1 /*
2 * Copyright (c) 1999, 2025, 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.
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23 */
24
25 #include "gc/shared/barrierSet.hpp"
26 #include "gc/shared/c2/barrierSetC2.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "opto/addnode.hpp"
30 #include "opto/callnode.hpp"
31 #include "opto/castnode.hpp"
32 #include "opto/connode.hpp"
33 #include "opto/divnode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/matcher.hpp"
36 #include "opto/movenode.hpp"
37 #include "opto/mulnode.hpp"
38 #include "opto/opaquenode.hpp"
39 #include "opto/rootnode.hpp"
40 #include "opto/subnode.hpp"
41 #include "opto/subtypenode.hpp"
42 #include "opto/superword.hpp"
43 #include "opto/vectornode.hpp"
44 #include "utilities/checkedCast.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 (n->Opcode() == Op_ConvL2I && n->bottom_type() != TypeInt::INT)) {
53 // ConvI2L/ConvL2I may have type information on it which is unsafe to push up
54 // so disable this for now
55 return nullptr;
56 }
57
58 // Splitting range check CastIIs through a loop induction Phi can
59 // cause new Phis to be created that are left unrelated to the loop
60 // induction Phi and prevent optimizations (vectorization)
61 if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
62 n->in(1) == region->as_CountedLoop()->phi()) {
63 return nullptr;
64 }
65
66 if (cannot_split_division(n, region)) {
67 return nullptr;
68 }
69
70 SplitThruPhiWins wins(region);
71 assert(!n->is_CFG(), "");
72 assert(region->is_Region(), "");
73
74 const Type* type = n->bottom_type();
75 const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
76 Node* phi;
77 if (t_oop != nullptr && t_oop->is_known_instance_field()) {
78 int iid = t_oop->instance_id();
79 int index = C->get_alias_index(t_oop);
80 int offset = t_oop->offset();
81 phi = new PhiNode(region, type, nullptr, iid, index, offset);
82 } else {
83 phi = PhiNode::make_blank(region, n);
84 }
85 uint old_unique = C->unique();
86 for (uint i = 1; i < region->req(); i++) {
87 Node* x;
88 Node* the_clone = nullptr;
89 if (region->in(i) == C->top()) {
90 x = C->top(); // Dead path? Use a dead data op
91 } else {
92 x = n->clone(); // Else clone up the data op
93 the_clone = x; // Remember for possible deletion.
94 // Alter data node to use pre-phi inputs
95 if (n->in(0) == region)
96 x->set_req( 0, region->in(i) );
97 for (uint j = 1; j < n->req(); j++) {
98 Node* in = n->in(j);
99 if (in->is_Phi() && in->in(0) == region)
100 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
101 }
102 }
103 // Check for a 'win' on some paths
104 const Type* t = x->Value(&_igvn);
105
106 bool singleton = t->singleton();
107
108 // A TOP singleton indicates that there are no possible values incoming
109 // along a particular edge. In most cases, this is OK, and the Phi will
110 // be eliminated later in an Ideal call. However, we can't allow this to
111 // happen if the singleton occurs on loop entry, as the elimination of
112 // the PhiNode may cause the resulting node to migrate back to a previous
113 // loop iteration.
114 if (singleton && t == Type::TOP) {
115 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
116 // irreducible loop may not be indicated by an affirmative is_Loop());
117 // therefore, the only top we can split thru a phi is on a backedge of
118 // a loop.
119 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
120 }
121
122 if (singleton) {
123 wins.add_win(i);
124 x = makecon(t);
125 } else {
126 // We now call Identity to try to simplify the cloned node.
127 // Note that some Identity methods call phase->type(this).
128 // Make sure that the type array is big enough for
129 // our new node, even though we may throw the node away.
130 // (Note: This tweaking with igvn only works because x is a new node.)
131 _igvn.set_type(x, t);
132 // If x is a TypeNode, capture any more-precise type permanently into Node
133 // otherwise it will be not updated during igvn->transform since
134 // igvn->type(x) is set to x->Value() already.
135 x->raise_bottom_type(t);
136 Node* y = x->Identity(&_igvn);
137 if (y != x) {
138 wins.add_win(i);
139 x = y;
140 } else {
141 y = _igvn.hash_find(x);
142 if (y == nullptr) {
143 y = similar_subtype_check(x, region->in(i));
144 }
145 if (y) {
146 wins.add_win(i);
147 x = y;
148 } else {
149 // Else x is a new node we are keeping
150 // We do not need register_new_node_with_optimizer
151 // because set_type has already been called.
152 _igvn._worklist.push(x);
153 }
154 }
155 }
156
157 phi->set_req( i, x );
158
159 if (the_clone == nullptr) {
160 continue;
161 }
162
163 if (the_clone != x) {
164 _igvn.remove_dead_node(the_clone);
165 } else if (region->is_Loop() && i == LoopNode::LoopBackControl &&
166 n->is_Load() && can_move_to_inner_loop(n, region->as_Loop(), x)) {
167 // it is not a win if 'x' moved from an outer to an inner loop
168 // this edge case can only happen for Load nodes
169 wins.reset();
170 break;
171 }
172 }
173 // Too few wins?
174 if (!wins.profitable(policy)) {
175 _igvn.remove_dead_node(phi);
176 return nullptr;
177 }
178
179 // Record Phi
180 register_new_node( phi, region );
181
182 for (uint i2 = 1; i2 < phi->req(); i2++) {
183 Node *x = phi->in(i2);
184 // If we commoned up the cloned 'x' with another existing Node,
185 // the existing Node picks up a new use. We need to make the
186 // existing Node occur higher up so it dominates its uses.
187 Node *old_ctrl;
188 IdealLoopTree *old_loop;
189
190 if (x->is_Con()) {
191 assert(get_ctrl(x) == C->root(), "constant control is not root");
192 continue;
193 }
194 // The occasional new node
195 if (x->_idx >= old_unique) { // Found a new, unplaced node?
196 old_ctrl = nullptr;
197 old_loop = nullptr; // Not in any prior loop
198 } else {
199 old_ctrl = get_ctrl(x);
200 old_loop = get_loop(old_ctrl); // Get prior loop
201 }
202 // New late point must dominate new use
203 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
204 if (new_ctrl == old_ctrl) // Nothing is changed
205 continue;
206
207 IdealLoopTree *new_loop = get_loop(new_ctrl);
208
209 // Don't move x into a loop if its uses are
210 // outside of loop. Otherwise x will be cloned
211 // for each use outside of this loop.
212 IdealLoopTree *use_loop = get_loop(region);
213 if (!new_loop->is_member(use_loop) &&
214 (old_loop == nullptr || !new_loop->is_member(old_loop))) {
215 // Take early control, later control will be recalculated
216 // during next iteration of loop optimizations.
217 new_ctrl = get_early_ctrl(x);
218 new_loop = get_loop(new_ctrl);
219 }
220 // Set new location
221 set_ctrl(x, new_ctrl);
222 // If changing loop bodies, see if we need to collect into new body
223 if (old_loop != new_loop) {
224 if (old_loop && !old_loop->_child)
225 old_loop->_body.yank(x);
226 if (!new_loop->_child)
227 new_loop->_body.push(x); // Collect body info
228 }
229 }
230
231 #ifndef PRODUCT
232 if (TraceLoopOpts) {
233 tty->print("Split %d %s through %d Phi in %d %s",
234 n->_idx, n->Name(), phi->_idx, region->_idx, region->Name());
235 }
236 #endif // !PRODUCT
237
238 return phi;
239 }
240
241 // Test whether node 'x' can move into an inner loop relative to node 'n'.
242 // Note: The test is not exact. Returns true if 'x' COULD end up in an inner loop,
243 // BUT it can also return true and 'x' is in the outer loop
244 bool PhaseIdealLoop::can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x) {
245 IdealLoopTree* n_loop_tree = get_loop(n_loop);
246 IdealLoopTree* x_loop_tree = get_loop(get_early_ctrl(x));
247 // x_loop_tree should be outer or same loop as n_loop_tree
248 return !x_loop_tree->is_member(n_loop_tree);
249 }
250
251 // Subtype checks that carry profile data don't common so look for a replacement by following edges
252 Node* PhaseIdealLoop::similar_subtype_check(const Node* x, Node* r_in) {
253 if (x->is_SubTypeCheck()) {
254 Node* in1 = x->in(1);
255 for (DUIterator_Fast imax, i = in1->fast_outs(imax); i < imax; i++) {
256 Node* u = in1->fast_out(i);
257 if (u != x && u->is_SubTypeCheck() && u->in(1) == x->in(1) && u->in(2) == x->in(2)) {
258 for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
259 Node* bol = u->fast_out(j);
260 for (DUIterator_Fast kmax, k = bol->fast_outs(kmax); k < kmax; k++) {
261 Node* iff = bol->fast_out(k);
262 // Only dominating subtype checks are interesting: otherwise we risk replacing a subtype check by another with
263 // unrelated profile
264 if (iff->is_If() && is_dominator(iff, r_in)) {
265 return u;
266 }
267 }
268 }
269 }
270 }
271 }
272 return nullptr;
273 }
274
275 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
276 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
277 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
278 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
279 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
280 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
281 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
282 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
283 const Type* zero;
284 switch (n->Opcode()) {
285 case Op_DivI:
286 case Op_ModI:
287 case Op_UDivI:
288 case Op_UModI:
289 zero = TypeInt::ZERO;
290 break;
291 case Op_DivL:
292 case Op_ModL:
293 case Op_UDivL:
294 case Op_UModL:
295 zero = TypeLong::ZERO;
296 break;
297 default:
298 return false;
299 }
300
301 if (n->in(0) != nullptr) {
302 // Cannot split through phi if Div or Mod node has a control dependency to a zero check.
303 return true;
304 }
305
306 Node* divisor = n->in(2);
307 return is_divisor_loop_phi(divisor, region) &&
308 loop_phi_backedge_type_contains_zero(divisor, zero);
309 }
310
311 bool PhaseIdealLoop::is_divisor_loop_phi(const Node* divisor, const Node* loop) {
312 return loop->is_Loop() && divisor->is_Phi() && divisor->in(0) == loop;
313 }
314
315 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
316 return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
317 }
318
319 //------------------------------dominated_by------------------------------------
320 // Replace the dominated test with an obvious true or false. Place it on the
321 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
322 // live path up to the dominating control.
323 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool pin_array_access_nodes) {
324 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
325
326 // prevdom is the dominating projection of the dominating test.
327 assert(iff->Opcode() == Op_If ||
328 iff->Opcode() == Op_CountedLoopEnd ||
329 iff->Opcode() == Op_LongCountedLoopEnd ||
330 iff->Opcode() == Op_RangeCheck ||
331 iff->Opcode() == Op_ParsePredicate,
332 "Check this code when new subtype is added");
333
334 int pop = prevdom->Opcode();
335 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
336 if (flip) {
337 if (pop == Op_IfTrue)
338 pop = Op_IfFalse;
339 else
340 pop = Op_IfTrue;
341 }
342 // 'con' is set to true or false to kill the dominated test.
343 Node* con = makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
344 // Hack the dominated test
345 _igvn.replace_input_of(iff, 1, con);
346
347 // If I don't have a reachable TRUE and FALSE path following the IfNode then
348 // I can assume this path reaches an infinite loop. In this case it's not
349 // important to optimize the data Nodes - either the whole compilation will
350 // be tossed or this path (and all data Nodes) will go dead.
351 if (iff->outcnt() != 2) {
352 return;
353 }
354
355 // Make control-dependent data Nodes on the live path (path that will remain
356 // once the dominated IF is removed) become control-dependent on the
357 // dominating projection.
358 Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
359
360 if (dp == nullptr) {
361 return;
362 }
363
364 rewire_safe_outputs_to_dominator(dp, prevdom, pin_array_access_nodes);
365 }
366
367 void PhaseIdealLoop::rewire_safe_outputs_to_dominator(Node* source, Node* dominator, const bool pin_array_access_nodes) {
368 IdealLoopTree* old_loop = get_loop(source);
369
370 for (DUIterator_Fast imax, i = source->fast_outs(imax); i < imax; i++) {
371 Node* out = source->fast_out(i); // Control-dependent node
372 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
373 if (out->depends_only_on_test() && _igvn.no_dependent_zero_check(out)) {
374 assert(out->in(0) == source, "must be control dependent on source");
375 _igvn.replace_input_of(out, 0, dominator);
376 if (pin_array_access_nodes) {
377 // Because of Loop Predication, Loads and range check Cast nodes that are control dependent on this range
378 // check (that is about to be removed) now depend on multiple dominating Hoisted Check Predicates. After the
379 // removal of this range check, these control dependent nodes end up at the lowest/nearest dominating predicate
380 // in the graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
381 // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the lowest
382 // dominating check.
383 Node* clone = out->pin_array_access_node();
384 if (clone != nullptr) {
385 clone = _igvn.register_new_node_with_optimizer(clone, out);
386 _igvn.replace_node(out, clone);
387 out = clone;
388 }
389 }
390 set_early_ctrl(out, false);
391 IdealLoopTree* new_loop = get_loop(get_ctrl(out));
392 if (old_loop != new_loop) {
393 if (!old_loop->_child) {
394 old_loop->_body.yank(out);
395 }
396 if (!new_loop->_child) {
397 new_loop->_body.push(out);
398 }
399 }
400 --i;
401 --imax;
402 }
403 }
404 }
405
406 //------------------------------has_local_phi_input----------------------------
407 // Return TRUE if 'n' has Phi inputs from its local block and no other
408 // block-local inputs (all non-local-phi inputs come from earlier blocks)
409 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
410 Node *n_ctrl = get_ctrl(n);
411 // See if some inputs come from a Phi in this block, or from before
412 // this block.
413 uint i;
414 for( i = 1; i < n->req(); i++ ) {
415 Node *phi = n->in(i);
416 if( phi->is_Phi() && phi->in(0) == n_ctrl )
417 break;
418 }
419 if( i >= n->req() )
420 return nullptr; // No Phi inputs; nowhere to clone thru
421
422 // Check for inputs created between 'n' and the Phi input. These
423 // must split as well; they have already been given the chance
424 // (courtesy of a post-order visit) and since they did not we must
425 // recover the 'cost' of splitting them by being very profitable
426 // when splitting 'n'. Since this is unlikely we simply give up.
427 for( i = 1; i < n->req(); i++ ) {
428 Node *m = n->in(i);
429 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
430 // We allow the special case of AddP's with no local inputs.
431 // This allows us to split-up address expressions.
432 if (m->is_AddP() &&
433 get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
434 get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
435 get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
436 // Move the AddP up to the dominating point. That's fine because control of m's inputs
437 // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
438 Node* c = find_non_split_ctrl(idom(n_ctrl));
439 if (c->is_OuterStripMinedLoop()) {
440 c->as_Loop()->verify_strip_mined(1);
441 c = c->in(LoopNode::EntryControl);
442 }
443 set_ctrl_and_loop(m, c);
444 continue;
445 }
446 return nullptr;
447 }
448 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
449 }
450
451 return n_ctrl;
452 }
453
454 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
455 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
456 assert(bt == T_INT || bt == T_LONG, "only for integers");
457 int n_op = n->Opcode();
458
459 if (n_op == Op_LShift(bt)) {
460 // Scale is loop invariant
461 Node* scale = n->in(2);
462 Node* scale_ctrl = get_ctrl(scale);
463 IdealLoopTree* scale_loop = get_loop(scale_ctrl);
464 if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
465 return nullptr;
466 }
467 const TypeInt* scale_t = scale->bottom_type()->isa_int();
468 if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
469 return nullptr; // Dont bother with byte/short masking
470 }
471 // Add must vary with loop (else shift would be loop-invariant)
472 Node* add = n->in(1);
473 Node* add_ctrl = get_ctrl(add);
474 IdealLoopTree* add_loop = get_loop(add_ctrl);
475 if (n_loop != add_loop) {
476 return nullptr; // happens w/ evil ZKM loops
477 }
478
479 // Convert I-V into I+ (0-V); same for V-I
480 if (add->Opcode() == Op_Sub(bt) &&
481 _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
482 assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
483 Node* zero = integercon(0, bt);
484 Node* neg = SubNode::make(zero, add->in(2), bt);
485 register_new_node_with_ctrl_of(neg, add->in(2));
486 add = AddNode::make(add->in(1), neg, bt);
487 register_new_node(add, add_ctrl);
488 }
489 if (add->Opcode() != Op_Add(bt)) return nullptr;
490 assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
491 // See if one add input is loop invariant
492 Node* add_var = add->in(1);
493 Node* add_var_ctrl = get_ctrl(add_var);
494 IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
495 Node* add_invar = add->in(2);
496 Node* add_invar_ctrl = get_ctrl(add_invar);
497 IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
498 if (add_invar_loop == n_loop) {
499 // Swap to find the invariant part
500 add_invar = add_var;
501 add_invar_ctrl = add_var_ctrl;
502 add_invar_loop = add_var_loop;
503 add_var = add->in(2);
504 } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
505 return nullptr;
506 }
507 if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
508 return nullptr; // No invariant part of the add?
509 }
510
511 // Yes! Reshape address expression!
512 Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
513 Node* inv_scale_ctrl =
514 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
515 add_invar_ctrl : scale_ctrl;
516 register_new_node(inv_scale, inv_scale_ctrl);
517 Node* var_scale = LShiftNode::make(add_var, scale, bt);
518 register_new_node(var_scale, n_ctrl);
519 Node* var_add = AddNode::make(var_scale, inv_scale, bt);
520 register_new_node(var_add, n_ctrl);
521 _igvn.replace_node(n, var_add);
522 return var_add;
523 }
524 return nullptr;
525 }
526
527 //------------------------------remix_address_expressions----------------------
528 // Rework addressing expressions to get the most loop-invariant stuff
529 // moved out. We'd like to do all associative operators, but it's especially
530 // important (common) to do address expressions.
531 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
532 if (!has_ctrl(n)) return nullptr;
533 Node* n_ctrl = get_ctrl(n);
534 IdealLoopTree* n_loop = get_loop(n_ctrl);
535
536 // See if 'n' mixes loop-varying and loop-invariant inputs and
537 // itself is loop-varying.
538
539 // Only interested in binary ops (and AddP)
540 if (n->req() < 3 || n->req() > 4) return nullptr;
541
542 Node* n1_ctrl = get_ctrl(n->in( 1));
543 Node* n2_ctrl = get_ctrl(n->in( 2));
544 Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
545 IdealLoopTree* n1_loop = get_loop(n1_ctrl);
546 IdealLoopTree* n2_loop = get_loop(n2_ctrl);
547 IdealLoopTree* n3_loop = get_loop(n3_ctrl);
548
549 // Does one of my inputs spin in a tighter loop than self?
550 if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
551 (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
552 (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
553 return nullptr; // Leave well enough alone
554 }
555
556 // Is at least one of my inputs loop-invariant?
557 if (n1_loop == n_loop &&
558 n2_loop == n_loop &&
559 n3_loop == n_loop) {
560 return nullptr; // No loop-invariant inputs
561 }
562
563 Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
564 if (res != nullptr) {
565 return res;
566 }
567 res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
568 if (res != nullptr) {
569 return res;
570 }
571
572 int n_op = n->Opcode();
573 // Replace (I+V) with (V+I)
574 if (n_op == Op_AddI ||
575 n_op == Op_AddL ||
576 n_op == Op_AddF ||
577 n_op == Op_AddD ||
578 n_op == Op_MulI ||
579 n_op == Op_MulL ||
580 n_op == Op_MulF ||
581 n_op == Op_MulD) {
582 if (n2_loop == n_loop) {
583 assert(n1_loop != n_loop, "");
584 n->swap_edges(1, 2);
585 }
586 }
587
588 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
589 // but not if I2 is a constant. Skip for irreducible loops.
