a worklist, so I can munge the def-use info
1238 // with impunity.
1239 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1240 worklist.push(old->fast_out(j));
1242 while( worklist.size() ) { // Visit all uses
1243 Node *use = worklist.pop();
1244 if (!has_node(use)) continue; // Ignore dead nodes
1245 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1246 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1247 // Both OLD and USE are CFG nodes here.
1248 assert( use->is_Proj(), "" );
1250 // Clone the loop exit control projection
1251 Node *newuse = use->clone();
1252 newuse->set_req(0,nnn);
1253 _igvn.register_new_node_with_optimizer(newuse);
1254 set_loop(newuse, use_loop);
1255 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1257 // We need a Region to merge the exit from the peeled body and the
1258 // exit from the old loop body.
1259 RegionNode *r = new (C, 3) RegionNode(3);
1260 // Map the old use to the new merge point
1261 old_new.map( use->_idx, r );
1262 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1263 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1265 // The original user of 'use' uses 'r' instead.
1266 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1267 Node* useuse = use->last_out(l);
1268 _igvn.hash_delete(useuse);
1269 _igvn._worklist.push(useuse);
1270 uint uses_found = 0;
1271 if( useuse->in(0) == use ) {
1272 useuse->set_req(0, r);
1273 uses_found++;
1274 if( useuse->is_CFG() ) {
1275 assert( dom_depth(useuse) > dd_r, "" );
1276 set_idom(useuse, r, dom_depth(useuse));
1277 }
1278 }
1279 for( uint k = 1; k < useuse->req(); k++ ) {
1280 if( useuse->in(k) == use ) {
1281 useuse->set_req(k, r);
1282 uses_found++;
1283 }
1284 }
1285 l -= uses_found; // we deleted 1 or more copies of this edge
1286 }
1288 // Now finish up 'r'
1289 r->set_req( 1, newuse );
1290 r->set_req( 2, use );
1291 _igvn.register_new_node_with_optimizer(r);
1292 set_loop(r, use_loop);
1293 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1294 } // End of if a loop-exit test
1295 }
1296 }
1298 // Step 4: If loop-invariant use is not control, it must be dominated by a
1299 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1300 // there if needed. Make a Phi there merging old and new used values.
1301 Node_List *split_if_set = NULL;
1302 Node_List *split_bool_set = NULL;
1303 Node_List *split_cex_set = NULL;
1304 for( i = 0; i < loop->_body.size(); i++ ) {
1305 Node* old = loop->_body.at(i);
1306 Node* nnn = old_new[old->_idx];
1307 // Copy uses to a worklist, so I can munge the def-use info
1308 // with impunity.
1309 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1310 worklist.push(old->fast_out(j));
1312 while( worklist.size() ) {
1313 Node *use = worklist.pop();
1314 if (!has_node(use)) continue; // Ignore dead nodes
1315 if (use->in(0) == C->top()) continue;
1316 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1317 // Check for data-use outside of loop - at least one of OLD or USE
1318 // must not be a CFG node.
1319 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1321 // If the Data use is an IF, that means we have an IF outside of the
1322 // loop that is switching on a condition that is set inside of the
1323 // loop. Happens if people set a loop-exit flag; then test the flag
1324 // in the loop to break the loop, then test is again outside of the
1325 // loop to determine which way the loop exited.
1326 if( use->is_If() || use->is_CMove() ) {
1327 // Since this code is highly unlikely, we lazily build the worklist
1328 // of such Nodes to go split.
1329 if( !split_if_set )
1330 split_if_set = new Node_List(area);
1331 split_if_set->push(use);
1332 }
1333 if( use->is_Bool() ) {
1334 if( !split_bool_set )
1335 split_bool_set = new Node_List(area);
1336 split_bool_set->push(use);
1337 }
1338 if( use->Opcode() == Op_CreateEx ) {
1339 if( !split_cex_set )
1340 split_cex_set = new Node_List(area);
1341 split_cex_set->push(use);
1342 }
1345 // Get "block" use is in
1346 uint idx = 0;
1347 while( use->in(idx) != old ) idx++;
1348 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1349 assert( !loop->is_member( get_loop( prev ) ), "" );
1350 Node *cfg = prev->_idx >= new_counter
1351 ? prev->in(2)
1352 : idom(prev);
1353 if( use->is_Phi() ) // Phi use is in prior block
1354 cfg = prev->in(idx); // NOT in block of Phi itself
1355 if (cfg->is_top()) { // Use is dead?
1356 _igvn.hash_delete(use);
1357 _igvn._worklist.push(use);
1358 use->set_req(idx, C->top());
1359 continue;
1360 }
1362 while( !loop->is_member( get_loop( cfg ) ) ) {
1363 prev = cfg;
1364 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1365 }
1366 // If the use occurs after merging several exits from the loop, then
1367 // old value must have dominated all those exits. Since the same old
1368 // value was used on all those exits we did not need a Phi at this
1369 // merge point. NOW we do need a Phi here. Each loop exit value
1370 // is now merged with the peeled body exit; each exit gets its own
1371 // private Phi and those Phis need to be merged here.
1372 Node *phi;
1373 if( prev->is_Region() ) {
1374 if( idx == 0 ) { // Updating control edge?
1375 phi = prev; // Just use existing control
1376 } else { // Else need a new Phi
1377 phi = PhiNode::make( prev, old );
1378 // Now recursively fix up the new uses of old!
1379 for( uint i = 1; i < prev->req(); i++ ) {
1380 worklist.push(phi); // Onto worklist once for each 'old' input
1381 }
1382 }
1383 } else {
1384 // Get new RegionNode merging old and new loop exits
1385 prev = old_new[prev->_idx];
1386 assert( prev, "just made this in step 7" );
1387 if( idx == 0 ) { // Updating control edge?
