1 /*
2 * Copyright (c) 1999, 2023, 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 "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/callnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/castnode.hpp"
35 #include "opto/divnode.hpp"
36 #include "opto/inlinetypenode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/matcher.hpp"
39 #include "opto/mulnode.hpp"
40 #include "opto/movenode.hpp"
41 #include "opto/opaquenode.hpp"
42 #include "opto/rootnode.hpp"
43 #include "opto/subnode.hpp"
44 #include "opto/subtypenode.hpp"
45 #include "utilities/macros.hpp"
46
47 //=============================================================================
48 //------------------------------split_thru_phi---------------------------------
49 // Split Node 'n' through merge point if there is enough win.
50 Node* PhaseIdealLoop::split_thru_phi(Node* n, Node* region, int policy) {
51 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
52 // ConvI2L may have type information on it which is unsafe to push up
53 // so disable this for now
54 return nullptr;
55 }
56
57 // Splitting range check CastIIs through a loop induction Phi can
58 // cause new Phis to be created that are left unrelated to the loop
59 // induction Phi and prevent optimizations (vectorization)
60 if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
61 n->in(1) == region->as_CountedLoop()->phi()) {
62 return nullptr;
63 }
64
65 // Inline types should not be split through Phis because they cannot be merged
66 // through Phi nodes but each value input needs to be merged individually.
67 if (n->is_InlineType()) {
68 return NULL;
69 }
70
71 if (cannot_split_division(n, region)) {
72 return nullptr;
73 }
74
75 int wins = 0;
76 assert(!n->is_CFG(), "");
77 assert(region->is_Region(), "");
78
79 const Type* type = n->bottom_type();
80 const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
81 Node* phi;
82 if (t_oop != nullptr && t_oop->is_known_instance_field()) {
83 int iid = t_oop->instance_id();
84 int index = C->get_alias_index(t_oop);
85 int offset = t_oop->offset();
86 phi = new PhiNode(region, type, nullptr, iid, index, offset);
87 } else {
88 phi = PhiNode::make_blank(region, n);
89 }
90 uint old_unique = C->unique();
91 for (uint i = 1; i < region->req(); i++) {
92 Node* x;
93 Node* the_clone = nullptr;
94 if (region->in(i) == C->top()) {
95 x = C->top(); // Dead path? Use a dead data op
96 } else {
97 x = n->clone(); // Else clone up the data op
98 the_clone = x; // Remember for possible deletion.
99 // Alter data node to use pre-phi inputs
100 if (n->in(0) == region)
101 x->set_req( 0, region->in(i) );
102 for (uint j = 1; j < n->req(); j++) {
103 Node* in = n->in(j);
104 if (in->is_Phi() && in->in(0) == region)
105 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
106 }
107 }
108 // Check for a 'win' on some paths
109 const Type* t = x->Value(&_igvn);
110
111 bool singleton = t->singleton();
112
113 // A TOP singleton indicates that there are no possible values incoming
114 // along a particular edge. In most cases, this is OK, and the Phi will
115 // be eliminated later in an Ideal call. However, we can't allow this to
116 // happen if the singleton occurs on loop entry, as the elimination of
117 // the PhiNode may cause the resulting node to migrate back to a previous
118 // loop iteration.
119 if (singleton && t == Type::TOP) {
120 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
121 // irreducible loop may not be indicated by an affirmative is_Loop());
122 // therefore, the only top we can split thru a phi is on a backedge of
123 // a loop.
124 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
125 }
126
127 if (singleton) {
128 wins++;
129 x = ((PhaseGVN&)_igvn).makecon(t);
130 } else {
131 // We now call Identity to try to simplify the cloned node.
132 // Note that some Identity methods call phase->type(this).
133 // Make sure that the type array is big enough for
134 // our new node, even though we may throw the node away.
135 // (Note: This tweaking with igvn only works because x is a new node.)
136 _igvn.set_type(x, t);
137 // If x is a TypeNode, capture any more-precise type permanently into Node
138 // otherwise it will be not updated during igvn->transform since
139 // igvn->type(x) is set to x->Value() already.
140 x->raise_bottom_type(t);
141 Node* y = x->Identity(&_igvn);
142 if (y != x) {
143 wins++;
144 x = y;
145 } else {
146 y = _igvn.hash_find(x);
147 if (y) {
148 wins++;
149 x = y;
150 } else {
151 // Else x is a new node we are keeping
152 // We do not need register_new_node_with_optimizer
153 // because set_type has already been called.
154 _igvn._worklist.push(x);
155 }
156 }
157 }
158 if (x != the_clone && the_clone != nullptr)
159 _igvn.remove_dead_node(the_clone);
160 phi->set_req( i, x );
161 }
162 // Too few wins?
163 if (wins <= policy) {
164 _igvn.remove_dead_node(phi);
165 return nullptr;
166 }
167
168 // Record Phi
169 register_new_node( phi, region );
170
171 for (uint i2 = 1; i2 < phi->req(); i2++) {
172 Node *x = phi->in(i2);
173 // If we commoned up the cloned 'x' with another existing Node,
174 // the existing Node picks up a new use. We need to make the
175 // existing Node occur higher up so it dominates its uses.
176 Node *old_ctrl;
177 IdealLoopTree *old_loop;
178
179 if (x->is_Con()) {
180 // Constant's control is always root.
181 set_ctrl(x, C->root());
182 continue;
183 }
184 // The occasional new node
185 if (x->_idx >= old_unique) { // Found a new, unplaced node?
186 old_ctrl = nullptr;
187 old_loop = nullptr; // Not in any prior loop
188 } else {
189 old_ctrl = get_ctrl(x);
190 old_loop = get_loop(old_ctrl); // Get prior loop
191 }
192 // New late point must dominate new use
193 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
194 if (new_ctrl == old_ctrl) // Nothing is changed
195 continue;
196
197 IdealLoopTree *new_loop = get_loop(new_ctrl);
198
199 // Don't move x into a loop if its uses are
200 // outside of loop. Otherwise x will be cloned
201 // for each use outside of this loop.
202 IdealLoopTree *use_loop = get_loop(region);
203 if (!new_loop->is_member(use_loop) &&
204 (old_loop == nullptr || !new_loop->is_member(old_loop))) {
205 // Take early control, later control will be recalculated
206 // during next iteration of loop optimizations.
207 new_ctrl = get_early_ctrl(x);
208 new_loop = get_loop(new_ctrl);
209 }
210 // Set new location
211 set_ctrl(x, new_ctrl);
212 // If changing loop bodies, see if we need to collect into new body
213 if (old_loop != new_loop) {
214 if (old_loop && !old_loop->_child)
215 old_loop->_body.yank(x);
216 if (!new_loop->_child)
217 new_loop->_body.push(x); // Collect body info
218 }
219 }
220
221 return phi;
222 }
223
224 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
225 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
226 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
227 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
228 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
229 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
230 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
231 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
232 const Type* zero;
233 switch (n->Opcode()) {
234 case Op_DivI:
235 case Op_ModI:
236 zero = TypeInt::ZERO;
237 break;
238 case Op_DivL:
239 case Op_ModL:
240 zero = TypeLong::ZERO;
241 break;
242 default:
243 return false;
244 }
245
246 assert(n->in(0) == nullptr, "divisions with zero check should already have bailed out earlier in split-if");
247 Node* divisor = n->in(2);
248 return is_divisor_counted_loop_phi(divisor, region) &&
249 loop_phi_backedge_type_contains_zero(divisor, zero);
250 }
251
252 bool PhaseIdealLoop::is_divisor_counted_loop_phi(const Node* divisor, const Node* loop) {
253 return loop->is_BaseCountedLoop() && divisor->is_Phi() && divisor->in(0) == loop;
254 }
255
256 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
257 return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
258 }
259
260 //------------------------------dominated_by------------------------------------
261 // Replace the dominated test with an obvious true or false. Place it on the
262 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
263 // live path up to the dominating control.
264 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool exclude_loop_predicate) {
265 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
266
267 // prevdom is the dominating projection of the dominating test.
268 assert(iff->Opcode() == Op_If ||
269 iff->Opcode() == Op_CountedLoopEnd ||
270 iff->Opcode() == Op_LongCountedLoopEnd ||
271 iff->Opcode() == Op_RangeCheck,
272 "Check this code when new subtype is added");
273
274 int pop = prevdom->Opcode();
275 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
276 if (flip) {
277 if (pop == Op_IfTrue)
278 pop = Op_IfFalse;
279 else
280 pop = Op_IfTrue;
281 }
282 // 'con' is set to true or false to kill the dominated test.
283 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
284 set_ctrl(con, C->root()); // Constant gets a new use
285 // Hack the dominated test
286 _igvn.replace_input_of(iff, 1, con);
287
288 // If I dont have a reachable TRUE and FALSE path following the IfNode then
289 // I can assume this path reaches an infinite loop. In this case it's not
290 // important to optimize the data Nodes - either the whole compilation will
291 // be tossed or this path (and all data Nodes) will go dead.
292 if (iff->outcnt() != 2) return;
293
294 // Make control-dependent data Nodes on the live path (path that will remain
295 // once the dominated IF is removed) become control-dependent on the
296 // dominating projection.
297 Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
298
299 // Loop predicates may have depending checks which should not
300 // be skipped. For example, range check predicate has two checks
301 // for lower and upper bounds.
302 if (dp == nullptr)
303 return;
304
305 ProjNode* dp_proj = dp->as_Proj();
306 ProjNode* unc_proj = iff->proj_out(1 - dp_proj->_con)->as_Proj();
307 if (exclude_loop_predicate &&
308 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != nullptr ||
309 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != nullptr ||
310 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != nullptr)) {
311 // If this is a range check (IfNode::is_range_check), do not
312 // reorder because Compile::allow_range_check_smearing might have
313 // changed the check.
314 return; // Let IGVN transformation change control dependence.
315 }
316
317 IdealLoopTree* old_loop = get_loop(dp);
318
319 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
320 Node* cd = dp->fast_out(i); // Control-dependent node
321 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
322 if (cd->depends_only_on_test() && _igvn.no_dependent_zero_check(cd)) {
323 assert(cd->in(0) == dp, "");
324 _igvn.replace_input_of(cd, 0, prevdom);
325 set_early_ctrl(cd, false);
326 IdealLoopTree* new_loop = get_loop(get_ctrl(cd));
327 if (old_loop != new_loop) {
328 if (!old_loop->_child) {
329 old_loop->_body.yank(cd);
330 }
331 if (!new_loop->_child) {
332 new_loop->_body.push(cd);
333 }
334 }
335 --i;
336 --imax;
337 }
338 }
339 }
340
341 //------------------------------has_local_phi_input----------------------------
342 // Return TRUE if 'n' has Phi inputs from its local block and no other
343 // block-local inputs (all non-local-phi inputs come from earlier blocks)
344 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
345 Node *n_ctrl = get_ctrl(n);
346 // See if some inputs come from a Phi in this block, or from before
347 // this block.
348 uint i;
349 for( i = 1; i < n->req(); i++ ) {
350 Node *phi = n->in(i);
351 if( phi->is_Phi() && phi->in(0) == n_ctrl )
352 break;
353 }
354 if( i >= n->req() )
355 return nullptr; // No Phi inputs; nowhere to clone thru
356
357 // Check for inputs created between 'n' and the Phi input. These
358 // must split as well; they have already been given the chance
359 // (courtesy of a post-order visit) and since they did not we must
360 // recover the 'cost' of splitting them by being very profitable
361 // when splitting 'n'. Since this is unlikely we simply give up.
362 for( i = 1; i < n->req(); i++ ) {
363 Node *m = n->in(i);
364 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
365 // We allow the special case of AddP's with no local inputs.
366 // This allows us to split-up address expressions.
367 if (m->is_AddP() &&
368 get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
369 get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
370 get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
371 // Move the AddP up to the dominating point. That's fine because control of m's inputs
372 // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
373 Node* c = find_non_split_ctrl(idom(n_ctrl));
374 if (c->is_OuterStripMinedLoop()) {
375 c->as_Loop()->verify_strip_mined(1);
376 c = c->in(LoopNode::EntryControl);
377 }
378 set_ctrl_and_loop(m, c);
379 continue;
380 }
381 return nullptr;
382 }
383 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
384 }
385
386 return n_ctrl;
387 }
388
389 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
390 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
391 assert(bt == T_INT || bt == T_LONG, "only for integers");
392 int n_op = n->Opcode();
393
394 if (n_op == Op_LShift(bt)) {
395 // Scale is loop invariant
396 Node* scale = n->in(2);
397 Node* scale_ctrl = get_ctrl(scale);
398 IdealLoopTree* scale_loop = get_loop(scale_ctrl);
399 if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
400 return nullptr;
401 }
402 const TypeInt* scale_t = scale->bottom_type()->isa_int();
403 if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
404 return nullptr; // Dont bother with byte/short masking
405 }
406 // Add must vary with loop (else shift would be loop-invariant)
407 Node* add = n->in(1);
408 Node* add_ctrl = get_ctrl(add);
409 IdealLoopTree* add_loop = get_loop(add_ctrl);
410 if (n_loop != add_loop) {
411 return nullptr; // happens w/ evil ZKM loops
412 }
413
414 // Convert I-V into I+ (0-V); same for V-I
415 if (add->Opcode() == Op_Sub(bt) &&
416 _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
417 assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
418 Node* zero = _igvn.integercon(0, bt);
419 set_ctrl(zero, C->root());
420 Node* neg = SubNode::make(zero, add->in(2), bt);
421 register_new_node(neg, get_ctrl(add->in(2)));
422 add = AddNode::make(add->in(1), neg, bt);
423 register_new_node(add, add_ctrl);
424 }
425 if (add->Opcode() != Op_Add(bt)) return nullptr;
426 assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
427 // See if one add input is loop invariant
428 Node* add_var = add->in(1);
429 Node* add_var_ctrl = get_ctrl(add_var);
430 IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
431 Node* add_invar = add->in(2);
432 Node* add_invar_ctrl = get_ctrl(add_invar);
433 IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
434 if (add_invar_loop == n_loop) {
435 // Swap to find the invariant part
436 add_invar = add_var;
437 add_invar_ctrl = add_var_ctrl;
438 add_invar_loop = add_var_loop;
439 add_var = add->in(2);
440 } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
441 return nullptr;
442 }
443 if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
444 return nullptr; // No invariant part of the add?
445 }
446
447 // Yes! Reshape address expression!
448 Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
449 Node* inv_scale_ctrl =
450 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
451 add_invar_ctrl : scale_ctrl;
452 register_new_node(inv_scale, inv_scale_ctrl);
453 Node* var_scale = LShiftNode::make(add_var, scale, bt);
454 register_new_node(var_scale, n_ctrl);
455 Node* var_add = AddNode::make(var_scale, inv_scale, bt);
456 register_new_node(var_add, n_ctrl);
457 _igvn.replace_node(n, var_add);
458 return var_add;
459 }
460 return nullptr;
461 }
462
463 //------------------------------remix_address_expressions----------------------
464 // Rework addressing expressions to get the most loop-invariant stuff
465 // moved out. We'd like to do all associative operators, but it's especially
466 // important (common) to do address expressions.
467 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
468 if (!has_ctrl(n)) return nullptr;
469 Node* n_ctrl = get_ctrl(n);
470 IdealLoopTree* n_loop = get_loop(n_ctrl);
471
472 // See if 'n' mixes loop-varying and loop-invariant inputs and
473 // itself is loop-varying.
474
475 // Only interested in binary ops (and AddP)
476 if (n->req() < 3 || n->req() > 4) return nullptr;
477
478 Node* n1_ctrl = get_ctrl(n->in( 1));
479 Node* n2_ctrl = get_ctrl(n->in( 2));
480 Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
481 IdealLoopTree* n1_loop = get_loop(n1_ctrl);
482 IdealLoopTree* n2_loop = get_loop(n2_ctrl);
483 IdealLoopTree* n3_loop = get_loop(n3_ctrl);
484
485 // Does one of my inputs spin in a tighter loop than self?
486 if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
487 (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
488 (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
489 return nullptr; // Leave well enough alone
490 }
491
492 // Is at least one of my inputs loop-invariant?
493 if (n1_loop == n_loop &&
494 n2_loop == n_loop &&
495 n3_loop == n_loop) {
496 return nullptr; // No loop-invariant inputs
497 }
498
499 Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
500 if (res != nullptr) {
501 return res;
502 }
503 res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
504 if (res != nullptr) {
505 return res;
506 }
507
508 int n_op = n->Opcode();
509 // Replace (I+V) with (V+I)
510 if (n_op == Op_AddI ||
511 n_op == Op_AddL ||
512 n_op == Op_AddF ||
513 n_op == Op_AddD ||
514 n_op == Op_MulI ||
515 n_op == Op_MulL ||
516 n_op == Op_MulF ||
517 n_op == Op_MulD) {
518 if (n2_loop == n_loop) {
519 assert(n1_loop != n_loop, "");
520 n->swap_edges(1, 2);
521 }
522 }
523
524 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
525 // but not if I2 is a constant.
