1 /*
2 * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/callnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/castnode.hpp"
35 #include "opto/divnode.hpp"
36 #include "opto/inlinetypenode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/matcher.hpp"
39 #include "opto/mulnode.hpp"
40 #include "opto/movenode.hpp"
41 #include "opto/opaquenode.hpp"
42 #include "opto/rootnode.hpp"
43 #include "opto/subnode.hpp"
44 #include "opto/subtypenode.hpp"
45 #include "opto/superword.hpp"
46 #include "opto/vectornode.hpp"
47 #include "utilities/macros.hpp"
48
49 //=============================================================================
50 //------------------------------split_thru_phi---------------------------------
51 // Split Node 'n' through merge point if there is enough win.
52 Node* PhaseIdealLoop::split_thru_phi(Node* n, Node* region, int policy) {
53 if ((n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) ||
54 (n->Opcode() == Op_ConvL2I && n->bottom_type() != TypeInt::INT)) {
55 // ConvI2L/ConvL2I may have type information on it which is unsafe to push up
56 // so disable this for now
57 return nullptr;
58 }
59
60 // Splitting range check CastIIs through a loop induction Phi can
61 // cause new Phis to be created that are left unrelated to the loop
62 // induction Phi and prevent optimizations (vectorization)
63 if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
64 n->in(1) == region->as_CountedLoop()->phi()) {
65 return nullptr;
66 }
67
68 // Inline types should not be split through Phis because they cannot be merged
69 // through Phi nodes but each value input needs to be merged individually.
70 if (n->is_InlineType()) {
71 return nullptr;
72 }
73
74 if (cannot_split_division(n, region)) {
75 return nullptr;
76 }
77
78 int wins = 0;
79 assert(!n->is_CFG(), "");
80 assert(region->is_Region(), "");
81
82 const Type* type = n->bottom_type();
83 const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
84 Node* phi;
85 if (t_oop != nullptr && t_oop->is_known_instance_field()) {
86 int iid = t_oop->instance_id();
87 int index = C->get_alias_index(t_oop);
88 int offset = t_oop->offset();
89 phi = new PhiNode(region, type, nullptr, iid, index, offset);
90 } else {
91 phi = PhiNode::make_blank(region, n);
92 }
93 uint old_unique = C->unique();
94 for (uint i = 1; i < region->req(); i++) {
95 Node* x;
96 Node* the_clone = nullptr;
97 if (region->in(i) == C->top()) {
98 x = C->top(); // Dead path? Use a dead data op
99 } else {
100 x = n->clone(); // Else clone up the data op
101 the_clone = x; // Remember for possible deletion.
102 // Alter data node to use pre-phi inputs
103 if (n->in(0) == region)
104 x->set_req( 0, region->in(i) );
105 for (uint j = 1; j < n->req(); j++) {
106 Node* in = n->in(j);
107 if (in->is_Phi() && in->in(0) == region)
108 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
109 }
110 }
111 // Check for a 'win' on some paths
112 const Type* t = x->Value(&_igvn);
113
114 bool singleton = t->singleton();
115
116 // A TOP singleton indicates that there are no possible values incoming
117 // along a particular edge. In most cases, this is OK, and the Phi will
118 // be eliminated later in an Ideal call. However, we can't allow this to
119 // happen if the singleton occurs on loop entry, as the elimination of
120 // the PhiNode may cause the resulting node to migrate back to a previous
121 // loop iteration.
122 if (singleton && t == Type::TOP) {
123 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
124 // irreducible loop may not be indicated by an affirmative is_Loop());
125 // therefore, the only top we can split thru a phi is on a backedge of
126 // a loop.
127 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
128 }
129
130 if (singleton) {
131 wins++;
132 x = ((PhaseGVN&)_igvn).makecon(t);
133 } else {
134 // We now call Identity to try to simplify the cloned node.
135 // Note that some Identity methods call phase->type(this).
136 // Make sure that the type array is big enough for
137 // our new node, even though we may throw the node away.
138 // (Note: This tweaking with igvn only works because x is a new node.)
139 _igvn.set_type(x, t);
140 // If x is a TypeNode, capture any more-precise type permanently into Node
141 // otherwise it will be not updated during igvn->transform since
142 // igvn->type(x) is set to x->Value() already.
143 x->raise_bottom_type(t);
144 Node* y = x->Identity(&_igvn);
145 if (y != x) {
146 wins++;
147 x = y;
148 } else {
149 y = _igvn.hash_find(x);
150 if (y == nullptr) {
151 y = similar_subtype_check(x, region->in(i));
152 }
153 if (y) {
154 wins++;
155 x = y;
156 } else {
157 // Else x is a new node we are keeping
158 // We do not need register_new_node_with_optimizer
159 // because set_type has already been called.
160 _igvn._worklist.push(x);
161 }
162 }
163 }
164
165 phi->set_req( i, x );
166
167 if (the_clone == nullptr) {
168 continue;
169 }
170
171 if (the_clone != x) {
172 _igvn.remove_dead_node(the_clone);
173 } else if (region->is_Loop() && i == LoopNode::LoopBackControl &&
174 n->is_Load() && can_move_to_inner_loop(n, region->as_Loop(), x)) {
175 // it is not a win if 'x' moved from an outer to an inner loop
176 // this edge case can only happen for Load nodes
177 wins = 0;
178 break;
179 }
180 }
181 // Too few wins?
182 if (wins <= policy) {
183 _igvn.remove_dead_node(phi);
184 return nullptr;
185 }
186
187 // Record Phi
188 register_new_node( phi, region );
189
190 for (uint i2 = 1; i2 < phi->req(); i2++) {
191 Node *x = phi->in(i2);
192 // If we commoned up the cloned 'x' with another existing Node,
193 // the existing Node picks up a new use. We need to make the
194 // existing Node occur higher up so it dominates its uses.
195 Node *old_ctrl;
196 IdealLoopTree *old_loop;
197
198 if (x->is_Con()) {
199 // Constant's control is always root.
200 set_ctrl(x, C->root());
201 continue;
202 }
203 // The occasional new node
204 if (x->_idx >= old_unique) { // Found a new, unplaced node?
205 old_ctrl = nullptr;
206 old_loop = nullptr; // Not in any prior loop
207 } else {
208 old_ctrl = get_ctrl(x);
209 old_loop = get_loop(old_ctrl); // Get prior loop
210 }
211 // New late point must dominate new use
212 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
213 if (new_ctrl == old_ctrl) // Nothing is changed
214 continue;
215
216 IdealLoopTree *new_loop = get_loop(new_ctrl);
217
218 // Don't move x into a loop if its uses are
219 // outside of loop. Otherwise x will be cloned
220 // for each use outside of this loop.
221 IdealLoopTree *use_loop = get_loop(region);
222 if (!new_loop->is_member(use_loop) &&
223 (old_loop == nullptr || !new_loop->is_member(old_loop))) {
224 // Take early control, later control will be recalculated
225 // during next iteration of loop optimizations.
226 new_ctrl = get_early_ctrl(x);
227 new_loop = get_loop(new_ctrl);
228 }
229 // Set new location
230 set_ctrl(x, new_ctrl);
231 // If changing loop bodies, see if we need to collect into new body
232 if (old_loop != new_loop) {
233 if (old_loop && !old_loop->_child)
234 old_loop->_body.yank(x);
235 if (!new_loop->_child)
236 new_loop->_body.push(x); // Collect body info
237 }
238 }
239
240 return phi;
241 }
242
243 // Test whether node 'x' can move into an inner loop relative to node 'n'.
244 // Note: The test is not exact. Returns true if 'x' COULD end up in an inner loop,
245 // BUT it can also return true and 'x' is in the outer loop
246 bool PhaseIdealLoop::can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x) {
247 IdealLoopTree* n_loop_tree = get_loop(n_loop);
248 IdealLoopTree* x_loop_tree = get_loop(get_early_ctrl(x));
249 // x_loop_tree should be outer or same loop as n_loop_tree
250 return !x_loop_tree->is_member(n_loop_tree);
251 }
252
253 // Subtype checks that carry profile data don't common so look for a replacement by following edges
254 Node* PhaseIdealLoop::similar_subtype_check(const Node* x, Node* r_in) {
255 if (x->is_SubTypeCheck()) {
256 Node* in1 = x->in(1);
257 for (DUIterator_Fast imax, i = in1->fast_outs(imax); i < imax; i++) {
258 Node* u = in1->fast_out(i);
259 if (u != x && u->is_SubTypeCheck() && u->in(1) == x->in(1) && u->in(2) == x->in(2)) {
260 for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
261 Node* bol = u->fast_out(j);
262 for (DUIterator_Fast kmax, k = bol->fast_outs(kmax); k < kmax; k++) {
263 Node* iff = bol->fast_out(k);
264 // Only dominating subtype checks are interesting: otherwise we risk replacing a subtype check by another with
265 // unrelated profile
266 if (iff->is_If() && is_dominator(iff, r_in)) {
267 return u;
268 }
269 }
270 }
271 }
272 }
273 }
274 return nullptr;
275 }
276
277 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
278 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
279 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
280 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
281 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
282 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
283 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
284 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
285 const Type* zero;
286 switch (n->Opcode()) {
287 case Op_DivI:
288 case Op_ModI:
289 zero = TypeInt::ZERO;
290 break;
291 case Op_DivL:
292 case Op_ModL:
293 zero = TypeLong::ZERO;
294 break;
295 default:
296 return false;
297 }
298
299 if (n->in(0) != nullptr) {
300 // Cannot split through phi if Div or Mod node has a control dependency to a zero check.
301 return true;
302 }
303
304 Node* divisor = n->in(2);
305 return is_divisor_loop_phi(divisor, region) &&
306 loop_phi_backedge_type_contains_zero(divisor, zero);
307 }
308
309 bool PhaseIdealLoop::is_divisor_loop_phi(const Node* divisor, const Node* loop) {
310 return loop->is_Loop() && divisor->is_Phi() && divisor->in(0) == loop;
311 }
312
313 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
314 return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
315 }
316
317 //------------------------------dominated_by------------------------------------
318 // Replace the dominated test with an obvious true or false. Place it on the
319 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
320 // live path up to the dominating control.
321 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool pin_array_access_nodes) {
322 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
323
324 // prevdom is the dominating projection of the dominating test.
325 assert(iff->Opcode() == Op_If ||
326 iff->Opcode() == Op_CountedLoopEnd ||
327 iff->Opcode() == Op_LongCountedLoopEnd ||
328 iff->Opcode() == Op_RangeCheck ||
329 iff->Opcode() == Op_ParsePredicate,
330 "Check this code when new subtype is added");
331
332 int pop = prevdom->Opcode();
333 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
334 if (flip) {
335 if (pop == Op_IfTrue)
336 pop = Op_IfFalse;
337 else
338 pop = Op_IfTrue;
339 }
340 // 'con' is set to true or false to kill the dominated test.
341 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
342 set_ctrl(con, C->root()); // Constant gets a new use
343 // Hack the dominated test
344 _igvn.replace_input_of(iff, 1, con);
345
346 // If I don't have a reachable TRUE and FALSE path following the IfNode then
347 // I can assume this path reaches an infinite loop. In this case it's not
348 // important to optimize the data Nodes - either the whole compilation will
349 // be tossed or this path (and all data Nodes) will go dead.
350 if (iff->outcnt() != 2) {
351 return;
352 }
353
354 // Make control-dependent data Nodes on the live path (path that will remain
355 // once the dominated IF is removed) become control-dependent on the
356 // dominating projection.
357 Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
358
359 if (dp == nullptr) {
360 return;
361 }
362
363 rewire_safe_outputs_to_dominator(dp, prevdom, pin_array_access_nodes);
364 }
365
366 void PhaseIdealLoop::rewire_safe_outputs_to_dominator(Node* source, Node* dominator, const bool pin_array_access_nodes) {
367 IdealLoopTree* old_loop = get_loop(source);
368
369 for (DUIterator_Fast imax, i = source->fast_outs(imax); i < imax; i++) {
370 Node* out = source->fast_out(i); // Control-dependent node
371 // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
372 if (out->depends_only_on_test() && _igvn.no_dependent_zero_check(out)) {
373 assert(out->in(0) == source, "must be control dependent on source");
374 _igvn.replace_input_of(out, 0, dominator);
375 if (pin_array_access_nodes) {
376 // Because of Loop Predication, Loads and range check Cast nodes that are control dependent on this range
377 // check (that is about to be removed) now depend on multiple dominating Hoisted Check Predicates. After the
378 // removal of this range check, these control dependent nodes end up at the lowest/nearest dominating predicate
379 // in the graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
380 // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the lowest
381 // dominating check.
382 Node* clone = out->pin_array_access_node();
383 if (clone != nullptr) {
384 clone = _igvn.register_new_node_with_optimizer(clone, out);
385 _igvn.replace_node(out, clone);
386 out = clone;
387 }
388 }
389 set_early_ctrl(out, false);
390 IdealLoopTree* new_loop = get_loop(get_ctrl(out));
391 if (old_loop != new_loop) {
392 if (!old_loop->_child) {
393 old_loop->_body.yank(out);
394 }
395 if (!new_loop->_child) {
396 new_loop->_body.push(out);
397 }
398 }
399 --i;
400 --imax;
401 }
402 }
403 }
404
405 //------------------------------has_local_phi_input----------------------------
406 // Return TRUE if 'n' has Phi inputs from its local block and no other
407 // block-local inputs (all non-local-phi inputs come from earlier blocks)
408 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
409 Node *n_ctrl = get_ctrl(n);
410 // See if some inputs come from a Phi in this block, or from before
411 // this block.
412 uint i;
413 for( i = 1; i < n->req(); i++ ) {
414 Node *phi = n->in(i);
415 if( phi->is_Phi() && phi->in(0) == n_ctrl )
416 break;
417 }
418 if( i >= n->req() )
419 return nullptr; // No Phi inputs; nowhere to clone thru
420
421 // Check for inputs created between 'n' and the Phi input. These
422 // must split as well; they have already been given the chance
423 // (courtesy of a post-order visit) and since they did not we must
424 // recover the 'cost' of splitting them by being very profitable
425 // when splitting 'n'. Since this is unlikely we simply give up.
426 for( i = 1; i < n->req(); i++ ) {
427 Node *m = n->in(i);
428 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
429 // We allow the special case of AddP's with no local inputs.
430 // This allows us to split-up address expressions.
431 if (m->is_AddP() &&
432 get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
433 get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
434 get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
435 // Move the AddP up to the dominating point. That's fine because control of m's inputs
436 // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
437 Node* c = find_non_split_ctrl(idom(n_ctrl));
438 if (c->is_OuterStripMinedLoop()) {
439 c->as_Loop()->verify_strip_mined(1);
440 c = c->in(LoopNode::EntryControl);
441 }
442 set_ctrl_and_loop(m, c);
443 continue;
444 }
445 return nullptr;
446 }
447 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
448 }
449
450 return n_ctrl;
451 }
452
453 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
454 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
455 assert(bt == T_INT || bt == T_LONG, "only for integers");
456 int n_op = n->Opcode();
457
458 if (n_op == Op_LShift(bt)) {
459 // Scale is loop invariant
460 Node* scale = n->in(2);
461 Node* scale_ctrl = get_ctrl(scale);
462 IdealLoopTree* scale_loop = get_loop(scale_ctrl);
463 if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
464 return nullptr;
465 }
466 const TypeInt* scale_t = scale->bottom_type()->isa_int();
467 if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
468 return nullptr; // Dont bother with byte/short masking
469 }
470 // Add must vary with loop (else shift would be loop-invariant)
471 Node* add = n->in(1);
472 Node* add_ctrl = get_ctrl(add);
473 IdealLoopTree* add_loop = get_loop(add_ctrl);
474 if (n_loop != add_loop) {
475 return nullptr; // happens w/ evil ZKM loops
476 }
477
478 // Convert I-V into I+ (0-V); same for V-I
479 if (add->Opcode() == Op_Sub(bt) &&
480 _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
481 assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
482 Node* zero = _igvn.integercon(0, bt);
483 set_ctrl(zero, C->root());
484 Node* neg = SubNode::make(zero, add->in(2), bt);
485 register_new_node_with_ctrl_of(neg, add->in(2));
486 add = AddNode::make(add->in(1), neg, bt);
487 register_new_node(add, add_ctrl);
488 }
489 if (add->Opcode() != Op_Add(bt)) return nullptr;
490 assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
491 // See if one add input is loop invariant
492 Node* add_var = add->in(1);
493 Node* add_var_ctrl = get_ctrl(add_var);
494 IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
495 Node* add_invar = add->in(2);
496 Node* add_invar_ctrl = get_ctrl(add_invar);
497 IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
498 if (add_invar_loop == n_loop) {
499 // Swap to find the invariant part
500 add_invar = add_var;
501 add_invar_ctrl = add_var_ctrl;
502 add_invar_loop = add_var_loop;
503 add_var = add->in(2);
504 } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
505 return nullptr;
506 }
507 if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
508 return nullptr; // No invariant part of the add?
509 }
510
511 // Yes! Reshape address expression!
512 Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
513 Node* inv_scale_ctrl =
514 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
515 add_invar_ctrl : scale_ctrl;
516 register_new_node(inv_scale, inv_scale_ctrl);
517 Node* var_scale = LShiftNode::make(add_var, scale, bt);
518 register_new_node(var_scale, n_ctrl);
519 Node* var_add = AddNode::make(var_scale, inv_scale, bt);
520 register_new_node(var_add, n_ctrl);
521 _igvn.replace_node(n, var_add);
522 return var_add;
523 }
524 return nullptr;
525 }
526
527 //------------------------------remix_address_expressions----------------------
528 // Rework addressing expressions to get the most loop-invariant stuff
529 // moved out. We'd like to do all associative operators, but it's especially
530 // important (common) to do address expressions.
531 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
532 if (!has_ctrl(n)) return nullptr;
533 Node* n_ctrl = get_ctrl(n);
534 IdealLoopTree* n_loop = get_loop(n_ctrl);
535
536 // See if 'n' mixes loop-varying and loop-invariant inputs and
537 // itself is loop-varying.
538
539 // Only interested in binary ops (and AddP)
540 if (n->req() < 3 || n->req() > 4) return nullptr;
541
542 Node* n1_ctrl = get_ctrl(n->in( 1));
543 Node* n2_ctrl = get_ctrl(n->in( 2));
544 Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
545 IdealLoopTree* n1_loop = get_loop(n1_ctrl);
546 IdealLoopTree* n2_loop = get_loop(n2_ctrl);
547 IdealLoopTree* n3_loop = get_loop(n3_ctrl);
548
549 // Does one of my inputs spin in a tighter loop than self?
550 if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
551 (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
552 (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
553 return nullptr; // Leave well enough alone
554 }
555
556 // Is at least one of my inputs loop-invariant?
557 if (n1_loop == n_loop &&
558 n2_loop == n_loop &&
559 n3_loop == n_loop) {
560 return nullptr; // No loop-invariant inputs
561 }
562
563 Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
564 if (res != nullptr) {
565 return res;
566 }
567 res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
568 if (res != nullptr) {
569 return res;
570 }
571
572 int n_op = n->Opcode();
573 // Replace (I+V) with (V+I)
574 if (n_op == Op_AddI ||
575 n_op == Op_AddL ||
576 n_op == Op_AddF ||
577 n_op == Op_AddD ||
578 n_op == Op_MulI ||
579 n_op == Op_MulL ||
580 n_op == Op_MulF ||
581 n_op == Op_MulD) {
582 if (n2_loop == n_loop) {
583 assert(n1_loop != n_loop, "");
584 n->swap_edges(1, 2);
585 }
586 }
587
588 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
589 // but not if I2 is a constant. Skip for irreducible loops.
