1 /*
2 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/connode.hpp"
29 #include "opto/divnode.hpp"
30 #include "opto/loopnode.hpp"
31 #include "opto/matcher.hpp"
32 #include "opto/mulnode.hpp"
33 #include "opto/movenode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37
38 //=============================================================================
39 //------------------------------split_thru_phi---------------------------------
40 // Split Node 'n' through merge point if there is enough win.
41 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
42 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
43 // ConvI2L may have type information on it which is unsafe to push up
44 // so disable this for now
45 return NULL;
46 }
47
48 int wins = 0;
49 assert(!n->is_CFG(), "");
50 assert(region->is_Region(), "");
51
52 const Type* type = n->bottom_type();
53 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
54 Node *phi;
55 if (t_oop != NULL && t_oop->is_known_instance_field()) {
56 int iid = t_oop->instance_id();
57 int index = C->get_alias_index(t_oop);
58 int offset = t_oop->offset();
59 phi = new PhiNode(region, type, NULL, iid, index, offset);
60 } else {
61 phi = PhiNode::make_blank(region, n);
62 }
63 uint old_unique = C->unique();
64 for (uint i = 1; i < region->req(); i++) {
65 Node *x;
66 Node* the_clone = NULL;
67 if (region->in(i) == C->top()) {
68 x = C->top(); // Dead path? Use a dead data op
69 } else {
70 x = n->clone(); // Else clone up the data op
71 the_clone = x; // Remember for possible deletion.
72 // Alter data node to use pre-phi inputs
73 if (n->in(0) == region)
74 x->set_req( 0, region->in(i) );
75 for (uint j = 1; j < n->req(); j++) {
76 Node *in = n->in(j);
77 if (in->is_Phi() && in->in(0) == region)
78 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
79 }
80 }
81 // Check for a 'win' on some paths
82 const Type *t = x->Value(&_igvn);
83
84 bool singleton = t->singleton();
85
86 // A TOP singleton indicates that there are no possible values incoming
87 // along a particular edge. In most cases, this is OK, and the Phi will
88 // be eliminated later in an Ideal call. However, we can't allow this to
89 // happen if the singleton occurs on loop entry, as the elimination of
90 // the PhiNode may cause the resulting node to migrate back to a previous
91 // loop iteration.
92 if (singleton && t == Type::TOP) {
93 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
94 // irreducible loop may not be indicated by an affirmative is_Loop());
95 // therefore, the only top we can split thru a phi is on a backedge of
96 // a loop.
97 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
98 }
99
100 if (singleton) {
101 wins++;
102 x = ((PhaseGVN&)_igvn).makecon(t);
103 } else {
104 // We now call Identity to try to simplify the cloned node.
105 // Note that some Identity methods call phase->type(this).
106 // Make sure that the type array is big enough for
107 // our new node, even though we may throw the node away.
108 // (Note: This tweaking with igvn only works because x is a new node.)
109 _igvn.set_type(x, t);
110 // If x is a TypeNode, capture any more-precise type permanently into Node
111 // otherwise it will be not updated during igvn->transform since
112 // igvn->type(x) is set to x->Value() already.
113 x->raise_bottom_type(t);
114 Node *y = x->Identity(&_igvn);
115 if (y != x) {
116 wins++;
117 x = y;
118 } else {
119 y = _igvn.hash_find(x);
120 if (y) {
121 wins++;
122 x = y;
123 } else {
124 // Else x is a new node we are keeping
125 // We do not need register_new_node_with_optimizer
126 // because set_type has already been called.
127 _igvn._worklist.push(x);
128 }
129 }
130 }
131 if (x != the_clone && the_clone != NULL)
132 _igvn.remove_dead_node(the_clone);
133 phi->set_req( i, x );
134 }
135 // Too few wins?
136 if (wins <= policy) {
137 _igvn.remove_dead_node(phi);
138 return NULL;
139 }
140
141 // Record Phi
142 register_new_node( phi, region );
143
144 for (uint i2 = 1; i2 < phi->req(); i2++) {
145 Node *x = phi->in(i2);
146 // If we commoned up the cloned 'x' with another existing Node,
147 // the existing Node picks up a new use. We need to make the
148 // existing Node occur higher up so it dominates its uses.
149 Node *old_ctrl;
150 IdealLoopTree *old_loop;
151
152 if (x->is_Con()) {
153 // Constant's control is always root.
154 set_ctrl(x, C->root());
155 continue;
156 }
157 // The occasional new node
158 if (x->_idx >= old_unique) { // Found a new, unplaced node?
159 old_ctrl = NULL;
160 old_loop = NULL; // Not in any prior loop
161 } else {
162 old_ctrl = get_ctrl(x);
163 old_loop = get_loop(old_ctrl); // Get prior loop
164 }
165 // New late point must dominate new use
166 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
167 if (new_ctrl == old_ctrl) // Nothing is changed
168 continue;
169
170 IdealLoopTree *new_loop = get_loop(new_ctrl);
171
172 // Don't move x into a loop if its uses are
173 // outside of loop. Otherwise x will be cloned
174 // for each use outside of this loop.
175 IdealLoopTree *use_loop = get_loop(region);
176 if (!new_loop->is_member(use_loop) &&
177 (old_loop == NULL || !new_loop->is_member(old_loop))) {
178 // Take early control, later control will be recalculated
179 // during next iteration of loop optimizations.
180 new_ctrl = get_early_ctrl(x);
181 new_loop = get_loop(new_ctrl);
182 }
183 // Set new location
184 set_ctrl(x, new_ctrl);
185 // If changing loop bodies, see if we need to collect into new body
186 if (old_loop != new_loop) {
187 if (old_loop && !old_loop->_child)
188 old_loop->_body.yank(x);
189 if (!new_loop->_child)
190 new_loop->_body.push(x); // Collect body info
191 }
192 }
193
194 return phi;
195 }
196
197 //------------------------------dominated_by------------------------------------
198 // Replace the dominated test with an obvious true or false. Place it on the
199 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
200 // live path up to the dominating control.
201 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
202 #ifndef PRODUCT
203 if (VerifyLoopOptimizations && PrintOpto) tty->print_cr("dominating test");
204 #endif
205
206
207 // prevdom is the dominating projection of the dominating test.
208 assert( iff->is_If(), "" );
209 assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
210 int pop = prevdom->Opcode();
211 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
212 if (flip) {
213 if (pop == Op_IfTrue)
214 pop = Op_IfFalse;
215 else
216 pop = Op_IfTrue;
217 }
218 // 'con' is set to true or false to kill the dominated test.
219 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
220 set_ctrl(con, C->root()); // Constant gets a new use
221 // Hack the dominated test
222 _igvn.replace_input_of(iff, 1, con);
223
224 // If I dont have a reachable TRUE and FALSE path following the IfNode then
225 // I can assume this path reaches an infinite loop. In this case it's not
226 // important to optimize the data Nodes - either the whole compilation will
227 // be tossed or this path (and all data Nodes) will go dead.
228 if (iff->outcnt() != 2) return;
229
230 // Make control-dependent data Nodes on the live path (path that will remain
231 // once the dominated IF is removed) become control-dependent on the
232 // dominating projection.
233 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
234
235 // Loop predicates may have depending checks which should not
236 // be skipped. For example, range check predicate has two checks
237 // for lower and upper bounds.
238 if (dp == NULL)
239 return;
240
241 ProjNode* dp_proj = dp->as_Proj();
242 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
243 if (exclude_loop_predicate &&
244 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
245 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
246 // If this is a range check (IfNode::is_range_check), do not
247 // reorder because Compile::allow_range_check_smearing might have
248 // changed the check.
249 return; // Let IGVN transformation change control dependence.
250 }
251
252 IdealLoopTree *old_loop = get_loop(dp);
253
254 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
255 Node* cd = dp->fast_out(i); // Control-dependent node
256 if (cd->depends_only_on_test()) {
257 assert(cd->in(0) == dp, "");
258 _igvn.replace_input_of(cd, 0, prevdom);
259 set_early_ctrl(cd);
260 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
261 if (old_loop != new_loop) {
262 if (!old_loop->_child) old_loop->_body.yank(cd);
263 if (!new_loop->_child) new_loop->_body.push(cd);
264 }
265 --i;
266 --imax;
267 }
268 }
269 }
270
271 //------------------------------has_local_phi_input----------------------------
272 // Return TRUE if 'n' has Phi inputs from its local block and no other
273 // block-local inputs (all non-local-phi inputs come from earlier blocks)
274 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
275 Node *n_ctrl = get_ctrl(n);
276 // See if some inputs come from a Phi in this block, or from before
277 // this block.
278 uint i;
279 for( i = 1; i < n->req(); i++ ) {
280 Node *phi = n->in(i);
281 if( phi->is_Phi() && phi->in(0) == n_ctrl )
282 break;
283 }
284 if( i >= n->req() )
285 return NULL; // No Phi inputs; nowhere to clone thru
286
287 // Check for inputs created between 'n' and the Phi input. These
288 // must split as well; they have already been given the chance
289 // (courtesy of a post-order visit) and since they did not we must
290 // recover the 'cost' of splitting them by being very profitable
291 // when splitting 'n'. Since this is unlikely we simply give up.
292 for( i = 1; i < n->req(); i++ ) {
293 Node *m = n->in(i);
294 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
295 // We allow the special case of AddP's with no local inputs.
296 // This allows us to split-up address expressions.
297 if (m->is_AddP() &&
298 get_ctrl(m->in(2)) != n_ctrl &&
299 get_ctrl(m->in(3)) != n_ctrl) {
300 // Move the AddP up to dominating point
301 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
302 continue;
303 }
304 return NULL;
305 }
306 }
307
308 return n_ctrl;
309 }
310
311 //------------------------------remix_address_expressions----------------------
312 // Rework addressing expressions to get the most loop-invariant stuff
313 // moved out. We'd like to do all associative operators, but it's especially
314 // important (common) to do address expressions.
315 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
316 if (!has_ctrl(n)) return NULL;
317 Node *n_ctrl = get_ctrl(n);
318 IdealLoopTree *n_loop = get_loop(n_ctrl);
319
320 // See if 'n' mixes loop-varying and loop-invariant inputs and
321 // itself is loop-varying.
322
323 // Only interested in binary ops (and AddP)
324 if( n->req() < 3 || n->req() > 4 ) return NULL;
325
326 Node *n1_ctrl = get_ctrl(n->in( 1));
327 Node *n2_ctrl = get_ctrl(n->in( 2));
328 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
329 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
330 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
331 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
332
333 // Does one of my inputs spin in a tighter loop than self?
334 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
335 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
336 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
337 return NULL; // Leave well enough alone
338
339 // Is at least one of my inputs loop-invariant?
