1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)loopopts.cpp 1.222 08/11/24 12:23:09 JVM"
3 #endif
4 /*
5 * Copyright 1999-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 #include "incls/_precompiled.incl"
29 #include "incls/_loopopts.cpp.incl"
30
31 //=============================================================================
32 //------------------------------split_thru_phi---------------------------------
33 // Split Node 'n' through merge point if there is enough win.
34 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
35 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
36 // ConvI2L may have type information on it which is unsafe to push up
37 // so disable this for now
38 return NULL;
39 }
40 int wins = 0;
41 assert( !n->is_CFG(), "" );
42 assert( region->is_Region(), "" );
43
44 const Type* type = n->bottom_type();
45 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
46 Node *phi;
47 if( t_oop != NULL && t_oop->is_known_instance_field() ) {
48 int iid = t_oop->instance_id();
49 int index = C->get_alias_index(t_oop);
50 int offset = t_oop->offset();
51 phi = new (C,region->req()) PhiNode(region, type, NULL, iid, index, offset);
52 } else {
53 phi = new (C,region->req()) PhiNode(region, type);
54 }
55 uint old_unique = C->unique();
56 for( uint i = 1; i < region->req(); i++ ) {
57 Node *x;
58 Node* the_clone = NULL;
59 if( region->in(i) == C->top() ) {
60 x = C->top(); // Dead path? Use a dead data op
61 } else {
62 x = n->clone(); // Else clone up the data op
63 the_clone = x; // Remember for possible deletion.
64 // Alter data node to use pre-phi inputs
65 if( n->in(0) == region )
66 x->set_req( 0, region->in(i) );
67 for( uint j = 1; j < n->req(); j++ ) {
68 Node *in = n->in(j);
69 if( in->is_Phi() && in->in(0) == region )
70 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
71 }
72 }
73 // Check for a 'win' on some paths
74 const Type *t = x->Value(&_igvn);
75
76 bool singleton = t->singleton();
77
78 // A TOP singleton indicates that there are no possible values incoming
79 // along a particular edge. In most cases, this is OK, and the Phi will
80 // be eliminated later in an Ideal call. However, we can't allow this to
81 // happen if the singleton occurs on loop entry, as the elimination of
82 // the PhiNode may cause the resulting node to migrate back to a previous
83 // loop iteration.
84 if( singleton && t == Type::TOP ) {
85 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
86 // irreducible loop may not be indicated by an affirmative is_Loop());
87 // therefore, the only top we can split thru a phi is on a backedge of
88 // a loop.
89 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
90 }
91
92 if( singleton ) {
93 wins++;
94 x = ((PhaseGVN&)_igvn).makecon(t);
95 } else {
96 // We now call Identity to try to simplify the cloned node.
97 // Note that some Identity methods call phase->type(this).
98 // Make sure that the type array is big enough for
99 // our new node, even though we may throw the node away.
100 // (Note: This tweaking with igvn only works because x is a new node.)
101 _igvn.set_type(x, t);
102 // If x is a TypeNode, capture any more-precise type permanently into Node
103 // othewise it will be not updated during igvn->transform since
104 // igvn->type(x) is set to x->Value() already.
105 x->raise_bottom_type(t);
106 Node *y = x->Identity(&_igvn);
107 if( y != x ) {
108 wins++;
109 x = y;
110 } else {
111 y = _igvn.hash_find(x);
112 if( y ) {
113 wins++;
114 x = y;
115 } else {
116 // Else x is a new node we are keeping
117 // We do not need register_new_node_with_optimizer
118 // because set_type has already been called.
119 _igvn._worklist.push(x);
120 }
121 }
122 }
123 if (x != the_clone && the_clone != NULL)
124 _igvn.remove_dead_node(the_clone);
125 phi->set_req( i, x );
126 }
127 // Too few wins?
128 if( wins <= policy ) {
129 _igvn.remove_dead_node(phi);
130 return NULL;
131 }
132
133 // Record Phi
134 register_new_node( phi, region );
135
136 for( uint i2 = 1; i2 < phi->req(); i2++ ) {
137 Node *x = phi->in(i2);
138 // If we commoned up the cloned 'x' with another existing Node,
139 // the existing Node picks up a new use. We need to make the
140 // existing Node occur higher up so it dominates its uses.
141 Node *old_ctrl;
142 IdealLoopTree *old_loop;
143
144 // The occasional new node
145 if( x->_idx >= old_unique ) { // Found a new, unplaced node?
146 old_ctrl = x->is_Con() ? C->root() : NULL;
147 old_loop = NULL; // Not in any prior loop
148 } else {
149 old_ctrl = x->is_Con() ? C->root() : get_ctrl(x);
150 old_loop = get_loop(old_ctrl); // Get prior loop
151 }
152 // New late point must dominate new use
153 Node *new_ctrl = dom_lca( old_ctrl, region->in(i2) );
154 // Set new location
155 set_ctrl(x, new_ctrl);
156 IdealLoopTree *new_loop = get_loop( new_ctrl );
157 // If changing loop bodies, see if we need to collect into new body
158 if( old_loop != new_loop ) {
159 if( old_loop && !old_loop->_child )
160 old_loop->_body.yank(x);
161 if( !new_loop->_child )
162 new_loop->_body.push(x); // Collect body info
163 }
164 }
165
166 return phi;
167 }
168
169 //------------------------------dominated_by------------------------------------
170 // Replace the dominated test with an obvious true or false. Place it on the
171 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
172 // live path up to the dominating control.
173 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff ) {
174 #ifndef PRODUCT
175 if( VerifyLoopOptimizations && PrintOpto ) tty->print_cr("dominating test");
176 #endif
177
178
179 // prevdom is the dominating projection of the dominating test.
180 assert( iff->is_If(), "" );
181 assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
182 int pop = prevdom->Opcode();
183 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
184 // 'con' is set to true or false to kill the dominated test.
185 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
186 set_ctrl(con, C->root()); // Constant gets a new use
187 // Hack the dominated test
188 _igvn.hash_delete(iff);
189 iff->set_req(1, con);
190 _igvn._worklist.push(iff);
191
192 // If I dont have a reachable TRUE and FALSE path following the IfNode then
193 // I can assume this path reaches an infinite loop. In this case it's not
194 // important to optimize the data Nodes - either the whole compilation will
195 // be tossed or this path (and all data Nodes) will go dead.
196 if( iff->outcnt() != 2 ) return;
197
198 // Make control-dependent data Nodes on the live path (path that will remain
199 // once the dominated IF is removed) become control-dependent on the
200 // dominating projection.
201 Node* dp = ((IfNode*)iff)->proj_out(pop == Op_IfTrue);
202 IdealLoopTree *old_loop = get_loop(dp);
203
204 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
205 Node* cd = dp->fast_out(i); // Control-dependent node
206 if( cd->depends_only_on_test() ) {
207 assert( cd->in(0) == dp, "" );
208 _igvn.hash_delete( cd );
209 cd->set_req(0, prevdom);
210 set_early_ctrl( cd );
211 _igvn._worklist.push(cd);
212 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
213 if( old_loop != new_loop ) {
214 if( !old_loop->_child ) old_loop->_body.yank(cd);
215 if( !new_loop->_child ) new_loop->_body.push(cd);
216 }
217 --i;
218 --imax;
219 }
220 }
221 }
222
223 //------------------------------has_local_phi_input----------------------------
224 // Return TRUE if 'n' has Phi inputs from its local block and no other
225 // block-local inputs (all non-local-phi inputs come from earlier blocks)
226 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
227 Node *n_ctrl = get_ctrl(n);
228 // See if some inputs come from a Phi in this block, or from before
229 // this block.
230 uint i;
231 for( i = 1; i < n->req(); i++ ) {
232 Node *phi = n->in(i);
233 if( phi->is_Phi() && phi->in(0) == n_ctrl )
234 break;
235 }
236 if( i >= n->req() )
237 return NULL; // No Phi inputs; nowhere to clone thru
238
239 // Check for inputs created between 'n' and the Phi input. These
240 // must split as well; they have already been given the chance
241 // (courtesy of a post-order visit) and since they did not we must
242 // recover the 'cost' of splitting them by being very profitable
243 // when splitting 'n'. Since this is unlikely we simply give up.
244 for( i = 1; i < n->req(); i++ ) {
245 Node *m = n->in(i);
246 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
247 // We allow the special case of AddP's with no local inputs.
248 // This allows us to split-up address expressions.
249 if (m->is_AddP() &&
250 get_ctrl(m->in(2)) != n_ctrl &&
251 get_ctrl(m->in(3)) != n_ctrl) {
252 // Move the AddP up to dominating point
253 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
254 continue;
255 }
256 return NULL;
257 }
258 }
259
260 return n_ctrl;
261 }
262
263 //------------------------------remix_address_expressions----------------------
264 // Rework addressing expressions to get the most loop-invariant stuff
265 // moved out. We'd like to do all associative operators, but it's especially
266 // important (common) to do address expressions.
267 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
268 if (!has_ctrl(n)) return NULL;
269 Node *n_ctrl = get_ctrl(n);
270 IdealLoopTree *n_loop = get_loop(n_ctrl);
271
272 // See if 'n' mixes loop-varying and loop-invariant inputs and
273 // itself is loop-varying.
274
275 // Only interested in binary ops (and AddP)
276 if( n->req() < 3 || n->req() > 4 ) return NULL;
277
278 Node *n1_ctrl = get_ctrl(n->in( 1));
279 Node *n2_ctrl = get_ctrl(n->in( 2));
280 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
281 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
282 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
283 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
284
285 // Does one of my inputs spin in a tighter loop than self?
286 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
287 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
288 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
289 return NULL; // Leave well enough alone
290
291 // Is at least one of my inputs loop-invariant?
292 if( n1_loop == n_loop &&
293 n2_loop == n_loop &&
294 n3_loop == n_loop )
295 return NULL; // No loop-invariant inputs
296
297
298 int n_op = n->Opcode();
299
300 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
301 if( n_op == Op_LShiftI ) {
302 // Scale is loop invariant
303 Node *scale = n->in(2);
304 Node *scale_ctrl = get_ctrl(scale);
305 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
306 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
307 return NULL;
308 const TypeInt *scale_t = scale->bottom_type()->isa_int();
309 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
310 return NULL; // Dont bother with byte/short masking
311 // Add must vary with loop (else shift would be loop-invariant)
312 Node *add = n->in(1);
313 Node *add_ctrl = get_ctrl(add);
314 IdealLoopTree *add_loop = get_loop(add_ctrl);
315 //assert( n_loop == add_loop, "" );
316 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
317
318 // Convert I-V into I+ (0-V); same for V-I
319 if( add->Opcode() == Op_SubI &&
320 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
321 Node *zero = _igvn.intcon(0);
322 set_ctrl(zero, C->root());
323 Node *neg = new (C, 3) SubINode( _igvn.intcon(0), add->in(2) );
324 register_new_node( neg, get_ctrl(add->in(2) ) );
325 add = new (C, 3) AddINode( add->in(1), neg );
326 register_new_node( add, add_ctrl );
327 }
328 if( add->Opcode() != Op_AddI ) return NULL;
329 // See if one add input is loop invariant
330 Node *add_var = add->in(1);
331 Node *add_var_ctrl = get_ctrl(add_var);
332 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
333 Node *add_invar = add->in(2);
334 Node *add_invar_ctrl = get_ctrl(add_invar);
335 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
336 if( add_var_loop == n_loop ) {
337 } else if( add_invar_loop == n_loop ) {
338 // Swap to find the invariant part
339 add_invar = add_var;
340 add_invar_ctrl = add_var_ctrl;
341 add_invar_loop = add_var_loop;
342 add_var = add->in(2);
343 Node *add_var_ctrl = get_ctrl(add_var);
344 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
345 } else // Else neither input is loop invariant
346 return NULL;
347 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
348 return NULL; // No invariant part of the add?
