1 /*
2 * Copyright (c) 1999, 2026, 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 *
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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/divnode.hpp"
34 #include "opto/inlinetypenode.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/movenode.hpp"
38 #include "opto/mulnode.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/checkedCast.hpp"
46 #include "utilities/macros.hpp"
47
48 //=============================================================================
49 //------------------------------split_thru_phi---------------------------------
50 // Split Node 'n' through merge point if there is enough win.
51 Node* PhaseIdealLoop::split_thru_phi(Node* n, Node* region, int policy) {
52 if ((n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) ||
53 (n->Opcode() == Op_ConvL2I && n->bottom_type() != TypeInt::INT)) {
54 // ConvI2L/ConvL2I may have type information on it which is unsafe to push up
55 // so disable this for now
56 return nullptr;
57 }
58
59 // Splitting range check CastIIs through a loop induction Phi can
60 // cause new Phis to be created that are left unrelated to the loop
61 // induction Phi and prevent optimizations (vectorization)
62 if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
63 n->in(1) == region->as_CountedLoop()->phi()) {
64 return nullptr;
65 }
66
67 // Inline types should not be split through Phis because they cannot be merged
68 // through Phi nodes but each value input needs to be merged individually.
69 if (n->is_InlineType()) {
70 return nullptr;
71 }
72
73 if (cannot_split_division(n, region)) {
74 return nullptr;
75 }
76
77 SplitThruPhiWins wins(region);
78 assert(!n->is_CFG(), "");
79 assert(region->is_Region(), "");
80
81 const Type* type = n->bottom_type();
82 const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
83 Node* phi;
84 if (t_oop != nullptr && t_oop->is_known_instance_field()) {
85 int iid = t_oop->instance_id();
86 int index = C->get_alias_index(t_oop);
87 int offset = t_oop->offset();
88 phi = new PhiNode(region, type, nullptr, iid, index, offset);
89 } else {
90 phi = PhiNode::make_blank(region, n);
91 }
92 uint old_unique = C->unique();
93 for (uint i = 1; i < region->req(); i++) {
94 Node* x;
95 Node* the_clone = nullptr;
96 if (region->in(i) == C->top()) {
97 x = C->top(); // Dead path? Use a dead data op
98 } else {
99 x = n->clone(); // Else clone up the data op
100 the_clone = x; // Remember for possible deletion.
101 // Alter data node to use pre-phi inputs
102 if (n->in(0) == region)
103 x->set_req( 0, region->in(i) );
104 for (uint j = 1; j < n->req(); j++) {
105 Node* in = n->in(j);
106 if (in->is_Phi() && in->in(0) == region)
107 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
108 }
109 }
110 // Check for a 'win' on some paths
111 const Type* t = x->Value(&_igvn);
112
113 bool singleton = t->singleton();
114
115 // A TOP singleton indicates that there are no possible values incoming
116 // along a particular edge. In most cases, this is OK, and the Phi will
117 // be eliminated later in an Ideal call. However, we can't allow this to
118 // happen if the singleton occurs on loop entry, as the elimination of
119 // the PhiNode may cause the resulting node to migrate back to a previous
120 // loop iteration.
121 if (singleton && t == Type::TOP) {
122 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
123 // irreducible loop may not be indicated by an affirmative is_Loop());
124 // therefore, the only top we can split thru a phi is on a backedge of
125 // a loop.
126 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
127 }
128
129 if (singleton) {
130 wins.add_win(i);
131 x = makecon(t);
132 } else {
133 // We now call Identity to try to simplify the cloned node.
134 // Note that some Identity methods call phase->type(this).
135 // Make sure that the type array is big enough for
136 // our new node, even though we may throw the node away.
137 // (Note: This tweaking with igvn only works because x is a new node.)
138 _igvn.set_type(x, t);
139 // If x is a TypeNode, capture any more-precise type permanently into Node
140 // otherwise it will be not updated during igvn->transform since
141 // igvn->type(x) is set to x->Value() already.
142 x->raise_bottom_type(t);
143 Node* y = x->Identity(&_igvn);
144 if (y != x) {
145 wins.add_win(i);
146 x = y;
147 } else {
148 y = _igvn.hash_find(x);
149 if (y == nullptr) {
150 y = similar_subtype_check(x, region->in(i));
151 }
152 if (y) {
153 wins.add_win(i);
154 x = y;
155 } else {
156 // Else x is a new node we are keeping
157 // We do not need register_new_node_with_optimizer
158 // because set_type has already been called.
159 _igvn._worklist.push(x);
160 }
161 }
162 }
163
164 phi->set_req( i, x );
165
166 if (the_clone == nullptr) {
167 continue;
168 }
169
170 if (the_clone != x) {
171 _igvn.remove_dead_node(the_clone, PhaseIterGVN::NodeOrigin::Speculative);
172 } else if (region->is_Loop() && i == LoopNode::LoopBackControl &&
173 n->is_Load() && can_move_to_inner_loop(n, region->as_Loop(), x)) {
174 // it is not a win if 'x' moved from an outer to an inner loop
175 // this edge case can only happen for Load nodes
176 wins.reset();
177 break;
178 }
179 }
180 // Too few wins?
181 if (!wins.profitable(policy)) {
182 _igvn.remove_dead_node(phi, PhaseIterGVN::NodeOrigin::Speculative);
183 return nullptr;
184 }
185
186 // Record Phi
187 register_new_node( phi, region );
188
189 for (uint i2 = 1; i2 < phi->req(); i2++) {
190 Node *x = phi->in(i2);
191 // If we commoned up the cloned 'x' with another existing Node,
192 // the existing Node picks up a new use. We need to make the
193 // existing Node occur higher up so it dominates its uses.
194 Node *old_ctrl;
195 IdealLoopTree *old_loop;
196
197 if (x->is_Con()) {
198 assert(get_ctrl(x) == C->root(), "constant control is not root");
199 continue;
200 }
201 // The occasional new node
202 if (x->_idx >= old_unique) { // Found a new, unplaced node?
203 old_ctrl = nullptr;
204 old_loop = nullptr; // Not in any prior loop
205 } else {
206 old_ctrl = get_ctrl(x);
207 old_loop = get_loop(old_ctrl); // Get prior loop
208 }
209 // New late point must dominate new use
210 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
211 if (new_ctrl == old_ctrl) // Nothing is changed
212 continue;
213
214 IdealLoopTree *new_loop = get_loop(new_ctrl);
215
216 // Don't move x into a loop if its uses are
217 // outside of loop. Otherwise x will be cloned
218 // for each use outside of this loop.
219 IdealLoopTree *use_loop = get_loop(region);
220 if (!new_loop->is_member(use_loop) &&
221 (old_loop == nullptr || !new_loop->is_member(old_loop))) {
222 // Take early control, later control will be recalculated
223 // during next iteration of loop optimizations.
224 new_ctrl = get_early_ctrl(x);
225 new_loop = get_loop(new_ctrl);
226 }
227 // Set new location
228 set_ctrl(x, new_ctrl);
229 // If changing loop bodies, see if we need to collect into new body
230 if (old_loop != new_loop) {
231 if (old_loop && !old_loop->_child)
232 old_loop->_body.yank(x);
233 if (!new_loop->_child)
234 new_loop->_body.push(x); // Collect body info
235 }
236 }
237
238 split_thru_phi_yank_old_nodes(n, region);
239 _igvn.replace_node(n, phi);
240
241 #ifndef PRODUCT
242 if (TraceLoopOpts) {
243 tty->print_cr("Split %d %s through %d Phi in %d %s",
244 n->_idx, n->Name(), phi->_idx, region->_idx, region->Name());
245 }
246 #endif // !PRODUCT
247
248 return phi;
249 }
250
251 // If the region is a Loop, we are removing the old n,
252 // and need to yank it from the _body. If any phi we
253 // just split through now has no use any more, it also
254 // has to be removed.
255 void PhaseIdealLoop::split_thru_phi_yank_old_nodes(Node* n, Node* region) {
256 IdealLoopTree* region_loop = get_loop(region);
257 if (region->is_Loop() && region_loop->is_innermost()) {
258 region_loop->_body.yank(n);
259 for (uint j = 1; j < n->req(); j++) {
260 PhiNode* phi = n->in(j)->isa_Phi();
261 // Check that phi belongs to the region and only has n as a use.
262 if (phi != nullptr &&
263 phi->in(0) == region &&
264 phi->unique_multiple_edges_out_or_null() == n) {
265 assert(get_ctrl(phi) == region, "sanity");
266 assert(get_ctrl(n) == region, "sanity");
267 region_loop->_body.yank(phi);
268 }
269 }
270 }
271 }
272
273 // Test whether node 'x' can move into an inner loop relative to node 'n'.
274 // Note: The test is not exact. Returns true if 'x' COULD end up in an inner loop,
275 // BUT it can also return true and 'x' is in the outer loop
276 bool PhaseIdealLoop::can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x) {
277 IdealLoopTree* n_loop_tree = get_loop(n_loop);
278 IdealLoopTree* x_loop_tree = get_loop(get_early_ctrl(x));
279 // x_loop_tree should be outer or same loop as n_loop_tree
280 return !x_loop_tree->is_member(n_loop_tree);
281 }
282
283 // Subtype checks that carry profile data don't common so look for a replacement by following edges
284 Node* PhaseIdealLoop::similar_subtype_check(const Node* x, Node* r_in) {
285 if (x->is_SubTypeCheck()) {
286 Node* in1 = x->in(1);
287 for (DUIterator_Fast imax, i = in1->fast_outs(imax); i < imax; i++) {
288 Node* u = in1->fast_out(i);
289 if (u != x && u->is_SubTypeCheck() && u->in(1) == x->in(1) && u->in(2) == x->in(2)) {
290 for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
291 Node* bol = u->fast_out(j);
292 for (DUIterator_Fast kmax, k = bol->fast_outs(kmax); k < kmax; k++) {
293 Node* iff = bol->fast_out(k);
294 // Only dominating subtype checks are interesting: otherwise we risk replacing a subtype check by another with
295 // unrelated profile
296 if (iff->is_If() && is_dominator(iff, r_in)) {
297 return u;
298 }
299 }
300 }
301 }
302 }
303 }
304 return nullptr;
305 }
306
307 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
308 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
309 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
310 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
311 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
312 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
313 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
314 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
315 const Type* zero;
316 switch (n->Opcode()) {
317 case Op_DivI:
318 case Op_ModI:
319 case Op_UDivI:
320 case Op_UModI:
321 zero = TypeInt::ZERO;
322 break;
323 case Op_DivL:
324 case Op_ModL:
325 case Op_UDivL:
326 case Op_UModL:
327 zero = TypeLong::ZERO;
328 break;
329 default:
330 return false;
331 }
332
333 if (n->in(0) != nullptr) {
334 // Cannot split through phi if Div or Mod node has a control dependency to a zero check.
335 return true;
336 }
337
338 Node* divisor = n->in(2);
339 return is_divisor_loop_phi(divisor, region) &&
340 loop_phi_backedge_type_contains_zero(divisor, zero);
341 }
342
343 bool PhaseIdealLoop::is_divisor_loop_phi(const Node* divisor, const Node* loop) {
344 return loop->is_Loop() && divisor->is_Phi() && divisor->in(0) == loop;
345 }
346
347 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
348 return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
349 }
350
351 //------------------------------dominated_by------------------------------------
352 // Replace the dominated test with an obvious true or false. Place it on the
353 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
354 // live path up to the dominating control.
355 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool prevdom_not_imply_this) {
356 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
357
358 // prevdom is the dominating projection of the dominating test.
359 assert(iff->Opcode() == Op_If ||
360 iff->Opcode() == Op_CountedLoopEnd ||
361 iff->Opcode() == Op_LongCountedLoopEnd ||
362 iff->Opcode() == Op_RangeCheck ||
363 iff->Opcode() == Op_ParsePredicate,
364 "Check this code when new subtype is added");
365
366 int pop = prevdom->Opcode();
367 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
368 if (flip) {
369 if (pop == Op_IfTrue)
370 pop = Op_IfFalse;
371 else
372 pop = Op_IfTrue;
373 }
374 // 'con' is set to true or false to kill the dominated test.
375 Node* con = makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
376 // Hack the dominated test
377 _igvn.replace_input_of(iff, 1, con);
378
379 // If I don't have a reachable TRUE and FALSE path following the IfNode then
380 // I can assume this path reaches an infinite loop. In this case it's not
381 // important to optimize the data Nodes - either the whole compilation will
382 // be tossed or this path (and all data Nodes) will go dead.
383 if (iff->outcnt() != 2) {
384 return;
385 }
386
387 // Make control-dependent data Nodes on the live path (path that will remain
388 // once the dominated IF is removed) become control-dependent on the
389 // dominating projection.
390 Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
391
392 if (dp == nullptr) {
393 return;
394 }
395
396 rewire_safe_outputs_to_dominator(dp, prevdom, prevdom_not_imply_this);
397 }
398
399 void PhaseIdealLoop::rewire_safe_outputs_to_dominator(Node* source, Node* dominator, const bool dominator_not_imply_source) {
400 IdealLoopTree* old_loop = get_loop(source);
401
402 for (DUIterator_Fast imax, i = source->fast_outs(imax); i < imax; i++) {
403 Node* out = source->fast_out(i); // Control-dependent node
404 if (out->depends_only_on_test()) {
405 assert(out->in(0) == source, "must be control dependent on source");
406 _igvn.replace_input_of(out, 0, dominator);
407 if (dominator_not_imply_source) {
408 // Because of Loop Predication, Loads and range check Cast nodes that are control dependent on this range
409 // check (that is about to be removed) now depend on multiple dominating Hoisted Check Predicates. After the
410 // removal of this range check, these control dependent nodes end up at the lowest/nearest dominating predicate
411 // in the graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
412 // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the lowest
413 // dominating check.
414 Node* clone = out->pin_node_under_control();
415 if (clone != nullptr) {
416 clone = _igvn.register_new_node_with_optimizer(clone, out);
417 _igvn.replace_node(out, clone);
418 out = clone;
419 }
420 }
421 set_early_ctrl(out, false);
422 IdealLoopTree* new_loop = get_loop(get_ctrl(out));
423 if (old_loop != new_loop) {
424 if (!old_loop->_child) {
425 old_loop->_body.yank(out);
426 }
427 if (!new_loop->_child) {
428 new_loop->_body.push(out);
429 }
430 }
431 --i;
432 --imax;
433 }
434 }
435 }
436
437 //------------------------------has_local_phi_input----------------------------
438 // Return TRUE if 'n' has Phi inputs from its local block and no other
439 // block-local inputs (all non-local-phi inputs come from earlier blocks)
440 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
441 Node *n_ctrl = get_ctrl(n);
442 // See if some inputs come from a Phi in this block, or from before
443 // this block.
444 uint i;
445 for( i = 1; i < n->req(); i++ ) {
446 Node *phi = n->in(i);
447 if( phi->is_Phi() && phi->in(0) == n_ctrl )
448 break;
449 }
450 if( i >= n->req() )
451 return nullptr; // No Phi inputs; nowhere to clone thru
452
453 // Check for inputs created between 'n' and the Phi input. These
454 // must split as well; they have already been given the chance
455 // (courtesy of a post-order visit) and since they did not we must
456 // recover the 'cost' of splitting them by being very profitable
457 // when splitting 'n'. Since this is unlikely we simply give up.
458 for( i = 1; i < n->req(); i++ ) {
459 Node *m = n->in(i);
460 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
461 // We allow the special case of AddP's with no local inputs.
462 // This allows us to split-up address expressions.
463 if (m->is_AddP() &&
464 get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
465 get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
466 get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
467 // Move the AddP up to the dominating point. That's fine because control of m's inputs
468 // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
469 Node* c = find_non_split_ctrl(idom(n_ctrl));
470 if (c->is_OuterStripMinedLoop()) {
471 c->as_Loop()->verify_strip_mined(1);
472 c = c->in(LoopNode::EntryControl);
473 }
474 set_ctrl_and_loop(m, c);
475 continue;
476 }
477 return nullptr;
478 }
479 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
480 }
481
482 return n_ctrl;
483 }
484
485 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
486 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
487 assert(bt == T_INT || bt == T_LONG, "only for integers");
488 int n_op = n->Opcode();
489
490 if (n_op == Op_LShift(bt)) {
491 // Scale is loop invariant
492 Node* scale = n->in(2);
493 Node* scale_ctrl = get_ctrl(scale);
494 IdealLoopTree* scale_loop = get_loop(scale_ctrl);
495 if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
496 return nullptr;
497 }
498 const TypeInt* scale_t = scale->bottom_type()->isa_int();
499 if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
500 return nullptr; // Dont bother with byte/short masking
501 }
502 // Add must vary with loop (else shift would be loop-invariant)
503 Node* add = n->in(1);
504 Node* add_ctrl = get_ctrl(add);
505 IdealLoopTree* add_loop = get_loop(add_ctrl);
506 if (n_loop != add_loop) {
507 return nullptr; // happens w/ evil ZKM loops
508 }
509
510 // Convert I-V into I+ (0-V); same for V-I
511 if (add->Opcode() == Op_Sub(bt) &&
512 _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
513 assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
514 Node* zero = integercon(0, bt);
515 Node* neg = SubNode::make(zero, add->in(2), bt);
516 register_new_node_with_ctrl_of(neg, add->in(2));
517 add = AddNode::make(add->in(1), neg, bt);
518 register_new_node(add, add_ctrl);
519 }
520 if (add->Opcode() != Op_Add(bt)) return nullptr;
521 assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
522 // See if one add input is loop invariant
523 Node* add_var = add->in(1);
524 Node* add_var_ctrl = get_ctrl(add_var);
525 IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
526 Node* add_invar = add->in(2);
527 Node* add_invar_ctrl = get_ctrl(add_invar);
528 IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
529 if (add_invar_loop == n_loop) {
530 // Swap to find the invariant part
531 add_invar = add_var;
532 add_invar_ctrl = add_var_ctrl;
533 add_invar_loop = add_var_loop;
534 add_var = add->in(2);
535 } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
536 return nullptr;
537 }
538 if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
539 return nullptr; // No invariant part of the add?
540 }
541
542 // Yes! Reshape address expression!
543 Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
544 Node* inv_scale_ctrl =
545 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
546 add_invar_ctrl : scale_ctrl;
547 register_new_node(inv_scale, inv_scale_ctrl);
548 Node* var_scale = LShiftNode::make(add_var, scale, bt);
549 register_new_node(var_scale, n_ctrl);
550 Node* var_add = AddNode::make(var_scale, inv_scale, bt);
551 register_new_node(var_add, n_ctrl);
552 _igvn.replace_node(n, var_add);
553 return var_add;
554 }
555 return nullptr;
556 }
557
558 //------------------------------remix_address_expressions----------------------
559 // Rework addressing expressions to get the most loop-invariant stuff
560 // moved out. We'd like to do all associative operators, but it's especially
561 // important (common) to do address expressions.
562 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
563 if (!has_ctrl(n)) return nullptr;
564 Node* n_ctrl = get_ctrl(n);
565 IdealLoopTree* n_loop = get_loop(n_ctrl);
566
567 // See if 'n' mixes loop-varying and loop-invariant inputs and
568 // itself is loop-varying.
569
570 // Only interested in binary ops (and AddP)
571 if (n->req() < 3 || n->req() > 4) return nullptr;
572
573 Node* n1_ctrl = get_ctrl(n->in( 1));
574 Node* n2_ctrl = get_ctrl(n->in( 2));
575 Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
576 IdealLoopTree* n1_loop = get_loop(n1_ctrl);
577 IdealLoopTree* n2_loop = get_loop(n2_ctrl);
578 IdealLoopTree* n3_loop = get_loop(n3_ctrl);
579
580 // Does one of my inputs spin in a tighter loop than self?
581 if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
582 (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
583 (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
584 return nullptr; // Leave well enough alone
585 }
586
587 // Is at least one of my inputs loop-invariant?
588 if (n1_loop == n_loop &&
589 n2_loop == n_loop &&
590 n3_loop == n_loop) {
591 return nullptr; // No loop-invariant inputs
592 }
593
594 Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
595 if (res != nullptr) {
596 return res;
597 }
598 res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
599 if (res != nullptr) {
600 return res;
601 }
602
603 int n_op = n->Opcode();
604 // Replace (I+V) with (V+I)
605 if (n_op == Op_AddI ||
606 n_op == Op_AddL ||
607 n_op == Op_AddF ||
608 n_op == Op_AddD ||
609 n_op == Op_MulI ||
610 n_op == Op_MulL ||
611 n_op == Op_MulF ||
612 n_op == Op_MulD) {
613 if (n2_loop == n_loop) {
614 assert(n1_loop != n_loop, "");
615 n->swap_edges(1, 2);
616 }
617 }
618
619 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
620 // but not if I2 is a constant. Skip for irreducible loops.