526 if (n_op == Op_AddP) {
527 if (n2_loop == n_loop && n3_loop != n_loop) {
528 if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
529 Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
530 Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
531 IdealLoopTree* n22loop = get_loop(n22_ctrl);
532 IdealLoopTree* n23_loop = get_loop(n23_ctrl);
533 if (n22loop != n_loop && n22loop->is_member(n_loop) &&
534 n23_loop == n_loop) {
535 Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
536 // Stuff new AddP in the loop preheader
537 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
538 Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
539 register_new_node(add2, n_ctrl);
540 _igvn.replace_node(n, add2);
541 return add2;
542 }
543 }
544 }
545
546 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
547 if (n2_loop != n_loop && n3_loop == n_loop) {
548 if (n->in(3)->Opcode() == Op_AddX) {
549 Node* V = n->in(3)->in(1);
550 Node* I = n->in(3)->in(2);
551 if (is_member(n_loop,get_ctrl(V))) {
552 } else {
553 Node *tmp = V; V = I; I = tmp;
554 }
555 if (!is_member(n_loop,get_ctrl(I))) {
556 Node* add1 = new AddPNode(n->in(1), n->in(2), I);
557 // Stuff new AddP in the loop preheader
558 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
559 Node* add2 = new AddPNode(n->in(1), add1, V);
560 register_new_node(add2, n_ctrl);
561 _igvn.replace_node(n, add2);
562 return add2;
563 }
564 }
565 }
566 }
567
568 return nullptr;
569 }
570
571 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
572 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
573 assert(n->Opcode() == Op_AddI, "sanity");
574 Node * nn = nullptr;
575 Node * in1 = n->in(1);
576 Node * in2 = n->in(2);
577 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
578 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
579 if (loop_n->is_counted() &&
580 loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
581 Matcher::match_rule_supported(Op_MulAddVS2VI) &&
582 Matcher::match_rule_supported(Op_MulAddS2I)) {
583 Node* mul_in1 = in1->in(1);
584 Node* mul_in2 = in1->in(2);
585 Node* mul_in3 = in2->in(1);
586 Node* mul_in4 = in2->in(2);
587 if (mul_in1->Opcode() == Op_LoadS &&
588 mul_in2->Opcode() == Op_LoadS &&
589 mul_in3->Opcode() == Op_LoadS &&
590 mul_in4->Opcode() == Op_LoadS) {
591 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
592 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
593 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
594 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
595 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
596 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
597 // All nodes should be in the same counted loop.
598 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
599 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
600 Node* adr1 = mul_in1->in(MemNode::Address);
601 Node* adr2 = mul_in2->in(MemNode::Address);
602 Node* adr3 = mul_in3->in(MemNode::Address);
603 Node* adr4 = mul_in4->in(MemNode::Address);
604 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
605 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
606 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
607 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
608 register_new_node(nn, get_ctrl(n));
609 _igvn.replace_node(n, nn);
610 return nn;
611 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
612 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
613 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
614 register_new_node(nn, get_ctrl(n));
615 _igvn.replace_node(n, nn);
616 return nn;
617 }
618 }
619 }
620 }
621 }
622 }
623 return nn;
624 }
625
626 //------------------------------conditional_move-------------------------------
627 // Attempt to replace a Phi with a conditional move. We have some pretty
628 // strict profitability requirements. All Phis at the merge point must
629 // be converted, so we can remove the control flow. We need to limit the
630 // number of c-moves to a small handful. All code that was in the side-arms
631 // of the CFG diamond is now speculatively executed. This code has to be
632 // "cheap enough". We are pretty much limited to CFG diamonds that merge
633 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
634 Node *PhaseIdealLoop::conditional_move( Node *region ) {
635
636 assert(region->is_Region(), "sanity check");
637 if (region->req() != 3) return nullptr;
638
639 // Check for CFG diamond
640 Node *lp = region->in(1);
641 Node *rp = region->in(2);
642 if (!lp || !rp) return nullptr;
643 Node *lp_c = lp->in(0);
644 if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
645 IfNode *iff = lp_c->as_If();
646
647 // Check for ops pinned in an arm of the diamond.
648 // Can't remove the control flow in this case
649 if (lp->outcnt() > 1) return nullptr;
650 if (rp->outcnt() > 1) return nullptr;
651
652 IdealLoopTree* r_loop = get_loop(region);
653 assert(r_loop == get_loop(iff), "sanity");
654 // Always convert to CMOVE if all results are used only outside this loop.
655 bool used_inside_loop = (r_loop == _ltree_root);
656
657 // Check profitability
658 int cost = 0;
659 int phis = 0;
660 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
661 Node *out = region->fast_out(i);
662 if (!out->is_Phi()) continue; // Ignore other control edges, etc
663 phis++;
664 PhiNode* phi = out->as_Phi();
665 BasicType bt = phi->type()->basic_type();
666 switch (bt) {
667 case T_DOUBLE:
668 case T_FLOAT:
669 if (C->use_cmove()) {
670 continue; //TODO: maybe we want to add some cost
671 }
672 cost += Matcher::float_cmove_cost(); // Could be very expensive
673 break;
674 case T_LONG: {
675 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
676 }
677 case T_INT: // These all CMOV fine
678 case T_ADDRESS: { // (RawPtr)
679 cost++;
680 break;
681 }
682 case T_NARROWOOP: // Fall through
683 case T_OBJECT: { // Base oops are OK, but not derived oops
684 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
685 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
686 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
687 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
688 // have a Phi for the base here that we convert to a CMOVE all is well
689 // and good. But if the base is dead, we'll not make a CMOVE. Later
690 // the allocator will have to produce a base by creating a CMOVE of the
691 // relevant bases. This puts the allocator in the business of
692 // manufacturing expensive instructions, generally a bad plan.
693 // Just Say No to Conditionally-Moved Derived Pointers.
694 if (tp && tp->offset() != 0)
695 return nullptr;
696 cost++;
697 break;
698 }
699 default:
700 return nullptr; // In particular, can't do memory or I/O
701 }
702 // Add in cost any speculative ops
703 for (uint j = 1; j < region->req(); j++) {
704 Node *proj = region->in(j);
705 Node *inp = phi->in(j);
706 if (inp->isa_InlineType()) {
707 // TODO 8302217 This prevents PhiNode::push_inline_types_through
708 return NULL;
709 }
710 if (get_ctrl(inp) == proj) { // Found local op
711 cost++;
712 // Check for a chain of dependent ops; these will all become
713 // speculative in a CMOV.
714 for (uint k = 1; k < inp->req(); k++)
715 if (get_ctrl(inp->in(k)) == proj)
716 cost += ConditionalMoveLimit; // Too much speculative goo
717 }
718 }
719 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
720 // This will likely Split-If, a higher-payoff operation.
721 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
722 Node* use = phi->fast_out(k);
723 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
724 cost += ConditionalMoveLimit;
725 // Is there a use inside the loop?
726 // Note: check only basic types since CMoveP is pinned.
727 if (!used_inside_loop && is_java_primitive(bt)) {
728 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
729 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
730 used_inside_loop = true;
731 }
732 }
733 }
734 }//for
735 Node* bol = iff->in(1);
736 if (bol->Opcode() == Op_Opaque4) {
737 return nullptr; // Ignore loop predicate checks (the Opaque4 ensures they will go away)
738 }
739 assert(bol->Opcode() == Op_Bool, "Unexpected node");
740 int cmp_op = bol->in(1)->Opcode();
741 if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
742 return nullptr;
743 }
744 // It is expensive to generate flags from a float compare.
745 // Avoid duplicated float compare.
746 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
747
748 float infrequent_prob = PROB_UNLIKELY_MAG(3);
749 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
750 if (used_inside_loop) {
751 if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
752
753 // BlockLayoutByFrequency optimization moves infrequent branch
754 // from hot path. No point in CMOV'ing in such case (110 is used
755 // instead of 100 to take into account not exactness of float value).
756 if (BlockLayoutByFrequency) {
757 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
758 }
759 }
760 // Check for highly predictable branch. No point in CMOV'ing if
761 // we are going to predict accurately all the time.
762 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
763 //keep going
764 } else if (iff->_prob < infrequent_prob ||
765 iff->_prob > (1.0f - infrequent_prob))
766 return nullptr;
767
768 // --------------
769 // Now replace all Phis with CMOV's
770 Node *cmov_ctrl = iff->in(0);
771 uint flip = (lp->Opcode() == Op_IfTrue);
772 Node_List wq;
773 while (1) {
774 PhiNode* phi = nullptr;
775 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
776 Node *out = region->fast_out(i);
777 if (out->is_Phi()) {
778 phi = out->as_Phi();
779 break;
780 }
781 }
782 if (phi == nullptr || _igvn.type(phi) == Type::TOP) {
783 break;
784 }
785 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
786 // Move speculative ops
787 wq.push(phi);
788 while (wq.size() > 0) {
789 Node *n = wq.pop();
790 for (uint j = 1; j < n->req(); j++) {
791 Node* m = n->in(j);
792 if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
793 #ifndef PRODUCT
794 if (PrintOpto && VerifyLoopOptimizations) {
795 tty->print(" speculate: ");
796 m->dump();
797 }
798 #endif
799 set_ctrl(m, cmov_ctrl);
800 wq.push(m);
801 }
802 }
803 }
804 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
805 register_new_node( cmov, cmov_ctrl );
806 _igvn.replace_node( phi, cmov );
807 #ifndef PRODUCT
808 if (TraceLoopOpts) {
809 tty->print("CMOV ");
810 r_loop->dump_head();
811 if (Verbose) {
812 bol->in(1)->dump(1);
813 cmov->dump(1);
814 }
815 }
816 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
817 #endif
818 }
819
820 // The useless CFG diamond will fold up later; see the optimization in
821 // RegionNode::Ideal.
822 _igvn._worklist.push(region);
823
824 return iff->in(1);
825 }
826
827 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
828 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
829 Node* u = m->fast_out(i);
830 if (u->is_CFG()) {
831 if (u->is_NeverBranch()) {
832 u = u->as_NeverBranch()->proj_out(0);
833 enqueue_cfg_uses(u, wq);
834 } else {
835 wq.push(u);
836 }
837 }
838 }
839 }
840
841 // Try moving a store out of a loop, right before the loop
842 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
843 // Store has to be first in the loop body
844 IdealLoopTree *n_loop = get_loop(n_ctrl);
845 if (n->is_Store() && n_loop != _ltree_root &&
846 n_loop->is_loop() && n_loop->_head->is_Loop() &&
847 n->in(0) != nullptr) {
848 Node* address = n->in(MemNode::Address);
849 Node* value = n->in(MemNode::ValueIn);
850 Node* mem = n->in(MemNode::Memory);
851 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
852 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
853
854 // - address and value must be loop invariant
855 // - memory must be a memory Phi for the loop
856 // - Store must be the only store on this memory slice in the
857 // loop: if there's another store following this one then value
858 // written at iteration i by the second store could be overwritten
859 // at iteration i+n by the first store: it's not safe to move the
860 // first store out of the loop
861 // - nothing must observe the memory Phi: it guarantees no read
862 // before the store, we are also guaranteed the store post
863 // dominates the loop head (ignoring a possible early
864 // exit). Otherwise there would be extra Phi involved between the
865 // loop's Phi and the store.
866 // - there must be no early exit from the loop before the Store
867 // (such an exit most of the time would be an extra use of the
868 // memory Phi but sometimes is a bottom memory Phi that takes the
869 // store as input).
870
871 if (!n_loop->is_member(address_loop) &&
872 !n_loop->is_member(value_loop) &&
873 mem->is_Phi() && mem->in(0) == n_loop->_head &&
874 mem->outcnt() == 1 &&
875 mem->in(LoopNode::LoopBackControl) == n) {
876
877 assert(n_loop->_tail != nullptr, "need a tail");
878 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
879
880 // Verify that there's no early exit of the loop before the store.
881 bool ctrl_ok = false;
882 {
883 // Follow control from loop head until n, we exit the loop or
884 // we reach the tail
885 ResourceMark rm;
886 Unique_Node_List wq;
887 wq.push(n_loop->_head);
888
889 for (uint next = 0; next < wq.size(); ++next) {
890 Node *m = wq.at(next);
891 if (m == n->in(0)) {
892 ctrl_ok = true;
893 continue;
894 }
895 assert(!has_ctrl(m), "should be CFG");
896 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
897 ctrl_ok = false;
898 break;
899 }
900 enqueue_cfg_uses(m, wq);
901 if (wq.size() > 10) {
902 ctrl_ok = false;
903 break;
904 }
905 }
906 }
907 if (ctrl_ok) {
908 // move the Store
909 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
910 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
911 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
912 // Disconnect the phi now. An empty phi can confuse other
913 // optimizations in this pass of loop opts.
914 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
915 n_loop->_body.yank(mem);
916
917 set_ctrl_and_loop(n, n->in(0));
918
919 return n;
920 }
921 }
922 }
923 return nullptr;
924 }
925
926 // Try moving a store out of a loop, right after the loop
927 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
928 if (n->is_Store() && n->in(0) != nullptr) {
929 Node *n_ctrl = get_ctrl(n);
930 IdealLoopTree *n_loop = get_loop(n_ctrl);
931 // Store must be in a loop
932 if (n_loop != _ltree_root && !n_loop->_irreducible) {
933 Node* address = n->in(MemNode::Address);
934 Node* value = n->in(MemNode::ValueIn);
935 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
936 // address must be loop invariant
937 if (!n_loop->is_member(address_loop)) {
938 // Store must be last on this memory slice in the loop and
939 // nothing in the loop must observe it
940 Node* phi = nullptr;
941 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
942 Node* u = n->fast_out(i);
943 if (has_ctrl(u)) { // control use?
944 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
945 if (!n_loop->is_member(u_loop)) {
946 continue;
947 }
948 if (u->is_Phi() && u->in(0) == n_loop->_head) {
949 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
950 // multiple phis on the same slice are possible
951 if (phi != nullptr) {
952 return;
953 }
954 phi = u;
955 continue;
956 }
957 }
958 return;
959 }
960 if (phi != nullptr) {
961 // Nothing in the loop before the store (next iteration)
962 // must observe the stored value
963 bool mem_ok = true;
964 {
965 ResourceMark rm;
966 Unique_Node_List wq;
967 wq.push(phi);
968 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
969 Node *m = wq.at(next);
970 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
971 Node* u = m->fast_out(i);
972 if (u->is_Store() || u->is_Phi()) {
973 if (u != n) {
974 wq.push(u);
975 mem_ok = (wq.size() <= 10);
976 }
977 } else {
978 mem_ok = false;
979 break;
980 }
981 }
982 }
983 }
984 if (mem_ok) {
985 // Move the store out of the loop if the LCA of all
986 // users (except for the phi) is outside the loop.
987 Node* hook = new Node(1);
988 hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
989 _igvn.rehash_node_delayed(phi);
990 int count = phi->replace_edge(n, hook, &_igvn);
991 assert(count > 0, "inconsistent phi");
992
993 // Compute latest point this store can go
994 Node* lca = get_late_ctrl(n, get_ctrl(n));
995 if (lca->is_OuterStripMinedLoop()) {
996 lca = lca->in(LoopNode::EntryControl);
997 }
998 if (n_loop->is_member(get_loop(lca))) {
999 // LCA is in the loop - bail out
1000 _igvn.replace_node(hook, n);
1001 return;
1002 }
1003 #ifdef ASSERT
1004 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1005 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1006 n_loop->_head->as_Loop()->verify_strip_mined(1);
1007 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1008 IdealLoopTree* outer_loop = get_loop(outer);
1009 assert(n_loop->_parent == outer_loop, "broken loop tree");
1010 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1011 }
1012 #endif
1013 lca = place_outside_loop(lca, n_loop);
1014 assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1015 assert(get_loop(lca)->_nest < n_loop->_nest || lca->in(0)->is_NeverBranch(), "must not be moved into inner loop");
1016
1017 // Move store out of the loop
1018 _igvn.replace_node(hook, n->in(MemNode::Memory));
1019 _igvn.replace_input_of(n, 0, lca);
1020 set_ctrl_and_loop(n, lca);
1021
1022 // Disconnect the phi now. An empty phi can confuse other
1023 // optimizations in this pass of loop opts..
1024 if (phi->in(LoopNode::LoopBackControl) == phi) {
1025 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1026 n_loop->_body.yank(phi);
1027 }
1028 }
1029 }
1030 }
1031 }
1032 }
1033 }
1034
1035 // If UseArrayMarkWordCheck is enabled, we can't use immutable memory for the flat array check
1036 // because we are loading the mark word which is mutable. Although the bits we are interested in
1037 // are immutable (we check for markWord::unlocked_value), we need to use raw memory to not break
1038 // anti dependency analysis. Below code will attempt to still move flat array checks out of loops,
1039 // mainly to enable loop unswitching.
1040 void PhaseIdealLoop::move_flat_array_check_out_of_loop(Node* n) {
1041 // Skip checks for more than one array
1042 if (n->req() > 3) {
1043 return;
1044 }
1045 Node* mem = n->in(FlatArrayCheckNode::Memory);
1046 Node* array = n->in(FlatArrayCheckNode::ArrayOrKlass)->uncast();
1047 IdealLoopTree* check_loop = get_loop(get_ctrl(n));
1048 IdealLoopTree* ary_loop = get_loop(get_ctrl(array));
1049
1050 // Check if array is loop invariant
1051 if (!check_loop->is_member(ary_loop)) {
1052 // Walk up memory graph from the check until we leave the loop
1053 VectorSet wq;
1054 wq.set(mem->_idx);
1055 while (check_loop->is_member(get_loop(ctrl_or_self(mem)))) {
1056 if (mem->is_Phi()) {
1057 mem = mem->in(1);
1058 } else if (mem->is_MergeMem()) {
1059 mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
1060 } else if (mem->is_Proj()) {
1061 mem = mem->in(0);
1062 } else if (mem->is_MemBar() || mem->is_SafePoint()) {
1063 mem = mem->in(TypeFunc::Memory);
1064 } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
1065 mem = mem->in(MemNode::Memory);
1066 } else {
1067 #ifdef ASSERT
1068 mem->dump();
1069 #endif
1070 ShouldNotReachHere();
1071 }
1072 if (wq.test_set(mem->_idx)) {
1073 return;
1074 }
1075 }
1076 // Replace memory input and re-compute ctrl to move the check out of the loop
1077 _igvn.replace_input_of(n, 1, mem);
1078 set_ctrl_and_loop(n, get_early_ctrl(n));
1079 Node* bol = n->unique_out();
1080 set_ctrl_and_loop(bol, get_early_ctrl(bol));
1081 }
1082 }
1083
1084 //------------------------------split_if_with_blocks_pre-----------------------
1085 // Do the real work in a non-recursive function. Data nodes want to be
1086 // cloned in the pre-order so they can feed each other nicely.
