1 /*
2 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/connode.hpp"
29 #include "opto/divnode.hpp"
30 #include "opto/loopnode.hpp"
31 #include "opto/matcher.hpp"
32 #include "opto/mulnode.hpp"
33 #include "opto/movenode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37
38 //=============================================================================
39 //------------------------------split_thru_phi---------------------------------
40 // Split Node 'n' through merge point if there is enough win.
41 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
42 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
43 // ConvI2L may have type information on it which is unsafe to push up
44 // so disable this for now
45 return NULL;
46 }
47
48 int wins = 0;
49 assert(!n->is_CFG(), "");
50 assert(region->is_Region(), "");
51
52 const Type* type = n->bottom_type();
53 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
54 Node *phi;
55 if (t_oop != NULL && t_oop->is_known_instance_field()) {
56 int iid = t_oop->instance_id();
57 int index = C->get_alias_index(t_oop);
58 int offset = t_oop->offset();
59 phi = new PhiNode(region, type, NULL, iid, index, offset);
60 } else {
61 phi = PhiNode::make_blank(region, n);
62 }
63 uint old_unique = C->unique();
64 for (uint i = 1; i < region->req(); i++) {
65 Node *x;
66 Node* the_clone = NULL;
67 if (region->in(i) == C->top()) {
68 x = C->top(); // Dead path? Use a dead data op
69 } else {
70 x = n->clone(); // Else clone up the data op
71 the_clone = x; // Remember for possible deletion.
72 // Alter data node to use pre-phi inputs
73 if (n->in(0) == region)
74 x->set_req( 0, region->in(i) );
75 for (uint j = 1; j < n->req(); j++) {
76 Node *in = n->in(j);
77 if (in->is_Phi() && in->in(0) == region)
78 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
79 }
80 }
81 // Check for a 'win' on some paths
82 const Type *t = x->Value(&_igvn);
83
84 bool singleton = t->singleton();
85
86 // A TOP singleton indicates that there are no possible values incoming
87 // along a particular edge. In most cases, this is OK, and the Phi will
88 // be eliminated later in an Ideal call. However, we can't allow this to
89 // happen if the singleton occurs on loop entry, as the elimination of
90 // the PhiNode may cause the resulting node to migrate back to a previous
91 // loop iteration.
92 if (singleton && t == Type::TOP) {
93 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
94 // irreducible loop may not be indicated by an affirmative is_Loop());
95 // therefore, the only top we can split thru a phi is on a backedge of
96 // a loop.
97 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
98 }
99
100 if (singleton) {
101 wins++;
102 x = ((PhaseGVN&)_igvn).makecon(t);
103 } else {
104 // We now call Identity to try to simplify the cloned node.
105 // Note that some Identity methods call phase->type(this).
106 // Make sure that the type array is big enough for
107 // our new node, even though we may throw the node away.
108 // (Note: This tweaking with igvn only works because x is a new node.)
109 _igvn.set_type(x, t);
110 // If x is a TypeNode, capture any more-precise type permanently into Node
111 // otherwise it will be not updated during igvn->transform since
112 // igvn->type(x) is set to x->Value() already.
113 x->raise_bottom_type(t);
114 Node *y = x->Identity(&_igvn);
115 if (y != x) {
116 wins++;
117 x = y;
118 } else {
119 y = _igvn.hash_find(x);
120 if (y) {
121 wins++;
122 x = y;
123 } else {
124 // Else x is a new node we are keeping
125 // We do not need register_new_node_with_optimizer
126 // because set_type has already been called.
127 _igvn._worklist.push(x);
128 }
129 }
130 }
131 if (x != the_clone && the_clone != NULL)
132 _igvn.remove_dead_node(the_clone);
133 phi->set_req( i, x );
134 }
135 // Too few wins?
136 if (wins <= policy) {
137 _igvn.remove_dead_node(phi);
138 return NULL;
139 }
140
141 // Record Phi
142 register_new_node( phi, region );
143
144 for (uint i2 = 1; i2 < phi->req(); i2++) {
145 Node *x = phi->in(i2);
146 // If we commoned up the cloned 'x' with another existing Node,
147 // the existing Node picks up a new use. We need to make the
148 // existing Node occur higher up so it dominates its uses.
149 Node *old_ctrl;
150 IdealLoopTree *old_loop;
151
152 if (x->is_Con()) {
153 // Constant's control is always root.
154 set_ctrl(x, C->root());
155 continue;
156 }
157 // The occasional new node
158 if (x->_idx >= old_unique) { // Found a new, unplaced node?
159 old_ctrl = NULL;
160 old_loop = NULL; // Not in any prior loop
161 } else {
162 old_ctrl = get_ctrl(x);
163 old_loop = get_loop(old_ctrl); // Get prior loop
164 }
165 // New late point must dominate new use
166 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
167 if (new_ctrl == old_ctrl) // Nothing is changed
168 continue;
169
170 IdealLoopTree *new_loop = get_loop(new_ctrl);
171
172 // Don't move x into a loop if its uses are
173 // outside of loop. Otherwise x will be cloned
174 // for each use outside of this loop.
175 IdealLoopTree *use_loop = get_loop(region);
176 if (!new_loop->is_member(use_loop) &&
177 (old_loop == NULL || !new_loop->is_member(old_loop))) {
178 // Take early control, later control will be recalculated
179 // during next iteration of loop optimizations.
180 new_ctrl = get_early_ctrl(x);
181 new_loop = get_loop(new_ctrl);
182 }
183 // Set new location
184 set_ctrl(x, new_ctrl);
185 // If changing loop bodies, see if we need to collect into new body
186 if (old_loop != new_loop) {
187 if (old_loop && !old_loop->_child)
188 old_loop->_body.yank(x);
189 if (!new_loop->_child)
190 new_loop->_body.push(x); // Collect body info
191 }
192 }
193
194 return phi;
195 }
196
197 //------------------------------dominated_by------------------------------------
198 // Replace the dominated test with an obvious true or false. Place it on the
199 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
200 // live path up to the dominating control.
201 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
202 #ifndef PRODUCT
203 if (VerifyLoopOptimizations && PrintOpto) tty->print_cr("dominating test");
204 #endif
205
206
207 // prevdom is the dominating projection of the dominating test.
208 assert( iff->is_If(), "" );
209 assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
210 int pop = prevdom->Opcode();
211 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
212 if (flip) {
213 if (pop == Op_IfTrue)
214 pop = Op_IfFalse;
215 else
216 pop = Op_IfTrue;
217 }
218 // 'con' is set to true or false to kill the dominated test.
219 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
220 set_ctrl(con, C->root()); // Constant gets a new use
221 // Hack the dominated test
222 _igvn.replace_input_of(iff, 1, con);
223
224 // If I dont have a reachable TRUE and FALSE path following the IfNode then
225 // I can assume this path reaches an infinite loop. In this case it's not
226 // important to optimize the data Nodes - either the whole compilation will
227 // be tossed or this path (and all data Nodes) will go dead.
228 if (iff->outcnt() != 2) return;
229
230 // Make control-dependent data Nodes on the live path (path that will remain
231 // once the dominated IF is removed) become control-dependent on the
232 // dominating projection.
233 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
234
235 // Loop predicates may have depending checks which should not
236 // be skipped. For example, range check predicate has two checks
237 // for lower and upper bounds.
238 if (dp == NULL)
239 return;
240
241 ProjNode* dp_proj = dp->as_Proj();
242 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
243 if (exclude_loop_predicate &&
244 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
245 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
246 // If this is a range check (IfNode::is_range_check), do not
247 // reorder because Compile::allow_range_check_smearing might have
248 // changed the check.
249 return; // Let IGVN transformation change control dependence.
250 }
251
252 IdealLoopTree *old_loop = get_loop(dp);
253
254 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
255 Node* cd = dp->fast_out(i); // Control-dependent node
256 if (cd->depends_only_on_test()) {
257 assert(cd->in(0) == dp, "");
258 _igvn.replace_input_of(cd, 0, prevdom);
259 set_early_ctrl(cd);
260 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
261 if (old_loop != new_loop) {
262 if (!old_loop->_child) old_loop->_body.yank(cd);
263 if (!new_loop->_child) new_loop->_body.push(cd);
264 }
265 --i;
266 --imax;
267 }
268 }
269 }
270
271 //------------------------------has_local_phi_input----------------------------
272 // Return TRUE if 'n' has Phi inputs from its local block and no other
273 // block-local inputs (all non-local-phi inputs come from earlier blocks)
274 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
275 Node *n_ctrl = get_ctrl(n);
276 // See if some inputs come from a Phi in this block, or from before
277 // this block.
278 uint i;
279 for( i = 1; i < n->req(); i++ ) {
280 Node *phi = n->in(i);
281 if( phi->is_Phi() && phi->in(0) == n_ctrl )
282 break;
283 }
284 if( i >= n->req() )
285 return NULL; // No Phi inputs; nowhere to clone thru
286
287 // Check for inputs created between 'n' and the Phi input. These
288 // must split as well; they have already been given the chance
289 // (courtesy of a post-order visit) and since they did not we must
290 // recover the 'cost' of splitting them by being very profitable
291 // when splitting 'n'. Since this is unlikely we simply give up.
292 for( i = 1; i < n->req(); i++ ) {
293 Node *m = n->in(i);
294 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
295 // We allow the special case of AddP's with no local inputs.
296 // This allows us to split-up address expressions.
297 if (m->is_AddP() &&
298 get_ctrl(m->in(2)) != n_ctrl &&
299 get_ctrl(m->in(3)) != n_ctrl) {
300 // Move the AddP up to dominating point
301 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
302 continue;
303 }
304 return NULL;
305 }
306 }
307
308 return n_ctrl;
309 }
310
311 //------------------------------remix_address_expressions----------------------
312 // Rework addressing expressions to get the most loop-invariant stuff
313 // moved out. We'd like to do all associative operators, but it's especially
314 // important (common) to do address expressions.
315 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
316 if (!has_ctrl(n)) return NULL;
317 Node *n_ctrl = get_ctrl(n);
318 IdealLoopTree *n_loop = get_loop(n_ctrl);
319
320 // See if 'n' mixes loop-varying and loop-invariant inputs and
321 // itself is loop-varying.
322
323 // Only interested in binary ops (and AddP)
324 if( n->req() < 3 || n->req() > 4 ) return NULL;
325
326 Node *n1_ctrl = get_ctrl(n->in( 1));
327 Node *n2_ctrl = get_ctrl(n->in( 2));
328 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
329 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
330 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
331 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
332
333 // Does one of my inputs spin in a tighter loop than self?
334 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
335 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
336 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
337 return NULL; // Leave well enough alone
338
339 // Is at least one of my inputs loop-invariant?
340 if( n1_loop == n_loop &&
341 n2_loop == n_loop &&
342 n3_loop == n_loop )
343 return NULL; // No loop-invariant inputs
344
345
346 int n_op = n->Opcode();
347
348 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
349 if( n_op == Op_LShiftI ) {
350 // Scale is loop invariant
351 Node *scale = n->in(2);
352 Node *scale_ctrl = get_ctrl(scale);
353 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
354 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
355 return NULL;
356 const TypeInt *scale_t = scale->bottom_type()->isa_int();
357 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
358 return NULL; // Dont bother with byte/short masking
359 // Add must vary with loop (else shift would be loop-invariant)
360 Node *add = n->in(1);
361 Node *add_ctrl = get_ctrl(add);
362 IdealLoopTree *add_loop = get_loop(add_ctrl);
363 //assert( n_loop == add_loop, "" );
364 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
365
366 // Convert I-V into I+ (0-V); same for V-I
367 if( add->Opcode() == Op_SubI &&
368 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
369 Node *zero = _igvn.intcon(0);
370 set_ctrl(zero, C->root());
371 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
372 register_new_node( neg, get_ctrl(add->in(2) ) );
373 add = new AddINode( add->in(1), neg );
374 register_new_node( add, add_ctrl );
375 }
376 if( add->Opcode() != Op_AddI ) return NULL;
377 // See if one add input is loop invariant
378 Node *add_var = add->in(1);
379 Node *add_var_ctrl = get_ctrl(add_var);
380 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
381 Node *add_invar = add->in(2);
382 Node *add_invar_ctrl = get_ctrl(add_invar);
383 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
384 if( add_var_loop == n_loop ) {
385 } else if( add_invar_loop == n_loop ) {
386 // Swap to find the invariant part
387 add_invar = add_var;
388 add_invar_ctrl = add_var_ctrl;
389 add_invar_loop = add_var_loop;
390 add_var = add->in(2);
391 Node *add_var_ctrl = get_ctrl(add_var);
392 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
393 } else // Else neither input is loop invariant
394 return NULL;
395 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
396 return NULL; // No invariant part of the add?