1388 phi = prev; // Just use existing control
1389 } else { // Else need a new Phi
1390 // Make a new Phi merging data values properly
1391 phi = PhiNode::make( prev, old );
1392 phi->set_req( 1, nnn );
1393 }
1394 }
1395 // If inserting a new Phi, check for prior hits
1396 if( idx != 0 ) {
1397 Node *hit = _igvn.hash_find_insert(phi);
1398 if( hit == NULL ) {
1399 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1400 } else { // or
1401 // Remove the new phi from the graph and use the hit
1402 _igvn.remove_dead_node(phi);
1403 phi = hit; // Use existing phi
1404 }
1405 set_ctrl(phi, prev);
1406 }
1407 // Make 'use' use the Phi instead of the old loop body exit value
1408 _igvn.hash_delete(use);
1409 _igvn._worklist.push(use);
1410 use->set_req(idx, phi);
1411 if( use->_idx >= new_counter ) { // If updating new phis
1412 // Not needed for correctness, but prevents a weak assert
1413 // in AddPNode from tripping (when we end up with different
1414 // base & derived Phis that will become the same after
1415 // IGVN does CSE).
1416 Node *hit = _igvn.hash_find_insert(use);
1417 if( hit ) // Go ahead and re-hash for hits.
1418 _igvn.subsume_node( use, hit );
1419 }
1421 // If 'use' was in the loop-exit block, it now needs to be sunk
1422 // below the post-loop merge point.
1423 sink_use( use, prev );
1424 }
1425 }
1426 }
1428 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1429 // the loop uses a condition set in the loop. The original IF probably
1430 // takes control from one or more OLD Regions (which in turn get from NEW
1431 // Regions). In any case, there will be a set of Phis for each merge point
1432 // from the IF up to where the original BOOL def exists the loop.
1433 if( split_if_set ) {
1434 while( split_if_set->size() ) {
1435 Node *iff = split_if_set->pop();
1436 if( iff->in(1)->is_Phi() ) {
1437 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1438 _igvn.hash_delete(iff);
1439 _igvn._worklist.push(iff);
1440 iff->set_req(1, b);
1441 }
1442 }
1443 }
1444 if( split_bool_set ) {
1445 while( split_bool_set->size() ) {
1446 Node *b = split_bool_set->pop();
1447 Node *phi = b->in(1);
1448 assert( phi->is_Phi(), "" );
1449 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1450 _igvn.hash_delete(b);
1451 _igvn._worklist.push(b);
1452 b->set_req(1, cmp);
1453 }
1454 }
1455 if( split_cex_set ) {
1456 while( split_cex_set->size() ) {
1457 Node *b = split_cex_set->pop();
1458 assert( b->in(0)->is_Region(), "" );
1459 assert( b->in(1)->is_Phi(), "" );
1460 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1461 split_up( b, b->in(0), NULL );
1462 }
1463 }
1465 }
1468 //---------------------- stride_of_possible_iv -------------------------------------
1469 // Looks for an iff/bool/comp with one operand of the compare
1470 // being a cycle involving an add and a phi,
1471 // with an optional truncation (left-shift followed by a right-shift)
1472 // of the add. Returns zero if not an iv.
1473 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1474 Node* trunc1 = NULL;
1475 Node* trunc2 = NULL;
1476 const TypeInt* ttype = NULL;
1477 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1478 return 0;
1479 }
1480 BoolNode* bl = iff->in(1)->as_Bool();
1481 Node* cmp = bl->in(1);
1482 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1483 return 0;
1484 }
1485 // Must have an invariant operand
1486 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1487 return 0;
1488 }
1489 Node* add2 = NULL;
1490 Node* cmp1 = cmp->in(1);
1491 if (cmp1->is_Phi()) {
1492 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1493 Node* phi = cmp1;
1494 for (uint i = 1; i < phi->req(); i++) {
1495 Node* in = phi->in(i);
1496 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1497 &trunc1, &trunc2, &ttype);
1498 if (add && add->in(1) == phi) {
1499 add2 = add->in(2);
1500 break;
1501 }
1502 }
1503 } else {
1504 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1505 Node* addtrunc = cmp1;
1506 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1507 &trunc1, &trunc2, &ttype);
1508 if (add && add->in(1)->is_Phi()) {
1509 Node* phi = add->in(1);
1510 for (uint i = 1; i < phi->req(); i++) {
1511 if (phi->in(i) == addtrunc) {
1512 add2 = add->in(2);
1513 break;
1514 }
1515 }
1516 }
1517 }
1518 if (add2 != NULL) {
1519 const TypeInt* add2t = _igvn.type(add2)->is_int();
1520 if (add2t->is_con()) {
1521 return add2t->get_con();
1522 }
1523 }
1524 return 0;
1525 }
1528 //---------------------- stay_in_loop -------------------------------------
1529 // Return the (unique) control output node that's in the loop (if it exists.)