1087 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1088 // Cloning these guys is unlikely to win
1089 int n_op = n->Opcode();
1090 if (n_op == Op_MergeMem) {
1091 return n;
1092 }
1093 if (n->is_Proj()) {
1094 return n;
1095 }
1096
1097 if (UseArrayMarkWordCheck && n->isa_FlatArrayCheck()) {
1098 move_flat_array_check_out_of_loop(n);
1099 return n;
1100 }
1101
1102 // Do not clone-up CmpFXXX variations, as these are always
1103 // followed by a CmpI
1104 if (n->is_Cmp()) {
1105 return n;
1106 }
1107 // Attempt to use a conditional move instead of a phi/branch
1108 if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1109 Node *cmov = conditional_move( n );
1110 if (cmov) {
1111 return cmov;
1112 }
1113 }
1114 if (n->is_CFG() || n->is_LoadStore()) {
1115 return n;
1116 }
1117 if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1118 if (!C->major_progress()) { // If chance of no more loop opts...
1119 _igvn._worklist.push(n); // maybe we'll remove them
1120 }
1121 return n;
1122 }
1123
1124 if (n->is_Con()) {
1125 return n; // No cloning for Con nodes
1126 }
1127
1128 Node *n_ctrl = get_ctrl(n);
1129 if (!n_ctrl) {
1130 return n; // Dead node
1131 }
1132
1133 Node* res = try_move_store_before_loop(n, n_ctrl);
1134 if (res != nullptr) {
1135 return n;
1136 }
1137
1138 // Attempt to remix address expressions for loop invariants
1139 Node *m = remix_address_expressions( n );
1140 if( m ) return m;
1141
1142 if (n_op == Op_AddI) {
1143 Node *nn = convert_add_to_muladd( n );
1144 if ( nn ) return nn;
1145 }
1146
1147 if (n->is_ConstraintCast()) {
1148 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1149 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1150 // Node control inputs don't necessarily agree with loop control info (due to
1151 // transformations happened in between), thus additional dominance check is needed
1152 // to keep loop info valid.
1153 if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1154 _igvn.replace_node(n, dom_cast);
1155 return dom_cast;
1156 }
1157 }
1158
1159 // Determine if the Node has inputs from some local Phi.
1160 // Returns the block to clone thru.
1161 Node *n_blk = has_local_phi_input( n );
1162 if( !n_blk ) return n;
1163
1164 // Do not clone the trip counter through on a CountedLoop
1165 // (messes up the canonical shape).
1166 if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1167 (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1168 return n;
1169 }
1170 // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1171 if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1172 n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1173 return n;
1174 }
1175
1176 // Check for having no control input; not pinned. Allow
1177 // dominating control.
1178 if (n->in(0)) {
1179 Node *dom = idom(n_blk);
1180 if (dom_lca(n->in(0), dom) != n->in(0)) {
1181 return n;
1182 }
1183 }
1184 // Policy: when is it profitable. You must get more wins than
1185 // policy before it is considered profitable. Policy is usually 0,
1186 // so 1 win is considered profitable. Big merges will require big
1187 // cloning, so get a larger policy.
1188 int policy = n_blk->req() >> 2;
1189
1190 // If the loop is a candidate for range check elimination,
1191 // delay splitting through it's phi until a later loop optimization
1192 if (n_blk->is_BaseCountedLoop()) {
1193 IdealLoopTree *lp = get_loop(n_blk);
1194 if (lp && lp->_rce_candidate) {
1195 return n;
1196 }
1197 }
1198
1199 if (must_throttle_split_if()) return n;
1200
1201 // Split 'n' through the merge point if it is profitable
1202 Node *phi = split_thru_phi( n, n_blk, policy );
1203 if (!phi) return n;
1204
1205 // Found a Phi to split thru!
1206 // Replace 'n' with the new phi
1207 _igvn.replace_node( n, phi );
1208 // Moved a load around the loop, 'en-registering' something.
1209 if (n_blk->is_Loop() && n->is_Load() &&
1210 !phi->in(LoopNode::LoopBackControl)->is_Load())
1211 C->set_major_progress();
1212
1213 return phi;
1214 }
1215
1216 static bool merge_point_too_heavy(Compile* C, Node* region) {
1217 // Bail out if the region and its phis have too many users.
1218 int weight = 0;
1219 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1220 weight += region->fast_out(i)->outcnt();
1221 }
1222 int nodes_left = C->max_node_limit() - C->live_nodes();
1223 if (weight * 8 > nodes_left) {
1224 if (PrintOpto) {
1225 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1226 }
1227 return true;
1228 } else {
1229 return false;
1230 }
1231 }
1232
1233 static bool merge_point_safe(Node* region) {
1234 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1235 // having a PhiNode input. This sidesteps the dangerous case where the split
1236 // ConvI2LNode may become TOP if the input Value() does not
1237 // overlap the ConvI2L range, leaving a node which may not dominate its
1238 // uses.
1239 // A better fix for this problem can be found in the BugTraq entry, but
1240 // expediency for Mantis demands this hack.
1241 #ifdef _LP64
1242 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1243 Node* n = region->fast_out(i);
1244 if (n->is_Phi()) {
1245 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1246 Node* m = n->fast_out(j);
1247 if (m->Opcode() == Op_ConvI2L)
1248 return false;
1249 if (m->is_CastII()) {
1250 return false;
1251 }
1252 }
1253 }
1254 }
1255 #endif
1256 return true;
1257 }
1258
1259
1260 //------------------------------place_outside_loop---------------------------------
1261 // Place some computation outside of this loop on the path to the use passed as argument
1262 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1263 Node* head = loop->_head;
1264 assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1265 if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1266 loop = loop->_parent;
1267 assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1268 }
1269
1270 // Pick control right outside the loop
1271 for (;;) {
1272 Node* dom = idom(useblock);
1273 if (loop->is_member(get_loop(dom)) ||
1274 // NeverBranch nodes are not assigned to the loop when constructed
1275 (dom->is_NeverBranch() && loop->is_member(get_loop(dom->in(0))))) {
1276 break;
1277 }
1278 useblock = dom;
1279 }
1280 assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1281 return useblock;
1282 }
1283
1284
1285 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1286 if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1287 return false;
1288 }
1289 if (!n->in(0)->is_Region()) {
1290 return false;
1291 }
1292
1293 Node* region = n->in(0);
1294 Node* dom = idom(region);
1295 if (!dom->is_If() || dom->in(1) != n->in(1)) {
1296 return false;
1297 }
1298 IfNode* dom_if = dom->as_If();
1299 Node* proj_true = dom_if->proj_out(1);
1300 Node* proj_false = dom_if->proj_out(0);
1301
1302 for (uint i = 1; i < region->req(); i++) {
1303 if (is_dominator(proj_true, region->in(i))) {
1304 continue;
1305 }
1306 if (is_dominator(proj_false, region->in(i))) {
1307 continue;
1308 }
1309 return false;
1310 }
1311
1312 return true;
1313 }
1314
1315
1316 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1317 if (must_throttle_split_if()) {
1318 return false;
1319 }
1320
1321 // Do not do 'split-if' if irreducible loops are present.
1322 if (_has_irreducible_loops) {
1323 return false;
1324 }
1325
1326 if (merge_point_too_heavy(C, n_ctrl)) {
1327 return false;
1328 }
1329
1330 // Do not do 'split-if' if some paths are dead. First do dead code
1331 // elimination and then see if its still profitable.
1332 for (uint i = 1; i < n_ctrl->req(); i++) {
1333 if (n_ctrl->in(i) == C->top()) {
1334 return false;
1335 }
1336 }
1337
1338 // If trying to do a 'Split-If' at the loop head, it is only
1339 // profitable if the cmp folds up on BOTH paths. Otherwise we
1340 // risk peeling a loop forever.
1341
1342 // CNC - Disabled for now. Requires careful handling of loop
1343 // body selection for the cloned code. Also, make sure we check
1344 // for any input path not being in the same loop as n_ctrl. For
1345 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1346 // because the alternative loop entry points won't be converted
1347 // into LoopNodes.
1348 IdealLoopTree *n_loop = get_loop(n_ctrl);
1349 for (uint j = 1; j < n_ctrl->req(); j++) {
1350 if (get_loop(n_ctrl->in(j)) != n_loop) {
1351 return false;
1352 }
1353 }
1354
1355 // Check for safety of the merge point.
1356 if (!merge_point_safe(n_ctrl)) {
1357 return false;
1358 }
1359
1360 return true;
1361 }
1362
1363 // Detect if the node is the inner strip-mined loop
1364 // Return: null if it's not the case, or the exit of outer strip-mined loop
1365 static Node* is_inner_of_stripmined_loop(const Node* out) {
1366 Node* out_le = nullptr;
1367
1368 if (out->is_CountedLoopEnd()) {
1369 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1370
1371 if (loop != nullptr && loop->is_strip_mined()) {
1372 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1373 }
1374 }
1375
1376 return out_le;
1377 }
1378
1379 bool PhaseIdealLoop::flatten_array_element_type_check(Node *n) {
1380 // If the CmpP is a subtype check for a value that has just been
1381 // loaded from an array, the subtype check guarantees the value
1382 // can't be stored in a flattened array and the load of the value
1383 // happens with a flattened array check then: push the type check
1384 // through the phi of the flattened array check. This needs special
1385 // logic because the subtype check's input is not a phi but a
1386 // LoadKlass that must first be cloned through the phi.
1387 if (n->Opcode() != Op_CmpP) {
1388 return false;
1389 }
1390
1391 Node* klassptr = n->in(1);
1392 Node* klasscon = n->in(2);
1393
1394 if (klassptr->is_DecodeNarrowPtr()) {
1395 klassptr = klassptr->in(1);
1396 }
1397
1398 if (klassptr->Opcode() != Op_LoadKlass && klassptr->Opcode() != Op_LoadNKlass) {
1399 return false;
1400 }
1401
1402 if (!klasscon->is_Con()) {
1403 return false;
1404 }
1405
1406 Node* addr = klassptr->in(MemNode::Address);
1407
1408 if (!addr->is_AddP()) {
1409 return false;
1410 }
1411
1412 intptr_t offset;
1413 Node* obj = AddPNode::Ideal_base_and_offset(addr, &_igvn, offset);
1414
1415 if (obj == NULL) {
1416 return false;
1417 }
1418
1419 assert(obj != NULL && addr->in(AddPNode::Base) == addr->in(AddPNode::Address), "malformed AddP?");
1420 if (obj->Opcode() == Op_CastPP) {
1421 obj = obj->in(1);
1422 }
1423
1424 if (!obj->is_Phi()) {
1425 return false;
1426 }
1427
1428 Node* region = obj->in(0);
1429
1430 Node* phi = PhiNode::make_blank(region, n->in(1));
1431 for (uint i = 1; i < region->req(); i++) {
1432 Node* in = obj->in(i);
1433 Node* ctrl = region->in(i);
1434 if (addr->in(AddPNode::Base) != obj) {
1435 Node* cast = addr->in(AddPNode::Base);
1436 assert(cast->Opcode() == Op_CastPP && cast->in(0) != NULL, "inconsistent subgraph");
1437 Node* cast_clone = cast->clone();
1438 cast_clone->set_req(0, ctrl);
1439 cast_clone->set_req(1, in);
1440 register_new_node(cast_clone, ctrl);
1441 const Type* tcast = cast_clone->Value(&_igvn);
1442 _igvn.set_type(cast_clone, tcast);
1443 cast_clone->as_Type()->set_type(tcast);
1444 in = cast_clone;
1445 }
1446 Node* addr_clone = addr->clone();
1447 addr_clone->set_req(AddPNode::Base, in);
1448 addr_clone->set_req(AddPNode::Address, in);
1449 register_new_node(addr_clone, ctrl);
1450 _igvn.set_type(addr_clone, addr_clone->Value(&_igvn));
1451 Node* klassptr_clone = klassptr->clone();
1452 klassptr_clone->set_req(2, addr_clone);
1453 register_new_node(klassptr_clone, ctrl);
1454 _igvn.set_type(klassptr_clone, klassptr_clone->Value(&_igvn));
1455 if (klassptr != n->in(1)) {
1456 Node* decode = n->in(1);
1457 assert(decode->is_DecodeNarrowPtr(), "inconsistent subgraph");
1458 Node* decode_clone = decode->clone();
1459 decode_clone->set_req(1, klassptr_clone);
1460 register_new_node(decode_clone, ctrl);
1461 _igvn.set_type(decode_clone, decode_clone->Value(&_igvn));
1462 klassptr_clone = decode_clone;
1463 }
1464 phi->set_req(i, klassptr_clone);
1465 }
1466 register_new_node(phi, region);
1467 Node* orig = n->in(1);
1468 _igvn.replace_input_of(n, 1, phi);
1469 split_if_with_blocks_post(n);
1470 if (n->outcnt() != 0) {
1471 _igvn.replace_input_of(n, 1, orig);
1472 _igvn.remove_dead_node(phi);
1473 }
1474 return true;
1475 }
1476
1477 //------------------------------split_if_with_blocks_post----------------------
1478 // Do the real work in a non-recursive function. CFG hackery wants to be
1479 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1480 // info.
1481 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1482
1483 if (flatten_array_element_type_check(n)) {
1484 return;
1485 }
1486
1487 // Cloning Cmp through Phi's involves the split-if transform.
1488 // FastLock is not used by an If
1489 if (n->is_Cmp() && !n->is_FastLock()) {
1490 Node *n_ctrl = get_ctrl(n);
1491 // Determine if the Node has inputs from some local Phi.
1492 // Returns the block to clone thru.
1493 Node *n_blk = has_local_phi_input(n);
1494 if (n_blk != n_ctrl) {
1495 return;
1496 }
1497
1498 if (!can_split_if(n_ctrl)) {
1499 return;
1500 }
1501
1502 if (n->outcnt() != 1) {
1503 return; // Multiple bool's from 1 compare?
1504 }
1505 Node *bol = n->unique_out();
1506 assert(bol->is_Bool(), "expect a bool here");
1507 if (bol->outcnt() != 1) {
1508 return;// Multiple branches from 1 compare?
1509 }
1510 Node *iff = bol->unique_out();
1511
1512 // Check some safety conditions
1513 if (iff->is_If()) { // Classic split-if?
1514 if (iff->in(0) != n_ctrl) {
1515 return; // Compare must be in same blk as if
1516 }
1517 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1518 // Can't split CMove with different control.
1519 if (get_ctrl(iff) != n_ctrl) {
1520 return;
1521 }
1522 if (get_ctrl(iff->in(2)) == n_ctrl ||
1523 get_ctrl(iff->in(3)) == n_ctrl) {
1524 return; // Inputs not yet split-up
1525 }
1526 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1527 return; // Loop-invar test gates loop-varying CMOVE
1528 }
1529 } else {
1530 return; // some other kind of node, such as an Allocate
1531 }
1532
1533 // When is split-if profitable? Every 'win' on means some control flow
1534 // goes dead, so it's almost always a win.
1535 int policy = 0;
1536 // Split compare 'n' through the merge point if it is profitable
1537 Node *phi = split_thru_phi( n, n_ctrl, policy);
1538 if (!phi) {
1539 return;
1540 }
1541
1542 // Found a Phi to split thru!
1543 // Replace 'n' with the new phi
1544 _igvn.replace_node(n, phi);
1545
1546 // Now split the bool up thru the phi
1547 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1548 guarantee(bolphi != nullptr, "null boolean phi node");
1549
1550 _igvn.replace_node(bol, bolphi);
1551 assert(iff->in(1) == bolphi, "");
1552
1553 if (bolphi->Value(&_igvn)->singleton()) {
1554 return;
1555 }
1556
1557 // Conditional-move? Must split up now
1558 if (!iff->is_If()) {
1559 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1560 _igvn.replace_node(iff, cmovphi);
1561 return;
1562 }
1563
1564 // Now split the IF
1565 do_split_if(iff);
1566 return;
1567 }
1568
1569 // Two identical ifs back to back can be merged
1570 if (try_merge_identical_ifs(n)) {
1571 return;
1572 }
1573
1574 // Check for an IF ready to split; one that has its
1575 // condition codes input coming from a Phi at the block start.
1576 int n_op = n->Opcode();
1577
1578 // Check for an IF being dominated by another IF same test
1579 if (n_op == Op_If ||
1580 n_op == Op_RangeCheck) {
1581 Node *bol = n->in(1);
1582 uint max = bol->outcnt();
1583 // Check for same test used more than once?
1584 if (max > 1 && bol->is_Bool()) {
1585 // Search up IDOMs to see if this IF is dominated.
1586 Node *cutoff = get_ctrl(bol);
1587
1588 // Now search up IDOMs till cutoff, looking for a dominating test
1589 Node *prevdom = n;
1590 Node *dom = idom(prevdom);
1591 while (dom != cutoff) {
1592 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom &&
1593 safe_for_if_replacement(dom)) {
1594 // It's invalid to move control dependent data nodes in the inner
1595 // strip-mined loop, because:
1596 // 1) break validation of LoopNode::verify_strip_mined()
1597 // 2) move code with side-effect in strip-mined loop
1598 // Move to the exit of outer strip-mined loop in that case.
