1 /*
2 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/connode.hpp"
29 #include "opto/divnode.hpp"
30 #include "opto/loopnode.hpp"
31 #include "opto/matcher.hpp"
32 #include "opto/mulnode.hpp"
33 #include "opto/movenode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37
38 //=============================================================================
39 //------------------------------split_thru_phi---------------------------------
40 // Split Node 'n' through merge point if there is enough win.
41 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
42 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
43 // ConvI2L may have type information on it which is unsafe to push up
44 // so disable this for now
45 return NULL;
46 }
47
48 int wins = 0;
49 assert(!n->is_CFG(), "");
50 assert(region->is_Region(), "");
51
52 const Type* type = n->bottom_type();
53 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
54 Node *phi;
55 if (t_oop != NULL && t_oop->is_known_instance_field()) {
56 int iid = t_oop->instance_id();
57 int index = C->get_alias_index(t_oop);
58 int offset = t_oop->offset();
59 phi = new PhiNode(region, type, NULL, iid, index, offset);
60 } else {
61 phi = PhiNode::make_blank(region, n);
62 }
63 uint old_unique = C->unique();
64 for (uint i = 1; i < region->req(); i++) {
65 Node *x;
66 Node* the_clone = NULL;
67 if (region->in(i) == C->top()) {
68 x = C->top(); // Dead path? Use a dead data op
69 } else {
70 x = n->clone(); // Else clone up the data op
71 the_clone = x; // Remember for possible deletion.
72 // Alter data node to use pre-phi inputs
73 if (n->in(0) == region)
74 x->set_req( 0, region->in(i) );
75 for (uint j = 1; j < n->req(); j++) {
76 Node *in = n->in(j);
77 if (in->is_Phi() && in->in(0) == region)
78 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
79 }
80 }
81 // Check for a 'win' on some paths
82 const Type *t = x->Value(&_igvn);
83
84 bool singleton = t->singleton();
85
86 // A TOP singleton indicates that there are no possible values incoming
87 // along a particular edge. In most cases, this is OK, and the Phi will
88 // be eliminated later in an Ideal call. However, we can't allow this to
89 // happen if the singleton occurs on loop entry, as the elimination of
90 // the PhiNode may cause the resulting node to migrate back to a previous
91 // loop iteration.
92 if (singleton && t == Type::TOP) {
93 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
94 // irreducible loop may not be indicated by an affirmative is_Loop());
95 // therefore, the only top we can split thru a phi is on a backedge of
96 // a loop.
97 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
98 }
99
100 if (singleton) {
101 wins++;
102 x = ((PhaseGVN&)_igvn).makecon(t);
103 } else {
104 // We now call Identity to try to simplify the cloned node.
105 // Note that some Identity methods call phase->type(this).
106 // Make sure that the type array is big enough for
107 // our new node, even though we may throw the node away.
108 // (Note: This tweaking with igvn only works because x is a new node.)
109 _igvn.set_type(x, t);
110 // If x is a TypeNode, capture any more-precise type permanently into Node
111 // otherwise it will be not updated during igvn->transform since
112 // igvn->type(x) is set to x->Value() already.
113 x->raise_bottom_type(t);
114 Node *y = x->Identity(&_igvn);
115 if (y != x) {
116 wins++;
117 x = y;
118 } else {
119 y = _igvn.hash_find(x);
120 if (y) {
121 wins++;
122 x = y;
123 } else {
124 // Else x is a new node we are keeping
125 // We do not need register_new_node_with_optimizer
126 // because set_type has already been called.
127 _igvn._worklist.push(x);
128 }
129 }
130 }
131 if (x != the_clone && the_clone != NULL)
132 _igvn.remove_dead_node(the_clone);
133 phi->set_req( i, x );
134 }
135 // Too few wins?
136 if (wins <= policy) {
137 _igvn.remove_dead_node(phi);
138 return NULL;
139 }
140
141 // Record Phi
142 register_new_node( phi, region );
143
144 for (uint i2 = 1; i2 < phi->req(); i2++) {
145 Node *x = phi->in(i2);
146 // If we commoned up the cloned 'x' with another existing Node,
147 // the existing Node picks up a new use. We need to make the
148 // existing Node occur higher up so it dominates its uses.
149 Node *old_ctrl;
150 IdealLoopTree *old_loop;
151
152 if (x->is_Con()) {
153 // Constant's control is always root.
154 set_ctrl(x, C->root());
155 continue;
156 }
157 // The occasional new node
158 if (x->_idx >= old_unique) { // Found a new, unplaced node?
159 old_ctrl = NULL;
160 old_loop = NULL; // Not in any prior loop
161 } else {
162 old_ctrl = get_ctrl(x);
163 old_loop = get_loop(old_ctrl); // Get prior loop
164 }
165 // New late point must dominate new use
166 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
167 if (new_ctrl == old_ctrl) // Nothing is changed
168 continue;
169
170 IdealLoopTree *new_loop = get_loop(new_ctrl);
171
172 // Don't move x into a loop if its uses are
173 // outside of loop. Otherwise x will be cloned
174 // for each use outside of this loop.
175 IdealLoopTree *use_loop = get_loop(region);
176 if (!new_loop->is_member(use_loop) &&
177 (old_loop == NULL || !new_loop->is_member(old_loop))) {
178 // Take early control, later control will be recalculated
179 // during next iteration of loop optimizations.
180 new_ctrl = get_early_ctrl(x);
181 new_loop = get_loop(new_ctrl);
182 }
183 // Set new location
184 set_ctrl(x, new_ctrl);
185 // If changing loop bodies, see if we need to collect into new body
186 if (old_loop != new_loop) {
187 if (old_loop && !old_loop->_child)
188 old_loop->_body.yank(x);
189 if (!new_loop->_child)
190 new_loop->_body.push(x); // Collect body info
191 }
192 }
193
194 return phi;
195 }
196
197 //------------------------------dominated_by------------------------------------
198 // Replace the dominated test with an obvious true or false. Place it on the
199 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
200 // live path up to the dominating control.
201 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
202 #ifndef PRODUCT
203 if (VerifyLoopOptimizations && PrintOpto) tty->print_cr("dominating test");
204 #endif
205
206
207 // prevdom is the dominating projection of the dominating test.
208 assert( iff->is_If(), "" );
209 assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
210 int pop = prevdom->Opcode();
211 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
212 if (flip) {
213 if (pop == Op_IfTrue)
214 pop = Op_IfFalse;
215 else
216 pop = Op_IfTrue;
217 }
218 // 'con' is set to true or false to kill the dominated test.
219 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
220 set_ctrl(con, C->root()); // Constant gets a new use
221 // Hack the dominated test
222 _igvn.replace_input_of(iff, 1, con);
223
224 // If I dont have a reachable TRUE and FALSE path following the IfNode then
225 // I can assume this path reaches an infinite loop. In this case it's not
226 // important to optimize the data Nodes - either the whole compilation will
227 // be tossed or this path (and all data Nodes) will go dead.
228 if (iff->outcnt() != 2) return;
229
230 // Make control-dependent data Nodes on the live path (path that will remain
231 // once the dominated IF is removed) become control-dependent on the
232 // dominating projection.
233 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
234
235 // Loop predicates may have depending checks which should not
236 // be skipped. For example, range check predicate has two checks
237 // for lower and upper bounds.
238 if (dp == NULL)
239 return;
240
241 ProjNode* dp_proj = dp->as_Proj();
242 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
243 if (exclude_loop_predicate &&
244 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
245 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
246 // If this is a range check (IfNode::is_range_check), do not
247 // reorder because Compile::allow_range_check_smearing might have
248 // changed the check.
249 return; // Let IGVN transformation change control dependence.
250 }
251
252 IdealLoopTree *old_loop = get_loop(dp);
253
254 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
255 Node* cd = dp->fast_out(i); // Control-dependent node
256 if (cd->depends_only_on_test()) {
257 assert(cd->in(0) == dp, "");
258 _igvn.replace_input_of(cd, 0, prevdom);
259 set_early_ctrl(cd);
260 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
261 if (old_loop != new_loop) {
262 if (!old_loop->_child) old_loop->_body.yank(cd);
263 if (!new_loop->_child) new_loop->_body.push(cd);
264 }
265 --i;
266 --imax;
267 }
268 }
269 }
270
271 //------------------------------has_local_phi_input----------------------------
272 // Return TRUE if 'n' has Phi inputs from its local block and no other
273 // block-local inputs (all non-local-phi inputs come from earlier blocks)
274 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
275 Node *n_ctrl = get_ctrl(n);
276 // See if some inputs come from a Phi in this block, or from before
277 // this block.
278 uint i;
279 for( i = 1; i < n->req(); i++ ) {
280 Node *phi = n->in(i);
281 if( phi->is_Phi() && phi->in(0) == n_ctrl )
282 break;
283 }
284 if( i >= n->req() )
285 return NULL; // No Phi inputs; nowhere to clone thru
286
287 // Check for inputs created between 'n' and the Phi input. These
288 // must split as well; they have already been given the chance
289 // (courtesy of a post-order visit) and since they did not we must
290 // recover the 'cost' of splitting them by being very profitable
291 // when splitting 'n'. Since this is unlikely we simply give up.
292 for( i = 1; i < n->req(); i++ ) {
293 Node *m = n->in(i);
294 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
295 // We allow the special case of AddP's with no local inputs.
296 // This allows us to split-up address expressions.
297 if (m->is_AddP() &&
298 get_ctrl(m->in(2)) != n_ctrl &&
299 get_ctrl(m->in(3)) != n_ctrl) {
300 // Move the AddP up to dominating point
301 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
302 continue;
303 }
304 return NULL;
305 }
306 }
307
308 return n_ctrl;
309 }
310
311 //------------------------------remix_address_expressions----------------------
312 // Rework addressing expressions to get the most loop-invariant stuff
313 // moved out. We'd like to do all associative operators, but it's especially
314 // important (common) to do address expressions.
315 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
316 if (!has_ctrl(n)) return NULL;
317 Node *n_ctrl = get_ctrl(n);
318 IdealLoopTree *n_loop = get_loop(n_ctrl);
319
320 // See if 'n' mixes loop-varying and loop-invariant inputs and
321 // itself is loop-varying.
322
323 // Only interested in binary ops (and AddP)
324 if( n->req() < 3 || n->req() > 4 ) return NULL;
325
326 Node *n1_ctrl = get_ctrl(n->in( 1));
327 Node *n2_ctrl = get_ctrl(n->in( 2));
328 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
329 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
330 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
331 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
332
333 // Does one of my inputs spin in a tighter loop than self?
334 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
335 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
336 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
337 return NULL; // Leave well enough alone
338
339 // Is at least one of my inputs loop-invariant?
340 if( n1_loop == n_loop &&
341 n2_loop == n_loop &&
342 n3_loop == n_loop )
343 return NULL; // No loop-invariant inputs
344
345
346 int n_op = n->Opcode();
347
348 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
349 if( n_op == Op_LShiftI ) {
350 // Scale is loop invariant
351 Node *scale = n->in(2);
352 Node *scale_ctrl = get_ctrl(scale);
353 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
354 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
355 return NULL;
356 const TypeInt *scale_t = scale->bottom_type()->isa_int();
357 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
358 return NULL; // Dont bother with byte/short masking
359 // Add must vary with loop (else shift would be loop-invariant)
360 Node *add = n->in(1);
361 Node *add_ctrl = get_ctrl(add);
362 IdealLoopTree *add_loop = get_loop(add_ctrl);
363 //assert( n_loop == add_loop, "" );
364 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
365
366 // Convert I-V into I+ (0-V); same for V-I
367 if( add->Opcode() == Op_SubI &&
368 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
369 Node *zero = _igvn.intcon(0);
370 set_ctrl(zero, C->root());
371 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
372 register_new_node( neg, get_ctrl(add->in(2) ) );
373 add = new AddINode( add->in(1), neg );
374 register_new_node( add, add_ctrl );
375 }
376 if( add->Opcode() != Op_AddI ) return NULL;
377 // See if one add input is loop invariant
378 Node *add_var = add->in(1);
379 Node *add_var_ctrl = get_ctrl(add_var);
380 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
381 Node *add_invar = add->in(2);
382 Node *add_invar_ctrl = get_ctrl(add_invar);
383 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
384 if( add_var_loop == n_loop ) {
385 } else if( add_invar_loop == n_loop ) {
386 // Swap to find the invariant part
387 add_invar = add_var;
388 add_invar_ctrl = add_var_ctrl;
389 add_invar_loop = add_var_loop;
390 add_var = add->in(2);
391 Node *add_var_ctrl = get_ctrl(add_var);
392 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
393 } else // Else neither input is loop invariant
394 return NULL;
395 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
396 return NULL; // No invariant part of the add?
