1 /*
2 * Copyright (c) 1999, 2019, 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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
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/loopnode.hpp"
37 #include "opto/matcher.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/movenode.hpp"
40 #include "opto/opaquenode.hpp"
41 #include "opto/rootnode.hpp"
42 #include "opto/subnode.hpp"
43 #include "utilities/macros.hpp"
44
45 //=============================================================================
46 //------------------------------split_thru_phi---------------------------------
47 // Split Node 'n' through merge point if there is enough win.
48 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
49 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
50 // ConvI2L may have type information on it which is unsafe to push up
51 // so disable this for now
52 return NULL;
53 }
54
55 // Splitting range check CastIIs through a loop induction Phi can
56 // cause new Phis to be created that are left unrelated to the loop
57 // induction Phi and prevent optimizations (vectorization)
58 if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
59 region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
60 return NULL;
61 }
62
63 int wins = 0;
64 assert(!n->is_CFG(), "");
65 assert(region->is_Region(), "");
66
67 const Type* type = n->bottom_type();
68 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
69 Node *phi;
70 if (t_oop != NULL && t_oop->is_known_instance_field()) {
71 int iid = t_oop->instance_id();
72 int index = C->get_alias_index(t_oop);
73 int offset = t_oop->offset();
74 phi = new PhiNode(region, type, NULL, iid, index, offset);
75 } else {
76 phi = PhiNode::make_blank(region, n);
77 }
78 uint old_unique = C->unique();
79 for (uint i = 1; i < region->req(); i++) {
80 Node *x;
81 Node* the_clone = NULL;
82 if (region->in(i) == C->top()) {
83 x = C->top(); // Dead path? Use a dead data op
84 } else {
85 x = n->clone(); // Else clone up the data op
86 the_clone = x; // Remember for possible deletion.
87 // Alter data node to use pre-phi inputs
88 if (n->in(0) == region)
89 x->set_req( 0, region->in(i) );
90 for (uint j = 1; j < n->req(); j++) {
91 Node *in = n->in(j);
92 if (in->is_Phi() && in->in(0) == region)
93 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
94 }
95 }
96 // Check for a 'win' on some paths
97 const Type *t = x->Value(&_igvn);
98
99 bool singleton = t->singleton();
100
101 // A TOP singleton indicates that there are no possible values incoming
102 // along a particular edge. In most cases, this is OK, and the Phi will
103 // be eliminated later in an Ideal call. However, we can't allow this to
104 // happen if the singleton occurs on loop entry, as the elimination of
105 // the PhiNode may cause the resulting node to migrate back to a previous
106 // loop iteration.
107 if (singleton && t == Type::TOP) {
108 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
109 // irreducible loop may not be indicated by an affirmative is_Loop());
110 // therefore, the only top we can split thru a phi is on a backedge of
111 // a loop.
112 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
113 }
114
115 if (singleton) {
116 wins++;
117 x = ((PhaseGVN&)_igvn).makecon(t);
118 } else {
119 // We now call Identity to try to simplify the cloned node.
120 // Note that some Identity methods call phase->type(this).
121 // Make sure that the type array is big enough for
122 // our new node, even though we may throw the node away.
123 // (Note: This tweaking with igvn only works because x is a new node.)
124 _igvn.set_type(x, t);
125 // If x is a TypeNode, capture any more-precise type permanently into Node
126 // otherwise it will be not updated during igvn->transform since
127 // igvn->type(x) is set to x->Value() already.
128 x->raise_bottom_type(t);
129 Node *y = _igvn.apply_identity(x);
130 if (y != x) {
131 wins++;
132 x = y;
133 } else {
134 y = _igvn.hash_find(x);
135 if (y) {
136 wins++;
137 x = y;
138 } else {
139 // Else x is a new node we are keeping
140 // We do not need register_new_node_with_optimizer
141 // because set_type has already been called.
142 _igvn._worklist.push(x);
143 }
144 }
145 }
146 if (x != the_clone && the_clone != NULL)
147 _igvn.remove_dead_node(the_clone);
148 phi->set_req( i, x );
149 }
150 // Too few wins?
151 if (wins <= policy) {
152 _igvn.remove_dead_node(phi);
153 return NULL;
154 }
155
156 // Record Phi
157 register_new_node( phi, region );
158
159 for (uint i2 = 1; i2 < phi->req(); i2++) {
160 Node *x = phi->in(i2);
161 // If we commoned up the cloned 'x' with another existing Node,
162 // the existing Node picks up a new use. We need to make the
163 // existing Node occur higher up so it dominates its uses.
164 Node *old_ctrl;
165 IdealLoopTree *old_loop;
166
167 if (x->is_Con()) {
168 // Constant's control is always root.
169 set_ctrl(x, C->root());
170 continue;
171 }
172 // The occasional new node
173 if (x->_idx >= old_unique) { // Found a new, unplaced node?
174 old_ctrl = NULL;
175 old_loop = NULL; // Not in any prior loop
176 } else {
177 old_ctrl = get_ctrl(x);
178 old_loop = get_loop(old_ctrl); // Get prior loop
179 }
180 // New late point must dominate new use
181 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
182 if (new_ctrl == old_ctrl) // Nothing is changed
183 continue;
184
185 IdealLoopTree *new_loop = get_loop(new_ctrl);
186
187 // Don't move x into a loop if its uses are
188 // outside of loop. Otherwise x will be cloned
189 // for each use outside of this loop.
190 IdealLoopTree *use_loop = get_loop(region);
191 if (!new_loop->is_member(use_loop) &&
192 (old_loop == NULL || !new_loop->is_member(old_loop))) {
193 // Take early control, later control will be recalculated
194 // during next iteration of loop optimizations.
195 new_ctrl = get_early_ctrl(x);
196 new_loop = get_loop(new_ctrl);
197 }
198 // Set new location
199 set_ctrl(x, new_ctrl);
200 // If changing loop bodies, see if we need to collect into new body
201 if (old_loop != new_loop) {
202 if (old_loop && !old_loop->_child)
203 old_loop->_body.yank(x);
204 if (!new_loop->_child)
205 new_loop->_body.push(x); // Collect body info
206 }
207 }
208
209 return phi;
210 }
211
212 //------------------------------dominated_by------------------------------------
213 // Replace the dominated test with an obvious true or false. Place it on the
214 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
215 // live path up to the dominating control.
216 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
217 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
218
219 // prevdom is the dominating projection of the dominating test.
220 assert( iff->is_If(), "" );
221 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
222 int pop = prevdom->Opcode();
223 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
224 if (flip) {
225 if (pop == Op_IfTrue)
226 pop = Op_IfFalse;
227 else
228 pop = Op_IfTrue;
229 }
230 // 'con' is set to true or false to kill the dominated test.
231 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
232 set_ctrl(con, C->root()); // Constant gets a new use
233 // Hack the dominated test
234 _igvn.replace_input_of(iff, 1, con);
235
236 // If I dont have a reachable TRUE and FALSE path following the IfNode then
237 // I can assume this path reaches an infinite loop. In this case it's not
238 // important to optimize the data Nodes - either the whole compilation will
239 // be tossed or this path (and all data Nodes) will go dead.
240 if (iff->outcnt() != 2) return;
241
242 // Make control-dependent data Nodes on the live path (path that will remain
243 // once the dominated IF is removed) become control-dependent on the
244 // dominating projection.
245 Node* dp = iff->as_If()->proj_out_or_null(pop == Op_IfTrue);
246
247 // Loop predicates may have depending checks which should not
248 // be skipped. For example, range check predicate has two checks
249 // for lower and upper bounds.
250 if (dp == NULL)
251 return;
252
253 ProjNode* dp_proj = dp->as_Proj();
254 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
255 if (exclude_loop_predicate &&
256 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
257 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL ||
258 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
259 // If this is a range check (IfNode::is_range_check), do not
260 // reorder because Compile::allow_range_check_smearing might have
261 // changed the check.
262 return; // Let IGVN transformation change control dependence.
263 }
264
265 IdealLoopTree *old_loop = get_loop(dp);
266
267 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
268 Node* cd = dp->fast_out(i); // Control-dependent node
269 if (cd->depends_only_on_test()) {
270 assert(cd->in(0) == dp, "");
271 _igvn.replace_input_of(cd, 0, prevdom);
272 set_early_ctrl(cd);
273 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
274 if (old_loop != new_loop) {
275 if (!old_loop->_child) old_loop->_body.yank(cd);
276 if (!new_loop->_child) new_loop->_body.push(cd);
277 }
278 --i;
279 --imax;
280 }
281 }
282 }
283
284 //------------------------------has_local_phi_input----------------------------
285 // Return TRUE if 'n' has Phi inputs from its local block and no other
286 // block-local inputs (all non-local-phi inputs come from earlier blocks)
287 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
288 Node *n_ctrl = get_ctrl(n);
289 // See if some inputs come from a Phi in this block, or from before
290 // this block.
291 uint i;
292 for( i = 1; i < n->req(); i++ ) {
293 Node *phi = n->in(i);
294 if( phi->is_Phi() && phi->in(0) == n_ctrl )
295 break;
296 }
297 if( i >= n->req() )
298 return NULL; // No Phi inputs; nowhere to clone thru
299
300 // Check for inputs created between 'n' and the Phi input. These
301 // must split as well; they have already been given the chance
302 // (courtesy of a post-order visit) and since they did not we must
303 // recover the 'cost' of splitting them by being very profitable
304 // when splitting 'n'. Since this is unlikely we simply give up.
305 for( i = 1; i < n->req(); i++ ) {
306 Node *m = n->in(i);
307 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
308 // We allow the special case of AddP's with no local inputs.
309 // This allows us to split-up address expressions.
310 if (m->is_AddP() &&
311 get_ctrl(m->in(2)) != n_ctrl &&
312 get_ctrl(m->in(3)) != n_ctrl) {
313 // Move the AddP up to dominating point
314 Node* c = find_non_split_ctrl(idom(n_ctrl));
315 if (c->is_OuterStripMinedLoop()) {
316 c->as_Loop()->verify_strip_mined(1);
317 c = c->in(LoopNode::EntryControl);
318 }
319 set_ctrl_and_loop(m, c);
320 continue;
321 }
322 return NULL;
323 }
324 assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
325 }
326
327 return n_ctrl;
328 }
329
330 //------------------------------remix_address_expressions----------------------
331 // Rework addressing expressions to get the most loop-invariant stuff
332 // moved out. We'd like to do all associative operators, but it's especially
333 // important (common) to do address expressions.
334 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
335 if (!has_ctrl(n)) return NULL;
336 Node *n_ctrl = get_ctrl(n);
337 IdealLoopTree *n_loop = get_loop(n_ctrl);
338
339 // See if 'n' mixes loop-varying and loop-invariant inputs and
340 // itself is loop-varying.
341
342 // Only interested in binary ops (and AddP)
343 if( n->req() < 3 || n->req() > 4 ) return NULL;
344
345 Node *n1_ctrl = get_ctrl(n->in( 1));
346 Node *n2_ctrl = get_ctrl(n->in( 2));
347 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
348 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
349 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
350 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
351
352 // Does one of my inputs spin in a tighter loop than self?
353 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
354 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
355 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
356 return NULL; // Leave well enough alone
357
358 // Is at least one of my inputs loop-invariant?
359 if( n1_loop == n_loop &&
360 n2_loop == n_loop &&
361 n3_loop == n_loop )
362 return NULL; // No loop-invariant inputs
363
364
365 int n_op = n->Opcode();
366
367 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
368 if( n_op == Op_LShiftI ) {
369 // Scale is loop invariant
370 Node *scale = n->in(2);
371 Node *scale_ctrl = get_ctrl(scale);
372 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
373 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
374 return NULL;
375 const TypeInt *scale_t = scale->bottom_type()->isa_int();
376 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
377 return NULL; // Dont bother with byte/short masking
378 // Add must vary with loop (else shift would be loop-invariant)
379 Node *add = n->in(1);
380 Node *add_ctrl = get_ctrl(add);
381 IdealLoopTree *add_loop = get_loop(add_ctrl);
382 //assert( n_loop == add_loop, "" );
383 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
384
385 // Convert I-V into I+ (0-V); same for V-I
386 if( add->Opcode() == Op_SubI &&
387 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
388 Node *zero = _igvn.intcon(0);
389 set_ctrl(zero, C->root());
390 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
391 register_new_node( neg, get_ctrl(add->in(2) ) );
392 add = new AddINode( add->in(1), neg );
393 register_new_node( add, add_ctrl );
394 }
395 if( add->Opcode() != Op_AddI ) return NULL;
396 // See if one add input is loop invariant
397 Node *add_var = add->in(1);
398 Node *add_var_ctrl = get_ctrl(add_var);
399 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
400 Node *add_invar = add->in(2);
401 Node *add_invar_ctrl = get_ctrl(add_invar);
402 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
403 if( add_var_loop == n_loop ) {
404 } else if( add_invar_loop == n_loop ) {
405 // Swap to find the invariant part
406 add_invar = add_var;
407 add_invar_ctrl = add_var_ctrl;
408 add_invar_loop = add_var_loop;
409 add_var = add->in(2);
410 Node *add_var_ctrl = get_ctrl(add_var);
411 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
412 } else // Else neither input is loop invariant
413 return NULL;
414 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
415 return NULL; // No invariant part of the add?
416
417 // Yes! Reshape address expression!
418 Node *inv_scale = new LShiftINode( add_invar, scale );
419 Node *inv_scale_ctrl =
420 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
421 add_invar_ctrl : scale_ctrl;
422 register_new_node( inv_scale, inv_scale_ctrl );
423 Node *var_scale = new LShiftINode( add_var, scale );
424 register_new_node( var_scale, n_ctrl );
425 Node *var_add = new AddINode( var_scale, inv_scale );
426 register_new_node( var_add, n_ctrl );
427 _igvn.replace_node( n, var_add );
428 return var_add;
429 }
430
431 // Replace (I+V) with (V+I)
432 if( n_op == Op_AddI ||
433 n_op == Op_AddL ||
434 n_op == Op_AddF ||
435 n_op == Op_AddD ||
436 n_op == Op_MulI ||
437 n_op == Op_MulL ||
438 n_op == Op_MulF ||
439 n_op == Op_MulD ) {
440 if( n2_loop == n_loop ) {
441 assert( n1_loop != n_loop, "" );
442 n->swap_edges(1, 2);
443 }
444 }
445
446 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
447 // but not if I2 is a constant.
