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.
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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() && n->in(0) != NULL) {
677 Node* address = n->in(MemNode::Address);
678 Node* value = n->in(MemNode::ValueIn);
679 Node* mem = n->in(MemNode::Memory);
680 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
681 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
682
683 // - address and value must be loop invariant
684 // - memory must be a memory Phi for the loop
685 // - Store must be the only store on this memory slice in the
686 // loop: if there's another store following this one then value
687 // written at iteration i by the second store could be overwritten
688 // at iteration i+n by the first store: it's not safe to move the
689 // first store out of the loop
690 // - nothing must observe the Phi memory: it guarantees no read
691 // before the store and no early exit out of the loop
692 // With those conditions, we are also guaranteed the store post
693 // dominates the loop head. Otherwise there would be extra Phi
694 // involved between the loop's Phi and the store.
695
696 if (!n_loop->is_member(address_loop) &&
697 !n_loop->is_member(value_loop) &&
698 mem->is_Phi() && mem->in(0) == n_loop->_head &&
699 mem->outcnt() == 1 &&
700 mem->in(LoopNode::LoopBackControl) == n) {
701
702 #ifdef ASSERT
703 // Verify that store's control does post dominate loop entry and
704 // that there's no early exit of the loop before the store.
705 bool ctrl_ok = false;
706 {
707 // Follow control from loop head until n, we exit the loop or
708 // we reach the tail
709 ResourceMark rm;
710 Unique_Node_List wq;
711 wq.push(n_loop->_head);
712 assert(n_loop->_tail != NULL, "need a tail");
713 for (uint next = 0; next < wq.size(); ++next) {
714 Node *m = wq.at(next);
715 if (m == n->in(0)) {
716 ctrl_ok = true;
717 continue;
718 }
719 assert(!has_ctrl(m), "should be CFG");
720 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
721 ctrl_ok = false;
722 break;
723 }
724 enqueue_cfg_uses(m, wq);
725 }
726 }
727 assert(ctrl_ok, "bad control");
728 #endif
729
730 // move the Store
731 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
732 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
733 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
734 // Disconnect the phi now. An empty phi can confuse other
735 // optimizations in this pass of loop opts.
736 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
737 n_loop->_body.yank(mem);
738
739 IdealLoopTree* new_loop = get_loop(n->in(0));
740 set_ctrl_and_loop(n, n->in(0));
741
742 return n;
743 }
744 }
745 return NULL;
746 }
747
748 // Try moving a store out of a loop, right after the loop
749 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
750 if (n->is_Store() && n->in(0) != NULL) {
751 Node *n_ctrl = get_ctrl(n);
752 IdealLoopTree *n_loop = get_loop(n_ctrl);
753 // Store must be in a loop
754 if (n_loop != _ltree_root && !n_loop->_irreducible) {
755 Node* address = n->in(MemNode::Address);
756 Node* value = n->in(MemNode::ValueIn);
757 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
758 // address must be loop invariant
759 if (!n_loop->is_member(address_loop)) {
760 // Store must be last on this memory slice in the loop and
761 // nothing in the loop must observe it
762 Node* phi = NULL;
763 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
764 Node* u = n->fast_out(i);
765 if (has_ctrl(u)) { // control use?
766 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
767 if (!n_loop->is_member(u_loop)) {
768 continue;
769 }
770 if (u->is_Phi() && u->in(0) == n_loop->_head) {
771 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
772 assert(phi == NULL, "already found");
773 phi = u;
774 continue;
775 }
776 }
777 phi = NULL;
778 break;
779 }
780 if (phi != NULL) {
781 // Nothing in the loop before the store (next iteration)
782 // must observe the stored value
783 bool mem_ok = true;
784 {
785 ResourceMark rm;
786 Unique_Node_List wq;
787 wq.push(phi);
788 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
789 Node *m = wq.at(next);
790 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
791 Node* u = m->fast_out(i);
792 if (u->is_Store() || u->is_Phi()) {
793 if (u != n) {
794 wq.push(u);
795 mem_ok = (wq.size() <= 10);
796 }
797 } else {
798 mem_ok = false;
799 break;
800 }
801 }
802 }
803 }
804 if (mem_ok) {
805 // Move the Store out of the loop creating clones along
806 // all paths out of the loop that observe the stored value
807 _igvn.rehash_node_delayed(phi);
808 int count = phi->replace_edge(n, n->in(MemNode::Memory));
809 assert(count > 0, "inconsistent phi");
810 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
811 Node* u = n->fast_out(i);
812 Node* c = get_ctrl(u);
813
814 if (u->is_Phi()) {
815 c = u->in(0)->in(u->find_edge(n));
816 }
817 IdealLoopTree *u_loop = get_loop(c);
818 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
819 while(true) {
820 Node* next_c = find_non_split_ctrl(idom(c));
821 if (n_loop->is_member(get_loop(next_c))) {
822 break;
823 }
824 c = next_c;
825 }
826
827 Node* st = n->clone();
828 st->set_req(0, c);
829 _igvn.register_new_node_with_optimizer(st);
830
831 set_ctrl(st, c);
832 IdealLoopTree* new_loop = get_loop(c);
833 assert(new_loop != n_loop, "should be moved out of loop");
834 if (new_loop->_child == NULL) new_loop->_body.push(st);
835
836 _igvn.replace_input_of(u, u->find_edge(n), st);
837 --imax;
838 --i;
839 }
840
841
842 assert(n->outcnt() == 0, "all uses should be gone");
843 _igvn.replace_input_of(n, MemNode::Memory, C->top());
844 // Disconnect the phi now. An empty phi can confuse other
845 // optimizations in this pass of loop opts..
846 if (phi->in(LoopNode::LoopBackControl) == phi) {
847 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
848 n_loop->_body.yank(phi);
849 }
850 }
851 }
852 }
853 }
854 }
855 }
856
857 //------------------------------split_if_with_blocks_pre-----------------------
858 // Do the real work in a non-recursive function. Data nodes want to be
859 // cloned in the pre-order so they can feed each other nicely.
860 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
861 // Cloning these guys is unlikely to win
862 int n_op = n->Opcode();
863 if( n_op == Op_MergeMem ) return n;
864 if( n->is_Proj() ) return n;
865 // Do not clone-up CmpFXXX variations, as these are always
866 // followed by a CmpI
867 if( n->is_Cmp() ) return n;
868 // Attempt to use a conditional move instead of a phi/branch
869 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
870 Node *cmov = conditional_move( n );
871 if( cmov ) return cmov;
872 }
873 if( n->is_CFG() || n->is_LoadStore() )
874 return n;
875 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
876 n_op == Op_Opaque2 ) {
877 if( !C->major_progress() ) // If chance of no more loop opts...
878 _igvn._worklist.push(n); // maybe we'll remove them
879 return n;
880 }
881
882 if( n->is_Con() ) return n; // No cloning for Con nodes
883
884 Node *n_ctrl = get_ctrl(n);
885 if( !n_ctrl ) return n; // Dead node
886
887 Node* res = try_move_store_before_loop(n, n_ctrl);
888 if (res != NULL) {
889 return n;
890 }
891
892 // Attempt to remix address expressions for loop invariants
893 Node *m = remix_address_expressions( n );
894 if( m ) return m;
895
896 // Determine if the Node has inputs from some local Phi.
897 // Returns the block to clone thru.
898 Node *n_blk = has_local_phi_input( n );
899 if( !n_blk ) return n;
900
901 // Do not clone the trip counter through on a CountedLoop
902 // (messes up the canonical shape).
903 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
904
905 // Check for having no control input; not pinned. Allow
906 // dominating control.
907 if (n->in(0)) {
908 Node *dom = idom(n_blk);
909 if (dom_lca(n->in(0), dom) != n->in(0)) {
910 return n;
911 }
912 }
913 // Policy: when is it profitable. You must get more wins than
914 // policy before it is considered profitable. Policy is usually 0,
915 // so 1 win is considered profitable. Big merges will require big
916 // cloning, so get a larger policy.
917 int policy = n_blk->req() >> 2;
918
919 // If the loop is a candidate for range check elimination,
920 // delay splitting through it's phi until a later loop optimization
921 if (n_blk->is_CountedLoop()) {
922 IdealLoopTree *lp = get_loop(n_blk);
923 if (lp && lp->_rce_candidate) {
924 return n;
925 }
926 }
927
928 // Use same limit as split_if_with_blocks_post
929 if( C->live_nodes() > 35000 ) return n; // Method too big
930
931 // Split 'n' through the merge point if it is profitable
932 Node *phi = split_thru_phi( n, n_blk, policy );
933 if (!phi) return n;
934
935 // Found a Phi to split thru!
936 // Replace 'n' with the new phi
937 _igvn.replace_node( n, phi );
938 // Moved a load around the loop, 'en-registering' something.
939 if (n_blk->is_Loop() && n->is_Load() &&
940 !phi->in(LoopNode::LoopBackControl)->is_Load())
941 C->set_major_progress();
942
943 return phi;
944 }
945
946 static bool merge_point_too_heavy(Compile* C, Node* region) {
947 // Bail out if the region and its phis have too many users.
948 int weight = 0;
949 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
950 weight += region->fast_out(i)->outcnt();
951 }
952 int nodes_left = C->max_node_limit() - C->live_nodes();
953 if (weight * 8 > nodes_left) {
954 #ifndef PRODUCT
955 if (PrintOpto)
956 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
957 #endif
958 return true;
959 } else {
960 return false;
961 }
962 }
963
964 static bool merge_point_safe(Node* region) {
965 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
966 // having a PhiNode input. This sidesteps the dangerous case where the split
967 // ConvI2LNode may become TOP if the input Value() does not
968 // overlap the ConvI2L range, leaving a node which may not dominate its
969 // uses.
970 // A better fix for this problem can be found in the BugTraq entry, but
971 // expediency for Mantis demands this hack.