621 if (n_op == Op_AddP && n_loop->_head->is_Loop()) {
622 if (n2_loop == n_loop && n3_loop != n_loop) {
623 if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
624 Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
625 Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
626 IdealLoopTree* n22loop = get_loop(n22_ctrl);
627 IdealLoopTree* n23_loop = get_loop(n23_ctrl);
628 if (n22loop != n_loop && n22loop->is_member(n_loop) &&
629 n23_loop == n_loop) {
630 Node* add1 = AddPNode::make_with_base(n->in(1), n->in(2)->in(2), n->in(3));
631 // Stuff new AddP in the loop preheader
632 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
633 Node* add2 = AddPNode::make_with_base(n->in(1), add1, n->in(2)->in(3));
634 register_new_node(add2, n_ctrl);
635 _igvn.replace_node(n, add2);
636 return add2;
637 }
638 }
639 }
640
641 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
642 if (n2_loop != n_loop && n3_loop == n_loop) {
643 if (n->in(3)->Opcode() == Op_AddX) {
644 Node* V = n->in(3)->in(1);
645 Node* I = n->in(3)->in(2);
646 if (ctrl_is_member(n_loop, V)) {
647 } else {
648 Node *tmp = V; V = I; I = tmp;
649 }
650 if (!ctrl_is_member(n_loop, I)) {
651 Node* add1 = AddPNode::make_with_base(n->in(1), n->in(2), I);
652 // Stuff new AddP in the loop preheader
653 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
654 Node* add2 = AddPNode::make_with_base(n->in(1), add1, V);
655 register_new_node(add2, n_ctrl);
656 _igvn.replace_node(n, add2);
657 return add2;
658 }
659 }
660 }
661 }
662
663 return nullptr;
664 }
665
666 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
667 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
668 assert(n->Opcode() == Op_AddI, "sanity");
669 Node * nn = nullptr;
670 Node * in1 = n->in(1);
671 Node * in2 = n->in(2);
672 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
673 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
674 if (loop_n->is_counted() &&
675 loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
676 Matcher::match_rule_supported(Op_MulAddVS2VI) &&
677 Matcher::match_rule_supported(Op_MulAddS2I)) {
678 Node* mul_in1 = in1->in(1);
679 Node* mul_in2 = in1->in(2);
680 Node* mul_in3 = in2->in(1);
681 Node* mul_in4 = in2->in(2);
682 if (mul_in1->Opcode() == Op_LoadS &&
683 mul_in2->Opcode() == Op_LoadS &&
684 mul_in3->Opcode() == Op_LoadS &&
685 mul_in4->Opcode() == Op_LoadS) {
686 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
687 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
688 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
689 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
690 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
691 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
692 // All nodes should be in the same counted loop.
693 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
694 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
695 Node* adr1 = mul_in1->in(MemNode::Address);
696 Node* adr2 = mul_in2->in(MemNode::Address);
697 Node* adr3 = mul_in3->in(MemNode::Address);
698 Node* adr4 = mul_in4->in(MemNode::Address);
699 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
700 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
701 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
702 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
703 register_new_node_with_ctrl_of(nn, n);
704 _igvn.replace_node(n, nn);
705 return nn;
706 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
707 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
708 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
709 register_new_node_with_ctrl_of(nn, n);
710 _igvn.replace_node(n, nn);
711 return nn;
712 }
713 }
714 }
715 }
716 }
717 }
718 return nn;
719 }
720
721 //------------------------------conditional_move-------------------------------
722 // Attempt to replace a Phi with a conditional move. We have some pretty
723 // strict profitability requirements. All Phis at the merge point must
724 // be converted, so we can remove the control flow. We need to limit the
725 // number of c-moves to a small handful. All code that was in the side-arms
726 // of the CFG diamond is now speculatively executed. This code has to be
727 // "cheap enough". We are pretty much limited to CFG diamonds that merge
728 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
729 Node *PhaseIdealLoop::conditional_move( Node *region ) {
730
731 assert(region->is_Region(), "sanity check");
732 if (region->req() != 3) return nullptr;
733
734 // Check for CFG diamond
735 Node *lp = region->in(1);
736 Node *rp = region->in(2);
737 if (!lp || !rp) return nullptr;
738 Node *lp_c = lp->in(0);
739 if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
740 IfNode *iff = lp_c->as_If();
741
742 // Check for ops pinned in an arm of the diamond.
743 // Can't remove the control flow in this case
744 if (lp->outcnt() > 1) return nullptr;
745 if (rp->outcnt() > 1) return nullptr;
746
747 IdealLoopTree* r_loop = get_loop(region);
748 assert(r_loop == get_loop(iff), "sanity");
749 // Always convert to CMOVE if all results are used only outside this loop.
750 bool used_inside_loop = (r_loop == _ltree_root);
751
752 // Check profitability
753 int cost = 0;
754 int phis = 0;
755 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
756 Node *out = region->fast_out(i);
757 if (!out->is_Phi()) continue; // Ignore other control edges, etc
758 phis++;
759 PhiNode* phi = out->as_Phi();
760 BasicType bt = phi->type()->basic_type();
761 switch (bt) {
762 case T_DOUBLE:
763 case T_FLOAT:
764 if (C->use_cmove()) {
765 continue; //TODO: maybe we want to add some cost
766 }
767 cost += Matcher::float_cmove_cost(); // Could be very expensive
768 break;
769 case T_LONG: {
770 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
771 }
772 case T_INT: // These all CMOV fine
773 case T_ADDRESS: { // (RawPtr)
774 cost++;
775 break;
776 }
777 case T_NARROWOOP: // Fall through
778 case T_OBJECT: { // Base oops are OK, but not derived oops
779 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
780 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
781 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
782 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
783 // have a Phi for the base here that we convert to a CMOVE all is well
784 // and good. But if the base is dead, we'll not make a CMOVE. Later
785 // the allocator will have to produce a base by creating a CMOVE of the
786 // relevant bases. This puts the allocator in the business of
787 // manufacturing expensive instructions, generally a bad plan.
788 // Just Say No to Conditionally-Moved Derived Pointers.
789 if (tp && tp->offset() != 0)
790 return nullptr;
791 cost++;
792 break;
793 }
794 default:
795 return nullptr; // In particular, can't do memory or I/O
796 }
797 // Add in cost any speculative ops
798 for (uint j = 1; j < region->req(); j++) {
799 Node *proj = region->in(j);
800 Node *inp = phi->in(j);
801 if (inp->isa_InlineType()) {
802 // TODO 8302217 This prevents PhiNode::push_inline_types_through
803 return nullptr;
804 }
805 if (get_ctrl(inp) == proj) { // Found local op
806 cost++;
807 // Check for a chain of dependent ops; these will all become
808 // speculative in a CMOV.
809 for (uint k = 1; k < inp->req(); k++)
810 if (get_ctrl(inp->in(k)) == proj)
811 cost += ConditionalMoveLimit; // Too much speculative goo
812 }
813 }
814 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
815 // This will likely Split-If, a higher-payoff operation.
816 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
817 Node* use = phi->fast_out(k);
818 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
819 cost += ConditionalMoveLimit;
820 // Is there a use inside the loop?
821 // Note: check only basic types since CMoveP is pinned.
822 if (!used_inside_loop && is_java_primitive(bt)) {
823 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
824 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
825 used_inside_loop = true;
826 }
827 }
828 }
829 }//for
830 Node* bol = iff->in(1);
831 assert(!bol->is_OpaqueInitializedAssertionPredicate(), "Initialized Assertion Predicates cannot form a diamond with Halt");
832 if (bol->is_OpaqueTemplateAssertionPredicate()) {
833 // Ignore Template Assertion Predicates with OpaqueTemplateAssertionPredicate nodes.
834 return nullptr;
835 }
836 if (bol->is_OpaqueMultiversioning()) {
837 assert(bol->as_OpaqueMultiversioning()->is_useless(), "Must be useless, i.e. fast main loop has already disappeared.");
838 // Ignore multiversion_if that just lost its loops. The OpaqueMultiversioning is marked useless,
839 // and will make the multiversion_if constant fold in the next IGVN round.
840 return nullptr;
841 }
842 if (!bol->is_Bool()) {
843 assert(false, "Expected Bool, but got %s", NodeClassNames[bol->Opcode()]);
844 return nullptr;
845 }
846 int cmp_op = bol->in(1)->Opcode();
847 if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
848 return nullptr;
849 }
850 // It is expensive to generate flags from a float compare.
851 // Avoid duplicated float compare.
852 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
853
854 float infrequent_prob = PROB_UNLIKELY_MAG(3);
855 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
856 if (used_inside_loop) {
857 if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
858
859 // BlockLayoutByFrequency optimization moves infrequent branch
860 // from hot path. No point in CMOV'ing in such case (110 is used
861 // instead of 100 to take into account not exactness of float value).
862 if (BlockLayoutByFrequency) {
863 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
864 }
865 }
866 // Check for highly predictable branch. No point in CMOV'ing if
867 // we are going to predict accurately all the time.
868 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
869 //keep going
870 } else if (iff->_prob < infrequent_prob ||
871 iff->_prob > (1.0f - infrequent_prob))
872 return nullptr;
873
874 // --------------
875 // Now replace all Phis with CMOV's
876 Node *cmov_ctrl = iff->in(0);
877 uint flip = (lp->Opcode() == Op_IfTrue);
878 Node_List wq;
879 while (1) {
880 PhiNode* phi = nullptr;
881 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
882 Node *out = region->fast_out(i);
883 if (out->is_Phi()) {
884 phi = out->as_Phi();
885 break;
886 }
887 }
888 if (phi == nullptr || _igvn.type(phi) == Type::TOP || !CMoveNode::supported(_igvn.type(phi))) {
889 break;
890 }
891 // Move speculative ops
892 wq.push(phi);
893 while (wq.size() > 0) {
894 Node *n = wq.pop();
895 for (uint j = 1; j < n->req(); j++) {
896 Node* m = n->in(j);
897 if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
898 set_ctrl(m, cmov_ctrl);
899 wq.push(m);
900 }
901 }
902 }
903 Node* cmov = CMoveNode::make(iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
904 register_new_node(cmov, cmov_ctrl);
905 _igvn.replace_node(phi, cmov);
906 #ifndef PRODUCT
907 if (TraceLoopOpts) {
908 tty->print("CMOV ");
909 r_loop->dump_head();
910 if (Verbose) {
911 bol->in(1)->dump(1);
912 cmov->dump(1);
913 }
914 }
915 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
916 #endif
917 }
918
919 // The useless CFG diamond will fold up later; see the optimization in
920 // RegionNode::Ideal.
921 _igvn._worklist.push(region);
922
923 return iff->in(1);
924 }
925
926 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
927 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
928 Node* u = m->fast_out(i);
929 if (u->is_CFG()) {
930 if (u->is_NeverBranch()) {
931 u = u->as_NeverBranch()->proj_out(0);
932 enqueue_cfg_uses(u, wq);
933 } else {
934 wq.push(u);
935 }
936 }
937 }
938 }
939
940 // Try moving a store out of a loop, right before the loop
941 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
942 // Store has to be first in the loop body
943 IdealLoopTree *n_loop = get_loop(n_ctrl);
944 if (n->is_Store() && n_loop != _ltree_root &&
945 n_loop->is_loop() && n_loop->_head->is_Loop() &&
946 n->in(0) != nullptr) {
947 Node* address = n->in(MemNode::Address);
948 Node* value = n->in(MemNode::ValueIn);
949 Node* mem = n->in(MemNode::Memory);
950
951 // - address and value must be loop invariant
952 // - memory must be a memory Phi for the loop
953 // - Store must be the only store on this memory slice in the
954 // loop: if there's another store following this one then value
955 // written at iteration i by the second store could be overwritten
956 // at iteration i+n by the first store: it's not safe to move the
957 // first store out of the loop
958 // - nothing must observe the memory Phi: it guarantees no read
959 // before the store, we are also guaranteed the store post
960 // dominates the loop head (ignoring a possible early
961 // exit). Otherwise there would be extra Phi involved between the
962 // loop's Phi and the store.
963 // - there must be no early exit from the loop before the Store
964 // (such an exit most of the time would be an extra use of the
965 // memory Phi but sometimes is a bottom memory Phi that takes the
966 // store as input).
967
968 if (!ctrl_is_member(n_loop, address) &&
969 !ctrl_is_member(n_loop, value) &&
970 mem->is_Phi() && mem->in(0) == n_loop->_head &&
971 mem->outcnt() == 1 &&
972 mem->in(LoopNode::LoopBackControl) == n) {
973
974 assert(n_loop->_tail != nullptr, "need a tail");
975 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
976
977 // Verify that there's no early exit of the loop before the store.
978 bool ctrl_ok = false;
979 {
980 // Follow control from loop head until n, we exit the loop or
981 // we reach the tail
982 ResourceMark rm;
983 Unique_Node_List wq;
984 wq.push(n_loop->_head);
985
986 for (uint next = 0; next < wq.size(); ++next) {
987 Node *m = wq.at(next);
988 if (m == n->in(0)) {
989 ctrl_ok = true;
990 continue;
991 }
992 assert(!has_ctrl(m), "should be CFG");
993 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
994 ctrl_ok = false;
995 break;
996 }
997 enqueue_cfg_uses(m, wq);
998 if (wq.size() > 10) {
999 ctrl_ok = false;
1000 break;
1001 }
1002 }
1003 }
1004 if (ctrl_ok) {
1005 // move the Store
1006 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
1007 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
1008 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
1009 // Disconnect the phi now. An empty phi can confuse other
1010 // optimizations in this pass of loop opts.
1011 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
1012 n_loop->_body.yank(mem);
1013
1014 set_ctrl_and_loop(n, n->in(0));
1015
1016 return n;
1017 }
1018 }
1019 }
1020 return nullptr;
1021 }
1022
1023 // Try moving a store out of a loop, right after the loop
1024 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
1025 if (n->is_Store() && n->in(0) != nullptr) {
1026 Node *n_ctrl = get_ctrl(n);
1027 IdealLoopTree *n_loop = get_loop(n_ctrl);
1028 // Store must be in a loop
1029 if (n_loop != _ltree_root && !n_loop->_irreducible) {
1030 Node* address = n->in(MemNode::Address);
1031 Node* value = n->in(MemNode::ValueIn);
1032 // address must be loop invariant
1033 if (!ctrl_is_member(n_loop, address)) {
1034 // Store must be last on this memory slice in the loop and
1035 // nothing in the loop must observe it
1036 Node* phi = nullptr;
1037 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1038 Node* u = n->fast_out(i);
1039 if (has_ctrl(u)) { // control use?
1040 if (!ctrl_is_member(n_loop, u)) {
1041 continue;
1042 }
1043 if (u->is_Phi() && u->in(0) == n_loop->_head) {
1044 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1045 // multiple phis on the same slice are possible
1046 if (phi != nullptr) {
1047 return;
1048 }
1049 phi = u;
1050 continue;
1051 }
1052 }
1053 return;
1054 }
1055 if (phi != nullptr) {
1056 // Nothing in the loop before the store (next iteration)
1057 // must observe the stored value
1058 bool mem_ok = true;
1059 {
1060 ResourceMark rm;
1061 Unique_Node_List wq;
1062 wq.push(phi);
1063 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1064 Node *m = wq.at(next);
1065 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1066 Node* u = m->fast_out(i);
1067 if (u->is_Store() || u->is_Phi()) {
1068 if (u != n) {
1069 wq.push(u);
1070 mem_ok = (wq.size() <= 10);
1071 }
1072 } else {
1073 mem_ok = false;
1074 break;
1075 }
1076 }
1077 }
1078 }
1079 if (mem_ok) {
1080 // Move the store out of the loop if the LCA of all
1081 // users (except for the phi) is outside the loop.
1082 Node* hook = new Node(1);
1083 hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1084 _igvn.rehash_node_delayed(phi);
1085 int count = phi->replace_edge(n, hook, &_igvn);
1086 assert(count > 0, "inconsistent phi");
1087
1088 // Compute latest point this store can go
1089 Node* lca = get_late_ctrl(n, get_ctrl(n));
1090 if (lca->is_OuterStripMinedLoop()) {
1091 lca = lca->in(LoopNode::EntryControl);
1092 }
1093 if (n_loop->is_member(get_loop(lca))) {
1094 // LCA is in the loop - bail out
1095 _igvn.replace_node(hook, n);
1096 return;
1097 }
1098 #ifdef ASSERT
1099 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1100 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1101 n_loop->_head->as_Loop()->verify_strip_mined(1);
1102 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1103 IdealLoopTree* outer_loop = get_loop(outer);
1104 assert(n_loop->_parent == outer_loop, "broken loop tree");
1105 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1106 }
1107 #endif
1108 lca = place_outside_loop(lca, n_loop);
1109 assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1110 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");
1111
1112 // Move store out of the loop
1113 _igvn.replace_node(hook, n->in(MemNode::Memory));
1114 _igvn.replace_input_of(n, 0, lca);
1115 set_ctrl_and_loop(n, lca);
1116
1117 // Disconnect the phi now. An empty phi can confuse other
1118 // optimizations in this pass of loop opts..
1119 if (phi->in(LoopNode::LoopBackControl) == phi) {
1120 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1121 n_loop->_body.yank(phi);
1122 }
1123 }
1124 }
1125 }
1126 }
1127 }
1128 }
1129
1130 // We can't use immutable memory for the flat array check because we are loading the mark word which is
1131 // mutable. Although the bits we are interested in are immutable (we check for markWord::unlocked_value),
1132 // we need to use raw memory to not break anti dependency analysis. Below code will attempt to still move
1133 // flat array checks out of loops, mainly to enable loop unswitching.
1134 void PhaseIdealLoop::move_flat_array_check_out_of_loop(Node* n) {
1135 // Skip checks for more than one array
1136 if (n->req() > 3) {
1137 return;
1138 }
1139 Node* mem = n->in(FlatArrayCheckNode::Memory);
1140 Node* array = n->in(FlatArrayCheckNode::ArrayOrKlass)->uncast();
1141 IdealLoopTree* check_loop = get_loop(get_ctrl(n));
1142 IdealLoopTree* ary_loop = get_loop(get_ctrl(array));
1143
1144 // Check if array is loop invariant
1145 if (!check_loop->is_member(ary_loop)) {
1146 // Walk up memory graph from the check until we leave the loop
1147 VectorSet wq;
1148 wq.set(mem->_idx);
1149 while (check_loop->is_member(get_loop(ctrl_or_self(mem)))) {
1150 if (mem->is_Phi()) {
1151 mem = mem->in(1);
1152 } else if (mem->is_MergeMem()) {
1153 mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
1154 } else if (mem->is_Proj()) {
1155 mem = mem->in(0);
1156 } else if (mem->is_MemBar() || mem->is_SafePoint()) {
1157 mem = mem->in(TypeFunc::Memory);
1158 } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
1159 mem = mem->in(MemNode::Memory);
1160 } else {
1161 #ifdef ASSERT
1162 mem->dump();
1163 #endif
1164 ShouldNotReachHere();
1165 }
1166 if (wq.test_set(mem->_idx)) {
1167 return;
1168 }
1169 }
1170 // Replace memory input and re-compute ctrl to move the check out of the loop
1171 _igvn.replace_input_of(n, 1, mem);
1172 set_ctrl_and_loop(n, get_early_ctrl(n));
1173 Node* bol = n->unique_out();
1174 set_ctrl_and_loop(bol, get_early_ctrl(bol));
1175 }
1176 }
1177
1178 //------------------------------split_if_with_blocks_pre-----------------------
1179 // Do the real work in a non-recursive function. Data nodes want to be
1180 // cloned in the pre-order so they can feed each other nicely.
1181 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1182 // Cloning these guys is unlikely to win
1183 int n_op = n->Opcode();
1184 if (n_op == Op_MergeMem) {
1185 return n;
1186 }
1187 if (n->is_Proj()) {
1188 return n;
1189 }
1190
1191 if (n->isa_FlatArrayCheck()) {
1192 move_flat_array_check_out_of_loop(n);
1193 return n;
1194 }
1195
1196 // Do not clone-up CmpFXXX variations, as these are always
1197 // followed by a CmpI
1198 if (n->is_Cmp()) {
1199 return n;
1200 }
1201 // Attempt to use a conditional move instead of a phi/branch
1202 if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1203 Node *cmov = conditional_move( n );
1204 if (cmov) {
1205 return cmov;
1206 }
1207 }
1208 if (n->is_CFG() || n->is_LoadStore()) {
1209 return n;
1210 }
1211 if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1212 if (!C->major_progress()) { // If chance of no more loop opts...