448 if( n_op == Op_AddP ) {
449 if( n2_loop == n_loop && n3_loop != n_loop ) {
450 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
451 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
452 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
453 IdealLoopTree *n22loop = get_loop( n22_ctrl );
454 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
455 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
456 n23_loop == n_loop ) {
457 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
458 // Stuff new AddP in the loop preheader
459 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
460 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
461 register_new_node( add2, n_ctrl );
462 _igvn.replace_node( n, add2 );
463 return add2;
464 }
465 }
466 }
467
468 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
469 if (n2_loop != n_loop && n3_loop == n_loop) {
470 if (n->in(3)->Opcode() == Op_AddX) {
471 Node *V = n->in(3)->in(1);
472 Node *I = n->in(3)->in(2);
473 if (is_member(n_loop,get_ctrl(V))) {
474 } else {
475 Node *tmp = V; V = I; I = tmp;
476 }
477 if (!is_member(n_loop,get_ctrl(I))) {
478 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
479 // Stuff new AddP in the loop preheader
480 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
481 Node *add2 = new AddPNode(n->in(1), add1, V);
482 register_new_node(add2, n_ctrl);
483 _igvn.replace_node(n, add2);
484 return add2;
485 }
486 }
487 }
488 }
489
490 return NULL;
491 }
492
493 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
494 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
495 assert(n->Opcode() == Op_AddI, "sanity");
496 Node * nn = NULL;
497 Node * in1 = n->in(1);
498 Node * in2 = n->in(2);
499 if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
500 IdealLoopTree* loop_n = get_loop(get_ctrl(n));
501 if (loop_n->_head->as_Loop()->is_valid_counted_loop() &&
502 Matcher::match_rule_supported(Op_MulAddS2I) &&
503 Matcher::match_rule_supported(Op_MulAddVS2VI)) {
504 Node* mul_in1 = in1->in(1);
505 Node* mul_in2 = in1->in(2);
506 Node* mul_in3 = in2->in(1);
507 Node* mul_in4 = in2->in(2);
508 if (mul_in1->Opcode() == Op_LoadS &&
509 mul_in2->Opcode() == Op_LoadS &&
510 mul_in3->Opcode() == Op_LoadS &&
511 mul_in4->Opcode() == Op_LoadS) {
512 IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
513 IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
514 IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
515 IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
516 IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
517 IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
518 // All nodes should be in the same counted loop.
519 if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
520 loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
521 Node* adr1 = mul_in1->in(MemNode::Address);
522 Node* adr2 = mul_in2->in(MemNode::Address);
523 Node* adr3 = mul_in3->in(MemNode::Address);
524 Node* adr4 = mul_in4->in(MemNode::Address);
525 if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
526 if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
527 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
528 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
529 register_new_node(nn, get_ctrl(n));
530 _igvn.replace_node(n, nn);
531 return nn;
532 } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
533 (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
534 nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
535 register_new_node(nn, get_ctrl(n));
536 _igvn.replace_node(n, nn);
537 return nn;
538 }
539 }
540 }
541 }
542 }
543 }
544 return nn;
545 }
546
547 //------------------------------conditional_move-------------------------------
548 // Attempt to replace a Phi with a conditional move. We have some pretty
549 // strict profitability requirements. All Phis at the merge point must
550 // be converted, so we can remove the control flow. We need to limit the
551 // number of c-moves to a small handful. All code that was in the side-arms
552 // of the CFG diamond is now speculatively executed. This code has to be
553 // "cheap enough". We are pretty much limited to CFG diamonds that merge
554 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
555 Node *PhaseIdealLoop::conditional_move( Node *region ) {
556
557 assert(region->is_Region(), "sanity check");
558 if (region->req() != 3) return NULL;
559
560 // Check for CFG diamond
561 Node *lp = region->in(1);
562 Node *rp = region->in(2);
563 if (!lp || !rp) return NULL;
564 Node *lp_c = lp->in(0);
565 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
566 IfNode *iff = lp_c->as_If();
567
568 // Check for ops pinned in an arm of the diamond.
569 // Can't remove the control flow in this case
570 if (lp->outcnt() > 1) return NULL;
571 if (rp->outcnt() > 1) return NULL;
572
573 IdealLoopTree* r_loop = get_loop(region);
574 assert(r_loop == get_loop(iff), "sanity");
575 // Always convert to CMOVE if all results are used only outside this loop.
576 bool used_inside_loop = (r_loop == _ltree_root);
577
578 // Check profitability
579 int cost = 0;
580 int phis = 0;
581 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
582 Node *out = region->fast_out(i);
583 if (!out->is_Phi()) continue; // Ignore other control edges, etc
584 phis++;
585 PhiNode* phi = out->as_Phi();
586 BasicType bt = phi->type()->basic_type();
587 switch (bt) {
588 case T_DOUBLE:
589 case T_FLOAT:
590 if (C->use_cmove()) {
591 continue; //TODO: maybe we want to add some cost
592 }
593 cost += Matcher::float_cmove_cost(); // Could be very expensive
594 break;
595 case T_LONG: {
596 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
597 }
598 case T_INT: // These all CMOV fine
599 case T_ADDRESS: { // (RawPtr)
600 cost++;
601 break;
602 }
603 case T_NARROWOOP: // Fall through
604 case T_OBJECT: { // Base oops are OK, but not derived oops
605 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
606 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
607 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
608 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
609 // have a Phi for the base here that we convert to a CMOVE all is well
610 // and good. But if the base is dead, we'll not make a CMOVE. Later
611 // the allocator will have to produce a base by creating a CMOVE of the
612 // relevant bases. This puts the allocator in the business of
613 // manufacturing expensive instructions, generally a bad plan.
614 // Just Say No to Conditionally-Moved Derived Pointers.
615 if (tp && tp->offset() != 0)
616 return NULL;
617 cost++;
618 break;
619 }
620 default:
621 return NULL; // In particular, can't do memory or I/O
622 }
623 // Add in cost any speculative ops
624 for (uint j = 1; j < region->req(); j++) {
625 Node *proj = region->in(j);
626 Node *inp = phi->in(j);
627 if (get_ctrl(inp) == proj) { // Found local op
628 cost++;
629 // Check for a chain of dependent ops; these will all become
630 // speculative in a CMOV.
631 for (uint k = 1; k < inp->req(); k++)
632 if (get_ctrl(inp->in(k)) == proj)
633 cost += ConditionalMoveLimit; // Too much speculative goo
634 }
635 }
636 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
637 // This will likely Split-If, a higher-payoff operation.
638 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
639 Node* use = phi->fast_out(k);
640 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
641 cost += ConditionalMoveLimit;
642 // Is there a use inside the loop?
643 // Note: check only basic types since CMoveP is pinned.
644 if (!used_inside_loop && is_java_primitive(bt)) {
645 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
646 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
647 used_inside_loop = true;
648 }
649 }
650 }
651 }//for
652 Node* bol = iff->in(1);
653 if (bol->Opcode() == Op_Opaque4) {
654 return NULL; // Ignore loop predicate checks (the Opaque4 ensures they will go away)
655 }
656 assert(bol->Opcode() == Op_Bool, "Unexpected node");
657 int cmp_op = bol->in(1)->Opcode();
658 // It is expensive to generate flags from a float compare.
659 // Avoid duplicated float compare.
660 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
661
662 float infrequent_prob = PROB_UNLIKELY_MAG(3);
663 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
664 if (used_inside_loop) {
665 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
666
667 // BlockLayoutByFrequency optimization moves infrequent branch
668 // from hot path. No point in CMOV'ing in such case (110 is used
669 // instead of 100 to take into account not exactness of float value).
670 if (BlockLayoutByFrequency) {
671 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
672 }
673 }
674 // Check for highly predictable branch. No point in CMOV'ing if
675 // we are going to predict accurately all the time.
676 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
677 //keep going
678 } else if (iff->_prob < infrequent_prob ||
679 iff->_prob > (1.0f - infrequent_prob))
680 return NULL;
681
682 // --------------
683 // Now replace all Phis with CMOV's
684 Node *cmov_ctrl = iff->in(0);
685 uint flip = (lp->Opcode() == Op_IfTrue);
686 Node_List wq;
687 while (1) {
688 PhiNode* phi = NULL;
689 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
690 Node *out = region->fast_out(i);
691 if (out->is_Phi()) {
692 phi = out->as_Phi();
693 break;
694 }
695 }
696 if (phi == NULL) break;
697 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
698 // Move speculative ops
699 wq.push(phi);
700 while (wq.size() > 0) {
701 Node *n = wq.pop();
702 for (uint j = 1; j < n->req(); j++) {
703 Node* m = n->in(j);
704 if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
705 #ifndef PRODUCT
706 if (PrintOpto && VerifyLoopOptimizations) {
707 tty->print(" speculate: ");
708 m->dump();
709 }
710 #endif
711 set_ctrl(m, cmov_ctrl);
712 wq.push(m);
713 }
714 }
715 }
716 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
717 register_new_node( cmov, cmov_ctrl );
718 _igvn.replace_node( phi, cmov );
719 #ifndef PRODUCT
720 if (TraceLoopOpts) {
721 tty->print("CMOV ");
722 r_loop->dump_head();
723 if (Verbose) {
724 bol->in(1)->dump(1);
725 cmov->dump(1);
726 }
727 }
728 if (VerifyLoopOptimizations) verify();
729 #endif
730 }
731
732 // The useless CFG diamond will fold up later; see the optimization in
733 // RegionNode::Ideal.
734 _igvn._worklist.push(region);
735
736 return iff->in(1);
737 }
738
739 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
740 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
741 Node* u = m->fast_out(i);
742 if (u->is_CFG()) {
743 if (u->Opcode() == Op_NeverBranch) {
744 u = ((NeverBranchNode*)u)->proj_out(0);
745 enqueue_cfg_uses(u, wq);
746 } else {
747 wq.push(u);
748 }
749 }
750 }
751 }
752
753 // Try moving a store out of a loop, right before the loop
754 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
755 // Store has to be first in the loop body
756 IdealLoopTree *n_loop = get_loop(n_ctrl);
757 if (n->is_Store() && n_loop != _ltree_root &&
758 n_loop->is_loop() && n_loop->_head->is_Loop() &&
759 n->in(0) != NULL) {
760 Node* address = n->in(MemNode::Address);
761 Node* value = n->in(MemNode::ValueIn);
762 Node* mem = n->in(MemNode::Memory);
763 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
764 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
765
766 // - address and value must be loop invariant
767 // - memory must be a memory Phi for the loop
768 // - Store must be the only store on this memory slice in the
769 // loop: if there's another store following this one then value
770 // written at iteration i by the second store could be overwritten
771 // at iteration i+n by the first store: it's not safe to move the
772 // first store out of the loop
773 // - nothing must observe the memory Phi: it guarantees no read
774 // before the store, we are also guaranteed the store post
775 // dominates the loop head (ignoring a possible early
776 // exit). Otherwise there would be extra Phi involved between the
777 // loop's Phi and the store.
778 // - there must be no early exit from the loop before the Store
779 // (such an exit most of the time would be an extra use of the
780 // memory Phi but sometimes is a bottom memory Phi that takes the
781 // store as input).
782
783 if (!n_loop->is_member(address_loop) &&
784 !n_loop->is_member(value_loop) &&
785 mem->is_Phi() && mem->in(0) == n_loop->_head &&
786 mem->outcnt() == 1 &&
787 mem->in(LoopNode::LoopBackControl) == n) {
788
789 assert(n_loop->_tail != NULL, "need a tail");
790 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
791
792 // Verify that there's no early exit of the loop before the store.
793 bool ctrl_ok = false;
794 {
795 // Follow control from loop head until n, we exit the loop or
796 // we reach the tail
797 ResourceMark rm;
798 Unique_Node_List wq;
799 wq.push(n_loop->_head);
800
801 for (uint next = 0; next < wq.size(); ++next) {
802 Node *m = wq.at(next);
803 if (m == n->in(0)) {
804 ctrl_ok = true;
805 continue;
806 }
807 assert(!has_ctrl(m), "should be CFG");
808 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
809 ctrl_ok = false;
810 break;
811 }
812 enqueue_cfg_uses(m, wq);
813 if (wq.size() > 10) {
814 ctrl_ok = false;
815 break;
816 }
817 }
818 }
819 if (ctrl_ok) {
820 // move the Store
821 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
822 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
823 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
824 // Disconnect the phi now. An empty phi can confuse other
825 // optimizations in this pass of loop opts.
826 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
827 n_loop->_body.yank(mem);
828
829 set_ctrl_and_loop(n, n->in(0));
830
831 return n;
832 }
833 }
834 }
835 return NULL;
836 }
837
838 // Try moving a store out of a loop, right after the loop
839 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
840 if (n->is_Store() && n->in(0) != NULL) {
841 Node *n_ctrl = get_ctrl(n);
842 IdealLoopTree *n_loop = get_loop(n_ctrl);
843 // Store must be in a loop
844 if (n_loop != _ltree_root && !n_loop->_irreducible) {
845 Node* address = n->in(MemNode::Address);
846 Node* value = n->in(MemNode::ValueIn);
847 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
848 // address must be loop invariant
849 if (!n_loop->is_member(address_loop)) {
850 // Store must be last on this memory slice in the loop and
851 // nothing in the loop must observe it
852 Node* phi = NULL;
853 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
854 Node* u = n->fast_out(i);
855 if (has_ctrl(u)) { // control use?
856 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
857 if (!n_loop->is_member(u_loop)) {
858 continue;
859 }
860 if (u->is_Phi() && u->in(0) == n_loop->_head) {
861 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
862 // multiple phis on the same slice are possible
863 if (phi != NULL) {
864 return;
865 }
866 phi = u;
867 continue;
868 }
869 }
870 return;
871 }
872 if (phi != NULL) {
873 // Nothing in the loop before the store (next iteration)
874 // must observe the stored value
875 bool mem_ok = true;
876 {
877 ResourceMark rm;
878 Unique_Node_List wq;
879 wq.push(phi);
880 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
881 Node *m = wq.at(next);
882 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
883 Node* u = m->fast_out(i);
884 if (u->is_Store() || u->is_Phi()) {
885 if (u != n) {
886 wq.push(u);
887 mem_ok = (wq.size() <= 10);
888 }
889 } else {
890 mem_ok = false;
891 break;
892 }
893 }
894 }
895 }
896 if (mem_ok) {
897 // Move the store out of the loop if the LCA of all
898 // users (except for the phi) is outside the loop.