972 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
973 // split_if_with_blocks from splitting a block because we could not move around
974 // the FastLockNode.
975 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
976 Node* n = region->fast_out(i);
977 if (n->is_Phi()) {
978 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
979 Node* m = n->fast_out(j);
980 if (m->is_FastLock())
981 return false;
982 #ifdef _LP64
983 if (m->Opcode() == Op_ConvI2L)
984 return false;
985 #endif
986 }
987 }
988 }
989 return true;
990 }
991
992
993 //------------------------------place_near_use---------------------------------
994 // Place some computation next to use but not inside inner loops.
995 // For inner loop uses move it to the preheader area.
996 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
997 IdealLoopTree *u_loop = get_loop( useblock );
998 return (u_loop->_irreducible || u_loop->_child)
999 ? useblock
1000 : u_loop->_head->in(LoopNode::EntryControl);
1001 }
1002
1003
1004 //------------------------------split_if_with_blocks_post----------------------
1005 // Do the real work in a non-recursive function. CFG hackery wants to be
1006 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1007 // info.
1008 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1009
1010 // Cloning Cmp through Phi's involves the split-if transform.
1011 // FastLock is not used by an If
1012 if( n->is_Cmp() && !n->is_FastLock() ) {
1013 if( C->live_nodes() > 35000 ) return; // Method too big
1014
1015 // Do not do 'split-if' if irreducible loops are present.
1016 if( _has_irreducible_loops )
1017 return;
1018
1019 Node *n_ctrl = get_ctrl(n);
1020 // Determine if the Node has inputs from some local Phi.
1021 // Returns the block to clone thru.
1022 Node *n_blk = has_local_phi_input( n );
1023 if( n_blk != n_ctrl ) return;
1024
1025 if( merge_point_too_heavy(C, n_ctrl) )
1026 return;
1027
1028 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1029 Node *bol = n->unique_out();
1030 assert( bol->is_Bool(), "expect a bool here" );
1031 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1032 Node *iff = bol->unique_out();
1033
1034 // Check some safety conditions
1035 if( iff->is_If() ) { // Classic split-if?
1036 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1037 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1038 // Can't split CMove with different control edge.
1039 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1040 if( get_ctrl(iff->in(2)) == n_ctrl ||
1041 get_ctrl(iff->in(3)) == n_ctrl )
1042 return; // Inputs not yet split-up
1043 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1044 return; // Loop-invar test gates loop-varying CMOVE
1045 }
1046 } else {
1047 return; // some other kind of node, such as an Allocate
1048 }
1049
1050 // Do not do 'split-if' if some paths are dead. First do dead code
1051 // elimination and then see if its still profitable.
1052 for( uint i = 1; i < n_ctrl->req(); i++ )
1053 if( n_ctrl->in(i) == C->top() )
1054 return;
1055
1056 // When is split-if profitable? Every 'win' on means some control flow
1057 // goes dead, so it's almost always a win.
1058 int policy = 0;
1059 // If trying to do a 'Split-If' at the loop head, it is only
1060 // profitable if the cmp folds up on BOTH paths. Otherwise we
1061 // risk peeling a loop forever.
1062
1063 // CNC - Disabled for now. Requires careful handling of loop
1064 // body selection for the cloned code. Also, make sure we check
1065 // for any input path not being in the same loop as n_ctrl. For
1066 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1067 // because the alternative loop entry points won't be converted
1068 // into LoopNodes.
1069 IdealLoopTree *n_loop = get_loop(n_ctrl);
1070 for( uint j = 1; j < n_ctrl->req(); j++ )
1071 if( get_loop(n_ctrl->in(j)) != n_loop )
1072 return;
1073
1074 // Check for safety of the merge point.
1075 if( !merge_point_safe(n_ctrl) ) {
1076 return;
1077 }
1078
1079 // Split compare 'n' through the merge point if it is profitable
1080 Node *phi = split_thru_phi( n, n_ctrl, policy );
1081 if( !phi ) return;
1082
1083 // Found a Phi to split thru!
1084 // Replace 'n' with the new phi
1085 _igvn.replace_node( n, phi );
1086
1087 // Now split the bool up thru the phi
1088 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1089 guarantee(bolphi != NULL, "null boolean phi node");
1090
1091 _igvn.replace_node( bol, bolphi );
1092 assert( iff->in(1) == bolphi, "" );
1093
1094 if( bolphi->Value(&_igvn)->singleton() )
1095 return;
1096
1097 // Conditional-move? Must split up now
1098 if( !iff->is_If() ) {
1099 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1100 _igvn.replace_node( iff, cmovphi );
1101 return;
1102 }
1103
1104 // Now split the IF
1105 do_split_if( iff );
1106 return;
1107 }
1108
1109 // Check for an IF ready to split; one that has its
1110 // condition codes input coming from a Phi at the block start.
1111 int n_op = n->Opcode();
1112
1113 // Check for an IF being dominated by another IF same test
1114 if (n_op == Op_If) {
1115 Node *bol = n->in(1);
1116 uint max = bol->outcnt();
1117 // Check for same test used more than once?
1118 if (max > 1 && bol->is_Bool()) {
1119 // Search up IDOMs to see if this IF is dominated.
1120 Node *cutoff = get_ctrl(bol);
1121
1122 // Now search up IDOMs till cutoff, looking for a dominating test
1123 Node *prevdom = n;
1124 Node *dom = idom(prevdom);
1125 while (dom != cutoff) {
1126 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1127 // Replace the dominated test with an obvious true or false.
1128 // Place it on the IGVN worklist for later cleanup.
1129 C->set_major_progress();
1130 dominated_by(prevdom, n, false, true);
1131 #ifndef PRODUCT
1132 if( VerifyLoopOptimizations ) verify();
1133 #endif
1134 return;
1135 }
1136 prevdom = dom;
1137 dom = idom(prevdom);
1138 }
1139 }
1140 }
1141
1142 // See if a shared loop-varying computation has no loop-varying uses.
1143 // Happens if something is only used for JVM state in uncommon trap exits,
1144 // like various versions of induction variable+offset. Clone the
1145 // computation per usage to allow it to sink out of the loop.
1146 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1147 Node *n_ctrl = get_ctrl(n);
1148 IdealLoopTree *n_loop = get_loop(n_ctrl);
1149 if( n_loop != _ltree_root ) {
1150 DUIterator_Fast imax, i = n->fast_outs(imax);
1151 for (; i < imax; i++) {
1152 Node* u = n->fast_out(i);
1153 if( !has_ctrl(u) ) break; // Found control user
1154 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1155 if( u_loop == n_loop ) break; // Found loop-varying use
1156 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1157 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1158 }
1159 bool did_break = (i < imax); // Did we break out of the previous loop?
1160 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1161 Node *late_load_ctrl = NULL;
1162 if (n->is_Load()) {
1163 // If n is a load, get and save the result from get_late_ctrl(),
1164 // to be later used in calculating the control for n's clones.
1165 clear_dom_lca_tags();
1166 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1167 }
1168 // If n is a load, and the late control is the same as the current
1169 // control, then the cloning of n is a pointless exercise, because
1170 // GVN will ensure that we end up where we started.
1171 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1172 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1173 Node *u = n->last_out(j); // Clone private computation per use
1174 _igvn.rehash_node_delayed(u);
1175 Node *x = n->clone(); // Clone computation
1176 Node *x_ctrl = NULL;
1177 if( u->is_Phi() ) {
1178 // Replace all uses of normal nodes. Replace Phi uses
1179 // individually, so the separate Nodes can sink down
1180 // different paths.
1181 uint k = 1;
1182 while( u->in(k) != n ) k++;
1183 u->set_req( k, x );
1184 // x goes next to Phi input path
1185 x_ctrl = u->in(0)->in(k);
1186 --j;
1187 } else { // Normal use
1188 // Replace all uses
1189 for( uint k = 0; k < u->req(); k++ ) {
1190 if( u->in(k) == n ) {
1191 u->set_req( k, x );
1192 --j;
1193 }
1194 }
1195 x_ctrl = get_ctrl(u);
1196 }
1197
1198 // Find control for 'x' next to use but not inside inner loops.
1199 // For inner loop uses get the preheader area.
1200 x_ctrl = place_near_use(x_ctrl);
1201
1202 if (n->is_Load()) {
1203 // For loads, add a control edge to a CFG node outside of the loop
1204 // to force them to not combine and return back inside the loop
1205 // during GVN optimization (4641526).
1206 //
1207 // Because we are setting the actual control input, factor in
1208 // the result from get_late_ctrl() so we respect any
1209 // anti-dependences. (6233005).
1210 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1211
1212 // Don't allow the control input to be a CFG splitting node.
1213 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1214 // should only have IfTrueNode and IfFalseNode (4985384).
1215 x_ctrl = find_non_split_ctrl(x_ctrl);
1216 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1217
1218 x->set_req(0, x_ctrl);
1219 }
1220 register_new_node(x, x_ctrl);
1221
1222 // Some institutional knowledge is needed here: 'x' is
1223 // yanked because if the optimizer runs GVN on it all the
1224 // cloned x's will common up and undo this optimization and
1225 // be forced back in the loop. This is annoying because it
1226 // makes +VerifyOpto report false-positives on progress. I
1227 // tried setting control edges on the x's to force them to
1228 // not combine, but the matching gets worried when it tries
1229 // to fold a StoreP and an AddP together (as part of an
1230 // address expression) and the AddP and StoreP have
1231 // different controls.
1232 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1233 }
1234 _igvn.remove_dead_node(n);
1235 }
1236 }
1237 }
1238 }
1239
1240 try_move_store_after_loop(n);
1241
1242 // Check for Opaque2's who's loop has disappeared - who's input is in the
1243 // same loop nest as their output. Remove 'em, they are no longer useful.
