1 /*
2 * Copyright (c) 1999, 2018, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/callnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/castnode.hpp"
35 #include "opto/divnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/matcher.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/movenode.hpp"
40 #include "opto/opaquenode.hpp"
41 #include "opto/rootnode.hpp"
42 #include "opto/subnode.hpp"
43 #include "utilities/macros.hpp"
44 #if INCLUDE_ZGC
45 #include "gc/z/c2/zBarrierSetC2.hpp"
46 #endif
47
48 //=============================================================================
49 //------------------------------split_thru_phi---------------------------------
50 // Split Node 'n' through merge point if there is enough win.
51 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
52 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
53 // ConvI2L may have type information on it which is unsafe to push up
54 // so disable this for now
55 return NULL;
56 }
57
58 // Splitting range check CastIIs through a loop induction Phi can
59 // cause new Phis to be created that are left unrelated to the loop
60 // induction Phi and prevent optimizations (vectorization)
61 if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
62 region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
63 return NULL;
64 }
65
66 int wins = 0;
67 assert(!n->is_CFG(), "");
68 assert(region->is_Region(), "");
69
70 const Type* type = n->bottom_type();
71 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
72 Node *phi;
73 if (t_oop != NULL && t_oop->is_known_instance_field()) {
74 int iid = t_oop->instance_id();
75 int index = C->get_alias_index(t_oop);
76 int offset = t_oop->offset();
77 phi = new PhiNode(region, type, NULL, iid, index, offset);
78 } else {
79 phi = PhiNode::make_blank(region, n);
80 }
81 uint old_unique = C->unique();
82 for (uint i = 1; i < region->req(); i++) {
83 Node *x;
84 Node* the_clone = NULL;
85 if (region->in(i) == C->top()) {
86 x = C->top(); // Dead path? Use a dead data op
87 } else {
88 x = n->clone(); // Else clone up the data op
89 the_clone = x; // Remember for possible deletion.
90 // Alter data node to use pre-phi inputs
91 if (n->in(0) == region)
92 x->set_req( 0, region->in(i) );
93 for (uint j = 1; j < n->req(); j++) {
94 Node *in = n->in(j);
95 if (in->is_Phi() && in->in(0) == region)
96 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
97 }
98 }
99 // Check for a 'win' on some paths
100 const Type *t = x->Value(&_igvn);
101
102 bool singleton = t->singleton();
103
104 // A TOP singleton indicates that there are no possible values incoming
105 // along a particular edge. In most cases, this is OK, and the Phi will
106 // be eliminated later in an Ideal call. However, we can't allow this to
107 // happen if the singleton occurs on loop entry, as the elimination of
108 // the PhiNode may cause the resulting node to migrate back to a previous
109 // loop iteration.
110 if (singleton && t == Type::TOP) {
111 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
112 // irreducible loop may not be indicated by an affirmative is_Loop());
113 // therefore, the only top we can split thru a phi is on a backedge of
114 // a loop.
115 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
116 }
117
118 if (singleton) {
119 wins++;
120 x = ((PhaseGVN&)_igvn).makecon(t);
121 } else {
122 // We now call Identity to try to simplify the cloned node.
123 // Note that some Identity methods call phase->type(this).
124 // Make sure that the type array is big enough for
125 // our new node, even though we may throw the node away.
126 // (Note: This tweaking with igvn only works because x is a new node.)
127 _igvn.set_type(x, t);
128 // If x is a TypeNode, capture any more-precise type permanently into Node
129 // otherwise it will be not updated during igvn->transform since
130 // igvn->type(x) is set to x->Value() already.
131 x->raise_bottom_type(t);
132 Node *y = x->Identity(&_igvn);
133 if (y != x) {
134 wins++;
135 x = y;
136 } else {
137 y = _igvn.hash_find(x);
138 if (y) {
139 wins++;
140 x = y;
141 } else {
142 // Else x is a new node we are keeping
143 // We do not need register_new_node_with_optimizer
144 // because set_type has already been called.
145 _igvn._worklist.push(x);
146 }
147 }
148 }
149 if (x != the_clone && the_clone != NULL)
150 _igvn.remove_dead_node(the_clone);
151 phi->set_req( i, x );
152 }
153 // Too few wins?
154 if (wins <= policy) {
155 _igvn.remove_dead_node(phi);
156 return NULL;
157 }
158
159 // Record Phi
160 register_new_node( phi, region );
161
162 for (uint i2 = 1; i2 < phi->req(); i2++) {
163 Node *x = phi->in(i2);
164 // If we commoned up the cloned 'x' with another existing Node,
165 // the existing Node picks up a new use. We need to make the
166 // existing Node occur higher up so it dominates its uses.
167 Node *old_ctrl;
168 IdealLoopTree *old_loop;
169
170 if (x->is_Con()) {
171 // Constant's control is always root.
172 set_ctrl(x, C->root());
173 continue;
174 }
175 // The occasional new node
176 if (x->_idx >= old_unique) { // Found a new, unplaced node?
177 old_ctrl = NULL;
178 old_loop = NULL; // Not in any prior loop
179 } else {
180 old_ctrl = get_ctrl(x);
181 old_loop = get_loop(old_ctrl); // Get prior loop
182 }
183 // New late point must dominate new use
184 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
185 if (new_ctrl == old_ctrl) // Nothing is changed
186 continue;
187
188 IdealLoopTree *new_loop = get_loop(new_ctrl);
189
190 // Don't move x into a loop if its uses are
191 // outside of loop. Otherwise x will be cloned
192 // for each use outside of this loop.
193 IdealLoopTree *use_loop = get_loop(region);
194 if (!new_loop->is_member(use_loop) &&
195 (old_loop == NULL || !new_loop->is_member(old_loop))) {
196 // Take early control, later control will be recalculated
197 // during next iteration of loop optimizations.
198 new_ctrl = get_early_ctrl(x);
199 new_loop = get_loop(new_ctrl);
200 }
201 // Set new location
202 set_ctrl(x, new_ctrl);
203 // If changing loop bodies, see if we need to collect into new body
204 if (old_loop != new_loop) {
205 if (old_loop && !old_loop->_child)
206 old_loop->_body.yank(x);
207 if (!new_loop->_child)
208 new_loop->_body.push(x); // Collect body info
209 }
210 }
211
212 return phi;
213 }
214
215 //------------------------------dominated_by------------------------------------
216 // Replace the dominated test with an obvious true or false. Place it on the
217 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
218 // live path up to the dominating control.
219 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
220 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
221
222 // prevdom is the dominating projection of the dominating test.
223 assert( iff->is_If(), "" );
224 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
225 int pop = prevdom->Opcode();
226 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
227 if (flip) {
228 if (pop == Op_IfTrue)
229 pop = Op_IfFalse;
230 else
231 pop = Op_IfTrue;
232 }
233 // 'con' is set to true or false to kill the dominated test.
234 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
235 set_ctrl(con, C->root()); // Constant gets a new use
236 // Hack the dominated test
237 _igvn.replace_input_of(iff, 1, con);
238
239 // If I dont have a reachable TRUE and FALSE path following the IfNode then
240 // I can assume this path reaches an infinite loop. In this case it's not
241 // important to optimize the data Nodes - either the whole compilation will
242 // be tossed or this path (and all data Nodes) will go dead.
243 if (iff->outcnt() != 2) return;
244
245 // Make control-dependent data Nodes on the live path (path that will remain
246 // once the dominated IF is removed) become control-dependent on the
247 // dominating projection.
248 Node* dp = iff->as_If()->proj_out_or_null(pop == Op_IfTrue);
249
250 // Loop predicates may have depending checks which should not
251 // be skipped. For example, range check predicate has two checks
252 // for lower and upper bounds.
253 if (dp == NULL)
254 return;
255
256 ProjNode* dp_proj = dp->as_Proj();
257 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
258 if (exclude_loop_predicate &&
259 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
260 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
261 // If this is a range check (IfNode::is_range_check), do not
262 // reorder because Compile::allow_range_check_smearing might have
263 // changed the check.
264 return; // Let IGVN transformation change control dependence.
265 }
266
267 IdealLoopTree *old_loop = get_loop(dp);
268
269 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
270 Node* cd = dp->fast_out(i); // Control-dependent node
271 if (cd->depends_only_on_test()) {
272 assert(cd->in(0) == dp, "");
273 _igvn.replace_input_of(cd, 0, prevdom);
274 set_early_ctrl(cd);
275 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
276 if (old_loop != new_loop) {
277 if (!old_loop->_child) old_loop->_body.yank(cd);
278 if (!new_loop->_child) new_loop->_body.push(cd);
279 }
280 --i;
281 --imax;
282 }
283 }
284 }
285
286 //------------------------------has_local_phi_input----------------------------
287 // Return TRUE if 'n' has Phi inputs from its local block and no other
288 // block-local inputs (all non-local-phi inputs come from earlier blocks)
289 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
290 Node *n_ctrl = get_ctrl(n);
291 // See if some inputs come from a Phi in this block, or from before
292 // this block.
293 uint i;
294 for( i = 1; i < n->req(); i++ ) {
295 Node *phi = n->in(i);
296 if( phi->is_Phi() && phi->in(0) == n_ctrl )
297 break;
298 }
299 if( i >= n->req() )
300 return NULL; // No Phi inputs; nowhere to clone thru
301
302 // Check for inputs created between 'n' and the Phi input. These
303 // must split as well; they have already been given the chance
304 // (courtesy of a post-order visit) and since they did not we must
305 // recover the 'cost' of splitting them by being very profitable
306 // when splitting 'n'. Since this is unlikely we simply give up.
307 for( i = 1; i < n->req(); i++ ) {
308 Node *m = n->in(i);
309 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
310 // We allow the special case of AddP's with no local inputs.
311 // This allows us to split-up address expressions.
312 if (m->is_AddP() &&
313 get_ctrl(m->in(2)) != n_ctrl &&
314 get_ctrl(m->in(3)) != n_ctrl) {
315 // Move the AddP up to dominating point
316 Node* c = find_non_split_ctrl(idom(n_ctrl));
317 if (c->is_OuterStripMinedLoop()) {
318 c->as_Loop()->verify_strip_mined(1);
319 c = c->in(LoopNode::EntryControl);
320 }
321 set_ctrl_and_loop(m, c);
322 continue;
323 }
324 return NULL;
325 }
326 assert(m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
327 }
328
329 return n_ctrl;
330 }
331
332 //------------------------------remix_address_expressions----------------------
333 // Rework addressing expressions to get the most loop-invariant stuff
334 // moved out. We'd like to do all associative operators, but it's especially
335 // important (common) to do address expressions.
336 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
337 if (!has_ctrl(n)) return NULL;
338 Node *n_ctrl = get_ctrl(n);
339 IdealLoopTree *n_loop = get_loop(n_ctrl);
340
341 // See if 'n' mixes loop-varying and loop-invariant inputs and
342 // itself is loop-varying.
343
344 // Only interested in binary ops (and AddP)
345 if( n->req() < 3 || n->req() > 4 ) return NULL;
346
347 Node *n1_ctrl = get_ctrl(n->in( 1));
348 Node *n2_ctrl = get_ctrl(n->in( 2));
349 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
350 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
351 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
352 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
353
354 // Does one of my inputs spin in a tighter loop than self?
355 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
356 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
357 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
358 return NULL; // Leave well enough alone
359
360 // Is at least one of my inputs loop-invariant?
361 if( n1_loop == n_loop &&
362 n2_loop == n_loop &&
363 n3_loop == n_loop )
364 return NULL; // No loop-invariant inputs
365
366
367 int n_op = n->Opcode();
368
369 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
370 if( n_op == Op_LShiftI ) {
371 // Scale is loop invariant
372 Node *scale = n->in(2);
373 Node *scale_ctrl = get_ctrl(scale);
374 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
375 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
376 return NULL;
377 const TypeInt *scale_t = scale->bottom_type()->isa_int();
378 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
379 return NULL; // Dont bother with byte/short masking
380 // Add must vary with loop (else shift would be loop-invariant)
381 Node *add = n->in(1);
382 Node *add_ctrl = get_ctrl(add);
383 IdealLoopTree *add_loop = get_loop(add_ctrl);
384 //assert( n_loop == add_loop, "" );
385 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
386
387 // Convert I-V into I+ (0-V); same for V-I
388 if( add->Opcode() == Op_SubI &&
389 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
390 Node *zero = _igvn.intcon(0);
391 set_ctrl(zero, C->root());
392 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
393 register_new_node( neg, get_ctrl(add->in(2) ) );
394 add = new AddINode( add->in(1), neg );
395 register_new_node( add, add_ctrl );
396 }
397 if( add->Opcode() != Op_AddI ) return NULL;
398 // See if one add input is loop invariant
399 Node *add_var = add->in(1);
400 Node *add_var_ctrl = get_ctrl(add_var);
401 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
402 Node *add_invar = add->in(2);
403 Node *add_invar_ctrl = get_ctrl(add_invar);
404 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
405 if( add_var_loop == n_loop ) {
406 } else if( add_invar_loop == n_loop ) {
407 // Swap to find the invariant part
408 add_invar = add_var;
409 add_invar_ctrl = add_var_ctrl;
410 add_invar_loop = add_var_loop;
411 add_var = add->in(2);
412 Node *add_var_ctrl = get_ctrl(add_var);
413 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
414 } else // Else neither input is loop invariant
415 return NULL;
416 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
417 return NULL; // No invariant part of the add?
418
419 // Yes! Reshape address expression!