340 if( n1_loop == n_loop &&
341 n2_loop == n_loop &&
342 n3_loop == n_loop )
343 return NULL; // No loop-invariant inputs
344
345
346 int n_op = n->Opcode();
347
348 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
349 if( n_op == Op_LShiftI ) {
350 // Scale is loop invariant
351 Node *scale = n->in(2);
352 Node *scale_ctrl = get_ctrl(scale);
353 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
354 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
355 return NULL;
356 const TypeInt *scale_t = scale->bottom_type()->isa_int();
357 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
358 return NULL; // Dont bother with byte/short masking
359 // Add must vary with loop (else shift would be loop-invariant)
360 Node *add = n->in(1);
361 Node *add_ctrl = get_ctrl(add);
362 IdealLoopTree *add_loop = get_loop(add_ctrl);
363 //assert( n_loop == add_loop, "" );
364 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
365
366 // Convert I-V into I+ (0-V); same for V-I
367 if( add->Opcode() == Op_SubI &&
368 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
369 Node *zero = _igvn.intcon(0);
370 set_ctrl(zero, C->root());
371 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
372 register_new_node( neg, get_ctrl(add->in(2) ) );
373 add = new AddINode( add->in(1), neg );
374 register_new_node( add, add_ctrl );
375 }
376 if( add->Opcode() != Op_AddI ) return NULL;
377 // See if one add input is loop invariant
378 Node *add_var = add->in(1);
379 Node *add_var_ctrl = get_ctrl(add_var);
380 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
381 Node *add_invar = add->in(2);
382 Node *add_invar_ctrl = get_ctrl(add_invar);
383 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
384 if( add_var_loop == n_loop ) {
385 } else if( add_invar_loop == n_loop ) {
386 // Swap to find the invariant part
387 add_invar = add_var;
388 add_invar_ctrl = add_var_ctrl;
389 add_invar_loop = add_var_loop;
390 add_var = add->in(2);
391 Node *add_var_ctrl = get_ctrl(add_var);
392 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
393 } else // Else neither input is loop invariant
394 return NULL;
395 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
396 return NULL; // No invariant part of the add?
397
398 // Yes! Reshape address expression!
399 Node *inv_scale = new LShiftINode( add_invar, scale );
400 Node *inv_scale_ctrl =
401 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
402 add_invar_ctrl : scale_ctrl;
403 register_new_node( inv_scale, inv_scale_ctrl );
404 Node *var_scale = new LShiftINode( add_var, scale );
405 register_new_node( var_scale, n_ctrl );
406 Node *var_add = new AddINode( var_scale, inv_scale );
407 register_new_node( var_add, n_ctrl );
408 _igvn.replace_node( n, var_add );
409 return var_add;
410 }
411
412 // Replace (I+V) with (V+I)
413 if( n_op == Op_AddI ||
414 n_op == Op_AddL ||
415 n_op == Op_AddF ||
416 n_op == Op_AddD ||
417 n_op == Op_MulI ||
418 n_op == Op_MulL ||
419 n_op == Op_MulF ||
420 n_op == Op_MulD ) {
421 if( n2_loop == n_loop ) {
422 assert( n1_loop != n_loop, "" );
423 n->swap_edges(1, 2);
424 }
425 }
426
427 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
428 // but not if I2 is a constant.
429 if( n_op == Op_AddP ) {
430 if( n2_loop == n_loop && n3_loop != n_loop ) {
431 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
432 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
433 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
434 IdealLoopTree *n22loop = get_loop( n22_ctrl );
435 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
436 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
437 n23_loop == n_loop ) {
438 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
439 // Stuff new AddP in the loop preheader
440 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
441 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
442 register_new_node( add2, n_ctrl );
443 _igvn.replace_node( n, add2 );
444 return add2;
445 }
446 }
447 }
448
449 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
450 if (n2_loop != n_loop && n3_loop == n_loop) {
451 if (n->in(3)->Opcode() == Op_AddX) {
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 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
657 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
658 Node* u = m->fast_out(i);
659 if (u->is_CFG()) {
660 if (u->Opcode() == Op_NeverBranch) {
661 u = ((NeverBranchNode*)u)->proj_out(0);
662 enqueue_cfg_uses(u, wq);
663 } else {
664 wq.push(u);
665 }
666 }
667 }
668 }
669
670 // Try moving a store out of a loop, right before the loop
671 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
672 // Store has to be first in the loop body
673 IdealLoopTree *n_loop = get_loop(n_ctrl);
674 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
675 Node* address = n->in(MemNode::Address);
676 Node* value = n->in(MemNode::ValueIn);
677 Node* mem = n->in(MemNode::Memory);
678 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
679 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
680
681 // - address and value must be loop invariant
682 // - memory must be a memory Phi for the loop
683 // - Store must be the only store on this memory slice in the
684 // loop: if there's another store following this one then value
685 // written at iteration i by the second store could be overwritten
686 // at iteration i+n by the first store: it's not safe to move the
687 // first store out of the loop
688 // - nothing must observe the memory Phi: it guarantees no read
689 // before the store, we are also guaranteed the store post
690 // dominates the loop head (ignoring a possible early
691 // exit). Otherwise there would be extra Phi involved between the
692 // loop's Phi and the store.
693 // - there must be no early exit from the loop before the Store
694 // (such an exit most of the time would be an extra use of the
695 // memory Phi but sometimes is a bottom memory Phi that takes the
696 // store as input).
697
698 if (!n_loop->is_member(address_loop) &&
699 !n_loop->is_member(value_loop) &&
700 mem->is_Phi() && mem->in(0) == n_loop->_head &&
701 mem->outcnt() == 1 &&
702 mem->in(LoopNode::LoopBackControl) == n) {
703
704 assert(n_loop->_tail != NULL, "need a tail");
705 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
706
707 // Verify that there's no early exit of the loop before the store.
708 bool ctrl_ok = false;
709 {
710 // Follow control from loop head until n, we exit the loop or
711 // we reach the tail
712 ResourceMark rm;
713 Unique_Node_List wq;
714 wq.push(n_loop->_head);
715
716 for (uint next = 0; next < wq.size(); ++next) {
717 Node *m = wq.at(next);
718 if (m == n->in(0)) {
719 ctrl_ok = true;
720 continue;
721 }
722 assert(!has_ctrl(m), "should be CFG");
723 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
724 ctrl_ok = false;
725 break;
726 }
727 enqueue_cfg_uses(m, wq);
728 if (wq.size() > 10) {
729 ctrl_ok = false;
730 break;
731 }
732 }
733 }
734 if (ctrl_ok) {
735 // move the Store
736 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
737 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
738 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
739 // Disconnect the phi now. An empty phi can confuse other
740 // optimizations in this pass of loop opts.
741 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
742 n_loop->_body.yank(mem);
743
744 IdealLoopTree* new_loop = get_loop(n->in(0));
745 set_ctrl_and_loop(n, n->in(0));
746
747 return n;
748 }
749 }
750 }
751 return NULL;
752 }
753
754 // Try moving a store out of a loop, right after the loop
755 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
756 if (n->is_Store() && n->in(0) != NULL) {
757 Node *n_ctrl = get_ctrl(n);
758 IdealLoopTree *n_loop = get_loop(n_ctrl);
759 // Store must be in a loop
760 if (n_loop != _ltree_root && !n_loop->_irreducible) {
761 Node* address = n->in(MemNode::Address);
762 Node* value = n->in(MemNode::ValueIn);
763 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
764 // address must be loop invariant
765 if (!n_loop->is_member(address_loop)) {
766 // Store must be last on this memory slice in the loop and
767 // nothing in the loop must observe it
768 Node* phi = NULL;
769 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
770 Node* u = n->fast_out(i);
771 if (has_ctrl(u)) { // control use?
772 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
773 if (!n_loop->is_member(u_loop)) {
774 continue;
775 }
776 if (u->is_Phi() && u->in(0) == n_loop->_head) {
777 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
778 // multiple phis on the same slice are possible
779 if (phi != NULL) {
780 return;
781 }
782 phi = u;
783 continue;
784 }
785 }
786 return;
787 }
788 if (phi != NULL) {
789 // Nothing in the loop before the store (next iteration)
790 // must observe the stored value
791 bool mem_ok = true;
792 {
793 ResourceMark rm;
794 Unique_Node_List wq;
795 wq.push(phi);
796 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
797 Node *m = wq.at(next);
798 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
799 Node* u = m->fast_out(i);
800 if (u->is_Store() || u->is_Phi()) {
801 if (u != n) {
802 wq.push(u);
803 mem_ok = (wq.size() <= 10);
804 }
805 } else {
806 mem_ok = false;
807 break;
808 }
809 }
810 }
811 }
812 if (mem_ok) {
813 // Move the Store out of the loop creating clones along
814 // all paths out of the loop that observe the stored value
815 _igvn.rehash_node_delayed(phi);
816 int count = phi->replace_edge(n, n->in(MemNode::Memory));
817 assert(count > 0, "inconsistent phi");
818 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
819 Node* u = n->fast_out(i);
820 Node* c = get_ctrl(u);
821
822 if (u->is_Phi()) {
823 c = u->in(0)->in(u->find_edge(n));
824 }
825 IdealLoopTree *u_loop = get_loop(c);
826 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
827 while(true) {
828 Node* next_c = find_non_split_ctrl(idom(c));
829 if (n_loop->is_member(get_loop(next_c))) {
830 break;
831 }
832 c = next_c;
833 }
834
835 Node* st = n->clone();
836 st->set_req(0, c);
837 _igvn.register_new_node_with_optimizer(st);
838
839 set_ctrl(st, c);
840 IdealLoopTree* new_loop = get_loop(c);
841 assert(new_loop != n_loop, "should be moved out of loop");
842 if (new_loop->_child == NULL) new_loop->_body.push(st);
843
844 _igvn.replace_input_of(u, u->find_edge(n), st);
845 --imax;
846 --i;
847 }
848
849
850 assert(n->outcnt() == 0, "all uses should be gone");
851 _igvn.replace_input_of(n, MemNode::Memory, C->top());
852 // Disconnect the phi now. An empty phi can confuse other
853 // optimizations in this pass of loop opts..
854 if (phi->in(LoopNode::LoopBackControl) == phi) {
855 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
856 n_loop->_body.yank(phi);
857 }
858 }
859 }
860 }
861 }
862 }
863 }
864
865 //------------------------------split_if_with_blocks_pre-----------------------
866 // Do the real work in a non-recursive function. Data nodes want to be
867 // cloned in the pre-order so they can feed each other nicely.
868 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
869 // Cloning these guys is unlikely to win
870 int n_op = n->Opcode();
871 if( n_op == Op_MergeMem ) return n;
872 if( n->is_Proj() ) return n;
873 // Do not clone-up CmpFXXX variations, as these are always
874 // followed by a CmpI
875 if( n->is_Cmp() ) return n;
876 // Attempt to use a conditional move instead of a phi/branch
877 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
878 Node *cmov = conditional_move( n );
879 if( cmov ) return cmov;
880 }
881 if( n->is_CFG() || n->is_LoadStore() )
882 return n;
883 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
884 n_op == Op_Opaque2 ) {
885 if( !C->major_progress() ) // If chance of no more loop opts...
886 _igvn._worklist.push(n); // maybe we'll remove them
887 return n;
888 }
889
890 if( n->is_Con() ) return n; // No cloning for Con nodes
891
892 Node *n_ctrl = get_ctrl(n);
893 if( !n_ctrl ) return n; // Dead node
894
895 Node* res = try_move_store_before_loop(n, n_ctrl);
896 if (res != NULL) {
897 return n;
898 }
899
900 // Attempt to remix address expressions for loop invariants
901 Node *m = remix_address_expressions( n );
902 if( m ) return m;
903
904 // Determine if the Node has inputs from some local Phi.
905 // Returns the block to clone thru.
906 Node *n_blk = has_local_phi_input( n );
907 if( !n_blk ) return n;
908
909 // Do not clone the trip counter through on a CountedLoop
910 // (messes up the canonical shape).
911 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
912
913 // Check for having no control input; not pinned. Allow
914 // dominating control.
915 if (n->in(0)) {
916 Node *dom = idom(n_blk);
917 if (dom_lca(n->in(0), dom) != n->in(0)) {
918 return n;
919 }
920 }
921 // Policy: when is it profitable. You must get more wins than
922 // policy before it is considered profitable. Policy is usually 0,
923 // so 1 win is considered profitable. Big merges will require big
924 // cloning, so get a larger policy.