1599 Node* out_le = is_inner_of_stripmined_loop(dom);
1600 if (out_le != nullptr) {
1601 prevdom = out_le;
1602 }
1603 // Replace the dominated test with an obvious true or false.
1604 // Place it on the IGVN worklist for later cleanup.
1605 C->set_major_progress();
1606 dominated_by(prevdom->as_IfProj(), n->as_If(), false, true);
1607 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1608 return;
1609 }
1610 prevdom = dom;
1611 dom = idom(prevdom);
1612 }
1613 }
1614 }
1615
1616 try_sink_out_of_loop(n);
1617
1618 try_move_store_after_loop(n);
1619
1620 // Remove multiple allocations of the same inline type
1621 if (n->is_InlineType()) {
1622 n->as_InlineType()->remove_redundant_allocations(this);
1623 }
1624 }
1625
1626 // Transform:
1627 //
1628 // if (some_condition) {
1629 // // body 1
1630 // } else {
1631 // // body 2
1632 // }
1633 // if (some_condition) {
1634 // // body 3
1635 // } else {
1636 // // body 4
1637 // }
1638 //
1639 // into:
1640 //
1641 //
1642 // if (some_condition) {
1643 // // body 1
1644 // // body 3
1645 // } else {
1646 // // body 2
1647 // // body 4
1648 // }
1649 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1650 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1651 Node *n_ctrl = n->in(0);
1652 IfNode* dom_if = idom(n_ctrl)->as_If();
1653 ProjNode* dom_proj_true = dom_if->proj_out(1);
1654 ProjNode* dom_proj_false = dom_if->proj_out(0);
1655
1656 // Now split the IF
1657 RegionNode* new_false_region;
1658 RegionNode* new_true_region;
1659 do_split_if(n, &new_false_region, &new_true_region);
1660 assert(new_false_region->req() == new_true_region->req(), "");
1661 #ifdef ASSERT
1662 for (uint i = 1; i < new_false_region->req(); ++i) {
1663 assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1664 assert(i == new_false_region->req() - 1 || new_false_region->in(i)->in(0)->in(1) == new_false_region->in(i + 1)->in(0)->in(1), "unexpected shape following split if");
1665 }
1666 #endif
1667 assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1668
1669 // We now have:
1670 // if (some_condition) {
1671 // // body 1
1672 // if (some_condition) {
1673 // body3: // new_true_region
1674 // // body3
1675 // } else {
1676 // goto body4;
1677 // }
1678 // } else {
1679 // // body 2
1680 // if (some_condition) {
1681 // goto body3;
1682 // } else {
1683 // body4: // new_false_region
1684 // // body4;
1685 // }
1686 // }
1687 //
1688
1689 // clone pinned nodes thru the resulting regions
1690 push_pinned_nodes_thru_region(dom_if, new_true_region);
1691 push_pinned_nodes_thru_region(dom_if, new_false_region);
1692
1693 // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1694 // on a projection of n to have the dom_if as a control dependency. We don't want the CastPP to end up with an
1695 // unrelated control dependency.
1696 for (uint i = 1; i < new_false_region->req(); i++) {
1697 if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1698 dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If(), false, false);
1699 } else {
1700 assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1701 dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If(), false, false);
1702 }
1703 }
1704 return true;
1705 }
1706 return false;
1707 }
1708
1709 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1710 for (DUIterator i = region->outs(); region->has_out(i); i++) {
1711 Node* u = region->out(i);
1712 if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1713 continue;
1714 }
1715 assert(u->in(0) == region, "not a control dependent node?");
1716 uint j = 1;
1717 for (; j < u->req(); ++j) {
1718 Node* in = u->in(j);
1719 if (!is_dominator(ctrl_or_self(in), dom_if)) {
1720 break;
1721 }
1722 }
1723 if (j == u->req()) {
1724 Node *phi = PhiNode::make_blank(region, u);
1725 for (uint k = 1; k < region->req(); ++k) {
1726 Node* clone = u->clone();
1727 clone->set_req(0, region->in(k));
1728 register_new_node(clone, region->in(k));
1729 phi->init_req(k, clone);
1730 }
1731 register_new_node(phi, region);
1732 _igvn.replace_node(u, phi);
1733 --i;
1734 }
1735 }
1736 }
1737
1738 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1739 if (!dom->is_CountedLoopEnd()) {
1740 return true;
1741 }
1742 CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1743 CountedLoopNode* cl = le->loopnode();
1744 if (cl == nullptr) {
1745 return true;
1746 }
1747 if (!cl->is_main_loop()) {
1748 return true;
1749 }
1750 if (cl->is_canonical_loop_entry() == nullptr) {
1751 return true;
1752 }
1753 // Further unrolling is possible so loop exit condition might change
1754 return false;
1755 }
1756
1757 // See if a shared loop-varying computation has no loop-varying uses.
1758 // Happens if something is only used for JVM state in uncommon trap exits,
1759 // like various versions of induction variable+offset. Clone the
1760 // computation per usage to allow it to sink out of the loop.
1761 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1762 if (has_ctrl(n) &&
1763 !n->is_Phi() &&
1764 !n->is_Bool() &&
1765 !n->is_Proj() &&
1766 !n->is_MergeMem() &&
1767 !n->is_CMove() &&
1768 n->Opcode() != Op_Opaque4 &&
1769 !n->is_Type()) {
1770 Node *n_ctrl = get_ctrl(n);
1771 IdealLoopTree *n_loop = get_loop(n_ctrl);
1772
1773 if (n->in(0) != nullptr) {
1774 IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1775 if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1776 // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1777 // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1778 // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1779 _igvn.replace_input_of(n, 0, place_outside_loop(n_ctrl, loop_ctrl));
1780 }
1781 }
1782 if (n_loop != _ltree_root && n->outcnt() > 1) {
1783 // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1784 // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1785 Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1786 if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1787 ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1788 assert(!n->is_Store() && !n->is_LoadStore(), "no node with a side effect");
1789 Node* outer_loop_clone = nullptr;
1790 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1791 Node* u = n->last_out(j); // Clone private computation per use
1792 _igvn.rehash_node_delayed(u);
1793 Node* x = n->clone(); // Clone computation
1794 Node* x_ctrl = nullptr;
1795 if (u->is_Phi()) {
1796 // Replace all uses of normal nodes. Replace Phi uses
1797 // individually, so the separate Nodes can sink down
1798 // different paths.
1799 uint k = 1;
1800 while (u->in(k) != n) k++;
1801 u->set_req(k, x);
1802 // x goes next to Phi input path
1803 x_ctrl = u->in(0)->in(k);
1804 // Find control for 'x' next to use but not inside inner loops.
1805 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1806 --j;
1807 } else { // Normal use
1808 if (has_ctrl(u)) {
1809 x_ctrl = get_ctrl(u);
1810 } else {
1811 x_ctrl = u->in(0);
1812 }
1813 // Find control for 'x' next to use but not inside inner loops.
1814 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1815 // Replace all uses
1816 if (u->is_ConstraintCast() && u->bottom_type()->higher_equal(_igvn.type(n)) && u->in(0) == x_ctrl) {
1817 // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1818 // anymore now that we're going to pin n as well
1819 _igvn.replace_node(u, x);
1820 --j;
1821 } else {
1822 int nb = u->replace_edge(n, x, &_igvn);
1823 j -= nb;
1824 }
1825 }
1826
1827 if (n->is_Load()) {
1828 // For loads, add a control edge to a CFG node outside of the loop
1829 // to force them to not combine and return back inside the loop
1830 // during GVN optimization (4641526).
1831 assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1832
1833 IdealLoopTree* x_loop = get_loop(x_ctrl);
1834 Node* x_head = x_loop->_head;
1835 if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1836 // Do not add duplicate LoadNodes to the outer strip mined loop
1837 if (outer_loop_clone != nullptr) {
1838 _igvn.replace_node(x, outer_loop_clone);
1839 continue;
1840 }
1841 outer_loop_clone = x;
1842 }
1843 x->set_req(0, x_ctrl);
1844 } else if (n->in(0) != nullptr){
1845 x->set_req(0, x_ctrl);
1846 }
1847 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1848 assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1849 register_new_node(x, x_ctrl);
1850
1851 // Chain of AddP: (AddP base (AddP base )) must keep the same base after sinking so:
1852 // 1- We don't add a CastPP here when the first one is sunk so if the second one is not, their bases remain
1853 // the same.
1854 // (see 2- below)
1855 assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1856 x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1857 !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1858 if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
1859 !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1860 assert(!x->is_Load(), "load should be pinned");
1861 // Use a cast node to pin clone out of loop
1862 Node* cast = nullptr;
1863 for (uint k = 0; k < x->req(); k++) {
1864 Node* in = x->in(k);
1865 if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
1866 const Type* in_t = _igvn.type(in);
1867 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t, ConstraintCastNode::UnconditionalDependency);
1868 }
1869 if (cast != nullptr) {
1870 register_new_node(cast, x_ctrl);
1871 x->replace_edge(in, cast);
1872 // Chain of AddP:
1873 // 2- A CastPP of the base is only added now that both AddP nodes are sunk
1874 if (x->is_AddP() && k == AddPNode::Base) {
1875 for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1876 Node* u = x->fast_out(i);
1877 if (u->is_AddP() && u->in(AddPNode::Base) == n->in(AddPNode::Base)) {
1878 _igvn.replace_input_of(u, AddPNode::Base, cast);
1879 assert(u->find_out_with(Op_AddP) == nullptr, "more than 2 chained AddP nodes?");
1880 }
1881 }
1882 }
1883 break;
1884 }
1885 }
1886 assert(cast != nullptr, "must have added a cast to pin the node");
1887 }
1888 }
1889 _igvn.remove_dead_node(n);
1890 }
1891 _dom_lca_tags_round = 0;
1892 }
1893 }
1894 }
1895
1896 // Compute the early control of a node by following its inputs until we reach
1897 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
1898 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
1899 Node* early_ctrl = nullptr;
1900 ResourceMark rm;
1901 Unique_Node_List wq;
1902 wq.push(n);
1903 for (uint i = 0; i < wq.size(); i++) {
1904 Node* m = wq.at(i);
1905 Node* c = nullptr;
1906 if (m->is_CFG()) {
1907 c = m;
1908 } else if (m->pinned()) {
1909 c = m->in(0);
1910 } else {
1911 for (uint j = 0; j < m->req(); j++) {
1912 Node* in = m->in(j);
1913 if (in != nullptr) {
1914 wq.push(in);
1915 }
1916 }
1917 }
1918 if (c != nullptr) {
1919 assert(is_dominator(c, n_ctrl), "control input must dominate current control");
1920 if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
1921 early_ctrl = c;
1922 }
1923 }
1924 }
1925 assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
1926 return early_ctrl;
1927 }
1928
1929 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
1930 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1931 Node* u = n->fast_out(i);
1932 if (u->is_Opaque1()) {
1933 return false; // Found loop limit, bugfix for 4677003
1934 }
1935 // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
1936 // get_late_ctrl_with_anti_dep() use their own tag
1937 _dom_lca_tags_round++;
1938 assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
1939
1940 if (u->is_Phi()) {
1941 for (uint j = 1; j < u->req(); ++j) {
1942 if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
1943 return false;
1944 }
1945 }
1946 } else {
1947 Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
1948 if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
1949 return false;
1950 }
1951 }
1952 }
1953 return true;
1954 }
1955
1956 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
1957 if (n->is_Load()) {
1958 ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
1959 }
1960 IdealLoopTree *u_loop = get_loop(ctrl);
1961 if (u_loop == n_loop) {
1962 return false; // Found loop-varying use
1963 }
1964 if (n_loop->is_member(u_loop)) {
1965 return false; // Found use in inner loop
1966 }
1967 return true;
1968 }
1969
1970 //------------------------------split_if_with_blocks---------------------------
1971 // Check for aggressive application of 'split-if' optimization,
1972 // using basic block level info.
1973 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1974 Node* root = C->root();
1975 visited.set(root->_idx); // first, mark root as visited
1976 // Do pre-visit work for root
1977 Node* n = split_if_with_blocks_pre(root);
1978 uint cnt = n->outcnt();
1979 uint i = 0;
1980
1981 while (true) {
1982 // Visit all children
1983 if (i < cnt) {
1984 Node* use = n->raw_out(i);
1985 ++i;
1986 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1987 // Now do pre-visit work for this use
1988 use = split_if_with_blocks_pre(use);
1989 nstack.push(n, i); // Save parent and next use's index.
1990 n = use; // Process all children of current use.
1991 cnt = use->outcnt();
1992 i = 0;
1993 }
1994 }
1995 else {
1996 // All of n's children have been processed, complete post-processing.
1997 if (cnt != 0 && !n->is_Con()) {
1998 assert(has_node(n), "no dead nodes");
1999 split_if_with_blocks_post(n);
2000 }
2001 if (must_throttle_split_if()) {
2002 nstack.clear();
2003 }
2004 if (nstack.is_empty()) {
2005 // Finished all nodes on stack.
2006 break;
2007 }
2008 // Get saved parent node and next use's index. Visit the rest of uses.
2009 n = nstack.node();
2010 cnt = n->outcnt();
2011 i = nstack.index();
2012 nstack.pop();
2013 }
2014 }
2015 }
2016
2017
2018 //=============================================================================
2019 //
2020 // C L O N E A L O O P B O D Y
2021 //
2022
2023 //------------------------------clone_iff--------------------------------------
2024 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2025 // "Nearly" because all Nodes have been cloned from the original in the loop,
2026 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2027 // through the Phi recursively, and return a Bool.
2028 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2029
2030 // Convert this Phi into a Phi merging Bools
2031 uint i;
2032 for (i = 1; i < phi->req(); i++) {
2033 Node *b = phi->in(i);
2034 if (b->is_Phi()) {
2035 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2036 } else {
2037 assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
2038 }
2039 }
2040
2041 Node* n = phi->in(1);
2042 Node* sample_opaque = nullptr;
2043 Node *sample_bool = nullptr;
2044 if (n->Opcode() == Op_Opaque4) {
2045 sample_opaque = n;
2046 sample_bool = n->in(1);
2047 assert(sample_bool->is_Bool(), "wrong type");
2048 } else {
2049 sample_bool = n;
2050 }
2051 Node* sample_cmp = sample_bool->in(1);
2052 const Type* t = Type::TOP;
2053 const TypePtr* at = NULL;
2054 if (sample_cmp->is_FlatArrayCheck()) {
2055 // Left input of a FlatArrayCheckNode is memory, set the (adr) type of the phi accordingly
2056 assert(sample_cmp->in(1)->bottom_type() == Type::MEMORY, "unexpected input type");
2057 t = Type::MEMORY;
2058 at = TypeRawPtr::BOTTOM;
2059 }
2060
2061 // Make Phis to merge the Cmp's inputs.
2062 PhiNode *phi1 = new PhiNode(phi->in(0), t, at);
2063 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2064 for (i = 1; i < phi->req(); i++) {
2065 Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2066 Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2067 phi1->set_req(i, n1);
2068 phi2->set_req(i, n2);
2069 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2070 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2071 }
2072 // See if these Phis have been made before.
2073 // Register with optimizer
2074 Node *hit1 = _igvn.hash_find_insert(phi1);
2075 if (hit1) { // Hit, toss just made Phi
2076 _igvn.remove_dead_node(phi1); // Remove new phi
2077 assert(hit1->is_Phi(), "" );
2078 phi1 = (PhiNode*)hit1; // Use existing phi
2079 } else { // Miss
2080 _igvn.register_new_node_with_optimizer(phi1);
2081 }
2082 Node *hit2 = _igvn.hash_find_insert(phi2);
2083 if (hit2) { // Hit, toss just made Phi
2084 _igvn.remove_dead_node(phi2); // Remove new phi
2085 assert(hit2->is_Phi(), "" );
2086 phi2 = (PhiNode*)hit2; // Use existing phi
2087 } else { // Miss
2088 _igvn.register_new_node_with_optimizer(phi2);
2089 }
2090 // Register Phis with loop/block info
2091 set_ctrl(phi1, phi->in(0));
2092 set_ctrl(phi2, phi->in(0));
2093 // Make a new Cmp
2094 Node *cmp = sample_cmp->clone();
2095 cmp->set_req(1, phi1);
2096 cmp->set_req(2, phi2);
2097 _igvn.register_new_node_with_optimizer(cmp);
2098 set_ctrl(cmp, phi->in(0));
2099
2100 // Make a new Bool
2101 Node *b = sample_bool->clone();
2102 b->set_req(1,cmp);
2103 _igvn.register_new_node_with_optimizer(b);
2104 set_ctrl(b, phi->in(0));
2105
2106 if (sample_opaque != nullptr) {
2107 Node* opaque = sample_opaque->clone();
2108 opaque->set_req(1, b);
2109 _igvn.register_new_node_with_optimizer(opaque);
2110 set_ctrl(opaque, phi->in(0));
2111 return opaque;
2112 }
2113
2114 assert(b->is_Bool(), "");
2115 return b;
2116 }
2117
2118 //------------------------------clone_bool-------------------------------------
2119 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2120 // "Nearly" because all Nodes have been cloned from the original in the loop,
2121 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2122 // through the Phi recursively, and return a Bool.
2123 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2124 uint i;
2125 // Convert this Phi into a Phi merging Bools
2126 for( i = 1; i < phi->req(); i++ ) {
2127 Node *b = phi->in(i);
2128 if( b->is_Phi() ) {
2129 _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2130 } else {
2131 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2132 }
2133 }
2134
2135 Node *sample_cmp = phi->in(1);
2136
2137 // Make Phis to merge the Cmp's inputs.