1244 if( n_op == Op_Opaque2 &&
1245 n->in(1) != NULL &&
1246 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1247 _igvn.replace_node( n, n->in(1) );
1248 }
1249 }
1250
1251 //------------------------------split_if_with_blocks---------------------------
1252 // Check for aggressive application of 'split-if' optimization,
1253 // using basic block level info.
1254 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1255 Node *n = C->root();
1256 visited.set(n->_idx); // first, mark node as visited
1257 // Do pre-visit work for root
1258 n = split_if_with_blocks_pre( n );
1259 uint cnt = n->outcnt();
1260 uint i = 0;
1261 while (true) {
1262 // Visit all children
1263 if (i < cnt) {
1264 Node* use = n->raw_out(i);
1265 ++i;
1266 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1267 // Now do pre-visit work for this use
1268 use = split_if_with_blocks_pre( use );
1269 nstack.push(n, i); // Save parent and next use's index.
1270 n = use; // Process all children of current use.
1271 cnt = use->outcnt();
1272 i = 0;
1273 }
1274 }
1275 else {
1276 // All of n's children have been processed, complete post-processing.
1277 if (cnt != 0 && !n->is_Con()) {
1278 assert(has_node(n), "no dead nodes");
1279 split_if_with_blocks_post( n );
1280 }
1281 if (nstack.is_empty()) {
1282 // Finished all nodes on stack.
1283 break;
1284 }
1285 // Get saved parent node and next use's index. Visit the rest of uses.
1286 n = nstack.node();
1287 cnt = n->outcnt();
1288 i = nstack.index();
1289 nstack.pop();
1290 }
1291 }
1292 }
1293
1294
1295 //=============================================================================
1296 //
1297 // C L O N E A L O O P B O D Y
1298 //
1299
1300 //------------------------------clone_iff--------------------------------------
1301 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1302 // "Nearly" because all Nodes have been cloned from the original in the loop,
1303 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1304 // through the Phi recursively, and return a Bool.
1305 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1306
1307 // Convert this Phi into a Phi merging Bools
1308 uint i;
1309 for( i = 1; i < phi->req(); i++ ) {
1310 Node *b = phi->in(i);
1311 if( b->is_Phi() ) {
1312 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1313 } else {
1314 assert( b->is_Bool(), "" );
1315 }
1316 }
1317
1318 Node *sample_bool = phi->in(1);
1319 Node *sample_cmp = sample_bool->in(1);
1320
1321 // Make Phis to merge the Cmp's inputs.
1322 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1323 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1324 for( i = 1; i < phi->req(); i++ ) {
1325 Node *n1 = phi->in(i)->in(1)->in(1);
1326 Node *n2 = phi->in(i)->in(1)->in(2);
1327 phi1->set_req( i, n1 );
1328 phi2->set_req( i, n2 );
1329 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1330 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1331 }
1332 // See if these Phis have been made before.
1333 // Register with optimizer
1334 Node *hit1 = _igvn.hash_find_insert(phi1);
1335 if( hit1 ) { // Hit, toss just made Phi
1336 _igvn.remove_dead_node(phi1); // Remove new phi
1337 assert( hit1->is_Phi(), "" );
1338 phi1 = (PhiNode*)hit1; // Use existing phi
1339 } else { // Miss
1340 _igvn.register_new_node_with_optimizer(phi1);
1341 }
1342 Node *hit2 = _igvn.hash_find_insert(phi2);
1343 if( hit2 ) { // Hit, toss just made Phi
1344 _igvn.remove_dead_node(phi2); // Remove new phi
1345 assert( hit2->is_Phi(), "" );
1346 phi2 = (PhiNode*)hit2; // Use existing phi
1347 } else { // Miss
1348 _igvn.register_new_node_with_optimizer(phi2);
1349 }
1350 // Register Phis with loop/block info
1351 set_ctrl(phi1, phi->in(0));
1352 set_ctrl(phi2, phi->in(0));
1353 // Make a new Cmp
1354 Node *cmp = sample_cmp->clone();
1355 cmp->set_req( 1, phi1 );
1356 cmp->set_req( 2, phi2 );
1357 _igvn.register_new_node_with_optimizer(cmp);
1358 set_ctrl(cmp, phi->in(0));
1359
1360 // Make a new Bool
1361 Node *b = sample_bool->clone();
1362 b->set_req(1,cmp);
1363 _igvn.register_new_node_with_optimizer(b);
1364 set_ctrl(b, phi->in(0));
1365
1366 assert( b->is_Bool(), "" );
1367 return (BoolNode*)b;
1368 }
1369
1370 //------------------------------clone_bool-------------------------------------
1371 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1372 // "Nearly" because all Nodes have been cloned from the original in the loop,
1373 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1374 // through the Phi recursively, and return a Bool.
1375 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1376 uint i;
1377 // Convert this Phi into a Phi merging Bools
1378 for( i = 1; i < phi->req(); i++ ) {
1379 Node *b = phi->in(i);
1380 if( b->is_Phi() ) {
1381 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1382 } else {
1383 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1384 }
1385 }
1386
1387 Node *sample_cmp = phi->in(1);
1388
1389 // Make Phis to merge the Cmp's inputs.
1390 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1391 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1392 for( uint j = 1; j < phi->req(); j++ ) {
1393 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1394 Node *n1, *n2;
1395 if( cmp_top->is_Cmp() ) {
1396 n1 = cmp_top->in(1);
1397 n2 = cmp_top->in(2);
1398 } else {
1399 n1 = n2 = cmp_top;
1400 }
1401 phi1->set_req( j, n1 );
1402 phi2->set_req( j, n2 );
1403 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1404 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1405 }
1406
1407 // See if these Phis have been made before.
1408 // Register with optimizer
1409 Node *hit1 = _igvn.hash_find_insert(phi1);
1410 if( hit1 ) { // Hit, toss just made Phi
1411 _igvn.remove_dead_node(phi1); // Remove new phi
1412 assert( hit1->is_Phi(), "" );
1413 phi1 = (PhiNode*)hit1; // Use existing phi
1414 } else { // Miss
1415 _igvn.register_new_node_with_optimizer(phi1);
1416 }
1417 Node *hit2 = _igvn.hash_find_insert(phi2);
1418 if( hit2 ) { // Hit, toss just made Phi
1419 _igvn.remove_dead_node(phi2); // Remove new phi
1420 assert( hit2->is_Phi(), "" );
1421 phi2 = (PhiNode*)hit2; // Use existing phi
1422 } else { // Miss
1423 _igvn.register_new_node_with_optimizer(phi2);
1424 }
1425 // Register Phis with loop/block info
1426 set_ctrl(phi1, phi->in(0));
1427 set_ctrl(phi2, phi->in(0));
1428 // Make a new Cmp
1429 Node *cmp = sample_cmp->clone();
1430 cmp->set_req( 1, phi1 );
1431 cmp->set_req( 2, phi2 );
1432 _igvn.register_new_node_with_optimizer(cmp);
1433 set_ctrl(cmp, phi->in(0));
1434
1435 assert( cmp->is_Cmp(), "" );
1436 return (CmpNode*)cmp;
1437 }
1438
1439 //------------------------------sink_use---------------------------------------
1440 // If 'use' was in the loop-exit block, it now needs to be sunk
1441 // below the post-loop merge point.
1442 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1443 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1444 set_ctrl(use, post_loop);
1445 for (DUIterator j = use->outs(); use->has_out(j); j++)
1446 sink_use(use->out(j), post_loop);
1447 }
1448 }
1449
1450 //------------------------------clone_loop-------------------------------------
1451 //
1452 // C L O N E A L O O P B O D Y
1453 //
1454 // This is the basic building block of the loop optimizations. It clones an
1455 // entire loop body. It makes an old_new loop body mapping; with this mapping
1456 // you can find the new-loop equivalent to an old-loop node. All new-loop
1457 // nodes are exactly equal to their old-loop counterparts, all edges are the
1458 // same. All exits from the old-loop now have a RegionNode that merges the
1459 // equivalent new-loop path. This is true even for the normal "loop-exit"
1460 // condition. All uses of loop-invariant old-loop values now come from (one
1461 // or more) Phis that merge their new-loop equivalents.
1462 //
1463 // This operation leaves the graph in an illegal state: there are two valid
1464 // control edges coming from the loop pre-header to both loop bodies. I'll
1465 // definitely have to hack the graph after running this transform.
1466 //
1467 // From this building block I will further edit edges to perform loop peeling
1468 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1469 //
1470 // Parameter side_by_size_idom:
1471 // When side_by_size_idom is NULL, the dominator tree is constructed for
1472 // the clone loop to dominate the original. Used in construction of
1473 // pre-main-post loop sequence.
1474 // When nonnull, the clone and original are side-by-side, both are
1475 // dominated by the side_by_side_idom node. Used in construction of
1476 // unswitched loops.
1477 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1478 Node* side_by_side_idom) {
1479
1480 #ifndef PRODUCT
1481 if (C->do_vector_loop() && PrintOpto) {
1482 const char* mname = C->method()->name()->as_quoted_ascii();
1483 if (mname != NULL) {
1484 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1485 }
1486 }
1487 #endif
1488
1489 CloneMap& cm = C->clone_map();
1490 Dict* dict = cm.dict();
1491 if (C->do_vector_loop()) {
1492 cm.set_clone_idx(cm.max_gen()+1);
1493 #ifndef PRODUCT
1494 if (PrintOpto) {
1495 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1496 loop->dump_head();
1497 }
1498 #endif
1499 }
1500
1501 // Step 1: Clone the loop body. Make the old->new mapping.
1502 uint i;
1503 for( i = 0; i < loop->_body.size(); i++ ) {
1504 Node *old = loop->_body.at(i);
1505 Node *nnn = old->clone();
1506 old_new.map( old->_idx, nnn );
1507 if (C->do_vector_loop()) {
1508 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1509 }
1510 _igvn.register_new_node_with_optimizer(nnn);
1511 }
1512
1513
1514 // Step 2: Fix the edges in the new body. If the old input is outside the
1515 // loop use it. If the old input is INside the loop, use the corresponding
1516 // new node instead.