1530 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1531 Node* unique = NULL;
1532 if (!n) return NULL;
1533 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1534 Node* use = n->fast_out(i);
1535 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1536 if (unique != NULL) {
1537 return NULL;
1538 }
1539 unique = use;
1540 }
1541 }
1542 return unique;
1543 }
1545 //------------------------------ register_node -------------------------------------
1546 // Utility to register node "n" with PhaseIdealLoop
1547 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1548 _igvn.register_new_node_with_optimizer(n);
1549 loop->_body.push(n);
1550 if (n->is_CFG()) {
1551 set_loop(n, loop);
1552 set_idom(n, pred, ddepth);
1553 } else {
1554 set_ctrl(n, pred);
1555 }
1556 }
1558 //------------------------------ proj_clone -------------------------------------
1559 // Utility to create an if-projection
1560 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1561 ProjNode* c = p->clone()->as_Proj();
1562 c->set_req(0, iff);
1563 return c;
1564 }
1566 //------------------------------ short_circuit_if -------------------------------------
1567 // Force the iff control output to be the live_proj
1568 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1569 int proj_con = live_proj->_con;
1570 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1571 Node *con = _igvn.intcon(proj_con);
1572 set_ctrl(con, C->root());
1573 if (iff) {
1574 iff->set_req(1, con);
1575 }
1576 return con;
1577 }
1579 //------------------------------ insert_if_before_proj -------------------------------------
1580 // Insert a new if before an if projection (* - new node)
1581 //
1582 // before
1583 // if(test)
1584 // / \
1585 // v v
1586 // other-proj proj (arg)
1587 //
1588 // after
1589 // if(test)
1590 // / \
1591 // / v
1592 // | * proj-clone
1593 // v |
1594 // other-proj v
1595 // * new_if(relop(cmp[IU](left,right)))
1596 // / \
1597 // v v
1598 // * new-proj proj
1599 // (returned)
1600 //
1601 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1602 IfNode* iff = proj->in(0)->as_If();
1603 IdealLoopTree *loop = get_loop(proj);
1604 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1605 int ddepth = dom_depth(proj);
1607 _igvn.hash_delete(iff);
1608 _igvn._worklist.push(iff);
1609 _igvn.hash_delete(proj);
1610 _igvn._worklist.push(proj);
1612 proj->set_req(0, NULL); // temporary disconnect
1613 ProjNode* proj2 = proj_clone(proj, iff);
1614 register_node(proj2, loop, iff, ddepth);
1616 Node* cmp = Signed ? (Node*) new (C,3)CmpINode(left, right) : (Node*) new (C,3)CmpUNode(left, right);
1617 register_node(cmp, loop, proj2, ddepth);
1619 BoolNode* bol = new (C,2)BoolNode(cmp, relop);
1620 register_node(bol, loop, proj2, ddepth);
1622 IfNode* new_if = new (C,2)IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1623 register_node(new_if, loop, proj2, ddepth);
1625 proj->set_req(0, new_if); // reattach
1626 set_idom(proj, new_if, ddepth);
1628 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1629 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1631 return new_exit;
1632 }
1634 //------------------------------ insert_region_before_proj -------------------------------------
1635 // Insert a region before an if projection (* - new node)
1636 //
1637 // before
1638 // if(test)
1639 // / |
1640 // v |
1641 // proj v
1642 // other-proj
1643 //
1644 // after
1645 // if(test)
1646 // / |
1647 // v |
1648 // * proj-clone v
1649 // | other-proj
1650 // v
1651 // * new-region
1652 // |
1653 // v
1654 // * dum_if
1655 // / \
1656 // v \
1657 // * dum-proj v
1658 // proj
1659 //
1660 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1661 IfNode* iff = proj->in(0)->as_If();
1662 IdealLoopTree *loop = get_loop(proj);
1663 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1664 int ddepth = dom_depth(proj);
1666 _igvn.hash_delete(iff);
1667 _igvn._worklist.push(iff);
1668 _igvn.hash_delete(proj);
1669 _igvn._worklist.push(proj);
1671 proj->set_req(0, NULL); // temporary disconnect
1672 ProjNode* proj2 = proj_clone(proj, iff);
1673 register_node(proj2, loop, iff, ddepth);
1675 RegionNode* reg = new (C,2)RegionNode(2);
1676 reg->set_req(1, proj2);
1677 register_node(reg, loop, iff, ddepth);
1679 IfNode* dum_if = new (C,2)IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
1680 register_node(dum_if, loop, reg, ddepth);
1682 proj->set_req(0, dum_if); // reattach
1683 set_idom(proj, dum_if, ddepth);
1685 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
1686 register_node(dum_proj, loop, dum_if, ddepth);
1688 return reg;
1689 }
1691 //------------------------------ insert_cmpi_loop_exit -------------------------------------
1692 // Clone a signed compare loop exit from an unsigned compare and
1693 // insert it before the unsigned cmp on the stay-in-loop path.
1694 // All new nodes inserted in the dominator tree between the original
1695 // if and it's projections. The original if test is replaced with
1696 // a constant to force the stay-in-loop path.
1697 //
1698 // This is done to make sure that the original if and it's projections
1699 // still dominate the same set of control nodes, that the ctrl() relation
1700 // from data nodes to them is preserved, and that their loop nesting is
1701 // preserved.
1702 //
1703 // before
1704 // if(i <u limit) unsigned compare loop exit
1705 // / |
1706 // v v
1707 // exit-proj stay-in-loop-proj
1708 //
1709 // after
1710 // if(stay-in-loop-const) original if
1711 // / |
1712 // / v
1713 // / if(i < limit) new signed test
1714 // / / |
1715 // / / v
1716 // / / if(i <u limit) new cloned unsigned test
1717 // / / / |
1718 // v v v |
1719 // region |
1720 // | |
1721 // dum-if |
1722 // / | |
1723 // ether | |
1724 // v v
1725 // exit-proj stay-in-loop-proj
1726 //
1727 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
1728 const bool Signed = true;
1729 const bool Unsigned = false;
1731 BoolNode* bol = if_cmpu->in(1)->as_Bool();
1732 if (bol->_test._test != BoolTest::lt) return NULL;
1733 CmpNode* cmpu = bol->in(1)->as_Cmp();
1734 if (cmpu->Opcode() != Op_CmpU) return NULL;
1735 int stride = stride_of_possible_iv(if_cmpu);
1736 if (stride == 0) return NULL;
1738 ProjNode* lp_continue = stay_in_loop(if_cmpu, loop)->as_Proj();
1739 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
1741 Node* limit = NULL;
1742 if (stride > 0) {
1743 limit = cmpu->in(2);
1744 } else {
1745 limit = _igvn.makecon(TypeInt::ZERO);
1746 set_ctrl(limit, C->root());
1747 }
1748 // Create a new region on the exit path
1749 RegionNode* reg = insert_region_before_proj(lp_exit);
1751 // Clone the if-cmpu-true-false using a signed compare
1752 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
1753 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
1754 reg->add_req(cmpi_exit);
1756 // Clone the if-cmpu-true-false
1757 BoolTest::mask rel_u = bol->_test._test;
1758 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
1759 reg->add_req(cmpu_exit);
1761 // Force original if to stay in loop.
1762 short_circuit_if(if_cmpu, lp_continue);
1764 return cmpi_exit->in(0)->as_If();
1765 }
1767 //------------------------------ remove_cmpi_loop_exit -------------------------------------
1768 // Remove a previously inserted signed compare loop exit.