420 Node *inv_scale = new LShiftINode( add_invar, scale );
421 Node *inv_scale_ctrl =
422 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
423 add_invar_ctrl : scale_ctrl;
424 register_new_node( inv_scale, inv_scale_ctrl );
425 Node *var_scale = new LShiftINode( add_var, scale );
426 register_new_node( var_scale, n_ctrl );
427 Node *var_add = new AddINode( var_scale, inv_scale );
428 register_new_node( var_add, n_ctrl );
429 _igvn.replace_node( n, var_add );
430 return var_add;
431 }
432
433 // Replace (I+V) with (V+I)
434 if( n_op == Op_AddI ||
435 n_op == Op_AddL ||
436 n_op == Op_AddF ||
437 n_op == Op_AddD ||
438 n_op == Op_MulI ||
439 n_op == Op_MulL ||
440 n_op == Op_MulF ||
441 n_op == Op_MulD ) {
442 if( n2_loop == n_loop ) {
443 assert( n1_loop != n_loop, "" );
444 n->swap_edges(1, 2);
445 }
446 }
447
448 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
449 // but not if I2 is a constant.
450 if( n_op == Op_AddP ) {
451 if( n2_loop == n_loop && n3_loop != n_loop ) {
452 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
453 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
454 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
455 IdealLoopTree *n22loop = get_loop( n22_ctrl );
456 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
457 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
458 n23_loop == n_loop ) {
459 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
460 // Stuff new AddP in the loop preheader
461 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
462 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
463 register_new_node( add2, n_ctrl );
464 _igvn.replace_node( n, add2 );
465 return add2;
466 }
467 }
468 }
469
470 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
471 if (n2_loop != n_loop && n3_loop == n_loop) {
472 if (n->in(3)->Opcode() == Op_AddX) {
473 Node *V = n->in(3)->in(1);
474 Node *I = n->in(3)->in(2);
475 if (is_member(n_loop,get_ctrl(V))) {
476 } else {
477 Node *tmp = V; V = I; I = tmp;
478 }
479 if (!is_member(n_loop,get_ctrl(I))) {
480 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
481 // Stuff new AddP in the loop preheader
482 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
483 Node *add2 = new AddPNode(n->in(1), add1, V);
484 register_new_node(add2, n_ctrl);
485 _igvn.replace_node(n, add2);
486 return add2;
487 }
488 }
489 }
490 }
491
492 return NULL;
493 }
494
495 //------------------------------conditional_move-------------------------------
496 // Attempt to replace a Phi with a conditional move. We have some pretty
497 // strict profitability requirements. All Phis at the merge point must
498 // be converted, so we can remove the control flow. We need to limit the
499 // number of c-moves to a small handful. All code that was in the side-arms
500 // of the CFG diamond is now speculatively executed. This code has to be
501 // "cheap enough". We are pretty much limited to CFG diamonds that merge
502 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
503 Node *PhaseIdealLoop::conditional_move( Node *region ) {
504
505 assert(region->is_Region(), "sanity check");
506 if (region->req() != 3) return NULL;
507
508 // Check for CFG diamond
509 Node *lp = region->in(1);
510 Node *rp = region->in(2);
511 if (!lp || !rp) return NULL;
512 Node *lp_c = lp->in(0);
513 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
514 IfNode *iff = lp_c->as_If();
515
516 // Check for ops pinned in an arm of the diamond.
517 // Can't remove the control flow in this case
518 if (lp->outcnt() > 1) return NULL;
519 if (rp->outcnt() > 1) return NULL;
520
521 IdealLoopTree* r_loop = get_loop(region);
522 assert(r_loop == get_loop(iff), "sanity");
523 // Always convert to CMOVE if all results are used only outside this loop.
524 bool used_inside_loop = (r_loop == _ltree_root);
525
526 // Check profitability
527 int cost = 0;
528 int phis = 0;
529 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
530 Node *out = region->fast_out(i);
531 if (!out->is_Phi()) continue; // Ignore other control edges, etc
532 phis++;
533 PhiNode* phi = out->as_Phi();
534 BasicType bt = phi->type()->basic_type();
535 switch (bt) {
536 case T_DOUBLE:
537 case T_FLOAT:
538 if (C->use_cmove()) {
539 continue; //TODO: maybe we want to add some cost
540 }
541 cost += Matcher::float_cmove_cost(); // Could be very expensive
542 break;
543 case T_LONG: {
544 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
545 }
546 case T_INT: // These all CMOV fine
547 case T_ADDRESS: { // (RawPtr)
548 cost++;
549 break;
550 }
551 case T_NARROWOOP: // Fall through
552 case T_OBJECT: { // Base oops are OK, but not derived oops
553 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
554 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
555 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
556 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
557 // have a Phi for the base here that we convert to a CMOVE all is well
558 // and good. But if the base is dead, we'll not make a CMOVE. Later
559 // the allocator will have to produce a base by creating a CMOVE of the
560 // relevant bases. This puts the allocator in the business of
561 // manufacturing expensive instructions, generally a bad plan.
562 // Just Say No to Conditionally-Moved Derived Pointers.
563 if (tp && tp->offset() != 0)
564 return NULL;
565 cost++;
566 break;
567 }
568 default:
569 return NULL; // In particular, can't do memory or I/O
570 }
571 // Add in cost any speculative ops
572 for (uint j = 1; j < region->req(); j++) {
573 Node *proj = region->in(j);
574 Node *inp = phi->in(j);
575 if (get_ctrl(inp) == proj) { // Found local op
576 cost++;
577 // Check for a chain of dependent ops; these will all become
578 // speculative in a CMOV.
579 for (uint k = 1; k < inp->req(); k++)
580 if (get_ctrl(inp->in(k)) == proj)
581 cost += ConditionalMoveLimit; // Too much speculative goo
582 }
583 }
584 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
585 // This will likely Split-If, a higher-payoff operation.
586 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
587 Node* use = phi->fast_out(k);
588 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
589 cost += ConditionalMoveLimit;
590 // Is there a use inside the loop?
591 // Note: check only basic types since CMoveP is pinned.
592 if (!used_inside_loop && is_java_primitive(bt)) {
593 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
594 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
595 used_inside_loop = true;
596 }
597 }
598 }
599 }//for
600 Node* bol = iff->in(1);
601 assert(bol->Opcode() == Op_Bool, "");
602 int cmp_op = bol->in(1)->Opcode();
603 // It is expensive to generate flags from a float compare.
604 // Avoid duplicated float compare.
605 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
606
607 float infrequent_prob = PROB_UNLIKELY_MAG(3);
608 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
609 if (used_inside_loop) {
610 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
611
612 // BlockLayoutByFrequency optimization moves infrequent branch
613 // from hot path. No point in CMOV'ing in such case (110 is used
614 // instead of 100 to take into account not exactness of float value).
615 if (BlockLayoutByFrequency) {
616 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
617 }
618 }
619 // Check for highly predictable branch. No point in CMOV'ing if
620 // we are going to predict accurately all the time.
621 if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
622 //keep going
623 } else if (iff->_prob < infrequent_prob ||
624 iff->_prob > (1.0f - infrequent_prob))
625 return NULL;
626
627 // --------------
628 // Now replace all Phis with CMOV's
629 Node *cmov_ctrl = iff->in(0);
630 uint flip = (lp->Opcode() == Op_IfTrue);
631 Node_List wq;
632 while (1) {
633 PhiNode* phi = NULL;
634 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
635 Node *out = region->fast_out(i);
636 if (out->is_Phi()) {
637 phi = out->as_Phi();
638 break;
639 }
640 }
641 if (phi == NULL) break;
642 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
643 // Move speculative ops
644 wq.push(phi);
645 while (wq.size() > 0) {
646 Node *n = wq.pop();
647 for (uint j = 1; j < n->req(); j++) {
648 Node* m = n->in(j);
649 if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
650 #ifndef PRODUCT
651 if (PrintOpto && VerifyLoopOptimizations) {
652 tty->print(" speculate: ");
653 m->dump();
654 }
655 #endif
656 set_ctrl(m, cmov_ctrl);
657 wq.push(m);
658 }
659 }
660 }
661 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
662 register_new_node( cmov, cmov_ctrl );
663 _igvn.replace_node( phi, cmov );
664 #ifndef PRODUCT
665 if (TraceLoopOpts) {
666 tty->print("CMOV ");
667 r_loop->dump_head();
668 if (Verbose) {
669 bol->in(1)->dump(1);
670 cmov->dump(1);
671 }
672 }
673 if (VerifyLoopOptimizations) verify();
674 #endif
675 }
676
677 // The useless CFG diamond will fold up later; see the optimization in
678 // RegionNode::Ideal.
679 _igvn._worklist.push(region);
680
681 return iff->in(1);
682 }
683
684 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
685 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
686 Node* u = m->fast_out(i);
687 if (u->is_CFG()) {
688 if (u->Opcode() == Op_NeverBranch) {
689 u = ((NeverBranchNode*)u)->proj_out(0);
690 enqueue_cfg_uses(u, wq);
691 } else {
692 wq.push(u);
693 }
694 }
695 }
696 }
697
698 // Try moving a store out of a loop, right before the loop
699 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
700 // Store has to be first in the loop body
701 IdealLoopTree *n_loop = get_loop(n_ctrl);
702 if (n->is_Store() && n_loop != _ltree_root &&
703 n_loop->is_loop() && n_loop->_head->is_Loop() &&
704 n->in(0) != NULL) {
705 Node* address = n->in(MemNode::Address);
706 Node* value = n->in(MemNode::ValueIn);
707 Node* mem = n->in(MemNode::Memory);
708 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
709 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
710
711 // - address and value must be loop invariant
712 // - memory must be a memory Phi for the loop
713 // - Store must be the only store on this memory slice in the
714 // loop: if there's another store following this one then value
715 // written at iteration i by the second store could be overwritten
716 // at iteration i+n by the first store: it's not safe to move the
717 // first store out of the loop
718 // - nothing must observe the memory Phi: it guarantees no read
719 // before the store, we are also guaranteed the store post
720 // dominates the loop head (ignoring a possible early
721 // exit). Otherwise there would be extra Phi involved between the
722 // loop's Phi and the store.
723 // - there must be no early exit from the loop before the Store
724 // (such an exit most of the time would be an extra use of the
725 // memory Phi but sometimes is a bottom memory Phi that takes the
726 // store as input).
727
728 if (!n_loop->is_member(address_loop) &&
729 !n_loop->is_member(value_loop) &&
730 mem->is_Phi() && mem->in(0) == n_loop->_head &&
731 mem->outcnt() == 1 &&
732 mem->in(LoopNode::LoopBackControl) == n) {
733
734 assert(n_loop->_tail != NULL, "need a tail");
735 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
736
737 // Verify that there's no early exit of the loop before the store.
738 bool ctrl_ok = false;
739 {
740 // Follow control from loop head until n, we exit the loop or
741 // we reach the tail
742 ResourceMark rm;
743 Unique_Node_List wq;
744 wq.push(n_loop->_head);
745
746 for (uint next = 0; next < wq.size(); ++next) {
747 Node *m = wq.at(next);
748 if (m == n->in(0)) {
749 ctrl_ok = true;
750 continue;
751 }
752 assert(!has_ctrl(m), "should be CFG");
753 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
754 ctrl_ok = false;
755 break;
756 }
757 enqueue_cfg_uses(m, wq);
758 if (wq.size() > 10) {
759 ctrl_ok = false;
760 break;
761 }
762 }
763 }
764 if (ctrl_ok) {
765 // move the Store
766 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
767 _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
768 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
769 // Disconnect the phi now. An empty phi can confuse other
770 // optimizations in this pass of loop opts.
771 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
772 n_loop->_body.yank(mem);
773
774 set_ctrl_and_loop(n, n->in(0));
775
776 return n;
777 }
778 }
779 }
780 return NULL;
781 }
782
783 // Try moving a store out of a loop, right after the loop
784 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
785 if (n->is_Store() && n->in(0) != NULL) {
786 Node *n_ctrl = get_ctrl(n);
787 IdealLoopTree *n_loop = get_loop(n_ctrl);
788 // Store must be in a loop
789 if (n_loop != _ltree_root && !n_loop->_irreducible) {
790 Node* address = n->in(MemNode::Address);
791 Node* value = n->in(MemNode::ValueIn);
792 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
793 // address must be loop invariant
794 if (!n_loop->is_member(address_loop)) {
795 // Store must be last on this memory slice in the loop and
796 // nothing in the loop must observe it
797 Node* phi = NULL;
798 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
799 Node* u = n->fast_out(i);
800 if (has_ctrl(u)) { // control use?
801 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
802 if (!n_loop->is_member(u_loop)) {
803 continue;
804 }
805 if (u->is_Phi() && u->in(0) == n_loop->_head) {
806 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
807 // multiple phis on the same slice are possible
808 if (phi != NULL) {
809 return;
810 }
811 phi = u;
812 continue;
813 }
814 }
815 return;
816 }
817 if (phi != NULL) {
818 // Nothing in the loop before the store (next iteration)
819 // must observe the stored value
820 bool mem_ok = true;
821 {
822 ResourceMark rm;
823 Unique_Node_List wq;
824 wq.push(phi);
825 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
826 Node *m = wq.at(next);
827 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
828 Node* u = m->fast_out(i);
829 if (u->is_Store() || u->is_Phi()) {
830 if (u != n) {
831 wq.push(u);
832 mem_ok = (wq.size() <= 10);
833 }
834 } else {
835 mem_ok = false;
836 break;
837 }
838 }
839 }
840 }
841 if (mem_ok) {
842 // Move the store out of the loop if the LCA of all
843 // users (except for the phi) is outside the loop.
844 Node* hook = new Node(1);
845 _igvn.rehash_node_delayed(phi);
846 int count = phi->replace_edge(n, hook);
847 assert(count > 0, "inconsistent phi");
848
849 // Compute latest point this store can go
850 Node* lca = get_late_ctrl(n, get_ctrl(n));
851 if (n_loop->is_member(get_loop(lca))) {
852 // LCA is in the loop - bail out
853 _igvn.replace_node(hook, n);
854 return;
855 }
856 #ifdef ASSERT
857 if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
858 assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
859 n_loop->_head->as_Loop()->verify_strip_mined(1);
860 Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
861 IdealLoopTree* outer_loop = get_loop(outer);
862 assert(n_loop->_parent == outer_loop, "broken loop tree");
863 assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
864 }
865 #endif
866
867 // Move store out of the loop
868 _igvn.replace_node(hook, n->in(MemNode::Memory));
869 _igvn.replace_input_of(n, 0, lca);
870 set_ctrl_and_loop(n, lca);
871
872 // Disconnect the phi now. An empty phi can confuse other
873 // optimizations in this pass of loop opts..