397
398 // Yes! Reshape address expression!
399 Node *inv_scale = new LShiftINode( add_invar, scale );
400 Node *inv_scale_ctrl =
401 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
402 add_invar_ctrl : scale_ctrl;
403 register_new_node( inv_scale, inv_scale_ctrl );
404 Node *var_scale = new LShiftINode( add_var, scale );
405 register_new_node( var_scale, n_ctrl );
406 Node *var_add = new AddINode( var_scale, inv_scale );
407 register_new_node( var_add, n_ctrl );
408 _igvn.replace_node( n, var_add );
409 return var_add;
410 }
411
412 // Replace (I+V) with (V+I)
413 if( n_op == Op_AddI ||
414 n_op == Op_AddL ||
415 n_op == Op_AddF ||
416 n_op == Op_AddD ||
417 n_op == Op_MulI ||
418 n_op == Op_MulL ||
419 n_op == Op_MulF ||
420 n_op == Op_MulD ) {
421 if( n2_loop == n_loop ) {
422 assert( n1_loop != n_loop, "" );
423 n->swap_edges(1, 2);
424 }
425 }
426
427 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
428 // but not if I2 is a constant.
429 if( n_op == Op_AddP ) {
430 if( n2_loop == n_loop && n3_loop != n_loop ) {
431 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
432 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
433 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
434 IdealLoopTree *n22loop = get_loop( n22_ctrl );
435 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
436 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
437 n23_loop == n_loop ) {
438 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
439 // Stuff new AddP in the loop preheader
440 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
441 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
442 register_new_node( add2, n_ctrl );
443 _igvn.replace_node( n, add2 );
444 return add2;
445 }
446 }
447 }
448
449 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
450 if( n2_loop != n_loop && n3_loop == n_loop ) {
451 if( n->in(3)->Opcode() == Op_AddI ) {
452 Node *V = n->in(3)->in(1);
453 Node *I = n->in(3)->in(2);
454 if( is_member(n_loop,get_ctrl(V)) ) {
455 } else {
456 Node *tmp = V; V = I; I = tmp;
457 }
458 if( !is_member(n_loop,get_ctrl(I)) ) {
459 Node *add1 = new AddPNode( n->in(1), n->in(2), I );
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, V );
463 register_new_node( add2, n_ctrl );
464 _igvn.replace_node( n, add2 );
465 return add2;
466 }
467 }
468 }
469 }
470
471 return NULL;
472 }
473
474 //------------------------------conditional_move-------------------------------
475 // Attempt to replace a Phi with a conditional move. We have some pretty
476 // strict profitability requirements. All Phis at the merge point must
477 // be converted, so we can remove the control flow. We need to limit the
478 // number of c-moves to a small handful. All code that was in the side-arms
479 // of the CFG diamond is now speculatively executed. This code has to be
480 // "cheap enough". We are pretty much limited to CFG diamonds that merge
481 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
482 Node *PhaseIdealLoop::conditional_move( Node *region ) {
483
484 assert(region->is_Region(), "sanity check");
485 if (region->req() != 3) return NULL;
486
487 // Check for CFG diamond
488 Node *lp = region->in(1);
489 Node *rp = region->in(2);
490 if (!lp || !rp) return NULL;
491 Node *lp_c = lp->in(0);
492 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
493 IfNode *iff = lp_c->as_If();
494
495 // Check for ops pinned in an arm of the diamond.
496 // Can't remove the control flow in this case
497 if (lp->outcnt() > 1) return NULL;
498 if (rp->outcnt() > 1) return NULL;
499
500 IdealLoopTree* r_loop = get_loop(region);
501 assert(r_loop == get_loop(iff), "sanity");
502 // Always convert to CMOVE if all results are used only outside this loop.
503 bool used_inside_loop = (r_loop == _ltree_root);
504
505 // Check profitability
506 int cost = 0;
507 int phis = 0;
508 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
509 Node *out = region->fast_out(i);
510 if (!out->is_Phi()) continue; // Ignore other control edges, etc
511 phis++;
512 PhiNode* phi = out->as_Phi();
513 BasicType bt = phi->type()->basic_type();
514 switch (bt) {
515 case T_FLOAT:
516 case T_DOUBLE: {
517 cost += Matcher::float_cmove_cost(); // Could be very expensive
518 break;
519 }
520 case T_LONG: {
521 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
522 }
523 case T_INT: // These all CMOV fine
524 case T_ADDRESS: { // (RawPtr)
525 cost++;
526 break;
527 }
528 case T_NARROWOOP: // Fall through
529 case T_OBJECT: { // Base oops are OK, but not derived oops
530 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
531 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
532 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
533 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
534 // have a Phi for the base here that we convert to a CMOVE all is well
535 // and good. But if the base is dead, we'll not make a CMOVE. Later
536 // the allocator will have to produce a base by creating a CMOVE of the
537 // relevant bases. This puts the allocator in the business of
538 // manufacturing expensive instructions, generally a bad plan.
539 // Just Say No to Conditionally-Moved Derived Pointers.
540 if (tp && tp->offset() != 0)
541 return NULL;
542 cost++;
543 break;
544 }
545 default:
546 return NULL; // In particular, can't do memory or I/O
547 }
548 // Add in cost any speculative ops
549 for (uint j = 1; j < region->req(); j++) {
550 Node *proj = region->in(j);
551 Node *inp = phi->in(j);
552 if (get_ctrl(inp) == proj) { // Found local op
553 cost++;
554 // Check for a chain of dependent ops; these will all become
555 // speculative in a CMOV.
556 for (uint k = 1; k < inp->req(); k++)
557 if (get_ctrl(inp->in(k)) == proj)
558 cost += ConditionalMoveLimit; // Too much speculative goo
559 }
560 }
561 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
562 // This will likely Split-If, a higher-payoff operation.
563 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
564 Node* use = phi->fast_out(k);
565 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
566 cost += ConditionalMoveLimit;
567 // Is there a use inside the loop?
568 // Note: check only basic types since CMoveP is pinned.
569 if (!used_inside_loop && is_java_primitive(bt)) {
570 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
571 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
572 used_inside_loop = true;
573 }
574 }
575 }
576 }
577 Node* bol = iff->in(1);
578 assert(bol->Opcode() == Op_Bool, "");
579 int cmp_op = bol->in(1)->Opcode();
580 // It is expensive to generate flags from a float compare.
581 // Avoid duplicated float compare.
582 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
583
584 float infrequent_prob = PROB_UNLIKELY_MAG(3);
585 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
586 if (used_inside_loop) {
587 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
588
589 // BlockLayoutByFrequency optimization moves infrequent branch
590 // from hot path. No point in CMOV'ing in such case (110 is used
591 // instead of 100 to take into account not exactness of float value).
592 if (BlockLayoutByFrequency) {
593 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
594 }
595 }
596 // Check for highly predictable branch. No point in CMOV'ing if
597 // we are going to predict accurately all the time.
598 if (iff->_prob < infrequent_prob ||
599 iff->_prob > (1.0f - infrequent_prob))
600 return NULL;
601
602 // --------------
603 // Now replace all Phis with CMOV's
604 Node *cmov_ctrl = iff->in(0);
605 uint flip = (lp->Opcode() == Op_IfTrue);
606 while (1) {
607 PhiNode* phi = NULL;
608 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
609 Node *out = region->fast_out(i);
610 if (out->is_Phi()) {
611 phi = out->as_Phi();
612 break;
613 }
614 }
615 if (phi == NULL) break;
616 #ifndef PRODUCT
617 if (PrintOpto && VerifyLoopOptimizations) tty->print_cr("CMOV");
618 #endif
619 // Move speculative ops
620 for (uint j = 1; j < region->req(); j++) {
621 Node *proj = region->in(j);
622 Node *inp = phi->in(j);
623 if (get_ctrl(inp) == proj) { // Found local op
624 #ifndef PRODUCT
625 if (PrintOpto && VerifyLoopOptimizations) {
626 tty->print(" speculate: ");
627 inp->dump();
628 }
629 #endif
630 set_ctrl(inp, cmov_ctrl);
631 }
632 }
633 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
634 register_new_node( cmov, cmov_ctrl );
635 _igvn.replace_node( phi, cmov );
636 #ifndef PRODUCT
637 if (TraceLoopOpts) {
638 tty->print("CMOV ");
639 r_loop->dump_head();
640 if (Verbose) {
641 bol->in(1)->dump(1);
642 cmov->dump(1);
643 }
644 }
645 if (VerifyLoopOptimizations) verify();
646 #endif
647 }
648
649 // The useless CFG diamond will fold up later; see the optimization in
650 // RegionNode::Ideal.
651 _igvn._worklist.push(region);
652
653 return iff->in(1);
654 }
655
656 #ifdef ASSERT
657 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
658 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
659 Node* u = m->fast_out(i);
660 if (u->is_CFG()) {
661 if (u->Opcode() == Op_NeverBranch) {
662 u = ((NeverBranchNode*)u)->proj_out(0);
663 enqueue_cfg_uses(u, wq);
664 } else {
665 wq.push(u);
666 }
667 }
668 }
669 }
670 #endif
671
672 // Try moving a store out of a loop, right before the loop
673 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
674 // Store has to be first in the loop body
675 IdealLoopTree *n_loop = get_loop(n_ctrl);
676 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop()) {
677 assert(n->in(0), "store should have control set");
678 Node* address = n->in(MemNode::Address);
679 Node* value = n->in(MemNode::ValueIn);
680 Node* mem = n->in(MemNode::Memory);
681 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
682 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
683
684 // - address and value must be loop invariant
685 // - memory must be a memory Phi for the loop
686 // - Store must be the only store on this memory slice in the
687 // loop: if there's another store following this one then value
688 // written at iteration i by the second store could be overwritten
689 // at iteration i+n by the first store: it's not safe to move the
690 // first store out of the loop
691 // - nothing must observe the Phi memory: it guarantees no read
692 // before the store and no early exit out of the loop
693 // With those conditions, we are also guaranteed the store post
694 // dominates the loop head. Otherwise there would be extra Phi
695 // involved between the loop's Phi and the store.
696
697 if (!n_loop->is_member(address_loop) &&
698 !n_loop->is_member(value_loop) &&
699 mem->is_Phi() && mem->in(0) == n_loop->_head &&
700 mem->outcnt() == 1 &&
701 mem->in(LoopNode::LoopBackControl) == n) {
702
703 #ifdef ASSERT
704 // Verify that store's control does post dominate loop entry and
705 // that there's no early exit of the loop before the store.
706 bool ctrl_ok = false;
707 {
708 // Follow control from loop head until n, we exit the loop or
709 // we reach the tail
710 ResourceMark rm;
711 Unique_Node_List wq;
712 wq.push(n_loop->_head);
713 assert(n_loop->_tail != NULL, "need a tail");
714 for (uint next = 0; next < wq.size(); ++next) {
715 Node *m = wq.at(next);
716 if (m == n->in(0)) {
717 ctrl_ok = true;
718 continue;
719 }
720 assert(!has_ctrl(m), "should be CFG");
721 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
722 ctrl_ok = false;
723 break;
724 }
725 enqueue_cfg_uses(m, wq);
726 }
727 }
728 assert(ctrl_ok, "bad control");
729 #endif
730
731 // move the Store
732 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
733 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
734 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
735 // Disconnect the phi now. An empty phi can confuse other
736 // optimizations in this pass of loop opts.
737 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
738 n_loop->_body.yank(mem);
739
740 IdealLoopTree* new_loop = get_loop(n->in(0));
741 set_ctrl_and_loop(n, n->in(0));
742
743 return n;
744 }
745 }
746 return NULL;
747 }
748
749 // Try moving a store out of a loop, right after the loop
750 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
751 if (n->is_Store()) {
752 assert(n->in(0), "store should have control set");
753 Node *n_ctrl = get_ctrl(n);
754 IdealLoopTree *n_loop = get_loop(n_ctrl);
755 // Store must be in a loop
756 if (n_loop != _ltree_root && !n_loop->_irreducible) {
757 Node* address = n->in(MemNode::Address);
758 Node* value = n->in(MemNode::ValueIn);
759 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
760 // address must be loop invariant
761 if (!n_loop->is_member(address_loop)) {
762 // Store must be last on this memory slice in the loop and
763 // nothing in the loop must observe it
764 Node* phi = NULL;
765 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
766 Node* u = n->fast_out(i);
767 if (has_ctrl(u)) { // control use?