590 if (n_op == Op_AddP && n_loop->_head->is_Loop()) {
591 if (n2_loop == n_loop && n3_loop != n_loop) {
592 if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
593 Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
594 Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
595 IdealLoopTree* n22loop = get_loop(n22_ctrl);
596 IdealLoopTree* n23_loop = get_loop(n23_ctrl);
597 if (n22loop != n_loop && n22loop->is_member(n_loop) &&
598 n23_loop == n_loop) {
599 Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
600 // Stuff new AddP in the loop preheader
601 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
602 Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
603 register_new_node(add2, n_ctrl);
604 _igvn.replace_node(n, add2);
605 return add2;
606 }
607 }
608 }
609
610 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
611 if (n2_loop != n_loop && n3_loop == n_loop) {
612 if (n->in(3)->Opcode() == Op_AddX) {
613 Node* V = n->in(3)->in(1);
614 Node* I = n->in(3)->in(2);
615 if (is_member(n_loop,get_ctrl(V))) {
616 } else {
617 Node *tmp = V; V = I; I = tmp;
618 }
619 if (!is_member(n_loop,get_ctrl(I))) {
620 Node* add1 = new AddPNode(n->in(1), n->in(2), I);
621 // Stuff new AddP in the loop preheader
622 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
623 Node* add2 = new AddPNode(n->in(1), add1, V);
624 register_new_node(add2, n_ctrl);
625 _igvn.replace_node(n, add2);
626 return add2;
627 }
628 }
629 }
630 }
631
632 return nullptr;
633 }
634
635 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
636 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
637 assert(n->Opcode() == Op_AddI, "sanity");
638 Node * nn = nullptr;
639 Node * in1 = n->in(1);
640 Node * in2 = n->in(2);
641 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
642 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
643 if (loop_n->is_counted() &&
644 loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
645 Matcher::match_rule_supported(Op_MulAddVS2VI) &&
646 Matcher::match_rule_supported(Op_MulAddS2I)) {
647 Node* mul_in1 = in1->in(1);
648 Node* mul_in2 = in1->in(2);
649 Node* mul_in3 = in2->in(1);
650 Node* mul_in4 = in2->in(2);
651 if (mul_in1->Opcode() == Op_LoadS &&
652 mul_in2->Opcode() == Op_LoadS &&
653 mul_in3->Opcode() == Op_LoadS &&
654 mul_in4->Opcode() == Op_LoadS) {
655 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
656 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
657 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
658 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
659 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
660 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
661 // All nodes should be in the same counted loop.
662 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
663 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
664 Node* adr1 = mul_in1->in(MemNode::Address);
665 Node* adr2 = mul_in2->in(MemNode::Address);
666 Node* adr3 = mul_in3->in(MemNode::Address);
667 Node* adr4 = mul_in4->in(MemNode::Address);
668 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
669 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
670 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
671 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
672 register_new_node_with_ctrl_of(nn, n);
673 _igvn.replace_node(n, nn);
674 return nn;
675 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
676 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
677 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
678 register_new_node_with_ctrl_of(nn, n);
679 _igvn.replace_node(n, nn);
680 return nn;
681 }
682 }
683 }
684 }
685 }
686 }
687 return nn;
688 }
689
690 //------------------------------conditional_move-------------------------------
691 // Attempt to replace a Phi with a conditional move. We have some pretty
692 // strict profitability requirements. All Phis at the merge point must
693 // be converted, so we can remove the control flow. We need to limit the
694 // number of c-moves to a small handful. All code that was in the side-arms
695 // of the CFG diamond is now speculatively executed. This code has to be
696 // "cheap enough". We are pretty much limited to CFG diamonds that merge
697 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
698 Node *PhaseIdealLoop::conditional_move( Node *region ) {
699
700 assert(region->is_Region(), "sanity check");
701 if (region->req() != 3) return nullptr;
702
703 // Check for CFG diamond
704 Node *lp = region->in(1);
705 Node *rp = region->in(2);
706 if (!lp || !rp) return nullptr;
707 Node *lp_c = lp->in(0);
708 if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
709 IfNode *iff = lp_c->as_If();
710
711 // Check for ops pinned in an arm of the diamond.
712 // Can't remove the control flow in this case
713 if (lp->outcnt() > 1) return nullptr;
714 if (rp->outcnt() > 1) return nullptr;
715
716 IdealLoopTree* r_loop = get_loop(region);
717 assert(r_loop == get_loop(iff), "sanity");
718 // Always convert to CMOVE if all results are used only outside this loop.
719 bool used_inside_loop = (r_loop == _ltree_root);
720
721 // Check profitability
722 int cost = 0;
723 int phis = 0;
724 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
725 Node *out = region->fast_out(i);
726 if (!out->is_Phi()) continue; // Ignore other control edges, etc
727 phis++;
728 PhiNode* phi = out->as_Phi();
729 BasicType bt = phi->type()->basic_type();
730 switch (bt) {
731 case T_DOUBLE:
732 case T_FLOAT:
733 if (C->use_cmove()) {
734 continue; //TODO: maybe we want to add some cost
735 }
736 cost += Matcher::float_cmove_cost(); // Could be very expensive
737 break;
738 case T_LONG: {
739 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
740 }
741 case T_INT: // These all CMOV fine
742 case T_ADDRESS: { // (RawPtr)
743 cost++;
744 break;
745 }
746 case T_NARROWOOP: // Fall through
747 case T_OBJECT: { // Base oops are OK, but not derived oops
748 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
749 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
750 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
751 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
752 // have a Phi for the base here that we convert to a CMOVE all is well
753 // and good. But if the base is dead, we'll not make a CMOVE. Later
754 // the allocator will have to produce a base by creating a CMOVE of the
755 // relevant bases. This puts the allocator in the business of
756 // manufacturing expensive instructions, generally a bad plan.
757 // Just Say No to Conditionally-Moved Derived Pointers.
758 if (tp && tp->offset() != 0)
759 return nullptr;
760 cost++;
761 break;
762 }
763 default:
764 return nullptr; // In particular, can't do memory or I/O
765 }
766 // Add in cost any speculative ops
767 for (uint j = 1; j < region->req(); j++) {
768 Node *proj = region->in(j);
769 Node *inp = phi->in(j);
770 if (get_ctrl(inp) == proj) { // Found local op
771 cost++;
772 // Check for a chain of dependent ops; these will all become
773 // speculative in a CMOV.
774 for (uint k = 1; k < inp->req(); k++)
775 if (get_ctrl(inp->in(k)) == proj)
776 cost += ConditionalMoveLimit; // Too much speculative goo
777 }
778 }
779 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
780 // This will likely Split-If, a higher-payoff operation.
781 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
782 Node* use = phi->fast_out(k);
783 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
784 cost += ConditionalMoveLimit;
785 // Is there a use inside the loop?
786 // Note: check only basic types since CMoveP is pinned.
787 if (!used_inside_loop && is_java_primitive(bt)) {
788 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
789 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
790 used_inside_loop = true;
791 }
792 }
793 }
794 }//for
795 Node* bol = iff->in(1);
796 assert(!bol->is_OpaqueInitializedAssertionPredicate(), "Initialized Assertion Predicates cannot form a diamond with Halt");
797 if (bol->is_OpaqueTemplateAssertionPredicate()) {
798 // Ignore Template Assertion Predicates with OpaqueTemplateAssertionPredicate nodes.
799 return nullptr;
800 }
801 if (bol->is_OpaqueMultiversioning()) {
802 assert(bol->as_OpaqueMultiversioning()->is_useless(), "Must be useless, i.e. fast main loop has already disappeared.");
803 // Ignore multiversion_if that just lost its loops. The OpaqueMultiversioning is marked useless,
804 // and will make the multiversion_if constant fold in the next IGVN round.
805 return nullptr;
806 }
807 if (!bol->is_Bool()) {
808 assert(false, "Expected Bool, but got %s", NodeClassNames[bol->Opcode()]);
809 return nullptr;
810 }
811 int cmp_op = bol->in(1)->Opcode();
812 if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
813 return nullptr;
814 }
815 // It is expensive to generate flags from a float compare.
816 // Avoid duplicated float compare.
817 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
818
819 float infrequent_prob = PROB_UNLIKELY_MAG(3);
820 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
821 if (used_inside_loop) {
822 if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
823
824 // BlockLayoutByFrequency optimization moves infrequent branch
825 // from hot path. No point in CMOV'ing in such case (110 is used
826 // instead of 100 to take into account not exactness of float value).
827 if (BlockLayoutByFrequency) {
828 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
829 }
830 }
831 // Check for highly predictable branch. No point in CMOV'ing if
832 // we are going to predict accurately all the time.
833 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
834 //keep going
835 } else if (iff->_prob < infrequent_prob ||
836 iff->_prob > (1.0f - infrequent_prob))
837 return nullptr;
838
839 // --------------
840 // Now replace all Phis with CMOV's
841 Node *cmov_ctrl = iff->in(0);
842 uint flip = (lp->Opcode() == Op_IfTrue);
843 Node_List wq;
844 while (1) {
845 PhiNode* phi = nullptr;
846 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
847 Node *out = region->fast_out(i);
848 if (out->is_Phi()) {
849 phi = out->as_Phi();
850 break;
851 }
852 }
853 if (phi == nullptr || _igvn.type(phi) == Type::TOP || !CMoveNode::supported(_igvn.type(phi))) {
854 break;
855 }
856 // Move speculative ops
857 wq.push(phi);
858 while (wq.size() > 0) {
859 Node *n = wq.pop();
860 for (uint j = 1; j < n->req(); j++) {
861 Node* m = n->in(j);
862 if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
863 set_ctrl(m, cmov_ctrl);
864 wq.push(m);
865 }
866 }
867 }
868 Node* cmov = CMoveNode::make(iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
869 register_new_node(cmov, cmov_ctrl);
870 _igvn.replace_node(phi, cmov);
871 #ifndef PRODUCT
872 if (TraceLoopOpts) {
873 tty->print("CMOV ");
874 r_loop->dump_head();
875 if (Verbose) {
876 bol->in(1)->dump(1);
877 cmov->dump(1);
878 }
879 }
880 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
881 #endif
882 }
883
884 // The useless CFG diamond will fold up later; see the optimization in
885 // RegionNode::Ideal.
886 _igvn._worklist.push(region);
887
888 return iff->in(1);
889 }
890
891 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
892 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
893 Node* u = m->fast_out(i);
894 if (u->is_CFG()) {
895 if (u->is_NeverBranch()) {
896 u = u->as_NeverBranch()->proj_out(0);
897 enqueue_cfg_uses(u, wq);
898 } else {
899 wq.push(u);
900 }
901 }
902 }
903 }
904
905 // Try moving a store out of a loop, right before the loop
906 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
907 // Store has to be first in the loop body
908 IdealLoopTree *n_loop = get_loop(n_ctrl);
909 if (n->is_Store() && n_loop != _ltree_root &&
910 n_loop->is_loop() && n_loop->_head->is_Loop() &&
911 n->in(0) != nullptr) {
912 Node* address = n->in(MemNode::Address);
913 Node* value = n->in(MemNode::ValueIn);
914 Node* mem = n->in(MemNode::Memory);
915 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
916 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
917
918 // - address and value must be loop invariant
919 // - memory must be a memory Phi for the loop
920 // - Store must be the only store on this memory slice in the
921 // loop: if there's another store following this one then value
922 // written at iteration i by the second store could be overwritten
923 // at iteration i+n by the first store: it's not safe to move the
924 // first store out of the loop
925 // - nothing must observe the memory Phi: it guarantees no read
926 // before the store, we are also guaranteed the store post
927 // dominates the loop head (ignoring a possible early
928 // exit). Otherwise there would be extra Phi involved between the
929 // loop's Phi and the store.
930 // - there must be no early exit from the loop before the Store
931 // (such an exit most of the time would be an extra use of the
932 // memory Phi but sometimes is a bottom memory Phi that takes the
933 // store as input).
934
935 if (!n_loop->is_member(address_loop) &&
936 !n_loop->is_member(value_loop) &&
937 mem->is_Phi() && mem->in(0) == n_loop->_head &&
938 mem->outcnt() == 1 &&
939 mem->in(LoopNode::LoopBackControl) == n) {
940
941 assert(n_loop->_tail != nullptr, "need a tail");
942 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
943
944 // Verify that there's no early exit of the loop before the store.
945 bool ctrl_ok = false;
946 {
947 // Follow control from loop head until n, we exit the loop or
948 // we reach the tail
949 ResourceMark rm;
950 Unique_Node_List wq;
951 wq.push(n_loop->_head);
952
953 for (uint next = 0; next < wq.size(); ++next) {
954 Node *m = wq.at(next);
955 if (m == n->in(0)) {
956 ctrl_ok = true;
957 continue;
958 }
959 assert(!has_ctrl(m), "should be CFG");
960 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
961 ctrl_ok = false;
962 break;
963 }
964 enqueue_cfg_uses(m, wq);
965 if (wq.size() > 10) {
966 ctrl_ok = false;
967 break;
968 }
969 }
970 }
971 if (ctrl_ok) {
972 // move the Store
973 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
974 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
975 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
976 // Disconnect the phi now. An empty phi can confuse other
977 // optimizations in this pass of loop opts.
978 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
979 n_loop->_body.yank(mem);
980
981 set_ctrl_and_loop(n, n->in(0));
982
983 return n;
984 }
985 }
986 }
987 return nullptr;
988 }
989
990 // Try moving a store out of a loop, right after the loop
991 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
992 if (n->is_Store() && n->in(0) != nullptr) {
993 Node *n_ctrl = get_ctrl(n);
994 IdealLoopTree *n_loop = get_loop(n_ctrl);
995 // Store must be in a loop
996 if (n_loop != _ltree_root && !n_loop->_irreducible) {
997 Node* address = n->in(MemNode::Address);
998 Node* value = n->in(MemNode::ValueIn);
999 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
1000 // address must be loop invariant
1001 if (!n_loop->is_member(address_loop)) {
1002 // Store must be last on this memory slice in the loop and
1003 // nothing in the loop must observe it
1004 Node* phi = nullptr;
1005 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1006 Node* u = n->fast_out(i);
1007 if (has_ctrl(u)) { // control use?
1008 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1009 if (!n_loop->is_member(u_loop)) {
1010 continue;
1011 }
1012 if (u->is_Phi() && u->in(0) == n_loop->_head) {
1013 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1014 // multiple phis on the same slice are possible
1015 if (phi != nullptr) {
1016 return;
1017 }
1018 phi = u;
1019 continue;
1020 }
1021 }
1022 return;
1023 }
1024 if (phi != nullptr) {
1025 // Nothing in the loop before the store (next iteration)
1026 // must observe the stored value
1027 bool mem_ok = true;
1028 {
1029 ResourceMark rm;
1030 Unique_Node_List wq;
1031 wq.push(phi);
1032 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1033 Node *m = wq.at(next);
1034 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1035 Node* u = m->fast_out(i);
1036 if (u->is_Store() || u->is_Phi()) {
1037 if (u != n) {
1038 wq.push(u);
1039 mem_ok = (wq.size() <= 10);
1040 }
1041 } else {
1042 mem_ok = false;
1043 break;
1044 }
1045 }
1046 }
1047 }
1048 if (mem_ok) {
1049 // Move the store out of the loop if the LCA of all
1050 // users (except for the phi) is outside the loop.
1051 Node* hook = new Node(1);
1052 hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1053 _igvn.rehash_node_delayed(phi);
1054 int count = phi->replace_edge(n, hook, &_igvn);
1055 assert(count > 0, "inconsistent phi");
1056
1057 // Compute latest point this store can go
1058 Node* lca = get_late_ctrl(n, get_ctrl(n));
1059 if (lca->is_OuterStripMinedLoop()) {
1060 lca = lca->in(LoopNode::EntryControl);
1061 }
1062 if (n_loop->is_member(get_loop(lca))) {
1063 // LCA is in the loop - bail out
1064 _igvn.replace_node(hook, n);
1065 return;
1066 }
1067 #ifdef ASSERT
1068 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1069 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1070 n_loop->_head->as_Loop()->verify_strip_mined(1);
1071 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1072 IdealLoopTree* outer_loop = get_loop(outer);
1073 assert(n_loop->_parent == outer_loop, "broken loop tree");
1074 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1075 }
1076 #endif
1077 lca = place_outside_loop(lca, n_loop);
1078 assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1079 assert(get_loop(lca)->_nest < n_loop->_nest || get_loop(lca)->_head->as_Loop()->is_in_infinite_subgraph(), "must not be moved into inner loop");
1080
1081 // Move store out of the loop
1082 _igvn.replace_node(hook, n->in(MemNode::Memory));
1083 _igvn.replace_input_of(n, 0, lca);
1084 set_ctrl_and_loop(n, lca);
1085
1086 // Disconnect the phi now. An empty phi can confuse other
1087 // optimizations in this pass of loop opts..
1088 if (phi->in(LoopNode::LoopBackControl) == phi) {
1089 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1090 n_loop->_body.yank(phi);
1091 }
1092 }
1093 }
1094 }
1095 }
1096 }
1097 }
1098
1099 //------------------------------split_if_with_blocks_pre-----------------------
1100 // Do the real work in a non-recursive function. Data nodes want to be
1101 // cloned in the pre-order so they can feed each other nicely.
1102 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1103 // Cloning these guys is unlikely to win
1104 int n_op = n->Opcode();
1105 if (n_op == Op_MergeMem) {
1106 return n;
1107 }
1108 if (n->is_Proj()) {
1109 return n;
1110 }
1111 // Do not clone-up CmpFXXX variations, as these are always
1112 // followed by a CmpI
1113 if (n->is_Cmp()) {
1114 return n;
1115 }
1116 // Attempt to use a conditional move instead of a phi/branch
1117 if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1118 Node *cmov = conditional_move( n );
1119 if (cmov) {
1120 return cmov;
1121 }
1122 }
1123 if (n->is_CFG() || n->is_LoadStore()) {
1124 return n;
1125 }
1126 if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1127 if (!C->major_progress()) { // If chance of no more loop opts...
1128 _igvn._worklist.push(n); // maybe we'll remove them
1129 }
1130 return n;
1131 }
1132
1133 if (n->is_Con()) {
1134 return n; // No cloning for Con nodes
1135 }
1136
1137 Node *n_ctrl = get_ctrl(n);
1138 if (!n_ctrl) {
1139 return n; // Dead node
1140 }
1141
1142 Node* res = try_move_store_before_loop(n, n_ctrl);
1143 if (res != nullptr) {
1144 return n;
1145 }
1146
1147 // Attempt to remix address expressions for loop invariants
1148 Node *m = remix_address_expressions( n );
1149 if( m ) return m;
1150
1151 if (n_op == Op_AddI) {
1152 Node *nn = convert_add_to_muladd( n );
1153 if ( nn ) return nn;
1154 }
1155
1156 if (n->is_ConstraintCast()) {
1157 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1158 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1159 // Node control inputs don't necessarily agree with loop control info (due to
1160 // transformations happened in between), thus additional dominance check is needed
1161 // to keep loop info valid.
1162 if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1163 _igvn.replace_node(n, dom_cast);
1164 return dom_cast;
1165 }
1166 }
1167
1168 // Determine if the Node has inputs from some local Phi.
1169 // Returns the block to clone thru.
1170 Node *n_blk = has_local_phi_input( n );
1171 if( !n_blk ) return n;
1172
1173 // Do not clone the trip counter through on a CountedLoop
1174 // (messes up the canonical shape).
1175 if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1176 (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1177 return n;
1178 }
1179 // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1180 if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1181 n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1182 return n;
1183 }
1184
1185 // Check for having no control input; not pinned. Allow
1186 // dominating control.
1187 if (n->in(0)) {
1188 Node *dom = idom(n_blk);
1189 if (dom_lca(n->in(0), dom) != n->in(0)) {
1190 return n;
1191 }
1192 }
1193 // Policy: when is it profitable. You must get more wins than
1194 // policy before it is considered profitable. Policy is usually 0,
1195 // so 1 win is considered profitable. Big merges will require big
1196 // cloning, so get a larger policy.