899 Node* hook = new Node(1);
900 _igvn.rehash_node_delayed(phi);
901 int count = phi->replace_edge(n, hook);
902 assert(count > 0, "inconsistent phi");
903
904 // Compute latest point this store can go
905 Node* lca = get_late_ctrl(n, get_ctrl(n));
906 if (n_loop->is_member(get_loop(lca))) {
907 // LCA is in the loop - bail out
908 _igvn.replace_node(hook, n);
909 return;
910 }
911 #ifdef ASSERT
912 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
913 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
914 n_loop->_head->as_Loop()->verify_strip_mined(1);
915 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
916 IdealLoopTree* outer_loop = get_loop(outer);
917 assert(n_loop->_parent == outer_loop, "broken loop tree");
918 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
919 }
920 #endif
921
922 // Move store out of the loop
923 _igvn.replace_node(hook, n->in(MemNode::Memory));
924 _igvn.replace_input_of(n, 0, lca);
925 set_ctrl_and_loop(n, lca);
926
927 // Disconnect the phi now. An empty phi can confuse other
928 // optimizations in this pass of loop opts..
929 if (phi->in(LoopNode::LoopBackControl) == phi) {
930 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
931 n_loop->_body.yank(phi);
932 }
933 }
934 }
935 }
936 }
937 }
938 }
939
940 //------------------------------split_if_with_blocks_pre-----------------------
941 // Do the real work in a non-recursive function. Data nodes want to be
942 // cloned in the pre-order so they can feed each other nicely.
943 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
944 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
945 Node* bs_res = bs->split_if_pre(this, n);
946 if (bs_res != NULL) {
947 return bs_res;
948 }
949 // Cloning these guys is unlikely to win
950 int n_op = n->Opcode();
951 if( n_op == Op_MergeMem ) return n;
952 if( n->is_Proj() ) return n;
953 // Do not clone-up CmpFXXX variations, as these are always
954 // followed by a CmpI
955 if( n->is_Cmp() ) return n;
956 // Attempt to use a conditional move instead of a phi/branch
957 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
958 Node *cmov = conditional_move( n );
959 if( cmov ) return cmov;
960 }
961 if( n->is_CFG() || n->is_LoadStore() )
962 return n;
963 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
964 n_op == Op_Opaque2 ) {
965 if( !C->major_progress() ) // If chance of no more loop opts...
966 _igvn._worklist.push(n); // maybe we'll remove them
967 return n;
968 }
969
970 if( n->is_Con() ) return n; // No cloning for Con nodes
971
972 Node *n_ctrl = get_ctrl(n);
973 if( !n_ctrl ) return n; // Dead node
974
975 Node* res = try_move_store_before_loop(n, n_ctrl);
976 if (res != NULL) {
977 return n;
978 }
979
980 // Attempt to remix address expressions for loop invariants
981 Node *m = remix_address_expressions( n );
982 if( m ) return m;
983
984 if (n_op == Op_AddI) {
985 Node *nn = convert_add_to_muladd( n );
986 if ( nn ) return nn;
987 }
988
989 if (n->is_ConstraintCast()) {
990 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
991 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
992 // Node control inputs don't necessarily agree with loop control info (due to
993 // transformations happened in between), thus additional dominance check is needed
994 // to keep loop info valid.
995 if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
996 _igvn.replace_node(n, dom_cast);
997 return dom_cast;
998 }
999 }
1000
1001 // Determine if the Node has inputs from some local Phi.
1002 // Returns the block to clone thru.
1003 Node *n_blk = has_local_phi_input( n );
1004 if( !n_blk ) return n;
1005
1006 // Do not clone the trip counter through on a CountedLoop
1007 // (messes up the canonical shape).
1008 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
1009
1010 // Check for having no control input; not pinned. Allow
1011 // dominating control.
1012 if (n->in(0)) {
1013 Node *dom = idom(n_blk);
1014 if (dom_lca(n->in(0), dom) != n->in(0)) {
1015 return n;
1016 }
1017 }
1018 // Policy: when is it profitable. You must get more wins than
1019 // policy before it is considered profitable. Policy is usually 0,
1020 // so 1 win is considered profitable. Big merges will require big
1021 // cloning, so get a larger policy.
1022 int policy = n_blk->req() >> 2;
1023
1024 // If the loop is a candidate for range check elimination,
1025 // delay splitting through it's phi until a later loop optimization
1026 if (n_blk->is_CountedLoop()) {
1027 IdealLoopTree *lp = get_loop(n_blk);
1028 if (lp && lp->_rce_candidate) {
1029 return n;
1030 }
1031 }
1032
1033 if (must_throttle_split_if()) return n;
1034
1035 // Split 'n' through the merge point if it is profitable
1036 Node *phi = split_thru_phi( n, n_blk, policy );
1037 if (!phi) return n;
1038
1039 // Found a Phi to split thru!
1040 // Replace 'n' with the new phi
1041 _igvn.replace_node( n, phi );
1042 // Moved a load around the loop, 'en-registering' something.
1043 if (n_blk->is_Loop() && n->is_Load() &&
1044 !phi->in(LoopNode::LoopBackControl)->is_Load())
1045 C->set_major_progress();
1046
1047 return phi;
1048 }
1049
1050 static bool merge_point_too_heavy(Compile* C, Node* region) {
1051 // Bail out if the region and its phis have too many users.
1052 int weight = 0;
1053 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1054 weight += region->fast_out(i)->outcnt();
1055 }
1056 int nodes_left = C->max_node_limit() - C->live_nodes();
1057 if (weight * 8 > nodes_left) {
1058 if (PrintOpto) {
1059 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
1060 }
1061 return true;
1062 } else {
1063 return false;
1064 }
1065 }
1066
1067 static bool merge_point_safe(Node* region) {
1068 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1069 // having a PhiNode input. This sidesteps the dangerous case where the split
1070 // ConvI2LNode may become TOP if the input Value() does not
1071 // overlap the ConvI2L range, leaving a node which may not dominate its
1072 // uses.
1073 // A better fix for this problem can be found in the BugTraq entry, but
1074 // expediency for Mantis demands this hack.
1075 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1076 // split_if_with_blocks from splitting a block because we could not move around
1077 // the FastLockNode.
1078 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1079 Node* n = region->fast_out(i);
1080 if (n->is_Phi()) {
1081 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1082 Node* m = n->fast_out(j);
1083 if (m->is_FastLock())
1084 return false;
1085 #ifdef _LP64
1086 if (m->Opcode() == Op_ConvI2L)
1087 return false;
1088 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1089 return false;
1090 }
1091 #endif
1092 }
1093 }
1094 }
1095 return true;
1096 }
1097
1098
1099 //------------------------------place_near_use---------------------------------
1100 // Place some computation next to use but not inside inner loops.
1101 // For inner loop uses move it to the preheader area.
1102 Node *PhaseIdealLoop::place_near_use(Node *useblock) const {
1103 IdealLoopTree *u_loop = get_loop( useblock );
1104 if (u_loop->_irreducible) {
1105 return useblock;
1106 }
1107 if (u_loop->_child) {
1108 if (useblock == u_loop->_head && u_loop->_head->is_OuterStripMinedLoop()) {
1109 return u_loop->_head->in(LoopNode::EntryControl);
1110 }
1111 return useblock;
1112 }
1113 return u_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1114 }
1115
1116
1117 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1118 if (!n->is_If() || n->is_CountedLoopEnd()) {
1119 return false;
1120 }
1121 if (!n->in(0)->is_Region()) {
1122 return false;
1123 }
1124 Node* region = n->in(0);
1125 Node* dom = idom(region);
1126 if (!dom->is_If() || dom->in(1) != n->in(1)) {
1127 return false;
1128 }
1129 IfNode* dom_if = dom->as_If();
1130 Node* proj_true = dom_if->proj_out(1);
1131 Node* proj_false = dom_if->proj_out(0);
1132
1133 for (uint i = 1; i < region->req(); i++) {
1134 if (is_dominator(proj_true, region->in(i))) {
1135 continue;
1136 }
1137 if (is_dominator(proj_false, region->in(i))) {
1138 continue;
1139 }
1140 return false;
1141 }
1142
1143 return true;
1144 }
1145
1146
1147 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1148 if (must_throttle_split_if()) {
1149 return false;
1150 }
1151
1152 // Do not do 'split-if' if irreducible loops are present.
1153 if (_has_irreducible_loops) {
1154 return false;
1155 }
1156
1157 if (merge_point_too_heavy(C, n_ctrl)) {
1158 return false;
1159 }
1160
1161 // Do not do 'split-if' if some paths are dead. First do dead code
1162 // elimination and then see if its still profitable.
1163 for (uint i = 1; i < n_ctrl->req(); i++) {
1164 if (n_ctrl->in(i) == C->top()) {
1165 return false;
1166 }
1167 }
1168
1169 // If trying to do a 'Split-If' at the loop head, it is only
1170 // profitable if the cmp folds up on BOTH paths. Otherwise we
1171 // risk peeling a loop forever.
1172
1173 // CNC - Disabled for now. Requires careful handling of loop
1174 // body selection for the cloned code. Also, make sure we check
1175 // for any input path not being in the same loop as n_ctrl. For
1176 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1177 // because the alternative loop entry points won't be converted
1178 // into LoopNodes.
1179 IdealLoopTree *n_loop = get_loop(n_ctrl);
1180 for (uint j = 1; j < n_ctrl->req(); j++) {
1181 if (get_loop(n_ctrl->in(j)) != n_loop) {
1182 return false;
1183 }
1184 }
1185
1186 // Check for safety of the merge point.
1187 if (!merge_point_safe(n_ctrl)) {
1188 return false;
1189 }
1190
1191 return true;
1192 }
1193
1194 // Detect if the node is the inner strip-mined loop
1195 // Return: NULL if it's not the case, or the exit of outer strip-mined loop
1196 static Node* is_inner_of_stripmined_loop(const Node* out) {
1197 Node* out_le = NULL;
1198
1199 if (out->is_CountedLoopEnd()) {
1200 const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1201
1202 if (loop != NULL && loop->is_strip_mined()) {
1203 out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1204 }
1205 }
1206
1207 return out_le;
1208 }
1209
1210 //------------------------------split_if_with_blocks_post----------------------
1211 // Do the real work in a non-recursive function. CFG hackery wants to be
1212 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1213 // info.
1214 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1215
1216 // Cloning Cmp through Phi's involves the split-if transform.
1217 // FastLock is not used by an If
1218 if (n->is_Cmp() && !n->is_FastLock()) {
1219 Node *n_ctrl = get_ctrl(n);
1220 // Determine if the Node has inputs from some local Phi.
1221 // Returns the block to clone thru.
1222 Node *n_blk = has_local_phi_input(n);
1223 if (n_blk != n_ctrl) {
1224 return;
1225 }
1226
1227 if (!can_split_if(n_ctrl)) {
1228 return;
1229 }
1230
1231 if (n->outcnt() != 1) {
1232 return; // Multiple bool's from 1 compare?
1233 }
1234 Node *bol = n->unique_out();
1235 assert(bol->is_Bool(), "expect a bool here");
1236 if (bol->outcnt() != 1) {
1237 return;// Multiple branches from 1 compare?
1238 }
1239 Node *iff = bol->unique_out();
1240
1241 // Check some safety conditions
1242 if (iff->is_If()) { // Classic split-if?
1243 if (iff->in(0) != n_ctrl) {
1244 return; // Compare must be in same blk as if
1245 }
1246 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1247 // Can't split CMove with different control edge.
1248 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1249 return;
1250 }
1251 if (get_ctrl(iff->in(2)) == n_ctrl ||
1252 get_ctrl(iff->in(3)) == n_ctrl) {
1253 return; // Inputs not yet split-up
1254 }
1255 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1256 return; // Loop-invar test gates loop-varying CMOVE
1257 }
1258 } else {
1259 return; // some other kind of node, such as an Allocate
1260 }
1261
1262 // When is split-if profitable? Every 'win' on means some control flow
1263 // goes dead, so it's almost always a win.
1264 int policy = 0;
1265 // Split compare 'n' through the merge point if it is profitable
1266 Node *phi = split_thru_phi( n, n_ctrl, policy);
1267 if (!phi) {
1268 return;
1269 }
1270
1271 // Found a Phi to split thru!
1272 // Replace 'n' with the new phi
1273 _igvn.replace_node(n, phi);
1274
1275 // Now split the bool up thru the phi
1276 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1277 guarantee(bolphi != NULL, "null boolean phi node");
1278
1279 _igvn.replace_node(bol, bolphi);
1280 assert(iff->in(1) == bolphi, "");
1281
1282 if (bolphi->Value(&_igvn)->singleton()) {
1283 return;
1284 }
1285
1286 // Conditional-move? Must split up now
1287 if (!iff->is_If()) {
1288 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1289 _igvn.replace_node(iff, cmovphi);
1290 return;
1291 }
1292
1293 // Now split the IF
1294 do_split_if(iff);
1295 return;
1296 }
1297
1298 // Two identical ifs back to back can be merged
1299 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1300 Node *n_ctrl = n->in(0);
1301 PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1302 IfNode* dom_if = idom(n_ctrl)->as_If();
1303 Node* proj_true = dom_if->proj_out(1);
1304 Node* proj_false = dom_if->proj_out(0);
1305 Node* con_true = _igvn.makecon(TypeInt::ONE);
1306 Node* con_false = _igvn.makecon(TypeInt::ZERO);
1307
1308 for (uint i = 1; i < n_ctrl->req(); i++) {
1309 if (is_dominator(proj_true, n_ctrl->in(i))) {
1310 bolphi->init_req(i, con_true);
1311 } else {
1312 assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1313 bolphi->init_req(i, con_false);
1314 }
1315 }
1316 register_new_node(bolphi, n_ctrl);
1317 _igvn.replace_input_of(n, 1, bolphi);
1318
1319 // Now split the IF
1320 do_split_if(n);
1321 return;
1322 }
1323
1324 // Check for an IF ready to split; one that has its
1325 // condition codes input coming from a Phi at the block start.
1326 int n_op = n->Opcode();
1327
1328 // Check for an IF being dominated by another IF same test
1329 if (n_op == Op_If ||
1330 n_op == Op_RangeCheck) {
1331 Node *bol = n->in(1);
1332 uint max = bol->outcnt();
1333 // Check for same test used more than once?
1334 if (max > 1 && bol->is_Bool()) {
1335 // Search up IDOMs to see if this IF is dominated.
1336 Node *cutoff = get_ctrl(bol);
1337
1338 // Now search up IDOMs till cutoff, looking for a dominating test
1339 Node *prevdom = n;
1340 Node *dom = idom(prevdom);
1341 while (dom != cutoff) {
1342 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1343 // It's invalid to move control dependent data nodes in the inner
1344 // strip-mined loop, because:
1345 // 1) break validation of LoopNode::verify_strip_mined()
1346 // 2) move code with side-effect in strip-mined loop
1347 // Move to the exit of outer strip-mined loop in that case.