349
350 // Yes! Reshape address expression!
351 Node *inv_scale = new (C, 3) LShiftINode( add_invar, scale );
352 register_new_node( inv_scale, add_invar_ctrl );
353 Node *var_scale = new (C, 3) LShiftINode( add_var, scale );
354 register_new_node( var_scale, n_ctrl );
355 Node *var_add = new (C, 3) AddINode( var_scale, inv_scale );
356 register_new_node( var_add, n_ctrl );
357 _igvn.hash_delete( n );
358 _igvn.subsume_node( n, var_add );
359 return var_add;
360 }
361
362 // Replace (I+V) with (V+I)
363 if( n_op == Op_AddI ||
364 n_op == Op_AddL ||
365 n_op == Op_AddF ||
366 n_op == Op_AddD ||
367 n_op == Op_MulI ||
368 n_op == Op_MulL ||
369 n_op == Op_MulF ||
370 n_op == Op_MulD ) {
371 if( n2_loop == n_loop ) {
372 assert( n1_loop != n_loop, "" );
373 n->swap_edges(1, 2);
374 }
375 }
376
377 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
378 // but not if I2 is a constant.
379 if( n_op == Op_AddP ) {
380 if( n2_loop == n_loop && n3_loop != n_loop ) {
381 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
382 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
383 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
384 IdealLoopTree *n22loop = get_loop( n22_ctrl );
385 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
386 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
387 n23_loop == n_loop ) {
388 Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
389 // Stuff new AddP in the loop preheader
390 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
391 Node *add2 = new (C, 4) AddPNode( n->in(1), add1, n->in(2)->in(3) );
392 register_new_node( add2, n_ctrl );
393 _igvn.hash_delete( n );
394 _igvn.subsume_node( n, add2 );
395 return add2;
396 }
397 }
398 }
399
400 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
401 if( n2_loop != n_loop && n3_loop == n_loop ) {
402 if( n->in(3)->Opcode() == Op_AddI ) {
403 Node *V = n->in(3)->in(1);
404 Node *I = n->in(3)->in(2);
405 if( is_member(n_loop,get_ctrl(V)) ) {
406 } else {
407 Node *tmp = V; V = I; I = tmp;
408 }
409 if( !is_member(n_loop,get_ctrl(I)) ) {
410 Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2), I );
411 // Stuff new AddP in the loop preheader
412 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
413 Node *add2 = new (C, 4) AddPNode( n->in(1), add1, V );
414 register_new_node( add2, n_ctrl );
415 _igvn.hash_delete( n );
416 _igvn.subsume_node( n, add2 );
417 return add2;
418 }
419 }
420 }
421 }
422
423 return NULL;
424 }
425
426 //------------------------------conditional_move-------------------------------
427 // Attempt to replace a Phi with a conditional move. We have some pretty
428 // strict profitability requirements. All Phis at the merge point must
429 // be converted, so we can remove the control flow. We need to limit the
430 // number of c-moves to a small handful. All code that was in the side-arms
431 // of the CFG diamond is now speculatively executed. This code has to be
432 // "cheap enough". We are pretty much limited to CFG diamonds that merge
433 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
434 Node *PhaseIdealLoop::conditional_move( Node *region ) {
435
436 assert( region->is_Region(), "sanity check" );
437 if( region->req() != 3 ) return NULL;
438
439 // Check for CFG diamond
440 Node *lp = region->in(1);
441 Node *rp = region->in(2);
442 if( !lp || !rp ) return NULL;
443 Node *lp_c = lp->in(0);
444 if( lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If() ) return NULL;
445 IfNode *iff = lp_c->as_If();
446
447 // Check for highly predictable branch. No point in CMOV'ing if
448 // we are going to predict accurately all the time.
449 // %%% This hides patterns produced by utility methods like Math.min.
450 if( iff->_prob < PROB_UNLIKELY_MAG(3) ||
451 iff->_prob > PROB_LIKELY_MAG(3) )
452 return NULL;
453
454 // Check for ops pinned in an arm of the diamond.
455 // Can't remove the control flow in this case
456 if( lp->outcnt() > 1 ) return NULL;
457 if( rp->outcnt() > 1 ) return NULL;
458
459 // Check profitability
460 int cost = 0;
461 int phis = 0;
462 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
463 Node *out = region->fast_out(i);
464 if( !out->is_Phi() ) continue; // Ignore other control edges, etc
465 phis++;
466 PhiNode* phi = out->as_Phi();
467 switch (phi->type()->basic_type()) {
468 case T_LONG:
469 cost++; // Probably encodes as 2 CMOV's
470 case T_INT: // These all CMOV fine
471 case T_FLOAT:
472 case T_DOUBLE:
473 case T_ADDRESS: // (RawPtr)
474 cost++;
475 break;
476 case T_NARROWOOP: // Fall through
477 case T_OBJECT: { // Base oops are OK, but not derived oops
478 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
479 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
480 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
481 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
482 // have a Phi for the base here that we convert to a CMOVE all is well
483 // and good. But if the base is dead, we'll not make a CMOVE. Later
484 // the allocator will have to produce a base by creating a CMOVE of the
485 // relevant bases. This puts the allocator in the business of
486 // manufacturing expensive instructions, generally a bad plan.
487 // Just Say No to Conditionally-Moved Derived Pointers.
488 if( tp && tp->offset() != 0 )
489 return NULL;
490 cost++;
491 break;
492 }
493 default:
494 return NULL; // In particular, can't do memory or I/O
495 }
496 // Add in cost any speculative ops
497 for( uint j = 1; j < region->req(); j++ ) {
498 Node *proj = region->in(j);
499 Node *inp = phi->in(j);
500 if (get_ctrl(inp) == proj) { // Found local op
501 cost++;
502 // Check for a chain of dependent ops; these will all become
503 // speculative in a CMOV.
504 for( uint k = 1; k < inp->req(); k++ )
505 if (get_ctrl(inp->in(k)) == proj)
506 return NULL; // Too much speculative goo
507 }
508 }
509 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
510 // This will likely Split-If, a higher-payoff operation.
511 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
512 Node* use = phi->fast_out(k);
513 if( use->is_Cmp() || use->is_DecodeN() || use->is_EncodeP() )
514 return NULL;
515 }
516 }
517 if( cost >= ConditionalMoveLimit ) return NULL; // Too much goo
518 Node* bol = iff->in(1);
519 assert( bol->Opcode() == Op_Bool, "" );
520 int cmp_op = bol->in(1)->Opcode();
521 // It is expensive to generate flags from a float compare.
522 // Avoid duplicated float compare.
523 if( phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
524
525 // --------------
526 // Now replace all Phis with CMOV's
527 Node *cmov_ctrl = iff->in(0);
528 uint flip = (lp->Opcode() == Op_IfTrue);
529 while( 1 ) {
530 PhiNode* phi = NULL;
531 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
532 Node *out = region->fast_out(i);
533 if (out->is_Phi()) {
534 phi = out->as_Phi();
535 break;
536 }
537 }
538 if (phi == NULL) break;
539 #ifndef PRODUCT
540 if( PrintOpto && VerifyLoopOptimizations ) tty->print_cr("CMOV");
541 #endif
542 // Move speculative ops
543 for( uint j = 1; j < region->req(); j++ ) {
544 Node *proj = region->in(j);
545 Node *inp = phi->in(j);
546 if (get_ctrl(inp) == proj) { // Found local op
547 #ifndef PRODUCT
548 if( PrintOpto && VerifyLoopOptimizations ) {
549 tty->print(" speculate: ");
550 inp->dump();
551 }
552 #endif
553 set_ctrl(inp, cmov_ctrl);
554 }
555 }
556 Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) );
557 register_new_node( cmov, cmov_ctrl );
558 _igvn.hash_delete(phi);
559 _igvn.subsume_node( phi, cmov );
560 #ifndef PRODUCT
561 if( VerifyLoopOptimizations ) verify();
562 #endif
563 }
564
565 // The useless CFG diamond will fold up later; see the optimization in
566 // RegionNode::Ideal.
567 _igvn._worklist.push(region);
568
569 return iff->in(1);
570 }
571
572 //------------------------------split_if_with_blocks_pre-----------------------
573 // Do the real work in a non-recursive function. Data nodes want to be
574 // cloned in the pre-order so they can feed each other nicely.
575 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
576 // Cloning these guys is unlikely to win
577 int n_op = n->Opcode();
578 if( n_op == Op_MergeMem ) return n;
579 if( n->is_Proj() ) return n;
580 // Do not clone-up CmpFXXX variations, as these are always
581 // followed by a CmpI
582 if( n->is_Cmp() ) return n;
583 // Attempt to use a conditional move instead of a phi/branch
584 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
585 Node *cmov = conditional_move( n );
586 if( cmov ) return cmov;
587 }
588 if( n->is_CFG() || n->is_LoadStore() )
589 return n;
590 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
591 n_op == Op_Opaque2 ) {
592 if( !C->major_progress() ) // If chance of no more loop opts...
593 _igvn._worklist.push(n); // maybe we'll remove them
594 return n;
595 }
596
597 if( n->is_Con() ) return n; // No cloning for Con nodes
598
599 Node *n_ctrl = get_ctrl(n);
600 if( !n_ctrl ) return n; // Dead node
601
602 // Attempt to remix address expressions for loop invariants
603 Node *m = remix_address_expressions( n );
604 if( m ) return m;
605
606 // Determine if the Node has inputs from some local Phi.
607 // Returns the block to clone thru.
608 Node *n_blk = has_local_phi_input( n );
609 if( !n_blk ) return n;
610 // Do not clone the trip counter through on a CountedLoop
611 // (messes up the canonical shape).
612 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
613
614 // Check for having no control input; not pinned. Allow
615 // dominating control.
616 if( n->in(0) ) {
617 Node *dom = idom(n_blk);
618 if( dom_lca( n->in(0), dom ) != n->in(0) )
619 return n;
620 }
621 // Policy: when is it profitable. You must get more wins than
622 // policy before it is considered profitable. Policy is usually 0,
623 // so 1 win is considered profitable. Big merges will require big
624 // cloning, so get a larger policy.
625 int policy = n_blk->req() >> 2;
626
627 // If the loop is a candidate for range check elimination,
628 // delay splitting through it's phi until a later loop optimization
629 if (n_blk->is_CountedLoop()) {
630 IdealLoopTree *lp = get_loop(n_blk);
631 if (lp && lp->_rce_candidate) {
632 return n;
633 }
634 }
635
636 // Use same limit as split_if_with_blocks_post
637 if( C->unique() > 35000 ) return n; // Method too big
638
639 // Split 'n' through the merge point if it is profitable
640 Node *phi = split_thru_phi( n, n_blk, policy );
641 if( !phi ) return n;
642
643 // Found a Phi to split thru!
644 // Replace 'n' with the new phi
645 _igvn.hash_delete(n);
646 _igvn.subsume_node( n, phi );
647 // Moved a load around the loop, 'en-registering' something.
648 if( n_blk->Opcode() == Op_Loop && n->is_Load() &&
649 !phi->in(LoopNode::LoopBackControl)->is_Load() )
650 C->set_major_progress();
651
652 return phi;
653 }
654
655 static bool merge_point_too_heavy(Compile* C, Node* region) {
656 // Bail out if the region and its phis have too many users.