925 int policy = n_blk->req() >> 2;
926
927 // If the loop is a candidate for range check elimination,
928 // delay splitting through it's phi until a later loop optimization
929 if (n_blk->is_CountedLoop()) {
930 IdealLoopTree *lp = get_loop(n_blk);
931 if (lp && lp->_rce_candidate) {
932 return n;
933 }
934 }
935
936 // Use same limit as split_if_with_blocks_post
937 if( C->live_nodes() > 35000 ) return n; // Method too big
938
939 // Split 'n' through the merge point if it is profitable
940 Node *phi = split_thru_phi( n, n_blk, policy );
941 if (!phi) return n;
942
943 // Found a Phi to split thru!
944 // Replace 'n' with the new phi
945 _igvn.replace_node( n, phi );
946 // Moved a load around the loop, 'en-registering' something.
947 if (n_blk->is_Loop() && n->is_Load() &&
948 !phi->in(LoopNode::LoopBackControl)->is_Load())
949 C->set_major_progress();
950
951 return phi;
952 }
953
954 static bool merge_point_too_heavy(Compile* C, Node* region) {
955 // Bail out if the region and its phis have too many users.
956 int weight = 0;
957 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
958 weight += region->fast_out(i)->outcnt();
959 }
960 int nodes_left = C->max_node_limit() - C->live_nodes();
961 if (weight * 8 > nodes_left) {
962 #ifndef PRODUCT
963 if (PrintOpto)
964 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
965 #endif
966 return true;
967 } else {
968 return false;
969 }
970 }
971
972 static bool merge_point_safe(Node* region) {
973 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
974 // having a PhiNode input. This sidesteps the dangerous case where the split
975 // ConvI2LNode may become TOP if the input Value() does not
976 // overlap the ConvI2L range, leaving a node which may not dominate its
977 // uses.
978 // A better fix for this problem can be found in the BugTraq entry, but
979 // expediency for Mantis demands this hack.
980 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
981 // split_if_with_blocks from splitting a block because we could not move around
982 // the FastLockNode.
983 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
984 Node* n = region->fast_out(i);
985 if (n->is_Phi()) {
986 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
987 Node* m = n->fast_out(j);
988 if (m->is_FastLock())
989 return false;
990 #ifdef _LP64
991 if (m->Opcode() == Op_ConvI2L)
992 return false;
993 #endif
994 }
995 }
996 }
997 return true;
998 }
999
1000
1001 //------------------------------place_near_use---------------------------------
1002 // Place some computation next to use but not inside inner loops.
1003 // For inner loop uses move it to the preheader area.
1004 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1005 IdealLoopTree *u_loop = get_loop( useblock );
1006 return (u_loop->_irreducible || u_loop->_child)
1007 ? useblock
1008 : u_loop->_head->in(LoopNode::EntryControl);
1009 }
1010
1011
1012 //------------------------------split_if_with_blocks_post----------------------
1013 // Do the real work in a non-recursive function. CFG hackery wants to be
1014 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1015 // info.
1016 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1017
1018 // Cloning Cmp through Phi's involves the split-if transform.
1019 // FastLock is not used by an If
1020 if( n->is_Cmp() && !n->is_FastLock() ) {
1021 if( C->live_nodes() > 35000 ) return; // Method too big
1022
1023 // Do not do 'split-if' if irreducible loops are present.
1024 if( _has_irreducible_loops )
1025 return;
1026
1027 Node *n_ctrl = get_ctrl(n);
1028 // Determine if the Node has inputs from some local Phi.
1029 // Returns the block to clone thru.
1030 Node *n_blk = has_local_phi_input( n );
1031 if( n_blk != n_ctrl ) return;
1032
1033 if( merge_point_too_heavy(C, n_ctrl) )
1034 return;
1035
1036 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1037 Node *bol = n->unique_out();
1038 assert( bol->is_Bool(), "expect a bool here" );
1039 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1040 Node *iff = bol->unique_out();
1041
1042 // Check some safety conditions
1043 if( iff->is_If() ) { // Classic split-if?
1044 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1045 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1046 // Can't split CMove with different control edge.
1047 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1048 if( get_ctrl(iff->in(2)) == n_ctrl ||
1049 get_ctrl(iff->in(3)) == n_ctrl )
1050 return; // Inputs not yet split-up
1051 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1052 return; // Loop-invar test gates loop-varying CMOVE
1053 }
1054 } else {
1055 return; // some other kind of node, such as an Allocate
1056 }
1057
1058 // Do not do 'split-if' if some paths are dead. First do dead code
1059 // elimination and then see if its still profitable.
1060 for( uint i = 1; i < n_ctrl->req(); i++ )
1061 if( n_ctrl->in(i) == C->top() )
1062 return;
1063
1064 // When is split-if profitable? Every 'win' on means some control flow
1065 // goes dead, so it's almost always a win.
1066 int policy = 0;
1067 // If trying to do a 'Split-If' at the loop head, it is only
1068 // profitable if the cmp folds up on BOTH paths. Otherwise we
1069 // risk peeling a loop forever.
1070
1071 // CNC - Disabled for now. Requires careful handling of loop
1072 // body selection for the cloned code. Also, make sure we check
1073 // for any input path not being in the same loop as n_ctrl. For
1074 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1075 // because the alternative loop entry points won't be converted
1076 // into LoopNodes.
1077 IdealLoopTree *n_loop = get_loop(n_ctrl);
1078 for( uint j = 1; j < n_ctrl->req(); j++ )
1079 if( get_loop(n_ctrl->in(j)) != n_loop )
1080 return;
1081
1082 // Check for safety of the merge point.
1083 if( !merge_point_safe(n_ctrl) ) {
1084 return;
1085 }
1086
1087 // Split compare 'n' through the merge point if it is profitable
1088 Node *phi = split_thru_phi( n, n_ctrl, policy );
1089 if( !phi ) return;
1090
1091 // Found a Phi to split thru!
1092 // Replace 'n' with the new phi
1093 _igvn.replace_node( n, phi );
1094
1095 // Now split the bool up thru the phi
1096 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1097 guarantee(bolphi != NULL, "null boolean phi node");
1098
1099 _igvn.replace_node( bol, bolphi );
1100 assert( iff->in(1) == bolphi, "" );
1101
1102 if( bolphi->Value(&_igvn)->singleton() )
1103 return;
1104
1105 // Conditional-move? Must split up now
1106 if( !iff->is_If() ) {
1107 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1108 _igvn.replace_node( iff, cmovphi );
1109 return;
1110 }
1111
1112 // Now split the IF
1113 do_split_if( iff );
1114 return;
1115 }
1116
1117 // Check for an IF ready to split; one that has its
1118 // condition codes input coming from a Phi at the block start.
1119 int n_op = n->Opcode();
1120
1121 // Check for an IF being dominated by another IF same test
1122 if (n_op == Op_If) {
1123 Node *bol = n->in(1);
1124 uint max = bol->outcnt();
1125 // Check for same test used more than once?
1126 if (max > 1 && bol->is_Bool()) {
1127 // Search up IDOMs to see if this IF is dominated.
1128 Node *cutoff = get_ctrl(bol);
1129
1130 // Now search up IDOMs till cutoff, looking for a dominating test
1131 Node *prevdom = n;
1132 Node *dom = idom(prevdom);
1133 while (dom != cutoff) {
1134 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1135 // Replace the dominated test with an obvious true or false.
1136 // Place it on the IGVN worklist for later cleanup.
1137 C->set_major_progress();
1138 dominated_by(prevdom, n, false, true);
1139 #ifndef PRODUCT
1140 if( VerifyLoopOptimizations ) verify();
1141 #endif
1142 return;
1143 }
1144 prevdom = dom;
1145 dom = idom(prevdom);
1146 }
1147 }
1148 }
1149
1150 // See if a shared loop-varying computation has no loop-varying uses.
1151 // Happens if something is only used for JVM state in uncommon trap exits,
1152 // like various versions of induction variable+offset. Clone the
1153 // computation per usage to allow it to sink out of the loop.
1154 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1155 Node *n_ctrl = get_ctrl(n);
1156 IdealLoopTree *n_loop = get_loop(n_ctrl);
1157 if( n_loop != _ltree_root ) {
1158 DUIterator_Fast imax, i = n->fast_outs(imax);
1159 for (; i < imax; i++) {
1160 Node* u = n->fast_out(i);
1161 if( !has_ctrl(u) ) break; // Found control user
1162 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1163 if( u_loop == n_loop ) break; // Found loop-varying use
1164 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1165 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1166 }
1167 bool did_break = (i < imax); // Did we break out of the previous loop?
1168 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1169 Node *late_load_ctrl = NULL;
1170 if (n->is_Load()) {
1171 // If n is a load, get and save the result from get_late_ctrl(),
1172 // to be later used in calculating the control for n's clones.
1173 clear_dom_lca_tags();
1174 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1175 }
1176 // If n is a load, and the late control is the same as the current
1177 // control, then the cloning of n is a pointless exercise, because
1178 // GVN will ensure that we end up where we started.
1179 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1180 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1181 Node *u = n->last_out(j); // Clone private computation per use
1182 _igvn.rehash_node_delayed(u);
1183 Node *x = n->clone(); // Clone computation
1184 Node *x_ctrl = NULL;
1185 if( u->is_Phi() ) {
1186 // Replace all uses of normal nodes. Replace Phi uses
1187 // individually, so the separate Nodes can sink down
1188 // different paths.
1189 uint k = 1;
1190 while( u->in(k) != n ) k++;
1191 u->set_req( k, x );
1192 // x goes next to Phi input path
1193 x_ctrl = u->in(0)->in(k);
1194 --j;
1195 } else { // Normal use
1196 // Replace all uses
1197 for( uint k = 0; k < u->req(); k++ ) {
1198 if( u->in(k) == n ) {
1199 u->set_req( k, x );
1200 --j;
1201 }
1202 }
1203 x_ctrl = get_ctrl(u);
1204 }
1205
1206 // Find control for 'x' next to use but not inside inner loops.
1207 // For inner loop uses get the preheader area.
1208 x_ctrl = place_near_use(x_ctrl);
1209
1210 if (n->is_Load()) {
1211 // For loads, add a control edge to a CFG node outside of the loop
1212 // to force them to not combine and return back inside the loop
1213 // during GVN optimization (4641526).
1214 //
1215 // Because we are setting the actual control input, factor in
1216 // the result from get_late_ctrl() so we respect any
1217 // anti-dependences. (6233005).
1218 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1219
1220 // Don't allow the control input to be a CFG splitting node.
1221 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1222 // should only have IfTrueNode and IfFalseNode (4985384).
1223 x_ctrl = find_non_split_ctrl(x_ctrl);
1224 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1225
1226 x->set_req(0, x_ctrl);
1227 }
1228 register_new_node(x, x_ctrl);
1229
1230 // Some institutional knowledge is needed here: 'x' is
1231 // yanked because if the optimizer runs GVN on it all the
1232 // cloned x's will common up and undo this optimization and
1233 // be forced back in the loop. This is annoying because it
1234 // makes +VerifyOpto report false-positives on progress. I
1235 // tried setting control edges on the x's to force them to
1236 // not combine, but the matching gets worried when it tries
1237 // to fold a StoreP and an AddP together (as part of an
1238 // address expression) and the AddP and StoreP have
1239 // different controls.
1240 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1241 }
1242 _igvn.remove_dead_node(n);
1243 }
1244 }
1245 }
1246 }
1247
1248 try_move_store_after_loop(n);
1249
1250 // Check for Opaque2's who's loop has disappeared - who's input is in the
1251 // same loop nest as their output. Remove 'em, they are no longer useful.
1252 if( n_op == Op_Opaque2 &&
1253 n->in(1) != NULL &&
1254 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1255 _igvn.replace_node( n, n->in(1) );
1256 }
1257 }
1258
1259 //------------------------------split_if_with_blocks---------------------------
1260 // Check for aggressive application of 'split-if' optimization,
1261 // using basic block level info.