1348 Node* out_le = is_inner_of_stripmined_loop(dom);
1349 if (out_le != NULL) {
1350 prevdom = out_le;
1351 }
1352 // Replace the dominated test with an obvious true or false.
1353 // Place it on the IGVN worklist for later cleanup.
1354 C->set_major_progress();
1355 dominated_by(prevdom, n, false, true);
1356 #ifndef PRODUCT
1357 if( VerifyLoopOptimizations ) verify();
1358 #endif
1359 return;
1360 }
1361 prevdom = dom;
1362 dom = idom(prevdom);
1363 }
1364 }
1365 }
1366
1367 // See if a shared loop-varying computation has no loop-varying uses.
1368 // Happens if something is only used for JVM state in uncommon trap exits,
1369 // like various versions of induction variable+offset. Clone the
1370 // computation per usage to allow it to sink out of the loop.
1371 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1372 Node *n_ctrl = get_ctrl(n);
1373 IdealLoopTree *n_loop = get_loop(n_ctrl);
1374 if( n_loop != _ltree_root ) {
1375 DUIterator_Fast imax, i = n->fast_outs(imax);
1376 for (; i < imax; i++) {
1377 Node* u = n->fast_out(i);
1378 if( !has_ctrl(u) ) break; // Found control user
1379 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1380 if( u_loop == n_loop ) break; // Found loop-varying use
1381 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1382 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1383 }
1384 bool did_break = (i < imax); // Did we break out of the previous loop?
1385 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1386 Node *late_load_ctrl = NULL;
1387 if (n->is_Load()) {
1388 // If n is a load, get and save the result from get_late_ctrl(),
1389 // to be later used in calculating the control for n's clones.
1390 clear_dom_lca_tags();
1391 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1392 }
1393 // If n is a load, and the late control is the same as the current
1394 // control, then the cloning of n is a pointless exercise, because
1395 // GVN will ensure that we end up where we started.
1396 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1397 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1398 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1399 Node *u = n->last_out(j); // Clone private computation per use
1400 _igvn.rehash_node_delayed(u);
1401 Node *x = n->clone(); // Clone computation
1402 Node *x_ctrl = NULL;
1403 if( u->is_Phi() ) {
1404 // Replace all uses of normal nodes. Replace Phi uses
1405 // individually, so the separate Nodes can sink down
1406 // different paths.
1407 uint k = 1;
1408 while( u->in(k) != n ) k++;
1409 u->set_req( k, x );
1410 // x goes next to Phi input path
1411 x_ctrl = u->in(0)->in(k);
1412 --j;
1413 } else { // Normal use
1414 // Replace all uses
1415 for( uint k = 0; k < u->req(); k++ ) {
1416 if( u->in(k) == n ) {
1417 u->set_req( k, x );
1418 --j;
1419 }
1420 }
1421 x_ctrl = get_ctrl(u);
1422 }
1423
1424 // Find control for 'x' next to use but not inside inner loops.
1425 // For inner loop uses get the preheader area.
1426 x_ctrl = place_near_use(x_ctrl);
1427
1428 if (bs->sink_node(this, n, x, x_ctrl, n_ctrl)) {
1429 continue;
1430 }
1431
1432 if (n->is_Load()) {
1433 // For loads, add a control edge to a CFG node outside of the loop
1434 // to force them to not combine and return back inside the loop
1435 // during GVN optimization (4641526).
1436 //
1437 // Because we are setting the actual control input, factor in
1438 // the result from get_late_ctrl() so we respect any
1439 // anti-dependences. (6233005).
1440 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1441
1442 // Don't allow the control input to be a CFG splitting node.
1443 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1444 // should only have IfTrueNode and IfFalseNode (4985384).
1445 x_ctrl = find_non_split_ctrl(x_ctrl);
1446
1447 IdealLoopTree* x_loop = get_loop(x_ctrl);
1448 Node* x_head = x_loop->_head;
1449 if (x_head->is_Loop() && (x_head->is_OuterStripMinedLoop() || x_head->as_Loop()->is_strip_mined()) && is_dominator(n_ctrl, x_head)) {
1450 // Anti dependence analysis is sometimes too
1451 // conservative: a store in the outer strip mined loop
1452 // can prevent a load from floating out of the outer
1453 // strip mined loop but the load may not be referenced
1454 // from the safepoint: loop strip mining verification
1455 // code reports a problem in that case. Make sure the
1456 // load is not moved in the outer strip mined loop in
1457 // that case.
1458 x_ctrl = x_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1459 }
1460 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1461
1462 x->set_req(0, x_ctrl);
1463 }
1464 register_new_node(x, x_ctrl);
1465
1466 // Some institutional knowledge is needed here: 'x' is
1467 // yanked because if the optimizer runs GVN on it all the
1468 // cloned x's will common up and undo this optimization and
1469 // be forced back in the loop.
1470 // I tried setting control edges on the x's to force them to
1471 // not combine, but the matching gets worried when it tries
1472 // to fold a StoreP and an AddP together (as part of an
1473 // address expression) and the AddP and StoreP have
1474 // different controls.
1475 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1476 }
1477 _igvn.remove_dead_node(n);
1478 }
1479 }
1480 }
1481 }
1482
1483 try_move_store_after_loop(n);
1484
1485 // Check for Opaque2's who's loop has disappeared - who's input is in the
1486 // same loop nest as their output. Remove 'em, they are no longer useful.
1487 if( n_op == Op_Opaque2 &&
1488 n->in(1) != NULL &&
1489 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1490 _igvn.replace_node( n, n->in(1) );
1491 }
1492 }
1493
1494 //------------------------------split_if_with_blocks---------------------------
1495 // Check for aggressive application of 'split-if' optimization,
1496 // using basic block level info.
1497 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1498 Node* root = C->root();
1499 visited.set(root->_idx); // first, mark root as visited
1500 // Do pre-visit work for root
1501 Node* n = split_if_with_blocks_pre(root);
1502 uint cnt = n->outcnt();
1503 uint i = 0;
1504
1505 while (true) {
1506 // Visit all children
1507 if (i < cnt) {
1508 Node* use = n->raw_out(i);
1509 ++i;
1510 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1511 // Now do pre-visit work for this use
1512 use = split_if_with_blocks_pre(use);
1513 nstack.push(n, i); // Save parent and next use's index.
1514 n = use; // Process all children of current use.
1515 cnt = use->outcnt();
1516 i = 0;
1517 }
1518 }
1519 else {
1520 // All of n's children have been processed, complete post-processing.
1521 if (cnt != 0 && !n->is_Con()) {
1522 assert(has_node(n), "no dead nodes");
1523 split_if_with_blocks_post(n);
1524 }
1525 if (must_throttle_split_if()) {
1526 nstack.clear();
1527 }
1528 if (nstack.is_empty()) {
1529 // Finished all nodes on stack.
1530 break;
1531 }
1532 // Get saved parent node and next use's index. Visit the rest of uses.
1533 n = nstack.node();
1534 cnt = n->outcnt();
1535 i = nstack.index();
1536 nstack.pop();
1537 }
1538 }
1539 }
1540
1541
1542 //=============================================================================
1543 //
1544 // C L O N E A L O O P B O D Y
1545 //
1546
1547 //------------------------------clone_iff--------------------------------------
1548 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1549 // "Nearly" because all Nodes have been cloned from the original in the loop,
1550 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1551 // through the Phi recursively, and return a Bool.
1552 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1553
1554 // Convert this Phi into a Phi merging Bools
1555 uint i;
1556 for (i = 1; i < phi->req(); i++) {
1557 Node *b = phi->in(i);
1558 if (b->is_Phi()) {
1559 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1560 } else {
1561 assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1562 }
1563 }
1564
1565 Node* n = phi->in(1);
1566 Node* sample_opaque = NULL;
1567 Node *sample_bool = NULL;
1568 if (n->Opcode() == Op_Opaque4) {
1569 sample_opaque = n;
1570 sample_bool = n->in(1);
1571 assert(sample_bool->is_Bool(), "wrong type");
1572 } else {
1573 sample_bool = n;
1574 }
1575 Node *sample_cmp = sample_bool->in(1);
1576
1577 // Make Phis to merge the Cmp's inputs.
1578 PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1579 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1580 for (i = 1; i < phi->req(); i++) {
1581 Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1582 Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1583 phi1->set_req(i, n1);
1584 phi2->set_req(i, n2);
1585 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1586 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1587 }
1588 // See if these Phis have been made before.
1589 // Register with optimizer
1590 Node *hit1 = _igvn.hash_find_insert(phi1);
1591 if (hit1) { // Hit, toss just made Phi
1592 _igvn.remove_dead_node(phi1); // Remove new phi
1593 assert(hit1->is_Phi(), "" );
1594 phi1 = (PhiNode*)hit1; // Use existing phi
1595 } else { // Miss
1596 _igvn.register_new_node_with_optimizer(phi1);
1597 }
1598 Node *hit2 = _igvn.hash_find_insert(phi2);
1599 if (hit2) { // Hit, toss just made Phi
1600 _igvn.remove_dead_node(phi2); // Remove new phi
1601 assert(hit2->is_Phi(), "" );
1602 phi2 = (PhiNode*)hit2; // Use existing phi
1603 } else { // Miss
1604 _igvn.register_new_node_with_optimizer(phi2);
1605 }
1606 // Register Phis with loop/block info
1607 set_ctrl(phi1, phi->in(0));
1608 set_ctrl(phi2, phi->in(0));
1609 // Make a new Cmp
1610 Node *cmp = sample_cmp->clone();
1611 cmp->set_req(1, phi1);
1612 cmp->set_req(2, phi2);
1613 _igvn.register_new_node_with_optimizer(cmp);
1614 set_ctrl(cmp, phi->in(0));
1615
1616 // Make a new Bool
1617 Node *b = sample_bool->clone();
1618 b->set_req(1,cmp);
1619 _igvn.register_new_node_with_optimizer(b);
1620 set_ctrl(b, phi->in(0));
1621
1622 if (sample_opaque != NULL) {
1623 Node* opaque = sample_opaque->clone();
1624 opaque->set_req(1, b);
1625 _igvn.register_new_node_with_optimizer(opaque);
1626 set_ctrl(opaque, phi->in(0));
1627 return opaque;
1628 }
1629
1630 assert(b->is_Bool(), "");
1631 return b;
1632 }
1633
1634 //------------------------------clone_bool-------------------------------------
1635 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1636 // "Nearly" because all Nodes have been cloned from the original in the loop,
1637 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1638 // through the Phi recursively, and return a Bool.
1639 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1640 uint i;
1641 // Convert this Phi into a Phi merging Bools
1642 for( i = 1; i < phi->req(); i++ ) {
1643 Node *b = phi->in(i);
1644 if( b->is_Phi() ) {
1645 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1646 } else {
1647 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1648 }
1649 }
1650
1651 Node *sample_cmp = phi->in(1);
1652
1653 // Make Phis to merge the Cmp's inputs.
1654 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1655 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1656 for( uint j = 1; j < phi->req(); j++ ) {
1657 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1658 Node *n1, *n2;
1659 if( cmp_top->is_Cmp() ) {
1660 n1 = cmp_top->in(1);
1661 n2 = cmp_top->in(2);
1662 } else {
1663 n1 = n2 = cmp_top;
1664 }
1665 phi1->set_req( j, n1 );
1666 phi2->set_req( j, n2 );
1667 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1668 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1669 }
1670
1671 // See if these Phis have been made before.
1672 // Register with optimizer
1673 Node *hit1 = _igvn.hash_find_insert(phi1);
1674 if( hit1 ) { // Hit, toss just made Phi
1675 _igvn.remove_dead_node(phi1); // Remove new phi
1676 assert( hit1->is_Phi(), "" );
1677 phi1 = (PhiNode*)hit1; // Use existing phi
1678 } else { // Miss
1679 _igvn.register_new_node_with_optimizer(phi1);
1680 }
1681 Node *hit2 = _igvn.hash_find_insert(phi2);
1682 if( hit2 ) { // Hit, toss just made Phi
1683 _igvn.remove_dead_node(phi2); // Remove new phi
1684 assert( hit2->is_Phi(), "" );
1685 phi2 = (PhiNode*)hit2; // Use existing phi
1686 } else { // Miss
1687 _igvn.register_new_node_with_optimizer(phi2);
1688 }
1689 // Register Phis with loop/block info
1690 set_ctrl(phi1, phi->in(0));
1691 set_ctrl(phi2, phi->in(0));
1692 // Make a new Cmp
1693 Node *cmp = sample_cmp->clone();
1694 cmp->set_req( 1, phi1 );
1695 cmp->set_req( 2, phi2 );
1696 _igvn.register_new_node_with_optimizer(cmp);
1697 set_ctrl(cmp, phi->in(0));
1698
1699 assert( cmp->is_Cmp(), "" );
1700 return (CmpNode*)cmp;
1701 }
1702
1703 //------------------------------sink_use---------------------------------------
1704 // If 'use' was in the loop-exit block, it now needs to be sunk
1705 // below the post-loop merge point.
1706 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1707 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1708 set_ctrl(use, post_loop);
1709 for (DUIterator j = use->outs(); use->has_out(j); j++)
1710 sink_use(use->out(j), post_loop);
1711 }
1712 }
1713
1714 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1715 IdealLoopTree* loop, IdealLoopTree* outer_loop,
1716 Node_List*& split_if_set, Node_List*& split_bool_set,
1717 Node_List*& split_cex_set, Node_List& worklist,
1718 uint new_counter, CloneLoopMode mode) {
1719 Node* nnn = old_new[old->_idx];
1720 // Copy uses to a worklist, so I can munge the def-use info
1721 // with impunity.
1722 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1723 worklist.push(old->fast_out(j));
1724
1725 while( worklist.size() ) {
1726 Node *use = worklist.pop();
1727 if (!has_node(use)) continue; // Ignore dead nodes
1728 if (use->in(0) == C->top()) continue;
1729 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1730 // Check for data-use outside of loop - at least one of OLD or USE
1731 // must not be a CFG node.
1732 #ifdef ASSERT
1733 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1734 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1735 assert(mode == ControlAroundStripMined && (use == sfpt || !use->is_reachable_from_root()), "missed a node");
1736 }
1737 #endif
1738 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1739
1740 // If the Data use is an IF, that means we have an IF outside of the
1741 // loop that is switching on a condition that is set inside of the
1742 // loop. Happens if people set a loop-exit flag; then test the flag
1743 // in the loop to break the loop, then test is again outside of the
1744 // loop to determine which way the loop exited.
1745 // Loop predicate If node connects to Bool node through Opaque1 node.
