1 /*
2 * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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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);
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);
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 pin_array_access_nodes) {
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, pin_array_access_nodes);
397 }
398
399 void PhaseIdealLoop::rewire_safe_outputs_to_dominator(Node* source, Node* dominator, const bool pin_array_access_nodes) {
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 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
405 if (out->depends_only_on_test() && _igvn.no_dependent_zero_check(out)) {
406 assert(out->in(0) == source, "must be control dependent on source");
407 _igvn.replace_input_of(out, 0, dominator);
408 if (pin_array_access_nodes) {
409 // Because of Loop Predication, Loads and range check Cast nodes that are control dependent on this range
410 // check (that is about to be removed) now depend on multiple dominating Hoisted Check Predicates. After the
411 // removal of this range check, these control dependent nodes end up at the lowest/nearest dominating predicate
412 // in the graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
413 // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the lowest
414 // dominating check.
415 Node* clone = out->pin_array_access_node();
416 if (clone != nullptr) {
417 clone = _igvn.register_new_node_with_optimizer(clone, out);
418 _igvn.replace_node(out, clone);
419 out = clone;
420 }
421 }
422 set_early_ctrl(out, false);
423 IdealLoopTree* new_loop = get_loop(get_ctrl(out));
424 if (old_loop != new_loop) {
425 if (!old_loop->_child) {
426 old_loop->_body.yank(out);
427 }
428 if (!new_loop->_child) {
429 new_loop->_body.push(out);
430 }
431 }
432 --i;
433 --imax;
434 }
435 }
436 }
437
438 //------------------------------has_local_phi_input----------------------------
439 // Return TRUE if 'n' has Phi inputs from its local block and no other
440 // block-local inputs (all non-local-phi inputs come from earlier blocks)
441 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
442 Node *n_ctrl = get_ctrl(n);
443 // See if some inputs come from a Phi in this block, or from before
444 // this block.
445 uint i;
446 for( i = 1; i < n->req(); i++ ) {
447 Node *phi = n->in(i);
448 if( phi->is_Phi() && phi->in(0) == n_ctrl )
449 break;
450 }
451 if( i >= n->req() )
452 return nullptr; // No Phi inputs; nowhere to clone thru
453
454 // Check for inputs created between 'n' and the Phi input. These
455 // must split as well; they have already been given the chance
456 // (courtesy of a post-order visit) and since they did not we must
457 // recover the 'cost' of splitting them by being very profitable
458 // when splitting 'n'. Since this is unlikely we simply give up.
459 for( i = 1; i < n->req(); i++ ) {
460 Node *m = n->in(i);
461 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
462 // We allow the special case of AddP's with no local inputs.
463 // This allows us to split-up address expressions.
464 if (m->is_AddP() &&
465 get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
466 get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
467 get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
468 // Move the AddP up to the dominating point. That's fine because control of m's inputs
469 // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
470 Node* c = find_non_split_ctrl(idom(n_ctrl));
471 if (c->is_OuterStripMinedLoop()) {
472 c->as_Loop()->verify_strip_mined(1);
473 c = c->in(LoopNode::EntryControl);
474 }
475 set_ctrl_and_loop(m, c);
476 continue;
477 }
478 return nullptr;
479 }
480 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
481 }
482
483 return n_ctrl;
484 }
485
486 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
487 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
488 assert(bt == T_INT || bt == T_LONG, "only for integers");
489 int n_op = n->Opcode();
490
491 if (n_op == Op_LShift(bt)) {
492 // Scale is loop invariant
493 Node* scale = n->in(2);
494 Node* scale_ctrl = get_ctrl(scale);
495 IdealLoopTree* scale_loop = get_loop(scale_ctrl);
496 if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
497 return nullptr;
498 }
499 const TypeInt* scale_t = scale->bottom_type()->isa_int();
500 if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
501 return nullptr; // Dont bother with byte/short masking
502 }
503 // Add must vary with loop (else shift would be loop-invariant)
504 Node* add = n->in(1);
505 Node* add_ctrl = get_ctrl(add);
506 IdealLoopTree* add_loop = get_loop(add_ctrl);
507 if (n_loop != add_loop) {
508 return nullptr; // happens w/ evil ZKM loops
509 }
510
511 // Convert I-V into I+ (0-V); same for V-I
512 if (add->Opcode() == Op_Sub(bt) &&
513 _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
514 assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
515 Node* zero = integercon(0, bt);
516 Node* neg = SubNode::make(zero, add->in(2), bt);
517 register_new_node_with_ctrl_of(neg, add->in(2));
518 add = AddNode::make(add->in(1), neg, bt);
519 register_new_node(add, add_ctrl);
520 }
521 if (add->Opcode() != Op_Add(bt)) return nullptr;
522 assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
523 // See if one add input is loop invariant
524 Node* add_var = add->in(1);
525 Node* add_var_ctrl = get_ctrl(add_var);
526 IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
527 Node* add_invar = add->in(2);
528 Node* add_invar_ctrl = get_ctrl(add_invar);
529 IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
530 if (add_invar_loop == n_loop) {
531 // Swap to find the invariant part
532 add_invar = add_var;
533 add_invar_ctrl = add_var_ctrl;
534 add_invar_loop = add_var_loop;
535 add_var = add->in(2);
536 } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
537 return nullptr;
538 }
539 if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
540 return nullptr; // No invariant part of the add?
541 }
542
543 // Yes! Reshape address expression!
544 Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
545 Node* inv_scale_ctrl =
546 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
547 add_invar_ctrl : scale_ctrl;
548 register_new_node(inv_scale, inv_scale_ctrl);
549 Node* var_scale = LShiftNode::make(add_var, scale, bt);
550 register_new_node(var_scale, n_ctrl);
551 Node* var_add = AddNode::make(var_scale, inv_scale, bt);
552 register_new_node(var_add, n_ctrl);
553 _igvn.replace_node(n, var_add);
554 return var_add;
555 }
556 return nullptr;
557 }
558
559 //------------------------------remix_address_expressions----------------------
560 // Rework addressing expressions to get the most loop-invariant stuff
561 // moved out. We'd like to do all associative operators, but it's especially
562 // important (common) to do address expressions.
563 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
564 if (!has_ctrl(n)) return nullptr;
565 Node* n_ctrl = get_ctrl(n);
566 IdealLoopTree* n_loop = get_loop(n_ctrl);
567
568 // See if 'n' mixes loop-varying and loop-invariant inputs and
569 // itself is loop-varying.
570
571 // Only interested in binary ops (and AddP)
572 if (n->req() < 3 || n->req() > 4) return nullptr;
573
574 Node* n1_ctrl = get_ctrl(n->in( 1));
575 Node* n2_ctrl = get_ctrl(n->in( 2));
576 Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
577 IdealLoopTree* n1_loop = get_loop(n1_ctrl);
578 IdealLoopTree* n2_loop = get_loop(n2_ctrl);
579 IdealLoopTree* n3_loop = get_loop(n3_ctrl);
580
581 // Does one of my inputs spin in a tighter loop than self?
582 if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
583 (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
584 (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
585 return nullptr; // Leave well enough alone
586 }
587
588 // Is at least one of my inputs loop-invariant?
589 if (n1_loop == n_loop &&
590 n2_loop == n_loop &&
591 n3_loop == n_loop) {
592 return nullptr; // No loop-invariant inputs
593 }
594
595 Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
596 if (res != nullptr) {
597 return res;
598 }
599 res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
600 if (res != nullptr) {
601 return res;
602 }
603
604 int n_op = n->Opcode();
605 // Replace (I+V) with (V+I)
606 if (n_op == Op_AddI ||
607 n_op == Op_AddL ||
608 n_op == Op_AddF ||
609 n_op == Op_AddD ||
610 n_op == Op_MulI ||
611 n_op == Op_MulL ||
612 n_op == Op_MulF ||
613 n_op == Op_MulD) {
614 if (n2_loop == n_loop) {
615 assert(n1_loop != n_loop, "");
616 n->swap_edges(1, 2);
617 }
618 }
619
620 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
621 // but not if I2 is a constant. Skip for irreducible loops.
622 if (n_op == Op_AddP && n_loop->_head->is_Loop()) {
623 if (n2_loop == n_loop && n3_loop != n_loop) {
624 if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
625 Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
626 Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
627 IdealLoopTree* n22loop = get_loop(n22_ctrl);
628 IdealLoopTree* n23_loop = get_loop(n23_ctrl);
629 if (n22loop != n_loop && n22loop->is_member(n_loop) &&
630 n23_loop == n_loop) {
631 Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
632 // Stuff new AddP in the loop preheader
633 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
634 Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
635 register_new_node(add2, n_ctrl);
636 _igvn.replace_node(n, add2);
637 return add2;
638 }
639 }
640 }
641
642 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
643 if (n2_loop != n_loop && n3_loop == n_loop) {
644 if (n->in(3)->Opcode() == Op_AddX) {
645 Node* V = n->in(3)->in(1);
646 Node* I = n->in(3)->in(2);
647 if (is_member(n_loop,get_ctrl(V))) {
648 } else {
649 Node *tmp = V; V = I; I = tmp;
650 }
651 if (!is_member(n_loop,get_ctrl(I))) {
652 Node* add1 = new AddPNode(n->in(1), n->in(2), I);
653 // Stuff new AddP in the loop preheader
654 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
655 Node* add2 = new AddPNode(n->in(1), add1, V);
656 register_new_node(add2, n_ctrl);
657 _igvn.replace_node(n, add2);
658 return add2;
659 }
660 }
661 }
662 }
663
664 return nullptr;
665 }
666
667 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
668 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
669 assert(n->Opcode() == Op_AddI, "sanity");
670 Node * nn = nullptr;
671 Node * in1 = n->in(1);
672 Node * in2 = n->in(2);
673 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
674 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
675 if (loop_n->is_counted() &&
676 loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
677 Matcher::match_rule_supported(Op_MulAddVS2VI) &&
678 Matcher::match_rule_supported(Op_MulAddS2I)) {
679 Node* mul_in1 = in1->in(1);
680 Node* mul_in2 = in1->in(2);
681 Node* mul_in3 = in2->in(1);
682 Node* mul_in4 = in2->in(2);
683 if (mul_in1->Opcode() == Op_LoadS &&
684 mul_in2->Opcode() == Op_LoadS &&
685 mul_in3->Opcode() == Op_LoadS &&
686 mul_in4->Opcode() == Op_LoadS) {
687 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
688 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
689 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
690 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
691 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
692 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
693 // All nodes should be in the same counted loop.
694 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
695 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
696 Node* adr1 = mul_in1->in(MemNode::Address);
697 Node* adr2 = mul_in2->in(MemNode::Address);
698 Node* adr3 = mul_in3->in(MemNode::Address);
699 Node* adr4 = mul_in4->in(MemNode::Address);
700 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
701 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
702 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
703 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
704 register_new_node_with_ctrl_of(nn, n);
705 _igvn.replace_node(n, nn);
706 return nn;
707 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
708 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
709 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
710 register_new_node_with_ctrl_of(nn, n);
711 _igvn.replace_node(n, nn);
712 return nn;
713 }
714 }
715 }
716 }
717 }
718 }
719 return nn;
720 }
721
722 //------------------------------conditional_move-------------------------------
723 // Attempt to replace a Phi with a conditional move. We have some pretty
724 // strict profitability requirements. All Phis at the merge point must
725 // be converted, so we can remove the control flow. We need to limit the
726 // number of c-moves to a small handful. All code that was in the side-arms
727 // of the CFG diamond is now speculatively executed. This code has to be
728 // "cheap enough". We are pretty much limited to CFG diamonds that merge
729 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
730 Node *PhaseIdealLoop::conditional_move( Node *region ) {
731
732 assert(region->is_Region(), "sanity check");
733 if (region->req() != 3) return nullptr;
734
735 // Check for CFG diamond
736 Node *lp = region->in(1);
737 Node *rp = region->in(2);
738 if (!lp || !rp) return nullptr;
739 Node *lp_c = lp->in(0);
740 if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
741 IfNode *iff = lp_c->as_If();
742
743 // Check for ops pinned in an arm of the diamond.
744 // Can't remove the control flow in this case
745 if (lp->outcnt() > 1) return nullptr;
746 if (rp->outcnt() > 1) return nullptr;
747
748 IdealLoopTree* r_loop = get_loop(region);
749 assert(r_loop == get_loop(iff), "sanity");
750 // Always convert to CMOVE if all results are used only outside this loop.
751 bool used_inside_loop = (r_loop == _ltree_root);
752
753 // Check profitability
754 int cost = 0;
755 int phis = 0;
756 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
757 Node *out = region->fast_out(i);
758 if (!out->is_Phi()) continue; // Ignore other control edges, etc
759 phis++;
760 PhiNode* phi = out->as_Phi();
761 BasicType bt = phi->type()->basic_type();
762 switch (bt) {
763 case T_DOUBLE:
764 case T_FLOAT:
765 if (C->use_cmove()) {
766 continue; //TODO: maybe we want to add some cost
767 }
768 cost += Matcher::float_cmove_cost(); // Could be very expensive
769 break;
770 case T_LONG: {
771 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
772 }
773 case T_INT: // These all CMOV fine
774 case T_ADDRESS: { // (RawPtr)
775 cost++;
776 break;
777 }
778 case T_NARROWOOP: // Fall through
779 case T_OBJECT: { // Base oops are OK, but not derived oops
780 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
781 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
782 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
783 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
784 // have a Phi for the base here that we convert to a CMOVE all is well
785 // and good. But if the base is dead, we'll not make a CMOVE. Later
786 // the allocator will have to produce a base by creating a CMOVE of the
787 // relevant bases. This puts the allocator in the business of
788 // manufacturing expensive instructions, generally a bad plan.
789 // Just Say No to Conditionally-Moved Derived Pointers.
790 if (tp && tp->offset() != 0)
791 return nullptr;
792 cost++;
793 break;
794 }
795 default:
796 return nullptr; // In particular, can't do memory or I/O
797 }
798 // Add in cost any speculative ops
799 for (uint j = 1; j < region->req(); j++) {
800 Node *proj = region->in(j);
801 Node *inp = phi->in(j);
802 if (inp->isa_InlineType()) {
803 // TODO 8302217 This prevents PhiNode::push_inline_types_through
804 return nullptr;
805 }
806 if (get_ctrl(inp) == proj) { // Found local op
807 cost++;
808 // Check for a chain of dependent ops; these will all become
809 // speculative in a CMOV.
810 for (uint k = 1; k < inp->req(); k++)
811 if (get_ctrl(inp->in(k)) == proj)
812 cost += ConditionalMoveLimit; // Too much speculative goo
813 }
814 }
815 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
816 // This will likely Split-If, a higher-payoff operation.
817 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
818 Node* use = phi->fast_out(k);
819 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
820 cost += ConditionalMoveLimit;
821 // Is there a use inside the loop?
822 // Note: check only basic types since CMoveP is pinned.
823 if (!used_inside_loop && is_java_primitive(bt)) {
824 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
825 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
826 used_inside_loop = true;
827 }
828 }
829 }
830 }//for
831 Node* bol = iff->in(1);
832 assert(!bol->is_OpaqueInitializedAssertionPredicate(), "Initialized Assertion Predicates cannot form a diamond with Halt");
833 if (bol->is_OpaqueTemplateAssertionPredicate()) {
834 // Ignore Template Assertion Predicates with OpaqueTemplateAssertionPredicate nodes.
835 return nullptr;
836 }
837 if (bol->is_OpaqueMultiversioning()) {
838 assert(bol->as_OpaqueMultiversioning()->is_useless(), "Must be useless, i.e. fast main loop has already disappeared.");
839 // Ignore multiversion_if that just lost its loops. The OpaqueMultiversioning is marked useless,
840 // and will make the multiversion_if constant fold in the next IGVN round.
841 return nullptr;
842 }
843 if (!bol->is_Bool()) {
844 assert(false, "Expected Bool, but got %s", NodeClassNames[bol->Opcode()]);
845 return nullptr;
846 }
847 int cmp_op = bol->in(1)->Opcode();
848 if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
849 return nullptr;
850 }
851 // It is expensive to generate flags from a float compare.
852 // Avoid duplicated float compare.
853 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
854
855 float infrequent_prob = PROB_UNLIKELY_MAG(3);
856 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
857 if (used_inside_loop) {
858 if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
859
860 // BlockLayoutByFrequency optimization moves infrequent branch
861 // from hot path. No point in CMOV'ing in such case (110 is used
862 // instead of 100 to take into account not exactness of float value).
863 if (BlockLayoutByFrequency) {
864 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
865 }
866 }
867 // Check for highly predictable branch. No point in CMOV'ing if
868 // we are going to predict accurately all the time.
869 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
870 //keep going
871 } else if (iff->_prob < infrequent_prob ||
872 iff->_prob > (1.0f - infrequent_prob))
873 return nullptr;
874
875 // --------------
876 // Now replace all Phis with CMOV's
877 Node *cmov_ctrl = iff->in(0);
878 uint flip = (lp->Opcode() == Op_IfTrue);
879 Node_List wq;
880 while (1) {
881 PhiNode* phi = nullptr;
882 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
883 Node *out = region->fast_out(i);
884 if (out->is_Phi()) {
885 phi = out->as_Phi();
886 break;
887 }
888 }
889 if (phi == nullptr || _igvn.type(phi) == Type::TOP || !CMoveNode::supported(_igvn.type(phi))) {
890 break;
891 }
892 // Move speculative ops
893 wq.push(phi);
894 while (wq.size() > 0) {
895 Node *n = wq.pop();
896 for (uint j = 1; j < n->req(); j++) {
897 Node* m = n->in(j);
898 if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
899 set_ctrl(m, cmov_ctrl);
900 wq.push(m);
901 }
902 }
903 }
904 Node* cmov = CMoveNode::make(iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
905 register_new_node(cmov, cmov_ctrl);
906 _igvn.replace_node(phi, cmov);
907 #ifndef PRODUCT
908 if (TraceLoopOpts) {
909 tty->print("CMOV ");
910 r_loop->dump_head();
911 if (Verbose) {
912 bol->in(1)->dump(1);
913 cmov->dump(1);
914 }
915 }
916 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
917 #endif
918 }
919
920 // The useless CFG diamond will fold up later; see the optimization in
921 // RegionNode::Ideal.
