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,
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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/castnode.hpp"
34 #include "opto/divnode.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/mulnode.hpp"
38 #include "opto/movenode.hpp"
39 #include "opto/opaquenode.hpp"
40 #include "opto/rootnode.hpp"
41 #include "opto/subnode.hpp"
42 #include "opto/subtypenode.hpp"
43 #include "opto/superword.hpp"
44 #include "opto/vectornode.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 int wins = 0;
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++;
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++;
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++;
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 = 0;
170 break;
171 }
172 }
173 // Too few wins?
174 if (wins <= 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 return phi;
232 }
233
234 // Test whether node 'x' can move into an inner loop relative to node 'n'.
235 // Note: The test is not exact. Returns true if 'x' COULD end up in an inner loop,
236 // BUT it can also return true and 'x' is in the outer loop
237 bool PhaseIdealLoop::can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x) {
238 IdealLoopTree* n_loop_tree = get_loop(n_loop);
239 IdealLoopTree* x_loop_tree = get_loop(get_early_ctrl(x));
240 // x_loop_tree should be outer or same loop as n_loop_tree
241 return !x_loop_tree->is_member(n_loop_tree);
242 }
243
244 // Subtype checks that carry profile data don't common so look for a replacement by following edges
245 Node* PhaseIdealLoop::similar_subtype_check(const Node* x, Node* r_in) {
246 if (x->is_SubTypeCheck()) {
247 Node* in1 = x->in(1);
248 for (DUIterator_Fast imax, i = in1->fast_outs(imax); i < imax; i++) {
249 Node* u = in1->fast_out(i);
250 if (u != x && u->is_SubTypeCheck() && u->in(1) == x->in(1) && u->in(2) == x->in(2)) {
251 for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
252 Node* bol = u->fast_out(j);
253 for (DUIterator_Fast kmax, k = bol->fast_outs(kmax); k < kmax; k++) {
254 Node* iff = bol->fast_out(k);
255 // Only dominating subtype checks are interesting: otherwise we risk replacing a subtype check by another with
256 // unrelated profile
257 if (iff->is_If() && is_dominator(iff, r_in)) {
258 return u;
259 }
260 }
261 }
262 }
263 }
264 }
265 return nullptr;
266 }
267
268 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
269 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
270 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
271 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
272 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
273 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
274 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
275 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
276 const Type* zero;
277 switch (n->Opcode()) {
278 case Op_DivI:
279 case Op_ModI:
280 case Op_UDivI:
281 case Op_UModI:
282 zero = TypeInt::ZERO;
283 break;
284 case Op_DivL:
285 case Op_ModL:
286 case Op_UDivL:
287 case Op_UModL:
288 zero = TypeLong::ZERO;
289 break;
290 default:
291 return false;
292 }
293
294 if (n->in(0) != nullptr) {
295 // Cannot split through phi if Div or Mod node has a control dependency to a zero check.
296 return true;
297 }
298
299 Node* divisor = n->in(2);
300 return is_divisor_loop_phi(divisor, region) &&
301 loop_phi_backedge_type_contains_zero(divisor, zero);
302 }
303
304 bool PhaseIdealLoop::is_divisor_loop_phi(const Node* divisor, const Node* loop) {
305 return loop->is_Loop() && divisor->is_Phi() && divisor->in(0) == loop;
306 }
307
308 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
309 return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
310 }
311
312 //------------------------------dominated_by------------------------------------
313 // Replace the dominated test with an obvious true or false. Place it on the
314 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
315 // live path up to the dominating control.
316 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool pin_array_access_nodes) {
317 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
318
319 // prevdom is the dominating projection of the dominating test.
320 assert(iff->Opcode() == Op_If ||
321 iff->Opcode() == Op_CountedLoopEnd ||
322 iff->Opcode() == Op_LongCountedLoopEnd ||
323 iff->Opcode() == Op_RangeCheck ||
324 iff->Opcode() == Op_ParsePredicate,
325 "Check this code when new subtype is added");
326
327 int pop = prevdom->Opcode();
328 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
329 if (flip) {
330 if (pop == Op_IfTrue)
331 pop = Op_IfFalse;
332 else
333 pop = Op_IfTrue;
334 }
335 // 'con' is set to true or false to kill the dominated test.
336 Node* con = makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
337 // Hack the dominated test
338 _igvn.replace_input_of(iff, 1, con);
339
340 // If I don't have a reachable TRUE and FALSE path following the IfNode then
341 // I can assume this path reaches an infinite loop. In this case it's not
342 // important to optimize the data Nodes - either the whole compilation will
343 // be tossed or this path (and all data Nodes) will go dead.
344 if (iff->outcnt() != 2) {
345 return;
346 }
347
348 // Make control-dependent data Nodes on the live path (path that will remain
349 // once the dominated IF is removed) become control-dependent on the
350 // dominating projection.
351 Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
352
353 if (dp == nullptr) {
354 return;
355 }
356
357 rewire_safe_outputs_to_dominator(dp, prevdom, pin_array_access_nodes);
358 }
359
360 void PhaseIdealLoop::rewire_safe_outputs_to_dominator(Node* source, Node* dominator, const bool pin_array_access_nodes) {
361 IdealLoopTree* old_loop = get_loop(source);
362
363 for (DUIterator_Fast imax, i = source->fast_outs(imax); i < imax; i++) {
364 Node* out = source->fast_out(i); // Control-dependent node
365 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
366 if (out->depends_only_on_test() && _igvn.no_dependent_zero_check(out)) {
367 assert(out->in(0) == source, "must be control dependent on source");
368 _igvn.replace_input_of(out, 0, dominator);
369 if (pin_array_access_nodes) {
370 // Because of Loop Predication, Loads and range check Cast nodes that are control dependent on this range
371 // check (that is about to be removed) now depend on multiple dominating Hoisted Check Predicates. After the
372 // removal of this range check, these control dependent nodes end up at the lowest/nearest dominating predicate
373 // in the graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
374 // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the lowest
375 // dominating check.
376 Node* clone = out->pin_array_access_node();
377 if (clone != nullptr) {
378 clone = _igvn.register_new_node_with_optimizer(clone, out);
379 _igvn.replace_node(out, clone);
380 out = clone;
381 }
382 }
383 set_early_ctrl(out, false);
384 IdealLoopTree* new_loop = get_loop(get_ctrl(out));
385 if (old_loop != new_loop) {
386 if (!old_loop->_child) {
387 old_loop->_body.yank(out);
388 }
389 if (!new_loop->_child) {
390 new_loop->_body.push(out);
391 }
392 }
393 --i;
394 --imax;
395 }
396 }
397 }
398
399 //------------------------------has_local_phi_input----------------------------
400 // Return TRUE if 'n' has Phi inputs from its local block and no other
401 // block-local inputs (all non-local-phi inputs come from earlier blocks)
402 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
403 Node *n_ctrl = get_ctrl(n);
404 // See if some inputs come from a Phi in this block, or from before
405 // this block.
406 uint i;
407 for( i = 1; i < n->req(); i++ ) {
408 Node *phi = n->in(i);
409 if( phi->is_Phi() && phi->in(0) == n_ctrl )
410 break;
411 }
412 if( i >= n->req() )
413 return nullptr; // No Phi inputs; nowhere to clone thru
414
415 // Check for inputs created between 'n' and the Phi input. These
416 // must split as well; they have already been given the chance
417 // (courtesy of a post-order visit) and since they did not we must
418 // recover the 'cost' of splitting them by being very profitable
419 // when splitting 'n'. Since this is unlikely we simply give up.
420 for( i = 1; i < n->req(); i++ ) {
421 Node *m = n->in(i);
422 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
423 // We allow the special case of AddP's with no local inputs.
424 // This allows us to split-up address expressions.
425 if (m->is_AddP() &&
426 get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
427 get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
428 get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
429 // Move the AddP up to the dominating point. That's fine because control of m's inputs
430 // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
431 Node* c = find_non_split_ctrl(idom(n_ctrl));
432 if (c->is_OuterStripMinedLoop()) {
433 c->as_Loop()->verify_strip_mined(1);
434 c = c->in(LoopNode::EntryControl);
435 }
436 set_ctrl_and_loop(m, c);
437 continue;
438 }
439 return nullptr;
440 }
441 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
442 }
443
444 return n_ctrl;
445 }
446
447 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
448 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
449 assert(bt == T_INT || bt == T_LONG, "only for integers");
450 int n_op = n->Opcode();
451
452 if (n_op == Op_LShift(bt)) {
453 // Scale is loop invariant
454 Node* scale = n->in(2);
455 Node* scale_ctrl = get_ctrl(scale);
456 IdealLoopTree* scale_loop = get_loop(scale_ctrl);
457 if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
458 return nullptr;
459 }
460 const TypeInt* scale_t = scale->bottom_type()->isa_int();
461 if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
462 return nullptr; // Dont bother with byte/short masking
463 }
464 // Add must vary with loop (else shift would be loop-invariant)
465 Node* add = n->in(1);
466 Node* add_ctrl = get_ctrl(add);
467 IdealLoopTree* add_loop = get_loop(add_ctrl);
468 if (n_loop != add_loop) {
469 return nullptr; // happens w/ evil ZKM loops
470 }
471
472 // Convert I-V into I+ (0-V); same for V-I
473 if (add->Opcode() == Op_Sub(bt) &&
474 _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
475 assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
476 Node* zero = integercon(0, bt);
477 Node* neg = SubNode::make(zero, add->in(2), bt);
478 register_new_node_with_ctrl_of(neg, add->in(2));
479 add = AddNode::make(add->in(1), neg, bt);
480 register_new_node(add, add_ctrl);
481 }
482 if (add->Opcode() != Op_Add(bt)) return nullptr;
483 assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
484 // See if one add input is loop invariant
485 Node* add_var = add->in(1);
486 Node* add_var_ctrl = get_ctrl(add_var);
487 IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
488 Node* add_invar = add->in(2);
489 Node* add_invar_ctrl = get_ctrl(add_invar);
490 IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
491 if (add_invar_loop == n_loop) {
492 // Swap to find the invariant part
493 add_invar = add_var;
494 add_invar_ctrl = add_var_ctrl;
495 add_invar_loop = add_var_loop;
496 add_var = add->in(2);
497 } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
498 return nullptr;
499 }
500 if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
501 return nullptr; // No invariant part of the add?
502 }
503
504 // Yes! Reshape address expression!
505 Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
506 Node* inv_scale_ctrl =
507 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
508 add_invar_ctrl : scale_ctrl;
509 register_new_node(inv_scale, inv_scale_ctrl);
510 Node* var_scale = LShiftNode::make(add_var, scale, bt);
511 register_new_node(var_scale, n_ctrl);
512 Node* var_add = AddNode::make(var_scale, inv_scale, bt);
513 register_new_node(var_add, n_ctrl);
514 _igvn.replace_node(n, var_add);
515 return var_add;
516 }
517 return nullptr;
518 }
519
520 //------------------------------remix_address_expressions----------------------
521 // Rework addressing expressions to get the most loop-invariant stuff
522 // moved out. We'd like to do all associative operators, but it's especially
523 // important (common) to do address expressions.
524 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
525 if (!has_ctrl(n)) return nullptr;
526 Node* n_ctrl = get_ctrl(n);
527 IdealLoopTree* n_loop = get_loop(n_ctrl);
528
529 // See if 'n' mixes loop-varying and loop-invariant inputs and
530 // itself is loop-varying.
531
532 // Only interested in binary ops (and AddP)
533 if (n->req() < 3 || n->req() > 4) return nullptr;
534
535 Node* n1_ctrl = get_ctrl(n->in( 1));
536 Node* n2_ctrl = get_ctrl(n->in( 2));
537 Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
538 IdealLoopTree* n1_loop = get_loop(n1_ctrl);
539 IdealLoopTree* n2_loop = get_loop(n2_ctrl);
540 IdealLoopTree* n3_loop = get_loop(n3_ctrl);
541
542 // Does one of my inputs spin in a tighter loop than self?
543 if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
544 (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
545 (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
546 return nullptr; // Leave well enough alone
547 }
548
549 // Is at least one of my inputs loop-invariant?
550 if (n1_loop == n_loop &&
551 n2_loop == n_loop &&
552 n3_loop == n_loop) {
553 return nullptr; // No loop-invariant inputs
554 }
555
556 Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
557 if (res != nullptr) {
558 return res;
559 }
560 res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
561 if (res != nullptr) {
562 return res;
563 }
564
565 int n_op = n->Opcode();
566 // Replace (I+V) with (V+I)
567 if (n_op == Op_AddI ||
568 n_op == Op_AddL ||
569 n_op == Op_AddF ||
570 n_op == Op_AddD ||
571 n_op == Op_MulI ||
572 n_op == Op_MulL ||
573 n_op == Op_MulF ||
574 n_op == Op_MulD) {
575 if (n2_loop == n_loop) {
576 assert(n1_loop != n_loop, "");
577 n->swap_edges(1, 2);
578 }
579 }
580
581 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
582 // but not if I2 is a constant. Skip for irreducible loops.
583 if (n_op == Op_AddP && n_loop->_head->is_Loop()) {
584 if (n2_loop == n_loop && n3_loop != n_loop) {
585 if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
586 Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
587 Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
588 IdealLoopTree* n22loop = get_loop(n22_ctrl);
589 IdealLoopTree* n23_loop = get_loop(n23_ctrl);
590 if (n22loop != n_loop && n22loop->is_member(n_loop) &&
591 n23_loop == n_loop) {
592 Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
593 // Stuff new AddP in the loop preheader
594 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
595 Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
596 register_new_node(add2, n_ctrl);
597 _igvn.replace_node(n, add2);
598 return add2;
599 }
600 }
601 }
602
603 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
604 if (n2_loop != n_loop && n3_loop == n_loop) {
605 if (n->in(3)->Opcode() == Op_AddX) {
606 Node* V = n->in(3)->in(1);
607 Node* I = n->in(3)->in(2);
608 if (is_member(n_loop,get_ctrl(V))) {
609 } else {
610 Node *tmp = V; V = I; I = tmp;
611 }
612 if (!is_member(n_loop,get_ctrl(I))) {
613 Node* add1 = new AddPNode(n->in(1), n->in(2), I);
614 // Stuff new AddP in the loop preheader
615 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
616 Node* add2 = new AddPNode(n->in(1), add1, V);
617 register_new_node(add2, n_ctrl);
618 _igvn.replace_node(n, add2);
619 return add2;
620 }
621 }
622 }
623 }
624
625 return nullptr;
626 }
627
628 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
629 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
630 assert(n->Opcode() == Op_AddI, "sanity");
631 Node * nn = nullptr;
632 Node * in1 = n->in(1);
633 Node * in2 = n->in(2);
634 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
635 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
636 if (loop_n->is_counted() &&
637 loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
638 Matcher::match_rule_supported(Op_MulAddVS2VI) &&
639 Matcher::match_rule_supported(Op_MulAddS2I)) {
640 Node* mul_in1 = in1->in(1);
641 Node* mul_in2 = in1->in(2);
642 Node* mul_in3 = in2->in(1);
643 Node* mul_in4 = in2->in(2);
644 if (mul_in1->Opcode() == Op_LoadS &&
645 mul_in2->Opcode() == Op_LoadS &&
646 mul_in3->Opcode() == Op_LoadS &&
647 mul_in4->Opcode() == Op_LoadS) {
648 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
649 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
650 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
651 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
652 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
653 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
654 // All nodes should be in the same counted loop.
655 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
656 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
657 Node* adr1 = mul_in1->in(MemNode::Address);
658 Node* adr2 = mul_in2->in(MemNode::Address);
659 Node* adr3 = mul_in3->in(MemNode::Address);
660 Node* adr4 = mul_in4->in(MemNode::Address);
661 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
662 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
663 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
664 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
665 register_new_node_with_ctrl_of(nn, n);
666 _igvn.replace_node(n, nn);
667 return nn;
668 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
669 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
670 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
671 register_new_node_with_ctrl_of(nn, n);
672 _igvn.replace_node(n, nn);
673 return nn;
674 }
675 }
676 }
677 }
678 }
679 }
680 return nn;
681 }
682
683 //------------------------------conditional_move-------------------------------
684 // Attempt to replace a Phi with a conditional move. We have some pretty
685 // strict profitability requirements. All Phis at the merge point must
686 // be converted, so we can remove the control flow. We need to limit the
687 // number of c-moves to a small handful. All code that was in the side-arms
688 // of the CFG diamond is now speculatively executed. This code has to be
689 // "cheap enough". We are pretty much limited to CFG diamonds that merge
690 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
691 Node *PhaseIdealLoop::conditional_move( Node *region ) {
692
693 assert(region->is_Region(), "sanity check");
694 if (region->req() != 3) return nullptr;
695
696 // Check for CFG diamond
697 Node *lp = region->in(1);
698 Node *rp = region->in(2);
699 if (!lp || !rp) return nullptr;
700 Node *lp_c = lp->in(0);
701 if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
702 IfNode *iff = lp_c->as_If();
703
704 // Check for ops pinned in an arm of the diamond.
705 // Can't remove the control flow in this case
706 if (lp->outcnt() > 1) return nullptr;
707 if (rp->outcnt() > 1) return nullptr;
708
709 IdealLoopTree* r_loop = get_loop(region);
710 assert(r_loop == get_loop(iff), "sanity");
711 // Always convert to CMOVE if all results are used only outside this loop.
712 bool used_inside_loop = (r_loop == _ltree_root);
713
714 // Check profitability
715 int cost = 0;
716 int phis = 0;
717 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
718 Node *out = region->fast_out(i);
719 if (!out->is_Phi()) continue; // Ignore other control edges, etc
720 phis++;
721 PhiNode* phi = out->as_Phi();
722 BasicType bt = phi->type()->basic_type();
723 switch (bt) {
724 case T_DOUBLE:
725 case T_FLOAT:
726 if (C->use_cmove()) {
727 continue; //TODO: maybe we want to add some cost
728 }
729 cost += Matcher::float_cmove_cost(); // Could be very expensive
730 break;
731 case T_LONG: {
732 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
733 }
734 case T_INT: // These all CMOV fine
735 case T_ADDRESS: { // (RawPtr)
736 cost++;
737 break;
738 }
739 case T_NARROWOOP: // Fall through
740 case T_OBJECT: { // Base oops are OK, but not derived oops
741 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
742 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
743 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
744 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
745 // have a Phi for the base here that we convert to a CMOVE all is well
746 // and good. But if the base is dead, we'll not make a CMOVE. Later
747 // the allocator will have to produce a base by creating a CMOVE of the
748 // relevant bases. This puts the allocator in the business of
749 // manufacturing expensive instructions, generally a bad plan.
750 // Just Say No to Conditionally-Moved Derived Pointers.
751 if (tp && tp->offset() != 0)
752 return nullptr;
753 cost++;
754 break;
755 }
756 default:
757 return nullptr; // In particular, can't do memory or I/O
758 }
759 // Add in cost any speculative ops
760 for (uint j = 1; j < region->req(); j++) {
761 Node *proj = region->in(j);
762 Node *inp = phi->in(j);
763 if (get_ctrl(inp) == proj) { // Found local op
764 cost++;
765 // Check for a chain of dependent ops; these will all become
766 // speculative in a CMOV.