1197 int policy = n_blk->req() >> 2;
1198
1199 // If the loop is a candidate for range check elimination,
1200 // delay splitting through it's phi until a later loop optimization
1201 if (n_blk->is_BaseCountedLoop()) {
1202 IdealLoopTree *lp = get_loop(n_blk);
1203 if (lp && lp->_rce_candidate) {
1204 return n;
1205 }
1206 }
1207
1208 if (must_throttle_split_if()) return n;
1209
1210 // Split 'n' through the merge point if it is profitable
1211 Node *phi = split_thru_phi( n, n_blk, policy );
1212 if (!phi) return n;
1213
1214 // Found a Phi to split thru!
1215 // Replace 'n' with the new phi
1216 _igvn.replace_node( n, phi );
1217 // Moved a load around the loop, 'en-registering' something.
1218 if (n_blk->is_Loop() && n->is_Load() &&
1219 !phi->in(LoopNode::LoopBackControl)->is_Load())
1220 C->set_major_progress();
1221
1222 return phi;
1223 }
1224
1225 static bool merge_point_too_heavy(Compile* C, Node* region) {
1226 // Bail out if the region and its phis have too many users.
1227 int weight = 0;
1228 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1229 weight += region->fast_out(i)->outcnt();
1230 }
1231 int nodes_left = C->max_node_limit() - C->live_nodes();
1232 if (weight * 8 > nodes_left) {
1233 if (PrintOpto) {
1234 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1235 }
1236 return true;
1237 } else {
1238 return false;
1239 }
1240 }
1241
1242 static bool merge_point_safe(Node* region) {
1243 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1244 // having a PhiNode input. This sidesteps the dangerous case where the split
1245 // ConvI2LNode may become TOP if the input Value() does not
1246 // overlap the ConvI2L range, leaving a node which may not dominate its
1247 // uses.
1248 // A better fix for this problem can be found in the BugTraq entry, but
1249 // expediency for Mantis demands this hack.
1250 #ifdef _LP64
1251 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1252 Node* n = region->fast_out(i);
1253 if (n->is_Phi()) {
1254 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1255 Node* m = n->fast_out(j);
1256 if (m->Opcode() == Op_ConvI2L)
1257 return false;
1258 if (m->is_CastII()) {
1259 return false;
1260 }
1261 }
1262 }
1263 }
1264 #endif
1265 return true;
1266 }
1267
1268
1269 //------------------------------place_outside_loop---------------------------------
1270 // Place some computation outside of this loop on the path to the use passed as argument
1271 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1272 Node* head = loop->_head;
1273 assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1274 if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1275 loop = loop->_parent;
1276 assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1277 }
1278
1279 // Pick control right outside the loop
1280 for (;;) {
1281 Node* dom = idom(useblock);
1282 if (loop->is_member(get_loop(dom))) {
1283 break;
1284 }
1285 useblock = dom;
1286 }
1287 assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1288 return useblock;
1289 }
1290
1291
1292 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1293 if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1294 return false;
1295 }
1296 if (!n->in(0)->is_Region()) {
1297 return false;
1298 }
1299
1300 Node* region = n->in(0);
1301 Node* dom = idom(region);
1302 if (!dom->is_If() || !n->as_If()->same_condition(dom, &_igvn)) {
1303 return false;
1304 }
1305 IfNode* dom_if = dom->as_If();
1306 Node* proj_true = dom_if->proj_out(1);
1307 Node* proj_false = dom_if->proj_out(0);
1308
1309 for (uint i = 1; i < region->req(); i++) {
1310 if (is_dominator(proj_true, region->in(i))) {
1311 continue;
1312 }
1313 if (is_dominator(proj_false, region->in(i))) {
1314 continue;
1315 }
1316 return false;
1317 }
1318
1319 return true;
1320 }
1321
1322
1323 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1324 if (must_throttle_split_if()) {
1325 return false;
1326 }
1327
1328 // Do not do 'split-if' if irreducible loops are present.
1329 if (_has_irreducible_loops) {
1330 return false;
1331 }
1332
1333 if (merge_point_too_heavy(C, n_ctrl)) {
1334 return false;
1335 }
1336
1337 // Do not do 'split-if' if some paths are dead. First do dead code
1338 // elimination and then see if its still profitable.
1339 for (uint i = 1; i < n_ctrl->req(); i++) {
1340 if (n_ctrl->in(i) == C->top()) {
1341 return false;
1342 }
1343 }
1344
1345 // If trying to do a 'Split-If' at the loop head, it is only
1346 // profitable if the cmp folds up on BOTH paths. Otherwise we
1347 // risk peeling a loop forever.
1348
1349 // CNC - Disabled for now. Requires careful handling of loop
1350 // body selection for the cloned code. Also, make sure we check
1351 // for any input path not being in the same loop as n_ctrl. For
1352 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1353 // because the alternative loop entry points won't be converted
1354 // into LoopNodes.
1355 IdealLoopTree *n_loop = get_loop(n_ctrl);
1356 for (uint j = 1; j < n_ctrl->req(); j++) {
1357 if (get_loop(n_ctrl->in(j)) != n_loop) {
1358 return false;
1359 }
1360 }
1361
1362 // Check for safety of the merge point.
1363 if (!merge_point_safe(n_ctrl)) {
1364 return false;
1365 }
1366
1367 return true;
1368 }
1369
1370 // Detect if the node is the inner strip-mined loop
1371 // Return: null if it's not the case, or the exit of outer strip-mined loop
1372 static Node* is_inner_of_stripmined_loop(const Node* out) {
1373 Node* out_le = nullptr;
1374
1375 if (out->is_CountedLoopEnd()) {
1376 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1377
1378 if (loop != nullptr && loop->is_strip_mined()) {
1379 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1380 }
1381 }
1382
1383 return out_le;
1384 }
1385
1386 //------------------------------split_if_with_blocks_post----------------------
1387 // Do the real work in a non-recursive function. CFG hackery wants to be
1388 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1389 // info.
1390 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1391
1392 // Cloning Cmp through Phi's involves the split-if transform.
1393 // FastLock is not used by an If
1394 if (n->is_Cmp() && !n->is_FastLock()) {
1395 Node *n_ctrl = get_ctrl(n);
1396 // Determine if the Node has inputs from some local Phi.
1397 // Returns the block to clone thru.
1398 Node *n_blk = has_local_phi_input(n);
1399 if (n_blk != n_ctrl) {
1400 return;
1401 }
1402
1403 if (!can_split_if(n_ctrl)) {
1404 return;
1405 }
1406
1407 if (n->outcnt() != 1) {
1408 return; // Multiple bool's from 1 compare?
1409 }
1410 Node *bol = n->unique_out();
1411 assert(bol->is_Bool(), "expect a bool here");
1412 if (bol->outcnt() != 1) {
1413 return;// Multiple branches from 1 compare?
1414 }
1415 Node *iff = bol->unique_out();
1416
1417 // Check some safety conditions
1418 if (iff->is_If()) { // Classic split-if?
1419 if (iff->in(0) != n_ctrl) {
1420 return; // Compare must be in same blk as if
1421 }
1422 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1423 // Can't split CMove with different control.
1424 if (get_ctrl(iff) != n_ctrl) {
1425 return;
1426 }
1427 if (get_ctrl(iff->in(2)) == n_ctrl ||
1428 get_ctrl(iff->in(3)) == n_ctrl) {
1429 return; // Inputs not yet split-up
1430 }
1431 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1432 return; // Loop-invar test gates loop-varying CMOVE
1433 }
1434 } else {
1435 return; // some other kind of node, such as an Allocate
1436 }
1437
1438 // When is split-if profitable? Every 'win' on means some control flow
1439 // goes dead, so it's almost always a win.
1440 int policy = 0;
1441 // Split compare 'n' through the merge point if it is profitable
1442 Node *phi = split_thru_phi( n, n_ctrl, policy);
1443 if (!phi) {
1444 return;
1445 }
1446
1447 // Found a Phi to split thru!
1448 // Replace 'n' with the new phi
1449 _igvn.replace_node(n, phi);
1450
1451 // Now split the bool up thru the phi
1452 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1453 guarantee(bolphi != nullptr, "null boolean phi node");
1454
1455 _igvn.replace_node(bol, bolphi);
1456 assert(iff->in(1) == bolphi, "");
1457
1458 if (bolphi->Value(&_igvn)->singleton()) {
1459 return;
1460 }
1461
1462 // Conditional-move? Must split up now
1463 if (!iff->is_If()) {
1464 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1465 _igvn.replace_node(iff, cmovphi);
1466 return;
1467 }
1468
1469 // Now split the IF
1470 C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1471 if (TraceLoopOpts) {
1472 tty->print_cr("Split-If");
1473 }
1474 do_split_if(iff);
1475 C->print_method(PHASE_AFTER_SPLIT_IF, 4, iff);
1476 return;
1477 }
1478
1479 // Two identical ifs back to back can be merged
1480 if (try_merge_identical_ifs(n)) {
1481 return;
1482 }
1483
1484 // Check for an IF ready to split; one that has its
1485 // condition codes input coming from a Phi at the block start.
1486 int n_op = n->Opcode();
1487
1488 // Check for an IF being dominated by another IF same test
1489 if (n_op == Op_If ||
1490 n_op == Op_RangeCheck) {
1491 Node *bol = n->in(1);
1492 uint max = bol->outcnt();
1493 // Check for same test used more than once?
1494 if (bol->is_Bool() && (max > 1 || bol->in(1)->is_SubTypeCheck())) {
1495 // Search up IDOMs to see if this IF is dominated.
1496 Node* cmp = bol->in(1);
1497 Node *cutoff = cmp->is_SubTypeCheck() ? dom_lca(get_ctrl(cmp->in(1)), get_ctrl(cmp->in(2))) : get_ctrl(bol);
1498
1499 // Now search up IDOMs till cutoff, looking for a dominating test
1500 Node *prevdom = n;
1501 Node *dom = idom(prevdom);
1502 while (dom != cutoff) {
1503 if (dom->req() > 1 && n->as_If()->same_condition(dom, &_igvn) && prevdom->in(0) == dom &&
1504 safe_for_if_replacement(dom)) {
1505 // It's invalid to move control dependent data nodes in the inner
1506 // strip-mined loop, because:
1507 // 1) break validation of LoopNode::verify_strip_mined()
1508 // 2) move code with side-effect in strip-mined loop
1509 // Move to the exit of outer strip-mined loop in that case.
1510 Node* out_le = is_inner_of_stripmined_loop(dom);
1511 if (out_le != nullptr) {
1512 prevdom = out_le;
1513 }
1514 // Replace the dominated test with an obvious true or false.
1515 // Place it on the IGVN worklist for later cleanup.
1516 C->set_major_progress();
1517 // Split if: pin array accesses that are control dependent on a range check and moved to a regular if,
1518 // to prevent an array load from floating above its range check. There are three cases:
1519 // 1. Move from RangeCheck "a" to RangeCheck "b": don't need to pin. If we ever remove b, then we pin
1520 // all its array accesses at that point.
1521 // 2. We move from RangeCheck "a" to regular if "b": need to pin. If we ever remove b, then its array
1522 // accesses would start to float, since we don't pin at that point.
1523 // 3. If we move from regular if: don't pin. All array accesses are already assumed to be pinned.
1524 bool pin_array_access_nodes = n->Opcode() == Op_RangeCheck &&
1525 prevdom->in(0)->Opcode() != Op_RangeCheck;
1526 dominated_by(prevdom->as_IfProj(), n->as_If(), false, pin_array_access_nodes);
1527 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1528 return;
1529 }
1530 prevdom = dom;
1531 dom = idom(prevdom);
1532 }
1533 }
1534 }
1535
1536 try_sink_out_of_loop(n);
1537 if (C->failing()) {
1538 return;
1539 }
1540
1541 try_move_store_after_loop(n);
1542 }
1543
1544 // Transform:
1545 //
1546 // if (some_condition) {
1547 // // body 1
1548 // } else {
1549 // // body 2
1550 // }
1551 // if (some_condition) {
1552 // // body 3
1553 // } else {
1554 // // body 4
1555 // }
1556 //
1557 // into:
1558 //
1559 //
1560 // if (some_condition) {
1561 // // body 1
1562 // // body 3
1563 // } else {
1564 // // body 2
1565 // // body 4
1566 // }
1567 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1568 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1569 Node *n_ctrl = n->in(0);
1570 IfNode* dom_if = idom(n_ctrl)->as_If();
1571 if (n->in(1) != dom_if->in(1)) {
1572 assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1573 (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1574 dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1575 _igvn.replace_input_of(n, 1, dom_if->in(1));
1576 }
1577 ProjNode* dom_proj_true = dom_if->proj_out(1);
1578 ProjNode* dom_proj_false = dom_if->proj_out(0);
1579
1580 // Now split the IF
1581 RegionNode* new_false_region;
1582 RegionNode* new_true_region;
1583 do_split_if(n, &new_false_region, &new_true_region);
1584 assert(new_false_region->req() == new_true_region->req(), "");
1585 #ifdef ASSERT
1586 for (uint i = 1; i < new_false_region->req(); ++i) {
1587 assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1588 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");
1589 }
1590 #endif
1591 assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1592
1593 // We now have:
1594 // if (some_condition) {
1595 // // body 1
1596 // if (some_condition) {
1597 // body3: // new_true_region
1598 // // body3
1599 // } else {
1600 // goto body4;
1601 // }
1602 // } else {
1603 // // body 2
1604 // if (some_condition) {
1605 // goto body3;
1606 // } else {
1607 // body4: // new_false_region
1608 // // body4;
1609 // }
1610 // }
1611 //
1612
1613 // clone pinned nodes thru the resulting regions
1614 push_pinned_nodes_thru_region(dom_if, new_true_region);
1615 push_pinned_nodes_thru_region(dom_if, new_false_region);
1616
1617 // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1618 // 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
1619 // unrelated control dependency.
1620 for (uint i = 1; i < new_false_region->req(); i++) {
1621 if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1622 dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1623 } else {
1624 assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1625 dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1626 }
1627 }
1628 return true;
1629 }
1630 return false;
1631 }
1632
1633 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1634 for (DUIterator i = region->outs(); region->has_out(i); i++) {
1635 Node* u = region->out(i);
1636 if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1637 continue;
1638 }
1639 assert(u->in(0) == region, "not a control dependent node?");
1640 uint j = 1;
1641 for (; j < u->req(); ++j) {
1642 Node* in = u->in(j);
1643 if (!is_dominator(ctrl_or_self(in), dom_if)) {
1644 break;
1645 }
1646 }
1647 if (j == u->req()) {
1648 Node *phi = PhiNode::make_blank(region, u);
1649 for (uint k = 1; k < region->req(); ++k) {
1650 Node* clone = u->clone();
1651 clone->set_req(0, region->in(k));
1652 register_new_node(clone, region->in(k));
1653 phi->init_req(k, clone);
1654 }
1655 register_new_node(phi, region);
1656 _igvn.replace_node(u, phi);
1657 --i;
1658 }
1659 }
1660 }
1661
1662 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1663 if (!dom->is_CountedLoopEnd()) {
1664 return true;
1665 }
1666 CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1667 CountedLoopNode* cl = le->loopnode();
1668 if (cl == nullptr) {
1669 return true;
1670 }
1671 if (!cl->is_main_loop()) {
1672 return true;
1673 }
1674 if (cl->is_canonical_loop_entry() == nullptr) {
1675 return true;
1676 }
1677 // Further unrolling is possible so loop exit condition might change
1678 return false;
1679 }
1680
1681 // See if a shared loop-varying computation has no loop-varying uses.
1682 // Happens if something is only used for JVM state in uncommon trap exits,
1683 // like various versions of induction variable+offset. Clone the
1684 // computation per usage to allow it to sink out of the loop.
1685 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1686 bool is_raw_to_oop_cast = n->is_ConstraintCast() &&
1687 n->in(1)->bottom_type()->isa_rawptr() &&
1688 !n->bottom_type()->isa_rawptr();
1689
1690 if (has_ctrl(n) &&
1691 !n->is_Phi() &&
1692 !n->is_Bool() &&
1693 !n->is_Proj() &&
1694 !n->is_MergeMem() &&
1695 !n->is_CMove() &&
1696 !n->is_OpaqueNotNull() &&
1697 !n->is_OpaqueInitializedAssertionPredicate() &&
1698 !n->is_OpaqueTemplateAssertionPredicate() &&
1699 !is_raw_to_oop_cast && // don't extend live ranges of raw oops
1700 (KillPathsReachableByDeadTypeNode || !n->is_Type())
1701 ) {
1702 Node *n_ctrl = get_ctrl(n);
1703 IdealLoopTree *n_loop = get_loop(n_ctrl);
1704
1705 if (n->in(0) != nullptr) {
1706 IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1707 if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1708 // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1709 // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1710 // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1711 Node* maybe_pinned_n = n;
1712 Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1713 if (n->depends_only_on_test()) {
1714 Node* pinned_clone = n->pin_array_access_node();
1715 if (pinned_clone != nullptr) {
1716 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1717 // range check for that access. If that condition is replaced by an identical dominating one, then an
1718 // unpinned load would risk floating above its range check.
1719 register_new_node(pinned_clone, n_ctrl);
1720 maybe_pinned_n = pinned_clone;
1721 _igvn.replace_node(n, pinned_clone);
1722 }
1723 }
1724 _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1725 }
1726 }
1727 if (n_loop != _ltree_root && n->outcnt() > 1) {
1728 // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1729 // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1730 Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1731 if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1732 ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1733 if (n->is_Store() || n->is_LoadStore()) {
1734 assert(false, "no node with a side effect");
1735 C->record_failure("no node with a side effect");
1736 return;
1737 }
1738 Node* outer_loop_clone = nullptr;
1739 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1740 Node* u = n->last_out(j); // Clone private computation per use
1741 _igvn.rehash_node_delayed(u);
1742 Node* x = nullptr;
1743 if (n->depends_only_on_test()) {
1744 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1745 // range check for that access. If that condition is replaced by an identical dominating one, then an
1746 // unpinned load would risk floating above its range check.
1747 x = n->pin_array_access_node();
1748 }
1749 if (x == nullptr) {
1750 x = n->clone();
1751 }
1752 Node* x_ctrl = nullptr;
1753 if (u->is_Phi()) {
1754 // Replace all uses of normal nodes. Replace Phi uses
1755 // individually, so the separate Nodes can sink down
1756 // different paths.
1757 uint k = 1;
1758 while (u->in(k) != n) k++;
1759 u->set_req(k, x);
1760 // x goes next to Phi input path
1761 x_ctrl = u->in(0)->in(k);
1762 // Find control for 'x' next to use but not inside inner loops.
1763 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1764 --j;
1765 } else { // Normal use
1766 if (has_ctrl(u)) {
1767 x_ctrl = get_ctrl(u);
1768 } else {
1769 x_ctrl = u->in(0);
1770 }
1771 // Find control for 'x' next to use but not inside inner loops.
1772 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1773 // Replace all uses
1774 if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1775 // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1776 // anymore now that we're going to pin n as well
1777 _igvn.replace_node(u, x);
1778 --j;
1779 } else {
1780 int nb = u->replace_edge(n, x, &_igvn);
1781 j -= nb;
1782 }
1783 }
1784
1785 if (n->is_Load()) {
1786 // For loads, add a control edge to a CFG node outside of the loop
1787 // to force them to not combine and return back inside the loop
1788 // during GVN optimization (4641526).
1789 assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1790
1791 IdealLoopTree* x_loop = get_loop(x_ctrl);
1792 Node* x_head = x_loop->_head;
1793 if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1794 // Do not add duplicate LoadNodes to the outer strip mined loop
1795 if (outer_loop_clone != nullptr) {
1796 _igvn.replace_node(x, outer_loop_clone);
1797 continue;
1798 }
1799 outer_loop_clone = x;
1800 }
1801 x->set_req(0, x_ctrl);
1802 } else if (n->in(0) != nullptr){
1803 x->set_req(0, x_ctrl);
1804 }
1805 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1806 assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1807 register_new_node(x, x_ctrl);
1808
1809 // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
1810 // All AddP nodes must keep the same base after sinking so:
1811 // 1- We don't add a CastPP here until the last one of the chain is sunk: if part of the chain is not sunk,
1812 // their bases remain the same.