1262 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1263 Node *n = C->root();
1264 visited.set(n->_idx); // first, mark node as visited
1265 // Do pre-visit work for root
1266 n = split_if_with_blocks_pre( n );
1267 uint cnt = n->outcnt();
1268 uint i = 0;
1269 while (true) {
1270 // Visit all children
1271 if (i < cnt) {
1272 Node* use = n->raw_out(i);
1273 ++i;
1274 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1275 // Now do pre-visit work for this use
1276 use = split_if_with_blocks_pre( use );
1277 nstack.push(n, i); // Save parent and next use's index.
1278 n = use; // Process all children of current use.
1279 cnt = use->outcnt();
1280 i = 0;
1281 }
1282 }
1283 else {
1284 // All of n's children have been processed, complete post-processing.
1285 if (cnt != 0 && !n->is_Con()) {
1286 assert(has_node(n), "no dead nodes");
1287 split_if_with_blocks_post( n );
1288 }
1289 if (nstack.is_empty()) {
1290 // Finished all nodes on stack.
1291 break;
1292 }
1293 // Get saved parent node and next use's index. Visit the rest of uses.
1294 n = nstack.node();
1295 cnt = n->outcnt();
1296 i = nstack.index();
1297 nstack.pop();
1298 }
1299 }
1300 }
1301
1302
1303 //=============================================================================
1304 //
1305 // C L O N E A L O O P B O D Y
1306 //
1307
1308 //------------------------------clone_iff--------------------------------------
1309 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1310 // "Nearly" because all Nodes have been cloned from the original in the loop,
1311 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1312 // through the Phi recursively, and return a Bool.
1313 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1314
1315 // Convert this Phi into a Phi merging Bools
1316 uint i;
1317 for( i = 1; i < phi->req(); i++ ) {
1318 Node *b = phi->in(i);
1319 if( b->is_Phi() ) {
1320 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1321 } else {
1322 assert( b->is_Bool(), "" );
1323 }
1324 }
1325
1326 Node *sample_bool = phi->in(1);
1327 Node *sample_cmp = sample_bool->in(1);
1328
1329 // Make Phis to merge the Cmp's inputs.
1330 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1331 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1332 for( i = 1; i < phi->req(); i++ ) {
1333 Node *n1 = phi->in(i)->in(1)->in(1);
1334 Node *n2 = phi->in(i)->in(1)->in(2);
1335 phi1->set_req( i, n1 );
1336 phi2->set_req( i, n2 );
1337 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1338 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1339 }
1340 // See if these Phis have been made before.
1341 // Register with optimizer
1342 Node *hit1 = _igvn.hash_find_insert(phi1);
1343 if( hit1 ) { // Hit, toss just made Phi
1344 _igvn.remove_dead_node(phi1); // Remove new phi
1345 assert( hit1->is_Phi(), "" );
1346 phi1 = (PhiNode*)hit1; // Use existing phi
1347 } else { // Miss
1348 _igvn.register_new_node_with_optimizer(phi1);
1349 }
1350 Node *hit2 = _igvn.hash_find_insert(phi2);
1351 if( hit2 ) { // Hit, toss just made Phi
1352 _igvn.remove_dead_node(phi2); // Remove new phi
1353 assert( hit2->is_Phi(), "" );
1354 phi2 = (PhiNode*)hit2; // Use existing phi
1355 } else { // Miss
1356 _igvn.register_new_node_with_optimizer(phi2);
1357 }
1358 // Register Phis with loop/block info
1359 set_ctrl(phi1, phi->in(0));
1360 set_ctrl(phi2, phi->in(0));
1361 // Make a new Cmp
1362 Node *cmp = sample_cmp->clone();
1363 cmp->set_req( 1, phi1 );
1364 cmp->set_req( 2, phi2 );
1365 _igvn.register_new_node_with_optimizer(cmp);
1366 set_ctrl(cmp, phi->in(0));
1367
1368 // Make a new Bool
1369 Node *b = sample_bool->clone();
1370 b->set_req(1,cmp);
1371 _igvn.register_new_node_with_optimizer(b);
1372 set_ctrl(b, phi->in(0));
1373
1374 assert( b->is_Bool(), "" );
1375 return (BoolNode*)b;
1376 }
1377
1378 //------------------------------clone_bool-------------------------------------
1379 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1380 // "Nearly" because all Nodes have been cloned from the original in the loop,
1381 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1382 // through the Phi recursively, and return a Bool.
1383 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1384 uint i;
1385 // Convert this Phi into a Phi merging Bools
1386 for( i = 1; i < phi->req(); i++ ) {
1387 Node *b = phi->in(i);
1388 if( b->is_Phi() ) {
1389 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1390 } else {
1391 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1392 }
1393 }
1394
1395 Node *sample_cmp = phi->in(1);
1396
1397 // Make Phis to merge the Cmp's inputs.
1398 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1399 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1400 for( uint j = 1; j < phi->req(); j++ ) {
1401 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1402 Node *n1, *n2;
1403 if( cmp_top->is_Cmp() ) {
1404 n1 = cmp_top->in(1);
1405 n2 = cmp_top->in(2);
1406 } else {
1407 n1 = n2 = cmp_top;
1408 }
1409 phi1->set_req( j, n1 );
1410 phi2->set_req( j, n2 );
1411 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1412 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1413 }
1414
1415 // See if these Phis have been made before.
1416 // Register with optimizer
1417 Node *hit1 = _igvn.hash_find_insert(phi1);
1418 if( hit1 ) { // Hit, toss just made Phi
1419 _igvn.remove_dead_node(phi1); // Remove new phi
1420 assert( hit1->is_Phi(), "" );
1421 phi1 = (PhiNode*)hit1; // Use existing phi
1422 } else { // Miss
1423 _igvn.register_new_node_with_optimizer(phi1);
1424 }
1425 Node *hit2 = _igvn.hash_find_insert(phi2);
1426 if( hit2 ) { // Hit, toss just made Phi
1427 _igvn.remove_dead_node(phi2); // Remove new phi
1428 assert( hit2->is_Phi(), "" );
1429 phi2 = (PhiNode*)hit2; // Use existing phi
1430 } else { // Miss
1431 _igvn.register_new_node_with_optimizer(phi2);
1432 }
1433 // Register Phis with loop/block info
1434 set_ctrl(phi1, phi->in(0));
1435 set_ctrl(phi2, phi->in(0));
1436 // Make a new Cmp
1437 Node *cmp = sample_cmp->clone();
1438 cmp->set_req( 1, phi1 );
1439 cmp->set_req( 2, phi2 );
1440 _igvn.register_new_node_with_optimizer(cmp);
1441 set_ctrl(cmp, phi->in(0));
1442
1443 assert( cmp->is_Cmp(), "" );
1444 return (CmpNode*)cmp;
1445 }
1446
1447 //------------------------------sink_use---------------------------------------
1448 // If 'use' was in the loop-exit block, it now needs to be sunk
1449 // below the post-loop merge point.
1450 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1451 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1452 set_ctrl(use, post_loop);
1453 for (DUIterator j = use->outs(); use->has_out(j); j++)
1454 sink_use(use->out(j), post_loop);
1455 }
1456 }
1457
1458 //------------------------------clone_loop-------------------------------------
1459 //
1460 // C L O N E A L O O P B O D Y
1461 //
1462 // This is the basic building block of the loop optimizations. It clones an
1463 // entire loop body. It makes an old_new loop body mapping; with this mapping
1464 // you can find the new-loop equivalent to an old-loop node. All new-loop
1465 // nodes are exactly equal to their old-loop counterparts, all edges are the
1466 // same. All exits from the old-loop now have a RegionNode that merges the
1467 // equivalent new-loop path. This is true even for the normal "loop-exit"
1468 // condition. All uses of loop-invariant old-loop values now come from (one
1469 // or more) Phis that merge their new-loop equivalents.
1470 //
1471 // This operation leaves the graph in an illegal state: there are two valid
1472 // control edges coming from the loop pre-header to both loop bodies. I'll
1473 // definitely have to hack the graph after running this transform.
1474 //
1475 // From this building block I will further edit edges to perform loop peeling
1476 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1477 //
1478 // Parameter side_by_size_idom:
1479 // When side_by_size_idom is NULL, the dominator tree is constructed for
1480 // the clone loop to dominate the original. Used in construction of
1481 // pre-main-post loop sequence.
1482 // When nonnull, the clone and original are side-by-side, both are
1483 // dominated by the side_by_side_idom node. Used in construction of
1484 // unswitched loops.
1485 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1486 Node* side_by_side_idom) {
1487
1488 #ifndef PRODUCT
1489 if (C->do_vector_loop() && PrintOpto) {
1490 const char* mname = C->method()->name()->as_quoted_ascii();
1491 if (mname != NULL) {
1492 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1493 }
1494 }
1495 #endif
1496
1497 CloneMap& cm = C->clone_map();
1498 Dict* dict = cm.dict();
1499 if (C->do_vector_loop()) {
1500 cm.set_clone_idx(cm.max_gen()+1);
1501 #ifndef PRODUCT
1502 if (PrintOpto) {
1503 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1504 loop->dump_head();
1505 }
1506 #endif
1507 }
1508
1509 // Step 1: Clone the loop body. Make the old->new mapping.
1510 uint i;
1511 for( i = 0; i < loop->_body.size(); i++ ) {
1512 Node *old = loop->_body.at(i);
1513 Node *nnn = old->clone();
1514 old_new.map( old->_idx, nnn );
1515 if (C->do_vector_loop()) {
1516 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1517 }
1518 _igvn.register_new_node_with_optimizer(nnn);
1519 }
1520
1521
1522 // Step 2: Fix the edges in the new body. If the old input is outside the
1523 // loop use it. If the old input is INside the loop, use the corresponding
1524 // new node instead.
1525 for( i = 0; i < loop->_body.size(); i++ ) {
1526 Node *old = loop->_body.at(i);
1527 Node *nnn = old_new[old->_idx];
1528 // Fix CFG/Loop controlling the new node
1529 if (has_ctrl(old)) {
1530 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1531 } else {
1532 set_loop(nnn, loop->_parent);
1533 if (old->outcnt() > 0) {
1534 set_idom( nnn, old_new[idom(old)->_idx], dd );
1535 }
1536 }
1537 // Correct edges to the new node
1538 for( uint j = 0; j < nnn->req(); j++ ) {
1539 Node *n = nnn->in(j);
1540 if( n ) {
1541 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1542 if( loop->is_member( old_in_loop ) )
1543 nnn->set_req(j, old_new[n->_idx]);
1544 }
1545 }
1546 _igvn.hash_find_insert(nnn);
1547 }
1548 Node *newhead = old_new[loop->_head->_idx];
1549 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1550
1551
1552 // Step 3: Now fix control uses. Loop varying control uses have already
1553 // been fixed up (as part of all input edges in Step 2). Loop invariant
1554 // control uses must be either an IfFalse or an IfTrue. Make a merge
1555 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1556 // refer to this.
1557 ResourceArea *area = Thread::current()->resource_area();
1558 Node_List worklist(area);
1559 uint new_counter = C->unique();
1560 for( i = 0; i < loop->_body.size(); i++ ) {
1561 Node* old = loop->_body.at(i);
1562 if( !old->is_CFG() ) continue;
1563 Node* nnn = old_new[old->_idx];
1564
1565 // Copy uses to a worklist, so I can munge the def-use info
1566 // with impunity.
1567 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1568 worklist.push(old->fast_out(j));
1569
1570 while( worklist.size() ) { // Visit all uses
1571 Node *use = worklist.pop();
1572 if (!has_node(use)) continue; // Ignore dead nodes
1573 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1574 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1575 // Both OLD and USE are CFG nodes here.