1746 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1747 // Since this code is highly unlikely, we lazily build the worklist
1748 // of such Nodes to go split.
1749 if (!split_if_set) {
1750 ResourceArea *area = Thread::current()->resource_area();
1751 split_if_set = new Node_List(area);
1752 }
1753 split_if_set->push(use);
1754 }
1755 if (use->is_Bool()) {
1756 if (!split_bool_set) {
1757 ResourceArea *area = Thread::current()->resource_area();
1758 split_bool_set = new Node_List(area);
1759 }
1760 split_bool_set->push(use);
1761 }
1762 if (use->Opcode() == Op_CreateEx) {
1763 if (!split_cex_set) {
1764 ResourceArea *area = Thread::current()->resource_area();
1765 split_cex_set = new Node_List(area);
1766 }
1767 split_cex_set->push(use);
1768 }
1769
1770
1771 // Get "block" use is in
1772 uint idx = 0;
1773 while( use->in(idx) != old ) idx++;
1774 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1775 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1776 Node *cfg = prev->_idx >= new_counter
1777 ? prev->in(2)
1778 : idom(prev);
1779 if( use->is_Phi() ) // Phi use is in prior block
1780 cfg = prev->in(idx); // NOT in block of Phi itself
1781 if (cfg->is_top()) { // Use is dead?
1782 _igvn.replace_input_of(use, idx, C->top());
1783 continue;
1784 }
1785
1786 // If use is referenced through control edge... (idx == 0)
1787 if (mode == IgnoreStripMined && idx == 0) {
1788 LoopNode *head = loop->_head->as_Loop();
1789 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1790 // That node is outside the inner loop, leave it outside the
1791 // outer loop as well to not confuse verification code.
1792 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1793 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1794 continue;
1795 }
1796 }
1797
1798 while(!outer_loop->is_member(get_loop(cfg))) {
1799 prev = cfg;
1800 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1801 }
1802 // If the use occurs after merging several exits from the loop, then
1803 // old value must have dominated all those exits. Since the same old
1804 // value was used on all those exits we did not need a Phi at this
1805 // merge point. NOW we do need a Phi here. Each loop exit value
1806 // is now merged with the peeled body exit; each exit gets its own
1807 // private Phi and those Phis need to be merged here.
1808 Node *phi;
1809 if( prev->is_Region() ) {
1810 if( idx == 0 ) { // Updating control edge?
1811 phi = prev; // Just use existing control
1812 } else { // Else need a new Phi
1813 phi = PhiNode::make( prev, old );
1814 // Now recursively fix up the new uses of old!
1815 for( uint i = 1; i < prev->req(); i++ ) {
1816 worklist.push(phi); // Onto worklist once for each 'old' input
1817 }
1818 }
1819 } else {
1820 // Get new RegionNode merging old and new loop exits
1821 prev = old_new[prev->_idx];
1822 assert( prev, "just made this in step 7" );
1823 if( idx == 0) { // Updating control edge?
1824 phi = prev; // Just use existing control
1825 } else { // Else need a new Phi
1826 // Make a new Phi merging data values properly
1827 phi = PhiNode::make( prev, old );
1828 phi->set_req( 1, nnn );
1829 }
1830 }
1831 // If inserting a new Phi, check for prior hits
1832 if( idx != 0 ) {
1833 Node *hit = _igvn.hash_find_insert(phi);
1834 if( hit == NULL ) {
1835 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1836 } else { // or
1837 // Remove the new phi from the graph and use the hit
1838 _igvn.remove_dead_node(phi);
1839 phi = hit; // Use existing phi
1840 }
1841 set_ctrl(phi, prev);
1842 }
1843 // Make 'use' use the Phi instead of the old loop body exit value
1844 _igvn.replace_input_of(use, idx, phi);
1845 if( use->_idx >= new_counter ) { // If updating new phis
1846 // Not needed for correctness, but prevents a weak assert
1847 // in AddPNode from tripping (when we end up with different
1848 // base & derived Phis that will become the same after
1849 // IGVN does CSE).
1850 Node *hit = _igvn.hash_find_insert(use);
1851 if( hit ) // Go ahead and re-hash for hits.
1852 _igvn.replace_node( use, hit );
1853 }
1854
1855 // If 'use' was in the loop-exit block, it now needs to be sunk
1856 // below the post-loop merge point.
1857 sink_use( use, prev );
1858 }
1859 }
1860 }
1861
1862 static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
1863 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
1864 bool check_old_new) {
1865 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1866 Node* u = n->fast_out(j);
1867 assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
1868 if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
1869 Node* c = phase->get_ctrl(u);
1870 IdealLoopTree* u_loop = phase->get_loop(c);
1871 assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
1872 if (outer_loop->is_member(u_loop)) {
1873 wq.push(u);
1874 }
1875 }
1876 }
1877 }
1878
1879 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1880 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1881 Node_List& extra_data_nodes) {
1882 if (head->is_strip_mined() && mode != IgnoreStripMined) {
1883 CountedLoopNode* cl = head->as_CountedLoop();
1884 Node* l = cl->outer_loop();
1885 Node* tail = cl->outer_loop_tail();
1886 IfNode* le = cl->outer_loop_end();
1887 Node* sfpt = cl->outer_safepoint();
1888 CountedLoopEndNode* cle = cl->loopexit();
1889 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1890 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1891 Node* cle_out = cle->proj_out(false);
1892
1893 Node* new_sfpt = NULL;
1894 Node* new_cle_out = cle_out->clone();
1895 old_new.map(cle_out->_idx, new_cle_out);
1896 if (mode == CloneIncludesStripMined) {
1897 // clone outer loop body
1898 Node* new_l = l->clone();
1899 Node* new_tail = tail->clone();
1900 IfNode* new_le = le->clone()->as_If();
1901 new_sfpt = sfpt->clone();
1902
1903 set_loop(new_l, outer_loop->_parent);
1904 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1905 set_loop(new_cle_out, outer_loop->_parent);
1906 set_idom(new_cle_out, new_cle, dd);
1907 set_loop(new_sfpt, outer_loop->_parent);
1908 set_idom(new_sfpt, new_cle_out, dd);
1909 set_loop(new_le, outer_loop->_parent);
1910 set_idom(new_le, new_sfpt, dd);
1911 set_loop(new_tail, outer_loop->_parent);
1912 set_idom(new_tail, new_le, dd);
1913 set_idom(new_cl, new_l, dd);
1914
1915 old_new.map(l->_idx, new_l);
1916 old_new.map(tail->_idx, new_tail);
1917 old_new.map(le->_idx, new_le);
1918 old_new.map(sfpt->_idx, new_sfpt);
1919
1920 new_l->set_req(LoopNode::LoopBackControl, new_tail);
1921 new_l->set_req(0, new_l);
1922 new_tail->set_req(0, new_le);
1923 new_le->set_req(0, new_sfpt);
1924 new_sfpt->set_req(0, new_cle_out);
1925 new_cle_out->set_req(0, new_cle);
1926 new_cl->set_req(LoopNode::EntryControl, new_l);
1927
1928 _igvn.register_new_node_with_optimizer(new_l);
1929 _igvn.register_new_node_with_optimizer(new_tail);
1930 _igvn.register_new_node_with_optimizer(new_le);
1931 } else {
1932 Node *newhead = old_new[loop->_head->_idx];
1933 newhead->as_Loop()->clear_strip_mined();
1934 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
1935 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1936 }
1937 // Look at data node that were assigned a control in the outer
1938 // loop: they are kept in the outer loop by the safepoint so start
1939 // from the safepoint node's inputs.
1940 IdealLoopTree* outer_loop = get_loop(l);
1941 Node_Stack stack(2);
1942 stack.push(sfpt, 1);
1943 uint new_counter = C->unique();
1944 while (stack.size() > 0) {
1945 Node* n = stack.node();
1946 uint i = stack.index();
1947 while (i < n->req() &&
1948 (n->in(i) == NULL ||
1949 !has_ctrl(n->in(i)) ||
1950 get_loop(get_ctrl(n->in(i))) != outer_loop ||
1951 (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
1952 i++;
1953 }
1954 if (i < n->req()) {
1955 stack.set_index(i+1);
1956 stack.push(n->in(i), 0);
1957 } else {
1958 assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
1959 Node* m = n == sfpt ? new_sfpt : n->clone();
1960 if (m != NULL) {
1961 for (uint i = 0; i < n->req(); i++) {
1962 if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
1963 m->set_req(i, old_new[m->in(i)->_idx]);
1964 }
1965 }
1966 } else {
1967 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
1968 }
1969 if (n != sfpt) {
1970 extra_data_nodes.push(n);
1971 _igvn.register_new_node_with_optimizer(m);
1972 assert(get_ctrl(n) == cle_out, "what other control?");
1973 set_ctrl(m, new_cle_out);
1974 old_new.map(n->_idx, m);
1975 }
1976 stack.pop();
1977 }
1978 }
1979 if (mode == CloneIncludesStripMined) {
1980 _igvn.register_new_node_with_optimizer(new_sfpt);
1981 _igvn.register_new_node_with_optimizer(new_cle_out);
1982 }
1983 // Some other transformation may have pessimistically assign some
1984 // data nodes to the outer loop. Set their control so they are out
1985 // of the outer loop.
1986 ResourceMark rm;
1987 Unique_Node_List wq;
1988 for (uint i = 0; i < extra_data_nodes.size(); i++) {
1989 Node* old = extra_data_nodes.at(i);
1990 clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
1991 }
1992 Node* new_ctrl = cl->outer_loop_exit();
1993 assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
1994 for (uint i = 0; i < wq.size(); i++) {
1995 Node* n = wq.at(i);
1996 set_ctrl(n, new_ctrl);
1997 clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
1998 }
1999 } else {
2000 Node *newhead = old_new[loop->_head->_idx];
2001 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2002 }
2003 }
2004
2005 //------------------------------clone_loop-------------------------------------
2006 //
2007 // C L O N E A L O O P B O D Y
2008 //
2009 // This is the basic building block of the loop optimizations. It clones an
2010 // entire loop body. It makes an old_new loop body mapping; with this mapping
2011 // you can find the new-loop equivalent to an old-loop node. All new-loop
2012 // nodes are exactly equal to their old-loop counterparts, all edges are the
2013 // same. All exits from the old-loop now have a RegionNode that merges the
2014 // equivalent new-loop path. This is true even for the normal "loop-exit"
2015 // condition. All uses of loop-invariant old-loop values now come from (one
2016 // or more) Phis that merge their new-loop equivalents.
2017 //
2018 // This operation leaves the graph in an illegal state: there are two valid
2019 // control edges coming from the loop pre-header to both loop bodies. I'll
2020 // definitely have to hack the graph after running this transform.
2021 //
2022 // From this building block I will further edit edges to perform loop peeling
2023 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2024 //
2025 // Parameter side_by_size_idom:
2026 // When side_by_size_idom is NULL, the dominator tree is constructed for
2027 // the clone loop to dominate the original. Used in construction of
2028 // pre-main-post loop sequence.
2029 // When nonnull, the clone and original are side-by-side, both are
2030 // dominated by the side_by_side_idom node. Used in construction of
2031 // unswitched loops.
2032 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2033 CloneLoopMode mode, Node* side_by_side_idom) {
2034
2035 LoopNode* head = loop->_head->as_Loop();
2036 head->verify_strip_mined(1);
2037
2038 if (C->do_vector_loop() && PrintOpto) {
2039 const char* mname = C->method()->name()->as_quoted_ascii();
2040 if (mname != NULL) {
2041 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2042 }
2043 }
2044
2045 CloneMap& cm = C->clone_map();
2046 Dict* dict = cm.dict();
2047 if (C->do_vector_loop()) {
2048 cm.set_clone_idx(cm.max_gen()+1);
2049 #ifndef PRODUCT
2050 if (PrintOpto) {
2051 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2052 loop->dump_head();
2053 }
2054 #endif
2055 }
2056
2057 // Step 1: Clone the loop body. Make the old->new mapping.
2058 uint i;
2059 for( i = 0; i < loop->_body.size(); i++ ) {
2060 Node *old = loop->_body.at(i);
2061 Node *nnn = old->clone();
2062 old_new.map( old->_idx, nnn );
2063 if (C->do_vector_loop()) {
2064 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
2065 }
2066 _igvn.register_new_node_with_optimizer(nnn);
2067 }
2068
2069 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2070
2071 // Step 2: Fix the edges in the new body. If the old input is outside the
2072 // loop use it. If the old input is INside the loop, use the corresponding
2073 // new node instead.
2074 for( i = 0; i < loop->_body.size(); i++ ) {
2075 Node *old = loop->_body.at(i);
2076 Node *nnn = old_new[old->_idx];
2077 // Fix CFG/Loop controlling the new node
2078 if (has_ctrl(old)) {
2079 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2080 } else {
2081 set_loop(nnn, outer_loop->_parent);
2082 if (old->outcnt() > 0) {
2083 set_idom( nnn, old_new[idom(old)->_idx], dd );
2084 }
2085 }
2086 // Correct edges to the new node
2087 for( uint j = 0; j < nnn->req(); j++ ) {
2088 Node *n = nnn->in(j);
2089 if( n ) {
2090 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
2091 if( loop->is_member( old_in_loop ) )
2092 nnn->set_req(j, old_new[n->_idx]);
2093 }
2094 }
2095 _igvn.hash_find_insert(nnn);
2096 }
2097
2098 ResourceArea *area = Thread::current()->resource_area();
2099 Node_List extra_data_nodes(area); // data nodes in the outer strip mined loop
2100 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2101
2102 // Step 3: Now fix control uses. Loop varying control uses have already
2103 // been fixed up (as part of all input edges in Step 2). Loop invariant
2104 // control uses must be either an IfFalse or an IfTrue. Make a merge
2105 // point to merge the old and new IfFalse/IfTrue nodes; make the use
2106 // refer to this.
2107 Node_List worklist(area);
2108 uint new_counter = C->unique();
2109 for( i = 0; i < loop->_body.size(); i++ ) {
2110 Node* old = loop->_body.at(i);
2111 if( !old->is_CFG() ) continue;
2112
2113 // Copy uses to a worklist, so I can munge the def-use info
2114 // with impunity.
2115 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2116 worklist.push(old->fast_out(j));
2117
2118 while( worklist.size() ) { // Visit all uses
2119 Node *use = worklist.pop();
2120 if (!has_node(use)) continue; // Ignore dead nodes
2121 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2122 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
2123 // Both OLD and USE are CFG nodes here.