1813 // (see 2- below)
1814 assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1815 x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1816 !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1817 if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
1818 !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1819 assert(!x->is_Load(), "load should be pinned");
1820 // Use a cast node to pin clone out of loop
1821 Node* cast = nullptr;
1822 for (uint k = 0; k < x->req(); k++) {
1823 Node* in = x->in(k);
1824 if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
1825 const Type* in_t = _igvn.type(in);
1826 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
1827 ConstraintCastNode::UnconditionalDependency, nullptr);
1828 }
1829 if (cast != nullptr) {
1830 Node* prev = _igvn.hash_find_insert(cast);
1831 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
1832 cast->destruct(&_igvn);
1833 cast = prev;
1834 } else {
1835 register_new_node(cast, x_ctrl);
1836 }
1837 x->replace_edge(in, cast);
1838 // Chain of AddP nodes:
1839 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
1840 if (x->is_AddP() && k == AddPNode::Base) {
1841 update_addp_chain_base(x, n->in(AddPNode::Base), cast);
1842 }
1843 break;
1844 }
1845 }
1846 assert(cast != nullptr, "must have added a cast to pin the node");
1847 }
1848 }
1849 _igvn.remove_dead_node(n);
1850 }
1851 _dom_lca_tags_round = 0;
1852 }
1853 }
1854 }
1855
1856 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
1857 ResourceMark rm;
1858 Node_List wq;
1859 wq.push(x);
1860 while (wq.size() != 0) {
1861 Node* n = wq.pop();
1862 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1863 Node* u = n->fast_out(i);
1864 if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
1865 _igvn.replace_input_of(u, AddPNode::Base, new_base);
1866 wq.push(u);
1867 }
1868 }
1869 }
1870 }
1871
1872 // Compute the early control of a node by following its inputs until we reach
1873 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
1874 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
1875 Node* early_ctrl = nullptr;
1876 ResourceMark rm;
1877 Unique_Node_List wq;
1878 wq.push(n);
1879 for (uint i = 0; i < wq.size(); i++) {
1880 Node* m = wq.at(i);
1881 Node* c = nullptr;
1882 if (m->is_CFG()) {
1883 c = m;
1884 } else if (m->pinned()) {
1885 c = m->in(0);
1886 } else {
1887 for (uint j = 0; j < m->req(); j++) {
1888 Node* in = m->in(j);
1889 if (in != nullptr) {
1890 wq.push(in);
1891 }
1892 }
1893 }
1894 if (c != nullptr) {
1895 assert(is_dominator(c, n_ctrl), "control input must dominate current control");
1896 if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
1897 early_ctrl = c;
1898 }
1899 }
1900 }
1901 assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
1902 return early_ctrl;
1903 }
1904
1905 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
1906 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1907 Node* u = n->fast_out(i);
1908 if (u->is_Opaque1()) {
1909 return false; // Found loop limit, bugfix for 4677003
1910 }
1911 // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
1912 // get_late_ctrl_with_anti_dep() use their own tag
1913 _dom_lca_tags_round++;
1914 assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
1915
1916 if (u->is_Phi()) {
1917 for (uint j = 1; j < u->req(); ++j) {
1918 if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
1919 return false;
1920 }
1921 }
1922 } else {
1923 Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
1924 if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
1925 return false;
1926 }
1927 }
1928 }
1929 return true;
1930 }
1931
1932 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
1933 if (n->is_Load()) {
1934 ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
1935 }
1936 IdealLoopTree *u_loop = get_loop(ctrl);
1937 if (u_loop == n_loop) {
1938 return false; // Found loop-varying use
1939 }
1940 if (n_loop->is_member(u_loop)) {
1941 return false; // Found use in inner loop
1942 }
1943 // Sinking a node from a pre loop to its main loop pins the node between the pre and main loops. If that node is input
1944 // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
1945 // test of the pre loop above the point in the graph where it's pinned.
1946 if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
1947 CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
1948 if (is_dominator(pre_loop->loopexit(), ctrl)) {
1949 return false;
1950 }
1951 }
1952 return true;
1953 }
1954
1955 //------------------------------split_if_with_blocks---------------------------
1956 // Check for aggressive application of 'split-if' optimization,
1957 // using basic block level info.
1958 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1959 Node* root = C->root();
1960 visited.set(root->_idx); // first, mark root as visited
1961 // Do pre-visit work for root
1962 Node* n = split_if_with_blocks_pre(root);
1963 uint cnt = n->outcnt();
1964 uint i = 0;
1965
1966 while (true) {
1967 // Visit all children
1968 if (i < cnt) {
1969 Node* use = n->raw_out(i);
1970 ++i;
1971 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1972 // Now do pre-visit work for this use
1973 use = split_if_with_blocks_pre(use);
1974 nstack.push(n, i); // Save parent and next use's index.
1975 n = use; // Process all children of current use.
1976 cnt = use->outcnt();
1977 i = 0;
1978 }
1979 }
1980 else {
1981 // All of n's children have been processed, complete post-processing.
1982 if (cnt != 0 && !n->is_Con()) {
1983 assert(has_node(n), "no dead nodes");
1984 split_if_with_blocks_post(n);
1985 if (C->failing()) {
1986 return;
1987 }
1988 }
1989 if (must_throttle_split_if()) {
1990 nstack.clear();
1991 }
1992 if (nstack.is_empty()) {
1993 // Finished all nodes on stack.
1994 break;
1995 }
1996 // Get saved parent node and next use's index. Visit the rest of uses.
1997 n = nstack.node();
1998 cnt = n->outcnt();
1999 i = nstack.index();
2000 nstack.pop();
2001 }
2002 }
2003 }
2004
2005
2006 //=============================================================================
2007 //
2008 // C L O N E A L O O P B O D Y
2009 //
2010
2011 //------------------------------clone_iff--------------------------------------
2012 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2013 // "Nearly" because all Nodes have been cloned from the original in the loop,
2014 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2015 // through the Phi recursively, and return a Bool.
2016 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2017
2018 // Convert this Phi into a Phi merging Bools
2019 uint i;
2020 for (i = 1; i < phi->req(); i++) {
2021 Node* b = phi->in(i);
2022 if (b->is_Phi()) {
2023 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2024 } else {
2025 assert(b->is_Bool() || b->is_OpaqueNotNull() || b->is_OpaqueInitializedAssertionPredicate(),
2026 "bool, non-null check with OpaqueNotNull or Initialized Assertion Predicate with its Opaque node");
2027 }
2028 }
2029 Node* n = phi->in(1);
2030 Node* sample_opaque = nullptr;
2031 Node *sample_bool = nullptr;
2032 if (n->is_OpaqueNotNull() || n->is_OpaqueInitializedAssertionPredicate()) {
2033 sample_opaque = n;
2034 sample_bool = n->in(1);
2035 assert(sample_bool->is_Bool(), "wrong type");
2036 } else {
2037 sample_bool = n;
2038 }
2039 Node *sample_cmp = sample_bool->in(1);
2040
2041 // Make Phis to merge the Cmp's inputs.
2042 PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
2043 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2044 for (i = 1; i < phi->req(); i++) {
2045 Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2046 Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2047 phi1->set_req(i, n1);
2048 phi2->set_req(i, n2);
2049 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2050 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2051 }
2052 // See if these Phis have been made before.
2053 // Register with optimizer
2054 Node *hit1 = _igvn.hash_find_insert(phi1);
2055 if (hit1) { // Hit, toss just made Phi
2056 _igvn.remove_dead_node(phi1); // Remove new phi
2057 assert(hit1->is_Phi(), "" );
2058 phi1 = (PhiNode*)hit1; // Use existing phi
2059 } else { // Miss
2060 _igvn.register_new_node_with_optimizer(phi1);
2061 }
2062 Node *hit2 = _igvn.hash_find_insert(phi2);
2063 if (hit2) { // Hit, toss just made Phi
2064 _igvn.remove_dead_node(phi2); // Remove new phi
2065 assert(hit2->is_Phi(), "" );
2066 phi2 = (PhiNode*)hit2; // Use existing phi
2067 } else { // Miss
2068 _igvn.register_new_node_with_optimizer(phi2);
2069 }
2070 // Register Phis with loop/block info
2071 set_ctrl(phi1, phi->in(0));
2072 set_ctrl(phi2, phi->in(0));
2073 // Make a new Cmp
2074 Node *cmp = sample_cmp->clone();
2075 cmp->set_req(1, phi1);
2076 cmp->set_req(2, phi2);
2077 _igvn.register_new_node_with_optimizer(cmp);
2078 set_ctrl(cmp, phi->in(0));
2079
2080 // Make a new Bool
2081 Node *b = sample_bool->clone();
2082 b->set_req(1,cmp);
2083 _igvn.register_new_node_with_optimizer(b);
2084 set_ctrl(b, phi->in(0));
2085
2086 if (sample_opaque != nullptr) {
2087 Node* opaque = sample_opaque->clone();
2088 opaque->set_req(1, b);
2089 _igvn.register_new_node_with_optimizer(opaque);
2090 set_ctrl(opaque, phi->in(0));
2091 return opaque;
2092 }
2093
2094 assert(b->is_Bool(), "");
2095 return b;
2096 }
2097
2098 //------------------------------clone_bool-------------------------------------
2099 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2100 // "Nearly" because all Nodes have been cloned from the original in the loop,
2101 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2102 // through the Phi recursively, and return a Bool.
2103 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2104 uint i;
2105 // Convert this Phi into a Phi merging Bools
2106 for( i = 1; i < phi->req(); i++ ) {
2107 Node *b = phi->in(i);
2108 if( b->is_Phi() ) {
2109 _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2110 } else {
2111 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2112 }
2113 }
2114
2115 Node *sample_cmp = phi->in(1);
2116
2117 // Make Phis to merge the Cmp's inputs.
2118 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2119 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2120 for( uint j = 1; j < phi->req(); j++ ) {
2121 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2122 Node *n1, *n2;
2123 if( cmp_top->is_Cmp() ) {
2124 n1 = cmp_top->in(1);
2125 n2 = cmp_top->in(2);
2126 } else {
2127 n1 = n2 = cmp_top;
2128 }
2129 phi1->set_req( j, n1 );
2130 phi2->set_req( j, n2 );
2131 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2132 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2133 }
2134
2135 // See if these Phis have been made before.
2136 // Register with optimizer
2137 Node *hit1 = _igvn.hash_find_insert(phi1);
2138 if( hit1 ) { // Hit, toss just made Phi
2139 _igvn.remove_dead_node(phi1); // Remove new phi
2140 assert( hit1->is_Phi(), "" );
2141 phi1 = (PhiNode*)hit1; // Use existing phi
2142 } else { // Miss
2143 _igvn.register_new_node_with_optimizer(phi1);
2144 }
2145 Node *hit2 = _igvn.hash_find_insert(phi2);
2146 if( hit2 ) { // Hit, toss just made Phi
2147 _igvn.remove_dead_node(phi2); // Remove new phi
2148 assert( hit2->is_Phi(), "" );
2149 phi2 = (PhiNode*)hit2; // Use existing phi
2150 } else { // Miss
2151 _igvn.register_new_node_with_optimizer(phi2);
2152 }
2153 // Register Phis with loop/block info
2154 set_ctrl(phi1, phi->in(0));
2155 set_ctrl(phi2, phi->in(0));
2156 // Make a new Cmp
2157 Node *cmp = sample_cmp->clone();
2158 cmp->set_req( 1, phi1 );
2159 cmp->set_req( 2, phi2 );
2160 _igvn.register_new_node_with_optimizer(cmp);
2161 set_ctrl(cmp, phi->in(0));
2162
2163 assert( cmp->is_Cmp(), "" );
2164 return (CmpNode*)cmp;
2165 }
2166
2167 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2168 IdealLoopTree* loop, IdealLoopTree* outer_loop,
2169 Node_List*& split_if_set, Node_List*& split_bool_set,
2170 Node_List*& split_cex_set, Node_List& worklist,
2171 uint new_counter, CloneLoopMode mode) {
2172 Node* nnn = old_new[old->_idx];
2173 // Copy uses to a worklist, so I can munge the def-use info
2174 // with impunity.
2175 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2176 worklist.push(old->fast_out(j));
2177
2178 while( worklist.size() ) {
2179 Node *use = worklist.pop();
2180 if (!has_node(use)) continue; // Ignore dead nodes
2181 if (use->in(0) == C->top()) continue;
2182 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2183 // Check for data-use outside of loop - at least one of OLD or USE
2184 // must not be a CFG node.
2185 #ifdef ASSERT
2186 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2187 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2188 assert(mode != IgnoreStripMined, "incorrect cloning mode");
2189 assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2190 }
2191 #endif
2192 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2193
2194 // If the Data use is an IF, that means we have an IF outside the
2195 // loop that is switching on a condition that is set inside the
2196 // loop. Happens if people set a loop-exit flag; then test the flag
2197 // in the loop to break the loop, then test is again outside the
2198 // loop to determine which way the loop exited.
2199 //
2200 // For several uses we need to make sure that there is no phi between,
2201 // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2202 // to avoid such a phi in between.
2203 // For example, it is unexpected that there is a Phi between an
2204 // AllocateArray node and its ValidLengthTest input that could cause
2205 // split if to break.
2206 assert(!use->is_OpaqueTemplateAssertionPredicate(),
2207 "should not clone a Template Assertion Predicate which should be removed once it's useless");
2208 if (use->is_If() || use->is_CMove() || use->is_OpaqueNotNull() || use->is_OpaqueInitializedAssertionPredicate() ||
2209 (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2210 // Since this code is highly unlikely, we lazily build the worklist
2211 // of such Nodes to go split.
2212 if (!split_if_set) {
2213 split_if_set = new Node_List();
2214 }
2215 split_if_set->push(use);
2216 }
2217 if (use->is_Bool()) {
2218 if (!split_bool_set) {
2219 split_bool_set = new Node_List();
2220 }
2221 split_bool_set->push(use);
2222 }
2223 if (use->Opcode() == Op_CreateEx) {
2224 if (!split_cex_set) {
2225 split_cex_set = new Node_List();
2226 }
2227 split_cex_set->push(use);
2228 }
2229
2230
2231 // Get "block" use is in
2232 uint idx = 0;
2233 while( use->in(idx) != old ) idx++;
2234 Node *prev = use->is_CFG() ? use : get_ctrl(use);
2235 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2236 Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2237 ? prev->in(2)
2238 : idom(prev);
2239 if( use->is_Phi() ) // Phi use is in prior block
2240 cfg = prev->in(idx); // NOT in block of Phi itself
2241 if (cfg->is_top()) { // Use is dead?
2242 _igvn.replace_input_of(use, idx, C->top());
2243 continue;
2244 }
2245
2246 // If use is referenced through control edge... (idx == 0)
2247 if (mode == IgnoreStripMined && idx == 0) {
2248 LoopNode *head = loop->_head->as_Loop();
2249 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2250 // That node is outside the inner loop, leave it outside the
2251 // outer loop as well to not confuse verification code.
2252 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2253 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2254 continue;
2255 }
2256 }
2257
2258 while(!outer_loop->is_member(get_loop(cfg))) {
2259 prev = cfg;
2260 cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2261 }
2262 // If the use occurs after merging several exits from the loop, then
2263 // old value must have dominated all those exits. Since the same old
2264 // value was used on all those exits we did not need a Phi at this
2265 // merge point. NOW we do need a Phi here. Each loop exit value
2266 // is now merged with the peeled body exit; each exit gets its own
2267 // private Phi and those Phis need to be merged here.
2268 Node *phi;
2269 if( prev->is_Region() ) {
2270 if( idx == 0 ) { // Updating control edge?
2271 phi = prev; // Just use existing control
2272 } else { // Else need a new Phi
2273 phi = PhiNode::make( prev, old );
2274 // Now recursively fix up the new uses of old!
2275 for( uint i = 1; i < prev->req(); i++ ) {
2276 worklist.push(phi); // Onto worklist once for each 'old' input
2277 }
2278 }
2279 } else {
2280 // Get new RegionNode merging old and new loop exits
2281 prev = old_new[prev->_idx];
2282 assert( prev, "just made this in step 7" );
2283 if( idx == 0) { // Updating control edge?
2284 phi = prev; // Just use existing control
2285 } else { // Else need a new Phi
2286 // Make a new Phi merging data values properly
2287 phi = PhiNode::make( prev, old );
2288 phi->set_req( 1, nnn );
2289 }
2290 }
2291 // If inserting a new Phi, check for prior hits
2292 if( idx != 0 ) {
2293 Node *hit = _igvn.hash_find_insert(phi);
2294 if( hit == nullptr ) {
2295 _igvn.register_new_node_with_optimizer(phi); // Register new phi
2296 } else { // or
2297 // Remove the new phi from the graph and use the hit
2298 _igvn.remove_dead_node(phi);
2299 phi = hit; // Use existing phi
2300 }
2301 set_ctrl(phi, prev);
2302 }
2303 // Make 'use' use the Phi instead of the old loop body exit value
2304 assert(use->in(idx) == old, "old is still input of use");
2305 // We notify all uses of old, including use, and the indirect uses,
2306 // that may now be optimized because we have replaced old with phi.
2307 _igvn.add_users_to_worklist(old);
2308 if (idx == 0 &&
2309 use->depends_only_on_test()) {
2310 Node* pinned_clone = use->pin_array_access_node();
2311 if (pinned_clone != nullptr) {
2312 // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path
2313 // into the region is left, an array load could become dependent on a condition that's not a range check for
2314 // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
2315 // floating above its range check.
2316 pinned_clone->set_req(0, phi);
2317 register_new_node_with_ctrl_of(pinned_clone, use);
2318 _igvn.replace_node(use, pinned_clone);
2319 continue;
2320 }
2321 }
2322 _igvn.replace_input_of(use, idx, phi);
2323 if( use->_idx >= new_counter ) { // If updating new phis
2324 // Not needed for correctness, but prevents a weak assert
2325 // in AddPNode from tripping (when we end up with different
2326 // base & derived Phis that will become the same after
2327 // IGVN does CSE).
2328 Node *hit = _igvn.hash_find_insert(use);
2329 if( hit ) // Go ahead and re-hash for hits.
2330 _igvn.replace_node( use, hit );
2331 }
2332 }
2333 }
2334 }
2335
2336 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2337 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2338 bool check_old_new) {
2339 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2340 Node* u = n->fast_out(j);
2341 assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2342 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2343 Node* c = phase->get_ctrl(u);
2344 IdealLoopTree* u_loop = phase->get_loop(c);
2345 assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2346 if (!loop->is_member(u_loop)) {
2347 if (outer_loop->is_member(u_loop)) {
2348 wq.push(u);
2349 } else {
2350 // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2351 // the outer loop too
2352 Node* u_c = u->in(0);
2353 if (u_c != nullptr) {
2354 IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2355 if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2356 wq.push(u);
2357 }
2358 }
2359 }
2360 }
2361 }
2362 }
2363 }
2364
2365 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2366 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2367 Node_List& extra_data_nodes) {
2368 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2369 CountedLoopNode* cl = head->as_CountedLoop();
2370 Node* l = cl->outer_loop();
2371 Node* tail = cl->outer_loop_tail();
2372 IfNode* le = cl->outer_loop_end();
2373 Node* sfpt = cl->outer_safepoint();
2374 CountedLoopEndNode* cle = cl->loopexit();
2375 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2376 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2377 Node* cle_out = cle->proj_out(false);
2378
2379 Node* new_sfpt = nullptr;
2380 Node* new_cle_out = cle_out->clone();
2381 old_new.map(cle_out->_idx, new_cle_out);
2382 if (mode == CloneIncludesStripMined) {
2383 // clone outer loop body
2384 Node* new_l = l->clone();
2385 Node* new_tail = tail->clone();
2386 IfNode* new_le = le->clone()->as_If();
2387 new_sfpt = sfpt->clone();
2388
2389 set_loop(new_l, outer_loop->_parent);
2390 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2391 set_loop(new_cle_out, outer_loop->_parent);
2392 set_idom(new_cle_out, new_cle, dd);
2393 set_loop(new_sfpt, outer_loop->_parent);
2394 set_idom(new_sfpt, new_cle_out, dd);
2395 set_loop(new_le, outer_loop->_parent);
2396 set_idom(new_le, new_sfpt, dd);
2397 set_loop(new_tail, outer_loop->_parent);
2398 set_idom(new_tail, new_le, dd);
2399 set_idom(new_cl, new_l, dd);
2400
2401 old_new.map(l->_idx, new_l);
2402 old_new.map(tail->_idx, new_tail);
2403 old_new.map(le->_idx, new_le);
2404 old_new.map(sfpt->_idx, new_sfpt);
2405
2406 new_l->set_req(LoopNode::LoopBackControl, new_tail);
2407 new_l->set_req(0, new_l);
2408 new_tail->set_req(0, new_le);
2409 new_le->set_req(0, new_sfpt);
2410 new_sfpt->set_req(0, new_cle_out);
2411 new_cle_out->set_req(0, new_cle);
2412 new_cl->set_req(LoopNode::EntryControl, new_l);
2413
2414 _igvn.register_new_node_with_optimizer(new_l);
2415 _igvn.register_new_node_with_optimizer(new_tail);
2416 _igvn.register_new_node_with_optimizer(new_le);
2417 } else {
2418 Node *newhead = old_new[loop->_head->_idx];
2419 newhead->as_Loop()->clear_strip_mined();
2420 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2421 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2422 }
2423 // Look at data node that were assigned a control in the outer
2424 // loop: they are kept in the outer loop by the safepoint so start
2425 // from the safepoint node's inputs.