1213 _igvn._worklist.push(n); // maybe we'll remove them
1214 }
1215 return n;
1216 }
1217
1218 if (n->is_Con()) {
1219 return n; // No cloning for Con nodes
1220 }
1221
1222 Node *n_ctrl = get_ctrl(n);
1223 if (!n_ctrl) {
1224 return n; // Dead node
1225 }
1226
1227 Node* res = try_move_store_before_loop(n, n_ctrl);
1228 if (res != nullptr) {
1229 return n;
1230 }
1231
1232 // Attempt to remix address expressions for loop invariants
1233 Node *m = remix_address_expressions( n );
1234 if( m ) return m;
1235
1236 if (n_op == Op_AddI) {
1237 Node *nn = convert_add_to_muladd( n );
1238 if ( nn ) return nn;
1239 }
1240
1241 if (n->is_ConstraintCast() && n->as_ConstraintCast()->dependency().narrows_type()) {
1242 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1243 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1244 // Node control inputs don't necessarily agree with loop control info (due to
1245 // transformations happened in between), thus additional dominance check is needed
1246 // to keep loop info valid.
1247 if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1248 _igvn.replace_node(n, dom_cast);
1249 return dom_cast;
1250 }
1251 }
1252
1253 // Determine if the Node has inputs from some local Phi.
1254 // Returns the block to clone thru.
1255 Node *n_blk = has_local_phi_input( n );
1256 if( !n_blk ) return n;
1257
1258 // Do not clone the trip counter through on a CountedLoop
1259 // (messes up the canonical shape).
1260 if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1261 (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1262 return n;
1263 }
1264 // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1265 if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1266 n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1267 return n;
1268 }
1269
1270 // Check for having no control input; not pinned. Allow
1271 // dominating control.
1272 if (n->in(0)) {
1273 Node *dom = idom(n_blk);
1274 if (dom_lca(n->in(0), dom) != n->in(0)) {
1275 return n;
1276 }
1277 }
1278 // Policy: when is it profitable. You must get more wins than
1279 // policy before it is considered profitable. Policy is usually 0,
1280 // so 1 win is considered profitable. Big merges will require big
1281 // cloning, so get a larger policy.
1282 int policy = n_blk->req() >> 2;
1283
1284 // If the loop is a candidate for range check elimination,
1285 // delay splitting through it's phi until a later loop optimization
1286 if (n_blk->is_BaseCountedLoop()) {
1287 IdealLoopTree *lp = get_loop(n_blk);
1288 if (lp && lp->_rce_candidate) {
1289 return n;
1290 }
1291 }
1292
1293 if (must_throttle_split_if()) return n;
1294
1295 // Split 'n' through the merge point if it is profitable, replacing it with a new phi.
1296 Node* phi = split_thru_phi(n, n_blk, policy);
1297 if (phi == nullptr) { return n; }
1298
1299 // Moved a load around the loop, 'en-registering' something.
1300 if (n_blk->is_Loop() && n->is_Load() &&
1301 !phi->in(LoopNode::LoopBackControl)->is_Load())
1302 C->set_major_progress();
1303
1304 return phi;
1305 }
1306
1307 static bool merge_point_too_heavy(Compile* C, Node* region) {
1308 // Bail out if the region and its phis have too many users.
1309 int weight = 0;
1310 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1311 weight += region->fast_out(i)->outcnt();
1312 }
1313 int nodes_left = C->max_node_limit() - C->live_nodes();
1314 if (weight * 8 > nodes_left) {
1315 if (PrintOpto) {
1316 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1317 }
1318 return true;
1319 } else {
1320 return false;
1321 }
1322 }
1323
1324 static bool merge_point_safe(Node* region) {
1325 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1326 // having a PhiNode input. This sidesteps the dangerous case where the split
1327 // ConvI2LNode may become TOP if the input Value() does not
1328 // overlap the ConvI2L range, leaving a node which may not dominate its
1329 // uses.
1330 // A better fix for this problem can be found in the BugTraq entry, but
1331 // expediency for Mantis demands this hack.
1332 #ifdef _LP64
1333 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1334 Node* n = region->fast_out(i);
1335 if (n->is_Phi()) {
1336 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1337 Node* m = n->fast_out(j);
1338 if (m->Opcode() == Op_ConvI2L)
1339 return false;
1340 if (m->is_CastII()) {
1341 return false;
1342 }
1343 }
1344 }
1345 }
1346 #endif
1347 return true;
1348 }
1349
1350
1351 //------------------------------place_outside_loop---------------------------------
1352 // Place some computation outside of this loop on the path to the use passed as argument
1353 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1354 Node* head = loop->_head;
1355 assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1356 if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1357 loop = loop->_parent;
1358 assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1359 }
1360
1361 // Pick control right outside the loop
1362 for (;;) {
1363 Node* dom = idom(useblock);
1364 if (loop->is_member(get_loop(dom))) {
1365 break;
1366 }
1367 useblock = dom;
1368 }
1369 assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1370 return useblock;
1371 }
1372
1373
1374 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1375 if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1376 return false;
1377 }
1378 if (!n->in(0)->is_Region()) {
1379 return false;
1380 }
1381
1382 Node* region = n->in(0);
1383 Node* dom = idom(region);
1384 if (!dom->is_If() || !n->as_If()->same_condition(dom, &_igvn)) {
1385 return false;
1386 }
1387 IfNode* dom_if = dom->as_If();
1388 IfTrueNode* proj_true = dom_if->true_proj();
1389 IfFalseNode* proj_false = dom_if->false_proj();
1390
1391 for (uint i = 1; i < region->req(); i++) {
1392 if (is_dominator(proj_true, region->in(i))) {
1393 continue;
1394 }
1395 if (is_dominator(proj_false, region->in(i))) {
1396 continue;
1397 }
1398 return false;
1399 }
1400
1401 return true;
1402 }
1403
1404
1405 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1406 if (must_throttle_split_if()) {
1407 return false;
1408 }
1409
1410 // Do not do 'split-if' if irreducible loops are present.
1411 if (_has_irreducible_loops) {
1412 return false;
1413 }
1414
1415 if (merge_point_too_heavy(C, n_ctrl)) {
1416 return false;
1417 }
1418
1419 // Do not do 'split-if' if some paths are dead. First do dead code
1420 // elimination and then see if its still profitable.
1421 for (uint i = 1; i < n_ctrl->req(); i++) {
1422 if (n_ctrl->in(i) == C->top()) {
1423 return false;
1424 }
1425 }
1426
1427 // If trying to do a 'Split-If' at the loop head, it is only
1428 // profitable if the cmp folds up on BOTH paths. Otherwise we
1429 // risk peeling a loop forever.
1430
1431 // CNC - Disabled for now. Requires careful handling of loop
1432 // body selection for the cloned code. Also, make sure we check
1433 // for any input path not being in the same loop as n_ctrl. For
1434 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1435 // because the alternative loop entry points won't be converted
1436 // into LoopNodes.
1437 IdealLoopTree *n_loop = get_loop(n_ctrl);
1438 for (uint j = 1; j < n_ctrl->req(); j++) {
1439 if (get_loop(n_ctrl->in(j)) != n_loop) {
1440 return false;
1441 }
1442 }
1443
1444 // Check for safety of the merge point.
1445 if (!merge_point_safe(n_ctrl)) {
1446 return false;
1447 }
1448
1449 return true;
1450 }
1451
1452 // Detect if the node is the inner strip-mined loop
1453 // Return: null if it's not the case, or the exit of outer strip-mined loop
1454 static Node* is_inner_of_stripmined_loop(const Node* out) {
1455 Node* out_le = nullptr;
1456
1457 if (out->is_CountedLoopEnd()) {
1458 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1459
1460 if (loop != nullptr && loop->is_strip_mined()) {
1461 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1462 }
1463 }
1464
1465 return out_le;
1466 }
1467
1468 bool PhaseIdealLoop::flat_array_element_type_check(Node *n) {
1469 // If the CmpP is a subtype check for a value that has just been
1470 // loaded from an array, the subtype check guarantees the value
1471 // can't be stored in a flat array and the load of the value
1472 // happens with a flat array check then: push the type check
1473 // through the phi of the flat array check. This needs special
1474 // logic because the subtype check's input is not a phi but a
1475 // LoadKlass that must first be cloned through the phi.
1476 if (n->Opcode() != Op_CmpP) {
1477 return false;
1478 }
1479
1480 Node* klassptr = n->in(1);
1481 Node* klasscon = n->in(2);
1482
1483 if (klassptr->is_DecodeNarrowPtr()) {
1484 klassptr = klassptr->in(1);
1485 }
1486
1487 if (klassptr->Opcode() != Op_LoadKlass && klassptr->Opcode() != Op_LoadNKlass) {
1488 return false;
1489 }
1490
1491 if (!klasscon->is_Con()) {
1492 return false;
1493 }
1494
1495 Node* addr = klassptr->in(MemNode::Address);
1496
1497 if (!addr->is_AddP()) {
1498 return false;
1499 }
1500
1501 intptr_t offset;
1502 Node* obj = AddPNode::Ideal_base_and_offset(addr, &_igvn, offset);
1503
1504 if (obj == nullptr) {
1505 return false;
1506 }
1507
1508 // TODO 8378077: The code below does not work anymore with off-heap accesses which set their bases to top with
1509 // JDK-8373343. Also: flat_array_element_type_check() was introduced with JDK-8228622 for a specific check to enable
1510 // split-if but JDK-8245729 changed how that check looks like. Is it still relevant? This should be revisited.
1511 if (addr->in(AddPNode::Base)->is_top()) {
1512 return false;
1513 }
1514
1515 if (obj->Opcode() == Op_CastPP) {
1516 obj = obj->in(1);
1517 }
1518
1519 if (!obj->is_Phi()) {
1520 return false;
1521 }
1522
1523 Node* region = obj->in(0);
1524
1525 Node* phi = PhiNode::make_blank(region, n->in(1));
1526 for (uint i = 1; i < region->req(); i++) {
1527 Node* in = obj->in(i);
1528 Node* ctrl = region->in(i);
1529 if (addr->in(AddPNode::Base) != obj) {
1530 Node* cast = addr->in(AddPNode::Base);
1531 assert(cast->Opcode() == Op_CastPP && cast->in(0) != nullptr, "inconsistent subgraph");
1532 Node* cast_clone = cast->clone();
1533 cast_clone->set_req(0, ctrl);
1534 cast_clone->set_req(1, in);
1535 register_new_node(cast_clone, ctrl);
1536 const Type* tcast = cast_clone->Value(&_igvn);
1537 _igvn.set_type(cast_clone, tcast);
1538 cast_clone->as_Type()->set_type(tcast);
1539 in = cast_clone;
1540 }
1541 Node* addr_clone = addr->clone();
1542 addr_clone->set_req(AddPNode::Base, in);
1543 addr_clone->set_req(AddPNode::Address, in);
1544 register_new_node(addr_clone, ctrl);
1545 _igvn.set_type(addr_clone, addr_clone->Value(&_igvn));
1546 Node* klassptr_clone = klassptr->clone();
1547 klassptr_clone->set_req(2, addr_clone);
1548 register_new_node(klassptr_clone, ctrl);
1549 _igvn.set_type(klassptr_clone, klassptr_clone->Value(&_igvn));
1550 if (klassptr != n->in(1)) {
1551 Node* decode = n->in(1);
1552 assert(decode->is_DecodeNarrowPtr(), "inconsistent subgraph");
1553 Node* decode_clone = decode->clone();
1554 decode_clone->set_req(1, klassptr_clone);
1555 register_new_node(decode_clone, ctrl);
1556 _igvn.set_type(decode_clone, decode_clone->Value(&_igvn));
1557 klassptr_clone = decode_clone;
1558 }
1559 phi->set_req(i, klassptr_clone);
1560 }
1561 register_new_node(phi, region);
1562 Node* orig = n->in(1);
1563 _igvn.replace_input_of(n, 1, phi);
1564 split_if_with_blocks_post(n);
1565 if (n->outcnt() != 0) {
1566 _igvn.replace_input_of(n, 1, orig);
1567 _igvn.remove_dead_node(phi, PhaseIterGVN::NodeOrigin::Graph);
1568 }
1569 return true;
1570 }
1571
1572 //------------------------------split_if_with_blocks_post----------------------
1573 // Do the real work in a non-recursive function. CFG hackery wants to be
1574 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1575 // info.
1576 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1577
1578 if (flat_array_element_type_check(n)) {
1579 return;
1580 }
1581
1582 // Cloning Cmp through Phi's involves the split-if transform.
1583 // FastLock is not used by an If
1584 if (n->is_Cmp() && !n->is_FastLock()) {
1585 Node *n_ctrl = get_ctrl(n);
1586 // Determine if the Node has inputs from some local Phi.
1587 // Returns the block to clone thru.
1588 Node *n_blk = has_local_phi_input(n);
1589 if (n_blk != n_ctrl) {
1590 return;
1591 }
1592
1593 if (!can_split_if(n_ctrl)) {
1594 return;
1595 }
1596
1597 if (n->outcnt() != 1) {
1598 return; // Multiple bool's from 1 compare?
1599 }
1600 Node *bol = n->unique_out();
1601 assert(bol->is_Bool(), "expect a bool here");
1602 if (bol->outcnt() != 1) {
1603 return;// Multiple branches from 1 compare?
1604 }
1605 Node *iff = bol->unique_out();
1606
1607 // Check some safety conditions
1608 if (iff->is_If()) { // Classic split-if?
1609 if (iff->in(0) != n_ctrl) {
1610 return; // Compare must be in same blk as if
1611 }
1612 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1613 // Can't split CMove with different control.
1614 if (get_ctrl(iff) != n_ctrl) {
1615 return;
1616 }
1617 if (get_ctrl(iff->in(2)) == n_ctrl ||
1618 get_ctrl(iff->in(3)) == n_ctrl) {
1619 return; // Inputs not yet split-up
1620 }
1621 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1622 return; // Loop-invar test gates loop-varying CMOVE
1623 }
1624 } else {
1625 return; // some other kind of node, such as an Allocate
1626 }
1627
1628 // When is split-if profitable? Every 'win' on means some control flow
1629 // goes dead, so it's almost always a win.
1630 int policy = 0;
1631 // Split compare 'n' through the merge point if it is profitable
1632 Node *phi = split_thru_phi( n, n_ctrl, policy);
1633 if (!phi) {
1634 return;
1635 }
1636
1637 // Now split the bool up thru the phi
1638 Node* bolphi = split_thru_phi(bol, n_ctrl, -1);
1639 guarantee(bolphi != nullptr, "null boolean phi node");
1640 assert(iff->in(1) == bolphi, "");
1641
1642 if (bolphi->Value(&_igvn)->singleton()) {
1643 return;
1644 }
1645
1646 // Conditional-move? Must split up now
1647 if (!iff->is_If()) {
1648 Node* cmovphi = split_thru_phi(iff, n_ctrl, -1);
1649 return;
1650 }
1651
1652 // Now split the IF
1653 C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1654 #ifndef PRODUCT
1655 if (TraceLoopOpts || TraceSplitIf) {
1656 tty->print_cr("Split-If: %d %s", iff->_idx, iff->Name());
1657 }
1658 #endif
1659 do_split_if(iff);
1660 C->print_method(PHASE_AFTER_SPLIT_IF, 4, iff);
1661 return;
1662 }
1663
1664 // Two identical ifs back to back can be merged
1665 if (try_merge_identical_ifs(n)) {
1666 return;
1667 }
1668
1669 // Check for an IF ready to split; one that has its
1670 // condition codes input coming from a Phi at the block start.
1671 int n_op = n->Opcode();
1672
1673 // Check for an IF being dominated by another IF same test
1674 if (n_op == Op_If ||
1675 n_op == Op_RangeCheck) {
1676 Node *bol = n->in(1);
1677 uint max = bol->outcnt();
1678 // Check for same test used more than once?
1679 if (bol->is_Bool() && (max > 1 || bol->in(1)->is_SubTypeCheck())) {
1680 // Search up IDOMs to see if this IF is dominated.
1681 Node* cmp = bol->in(1);
1682 Node *cutoff = cmp->is_SubTypeCheck() ? dom_lca(get_ctrl(cmp->in(1)), get_ctrl(cmp->in(2))) : get_ctrl(bol);
1683
1684 // Now search up IDOMs till cutoff, looking for a dominating test
1685 Node *prevdom = n;
1686 Node *dom = idom(prevdom);
1687 while (dom != cutoff) {
1688 if (dom->req() > 1 && n->as_If()->same_condition(dom, &_igvn) && prevdom->in(0) == dom &&
1689 safe_for_if_replacement(dom)) {
1690 // It's invalid to move control dependent data nodes in the inner
1691 // strip-mined loop, because:
1692 // 1) break validation of LoopNode::verify_strip_mined()
1693 // 2) move code with side-effect in strip-mined loop
1694 // Move to the exit of outer strip-mined loop in that case.
1695 Node* out_le = is_inner_of_stripmined_loop(dom);
1696 if (out_le != nullptr) {
1697 prevdom = out_le;
1698 }
1699 // Replace the dominated test with an obvious true or false.
1700 // Place it on the IGVN worklist for later cleanup.
1701 C->set_major_progress();
1702 // Split if: pin array accesses that are control dependent on a range check and moved to a regular if,
1703 // to prevent an array load from floating above its range check. There are three cases:
1704 // 1. Move from RangeCheck "a" to RangeCheck "b": don't need to pin. If we ever remove b, then we pin
1705 // all its array accesses at that point.
1706 // 2. We move from RangeCheck "a" to regular if "b": need to pin. If we ever remove b, then its array
1707 // accesses would start to float, since we don't pin at that point.
1708 // 3. If we move from regular if: don't pin. All array accesses are already assumed to be pinned.
1709 bool pin_array_access_nodes = n->Opcode() == Op_RangeCheck &&
1710 prevdom->in(0)->Opcode() != Op_RangeCheck;
1711 dominated_by(prevdom->as_IfProj(), n->as_If(), false, pin_array_access_nodes);
1712 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1713 return;
1714 }
1715 prevdom = dom;
1716 dom = idom(prevdom);
1717 }
1718 }
1719 }
1720
1721 try_sink_out_of_loop(n);
1722 if (C->failing()) {
1723 return;
1724 }
1725
1726 try_move_store_after_loop(n);
1727
1728 // Remove multiple allocations of the same inline type
1729 if (n->is_InlineType()) {
1730 n->as_InlineType()->remove_redundant_allocations(this);
1731 }
1732 }
1733
1734 // Transform:
1735 //
1736 // if (some_condition) {
1737 // // body 1
1738 // } else {
1739 // // body 2
1740 // }
1741 // if (some_condition) {
1742 // // body 3
1743 // } else {
1744 // // body 4
1745 // }
1746 //
1747 // into:
1748 //
1749 //
1750 // if (some_condition) {
1751 // // body 1
1752 // // body 3
1753 // } else {
1754 // // body 2
1755 // // body 4
1756 // }
1757 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1758 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1759 Node *n_ctrl = n->in(0);
1760 IfNode* dom_if = idom(n_ctrl)->as_If();
1761 if (n->in(1) != dom_if->in(1)) {
1762 assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1763 (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1764 dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1765 _igvn.replace_input_of(n, 1, dom_if->in(1));
1766 }
1767 IfTrueNode* dom_proj_true = dom_if->true_proj();
1768 IfFalseNode* dom_proj_false = dom_if->false_proj();
1769
1770 // Now split the IF
1771 RegionNode* new_false_region;
1772 RegionNode* new_true_region;
1773 #ifndef PRODUCT
1774 if (TraceLoopOpts || TraceSplitIf) {
1775 tty->print_cr("Split-If Merging Identical Ifs: Dom-If: %d %s, If: %d %s", dom_if->_idx, dom_if->Name(), n->_idx, n->Name());
1776 }
1777 #endif
1778 do_split_if(n, &new_false_region, &new_true_region);
1779 assert(new_false_region->req() == new_true_region->req(), "");
1780 #ifdef ASSERT
1781 for (uint i = 1; i < new_false_region->req(); ++i) {
1782 assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1783 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");
1784 }
1785 #endif
1786 assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1787
1788 // We now have:
1789 // if (some_condition) {
1790 // // body 1
1791 // if (some_condition) {
1792 // body3: // new_true_region
1793 // // body3
1794 // } else {
1795 // goto body4;
1796 // }
1797 // } else {
1798 // // body 2
1799 // if (some_condition) {
1800 // goto body3;
1801 // } else {
1802 // body4: // new_false_region
1803 // // body4;
1804 // }
1805 // }
1806 //
1807
1808 // clone pinned nodes thru the resulting regions
1809 push_pinned_nodes_thru_region(dom_if, new_true_region);
1810 push_pinned_nodes_thru_region(dom_if, new_false_region);
1811
1812 // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1813 // 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
1814 // unrelated control dependency.