2124 assert( use->is_Proj(), "" );
2125 Node* nnn = old_new[old->_idx];
2126
2127 Node* newuse = NULL;
2128 if (head->is_strip_mined() && mode != IgnoreStripMined) {
2129 CountedLoopNode* cl = head->as_CountedLoop();
2130 CountedLoopEndNode* cle = cl->loopexit();
2131 Node* cle_out = cle->proj_out_or_null(false);
2132 if (use == cle_out) {
2133 IfNode* le = cl->outer_loop_end();
2134 use = le->proj_out(false);
2135 use_loop = get_loop(use);
2136 if (mode == CloneIncludesStripMined) {
2137 nnn = old_new[le->_idx];
2138 } else {
2139 newuse = old_new[cle_out->_idx];
2140 }
2141 }
2142 }
2143 if (newuse == NULL) {
2144 newuse = use->clone();
2145 }
2146
2147 // Clone the loop exit control projection
2148 if (C->do_vector_loop()) {
2149 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2150 }
2151 newuse->set_req(0,nnn);
2152 _igvn.register_new_node_with_optimizer(newuse);
2153 set_loop(newuse, use_loop);
2154 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2155
2156 // We need a Region to merge the exit from the peeled body and the
2157 // exit from the old loop body.
2158 RegionNode *r = new RegionNode(3);
2159 // Map the old use to the new merge point
2160 old_new.map( use->_idx, r );
2161 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2162 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2163
2164 // The original user of 'use' uses 'r' instead.
2165 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2166 Node* useuse = use->last_out(l);
2167 _igvn.rehash_node_delayed(useuse);
2168 uint uses_found = 0;
2169 if( useuse->in(0) == use ) {
2170 useuse->set_req(0, r);
2171 uses_found++;
2172 if( useuse->is_CFG() ) {
2173 assert( dom_depth(useuse) > dd_r, "" );
2174 set_idom(useuse, r, dom_depth(useuse));
2175 }
2176 }
2177 for( uint k = 1; k < useuse->req(); k++ ) {
2178 if( useuse->in(k) == use ) {
2179 useuse->set_req(k, r);
2180 uses_found++;
2181 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2182 assert(dom_depth(useuse) > dd_r , "");
2183 set_idom(useuse, r, dom_depth(useuse));
2184 }
2185 }
2186 }
2187 l -= uses_found; // we deleted 1 or more copies of this edge
2188 }
2189
2190 // Now finish up 'r'
2191 r->set_req( 1, newuse );
2192 r->set_req( 2, use );
2193 _igvn.register_new_node_with_optimizer(r);
2194 set_loop(r, use_loop);
2195 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2196 } // End of if a loop-exit test
2197 }
2198 }
2199
2200 // Step 4: If loop-invariant use is not control, it must be dominated by a
2201 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2202 // there if needed. Make a Phi there merging old and new used values.
2203 Node_List *split_if_set = NULL;
2204 Node_List *split_bool_set = NULL;
2205 Node_List *split_cex_set = NULL;
2206 for( i = 0; i < loop->_body.size(); i++ ) {
2207 Node* old = loop->_body.at(i);
2208 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2209 split_bool_set, split_cex_set, worklist, new_counter,
2210 mode);
2211 }
2212
2213 for (i = 0; i < extra_data_nodes.size(); i++) {
2214 Node* old = extra_data_nodes.at(i);
2215 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2216 split_bool_set, split_cex_set, worklist, new_counter,
2217 mode);
2218 }
2219
2220 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2221 // the loop uses a condition set in the loop. The original IF probably
2222 // takes control from one or more OLD Regions (which in turn get from NEW
2223 // Regions). In any case, there will be a set of Phis for each merge point
2224 // from the IF up to where the original BOOL def exists the loop.
2225 if (split_if_set) {
2226 while (split_if_set->size()) {
2227 Node *iff = split_if_set->pop();
2228 if (iff->in(1)->is_Phi()) {
2229 Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2230 _igvn.replace_input_of(iff, 1, b);
2231 }
2232 }
2233 }
2234 if (split_bool_set) {
2235 while (split_bool_set->size()) {
2236 Node *b = split_bool_set->pop();
2237 Node *phi = b->in(1);
2238 assert(phi->is_Phi(), "");
2239 CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2240 _igvn.replace_input_of(b, 1, cmp);
2241 }
2242 }
2243 if (split_cex_set) {
2244 while (split_cex_set->size()) {
2245 Node *b = split_cex_set->pop();
2246 assert(b->in(0)->is_Region(), "");
2247 assert(b->in(1)->is_Phi(), "");
2248 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2249 split_up(b, b->in(0), NULL);
2250 }
2251 }
2252
2253 }
2254
2255
2256 //---------------------- stride_of_possible_iv -------------------------------------
2257 // Looks for an iff/bool/comp with one operand of the compare
2258 // being a cycle involving an add and a phi,
2259 // with an optional truncation (left-shift followed by a right-shift)
2260 // of the add. Returns zero if not an iv.
2261 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2262 Node* trunc1 = NULL;
2263 Node* trunc2 = NULL;
2264 const TypeInt* ttype = NULL;
2265 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2266 return 0;
2267 }
2268 BoolNode* bl = iff->in(1)->as_Bool();
2269 Node* cmp = bl->in(1);
2270 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2271 return 0;
2272 }
2273 // Must have an invariant operand
2274 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2275 return 0;
2276 }
2277 Node* add2 = NULL;
2278 Node* cmp1 = cmp->in(1);
2279 if (cmp1->is_Phi()) {
2280 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2281 Node* phi = cmp1;
2282 for (uint i = 1; i < phi->req(); i++) {
2283 Node* in = phi->in(i);
2284 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2285 &trunc1, &trunc2, &ttype);
2286 if (add && add->in(1) == phi) {
2287 add2 = add->in(2);
2288 break;
2289 }
2290 }
2291 } else {
2292 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2293 Node* addtrunc = cmp1;
2294 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2295 &trunc1, &trunc2, &ttype);
2296 if (add && add->in(1)->is_Phi()) {
2297 Node* phi = add->in(1);
2298 for (uint i = 1; i < phi->req(); i++) {
2299 if (phi->in(i) == addtrunc) {
2300 add2 = add->in(2);
2301 break;
2302 }
2303 }
2304 }
2305 }
2306 if (add2 != NULL) {
2307 const TypeInt* add2t = _igvn.type(add2)->is_int();
2308 if (add2t->is_con()) {
2309 return add2t->get_con();
2310 }
2311 }
2312 return 0;
2313 }
2314
2315
2316 //---------------------- stay_in_loop -------------------------------------
2317 // Return the (unique) control output node that's in the loop (if it exists.)
2318 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2319 Node* unique = NULL;
2320 if (!n) return NULL;
2321 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2322 Node* use = n->fast_out(i);
2323 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2324 if (unique != NULL) {
2325 return NULL;
2326 }
2327 unique = use;
2328 }
2329 }
2330 return unique;
2331 }
2332
2333 //------------------------------ register_node -------------------------------------
2334 // Utility to register node "n" with PhaseIdealLoop
2335 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2336 _igvn.register_new_node_with_optimizer(n);
2337 loop->_body.push(n);
2338 if (n->is_CFG()) {
2339 set_loop(n, loop);
2340 set_idom(n, pred, ddepth);
2341 } else {
2342 set_ctrl(n, pred);
2343 }
2344 }
2345
2346 //------------------------------ proj_clone -------------------------------------
2347 // Utility to create an if-projection
2348 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2349 ProjNode* c = p->clone()->as_Proj();
2350 c->set_req(0, iff);
2351 return c;
2352 }
2353
2354 //------------------------------ short_circuit_if -------------------------------------
2355 // Force the iff control output to be the live_proj
2356 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2357 guarantee(live_proj != NULL, "null projection");
2358 int proj_con = live_proj->_con;
2359 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2360 Node *con = _igvn.intcon(proj_con);
2361 set_ctrl(con, C->root());
2362 if (iff) {
2363 iff->set_req(1, con);
2364 }
2365 return con;
2366 }
2367
2368 //------------------------------ insert_if_before_proj -------------------------------------
2369 // Insert a new if before an if projection (* - new node)
2370 //
2371 // before
2372 // if(test)
2373 // / \
2374 // v v
2375 // other-proj proj (arg)
2376 //
2377 // after
2378 // if(test)
2379 // / \
2380 // / v
2381 // | * proj-clone
2382 // v |
2383 // other-proj v
2384 // * new_if(relop(cmp[IU](left,right)))
2385 // / \
2386 // v v
2387 // * new-proj proj
2388 // (returned)
2389 //
2390 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2391 IfNode* iff = proj->in(0)->as_If();
2392 IdealLoopTree *loop = get_loop(proj);
2393 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2394 int ddepth = dom_depth(proj);
2395
2396 _igvn.rehash_node_delayed(iff);
2397 _igvn.rehash_node_delayed(proj);
2398
2399 proj->set_req(0, NULL); // temporary disconnect
2400 ProjNode* proj2 = proj_clone(proj, iff);
2401 register_node(proj2, loop, iff, ddepth);
2402
2403 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2404 register_node(cmp, loop, proj2, ddepth);
2405
2406 BoolNode* bol = new BoolNode(cmp, relop);
2407 register_node(bol, loop, proj2, ddepth);
2408
2409 int opcode = iff->Opcode();
2410 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2411 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2412 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2413 register_node(new_if, loop, proj2, ddepth);
2414
2415 proj->set_req(0, new_if); // reattach
2416 set_idom(proj, new_if, ddepth);
2417
2418 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2419 guarantee(new_exit != NULL, "null exit node");
2420 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2421
2422 return new_exit;
2423 }
2424
2425 //------------------------------ insert_region_before_proj -------------------------------------
2426 // Insert a region before an if projection (* - new node)
2427 //
2428 // before
2429 // if(test)
2430 // / |
2431 // v |
2432 // proj v
2433 // other-proj
2434 //
2435 // after
2436 // if(test)
2437 // / |
2438 // v |
2439 // * proj-clone v
2440 // | other-proj
2441 // v
2442 // * new-region
2443 // |
2444 // v
2445 // * dum_if
2446 // / \
2447 // v \
2448 // * dum-proj v
2449 // proj
2450 //
2451 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2452 IfNode* iff = proj->in(0)->as_If();
2453 IdealLoopTree *loop = get_loop(proj);
2454 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2455 int ddepth = dom_depth(proj);
2456
2457 _igvn.rehash_node_delayed(iff);
2458 _igvn.rehash_node_delayed(proj);
2459
2460 proj->set_req(0, NULL); // temporary disconnect
2461 ProjNode* proj2 = proj_clone(proj, iff);
2462 register_node(proj2, loop, iff, ddepth);
2463
2464 RegionNode* reg = new RegionNode(2);
2465 reg->set_req(1, proj2);
2466 register_node(reg, loop, iff, ddepth);
2467
2468 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2469 register_node(dum_if, loop, reg, ddepth);
2470
2471 proj->set_req(0, dum_if); // reattach
2472 set_idom(proj, dum_if, ddepth);
2473
2474 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2475 register_node(dum_proj, loop, dum_if, ddepth);
2476
2477 return reg;
2478 }
2479
2480 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2481 // Clone a signed compare loop exit from an unsigned compare and
2482 // insert it before the unsigned cmp on the stay-in-loop path.
2483 // All new nodes inserted in the dominator tree between the original
2484 // if and it's projections. The original if test is replaced with
2485 // a constant to force the stay-in-loop path.
2486 //
2487 // This is done to make sure that the original if and it's projections
2488 // still dominate the same set of control nodes, that the ctrl() relation
2489 // from data nodes to them is preserved, and that their loop nesting is
2490 // preserved.
2491 //
2492 // before
2493 // if(i <u limit) unsigned compare loop exit
2494 // / |
2495 // v v
2496 // exit-proj stay-in-loop-proj
2497 //
2498 // after
2499 // if(stay-in-loop-const) original if
2500 // / |
2501 // / v
2502 // / if(i < limit) new signed test
2503 // / / |
2504 // / / v
2505 // / / if(i <u limit) new cloned unsigned test
2506 // / / / |
2507 // v v v |
2508 // region |
2509 // | |
2510 // dum-if |
2511 // / | |
2512 // ether | |
2513 // v v
2514 // exit-proj stay-in-loop-proj
2515 //
2516 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2517 const bool Signed = true;
2518 const bool Unsigned = false;
2519
2520 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2521 if (bol->_test._test != BoolTest::lt) return NULL;
2522 CmpNode* cmpu = bol->in(1)->as_Cmp();
2523 if (cmpu->Opcode() != Op_CmpU) return NULL;
2524 int stride = stride_of_possible_iv(if_cmpu);
2525 if (stride == 0) return NULL;
2526
2527 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2528 guarantee(lp_proj != NULL, "null loop node");
2529
2530 ProjNode* lp_continue = lp_proj->as_Proj();
2531 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2532
2533 Node* limit = NULL;
2534 if (stride > 0) {
2535 limit = cmpu->in(2);
2536 } else {
2537 limit = _igvn.makecon(TypeInt::ZERO);
2538 set_ctrl(limit, C->root());
2539 }
2540 // Create a new region on the exit path
2541 RegionNode* reg = insert_region_before_proj(lp_exit);
2542 guarantee(reg != NULL, "null region node");
2543
2544 // Clone the if-cmpu-true-false using a signed compare
2545 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2546 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2547 reg->add_req(cmpi_exit);
2548
2549 // Clone the if-cmpu-true-false
2550 BoolTest::mask rel_u = bol->_test._test;
2551 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2552 reg->add_req(cmpu_exit);
2553
2554 // Force original if to stay in loop.
2555 short_circuit_if(if_cmpu, lp_continue);
2556
2557 return cmpi_exit->in(0)->as_If();
2558 }
2559
2560 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2561 // Remove a previously inserted signed compare loop exit.
2562 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2563 Node* lp_proj = stay_in_loop(if_cmp, loop);
2564 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2565 stay_in_loop(lp_proj, loop)->is_If() &&
2566 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2567 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2568 set_ctrl(con, C->root());
2569 if_cmp->set_req(1, con);
2570 }
2571
2572 //------------------------------ scheduled_nodelist -------------------------------------
2573 // Create a post order schedule of nodes that are in the
2574 // "member" set. The list is returned in "sched".
2575 // The first node in "sched" is the loop head, followed by
2576 // nodes which have no inputs in the "member" set, and then
2577 // followed by the nodes that have an immediate input dependence
2578 // on a node in "sched".