874 if (phi->in(LoopNode::LoopBackControl) == phi) {
875 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
876 n_loop->_body.yank(phi);
877 }
878 }
879 }
880 }
881 }
882 }
883 }
884
885 //------------------------------split_if_with_blocks_pre-----------------------
886 // Do the real work in a non-recursive function. Data nodes want to be
887 // cloned in the pre-order so they can feed each other nicely.
888 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
889 // Cloning these guys is unlikely to win
890 int n_op = n->Opcode();
891 if( n_op == Op_MergeMem ) return n;
892 if( n->is_Proj() ) return n;
893 // Do not clone-up CmpFXXX variations, as these are always
894 // followed by a CmpI
895 if( n->is_Cmp() ) return n;
896 // Attempt to use a conditional move instead of a phi/branch
897 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
898 Node *cmov = conditional_move( n );
899 if( cmov ) return cmov;
900 }
901 if( n->is_CFG() || n->is_LoadStore() )
902 return n;
903 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
904 n_op == Op_Opaque2 ) {
905 if( !C->major_progress() ) // If chance of no more loop opts...
906 _igvn._worklist.push(n); // maybe we'll remove them
907 return n;
908 }
909
910 if( n->is_Con() ) return n; // No cloning for Con nodes
911
912 Node *n_ctrl = get_ctrl(n);
913 if( !n_ctrl ) return n; // Dead node
914
915 Node* res = try_move_store_before_loop(n, n_ctrl);
916 if (res != NULL) {
917 return n;
918 }
919
920 // Attempt to remix address expressions for loop invariants
921 Node *m = remix_address_expressions( n );
922 if( m ) return m;
923
924 if (n->is_ConstraintCast()) {
925 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
926 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
927 // Node control inputs don't necessarily agree with loop control info (due to
928 // transformations happened in between), thus additional dominance check is needed
929 // to keep loop info valid.
930 if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
931 _igvn.replace_node(n, dom_cast);
932 return dom_cast;
933 }
934 }
935
936 // Determine if the Node has inputs from some local Phi.
937 // Returns the block to clone thru.
938 Node *n_blk = has_local_phi_input( n );
939 if( !n_blk ) return n;
940
941 // Do not clone the trip counter through on a CountedLoop
942 // (messes up the canonical shape).
943 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
944
945 // Check for having no control input; not pinned. Allow
946 // dominating control.
947 if (n->in(0)) {
948 Node *dom = idom(n_blk);
949 if (dom_lca(n->in(0), dom) != n->in(0)) {
950 return n;
951 }
952 }
953 // Policy: when is it profitable. You must get more wins than
954 // policy before it is considered profitable. Policy is usually 0,
955 // so 1 win is considered profitable. Big merges will require big
956 // cloning, so get a larger policy.
957 int policy = n_blk->req() >> 2;
958
959 // If the loop is a candidate for range check elimination,
960 // delay splitting through it's phi until a later loop optimization
961 if (n_blk->is_CountedLoop()) {
962 IdealLoopTree *lp = get_loop(n_blk);
963 if (lp && lp->_rce_candidate) {
964 return n;
965 }
966 }
967
968 // Use same limit as split_if_with_blocks_post
969 if( C->live_nodes() > 35000 ) return n; // Method too big
970
971 // Split 'n' through the merge point if it is profitable
972 Node *phi = split_thru_phi( n, n_blk, policy );
973 if (!phi) return n;
974
975 // Found a Phi to split thru!
976 // Replace 'n' with the new phi
977 _igvn.replace_node( n, phi );
978 // Moved a load around the loop, 'en-registering' something.
979 if (n_blk->is_Loop() && n->is_Load() &&
980 !phi->in(LoopNode::LoopBackControl)->is_Load())
981 C->set_major_progress();
982
983 return phi;
984 }
985
986 static bool merge_point_too_heavy(Compile* C, Node* region) {
987 // Bail out if the region and its phis have too many users.
988 int weight = 0;
989 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
990 weight += region->fast_out(i)->outcnt();
991 }
992 int nodes_left = C->max_node_limit() - C->live_nodes();
993 if (weight * 8 > nodes_left) {
994 if (PrintOpto) {
995 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
996 }
997 return true;
998 } else {
999 return false;
1000 }
1001 }
1002
1003 static bool merge_point_safe(Node* region) {
1004 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1005 // having a PhiNode input. This sidesteps the dangerous case where the split
1006 // ConvI2LNode may become TOP if the input Value() does not
1007 // overlap the ConvI2L range, leaving a node which may not dominate its
1008 // uses.
1009 // A better fix for this problem can be found in the BugTraq entry, but
1010 // expediency for Mantis demands this hack.
1011 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1012 // split_if_with_blocks from splitting a block because we could not move around
1013 // the FastLockNode.
1014 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1015 Node* n = region->fast_out(i);
1016 if (n->is_Phi()) {
1017 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1018 Node* m = n->fast_out(j);
1019 if (m->is_FastLock())
1020 return false;
1021 #ifdef _LP64
1022 if (m->Opcode() == Op_ConvI2L)
1023 return false;
1024 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1025 return false;
1026 }
1027 #endif
1028 }
1029 }
1030 }
1031 return true;
1032 }
1033
1034
1035 //------------------------------place_near_use---------------------------------
1036 // Place some computation next to use but not inside inner loops.
1037 // For inner loop uses move it to the preheader area.
1038 Node *PhaseIdealLoop::place_near_use(Node *useblock) const {
1039 IdealLoopTree *u_loop = get_loop( useblock );
1040 if (u_loop->_irreducible) {
1041 return useblock;
1042 }
1043 if (u_loop->_child) {
1044 if (useblock == u_loop->_head && u_loop->_head->is_OuterStripMinedLoop()) {
1045 return u_loop->_head->in(LoopNode::EntryControl);
1046 }
1047 return useblock;
1048 }
1049 return u_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1050 }
1051
1052
1053 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1054 if (!n->is_If() || n->is_CountedLoopEnd()) {
1055 return false;
1056 }
1057 if (!n->in(0)->is_Region()) {
1058 return false;
1059 }
1060 Node* region = n->in(0);
1061 Node* dom = idom(region);
1062 if (!dom->is_If() || dom->in(1) != n->in(1)) {
1063 return false;
1064 }
1065 IfNode* dom_if = dom->as_If();
1066 Node* proj_true = dom_if->proj_out(1);
1067 Node* proj_false = dom_if->proj_out(0);
1068
1069 for (uint i = 1; i < region->req(); i++) {
1070 if (is_dominator(proj_true, region->in(i))) {
1071 continue;
1072 }
1073 if (is_dominator(proj_false, region->in(i))) {
1074 continue;
1075 }
1076 return false;
1077 }
1078
1079 return true;
1080 }
1081
1082 bool PhaseIdealLoop::can_split_if(Node *n_ctrl) {
1083 if (C->live_nodes() > 35000) {
1084 return false; // Method too big
1085 }
1086
1087 // Do not do 'split-if' if irreducible loops are present.
1088 if (_has_irreducible_loops) {
1089 return false;
1090 }
1091
1092 if (merge_point_too_heavy(C, n_ctrl)) {
1093 return false;
1094 }
1095
1096 // Do not do 'split-if' if some paths are dead. First do dead code
1097 // elimination and then see if its still profitable.
1098 for (uint i = 1; i < n_ctrl->req(); i++) {
1099 if (n_ctrl->in(i) == C->top()) {
1100 return false;
1101 }
1102 }
1103
1104 // If trying to do a 'Split-If' at the loop head, it is only
1105 // profitable if the cmp folds up on BOTH paths. Otherwise we
1106 // risk peeling a loop forever.
1107
1108 // CNC - Disabled for now. Requires careful handling of loop
1109 // body selection for the cloned code. Also, make sure we check
1110 // for any input path not being in the same loop as n_ctrl. For
1111 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1112 // because the alternative loop entry points won't be converted
1113 // into LoopNodes.
1114 IdealLoopTree *n_loop = get_loop(n_ctrl);
1115 for (uint j = 1; j < n_ctrl->req(); j++) {
1116 if (get_loop(n_ctrl->in(j)) != n_loop) {
1117 return false;
1118 }
1119 }
1120
1121 // Check for safety of the merge point.
1122 if (!merge_point_safe(n_ctrl)) {
1123 return false;
1124 }
1125
1126 return true;
1127 }
1128
1129 //------------------------------split_if_with_blocks_post----------------------
1130 // Do the real work in a non-recursive function. CFG hackery wants to be
1131 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1132 // info.
1133 void PhaseIdealLoop::split_if_with_blocks_post(Node *n, bool last_round) {
1134
1135 // Cloning Cmp through Phi's involves the split-if transform.
1136 // FastLock is not used by an If
1137 if (n->is_Cmp() && !n->is_FastLock() && !last_round) {
1138 Node *n_ctrl = get_ctrl(n);
1139 // Determine if the Node has inputs from some local Phi.
1140 // Returns the block to clone thru.
1141 Node *n_blk = has_local_phi_input(n);
1142 if (n_blk != n_ctrl) {
1143 return;
1144 }
1145
1146 if (!can_split_if(n_ctrl)) {
1147 return;
1148 }
1149
1150 if (n->outcnt() != 1) {
1151 return; // Multiple bool's from 1 compare?
1152 }
1153 Node *bol = n->unique_out();
1154 assert(bol->is_Bool(), "expect a bool here");
1155 if (bol->outcnt() != 1) {
1156 return;// Multiple branches from 1 compare?
1157 }
1158 Node *iff = bol->unique_out();
1159
1160 // Check some safety conditions
1161 if (iff->is_If()) { // Classic split-if?
1162 if (iff->in(0) != n_ctrl) {
1163 return; // Compare must be in same blk as if
1164 }
1165 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1166 // Can't split CMove with different control edge.
1167 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1168 return;
1169 }
1170 if (get_ctrl(iff->in(2)) == n_ctrl ||
1171 get_ctrl(iff->in(3)) == n_ctrl) {
1172 return; // Inputs not yet split-up
1173 }
1174 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1175 return; // Loop-invar test gates loop-varying CMOVE
1176 }
1177 } else {
1178 return; // some other kind of node, such as an Allocate
1179 }
1180
1181 // When is split-if profitable? Every 'win' on means some control flow
1182 // goes dead, so it's almost always a win.
1183 int policy = 0;
1184 // Split compare 'n' through the merge point if it is profitable
1185 Node *phi = split_thru_phi( n, n_ctrl, policy);
1186 if (!phi) {
1187 return;
1188 }
1189
1190 // Found a Phi to split thru!
1191 // Replace 'n' with the new phi
1192 _igvn.replace_node(n, phi);
1193
1194 // Now split the bool up thru the phi
1195 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1196 guarantee(bolphi != NULL, "null boolean phi node");
1197
1198 _igvn.replace_node(bol, bolphi);
1199 assert(iff->in(1) == bolphi, "");
1200
1201 if (bolphi->Value(&_igvn)->singleton()) {
1202 return;
1203 }
1204
1205 // Conditional-move? Must split up now
1206 if (!iff->is_If()) {
1207 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1208 _igvn.replace_node(iff, cmovphi);
1209 return;
1210 }
1211
1212 // Now split the IF
1213 do_split_if(iff);
1214 return;
1215 }
1216
1217 // Two identical ifs back to back can be merged
1218 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1219 Node *n_ctrl = n->in(0);
1220 PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1221 IfNode* dom_if = idom(n_ctrl)->as_If();
1222 Node* proj_true = dom_if->proj_out(1);
1223 Node* proj_false = dom_if->proj_out(0);
1224 Node* con_true = _igvn.makecon(TypeInt::ONE);
1225 Node* con_false = _igvn.makecon(TypeInt::ZERO);
1226
1227 for (uint i = 1; i < n_ctrl->req(); i++) {
1228 if (is_dominator(proj_true, n_ctrl->in(i))) {
1229 bolphi->init_req(i, con_true);
1230 } else {
1231 assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1232 bolphi->init_req(i, con_false);
1233 }
1234 }
1235 register_new_node(bolphi, n_ctrl);
1236 _igvn.replace_input_of(n, 1, bolphi);
1237
1238 // Now split the IF
1239 do_split_if(n);
1240 return;
1241 }
1242
1243 // Check for an IF ready to split; one that has its
1244 // condition codes input coming from a Phi at the block start.
1245 int n_op = n->Opcode();
1246
1247 // Check for an IF being dominated by another IF same test
1248 if (n_op == Op_If ||
1249 n_op == Op_RangeCheck) {
1250 Node *bol = n->in(1);
1251 uint max = bol->outcnt();
1252 // Check for same test used more than once?
1253 if (max > 1 && bol->is_Bool()) {
1254 // Search up IDOMs to see if this IF is dominated.
1255 Node *cutoff = get_ctrl(bol);
1256
1257 // Now search up IDOMs till cutoff, looking for a dominating test
1258 Node *prevdom = n;
1259 Node *dom = idom(prevdom);
1260 while (dom != cutoff) {
1261 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1262 // Replace the dominated test with an obvious true or false.
1263 // Place it on the IGVN worklist for later cleanup.
1264 C->set_major_progress();
1265 dominated_by(prevdom, n, false, true);
1266 #ifndef PRODUCT
1267 if( VerifyLoopOptimizations ) verify();
1268 #endif
1269 return;
1270 }
1271 prevdom = dom;
1272 dom = idom(prevdom);
1273 }
1274 }
1275 }
1276
1277 // See if a shared loop-varying computation has no loop-varying uses.
1278 // Happens if something is only used for JVM state in uncommon trap exits,
1279 // like various versions of induction variable+offset. Clone the
1280 // computation per usage to allow it to sink out of the loop.