590 if (n_op == Op_AddP && n_loop->_head->is_Loop()) {
591 if (n2_loop == n_loop && n3_loop != n_loop) {
592 if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
593 Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
594 Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
595 IdealLoopTree* n22loop = get_loop(n22_ctrl);
596 IdealLoopTree* n23_loop = get_loop(n23_ctrl);
597 if (n22loop != n_loop && n22loop->is_member(n_loop) &&
598 n23_loop == n_loop) {
599 Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
600 // Stuff new AddP in the loop preheader
601 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
602 Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
603 register_new_node(add2, n_ctrl);
604 _igvn.replace_node(n, add2);
605 return add2;
606 }
607 }
608 }
609
610 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
611 if (n2_loop != n_loop && n3_loop == n_loop) {
612 if (n->in(3)->Opcode() == Op_AddX) {
613 Node* V = n->in(3)->in(1);
614 Node* I = n->in(3)->in(2);
615 if (is_member(n_loop,get_ctrl(V))) {
616 } else {
617 Node *tmp = V; V = I; I = tmp;
618 }
619 if (!is_member(n_loop,get_ctrl(I))) {
620 Node* add1 = new AddPNode(n->in(1), n->in(2), I);
621 // Stuff new AddP in the loop preheader
622 register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
623 Node* add2 = new AddPNode(n->in(1), add1, V);
624 register_new_node(add2, n_ctrl);
625 _igvn.replace_node(n, add2);
626 return add2;
627 }
628 }
629 }
630 }
631
632 return nullptr;
633 }
634
635 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
636 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
637 assert(n->Opcode() == Op_AddI, "sanity");
638 Node * nn = nullptr;
639 Node * in1 = n->in(1);
640 Node * in2 = n->in(2);
641 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
642 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
643 if (loop_n->is_counted() &&
644 loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
645 Matcher::match_rule_supported(Op_MulAddVS2VI) &&
646 Matcher::match_rule_supported(Op_MulAddS2I)) {
647 Node* mul_in1 = in1->in(1);
648 Node* mul_in2 = in1->in(2);
649 Node* mul_in3 = in2->in(1);
650 Node* mul_in4 = in2->in(2);
651 if (mul_in1->Opcode() == Op_LoadS &&
652 mul_in2->Opcode() == Op_LoadS &&
653 mul_in3->Opcode() == Op_LoadS &&
654 mul_in4->Opcode() == Op_LoadS) {
655 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
656 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
657 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
658 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
659 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
660 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
661 // All nodes should be in the same counted loop.
662 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
663 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
664 Node* adr1 = mul_in1->in(MemNode::Address);
665 Node* adr2 = mul_in2->in(MemNode::Address);
666 Node* adr3 = mul_in3->in(MemNode::Address);
667 Node* adr4 = mul_in4->in(MemNode::Address);
668 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
669 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
670 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
671 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
672 register_new_node_with_ctrl_of(nn, n);
673 _igvn.replace_node(n, nn);
674 return nn;
675 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
676 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
677 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
678 register_new_node_with_ctrl_of(nn, n);
679 _igvn.replace_node(n, nn);
680 return nn;
681 }
682 }
683 }
684 }
685 }
686 }
687 return nn;
688 }
689
690 //------------------------------conditional_move-------------------------------
691 // Attempt to replace a Phi with a conditional move. We have some pretty
692 // strict profitability requirements. All Phis at the merge point must
693 // be converted, so we can remove the control flow. We need to limit the
694 // number of c-moves to a small handful. All code that was in the side-arms
695 // of the CFG diamond is now speculatively executed. This code has to be
696 // "cheap enough". We are pretty much limited to CFG diamonds that merge
697 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
698 Node *PhaseIdealLoop::conditional_move( Node *region ) {
699
700 assert(region->is_Region(), "sanity check");
701 if (region->req() != 3) return nullptr;
702
703 // Check for CFG diamond
704 Node *lp = region->in(1);
705 Node *rp = region->in(2);
706 if (!lp || !rp) return nullptr;
707 Node *lp_c = lp->in(0);
708 if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
709 IfNode *iff = lp_c->as_If();
710
711 // Check for ops pinned in an arm of the diamond.
712 // Can't remove the control flow in this case
713 if (lp->outcnt() > 1) return nullptr;
714 if (rp->outcnt() > 1) return nullptr;
715
716 IdealLoopTree* r_loop = get_loop(region);
717 assert(r_loop == get_loop(iff), "sanity");
718 // Always convert to CMOVE if all results are used only outside this loop.
719 bool used_inside_loop = (r_loop == _ltree_root);
720
721 // Check profitability
722 int cost = 0;
723 int phis = 0;
724 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
725 Node *out = region->fast_out(i);
726 if (!out->is_Phi()) continue; // Ignore other control edges, etc
727 phis++;
728 PhiNode* phi = out->as_Phi();
729 BasicType bt = phi->type()->basic_type();
730 switch (bt) {
731 case T_DOUBLE:
732 case T_FLOAT:
733 if (C->use_cmove()) {
734 continue; //TODO: maybe we want to add some cost
735 }
736 cost += Matcher::float_cmove_cost(); // Could be very expensive
737 break;
738 case T_LONG: {
739 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
740 }
741 case T_INT: // These all CMOV fine
742 case T_ADDRESS: { // (RawPtr)
743 cost++;
744 break;
745 }
746 case T_NARROWOOP: // Fall through
747 case T_OBJECT: { // Base oops are OK, but not derived oops
748 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
749 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
750 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
751 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
752 // have a Phi for the base here that we convert to a CMOVE all is well
753 // and good. But if the base is dead, we'll not make a CMOVE. Later
754 // the allocator will have to produce a base by creating a CMOVE of the
755 // relevant bases. This puts the allocator in the business of
756 // manufacturing expensive instructions, generally a bad plan.
757 // Just Say No to Conditionally-Moved Derived Pointers.
758 if (tp && tp->offset() != 0)
759 return nullptr;
760 cost++;
761 break;
762 }
763 default:
764 return nullptr; // In particular, can't do memory or I/O
765 }
766 // Add in cost any speculative ops
767 for (uint j = 1; j < region->req(); j++) {
768 Node *proj = region->in(j);
769 Node *inp = phi->in(j);
770 if (inp->isa_InlineType()) {
771 // TODO 8302217 This prevents PhiNode::push_inline_types_through
772 return nullptr;
773 }
774 if (get_ctrl(inp) == proj) { // Found local op
775 cost++;
776 // Check for a chain of dependent ops; these will all become
777 // speculative in a CMOV.
778 for (uint k = 1; k < inp->req(); k++)
779 if (get_ctrl(inp->in(k)) == proj)
780 cost += ConditionalMoveLimit; // Too much speculative goo
781 }
782 }
783 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
784 // This will likely Split-If, a higher-payoff operation.
785 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
786 Node* use = phi->fast_out(k);
787 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
788 cost += ConditionalMoveLimit;
789 // Is there a use inside the loop?
790 // Note: check only basic types since CMoveP is pinned.
791 if (!used_inside_loop && is_java_primitive(bt)) {
792 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
793 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
794 used_inside_loop = true;
795 }
796 }
797 }
798 }//for
799 Node* bol = iff->in(1);
800 assert(!bol->is_OpaqueInitializedAssertionPredicate(), "Initialized Assertion Predicates cannot form a diamond with Halt");
801 if (bol->is_OpaqueTemplateAssertionPredicate()) {
802 // Ignore Template Assertion Predicates with OpaqueTemplateAssertionPredicate nodes.
803 assert(assertion_predicate_has_loop_opaque_node(iff), "must find OpaqueLoop* nodes");
804 return nullptr;
805 }
806 assert(bol->Opcode() == Op_Bool, "Unexpected node");
807 int cmp_op = bol->in(1)->Opcode();
808 if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
809 return nullptr;
810 }
811 // It is expensive to generate flags from a float compare.
812 // Avoid duplicated float compare.
813 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
814
815 float infrequent_prob = PROB_UNLIKELY_MAG(3);
816 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
817 if (used_inside_loop) {
818 if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
819
820 // BlockLayoutByFrequency optimization moves infrequent branch
821 // from hot path. No point in CMOV'ing in such case (110 is used
822 // instead of 100 to take into account not exactness of float value).
823 if (BlockLayoutByFrequency) {
824 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
825 }
826 }
827 // Check for highly predictable branch. No point in CMOV'ing if
828 // we are going to predict accurately all the time.
829 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
830 //keep going
831 } else if (iff->_prob < infrequent_prob ||
832 iff->_prob > (1.0f - infrequent_prob))
833 return nullptr;
834
835 // --------------
836 // Now replace all Phis with CMOV's
837 Node *cmov_ctrl = iff->in(0);
838 uint flip = (lp->Opcode() == Op_IfTrue);
839 Node_List wq;
840 while (1) {
841 PhiNode* phi = nullptr;
842 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
843 Node *out = region->fast_out(i);
844 if (out->is_Phi()) {
845 phi = out->as_Phi();
846 break;
847 }
848 }
849 if (phi == nullptr || _igvn.type(phi) == Type::TOP) {
850 break;
851 }
852 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
853 // Move speculative ops
854 wq.push(phi);
855 while (wq.size() > 0) {
856 Node *n = wq.pop();
857 for (uint j = 1; j < n->req(); j++) {
858 Node* m = n->in(j);
859 if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
860 #ifndef PRODUCT
861 if (PrintOpto && VerifyLoopOptimizations) {
862 tty->print(" speculate: ");
863 m->dump();
864 }
865 #endif
866 set_ctrl(m, cmov_ctrl);
867 wq.push(m);
868 }
869 }
870 }
871 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
872 register_new_node( cmov, cmov_ctrl );
873 _igvn.replace_node( phi, cmov );
874 #ifndef PRODUCT
875 if (TraceLoopOpts) {
876 tty->print("CMOV ");
877 r_loop->dump_head();
878 if (Verbose) {
879 bol->in(1)->dump(1);
880 cmov->dump(1);
881 }
882 }
883 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
884 #endif
885 }
886
887 // The useless CFG diamond will fold up later; see the optimization in
888 // RegionNode::Ideal.
889 _igvn._worklist.push(region);
890
891 return iff->in(1);
892 }
893
894 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
895 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
896 Node* u = m->fast_out(i);
897 if (u->is_CFG()) {
898 if (u->is_NeverBranch()) {
899 u = u->as_NeverBranch()->proj_out(0);
900 enqueue_cfg_uses(u, wq);
901 } else {
902 wq.push(u);
903 }
904 }
905 }
906 }
907
908 // Try moving a store out of a loop, right before the loop
909 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
910 // Store has to be first in the loop body
911 IdealLoopTree *n_loop = get_loop(n_ctrl);
912 if (n->is_Store() && n_loop != _ltree_root &&
913 n_loop->is_loop() && n_loop->_head->is_Loop() &&
914 n->in(0) != nullptr) {
915 Node* address = n->in(MemNode::Address);
916 Node* value = n->in(MemNode::ValueIn);
917 Node* mem = n->in(MemNode::Memory);
918 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
919 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
920
921 // - address and value must be loop invariant
922 // - memory must be a memory Phi for the loop
923 // - Store must be the only store on this memory slice in the
924 // loop: if there's another store following this one then value
925 // written at iteration i by the second store could be overwritten
926 // at iteration i+n by the first store: it's not safe to move the
927 // first store out of the loop
928 // - nothing must observe the memory Phi: it guarantees no read
929 // before the store, we are also guaranteed the store post
930 // dominates the loop head (ignoring a possible early
931 // exit). Otherwise there would be extra Phi involved between the
932 // loop's Phi and the store.
933 // - there must be no early exit from the loop before the Store
934 // (such an exit most of the time would be an extra use of the
935 // memory Phi but sometimes is a bottom memory Phi that takes the
936 // store as input).
937
938 if (!n_loop->is_member(address_loop) &&
939 !n_loop->is_member(value_loop) &&
940 mem->is_Phi() && mem->in(0) == n_loop->_head &&
941 mem->outcnt() == 1 &&
942 mem->in(LoopNode::LoopBackControl) == n) {
943
944 assert(n_loop->_tail != nullptr, "need a tail");
945 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
946
947 // Verify that there's no early exit of the loop before the store.
948 bool ctrl_ok = false;
949 {
950 // Follow control from loop head until n, we exit the loop or
951 // we reach the tail
952 ResourceMark rm;
953 Unique_Node_List wq;
954 wq.push(n_loop->_head);
955
956 for (uint next = 0; next < wq.size(); ++next) {
957 Node *m = wq.at(next);
958 if (m == n->in(0)) {
959 ctrl_ok = true;
960 continue;
961 }
962 assert(!has_ctrl(m), "should be CFG");
963 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
964 ctrl_ok = false;
965 break;
966 }
967 enqueue_cfg_uses(m, wq);
968 if (wq.size() > 10) {
969 ctrl_ok = false;
970 break;
971 }
972 }
973 }
974 if (ctrl_ok) {
975 // move the Store
976 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
977 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
978 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
979 // Disconnect the phi now. An empty phi can confuse other
980 // optimizations in this pass of loop opts.
981 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
982 n_loop->_body.yank(mem);
983
984 set_ctrl_and_loop(n, n->in(0));
985
986 return n;
987 }
988 }
989 }
990 return nullptr;
991 }
992
993 // Try moving a store out of a loop, right after the loop
994 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
995 if (n->is_Store() && n->in(0) != nullptr) {
996 Node *n_ctrl = get_ctrl(n);
997 IdealLoopTree *n_loop = get_loop(n_ctrl);
998 // Store must be in a loop
999 if (n_loop != _ltree_root && !n_loop->_irreducible) {
1000 Node* address = n->in(MemNode::Address);
1001 Node* value = n->in(MemNode::ValueIn);
1002 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
1003 // address must be loop invariant
1004 if (!n_loop->is_member(address_loop)) {
1005 // Store must be last on this memory slice in the loop and
1006 // nothing in the loop must observe it
1007 Node* phi = nullptr;
1008 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1009 Node* u = n->fast_out(i);
1010 if (has_ctrl(u)) { // control use?
1011 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1012 if (!n_loop->is_member(u_loop)) {
1013 continue;
1014 }
1015 if (u->is_Phi() && u->in(0) == n_loop->_head) {
1016 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1017 // multiple phis on the same slice are possible
1018 if (phi != nullptr) {
1019 return;
1020 }
1021 phi = u;
1022 continue;
1023 }
1024 }
1025 return;
1026 }
1027 if (phi != nullptr) {
1028 // Nothing in the loop before the store (next iteration)
1029 // must observe the stored value
1030 bool mem_ok = true;
1031 {
1032 ResourceMark rm;
1033 Unique_Node_List wq;
1034 wq.push(phi);
1035 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1036 Node *m = wq.at(next);
1037 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1038 Node* u = m->fast_out(i);
1039 if (u->is_Store() || u->is_Phi()) {
1040 if (u != n) {
1041 wq.push(u);
1042 mem_ok = (wq.size() <= 10);
1043 }
1044 } else {
1045 mem_ok = false;
1046 break;
1047 }
1048 }
1049 }
1050 }
1051 if (mem_ok) {
1052 // Move the store out of the loop if the LCA of all
1053 // users (except for the phi) is outside the loop.
1054 Node* hook = new Node(1);
1055 hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1056 _igvn.rehash_node_delayed(phi);
1057 int count = phi->replace_edge(n, hook, &_igvn);
1058 assert(count > 0, "inconsistent phi");
1059
1060 // Compute latest point this store can go
1061 Node* lca = get_late_ctrl(n, get_ctrl(n));
1062 if (lca->is_OuterStripMinedLoop()) {
1063 lca = lca->in(LoopNode::EntryControl);
1064 }
1065 if (n_loop->is_member(get_loop(lca))) {
1066 // LCA is in the loop - bail out
1067 _igvn.replace_node(hook, n);
1068 return;
1069 }
1070 #ifdef ASSERT
1071 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1072 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1073 n_loop->_head->as_Loop()->verify_strip_mined(1);
1074 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1075 IdealLoopTree* outer_loop = get_loop(outer);
1076 assert(n_loop->_parent == outer_loop, "broken loop tree");
1077 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1078 }
1079 #endif
1080 lca = place_outside_loop(lca, n_loop);
1081 assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1082 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");
1083
1084 // Move store out of the loop
1085 _igvn.replace_node(hook, n->in(MemNode::Memory));
1086 _igvn.replace_input_of(n, 0, lca);
1087 set_ctrl_and_loop(n, lca);
1088
1089 // Disconnect the phi now. An empty phi can confuse other
1090 // optimizations in this pass of loop opts..
1091 if (phi->in(LoopNode::LoopBackControl) == phi) {
1092 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1093 n_loop->_body.yank(phi);
1094 }
1095 }
1096 }
1097 }
1098 }
1099 }
1100 }
1101
1102 // We can't use immutable memory for the flat array check because we are loading the mark word which is
1103 // mutable. Although the bits we are interested in are immutable (we check for markWord::unlocked_value),
1104 // we need to use raw memory to not break anti dependency analysis. Below code will attempt to still move
1105 // flat array checks out of loops, mainly to enable loop unswitching.
1106 void PhaseIdealLoop::move_flat_array_check_out_of_loop(Node* n) {
1107 // Skip checks for more than one array
1108 if (n->req() > 3) {
1109 return;
1110 }
1111 Node* mem = n->in(FlatArrayCheckNode::Memory);
1112 Node* array = n->in(FlatArrayCheckNode::ArrayOrKlass)->uncast();
1113 IdealLoopTree* check_loop = get_loop(get_ctrl(n));
1114 IdealLoopTree* ary_loop = get_loop(get_ctrl(array));
1115
1116 // Check if array is loop invariant
1117 if (!check_loop->is_member(ary_loop)) {
1118 // Walk up memory graph from the check until we leave the loop
1119 VectorSet wq;
1120 wq.set(mem->_idx);
1121 while (check_loop->is_member(get_loop(ctrl_or_self(mem)))) {
1122 if (mem->is_Phi()) {
1123 mem = mem->in(1);
1124 } else if (mem->is_MergeMem()) {
1125 mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
1126 } else if (mem->is_Proj()) {
1127 mem = mem->in(0);
1128 } else if (mem->is_MemBar() || mem->is_SafePoint()) {
1129 mem = mem->in(TypeFunc::Memory);
1130 } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
1131 mem = mem->in(MemNode::Memory);
1132 } else {
1133 #ifdef ASSERT
1134 mem->dump();
1135 #endif
1136 ShouldNotReachHere();
1137 }
1138 if (wq.test_set(mem->_idx)) {
1139 return;
1140 }
1141 }
1142 // Replace memory input and re-compute ctrl to move the check out of the loop
1143 _igvn.replace_input_of(n, 1, mem);
1144 set_ctrl_and_loop(n, get_early_ctrl(n));
1145 Node* bol = n->unique_out();
1146 set_ctrl_and_loop(bol, get_early_ctrl(bol));
1147 }
1148 }
1149
1150 // Split some nodes that take a counted loop phi as input at a counted
1151 // loop can cause vectorization of some expressions to fail
1152 bool PhaseIdealLoop::split_thru_phi_could_prevent_vectorization(Node* n, Node* n_blk) {
1153 if (!n_blk->is_CountedLoop()) {
1154 return false;
1155 }
1156
1157 int opcode = n->Opcode();
1158
1159 if (opcode != Op_AndI &&
1160 opcode != Op_MulI &&
1161 opcode != Op_RotateRight &&
1162 opcode != Op_RShiftI) {
1163 return false;
1164 }
1165
1166 return n->in(1) == n_blk->as_BaseCountedLoop()->phi();
1167 }
1168
1169 //------------------------------split_if_with_blocks_pre-----------------------
1170 // Do the real work in a non-recursive function. Data nodes want to be
1171 // cloned in the pre-order so they can feed each other nicely.
1172 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1173 // Cloning these guys is unlikely to win
1174 int n_op = n->Opcode();
1175 if (n_op == Op_MergeMem) {
1176 return n;
1177 }
1178 if (n->is_Proj()) {
1179 return n;
1180 }
1181
1182 if (n->isa_FlatArrayCheck()) {
1183 move_flat_array_check_out_of_loop(n);
1184 return n;
1185 }
1186
1187 // Do not clone-up CmpFXXX variations, as these are always
1188 // followed by a CmpI
1189 if (n->is_Cmp()) {
1190 return n;
1191 }
1192 // Attempt to use a conditional move instead of a phi/branch
1193 if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1194 Node *cmov = conditional_move( n );
1195 if (cmov) {
1196 return cmov;
1197 }
1198 }
1199 if (n->is_CFG() || n->is_LoadStore()) {
1200 return n;
1201 }
1202 if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1203 if (!C->major_progress()) { // If chance of no more loop opts...