922 _igvn._worklist.push(region);
923
924 return iff->in(1);
925 }
926
927 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
928 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
929 Node* u = m->fast_out(i);
930 if (u->is_CFG()) {
931 if (u->is_NeverBranch()) {
932 u = u->as_NeverBranch()->proj_out(0);
933 enqueue_cfg_uses(u, wq);
934 } else {
935 wq.push(u);
936 }
937 }
938 }
939 }
940
941 // Try moving a store out of a loop, right before the loop
942 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
943 // Store has to be first in the loop body
944 IdealLoopTree *n_loop = get_loop(n_ctrl);
945 if (n->is_Store() && n_loop != _ltree_root &&
946 n_loop->is_loop() && n_loop->_head->is_Loop() &&
947 n->in(0) != nullptr) {
948 Node* address = n->in(MemNode::Address);
949 Node* value = n->in(MemNode::ValueIn);
950 Node* mem = n->in(MemNode::Memory);
951 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
952 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
953
954 // - address and value must be loop invariant
955 // - memory must be a memory Phi for the loop
956 // - Store must be the only store on this memory slice in the
957 // loop: if there's another store following this one then value
958 // written at iteration i by the second store could be overwritten
959 // at iteration i+n by the first store: it's not safe to move the
960 // first store out of the loop
961 // - nothing must observe the memory Phi: it guarantees no read
962 // before the store, we are also guaranteed the store post
963 // dominates the loop head (ignoring a possible early
964 // exit). Otherwise there would be extra Phi involved between the
965 // loop's Phi and the store.
966 // - there must be no early exit from the loop before the Store
967 // (such an exit most of the time would be an extra use of the
968 // memory Phi but sometimes is a bottom memory Phi that takes the
969 // store as input).
970
971 if (!n_loop->is_member(address_loop) &&
972 !n_loop->is_member(value_loop) &&
973 mem->is_Phi() && mem->in(0) == n_loop->_head &&
974 mem->outcnt() == 1 &&
975 mem->in(LoopNode::LoopBackControl) == n) {
976
977 assert(n_loop->_tail != nullptr, "need a tail");
978 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
979
980 // Verify that there's no early exit of the loop before the store.
981 bool ctrl_ok = false;
982 {
983 // Follow control from loop head until n, we exit the loop or
984 // we reach the tail
985 ResourceMark rm;
986 Unique_Node_List wq;
987 wq.push(n_loop->_head);
988
989 for (uint next = 0; next < wq.size(); ++next) {
990 Node *m = wq.at(next);
991 if (m == n->in(0)) {
992 ctrl_ok = true;
993 continue;
994 }
995 assert(!has_ctrl(m), "should be CFG");
996 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
997 ctrl_ok = false;
998 break;
999 }
1000 enqueue_cfg_uses(m, wq);
1001 if (wq.size() > 10) {
1002 ctrl_ok = false;
1003 break;
1004 }
1005 }
1006 }
1007 if (ctrl_ok) {
1008 // move the Store
1009 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
1010 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
1011 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
1012 // Disconnect the phi now. An empty phi can confuse other
1013 // optimizations in this pass of loop opts.
1014 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
1015 n_loop->_body.yank(mem);
1016
1017 set_ctrl_and_loop(n, n->in(0));
1018
1019 return n;
1020 }
1021 }
1022 }
1023 return nullptr;
1024 }
1025
1026 // Try moving a store out of a loop, right after the loop
1027 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
1028 if (n->is_Store() && n->in(0) != nullptr) {
1029 Node *n_ctrl = get_ctrl(n);
1030 IdealLoopTree *n_loop = get_loop(n_ctrl);
1031 // Store must be in a loop
1032 if (n_loop != _ltree_root && !n_loop->_irreducible) {
1033 Node* address = n->in(MemNode::Address);
1034 Node* value = n->in(MemNode::ValueIn);
1035 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
1036 // address must be loop invariant
1037 if (!n_loop->is_member(address_loop)) {
1038 // Store must be last on this memory slice in the loop and
1039 // nothing in the loop must observe it
1040 Node* phi = nullptr;
1041 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1042 Node* u = n->fast_out(i);
1043 if (has_ctrl(u)) { // control use?
1044 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1045 if (!n_loop->is_member(u_loop)) {
1046 continue;
1047 }
1048 if (u->is_Phi() && u->in(0) == n_loop->_head) {
1049 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1050 // multiple phis on the same slice are possible
1051 if (phi != nullptr) {
1052 return;
1053 }
1054 phi = u;
1055 continue;
1056 }
1057 }
1058 return;
1059 }
1060 if (phi != nullptr) {
1061 // Nothing in the loop before the store (next iteration)
1062 // must observe the stored value
1063 bool mem_ok = true;
1064 {
1065 ResourceMark rm;
1066 Unique_Node_List wq;
1067 wq.push(phi);
1068 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1069 Node *m = wq.at(next);
1070 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1071 Node* u = m->fast_out(i);
1072 if (u->is_Store() || u->is_Phi()) {
1073 if (u != n) {
1074 wq.push(u);
1075 mem_ok = (wq.size() <= 10);
1076 }
1077 } else {
1078 mem_ok = false;
1079 break;
1080 }
1081 }
1082 }
1083 }
1084 if (mem_ok) {
1085 // Move the store out of the loop if the LCA of all
1086 // users (except for the phi) is outside the loop.
1087 Node* hook = new Node(1);
1088 hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1089 _igvn.rehash_node_delayed(phi);
1090 int count = phi->replace_edge(n, hook, &_igvn);
1091 assert(count > 0, "inconsistent phi");
1092
1093 // Compute latest point this store can go
1094 Node* lca = get_late_ctrl(n, get_ctrl(n));
1095 if (lca->is_OuterStripMinedLoop()) {
1096 lca = lca->in(LoopNode::EntryControl);
1097 }
1098 if (n_loop->is_member(get_loop(lca))) {
1099 // LCA is in the loop - bail out
1100 _igvn.replace_node(hook, n);
1101 return;
1102 }
1103 #ifdef ASSERT
1104 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1105 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1106 n_loop->_head->as_Loop()->verify_strip_mined(1);
1107 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1108 IdealLoopTree* outer_loop = get_loop(outer);
1109 assert(n_loop->_parent == outer_loop, "broken loop tree");
1110 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1111 }
1112 #endif
1113 lca = place_outside_loop(lca, n_loop);
1114 assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1115 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");
1116
1117 // Move store out of the loop
1118 _igvn.replace_node(hook, n->in(MemNode::Memory));
1119 _igvn.replace_input_of(n, 0, lca);
1120 set_ctrl_and_loop(n, lca);
1121
1122 // Disconnect the phi now. An empty phi can confuse other
1123 // optimizations in this pass of loop opts..
1124 if (phi->in(LoopNode::LoopBackControl) == phi) {
1125 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1126 n_loop->_body.yank(phi);
1127 }
1128 }
1129 }
1130 }
1131 }
1132 }
1133 }
1134
1135 // We can't use immutable memory for the flat array check because we are loading the mark word which is
1136 // mutable. Although the bits we are interested in are immutable (we check for markWord::unlocked_value),
1137 // we need to use raw memory to not break anti dependency analysis. Below code will attempt to still move
1138 // flat array checks out of loops, mainly to enable loop unswitching.
1139 void PhaseIdealLoop::move_flat_array_check_out_of_loop(Node* n) {
1140 // Skip checks for more than one array
1141 if (n->req() > 3) {
1142 return;
1143 }
1144 Node* mem = n->in(FlatArrayCheckNode::Memory);
1145 Node* array = n->in(FlatArrayCheckNode::ArrayOrKlass)->uncast();
1146 IdealLoopTree* check_loop = get_loop(get_ctrl(n));
1147 IdealLoopTree* ary_loop = get_loop(get_ctrl(array));
1148
1149 // Check if array is loop invariant
1150 if (!check_loop->is_member(ary_loop)) {
1151 // Walk up memory graph from the check until we leave the loop
1152 VectorSet wq;
1153 wq.set(mem->_idx);
1154 while (check_loop->is_member(get_loop(ctrl_or_self(mem)))) {
1155 if (mem->is_Phi()) {
1156 mem = mem->in(1);
1157 } else if (mem->is_MergeMem()) {
1158 mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
1159 } else if (mem->is_Proj()) {
1160 mem = mem->in(0);
1161 } else if (mem->is_MemBar() || mem->is_SafePoint()) {
1162 mem = mem->in(TypeFunc::Memory);
1163 } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
1164 mem = mem->in(MemNode::Memory);
1165 } else {
1166 #ifdef ASSERT
1167 mem->dump();
1168 #endif
1169 ShouldNotReachHere();
1170 }
1171 if (wq.test_set(mem->_idx)) {
1172 return;
1173 }
1174 }
1175 // Replace memory input and re-compute ctrl to move the check out of the loop
1176 _igvn.replace_input_of(n, 1, mem);
1177 set_ctrl_and_loop(n, get_early_ctrl(n));
1178 Node* bol = n->unique_out();
1179 set_ctrl_and_loop(bol, get_early_ctrl(bol));
1180 }
1181 }
1182
1183 //------------------------------split_if_with_blocks_pre-----------------------
1184 // Do the real work in a non-recursive function. Data nodes want to be
1185 // cloned in the pre-order so they can feed each other nicely.
1186 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1187 // Cloning these guys is unlikely to win
1188 int n_op = n->Opcode();
1189 if (n_op == Op_MergeMem) {
1190 return n;
1191 }
1192 if (n->is_Proj()) {
1193 return n;
1194 }
1195
1196 if (n->isa_FlatArrayCheck()) {
1197 move_flat_array_check_out_of_loop(n);
1198 return n;
1199 }
1200
1201 // Do not clone-up CmpFXXX variations, as these are always
1202 // followed by a CmpI
1203 if (n->is_Cmp()) {
1204 return n;
1205 }
1206 // Attempt to use a conditional move instead of a phi/branch
1207 if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1208 Node *cmov = conditional_move( n );
1209 if (cmov) {
1210 return cmov;
1211 }
1212 }
1213 if (n->is_CFG() || n->is_LoadStore()) {
1214 return n;
1215 }
1216 if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1217 if (!C->major_progress()) { // If chance of no more loop opts...
1218 _igvn._worklist.push(n); // maybe we'll remove them
1219 }
1220 return n;
1221 }
1222
1223 if (n->is_Con()) {
1224 return n; // No cloning for Con nodes
1225 }
1226
1227 Node *n_ctrl = get_ctrl(n);
1228 if (!n_ctrl) {
1229 return n; // Dead node
1230 }
1231
1232 Node* res = try_move_store_before_loop(n, n_ctrl);
1233 if (res != nullptr) {
1234 return n;
1235 }
1236
1237 // Attempt to remix address expressions for loop invariants
1238 Node *m = remix_address_expressions( n );
1239 if( m ) return m;
1240
1241 if (n_op == Op_AddI) {
1242 Node *nn = convert_add_to_muladd( n );
1243 if ( nn ) return nn;
1244 }
1245
1246 if (n->is_ConstraintCast()) {
1247 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1248 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1249 // Node control inputs don't necessarily agree with loop control info (due to
1250 // transformations happened in between), thus additional dominance check is needed
1251 // to keep loop info valid.
1252 if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1253 _igvn.replace_node(n, dom_cast);
1254 return dom_cast;
1255 }
1256 }
1257
1258 // Determine if the Node has inputs from some local Phi.
1259 // Returns the block to clone thru.
1260 Node *n_blk = has_local_phi_input( n );
1261 if( !n_blk ) return n;
1262
1263 // Do not clone the trip counter through on a CountedLoop
1264 // (messes up the canonical shape).
1265 if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1266 (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1267 return n;
1268 }
1269 // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1270 if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1271 n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1272 return n;
1273 }
1274
1275 // Check for having no control input; not pinned. Allow
1276 // dominating control.
1277 if (n->in(0)) {
1278 Node *dom = idom(n_blk);
1279 if (dom_lca(n->in(0), dom) != n->in(0)) {
1280 return n;
1281 }
1282 }
1283 // Policy: when is it profitable. You must get more wins than
1284 // policy before it is considered profitable. Policy is usually 0,
1285 // so 1 win is considered profitable. Big merges will require big
1286 // cloning, so get a larger policy.
1287 int policy = n_blk->req() >> 2;
1288
1289 // If the loop is a candidate for range check elimination,
1290 // delay splitting through it's phi until a later loop optimization
1291 if (n_blk->is_BaseCountedLoop()) {
1292 IdealLoopTree *lp = get_loop(n_blk);
1293 if (lp && lp->_rce_candidate) {
1294 return n;
1295 }
1296 }
1297
1298 if (must_throttle_split_if()) return n;
1299
1300 // Split 'n' through the merge point if it is profitable, replacing it with a new phi.
1301 Node* phi = split_thru_phi(n, n_blk, policy);
1302 if (phi == nullptr) { return n; }
1303
1304 // Moved a load around the loop, 'en-registering' something.
1305 if (n_blk->is_Loop() && n->is_Load() &&
1306 !phi->in(LoopNode::LoopBackControl)->is_Load())
1307 C->set_major_progress();
1308
1309 return phi;
1310 }
1311
1312 static bool merge_point_too_heavy(Compile* C, Node* region) {
1313 // Bail out if the region and its phis have too many users.
1314 int weight = 0;
1315 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1316 weight += region->fast_out(i)->outcnt();
1317 }
1318 int nodes_left = C->max_node_limit() - C->live_nodes();
1319 if (weight * 8 > nodes_left) {
1320 if (PrintOpto) {
1321 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1322 }
1323 return true;
1324 } else {
1325 return false;
1326 }
1327 }
1328
1329 static bool merge_point_safe(Node* region) {
1330 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1331 // having a PhiNode input. This sidesteps the dangerous case where the split
1332 // ConvI2LNode may become TOP if the input Value() does not
1333 // overlap the ConvI2L range, leaving a node which may not dominate its
1334 // uses.
1335 // A better fix for this problem can be found in the BugTraq entry, but
1336 // expediency for Mantis demands this hack.
1337 #ifdef _LP64
1338 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1339 Node* n = region->fast_out(i);
1340 if (n->is_Phi()) {
1341 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1342 Node* m = n->fast_out(j);
1343 if (m->Opcode() == Op_ConvI2L)
1344 return false;
1345 if (m->is_CastII()) {
1346 return false;
1347 }
1348 }
1349 }
1350 }
1351 #endif
1352 return true;
1353 }
1354
1355
1356 //------------------------------place_outside_loop---------------------------------
1357 // Place some computation outside of this loop on the path to the use passed as argument
1358 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1359 Node* head = loop->_head;
1360 assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1361 if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1362 loop = loop->_parent;
1363 assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1364 }
1365
1366 // Pick control right outside the loop
1367 for (;;) {
1368 Node* dom = idom(useblock);
1369 if (loop->is_member(get_loop(dom))) {
1370 break;
1371 }
1372 useblock = dom;
1373 }
1374 assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1375 return useblock;
1376 }
1377
1378
1379 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1380 if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1381 return false;
1382 }
1383 if (!n->in(0)->is_Region()) {
1384 return false;
1385 }
1386
1387 Node* region = n->in(0);
1388 Node* dom = idom(region);
1389 if (!dom->is_If() || !n->as_If()->same_condition(dom, &_igvn)) {
1390 return false;
1391 }
1392 IfNode* dom_if = dom->as_If();
1393 Node* proj_true = dom_if->proj_out(1);
1394 Node* proj_false = dom_if->proj_out(0);
1395
1396 for (uint i = 1; i < region->req(); i++) {
1397 if (is_dominator(proj_true, region->in(i))) {
1398 continue;
1399 }
1400 if (is_dominator(proj_false, region->in(i))) {
1401 continue;
1402 }
1403 return false;
1404 }
1405
1406 return true;
1407 }
1408
1409
1410 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1411 if (must_throttle_split_if()) {
1412 return false;
1413 }
1414
1415 // Do not do 'split-if' if irreducible loops are present.
1416 if (_has_irreducible_loops) {
1417 return false;
1418 }
1419
1420 if (merge_point_too_heavy(C, n_ctrl)) {
1421 return false;
1422 }
1423
1424 // Do not do 'split-if' if some paths are dead. First do dead code
1425 // elimination and then see if its still profitable.
1426 for (uint i = 1; i < n_ctrl->req(); i++) {
1427 if (n_ctrl->in(i) == C->top()) {
1428 return false;
1429 }
1430 }
1431
1432 // If trying to do a 'Split-If' at the loop head, it is only
1433 // profitable if the cmp folds up on BOTH paths. Otherwise we
1434 // risk peeling a loop forever.
1435
1436 // CNC - Disabled for now. Requires careful handling of loop
1437 // body selection for the cloned code. Also, make sure we check
1438 // for any input path not being in the same loop as n_ctrl. For
1439 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1440 // because the alternative loop entry points won't be converted
1441 // into LoopNodes.
1442 IdealLoopTree *n_loop = get_loop(n_ctrl);
1443 for (uint j = 1; j < n_ctrl->req(); j++) {
1444 if (get_loop(n_ctrl->in(j)) != n_loop) {
1445 return false;
1446 }
1447 }
1448
1449 // Check for safety of the merge point.
1450 if (!merge_point_safe(n_ctrl)) {
1451 return false;
1452 }
1453
1454 return true;
1455 }
1456
1457 // Detect if the node is the inner strip-mined loop
1458 // Return: null if it's not the case, or the exit of outer strip-mined loop
1459 static Node* is_inner_of_stripmined_loop(const Node* out) {
1460 Node* out_le = nullptr;
1461
1462 if (out->is_CountedLoopEnd()) {
1463 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1464
1465 if (loop != nullptr && loop->is_strip_mined()) {
1466 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1467 }
1468 }
1469
1470 return out_le;
1471 }
1472
1473 bool PhaseIdealLoop::flat_array_element_type_check(Node *n) {
1474 // If the CmpP is a subtype check for a value that has just been
1475 // loaded from an array, the subtype check guarantees the value
1476 // can't be stored in a flat array and the load of the value
1477 // happens with a flat array check then: push the type check
1478 // through the phi of the flat array check. This needs special
1479 // logic because the subtype check's input is not a phi but a
1480 // LoadKlass that must first be cloned through the phi.