2426 IdealLoopTree* outer_loop = get_loop(l);
2427 Node_Stack stack(2);
2428 stack.push(sfpt, 1);
2429 uint new_counter = C->unique();
2430 while (stack.size() > 0) {
2431 Node* n = stack.node();
2432 uint i = stack.index();
2433 while (i < n->req() &&
2434 (n->in(i) == nullptr ||
2435 !has_ctrl(n->in(i)) ||
2436 get_loop(get_ctrl(n->in(i))) != outer_loop ||
2437 (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2438 i++;
2439 }
2440 if (i < n->req()) {
2441 stack.set_index(i+1);
2442 stack.push(n->in(i), 0);
2443 } else {
2444 assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2445 Node* m = n == sfpt ? new_sfpt : n->clone();
2446 if (m != nullptr) {
2447 for (uint i = 0; i < n->req(); i++) {
2448 if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2449 m->set_req(i, old_new[m->in(i)->_idx]);
2450 }
2451 }
2452 } else {
2453 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2454 }
2455 if (n != sfpt) {
2456 extra_data_nodes.push(n);
2457 _igvn.register_new_node_with_optimizer(m);
2458 assert(get_ctrl(n) == cle_out, "what other control?");
2459 set_ctrl(m, new_cle_out);
2460 old_new.map(n->_idx, m);
2461 }
2462 stack.pop();
2463 }
2464 }
2465 if (mode == CloneIncludesStripMined) {
2466 _igvn.register_new_node_with_optimizer(new_sfpt);
2467 _igvn.register_new_node_with_optimizer(new_cle_out);
2468 }
2469 // Some other transformation may have pessimistically assigned some
2470 // data nodes to the outer loop. Set their control so they are out
2471 // of the outer loop.
2472 ResourceMark rm;
2473 Unique_Node_List wq;
2474 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2475 Node* old = extra_data_nodes.at(i);
2476 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2477 }
2478
2479 for (uint i = 0; i < loop->_body.size(); i++) {
2480 Node* old = loop->_body.at(i);
2481 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2482 }
2483
2484 Node* inner_out = sfpt->in(0);
2485 if (inner_out->outcnt() > 1) {
2486 collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2487 }
2488
2489 Node* new_ctrl = cl->outer_loop_exit();
2490 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2491 for (uint i = 0; i < wq.size(); i++) {
2492 Node* n = wq.at(i);
2493 set_ctrl(n, new_ctrl);
2494 if (n->in(0) != nullptr) {
2495 _igvn.replace_input_of(n, 0, new_ctrl);
2496 }
2497 collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2498 }
2499 } else {
2500 Node *newhead = old_new[loop->_head->_idx];
2501 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2502 }
2503 }
2504
2505 //------------------------------clone_loop-------------------------------------
2506 //
2507 // C L O N E A L O O P B O D Y
2508 //
2509 // This is the basic building block of the loop optimizations. It clones an
2510 // entire loop body. It makes an old_new loop body mapping; with this mapping
2511 // you can find the new-loop equivalent to an old-loop node. All new-loop
2512 // nodes are exactly equal to their old-loop counterparts, all edges are the
2513 // same. All exits from the old-loop now have a RegionNode that merges the
2514 // equivalent new-loop path. This is true even for the normal "loop-exit"
2515 // condition. All uses of loop-invariant old-loop values now come from (one
2516 // or more) Phis that merge their new-loop equivalents.
2517 //
2518 // This operation leaves the graph in an illegal state: there are two valid
2519 // control edges coming from the loop pre-header to both loop bodies. I'll
2520 // definitely have to hack the graph after running this transform.
2521 //
2522 // From this building block I will further edit edges to perform loop peeling
2523 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2524 //
2525 // Parameter side_by_size_idom:
2526 // When side_by_size_idom is null, the dominator tree is constructed for
2527 // the clone loop to dominate the original. Used in construction of
2528 // pre-main-post loop sequence.
2529 // When nonnull, the clone and original are side-by-side, both are
2530 // dominated by the side_by_side_idom node. Used in construction of
2531 // unswitched loops.
2532 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2533 CloneLoopMode mode, Node* side_by_side_idom) {
2534
2535 LoopNode* head = loop->_head->as_Loop();
2536 head->verify_strip_mined(1);
2537
2538 if (C->do_vector_loop() && PrintOpto) {
2539 const char* mname = C->method()->name()->as_quoted_ascii();
2540 if (mname != nullptr) {
2541 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2542 }
2543 }
2544
2545 CloneMap& cm = C->clone_map();
2546 if (C->do_vector_loop()) {
2547 cm.set_clone_idx(cm.max_gen()+1);
2548 #ifndef PRODUCT
2549 if (PrintOpto) {
2550 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2551 loop->dump_head();
2552 }
2553 #endif
2554 }
2555
2556 // Step 1: Clone the loop body. Make the old->new mapping.
2557 clone_loop_body(loop->_body, old_new, &cm);
2558
2559 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2560
2561 // Step 2: Fix the edges in the new body. If the old input is outside the
2562 // loop use it. If the old input is INside the loop, use the corresponding
2563 // new node instead.
2564 fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2565
2566 Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2567 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2568
2569 // Step 3: Now fix control uses. Loop varying control uses have already
2570 // been fixed up (as part of all input edges in Step 2). Loop invariant
2571 // control uses must be either an IfFalse or an IfTrue. Make a merge
2572 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2573 // refer to this.
2574 Node_List worklist;
2575 uint new_counter = C->unique();
2576 fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2577
2578 // Step 4: If loop-invariant use is not control, it must be dominated by a
2579 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2580 // there if needed. Make a Phi there merging old and new used values.
2581 Node_List *split_if_set = nullptr;
2582 Node_List *split_bool_set = nullptr;
2583 Node_List *split_cex_set = nullptr;
2584 fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2585
2586 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2587 Node* old = extra_data_nodes.at(i);
2588 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2589 split_bool_set, split_cex_set, worklist, new_counter,
2590 mode);
2591 }
2592
2593 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2594 // the loop uses a condition set in the loop. The original IF probably
2595 // takes control from one or more OLD Regions (which in turn get from NEW
2596 // Regions). In any case, there will be a set of Phis for each merge point
2597 // from the IF up to where the original BOOL def exists the loop.
2598 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2599
2600 }
2601
2602 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2603 if (split_if_set) {
2604 while (split_if_set->size()) {
2605 Node *iff = split_if_set->pop();
2606 uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2607 if (iff->in(input)->is_Phi()) {
2608 Node *b = clone_iff(iff->in(input)->as_Phi());
2609 _igvn.replace_input_of(iff, input, b);
2610 }
2611 }
2612 }
2613 if (split_bool_set) {
2614 while (split_bool_set->size()) {
2615 Node *b = split_bool_set->pop();
2616 Node *phi = b->in(1);
2617 assert(phi->is_Phi(), "");
2618 CmpNode *cmp = clone_bool((PhiNode*) phi);
2619 _igvn.replace_input_of(b, 1, cmp);
2620 }
2621 }
2622 if (split_cex_set) {
2623 while (split_cex_set->size()) {
2624 Node *b = split_cex_set->pop();
2625 assert(b->in(0)->is_Region(), "");
2626 assert(b->in(1)->is_Phi(), "");
2627 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2628 split_up(b, b->in(0), nullptr);
2629 }
2630 }
2631 }
2632
2633 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2634 uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2635 Node_List*& split_bool_set, Node_List*& split_cex_set) {
2636 for(uint i = 0; i < body.size(); i++ ) {
2637 Node* old = body.at(i);
2638 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2639 split_bool_set, split_cex_set, worklist, new_counter,
2640 mode);
2641 }
2642 }
2643
2644 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2645 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2646 LoopNode* head = loop->_head->as_Loop();
2647 for(uint i = 0; i < body.size(); i++ ) {
2648 Node* old = body.at(i);
2649 if( !old->is_CFG() ) continue;
2650
2651 // Copy uses to a worklist, so I can munge the def-use info
2652 // with impunity.
2653 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2654 worklist.push(old->fast_out(j));
2655 }
2656
2657 while (worklist.size()) { // Visit all uses
2658 Node *use = worklist.pop();
2659 if (!has_node(use)) continue; // Ignore dead nodes
2660 IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2661 if (!loop->is_member(use_loop) && use->is_CFG()) {
2662 // Both OLD and USE are CFG nodes here.
2663 assert(use->is_Proj(), "" );
2664 Node* nnn = old_new[old->_idx];
2665
2666 Node* newuse = nullptr;
2667 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2668 CountedLoopNode* cl = head->as_CountedLoop();
2669 CountedLoopEndNode* cle = cl->loopexit();
2670 Node* cle_out = cle->proj_out_or_null(false);
2671 if (use == cle_out) {
2672 IfNode* le = cl->outer_loop_end();
2673 use = le->proj_out(false);
2674 use_loop = get_loop(use);
2675 if (mode == CloneIncludesStripMined) {
2676 nnn = old_new[le->_idx];
2677 } else {
2678 newuse = old_new[cle_out->_idx];
2679 }
2680 }
2681 }
2682 if (newuse == nullptr) {
2683 newuse = use->clone();
2684 }
2685
2686 // Clone the loop exit control projection
2687 if (C->do_vector_loop() && cm != nullptr) {
2688 cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2689 }
2690 newuse->set_req(0,nnn);
2691 _igvn.register_new_node_with_optimizer(newuse);
2692 set_loop(newuse, use_loop);
2693 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2694
2695 // We need a Region to merge the exit from the peeled body and the
2696 // exit from the old loop body.
2697 RegionNode *r = new RegionNode(3);
2698 uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2699 assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2700
2701 // The original user of 'use' uses 'r' instead.
2702 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2703 Node* useuse = use->last_out(l);
2704 _igvn.rehash_node_delayed(useuse);
2705 uint uses_found = 0;
2706 if (useuse->in(0) == use) {
2707 useuse->set_req(0, r);
2708 uses_found++;
2709 if (useuse->is_CFG()) {
2710 // This is not a dom_depth > dd_r because when new
2711 // control flow is constructed by a loop opt, a node and
2712 // its dominator can end up at the same dom_depth
2713 assert(dom_depth(useuse) >= dd_r, "");
2714 set_idom(useuse, r, dom_depth(useuse));
2715 }
2716 }
2717 for (uint k = 1; k < useuse->req(); k++) {
2718 if( useuse->in(k) == use ) {
2719 useuse->set_req(k, r);
2720 uses_found++;
2721 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2722 // This is not a dom_depth > dd_r because when new
2723 // control flow is constructed by a loop opt, a node
2724 // and its dominator can end up at the same dom_depth
2725 assert(dom_depth(useuse) >= dd_r , "");
2726 set_idom(useuse, r, dom_depth(useuse));
2727 }
2728 }
2729 }
2730 l -= uses_found; // we deleted 1 or more copies of this edge
2731 }
2732
2733 assert(use->is_Proj(), "loop exit should be projection");
2734 // lazy_replace() below moves all nodes that are:
2735 // - control dependent on the loop exit or
2736 // - have control set to the loop exit
2737 // below the post-loop merge point. lazy_replace() takes a dead control as first input. To make it
2738 // possible to use it, the loop exit projection is cloned and becomes the new exit projection. The initial one
2739 // becomes dead and is "replaced" by the region.
2740 Node* use_clone = use->clone();
2741 register_control(use_clone, use_loop, idom(use), dom_depth(use));
2742 // Now finish up 'r'
2743 r->set_req(1, newuse);
2744 r->set_req(2, use_clone);
2745 _igvn.register_new_node_with_optimizer(r);
2746 set_loop(r, use_loop);
2747 set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2748 lazy_replace(use, r);
2749 // Map the (cloned) old use to the new merge point
2750 old_new.map(use_clone->_idx, r);
2751 } // End of if a loop-exit test
2752 }
2753 }
2754 }
2755
2756 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2757 IdealLoopTree* parent, bool partial) {
2758 for(uint i = 0; i < body.size(); i++ ) {
2759 Node *old = body.at(i);
2760 Node *nnn = old_new[old->_idx];
2761 // Fix CFG/Loop controlling the new node
2762 if (has_ctrl(old)) {
2763 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2764 } else {
2765 set_loop(nnn, parent);
2766 if (old->outcnt() > 0) {
2767 Node* dom = idom(old);
2768 if (old_new[dom->_idx] != nullptr) {
2769 dom = old_new[dom->_idx];
2770 set_idom(nnn, dom, dd );
2771 }
2772 }
2773 }
2774 // Correct edges to the new node
2775 for (uint j = 0; j < nnn->req(); j++) {
2776 Node *n = nnn->in(j);
2777 if (n != nullptr) {
2778 IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2779 if (loop->is_member(old_in_loop)) {
2780 if (old_new[n->_idx] != nullptr) {
2781 nnn->set_req(j, old_new[n->_idx]);
2782 } else {
2783 assert(!body.contains(n), "");
2784 assert(partial, "node not cloned");
2785 }
2786 }
2787 }
2788 }
2789 _igvn.hash_find_insert(nnn);
2790 }
2791 }
2792
2793 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2794 for (uint i = 0; i < body.size(); i++) {
2795 Node* old = body.at(i);
2796 Node* nnn = old->clone();
2797 old_new.map(old->_idx, nnn);
2798 if (C->do_vector_loop() && cm != nullptr) {
2799 cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2800 }
2801 _igvn.register_new_node_with_optimizer(nnn);
2802 }
2803 }
2804
2805
2806 //---------------------- stride_of_possible_iv -------------------------------------
2807 // Looks for an iff/bool/comp with one operand of the compare
2808 // being a cycle involving an add and a phi,
2809 // with an optional truncation (left-shift followed by a right-shift)
2810 // of the add. Returns zero if not an iv.
2811 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2812 Node* trunc1 = nullptr;
2813 Node* trunc2 = nullptr;
2814 const TypeInteger* ttype = nullptr;
2815 if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
2816 return 0;
2817 }
2818 BoolNode* bl = iff->in(1)->as_Bool();
2819 Node* cmp = bl->in(1);
2820 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2821 return 0;
2822 }
2823 // Must have an invariant operand
2824 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2825 return 0;
2826 }
2827 Node* add2 = nullptr;
2828 Node* cmp1 = cmp->in(1);
2829 if (cmp1->is_Phi()) {
2830 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2831 Node* phi = cmp1;
2832 for (uint i = 1; i < phi->req(); i++) {
2833 Node* in = phi->in(i);
2834 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2835 &trunc1, &trunc2, &ttype, T_INT);
2836 if (add && add->in(1) == phi) {
2837 add2 = add->in(2);
2838 break;
2839 }
2840 }
2841 } else {
2842 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2843 Node* addtrunc = cmp1;
2844 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2845 &trunc1, &trunc2, &ttype, T_INT);
2846 if (add && add->in(1)->is_Phi()) {
2847 Node* phi = add->in(1);
2848 for (uint i = 1; i < phi->req(); i++) {
2849 if (phi->in(i) == addtrunc) {
2850 add2 = add->in(2);
2851 break;
2852 }
2853 }
2854 }
2855 }
2856 if (add2 != nullptr) {
2857 const TypeInt* add2t = _igvn.type(add2)->is_int();
2858 if (add2t->is_con()) {
2859 return add2t->get_con();
2860 }
2861 }
2862 return 0;
2863 }
2864
2865
2866 //---------------------- stay_in_loop -------------------------------------
2867 // Return the (unique) control output node that's in the loop (if it exists.)
2868 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2869 Node* unique = nullptr;
2870 if (!n) return nullptr;
2871 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2872 Node* use = n->fast_out(i);
2873 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2874 if (unique != nullptr) {
2875 return nullptr;
2876 }
2877 unique = use;
2878 }
2879 }
2880 return unique;
2881 }
2882
2883 //------------------------------ register_node -------------------------------------
2884 // Utility to register node "n" with PhaseIdealLoop
2885 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
2886 _igvn.register_new_node_with_optimizer(n);
2887 loop->_body.push(n);
2888 if (n->is_CFG()) {
2889 set_loop(n, loop);
2890 set_idom(n, pred, ddepth);
2891 } else {
2892 set_ctrl(n, pred);
2893 }
2894 }
2895
2896 //------------------------------ proj_clone -------------------------------------
2897 // Utility to create an if-projection
2898 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2899 ProjNode* c = p->clone()->as_Proj();
2900 c->set_req(0, iff);
2901 return c;
2902 }
2903
2904 //------------------------------ short_circuit_if -------------------------------------
2905 // Force the iff control output to be the live_proj
2906 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2907 guarantee(live_proj != nullptr, "null projection");
2908 int proj_con = live_proj->_con;
2909 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2910 Node* con = intcon(proj_con);
2911 if (iff) {
2912 iff->set_req(1, con);
2913 }
2914 return con;
2915 }
2916
2917 //------------------------------ insert_if_before_proj -------------------------------------
2918 // Insert a new if before an if projection (* - new node)
2919 //
2920 // before
2921 // if(test)
2922 // / \
2923 // v v
2924 // other-proj proj (arg)
2925 //
2926 // after
2927 // if(test)
2928 // / \
2929 // / v
2930 // | * proj-clone
2931 // v |
2932 // other-proj v
2933 // * new_if(relop(cmp[IU](left,right)))
2934 // / \
2935 // v v
2936 // * new-proj proj
2937 // (returned)
2938 //
2939 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2940 IfNode* iff = proj->in(0)->as_If();
2941 IdealLoopTree *loop = get_loop(proj);
2942 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2943 uint ddepth = dom_depth(proj);
2944
2945 _igvn.rehash_node_delayed(iff);
2946 _igvn.rehash_node_delayed(proj);
2947
2948 proj->set_req(0, nullptr); // temporary disconnect
2949 ProjNode* proj2 = proj_clone(proj, iff);
2950 register_node(proj2, loop, iff, ddepth);
2951
2952 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2953 register_node(cmp, loop, proj2, ddepth);
2954
2955 BoolNode* bol = new BoolNode(cmp, relop);
2956 register_node(bol, loop, proj2, ddepth);
2957
2958 int opcode = iff->Opcode();
2959 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2960 IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
2961 register_node(new_if, loop, proj2, ddepth);
2962
2963 proj->set_req(0, new_if); // reattach
2964 set_idom(proj, new_if, ddepth);
2965
2966 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2967 guarantee(new_exit != nullptr, "null exit node");
2968 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2969
2970 return new_exit;
2971 }
2972
2973 //------------------------------ insert_region_before_proj -------------------------------------
2974 // Insert a region before an if projection (* - new node)
2975 //
2976 // before
2977 // if(test)
2978 // / |
2979 // v |
2980 // proj v
2981 // other-proj
2982 //
2983 // after
2984 // if(test)
2985 // / |
2986 // v |
2987 // * proj-clone v
2988 // | other-proj
2989 // v
2990 // * new-region
2991 // |
2992 // v
2993 // * dum_if
2994 // / \
2995 // v \
2996 // * dum-proj v
2997 // proj
2998 //
2999 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3000 IfNode* iff = proj->in(0)->as_If();
3001 IdealLoopTree *loop = get_loop(proj);
3002 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3003 uint ddepth = dom_depth(proj);
3004
3005 _igvn.rehash_node_delayed(iff);
3006 _igvn.rehash_node_delayed(proj);
3007
3008 proj->set_req(0, nullptr); // temporary disconnect
3009 ProjNode* proj2 = proj_clone(proj, iff);
3010 register_node(proj2, loop, iff, ddepth);
3011
3012 RegionNode* reg = new RegionNode(2);
3013 reg->set_req(1, proj2);
3014 register_node(reg, loop, iff, ddepth);
3015
3016 IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3017 register_node(dum_if, loop, reg, ddepth);
3018
3019 proj->set_req(0, dum_if); // reattach
3020 set_idom(proj, dum_if, ddepth);
3021
3022 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3023 register_node(dum_proj, loop, dum_if, ddepth);
3024
3025 return reg;
3026 }
3027
3028 // Idea
3029 // ----
3030 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3031 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3032 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3033 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3034 // test alone instead:
3035 //
3036 // Before Partial Peeling:
3037 // Loop:
3038 // <peeled section>
3039 // Split off signed loop exit test
3040 // <-- CUT HERE -->
3041 // Unchanged unsigned loop exit test
3042 // <rest of unpeeled section>
3043 // goto Loop
3044 //
3045 // After Partial Peeling:
3046 // <cloned peeled section>
3047 // Cloned split off signed loop exit test
3048 // Loop:
3049 // Unchanged unsigned loop exit test
3050 // <rest of unpeeled section>
3051 // <peeled section>
3052 // Split off signed loop exit test
3053 // goto Loop
3054 //
3055 // Details
3056 // -------
3057 // Before:
3058 // if (i <u limit) Unsigned loop exit condition
3059 // / |
3060 // v v
3061 // exit-proj stay-in-loop-proj
3062 //
3063 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3064 // before the CmpU on the stay-in-loop path and keep both tests:
3065 //
3066 // if (i <u limit) Signed loop exit test
3067 // / |
3068 // / if (i <u limit) Unsigned loop exit test
3069 // / / |
3070 // v v v
3071 // exit-region stay-in-loop-proj
3072 //
3073 // Implementation
3074 // --------------
3075 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3076 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3077 // exit tests is preserved, and their loop nesting is correct.