657 int weight = 0;
658 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
659 weight += region->fast_out(i)->outcnt();
660 }
661 int nodes_left = MaxNodeLimit - C->unique();
662 if (weight * 8 > nodes_left) {
663 #ifndef PRODUCT
664 if (PrintOpto)
665 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
666 #endif
667 return true;
668 } else {
669 return false;
670 }
671 }
672
673 #ifdef _LP64
674 static bool merge_point_safe(Node* region) {
675 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
676 // having a PhiNode input. This sidesteps the dangerous case where the split
677 // ConvI2LNode may become TOP if the input Value() does not
678 // overlap the ConvI2L range, leaving a node which may not dominate its
679 // uses.
680 // A better fix for this problem can be found in the BugTraq entry, but
681 // expediency for Mantis demands this hack.
682 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
683 Node* n = region->fast_out(i);
684 if (n->is_Phi()) {
685 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
686 Node* m = n->fast_out(j);
687 if (m->Opcode() == Op_ConvI2L) {
688 return false;
689 }
690 }
691 }
692 }
693 return true;
694 }
695 #endif
696
697
698 //------------------------------place_near_use---------------------------------
699 // Place some computation next to use but not inside inner loops.
700 // For inner loop uses move it to the preheader area.
701 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
702 IdealLoopTree *u_loop = get_loop( useblock );
703 return (u_loop->_irreducible || u_loop->_child)
704 ? useblock
705 : u_loop->_head->in(LoopNode::EntryControl);
706 }
707
708
709 //------------------------------split_if_with_blocks_post----------------------
710 // Do the real work in a non-recursive function. CFG hackery wants to be
711 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
712 // info.
713 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
714
715 // Cloning Cmp through Phi's involves the split-if transform.
716 // FastLock is not used by an If
717 if( n->is_Cmp() && !n->is_FastLock() ) {
718 if( C->unique() > 35000 ) return; // Method too big
719
720 // Do not do 'split-if' if irreducible loops are present.
721 if( _has_irreducible_loops )
722 return;
723
724 Node *n_ctrl = get_ctrl(n);
725 // Determine if the Node has inputs from some local Phi.
726 // Returns the block to clone thru.
727 Node *n_blk = has_local_phi_input( n );
728 if( n_blk != n_ctrl ) return;
729
730 if( merge_point_too_heavy(C, n_ctrl) )
731 return;
732
733 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
734 Node *bol = n->unique_out();
735 assert( bol->is_Bool(), "expect a bool here" );
736 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
737 Node *iff = bol->unique_out();
738
739 // Check some safety conditions
740 if( iff->is_If() ) { // Classic split-if?
741 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
742 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
743 if( get_ctrl(iff->in(2)) == n_ctrl ||
744 get_ctrl(iff->in(3)) == n_ctrl )
745 return; // Inputs not yet split-up
746 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
747 return; // Loop-invar test gates loop-varying CMOVE
748 }
749 } else {
750 return; // some other kind of node, such as an Allocate
751 }
752
753 // Do not do 'split-if' if some paths are dead. First do dead code
754 // elimination and then see if its still profitable.
755 for( uint i = 1; i < n_ctrl->req(); i++ )
756 if( n_ctrl->in(i) == C->top() )
757 return;
758
759 // When is split-if profitable? Every 'win' on means some control flow
760 // goes dead, so it's almost always a win.
761 int policy = 0;
762 // If trying to do a 'Split-If' at the loop head, it is only
763 // profitable if the cmp folds up on BOTH paths. Otherwise we
764 // risk peeling a loop forever.
765
766 // CNC - Disabled for now. Requires careful handling of loop
767 // body selection for the cloned code. Also, make sure we check
768 // for any input path not being in the same loop as n_ctrl. For
769 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
770 // because the alternative loop entry points won't be converted
771 // into LoopNodes.
772 IdealLoopTree *n_loop = get_loop(n_ctrl);
773 for( uint j = 1; j < n_ctrl->req(); j++ )
774 if( get_loop(n_ctrl->in(j)) != n_loop )
775 return;
776
777 #ifdef _LP64
778 // Check for safety of the merge point.
779 if( !merge_point_safe(n_ctrl) ) {
780 return;
781 }
782 #endif
783
784 // Split compare 'n' through the merge point if it is profitable
785 Node *phi = split_thru_phi( n, n_ctrl, policy );
786 if( !phi ) return;
787
788 // Found a Phi to split thru!
789 // Replace 'n' with the new phi
790 _igvn.hash_delete(n);
791 _igvn.subsume_node( n, phi );
792
793 // Now split the bool up thru the phi
794 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
795 _igvn.hash_delete(bol);
796 _igvn.subsume_node( bol, bolphi );
797 assert( iff->in(1) == bolphi, "" );
798 if( bolphi->Value(&_igvn)->singleton() )
799 return;
800
801 // Conditional-move? Must split up now
802 if( !iff->is_If() ) {
803 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
804 _igvn.hash_delete(iff);
805 _igvn.subsume_node( iff, cmovphi );
806 return;
807 }
808
809 // Now split the IF
810 do_split_if( iff );
811 return;
812 }
813
814 // Check for an IF ready to split; one that has its
815 // condition codes input coming from a Phi at the block start.
816 int n_op = n->Opcode();
817
818 // Check for an IF being dominated by another IF same test
819 if( n_op == Op_If ) {
820 Node *bol = n->in(1);
821 uint max = bol->outcnt();
822 // Check for same test used more than once?
823 if( n_op == Op_If && max > 1 && bol->is_Bool() ) {
824 // Search up IDOMs to see if this IF is dominated.
825 Node *cutoff = get_ctrl(bol);
826
827 // Now search up IDOMs till cutoff, looking for a dominating test
828 Node *prevdom = n;
829 Node *dom = idom(prevdom);
830 while( dom != cutoff ) {
831 if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) {
832 // Replace the dominated test with an obvious true or false.
833 // Place it on the IGVN worklist for later cleanup.
834 C->set_major_progress();
835 dominated_by( prevdom, n );
836 #ifndef PRODUCT
837 if( VerifyLoopOptimizations ) verify();
838 #endif
839 return;
840 }
841 prevdom = dom;
842 dom = idom(prevdom);
843 }
844 }
845 }
846
847 // See if a shared loop-varying computation has no loop-varying uses.
848 // Happens if something is only used for JVM state in uncommon trap exits,
849 // like various versions of induction variable+offset. Clone the
850 // computation per usage to allow it to sink out of the loop.
851 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
852 Node *n_ctrl = get_ctrl(n);
853 IdealLoopTree *n_loop = get_loop(n_ctrl);
854 if( n_loop != _ltree_root ) {
855 DUIterator_Fast imax, i = n->fast_outs(imax);
856 for (; i < imax; i++) {
857 Node* u = n->fast_out(i);
858 if( !has_ctrl(u) ) break; // Found control user
859 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
860 if( u_loop == n_loop ) break; // Found loop-varying use
861 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
862 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
863 }
864 bool did_break = (i < imax); // Did we break out of the previous loop?
865 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
866 Node *late_load_ctrl;
867 if (n->is_Load()) {
868 // If n is a load, get and save the result from get_late_ctrl(),
869 // to be later used in calculating the control for n's clones.
870 clear_dom_lca_tags();
871 late_load_ctrl = get_late_ctrl(n, n_ctrl);
872 }
873 // If n is a load, and the late control is the same as the current
874 // control, then the cloning of n is a pointless exercise, because
875 // GVN will ensure that we end up where we started.
876 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
877 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
878 Node *u = n->last_out(j); // Clone private computation per use
879 _igvn.hash_delete(u);
880 _igvn._worklist.push(u);
881 Node *x = n->clone(); // Clone computation
882 Node *x_ctrl = NULL;
883 if( u->is_Phi() ) {
884 // Replace all uses of normal nodes. Replace Phi uses
885 // individually, so the seperate Nodes can sink down
886 // different paths.
887 uint k = 1;
888 while( u->in(k) != n ) k++;
889 u->set_req( k, x );
890 // x goes next to Phi input path
891 x_ctrl = u->in(0)->in(k);
892 --j;
893 } else { // Normal use
894 // Replace all uses
895 for( uint k = 0; k < u->req(); k++ ) {
896 if( u->in(k) == n ) {
897 u->set_req( k, x );
898 --j;
899 }
900 }
901 x_ctrl = get_ctrl(u);
902 }
903
904 // Find control for 'x' next to use but not inside inner loops.
905 // For inner loop uses get the preheader area.
906 x_ctrl = place_near_use(x_ctrl);
907
908 if (n->is_Load()) {
909 // For loads, add a control edge to a CFG node outside of the loop
910 // to force them to not combine and return back inside the loop
911 // during GVN optimization (4641526).
912 //
913 // Because we are setting the actual control input, factor in
914 // the result from get_late_ctrl() so we respect any
915 // anti-dependences. (6233005).
916 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
917
918 // Don't allow the control input to be a CFG splitting node.
919 // Such nodes should only have ProjNodes as outs, e.g. IfNode
920 // should only have IfTrueNode and IfFalseNode (4985384).
921 x_ctrl = find_non_split_ctrl(x_ctrl);
922 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
923
924 x->set_req(0, x_ctrl);
925 }
926 register_new_node(x, x_ctrl);
927
928 // Some institutional knowledge is needed here: 'x' is
929 // yanked because if the optimizer runs GVN on it all the
930 // cloned x's will common up and undo this optimization and
931 // be forced back in the loop. This is annoying because it
932 // makes +VerifyOpto report false-positives on progress. I
933 // tried setting control edges on the x's to force them to
934 // not combine, but the matching gets worried when it tries
935 // to fold a StoreP and an AddP together (as part of an
936 // address expression) and the AddP and StoreP have
937 // different controls.
938 if( !x->is_Load() && !x->is_DecodeN() ) _igvn._worklist.yank(x);
939 }
940 _igvn.remove_dead_node(n);
941 }
942 }
943 }
944 }
945
946 // Check for Opaque2's who's loop has disappeared - who's input is in the
947 // same loop nest as their output. Remove 'em, they are no longer useful.
948 if( n_op == Op_Opaque2 &&
949 n->in(1) != NULL &&
950 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
951 _igvn.add_users_to_worklist(n);
952 _igvn.hash_delete(n);
953 _igvn.subsume_node( n, n->in(1) );
954 }
955 }
956
957 //------------------------------split_if_with_blocks---------------------------
958 // Check for aggressive application of 'split-if' optimization,
959 // using basic block level info.
960 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
961 Node *n = C->root();
962 visited.set(n->_idx); // first, mark node as visited
963 // Do pre-visit work for root
964 n = split_if_with_blocks_pre( n );
965 uint cnt = n->outcnt();
966 uint i = 0;
967 while (true) {
968 // Visit all children
969 if (i < cnt) {
970 Node* use = n->raw_out(i);
971 ++i;
972 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
973 // Now do pre-visit work for this use
974 use = split_if_with_blocks_pre( use );
975 nstack.push(n, i); // Save parent and next use's index.
976 n = use; // Process all children of current use.
977 cnt = use->outcnt();
978 i = 0;
979 }
980 }
981 else {
982 // All of n's children have been processed, complete post-processing.
983 if (cnt != 0 && !n->is_Con()) {
984 assert(has_node(n), "no dead nodes");
985 split_if_with_blocks_post( n );
986 }
987 if (nstack.is_empty()) {
988 // Finished all nodes on stack.
989 break;
990 }
991 // Get saved parent node and next use's index. Visit the rest of uses.
992 n = nstack.node();
993 cnt = n->outcnt();
994 i = nstack.index();
995 nstack.pop();
996 }
997 }
998 }
999
1000
1001 //=============================================================================
1002 //
1003 // C L O N E A L O O P B O D Y
1004 //
1005
1006 //------------------------------clone_iff--------------------------------------
1007 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1008 // "Nearly" because all Nodes have been cloned from the original in the loop,
1009 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1010 // through the Phi recursively, and return a Bool.