1204 _igvn._worklist.push(n); // maybe we'll remove them
1205 }
1206 return n;
1207 }
1208
1209 if (n->is_Con()) {
1210 return n; // No cloning for Con nodes
1211 }
1212
1213 Node *n_ctrl = get_ctrl(n);
1214 if (!n_ctrl) {
1215 return n; // Dead node
1216 }
1217
1218 Node* res = try_move_store_before_loop(n, n_ctrl);
1219 if (res != nullptr) {
1220 return n;
1221 }
1222
1223 // Attempt to remix address expressions for loop invariants
1224 Node *m = remix_address_expressions( n );
1225 if( m ) return m;
1226
1227 if (n_op == Op_AddI) {
1228 Node *nn = convert_add_to_muladd( n );
1229 if ( nn ) return nn;
1230 }
1231
1232 if (n->is_ConstraintCast()) {
1233 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1234 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1235 // Node control inputs don't necessarily agree with loop control info (due to
1236 // transformations happened in between), thus additional dominance check is needed
1237 // to keep loop info valid.
1238 if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1239 _igvn.replace_node(n, dom_cast);
1240 return dom_cast;
1241 }
1242 }
1243
1244 // Determine if the Node has inputs from some local Phi.
1245 // Returns the block to clone thru.
1246 Node *n_blk = has_local_phi_input( n );
1247 if( !n_blk ) return n;
1248
1249 // Do not clone the trip counter through on a CountedLoop
1250 // (messes up the canonical shape).
1251 if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1252 (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1253 return n;
1254 }
1255 // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1256 if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1257 n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1258 return n;
1259 }
1260
1261 if (split_thru_phi_could_prevent_vectorization(n, n_blk)) {
1262 return n;
1263 }
1264
1265 // Check for having no control input; not pinned. Allow
1266 // dominating control.
1267 if (n->in(0)) {
1268 Node *dom = idom(n_blk);
1269 if (dom_lca(n->in(0), dom) != n->in(0)) {
1270 return n;
1271 }
1272 }
1273 // Policy: when is it profitable. You must get more wins than
1274 // policy before it is considered profitable. Policy is usually 0,
1275 // so 1 win is considered profitable. Big merges will require big
1276 // cloning, so get a larger policy.
1277 int policy = n_blk->req() >> 2;
1278
1279 // If the loop is a candidate for range check elimination,
1280 // delay splitting through it's phi until a later loop optimization
1281 if (n_blk->is_BaseCountedLoop()) {
1282 IdealLoopTree *lp = get_loop(n_blk);
1283 if (lp && lp->_rce_candidate) {
1284 return n;
1285 }
1286 }
1287
1288 if (must_throttle_split_if()) return n;
1289
1290 // Split 'n' through the merge point if it is profitable
1291 Node *phi = split_thru_phi( n, n_blk, policy );
1292 if (!phi) return n;
1293
1294 // Found a Phi to split thru!
1295 // Replace 'n' with the new phi
1296 _igvn.replace_node( n, phi );
1297 // Moved a load around the loop, 'en-registering' something.
1298 if (n_blk->is_Loop() && n->is_Load() &&
1299 !phi->in(LoopNode::LoopBackControl)->is_Load())
1300 C->set_major_progress();
1301
1302 return phi;
1303 }
1304
1305 static bool merge_point_too_heavy(Compile* C, Node* region) {
1306 // Bail out if the region and its phis have too many users.
1307 int weight = 0;
1308 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1309 weight += region->fast_out(i)->outcnt();
1310 }
1311 int nodes_left = C->max_node_limit() - C->live_nodes();
1312 if (weight * 8 > nodes_left) {
1313 if (PrintOpto) {
1314 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1315 }
1316 return true;
1317 } else {
1318 return false;
1319 }
1320 }
1321
1322 static bool merge_point_safe(Node* region) {
1323 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1324 // having a PhiNode input. This sidesteps the dangerous case where the split
1325 // ConvI2LNode may become TOP if the input Value() does not
1326 // overlap the ConvI2L range, leaving a node which may not dominate its
1327 // uses.
1328 // A better fix for this problem can be found in the BugTraq entry, but
1329 // expediency for Mantis demands this hack.
1330 #ifdef _LP64
1331 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1332 Node* n = region->fast_out(i);
1333 if (n->is_Phi()) {
1334 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1335 Node* m = n->fast_out(j);
1336 if (m->Opcode() == Op_ConvI2L)
1337 return false;
1338 if (m->is_CastII()) {
1339 return false;
1340 }
1341 }
1342 }
1343 }
1344 #endif
1345 return true;
1346 }
1347
1348
1349 //------------------------------place_outside_loop---------------------------------
1350 // Place some computation outside of this loop on the path to the use passed as argument
1351 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1352 Node* head = loop->_head;
1353 assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1354 if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1355 loop = loop->_parent;
1356 assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1357 }
1358
1359 // Pick control right outside the loop
1360 for (;;) {
1361 Node* dom = idom(useblock);
1362 if (loop->is_member(get_loop(dom))) {
1363 break;
1364 }
1365 useblock = dom;
1366 }
1367 assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1368 return useblock;
1369 }
1370
1371
1372 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1373 if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1374 return false;
1375 }
1376 if (!n->in(0)->is_Region()) {
1377 return false;
1378 }
1379
1380 Node* region = n->in(0);
1381 Node* dom = idom(region);
1382 if (!dom->is_If() || !n->as_If()->same_condition(dom, &_igvn)) {
1383 return false;
1384 }
1385 IfNode* dom_if = dom->as_If();
1386 Node* proj_true = dom_if->proj_out(1);
1387 Node* proj_false = dom_if->proj_out(0);
1388
1389 for (uint i = 1; i < region->req(); i++) {
1390 if (is_dominator(proj_true, region->in(i))) {
1391 continue;
1392 }
1393 if (is_dominator(proj_false, region->in(i))) {
1394 continue;
1395 }
1396 return false;
1397 }
1398
1399 return true;
1400 }
1401
1402
1403 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1404 if (must_throttle_split_if()) {
1405 return false;
1406 }
1407
1408 // Do not do 'split-if' if irreducible loops are present.
1409 if (_has_irreducible_loops) {
1410 return false;
1411 }
1412
1413 if (merge_point_too_heavy(C, n_ctrl)) {
1414 return false;
1415 }
1416
1417 // Do not do 'split-if' if some paths are dead. First do dead code
1418 // elimination and then see if its still profitable.
1419 for (uint i = 1; i < n_ctrl->req(); i++) {
1420 if (n_ctrl->in(i) == C->top()) {
1421 return false;
1422 }
1423 }
1424
1425 // If trying to do a 'Split-If' at the loop head, it is only
1426 // profitable if the cmp folds up on BOTH paths. Otherwise we
1427 // risk peeling a loop forever.
1428
1429 // CNC - Disabled for now. Requires careful handling of loop
1430 // body selection for the cloned code. Also, make sure we check
1431 // for any input path not being in the same loop as n_ctrl. For
1432 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1433 // because the alternative loop entry points won't be converted
1434 // into LoopNodes.
1435 IdealLoopTree *n_loop = get_loop(n_ctrl);
1436 for (uint j = 1; j < n_ctrl->req(); j++) {
1437 if (get_loop(n_ctrl->in(j)) != n_loop) {
1438 return false;
1439 }
1440 }
1441
1442 // Check for safety of the merge point.
1443 if (!merge_point_safe(n_ctrl)) {
1444 return false;
1445 }
1446
1447 return true;
1448 }
1449
1450 // Detect if the node is the inner strip-mined loop
1451 // Return: null if it's not the case, or the exit of outer strip-mined loop
1452 static Node* is_inner_of_stripmined_loop(const Node* out) {
1453 Node* out_le = nullptr;
1454
1455 if (out->is_CountedLoopEnd()) {
1456 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1457
1458 if (loop != nullptr && loop->is_strip_mined()) {
1459 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1460 }
1461 }
1462
1463 return out_le;
1464 }
1465
1466 bool PhaseIdealLoop::flat_array_element_type_check(Node *n) {
1467 // If the CmpP is a subtype check for a value that has just been
1468 // loaded from an array, the subtype check guarantees the value
1469 // can't be stored in a flat array and the load of the value
1470 // happens with a flat array check then: push the type check
1471 // through the phi of the flat array check. This needs special
1472 // logic because the subtype check's input is not a phi but a
1473 // LoadKlass that must first be cloned through the phi.
1474 if (n->Opcode() != Op_CmpP) {
1475 return false;
1476 }
1477
1478 Node* klassptr = n->in(1);
1479 Node* klasscon = n->in(2);
1480
1481 if (klassptr->is_DecodeNarrowPtr()) {
1482 klassptr = klassptr->in(1);
1483 }
1484
1485 if (klassptr->Opcode() != Op_LoadKlass && klassptr->Opcode() != Op_LoadNKlass) {
1486 return false;
1487 }
1488
1489 if (!klasscon->is_Con()) {
1490 return false;
1491 }
1492
1493 Node* addr = klassptr->in(MemNode::Address);
1494
1495 if (!addr->is_AddP()) {
1496 return false;
1497 }
1498
1499 intptr_t offset;
1500 Node* obj = AddPNode::Ideal_base_and_offset(addr, &_igvn, offset);
1501
1502 if (obj == nullptr) {
1503 return false;
1504 }
1505
1506 assert(obj != nullptr && addr->in(AddPNode::Base) == addr->in(AddPNode::Address), "malformed AddP?");
1507 if (obj->Opcode() == Op_CastPP) {
1508 obj = obj->in(1);
1509 }
1510
1511 if (!obj->is_Phi()) {
1512 return false;
1513 }
1514
1515 Node* region = obj->in(0);
1516
1517 Node* phi = PhiNode::make_blank(region, n->in(1));
1518 for (uint i = 1; i < region->req(); i++) {
1519 Node* in = obj->in(i);
1520 Node* ctrl = region->in(i);
1521 if (addr->in(AddPNode::Base) != obj) {
1522 Node* cast = addr->in(AddPNode::Base);
1523 assert(cast->Opcode() == Op_CastPP && cast->in(0) != nullptr, "inconsistent subgraph");
1524 Node* cast_clone = cast->clone();
1525 cast_clone->set_req(0, ctrl);
1526 cast_clone->set_req(1, in);
1527 register_new_node(cast_clone, ctrl);
1528 const Type* tcast = cast_clone->Value(&_igvn);
1529 _igvn.set_type(cast_clone, tcast);
1530 cast_clone->as_Type()->set_type(tcast);
1531 in = cast_clone;
1532 }
1533 Node* addr_clone = addr->clone();
1534 addr_clone->set_req(AddPNode::Base, in);
1535 addr_clone->set_req(AddPNode::Address, in);
1536 register_new_node(addr_clone, ctrl);
1537 _igvn.set_type(addr_clone, addr_clone->Value(&_igvn));
1538 Node* klassptr_clone = klassptr->clone();
1539 klassptr_clone->set_req(2, addr_clone);
1540 register_new_node(klassptr_clone, ctrl);
1541 _igvn.set_type(klassptr_clone, klassptr_clone->Value(&_igvn));
1542 if (klassptr != n->in(1)) {
1543 Node* decode = n->in(1);
1544 assert(decode->is_DecodeNarrowPtr(), "inconsistent subgraph");
1545 Node* decode_clone = decode->clone();
1546 decode_clone->set_req(1, klassptr_clone);
1547 register_new_node(decode_clone, ctrl);
1548 _igvn.set_type(decode_clone, decode_clone->Value(&_igvn));
1549 klassptr_clone = decode_clone;
1550 }
1551 phi->set_req(i, klassptr_clone);
1552 }
1553 register_new_node(phi, region);
1554 Node* orig = n->in(1);
1555 _igvn.replace_input_of(n, 1, phi);
1556 split_if_with_blocks_post(n);
1557 if (n->outcnt() != 0) {
1558 _igvn.replace_input_of(n, 1, orig);
1559 _igvn.remove_dead_node(phi);
1560 }
1561 return true;
1562 }
1563
1564 //------------------------------split_if_with_blocks_post----------------------
1565 // Do the real work in a non-recursive function. CFG hackery wants to be
1566 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1567 // info.
1568 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1569
1570 if (flat_array_element_type_check(n)) {
1571 return;
1572 }
1573
1574 // Cloning Cmp through Phi's involves the split-if transform.
1575 // FastLock is not used by an If
1576 if (n->is_Cmp() && !n->is_FastLock()) {
1577 Node *n_ctrl = get_ctrl(n);
1578 // Determine if the Node has inputs from some local Phi.
1579 // Returns the block to clone thru.
1580 Node *n_blk = has_local_phi_input(n);
1581 if (n_blk != n_ctrl) {
1582 return;
1583 }
1584
1585 if (!can_split_if(n_ctrl)) {
1586 return;
1587 }
1588
1589 if (n->outcnt() != 1) {
1590 return; // Multiple bool's from 1 compare?
1591 }
1592 Node *bol = n->unique_out();
1593 assert(bol->is_Bool(), "expect a bool here");
1594 if (bol->outcnt() != 1) {
1595 return;// Multiple branches from 1 compare?
1596 }
1597 Node *iff = bol->unique_out();
1598
1599 // Check some safety conditions
1600 if (iff->is_If()) { // Classic split-if?
1601 if (iff->in(0) != n_ctrl) {
1602 return; // Compare must be in same blk as if
1603 }
1604 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1605 // Can't split CMove with different control.
1606 if (get_ctrl(iff) != n_ctrl) {
1607 return;
1608 }
1609 if (get_ctrl(iff->in(2)) == n_ctrl ||
1610 get_ctrl(iff->in(3)) == n_ctrl) {
1611 return; // Inputs not yet split-up
1612 }
1613 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1614 return; // Loop-invar test gates loop-varying CMOVE
1615 }
1616 } else {
1617 return; // some other kind of node, such as an Allocate
1618 }
1619
1620 // When is split-if profitable? Every 'win' on means some control flow
1621 // goes dead, so it's almost always a win.
1622 int policy = 0;
1623 // Split compare 'n' through the merge point if it is profitable
1624 Node *phi = split_thru_phi( n, n_ctrl, policy);
1625 if (!phi) {
1626 return;
1627 }
1628
1629 // Found a Phi to split thru!
1630 // Replace 'n' with the new phi
1631 _igvn.replace_node(n, phi);
1632
1633 // Now split the bool up thru the phi
1634 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1635 guarantee(bolphi != nullptr, "null boolean phi node");
1636
1637 _igvn.replace_node(bol, bolphi);
1638 assert(iff->in(1) == bolphi, "");
1639
1640 if (bolphi->Value(&_igvn)->singleton()) {
1641 return;
1642 }
1643
1644 // Conditional-move? Must split up now
1645 if (!iff->is_If()) {
1646 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1647 _igvn.replace_node(iff, cmovphi);
1648 return;
1649 }
1650
1651 // Now split the IF
1652 C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1653 if ((PrintOpto && VerifyLoopOptimizations) || 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
1720 try_move_store_after_loop(n);
1721
1722 // Remove multiple allocations of the same inline type
1723 if (n->is_InlineType()) {
1724 n->as_InlineType()->remove_redundant_allocations(this);
1725 }
1726 }
1727
1728 // Transform:
1729 //
1730 // if (some_condition) {
1731 // // body 1
1732 // } else {
1733 // // body 2
1734 // }
1735 // if (some_condition) {
1736 // // body 3
1737 // } else {
1738 // // body 4
1739 // }
1740 //
1741 // into:
1742 //
1743 //
1744 // if (some_condition) {
1745 // // body 1
1746 // // body 3
1747 // } else {
1748 // // body 2
1749 // // body 4
1750 // }
1751 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1752 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1753 Node *n_ctrl = n->in(0);
1754 IfNode* dom_if = idom(n_ctrl)->as_If();
1755 if (n->in(1) != dom_if->in(1)) {
1756 assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1757 (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1758 dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1759 _igvn.replace_input_of(n, 1, dom_if->in(1));
1760 }
1761 ProjNode* dom_proj_true = dom_if->proj_out(1);
1762 ProjNode* dom_proj_false = dom_if->proj_out(0);
1763
1764 // Now split the IF
1765 RegionNode* new_false_region;
1766 RegionNode* new_true_region;
1767 do_split_if(n, &new_false_region, &new_true_region);
1768 assert(new_false_region->req() == new_true_region->req(), "");
1769 #ifdef ASSERT
1770 for (uint i = 1; i < new_false_region->req(); ++i) {
1771 assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1772 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");
1773 }
1774 #endif
1775 assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1776
1777 // We now have:
1778 // if (some_condition) {
1779 // // body 1
1780 // if (some_condition) {
1781 // body3: // new_true_region
1782 // // body3
1783 // } else {
1784 // goto body4;
1785 // }
1786 // } else {
1787 // // body 2
1788 // if (some_condition) {
1789 // goto body3;
1790 // } else {
1791 // body4: // new_false_region
1792 // // body4;
1793 // }
1794 // }
1795 //
1796
1797 // clone pinned nodes thru the resulting regions
1798 push_pinned_nodes_thru_region(dom_if, new_true_region);
1799 push_pinned_nodes_thru_region(dom_if, new_false_region);
1800
1801 // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1802 // 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
1803 // unrelated control dependency.
1804 for (uint i = 1; i < new_false_region->req(); i++) {
1805 if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1806 dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1807 } else {
1808 assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1809 dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1810 }
1811 }
1812 return true;
1813 }
1814 return false;
1815 }
1816
1817 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1818 for (DUIterator i = region->outs(); region->has_out(i); i++) {
1819 Node* u = region->out(i);
1820 if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1821 continue;
1822 }
1823 assert(u->in(0) == region, "not a control dependent node?");
1824 uint j = 1;
1825 for (; j < u->req(); ++j) {
1826 Node* in = u->in(j);
1827 if (!is_dominator(ctrl_or_self(in), dom_if)) {
1828 break;
1829 }
1830 }
1831 if (j == u->req()) {
1832 Node *phi = PhiNode::make_blank(region, u);
1833 for (uint k = 1; k < region->req(); ++k) {
1834 Node* clone = u->clone();
1835 clone->set_req(0, region->in(k));
1836 register_new_node(clone, region->in(k));
1837 phi->init_req(k, clone);
1838 }
1839 register_new_node(phi, region);
1840 _igvn.replace_node(u, phi);
1841 --i;
1842 }
1843 }
1844 }
1845
1846 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1847 if (!dom->is_CountedLoopEnd()) {
1848 return true;
1849 }
1850 CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1851 CountedLoopNode* cl = le->loopnode();
1852 if (cl == nullptr) {
1853 return true;
1854 }
1855 if (!cl->is_main_loop()) {
1856 return true;
1857 }
1858 if (cl->is_canonical_loop_entry() == nullptr) {
1859 return true;
1860 }
1861 // Further unrolling is possible so loop exit condition might change
1862 return false;
1863 }
1864
1865 // See if a shared loop-varying computation has no loop-varying uses.
1866 // Happens if something is only used for JVM state in uncommon trap exits,
1867 // like various versions of induction variable+offset. Clone the
1868 // computation per usage to allow it to sink out of the loop.
1869 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1870 if (has_ctrl(n) &&
1871 !n->is_Phi() &&
1872 !n->is_Bool() &&
1873 !n->is_Proj() &&
1874 !n->is_MergeMem() &&
1875 !n->is_CMove() &&
1876 !n->is_OpaqueNotNull() &&
1877 !n->is_OpaqueInitializedAssertionPredicate() &&
1878 !n->is_OpaqueTemplateAssertionPredicate() &&
1879 !n->is_Type()) {
1880 Node *n_ctrl = get_ctrl(n);
1881 IdealLoopTree *n_loop = get_loop(n_ctrl);
1882
1883 if (n->in(0) != nullptr) {
1884 IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1885 if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1886 // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1887 // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1888 // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1889 Node* maybe_pinned_n = n;
1890 Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1891 if (n->depends_only_on_test()) {
1892 Node* pinned_clone = n->pin_array_access_node();
1893 if (pinned_clone != nullptr) {
1894 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1895 // range check for that access. If that condition is replaced by an identical dominating one, then an
1896 // unpinned load would risk floating above its range check.