397
398 // Yes! Reshape address expression!
399 Node *inv_scale = new LShiftINode( add_invar, scale );
400 Node *inv_scale_ctrl =
401 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
402 add_invar_ctrl : scale_ctrl;
403 register_new_node( inv_scale, inv_scale_ctrl );
404 Node *var_scale = new LShiftINode( add_var, scale );
405 register_new_node( var_scale, n_ctrl );
406 Node *var_add = new AddINode( var_scale, inv_scale );
407 register_new_node( var_add, n_ctrl );
408 _igvn.replace_node( n, var_add );
409 return var_add;
410 }
411
412 // Replace (I+V) with (V+I)
413 if( n_op == Op_AddI ||
414 n_op == Op_AddL ||
415 n_op == Op_AddF ||
416 n_op == Op_AddD ||
417 n_op == Op_MulI ||
418 n_op == Op_MulL ||
419 n_op == Op_MulF ||
420 n_op == Op_MulD ) {
421 if( n2_loop == n_loop ) {
422 assert( n1_loop != n_loop, "" );
423 n->swap_edges(1, 2);
424 }
425 }
426
427 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
428 // but not if I2 is a constant.
429 if( n_op == Op_AddP ) {
430 if( n2_loop == n_loop && n3_loop != n_loop ) {
431 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
432 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
433 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
434 IdealLoopTree *n22loop = get_loop( n22_ctrl );
435 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
436 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
437 n23_loop == n_loop ) {
438 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
439 // Stuff new AddP in the loop preheader
440 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
441 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
442 register_new_node( add2, n_ctrl );
443 _igvn.replace_node( n, add2 );
444 return add2;
445 }
446 }
447 }
448
449 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
450 if (n2_loop != n_loop && n3_loop == n_loop) {
451 if (n->in(3)->Opcode() == Op_AddX) {
452 Node *V = n->in(3)->in(1);
453 Node *I = n->in(3)->in(2);
454 if (is_member(n_loop,get_ctrl(V))) {
455 } else {
456 Node *tmp = V; V = I; I = tmp;
457 }
458 if (!is_member(n_loop,get_ctrl(I))) {
459 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
460 // Stuff new AddP in the loop preheader
461 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
462 Node *add2 = new AddPNode(n->in(1), add1, V);
463 register_new_node(add2, n_ctrl);
464 _igvn.replace_node(n, add2);
465 return add2;
466 }
467 }
468 }
469 }
470
471 return NULL;
472 }
473
474 //------------------------------conditional_move-------------------------------
475 // Attempt to replace a Phi with a conditional move. We have some pretty
476 // strict profitability requirements. All Phis at the merge point must
477 // be converted, so we can remove the control flow. We need to limit the
478 // number of c-moves to a small handful. All code that was in the side-arms
479 // of the CFG diamond is now speculatively executed. This code has to be
480 // "cheap enough". We are pretty much limited to CFG diamonds that merge
481 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
482 Node *PhaseIdealLoop::conditional_move( Node *region ) {
483
484 assert(region->is_Region(), "sanity check");
485 if (region->req() != 3) return NULL;
486
487 // Check for CFG diamond
488 Node *lp = region->in(1);
489 Node *rp = region->in(2);
490 if (!lp || !rp) return NULL;
491 Node *lp_c = lp->in(0);
492 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
493 IfNode *iff = lp_c->as_If();
494
495 // Check for ops pinned in an arm of the diamond.
496 // Can't remove the control flow in this case
497 if (lp->outcnt() > 1) return NULL;
498 if (rp->outcnt() > 1) return NULL;
499
500 IdealLoopTree* r_loop = get_loop(region);
501 assert(r_loop == get_loop(iff), "sanity");
502 // Always convert to CMOVE if all results are used only outside this loop.
503 bool used_inside_loop = (r_loop == _ltree_root);
504
505 // Check profitability
506 int cost = 0;
507 int phis = 0;
508 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
509 Node *out = region->fast_out(i);
510 if (!out->is_Phi()) continue; // Ignore other control edges, etc
511 phis++;
512 PhiNode* phi = out->as_Phi();
513 BasicType bt = phi->type()->basic_type();
514 switch (bt) {
515 case T_DOUBLE:
516 if (C->use_cmove()) {
517 continue; //TODO: maybe we want to add some cost
518 }
519 case T_FLOAT: {
520 cost += Matcher::float_cmove_cost(); // Could be very expensive
521 break;
522 }
523 case T_LONG: {
524 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
525 }
526 case T_INT: // These all CMOV fine
527 case T_ADDRESS: { // (RawPtr)
528 cost++;
529 break;
530 }
531 case T_NARROWOOP: // Fall through
532 case T_OBJECT: { // Base oops are OK, but not derived oops
533 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
534 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
535 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
536 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
537 // have a Phi for the base here that we convert to a CMOVE all is well
538 // and good. But if the base is dead, we'll not make a CMOVE. Later
539 // the allocator will have to produce a base by creating a CMOVE of the
540 // relevant bases. This puts the allocator in the business of
541 // manufacturing expensive instructions, generally a bad plan.
542 // Just Say No to Conditionally-Moved Derived Pointers.
543 if (tp && tp->offset() != 0)
544 return NULL;
545 cost++;
546 break;
547 }
548 default:
549 return NULL; // In particular, can't do memory or I/O
550 }
551 // Add in cost any speculative ops
552 for (uint j = 1; j < region->req(); j++) {
553 Node *proj = region->in(j);
554 Node *inp = phi->in(j);
555 if (get_ctrl(inp) == proj) { // Found local op
556 cost++;
557 // Check for a chain of dependent ops; these will all become
558 // speculative in a CMOV.
559 for (uint k = 1; k < inp->req(); k++)
560 if (get_ctrl(inp->in(k)) == proj)
561 cost += ConditionalMoveLimit; // Too much speculative goo
562 }
563 }
564 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
565 // This will likely Split-If, a higher-payoff operation.
566 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
567 Node* use = phi->fast_out(k);
568 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
569 cost += ConditionalMoveLimit;
570 // Is there a use inside the loop?
571 // Note: check only basic types since CMoveP is pinned.
572 if (!used_inside_loop && is_java_primitive(bt)) {
573 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
574 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
575 used_inside_loop = true;
576 }
577 }
578 }
579 }//for
580 Node* bol = iff->in(1);
581 assert(bol->Opcode() == Op_Bool, "");
582 int cmp_op = bol->in(1)->Opcode();
583 // It is expensive to generate flags from a float compare.
584 // Avoid duplicated float compare.
585 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
586
587 float infrequent_prob = PROB_UNLIKELY_MAG(3);
588 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
589 if (used_inside_loop) {
590 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
591
592 // BlockLayoutByFrequency optimization moves infrequent branch
593 // from hot path. No point in CMOV'ing in such case (110 is used
594 // instead of 100 to take into account not exactness of float value).
595 if (BlockLayoutByFrequency) {
596 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
597 }
598 }
599 // Check for highly predictable branch. No point in CMOV'ing if
600 // we are going to predict accurately all the time.
601 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
602 else if (iff->_prob < infrequent_prob ||
603 iff->_prob > (1.0f - infrequent_prob))
604 return NULL;
605
606 // --------------
607 // Now replace all Phis with CMOV's
608 Node *cmov_ctrl = iff->in(0);
609 uint flip = (lp->Opcode() == Op_IfTrue);
610 while (1) {
611 PhiNode* phi = NULL;
612 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
613 Node *out = region->fast_out(i);
614 if (out->is_Phi()) {
615 phi = out->as_Phi();
616 break;
617 }
618 }
619 if (phi == NULL) break;
620 #ifndef PRODUCT
621 if (PrintOpto && VerifyLoopOptimizations) tty->print_cr("CMOV");
622 #endif
623 // Move speculative ops
624 for (uint j = 1; j < region->req(); j++) {
625 Node *proj = region->in(j);
626 Node *inp = phi->in(j);
627 if (get_ctrl(inp) == proj) { // Found local op
628 #ifndef PRODUCT
629 if (PrintOpto && VerifyLoopOptimizations) {
630 tty->print(" speculate: ");
631 inp->dump();
632 }
633 #endif
634 set_ctrl(inp, cmov_ctrl);
635 }
636 }
637 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
638 register_new_node( cmov, cmov_ctrl );
639 _igvn.replace_node( phi, cmov );
640 #ifndef PRODUCT
641 if (TraceLoopOpts) {
642 tty->print("CMOV ");
643 r_loop->dump_head();
644 if (Verbose) {
645 bol->in(1)->dump(1);
646 cmov->dump(1);
647 }
648 }
649 if (VerifyLoopOptimizations) verify();
650 #endif
651 }
652
653 // The useless CFG diamond will fold up later; see the optimization in
654 // RegionNode::Ideal.
655 _igvn._worklist.push(region);
656
657 return iff->in(1);
658 }
659
660 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
661 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
662 Node* u = m->fast_out(i);
663 if (u->is_CFG()) {
664 if (u->Opcode() == Op_NeverBranch) {
665 u = ((NeverBranchNode*)u)->proj_out(0);
666 enqueue_cfg_uses(u, wq);
667 } else {
668 wq.push(u);
669 }
670 }
671 }
672 }
673
674 // Try moving a store out of a loop, right before the loop
675 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
676 // Store has to be first in the loop body
677 IdealLoopTree *n_loop = get_loop(n_ctrl);
678 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
679 Node* address = n->in(MemNode::Address);
680 Node* value = n->in(MemNode::ValueIn);
681 Node* mem = n->in(MemNode::Memory);
682 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
683 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
684
685 // - address and value must be loop invariant
686 // - memory must be a memory Phi for the loop
687 // - Store must be the only store on this memory slice in the
688 // loop: if there's another store following this one then value
689 // written at iteration i by the second store could be overwritten
690 // at iteration i+n by the first store: it's not safe to move the
691 // first store out of the loop
692 // - nothing must observe the memory Phi: it guarantees no read
693 // before the store, we are also guaranteed the store post
694 // dominates the loop head (ignoring a possible early
695 // exit). Otherwise there would be extra Phi involved between the
696 // loop's Phi and the store.
697 // - there must be no early exit from the loop before the Store
698 // (such an exit most of the time would be an extra use of the
699 // memory Phi but sometimes is a bottom memory Phi that takes the
700 // store as input).
701
702 if (!n_loop->is_member(address_loop) &&
703 !n_loop->is_member(value_loop) &&
704 mem->is_Phi() && mem->in(0) == n_loop->_head &&
705 mem->outcnt() == 1 &&
706 mem->in(LoopNode::LoopBackControl) == n) {
707
708 assert(n_loop->_tail != NULL, "need a tail");
709 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
710
711 // Verify that there's no early exit of the loop before the store.
712 bool ctrl_ok = false;
713 {
714 // Follow control from loop head until n, we exit the loop or
715 // we reach the tail
716 ResourceMark rm;
717 Unique_Node_List wq;
718 wq.push(n_loop->_head);
719
720 for (uint next = 0; next < wq.size(); ++next) {
721 Node *m = wq.at(next);
722 if (m == n->in(0)) {
723 ctrl_ok = true;
724 continue;
725 }
726 assert(!has_ctrl(m), "should be CFG");
727 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
728 ctrl_ok = false;
729 break;
730 }
731 enqueue_cfg_uses(m, wq);
732 if (wq.size() > 10) {
733 ctrl_ok = false;
734 break;
735 }
736 }
737 }
738 if (ctrl_ok) {
739 // move the Store
740 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
741 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
742 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
743 // Disconnect the phi now. An empty phi can confuse other
744 // optimizations in this pass of loop opts.
745 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
746 n_loop->_body.yank(mem);
747
748 IdealLoopTree* new_loop = get_loop(n->in(0));
749 set_ctrl_and_loop(n, n->in(0));
750
751 return n;
752 }
753 }
754 }
755 return NULL;
756 }
757
758 // Try moving a store out of a loop, right after the loop
759 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
760 if (n->is_Store() && n->in(0) != NULL) {
761 Node *n_ctrl = get_ctrl(n);
762 IdealLoopTree *n_loop = get_loop(n_ctrl);
763 // Store must be in a loop
764 if (n_loop != _ltree_root && !n_loop->_irreducible) {
765 Node* address = n->in(MemNode::Address);
766 Node* value = n->in(MemNode::ValueIn);
767 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
768 // address must be loop invariant
769 if (!n_loop->is_member(address_loop)) {
770 // Store must be last on this memory slice in the loop and
771 // nothing in the loop must observe it
772 Node* phi = NULL;
773 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
774 Node* u = n->fast_out(i);
775 if (has_ctrl(u)) { // control use?