2579 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2580
2581 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2582 Arena *a = Thread::current()->resource_area();
2583 VectorSet visited(a);
2584 Node_Stack nstack(a, loop->_body.size());
2585
2586 Node* n = loop->_head; // top of stack is cached in "n"
2587 uint idx = 0;
2588 visited.set(n->_idx);
2589
2590 // Initially push all with no inputs from within member set
2591 for(uint i = 0; i < loop->_body.size(); i++ ) {
2592 Node *elt = loop->_body.at(i);
2593 if (member.test(elt->_idx)) {
2594 bool found = false;
2595 for (uint j = 0; j < elt->req(); j++) {
2596 Node* def = elt->in(j);
2597 if (def && member.test(def->_idx) && def != elt) {
2598 found = true;
2599 break;
2600 }
2601 }
2602 if (!found && elt != loop->_head) {
2603 nstack.push(n, idx);
2604 n = elt;
2605 assert(!visited.test(n->_idx), "not seen yet");
2606 visited.set(n->_idx);
2607 }
2608 }
2609 }
2610
2611 // traverse out's that are in the member set
2612 while (true) {
2613 if (idx < n->outcnt()) {
2614 Node* use = n->raw_out(idx);
2615 idx++;
2616 if (!visited.test_set(use->_idx)) {
2617 if (member.test(use->_idx)) {
2618 nstack.push(n, idx);
2619 n = use;
2620 idx = 0;
2621 }
2622 }
2623 } else {
2624 // All outputs processed
2625 sched.push(n);
2626 if (nstack.is_empty()) break;
2627 n = nstack.node();
2628 idx = nstack.index();
2629 nstack.pop();
2630 }
2631 }
2632 }
2633
2634
2635 //------------------------------ has_use_in_set -------------------------------------
2636 // Has a use in the vector set
2637 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2638 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2639 Node* use = n->fast_out(j);
2640 if (vset.test(use->_idx)) {
2641 return true;
2642 }
2643 }
2644 return false;
2645 }
2646
2647
2648 //------------------------------ has_use_internal_to_set -------------------------------------
2649 // Has use internal to the vector set (ie. not in a phi at the loop head)
2650 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2651 Node* head = loop->_head;
2652 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2653 Node* use = n->fast_out(j);
2654 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2655 return true;
2656 }
2657 }
2658 return false;
2659 }
2660
2661
2662 //------------------------------ clone_for_use_outside_loop -------------------------------------
2663 // clone "n" for uses that are outside of loop
2664 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2665 int cloned = 0;
2666 assert(worklist.size() == 0, "should be empty");
2667 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2668 Node* use = n->fast_out(j);
2669 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2670 worklist.push(use);
2671 }
2672 }
2673 while( worklist.size() ) {
2674 Node *use = worklist.pop();
2675 if (!has_node(use) || use->in(0) == C->top()) continue;
2676 uint j;
2677 for (j = 0; j < use->req(); j++) {
2678 if (use->in(j) == n) break;
2679 }
2680 assert(j < use->req(), "must be there");
2681
2682 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2683 Node* n_clone = n->clone();
2684 _igvn.replace_input_of(use, j, n_clone);
2685 cloned++;
2686 Node* use_c;
2687 if (!use->is_Phi()) {
2688 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2689 } else {
2690 // Use in a phi is considered a use in the associated predecessor block
2691 use_c = use->in(0)->in(j);
2692 }
2693 set_ctrl(n_clone, use_c);
2694 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2695 get_loop(use_c)->_body.push(n_clone);
2696 _igvn.register_new_node_with_optimizer(n_clone);
2697 #ifndef PRODUCT
2698 if (TracePartialPeeling) {
2699 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2700 }
2701 #endif
2702 }
2703 return cloned;
2704 }
2705
2706
2707 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2708 // clone "n" for special uses that are in the not_peeled region.
2709 // If these def-uses occur in separate blocks, the code generator
2710 // marks the method as not compilable. For example, if a "BoolNode"
2711 // is in a different basic block than the "IfNode" that uses it, then
2712 // the compilation is aborted in the code generator.
2713 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2714 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2715 if (n->is_Phi() || n->is_Load()) {
2716 return;
2717 }
2718 assert(worklist.size() == 0, "should be empty");
2719 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2720 Node* use = n->fast_out(j);
2721 if ( not_peel.test(use->_idx) &&
2722 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2723 use->in(1) == n) {
2724 worklist.push(use);
2725 }
2726 }
2727 if (worklist.size() > 0) {
2728 // clone "n" and insert it between inputs of "n" and the use
2729 Node* n_clone = n->clone();
2730 loop->_body.push(n_clone);
2731 _igvn.register_new_node_with_optimizer(n_clone);
2732 set_ctrl(n_clone, get_ctrl(n));
2733 sink_list.push(n_clone);
2734 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2735 #ifndef PRODUCT
2736 if (TracePartialPeeling) {
2737 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2738 }
2739 #endif
2740 while( worklist.size() ) {
2741 Node *use = worklist.pop();
2742 _igvn.rehash_node_delayed(use);
2743 for (uint j = 1; j < use->req(); j++) {
2744 if (use->in(j) == n) {
2745 use->set_req(j, n_clone);
2746 }
2747 }
2748 }
2749 }
2750 }
2751
2752
2753 //------------------------------ insert_phi_for_loop -------------------------------------
2754 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2755 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2756 Node *phi = PhiNode::make(lp, back_edge_val);
2757 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2758 // Use existing phi if it already exists
2759 Node *hit = _igvn.hash_find_insert(phi);
2760 if( hit == NULL ) {
2761 _igvn.register_new_node_with_optimizer(phi);
2762 set_ctrl(phi, lp);
2763 } else {
2764 // Remove the new phi from the graph and use the hit
2765 _igvn.remove_dead_node(phi);
2766 phi = hit;
2767 }
2768 _igvn.replace_input_of(use, idx, phi);
2769 }
2770
2771 #ifdef ASSERT
2772 //------------------------------ is_valid_loop_partition -------------------------------------
2773 // Validate the loop partition sets: peel and not_peel
2774 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2775 VectorSet& not_peel ) {
2776 uint i;
2777 // Check that peel_list entries are in the peel set
2778 for (i = 0; i < peel_list.size(); i++) {
2779 if (!peel.test(peel_list.at(i)->_idx)) {
2780 return false;
2781 }
2782 }
2783 // Check at loop members are in one of peel set or not_peel set
2784 for (i = 0; i < loop->_body.size(); i++ ) {
2785 Node *def = loop->_body.at(i);
2786 uint di = def->_idx;
2787 // Check that peel set elements are in peel_list
2788 if (peel.test(di)) {
2789 if (not_peel.test(di)) {
2790 return false;
2791 }
2792 // Must be in peel_list also
2793 bool found = false;
2794 for (uint j = 0; j < peel_list.size(); j++) {
2795 if (peel_list.at(j)->_idx == di) {
2796 found = true;
2797 break;
2798 }
2799 }
2800 if (!found) {
2801 return false;
2802 }
2803 } else if (not_peel.test(di)) {
2804 if (peel.test(di)) {
2805 return false;
2806 }
2807 } else {
2808 return false;
2809 }
2810 }
2811 return true;
2812 }
2813
2814 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2815 // Ensure a use outside of loop is of the right form
2816 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2817 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2818 return (use->is_Phi() &&
2819 use_c->is_Region() && use_c->req() == 3 &&
2820 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2821 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2822 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2823 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2824 }
2825
2826 //------------------------------ is_valid_clone_loop_form -------------------------------------
2827 // Ensure that all uses outside of loop are of the right form
2828 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2829 uint orig_exit_idx, uint clone_exit_idx) {
2830 uint len = peel_list.size();
2831 for (uint i = 0; i < len; i++) {
2832 Node *def = peel_list.at(i);
2833
2834 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2835 Node *use = def->fast_out(j);
2836 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2837 if (!loop->is_member(get_loop(use_c))) {
2838 // use is not in the loop, check for correct structure
2839 if (use->in(0) == def) {
2840 // Okay
2841 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2842 return false;
2843 }
2844 }
2845 }
2846 }
2847 return true;
2848 }
2849 #endif
2850
2851 //------------------------------ partial_peel -------------------------------------
2852 // Partially peel (aka loop rotation) the top portion of a loop (called
2853 // the peel section below) by cloning it and placing one copy just before
2854 // the new loop head and the other copy at the bottom of the new loop.
2855 //
2856 // before after where it came from
2857 //
2858 // stmt1 stmt1
2859 // loop: stmt2 clone
2860 // stmt2 if condA goto exitA clone
2861 // if condA goto exitA new_loop: new
2862 // stmt3 stmt3 clone
2863 // if !condB goto loop if condB goto exitB clone
2864 // exitB: stmt2 orig
2865 // stmt4 if !condA goto new_loop orig
2866 // exitA: goto exitA
2867 // exitB:
2868 // stmt4
2869 // exitA:
2870 //
2871 // Step 1: find the cut point: an exit test on probable
2872 // induction variable.
2873 // Step 2: schedule (with cloning) operations in the peel
2874 // section that can be executed after the cut into
2875 // the section that is not peeled. This may need
2876 // to clone operations into exit blocks. For
2877 // instance, a reference to A[i] in the not-peel
2878 // section and a reference to B[i] in an exit block
2879 // may cause a left-shift of i by 2 to be placed
2880 // in the peel block. This step will clone the left
2881 // shift into the exit block and sink the left shift
2882 // from the peel to the not-peel section.
2883 // Step 3: clone the loop, retarget the control, and insert
2884 // phis for values that are live across the new loop
2885 // head. This is very dependent on the graph structure
2886 // from clone_loop. It creates region nodes for
2887 // exit control and associated phi nodes for values
2888 // flow out of the loop through that exit. The region
2889 // node is dominated by the clone's control projection.
2890 // So the clone's peel section is placed before the
2891 // new loop head, and the clone's not-peel section is
2892 // forms the top part of the new loop. The original
2893 // peel section forms the tail of the new loop.
2894 // Step 4: update the dominator tree and recompute the
2895 // dominator depth.
2896 //
2897 // orig
2898 //
2899 // stmt1
2900 // |
2901 // v
2902 // loop predicate
2903 // |
2904 // v
2905 // loop<----+
2906 // | |
2907 // stmt2 |
2908 // | |
2909 // v |
2910 // ifA |
2911 // / | |
2912 // v v |
2913 // false true ^ <-- last_peel
2914 // / | |
2915 // / ===|==cut |
2916 // / stmt3 | <-- first_not_peel
2917 // / | |
2918 // | v |
2919 // v ifB |
2920 // exitA: / \ |
2921 // / \ |
2922 // v v |
2923 // false true |
2924 // / \ |
2925 // / ----+
2926 // |
2927 // v
2928 // exitB:
2929 // stmt4
2930 //
2931 //
2932 // after clone loop
2933 //
2934 // stmt1
2935 // |
2936 // v
2937 // loop predicate
2938 // / \
2939 // clone / \ orig
2940 // / \
2941 // / \
2942 // v v
2943 // +---->loop loop<----+
2944 // | | | |
2945 // | stmt2 stmt2 |
2946 // | | | |
2947 // | v v |
2948 // | ifA ifA |
2949 // | | \ / | |
2950 // | v v v v |
2951 // ^ true false false true ^ <-- last_peel
2952 // | | ^ \ / | |
2953 // | cut==|== \ \ / ===|==cut |
2954 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2955 // | | dom | | | |
2956 // | v \ 1v v2 v |
2957 // | ifB regionA ifB |
2958 // | / \ | / \ |
2959 // | / \ v / \ |
2960 // | v v exitA: v v |
2961 // | true false false true |
2962 // | / ^ \ / \ |
2963 // +---- \ \ / ----+
2964 // dom \ /
2965 // \ 1v v2
2966 // regionB
2967 // |
2968 // v
2969 // exitB:
2970 // stmt4
2971 //
2972 //
2973 // after partial peel
2974 //
2975 // stmt1
2976 // |
2977 // v
2978 // loop predicate
2979 // /
2980 // clone / orig
2981 // / TOP
2982 // / \
2983 // v v
2984 // TOP->loop loop----+
2985 // | | |
2986 // stmt2 stmt2 |
2987 // | | |
2988 // v v |
2989 // ifA ifA |
2990 // | \ / | |
2991 // v v v v |
2992 // true false false true | <-- last_peel
2993 // | ^ \ / +------|---+
2994 // +->newloop \ \ / === ==cut | |
2995 // | stmt3 \ \ / TOP | |
2996 // | | dom | | stmt3 | | <-- first_not_peel
2997 // | v \ 1v v2 v | |
2998 // | ifB regionA ifB ^ v
2999 // | / \ | / \ | |
3000 // | / \ v / \ | |
3001 // | v v exitA: v v | |
3002 // | true false false true | |
3003 // | / ^ \ / \ | |
3004 // | | \ \ / v | |
3005 // | | dom \ / TOP | |
3006 // | | \ 1v v2 | |
3007 // ^ v regionB | |
3008 // | | | | |
3009 // | | v ^ v
3010 // | | exitB: | |
3011 // | | stmt4 | |
3012 // | +------------>-----------------+ |
3013 // | |
3014 // +-----------------<---------------------+
3015 //
3016 //
3017 // final graph
3018 //
3019 // stmt1
3020 // |
3021 // v
3022 // loop predicate
3023 // |
3024 // v
3025 // stmt2 clone
3026 // |
3027 // v
3028 // ........> ifA clone
3029 // : / |
3030 // dom / |
3031 // : v v
3032 // : false true
3033 // : | |
3034 // : | v
3035 // : | newloop<-----+
3036 // : | | |
3037 // : | stmt3 clone |
3038 // : | | |
3039 // : | v |
3040 // : | ifB |
3041 // : | / \ |
3042 // : | v v |
3043 // : | false true |
3044 // : | | | |
3045 // : | v stmt2 |
3046 // : | exitB: | |
3047 // : | stmt4 v |
3048 // : | ifA orig |
3049 // : | / \ |
3050 // : | / \ |
3051 // : | v v |
3052 // : | false true |
3053 // : | / \ |
3054 // : v v -----+
3055 // RegionA
3056 // |
3057 // v
3058 // exitA
3059 //
3060 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3061
3062 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3063 if (!loop->_head->is_Loop()) {
3064 return false;
3065 }
3066 LoopNode *head = loop->_head->as_Loop();
3067
3068 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3069 return false;
3070 }
3071
3072 // Check for complex exit control
3073 for (uint ii = 0; ii < loop->_body.size(); ii++) {
3074 Node *n = loop->_body.at(ii);
3075 int opc = n->Opcode();
3076 if (n->is_Call() ||
3077 opc == Op_Catch ||
3078 opc == Op_CatchProj ||
3079 opc == Op_Jump ||
3080 opc == Op_JumpProj) {
3081 #ifndef PRODUCT
3082 if (TracePartialPeeling) {
3083 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3084 }
3085 #endif
3086 return false;
3087 }
3088 }
3089
3090 int dd = dom_depth(head);
3091
3092 // Step 1: find cut point
3093
3094 // Walk up dominators to loop head looking for first loop exit
3095 // which is executed on every path thru loop.