767 for (uint k = 1; k < inp->req(); k++)
768 if (get_ctrl(inp->in(k)) == proj)
769 cost += ConditionalMoveLimit; // Too much speculative goo
770 }
771 }
772 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
773 // This will likely Split-If, a higher-payoff operation.
774 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
775 Node* use = phi->fast_out(k);
776 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
777 cost += ConditionalMoveLimit;
778 // Is there a use inside the loop?
779 // Note: check only basic types since CMoveP is pinned.
780 if (!used_inside_loop && is_java_primitive(bt)) {
781 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
782 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
783 used_inside_loop = true;
784 }
785 }
786 }
787 }//for
788 Node* bol = iff->in(1);
789 assert(!bol->is_OpaqueInitializedAssertionPredicate(), "Initialized Assertion Predicates cannot form a diamond with Halt");
790 if (bol->is_OpaqueTemplateAssertionPredicate()) {
791 // Ignore Template Assertion Predicates with OpaqueTemplateAssertionPredicate nodes.
792 return nullptr;
793 }
794 assert(bol->Opcode() == Op_Bool, "Unexpected node");
795 int cmp_op = bol->in(1)->Opcode();
796 if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
797 return nullptr;
798 }
799 // It is expensive to generate flags from a float compare.
800 // Avoid duplicated float compare.
801 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
802
803 float infrequent_prob = PROB_UNLIKELY_MAG(3);
804 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
805 if (used_inside_loop) {
806 if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
807
808 // BlockLayoutByFrequency optimization moves infrequent branch
809 // from hot path. No point in CMOV'ing in such case (110 is used
810 // instead of 100 to take into account not exactness of float value).
811 if (BlockLayoutByFrequency) {
812 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
813 }
814 }
815 // Check for highly predictable branch. No point in CMOV'ing if
816 // we are going to predict accurately all the time.
817 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
818 //keep going
819 } else if (iff->_prob < infrequent_prob ||
820 iff->_prob > (1.0f - infrequent_prob))
821 return nullptr;
822
823 // --------------
824 // Now replace all Phis with CMOV's
825 Node *cmov_ctrl = iff->in(0);
826 uint flip = (lp->Opcode() == Op_IfTrue);
827 Node_List wq;
828 while (1) {
829 PhiNode* phi = nullptr;
830 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
831 Node *out = region->fast_out(i);
832 if (out->is_Phi()) {
833 phi = out->as_Phi();
834 break;
835 }
836 }
837 if (phi == nullptr || _igvn.type(phi) == Type::TOP) {
838 break;
839 }
840 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
841 // Move speculative ops
842 wq.push(phi);
843 while (wq.size() > 0) {
844 Node *n = wq.pop();
845 for (uint j = 1; j < n->req(); j++) {
846 Node* m = n->in(j);
847 if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
848 #ifndef PRODUCT
849 if (PrintOpto && VerifyLoopOptimizations) {
850 tty->print(" speculate: ");
851 m->dump();
852 }
853 #endif
854 set_ctrl(m, cmov_ctrl);
855 wq.push(m);
856 }
857 }
858 }
859 Node* cmov = CMoveNode::make(iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
860 register_new_node(cmov, cmov_ctrl);
861 _igvn.replace_node(phi, cmov);
862 #ifndef PRODUCT
863 if (TraceLoopOpts) {
864 tty->print("CMOV ");
865 r_loop->dump_head();
866 if (Verbose) {
867 bol->in(1)->dump(1);
868 cmov->dump(1);
869 }
870 }
871 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
872 #endif
873 }
874
875 // The useless CFG diamond will fold up later; see the optimization in
876 // RegionNode::Ideal.
877 _igvn._worklist.push(region);
878
879 return iff->in(1);
880 }
881
882 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
883 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
884 Node* u = m->fast_out(i);
885 if (u->is_CFG()) {
886 if (u->is_NeverBranch()) {
887 u = u->as_NeverBranch()->proj_out(0);
888 enqueue_cfg_uses(u, wq);
889 } else {
890 wq.push(u);
891 }
892 }
893 }
894 }
895
896 // Try moving a store out of a loop, right before the loop
897 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
898 // Store has to be first in the loop body
899 IdealLoopTree *n_loop = get_loop(n_ctrl);
900 if (n->is_Store() && n_loop != _ltree_root &&
901 n_loop->is_loop() && n_loop->_head->is_Loop() &&
902 n->in(0) != nullptr) {
903 Node* address = n->in(MemNode::Address);
904 Node* value = n->in(MemNode::ValueIn);
905 Node* mem = n->in(MemNode::Memory);
906 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
907 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
908
909 // - address and value must be loop invariant
910 // - memory must be a memory Phi for the loop
911 // - Store must be the only store on this memory slice in the
912 // loop: if there's another store following this one then value
913 // written at iteration i by the second store could be overwritten
914 // at iteration i+n by the first store: it's not safe to move the
915 // first store out of the loop
916 // - nothing must observe the memory Phi: it guarantees no read
917 // before the store, we are also guaranteed the store post
918 // dominates the loop head (ignoring a possible early
919 // exit). Otherwise there would be extra Phi involved between the
920 // loop's Phi and the store.
921 // - there must be no early exit from the loop before the Store
922 // (such an exit most of the time would be an extra use of the
923 // memory Phi but sometimes is a bottom memory Phi that takes the
924 // store as input).
925
926 if (!n_loop->is_member(address_loop) &&
927 !n_loop->is_member(value_loop) &&
928 mem->is_Phi() && mem->in(0) == n_loop->_head &&
929 mem->outcnt() == 1 &&
930 mem->in(LoopNode::LoopBackControl) == n) {
931
932 assert(n_loop->_tail != nullptr, "need a tail");
933 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
934
935 // Verify that there's no early exit of the loop before the store.
936 bool ctrl_ok = false;
937 {
938 // Follow control from loop head until n, we exit the loop or
939 // we reach the tail
940 ResourceMark rm;
941 Unique_Node_List wq;
942 wq.push(n_loop->_head);
943
944 for (uint next = 0; next < wq.size(); ++next) {
945 Node *m = wq.at(next);
946 if (m == n->in(0)) {
947 ctrl_ok = true;
948 continue;
949 }
950 assert(!has_ctrl(m), "should be CFG");
951 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
952 ctrl_ok = false;
953 break;
954 }
955 enqueue_cfg_uses(m, wq);
956 if (wq.size() > 10) {
957 ctrl_ok = false;
958 break;
959 }
960 }
961 }
962 if (ctrl_ok) {
963 // move the Store
964 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
965 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
966 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
967 // Disconnect the phi now. An empty phi can confuse other
968 // optimizations in this pass of loop opts.
969 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
970 n_loop->_body.yank(mem);
971
972 set_ctrl_and_loop(n, n->in(0));
973
974 return n;
975 }
976 }
977 }
978 return nullptr;
979 }
980
981 // Try moving a store out of a loop, right after the loop
982 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
983 if (n->is_Store() && n->in(0) != nullptr) {
984 Node *n_ctrl = get_ctrl(n);
985 IdealLoopTree *n_loop = get_loop(n_ctrl);
986 // Store must be in a loop
987 if (n_loop != _ltree_root && !n_loop->_irreducible) {
988 Node* address = n->in(MemNode::Address);
989 Node* value = n->in(MemNode::ValueIn);
990 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
991 // address must be loop invariant
992 if (!n_loop->is_member(address_loop)) {
993 // Store must be last on this memory slice in the loop and
994 // nothing in the loop must observe it
995 Node* phi = nullptr;
996 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
997 Node* u = n->fast_out(i);
998 if (has_ctrl(u)) { // control use?
999 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1000 if (!n_loop->is_member(u_loop)) {
1001 continue;
1002 }
1003 if (u->is_Phi() && u->in(0) == n_loop->_head) {
1004 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1005 // multiple phis on the same slice are possible
1006 if (phi != nullptr) {
1007 return;
1008 }
1009 phi = u;
1010 continue;
1011 }
1012 }
1013 return;
1014 }
1015 if (phi != nullptr) {
1016 // Nothing in the loop before the store (next iteration)
1017 // must observe the stored value
1018 bool mem_ok = true;
1019 {
1020 ResourceMark rm;
1021 Unique_Node_List wq;
1022 wq.push(phi);
1023 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1024 Node *m = wq.at(next);
1025 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1026 Node* u = m->fast_out(i);
1027 if (u->is_Store() || u->is_Phi()) {
1028 if (u != n) {
1029 wq.push(u);
1030 mem_ok = (wq.size() <= 10);
1031 }
1032 } else {
1033 mem_ok = false;
1034 break;
1035 }
1036 }
1037 }
1038 }
1039 if (mem_ok) {
1040 // Move the store out of the loop if the LCA of all
1041 // users (except for the phi) is outside the loop.
1042 Node* hook = new Node(1);
1043 hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1044 _igvn.rehash_node_delayed(phi);
1045 int count = phi->replace_edge(n, hook, &_igvn);
1046 assert(count > 0, "inconsistent phi");
1047
1048 // Compute latest point this store can go
1049 Node* lca = get_late_ctrl(n, get_ctrl(n));
1050 if (lca->is_OuterStripMinedLoop()) {
1051 lca = lca->in(LoopNode::EntryControl);
1052 }
1053 if (n_loop->is_member(get_loop(lca))) {
1054 // LCA is in the loop - bail out
1055 _igvn.replace_node(hook, n);
1056 return;
1057 }
1058 #ifdef ASSERT
1059 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1060 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1061 n_loop->_head->as_Loop()->verify_strip_mined(1);
1062 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1063 IdealLoopTree* outer_loop = get_loop(outer);
1064 assert(n_loop->_parent == outer_loop, "broken loop tree");
1065 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1066 }
1067 #endif
1068 lca = place_outside_loop(lca, n_loop);
1069 assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1070 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");
1071
1072 // Move store out of the loop
1073 _igvn.replace_node(hook, n->in(MemNode::Memory));
1074 _igvn.replace_input_of(n, 0, lca);
1075 set_ctrl_and_loop(n, lca);
1076
1077 // Disconnect the phi now. An empty phi can confuse other
1078 // optimizations in this pass of loop opts..
1079 if (phi->in(LoopNode::LoopBackControl) == phi) {
1080 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1081 n_loop->_body.yank(phi);
1082 }
1083 }
1084 }
1085 }
1086 }
1087 }
1088 }
1089
1090 // Split some nodes that take a counted loop phi as input at a counted
1091 // loop can cause vectorization of some expressions to fail
1092 bool PhaseIdealLoop::split_thru_phi_could_prevent_vectorization(Node* n, Node* n_blk) {
1093 if (!n_blk->is_CountedLoop()) {
1094 return false;
1095 }
1096
1097 int opcode = n->Opcode();
1098
1099 if (opcode != Op_AndI &&
1100 opcode != Op_MulI &&
1101 opcode != Op_RotateRight &&
1102 opcode != Op_RShiftI) {
1103 return false;
1104 }
1105
1106 return n->in(1) == n_blk->as_BaseCountedLoop()->phi();
1107 }
1108
1109 //------------------------------split_if_with_blocks_pre-----------------------
1110 // Do the real work in a non-recursive function. Data nodes want to be
1111 // cloned in the pre-order so they can feed each other nicely.
1112 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1113 // Cloning these guys is unlikely to win
1114 int n_op = n->Opcode();
1115 if (n_op == Op_MergeMem) {
1116 return n;
1117 }
1118 if (n->is_Proj()) {
1119 return n;
1120 }
1121 // Do not clone-up CmpFXXX variations, as these are always
1122 // followed by a CmpI
1123 if (n->is_Cmp()) {
1124 return n;
1125 }
1126 // Attempt to use a conditional move instead of a phi/branch
1127 if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1128 Node *cmov = conditional_move( n );
1129 if (cmov) {
1130 return cmov;
1131 }
1132 }
1133 if (n->is_CFG() || n->is_LoadStore()) {
1134 return n;
1135 }
1136 if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1137 if (!C->major_progress()) { // If chance of no more loop opts...
1138 _igvn._worklist.push(n); // maybe we'll remove them
1139 }
1140 return n;
1141 }
1142
1143 if (n->is_Con()) {
1144 return n; // No cloning for Con nodes
1145 }
1146
1147 Node *n_ctrl = get_ctrl(n);
1148 if (!n_ctrl) {
1149 return n; // Dead node
1150 }
1151
1152 Node* res = try_move_store_before_loop(n, n_ctrl);
1153 if (res != nullptr) {
1154 return n;
1155 }
1156
1157 // Attempt to remix address expressions for loop invariants
1158 Node *m = remix_address_expressions( n );
1159 if( m ) return m;
1160
1161 if (n_op == Op_AddI) {
1162 Node *nn = convert_add_to_muladd( n );
1163 if ( nn ) return nn;
1164 }
1165
1166 if (n->is_ConstraintCast()) {
1167 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1168 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1169 // Node control inputs don't necessarily agree with loop control info (due to
1170 // transformations happened in between), thus additional dominance check is needed
1171 // to keep loop info valid.
1172 if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1173 _igvn.replace_node(n, dom_cast);
1174 return dom_cast;
1175 }
1176 }
1177
1178 // Determine if the Node has inputs from some local Phi.
1179 // Returns the block to clone thru.
1180 Node *n_blk = has_local_phi_input( n );
1181 if( !n_blk ) return n;
1182
1183 // Do not clone the trip counter through on a CountedLoop
1184 // (messes up the canonical shape).
1185 if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1186 (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1187 return n;
1188 }
1189 // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1190 if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1191 n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1192 return n;
1193 }
1194
1195 if (split_thru_phi_could_prevent_vectorization(n, n_blk)) {
1196 return n;
1197 }
1198
1199 // Check for having no control input; not pinned. Allow
1200 // dominating control.
1201 if (n->in(0)) {
1202 Node *dom = idom(n_blk);
1203 if (dom_lca(n->in(0), dom) != n->in(0)) {
1204 return n;
1205 }
1206 }
1207 // Policy: when is it profitable. You must get more wins than
1208 // policy before it is considered profitable. Policy is usually 0,
1209 // so 1 win is considered profitable. Big merges will require big
1210 // cloning, so get a larger policy.
1211 int policy = n_blk->req() >> 2;
1212
1213 // If the loop is a candidate for range check elimination,
1214 // delay splitting through it's phi until a later loop optimization
1215 if (n_blk->is_BaseCountedLoop()) {
1216 IdealLoopTree *lp = get_loop(n_blk);
1217 if (lp && lp->_rce_candidate) {
1218 return n;
1219 }
1220 }
1221
1222 if (must_throttle_split_if()) return n;
1223
1224 // Split 'n' through the merge point if it is profitable
1225 Node *phi = split_thru_phi( n, n_blk, policy );
1226 if (!phi) return n;
1227
1228 // Found a Phi to split thru!
1229 // Replace 'n' with the new phi
1230 _igvn.replace_node( n, phi );
1231 // Moved a load around the loop, 'en-registering' something.
1232 if (n_blk->is_Loop() && n->is_Load() &&
1233 !phi->in(LoopNode::LoopBackControl)->is_Load())
1234 C->set_major_progress();
1235
1236 return phi;
1237 }
1238
1239 static bool merge_point_too_heavy(Compile* C, Node* region) {
1240 // Bail out if the region and its phis have too many users.
1241 int weight = 0;
1242 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1243 weight += region->fast_out(i)->outcnt();
1244 }
1245 int nodes_left = C->max_node_limit() - C->live_nodes();
1246 if (weight * 8 > nodes_left) {
1247 if (PrintOpto) {
1248 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1249 }
1250 return true;
1251 } else {
1252 return false;
1253 }
1254 }
1255
1256 static bool merge_point_safe(Node* region) {
1257 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1258 // having a PhiNode input. This sidesteps the dangerous case where the split
1259 // ConvI2LNode may become TOP if the input Value() does not
1260 // overlap the ConvI2L range, leaving a node which may not dominate its
1261 // uses.
1262 // A better fix for this problem can be found in the BugTraq entry, but
1263 // expediency for Mantis demands this hack.
1264 #ifdef _LP64
1265 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1266 Node* n = region->fast_out(i);
1267 if (n->is_Phi()) {
1268 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1269 Node* m = n->fast_out(j);
1270 if (m->Opcode() == Op_ConvI2L)
1271 return false;
1272 if (m->is_CastII()) {
1273 return false;
1274 }
1275 }
1276 }
1277 }
1278 #endif
1279 return true;
1280 }
1281
1282
1283 //------------------------------place_outside_loop---------------------------------
1284 // Place some computation outside of this loop on the path to the use passed as argument
1285 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1286 Node* head = loop->_head;
1287 assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1288 if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1289 loop = loop->_parent;
1290 assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1291 }
1292
1293 // Pick control right outside the loop
1294 for (;;) {
1295 Node* dom = idom(useblock);
1296 if (loop->is_member(get_loop(dom))) {
1297 break;
1298 }
1299 useblock = dom;
1300 }
1301 assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1302 return useblock;
1303 }
1304
1305
1306 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1307 if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1308 return false;
1309 }
1310 if (!n->in(0)->is_Region()) {
1311 return false;
1312 }
1313
1314 Node* region = n->in(0);
1315 Node* dom = idom(region);
1316 if (!dom->is_If() || !n->as_If()->same_condition(dom, &_igvn)) {
1317 return false;
1318 }
1319 IfNode* dom_if = dom->as_If();
1320 Node* proj_true = dom_if->proj_out(1);
1321 Node* proj_false = dom_if->proj_out(0);
1322
1323 for (uint i = 1; i < region->req(); i++) {
1324 if (is_dominator(proj_true, region->in(i))) {
1325 continue;
1326 }
1327 if (is_dominator(proj_false, region->in(i))) {
1328 continue;
1329 }
1330 return false;
1331 }
1332
1333 return true;
1334 }
1335
1336
1337 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1338 if (must_throttle_split_if()) {
1339 return false;
1340 }
1341
1342 // Do not do 'split-if' if irreducible loops are present.
1343 if (_has_irreducible_loops) {
1344 return false;
1345 }
1346
1347 if (merge_point_too_heavy(C, n_ctrl)) {
1348 return false;
1349 }
1350
1351 // Do not do 'split-if' if some paths are dead. First do dead code
1352 // elimination and then see if its still profitable.
1353 for (uint i = 1; i < n_ctrl->req(); i++) {
1354 if (n_ctrl->in(i) == C->top()) {
1355 return false;
1356 }
1357 }
1358
1359 // If trying to do a 'Split-If' at the loop head, it is only
1360 // profitable if the cmp folds up on BOTH paths. Otherwise we
1361 // risk peeling a loop forever.
1362
1363 // CNC - Disabled for now. Requires careful handling of loop
1364 // body selection for the cloned code. Also, make sure we check
1365 // for any input path not being in the same loop as n_ctrl. For
1366 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1367 // because the alternative loop entry points won't be converted
1368 // into LoopNodes.