1281 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1282 Node *n_ctrl = get_ctrl(n);
1283 IdealLoopTree *n_loop = get_loop(n_ctrl);
1284 if( n_loop != _ltree_root ) {
1285 DUIterator_Fast imax, i = n->fast_outs(imax);
1286 for (; i < imax; i++) {
1287 Node* u = n->fast_out(i);
1288 if( !has_ctrl(u) ) break; // Found control user
1289 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1290 if( u_loop == n_loop ) break; // Found loop-varying use
1291 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1292 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1293 }
1294 bool did_break = (i < imax); // Did we break out of the previous loop?
1295 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1296 Node *late_load_ctrl = NULL;
1297 if (n->is_Load()) {
1298 // If n is a load, get and save the result from get_late_ctrl(),
1299 // to be later used in calculating the control for n's clones.
1300 clear_dom_lca_tags();
1301 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1302 }
1303 // If n is a load, and the late control is the same as the current
1304 // control, then the cloning of n is a pointless exercise, because
1305 // GVN will ensure that we end up where we started.
1306 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1307 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1308 Node *u = n->last_out(j); // Clone private computation per use
1309 _igvn.rehash_node_delayed(u);
1310 Node *x = n->clone(); // Clone computation
1311 Node *x_ctrl = NULL;
1312 if( u->is_Phi() ) {
1313 // Replace all uses of normal nodes. Replace Phi uses
1314 // individually, so the separate Nodes can sink down
1315 // different paths.
1316 uint k = 1;
1317 while( u->in(k) != n ) k++;
1318 u->set_req( k, x );
1319 // x goes next to Phi input path
1320 x_ctrl = u->in(0)->in(k);
1321 --j;
1322 } else { // Normal use
1323 // Replace all uses
1324 for( uint k = 0; k < u->req(); k++ ) {
1325 if( u->in(k) == n ) {
1326 u->set_req( k, x );
1327 --j;
1328 }
1329 }
1330 x_ctrl = get_ctrl(u);
1331 }
1332
1333 // Find control for 'x' next to use but not inside inner loops.
1334 // For inner loop uses get the preheader area.
1335 x_ctrl = place_near_use(x_ctrl);
1336
1337 if (n->is_Load()) {
1338 // For loads, add a control edge to a CFG node outside of the loop
1339 // to force them to not combine and return back inside the loop
1340 // during GVN optimization (4641526).
1341 //
1342 // Because we are setting the actual control input, factor in
1343 // the result from get_late_ctrl() so we respect any
1344 // anti-dependences. (6233005).
1345 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1346
1347 // Don't allow the control input to be a CFG splitting node.
1348 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1349 // should only have IfTrueNode and IfFalseNode (4985384).
1350 x_ctrl = find_non_split_ctrl(x_ctrl);
1351 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1352
1353 x->set_req(0, x_ctrl);
1354 }
1355 register_new_node(x, x_ctrl);
1356
1357 // Some institutional knowledge is needed here: 'x' is
1358 // yanked because if the optimizer runs GVN on it all the
1359 // cloned x's will common up and undo this optimization and
1360 // be forced back in the loop. This is annoying because it
1361 // makes +VerifyOpto report false-positives on progress. I
1362 // tried setting control edges on the x's to force them to
1363 // not combine, but the matching gets worried when it tries
1364 // to fold a StoreP and an AddP together (as part of an
1365 // address expression) and the AddP and StoreP have
1366 // different controls.
1367 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1368 }
1369 _igvn.remove_dead_node(n);
1370 }
1371 }
1372 }
1373 }
1374
1375 try_move_store_after_loop(n);
1376
1377 // Check for Opaque2's who's loop has disappeared - who's input is in the
1378 // same loop nest as their output. Remove 'em, they are no longer useful.
1379 if( n_op == Op_Opaque2 &&
1380 n->in(1) != NULL &&
1381 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1382 _igvn.replace_node( n, n->in(1) );
1383 }
1384
1385 #if INCLUDE_ZGC
1386 if (UseZGC) {
1387 ZBarrierSetC2::loop_optimize_gc_barrier(this, n, last_round);
1388 }
1389 #endif
1390 }
1391
1392 //------------------------------split_if_with_blocks---------------------------
1393 // Check for aggressive application of 'split-if' optimization,
1394 // using basic block level info.
1395 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack, bool last_round) {
1396 Node *n = C->root();
1397 visited.set(n->_idx); // first, mark node as visited
1398 // Do pre-visit work for root
1399 n = split_if_with_blocks_pre( n );
1400 uint cnt = n->outcnt();
1401 uint i = 0;
1402 while (true) {
1403 // Visit all children
1404 if (i < cnt) {
1405 Node* use = n->raw_out(i);
1406 ++i;
1407 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1408 // Now do pre-visit work for this use
1409 use = split_if_with_blocks_pre( use );
1410 nstack.push(n, i); // Save parent and next use's index.
1411 n = use; // Process all children of current use.
1412 cnt = use->outcnt();
1413 i = 0;
1414 }
1415 }
1416 else {
1417 // All of n's children have been processed, complete post-processing.
1418 if (cnt != 0 && !n->is_Con()) {
1419 assert(has_node(n), "no dead nodes");
1420 split_if_with_blocks_post( n, last_round );
1421 }
1422 if (nstack.is_empty()) {
1423 // Finished all nodes on stack.
1424 break;
1425 }
1426 // Get saved parent node and next use's index. Visit the rest of uses.
1427 n = nstack.node();
1428 cnt = n->outcnt();
1429 i = nstack.index();
1430 nstack.pop();
1431 }
1432 }
1433 }
1434
1435
1436 //=============================================================================
1437 //
1438 // C L O N E A L O O P B O D Y
1439 //
1440
1441 //------------------------------clone_iff--------------------------------------
1442 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1443 // "Nearly" because all Nodes have been cloned from the original in the loop,
1444 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1445 // through the Phi recursively, and return a Bool.
1446 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1447
1448 // Convert this Phi into a Phi merging Bools
1449 uint i;
1450 for (i = 1; i < phi->req(); i++) {
1451 Node *b = phi->in(i);
1452 if (b->is_Phi()) {
1453 _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1454 } else {
1455 assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1456 }
1457 }
1458
1459 Node* n = phi->in(1);
1460 Node* sample_opaque = NULL;
1461 Node *sample_bool = NULL;
1462 if (n->Opcode() == Op_Opaque4) {
1463 sample_opaque = n;
1464 sample_bool = n->in(1);
1465 assert(sample_bool->is_Bool(), "wrong type");
1466 } else {
1467 sample_bool = n;
1468 }
1469 Node *sample_cmp = sample_bool->in(1);
1470
1471 // Make Phis to merge the Cmp's inputs.
1472 PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1473 PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1474 for (i = 1; i < phi->req(); i++) {
1475 Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1476 Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1477 phi1->set_req(i, n1);
1478 phi2->set_req(i, n2);
1479 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1480 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1481 }
1482 // See if these Phis have been made before.
1483 // Register with optimizer
1484 Node *hit1 = _igvn.hash_find_insert(phi1);
1485 if (hit1) { // Hit, toss just made Phi
1486 _igvn.remove_dead_node(phi1); // Remove new phi
1487 assert(hit1->is_Phi(), "" );
1488 phi1 = (PhiNode*)hit1; // Use existing phi
1489 } else { // Miss
1490 _igvn.register_new_node_with_optimizer(phi1);
1491 }
1492 Node *hit2 = _igvn.hash_find_insert(phi2);
1493 if (hit2) { // Hit, toss just made Phi
1494 _igvn.remove_dead_node(phi2); // Remove new phi
1495 assert(hit2->is_Phi(), "" );
1496 phi2 = (PhiNode*)hit2; // Use existing phi
1497 } else { // Miss
1498 _igvn.register_new_node_with_optimizer(phi2);
1499 }
1500 // Register Phis with loop/block info
1501 set_ctrl(phi1, phi->in(0));
1502 set_ctrl(phi2, phi->in(0));
1503 // Make a new Cmp
1504 Node *cmp = sample_cmp->clone();
1505 cmp->set_req(1, phi1);
1506 cmp->set_req(2, phi2);
1507 _igvn.register_new_node_with_optimizer(cmp);
1508 set_ctrl(cmp, phi->in(0));
1509
1510 // Make a new Bool
1511 Node *b = sample_bool->clone();
1512 b->set_req(1,cmp);
1513 _igvn.register_new_node_with_optimizer(b);
1514 set_ctrl(b, phi->in(0));
1515
1516 if (sample_opaque != NULL) {
1517 Node* opaque = sample_opaque->clone();
1518 opaque->set_req(1, b);
1519 _igvn.register_new_node_with_optimizer(opaque);
1520 set_ctrl(opaque, phi->in(0));
1521 return opaque;
1522 }
1523
1524 assert(b->is_Bool(), "");
1525 return b;
1526 }
1527
1528 //------------------------------clone_bool-------------------------------------
1529 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1530 // "Nearly" because all Nodes have been cloned from the original in the loop,
1531 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1532 // through the Phi recursively, and return a Bool.
1533 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1534 uint i;
1535 // Convert this Phi into a Phi merging Bools
1536 for( i = 1; i < phi->req(); i++ ) {
1537 Node *b = phi->in(i);
1538 if( b->is_Phi() ) {
1539 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1540 } else {
1541 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1542 }
1543 }
1544
1545 Node *sample_cmp = phi->in(1);
1546
1547 // Make Phis to merge the Cmp's inputs.
1548 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1549 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1550 for( uint j = 1; j < phi->req(); j++ ) {
1551 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1552 Node *n1, *n2;
1553 if( cmp_top->is_Cmp() ) {
1554 n1 = cmp_top->in(1);
1555 n2 = cmp_top->in(2);
1556 } else {
1557 n1 = n2 = cmp_top;
1558 }
1559 phi1->set_req( j, n1 );
1560 phi2->set_req( j, n2 );
1561 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1562 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1563 }
1564
1565 // See if these Phis have been made before.
1566 // Register with optimizer
1567 Node *hit1 = _igvn.hash_find_insert(phi1);
1568 if( hit1 ) { // Hit, toss just made Phi
1569 _igvn.remove_dead_node(phi1); // Remove new phi
1570 assert( hit1->is_Phi(), "" );
1571 phi1 = (PhiNode*)hit1; // Use existing phi
1572 } else { // Miss
1573 _igvn.register_new_node_with_optimizer(phi1);
1574 }
1575 Node *hit2 = _igvn.hash_find_insert(phi2);
1576 if( hit2 ) { // Hit, toss just made Phi
1577 _igvn.remove_dead_node(phi2); // Remove new phi
1578 assert( hit2->is_Phi(), "" );
1579 phi2 = (PhiNode*)hit2; // Use existing phi
1580 } else { // Miss
1581 _igvn.register_new_node_with_optimizer(phi2);
1582 }
1583 // Register Phis with loop/block info
1584 set_ctrl(phi1, phi->in(0));
1585 set_ctrl(phi2, phi->in(0));
1586 // Make a new Cmp
1587 Node *cmp = sample_cmp->clone();
1588 cmp->set_req( 1, phi1 );
1589 cmp->set_req( 2, phi2 );
1590 _igvn.register_new_node_with_optimizer(cmp);
1591 set_ctrl(cmp, phi->in(0));
1592
1593 assert( cmp->is_Cmp(), "" );
1594 return (CmpNode*)cmp;
1595 }
1596
1597 //------------------------------sink_use---------------------------------------
1598 // If 'use' was in the loop-exit block, it now needs to be sunk
1599 // below the post-loop merge point.
1600 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1601 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1602 set_ctrl(use, post_loop);
1603 for (DUIterator j = use->outs(); use->has_out(j); j++)
1604 sink_use(use->out(j), post_loop);
1605 }
1606 }
1607
1608 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1609 IdealLoopTree* loop, IdealLoopTree* outer_loop,
1610 Node_List*& split_if_set, Node_List*& split_bool_set,
1611 Node_List*& split_cex_set, Node_List& worklist,
1612 uint new_counter, CloneLoopMode mode) {
1613 Node* nnn = old_new[old->_idx];
1614 // Copy uses to a worklist, so I can munge the def-use info
1615 // with impunity.
1616 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1617 worklist.push(old->fast_out(j));
1618
1619 while( worklist.size() ) {
1620 Node *use = worklist.pop();
1621 if (!has_node(use)) continue; // Ignore dead nodes
1622 if (use->in(0) == C->top()) continue;
1623 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1624 // Check for data-use outside of loop - at least one of OLD or USE
1625 // must not be a CFG node.
1626 #ifdef ASSERT
1627 if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1628 Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1629 assert(mode == ControlAroundStripMined && use == sfpt, "missed a node");
1630 }
1631 #endif
1632 if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1633
1634 // If the Data use is an IF, that means we have an IF outside of the
1635 // loop that is switching on a condition that is set inside of the
1636 // loop. Happens if people set a loop-exit flag; then test the flag
1637 // in the loop to break the loop, then test is again outside of the
1638 // loop to determine which way the loop exited.
1639 // Loop predicate If node connects to Bool node through Opaque1 node.
1640 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1641 // Since this code is highly unlikely, we lazily build the worklist
1642 // of such Nodes to go split.
1643 if (!split_if_set) {
1644 ResourceArea *area = Thread::current()->resource_area();
1645 split_if_set = new Node_List(area);
1646 }
1647 split_if_set->push(use);
1648 }
1649 if (use->is_Bool()) {
1650 if (!split_bool_set) {
1651 ResourceArea *area = Thread::current()->resource_area();
1652 split_bool_set = new Node_List(area);
1653 }
1654 split_bool_set->push(use);
1655 }
1656 if (use->Opcode() == Op_CreateEx) {
1657 if (!split_cex_set) {
1658 ResourceArea *area = Thread::current()->resource_area();
1659 split_cex_set = new Node_List(area);
1660 }
1661 split_cex_set->push(use);
1662 }
1663
1664
1665 // Get "block" use is in
1666 uint idx = 0;
1667 while( use->in(idx) != old ) idx++;
1668 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1669 assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1670 Node *cfg = prev->_idx >= new_counter
1671 ? prev->in(2)
1672 : idom(prev);
1673 if( use->is_Phi() ) // Phi use is in prior block
1674 cfg = prev->in(idx); // NOT in block of Phi itself
1675 if (cfg->is_top()) { // Use is dead?