1011 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1012
1013 // Convert this Phi into a Phi merging Bools
1014 uint i;
1015 for( i = 1; i < phi->req(); i++ ) {
1016 Node *b = phi->in(i);
1017 if( b->is_Phi() ) {
1018 _igvn.hash_delete(phi);
1019 _igvn._worklist.push(phi);
1020 phi->set_req(i, clone_iff( b->as_Phi(), loop ));
1021 } else {
1022 assert( b->is_Bool(), "" );
1023 }
1024 }
1025
1026 Node *sample_bool = phi->in(1);
1027 Node *sample_cmp = sample_bool->in(1);
1028
1029 // Make Phis to merge the Cmp's inputs.
1030 int size = phi->in(0)->req();
1031 PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1032 PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1033 for( i = 1; i < phi->req(); i++ ) {
1034 Node *n1 = phi->in(i)->in(1)->in(1);
1035 Node *n2 = phi->in(i)->in(1)->in(2);
1036 phi1->set_req( i, n1 );
1037 phi2->set_req( i, n2 );
1038 phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
1039 phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
1040 }
1041 // See if these Phis have been made before.
1042 // Register with optimizer
1043 Node *hit1 = _igvn.hash_find_insert(phi1);
1044 if( hit1 ) { // Hit, toss just made Phi
1045 _igvn.remove_dead_node(phi1); // Remove new phi
1046 assert( hit1->is_Phi(), "" );
1047 phi1 = (PhiNode*)hit1; // Use existing phi
1048 } else { // Miss
1049 _igvn.register_new_node_with_optimizer(phi1);
1050 }
1051 Node *hit2 = _igvn.hash_find_insert(phi2);
1052 if( hit2 ) { // Hit, toss just made Phi
1053 _igvn.remove_dead_node(phi2); // Remove new phi
1054 assert( hit2->is_Phi(), "" );
1055 phi2 = (PhiNode*)hit2; // Use existing phi
1056 } else { // Miss
1057 _igvn.register_new_node_with_optimizer(phi2);
1058 }
1059 // Register Phis with loop/block info
1060 set_ctrl(phi1, phi->in(0));
1061 set_ctrl(phi2, phi->in(0));
1062 // Make a new Cmp
1063 Node *cmp = sample_cmp->clone();
1064 cmp->set_req( 1, phi1 );
1065 cmp->set_req( 2, phi2 );
1066 _igvn.register_new_node_with_optimizer(cmp);
1067 set_ctrl(cmp, phi->in(0));
1068
1069 // Make a new Bool
1070 Node *b = sample_bool->clone();
1071 b->set_req(1,cmp);
1072 _igvn.register_new_node_with_optimizer(b);
1073 set_ctrl(b, phi->in(0));
1074
1075 assert( b->is_Bool(), "" );
1076 return (BoolNode*)b;
1077 }
1078
1079 //------------------------------clone_bool-------------------------------------
1080 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1081 // "Nearly" because all Nodes have been cloned from the original in the loop,
1082 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1083 // through the Phi recursively, and return a Bool.
1084 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1085 uint i;
1086 // Convert this Phi into a Phi merging Bools
1087 for( i = 1; i < phi->req(); i++ ) {
1088 Node *b = phi->in(i);
1089 if( b->is_Phi() ) {
1090 _igvn.hash_delete(phi);
1091 _igvn._worklist.push(phi);
1092 phi->set_req(i, clone_bool( b->as_Phi(), loop ));
1093 } else {
1094 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1095 }
1096 }
1097
1098 Node *sample_cmp = phi->in(1);
1099
1100 // Make Phis to merge the Cmp's inputs.
1101 int size = phi->in(0)->req();
1102 PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1103 PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1104 for( uint j = 1; j < phi->req(); j++ ) {
1105 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1106 Node *n1, *n2;
1107 if( cmp_top->is_Cmp() ) {
1108 n1 = cmp_top->in(1);
1109 n2 = cmp_top->in(2);
1110 } else {
1111 n1 = n2 = cmp_top;
1112 }
1113 phi1->set_req( j, n1 );
1114 phi2->set_req( j, n2 );
1115 phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
1116 phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
1117 }
1118
1119 // See if these Phis have been made before.
1120 // Register with optimizer
1121 Node *hit1 = _igvn.hash_find_insert(phi1);
1122 if( hit1 ) { // Hit, toss just made Phi
1123 _igvn.remove_dead_node(phi1); // Remove new phi
1124 assert( hit1->is_Phi(), "" );
1125 phi1 = (PhiNode*)hit1; // Use existing phi
1126 } else { // Miss
1127 _igvn.register_new_node_with_optimizer(phi1);
1128 }
1129 Node *hit2 = _igvn.hash_find_insert(phi2);
1130 if( hit2 ) { // Hit, toss just made Phi
1131 _igvn.remove_dead_node(phi2); // Remove new phi
1132 assert( hit2->is_Phi(), "" );
1133 phi2 = (PhiNode*)hit2; // Use existing phi
1134 } else { // Miss
1135 _igvn.register_new_node_with_optimizer(phi2);
1136 }
1137 // Register Phis with loop/block info
1138 set_ctrl(phi1, phi->in(0));
1139 set_ctrl(phi2, phi->in(0));
1140 // Make a new Cmp
1141 Node *cmp = sample_cmp->clone();
1142 cmp->set_req( 1, phi1 );
1143 cmp->set_req( 2, phi2 );
1144 _igvn.register_new_node_with_optimizer(cmp);
1145 set_ctrl(cmp, phi->in(0));
1146
1147 assert( cmp->is_Cmp(), "" );
1148 return (CmpNode*)cmp;
1149 }
1150
1151 //------------------------------sink_use---------------------------------------
1152 // If 'use' was in the loop-exit block, it now needs to be sunk
1153 // below the post-loop merge point.
1154 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1155 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1156 set_ctrl(use, post_loop);
1157 for (DUIterator j = use->outs(); use->has_out(j); j++)
1158 sink_use(use->out(j), post_loop);
1159 }
1160 }
1161
1162 //------------------------------clone_loop-------------------------------------
1163 //
1164 // C L O N E A L O O P B O D Y
1165 //
1166 // This is the basic building block of the loop optimizations. It clones an
1167 // entire loop body. It makes an old_new loop body mapping; with this mapping
1168 // you can find the new-loop equivalent to an old-loop node. All new-loop
1169 // nodes are exactly equal to their old-loop counterparts, all edges are the
1170 // same. All exits from the old-loop now have a RegionNode that merges the
1171 // equivalent new-loop path. This is true even for the normal "loop-exit"
1172 // condition. All uses of loop-invariant old-loop values now come from (one
1173 // or more) Phis that merge their new-loop equivalents.
1174 //
1175 // This operation leaves the graph in an illegal state: there are two valid
1176 // control edges coming from the loop pre-header to both loop bodies. I'll
1177 // definitely have to hack the graph after running this transform.
1178 //
1179 // From this building block I will further edit edges to perform loop peeling
1180 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1181 //
1182 // Parameter side_by_size_idom:
1183 // When side_by_size_idom is NULL, the dominator tree is constructed for
1184 // the clone loop to dominate the original. Used in construction of
1185 // pre-main-post loop sequence.
1186 // When nonnull, the clone and original are side-by-side, both are
1187 // dominated by the side_by_side_idom node. Used in construction of
1188 // unswitched loops.
1189 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1190 Node* side_by_side_idom) {
1191
1192 // Step 1: Clone the loop body. Make the old->new mapping.
1193 uint i;
1194 for( i = 0; i < loop->_body.size(); i++ ) {
1195 Node *old = loop->_body.at(i);
1196 Node *nnn = old->clone();
1197 old_new.map( old->_idx, nnn );
1198 _igvn.register_new_node_with_optimizer(nnn);
1199 }
1200
1201
1202 // Step 2: Fix the edges in the new body. If the old input is outside the
1203 // loop use it. If the old input is INside the loop, use the corresponding
1204 // new node instead.
1205 for( i = 0; i < loop->_body.size(); i++ ) {
1206 Node *old = loop->_body.at(i);
1207 Node *nnn = old_new[old->_idx];
1208 // Fix CFG/Loop controlling the new node
1209 if (has_ctrl(old)) {
1210 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1211 } else {
1212 set_loop(nnn, loop->_parent);
1213 if (old->outcnt() > 0) {
1214 set_idom( nnn, old_new[idom(old)->_idx], dd );
1215 }
1216 }
1217 // Correct edges to the new node
1218 for( uint j = 0; j < nnn->req(); j++ ) {
1219 Node *n = nnn->in(j);
1220 if( n ) {
1221 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1222 if( loop->is_member( old_in_loop ) )
1223 nnn->set_req(j, old_new[n->_idx]);
1224 }
1225 }
1226 _igvn.hash_find_insert(nnn);
1227 }
1228 Node *newhead = old_new[loop->_head->_idx];
1229 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1230
1231
1232 // Step 3: Now fix control uses. Loop varying control uses have already
1233 // been fixed up (as part of all input edges in Step 2). Loop invariant
1234 // control uses must be either an IfFalse or an IfTrue. Make a merge
1235 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1236 // refer to this.
1237 ResourceArea *area = Thread::current()->resource_area();
1238 Node_List worklist(area);
1239 uint new_counter = C->unique();
1240 for( i = 0; i < loop->_body.size(); i++ ) {
1241 Node* old = loop->_body.at(i);
1242 if( !old->is_CFG() ) continue;
1243 Node* nnn = old_new[old->_idx];
1244
1245 // Copy uses to a worklist, so I can munge the def-use info
1246 // with impunity.
1247 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1248 worklist.push(old->fast_out(j));
1249
1250 while( worklist.size() ) { // Visit all uses
1251 Node *use = worklist.pop();
1252 if (!has_node(use)) continue; // Ignore dead nodes
1253 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1254 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1255 // Both OLD and USE are CFG nodes here.
1256 assert( use->is_Proj(), "" );
1257
1258 // Clone the loop exit control projection
1259 Node *newuse = use->clone();
1260 newuse->set_req(0,nnn);
1261 _igvn.register_new_node_with_optimizer(newuse);
1262 set_loop(newuse, use_loop);
1263 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1264
1265 // We need a Region to merge the exit from the peeled body and the
1266 // exit from the old loop body.
1267 RegionNode *r = new (C, 3) RegionNode(3);
1268 // Map the old use to the new merge point
1269 old_new.map( use->_idx, r );
1270 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1271 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1272
1273 // The original user of 'use' uses 'r' instead.
1274 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1275 Node* useuse = use->last_out(l);
1276 _igvn.hash_delete(useuse);
1277 _igvn._worklist.push(useuse);
1278 uint uses_found = 0;
1279 if( useuse->in(0) == use ) {
1280 useuse->set_req(0, r);
1281 uses_found++;
1282 if( useuse->is_CFG() ) {
1283 assert( dom_depth(useuse) > dd_r, "" );
1284 set_idom(useuse, r, dom_depth(useuse));
1285 }
1286 }
1287 for( uint k = 1; k < useuse->req(); k++ ) {
1288 if( useuse->in(k) == use ) {
1289 useuse->set_req(k, r);
1290 uses_found++;
1291 }
1292 }
1293 l -= uses_found; // we deleted 1 or more copies of this edge
1294 }
1295
1296 // Now finish up 'r'
1297 r->set_req( 1, newuse );
1298 r->set_req( 2, use );
1299 _igvn.register_new_node_with_optimizer(r);
1300 set_loop(r, use_loop);
1301 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1302 } // End of if a loop-exit test
1303 }
1304 }
1305
1306 // Step 4: If loop-invariant use is not control, it must be dominated by a
1307 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1308 // there if needed. Make a Phi there merging old and new used values.