1369 IdealLoopTree *n_loop = get_loop(n_ctrl);
1370 for (uint j = 1; j < n_ctrl->req(); j++) {
1371 if (get_loop(n_ctrl->in(j)) != n_loop) {
1372 return false;
1373 }
1374 }
1375
1376 // Check for safety of the merge point.
1377 if (!merge_point_safe(n_ctrl)) {
1378 return false;
1379 }
1380
1381 return true;
1382 }
1383
1384 // Detect if the node is the inner strip-mined loop
1385 // Return: null if it's not the case, or the exit of outer strip-mined loop
1386 static Node* is_inner_of_stripmined_loop(const Node* out) {
1387 Node* out_le = nullptr;
1388
1389 if (out->is_CountedLoopEnd()) {
1390 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1391
1392 if (loop != nullptr && loop->is_strip_mined()) {
1393 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1394 }
1395 }
1396
1397 return out_le;
1398 }
1399
1400 //------------------------------split_if_with_blocks_post----------------------
1401 // Do the real work in a non-recursive function. CFG hackery wants to be
1402 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1403 // info.
1404 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1405
1406 // Cloning Cmp through Phi's involves the split-if transform.
1407 // FastLock is not used by an If
1408 if (n->is_Cmp() && !n->is_FastLock()) {
1409 Node *n_ctrl = get_ctrl(n);
1410 // Determine if the Node has inputs from some local Phi.
1411 // Returns the block to clone thru.
1412 Node *n_blk = has_local_phi_input(n);
1413 if (n_blk != n_ctrl) {
1414 return;
1415 }
1416
1417 if (!can_split_if(n_ctrl)) {
1418 return;
1419 }
1420
1421 if (n->outcnt() != 1) {
1422 return; // Multiple bool's from 1 compare?
1423 }
1424 Node *bol = n->unique_out();
1425 assert(bol->is_Bool(), "expect a bool here");
1426 if (bol->outcnt() != 1) {
1427 return;// Multiple branches from 1 compare?
1428 }
1429 Node *iff = bol->unique_out();
1430
1431 // Check some safety conditions
1432 if (iff->is_If()) { // Classic split-if?
1433 if (iff->in(0) != n_ctrl) {
1434 return; // Compare must be in same blk as if
1435 }
1436 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1437 // Can't split CMove with different control.
1438 if (get_ctrl(iff) != n_ctrl) {
1439 return;
1440 }
1441 if (get_ctrl(iff->in(2)) == n_ctrl ||
1442 get_ctrl(iff->in(3)) == n_ctrl) {
1443 return; // Inputs not yet split-up
1444 }
1445 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1446 return; // Loop-invar test gates loop-varying CMOVE
1447 }
1448 } else {
1449 return; // some other kind of node, such as an Allocate
1450 }
1451
1452 // When is split-if profitable? Every 'win' on means some control flow
1453 // goes dead, so it's almost always a win.
1454 int policy = 0;
1455 // Split compare 'n' through the merge point if it is profitable
1456 Node *phi = split_thru_phi( n, n_ctrl, policy);
1457 if (!phi) {
1458 return;
1459 }
1460
1461 // Found a Phi to split thru!
1462 // Replace 'n' with the new phi
1463 _igvn.replace_node(n, phi);
1464
1465 // Now split the bool up thru the phi
1466 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1467 guarantee(bolphi != nullptr, "null boolean phi node");
1468
1469 _igvn.replace_node(bol, bolphi);
1470 assert(iff->in(1) == bolphi, "");
1471
1472 if (bolphi->Value(&_igvn)->singleton()) {
1473 return;
1474 }
1475
1476 // Conditional-move? Must split up now
1477 if (!iff->is_If()) {
1478 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1479 _igvn.replace_node(iff, cmovphi);
1480 return;
1481 }
1482
1483 // Now split the IF
1484 C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1485 if ((PrintOpto && VerifyLoopOptimizations) || TraceLoopOpts) {
1486 tty->print_cr("Split-If");
1487 }
1488 do_split_if(iff);
1489 C->print_method(PHASE_AFTER_SPLIT_IF, 4, iff);
1490 return;
1491 }
1492
1493 // Two identical ifs back to back can be merged
1494 if (try_merge_identical_ifs(n)) {
1495 return;
1496 }
1497
1498 // Check for an IF ready to split; one that has its
1499 // condition codes input coming from a Phi at the block start.
1500 int n_op = n->Opcode();
1501
1502 // Check for an IF being dominated by another IF same test
1503 if (n_op == Op_If ||
1504 n_op == Op_RangeCheck) {
1505 Node *bol = n->in(1);
1506 uint max = bol->outcnt();
1507 // Check for same test used more than once?
1508 if (bol->is_Bool() && (max > 1 || bol->in(1)->is_SubTypeCheck())) {
1509 // Search up IDOMs to see if this IF is dominated.
1510 Node* cmp = bol->in(1);
1511 Node *cutoff = cmp->is_SubTypeCheck() ? dom_lca(get_ctrl(cmp->in(1)), get_ctrl(cmp->in(2))) : get_ctrl(bol);
1512
1513 // Now search up IDOMs till cutoff, looking for a dominating test
1514 Node *prevdom = n;
1515 Node *dom = idom(prevdom);
1516 while (dom != cutoff) {
1517 if (dom->req() > 1 && n->as_If()->same_condition(dom, &_igvn) && prevdom->in(0) == dom &&
1518 safe_for_if_replacement(dom)) {
1519 // It's invalid to move control dependent data nodes in the inner
1520 // strip-mined loop, because:
1521 // 1) break validation of LoopNode::verify_strip_mined()
1522 // 2) move code with side-effect in strip-mined loop
1523 // Move to the exit of outer strip-mined loop in that case.
1524 Node* out_le = is_inner_of_stripmined_loop(dom);
1525 if (out_le != nullptr) {
1526 prevdom = out_le;
1527 }
1528 // Replace the dominated test with an obvious true or false.
1529 // Place it on the IGVN worklist for later cleanup.
1530 C->set_major_progress();
1531 // Split if: pin array accesses that are control dependent on a range check and moved to a regular if,
1532 // to prevent an array load from floating above its range check. There are three cases:
1533 // 1. Move from RangeCheck "a" to RangeCheck "b": don't need to pin. If we ever remove b, then we pin
1534 // all its array accesses at that point.
1535 // 2. We move from RangeCheck "a" to regular if "b": need to pin. If we ever remove b, then its array
1536 // accesses would start to float, since we don't pin at that point.
1537 // 3. If we move from regular if: don't pin. All array accesses are already assumed to be pinned.
1538 bool pin_array_access_nodes = n->Opcode() == Op_RangeCheck &&
1539 prevdom->in(0)->Opcode() != Op_RangeCheck;
1540 dominated_by(prevdom->as_IfProj(), n->as_If(), false, pin_array_access_nodes);
1541 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1542 return;
1543 }
1544 prevdom = dom;
1545 dom = idom(prevdom);
1546 }
1547 }
1548 }
1549
1550 try_sink_out_of_loop(n);
1551 if (C->failing()) {
1552 return;
1553 }
1554
1555 try_move_store_after_loop(n);
1556 }
1557
1558 // Transform:
1559 //
1560 // if (some_condition) {
1561 // // body 1
1562 // } else {
1563 // // body 2
1564 // }
1565 // if (some_condition) {
1566 // // body 3
1567 // } else {
1568 // // body 4
1569 // }
1570 //
1571 // into:
1572 //
1573 //
1574 // if (some_condition) {
1575 // // body 1
1576 // // body 3
1577 // } else {
1578 // // body 2
1579 // // body 4
1580 // }
1581 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1582 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1583 Node *n_ctrl = n->in(0);
1584 IfNode* dom_if = idom(n_ctrl)->as_If();
1585 if (n->in(1) != dom_if->in(1)) {
1586 assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1587 (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1588 dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1589 _igvn.replace_input_of(n, 1, dom_if->in(1));
1590 }
1591 ProjNode* dom_proj_true = dom_if->proj_out(1);
1592 ProjNode* dom_proj_false = dom_if->proj_out(0);
1593
1594 // Now split the IF
1595 RegionNode* new_false_region;
1596 RegionNode* new_true_region;
1597 do_split_if(n, &new_false_region, &new_true_region);
1598 assert(new_false_region->req() == new_true_region->req(), "");
1599 #ifdef ASSERT
1600 for (uint i = 1; i < new_false_region->req(); ++i) {
1601 assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1602 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");
1603 }
1604 #endif
1605 assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1606
1607 // We now have:
1608 // if (some_condition) {
1609 // // body 1
1610 // if (some_condition) {
1611 // body3: // new_true_region
1612 // // body3
1613 // } else {
1614 // goto body4;
1615 // }
1616 // } else {
1617 // // body 2
1618 // if (some_condition) {
1619 // goto body3;
1620 // } else {
1621 // body4: // new_false_region
1622 // // body4;
1623 // }
1624 // }
1625 //
1626
1627 // clone pinned nodes thru the resulting regions
1628 push_pinned_nodes_thru_region(dom_if, new_true_region);
1629 push_pinned_nodes_thru_region(dom_if, new_false_region);
1630
1631 // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1632 // 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
1633 // unrelated control dependency.
1634 for (uint i = 1; i < new_false_region->req(); i++) {
1635 if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1636 dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1637 } else {
1638 assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1639 dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1640 }
1641 }
1642 return true;
1643 }
1644 return false;
1645 }
1646
1647 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1648 for (DUIterator i = region->outs(); region->has_out(i); i++) {
1649 Node* u = region->out(i);
1650 if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1651 continue;
1652 }
1653 assert(u->in(0) == region, "not a control dependent node?");
1654 uint j = 1;
1655 for (; j < u->req(); ++j) {
1656 Node* in = u->in(j);
1657 if (!is_dominator(ctrl_or_self(in), dom_if)) {
1658 break;
1659 }
1660 }
1661 if (j == u->req()) {
1662 Node *phi = PhiNode::make_blank(region, u);
1663 for (uint k = 1; k < region->req(); ++k) {
1664 Node* clone = u->clone();
1665 clone->set_req(0, region->in(k));
1666 register_new_node(clone, region->in(k));
1667 phi->init_req(k, clone);
1668 }
1669 register_new_node(phi, region);
1670 _igvn.replace_node(u, phi);
1671 --i;
1672 }
1673 }
1674 }
1675
1676 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1677 if (!dom->is_CountedLoopEnd()) {
1678 return true;
1679 }
1680 CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1681 CountedLoopNode* cl = le->loopnode();
1682 if (cl == nullptr) {
1683 return true;
1684 }
1685 if (!cl->is_main_loop()) {
1686 return true;
1687 }
1688 if (cl->is_canonical_loop_entry() == nullptr) {
1689 return true;
1690 }
1691 // Further unrolling is possible so loop exit condition might change
1692 return false;
1693 }
1694
1695 // See if a shared loop-varying computation has no loop-varying uses.
1696 // Happens if something is only used for JVM state in uncommon trap exits,
1697 // like various versions of induction variable+offset. Clone the
1698 // computation per usage to allow it to sink out of the loop.
1699 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1700 if (has_ctrl(n) &&
1701 !n->is_Phi() &&
1702 !n->is_Bool() &&
1703 !n->is_Proj() &&
1704 !n->is_MergeMem() &&
1705 !n->is_CMove() &&
1706 !n->is_OpaqueNotNull() &&
1707 !n->is_OpaqueInitializedAssertionPredicate() &&
1708 !n->is_OpaqueTemplateAssertionPredicate() &&
1709 !n->is_Type()) {
1710 Node *n_ctrl = get_ctrl(n);
1711 IdealLoopTree *n_loop = get_loop(n_ctrl);
1712
1713 if (n->in(0) != nullptr) {
1714 IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1715 if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1716 // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1717 // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1718 // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1719 Node* maybe_pinned_n = n;
1720 Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1721 if (n->depends_only_on_test()) {
1722 Node* pinned_clone = n->pin_array_access_node();
1723 if (pinned_clone != nullptr) {
1724 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1725 // range check for that access. If that condition is replaced by an identical dominating one, then an
1726 // unpinned load would risk floating above its range check.
1727 register_new_node(pinned_clone, n_ctrl);
1728 maybe_pinned_n = pinned_clone;
1729 _igvn.replace_node(n, pinned_clone);
1730 }
1731 }
1732 _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1733 }
1734 }
1735 if (n_loop != _ltree_root && n->outcnt() > 1) {
1736 // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1737 // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1738 Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1739 if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1740 ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1741 if (n->is_Store() || n->is_LoadStore()) {
1742 assert(false, "no node with a side effect");
1743 C->record_failure("no node with a side effect");
1744 return;
1745 }
1746 Node* outer_loop_clone = nullptr;
1747 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1748 Node* u = n->last_out(j); // Clone private computation per use
1749 _igvn.rehash_node_delayed(u);
1750 Node* x = nullptr;
1751 if (n->depends_only_on_test()) {
1752 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1753 // range check for that access. If that condition is replaced by an identical dominating one, then an
1754 // unpinned load would risk floating above its range check.
1755 x = n->pin_array_access_node();
1756 }
1757 if (x == nullptr) {
1758 x = n->clone();
1759 }
1760 Node* x_ctrl = nullptr;
1761 if (u->is_Phi()) {
1762 // Replace all uses of normal nodes. Replace Phi uses
1763 // individually, so the separate Nodes can sink down
1764 // different paths.
1765 uint k = 1;
1766 while (u->in(k) != n) k++;
1767 u->set_req(k, x);
1768 // x goes next to Phi input path
1769 x_ctrl = u->in(0)->in(k);
1770 // Find control for 'x' next to use but not inside inner loops.
1771 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1772 --j;
1773 } else { // Normal use
1774 if (has_ctrl(u)) {
1775 x_ctrl = get_ctrl(u);
1776 } else {
1777 x_ctrl = u->in(0);
1778 }
1779 // Find control for 'x' next to use but not inside inner loops.
1780 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1781 // Replace all uses
1782 if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1783 // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1784 // anymore now that we're going to pin n as well
1785 _igvn.replace_node(u, x);
1786 --j;
1787 } else {
1788 int nb = u->replace_edge(n, x, &_igvn);
1789 j -= nb;
1790 }
1791 }
1792
1793 if (n->is_Load()) {
1794 // For loads, add a control edge to a CFG node outside of the loop
1795 // to force them to not combine and return back inside the loop
1796 // during GVN optimization (4641526).
1797 assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1798
1799 IdealLoopTree* x_loop = get_loop(x_ctrl);
1800 Node* x_head = x_loop->_head;
1801 if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1802 // Do not add duplicate LoadNodes to the outer strip mined loop
1803 if (outer_loop_clone != nullptr) {
1804 _igvn.replace_node(x, outer_loop_clone);
1805 continue;
1806 }
1807 outer_loop_clone = x;
1808 }
1809 x->set_req(0, x_ctrl);
1810 } else if (n->in(0) != nullptr){
1811 x->set_req(0, x_ctrl);
1812 }
1813 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1814 assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1815 register_new_node(x, x_ctrl);
1816
1817 // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
1818 // All AddP nodes must keep the same base after sinking so:
1819 // 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,
1820 // their bases remain the same.
1821 // (see 2- below)
1822 assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1823 x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1824 !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1825 if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
1826 !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1827 assert(!x->is_Load(), "load should be pinned");
1828 // Use a cast node to pin clone out of loop
1829 Node* cast = nullptr;
1830 for (uint k = 0; k < x->req(); k++) {
1831 Node* in = x->in(k);
1832 if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
1833 const Type* in_t = _igvn.type(in);
1834 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
1835 ConstraintCastNode::UnconditionalDependency, nullptr);
1836 }
1837 if (cast != nullptr) {
1838 Node* prev = _igvn.hash_find_insert(cast);
1839 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
1840 cast->destruct(&_igvn);
1841 cast = prev;
1842 } else {
1843 register_new_node(cast, x_ctrl);
1844 }
1845 x->replace_edge(in, cast);
1846 // Chain of AddP nodes:
1847 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
1848 if (x->is_AddP() && k == AddPNode::Base) {
1849 update_addp_chain_base(x, n->in(AddPNode::Base), cast);
1850 }
1851 break;
1852 }
1853 }
1854 assert(cast != nullptr, "must have added a cast to pin the node");
1855 }
1856 }
1857 _igvn.remove_dead_node(n);
1858 }
1859 _dom_lca_tags_round = 0;
1860 }
1861 }
1862 }
1863
1864 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
1865 ResourceMark rm;
1866 Node_List wq;
1867 wq.push(x);
1868 while (wq.size() != 0) {
1869 Node* n = wq.pop();
1870 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1871 Node* u = n->fast_out(i);
1872 if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
1873 _igvn.replace_input_of(u, AddPNode::Base, new_base);
1874 wq.push(u);
1875 }
1876 }
1877 }
1878 }
1879
1880 // Compute the early control of a node by following its inputs until we reach
1881 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
1882 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
1883 Node* early_ctrl = nullptr;
1884 ResourceMark rm;
1885 Unique_Node_List wq;
1886 wq.push(n);
1887 for (uint i = 0; i < wq.size(); i++) {
1888 Node* m = wq.at(i);
1889 Node* c = nullptr;
1890 if (m->is_CFG()) {
1891 c = m;
1892 } else if (m->pinned()) {
1893 c = m->in(0);
1894 } else {
1895 for (uint j = 0; j < m->req(); j++) {
1896 Node* in = m->in(j);
1897 if (in != nullptr) {
1898 wq.push(in);
1899 }
1900 }
1901 }
1902 if (c != nullptr) {
1903 assert(is_dominator(c, n_ctrl), "control input must dominate current control");
1904 if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
1905 early_ctrl = c;
1906 }
1907 }
1908 }
1909 assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
1910 return early_ctrl;
1911 }
1912
1913 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
1914 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1915 Node* u = n->fast_out(i);
1916 if (u->is_Opaque1()) {
1917 return false; // Found loop limit, bugfix for 4677003
1918 }
1919 // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
1920 // get_late_ctrl_with_anti_dep() use their own tag
1921 _dom_lca_tags_round++;
1922 assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
1923
1924 if (u->is_Phi()) {
1925 for (uint j = 1; j < u->req(); ++j) {
1926 if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
1927 return false;
1928 }
1929 }
1930 } else {
1931 Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
1932 if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
1933 return false;
1934 }
1935 }
1936 }
1937 return true;
1938 }
1939
1940 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
1941 if (n->is_Load()) {
1942 ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
1943 }
1944 IdealLoopTree *u_loop = get_loop(ctrl);
1945 if (u_loop == n_loop) {
1946 return false; // Found loop-varying use
1947 }
1948 if (n_loop->is_member(u_loop)) {
1949 return false; // Found use in inner loop
1950 }
1951 // 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
1952 // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
1953 // test of the pre loop above the point in the graph where it's pinned.
1954 if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
1955 CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
1956 if (is_dominator(pre_loop->loopexit(), ctrl)) {
1957 return false;
1958 }
1959 }
1960 return true;
1961 }
1962
1963 //------------------------------split_if_with_blocks---------------------------
1964 // Check for aggressive application of 'split-if' optimization,
1965 // using basic block level info.