768 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
769 if (!n_loop->is_member(u_loop)) {
770 continue;
771 }
772 if (u->is_Phi() && u->in(0) == n_loop->_head) {
773 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
774 assert(phi == NULL, "already found");
775 phi = u;
776 continue;
777 }
778 }
779 phi = NULL;
780 break;
781 }
782 if (phi != NULL) {
783 // Nothing in the loop before the store (next iteration)
784 // must observe the stored value
785 bool mem_ok = true;
786 {
787 ResourceMark rm;
788 Unique_Node_List wq;
789 wq.push(phi);
790 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
791 Node *m = wq.at(next);
792 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
793 Node* u = m->fast_out(i);
794 if (u->is_Store() || u->is_Phi()) {
795 if (u != n) {
796 wq.push(u);
797 mem_ok = (wq.size() <= 10);
798 }
799 } else {
800 mem_ok = false;
801 break;
802 }
803 }
804 }
805 }
806 if (mem_ok) {
807 // Move the Store out of the loop creating clones along
808 // all paths out of the loop that observe the stored value
809 _igvn.rehash_node_delayed(phi);
810 int count = phi->replace_edge(n, n->in(MemNode::Memory));
811 assert(count > 0, "inconsistent phi");
812 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
813 Node* u = n->fast_out(i);
814 Node* c = get_ctrl(u);
815
816 if (u->is_Phi()) {
817 c = u->in(0)->in(u->find_edge(n));
818 }
819 IdealLoopTree *u_loop = get_loop(c);
820 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
821 while(true) {
822 Node* next_c = find_non_split_ctrl(idom(c));
823 if (n_loop->is_member(get_loop(next_c))) {
824 break;
825 }
826 c = next_c;
827 }
828
829 Node* st = n->clone();
830 st->set_req(0, c);
831 _igvn.register_new_node_with_optimizer(st);
832
833 set_ctrl(st, c);
834 IdealLoopTree* new_loop = get_loop(c);
835 assert(new_loop != n_loop, "should be moved out of loop");
836 if (new_loop->_child == NULL) new_loop->_body.push(st);
837
838 _igvn.replace_input_of(u, u->find_edge(n), st);
839 --imax;
840 --i;
841 }
842
843
844 assert(n->outcnt() == 0, "all uses should be gone");
845 _igvn.replace_input_of(n, MemNode::Memory, C->top());
846 // Disconnect the phi now. An empty phi can confuse other
847 // optimizations in this pass of loop opts..
848 if (phi->in(LoopNode::LoopBackControl) == phi) {
849 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
850 n_loop->_body.yank(phi);
851 }
852 }
853 }
854 }
855 }
856 }
857 }
858
859 //------------------------------split_if_with_blocks_pre-----------------------
860 // Do the real work in a non-recursive function. Data nodes want to be
861 // cloned in the pre-order so they can feed each other nicely.
862 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
863 // Cloning these guys is unlikely to win
864 int n_op = n->Opcode();
865 if( n_op == Op_MergeMem ) return n;
866 if( n->is_Proj() ) return n;
867 // Do not clone-up CmpFXXX variations, as these are always
868 // followed by a CmpI
869 if( n->is_Cmp() ) return n;
870 // Attempt to use a conditional move instead of a phi/branch
871 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
872 Node *cmov = conditional_move( n );
873 if( cmov ) return cmov;
874 }
875 if( n->is_CFG() || n->is_LoadStore() )
876 return n;
877 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
878 n_op == Op_Opaque2 ) {
879 if( !C->major_progress() ) // If chance of no more loop opts...
880 _igvn._worklist.push(n); // maybe we'll remove them
881 return n;
882 }
883
884 if( n->is_Con() ) return n; // No cloning for Con nodes
885
886 Node *n_ctrl = get_ctrl(n);
887 if( !n_ctrl ) return n; // Dead node
888
889 Node* res = try_move_store_before_loop(n, n_ctrl);
890 if (res != NULL) {
891 return n;
892 }
893
894 // Attempt to remix address expressions for loop invariants
895 Node *m = remix_address_expressions( n );
896 if( m ) return m;
897
898 // Determine if the Node has inputs from some local Phi.
899 // Returns the block to clone thru.
900 Node *n_blk = has_local_phi_input( n );
901 if( !n_blk ) return n;
902
903 // Do not clone the trip counter through on a CountedLoop
904 // (messes up the canonical shape).
905 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
906
907 // Check for having no control input; not pinned. Allow
908 // dominating control.
909 if (n->in(0)) {
910 Node *dom = idom(n_blk);
911 if (dom_lca(n->in(0), dom) != n->in(0)) {
912 return n;
913 }
914 }
915 // Policy: when is it profitable. You must get more wins than
916 // policy before it is considered profitable. Policy is usually 0,
917 // so 1 win is considered profitable. Big merges will require big
918 // cloning, so get a larger policy.
919 int policy = n_blk->req() >> 2;
920
921 // If the loop is a candidate for range check elimination,
922 // delay splitting through it's phi until a later loop optimization
923 if (n_blk->is_CountedLoop()) {
924 IdealLoopTree *lp = get_loop(n_blk);
925 if (lp && lp->_rce_candidate) {
926 return n;
927 }
928 }
929
930 // Use same limit as split_if_with_blocks_post
931 if( C->live_nodes() > 35000 ) return n; // Method too big
932
933 // Split 'n' through the merge point if it is profitable
934 Node *phi = split_thru_phi( n, n_blk, policy );
935 if (!phi) return n;
936
937 // Found a Phi to split thru!
938 // Replace 'n' with the new phi
939 _igvn.replace_node( n, phi );
940 // Moved a load around the loop, 'en-registering' something.
941 if (n_blk->is_Loop() && n->is_Load() &&
942 !phi->in(LoopNode::LoopBackControl)->is_Load())
943 C->set_major_progress();
944
945 return phi;
946 }
947
948 static bool merge_point_too_heavy(Compile* C, Node* region) {
949 // Bail out if the region and its phis have too many users.
950 int weight = 0;
951 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
952 weight += region->fast_out(i)->outcnt();
953 }
954 int nodes_left = C->max_node_limit() - C->live_nodes();
955 if (weight * 8 > nodes_left) {
956 #ifndef PRODUCT
957 if (PrintOpto)
958 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
959 #endif
960 return true;
961 } else {
962 return false;
963 }
964 }
965
966 static bool merge_point_safe(Node* region) {
967 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
968 // having a PhiNode input. This sidesteps the dangerous case where the split
969 // ConvI2LNode may become TOP if the input Value() does not
970 // overlap the ConvI2L range, leaving a node which may not dominate its
971 // uses.
972 // A better fix for this problem can be found in the BugTraq entry, but
973 // expediency for Mantis demands this hack.
974 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
975 // split_if_with_blocks from splitting a block because we could not move around
976 // the FastLockNode.
977 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
978 Node* n = region->fast_out(i);
979 if (n->is_Phi()) {
980 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
981 Node* m = n->fast_out(j);
982 if (m->is_FastLock())
983 return false;
984 #ifdef _LP64
985 if (m->Opcode() == Op_ConvI2L)
986 return false;
987 #endif
988 }
989 }
990 }
991 return true;
992 }
993
994
995 //------------------------------place_near_use---------------------------------
996 // Place some computation next to use but not inside inner loops.
997 // For inner loop uses move it to the preheader area.
998 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
999 IdealLoopTree *u_loop = get_loop( useblock );
1000 return (u_loop->_irreducible || u_loop->_child)
1001 ? useblock
1002 : u_loop->_head->in(LoopNode::EntryControl);
1003 }
1004
1005
1006 //------------------------------split_if_with_blocks_post----------------------
1007 // Do the real work in a non-recursive function. CFG hackery wants to be
1008 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1009 // info.
1010 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1011
1012 // Cloning Cmp through Phi's involves the split-if transform.
1013 // FastLock is not used by an If
1014 if( n->is_Cmp() && !n->is_FastLock() ) {
1015 if( C->live_nodes() > 35000 ) return; // Method too big
1016
1017 // Do not do 'split-if' if irreducible loops are present.
1018 if( _has_irreducible_loops )
1019 return;
1020
1021 Node *n_ctrl = get_ctrl(n);
1022 // Determine if the Node has inputs from some local Phi.
1023 // Returns the block to clone thru.
1024 Node *n_blk = has_local_phi_input( n );
1025 if( n_blk != n_ctrl ) return;
1026
1027 if( merge_point_too_heavy(C, n_ctrl) )
1028 return;
1029
1030 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1031 Node *bol = n->unique_out();
1032 assert( bol->is_Bool(), "expect a bool here" );
1033 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1034 Node *iff = bol->unique_out();
1035
1036 // Check some safety conditions
1037 if( iff->is_If() ) { // Classic split-if?
1038 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1039 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1040 // Can't split CMove with different control edge.
1041 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1042 if( get_ctrl(iff->in(2)) == n_ctrl ||
1043 get_ctrl(iff->in(3)) == n_ctrl )
1044 return; // Inputs not yet split-up
1045 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1046 return; // Loop-invar test gates loop-varying CMOVE
1047 }
1048 } else {
1049 return; // some other kind of node, such as an Allocate
1050 }
1051
1052 // Do not do 'split-if' if some paths are dead. First do dead code
1053 // elimination and then see if its still profitable.
1054 for( uint i = 1; i < n_ctrl->req(); i++ )
1055 if( n_ctrl->in(i) == C->top() )
1056 return;
1057
1058 // When is split-if profitable? Every 'win' on means some control flow
1059 // goes dead, so it's almost always a win.
1060 int policy = 0;
1061 // If trying to do a 'Split-If' at the loop head, it is only
1062 // profitable if the cmp folds up on BOTH paths. Otherwise we
1063 // risk peeling a loop forever.
1064
1065 // CNC - Disabled for now. Requires careful handling of loop
1066 // body selection for the cloned code. Also, make sure we check
1067 // for any input path not being in the same loop as n_ctrl. For
1068 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1069 // because the alternative loop entry points won't be converted
1070 // into LoopNodes.
1071 IdealLoopTree *n_loop = get_loop(n_ctrl);
1072 for( uint j = 1; j < n_ctrl->req(); j++ )
1073 if( get_loop(n_ctrl->in(j)) != n_loop )
1074 return;
1075
1076 // Check for safety of the merge point.
1077 if( !merge_point_safe(n_ctrl) ) {
1078 return;
1079 }
1080
1081 // Split compare 'n' through the merge point if it is profitable
1082 Node *phi = split_thru_phi( n, n_ctrl, policy );
1083 if( !phi ) return;
1084
1085 // Found a Phi to split thru!
1086 // Replace 'n' with the new phi
1087 _igvn.replace_node( n, phi );
1088
1089 // Now split the bool up thru the phi
1090 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1091 guarantee(bolphi != NULL, "null boolean phi node");
1092
1093 _igvn.replace_node( bol, bolphi );
1094 assert( iff->in(1) == bolphi, "" );
1095
1096 if( bolphi->Value(&_igvn)->singleton() )
1097 return;
1098
1099 // Conditional-move? Must split up now
1100 if( !iff->is_If() ) {
1101 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1102 _igvn.replace_node( iff, cmovphi );
1103 return;
1104 }
1105
1106 // Now split the IF
1107 do_split_if( iff );
1108 return;
1109 }
1110
1111 // Check for an IF ready to split; one that has its
1112 // condition codes input coming from a Phi at the block start.
1113 int n_op = n->Opcode();
1114
1115 // Check for an IF being dominated by another IF same test
1116 if (n_op == Op_If) {
1117 Node *bol = n->in(1);
1118 uint max = bol->outcnt();
1119 // Check for same test used more than once?
1120 if (max > 1 && bol->is_Bool()) {
1121 // Search up IDOMs to see if this IF is dominated.
1122 Node *cutoff = get_ctrl(bol);
1123
1124 // Now search up IDOMs till cutoff, looking for a dominating test
1125 Node *prevdom = n;
1126 Node *dom = idom(prevdom);
1127 while (dom != cutoff) {
1128 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1129 // Replace the dominated test with an obvious true or false.
1130 // Place it on the IGVN worklist for later cleanup.
1131 C->set_major_progress();
1132 dominated_by(prevdom, n, false, true);
1133 #ifndef PRODUCT
1134 if( VerifyLoopOptimizations ) verify();
1135 #endif
1136 return;
1137 }
1138 prevdom = dom;
1139 dom = idom(prevdom);
1140 }
1141 }
1142 }
1143
1144 // See if a shared loop-varying computation has no loop-varying uses.