1517 for( i = 0; i < loop->_body.size(); i++ ) {
1518 Node *old = loop->_body.at(i);
1519 Node *nnn = old_new[old->_idx];
1520 // Fix CFG/Loop controlling the new node
1521 if (has_ctrl(old)) {
1522 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1523 } else {
1524 set_loop(nnn, loop->_parent);
1525 if (old->outcnt() > 0) {
1526 set_idom( nnn, old_new[idom(old)->_idx], dd );
1527 }
1528 }
1529 // Correct edges to the new node
1530 for( uint j = 0; j < nnn->req(); j++ ) {
1531 Node *n = nnn->in(j);
1532 if( n ) {
1533 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1534 if( loop->is_member( old_in_loop ) )
1535 nnn->set_req(j, old_new[n->_idx]);
1536 }
1537 }
1538 _igvn.hash_find_insert(nnn);
1539 }
1540 Node *newhead = old_new[loop->_head->_idx];
1541 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1542
1543
1544 // Step 3: Now fix control uses. Loop varying control uses have already
1545 // been fixed up (as part of all input edges in Step 2). Loop invariant
1546 // control uses must be either an IfFalse or an IfTrue. Make a merge
1547 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1548 // refer to this.
1549 ResourceArea *area = Thread::current()->resource_area();
1550 Node_List worklist(area);
1551 uint new_counter = C->unique();
1552 for( i = 0; i < loop->_body.size(); i++ ) {
1553 Node* old = loop->_body.at(i);
1554 if( !old->is_CFG() ) continue;
1555 Node* nnn = old_new[old->_idx];
1556
1557 // Copy uses to a worklist, so I can munge the def-use info
1558 // with impunity.
1559 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1560 worklist.push(old->fast_out(j));
1561
1562 while( worklist.size() ) { // Visit all uses
1563 Node *use = worklist.pop();
1564 if (!has_node(use)) continue; // Ignore dead nodes
1565 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1566 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1567 // Both OLD and USE are CFG nodes here.
1568 assert( use->is_Proj(), "" );
1569
1570 // Clone the loop exit control projection
1571 Node *newuse = use->clone();
1572 if (C->do_vector_loop()) {
1573 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1574 }
1575 newuse->set_req(0,nnn);
1576 _igvn.register_new_node_with_optimizer(newuse);
1577 set_loop(newuse, use_loop);
1578 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1579
1580 // We need a Region to merge the exit from the peeled body and the
1581 // exit from the old loop body.
1582 RegionNode *r = new RegionNode(3);
1583 // Map the old use to the new merge point
1584 old_new.map( use->_idx, r );
1585 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1586 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1587
1588 // The original user of 'use' uses 'r' instead.
1589 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1590 Node* useuse = use->last_out(l);
1591 _igvn.rehash_node_delayed(useuse);
1592 uint uses_found = 0;
1593 if( useuse->in(0) == use ) {
1594 useuse->set_req(0, r);
1595 uses_found++;
1596 if( useuse->is_CFG() ) {
1597 assert( dom_depth(useuse) > dd_r, "" );
1598 set_idom(useuse, r, dom_depth(useuse));
1599 }
1600 }
1601 for( uint k = 1; k < useuse->req(); k++ ) {
1602 if( useuse->in(k) == use ) {
1603 useuse->set_req(k, r);
1604 uses_found++;
1605 }
1606 }
1607 l -= uses_found; // we deleted 1 or more copies of this edge
1608 }
1609
1610 // Now finish up 'r'
1611 r->set_req( 1, newuse );
1612 r->set_req( 2, use );
1613 _igvn.register_new_node_with_optimizer(r);
1614 set_loop(r, use_loop);
1615 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1616 } // End of if a loop-exit test
1617 }
1618 }
1619
1620 // Step 4: If loop-invariant use is not control, it must be dominated by a
1621 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1622 // there if needed. Make a Phi there merging old and new used values.
1623 Node_List *split_if_set = NULL;
1624 Node_List *split_bool_set = NULL;
1625 Node_List *split_cex_set = NULL;
1626 for( i = 0; i < loop->_body.size(); i++ ) {
1627 Node* old = loop->_body.at(i);
1628 Node* nnn = old_new[old->_idx];
1629 // Copy uses to a worklist, so I can munge the def-use info
1630 // with impunity.
1631 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1632 worklist.push(old->fast_out(j));
1633
1634 while( worklist.size() ) {
1635 Node *use = worklist.pop();
1636 if (!has_node(use)) continue; // Ignore dead nodes
1637 if (use->in(0) == C->top()) continue;
1638 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1639 // Check for data-use outside of loop - at least one of OLD or USE
1640 // must not be a CFG node.
1641 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1642
1643 // If the Data use is an IF, that means we have an IF outside of the
1644 // loop that is switching on a condition that is set inside of the
1645 // loop. Happens if people set a loop-exit flag; then test the flag
1646 // in the loop to break the loop, then test is again outside of the
1647 // loop to determine which way the loop exited.
1648 // Loop predicate If node connects to Bool node through Opaque1 node.
1649 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1650 // Since this code is highly unlikely, we lazily build the worklist
1651 // of such Nodes to go split.
1652 if( !split_if_set )
1653 split_if_set = new Node_List(area);
1654 split_if_set->push(use);
1655 }
1656 if( use->is_Bool() ) {
1657 if( !split_bool_set )
1658 split_bool_set = new Node_List(area);
1659 split_bool_set->push(use);
1660 }
1661 if( use->Opcode() == Op_CreateEx ) {
1662 if( !split_cex_set )
1663 split_cex_set = new Node_List(area);
1664 split_cex_set->push(use);
1665 }
1666
1667
1668 // Get "block" use is in
1669 uint idx = 0;
1670 while( use->in(idx) != old ) idx++;
1671 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1672 assert( !loop->is_member( get_loop( prev ) ), "" );
1673 Node *cfg = prev->_idx >= new_counter
1674 ? prev->in(2)
1675 : idom(prev);
1676 if( use->is_Phi() ) // Phi use is in prior block
1677 cfg = prev->in(idx); // NOT in block of Phi itself
1678 if (cfg->is_top()) { // Use is dead?
1679 _igvn.replace_input_of(use, idx, C->top());
1680 continue;
1681 }
1682
1683 while( !loop->is_member( get_loop( cfg ) ) ) {
1684 prev = cfg;
1685 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1686 }
1687 // If the use occurs after merging several exits from the loop, then
1688 // old value must have dominated all those exits. Since the same old
1689 // value was used on all those exits we did not need a Phi at this
1690 // merge point. NOW we do need a Phi here. Each loop exit value
1691 // is now merged with the peeled body exit; each exit gets its own
1692 // private Phi and those Phis need to be merged here.
1693 Node *phi;
1694 if( prev->is_Region() ) {
1695 if( idx == 0 ) { // Updating control edge?
1696 phi = prev; // Just use existing control
1697 } else { // Else need a new Phi
1698 phi = PhiNode::make( prev, old );
1699 // Now recursively fix up the new uses of old!
1700 for( uint i = 1; i < prev->req(); i++ ) {
1701 worklist.push(phi); // Onto worklist once for each 'old' input
1702 }
1703 }
1704 } else {
1705 // Get new RegionNode merging old and new loop exits
1706 prev = old_new[prev->_idx];
1707 assert( prev, "just made this in step 7" );
1708 if( idx == 0 ) { // Updating control edge?
1709 phi = prev; // Just use existing control
1710 } else { // Else need a new Phi
1711 // Make a new Phi merging data values properly
1712 phi = PhiNode::make( prev, old );
1713 phi->set_req( 1, nnn );
1714 }
1715 }
1716 // If inserting a new Phi, check for prior hits
1717 if( idx != 0 ) {
1718 Node *hit = _igvn.hash_find_insert(phi);
1719 if( hit == NULL ) {
1720 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1721 } else { // or
1722 // Remove the new phi from the graph and use the hit
1723 _igvn.remove_dead_node(phi);
1724 phi = hit; // Use existing phi
1725 }
1726 set_ctrl(phi, prev);
1727 }
1728 // Make 'use' use the Phi instead of the old loop body exit value
1729 _igvn.replace_input_of(use, idx, phi);
1730 if( use->_idx >= new_counter ) { // If updating new phis
1731 // Not needed for correctness, but prevents a weak assert
1732 // in AddPNode from tripping (when we end up with different
1733 // base & derived Phis that will become the same after
1734 // IGVN does CSE).
1735 Node *hit = _igvn.hash_find_insert(use);
1736 if( hit ) // Go ahead and re-hash for hits.
1737 _igvn.replace_node( use, hit );
1738 }
1739
1740 // If 'use' was in the loop-exit block, it now needs to be sunk
1741 // below the post-loop merge point.
1742 sink_use( use, prev );
1743 }
1744 }
1745 }
1746
1747 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1748 // the loop uses a condition set in the loop. The original IF probably
1749 // takes control from one or more OLD Regions (which in turn get from NEW
1750 // Regions). In any case, there will be a set of Phis for each merge point
1751 // from the IF up to where the original BOOL def exists the loop.