1966 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1967 Node* root = C->root();
1968 visited.set(root->_idx); // first, mark root as visited
1969 // Do pre-visit work for root
1970 Node* n = split_if_with_blocks_pre(root);
1971 uint cnt = n->outcnt();
1972 uint i = 0;
1973
1974 while (true) {
1975 // Visit all children
1976 if (i < cnt) {
1977 Node* use = n->raw_out(i);
1978 ++i;
1979 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1980 // Now do pre-visit work for this use
1981 use = split_if_with_blocks_pre(use);
1982 nstack.push(n, i); // Save parent and next use's index.
1983 n = use; // Process all children of current use.
1984 cnt = use->outcnt();
1985 i = 0;
1986 }
1987 }
1988 else {
1989 // All of n's children have been processed, complete post-processing.
1990 if (cnt != 0 && !n->is_Con()) {
1991 assert(has_node(n), "no dead nodes");
1992 split_if_with_blocks_post(n);
1993 if (C->failing()) {
1994 return;
1995 }
1996 }
1997 if (must_throttle_split_if()) {
1998 nstack.clear();
1999 }
2000 if (nstack.is_empty()) {
2001 // Finished all nodes on stack.
2002 break;
2003 }
2004 // Get saved parent node and next use's index. Visit the rest of uses.
2005 n = nstack.node();
2006 cnt = n->outcnt();
2007 i = nstack.index();
2008 nstack.pop();
2009 }
2010 }
2011 }
2012
2013
2014 //=============================================================================
2015 //
2016 // C L O N E A L O O P B O D Y
2017 //
2018
2019 //------------------------------clone_iff--------------------------------------
2020 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2021 // "Nearly" because all Nodes have been cloned from the original in the loop,
2022 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2023 // through the Phi recursively, and return a Bool.
2024 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2025
2026 // Convert this Phi into a Phi merging Bools
2027 uint i;
2028 for (i = 1; i < phi->req(); i++) {
2029 Node* b = phi->in(i);
2030 if (b->is_Phi()) {
2031 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2032 } else {
2033 assert(b->is_Bool() || b->is_OpaqueNotNull() || b->is_OpaqueInitializedAssertionPredicate(),
2034 "bool, non-null check with OpaqueNotNull or Initialized Assertion Predicate with its Opaque node");
2035 }
2036 }
2037 Node* n = phi->in(1);
2038 Node* sample_opaque = nullptr;
2039 Node *sample_bool = nullptr;
2040 if (n->is_OpaqueNotNull() || n->is_OpaqueInitializedAssertionPredicate()) {
2041 sample_opaque = n;
2042 sample_bool = n->in(1);
2043 assert(sample_bool->is_Bool(), "wrong type");
2044 } else {
2045 sample_bool = n;
2046 }
2047 Node *sample_cmp = sample_bool->in(1);
2048
2049 // Make Phis to merge the Cmp's inputs.
2050 PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
2051 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2052 for (i = 1; i < phi->req(); i++) {
2053 Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2054 Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2055 phi1->set_req(i, n1);
2056 phi2->set_req(i, n2);
2057 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2058 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2059 }
2060 // See if these Phis have been made before.
2061 // Register with optimizer
2062 Node *hit1 = _igvn.hash_find_insert(phi1);
2063 if (hit1) { // Hit, toss just made Phi
2064 _igvn.remove_dead_node(phi1); // Remove new phi
2065 assert(hit1->is_Phi(), "" );
2066 phi1 = (PhiNode*)hit1; // Use existing phi
2067 } else { // Miss
2068 _igvn.register_new_node_with_optimizer(phi1);
2069 }
2070 Node *hit2 = _igvn.hash_find_insert(phi2);
2071 if (hit2) { // Hit, toss just made Phi
2072 _igvn.remove_dead_node(phi2); // Remove new phi
2073 assert(hit2->is_Phi(), "" );
2074 phi2 = (PhiNode*)hit2; // Use existing phi
2075 } else { // Miss
2076 _igvn.register_new_node_with_optimizer(phi2);
2077 }
2078 // Register Phis with loop/block info
2079 set_ctrl(phi1, phi->in(0));
2080 set_ctrl(phi2, phi->in(0));
2081 // Make a new Cmp
2082 Node *cmp = sample_cmp->clone();
2083 cmp->set_req(1, phi1);
2084 cmp->set_req(2, phi2);
2085 _igvn.register_new_node_with_optimizer(cmp);
2086 set_ctrl(cmp, phi->in(0));
2087
2088 // Make a new Bool
2089 Node *b = sample_bool->clone();
2090 b->set_req(1,cmp);
2091 _igvn.register_new_node_with_optimizer(b);
2092 set_ctrl(b, phi->in(0));
2093
2094 if (sample_opaque != nullptr) {
2095 Node* opaque = sample_opaque->clone();
2096 opaque->set_req(1, b);
2097 _igvn.register_new_node_with_optimizer(opaque);
2098 set_ctrl(opaque, phi->in(0));
2099 return opaque;
2100 }
2101
2102 assert(b->is_Bool(), "");
2103 return b;
2104 }
2105
2106 //------------------------------clone_bool-------------------------------------
2107 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2108 // "Nearly" because all Nodes have been cloned from the original in the loop,
2109 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2110 // through the Phi recursively, and return a Bool.
2111 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2112 uint i;
2113 // Convert this Phi into a Phi merging Bools
2114 for( i = 1; i < phi->req(); i++ ) {
2115 Node *b = phi->in(i);
2116 if( b->is_Phi() ) {
2117 _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2118 } else {
2119 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2120 }
2121 }
2122
2123 Node *sample_cmp = phi->in(1);
2124
2125 // Make Phis to merge the Cmp's inputs.
2126 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2127 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2128 for( uint j = 1; j < phi->req(); j++ ) {
2129 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2130 Node *n1, *n2;
2131 if( cmp_top->is_Cmp() ) {
2132 n1 = cmp_top->in(1);
2133 n2 = cmp_top->in(2);
2134 } else {
2135 n1 = n2 = cmp_top;
2136 }
2137 phi1->set_req( j, n1 );
2138 phi2->set_req( j, n2 );
2139 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2140 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2141 }
2142
2143 // See if these Phis have been made before.
2144 // Register with optimizer
2145 Node *hit1 = _igvn.hash_find_insert(phi1);
2146 if( hit1 ) { // Hit, toss just made Phi
2147 _igvn.remove_dead_node(phi1); // Remove new phi
2148 assert( hit1->is_Phi(), "" );
2149 phi1 = (PhiNode*)hit1; // Use existing phi
2150 } else { // Miss
2151 _igvn.register_new_node_with_optimizer(phi1);
2152 }
2153 Node *hit2 = _igvn.hash_find_insert(phi2);
2154 if( hit2 ) { // Hit, toss just made Phi
2155 _igvn.remove_dead_node(phi2); // Remove new phi
2156 assert( hit2->is_Phi(), "" );
2157 phi2 = (PhiNode*)hit2; // Use existing phi
2158 } else { // Miss
2159 _igvn.register_new_node_with_optimizer(phi2);
2160 }
2161 // Register Phis with loop/block info
2162 set_ctrl(phi1, phi->in(0));
2163 set_ctrl(phi2, phi->in(0));
2164 // Make a new Cmp
2165 Node *cmp = sample_cmp->clone();
2166 cmp->set_req( 1, phi1 );
2167 cmp->set_req( 2, phi2 );
2168 _igvn.register_new_node_with_optimizer(cmp);
2169 set_ctrl(cmp, phi->in(0));
2170
2171 assert( cmp->is_Cmp(), "" );
2172 return (CmpNode*)cmp;
2173 }
2174
2175 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2176 IdealLoopTree* loop, IdealLoopTree* outer_loop,
2177 Node_List*& split_if_set, Node_List*& split_bool_set,
2178 Node_List*& split_cex_set, Node_List& worklist,
2179 uint new_counter, CloneLoopMode mode) {
2180 Node* nnn = old_new[old->_idx];
2181 // Copy uses to a worklist, so I can munge the def-use info
2182 // with impunity.
2183 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2184 worklist.push(old->fast_out(j));
2185
2186 while( worklist.size() ) {
2187 Node *use = worklist.pop();
2188 if (!has_node(use)) continue; // Ignore dead nodes
2189 if (use->in(0) == C->top()) continue;
2190 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2191 // Check for data-use outside of loop - at least one of OLD or USE
2192 // must not be a CFG node.
2193 #ifdef ASSERT
2194 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2195 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2196 assert(mode != IgnoreStripMined, "incorrect cloning mode");
2197 assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2198 }
2199 #endif
2200 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2201
2202 // If the Data use is an IF, that means we have an IF outside the
2203 // loop that is switching on a condition that is set inside the
2204 // loop. Happens if people set a loop-exit flag; then test the flag
2205 // in the loop to break the loop, then test is again outside the
2206 // loop to determine which way the loop exited.
2207 //
2208 // For several uses we need to make sure that there is no phi between,
2209 // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2210 // to avoid such a phi in between.
2211 // For example, it is unexpected that there is a Phi between an
2212 // AllocateArray node and its ValidLengthTest input that could cause
2213 // split if to break.
2214 assert(!use->is_OpaqueTemplateAssertionPredicate(),
2215 "should not clone a Template Assertion Predicate which should be removed once it's useless");
2216 if (use->is_If() || use->is_CMove() || use->is_OpaqueNotNull() || use->is_OpaqueInitializedAssertionPredicate() ||
2217 (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2218 // Since this code is highly unlikely, we lazily build the worklist
2219 // of such Nodes to go split.
2220 if (!split_if_set) {
2221 split_if_set = new Node_List();
2222 }
2223 split_if_set->push(use);
2224 }
2225 if (use->is_Bool()) {
2226 if (!split_bool_set) {
2227 split_bool_set = new Node_List();
2228 }
2229 split_bool_set->push(use);
2230 }
2231 if (use->Opcode() == Op_CreateEx) {
2232 if (!split_cex_set) {
2233 split_cex_set = new Node_List();
2234 }
2235 split_cex_set->push(use);
2236 }
2237
2238
2239 // Get "block" use is in
2240 uint idx = 0;
2241 while( use->in(idx) != old ) idx++;
2242 Node *prev = use->is_CFG() ? use : get_ctrl(use);
2243 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2244 Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2245 ? prev->in(2)
2246 : idom(prev);
2247 if( use->is_Phi() ) // Phi use is in prior block
2248 cfg = prev->in(idx); // NOT in block of Phi itself
2249 if (cfg->is_top()) { // Use is dead?
2250 _igvn.replace_input_of(use, idx, C->top());
2251 continue;
2252 }
2253
2254 // If use is referenced through control edge... (idx == 0)
2255 if (mode == IgnoreStripMined && idx == 0) {
2256 LoopNode *head = loop->_head->as_Loop();
2257 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2258 // That node is outside the inner loop, leave it outside the
2259 // outer loop as well to not confuse verification code.
2260 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2261 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2262 continue;
2263 }
2264 }
2265
2266 while(!outer_loop->is_member(get_loop(cfg))) {
2267 prev = cfg;
2268 cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2269 }
2270 // If the use occurs after merging several exits from the loop, then
2271 // old value must have dominated all those exits. Since the same old
2272 // value was used on all those exits we did not need a Phi at this
2273 // merge point. NOW we do need a Phi here. Each loop exit value
2274 // is now merged with the peeled body exit; each exit gets its own
2275 // private Phi and those Phis need to be merged here.
2276 Node *phi;
2277 if( prev->is_Region() ) {
2278 if( idx == 0 ) { // Updating control edge?
2279 phi = prev; // Just use existing control
2280 } else { // Else need a new Phi
2281 phi = PhiNode::make( prev, old );
2282 // Now recursively fix up the new uses of old!
2283 for( uint i = 1; i < prev->req(); i++ ) {
2284 worklist.push(phi); // Onto worklist once for each 'old' input
2285 }
2286 }
2287 } else {
2288 // Get new RegionNode merging old and new loop exits
2289 prev = old_new[prev->_idx];
2290 assert( prev, "just made this in step 7" );
2291 if( idx == 0) { // Updating control edge?
2292 phi = prev; // Just use existing control
2293 } else { // Else need a new Phi
2294 // Make a new Phi merging data values properly
2295 phi = PhiNode::make( prev, old );
2296 phi->set_req( 1, nnn );
2297 }
2298 }
2299 // If inserting a new Phi, check for prior hits
2300 if( idx != 0 ) {
2301 Node *hit = _igvn.hash_find_insert(phi);
2302 if( hit == nullptr ) {
2303 _igvn.register_new_node_with_optimizer(phi); // Register new phi
2304 } else { // or
2305 // Remove the new phi from the graph and use the hit
2306 _igvn.remove_dead_node(phi);
2307 phi = hit; // Use existing phi
2308 }
2309 set_ctrl(phi, prev);
2310 }
2311 // Make 'use' use the Phi instead of the old loop body exit value
2312 assert(use->in(idx) == old, "old is still input of use");
2313 // We notify all uses of old, including use, and the indirect uses,
2314 // that may now be optimized because we have replaced old with phi.
2315 _igvn.add_users_to_worklist(old);
2316 if (idx == 0 &&
2317 use->depends_only_on_test()) {
2318 Node* pinned_clone = use->pin_array_access_node();
2319 if (pinned_clone != nullptr) {
2320 // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path
2321 // into the region is left, an array load could become dependent on a condition that's not a range check for
2322 // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
2323 // floating above its range check.
2324 pinned_clone->set_req(0, phi);
2325 register_new_node_with_ctrl_of(pinned_clone, use);
2326 _igvn.replace_node(use, pinned_clone);
2327 continue;
2328 }
2329 }
2330 _igvn.replace_input_of(use, idx, phi);
2331 if( use->_idx >= new_counter ) { // If updating new phis
2332 // Not needed for correctness, but prevents a weak assert
2333 // in AddPNode from tripping (when we end up with different
2334 // base & derived Phis that will become the same after
2335 // IGVN does CSE).
2336 Node *hit = _igvn.hash_find_insert(use);
2337 if( hit ) // Go ahead and re-hash for hits.
2338 _igvn.replace_node( use, hit );
2339 }
2340 }
2341 }
2342 }
2343
2344 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2345 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2346 bool check_old_new) {
2347 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2348 Node* u = n->fast_out(j);
2349 assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2350 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2351 Node* c = phase->get_ctrl(u);
2352 IdealLoopTree* u_loop = phase->get_loop(c);
2353 assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2354 if (!loop->is_member(u_loop)) {
2355 if (outer_loop->is_member(u_loop)) {
2356 wq.push(u);
2357 } else {
2358 // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2359 // the outer loop too
2360 Node* u_c = u->in(0);
2361 if (u_c != nullptr) {
2362 IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2363 if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2364 wq.push(u);
2365 }
2366 }
2367 }
2368 }
2369 }
2370 }
2371 }
2372
2373 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2374 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2375 Node_List& extra_data_nodes) {
2376 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2377 CountedLoopNode* cl = head->as_CountedLoop();
2378 Node* l = cl->outer_loop();
2379 Node* tail = cl->outer_loop_tail();
2380 IfNode* le = cl->outer_loop_end();
2381 Node* sfpt = cl->outer_safepoint();
2382 CountedLoopEndNode* cle = cl->loopexit();
2383 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2384 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2385 Node* cle_out = cle->proj_out(false);
2386
2387 Node* new_sfpt = nullptr;
2388 Node* new_cle_out = cle_out->clone();
2389 old_new.map(cle_out->_idx, new_cle_out);
2390 if (mode == CloneIncludesStripMined) {
2391 // clone outer loop body
2392 Node* new_l = l->clone();
2393 Node* new_tail = tail->clone();
2394 IfNode* new_le = le->clone()->as_If();
2395 new_sfpt = sfpt->clone();
2396
2397 set_loop(new_l, outer_loop->_parent);
2398 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2399 set_loop(new_cle_out, outer_loop->_parent);
2400 set_idom(new_cle_out, new_cle, dd);
2401 set_loop(new_sfpt, outer_loop->_parent);
2402 set_idom(new_sfpt, new_cle_out, dd);
2403 set_loop(new_le, outer_loop->_parent);
2404 set_idom(new_le, new_sfpt, dd);
2405 set_loop(new_tail, outer_loop->_parent);
2406 set_idom(new_tail, new_le, dd);
2407 set_idom(new_cl, new_l, dd);
2408
2409 old_new.map(l->_idx, new_l);
2410 old_new.map(tail->_idx, new_tail);
2411 old_new.map(le->_idx, new_le);
2412 old_new.map(sfpt->_idx, new_sfpt);
2413
2414 new_l->set_req(LoopNode::LoopBackControl, new_tail);
2415 new_l->set_req(0, new_l);
2416 new_tail->set_req(0, new_le);
2417 new_le->set_req(0, new_sfpt);
2418 new_sfpt->set_req(0, new_cle_out);
2419 new_cle_out->set_req(0, new_cle);
2420 new_cl->set_req(LoopNode::EntryControl, new_l);
2421
2422 _igvn.register_new_node_with_optimizer(new_l);
2423 _igvn.register_new_node_with_optimizer(new_tail);
2424 _igvn.register_new_node_with_optimizer(new_le);
2425 } else {
2426 Node *newhead = old_new[loop->_head->_idx];
2427 newhead->as_Loop()->clear_strip_mined();
2428 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2429 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2430 }
2431 // Look at data node that were assigned a control in the outer
2432 // loop: they are kept in the outer loop by the safepoint so start
2433 // from the safepoint node's inputs.
2434 IdealLoopTree* outer_loop = get_loop(l);
2435 Node_Stack stack(2);
2436 stack.push(sfpt, 1);
2437 uint new_counter = C->unique();
2438 while (stack.size() > 0) {
2439 Node* n = stack.node();
2440 uint i = stack.index();
2441 while (i < n->req() &&
2442 (n->in(i) == nullptr ||
2443 !has_ctrl(n->in(i)) ||
2444 get_loop(get_ctrl(n->in(i))) != outer_loop ||
2445 (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2446 i++;
2447 }
2448 if (i < n->req()) {
2449 stack.set_index(i+1);
2450 stack.push(n->in(i), 0);
2451 } else {
2452 assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2453 Node* m = n == sfpt ? new_sfpt : n->clone();
2454 if (m != nullptr) {
2455 for (uint i = 0; i < n->req(); i++) {
2456 if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2457 m->set_req(i, old_new[m->in(i)->_idx]);
2458 }
2459 }
2460 } else {
2461 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2462 }
2463 if (n != sfpt) {
2464 extra_data_nodes.push(n);
2465 _igvn.register_new_node_with_optimizer(m);
2466 assert(get_ctrl(n) == cle_out, "what other control?");
2467 set_ctrl(m, new_cle_out);
2468 old_new.map(n->_idx, m);
2469 }
2470 stack.pop();
2471 }
2472 }
2473 if (mode == CloneIncludesStripMined) {
2474 _igvn.register_new_node_with_optimizer(new_sfpt);
2475 _igvn.register_new_node_with_optimizer(new_cle_out);
2476 }
2477 // Some other transformation may have pessimistically assigned some
2478 // data nodes to the outer loop. Set their control so they are out
2479 // of the outer loop.