1769 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
1770 Node* lp_proj = stay_in_loop(if_cmp, loop);
1771 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
1772 stay_in_loop(lp_proj, loop)->is_If() &&
1773 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
1774 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
1775 set_ctrl(con, C->root());
1776 if_cmp->set_req(1, con);
1777 }
1779 //------------------------------ scheduled_nodelist -------------------------------------
1780 // Create a post order schedule of nodes that are in the
1781 // "member" set. The list is returned in "sched".
1782 // The first node in "sched" is the loop head, followed by
1783 // nodes which have no inputs in the "member" set, and then
1784 // followed by the nodes that have an immediate input dependence
1785 // on a node in "sched".
1786 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
1788 assert(member.test(loop->_head->_idx), "loop head must be in member set");
1789 Arena *a = Thread::current()->resource_area();
1790 VectorSet visited(a);
1791 Node_Stack nstack(a, loop->_body.size());
1793 Node* n = loop->_head; // top of stack is cached in "n"
1794 uint idx = 0;
1795 visited.set(n->_idx);
1797 // Initially push all with no inputs from within member set
1798 for(uint i = 0; i < loop->_body.size(); i++ ) {
1799 Node *elt = loop->_body.at(i);
1800 if (member.test(elt->_idx)) {
1801 bool found = false;
1802 for (uint j = 0; j < elt->req(); j++) {
1803 Node* def = elt->in(j);
1804 if (def && member.test(def->_idx) && def != elt) {
1805 found = true;
1806 break;
1807 }
1808 }
1809 if (!found && elt != loop->_head) {
1810 nstack.push(n, idx);
1811 n = elt;
1812 assert(!visited.test(n->_idx), "not seen yet");
1813 visited.set(n->_idx);
1814 }
1815 }
1816 }
1818 // traverse out's that are in the member set
1819 while (true) {
1820 if (idx < n->outcnt()) {
1821 Node* use = n->raw_out(idx);
1822 idx++;
1823 if (!visited.test_set(use->_idx)) {
1824 if (member.test(use->_idx)) {
1825 nstack.push(n, idx);
1826 n = use;
1827 idx = 0;
1828 }
1829 }
1830 } else {
1831 // All outputs processed
1832 sched.push(n);
1833 if (nstack.is_empty()) break;
1834 n = nstack.node();
1835 idx = nstack.index();
1836 nstack.pop();
1837 }
1838 }
1839 }
1842 //------------------------------ has_use_in_set -------------------------------------
1843 // Has a use in the vector set
1844 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
1845 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1846 Node* use = n->fast_out(j);
1847 if (vset.test(use->_idx)) {
1848 return true;
1849 }
1850 }
1851 return false;
1852 }
1855 //------------------------------ has_use_internal_to_set -------------------------------------
1856 // Has use internal to the vector set (ie. not in a phi at the loop head)
1857 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
1858 Node* head = loop->_head;
1859 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1860 Node* use = n->fast_out(j);
1861 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
1862 return true;
1863 }
1864 }
1865 return false;
1866 }
1869 //------------------------------ clone_for_use_outside_loop -------------------------------------
1870 // clone "n" for uses that are outside of loop
1871 void PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
1873 assert(worklist.size() == 0, "should be empty");
1874 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1875 Node* use = n->fast_out(j);
1876 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
1877 worklist.push(use);
1878 }
1879 }
1880 while( worklist.size() ) {
1881 Node *use = worklist.pop();
1882 if (!has_node(use) || use->in(0) == C->top()) continue;
1883 uint j;
1884 for (j = 0; j < use->req(); j++) {
1885 if (use->in(j) == n) break;
1886 }
1887 assert(j < use->req(), "must be there");
1889 // clone "n" and insert it between the inputs of "n" and the use outside the loop
1890 Node* n_clone = n->clone();
1891 _igvn.hash_delete(use);
1892 use->set_req(j, n_clone);
1893 _igvn._worklist.push(use);
1894 if (!use->is_Phi()) {
1895 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
1896 set_ctrl(n_clone, use_c);
1897 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
1898 get_loop(use_c)->_body.push(n_clone);
1899 } else {
1900 // Use in a phi is considered a use in the associated predecessor block
1901 Node *prevbb = use->in(0)->in(j);
1902 set_ctrl(n_clone, prevbb);
1903 assert(!loop->is_member(get_loop(prevbb)), "should be outside loop");
1904 get_loop(prevbb)->_body.push(n_clone);
1905 }
1906 _igvn.register_new_node_with_optimizer(n_clone);
1907 #if !defined(PRODUCT)
1908 if (TracePartialPeeling) {
1909 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
1910 }
1911 #endif
1912 }
1913 }
1916 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
1917 // clone "n" for special uses that are in the not_peeled region.
1918 // If these def-uses occur in separate blocks, the code generator
1919 // marks the method as not compilable. For example, if a "BoolNode"
1920 // is in a different basic block than the "IfNode" that uses it, then
1921 // the compilation is aborted in the code generator.