1815 for (uint i = 1; i < new_false_region->req(); i++) {
1816 if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1817 dominated_by(dom_proj_true, new_false_region->in(i)->in(0)->as_If());
1818 } else {
1819 assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1820 dominated_by(dom_proj_false, new_false_region->in(i)->in(0)->as_If());
1821 }
1822 }
1823 return true;
1824 }
1825 return false;
1826 }
1827
1828 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1829 for (DUIterator i = region->outs(); region->has_out(i); i++) {
1830 Node* u = region->out(i);
1831 if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test()) {
1832 continue;
1833 }
1834 assert(u->in(0) == region, "not a control dependent node?");
1835 uint j = 1;
1836 for (; j < u->req(); ++j) {
1837 Node* in = u->in(j);
1838 if (!is_dominator(ctrl_or_self(in), dom_if)) {
1839 break;
1840 }
1841 }
1842 if (j == u->req()) {
1843 Node *phi = PhiNode::make_blank(region, u);
1844 for (uint k = 1; k < region->req(); ++k) {
1845 Node* clone = u->clone();
1846 clone->set_req(0, region->in(k));
1847 register_new_node(clone, region->in(k));
1848 phi->init_req(k, clone);
1849 }
1850 register_new_node(phi, region);
1851 _igvn.replace_node(u, phi);
1852 --i;
1853 }
1854 }
1855 }
1856
1857 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1858 if (!dom->is_CountedLoopEnd()) {
1859 return true;
1860 }
1861 CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1862 CountedLoopNode* cl = le->loopnode();
1863 if (cl == nullptr) {
1864 return true;
1865 }
1866 if (!cl->is_main_loop()) {
1867 return true;
1868 }
1869 if (cl->is_canonical_loop_entry() == nullptr) {
1870 return true;
1871 }
1872 // Further unrolling is possible so loop exit condition might change
1873 return false;
1874 }
1875
1876 // See if a shared loop-varying computation has no loop-varying uses.
1877 // Happens if something is only used for JVM state in uncommon trap exits,
1878 // like various versions of induction variable+offset. Clone the
1879 // computation per usage to allow it to sink out of the loop.
1880 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1881 bool is_raw_to_oop_cast = n->is_ConstraintCast() &&
1882 n->in(1)->bottom_type()->isa_rawptr() &&
1883 !n->bottom_type()->isa_rawptr();
1884
1885 if (has_ctrl(n) &&
1886 !n->is_Phi() &&
1887 !n->is_Bool() &&
1888 !n->is_Proj() &&
1889 !n->is_MergeMem() &&
1890 !n->is_CMove() &&
1891 !n->is_OpaqueConstantBool() &&
1892 !n->is_OpaqueInitializedAssertionPredicate() &&
1893 !n->is_OpaqueTemplateAssertionPredicate() &&
1894 !is_raw_to_oop_cast && // don't extend live ranges of raw oops
1895 n->Opcode() != Op_CreateEx &&
1896 (KillPathsReachableByDeadTypeNode || !n->is_Type())
1897 ) {
1898 Node *n_ctrl = get_ctrl(n);
1899 IdealLoopTree *n_loop = get_loop(n_ctrl);
1900
1901 if (n->in(0) != nullptr) {
1902 IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1903 if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1904 // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1905 // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1906 // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1907 Node* maybe_pinned_n = n;
1908 Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1909 if (!would_sink_below_pre_loop_exit(loop_ctrl, outside_ctrl)) {
1910 if (n->depends_only_on_test()) {
1911 // If this node depends_only_on_test, it will be rewired to a control input that is not
1912 // the correct test. As a result, it must be pinned otherwise it can be incorrectly
1913 // rewired to a dominating test equivalent to the new control.
1914 Node* pinned_clone = n->pin_node_under_control();
1915 if (pinned_clone != nullptr) {
1916 register_new_node(pinned_clone, n_ctrl);
1917 maybe_pinned_n = pinned_clone;
1918 _igvn.replace_node(n, pinned_clone);
1919 }
1920 }
1921 _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1922 }
1923 }
1924 }
1925 if (n_loop != _ltree_root && n->outcnt() > 1) {
1926 // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1927 // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1928 Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1929 if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1930 ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1931 if (n->is_Store() || n->is_LoadStore()) {
1932 assert(false, "no node with a side effect");
1933 C->record_failure("no node with a side effect");
1934 return;
1935 }
1936 Node* outer_loop_clone = nullptr;
1937 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1938 Node* u = n->last_out(j); // Clone private computation per use
1939 _igvn.rehash_node_delayed(u);
1940 Node* x = nullptr;
1941 if (n->in(0) != nullptr && n->depends_only_on_test()) {
1942 // If this node depends_only_on_test, it will be rewired to a control input that is not
1943 // the correct test. As a result, it must be pinned otherwise it can be incorrectly
1944 // rewired to a dominating test equivalent to the new control.
1945 x = n->pin_node_under_control();
1946 }
1947 if (x == nullptr) {
1948 x = n->clone();
1949 }
1950 Node* x_ctrl = nullptr;
1951 if (u->is_Phi()) {
1952 // Replace all uses of normal nodes. Replace Phi uses
1953 // individually, so the separate Nodes can sink down
1954 // different paths.
1955 uint k = 1;
1956 while (u->in(k) != n) k++;
1957 u->set_req(k, x);
1958 // x goes next to Phi input path
1959 x_ctrl = u->in(0)->in(k);
1960 // Find control for 'x' next to use but not inside inner loops.
1961 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1962 --j;
1963 } else { // Normal use
1964 if (has_ctrl(u)) {
1965 x_ctrl = get_ctrl(u);
1966 } else {
1967 x_ctrl = u->in(0);
1968 }
1969 // Find control for 'x' next to use but not inside inner loops.
1970 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1971 // Replace all uses
1972 if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1973 // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1974 // anymore now that we're going to pin n as well
1975 _igvn.replace_node(u, x);
1976 --j;
1977 } else {
1978 int nb = u->replace_edge(n, x, &_igvn);
1979 j -= nb;
1980 }
1981 }
1982
1983 if (n->is_Load()) {
1984 // For loads, add a control edge to a CFG node outside of the loop
1985 // to force them to not combine and return back inside the loop
1986 // during GVN optimization (4641526).
1987 assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1988
1989 IdealLoopTree* x_loop = get_loop(x_ctrl);
1990 Node* x_head = x_loop->_head;
1991 if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1992 // Do not add duplicate LoadNodes to the outer strip mined loop
1993 if (outer_loop_clone != nullptr) {
1994 _igvn.replace_node(x, outer_loop_clone);
1995 continue;
1996 }
1997 outer_loop_clone = x;
1998 }
1999 x->set_req(0, x_ctrl);
2000 } else if (n->in(0) != nullptr){
2001 x->set_req(0, x_ctrl);
2002 }
2003 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
2004 assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
2005 register_new_node(x, x_ctrl);
2006
2007 // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
2008 // All AddP nodes must keep the same base after sinking so:
2009 // 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,
2010 // their bases remain the same.
2011 // (see 2- below)
2012 assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
2013 x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
2014 !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
2015 if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
2016 !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
2017 assert(!x->is_Load(), "load should be pinned");
2018 // Use a cast node to pin clone out of loop
2019 Node* cast = nullptr;
2020 for (uint k = 0; k < x->req(); k++) {
2021 Node* in = x->in(k);
2022 if (in != nullptr && ctrl_is_member(n_loop, in)) {
2023 const Type* in_t = _igvn.type(in);
2024 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
2025 ConstraintCastNode::DependencyType::NonFloatingNonNarrowing, nullptr);
2026 }
2027 if (cast != nullptr) {
2028 Node* prev = _igvn.hash_find_insert(cast);
2029 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
2030 cast->destruct(&_igvn);
2031 cast = prev;
2032 } else {
2033 register_new_node(cast, x_ctrl);
2034 }
2035 x->replace_edge(in, cast);
2036 // Chain of AddP nodes:
2037 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
2038 if (x->is_AddP() && k == AddPNode::Base) {
2039 update_addp_chain_base(x, n->in(AddPNode::Base), cast);
2040 }
2041 break;
2042 }
2043 }
2044 assert(cast != nullptr, "must have added a cast to pin the node");
2045 }
2046 }
2047 _igvn.remove_dead_node(n, PhaseIterGVN::NodeOrigin::Graph);
2048 }
2049 _dom_lca_tags_round = 0;
2050 }
2051 }
2052 }
2053
2054 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
2055 ResourceMark rm;
2056 Node_List wq;
2057 wq.push(x);
2058 while (wq.size() != 0) {
2059 Node* n = wq.pop();
2060 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2061 Node* u = n->fast_out(i);
2062 if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
2063 _igvn.replace_input_of(u, AddPNode::Base, new_base);
2064 wq.push(u);
2065 }
2066 }
2067 }
2068 }
2069
2070 // Compute the early control of a node by following its inputs until we reach
2071 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
2072 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
2073 Node* early_ctrl = nullptr;
2074 ResourceMark rm;
2075 Unique_Node_List wq;
2076 wq.push(n);
2077 for (uint i = 0; i < wq.size(); i++) {
2078 Node* m = wq.at(i);
2079 Node* c = nullptr;
2080 if (m->is_CFG()) {
2081 c = m;
2082 } else if (m->pinned()) {
2083 c = m->in(0);
2084 } else {
2085 for (uint j = 0; j < m->req(); j++) {
2086 Node* in = m->in(j);
2087 if (in != nullptr) {
2088 wq.push(in);
2089 }
2090 }
2091 }
2092 if (c != nullptr) {
2093 assert(is_dominator(c, n_ctrl), "control input must dominate current control");
2094 if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
2095 early_ctrl = c;
2096 }
2097 }
2098 }
2099 assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
2100 return early_ctrl;
2101 }
2102
2103 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
2104 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2105 Node* u = n->fast_out(i);
2106 if (u->is_Opaque1()) {
2107 return false; // Found loop limit, bugfix for 4677003
2108 }
2109 if (u->is_Phi()) {
2110 for (uint j = 1; j < u->req(); ++j) {
2111 if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
2112 return false;
2113 }
2114 }
2115 } else {
2116 Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
2117 if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
2118 return false;
2119 }
2120 }
2121 }
2122 return true;
2123 }
2124
2125 // 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
2126 // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
2127 // test of the pre loop above the point in the graph where it's pinned. This results in a broken graph. One way to avoid
2128 // it would be to not eliminate the check in the main loop. Instead, we prevent sinking of the node here so better code
2129 // is generated for the main loop.
2130 bool PhaseIdealLoop::would_sink_below_pre_loop_exit(IdealLoopTree* n_loop, Node* ctrl) {
2131 if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
2132 CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
2133 if (is_dominator(pre_loop->loopexit(), ctrl)) {
2134 return true;
2135 }
2136 }
2137 return false;
2138 }
2139
2140 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
2141 if (n->is_Load()) {
2142 // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure each call to
2143 // get_late_ctrl_with_anti_dep() uses its own tag
2144 _dom_lca_tags_round++;
2145 assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
2146
2147 ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
2148 }
2149 IdealLoopTree *u_loop = get_loop(ctrl);
2150 if (u_loop == n_loop) {
2151 return false; // Found loop-varying use
2152 }
2153 if (n_loop->is_member(u_loop)) {
2154 return false; // Found use in inner loop
2155 }
2156 if (would_sink_below_pre_loop_exit(n_loop, ctrl)) {
2157 return false;
2158 }
2159 return true;
2160 }
2161
2162 //------------------------------split_if_with_blocks---------------------------
2163 // Check for aggressive application of 'split-if' optimization,
2164 // using basic block level info.
2165 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
2166 Node* root = C->root();
2167 visited.set(root->_idx); // first, mark root as visited
2168 // Do pre-visit work for root
2169 Node* n = split_if_with_blocks_pre(root);
2170 uint cnt = n->outcnt();
2171 uint i = 0;
2172
2173 while (true) {
2174 // Visit all children
2175 if (i < cnt) {
2176 Node* use = n->raw_out(i);
2177 ++i;
2178 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
2179 // Now do pre-visit work for this use
2180 use = split_if_with_blocks_pre(use);
2181 nstack.push(n, i); // Save parent and next use's index.
2182 n = use; // Process all children of current use.
2183 cnt = use->outcnt();
2184 i = 0;
2185 }
2186 }
2187 else {
2188 // All of n's children have been processed, complete post-processing.
2189 if (cnt != 0 && !n->is_Con()) {
2190 assert(has_node(n), "no dead nodes");
2191 split_if_with_blocks_post(n);
2192 if (C->failing()) {
2193 return;
2194 }
2195 }
2196 if (must_throttle_split_if()) {
2197 nstack.clear();
2198 }
2199 if (nstack.is_empty()) {
2200 // Finished all nodes on stack.
2201 break;
2202 }
2203 // Get saved parent node and next use's index. Visit the rest of uses.
2204 n = nstack.node();
2205 cnt = n->outcnt();
2206 i = nstack.index();
2207 nstack.pop();
2208 }
2209 }
2210 }
2211
2212
2213 //=============================================================================
2214 //
2215 // C L O N E A L O O P B O D Y
2216 //
2217
2218 //------------------------------clone_iff--------------------------------------
2219 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2220 // "Nearly" because all Nodes have been cloned from the original in the loop,
2221 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2222 // through the Phi recursively, and return a Bool.
2223 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2224
2225 // Convert this Phi into a Phi merging Bools
2226 uint i;
2227 for (i = 1; i < phi->req(); i++) {
2228 Node* b = phi->in(i);
2229 if (b->is_Phi()) {
2230 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2231 } else {
2232 assert(b->is_Bool() || b->is_OpaqueConstantBool() || b->is_OpaqueInitializedAssertionPredicate(),
2233 "bool, non-null check with OpaqueConstantBool or Initialized Assertion Predicate with its Opaque node");
2234 }
2235 }
2236 Node* n = phi->in(1);
2237 Node* sample_opaque = nullptr;
2238 Node *sample_bool = nullptr;
2239 if (n->is_OpaqueConstantBool() || n->is_OpaqueInitializedAssertionPredicate()) {
2240 sample_opaque = n;
2241 sample_bool = n->in(1);
2242 assert(sample_bool->is_Bool(), "wrong type");
2243 } else {
2244 sample_bool = n;
2245 }
2246 Node* sample_cmp = sample_bool->in(1);
2247 const Type* t = Type::TOP;
2248 const TypePtr* at = nullptr;
2249 if (sample_cmp->is_FlatArrayCheck()) {
2250 // Left input of a FlatArrayCheckNode is memory, set the (adr) type of the phi accordingly
2251 assert(sample_cmp->in(1)->bottom_type() == Type::MEMORY, "unexpected input type");
2252 t = Type::MEMORY;
2253 at = TypeRawPtr::BOTTOM;
2254 }
2255
2256 // Make Phis to merge the Cmp's inputs.
2257 PhiNode *phi1 = new PhiNode(phi->in(0), t, at);
2258 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2259 for (i = 1; i < phi->req(); i++) {
2260 Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2261 Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2262 phi1->set_req(i, n1);
2263 phi2->set_req(i, n2);
2264 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2265 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2266 }
2267 // See if these Phis have been made before.
2268 // Register with optimizer
2269 Node *hit1 = _igvn.hash_find_insert(phi1);
2270 if (hit1) { // Hit, toss just made Phi
2271 _igvn.remove_dead_node(phi1, PhaseIterGVN::NodeOrigin::Speculative); // Remove new phi
2272 assert(hit1->is_Phi(), "" );
2273 phi1 = (PhiNode*)hit1; // Use existing phi
2274 } else { // Miss
2275 _igvn.register_new_node_with_optimizer(phi1);
2276 }
2277 Node *hit2 = _igvn.hash_find_insert(phi2);
2278 if (hit2) { // Hit, toss just made Phi
2279 _igvn.remove_dead_node(phi2, PhaseIterGVN::NodeOrigin::Speculative); // Remove new phi
2280 assert(hit2->is_Phi(), "" );
2281 phi2 = (PhiNode*)hit2; // Use existing phi
2282 } else { // Miss
2283 _igvn.register_new_node_with_optimizer(phi2);
2284 }
2285 // Register Phis with loop/block info
2286 set_ctrl(phi1, phi->in(0));
2287 set_ctrl(phi2, phi->in(0));
2288 // Make a new Cmp
2289 Node *cmp = sample_cmp->clone();
2290 cmp->set_req(1, phi1);
2291 cmp->set_req(2, phi2);
2292 _igvn.register_new_node_with_optimizer(cmp);
2293 set_ctrl(cmp, phi->in(0));
2294
2295 // Make a new Bool
2296 Node *b = sample_bool->clone();
2297 b->set_req(1,cmp);
2298 _igvn.register_new_node_with_optimizer(b);
2299 set_ctrl(b, phi->in(0));
2300
2301 if (sample_opaque != nullptr) {
2302 Node* opaque = sample_opaque->clone();
2303 opaque->set_req(1, b);
2304 _igvn.register_new_node_with_optimizer(opaque);
2305 set_ctrl(opaque, phi->in(0));
2306 return opaque;
2307 }
2308
2309 assert(b->is_Bool(), "");
2310 return b;
2311 }
2312
2313 //------------------------------clone_bool-------------------------------------
2314 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2315 // "Nearly" because all Nodes have been cloned from the original in the loop,
2316 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2317 // through the Phi recursively, and return a Bool.
2318 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2319 uint i;
2320 // Convert this Phi into a Phi merging Bools
2321 for( i = 1; i < phi->req(); i++ ) {
2322 Node *b = phi->in(i);
2323 if( b->is_Phi() ) {
2324 _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2325 } else {
2326 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2327 }
2328 }
2329
2330 Node *sample_cmp = phi->in(1);
2331
2332 // Make Phis to merge the Cmp's inputs.
2333 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2334 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2335 for( uint j = 1; j < phi->req(); j++ ) {
2336 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2337 Node *n1, *n2;
2338 if( cmp_top->is_Cmp() ) {
2339 n1 = cmp_top->in(1);
2340 n2 = cmp_top->in(2);
2341 } else {
2342 n1 = n2 = cmp_top;
2343 }
2344 phi1->set_req( j, n1 );
2345 phi2->set_req( j, n2 );
2346 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2347 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2348 }
2349
2350 // See if these Phis have been made before.
2351 // Register with optimizer
2352 Node *hit1 = _igvn.hash_find_insert(phi1);
2353 if( hit1 ) { // Hit, toss just made Phi
2354 _igvn.remove_dead_node(phi1, PhaseIterGVN::NodeOrigin::Speculative); // Remove new phi
2355 assert( hit1->is_Phi(), "" );
2356 phi1 = (PhiNode*)hit1; // Use existing phi
2357 } else { // Miss
2358 _igvn.register_new_node_with_optimizer(phi1);
2359 }
2360 Node *hit2 = _igvn.hash_find_insert(phi2);
2361 if( hit2 ) { // Hit, toss just made Phi
2362 _igvn.remove_dead_node(phi2, PhaseIterGVN::NodeOrigin::Speculative); // Remove new phi
2363 assert( hit2->is_Phi(), "" );
2364 phi2 = (PhiNode*)hit2; // Use existing phi
2365 } else { // Miss
2366 _igvn.register_new_node_with_optimizer(phi2);
2367 }
2368 // Register Phis with loop/block info
2369 set_ctrl(phi1, phi->in(0));
2370 set_ctrl(phi2, phi->in(0));
2371 // Make a new Cmp
2372 Node *cmp = sample_cmp->clone();
2373 cmp->set_req( 1, phi1 );
2374 cmp->set_req( 2, phi2 );
2375 _igvn.register_new_node_with_optimizer(cmp);
2376 set_ctrl(cmp, phi->in(0));
2377
2378 assert( cmp->is_Cmp(), "" );
2379 return (CmpNode*)cmp;
2380 }
2381
2382 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2383 IdealLoopTree* loop, IdealLoopTree* outer_loop,
2384 Node_List*& split_if_set, Node_List*& split_bool_set,
2385 Node_List*& split_cex_set, Node_List& worklist,
2386 uint new_counter, CloneLoopMode mode) {
2387 Node* nnn = old_new[old->_idx];
2388 // Copy uses to a worklist, so I can munge the def-use info
2389 // with impunity.