3078 //
3079 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3080 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3081 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3082 //
3083 // if (stay-in-loop-const) Killed original unsigned loop exit test
3084 // / |
3085 // / v
3086 // / if (i < limit) Split off signed loop exit test
3087 // / / |
3088 // / / v
3089 // / / if (i <u limit) Cloned unsigned loop exit test
3090 // / / / |
3091 // v v v |
3092 // exit-region |
3093 // | |
3094 // dummy-if |
3095 // / | |
3096 // dead | |
3097 // v v
3098 // exit-proj stay-in-loop-proj
3099 //
3100 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3101 // loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3102 //
3103 // Requirements
3104 // ------------
3105 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3106 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3107 // Otherwise, we need to bail out (see comments in the code below).
3108 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3109 const bool Signed = true;
3110 const bool Unsigned = false;
3111
3112 BoolNode* bol = if_cmpu->in(1)->as_Bool();
3113 if (bol->_test._test != BoolTest::lt) {
3114 return nullptr;
3115 }
3116 CmpNode* cmpu = bol->in(1)->as_Cmp();
3117 assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3118
3119 int stride = stride_of_possible_iv(if_cmpu);
3120 if (stride == 0) {
3121 return nullptr;
3122 }
3123
3124 Node* lp_proj = stay_in_loop(if_cmpu, loop);
3125 guarantee(lp_proj != nullptr, "null loop node");
3126
3127 ProjNode* lp_continue = lp_proj->as_Proj();
3128 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3129 if (!lp_exit->is_IfFalse()) {
3130 // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3131 // We therefore can't add a single exit condition.
3132 return nullptr;
3133 }
3134 // The unsigned loop exit condition is
3135 // !(i <u limit)
3136 // = i >=u limit
3137 //
3138 // First, we note that for any x for which
3139 // 0 <= x <= INT_MAX
3140 // we can convert x to an unsigned int and still get the same guarantee:
3141 // 0 <= (uint) x <= INT_MAX = (uint) INT_MAX
3142 // 0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX (LEMMA)
3143 //
3144 // With that in mind, if
3145 // limit >= 0 (COND)
3146 // then the unsigned loop exit condition
3147 // i >=u limit (ULE)
3148 // is equivalent to
3149 // i < 0 || i >= limit (SLE-full)
3150 // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3151 // (uint) i >=u MAX_INT >= limit >= 0
3152 // or otherwise
3153 // i >= limit >= 0
3154 // holds due to (LEMMA).
3155 //
3156 // For completeness, a counterexample with limit < 0:
3157 // Assume i = -3 and limit = -2:
3158 // i < 0
3159 // -2 < 0
3160 // is true and thus also "i < 0 || i >= limit". But
3161 // i >=u limit
3162 // -3 >=u -2
3163 // is false.
3164 Node* limit = cmpu->in(2);
3165 const TypeInt* type_limit = _igvn.type(limit)->is_int();
3166 if (type_limit->_lo < 0) {
3167 return nullptr;
3168 }
3169
3170 // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3171 // stride < 0:
3172 // i < 0 (SLE = SLE-negative)
3173 // stride > 0:
3174 // i >= limit (SLE = SLE-positive)
3175 // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3176 //
3177 // Loop:
3178 // <peeled section>
3179 // i >= limit (SLE-positive)
3180 // <-- CUT HERE -->
3181 // i >=u limit (ULE)
3182 // <rest of unpeeled section>
3183 // goto Loop
3184 //
3185 // We exit the loop if:
3186 // (SLE) is true OR (ULE) is true
3187 // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3188 // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3189 // (SLE) IMPLIES (ULE)
3190 // This indeed holds when (COND) is given:
3191 // - stride > 0:
3192 // i >= limit // (SLE = SLE-positive)
3193 // i >= limit >= 0 // (COND)
3194 // i >=u limit >= 0 // (LEMMA)
3195 // which is the unsigned loop exit condition (ULE).
3196 // - stride < 0:
3197 // i < 0 // (SLE = SLE-negative)
3198 // (uint) i >u MAX_INT // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3199 // MAX_INT >= limit >= 0 // (COND)
3200 // MAX_INT >=u limit >= 0 // (LEMMA)
3201 // and thus from (NEG) and (LEMMA):
3202 // i >=u limit
3203 // which is the unsigned loop exit condition (ULE).
3204 //
3205 //
3206 // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3207 // <cloned peeled section>
3208 // i >= limit (SLE-positive)
3209 // Loop:
3210 // i >=u limit (ULE)
3211 // <rest of unpeeled section>
3212 // <peeled section>
3213 // i >= limit (SLE-positive)
3214 // goto Loop
3215 Node* rhs_cmpi;
3216 if (stride > 0) {
3217 rhs_cmpi = limit; // For i >= limit
3218 } else {
3219 rhs_cmpi = makecon(TypeInt::ZERO); // For i < 0
3220 }
3221 // Create a new region on the exit path
3222 RegionNode* reg = insert_region_before_proj(lp_exit);
3223 guarantee(reg != nullptr, "null region node");
3224
3225 // Clone the if-cmpu-true-false using a signed compare
3226 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3227 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3228 reg->add_req(cmpi_exit);
3229
3230 // Clone the if-cmpu-true-false
3231 BoolTest::mask rel_u = bol->_test._test;
3232 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3233 reg->add_req(cmpu_exit);
3234
3235 // Force original if to stay in loop.
3236 short_circuit_if(if_cmpu, lp_continue);
3237
3238 return cmpi_exit->in(0)->as_If();
3239 }
3240
3241 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3242 // Remove a previously inserted signed compare loop exit.
3243 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3244 Node* lp_proj = stay_in_loop(if_cmp, loop);
3245 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3246 stay_in_loop(lp_proj, loop)->is_If() &&
3247 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3248 Node* con = makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3249 if_cmp->set_req(1, con);
3250 }
3251
3252 //------------------------------ scheduled_nodelist -------------------------------------
3253 // Create a post order schedule of nodes that are in the
3254 // "member" set. The list is returned in "sched".
3255 // The first node in "sched" is the loop head, followed by
3256 // nodes which have no inputs in the "member" set, and then
3257 // followed by the nodes that have an immediate input dependence
3258 // on a node in "sched".
3259 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3260
3261 assert(member.test(loop->_head->_idx), "loop head must be in member set");
3262 VectorSet visited;
3263 Node_Stack nstack(loop->_body.size());
3264
3265 Node* n = loop->_head; // top of stack is cached in "n"
3266 uint idx = 0;
3267 visited.set(n->_idx);
3268
3269 // Initially push all with no inputs from within member set
3270 for(uint i = 0; i < loop->_body.size(); i++ ) {
3271 Node *elt = loop->_body.at(i);
3272 if (member.test(elt->_idx)) {
3273 bool found = false;
3274 for (uint j = 0; j < elt->req(); j++) {
3275 Node* def = elt->in(j);
3276 if (def && member.test(def->_idx) && def != elt) {
3277 found = true;
3278 break;
3279 }
3280 }
3281 if (!found && elt != loop->_head) {
3282 nstack.push(n, idx);
3283 n = elt;
3284 assert(!visited.test(n->_idx), "not seen yet");
3285 visited.set(n->_idx);
3286 }
3287 }
3288 }
3289
3290 // traverse out's that are in the member set
3291 while (true) {
3292 if (idx < n->outcnt()) {
3293 Node* use = n->raw_out(idx);
3294 idx++;
3295 if (!visited.test_set(use->_idx)) {
3296 if (member.test(use->_idx)) {
3297 nstack.push(n, idx);
3298 n = use;
3299 idx = 0;
3300 }
3301 }
3302 } else {
3303 // All outputs processed
3304 sched.push(n);
3305 if (nstack.is_empty()) break;
3306 n = nstack.node();
3307 idx = nstack.index();
3308 nstack.pop();
3309 }
3310 }
3311 }
3312
3313
3314 //------------------------------ has_use_in_set -------------------------------------
3315 // Has a use in the vector set
3316 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3317 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3318 Node* use = n->fast_out(j);
3319 if (vset.test(use->_idx)) {
3320 return true;
3321 }
3322 }
3323 return false;
3324 }
3325
3326
3327 //------------------------------ has_use_internal_to_set -------------------------------------
3328 // Has use internal to the vector set (ie. not in a phi at the loop head)
3329 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3330 Node* head = loop->_head;
3331 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3332 Node* use = n->fast_out(j);
3333 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3334 return true;
3335 }
3336 }
3337 return false;
3338 }
3339
3340
3341 //------------------------------ clone_for_use_outside_loop -------------------------------------
3342 // clone "n" for uses that are outside of loop
3343 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3344 int cloned = 0;
3345 assert(worklist.size() == 0, "should be empty");
3346 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3347 Node* use = n->fast_out(j);
3348 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3349 worklist.push(use);
3350 }
3351 }
3352
3353 if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3354 "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3355 return -1;
3356 }
3357
3358 while( worklist.size() ) {
3359 Node *use = worklist.pop();
3360 if (!has_node(use) || use->in(0) == C->top()) continue;
3361 uint j;
3362 for (j = 0; j < use->req(); j++) {
3363 if (use->in(j) == n) break;
3364 }
3365 assert(j < use->req(), "must be there");
3366
3367 // clone "n" and insert it between the inputs of "n" and the use outside the loop
3368 Node* n_clone = n->clone();
3369 _igvn.replace_input_of(use, j, n_clone);
3370 cloned++;
3371 Node* use_c;
3372 if (!use->is_Phi()) {
3373 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3374 } else {
3375 // Use in a phi is considered a use in the associated predecessor block
3376 use_c = use->in(0)->in(j);
3377 }
3378 set_ctrl(n_clone, use_c);
3379 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3380 get_loop(use_c)->_body.push(n_clone);
3381 _igvn.register_new_node_with_optimizer(n_clone);
3382 #ifndef PRODUCT
3383 if (TracePartialPeeling) {
3384 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3385 }
3386 #endif
3387 }
3388 return cloned;
3389 }
3390
3391
3392 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3393 // clone "n" for special uses that are in the not_peeled region.
3394 // If these def-uses occur in separate blocks, the code generator
3395 // marks the method as not compilable. For example, if a "BoolNode"
3396 // is in a different basic block than the "IfNode" that uses it, then
3397 // the compilation is aborted in the code generator.
3398 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3399 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3400 if (n->is_Phi() || n->is_Load()) {
3401 return;
3402 }
3403 assert(worklist.size() == 0, "should be empty");
3404 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3405 Node* use = n->fast_out(j);
3406 if ( not_peel.test(use->_idx) &&
3407 (use->is_If() || use->is_CMove() || use->is_Bool() || use->is_OpaqueInitializedAssertionPredicate()) &&
3408 use->in(1) == n) {
3409 worklist.push(use);
3410 }
3411 }
3412 if (worklist.size() > 0) {
3413 // clone "n" and insert it between inputs of "n" and the use
3414 Node* n_clone = n->clone();
3415 loop->_body.push(n_clone);
3416 _igvn.register_new_node_with_optimizer(n_clone);
3417 set_ctrl(n_clone, get_ctrl(n));
3418 sink_list.push(n_clone);
3419 not_peel.set(n_clone->_idx);
3420 #ifndef PRODUCT
3421 if (TracePartialPeeling) {
3422 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3423 }
3424 #endif
3425 while( worklist.size() ) {
3426 Node *use = worklist.pop();
3427 _igvn.rehash_node_delayed(use);
3428 for (uint j = 1; j < use->req(); j++) {
3429 if (use->in(j) == n) {
3430 use->set_req(j, n_clone);
3431 }
3432 }
3433 }
3434 }
3435 }
3436
3437
3438 //------------------------------ insert_phi_for_loop -------------------------------------
3439 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3440 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3441 Node *phi = PhiNode::make(lp, back_edge_val);
3442 phi->set_req(LoopNode::EntryControl, lp_entry_val);
3443 // Use existing phi if it already exists
3444 Node *hit = _igvn.hash_find_insert(phi);
3445 if( hit == nullptr ) {
3446 _igvn.register_new_node_with_optimizer(phi);
3447 set_ctrl(phi, lp);
3448 } else {
3449 // Remove the new phi from the graph and use the hit
3450 _igvn.remove_dead_node(phi);
3451 phi = hit;
3452 }
3453 _igvn.replace_input_of(use, idx, phi);
3454 }
3455
3456 #ifdef ASSERT
3457 //------------------------------ is_valid_loop_partition -------------------------------------
3458 // Validate the loop partition sets: peel and not_peel
3459 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3460 VectorSet& not_peel ) {
3461 uint i;
3462 // Check that peel_list entries are in the peel set
3463 for (i = 0; i < peel_list.size(); i++) {
3464 if (!peel.test(peel_list.at(i)->_idx)) {
3465 return false;
3466 }
3467 }
3468 // Check at loop members are in one of peel set or not_peel set
3469 for (i = 0; i < loop->_body.size(); i++ ) {
3470 Node *def = loop->_body.at(i);
3471 uint di = def->_idx;
3472 // Check that peel set elements are in peel_list
3473 if (peel.test(di)) {
3474 if (not_peel.test(di)) {
3475 return false;
3476 }
3477 // Must be in peel_list also
3478 bool found = false;
3479 for (uint j = 0; j < peel_list.size(); j++) {
3480 if (peel_list.at(j)->_idx == di) {
3481 found = true;
3482 break;
3483 }
3484 }
3485 if (!found) {
3486 return false;
3487 }
3488 } else if (not_peel.test(di)) {
3489 if (peel.test(di)) {
3490 return false;
3491 }
3492 } else {
3493 return false;
3494 }
3495 }
3496 return true;
3497 }
3498
3499 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3500 // Ensure a use outside of loop is of the right form
3501 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3502 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3503 return (use->is_Phi() &&
3504 use_c->is_Region() && use_c->req() == 3 &&
3505 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3506 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3507 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3508 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3509 }
3510
3511 //------------------------------ is_valid_clone_loop_form -------------------------------------
3512 // Ensure that all uses outside of loop are of the right form
3513 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3514 uint orig_exit_idx, uint clone_exit_idx) {
3515 uint len = peel_list.size();
3516 for (uint i = 0; i < len; i++) {
3517 Node *def = peel_list.at(i);
3518
3519 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3520 Node *use = def->fast_out(j);
3521 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3522 if (!loop->is_member(get_loop(use_c))) {
3523 // use is not in the loop, check for correct structure
3524 if (use->in(0) == def) {
3525 // Okay
3526 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3527 return false;
3528 }
3529 }
3530 }
3531 }
3532 return true;
3533 }
3534 #endif
3535
3536 //------------------------------ partial_peel -------------------------------------
3537 // Partially peel (aka loop rotation) the top portion of a loop (called
3538 // the peel section below) by cloning it and placing one copy just before
3539 // the new loop head and the other copy at the bottom of the new loop.
3540 //
3541 // before after where it came from
3542 //
3543 // stmt1 stmt1
3544 // loop: stmt2 clone
3545 // stmt2 if condA goto exitA clone
3546 // if condA goto exitA new_loop: new
3547 // stmt3 stmt3 clone
3548 // if !condB goto loop if condB goto exitB clone
3549 // exitB: stmt2 orig
3550 // stmt4 if !condA goto new_loop orig
3551 // exitA: goto exitA
3552 // exitB:
3553 // stmt4
3554 // exitA:
3555 //
3556 // Step 1: find the cut point: an exit test on probable
3557 // induction variable.
3558 // Step 2: schedule (with cloning) operations in the peel
3559 // section that can be executed after the cut into
3560 // the section that is not peeled. This may need
3561 // to clone operations into exit blocks. For
3562 // instance, a reference to A[i] in the not-peel
3563 // section and a reference to B[i] in an exit block
3564 // may cause a left-shift of i by 2 to be placed
3565 // in the peel block. This step will clone the left
3566 // shift into the exit block and sink the left shift
3567 // from the peel to the not-peel section.
3568 // Step 3: clone the loop, retarget the control, and insert
3569 // phis for values that are live across the new loop
3570 // head. This is very dependent on the graph structure
3571 // from clone_loop. It creates region nodes for
3572 // exit control and associated phi nodes for values
3573 // flow out of the loop through that exit. The region
3574 // node is dominated by the clone's control projection.
3575 // So the clone's peel section is placed before the
3576 // new loop head, and the clone's not-peel section is
3577 // forms the top part of the new loop. The original
3578 // peel section forms the tail of the new loop.
3579 // Step 4: update the dominator tree and recompute the
3580 // dominator depth.