2138 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2139 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2140 for( uint j = 1; j < phi->req(); j++ ) {
2141 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2142 Node *n1, *n2;
2143 if( cmp_top->is_Cmp() ) {
2144 n1 = cmp_top->in(1);
2145 n2 = cmp_top->in(2);
2146 } else {
2147 n1 = n2 = cmp_top;
2148 }
2149 phi1->set_req( j, n1 );
2150 phi2->set_req( j, n2 );
2151 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2152 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2153 }
2154
2155 // See if these Phis have been made before.
2156 // Register with optimizer
2157 Node *hit1 = _igvn.hash_find_insert(phi1);
2158 if( hit1 ) { // Hit, toss just made Phi
2159 _igvn.remove_dead_node(phi1); // Remove new phi
2160 assert( hit1->is_Phi(), "" );
2161 phi1 = (PhiNode*)hit1; // Use existing phi
2162 } else { // Miss
2163 _igvn.register_new_node_with_optimizer(phi1);
2164 }
2165 Node *hit2 = _igvn.hash_find_insert(phi2);
2166 if( hit2 ) { // Hit, toss just made Phi
2167 _igvn.remove_dead_node(phi2); // Remove new phi
2168 assert( hit2->is_Phi(), "" );
2169 phi2 = (PhiNode*)hit2; // Use existing phi
2170 } else { // Miss
2171 _igvn.register_new_node_with_optimizer(phi2);
2172 }
2173 // Register Phis with loop/block info
2174 set_ctrl(phi1, phi->in(0));
2175 set_ctrl(phi2, phi->in(0));
2176 // Make a new Cmp
2177 Node *cmp = sample_cmp->clone();
2178 cmp->set_req( 1, phi1 );
2179 cmp->set_req( 2, phi2 );
2180 _igvn.register_new_node_with_optimizer(cmp);
2181 set_ctrl(cmp, phi->in(0));
2182
2183 assert( cmp->is_Cmp(), "" );
2184 return (CmpNode*)cmp;
2185 }
2186
2187 //------------------------------sink_use---------------------------------------
2188 // If 'use' was in the loop-exit block, it now needs to be sunk
2189 // below the post-loop merge point.
2190 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
2191 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
2192 set_ctrl(use, post_loop);
2193 for (DUIterator j = use->outs(); use->has_out(j); j++)
2194 sink_use(use->out(j), post_loop);
2195 }
2196 }
2197
2198 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2199 IdealLoopTree* loop, IdealLoopTree* outer_loop,
2200 Node_List*& split_if_set, Node_List*& split_bool_set,
2201 Node_List*& split_cex_set, Node_List& worklist,
2202 uint new_counter, CloneLoopMode mode) {
2203 Node* nnn = old_new[old->_idx];
2204 // Copy uses to a worklist, so I can munge the def-use info
2205 // with impunity.
2206 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2207 worklist.push(old->fast_out(j));
2208
2209 while( worklist.size() ) {
2210 Node *use = worklist.pop();
2211 if (!has_node(use)) continue; // Ignore dead nodes
2212 if (use->in(0) == C->top()) continue;
2213 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2214 // Check for data-use outside of loop - at least one of OLD or USE
2215 // must not be a CFG node.
2216 #ifdef ASSERT
2217 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2218 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2219 assert(mode != IgnoreStripMined, "incorrect cloning mode");
2220 assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2221 }
2222 #endif
2223 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2224
2225 // If the Data use is an IF, that means we have an IF outside of the
2226 // loop that is switching on a condition that is set inside of the
2227 // loop. Happens if people set a loop-exit flag; then test the flag
2228 // in the loop to break the loop, then test is again outside of the
2229 // loop to determine which way the loop exited.
2230 // Loop predicate If node connects to Bool node through Opaque1 node.
2231 //
2232 // If the use is an AllocateArray through its ValidLengthTest input,
2233 // make sure the Bool/Cmp input is cloned down to avoid a Phi between
2234 // the AllocateArray node and its ValidLengthTest input that could cause
2235 // split if to break.
2236 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4 ||
2237 (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2238 // Since this code is highly unlikely, we lazily build the worklist
2239 // of such Nodes to go split.
2240 if (!split_if_set) {
2241 split_if_set = new Node_List();
2242 }
2243 split_if_set->push(use);
2244 }
2245 if (use->is_Bool()) {
2246 if (!split_bool_set) {
2247 split_bool_set = new Node_List();
2248 }
2249 split_bool_set->push(use);
2250 }
2251 if (use->Opcode() == Op_CreateEx) {
2252 if (!split_cex_set) {
2253 split_cex_set = new Node_List();
2254 }
2255 split_cex_set->push(use);
2256 }
2257
2258
2259 // Get "block" use is in
2260 uint idx = 0;
2261 while( use->in(idx) != old ) idx++;
2262 Node *prev = use->is_CFG() ? use : get_ctrl(use);
2263 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2264 Node *cfg = prev->_idx >= new_counter
2265 ? prev->in(2)
2266 : idom(prev);
2267 if( use->is_Phi() ) // Phi use is in prior block
2268 cfg = prev->in(idx); // NOT in block of Phi itself
2269 if (cfg->is_top()) { // Use is dead?
2270 _igvn.replace_input_of(use, idx, C->top());
2271 continue;
2272 }
2273
2274 // If use is referenced through control edge... (idx == 0)
2275 if (mode == IgnoreStripMined && idx == 0) {
2276 LoopNode *head = loop->_head->as_Loop();
2277 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2278 // That node is outside the inner loop, leave it outside the
2279 // outer loop as well to not confuse verification code.
2280 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2281 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2282 continue;
2283 }
2284 }
2285
2286 while(!outer_loop->is_member(get_loop(cfg))) {
2287 prev = cfg;
2288 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
2289 }
2290 // If the use occurs after merging several exits from the loop, then
2291 // old value must have dominated all those exits. Since the same old
2292 // value was used on all those exits we did not need a Phi at this
2293 // merge point. NOW we do need a Phi here. Each loop exit value
2294 // is now merged with the peeled body exit; each exit gets its own
2295 // private Phi and those Phis need to be merged here.
2296 Node *phi;
2297 if( prev->is_Region() ) {
2298 if( idx == 0 ) { // Updating control edge?
2299 phi = prev; // Just use existing control
2300 } else { // Else need a new Phi
2301 phi = PhiNode::make( prev, old );
2302 // Now recursively fix up the new uses of old!
2303 for( uint i = 1; i < prev->req(); i++ ) {
2304 worklist.push(phi); // Onto worklist once for each 'old' input
2305 }
2306 }
2307 } else {
2308 // Get new RegionNode merging old and new loop exits
2309 prev = old_new[prev->_idx];
2310 assert( prev, "just made this in step 7" );
2311 if( idx == 0) { // Updating control edge?
2312 phi = prev; // Just use existing control
2313 } else { // Else need a new Phi
2314 // Make a new Phi merging data values properly
2315 phi = PhiNode::make( prev, old );
2316 phi->set_req( 1, nnn );
2317 }
2318 }
2319 // If inserting a new Phi, check for prior hits
2320 if( idx != 0 ) {
2321 Node *hit = _igvn.hash_find_insert(phi);
2322 if( hit == nullptr ) {
2323 _igvn.register_new_node_with_optimizer(phi); // Register new phi
2324 } else { // or
2325 // Remove the new phi from the graph and use the hit
2326 _igvn.remove_dead_node(phi);
2327 phi = hit; // Use existing phi
2328 }
2329 set_ctrl(phi, prev);
2330 }
2331 // Make 'use' use the Phi instead of the old loop body exit value
2332 assert(use->in(idx) == old, "old is still input of use");
2333 // We notify all uses of old, including use, and the indirect uses,
2334 // that may now be optimized because we have replaced old with phi.
2335 _igvn.add_users_to_worklist(old);
2336 _igvn.replace_input_of(use, idx, phi);
2337 if( use->_idx >= new_counter ) { // If updating new phis
2338 // Not needed for correctness, but prevents a weak assert
2339 // in AddPNode from tripping (when we end up with different
2340 // base & derived Phis that will become the same after
2341 // IGVN does CSE).
2342 Node *hit = _igvn.hash_find_insert(use);
2343 if( hit ) // Go ahead and re-hash for hits.
2344 _igvn.replace_node( use, hit );
2345 }
2346
2347 // If 'use' was in the loop-exit block, it now needs to be sunk
2348 // below the post-loop merge point.
2349 sink_use( use, prev );
2350 }
2351 }
2352 }
2353
2354 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2355 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2356 bool check_old_new) {
2357 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2358 Node* u = n->fast_out(j);
2359 assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2360 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2361 Node* c = phase->get_ctrl(u);
2362 IdealLoopTree* u_loop = phase->get_loop(c);
2363 assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2364 if (!loop->is_member(u_loop)) {
2365 if (outer_loop->is_member(u_loop)) {
2366 wq.push(u);
2367 } else {
2368 // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2369 // the outer loop too
2370 Node* u_c = u->in(0);
2371 if (u_c != nullptr) {
2372 IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2373 if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2374 wq.push(u);
2375 }
2376 }
2377 }
2378 }
2379 }
2380 }
2381 }
2382
2383 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2384 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2385 Node_List& extra_data_nodes) {
2386 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2387 CountedLoopNode* cl = head->as_CountedLoop();
2388 Node* l = cl->outer_loop();
2389 Node* tail = cl->outer_loop_tail();
2390 IfNode* le = cl->outer_loop_end();
2391 Node* sfpt = cl->outer_safepoint();
2392 CountedLoopEndNode* cle = cl->loopexit();
2393 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2394 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2395 Node* cle_out = cle->proj_out(false);
2396
2397 Node* new_sfpt = nullptr;
2398 Node* new_cle_out = cle_out->clone();
2399 old_new.map(cle_out->_idx, new_cle_out);
2400 if (mode == CloneIncludesStripMined) {
2401 // clone outer loop body
2402 Node* new_l = l->clone();
2403 Node* new_tail = tail->clone();
2404 IfNode* new_le = le->clone()->as_If();
2405 new_sfpt = sfpt->clone();
2406
2407 set_loop(new_l, outer_loop->_parent);
2408 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2409 set_loop(new_cle_out, outer_loop->_parent);
2410 set_idom(new_cle_out, new_cle, dd);
2411 set_loop(new_sfpt, outer_loop->_parent);
2412 set_idom(new_sfpt, new_cle_out, dd);
2413 set_loop(new_le, outer_loop->_parent);
2414 set_idom(new_le, new_sfpt, dd);
2415 set_loop(new_tail, outer_loop->_parent);
2416 set_idom(new_tail, new_le, dd);
2417 set_idom(new_cl, new_l, dd);
2418
2419 old_new.map(l->_idx, new_l);
2420 old_new.map(tail->_idx, new_tail);
2421 old_new.map(le->_idx, new_le);
2422 old_new.map(sfpt->_idx, new_sfpt);
2423
2424 new_l->set_req(LoopNode::LoopBackControl, new_tail);
2425 new_l->set_req(0, new_l);
2426 new_tail->set_req(0, new_le);
2427 new_le->set_req(0, new_sfpt);
2428 new_sfpt->set_req(0, new_cle_out);
2429 new_cle_out->set_req(0, new_cle);
2430 new_cl->set_req(LoopNode::EntryControl, new_l);
2431
2432 _igvn.register_new_node_with_optimizer(new_l);
2433 _igvn.register_new_node_with_optimizer(new_tail);
2434 _igvn.register_new_node_with_optimizer(new_le);
2435 } else {
2436 Node *newhead = old_new[loop->_head->_idx];
2437 newhead->as_Loop()->clear_strip_mined();
2438 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2439 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2440 }
2441 // Look at data node that were assigned a control in the outer
2442 // loop: they are kept in the outer loop by the safepoint so start
2443 // from the safepoint node's inputs.
2444 IdealLoopTree* outer_loop = get_loop(l);
2445 Node_Stack stack(2);
2446 stack.push(sfpt, 1);
2447 uint new_counter = C->unique();
2448 while (stack.size() > 0) {
2449 Node* n = stack.node();
2450 uint i = stack.index();
2451 while (i < n->req() &&
2452 (n->in(i) == nullptr ||
2453 !has_ctrl(n->in(i)) ||
2454 get_loop(get_ctrl(n->in(i))) != outer_loop ||
2455 (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2456 i++;
2457 }
2458 if (i < n->req()) {
2459 stack.set_index(i+1);
2460 stack.push(n->in(i), 0);
2461 } else {
2462 assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2463 Node* m = n == sfpt ? new_sfpt : n->clone();
2464 if (m != nullptr) {
2465 for (uint i = 0; i < n->req(); i++) {
2466 if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2467 m->set_req(i, old_new[m->in(i)->_idx]);
2468 }
2469 }
2470 } else {
2471 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2472 }
2473 if (n != sfpt) {
2474 extra_data_nodes.push(n);
2475 _igvn.register_new_node_with_optimizer(m);
2476 assert(get_ctrl(n) == cle_out, "what other control?");
2477 set_ctrl(m, new_cle_out);
2478 old_new.map(n->_idx, m);
2479 }
2480 stack.pop();
2481 }
2482 }
2483 if (mode == CloneIncludesStripMined) {
2484 _igvn.register_new_node_with_optimizer(new_sfpt);
2485 _igvn.register_new_node_with_optimizer(new_cle_out);
2486 }
2487 // Some other transformation may have pessimistically assigned some
2488 // data nodes to the outer loop. Set their control so they are out
2489 // of the outer loop.
2490 ResourceMark rm;
2491 Unique_Node_List wq;
2492 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2493 Node* old = extra_data_nodes.at(i);
2494 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2495 }
2496
2497 for (uint i = 0; i < loop->_body.size(); i++) {
2498 Node* old = loop->_body.at(i);
2499 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2500 }
2501
2502 Node* inner_out = sfpt->in(0);
2503 if (inner_out->outcnt() > 1) {
2504 collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2505 }
2506
2507 Node* new_ctrl = cl->outer_loop_exit();
2508 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2509 for (uint i = 0; i < wq.size(); i++) {
2510 Node* n = wq.at(i);
2511 set_ctrl(n, new_ctrl);
2512 if (n->in(0) != nullptr) {
2513 _igvn.replace_input_of(n, 0, new_ctrl);
2514 }
2515 collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2516 }
2517 } else {
2518 Node *newhead = old_new[loop->_head->_idx];
2519 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2520 }
2521 }
2522
2523 //------------------------------clone_loop-------------------------------------
2524 //
2525 // C L O N E A L O O P B O D Y
2526 //
2527 // This is the basic building block of the loop optimizations. It clones an
2528 // entire loop body. It makes an old_new loop body mapping; with this mapping
2529 // you can find the new-loop equivalent to an old-loop node. All new-loop
2530 // nodes are exactly equal to their old-loop counterparts, all edges are the
2531 // same. All exits from the old-loop now have a RegionNode that merges the
2532 // equivalent new-loop path. This is true even for the normal "loop-exit"
2533 // condition. All uses of loop-invariant old-loop values now come from (one
2534 // or more) Phis that merge their new-loop equivalents.
2535 //
2536 // This operation leaves the graph in an illegal state: there are two valid
2537 // control edges coming from the loop pre-header to both loop bodies. I'll
2538 // definitely have to hack the graph after running this transform.
2539 //
2540 // From this building block I will further edit edges to perform loop peeling
2541 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2542 //
2543 // Parameter side_by_size_idom:
2544 // When side_by_size_idom is null, the dominator tree is constructed for
2545 // the clone loop to dominate the original. Used in construction of
2546 // pre-main-post loop sequence.
2547 // When nonnull, the clone and original are side-by-side, both are
2548 // dominated by the side_by_side_idom node. Used in construction of
2549 // unswitched loops.
2550 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2551 CloneLoopMode mode, Node* side_by_side_idom) {
2552
2553 LoopNode* head = loop->_head->as_Loop();
2554 head->verify_strip_mined(1);
2555
2556 if (C->do_vector_loop() && PrintOpto) {
2557 const char* mname = C->method()->name()->as_quoted_ascii();
2558 if (mname != nullptr) {
2559 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2560 }
2561 }
2562
2563 CloneMap& cm = C->clone_map();
2564 if (C->do_vector_loop()) {
2565 cm.set_clone_idx(cm.max_gen()+1);
2566 #ifndef PRODUCT
2567 if (PrintOpto) {
2568 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2569 loop->dump_head();
2570 }
2571 #endif
2572 }
2573
2574 // Step 1: Clone the loop body. Make the old->new mapping.
2575 clone_loop_body(loop->_body, old_new, &cm);
2576
2577 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2578
2579 // Step 2: Fix the edges in the new body. If the old input is outside the
2580 // loop use it. If the old input is INside the loop, use the corresponding
2581 // new node instead.
2582 fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2583
2584 Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2585 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2586
2587 // Step 3: Now fix control uses. Loop varying control uses have already
2588 // been fixed up (as part of all input edges in Step 2). Loop invariant
2589 // control uses must be either an IfFalse or an IfTrue. Make a merge
2590 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2591 // refer to this.
2592 Node_List worklist;
2593 uint new_counter = C->unique();
2594 fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2595
2596 // Step 4: If loop-invariant use is not control, it must be dominated by a
2597 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2598 // there if needed. Make a Phi there merging old and new used values.