3096 IfNode *peel_if = NULL;
3097 IfNode *peel_if_cmpu = NULL;
3098
3099 Node *iff = loop->tail();
3100 while (iff != head) {
3101 if (iff->is_If()) {
3102 Node *ctrl = get_ctrl(iff->in(1));
3103 if (ctrl->is_top()) return false; // Dead test on live IF.
3104 // If loop-varying exit-test, check for induction variable
3105 if (loop->is_member(get_loop(ctrl)) &&
3106 loop->is_loop_exit(iff) &&
3107 is_possible_iv_test(iff)) {
3108 Node* cmp = iff->in(1)->in(1);
3109 if (cmp->Opcode() == Op_CmpI) {
3110 peel_if = iff->as_If();
3111 } else {
3112 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3113 peel_if_cmpu = iff->as_If();
3114 }
3115 }
3116 }
3117 iff = idom(iff);
3118 }
3119
3120 // Prefer signed compare over unsigned compare.
3121 IfNode* new_peel_if = NULL;
3122 if (peel_if == NULL) {
3123 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3124 return false; // No peel point found
3125 }
3126 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3127 if (new_peel_if == NULL) {
3128 return false; // No peel point found
3129 }
3130 peel_if = new_peel_if;
3131 }
3132 Node* last_peel = stay_in_loop(peel_if, loop);
3133 Node* first_not_peeled = stay_in_loop(last_peel, loop);
3134 if (first_not_peeled == NULL || first_not_peeled == head) {
3135 return false;
3136 }
3137
3138 #ifndef PRODUCT
3139 if (TraceLoopOpts) {
3140 tty->print("PartialPeel ");
3141 loop->dump_head();
3142 }
3143
3144 if (TracePartialPeeling) {
3145 tty->print_cr("before partial peel one iteration");
3146 Node_List wl;
3147 Node* t = head->in(2);
3148 while (true) {
3149 wl.push(t);
3150 if (t == head) break;
3151 t = idom(t);
3152 }
3153 while (wl.size() > 0) {
3154 Node* tt = wl.pop();
3155 tt->dump();
3156 if (tt == last_peel) tty->print_cr("-- cut --");
3157 }
3158 }
3159 #endif
3160 ResourceArea *area = Thread::current()->resource_area();
3161 VectorSet peel(area);
3162 VectorSet not_peel(area);
3163 Node_List peel_list(area);
3164 Node_List worklist(area);
3165 Node_List sink_list(area);
3166
3167 if (!may_require_nodes(loop->est_loop_clone_sz(2))) {
3168 return false;
3169 }
3170
3171 // Set of cfg nodes to peel are those that are executable from
3172 // the head through last_peel.
3173 assert(worklist.size() == 0, "should be empty");
3174 worklist.push(head);
3175 peel.set(head->_idx);
3176 while (worklist.size() > 0) {
3177 Node *n = worklist.pop();
3178 if (n != last_peel) {
3179 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3180 Node* use = n->fast_out(j);
3181 if (use->is_CFG() &&
3182 loop->is_member(get_loop(use)) &&
3183 !peel.test_set(use->_idx)) {
3184 worklist.push(use);
3185 }
3186 }
3187 }
3188 }
3189
3190 // Set of non-cfg nodes to peel are those that are control
3191 // dependent on the cfg nodes.
3192 uint i;
3193 for(i = 0; i < loop->_body.size(); i++ ) {
3194 Node *n = loop->_body.at(i);
3195 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3196 if (peel.test(n_c->_idx)) {
3197 peel.set(n->_idx);
3198 } else {
3199 not_peel.set(n->_idx);
3200 }
3201 }
3202
3203 // Step 2: move operations from the peeled section down into the
3204 // not-peeled section
3205
3206 // Get a post order schedule of nodes in the peel region
3207 // Result in right-most operand.
3208 scheduled_nodelist(loop, peel, peel_list );
3209
3210 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3211
3212 // For future check for too many new phis
3213 uint old_phi_cnt = 0;
3214 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3215 Node* use = head->fast_out(j);
3216 if (use->is_Phi()) old_phi_cnt++;
3217 }
3218
3219 #ifndef PRODUCT
3220 if (TracePartialPeeling) {
3221 tty->print_cr("\npeeled list");
3222 }
3223 #endif
3224
3225 // Evacuate nodes in peel region into the not_peeled region if possible
3226 uint new_phi_cnt = 0;
3227 uint cloned_for_outside_use = 0;
3228 for (i = 0; i < peel_list.size();) {
3229 Node* n = peel_list.at(i);
3230 #ifndef PRODUCT
3231 if (TracePartialPeeling) n->dump();
3232 #endif
3233 bool incr = true;
3234 if ( !n->is_CFG() ) {
3235
3236 if ( has_use_in_set(n, not_peel) ) {
3237
3238 // If not used internal to the peeled region,
3239 // move "n" from peeled to not_peeled region.
3240
3241 if ( !has_use_internal_to_set(n, peel, loop) ) {
3242
3243 // if not pinned and not a load (which maybe anti-dependent on a store)
3244 // and not a CMove (Matcher expects only bool->cmove).
3245 if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
3246 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
3247 sink_list.push(n);
3248 peel >>= n->_idx; // delete n from peel set.
3249 not_peel <<= n->_idx; // add n to not_peel set.
3250 peel_list.remove(i);
3251 incr = false;
3252 #ifndef PRODUCT
3253 if (TracePartialPeeling) {
3254 tty->print_cr("sink to not_peeled region: %d newbb: %d",
3255 n->_idx, get_ctrl(n)->_idx);
3256 }
3257 #endif
3258 }
3259 } else {
3260 // Otherwise check for special def-use cases that span
3261 // the peel/not_peel boundary such as bool->if
3262 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
3263 new_phi_cnt++;
3264 }
3265 }
3266 }
3267 if (incr) i++;
3268 }
3269
3270 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
3271 #ifndef PRODUCT
3272 if (TracePartialPeeling) {
3273 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
3274 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3275 }
3276 #endif
3277 if (new_peel_if != NULL) {
3278 remove_cmpi_loop_exit(new_peel_if, loop);
3279 }
3280 // Inhibit more partial peeling on this loop
3281 assert(!head->is_partial_peel_loop(), "not partial peeled");
3282 head->mark_partial_peel_failed();
3283 if (cloned_for_outside_use > 0) {
3284 // Terminate this round of loop opts because
3285 // the graph outside this loop was changed.
3286 C->set_major_progress();
3287 return true;
3288 }
3289 return false;
3290 }
3291
3292 // Step 3: clone loop, retarget control, and insert new phis
3293
3294 // Create new loop head for new phis and to hang
3295 // the nodes being moved (sinked) from the peel region.
3296 LoopNode* new_head = new LoopNode(last_peel, last_peel);
3297 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3298 _igvn.register_new_node_with_optimizer(new_head);
3299 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3300 _igvn.replace_input_of(first_not_peeled, 0, new_head);
3301 set_loop(new_head, loop);
3302 loop->_body.push(new_head);
3303 not_peel.set(new_head->_idx);
3304 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3305 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3306
3307 while (sink_list.size() > 0) {
3308 Node* n = sink_list.pop();
3309 set_ctrl(n, new_head);
3310 }
3311
3312 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3313
3314 clone_loop(loop, old_new, dd, IgnoreStripMined);
3315
3316 const uint clone_exit_idx = 1;
3317 const uint orig_exit_idx = 2;
3318 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
3319
3320 Node* head_clone = old_new[head->_idx];
3321 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
3322 Node* orig_tail_clone = head_clone->in(2);
3323
3324 // Add phi if "def" node is in peel set and "use" is not
3325
3326 for(i = 0; i < peel_list.size(); i++ ) {
3327 Node *def = peel_list.at(i);
3328 if (!def->is_CFG()) {
3329 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3330 Node *use = def->fast_out(j);
3331 if (has_node(use) && use->in(0) != C->top() &&
3332 (!peel.test(use->_idx) ||
3333 (use->is_Phi() && use->in(0) == head)) ) {
3334 worklist.push(use);
3335 }
3336 }
3337 while( worklist.size() ) {
3338 Node *use = worklist.pop();
3339 for (uint j = 1; j < use->req(); j++) {
3340 Node* n = use->in(j);
3341 if (n == def) {
3342
3343 // "def" is in peel set, "use" is not in peel set
3344 // or "use" is in the entry boundary (a phi) of the peel set
3345
3346 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3347
3348 if ( loop->is_member(get_loop( use_c )) ) {
3349 // use is in loop
3350 if (old_new[use->_idx] != NULL) { // null for dead code
3351 Node* use_clone = old_new[use->_idx];
3352 _igvn.replace_input_of(use, j, C->top());
3353 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3354 }
3355 } else {
3356 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3357 // use is not in the loop, check if the live range includes the cut
3358 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3359 if (not_peel.test(lp_if->_idx)) {
3360 assert(j == orig_exit_idx, "use from original loop");
3361 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3362 }
3363 }
3364 }
3365 }
3366 }
3367 }
3368 }
3369
3370 // Step 3b: retarget control
3371
3372 // Redirect control to the new loop head if a cloned node in
3373 // the not_peeled region has control that points into the peeled region.
3374 // This necessary because the cloned peeled region will be outside
3375 // the loop.
3376 // from to
3377 // cloned-peeled <---+
3378 // new_head_clone: | <--+
3379 // cloned-not_peeled in(0) in(0)
3380 // orig-peeled
3381
3382 for(i = 0; i < loop->_body.size(); i++ ) {
3383 Node *n = loop->_body.at(i);
3384 if (!n->is_CFG() && n->in(0) != NULL &&
3385 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3386 Node* n_clone = old_new[n->_idx];
3387 _igvn.replace_input_of(n_clone, 0, new_head_clone);
3388 }
3389 }
3390
3391 // Backedge of the surviving new_head (the clone) is original last_peel
3392 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3393
3394 // Cut first node in original not_peel set
3395 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
3396 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
3397 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
3398
3399 // Copy head_clone back-branch info to original head
3400 // and remove original head's loop entry and
3401 // clone head's back-branch
3402 _igvn.rehash_node_delayed(head); // Multiple edge updates
3403 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
3404 head->set_req(LoopNode::LoopBackControl, C->top());
3405 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3406
3407 // Similarly modify the phis
3408 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3409 Node* use = head->fast_out(k);
3410 if (use->is_Phi() && use->outcnt() > 0) {
3411 Node* use_clone = old_new[use->_idx];
3412 _igvn.rehash_node_delayed(use); // Multiple edge updates
3413 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
3414 use->set_req(LoopNode::LoopBackControl, C->top());
3415 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3416 }
3417 }
3418
3419 // Step 4: update dominator tree and dominator depth
3420
3421 set_idom(head, orig_tail_clone, dd);
3422 recompute_dom_depth();
3423
3424 // Inhibit more partial peeling on this loop
3425 new_head_clone->set_partial_peel_loop();
3426 C->set_major_progress();
3427 loop->record_for_igvn();
3428
3429 #ifndef PRODUCT
3430 if (TracePartialPeeling) {
3431 tty->print_cr("\nafter partial peel one iteration");
3432 Node_List wl(area);
3433 Node* t = last_peel;
3434 while (true) {
3435 wl.push(t);
3436 if (t == head_clone) break;
3437 t = idom(t);
3438 }
3439 while (wl.size() > 0) {
3440 Node* tt = wl.pop();
3441 if (tt == head) tty->print_cr("orig head");
3442 else if (tt == new_head_clone) tty->print_cr("new head");
3443 else if (tt == head_clone) tty->print_cr("clone head");
3444 tt->dump();
3445 }
3446 }
3447 #endif
3448 return true;
3449 }
3450
3451 //------------------------------reorg_offsets----------------------------------
3452 // Reorganize offset computations to lower register pressure. Mostly
3453 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3454 // then alive with the post-incremented trip counter forcing an extra
3455 // register move)
3456 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3457 // Perform it only for canonical counted loops.
3458 // Loop's shape could be messed up by iteration_split_impl.
3459 if (!loop->_head->is_CountedLoop())
3460 return;
3461 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3462 return;
3463
3464 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3465 CountedLoopEndNode *cle = cl->loopexit();
3466 Node *exit = cle->proj_out(false);
3467 Node *phi = cl->phi();
3468
3469 // Check for the special case when using the pre-incremented trip-counter on
3470 // the fall-out path (forces the pre-incremented and post-incremented trip
3471 // counter to be live at the same time). Fix this by adjusting to use the
3472 // post-increment trip counter.
3473
3474 bool progress = true;
3475 while (progress) {
3476 progress = false;
3477 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3478 Node* use = phi->fast_out(i); // User of trip-counter
3479 if (!has_ctrl(use)) continue;
3480 Node *u_ctrl = get_ctrl(use);
3481 if (use->is_Phi()) {
3482 u_ctrl = NULL;
3483 for (uint j = 1; j < use->req(); j++)
3484 if (use->in(j) == phi)
3485 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3486 }
3487 IdealLoopTree *u_loop = get_loop(u_ctrl);
3488 // Look for loop-invariant use
3489 if (u_loop == loop) continue;
3490 if (loop->is_member(u_loop)) continue;
3491 // Check that use is live out the bottom. Assuming the trip-counter
3492 // update is right at the bottom, uses of of the loop middle are ok.
3493 if (dom_lca(exit, u_ctrl) != exit) continue;
3494 // Hit! Refactor use to use the post-incremented tripcounter.
3495 // Compute a post-increment tripcounter.
3496 Node* c = exit;
3497 if (cl->is_strip_mined()) {
3498 IdealLoopTree* outer_loop = get_loop(cl->outer_loop());
3499 if (!outer_loop->is_member(u_loop)) {
3500 c = cl->outer_loop_exit();
3501 }
3502 }
3503 Node *opaq = new Opaque2Node(C, cle->incr());
3504 register_new_node(opaq, c);
3505 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3506 set_ctrl(neg_stride, C->root());
3507 Node *post = new AddINode(opaq, neg_stride);
3508 register_new_node(post, c);
3509 _igvn.rehash_node_delayed(use);
3510 for (uint j = 1; j < use->req(); j++) {
3511 if (use->in(j) == phi)
3512 use->set_req(j, post);
3513 }
3514 // Since DU info changed, rerun loop
3515 progress = true;
3516 break;
3517 }
3518 }
3519
3520 }