1752 if( split_if_set ) {
1753 while( split_if_set->size() ) {
1754 Node *iff = split_if_set->pop();
1755 if( iff->in(1)->is_Phi() ) {
1756 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1757 _igvn.replace_input_of(iff, 1, b);
1758 }
1759 }
1760 }
1761 if( split_bool_set ) {
1762 while( split_bool_set->size() ) {
1763 Node *b = split_bool_set->pop();
1764 Node *phi = b->in(1);
1765 assert( phi->is_Phi(), "" );
1766 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1767 _igvn.replace_input_of(b, 1, cmp);
1768 }
1769 }
1770 if( split_cex_set ) {
1771 while( split_cex_set->size() ) {
1772 Node *b = split_cex_set->pop();
1773 assert( b->in(0)->is_Region(), "" );
1774 assert( b->in(1)->is_Phi(), "" );
1775 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1776 split_up( b, b->in(0), NULL );
1777 }
1778 }
1779
1780 }
1781
1782
1783 //---------------------- stride_of_possible_iv -------------------------------------
1784 // Looks for an iff/bool/comp with one operand of the compare
1785 // being a cycle involving an add and a phi,
1786 // with an optional truncation (left-shift followed by a right-shift)
1787 // of the add. Returns zero if not an iv.
1788 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1789 Node* trunc1 = NULL;
1790 Node* trunc2 = NULL;
1791 const TypeInt* ttype = NULL;
1792 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1793 return 0;
1794 }
1795 BoolNode* bl = iff->in(1)->as_Bool();
1796 Node* cmp = bl->in(1);
1797 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1798 return 0;
1799 }
1800 // Must have an invariant operand
1801 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1802 return 0;
1803 }
1804 Node* add2 = NULL;
1805 Node* cmp1 = cmp->in(1);
1806 if (cmp1->is_Phi()) {
1807 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1808 Node* phi = cmp1;
1809 for (uint i = 1; i < phi->req(); i++) {
1810 Node* in = phi->in(i);
1811 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1812 &trunc1, &trunc2, &ttype);
1813 if (add && add->in(1) == phi) {
1814 add2 = add->in(2);
1815 break;
1816 }
1817 }
1818 } else {
1819 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1820 Node* addtrunc = cmp1;
1821 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1822 &trunc1, &trunc2, &ttype);
1823 if (add && add->in(1)->is_Phi()) {
1824 Node* phi = add->in(1);
1825 for (uint i = 1; i < phi->req(); i++) {
1826 if (phi->in(i) == addtrunc) {
1827 add2 = add->in(2);
1828 break;
1829 }
1830 }
1831 }
1832 }
1833 if (add2 != NULL) {
1834 const TypeInt* add2t = _igvn.type(add2)->is_int();
1835 if (add2t->is_con()) {
1836 return add2t->get_con();
1837 }
1838 }
1839 return 0;
1840 }
1841
1842
1843 //---------------------- stay_in_loop -------------------------------------
1844 // Return the (unique) control output node that's in the loop (if it exists.)
1845 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1846 Node* unique = NULL;
1847 if (!n) return NULL;
1848 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1849 Node* use = n->fast_out(i);
1850 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1851 if (unique != NULL) {
1852 return NULL;
1853 }
1854 unique = use;
1855 }
1856 }
1857 return unique;
1858 }
1859
1860 //------------------------------ register_node -------------------------------------
1861 // Utility to register node "n" with PhaseIdealLoop
1862 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1863 _igvn.register_new_node_with_optimizer(n);
1864 loop->_body.push(n);
1865 if (n->is_CFG()) {
1866 set_loop(n, loop);
1867 set_idom(n, pred, ddepth);
1868 } else {
1869 set_ctrl(n, pred);
1870 }
1871 }
1872
1873 //------------------------------ proj_clone -------------------------------------
1874 // Utility to create an if-projection
1875 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1876 ProjNode* c = p->clone()->as_Proj();
1877 c->set_req(0, iff);
1878 return c;
1879 }
1880
1881 //------------------------------ short_circuit_if -------------------------------------
1882 // Force the iff control output to be the live_proj
1883 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1884 guarantee(live_proj != NULL, "null projection");
1885 int proj_con = live_proj->_con;
1886 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1887 Node *con = _igvn.intcon(proj_con);
1888 set_ctrl(con, C->root());
1889 if (iff) {
1890 iff->set_req(1, con);
1891 }
1892 return con;
1893 }
1894
1895 //------------------------------ insert_if_before_proj -------------------------------------
1896 // Insert a new if before an if projection (* - new node)
1897 //
1898 // before
1899 // if(test)
1900 // / \
1901 // v v
1902 // other-proj proj (arg)
1903 //
1904 // after
1905 // if(test)
1906 // / \
1907 // / v
1908 // | * proj-clone
1909 // v |
1910 // other-proj v
1911 // * new_if(relop(cmp[IU](left,right)))
1912 // / \
1913 // v v
1914 // * new-proj proj
1915 // (returned)
1916 //
1917 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1918 IfNode* iff = proj->in(0)->as_If();
1919 IdealLoopTree *loop = get_loop(proj);
1920 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1921 int ddepth = dom_depth(proj);
1922
1923 _igvn.rehash_node_delayed(iff);
1924 _igvn.rehash_node_delayed(proj);
1925
1926 proj->set_req(0, NULL); // temporary disconnect
1927 ProjNode* proj2 = proj_clone(proj, iff);
1928 register_node(proj2, loop, iff, ddepth);
1929
1930 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1931 register_node(cmp, loop, proj2, ddepth);
1932
1933 BoolNode* bol = new BoolNode(cmp, relop);
1934 register_node(bol, loop, proj2, ddepth);
1935
1936 IfNode* new_if = new IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1937 register_node(new_if, loop, proj2, ddepth);
1938
1939 proj->set_req(0, new_if); // reattach
1940 set_idom(proj, new_if, ddepth);
1941
1942 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1943 guarantee(new_exit != NULL, "null exit node");
1944 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1945
1946 return new_exit;
1947 }
1948
1949 //------------------------------ insert_region_before_proj -------------------------------------
1950 // Insert a region before an if projection (* - new node)
1951 //
1952 // before
1953 // if(test)
1954 // / |
1955 // v |
1956 // proj v
1957 // other-proj
1958 //
1959 // after
1960 // if(test)
1961 // / |
1962 // v |
1963 // * proj-clone v
1964 // | other-proj
1965 // v
1966 // * new-region
1967 // |
1968 // v
1969 // * dum_if
1970 // / \
1971 // v \
1972 // * dum-proj v
1973 // proj
1974 //
1975 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1976 IfNode* iff = proj->in(0)->as_If();
1977 IdealLoopTree *loop = get_loop(proj);
1978 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1979 int ddepth = dom_depth(proj);
1980
1981 _igvn.rehash_node_delayed(iff);
1982 _igvn.rehash_node_delayed(proj);
1983
1984 proj->set_req(0, NULL); // temporary disconnect
1985 ProjNode* proj2 = proj_clone(proj, iff);
1986 register_node(proj2, loop, iff, ddepth);
1987
1988 RegionNode* reg = new RegionNode(2);
1989 reg->set_req(1, proj2);
1990 register_node(reg, loop, iff, ddepth);
1991
1992 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
1993 register_node(dum_if, loop, reg, ddepth);
1994
1995 proj->set_req(0, dum_if); // reattach
1996 set_idom(proj, dum_if, ddepth);
1997
1998 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
1999 register_node(dum_proj, loop, dum_if, ddepth);
2000
2001 return reg;
2002 }
2003
2004 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2005 // Clone a signed compare loop exit from an unsigned compare and
2006 // insert it before the unsigned cmp on the stay-in-loop path.
2007 // All new nodes inserted in the dominator tree between the original
2008 // if and it's projections. The original if test is replaced with
2009 // a constant to force the stay-in-loop path.
2010 //
2011 // This is done to make sure that the original if and it's projections
2012 // still dominate the same set of control nodes, that the ctrl() relation
2013 // from data nodes to them is preserved, and that their loop nesting is
2014 // preserved.
2015 //
2016 // before
2017 // if(i <u limit) unsigned compare loop exit
2018 // / |
2019 // v v
2020 // exit-proj stay-in-loop-proj
2021 //
2022 // after
2023 // if(stay-in-loop-const) original if
2024 // / |
2025 // / v
2026 // / if(i < limit) new signed test
2027 // / / |
2028 // / / v
2029 // / / if(i <u limit) new cloned unsigned test
2030 // / / / |
2031 // v v v |
2032 // region |
2033 // | |
2034 // dum-if |
2035 // / | |
2036 // ether | |
2037 // v v
2038 // exit-proj stay-in-loop-proj
2039 //
2040 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2041 const bool Signed = true;
2042 const bool Unsigned = false;
2043
2044 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2045 if (bol->_test._test != BoolTest::lt) return NULL;
2046 CmpNode* cmpu = bol->in(1)->as_Cmp();
2047 if (cmpu->Opcode() != Op_CmpU) return NULL;
2048 int stride = stride_of_possible_iv(if_cmpu);
2049 if (stride == 0) return NULL;
2050
2051 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2052 guarantee(lp_proj != NULL, "null loop node");
2053
2054 ProjNode* lp_continue = lp_proj->as_Proj();
2055 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2056
2057 Node* limit = NULL;
2058 if (stride > 0) {
2059 limit = cmpu->in(2);
2060 } else {
2061 limit = _igvn.makecon(TypeInt::ZERO);
2062 set_ctrl(limit, C->root());
2063 }
2064 // Create a new region on the exit path
2065 RegionNode* reg = insert_region_before_proj(lp_exit);
2066 guarantee(reg != NULL, "null region node");
2067
2068 // Clone the if-cmpu-true-false using a signed compare
2069 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2070 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2071 reg->add_req(cmpi_exit);
2072
2073 // Clone the if-cmpu-true-false
2074 BoolTest::mask rel_u = bol->_test._test;
2075 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2076 reg->add_req(cmpu_exit);
2077
2078 // Force original if to stay in loop.
2079 short_circuit_if(if_cmpu, lp_continue);
2080
2081 return cmpi_exit->in(0)->as_If();
2082 }
2083
2084 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2085 // Remove a previously inserted signed compare loop exit.