776 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
777 if (!n_loop->is_member(u_loop)) {
778 continue;
779 }
780 if (u->is_Phi() && u->in(0) == n_loop->_head) {
781 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
782 // multiple phis on the same slice are possible
783 if (phi != NULL) {
784 return;
785 }
786 phi = u;
787 continue;
788 }
789 }
790 return;
791 }
792 if (phi != NULL) {
793 // Nothing in the loop before the store (next iteration)
794 // must observe the stored value
795 bool mem_ok = true;
796 {
797 ResourceMark rm;
798 Unique_Node_List wq;
799 wq.push(phi);
800 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
801 Node *m = wq.at(next);
802 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
803 Node* u = m->fast_out(i);
804 if (u->is_Store() || u->is_Phi()) {
805 if (u != n) {
806 wq.push(u);
807 mem_ok = (wq.size() <= 10);
808 }
809 } else {
810 mem_ok = false;
811 break;
812 }
813 }
814 }
815 }
816 if (mem_ok) {
817 // Move the Store out of the loop creating clones along
818 // all paths out of the loop that observe the stored value
819 _igvn.rehash_node_delayed(phi);
820 int count = phi->replace_edge(n, n->in(MemNode::Memory));
821 assert(count > 0, "inconsistent phi");
822 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
823 Node* u = n->fast_out(i);
824 Node* c = get_ctrl(u);
825
826 if (u->is_Phi()) {
827 c = u->in(0)->in(u->find_edge(n));
828 }
829 IdealLoopTree *u_loop = get_loop(c);
830 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
831 while(true) {
832 Node* next_c = find_non_split_ctrl(idom(c));
833 if (n_loop->is_member(get_loop(next_c))) {
834 break;
835 }
836 c = next_c;
837 }
838
839 Node* st = n->clone();
840 st->set_req(0, c);
841 _igvn.register_new_node_with_optimizer(st);
842
843 set_ctrl(st, c);
844 IdealLoopTree* new_loop = get_loop(c);
845 assert(new_loop != n_loop, "should be moved out of loop");
846 if (new_loop->_child == NULL) new_loop->_body.push(st);
847
848 _igvn.replace_input_of(u, u->find_edge(n), st);
849 --imax;
850 --i;
851 }
852
853
854 assert(n->outcnt() == 0, "all uses should be gone");
855 _igvn.replace_input_of(n, MemNode::Memory, C->top());
856 // Disconnect the phi now. An empty phi can confuse other
857 // optimizations in this pass of loop opts..
858 if (phi->in(LoopNode::LoopBackControl) == phi) {
859 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
860 n_loop->_body.yank(phi);
861 }
862 }
863 }
864 }
865 }
866 }
867 }
868
869 //------------------------------split_if_with_blocks_pre-----------------------
870 // Do the real work in a non-recursive function. Data nodes want to be
871 // cloned in the pre-order so they can feed each other nicely.
872 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
873 // Cloning these guys is unlikely to win
874 int n_op = n->Opcode();
875 if( n_op == Op_MergeMem ) return n;
876 if( n->is_Proj() ) return n;
877 // Do not clone-up CmpFXXX variations, as these are always
878 // followed by a CmpI
879 if( n->is_Cmp() ) return n;
880 // Attempt to use a conditional move instead of a phi/branch
881 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
882 Node *cmov = conditional_move( n );
883 if( cmov ) return cmov;
884 }
885 if( n->is_CFG() || n->is_LoadStore() )
886 return n;
887 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
888 n_op == Op_Opaque2 ) {
889 if( !C->major_progress() ) // If chance of no more loop opts...
890 _igvn._worklist.push(n); // maybe we'll remove them
891 return n;
892 }
893
894 if( n->is_Con() ) return n; // No cloning for Con nodes
895
896 Node *n_ctrl = get_ctrl(n);
897 if( !n_ctrl ) return n; // Dead node
898
899 Node* res = try_move_store_before_loop(n, n_ctrl);
900 if (res != NULL) {
901 return n;
902 }
903
904 // Attempt to remix address expressions for loop invariants
905 Node *m = remix_address_expressions( n );
906 if( m ) return m;
907
908 // Determine if the Node has inputs from some local Phi.
909 // Returns the block to clone thru.
910 Node *n_blk = has_local_phi_input( n );
911 if( !n_blk ) return n;
912
913 // Do not clone the trip counter through on a CountedLoop
914 // (messes up the canonical shape).
915 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
916
917 // Check for having no control input; not pinned. Allow
918 // dominating control.
919 if (n->in(0)) {
920 Node *dom = idom(n_blk);
921 if (dom_lca(n->in(0), dom) != n->in(0)) {
922 return n;
923 }
924 }
925 // Policy: when is it profitable. You must get more wins than
926 // policy before it is considered profitable. Policy is usually 0,
927 // so 1 win is considered profitable. Big merges will require big
928 // cloning, so get a larger policy.
929 int policy = n_blk->req() >> 2;
930
931 // If the loop is a candidate for range check elimination,
932 // delay splitting through it's phi until a later loop optimization
933 if (n_blk->is_CountedLoop()) {
934 IdealLoopTree *lp = get_loop(n_blk);
935 if (lp && lp->_rce_candidate) {
936 return n;
937 }
938 }
939
940 // Use same limit as split_if_with_blocks_post
941 if( C->live_nodes() > 35000 ) return n; // Method too big
942
943 // Split 'n' through the merge point if it is profitable
944 Node *phi = split_thru_phi( n, n_blk, policy );
945 if (!phi) return n;
946
947 // Found a Phi to split thru!
948 // Replace 'n' with the new phi
949 _igvn.replace_node( n, phi );
950 // Moved a load around the loop, 'en-registering' something.
951 if (n_blk->is_Loop() && n->is_Load() &&
952 !phi->in(LoopNode::LoopBackControl)->is_Load())
953 C->set_major_progress();
954
955 return phi;
956 }
957
958 static bool merge_point_too_heavy(Compile* C, Node* region) {
959 // Bail out if the region and its phis have too many users.
960 int weight = 0;
961 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
962 weight += region->fast_out(i)->outcnt();
963 }
964 int nodes_left = C->max_node_limit() - C->live_nodes();
965 if (weight * 8 > nodes_left) {
966 #ifndef PRODUCT
967 if (PrintOpto)
968 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
969 #endif
970 return true;
971 } else {
972 return false;
973 }
974 }
975
976 static bool merge_point_safe(Node* region) {
977 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
978 // having a PhiNode input. This sidesteps the dangerous case where the split
979 // ConvI2LNode may become TOP if the input Value() does not
980 // overlap the ConvI2L range, leaving a node which may not dominate its
981 // uses.
982 // A better fix for this problem can be found in the BugTraq entry, but
983 // expediency for Mantis demands this hack.
984 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
985 // split_if_with_blocks from splitting a block because we could not move around
986 // the FastLockNode.
987 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
988 Node* n = region->fast_out(i);
989 if (n->is_Phi()) {
990 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
991 Node* m = n->fast_out(j);
992 if (m->is_FastLock())
993 return false;
994 #ifdef _LP64
995 if (m->Opcode() == Op_ConvI2L)
996 return false;
997 #endif
998 }
999 }
1000 }
1001 return true;
1002 }
1003
1004
1005 //------------------------------place_near_use---------------------------------
1006 // Place some computation next to use but not inside inner loops.
1007 // For inner loop uses move it to the preheader area.
1008 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1009 IdealLoopTree *u_loop = get_loop( useblock );
1010 return (u_loop->_irreducible || u_loop->_child)
1011 ? useblock
1012 : u_loop->_head->in(LoopNode::EntryControl);
1013 }
1014
1015
1016 //------------------------------split_if_with_blocks_post----------------------
1017 // Do the real work in a non-recursive function. CFG hackery wants to be
1018 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1019 // info.
1020 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1021
1022 // Cloning Cmp through Phi's involves the split-if transform.
1023 // FastLock is not used by an If
1024 if( n->is_Cmp() && !n->is_FastLock() ) {
1025 if( C->live_nodes() > 35000 ) return; // Method too big
1026
1027 // Do not do 'split-if' if irreducible loops are present.
1028 if( _has_irreducible_loops )
1029 return;
1030
1031 Node *n_ctrl = get_ctrl(n);
1032 // Determine if the Node has inputs from some local Phi.
1033 // Returns the block to clone thru.
1034 Node *n_blk = has_local_phi_input( n );
1035 if( n_blk != n_ctrl ) return;
1036
1037 if( merge_point_too_heavy(C, n_ctrl) )
1038 return;
1039
1040 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1041 Node *bol = n->unique_out();
1042 assert( bol->is_Bool(), "expect a bool here" );
1043 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1044 Node *iff = bol->unique_out();
1045
1046 // Check some safety conditions
1047 if( iff->is_If() ) { // Classic split-if?
1048 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1049 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1050 // Can't split CMove with different control edge.
1051 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1052 if( get_ctrl(iff->in(2)) == n_ctrl ||
1053 get_ctrl(iff->in(3)) == n_ctrl )
1054 return; // Inputs not yet split-up
1055 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1056 return; // Loop-invar test gates loop-varying CMOVE
1057 }
1058 } else {
1059 return; // some other kind of node, such as an Allocate
1060 }
1061
1062 // Do not do 'split-if' if some paths are dead. First do dead code
1063 // elimination and then see if its still profitable.
1064 for( uint i = 1; i < n_ctrl->req(); i++ )
1065 if( n_ctrl->in(i) == C->top() )
1066 return;
1067
1068 // When is split-if profitable? Every 'win' on means some control flow
1069 // goes dead, so it's almost always a win.
1070 int policy = 0;
1071 // If trying to do a 'Split-If' at the loop head, it is only
1072 // profitable if the cmp folds up on BOTH paths. Otherwise we
1073 // risk peeling a loop forever.
1074
1075 // CNC - Disabled for now. Requires careful handling of loop
1076 // body selection for the cloned code. Also, make sure we check
1077 // for any input path not being in the same loop as n_ctrl. For
1078 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1079 // because the alternative loop entry points won't be converted
1080 // into LoopNodes.
1081 IdealLoopTree *n_loop = get_loop(n_ctrl);
1082 for( uint j = 1; j < n_ctrl->req(); j++ )
1083 if( get_loop(n_ctrl->in(j)) != n_loop )
1084 return;
1085
1086 // Check for safety of the merge point.
1087 if( !merge_point_safe(n_ctrl) ) {
1088 return;
1089 }
1090
1091 // Split compare 'n' through the merge point if it is profitable
1092 Node *phi = split_thru_phi( n, n_ctrl, policy );
1093 if( !phi ) return;
1094
1095 // Found a Phi to split thru!
1096 // Replace 'n' with the new phi
1097 _igvn.replace_node( n, phi );
1098
1099 // Now split the bool up thru the phi
1100 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1101 guarantee(bolphi != NULL, "null boolean phi node");
1102
1103 _igvn.replace_node( bol, bolphi );
1104 assert( iff->in(1) == bolphi, "" );
1105
1106 if( bolphi->Value(&_igvn)->singleton() )
1107 return;
1108
1109 // Conditional-move? Must split up now
1110 if( !iff->is_If() ) {
1111 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1112 _igvn.replace_node( iff, cmovphi );
1113 return;
1114 }
1115
1116 // Now split the IF
1117 do_split_if( iff );
1118 return;
1119 }
1120
1121 // Check for an IF ready to split; one that has its
1122 // condition codes input coming from a Phi at the block start.
1123 int n_op = n->Opcode();
1124
1125 // Check for an IF being dominated by another IF same test
1126 if (n_op == Op_If) {
1127 Node *bol = n->in(1);
1128 uint max = bol->outcnt();
1129 // Check for same test used more than once?
1130 if (max > 1 && bol->is_Bool()) {
1131 // Search up IDOMs to see if this IF is dominated.
1132 Node *cutoff = get_ctrl(bol);
1133
1134 // Now search up IDOMs till cutoff, looking for a dominating test
1135 Node *prevdom = n;
1136 Node *dom = idom(prevdom);
1137 while (dom != cutoff) {
1138 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1139 // Replace the dominated test with an obvious true or false.
1140 // Place it on the IGVN worklist for later cleanup.