1676 _igvn.replace_input_of(use, idx, C->top());
1677 continue;
1678 }
1679
1680 // If use is referenced through control edge... (idx == 0)
1681 if (mode == IgnoreStripMined && idx == 0) {
1682 LoopNode *head = loop->_head->as_Loop();
1683 if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1684 // That node is outside the inner loop, leave it outside the
1685 // outer loop as well to not confuse verification code.
1686 assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1687 _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1688 continue;
1689 }
1690 }
1691
1692 while(!outer_loop->is_member(get_loop(cfg))) {
1693 prev = cfg;
1694 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1695 }
1696 // If the use occurs after merging several exits from the loop, then
1697 // old value must have dominated all those exits. Since the same old
1698 // value was used on all those exits we did not need a Phi at this
1699 // merge point. NOW we do need a Phi here. Each loop exit value
1700 // is now merged with the peeled body exit; each exit gets its own
1701 // private Phi and those Phis need to be merged here.
1702 Node *phi;
1703 if( prev->is_Region() ) {
1704 if( idx == 0 ) { // Updating control edge?
1705 phi = prev; // Just use existing control
1706 } else { // Else need a new Phi
1707 phi = PhiNode::make( prev, old );
1708 // Now recursively fix up the new uses of old!
1709 for( uint i = 1; i < prev->req(); i++ ) {
1710 worklist.push(phi); // Onto worklist once for each 'old' input
1711 }
1712 }
1713 } else {
1714 // Get new RegionNode merging old and new loop exits
1715 prev = old_new[prev->_idx];
1716 assert( prev, "just made this in step 7" );
1717 if( idx == 0) { // Updating control edge?
1718 phi = prev; // Just use existing control
1719 } else { // Else need a new Phi
1720 // Make a new Phi merging data values properly
1721 phi = PhiNode::make( prev, old );
1722 phi->set_req( 1, nnn );
1723 }
1724 }
1725 // If inserting a new Phi, check for prior hits
1726 if( idx != 0 ) {
1727 Node *hit = _igvn.hash_find_insert(phi);
1728 if( hit == NULL ) {
1729 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1730 } else { // or
1731 // Remove the new phi from the graph and use the hit
1732 _igvn.remove_dead_node(phi);
1733 phi = hit; // Use existing phi
1734 }
1735 set_ctrl(phi, prev);
1736 }
1737 // Make 'use' use the Phi instead of the old loop body exit value
1738 _igvn.replace_input_of(use, idx, phi);
1739 if( use->_idx >= new_counter ) { // If updating new phis
1740 // Not needed for correctness, but prevents a weak assert
1741 // in AddPNode from tripping (when we end up with different
1742 // base & derived Phis that will become the same after
1743 // IGVN does CSE).
1744 Node *hit = _igvn.hash_find_insert(use);
1745 if( hit ) // Go ahead and re-hash for hits.
1746 _igvn.replace_node( use, hit );
1747 }
1748
1749 // If 'use' was in the loop-exit block, it now needs to be sunk
1750 // below the post-loop merge point.
1751 sink_use( use, prev );
1752 }
1753 }
1754 }
1755
1756 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1757 IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1758 Node_List& extra_data_nodes) {
1759 if (head->is_strip_mined() && mode != IgnoreStripMined) {
1760 CountedLoopNode* cl = head->as_CountedLoop();
1761 Node* l = cl->outer_loop();
1762 Node* tail = cl->outer_loop_tail();
1763 IfNode* le = cl->outer_loop_end();
1764 Node* sfpt = cl->outer_safepoint();
1765 CountedLoopEndNode* cle = cl->loopexit();
1766 CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1767 CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1768 Node* cle_out = cle->proj_out(false);
1769
1770 Node* new_sfpt = NULL;
1771 Node* new_cle_out = cle_out->clone();
1772 old_new.map(cle_out->_idx, new_cle_out);
1773 if (mode == CloneIncludesStripMined) {
1774 // clone outer loop body
1775 Node* new_l = l->clone();
1776 Node* new_tail = tail->clone();
1777 IfNode* new_le = le->clone()->as_If();
1778 new_sfpt = sfpt->clone();
1779
1780 set_loop(new_l, outer_loop->_parent);
1781 set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1782 set_loop(new_cle_out, outer_loop->_parent);
1783 set_idom(new_cle_out, new_cle, dd);
1784 set_loop(new_sfpt, outer_loop->_parent);
1785 set_idom(new_sfpt, new_cle_out, dd);
1786 set_loop(new_le, outer_loop->_parent);
1787 set_idom(new_le, new_sfpt, dd);
1788 set_loop(new_tail, outer_loop->_parent);
1789 set_idom(new_tail, new_le, dd);
1790 set_idom(new_cl, new_l, dd);
1791
1792 old_new.map(l->_idx, new_l);
1793 old_new.map(tail->_idx, new_tail);
1794 old_new.map(le->_idx, new_le);
1795 old_new.map(sfpt->_idx, new_sfpt);
1796
1797 new_l->set_req(LoopNode::LoopBackControl, new_tail);
1798 new_l->set_req(0, new_l);
1799 new_tail->set_req(0, new_le);
1800 new_le->set_req(0, new_sfpt);
1801 new_sfpt->set_req(0, new_cle_out);
1802 new_cle_out->set_req(0, new_cle);
1803 new_cl->set_req(LoopNode::EntryControl, new_l);
1804
1805 _igvn.register_new_node_with_optimizer(new_l);
1806 _igvn.register_new_node_with_optimizer(new_tail);
1807 _igvn.register_new_node_with_optimizer(new_le);
1808 } else {
1809 Node *newhead = old_new[loop->_head->_idx];
1810 newhead->as_Loop()->clear_strip_mined();
1811 _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
1812 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1813 }
1814 // Look at data node that were assigned a control in the outer
1815 // loop: they are kept in the outer loop by the safepoint so start
1816 // from the safepoint node's inputs.
1817 IdealLoopTree* outer_loop = get_loop(l);
1818 Node_Stack stack(2);
1819 stack.push(sfpt, 1);
1820 uint new_counter = C->unique();
1821 while (stack.size() > 0) {
1822 Node* n = stack.node();
1823 uint i = stack.index();
1824 while (i < n->req() &&
1825 (n->in(i) == NULL ||
1826 !has_ctrl(n->in(i)) ||
1827 get_loop(get_ctrl(n->in(i))) != outer_loop ||
1828 (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
1829 i++;
1830 }
1831 if (i < n->req()) {
1832 stack.set_index(i+1);
1833 stack.push(n->in(i), 0);
1834 } else {
1835 assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
1836 Node* m = n == sfpt ? new_sfpt : n->clone();
1837 if (m != NULL) {
1838 for (uint i = 0; i < n->req(); i++) {
1839 if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
1840 m->set_req(i, old_new[m->in(i)->_idx]);
1841 }
1842 }
1843 } else {
1844 assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
1845 }
1846 if (n != sfpt) {
1847 extra_data_nodes.push(n);
1848 _igvn.register_new_node_with_optimizer(m);
1849 assert(get_ctrl(n) == cle_out, "what other control?");
1850 set_ctrl(m, new_cle_out);
1851 old_new.map(n->_idx, m);
1852 }
1853 stack.pop();
1854 }
1855 }
1856 if (mode == CloneIncludesStripMined) {
1857 _igvn.register_new_node_with_optimizer(new_sfpt);
1858 _igvn.register_new_node_with_optimizer(new_cle_out);
1859 }
1860 } else {
1861 Node *newhead = old_new[loop->_head->_idx];
1862 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1863 }
1864 }
1865
1866 //------------------------------clone_loop-------------------------------------
1867 //
1868 // C L O N E A L O O P B O D Y
1869 //
1870 // This is the basic building block of the loop optimizations. It clones an
1871 // entire loop body. It makes an old_new loop body mapping; with this mapping
1872 // you can find the new-loop equivalent to an old-loop node. All new-loop
1873 // nodes are exactly equal to their old-loop counterparts, all edges are the
1874 // same. All exits from the old-loop now have a RegionNode that merges the
1875 // equivalent new-loop path. This is true even for the normal "loop-exit"
1876 // condition. All uses of loop-invariant old-loop values now come from (one
1877 // or more) Phis that merge their new-loop equivalents.
1878 //
1879 // This operation leaves the graph in an illegal state: there are two valid
1880 // control edges coming from the loop pre-header to both loop bodies. I'll
1881 // definitely have to hack the graph after running this transform.
1882 //
1883 // From this building block I will further edit edges to perform loop peeling
1884 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1885 //
1886 // Parameter side_by_size_idom:
1887 // When side_by_size_idom is NULL, the dominator tree is constructed for
1888 // the clone loop to dominate the original. Used in construction of
1889 // pre-main-post loop sequence.
1890 // When nonnull, the clone and original are side-by-side, both are
1891 // dominated by the side_by_side_idom node. Used in construction of
1892 // unswitched loops.
1893 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1894 CloneLoopMode mode, Node* side_by_side_idom) {
1895
1896 LoopNode* head = loop->_head->as_Loop();
1897 head->verify_strip_mined(1);
1898
1899 if (C->do_vector_loop() && PrintOpto) {
1900 const char* mname = C->method()->name()->as_quoted_ascii();
1901 if (mname != NULL) {
1902 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1903 }
1904 }
1905
1906 CloneMap& cm = C->clone_map();
1907 Dict* dict = cm.dict();
1908 if (C->do_vector_loop()) {
1909 cm.set_clone_idx(cm.max_gen()+1);
1910 #ifndef PRODUCT
1911 if (PrintOpto) {
1912 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1913 loop->dump_head();
1914 }
1915 #endif
1916 }
1917
1918 // Step 1: Clone the loop body. Make the old->new mapping.
1919 uint i;
1920 for( i = 0; i < loop->_body.size(); i++ ) {
1921 Node *old = loop->_body.at(i);
1922 Node *nnn = old->clone();
1923 old_new.map( old->_idx, nnn );
1924 if (C->do_vector_loop()) {
1925 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1926 }
1927 _igvn.register_new_node_with_optimizer(nnn);
1928 }
1929
1930 IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
1931
1932 // Step 2: Fix the edges in the new body. If the old input is outside the
1933 // loop use it. If the old input is INside the loop, use the corresponding
1934 // new node instead.
1935 for( i = 0; i < loop->_body.size(); i++ ) {
1936 Node *old = loop->_body.at(i);
1937 Node *nnn = old_new[old->_idx];
1938 // Fix CFG/Loop controlling the new node
1939 if (has_ctrl(old)) {
1940 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1941 } else {
1942 set_loop(nnn, outer_loop->_parent);
1943 if (old->outcnt() > 0) {
1944 set_idom( nnn, old_new[idom(old)->_idx], dd );
1945 }
1946 }
1947 // Correct edges to the new node
1948 for( uint j = 0; j < nnn->req(); j++ ) {
1949 Node *n = nnn->in(j);
1950 if( n ) {
1951 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1952 if( loop->is_member( old_in_loop ) )
1953 nnn->set_req(j, old_new[n->_idx]);
1954 }
1955 }
1956 _igvn.hash_find_insert(nnn);
1957 }
1958
1959 ResourceArea *area = Thread::current()->resource_area();
1960 Node_List extra_data_nodes(area);
1961 clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
1962
1963 // Step 3: Now fix control uses. Loop varying control uses have already
1964 // been fixed up (as part of all input edges in Step 2). Loop invariant
1965 // control uses must be either an IfFalse or an IfTrue. Make a merge
1966 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1967 // refer to this.
1968 Node_List worklist(area);
1969 uint new_counter = C->unique();
1970 for( i = 0; i < loop->_body.size(); i++ ) {
1971 Node* old = loop->_body.at(i);
1972 if( !old->is_CFG() ) continue;
1973
1974 // Copy uses to a worklist, so I can munge the def-use info
1975 // with impunity.
1976 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1977 worklist.push(old->fast_out(j));
1978
1979 while( worklist.size() ) { // Visit all uses
1980 Node *use = worklist.pop();
1981 if (!has_node(use)) continue; // Ignore dead nodes
1982 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1983 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1984 // Both OLD and USE are CFG nodes here.
1985 assert( use->is_Proj(), "" );
1986 Node* nnn = old_new[old->_idx];
1987
1988 Node* newuse = NULL;
1989 if (head->is_strip_mined() && mode != IgnoreStripMined) {
1990 CountedLoopNode* cl = head->as_CountedLoop();
1991 CountedLoopEndNode* cle = cl->loopexit();
1992 Node* cle_out = cle->proj_out_or_null(false);
1993 if (use == cle_out) {
1994 IfNode* le = cl->outer_loop_end();
1995 use = le->proj_out(false);
1996 use_loop = get_loop(use);
1997 if (mode == CloneIncludesStripMined) {
1998 nnn = old_new[le->_idx];
1999 } else {
2000 newuse = old_new[cle_out->_idx];
2001 }
2002 }
2003 }
2004 if (newuse == NULL) {
2005 newuse = use->clone();
2006 }
2007
2008 // Clone the loop exit control projection
2009 if (C->do_vector_loop()) {
2010 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2011 }
2012 newuse->set_req(0,nnn);
2013 _igvn.register_new_node_with_optimizer(newuse);
2014 set_loop(newuse, use_loop);
2015 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2016
2017 // We need a Region to merge the exit from the peeled body and the
2018 // exit from the old loop body.
2019 RegionNode *r = new RegionNode(3);
2020 // Map the old use to the new merge point
2021 old_new.map( use->_idx, r );
2022 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2023 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2024
2025 // The original user of 'use' uses 'r' instead.