1897 register_new_node(pinned_clone, n_ctrl);
1898 maybe_pinned_n = pinned_clone;
1899 _igvn.replace_node(n, pinned_clone);
1900 }
1901 }
1902 _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1903 }
1904 }
1905 if (n_loop != _ltree_root && n->outcnt() > 1) {
1906 // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1907 // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1908 Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1909 if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1910 ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1911 assert(!n->is_Store() && !n->is_LoadStore(), "no node with a side effect");
1912 Node* outer_loop_clone = nullptr;
1913 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1914 Node* u = n->last_out(j); // Clone private computation per use
1915 _igvn.rehash_node_delayed(u);
1916 Node* x = nullptr;
1917 if (n->depends_only_on_test()) {
1918 // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1919 // range check for that access. If that condition is replaced by an identical dominating one, then an
1920 // unpinned load would risk floating above its range check.
1921 x = n->pin_array_access_node();
1922 }
1923 if (x == nullptr) {
1924 x = n->clone();
1925 }
1926 Node* x_ctrl = nullptr;
1927 if (u->is_Phi()) {
1928 // Replace all uses of normal nodes. Replace Phi uses
1929 // individually, so the separate Nodes can sink down
1930 // different paths.
1931 uint k = 1;
1932 while (u->in(k) != n) k++;
1933 u->set_req(k, x);
1934 // x goes next to Phi input path
1935 x_ctrl = u->in(0)->in(k);
1936 // Find control for 'x' next to use but not inside inner loops.
1937 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1938 --j;
1939 } else { // Normal use
1940 if (has_ctrl(u)) {
1941 x_ctrl = get_ctrl(u);
1942 } else {
1943 x_ctrl = u->in(0);
1944 }
1945 // Find control for 'x' next to use but not inside inner loops.
1946 x_ctrl = place_outside_loop(x_ctrl, n_loop);
1947 // Replace all uses
1948 if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1949 // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1950 // anymore now that we're going to pin n as well
1951 _igvn.replace_node(u, x);
1952 --j;
1953 } else {
1954 int nb = u->replace_edge(n, x, &_igvn);
1955 j -= nb;
1956 }
1957 }
1958
1959 if (n->is_Load()) {
1960 // For loads, add a control edge to a CFG node outside of the loop
1961 // to force them to not combine and return back inside the loop
1962 // during GVN optimization (4641526).
1963 assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1964
1965 IdealLoopTree* x_loop = get_loop(x_ctrl);
1966 Node* x_head = x_loop->_head;
1967 if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1968 // Do not add duplicate LoadNodes to the outer strip mined loop
1969 if (outer_loop_clone != nullptr) {
1970 _igvn.replace_node(x, outer_loop_clone);
1971 continue;
1972 }
1973 outer_loop_clone = x;
1974 }
1975 x->set_req(0, x_ctrl);
1976 } else if (n->in(0) != nullptr){
1977 x->set_req(0, x_ctrl);
1978 }
1979 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1980 assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1981 register_new_node(x, x_ctrl);
1982
1983 // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
1984 // All AddP nodes must keep the same base after sinking so:
1985 // 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,
1986 // their bases remain the same.
1987 // (see 2- below)
1988 assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1989 x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1990 !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1991 if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
1992 !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1993 assert(!x->is_Load(), "load should be pinned");
1994 // Use a cast node to pin clone out of loop
1995 Node* cast = nullptr;
1996 for (uint k = 0; k < x->req(); k++) {
1997 Node* in = x->in(k);
1998 if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
1999 const Type* in_t = _igvn.type(in);
2000 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
2001 ConstraintCastNode::UnconditionalDependency, nullptr);
2002 }
2003 if (cast != nullptr) {
2004 Node* prev = _igvn.hash_find_insert(cast);
2005 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
2006 cast->destruct(&_igvn);
2007 cast = prev;
2008 } else {
2009 register_new_node(cast, x_ctrl);
2010 }
2011 x->replace_edge(in, cast);
2012 // Chain of AddP nodes:
2013 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
2014 if (x->is_AddP() && k == AddPNode::Base) {
2015 update_addp_chain_base(x, n->in(AddPNode::Base), cast);
2016 }
2017 break;
2018 }
2019 }
2020 assert(cast != nullptr, "must have added a cast to pin the node");
2021 }
2022 }
2023 _igvn.remove_dead_node(n);
2024 }
2025 _dom_lca_tags_round = 0;
2026 }
2027 }
2028 }
2029
2030 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
2031 ResourceMark rm;
2032 Node_List wq;
2033 wq.push(x);
2034 while (wq.size() != 0) {
2035 Node* n = wq.pop();
2036 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2037 Node* u = n->fast_out(i);
2038 if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
2039 _igvn.replace_input_of(u, AddPNode::Base, new_base);
2040 wq.push(u);
2041 }
2042 }
2043 }
2044 }
2045
2046 // Compute the early control of a node by following its inputs until we reach
2047 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
2048 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
2049 Node* early_ctrl = nullptr;
2050 ResourceMark rm;
2051 Unique_Node_List wq;
2052 wq.push(n);
2053 for (uint i = 0; i < wq.size(); i++) {
2054 Node* m = wq.at(i);
2055 Node* c = nullptr;
2056 if (m->is_CFG()) {
2057 c = m;
2058 } else if (m->pinned()) {
2059 c = m->in(0);
2060 } else {
2061 for (uint j = 0; j < m->req(); j++) {
2062 Node* in = m->in(j);
2063 if (in != nullptr) {
2064 wq.push(in);
2065 }
2066 }
2067 }
2068 if (c != nullptr) {
2069 assert(is_dominator(c, n_ctrl), "control input must dominate current control");
2070 if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
2071 early_ctrl = c;
2072 }
2073 }
2074 }
2075 assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
2076 return early_ctrl;
2077 }
2078
2079 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
2080 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2081 Node* u = n->fast_out(i);
2082 if (u->is_Opaque1()) {
2083 return false; // Found loop limit, bugfix for 4677003
2084 }
2085 // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
2086 // get_late_ctrl_with_anti_dep() use their own tag
2087 _dom_lca_tags_round++;
2088 assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
2089
2090 if (u->is_Phi()) {
2091 for (uint j = 1; j < u->req(); ++j) {
2092 if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
2093 return false;
2094 }
2095 }
2096 } else {
2097 Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
2098 if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
2099 return false;
2100 }
2101 }
2102 }
2103 return true;
2104 }
2105
2106 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
2107 if (n->is_Load()) {
2108 ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
2109 }
2110 IdealLoopTree *u_loop = get_loop(ctrl);
2111 if (u_loop == n_loop) {
2112 return false; // Found loop-varying use
2113 }
2114 if (n_loop->is_member(u_loop)) {
2115 return false; // Found use in inner loop
2116 }
2117 // 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
2118 // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
2119 // test of the pre loop above the point in the graph where it's pinned.
2120 if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
2121 CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
2122 if (is_dominator(pre_loop->loopexit(), ctrl)) {
2123 return false;
2124 }
2125 }
2126 return true;
2127 }
2128
2129 //------------------------------split_if_with_blocks---------------------------
2130 // Check for aggressive application of 'split-if' optimization,
2131 // using basic block level info.
2132 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
2133 Node* root = C->root();
2134 visited.set(root->_idx); // first, mark root as visited
2135 // Do pre-visit work for root
2136 Node* n = split_if_with_blocks_pre(root);
2137 uint cnt = n->outcnt();
2138 uint i = 0;
2139
2140 while (true) {
2141 // Visit all children
2142 if (i < cnt) {
2143 Node* use = n->raw_out(i);
2144 ++i;
2145 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
2146 // Now do pre-visit work for this use
2147 use = split_if_with_blocks_pre(use);
2148 nstack.push(n, i); // Save parent and next use's index.
2149 n = use; // Process all children of current use.
2150 cnt = use->outcnt();
2151 i = 0;
2152 }
2153 }
2154 else {
2155 // All of n's children have been processed, complete post-processing.
2156 if (cnt != 0 && !n->is_Con()) {
2157 assert(has_node(n), "no dead nodes");
2158 split_if_with_blocks_post(n);
2159 }
2160 if (must_throttle_split_if()) {
2161 nstack.clear();
2162 }
2163 if (nstack.is_empty()) {
2164 // Finished all nodes on stack.
2165 break;
2166 }
2167 // Get saved parent node and next use's index. Visit the rest of uses.
2168 n = nstack.node();
2169 cnt = n->outcnt();
2170 i = nstack.index();
2171 nstack.pop();
2172 }
2173 }
2174 }
2175
2176
2177 //=============================================================================
2178 //
2179 // C L O N E A L O O P B O D Y
2180 //
2181
2182 //------------------------------clone_iff--------------------------------------
2183 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2184 // "Nearly" because all Nodes have been cloned from the original in the loop,
2185 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2186 // through the Phi recursively, and return a Bool.
2187 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2188
2189 // Convert this Phi into a Phi merging Bools
2190 uint i;
2191 for (i = 1; i < phi->req(); i++) {
2192 Node* b = phi->in(i);
2193 if (b->is_Phi()) {
2194 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2195 } else {
2196 assert(b->is_Bool() || b->is_OpaqueNotNull() || b->is_OpaqueInitializedAssertionPredicate(),
2197 "bool, non-null check with OpaqueNotNull or Initialized Assertion Predicate with its Opaque node");
2198 }
2199 }
2200 Node* n = phi->in(1);
2201 Node* sample_opaque = nullptr;
2202 Node *sample_bool = nullptr;
2203 if (n->is_OpaqueNotNull() || n->is_OpaqueInitializedAssertionPredicate()) {
2204 sample_opaque = n;
2205 sample_bool = n->in(1);
2206 assert(sample_bool->is_Bool(), "wrong type");
2207 } else {
2208 sample_bool = n;
2209 }
2210 Node* sample_cmp = sample_bool->in(1);
2211 const Type* t = Type::TOP;
2212 const TypePtr* at = nullptr;
2213 if (sample_cmp->is_FlatArrayCheck()) {
2214 // Left input of a FlatArrayCheckNode is memory, set the (adr) type of the phi accordingly
2215 assert(sample_cmp->in(1)->bottom_type() == Type::MEMORY, "unexpected input type");
2216 t = Type::MEMORY;
2217 at = TypeRawPtr::BOTTOM;
2218 }
2219
2220 // Make Phis to merge the Cmp's inputs.
2221 PhiNode *phi1 = new PhiNode(phi->in(0), t, at);
2222 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2223 for (i = 1; i < phi->req(); i++) {
2224 Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2225 Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2226 phi1->set_req(i, n1);
2227 phi2->set_req(i, n2);
2228 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2229 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2230 }
2231 // See if these Phis have been made before.
2232 // Register with optimizer
2233 Node *hit1 = _igvn.hash_find_insert(phi1);
2234 if (hit1) { // Hit, toss just made Phi
2235 _igvn.remove_dead_node(phi1); // Remove new phi
2236 assert(hit1->is_Phi(), "" );
2237 phi1 = (PhiNode*)hit1; // Use existing phi
2238 } else { // Miss
2239 _igvn.register_new_node_with_optimizer(phi1);
2240 }
2241 Node *hit2 = _igvn.hash_find_insert(phi2);
2242 if (hit2) { // Hit, toss just made Phi
2243 _igvn.remove_dead_node(phi2); // Remove new phi
2244 assert(hit2->is_Phi(), "" );
2245 phi2 = (PhiNode*)hit2; // Use existing phi
2246 } else { // Miss
2247 _igvn.register_new_node_with_optimizer(phi2);
2248 }
2249 // Register Phis with loop/block info
2250 set_ctrl(phi1, phi->in(0));
2251 set_ctrl(phi2, phi->in(0));
2252 // Make a new Cmp
2253 Node *cmp = sample_cmp->clone();
2254 cmp->set_req(1, phi1);
2255 cmp->set_req(2, phi2);
2256 _igvn.register_new_node_with_optimizer(cmp);
2257 set_ctrl(cmp, phi->in(0));
2258
2259 // Make a new Bool
2260 Node *b = sample_bool->clone();
2261 b->set_req(1,cmp);
2262 _igvn.register_new_node_with_optimizer(b);
2263 set_ctrl(b, phi->in(0));
2264
2265 if (sample_opaque != nullptr) {
2266 Node* opaque = sample_opaque->clone();
2267 opaque->set_req(1, b);
2268 _igvn.register_new_node_with_optimizer(opaque);
2269 set_ctrl(opaque, phi->in(0));
2270 return opaque;
2271 }
2272
2273 assert(b->is_Bool(), "");
2274 return b;
2275 }
2276
2277 //------------------------------clone_bool-------------------------------------
2278 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2279 // "Nearly" because all Nodes have been cloned from the original in the loop,
2280 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
2281 // through the Phi recursively, and return a Bool.
2282 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2283 uint i;
2284 // Convert this Phi into a Phi merging Bools
2285 for( i = 1; i < phi->req(); i++ ) {
2286 Node *b = phi->in(i);
2287 if( b->is_Phi() ) {
2288 _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2289 } else {
2290 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2291 }
2292 }
2293
2294 Node *sample_cmp = phi->in(1);
2295
2296 // Make Phis to merge the Cmp's inputs.
2297 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2298 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2299 for( uint j = 1; j < phi->req(); j++ ) {
2300 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2301 Node *n1, *n2;
2302 if( cmp_top->is_Cmp() ) {
2303 n1 = cmp_top->in(1);
2304 n2 = cmp_top->in(2);
2305 } else {
2306 n1 = n2 = cmp_top;
2307 }
2308 phi1->set_req( j, n1 );
2309 phi2->set_req( j, n2 );
2310 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2311 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2312 }
2313
2314 // See if these Phis have been made before.
2315 // Register with optimizer
2316 Node *hit1 = _igvn.hash_find_insert(phi1);
2317 if( hit1 ) { // Hit, toss just made Phi
2318 _igvn.remove_dead_node(phi1); // Remove new phi
2319 assert( hit1->is_Phi(), "" );
2320 phi1 = (PhiNode*)hit1; // Use existing phi
2321 } else { // Miss
2322 _igvn.register_new_node_with_optimizer(phi1);
2323 }
2324 Node *hit2 = _igvn.hash_find_insert(phi2);
2325 if( hit2 ) { // Hit, toss just made Phi
2326 _igvn.remove_dead_node(phi2); // Remove new phi
2327 assert( hit2->is_Phi(), "" );
2328 phi2 = (PhiNode*)hit2; // Use existing phi
2329 } else { // Miss
2330 _igvn.register_new_node_with_optimizer(phi2);
2331 }
2332 // Register Phis with loop/block info
2333 set_ctrl(phi1, phi->in(0));
2334 set_ctrl(phi2, phi->in(0));
2335 // Make a new Cmp
2336 Node *cmp = sample_cmp->clone();
2337 cmp->set_req( 1, phi1 );
2338 cmp->set_req( 2, phi2 );
2339 _igvn.register_new_node_with_optimizer(cmp);
2340 set_ctrl(cmp, phi->in(0));
2341
2342 assert( cmp->is_Cmp(), "" );
2343 return (CmpNode*)cmp;
2344 }
2345
2346 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2347 IdealLoopTree* loop, IdealLoopTree* outer_loop,
2348 Node_List*& split_if_set, Node_List*& split_bool_set,
2349 Node_List*& split_cex_set, Node_List& worklist,
2350 uint new_counter, CloneLoopMode mode) {
2351 Node* nnn = old_new[old->_idx];
2352 // Copy uses to a worklist, so I can munge the def-use info
2353 // with impunity.
2354 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2355 worklist.push(old->fast_out(j));
2356
2357 while( worklist.size() ) {
2358 Node *use = worklist.pop();
2359 if (!has_node(use)) continue; // Ignore dead nodes
2360 if (use->in(0) == C->top()) continue;
2361 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2362 // Check for data-use outside of loop - at least one of OLD or USE
2363 // must not be a CFG node.
2364 #ifdef ASSERT
2365 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2366 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2367 assert(mode != IgnoreStripMined, "incorrect cloning mode");
2368 assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2369 }
2370 #endif
2371 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2372
2373 // If the Data use is an IF, that means we have an IF outside the
2374 // loop that is switching on a condition that is set inside the
2375 // loop. Happens if people set a loop-exit flag; then test the flag
2376 // in the loop to break the loop, then test is again outside the
2377 // loop to determine which way the loop exited.
2378 //
2379 // For several uses we need to make sure that there is no phi between,
2380 // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2381 // to avoid such a phi in between.
2382 // For example, it is unexpected that there is a Phi between an
2383 // AllocateArray node and its ValidLengthTest input that could cause
2384 // split if to break.
2385 assert(!use->is_OpaqueTemplateAssertionPredicate(),
2386 "should not clone a Template Assertion Predicate which should be removed once it's useless");
2387 if (use->is_If() || use->is_CMove() || use->is_OpaqueNotNull() || use->is_OpaqueInitializedAssertionPredicate() ||
2388 (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2389 // Since this code is highly unlikely, we lazily build the worklist
2390 // of such Nodes to go split.
2391 if (!split_if_set) {
2392 split_if_set = new Node_List();
2393 }
2394 split_if_set->push(use);
2395 }
2396 if (use->is_Bool()) {
2397 if (!split_bool_set) {
2398 split_bool_set = new Node_List();
2399 }
2400 split_bool_set->push(use);
2401 }
2402 if (use->Opcode() == Op_CreateEx) {
2403 if (!split_cex_set) {
2404 split_cex_set = new Node_List();
2405 }
2406 split_cex_set->push(use);
2407 }
2408
2409
2410 // Get "block" use is in
2411 uint idx = 0;
2412 while( use->in(idx) != old ) idx++;
2413 Node *prev = use->is_CFG() ? use : get_ctrl(use);
2414 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2415 Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2416 ? prev->in(2)
2417 : idom(prev);
2418 if( use->is_Phi() ) // Phi use is in prior block
2419 cfg = prev->in(idx); // NOT in block of Phi itself
2420 if (cfg->is_top()) { // Use is dead?
2421 _igvn.replace_input_of(use, idx, C->top());
2422 continue;
2423 }
2424
2425 // If use is referenced through control edge... (idx == 0)
2426 if (mode == IgnoreStripMined && idx == 0) {
2427 LoopNode *head = loop->_head->as_Loop();
2428 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2429 // That node is outside the inner loop, leave it outside the
2430 // outer loop as well to not confuse verification code.
2431 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2432 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2433 continue;
2434 }
2435 }
2436
2437 while(!outer_loop->is_member(get_loop(cfg))) {
2438 prev = cfg;
2439 cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2440 }
2441 // If the use occurs after merging several exits from the loop, then
2442 // old value must have dominated all those exits. Since the same old
2443 // value was used on all those exits we did not need a Phi at this
2444 // merge point. NOW we do need a Phi here. Each loop exit value
2445 // is now merged with the peeled body exit; each exit gets its own
2446 // private Phi and those Phis need to be merged here.
2447 Node *phi;
2448 if( prev->is_Region() ) {
2449 if( idx == 0 ) { // Updating control edge?
2450 phi = prev; // Just use existing control
2451 } else { // Else need a new Phi
2452 phi = PhiNode::make( prev, old );
2453 // Now recursively fix up the new uses of old!
2454 for( uint i = 1; i < prev->req(); i++ ) {
2455 worklist.push(phi); // Onto worklist once for each 'old' input
2456 }
2457 }
2458 } else {
2459 // Get new RegionNode merging old and new loop exits
2460 prev = old_new[prev->_idx];
2461 assert( prev, "just made this in step 7" );
2462 if( idx == 0) { // Updating control edge?