2599 Node_List *split_if_set = nullptr;
2600 Node_List *split_bool_set = nullptr;
2601 Node_List *split_cex_set = nullptr;
2602 fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2603
2604 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2605 Node* old = extra_data_nodes.at(i);
2606 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2607 split_bool_set, split_cex_set, worklist, new_counter,
2608 mode);
2609 }
2610
2611 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2612 // the loop uses a condition set in the loop. The original IF probably
2613 // takes control from one or more OLD Regions (which in turn get from NEW
2614 // Regions). In any case, there will be a set of Phis for each merge point
2615 // from the IF up to where the original BOOL def exists the loop.
2616 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2617
2618 }
2619
2620 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2621 if (split_if_set) {
2622 while (split_if_set->size()) {
2623 Node *iff = split_if_set->pop();
2624 uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2625 if (iff->in(input)->is_Phi()) {
2626 Node *b = clone_iff(iff->in(input)->as_Phi());
2627 _igvn.replace_input_of(iff, input, b);
2628 }
2629 }
2630 }
2631 if (split_bool_set) {
2632 while (split_bool_set->size()) {
2633 Node *b = split_bool_set->pop();
2634 Node *phi = b->in(1);
2635 assert(phi->is_Phi(), "");
2636 CmpNode *cmp = clone_bool((PhiNode*) phi);
2637 _igvn.replace_input_of(b, 1, cmp);
2638 }
2639 }
2640 if (split_cex_set) {
2641 while (split_cex_set->size()) {
2642 Node *b = split_cex_set->pop();
2643 assert(b->in(0)->is_Region(), "");
2644 assert(b->in(1)->is_Phi(), "");
2645 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2646 split_up(b, b->in(0), nullptr);
2647 }
2648 }
2649 }
2650
2651 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2652 uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2653 Node_List*& split_bool_set, Node_List*& split_cex_set) {
2654 for(uint i = 0; i < body.size(); i++ ) {
2655 Node* old = body.at(i);
2656 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2657 split_bool_set, split_cex_set, worklist, new_counter,
2658 mode);
2659 }
2660 }
2661
2662 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2663 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2664 LoopNode* head = loop->_head->as_Loop();
2665 for(uint i = 0; i < body.size(); i++ ) {
2666 Node* old = body.at(i);
2667 if( !old->is_CFG() ) continue;
2668
2669 // Copy uses to a worklist, so I can munge the def-use info
2670 // with impunity.
2671 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2672 worklist.push(old->fast_out(j));
2673 }
2674
2675 while (worklist.size()) { // Visit all uses
2676 Node *use = worklist.pop();
2677 if (!has_node(use)) continue; // Ignore dead nodes
2678 IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2679 if (!loop->is_member(use_loop) && use->is_CFG()) {
2680 // Both OLD and USE are CFG nodes here.
2681 assert(use->is_Proj(), "" );
2682 Node* nnn = old_new[old->_idx];
2683
2684 Node* newuse = nullptr;
2685 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2686 CountedLoopNode* cl = head->as_CountedLoop();
2687 CountedLoopEndNode* cle = cl->loopexit();
2688 Node* cle_out = cle->proj_out_or_null(false);
2689 if (use == cle_out) {
2690 IfNode* le = cl->outer_loop_end();
2691 use = le->proj_out(false);
2692 use_loop = get_loop(use);
2693 if (mode == CloneIncludesStripMined) {
2694 nnn = old_new[le->_idx];
2695 } else {
2696 newuse = old_new[cle_out->_idx];
2697 }
2698 }
2699 }
2700 if (newuse == nullptr) {
2701 newuse = use->clone();
2702 }
2703
2704 // Clone the loop exit control projection
2705 if (C->do_vector_loop() && cm != nullptr) {
2706 cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2707 }
2708 newuse->set_req(0,nnn);
2709 _igvn.register_new_node_with_optimizer(newuse);
2710 set_loop(newuse, use_loop);
2711 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2712
2713 // We need a Region to merge the exit from the peeled body and the
2714 // exit from the old loop body.
2715 RegionNode *r = new RegionNode(3);
2716 // Map the old use to the new merge point
2717 old_new.map( use->_idx, r );
2718 uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2719 assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2720
2721 // The original user of 'use' uses 'r' instead.
2722 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2723 Node* useuse = use->last_out(l);
2724 _igvn.rehash_node_delayed(useuse);
2725 uint uses_found = 0;
2726 if (useuse->in(0) == use) {
2727 useuse->set_req(0, r);
2728 uses_found++;
2729 if (useuse->is_CFG()) {
2730 // This is not a dom_depth > dd_r because when new
2731 // control flow is constructed by a loop opt, a node and
2732 // its dominator can end up at the same dom_depth
2733 assert(dom_depth(useuse) >= dd_r, "");
2734 set_idom(useuse, r, dom_depth(useuse));
2735 }
2736 }
2737 for (uint k = 1; k < useuse->req(); k++) {
2738 if( useuse->in(k) == use ) {
2739 useuse->set_req(k, r);
2740 uses_found++;
2741 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2742 // This is not a dom_depth > dd_r because when new
2743 // control flow is constructed by a loop opt, a node
2744 // and its dominator can end up at the same dom_depth
2745 assert(dom_depth(useuse) >= dd_r , "");
2746 set_idom(useuse, r, dom_depth(useuse));
2747 }
2748 }
2749 }
2750 l -= uses_found; // we deleted 1 or more copies of this edge
2751 }
2752
2753 // Now finish up 'r'
2754 r->set_req(1, newuse);
2755 r->set_req(2, use);
2756 _igvn.register_new_node_with_optimizer(r);
2757 set_loop(r, use_loop);
2758 set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2759 } // End of if a loop-exit test
2760 }
2761 }
2762 }
2763
2764 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2765 IdealLoopTree* parent, bool partial) {
2766 for(uint i = 0; i < body.size(); i++ ) {
2767 Node *old = body.at(i);
2768 Node *nnn = old_new[old->_idx];
2769 // Fix CFG/Loop controlling the new node
2770 if (has_ctrl(old)) {
2771 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2772 } else {
2773 set_loop(nnn, parent);
2774 if (old->outcnt() > 0) {
2775 Node* dom = idom(old);
2776 if (old_new[dom->_idx] != nullptr) {
2777 dom = old_new[dom->_idx];
2778 set_idom(nnn, dom, dd );
2779 }
2780 }
2781 }
2782 // Correct edges to the new node
2783 for (uint j = 0; j < nnn->req(); j++) {
2784 Node *n = nnn->in(j);
2785 if (n != nullptr) {
2786 IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2787 if (loop->is_member(old_in_loop)) {
2788 if (old_new[n->_idx] != nullptr) {
2789 nnn->set_req(j, old_new[n->_idx]);
2790 } else {
2791 assert(!body.contains(n), "");
2792 assert(partial, "node not cloned");
2793 }
2794 }
2795 }
2796 }
2797 _igvn.hash_find_insert(nnn);
2798 }
2799 }
2800
2801 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2802 for (uint i = 0; i < body.size(); i++) {
2803 Node* old = body.at(i);
2804 Node* nnn = old->clone();
2805 old_new.map(old->_idx, nnn);
2806 if (old->is_reduction()) {
2807 // Reduction flag is not copied by default. Copy it here when cloning the entire loop body.
2808 nnn->add_flag(Node::Flag_is_reduction);
2809 }
2810 if (C->do_vector_loop() && cm != nullptr) {
2811 cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2812 }
2813 _igvn.register_new_node_with_optimizer(nnn);
2814 }
2815 }
2816
2817
2818 //---------------------- stride_of_possible_iv -------------------------------------
2819 // Looks for an iff/bool/comp with one operand of the compare
2820 // being a cycle involving an add and a phi,
2821 // with an optional truncation (left-shift followed by a right-shift)
2822 // of the add. Returns zero if not an iv.
2823 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2824 Node* trunc1 = nullptr;
2825 Node* trunc2 = nullptr;
2826 const TypeInteger* ttype = nullptr;
2827 if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
2828 return 0;
2829 }
2830 BoolNode* bl = iff->in(1)->as_Bool();
2831 Node* cmp = bl->in(1);
2832 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2833 return 0;
2834 }
2835 // Must have an invariant operand
2836 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2837 return 0;
2838 }
2839 Node* add2 = nullptr;
2840 Node* cmp1 = cmp->in(1);
2841 if (cmp1->is_Phi()) {
2842 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2843 Node* phi = cmp1;
2844 for (uint i = 1; i < phi->req(); i++) {
2845 Node* in = phi->in(i);
2846 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2847 &trunc1, &trunc2, &ttype, T_INT);
2848 if (add && add->in(1) == phi) {
2849 add2 = add->in(2);
2850 break;
2851 }
2852 }
2853 } else {
2854 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2855 Node* addtrunc = cmp1;
2856 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2857 &trunc1, &trunc2, &ttype, T_INT);
2858 if (add && add->in(1)->is_Phi()) {
2859 Node* phi = add->in(1);
2860 for (uint i = 1; i < phi->req(); i++) {
2861 if (phi->in(i) == addtrunc) {
2862 add2 = add->in(2);
2863 break;
2864 }
2865 }
2866 }
2867 }
2868 if (add2 != nullptr) {
2869 const TypeInt* add2t = _igvn.type(add2)->is_int();
2870 if (add2t->is_con()) {
2871 return add2t->get_con();
2872 }
2873 }
2874 return 0;
2875 }
2876
2877
2878 //---------------------- stay_in_loop -------------------------------------
2879 // Return the (unique) control output node that's in the loop (if it exists.)
2880 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2881 Node* unique = nullptr;
2882 if (!n) return nullptr;
2883 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2884 Node* use = n->fast_out(i);
2885 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2886 if (unique != nullptr) {
2887 return nullptr;
2888 }
2889 unique = use;
2890 }
2891 }
2892 return unique;
2893 }
2894
2895 //------------------------------ register_node -------------------------------------
2896 // Utility to register node "n" with PhaseIdealLoop
2897 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2898 _igvn.register_new_node_with_optimizer(n);
2899 loop->_body.push(n);
2900 if (n->is_CFG()) {
2901 set_loop(n, loop);
2902 set_idom(n, pred, ddepth);
2903 } else {
2904 set_ctrl(n, pred);
2905 }
2906 }
2907
2908 //------------------------------ proj_clone -------------------------------------
2909 // Utility to create an if-projection
2910 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2911 ProjNode* c = p->clone()->as_Proj();
2912 c->set_req(0, iff);
2913 return c;
2914 }
2915
2916 //------------------------------ short_circuit_if -------------------------------------
2917 // Force the iff control output to be the live_proj
2918 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2919 guarantee(live_proj != nullptr, "null projection");
2920 int proj_con = live_proj->_con;
2921 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2922 Node *con = _igvn.intcon(proj_con);
2923 set_ctrl(con, C->root());
2924 if (iff) {
2925 iff->set_req(1, con);
2926 }
2927 return con;
2928 }
2929
2930 //------------------------------ insert_if_before_proj -------------------------------------
2931 // Insert a new if before an if projection (* - new node)
2932 //
2933 // before
2934 // if(test)
2935 // / \
2936 // v v
2937 // other-proj proj (arg)
2938 //
2939 // after
2940 // if(test)
2941 // / \
2942 // / v
2943 // | * proj-clone
2944 // v |
2945 // other-proj v
2946 // * new_if(relop(cmp[IU](left,right)))
2947 // / \
2948 // v v
2949 // * new-proj proj
2950 // (returned)
2951 //
2952 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2953 IfNode* iff = proj->in(0)->as_If();
2954 IdealLoopTree *loop = get_loop(proj);
2955 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2956 int ddepth = dom_depth(proj);
2957
2958 _igvn.rehash_node_delayed(iff);
2959 _igvn.rehash_node_delayed(proj);
2960
2961 proj->set_req(0, nullptr); // temporary disconnect
2962 ProjNode* proj2 = proj_clone(proj, iff);
2963 register_node(proj2, loop, iff, ddepth);
2964
2965 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2966 register_node(cmp, loop, proj2, ddepth);
2967
2968 BoolNode* bol = new BoolNode(cmp, relop);
2969 register_node(bol, loop, proj2, ddepth);
2970
2971 int opcode = iff->Opcode();
2972 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2973 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2974 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2975 register_node(new_if, loop, proj2, ddepth);
2976
2977 proj->set_req(0, new_if); // reattach
2978 set_idom(proj, new_if, ddepth);
2979
2980 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2981 guarantee(new_exit != nullptr, "null exit node");
2982 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2983
2984 return new_exit;
2985 }
2986
2987 //------------------------------ insert_region_before_proj -------------------------------------
2988 // Insert a region before an if projection (* - new node)
2989 //
2990 // before
2991 // if(test)
2992 // / |
2993 // v |
2994 // proj v
2995 // other-proj
2996 //
2997 // after
2998 // if(test)
2999 // / |
3000 // v |
3001 // * proj-clone v
3002 // | other-proj
3003 // v
3004 // * new-region
3005 // |
3006 // v
3007 // * dum_if
3008 // / \
3009 // v \
3010 // * dum-proj v
3011 // proj
3012 //
3013 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3014 IfNode* iff = proj->in(0)->as_If();
3015 IdealLoopTree *loop = get_loop(proj);
3016 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3017 int ddepth = dom_depth(proj);
3018
3019 _igvn.rehash_node_delayed(iff);
3020 _igvn.rehash_node_delayed(proj);
3021
3022 proj->set_req(0, nullptr); // temporary disconnect
3023 ProjNode* proj2 = proj_clone(proj, iff);
3024 register_node(proj2, loop, iff, ddepth);
3025
3026 RegionNode* reg = new RegionNode(2);
3027 reg->set_req(1, proj2);
3028 register_node(reg, loop, iff, ddepth);
3029
3030 IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3031 register_node(dum_if, loop, reg, ddepth);
3032
3033 proj->set_req(0, dum_if); // reattach
3034 set_idom(proj, dum_if, ddepth);
3035
3036 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3037 register_node(dum_proj, loop, dum_if, ddepth);
3038
3039 return reg;
3040 }
3041
3042 //------------------------------ insert_cmpi_loop_exit -------------------------------------
3043 // Clone a signed compare loop exit from an unsigned compare and
3044 // insert it before the unsigned cmp on the stay-in-loop path.
3045 // All new nodes inserted in the dominator tree between the original
3046 // if and it's projections. The original if test is replaced with
3047 // a constant to force the stay-in-loop path.
3048 //
3049 // This is done to make sure that the original if and it's projections
3050 // still dominate the same set of control nodes, that the ctrl() relation
3051 // from data nodes to them is preserved, and that their loop nesting is
3052 // preserved.
3053 //
3054 // before
3055 // if(i <u limit) unsigned compare loop exit
3056 // / |
3057 // v v
3058 // exit-proj stay-in-loop-proj
3059 //
3060 // after
3061 // if(stay-in-loop-const) original if
3062 // / |
3063 // / v
3064 // / if(i < limit) new signed test
3065 // / / |
3066 // / / v
3067 // / / if(i <u limit) new cloned unsigned test
3068 // / / / |
3069 // v v v |
3070 // region |
3071 // | |
3072 // dum-if |
3073 // / | |
3074 // ether | |
3075 // v v
3076 // exit-proj stay-in-loop-proj
3077 //
3078 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
3079 const bool Signed = true;
3080 const bool Unsigned = false;
3081
3082 BoolNode* bol = if_cmpu->in(1)->as_Bool();
3083 if (bol->_test._test != BoolTest::lt) return nullptr;
3084 CmpNode* cmpu = bol->in(1)->as_Cmp();
3085 if (cmpu->Opcode() != Op_CmpU) return nullptr;
3086 int stride = stride_of_possible_iv(if_cmpu);
3087 if (stride == 0) return nullptr;
3088
3089 Node* lp_proj = stay_in_loop(if_cmpu, loop);
3090 guarantee(lp_proj != nullptr, "null loop node");
3091
3092 ProjNode* lp_continue = lp_proj->as_Proj();
3093 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3094 if (!lp_exit->is_IfFalse()) {
3095 // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3096 // We therefore can't add a single exit condition.
3097 return nullptr;
3098 }
3099 // The loop exit condition is !(i <u limit) ==> (i < 0 || i >= limit).
3100 // Split out the exit condition (i < 0) for stride < 0 or (i >= limit) for stride > 0.
3101 Node* limit = nullptr;
3102 if (stride > 0) {
3103 limit = cmpu->in(2);
3104 } else {
3105 limit = _igvn.makecon(TypeInt::ZERO);
3106 set_ctrl(limit, C->root());
3107 }
3108 // Create a new region on the exit path
3109 RegionNode* reg = insert_region_before_proj(lp_exit);
3110 guarantee(reg != nullptr, "null region node");
3111
3112 // Clone the if-cmpu-true-false using a signed compare
3113 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3114 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
3115 reg->add_req(cmpi_exit);
3116
3117 // Clone the if-cmpu-true-false
3118 BoolTest::mask rel_u = bol->_test._test;
3119 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3120 reg->add_req(cmpu_exit);
3121
3122 // Force original if to stay in loop.
3123 short_circuit_if(if_cmpu, lp_continue);
3124
3125 return cmpi_exit->in(0)->as_If();
3126 }
3127
3128 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3129 // Remove a previously inserted signed compare loop exit.
3130 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3131 Node* lp_proj = stay_in_loop(if_cmp, loop);
3132 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3133 stay_in_loop(lp_proj, loop)->is_If() &&
3134 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3135 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3136 set_ctrl(con, C->root());
3137 if_cmp->set_req(1, con);
3138 }
3139
3140 //------------------------------ scheduled_nodelist -------------------------------------
3141 // Create a post order schedule of nodes that are in the
3142 // "member" set. The list is returned in "sched".
3143 // The first node in "sched" is the loop head, followed by
3144 // nodes which have no inputs in the "member" set, and then
3145 // followed by the nodes that have an immediate input dependence
3146 // on a node in "sched".