1145 // Happens if something is only used for JVM state in uncommon trap exits,
1146 // like various versions of induction variable+offset. Clone the
1147 // computation per usage to allow it to sink out of the loop.
1148 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1149 Node *n_ctrl = get_ctrl(n);
1150 IdealLoopTree *n_loop = get_loop(n_ctrl);
1151 if( n_loop != _ltree_root ) {
1152 DUIterator_Fast imax, i = n->fast_outs(imax);
1153 for (; i < imax; i++) {
1154 Node* u = n->fast_out(i);
1155 if( !has_ctrl(u) ) break; // Found control user
1156 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1157 if( u_loop == n_loop ) break; // Found loop-varying use
1158 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1159 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1160 }
1161 bool did_break = (i < imax); // Did we break out of the previous loop?
1162 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1163 Node *late_load_ctrl = NULL;
1164 if (n->is_Load()) {
1165 // If n is a load, get and save the result from get_late_ctrl(),
1166 // to be later used in calculating the control for n's clones.
1167 clear_dom_lca_tags();
1168 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1169 }
1170 // If n is a load, and the late control is the same as the current
1171 // control, then the cloning of n is a pointless exercise, because
1172 // GVN will ensure that we end up where we started.
1173 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1174 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1175 Node *u = n->last_out(j); // Clone private computation per use
1176 _igvn.rehash_node_delayed(u);
1177 Node *x = n->clone(); // Clone computation
1178 Node *x_ctrl = NULL;
1179 if( u->is_Phi() ) {
1180 // Replace all uses of normal nodes. Replace Phi uses
1181 // individually, so the separate Nodes can sink down
1182 // different paths.
1183 uint k = 1;
1184 while( u->in(k) != n ) k++;
1185 u->set_req( k, x );
1186 // x goes next to Phi input path
1187 x_ctrl = u->in(0)->in(k);
1188 --j;
1189 } else { // Normal use
1190 // Replace all uses
1191 for( uint k = 0; k < u->req(); k++ ) {
1192 if( u->in(k) == n ) {
1193 u->set_req( k, x );
1194 --j;
1195 }
1196 }
1197 x_ctrl = get_ctrl(u);
1198 }
1199
1200 // Find control for 'x' next to use but not inside inner loops.
1201 // For inner loop uses get the preheader area.
1202 x_ctrl = place_near_use(x_ctrl);
1203
1204 if (n->is_Load()) {
1205 // For loads, add a control edge to a CFG node outside of the loop
1206 // to force them to not combine and return back inside the loop
1207 // during GVN optimization (4641526).
1208 //
1209 // Because we are setting the actual control input, factor in
1210 // the result from get_late_ctrl() so we respect any
1211 // anti-dependences. (6233005).
1212 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1213
1214 // Don't allow the control input to be a CFG splitting node.
1215 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1216 // should only have IfTrueNode and IfFalseNode (4985384).
1217 x_ctrl = find_non_split_ctrl(x_ctrl);
1218 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1219
1220 x->set_req(0, x_ctrl);
1221 }
1222 register_new_node(x, x_ctrl);
1223
1224 // Some institutional knowledge is needed here: 'x' is
1225 // yanked because if the optimizer runs GVN on it all the
1226 // cloned x's will common up and undo this optimization and
1227 // be forced back in the loop. This is annoying because it
1228 // makes +VerifyOpto report false-positives on progress. I
1229 // tried setting control edges on the x's to force them to
1230 // not combine, but the matching gets worried when it tries
1231 // to fold a StoreP and an AddP together (as part of an
1232 // address expression) and the AddP and StoreP have
1233 // different controls.
1234 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1235 }
1236 _igvn.remove_dead_node(n);
1237 }
1238 }
1239 }
1240 }
1241
1242 try_move_store_after_loop(n);
1243
1244 // Check for Opaque2's who's loop has disappeared - who's input is in the
1245 // same loop nest as their output. Remove 'em, they are no longer useful.
1246 if( n_op == Op_Opaque2 &&
1247 n->in(1) != NULL &&
1248 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1249 _igvn.replace_node( n, n->in(1) );
1250 }
1251 }
1252
1253 //------------------------------split_if_with_blocks---------------------------
1254 // Check for aggressive application of 'split-if' optimization,
1255 // using basic block level info.
1256 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1257 Node *n = C->root();
1258 visited.set(n->_idx); // first, mark node as visited
1259 // Do pre-visit work for root
1260 n = split_if_with_blocks_pre( n );
1261 uint cnt = n->outcnt();
1262 uint i = 0;
1263 while (true) {
1264 // Visit all children
1265 if (i < cnt) {
1266 Node* use = n->raw_out(i);
1267 ++i;
1268 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1269 // Now do pre-visit work for this use
1270 use = split_if_with_blocks_pre( use );
1271 nstack.push(n, i); // Save parent and next use's index.
1272 n = use; // Process all children of current use.
1273 cnt = use->outcnt();
1274 i = 0;
1275 }
1276 }
1277 else {
1278 // All of n's children have been processed, complete post-processing.
1279 if (cnt != 0 && !n->is_Con()) {
1280 assert(has_node(n), "no dead nodes");
1281 split_if_with_blocks_post( n );
1282 }
1283 if (nstack.is_empty()) {
1284 // Finished all nodes on stack.
1285 break;
1286 }
1287 // Get saved parent node and next use's index. Visit the rest of uses.
1288 n = nstack.node();
1289 cnt = n->outcnt();
1290 i = nstack.index();
1291 nstack.pop();
1292 }
1293 }
1294 }
1295
1296
1297 //=============================================================================
1298 //
1299 // C L O N E A L O O P B O D Y
1300 //
1301
1302 //------------------------------clone_iff--------------------------------------
1303 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1304 // "Nearly" because all Nodes have been cloned from the original in the loop,
1305 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1306 // through the Phi recursively, and return a Bool.
1307 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1308
1309 // Convert this Phi into a Phi merging Bools
1310 uint i;
1311 for( i = 1; i < phi->req(); i++ ) {
1312 Node *b = phi->in(i);
1313 if( b->is_Phi() ) {
1314 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1315 } else {
1316 assert( b->is_Bool(), "" );
1317 }
1318 }
1319
1320 Node *sample_bool = phi->in(1);
1321 Node *sample_cmp = sample_bool->in(1);
1322
1323 // Make Phis to merge the Cmp's inputs.
1324 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1325 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1326 for( i = 1; i < phi->req(); i++ ) {
1327 Node *n1 = phi->in(i)->in(1)->in(1);
1328 Node *n2 = phi->in(i)->in(1)->in(2);
1329 phi1->set_req( i, n1 );
1330 phi2->set_req( i, n2 );
1331 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1332 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1333 }
1334 // See if these Phis have been made before.
1335 // Register with optimizer
1336 Node *hit1 = _igvn.hash_find_insert(phi1);
1337 if( hit1 ) { // Hit, toss just made Phi
1338 _igvn.remove_dead_node(phi1); // Remove new phi
1339 assert( hit1->is_Phi(), "" );
1340 phi1 = (PhiNode*)hit1; // Use existing phi
1341 } else { // Miss
1342 _igvn.register_new_node_with_optimizer(phi1);
1343 }
1344 Node *hit2 = _igvn.hash_find_insert(phi2);
1345 if( hit2 ) { // Hit, toss just made Phi
1346 _igvn.remove_dead_node(phi2); // Remove new phi
1347 assert( hit2->is_Phi(), "" );
1348 phi2 = (PhiNode*)hit2; // Use existing phi
1349 } else { // Miss
1350 _igvn.register_new_node_with_optimizer(phi2);
1351 }
1352 // Register Phis with loop/block info
1353 set_ctrl(phi1, phi->in(0));
1354 set_ctrl(phi2, phi->in(0));
1355 // Make a new Cmp
1356 Node *cmp = sample_cmp->clone();
1357 cmp->set_req( 1, phi1 );
1358 cmp->set_req( 2, phi2 );
1359 _igvn.register_new_node_with_optimizer(cmp);
1360 set_ctrl(cmp, phi->in(0));
1361
1362 // Make a new Bool
1363 Node *b = sample_bool->clone();
1364 b->set_req(1,cmp);
1365 _igvn.register_new_node_with_optimizer(b);
1366 set_ctrl(b, phi->in(0));
1367
1368 assert( b->is_Bool(), "" );
1369 return (BoolNode*)b;
1370 }
1371
1372 //------------------------------clone_bool-------------------------------------
1373 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1374 // "Nearly" because all Nodes have been cloned from the original in the loop,
1375 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1376 // through the Phi recursively, and return a Bool.
1377 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1378 uint i;
1379 // Convert this Phi into a Phi merging Bools
1380 for( i = 1; i < phi->req(); i++ ) {
1381 Node *b = phi->in(i);
1382 if( b->is_Phi() ) {
1383 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1384 } else {
1385 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1386 }
1387 }
1388
1389 Node *sample_cmp = phi->in(1);
1390
1391 // Make Phis to merge the Cmp's inputs.
1392 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1393 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1394 for( uint j = 1; j < phi->req(); j++ ) {
1395 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1396 Node *n1, *n2;
1397 if( cmp_top->is_Cmp() ) {
1398 n1 = cmp_top->in(1);
1399 n2 = cmp_top->in(2);
1400 } else {
1401 n1 = n2 = cmp_top;
1402 }
1403 phi1->set_req( j, n1 );
1404 phi2->set_req( j, n2 );
1405 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1406 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1407 }
1408
1409 // See if these Phis have been made before.
1410 // Register with optimizer
1411 Node *hit1 = _igvn.hash_find_insert(phi1);
1412 if( hit1 ) { // Hit, toss just made Phi
1413 _igvn.remove_dead_node(phi1); // Remove new phi
1414 assert( hit1->is_Phi(), "" );
1415 phi1 = (PhiNode*)hit1; // Use existing phi
1416 } else { // Miss
1417 _igvn.register_new_node_with_optimizer(phi1);
1418 }
1419 Node *hit2 = _igvn.hash_find_insert(phi2);
1420 if( hit2 ) { // Hit, toss just made Phi
1421 _igvn.remove_dead_node(phi2); // Remove new phi
1422 assert( hit2->is_Phi(), "" );
1423 phi2 = (PhiNode*)hit2; // Use existing phi
1424 } else { // Miss
1425 _igvn.register_new_node_with_optimizer(phi2);
1426 }
1427 // Register Phis with loop/block info
1428 set_ctrl(phi1, phi->in(0));
1429 set_ctrl(phi2, phi->in(0));
1430 // Make a new Cmp
1431 Node *cmp = sample_cmp->clone();
1432 cmp->set_req( 1, phi1 );
1433 cmp->set_req( 2, phi2 );
1434 _igvn.register_new_node_with_optimizer(cmp);
1435 set_ctrl(cmp, phi->in(0));
1436
1437 assert( cmp->is_Cmp(), "" );
1438 return (CmpNode*)cmp;
1439 }
1440
1441 //------------------------------sink_use---------------------------------------
1442 // If 'use' was in the loop-exit block, it now needs to be sunk
1443 // below the post-loop merge point.
1444 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1445 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1446 set_ctrl(use, post_loop);
1447 for (DUIterator j = use->outs(); use->has_out(j); j++)
1448 sink_use(use->out(j), post_loop);
1449 }
1450 }
1451
1452 //------------------------------clone_loop-------------------------------------
1453 //
1454 // C L O N E A L O O P B O D Y
1455 //
1456 // This is the basic building block of the loop optimizations. It clones an
1457 // entire loop body. It makes an old_new loop body mapping; with this mapping
1458 // you can find the new-loop equivalent to an old-loop node. All new-loop
1459 // nodes are exactly equal to their old-loop counterparts, all edges are the
1460 // same. All exits from the old-loop now have a RegionNode that merges the
1461 // equivalent new-loop path. This is true even for the normal "loop-exit"
1462 // condition. All uses of loop-invariant old-loop values now come from (one
1463 // or more) Phis that merge their new-loop equivalents.
1464 //
1465 // This operation leaves the graph in an illegal state: there are two valid
1466 // control edges coming from the loop pre-header to both loop bodies. I'll
1467 // definitely have to hack the graph after running this transform.
1468 //
1469 // From this building block I will further edit edges to perform loop peeling
1470 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1471 //
1472 // Parameter side_by_size_idom:
1473 // When side_by_size_idom is NULL, the dominator tree is constructed for
1474 // the clone loop to dominate the original. Used in construction of
1475 // pre-main-post loop sequence.