2463 phi = prev; // Just use existing control
2464 } else { // Else need a new Phi
2465 // Make a new Phi merging data values properly
2466 phi = PhiNode::make( prev, old );
2467 phi->set_req( 1, nnn );
2468 }
2469 }
2470 // If inserting a new Phi, check for prior hits
2471 if( idx != 0 ) {
2472 Node *hit = _igvn.hash_find_insert(phi);
2473 if( hit == nullptr ) {
2474 _igvn.register_new_node_with_optimizer(phi); // Register new phi
2475 } else { // or
2476 // Remove the new phi from the graph and use the hit
2477 _igvn.remove_dead_node(phi);
2478 phi = hit; // Use existing phi
2479 }
2480 set_ctrl(phi, prev);
2481 }
2482 // Make 'use' use the Phi instead of the old loop body exit value
2483 assert(use->in(idx) == old, "old is still input of use");
2484 // We notify all uses of old, including use, and the indirect uses,
2485 // that may now be optimized because we have replaced old with phi.
2486 _igvn.add_users_to_worklist(old);
2487 if (idx == 0 &&
2488 use->depends_only_on_test()) {
2489 Node* pinned_clone = use->pin_array_access_node();
2490 if (pinned_clone != nullptr) {
2491 // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path
2492 // into the region is left, an array load could become dependent on a condition that's not a range check for
2493 // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
2494 // floating above its range check.
2495 pinned_clone->set_req(0, phi);
2496 register_new_node_with_ctrl_of(pinned_clone, use);
2497 _igvn.replace_node(use, pinned_clone);
2498 continue;
2499 }
2500 }
2501 _igvn.replace_input_of(use, idx, phi);
2502 if( use->_idx >= new_counter ) { // If updating new phis
2503 // Not needed for correctness, but prevents a weak assert
2504 // in AddPNode from tripping (when we end up with different
2505 // base & derived Phis that will become the same after
2506 // IGVN does CSE).
2507 Node *hit = _igvn.hash_find_insert(use);
2508 if( hit ) // Go ahead and re-hash for hits.
2509 _igvn.replace_node( use, hit );
2510 }
2511 }
2512 }
2513 }
2514
2515 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2516 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2517 bool check_old_new) {
2518 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2519 Node* u = n->fast_out(j);
2520 assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2521 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2522 Node* c = phase->get_ctrl(u);
2523 IdealLoopTree* u_loop = phase->get_loop(c);
2524 assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2525 if (!loop->is_member(u_loop)) {
2526 if (outer_loop->is_member(u_loop)) {
2527 wq.push(u);
2528 } else {
2529 // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2530 // the outer loop too
2531 Node* u_c = u->in(0);
2532 if (u_c != nullptr) {
2533 IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2534 if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2535 wq.push(u);
2536 }
2537 }
2538 }
2539 }
2540 }
2541 }
2542 }
2543
2544 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2545 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2546 Node_List& extra_data_nodes) {
2547 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2548 CountedLoopNode* cl = head->as_CountedLoop();
2549 Node* l = cl->outer_loop();
2550 Node* tail = cl->outer_loop_tail();
2551 IfNode* le = cl->outer_loop_end();
2552 Node* sfpt = cl->outer_safepoint();
2553 CountedLoopEndNode* cle = cl->loopexit();
2554 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2555 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2556 Node* cle_out = cle->proj_out(false);
2557
2558 Node* new_sfpt = nullptr;
2559 Node* new_cle_out = cle_out->clone();
2560 old_new.map(cle_out->_idx, new_cle_out);
2561 if (mode == CloneIncludesStripMined) {
2562 // clone outer loop body
2563 Node* new_l = l->clone();
2564 Node* new_tail = tail->clone();
2565 IfNode* new_le = le->clone()->as_If();
2566 new_sfpt = sfpt->clone();
2567
2568 set_loop(new_l, outer_loop->_parent);
2569 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2570 set_loop(new_cle_out, outer_loop->_parent);
2571 set_idom(new_cle_out, new_cle, dd);
2572 set_loop(new_sfpt, outer_loop->_parent);
2573 set_idom(new_sfpt, new_cle_out, dd);
2574 set_loop(new_le, outer_loop->_parent);
2575 set_idom(new_le, new_sfpt, dd);
2576 set_loop(new_tail, outer_loop->_parent);
2577 set_idom(new_tail, new_le, dd);
2578 set_idom(new_cl, new_l, dd);
2579
2580 old_new.map(l->_idx, new_l);
2581 old_new.map(tail->_idx, new_tail);
2582 old_new.map(le->_idx, new_le);
2583 old_new.map(sfpt->_idx, new_sfpt);
2584
2585 new_l->set_req(LoopNode::LoopBackControl, new_tail);
2586 new_l->set_req(0, new_l);
2587 new_tail->set_req(0, new_le);
2588 new_le->set_req(0, new_sfpt);
2589 new_sfpt->set_req(0, new_cle_out);
2590 new_cle_out->set_req(0, new_cle);
2591 new_cl->set_req(LoopNode::EntryControl, new_l);
2592
2593 _igvn.register_new_node_with_optimizer(new_l);
2594 _igvn.register_new_node_with_optimizer(new_tail);
2595 _igvn.register_new_node_with_optimizer(new_le);
2596 } else {
2597 Node *newhead = old_new[loop->_head->_idx];
2598 newhead->as_Loop()->clear_strip_mined();
2599 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2600 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2601 }
2602 // Look at data node that were assigned a control in the outer
2603 // loop: they are kept in the outer loop by the safepoint so start
2604 // from the safepoint node's inputs.
2605 IdealLoopTree* outer_loop = get_loop(l);
2606 Node_Stack stack(2);
2607 stack.push(sfpt, 1);
2608 uint new_counter = C->unique();
2609 while (stack.size() > 0) {
2610 Node* n = stack.node();
2611 uint i = stack.index();
2612 while (i < n->req() &&
2613 (n->in(i) == nullptr ||
2614 !has_ctrl(n->in(i)) ||
2615 get_loop(get_ctrl(n->in(i))) != outer_loop ||
2616 (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2617 i++;
2618 }
2619 if (i < n->req()) {
2620 stack.set_index(i+1);
2621 stack.push(n->in(i), 0);
2622 } else {
2623 assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2624 Node* m = n == sfpt ? new_sfpt : n->clone();
2625 if (m != nullptr) {
2626 for (uint i = 0; i < n->req(); i++) {
2627 if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2628 m->set_req(i, old_new[m->in(i)->_idx]);
2629 }
2630 }
2631 } else {
2632 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2633 }
2634 if (n != sfpt) {
2635 extra_data_nodes.push(n);
2636 _igvn.register_new_node_with_optimizer(m);
2637 assert(get_ctrl(n) == cle_out, "what other control?");
2638 set_ctrl(m, new_cle_out);
2639 old_new.map(n->_idx, m);
2640 }
2641 stack.pop();
2642 }
2643 }
2644 if (mode == CloneIncludesStripMined) {
2645 _igvn.register_new_node_with_optimizer(new_sfpt);
2646 _igvn.register_new_node_with_optimizer(new_cle_out);
2647 }
2648 // Some other transformation may have pessimistically assigned some
2649 // data nodes to the outer loop. Set their control so they are out
2650 // of the outer loop.
2651 ResourceMark rm;
2652 Unique_Node_List wq;
2653 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2654 Node* old = extra_data_nodes.at(i);
2655 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2656 }
2657
2658 for (uint i = 0; i < loop->_body.size(); i++) {
2659 Node* old = loop->_body.at(i);
2660 collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2661 }
2662
2663 Node* inner_out = sfpt->in(0);
2664 if (inner_out->outcnt() > 1) {
2665 collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2666 }
2667
2668 Node* new_ctrl = cl->outer_loop_exit();
2669 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2670 for (uint i = 0; i < wq.size(); i++) {
2671 Node* n = wq.at(i);
2672 set_ctrl(n, new_ctrl);
2673 if (n->in(0) != nullptr) {
2674 _igvn.replace_input_of(n, 0, new_ctrl);
2675 }
2676 collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2677 }
2678 } else {
2679 Node *newhead = old_new[loop->_head->_idx];
2680 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2681 }
2682 }
2683
2684 //------------------------------clone_loop-------------------------------------
2685 //
2686 // C L O N E A L O O P B O D Y
2687 //
2688 // This is the basic building block of the loop optimizations. It clones an
2689 // entire loop body. It makes an old_new loop body mapping; with this mapping
2690 // you can find the new-loop equivalent to an old-loop node. All new-loop
2691 // nodes are exactly equal to their old-loop counterparts, all edges are the
2692 // same. All exits from the old-loop now have a RegionNode that merges the
2693 // equivalent new-loop path. This is true even for the normal "loop-exit"
2694 // condition. All uses of loop-invariant old-loop values now come from (one
2695 // or more) Phis that merge their new-loop equivalents.
2696 //
2697 // This operation leaves the graph in an illegal state: there are two valid
2698 // control edges coming from the loop pre-header to both loop bodies. I'll
2699 // definitely have to hack the graph after running this transform.
2700 //
2701 // From this building block I will further edit edges to perform loop peeling
2702 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2703 //
2704 // Parameter side_by_size_idom:
2705 // When side_by_size_idom is null, the dominator tree is constructed for
2706 // the clone loop to dominate the original. Used in construction of
2707 // pre-main-post loop sequence.
2708 // When nonnull, the clone and original are side-by-side, both are
2709 // dominated by the side_by_side_idom node. Used in construction of
2710 // unswitched loops.
2711 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2712 CloneLoopMode mode, Node* side_by_side_idom) {
2713
2714 LoopNode* head = loop->_head->as_Loop();
2715 head->verify_strip_mined(1);
2716
2717 if (C->do_vector_loop() && PrintOpto) {
2718 const char* mname = C->method()->name()->as_quoted_ascii();
2719 if (mname != nullptr) {
2720 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2721 }
2722 }
2723
2724 CloneMap& cm = C->clone_map();
2725 if (C->do_vector_loop()) {
2726 cm.set_clone_idx(cm.max_gen()+1);
2727 #ifndef PRODUCT
2728 if (PrintOpto) {
2729 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2730 loop->dump_head();
2731 }
2732 #endif
2733 }
2734
2735 // Step 1: Clone the loop body. Make the old->new mapping.
2736 clone_loop_body(loop->_body, old_new, &cm);
2737
2738 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2739
2740 // Step 2: Fix the edges in the new body. If the old input is outside the
2741 // loop use it. If the old input is INside the loop, use the corresponding
2742 // new node instead.
2743 fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2744
2745 Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2746 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2747
2748 // Step 3: Now fix control uses. Loop varying control uses have already
2749 // been fixed up (as part of all input edges in Step 2). Loop invariant
2750 // control uses must be either an IfFalse or an IfTrue. Make a merge
2751 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2752 // refer to this.
2753 Node_List worklist;
2754 uint new_counter = C->unique();
2755 fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2756
2757 // Step 4: If loop-invariant use is not control, it must be dominated by a
2758 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2759 // there if needed. Make a Phi there merging old and new used values.
2760 Node_List *split_if_set = nullptr;
2761 Node_List *split_bool_set = nullptr;
2762 Node_List *split_cex_set = nullptr;
2763 fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2764
2765 for (uint i = 0; i < extra_data_nodes.size(); i++) {
2766 Node* old = extra_data_nodes.at(i);
2767 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2768 split_bool_set, split_cex_set, worklist, new_counter,
2769 mode);
2770 }
2771
2772 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2773 // the loop uses a condition set in the loop. The original IF probably
2774 // takes control from one or more OLD Regions (which in turn get from NEW
2775 // Regions). In any case, there will be a set of Phis for each merge point
2776 // from the IF up to where the original BOOL def exists the loop.
2777 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2778
2779 }
2780
2781 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2782 if (split_if_set) {
2783 while (split_if_set->size()) {
2784 Node *iff = split_if_set->pop();
2785 uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2786 if (iff->in(input)->is_Phi()) {
2787 Node *b = clone_iff(iff->in(input)->as_Phi());
2788 _igvn.replace_input_of(iff, input, b);
2789 }
2790 }
2791 }
2792 if (split_bool_set) {
2793 while (split_bool_set->size()) {
2794 Node *b = split_bool_set->pop();
2795 Node *phi = b->in(1);
2796 assert(phi->is_Phi(), "");
2797 CmpNode *cmp = clone_bool((PhiNode*) phi);
2798 _igvn.replace_input_of(b, 1, cmp);
2799 }
2800 }
2801 if (split_cex_set) {
2802 while (split_cex_set->size()) {
2803 Node *b = split_cex_set->pop();
2804 assert(b->in(0)->is_Region(), "");
2805 assert(b->in(1)->is_Phi(), "");
2806 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2807 split_up(b, b->in(0), nullptr);
2808 }
2809 }
2810 }
2811
2812 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2813 uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2814 Node_List*& split_bool_set, Node_List*& split_cex_set) {
2815 for(uint i = 0; i < body.size(); i++ ) {
2816 Node* old = body.at(i);
2817 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2818 split_bool_set, split_cex_set, worklist, new_counter,
2819 mode);
2820 }
2821 }
2822
2823 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2824 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2825 LoopNode* head = loop->_head->as_Loop();
2826 for(uint i = 0; i < body.size(); i++ ) {
2827 Node* old = body.at(i);
2828 if( !old->is_CFG() ) continue;
2829
2830 // Copy uses to a worklist, so I can munge the def-use info
2831 // with impunity.
2832 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2833 worklist.push(old->fast_out(j));
2834 }
2835
2836 while (worklist.size()) { // Visit all uses
2837 Node *use = worklist.pop();
2838 if (!has_node(use)) continue; // Ignore dead nodes
2839 IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2840 if (!loop->is_member(use_loop) && use->is_CFG()) {
2841 // Both OLD and USE are CFG nodes here.
2842 assert(use->is_Proj(), "" );
2843 Node* nnn = old_new[old->_idx];
2844
2845 Node* newuse = nullptr;
2846 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2847 CountedLoopNode* cl = head->as_CountedLoop();
2848 CountedLoopEndNode* cle = cl->loopexit();
2849 Node* cle_out = cle->proj_out_or_null(false);
2850 if (use == cle_out) {
2851 IfNode* le = cl->outer_loop_end();
2852 use = le->proj_out(false);
2853 use_loop = get_loop(use);
2854 if (mode == CloneIncludesStripMined) {
2855 nnn = old_new[le->_idx];
2856 } else {
2857 newuse = old_new[cle_out->_idx];
2858 }
2859 }
2860 }
2861 if (newuse == nullptr) {
2862 newuse = use->clone();
2863 }
2864
2865 // Clone the loop exit control projection
2866 if (C->do_vector_loop() && cm != nullptr) {
2867 cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2868 }
2869 newuse->set_req(0,nnn);
2870 _igvn.register_new_node_with_optimizer(newuse);
2871 set_loop(newuse, use_loop);
2872 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2873
2874 // We need a Region to merge the exit from the peeled body and the
2875 // exit from the old loop body.
2876 RegionNode *r = new RegionNode(3);
2877 uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2878 assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2879
2880 // The original user of 'use' uses 'r' instead.
2881 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2882 Node* useuse = use->last_out(l);
2883 _igvn.rehash_node_delayed(useuse);
2884 uint uses_found = 0;
2885 if (useuse->in(0) == use) {
2886 useuse->set_req(0, r);
2887 uses_found++;
2888 if (useuse->is_CFG()) {
2889 // This is not a dom_depth > dd_r because when new
2890 // control flow is constructed by a loop opt, a node and
2891 // its dominator can end up at the same dom_depth
2892 assert(dom_depth(useuse) >= dd_r, "");
2893 set_idom(useuse, r, dom_depth(useuse));
2894 }
2895 }
2896 for (uint k = 1; k < useuse->req(); k++) {
2897 if( useuse->in(k) == use ) {
2898 useuse->set_req(k, r);
2899 uses_found++;
2900 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2901 // This is not a dom_depth > dd_r because when new
2902 // control flow is constructed by a loop opt, a node
2903 // and its dominator can end up at the same dom_depth
2904 assert(dom_depth(useuse) >= dd_r , "");
2905 set_idom(useuse, r, dom_depth(useuse));
2906 }
2907 }
2908 }
2909 l -= uses_found; // we deleted 1 or more copies of this edge
2910 }
2911
2912 assert(use->is_Proj(), "loop exit should be projection");
2913 // lazy_replace() below moves all nodes that are:
2914 // - control dependent on the loop exit or
2915 // - have control set to the loop exit
2916 // below the post-loop merge point. lazy_replace() takes a dead control as first input. To make it
2917 // possible to use it, the loop exit projection is cloned and becomes the new exit projection. The initial one
2918 // becomes dead and is "replaced" by the region.
2919 Node* use_clone = use->clone();
2920 register_control(use_clone, use_loop, idom(use), dom_depth(use));
2921 // Now finish up 'r'
2922 r->set_req(1, newuse);
2923 r->set_req(2, use_clone);
2924 _igvn.register_new_node_with_optimizer(r);
2925 set_loop(r, use_loop);
2926 set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2927 lazy_replace(use, r);
2928 // Map the (cloned) old use to the new merge point
2929 old_new.map(use_clone->_idx, r);
2930 } // End of if a loop-exit test
2931 }
2932 }
2933 }
2934
2935 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2936 IdealLoopTree* parent, bool partial) {
2937 for(uint i = 0; i < body.size(); i++ ) {
2938 Node *old = body.at(i);
2939 Node *nnn = old_new[old->_idx];
2940 // Fix CFG/Loop controlling the new node
2941 if (has_ctrl(old)) {
2942 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2943 } else {
2944 set_loop(nnn, parent);
2945 if (old->outcnt() > 0) {
2946 Node* dom = idom(old);
2947 if (old_new[dom->_idx] != nullptr) {
2948 dom = old_new[dom->_idx];
2949 set_idom(nnn, dom, dd );
2950 }
2951 }
2952 }
2953 // Correct edges to the new node
2954 for (uint j = 0; j < nnn->req(); j++) {
2955 Node *n = nnn->in(j);
2956 if (n != nullptr) {
2957 IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2958 if (loop->is_member(old_in_loop)) {
2959 if (old_new[n->_idx] != nullptr) {
2960 nnn->set_req(j, old_new[n->_idx]);
2961 } else {
2962 assert(!body.contains(n), "");
2963 assert(partial, "node not cloned");
2964 }
2965 }
2966 }
2967 }
2968 _igvn.hash_find_insert(nnn);
2969 }
2970 }
2971
2972 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2973 for (uint i = 0; i < body.size(); i++) {
2974 Node* old = body.at(i);
2975 Node* nnn = old->clone();
2976 old_new.map(old->_idx, nnn);
2977 if (C->do_vector_loop() && cm != nullptr) {
2978 cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2979 }
2980 _igvn.register_new_node_with_optimizer(nnn);
2981 }
2982 }
2983
2984
2985 //---------------------- stride_of_possible_iv -------------------------------------
2986 // Looks for an iff/bool/comp with one operand of the compare
2987 // being a cycle involving an add and a phi,
2988 // with an optional truncation (left-shift followed by a right-shift)
2989 // of the add. Returns zero if not an iv.
2990 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2991 Node* trunc1 = nullptr;
2992 Node* trunc2 = nullptr;
2993 const TypeInteger* ttype = nullptr;
2994 if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
2995 return 0;
2996 }
2997 BoolNode* bl = iff->in(1)->as_Bool();
2998 Node* cmp = bl->in(1);
2999 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
3000 return 0;
3001 }
3002 // Must have an invariant operand
3003 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
3004 return 0;
3005 }
3006 Node* add2 = nullptr;
3007 Node* cmp1 = cmp->in(1);
3008 if (cmp1->is_Phi()) {
3009 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
3010 Node* phi = cmp1;
3011 for (uint i = 1; i < phi->req(); i++) {
3012 Node* in = phi->in(i);
3013 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
3014 &trunc1, &trunc2, &ttype, T_INT);
3015 if (add && add->in(1) == phi) {
3016 add2 = add->in(2);
3017 break;
3018 }
3019 }
3020 } else {
3021 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
3022 Node* addtrunc = cmp1;
3023 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
3024 &trunc1, &trunc2, &ttype, T_INT);
3025 if (add && add->in(1)->is_Phi()) {
3026 Node* phi = add->in(1);
3027 for (uint i = 1; i < phi->req(); i++) {
3028 if (phi->in(i) == addtrunc) {
3029 add2 = add->in(2);
3030 break;
3031 }
3032 }
3033 }
3034 }
3035 if (add2 != nullptr) {
3036 const TypeInt* add2t = _igvn.type(add2)->is_int();
3037 if (add2t->is_con()) {
3038 return add2t->get_con();
3039 }
3040 }
3041 return 0;
3042 }
3043
3044
3045 //---------------------- stay_in_loop -------------------------------------
3046 // Return the (unique) control output node that's in the loop (if it exists.)