1481 if (n->Opcode() != Op_CmpP) {
1482 return false;
1483 }
1484
1485 Node* klassptr = n->in(1);
1486 Node* klasscon = n->in(2);
1487
1488 if (klassptr->is_DecodeNarrowPtr()) {
1489 klassptr = klassptr->in(1);
1490 }
1491
1492 if (klassptr->Opcode() != Op_LoadKlass && klassptr->Opcode() != Op_LoadNKlass) {
1493 return false;
1494 }
1495
1496 if (!klasscon->is_Con()) {
1497 return false;
1498 }
1499
1500 Node* addr = klassptr->in(MemNode::Address);
1501
1502 if (!addr->is_AddP()) {
1503 return false;
1504 }
1505
1506 intptr_t offset;
1507 Node* obj = AddPNode::Ideal_base_and_offset(addr, &_igvn, offset);
1508
1509 if (obj == nullptr) {
1510 return false;
1511 }
1512
1513 assert(obj != nullptr && addr->in(AddPNode::Base) == addr->in(AddPNode::Address), "malformed AddP?");
1514 if (obj->Opcode() == Op_CastPP) {
1515 obj = obj->in(1);
1516 }
1517
1518 if (!obj->is_Phi()) {
1519 return false;
1520 }
1521
1522 Node* region = obj->in(0);
1523
1524 Node* phi = PhiNode::make_blank(region, n->in(1));
1525 for (uint i = 1; i < region->req(); i++) {
1526 Node* in = obj->in(i);
1527 Node* ctrl = region->in(i);
1528 if (addr->in(AddPNode::Base) != obj) {
1529 Node* cast = addr->in(AddPNode::Base);
1530 assert(cast->Opcode() == Op_CastPP && cast->in(0) != nullptr, "inconsistent subgraph");
1531 Node* cast_clone = cast->clone();
1532 cast_clone->set_req(0, ctrl);
1533 cast_clone->set_req(1, in);
1534 register_new_node(cast_clone, ctrl);
1535 const Type* tcast = cast_clone->Value(&_igvn);
1536 _igvn.set_type(cast_clone, tcast);
1537 cast_clone->as_Type()->set_type(tcast);
1538 in = cast_clone;
1539 }
1540 Node* addr_clone = addr->clone();
1541 addr_clone->set_req(AddPNode::Base, in);
1542 addr_clone->set_req(AddPNode::Address, in);
1543 register_new_node(addr_clone, ctrl);
1544 _igvn.set_type(addr_clone, addr_clone->Value(&_igvn));
1545 Node* klassptr_clone = klassptr->clone();
1546 klassptr_clone->set_req(2, addr_clone);
1547 register_new_node(klassptr_clone, ctrl);
1548 _igvn.set_type(klassptr_clone, klassptr_clone->Value(&_igvn));
1549 if (klassptr != n->in(1)) {
1550 Node* decode = n->in(1);
1551 assert(decode->is_DecodeNarrowPtr(), "inconsistent subgraph");
1552 Node* decode_clone = decode->clone();
1553 decode_clone->set_req(1, klassptr_clone);
1554 register_new_node(decode_clone, ctrl);
1555 _igvn.set_type(decode_clone, decode_clone->Value(&_igvn));
1556 klassptr_clone = decode_clone;
1557 }
1558 phi->set_req(i, klassptr_clone);
1559 }
1560 register_new_node(phi, region);
1561 Node* orig = n->in(1);
1562 _igvn.replace_input_of(n, 1, phi);
1563 split_if_with_blocks_post(n);
1564 if (n->outcnt() != 0) {
1565 _igvn.replace_input_of(n, 1, orig);
1566 _igvn.remove_dead_node(phi);
1567 }
1568 return true;
1569 }
1570
1571 //------------------------------split_if_with_blocks_post----------------------
1572 // Do the real work in a non-recursive function. CFG hackery wants to be
1573 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1574 // info.
1575 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1576
1577 if (flat_array_element_type_check(n)) {
1578 return;
1579 }
1580
1581 // Cloning Cmp through Phi's involves the split-if transform.
1582 // FastLock is not used by an If
1583 if (n->is_Cmp() && !n->is_FastLock()) {
1584 Node *n_ctrl = get_ctrl(n);
1585 // Determine if the Node has inputs from some local Phi.
1586 // Returns the block to clone thru.
1587 Node *n_blk = has_local_phi_input(n);
1588 if (n_blk != n_ctrl) {
1589 return;
1590 }
1591
1592 if (!can_split_if(n_ctrl)) {
1593 return;
1594 }
1595
1596 if (n->outcnt() != 1) {
1597 return; // Multiple bool's from 1 compare?
1598 }
1599 Node *bol = n->unique_out();
1600 assert(bol->is_Bool(), "expect a bool here");
1601 if (bol->outcnt() != 1) {
1602 return;// Multiple branches from 1 compare?
1603 }
1604 Node *iff = bol->unique_out();
1605
1606 // Check some safety conditions
1607 if (iff->is_If()) { // Classic split-if?
1608 if (iff->in(0) != n_ctrl) {
1609 return; // Compare must be in same blk as if
1610 }
1611 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1612 // Can't split CMove with different control.
1613 if (get_ctrl(iff) != n_ctrl) {
1614 return;
1615 }
1616 if (get_ctrl(iff->in(2)) == n_ctrl ||
1617 get_ctrl(iff->in(3)) == n_ctrl) {
1618 return; // Inputs not yet split-up
1619 }
1620 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1621 return; // Loop-invar test gates loop-varying CMOVE
1622 }
1623 } else {
1624 return; // some other kind of node, such as an Allocate
1625 }
1626
1627 // When is split-if profitable? Every 'win' on means some control flow
1628 // goes dead, so it's almost always a win.
1629 int policy = 0;
1630 // Split compare 'n' through the merge point if it is profitable
1631 Node *phi = split_thru_phi( n, n_ctrl, policy);
1632 if (!phi) {
1633 return;
1634 }
1635
1636 // Now split the bool up thru the phi
1637 Node* bolphi = split_thru_phi(bol, n_ctrl, -1);
1638 guarantee(bolphi != nullptr, "null boolean phi node");
1639 assert(iff->in(1) == bolphi, "");
1640
1641 if (bolphi->Value(&_igvn)->singleton()) {
1642 return;
1643 }
1644
1645 // Conditional-move? Must split up now
1646 if (!iff->is_If()) {
1647 Node* cmovphi = split_thru_phi(iff, n_ctrl, -1);
1648 return;
1649 }
1650
1651 // Now split the IF
1652 C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1653 if (TraceLoopOpts) {
1654 tty->print_cr("Split-If");
1655 }
1656 do_split_if(iff);
1657 C->print_method(PHASE_AFTER_SPLIT_IF, 4, iff);
1658 return;
1659 }
1660
1661 // Two identical ifs back to back can be merged
1662 if (try_merge_identical_ifs(n)) {
1663 return;
1664 }
1665
1666 // Check for an IF ready to split; one that has its
1667 // condition codes input coming from a Phi at the block start.
1668 int n_op = n->Opcode();
1669
1670 // Check for an IF being dominated by another IF same test
1671 if (n_op == Op_If ||
1672 n_op == Op_RangeCheck) {
1673 Node *bol = n->in(1);
1674 uint max = bol->outcnt();
1675 // Check for same test used more than once?
1676 if (bol->is_Bool() && (max > 1 || bol->in(1)->is_SubTypeCheck())) {
1677 // Search up IDOMs to see if this IF is dominated.
1678 Node* cmp = bol->in(1);
1679 Node *cutoff = cmp->is_SubTypeCheck() ? dom_lca(get_ctrl(cmp->in(1)), get_ctrl(cmp->in(2))) : get_ctrl(bol);
1680
1681 // Now search up IDOMs till cutoff, looking for a dominating test
1682 Node *prevdom = n;
1683 Node *dom = idom(prevdom);
1684 while (dom != cutoff) {
1685 if (dom->req() > 1 && n->as_If()->same_condition(dom, &_igvn) && prevdom->in(0) == dom &&
1686 safe_for_if_replacement(dom)) {
1687 // It's invalid to move control dependent data nodes in the inner
1688 // strip-mined loop, because:
1689 // 1) break validation of LoopNode::verify_strip_mined()
1690 // 2) move code with side-effect in strip-mined loop
1691 // Move to the exit of outer strip-mined loop in that case.
1692 Node* out_le = is_inner_of_stripmined_loop(dom);
1693 if (out_le != nullptr) {
1694 prevdom = out_le;
1695 }
1696 // Replace the dominated test with an obvious true or false.
1697 // Place it on the IGVN worklist for later cleanup.
1698 C->set_major_progress();
1699 // Split if: pin array accesses that are control dependent on a range check and moved to a regular if,
1700 // to prevent an array load from floating above its range check. There are three cases:
1701 // 1. Move from RangeCheck "a" to RangeCheck "b": don't need to pin. If we ever remove b, then we pin
1702 // all its array accesses at that point.
1703 // 2. We move from RangeCheck "a" to regular if "b": need to pin. If we ever remove b, then its array
1704 // accesses would start to float, since we don't pin at that point.
1705 // 3. If we move from regular if: don't pin. All array accesses are already assumed to be pinned.
1706 bool pin_array_access_nodes = n->Opcode() == Op_RangeCheck &&
1707 prevdom->in(0)->Opcode() != Op_RangeCheck;
1708 dominated_by(prevdom->as_IfProj(), n->as_If(), false, pin_array_access_nodes);
1709 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1710 return;
1711 }
1712 prevdom = dom;
1713 dom = idom(prevdom);
1714 }
1715 }
1716 }
1717
1718 try_sink_out_of_loop(n);
1719 if (C->failing()) {
1720 return;
1721 }
1722
1723 try_move_store_after_loop(n);
1724
1725 // Remove multiple allocations of the same inline type
1726 if (n->is_InlineType()) {
1727 n->as_InlineType()->remove_redundant_allocations(this);
1728 }
1729 }
1730
1731 // Transform:
1732 //
1733 // if (some_condition) {
1734 // // body 1
1735 // } else {
1736 // // body 2
1737 // }
1738 // if (some_condition) {
1739 // // body 3
1740 // } else {
1741 // // body 4
1742 // }
1743 //
1744 // into:
1745 //
1746 //
1747 // if (some_condition) {
1748 // // body 1
1749 // // body 3
1750 // } else {
1751 // // body 2
1752 // // body 4
1753 // }
1754 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1755 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1756 Node *n_ctrl = n->in(0);
1757 IfNode* dom_if = idom(n_ctrl)->as_If();
1758 if (n->in(1) != dom_if->in(1)) {
1759 assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1760 (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1761 dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1762 _igvn.replace_input_of(n, 1, dom_if->in(1));
1763 }
1764 ProjNode* dom_proj_true = dom_if->proj_out(1);
1765 ProjNode* dom_proj_false = dom_if->proj_out(0);
1766
1767 // Now split the IF
1768 RegionNode* new_false_region;
1769 RegionNode* new_true_region;
1770 do_split_if(n, &new_false_region, &new_true_region);
1771 assert(new_false_region->req() == new_true_region->req(), "");
1772 #ifdef ASSERT
1773 for (uint i = 1; i < new_false_region->req(); ++i) {
1774 assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1775 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");
1776 }
1777 #endif
1778 assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1779
1780 // We now have:
1781 // if (some_condition) {
1782 // // body 1
1783 // if (some_condition) {
1784 // body3: // new_true_region
1785 // // body3
1786 // } else {
1787 // goto body4;
1788 // }
1789 // } else {
1790 // // body 2
1791 // if (some_condition) {
1792 // goto body3;
1793 // } else {
1794 // body4: // new_false_region
1795 // // body4;
1796 // }
1797 // }
1798 //
1799
1800 // clone pinned nodes thru the resulting regions
1801 push_pinned_nodes_thru_region(dom_if, new_true_region);
1802 push_pinned_nodes_thru_region(dom_if, new_false_region);
1803
1804 // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1805 // 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
1806 // unrelated control dependency.
1807 for (uint i = 1; i < new_false_region->req(); i++) {
1808 if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1809 dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1810 } else {
1811 assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1812 dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1813 }
1814 }
1815 return true;
1816 }
1817 return false;
1818 }
1819
1820 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1821 for (DUIterator i = region->outs(); region->has_out(i); i++) {
1822 Node* u = region->out(i);
1823 if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1824 continue;
1825 }
1826 assert(u->in(0) == region, "not a control dependent node?");
1827 uint j = 1;
1828 for (; j < u->req(); ++j) {
1829 Node* in = u->in(j);
1830 if (!is_dominator(ctrl_or_self(in), dom_if)) {
1831 break;
1832 }
1833 }
1834 if (j == u->req()) {
1835 Node *phi = PhiNode::make_blank(region, u);
1836 for (uint k = 1; k < region->req(); ++k) {
1837 Node* clone = u->clone();
1838 clone->set_req(0, region->in(k));
1839 register_new_node(clone, region->in(k));
1840 phi->init_req(k, clone);
1841 }
1842 register_new_node(phi, region);
1843 _igvn.replace_node(u, phi);
1844 --i;
1845 }
1846 }
1847 }
1848
1849 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1850 if (!dom->is_CountedLoopEnd()) {
1851 return true;
1852 }
1853 CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1854 CountedLoopNode* cl = le->loopnode();
1855 if (cl == nullptr) {
1856 return true;
1857 }
1858 if (!cl->is_main_loop()) {
1859 return true;
1860 }
1861 if (cl->is_canonical_loop_entry() == nullptr) {
1862 return true;
1863 }
1864 // Further unrolling is possible so loop exit condition might change
1865 return false;
1866 }
1867
1868 // See if a shared loop-varying computation has no loop-varying uses.
1869 // Happens if something is only used for JVM state in uncommon trap exits,
1870 // like various versions of induction variable+offset. Clone the
1871 // computation per usage to allow it to sink out of the loop.
1872 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1873 bool is_raw_to_oop_cast = n->is_ConstraintCast() &&
1874 n->in(1)->bottom_type()->isa_rawptr() &&
1875 !n->bottom_type()->isa_rawptr();
1876
1877 if (has_ctrl(n) &&
1878 !n->is_Phi() &&
1879 !n->is_Bool() &&
1880 !n->is_Proj() &&
1881 !n->is_MergeMem() &&
1882 !n->is_CMove() &&
1883 !n->is_OpaqueNotNull() &&
1884 !n->is_OpaqueInitializedAssertionPredicate() &&
1885 !n->is_OpaqueTemplateAssertionPredicate() &&
1886 !is_raw_to_oop_cast && // don't extend live ranges of raw oops
1887 (KillPathsReachableByDeadTypeNode || !n->is_Type())
1888 ) {
1889 Node *n_ctrl = get_ctrl(n);
1890 IdealLoopTree *n_loop = get_loop(n_ctrl);
1891
1892 if (n->in(0) != nullptr) {
1893 IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1894 if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1895 // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1896 // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1897 // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1898 Node* maybe_pinned_n = n;
1899 Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1900 if (!would_sink_below_pre_loop_exit(loop_ctrl, outside_ctrl)) {
1901 if (n->depends_only_on_test()) {
1902 Node* pinned_clone = n->pin_array_access_node();
1903 if (pinned_clone != nullptr) {
1904 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1905 // range check for that access. If that condition is replaced by an identical dominating one, then an
1906 // unpinned load would risk floating above its range check.
1907 register_new_node(pinned_clone, n_ctrl);
1908 maybe_pinned_n = pinned_clone;
1909 _igvn.replace_node(n, pinned_clone);
1910 }
1911 }
1912 _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1913 }
1914 }
1915 }
1916 if (n_loop != _ltree_root && n->outcnt() > 1) {
1917 // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1918 // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1919 Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1920 if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1921 ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1922 if (n->is_Store() || n->is_LoadStore()) {
1923 assert(false, "no node with a side effect");
1924 C->record_failure("no node with a side effect");
1925 return;
1926 }
1927 Node* outer_loop_clone = nullptr;
1928 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1929 Node* u = n->last_out(j); // Clone private computation per use
1930 _igvn.rehash_node_delayed(u);
1931 Node* x = nullptr;
1932 if (n->depends_only_on_test()) {
1933 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1934 // range check for that access. If that condition is replaced by an identical dominating one, then an
1935 // unpinned load would risk floating above its range check.
1936 x = n->pin_array_access_node();
1937 }
1938 if (x == nullptr) {
1939 x = n->clone();
1940 }
1941 Node* x_ctrl = nullptr;
1942 if (u->is_Phi()) {
1943 // Replace all uses of normal nodes. Replace Phi uses
1944 // individually, so the separate Nodes can sink down
1945 // different paths.
1946 uint k = 1;
1947 while (u->in(k) != n) k++;
1948 u->set_req(k, x);
1949 // x goes next to Phi input path
1950 x_ctrl = u->in(0)->in(k);
1951 // Find control for 'x' next to use but not inside inner loops.
1952 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1953 --j;
1954 } else { // Normal use
1955 if (has_ctrl(u)) {
1956 x_ctrl = get_ctrl(u);
1957 } else {
1958 x_ctrl = u->in(0);
1959 }
1960 // Find control for 'x' next to use but not inside inner loops.
1961 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1962 // Replace all uses
1963 if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1964 // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1965 // anymore now that we're going to pin n as well
1966 _igvn.replace_node(u, x);
1967 --j;
1968 } else {
1969 int nb = u->replace_edge(n, x, &_igvn);
1970 j -= nb;
1971 }
1972 }
1973
1974 if (n->is_Load()) {
1975 // For loads, add a control edge to a CFG node outside of the loop
1976 // to force them to not combine and return back inside the loop
1977 // during GVN optimization (4641526).
1978 assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1979
1980 IdealLoopTree* x_loop = get_loop(x_ctrl);
1981 Node* x_head = x_loop->_head;
1982 if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1983 // Do not add duplicate LoadNodes to the outer strip mined loop
1984 if (outer_loop_clone != nullptr) {
1985 _igvn.replace_node(x, outer_loop_clone);
1986 continue;
1987 }
1988 outer_loop_clone = x;
1989 }
1990 x->set_req(0, x_ctrl);
1991 } else if (n->in(0) != nullptr){
1992 x->set_req(0, x_ctrl);
1993 }
1994 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1995 assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1996 register_new_node(x, x_ctrl);
1997
1998 // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
1999 // All AddP nodes must keep the same base after sinking so:
2000 // 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,
2001 // their bases remain the same.