1141 C->set_major_progress();
1142 dominated_by(prevdom, n, false, true);
1143 #ifndef PRODUCT
1144 if( VerifyLoopOptimizations ) verify();
1145 #endif
1146 return;
1147 }
1148 prevdom = dom;
1149 dom = idom(prevdom);
1150 }
1151 }
1152 }
1153
1154 // See if a shared loop-varying computation has no loop-varying uses.
1155 // Happens if something is only used for JVM state in uncommon trap exits,
1156 // like various versions of induction variable+offset. Clone the
1157 // computation per usage to allow it to sink out of the loop.
1158 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1159 Node *n_ctrl = get_ctrl(n);
1160 IdealLoopTree *n_loop = get_loop(n_ctrl);
1161 if( n_loop != _ltree_root ) {
1162 DUIterator_Fast imax, i = n->fast_outs(imax);
1163 for (; i < imax; i++) {
1164 Node* u = n->fast_out(i);
1165 if( !has_ctrl(u) ) break; // Found control user
1166 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1167 if( u_loop == n_loop ) break; // Found loop-varying use
1168 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1169 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1170 }
1171 bool did_break = (i < imax); // Did we break out of the previous loop?
1172 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1173 Node *late_load_ctrl = NULL;
1174 if (n->is_Load()) {
1175 // If n is a load, get and save the result from get_late_ctrl(),
1176 // to be later used in calculating the control for n's clones.
1177 clear_dom_lca_tags();
1178 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1179 }
1180 // If n is a load, and the late control is the same as the current
1181 // control, then the cloning of n is a pointless exercise, because
1182 // GVN will ensure that we end up where we started.
1183 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1184 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1185 Node *u = n->last_out(j); // Clone private computation per use
1186 _igvn.rehash_node_delayed(u);
1187 Node *x = n->clone(); // Clone computation
1188 Node *x_ctrl = NULL;
1189 if( u->is_Phi() ) {
1190 // Replace all uses of normal nodes. Replace Phi uses
1191 // individually, so the separate Nodes can sink down
1192 // different paths.
1193 uint k = 1;
1194 while( u->in(k) != n ) k++;
1195 u->set_req( k, x );
1196 // x goes next to Phi input path
1197 x_ctrl = u->in(0)->in(k);
1198 --j;
1199 } else { // Normal use
1200 // Replace all uses
1201 for( uint k = 0; k < u->req(); k++ ) {
1202 if( u->in(k) == n ) {
1203 u->set_req( k, x );
1204 --j;
1205 }
1206 }
1207 x_ctrl = get_ctrl(u);
1208 }
1209
1210 // Find control for 'x' next to use but not inside inner loops.
1211 // For inner loop uses get the preheader area.
1212 x_ctrl = place_near_use(x_ctrl);
1213
1214 if (n->is_Load()) {
1215 // For loads, add a control edge to a CFG node outside of the loop
1216 // to force them to not combine and return back inside the loop
1217 // during GVN optimization (4641526).
1218 //
1219 // Because we are setting the actual control input, factor in
1220 // the result from get_late_ctrl() so we respect any
1221 // anti-dependences. (6233005).
1222 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1223
1224 // Don't allow the control input to be a CFG splitting node.
1225 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1226 // should only have IfTrueNode and IfFalseNode (4985384).
1227 x_ctrl = find_non_split_ctrl(x_ctrl);
1228 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1229
1230 x->set_req(0, x_ctrl);
1231 }
1232 register_new_node(x, x_ctrl);
1233
1234 // Some institutional knowledge is needed here: 'x' is
1235 // yanked because if the optimizer runs GVN on it all the
1236 // cloned x's will common up and undo this optimization and
1237 // be forced back in the loop. This is annoying because it
1238 // makes +VerifyOpto report false-positives on progress. I
1239 // tried setting control edges on the x's to force them to
1240 // not combine, but the matching gets worried when it tries
1241 // to fold a StoreP and an AddP together (as part of an
1242 // address expression) and the AddP and StoreP have
1243 // different controls.
1244 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1245 }
1246 _igvn.remove_dead_node(n);
1247 }
1248 }
1249 }
1250 }
1251
1252 try_move_store_after_loop(n);
1253
1254 // Check for Opaque2's who's loop has disappeared - who's input is in the
1255 // same loop nest as their output. Remove 'em, they are no longer useful.
1256 if( n_op == Op_Opaque2 &&
1257 n->in(1) != NULL &&
1258 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1259 _igvn.replace_node( n, n->in(1) );
1260 }
1261 }
1262
1263 //------------------------------split_if_with_blocks---------------------------
1264 // Check for aggressive application of 'split-if' optimization,
1265 // using basic block level info.
1266 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1267 Node *n = C->root();
1268 visited.set(n->_idx); // first, mark node as visited
1269 // Do pre-visit work for root
1270 n = split_if_with_blocks_pre( n );
1271 uint cnt = n->outcnt();
1272 uint i = 0;
1273 while (true) {
1274 // Visit all children
1275 if (i < cnt) {
1276 Node* use = n->raw_out(i);
1277 ++i;
1278 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1279 // Now do pre-visit work for this use
1280 use = split_if_with_blocks_pre( use );
1281 nstack.push(n, i); // Save parent and next use's index.
1282 n = use; // Process all children of current use.
1283 cnt = use->outcnt();
1284 i = 0;
1285 }
1286 }
1287 else {
1288 // All of n's children have been processed, complete post-processing.
1289 if (cnt != 0 && !n->is_Con()) {
1290 assert(has_node(n), "no dead nodes");
1291 split_if_with_blocks_post( n );
1292 }
1293 if (nstack.is_empty()) {
1294 // Finished all nodes on stack.
1295 break;
1296 }
1297 // Get saved parent node and next use's index. Visit the rest of uses.
1298 n = nstack.node();
1299 cnt = n->outcnt();
1300 i = nstack.index();
1301 nstack.pop();
1302 }
1303 }
1304 }
1305
1306
1307 //=============================================================================
1308 //
1309 // C L O N E A L O O P B O D Y
1310 //
1311
1312 //------------------------------clone_iff--------------------------------------
1313 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1314 // "Nearly" because all Nodes have been cloned from the original in the loop,
1315 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1316 // through the Phi recursively, and return a Bool.
1317 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1318
1319 // Convert this Phi into a Phi merging Bools
1320 uint i;
1321 for( i = 1; i < phi->req(); i++ ) {
1322 Node *b = phi->in(i);
1323 if( b->is_Phi() ) {
1324 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1325 } else {
1326 assert( b->is_Bool(), "" );
1327 }
1328 }
1329
1330 Node *sample_bool = phi->in(1);
1331 Node *sample_cmp = sample_bool->in(1);
1332
1333 // Make Phis to merge the Cmp's inputs.
1334 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1335 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1336 for( i = 1; i < phi->req(); i++ ) {
1337 Node *n1 = phi->in(i)->in(1)->in(1);
1338 Node *n2 = phi->in(i)->in(1)->in(2);
1339 phi1->set_req( i, n1 );
1340 phi2->set_req( i, n2 );
1341 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1342 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1343 }
1344 // See if these Phis have been made before.
1345 // Register with optimizer
1346 Node *hit1 = _igvn.hash_find_insert(phi1);
1347 if( hit1 ) { // Hit, toss just made Phi
1348 _igvn.remove_dead_node(phi1); // Remove new phi
1349 assert( hit1->is_Phi(), "" );
1350 phi1 = (PhiNode*)hit1; // Use existing phi
1351 } else { // Miss
1352 _igvn.register_new_node_with_optimizer(phi1);
1353 }
1354 Node *hit2 = _igvn.hash_find_insert(phi2);
1355 if( hit2 ) { // Hit, toss just made Phi
1356 _igvn.remove_dead_node(phi2); // Remove new phi
1357 assert( hit2->is_Phi(), "" );
1358 phi2 = (PhiNode*)hit2; // Use existing phi
1359 } else { // Miss
1360 _igvn.register_new_node_with_optimizer(phi2);
1361 }
1362 // Register Phis with loop/block info
1363 set_ctrl(phi1, phi->in(0));
1364 set_ctrl(phi2, phi->in(0));
1365 // Make a new Cmp
1366 Node *cmp = sample_cmp->clone();
1367 cmp->set_req( 1, phi1 );
1368 cmp->set_req( 2, phi2 );
1369 _igvn.register_new_node_with_optimizer(cmp);
1370 set_ctrl(cmp, phi->in(0));
1371
1372 // Make a new Bool
1373 Node *b = sample_bool->clone();
1374 b->set_req(1,cmp);
1375 _igvn.register_new_node_with_optimizer(b);
1376 set_ctrl(b, phi->in(0));
1377
1378 assert( b->is_Bool(), "" );
1379 return (BoolNode*)b;
1380 }
1381
1382 //------------------------------clone_bool-------------------------------------
1383 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1384 // "Nearly" because all Nodes have been cloned from the original in the loop,
1385 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1386 // through the Phi recursively, and return a Bool.
1387 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1388 uint i;
1389 // Convert this Phi into a Phi merging Bools
1390 for( i = 1; i < phi->req(); i++ ) {
1391 Node *b = phi->in(i);
1392 if( b->is_Phi() ) {
1393 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1394 } else {
1395 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1396 }
1397 }
1398
1399 Node *sample_cmp = phi->in(1);
1400
1401 // Make Phis to merge the Cmp's inputs.
1402 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1403 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1404 for( uint j = 1; j < phi->req(); j++ ) {
1405 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1406 Node *n1, *n2;
1407 if( cmp_top->is_Cmp() ) {
1408 n1 = cmp_top->in(1);
1409 n2 = cmp_top->in(2);
1410 } else {
1411 n1 = n2 = cmp_top;
1412 }
1413 phi1->set_req( j, n1 );
1414 phi2->set_req( j, n2 );
1415 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1416 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1417 }
1418
1419 // See if these Phis have been made before.
1420 // Register with optimizer
1421 Node *hit1 = _igvn.hash_find_insert(phi1);
1422 if( hit1 ) { // Hit, toss just made Phi
1423 _igvn.remove_dead_node(phi1); // Remove new phi
1424 assert( hit1->is_Phi(), "" );
1425 phi1 = (PhiNode*)hit1; // Use existing phi
1426 } else { // Miss
1427 _igvn.register_new_node_with_optimizer(phi1);
1428 }
1429 Node *hit2 = _igvn.hash_find_insert(phi2);
1430 if( hit2 ) { // Hit, toss just made Phi
1431 _igvn.remove_dead_node(phi2); // Remove new phi
1432 assert( hit2->is_Phi(), "" );
1433 phi2 = (PhiNode*)hit2; // Use existing phi
1434 } else { // Miss
1435 _igvn.register_new_node_with_optimizer(phi2);
1436 }
1437 // Register Phis with loop/block info
1438 set_ctrl(phi1, phi->in(0));
1439 set_ctrl(phi2, phi->in(0));
1440 // Make a new Cmp
1441 Node *cmp = sample_cmp->clone();
1442 cmp->set_req( 1, phi1 );
1443 cmp->set_req( 2, phi2 );
1444 _igvn.register_new_node_with_optimizer(cmp);
1445 set_ctrl(cmp, phi->in(0));
1446
1447 assert( cmp->is_Cmp(), "" );
1448 return (CmpNode*)cmp;
1449 }
1450
1451 //------------------------------sink_use---------------------------------------
1452 // If 'use' was in the loop-exit block, it now needs to be sunk
1453 // below the post-loop merge point.
1454 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1455 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1456 set_ctrl(use, post_loop);
1457 for (DUIterator j = use->outs(); use->has_out(j); j++)
1458 sink_use(use->out(j), post_loop);
1459 }
1460 }
1461
1462 //------------------------------clone_loop-------------------------------------
1463 //
1464 // C L O N E A L O O P B O D Y
1465 //
1466 // This is the basic building block of the loop optimizations. It clones an
1467 // entire loop body. It makes an old_new loop body mapping; with this mapping
1468 // you can find the new-loop equivalent to an old-loop node. All new-loop
1469 // nodes are exactly equal to their old-loop counterparts, all edges are the
1470 // same. All exits from the old-loop now have a RegionNode that merges the
1471 // equivalent new-loop path. This is true even for the normal "loop-exit"
1472 // condition. All uses of loop-invariant old-loop values now come from (one
1473 // or more) Phis that merge their new-loop equivalents.
1474 //
1475 // This operation leaves the graph in an illegal state: there are two valid
1476 // control edges coming from the loop pre-header to both loop bodies. I'll
1477 // definitely have to hack the graph after running this transform.
1478 //
1479 // From this building block I will further edit edges to perform loop peeling
1480 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1481 //
1482 // Parameter side_by_size_idom:
1483 // When side_by_size_idom is NULL, the dominator tree is constructed for
1484 // the clone loop to dominate the original. Used in construction of
1485 // pre-main-post loop sequence.