2026 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2027 Node* useuse = use->last_out(l);
2028 _igvn.rehash_node_delayed(useuse);
2029 uint uses_found = 0;
2030 if( useuse->in(0) == use ) {
2031 useuse->set_req(0, r);
2032 uses_found++;
2033 if( useuse->is_CFG() ) {
2034 assert( dom_depth(useuse) > dd_r, "" );
2035 set_idom(useuse, r, dom_depth(useuse));
2036 }
2037 }
2038 for( uint k = 1; k < useuse->req(); k++ ) {
2039 if( useuse->in(k) == use ) {
2040 useuse->set_req(k, r);
2041 uses_found++;
2042 if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2043 assert(dom_depth(useuse) > dd_r , "");
2044 set_idom(useuse, r, dom_depth(useuse));
2045 }
2046 }
2047 }
2048 l -= uses_found; // we deleted 1 or more copies of this edge
2049 }
2050
2051 // Now finish up 'r'
2052 r->set_req( 1, newuse );
2053 r->set_req( 2, use );
2054 _igvn.register_new_node_with_optimizer(r);
2055 set_loop(r, use_loop);
2056 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2057 } // End of if a loop-exit test
2058 }
2059 }
2060
2061 // Step 4: If loop-invariant use is not control, it must be dominated by a
2062 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
2063 // there if needed. Make a Phi there merging old and new used values.
2064 Node_List *split_if_set = NULL;
2065 Node_List *split_bool_set = NULL;
2066 Node_List *split_cex_set = NULL;
2067 for( i = 0; i < loop->_body.size(); i++ ) {
2068 Node* old = loop->_body.at(i);
2069 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2070 split_bool_set, split_cex_set, worklist, new_counter,
2071 mode);
2072 }
2073
2074 for (i = 0; i < extra_data_nodes.size(); i++) {
2075 Node* old = extra_data_nodes.at(i);
2076 clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2077 split_bool_set, split_cex_set, worklist, new_counter,
2078 mode);
2079 }
2080
2081 // Check for IFs that need splitting/cloning. Happens if an IF outside of
2082 // the loop uses a condition set in the loop. The original IF probably
2083 // takes control from one or more OLD Regions (which in turn get from NEW
2084 // Regions). In any case, there will be a set of Phis for each merge point
2085 // from the IF up to where the original BOOL def exists the loop.
2086 if (split_if_set) {
2087 while (split_if_set->size()) {
2088 Node *iff = split_if_set->pop();
2089 if (iff->in(1)->is_Phi()) {
2090 Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2091 _igvn.replace_input_of(iff, 1, b);
2092 }
2093 }
2094 }
2095 if (split_bool_set) {
2096 while (split_bool_set->size()) {
2097 Node *b = split_bool_set->pop();
2098 Node *phi = b->in(1);
2099 assert(phi->is_Phi(), "");
2100 CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2101 _igvn.replace_input_of(b, 1, cmp);
2102 }
2103 }
2104 if (split_cex_set) {
2105 while (split_cex_set->size()) {
2106 Node *b = split_cex_set->pop();
2107 assert(b->in(0)->is_Region(), "");
2108 assert(b->in(1)->is_Phi(), "");
2109 assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2110 split_up(b, b->in(0), NULL);
2111 }
2112 }
2113
2114 }
2115
2116
2117 //---------------------- stride_of_possible_iv -------------------------------------
2118 // Looks for an iff/bool/comp with one operand of the compare
2119 // being a cycle involving an add and a phi,
2120 // with an optional truncation (left-shift followed by a right-shift)
2121 // of the add. Returns zero if not an iv.
2122 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2123 Node* trunc1 = NULL;
2124 Node* trunc2 = NULL;
2125 const TypeInt* ttype = NULL;
2126 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2127 return 0;
2128 }
2129 BoolNode* bl = iff->in(1)->as_Bool();
2130 Node* cmp = bl->in(1);
2131 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2132 return 0;
2133 }
2134 // Must have an invariant operand
2135 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2136 return 0;
2137 }
2138 Node* add2 = NULL;
2139 Node* cmp1 = cmp->in(1);
2140 if (cmp1->is_Phi()) {
2141 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2142 Node* phi = cmp1;
2143 for (uint i = 1; i < phi->req(); i++) {
2144 Node* in = phi->in(i);
2145 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2146 &trunc1, &trunc2, &ttype);
2147 if (add && add->in(1) == phi) {
2148 add2 = add->in(2);
2149 break;
2150 }
2151 }
2152 } else {
2153 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2154 Node* addtrunc = cmp1;
2155 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2156 &trunc1, &trunc2, &ttype);
2157 if (add && add->in(1)->is_Phi()) {
2158 Node* phi = add->in(1);
2159 for (uint i = 1; i < phi->req(); i++) {
2160 if (phi->in(i) == addtrunc) {
2161 add2 = add->in(2);
2162 break;
2163 }
2164 }
2165 }
2166 }
2167 if (add2 != NULL) {
2168 const TypeInt* add2t = _igvn.type(add2)->is_int();
2169 if (add2t->is_con()) {
2170 return add2t->get_con();
2171 }
2172 }
2173 return 0;
2174 }
2175
2176
2177 //---------------------- stay_in_loop -------------------------------------
2178 // Return the (unique) control output node that's in the loop (if it exists.)
2179 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2180 Node* unique = NULL;
2181 if (!n) return NULL;
2182 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2183 Node* use = n->fast_out(i);
2184 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2185 if (unique != NULL) {
2186 return NULL;
2187 }
2188 unique = use;
2189 }
2190 }
2191 return unique;
2192 }
2193
2194 //------------------------------ register_node -------------------------------------
2195 // Utility to register node "n" with PhaseIdealLoop
2196 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2197 _igvn.register_new_node_with_optimizer(n);
2198 loop->_body.push(n);
2199 if (n->is_CFG()) {
2200 set_loop(n, loop);
2201 set_idom(n, pred, ddepth);
2202 } else {
2203 set_ctrl(n, pred);
2204 }
2205 }
2206
2207 //------------------------------ proj_clone -------------------------------------
2208 // Utility to create an if-projection
2209 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2210 ProjNode* c = p->clone()->as_Proj();
2211 c->set_req(0, iff);
2212 return c;
2213 }
2214
2215 //------------------------------ short_circuit_if -------------------------------------
2216 // Force the iff control output to be the live_proj
2217 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2218 guarantee(live_proj != NULL, "null projection");
2219 int proj_con = live_proj->_con;
2220 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2221 Node *con = _igvn.intcon(proj_con);
2222 set_ctrl(con, C->root());
2223 if (iff) {
2224 iff->set_req(1, con);
2225 }
2226 return con;
2227 }
2228
2229 //------------------------------ insert_if_before_proj -------------------------------------
2230 // Insert a new if before an if projection (* - new node)
2231 //
2232 // before
2233 // if(test)
2234 // / \
2235 // v v
2236 // other-proj proj (arg)
2237 //
2238 // after
2239 // if(test)
2240 // / \
2241 // / v
2242 // | * proj-clone
2243 // v |
2244 // other-proj v
2245 // * new_if(relop(cmp[IU](left,right)))
2246 // / \
2247 // v v
2248 // * new-proj proj
2249 // (returned)
2250 //
2251 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2252 IfNode* iff = proj->in(0)->as_If();
2253 IdealLoopTree *loop = get_loop(proj);
2254 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2255 int ddepth = dom_depth(proj);
2256
2257 _igvn.rehash_node_delayed(iff);
2258 _igvn.rehash_node_delayed(proj);
2259
2260 proj->set_req(0, NULL); // temporary disconnect
2261 ProjNode* proj2 = proj_clone(proj, iff);
2262 register_node(proj2, loop, iff, ddepth);
2263
2264 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2265 register_node(cmp, loop, proj2, ddepth);
2266
2267 BoolNode* bol = new BoolNode(cmp, relop);
2268 register_node(bol, loop, proj2, ddepth);
2269
2270 int opcode = iff->Opcode();
2271 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2272 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2273 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2274 register_node(new_if, loop, proj2, ddepth);
2275
2276 proj->set_req(0, new_if); // reattach
2277 set_idom(proj, new_if, ddepth);
2278
2279 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2280 guarantee(new_exit != NULL, "null exit node");
2281 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2282
2283 return new_exit;
2284 }
2285
2286 //------------------------------ insert_region_before_proj -------------------------------------
2287 // Insert a region before an if projection (* - new node)
2288 //
2289 // before
2290 // if(test)
2291 // / |
2292 // v |
2293 // proj v
2294 // other-proj
2295 //
2296 // after
2297 // if(test)
2298 // / |
2299 // v |
2300 // * proj-clone v
2301 // | other-proj
2302 // v
2303 // * new-region
2304 // |
2305 // v
2306 // * dum_if
2307 // / \
2308 // v \
2309 // * dum-proj v
2310 // proj
2311 //
2312 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2313 IfNode* iff = proj->in(0)->as_If();
2314 IdealLoopTree *loop = get_loop(proj);
2315 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2316 int ddepth = dom_depth(proj);
2317
2318 _igvn.rehash_node_delayed(iff);
2319 _igvn.rehash_node_delayed(proj);
2320
2321 proj->set_req(0, NULL); // temporary disconnect
2322 ProjNode* proj2 = proj_clone(proj, iff);
2323 register_node(proj2, loop, iff, ddepth);
2324
2325 RegionNode* reg = new RegionNode(2);
2326 reg->set_req(1, proj2);
2327 register_node(reg, loop, iff, ddepth);
2328
2329 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2330 register_node(dum_if, loop, reg, ddepth);
2331
2332 proj->set_req(0, dum_if); // reattach
2333 set_idom(proj, dum_if, ddepth);
2334
2335 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2336 register_node(dum_proj, loop, dum_if, ddepth);
2337
2338 return reg;
2339 }
2340
2341 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2342 // Clone a signed compare loop exit from an unsigned compare and
2343 // insert it before the unsigned cmp on the stay-in-loop path.
2344 // All new nodes inserted in the dominator tree between the original
2345 // if and it's projections. The original if test is replaced with
2346 // a constant to force the stay-in-loop path.
2347 //
2348 // This is done to make sure that the original if and it's projections
2349 // still dominate the same set of control nodes, that the ctrl() relation
2350 // from data nodes to them is preserved, and that their loop nesting is
2351 // preserved.
2352 //
2353 // before
2354 // if(i <u limit) unsigned compare loop exit
2355 // / |
2356 // v v
2357 // exit-proj stay-in-loop-proj
2358 //
2359 // after
2360 // if(stay-in-loop-const) original if
2361 // / |
2362 // / v
2363 // / if(i < limit) new signed test
2364 // / / |
2365 // / / v
2366 // / / if(i <u limit) new cloned unsigned test
2367 // / / / |
2368 // v v v |
2369 // region |
2370 // | |
2371 // dum-if |
2372 // / | |
2373 // ether | |
2374 // v v
2375 // exit-proj stay-in-loop-proj
2376 //
2377 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2378 const bool Signed = true;
2379 const bool Unsigned = false;
2380
2381 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2382 if (bol->_test._test != BoolTest::lt) return NULL;
2383 CmpNode* cmpu = bol->in(1)->as_Cmp();
2384 if (cmpu->Opcode() != Op_CmpU) return NULL;
2385 int stride = stride_of_possible_iv(if_cmpu);
2386 if (stride == 0) return NULL;
2387
2388 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2389 guarantee(lp_proj != NULL, "null loop node");
2390
2391 ProjNode* lp_continue = lp_proj->as_Proj();
2392 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2393
2394 Node* limit = NULL;
2395 if (stride > 0) {
2396 limit = cmpu->in(2);
2397 } else {
2398 limit = _igvn.makecon(TypeInt::ZERO);
2399 set_ctrl(limit, C->root());
2400 }
2401 // Create a new region on the exit path
2402 RegionNode* reg = insert_region_before_proj(lp_exit);
2403 guarantee(reg != NULL, "null region node");
2404
2405 // Clone the if-cmpu-true-false using a signed compare
2406 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2407 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2408 reg->add_req(cmpi_exit);
2409
2410 // Clone the if-cmpu-true-false
2411 BoolTest::mask rel_u = bol->_test._test;
2412 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2413 reg->add_req(cmpu_exit);
2414
2415 // Force original if to stay in loop.
2416 short_circuit_if(if_cmpu, lp_continue);
2417
2418 return cmpi_exit->in(0)->as_If();
2419 }
2420
2421 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2422 // Remove a previously inserted signed compare loop exit.
2423 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2424 Node* lp_proj = stay_in_loop(if_cmp, loop);
2425 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2426 stay_in_loop(lp_proj, loop)->is_If() &&
2427 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2428 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2429 set_ctrl(con, C->root());
2430 if_cmp->set_req(1, con);
2431 }
2432
2433 //------------------------------ scheduled_nodelist -------------------------------------
2434 // Create a post order schedule of nodes that are in the
2435 // "member" set. The list is returned in "sched".
2436 // The first node in "sched" is the loop head, followed by
2437 // nodes which have no inputs in the "member" set, and then
2438 // followed by the nodes that have an immediate input dependence
2439 // on a node in "sched".