2002 // (see 2- below)
2003 assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
2004 x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
2005 !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
2006 if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
2007 !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
2008 assert(!x->is_Load(), "load should be pinned");
2009 // Use a cast node to pin clone out of loop
2010 Node* cast = nullptr;
2011 for (uint k = 0; k < x->req(); k++) {
2012 Node* in = x->in(k);
2013 if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
2014 const Type* in_t = _igvn.type(in);
2015 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
2016 ConstraintCastNode::UnconditionalDependency, nullptr);
2017 }
2018 if (cast != nullptr) {
2019 Node* prev = _igvn.hash_find_insert(cast);
2020 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
2021 cast->destruct(&_igvn);
2022 cast = prev;
2023 } else {
2024 register_new_node(cast, x_ctrl);
2025 }
2026 x->replace_edge(in, cast);
2027 // Chain of AddP nodes:
2028 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
2029 if (x->is_AddP() && k == AddPNode::Base) {
2030 update_addp_chain_base(x, n->in(AddPNode::Base), cast);
2031 }
2032 break;
2033 }
2034 }
2035 assert(cast != nullptr, "must have added a cast to pin the node");
2036 }
2037 }
2038 _igvn.remove_dead_node(n);
2039 }
2040 _dom_lca_tags_round = 0;
2041 }
2042 }
2043 }
2044
2045 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
2046 ResourceMark rm;
2047 Node_List wq;
2048 wq.push(x);
2049 while (wq.size() != 0) {
2050 Node* n = wq.pop();
2051 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2052 Node* u = n->fast_out(i);
2053 if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
2054 _igvn.replace_input_of(u, AddPNode::Base, new_base);
2055 wq.push(u);
2056 }
2057 }
2058 }
2059 }
2060
2061 // Compute the early control of a node by following its inputs until we reach
2062 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
2063 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
2064 Node* early_ctrl = nullptr;
2065 ResourceMark rm;
2066 Unique_Node_List wq;
2067 wq.push(n);
2068 for (uint i = 0; i < wq.size(); i++) {
2069 Node* m = wq.at(i);
2070 Node* c = nullptr;
2071 if (m->is_CFG()) {
2072 c = m;
2073 } else if (m->pinned()) {
2074 c = m->in(0);
2075 } else {
2076 for (uint j = 0; j < m->req(); j++) {
2077 Node* in = m->in(j);
2078 if (in != nullptr) {
2079 wq.push(in);
2080 }
2081 }
2082 }
2083 if (c != nullptr) {
2084 assert(is_dominator(c, n_ctrl), "control input must dominate current control");
2085 if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
2086 early_ctrl = c;
2087 }
2088 }
2089 }
2090 assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
2091 return early_ctrl;
2092 }
2093
2094 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
2095 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2096 Node* u = n->fast_out(i);
2097 if (u->is_Opaque1()) {
2098 return false; // Found loop limit, bugfix for 4677003
2099 }
2100 // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
2101 // get_late_ctrl_with_anti_dep() use their own tag
2102 _dom_lca_tags_round++;
2103 assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
2104
2105 if (u->is_Phi()) {
2106 for (uint j = 1; j < u->req(); ++j) {
2107 if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
2108 return false;
2109 }
2110 }
2111 } else {
2112 Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
2113 if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
2114 return false;
2115 }
2116 }
2117 }
2118 return true;
2119 }
2120
2121 // 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
2122 // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
2123 // 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
2124 // it would be to not eliminate the check in the main loop. Instead, we prevent sinking of the node here so better code
2125 // is generated for the main loop.
2126 bool PhaseIdealLoop::would_sink_below_pre_loop_exit(IdealLoopTree* n_loop, Node* ctrl) {
2127 if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
2128 CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
2129 if (is_dominator(pre_loop->loopexit(), ctrl)) {
2130 return true;
2131 }
2132 }
2133 return false;
2134 }
2135
2136 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
2137 if (n->is_Load()) {
2138 ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
2139 }
2140 IdealLoopTree *u_loop = get_loop(ctrl);
2141 if (u_loop == n_loop) {
2142 return false; // Found loop-varying use
2143 }
2144 if (n_loop->is_member(u_loop)) {
2145 return false; // Found use in inner loop
2146 }
2147 if (would_sink_below_pre_loop_exit(n_loop, ctrl)) {
2148 return false;
2149 }
2150 return true;
2151 }
2152
2153 //------------------------------split_if_with_blocks---------------------------
2154 // Check for aggressive application of 'split-if' optimization,
2155 // using basic block level info.
2156 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
2157 Node* root = C->root();
2158 visited.set(root->_idx); // first, mark root as visited
2159 // Do pre-visit work for root
2160 Node* n = split_if_with_blocks_pre(root);
2161 uint cnt = n->outcnt();
2162 uint i = 0;
2163
2164 while (true) {
2165 // Visit all children
2166 if (i < cnt) {
2167 Node* use = n->raw_out(i);
2168 ++i;
2169 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
2170 // Now do pre-visit work for this use
2171 use = split_if_with_blocks_pre(use);
2172 nstack.push(n, i); // Save parent and next use's index.
2173 n = use; // Process all children of current use.
2174 cnt = use->outcnt();
2175 i = 0;
2176 }
2177 }
2178 else {
2179 // All of n's children have been processed, complete post-processing.
2180 if (cnt != 0 && !n->is_Con()) {
2181 assert(has_node(n), "no dead nodes");
2182 split_if_with_blocks_post(n);
2183 if (C->failing()) {
2184 return;
2185 }
2186 }
2187 if (must_throttle_split_if()) {
2188 nstack.clear();
2189 }
2190 if (nstack.is_empty()) {
2191 // Finished all nodes on stack.
2192 break;
2193 }
2194 // Get saved parent node and next use's index. Visit the rest of uses.
2195 n = nstack.node();
2196 cnt = n->outcnt();
2197 i = nstack.index();
2198 nstack.pop();
2199 }
2200 }
2201 }
2202
2203
2204 //=============================================================================
2205 //
2206 // C L O N E A L O O P B O D Y
2207 //
2208
2209 //------------------------------clone_iff--------------------------------------
2210 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2211 // "Nearly" because all Nodes have been cloned from the original in the loop,
2212 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2213 // through the Phi recursively, and return a Bool.
2214 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2215
2216 // Convert this Phi into a Phi merging Bools
2217 uint i;
2218 for (i = 1; i < phi->req(); i++) {
2219 Node* b = phi->in(i);
2220 if (b->is_Phi()) {
2221 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2222 } else {
2223 assert(b->is_Bool() || b->is_OpaqueNotNull() || b->is_OpaqueInitializedAssertionPredicate(),
2224 "bool, non-null check with OpaqueNotNull or Initialized Assertion Predicate with its Opaque node");
2225 }
2226 }
2227 Node* n = phi->in(1);
2228 Node* sample_opaque = nullptr;
2229 Node *sample_bool = nullptr;
2230 if (n->is_OpaqueNotNull() || n->is_OpaqueInitializedAssertionPredicate()) {
2231 sample_opaque = n;
2232 sample_bool = n->in(1);
2233 assert(sample_bool->is_Bool(), "wrong type");
2234 } else {
2235 sample_bool = n;
2236 }
2237 Node* sample_cmp = sample_bool->in(1);
2238 const Type* t = Type::TOP;
2239 const TypePtr* at = nullptr;
2240 if (sample_cmp->is_FlatArrayCheck()) {
2241 // Left input of a FlatArrayCheckNode is memory, set the (adr) type of the phi accordingly
2242 assert(sample_cmp->in(1)->bottom_type() == Type::MEMORY, "unexpected input type");
2243 t = Type::MEMORY;
2244 at = TypeRawPtr::BOTTOM;
2245 }
2246
2247 // Make Phis to merge the Cmp's inputs.
2248 PhiNode *phi1 = new PhiNode(phi->in(0), t, at);
2249 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2250 for (i = 1; i < phi->req(); i++) {
2251 Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2252 Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2253 phi1->set_req(i, n1);
2254 phi2->set_req(i, n2);
2255 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2256 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2257 }
2258 // See if these Phis have been made before.
2259 // Register with optimizer
2260 Node *hit1 = _igvn.hash_find_insert(phi1);
2261 if (hit1) { // Hit, toss just made Phi
2262 _igvn.remove_dead_node(phi1); // Remove new phi
2263 assert(hit1->is_Phi(), "" );
2264 phi1 = (PhiNode*)hit1; // Use existing phi
2265 } else { // Miss
2266 _igvn.register_new_node_with_optimizer(phi1);
2267 }
2268 Node *hit2 = _igvn.hash_find_insert(phi2);
2269 if (hit2) { // Hit, toss just made Phi
2270 _igvn.remove_dead_node(phi2); // Remove new phi
2271 assert(hit2->is_Phi(), "" );
2272 phi2 = (PhiNode*)hit2; // Use existing phi
2273 } else { // Miss
2274 _igvn.register_new_node_with_optimizer(phi2);
2275 }
2276 // Register Phis with loop/block info
2277 set_ctrl(phi1, phi->in(0));
2278 set_ctrl(phi2, phi->in(0));
2279 // Make a new Cmp
2280 Node *cmp = sample_cmp->clone();
2281 cmp->set_req(1, phi1);
2282 cmp->set_req(2, phi2);
2283 _igvn.register_new_node_with_optimizer(cmp);
2284 set_ctrl(cmp, phi->in(0));
2285
2286 // Make a new Bool
2287 Node *b = sample_bool->clone();
2288 b->set_req(1,cmp);
2289 _igvn.register_new_node_with_optimizer(b);
2290 set_ctrl(b, phi->in(0));
2291
2292 if (sample_opaque != nullptr) {
2293 Node* opaque = sample_opaque->clone();
2294 opaque->set_req(1, b);
2295 _igvn.register_new_node_with_optimizer(opaque);
2296 set_ctrl(opaque, phi->in(0));
2297 return opaque;
2298 }
2299
2300 assert(b->is_Bool(), "");
2301 return b;
2302 }
2303
2304 //------------------------------clone_bool-------------------------------------
2305 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2306 // "Nearly" because all Nodes have been cloned from the original in the loop,
2307 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2308 // through the Phi recursively, and return a Bool.
2309 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2310 uint i;
2311 // Convert this Phi into a Phi merging Bools
2312 for( i = 1; i < phi->req(); i++ ) {
2313 Node *b = phi->in(i);
2314 if( b->is_Phi() ) {
2315 _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2316 } else {
2317 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2318 }
2319 }
2320
2321 Node *sample_cmp = phi->in(1);
2322
2323 // Make Phis to merge the Cmp's inputs.
2324 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2325 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2326 for( uint j = 1; j < phi->req(); j++ ) {
2327 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2328 Node *n1, *n2;
2329 if( cmp_top->is_Cmp() ) {
2330 n1 = cmp_top->in(1);
2331 n2 = cmp_top->in(2);
2332 } else {
2333 n1 = n2 = cmp_top;
2334 }
2335 phi1->set_req( j, n1 );
2336 phi2->set_req( j, n2 );
2337 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2338 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2339 }
2340
2341 // See if these Phis have been made before.
2342 // Register with optimizer
2343 Node *hit1 = _igvn.hash_find_insert(phi1);
2344 if( hit1 ) { // Hit, toss just made Phi
2345 _igvn.remove_dead_node(phi1); // Remove new phi
2346 assert( hit1->is_Phi(), "" );
2347 phi1 = (PhiNode*)hit1; // Use existing phi
2348 } else { // Miss
2349 _igvn.register_new_node_with_optimizer(phi1);
2350 }
2351 Node *hit2 = _igvn.hash_find_insert(phi2);
2352 if( hit2 ) { // Hit, toss just made Phi
2353 _igvn.remove_dead_node(phi2); // Remove new phi
2354 assert( hit2->is_Phi(), "" );
2355 phi2 = (PhiNode*)hit2; // Use existing phi
2356 } else { // Miss
2357 _igvn.register_new_node_with_optimizer(phi2);
2358 }
2359 // Register Phis with loop/block info
2360 set_ctrl(phi1, phi->in(0));
2361 set_ctrl(phi2, phi->in(0));
2362 // Make a new Cmp
2363 Node *cmp = sample_cmp->clone();
2364 cmp->set_req( 1, phi1 );
2365 cmp->set_req( 2, phi2 );
2366 _igvn.register_new_node_with_optimizer(cmp);
2367 set_ctrl(cmp, phi->in(0));
2368
2369 assert( cmp->is_Cmp(), "" );
2370 return (CmpNode*)cmp;
2371 }
2372
2373 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2374 IdealLoopTree* loop, IdealLoopTree* outer_loop,
2375 Node_List*& split_if_set, Node_List*& split_bool_set,
2376 Node_List*& split_cex_set, Node_List& worklist,
2377 uint new_counter, CloneLoopMode mode) {
2378 Node* nnn = old_new[old->_idx];
2379 // Copy uses to a worklist, so I can munge the def-use info
2380 // with impunity.
2381 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2382 worklist.push(old->fast_out(j));
2383
2384 while( worklist.size() ) {
2385 Node *use = worklist.pop();
2386 if (!has_node(use)) continue; // Ignore dead nodes
2387 if (use->in(0) == C->top()) continue;
2388 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2389 // Check for data-use outside of loop - at least one of OLD or USE
2390 // must not be a CFG node.
2391 #ifdef ASSERT
2392 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2393 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2394 assert(mode != IgnoreStripMined, "incorrect cloning mode");
2395 assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2396 }
2397 #endif
2398 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2399
2400 // If the Data use is an IF, that means we have an IF outside the
2401 // loop that is switching on a condition that is set inside the
2402 // loop. Happens if people set a loop-exit flag; then test the flag
2403 // in the loop to break the loop, then test is again outside the
2404 // loop to determine which way the loop exited.
2405 //
2406 // For several uses we need to make sure that there is no phi between,
2407 // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2408 // to avoid such a phi in between.
2409 // For example, it is unexpected that there is a Phi between an
2410 // AllocateArray node and its ValidLengthTest input that could cause
2411 // split if to break.
2412 assert(!use->is_OpaqueTemplateAssertionPredicate(),
2413 "should not clone a Template Assertion Predicate which should be removed once it's useless");
2414 if (use->is_If() || use->is_CMove() || use->is_OpaqueNotNull() || use->is_OpaqueInitializedAssertionPredicate() ||
2415 (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2416 // Since this code is highly unlikely, we lazily build the worklist
2417 // of such Nodes to go split.
2418 if (!split_if_set) {
2419 split_if_set = new Node_List();
2420 }
2421 split_if_set->push(use);
2422 }
2423 if (use->is_Bool()) {
2424 if (!split_bool_set) {
2425 split_bool_set = new Node_List();
2426 }
2427 split_bool_set->push(use);
2428 }
2429 if (use->Opcode() == Op_CreateEx) {
2430 if (!split_cex_set) {
2431 split_cex_set = new Node_List();
2432 }
2433 split_cex_set->push(use);
2434 }
2435
2436
2437 // Get "block" use is in
2438 uint idx = 0;
2439 while( use->in(idx) != old ) idx++;
2440 Node *prev = use->is_CFG() ? use : get_ctrl(use);
2441 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2442 Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2443 ? prev->in(2)
2444 : idom(prev);
2445 if( use->is_Phi() ) // Phi use is in prior block
2446 cfg = prev->in(idx); // NOT in block of Phi itself
2447 if (cfg->is_top()) { // Use is dead?
2448 _igvn.replace_input_of(use, idx, C->top());
2449 continue;
2450 }
2451
2452 // If use is referenced through control edge... (idx == 0)
2453 if (mode == IgnoreStripMined && idx == 0) {
2454 LoopNode *head = loop->_head->as_Loop();
2455 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2456 // That node is outside the inner loop, leave it outside the
2457 // outer loop as well to not confuse verification code.
2458 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2459 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2460 continue;
2461 }
2462 }
2463
2464 while(!outer_loop->is_member(get_loop(cfg))) {
2465 prev = cfg;
2466 cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2467 }
2468 // If the use occurs after merging several exits from the loop, then
2469 // old value must have dominated all those exits. Since the same old
2470 // value was used on all those exits we did not need a Phi at this
2471 // merge point. NOW we do need a Phi here. Each loop exit value
2472 // is now merged with the peeled body exit; each exit gets its own
2473 // private Phi and those Phis need to be merged here.
2474 Node *phi;
2475 if( prev->is_Region() ) {
2476 if( idx == 0 ) { // Updating control edge?
2477 phi = prev; // Just use existing control
2478 } else { // Else need a new Phi
2479 phi = PhiNode::make( prev, old );
2480 // Now recursively fix up the new uses of old!
2481 for( uint i = 1; i < prev->req(); i++ ) {
2482 worklist.push(phi); // Onto worklist once for each 'old' input
2483 }
2484 }
2485 } else {
2486 // Get new RegionNode merging old and new loop exits
2487 prev = old_new[prev->_idx];
2488 assert( prev, "just made this in step 7" );
2489 if( idx == 0) { // Updating control edge?
2490 phi = prev; // Just use existing control
2491 } else { // Else need a new Phi
2492 // Make a new Phi merging data values properly
2493 phi = PhiNode::make( prev, old );
2494 phi->set_req( 1, nnn );
2495 }
2496 }
2497 // If inserting a new Phi, check for prior hits
2498 if( idx != 0 ) {
2499 Node *hit = _igvn.hash_find_insert(phi);
2500 if( hit == nullptr ) {
2501 _igvn.register_new_node_with_optimizer(phi); // Register new phi
2502 } else { // or
2503 // Remove the new phi from the graph and use the hit
2504 _igvn.remove_dead_node(phi);
2505 phi = hit; // Use existing phi
2506 }
2507 set_ctrl(phi, prev);
2508 }
2509 // Make 'use' use the Phi instead of the old loop body exit value
2510 assert(use->in(idx) == old, "old is still input of use");
2511 // We notify all uses of old, including use, and the indirect uses,
2512 // that may now be optimized because we have replaced old with phi.
2513 _igvn.add_users_to_worklist(old);
2514 if (idx == 0 &&
2515 use->depends_only_on_test()) {
2516 Node* pinned_clone = use->pin_array_access_node();
2517 if (pinned_clone != nullptr) {
2518 // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path
2519 // into the region is left, an array load could become dependent on a condition that's not a range check for
2520 // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
2521 // floating above its range check.