1309 Node_List *split_if_set = NULL;
1310 Node_List *split_bool_set = NULL;
1311 Node_List *split_cex_set = NULL;
1312 for( i = 0; i < loop->_body.size(); i++ ) {
1313 Node* old = loop->_body.at(i);
1314 Node* nnn = old_new[old->_idx];
1315 // Copy uses to a worklist, so I can munge the def-use info
1316 // with impunity.
1317 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1318 worklist.push(old->fast_out(j));
1319
1320 while( worklist.size() ) {
1321 Node *use = worklist.pop();
1322 if (!has_node(use)) continue; // Ignore dead nodes
1323 if (use->in(0) == C->top()) continue;
1324 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1325 // Check for data-use outside of loop - at least one of OLD or USE
1326 // must not be a CFG node.
1327 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1328
1329 // If the Data use is an IF, that means we have an IF outside of the
1330 // loop that is switching on a condition that is set inside of the
1331 // loop. Happens if people set a loop-exit flag; then test the flag
1332 // in the loop to break the loop, then test is again outside of the
1333 // loop to determine which way the loop exited.
1334 if( use->is_If() || use->is_CMove() ) {
1335 // Since this code is highly unlikely, we lazily build the worklist
1336 // of such Nodes to go split.
1337 if( !split_if_set )
1338 split_if_set = new Node_List(area);
1339 split_if_set->push(use);
1340 }
1341 if( use->is_Bool() ) {
1342 if( !split_bool_set )
1343 split_bool_set = new Node_List(area);
1344 split_bool_set->push(use);
1345 }
1346 if( use->Opcode() == Op_CreateEx ) {
1347 if( !split_cex_set )
1348 split_cex_set = new Node_List(area);
1349 split_cex_set->push(use);
1350 }
1351
1352
1353 // Get "block" use is in
1354 uint idx = 0;
1355 while( use->in(idx) != old ) idx++;
1356 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1357 assert( !loop->is_member( get_loop( prev ) ), "" );
1358 Node *cfg = prev->_idx >= new_counter
1359 ? prev->in(2)
1360 : idom(prev);
1361 if( use->is_Phi() ) // Phi use is in prior block
1362 cfg = prev->in(idx); // NOT in block of Phi itself
1363 if (cfg->is_top()) { // Use is dead?
1364 _igvn.hash_delete(use);
1365 _igvn._worklist.push(use);
1366 use->set_req(idx, C->top());
1367 continue;
1368 }
1369
1370 while( !loop->is_member( get_loop( cfg ) ) ) {
1371 prev = cfg;
1372 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1373 }
1374 // If the use occurs after merging several exits from the loop, then
1375 // old value must have dominated all those exits. Since the same old
1376 // value was used on all those exits we did not need a Phi at this
1377 // merge point. NOW we do need a Phi here. Each loop exit value
1378 // is now merged with the peeled body exit; each exit gets its own
1379 // private Phi and those Phis need to be merged here.
1380 Node *phi;
1381 if( prev->is_Region() ) {
1382 if( idx == 0 ) { // Updating control edge?
1383 phi = prev; // Just use existing control
1384 } else { // Else need a new Phi
1385 phi = PhiNode::make( prev, old );
1386 // Now recursively fix up the new uses of old!
1387 for( uint i = 1; i < prev->req(); i++ ) {
1388 worklist.push(phi); // Onto worklist once for each 'old' input
1389 }
1390 }
1391 } else {
1392 // Get new RegionNode merging old and new loop exits
1393 prev = old_new[prev->_idx];
1394 assert( prev, "just made this in step 7" );
1395 if( idx == 0 ) { // Updating control edge?
1396 phi = prev; // Just use existing control
1397 } else { // Else need a new Phi
1398 // Make a new Phi merging data values properly
1399 phi = PhiNode::make( prev, old );
1400 phi->set_req( 1, nnn );
1401 }
1402 }
1403 // If inserting a new Phi, check for prior hits
1404 if( idx != 0 ) {
1405 Node *hit = _igvn.hash_find_insert(phi);
1406 if( hit == NULL ) {
1407 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1408 } else { // or
1409 // Remove the new phi from the graph and use the hit
1410 _igvn.remove_dead_node(phi);
1411 phi = hit; // Use existing phi
1412 }
1413 set_ctrl(phi, prev);
1414 }
1415 // Make 'use' use the Phi instead of the old loop body exit value
1416 _igvn.hash_delete(use);
1417 _igvn._worklist.push(use);
1418 use->set_req(idx, phi);
1419 if( use->_idx >= new_counter ) { // If updating new phis
1420 // Not needed for correctness, but prevents a weak assert
1421 // in AddPNode from tripping (when we end up with different
1422 // base & derived Phis that will become the same after
1423 // IGVN does CSE).
1424 Node *hit = _igvn.hash_find_insert(use);
1425 if( hit ) // Go ahead and re-hash for hits.
1426 _igvn.subsume_node( use, hit );
1427 }
1428
1429 // If 'use' was in the loop-exit block, it now needs to be sunk
1430 // below the post-loop merge point.
1431 sink_use( use, prev );
1432 }
1433 }
1434 }
1435
1436 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1437 // the loop uses a condition set in the loop. The original IF probably
1438 // takes control from one or more OLD Regions (which in turn get from NEW
1439 // Regions). In any case, there will be a set of Phis for each merge point
1440 // from the IF up to where the original BOOL def exists the loop.
1441 if( split_if_set ) {
1442 while( split_if_set->size() ) {
1443 Node *iff = split_if_set->pop();
1444 if( iff->in(1)->is_Phi() ) {
1445 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1446 _igvn.hash_delete(iff);
1447 _igvn._worklist.push(iff);
1448 iff->set_req(1, b);
1449 }
1450 }
1451 }
1452 if( split_bool_set ) {
1453 while( split_bool_set->size() ) {
1454 Node *b = split_bool_set->pop();
1455 Node *phi = b->in(1);
1456 assert( phi->is_Phi(), "" );
1457 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1458 _igvn.hash_delete(b);
1459 _igvn._worklist.push(b);
1460 b->set_req(1, cmp);
1461 }
1462 }
1463 if( split_cex_set ) {
1464 while( split_cex_set->size() ) {
1465 Node *b = split_cex_set->pop();
1466 assert( b->in(0)->is_Region(), "" );
1467 assert( b->in(1)->is_Phi(), "" );
1468 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1469 split_up( b, b->in(0), NULL );
1470 }
1471 }
1472
1473 }
1474
1475
1476 //---------------------- stride_of_possible_iv -------------------------------------
1477 // Looks for an iff/bool/comp with one operand of the compare
1478 // being a cycle involving an add and a phi,
1479 // with an optional truncation (left-shift followed by a right-shift)
1480 // of the add. Returns zero if not an iv.
1481 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1482 Node* trunc1 = NULL;
1483 Node* trunc2 = NULL;
1484 const TypeInt* ttype = NULL;
1485 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1486 return 0;
1487 }
1488 BoolNode* bl = iff->in(1)->as_Bool();
1489 Node* cmp = bl->in(1);
1490 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1491 return 0;
1492 }
1493 // Must have an invariant operand
1494 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1495 return 0;
1496 }
1497 Node* add2 = NULL;
1498 Node* cmp1 = cmp->in(1);
1499 if (cmp1->is_Phi()) {
1500 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1501 Node* phi = cmp1;
1502 for (uint i = 1; i < phi->req(); i++) {
1503 Node* in = phi->in(i);
1504 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1505 &trunc1, &trunc2, &ttype);
1506 if (add && add->in(1) == phi) {
1507 add2 = add->in(2);
1508 break;
1509 }
1510 }
1511 } else {
1512 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1513 Node* addtrunc = cmp1;
1514 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1515 &trunc1, &trunc2, &ttype);
1516 if (add && add->in(1)->is_Phi()) {
1517 Node* phi = add->in(1);
1518 for (uint i = 1; i < phi->req(); i++) {
1519 if (phi->in(i) == addtrunc) {
1520 add2 = add->in(2);
1521 break;
1522 }
1523 }
1524 }
1525 }
1526 if (add2 != NULL) {
1527 const TypeInt* add2t = _igvn.type(add2)->is_int();
1528 if (add2t->is_con()) {
1529 return add2t->get_con();
1530 }
1531 }
1532 return 0;
1533 }
1534
1535
1536 //---------------------- stay_in_loop -------------------------------------
1537 // Return the (unique) control output node that's in the loop (if it exists.)
1538 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1539 Node* unique = NULL;
1540 if (!n) return NULL;
1541 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1542 Node* use = n->fast_out(i);
1543 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1544 if (unique != NULL) {
1545 return NULL;
1546 }
1547 unique = use;
1548 }
1549 }
1550 return unique;
1551 }
1552
1553 //------------------------------ register_node -------------------------------------
1554 // Utility to register node "n" with PhaseIdealLoop
1555 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1556 _igvn.register_new_node_with_optimizer(n);
1557 loop->_body.push(n);
1558 if (n->is_CFG()) {
1559 set_loop(n, loop);
1560 set_idom(n, pred, ddepth);
1561 } else {
1562 set_ctrl(n, pred);
1563 }
1564 }
1565
1566 //------------------------------ proj_clone -------------------------------------
1567 // Utility to create an if-projection
1568 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1569 ProjNode* c = p->clone()->as_Proj();
1570 c->set_req(0, iff);
1571 return c;
1572 }
1573
1574 //------------------------------ short_circuit_if -------------------------------------
1575 // Force the iff control output to be the live_proj
1576 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1577 int proj_con = live_proj->_con;
1578 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1579 Node *con = _igvn.intcon(proj_con);
1580 set_ctrl(con, C->root());
1581 if (iff) {
1582 iff->set_req(1, con);
1583 }
1584 return con;
1585 }
1586
1587 //------------------------------ insert_if_before_proj -------------------------------------
1588 // Insert a new if before an if projection (* - new node)
1589 //
1590 // before
1591 // if(test)
1592 // / \
1593 // v v
1594 // other-proj proj (arg)
1595 //
1596 // after
1597 // if(test)
1598 // / \
1599 // / v
1600 // | * proj-clone
1601 // v |
1602 // other-proj v
1603 // * new_if(relop(cmp[IU](left,right)))
1604 // / \
1605 // v v
1606 // * new-proj proj
1607 // (returned)
1608 //
1609 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1610 IfNode* iff = proj->in(0)->as_If();
1611 IdealLoopTree *loop = get_loop(proj);
1612 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1613 int ddepth = dom_depth(proj);
1614
1615 _igvn.hash_delete(iff);
1616 _igvn._worklist.push(iff);
1617 _igvn.hash_delete(proj);
1618 _igvn._worklist.push(proj);
1619
1620 proj->set_req(0, NULL); // temporary disconnect
1621 ProjNode* proj2 = proj_clone(proj, iff);
1622 register_node(proj2, loop, iff, ddepth);
1623
1624 Node* cmp = Signed ? (Node*) new (C,3)CmpINode(left, right) : (Node*) new (C,3)CmpUNode(left, right);
1625 register_node(cmp, loop, proj2, ddepth);
1626
1627 BoolNode* bol = new (C,2)BoolNode(cmp, relop);
1628 register_node(bol, loop, proj2, ddepth);
1629
1630 IfNode* new_if = new (C,2)IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1631 register_node(new_if, loop, proj2, ddepth);
1632
1633 proj->set_req(0, new_if); // reattach
1634 set_idom(proj, new_if, ddepth);
1635
1636 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1637 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1638
1639 return new_exit;
1640 }
1641
1642 //------------------------------ insert_region_before_proj -------------------------------------
1643 // Insert a region before an if projection (* - new node)
1644 //
1645 // before
1646 // if(test)
1647 // / |
1648 // v |
1649 // proj v
1650 // other-proj
1651 //
1652 // after
1653 // if(test)
1654 // / |
1655 // v |
1656 // * proj-clone v
1657 // | other-proj
1658 // v
1659 // * new-region
1660 // |
1661 // v
1662 // * dum_if
1663 // / \
1664 // v \
1665 // * dum-proj v
1666 // proj
1667 //
1668 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1669 IfNode* iff = proj->in(0)->as_If();
1670 IdealLoopTree *loop = get_loop(proj);
1671 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1672 int ddepth = dom_depth(proj);
1673
1674 _igvn.hash_delete(iff);
1675 _igvn._worklist.push(iff);
1676 _igvn.hash_delete(proj);
1677 _igvn._worklist.push(proj);
1678
1679 proj->set_req(0, NULL); // temporary disconnect
1680 ProjNode* proj2 = proj_clone(proj, iff);
1681 register_node(proj2, loop, iff, ddepth);
1682
1683 RegionNode* reg = new (C,2)RegionNode(2);
1684 reg->set_req(1, proj2);
1685 register_node(reg, loop, iff, ddepth);
1686
1687 IfNode* dum_if = new (C,2)IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
1688 register_node(dum_if, loop, reg, ddepth);
1689
1690 proj->set_req(0, dum_if); // reattach
1691 set_idom(proj, dum_if, ddepth);
1692
1693 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
1694 register_node(dum_proj, loop, dum_if, ddepth);
1695
1696 return reg;
1697 }
1698
1699 //------------------------------ insert_cmpi_loop_exit -------------------------------------
1700 // Clone a signed compare loop exit from an unsigned compare and
1701 // insert it before the unsigned cmp on the stay-in-loop path.