1576 assert( use->is_Proj(), "" );
1577
1578 // Clone the loop exit control projection
1579 Node *newuse = use->clone();
1580 if (C->do_vector_loop()) {
1581 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1582 }
1583 newuse->set_req(0,nnn);
1584 _igvn.register_new_node_with_optimizer(newuse);
1585 set_loop(newuse, use_loop);
1586 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1587
1588 // We need a Region to merge the exit from the peeled body and the
1589 // exit from the old loop body.
1590 RegionNode *r = new RegionNode(3);
1591 // Map the old use to the new merge point
1592 old_new.map( use->_idx, r );
1593 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1594 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1595
1596 // The original user of 'use' uses 'r' instead.
1597 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1598 Node* useuse = use->last_out(l);
1599 _igvn.rehash_node_delayed(useuse);
1600 uint uses_found = 0;
1601 if( useuse->in(0) == use ) {
1602 useuse->set_req(0, r);
1603 uses_found++;
1604 if( useuse->is_CFG() ) {
1605 assert( dom_depth(useuse) > dd_r, "" );
1606 set_idom(useuse, r, dom_depth(useuse));
1607 }
1608 }
1609 for( uint k = 1; k < useuse->req(); k++ ) {
1610 if( useuse->in(k) == use ) {
1611 useuse->set_req(k, r);
1612 uses_found++;
1613 }
1614 }
1615 l -= uses_found; // we deleted 1 or more copies of this edge
1616 }
1617
1618 // Now finish up 'r'
1619 r->set_req( 1, newuse );
1620 r->set_req( 2, use );
1621 _igvn.register_new_node_with_optimizer(r);
1622 set_loop(r, use_loop);
1623 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1624 } // End of if a loop-exit test
1625 }
1626 }
1627
1628 // Step 4: If loop-invariant use is not control, it must be dominated by a
1629 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1630 // there if needed. Make a Phi there merging old and new used values.
1631 Node_List *split_if_set = NULL;
1632 Node_List *split_bool_set = NULL;
1633 Node_List *split_cex_set = NULL;
1634 for( i = 0; i < loop->_body.size(); i++ ) {
1635 Node* old = loop->_body.at(i);
1636 Node* nnn = old_new[old->_idx];
1637 // Copy uses to a worklist, so I can munge the def-use info
1638 // with impunity.
1639 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1640 worklist.push(old->fast_out(j));
1641
1642 while( worklist.size() ) {
1643 Node *use = worklist.pop();
1644 if (!has_node(use)) continue; // Ignore dead nodes
1645 if (use->in(0) == C->top()) continue;
1646 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1647 // Check for data-use outside of loop - at least one of OLD or USE
1648 // must not be a CFG node.
1649 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1650
1651 // If the Data use is an IF, that means we have an IF outside of the
1652 // loop that is switching on a condition that is set inside of the
1653 // loop. Happens if people set a loop-exit flag; then test the flag
1654 // in the loop to break the loop, then test is again outside of the
1655 // loop to determine which way the loop exited.
1656 // Loop predicate If node connects to Bool node through Opaque1 node.
1657 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1658 // Since this code is highly unlikely, we lazily build the worklist
1659 // of such Nodes to go split.
1660 if( !split_if_set )
1661 split_if_set = new Node_List(area);
1662 split_if_set->push(use);
1663 }
1664 if( use->is_Bool() ) {
1665 if( !split_bool_set )
1666 split_bool_set = new Node_List(area);
1667 split_bool_set->push(use);
1668 }
1669 if( use->Opcode() == Op_CreateEx ) {
1670 if( !split_cex_set )
1671 split_cex_set = new Node_List(area);
1672 split_cex_set->push(use);
1673 }
1674
1675
1676 // Get "block" use is in
1677 uint idx = 0;
1678 while( use->in(idx) != old ) idx++;
1679 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1680 assert( !loop->is_member( get_loop( prev ) ), "" );
1681 Node *cfg = prev->_idx >= new_counter
1682 ? prev->in(2)
1683 : idom(prev);
1684 if( use->is_Phi() ) // Phi use is in prior block
1685 cfg = prev->in(idx); // NOT in block of Phi itself
1686 if (cfg->is_top()) { // Use is dead?
1687 _igvn.replace_input_of(use, idx, C->top());
1688 continue;
1689 }
1690
1691 while( !loop->is_member( get_loop( cfg ) ) ) {
1692 prev = cfg;
1693 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1694 }
1695 // If the use occurs after merging several exits from the loop, then
1696 // old value must have dominated all those exits. Since the same old
1697 // value was used on all those exits we did not need a Phi at this
1698 // merge point. NOW we do need a Phi here. Each loop exit value
1699 // is now merged with the peeled body exit; each exit gets its own
1700 // private Phi and those Phis need to be merged here.
1701 Node *phi;
1702 if( prev->is_Region() ) {
1703 if( idx == 0 ) { // Updating control edge?
1704 phi = prev; // Just use existing control
1705 } else { // Else need a new Phi
1706 phi = PhiNode::make( prev, old );
1707 // Now recursively fix up the new uses of old!
1708 for( uint i = 1; i < prev->req(); i++ ) {
1709 worklist.push(phi); // Onto worklist once for each 'old' input
1710 }
1711 }
1712 } else {
1713 // Get new RegionNode merging old and new loop exits
1714 prev = old_new[prev->_idx];
1715 assert( prev, "just made this in step 7" );
1716 if( idx == 0 ) { // Updating control edge?
1717 phi = prev; // Just use existing control
1718 } else { // Else need a new Phi
1719 // Make a new Phi merging data values properly
1720 phi = PhiNode::make( prev, old );
1721 phi->set_req( 1, nnn );
1722 }
1723 }
1724 // If inserting a new Phi, check for prior hits
1725 if( idx != 0 ) {
1726 Node *hit = _igvn.hash_find_insert(phi);
1727 if( hit == NULL ) {
1728 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1729 } else { // or
1730 // Remove the new phi from the graph and use the hit
1731 _igvn.remove_dead_node(phi);
1732 phi = hit; // Use existing phi
1733 }
1734 set_ctrl(phi, prev);
1735 }
1736 // Make 'use' use the Phi instead of the old loop body exit value
1737 _igvn.replace_input_of(use, idx, phi);
1738 if( use->_idx >= new_counter ) { // If updating new phis
1739 // Not needed for correctness, but prevents a weak assert
1740 // in AddPNode from tripping (when we end up with different
1741 // base & derived Phis that will become the same after
1742 // IGVN does CSE).
1743 Node *hit = _igvn.hash_find_insert(use);
1744 if( hit ) // Go ahead and re-hash for hits.
1745 _igvn.replace_node( use, hit );
1746 }
1747
1748 // If 'use' was in the loop-exit block, it now needs to be sunk
1749 // below the post-loop merge point.
1750 sink_use( use, prev );
1751 }
1752 }
1753 }
1754
1755 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1756 // the loop uses a condition set in the loop. The original IF probably
1757 // takes control from one or more OLD Regions (which in turn get from NEW
1758 // Regions). In any case, there will be a set of Phis for each merge point
1759 // from the IF up to where the original BOOL def exists the loop.
1760 if( split_if_set ) {
1761 while( split_if_set->size() ) {
1762 Node *iff = split_if_set->pop();
1763 if( iff->in(1)->is_Phi() ) {
1764 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1765 _igvn.replace_input_of(iff, 1, b);
1766 }
1767 }
1768 }
1769 if( split_bool_set ) {
1770 while( split_bool_set->size() ) {
1771 Node *b = split_bool_set->pop();
1772 Node *phi = b->in(1);
1773 assert( phi->is_Phi(), "" );
1774 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1775 _igvn.replace_input_of(b, 1, cmp);
1776 }
1777 }
1778 if( split_cex_set ) {
1779 while( split_cex_set->size() ) {
1780 Node *b = split_cex_set->pop();
1781 assert( b->in(0)->is_Region(), "" );
1782 assert( b->in(1)->is_Phi(), "" );
1783 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1784 split_up( b, b->in(0), NULL );
1785 }
1786 }
1787
1788 }
1789
1790
1791 //---------------------- stride_of_possible_iv -------------------------------------
1792 // Looks for an iff/bool/comp with one operand of the compare
1793 // being a cycle involving an add and a phi,
1794 // with an optional truncation (left-shift followed by a right-shift)
1795 // of the add. Returns zero if not an iv.
1796 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1797 Node* trunc1 = NULL;
1798 Node* trunc2 = NULL;
1799 const TypeInt* ttype = NULL;
1800 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1801 return 0;
1802 }
1803 BoolNode* bl = iff->in(1)->as_Bool();
1804 Node* cmp = bl->in(1);
1805 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1806 return 0;
1807 }
1808 // Must have an invariant operand
1809 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1810 return 0;
1811 }
1812 Node* add2 = NULL;
1813 Node* cmp1 = cmp->in(1);
1814 if (cmp1->is_Phi()) {
1815 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1816 Node* phi = cmp1;
1817 for (uint i = 1; i < phi->req(); i++) {
1818 Node* in = phi->in(i);
1819 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1820 &trunc1, &trunc2, &ttype);
1821 if (add && add->in(1) == phi) {
1822 add2 = add->in(2);
1823 break;
1824 }
1825 }
1826 } else {
1827 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1828 Node* addtrunc = cmp1;
1829 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1830 &trunc1, &trunc2, &ttype);
1831 if (add && add->in(1)->is_Phi()) {
1832 Node* phi = add->in(1);
1833 for (uint i = 1; i < phi->req(); i++) {
1834 if (phi->in(i) == addtrunc) {
1835 add2 = add->in(2);
1836 break;
1837 }
1838 }
1839 }
1840 }
1841 if (add2 != NULL) {
1842 const TypeInt* add2t = _igvn.type(add2)->is_int();
1843 if (add2t->is_con()) {
1844 return add2t->get_con();
1845 }
1846 }
1847 return 0;
1848 }
1849
1850
1851 //---------------------- stay_in_loop -------------------------------------
1852 // Return the (unique) control output node that's in the loop (if it exists.)