3047 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
3048 Node* unique = nullptr;
3049 if (!n) return nullptr;
3050 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3051 Node* use = n->fast_out(i);
3052 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
3053 if (unique != nullptr) {
3054 return nullptr;
3055 }
3056 unique = use;
3057 }
3058 }
3059 return unique;
3060 }
3061
3062 //------------------------------ register_node -------------------------------------
3063 // Utility to register node "n" with PhaseIdealLoop
3064 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
3065 _igvn.register_new_node_with_optimizer(n);
3066 loop->_body.push(n);
3067 if (n->is_CFG()) {
3068 set_loop(n, loop);
3069 set_idom(n, pred, ddepth);
3070 } else {
3071 set_ctrl(n, pred);
3072 }
3073 }
3074
3075 //------------------------------ proj_clone -------------------------------------
3076 // Utility to create an if-projection
3077 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
3078 ProjNode* c = p->clone()->as_Proj();
3079 c->set_req(0, iff);
3080 return c;
3081 }
3082
3083 //------------------------------ short_circuit_if -------------------------------------
3084 // Force the iff control output to be the live_proj
3085 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
3086 guarantee(live_proj != nullptr, "null projection");
3087 int proj_con = live_proj->_con;
3088 assert(proj_con == 0 || proj_con == 1, "false or true projection");
3089 Node *con = _igvn.intcon(proj_con);
3090 set_ctrl(con, C->root());
3091 if (iff) {
3092 iff->set_req(1, con);
3093 }
3094 return con;
3095 }
3096
3097 //------------------------------ insert_if_before_proj -------------------------------------
3098 // Insert a new if before an if projection (* - new node)
3099 //
3100 // before
3101 // if(test)
3102 // / \
3103 // v v
3104 // other-proj proj (arg)
3105 //
3106 // after
3107 // if(test)
3108 // / \
3109 // / v
3110 // | * proj-clone
3111 // v |
3112 // other-proj v
3113 // * new_if(relop(cmp[IU](left,right)))
3114 // / \
3115 // v v
3116 // * new-proj proj
3117 // (returned)
3118 //
3119 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
3120 IfNode* iff = proj->in(0)->as_If();
3121 IdealLoopTree *loop = get_loop(proj);
3122 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3123 uint ddepth = dom_depth(proj);
3124
3125 _igvn.rehash_node_delayed(iff);
3126 _igvn.rehash_node_delayed(proj);
3127
3128 proj->set_req(0, nullptr); // temporary disconnect
3129 ProjNode* proj2 = proj_clone(proj, iff);
3130 register_node(proj2, loop, iff, ddepth);
3131
3132 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
3133 register_node(cmp, loop, proj2, ddepth);
3134
3135 BoolNode* bol = new BoolNode(cmp, relop);
3136 register_node(bol, loop, proj2, ddepth);
3137
3138 int opcode = iff->Opcode();
3139 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
3140 IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
3141 register_node(new_if, loop, proj2, ddepth);
3142
3143 proj->set_req(0, new_if); // reattach
3144 set_idom(proj, new_if, ddepth);
3145
3146 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
3147 guarantee(new_exit != nullptr, "null exit node");
3148 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
3149
3150 return new_exit;
3151 }
3152
3153 //------------------------------ insert_region_before_proj -------------------------------------
3154 // Insert a region before an if projection (* - new node)
3155 //
3156 // before
3157 // if(test)
3158 // / |
3159 // v |
3160 // proj v
3161 // other-proj
3162 //
3163 // after
3164 // if(test)
3165 // / |
3166 // v |
3167 // * proj-clone v
3168 // | other-proj
3169 // v
3170 // * new-region
3171 // |
3172 // v
3173 // * dum_if
3174 // / \
3175 // v \
3176 // * dum-proj v
3177 // proj
3178 //
3179 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3180 IfNode* iff = proj->in(0)->as_If();
3181 IdealLoopTree *loop = get_loop(proj);
3182 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3183 uint ddepth = dom_depth(proj);
3184
3185 _igvn.rehash_node_delayed(iff);
3186 _igvn.rehash_node_delayed(proj);
3187
3188 proj->set_req(0, nullptr); // temporary disconnect
3189 ProjNode* proj2 = proj_clone(proj, iff);
3190 register_node(proj2, loop, iff, ddepth);
3191
3192 RegionNode* reg = new RegionNode(2);
3193 reg->set_req(1, proj2);
3194 register_node(reg, loop, iff, ddepth);
3195
3196 IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3197 register_node(dum_if, loop, reg, ddepth);
3198
3199 proj->set_req(0, dum_if); // reattach
3200 set_idom(proj, dum_if, ddepth);
3201
3202 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3203 register_node(dum_proj, loop, dum_if, ddepth);
3204
3205 return reg;
3206 }
3207
3208 // Idea
3209 // ----
3210 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3211 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3212 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3213 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3214 // test alone instead:
3215 //
3216 // Before Partial Peeling:
3217 // Loop:
3218 // <peeled section>
3219 // Split off signed loop exit test
3220 // <-- CUT HERE -->
3221 // Unchanged unsigned loop exit test
3222 // <rest of unpeeled section>
3223 // goto Loop
3224 //
3225 // After Partial Peeling:
3226 // <cloned peeled section>
3227 // Cloned split off signed loop exit test
3228 // Loop:
3229 // Unchanged unsigned loop exit test
3230 // <rest of unpeeled section>
3231 // <peeled section>
3232 // Split off signed loop exit test
3233 // goto Loop
3234 //
3235 // Details
3236 // -------
3237 // Before:
3238 // if (i <u limit) Unsigned loop exit condition
3239 // / |
3240 // v v
3241 // exit-proj stay-in-loop-proj
3242 //
3243 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3244 // before the CmpU on the stay-in-loop path and keep both tests:
3245 //
3246 // if (i <u limit) Signed loop exit test
3247 // / |
3248 // / if (i <u limit) Unsigned loop exit test
3249 // / / |
3250 // v v v
3251 // exit-region stay-in-loop-proj
3252 //
3253 // Implementation
3254 // --------------
3255 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3256 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3257 // exit tests is preserved, and their loop nesting is correct.
3258 //
3259 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3260 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3261 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3262 //
3263 // if (stay-in-loop-const) Killed original unsigned loop exit test
3264 // / |
3265 // / v
3266 // / if (i < limit) Split off signed loop exit test
3267 // / / |
3268 // / / v
3269 // / / if (i <u limit) Cloned unsigned loop exit test
3270 // / / / |
3271 // v v v |
3272 // exit-region |
3273 // | |
3274 // dummy-if |
3275 // / | |
3276 // dead | |
3277 // v v
3278 // exit-proj stay-in-loop-proj
3279 //
3280 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3281 // loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3282 //
3283 // Requirements
3284 // ------------
3285 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3286 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3287 // Otherwise, we need to bail out (see comments in the code below).
3288 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3289 const bool Signed = true;
3290 const bool Unsigned = false;
3291
3292 BoolNode* bol = if_cmpu->in(1)->as_Bool();
3293 if (bol->_test._test != BoolTest::lt) {
3294 return nullptr;
3295 }
3296 CmpNode* cmpu = bol->in(1)->as_Cmp();
3297 assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3298
3299 int stride = stride_of_possible_iv(if_cmpu);
3300 if (stride == 0) {
3301 return nullptr;
3302 }
3303
3304 Node* lp_proj = stay_in_loop(if_cmpu, loop);
3305 guarantee(lp_proj != nullptr, "null loop node");
3306
3307 ProjNode* lp_continue = lp_proj->as_Proj();
3308 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3309 if (!lp_exit->is_IfFalse()) {
3310 // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3311 // We therefore can't add a single exit condition.
3312 return nullptr;
3313 }
3314 // The unsigned loop exit condition is
3315 // !(i <u limit)
3316 // = i >=u limit
3317 //
3318 // First, we note that for any x for which
3319 // 0 <= x <= INT_MAX
3320 // we can convert x to an unsigned int and still get the same guarantee:
3321 // 0 <= (uint) x <= INT_MAX = (uint) INT_MAX
3322 // 0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX (LEMMA)
3323 //
3324 // With that in mind, if
3325 // limit >= 0 (COND)
3326 // then the unsigned loop exit condition
3327 // i >=u limit (ULE)
3328 // is equivalent to
3329 // i < 0 || i >= limit (SLE-full)
3330 // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3331 // (uint) i >=u MAX_INT >= limit >= 0
3332 // or otherwise
3333 // i >= limit >= 0
3334 // holds due to (LEMMA).
3335 //
3336 // For completeness, a counterexample with limit < 0:
3337 // Assume i = -3 and limit = -2:
3338 // i < 0
3339 // -2 < 0
3340 // is true and thus also "i < 0 || i >= limit". But
3341 // i >=u limit
3342 // -3 >=u -2
3343 // is false.
3344 Node* limit = cmpu->in(2);
3345 const TypeInt* type_limit = _igvn.type(limit)->is_int();
3346 if (type_limit->_lo < 0) {
3347 return nullptr;
3348 }
3349
3350 // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3351 // stride < 0:
3352 // i < 0 (SLE = SLE-negative)
3353 // stride > 0:
3354 // i >= limit (SLE = SLE-positive)
3355 // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3356 //
3357 // Loop:
3358 // <peeled section>
3359 // i >= limit (SLE-positive)
3360 // <-- CUT HERE -->
3361 // i >=u limit (ULE)
3362 // <rest of unpeeled section>
3363 // goto Loop
3364 //
3365 // We exit the loop if:
3366 // (SLE) is true OR (ULE) is true
3367 // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3368 // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3369 // (SLE) IMPLIES (ULE)
3370 // This indeed holds when (COND) is given:
3371 // - stride > 0:
3372 // i >= limit // (SLE = SLE-positive)
3373 // i >= limit >= 0 // (COND)
3374 // i >=u limit >= 0 // (LEMMA)
3375 // which is the unsigned loop exit condition (ULE).
3376 // - stride < 0:
3377 // i < 0 // (SLE = SLE-negative)
3378 // (uint) i >u MAX_INT // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3379 // MAX_INT >= limit >= 0 // (COND)
3380 // MAX_INT >=u limit >= 0 // (LEMMA)
3381 // and thus from (NEG) and (LEMMA):
3382 // i >=u limit
3383 // which is the unsigned loop exit condition (ULE).
3384 //
3385 //
3386 // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3387 // <cloned peeled section>
3388 // i >= limit (SLE-positive)
3389 // Loop:
3390 // i >=u limit (ULE)
3391 // <rest of unpeeled section>
3392 // <peeled section>
3393 // i >= limit (SLE-positive)
3394 // goto Loop
3395 Node* rhs_cmpi;
3396 if (stride > 0) {
3397 rhs_cmpi = limit; // For i >= limit
3398 } else {
3399 rhs_cmpi = _igvn.makecon(TypeInt::ZERO); // For i < 0
3400 set_ctrl(rhs_cmpi, C->root());
3401 }
3402 // Create a new region on the exit path
3403 RegionNode* reg = insert_region_before_proj(lp_exit);
3404 guarantee(reg != nullptr, "null region node");
3405
3406 // Clone the if-cmpu-true-false using a signed compare
3407 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3408 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3409 reg->add_req(cmpi_exit);
3410
3411 // Clone the if-cmpu-true-false
3412 BoolTest::mask rel_u = bol->_test._test;
3413 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3414 reg->add_req(cmpu_exit);
3415
3416 // Force original if to stay in loop.
3417 short_circuit_if(if_cmpu, lp_continue);
3418
3419 return cmpi_exit->in(0)->as_If();
3420 }
3421
3422 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3423 // Remove a previously inserted signed compare loop exit.
3424 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3425 Node* lp_proj = stay_in_loop(if_cmp, loop);
3426 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3427 stay_in_loop(lp_proj, loop)->is_If() &&
3428 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3429 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3430 set_ctrl(con, C->root());
3431 if_cmp->set_req(1, con);
3432 }
3433
3434 //------------------------------ scheduled_nodelist -------------------------------------
3435 // Create a post order schedule of nodes that are in the
3436 // "member" set. The list is returned in "sched".
3437 // The first node in "sched" is the loop head, followed by
3438 // nodes which have no inputs in the "member" set, and then
3439 // followed by the nodes that have an immediate input dependence
3440 // on a node in "sched".
3441 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3442
3443 assert(member.test(loop->_head->_idx), "loop head must be in member set");
3444 VectorSet visited;
3445 Node_Stack nstack(loop->_body.size());
3446
3447 Node* n = loop->_head; // top of stack is cached in "n"
3448 uint idx = 0;
3449 visited.set(n->_idx);
3450
3451 // Initially push all with no inputs from within member set
3452 for(uint i = 0; i < loop->_body.size(); i++ ) {
3453 Node *elt = loop->_body.at(i);
3454 if (member.test(elt->_idx)) {
3455 bool found = false;
3456 for (uint j = 0; j < elt->req(); j++) {
3457 Node* def = elt->in(j);
3458 if (def && member.test(def->_idx) && def != elt) {
3459 found = true;
3460 break;
3461 }
3462 }
3463 if (!found && elt != loop->_head) {
3464 nstack.push(n, idx);
3465 n = elt;
3466 assert(!visited.test(n->_idx), "not seen yet");
3467 visited.set(n->_idx);
3468 }
3469 }
3470 }
3471
3472 // traverse out's that are in the member set
3473 while (true) {
3474 if (idx < n->outcnt()) {
3475 Node* use = n->raw_out(idx);
3476 idx++;
3477 if (!visited.test_set(use->_idx)) {
3478 if (member.test(use->_idx)) {
3479 nstack.push(n, idx);
3480 n = use;
3481 idx = 0;
3482 }
3483 }
3484 } else {
3485 // All outputs processed
3486 sched.push(n);
3487 if (nstack.is_empty()) break;
3488 n = nstack.node();
3489 idx = nstack.index();
3490 nstack.pop();
3491 }
3492 }
3493 }
3494
3495
3496 //------------------------------ has_use_in_set -------------------------------------
3497 // Has a use in the vector set
3498 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3499 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3500 Node* use = n->fast_out(j);
3501 if (vset.test(use->_idx)) {
3502 return true;
3503 }
3504 }
3505 return false;
3506 }
3507
3508
3509 //------------------------------ has_use_internal_to_set -------------------------------------
3510 // Has use internal to the vector set (ie. not in a phi at the loop head)
3511 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3512 Node* head = loop->_head;
3513 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3514 Node* use = n->fast_out(j);
3515 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3516 return true;
3517 }
3518 }
3519 return false;
3520 }
3521
3522
3523 //------------------------------ clone_for_use_outside_loop -------------------------------------
3524 // clone "n" for uses that are outside of loop
3525 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3526 int cloned = 0;
3527 assert(worklist.size() == 0, "should be empty");
3528 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3529 Node* use = n->fast_out(j);
3530 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3531 worklist.push(use);
3532 }
3533 }
3534
3535 if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3536 "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3537 return -1;
3538 }
3539
3540 while( worklist.size() ) {
3541 Node *use = worklist.pop();
3542 if (!has_node(use) || use->in(0) == C->top()) continue;
3543 uint j;
3544 for (j = 0; j < use->req(); j++) {
3545 if (use->in(j) == n) break;
3546 }
3547 assert(j < use->req(), "must be there");
3548
3549 // clone "n" and insert it between the inputs of "n" and the use outside the loop
3550 Node* n_clone = n->clone();
3551 _igvn.replace_input_of(use, j, n_clone);
3552 cloned++;
3553 Node* use_c;
3554 if (!use->is_Phi()) {
3555 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3556 } else {
3557 // Use in a phi is considered a use in the associated predecessor block
3558 use_c = use->in(0)->in(j);
3559 }
3560 set_ctrl(n_clone, use_c);
3561 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3562 get_loop(use_c)->_body.push(n_clone);
3563 _igvn.register_new_node_with_optimizer(n_clone);
3564 #ifndef PRODUCT
3565 if (TracePartialPeeling) {
3566 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3567 }
3568 #endif
3569 }
3570 return cloned;
3571 }
3572
3573
3574 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3575 // clone "n" for special uses that are in the not_peeled region.
3576 // If these def-uses occur in separate blocks, the code generator
3577 // marks the method as not compilable. For example, if a "BoolNode"
3578 // is in a different basic block than the "IfNode" that uses it, then
3579 // the compilation is aborted in the code generator.
3580 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3581 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3582 if (n->is_Phi() || n->is_Load()) {
3583 return;
3584 }
3585 assert(worklist.size() == 0, "should be empty");
3586 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3587 Node* use = n->fast_out(j);
3588 if ( not_peel.test(use->_idx) &&
3589 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
3590 use->in(1) == n) {
3591 worklist.push(use);
3592 }
3593 }
3594 if (worklist.size() > 0) {
3595 // clone "n" and insert it between inputs of "n" and the use
3596 Node* n_clone = n->clone();
3597 loop->_body.push(n_clone);
3598 _igvn.register_new_node_with_optimizer(n_clone);
3599 set_ctrl(n_clone, get_ctrl(n));
3600 sink_list.push(n_clone);
3601 not_peel.set(n_clone->_idx);
3602 #ifndef PRODUCT
3603 if (TracePartialPeeling) {
3604 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3605 }
3606 #endif
3607 while( worklist.size() ) {
3608 Node *use = worklist.pop();
3609 _igvn.rehash_node_delayed(use);
3610 for (uint j = 1; j < use->req(); j++) {
3611 if (use->in(j) == n) {
3612 use->set_req(j, n_clone);
3613 }
3614 }
3615 }
3616 }
3617 }
3618
3619
3620 //------------------------------ insert_phi_for_loop -------------------------------------
3621 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3622 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3623 Node *phi = PhiNode::make(lp, back_edge_val);
3624 phi->set_req(LoopNode::EntryControl, lp_entry_val);
3625 // Use existing phi if it already exists
3626 Node *hit = _igvn.hash_find_insert(phi);
3627 if( hit == nullptr ) {
3628 _igvn.register_new_node_with_optimizer(phi);
3629 set_ctrl(phi, lp);
3630 } else {
3631 // Remove the new phi from the graph and use the hit
3632 _igvn.remove_dead_node(phi);
3633 phi = hit;
3634 }
3635 _igvn.replace_input_of(use, idx, phi);
3636 }
3637
3638 #ifdef ASSERT
3639 //------------------------------ is_valid_loop_partition -------------------------------------
3640 // Validate the loop partition sets: peel and not_peel
3641 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3642 VectorSet& not_peel ) {
3643 uint i;
3644 // Check that peel_list entries are in the peel set
3645 for (i = 0; i < peel_list.size(); i++) {
3646 if (!peel.test(peel_list.at(i)->_idx)) {
3647 return false;
3648 }
3649 }
3650 // Check at loop members are in one of peel set or not_peel set
3651 for (i = 0; i < loop->_body.size(); i++ ) {
3652 Node *def = loop->_body.at(i);
3653 uint di = def->_idx;
3654 // Check that peel set elements are in peel_list
3655 if (peel.test(di)) {
3656 if (not_peel.test(di)) {
3657 return false;
3658 }
3659 // Must be in peel_list also
3660 bool found = false;
3661 for (uint j = 0; j < peel_list.size(); j++) {
3662 if (peel_list.at(j)->_idx == di) {
3663 found = true;
3664 break;
3665 }
3666 }
3667 if (!found) {
3668 return false;
3669 }
3670 } else if (not_peel.test(di)) {
3671 if (peel.test(di)) {
3672 return false;
3673 }
3674 } else {
3675 return false;
3676 }
3677 }
3678 return true;
3679 }
3680
3681 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3682 // Ensure a use outside of loop is of the right form
3683 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3684 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3685 return (use->is_Phi() &&
3686 use_c->is_Region() && use_c->req() == 3 &&
3687 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3688 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3689 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3690 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3691 }
3692
3693 //------------------------------ is_valid_clone_loop_form -------------------------------------
3694 // Ensure that all uses outside of loop are of the right form
3695 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3696 uint orig_exit_idx, uint clone_exit_idx) {
3697 uint len = peel_list.size();
3698 for (uint i = 0; i < len; i++) {
3699 Node *def = peel_list.at(i);
3700
3701 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3702 Node *use = def->fast_out(j);
3703 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3704 if (!loop->is_member(get_loop(use_c))) {
3705 // use is not in the loop, check for correct structure
3706 if (use->in(0) == def) {
3707 // Okay
3708 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3709 return false;
3710 }
3711 }
3712 }
3713 }
3714 return true;
3715 }
3716 #endif
3717
3718 //------------------------------ partial_peel -------------------------------------
3719 // Partially peel (aka loop rotation) the top portion of a loop (called
3720 // the peel section below) by cloning it and placing one copy just before
3721 // the new loop head and the other copy at the bottom of the new loop.