1476 // When nonnull, the clone and original are side-by-side, both are
1477 // dominated by the side_by_side_idom node. Used in construction of
1478 // unswitched loops.
1479 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1480 Node* side_by_side_idom) {
1481
1482 #ifndef PRODUCT
1483 if (C->do_vector_loop() && PrintOpto) {
1484 const char* mname = C->method()->name()->as_quoted_ascii();
1485 if (mname != NULL) {
1486 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1487 }
1488 }
1489 #endif
1490
1491 CloneMap& cm = C->clone_map();
1492 Dict* dict = cm.dict();
1493 if (C->do_vector_loop()) {
1494 cm.set_clone_idx(cm.max_gen()+1);
1495 #ifndef PRODUCT
1496 if (PrintOpto) {
1497 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1498 loop->dump_head();
1499 }
1500 #endif
1501 }
1502
1503 // Step 1: Clone the loop body. Make the old->new mapping.
1504 uint i;
1505 for( i = 0; i < loop->_body.size(); i++ ) {
1506 Node *old = loop->_body.at(i);
1507 Node *nnn = old->clone();
1508 old_new.map( old->_idx, nnn );
1509 if (C->do_vector_loop()) {
1510 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1511 }
1512 _igvn.register_new_node_with_optimizer(nnn);
1513 }
1514
1515
1516 // Step 2: Fix the edges in the new body. If the old input is outside the
1517 // loop use it. If the old input is INside the loop, use the corresponding
1518 // new node instead.
1519 for( i = 0; i < loop->_body.size(); i++ ) {
1520 Node *old = loop->_body.at(i);
1521 Node *nnn = old_new[old->_idx];
1522 // Fix CFG/Loop controlling the new node
1523 if (has_ctrl(old)) {
1524 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1525 } else {
1526 set_loop(nnn, loop->_parent);
1527 if (old->outcnt() > 0) {
1528 set_idom( nnn, old_new[idom(old)->_idx], dd );
1529 }
1530 }
1531 // Correct edges to the new node
1532 for( uint j = 0; j < nnn->req(); j++ ) {
1533 Node *n = nnn->in(j);
1534 if( n ) {
1535 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1536 if( loop->is_member( old_in_loop ) )
1537 nnn->set_req(j, old_new[n->_idx]);
1538 }
1539 }
1540 _igvn.hash_find_insert(nnn);
1541 }
1542 Node *newhead = old_new[loop->_head->_idx];
1543 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1544
1545
1546 // Step 3: Now fix control uses. Loop varying control uses have already
1547 // been fixed up (as part of all input edges in Step 2). Loop invariant
1548 // control uses must be either an IfFalse or an IfTrue. Make a merge
1549 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1550 // refer to this.
1551 ResourceArea *area = Thread::current()->resource_area();
1552 Node_List worklist(area);
1553 uint new_counter = C->unique();
1554 for( i = 0; i < loop->_body.size(); i++ ) {
1555 Node* old = loop->_body.at(i);
1556 if( !old->is_CFG() ) continue;
1557 Node* nnn = old_new[old->_idx];
1558
1559 // Copy uses to a worklist, so I can munge the def-use info
1560 // with impunity.
1561 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1562 worklist.push(old->fast_out(j));
1563
1564 while( worklist.size() ) { // Visit all uses
1565 Node *use = worklist.pop();
1566 if (!has_node(use)) continue; // Ignore dead nodes
1567 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1568 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1569 // Both OLD and USE are CFG nodes here.
1570 assert( use->is_Proj(), "" );
1571
1572 // Clone the loop exit control projection
1573 Node *newuse = use->clone();
1574 if (C->do_vector_loop()) {
1575 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1576 }
1577 newuse->set_req(0,nnn);
1578 _igvn.register_new_node_with_optimizer(newuse);
1579 set_loop(newuse, use_loop);
1580 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1581
1582 // We need a Region to merge the exit from the peeled body and the
1583 // exit from the old loop body.
1584 RegionNode *r = new RegionNode(3);
1585 // Map the old use to the new merge point
1586 old_new.map( use->_idx, r );
1587 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1588 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1589
1590 // The original user of 'use' uses 'r' instead.
1591 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1592 Node* useuse = use->last_out(l);
1593 _igvn.rehash_node_delayed(useuse);
1594 uint uses_found = 0;
1595 if( useuse->in(0) == use ) {
1596 useuse->set_req(0, r);
1597 uses_found++;
1598 if( useuse->is_CFG() ) {
1599 assert( dom_depth(useuse) > dd_r, "" );
1600 set_idom(useuse, r, dom_depth(useuse));
1601 }
1602 }
1603 for( uint k = 1; k < useuse->req(); k++ ) {
1604 if( useuse->in(k) == use ) {
1605 useuse->set_req(k, r);
1606 uses_found++;
1607 }
1608 }
1609 l -= uses_found; // we deleted 1 or more copies of this edge
1610 }
1611
1612 // Now finish up 'r'
1613 r->set_req( 1, newuse );
1614 r->set_req( 2, use );
1615 _igvn.register_new_node_with_optimizer(r);
1616 set_loop(r, use_loop);
1617 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1618 } // End of if a loop-exit test
1619 }
1620 }
1621
1622 // Step 4: If loop-invariant use is not control, it must be dominated by a
1623 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1624 // there if needed. Make a Phi there merging old and new used values.
1625 Node_List *split_if_set = NULL;
1626 Node_List *split_bool_set = NULL;
1627 Node_List *split_cex_set = NULL;
1628 for( i = 0; i < loop->_body.size(); i++ ) {
1629 Node* old = loop->_body.at(i);
1630 Node* nnn = old_new[old->_idx];
1631 // Copy uses to a worklist, so I can munge the def-use info
1632 // with impunity.
1633 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1634 worklist.push(old->fast_out(j));
1635
1636 while( worklist.size() ) {
1637 Node *use = worklist.pop();
1638 if (!has_node(use)) continue; // Ignore dead nodes
1639 if (use->in(0) == C->top()) continue;
1640 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1641 // Check for data-use outside of loop - at least one of OLD or USE
1642 // must not be a CFG node.
1643 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1644
1645 // If the Data use is an IF, that means we have an IF outside of the
1646 // loop that is switching on a condition that is set inside of the
1647 // loop. Happens if people set a loop-exit flag; then test the flag
1648 // in the loop to break the loop, then test is again outside of the
1649 // loop to determine which way the loop exited.
1650 // Loop predicate If node connects to Bool node through Opaque1 node.
1651 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1652 // Since this code is highly unlikely, we lazily build the worklist
1653 // of such Nodes to go split.
1654 if( !split_if_set )
1655 split_if_set = new Node_List(area);
1656 split_if_set->push(use);
1657 }
1658 if( use->is_Bool() ) {
1659 if( !split_bool_set )
1660 split_bool_set = new Node_List(area);
1661 split_bool_set->push(use);
1662 }
1663 if( use->Opcode() == Op_CreateEx ) {
1664 if( !split_cex_set )
1665 split_cex_set = new Node_List(area);
1666 split_cex_set->push(use);
1667 }
1668
1669
1670 // Get "block" use is in
1671 uint idx = 0;
1672 while( use->in(idx) != old ) idx++;
1673 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1674 assert( !loop->is_member( get_loop( prev ) ), "" );
1675 Node *cfg = prev->_idx >= new_counter
1676 ? prev->in(2)
1677 : idom(prev);
1678 if( use->is_Phi() ) // Phi use is in prior block
1679 cfg = prev->in(idx); // NOT in block of Phi itself
1680 if (cfg->is_top()) { // Use is dead?
1681 _igvn.replace_input_of(use, idx, C->top());
1682 continue;
1683 }
1684
1685 while( !loop->is_member( get_loop( cfg ) ) ) {
1686 prev = cfg;
1687 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1688 }
1689 // If the use occurs after merging several exits from the loop, then
1690 // old value must have dominated all those exits. Since the same old
1691 // value was used on all those exits we did not need a Phi at this
1692 // merge point. NOW we do need a Phi here. Each loop exit value
1693 // is now merged with the peeled body exit; each exit gets its own
1694 // private Phi and those Phis need to be merged here.
1695 Node *phi;
1696 if( prev->is_Region() ) {
1697 if( idx == 0 ) { // Updating control edge?
1698 phi = prev; // Just use existing control
1699 } else { // Else need a new Phi
1700 phi = PhiNode::make( prev, old );
1701 // Now recursively fix up the new uses of old!
1702 for( uint i = 1; i < prev->req(); i++ ) {
1703 worklist.push(phi); // Onto worklist once for each 'old' input
1704 }
1705 }
1706 } else {
1707 // Get new RegionNode merging old and new loop exits
1708 prev = old_new[prev->_idx];
1709 assert( prev, "just made this in step 7" );
1710 if( idx == 0 ) { // Updating control edge?
1711 phi = prev; // Just use existing control
1712 } else { // Else need a new Phi
1713 // Make a new Phi merging data values properly
1714 phi = PhiNode::make( prev, old );
1715 phi->set_req( 1, nnn );
1716 }
1717 }
1718 // If inserting a new Phi, check for prior hits
1719 if( idx != 0 ) {
1720 Node *hit = _igvn.hash_find_insert(phi);
1721 if( hit == NULL ) {
1722 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1723 } else { // or
1724 // Remove the new phi from the graph and use the hit
1725 _igvn.remove_dead_node(phi);
1726 phi = hit; // Use existing phi
1727 }
1728 set_ctrl(phi, prev);
1729 }
1730 // Make 'use' use the Phi instead of the old loop body exit value
1731 _igvn.replace_input_of(use, idx, phi);
1732 if( use->_idx >= new_counter ) { // If updating new phis
1733 // Not needed for correctness, but prevents a weak assert
1734 // in AddPNode from tripping (when we end up with different
1735 // base & derived Phis that will become the same after
1736 // IGVN does CSE).
1737 Node *hit = _igvn.hash_find_insert(use);
1738 if( hit ) // Go ahead and re-hash for hits.
1739 _igvn.replace_node( use, hit );
1740 }
1741
1742 // If 'use' was in the loop-exit block, it now needs to be sunk
1743 // below the post-loop merge point.
1744 sink_use( use, prev );
1745 }
1746 }
1747 }
1748
1749 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1750 // the loop uses a condition set in the loop. The original IF probably
1751 // takes control from one or more OLD Regions (which in turn get from NEW
1752 // Regions). In any case, there will be a set of Phis for each merge point
1753 // from the IF up to where the original BOOL def exists the loop.
1754 if( split_if_set ) {
1755 while( split_if_set->size() ) {
1756 Node *iff = split_if_set->pop();
1757 if( iff->in(1)->is_Phi() ) {
1758 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1759 _igvn.replace_input_of(iff, 1, b);
1760 }
1761 }
1762 }
1763 if( split_bool_set ) {
1764 while( split_bool_set->size() ) {
1765 Node *b = split_bool_set->pop();
1766 Node *phi = b->in(1);
1767 assert( phi->is_Phi(), "" );
1768 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1769 _igvn.replace_input_of(b, 1, cmp);
1770 }
1771 }
1772 if( split_cex_set ) {
1773 while( split_cex_set->size() ) {
1774 Node *b = split_cex_set->pop();
1775 assert( b->in(0)->is_Region(), "" );
1776 assert( b->in(1)->is_Phi(), "" );
1777 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1778 split_up( b, b->in(0), NULL );
1779 }
1780 }
1781
1782 }
1783
1784
1785 //---------------------- stride_of_possible_iv -------------------------------------
1786 // Looks for an iff/bool/comp with one operand of the compare
1787 // being a cycle involving an add and a phi,
1788 // with an optional truncation (left-shift followed by a right-shift)
1789 // of the add. Returns zero if not an iv.