2480 ResourceMark rm;
2481 Unique_Node_List wq;
2482 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2483 Node* old = extra_data_nodes.at(i);
2484 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2485 }
2486
2487 for (uint i = 0; i < loop->_body.size(); i++) {
2488 Node* old = loop->_body.at(i);
2489 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2490 }
2491
2492 Node* inner_out = sfpt->in(0);
2493 if (inner_out->outcnt() > 1) {
2494 collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2495 }
2496
2497 Node* new_ctrl = cl->outer_loop_exit();
2498 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2499 for (uint i = 0; i < wq.size(); i++) {
2500 Node* n = wq.at(i);
2501 set_ctrl(n, new_ctrl);
2502 if (n->in(0) != nullptr) {
2503 _igvn.replace_input_of(n, 0, new_ctrl);
2504 }
2505 collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2506 }
2507 } else {
2508 Node *newhead = old_new[loop->_head->_idx];
2509 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2510 }
2511 }
2512
2513 //------------------------------clone_loop-------------------------------------
2514 //
2515 // C L O N E A L O O P B O D Y
2516 //
2517 // This is the basic building block of the loop optimizations. It clones an
2518 // entire loop body. It makes an old_new loop body mapping; with this mapping
2519 // you can find the new-loop equivalent to an old-loop node. All new-loop
2520 // nodes are exactly equal to their old-loop counterparts, all edges are the
2521 // same. All exits from the old-loop now have a RegionNode that merges the
2522 // equivalent new-loop path. This is true even for the normal "loop-exit"
2523 // condition. All uses of loop-invariant old-loop values now come from (one
2524 // or more) Phis that merge their new-loop equivalents.
2525 //
2526 // This operation leaves the graph in an illegal state: there are two valid
2527 // control edges coming from the loop pre-header to both loop bodies. I'll
2528 // definitely have to hack the graph after running this transform.
2529 //
2530 // From this building block I will further edit edges to perform loop peeling
2531 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2532 //
2533 // Parameter side_by_size_idom:
2534 // When side_by_size_idom is null, the dominator tree is constructed for
2535 // the clone loop to dominate the original. Used in construction of
2536 // pre-main-post loop sequence.
2537 // When nonnull, the clone and original are side-by-side, both are
2538 // dominated by the side_by_side_idom node. Used in construction of
2539 // unswitched loops.
2540 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2541 CloneLoopMode mode, Node* side_by_side_idom) {
2542
2543 LoopNode* head = loop->_head->as_Loop();
2544 head->verify_strip_mined(1);
2545
2546 if (C->do_vector_loop() && PrintOpto) {
2547 const char* mname = C->method()->name()->as_quoted_ascii();
2548 if (mname != nullptr) {
2549 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2550 }
2551 }
2552
2553 CloneMap& cm = C->clone_map();
2554 if (C->do_vector_loop()) {
2555 cm.set_clone_idx(cm.max_gen()+1);
2556 #ifndef PRODUCT
2557 if (PrintOpto) {
2558 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2559 loop->dump_head();
2560 }
2561 #endif
2562 }
2563
2564 // Step 1: Clone the loop body. Make the old->new mapping.
2565 clone_loop_body(loop->_body, old_new, &cm);
2566
2567 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2568
2569 // Step 2: Fix the edges in the new body. If the old input is outside the
2570 // loop use it. If the old input is INside the loop, use the corresponding
2571 // new node instead.
2572 fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2573
2574 Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2575 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2576
2577 // Step 3: Now fix control uses. Loop varying control uses have already
2578 // been fixed up (as part of all input edges in Step 2). Loop invariant
2579 // control uses must be either an IfFalse or an IfTrue. Make a merge
2580 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2581 // refer to this.
2582 Node_List worklist;
2583 uint new_counter = C->unique();
2584 fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2585
2586 // Step 4: If loop-invariant use is not control, it must be dominated by a
2587 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2588 // there if needed. Make a Phi there merging old and new used values.
2589 Node_List *split_if_set = nullptr;
2590 Node_List *split_bool_set = nullptr;
2591 Node_List *split_cex_set = nullptr;
2592 fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2593
2594 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2595 Node* old = extra_data_nodes.at(i);
2596 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2597 split_bool_set, split_cex_set, worklist, new_counter,
2598 mode);
2599 }
2600
2601 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2602 // the loop uses a condition set in the loop. The original IF probably
2603 // takes control from one or more OLD Regions (which in turn get from NEW
2604 // Regions). In any case, there will be a set of Phis for each merge point
2605 // from the IF up to where the original BOOL def exists the loop.
2606 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2607
2608 }
2609
2610 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2611 if (split_if_set) {
2612 while (split_if_set->size()) {
2613 Node *iff = split_if_set->pop();
2614 uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2615 if (iff->in(input)->is_Phi()) {
2616 Node *b = clone_iff(iff->in(input)->as_Phi());
2617 _igvn.replace_input_of(iff, input, b);
2618 }
2619 }
2620 }
2621 if (split_bool_set) {
2622 while (split_bool_set->size()) {
2623 Node *b = split_bool_set->pop();
2624 Node *phi = b->in(1);
2625 assert(phi->is_Phi(), "");
2626 CmpNode *cmp = clone_bool((PhiNode*) phi);
2627 _igvn.replace_input_of(b, 1, cmp);
2628 }
2629 }
2630 if (split_cex_set) {
2631 while (split_cex_set->size()) {
2632 Node *b = split_cex_set->pop();
2633 assert(b->in(0)->is_Region(), "");
2634 assert(b->in(1)->is_Phi(), "");
2635 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2636 split_up(b, b->in(0), nullptr);
2637 }
2638 }
2639 }
2640
2641 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2642 uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2643 Node_List*& split_bool_set, Node_List*& split_cex_set) {
2644 for(uint i = 0; i < body.size(); i++ ) {
2645 Node* old = body.at(i);
2646 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2647 split_bool_set, split_cex_set, worklist, new_counter,
2648 mode);
2649 }
2650 }
2651
2652 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2653 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2654 LoopNode* head = loop->_head->as_Loop();
2655 for(uint i = 0; i < body.size(); i++ ) {
2656 Node* old = body.at(i);
2657 if( !old->is_CFG() ) continue;
2658
2659 // Copy uses to a worklist, so I can munge the def-use info
2660 // with impunity.
2661 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2662 worklist.push(old->fast_out(j));
2663 }
2664
2665 while (worklist.size()) { // Visit all uses
2666 Node *use = worklist.pop();
2667 if (!has_node(use)) continue; // Ignore dead nodes
2668 IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2669 if (!loop->is_member(use_loop) && use->is_CFG()) {
2670 // Both OLD and USE are CFG nodes here.
2671 assert(use->is_Proj(), "" );
2672 Node* nnn = old_new[old->_idx];
2673
2674 Node* newuse = nullptr;
2675 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2676 CountedLoopNode* cl = head->as_CountedLoop();
2677 CountedLoopEndNode* cle = cl->loopexit();
2678 Node* cle_out = cle->proj_out_or_null(false);
2679 if (use == cle_out) {
2680 IfNode* le = cl->outer_loop_end();
2681 use = le->proj_out(false);
2682 use_loop = get_loop(use);
2683 if (mode == CloneIncludesStripMined) {
2684 nnn = old_new[le->_idx];
2685 } else {
2686 newuse = old_new[cle_out->_idx];
2687 }
2688 }
2689 }
2690 if (newuse == nullptr) {
2691 newuse = use->clone();
2692 }
2693
2694 // Clone the loop exit control projection
2695 if (C->do_vector_loop() && cm != nullptr) {
2696 cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2697 }
2698 newuse->set_req(0,nnn);
2699 _igvn.register_new_node_with_optimizer(newuse);
2700 set_loop(newuse, use_loop);
2701 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2702
2703 // We need a Region to merge the exit from the peeled body and the
2704 // exit from the old loop body.
2705 RegionNode *r = new RegionNode(3);
2706 uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2707 assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2708
2709 // The original user of 'use' uses 'r' instead.
2710 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2711 Node* useuse = use->last_out(l);
2712 _igvn.rehash_node_delayed(useuse);
2713 uint uses_found = 0;
2714 if (useuse->in(0) == use) {
2715 useuse->set_req(0, r);
2716 uses_found++;
2717 if (useuse->is_CFG()) {
2718 // This is not a dom_depth > dd_r because when new
2719 // control flow is constructed by a loop opt, a node and
2720 // its dominator can end up at the same dom_depth
2721 assert(dom_depth(useuse) >= dd_r, "");
2722 set_idom(useuse, r, dom_depth(useuse));
2723 }
2724 }
2725 for (uint k = 1; k < useuse->req(); k++) {
2726 if( useuse->in(k) == use ) {
2727 useuse->set_req(k, r);
2728 uses_found++;
2729 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2730 // This is not a dom_depth > dd_r because when new
2731 // control flow is constructed by a loop opt, a node
2732 // and its dominator can end up at the same dom_depth
2733 assert(dom_depth(useuse) >= dd_r , "");
2734 set_idom(useuse, r, dom_depth(useuse));
2735 }
2736 }
2737 }
2738 l -= uses_found; // we deleted 1 or more copies of this edge
2739 }
2740
2741 assert(use->is_Proj(), "loop exit should be projection");
2742 // lazy_replace() below moves all nodes that are:
2743 // - control dependent on the loop exit or
2744 // - have control set to the loop exit
2745 // below the post-loop merge point. lazy_replace() takes a dead control as first input. To make it
2746 // possible to use it, the loop exit projection is cloned and becomes the new exit projection. The initial one
2747 // becomes dead and is "replaced" by the region.
2748 Node* use_clone = use->clone();
2749 register_control(use_clone, use_loop, idom(use), dom_depth(use));
2750 // Now finish up 'r'
2751 r->set_req(1, newuse);
2752 r->set_req(2, use_clone);
2753 _igvn.register_new_node_with_optimizer(r);
2754 set_loop(r, use_loop);
2755 set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2756 lazy_replace(use, r);
2757 // Map the (cloned) old use to the new merge point
2758 old_new.map(use_clone->_idx, r);
2759 } // End of if a loop-exit test
2760 }
2761 }
2762 }
2763
2764 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2765 IdealLoopTree* parent, bool partial) {
2766 for(uint i = 0; i < body.size(); i++ ) {
2767 Node *old = body.at(i);
2768 Node *nnn = old_new[old->_idx];
2769 // Fix CFG/Loop controlling the new node
2770 if (has_ctrl(old)) {
2771 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2772 } else {
2773 set_loop(nnn, parent);
2774 if (old->outcnt() > 0) {
2775 Node* dom = idom(old);
2776 if (old_new[dom->_idx] != nullptr) {
2777 dom = old_new[dom->_idx];
2778 set_idom(nnn, dom, dd );
2779 }
2780 }
2781 }
2782 // Correct edges to the new node
2783 for (uint j = 0; j < nnn->req(); j++) {
2784 Node *n = nnn->in(j);
2785 if (n != nullptr) {
2786 IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2787 if (loop->is_member(old_in_loop)) {
2788 if (old_new[n->_idx] != nullptr) {
2789 nnn->set_req(j, old_new[n->_idx]);
2790 } else {
2791 assert(!body.contains(n), "");
2792 assert(partial, "node not cloned");
2793 }
2794 }
2795 }
2796 }
2797 _igvn.hash_find_insert(nnn);
2798 }
2799 }
2800
2801 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2802 for (uint i = 0; i < body.size(); i++) {
2803 Node* old = body.at(i);
2804 Node* nnn = old->clone();
2805 old_new.map(old->_idx, nnn);
2806 if (C->do_vector_loop() && cm != nullptr) {
2807 cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2808 }
2809 _igvn.register_new_node_with_optimizer(nnn);
2810 }
2811 }
2812
2813
2814 //---------------------- stride_of_possible_iv -------------------------------------
2815 // Looks for an iff/bool/comp with one operand of the compare
2816 // being a cycle involving an add and a phi,
2817 // with an optional truncation (left-shift followed by a right-shift)
2818 // of the add. Returns zero if not an iv.
2819 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2820 Node* trunc1 = nullptr;
2821 Node* trunc2 = nullptr;
2822 const TypeInteger* ttype = nullptr;
2823 if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
2824 return 0;
2825 }
2826 BoolNode* bl = iff->in(1)->as_Bool();
2827 Node* cmp = bl->in(1);
2828 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2829 return 0;
2830 }
2831 // Must have an invariant operand
2832 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2833 return 0;
2834 }
2835 Node* add2 = nullptr;
2836 Node* cmp1 = cmp->in(1);
2837 if (cmp1->is_Phi()) {
2838 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2839 Node* phi = cmp1;
2840 for (uint i = 1; i < phi->req(); i++) {
2841 Node* in = phi->in(i);
2842 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2843 &trunc1, &trunc2, &ttype, T_INT);
2844 if (add && add->in(1) == phi) {
2845 add2 = add->in(2);
2846 break;
2847 }
2848 }
2849 } else {
2850 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2851 Node* addtrunc = cmp1;
2852 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2853 &trunc1, &trunc2, &ttype, T_INT);
2854 if (add && add->in(1)->is_Phi()) {
2855 Node* phi = add->in(1);
2856 for (uint i = 1; i < phi->req(); i++) {
2857 if (phi->in(i) == addtrunc) {
2858 add2 = add->in(2);
2859 break;
2860 }
2861 }
2862 }
2863 }
2864 if (add2 != nullptr) {
2865 const TypeInt* add2t = _igvn.type(add2)->is_int();
2866 if (add2t->is_con()) {
2867 return add2t->get_con();
2868 }
2869 }
2870 return 0;
2871 }
2872
2873
2874 //---------------------- stay_in_loop -------------------------------------
2875 // Return the (unique) control output node that's in the loop (if it exists.)
2876 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2877 Node* unique = nullptr;
2878 if (!n) return nullptr;
2879 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2880 Node* use = n->fast_out(i);
2881 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2882 if (unique != nullptr) {
2883 return nullptr;
2884 }
2885 unique = use;
2886 }
2887 }
2888 return unique;
2889 }
2890
2891 //------------------------------ register_node -------------------------------------
2892 // Utility to register node "n" with PhaseIdealLoop
2893 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
2894 _igvn.register_new_node_with_optimizer(n);
2895 loop->_body.push(n);
2896 if (n->is_CFG()) {
2897 set_loop(n, loop);
2898 set_idom(n, pred, ddepth);
2899 } else {
2900 set_ctrl(n, pred);
2901 }
2902 }
2903
2904 //------------------------------ proj_clone -------------------------------------
2905 // Utility to create an if-projection
2906 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2907 ProjNode* c = p->clone()->as_Proj();
2908 c->set_req(0, iff);
2909 return c;
2910 }
2911
2912 //------------------------------ short_circuit_if -------------------------------------
2913 // Force the iff control output to be the live_proj
2914 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2915 guarantee(live_proj != nullptr, "null projection");
2916 int proj_con = live_proj->_con;
2917 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2918 Node* con = intcon(proj_con);
2919 if (iff) {
2920 iff->set_req(1, con);
2921 }
2922 return con;
2923 }
2924
2925 //------------------------------ insert_if_before_proj -------------------------------------
2926 // Insert a new if before an if projection (* - new node)
2927 //
2928 // before
2929 // if(test)
2930 // / \
2931 // v v
2932 // other-proj proj (arg)
2933 //
2934 // after
2935 // if(test)
2936 // / \
2937 // / v
2938 // | * proj-clone
2939 // v |
2940 // other-proj v
2941 // * new_if(relop(cmp[IU](left,right)))
2942 // / \
2943 // v v
2944 // * new-proj proj
2945 // (returned)
2946 //
2947 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2948 IfNode* iff = proj->in(0)->as_If();
2949 IdealLoopTree *loop = get_loop(proj);
2950 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2951 uint ddepth = dom_depth(proj);
2952
2953 _igvn.rehash_node_delayed(iff);
2954 _igvn.rehash_node_delayed(proj);
2955
2956 proj->set_req(0, nullptr); // temporary disconnect
2957 ProjNode* proj2 = proj_clone(proj, iff);
2958 register_node(proj2, loop, iff, ddepth);
2959
2960 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2961 register_node(cmp, loop, proj2, ddepth);
2962
2963 BoolNode* bol = new BoolNode(cmp, relop);
2964 register_node(bol, loop, proj2, ddepth);
2965
2966 int opcode = iff->Opcode();
2967 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2968 IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
2969 register_node(new_if, loop, proj2, ddepth);
2970
2971 proj->set_req(0, new_if); // reattach
2972 set_idom(proj, new_if, ddepth);
2973
2974 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2975 guarantee(new_exit != nullptr, "null exit node");
2976 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2977
2978 return new_exit;
2979 }
2980
2981 //------------------------------ insert_region_before_proj -------------------------------------
2982 // Insert a region before an if projection (* - new node)
2983 //
2984 // before
2985 // if(test)
2986 // / |
2987 // v |
2988 // proj v
2989 // other-proj
2990 //
2991 // after
2992 // if(test)
2993 // / |
2994 // v |
2995 // * proj-clone v
2996 // | other-proj
2997 // v
2998 // * new-region
2999 // |
3000 // v
3001 // * dum_if
3002 // / \
3003 // v \
3004 // * dum-proj v
3005 // proj
3006 //
3007 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3008 IfNode* iff = proj->in(0)->as_If();
3009 IdealLoopTree *loop = get_loop(proj);
3010 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3011 uint ddepth = dom_depth(proj);
3012
3013 _igvn.rehash_node_delayed(iff);
3014 _igvn.rehash_node_delayed(proj);
3015
3016 proj->set_req(0, nullptr); // temporary disconnect
3017 ProjNode* proj2 = proj_clone(proj, iff);
3018 register_node(proj2, loop, iff, ddepth);
3019
3020 RegionNode* reg = new RegionNode(2);
3021 reg->set_req(1, proj2);
3022 register_node(reg, loop, iff, ddepth);
3023
3024 IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3025 register_node(dum_if, loop, reg, ddepth);
3026
3027 proj->set_req(0, dum_if); // reattach
3028 set_idom(proj, dum_if, ddepth);
3029
3030 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3031 register_node(dum_proj, loop, dum_if, ddepth);
3032
3033 return reg;
3034 }
3035
3036 // Idea
3037 // ----
3038 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3039 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3040 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3041 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3042 // test alone instead:
3043 //
3044 // Before Partial Peeling:
3045 // Loop:
3046 // <peeled section>
3047 // Split off signed loop exit test
3048 // <-- CUT HERE -->
3049 // Unchanged unsigned loop exit test
3050 // <rest of unpeeled section>
3051 // goto Loop
3052 //
3053 // After Partial Peeling:
3054 // <cloned peeled section>
3055 // Cloned split off signed loop exit test
3056 // Loop:
3057 // Unchanged unsigned loop exit test
3058 // <rest of unpeeled section>
3059 // <peeled section>
3060 // Split off signed loop exit test
3061 // goto Loop
3062 //
3063 // Details
3064 // -------
3065 // Before:
3066 // if (i <u limit) Unsigned loop exit condition
3067 // / |
3068 // v v
3069 // exit-proj stay-in-loop-proj
3070 //
3071 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3072 // before the CmpU on the stay-in-loop path and keep both tests:
3073 //
3074 // if (i <u limit) Signed loop exit test
3075 // / |
3076 // / if (i <u limit) Unsigned loop exit test
3077 // / / |
3078 // v v v
3079 // exit-region stay-in-loop-proj
3080 //
3081 // Implementation
3082 // --------------
3083 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3084 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3085 // exit tests is preserved, and their loop nesting is correct.