3722 //
3723 // before after where it came from
3724 //
3725 // stmt1 stmt1
3726 // loop: stmt2 clone
3727 // stmt2 if condA goto exitA clone
3728 // if condA goto exitA new_loop: new
3729 // stmt3 stmt3 clone
3730 // if !condB goto loop if condB goto exitB clone
3731 // exitB: stmt2 orig
3732 // stmt4 if !condA goto new_loop orig
3733 // exitA: goto exitA
3734 // exitB:
3735 // stmt4
3736 // exitA:
3737 //
3738 // Step 1: find the cut point: an exit test on probable
3739 // induction variable.
3740 // Step 2: schedule (with cloning) operations in the peel
3741 // section that can be executed after the cut into
3742 // the section that is not peeled. This may need
3743 // to clone operations into exit blocks. For
3744 // instance, a reference to A[i] in the not-peel
3745 // section and a reference to B[i] in an exit block
3746 // may cause a left-shift of i by 2 to be placed
3747 // in the peel block. This step will clone the left
3748 // shift into the exit block and sink the left shift
3749 // from the peel to the not-peel section.
3750 // Step 3: clone the loop, retarget the control, and insert
3751 // phis for values that are live across the new loop
3752 // head. This is very dependent on the graph structure
3753 // from clone_loop. It creates region nodes for
3754 // exit control and associated phi nodes for values
3755 // flow out of the loop through that exit. The region
3756 // node is dominated by the clone's control projection.
3757 // So the clone's peel section is placed before the
3758 // new loop head, and the clone's not-peel section is
3759 // forms the top part of the new loop. The original
3760 // peel section forms the tail of the new loop.
3761 // Step 4: update the dominator tree and recompute the
3762 // dominator depth.
3763 //
3764 // orig
3765 //
3766 // stmt1
3767 // |
3768 // v
3769 // predicates
3770 // |
3771 // v
3772 // loop<----+
3773 // | |
3774 // stmt2 |
3775 // | |
3776 // v |
3777 // ifA |
3778 // / | |
3779 // v v |
3780 // false true ^ <-- last_peel
3781 // / | |
3782 // / ===|==cut |
3783 // / stmt3 | <-- first_not_peel
3784 // / | |
3785 // | v |
3786 // v ifB |
3787 // exitA: / \ |
3788 // / \ |
3789 // v v |
3790 // false true |
3791 // / \ |
3792 // / ----+
3793 // |
3794 // v
3795 // exitB:
3796 // stmt4
3797 //
3798 //
3799 // after clone loop
3800 //
3801 // stmt1
3802 // |
3803 // v
3804 // predicates
3805 // / \
3806 // clone / \ orig
3807 // / \
3808 // / \
3809 // v v
3810 // +---->loop loop<----+
3811 // | | | |
3812 // | stmt2 stmt2 |
3813 // | | | |
3814 // | v v |
3815 // | ifA ifA |
3816 // | | \ / | |
3817 // | v v v v |
3818 // ^ true false false true ^ <-- last_peel
3819 // | | ^ \ / | |
3820 // | cut==|== \ \ / ===|==cut |
3821 // | stmt3 \ \ / stmt3 | <-- first_not_peel
3822 // | | dom | | | |
3823 // | v \ 1v v2 v |
3824 // | ifB regionA ifB |
3825 // | / \ | / \ |
3826 // | / \ v / \ |
3827 // | v v exitA: v v |
3828 // | true false false true |
3829 // | / ^ \ / \ |
3830 // +---- \ \ / ----+
3831 // dom \ /
3832 // \ 1v v2
3833 // regionB
3834 // |
3835 // v
3836 // exitB:
3837 // stmt4
3838 //
3839 //
3840 // after partial peel
3841 //
3842 // stmt1
3843 // |
3844 // v
3845 // predicates
3846 // /
3847 // clone / orig
3848 // / TOP
3849 // / \
3850 // v v
3851 // TOP->loop loop----+
3852 // | | |
3853 // stmt2 stmt2 |
3854 // | | |
3855 // v v |
3856 // ifA ifA |
3857 // | \ / | |
3858 // v v v v |
3859 // true false false true | <-- last_peel
3860 // | ^ \ / +------|---+
3861 // +->newloop \ \ / === ==cut | |
3862 // | stmt3 \ \ / TOP | |
3863 // | | dom | | stmt3 | | <-- first_not_peel
3864 // | v \ 1v v2 v | |
3865 // | ifB regionA ifB ^ v
3866 // | / \ | / \ | |
3867 // | / \ v / \ | |
3868 // | v v exitA: v v | |
3869 // | true false false true | |
3870 // | / ^ \ / \ | |
3871 // | | \ \ / v | |
3872 // | | dom \ / TOP | |
3873 // | | \ 1v v2 | |
3874 // ^ v regionB | |
3875 // | | | | |
3876 // | | v ^ v
3877 // | | exitB: | |
3878 // | | stmt4 | |
3879 // | +------------>-----------------+ |
3880 // | |
3881 // +-----------------<---------------------+
3882 //
3883 //
3884 // final graph
3885 //
3886 // stmt1
3887 // |
3888 // v
3889 // predicates
3890 // |
3891 // v
3892 // stmt2 clone
3893 // |
3894 // v
3895 // ........> ifA clone
3896 // : / |
3897 // dom / |
3898 // : v v
3899 // : false true
3900 // : | |
3901 // : | v
3902 // : | newloop<-----+
3903 // : | | |
3904 // : | stmt3 clone |
3905 // : | | |
3906 // : | v |
3907 // : | ifB |
3908 // : | / \ |
3909 // : | v v |
3910 // : | false true |
3911 // : | | | |
3912 // : | v stmt2 |
3913 // : | exitB: | |
3914 // : | stmt4 v |
3915 // : | ifA orig |
3916 // : | / \ |
3917 // : | / \ |
3918 // : | v v |
3919 // : | false true |
3920 // : | / \ |
3921 // : v v -----+
3922 // RegionA
3923 // |
3924 // v
3925 // exitA
3926 //
3927 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3928
3929 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3930 if (!loop->_head->is_Loop()) {
3931 return false;
3932 }
3933 LoopNode *head = loop->_head->as_Loop();
3934
3935 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3936 return false;
3937 }
3938
3939 // Check for complex exit control
3940 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3941 Node *n = loop->_body.at(ii);
3942 int opc = n->Opcode();
3943 if (n->is_Call() ||
3944 opc == Op_Catch ||
3945 opc == Op_CatchProj ||
3946 opc == Op_Jump ||
3947 opc == Op_JumpProj) {
3948 #ifndef PRODUCT
3949 if (TracePartialPeeling) {
3950 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3951 }
3952 #endif
3953 return false;
3954 }
3955 }
3956
3957 int dd = dom_depth(head);
3958
3959 // Step 1: find cut point
3960
3961 // Walk up dominators to loop head looking for first loop exit
3962 // which is executed on every path thru loop.
3963 IfNode *peel_if = nullptr;
3964 IfNode *peel_if_cmpu = nullptr;
3965
3966 Node *iff = loop->tail();
3967 while (iff != head) {
3968 if (iff->is_If()) {
3969 Node *ctrl = get_ctrl(iff->in(1));
3970 if (ctrl->is_top()) return false; // Dead test on live IF.
3971 // If loop-varying exit-test, check for induction variable
3972 if (loop->is_member(get_loop(ctrl)) &&
3973 loop->is_loop_exit(iff) &&
3974 is_possible_iv_test(iff)) {
3975 Node* cmp = iff->in(1)->in(1);
3976 if (cmp->Opcode() == Op_CmpI) {
3977 peel_if = iff->as_If();
3978 } else {
3979 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3980 peel_if_cmpu = iff->as_If();
3981 }
3982 }
3983 }
3984 iff = idom(iff);
3985 }
3986
3987 // Prefer signed compare over unsigned compare.
3988 IfNode* new_peel_if = nullptr;
3989 if (peel_if == nullptr) {
3990 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
3991 return false; // No peel point found
3992 }
3993 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3994 if (new_peel_if == nullptr) {
3995 return false; // No peel point found
3996 }
3997 peel_if = new_peel_if;
3998 }
3999 Node* last_peel = stay_in_loop(peel_if, loop);
4000 Node* first_not_peeled = stay_in_loop(last_peel, loop);
4001 if (first_not_peeled == nullptr || first_not_peeled == head) {
4002 return false;
4003 }
4004
4005 #ifndef PRODUCT
4006 if (TraceLoopOpts) {
4007 tty->print("PartialPeel ");
4008 loop->dump_head();
4009 }
4010
4011 if (TracePartialPeeling) {
4012 tty->print_cr("before partial peel one iteration");
4013 Node_List wl;
4014 Node* t = head->in(2);
4015 while (true) {
4016 wl.push(t);
4017 if (t == head) break;
4018 t = idom(t);
4019 }
4020 while (wl.size() > 0) {
4021 Node* tt = wl.pop();
4022 tt->dump();
4023 if (tt == last_peel) tty->print_cr("-- cut --");
4024 }
4025 }
4026 #endif
4027
4028 C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
4029
4030 VectorSet peel;
4031 VectorSet not_peel;
4032 Node_List peel_list;
4033 Node_List worklist;
4034 Node_List sink_list;
4035
4036 uint estimate = loop->est_loop_clone_sz(1);
4037 if (exceeding_node_budget(estimate)) {
4038 return false;
4039 }
4040
4041 // Set of cfg nodes to peel are those that are executable from
4042 // the head through last_peel.
4043 assert(worklist.size() == 0, "should be empty");
4044 worklist.push(head);
4045 peel.set(head->_idx);
4046 while (worklist.size() > 0) {
4047 Node *n = worklist.pop();
4048 if (n != last_peel) {
4049 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
4050 Node* use = n->fast_out(j);
4051 if (use->is_CFG() &&
4052 loop->is_member(get_loop(use)) &&
4053 !peel.test_set(use->_idx)) {
4054 worklist.push(use);
4055 }
4056 }
4057 }
4058 }
4059
4060 // Set of non-cfg nodes to peel are those that are control
4061 // dependent on the cfg nodes.
4062 for (uint i = 0; i < loop->_body.size(); i++) {
4063 Node *n = loop->_body.at(i);
4064 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
4065 if (peel.test(n_c->_idx)) {
4066 peel.set(n->_idx);
4067 } else {
4068 not_peel.set(n->_idx);
4069 }
4070 }
4071
4072 // Step 2: move operations from the peeled section down into the
4073 // not-peeled section
4074
4075 // Get a post order schedule of nodes in the peel region
4076 // Result in right-most operand.
4077 scheduled_nodelist(loop, peel, peel_list);
4078
4079 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4080
4081 // For future check for too many new phis
4082 uint old_phi_cnt = 0;
4083 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
4084 Node* use = head->fast_out(j);
4085 if (use->is_Phi()) old_phi_cnt++;
4086 }
4087
4088 #ifndef PRODUCT
4089 if (TracePartialPeeling) {
4090 tty->print_cr("\npeeled list");
4091 }
4092 #endif
4093
4094 // Evacuate nodes in peel region into the not_peeled region if possible
4095 bool too_many_clones = false;
4096 uint new_phi_cnt = 0;
4097 uint cloned_for_outside_use = 0;
4098 for (uint i = 0; i < peel_list.size();) {
4099 Node* n = peel_list.at(i);
4100 #ifndef PRODUCT
4101 if (TracePartialPeeling) n->dump();
4102 #endif
4103 bool incr = true;
4104 if (!n->is_CFG()) {
4105 if (has_use_in_set(n, not_peel)) {
4106 // If not used internal to the peeled region,
4107 // move "n" from peeled to not_peeled region.
4108 if (!has_use_internal_to_set(n, peel, loop)) {
4109 // if not pinned and not a load (which maybe anti-dependent on a store)
4110 // and not a CMove (Matcher expects only bool->cmove).
4111 if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
4112 int new_clones = clone_for_use_outside_loop(loop, n, worklist);
4113 if (C->failing()) return false;
4114 if (new_clones == -1) {
4115 too_many_clones = true;
4116 break;
4117 }
4118 cloned_for_outside_use += new_clones;
4119 sink_list.push(n);
4120 peel.remove(n->_idx);
4121 not_peel.set(n->_idx);
4122 peel_list.remove(i);
4123 incr = false;
4124 #ifndef PRODUCT
4125 if (TracePartialPeeling) {
4126 tty->print_cr("sink to not_peeled region: %d newbb: %d",
4127 n->_idx, get_ctrl(n)->_idx);
4128 }
4129 #endif
4130 }
4131 } else {
4132 // Otherwise check for special def-use cases that span
4133 // the peel/not_peel boundary such as bool->if
4134 clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
4135 new_phi_cnt++;
4136 }
4137 }
4138 }
4139 if (incr) i++;
4140 }
4141
4142 estimate += cloned_for_outside_use + new_phi_cnt;
4143 bool exceed_node_budget = !may_require_nodes(estimate);
4144 bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
4145
4146 if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
4147 #ifndef PRODUCT
4148 if (TracePartialPeeling && exceed_phi_limit) {
4149 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
4150 new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
4151 }
4152 #endif
4153 if (new_peel_if != nullptr) {
4154 remove_cmpi_loop_exit(new_peel_if, loop);
4155 }
4156 // Inhibit more partial peeling on this loop
4157 assert(!head->is_partial_peel_loop(), "not partial peeled");
4158 head->mark_partial_peel_failed();
4159 if (cloned_for_outside_use > 0) {
4160 // Terminate this round of loop opts because
4161 // the graph outside this loop was changed.
4162 C->set_major_progress();
4163 return true;
4164 }
4165 return false;
4166 }
4167
4168 // Step 3: clone loop, retarget control, and insert new phis
4169
4170 // Create new loop head for new phis and to hang
4171 // the nodes being moved (sinked) from the peel region.
4172 LoopNode* new_head = new LoopNode(last_peel, last_peel);
4173 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
4174 _igvn.register_new_node_with_optimizer(new_head);
4175 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
4176 _igvn.replace_input_of(first_not_peeled, 0, new_head);
4177 set_loop(new_head, loop);
4178 loop->_body.push(new_head);
4179 not_peel.set(new_head->_idx);
4180 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
4181 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
4182
4183 while (sink_list.size() > 0) {
4184 Node* n = sink_list.pop();
4185 set_ctrl(n, new_head);
4186 }
4187
4188 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4189
4190 clone_loop(loop, old_new, dd, IgnoreStripMined);
4191
4192 const uint clone_exit_idx = 1;
4193 const uint orig_exit_idx = 2;
4194 assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4195
4196 Node* head_clone = old_new[head->_idx];
4197 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
4198 Node* orig_tail_clone = head_clone->in(2);
4199
4200 // Add phi if "def" node is in peel set and "use" is not
4201
4202 for (uint i = 0; i < peel_list.size(); i++) {
4203 Node *def = peel_list.at(i);
4204 if (!def->is_CFG()) {
4205 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4206 Node *use = def->fast_out(j);
4207 if (has_node(use) && use->in(0) != C->top() &&
4208 (!peel.test(use->_idx) ||
4209 (use->is_Phi() && use->in(0) == head)) ) {
4210 worklist.push(use);
4211 }
4212 }
4213 while( worklist.size() ) {
4214 Node *use = worklist.pop();
4215 for (uint j = 1; j < use->req(); j++) {
4216 Node* n = use->in(j);
4217 if (n == def) {
4218
4219 // "def" is in peel set, "use" is not in peel set
4220 // or "use" is in the entry boundary (a phi) of the peel set
4221
4222 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4223
4224 if ( loop->is_member(get_loop( use_c )) ) {
4225 // use is in loop
4226 if (old_new[use->_idx] != nullptr) { // null for dead code
4227 Node* use_clone = old_new[use->_idx];
4228 _igvn.replace_input_of(use, j, C->top());
4229 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4230 }
4231 } else {
4232 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4233 // use is not in the loop, check if the live range includes the cut
4234 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4235 if (not_peel.test(lp_if->_idx)) {
4236 assert(j == orig_exit_idx, "use from original loop");
4237 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4238 }
4239 }
4240 }
4241 }
4242 }
4243 }
4244 }
4245
4246 // Step 3b: retarget control
4247
4248 // Redirect control to the new loop head if a cloned node in
4249 // the not_peeled region has control that points into the peeled region.
4250 // This necessary because the cloned peeled region will be outside
4251 // the loop.
4252 // from to
4253 // cloned-peeled <---+
4254 // new_head_clone: | <--+
4255 // cloned-not_peeled in(0) in(0)
4256 // orig-peeled
4257
4258 for (uint i = 0; i < loop->_body.size(); i++) {
4259 Node *n = loop->_body.at(i);
4260 if (!n->is_CFG() && n->in(0) != nullptr &&
4261 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4262 Node* n_clone = old_new[n->_idx];
4263 if (n_clone->depends_only_on_test()) {
4264 // Pin array access nodes: control is updated here to the loop head. If, after some transformations, the
4265 // backedge is removed, an array load could become dependent on a condition that's not a range check for that
4266 // access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
4267 // floating above its range check.