2522 pinned_clone->set_req(0, phi);
2523 register_new_node_with_ctrl_of(pinned_clone, use);
2524 _igvn.replace_node(use, pinned_clone);
2525 continue;
2526 }
2527 }
2528 _igvn.replace_input_of(use, idx, phi);
2529 if( use->_idx >= new_counter ) { // If updating new phis
2530 // Not needed for correctness, but prevents a weak assert
2531 // in AddPNode from tripping (when we end up with different
2532 // base & derived Phis that will become the same after
2533 // IGVN does CSE).
2534 Node *hit = _igvn.hash_find_insert(use);
2535 if( hit ) // Go ahead and re-hash for hits.
2536 _igvn.replace_node( use, hit );
2537 }
2538 }
2539 }
2540 }
2541
2542 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2543 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2544 bool check_old_new) {
2545 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2546 Node* u = n->fast_out(j);
2547 assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2548 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2549 Node* c = phase->get_ctrl(u);
2550 IdealLoopTree* u_loop = phase->get_loop(c);
2551 assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2552 if (!loop->is_member(u_loop)) {
2553 if (outer_loop->is_member(u_loop)) {
2554 wq.push(u);
2555 } else {
2556 // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2557 // the outer loop too
2558 Node* u_c = u->in(0);
2559 if (u_c != nullptr) {
2560 IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2561 if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2562 wq.push(u);
2563 }
2564 }
2565 }
2566 }
2567 }
2568 }
2569 }
2570
2571 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2572 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2573 Node_List& extra_data_nodes) {
2574 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2575 CountedLoopNode* cl = head->as_CountedLoop();
2576 Node* l = cl->outer_loop();
2577 Node* tail = cl->outer_loop_tail();
2578 IfNode* le = cl->outer_loop_end();
2579 Node* sfpt = cl->outer_safepoint();
2580 CountedLoopEndNode* cle = cl->loopexit();
2581 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2582 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2583 Node* cle_out = cle->proj_out(false);
2584
2585 Node* new_sfpt = nullptr;
2586 Node* new_cle_out = cle_out->clone();
2587 old_new.map(cle_out->_idx, new_cle_out);
2588 if (mode == CloneIncludesStripMined) {
2589 // clone outer loop body
2590 Node* new_l = l->clone();
2591 Node* new_tail = tail->clone();
2592 IfNode* new_le = le->clone()->as_If();
2593 new_sfpt = sfpt->clone();
2594
2595 set_loop(new_l, outer_loop->_parent);
2596 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2597 set_loop(new_cle_out, outer_loop->_parent);
2598 set_idom(new_cle_out, new_cle, dd);
2599 set_loop(new_sfpt, outer_loop->_parent);
2600 set_idom(new_sfpt, new_cle_out, dd);
2601 set_loop(new_le, outer_loop->_parent);
2602 set_idom(new_le, new_sfpt, dd);
2603 set_loop(new_tail, outer_loop->_parent);
2604 set_idom(new_tail, new_le, dd);
2605 set_idom(new_cl, new_l, dd);
2606
2607 old_new.map(l->_idx, new_l);
2608 old_new.map(tail->_idx, new_tail);
2609 old_new.map(le->_idx, new_le);
2610 old_new.map(sfpt->_idx, new_sfpt);
2611
2612 new_l->set_req(LoopNode::LoopBackControl, new_tail);
2613 new_l->set_req(0, new_l);
2614 new_tail->set_req(0, new_le);
2615 new_le->set_req(0, new_sfpt);
2616 new_sfpt->set_req(0, new_cle_out);
2617 new_cle_out->set_req(0, new_cle);
2618 new_cl->set_req(LoopNode::EntryControl, new_l);
2619
2620 _igvn.register_new_node_with_optimizer(new_l);
2621 _igvn.register_new_node_with_optimizer(new_tail);
2622 _igvn.register_new_node_with_optimizer(new_le);
2623 } else {
2624 Node *newhead = old_new[loop->_head->_idx];
2625 newhead->as_Loop()->clear_strip_mined();
2626 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2627 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2628 }
2629 // Look at data node that were assigned a control in the outer
2630 // loop: they are kept in the outer loop by the safepoint so start
2631 // from the safepoint node's inputs.
2632 IdealLoopTree* outer_loop = get_loop(l);
2633 Node_Stack stack(2);
2634 stack.push(sfpt, 1);
2635 uint new_counter = C->unique();
2636 while (stack.size() > 0) {
2637 Node* n = stack.node();
2638 uint i = stack.index();
2639 while (i < n->req() &&
2640 (n->in(i) == nullptr ||
2641 !has_ctrl(n->in(i)) ||
2642 get_loop(get_ctrl(n->in(i))) != outer_loop ||
2643 (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2644 i++;
2645 }
2646 if (i < n->req()) {
2647 stack.set_index(i+1);
2648 stack.push(n->in(i), 0);
2649 } else {
2650 assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2651 Node* m = n == sfpt ? new_sfpt : n->clone();
2652 if (m != nullptr) {
2653 for (uint i = 0; i < n->req(); i++) {
2654 if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2655 m->set_req(i, old_new[m->in(i)->_idx]);
2656 }
2657 }
2658 } else {
2659 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2660 }
2661 if (n != sfpt) {
2662 extra_data_nodes.push(n);
2663 _igvn.register_new_node_with_optimizer(m);
2664 assert(get_ctrl(n) == cle_out, "what other control?");
2665 set_ctrl(m, new_cle_out);
2666 old_new.map(n->_idx, m);
2667 }
2668 stack.pop();
2669 }
2670 }
2671 if (mode == CloneIncludesStripMined) {
2672 _igvn.register_new_node_with_optimizer(new_sfpt);
2673 _igvn.register_new_node_with_optimizer(new_cle_out);
2674 }
2675 // Some other transformation may have pessimistically assigned some
2676 // data nodes to the outer loop. Set their control so they are out
2677 // of the outer loop.
2678 ResourceMark rm;
2679 Unique_Node_List wq;
2680 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2681 Node* old = extra_data_nodes.at(i);
2682 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2683 }
2684
2685 for (uint i = 0; i < loop->_body.size(); i++) {
2686 Node* old = loop->_body.at(i);
2687 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2688 }
2689
2690 Node* inner_out = sfpt->in(0);
2691 if (inner_out->outcnt() > 1) {
2692 collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2693 }
2694
2695 Node* new_ctrl = cl->outer_loop_exit();
2696 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2697 for (uint i = 0; i < wq.size(); i++) {
2698 Node* n = wq.at(i);
2699 set_ctrl(n, new_ctrl);
2700 if (n->in(0) != nullptr) {
2701 _igvn.replace_input_of(n, 0, new_ctrl);
2702 }
2703 collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2704 }
2705 } else {
2706 Node *newhead = old_new[loop->_head->_idx];
2707 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2708 }
2709 }
2710
2711 //------------------------------clone_loop-------------------------------------
2712 //
2713 // C L O N E A L O O P B O D Y
2714 //
2715 // This is the basic building block of the loop optimizations. It clones an
2716 // entire loop body. It makes an old_new loop body mapping; with this mapping
2717 // you can find the new-loop equivalent to an old-loop node. All new-loop
2718 // nodes are exactly equal to their old-loop counterparts, all edges are the
2719 // same. All exits from the old-loop now have a RegionNode that merges the
2720 // equivalent new-loop path. This is true even for the normal "loop-exit"
2721 // condition. All uses of loop-invariant old-loop values now come from (one
2722 // or more) Phis that merge their new-loop equivalents.
2723 //
2724 // This operation leaves the graph in an illegal state: there are two valid
2725 // control edges coming from the loop pre-header to both loop bodies. I'll
2726 // definitely have to hack the graph after running this transform.
2727 //
2728 // From this building block I will further edit edges to perform loop peeling
2729 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2730 //
2731 // Parameter side_by_size_idom:
2732 // When side_by_size_idom is null, the dominator tree is constructed for
2733 // the clone loop to dominate the original. Used in construction of
2734 // pre-main-post loop sequence.
2735 // When nonnull, the clone and original are side-by-side, both are
2736 // dominated by the side_by_side_idom node. Used in construction of
2737 // unswitched loops.
2738 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2739 CloneLoopMode mode, Node* side_by_side_idom) {
2740
2741 LoopNode* head = loop->_head->as_Loop();
2742 head->verify_strip_mined(1);
2743
2744 if (C->do_vector_loop() && PrintOpto) {
2745 const char* mname = C->method()->name()->as_quoted_ascii();
2746 if (mname != nullptr) {
2747 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2748 }
2749 }
2750
2751 CloneMap& cm = C->clone_map();
2752 if (C->do_vector_loop()) {
2753 cm.set_clone_idx(cm.max_gen()+1);
2754 #ifndef PRODUCT
2755 if (PrintOpto) {
2756 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2757 loop->dump_head();
2758 }
2759 #endif
2760 }
2761
2762 // Step 1: Clone the loop body. Make the old->new mapping.
2763 clone_loop_body(loop->_body, old_new, &cm);
2764
2765 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2766
2767 // Step 2: Fix the edges in the new body. If the old input is outside the
2768 // loop use it. If the old input is INside the loop, use the corresponding
2769 // new node instead.
2770 fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2771
2772 Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2773 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2774
2775 // Step 3: Now fix control uses. Loop varying control uses have already
2776 // been fixed up (as part of all input edges in Step 2). Loop invariant
2777 // control uses must be either an IfFalse or an IfTrue. Make a merge
2778 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2779 // refer to this.
2780 Node_List worklist;
2781 uint new_counter = C->unique();
2782 fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2783
2784 // Step 4: If loop-invariant use is not control, it must be dominated by a
2785 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2786 // there if needed. Make a Phi there merging old and new used values.
2787 Node_List *split_if_set = nullptr;
2788 Node_List *split_bool_set = nullptr;
2789 Node_List *split_cex_set = nullptr;
2790 fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2791
2792 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2793 Node* old = extra_data_nodes.at(i);
2794 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2795 split_bool_set, split_cex_set, worklist, new_counter,
2796 mode);
2797 }
2798
2799 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2800 // the loop uses a condition set in the loop. The original IF probably
2801 // takes control from one or more OLD Regions (which in turn get from NEW
2802 // Regions). In any case, there will be a set of Phis for each merge point
2803 // from the IF up to where the original BOOL def exists the loop.
2804 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2805
2806 }
2807
2808 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2809 if (split_if_set) {
2810 while (split_if_set->size()) {
2811 Node *iff = split_if_set->pop();
2812 uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2813 if (iff->in(input)->is_Phi()) {
2814 Node *b = clone_iff(iff->in(input)->as_Phi());
2815 _igvn.replace_input_of(iff, input, b);
2816 }
2817 }
2818 }
2819 if (split_bool_set) {
2820 while (split_bool_set->size()) {
2821 Node *b = split_bool_set->pop();
2822 Node *phi = b->in(1);
2823 assert(phi->is_Phi(), "");
2824 CmpNode *cmp = clone_bool((PhiNode*) phi);
2825 _igvn.replace_input_of(b, 1, cmp);
2826 }
2827 }
2828 if (split_cex_set) {
2829 while (split_cex_set->size()) {
2830 Node *b = split_cex_set->pop();
2831 assert(b->in(0)->is_Region(), "");
2832 assert(b->in(1)->is_Phi(), "");
2833 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2834 split_up(b, b->in(0), nullptr);
2835 }
2836 }
2837 }
2838
2839 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2840 uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2841 Node_List*& split_bool_set, Node_List*& split_cex_set) {
2842 for(uint i = 0; i < body.size(); i++ ) {
2843 Node* old = body.at(i);
2844 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2845 split_bool_set, split_cex_set, worklist, new_counter,
2846 mode);
2847 }
2848 }
2849
2850 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2851 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2852 LoopNode* head = loop->_head->as_Loop();
2853 for(uint i = 0; i < body.size(); i++ ) {
2854 Node* old = body.at(i);
2855 if( !old->is_CFG() ) continue;
2856
2857 // Copy uses to a worklist, so I can munge the def-use info
2858 // with impunity.
2859 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2860 worklist.push(old->fast_out(j));
2861 }
2862
2863 while (worklist.size()) { // Visit all uses
2864 Node *use = worklist.pop();
2865 if (!has_node(use)) continue; // Ignore dead nodes
2866 IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2867 if (!loop->is_member(use_loop) && use->is_CFG()) {
2868 // Both OLD and USE are CFG nodes here.
2869 assert(use->is_Proj(), "" );
2870 Node* nnn = old_new[old->_idx];
2871
2872 Node* newuse = nullptr;
2873 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2874 CountedLoopNode* cl = head->as_CountedLoop();
2875 CountedLoopEndNode* cle = cl->loopexit();
2876 // is use the projection that exits the loop from the CountedLoopEndNode?
2877 if (use->in(0) == cle) {
2878 IfFalseNode* cle_out = use->as_IfFalse();
2879 IfNode* le = cl->outer_loop_end();
2880 use = le->proj_out(false);
2881 use_loop = get_loop(use);
2882 if (mode == CloneIncludesStripMined) {
2883 nnn = old_new[le->_idx];
2884 } else {
2885 newuse = old_new[cle_out->_idx];
2886 }
2887 }
2888 }
2889 if (newuse == nullptr) {
2890 newuse = use->clone();
2891 }
2892
2893 // Clone the loop exit control projection
2894 if (C->do_vector_loop() && cm != nullptr) {
2895 cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2896 }
2897 newuse->set_req(0,nnn);
2898 _igvn.register_new_node_with_optimizer(newuse);
2899 set_loop(newuse, use_loop);
2900 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2901
2902 // We need a Region to merge the exit from the peeled body and the
2903 // exit from the old loop body.
2904 RegionNode *r = new RegionNode(3);
2905 uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2906 assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2907
2908 // The original user of 'use' uses 'r' instead.
2909 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2910 Node* useuse = use->last_out(l);
2911 _igvn.rehash_node_delayed(useuse);
2912 uint uses_found = 0;
2913 if (useuse->in(0) == use) {
2914 useuse->set_req(0, r);
2915 uses_found++;
2916 if (useuse->is_CFG()) {
2917 // This is not a dom_depth > dd_r because when new
2918 // control flow is constructed by a loop opt, a node and
2919 // its dominator can end up at the same dom_depth
2920 assert(dom_depth(useuse) >= dd_r, "");
2921 set_idom(useuse, r, dom_depth(useuse));
2922 }
2923 }
2924 for (uint k = 1; k < useuse->req(); k++) {
2925 if( useuse->in(k) == use ) {
2926 useuse->set_req(k, r);
2927 uses_found++;
2928 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2929 // This is not a dom_depth > dd_r because when new
2930 // control flow is constructed by a loop opt, a node
2931 // and its dominator can end up at the same dom_depth
2932 assert(dom_depth(useuse) >= dd_r , "");
2933 set_idom(useuse, r, dom_depth(useuse));
2934 }
2935 }
2936 }
2937 l -= uses_found; // we deleted 1 or more copies of this edge
2938 }
2939
2940 assert(use->is_Proj(), "loop exit should be projection");
2941 // replace_node_and_forward_ctrl() below moves all nodes that are:
2942 // - control dependent on the loop exit or
2943 // - have control set to the loop exit
2944 // below the post-loop merge point.
2945 // replace_node_and_forward_ctrl() takes a dead control as first input.
2946 // To make it possible to use it, the loop exit projection is cloned and becomes the
2947 // new exit projection. The initial one becomes dead and is "replaced" by the region.
2948 Node* use_clone = use->clone();
2949 register_control(use_clone, use_loop, idom(use), dom_depth(use));
2950 // Now finish up 'r'
2951 r->set_req(1, newuse);
2952 r->set_req(2, use_clone);
2953 _igvn.register_new_node_with_optimizer(r);
2954 set_loop(r, use_loop);
2955 set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2956 replace_node_and_forward_ctrl(use, r);
2957 // Map the (cloned) old use to the new merge point
2958 old_new.map(use_clone->_idx, r);
2959 } // End of if a loop-exit test
2960 }
2961 }
2962 }
2963
2964 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2965 IdealLoopTree* parent, bool partial) {
2966 for(uint i = 0; i < body.size(); i++ ) {
2967 Node *old = body.at(i);
2968 Node *nnn = old_new[old->_idx];
2969 // Fix CFG/Loop controlling the new node
2970 if (has_ctrl(old)) {
2971 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2972 } else {
2973 set_loop(nnn, parent);
2974 if (old->outcnt() > 0) {
2975 Node* dom = idom(old);
2976 if (old_new[dom->_idx] != nullptr) {
2977 dom = old_new[dom->_idx];
2978 set_idom(nnn, dom, dd );
2979 }
2980 }
2981 }
2982 // Correct edges to the new node
2983 for (uint j = 0; j < nnn->req(); j++) {
2984 Node *n = nnn->in(j);
2985 if (n != nullptr) {
2986 IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2987 if (loop->is_member(old_in_loop)) {
2988 if (old_new[n->_idx] != nullptr) {
2989 nnn->set_req(j, old_new[n->_idx]);
2990 } else {
2991 assert(!body.contains(n), "");
2992 assert(partial, "node not cloned");
2993 }
2994 }
2995 }
2996 }
2997 _igvn.hash_find_insert(nnn);
2998 }
2999 }
3000
3001 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
3002 for (uint i = 0; i < body.size(); i++) {
3003 Node* old = body.at(i);
3004 Node* nnn = old->clone();
3005 old_new.map(old->_idx, nnn);
3006 if (C->do_vector_loop() && cm != nullptr) {
3007 cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
3008 }
3009 _igvn.register_new_node_with_optimizer(nnn);
3010 }
3011 }
3012
3013
3014 //---------------------- stride_of_possible_iv -------------------------------------
3015 // Looks for an iff/bool/comp with one operand of the compare
3016 // being a cycle involving an add and a phi,
3017 // with an optional truncation (left-shift followed by a right-shift)
3018 // of the add. Returns zero if not an iv.