1853 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1854 Node* unique = NULL;
1855 if (!n) return NULL;
1856 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1857 Node* use = n->fast_out(i);
1858 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1859 if (unique != NULL) {
1860 return NULL;
1861 }
1862 unique = use;
1863 }
1864 }
1865 return unique;
1866 }
1867
1868 //------------------------------ register_node -------------------------------------
1869 // Utility to register node "n" with PhaseIdealLoop
1870 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1871 _igvn.register_new_node_with_optimizer(n);
1872 loop->_body.push(n);
1873 if (n->is_CFG()) {
1874 set_loop(n, loop);
1875 set_idom(n, pred, ddepth);
1876 } else {
1877 set_ctrl(n, pred);
1878 }
1879 }
1880
1881 //------------------------------ proj_clone -------------------------------------
1882 // Utility to create an if-projection
1883 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1884 ProjNode* c = p->clone()->as_Proj();
1885 c->set_req(0, iff);
1886 return c;
1887 }
1888
1889 //------------------------------ short_circuit_if -------------------------------------
1890 // Force the iff control output to be the live_proj
1891 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1892 guarantee(live_proj != NULL, "null projection");
1893 int proj_con = live_proj->_con;
1894 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1895 Node *con = _igvn.intcon(proj_con);
1896 set_ctrl(con, C->root());
1897 if (iff) {
1898 iff->set_req(1, con);
1899 }
1900 return con;
1901 }
1902
1903 //------------------------------ insert_if_before_proj -------------------------------------
1904 // Insert a new if before an if projection (* - new node)
1905 //
1906 // before
1907 // if(test)
1908 // / \
1909 // v v
1910 // other-proj proj (arg)
1911 //
1912 // after
1913 // if(test)
1914 // / \
1915 // / v
1916 // | * proj-clone
1917 // v |
1918 // other-proj v
1919 // * new_if(relop(cmp[IU](left,right)))
1920 // / \
1921 // v v
1922 // * new-proj proj
1923 // (returned)
1924 //
1925 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1926 IfNode* iff = proj->in(0)->as_If();
1927 IdealLoopTree *loop = get_loop(proj);
1928 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1929 int ddepth = dom_depth(proj);
1930
1931 _igvn.rehash_node_delayed(iff);
1932 _igvn.rehash_node_delayed(proj);
1933
1934 proj->set_req(0, NULL); // temporary disconnect
1935 ProjNode* proj2 = proj_clone(proj, iff);
1936 register_node(proj2, loop, iff, ddepth);
1937
1938 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1939 register_node(cmp, loop, proj2, ddepth);
1940
1941 BoolNode* bol = new BoolNode(cmp, relop);
1942 register_node(bol, loop, proj2, ddepth);
1943
1944 IfNode* new_if = new IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1945 register_node(new_if, loop, proj2, ddepth);
1946
1947 proj->set_req(0, new_if); // reattach
1948 set_idom(proj, new_if, ddepth);
1949
1950 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1951 guarantee(new_exit != NULL, "null exit node");
1952 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1953
1954 return new_exit;
1955 }
1956
1957 //------------------------------ insert_region_before_proj -------------------------------------
1958 // Insert a region before an if projection (* - new node)
1959 //
1960 // before
1961 // if(test)
1962 // / |
1963 // v |
1964 // proj v
1965 // other-proj
1966 //
1967 // after
1968 // if(test)
1969 // / |
1970 // v |
1971 // * proj-clone v
1972 // | other-proj
1973 // v
1974 // * new-region
1975 // |
1976 // v
1977 // * dum_if
1978 // / \
1979 // v \
1980 // * dum-proj v
1981 // proj
1982 //
1983 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1984 IfNode* iff = proj->in(0)->as_If();
1985 IdealLoopTree *loop = get_loop(proj);
1986 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1987 int ddepth = dom_depth(proj);
1988
1989 _igvn.rehash_node_delayed(iff);
1990 _igvn.rehash_node_delayed(proj);
1991
1992 proj->set_req(0, NULL); // temporary disconnect
1993 ProjNode* proj2 = proj_clone(proj, iff);
1994 register_node(proj2, loop, iff, ddepth);
1995
1996 RegionNode* reg = new RegionNode(2);
1997 reg->set_req(1, proj2);
1998 register_node(reg, loop, iff, ddepth);
1999
2000 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2001 register_node(dum_if, loop, reg, ddepth);
2002
2003 proj->set_req(0, dum_if); // reattach
2004 set_idom(proj, dum_if, ddepth);
2005
2006 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2007 register_node(dum_proj, loop, dum_if, ddepth);
2008
2009 return reg;
2010 }
2011
2012 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2013 // Clone a signed compare loop exit from an unsigned compare and
2014 // insert it before the unsigned cmp on the stay-in-loop path.
2015 // All new nodes inserted in the dominator tree between the original
2016 // if and it's projections. The original if test is replaced with
2017 // a constant to force the stay-in-loop path.
2018 //
2019 // This is done to make sure that the original if and it's projections
2020 // still dominate the same set of control nodes, that the ctrl() relation
2021 // from data nodes to them is preserved, and that their loop nesting is
2022 // preserved.
2023 //
2024 // before
2025 // if(i <u limit) unsigned compare loop exit
2026 // / |
2027 // v v
2028 // exit-proj stay-in-loop-proj
2029 //
2030 // after
2031 // if(stay-in-loop-const) original if
2032 // / |
2033 // / v
2034 // / if(i < limit) new signed test
2035 // / / |
2036 // / / v
2037 // / / if(i <u limit) new cloned unsigned test
2038 // / / / |
2039 // v v v |
2040 // region |
2041 // | |
2042 // dum-if |
2043 // / | |
2044 // ether | |
2045 // v v
2046 // exit-proj stay-in-loop-proj
2047 //
2048 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2049 const bool Signed = true;
2050 const bool Unsigned = false;
2051
2052 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2053 if (bol->_test._test != BoolTest::lt) return NULL;
2054 CmpNode* cmpu = bol->in(1)->as_Cmp();
2055 if (cmpu->Opcode() != Op_CmpU) return NULL;
2056 int stride = stride_of_possible_iv(if_cmpu);
2057 if (stride == 0) return NULL;
2058
2059 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2060 guarantee(lp_proj != NULL, "null loop node");
2061
2062 ProjNode* lp_continue = lp_proj->as_Proj();
2063 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2064
2065 Node* limit = NULL;
2066 if (stride > 0) {
2067 limit = cmpu->in(2);
2068 } else {
2069 limit = _igvn.makecon(TypeInt::ZERO);
2070 set_ctrl(limit, C->root());
2071 }
2072 // Create a new region on the exit path
2073 RegionNode* reg = insert_region_before_proj(lp_exit);
2074 guarantee(reg != NULL, "null region node");
2075
2076 // Clone the if-cmpu-true-false using a signed compare
2077 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2078 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2079 reg->add_req(cmpi_exit);
2080
2081 // Clone the if-cmpu-true-false
2082 BoolTest::mask rel_u = bol->_test._test;
2083 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2084 reg->add_req(cmpu_exit);
2085
2086 // Force original if to stay in loop.
2087 short_circuit_if(if_cmpu, lp_continue);
2088
2089 return cmpi_exit->in(0)->as_If();
2090 }
2091
2092 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2093 // Remove a previously inserted signed compare loop exit.
2094 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2095 Node* lp_proj = stay_in_loop(if_cmp, loop);
2096 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2097 stay_in_loop(lp_proj, loop)->is_If() &&
2098 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2099 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2100 set_ctrl(con, C->root());
2101 if_cmp->set_req(1, con);
2102 }
2103
2104 //------------------------------ scheduled_nodelist -------------------------------------
2105 // Create a post order schedule of nodes that are in the
2106 // "member" set. The list is returned in "sched".
2107 // The first node in "sched" is the loop head, followed by
2108 // nodes which have no inputs in the "member" set, and then
2109 // followed by the nodes that have an immediate input dependence
2110 // on a node in "sched".
2111 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2112
2113 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2114 Arena *a = Thread::current()->resource_area();
2115 VectorSet visited(a);
2116 Node_Stack nstack(a, loop->_body.size());
2117
2118 Node* n = loop->_head; // top of stack is cached in "n"
2119 uint idx = 0;
2120 visited.set(n->_idx);
2121
2122 // Initially push all with no inputs from within member set
2123 for(uint i = 0; i < loop->_body.size(); i++ ) {
2124 Node *elt = loop->_body.at(i);
2125 if (member.test(elt->_idx)) {
2126 bool found = false;
2127 for (uint j = 0; j < elt->req(); j++) {
2128 Node* def = elt->in(j);
2129 if (def && member.test(def->_idx) && def != elt) {
2130 found = true;
2131 break;
2132 }
2133 }
2134 if (!found && elt != loop->_head) {
2135 nstack.push(n, idx);
2136 n = elt;
2137 assert(!visited.test(n->_idx), "not seen yet");
2138 visited.set(n->_idx);
2139 }
2140 }
2141 }
2142
2143 // traverse out's that are in the member set
2144 while (true) {
2145 if (idx < n->outcnt()) {
2146 Node* use = n->raw_out(idx);
2147 idx++;
2148 if (!visited.test_set(use->_idx)) {
2149 if (member.test(use->_idx)) {
2150 nstack.push(n, idx);
2151 n = use;
2152 idx = 0;
2153 }
2154 }
2155 } else {
2156 // All outputs processed
2157 sched.push(n);
2158 if (nstack.is_empty()) break;
2159 n = nstack.node();
2160 idx = nstack.index();
2161 nstack.pop();
2162 }
2163 }
2164 }
2165
2166
2167 //------------------------------ has_use_in_set -------------------------------------
2168 // Has a use in the vector set
2169 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2170 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2171 Node* use = n->fast_out(j);
2172 if (vset.test(use->_idx)) {
2173 return true;
2174 }
2175 }
2176 return false;
2177 }
2178
2179
2180 //------------------------------ has_use_internal_to_set -------------------------------------
2181 // Has use internal to the vector set (ie. not in a phi at the loop head)
2182 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2183 Node* head = loop->_head;
2184 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2185 Node* use = n->fast_out(j);
2186 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2187 return true;
2188 }
2189 }
2190 return false;
2191 }
2192
2193
2194 //------------------------------ clone_for_use_outside_loop -------------------------------------
2195 // clone "n" for uses that are outside of loop
2196 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2197 int cloned = 0;
2198 assert(worklist.size() == 0, "should be empty");
2199 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2200 Node* use = n->fast_out(j);
2201 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2202 worklist.push(use);
2203 }
2204 }
2205 while( worklist.size() ) {
2206 Node *use = worklist.pop();
2207 if (!has_node(use) || use->in(0) == C->top()) continue;
2208 uint j;
2209 for (j = 0; j < use->req(); j++) {
2210 if (use->in(j) == n) break;
2211 }
2212 assert(j < use->req(), "must be there");
2213
2214 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2215 Node* n_clone = n->clone();
2216 _igvn.replace_input_of(use, j, n_clone);
2217 cloned++;
2218 Node* use_c;
2219 if (!use->is_Phi()) {
2220 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2221 } else {
2222 // Use in a phi is considered a use in the associated predecessor block
2223 use_c = use->in(0)->in(j);
2224 }
2225 set_ctrl(n_clone, use_c);
2226 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2227 get_loop(use_c)->_body.push(n_clone);
2228 _igvn.register_new_node_with_optimizer(n_clone);
2229 #if !defined(PRODUCT)
2230 if (TracePartialPeeling) {
2231 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2232 }
2233 #endif
2234 }
2235 return cloned;
2236 }
2237
2238
2239 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2240 // clone "n" for special uses that are in the not_peeled region.
2241 // If these def-uses occur in separate blocks, the code generator
2242 // marks the method as not compilable. For example, if a "BoolNode"
2243 // is in a different basic block than the "IfNode" that uses it, then
2244 // the compilation is aborted in the code generator.