1922 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1923 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
1924 if (n->is_Phi() || n->is_Load()) {
1925 return;
1926 }
1927 assert(worklist.size() == 0, "should be empty");
1928 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1929 Node* use = n->fast_out(j);
1930 if ( not_peel.test(use->_idx) &&
1931 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
1932 use->in(1) == n) {
1933 worklist.push(use);
1934 }
1935 }
1936 if (worklist.size() > 0) {
1937 // clone "n" and insert it between inputs of "n" and the use
1938 Node* n_clone = n->clone();
1939 loop->_body.push(n_clone);
1940 _igvn.register_new_node_with_optimizer(n_clone);
1941 set_ctrl(n_clone, get_ctrl(n));
1942 sink_list.push(n_clone);
1943 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
1944 #if !defined(PRODUCT)
1945 if (TracePartialPeeling) {
1946 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
1947 }
1948 #endif
1949 while( worklist.size() ) {
1950 Node *use = worklist.pop();
1951 _igvn.hash_delete(use);
1952 _igvn._worklist.push(use);
1953 for (uint j = 1; j < use->req(); j++) {
1954 if (use->in(j) == n) {
1955 use->set_req(j, n_clone);
1956 }
1957 }
1958 }
1959 }
1960 }
1963 //------------------------------ insert_phi_for_loop -------------------------------------
1964 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1965 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
1966 Node *phi = PhiNode::make(lp, back_edge_val);
1967 phi->set_req(LoopNode::EntryControl, lp_entry_val);
1968 // Use existing phi if it already exists
1969 Node *hit = _igvn.hash_find_insert(phi);
1970 if( hit == NULL ) {
1971 _igvn.register_new_node_with_optimizer(phi);
1972 set_ctrl(phi, lp);
1973 } else {
1974 // Remove the new phi from the graph and use the hit
1975 _igvn.remove_dead_node(phi);
1976 phi = hit;
1977 }
1978 _igvn.hash_delete(use);
1979 _igvn._worklist.push(use);
1980 use->set_req(idx, phi);
1981 }
1983 #ifdef ASSERT
1984 //------------------------------ is_valid_loop_partition -------------------------------------
1985 // Validate the loop partition sets: peel and not_peel
1986 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
1987 VectorSet& not_peel ) {
1988 uint i;
1989 // Check that peel_list entries are in the peel set
1990 for (i = 0; i < peel_list.size(); i++) {
1991 if (!peel.test(peel_list.at(i)->_idx)) {
1992 return false;
1993 }
1994 }
1995 // Check at loop members are in one of peel set or not_peel set
1996 for (i = 0; i < loop->_body.size(); i++ ) {
1997 Node *def = loop->_body.at(i);
1998 uint di = def->_idx;
1999 // Check that peel set elements are in peel_list
2000 if (peel.test(di)) {
2001 if (not_peel.test(di)) {
2002 return false;
2003 }
2004 // Must be in peel_list also
2005 bool found = false;
2006 for (uint j = 0; j < peel_list.size(); j++) {
2007 if (peel_list.at(j)->_idx == di) {
2008 found = true;
2009 break;
2010 }
2011 }
2012 if (!found) {
2013 return false;
2014 }
2015 } else if (not_peel.test(di)) {
2016 if (peel.test(di)) {
2017 return false;
2018 }
2019 } else {
2020 return false;
2021 }
2022 }
2023 return true;
2024 }
2026 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2027 // Ensure a use outside of loop is of the right form
2028 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2029 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2030 return (use->is_Phi() &&
2031 use_c->is_Region() && use_c->req() == 3 &&
2032 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2033 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2034 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2035 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2036 }
2038 //------------------------------ is_valid_clone_loop_form -------------------------------------
2039 // Ensure that all uses outside of loop are of the right form
2040 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2041 uint orig_exit_idx, uint clone_exit_idx) {
2042 uint len = peel_list.size();
2043 for (uint i = 0; i < len; i++) {
2044 Node *def = peel_list.at(i);
2046 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2047 Node *use = def->fast_out(j);
2048 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2049 if (!loop->is_member(get_loop(use_c))) {
2050 // use is not in the loop, check for correct structure
2051 if (use->in(0) == def) {
2052 // Okay
2053 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2054 return false;
2055 }
2056 }
2057 }
2058 }
2059 return true;
2060 }
2061 #endif
2063 //------------------------------ partial_peel -------------------------------------
2064 // Partially peel (aka loop rotation) the top portion of a loop (called
2065 // the peel section below) by cloning it and placing one copy just before
2066 // the new loop head and the other copy at the bottom of the new loop.
2067 //
2068 // before after where it came from
2069 //
2070 // stmt1 stmt1
2071 // loop: stmt2 clone
2072 // stmt2 if condA goto exitA clone
2073 // if condA goto exitA new_loop: new
2074 // stmt3 stmt3 clone
2075 // if !condB goto loop if condB goto exitB clone
2076 // exitB: stmt2 orig
2077 // stmt4 if !condA goto new_loop orig
2078 // exitA: goto exitA
2079 // exitB:
2080 // stmt4
2081 // exitA:
2082 //
2083 // Step 1: find the cut point: an exit test on probable
2084 // induction variable.
2085 // Step 2: schedule (with cloning) operations in the peel
2086 // section that can be executed after the cut into
2087 // the section that is not peeled. This may need
2088 // to clone operations into exit blocks. For
2089 // instance, a reference to A[i] in the not-peel
2090 // section and a reference to B[i] in an exit block
2091 // may cause a left-shift of i by 2 to be placed
2092 // in the peel block. This step will clone the left
2093 // shift into the exit block and sink the left shift
2094 // from the peel to the not-peel section.
2095 // Step 3: clone the loop, retarget the control, and insert
2096 // phis for values that are live across the new loop
2097 // head. This is very dependent on the graph structure
2098 // from clone_loop. It creates region nodes for
2099 // exit control and associated phi nodes for values
2100 // flow out of the loop through that exit. The region
2101 // node is dominated by the clone's control projection.
2102 // So the clone's peel section is placed before the
2103 // new loop head, and the clone's not-peel section is
2104 // forms the top part of the new loop. The original
2105 // peel section forms the tail of the new loop.
2106 // Step 4: update the dominator tree and recompute the
2107 // dominator depth.