3086 //
3087 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3088 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3089 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3090 //
3091 // if (stay-in-loop-const) Killed original unsigned loop exit test
3092 // / |
3093 // / v
3094 // / if (i < limit) Split off signed loop exit test
3095 // / / |
3096 // / / v
3097 // / / if (i <u limit) Cloned unsigned loop exit test
3098 // / / / |
3099 // v v v |
3100 // exit-region |
3101 // | |
3102 // dummy-if |
3103 // / | |
3104 // dead | |
3105 // v v
3106 // exit-proj stay-in-loop-proj
3107 //
3108 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3109 // loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3110 //
3111 // Requirements
3112 // ------------
3113 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3114 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3115 // Otherwise, we need to bail out (see comments in the code below).
3116 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3117 const bool Signed = true;
3118 const bool Unsigned = false;
3119
3120 BoolNode* bol = if_cmpu->in(1)->as_Bool();
3121 if (bol->_test._test != BoolTest::lt) {
3122 return nullptr;
3123 }
3124 CmpNode* cmpu = bol->in(1)->as_Cmp();
3125 assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3126
3127 int stride = stride_of_possible_iv(if_cmpu);
3128 if (stride == 0) {
3129 return nullptr;
3130 }
3131
3132 Node* lp_proj = stay_in_loop(if_cmpu, loop);
3133 guarantee(lp_proj != nullptr, "null loop node");
3134
3135 ProjNode* lp_continue = lp_proj->as_Proj();
3136 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3137 if (!lp_exit->is_IfFalse()) {
3138 // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3139 // We therefore can't add a single exit condition.
3140 return nullptr;
3141 }
3142 // The unsigned loop exit condition is
3143 // !(i <u limit)
3144 // = i >=u limit
3145 //
3146 // First, we note that for any x for which
3147 // 0 <= x <= INT_MAX
3148 // we can convert x to an unsigned int and still get the same guarantee:
3149 // 0 <= (uint) x <= INT_MAX = (uint) INT_MAX
3150 // 0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX (LEMMA)
3151 //
3152 // With that in mind, if
3153 // limit >= 0 (COND)
3154 // then the unsigned loop exit condition
3155 // i >=u limit (ULE)
3156 // is equivalent to
3157 // i < 0 || i >= limit (SLE-full)
3158 // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3159 // (uint) i >=u MAX_INT >= limit >= 0
3160 // or otherwise
3161 // i >= limit >= 0
3162 // holds due to (LEMMA).
3163 //
3164 // For completeness, a counterexample with limit < 0:
3165 // Assume i = -3 and limit = -2:
3166 // i < 0
3167 // -2 < 0
3168 // is true and thus also "i < 0 || i >= limit". But
3169 // i >=u limit
3170 // -3 >=u -2
3171 // is false.
3172 Node* limit = cmpu->in(2);
3173 const TypeInt* type_limit = _igvn.type(limit)->is_int();
3174 if (type_limit->_lo < 0) {
3175 return nullptr;
3176 }
3177
3178 // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3179 // stride < 0:
3180 // i < 0 (SLE = SLE-negative)
3181 // stride > 0:
3182 // i >= limit (SLE = SLE-positive)
3183 // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3184 //
3185 // Loop:
3186 // <peeled section>
3187 // i >= limit (SLE-positive)
3188 // <-- CUT HERE -->
3189 // i >=u limit (ULE)
3190 // <rest of unpeeled section>
3191 // goto Loop
3192 //
3193 // We exit the loop if:
3194 // (SLE) is true OR (ULE) is true
3195 // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3196 // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3197 // (SLE) IMPLIES (ULE)
3198 // This indeed holds when (COND) is given:
3199 // - stride > 0:
3200 // i >= limit // (SLE = SLE-positive)
3201 // i >= limit >= 0 // (COND)
3202 // i >=u limit >= 0 // (LEMMA)
3203 // which is the unsigned loop exit condition (ULE).
3204 // - stride < 0:
3205 // i < 0 // (SLE = SLE-negative)
3206 // (uint) i >u MAX_INT // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3207 // MAX_INT >= limit >= 0 // (COND)
3208 // MAX_INT >=u limit >= 0 // (LEMMA)
3209 // and thus from (NEG) and (LEMMA):
3210 // i >=u limit
3211 // which is the unsigned loop exit condition (ULE).
3212 //
3213 //
3214 // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3215 // <cloned peeled section>
3216 // i >= limit (SLE-positive)
3217 // Loop:
3218 // i >=u limit (ULE)
3219 // <rest of unpeeled section>
3220 // <peeled section>
3221 // i >= limit (SLE-positive)
3222 // goto Loop
3223 Node* rhs_cmpi;
3224 if (stride > 0) {
3225 rhs_cmpi = limit; // For i >= limit
3226 } else {
3227 rhs_cmpi = makecon(TypeInt::ZERO); // For i < 0
3228 }
3229 // Create a new region on the exit path
3230 RegionNode* reg = insert_region_before_proj(lp_exit);
3231 guarantee(reg != nullptr, "null region node");
3232
3233 // Clone the if-cmpu-true-false using a signed compare
3234 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3235 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3236 reg->add_req(cmpi_exit);
3237
3238 // Clone the if-cmpu-true-false
3239 BoolTest::mask rel_u = bol->_test._test;
3240 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3241 reg->add_req(cmpu_exit);
3242
3243 // Force original if to stay in loop.
3244 short_circuit_if(if_cmpu, lp_continue);
3245
3246 return cmpi_exit->in(0)->as_If();
3247 }
3248
3249 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3250 // Remove a previously inserted signed compare loop exit.
3251 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3252 Node* lp_proj = stay_in_loop(if_cmp, loop);
3253 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3254 stay_in_loop(lp_proj, loop)->is_If() &&
3255 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3256 Node* con = makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3257 if_cmp->set_req(1, con);
3258 }
3259
3260 //------------------------------ scheduled_nodelist -------------------------------------
3261 // Create a post order schedule of nodes that are in the
3262 // "member" set. The list is returned in "sched".
3263 // The first node in "sched" is the loop head, followed by
3264 // nodes which have no inputs in the "member" set, and then
3265 // followed by the nodes that have an immediate input dependence
3266 // on a node in "sched".
3267 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3268
3269 assert(member.test(loop->_head->_idx), "loop head must be in member set");
3270 VectorSet visited;
3271 Node_Stack nstack(loop->_body.size());
3272
3273 Node* n = loop->_head; // top of stack is cached in "n"
3274 uint idx = 0;
3275 visited.set(n->_idx);
3276
3277 // Initially push all with no inputs from within member set
3278 for(uint i = 0; i < loop->_body.size(); i++ ) {
3279 Node *elt = loop->_body.at(i);
3280 if (member.test(elt->_idx)) {
3281 bool found = false;
3282 for (uint j = 0; j < elt->req(); j++) {
3283 Node* def = elt->in(j);
3284 if (def && member.test(def->_idx) && def != elt) {
3285 found = true;
3286 break;
3287 }
3288 }
3289 if (!found && elt != loop->_head) {
3290 nstack.push(n, idx);
3291 n = elt;
3292 assert(!visited.test(n->_idx), "not seen yet");
3293 visited.set(n->_idx);
3294 }
3295 }
3296 }
3297
3298 // traverse out's that are in the member set
3299 while (true) {
3300 if (idx < n->outcnt()) {
3301 Node* use = n->raw_out(idx);
3302 idx++;
3303 if (!visited.test_set(use->_idx)) {
3304 if (member.test(use->_idx)) {
3305 nstack.push(n, idx);
3306 n = use;
3307 idx = 0;
3308 }
3309 }
3310 } else {
3311 // All outputs processed
3312 sched.push(n);
3313 if (nstack.is_empty()) break;
3314 n = nstack.node();
3315 idx = nstack.index();
3316 nstack.pop();
3317 }
3318 }
3319 }
3320
3321
3322 //------------------------------ has_use_in_set -------------------------------------
3323 // Has a use in the vector set
3324 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3325 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3326 Node* use = n->fast_out(j);
3327 if (vset.test(use->_idx)) {
3328 return true;
3329 }
3330 }
3331 return false;
3332 }
3333
3334
3335 //------------------------------ has_use_internal_to_set -------------------------------------
3336 // Has use internal to the vector set (ie. not in a phi at the loop head)
3337 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3338 Node* head = loop->_head;
3339 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3340 Node* use = n->fast_out(j);
3341 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3342 return true;
3343 }
3344 }
3345 return false;
3346 }
3347
3348
3349 //------------------------------ clone_for_use_outside_loop -------------------------------------
3350 // clone "n" for uses that are outside of loop
3351 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3352 int cloned = 0;
3353 assert(worklist.size() == 0, "should be empty");
3354 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3355 Node* use = n->fast_out(j);
3356 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3357 worklist.push(use);
3358 }
3359 }
3360
3361 if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3362 "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3363 return -1;
3364 }
3365
3366 while( worklist.size() ) {
3367 Node *use = worklist.pop();
3368 if (!has_node(use) || use->in(0) == C->top()) continue;
3369 uint j;
3370 for (j = 0; j < use->req(); j++) {
3371 if (use->in(j) == n) break;
3372 }
3373 assert(j < use->req(), "must be there");
3374
3375 // clone "n" and insert it between the inputs of "n" and the use outside the loop
3376 Node* n_clone = n->clone();
3377 _igvn.replace_input_of(use, j, n_clone);
3378 cloned++;
3379 Node* use_c;
3380 if (!use->is_Phi()) {
3381 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3382 } else {
3383 // Use in a phi is considered a use in the associated predecessor block
3384 use_c = use->in(0)->in(j);
3385 }
3386 set_ctrl(n_clone, use_c);
3387 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3388 get_loop(use_c)->_body.push(n_clone);
3389 _igvn.register_new_node_with_optimizer(n_clone);
3390 #ifndef PRODUCT
3391 if (TracePartialPeeling) {
3392 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3393 }
3394 #endif
3395 }
3396 return cloned;
3397 }
3398
3399
3400 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3401 // clone "n" for special uses that are in the not_peeled region.
3402 // If these def-uses occur in separate blocks, the code generator
3403 // marks the method as not compilable. For example, if a "BoolNode"
3404 // is in a different basic block than the "IfNode" that uses it, then
3405 // the compilation is aborted in the code generator.
3406 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3407 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3408 if (n->is_Phi() || n->is_Load()) {
3409 return;
3410 }
3411 assert(worklist.size() == 0, "should be empty");
3412 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3413 Node* use = n->fast_out(j);
3414 if ( not_peel.test(use->_idx) &&
3415 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
3416 use->in(1) == n) {
3417 worklist.push(use);
3418 }
3419 }
3420 if (worklist.size() > 0) {
3421 // clone "n" and insert it between inputs of "n" and the use
3422 Node* n_clone = n->clone();
3423 loop->_body.push(n_clone);
3424 _igvn.register_new_node_with_optimizer(n_clone);
3425 set_ctrl(n_clone, get_ctrl(n));
3426 sink_list.push(n_clone);
3427 not_peel.set(n_clone->_idx);
3428 #ifndef PRODUCT
3429 if (TracePartialPeeling) {
3430 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3431 }
3432 #endif
3433 while( worklist.size() ) {
3434 Node *use = worklist.pop();
3435 _igvn.rehash_node_delayed(use);
3436 for (uint j = 1; j < use->req(); j++) {
3437 if (use->in(j) == n) {
3438 use->set_req(j, n_clone);
3439 }
3440 }
3441 }
3442 }
3443 }
3444
3445
3446 //------------------------------ insert_phi_for_loop -------------------------------------
3447 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3448 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3449 Node *phi = PhiNode::make(lp, back_edge_val);
3450 phi->set_req(LoopNode::EntryControl, lp_entry_val);
3451 // Use existing phi if it already exists
3452 Node *hit = _igvn.hash_find_insert(phi);
3453 if( hit == nullptr ) {
3454 _igvn.register_new_node_with_optimizer(phi);
3455 set_ctrl(phi, lp);
3456 } else {
3457 // Remove the new phi from the graph and use the hit
3458 _igvn.remove_dead_node(phi);
3459 phi = hit;
3460 }
3461 _igvn.replace_input_of(use, idx, phi);
3462 }
3463
3464 #ifdef ASSERT
3465 //------------------------------ is_valid_loop_partition -------------------------------------
3466 // Validate the loop partition sets: peel and not_peel
3467 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3468 VectorSet& not_peel ) {
3469 uint i;
3470 // Check that peel_list entries are in the peel set
3471 for (i = 0; i < peel_list.size(); i++) {
3472 if (!peel.test(peel_list.at(i)->_idx)) {
3473 return false;
3474 }
3475 }
3476 // Check at loop members are in one of peel set or not_peel set
3477 for (i = 0; i < loop->_body.size(); i++ ) {
3478 Node *def = loop->_body.at(i);
3479 uint di = def->_idx;
3480 // Check that peel set elements are in peel_list
3481 if (peel.test(di)) {
3482 if (not_peel.test(di)) {
3483 return false;
3484 }
3485 // Must be in peel_list also
3486 bool found = false;
3487 for (uint j = 0; j < peel_list.size(); j++) {
3488 if (peel_list.at(j)->_idx == di) {
3489 found = true;
3490 break;
3491 }
3492 }
3493 if (!found) {
3494 return false;
3495 }
3496 } else if (not_peel.test(di)) {
3497 if (peel.test(di)) {
3498 return false;
3499 }
3500 } else {
3501 return false;
3502 }
3503 }
3504 return true;
3505 }
3506
3507 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3508 // Ensure a use outside of loop is of the right form
3509 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3510 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3511 return (use->is_Phi() &&
3512 use_c->is_Region() && use_c->req() == 3 &&
3513 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3514 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3515 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3516 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3517 }
3518
3519 //------------------------------ is_valid_clone_loop_form -------------------------------------
3520 // Ensure that all uses outside of loop are of the right form
3521 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3522 uint orig_exit_idx, uint clone_exit_idx) {
3523 uint len = peel_list.size();
3524 for (uint i = 0; i < len; i++) {
3525 Node *def = peel_list.at(i);
3526
3527 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3528 Node *use = def->fast_out(j);
3529 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3530 if (!loop->is_member(get_loop(use_c))) {
3531 // use is not in the loop, check for correct structure
3532 if (use->in(0) == def) {
3533 // Okay
3534 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3535 return false;
3536 }
3537 }
3538 }
3539 }
3540 return true;
3541 }
3542 #endif
3543
3544 //------------------------------ partial_peel -------------------------------------
3545 // Partially peel (aka loop rotation) the top portion of a loop (called
3546 // the peel section below) by cloning it and placing one copy just before
3547 // the new loop head and the other copy at the bottom of the new loop.
3548 //
3549 // before after where it came from
3550 //
3551 // stmt1 stmt1
3552 // loop: stmt2 clone
3553 // stmt2 if condA goto exitA clone
3554 // if condA goto exitA new_loop: new
3555 // stmt3 stmt3 clone
3556 // if !condB goto loop if condB goto exitB clone
3557 // exitB: stmt2 orig
3558 // stmt4 if !condA goto new_loop orig
3559 // exitA: goto exitA
3560 // exitB:
3561 // stmt4
3562 // exitA:
3563 //
3564 // Step 1: find the cut point: an exit test on probable
3565 // induction variable.
3566 // Step 2: schedule (with cloning) operations in the peel
3567 // section that can be executed after the cut into
3568 // the section that is not peeled. This may need
3569 // to clone operations into exit blocks. For
3570 // instance, a reference to A[i] in the not-peel
3571 // section and a reference to B[i] in an exit block
3572 // may cause a left-shift of i by 2 to be placed
3573 // in the peel block. This step will clone the left
3574 // shift into the exit block and sink the left shift
3575 // from the peel to the not-peel section.
3576 // Step 3: clone the loop, retarget the control, and insert
3577 // phis for values that are live across the new loop
3578 // head. This is very dependent on the graph structure
3579 // from clone_loop. It creates region nodes for
3580 // exit control and associated phi nodes for values
3581 // flow out of the loop through that exit. The region
3582 // node is dominated by the clone's control projection.
3583 // So the clone's peel section is placed before the
3584 // new loop head, and the clone's not-peel section is
3585 // forms the top part of the new loop. The original
3586 // peel section forms the tail of the new loop.
3587 // Step 4: update the dominator tree and recompute the
3588 // dominator depth.