3147 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3148
3149 assert(member.test(loop->_head->_idx), "loop head must be in member set");
3150 VectorSet visited;
3151 Node_Stack nstack(loop->_body.size());
3152
3153 Node* n = loop->_head; // top of stack is cached in "n"
3154 uint idx = 0;
3155 visited.set(n->_idx);
3156
3157 // Initially push all with no inputs from within member set
3158 for(uint i = 0; i < loop->_body.size(); i++ ) {
3159 Node *elt = loop->_body.at(i);
3160 if (member.test(elt->_idx)) {
3161 bool found = false;
3162 for (uint j = 0; j < elt->req(); j++) {
3163 Node* def = elt->in(j);
3164 if (def && member.test(def->_idx) && def != elt) {
3165 found = true;
3166 break;
3167 }
3168 }
3169 if (!found && elt != loop->_head) {
3170 nstack.push(n, idx);
3171 n = elt;
3172 assert(!visited.test(n->_idx), "not seen yet");
3173 visited.set(n->_idx);
3174 }
3175 }
3176 }
3177
3178 // traverse out's that are in the member set
3179 while (true) {
3180 if (idx < n->outcnt()) {
3181 Node* use = n->raw_out(idx);
3182 idx++;
3183 if (!visited.test_set(use->_idx)) {
3184 if (member.test(use->_idx)) {
3185 nstack.push(n, idx);
3186 n = use;
3187 idx = 0;
3188 }
3189 }
3190 } else {
3191 // All outputs processed
3192 sched.push(n);
3193 if (nstack.is_empty()) break;
3194 n = nstack.node();
3195 idx = nstack.index();
3196 nstack.pop();
3197 }
3198 }
3199 }
3200
3201
3202 //------------------------------ has_use_in_set -------------------------------------
3203 // Has a use in the vector set
3204 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3205 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3206 Node* use = n->fast_out(j);
3207 if (vset.test(use->_idx)) {
3208 return true;
3209 }
3210 }
3211 return false;
3212 }
3213
3214
3215 //------------------------------ has_use_internal_to_set -------------------------------------
3216 // Has use internal to the vector set (ie. not in a phi at the loop head)
3217 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3218 Node* head = loop->_head;
3219 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3220 Node* use = n->fast_out(j);
3221 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3222 return true;
3223 }
3224 }
3225 return false;
3226 }
3227
3228
3229 //------------------------------ clone_for_use_outside_loop -------------------------------------
3230 // clone "n" for uses that are outside of loop
3231 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3232 int cloned = 0;
3233 assert(worklist.size() == 0, "should be empty");
3234 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3235 Node* use = n->fast_out(j);
3236 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3237 worklist.push(use);
3238 }
3239 }
3240
3241 if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3242 "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3243 return -1;
3244 }
3245
3246 while( worklist.size() ) {
3247 Node *use = worklist.pop();
3248 if (!has_node(use) || use->in(0) == C->top()) continue;
3249 uint j;
3250 for (j = 0; j < use->req(); j++) {
3251 if (use->in(j) == n) break;
3252 }
3253 assert(j < use->req(), "must be there");
3254
3255 // clone "n" and insert it between the inputs of "n" and the use outside the loop
3256 Node* n_clone = n->clone();
3257 _igvn.replace_input_of(use, j, n_clone);
3258 cloned++;
3259 Node* use_c;
3260 if (!use->is_Phi()) {
3261 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3262 } else {
3263 // Use in a phi is considered a use in the associated predecessor block
3264 use_c = use->in(0)->in(j);
3265 }
3266 set_ctrl(n_clone, use_c);
3267 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3268 get_loop(use_c)->_body.push(n_clone);
3269 _igvn.register_new_node_with_optimizer(n_clone);
3270 #ifndef PRODUCT
3271 if (TracePartialPeeling) {
3272 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3273 }
3274 #endif
3275 }
3276 return cloned;
3277 }
3278
3279
3280 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3281 // clone "n" for special uses that are in the not_peeled region.
3282 // If these def-uses occur in separate blocks, the code generator
3283 // marks the method as not compilable. For example, if a "BoolNode"
3284 // is in a different basic block than the "IfNode" that uses it, then
3285 // the compilation is aborted in the code generator.
3286 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3287 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3288 if (n->is_Phi() || n->is_Load()) {
3289 return;
3290 }
3291 assert(worklist.size() == 0, "should be empty");
3292 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3293 Node* use = n->fast_out(j);
3294 if ( not_peel.test(use->_idx) &&
3295 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
3296 use->in(1) == n) {
3297 worklist.push(use);
3298 }
3299 }
3300 if (worklist.size() > 0) {
3301 // clone "n" and insert it between inputs of "n" and the use
3302 Node* n_clone = n->clone();
3303 loop->_body.push(n_clone);
3304 _igvn.register_new_node_with_optimizer(n_clone);
3305 set_ctrl(n_clone, get_ctrl(n));
3306 sink_list.push(n_clone);
3307 not_peel.set(n_clone->_idx);
3308 #ifndef PRODUCT
3309 if (TracePartialPeeling) {
3310 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3311 }
3312 #endif
3313 while( worklist.size() ) {
3314 Node *use = worklist.pop();
3315 _igvn.rehash_node_delayed(use);
3316 for (uint j = 1; j < use->req(); j++) {
3317 if (use->in(j) == n) {
3318 use->set_req(j, n_clone);
3319 }
3320 }
3321 }
3322 }
3323 }
3324
3325
3326 //------------------------------ insert_phi_for_loop -------------------------------------
3327 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3328 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3329 Node *phi = PhiNode::make(lp, back_edge_val);
3330 phi->set_req(LoopNode::EntryControl, lp_entry_val);
3331 // Use existing phi if it already exists
3332 Node *hit = _igvn.hash_find_insert(phi);
3333 if( hit == nullptr ) {
3334 _igvn.register_new_node_with_optimizer(phi);
3335 set_ctrl(phi, lp);
3336 } else {
3337 // Remove the new phi from the graph and use the hit
3338 _igvn.remove_dead_node(phi);
3339 phi = hit;
3340 }
3341 _igvn.replace_input_of(use, idx, phi);
3342 }
3343
3344 #ifdef ASSERT
3345 //------------------------------ is_valid_loop_partition -------------------------------------
3346 // Validate the loop partition sets: peel and not_peel
3347 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3348 VectorSet& not_peel ) {
3349 uint i;
3350 // Check that peel_list entries are in the peel set
3351 for (i = 0; i < peel_list.size(); i++) {
3352 if (!peel.test(peel_list.at(i)->_idx)) {
3353 return false;
3354 }
3355 }
3356 // Check at loop members are in one of peel set or not_peel set
3357 for (i = 0; i < loop->_body.size(); i++ ) {
3358 Node *def = loop->_body.at(i);
3359 uint di = def->_idx;
3360 // Check that peel set elements are in peel_list
3361 if (peel.test(di)) {
3362 if (not_peel.test(di)) {
3363 return false;
3364 }
3365 // Must be in peel_list also
3366 bool found = false;
3367 for (uint j = 0; j < peel_list.size(); j++) {
3368 if (peel_list.at(j)->_idx == di) {
3369 found = true;
3370 break;
3371 }
3372 }
3373 if (!found) {
3374 return false;
3375 }
3376 } else if (not_peel.test(di)) {
3377 if (peel.test(di)) {
3378 return false;
3379 }
3380 } else {
3381 return false;
3382 }
3383 }
3384 return true;
3385 }
3386
3387 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3388 // Ensure a use outside of loop is of the right form
3389 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3390 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3391 return (use->is_Phi() &&
3392 use_c->is_Region() && use_c->req() == 3 &&
3393 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3394 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3395 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3396 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3397 }
3398
3399 //------------------------------ is_valid_clone_loop_form -------------------------------------
3400 // Ensure that all uses outside of loop are of the right form
3401 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3402 uint orig_exit_idx, uint clone_exit_idx) {
3403 uint len = peel_list.size();
3404 for (uint i = 0; i < len; i++) {
3405 Node *def = peel_list.at(i);
3406
3407 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3408 Node *use = def->fast_out(j);
3409 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3410 if (!loop->is_member(get_loop(use_c))) {
3411 // use is not in the loop, check for correct structure
3412 if (use->in(0) == def) {
3413 // Okay
3414 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3415 return false;
3416 }
3417 }
3418 }
3419 }
3420 return true;
3421 }
3422 #endif
3423
3424 //------------------------------ partial_peel -------------------------------------
3425 // Partially peel (aka loop rotation) the top portion of a loop (called
3426 // the peel section below) by cloning it and placing one copy just before
3427 // the new loop head and the other copy at the bottom of the new loop.
3428 //
3429 // before after where it came from
3430 //
3431 // stmt1 stmt1
3432 // loop: stmt2 clone
3433 // stmt2 if condA goto exitA clone
3434 // if condA goto exitA new_loop: new
3435 // stmt3 stmt3 clone
3436 // if !condB goto loop if condB goto exitB clone
3437 // exitB: stmt2 orig
3438 // stmt4 if !condA goto new_loop orig
3439 // exitA: goto exitA
3440 // exitB:
3441 // stmt4
3442 // exitA:
3443 //
3444 // Step 1: find the cut point: an exit test on probable
3445 // induction variable.
3446 // Step 2: schedule (with cloning) operations in the peel
3447 // section that can be executed after the cut into
3448 // the section that is not peeled. This may need
3449 // to clone operations into exit blocks. For
3450 // instance, a reference to A[i] in the not-peel
3451 // section and a reference to B[i] in an exit block
3452 // may cause a left-shift of i by 2 to be placed
3453 // in the peel block. This step will clone the left
3454 // shift into the exit block and sink the left shift
3455 // from the peel to the not-peel section.
3456 // Step 3: clone the loop, retarget the control, and insert
3457 // phis for values that are live across the new loop
3458 // head. This is very dependent on the graph structure
3459 // from clone_loop. It creates region nodes for
3460 // exit control and associated phi nodes for values
3461 // flow out of the loop through that exit. The region
3462 // node is dominated by the clone's control projection.
3463 // So the clone's peel section is placed before the
3464 // new loop head, and the clone's not-peel section is
3465 // forms the top part of the new loop. The original
3466 // peel section forms the tail of the new loop.
3467 // Step 4: update the dominator tree and recompute the
3468 // dominator depth.
3469 //
3470 // orig
3471 //
3472 // stmt1
3473 // |
3474 // v
3475 // loop predicate
3476 // |
3477 // v
3478 // loop<----+
3479 // | |
3480 // stmt2 |
3481 // | |
3482 // v |
3483 // ifA |
3484 // / | |
3485 // v v |
3486 // false true ^ <-- last_peel
3487 // / | |
3488 // / ===|==cut |
3489 // / stmt3 | <-- first_not_peel
3490 // / | |
3491 // | v |
3492 // v ifB |
3493 // exitA: / \ |
3494 // / \ |
3495 // v v |
3496 // false true |
3497 // / \ |
3498 // / ----+
3499 // |
3500 // v
3501 // exitB:
3502 // stmt4
3503 //
3504 //
3505 // after clone loop
3506 //
3507 // stmt1
3508 // |
3509 // v
3510 // loop predicate
3511 // / \
3512 // clone / \ orig
3513 // / \
3514 // / \
3515 // v v
3516 // +---->loop loop<----+
3517 // | | | |
3518 // | stmt2 stmt2 |
3519 // | | | |
3520 // | v v |
3521 // | ifA ifA |
3522 // | | \ / | |
3523 // | v v v v |
3524 // ^ true false false true ^ <-- last_peel
3525 // | | ^ \ / | |
3526 // | cut==|== \ \ / ===|==cut |
3527 // | stmt3 \ \ / stmt3 | <-- first_not_peel
3528 // | | dom | | | |
3529 // | v \ 1v v2 v |
3530 // | ifB regionA ifB |
3531 // | / \ | / \ |
3532 // | / \ v / \ |
3533 // | v v exitA: v v |
3534 // | true false false true |
3535 // | / ^ \ / \ |
3536 // +---- \ \ / ----+
3537 // dom \ /
3538 // \ 1v v2
3539 // regionB
3540 // |
3541 // v
3542 // exitB:
3543 // stmt4
3544 //
3545 //
3546 // after partial peel
3547 //
3548 // stmt1
3549 // |
3550 // v
3551 // loop predicate
3552 // /
3553 // clone / orig
3554 // / TOP
3555 // / \
3556 // v v
3557 // TOP->loop loop----+
3558 // | | |
3559 // stmt2 stmt2 |
3560 // | | |
3561 // v v |
3562 // ifA ifA |
3563 // | \ / | |
3564 // v v v v |
3565 // true false false true | <-- last_peel
3566 // | ^ \ / +------|---+
3567 // +->newloop \ \ / === ==cut | |
3568 // | stmt3 \ \ / TOP | |
3569 // | | dom | | stmt3 | | <-- first_not_peel
3570 // | v \ 1v v2 v | |
3571 // | ifB regionA ifB ^ v
3572 // | / \ | / \ | |
3573 // | / \ v / \ | |
3574 // | v v exitA: v v | |
3575 // | true false false true | |
3576 // | / ^ \ / \ | |
3577 // | | \ \ / v | |
3578 // | | dom \ / TOP | |
3579 // | | \ 1v v2 | |
3580 // ^ v regionB | |
3581 // | | | | |
3582 // | | v ^ v
3583 // | | exitB: | |
3584 // | | stmt4 | |
3585 // | +------------>-----------------+ |
3586 // | |
3587 // +-----------------<---------------------+
3588 //
3589 //
3590 // final graph
3591 //
3592 // stmt1
3593 // |
3594 // v
3595 // loop predicate
3596 // |
3597 // v
3598 // stmt2 clone
3599 // |
3600 // v
3601 // ........> ifA clone
3602 // : / |
3603 // dom / |
3604 // : v v
3605 // : false true
3606 // : | |
3607 // : | v
3608 // : | newloop<-----+
3609 // : | | |
3610 // : | stmt3 clone |
3611 // : | | |
3612 // : | v |
3613 // : | ifB |
3614 // : | / \ |
3615 // : | v v |
3616 // : | false true |
3617 // : | | | |
3618 // : | v stmt2 |
3619 // : | exitB: | |
3620 // : | stmt4 v |
3621 // : | ifA orig |
3622 // : | / \ |
3623 // : | / \ |
3624 // : | v v |
3625 // : | false true |
3626 // : | / \ |
3627 // : v v -----+
3628 // RegionA
3629 // |
3630 // v
3631 // exitA
3632 //
3633 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3634
3635 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3636 if (!loop->_head->is_Loop()) {
3637 return false;
3638 }
3639 LoopNode *head = loop->_head->as_Loop();
3640
3641 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3642 return false;
3643 }
3644
3645 // Check for complex exit control
3646 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3647 Node *n = loop->_body.at(ii);
3648 int opc = n->Opcode();
3649 if (n->is_Call() ||
3650 opc == Op_Catch ||
3651 opc == Op_CatchProj ||
3652 opc == Op_Jump ||
3653 opc == Op_JumpProj) {
3654 #ifndef PRODUCT
3655 if (TracePartialPeeling) {
3656 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3657 }
3658 #endif
3659 return false;
3660 }
3661 }
3662
3663 int dd = dom_depth(head);
3664
3665 // Step 1: find cut point
3666
3667 // Walk up dominators to loop head looking for first loop exit
3668 // which is executed on every path thru loop.
3669 IfNode *peel_if = nullptr;
3670 IfNode *peel_if_cmpu = nullptr;
3671
3672 Node *iff = loop->tail();
3673 while (iff != head) {
3674 if (iff->is_If()) {
3675 Node *ctrl = get_ctrl(iff->in(1));
3676 if (ctrl->is_top()) return false; // Dead test on live IF.
3677 // If loop-varying exit-test, check for induction variable
3678 if (loop->is_member(get_loop(ctrl)) &&
3679 loop->is_loop_exit(iff) &&
3680 is_possible_iv_test(iff)) {
3681 Node* cmp = iff->in(1)->in(1);
3682 if (cmp->Opcode() == Op_CmpI) {
3683 peel_if = iff->as_If();
3684 } else {
3685 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3686 peel_if_cmpu = iff->as_If();
3687 }
3688 }
3689 }
3690 iff = idom(iff);
3691 }
3692
3693 // Prefer signed compare over unsigned compare.
3694 IfNode* new_peel_if = nullptr;
3695 if (peel_if == nullptr) {
3696 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
3697 return false; // No peel point found
3698 }
3699 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3700 if (new_peel_if == nullptr) {
3701 return false; // No peel point found
3702 }
3703 peel_if = new_peel_if;
3704 }
3705 Node* last_peel = stay_in_loop(peel_if, loop);
3706 Node* first_not_peeled = stay_in_loop(last_peel, loop);
3707 if (first_not_peeled == nullptr || first_not_peeled == head) {
3708 return false;
3709 }
3710
3711 #ifndef PRODUCT
3712 if (TraceLoopOpts) {
3713 tty->print("PartialPeel ");
3714 loop->dump_head();
3715 }
3716
3717 if (TracePartialPeeling) {
3718 tty->print_cr("before partial peel one iteration");
3719 Node_List wl;
3720 Node* t = head->in(2);
3721 while (true) {
3722 wl.push(t);
3723 if (t == head) break;
3724 t = idom(t);
3725 }
3726 while (wl.size() > 0) {
3727 Node* tt = wl.pop();
3728 tt->dump();
3729 if (tt == last_peel) tty->print_cr("-- cut --");
3730 }
3731 }
3732 #endif
3733 VectorSet peel;
3734 VectorSet not_peel;
3735 Node_List peel_list;
3736 Node_List worklist;
3737 Node_List sink_list;
3738
3739 uint estimate = loop->est_loop_clone_sz(1);
3740 if (exceeding_node_budget(estimate)) {
3741 return false;
3742 }
3743
3744 // Set of cfg nodes to peel are those that are executable from
3745 // the head through last_peel.