2086 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2087 Node* lp_proj = stay_in_loop(if_cmp, loop);
2088 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2089 stay_in_loop(lp_proj, loop)->is_If() &&
2090 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2091 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2092 set_ctrl(con, C->root());
2093 if_cmp->set_req(1, con);
2094 }
2095
2096 //------------------------------ scheduled_nodelist -------------------------------------
2097 // Create a post order schedule of nodes that are in the
2098 // "member" set. The list is returned in "sched".
2099 // The first node in "sched" is the loop head, followed by
2100 // nodes which have no inputs in the "member" set, and then
2101 // followed by the nodes that have an immediate input dependence
2102 // on a node in "sched".
2103 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2104
2105 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2106 Arena *a = Thread::current()->resource_area();
2107 VectorSet visited(a);
2108 Node_Stack nstack(a, loop->_body.size());
2109
2110 Node* n = loop->_head; // top of stack is cached in "n"
2111 uint idx = 0;
2112 visited.set(n->_idx);
2113
2114 // Initially push all with no inputs from within member set
2115 for(uint i = 0; i < loop->_body.size(); i++ ) {
2116 Node *elt = loop->_body.at(i);
2117 if (member.test(elt->_idx)) {
2118 bool found = false;
2119 for (uint j = 0; j < elt->req(); j++) {
2120 Node* def = elt->in(j);
2121 if (def && member.test(def->_idx) && def != elt) {
2122 found = true;
2123 break;
2124 }
2125 }
2126 if (!found && elt != loop->_head) {
2127 nstack.push(n, idx);
2128 n = elt;
2129 assert(!visited.test(n->_idx), "not seen yet");
2130 visited.set(n->_idx);
2131 }
2132 }
2133 }
2134
2135 // traverse out's that are in the member set
2136 while (true) {
2137 if (idx < n->outcnt()) {
2138 Node* use = n->raw_out(idx);
2139 idx++;
2140 if (!visited.test_set(use->_idx)) {
2141 if (member.test(use->_idx)) {
2142 nstack.push(n, idx);
2143 n = use;
2144 idx = 0;
2145 }
2146 }
2147 } else {
2148 // All outputs processed
2149 sched.push(n);
2150 if (nstack.is_empty()) break;
2151 n = nstack.node();
2152 idx = nstack.index();
2153 nstack.pop();
2154 }
2155 }
2156 }
2157
2158
2159 //------------------------------ has_use_in_set -------------------------------------
2160 // Has a use in the vector set
2161 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2162 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2163 Node* use = n->fast_out(j);
2164 if (vset.test(use->_idx)) {
2165 return true;
2166 }
2167 }
2168 return false;
2169 }
2170
2171
2172 //------------------------------ has_use_internal_to_set -------------------------------------
2173 // Has use internal to the vector set (ie. not in a phi at the loop head)
2174 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2175 Node* head = loop->_head;
2176 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2177 Node* use = n->fast_out(j);
2178 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2179 return true;
2180 }
2181 }
2182 return false;
2183 }
2184
2185
2186 //------------------------------ clone_for_use_outside_loop -------------------------------------
2187 // clone "n" for uses that are outside of loop
2188 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2189 int cloned = 0;
2190 assert(worklist.size() == 0, "should be empty");
2191 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2192 Node* use = n->fast_out(j);
2193 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2194 worklist.push(use);
2195 }
2196 }
2197 while( worklist.size() ) {
2198 Node *use = worklist.pop();
2199 if (!has_node(use) || use->in(0) == C->top()) continue;
2200 uint j;
2201 for (j = 0; j < use->req(); j++) {
2202 if (use->in(j) == n) break;
2203 }
2204 assert(j < use->req(), "must be there");
2205
2206 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2207 Node* n_clone = n->clone();
2208 _igvn.replace_input_of(use, j, n_clone);
2209 cloned++;
2210 Node* use_c;
2211 if (!use->is_Phi()) {
2212 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2213 } else {
2214 // Use in a phi is considered a use in the associated predecessor block
2215 use_c = use->in(0)->in(j);
2216 }
2217 set_ctrl(n_clone, use_c);
2218 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2219 get_loop(use_c)->_body.push(n_clone);
2220 _igvn.register_new_node_with_optimizer(n_clone);
2221 #if !defined(PRODUCT)
2222 if (TracePartialPeeling) {
2223 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2224 }
2225 #endif
2226 }
2227 return cloned;
2228 }
2229
2230
2231 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2232 // clone "n" for special uses that are in the not_peeled region.
2233 // If these def-uses occur in separate blocks, the code generator
2234 // marks the method as not compilable. For example, if a "BoolNode"
2235 // is in a different basic block than the "IfNode" that uses it, then
2236 // the compilation is aborted in the code generator.
2237 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2238 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2239 if (n->is_Phi() || n->is_Load()) {
2240 return;
2241 }
2242 assert(worklist.size() == 0, "should be empty");
2243 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2244 Node* use = n->fast_out(j);
2245 if ( not_peel.test(use->_idx) &&
2246 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2247 use->in(1) == n) {
2248 worklist.push(use);
2249 }
2250 }
2251 if (worklist.size() > 0) {
2252 // clone "n" and insert it between inputs of "n" and the use
2253 Node* n_clone = n->clone();
2254 loop->_body.push(n_clone);
2255 _igvn.register_new_node_with_optimizer(n_clone);
2256 set_ctrl(n_clone, get_ctrl(n));
2257 sink_list.push(n_clone);
2258 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2259 #if !defined(PRODUCT)
2260 if (TracePartialPeeling) {
2261 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2262 }
2263 #endif
2264 while( worklist.size() ) {
2265 Node *use = worklist.pop();
2266 _igvn.rehash_node_delayed(use);
2267 for (uint j = 1; j < use->req(); j++) {
2268 if (use->in(j) == n) {
2269 use->set_req(j, n_clone);
2270 }
2271 }
2272 }
2273 }
2274 }
2275
2276
2277 //------------------------------ insert_phi_for_loop -------------------------------------
2278 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2279 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2280 Node *phi = PhiNode::make(lp, back_edge_val);
2281 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2282 // Use existing phi if it already exists
2283 Node *hit = _igvn.hash_find_insert(phi);
2284 if( hit == NULL ) {
2285 _igvn.register_new_node_with_optimizer(phi);
2286 set_ctrl(phi, lp);
2287 } else {
2288 // Remove the new phi from the graph and use the hit
2289 _igvn.remove_dead_node(phi);
2290 phi = hit;
2291 }
2292 _igvn.replace_input_of(use, idx, phi);
2293 }
2294
2295 #ifdef ASSERT
2296 //------------------------------ is_valid_loop_partition -------------------------------------
2297 // Validate the loop partition sets: peel and not_peel
2298 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2299 VectorSet& not_peel ) {
2300 uint i;
2301 // Check that peel_list entries are in the peel set
2302 for (i = 0; i < peel_list.size(); i++) {
2303 if (!peel.test(peel_list.at(i)->_idx)) {
2304 return false;
2305 }
2306 }
2307 // Check at loop members are in one of peel set or not_peel set
2308 for (i = 0; i < loop->_body.size(); i++ ) {
2309 Node *def = loop->_body.at(i);
2310 uint di = def->_idx;
2311 // Check that peel set elements are in peel_list
2312 if (peel.test(di)) {
2313 if (not_peel.test(di)) {
2314 return false;
2315 }
2316 // Must be in peel_list also
2317 bool found = false;
2318 for (uint j = 0; j < peel_list.size(); j++) {
2319 if (peel_list.at(j)->_idx == di) {
2320 found = true;
2321 break;
2322 }
2323 }
2324 if (!found) {
2325 return false;
2326 }
2327 } else if (not_peel.test(di)) {
2328 if (peel.test(di)) {
2329 return false;
2330 }
2331 } else {
2332 return false;
2333 }
2334 }
2335 return true;
2336 }
2337
2338 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2339 // Ensure a use outside of loop is of the right form
2340 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2341 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2342 return (use->is_Phi() &&
2343 use_c->is_Region() && use_c->req() == 3 &&
2344 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2345 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2346 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2347 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2348 }
2349
2350 //------------------------------ is_valid_clone_loop_form -------------------------------------
2351 // Ensure that all uses outside of loop are of the right form
2352 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2353 uint orig_exit_idx, uint clone_exit_idx) {
2354 uint len = peel_list.size();
2355 for (uint i = 0; i < len; i++) {
2356 Node *def = peel_list.at(i);
2357
2358 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2359 Node *use = def->fast_out(j);
2360 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2361 if (!loop->is_member(get_loop(use_c))) {
2362 // use is not in the loop, check for correct structure
2363 if (use->in(0) == def) {
2364 // Okay
2365 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2366 return false;
2367 }
2368 }
2369 }
2370 }
2371 return true;
2372 }
2373 #endif
2374
2375 //------------------------------ partial_peel -------------------------------------
2376 // Partially peel (aka loop rotation) the top portion of a loop (called
2377 // the peel section below) by cloning it and placing one copy just before
2378 // the new loop head and the other copy at the bottom of the new loop.
2379 //
2380 // before after where it came from
2381 //
2382 // stmt1 stmt1
2383 // loop: stmt2 clone
2384 // stmt2 if condA goto exitA clone
2385 // if condA goto exitA new_loop: new
2386 // stmt3 stmt3 clone
2387 // if !condB goto loop if condB goto exitB clone
2388 // exitB: stmt2 orig
2389 // stmt4 if !condA goto new_loop orig
2390 // exitA: goto exitA
2391 // exitB:
2392 // stmt4
2393 // exitA:
2394 //
2395 // Step 1: find the cut point: an exit test on probable
2396 // induction variable.
2397 // Step 2: schedule (with cloning) operations in the peel
2398 // section that can be executed after the cut into
2399 // the section that is not peeled. This may need
2400 // to clone operations into exit blocks. For
2401 // instance, a reference to A[i] in the not-peel
2402 // section and a reference to B[i] in an exit block
2403 // may cause a left-shift of i by 2 to be placed
2404 // in the peel block. This step will clone the left
2405 // shift into the exit block and sink the left shift
2406 // from the peel to the not-peel section.
