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