1702 // All new nodes inserted in the dominator tree between the original
1703 // if and it's projections. The original if test is replaced with
1704 // a constant to force the stay-in-loop path.
1705 //
1706 // This is done to make sure that the original if and it's projections
1707 // still dominate the same set of control nodes, that the ctrl() relation
1708 // from data nodes to them is preserved, and that their loop nesting is
1709 // preserved.
1710 //
1711 // before
1712 // if(i <u limit) unsigned compare loop exit
1713 // / |
1714 // v v
1715 // exit-proj stay-in-loop-proj
1716 //
1717 // after
1718 // if(stay-in-loop-const) original if
1719 // / |
1720 // / v
1721 // / if(i < limit) new signed test
1722 // / / |
1723 // / / v
1724 // / / if(i <u limit) new cloned unsigned test
1725 // / / / |
1726 // v v v |
1727 // region |
1728 // | |
1729 // dum-if |
1730 // / | |
1731 // ether | |
1732 // v v
1733 // exit-proj stay-in-loop-proj
1734 //
1735 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
1736 const bool Signed = true;
1737 const bool Unsigned = false;
1738
1739 BoolNode* bol = if_cmpu->in(1)->as_Bool();
1740 if (bol->_test._test != BoolTest::lt) return NULL;
1741 CmpNode* cmpu = bol->in(1)->as_Cmp();
1742 if (cmpu->Opcode() != Op_CmpU) return NULL;
1743 int stride = stride_of_possible_iv(if_cmpu);
1744 if (stride == 0) return NULL;
1745
1746 ProjNode* lp_continue = stay_in_loop(if_cmpu, loop)->as_Proj();
1747 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
1748
1749 Node* limit = NULL;
1750 if (stride > 0) {
1751 limit = cmpu->in(2);
1752 } else {
1753 limit = _igvn.makecon(TypeInt::ZERO);
1754 set_ctrl(limit, C->root());
1755 }
1756 // Create a new region on the exit path
1757 RegionNode* reg = insert_region_before_proj(lp_exit);
1758
1759 // Clone the if-cmpu-true-false using a signed compare
1760 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
1761 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
1762 reg->add_req(cmpi_exit);
1763
1764 // Clone the if-cmpu-true-false
1765 BoolTest::mask rel_u = bol->_test._test;
1766 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
1767 reg->add_req(cmpu_exit);
1768
1769 // Force original if to stay in loop.
1770 short_circuit_if(if_cmpu, lp_continue);
1771
1772 return cmpi_exit->in(0)->as_If();
1773 }
1774
1775 //------------------------------ remove_cmpi_loop_exit -------------------------------------
1776 // Remove a previously inserted signed compare loop exit.
1777 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
1778 Node* lp_proj = stay_in_loop(if_cmp, loop);
1779 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
1780 stay_in_loop(lp_proj, loop)->is_If() &&
1781 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
1782 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
1783 set_ctrl(con, C->root());
1784 if_cmp->set_req(1, con);
1785 }
1786
1787 //------------------------------ scheduled_nodelist -------------------------------------
1788 // Create a post order schedule of nodes that are in the
1789 // "member" set. The list is returned in "sched".
1790 // The first node in "sched" is the loop head, followed by
1791 // nodes which have no inputs in the "member" set, and then
1792 // followed by the nodes that have an immediate input dependence
1793 // on a node in "sched".
1794 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
1795
1796 assert(member.test(loop->_head->_idx), "loop head must be in member set");
1797 Arena *a = Thread::current()->resource_area();
1798 VectorSet visited(a);
1799 Node_Stack nstack(a, loop->_body.size());
1800
1801 Node* n = loop->_head; // top of stack is cached in "n"
1802 uint idx = 0;
1803 visited.set(n->_idx);
1804
1805 // Initially push all with no inputs from within member set
1806 for(uint i = 0; i < loop->_body.size(); i++ ) {
1807 Node *elt = loop->_body.at(i);
1808 if (member.test(elt->_idx)) {
1809 bool found = false;
1810 for (uint j = 0; j < elt->req(); j++) {
1811 Node* def = elt->in(j);
1812 if (def && member.test(def->_idx) && def != elt) {
1813 found = true;
1814 break;
1815 }
1816 }
1817 if (!found && elt != loop->_head) {
1818 nstack.push(n, idx);
1819 n = elt;
1820 assert(!visited.test(n->_idx), "not seen yet");
1821 visited.set(n->_idx);
1822 }
1823 }
1824 }
1825
1826 // traverse out's that are in the member set
1827 while (true) {
1828 if (idx < n->outcnt()) {
1829 Node* use = n->raw_out(idx);
1830 idx++;
1831 if (!visited.test_set(use->_idx)) {
1832 if (member.test(use->_idx)) {
1833 nstack.push(n, idx);
1834 n = use;
1835 idx = 0;
1836 }
1837 }
1838 } else {
1839 // All outputs processed
1840 sched.push(n);
1841 if (nstack.is_empty()) break;
1842 n = nstack.node();
1843 idx = nstack.index();
1844 nstack.pop();
1845 }
1846 }
1847 }
1848
1849
1850 //------------------------------ has_use_in_set -------------------------------------
1851 // Has a use in the vector set
1852 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
1853 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1854 Node* use = n->fast_out(j);
1855 if (vset.test(use->_idx)) {
1856 return true;
1857 }
1858 }
1859 return false;
1860 }
1861
1862
1863 //------------------------------ has_use_internal_to_set -------------------------------------
1864 // Has use internal to the vector set (ie. not in a phi at the loop head)
1865 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
1866 Node* head = loop->_head;
1867 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1868 Node* use = n->fast_out(j);
1869 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
1870 return true;
1871 }
1872 }
1873 return false;
1874 }
1875
1876
1877 //------------------------------ clone_for_use_outside_loop -------------------------------------
1878 // clone "n" for uses that are outside of loop
1879 void PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
1880
1881 assert(worklist.size() == 0, "should be empty");
1882 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1883 Node* use = n->fast_out(j);
1884 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
1885 worklist.push(use);
1886 }
1887 }
1888 while( worklist.size() ) {
1889 Node *use = worklist.pop();
1890 if (!has_node(use) || use->in(0) == C->top()) continue;
1891 uint j;
1892 for (j = 0; j < use->req(); j++) {
1893 if (use->in(j) == n) break;
1894 }
1895 assert(j < use->req(), "must be there");
1896
1897 // clone "n" and insert it between the inputs of "n" and the use outside the loop
1898 Node* n_clone = n->clone();
1899 _igvn.hash_delete(use);
1900 use->set_req(j, n_clone);
1901 _igvn._worklist.push(use);
1902 Node* use_c;
1903 if (!use->is_Phi()) {
1904 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
1905 } else {
1906 // Use in a phi is considered a use in the associated predecessor block
1907 use_c = use->in(0)->in(j);
1908 }
1909 set_ctrl(n_clone, use_c);
1910 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
1911 get_loop(use_c)->_body.push(n_clone);
1912 _igvn.register_new_node_with_optimizer(n_clone);
1913 #if !defined(PRODUCT)
1914 if (TracePartialPeeling) {
1915 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
1916 }
1917 #endif
1918 }
1919 }
1920
1921
1922 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
1923 // clone "n" for special uses that are in the not_peeled region.
1924 // If these def-uses occur in separate blocks, the code generator
1925 // marks the method as not compilable. For example, if a "BoolNode"
1926 // is in a different basic block than the "IfNode" that uses it, then
1927 // the compilation is aborted in the code generator.
1928 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1929 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
1930 if (n->is_Phi() || n->is_Load()) {
1931 return;
1932 }
1933 assert(worklist.size() == 0, "should be empty");
1934 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1935 Node* use = n->fast_out(j);
1936 if ( not_peel.test(use->_idx) &&
1937 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
1938 use->in(1) == n) {
1939 worklist.push(use);
1940 }
1941 }
1942 if (worklist.size() > 0) {
1943 // clone "n" and insert it between inputs of "n" and the use
1944 Node* n_clone = n->clone();
1945 loop->_body.push(n_clone);
1946 _igvn.register_new_node_with_optimizer(n_clone);
1947 set_ctrl(n_clone, get_ctrl(n));
1948 sink_list.push(n_clone);
1949 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
1950 #if !defined(PRODUCT)
1951 if (TracePartialPeeling) {
1952 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
1953 }
1954 #endif
1955 while( worklist.size() ) {
1956 Node *use = worklist.pop();
1957 _igvn.hash_delete(use);
1958 _igvn._worklist.push(use);
1959 for (uint j = 1; j < use->req(); j++) {
1960 if (use->in(j) == n) {
1961 use->set_req(j, n_clone);
1962 }
1963 }
1964 }
1965 }
1966 }
1967
1968
1969 //------------------------------ insert_phi_for_loop -------------------------------------
1970 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1971 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
1972 Node *phi = PhiNode::make(lp, back_edge_val);
1973 phi->set_req(LoopNode::EntryControl, lp_entry_val);
1974 // Use existing phi if it already exists
1975 Node *hit = _igvn.hash_find_insert(phi);
1976 if( hit == NULL ) {
1977 _igvn.register_new_node_with_optimizer(phi);
1978 set_ctrl(phi, lp);
1979 } else {
1980 // Remove the new phi from the graph and use the hit
1981 _igvn.remove_dead_node(phi);
1982 phi = hit;
1983 }
1984 _igvn.hash_delete(use);
1985 _igvn._worklist.push(use);
1986 use->set_req(idx, phi);
1987 }
1988
1989 #ifdef ASSERT
1990 //------------------------------ is_valid_loop_partition -------------------------------------
1991 // Validate the loop partition sets: peel and not_peel
1992 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
1993 VectorSet& not_peel ) {
1994 uint i;
1995 // Check that peel_list entries are in the peel set
1996 for (i = 0; i < peel_list.size(); i++) {
1997 if (!peel.test(peel_list.at(i)->_idx)) {
1998 return false;
1999 }
2000 }
2001 // Check at loop members are in one of peel set or not_peel set
2002 for (i = 0; i < loop->_body.size(); i++ ) {
2003 Node *def = loop->_body.at(i);
2004 uint di = def->_idx;
2005 // Check that peel set elements are in peel_list
2006 if (peel.test(di)) {
2007 if (not_peel.test(di)) {
2008 return false;
2009 }
2010 // Must be in peel_list also
2011 bool found = false;
2012 for (uint j = 0; j < peel_list.size(); j++) {
2013 if (peel_list.at(j)->_idx == di) {
2014 found = true;
2015 break;
2016 }
2017 }
2018 if (!found) {
2019 return false;
2020 }
2021 } else if (not_peel.test(di)) {
2022 if (peel.test(di)) {
2023 return false;
2024 }
2025 } else {
2026 return false;
2027 }
2028 }
2029 return true;
2030 }
2031
2032 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2033 // Ensure a use outside of loop is of the right form
2034 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2035 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2036 return (use->is_Phi() &&
2037 use_c->is_Region() && use_c->req() == 3 &&
2038 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2039 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2040 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2041 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2042 }
2043
2044 //------------------------------ is_valid_clone_loop_form -------------------------------------
2045 // Ensure that all uses outside of loop are of the right form
2046 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2047 uint orig_exit_idx, uint clone_exit_idx) {
2048 uint len = peel_list.size();
2049 for (uint i = 0; i < len; i++) {
2050 Node *def = peel_list.at(i);
2051
2052 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2053 Node *use = def->fast_out(j);
2054 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2055 if (!loop->is_member(get_loop(use_c))) {
2056 // use is not in the loop, check for correct structure
2057 if (use->in(0) == def) {
2058 // Okay
2059 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2060 return false;
2061 }
2062 }
2063 }
2064 }
2065 return true;
2066 }
2067 #endif
2068
2069 //------------------------------ partial_peel -------------------------------------
2070 // Partially peel (aka loop rotation) the top portion of a loop (called
2071 // the peel section below) by cloning it and placing one copy just before
2072 // the new loop head and the other copy at the bottom of the new loop.