3746 assert(worklist.size() == 0, "should be empty");
3747 worklist.push(head);
3748 peel.set(head->_idx);
3749 while (worklist.size() > 0) {
3750 Node *n = worklist.pop();
3751 if (n != last_peel) {
3752 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3753 Node* use = n->fast_out(j);
3754 if (use->is_CFG() &&
3755 loop->is_member(get_loop(use)) &&
3756 !peel.test_set(use->_idx)) {
3757 worklist.push(use);
3758 }
3759 }
3760 }
3761 }
3762
3763 // Set of non-cfg nodes to peel are those that are control
3764 // dependent on the cfg nodes.
3765 for (uint i = 0; i < loop->_body.size(); i++) {
3766 Node *n = loop->_body.at(i);
3767 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3768 if (peel.test(n_c->_idx)) {
3769 peel.set(n->_idx);
3770 } else {
3771 not_peel.set(n->_idx);
3772 }
3773 }
3774
3775 // Step 2: move operations from the peeled section down into the
3776 // not-peeled section
3777
3778 // Get a post order schedule of nodes in the peel region
3779 // Result in right-most operand.
3780 scheduled_nodelist(loop, peel, peel_list);
3781
3782 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3783
3784 // For future check for too many new phis
3785 uint old_phi_cnt = 0;
3786 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3787 Node* use = head->fast_out(j);
3788 if (use->is_Phi()) old_phi_cnt++;
3789 }
3790
3791 #ifndef PRODUCT
3792 if (TracePartialPeeling) {
3793 tty->print_cr("\npeeled list");
3794 }
3795 #endif
3796
3797 // Evacuate nodes in peel region into the not_peeled region if possible
3798 bool too_many_clones = false;
3799 uint new_phi_cnt = 0;
3800 uint cloned_for_outside_use = 0;
3801 for (uint i = 0; i < peel_list.size();) {
3802 Node* n = peel_list.at(i);
3803 #ifndef PRODUCT
3804 if (TracePartialPeeling) n->dump();
3805 #endif
3806 bool incr = true;
3807 if (!n->is_CFG()) {
3808 if (has_use_in_set(n, not_peel)) {
3809 // If not used internal to the peeled region,
3810 // move "n" from peeled to not_peeled region.
3811 if (!has_use_internal_to_set(n, peel, loop)) {
3812 // if not pinned and not a load (which maybe anti-dependent on a store)
3813 // and not a CMove (Matcher expects only bool->cmove).
3814 if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
3815 int new_clones = clone_for_use_outside_loop(loop, n, worklist);
3816 if (new_clones == -1) {
3817 too_many_clones = true;
3818 break;
3819 }
3820 cloned_for_outside_use += new_clones;
3821 sink_list.push(n);
3822 peel.remove(n->_idx);
3823 not_peel.set(n->_idx);
3824 peel_list.remove(i);
3825 incr = false;
3826 #ifndef PRODUCT
3827 if (TracePartialPeeling) {
3828 tty->print_cr("sink to not_peeled region: %d newbb: %d",
3829 n->_idx, get_ctrl(n)->_idx);
3830 }
3831 #endif
3832 }
3833 } else {
3834 // Otherwise check for special def-use cases that span
3835 // the peel/not_peel boundary such as bool->if
3836 clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3837 new_phi_cnt++;
3838 }
3839 }
3840 }
3841 if (incr) i++;
3842 }
3843
3844 estimate += cloned_for_outside_use + new_phi_cnt;
3845 bool exceed_node_budget = !may_require_nodes(estimate);
3846 bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3847
3848 if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
3849 #ifndef PRODUCT
3850 if (TracePartialPeeling && exceed_phi_limit) {
3851 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
3852 new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
3853 }
3854 #endif
3855 if (new_peel_if != nullptr) {
3856 remove_cmpi_loop_exit(new_peel_if, loop);
3857 }
3858 // Inhibit more partial peeling on this loop
3859 assert(!head->is_partial_peel_loop(), "not partial peeled");
3860 head->mark_partial_peel_failed();
3861 if (cloned_for_outside_use > 0) {
3862 // Terminate this round of loop opts because
3863 // the graph outside this loop was changed.
3864 C->set_major_progress();
3865 return true;
3866 }
3867 return false;
3868 }
3869
3870 // Step 3: clone loop, retarget control, and insert new phis
3871
3872 // Create new loop head for new phis and to hang
3873 // the nodes being moved (sinked) from the peel region.
3874 LoopNode* new_head = new LoopNode(last_peel, last_peel);
3875 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3876 _igvn.register_new_node_with_optimizer(new_head);
3877 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3878 _igvn.replace_input_of(first_not_peeled, 0, new_head);
3879 set_loop(new_head, loop);
3880 loop->_body.push(new_head);
3881 not_peel.set(new_head->_idx);
3882 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3883 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3884
3885 while (sink_list.size() > 0) {
3886 Node* n = sink_list.pop();
3887 set_ctrl(n, new_head);
3888 }
3889
3890 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3891
3892 clone_loop(loop, old_new, dd, IgnoreStripMined);
3893
3894 const uint clone_exit_idx = 1;
3895 const uint orig_exit_idx = 2;
3896 assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
3897
3898 Node* head_clone = old_new[head->_idx];
3899 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
3900 Node* orig_tail_clone = head_clone->in(2);
3901
3902 // Add phi if "def" node is in peel set and "use" is not
3903
3904 for (uint i = 0; i < peel_list.size(); i++) {
3905 Node *def = peel_list.at(i);
3906 if (!def->is_CFG()) {
3907 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3908 Node *use = def->fast_out(j);
3909 if (has_node(use) && use->in(0) != C->top() &&
3910 (!peel.test(use->_idx) ||
3911 (use->is_Phi() && use->in(0) == head)) ) {
3912 worklist.push(use);
3913 }
3914 }
3915 while( worklist.size() ) {
3916 Node *use = worklist.pop();
3917 for (uint j = 1; j < use->req(); j++) {
3918 Node* n = use->in(j);
3919 if (n == def) {
3920
3921 // "def" is in peel set, "use" is not in peel set
3922 // or "use" is in the entry boundary (a phi) of the peel set
3923
3924 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3925
3926 if ( loop->is_member(get_loop( use_c )) ) {
3927 // use is in loop
3928 if (old_new[use->_idx] != nullptr) { // null for dead code
3929 Node* use_clone = old_new[use->_idx];
3930 _igvn.replace_input_of(use, j, C->top());
3931 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3932 }
3933 } else {
3934 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3935 // use is not in the loop, check if the live range includes the cut
3936 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3937 if (not_peel.test(lp_if->_idx)) {
3938 assert(j == orig_exit_idx, "use from original loop");
3939 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3940 }
3941 }
3942 }
3943 }
3944 }
3945 }
3946 }
3947
3948 // Step 3b: retarget control
3949
3950 // Redirect control to the new loop head if a cloned node in
3951 // the not_peeled region has control that points into the peeled region.
3952 // This necessary because the cloned peeled region will be outside
3953 // the loop.
3954 // from to
3955 // cloned-peeled <---+
3956 // new_head_clone: | <--+
3957 // cloned-not_peeled in(0) in(0)
3958 // orig-peeled
3959
3960 for (uint i = 0; i < loop->_body.size(); i++) {
3961 Node *n = loop->_body.at(i);
3962 if (!n->is_CFG() && n->in(0) != nullptr &&
3963 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3964 Node* n_clone = old_new[n->_idx];
3965 _igvn.replace_input_of(n_clone, 0, new_head_clone);
3966 }
3967 }
3968
3969 // Backedge of the surviving new_head (the clone) is original last_peel
3970 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3971
3972 // Cut first node in original not_peel set
3973 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
3974 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
3975 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
3976
3977 // Copy head_clone back-branch info to original head
3978 // and remove original head's loop entry and
3979 // clone head's back-branch
3980 _igvn.rehash_node_delayed(head); // Multiple edge updates
3981 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
3982 head->set_req(LoopNode::LoopBackControl, C->top());
3983 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3984
3985 // Similarly modify the phis
3986 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3987 Node* use = head->fast_out(k);
3988 if (use->is_Phi() && use->outcnt() > 0) {
3989 Node* use_clone = old_new[use->_idx];
3990 _igvn.rehash_node_delayed(use); // Multiple edge updates
3991 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
3992 use->set_req(LoopNode::LoopBackControl, C->top());
3993 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3994 }
3995 }
3996
3997 // Step 4: update dominator tree and dominator depth
3998
3999 set_idom(head, orig_tail_clone, dd);
4000 recompute_dom_depth();
4001
4002 // Inhibit more partial peeling on this loop
4003 new_head_clone->set_partial_peel_loop();
4004 C->set_major_progress();
4005 loop->record_for_igvn();
4006
4007 #ifndef PRODUCT
4008 if (TracePartialPeeling) {
4009 tty->print_cr("\nafter partial peel one iteration");
4010 Node_List wl;
4011 Node* t = last_peel;
4012 while (true) {
4013 wl.push(t);
4014 if (t == head_clone) break;
4015 t = idom(t);
4016 }
4017 while (wl.size() > 0) {
4018 Node* tt = wl.pop();
4019 if (tt == head) tty->print_cr("orig head");
4020 else if (tt == new_head_clone) tty->print_cr("new head");
4021 else if (tt == head_clone) tty->print_cr("clone head");
4022 tt->dump();
4023 }
4024 }
4025 #endif
4026 return true;
4027 }
4028
4029 // Transform:
4030 //
4031 // loop<-----------------+
4032 // | |
4033 // stmt1 stmt2 .. stmtn |
4034 // | | | |
4035 // \ | / |
4036 // v v v |
4037 // region |
4038 // | |
4039 // shared_stmt |
4040 // | |
4041 // v |
4042 // if |
4043 // / \ |
4044 // | -----------+
4045 // v
4046 //
4047 // into:
4048 //
4049 // loop<-------------------+
4050 // | |
4051 // v |
4052 // +->loop |
4053 // | | |
4054 // | stmt1 stmt2 .. stmtn |
4055 // | | | | |
4056 // | | \ / |
4057 // | | v v |
4058 // | | region1 |
4059 // | | | |
4060 // | shared_stmt shared_stmt |
4061 // | | | |
4062 // | v v |
4063 // | if if |
4064 // | /\ / \ |
4065 // +-- | | -------+
4066 // \ /
4067 // v v
4068 // region2
4069 //
4070 // (region2 is shown to merge mirrored projections of the loop exit
4071 // ifs to make the diagram clearer but they really merge the same
4072 // projection)
4073 //
4074 // Conditions for this transformation to trigger:
4075 // - the path through stmt1 is frequent enough
4076 // - the inner loop will be turned into a counted loop after transformation
4077 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4078 if (!DuplicateBackedge) {
4079 return false;
4080 }
4081 assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4082 if (!loop->_head->is_Loop()) {
4083 return false;
4084 }
4085
4086 uint estimate = loop->est_loop_clone_sz(1);
4087 if (exceeding_node_budget(estimate)) {
4088 return false;
4089 }
4090
4091 LoopNode *head = loop->_head->as_Loop();
4092
4093 Node* region = nullptr;
4094 IfNode* exit_test = nullptr;
4095 uint inner;
4096 float f;
4097 if (StressDuplicateBackedge) {
4098 if (head->is_strip_mined()) {
4099 return false;
4100 }
4101 Node* c = head->in(LoopNode::LoopBackControl);
4102
4103 while (c != head) {
4104 if (c->is_Region()) {
4105 region = c;
4106 }
4107 c = idom(c);
4108 }
4109
4110 if (region == nullptr) {
4111 return false;
4112 }
4113
4114 inner = 1;
4115 } else {
4116 // Is the shape of the loop that of a counted loop...
4117 Node* back_control = loop_exit_control(head, loop);
4118 if (back_control == nullptr) {
4119 return false;
4120 }
4121
4122 BoolTest::mask bt = BoolTest::illegal;
4123 float cl_prob = 0;
4124 Node* incr = nullptr;
4125 Node* limit = nullptr;
4126 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4127 if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4128 return false;
4129 }
4130
4131 // With an extra phi for the candidate iv?
4132 // Or the region node is the loop head
4133 if (!incr->is_Phi() || incr->in(0) == head) {
4134 return false;
4135 }
4136
4137 PathFrequency pf(head, this);
4138 region = incr->in(0);
4139
4140 // Go over all paths for the extra phi's region and see if that
4141 // path is frequent enough and would match the expected iv shape
4142 // if the extra phi is removed
4143 inner = 0;
4144 for (uint i = 1; i < incr->req(); ++i) {
4145 Node* in = incr->in(i);
4146 Node* trunc1 = nullptr;
4147 Node* trunc2 = nullptr;
4148 const TypeInteger* iv_trunc_t = nullptr;
4149 Node* orig_in = in;
4150 if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4151 continue;
4152 }
4153 assert(in->Opcode() == Op_AddI, "wrong increment code");
4154 Node* xphi = nullptr;
4155 Node* stride = loop_iv_stride(in, loop, xphi);
4156
4157 if (stride == nullptr) {
4158 continue;
4159 }
4160
4161 PhiNode* phi = loop_iv_phi(xphi, nullptr, head, loop);
4162 if (phi == nullptr ||
4163 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4164 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4165 return false;
4166 }
4167
4168 f = pf.to(region->in(i));
4169 if (f > 0.5) {
4170 inner = i;
4171 break;
4172 }
4173 }
4174
4175 if (inner == 0) {
4176 return false;
4177 }
4178
4179 exit_test = back_control->in(0)->as_If();
4180 }
4181
4182 if (idom(region)->is_Catch()) {
4183 return false;
4184 }
4185
4186 // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4187 Unique_Node_List wq;
4188 wq.push(head->in(LoopNode::LoopBackControl));
4189 for (uint i = 0; i < wq.size(); i++) {
4190 Node* c = wq.at(i);
4191 assert(get_loop(c) == loop, "not in the right loop?");
4192 if (c->is_Region()) {
4193 if (c != region) {
4194 for (uint j = 1; j < c->req(); ++j) {
4195 wq.push(c->in(j));
4196 }
4197 }
4198 } else {
4199 wq.push(c->in(0));
4200 }
4201 assert(!is_dominator(c, region) || c == region, "shouldn't go above region");
4202 }
4203
4204 Node* region_dom = idom(region);
4205
4206 // Can't do the transformation if this would cause a membar pair to
4207 // be split
4208 for (uint i = 0; i < wq.size(); i++) {
4209 Node* c = wq.at(i);
4210 if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4211 assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4212 if (!wq.member(c->as_MemBar()->leading_membar())) {
4213 return false;
4214 }
4215 }
4216 }
4217
4218 // Collect data nodes that need to be clones as well
4219 int dd = dom_depth(head);
4220
4221 for (uint i = 0; i < loop->_body.size(); ++i) {
4222 Node* n = loop->_body.at(i);
4223 if (has_ctrl(n)) {
4224 Node* c = get_ctrl(n);
4225 if (wq.member(c)) {
4226 wq.push(n);
4227 }
4228 } else {
4229 set_idom(n, idom(n), dd);
4230 }
4231 }
4232
4233 // clone shared_stmt
4234 clone_loop_body(wq, old_new, nullptr);
4235
4236 Node* region_clone = old_new[region->_idx];
4237 region_clone->set_req(inner, C->top());
4238 set_idom(region, region->in(inner), dd);
4239
4240 // Prepare the outer loop
4241 Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4242 register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4243 _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4244 set_idom(head, outer_head, dd);
4245
4246 fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4247
4248 // Make one of the shared_stmt copies only reachable from stmt1, the
4249 // other only from stmt2..stmtn.
4250 Node* dom = nullptr;
4251 for (uint i = 1; i < region->req(); ++i) {
4252 if (i != inner) {
4253 _igvn.replace_input_of(region, i, C->top());
4254 }
4255 Node* in = region_clone->in(i);
4256 if (in->is_top()) {
4257 continue;
4258 }
4259 if (dom == nullptr) {
4260 dom = in;
4261 } else {
4262 dom = dom_lca(dom, in);
4263 }
4264 }
4265
4266 set_idom(region_clone, dom, dd);
4267
4268 // Set up the outer loop
4269 for (uint i = 0; i < head->outcnt(); i++) {
4270 Node* u = head->raw_out(i);
4271 if (u->is_Phi()) {
4272 Node* outer_phi = u->clone();
4273 outer_phi->set_req(0, outer_head);
4274 Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4275 if (backedge == nullptr) {
4276 backedge = u->in(LoopNode::LoopBackControl);
4277 }
4278 outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4279 register_new_node(outer_phi, outer_head);
4280 _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4281 }
4282 }
4283
4284 // create control and data nodes for out of loop uses (including region2)
4285 Node_List worklist;
4286 uint new_counter = C->unique();
4287 fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4288
4289 Node_List *split_if_set = nullptr;
4290 Node_List *split_bool_set = nullptr;
4291 Node_List *split_cex_set = nullptr;
4292 fix_data_uses(wq, loop, ControlAroundStripMined, head->is_strip_mined() ? loop->_parent : loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
4293
4294 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4295
4296 if (exit_test != nullptr) {
4297 float cnt = exit_test->_fcnt;
4298 if (cnt != COUNT_UNKNOWN) {
4299 exit_test->_fcnt = cnt * f;
4300 old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4301 }
4302 }
4303
4304 C->set_major_progress();
4305
4306 return true;
4307 }