3581 //
3582 // orig
3583 //
3584 // stmt1
3585 // |
3586 // v
3587 // predicates
3588 // |
3589 // v
3590 // loop<----+
3591 // | |
3592 // stmt2 |
3593 // | |
3594 // v |
3595 // ifA |
3596 // / | |
3597 // v v |
3598 // false true ^ <-- last_peel
3599 // / | |
3600 // / ===|==cut |
3601 // / stmt3 | <-- first_not_peel
3602 // / | |
3603 // | v |
3604 // v ifB |
3605 // exitA: / \ |
3606 // / \ |
3607 // v v |
3608 // false true |
3609 // / \ |
3610 // / ----+
3611 // |
3612 // v
3613 // exitB:
3614 // stmt4
3615 //
3616 //
3617 // after clone loop
3618 //
3619 // stmt1
3620 // |
3621 // v
3622 // predicates
3623 // / \
3624 // clone / \ orig
3625 // / \
3626 // / \
3627 // v v
3628 // +---->loop loop<----+
3629 // | | | |
3630 // | stmt2 stmt2 |
3631 // | | | |
3632 // | v v |
3633 // | ifA ifA |
3634 // | | \ / | |
3635 // | v v v v |
3636 // ^ true false false true ^ <-- last_peel
3637 // | | ^ \ / | |
3638 // | cut==|== \ \ / ===|==cut |
3639 // | stmt3 \ \ / stmt3 | <-- first_not_peel
3640 // | | dom | | | |
3641 // | v \ 1v v2 v |
3642 // | ifB regionA ifB |
3643 // | / \ | / \ |
3644 // | / \ v / \ |
3645 // | v v exitA: v v |
3646 // | true false false true |
3647 // | / ^ \ / \ |
3648 // +---- \ \ / ----+
3649 // dom \ /
3650 // \ 1v v2
3651 // regionB
3652 // |
3653 // v
3654 // exitB:
3655 // stmt4
3656 //
3657 //
3658 // after partial peel
3659 //
3660 // stmt1
3661 // |
3662 // v
3663 // predicates
3664 // /
3665 // clone / orig
3666 // / TOP
3667 // / \
3668 // v v
3669 // TOP->loop loop----+
3670 // | | |
3671 // stmt2 stmt2 |
3672 // | | |
3673 // v v |
3674 // ifA ifA |
3675 // | \ / | |
3676 // v v v v |
3677 // true false false true | <-- last_peel
3678 // | ^ \ / +------|---+
3679 // +->newloop \ \ / === ==cut | |
3680 // | stmt3 \ \ / TOP | |
3681 // | | dom | | stmt3 | | <-- first_not_peel
3682 // | v \ 1v v2 v | |
3683 // | ifB regionA ifB ^ v
3684 // | / \ | / \ | |
3685 // | / \ v / \ | |
3686 // | v v exitA: v v | |
3687 // | true false false true | |
3688 // | / ^ \ / \ | |
3689 // | | \ \ / v | |
3690 // | | dom \ / TOP | |
3691 // | | \ 1v v2 | |
3692 // ^ v regionB | |
3693 // | | | | |
3694 // | | v ^ v
3695 // | | exitB: | |
3696 // | | stmt4 | |
3697 // | +------------>-----------------+ |
3698 // | |
3699 // +-----------------<---------------------+
3700 //
3701 //
3702 // final graph
3703 //
3704 // stmt1
3705 // |
3706 // v
3707 // predicates
3708 // |
3709 // v
3710 // stmt2 clone
3711 // |
3712 // v
3713 // ........> ifA clone
3714 // : / |
3715 // dom / |
3716 // : v v
3717 // : false true
3718 // : | |
3719 // : | v
3720 // : | newloop<-----+
3721 // : | | |
3722 // : | stmt3 clone |
3723 // : | | |
3724 // : | v |
3725 // : | ifB |
3726 // : | / \ |
3727 // : | v v |
3728 // : | false true |
3729 // : | | | |
3730 // : | v stmt2 |
3731 // : | exitB: | |
3732 // : | stmt4 v |
3733 // : | ifA orig |
3734 // : | / \ |
3735 // : | / \ |
3736 // : | v v |
3737 // : | false true |
3738 // : | / \ |
3739 // : v v -----+
3740 // RegionA
3741 // |
3742 // v
3743 // exitA
3744 //
3745 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3746
3747 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3748 if (!loop->_head->is_Loop()) {
3749 return false;
3750 }
3751 LoopNode *head = loop->_head->as_Loop();
3752
3753 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3754 return false;
3755 }
3756
3757 // Check for complex exit control
3758 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3759 Node *n = loop->_body.at(ii);
3760 int opc = n->Opcode();
3761 if (n->is_Call() ||
3762 opc == Op_Catch ||
3763 opc == Op_CatchProj ||
3764 opc == Op_Jump ||
3765 opc == Op_JumpProj) {
3766 #ifndef PRODUCT
3767 if (TracePartialPeeling) {
3768 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3769 }
3770 #endif
3771 return false;
3772 }
3773 }
3774
3775 int dd = dom_depth(head);
3776
3777 // Step 1: find cut point
3778
3779 // Walk up dominators to loop head looking for first loop exit
3780 // which is executed on every path thru loop.
3781 IfNode *peel_if = nullptr;
3782 IfNode *peel_if_cmpu = nullptr;
3783
3784 Node *iff = loop->tail();
3785 while (iff != head) {
3786 if (iff->is_If()) {
3787 Node *ctrl = get_ctrl(iff->in(1));
3788 if (ctrl->is_top()) return false; // Dead test on live IF.
3789 // If loop-varying exit-test, check for induction variable
3790 if (loop->is_member(get_loop(ctrl)) &&
3791 loop->is_loop_exit(iff) &&
3792 is_possible_iv_test(iff)) {
3793 Node* cmp = iff->in(1)->in(1);
3794 if (cmp->Opcode() == Op_CmpI) {
3795 peel_if = iff->as_If();
3796 } else {
3797 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3798 peel_if_cmpu = iff->as_If();
3799 }
3800 }
3801 }
3802 iff = idom(iff);
3803 }
3804
3805 // Prefer signed compare over unsigned compare.
3806 IfNode* new_peel_if = nullptr;
3807 if (peel_if == nullptr) {
3808 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
3809 return false; // No peel point found
3810 }
3811 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3812 if (new_peel_if == nullptr) {
3813 return false; // No peel point found
3814 }
3815 peel_if = new_peel_if;
3816 }
3817 Node* last_peel = stay_in_loop(peel_if, loop);
3818 Node* first_not_peeled = stay_in_loop(last_peel, loop);
3819 if (first_not_peeled == nullptr || first_not_peeled == head) {
3820 return false;
3821 }
3822
3823 #ifndef PRODUCT
3824 if (TraceLoopOpts) {
3825 tty->print("PartialPeel ");
3826 loop->dump_head();
3827 }
3828
3829 if (TracePartialPeeling) {
3830 tty->print_cr("before partial peel one iteration");
3831 Node_List wl;
3832 Node* t = head->in(2);
3833 while (true) {
3834 wl.push(t);
3835 if (t == head) break;
3836 t = idom(t);
3837 }
3838 while (wl.size() > 0) {
3839 Node* tt = wl.pop();
3840 tt->dump();
3841 if (tt == last_peel) tty->print_cr("-- cut --");
3842 }
3843 }
3844 #endif
3845
3846 C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
3847
3848 VectorSet peel;
3849 VectorSet not_peel;
3850 Node_List peel_list;
3851 Node_List worklist;
3852 Node_List sink_list;
3853
3854 uint estimate = loop->est_loop_clone_sz(1);
3855 if (exceeding_node_budget(estimate)) {
3856 return false;
3857 }
3858
3859 // Set of cfg nodes to peel are those that are executable from
3860 // the head through last_peel.
3861 assert(worklist.size() == 0, "should be empty");
3862 worklist.push(head);
3863 peel.set(head->_idx);
3864 while (worklist.size() > 0) {
3865 Node *n = worklist.pop();
3866 if (n != last_peel) {
3867 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3868 Node* use = n->fast_out(j);
3869 if (use->is_CFG() &&
3870 loop->is_member(get_loop(use)) &&
3871 !peel.test_set(use->_idx)) {
3872 worklist.push(use);
3873 }
3874 }
3875 }
3876 }
3877
3878 // Set of non-cfg nodes to peel are those that are control
3879 // dependent on the cfg nodes.
3880 for (uint i = 0; i < loop->_body.size(); i++) {
3881 Node *n = loop->_body.at(i);
3882 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3883 if (peel.test(n_c->_idx)) {
3884 peel.set(n->_idx);
3885 } else {
3886 not_peel.set(n->_idx);
3887 }
3888 }
3889
3890 // Step 2: move operations from the peeled section down into the
3891 // not-peeled section
3892
3893 // Get a post order schedule of nodes in the peel region
3894 // Result in right-most operand.
3895 scheduled_nodelist(loop, peel, peel_list);
3896
3897 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3898
3899 // For future check for too many new phis
3900 uint old_phi_cnt = 0;
3901 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3902 Node* use = head->fast_out(j);
3903 if (use->is_Phi()) old_phi_cnt++;
3904 }
3905
3906 #ifndef PRODUCT
3907 if (TracePartialPeeling) {
3908 tty->print_cr("\npeeled list");
3909 }
3910 #endif
3911
3912 // Evacuate nodes in peel region into the not_peeled region if possible
3913 bool too_many_clones = false;
3914 uint new_phi_cnt = 0;
3915 uint cloned_for_outside_use = 0;
3916 for (uint i = 0; i < peel_list.size();) {
3917 Node* n = peel_list.at(i);
3918 #ifndef PRODUCT
3919 if (TracePartialPeeling) n->dump();
3920 #endif
3921 bool incr = true;
3922 if (!n->is_CFG()) {
3923 if (has_use_in_set(n, not_peel)) {
3924 // If not used internal to the peeled region,
3925 // move "n" from peeled to not_peeled region.
3926 if (!has_use_internal_to_set(n, peel, loop)) {
3927 // if not pinned and not a load (which maybe anti-dependent on a store)
3928 // and not a CMove (Matcher expects only bool->cmove).
3929 if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
3930 int new_clones = clone_for_use_outside_loop(loop, n, worklist);
3931 if (C->failing()) return false;
3932 if (new_clones == -1) {
3933 too_many_clones = true;
3934 break;
3935 }
3936 cloned_for_outside_use += new_clones;
3937 sink_list.push(n);
3938 peel.remove(n->_idx);
3939 not_peel.set(n->_idx);
3940 peel_list.remove(i);
3941 incr = false;
3942 #ifndef PRODUCT
3943 if (TracePartialPeeling) {
3944 tty->print_cr("sink to not_peeled region: %d newbb: %d",
3945 n->_idx, get_ctrl(n)->_idx);
3946 }
3947 #endif
3948 }
3949 } else {
3950 // Otherwise check for special def-use cases that span
3951 // the peel/not_peel boundary such as bool->if
3952 clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3953 new_phi_cnt++;
3954 }
3955 }
3956 }
3957 if (incr) i++;
3958 }
3959
3960 estimate += cloned_for_outside_use + new_phi_cnt;
3961 bool exceed_node_budget = !may_require_nodes(estimate);
3962 bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3963
3964 if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
3965 #ifndef PRODUCT
3966 if (TracePartialPeeling && exceed_phi_limit) {
3967 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
3968 new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
3969 }
3970 #endif
3971 if (new_peel_if != nullptr) {
3972 remove_cmpi_loop_exit(new_peel_if, loop);
3973 }
3974 // Inhibit more partial peeling on this loop
3975 assert(!head->is_partial_peel_loop(), "not partial peeled");
3976 head->mark_partial_peel_failed();
3977 if (cloned_for_outside_use > 0) {
3978 // Terminate this round of loop opts because
3979 // the graph outside this loop was changed.
3980 C->set_major_progress();
3981 return true;
3982 }
3983 return false;
3984 }
3985
3986 // Step 3: clone loop, retarget control, and insert new phis
3987
3988 // Create new loop head for new phis and to hang
3989 // the nodes being moved (sinked) from the peel region.
3990 LoopNode* new_head = new LoopNode(last_peel, last_peel);
3991 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3992 _igvn.register_new_node_with_optimizer(new_head);
3993 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3994 _igvn.replace_input_of(first_not_peeled, 0, new_head);
3995 set_loop(new_head, loop);
3996 loop->_body.push(new_head);
3997 not_peel.set(new_head->_idx);
3998 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3999 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
4000
4001 while (sink_list.size() > 0) {
4002 Node* n = sink_list.pop();
4003 set_ctrl(n, new_head);
4004 }
4005
4006 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4007
4008 clone_loop(loop, old_new, dd, IgnoreStripMined);
4009
4010 const uint clone_exit_idx = 1;
4011 const uint orig_exit_idx = 2;
4012 assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4013
4014 Node* head_clone = old_new[head->_idx];
4015 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
4016 Node* orig_tail_clone = head_clone->in(2);
4017
4018 // Add phi if "def" node is in peel set and "use" is not
4019
4020 for (uint i = 0; i < peel_list.size(); i++) {
4021 Node *def = peel_list.at(i);
4022 if (!def->is_CFG()) {
4023 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4024 Node *use = def->fast_out(j);
4025 if (has_node(use) && use->in(0) != C->top() &&
4026 (!peel.test(use->_idx) ||
4027 (use->is_Phi() && use->in(0) == head)) ) {
4028 worklist.push(use);
4029 }
4030 }
4031 while( worklist.size() ) {
4032 Node *use = worklist.pop();
4033 for (uint j = 1; j < use->req(); j++) {
4034 Node* n = use->in(j);
4035 if (n == def) {
4036
4037 // "def" is in peel set, "use" is not in peel set
4038 // or "use" is in the entry boundary (a phi) of the peel set
4039
4040 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4041
4042 if ( loop->is_member(get_loop( use_c )) ) {
4043 // use is in loop
4044 if (old_new[use->_idx] != nullptr) { // null for dead code
4045 Node* use_clone = old_new[use->_idx];
4046 _igvn.replace_input_of(use, j, C->top());
4047 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4048 }
4049 } else {
4050 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4051 // use is not in the loop, check if the live range includes the cut
4052 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4053 if (not_peel.test(lp_if->_idx)) {
4054 assert(j == orig_exit_idx, "use from original loop");
4055 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4056 }
4057 }
4058 }
4059 }
4060 }
4061 }
4062 }
4063
4064 // Step 3b: retarget control
4065
4066 // Redirect control to the new loop head if a cloned node in
4067 // the not_peeled region has control that points into the peeled region.
4068 // This necessary because the cloned peeled region will be outside
4069 // the loop.
4070 // from to
4071 // cloned-peeled <---+
4072 // new_head_clone: | <--+
4073 // cloned-not_peeled in(0) in(0)
4074 // orig-peeled
4075
4076 for (uint i = 0; i < loop->_body.size(); i++) {
4077 Node *n = loop->_body.at(i);
4078 if (!n->is_CFG() && n->in(0) != nullptr &&
4079 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4080 Node* n_clone = old_new[n->_idx];
4081 if (n_clone->depends_only_on_test()) {
4082 // Pin array access nodes: control is updated here to the loop head. If, after some transformations, the
4083 // backedge is removed, an array load could become dependent on a condition that's not a range check for that
4084 // access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
4085 // floating above its range check.
4086 Node* pinned_clone = n_clone->pin_array_access_node();
4087 if (pinned_clone != nullptr) {
4088 register_new_node_with_ctrl_of(pinned_clone, n_clone);
4089 old_new.map(n->_idx, pinned_clone);
4090 _igvn.replace_node(n_clone, pinned_clone);
4091 n_clone = pinned_clone;
4092 }
4093 }
4094 _igvn.replace_input_of(n_clone, 0, new_head_clone);
4095 }
4096 }
4097
4098 // Backedge of the surviving new_head (the clone) is original last_peel
4099 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4100
4101 // Cut first node in original not_peel set
4102 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
4103 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
4104 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
4105
4106 // Copy head_clone back-branch info to original head
4107 // and remove original head's loop entry and
4108 // clone head's back-branch
4109 _igvn.rehash_node_delayed(head); // Multiple edge updates
4110 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
4111 head->set_req(LoopNode::LoopBackControl, C->top());
4112 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4113
4114 // Similarly modify the phis
4115 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4116 Node* use = head->fast_out(k);
4117 if (use->is_Phi() && use->outcnt() > 0) {
4118 Node* use_clone = old_new[use->_idx];
4119 _igvn.rehash_node_delayed(use); // Multiple edge updates
4120 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
4121 use->set_req(LoopNode::LoopBackControl, C->top());
4122 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4123 }
4124 }
4125
4126 // Step 4: update dominator tree and dominator depth
4127
4128 set_idom(head, orig_tail_clone, dd);
4129 recompute_dom_depth();
4130
4131 // Inhibit more partial peeling on this loop
4132 new_head_clone->set_partial_peel_loop();
4133 C->set_major_progress();
4134 loop->record_for_igvn();
4135
4136 #ifndef PRODUCT
4137 if (TracePartialPeeling) {
4138 tty->print_cr("\nafter partial peel one iteration");
4139 Node_List wl;
4140 Node* t = last_peel;
4141 while (true) {
4142 wl.push(t);
4143 if (t == head_clone) break;
4144 t = idom(t);
4145 }
4146 while (wl.size() > 0) {
4147 Node* tt = wl.pop();
4148 if (tt == head) tty->print_cr("orig head");
4149 else if (tt == new_head_clone) tty->print_cr("new head");
4150 else if (tt == head_clone) tty->print_cr("clone head");
4151 tt->dump();
4152 }
4153 }
4154 #endif
4155
4156 C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4157
4158 return true;
4159 }
4160
4161 // Transform:
4162 //
4163 // loop<-----------------+
4164 // | |
4165 // stmt1 stmt2 .. stmtn |
4166 // | | | |
4167 // \ | / |
4168 // v v v |
4169 // region |
4170 // | |
4171 // shared_stmt |
4172 // | |
4173 // v |
4174 // if |
4175 // / \ |
4176 // | -----------+
4177 // v
4178 //
4179 // into:
4180 //
4181 // loop<-------------------+
4182 // | |
4183 // v |
4184 // +->loop |
4185 // | | |
4186 // | stmt1 stmt2 .. stmtn |
4187 // | | | | |
4188 // | | \ / |
4189 // | | v v |
4190 // | | region1 |
4191 // | | | |
4192 // | shared_stmt shared_stmt |
4193 // | | | |
4194 // | v v |
4195 // | if if |
4196 // | /\ / \ |
4197 // +-- | | -------+
4198 // \ /
4199 // v v
4200 // region2
4201 //
4202 // (region2 is shown to merge mirrored projections of the loop exit
4203 // ifs to make the diagram clearer but they really merge the same
4204 // projection)
4205 //
4206 // Conditions for this transformation to trigger:
4207 // - the path through stmt1 is frequent enough
4208 // - the inner loop will be turned into a counted loop after transformation
4209 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4210 if (!DuplicateBackedge) {
4211 return false;
4212 }
4213 assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4214 if (!loop->_head->is_Loop()) {
4215 return false;
4216 }
4217
4218 uint estimate = loop->est_loop_clone_sz(1);
4219 if (exceeding_node_budget(estimate)) {
4220 return false;
4221 }
4222
4223 LoopNode *head = loop->_head->as_Loop();
4224
4225 Node* region = nullptr;
4226 IfNode* exit_test = nullptr;
4227 uint inner;
4228 float f;
4229 if (StressDuplicateBackedge) {
4230 if (head->is_strip_mined()) {
4231 return false;
4232 }
4233 Node* c = head->in(LoopNode::LoopBackControl);
4234
4235 while (c != head) {
4236 if (c->is_Region()) {
4237 region = c;
4238 }
4239 c = idom(c);
4240 }
4241
4242 if (region == nullptr) {
4243 return false;
4244 }
4245
4246 inner = 1;
4247 } else {
4248 // Is the shape of the loop that of a counted loop...
4249 Node* back_control = loop_exit_control(head, loop);
4250 if (back_control == nullptr) {
4251 return false;
4252 }
4253
4254 BoolTest::mask bt = BoolTest::illegal;
4255 float cl_prob = 0;
4256 Node* incr = nullptr;
4257 Node* limit = nullptr;
4258 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4259 if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4260 return false;
4261 }
4262
4263 // With an extra phi for the candidate iv?