3589 //
3590 // orig
3591 //
3592 // stmt1
3593 // |
3594 // v
3595 // predicates
3596 // |
3597 // v
3598 // loop<----+
3599 // | |
3600 // stmt2 |
3601 // | |
3602 // v |
3603 // ifA |
3604 // / | |
3605 // v v |
3606 // false true ^ <-- last_peel
3607 // / | |
3608 // / ===|==cut |
3609 // / stmt3 | <-- first_not_peel
3610 // / | |
3611 // | v |
3612 // v ifB |
3613 // exitA: / \ |
3614 // / \ |
3615 // v v |
3616 // false true |
3617 // / \ |
3618 // / ----+
3619 // |
3620 // v
3621 // exitB:
3622 // stmt4
3623 //
3624 //
3625 // after clone loop
3626 //
3627 // stmt1
3628 // |
3629 // v
3630 // predicates
3631 // / \
3632 // clone / \ orig
3633 // / \
3634 // / \
3635 // v v
3636 // +---->loop loop<----+
3637 // | | | |
3638 // | stmt2 stmt2 |
3639 // | | | |
3640 // | v v |
3641 // | ifA ifA |
3642 // | | \ / | |
3643 // | v v v v |
3644 // ^ true false false true ^ <-- last_peel
3645 // | | ^ \ / | |
3646 // | cut==|== \ \ / ===|==cut |
3647 // | stmt3 \ \ / stmt3 | <-- first_not_peel
3648 // | | dom | | | |
3649 // | v \ 1v v2 v |
3650 // | ifB regionA ifB |
3651 // | / \ | / \ |
3652 // | / \ v / \ |
3653 // | v v exitA: v v |
3654 // | true false false true |
3655 // | / ^ \ / \ |
3656 // +---- \ \ / ----+
3657 // dom \ /
3658 // \ 1v v2
3659 // regionB
3660 // |
3661 // v
3662 // exitB:
3663 // stmt4
3664 //
3665 //
3666 // after partial peel
3667 //
3668 // stmt1
3669 // |
3670 // v
3671 // predicates
3672 // /
3673 // clone / orig
3674 // / TOP
3675 // / \
3676 // v v
3677 // TOP->loop loop----+
3678 // | | |
3679 // stmt2 stmt2 |
3680 // | | |
3681 // v v |
3682 // ifA ifA |
3683 // | \ / | |
3684 // v v v v |
3685 // true false false true | <-- last_peel
3686 // | ^ \ / +------|---+
3687 // +->newloop \ \ / === ==cut | |
3688 // | stmt3 \ \ / TOP | |
3689 // | | dom | | stmt3 | | <-- first_not_peel
3690 // | v \ 1v v2 v | |
3691 // | ifB regionA ifB ^ v
3692 // | / \ | / \ | |
3693 // | / \ v / \ | |
3694 // | v v exitA: v v | |
3695 // | true false false true | |
3696 // | / ^ \ / \ | |
3697 // | | \ \ / v | |
3698 // | | dom \ / TOP | |
3699 // | | \ 1v v2 | |
3700 // ^ v regionB | |
3701 // | | | | |
3702 // | | v ^ v
3703 // | | exitB: | |
3704 // | | stmt4 | |
3705 // | +------------>-----------------+ |
3706 // | |
3707 // +-----------------<---------------------+
3708 //
3709 //
3710 // final graph
3711 //
3712 // stmt1
3713 // |
3714 // v
3715 // predicates
3716 // |
3717 // v
3718 // stmt2 clone
3719 // |
3720 // v
3721 // ........> ifA clone
3722 // : / |
3723 // dom / |
3724 // : v v
3725 // : false true
3726 // : | |
3727 // : | v
3728 // : | newloop<-----+
3729 // : | | |
3730 // : | stmt3 clone |
3731 // : | | |
3732 // : | v |
3733 // : | ifB |
3734 // : | / \ |
3735 // : | v v |
3736 // : | false true |
3737 // : | | | |
3738 // : | v stmt2 |
3739 // : | exitB: | |
3740 // : | stmt4 v |
3741 // : | ifA orig |
3742 // : | / \ |
3743 // : | / \ |
3744 // : | v v |
3745 // : | false true |
3746 // : | / \ |
3747 // : v v -----+
3748 // RegionA
3749 // |
3750 // v
3751 // exitA
3752 //
3753 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3754
3755 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3756 if (!loop->_head->is_Loop()) {
3757 return false;
3758 }
3759 LoopNode *head = loop->_head->as_Loop();
3760
3761 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3762 return false;
3763 }
3764
3765 // Check for complex exit control
3766 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3767 Node *n = loop->_body.at(ii);
3768 int opc = n->Opcode();
3769 if (n->is_Call() ||
3770 opc == Op_Catch ||
3771 opc == Op_CatchProj ||
3772 opc == Op_Jump ||
3773 opc == Op_JumpProj) {
3774 #ifndef PRODUCT
3775 if (TracePartialPeeling) {
3776 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3777 }
3778 #endif
3779 return false;
3780 }
3781 }
3782
3783 int dd = dom_depth(head);
3784
3785 // Step 1: find cut point
3786
3787 // Walk up dominators to loop head looking for first loop exit
3788 // which is executed on every path thru loop.
3789 IfNode *peel_if = nullptr;
3790 IfNode *peel_if_cmpu = nullptr;
3791
3792 Node *iff = loop->tail();
3793 while (iff != head) {
3794 if (iff->is_If()) {
3795 Node *ctrl = get_ctrl(iff->in(1));
3796 if (ctrl->is_top()) return false; // Dead test on live IF.
3797 // If loop-varying exit-test, check for induction variable
3798 if (loop->is_member(get_loop(ctrl)) &&
3799 loop->is_loop_exit(iff) &&
3800 is_possible_iv_test(iff)) {
3801 Node* cmp = iff->in(1)->in(1);
3802 if (cmp->Opcode() == Op_CmpI) {
3803 peel_if = iff->as_If();
3804 } else {
3805 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3806 peel_if_cmpu = iff->as_If();
3807 }
3808 }
3809 }
3810 iff = idom(iff);
3811 }
3812
3813 // Prefer signed compare over unsigned compare.
3814 IfNode* new_peel_if = nullptr;
3815 if (peel_if == nullptr) {
3816 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
3817 return false; // No peel point found
3818 }
3819 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3820 if (new_peel_if == nullptr) {
3821 return false; // No peel point found
3822 }
3823 peel_if = new_peel_if;
3824 }
3825 Node* last_peel = stay_in_loop(peel_if, loop);
3826 Node* first_not_peeled = stay_in_loop(last_peel, loop);
3827 if (first_not_peeled == nullptr || first_not_peeled == head) {
3828 return false;
3829 }
3830
3831 #ifndef PRODUCT
3832 if (TraceLoopOpts) {
3833 tty->print("PartialPeel ");
3834 loop->dump_head();
3835 }
3836
3837 if (TracePartialPeeling) {
3838 tty->print_cr("before partial peel one iteration");
3839 Node_List wl;
3840 Node* t = head->in(2);
3841 while (true) {
3842 wl.push(t);
3843 if (t == head) break;
3844 t = idom(t);
3845 }
3846 while (wl.size() > 0) {
3847 Node* tt = wl.pop();
3848 tt->dump();
3849 if (tt == last_peel) tty->print_cr("-- cut --");
3850 }
3851 }
3852 #endif
3853
3854 C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
3855
3856 VectorSet peel;
3857 VectorSet not_peel;
3858 Node_List peel_list;
3859 Node_List worklist;
3860 Node_List sink_list;
3861
3862 uint estimate = loop->est_loop_clone_sz(1);
3863 if (exceeding_node_budget(estimate)) {
3864 return false;
3865 }
3866
3867 // Set of cfg nodes to peel are those that are executable from
3868 // the head through last_peel.
3869 assert(worklist.size() == 0, "should be empty");
3870 worklist.push(head);
3871 peel.set(head->_idx);
3872 while (worklist.size() > 0) {
3873 Node *n = worklist.pop();
3874 if (n != last_peel) {
3875 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3876 Node* use = n->fast_out(j);
3877 if (use->is_CFG() &&
3878 loop->is_member(get_loop(use)) &&
3879 !peel.test_set(use->_idx)) {
3880 worklist.push(use);
3881 }
3882 }
3883 }
3884 }
3885
3886 // Set of non-cfg nodes to peel are those that are control
3887 // dependent on the cfg nodes.
3888 for (uint i = 0; i < loop->_body.size(); i++) {
3889 Node *n = loop->_body.at(i);
3890 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3891 if (peel.test(n_c->_idx)) {
3892 peel.set(n->_idx);
3893 } else {
3894 not_peel.set(n->_idx);
3895 }
3896 }
3897
3898 // Step 2: move operations from the peeled section down into the
3899 // not-peeled section
3900
3901 // Get a post order schedule of nodes in the peel region
3902 // Result in right-most operand.
3903 scheduled_nodelist(loop, peel, peel_list);
3904
3905 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3906
3907 // For future check for too many new phis
3908 uint old_phi_cnt = 0;
3909 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3910 Node* use = head->fast_out(j);
3911 if (use->is_Phi()) old_phi_cnt++;
3912 }
3913
3914 #ifndef PRODUCT
3915 if (TracePartialPeeling) {
3916 tty->print_cr("\npeeled list");
3917 }
3918 #endif
3919
3920 // Evacuate nodes in peel region into the not_peeled region if possible
3921 bool too_many_clones = false;
3922 uint new_phi_cnt = 0;
3923 uint cloned_for_outside_use = 0;
3924 for (uint i = 0; i < peel_list.size();) {
3925 Node* n = peel_list.at(i);
3926 #ifndef PRODUCT
3927 if (TracePartialPeeling) n->dump();
3928 #endif
3929 bool incr = true;
3930 if (!n->is_CFG()) {
3931 if (has_use_in_set(n, not_peel)) {
3932 // If not used internal to the peeled region,
3933 // move "n" from peeled to not_peeled region.
3934 if (!has_use_internal_to_set(n, peel, loop)) {
3935 // if not pinned and not a load (which maybe anti-dependent on a store)
3936 // and not a CMove (Matcher expects only bool->cmove).
3937 if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
3938 int new_clones = clone_for_use_outside_loop(loop, n, worklist);
3939 if (C->failing()) return false;
3940 if (new_clones == -1) {
3941 too_many_clones = true;
3942 break;
3943 }
3944 cloned_for_outside_use += new_clones;
3945 sink_list.push(n);
3946 peel.remove(n->_idx);
3947 not_peel.set(n->_idx);
3948 peel_list.remove(i);
3949 incr = false;
3950 #ifndef PRODUCT
3951 if (TracePartialPeeling) {
3952 tty->print_cr("sink to not_peeled region: %d newbb: %d",
3953 n->_idx, get_ctrl(n)->_idx);
3954 }
3955 #endif
3956 }
3957 } else {
3958 // Otherwise check for special def-use cases that span
3959 // the peel/not_peel boundary such as bool->if
3960 clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3961 new_phi_cnt++;
3962 }
3963 }
3964 }
3965 if (incr) i++;
3966 }
3967
3968 estimate += cloned_for_outside_use + new_phi_cnt;
3969 bool exceed_node_budget = !may_require_nodes(estimate);
3970 bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3971
3972 if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
3973 #ifndef PRODUCT
3974 if (TracePartialPeeling && exceed_phi_limit) {
3975 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
3976 new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
3977 }
3978 #endif
3979 if (new_peel_if != nullptr) {
3980 remove_cmpi_loop_exit(new_peel_if, loop);
3981 }
3982 // Inhibit more partial peeling on this loop
3983 assert(!head->is_partial_peel_loop(), "not partial peeled");
3984 head->mark_partial_peel_failed();
3985 if (cloned_for_outside_use > 0) {
3986 // Terminate this round of loop opts because
3987 // the graph outside this loop was changed.
3988 C->set_major_progress();
3989 return true;
3990 }
3991 return false;
3992 }
3993
3994 // Step 3: clone loop, retarget control, and insert new phis
3995
3996 // Create new loop head for new phis and to hang
3997 // the nodes being moved (sinked) from the peel region.
3998 LoopNode* new_head = new LoopNode(last_peel, last_peel);
3999 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
4000 _igvn.register_new_node_with_optimizer(new_head);
4001 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
4002 _igvn.replace_input_of(first_not_peeled, 0, new_head);
4003 set_loop(new_head, loop);
4004 loop->_body.push(new_head);
4005 not_peel.set(new_head->_idx);
4006 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
4007 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
4008
4009 while (sink_list.size() > 0) {
4010 Node* n = sink_list.pop();
4011 set_ctrl(n, new_head);
4012 }
4013
4014 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4015
4016 clone_loop(loop, old_new, dd, IgnoreStripMined);
4017
4018 const uint clone_exit_idx = 1;
4019 const uint orig_exit_idx = 2;
4020 assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4021
4022 Node* head_clone = old_new[head->_idx];
4023 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
4024 Node* orig_tail_clone = head_clone->in(2);
4025
4026 // Add phi if "def" node is in peel set and "use" is not
4027
4028 for (uint i = 0; i < peel_list.size(); i++) {
4029 Node *def = peel_list.at(i);
4030 if (!def->is_CFG()) {
4031 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4032 Node *use = def->fast_out(j);
4033 if (has_node(use) && use->in(0) != C->top() &&
4034 (!peel.test(use->_idx) ||
4035 (use->is_Phi() && use->in(0) == head)) ) {
4036 worklist.push(use);
4037 }
4038 }
4039 while( worklist.size() ) {
4040 Node *use = worklist.pop();
4041 for (uint j = 1; j < use->req(); j++) {
4042 Node* n = use->in(j);
4043 if (n == def) {
4044
4045 // "def" is in peel set, "use" is not in peel set
4046 // or "use" is in the entry boundary (a phi) of the peel set
4047
4048 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4049
4050 if ( loop->is_member(get_loop( use_c )) ) {
4051 // use is in loop
4052 if (old_new[use->_idx] != nullptr) { // null for dead code
4053 Node* use_clone = old_new[use->_idx];
4054 _igvn.replace_input_of(use, j, C->top());
4055 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4056 }
4057 } else {
4058 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4059 // use is not in the loop, check if the live range includes the cut
4060 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4061 if (not_peel.test(lp_if->_idx)) {
4062 assert(j == orig_exit_idx, "use from original loop");
4063 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4064 }
4065 }
4066 }
4067 }
4068 }
4069 }
4070 }
4071
4072 // Step 3b: retarget control
4073
4074 // Redirect control to the new loop head if a cloned node in
4075 // the not_peeled region has control that points into the peeled region.
4076 // This necessary because the cloned peeled region will be outside
4077 // the loop.
4078 // from to
4079 // cloned-peeled <---+
4080 // new_head_clone: | <--+
4081 // cloned-not_peeled in(0) in(0)
4082 // orig-peeled
4083
4084 for (uint i = 0; i < loop->_body.size(); i++) {
4085 Node *n = loop->_body.at(i);
4086 if (!n->is_CFG() && n->in(0) != nullptr &&
4087 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4088 Node* n_clone = old_new[n->_idx];
4089 if (n_clone->depends_only_on_test()) {
4090 // Pin array access nodes: control is updated here to the loop head. If, after some transformations, the
4091 // backedge is removed, an array load could become dependent on a condition that's not a range check for that
4092 // access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
4093 // floating above its range check.
4094 Node* pinned_clone = n_clone->pin_array_access_node();
4095 if (pinned_clone != nullptr) {
4096 register_new_node_with_ctrl_of(pinned_clone, n_clone);
4097 old_new.map(n->_idx, pinned_clone);
4098 _igvn.replace_node(n_clone, pinned_clone);
4099 n_clone = pinned_clone;
4100 }
4101 }
4102 _igvn.replace_input_of(n_clone, 0, new_head_clone);
4103 }
4104 }
4105
4106 // Backedge of the surviving new_head (the clone) is original last_peel
4107 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4108
4109 // Cut first node in original not_peel set
4110 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
4111 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
4112 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
4113
4114 // Copy head_clone back-branch info to original head
4115 // and remove original head's loop entry and
4116 // clone head's back-branch
4117 _igvn.rehash_node_delayed(head); // Multiple edge updates
4118 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
4119 head->set_req(LoopNode::LoopBackControl, C->top());
4120 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4121
4122 // Similarly modify the phis
4123 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4124 Node* use = head->fast_out(k);
4125 if (use->is_Phi() && use->outcnt() > 0) {
4126 Node* use_clone = old_new[use->_idx];
4127 _igvn.rehash_node_delayed(use); // Multiple edge updates
4128 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
4129 use->set_req(LoopNode::LoopBackControl, C->top());
4130 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4131 }
4132 }
4133
4134 // Step 4: update dominator tree and dominator depth
4135
4136 set_idom(head, orig_tail_clone, dd);
4137 recompute_dom_depth();
4138
4139 // Inhibit more partial peeling on this loop
4140 new_head_clone->set_partial_peel_loop();
4141 C->set_major_progress();
4142 loop->record_for_igvn();
4143
4144 #ifndef PRODUCT
4145 if (TracePartialPeeling) {
4146 tty->print_cr("\nafter partial peel one iteration");
4147 Node_List wl;
4148 Node* t = last_peel;
4149 while (true) {
4150 wl.push(t);
4151 if (t == head_clone) break;
4152 t = idom(t);
4153 }
4154 while (wl.size() > 0) {
4155 Node* tt = wl.pop();
4156 if (tt == head) tty->print_cr("orig head");
4157 else if (tt == new_head_clone) tty->print_cr("new head");
4158 else if (tt == head_clone) tty->print_cr("clone head");
4159 tt->dump();
4160 }
4161 }
4162 #endif
4163
4164 C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4165
4166 return true;
4167 }
4168
4169 // Transform:
4170 //
4171 // loop<-----------------+
4172 // | |
4173 // stmt1 stmt2 .. stmtn |
4174 // | | | |
4175 // \ | / |
4176 // v v v |
4177 // region |
4178 // | |
4179 // shared_stmt |
4180 // | |
4181 // v |
4182 // if |
4183 // / \ |
4184 // | -----------+
4185 // v
4186 //
4187 // into:
4188 //
4189 // loop<-------------------+
4190 // | |
4191 // v |
4192 // +->loop |
4193 // | | |
4194 // | stmt1 stmt2 .. stmtn |
4195 // | | | | |
4196 // | | \ / |
4197 // | | v v |
4198 // | | region1 |
4199 // | | | |
4200 // | shared_stmt shared_stmt |
4201 // | | | |
4202 // | v v |
4203 // | if if |
4204 // | /\ / \ |
4205 // +-- | | -------+
4206 // \ /
4207 // v v
4208 // region2
4209 //
4210 // (region2 is shown to merge mirrored projections of the loop exit
4211 // ifs to make the diagram clearer but they really merge the same
4212 // projection)
4213 //
4214 // Conditions for this transformation to trigger:
4215 // - the path through stmt1 is frequent enough
4216 // - the inner loop will be turned into a counted loop after transformation
4217 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4218 if (!DuplicateBackedge) {
4219 return false;
4220 }
4221 assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4222 if (!loop->_head->is_Loop()) {
4223 return false;
4224 }
4225
4226 uint estimate = loop->est_loop_clone_sz(1);
4227 if (exceeding_node_budget(estimate)) {
4228 return false;
4229 }
4230
4231 LoopNode *head = loop->_head->as_Loop();
4232
4233 Node* region = nullptr;
4234 IfNode* exit_test = nullptr;
4235 uint inner;
4236 float f;
4237 if (StressDuplicateBackedge) {
4238 if (head->is_strip_mined()) {
4239 return false;
4240 }
4241 Node* c = head->in(LoopNode::LoopBackControl);
4242
4243 while (c != head) {
4244 if (c->is_Region()) {
4245 region = c;
4246 }
4247 c = idom(c);
4248 }
4249
4250 if (region == nullptr) {
4251 return false;
4252 }
4253
4254 inner = 1;
4255 } else {
4256 // Is the shape of the loop that of a counted loop...
4257 Node* back_control = loop_exit_control(head, loop);
4258 if (back_control == nullptr) {
4259 return false;
4260 }
4261
4262 BoolTest::mask bt = BoolTest::illegal;
4263 float cl_prob = 0;
4264 Node* incr = nullptr;
4265 Node* limit = nullptr;
4266 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4267 if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4268 return false;
4269 }
4270
4271 // With an extra phi for the candidate iv?