3019 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
3020 Node* trunc1 = nullptr;
3021 Node* trunc2 = nullptr;
3022 const TypeInteger* ttype = nullptr;
3023 if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
3024 return 0;
3025 }
3026 BoolNode* bl = iff->in(1)->as_Bool();
3027 Node* cmp = bl->in(1);
3028 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
3029 return 0;
3030 }
3031 // Must have an invariant operand
3032 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
3033 return 0;
3034 }
3035 Node* add2 = nullptr;
3036 Node* cmp1 = cmp->in(1);
3037 if (cmp1->is_Phi()) {
3038 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
3039 Node* phi = cmp1;
3040 for (uint i = 1; i < phi->req(); i++) {
3041 Node* in = phi->in(i);
3042 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
3043 &trunc1, &trunc2, &ttype, T_INT);
3044 if (add && add->in(1) == phi) {
3045 add2 = add->in(2);
3046 break;
3047 }
3048 }
3049 } else {
3050 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
3051 Node* addtrunc = cmp1;
3052 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
3053 &trunc1, &trunc2, &ttype, T_INT);
3054 if (add && add->in(1)->is_Phi()) {
3055 Node* phi = add->in(1);
3056 for (uint i = 1; i < phi->req(); i++) {
3057 if (phi->in(i) == addtrunc) {
3058 add2 = add->in(2);
3059 break;
3060 }
3061 }
3062 }
3063 }
3064 if (add2 != nullptr) {
3065 const TypeInt* add2t = _igvn.type(add2)->is_int();
3066 if (add2t->is_con()) {
3067 return add2t->get_con();
3068 }
3069 }
3070 return 0;
3071 }
3072
3073
3074 //---------------------- stay_in_loop -------------------------------------
3075 // Return the (unique) control output node that's in the loop (if it exists.)
3076 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
3077 Node* unique = nullptr;
3078 if (!n) return nullptr;
3079 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3080 Node* use = n->fast_out(i);
3081 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
3082 if (unique != nullptr) {
3083 return nullptr;
3084 }
3085 unique = use;
3086 }
3087 }
3088 return unique;
3089 }
3090
3091 //------------------------------ register_node -------------------------------------
3092 // Utility to register node "n" with PhaseIdealLoop
3093 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
3094 _igvn.register_new_node_with_optimizer(n);
3095 loop->_body.push(n);
3096 if (n->is_CFG()) {
3097 set_loop(n, loop);
3098 set_idom(n, pred, ddepth);
3099 } else {
3100 set_ctrl(n, pred);
3101 }
3102 }
3103
3104 //------------------------------ proj_clone -------------------------------------
3105 // Utility to create an if-projection
3106 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
3107 ProjNode* c = p->clone()->as_Proj();
3108 c->set_req(0, iff);
3109 return c;
3110 }
3111
3112 //------------------------------ short_circuit_if -------------------------------------
3113 // Force the iff control output to be the live_proj
3114 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
3115 guarantee(live_proj != nullptr, "null projection");
3116 int proj_con = live_proj->_con;
3117 assert(proj_con == 0 || proj_con == 1, "false or true projection");
3118 Node* con = intcon(proj_con);
3119 if (iff) {
3120 iff->set_req(1, con);
3121 }
3122 return con;
3123 }
3124
3125 //------------------------------ insert_if_before_proj -------------------------------------
3126 // Insert a new if before an if projection (* - new node)
3127 //
3128 // before
3129 // if(test)
3130 // / \
3131 // v v
3132 // other-proj proj (arg)
3133 //
3134 // after
3135 // if(test)
3136 // / \
3137 // / v
3138 // | * proj-clone
3139 // v |
3140 // other-proj v
3141 // * new_if(relop(cmp[IU](left,right)))
3142 // / \
3143 // v v
3144 // * new-proj proj
3145 // (returned)
3146 //
3147 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
3148 IfNode* iff = proj->in(0)->as_If();
3149 IdealLoopTree *loop = get_loop(proj);
3150 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3151 uint ddepth = dom_depth(proj);
3152
3153 _igvn.rehash_node_delayed(iff);
3154 _igvn.rehash_node_delayed(proj);
3155
3156 proj->set_req(0, nullptr); // temporary disconnect
3157 ProjNode* proj2 = proj_clone(proj, iff);
3158 register_node(proj2, loop, iff, ddepth);
3159
3160 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
3161 register_node(cmp, loop, proj2, ddepth);
3162
3163 BoolNode* bol = new BoolNode(cmp, relop);
3164 register_node(bol, loop, proj2, ddepth);
3165
3166 int opcode = iff->Opcode();
3167 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
3168 IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
3169 register_node(new_if, loop, proj2, ddepth);
3170
3171 proj->set_req(0, new_if); // reattach
3172 set_idom(proj, new_if, ddepth);
3173
3174 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
3175 guarantee(new_exit != nullptr, "null exit node");
3176 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
3177
3178 return new_exit;
3179 }
3180
3181 //------------------------------ insert_region_before_proj -------------------------------------
3182 // Insert a region before an if projection (* - new node)
3183 //
3184 // before
3185 // if(test)
3186 // / |
3187 // v |
3188 // proj v
3189 // other-proj
3190 //
3191 // after
3192 // if(test)
3193 // / |
3194 // v |
3195 // * proj-clone v
3196 // | other-proj
3197 // v
3198 // * new-region
3199 // |
3200 // v
3201 // * dum_if
3202 // / \
3203 // v \
3204 // * dum-proj v
3205 // proj
3206 //
3207 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3208 IfNode* iff = proj->in(0)->as_If();
3209 IdealLoopTree *loop = get_loop(proj);
3210 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3211 uint ddepth = dom_depth(proj);
3212
3213 _igvn.rehash_node_delayed(iff);
3214 _igvn.rehash_node_delayed(proj);
3215
3216 proj->set_req(0, nullptr); // temporary disconnect
3217 ProjNode* proj2 = proj_clone(proj, iff);
3218 register_node(proj2, loop, iff, ddepth);
3219
3220 RegionNode* reg = new RegionNode(2);
3221 reg->set_req(1, proj2);
3222 register_node(reg, loop, iff, ddepth);
3223
3224 IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3225 register_node(dum_if, loop, reg, ddepth);
3226
3227 proj->set_req(0, dum_if); // reattach
3228 set_idom(proj, dum_if, ddepth);
3229
3230 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3231 register_node(dum_proj, loop, dum_if, ddepth);
3232
3233 return reg;
3234 }
3235
3236 // Idea
3237 // ----
3238 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3239 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3240 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3241 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3242 // test alone instead:
3243 //
3244 // Before Partial Peeling:
3245 // Loop:
3246 // <peeled section>
3247 // Split off signed loop exit test
3248 // <-- CUT HERE -->
3249 // Unchanged unsigned loop exit test
3250 // <rest of unpeeled section>
3251 // goto Loop
3252 //
3253 // After Partial Peeling:
3254 // <cloned peeled section>
3255 // Cloned split off signed loop exit test
3256 // Loop:
3257 // Unchanged unsigned loop exit test
3258 // <rest of unpeeled section>
3259 // <peeled section>
3260 // Split off signed loop exit test
3261 // goto Loop
3262 //
3263 // Details
3264 // -------
3265 // Before:
3266 // if (i <u limit) Unsigned loop exit condition
3267 // / |
3268 // v v
3269 // exit-proj stay-in-loop-proj
3270 //
3271 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3272 // before the CmpU on the stay-in-loop path and keep both tests:
3273 //
3274 // if (i <u limit) Signed loop exit test
3275 // / |
3276 // / if (i <u limit) Unsigned loop exit test
3277 // / / |
3278 // v v v
3279 // exit-region stay-in-loop-proj
3280 //
3281 // Implementation
3282 // --------------
3283 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3284 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3285 // exit tests is preserved, and their loop nesting is correct.
3286 //
3287 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3288 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3289 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3290 //
3291 // if (stay-in-loop-const) Killed original unsigned loop exit test
3292 // / |
3293 // / v
3294 // / if (i < limit) Split off signed loop exit test
3295 // / / |
3296 // / / v
3297 // / / if (i <u limit) Cloned unsigned loop exit test
3298 // / / / |
3299 // v v v |
3300 // exit-region |
3301 // | |
3302 // dummy-if |
3303 // / | |
3304 // dead | |
3305 // v v
3306 // exit-proj stay-in-loop-proj
3307 //
3308 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3309 // loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3310 //
3311 // Requirements
3312 // ------------
3313 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3314 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3315 // Otherwise, we need to bail out (see comments in the code below).
3316 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3317 const bool Signed = true;
3318 const bool Unsigned = false;
3319
3320 BoolNode* bol = if_cmpu->in(1)->as_Bool();
3321 if (bol->_test._test != BoolTest::lt) {
3322 return nullptr;
3323 }
3324 CmpNode* cmpu = bol->in(1)->as_Cmp();
3325 assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3326
3327 int stride = stride_of_possible_iv(if_cmpu);
3328 if (stride == 0) {
3329 return nullptr;
3330 }
3331
3332 Node* lp_proj = stay_in_loop(if_cmpu, loop);
3333 guarantee(lp_proj != nullptr, "null loop node");
3334
3335 ProjNode* lp_continue = lp_proj->as_Proj();
3336 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3337 if (!lp_exit->is_IfFalse()) {
3338 // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3339 // We therefore can't add a single exit condition.
3340 return nullptr;
3341 }
3342 // The unsigned loop exit condition is
3343 // !(i <u limit)
3344 // = i >=u limit
3345 //
3346 // First, we note that for any x for which
3347 // 0 <= x <= INT_MAX
3348 // we can convert x to an unsigned int and still get the same guarantee:
3349 // 0 <= (uint) x <= INT_MAX = (uint) INT_MAX
3350 // 0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX (LEMMA)
3351 //
3352 // With that in mind, if
3353 // limit >= 0 (COND)
3354 // then the unsigned loop exit condition
3355 // i >=u limit (ULE)
3356 // is equivalent to
3357 // i < 0 || i >= limit (SLE-full)
3358 // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3359 // (uint) i >=u MAX_INT >= limit >= 0
3360 // or otherwise
3361 // i >= limit >= 0
3362 // holds due to (LEMMA).
3363 //
3364 // For completeness, a counterexample with limit < 0:
3365 // Assume i = -3 and limit = -2:
3366 // i < 0
3367 // -2 < 0
3368 // is true and thus also "i < 0 || i >= limit". But
3369 // i >=u limit
3370 // -3 >=u -2
3371 // is false.
3372 Node* limit = cmpu->in(2);
3373 const TypeInt* type_limit = _igvn.type(limit)->is_int();
3374 if (type_limit->_lo < 0) {
3375 return nullptr;
3376 }
3377
3378 // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3379 // stride < 0:
3380 // i < 0 (SLE = SLE-negative)
3381 // stride > 0:
3382 // i >= limit (SLE = SLE-positive)
3383 // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3384 //
3385 // Loop:
3386 // <peeled section>
3387 // i >= limit (SLE-positive)
3388 // <-- CUT HERE -->
3389 // i >=u limit (ULE)
3390 // <rest of unpeeled section>
3391 // goto Loop
3392 //
3393 // We exit the loop if:
3394 // (SLE) is true OR (ULE) is true
3395 // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3396 // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3397 // (SLE) IMPLIES (ULE)
3398 // This indeed holds when (COND) is given:
3399 // - stride > 0:
3400 // i >= limit // (SLE = SLE-positive)
3401 // i >= limit >= 0 // (COND)
3402 // i >=u limit >= 0 // (LEMMA)
3403 // which is the unsigned loop exit condition (ULE).
3404 // - stride < 0:
3405 // i < 0 // (SLE = SLE-negative)
3406 // (uint) i >u MAX_INT // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3407 // MAX_INT >= limit >= 0 // (COND)
3408 // MAX_INT >=u limit >= 0 // (LEMMA)
3409 // and thus from (NEG) and (LEMMA):
3410 // i >=u limit
3411 // which is the unsigned loop exit condition (ULE).
3412 //
3413 //
3414 // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3415 // <cloned peeled section>
3416 // i >= limit (SLE-positive)
3417 // Loop:
3418 // i >=u limit (ULE)
3419 // <rest of unpeeled section>
3420 // <peeled section>
3421 // i >= limit (SLE-positive)
3422 // goto Loop
3423 Node* rhs_cmpi;
3424 if (stride > 0) {
3425 rhs_cmpi = limit; // For i >= limit
3426 } else {
3427 rhs_cmpi = makecon(TypeInt::ZERO); // For i < 0
3428 }
3429 // Create a new region on the exit path
3430 RegionNode* reg = insert_region_before_proj(lp_exit);
3431 guarantee(reg != nullptr, "null region node");
3432
3433 // Clone the if-cmpu-true-false using a signed compare
3434 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3435 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3436 reg->add_req(cmpi_exit);
3437
3438 // Clone the if-cmpu-true-false
3439 BoolTest::mask rel_u = bol->_test._test;
3440 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3441 reg->add_req(cmpu_exit);
3442
3443 // Force original if to stay in loop.
3444 short_circuit_if(if_cmpu, lp_continue);
3445
3446 return cmpi_exit->in(0)->as_If();
3447 }
3448
3449 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3450 // Remove a previously inserted signed compare loop exit.
3451 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3452 Node* lp_proj = stay_in_loop(if_cmp, loop);
3453 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3454 stay_in_loop(lp_proj, loop)->is_If() &&
3455 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3456 Node* con = makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3457 if_cmp->set_req(1, con);
3458 }
3459
3460 //------------------------------ scheduled_nodelist -------------------------------------
3461 // Create a post order schedule of nodes that are in the
3462 // "member" set. The list is returned in "sched".
3463 // The first node in "sched" is the loop head, followed by
3464 // nodes which have no inputs in the "member" set, and then
3465 // followed by the nodes that have an immediate input dependence
3466 // on a node in "sched".
3467 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3468
3469 assert(member.test(loop->_head->_idx), "loop head must be in member set");
3470 VectorSet visited;
3471 Node_Stack nstack(loop->_body.size());
3472
3473 Node* n = loop->_head; // top of stack is cached in "n"
3474 uint idx = 0;
3475 visited.set(n->_idx);
3476
3477 // Initially push all with no inputs from within member set
3478 for(uint i = 0; i < loop->_body.size(); i++ ) {
3479 Node *elt = loop->_body.at(i);
3480 if (member.test(elt->_idx)) {
3481 bool found = false;
3482 for (uint j = 0; j < elt->req(); j++) {
3483 Node* def = elt->in(j);
3484 if (def && member.test(def->_idx) && def != elt) {
3485 found = true;
3486 break;
3487 }
3488 }
3489 if (!found && elt != loop->_head) {
3490 nstack.push(n, idx);
3491 n = elt;
3492 assert(!visited.test(n->_idx), "not seen yet");
3493 visited.set(n->_idx);
3494 }
3495 }
3496 }
3497
3498 // traverse out's that are in the member set
3499 while (true) {
3500 if (idx < n->outcnt()) {
3501 Node* use = n->raw_out(idx);
3502 idx++;
3503 if (!visited.test_set(use->_idx)) {
3504 if (member.test(use->_idx)) {
3505 nstack.push(n, idx);
3506 n = use;
3507 idx = 0;
3508 }
3509 }
3510 } else {
3511 // All outputs processed
3512 sched.push(n);
3513 if (nstack.is_empty()) break;
3514 n = nstack.node();
3515 idx = nstack.index();
3516 nstack.pop();
3517 }
3518 }
3519 }
3520
3521
3522 //------------------------------ has_use_in_set -------------------------------------
3523 // Has a use in the vector set
3524 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3525 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3526 Node* use = n->fast_out(j);
3527 if (vset.test(use->_idx)) {
3528 return true;
3529 }
3530 }
3531 return false;
3532 }
3533
3534
3535 //------------------------------ has_use_internal_to_set -------------------------------------
3536 // Has use internal to the vector set (ie. not in a phi at the loop head)
3537 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3538 Node* head = loop->_head;
3539 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3540 Node* use = n->fast_out(j);
3541 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3542 return true;
3543 }
3544 }
3545 return false;
3546 }
3547
3548
3549 //------------------------------ clone_for_use_outside_loop -------------------------------------
3550 // clone "n" for uses that are outside of loop
3551 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3552 int cloned = 0;
3553 assert(worklist.size() == 0, "should be empty");
3554 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3555 Node* use = n->fast_out(j);
3556 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3557 worklist.push(use);
3558 }
3559 }
3560
3561 if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3562 "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3563 return -1;
3564 }
3565
3566 while( worklist.size() ) {
3567 Node *use = worklist.pop();
3568 if (!has_node(use) || use->in(0) == C->top()) continue;
3569 uint j;
3570 for (j = 0; j < use->req(); j++) {
3571 if (use->in(j) == n) break;
3572 }
3573 assert(j < use->req(), "must be there");
3574
3575 // clone "n" and insert it between the inputs of "n" and the use outside the loop
3576 Node* n_clone = n->clone();
3577 _igvn.replace_input_of(use, j, n_clone);
3578 cloned++;
3579 Node* use_c;
3580 if (!use->is_Phi()) {
3581 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3582 } else {
3583 // Use in a phi is considered a use in the associated predecessor block
3584 use_c = use->in(0)->in(j);
3585 }
3586 set_ctrl(n_clone, use_c);
3587 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3588 get_loop(use_c)->_body.push(n_clone);
3589 _igvn.register_new_node_with_optimizer(n_clone);
3590 #ifndef PRODUCT
3591 if (TracePartialPeeling) {
3592 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3593 }
3594 #endif
3595 }
3596 return cloned;
3597 }
3598
3599
3600 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3601 // clone "n" for special uses that are in the not_peeled region.
3602 // If these def-uses occur in separate blocks, the code generator
3603 // marks the method as not compilable. For example, if a "BoolNode"
3604 // is in a different basic block than the "IfNode" that uses it, then
3605 // the compilation is aborted in the code generator.