2108 //
2109 // orig
2110 //
2111 // stmt1
2112 // |
2113 // v
2114 // loop<----+
2115 // | |
2116 // stmt2 |
2117 // | |
2118 // v |
2119 // ifA |
2120 // / | |
2121 // v v |
2122 // false true ^ <-- last_peel
2123 // / | |
2124 // / ===|==cut |
2125 // / stmt3 | <-- first_not_peel
2126 // / | |
2127 // | v |
2128 // v ifB |
2129 // exitA: / \ |
2130 // / \ |
2131 // v v |
2132 // false true |
2133 // / \ |
2134 // / ----+
2135 // |
2136 // v
2137 // exitB:
2138 // stmt4
2139 //
2140 //
2141 // after clone loop
2142 //
2143 // stmt1
2144 // / \
2145 // clone / \ orig
2146 // / \
2147 // / \
2148 // v v
2149 // +---->loop loop<----+
2150 // | | | |
2151 // | stmt2 stmt2 |
2152 // | | | |
2153 // | v v |
2154 // | ifA ifA |
2155 // | | \ / | |
2156 // | v v v v |
2157 // ^ true false false true ^ <-- last_peel
2158 // | | ^ \ / | |
2159 // | cut==|== \ \ / ===|==cut |
2160 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2161 // | | dom | | | |
2162 // | v \ 1v v2 v |
2163 // | ifB regionA ifB |
2164 // | / \ | / \ |
2165 // | / \ v / \ |
2166 // | v v exitA: v v |
2167 // | true false false true |
2168 // | / ^ \ / \ |
2169 // +---- \ \ / ----+
2170 // dom \ /
2171 // \ 1v v2
2172 // regionB
2173 // |
2174 // v
2175 // exitB:
2176 // stmt4
2177 //
2178 //
2179 // after partial peel
2180 //
2181 // stmt1
2182 // /
2183 // clone / orig
2184 // / TOP
2185 // / \
2186 // v v
2187 // TOP->region region----+
2188 // | | |
2189 // stmt2 stmt2 |
2190 // | | |
2191 // v v |
2192 // ifA ifA |
2193 // | \ / | |
2194 // v v v v |
2195 // true false false true | <-- last_peel
2196 // | ^ \ / +------|---+
2197 // +->newloop \ \ / === ==cut | |
2198 // | stmt3 \ \ / TOP | |
2199 // | | dom | | stmt3 | | <-- first_not_peel
2200 // | v \ 1v v2 v | |
2201 // | ifB regionA ifB ^ v
2202 // | / \ | / \ | |
2203 // | / \ v / \ | |
2204 // | v v exitA: v v | |
2205 // | true false false true | |
2206 // | / ^ \ / \ | |
2207 // | | \ \ / v | |
2208 // | | dom \ / TOP | |
2209 // | | \ 1v v2 | |
2210 // ^ v regionB | |
2211 // | | | | |
2212 // | | v ^ v
2213 // | | exitB: | |
2214 // | | stmt4 | |
2215 // | +------------>-----------------+ |
2216 // | |
2217 // +-----------------<---------------------+
2218 //
2219 //
2220 // final graph
2221 //
2222 // stmt1
2223 // |
2224 // v
2225 // ........> ifA clone
2226 // : / |
2227 // dom / |
2228 // : v v
2229 // : false true
2230 // : | |
2231 // : | stmt2 clone
2232 // : | |
2233 // : | v
2234 // : | newloop<-----+
2235 // : | | |
2236 // : | stmt3 clone |
2237 // : | | |
2238 // : | v |
2239 // : | ifB |
2240 // : | / \ |
2241 // : | v v |
2242 // : | false true |
2243 // : | | | |
2244 // : | v stmt2 |
2245 // : | exitB: | |
2246 // : | stmt4 v |
2247 // : | ifA orig |
2248 // : | / \ |
2249 // : | / \ |
2250 // : | v v |
2251 // : | false true |
2252 // : | / \ |
2253 // : v v -----+
2254 // RegionA
2255 // |
2256 // v
2257 // exitA
2258 //
2259 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2261 if (!loop->_head->is_Loop()) {
2262 return false; }
2264 LoopNode *head = loop->_head->as_Loop();
2266 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2267 return false;
2268 }
2270 // Check for complex exit control
2271 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2272 Node *n = loop->_body.at(ii);
2273 int opc = n->Opcode();
2274 if (n->is_Call() ||
2275 opc == Op_Catch ||
2276 opc == Op_CatchProj ||
2277 opc == Op_Jump ||
2278 opc == Op_JumpProj) {
2279 #if !defined(PRODUCT)
2280 if (TracePartialPeeling) {
2281 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2282 }
2283 #endif
2284 return false;
2285 }
2286 }
2288 int dd = dom_depth(head);
2290 // Step 1: find cut point
2292 // Walk up dominators to loop head looking for first loop exit
2293 // which is executed on every path thru loop.
2294 IfNode *peel_if = NULL;
2295 IfNode *peel_if_cmpu = NULL;
2297 Node *iff = loop->tail();
2298 while( iff != head ) {
2299 if( iff->is_If() ) {
2300 Node *ctrl = get_ctrl(iff->in(1));
2301 if (ctrl->is_top()) return false; // Dead test on live IF.
2302 // If loop-varying exit-test, check for induction variable
2303 if( loop->is_member(get_loop(ctrl)) &&
2304 loop->is_loop_exit(iff) &&
2305 is_possible_iv_test(iff)) {
2306 Node* cmp = iff->in(1)->in(1);
2307 if (cmp->Opcode() == Op_CmpI) {
2308 peel_if = iff->as_If();
2309 } else {
2310 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2311 peel_if_cmpu = iff->as_If();
2312 }
2313 }
2314 }
2315 iff = idom(iff);
2316 }
2317 // Prefer signed compare over unsigned compare.
2318 IfNode* new_peel_if = NULL;
2319 if (peel_if == NULL) {
2320 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2321 return false; // No peel point found
2322 }
2323 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2324 if (new_peel_if == NULL) {
2325 return false; // No peel point found
2326 }
2327 peel_if = new_peel_if;
2328 }
2329 Node* last_peel = stay_in_loop(peel_if, loop);
2330 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2331 if (first_not_peeled == NULL || first_not_peeled == head) {
2332 return false;
2333 }
2335 #if !defined(PRODUCT)
2336 if (TracePartialPeeling) {
2337 tty->print_cr("before partial peel one iteration");
2338 Node_List wl;
2339 Node* t = head->in(2);
2340 while (true) {
2341 wl.push(t);
2342 if (t == head) break;
2343 t = idom(t);
2344 }
2345 while (wl.size() > 0) {
2346 Node* tt = wl.pop();
2347 tt->dump();
2348 if (tt == last_peel) tty->print_cr("-- cut --");
2349 }
2350 }
2351 #endif
2352 ResourceArea *area = Thread::current()->resource_area();
2353 VectorSet peel(area);
2354 VectorSet not_peel(area);
2355 Node_List peel_list(area);
2356 Node_List worklist(area);
2357 Node_List sink_list(area);
2359 // Set of cfg nodes to peel are those that are executable from
2360 // the head through last_peel.