2390 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2391 worklist.push(old->fast_out(j));
2392
2393 while( worklist.size() ) {
2394 Node *use = worklist.pop();
2395 if (!has_node(use)) continue; // Ignore dead nodes
2396 if (use->in(0) == C->top()) continue;
2397 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2398 // Check for data-use outside of loop - at least one of OLD or USE
2399 // must not be a CFG node.
2400 #ifdef ASSERT
2401 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2402 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2403 assert(mode != IgnoreStripMined, "incorrect cloning mode");
2404 assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2405 }
2406 #endif
2407 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2408
2409 // If the Data use is an IF, that means we have an IF outside the
2410 // loop that is switching on a condition that is set inside the
2411 // loop. Happens if people set a loop-exit flag; then test the flag
2412 // in the loop to break the loop, then test is again outside the
2413 // loop to determine which way the loop exited.
2414 //
2415 // For several uses we need to make sure that there is no phi between,
2416 // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2417 // to avoid such a phi in between.
2418 // For example, it is unexpected that there is a Phi between an
2419 // AllocateArray node and its ValidLengthTest input that could cause
2420 // split if to break.
2421 assert(!use->is_OpaqueTemplateAssertionPredicate(),
2422 "should not clone a Template Assertion Predicate which should be removed once it's useless");
2423 if (use->is_If() || use->is_CMove() || use->is_OpaqueConstantBool() || use->is_OpaqueInitializedAssertionPredicate() ||
2424 (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2425 // Since this code is highly unlikely, we lazily build the worklist
2426 // of such Nodes to go split.
2427 if (!split_if_set) {
2428 split_if_set = new Node_List();
2429 }
2430 split_if_set->push(use);
2431 }
2432 if (use->is_Bool()) {
2433 if (!split_bool_set) {
2434 split_bool_set = new Node_List();
2435 }
2436 split_bool_set->push(use);
2437 }
2438 if (use->Opcode() == Op_CreateEx) {
2439 if (!split_cex_set) {
2440 split_cex_set = new Node_List();
2441 }
2442 split_cex_set->push(use);
2443 }
2444
2445
2446 // Get "block" use is in
2447 uint idx = 0;
2448 while( use->in(idx) != old ) idx++;
2449 Node *prev = use->is_CFG() ? use : get_ctrl(use);
2450 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2451 Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2452 ? prev->in(2)
2453 : idom(prev);
2454 if( use->is_Phi() ) // Phi use is in prior block
2455 cfg = prev->in(idx); // NOT in block of Phi itself
2456 if (cfg->is_top()) { // Use is dead?
2457 _igvn.replace_input_of(use, idx, C->top());
2458 continue;
2459 }
2460
2461 // If use is referenced through control edge... (idx == 0)
2462 if (mode == IgnoreStripMined && idx == 0) {
2463 LoopNode *head = loop->_head->as_Loop();
2464 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2465 // That node is outside the inner loop, leave it outside the
2466 // outer loop as well to not confuse verification code.
2467 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2468 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2469 continue;
2470 }
2471 }
2472
2473 while(!outer_loop->is_member(get_loop(cfg))) {
2474 prev = cfg;
2475 cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2476 }
2477 // If the use occurs after merging several exits from the loop, then
2478 // old value must have dominated all those exits. Since the same old
2479 // value was used on all those exits we did not need a Phi at this
2480 // merge point. NOW we do need a Phi here. Each loop exit value
2481 // is now merged with the peeled body exit; each exit gets its own
2482 // private Phi and those Phis need to be merged here.
2483 Node *phi;
2484 if( prev->is_Region() ) {
2485 if( idx == 0 ) { // Updating control edge?
2486 phi = prev; // Just use existing control
2487 } else { // Else need a new Phi
2488 phi = PhiNode::make( prev, old );
2489 // Now recursively fix up the new uses of old!
2490 for( uint i = 1; i < prev->req(); i++ ) {
2491 worklist.push(phi); // Onto worklist once for each 'old' input
2492 }
2493 }
2494 } else {
2495 // Get new RegionNode merging old and new loop exits
2496 prev = old_new[prev->_idx];
2497 assert( prev, "just made this in step 7" );
2498 if( idx == 0) { // Updating control edge?
2499 phi = prev; // Just use existing control
2500 } else { // Else need a new Phi
2501 // Make a new Phi merging data values properly
2502 phi = PhiNode::make( prev, old );
2503 phi->set_req( 1, nnn );
2504 }
2505 }
2506 // If inserting a new Phi, check for prior hits
2507 if( idx != 0 ) {
2508 Node *hit = _igvn.hash_find_insert(phi);
2509 if( hit == nullptr ) {
2510 _igvn.register_new_node_with_optimizer(phi); // Register new phi
2511 } else { // or
2512 // Remove the new phi from the graph and use the hit
2513 _igvn.remove_dead_node(phi, phi == prev ? PhaseIterGVN::NodeOrigin::Graph : PhaseIterGVN::NodeOrigin::Speculative);
2514 phi = hit; // Use existing phi
2515 }
2516 set_ctrl(phi, prev);
2517 }
2518 // Make 'use' use the Phi instead of the old loop body exit value
2519 assert(use->in(idx) == old, "old is still input of use");
2520 // We notify all uses of old, including use, and the indirect uses,
2521 // that may now be optimized because we have replaced old with phi.
2522 _igvn.add_users_to_worklist(old);
2523 if (idx == 0 && use->depends_only_on_test()) {
2524 // If this node depends_only_on_test, it will be rewired to a control input that is not the
2525 // correct test. As a result, it must be pinned otherwise it can be incorrectly rewired to
2526 // a dominating test equivalent to the new control.
2527 Node* pinned_clone = use->pin_node_under_control();
2528 if (pinned_clone != nullptr) {
2529 pinned_clone->set_req(0, phi);
2530 register_new_node_with_ctrl_of(pinned_clone, use);
2531 _igvn.replace_node(use, pinned_clone);
2532 continue;
2533 }
2534 }
2535 _igvn.replace_input_of(use, idx, phi);
2536 if( use->_idx >= new_counter ) { // If updating new phis
2537 // Not needed for correctness, but prevents a weak assert
2538 // in AddPNode from tripping (when we end up with different
2539 // base & derived Phis that will become the same after
2540 // IGVN does CSE).
2541 Node *hit = _igvn.hash_find_insert(use);
2542 if( hit ) // Go ahead and re-hash for hits.
2543 _igvn.replace_node( use, hit );
2544 }
2545 }
2546 }
2547 }
2548
2549 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2550 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2551 bool check_old_new) {
2552 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2553 Node* u = n->fast_out(j);
2554 assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2555 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2556 assert(!phase->ctrl_is_member(loop, u) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2557 if (!phase->ctrl_is_member(loop, u)) {
2558 if (phase->ctrl_is_member(outer_loop, u)) {
2559 wq.push(u);
2560 } else {
2561 // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2562 // the outer loop too
2563 Node* u_c = u->in(0);
2564 if (u_c != nullptr) {
2565 IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2566 if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2567 wq.push(u);
2568 }
2569 }
2570 }
2571 }
2572 }
2573 }
2574 }
2575
2576 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2577 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2578 Node_List& extra_data_nodes) {
2579 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2580 CountedLoopNode* cl = head->as_CountedLoop();
2581 Node* l = cl->outer_loop();
2582 Node* tail = cl->outer_loop_tail();
2583 IfNode* le = cl->outer_loop_end();
2584 Node* sfpt = cl->outer_safepoint();
2585 CountedLoopEndNode* cle = cl->loopexit();
2586 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2587 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2588 IfFalseNode* cle_out = cle->false_proj();
2589
2590 Node* new_sfpt = nullptr;
2591 Node* new_cle_out = cle_out->clone();
2592 old_new.map(cle_out->_idx, new_cle_out);
2593 if (mode == CloneIncludesStripMined) {
2594 // clone outer loop body
2595 Node* new_l = l->clone();
2596 Node* new_tail = tail->clone();
2597 IfNode* new_le = le->clone()->as_If();
2598 new_sfpt = sfpt->clone();
2599
2600 set_loop(new_l, outer_loop->_parent);
2601 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2602 set_loop(new_cle_out, outer_loop->_parent);
2603 set_idom(new_cle_out, new_cle, dd);
2604 set_loop(new_sfpt, outer_loop->_parent);
2605 set_idom(new_sfpt, new_cle_out, dd);
2606 set_loop(new_le, outer_loop->_parent);
2607 set_idom(new_le, new_sfpt, dd);
2608 set_loop(new_tail, outer_loop->_parent);
2609 set_idom(new_tail, new_le, dd);
2610 set_idom(new_cl, new_l, dd);
2611
2612 old_new.map(l->_idx, new_l);
2613 old_new.map(tail->_idx, new_tail);
2614 old_new.map(le->_idx, new_le);
2615 old_new.map(sfpt->_idx, new_sfpt);
2616
2617 new_l->set_req(LoopNode::LoopBackControl, new_tail);
2618 new_l->set_req(0, new_l);
2619 new_tail->set_req(0, new_le);
2620 new_le->set_req(0, new_sfpt);
2621 new_sfpt->set_req(0, new_cle_out);
2622 new_cle_out->set_req(0, new_cle);
2623 new_cl->set_req(LoopNode::EntryControl, new_l);
2624
2625 _igvn.register_new_node_with_optimizer(new_l);
2626 _igvn.register_new_node_with_optimizer(new_tail);
2627 _igvn.register_new_node_with_optimizer(new_le);
2628 } else {
2629 Node *newhead = old_new[loop->_head->_idx];
2630 newhead->as_Loop()->clear_strip_mined();
2631 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2632 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2633 }
2634 // Look at data node that were assigned a control in the outer
2635 // loop: they are kept in the outer loop by the safepoint so start
2636 // from the safepoint node's inputs.
2637 IdealLoopTree* outer_loop = get_loop(l);
2638 Node_Stack stack(2);
2639 stack.push(sfpt, 1);
2640 uint new_counter = C->unique();
2641 while (stack.size() > 0) {
2642 Node* n = stack.node();
2643 uint i = stack.index();
2644 while (i < n->req() &&
2645 (n->in(i) == nullptr ||
2646 !has_ctrl(n->in(i)) ||
2647 get_loop(get_ctrl(n->in(i))) != outer_loop ||
2648 (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2649 i++;
2650 }
2651 if (i < n->req()) {
2652 stack.set_index(i+1);
2653 stack.push(n->in(i), 0);
2654 } else {
2655 assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2656 Node* m = n == sfpt ? new_sfpt : n->clone();
2657 if (m != nullptr) {
2658 for (uint i = 0; i < n->req(); i++) {
2659 if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2660 m->set_req(i, old_new[m->in(i)->_idx]);
2661 }
2662 }
2663 } else {
2664 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2665 }
2666 if (n != sfpt) {
2667 extra_data_nodes.push(n);
2668 _igvn.register_new_node_with_optimizer(m);
2669 assert(get_ctrl(n) == cle_out, "what other control?");
2670 set_ctrl(m, new_cle_out);
2671 old_new.map(n->_idx, m);
2672 }
2673 stack.pop();
2674 }
2675 }
2676 if (mode == CloneIncludesStripMined) {
2677 _igvn.register_new_node_with_optimizer(new_sfpt);
2678 _igvn.register_new_node_with_optimizer(new_cle_out);
2679 }
2680 // Some other transformation may have pessimistically assigned some
2681 // data nodes to the outer loop. Set their control so they are out
2682 // of the outer loop.
2683 ResourceMark rm;
2684 Unique_Node_List wq;
2685 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2686 Node* old = extra_data_nodes.at(i);
2687 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2688 }
2689
2690 for (uint i = 0; i < loop->_body.size(); i++) {
2691 Node* old = loop->_body.at(i);
2692 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2693 }
2694
2695 Node* inner_out = sfpt->in(0);
2696 if (inner_out->outcnt() > 1) {
2697 collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2698 }
2699
2700 Node* new_ctrl = cl->outer_loop_exit();
2701 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2702 for (uint i = 0; i < wq.size(); i++) {
2703 Node* n = wq.at(i);
2704 set_ctrl(n, new_ctrl);
2705 if (n->in(0) != nullptr) {
2706 _igvn.replace_input_of(n, 0, new_ctrl);
2707 }
2708 collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2709 }
2710 } else {
2711 Node *newhead = old_new[loop->_head->_idx];
2712 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2713 }
2714 }
2715
2716 //------------------------------clone_loop-------------------------------------
2717 //
2718 // C L O N E A L O O P B O D Y
2719 //
2720 // This is the basic building block of the loop optimizations. It clones an
2721 // entire loop body. It makes an old_new loop body mapping; with this mapping
2722 // you can find the new-loop equivalent to an old-loop node. All new-loop
2723 // nodes are exactly equal to their old-loop counterparts, all edges are the
2724 // same. All exits from the old-loop now have a RegionNode that merges the
2725 // equivalent new-loop path. This is true even for the normal "loop-exit"
2726 // condition. All uses of loop-invariant old-loop values now come from (one
2727 // or more) Phis that merge their new-loop equivalents.
2728 //
2729 // This operation leaves the graph in an illegal state: there are two valid
2730 // control edges coming from the loop pre-header to both loop bodies. I'll
2731 // definitely have to hack the graph after running this transform.
2732 //
2733 // From this building block I will further edit edges to perform loop peeling
2734 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2735 //
2736 // Parameter side_by_size_idom:
2737 // When side_by_size_idom is null, the dominator tree is constructed for
2738 // the clone loop to dominate the original. Used in construction of
2739 // pre-main-post loop sequence.
2740 // When nonnull, the clone and original are side-by-side, both are
2741 // dominated by the side_by_side_idom node. Used in construction of
2742 // unswitched loops.
2743 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2744 CloneLoopMode mode, Node* side_by_side_idom) {
2745
2746 LoopNode* head = loop->_head->as_Loop();
2747 head->verify_strip_mined(1);
2748
2749 if (C->do_vector_loop() && PrintOpto) {
2750 const char* mname = C->method()->name()->as_quoted_ascii();
2751 if (mname != nullptr) {
2752 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2753 }
2754 }
2755
2756 CloneMap& cm = C->clone_map();
2757 if (C->do_vector_loop()) {
2758 cm.set_clone_idx(cm.max_gen()+1);
2759 #ifndef PRODUCT
2760 if (PrintOpto) {
2761 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2762 loop->dump_head();
2763 }
2764 #endif
2765 }
2766
2767 // Step 1: Clone the loop body. Make the old->new mapping.
2768 clone_loop_body(loop->_body, old_new, &cm);
2769
2770 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2771
2772 // Step 2: Fix the edges in the new body. If the old input is outside the
2773 // loop use it. If the old input is INside the loop, use the corresponding
2774 // new node instead.
2775 fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2776
2777 Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2778 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2779
2780 // Step 3: Now fix control uses. Loop varying control uses have already
2781 // been fixed up (as part of all input edges in Step 2). Loop invariant
2782 // control uses must be either an IfFalse or an IfTrue. Make a merge
2783 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2784 // refer to this.
2785 Node_List worklist;
2786 uint new_counter = C->unique();
2787 fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2788
2789 // Step 4: If loop-invariant use is not control, it must be dominated by a
2790 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2791 // there if needed. Make a Phi there merging old and new used values.
2792 Node_List *split_if_set = nullptr;
2793 Node_List *split_bool_set = nullptr;
2794 Node_List *split_cex_set = nullptr;
2795 fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2796
2797 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2798 Node* old = extra_data_nodes.at(i);
2799 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2800 split_bool_set, split_cex_set, worklist, new_counter,
2801 mode);
2802 }
2803
2804 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2805 // the loop uses a condition set in the loop. The original IF probably
2806 // takes control from one or more OLD Regions (which in turn get from NEW
2807 // Regions). In any case, there will be a set of Phis for each merge point
2808 // from the IF up to where the original BOOL def exists the loop.
2809 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2810
2811 }
2812
2813 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2814 if (split_if_set) {
2815 while (split_if_set->size()) {
2816 Node *iff = split_if_set->pop();
2817 uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2818 if (iff->in(input)->is_Phi()) {
2819 Node *b = clone_iff(iff->in(input)->as_Phi());
2820 _igvn.replace_input_of(iff, input, b);
2821 }
2822 }
2823 }
2824 if (split_bool_set) {
2825 while (split_bool_set->size()) {
2826 Node *b = split_bool_set->pop();
2827 Node *phi = b->in(1);
2828 assert(phi->is_Phi(), "");
2829 CmpNode *cmp = clone_bool((PhiNode*) phi);
2830 _igvn.replace_input_of(b, 1, cmp);
2831 }
2832 }
2833 if (split_cex_set) {
2834 while (split_cex_set->size()) {
2835 Node *b = split_cex_set->pop();
2836 assert(b->in(0)->is_Region(), "");
2837 assert(b->in(1)->is_Phi(), "");
2838 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2839 split_up(b, b->in(0), nullptr);
2840 }
2841 }
2842 }
2843
2844 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2845 uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2846 Node_List*& split_bool_set, Node_List*& split_cex_set) {
2847 for(uint i = 0; i < body.size(); i++ ) {
2848 Node* old = body.at(i);
2849 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2850 split_bool_set, split_cex_set, worklist, new_counter,
2851 mode);
2852 }
2853 }
2854
2855 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2856 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2857 LoopNode* head = loop->_head->as_Loop();
2858 for(uint i = 0; i < body.size(); i++ ) {
2859 Node* old = body.at(i);
2860 if( !old->is_CFG() ) continue;
2861
2862 // Copy uses to a worklist, so I can munge the def-use info
2863 // with impunity.
2864 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2865 worklist.push(old->fast_out(j));
2866 }
2867
2868 while (worklist.size()) { // Visit all uses
2869 Node *use = worklist.pop();
2870 if (!has_node(use)) continue; // Ignore dead nodes
2871 IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2872 if (!loop->is_member(use_loop) && use->is_CFG()) {
2873 // Both OLD and USE are CFG nodes here.
2874 assert(use->is_Proj(), "" );
2875 Node* nnn = old_new[old->_idx];
2876
2877 Node* newuse = nullptr;
2878 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2879 CountedLoopNode* cl = head->as_CountedLoop();
2880 CountedLoopEndNode* cle = cl->loopexit();
2881 // is use the projection that exits the loop from the CountedLoopEndNode?
2882 if (use->in(0) == cle) {
2883 IfFalseNode* cle_out = use->as_IfFalse();
2884 IfNode* le = cl->outer_loop_end();
2885 use = le->false_proj();
2886 use_loop = get_loop(use);
2887 if (mode == CloneIncludesStripMined) {
2888 nnn = old_new[le->_idx];
2889 } else {
2890 newuse = old_new[cle_out->_idx];
2891 }
2892 }
2893 }
2894 if (newuse == nullptr) {
2895 newuse = use->clone();
2896 }
2897
2898 // Clone the loop exit control projection
2899 if (C->do_vector_loop() && cm != nullptr) {
2900 cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2901 }
2902 newuse->set_req(0,nnn);
2903 _igvn.register_new_node_with_optimizer(newuse);
2904 set_loop(newuse, use_loop);
2905 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2906
2907 // We need a Region to merge the exit from the peeled body and the
2908 // exit from the old loop body.
2909 RegionNode *r = new RegionNode(3);
2910 uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2911 assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2912
2913 // The original user of 'use' uses 'r' instead.
2914 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2915 Node* useuse = use->last_out(l);
2916 _igvn.rehash_node_delayed(useuse);
2917 uint uses_found = 0;
2918 if (useuse->in(0) == use) {
2919 useuse->set_req(0, r);
2920 uses_found++;
2921 if (useuse->is_CFG()) {
2922 // This is not a dom_depth > dd_r because when new
2923 // control flow is constructed by a loop opt, a node and
2924 // its dominator can end up at the same dom_depth
2925 assert(dom_depth(useuse) >= dd_r, "");
2926 set_idom(useuse, r, dom_depth(useuse));
2927 }
2928 }
2929 for (uint k = 1; k < useuse->req(); k++) {
2930 if( useuse->in(k) == use ) {
2931 useuse->set_req(k, r);
2932 uses_found++;
2933 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2934 // This is not a dom_depth > dd_r because when new
2935 // control flow is constructed by a loop opt, a node
2936 // and its dominator can end up at the same dom_depth
2937 assert(dom_depth(useuse) >= dd_r , "");
2938 set_idom(useuse, r, dom_depth(useuse));
2939 }
2940 }
2941 }
2942 l -= uses_found; // we deleted 1 or more copies of this edge
2943 }
2944
2945 assert(use->is_Proj(), "loop exit should be projection");
2946 // replace_node_and_forward_ctrl() below moves all nodes that are:
2947 // - control dependent on the loop exit or
2948 // - have control set to the loop exit
2949 // below the post-loop merge point.