1790 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1791 Node* trunc1 = NULL;
1792 Node* trunc2 = NULL;
1793 const TypeInt* ttype = NULL;
1794 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1795 return 0;
1796 }
1797 BoolNode* bl = iff->in(1)->as_Bool();
1798 Node* cmp = bl->in(1);
1799 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1800 return 0;
1801 }
1802 // Must have an invariant operand
1803 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1804 return 0;
1805 }
1806 Node* add2 = NULL;
1807 Node* cmp1 = cmp->in(1);
1808 if (cmp1->is_Phi()) {
1809 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1810 Node* phi = cmp1;
1811 for (uint i = 1; i < phi->req(); i++) {
1812 Node* in = phi->in(i);
1813 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1814 &trunc1, &trunc2, &ttype);
1815 if (add && add->in(1) == phi) {
1816 add2 = add->in(2);
1817 break;
1818 }
1819 }
1820 } else {
1821 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1822 Node* addtrunc = cmp1;
1823 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1824 &trunc1, &trunc2, &ttype);
1825 if (add && add->in(1)->is_Phi()) {
1826 Node* phi = add->in(1);
1827 for (uint i = 1; i < phi->req(); i++) {
1828 if (phi->in(i) == addtrunc) {
1829 add2 = add->in(2);
1830 break;
1831 }
1832 }
1833 }
1834 }
1835 if (add2 != NULL) {
1836 const TypeInt* add2t = _igvn.type(add2)->is_int();
1837 if (add2t->is_con()) {
1838 return add2t->get_con();
1839 }
1840 }
1841 return 0;
1842 }
1843
1844
1845 //---------------------- stay_in_loop -------------------------------------
1846 // Return the (unique) control output node that's in the loop (if it exists.)
1847 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1848 Node* unique = NULL;
1849 if (!n) return NULL;
1850 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1851 Node* use = n->fast_out(i);
1852 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1853 if (unique != NULL) {
1854 return NULL;
1855 }
1856 unique = use;
1857 }
1858 }
1859 return unique;
1860 }
1861
1862 //------------------------------ register_node -------------------------------------
1863 // Utility to register node "n" with PhaseIdealLoop
1864 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1865 _igvn.register_new_node_with_optimizer(n);
1866 loop->_body.push(n);
1867 if (n->is_CFG()) {
1868 set_loop(n, loop);
1869 set_idom(n, pred, ddepth);
1870 } else {
1871 set_ctrl(n, pred);
1872 }
1873 }
1874
1875 //------------------------------ proj_clone -------------------------------------
1876 // Utility to create an if-projection
1877 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1878 ProjNode* c = p->clone()->as_Proj();
1879 c->set_req(0, iff);
1880 return c;
1881 }
1882
1883 //------------------------------ short_circuit_if -------------------------------------
1884 // Force the iff control output to be the live_proj
1885 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1886 guarantee(live_proj != NULL, "null projection");
1887 int proj_con = live_proj->_con;
1888 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1889 Node *con = _igvn.intcon(proj_con);
1890 set_ctrl(con, C->root());
1891 if (iff) {
1892 iff->set_req(1, con);
1893 }
1894 return con;
1895 }
1896
1897 //------------------------------ insert_if_before_proj -------------------------------------
1898 // Insert a new if before an if projection (* - new node)
1899 //
1900 // before
1901 // if(test)
1902 // / \
1903 // v v
1904 // other-proj proj (arg)
1905 //
1906 // after
1907 // if(test)
1908 // / \
1909 // / v
1910 // | * proj-clone
1911 // v |
1912 // other-proj v
1913 // * new_if(relop(cmp[IU](left,right)))
1914 // / \
1915 // v v
1916 // * new-proj proj
1917 // (returned)
1918 //
1919 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1920 IfNode* iff = proj->in(0)->as_If();
1921 IdealLoopTree *loop = get_loop(proj);
1922 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1923 int ddepth = dom_depth(proj);
1924
1925 _igvn.rehash_node_delayed(iff);
1926 _igvn.rehash_node_delayed(proj);
1927
1928 proj->set_req(0, NULL); // temporary disconnect
1929 ProjNode* proj2 = proj_clone(proj, iff);
1930 register_node(proj2, loop, iff, ddepth);
1931
1932 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1933 register_node(cmp, loop, proj2, ddepth);
1934
1935 BoolNode* bol = new BoolNode(cmp, relop);
1936 register_node(bol, loop, proj2, ddepth);
1937
1938 IfNode* new_if = new IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1939 register_node(new_if, loop, proj2, ddepth);
1940
1941 proj->set_req(0, new_if); // reattach
1942 set_idom(proj, new_if, ddepth);
1943
1944 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1945 guarantee(new_exit != NULL, "null exit node");
1946 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1947
1948 return new_exit;
1949 }
1950
1951 //------------------------------ insert_region_before_proj -------------------------------------
1952 // Insert a region before an if projection (* - new node)
1953 //
1954 // before
1955 // if(test)
1956 // / |
1957 // v |
1958 // proj v
1959 // other-proj
1960 //
1961 // after
1962 // if(test)
1963 // / |
1964 // v |
1965 // * proj-clone v
1966 // | other-proj
1967 // v
1968 // * new-region
1969 // |
1970 // v
1971 // * dum_if
1972 // / \
1973 // v \
1974 // * dum-proj v
1975 // proj
1976 //
1977 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1978 IfNode* iff = proj->in(0)->as_If();
1979 IdealLoopTree *loop = get_loop(proj);
1980 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1981 int ddepth = dom_depth(proj);
1982
1983 _igvn.rehash_node_delayed(iff);
1984 _igvn.rehash_node_delayed(proj);
1985
1986 proj->set_req(0, NULL); // temporary disconnect
1987 ProjNode* proj2 = proj_clone(proj, iff);
1988 register_node(proj2, loop, iff, ddepth);
1989
1990 RegionNode* reg = new RegionNode(2);
1991 reg->set_req(1, proj2);
1992 register_node(reg, loop, iff, ddepth);
1993
1994 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
1995 register_node(dum_if, loop, reg, ddepth);
1996
1997 proj->set_req(0, dum_if); // reattach
1998 set_idom(proj, dum_if, ddepth);
1999
2000 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2001 register_node(dum_proj, loop, dum_if, ddepth);
2002
2003 return reg;
2004 }
2005
2006 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2007 // Clone a signed compare loop exit from an unsigned compare and
2008 // insert it before the unsigned cmp on the stay-in-loop path.
2009 // All new nodes inserted in the dominator tree between the original
2010 // if and it's projections. The original if test is replaced with
2011 // a constant to force the stay-in-loop path.
2012 //
2013 // This is done to make sure that the original if and it's projections
2014 // still dominate the same set of control nodes, that the ctrl() relation
2015 // from data nodes to them is preserved, and that their loop nesting is
2016 // preserved.
2017 //
2018 // before
2019 // if(i <u limit) unsigned compare loop exit
2020 // / |
2021 // v v
2022 // exit-proj stay-in-loop-proj
2023 //
2024 // after
2025 // if(stay-in-loop-const) original if
2026 // / |
2027 // / v
2028 // / if(i < limit) new signed test
2029 // / / |
2030 // / / v
2031 // / / if(i <u limit) new cloned unsigned test
2032 // / / / |
2033 // v v v |
2034 // region |
2035 // | |
2036 // dum-if |
2037 // / | |
2038 // ether | |
2039 // v v
2040 // exit-proj stay-in-loop-proj
2041 //
2042 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2043 const bool Signed = true;
2044 const bool Unsigned = false;
2045
2046 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2047 if (bol->_test._test != BoolTest::lt) return NULL;
2048 CmpNode* cmpu = bol->in(1)->as_Cmp();
2049 if (cmpu->Opcode() != Op_CmpU) return NULL;
2050 int stride = stride_of_possible_iv(if_cmpu);
2051 if (stride == 0) return NULL;
2052
2053 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2054 guarantee(lp_proj != NULL, "null loop node");
2055
2056 ProjNode* lp_continue = lp_proj->as_Proj();
2057 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2058
2059 Node* limit = NULL;
2060 if (stride > 0) {
2061 limit = cmpu->in(2);
2062 } else {
2063 limit = _igvn.makecon(TypeInt::ZERO);
2064 set_ctrl(limit, C->root());
2065 }
2066 // Create a new region on the exit path
2067 RegionNode* reg = insert_region_before_proj(lp_exit);
2068 guarantee(reg != NULL, "null region node");
2069
2070 // Clone the if-cmpu-true-false using a signed compare
2071 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2072 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2073 reg->add_req(cmpi_exit);
2074
2075 // Clone the if-cmpu-true-false
2076 BoolTest::mask rel_u = bol->_test._test;
2077 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2078 reg->add_req(cmpu_exit);
2079
2080 // Force original if to stay in loop.
2081 short_circuit_if(if_cmpu, lp_continue);
2082
2083 return cmpi_exit->in(0)->as_If();
2084 }
2085
2086 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2087 // Remove a previously inserted signed compare loop exit.
2088 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2089 Node* lp_proj = stay_in_loop(if_cmp, loop);
2090 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2091 stay_in_loop(lp_proj, loop)->is_If() &&
2092 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2093 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2094 set_ctrl(con, C->root());
2095 if_cmp->set_req(1, con);
2096 }
2097
2098 //------------------------------ scheduled_nodelist -------------------------------------
2099 // Create a post order schedule of nodes that are in the
2100 // "member" set. The list is returned in "sched".
2101 // The first node in "sched" is the loop head, followed by
2102 // nodes which have no inputs in the "member" set, and then
2103 // followed by the nodes that have an immediate input dependence
2104 // on a node in "sched".
2105 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2106
2107 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2108 Arena *a = Thread::current()->resource_area();
2109 VectorSet visited(a);
2110 Node_Stack nstack(a, loop->_body.size());
2111
2112 Node* n = loop->_head; // top of stack is cached in "n"
2113 uint idx = 0;
2114 visited.set(n->_idx);
2115
2116 // Initially push all with no inputs from within member set
2117 for(uint i = 0; i < loop->_body.size(); i++ ) {
2118 Node *elt = loop->_body.at(i);
2119 if (member.test(elt->_idx)) {
2120 bool found = false;
2121 for (uint j = 0; j < elt->req(); j++) {
2122 Node* def = elt->in(j);
2123 if (def && member.test(def->_idx) && def != elt) {
2124 found = true;
2125 break;
2126 }
2127 }
2128 if (!found && elt != loop->_head) {
2129 nstack.push(n, idx);
2130 n = elt;
2131 assert(!visited.test(n->_idx), "not seen yet");
2132 visited.set(n->_idx);
2133 }
2134 }
2135 }
2136
2137 // traverse out's that are in the member set
2138 while (true) {
2139 if (idx < n->outcnt()) {
2140 Node* use = n->raw_out(idx);
2141 idx++;
2142 if (!visited.test_set(use->_idx)) {
2143 if (member.test(use->_idx)) {
2144 nstack.push(n, idx);
2145 n = use;
2146 idx = 0;
2147 }
2148 }
2149 } else {
2150 // All outputs processed
2151 sched.push(n);
2152 if (nstack.is_empty()) break;
2153 n = nstack.node();
2154 idx = nstack.index();
2155 nstack.pop();
2156 }
2157 }
2158 }
2159
2160
2161 //------------------------------ has_use_in_set -------------------------------------
2162 // Has a use in the vector set
2163 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2164 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2165 Node* use = n->fast_out(j);
2166 if (vset.test(use->_idx)) {
2167 return true;
2168 }
2169 }
2170 return false;
2171 }
2172
2173
2174 //------------------------------ has_use_internal_to_set -------------------------------------
2175 // Has use internal to the vector set (ie. not in a phi at the loop head)
2176 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2177 Node* head = loop->_head;
2178 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2179 Node* use = n->fast_out(j);
2180 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2181 return true;
2182 }
2183 }
2184 return false;
2185 }
2186
2187
2188 //------------------------------ clone_for_use_outside_loop -------------------------------------
2189 // clone "n" for uses that are outside of loop
2190 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2191 int cloned = 0;
2192 assert(worklist.size() == 0, "should be empty");
2193 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2194 Node* use = n->fast_out(j);
2195 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2196 worklist.push(use);
2197 }
2198 }
2199 while( worklist.size() ) {
2200 Node *use = worklist.pop();
2201 if (!has_node(use) || use->in(0) == C->top()) continue;
2202 uint j;
2203 for (j = 0; j < use->req(); j++) {
2204 if (use->in(j) == n) break;
2205 }
2206 assert(j < use->req(), "must be there");
2207
2208 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2209 Node* n_clone = n->clone();
2210 _igvn.replace_input_of(use, j, n_clone);
2211 cloned++;
2212 Node* use_c;
2213 if (!use->is_Phi()) {
2214 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2215 } else {
2216 // Use in a phi is considered a use in the associated predecessor block
2217 use_c = use->in(0)->in(j);
2218 }
2219 set_ctrl(n_clone, use_c);
2220 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2221 get_loop(use_c)->_body.push(n_clone);
2222 _igvn.register_new_node_with_optimizer(n_clone);
2223 #if !defined(PRODUCT)
2224 if (TracePartialPeeling) {
2225 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2226 }
2227 #endif
2228 }
2229 return cloned;
2230 }
2231
2232
2233 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2234 // clone "n" for special uses that are in the not_peeled region.