2245 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2246 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2247 if (n->is_Phi() || n->is_Load()) {
2248 return;
2249 }
2250 assert(worklist.size() == 0, "should be empty");
2251 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2252 Node* use = n->fast_out(j);
2253 if ( not_peel.test(use->_idx) &&
2254 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2255 use->in(1) == n) {
2256 worklist.push(use);
2257 }
2258 }
2259 if (worklist.size() > 0) {
2260 // clone "n" and insert it between inputs of "n" and the use
2261 Node* n_clone = n->clone();
2262 loop->_body.push(n_clone);
2263 _igvn.register_new_node_with_optimizer(n_clone);
2264 set_ctrl(n_clone, get_ctrl(n));
2265 sink_list.push(n_clone);
2266 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2267 #if !defined(PRODUCT)
2268 if (TracePartialPeeling) {
2269 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2270 }
2271 #endif
2272 while( worklist.size() ) {
2273 Node *use = worklist.pop();
2274 _igvn.rehash_node_delayed(use);
2275 for (uint j = 1; j < use->req(); j++) {
2276 if (use->in(j) == n) {
2277 use->set_req(j, n_clone);
2278 }
2279 }
2280 }
2281 }
2282 }
2283
2284
2285 //------------------------------ insert_phi_for_loop -------------------------------------
2286 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2287 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2288 Node *phi = PhiNode::make(lp, back_edge_val);
2289 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2290 // Use existing phi if it already exists
2291 Node *hit = _igvn.hash_find_insert(phi);
2292 if( hit == NULL ) {
2293 _igvn.register_new_node_with_optimizer(phi);
2294 set_ctrl(phi, lp);
2295 } else {
2296 // Remove the new phi from the graph and use the hit
2297 _igvn.remove_dead_node(phi);
2298 phi = hit;
2299 }
2300 _igvn.replace_input_of(use, idx, phi);
2301 }
2302
2303 #ifdef ASSERT
2304 //------------------------------ is_valid_loop_partition -------------------------------------
2305 // Validate the loop partition sets: peel and not_peel
2306 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2307 VectorSet& not_peel ) {
2308 uint i;
2309 // Check that peel_list entries are in the peel set
2310 for (i = 0; i < peel_list.size(); i++) {
2311 if (!peel.test(peel_list.at(i)->_idx)) {
2312 return false;
2313 }
2314 }
2315 // Check at loop members are in one of peel set or not_peel set
2316 for (i = 0; i < loop->_body.size(); i++ ) {
2317 Node *def = loop->_body.at(i);
2318 uint di = def->_idx;
2319 // Check that peel set elements are in peel_list
2320 if (peel.test(di)) {
2321 if (not_peel.test(di)) {
2322 return false;
2323 }
2324 // Must be in peel_list also
2325 bool found = false;
2326 for (uint j = 0; j < peel_list.size(); j++) {
2327 if (peel_list.at(j)->_idx == di) {
2328 found = true;
2329 break;
2330 }
2331 }
2332 if (!found) {
2333 return false;
2334 }
2335 } else if (not_peel.test(di)) {
2336 if (peel.test(di)) {
2337 return false;
2338 }
2339 } else {
2340 return false;
2341 }
2342 }
2343 return true;
2344 }
2345
2346 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2347 // Ensure a use outside of loop is of the right form
2348 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2349 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2350 return (use->is_Phi() &&
2351 use_c->is_Region() && use_c->req() == 3 &&
2352 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2353 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2354 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2355 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2356 }
2357
2358 //------------------------------ is_valid_clone_loop_form -------------------------------------
2359 // Ensure that all uses outside of loop are of the right form
2360 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2361 uint orig_exit_idx, uint clone_exit_idx) {
2362 uint len = peel_list.size();
2363 for (uint i = 0; i < len; i++) {
2364 Node *def = peel_list.at(i);
2365
2366 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2367 Node *use = def->fast_out(j);
2368 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2369 if (!loop->is_member(get_loop(use_c))) {
2370 // use is not in the loop, check for correct structure
2371 if (use->in(0) == def) {
2372 // Okay
2373 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2374 return false;
2375 }
2376 }
2377 }
2378 }
2379 return true;
2380 }
2381 #endif
2382
2383 //------------------------------ partial_peel -------------------------------------
2384 // Partially peel (aka loop rotation) the top portion of a loop (called
2385 // the peel section below) by cloning it and placing one copy just before
2386 // the new loop head and the other copy at the bottom of the new loop.
2387 //
2388 // before after where it came from
2389 //
2390 // stmt1 stmt1
2391 // loop: stmt2 clone
2392 // stmt2 if condA goto exitA clone
2393 // if condA goto exitA new_loop: new
2394 // stmt3 stmt3 clone
2395 // if !condB goto loop if condB goto exitB clone
2396 // exitB: stmt2 orig
2397 // stmt4 if !condA goto new_loop orig
2398 // exitA: goto exitA
2399 // exitB:
2400 // stmt4
2401 // exitA:
2402 //
2403 // Step 1: find the cut point: an exit test on probable
2404 // induction variable.
2405 // Step 2: schedule (with cloning) operations in the peel
2406 // section that can be executed after the cut into
2407 // the section that is not peeled. This may need
2408 // to clone operations into exit blocks. For
2409 // instance, a reference to A[i] in the not-peel
2410 // section and a reference to B[i] in an exit block
2411 // may cause a left-shift of i by 2 to be placed
2412 // in the peel block. This step will clone the left
2413 // shift into the exit block and sink the left shift
2414 // from the peel to the not-peel section.
2415 // Step 3: clone the loop, retarget the control, and insert
2416 // phis for values that are live across the new loop
2417 // head. This is very dependent on the graph structure
2418 // from clone_loop. It creates region nodes for
2419 // exit control and associated phi nodes for values
2420 // flow out of the loop through that exit. The region
2421 // node is dominated by the clone's control projection.
2422 // So the clone's peel section is placed before the
2423 // new loop head, and the clone's not-peel section is
2424 // forms the top part of the new loop. The original
2425 // peel section forms the tail of the new loop.
2426 // Step 4: update the dominator tree and recompute the
2427 // dominator depth.
2428 //
2429 // orig
2430 //
2431 // stmt1
2432 // |
2433 // v
2434 // loop predicate
2435 // |
2436 // v
2437 // loop<----+
2438 // | |
2439 // stmt2 |
2440 // | |
2441 // v |
2442 // ifA |
2443 // / | |
2444 // v v |
2445 // false true ^ <-- last_peel
2446 // / | |
2447 // / ===|==cut |
2448 // / stmt3 | <-- first_not_peel
2449 // / | |
2450 // | v |
2451 // v ifB |
2452 // exitA: / \ |
2453 // / \ |
2454 // v v |
2455 // false true |
2456 // / \ |
2457 // / ----+
2458 // |
2459 // v
2460 // exitB:
2461 // stmt4
2462 //
2463 //
2464 // after clone loop
2465 //
2466 // stmt1
2467 // |
2468 // v
2469 // loop predicate
2470 // / \
2471 // clone / \ orig
2472 // / \
2473 // / \
2474 // v v
2475 // +---->loop loop<----+
2476 // | | | |
2477 // | stmt2 stmt2 |
2478 // | | | |
2479 // | v v |
2480 // | ifA ifA |
2481 // | | \ / | |
2482 // | v v v v |
2483 // ^ true false false true ^ <-- last_peel
2484 // | | ^ \ / | |
2485 // | cut==|== \ \ / ===|==cut |
2486 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2487 // | | dom | | | |
2488 // | v \ 1v v2 v |
2489 // | ifB regionA ifB |
2490 // | / \ | / \ |
2491 // | / \ v / \ |
2492 // | v v exitA: v v |
2493 // | true false false true |
2494 // | / ^ \ / \ |
2495 // +---- \ \ / ----+
2496 // dom \ /
2497 // \ 1v v2
2498 // regionB
2499 // |
2500 // v
2501 // exitB:
2502 // stmt4
2503 //
2504 //
2505 // after partial peel
2506 //
2507 // stmt1
2508 // |
2509 // v
2510 // loop predicate
2511 // /
2512 // clone / orig
2513 // / TOP
2514 // / \
2515 // v v
2516 // TOP->loop loop----+
2517 // | | |
2518 // stmt2 stmt2 |
2519 // | | |
2520 // v v |
2521 // ifA ifA |
2522 // | \ / | |
2523 // v v v v |
2524 // true false false true | <-- last_peel
2525 // | ^ \ / +------|---+
2526 // +->newloop \ \ / === ==cut | |
2527 // | stmt3 \ \ / TOP | |
2528 // | | dom | | stmt3 | | <-- first_not_peel
2529 // | v \ 1v v2 v | |
2530 // | ifB regionA ifB ^ v
2531 // | / \ | / \ | |
2532 // | / \ v / \ | |
2533 // | v v exitA: v v | |
2534 // | true false false true | |
2535 // | / ^ \ / \ | |
2536 // | | \ \ / v | |
2537 // | | dom \ / TOP | |
2538 // | | \ 1v v2 | |
2539 // ^ v regionB | |
2540 // | | | | |
2541 // | | v ^ v
2542 // | | exitB: | |
2543 // | | stmt4 | |
2544 // | +------------>-----------------+ |
2545 // | |
2546 // +-----------------<---------------------+
2547 //
2548 //
2549 // final graph
2550 //
2551 // stmt1
2552 // |
2553 // v
2554 // loop predicate
2555 // |
2556 // v
2557 // stmt2 clone
2558 // |
2559 // v
2560 // ........> ifA clone
2561 // : / |
2562 // dom / |
2563 // : v v
2564 // : false true
2565 // : | |
2566 // : | v
2567 // : | newloop<-----+
2568 // : | | |
2569 // : | stmt3 clone |
2570 // : | | |
2571 // : | v |
2572 // : | ifB |
2573 // : | / \ |
2574 // : | v v |
2575 // : | false true |
2576 // : | | | |
2577 // : | v stmt2 |
2578 // : | exitB: | |
2579 // : | stmt4 v |
2580 // : | ifA orig |
2581 // : | / \ |
2582 // : | / \ |
2583 // : | v v |
2584 // : | false true |
2585 // : | / \ |
2586 // : v v -----+
2587 // RegionA
2588 // |
2589 // v
2590 // exitA
2591 //
2592 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2593
2594 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2595 if (!loop->_head->is_Loop()) {
2596 return false; }
2597
2598 LoopNode *head = loop->_head->as_Loop();
2599
2600 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2601 return false;
2602 }
2603
2604 // Check for complex exit control
2605 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2606 Node *n = loop->_body.at(ii);
2607 int opc = n->Opcode();
2608 if (n->is_Call() ||
2609 opc == Op_Catch ||
2610 opc == Op_CatchProj ||
2611 opc == Op_Jump ||
2612 opc == Op_JumpProj) {
2613 #if !defined(PRODUCT)
2614 if (TracePartialPeeling) {
2615 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2616 }
2617 #endif
2618 return false;
2619 }
2620 }
2621
2622 int dd = dom_depth(head);
2623
2624 // Step 1: find cut point
2625
2626 // Walk up dominators to loop head looking for first loop exit
2627 // which is executed on every path thru loop.
2628 IfNode *peel_if = NULL;
2629 IfNode *peel_if_cmpu = NULL;
2630
2631 Node *iff = loop->tail();
2632 while( iff != head ) {
2633 if( iff->is_If() ) {
2634 Node *ctrl = get_ctrl(iff->in(1));
2635 if (ctrl->is_top()) return false; // Dead test on live IF.
2636 // If loop-varying exit-test, check for induction variable
2637 if( loop->is_member(get_loop(ctrl)) &&
2638 loop->is_loop_exit(iff) &&
2639 is_possible_iv_test(iff)) {
2640 Node* cmp = iff->in(1)->in(1);
2641 if (cmp->Opcode() == Op_CmpI) {
2642 peel_if = iff->as_If();
2643 } else {
2644 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2645 peel_if_cmpu = iff->as_If();
2646 }
2647 }
2648 }
2649 iff = idom(iff);
2650 }
2651 // Prefer signed compare over unsigned compare.
2652 IfNode* new_peel_if = NULL;
2653 if (peel_if == NULL) {
2654 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2655 return false; // No peel point found
2656 }
2657 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2658 if (new_peel_if == NULL) {
2659 return false; // No peel point found
2660 }
2661 peel_if = new_peel_if;
2662 }
2663 Node* last_peel = stay_in_loop(peel_if, loop);
2664 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2665 if (first_not_peeled == NULL || first_not_peeled == head) {
2666 return false;
2667 }
2668
2669 #if !defined(PRODUCT)
2670 if (TraceLoopOpts) {
2671 tty->print("PartialPeel ");
2672 loop->dump_head();
2673 }
2674
2675 if (TracePartialPeeling) {
2676 tty->print_cr("before partial peel one iteration");
2677 Node_List wl;
2678 Node* t = head->in(2);
2679 while (true) {
2680 wl.push(t);
2681 if (t == head) break;
2682 t = idom(t);
2683 }
2684 while (wl.size() > 0) {
2685 Node* tt = wl.pop();
2686 tt->dump();
2687 if (tt == last_peel) tty->print_cr("-- cut --");
2688 }
2689 }
2690 #endif
2691 ResourceArea *area = Thread::current()->resource_area();
2692 VectorSet peel(area);
2693 VectorSet not_peel(area);
2694 Node_List peel_list(area);
2695 Node_List worklist(area);
2696 Node_List sink_list(area);
2697
2698 // Set of cfg nodes to peel are those that are executable from
2699 // the head through last_peel.