2407 // Step 3: clone the loop, retarget the control, and insert
2408 // phis for values that are live across the new loop
2409 // head. This is very dependent on the graph structure
2410 // from clone_loop. It creates region nodes for
2411 // exit control and associated phi nodes for values
2412 // flow out of the loop through that exit. The region
2413 // node is dominated by the clone's control projection.
2414 // So the clone's peel section is placed before the
2415 // new loop head, and the clone's not-peel section is
2416 // forms the top part of the new loop. The original
2417 // peel section forms the tail of the new loop.
2418 // Step 4: update the dominator tree and recompute the
2419 // dominator depth.
2420 //
2421 // orig
2422 //
2423 // stmt1
2424 // |
2425 // v
2426 // loop predicate
2427 // |
2428 // v
2429 // loop<----+
2430 // | |
2431 // stmt2 |
2432 // | |
2433 // v |
2434 // ifA |
2435 // / | |
2436 // v v |
2437 // false true ^ <-- last_peel
2438 // / | |
2439 // / ===|==cut |
2440 // / stmt3 | <-- first_not_peel
2441 // / | |
2442 // | v |
2443 // v ifB |
2444 // exitA: / \ |
2445 // / \ |
2446 // v v |
2447 // false true |
2448 // / \ |
2449 // / ----+
2450 // |
2451 // v
2452 // exitB:
2453 // stmt4
2454 //
2455 //
2456 // after clone loop
2457 //
2458 // stmt1
2459 // |
2460 // v
2461 // loop predicate
2462 // / \
2463 // clone / \ orig
2464 // / \
2465 // / \
2466 // v v
2467 // +---->loop loop<----+
2468 // | | | |
2469 // | stmt2 stmt2 |
2470 // | | | |
2471 // | v v |
2472 // | ifA ifA |
2473 // | | \ / | |
2474 // | v v v v |
2475 // ^ true false false true ^ <-- last_peel
2476 // | | ^ \ / | |
2477 // | cut==|== \ \ / ===|==cut |
2478 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2479 // | | dom | | | |
2480 // | v \ 1v v2 v |
2481 // | ifB regionA ifB |
2482 // | / \ | / \ |
2483 // | / \ v / \ |
2484 // | v v exitA: v v |
2485 // | true false false true |
2486 // | / ^ \ / \ |
2487 // +---- \ \ / ----+
2488 // dom \ /
2489 // \ 1v v2
2490 // regionB
2491 // |
2492 // v
2493 // exitB:
2494 // stmt4
2495 //
2496 //
2497 // after partial peel
2498 //
2499 // stmt1
2500 // |
2501 // v
2502 // loop predicate
2503 // /
2504 // clone / orig
2505 // / TOP
2506 // / \
2507 // v v
2508 // TOP->loop loop----+
2509 // | | |
2510 // stmt2 stmt2 |
2511 // | | |
2512 // v v |
2513 // ifA ifA |
2514 // | \ / | |
2515 // v v v v |
2516 // true false false true | <-- last_peel
2517 // | ^ \ / +------|---+
2518 // +->newloop \ \ / === ==cut | |
2519 // | stmt3 \ \ / TOP | |
2520 // | | dom | | stmt3 | | <-- first_not_peel
2521 // | v \ 1v v2 v | |
2522 // | ifB regionA ifB ^ v
2523 // | / \ | / \ | |
2524 // | / \ v / \ | |
2525 // | v v exitA: v v | |
2526 // | true false false true | |
2527 // | / ^ \ / \ | |
2528 // | | \ \ / v | |
2529 // | | dom \ / TOP | |
2530 // | | \ 1v v2 | |
2531 // ^ v regionB | |
2532 // | | | | |
2533 // | | v ^ v
2534 // | | exitB: | |
2535 // | | stmt4 | |
2536 // | +------------>-----------------+ |
2537 // | |
2538 // +-----------------<---------------------+
2539 //
2540 //
2541 // final graph
2542 //
2543 // stmt1
2544 // |
2545 // v
2546 // loop predicate
2547 // |
2548 // v
2549 // stmt2 clone
2550 // |
2551 // v
2552 // ........> ifA clone
2553 // : / |
2554 // dom / |
2555 // : v v
2556 // : false true
2557 // : | |
2558 // : | v
2559 // : | newloop<-----+
2560 // : | | |
2561 // : | stmt3 clone |
2562 // : | | |
2563 // : | v |
2564 // : | ifB |
2565 // : | / \ |
2566 // : | v v |
2567 // : | false true |
2568 // : | | | |
2569 // : | v stmt2 |
2570 // : | exitB: | |
2571 // : | stmt4 v |
2572 // : | ifA orig |
2573 // : | / \ |
2574 // : | / \ |
2575 // : | v v |
2576 // : | false true |
2577 // : | / \ |
2578 // : v v -----+
2579 // RegionA
2580 // |
2581 // v
2582 // exitA
2583 //
2584 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2585
2586 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2587 if (!loop->_head->is_Loop()) {
2588 return false; }
2589
2590 LoopNode *head = loop->_head->as_Loop();
2591
2592 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2593 return false;
2594 }
2595
2596 // Check for complex exit control
2597 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2598 Node *n = loop->_body.at(ii);
2599 int opc = n->Opcode();
2600 if (n->is_Call() ||
2601 opc == Op_Catch ||
2602 opc == Op_CatchProj ||
2603 opc == Op_Jump ||
2604 opc == Op_JumpProj) {
2605 #if !defined(PRODUCT)
2606 if (TracePartialPeeling) {
2607 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2608 }
2609 #endif
2610 return false;
2611 }
2612 }
2613
2614 int dd = dom_depth(head);
2615
2616 // Step 1: find cut point
2617
2618 // Walk up dominators to loop head looking for first loop exit
2619 // which is executed on every path thru loop.
2620 IfNode *peel_if = NULL;
2621 IfNode *peel_if_cmpu = NULL;
2622
2623 Node *iff = loop->tail();
2624 while( iff != head ) {
2625 if( iff->is_If() ) {
2626 Node *ctrl = get_ctrl(iff->in(1));
2627 if (ctrl->is_top()) return false; // Dead test on live IF.
2628 // If loop-varying exit-test, check for induction variable
2629 if( loop->is_member(get_loop(ctrl)) &&
2630 loop->is_loop_exit(iff) &&
2631 is_possible_iv_test(iff)) {
2632 Node* cmp = iff->in(1)->in(1);
2633 if (cmp->Opcode() == Op_CmpI) {
2634 peel_if = iff->as_If();
2635 } else {
2636 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2637 peel_if_cmpu = iff->as_If();
2638 }
2639 }
2640 }
2641 iff = idom(iff);
2642 }
2643 // Prefer signed compare over unsigned compare.
2644 IfNode* new_peel_if = NULL;
2645 if (peel_if == NULL) {
2646 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2647 return false; // No peel point found
2648 }
2649 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2650 if (new_peel_if == NULL) {
2651 return false; // No peel point found
2652 }
2653 peel_if = new_peel_if;
2654 }
2655 Node* last_peel = stay_in_loop(peel_if, loop);
2656 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2657 if (first_not_peeled == NULL || first_not_peeled == head) {
2658 return false;
2659 }
2660
2661 #if !defined(PRODUCT)
2662 if (TraceLoopOpts) {
2663 tty->print("PartialPeel ");
2664 loop->dump_head();
2665 }
2666
2667 if (TracePartialPeeling) {
2668 tty->print_cr("before partial peel one iteration");
2669 Node_List wl;
2670 Node* t = head->in(2);
2671 while (true) {
2672 wl.push(t);
2673 if (t == head) break;
2674 t = idom(t);
2675 }
2676 while (wl.size() > 0) {
2677 Node* tt = wl.pop();
2678 tt->dump();
2679 if (tt == last_peel) tty->print_cr("-- cut --");
2680 }
2681 }
2682 #endif
2683 ResourceArea *area = Thread::current()->resource_area();
2684 VectorSet peel(area);
2685 VectorSet not_peel(area);
2686 Node_List peel_list(area);
2687 Node_List worklist(area);
2688 Node_List sink_list(area);
2689
2690 // Set of cfg nodes to peel are those that are executable from
2691 // the head through last_peel.
2692 assert(worklist.size() == 0, "should be empty");
2693 worklist.push(head);
2694 peel.set(head->_idx);
2695 while (worklist.size() > 0) {
2696 Node *n = worklist.pop();
2697 if (n != last_peel) {
2698 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2699 Node* use = n->fast_out(j);
2700 if (use->is_CFG() &&
2701 loop->is_member(get_loop(use)) &&
2702 !peel.test_set(use->_idx)) {
2703 worklist.push(use);
2704 }
2705 }
2706 }
2707 }
2708
2709 // Set of non-cfg nodes to peel are those that are control
2710 // dependent on the cfg nodes.
2711 uint i;
2712 for(i = 0; i < loop->_body.size(); i++ ) {
2713 Node *n = loop->_body.at(i);
2714 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2715 if (peel.test(n_c->_idx)) {
2716 peel.set(n->_idx);
2717 } else {
2718 not_peel.set(n->_idx);
2719 }
2720 }
2721
2722 // Step 2: move operations from the peeled section down into the
2723 // not-peeled section
2724
2725 // Get a post order schedule of nodes in the peel region
2726 // Result in right-most operand.