1486 // When nonnull, the clone and original are side-by-side, both are
1487 // dominated by the side_by_side_idom node. Used in construction of
1488 // unswitched loops.
1489 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1490 Node* side_by_side_idom) {
1491
1492 #ifndef PRODUCT
1493 if (C->do_vector_loop() && PrintOpto) {
1494 const char* mname = C->method()->name()->as_quoted_ascii();
1495 if (mname != NULL) {
1496 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1497 }
1498 }
1499 #endif
1500
1501 CloneMap& cm = C->clone_map();
1502 Dict* dict = cm.dict();
1503 if (C->do_vector_loop()) {
1504 cm.set_clone_idx(cm.max_gen()+1);
1505 #ifndef PRODUCT
1506 if (PrintOpto) {
1507 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1508 loop->dump_head();
1509 }
1510 #endif
1511 }
1512
1513 // Step 1: Clone the loop body. Make the old->new mapping.
1514 uint i;
1515 for( i = 0; i < loop->_body.size(); i++ ) {
1516 Node *old = loop->_body.at(i);
1517 Node *nnn = old->clone();
1518 old_new.map( old->_idx, nnn );
1519 if (C->do_vector_loop()) {
1520 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1521 }
1522 _igvn.register_new_node_with_optimizer(nnn);
1523 }
1524
1525
1526 // Step 2: Fix the edges in the new body. If the old input is outside the
1527 // loop use it. If the old input is INside the loop, use the corresponding
1528 // new node instead.
1529 for( i = 0; i < loop->_body.size(); i++ ) {
1530 Node *old = loop->_body.at(i);
1531 Node *nnn = old_new[old->_idx];
1532 // Fix CFG/Loop controlling the new node
1533 if (has_ctrl(old)) {
1534 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1535 } else {
1536 set_loop(nnn, loop->_parent);
1537 if (old->outcnt() > 0) {
1538 set_idom( nnn, old_new[idom(old)->_idx], dd );
1539 }
1540 }
1541 // Correct edges to the new node
1542 for( uint j = 0; j < nnn->req(); j++ ) {
1543 Node *n = nnn->in(j);
1544 if( n ) {
1545 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1546 if( loop->is_member( old_in_loop ) )
1547 nnn->set_req(j, old_new[n->_idx]);
1548 }
1549 }
1550 _igvn.hash_find_insert(nnn);
1551 }
1552 Node *newhead = old_new[loop->_head->_idx];
1553 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1554
1555
1556 // Step 3: Now fix control uses. Loop varying control uses have already
1557 // been fixed up (as part of all input edges in Step 2). Loop invariant
1558 // control uses must be either an IfFalse or an IfTrue. Make a merge
1559 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1560 // refer to this.
1561 ResourceArea *area = Thread::current()->resource_area();
1562 Node_List worklist(area);
1563 uint new_counter = C->unique();
1564 for( i = 0; i < loop->_body.size(); i++ ) {
1565 Node* old = loop->_body.at(i);
1566 if( !old->is_CFG() ) continue;
1567 Node* nnn = old_new[old->_idx];
1568
1569 // Copy uses to a worklist, so I can munge the def-use info
1570 // with impunity.
1571 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1572 worklist.push(old->fast_out(j));
1573
1574 while( worklist.size() ) { // Visit all uses
1575 Node *use = worklist.pop();
1576 if (!has_node(use)) continue; // Ignore dead nodes
1577 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1578 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1579 // Both OLD and USE are CFG nodes here.
1580 assert( use->is_Proj(), "" );
1581
1582 // Clone the loop exit control projection
1583 Node *newuse = use->clone();
1584 if (C->do_vector_loop()) {
1585 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1586 }
1587 newuse->set_req(0,nnn);
1588 _igvn.register_new_node_with_optimizer(newuse);
1589 set_loop(newuse, use_loop);
1590 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1591
1592 // We need a Region to merge the exit from the peeled body and the
1593 // exit from the old loop body.
1594 RegionNode *r = new RegionNode(3);
1595 // Map the old use to the new merge point
1596 old_new.map( use->_idx, r );
1597 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1598 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1599
1600 // The original user of 'use' uses 'r' instead.
1601 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1602 Node* useuse = use->last_out(l);
1603 _igvn.rehash_node_delayed(useuse);
1604 uint uses_found = 0;
1605 if( useuse->in(0) == use ) {
1606 useuse->set_req(0, r);
1607 uses_found++;
1608 if( useuse->is_CFG() ) {
1609 assert( dom_depth(useuse) > dd_r, "" );
1610 set_idom(useuse, r, dom_depth(useuse));
1611 }
1612 }
1613 for( uint k = 1; k < useuse->req(); k++ ) {
1614 if( useuse->in(k) == use ) {
1615 useuse->set_req(k, r);
1616 uses_found++;
1617 }
1618 }
1619 l -= uses_found; // we deleted 1 or more copies of this edge
1620 }
1621
1622 // Now finish up 'r'
1623 r->set_req( 1, newuse );
1624 r->set_req( 2, use );
1625 _igvn.register_new_node_with_optimizer(r);
1626 set_loop(r, use_loop);
1627 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1628 } // End of if a loop-exit test
1629 }
1630 }
1631
1632 // Step 4: If loop-invariant use is not control, it must be dominated by a
1633 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1634 // there if needed. Make a Phi there merging old and new used values.
1635 Node_List *split_if_set = NULL;
1636 Node_List *split_bool_set = NULL;
1637 Node_List *split_cex_set = NULL;
1638 for( i = 0; i < loop->_body.size(); i++ ) {
1639 Node* old = loop->_body.at(i);
1640 Node* nnn = old_new[old->_idx];
1641 // Copy uses to a worklist, so I can munge the def-use info
1642 // with impunity.
1643 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1644 worklist.push(old->fast_out(j));
1645
1646 while( worklist.size() ) {
1647 Node *use = worklist.pop();
1648 if (!has_node(use)) continue; // Ignore dead nodes
1649 if (use->in(0) == C->top()) continue;
1650 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1651 // Check for data-use outside of loop - at least one of OLD or USE
1652 // must not be a CFG node.
1653 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1654
1655 // If the Data use is an IF, that means we have an IF outside of the
1656 // loop that is switching on a condition that is set inside of the
1657 // loop. Happens if people set a loop-exit flag; then test the flag
1658 // in the loop to break the loop, then test is again outside of the
1659 // loop to determine which way the loop exited.
1660 // Loop predicate If node connects to Bool node through Opaque1 node.
1661 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1662 // Since this code is highly unlikely, we lazily build the worklist
1663 // of such Nodes to go split.
1664 if( !split_if_set )
1665 split_if_set = new Node_List(area);
1666 split_if_set->push(use);
1667 }
1668 if( use->is_Bool() ) {
1669 if( !split_bool_set )
1670 split_bool_set = new Node_List(area);
1671 split_bool_set->push(use);
1672 }
1673 if( use->Opcode() == Op_CreateEx ) {
1674 if( !split_cex_set )
1675 split_cex_set = new Node_List(area);
1676 split_cex_set->push(use);
1677 }
1678
1679
1680 // Get "block" use is in
1681 uint idx = 0;
1682 while( use->in(idx) != old ) idx++;
1683 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1684 assert( !loop->is_member( get_loop( prev ) ), "" );
1685 Node *cfg = prev->_idx >= new_counter
1686 ? prev->in(2)
1687 : idom(prev);
1688 if( use->is_Phi() ) // Phi use is in prior block
1689 cfg = prev->in(idx); // NOT in block of Phi itself
1690 if (cfg->is_top()) { // Use is dead?
1691 _igvn.replace_input_of(use, idx, C->top());
1692 continue;
1693 }
1694
1695 while( !loop->is_member( get_loop( cfg ) ) ) {
1696 prev = cfg;
1697 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1698 }
1699 // If the use occurs after merging several exits from the loop, then
1700 // old value must have dominated all those exits. Since the same old
1701 // value was used on all those exits we did not need a Phi at this
1702 // merge point. NOW we do need a Phi here. Each loop exit value
1703 // is now merged with the peeled body exit; each exit gets its own
1704 // private Phi and those Phis need to be merged here.
1705 Node *phi;
1706 if( prev->is_Region() ) {
1707 if( idx == 0 ) { // Updating control edge?
1708 phi = prev; // Just use existing control
1709 } else { // Else need a new Phi
1710 phi = PhiNode::make( prev, old );
1711 // Now recursively fix up the new uses of old!
1712 for( uint i = 1; i < prev->req(); i++ ) {
1713 worklist.push(phi); // Onto worklist once for each 'old' input
1714 }
1715 }
1716 } else {
1717 // Get new RegionNode merging old and new loop exits
1718 prev = old_new[prev->_idx];
1719 assert( prev, "just made this in step 7" );
1720 if( idx == 0 ) { // Updating control edge?
1721 phi = prev; // Just use existing control
1722 } else { // Else need a new Phi
1723 // Make a new Phi merging data values properly
1724 phi = PhiNode::make( prev, old );
1725 phi->set_req( 1, nnn );
1726 }
1727 }
1728 // If inserting a new Phi, check for prior hits
1729 if( idx != 0 ) {
1730 Node *hit = _igvn.hash_find_insert(phi);
1731 if( hit == NULL ) {
1732 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1733 } else { // or
1734 // Remove the new phi from the graph and use the hit
1735 _igvn.remove_dead_node(phi);
1736 phi = hit; // Use existing phi
1737 }
1738 set_ctrl(phi, prev);
1739 }
1740 // Make 'use' use the Phi instead of the old loop body exit value
1741 _igvn.replace_input_of(use, idx, phi);
1742 if( use->_idx >= new_counter ) { // If updating new phis
1743 // Not needed for correctness, but prevents a weak assert
1744 // in AddPNode from tripping (when we end up with different
1745 // base & derived Phis that will become the same after
1746 // IGVN does CSE).
1747 Node *hit = _igvn.hash_find_insert(use);
1748 if( hit ) // Go ahead and re-hash for hits.
1749 _igvn.replace_node( use, hit );
1750 }
1751
1752 // If 'use' was in the loop-exit block, it now needs to be sunk
1753 // below the post-loop merge point.
1754 sink_use( use, prev );
1755 }
1756 }
1757 }
1758
1759 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1760 // the loop uses a condition set in the loop. The original IF probably
1761 // takes control from one or more OLD Regions (which in turn get from NEW
1762 // Regions). In any case, there will be a set of Phis for each merge point
1763 // from the IF up to where the original BOOL def exists the loop.
1764 if( split_if_set ) {
1765 while( split_if_set->size() ) {
1766 Node *iff = split_if_set->pop();
1767 if( iff->in(1)->is_Phi() ) {
1768 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1769 _igvn.replace_input_of(iff, 1, b);
1770 }
1771 }
1772 }
1773 if( split_bool_set ) {
1774 while( split_bool_set->size() ) {
1775 Node *b = split_bool_set->pop();
1776 Node *phi = b->in(1);
1777 assert( phi->is_Phi(), "" );
1778 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1779 _igvn.replace_input_of(b, 1, cmp);
1780 }
1781 }
1782 if( split_cex_set ) {
1783 while( split_cex_set->size() ) {
1784 Node *b = split_cex_set->pop();
1785 assert( b->in(0)->is_Region(), "" );
1786 assert( b->in(1)->is_Phi(), "" );
1787 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1788 split_up( b, b->in(0), NULL );
1789 }
1790 }
1791
1792 }
1793
1794
1795 //---------------------- stride_of_possible_iv -------------------------------------
1796 // Looks for an iff/bool/comp with one operand of the compare
1797 // being a cycle involving an add and a phi,
1798 // with an optional truncation (left-shift followed by a right-shift)
1799 // of the add. Returns zero if not an iv.