2361 assert(worklist.size() == 0, "should be empty");
2362 worklist.push(head);
2363 peel.set(head->_idx);
2364 while (worklist.size() > 0) {
2365 Node *n = worklist.pop();
2366 if (n != last_peel) {
2367 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2368 Node* use = n->fast_out(j);
2369 if (use->is_CFG() &&
2370 loop->is_member(get_loop(use)) &&
2371 !peel.test_set(use->_idx)) {
2372 worklist.push(use);
2373 }
2374 }
2375 }
2376 }
2378 // Set of non-cfg nodes to peel are those that are control
2379 // dependent on the cfg nodes.
2380 uint i;
2381 for(i = 0; i < loop->_body.size(); i++ ) {
2382 Node *n = loop->_body.at(i);
2383 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2384 if (peel.test(n_c->_idx)) {
2385 peel.set(n->_idx);
2386 } else {
2387 not_peel.set(n->_idx);
2388 }
2389 }
2391 // Step 2: move operations from the peeled section down into the
2392 // not-peeled section
2394 // Get a post order schedule of nodes in the peel region
2395 // Result in right-most operand.
2396 scheduled_nodelist(loop, peel, peel_list );
2398 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2400 // For future check for too many new phis
2401 uint old_phi_cnt = 0;
2402 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2403 Node* use = head->fast_out(j);
2404 if (use->is_Phi()) old_phi_cnt++;
2405 }
2407 #if !defined(PRODUCT)
2408 if (TracePartialPeeling) {
2409 tty->print_cr("\npeeled list");
2410 }
2411 #endif
2413 // Evacuate nodes in peel region into the not_peeled region if possible
2414 uint new_phi_cnt = 0;
2415 for (i = 0; i < peel_list.size();) {
2416 Node* n = peel_list.at(i);
2417 #if !defined(PRODUCT)
2418 if (TracePartialPeeling) n->dump();
2419 #endif
2420 bool incr = true;
2421 if ( !n->is_CFG() ) {
2423 if ( has_use_in_set(n, not_peel) ) {
2425 // If not used internal to the peeled region,
2426 // move "n" from peeled to not_peeled region.
2428 if ( !has_use_internal_to_set(n, peel, loop) ) {
2430 // if not pinned and not a load (which maybe anti-dependent on a store)
2431 // and not a CMove (Matcher expects only bool->cmove).
2432 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2433 clone_for_use_outside_loop( loop, n, worklist );
2435 sink_list.push(n);
2436 peel >>= n->_idx; // delete n from peel set.
2437 not_peel <<= n->_idx; // add n to not_peel set.
2438 peel_list.remove(i);
2439 incr = false;
2440 #if !defined(PRODUCT)
2441 if (TracePartialPeeling) {
2442 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2443 n->_idx, get_ctrl(n)->_idx);
2444 }
2445 #endif
2446 }
2447 } else {
2448 // Otherwise check for special def-use cases that span
2449 // the peel/not_peel boundary such as bool->if
2450 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2451 new_phi_cnt++;
2452 }
2453 }
2454 }
2455 if (incr) i++;
2456 }
2458 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2459 #if !defined(PRODUCT)
2460 if (TracePartialPeeling) {
2461 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2462 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2463 }
2464 #endif
2465 if (new_peel_if != NULL) {
2466 remove_cmpi_loop_exit(new_peel_if, loop);
2467 }
2468 // Inhibit more partial peeling on this loop
2469 assert(!head->is_partial_peel_loop(), "not partial peeled");
2470 head->mark_partial_peel_failed();
2471 return false;
2472 }
2474 // Step 3: clone loop, retarget control, and insert new phis
2476 // Create new loop head for new phis and to hang
2477 // the nodes being moved (sinked) from the peel region.
2478 LoopNode* new_head = new (C, 3) LoopNode(last_peel, last_peel);
2479 _igvn.register_new_node_with_optimizer(new_head);
2480 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2481 first_not_peeled->set_req(0, new_head);
2482 set_loop(new_head, loop);
2483 loop->_body.push(new_head);
2484 not_peel.set(new_head->_idx);
2485 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2486 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2488 while (sink_list.size() > 0) {
2489 Node* n = sink_list.pop();
2490 set_ctrl(n, new_head);
2491 }
2493 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2495 clone_loop( loop, old_new, dd );
2497 const uint clone_exit_idx = 1;
2498 const uint orig_exit_idx = 2;
2499 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2501 Node* head_clone = old_new[head->_idx];
2502 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2503 Node* orig_tail_clone = head_clone->in(2);
2505 // Add phi if "def" node is in peel set and "use" is not
2507 for(i = 0; i < peel_list.size(); i++ ) {
2508 Node *def = peel_list.at(i);
2509 if (!def->is_CFG()) {
2510 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2511 Node *use = def->fast_out(j);
2512 if (has_node(use) && use->in(0) != C->top() &&
2513 (!peel.test(use->_idx) ||
2514 (use->is_Phi() && use->in(0) == head)) ) {
2515 worklist.push(use);
2516 }
2517 }
2518 while( worklist.size() ) {
2519 Node *use = worklist.pop();
2520 for (uint j = 1; j < use->req(); j++) {
2521 Node* n = use->in(j);
2522 if (n == def) {
2524 // "def" is in peel set, "use" is not in peel set
2525 // or "use" is in the entry boundary (a phi) of the peel set
2527 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2529 if ( loop->is_member(get_loop( use_c )) ) {
2530 // use is in loop
2531 if (old_new[use->_idx] != NULL) { // null for dead code
2532 Node* use_clone = old_new[use->_idx];
2533 _igvn.hash_delete(use);
2534 use->set_req(j, C->top());
2535 _igvn._worklist.push(use);
2536 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2537 }
2538 } else {
2539 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2540 // use is not in the loop, check if the live range includes the cut
2541 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2542 if (not_peel.test(lp_if->_idx)) {
2543 assert(j == orig_exit_idx, "use from original loop");
2544 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2545 }
2546 }
2547 }
2548 }
2549 }
2550 }
2551 }
2553 // Step 3b: retarget control
2555 // Redirect control to the new loop head if a cloned node in
2556 // the not_peeled region has control that points into the peeled region.