2727 scheduled_nodelist(loop, peel, peel_list );
2728
2729 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2730
2731 // For future check for too many new phis
2732 uint old_phi_cnt = 0;
2733 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2734 Node* use = head->fast_out(j);
2735 if (use->is_Phi()) old_phi_cnt++;
2736 }
2737
2738 #if !defined(PRODUCT)
2739 if (TracePartialPeeling) {
2740 tty->print_cr("\npeeled list");
2741 }
2742 #endif
2743
2744 // Evacuate nodes in peel region into the not_peeled region if possible
2745 uint new_phi_cnt = 0;
2746 uint cloned_for_outside_use = 0;
2747 for (i = 0; i < peel_list.size();) {
2748 Node* n = peel_list.at(i);
2749 #if !defined(PRODUCT)
2750 if (TracePartialPeeling) n->dump();
2751 #endif
2752 bool incr = true;
2753 if ( !n->is_CFG() ) {
2754
2755 if ( has_use_in_set(n, not_peel) ) {
2756
2757 // If not used internal to the peeled region,
2758 // move "n" from peeled to not_peeled region.
2759
2760 if ( !has_use_internal_to_set(n, peel, loop) ) {
2761
2762 // if not pinned and not a load (which maybe anti-dependent on a store)
2763 // and not a CMove (Matcher expects only bool->cmove).
2764 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2765 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2766 sink_list.push(n);
2767 peel >>= n->_idx; // delete n from peel set.
2768 not_peel <<= n->_idx; // add n to not_peel set.
2769 peel_list.remove(i);
2770 incr = false;
2771 #if !defined(PRODUCT)
2772 if (TracePartialPeeling) {
2773 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2774 n->_idx, get_ctrl(n)->_idx);
2775 }
2776 #endif
2777 }
2778 } else {
2779 // Otherwise check for special def-use cases that span
2780 // the peel/not_peel boundary such as bool->if
2781 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2782 new_phi_cnt++;
2783 }
2784 }
2785 }
2786 if (incr) i++;
2787 }
2788
2789 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2790 #if !defined(PRODUCT)
2791 if (TracePartialPeeling) {
2792 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2793 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2794 }
2795 #endif
2796 if (new_peel_if != NULL) {
2797 remove_cmpi_loop_exit(new_peel_if, loop);
2798 }
2799 // Inhibit more partial peeling on this loop
2800 assert(!head->is_partial_peel_loop(), "not partial peeled");
2801 head->mark_partial_peel_failed();
2802 if (cloned_for_outside_use > 0) {
2803 // Terminate this round of loop opts because
2804 // the graph outside this loop was changed.
2805 C->set_major_progress();
2806 return true;
2807 }
2808 return false;
2809 }
2810
2811 // Step 3: clone loop, retarget control, and insert new phis
2812
2813 // Create new loop head for new phis and to hang
2814 // the nodes being moved (sinked) from the peel region.
2815 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2816 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2817 _igvn.register_new_node_with_optimizer(new_head);
2818 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2819 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2820 set_loop(new_head, loop);
2821 loop->_body.push(new_head);
2822 not_peel.set(new_head->_idx);
2823 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2824 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2825
2826 while (sink_list.size() > 0) {
2827 Node* n = sink_list.pop();
2828 set_ctrl(n, new_head);
2829 }
2830
2831 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2832
2833 clone_loop( loop, old_new, dd );
2834
2835 const uint clone_exit_idx = 1;
2836 const uint orig_exit_idx = 2;
2837 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2838
2839 Node* head_clone = old_new[head->_idx];
2840 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2841 Node* orig_tail_clone = head_clone->in(2);
2842
2843 // Add phi if "def" node is in peel set and "use" is not
2844
2845 for(i = 0; i < peel_list.size(); i++ ) {
2846 Node *def = peel_list.at(i);
2847 if (!def->is_CFG()) {
2848 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2849 Node *use = def->fast_out(j);
2850 if (has_node(use) && use->in(0) != C->top() &&
2851 (!peel.test(use->_idx) ||
2852 (use->is_Phi() && use->in(0) == head)) ) {
2853 worklist.push(use);
2854 }
2855 }
2856 while( worklist.size() ) {
2857 Node *use = worklist.pop();
2858 for (uint j = 1; j < use->req(); j++) {
2859 Node* n = use->in(j);
2860 if (n == def) {
2861
2862 // "def" is in peel set, "use" is not in peel set
2863 // or "use" is in the entry boundary (a phi) of the peel set
2864
2865 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2866
2867 if ( loop->is_member(get_loop( use_c )) ) {
2868 // use is in loop
2869 if (old_new[use->_idx] != NULL) { // null for dead code
2870 Node* use_clone = old_new[use->_idx];
2871 _igvn.replace_input_of(use, j, C->top());
2872 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2873 }
2874 } else {
2875 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2876 // use is not in the loop, check if the live range includes the cut
2877 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2878 if (not_peel.test(lp_if->_idx)) {
2879 assert(j == orig_exit_idx, "use from original loop");
2880 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2881 }
2882 }
2883 }
2884 }
2885 }
2886 }
2887 }
2888
2889 // Step 3b: retarget control
2890
2891 // Redirect control to the new loop head if a cloned node in
2892 // the not_peeled region has control that points into the peeled region.
2893 // This necessary because the cloned peeled region will be outside
2894 // the loop.
2895 // from to
2896 // cloned-peeled <---+
2897 // new_head_clone: | <--+
2898 // cloned-not_peeled in(0) in(0)
2899 // orig-peeled
2900
2901 for(i = 0; i < loop->_body.size(); i++ ) {
2902 Node *n = loop->_body.at(i);
2903 if (!n->is_CFG() && n->in(0) != NULL &&
2904 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2905 Node* n_clone = old_new[n->_idx];
2906 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2907 }
2908 }
2909
2910 // Backedge of the surviving new_head (the clone) is original last_peel
2911 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2912
2913 // Cut first node in original not_peel set
2914 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2915 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2916 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2917
2918 // Copy head_clone back-branch info to original head
2919 // and remove original head's loop entry and
2920 // clone head's back-branch
2921 _igvn.rehash_node_delayed(head); // Multiple edge updates
2922 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2923 head->set_req(LoopNode::LoopBackControl, C->top());
2924 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2925
2926 // Similarly modify the phis
2927 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2928 Node* use = head->fast_out(k);
2929 if (use->is_Phi() && use->outcnt() > 0) {
2930 Node* use_clone = old_new[use->_idx];
2931 _igvn.rehash_node_delayed(use); // Multiple edge updates
2932 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2933 use->set_req(LoopNode::LoopBackControl, C->top());
2934 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2935 }
2936 }
2937
2938 // Step 4: update dominator tree and dominator depth
2939
2940 set_idom(head, orig_tail_clone, dd);
2941 recompute_dom_depth();
2942
2943 // Inhibit more partial peeling on this loop
2944 new_head_clone->set_partial_peel_loop();
2945 C->set_major_progress();
2946 loop->record_for_igvn();
2947
2948 #if !defined(PRODUCT)
2949 if (TracePartialPeeling) {
2950 tty->print_cr("\nafter partial peel one iteration");
2951 Node_List wl(area);
2952 Node* t = last_peel;
2953 while (true) {
2954 wl.push(t);
2955 if (t == head_clone) break;
2956 t = idom(t);
2957 }
2958 while (wl.size() > 0) {
2959 Node* tt = wl.pop();
2960 if (tt == head) tty->print_cr("orig head");
2961 else if (tt == new_head_clone) tty->print_cr("new head");
2962 else if (tt == head_clone) tty->print_cr("clone head");
2963 tt->dump();
2964 }
2965 }
2966 #endif
2967 return true;
2968 }
2969
2970 //------------------------------reorg_offsets----------------------------------
2971 // Reorganize offset computations to lower register pressure. Mostly
2972 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2973 // then alive with the post-incremented trip counter forcing an extra
2974 // register move)
2975 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2976 // Perform it only for canonical counted loops.
2977 // Loop's shape could be messed up by iteration_split_impl.
2978 if (!loop->_head->is_CountedLoop())
2979 return;
2980 if (!loop->_head->as_Loop()->is_valid_counted_loop())
2981 return;
2982
2983 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2984 CountedLoopEndNode *cle = cl->loopexit();
2985 Node *exit = cle->proj_out(false);
2986 Node *phi = cl->phi();
2987
2988 // Check for the special case of folks using the pre-incremented
2989 // trip-counter on the fall-out path (forces the pre-incremented
2990 // and post-incremented trip counter to be live at the same time).
2991 // Fix this by adjusting to use the post-increment trip counter.
2992
2993 bool progress = true;
2994 while (progress) {
2995 progress = false;
2996 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
2997 Node* use = phi->fast_out(i); // User of trip-counter
2998 if (!has_ctrl(use)) continue;
2999 Node *u_ctrl = get_ctrl(use);
3000 if (use->is_Phi()) {
3001 u_ctrl = NULL;
3002 for (uint j = 1; j < use->req(); j++)
3003 if (use->in(j) == phi)
3004 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3005 }
3006 IdealLoopTree *u_loop = get_loop(u_ctrl);
3007 // Look for loop-invariant use
3008 if (u_loop == loop) continue;
3009 if (loop->is_member(u_loop)) continue;
3010 // Check that use is live out the bottom. Assuming the trip-counter
3011 // update is right at the bottom, uses of of the loop middle are ok.
3012 if (dom_lca(exit, u_ctrl) != exit) continue;
3013 // Hit! Refactor use to use the post-incremented tripcounter.
3014 // Compute a post-increment tripcounter.
3015 Node *opaq = new Opaque2Node( C, cle->incr() );
3016 register_new_node(opaq, exit);
3017 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3018 set_ctrl(neg_stride, C->root());
3019 Node *post = new AddINode( opaq, neg_stride);
3020 register_new_node(post, exit);
3021 _igvn.rehash_node_delayed(use);
3022 for (uint j = 1; j < use->req(); j++) {
3023 if (use->in(j) == phi)
3024 use->set_req(j, post);
3025 }
3026 // Since DU info changed, rerun loop
3027 progress = true;
3028 break;
3029 }
3030 }
3031
3032 }