1800 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1801 Node* trunc1 = NULL;
1802 Node* trunc2 = NULL;
1803 const TypeInt* ttype = NULL;
1804 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1805 return 0;
1806 }
1807 BoolNode* bl = iff->in(1)->as_Bool();
1808 Node* cmp = bl->in(1);
1809 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1810 return 0;
1811 }
1812 // Must have an invariant operand
1813 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1814 return 0;
1815 }
1816 Node* add2 = NULL;
1817 Node* cmp1 = cmp->in(1);
1818 if (cmp1->is_Phi()) {
1819 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1820 Node* phi = cmp1;
1821 for (uint i = 1; i < phi->req(); i++) {
1822 Node* in = phi->in(i);
1823 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1824 &trunc1, &trunc2, &ttype);
1825 if (add && add->in(1) == phi) {
1826 add2 = add->in(2);
1827 break;
1828 }
1829 }
1830 } else {
1831 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1832 Node* addtrunc = cmp1;
1833 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1834 &trunc1, &trunc2, &ttype);
1835 if (add && add->in(1)->is_Phi()) {
1836 Node* phi = add->in(1);
1837 for (uint i = 1; i < phi->req(); i++) {
1838 if (phi->in(i) == addtrunc) {
1839 add2 = add->in(2);
1840 break;
1841 }
1842 }
1843 }
1844 }
1845 if (add2 != NULL) {
1846 const TypeInt* add2t = _igvn.type(add2)->is_int();
1847 if (add2t->is_con()) {
1848 return add2t->get_con();
1849 }
1850 }
1851 return 0;
1852 }
1853
1854
1855 //---------------------- stay_in_loop -------------------------------------
1856 // Return the (unique) control output node that's in the loop (if it exists.)
1857 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1858 Node* unique = NULL;
1859 if (!n) return NULL;
1860 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1861 Node* use = n->fast_out(i);
1862 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1863 if (unique != NULL) {
1864 return NULL;
1865 }
1866 unique = use;
1867 }
1868 }
1869 return unique;
1870 }
1871
1872 //------------------------------ register_node -------------------------------------
1873 // Utility to register node "n" with PhaseIdealLoop
1874 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1875 _igvn.register_new_node_with_optimizer(n);
1876 loop->_body.push(n);
1877 if (n->is_CFG()) {
1878 set_loop(n, loop);
1879 set_idom(n, pred, ddepth);
1880 } else {
1881 set_ctrl(n, pred);
1882 }
1883 }
1884
1885 //------------------------------ proj_clone -------------------------------------
1886 // Utility to create an if-projection
1887 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1888 ProjNode* c = p->clone()->as_Proj();
1889 c->set_req(0, iff);
1890 return c;
1891 }
1892
1893 //------------------------------ short_circuit_if -------------------------------------
1894 // Force the iff control output to be the live_proj
1895 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1896 guarantee(live_proj != NULL, "null projection");
1897 int proj_con = live_proj->_con;
1898 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1899 Node *con = _igvn.intcon(proj_con);
1900 set_ctrl(con, C->root());
1901 if (iff) {
1902 iff->set_req(1, con);
1903 }
1904 return con;
1905 }
1906
1907 //------------------------------ insert_if_before_proj -------------------------------------
1908 // Insert a new if before an if projection (* - new node)
1909 //
1910 // before
1911 // if(test)
1912 // / \
1913 // v v
1914 // other-proj proj (arg)
1915 //
1916 // after
1917 // if(test)
1918 // / \
1919 // / v
1920 // | * proj-clone
1921 // v |
1922 // other-proj v
1923 // * new_if(relop(cmp[IU](left,right)))
1924 // / \
1925 // v v
1926 // * new-proj proj
1927 // (returned)
1928 //
1929 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1930 IfNode* iff = proj->in(0)->as_If();
1931 IdealLoopTree *loop = get_loop(proj);
1932 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1933 int ddepth = dom_depth(proj);
1934
1935 _igvn.rehash_node_delayed(iff);
1936 _igvn.rehash_node_delayed(proj);
1937
1938 proj->set_req(0, NULL); // temporary disconnect
1939 ProjNode* proj2 = proj_clone(proj, iff);
1940 register_node(proj2, loop, iff, ddepth);
1941
1942 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1943 register_node(cmp, loop, proj2, ddepth);
1944
1945 BoolNode* bol = new BoolNode(cmp, relop);
1946 register_node(bol, loop, proj2, ddepth);
1947
1948 IfNode* new_if = new IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1949 register_node(new_if, loop, proj2, ddepth);
1950
1951 proj->set_req(0, new_if); // reattach
1952 set_idom(proj, new_if, ddepth);
1953
1954 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1955 guarantee(new_exit != NULL, "null exit node");
1956 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1957
1958 return new_exit;
1959 }
1960
1961 //------------------------------ insert_region_before_proj -------------------------------------
1962 // Insert a region before an if projection (* - new node)
1963 //
1964 // before
1965 // if(test)
1966 // / |
1967 // v |
1968 // proj v
1969 // other-proj
1970 //
1971 // after
1972 // if(test)
1973 // / |
1974 // v |
1975 // * proj-clone v
1976 // | other-proj
1977 // v
1978 // * new-region
1979 // |
1980 // v
1981 // * dum_if
1982 // / \
1983 // v \
1984 // * dum-proj v
1985 // proj
1986 //
1987 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1988 IfNode* iff = proj->in(0)->as_If();
1989 IdealLoopTree *loop = get_loop(proj);
1990 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1991 int ddepth = dom_depth(proj);
1992
1993 _igvn.rehash_node_delayed(iff);
1994 _igvn.rehash_node_delayed(proj);
1995
1996 proj->set_req(0, NULL); // temporary disconnect
1997 ProjNode* proj2 = proj_clone(proj, iff);
1998 register_node(proj2, loop, iff, ddepth);
1999
2000 RegionNode* reg = new RegionNode(2);
2001 reg->set_req(1, proj2);
2002 register_node(reg, loop, iff, ddepth);
2003
2004 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2005 register_node(dum_if, loop, reg, ddepth);
2006
2007 proj->set_req(0, dum_if); // reattach
2008 set_idom(proj, dum_if, ddepth);
2009
2010 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2011 register_node(dum_proj, loop, dum_if, ddepth);
2012
2013 return reg;
2014 }
2015
2016 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2017 // Clone a signed compare loop exit from an unsigned compare and
2018 // insert it before the unsigned cmp on the stay-in-loop path.
2019 // All new nodes inserted in the dominator tree between the original
2020 // if and it's projections. The original if test is replaced with
2021 // a constant to force the stay-in-loop path.
2022 //
2023 // This is done to make sure that the original if and it's projections
2024 // still dominate the same set of control nodes, that the ctrl() relation
2025 // from data nodes to them is preserved, and that their loop nesting is
2026 // preserved.
2027 //
2028 // before
2029 // if(i <u limit) unsigned compare loop exit
2030 // / |
2031 // v v
2032 // exit-proj stay-in-loop-proj
2033 //
2034 // after
2035 // if(stay-in-loop-const) original if
2036 // / |
2037 // / v
2038 // / if(i < limit) new signed test
2039 // / / |
2040 // / / v
2041 // / / if(i <u limit) new cloned unsigned test
2042 // / / / |
2043 // v v v |
2044 // region |
2045 // | |
2046 // dum-if |
2047 // / | |
2048 // ether | |
2049 // v v
2050 // exit-proj stay-in-loop-proj
2051 //
2052 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2053 const bool Signed = true;
2054 const bool Unsigned = false;
2055
2056 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2057 if (bol->_test._test != BoolTest::lt) return NULL;
2058 CmpNode* cmpu = bol->in(1)->as_Cmp();
2059 if (cmpu->Opcode() != Op_CmpU) return NULL;
2060 int stride = stride_of_possible_iv(if_cmpu);
2061 if (stride == 0) return NULL;
2062
2063 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2064 guarantee(lp_proj != NULL, "null loop node");
2065
2066 ProjNode* lp_continue = lp_proj->as_Proj();
2067 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2068
2069 Node* limit = NULL;
2070 if (stride > 0) {
2071 limit = cmpu->in(2);
2072 } else {
2073 limit = _igvn.makecon(TypeInt::ZERO);
2074 set_ctrl(limit, C->root());
2075 }
2076 // Create a new region on the exit path
2077 RegionNode* reg = insert_region_before_proj(lp_exit);
2078 guarantee(reg != NULL, "null region node");
2079
2080 // Clone the if-cmpu-true-false using a signed compare
2081 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2082 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2083 reg->add_req(cmpi_exit);
2084
2085 // Clone the if-cmpu-true-false
2086 BoolTest::mask rel_u = bol->_test._test;
2087 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2088 reg->add_req(cmpu_exit);
2089
2090 // Force original if to stay in loop.
2091 short_circuit_if(if_cmpu, lp_continue);
2092
2093 return cmpi_exit->in(0)->as_If();
2094 }
2095
2096 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2097 // Remove a previously inserted signed compare loop exit.
2098 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2099 Node* lp_proj = stay_in_loop(if_cmp, loop);
2100 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2101 stay_in_loop(lp_proj, loop)->is_If() &&
2102 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2103 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2104 set_ctrl(con, C->root());
2105 if_cmp->set_req(1, con);
2106 }
2107
2108 //------------------------------ scheduled_nodelist -------------------------------------
2109 // Create a post order schedule of nodes that are in the
2110 // "member" set. The list is returned in "sched".
2111 // The first node in "sched" is the loop head, followed by
2112 // nodes which have no inputs in the "member" set, and then
2113 // followed by the nodes that have an immediate input dependence
2114 // on a node in "sched".
2115 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2116
2117 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2118 Arena *a = Thread::current()->resource_area();
2119 VectorSet visited(a);
2120 Node_Stack nstack(a, loop->_body.size());
2121
2122 Node* n = loop->_head; // top of stack is cached in "n"
2123 uint idx = 0;
2124 visited.set(n->_idx);
2125
2126 // Initially push all with no inputs from within member set
2127 for(uint i = 0; i < loop->_body.size(); i++ ) {
2128 Node *elt = loop->_body.at(i);
2129 if (member.test(elt->_idx)) {
2130 bool found = false;
2131 for (uint j = 0; j < elt->req(); j++) {
2132 Node* def = elt->in(j);
2133 if (def && member.test(def->_idx) && def != elt) {
2134 found = true;
2135 break;
2136 }
2137 }
2138 if (!found && elt != loop->_head) {
2139 nstack.push(n, idx);
2140 n = elt;
2141 assert(!visited.test(n->_idx), "not seen yet");
2142 visited.set(n->_idx);
2143 }
2144 }
2145 }
2146
2147 // traverse out's that are in the member set
2148 while (true) {
2149 if (idx < n->outcnt()) {
2150 Node* use = n->raw_out(idx);
2151 idx++;
2152 if (!visited.test_set(use->_idx)) {
2153 if (member.test(use->_idx)) {
2154 nstack.push(n, idx);
2155 n = use;
2156 idx = 0;
2157 }
2158 }
2159 } else {
2160 // All outputs processed
2161 sched.push(n);
2162 if (nstack.is_empty()) break;
2163 n = nstack.node();
2164 idx = nstack.index();
2165 nstack.pop();
2166 }
2167 }
2168 }
2169
2170
2171 //------------------------------ has_use_in_set -------------------------------------
2172 // Has a use in the vector set
2173 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2174 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2175 Node* use = n->fast_out(j);
2176 if (vset.test(use->_idx)) {
2177 return true;
2178 }
2179 }
2180 return false;
2181 }
2182
2183
2184 //------------------------------ has_use_internal_to_set -------------------------------------
2185 // Has use internal to the vector set (ie. not in a phi at the loop head)
2186 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2187 Node* head = loop->_head;
2188 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2189 Node* use = n->fast_out(j);
2190 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2191 return true;
2192 }
2193 }
2194 return false;
2195 }
2196
2197
2198 //------------------------------ clone_for_use_outside_loop -------------------------------------
2199 // clone "n" for uses that are outside of loop
2200 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2201 int cloned = 0;
2202 assert(worklist.size() == 0, "should be empty");
2203 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2204 Node* use = n->fast_out(j);
2205 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2206 worklist.push(use);
2207 }
2208 }
2209 while( worklist.size() ) {
2210 Node *use = worklist.pop();
2211 if (!has_node(use) || use->in(0) == C->top()) continue;
2212 uint j;
2213 for (j = 0; j < use->req(); j++) {
2214 if (use->in(j) == n) break;
2215 }
2216 assert(j < use->req(), "must be there");
2217
2218 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2219 Node* n_clone = n->clone();
2220 _igvn.replace_input_of(use, j, n_clone);
2221 cloned++;
2222 Node* use_c;
2223 if (!use->is_Phi()) {
2224 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2225 } else {
2226 // Use in a phi is considered a use in the associated predecessor block
2227 use_c = use->in(0)->in(j);
2228 }
2229 set_ctrl(n_clone, use_c);
2230 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2231 get_loop(use_c)->_body.push(n_clone);
2232 _igvn.register_new_node_with_optimizer(n_clone);
2233 #if !defined(PRODUCT)
2234 if (TracePartialPeeling) {
2235 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2236 }
2237 #endif
2238 }
2239 return cloned;
2240 }
2241
2242
2243 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2244 // clone "n" for special uses that are in the not_peeled region.