2440 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2441
2442 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2443 Arena *a = Thread::current()->resource_area();
2444 VectorSet visited(a);
2445 Node_Stack nstack(a, loop->_body.size());
2446
2447 Node* n = loop->_head; // top of stack is cached in "n"
2448 uint idx = 0;
2449 visited.set(n->_idx);
2450
2451 // Initially push all with no inputs from within member set
2452 for(uint i = 0; i < loop->_body.size(); i++ ) {
2453 Node *elt = loop->_body.at(i);
2454 if (member.test(elt->_idx)) {
2455 bool found = false;
2456 for (uint j = 0; j < elt->req(); j++) {
2457 Node* def = elt->in(j);
2458 if (def && member.test(def->_idx) && def != elt) {
2459 found = true;
2460 break;
2461 }
2462 }
2463 if (!found && elt != loop->_head) {
2464 nstack.push(n, idx);
2465 n = elt;
2466 assert(!visited.test(n->_idx), "not seen yet");
2467 visited.set(n->_idx);
2468 }
2469 }
2470 }
2471
2472 // traverse out's that are in the member set
2473 while (true) {
2474 if (idx < n->outcnt()) {
2475 Node* use = n->raw_out(idx);
2476 idx++;
2477 if (!visited.test_set(use->_idx)) {
2478 if (member.test(use->_idx)) {
2479 nstack.push(n, idx);
2480 n = use;
2481 idx = 0;
2482 }
2483 }
2484 } else {
2485 // All outputs processed
2486 sched.push(n);
2487 if (nstack.is_empty()) break;
2488 n = nstack.node();
2489 idx = nstack.index();
2490 nstack.pop();
2491 }
2492 }
2493 }
2494
2495
2496 //------------------------------ has_use_in_set -------------------------------------
2497 // Has a use in the vector set
2498 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2499 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2500 Node* use = n->fast_out(j);
2501 if (vset.test(use->_idx)) {
2502 return true;
2503 }
2504 }
2505 return false;
2506 }
2507
2508
2509 //------------------------------ has_use_internal_to_set -------------------------------------
2510 // Has use internal to the vector set (ie. not in a phi at the loop head)
2511 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2512 Node* head = loop->_head;
2513 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2514 Node* use = n->fast_out(j);
2515 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2516 return true;
2517 }
2518 }
2519 return false;
2520 }
2521
2522
2523 //------------------------------ clone_for_use_outside_loop -------------------------------------
2524 // clone "n" for uses that are outside of loop
2525 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2526 int cloned = 0;
2527 assert(worklist.size() == 0, "should be empty");
2528 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2529 Node* use = n->fast_out(j);
2530 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2531 worklist.push(use);
2532 }
2533 }
2534 while( worklist.size() ) {
2535 Node *use = worklist.pop();
2536 if (!has_node(use) || use->in(0) == C->top()) continue;
2537 uint j;
2538 for (j = 0; j < use->req(); j++) {
2539 if (use->in(j) == n) break;
2540 }
2541 assert(j < use->req(), "must be there");
2542
2543 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2544 Node* n_clone = n->clone();
2545 _igvn.replace_input_of(use, j, n_clone);
2546 cloned++;
2547 Node* use_c;
2548 if (!use->is_Phi()) {
2549 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2550 } else {
2551 // Use in a phi is considered a use in the associated predecessor block
2552 use_c = use->in(0)->in(j);
2553 }
2554 set_ctrl(n_clone, use_c);
2555 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2556 get_loop(use_c)->_body.push(n_clone);
2557 _igvn.register_new_node_with_optimizer(n_clone);
2558 #if !defined(PRODUCT)
2559 if (TracePartialPeeling) {
2560 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2561 }
2562 #endif
2563 }
2564 return cloned;
2565 }
2566
2567
2568 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2569 // clone "n" for special uses that are in the not_peeled region.
2570 // If these def-uses occur in separate blocks, the code generator
2571 // marks the method as not compilable. For example, if a "BoolNode"
2572 // is in a different basic block than the "IfNode" that uses it, then
2573 // the compilation is aborted in the code generator.
2574 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2575 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2576 if (n->is_Phi() || n->is_Load()) {
2577 return;
2578 }
2579 assert(worklist.size() == 0, "should be empty");
2580 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2581 Node* use = n->fast_out(j);
2582 if ( not_peel.test(use->_idx) &&
2583 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2584 use->in(1) == n) {
2585 worklist.push(use);
2586 }
2587 }
2588 if (worklist.size() > 0) {
2589 // clone "n" and insert it between inputs of "n" and the use
2590 Node* n_clone = n->clone();
2591 loop->_body.push(n_clone);
2592 _igvn.register_new_node_with_optimizer(n_clone);
2593 set_ctrl(n_clone, get_ctrl(n));
2594 sink_list.push(n_clone);
2595 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2596 #if !defined(PRODUCT)
2597 if (TracePartialPeeling) {
2598 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2599 }
2600 #endif
2601 while( worklist.size() ) {
2602 Node *use = worklist.pop();
2603 _igvn.rehash_node_delayed(use);
2604 for (uint j = 1; j < use->req(); j++) {
2605 if (use->in(j) == n) {
2606 use->set_req(j, n_clone);
2607 }
2608 }
2609 }
2610 }
2611 }
2612
2613
2614 //------------------------------ insert_phi_for_loop -------------------------------------
2615 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2616 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2617 Node *phi = PhiNode::make(lp, back_edge_val);
2618 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2619 // Use existing phi if it already exists
2620 Node *hit = _igvn.hash_find_insert(phi);
2621 if( hit == NULL ) {
2622 _igvn.register_new_node_with_optimizer(phi);
2623 set_ctrl(phi, lp);
2624 } else {
2625 // Remove the new phi from the graph and use the hit
2626 _igvn.remove_dead_node(phi);
2627 phi = hit;
2628 }
2629 _igvn.replace_input_of(use, idx, phi);
2630 }
2631
2632 #ifdef ASSERT
2633 //------------------------------ is_valid_loop_partition -------------------------------------
2634 // Validate the loop partition sets: peel and not_peel
2635 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2636 VectorSet& not_peel ) {
2637 uint i;
2638 // Check that peel_list entries are in the peel set
2639 for (i = 0; i < peel_list.size(); i++) {
2640 if (!peel.test(peel_list.at(i)->_idx)) {
2641 return false;
2642 }
2643 }
2644 // Check at loop members are in one of peel set or not_peel set
2645 for (i = 0; i < loop->_body.size(); i++ ) {
2646 Node *def = loop->_body.at(i);
2647 uint di = def->_idx;
2648 // Check that peel set elements are in peel_list
2649 if (peel.test(di)) {
2650 if (not_peel.test(di)) {
2651 return false;
2652 }
2653 // Must be in peel_list also
2654 bool found = false;
2655 for (uint j = 0; j < peel_list.size(); j++) {
2656 if (peel_list.at(j)->_idx == di) {
2657 found = true;
2658 break;
2659 }
2660 }
2661 if (!found) {
2662 return false;
2663 }
2664 } else if (not_peel.test(di)) {
2665 if (peel.test(di)) {
2666 return false;
2667 }
2668 } else {
2669 return false;
2670 }
2671 }
2672 return true;
2673 }
2674
2675 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2676 // Ensure a use outside of loop is of the right form
2677 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2678 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2679 return (use->is_Phi() &&
2680 use_c->is_Region() && use_c->req() == 3 &&
2681 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2682 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2683 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2684 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2685 }
2686
2687 //------------------------------ is_valid_clone_loop_form -------------------------------------
2688 // Ensure that all uses outside of loop are of the right form
2689 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2690 uint orig_exit_idx, uint clone_exit_idx) {
2691 uint len = peel_list.size();
2692 for (uint i = 0; i < len; i++) {
2693 Node *def = peel_list.at(i);
2694
2695 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2696 Node *use = def->fast_out(j);
2697 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2698 if (!loop->is_member(get_loop(use_c))) {
2699 // use is not in the loop, check for correct structure
2700 if (use->in(0) == def) {
2701 // Okay
2702 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2703 return false;
2704 }
2705 }
2706 }
2707 }
2708 return true;
2709 }
2710 #endif
2711
2712 //------------------------------ partial_peel -------------------------------------
2713 // Partially peel (aka loop rotation) the top portion of a loop (called
2714 // the peel section below) by cloning it and placing one copy just before
2715 // the new loop head and the other copy at the bottom of the new loop.
2716 //
2717 // before after where it came from
2718 //
2719 // stmt1 stmt1
2720 // loop: stmt2 clone
2721 // stmt2 if condA goto exitA clone
2722 // if condA goto exitA new_loop: new
2723 // stmt3 stmt3 clone
2724 // if !condB goto loop if condB goto exitB clone
2725 // exitB: stmt2 orig
2726 // stmt4 if !condA goto new_loop orig
2727 // exitA: goto exitA
2728 // exitB:
2729 // stmt4
2730 // exitA:
2731 //
2732 // Step 1: find the cut point: an exit test on probable
2733 // induction variable.
2734 // Step 2: schedule (with cloning) operations in the peel
2735 // section that can be executed after the cut into
2736 // the section that is not peeled. This may need
2737 // to clone operations into exit blocks. For
2738 // instance, a reference to A[i] in the not-peel
2739 // section and a reference to B[i] in an exit block
2740 // may cause a left-shift of i by 2 to be placed
2741 // in the peel block. This step will clone the left
2742 // shift into the exit block and sink the left shift
2743 // from the peel to the not-peel section.
2744 // Step 3: clone the loop, retarget the control, and insert
2745 // phis for values that are live across the new loop
2746 // head. This is very dependent on the graph structure
2747 // from clone_loop. It creates region nodes for
2748 // exit control and associated phi nodes for values
2749 // flow out of the loop through that exit. The region
2750 // node is dominated by the clone's control projection.
2751 // So the clone's peel section is placed before the
2752 // new loop head, and the clone's not-peel section is
2753 // forms the top part of the new loop. The original
2754 // peel section forms the tail of the new loop.
2755 // Step 4: update the dominator tree and recompute the
2756 // dominator depth.
2757 //
2758 // orig
2759 //
2760 // stmt1
2761 // |
2762 // v
2763 // loop predicate
2764 // |
2765 // v
2766 // loop<----+
2767 // | |
2768 // stmt2 |
2769 // | |
2770 // v |
2771 // ifA |
2772 // / | |
2773 // v v |
2774 // false true ^ <-- last_peel
2775 // / | |
2776 // / ===|==cut |
2777 // / stmt3 | <-- first_not_peel
2778 // / | |
2779 // | v |
2780 // v ifB |
2781 // exitA: / \ |
2782 // / \ |
2783 // v v |
2784 // false true |
2785 // / \ |
2786 // / ----+
2787 // |
2788 // v
2789 // exitB:
2790 // stmt4
2791 //
2792 //
2793 // after clone loop
2794 //
2795 // stmt1
2796 // |
2797 // v
2798 // loop predicate
2799 // / \
2800 // clone / \ orig
2801 // / \
2802 // / \
2803 // v v
2804 // +---->loop loop<----+
2805 // | | | |
2806 // | stmt2 stmt2 |
2807 // | | | |
2808 // | v v |
2809 // | ifA ifA |
2810 // | | \ / | |
2811 // | v v v v |
2812 // ^ true false false true ^ <-- last_peel
2813 // | | ^ \ / | |
2814 // | cut==|== \ \ / ===|==cut |
2815 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2816 // | | dom | | | |
2817 // | v \ 1v v2 v |
2818 // | ifB regionA ifB |
2819 // | / \ | / \ |
2820 // | / \ v / \ |
2821 // | v v exitA: v v |
2822 // | true false false true |
2823 // | / ^ \ / \ |
2824 // +---- \ \ / ----+
2825 // dom \ /
2826 // \ 1v v2
2827 // regionB
2828 // |
2829 // v
2830 // exitB:
2831 // stmt4
2832 //
2833 //
2834 // after partial peel
2835 //
2836 // stmt1
2837 // |
2838 // v
2839 // loop predicate
2840 // /
2841 // clone / orig
2842 // / TOP
2843 // / \
2844 // v v
2845 // TOP->loop loop----+
2846 // | | |
2847 // stmt2 stmt2 |
2848 // | | |
2849 // v v |
2850 // ifA ifA |
2851 // | \ / | |
2852 // v v v v |
2853 // true false false true | <-- last_peel
2854 // | ^ \ / +------|---+
2855 // +->newloop \ \ / === ==cut | |
2856 // | stmt3 \ \ / TOP | |
2857 // | | dom | | stmt3 | | <-- first_not_peel
2858 // | v \ 1v v2 v | |
2859 // | ifB regionA ifB ^ v
2860 // | / \ | / \ | |
2861 // | / \ v / \ | |
2862 // | v v exitA: v v | |
2863 // | true false false true | |
2864 // | / ^ \ / \ | |
2865 // | | \ \ / v | |
2866 // | | dom \ / TOP | |
2867 // | | \ 1v v2 | |
2868 // ^ v regionB | |
2869 // | | | | |
2870 // | | v ^ v
2871 // | | exitB: | |
2872 // | | stmt4 | |
2873 // | +------------>-----------------+ |
2874 // | |
2875 // +-----------------<---------------------+
2876 //
2877 //
2878 // final graph
2879 //
2880 // stmt1
2881 // |
2882 // v
2883 // loop predicate
2884 // |
2885 // v
2886 // stmt2 clone
2887 // |
2888 // v
2889 // ........> ifA clone
2890 // : / |
2891 // dom / |
2892 // : v v
2893 // : false true
2894 // : | |
2895 // : | v
2896 // : | newloop<-----+
2897 // : | | |
2898 // : | stmt3 clone |
2899 // : | | |
2900 // : | v |
2901 // : | ifB |
2902 // : | / \ |
2903 // : | v v |
2904 // : | false true |
2905 // : | | | |
2906 // : | v stmt2 |
2907 // : | exitB: | |
2908 // : | stmt4 v |
2909 // : | ifA orig |
2910 // : | / \ |
2911 // : | / \ |
2912 // : | v v |
2913 // : | false true |
2914 // : | / \ |
2915 // : v v -----+
2916 // RegionA
2917 // |
2918 // v
2919 // exitA
2920 //
2921 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2922
2923 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2924 if (!loop->_head->is_Loop()) {
2925 return false; }
2926
2927 LoopNode *head = loop->_head->as_Loop();
2928
2929 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2930 return false;
2931 }
2932
2933 // Check for complex exit control
2934 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2935 Node *n = loop->_body.at(ii);
2936 int opc = n->Opcode();
2937 if (n->is_Call() ||
2938 opc == Op_Catch ||
2939 opc == Op_CatchProj ||
2940 opc == Op_Jump ||
2941 opc == Op_JumpProj) {
2942 #if !defined(PRODUCT)
2943 if (TracePartialPeeling) {
2944 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2945 }
2946 #endif
2947 return false;
2948 }
2949 }
2950
2951 int dd = dom_depth(head);
2952
2953 // Step 1: find cut point
2954
2955 // Walk up dominators to loop head looking for first loop exit
2956 // which is executed on every path thru loop.