2950 // replace_node_and_forward_ctrl() takes a dead control as first input.
2951 // To make it possible to use it, the loop exit projection is cloned and becomes the
2952 // new exit projection. The initial one becomes dead and is "replaced" by the region.
2953 Node* use_clone = use->clone();
2954 register_control(use_clone, use_loop, idom(use), dom_depth(use));
2955 // Now finish up 'r'
2956 r->set_req(1, newuse);
2957 r->set_req(2, use_clone);
2958 _igvn.register_new_node_with_optimizer(r);
2959 set_loop(r, use_loop);
2960 set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2961 replace_node_and_forward_ctrl(use, r);
2962 // Map the (cloned) old use to the new merge point
2963 old_new.map(use_clone->_idx, r);
2964 } // End of if a loop-exit test
2965 }
2966 }
2967 }
2968
2969 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2970 IdealLoopTree* parent, bool partial) {
2971 for(uint i = 0; i < body.size(); i++ ) {
2972 Node *old = body.at(i);
2973 Node *nnn = old_new[old->_idx];
2974 // Fix CFG/Loop controlling the new node
2975 if (has_ctrl(old)) {
2976 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2977 } else {
2978 set_loop(nnn, parent);
2979 if (old->outcnt() > 0) {
2980 Node* dom = idom(old);
2981 if (old_new[dom->_idx] != nullptr) {
2982 dom = old_new[dom->_idx];
2983 set_idom(nnn, dom, dd );
2984 }
2985 }
2986 }
2987 // Correct edges to the new node
2988 for (uint j = 0; j < nnn->req(); j++) {
2989 Node *n = nnn->in(j);
2990 if (n != nullptr) {
2991 IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2992 if (loop->is_member(old_in_loop)) {
2993 if (old_new[n->_idx] != nullptr) {
2994 nnn->set_req(j, old_new[n->_idx]);
2995 } else {
2996 assert(!body.contains(n), "");
2997 assert(partial, "node not cloned");
2998 }
2999 }
3000 }
3001 }
3002 _igvn.hash_find_insert(nnn);
3003 }
3004 }
3005
3006 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
3007 for (uint i = 0; i < body.size(); i++) {
3008 Node* old = body.at(i);
3009 Node* nnn = old->clone();
3010 old_new.map(old->_idx, nnn);
3011 if (C->do_vector_loop() && cm != nullptr) {
3012 cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
3013 }
3014 _igvn.register_new_node_with_optimizer(nnn);
3015 }
3016 }
3017
3018
3019 //---------------------- stride_of_possible_iv -------------------------------------
3020 // Looks for an iff/bool/comp with one operand of the compare
3021 // being a cycle involving an add and a phi,
3022 // with an optional truncation (left-shift followed by a right-shift)
3023 // of the add. Returns zero if not an iv.
3024 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
3025 const TypeInteger* ttype = nullptr;
3026 if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
3027 return 0;
3028 }
3029 BoolNode* bl = iff->in(1)->as_Bool();
3030 Node* cmp = bl->in(1);
3031 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
3032 return 0;
3033 }
3034 // Must have an invariant operand
3035 if (ctrl_is_member(get_loop(iff), cmp->in(2))) {
3036 return 0;
3037 }
3038 Node* add2 = nullptr;
3039 Node* cmp1 = cmp->in(1);
3040 if (cmp1->is_Phi()) {
3041 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
3042 Node* phi = cmp1;
3043 for (uint i = 1; i < phi->req(); i++) {
3044 Node* in = phi->in(i);
3045 CountedLoopConverter::TruncatedIncrement add(T_INT);
3046 add.build(in);
3047 if (add.is_valid() && add.incr()->in(1) == phi) {
3048 add2 = add.incr()->in(2);
3049 break;
3050 }
3051 }
3052 } else {
3053 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
3054 Node* addtrunc = cmp1;
3055 CountedLoopConverter::TruncatedIncrement add(T_INT);
3056 add.build(addtrunc);
3057 if (add.is_valid() && add.incr()->in(1)->is_Phi()) {
3058 Node* phi = add.incr()->in(1);
3059 for (uint i = 1; i < phi->req(); i++) {
3060 if (phi->in(i) == addtrunc) {
3061 add2 = add.incr()->in(2);
3062 break;
3063 }
3064 }
3065 }
3066 }
3067 if (add2 != nullptr) {
3068 const TypeInt* add2t = _igvn.type(add2)->is_int();
3069 if (add2t->is_con()) {
3070 return add2t->get_con();
3071 }
3072 }
3073 return 0;
3074 }
3075
3076
3077 //---------------------- stay_in_loop -------------------------------------
3078 // Return the (unique) control output node that's in the loop (if it exists.)
3079 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
3080 Node* unique = nullptr;
3081 if (!n) return nullptr;
3082 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3083 Node* use = n->fast_out(i);
3084 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
3085 if (unique != nullptr) {
3086 return nullptr;
3087 }
3088 unique = use;
3089 }
3090 }
3091 return unique;
3092 }
3093
3094 //------------------------------ register_node -------------------------------------
3095 // Utility to register node "n" with PhaseIdealLoop
3096 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
3097 _igvn.register_new_node_with_optimizer(n);
3098 loop->_body.push(n);
3099 if (n->is_CFG()) {
3100 set_loop(n, loop);
3101 set_idom(n, pred, ddepth);
3102 } else {
3103 set_ctrl(n, pred);
3104 }
3105 }
3106
3107 //------------------------------ proj_clone -------------------------------------
3108 // Utility to create an if-projection
3109 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
3110 ProjNode* c = p->clone()->as_Proj();
3111 c->set_req(0, iff);
3112 return c;
3113 }
3114
3115 //------------------------------ short_circuit_if -------------------------------------
3116 // Force the iff control output to be the live_proj
3117 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
3118 guarantee(live_proj != nullptr, "null projection");
3119 int proj_con = live_proj->_con;
3120 assert(proj_con == 0 || proj_con == 1, "false or true projection");
3121 Node* con = intcon(proj_con);
3122 if (iff) {
3123 iff->set_req(1, con);
3124 }
3125 return con;
3126 }
3127
3128 //------------------------------ insert_if_before_proj -------------------------------------
3129 // Insert a new if before an if projection (* - new node)
3130 //
3131 // before
3132 // if(test)
3133 // / \
3134 // v v
3135 // other-proj proj (arg)
3136 //
3137 // after
3138 // if(test)
3139 // / \
3140 // / v
3141 // | * proj-clone
3142 // v |
3143 // other-proj v
3144 // * new_if(relop(cmp[IU](left,right)))
3145 // / \
3146 // v v
3147 // * new-proj proj
3148 // (returned)
3149 //
3150 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
3151 IfNode* iff = proj->in(0)->as_If();
3152 IdealLoopTree *loop = get_loop(proj);
3153 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3154 uint ddepth = dom_depth(proj);
3155
3156 _igvn.rehash_node_delayed(iff);
3157 _igvn.rehash_node_delayed(proj);
3158
3159 proj->set_req(0, nullptr); // temporary disconnect
3160 ProjNode* proj2 = proj_clone(proj, iff);
3161 register_node(proj2, loop, iff, ddepth);
3162
3163 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
3164 register_node(cmp, loop, proj2, ddepth);
3165
3166 BoolNode* bol = new BoolNode(cmp, relop);
3167 register_node(bol, loop, proj2, ddepth);
3168
3169 int opcode = iff->Opcode();
3170 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
3171 IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
3172 register_node(new_if, loop, proj2, ddepth);
3173
3174 proj->set_req(0, new_if); // reattach
3175 set_idom(proj, new_if, ddepth);
3176
3177 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
3178 guarantee(new_exit != nullptr, "null exit node");
3179 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
3180
3181 return new_exit;
3182 }
3183
3184 //------------------------------ insert_region_before_proj -------------------------------------
3185 // Insert a region before an if projection (* - new node)
3186 //
3187 // before
3188 // if(test)
3189 // / |
3190 // v |
3191 // proj v
3192 // other-proj
3193 //
3194 // after
3195 // if(test)
3196 // / |
3197 // v |
3198 // * proj-clone v
3199 // | other-proj
3200 // v
3201 // * new-region
3202 // |
3203 // v
3204 // * dum_if
3205 // / \
3206 // v \
3207 // * dum-proj v
3208 // proj
3209 //
3210 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3211 IfNode* iff = proj->in(0)->as_If();
3212 IdealLoopTree *loop = get_loop(proj);
3213 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3214 uint ddepth = dom_depth(proj);
3215
3216 _igvn.rehash_node_delayed(iff);
3217 _igvn.rehash_node_delayed(proj);
3218
3219 proj->set_req(0, nullptr); // temporary disconnect
3220 ProjNode* proj2 = proj_clone(proj, iff);
3221 register_node(proj2, loop, iff, ddepth);
3222
3223 RegionNode* reg = new RegionNode(2);
3224 reg->set_req(1, proj2);
3225 register_node(reg, loop, iff, ddepth);
3226
3227 IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3228 register_node(dum_if, loop, reg, ddepth);
3229
3230 proj->set_req(0, dum_if); // reattach
3231 set_idom(proj, dum_if, ddepth);
3232
3233 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3234 register_node(dum_proj, loop, dum_if, ddepth);
3235
3236 return reg;
3237 }
3238
3239 // Idea
3240 // ----
3241 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3242 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3243 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3244 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3245 // test alone instead:
3246 //
3247 // Before Partial Peeling:
3248 // Loop:
3249 // <peeled section>
3250 // Split off signed loop exit test
3251 // <-- CUT HERE -->
3252 // Unchanged unsigned loop exit test
3253 // <rest of unpeeled section>
3254 // goto Loop
3255 //
3256 // After Partial Peeling:
3257 // <cloned peeled section>
3258 // Cloned split off signed loop exit test
3259 // Loop:
3260 // Unchanged unsigned loop exit test
3261 // <rest of unpeeled section>
3262 // <peeled section>
3263 // Split off signed loop exit test
3264 // goto Loop
3265 //
3266 // Details
3267 // -------
3268 // Before:
3269 // if (i <u limit) Unsigned loop exit condition
3270 // / |
3271 // v v
3272 // exit-proj stay-in-loop-proj
3273 //
3274 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3275 // before the CmpU on the stay-in-loop path and keep both tests:
3276 //
3277 // if (i <u limit) Signed loop exit test
3278 // / |
3279 // / if (i <u limit) Unsigned loop exit test
3280 // / / |
3281 // v v v
3282 // exit-region stay-in-loop-proj
3283 //
3284 // Implementation
3285 // --------------
3286 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3287 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3288 // exit tests is preserved, and their loop nesting is correct.
3289 //
3290 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3291 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3292 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3293 //
3294 // if (stay-in-loop-const) Killed original unsigned loop exit test
3295 // / |
3296 // / v
3297 // / if (i < limit) Split off signed loop exit test
3298 // / / |
3299 // / / v
3300 // / / if (i <u limit) Cloned unsigned loop exit test
3301 // / / / |
3302 // v v v |
3303 // exit-region |
3304 // | |
3305 // dummy-if |
3306 // / | |
3307 // dead | |
3308 // v v
3309 // exit-proj stay-in-loop-proj
3310 //
3311 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3312 // loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3313 //
3314 // Requirements
3315 // ------------
3316 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3317 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3318 // Otherwise, we need to bail out (see comments in the code below).
3319 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3320 const bool Signed = true;
3321 const bool Unsigned = false;
3322
3323 BoolNode* bol = if_cmpu->in(1)->as_Bool();
3324 if (bol->_test._test != BoolTest::lt) {
3325 return nullptr;
3326 }
3327 CmpNode* cmpu = bol->in(1)->as_Cmp();
3328 assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3329
3330 int stride = stride_of_possible_iv(if_cmpu);
3331 if (stride == 0) {
3332 return nullptr;
3333 }
3334
3335 Node* lp_proj = stay_in_loop(if_cmpu, loop);
3336 guarantee(lp_proj != nullptr, "null loop node");
3337
3338 ProjNode* lp_continue = lp_proj->as_Proj();
3339 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3340 if (!lp_exit->is_IfFalse()) {
3341 // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3342 // We therefore can't add a single exit condition.
3343 return nullptr;
3344 }
3345 // The unsigned loop exit condition is
3346 // !(i <u limit)
3347 // = i >=u limit
3348 //
3349 // First, we note that for any x for which
3350 // 0 <= x <= INT_MAX
3351 // we can convert x to an unsigned int and still get the same guarantee:
3352 // 0 <= (uint) x <= INT_MAX = (uint) INT_MAX
3353 // 0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX (LEMMA)
3354 //
3355 // With that in mind, if
3356 // limit >= 0 (COND)
3357 // then the unsigned loop exit condition
3358 // i >=u limit (ULE)
3359 // is equivalent to
3360 // i < 0 || i >= limit (SLE-full)
3361 // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3362 // (uint) i >=u MAX_INT >= limit >= 0
3363 // or otherwise
3364 // i >= limit >= 0
3365 // holds due to (LEMMA).
3366 //
3367 // For completeness, a counterexample with limit < 0:
3368 // Assume i = -3 and limit = -2:
3369 // i < 0
3370 // -2 < 0
3371 // is true and thus also "i < 0 || i >= limit". But
3372 // i >=u limit
3373 // -3 >=u -2
3374 // is false.
3375 Node* limit = cmpu->in(2);
3376 const TypeInt* type_limit = _igvn.type(limit)->is_int();
3377 if (type_limit->_lo < 0) {
3378 return nullptr;
3379 }
3380
3381 // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3382 // stride < 0:
3383 // i < 0 (SLE = SLE-negative)
3384 // stride > 0:
3385 // i >= limit (SLE = SLE-positive)
3386 // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3387 //
3388 // Loop:
3389 // <peeled section>
3390 // i >= limit (SLE-positive)
3391 // <-- CUT HERE -->
3392 // i >=u limit (ULE)
3393 // <rest of unpeeled section>
3394 // goto Loop
3395 //
3396 // We exit the loop if:
3397 // (SLE) is true OR (ULE) is true
3398 // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3399 // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3400 // (SLE) IMPLIES (ULE)
3401 // This indeed holds when (COND) is given:
3402 // - stride > 0:
3403 // i >= limit // (SLE = SLE-positive)
3404 // i >= limit >= 0 // (COND)
3405 // i >=u limit >= 0 // (LEMMA)
3406 // which is the unsigned loop exit condition (ULE).
3407 // - stride < 0:
3408 // i < 0 // (SLE = SLE-negative)
3409 // (uint) i >u MAX_INT // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3410 // MAX_INT >= limit >= 0 // (COND)
3411 // MAX_INT >=u limit >= 0 // (LEMMA)
3412 // and thus from (NEG) and (LEMMA):
3413 // i >=u limit
3414 // which is the unsigned loop exit condition (ULE).
3415 //
3416 //
3417 // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3418 // <cloned peeled section>
3419 // i >= limit (SLE-positive)
3420 // Loop:
3421 // i >=u limit (ULE)
3422 // <rest of unpeeled section>
3423 // <peeled section>
3424 // i >= limit (SLE-positive)
3425 // goto Loop
3426 Node* rhs_cmpi;
3427 if (stride > 0) {
3428 rhs_cmpi = limit; // For i >= limit
3429 } else {
3430 rhs_cmpi = makecon(TypeInt::ZERO); // For i < 0
3431 }
3432 // Create a new region on the exit path
3433 RegionNode* reg = insert_region_before_proj(lp_exit);
3434 guarantee(reg != nullptr, "null region node");
3435
3436 // Clone the if-cmpu-true-false using a signed compare
3437 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3438 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3439 reg->add_req(cmpi_exit);
3440
3441 // Clone the if-cmpu-true-false
3442 BoolTest::mask rel_u = bol->_test._test;
3443 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3444 reg->add_req(cmpu_exit);
3445
3446 // Force original if to stay in loop.
3447 short_circuit_if(if_cmpu, lp_continue);
3448
3449 return cmpi_exit->in(0)->as_If();
3450 }
3451
3452 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3453 // Remove a previously inserted signed compare loop exit.
3454 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3455 Node* lp_proj = stay_in_loop(if_cmp, loop);
3456 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3457 stay_in_loop(lp_proj, loop)->is_If() &&
3458 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3459 Node* con = makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3460 if_cmp->set_req(1, con);
3461 }
3462
3463 //------------------------------ scheduled_nodelist -------------------------------------
3464 // Create a post order schedule of nodes that are in the
3465 // "member" set. The list is returned in "sched".
3466 // The first node in "sched" is the loop head, followed by
3467 // nodes which have no inputs in the "member" set, and then
3468 // followed by the nodes that have an immediate input dependence
3469 // on a node in "sched".
3470 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3471
3472 assert(member.test(loop->_head->_idx), "loop head must be in member set");
3473 VectorSet visited;
3474 Node_Stack nstack(loop->_body.size());
3475
3476 Node* n = loop->_head; // top of stack is cached in "n"
3477 uint idx = 0;
3478 visited.set(n->_idx);
3479
3480 // Initially push all with no inputs from within member set
3481 for(uint i = 0; i < loop->_body.size(); i++ ) {
3482 Node *elt = loop->_body.at(i);
3483 if (member.test(elt->_idx)) {
3484 bool found = false;
3485 for (uint j = 0; j < elt->req(); j++) {
3486 Node* def = elt->in(j);
3487 if (def && member.test(def->_idx) && def != elt) {
3488 found = true;
3489 break;
3490 }
3491 }
3492 if (!found && elt != loop->_head) {
3493 nstack.push(n, idx);
3494 n = elt;
3495 assert(!visited.test(n->_idx), "not seen yet");
3496 visited.set(n->_idx);
3497 }
3498 }
3499 }
3500
3501 // traverse out's that are in the member set
3502 while (true) {
3503 if (idx < n->outcnt()) {
3504 Node* use = n->raw_out(idx);
3505 idx++;
3506 if (!visited.test_set(use->_idx)) {
3507 if (member.test(use->_idx)) {
3508 nstack.push(n, idx);
3509 n = use;
3510 idx = 0;
3511 }
3512 }
3513 } else {
3514 // All outputs processed
3515 sched.push(n);
3516 if (nstack.is_empty()) break;
3517 n = nstack.node();
3518 idx = nstack.index();
3519 nstack.pop();
3520 }
3521 }
3522 }
3523
3524
3525 //------------------------------ has_use_in_set -------------------------------------
3526 // Has a use in the vector set
3527 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3528 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3529 Node* use = n->fast_out(j);
3530 if (vset.test(use->_idx)) {
3531 return true;
3532 }
3533 }
3534 return false;
3535 }
3536
3537
3538 //------------------------------ has_use_internal_to_set -------------------------------------
3539 // Has use internal to the vector set (ie. not in a phi at the loop head)
3540 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3541 Node* head = loop->_head;
3542 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3543 Node* use = n->fast_out(j);
3544 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3545 return true;
3546 }
3547 }
3548 return false;
3549 }
3550
3551
3552 //------------------------------ clone_for_use_outside_loop -------------------------------------
3553 // clone "n" for uses that are outside of loop
3554 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3555 int cloned = 0;
3556 assert(worklist.size() == 0, "should be empty");
3557 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3558 Node* use = n->fast_out(j);
3559 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3560 worklist.push(use);
3561 }
3562 }
3563
3564 if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3565 "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3566 return -1;
3567 }
3568
3569 while( worklist.size() ) {
3570 Node *use = worklist.pop();
3571 if (!has_node(use) || use->in(0) == C->top()) continue;
3572 uint j;
3573 for (j = 0; j < use->req(); j++) {
3574 if (use->in(j) == n) break;
3575 }
3576 assert(j < use->req(), "must be there");
3577
3578 // clone "n" and insert it between the inputs of "n" and the use outside the loop
3579 Node* n_clone = n->clone();
3580 _igvn.replace_input_of(use, j, n_clone);
3581 cloned++;
3582 Node* use_c;
3583 if (!use->is_Phi()) {
3584 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3585 } else {
3586 // Use in a phi is considered a use in the associated predecessor block
3587 use_c = use->in(0)->in(j);
3588 }
3589 set_ctrl(n_clone, use_c);
3590 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3591 get_loop(use_c)->_body.push(n_clone);
3592 _igvn.register_new_node_with_optimizer(n_clone);
3593 #ifndef PRODUCT
3594 if (TracePartialPeeling) {
3595 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3596 }
3597 #endif
3598 }
3599 return cloned;
3600 }
3601
3602
3603 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3604 // clone "n" for special uses that are in the not_peeled region.