2245 // If these def-uses occur in separate blocks, the code generator
2246 // marks the method as not compilable. For example, if a "BoolNode"
2247 // is in a different basic block than the "IfNode" that uses it, then
2248 // the compilation is aborted in the code generator.
2249 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2250 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2251 if (n->is_Phi() || n->is_Load()) {
2252 return;
2253 }
2254 assert(worklist.size() == 0, "should be empty");
2255 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2256 Node* use = n->fast_out(j);
2257 if ( not_peel.test(use->_idx) &&
2258 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2259 use->in(1) == n) {
2260 worklist.push(use);
2261 }
2262 }
2263 if (worklist.size() > 0) {
2264 // clone "n" and insert it between inputs of "n" and the use
2265 Node* n_clone = n->clone();
2266 loop->_body.push(n_clone);
2267 _igvn.register_new_node_with_optimizer(n_clone);
2268 set_ctrl(n_clone, get_ctrl(n));
2269 sink_list.push(n_clone);
2270 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2271 #if !defined(PRODUCT)
2272 if (TracePartialPeeling) {
2273 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2274 }
2275 #endif
2276 while( worklist.size() ) {
2277 Node *use = worklist.pop();
2278 _igvn.rehash_node_delayed(use);
2279 for (uint j = 1; j < use->req(); j++) {
2280 if (use->in(j) == n) {
2281 use->set_req(j, n_clone);
2282 }
2283 }
2284 }
2285 }
2286 }
2287
2288
2289 //------------------------------ insert_phi_for_loop -------------------------------------
2290 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2291 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2292 Node *phi = PhiNode::make(lp, back_edge_val);
2293 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2294 // Use existing phi if it already exists
2295 Node *hit = _igvn.hash_find_insert(phi);
2296 if( hit == NULL ) {
2297 _igvn.register_new_node_with_optimizer(phi);
2298 set_ctrl(phi, lp);
2299 } else {
2300 // Remove the new phi from the graph and use the hit
2301 _igvn.remove_dead_node(phi);
2302 phi = hit;
2303 }
2304 _igvn.replace_input_of(use, idx, phi);
2305 }
2306
2307 #ifdef ASSERT
2308 //------------------------------ is_valid_loop_partition -------------------------------------
2309 // Validate the loop partition sets: peel and not_peel
2310 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2311 VectorSet& not_peel ) {
2312 uint i;
2313 // Check that peel_list entries are in the peel set
2314 for (i = 0; i < peel_list.size(); i++) {
2315 if (!peel.test(peel_list.at(i)->_idx)) {
2316 return false;
2317 }
2318 }
2319 // Check at loop members are in one of peel set or not_peel set
2320 for (i = 0; i < loop->_body.size(); i++ ) {
2321 Node *def = loop->_body.at(i);
2322 uint di = def->_idx;
2323 // Check that peel set elements are in peel_list
2324 if (peel.test(di)) {
2325 if (not_peel.test(di)) {
2326 return false;
2327 }
2328 // Must be in peel_list also
2329 bool found = false;
2330 for (uint j = 0; j < peel_list.size(); j++) {
2331 if (peel_list.at(j)->_idx == di) {
2332 found = true;
2333 break;
2334 }
2335 }
2336 if (!found) {
2337 return false;
2338 }
2339 } else if (not_peel.test(di)) {
2340 if (peel.test(di)) {
2341 return false;
2342 }
2343 } else {
2344 return false;
2345 }
2346 }
2347 return true;
2348 }
2349
2350 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2351 // Ensure a use outside of loop is of the right form
2352 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2353 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2354 return (use->is_Phi() &&
2355 use_c->is_Region() && use_c->req() == 3 &&
2356 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2357 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2358 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2359 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2360 }
2361
2362 //------------------------------ is_valid_clone_loop_form -------------------------------------
2363 // Ensure that all uses outside of loop are of the right form
2364 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2365 uint orig_exit_idx, uint clone_exit_idx) {
2366 uint len = peel_list.size();
2367 for (uint i = 0; i < len; i++) {
2368 Node *def = peel_list.at(i);
2369
2370 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2371 Node *use = def->fast_out(j);
2372 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2373 if (!loop->is_member(get_loop(use_c))) {
2374 // use is not in the loop, check for correct structure
2375 if (use->in(0) == def) {
2376 // Okay
2377 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2378 return false;
2379 }
2380 }
2381 }
2382 }
2383 return true;
2384 }
2385 #endif
2386
2387 //------------------------------ partial_peel -------------------------------------
2388 // Partially peel (aka loop rotation) the top portion of a loop (called
2389 // the peel section below) by cloning it and placing one copy just before
2390 // the new loop head and the other copy at the bottom of the new loop.
2391 //
2392 // before after where it came from
2393 //
2394 // stmt1 stmt1
2395 // loop: stmt2 clone
2396 // stmt2 if condA goto exitA clone
2397 // if condA goto exitA new_loop: new
2398 // stmt3 stmt3 clone
2399 // if !condB goto loop if condB goto exitB clone
2400 // exitB: stmt2 orig
2401 // stmt4 if !condA goto new_loop orig
2402 // exitA: goto exitA
2403 // exitB:
2404 // stmt4
2405 // exitA:
2406 //
2407 // Step 1: find the cut point: an exit test on probable
2408 // induction variable.
2409 // Step 2: schedule (with cloning) operations in the peel
2410 // section that can be executed after the cut into
2411 // the section that is not peeled. This may need
2412 // to clone operations into exit blocks. For
2413 // instance, a reference to A[i] in the not-peel
2414 // section and a reference to B[i] in an exit block
2415 // may cause a left-shift of i by 2 to be placed
2416 // in the peel block. This step will clone the left
2417 // shift into the exit block and sink the left shift
2418 // from the peel to the not-peel section.
2419 // Step 3: clone the loop, retarget the control, and insert
2420 // phis for values that are live across the new loop
2421 // head. This is very dependent on the graph structure
2422 // from clone_loop. It creates region nodes for
2423 // exit control and associated phi nodes for values
2424 // flow out of the loop through that exit. The region
2425 // node is dominated by the clone's control projection.
2426 // So the clone's peel section is placed before the
2427 // new loop head, and the clone's not-peel section is
2428 // forms the top part of the new loop. The original
2429 // peel section forms the tail of the new loop.
2430 // Step 4: update the dominator tree and recompute the
2431 // dominator depth.
2432 //
2433 // orig
2434 //
2435 // stmt1
2436 // |
2437 // v
2438 // loop predicate
2439 // |
2440 // v
2441 // loop<----+
2442 // | |
2443 // stmt2 |
2444 // | |
2445 // v |
2446 // ifA |
2447 // / | |
2448 // v v |
2449 // false true ^ <-- last_peel
2450 // / | |
2451 // / ===|==cut |
2452 // / stmt3 | <-- first_not_peel
2453 // / | |
2454 // | v |
2455 // v ifB |
2456 // exitA: / \ |
2457 // / \ |
2458 // v v |
2459 // false true |
2460 // / \ |
2461 // / ----+
2462 // |
2463 // v
2464 // exitB:
2465 // stmt4
2466 //
2467 //
2468 // after clone loop
2469 //
2470 // stmt1
2471 // |
2472 // v
2473 // loop predicate
2474 // / \
2475 // clone / \ orig
2476 // / \
2477 // / \
2478 // v v
2479 // +---->loop loop<----+
2480 // | | | |
2481 // | stmt2 stmt2 |
2482 // | | | |
2483 // | v v |
2484 // | ifA ifA |
2485 // | | \ / | |
2486 // | v v v v |
2487 // ^ true false false true ^ <-- last_peel
2488 // | | ^ \ / | |
2489 // | cut==|== \ \ / ===|==cut |
2490 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2491 // | | dom | | | |
2492 // | v \ 1v v2 v |
2493 // | ifB regionA ifB |
2494 // | / \ | / \ |
2495 // | / \ v / \ |
2496 // | v v exitA: v v |
2497 // | true false false true |
2498 // | / ^ \ / \ |
2499 // +---- \ \ / ----+
2500 // dom \ /
2501 // \ 1v v2
2502 // regionB
2503 // |
2504 // v
2505 // exitB:
2506 // stmt4
2507 //
2508 //
2509 // after partial peel
2510 //
2511 // stmt1
2512 // |
2513 // v
2514 // loop predicate
2515 // /
2516 // clone / orig
2517 // / TOP
2518 // / \
2519 // v v
2520 // TOP->loop loop----+
2521 // | | |
2522 // stmt2 stmt2 |
2523 // | | |
2524 // v v |
2525 // ifA ifA |
2526 // | \ / | |
2527 // v v v v |
2528 // true false false true | <-- last_peel
2529 // | ^ \ / +------|---+
2530 // +->newloop \ \ / === ==cut | |
2531 // | stmt3 \ \ / TOP | |
2532 // | | dom | | stmt3 | | <-- first_not_peel
2533 // | v \ 1v v2 v | |
2534 // | ifB regionA ifB ^ v
2535 // | / \ | / \ | |
2536 // | / \ v / \ | |
2537 // | v v exitA: v v | |
2538 // | true false false true | |
2539 // | / ^ \ / \ | |
2540 // | | \ \ / v | |
2541 // | | dom \ / TOP | |
2542 // | | \ 1v v2 | |
2543 // ^ v regionB | |
2544 // | | | | |
2545 // | | v ^ v
2546 // | | exitB: | |
2547 // | | stmt4 | |
2548 // | +------------>-----------------+ |
2549 // | |
2550 // +-----------------<---------------------+
2551 //
2552 //
2553 // final graph
2554 //
2555 // stmt1
2556 // |
2557 // v
2558 // loop predicate
2559 // |
2560 // v
2561 // stmt2 clone
2562 // |
2563 // v
2564 // ........> ifA clone
2565 // : / |
2566 // dom / |
2567 // : v v
2568 // : false true
2569 // : | |
2570 // : | v
2571 // : | newloop<-----+
2572 // : | | |
2573 // : | stmt3 clone |
2574 // : | | |
2575 // : | v |
2576 // : | ifB |
2577 // : | / \ |
2578 // : | v v |
2579 // : | false true |
2580 // : | | | |
2581 // : | v stmt2 |
2582 // : | exitB: | |
2583 // : | stmt4 v |
2584 // : | ifA orig |
2585 // : | / \ |
2586 // : | / \ |
2587 // : | v v |
2588 // : | false true |
2589 // : | / \ |
2590 // : v v -----+
2591 // RegionA
2592 // |
2593 // v
2594 // exitA
2595 //
2596 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2597
2598 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2599 if (!loop->_head->is_Loop()) {
2600 return false; }
2601
2602 LoopNode *head = loop->_head->as_Loop();
2603
2604 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2605 return false;
2606 }
2607
2608 // Check for complex exit control
2609 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2610 Node *n = loop->_body.at(ii);
2611 int opc = n->Opcode();
2612 if (n->is_Call() ||
2613 opc == Op_Catch ||
2614 opc == Op_CatchProj ||
2615 opc == Op_Jump ||
2616 opc == Op_JumpProj) {
2617 #if !defined(PRODUCT)
2618 if (TracePartialPeeling) {
2619 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2620 }
2621 #endif
2622 return false;
2623 }
2624 }
2625
2626 int dd = dom_depth(head);
2627
2628 // Step 1: find cut point
2629
2630 // Walk up dominators to loop head looking for first loop exit
2631 // which is executed on every path thru loop.
2632 IfNode *peel_if = NULL;
2633 IfNode *peel_if_cmpu = NULL;
2634
2635 Node *iff = loop->tail();
2636 while( iff != head ) {
2637 if( iff->is_If() ) {
2638 Node *ctrl = get_ctrl(iff->in(1));
2639 if (ctrl->is_top()) return false; // Dead test on live IF.
2640 // If loop-varying exit-test, check for induction variable
2641 if( loop->is_member(get_loop(ctrl)) &&
2642 loop->is_loop_exit(iff) &&
2643 is_possible_iv_test(iff)) {
2644 Node* cmp = iff->in(1)->in(1);
2645 if (cmp->Opcode() == Op_CmpI) {
2646 peel_if = iff->as_If();
2647 } else {
2648 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2649 peel_if_cmpu = iff->as_If();
2650 }
2651 }
2652 }
2653 iff = idom(iff);
2654 }
2655 // Prefer signed compare over unsigned compare.