4272 // Or the region node is the loop head
4273 if (!incr->is_Phi() || incr->in(0) == head) {
4274 return false;
4275 }
4276
4277 PathFrequency pf(head, this);
4278 region = incr->in(0);
4279
4280 // Go over all paths for the extra phi's region and see if that
4281 // path is frequent enough and would match the expected iv shape
4282 // if the extra phi is removed
4283 inner = 0;
4284 for (uint i = 1; i < incr->req(); ++i) {
4285 Node* in = incr->in(i);
4286 Node* trunc1 = nullptr;
4287 Node* trunc2 = nullptr;
4288 const TypeInteger* iv_trunc_t = nullptr;
4289 Node* orig_in = in;
4290 if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4291 continue;
4292 }
4293 assert(in->Opcode() == Op_AddI, "wrong increment code");
4294 Node* xphi = nullptr;
4295 Node* stride = loop_iv_stride(in, loop, xphi);
4296
4297 if (stride == nullptr) {
4298 continue;
4299 }
4300
4301 PhiNode* phi = loop_iv_phi(xphi, nullptr, head, loop);
4302 if (phi == nullptr ||
4303 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4304 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4305 return false;
4306 }
4307
4308 f = pf.to(region->in(i));
4309 if (f > 0.5) {
4310 inner = i;
4311 break;
4312 }
4313 }
4314
4315 if (inner == 0) {
4316 return false;
4317 }
4318
4319 exit_test = back_control->in(0)->as_If();
4320 }
4321
4322 if (idom(region)->is_Catch()) {
4323 return false;
4324 }
4325
4326 // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4327 Unique_Node_List wq;
4328 wq.push(head->in(LoopNode::LoopBackControl));
4329 for (uint i = 0; i < wq.size(); i++) {
4330 Node* c = wq.at(i);
4331 assert(get_loop(c) == loop, "not in the right loop?");
4332 if (c->is_Region()) {
4333 if (c != region) {
4334 for (uint j = 1; j < c->req(); ++j) {
4335 wq.push(c->in(j));
4336 }
4337 }
4338 } else {
4339 wq.push(c->in(0));
4340 }
4341 assert(!is_strict_dominator(c, region), "shouldn't go above region");
4342 }
4343
4344 Node* region_dom = idom(region);
4345
4346 // Can't do the transformation if this would cause a membar pair to
4347 // be split
4348 for (uint i = 0; i < wq.size(); i++) {
4349 Node* c = wq.at(i);
4350 if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4351 assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4352 if (!wq.member(c->as_MemBar()->leading_membar())) {
4353 return false;
4354 }
4355 }
4356 }
4357
4358 // Collect data nodes that need to be clones as well
4359 int dd = dom_depth(head);
4360
4361 for (uint i = 0; i < loop->_body.size(); ++i) {
4362 Node* n = loop->_body.at(i);
4363 if (has_ctrl(n)) {
4364 Node* c = get_ctrl(n);
4365 if (wq.member(c)) {
4366 wq.push(n);
4367 }
4368 } else {
4369 set_idom(n, idom(n), dd);
4370 }
4371 }
4372
4373 // clone shared_stmt
4374 clone_loop_body(wq, old_new, nullptr);
4375
4376 Node* region_clone = old_new[region->_idx];
4377 region_clone->set_req(inner, C->top());
4378 set_idom(region, region->in(inner), dd);
4379
4380 // Prepare the outer loop
4381 Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4382 register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4383 _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4384 set_idom(head, outer_head, dd);
4385
4386 fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4387
4388 // Make one of the shared_stmt copies only reachable from stmt1, the
4389 // other only from stmt2..stmtn.
4390 Node* dom = nullptr;
4391 for (uint i = 1; i < region->req(); ++i) {
4392 if (i != inner) {
4393 _igvn.replace_input_of(region, i, C->top());
4394 }
4395 Node* in = region_clone->in(i);
4396 if (in->is_top()) {
4397 continue;
4398 }
4399 if (dom == nullptr) {
4400 dom = in;
4401 } else {
4402 dom = dom_lca(dom, in);
4403 }
4404 }
4405
4406 set_idom(region_clone, dom, dd);
4407
4408 // Set up the outer loop
4409 for (uint i = 0; i < head->outcnt(); i++) {
4410 Node* u = head->raw_out(i);
4411 if (u->is_Phi()) {
4412 Node* outer_phi = u->clone();
4413 outer_phi->set_req(0, outer_head);
4414 Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4415 if (backedge == nullptr) {
4416 backedge = u->in(LoopNode::LoopBackControl);
4417 }
4418 outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4419 register_new_node(outer_phi, outer_head);
4420 _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4421 }
4422 }
4423
4424 // create control and data nodes for out of loop uses (including region2)
4425 Node_List worklist;
4426 uint new_counter = C->unique();
4427 fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4428
4429 Node_List *split_if_set = nullptr;
4430 Node_List *split_bool_set = nullptr;
4431 Node_List *split_cex_set = nullptr;
4432 fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4433 split_if_set, split_bool_set, split_cex_set);
4434
4435 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4436
4437 if (exit_test != nullptr) {
4438 float cnt = exit_test->_fcnt;
4439 if (cnt != COUNT_UNKNOWN) {
4440 exit_test->_fcnt = cnt * f;
4441 old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4442 }
4443 }
4444
4445 C->set_major_progress();
4446
4447 return true;
4448 }
4449
4450 // AutoVectorize the loop: replace scalar ops with vector ops.
4451 PhaseIdealLoop::AutoVectorizeStatus
4452 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4453 // Counted loop only
4454 if (!lpt->is_counted()) {
4455 return AutoVectorizeStatus::Impossible;
4456 }
4457
4458 // Main-loop only
4459 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4460 if (!cl->is_main_loop()) {
4461 return AutoVectorizeStatus::Impossible;
4462 }
4463
4464 VLoop vloop(lpt, false);
4465 if (!vloop.check_preconditions()) {
4466 return AutoVectorizeStatus::TriedAndFailed;
4467 }
4468
4469 // Ensure the shared data is cleared before each use
4470 vshared.clear();
4471
4472 const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4473 if (!vloop_analyzer.success()) {
4474 return AutoVectorizeStatus::TriedAndFailed;
4475 }
4476
4477 SuperWord sw(vloop_analyzer);
4478 if (!sw.transform_loop()) {
4479 return AutoVectorizeStatus::TriedAndFailed;
4480 }
4481
4482 return AutoVectorizeStatus::Success;
4483 }
4484
4485 // Just before insert_pre_post_loops, we can multi-version the loop:
4486 //
4487 // multiversion_if
4488 // | |
4489 // fast_loop slow_loop
4490 //
4491 // In the fast_loop we can make speculative assumptions, and put the
4492 // conditions into the multiversion_if. If the conditions hold at runtime,
4493 // we enter the fast_loop, if the conditions fail, we take the slow_loop
4494 // instead which does not make any of the speculative assumptions.
4495 //
4496 // Note: we only multiversion the loop if the loop does not have any
4497 // auto vectorization check Predicate. If we have that predicate,
4498 // then we can simply add the speculative assumption checks to
4499 // that Predicate. This means we do not need to duplicate the
4500 // loop - we have a smaller graph and save compile time. Should
4501 // the conditions ever fail, then we deopt / trap at the Predicate
4502 // and recompile without that Predicate. At that point we will
4503 // multiversion the loop, so that we can still have speculative
4504 // runtime checks.
4505 //
4506 // We perform the multiversioning when the loop is still in its single
4507 // iteration form, even before we insert pre and post loops. This makes
4508 // the cloning much simpler. However, this means that both the fast
4509 // and the slow loop have to be optimized independently (adding pre
4510 // and post loops, unrolling the main loop, auto-vectorize etc.). And
4511 // we may end up not needing any speculative assumptions in the fast_loop
4512 // and then rejecting the slow_loop by constant folding the multiversion_if.
4513 //
4514 // Therefore, we "delay" the optimization of the slow_loop until we add
4515 // at least one speculative assumption for the fast_loop. If we never
4516 // add such a speculative runtime check, the OpaqueMultiversioningNode
4517 // of the multiversion_if constant folds to true after loop opts, and the
4518 // multiversion_if folds away the "delayed" slow_loop. If we add any
4519 // speculative assumption, then we notify the OpaqueMultiversioningNode
4520 // with "notify_slow_loop_that_it_can_resume_optimizations".
4521 //
4522 // Note: new runtime checks can be added to the multiversion_if with
4523 // PhaseIdealLoop::create_new_if_for_multiversion
4524 void PhaseIdealLoop::maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new) {
4525 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4526 LoopNode* outer_loop = cl->skip_strip_mined();
4527 Node* entry = outer_loop->in(LoopNode::EntryControl);
4528
4529 // Check we have multiversioning enabled, and are not already multiversioned.
4530 if (!LoopMultiversioning || cl->is_multiversion()) { return; }
4531
4532 // Check that we do not have a parse-predicate where we can add the runtime checks
4533 // during auto-vectorization.
4534 const Predicates predicates(entry);
4535 const PredicateBlock* predicate_block = predicates.auto_vectorization_check_block();
4536 if (predicate_block->has_parse_predicate()) { return; }
4537
4538 // Check node budget.
4539 uint estimate = lpt->est_loop_clone_sz(2);
4540 if (!may_require_nodes(estimate)) { return; }
4541
4542 do_multiversioning(lpt, old_new);
4543 }
4544
4545 // Returns true if the Reduction node is unordered.
4546 static bool is_unordered_reduction(Node* n) {
4547 return n->is_Reduction() && !n->as_Reduction()->requires_strict_order();
4548 }
4549
4550 // Having ReductionNodes in the loop is expensive. They need to recursively
4551 // fold together the vector values, for every vectorized loop iteration. If
4552 // we encounter the following pattern, we can vector accumulate the values
4553 // inside the loop, and only have a single UnorderedReduction after the loop.
4554 //
4555 // Note: UnorderedReduction represents a ReductionNode which does not require
4556 // calculating in strict order.
4557 //
4558 // CountedLoop init
4559 // | |
4560 // +------+ | +-----------------------+
4561 // | | | |
4562 // PhiNode (s) |
4563 // | |
4564 // | Vector |
4565 // | | |
4566 // UnorderedReduction (first_ur) |
4567 // | |
4568 // ... Vector |
4569 // | | |
4570 // UnorderedReduction (last_ur) |
4571 // | |
4572 // +---------------------+
4573 //
4574 // We patch the graph to look like this:
4575 //
4576 // CountedLoop identity_vector
4577 // | |
4578 // +-------+ | +---------------+
4579 // | | | |
4580 // PhiNode (v) |
4581 // | |
4582 // | Vector |
4583 // | | |
4584 // VectorAccumulator |
4585 // | |
4586 // ... Vector |
4587 // | | |
4588 // init VectorAccumulator |
4589 // | | | |
4590 // UnorderedReduction +-----------+
4591 //
4592 // We turned the scalar (s) Phi into a vectorized one (v). In the loop, we
4593 // use vector_accumulators, which do the same reductions, but only element
4594 // wise. This is a single operation per vector_accumulator, rather than many
4595 // for a UnorderedReduction. We can then reduce the last vector_accumulator
4596 // after the loop, and also reduce the init value into it.
4597 //
4598 // We can not do this with all reductions. Some reductions do not allow the
4599 // reordering of operations (for example float addition/multiplication require
4600 // strict order).
4601 void PhaseIdealLoop::move_unordered_reduction_out_of_loop(IdealLoopTree* loop) {
4602 assert(!C->major_progress() && loop->is_counted() && loop->is_innermost(), "sanity");
4603
4604 // Find all Phi nodes with an unordered Reduction on backedge.
4605 CountedLoopNode* cl = loop->_head->as_CountedLoop();
4606 for (DUIterator_Fast jmax, j = cl->fast_outs(jmax); j < jmax; j++) {
4607 Node* phi = cl->fast_out(j);
4608 // We have a phi with a single use, and an unordered Reduction on the backedge.
4609 if (!phi->is_Phi() || phi->outcnt() != 1 || !is_unordered_reduction(phi->in(2))) {
4610 continue;
4611 }
4612
4613 ReductionNode* last_ur = phi->in(2)->as_Reduction();
4614 assert(!last_ur->requires_strict_order(), "must be");
4615
4616 // Determine types
4617 const TypeVect* vec_t = last_ur->vect_type();
4618 uint vector_length = vec_t->length();
4619 BasicType bt = vec_t->element_basic_type();
4620
4621 // Convert opcode from vector-reduction -> scalar -> normal-vector-op
4622 const int sopc = VectorNode::scalar_opcode(last_ur->Opcode(), bt);
4623 const int vopc = VectorNode::opcode(sopc, bt);
4624 if (!Matcher::match_rule_supported_vector(vopc, vector_length, bt)) {
4625 DEBUG_ONLY( last_ur->dump(); )
4626 assert(false, "do not have normal vector op for this reduction");
4627 continue; // not implemented -> fails
4628 }
4629
4630 // Traverse up the chain of unordered Reductions, checking that it loops back to
4631 // the phi. Check that all unordered Reductions only have a single use, except for
4632 // the last (last_ur), which only has phi as a use in the loop, and all other uses
4633 // are outside the loop.
4634 ReductionNode* current = last_ur;
4635 ReductionNode* first_ur = nullptr;
4636 while (true) {
4637 assert(!current->requires_strict_order(), "sanity");
4638
4639 // Expect no ctrl and a vector_input from within the loop.
4640 Node* ctrl = current->in(0);
4641 Node* vector_input = current->in(2);
4642 if (ctrl != nullptr || get_ctrl(vector_input) != cl) {
4643 DEBUG_ONLY( current->dump(1); )
4644 assert(false, "reduction has ctrl or bad vector_input");
4645 break; // Chain traversal fails.
4646 }
4647
4648 assert(current->vect_type() != nullptr, "must have vector type");
4649 if (current->vect_type() != last_ur->vect_type()) {
4650 // Reductions do not have the same vector type (length and element type).
4651 break; // Chain traversal fails.
4652 }
4653
4654 // Expect single use of an unordered Reduction, except for last_ur.
4655 if (current == last_ur) {
4656 // Expect all uses to be outside the loop, except phi.
4657 for (DUIterator_Fast kmax, k = current->fast_outs(kmax); k < kmax; k++) {
4658 Node* use = current->fast_out(k);
4659 if (use != phi && ctrl_or_self(use) == cl) {
4660 DEBUG_ONLY( current->dump(-1); )
4661 assert(false, "reduction has use inside loop");
4662 // Should not be allowed by SuperWord::mark_reductions
4663 return; // bail out of optimization
4664 }
4665 }
4666 } else {
4667 if (current->outcnt() != 1) {
4668 break; // Chain traversal fails.
4669 }
4670 }
4671
4672 // Expect another unordered Reduction or phi as the scalar input.
4673 Node* scalar_input = current->in(1);
4674 if (is_unordered_reduction(scalar_input) &&
4675 scalar_input->Opcode() == current->Opcode()) {
4676 // Move up the unordered Reduction chain.
4677 current = scalar_input->as_Reduction();
4678 assert(!current->requires_strict_order(), "must be");
4679 } else if (scalar_input == phi) {
4680 // Chain terminates at phi.
4681 first_ur = current;
4682 current = nullptr;
4683 break; // Success.
4684 } else {
4685 // scalar_input is neither phi nor a matching reduction
4686 // Can for example be scalar reduction when we have
4687 // partial vectorization.
4688 break; // Chain traversal fails.
4689 }
4690 }
4691 if (current != nullptr) {
4692 // Chain traversal was not successful.
4693 continue;
4694 }
4695 assert(first_ur != nullptr, "must have successfully terminated chain traversal");
4696
4697 Node* identity_scalar = ReductionNode::make_identity_con_scalar(_igvn, sopc, bt);
4698 set_root_as_ctrl(identity_scalar);
4699 VectorNode* identity_vector = VectorNode::scalar2vector(identity_scalar, vector_length, bt);
4700 register_new_node(identity_vector, C->root());
4701 assert(vec_t == identity_vector->vect_type(), "matching vector type");
4702 VectorNode::trace_new_vector(identity_vector, "Unordered Reduction");
4703
4704 // Turn the scalar phi into a vector phi.
4705 _igvn.rehash_node_delayed(phi);
4706 Node* init = phi->in(1); // Remember init before replacing it.
4707 phi->set_req_X(1, identity_vector, &_igvn);
4708 phi->as_Type()->set_type(vec_t);
4709 _igvn.set_type(phi, vec_t);
4710
4711 // Traverse down the chain of unordered Reductions, and replace them with vector_accumulators.
4712 current = first_ur;
4713 while (true) {
4714 // Create vector_accumulator to replace current.
4715 Node* last_vector_accumulator = current->in(1);
4716 Node* vector_input = current->in(2);
4717 VectorNode* vector_accumulator = VectorNode::make(vopc, last_vector_accumulator, vector_input, vec_t);
4718 register_new_node(vector_accumulator, cl);
4719 _igvn.replace_node(current, vector_accumulator);
4720 VectorNode::trace_new_vector(vector_accumulator, "Unordered Reduction");
4721 if (current == last_ur) {
4722 break;
4723 }
4724 current = vector_accumulator->unique_out()->as_Reduction();
4725 assert(!current->requires_strict_order(), "must be");
4726 }
4727
4728 // Create post-loop reduction.
4729 Node* last_accumulator = phi->in(2);
4730 Node* post_loop_reduction = ReductionNode::make(sopc, nullptr, init, last_accumulator, bt);
4731
4732 // Take over uses of last_accumulator that are not in the loop.
4733 for (DUIterator i = last_accumulator->outs(); last_accumulator->has_out(i); i++) {
4734 Node* use = last_accumulator->out(i);
4735 if (use != phi && use != post_loop_reduction) {
4736 assert(ctrl_or_self(use) != cl, "use must be outside loop");
4737 use->replace_edge(last_accumulator, post_loop_reduction, &_igvn);
4738 --i;
4739 }
4740 }
4741 register_new_node(post_loop_reduction, get_late_ctrl(post_loop_reduction, cl));
4742 VectorNode::trace_new_vector(post_loop_reduction, "Unordered Reduction");
4743
4744 assert(last_accumulator->outcnt() == 2, "last_accumulator has 2 uses: phi and post_loop_reduction");
4745 assert(post_loop_reduction->outcnt() > 0, "should have taken over all non loop uses of last_accumulator");
4746 assert(phi->outcnt() == 1, "accumulator is the only use of phi");
4747 }
4748 }
4749
4750 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4751 for (uint i = 0; i < _data_nodes.size(); i++) {
4752 clone(_data_nodes[i], new_ctrl);
4753 }
4754 }
4755
4756 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4757 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4758 Node* clone = node->clone();
4759 _phase->igvn().register_new_node_with_optimizer(clone);
4760 _orig_to_new.put(node, clone);
4761 _phase->set_ctrl(clone, new_ctrl);
4762 if (node->is_CastII()) {
4763 clone->set_req(0, new_ctrl);
4764 }
4765 }
4766
4767 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4768 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4769 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4770 _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4771 for (uint i = 1; i < node->req(); i++) {
4772 Node** cloned_input = _orig_to_new.get(node->in(i));
4773 if (cloned_input != nullptr) {
4774 // Input was also cloned -> rewire clone to the cloned input.
4775 _phase->igvn().replace_input_of(clone, i, *cloned_input);
4776 }
4777 }
4778 });
4779 }
4780
4781 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4782 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4783 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4784 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4785 Node* new_ctrl) {
4786 for (uint i = 0; i < _data_nodes.size(); i++) {
4787 Node* data_node = _data_nodes[i];
4788 if (data_node->is_Opaque1()) {
4789 transform_opaque_node(transform_strategy, data_node);
4790 } else {
4791 clone(data_node, new_ctrl);
4792 }
4793 }
4794 }
4795
4796 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4797 Node* transformed_node;
4798 if (node->is_OpaqueLoopInit()) {
4799 transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4800 } else {
4801 assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4802 transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4803 }
4804 // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4805 _orig_to_new.put(node, transformed_node);
4806 }