3606 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3607 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3608 if (n->is_Phi() || n->is_Load()) {
3609 return;
3610 }
3611 assert(worklist.size() == 0, "should be empty");
3612 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3613 Node* use = n->fast_out(j);
3614 if ( not_peel.test(use->_idx) &&
3615 (use->is_If() || use->is_CMove() || use->is_Bool() || use->is_OpaqueInitializedAssertionPredicate()) &&
3616 use->in(1) == n) {
3617 worklist.push(use);
3618 }
3619 }
3620 if (worklist.size() > 0) {
3621 // clone "n" and insert it between inputs of "n" and the use
3622 Node* n_clone = n->clone();
3623 loop->_body.push(n_clone);
3624 _igvn.register_new_node_with_optimizer(n_clone);
3625 set_ctrl(n_clone, get_ctrl(n));
3626 sink_list.push(n_clone);
3627 not_peel.set(n_clone->_idx);
3628 #ifndef PRODUCT
3629 if (TracePartialPeeling) {
3630 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3631 }
3632 #endif
3633 while( worklist.size() ) {
3634 Node *use = worklist.pop();
3635 _igvn.rehash_node_delayed(use);
3636 for (uint j = 1; j < use->req(); j++) {
3637 if (use->in(j) == n) {
3638 use->set_req(j, n_clone);
3639 }
3640 }
3641 }
3642 }
3643 }
3644
3645
3646 //------------------------------ insert_phi_for_loop -------------------------------------
3647 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3648 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3649 Node *phi = PhiNode::make(lp, back_edge_val);
3650 phi->set_req(LoopNode::EntryControl, lp_entry_val);
3651 // Use existing phi if it already exists
3652 Node *hit = _igvn.hash_find_insert(phi);
3653 if( hit == nullptr ) {
3654 _igvn.register_new_node_with_optimizer(phi);
3655 set_ctrl(phi, lp);
3656 } else {
3657 // Remove the new phi from the graph and use the hit
3658 _igvn.remove_dead_node(phi);
3659 phi = hit;
3660 }
3661 _igvn.replace_input_of(use, idx, phi);
3662 }
3663
3664 #ifdef ASSERT
3665 //------------------------------ is_valid_loop_partition -------------------------------------
3666 // Validate the loop partition sets: peel and not_peel
3667 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3668 VectorSet& not_peel ) {
3669 uint i;
3670 // Check that peel_list entries are in the peel set
3671 for (i = 0; i < peel_list.size(); i++) {
3672 if (!peel.test(peel_list.at(i)->_idx)) {
3673 return false;
3674 }
3675 }
3676 // Check at loop members are in one of peel set or not_peel set
3677 for (i = 0; i < loop->_body.size(); i++ ) {
3678 Node *def = loop->_body.at(i);
3679 uint di = def->_idx;
3680 // Check that peel set elements are in peel_list
3681 if (peel.test(di)) {
3682 if (not_peel.test(di)) {
3683 return false;
3684 }
3685 // Must be in peel_list also
3686 bool found = false;
3687 for (uint j = 0; j < peel_list.size(); j++) {
3688 if (peel_list.at(j)->_idx == di) {
3689 found = true;
3690 break;
3691 }
3692 }
3693 if (!found) {
3694 return false;
3695 }
3696 } else if (not_peel.test(di)) {
3697 if (peel.test(di)) {
3698 return false;
3699 }
3700 } else {
3701 return false;
3702 }
3703 }
3704 return true;
3705 }
3706
3707 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3708 // Ensure a use outside of loop is of the right form
3709 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3710 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3711 return (use->is_Phi() &&
3712 use_c->is_Region() && use_c->req() == 3 &&
3713 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3714 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3715 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3716 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3717 }
3718
3719 //------------------------------ is_valid_clone_loop_form -------------------------------------
3720 // Ensure that all uses outside of loop are of the right form
3721 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3722 uint orig_exit_idx, uint clone_exit_idx) {
3723 uint len = peel_list.size();
3724 for (uint i = 0; i < len; i++) {
3725 Node *def = peel_list.at(i);
3726
3727 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3728 Node *use = def->fast_out(j);
3729 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3730 if (!loop->is_member(get_loop(use_c))) {
3731 // use is not in the loop, check for correct structure
3732 if (use->in(0) == def) {
3733 // Okay
3734 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3735 return false;
3736 }
3737 }
3738 }
3739 }
3740 return true;
3741 }
3742 #endif
3743
3744 //------------------------------ partial_peel -------------------------------------
3745 // Partially peel (aka loop rotation) the top portion of a loop (called
3746 // the peel section below) by cloning it and placing one copy just before
3747 // the new loop head and the other copy at the bottom of the new loop.
3748 //
3749 // before after where it came from
3750 //
3751 // stmt1 stmt1
3752 // loop: stmt2 clone
3753 // stmt2 if condA goto exitA clone
3754 // if condA goto exitA new_loop: new
3755 // stmt3 stmt3 clone
3756 // if !condB goto loop if condB goto exitB clone
3757 // exitB: stmt2 orig
3758 // stmt4 if !condA goto new_loop orig
3759 // exitA: goto exitA
3760 // exitB:
3761 // stmt4
3762 // exitA:
3763 //
3764 // Step 1: find the cut point: an exit test on probable
3765 // induction variable.
3766 // Step 2: schedule (with cloning) operations in the peel
3767 // section that can be executed after the cut into
3768 // the section that is not peeled. This may need
3769 // to clone operations into exit blocks. For
3770 // instance, a reference to A[i] in the not-peel
3771 // section and a reference to B[i] in an exit block
3772 // may cause a left-shift of i by 2 to be placed
3773 // in the peel block. This step will clone the left
3774 // shift into the exit block and sink the left shift
3775 // from the peel to the not-peel section.
3776 // Step 3: clone the loop, retarget the control, and insert
3777 // phis for values that are live across the new loop
3778 // head. This is very dependent on the graph structure
3779 // from clone_loop. It creates region nodes for
3780 // exit control and associated phi nodes for values
3781 // flow out of the loop through that exit. The region
3782 // node is dominated by the clone's control projection.
3783 // So the clone's peel section is placed before the
3784 // new loop head, and the clone's not-peel section is
3785 // forms the top part of the new loop. The original
3786 // peel section forms the tail of the new loop.
3787 // Step 4: update the dominator tree and recompute the
3788 // dominator depth.
3789 //
3790 // orig
3791 //
3792 // stmt1
3793 // |
3794 // v
3795 // predicates
3796 // |
3797 // v
3798 // loop<----+
3799 // | |
3800 // stmt2 |
3801 // | |
3802 // v |
3803 // ifA |
3804 // / | |
3805 // v v |
3806 // false true ^ <-- last_peel
3807 // / | |
3808 // / ===|==cut |
3809 // / stmt3 | <-- first_not_peel
3810 // / | |
3811 // | v |
3812 // v ifB |
3813 // exitA: / \ |
3814 // / \ |
3815 // v v |
3816 // false true |
3817 // / \ |
3818 // / ----+
3819 // |
3820 // v
3821 // exitB:
3822 // stmt4
3823 //
3824 //
3825 // after clone loop
3826 //
3827 // stmt1
3828 // |
3829 // v
3830 // predicates
3831 // / \
3832 // clone / \ orig
3833 // / \
3834 // / \
3835 // v v
3836 // +---->loop loop<----+
3837 // | | | |
3838 // | stmt2 stmt2 |
3839 // | | | |
3840 // | v v |
3841 // | ifA ifA |
3842 // | | \ / | |
3843 // | v v v v |
3844 // ^ true false false true ^ <-- last_peel
3845 // | | ^ \ / | |
3846 // | cut==|== \ \ / ===|==cut |
3847 // | stmt3 \ \ / stmt3 | <-- first_not_peel
3848 // | | dom | | | |
3849 // | v \ 1v v2 v |
3850 // | ifB regionA ifB |
3851 // | / \ | / \ |
3852 // | / \ v / \ |
3853 // | v v exitA: v v |
3854 // | true false false true |
3855 // | / ^ \ / \ |
3856 // +---- \ \ / ----+
3857 // dom \ /
3858 // \ 1v v2
3859 // regionB
3860 // |
3861 // v
3862 // exitB:
3863 // stmt4
3864 //
3865 //
3866 // after partial peel
3867 //
3868 // stmt1
3869 // |
3870 // v
3871 // predicates
3872 // /
3873 // clone / orig
3874 // / TOP
3875 // / \
3876 // v v
3877 // TOP->loop loop----+
3878 // | | |
3879 // stmt2 stmt2 |
3880 // | | |
3881 // v v |
3882 // ifA ifA |
3883 // | \ / | |
3884 // v v v v |
3885 // true false false true | <-- last_peel
3886 // | ^ \ / +------|---+
3887 // +->newloop \ \ / === ==cut | |
3888 // | stmt3 \ \ / TOP | |
3889 // | | dom | | stmt3 | | <-- first_not_peel
3890 // | v \ 1v v2 v | |
3891 // | ifB regionA ifB ^ v
3892 // | / \ | / \ | |
3893 // | / \ v / \ | |
3894 // | v v exitA: v v | |
3895 // | true false false true | |
3896 // | / ^ \ / \ | |
3897 // | | \ \ / v | |
3898 // | | dom \ / TOP | |
3899 // | | \ 1v v2 | |
3900 // ^ v regionB | |
3901 // | | | | |
3902 // | | v ^ v
3903 // | | exitB: | |
3904 // | | stmt4 | |
3905 // | +------------>-----------------+ |
3906 // | |
3907 // +-----------------<---------------------+
3908 //
3909 //
3910 // final graph
3911 //
3912 // stmt1
3913 // |
3914 // v
3915 // predicates
3916 // |
3917 // v
3918 // stmt2 clone
3919 // |
3920 // v
3921 // ........> ifA clone
3922 // : / |
3923 // dom / |
3924 // : v v
3925 // : false true
3926 // : | |
3927 // : | v
3928 // : | newloop<-----+
3929 // : | | |
3930 // : | stmt3 clone |
3931 // : | | |
3932 // : | v |
3933 // : | ifB |
3934 // : | / \ |
3935 // : | v v |
3936 // : | false true |
3937 // : | | | |
3938 // : | v stmt2 |
3939 // : | exitB: | |
3940 // : | stmt4 v |
3941 // : | ifA orig |
3942 // : | / \ |
3943 // : | / \ |
3944 // : | v v |
3945 // : | false true |
3946 // : | / \ |
3947 // : v v -----+
3948 // RegionA
3949 // |
3950 // v
3951 // exitA
3952 //
3953 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3954
3955 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3956 if (!loop->_head->is_Loop()) {
3957 return false;
3958 }
3959 LoopNode *head = loop->_head->as_Loop();
3960
3961 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3962 return false;
3963 }
3964
3965 // Check for complex exit control
3966 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3967 Node *n = loop->_body.at(ii);
3968 int opc = n->Opcode();
3969 if (n->is_Call() ||
3970 opc == Op_Catch ||
3971 opc == Op_CatchProj ||
3972 opc == Op_Jump ||
3973 opc == Op_JumpProj) {
3974 #ifndef PRODUCT
3975 if (TracePartialPeeling) {
3976 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3977 }
3978 #endif
3979 return false;
3980 }
3981 }
3982
3983 int dd = dom_depth(head);
3984
3985 // Step 1: find cut point
3986
3987 // Walk up dominators to loop head looking for first loop exit
3988 // which is executed on every path thru loop.
3989 IfNode *peel_if = nullptr;
3990 IfNode *peel_if_cmpu = nullptr;
3991
3992 Node *iff = loop->tail();
3993 while (iff != head) {
3994 if (iff->is_If()) {
3995 Node *ctrl = get_ctrl(iff->in(1));
3996 if (ctrl->is_top()) return false; // Dead test on live IF.
3997 // If loop-varying exit-test, check for induction variable
3998 if (loop->is_member(get_loop(ctrl)) &&
3999 loop->is_loop_exit(iff) &&
4000 is_possible_iv_test(iff)) {
4001 Node* cmp = iff->in(1)->in(1);
4002 if (cmp->Opcode() == Op_CmpI) {
4003 peel_if = iff->as_If();
4004 } else {
4005 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
4006 peel_if_cmpu = iff->as_If();
4007 }
4008 }
4009 }
4010 iff = idom(iff);
4011 }
4012
4013 // Prefer signed compare over unsigned compare.
4014 IfNode* new_peel_if = nullptr;
4015 if (peel_if == nullptr) {
4016 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
4017 return false; // No peel point found
4018 }
4019 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
4020 if (new_peel_if == nullptr) {
4021 return false; // No peel point found
4022 }
4023 peel_if = new_peel_if;
4024 }
4025 Node* last_peel = stay_in_loop(peel_if, loop);
4026 Node* first_not_peeled = stay_in_loop(last_peel, loop);
4027 if (first_not_peeled == nullptr || first_not_peeled == head) {
4028 return false;
4029 }
4030
4031 #ifndef PRODUCT
4032 if (TraceLoopOpts) {
4033 tty->print("PartialPeel ");
4034 loop->dump_head();
4035 }
4036
4037 if (TracePartialPeeling) {
4038 tty->print_cr("before partial peel one iteration");
4039 Node_List wl;
4040 Node* t = head->in(2);
4041 while (true) {
4042 wl.push(t);
4043 if (t == head) break;
4044 t = idom(t);
4045 }
4046 while (wl.size() > 0) {
4047 Node* tt = wl.pop();
4048 tt->dump();
4049 if (tt == last_peel) tty->print_cr("-- cut --");
4050 }
4051 }
4052 #endif
4053
4054 C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
4055
4056 VectorSet peel;
4057 VectorSet not_peel;
4058 Node_List peel_list;
4059 Node_List worklist;
4060 Node_List sink_list;
4061
4062 uint estimate = loop->est_loop_clone_sz(1);
4063 if (exceeding_node_budget(estimate)) {
4064 return false;
4065 }
4066
4067 // Set of cfg nodes to peel are those that are executable from
4068 // the head through last_peel.
4069 assert(worklist.size() == 0, "should be empty");
4070 worklist.push(head);
4071 peel.set(head->_idx);
4072 while (worklist.size() > 0) {
4073 Node *n = worklist.pop();
4074 if (n != last_peel) {
4075 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
4076 Node* use = n->fast_out(j);
4077 if (use->is_CFG() &&
4078 loop->is_member(get_loop(use)) &&
4079 !peel.test_set(use->_idx)) {
4080 worklist.push(use);
4081 }
4082 }
4083 }
4084 }
4085
4086 // Set of non-cfg nodes to peel are those that are control
4087 // dependent on the cfg nodes.
4088 for (uint i = 0; i < loop->_body.size(); i++) {
4089 Node *n = loop->_body.at(i);
4090 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
4091 if (peel.test(n_c->_idx)) {
4092 peel.set(n->_idx);
4093 } else {
4094 not_peel.set(n->_idx);
4095 }
4096 }
4097
4098 // Step 2: move operations from the peeled section down into the
4099 // not-peeled section
4100
4101 // Get a post order schedule of nodes in the peel region
4102 // Result in right-most operand.
4103 scheduled_nodelist(loop, peel, peel_list);
4104
4105 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4106
4107 // For future check for too many new phis
4108 uint old_phi_cnt = 0;
4109 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
4110 Node* use = head->fast_out(j);
4111 if (use->is_Phi()) old_phi_cnt++;
4112 }
4113
4114 #ifndef PRODUCT
4115 if (TracePartialPeeling) {
4116 tty->print_cr("\npeeled list");
4117 }
4118 #endif
4119
4120 // Evacuate nodes in peel region into the not_peeled region if possible
4121 bool too_many_clones = false;
4122 uint new_phi_cnt = 0;
4123 uint cloned_for_outside_use = 0;
4124 for (uint i = 0; i < peel_list.size();) {
4125 Node* n = peel_list.at(i);
4126 #ifndef PRODUCT
4127 if (TracePartialPeeling) n->dump();
4128 #endif
4129 bool incr = true;
4130 if (!n->is_CFG()) {
4131 if (has_use_in_set(n, not_peel)) {
4132 // If not used internal to the peeled region,
4133 // move "n" from peeled to not_peeled region.
4134 if (!has_use_internal_to_set(n, peel, loop)) {
4135 // if not pinned and not a load (which maybe anti-dependent on a store)
4136 // and not a CMove (Matcher expects only bool->cmove).
4137 if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
4138 int new_clones = clone_for_use_outside_loop(loop, n, worklist);
4139 if (C->failing()) return false;
4140 if (new_clones == -1) {
4141 too_many_clones = true;
4142 break;
4143 }
4144 cloned_for_outside_use += new_clones;
4145 sink_list.push(n);
4146 peel.remove(n->_idx);
4147 not_peel.set(n->_idx);
4148 peel_list.remove(i);
4149 incr = false;
4150 #ifndef PRODUCT
4151 if (TracePartialPeeling) {
4152 tty->print_cr("sink to not_peeled region: %d newbb: %d",
4153 n->_idx, get_ctrl(n)->_idx);
4154 }
4155 #endif
4156 }
4157 } else {
4158 // Otherwise check for special def-use cases that span
4159 // the peel/not_peel boundary such as bool->if
4160 clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
4161 new_phi_cnt++;
4162 }
4163 }
4164 }
4165 if (incr) i++;
4166 }
4167
4168 estimate += cloned_for_outside_use + new_phi_cnt;
4169 bool exceed_node_budget = !may_require_nodes(estimate);
4170 bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
4171
4172 if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
4173 #ifndef PRODUCT
4174 if (TracePartialPeeling && exceed_phi_limit) {
4175 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
4176 new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
4177 }
4178 #endif
4179 if (new_peel_if != nullptr) {
4180 remove_cmpi_loop_exit(new_peel_if, loop);
4181 }
4182 // Inhibit more partial peeling on this loop
4183 assert(!head->is_partial_peel_loop(), "not partial peeled");
4184 head->mark_partial_peel_failed();
4185 if (cloned_for_outside_use > 0) {
4186 // Terminate this round of loop opts because
4187 // the graph outside this loop was changed.
4188 C->set_major_progress();
4189 return true;
4190 }
4191 return false;
4192 }
4193
4194 // Step 3: clone loop, retarget control, and insert new phis
4195
4196 // Create new loop head for new phis and to hang
4197 // the nodes being moved (sinked) from the peel region.