2656 IfNode* new_peel_if = NULL;
2657 if (peel_if == NULL) {
2658 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2659 return false; // No peel point found
2660 }
2661 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2662 if (new_peel_if == NULL) {
2663 return false; // No peel point found
2664 }
2665 peel_if = new_peel_if;
2666 }
2667 Node* last_peel = stay_in_loop(peel_if, loop);
2668 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2669 if (first_not_peeled == NULL || first_not_peeled == head) {
2670 return false;
2671 }
2672
2673 #if !defined(PRODUCT)
2674 if (TraceLoopOpts) {
2675 tty->print("PartialPeel ");
2676 loop->dump_head();
2677 }
2678
2679 if (TracePartialPeeling) {
2680 tty->print_cr("before partial peel one iteration");
2681 Node_List wl;
2682 Node* t = head->in(2);
2683 while (true) {
2684 wl.push(t);
2685 if (t == head) break;
2686 t = idom(t);
2687 }
2688 while (wl.size() > 0) {
2689 Node* tt = wl.pop();
2690 tt->dump();
2691 if (tt == last_peel) tty->print_cr("-- cut --");
2692 }
2693 }
2694 #endif
2695 ResourceArea *area = Thread::current()->resource_area();
2696 VectorSet peel(area);
2697 VectorSet not_peel(area);
2698 Node_List peel_list(area);
2699 Node_List worklist(area);
2700 Node_List sink_list(area);
2701
2702 // Set of cfg nodes to peel are those that are executable from
2703 // the head through last_peel.
2704 assert(worklist.size() == 0, "should be empty");
2705 worklist.push(head);
2706 peel.set(head->_idx);
2707 while (worklist.size() > 0) {
2708 Node *n = worklist.pop();
2709 if (n != last_peel) {
2710 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2711 Node* use = n->fast_out(j);
2712 if (use->is_CFG() &&
2713 loop->is_member(get_loop(use)) &&
2714 !peel.test_set(use->_idx)) {
2715 worklist.push(use);
2716 }
2717 }
2718 }
2719 }
2720
2721 // Set of non-cfg nodes to peel are those that are control
2722 // dependent on the cfg nodes.
2723 uint i;
2724 for(i = 0; i < loop->_body.size(); i++ ) {
2725 Node *n = loop->_body.at(i);
2726 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2727 if (peel.test(n_c->_idx)) {
2728 peel.set(n->_idx);
2729 } else {
2730 not_peel.set(n->_idx);
2731 }
2732 }
2733
2734 // Step 2: move operations from the peeled section down into the
2735 // not-peeled section
2736
2737 // Get a post order schedule of nodes in the peel region
2738 // Result in right-most operand.
2739 scheduled_nodelist(loop, peel, peel_list );
2740
2741 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2742
2743 // For future check for too many new phis
2744 uint old_phi_cnt = 0;
2745 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2746 Node* use = head->fast_out(j);
2747 if (use->is_Phi()) old_phi_cnt++;
2748 }
2749
2750 #if !defined(PRODUCT)
2751 if (TracePartialPeeling) {
2752 tty->print_cr("\npeeled list");
2753 }
2754 #endif
2755
2756 // Evacuate nodes in peel region into the not_peeled region if possible
2757 uint new_phi_cnt = 0;
2758 uint cloned_for_outside_use = 0;
2759 for (i = 0; i < peel_list.size();) {
2760 Node* n = peel_list.at(i);
2761 #if !defined(PRODUCT)
2762 if (TracePartialPeeling) n->dump();
2763 #endif
2764 bool incr = true;
2765 if ( !n->is_CFG() ) {
2766
2767 if ( has_use_in_set(n, not_peel) ) {
2768
2769 // If not used internal to the peeled region,
2770 // move "n" from peeled to not_peeled region.
2771
2772 if ( !has_use_internal_to_set(n, peel, loop) ) {
2773
2774 // if not pinned and not a load (which maybe anti-dependent on a store)
2775 // and not a CMove (Matcher expects only bool->cmove).
2776 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2777 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2778 sink_list.push(n);
2779 peel >>= n->_idx; // delete n from peel set.
2780 not_peel <<= n->_idx; // add n to not_peel set.
2781 peel_list.remove(i);
2782 incr = false;
2783 #if !defined(PRODUCT)
2784 if (TracePartialPeeling) {
2785 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2786 n->_idx, get_ctrl(n)->_idx);
2787 }
2788 #endif
2789 }
2790 } else {
2791 // Otherwise check for special def-use cases that span
2792 // the peel/not_peel boundary such as bool->if
2793 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2794 new_phi_cnt++;
2795 }
2796 }
2797 }
2798 if (incr) i++;
2799 }
2800
2801 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2802 #if !defined(PRODUCT)
2803 if (TracePartialPeeling) {
2804 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2805 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2806 }
2807 #endif
2808 if (new_peel_if != NULL) {
2809 remove_cmpi_loop_exit(new_peel_if, loop);
2810 }
2811 // Inhibit more partial peeling on this loop
2812 assert(!head->is_partial_peel_loop(), "not partial peeled");
2813 head->mark_partial_peel_failed();
2814 if (cloned_for_outside_use > 0) {
2815 // Terminate this round of loop opts because
2816 // the graph outside this loop was changed.
2817 C->set_major_progress();
2818 return true;
2819 }
2820 return false;
2821 }
2822
2823 // Step 3: clone loop, retarget control, and insert new phis
2824
2825 // Create new loop head for new phis and to hang
2826 // the nodes being moved (sinked) from the peel region.
2827 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2828 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2829 _igvn.register_new_node_with_optimizer(new_head);
2830 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2831 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2832 set_loop(new_head, loop);
2833 loop->_body.push(new_head);
2834 not_peel.set(new_head->_idx);
2835 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2836 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2837
2838 while (sink_list.size() > 0) {
2839 Node* n = sink_list.pop();
2840 set_ctrl(n, new_head);
2841 }
2842
2843 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2844
2845 clone_loop( loop, old_new, dd );
2846
2847 const uint clone_exit_idx = 1;
2848 const uint orig_exit_idx = 2;
2849 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2850
2851 Node* head_clone = old_new[head->_idx];
2852 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2853 Node* orig_tail_clone = head_clone->in(2);
2854
2855 // Add phi if "def" node is in peel set and "use" is not
2856
2857 for(i = 0; i < peel_list.size(); i++ ) {
2858 Node *def = peel_list.at(i);
2859 if (!def->is_CFG()) {
2860 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2861 Node *use = def->fast_out(j);
2862 if (has_node(use) && use->in(0) != C->top() &&
2863 (!peel.test(use->_idx) ||
2864 (use->is_Phi() && use->in(0) == head)) ) {
2865 worklist.push(use);
2866 }
2867 }
2868 while( worklist.size() ) {
2869 Node *use = worklist.pop();
2870 for (uint j = 1; j < use->req(); j++) {
2871 Node* n = use->in(j);
2872 if (n == def) {
2873
2874 // "def" is in peel set, "use" is not in peel set
2875 // or "use" is in the entry boundary (a phi) of the peel set
2876
2877 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2878
2879 if ( loop->is_member(get_loop( use_c )) ) {
2880 // use is in loop
2881 if (old_new[use->_idx] != NULL) { // null for dead code
2882 Node* use_clone = old_new[use->_idx];
2883 _igvn.replace_input_of(use, j, C->top());
2884 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2885 }
2886 } else {
2887 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2888 // use is not in the loop, check if the live range includes the cut
2889 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2890 if (not_peel.test(lp_if->_idx)) {
2891 assert(j == orig_exit_idx, "use from original loop");
2892 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2893 }
2894 }
2895 }
2896 }
2897 }
2898 }
2899 }
2900
2901 // Step 3b: retarget control
2902
2903 // Redirect control to the new loop head if a cloned node in
2904 // the not_peeled region has control that points into the peeled region.
2905 // This necessary because the cloned peeled region will be outside
2906 // the loop.
2907 // from to
2908 // cloned-peeled <---+
2909 // new_head_clone: | <--+
2910 // cloned-not_peeled in(0) in(0)
2911 // orig-peeled
2912
2913 for(i = 0; i < loop->_body.size(); i++ ) {
2914 Node *n = loop->_body.at(i);
2915 if (!n->is_CFG() && n->in(0) != NULL &&
2916 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2917 Node* n_clone = old_new[n->_idx];
2918 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2919 }
2920 }
2921
2922 // Backedge of the surviving new_head (the clone) is original last_peel
2923 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2924
2925 // Cut first node in original not_peel set
2926 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2927 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2928 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2929
2930 // Copy head_clone back-branch info to original head
2931 // and remove original head's loop entry and
2932 // clone head's back-branch
2933 _igvn.rehash_node_delayed(head); // Multiple edge updates
2934 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2935 head->set_req(LoopNode::LoopBackControl, C->top());
2936 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2937
2938 // Similarly modify the phis
2939 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2940 Node* use = head->fast_out(k);
2941 if (use->is_Phi() && use->outcnt() > 0) {
2942 Node* use_clone = old_new[use->_idx];
2943 _igvn.rehash_node_delayed(use); // Multiple edge updates
2944 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2945 use->set_req(LoopNode::LoopBackControl, C->top());
2946 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2947 }
2948 }
2949
2950 // Step 4: update dominator tree and dominator depth
2951
2952 set_idom(head, orig_tail_clone, dd);
2953 recompute_dom_depth();
2954
2955 // Inhibit more partial peeling on this loop
2956 new_head_clone->set_partial_peel_loop();
2957 C->set_major_progress();
2958 loop->record_for_igvn();
2959
2960 #if !defined(PRODUCT)
2961 if (TracePartialPeeling) {
2962 tty->print_cr("\nafter partial peel one iteration");
2963 Node_List wl(area);
2964 Node* t = last_peel;
2965 while (true) {
2966 wl.push(t);
2967 if (t == head_clone) break;
2968 t = idom(t);
2969 }
2970 while (wl.size() > 0) {
2971 Node* tt = wl.pop();
2972 if (tt == head) tty->print_cr("orig head");
2973 else if (tt == new_head_clone) tty->print_cr("new head");
2974 else if (tt == head_clone) tty->print_cr("clone head");
2975 tt->dump();
2976 }
2977 }
2978 #endif
2979 return true;
2980 }
2981
2982 //------------------------------reorg_offsets----------------------------------
2983 // Reorganize offset computations to lower register pressure. Mostly
2984 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2985 // then alive with the post-incremented trip counter forcing an extra
2986 // register move)
2987 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2988 // Perform it only for canonical counted loops.
2989 // Loop's shape could be messed up by iteration_split_impl.
2990 if (!loop->_head->is_CountedLoop())
2991 return;
2992 if (!loop->_head->as_Loop()->is_valid_counted_loop())
2993 return;
2994
2995 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2996 CountedLoopEndNode *cle = cl->loopexit();
2997 Node *exit = cle->proj_out(false);
2998 Node *phi = cl->phi();
2999
3000 // Check for the special case of folks using the pre-incremented
3001 // trip-counter on the fall-out path (forces the pre-incremented
3002 // and post-incremented trip counter to be live at the same time).
3003 // Fix this by adjusting to use the post-increment trip counter.
3004
3005 bool progress = true;
3006 while (progress) {
3007 progress = false;
3008 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3009 Node* use = phi->fast_out(i); // User of trip-counter
3010 if (!has_ctrl(use)) continue;
3011 Node *u_ctrl = get_ctrl(use);
3012 if (use->is_Phi()) {
3013 u_ctrl = NULL;
3014 for (uint j = 1; j < use->req(); j++)
3015 if (use->in(j) == phi)
3016 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3017 }
3018 IdealLoopTree *u_loop = get_loop(u_ctrl);
3019 // Look for loop-invariant use
3020 if (u_loop == loop) continue;
3021 if (loop->is_member(u_loop)) continue;
3022 // Check that use is live out the bottom. Assuming the trip-counter
3023 // update is right at the bottom, uses of of the loop middle are ok.
3024 if (dom_lca(exit, u_ctrl) != exit) continue;
3025 // Hit! Refactor use to use the post-incremented tripcounter.
3026 // Compute a post-increment tripcounter.
3027 Node *opaq = new Opaque2Node( C, cle->incr() );
3028 register_new_node(opaq, exit);
3029 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3030 set_ctrl(neg_stride, C->root());
3031 Node *post = new AddINode( opaq, neg_stride);
3032 register_new_node(post, exit);
3033 _igvn.rehash_node_delayed(use);
3034 for (uint j = 1; j < use->req(); j++) {
3035 if (use->in(j) == phi)
3036 use->set_req(j, post);
3037 }
3038 // Since DU info changed, rerun loop
3039 progress = true;
3040 break;
3041 }
3042 }
3043
3044 }