2235 // If these def-uses occur in separate blocks, the code generator
2236 // marks the method as not compilable. For example, if a "BoolNode"
2237 // is in a different basic block than the "IfNode" that uses it, then
2238 // the compilation is aborted in the code generator.
2239 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2240 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2241 if (n->is_Phi() || n->is_Load()) {
2242 return;
2243 }
2244 assert(worklist.size() == 0, "should be empty");
2245 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2246 Node* use = n->fast_out(j);
2247 if ( not_peel.test(use->_idx) &&
2248 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2249 use->in(1) == n) {
2250 worklist.push(use);
2251 }
2252 }
2253 if (worklist.size() > 0) {
2254 // clone "n" and insert it between inputs of "n" and the use
2255 Node* n_clone = n->clone();
2256 loop->_body.push(n_clone);
2257 _igvn.register_new_node_with_optimizer(n_clone);
2258 set_ctrl(n_clone, get_ctrl(n));
2259 sink_list.push(n_clone);
2260 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2261 #if !defined(PRODUCT)
2262 if (TracePartialPeeling) {
2263 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2264 }
2265 #endif
2266 while( worklist.size() ) {
2267 Node *use = worklist.pop();
2268 _igvn.rehash_node_delayed(use);
2269 for (uint j = 1; j < use->req(); j++) {
2270 if (use->in(j) == n) {
2271 use->set_req(j, n_clone);
2272 }
2273 }
2274 }
2275 }
2276 }
2277
2278
2279 //------------------------------ insert_phi_for_loop -------------------------------------
2280 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2281 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2282 Node *phi = PhiNode::make(lp, back_edge_val);
2283 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2284 // Use existing phi if it already exists
2285 Node *hit = _igvn.hash_find_insert(phi);
2286 if( hit == NULL ) {
2287 _igvn.register_new_node_with_optimizer(phi);
2288 set_ctrl(phi, lp);
2289 } else {
2290 // Remove the new phi from the graph and use the hit
2291 _igvn.remove_dead_node(phi);
2292 phi = hit;
2293 }
2294 _igvn.replace_input_of(use, idx, phi);
2295 }
2296
2297 #ifdef ASSERT
2298 //------------------------------ is_valid_loop_partition -------------------------------------
2299 // Validate the loop partition sets: peel and not_peel
2300 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2301 VectorSet& not_peel ) {
2302 uint i;
2303 // Check that peel_list entries are in the peel set
2304 for (i = 0; i < peel_list.size(); i++) {
2305 if (!peel.test(peel_list.at(i)->_idx)) {
2306 return false;
2307 }
2308 }
2309 // Check at loop members are in one of peel set or not_peel set
2310 for (i = 0; i < loop->_body.size(); i++ ) {
2311 Node *def = loop->_body.at(i);
2312 uint di = def->_idx;
2313 // Check that peel set elements are in peel_list
2314 if (peel.test(di)) {
2315 if (not_peel.test(di)) {
2316 return false;
2317 }
2318 // Must be in peel_list also
2319 bool found = false;
2320 for (uint j = 0; j < peel_list.size(); j++) {
2321 if (peel_list.at(j)->_idx == di) {
2322 found = true;
2323 break;
2324 }
2325 }
2326 if (!found) {
2327 return false;
2328 }
2329 } else if (not_peel.test(di)) {
2330 if (peel.test(di)) {
2331 return false;
2332 }
2333 } else {
2334 return false;
2335 }
2336 }
2337 return true;
2338 }
2339
2340 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2341 // Ensure a use outside of loop is of the right form
2342 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2343 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2344 return (use->is_Phi() &&
2345 use_c->is_Region() && use_c->req() == 3 &&
2346 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2347 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2348 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2349 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2350 }
2351
2352 //------------------------------ is_valid_clone_loop_form -------------------------------------
2353 // Ensure that all uses outside of loop are of the right form
2354 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2355 uint orig_exit_idx, uint clone_exit_idx) {
2356 uint len = peel_list.size();
2357 for (uint i = 0; i < len; i++) {
2358 Node *def = peel_list.at(i);
2359
2360 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2361 Node *use = def->fast_out(j);
2362 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2363 if (!loop->is_member(get_loop(use_c))) {
2364 // use is not in the loop, check for correct structure
2365 if (use->in(0) == def) {
2366 // Okay
2367 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2368 return false;
2369 }
2370 }
2371 }
2372 }
2373 return true;
2374 }
2375 #endif
2376
2377 //------------------------------ partial_peel -------------------------------------
2378 // Partially peel (aka loop rotation) the top portion of a loop (called
2379 // the peel section below) by cloning it and placing one copy just before
2380 // the new loop head and the other copy at the bottom of the new loop.
2381 //
2382 // before after where it came from
2383 //
2384 // stmt1 stmt1
2385 // loop: stmt2 clone
2386 // stmt2 if condA goto exitA clone
2387 // if condA goto exitA new_loop: new
2388 // stmt3 stmt3 clone
2389 // if !condB goto loop if condB goto exitB clone
2390 // exitB: stmt2 orig
2391 // stmt4 if !condA goto new_loop orig
2392 // exitA: goto exitA
2393 // exitB:
2394 // stmt4
2395 // exitA:
2396 //
2397 // Step 1: find the cut point: an exit test on probable
2398 // induction variable.
2399 // Step 2: schedule (with cloning) operations in the peel
2400 // section that can be executed after the cut into
2401 // the section that is not peeled. This may need
2402 // to clone operations into exit blocks. For
2403 // instance, a reference to A[i] in the not-peel
2404 // section and a reference to B[i] in an exit block
2405 // may cause a left-shift of i by 2 to be placed
2406 // in the peel block. This step will clone the left
2407 // shift into the exit block and sink the left shift
2408 // from the peel to the not-peel section.
2409 // Step 3: clone the loop, retarget the control, and insert
2410 // phis for values that are live across the new loop
2411 // head. This is very dependent on the graph structure
2412 // from clone_loop. It creates region nodes for
2413 // exit control and associated phi nodes for values
2414 // flow out of the loop through that exit. The region
2415 // node is dominated by the clone's control projection.
2416 // So the clone's peel section is placed before the
2417 // new loop head, and the clone's not-peel section is
2418 // forms the top part of the new loop. The original
2419 // peel section forms the tail of the new loop.
2420 // Step 4: update the dominator tree and recompute the
2421 // dominator depth.
2422 //
2423 // orig
2424 //
2425 // stmt1
2426 // |
2427 // v
2428 // loop predicate
2429 // |
2430 // v
2431 // loop<----+
2432 // | |
2433 // stmt2 |
2434 // | |
2435 // v |
2436 // ifA |
2437 // / | |
2438 // v v |
2439 // false true ^ <-- last_peel
2440 // / | |
2441 // / ===|==cut |
2442 // / stmt3 | <-- first_not_peel
2443 // / | |
2444 // | v |
2445 // v ifB |
2446 // exitA: / \ |
2447 // / \ |
2448 // v v |
2449 // false true |
2450 // / \ |
2451 // / ----+
2452 // |
2453 // v
2454 // exitB:
2455 // stmt4
2456 //
2457 //
2458 // after clone loop
2459 //
2460 // stmt1
2461 // |
2462 // v
2463 // loop predicate
2464 // / \
2465 // clone / \ orig
2466 // / \
2467 // / \
2468 // v v
2469 // +---->loop loop<----+
2470 // | | | |
2471 // | stmt2 stmt2 |
2472 // | | | |
2473 // | v v |
2474 // | ifA ifA |
2475 // | | \ / | |
2476 // | v v v v |
2477 // ^ true false false true ^ <-- last_peel
2478 // | | ^ \ / | |
2479 // | cut==|== \ \ / ===|==cut |
2480 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2481 // | | dom | | | |
2482 // | v \ 1v v2 v |
2483 // | ifB regionA ifB |
2484 // | / \ | / \ |
2485 // | / \ v / \ |
2486 // | v v exitA: v v |
2487 // | true false false true |
2488 // | / ^ \ / \ |
2489 // +---- \ \ / ----+
2490 // dom \ /
2491 // \ 1v v2
2492 // regionB
2493 // |
2494 // v
2495 // exitB:
2496 // stmt4
2497 //
2498 //
2499 // after partial peel
2500 //
2501 // stmt1
2502 // |
2503 // v
2504 // loop predicate
2505 // /
2506 // clone / orig
2507 // / TOP
2508 // / \
2509 // v v
2510 // TOP->loop loop----+
2511 // | | |
2512 // stmt2 stmt2 |
2513 // | | |
2514 // v v |
2515 // ifA ifA |
2516 // | \ / | |
2517 // v v v v |
2518 // true false false true | <-- last_peel
2519 // | ^ \ / +------|---+
2520 // +->newloop \ \ / === ==cut | |
2521 // | stmt3 \ \ / TOP | |
2522 // | | dom | | stmt3 | | <-- first_not_peel
2523 // | v \ 1v v2 v | |
2524 // | ifB regionA ifB ^ v
2525 // | / \ | / \ | |
2526 // | / \ v / \ | |
2527 // | v v exitA: v v | |
2528 // | true false false true | |
2529 // | / ^ \ / \ | |
2530 // | | \ \ / v | |
2531 // | | dom \ / TOP | |
2532 // | | \ 1v v2 | |
2533 // ^ v regionB | |
2534 // | | | | |
2535 // | | v ^ v
2536 // | | exitB: | |
2537 // | | stmt4 | |
2538 // | +------------>-----------------+ |
2539 // | |
2540 // +-----------------<---------------------+
2541 //
2542 //
2543 // final graph
2544 //
2545 // stmt1
2546 // |
2547 // v
2548 // loop predicate
2549 // |
2550 // v
2551 // stmt2 clone
2552 // |
2553 // v
2554 // ........> ifA clone
2555 // : / |
2556 // dom / |
2557 // : v v
2558 // : false true
2559 // : | |
2560 // : | v
2561 // : | newloop<-----+
2562 // : | | |
2563 // : | stmt3 clone |
2564 // : | | |
2565 // : | v |
2566 // : | ifB |
2567 // : | / \ |
2568 // : | v v |
2569 // : | false true |
2570 // : | | | |
2571 // : | v stmt2 |
2572 // : | exitB: | |
2573 // : | stmt4 v |
2574 // : | ifA orig |
2575 // : | / \ |
2576 // : | / \ |
2577 // : | v v |
2578 // : | false true |
2579 // : | / \ |
2580 // : v v -----+
2581 // RegionA
2582 // |
2583 // v
2584 // exitA
2585 //
2586 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2587
2588 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2589 if (!loop->_head->is_Loop()) {
2590 return false; }
2591
2592 LoopNode *head = loop->_head->as_Loop();
2593
2594 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2595 return false;
2596 }
2597
2598 // Check for complex exit control
2599 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2600 Node *n = loop->_body.at(ii);
2601 int opc = n->Opcode();
2602 if (n->is_Call() ||
2603 opc == Op_Catch ||
2604 opc == Op_CatchProj ||
2605 opc == Op_Jump ||
2606 opc == Op_JumpProj) {
2607 #if !defined(PRODUCT)
2608 if (TracePartialPeeling) {
2609 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2610 }
2611 #endif
2612 return false;
2613 }
2614 }
2615
2616 int dd = dom_depth(head);
2617
2618 // Step 1: find cut point
2619
2620 // Walk up dominators to loop head looking for first loop exit
2621 // which is executed on every path thru loop.
2622 IfNode *peel_if = NULL;
2623 IfNode *peel_if_cmpu = NULL;
2624
2625 Node *iff = loop->tail();
2626 while( iff != head ) {
2627 if( iff->is_If() ) {
2628 Node *ctrl = get_ctrl(iff->in(1));
2629 if (ctrl->is_top()) return false; // Dead test on live IF.
2630 // If loop-varying exit-test, check for induction variable
2631 if( loop->is_member(get_loop(ctrl)) &&
2632 loop->is_loop_exit(iff) &&
2633 is_possible_iv_test(iff)) {
2634 Node* cmp = iff->in(1)->in(1);
2635 if (cmp->Opcode() == Op_CmpI) {
2636 peel_if = iff->as_If();
2637 } else {
2638 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2639 peel_if_cmpu = iff->as_If();
2640 }
2641 }
2642 }
2643 iff = idom(iff);
2644 }
2645 // Prefer signed compare over unsigned compare.