2073 //
2074 // before after where it came from
2075 //
2076 // stmt1 stmt1
2077 // loop: stmt2 clone
2078 // stmt2 if condA goto exitA clone
2079 // if condA goto exitA new_loop: new
2080 // stmt3 stmt3 clone
2081 // if !condB goto loop if condB goto exitB clone
2082 // exitB: stmt2 orig
2083 // stmt4 if !condA goto new_loop orig
2084 // exitA: goto exitA
2085 // exitB:
2086 // stmt4
2087 // exitA:
2088 //
2089 // Step 1: find the cut point: an exit test on probable
2090 // induction variable.
2091 // Step 2: schedule (with cloning) operations in the peel
2092 // section that can be executed after the cut into
2093 // the section that is not peeled. This may need
2094 // to clone operations into exit blocks. For
2095 // instance, a reference to A[i] in the not-peel
2096 // section and a reference to B[i] in an exit block
2097 // may cause a left-shift of i by 2 to be placed
2098 // in the peel block. This step will clone the left
2099 // shift into the exit block and sink the left shift
2100 // from the peel to the not-peel section.
2101 // Step 3: clone the loop, retarget the control, and insert
2102 // phis for values that are live across the new loop
2103 // head. This is very dependent on the graph structure
2104 // from clone_loop. It creates region nodes for
2105 // exit control and associated phi nodes for values
2106 // flow out of the loop through that exit. The region
2107 // node is dominated by the clone's control projection.
2108 // So the clone's peel section is placed before the
2109 // new loop head, and the clone's not-peel section is
2110 // forms the top part of the new loop. The original
2111 // peel section forms the tail of the new loop.
2112 // Step 4: update the dominator tree and recompute the
2113 // dominator depth.
2114 //
2115 // orig
2116 //
2117 // stmt1
2118 // |
2119 // v
2120 // loop<----+
2121 // | |
2122 // stmt2 |
2123 // | |
2124 // v |
2125 // ifA |
2126 // / | |
2127 // v v |
2128 // false true ^ <-- last_peel
2129 // / | |
2130 // / ===|==cut |
2131 // / stmt3 | <-- first_not_peel
2132 // / | |
2133 // | v |
2134 // v ifB |
2135 // exitA: / \ |
2136 // / \ |
2137 // v v |
2138 // false true |
2139 // / \ |
2140 // / ----+
2141 // |
2142 // v
2143 // exitB:
2144 // stmt4
2145 //
2146 //
2147 // after clone loop
2148 //
2149 // stmt1
2150 // / \
2151 // clone / \ orig
2152 // / \
2153 // / \
2154 // v v
2155 // +---->loop loop<----+
2156 // | | | |
2157 // | stmt2 stmt2 |
2158 // | | | |
2159 // | v v |
2160 // | ifA ifA |
2161 // | | \ / | |
2162 // | v v v v |
2163 // ^ true false false true ^ <-- last_peel
2164 // | | ^ \ / | |
2165 // | cut==|== \ \ / ===|==cut |
2166 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2167 // | | dom | | | |
2168 // | v \ 1v v2 v |
2169 // | ifB regionA ifB |
2170 // | / \ | / \ |
2171 // | / \ v / \ |
2172 // | v v exitA: v v |
2173 // | true false false true |
2174 // | / ^ \ / \ |
2175 // +---- \ \ / ----+
2176 // dom \ /
2177 // \ 1v v2
2178 // regionB
2179 // |
2180 // v
2181 // exitB:
2182 // stmt4
2183 //
2184 //
2185 // after partial peel
2186 //
2187 // stmt1
2188 // /
2189 // clone / orig
2190 // / TOP
2191 // / \
2192 // v v
2193 // TOP->region region----+
2194 // | | |
2195 // stmt2 stmt2 |
2196 // | | |
2197 // v v |
2198 // ifA ifA |
2199 // | \ / | |
2200 // v v v v |
2201 // true false false true | <-- last_peel
2202 // | ^ \ / +------|---+
2203 // +->newloop \ \ / === ==cut | |
2204 // | stmt3 \ \ / TOP | |
2205 // | | dom | | stmt3 | | <-- first_not_peel
2206 // | v \ 1v v2 v | |
2207 // | ifB regionA ifB ^ v
2208 // | / \ | / \ | |
2209 // | / \ v / \ | |
2210 // | v v exitA: v v | |
2211 // | true false false true | |
2212 // | / ^ \ / \ | |
2213 // | | \ \ / v | |
2214 // | | dom \ / TOP | |
2215 // | | \ 1v v2 | |
2216 // ^ v regionB | |
2217 // | | | | |
2218 // | | v ^ v
2219 // | | exitB: | |
2220 // | | stmt4 | |
2221 // | +------------>-----------------+ |
2222 // | |
2223 // +-----------------<---------------------+
2224 //
2225 //
2226 // final graph
2227 //
2228 // stmt1
2229 // |
2230 // v
2231 // ........> ifA clone
2232 // : / |
2233 // dom / |
2234 // : v v
2235 // : false true
2236 // : | |
2237 // : | stmt2 clone
2238 // : | |
2239 // : | v
2240 // : | newloop<-----+
2241 // : | | |
2242 // : | stmt3 clone |
2243 // : | | |
2244 // : | v |
2245 // : | ifB |
2246 // : | / \ |
2247 // : | v v |
2248 // : | false true |
2249 // : | | | |
2250 // : | v stmt2 |
2251 // : | exitB: | |
2252 // : | stmt4 v |
2253 // : | ifA orig |
2254 // : | / \ |
2255 // : | / \ |
2256 // : | v v |
2257 // : | false true |
2258 // : | / \ |
2259 // : v v -----+
2260 // RegionA
2261 // |
2262 // v
2263 // exitA
2264 //
2265 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2266
2267 if (!loop->_head->is_Loop()) {
2268 return false; }
2269
2270 LoopNode *head = loop->_head->as_Loop();
2271
2272 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2273 return false;
2274 }
2275
2276 // Check for complex exit control
2277 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2278 Node *n = loop->_body.at(ii);
2279 int opc = n->Opcode();
2280 if (n->is_Call() ||
2281 opc == Op_Catch ||
2282 opc == Op_CatchProj ||
2283 opc == Op_Jump ||
2284 opc == Op_JumpProj) {
2285 #if !defined(PRODUCT)
2286 if (TracePartialPeeling) {
2287 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2288 }
2289 #endif
2290 return false;
2291 }
2292 }
2293
2294 int dd = dom_depth(head);
2295
2296 // Step 1: find cut point
2297
2298 // Walk up dominators to loop head looking for first loop exit
2299 // which is executed on every path thru loop.
2300 IfNode *peel_if = NULL;
2301 IfNode *peel_if_cmpu = NULL;
2302
2303 Node *iff = loop->tail();
2304 while( iff != head ) {
2305 if( iff->is_If() ) {
2306 Node *ctrl = get_ctrl(iff->in(1));
2307 if (ctrl->is_top()) return false; // Dead test on live IF.
2308 // If loop-varying exit-test, check for induction variable
2309 if( loop->is_member(get_loop(ctrl)) &&
2310 loop->is_loop_exit(iff) &&
2311 is_possible_iv_test(iff)) {
2312 Node* cmp = iff->in(1)->in(1);
2313 if (cmp->Opcode() == Op_CmpI) {
2314 peel_if = iff->as_If();
2315 } else {
2316 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2317 peel_if_cmpu = iff->as_If();
2318 }
2319 }
2320 }
2321 iff = idom(iff);
2322 }
2323 // Prefer signed compare over unsigned compare.
2324 IfNode* new_peel_if = NULL;
2325 if (peel_if == NULL) {
2326 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2327 return false; // No peel point found
2328 }
2329 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2330 if (new_peel_if == NULL) {
2331 return false; // No peel point found
2332 }
2333 peel_if = new_peel_if;
2334 }
2335 Node* last_peel = stay_in_loop(peel_if, loop);
2336 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2337 if (first_not_peeled == NULL || first_not_peeled == head) {
2338 return false;
2339 }
2340
2341 #if !defined(PRODUCT)
2342 if (TracePartialPeeling) {
2343 tty->print_cr("before partial peel one iteration");
2344 Node_List wl;
2345 Node* t = head->in(2);
2346 while (true) {
2347 wl.push(t);
2348 if (t == head) break;
2349 t = idom(t);
2350 }
2351 while (wl.size() > 0) {
2352 Node* tt = wl.pop();
2353 tt->dump();
2354 if (tt == last_peel) tty->print_cr("-- cut --");
2355 }
2356 }
2357 #endif
2358 ResourceArea *area = Thread::current()->resource_area();
2359 VectorSet peel(area);
2360 VectorSet not_peel(area);
2361 Node_List peel_list(area);
2362 Node_List worklist(area);
2363 Node_List sink_list(area);
2364
2365 // Set of cfg nodes to peel are those that are executable from
2366 // the head through last_peel.
2367 assert(worklist.size() == 0, "should be empty");
2368 worklist.push(head);
2369 peel.set(head->_idx);
2370 while (worklist.size() > 0) {
2371 Node *n = worklist.pop();
2372 if (n != last_peel) {
2373 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2374 Node* use = n->fast_out(j);
2375 if (use->is_CFG() &&
2376 loop->is_member(get_loop(use)) &&
2377 !peel.test_set(use->_idx)) {
2378 worklist.push(use);
2379 }
2380 }
2381 }
2382 }
2383
2384 // Set of non-cfg nodes to peel are those that are control
2385 // dependent on the cfg nodes.
2386 uint i;
2387 for(i = 0; i < loop->_body.size(); i++ ) {
2388 Node *n = loop->_body.at(i);
2389 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2390 if (peel.test(n_c->_idx)) {
2391 peel.set(n->_idx);
2392 } else {
2393 not_peel.set(n->_idx);
2394 }
2395 }
2396
2397 // Step 2: move operations from the peeled section down into the
2398 // not-peeled section
2399
2400 // Get a post order schedule of nodes in the peel region
2401 // Result in right-most operand.