2557 // This necessary because the cloned peeled region will be outside
2558 // the loop.
2559 // from to
2560 // cloned-peeled <---+
2561 // new_head_clone: | <--+
2562 // cloned-not_peeled in(0) in(0)
2563 // orig-peeled
2565 for(i = 0; i < loop->_body.size(); i++ ) {
2566 Node *n = loop->_body.at(i);
2567 if (!n->is_CFG() && n->in(0) != NULL &&
2568 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2569 Node* n_clone = old_new[n->_idx];
2570 _igvn.hash_delete(n_clone);
2571 n_clone->set_req(0, new_head_clone);
2572 _igvn._worklist.push(n_clone);
2573 }
2574 }
2576 // Backedge of the surviving new_head (the clone) is original last_peel
2577 _igvn.hash_delete(new_head_clone);
2578 new_head_clone->set_req(LoopNode::LoopBackControl, last_peel);
2579 _igvn._worklist.push(new_head_clone);
2581 // Cut first node in original not_peel set
2582 _igvn.hash_delete(new_head);
2583 new_head->set_req(LoopNode::EntryControl, C->top());
2584 new_head->set_req(LoopNode::LoopBackControl, C->top());
2585 _igvn._worklist.push(new_head);
2587 // Copy head_clone back-branch info to original head
2588 // and remove original head's loop entry and
2589 // clone head's back-branch
2590 _igvn.hash_delete(head);
2591 _igvn.hash_delete(head_clone);
2592 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2593 head->set_req(LoopNode::LoopBackControl, C->top());
2594 head_clone->set_req(LoopNode::LoopBackControl, C->top());
2595 _igvn._worklist.push(head);
2596 _igvn._worklist.push(head_clone);
2598 // Similarly modify the phis
2599 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2600 Node* use = head->fast_out(k);
2601 if (use->is_Phi() && use->outcnt() > 0) {
2602 Node* use_clone = old_new[use->_idx];
2603 _igvn.hash_delete(use);
2604 _igvn.hash_delete(use_clone);
2605 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2606 use->set_req(LoopNode::LoopBackControl, C->top());
2607 use_clone->set_req(LoopNode::LoopBackControl, C->top());
2608 _igvn._worklist.push(use);
2609 _igvn._worklist.push(use_clone);
2610 }
2611 }
2613 // Step 4: update dominator tree and dominator depth
2615 set_idom(head, orig_tail_clone, dd);
2616 recompute_dom_depth();
2618 // Inhibit more partial peeling on this loop
2619 new_head_clone->set_partial_peel_loop();
2620 C->set_major_progress();
2622 #if !defined(PRODUCT)
2623 if (TracePartialPeeling) {
2624 tty->print_cr("\nafter partial peel one iteration");
2625 Node_List wl(area);
2626 Node* t = last_peel;
2627 while (true) {
2628 wl.push(t);
2629 if (t == head_clone) break;
2630 t = idom(t);
2631 }
2632 while (wl.size() > 0) {
2633 Node* tt = wl.pop();
2634 if (tt == head) tty->print_cr("orig head");
2635 else if (tt == new_head_clone) tty->print_cr("new head");
2636 else if (tt == head_clone) tty->print_cr("clone head");
2637 tt->dump();
2638 }
2639 }
2640 #endif
2641 return true;
2642 }
2644 //------------------------------reorg_offsets----------------------------------
2645 // Reorganize offset computations to lower register pressure. Mostly
2646 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2647 // then alive with the post-incremented trip counter forcing an extra
2648 // register move)
2649 void PhaseIdealLoop::reorg_offsets( IdealLoopTree *loop ) {
2651 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2652 CountedLoopEndNode *cle = cl->loopexit();
2653 if( !cle ) return; // The occasional dead loop
2654 // Find loop exit control
2655 Node *exit = cle->proj_out(false);
2656 assert( exit->Opcode() == Op_IfFalse, "" );
2658 // Check for the special case of folks using the pre-incremented
2659 // trip-counter on the fall-out path (forces the pre-incremented
2660 // and post-incremented trip counter to be live at the same time).
2661 // Fix this by adjusting to use the post-increment trip counter.
2662 Node *phi = cl->phi();
2663 if( !phi ) return; // Dead infinite loop
2664 bool progress = true;
2665 while (progress) {
2666 progress = false;
2667 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
2668 Node* use = phi->fast_out(i); // User of trip-counter
2669 if (!has_ctrl(use)) continue;
2670 Node *u_ctrl = get_ctrl(use);
2671 if( use->is_Phi() ) {
2672 u_ctrl = NULL;
2673 for( uint j = 1; j < use->req(); j++ )
2674 if( use->in(j) == phi )
2675 u_ctrl = dom_lca( u_ctrl, use->in(0)->in(j) );
2676 }
2677 IdealLoopTree *u_loop = get_loop(u_ctrl);
2678 // Look for loop-invariant use
2679 if( u_loop == loop ) continue;
2680 if( loop->is_member( u_loop ) ) continue;
2681 // Check that use is live out the bottom. Assuming the trip-counter
2682 // update is right at the bottom, uses of of the loop middle are ok.
2683 if( dom_lca( exit, u_ctrl ) != exit ) continue;
2684 // protect against stride not being a constant
2685 if( !cle->stride_is_con() ) continue;
2686 // Hit! Refactor use to use the post-incremented tripcounter.
2687 // Compute a post-increment tripcounter.
2688 Node *opaq = new (C, 2) Opaque2Node( cle->incr() );
2689 register_new_node( opaq, u_ctrl );
2690 Node *neg_stride = _igvn.intcon(-cle->stride_con());
2691 set_ctrl(neg_stride, C->root());
2692 Node *post = new (C, 3) AddINode( opaq, neg_stride);
2693 register_new_node( post, u_ctrl );
2694 _igvn.hash_delete(use);
2695 _igvn._worklist.push(use);
2696 for( uint j = 1; j < use->req(); j++ )
2697 if( use->in(j) == phi )
2698 use->set_req(j, post);
2699 // Since DU info changed, rerun loop
2700 progress = true;
2701 break;
2702 }
2703 }
2705 }