3605 // If these def-uses occur in separate blocks, the code generator
3606 // marks the method as not compilable. For example, if a "BoolNode"
3607 // is in a different basic block than the "IfNode" that uses it, then
3608 // the compilation is aborted in the code generator.
3609 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3610 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3611 if (n->is_Phi() || n->is_Load()) {
3612 return;
3613 }
3614 assert(worklist.size() == 0, "should be empty");
3615 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3616 Node* use = n->fast_out(j);
3617 if ( not_peel.test(use->_idx) &&
3618 (use->is_If() || use->is_CMove() || use->is_Bool() || use->is_OpaqueInitializedAssertionPredicate()) &&
3619 use->in(1) == n) {
3620 worklist.push(use);
3621 }
3622 }
3623 if (worklist.size() > 0) {
3624 // clone "n" and insert it between inputs of "n" and the use
3625 Node* n_clone = n->clone();
3626 loop->_body.push(n_clone);
3627 _igvn.register_new_node_with_optimizer(n_clone);
3628 set_ctrl(n_clone, get_ctrl(n));
3629 sink_list.push(n_clone);
3630 not_peel.set(n_clone->_idx);
3631 #ifndef PRODUCT
3632 if (TracePartialPeeling) {
3633 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3634 }
3635 #endif
3636 while( worklist.size() ) {
3637 Node *use = worklist.pop();
3638 _igvn.rehash_node_delayed(use);
3639 for (uint j = 1; j < use->req(); j++) {
3640 if (use->in(j) == n) {
3641 use->set_req(j, n_clone);
3642 }
3643 }
3644 }
3645 }
3646 }
3647
3648
3649 //------------------------------ insert_phi_for_loop -------------------------------------
3650 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3651 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3652 Node *phi = PhiNode::make(lp, back_edge_val);
3653 phi->set_req(LoopNode::EntryControl, lp_entry_val);
3654 // Use existing phi if it already exists
3655 Node *hit = _igvn.hash_find_insert(phi);
3656 if( hit == nullptr ) {
3657 _igvn.register_new_node_with_optimizer(phi);
3658 set_ctrl(phi, lp);
3659 } else {
3660 // Remove the new phi from the graph and use the hit
3661 _igvn.remove_dead_node(phi, PhaseIterGVN::NodeOrigin::Speculative);
3662 phi = hit;
3663 }
3664 _igvn.replace_input_of(use, idx, phi);
3665 }
3666
3667 #ifdef ASSERT
3668 //------------------------------ is_valid_loop_partition -------------------------------------
3669 // Validate the loop partition sets: peel and not_peel
3670 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3671 VectorSet& not_peel ) {
3672 uint i;
3673 // Check that peel_list entries are in the peel set
3674 for (i = 0; i < peel_list.size(); i++) {
3675 if (!peel.test(peel_list.at(i)->_idx)) {
3676 return false;
3677 }
3678 }
3679 // Check at loop members are in one of peel set or not_peel set
3680 for (i = 0; i < loop->_body.size(); i++ ) {
3681 Node *def = loop->_body.at(i);
3682 uint di = def->_idx;
3683 // Check that peel set elements are in peel_list
3684 if (peel.test(di)) {
3685 if (not_peel.test(di)) {
3686 return false;
3687 }
3688 // Must be in peel_list also
3689 bool found = false;
3690 for (uint j = 0; j < peel_list.size(); j++) {
3691 if (peel_list.at(j)->_idx == di) {
3692 found = true;
3693 break;
3694 }
3695 }
3696 if (!found) {
3697 return false;
3698 }
3699 } else if (not_peel.test(di)) {
3700 if (peel.test(di)) {
3701 return false;
3702 }
3703 } else {
3704 return false;
3705 }
3706 }
3707 return true;
3708 }
3709
3710 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3711 // Ensure a use outside of loop is of the right form
3712 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3713 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3714 return (use->is_Phi() &&
3715 use_c->is_Region() && use_c->req() == 3 &&
3716 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3717 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3718 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3719 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3720 }
3721
3722 //------------------------------ is_valid_clone_loop_form -------------------------------------
3723 // Ensure that all uses outside of loop are of the right form
3724 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3725 uint orig_exit_idx, uint clone_exit_idx) {
3726 uint len = peel_list.size();
3727 for (uint i = 0; i < len; i++) {
3728 Node *def = peel_list.at(i);
3729
3730 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3731 Node *use = def->fast_out(j);
3732 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3733 if (!loop->is_member(get_loop(use_c))) {
3734 // use is not in the loop, check for correct structure
3735 if (use->in(0) == def) {
3736 // Okay
3737 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3738 return false;
3739 }
3740 }
3741 }
3742 }
3743 return true;
3744 }
3745 #endif
3746
3747 //------------------------------ partial_peel -------------------------------------
3748 // Partially peel (aka loop rotation) the top portion of a loop (called
3749 // the peel section below) by cloning it and placing one copy just before
3750 // the new loop head and the other copy at the bottom of the new loop.
3751 //
3752 // before after where it came from
3753 //
3754 // stmt1 stmt1
3755 // loop: stmt2 clone
3756 // stmt2 if condA goto exitA clone
3757 // if condA goto exitA new_loop: new
3758 // stmt3 stmt3 clone
3759 // if !condB goto loop if condB goto exitB clone
3760 // exitB: stmt2 orig
3761 // stmt4 if !condA goto new_loop orig
3762 // exitA: goto exitA
3763 // exitB:
3764 // stmt4
3765 // exitA:
3766 //
3767 // Step 1: find the cut point: an exit test on probable
3768 // induction variable.
3769 // Step 2: schedule (with cloning) operations in the peel
3770 // section that can be executed after the cut into
3771 // the section that is not peeled. This may need
3772 // to clone operations into exit blocks. For
3773 // instance, a reference to A[i] in the not-peel
3774 // section and a reference to B[i] in an exit block
3775 // may cause a left-shift of i by 2 to be placed
3776 // in the peel block. This step will clone the left
3777 // shift into the exit block and sink the left shift
3778 // from the peel to the not-peel section.
3779 // Step 3: clone the loop, retarget the control, and insert
3780 // phis for values that are live across the new loop
3781 // head. This is very dependent on the graph structure
3782 // from clone_loop. It creates region nodes for
3783 // exit control and associated phi nodes for values
3784 // flow out of the loop through that exit. The region
3785 // node is dominated by the clone's control projection.
3786 // So the clone's peel section is placed before the
3787 // new loop head, and the clone's not-peel section is
3788 // forms the top part of the new loop. The original
3789 // peel section forms the tail of the new loop.
3790 // Step 4: update the dominator tree and recompute the
3791 // dominator depth.
3792 //
3793 // orig
3794 //
3795 // stmt1
3796 // |
3797 // v
3798 // predicates
3799 // |
3800 // v
3801 // loop<----+
3802 // | |
3803 // stmt2 |
3804 // | |
3805 // v |
3806 // ifA |
3807 // / | |
3808 // v v |
3809 // false true ^ <-- last_peel
3810 // / | |
3811 // / ===|==cut |
3812 // / stmt3 | <-- first_not_peel
3813 // / | |
3814 // | v |
3815 // v ifB |
3816 // exitA: / \ |
3817 // / \ |
3818 // v v |
3819 // false true |
3820 // / \ |
3821 // / ----+
3822 // |
3823 // v
3824 // exitB:
3825 // stmt4
3826 //
3827 //
3828 // after clone loop
3829 //
3830 // stmt1
3831 // |
3832 // v
3833 // predicates
3834 // / \
3835 // clone / \ orig
3836 // / \
3837 // / \
3838 // v v
3839 // +---->loop loop<----+
3840 // | | | |
3841 // | stmt2 stmt2 |
3842 // | | | |
3843 // | v v |
3844 // | ifA ifA |
3845 // | | \ / | |
3846 // | v v v v |
3847 // ^ true false false true ^ <-- last_peel
3848 // | | ^ \ / | |
3849 // | cut==|== \ \ / ===|==cut |
3850 // | stmt3 \ \ / stmt3 | <-- first_not_peel
3851 // | | dom | | | |
3852 // | v \ 1v v2 v |
3853 // | ifB regionA ifB |
3854 // | / \ | / \ |
3855 // | / \ v / \ |
3856 // | v v exitA: v v |
3857 // | true false false true |
3858 // | / ^ \ / \ |
3859 // +---- \ \ / ----+
3860 // dom \ /
3861 // \ 1v v2
3862 // regionB
3863 // |
3864 // v
3865 // exitB:
3866 // stmt4
3867 //
3868 //
3869 // after partial peel
3870 //
3871 // stmt1
3872 // |
3873 // v
3874 // predicates
3875 // /
3876 // clone / orig
3877 // / TOP
3878 // / \
3879 // v v
3880 // TOP->loop loop----+
3881 // | | |
3882 // stmt2 stmt2 |
3883 // | | |
3884 // v v |
3885 // ifA ifA |
3886 // | \ / | |
3887 // v v v v |
3888 // true false false true | <-- last_peel
3889 // | ^ \ / +------|---+
3890 // +->newloop \ \ / === ==cut | |
3891 // | stmt3 \ \ / TOP | |
3892 // | | dom | | stmt3 | | <-- first_not_peel
3893 // | v \ 1v v2 v | |
3894 // | ifB regionA ifB ^ v
3895 // | / \ | / \ | |
3896 // | / \ v / \ | |
3897 // | v v exitA: v v | |
3898 // | true false false true | |
3899 // | / ^ \ / \ | |
3900 // | | \ \ / v | |
3901 // | | dom \ / TOP | |
3902 // | | \ 1v v2 | |
3903 // ^ v regionB | |
3904 // | | | | |
3905 // | | v ^ v
3906 // | | exitB: | |
3907 // | | stmt4 | |
3908 // | +------------>-----------------+ |
3909 // | |
3910 // +-----------------<---------------------+
3911 //
3912 //
3913 // final graph
3914 //
3915 // stmt1
3916 // |
3917 // v
3918 // predicates
3919 // |
3920 // v
3921 // stmt2 clone
3922 // |
3923 // v
3924 // ........> ifA clone
3925 // : / |
3926 // dom / |
3927 // : v v
3928 // : false true
3929 // : | |
3930 // : | v
3931 // : | newloop<-----+
3932 // : | | |
3933 // : | stmt3 clone |
3934 // : | | |
3935 // : | v |
3936 // : | ifB |
3937 // : | / \ |
3938 // : | v v |
3939 // : | false true |
3940 // : | | | |
3941 // : | v stmt2 |
3942 // : | exitB: | |
3943 // : | stmt4 v |
3944 // : | ifA orig |
3945 // : | / \ |
3946 // : | / \ |
3947 // : | v v |
3948 // : | false true |
3949 // : | / \ |
3950 // : v v -----+
3951 // RegionA
3952 // |
3953 // v
3954 // exitA
3955 //
3956 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3957
3958 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3959 if (!loop->_head->is_Loop()) {
3960 return false;
3961 }
3962 LoopNode *head = loop->_head->as_Loop();
3963
3964 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3965 return false;
3966 }
3967
3968 // Check for complex exit control
3969 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3970 Node *n = loop->_body.at(ii);
3971 int opc = n->Opcode();
3972 if (n->is_Call() ||
3973 opc == Op_Catch ||
3974 opc == Op_CatchProj ||
3975 opc == Op_Jump ||
3976 opc == Op_JumpProj) {
3977 #ifndef PRODUCT
3978 if (TracePartialPeeling) {
3979 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3980 }
3981 #endif
3982 return false;
3983 }
3984 }
3985
3986 int dd = dom_depth(head);
3987
3988 // Step 1: find cut point
3989
3990 // Walk up dominators to loop head looking for first loop exit
3991 // which is executed on every path thru loop.
3992 IfNode *peel_if = nullptr;
3993 IfNode *peel_if_cmpu = nullptr;
3994
3995 Node *iff = loop->tail();
3996 while (iff != head) {
3997 if (iff->is_If()) {
3998 Node *ctrl = get_ctrl(iff->in(1));
3999 if (ctrl->is_top()) return false; // Dead test on live IF.
4000 // If loop-varying exit-test, check for induction variable
4001 if (loop->is_member(get_loop(ctrl)) &&
4002 loop->is_loop_exit(iff) &&
4003 is_possible_iv_test(iff)) {
4004 Node* cmp = iff->in(1)->in(1);
4005 if (cmp->Opcode() == Op_CmpI) {
4006 peel_if = iff->as_If();
4007 } else {
4008 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
4009 peel_if_cmpu = iff->as_If();
4010 }
4011 }
4012 }
4013 iff = idom(iff);
4014 }
4015
4016 // Prefer signed compare over unsigned compare.
4017 IfNode* new_peel_if = nullptr;
4018 if (peel_if == nullptr) {
4019 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
4020 return false; // No peel point found
4021 }
4022 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
4023 if (new_peel_if == nullptr) {
4024 return false; // No peel point found
4025 }
4026 peel_if = new_peel_if;
4027 }
4028 Node* last_peel = stay_in_loop(peel_if, loop);
4029 Node* first_not_peeled = stay_in_loop(last_peel, loop);
4030 if (first_not_peeled == nullptr || first_not_peeled == head) {
4031 return false;
4032 }
4033
4034 #ifndef PRODUCT
4035 if (TraceLoopOpts) {
4036 tty->print("PartialPeel ");
4037 loop->dump_head();
4038 }
4039
4040 if (TracePartialPeeling) {
4041 tty->print_cr("before partial peel one iteration");
4042 Node_List wl;
4043 Node* t = head->in(2);
4044 while (true) {
4045 wl.push(t);
4046 if (t == head) break;
4047 t = idom(t);
4048 }
4049 while (wl.size() > 0) {
4050 Node* tt = wl.pop();
4051 tt->dump();
4052 if (tt == last_peel) tty->print_cr("-- cut --");
4053 }
4054 }
4055 #endif
4056
4057 C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
4058
4059 VectorSet peel;
4060 VectorSet not_peel;
4061 Node_List peel_list;
4062 Node_List worklist;
4063 Node_List sink_list;
4064
4065 uint estimate = loop->est_loop_clone_sz(1);
4066 if (exceeding_node_budget(estimate)) {
4067 return false;
4068 }
4069
4070 // Set of cfg nodes to peel are those that are executable from
4071 // the head through last_peel.
4072 assert(worklist.size() == 0, "should be empty");
4073 worklist.push(head);
4074 peel.set(head->_idx);
4075 while (worklist.size() > 0) {
4076 Node *n = worklist.pop();
4077 if (n != last_peel) {
4078 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
4079 Node* use = n->fast_out(j);
4080 if (use->is_CFG() &&
4081 loop->is_member(get_loop(use)) &&
4082 !peel.test_set(use->_idx)) {
4083 worklist.push(use);
4084 }
4085 }
4086 }
4087 }
4088
4089 // Set of non-cfg nodes to peel are those that are control
4090 // dependent on the cfg nodes.
4091 for (uint i = 0; i < loop->_body.size(); i++) {
4092 Node *n = loop->_body.at(i);
4093 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
4094 if (peel.test(n_c->_idx)) {
4095 peel.set(n->_idx);
4096 } else {
4097 not_peel.set(n->_idx);
4098 }
4099 }
4100
4101 // Step 2: move operations from the peeled section down into the
4102 // not-peeled section
4103
4104 // Get a post order schedule of nodes in the peel region
4105 // Result in right-most operand.
4106 scheduled_nodelist(loop, peel, peel_list);
4107
4108 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4109
4110 // For future check for too many new phis
4111 uint old_phi_cnt = 0;
4112 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
4113 Node* use = head->fast_out(j);
4114 if (use->is_Phi()) old_phi_cnt++;
4115 }
4116
4117 #ifndef PRODUCT
4118 if (TracePartialPeeling) {
4119 tty->print_cr("\npeeled list");
4120 }
4121 #endif
4122
4123 // Evacuate nodes in peel region into the not_peeled region if possible
4124 bool too_many_clones = false;
4125 uint new_phi_cnt = 0;
4126 uint cloned_for_outside_use = 0;
4127 for (uint i = 0; i < peel_list.size();) {
4128 Node* n = peel_list.at(i);
4129 #ifndef PRODUCT
4130 if (TracePartialPeeling) n->dump();
4131 #endif
4132 bool incr = true;
4133 if (!n->is_CFG()) {
4134 if (has_use_in_set(n, not_peel)) {
4135 // If not used internal to the peeled region,
4136 // move "n" from peeled to not_peeled region.
4137 if (!has_use_internal_to_set(n, peel, loop)) {
4138 // if not pinned and not a load (which maybe anti-dependent on a store)
4139 // and not a CMove (Matcher expects only bool->cmove).
4140 if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
4141 int new_clones = clone_for_use_outside_loop(loop, n, worklist);
4142 if (C->failing()) return false;
4143 if (new_clones == -1) {
4144 too_many_clones = true;
4145 break;
4146 }
4147 cloned_for_outside_use += new_clones;
4148 sink_list.push(n);
4149 peel.remove(n->_idx);
4150 not_peel.set(n->_idx);
4151 peel_list.remove(i);
4152 incr = false;
4153 #ifndef PRODUCT
4154 if (TracePartialPeeling) {
4155 tty->print_cr("sink to not_peeled region: %d newbb: %d",
4156 n->_idx, get_ctrl(n)->_idx);
4157 }
4158 #endif
4159 }
4160 } else {
4161 // Otherwise check for special def-use cases that span
4162 // the peel/not_peel boundary such as bool->if
4163 clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
4164 new_phi_cnt++;
4165 }
4166 }
4167 }
4168 if (incr) i++;
4169 }
4170
4171 estimate += cloned_for_outside_use + new_phi_cnt;
4172 bool exceed_node_budget = !may_require_nodes(estimate);
4173 bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
4174
4175 if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
4176 #ifndef PRODUCT
4177 if (TracePartialPeeling && exceed_phi_limit) {
4178 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
4179 new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
4180 }
4181 #endif
4182 if (new_peel_if != nullptr) {
4183 remove_cmpi_loop_exit(new_peel_if, loop);
4184 }
4185 // Inhibit more partial peeling on this loop
4186 assert(!head->is_partial_peel_loop(), "not partial peeled");
4187 head->mark_partial_peel_failed();
4188 if (cloned_for_outside_use > 0) {
4189 // Terminate this round of loop opts because
4190 // the graph outside this loop was changed.
4191 C->set_major_progress();
4192 return true;
4193 }
4194 return false;
4195 }
4196
4197 // Step 3: clone loop, retarget control, and insert new phis
4198
4199 // Create new loop head for new phis and to hang
4200 // the nodes being moved (sinked) from the peel region.
4201 LoopNode* new_head = new LoopNode(last_peel, last_peel);
4202 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
4203 _igvn.register_new_node_with_optimizer(new_head);
4204 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
4205 _igvn.replace_input_of(first_not_peeled, 0, new_head);
4206 set_loop(new_head, loop);
4207 loop->_body.push(new_head);
4208 not_peel.set(new_head->_idx);
4209 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
4210 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
4211
4212 while (sink_list.size() > 0) {
4213 Node* n = sink_list.pop();
4214 set_ctrl(n, new_head);
4215 }
4216
4217 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4218
4219 clone_loop(loop, old_new, dd, IgnoreStripMined);
4220
4221 const uint clone_exit_idx = 1;
4222 const uint orig_exit_idx = 2;
4223 assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4224
4225 Node* head_clone = old_new[head->_idx];
4226 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
4227 Node* orig_tail_clone = head_clone->in(2);
4228
4229 // Add phi if "def" node is in peel set and "use" is not
4230
4231 for (uint i = 0; i < peel_list.size(); i++) {
4232 Node *def = peel_list.at(i);
4233 if (!def->is_CFG()) {
4234 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4235 Node *use = def->fast_out(j);
4236 if (has_node(use) && use->in(0) != C->top() &&
4237 (!peel.test(use->_idx) ||
4238 (use->is_Phi() && use->in(0) == head)) ) {
4239 worklist.push(use);
4240 }
4241 }
4242 while( worklist.size() ) {
4243 Node *use = worklist.pop();
4244 for (uint j = 1; j < use->req(); j++) {
4245 Node* n = use->in(j);
4246 if (n == def) {
4247
4248 // "def" is in peel set, "use" is not in peel set
4249 // or "use" is in the entry boundary (a phi) of the peel set
4250
4251 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4252
4253 if ( loop->is_member(get_loop( use_c )) ) {
4254 // use is in loop
4255 if (old_new[use->_idx] != nullptr) { // null for dead code
4256 Node* use_clone = old_new[use->_idx];
4257 _igvn.replace_input_of(use, j, C->top());
4258 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4259 }
4260 } else {
4261 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4262 // use is not in the loop, check if the live range includes the cut
4263 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4264 if (not_peel.test(lp_if->_idx)) {
4265 assert(j == orig_exit_idx, "use from original loop");
4266 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4267 }
4268 }
4269 }
4270 }
4271 }
4272 }
4273 }
4274
4275 // Step 3b: retarget control
4276
4277 // Redirect control to the new loop head if a cloned node in
4278 // the not_peeled region has control that points into the peeled region.