2402 scheduled_nodelist(loop, peel, peel_list );
2403
2404 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2405
2406 // For future check for too many new phis
2407 uint old_phi_cnt = 0;
2408 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2409 Node* use = head->fast_out(j);
2410 if (use->is_Phi()) old_phi_cnt++;
2411 }
2412
2413 #if !defined(PRODUCT)
2414 if (TracePartialPeeling) {
2415 tty->print_cr("\npeeled list");
2416 }
2417 #endif
2418
2419 // Evacuate nodes in peel region into the not_peeled region if possible
2420 uint new_phi_cnt = 0;
2421 for (i = 0; i < peel_list.size();) {
2422 Node* n = peel_list.at(i);
2423 #if !defined(PRODUCT)
2424 if (TracePartialPeeling) n->dump();
2425 #endif
2426 bool incr = true;
2427 if ( !n->is_CFG() ) {
2428
2429 if ( has_use_in_set(n, not_peel) ) {
2430
2431 // If not used internal to the peeled region,
2432 // move "n" from peeled to not_peeled region.
2433
2434 if ( !has_use_internal_to_set(n, peel, loop) ) {
2435
2436 // if not pinned and not a load (which maybe anti-dependent on a store)
2437 // and not a CMove (Matcher expects only bool->cmove).
2438 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2439 clone_for_use_outside_loop( loop, n, worklist );
2440
2441 sink_list.push(n);
2442 peel >>= n->_idx; // delete n from peel set.
2443 not_peel <<= n->_idx; // add n to not_peel set.
2444 peel_list.remove(i);
2445 incr = false;
2446 #if !defined(PRODUCT)
2447 if (TracePartialPeeling) {
2448 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2449 n->_idx, get_ctrl(n)->_idx);
2450 }
2451 #endif
2452 }
2453 } else {
2454 // Otherwise check for special def-use cases that span
2455 // the peel/not_peel boundary such as bool->if
2456 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2457 new_phi_cnt++;
2458 }
2459 }
2460 }
2461 if (incr) i++;
2462 }
2463
2464 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2465 #if !defined(PRODUCT)
2466 if (TracePartialPeeling) {
2467 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2468 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2469 }
2470 #endif
2471 if (new_peel_if != NULL) {
2472 remove_cmpi_loop_exit(new_peel_if, loop);
2473 }
2474 // Inhibit more partial peeling on this loop
2475 assert(!head->is_partial_peel_loop(), "not partial peeled");
2476 head->mark_partial_peel_failed();
2477 return false;
2478 }
2479
2480 // Step 3: clone loop, retarget control, and insert new phis
2481
2482 // Create new loop head for new phis and to hang
2483 // the nodes being moved (sinked) from the peel region.
2484 LoopNode* new_head = new (C, 3) LoopNode(last_peel, last_peel);
2485 _igvn.register_new_node_with_optimizer(new_head);
2486 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2487 first_not_peeled->set_req(0, new_head);
2488 set_loop(new_head, loop);
2489 loop->_body.push(new_head);
2490 not_peel.set(new_head->_idx);
2491 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2492 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2493
2494 while (sink_list.size() > 0) {
2495 Node* n = sink_list.pop();
2496 set_ctrl(n, new_head);
2497 }
2498
2499 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2500
2501 clone_loop( loop, old_new, dd );
2502
2503 const uint clone_exit_idx = 1;
2504 const uint orig_exit_idx = 2;
2505 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2506
2507 Node* head_clone = old_new[head->_idx];
2508 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2509 Node* orig_tail_clone = head_clone->in(2);
2510
2511 // Add phi if "def" node is in peel set and "use" is not
2512
2513 for(i = 0; i < peel_list.size(); i++ ) {
2514 Node *def = peel_list.at(i);
2515 if (!def->is_CFG()) {
2516 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2517 Node *use = def->fast_out(j);
2518 if (has_node(use) && use->in(0) != C->top() &&
2519 (!peel.test(use->_idx) ||
2520 (use->is_Phi() && use->in(0) == head)) ) {
2521 worklist.push(use);
2522 }
2523 }
2524 while( worklist.size() ) {
2525 Node *use = worklist.pop();
2526 for (uint j = 1; j < use->req(); j++) {
2527 Node* n = use->in(j);
2528 if (n == def) {
2529
2530 // "def" is in peel set, "use" is not in peel set
2531 // or "use" is in the entry boundary (a phi) of the peel set
2532
2533 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2534
2535 if ( loop->is_member(get_loop( use_c )) ) {
2536 // use is in loop
2537 if (old_new[use->_idx] != NULL) { // null for dead code
2538 Node* use_clone = old_new[use->_idx];
2539 _igvn.hash_delete(use);
2540 use->set_req(j, C->top());
2541 _igvn._worklist.push(use);
2542 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2543 }
2544 } else {
2545 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2546 // use is not in the loop, check if the live range includes the cut
2547 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2548 if (not_peel.test(lp_if->_idx)) {
2549 assert(j == orig_exit_idx, "use from original loop");
2550 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2551 }
2552 }
2553 }
2554 }
2555 }
2556 }
2557 }
2558
2559 // Step 3b: retarget control
2560
2561 // Redirect control to the new loop head if a cloned node in
2562 // the not_peeled region has control that points into the peeled region.
2563 // This necessary because the cloned peeled region will be outside
2564 // the loop.
2565 // from to
2566 // cloned-peeled <---+
2567 // new_head_clone: | <--+
2568 // cloned-not_peeled in(0) in(0)
2569 // orig-peeled
2570
2571 for(i = 0; i < loop->_body.size(); i++ ) {
2572 Node *n = loop->_body.at(i);
2573 if (!n->is_CFG() && n->in(0) != NULL &&
2574 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2575 Node* n_clone = old_new[n->_idx];
2576 _igvn.hash_delete(n_clone);
2577 n_clone->set_req(0, new_head_clone);
2578 _igvn._worklist.push(n_clone);
2579 }
2580 }
2581
2582 // Backedge of the surviving new_head (the clone) is original last_peel
2583 _igvn.hash_delete(new_head_clone);
2584 new_head_clone->set_req(LoopNode::LoopBackControl, last_peel);
2585 _igvn._worklist.push(new_head_clone);
2586
2587 // Cut first node in original not_peel set
2588 _igvn.hash_delete(new_head);
2589 new_head->set_req(LoopNode::EntryControl, C->top());
2590 new_head->set_req(LoopNode::LoopBackControl, C->top());
2591 _igvn._worklist.push(new_head);
2592
2593 // Copy head_clone back-branch info to original head
2594 // and remove original head's loop entry and
2595 // clone head's back-branch
2596 _igvn.hash_delete(head);
2597 _igvn.hash_delete(head_clone);
2598 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2599 head->set_req(LoopNode::LoopBackControl, C->top());
2600 head_clone->set_req(LoopNode::LoopBackControl, C->top());
2601 _igvn._worklist.push(head);
2602 _igvn._worklist.push(head_clone);
2603
2604 // Similarly modify the phis
2605 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2606 Node* use = head->fast_out(k);
2607 if (use->is_Phi() && use->outcnt() > 0) {
2608 Node* use_clone = old_new[use->_idx];
2609 _igvn.hash_delete(use);
2610 _igvn.hash_delete(use_clone);
2611 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2612 use->set_req(LoopNode::LoopBackControl, C->top());
2613 use_clone->set_req(LoopNode::LoopBackControl, C->top());
2614 _igvn._worklist.push(use);
2615 _igvn._worklist.push(use_clone);
2616 }
2617 }
2618
2619 // Step 4: update dominator tree and dominator depth
2620
2621 set_idom(head, orig_tail_clone, dd);
2622 recompute_dom_depth();
2623
2624 // Inhibit more partial peeling on this loop
2625 new_head_clone->set_partial_peel_loop();
2626 C->set_major_progress();
2627
2628 #if !defined(PRODUCT)
2629 if (TracePartialPeeling) {
2630 tty->print_cr("\nafter partial peel one iteration");
2631 Node_List wl(area);
2632 Node* t = last_peel;
2633 while (true) {
2634 wl.push(t);
2635 if (t == head_clone) break;
2636 t = idom(t);
2637 }
2638 while (wl.size() > 0) {
2639 Node* tt = wl.pop();
2640 if (tt == head) tty->print_cr("orig head");
2641 else if (tt == new_head_clone) tty->print_cr("new head");
2642 else if (tt == head_clone) tty->print_cr("clone head");
2643 tt->dump();
2644 }
2645 }
2646 #endif
2647 return true;
2648 }
2649
2650 //------------------------------reorg_offsets----------------------------------
2651 // Reorganize offset computations to lower register pressure. Mostly
2652 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2653 // then alive with the post-incremented trip counter forcing an extra
2654 // register move)
2655 void PhaseIdealLoop::reorg_offsets( IdealLoopTree *loop ) {
2656
2657 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2658 CountedLoopEndNode *cle = cl->loopexit();
2659 if( !cle ) return; // The occasional dead loop
2660 // Find loop exit control
2661 Node *exit = cle->proj_out(false);
2662 assert( exit->Opcode() == Op_IfFalse, "" );
2663
2664 // Check for the special case of folks using the pre-incremented
2665 // trip-counter on the fall-out path (forces the pre-incremented
2666 // and post-incremented trip counter to be live at the same time).
2667 // Fix this by adjusting to use the post-increment trip counter.
2668 Node *phi = cl->phi();
2669 if( !phi ) return; // Dead infinite loop
2670
2671 // Shape messed up, probably by iteration_split_impl
2672 if (phi->in(LoopNode::LoopBackControl) != cl->incr()) return;
2673
2674 bool progress = true;
2675 while (progress) {
2676 progress = false;
2677 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
2678 Node* use = phi->fast_out(i); // User of trip-counter
2679 if (!has_ctrl(use)) continue;
2680 Node *u_ctrl = get_ctrl(use);
2681 if( use->is_Phi() ) {
2682 u_ctrl = NULL;
2683 for( uint j = 1; j < use->req(); j++ )
2684 if( use->in(j) == phi )
2685 u_ctrl = dom_lca( u_ctrl, use->in(0)->in(j) );
2686 }
2687 IdealLoopTree *u_loop = get_loop(u_ctrl);
2688 // Look for loop-invariant use
2689 if( u_loop == loop ) continue;
2690 if( loop->is_member( u_loop ) ) continue;
2691 // Check that use is live out the bottom. Assuming the trip-counter
2692 // update is right at the bottom, uses of of the loop middle are ok.
2693 if( dom_lca( exit, u_ctrl ) != exit ) continue;
2694 // protect against stride not being a constant
2695 if( !cle->stride_is_con() ) continue;
2696 // Hit! Refactor use to use the post-incremented tripcounter.
2697 // Compute a post-increment tripcounter.
2698 Node *opaq = new (C, 2) Opaque2Node( C, cle->incr() );
2699 register_new_node( opaq, u_ctrl );
2700 Node *neg_stride = _igvn.intcon(-cle->stride_con());
2701 set_ctrl(neg_stride, C->root());
2702 Node *post = new (C, 3) AddINode( opaq, neg_stride);
2703 register_new_node( post, u_ctrl );
2704 _igvn.hash_delete(use);
2705 _igvn._worklist.push(use);
2706 for( uint j = 1; j < use->req(); j++ )
2707 if( use->in(j) == phi )
2708 use->set_req(j, post);
2709 // Since DU info changed, rerun loop
2710 progress = true;
2711 break;
2712 }
2713 }
2714
2715 }
2716