4268 Node* pinned_clone = n_clone->pin_array_access_node();
4269 if (pinned_clone != nullptr) {
4270 register_new_node_with_ctrl_of(pinned_clone, n_clone);
4271 old_new.map(n->_idx, pinned_clone);
4272 _igvn.replace_node(n_clone, pinned_clone);
4273 n_clone = pinned_clone;
4274 }
4275 }
4276 _igvn.replace_input_of(n_clone, 0, new_head_clone);
4277 }
4278 }
4279
4280 // Backedge of the surviving new_head (the clone) is original last_peel
4281 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4282
4283 // Cut first node in original not_peel set
4284 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
4285 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
4286 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
4287
4288 // Copy head_clone back-branch info to original head
4289 // and remove original head's loop entry and
4290 // clone head's back-branch
4291 _igvn.rehash_node_delayed(head); // Multiple edge updates
4292 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
4293 head->set_req(LoopNode::LoopBackControl, C->top());
4294 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4295
4296 // Similarly modify the phis
4297 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4298 Node* use = head->fast_out(k);
4299 if (use->is_Phi() && use->outcnt() > 0) {
4300 Node* use_clone = old_new[use->_idx];
4301 _igvn.rehash_node_delayed(use); // Multiple edge updates
4302 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
4303 use->set_req(LoopNode::LoopBackControl, C->top());
4304 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4305 }
4306 }
4307
4308 // Step 4: update dominator tree and dominator depth
4309
4310 set_idom(head, orig_tail_clone, dd);
4311 recompute_dom_depth();
4312
4313 // Inhibit more partial peeling on this loop
4314 new_head_clone->set_partial_peel_loop();
4315 C->set_major_progress();
4316 loop->record_for_igvn();
4317
4318 #ifndef PRODUCT
4319 if (TracePartialPeeling) {
4320 tty->print_cr("\nafter partial peel one iteration");
4321 Node_List wl;
4322 Node* t = last_peel;
4323 while (true) {
4324 wl.push(t);
4325 if (t == head_clone) break;
4326 t = idom(t);
4327 }
4328 while (wl.size() > 0) {
4329 Node* tt = wl.pop();
4330 if (tt == head) tty->print_cr("orig head");
4331 else if (tt == new_head_clone) tty->print_cr("new head");
4332 else if (tt == head_clone) tty->print_cr("clone head");
4333 tt->dump();
4334 }
4335 }
4336 #endif
4337
4338 C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4339
4340 return true;
4341 }
4342
4343 // Transform:
4344 //
4345 // loop<-----------------+
4346 // | |
4347 // stmt1 stmt2 .. stmtn |
4348 // | | | |
4349 // \ | / |
4350 // v v v |
4351 // region |
4352 // | |
4353 // shared_stmt |
4354 // | |
4355 // v |
4356 // if |
4357 // / \ |
4358 // | -----------+
4359 // v
4360 //
4361 // into:
4362 //
4363 // loop<-------------------+
4364 // | |
4365 // v |
4366 // +->loop |
4367 // | | |
4368 // | stmt1 stmt2 .. stmtn |
4369 // | | | | |
4370 // | | \ / |
4371 // | | v v |
4372 // | | region1 |
4373 // | | | |
4374 // | shared_stmt shared_stmt |
4375 // | | | |
4376 // | v v |
4377 // | if if |
4378 // | /\ / \ |
4379 // +-- | | -------+
4380 // \ /
4381 // v v
4382 // region2
4383 //
4384 // (region2 is shown to merge mirrored projections of the loop exit
4385 // ifs to make the diagram clearer but they really merge the same
4386 // projection)
4387 //
4388 // Conditions for this transformation to trigger:
4389 // - the path through stmt1 is frequent enough
4390 // - the inner loop will be turned into a counted loop after transformation
4391 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4392 if (!DuplicateBackedge) {
4393 return false;
4394 }
4395 assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4396 if (!loop->_head->is_Loop()) {
4397 return false;
4398 }
4399
4400 uint estimate = loop->est_loop_clone_sz(1);
4401 if (exceeding_node_budget(estimate)) {
4402 return false;
4403 }
4404
4405 LoopNode *head = loop->_head->as_Loop();
4406
4407 Node* region = nullptr;
4408 IfNode* exit_test = nullptr;
4409 uint inner;
4410 float f;
4411 if (StressDuplicateBackedge) {
4412 if (head->is_strip_mined()) {
4413 return false;
4414 }
4415 Node* c = head->in(LoopNode::LoopBackControl);
4416
4417 while (c != head) {
4418 if (c->is_Region()) {
4419 region = c;
4420 }
4421 c = idom(c);
4422 }
4423
4424 if (region == nullptr) {
4425 return false;
4426 }
4427
4428 inner = 1;
4429 } else {
4430 // Is the shape of the loop that of a counted loop...
4431 Node* back_control = loop_exit_control(head, loop);
4432 if (back_control == nullptr) {
4433 return false;
4434 }
4435
4436 BoolTest::mask bt = BoolTest::illegal;
4437 float cl_prob = 0;
4438 Node* incr = nullptr;
4439 Node* limit = nullptr;
4440 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4441 if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4442 return false;
4443 }
4444
4445 // With an extra phi for the candidate iv?
4446 // Or the region node is the loop head
4447 if (!incr->is_Phi() || incr->in(0) == head) {
4448 return false;
4449 }
4450
4451 PathFrequency pf(head, this);
4452 region = incr->in(0);
4453
4454 // Go over all paths for the extra phi's region and see if that
4455 // path is frequent enough and would match the expected iv shape
4456 // if the extra phi is removed
4457 inner = 0;
4458 for (uint i = 1; i < incr->req(); ++i) {
4459 Node* in = incr->in(i);
4460 Node* trunc1 = nullptr;
4461 Node* trunc2 = nullptr;
4462 const TypeInteger* iv_trunc_t = nullptr;
4463 Node* orig_in = in;
4464 if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4465 continue;
4466 }
4467 assert(in->Opcode() == Op_AddI, "wrong increment code");
4468 Node* xphi = nullptr;
4469 Node* stride = loop_iv_stride(in, loop, xphi);
4470
4471 if (stride == nullptr) {
4472 continue;
4473 }
4474
4475 PhiNode* phi = loop_iv_phi(xphi, nullptr, head, loop);
4476 if (phi == nullptr ||
4477 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4478 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4479 return false;
4480 }
4481
4482 f = pf.to(region->in(i));
4483 if (f > 0.5) {
4484 inner = i;
4485 break;
4486 }
4487 }
4488
4489 if (inner == 0) {
4490 return false;
4491 }
4492
4493 exit_test = back_control->in(0)->as_If();
4494 }
4495
4496 if (idom(region)->is_Catch()) {
4497 return false;
4498 }
4499
4500 // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4501 Unique_Node_List wq;
4502 wq.push(head->in(LoopNode::LoopBackControl));
4503 for (uint i = 0; i < wq.size(); i++) {
4504 Node* c = wq.at(i);
4505 assert(get_loop(c) == loop, "not in the right loop?");
4506 if (c->is_Region()) {
4507 if (c != region) {
4508 for (uint j = 1; j < c->req(); ++j) {
4509 wq.push(c->in(j));
4510 }
4511 }
4512 } else {
4513 wq.push(c->in(0));
4514 }
4515 assert(!is_strict_dominator(c, region), "shouldn't go above region");
4516 }
4517
4518 Node* region_dom = idom(region);
4519
4520 // Can't do the transformation if this would cause a membar pair to
4521 // be split
4522 for (uint i = 0; i < wq.size(); i++) {
4523 Node* c = wq.at(i);
4524 if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4525 assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4526 if (!wq.member(c->as_MemBar()->leading_membar())) {
4527 return false;
4528 }
4529 }
4530 }
4531
4532 // Collect data nodes that need to be clones as well
4533 int dd = dom_depth(head);
4534
4535 for (uint i = 0; i < loop->_body.size(); ++i) {
4536 Node* n = loop->_body.at(i);
4537 if (has_ctrl(n)) {
4538 Node* c = get_ctrl(n);
4539 if (wq.member(c)) {
4540 wq.push(n);
4541 }
4542 } else {
4543 set_idom(n, idom(n), dd);
4544 }
4545 }
4546
4547 // clone shared_stmt
4548 clone_loop_body(wq, old_new, nullptr);
4549
4550 Node* region_clone = old_new[region->_idx];
4551 region_clone->set_req(inner, C->top());
4552 set_idom(region, region->in(inner), dd);
4553
4554 // Prepare the outer loop
4555 Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4556 register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4557 _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4558 set_idom(head, outer_head, dd);
4559
4560 fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4561
4562 // Make one of the shared_stmt copies only reachable from stmt1, the
4563 // other only from stmt2..stmtn.
4564 Node* dom = nullptr;
4565 for (uint i = 1; i < region->req(); ++i) {
4566 if (i != inner) {
4567 _igvn.replace_input_of(region, i, C->top());
4568 }
4569 Node* in = region_clone->in(i);
4570 if (in->is_top()) {
4571 continue;
4572 }
4573 if (dom == nullptr) {
4574 dom = in;
4575 } else {
4576 dom = dom_lca(dom, in);
4577 }
4578 }
4579
4580 set_idom(region_clone, dom, dd);
4581
4582 // Set up the outer loop
4583 for (uint i = 0; i < head->outcnt(); i++) {
4584 Node* u = head->raw_out(i);
4585 if (u->is_Phi()) {
4586 Node* outer_phi = u->clone();
4587 outer_phi->set_req(0, outer_head);
4588 Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4589 if (backedge == nullptr) {
4590 backedge = u->in(LoopNode::LoopBackControl);
4591 }
4592 outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4593 register_new_node(outer_phi, outer_head);
4594 _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4595 }
4596 }
4597
4598 // create control and data nodes for out of loop uses (including region2)
4599 Node_List worklist;
4600 uint new_counter = C->unique();
4601 fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4602
4603 Node_List *split_if_set = nullptr;
4604 Node_List *split_bool_set = nullptr;
4605 Node_List *split_cex_set = nullptr;
4606 fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4607 split_if_set, split_bool_set, split_cex_set);
4608
4609 finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4610
4611 if (exit_test != nullptr) {
4612 float cnt = exit_test->_fcnt;
4613 if (cnt != COUNT_UNKNOWN) {
4614 exit_test->_fcnt = cnt * f;
4615 old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4616 }
4617 }
4618
4619 C->set_major_progress();
4620
4621 return true;
4622 }
4623
4624 // AutoVectorize the loop: replace scalar ops with vector ops.
4625 PhaseIdealLoop::AutoVectorizeStatus
4626 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4627 // Counted loop only
4628 if (!lpt->is_counted()) {
4629 return AutoVectorizeStatus::Impossible;
4630 }
4631
4632 // Main-loop only
4633 CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4634 if (!cl->is_main_loop()) {
4635 return AutoVectorizeStatus::Impossible;
4636 }
4637
4638 VLoop vloop(lpt, false);
4639 if (!vloop.check_preconditions()) {
4640 return AutoVectorizeStatus::TriedAndFailed;
4641 }
4642
4643 // Ensure the shared data is cleared before each use
4644 vshared.clear();
4645
4646 const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4647 if (!vloop_analyzer.success()) {
4648 return AutoVectorizeStatus::TriedAndFailed;
4649 }
4650
4651 SuperWord sw(vloop_analyzer);
4652 if (!sw.transform_loop()) {
4653 return AutoVectorizeStatus::TriedAndFailed;
4654 }
4655
4656 return AutoVectorizeStatus::Success;
4657 }
4658
4659 // Returns true if the Reduction node is unordered.
4660 static bool is_unordered_reduction(Node* n) {
4661 return n->is_Reduction() && !n->as_Reduction()->requires_strict_order();
4662 }
4663
4664 // Having ReductionNodes in the loop is expensive. They need to recursively
4665 // fold together the vector values, for every vectorized loop iteration. If
4666 // we encounter the following pattern, we can vector accumulate the values
4667 // inside the loop, and only have a single UnorderedReduction after the loop.
4668 //
4669 // Note: UnorderedReduction represents a ReductionNode which does not require
4670 // calculating in strict order.
4671 //
4672 // CountedLoop init
4673 // | |
4674 // +------+ | +-----------------------+
4675 // | | | |
4676 // PhiNode (s) |
4677 // | |
4678 // | Vector |
4679 // | | |
4680 // UnorderedReduction (first_ur) |
4681 // | |
4682 // ... Vector |
4683 // | | |
4684 // UnorderedReduction (last_ur) |
4685 // | |
4686 // +---------------------+
4687 //
4688 // We patch the graph to look like this:
4689 //
4690 // CountedLoop identity_vector
4691 // | |
4692 // +-------+ | +---------------+
4693 // | | | |
4694 // PhiNode (v) |
4695 // | |
4696 // | Vector |
4697 // | | |
4698 // VectorAccumulator |
4699 // | |
4700 // ... Vector |
4701 // | | |
4702 // init VectorAccumulator |
4703 // | | | |
4704 // UnorderedReduction +-----------+
4705 //
4706 // We turned the scalar (s) Phi into a vectorized one (v). In the loop, we
4707 // use vector_accumulators, which do the same reductions, but only element
4708 // wise. This is a single operation per vector_accumulator, rather than many
4709 // for a UnorderedReduction. We can then reduce the last vector_accumulator
4710 // after the loop, and also reduce the init value into it.
4711 //
4712 // We can not do this with all reductions. Some reductions do not allow the
4713 // reordering of operations (for example float addition/multiplication require
4714 // strict order).
4715 void PhaseIdealLoop::move_unordered_reduction_out_of_loop(IdealLoopTree* loop) {
4716 assert(!C->major_progress() && loop->is_counted() && loop->is_innermost(), "sanity");
4717
4718 // Find all Phi nodes with an unordered Reduction on backedge.
4719 CountedLoopNode* cl = loop->_head->as_CountedLoop();
4720 for (DUIterator_Fast jmax, j = cl->fast_outs(jmax); j < jmax; j++) {
4721 Node* phi = cl->fast_out(j);
4722 // We have a phi with a single use, and an unordered Reduction on the backedge.
4723 if (!phi->is_Phi() || phi->outcnt() != 1 || !is_unordered_reduction(phi->in(2))) {
4724 continue;
4725 }
4726
4727 ReductionNode* last_ur = phi->in(2)->as_Reduction();
4728 assert(!last_ur->requires_strict_order(), "must be");
4729
4730 // Determine types
4731 const TypeVect* vec_t = last_ur->vect_type();
4732 uint vector_length = vec_t->length();
4733 BasicType bt = vec_t->element_basic_type();
4734
4735 // Convert opcode from vector-reduction -> scalar -> normal-vector-op
4736 const int sopc = VectorNode::scalar_opcode(last_ur->Opcode(), bt);
4737 const int vopc = VectorNode::opcode(sopc, bt);
4738 if (!Matcher::match_rule_supported_vector(vopc, vector_length, bt)) {
4739 DEBUG_ONLY( last_ur->dump(); )
4740 assert(false, "do not have normal vector op for this reduction");
4741 continue; // not implemented -> fails
4742 }
4743
4744 // Traverse up the chain of unordered Reductions, checking that it loops back to
4745 // the phi. Check that all unordered Reductions only have a single use, except for
4746 // the last (last_ur), which only has phi as a use in the loop, and all other uses
4747 // are outside the loop.
4748 ReductionNode* current = last_ur;
4749 ReductionNode* first_ur = nullptr;
4750 while (true) {
4751 assert(!current->requires_strict_order(), "sanity");
4752
4753 // Expect no ctrl and a vector_input from within the loop.
4754 Node* ctrl = current->in(0);
4755 Node* vector_input = current->in(2);
4756 if (ctrl != nullptr || get_ctrl(vector_input) != cl) {
4757 DEBUG_ONLY( current->dump(1); )
4758 assert(false, "reduction has ctrl or bad vector_input");
4759 break; // Chain traversal fails.
4760 }
4761
4762 assert(current->vect_type() != nullptr, "must have vector type");
4763 if (current->vect_type() != last_ur->vect_type()) {
4764 // Reductions do not have the same vector type (length and element type).
4765 break; // Chain traversal fails.
4766 }
4767
4768 // Expect single use of an unordered Reduction, except for last_ur.
4769 if (current == last_ur) {
4770 // Expect all uses to be outside the loop, except phi.
4771 for (DUIterator_Fast kmax, k = current->fast_outs(kmax); k < kmax; k++) {
4772 Node* use = current->fast_out(k);
4773 if (use != phi && ctrl_or_self(use) == cl) {
4774 DEBUG_ONLY( current->dump(-1); )
4775 assert(false, "reduction has use inside loop");
4776 // Should not be allowed by SuperWord::mark_reductions
4777 return; // bail out of optimization
4778 }
4779 }
4780 } else {
4781 if (current->outcnt() != 1) {
4782 break; // Chain traversal fails.
4783 }
4784 }
4785
4786 // Expect another unordered Reduction or phi as the scalar input.
4787 Node* scalar_input = current->in(1);
4788 if (is_unordered_reduction(scalar_input) &&
4789 scalar_input->Opcode() == current->Opcode()) {
4790 // Move up the unordered Reduction chain.
4791 current = scalar_input->as_Reduction();
4792 assert(!current->requires_strict_order(), "must be");
4793 } else if (scalar_input == phi) {
4794 // Chain terminates at phi.
4795 first_ur = current;
4796 current = nullptr;
4797 break; // Success.
4798 } else {
4799 // scalar_input is neither phi nor a matching reduction
4800 // Can for example be scalar reduction when we have
4801 // partial vectorization.
4802 break; // Chain traversal fails.
4803 }
4804 }
4805 if (current != nullptr) {
4806 // Chain traversal was not successful.
4807 continue;
4808 }
4809 assert(first_ur != nullptr, "must have successfully terminated chain traversal");
4810
4811 Node* identity_scalar = ReductionNode::make_identity_con_scalar(_igvn, sopc, bt);
4812 set_ctrl(identity_scalar, C->root());
4813 VectorNode* identity_vector = VectorNode::scalar2vector(identity_scalar, vector_length, bt);
4814 register_new_node(identity_vector, C->root());
4815 assert(vec_t == identity_vector->vect_type(), "matching vector type");
4816 VectorNode::trace_new_vector(identity_vector, "Unordered Reduction");
4817
4818 // Turn the scalar phi into a vector phi.
4819 _igvn.rehash_node_delayed(phi);
4820 Node* init = phi->in(1); // Remember init before replacing it.
4821 phi->set_req_X(1, identity_vector, &_igvn);
4822 phi->as_Type()->set_type(vec_t);
4823 _igvn.set_type(phi, vec_t);
4824
4825 // Traverse down the chain of unordered Reductions, and replace them with vector_accumulators.
4826 current = first_ur;
4827 while (true) {
4828 // Create vector_accumulator to replace current.
4829 Node* last_vector_accumulator = current->in(1);
4830 Node* vector_input = current->in(2);
4831 VectorNode* vector_accumulator = VectorNode::make(vopc, last_vector_accumulator, vector_input, vec_t);
4832 register_new_node(vector_accumulator, cl);
4833 _igvn.replace_node(current, vector_accumulator);
4834 VectorNode::trace_new_vector(vector_accumulator, "Unordered Reduction");
4835 if (current == last_ur) {
4836 break;
4837 }
4838 current = vector_accumulator->unique_out()->as_Reduction();
4839 assert(!current->requires_strict_order(), "must be");
4840 }
4841
4842 // Create post-loop reduction.
4843 Node* last_accumulator = phi->in(2);
4844 Node* post_loop_reduction = ReductionNode::make(sopc, nullptr, init, last_accumulator, bt);
4845
4846 // Take over uses of last_accumulator that are not in the loop.
4847 for (DUIterator i = last_accumulator->outs(); last_accumulator->has_out(i); i++) {
4848 Node* use = last_accumulator->out(i);
4849 if (use != phi && use != post_loop_reduction) {
4850 assert(ctrl_or_self(use) != cl, "use must be outside loop");
4851 use->replace_edge(last_accumulator, post_loop_reduction, &_igvn);
4852 --i;
4853 }
4854 }
4855 register_new_node(post_loop_reduction, get_late_ctrl(post_loop_reduction, cl));
4856 VectorNode::trace_new_vector(post_loop_reduction, "Unordered Reduction");
4857
4858 assert(last_accumulator->outcnt() == 2, "last_accumulator has 2 uses: phi and post_loop_reduction");
4859 assert(post_loop_reduction->outcnt() > 0, "should have taken over all non loop uses of last_accumulator");
4860 assert(phi->outcnt() == 1, "accumulator is the only use of phi");
4861 }
4862 }
4863
4864 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4865 for (uint i = 0; i < _data_nodes.size(); i++) {
4866 clone(_data_nodes[i], new_ctrl);
4867 }
4868 }
4869
4870 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4871 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4872 Node* clone = node->clone();
4873 _phase->igvn().register_new_node_with_optimizer(clone);
4874 _orig_to_new.put(node, clone);
4875 _phase->set_ctrl(clone, new_ctrl);
4876 if (node->is_CastII()) {
4877 clone->set_req(0, new_ctrl);
4878 }
4879 }
4880
4881 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4882 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4883 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4884 _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4885 for (uint i = 1; i < node->req(); i++) {
4886 Node** cloned_input = _orig_to_new.get(node->in(i));
4887 if (cloned_input != nullptr) {
4888 // Input was also cloned -> rewire clone to the cloned input.
4889 _phase->igvn().replace_input_of(clone, i, *cloned_input);
4890 }
4891 }
4892 });
4893 }
4894
4895 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4896 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4897 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4898 const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4899 Node* new_ctrl) {
4900 for (uint i = 0; i < _data_nodes.size(); i++) {
4901 Node* data_node = _data_nodes[i];
4902 if (data_node->is_Opaque1()) {
4903 transform_opaque_node(transform_strategy, data_node);
4904 } else {
4905 clone(data_node, new_ctrl);
4906 }
4907 }
4908 }
4909
4910 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4911 Node* transformed_node;
4912 if (node->is_OpaqueLoopInit()) {
4913 transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4914 } else {
4915 assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4916 transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4917 }
4918 // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4919 _orig_to_new.put(node, transformed_node);
4920 }