4198 LoopNode* new_head = new LoopNode(last_peel, last_peel);
4199 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
4200 _igvn.register_new_node_with_optimizer(new_head);
4201 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
4202 _igvn.replace_input_of(first_not_peeled, 0, new_head);
4203 set_loop(new_head, loop);
4204 loop->_body.push(new_head);
4205 not_peel.set(new_head->_idx);
4206 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
4207 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
4208
4209 while (sink_list.size() > 0) {
4210 Node* n = sink_list.pop();
4211 set_ctrl(n, new_head);
4212 }
4213
4214 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4215
4216 clone_loop(loop, old_new, dd, IgnoreStripMined);
4217
4218 const uint clone_exit_idx = 1;
4219 const uint orig_exit_idx = 2;
4220 assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4221
4222 Node* head_clone = old_new[head->_idx];
4223 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
4224 Node* orig_tail_clone = head_clone->in(2);
4225
4226 // Add phi if "def" node is in peel set and "use" is not
4227
4228 for (uint i = 0; i < peel_list.size(); i++) {
4229 Node *def = peel_list.at(i);
4230 if (!def->is_CFG()) {
4231 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4232 Node *use = def->fast_out(j);
4233 if (has_node(use) && use->in(0) != C->top() &&
4234 (!peel.test(use->_idx) ||
4235 (use->is_Phi() && use->in(0) == head)) ) {
4236 worklist.push(use);
4237 }
4238 }
4239 while( worklist.size() ) {
4240 Node *use = worklist.pop();
4241 for (uint j = 1; j < use->req(); j++) {
4242 Node* n = use->in(j);
4243 if (n == def) {
4244
4245 // "def" is in peel set, "use" is not in peel set
4246 // or "use" is in the entry boundary (a phi) of the peel set
4247
4248 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4249
4250 if ( loop->is_member(get_loop( use_c )) ) {
4251 // use is in loop
4252 if (old_new[use->_idx] != nullptr) { // null for dead code
4253 Node* use_clone = old_new[use->_idx];
4254 _igvn.replace_input_of(use, j, C->top());
4255 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4256 }
4257 } else {
4258 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4259 // use is not in the loop, check if the live range includes the cut
4260 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4261 if (not_peel.test(lp_if->_idx)) {
4262 assert(j == orig_exit_idx, "use from original loop");
4263 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4264 }
4265 }
4266 }
4267 }
4268 }
4269 }
4270 }
4271
4272 // Step 3b: retarget control
4273
4274 // Redirect control to the new loop head if a cloned node in
4275 // the not_peeled region has control that points into the peeled region.
4276 // This necessary because the cloned peeled region will be outside
4277 // the loop.
4278 // from to
4279 // cloned-peeled <---+
4280 // new_head_clone: | <--+
4281 // cloned-not_peeled in(0) in(0)
4282 // orig-peeled
4283
4284 for (uint i = 0; i < loop->_body.size(); i++) {
4285 Node *n = loop->_body.at(i);
4286 if (!n->is_CFG() && n->in(0) != nullptr &&
4287 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4288 Node* n_clone = old_new[n->_idx];
4289 if (n_clone->depends_only_on_test()) {
4290 // Pin array access nodes: control is updated here to the loop head. If, after some transformations, the
4291 // backedge is removed, an array load could become dependent on a condition that's not a range check for that
4292 // access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
4293 // floating above its range check.
4294 Node* pinned_clone = n_clone->pin_array_access_node();
4295 if (pinned_clone != nullptr) {
4296 register_new_node_with_ctrl_of(pinned_clone, n_clone);
4297 old_new.map(n->_idx, pinned_clone);
4298 _igvn.replace_node(n_clone, pinned_clone);
4299 n_clone = pinned_clone;
4300 }
4301 }
4302 _igvn.replace_input_of(n_clone, 0, new_head_clone);
4303 }
4304 }
4305
4306 // Backedge of the surviving new_head (the clone) is original last_peel
4307 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4308
4309 // Cut first node in original not_peel set
4310 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
4311 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
4312 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
4313
4314 // Copy head_clone back-branch info to original head
4315 // and remove original head's loop entry and
4316 // clone head's back-branch
4317 _igvn.rehash_node_delayed(head); // Multiple edge updates
4318 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
4319 head->set_req(LoopNode::LoopBackControl, C->top());
4320 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4321
4322 // Similarly modify the phis
4323 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4324 Node* use = head->fast_out(k);
4325 if (use->is_Phi() && use->outcnt() > 0) {
4326 Node* use_clone = old_new[use->_idx];
4327 _igvn.rehash_node_delayed(use); // Multiple edge updates
4328 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
4329 use->set_req(LoopNode::LoopBackControl, C->top());
4330 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4331 }
4332 }
4333
4334 // Step 4: update dominator tree and dominator depth
4335
4336 set_idom(head, orig_tail_clone, dd);
4337 recompute_dom_depth();
4338
4339 // Inhibit more partial peeling on this loop
4340 new_head_clone->set_partial_peel_loop();
4341 C->set_major_progress();
4342 loop->record_for_igvn();
4343
4344 #ifndef PRODUCT
4345 if (TracePartialPeeling) {
4346 tty->print_cr("\nafter partial peel one iteration");
4347 Node_List wl;
4348 Node* t = last_peel;
4349 while (true) {
4350 wl.push(t);
4351 if (t == head_clone) break;
4352 t = idom(t);
4353 }
4354 while (wl.size() > 0) {
4355 Node* tt = wl.pop();
4356 if (tt == head) tty->print_cr("orig head");
4357 else if (tt == new_head_clone) tty->print_cr("new head");
4358 else if (tt == head_clone) tty->print_cr("clone head");
4359 tt->dump();
4360 }
4361 }
4362 #endif
4363
4364 C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4365
4366 return true;
4367 }
4368
4369 // Transform:
4370 //
4371 // loop<-----------------+
4372 // | |
4373 // stmt1 stmt2 .. stmtn |
4374 // | | | |
4375 // \ | / |
4376 // v v v |
4377 // region |
4378 // | |
4379 // shared_stmt |
4380 // | |
4381 // v |
4382 // if |
4383 // / \ |
4384 // | -----------+
4385 // v
4386 //
4387 // into:
4388 //
4389 // loop<-------------------+
4390 // | |
4391 // v |
4392 // +->loop |
4393 // | | |
4394 // | stmt1 stmt2 .. stmtn |
4395 // | | | | |
4396 // | | \ / |
4397 // | | v v |
4398 // | | region1 |
4399 // | | | |
4400 // | shared_stmt shared_stmt |
4401 // | | | |
4402 // | v v |
4403 // | if if |
4404 // | /\ / \ |
4405 // +-- | | -------+
4406 // \ /
4407 // v v
4408 // region2
4409 //
4410 // (region2 is shown to merge mirrored projections of the loop exit
4411 // ifs to make the diagram clearer but they really merge the same
4412 // projection)
4413 //
4414 // Conditions for this transformation to trigger:
4415 // - the path through stmt1 is frequent enough
4416 // - the inner loop will be turned into a counted loop after transformation
4417 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4418 if (!DuplicateBackedge) {
4419 return false;
4420 }
4421 assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4422 if (!loop->_head->is_Loop()) {
4423 return false;
4424 }
4425
4426 uint estimate = loop->est_loop_clone_sz(1);
4427 if (exceeding_node_budget(estimate)) {
4428 return false;
4429 }
4430
4431 LoopNode *head = loop->_head->as_Loop();
4432
4433 Node* region = nullptr;
4434 IfNode* exit_test = nullptr;
4435 uint inner;
4436 float f;
4437 if (StressDuplicateBackedge) {
4438 if (head->is_strip_mined()) {
4439 return false;
4440 }
4441 Node* c = head->in(LoopNode::LoopBackControl);
4442
4443 while (c != head) {
4444 if (c->is_Region()) {
4445 region = c;
4446 }
4447 c = idom(c);
4448 }
4449
4450 if (region == nullptr) {
4451 return false;
4452 }
4453
4454 inner = 1;
4455 } else {
4456 // Is the shape of the loop that of a counted loop...
4457 Node* back_control = loop_exit_control(head, loop);
4458 if (back_control == nullptr) {
4459 return false;
4460 }
4461
4462 BoolTest::mask bt = BoolTest::illegal;
4463 float cl_prob = 0;
4464 Node* incr = nullptr;
4465 Node* limit = nullptr;
4466 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4467 if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4468 return false;
4469 }
4470
4471 // With an extra phi for the candidate iv?
4472 // Or the region node is the loop head
4473 if (!incr->is_Phi() || incr->in(0) == head) {
4474 return false;
4475 }
4476
4477 PathFrequency pf(head, this);
4478 region = incr->in(0);
4479
4480 // Go over all paths for the extra phi's region and see if that
4481 // path is frequent enough and would match the expected iv shape
4482 // if the extra phi is removed
4483 inner = 0;
4484 for (uint i = 1; i < incr->req(); ++i) {
4485 Node* in = incr->in(i);
4486 Node* trunc1 = nullptr;
4487 Node* trunc2 = nullptr;
4488 const TypeInteger* iv_trunc_t = nullptr;
4489 Node* orig_in = in;
4490 if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4491 continue;
4492 }
4493 assert(in->Opcode() == Op_AddI, "wrong increment code");
4494 Node* xphi = nullptr;
4495 Node* stride = loop_iv_stride(in, xphi);
4496
4497 if (stride == nullptr) {
4498 continue;
4499 }
4500
4501 PhiNode* phi = loop_iv_phi(xphi, nullptr, head);
4502 if (phi == nullptr ||
4503 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4504 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4505 return false;
4506 }
4507
4508 f = pf.to(region->in(i));
4509 if (f > 0.5) {
4510 inner = i;
4511 break;
4512 }
4513 }
4514
4515 if (inner == 0) {
4516 return false;
4517 }
4518
4519 exit_test = back_control->in(0)->as_If();
4520 }
4521
4522 if (idom(region)->is_Catch()) {
4523 return false;
4524 }
4525
4526 // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4527 Unique_Node_List wq;
4528 wq.push(head->in(LoopNode::LoopBackControl));
4529 for (uint i = 0; i < wq.size(); i++) {
4530 Node* c = wq.at(i);
4531 assert(get_loop(c) == loop, "not in the right loop?");
4532 if (c->is_Region()) {
4533 if (c != region) {
4534 for (uint j = 1; j < c->req(); ++j) {
4535 wq.push(c->in(j));
4536 }
4537 }
4538 } else {
4539 wq.push(c->in(0));
4540 }
4541 assert(!is_strict_dominator(c, region), "shouldn't go above region");
4542 }
4543
4544 Node* region_dom = idom(region);
4545
4546 // Can't do the transformation if this would cause a membar pair to
4547 // be split
4548 for (uint i = 0; i < wq.size(); i++) {
4549 Node* c = wq.at(i);
4550 if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4551 assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4552 if (!wq.member(c->as_MemBar()->leading_membar())) {
4553 return false;
4554 }
4555 }
4556 }
4557 C->print_method(PHASE_BEFORE_DUPLICATE_LOOP_BACKEDGE, 4, head);
4558
4559 // Collect data nodes that need to be clones as well
4560 int dd = dom_depth(head);
4561
4562 for (uint i = 0; i < loop->_body.size(); ++i) {
4563 Node* n = loop->_body.at(i);
4564 if (has_ctrl(n)) {
4565 Node* c = get_ctrl(n);
4566 if (wq.member(c)) {
4567 wq.push(n);
4568 }
4569 } else {
4570 set_idom(n, idom(n), dd);
4571 }
4572 }
4573
4574 // clone shared_stmt
4575 clone_loop_body(wq, old_new, nullptr);
4576
4577 Node* region_clone = old_new[region->_idx];
4578 region_clone->set_req(inner, C->top());
4579 set_idom(region, region->in(inner), dd);
4580
4581 // Prepare the outer loop
4582 Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4583 register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4584 _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4585 set_idom(head, outer_head, dd);
4586
4587 fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4588
4589 // Make one of the shared_stmt copies only reachable from stmt1, the
4590 // other only from stmt2..stmtn.
4591 Node* dom = nullptr;
4592 for (uint i = 1; i < region->req(); ++i) {
4593 if (i != inner) {
4594 _igvn.replace_input_of(region, i, C->top());
4595 }
4596 Node* in = region_clone->in(i);
4597 if (in->is_top()) {
4598 continue;
4599 }
4600 if (dom == nullptr) {
4601 dom = in;
4602 } else {
4603 dom = dom_lca(dom, in);
4604 }
4605 }
4606
4607 set_idom(region_clone, dom, dd);
4608
4609 // Set up the outer loop
4610 for (uint i = 0; i < head->outcnt(); i++) {
4611 Node* u = head->raw_out(i);
4612 if (u->is_Phi()) {
4613 Node* outer_phi = u->clone();
4614 outer_phi->set_req(0, outer_head);
4615 Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4616 if (backedge == nullptr) {
4617 backedge = u->in(LoopNode::LoopBackControl);
4618 }
4619 outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4620 register_new_node(outer_phi, outer_head);
4621 _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4622 }
4623 }
4624
4625 // create control and data nodes for out of loop uses (including region2)
4626 Node_List worklist;
4627 uint new_counter = C->unique();
4628 fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4629
4630 Node_List *split_if_set = nullptr;
4631 Node_List *split_bool_set = nullptr;
4632 Node_List *split_cex_set = nullptr;
4633 fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4634 split_if_set, split_bool_set, split_cex_set);
4635
4636 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4637
4638 if (exit_test != nullptr) {
4639 float cnt = exit_test->_fcnt;
4640 if (cnt != COUNT_UNKNOWN) {
4641 exit_test->_fcnt = cnt * f;
4642 old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4643 }
4644 }
4645
4646 C->set_major_progress();
4647
4648 C->print_method(PHASE_AFTER_DUPLICATE_LOOP_BACKEDGE, 4, outer_head);
4649
4650 return true;
4651 }
4652
4653 // AutoVectorize the loop: replace scalar ops with vector ops.
4654 PhaseIdealLoop::AutoVectorizeStatus
4655 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4656 // Counted loop only
4657 if (!lpt->is_counted()) {
4658 return AutoVectorizeStatus::Impossible;
4659 }
4660
4661 // Main-loop only
4662 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4663 if (!cl->is_main_loop()) {
4664 return AutoVectorizeStatus::Impossible;
4665 }
4666
4667 VLoop vloop(lpt, false);
4668 if (!vloop.check_preconditions()) {
4669 return AutoVectorizeStatus::TriedAndFailed;
4670 }
4671
4672 // Ensure the shared data is cleared before each use
4673 vshared.clear();
4674
4675 const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4676 if (!vloop_analyzer.success()) {
4677 return AutoVectorizeStatus::TriedAndFailed;
4678 }
4679
4680 SuperWord sw(vloop_analyzer);
4681 if (!sw.transform_loop()) {
4682 return AutoVectorizeStatus::TriedAndFailed;
4683 }
4684
4685 return AutoVectorizeStatus::Success;
4686 }
4687
4688 // Just before insert_pre_post_loops, we can multiversion the loop:
4689 //
4690 // multiversion_if
4691 // | |
4692 // fast_loop slow_loop
4693 //
4694 // In the fast_loop we can make speculative assumptions, and put the
4695 // conditions into the multiversion_if. If the conditions hold at runtime,
4696 // we enter the fast_loop, if the conditions fail, we take the slow_loop
4697 // instead which does not make any of the speculative assumptions.
4698 //
4699 // Note: we only multiversion the loop if the loop does not have any
4700 // auto vectorization check Predicate. If we have that predicate,
4701 // then we can simply add the speculative assumption checks to
4702 // that Predicate. This means we do not need to duplicate the
4703 // loop - we have a smaller graph and save compile time. Should
4704 // the conditions ever fail, then we deopt / trap at the Predicate
4705 // and recompile without that Predicate. At that point we will
4706 // multiversion the loop, so that we can still have speculative
4707 // runtime checks.
4708 //
4709 // We perform the multiversioning when the loop is still in its single
4710 // iteration form, even before we insert pre and post loops. This makes
4711 // the cloning much simpler. However, this means that both the fast
4712 // and the slow loop have to be optimized independently (adding pre
4713 // and post loops, unrolling the main loop, auto-vectorize etc.). And
4714 // we may end up not needing any speculative assumptions in the fast_loop
4715 // and then rejecting the slow_loop by constant folding the multiversion_if.
4716 //
4717 // Therefore, we "delay" the optimization of the slow_loop until we add
4718 // at least one speculative assumption for the fast_loop. If we never
4719 // add such a speculative runtime check, the OpaqueMultiversioningNode
4720 // of the multiversion_if constant folds to true after loop opts, and the
4721 // multiversion_if folds away the "delayed" slow_loop. If we add any
4722 // speculative assumption, then we notify the OpaqueMultiversioningNode
4723 // with "notify_slow_loop_that_it_can_resume_optimizations".
4724 //
4725 // Note: new runtime checks can be added to the multiversion_if with
4726 // PhaseIdealLoop::create_new_if_for_multiversion
4727 void PhaseIdealLoop::maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new) {
4728 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4729 LoopNode* outer_loop = cl->skip_strip_mined();
4730 Node* entry = outer_loop->in(LoopNode::EntryControl);
4731
4732 // Check we have multiversioning enabled, and are not already multiversioned.
4733 if (!LoopMultiversioning || cl->is_multiversion()) { return; }
4734
4735 // Check that we do not have a parse-predicate where we can add the runtime checks
4736 // during auto-vectorization.
4737 const Predicates predicates(entry);
4738 const PredicateBlock* predicate_block = predicates.auto_vectorization_check_block();
4739 if (predicate_block->has_parse_predicate()) { return; }
4740
4741 // Check node budget.
4742 uint estimate = lpt->est_loop_clone_sz(2);
4743 if (!may_require_nodes(estimate)) { return; }
4744
4745 do_multiversioning(lpt, old_new);
4746 }
4747
4748 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4749 for (uint i = 0; i < _data_nodes.size(); i++) {
4750 clone(_data_nodes[i], new_ctrl);
4751 }
4752 }
4753
4754 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4755 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4756 Node* clone = node->clone();
4757 _phase->igvn().register_new_node_with_optimizer(clone);
4758 _orig_to_new.put(node, clone);
4759 _phase->set_ctrl(clone, new_ctrl);
4760 if (node->is_CastII()) {
4761 clone->set_req(0, new_ctrl);
4762 }
4763 }
4764
4765 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4766 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4767 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4768 _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4769 for (uint i = 1; i < node->req(); i++) {
4770 Node** cloned_input = _orig_to_new.get(node->in(i));
4771 if (cloned_input != nullptr) {
4772 // Input was also cloned -> rewire clone to the cloned input.
4773 _phase->igvn().replace_input_of(clone, i, *cloned_input);
4774 }
4775 }
4776 });
4777 }
4778
4779 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4780 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4781 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4782 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4783 Node* new_ctrl) {
4784 for (uint i = 0; i < _data_nodes.size(); i++) {
4785 Node* data_node = _data_nodes[i];
4786 if (data_node->is_Opaque1()) {
4787 transform_opaque_node(transform_strategy, data_node);
4788 } else {
4789 clone(data_node, new_ctrl);
4790 }
4791 }
4792 }
4793
4794 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4795 Node* transformed_node;
4796 if (node->is_OpaqueLoopInit()) {
4797 transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4798 } else {
4799 assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4800 transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4801 }
4802 // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4803 _orig_to_new.put(node, transformed_node);
4804 }