4264 // Or the region node is the loop head
4265 if (!incr->is_Phi() || incr->in(0) == head) {
4266 return false;
4267 }
4268
4269 PathFrequency pf(head, this);
4270 region = incr->in(0);
4271
4272 // Go over all paths for the extra phi's region and see if that
4273 // path is frequent enough and would match the expected iv shape
4274 // if the extra phi is removed
4275 inner = 0;
4276 for (uint i = 1; i < incr->req(); ++i) {
4277 Node* in = incr->in(i);
4278 Node* trunc1 = nullptr;
4279 Node* trunc2 = nullptr;
4280 const TypeInteger* iv_trunc_t = nullptr;
4281 Node* orig_in = in;
4282 if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4283 continue;
4284 }
4285 assert(in->Opcode() == Op_AddI, "wrong increment code");
4286 Node* xphi = nullptr;
4287 Node* stride = loop_iv_stride(in, xphi);
4288
4289 if (stride == nullptr) {
4290 continue;
4291 }
4292
4293 PhiNode* phi = loop_iv_phi(xphi, nullptr, head);
4294 if (phi == nullptr ||
4295 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4296 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4297 return false;
4298 }
4299
4300 f = pf.to(region->in(i));
4301 if (f > 0.5) {
4302 inner = i;
4303 break;
4304 }
4305 }
4306
4307 if (inner == 0) {
4308 return false;
4309 }
4310
4311 exit_test = back_control->in(0)->as_If();
4312 }
4313
4314 if (idom(region)->is_Catch()) {
4315 return false;
4316 }
4317
4318 // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4319 Unique_Node_List wq;
4320 wq.push(head->in(LoopNode::LoopBackControl));
4321 for (uint i = 0; i < wq.size(); i++) {
4322 Node* c = wq.at(i);
4323 assert(get_loop(c) == loop, "not in the right loop?");
4324 if (c->is_Region()) {
4325 if (c != region) {
4326 for (uint j = 1; j < c->req(); ++j) {
4327 wq.push(c->in(j));
4328 }
4329 }
4330 } else {
4331 wq.push(c->in(0));
4332 }
4333 assert(!is_strict_dominator(c, region), "shouldn't go above region");
4334 }
4335
4336 Node* region_dom = idom(region);
4337
4338 // Can't do the transformation if this would cause a membar pair to
4339 // be split
4340 for (uint i = 0; i < wq.size(); i++) {
4341 Node* c = wq.at(i);
4342 if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4343 assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4344 if (!wq.member(c->as_MemBar()->leading_membar())) {
4345 return false;
4346 }
4347 }
4348 }
4349 C->print_method(PHASE_BEFORE_DUPLICATE_LOOP_BACKEDGE, 4, head);
4350
4351 // Collect data nodes that need to be clones as well
4352 int dd = dom_depth(head);
4353
4354 for (uint i = 0; i < loop->_body.size(); ++i) {
4355 Node* n = loop->_body.at(i);
4356 if (has_ctrl(n)) {
4357 Node* c = get_ctrl(n);
4358 if (wq.member(c)) {
4359 wq.push(n);
4360 }
4361 } else {
4362 set_idom(n, idom(n), dd);
4363 }
4364 }
4365
4366 // clone shared_stmt
4367 clone_loop_body(wq, old_new, nullptr);
4368
4369 Node* region_clone = old_new[region->_idx];
4370 region_clone->set_req(inner, C->top());
4371 set_idom(region, region->in(inner), dd);
4372
4373 // Prepare the outer loop
4374 Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4375 register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4376 _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4377 set_idom(head, outer_head, dd);
4378
4379 fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4380
4381 // Make one of the shared_stmt copies only reachable from stmt1, the
4382 // other only from stmt2..stmtn.
4383 Node* dom = nullptr;
4384 for (uint i = 1; i < region->req(); ++i) {
4385 if (i != inner) {
4386 _igvn.replace_input_of(region, i, C->top());
4387 }
4388 Node* in = region_clone->in(i);
4389 if (in->is_top()) {
4390 continue;
4391 }
4392 if (dom == nullptr) {
4393 dom = in;
4394 } else {
4395 dom = dom_lca(dom, in);
4396 }
4397 }
4398
4399 set_idom(region_clone, dom, dd);
4400
4401 // Set up the outer loop
4402 for (uint i = 0; i < head->outcnt(); i++) {
4403 Node* u = head->raw_out(i);
4404 if (u->is_Phi()) {
4405 Node* outer_phi = u->clone();
4406 outer_phi->set_req(0, outer_head);
4407 Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4408 if (backedge == nullptr) {
4409 backedge = u->in(LoopNode::LoopBackControl);
4410 }
4411 outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4412 register_new_node(outer_phi, outer_head);
4413 _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4414 }
4415 }
4416
4417 // create control and data nodes for out of loop uses (including region2)
4418 Node_List worklist;
4419 uint new_counter = C->unique();
4420 fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4421
4422 Node_List *split_if_set = nullptr;
4423 Node_List *split_bool_set = nullptr;
4424 Node_List *split_cex_set = nullptr;
4425 fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4426 split_if_set, split_bool_set, split_cex_set);
4427
4428 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4429
4430 if (exit_test != nullptr) {
4431 float cnt = exit_test->_fcnt;
4432 if (cnt != COUNT_UNKNOWN) {
4433 exit_test->_fcnt = cnt * f;
4434 old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4435 }
4436 }
4437
4438 C->set_major_progress();
4439
4440 C->print_method(PHASE_AFTER_DUPLICATE_LOOP_BACKEDGE, 4, outer_head);
4441
4442 return true;
4443 }
4444
4445 // AutoVectorize the loop: replace scalar ops with vector ops.
4446 PhaseIdealLoop::AutoVectorizeStatus
4447 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4448 // Counted loop only
4449 if (!lpt->is_counted()) {
4450 return AutoVectorizeStatus::Impossible;
4451 }
4452
4453 // Main-loop only
4454 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4455 if (!cl->is_main_loop()) {
4456 return AutoVectorizeStatus::Impossible;
4457 }
4458
4459 VLoop vloop(lpt, false);
4460 if (!vloop.check_preconditions()) {
4461 return AutoVectorizeStatus::TriedAndFailed;
4462 }
4463
4464 // Ensure the shared data is cleared before each use
4465 vshared.clear();
4466
4467 const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4468 if (!vloop_analyzer.success()) {
4469 return AutoVectorizeStatus::TriedAndFailed;
4470 }
4471
4472 SuperWord sw(vloop_analyzer);
4473 if (!sw.transform_loop()) {
4474 return AutoVectorizeStatus::TriedAndFailed;
4475 }
4476
4477 return AutoVectorizeStatus::Success;
4478 }
4479
4480 // Just before insert_pre_post_loops, we can multiversion the loop:
4481 //
4482 // multiversion_if
4483 // | |
4484 // fast_loop slow_loop
4485 //
4486 // In the fast_loop we can make speculative assumptions, and put the
4487 // conditions into the multiversion_if. If the conditions hold at runtime,
4488 // we enter the fast_loop, if the conditions fail, we take the slow_loop
4489 // instead which does not make any of the speculative assumptions.
4490 //
4491 // Note: we only multiversion the loop if the loop does not have any
4492 // auto vectorization check Predicate. If we have that predicate,
4493 // then we can simply add the speculative assumption checks to
4494 // that Predicate. This means we do not need to duplicate the
4495 // loop - we have a smaller graph and save compile time. Should
4496 // the conditions ever fail, then we deopt / trap at the Predicate
4497 // and recompile without that Predicate. At that point we will
4498 // multiversion the loop, so that we can still have speculative
4499 // runtime checks.
4500 //
4501 // We perform the multiversioning when the loop is still in its single
4502 // iteration form, even before we insert pre and post loops. This makes
4503 // the cloning much simpler. However, this means that both the fast
4504 // and the slow loop have to be optimized independently (adding pre
4505 // and post loops, unrolling the main loop, auto-vectorize etc.). And
4506 // we may end up not needing any speculative assumptions in the fast_loop
4507 // and then rejecting the slow_loop by constant folding the multiversion_if.
4508 //
4509 // Therefore, we "delay" the optimization of the slow_loop until we add
4510 // at least one speculative assumption for the fast_loop. If we never
4511 // add such a speculative runtime check, the OpaqueMultiversioningNode
4512 // of the multiversion_if constant folds to true after loop opts, and the
4513 // multiversion_if folds away the "delayed" slow_loop. If we add any
4514 // speculative assumption, then we notify the OpaqueMultiversioningNode
4515 // with "notify_slow_loop_that_it_can_resume_optimizations".
4516 //
4517 // Note: new runtime checks can be added to the multiversion_if with
4518 // PhaseIdealLoop::create_new_if_for_multiversion
4519 void PhaseIdealLoop::maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new) {
4520 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4521 LoopNode* outer_loop = cl->skip_strip_mined();
4522 Node* entry = outer_loop->in(LoopNode::EntryControl);
4523
4524 // Check we have multiversioning enabled, and are not already multiversioned.
4525 if (!LoopMultiversioning || cl->is_multiversion()) { return; }
4526
4527 // Check that we do not have a parse-predicate where we can add the runtime checks
4528 // during auto-vectorization.
4529 const Predicates predicates(entry);
4530 const PredicateBlock* predicate_block = predicates.auto_vectorization_check_block();
4531 if (predicate_block->has_parse_predicate()) { return; }
4532
4533 // Check node budget.
4534 uint estimate = lpt->est_loop_clone_sz(2);
4535 if (!may_require_nodes(estimate)) { return; }
4536
4537 do_multiversioning(lpt, old_new);
4538 }
4539
4540 // Returns true if the Reduction node is unordered.
4541 static bool is_unordered_reduction(Node* n) {
4542 return n->is_Reduction() && !n->as_Reduction()->requires_strict_order();
4543 }
4544
4545 // Having ReductionNodes in the loop is expensive. They need to recursively
4546 // fold together the vector values, for every vectorized loop iteration. If
4547 // we encounter the following pattern, we can vector accumulate the values
4548 // inside the loop, and only have a single UnorderedReduction after the loop.
4549 //
4550 // Note: UnorderedReduction represents a ReductionNode which does not require
4551 // calculating in strict order.
4552 //
4553 // CountedLoop init
4554 // | |
4555 // +------+ | +-----------------------+
4556 // | | | |
4557 // PhiNode (s) |
4558 // | |
4559 // | Vector |
4560 // | | |
4561 // UnorderedReduction (first_ur) |
4562 // | |
4563 // ... Vector |
4564 // | | |
4565 // UnorderedReduction (last_ur) |
4566 // | |
4567 // +---------------------+
4568 //
4569 // We patch the graph to look like this:
4570 //
4571 // CountedLoop identity_vector
4572 // | |
4573 // +-------+ | +---------------+
4574 // | | | |
4575 // PhiNode (v) |
4576 // | |
4577 // | Vector |
4578 // | | |
4579 // VectorAccumulator |
4580 // | |
4581 // ... Vector |
4582 // | | |
4583 // init VectorAccumulator |
4584 // | | | |
4585 // UnorderedReduction +-----------+
4586 //
4587 // We turned the scalar (s) Phi into a vectorized one (v). In the loop, we
4588 // use vector_accumulators, which do the same reductions, but only element
4589 // wise. This is a single operation per vector_accumulator, rather than many
4590 // for a UnorderedReduction. We can then reduce the last vector_accumulator
4591 // after the loop, and also reduce the init value into it.
4592 //
4593 // We can not do this with all reductions. Some reductions do not allow the
4594 // reordering of operations (for example float addition/multiplication require
4595 // strict order).
4596 void PhaseIdealLoop::move_unordered_reduction_out_of_loop(IdealLoopTree* loop) {
4597 assert(!C->major_progress() && loop->is_counted() && loop->is_innermost(), "sanity");
4598
4599 // Find all Phi nodes with an unordered Reduction on backedge.
4600 CountedLoopNode* cl = loop->_head->as_CountedLoop();
4601 for (DUIterator_Fast jmax, j = cl->fast_outs(jmax); j < jmax; j++) {
4602 Node* phi = cl->fast_out(j);
4603 // We have a phi with a single use, and an unordered Reduction on the backedge.
4604 if (!phi->is_Phi() || phi->outcnt() != 1 || !is_unordered_reduction(phi->in(2))) {
4605 continue;
4606 }
4607
4608 ReductionNode* last_ur = phi->in(2)->as_Reduction();
4609 assert(!last_ur->requires_strict_order(), "must be");
4610
4611 // Determine types
4612 const TypeVect* vec_t = last_ur->vect_type();
4613 uint vector_length = vec_t->length();
4614 BasicType bt = vec_t->element_basic_type();
4615
4616 // Convert opcode from vector-reduction -> scalar -> normal-vector-op
4617 const int sopc = VectorNode::scalar_opcode(last_ur->Opcode(), bt);
4618 const int vopc = VectorNode::opcode(sopc, bt);
4619 if (!Matcher::match_rule_supported_vector(vopc, vector_length, bt)) {
4620 DEBUG_ONLY( last_ur->dump(); )
4621 assert(false, "do not have normal vector op for this reduction");
4622 continue; // not implemented -> fails
4623 }
4624
4625 // Traverse up the chain of unordered Reductions, checking that it loops back to
4626 // the phi. Check that all unordered Reductions only have a single use, except for
4627 // the last (last_ur), which only has phi as a use in the loop, and all other uses
4628 // are outside the loop.
4629 ReductionNode* current = last_ur;
4630 ReductionNode* first_ur = nullptr;
4631 while (true) {
4632 assert(!current->requires_strict_order(), "sanity");
4633
4634 // Expect no ctrl and a vector_input from within the loop.
4635 Node* ctrl = current->in(0);
4636 Node* vector_input = current->in(2);
4637 if (ctrl != nullptr || get_ctrl(vector_input) != cl) {
4638 DEBUG_ONLY( current->dump(1); )
4639 assert(false, "reduction has ctrl or bad vector_input");
4640 break; // Chain traversal fails.
4641 }
4642
4643 assert(current->vect_type() != nullptr, "must have vector type");
4644 if (current->vect_type() != last_ur->vect_type()) {
4645 // Reductions do not have the same vector type (length and element type).
4646 break; // Chain traversal fails.
4647 }
4648
4649 // Expect single use of an unordered Reduction, except for last_ur.
4650 if (current == last_ur) {
4651 // Expect all uses to be outside the loop, except phi.
4652 for (DUIterator_Fast kmax, k = current->fast_outs(kmax); k < kmax; k++) {
4653 Node* use = current->fast_out(k);
4654 if (use != phi && ctrl_or_self(use) == cl) {
4655 DEBUG_ONLY( current->dump(-1); )
4656 assert(false, "reduction has use inside loop");
4657 // Should not be allowed by SuperWord::mark_reductions
4658 return; // bail out of optimization
4659 }
4660 }
4661 } else {
4662 if (current->outcnt() != 1) {
4663 break; // Chain traversal fails.
4664 }
4665 }
4666
4667 // Expect another unordered Reduction or phi as the scalar input.
4668 Node* scalar_input = current->in(1);
4669 if (is_unordered_reduction(scalar_input) &&
4670 scalar_input->Opcode() == current->Opcode()) {
4671 // Move up the unordered Reduction chain.
4672 current = scalar_input->as_Reduction();
4673 assert(!current->requires_strict_order(), "must be");
4674 } else if (scalar_input == phi) {
4675 // Chain terminates at phi.
4676 first_ur = current;
4677 current = nullptr;
4678 break; // Success.
4679 } else {
4680 // scalar_input is neither phi nor a matching reduction
4681 // Can for example be scalar reduction when we have
4682 // partial vectorization.
4683 break; // Chain traversal fails.
4684 }
4685 }
4686 if (current != nullptr) {
4687 // Chain traversal was not successful.
4688 continue;
4689 }
4690 assert(first_ur != nullptr, "must have successfully terminated chain traversal");
4691
4692 Node* identity_scalar = ReductionNode::make_identity_con_scalar(_igvn, sopc, bt);
4693 set_root_as_ctrl(identity_scalar);
4694 VectorNode* identity_vector = VectorNode::scalar2vector(identity_scalar, vector_length, bt);
4695 register_new_node(identity_vector, C->root());
4696 assert(vec_t == identity_vector->vect_type(), "matching vector type");
4697 VectorNode::trace_new_vector(identity_vector, "Unordered Reduction");
4698
4699 // Turn the scalar phi into a vector phi.
4700 _igvn.rehash_node_delayed(phi);
4701 Node* init = phi->in(1); // Remember init before replacing it.
4702 phi->set_req_X(1, identity_vector, &_igvn);
4703 phi->as_Type()->set_type(vec_t);
4704 _igvn.set_type(phi, vec_t);
4705
4706 // Traverse down the chain of unordered Reductions, and replace them with vector_accumulators.
4707 current = first_ur;
4708 while (true) {
4709 // Create vector_accumulator to replace current.
4710 Node* last_vector_accumulator = current->in(1);
4711 Node* vector_input = current->in(2);
4712 VectorNode* vector_accumulator = VectorNode::make(vopc, last_vector_accumulator, vector_input, vec_t);
4713 register_new_node(vector_accumulator, cl);
4714 _igvn.replace_node(current, vector_accumulator);
4715 VectorNode::trace_new_vector(vector_accumulator, "Unordered Reduction");
4716 if (current == last_ur) {
4717 break;
4718 }
4719 current = vector_accumulator->unique_out()->as_Reduction();
4720 assert(!current->requires_strict_order(), "must be");
4721 }
4722
4723 // Create post-loop reduction.
4724 Node* last_accumulator = phi->in(2);
4725 Node* post_loop_reduction = ReductionNode::make(sopc, nullptr, init, last_accumulator, bt);
4726
4727 // Take over uses of last_accumulator that are not in the loop.
4728 for (DUIterator i = last_accumulator->outs(); last_accumulator->has_out(i); i++) {
4729 Node* use = last_accumulator->out(i);
4730 if (use != phi && use != post_loop_reduction) {
4731 assert(ctrl_or_self(use) != cl, "use must be outside loop");
4732 use->replace_edge(last_accumulator, post_loop_reduction, &_igvn);
4733 --i;
4734 }
4735 }
4736 register_new_node(post_loop_reduction, get_late_ctrl(post_loop_reduction, cl));
4737 VectorNode::trace_new_vector(post_loop_reduction, "Unordered Reduction");
4738
4739 assert(last_accumulator->outcnt() == 2, "last_accumulator has 2 uses: phi and post_loop_reduction");
4740 assert(post_loop_reduction->outcnt() > 0, "should have taken over all non loop uses of last_accumulator");
4741 assert(phi->outcnt() == 1, "accumulator is the only use of phi");
4742 }
4743 }
4744
4745 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4746 for (uint i = 0; i < _data_nodes.size(); i++) {
4747 clone(_data_nodes[i], new_ctrl);
4748 }
4749 }
4750
4751 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4752 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4753 Node* clone = node->clone();
4754 _phase->igvn().register_new_node_with_optimizer(clone);
4755 _orig_to_new.put(node, clone);
4756 _phase->set_ctrl(clone, new_ctrl);
4757 if (node->is_CastII()) {
4758 clone->set_req(0, new_ctrl);
4759 }
4760 }
4761
4762 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4763 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4764 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4765 _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4766 for (uint i = 1; i < node->req(); i++) {
4767 Node** cloned_input = _orig_to_new.get(node->in(i));
4768 if (cloned_input != nullptr) {
4769 // Input was also cloned -> rewire clone to the cloned input.
4770 _phase->igvn().replace_input_of(clone, i, *cloned_input);
4771 }
4772 }
4773 });
4774 }
4775
4776 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4777 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4778 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4779 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4780 Node* new_ctrl) {
4781 for (uint i = 0; i < _data_nodes.size(); i++) {
4782 Node* data_node = _data_nodes[i];
4783 if (data_node->is_Opaque1()) {
4784 transform_opaque_node(transform_strategy, data_node);
4785 } else {
4786 clone(data_node, new_ctrl);
4787 }
4788 }
4789 }
4790
4791 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4792 Node* transformed_node;
4793 if (node->is_OpaqueLoopInit()) {
4794 transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4795 } else {
4796 assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4797 transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4798 }
4799 // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4800 _orig_to_new.put(node, transformed_node);
4801 }