2646 IfNode* new_peel_if = NULL;
2647 if (peel_if == NULL) {
2648 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2649 return false; // No peel point found
2650 }
2651 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2652 if (new_peel_if == NULL) {
2653 return false; // No peel point found
2654 }
2655 peel_if = new_peel_if;
2656 }
2657 Node* last_peel = stay_in_loop(peel_if, loop);
2658 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2659 if (first_not_peeled == NULL || first_not_peeled == head) {
2660 return false;
2661 }
2662
2663 #if !defined(PRODUCT)
2664 if (TraceLoopOpts) {
2665 tty->print("PartialPeel ");
2666 loop->dump_head();
2667 }
2668
2669 if (TracePartialPeeling) {
2670 tty->print_cr("before partial peel one iteration");
2671 Node_List wl;
2672 Node* t = head->in(2);
2673 while (true) {
2674 wl.push(t);
2675 if (t == head) break;
2676 t = idom(t);
2677 }
2678 while (wl.size() > 0) {
2679 Node* tt = wl.pop();
2680 tt->dump();
2681 if (tt == last_peel) tty->print_cr("-- cut --");
2682 }
2683 }
2684 #endif
2685 ResourceArea *area = Thread::current()->resource_area();
2686 VectorSet peel(area);
2687 VectorSet not_peel(area);
2688 Node_List peel_list(area);
2689 Node_List worklist(area);
2690 Node_List sink_list(area);
2691
2692 // Set of cfg nodes to peel are those that are executable from
2693 // the head through last_peel.
2694 assert(worklist.size() == 0, "should be empty");
2695 worklist.push(head);
2696 peel.set(head->_idx);
2697 while (worklist.size() > 0) {
2698 Node *n = worklist.pop();
2699 if (n != last_peel) {
2700 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2701 Node* use = n->fast_out(j);
2702 if (use->is_CFG() &&
2703 loop->is_member(get_loop(use)) &&
2704 !peel.test_set(use->_idx)) {
2705 worklist.push(use);
2706 }
2707 }
2708 }
2709 }
2710
2711 // Set of non-cfg nodes to peel are those that are control
2712 // dependent on the cfg nodes.
2713 uint i;
2714 for(i = 0; i < loop->_body.size(); i++ ) {
2715 Node *n = loop->_body.at(i);
2716 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2717 if (peel.test(n_c->_idx)) {
2718 peel.set(n->_idx);
2719 } else {
2720 not_peel.set(n->_idx);
2721 }
2722 }
2723
2724 // Step 2: move operations from the peeled section down into the
2725 // not-peeled section
2726
2727 // Get a post order schedule of nodes in the peel region
2728 // Result in right-most operand.
2729 scheduled_nodelist(loop, peel, peel_list );
2730
2731 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2732
2733 // For future check for too many new phis
2734 uint old_phi_cnt = 0;
2735 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2736 Node* use = head->fast_out(j);
2737 if (use->is_Phi()) old_phi_cnt++;
2738 }
2739
2740 #if !defined(PRODUCT)
2741 if (TracePartialPeeling) {
2742 tty->print_cr("\npeeled list");
2743 }
2744 #endif
2745
2746 // Evacuate nodes in peel region into the not_peeled region if possible
2747 uint new_phi_cnt = 0;
2748 uint cloned_for_outside_use = 0;
2749 for (i = 0; i < peel_list.size();) {
2750 Node* n = peel_list.at(i);
2751 #if !defined(PRODUCT)
2752 if (TracePartialPeeling) n->dump();
2753 #endif
2754 bool incr = true;
2755 if ( !n->is_CFG() ) {
2756
2757 if ( has_use_in_set(n, not_peel) ) {
2758
2759 // If not used internal to the peeled region,
2760 // move "n" from peeled to not_peeled region.
2761
2762 if ( !has_use_internal_to_set(n, peel, loop) ) {
2763
2764 // if not pinned and not a load (which maybe anti-dependent on a store)
2765 // and not a CMove (Matcher expects only bool->cmove).
2766 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2767 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2768 sink_list.push(n);
2769 peel >>= n->_idx; // delete n from peel set.
2770 not_peel <<= n->_idx; // add n to not_peel set.
2771 peel_list.remove(i);
2772 incr = false;
2773 #if !defined(PRODUCT)
2774 if (TracePartialPeeling) {
2775 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2776 n->_idx, get_ctrl(n)->_idx);
2777 }
2778 #endif
2779 }
2780 } else {
2781 // Otherwise check for special def-use cases that span
2782 // the peel/not_peel boundary such as bool->if
2783 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2784 new_phi_cnt++;
2785 }
2786 }
2787 }
2788 if (incr) i++;
2789 }
2790
2791 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2792 #if !defined(PRODUCT)
2793 if (TracePartialPeeling) {
2794 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2795 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2796 }
2797 #endif
2798 if (new_peel_if != NULL) {
2799 remove_cmpi_loop_exit(new_peel_if, loop);
2800 }
2801 // Inhibit more partial peeling on this loop
2802 assert(!head->is_partial_peel_loop(), "not partial peeled");
2803 head->mark_partial_peel_failed();
2804 if (cloned_for_outside_use > 0) {
2805 // Terminate this round of loop opts because
2806 // the graph outside this loop was changed.
2807 C->set_major_progress();
2808 return true;
2809 }
2810 return false;
2811 }
2812
2813 // Step 3: clone loop, retarget control, and insert new phis
2814
2815 // Create new loop head for new phis and to hang
2816 // the nodes being moved (sinked) from the peel region.
2817 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2818 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2819 _igvn.register_new_node_with_optimizer(new_head);
2820 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2821 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2822 set_loop(new_head, loop);
2823 loop->_body.push(new_head);
2824 not_peel.set(new_head->_idx);
2825 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2826 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2827
2828 while (sink_list.size() > 0) {
2829 Node* n = sink_list.pop();
2830 set_ctrl(n, new_head);
2831 }
2832
2833 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2834
2835 clone_loop( loop, old_new, dd );
2836
2837 const uint clone_exit_idx = 1;
2838 const uint orig_exit_idx = 2;
2839 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2840
2841 Node* head_clone = old_new[head->_idx];
2842 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2843 Node* orig_tail_clone = head_clone->in(2);
2844
2845 // Add phi if "def" node is in peel set and "use" is not
2846
2847 for(i = 0; i < peel_list.size(); i++ ) {
2848 Node *def = peel_list.at(i);
2849 if (!def->is_CFG()) {
2850 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2851 Node *use = def->fast_out(j);
2852 if (has_node(use) && use->in(0) != C->top() &&
2853 (!peel.test(use->_idx) ||
2854 (use->is_Phi() && use->in(0) == head)) ) {
2855 worklist.push(use);
2856 }
2857 }
2858 while( worklist.size() ) {
2859 Node *use = worklist.pop();
2860 for (uint j = 1; j < use->req(); j++) {
2861 Node* n = use->in(j);
2862 if (n == def) {
2863
2864 // "def" is in peel set, "use" is not in peel set
2865 // or "use" is in the entry boundary (a phi) of the peel set
2866
2867 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2868
2869 if ( loop->is_member(get_loop( use_c )) ) {
2870 // use is in loop
2871 if (old_new[use->_idx] != NULL) { // null for dead code
2872 Node* use_clone = old_new[use->_idx];
2873 _igvn.replace_input_of(use, j, C->top());
2874 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2875 }
2876 } else {
2877 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2878 // use is not in the loop, check if the live range includes the cut
2879 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2880 if (not_peel.test(lp_if->_idx)) {
2881 assert(j == orig_exit_idx, "use from original loop");
2882 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2883 }
2884 }
2885 }
2886 }
2887 }
2888 }
2889 }
2890
2891 // Step 3b: retarget control
2892
2893 // Redirect control to the new loop head if a cloned node in
2894 // the not_peeled region has control that points into the peeled region.
2895 // This necessary because the cloned peeled region will be outside
2896 // the loop.
2897 // from to
2898 // cloned-peeled <---+
2899 // new_head_clone: | <--+
2900 // cloned-not_peeled in(0) in(0)
2901 // orig-peeled
2902
2903 for(i = 0; i < loop->_body.size(); i++ ) {
2904 Node *n = loop->_body.at(i);
2905 if (!n->is_CFG() && n->in(0) != NULL &&
2906 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2907 Node* n_clone = old_new[n->_idx];
2908 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2909 }
2910 }
2911
2912 // Backedge of the surviving new_head (the clone) is original last_peel
2913 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2914
2915 // Cut first node in original not_peel set
2916 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2917 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2918 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2919
2920 // Copy head_clone back-branch info to original head
2921 // and remove original head's loop entry and
2922 // clone head's back-branch
2923 _igvn.rehash_node_delayed(head); // Multiple edge updates
2924 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2925 head->set_req(LoopNode::LoopBackControl, C->top());
2926 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2927
2928 // Similarly modify the phis
2929 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2930 Node* use = head->fast_out(k);
2931 if (use->is_Phi() && use->outcnt() > 0) {
2932 Node* use_clone = old_new[use->_idx];
2933 _igvn.rehash_node_delayed(use); // Multiple edge updates
2934 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2935 use->set_req(LoopNode::LoopBackControl, C->top());
2936 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2937 }
2938 }
2939
2940 // Step 4: update dominator tree and dominator depth
2941
2942 set_idom(head, orig_tail_clone, dd);
2943 recompute_dom_depth();
2944
2945 // Inhibit more partial peeling on this loop
2946 new_head_clone->set_partial_peel_loop();
2947 C->set_major_progress();
2948 loop->record_for_igvn();
2949
2950 #if !defined(PRODUCT)
2951 if (TracePartialPeeling) {
2952 tty->print_cr("\nafter partial peel one iteration");
2953 Node_List wl(area);
2954 Node* t = last_peel;
2955 while (true) {
2956 wl.push(t);
2957 if (t == head_clone) break;
2958 t = idom(t);
2959 }
2960 while (wl.size() > 0) {
2961 Node* tt = wl.pop();
2962 if (tt == head) tty->print_cr("orig head");
2963 else if (tt == new_head_clone) tty->print_cr("new head");
2964 else if (tt == head_clone) tty->print_cr("clone head");
2965 tt->dump();
2966 }
2967 }
2968 #endif
2969 return true;
2970 }
2971
2972 //------------------------------reorg_offsets----------------------------------
2973 // Reorganize offset computations to lower register pressure. Mostly
2974 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2975 // then alive with the post-incremented trip counter forcing an extra
2976 // register move)
2977 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2978 // Perform it only for canonical counted loops.
2979 // Loop's shape could be messed up by iteration_split_impl.
2980 if (!loop->_head->is_CountedLoop())
2981 return;
2982 if (!loop->_head->as_Loop()->is_valid_counted_loop())
2983 return;
2984
2985 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2986 CountedLoopEndNode *cle = cl->loopexit();
2987 Node *exit = cle->proj_out(false);
2988 Node *phi = cl->phi();
2989
2990 // Check for the special case of folks using the pre-incremented
2991 // trip-counter on the fall-out path (forces the pre-incremented
2992 // and post-incremented trip counter to be live at the same time).
2993 // Fix this by adjusting to use the post-increment trip counter.
2994
2995 bool progress = true;
2996 while (progress) {
2997 progress = false;
2998 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
2999 Node* use = phi->fast_out(i); // User of trip-counter
3000 if (!has_ctrl(use)) continue;
3001 Node *u_ctrl = get_ctrl(use);
3002 if (use->is_Phi()) {
3003 u_ctrl = NULL;
3004 for (uint j = 1; j < use->req(); j++)
3005 if (use->in(j) == phi)
3006 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3007 }
3008 IdealLoopTree *u_loop = get_loop(u_ctrl);
3009 // Look for loop-invariant use
3010 if (u_loop == loop) continue;
3011 if (loop->is_member(u_loop)) continue;
3012 // Check that use is live out the bottom. Assuming the trip-counter
3013 // update is right at the bottom, uses of of the loop middle are ok.
3014 if (dom_lca(exit, u_ctrl) != exit) continue;
3015 // Hit! Refactor use to use the post-incremented tripcounter.
3016 // Compute a post-increment tripcounter.
3017 Node *opaq = new Opaque2Node( C, cle->incr() );
3018 register_new_node(opaq, exit);
3019 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3020 set_ctrl(neg_stride, C->root());
3021 Node *post = new AddINode( opaq, neg_stride);
3022 register_new_node(post, exit);
3023 _igvn.rehash_node_delayed(use);
3024 for (uint j = 1; j < use->req(); j++) {
3025 if (use->in(j) == phi)
3026 use->set_req(j, post);
3027 }
3028 // Since DU info changed, rerun loop
3029 progress = true;
3030 break;
3031 }
3032 }
3033
3034 }