2700 assert(worklist.size() == 0, "should be empty");
2701 worklist.push(head);
2702 peel.set(head->_idx);
2703 while (worklist.size() > 0) {
2704 Node *n = worklist.pop();
2705 if (n != last_peel) {
2706 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2707 Node* use = n->fast_out(j);
2708 if (use->is_CFG() &&
2709 loop->is_member(get_loop(use)) &&
2710 !peel.test_set(use->_idx)) {
2711 worklist.push(use);
2712 }
2713 }
2714 }
2715 }
2716
2717 // Set of non-cfg nodes to peel are those that are control
2718 // dependent on the cfg nodes.
2719 uint i;
2720 for(i = 0; i < loop->_body.size(); i++ ) {
2721 Node *n = loop->_body.at(i);
2722 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2723 if (peel.test(n_c->_idx)) {
2724 peel.set(n->_idx);
2725 } else {
2726 not_peel.set(n->_idx);
2727 }
2728 }
2729
2730 // Step 2: move operations from the peeled section down into the
2731 // not-peeled section
2732
2733 // Get a post order schedule of nodes in the peel region
2734 // Result in right-most operand.
2735 scheduled_nodelist(loop, peel, peel_list );
2736
2737 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2738
2739 // For future check for too many new phis
2740 uint old_phi_cnt = 0;
2741 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2742 Node* use = head->fast_out(j);
2743 if (use->is_Phi()) old_phi_cnt++;
2744 }
2745
2746 #if !defined(PRODUCT)
2747 if (TracePartialPeeling) {
2748 tty->print_cr("\npeeled list");
2749 }
2750 #endif
2751
2752 // Evacuate nodes in peel region into the not_peeled region if possible
2753 uint new_phi_cnt = 0;
2754 uint cloned_for_outside_use = 0;
2755 for (i = 0; i < peel_list.size();) {
2756 Node* n = peel_list.at(i);
2757 #if !defined(PRODUCT)
2758 if (TracePartialPeeling) n->dump();
2759 #endif
2760 bool incr = true;
2761 if ( !n->is_CFG() ) {
2762
2763 if ( has_use_in_set(n, not_peel) ) {
2764
2765 // If not used internal to the peeled region,
2766 // move "n" from peeled to not_peeled region.
2767
2768 if ( !has_use_internal_to_set(n, peel, loop) ) {
2769
2770 // if not pinned and not a load (which maybe anti-dependent on a store)
2771 // and not a CMove (Matcher expects only bool->cmove).
2772 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2773 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2774 sink_list.push(n);
2775 peel >>= n->_idx; // delete n from peel set.
2776 not_peel <<= n->_idx; // add n to not_peel set.
2777 peel_list.remove(i);
2778 incr = false;
2779 #if !defined(PRODUCT)
2780 if (TracePartialPeeling) {
2781 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2782 n->_idx, get_ctrl(n)->_idx);
2783 }
2784 #endif
2785 }
2786 } else {
2787 // Otherwise check for special def-use cases that span
2788 // the peel/not_peel boundary such as bool->if
2789 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2790 new_phi_cnt++;
2791 }
2792 }
2793 }
2794 if (incr) i++;
2795 }
2796
2797 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2798 #if !defined(PRODUCT)
2799 if (TracePartialPeeling) {
2800 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2801 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2802 }
2803 #endif
2804 if (new_peel_if != NULL) {
2805 remove_cmpi_loop_exit(new_peel_if, loop);
2806 }
2807 // Inhibit more partial peeling on this loop
2808 assert(!head->is_partial_peel_loop(), "not partial peeled");
2809 head->mark_partial_peel_failed();
2810 if (cloned_for_outside_use > 0) {
2811 // Terminate this round of loop opts because
2812 // the graph outside this loop was changed.
2813 C->set_major_progress();
2814 return true;
2815 }
2816 return false;
2817 }
2818
2819 // Step 3: clone loop, retarget control, and insert new phis
2820
2821 // Create new loop head for new phis and to hang
2822 // the nodes being moved (sinked) from the peel region.
2823 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2824 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2825 _igvn.register_new_node_with_optimizer(new_head);
2826 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2827 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2828 set_loop(new_head, loop);
2829 loop->_body.push(new_head);
2830 not_peel.set(new_head->_idx);
2831 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2832 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2833
2834 while (sink_list.size() > 0) {
2835 Node* n = sink_list.pop();
2836 set_ctrl(n, new_head);
2837 }
2838
2839 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2840
2841 clone_loop( loop, old_new, dd );
2842
2843 const uint clone_exit_idx = 1;
2844 const uint orig_exit_idx = 2;
2845 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2846
2847 Node* head_clone = old_new[head->_idx];
2848 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2849 Node* orig_tail_clone = head_clone->in(2);
2850
2851 // Add phi if "def" node is in peel set and "use" is not
2852
2853 for(i = 0; i < peel_list.size(); i++ ) {
2854 Node *def = peel_list.at(i);
2855 if (!def->is_CFG()) {
2856 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2857 Node *use = def->fast_out(j);
2858 if (has_node(use) && use->in(0) != C->top() &&
2859 (!peel.test(use->_idx) ||
2860 (use->is_Phi() && use->in(0) == head)) ) {
2861 worklist.push(use);
2862 }
2863 }
2864 while( worklist.size() ) {
2865 Node *use = worklist.pop();
2866 for (uint j = 1; j < use->req(); j++) {
2867 Node* n = use->in(j);
2868 if (n == def) {
2869
2870 // "def" is in peel set, "use" is not in peel set
2871 // or "use" is in the entry boundary (a phi) of the peel set
2872
2873 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2874
2875 if ( loop->is_member(get_loop( use_c )) ) {
2876 // use is in loop
2877 if (old_new[use->_idx] != NULL) { // null for dead code
2878 Node* use_clone = old_new[use->_idx];
2879 _igvn.replace_input_of(use, j, C->top());
2880 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2881 }
2882 } else {
2883 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2884 // use is not in the loop, check if the live range includes the cut
2885 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2886 if (not_peel.test(lp_if->_idx)) {
2887 assert(j == orig_exit_idx, "use from original loop");
2888 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2889 }
2890 }
2891 }
2892 }
2893 }
2894 }
2895 }
2896
2897 // Step 3b: retarget control
2898
2899 // Redirect control to the new loop head if a cloned node in
2900 // the not_peeled region has control that points into the peeled region.
2901 // This necessary because the cloned peeled region will be outside
2902 // the loop.
2903 // from to
2904 // cloned-peeled <---+
2905 // new_head_clone: | <--+
2906 // cloned-not_peeled in(0) in(0)
2907 // orig-peeled
2908
2909 for(i = 0; i < loop->_body.size(); i++ ) {
2910 Node *n = loop->_body.at(i);
2911 if (!n->is_CFG() && n->in(0) != NULL &&
2912 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2913 Node* n_clone = old_new[n->_idx];
2914 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2915 }
2916 }
2917
2918 // Backedge of the surviving new_head (the clone) is original last_peel
2919 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2920
2921 // Cut first node in original not_peel set
2922 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2923 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2924 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2925
2926 // Copy head_clone back-branch info to original head
2927 // and remove original head's loop entry and
2928 // clone head's back-branch
2929 _igvn.rehash_node_delayed(head); // Multiple edge updates
2930 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2931 head->set_req(LoopNode::LoopBackControl, C->top());
2932 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2933
2934 // Similarly modify the phis
2935 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2936 Node* use = head->fast_out(k);
2937 if (use->is_Phi() && use->outcnt() > 0) {
2938 Node* use_clone = old_new[use->_idx];
2939 _igvn.rehash_node_delayed(use); // Multiple edge updates
2940 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2941 use->set_req(LoopNode::LoopBackControl, C->top());
2942 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2943 }
2944 }
2945
2946 // Step 4: update dominator tree and dominator depth
2947
2948 set_idom(head, orig_tail_clone, dd);
2949 recompute_dom_depth();
2950
2951 // Inhibit more partial peeling on this loop
2952 new_head_clone->set_partial_peel_loop();
2953 C->set_major_progress();
2954 loop->record_for_igvn();
2955
2956 #if !defined(PRODUCT)
2957 if (TracePartialPeeling) {
2958 tty->print_cr("\nafter partial peel one iteration");
2959 Node_List wl(area);
2960 Node* t = last_peel;
2961 while (true) {
2962 wl.push(t);
2963 if (t == head_clone) break;
2964 t = idom(t);
2965 }
2966 while (wl.size() > 0) {
2967 Node* tt = wl.pop();
2968 if (tt == head) tty->print_cr("orig head");
2969 else if (tt == new_head_clone) tty->print_cr("new head");
2970 else if (tt == head_clone) tty->print_cr("clone head");
2971 tt->dump();
2972 }
2973 }
2974 #endif
2975 return true;
2976 }
2977
2978 //------------------------------reorg_offsets----------------------------------
2979 // Reorganize offset computations to lower register pressure. Mostly
2980 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2981 // then alive with the post-incremented trip counter forcing an extra
2982 // register move)
2983 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2984 // Perform it only for canonical counted loops.
2985 // Loop's shape could be messed up by iteration_split_impl.
2986 if (!loop->_head->is_CountedLoop())
2987 return;
2988 if (!loop->_head->as_Loop()->is_valid_counted_loop())
2989 return;
2990
2991 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2992 CountedLoopEndNode *cle = cl->loopexit();
2993 Node *exit = cle->proj_out(false);
2994 Node *phi = cl->phi();
2995
2996 // Check for the special case of folks using the pre-incremented
2997 // trip-counter on the fall-out path (forces the pre-incremented
2998 // and post-incremented trip counter to be live at the same time).
2999 // Fix this by adjusting to use the post-increment trip counter.
3000
3001 bool progress = true;
3002 while (progress) {
3003 progress = false;
3004 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3005 Node* use = phi->fast_out(i); // User of trip-counter
3006 if (!has_ctrl(use)) continue;
3007 Node *u_ctrl = get_ctrl(use);
3008 if (use->is_Phi()) {
3009 u_ctrl = NULL;
3010 for (uint j = 1; j < use->req(); j++)
3011 if (use->in(j) == phi)
3012 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3013 }
3014 IdealLoopTree *u_loop = get_loop(u_ctrl);
3015 // Look for loop-invariant use
3016 if (u_loop == loop) continue;
3017 if (loop->is_member(u_loop)) continue;
3018 // Check that use is live out the bottom. Assuming the trip-counter
3019 // update is right at the bottom, uses of of the loop middle are ok.
3020 if (dom_lca(exit, u_ctrl) != exit) continue;
3021 // Hit! Refactor use to use the post-incremented tripcounter.
3022 // Compute a post-increment tripcounter.
3023 Node *opaq = new Opaque2Node( C, cle->incr() );
3024 register_new_node(opaq, exit);
3025 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3026 set_ctrl(neg_stride, C->root());
3027 Node *post = new AddINode( opaq, neg_stride);
3028 register_new_node(post, exit);
3029 _igvn.rehash_node_delayed(use);
3030 for (uint j = 1; j < use->req(); j++) {
3031 if (use->in(j) == phi)
3032 use->set_req(j, post);
3033 }
3034 // Since DU info changed, rerun loop
3035 progress = true;
3036 break;
3037 }
3038 }
3039
3040 }