2957 IfNode *peel_if = NULL;
2958 IfNode *peel_if_cmpu = NULL;
2959
2960 Node *iff = loop->tail();
2961 while( iff != head ) {
2962 if( iff->is_If() ) {
2963 Node *ctrl = get_ctrl(iff->in(1));
2964 if (ctrl->is_top()) return false; // Dead test on live IF.
2965 // If loop-varying exit-test, check for induction variable
2966 if( loop->is_member(get_loop(ctrl)) &&
2967 loop->is_loop_exit(iff) &&
2968 is_possible_iv_test(iff)) {
2969 Node* cmp = iff->in(1)->in(1);
2970 if (cmp->Opcode() == Op_CmpI) {
2971 peel_if = iff->as_If();
2972 } else {
2973 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2974 peel_if_cmpu = iff->as_If();
2975 }
2976 }
2977 }
2978 iff = idom(iff);
2979 }
2980 // Prefer signed compare over unsigned compare.
2981 IfNode* new_peel_if = NULL;
2982 if (peel_if == NULL) {
2983 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2984 return false; // No peel point found
2985 }
2986 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2987 if (new_peel_if == NULL) {
2988 return false; // No peel point found
2989 }
2990 peel_if = new_peel_if;
2991 }
2992 Node* last_peel = stay_in_loop(peel_if, loop);
2993 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2994 if (first_not_peeled == NULL || first_not_peeled == head) {
2995 return false;
2996 }
2997
2998 #if !defined(PRODUCT)
2999 if (TraceLoopOpts) {
3000 tty->print("PartialPeel ");
3001 loop->dump_head();
3002 }
3003
3004 if (TracePartialPeeling) {
3005 tty->print_cr("before partial peel one iteration");
3006 Node_List wl;
3007 Node* t = head->in(2);
3008 while (true) {
3009 wl.push(t);
3010 if (t == head) break;
3011 t = idom(t);
3012 }
3013 while (wl.size() > 0) {
3014 Node* tt = wl.pop();
3015 tt->dump();
3016 if (tt == last_peel) tty->print_cr("-- cut --");
3017 }
3018 }
3019 #endif
3020 ResourceArea *area = Thread::current()->resource_area();
3021 VectorSet peel(area);
3022 VectorSet not_peel(area);
3023 Node_List peel_list(area);
3024 Node_List worklist(area);
3025 Node_List sink_list(area);
3026
3027 // Set of cfg nodes to peel are those that are executable from
3028 // the head through last_peel.
3029 assert(worklist.size() == 0, "should be empty");
3030 worklist.push(head);
3031 peel.set(head->_idx);
3032 while (worklist.size() > 0) {
3033 Node *n = worklist.pop();
3034 if (n != last_peel) {
3035 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3036 Node* use = n->fast_out(j);
3037 if (use->is_CFG() &&
3038 loop->is_member(get_loop(use)) &&
3039 !peel.test_set(use->_idx)) {
3040 worklist.push(use);
3041 }
3042 }
3043 }
3044 }
3045
3046 // Set of non-cfg nodes to peel are those that are control
3047 // dependent on the cfg nodes.
3048 uint i;
3049 for(i = 0; i < loop->_body.size(); i++ ) {
3050 Node *n = loop->_body.at(i);
3051 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3052 if (peel.test(n_c->_idx)) {
3053 peel.set(n->_idx);
3054 } else {
3055 not_peel.set(n->_idx);
3056 }
3057 }
3058
3059 // Step 2: move operations from the peeled section down into the
3060 // not-peeled section
3061
3062 // Get a post order schedule of nodes in the peel region
3063 // Result in right-most operand.
3064 scheduled_nodelist(loop, peel, peel_list );
3065
3066 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3067
3068 // For future check for too many new phis
3069 uint old_phi_cnt = 0;
3070 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3071 Node* use = head->fast_out(j);
3072 if (use->is_Phi()) old_phi_cnt++;
3073 }
3074
3075 #if !defined(PRODUCT)
3076 if (TracePartialPeeling) {
3077 tty->print_cr("\npeeled list");
3078 }
3079 #endif
3080
3081 // Evacuate nodes in peel region into the not_peeled region if possible
3082 uint new_phi_cnt = 0;
3083 uint cloned_for_outside_use = 0;
3084 for (i = 0; i < peel_list.size();) {
3085 Node* n = peel_list.at(i);
3086 #if !defined(PRODUCT)
3087 if (TracePartialPeeling) n->dump();
3088 #endif
3089 bool incr = true;
3090 if ( !n->is_CFG() ) {
3091
3092 if ( has_use_in_set(n, not_peel) ) {
3093
3094 // If not used internal to the peeled region,
3095 // move "n" from peeled to not_peeled region.
3096
3097 if ( !has_use_internal_to_set(n, peel, loop) ) {
3098
3099 // if not pinned and not a load (which maybe anti-dependent on a store)
3100 // and not a CMove (Matcher expects only bool->cmove).
3101 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
3102 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
3103 sink_list.push(n);
3104 peel >>= n->_idx; // delete n from peel set.
3105 not_peel <<= n->_idx; // add n to not_peel set.
3106 peel_list.remove(i);
3107 incr = false;
3108 #if !defined(PRODUCT)
3109 if (TracePartialPeeling) {
3110 tty->print_cr("sink to not_peeled region: %d newbb: %d",
3111 n->_idx, get_ctrl(n)->_idx);
3112 }
3113 #endif
3114 }
3115 } else {
3116 // Otherwise check for special def-use cases that span
3117 // the peel/not_peel boundary such as bool->if
3118 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
3119 new_phi_cnt++;
3120 }
3121 }
3122 }
3123 if (incr) i++;
3124 }
3125
3126 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
3127 #if !defined(PRODUCT)
3128 if (TracePartialPeeling) {
3129 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
3130 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3131 }
3132 #endif
3133 if (new_peel_if != NULL) {
3134 remove_cmpi_loop_exit(new_peel_if, loop);
3135 }
3136 // Inhibit more partial peeling on this loop
3137 assert(!head->is_partial_peel_loop(), "not partial peeled");
3138 head->mark_partial_peel_failed();
3139 if (cloned_for_outside_use > 0) {
3140 // Terminate this round of loop opts because
3141 // the graph outside this loop was changed.
3142 C->set_major_progress();
3143 return true;
3144 }
3145 return false;
3146 }
3147
3148 // Step 3: clone loop, retarget control, and insert new phis
3149
3150 // Create new loop head for new phis and to hang
3151 // the nodes being moved (sinked) from the peel region.
3152 LoopNode* new_head = new LoopNode(last_peel, last_peel);
3153 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3154 _igvn.register_new_node_with_optimizer(new_head);
3155 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3156 _igvn.replace_input_of(first_not_peeled, 0, new_head);
3157 set_loop(new_head, loop);
3158 loop->_body.push(new_head);
3159 not_peel.set(new_head->_idx);
3160 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3161 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3162
3163 while (sink_list.size() > 0) {
3164 Node* n = sink_list.pop();
3165 set_ctrl(n, new_head);
3166 }
3167
3168 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3169
3170 clone_loop(loop, old_new, dd, IgnoreStripMined);
3171
3172 const uint clone_exit_idx = 1;
3173 const uint orig_exit_idx = 2;
3174 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
3175
3176 Node* head_clone = old_new[head->_idx];
3177 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
3178 Node* orig_tail_clone = head_clone->in(2);
3179
3180 // Add phi if "def" node is in peel set and "use" is not
3181
3182 for(i = 0; i < peel_list.size(); i++ ) {
3183 Node *def = peel_list.at(i);
3184 if (!def->is_CFG()) {
3185 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3186 Node *use = def->fast_out(j);
3187 if (has_node(use) && use->in(0) != C->top() &&
3188 (!peel.test(use->_idx) ||
3189 (use->is_Phi() && use->in(0) == head)) ) {
3190 worklist.push(use);
3191 }
3192 }
3193 while( worklist.size() ) {
3194 Node *use = worklist.pop();
3195 for (uint j = 1; j < use->req(); j++) {
3196 Node* n = use->in(j);
3197 if (n == def) {
3198
3199 // "def" is in peel set, "use" is not in peel set
3200 // or "use" is in the entry boundary (a phi) of the peel set
3201
3202 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3203
3204 if ( loop->is_member(get_loop( use_c )) ) {
3205 // use is in loop
3206 if (old_new[use->_idx] != NULL) { // null for dead code
3207 Node* use_clone = old_new[use->_idx];
3208 _igvn.replace_input_of(use, j, C->top());
3209 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3210 }
3211 } else {
3212 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3213 // use is not in the loop, check if the live range includes the cut
3214 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3215 if (not_peel.test(lp_if->_idx)) {
3216 assert(j == orig_exit_idx, "use from original loop");
3217 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3218 }
3219 }
3220 }
3221 }
3222 }
3223 }
3224 }
3225
3226 // Step 3b: retarget control
3227
3228 // Redirect control to the new loop head if a cloned node in
3229 // the not_peeled region has control that points into the peeled region.
3230 // This necessary because the cloned peeled region will be outside
3231 // the loop.
3232 // from to
3233 // cloned-peeled <---+
3234 // new_head_clone: | <--+
3235 // cloned-not_peeled in(0) in(0)
3236 // orig-peeled
3237
3238 for(i = 0; i < loop->_body.size(); i++ ) {
3239 Node *n = loop->_body.at(i);
3240 if (!n->is_CFG() && n->in(0) != NULL &&
3241 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3242 Node* n_clone = old_new[n->_idx];
3243 _igvn.replace_input_of(n_clone, 0, new_head_clone);
3244 }
3245 }
3246
3247 // Backedge of the surviving new_head (the clone) is original last_peel
3248 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3249
3250 // Cut first node in original not_peel set
3251 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
3252 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
3253 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
3254
3255 // Copy head_clone back-branch info to original head
3256 // and remove original head's loop entry and
3257 // clone head's back-branch
3258 _igvn.rehash_node_delayed(head); // Multiple edge updates
3259 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
3260 head->set_req(LoopNode::LoopBackControl, C->top());
3261 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3262
3263 // Similarly modify the phis
3264 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3265 Node* use = head->fast_out(k);
3266 if (use->is_Phi() && use->outcnt() > 0) {
3267 Node* use_clone = old_new[use->_idx];
3268 _igvn.rehash_node_delayed(use); // Multiple edge updates
3269 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
3270 use->set_req(LoopNode::LoopBackControl, C->top());
3271 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3272 }
3273 }
3274
3275 // Step 4: update dominator tree and dominator depth
3276
3277 set_idom(head, orig_tail_clone, dd);
3278 recompute_dom_depth();
3279
3280 // Inhibit more partial peeling on this loop
3281 new_head_clone->set_partial_peel_loop();
3282 C->set_major_progress();
3283 loop->record_for_igvn();
3284
3285 #if !defined(PRODUCT)
3286 if (TracePartialPeeling) {
3287 tty->print_cr("\nafter partial peel one iteration");
3288 Node_List wl(area);
3289 Node* t = last_peel;
3290 while (true) {
3291 wl.push(t);
3292 if (t == head_clone) break;
3293 t = idom(t);
3294 }
3295 while (wl.size() > 0) {
3296 Node* tt = wl.pop();
3297 if (tt == head) tty->print_cr("orig head");
3298 else if (tt == new_head_clone) tty->print_cr("new head");
3299 else if (tt == head_clone) tty->print_cr("clone head");
3300 tt->dump();
3301 }
3302 }
3303 #endif
3304 return true;
3305 }
3306
3307 //------------------------------reorg_offsets----------------------------------
3308 // Reorganize offset computations to lower register pressure. Mostly
3309 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3310 // then alive with the post-incremented trip counter forcing an extra
3311 // register move)
3312 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3313 // Perform it only for canonical counted loops.
3314 // Loop's shape could be messed up by iteration_split_impl.
3315 if (!loop->_head->is_CountedLoop())
3316 return;
3317 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3318 return;
3319
3320 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3321 CountedLoopEndNode *cle = cl->loopexit();
3322 Node *exit = cle->proj_out(false);
3323 Node *phi = cl->phi();
3324
3325 // Check for the special case of folks using the pre-incremented
3326 // trip-counter on the fall-out path (forces the pre-incremented
3327 // and post-incremented trip counter to be live at the same time).
3328 // Fix this by adjusting to use the post-increment trip counter.
3329
3330 bool progress = true;
3331 while (progress) {
3332 progress = false;
3333 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3334 Node* use = phi->fast_out(i); // User of trip-counter
3335 if (!has_ctrl(use)) continue;
3336 Node *u_ctrl = get_ctrl(use);
3337 if (use->is_Phi()) {
3338 u_ctrl = NULL;
3339 for (uint j = 1; j < use->req(); j++)
3340 if (use->in(j) == phi)
3341 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3342 }
3343 IdealLoopTree *u_loop = get_loop(u_ctrl);
3344 // Look for loop-invariant use
3345 if (u_loop == loop) continue;
3346 if (loop->is_member(u_loop)) continue;
3347 // Check that use is live out the bottom. Assuming the trip-counter
3348 // update is right at the bottom, uses of of the loop middle are ok.
3349 if (dom_lca(exit, u_ctrl) != exit) continue;
3350 // Hit! Refactor use to use the post-incremented tripcounter.
3351 // Compute a post-increment tripcounter.
3352 Node *opaq = new Opaque2Node( C, cle->incr() );
3353 register_new_node(opaq, exit);
3354 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3355 set_ctrl(neg_stride, C->root());
3356 Node *post = new AddINode( opaq, neg_stride);
3357 register_new_node(post, exit);
3358 _igvn.rehash_node_delayed(use);
3359 for (uint j = 1; j < use->req(); j++) {
3360 if (use->in(j) == phi)
3361 use->set_req(j, post);
3362 }
3363 // Since DU info changed, rerun loop
3364 progress = true;
3365 break;
3366 }
3367 }
3368
3369 }