4279 // This necessary because the cloned peeled region will be outside
4280 // the loop.
4281 // from to
4282 // cloned-peeled <---+
4283 // new_head_clone: | <--+
4284 // cloned-not_peeled in(0) in(0)
4285 // orig-peeled
4286
4287 for (uint i = 0; i < loop->_body.size(); i++) {
4288 Node *n = loop->_body.at(i);
4289 if (!n->is_CFG() && n->in(0) != nullptr &&
4290 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4291 Node* n_clone = old_new[n->_idx];
4292 if (n_clone->depends_only_on_test()) {
4293 // If this node depends_only_on_test, it will be rewire to the loop head, which is not the
4294 // correct test
4295 Node* pinned_clone = n_clone->pin_node_under_control();
4296 if (pinned_clone != nullptr) {
4297 register_new_node_with_ctrl_of(pinned_clone, n_clone);
4298 old_new.map(n->_idx, pinned_clone);
4299 _igvn.replace_node(n_clone, pinned_clone);
4300 n_clone = pinned_clone;
4301 }
4302 }
4303 _igvn.replace_input_of(n_clone, 0, new_head_clone);
4304 }
4305 }
4306
4307 // Backedge of the surviving new_head (the clone) is original last_peel
4308 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4309
4310 // Cut first node in original not_peel set
4311 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
4312 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
4313 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
4314
4315 // Copy head_clone back-branch info to original head
4316 // and remove original head's loop entry and
4317 // clone head's back-branch
4318 _igvn.rehash_node_delayed(head); // Multiple edge updates
4319 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
4320 head->set_req(LoopNode::LoopBackControl, C->top());
4321 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4322
4323 // Similarly modify the phis
4324 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4325 Node* use = head->fast_out(k);
4326 if (use->is_Phi() && use->outcnt() > 0) {
4327 Node* use_clone = old_new[use->_idx];
4328 _igvn.rehash_node_delayed(use); // Multiple edge updates
4329 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
4330 use->set_req(LoopNode::LoopBackControl, C->top());
4331 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4332 }
4333 }
4334
4335 // Step 4: update dominator tree and dominator depth
4336
4337 set_idom(head, orig_tail_clone, dd);
4338 recompute_dom_depth();
4339
4340 // Inhibit more partial peeling on this loop
4341 new_head_clone->set_partial_peel_loop();
4342 C->set_major_progress();
4343 loop->record_for_igvn();
4344
4345 #ifndef PRODUCT
4346 if (TracePartialPeeling) {
4347 tty->print_cr("\nafter partial peel one iteration");
4348 Node_List wl;
4349 Node* t = last_peel;
4350 while (true) {
4351 wl.push(t);
4352 if (t == head_clone) break;
4353 t = idom(t);
4354 }
4355 while (wl.size() > 0) {
4356 Node* tt = wl.pop();
4357 if (tt == head) tty->print_cr("orig head");
4358 else if (tt == new_head_clone) tty->print_cr("new head");
4359 else if (tt == head_clone) tty->print_cr("clone head");
4360 tt->dump();
4361 }
4362 }
4363 #endif
4364
4365 C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4366
4367 return true;
4368 }
4369
4370 #ifdef ASSERT
4371
4372 // Moves Template Assertion Predicates to a target loop by cloning and killing the old ones. The target loop is the
4373 // original, not-cloned loop. This is currently only used with StressLoopBackedge which is a develop flag only and
4374 // false with product builds. We can therefore guard it with an ifdef. More details can be found at the use-site.
4375 class MoveAssertionPredicatesVisitor : public PredicateVisitor {
4376 ClonePredicateToTargetLoop _clone_predicate_to_loop;
4377 PhaseIdealLoop* const _phase;
4378
4379 public:
4380 MoveAssertionPredicatesVisitor(LoopNode* target_loop_head,
4381 const NodeInSingleLoopBody &node_in_loop_body,
4382 PhaseIdealLoop* phase)
4383 : _clone_predicate_to_loop(target_loop_head, node_in_loop_body, phase),
4384 _phase(phase) {
4385 }
4386 NONCOPYABLE(MoveAssertionPredicatesVisitor);
4387
4388 using PredicateVisitor::visit;
4389
4390 void visit(const TemplateAssertionPredicate& template_assertion_predicate) override {
4391 _clone_predicate_to_loop.clone_template_assertion_predicate(template_assertion_predicate);
4392 template_assertion_predicate.kill(_phase->igvn());
4393 }
4394 };
4395 #endif // ASSERT
4396
4397 // Transform:
4398 //
4399 // loop<-----------------+
4400 // | |
4401 // stmt1 stmt2 .. stmtn |
4402 // | | | |
4403 // \ | / |
4404 // v v v |
4405 // region |
4406 // | |
4407 // shared_stmt |
4408 // | |
4409 // v |
4410 // if |
4411 // / \ |
4412 // | -----------+
4413 // v
4414 //
4415 // into:
4416 //
4417 // loop<-------------------+
4418 // | |
4419 // v |
4420 // +->loop |
4421 // | | |
4422 // | stmt1 stmt2 .. stmtn |
4423 // | | | | |
4424 // | | \ / |
4425 // | | v v |
4426 // | | region1 |
4427 // | | | |
4428 // | shared_stmt shared_stmt |
4429 // | | | |
4430 // | v v |
4431 // | if if |
4432 // | /\ / \ |
4433 // +-- | | -------+
4434 // \ /
4435 // v v
4436 // region2
4437 //
4438 // (region2 is shown to merge mirrored projections of the loop exit
4439 // ifs to make the diagram clearer but they really merge the same
4440 // projection)
4441 //
4442 // Conditions for this transformation to trigger:
4443 // - the path through stmt1 is frequent enough
4444 // - the inner loop will be turned into a counted loop after transformation
4445 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4446 if (!DuplicateBackedge) {
4447 return false;
4448 }
4449 assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4450 if (!loop->_head->is_Loop()) {
4451 return false;
4452 }
4453
4454 uint estimate = loop->est_loop_clone_sz(1);
4455 if (exceeding_node_budget(estimate)) {
4456 return false;
4457 }
4458
4459 LoopNode *head = loop->_head->as_Loop();
4460
4461 Node* region = nullptr;
4462 IfNode* exit_test = nullptr;
4463 uint inner;
4464 float f;
4465 #ifdef ASSERT
4466 if (StressDuplicateBackedge) {
4467 if (head->is_strip_mined()) {
4468 return false;
4469 }
4470 Node* c = head->in(LoopNode::LoopBackControl);
4471
4472 while (c != head) {
4473 if (c->is_Region()) {
4474 region = c;
4475 }
4476 c = idom(c);
4477 }
4478
4479 if (region == nullptr) {
4480 return false;
4481 }
4482
4483 inner = 1;
4484 } else
4485 #endif //ASSERT
4486 {
4487 // Is the shape of the loop that of a counted loop...
4488 Node* back_control = loop_exit_control(loop);
4489 if (back_control == nullptr) {
4490 return false;
4491 }
4492
4493 LoopExitTest loop_exit(back_control, loop, this);
4494 loop_exit.build();
4495 if (!loop_exit.is_valid_with_bt(T_INT)) {
4496 return false;
4497 }
4498
4499 const Node* loop_incr = loop_exit.incr();
4500
4501 // With an extra phi for the candidate iv?
4502 // Or the region node is the loop head
4503 if (!loop_incr->is_Phi() || loop_incr->in(0) == head) {
4504 return false;
4505 }
4506
4507 PathFrequency pf(head, this);
4508 region = loop_incr->in(0);
4509
4510 // Go over all paths for the extra phi's region and see if that
4511 // path is frequent enough and would match the expected iv shape
4512 // if the extra phi is removed
4513 inner = 0;
4514 for (uint i = 1; i < loop_incr->req(); ++i) {
4515 CountedLoopConverter::TruncatedIncrement increment(T_INT);
4516 increment.build(loop_incr->in(i));
4517 if (!increment.is_valid()) {
4518 continue;
4519 }
4520 assert(increment.incr()->Opcode() == Op_AddI, "wrong increment code");
4521
4522 LoopIVStride stride = LoopIVStride(T_INT);
4523 stride.build(increment.incr());
4524 if (!stride.is_valid()) {
4525 continue;
4526 }
4527
4528 PhiNode* phi = loop_iv_phi(stride.xphi(), nullptr, head);
4529 if (phi == nullptr ||
4530 (increment.outer_trunc() == nullptr && phi->in(LoopNode::LoopBackControl) != loop_exit.incr()) ||
4531 (increment.outer_trunc() != nullptr && phi->in(LoopNode::LoopBackControl) != increment.outer_trunc())) {
4532 return false;
4533 }
4534
4535 f = pf.to(region->in(i));
4536 if (f > 0.5) {
4537 inner = i;
4538 break;
4539 }
4540 }
4541
4542 if (inner == 0) {
4543 return false;
4544 }
4545
4546 exit_test = back_control->in(0)->as_If();
4547 }
4548
4549 if (idom(region)->is_Catch()) {
4550 return false;
4551 }
4552
4553 // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4554 Unique_Node_List wq;
4555 wq.push(head->in(LoopNode::LoopBackControl));
4556 for (uint i = 0; i < wq.size(); i++) {
4557 Node* c = wq.at(i);
4558 assert(get_loop(c) == loop, "not in the right loop?");
4559 if (c->is_Region()) {
4560 if (c != region) {
4561 for (uint j = 1; j < c->req(); ++j) {
4562 wq.push(c->in(j));
4563 }
4564 }
4565 } else {
4566 wq.push(c->in(0));
4567 }
4568 assert(!is_strict_dominator(c, region), "shouldn't go above region");
4569 }
4570
4571 Node* region_dom = idom(region);
4572
4573 // Can't do the transformation if this would cause a membar pair to
4574 // be split
4575 for (uint i = 0; i < wq.size(); i++) {
4576 Node* c = wq.at(i);
4577 if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4578 assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4579 if (!wq.member(c->as_MemBar()->leading_membar())) {
4580 return false;
4581 }
4582 }
4583 }
4584 C->print_method(PHASE_BEFORE_DUPLICATE_LOOP_BACKEDGE, 4, head);
4585
4586 // Collect data nodes that need to be clones as well
4587 int dd = dom_depth(head);
4588
4589 for (uint i = 0; i < loop->_body.size(); ++i) {
4590 Node* n = loop->_body.at(i);
4591 if (has_ctrl(n)) {
4592 Node* c = get_ctrl(n);
4593 if (wq.member(c)) {
4594 wq.push(n);
4595 }
4596 } else {
4597 set_idom(n, idom(n), dd);
4598 }
4599 }
4600
4601 // clone shared_stmt
4602 clone_loop_body(wq, old_new, nullptr);
4603
4604 Node* region_clone = old_new[region->_idx];
4605 region_clone->set_req(inner, C->top());
4606 set_idom(region, region->in(inner), dd);
4607
4608 // Prepare the outer loop
4609 Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4610 register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4611 _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4612 set_idom(head, outer_head, dd);
4613
4614 fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4615
4616 // Make one of the shared_stmt copies only reachable from stmt1, the
4617 // other only from stmt2..stmtn.
4618 Node* dom = nullptr;
4619 for (uint i = 1; i < region->req(); ++i) {
4620 if (i != inner) {
4621 _igvn.replace_input_of(region, i, C->top());
4622 }
4623 Node* in = region_clone->in(i);
4624 if (in->is_top()) {
4625 continue;
4626 }
4627 if (dom == nullptr) {
4628 dom = in;
4629 } else {
4630 dom = dom_lca(dom, in);
4631 }
4632 }
4633
4634 set_idom(region_clone, dom, dd);
4635
4636 // Set up the outer loop
4637 for (uint i = 0; i < head->outcnt(); i++) {
4638 Node* u = head->raw_out(i);
4639 if (u->is_Phi()) {
4640 Node* outer_phi = u->clone();
4641 outer_phi->set_req(0, outer_head);
4642 Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4643 if (backedge == nullptr) {
4644 backedge = u->in(LoopNode::LoopBackControl);
4645 }
4646 outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4647 register_new_node(outer_phi, outer_head);
4648 _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4649 }
4650 }
4651
4652 // create control and data nodes for out of loop uses (including region2)
4653 Node_List worklist;
4654 uint new_counter = C->unique();
4655 fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4656
4657 Node_List *split_if_set = nullptr;
4658 Node_List *split_bool_set = nullptr;
4659 Node_List *split_cex_set = nullptr;
4660 fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4661 split_if_set, split_bool_set, split_cex_set);
4662
4663 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4664
4665 if (exit_test != nullptr) {
4666 float cnt = exit_test->_fcnt;
4667 if (cnt != COUNT_UNKNOWN) {
4668 exit_test->_fcnt = cnt * f;
4669 old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4670 }
4671 }
4672
4673 #ifdef ASSERT
4674 if (StressDuplicateBackedge && head->is_CountedLoop()) {
4675 // The Template Assertion Predicates from the old counted loop are now at the new outer loop - clone them to
4676 // the inner counted loop and kill the old ones. We only need to do this with debug builds because
4677 // StressDuplicateBackedge is a devlop flag and false by default. Without StressDuplicateBackedge 'head' will be a
4678 // non-counted loop, and thus we have no Template Assertion Predicates above the old loop to move down.
4679 PredicateIterator predicate_iterator(outer_head->in(LoopNode::EntryControl));
4680 NodeInSingleLoopBody node_in_body(this, loop);
4681 MoveAssertionPredicatesVisitor move_assertion_predicates_visitor(head, node_in_body, this);
4682 predicate_iterator.for_each(move_assertion_predicates_visitor);
4683 }
4684 #endif // ASSERT
4685
4686 C->set_major_progress();
4687
4688 C->print_method(PHASE_AFTER_DUPLICATE_LOOP_BACKEDGE, 4, outer_head);
4689
4690 return true;
4691 }
4692
4693 // AutoVectorize the loop: replace scalar ops with vector ops.
4694 PhaseIdealLoop::AutoVectorizeStatus
4695 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4696 // Counted loop only
4697 if (!lpt->is_counted()) {
4698 return AutoVectorizeStatus::Impossible;
4699 }
4700
4701 // Main-loop only
4702 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4703 if (!cl->is_main_loop()) {
4704 return AutoVectorizeStatus::Impossible;
4705 }
4706
4707 VLoop vloop(lpt, false);
4708 if (!vloop.check_preconditions()) {
4709 return AutoVectorizeStatus::TriedAndFailed;
4710 }
4711
4712 // Ensure the shared data is cleared before each use
4713 vshared.clear();
4714
4715 const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4716 if (!vloop_analyzer.success()) {
4717 return AutoVectorizeStatus::TriedAndFailed;
4718 }
4719
4720 SuperWord sw(vloop_analyzer);
4721 if (!sw.transform_loop()) {
4722 return AutoVectorizeStatus::TriedAndFailed;
4723 }
4724
4725 return AutoVectorizeStatus::Success;
4726 }
4727
4728 // Just before insert_pre_post_loops, we can multiversion the loop:
4729 //
4730 // multiversion_if
4731 // | |
4732 // fast_loop slow_loop
4733 //
4734 // In the fast_loop we can make speculative assumptions, and put the
4735 // conditions into the multiversion_if. If the conditions hold at runtime,
4736 // we enter the fast_loop, if the conditions fail, we take the slow_loop
4737 // instead which does not make any of the speculative assumptions.
4738 //
4739 // Note: we only multiversion the loop if the loop does not have any
4740 // auto vectorization check Predicate. If we have that predicate,
4741 // then we can simply add the speculative assumption checks to
4742 // that Predicate. This means we do not need to duplicate the
4743 // loop - we have a smaller graph and save compile time. Should
4744 // the conditions ever fail, then we deopt / trap at the Predicate
4745 // and recompile without that Predicate. At that point we will
4746 // multiversion the loop, so that we can still have speculative
4747 // runtime checks.
4748 //
4749 // We perform the multiversioning when the loop is still in its single
4750 // iteration form, even before we insert pre and post loops. This makes
4751 // the cloning much simpler. However, this means that both the fast
4752 // and the slow loop have to be optimized independently (adding pre
4753 // and post loops, unrolling the main loop, auto-vectorize etc.). And
4754 // we may end up not needing any speculative assumptions in the fast_loop
4755 // and then rejecting the slow_loop by constant folding the multiversion_if.
4756 //
4757 // Therefore, we "delay" the optimization of the slow_loop until we add
4758 // at least one speculative assumption for the fast_loop. If we never
4759 // add such a speculative runtime check, the OpaqueMultiversioningNode
4760 // of the multiversion_if constant folds to true after loop opts, and the
4761 // multiversion_if folds away the "delayed" slow_loop. If we add any
4762 // speculative assumption, then we notify the OpaqueMultiversioningNode
4763 // with "notify_slow_loop_that_it_can_resume_optimizations".
4764 //
4765 // Note: new runtime checks can be added to the multiversion_if with
4766 // PhaseIdealLoop::create_new_if_for_multiversion
4767 void PhaseIdealLoop::maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new) {
4768 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4769 LoopNode* outer_loop = cl->skip_strip_mined();
4770 Node* entry = outer_loop->in(LoopNode::EntryControl);
4771
4772 // Check we have multiversioning enabled, and are not already multiversioned.
4773 if (!LoopMultiversioning || cl->is_multiversion()) { return; }
4774
4775 // Check that we do not have a parse-predicate where we can add the runtime checks
4776 // during auto-vectorization.
4777 const Predicates predicates(entry);
4778 const PredicateBlock* predicate_block = predicates.auto_vectorization_check_block();
4779 if (predicate_block->has_parse_predicate()) { return; }
4780
4781 // Check node budget.
4782 uint estimate = lpt->est_loop_clone_sz(2);
4783 if (!may_require_nodes(estimate)) { return; }
4784
4785 do_multiversioning(lpt, old_new);
4786 }
4787
4788 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4789 for (uint i = 0; i < _data_nodes.size(); i++) {
4790 clone(_data_nodes[i], new_ctrl);
4791 }
4792 }
4793
4794 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4795 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4796 Node* clone = node->clone();
4797 _phase->igvn().register_new_node_with_optimizer(clone);
4798 _orig_to_new.put(node, clone);
4799 _phase->set_ctrl(clone, new_ctrl);
4800 if (node->is_CastII()) {
4801 clone->set_req(0, new_ctrl);
4802 }
4803 }
4804
4805 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4806 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4807 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4808 _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4809 for (uint i = 1; i < node->req(); i++) {
4810 Node** cloned_input = _orig_to_new.get(node->in(i));
4811 if (cloned_input != nullptr) {
4812 // Input was also cloned -> rewire clone to the cloned input.
4813 _phase->igvn().replace_input_of(clone, i, *cloned_input);
4814 }
4815 }
4816 });
4817 }
4818
4819 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4820 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4821 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4822 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4823 Node* new_ctrl) {
4824 for (uint i = 0; i < _data_nodes.size(); i++) {
4825 Node* data_node = _data_nodes[i];
4826 if (data_node->is_Opaque1()) {
4827 transform_opaque_node(transform_strategy, data_node);
4828 } else {
4829 clone(data_node, new_ctrl);
4830 }
4831 }
4832 }
4833
4834 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4835 Node* transformed_node;
4836 if (node->is_OpaqueLoopInit()) {
4837 transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4838 } else {
4839 assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4840 transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4841 }
4842 // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4843 _orig_to_new.put(node, transformed_node);
4844 }