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 || iff->Opcode() == Op_RangeCheck, "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_DOUBLE:
516 if (C->use_cmove()) {
517 continue; //TODO: maybe we want to add some cost
518 }
519 case T_FLOAT: {
520 cost += Matcher::float_cmove_cost(); // Could be very expensive
521 break;
522 }
523 case T_LONG: {
524 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
525 }
526 case T_INT: // These all CMOV fine
527 case T_ADDRESS: { // (RawPtr)
528 cost++;
529 break;
530 }
531 case T_NARROWOOP: // Fall through
532 case T_OBJECT: { // Base oops are OK, but not derived oops
533 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
534 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
535 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
536 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
537 // have a Phi for the base here that we convert to a CMOVE all is well
538 // and good. But if the base is dead, we'll not make a CMOVE. Later
539 // the allocator will have to produce a base by creating a CMOVE of the
540 // relevant bases. This puts the allocator in the business of
541 // manufacturing expensive instructions, generally a bad plan.
542 // Just Say No to Conditionally-Moved Derived Pointers.
543 if (tp && tp->offset() != 0)
544 return NULL;
545 cost++;
546 break;
547 }
548 default:
549 return NULL; // In particular, can't do memory or I/O
550 }
551 // Add in cost any speculative ops
552 for (uint j = 1; j < region->req(); j++) {
553 Node *proj = region->in(j);
554 Node *inp = phi->in(j);
555 if (get_ctrl(inp) == proj) { // Found local op
556 cost++;
557 // Check for a chain of dependent ops; these will all become
558 // speculative in a CMOV.
559 for (uint k = 1; k < inp->req(); k++)
560 if (get_ctrl(inp->in(k)) == proj)
561 cost += ConditionalMoveLimit; // Too much speculative goo
562 }
563 }
564 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
565 // This will likely Split-If, a higher-payoff operation.
566 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
567 Node* use = phi->fast_out(k);
568 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
569 cost += ConditionalMoveLimit;
570 // Is there a use inside the loop?
571 // Note: check only basic types since CMoveP is pinned.
572 if (!used_inside_loop && is_java_primitive(bt)) {
573 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
574 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
575 used_inside_loop = true;
576 }
577 }
578 }
579 }//for
580 Node* bol = iff->in(1);
581 assert(bol->Opcode() == Op_Bool, "");
582 int cmp_op = bol->in(1)->Opcode();
583 // It is expensive to generate flags from a float compare.
584 // Avoid duplicated float compare.
585 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
586
587 float infrequent_prob = PROB_UNLIKELY_MAG(3);
588 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
589 if (used_inside_loop) {
590 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
591
592 // BlockLayoutByFrequency optimization moves infrequent branch
593 // from hot path. No point in CMOV'ing in such case (110 is used
594 // instead of 100 to take into account not exactness of float value).
595 if (BlockLayoutByFrequency) {
596 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
597 }
598 }
599 // Check for highly predictable branch. No point in CMOV'ing if
600 // we are going to predict accurately all the time.
601 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
602 else if (iff->_prob < infrequent_prob ||
603 iff->_prob > (1.0f - infrequent_prob))
604 return NULL;
605
606 // --------------
607 // Now replace all Phis with CMOV's
608 Node *cmov_ctrl = iff->in(0);
609 uint flip = (lp->Opcode() == Op_IfTrue);
610 while (1) {
611 PhiNode* phi = NULL;
612 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
613 Node *out = region->fast_out(i);
614 if (out->is_Phi()) {
615 phi = out->as_Phi();
616 break;
617 }
618 }
619 if (phi == NULL) break;
620 #ifndef PRODUCT
621 if (PrintOpto && VerifyLoopOptimizations) tty->print_cr("CMOV");
622 #endif
623 // Move speculative ops
624 for (uint j = 1; j < region->req(); j++) {
625 Node *proj = region->in(j);
626 Node *inp = phi->in(j);
627 if (get_ctrl(inp) == proj) { // Found local op
628 #ifndef PRODUCT
629 if (PrintOpto && VerifyLoopOptimizations) {
630 tty->print(" speculate: ");
631 inp->dump();
632 }
633 #endif
634 set_ctrl(inp, cmov_ctrl);
635 }
636 }
637 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
638 register_new_node( cmov, cmov_ctrl );
639 _igvn.replace_node( phi, cmov );
640 #ifndef PRODUCT
641 if (TraceLoopOpts) {
642 tty->print("CMOV ");
643 r_loop->dump_head();
644 if (Verbose) {
645 bol->in(1)->dump(1);
646 cmov->dump(1);
647 }
648 }
649 if (VerifyLoopOptimizations) verify();
650 #endif
651 }
652
653 // The useless CFG diamond will fold up later; see the optimization in
654 // RegionNode::Ideal.
655 _igvn._worklist.push(region);
656
657 return iff->in(1);
658 }
659
660 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
661 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
662 Node* u = m->fast_out(i);
663 if (u->is_CFG()) {
664 if (u->Opcode() == Op_NeverBranch) {
665 u = ((NeverBranchNode*)u)->proj_out(0);
666 enqueue_cfg_uses(u, wq);
667 } else {
668 wq.push(u);
669 }
670 }
671 }
672 }
673
674 // Try moving a store out of a loop, right before the loop
675 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
676 // Store has to be first in the loop body
677 IdealLoopTree *n_loop = get_loop(n_ctrl);
678 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
679 Node* address = n->in(MemNode::Address);
680 Node* value = n->in(MemNode::ValueIn);
681 Node* mem = n->in(MemNode::Memory);
682 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
683 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
684
685 // - address and value must be loop invariant
686 // - memory must be a memory Phi for the loop
687 // - Store must be the only store on this memory slice in the
688 // loop: if there's another store following this one then value
689 // written at iteration i by the second store could be overwritten
690 // at iteration i+n by the first store: it's not safe to move the
691 // first store out of the loop
692 // - nothing must observe the memory Phi: it guarantees no read
693 // before the store, we are also guaranteed the store post
694 // dominates the loop head (ignoring a possible early
695 // exit). Otherwise there would be extra Phi involved between the
696 // loop's Phi and the store.
697 // - there must be no early exit from the loop before the Store
698 // (such an exit most of the time would be an extra use of the
699 // memory Phi but sometimes is a bottom memory Phi that takes the
700 // store as input).
701
702 if (!n_loop->is_member(address_loop) &&
703 !n_loop->is_member(value_loop) &&
704 mem->is_Phi() && mem->in(0) == n_loop->_head &&
705 mem->outcnt() == 1 &&
706 mem->in(LoopNode::LoopBackControl) == n) {
707
708 assert(n_loop->_tail != NULL, "need a tail");
709 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
710
711 // Verify that there's no early exit of the loop before the store.
712 bool ctrl_ok = false;
713 {
714 // Follow control from loop head until n, we exit the loop or
715 // we reach the tail
716 ResourceMark rm;
717 Unique_Node_List wq;
718 wq.push(n_loop->_head);
719
720 for (uint next = 0; next < wq.size(); ++next) {
721 Node *m = wq.at(next);
722 if (m == n->in(0)) {
723 ctrl_ok = true;
724 continue;
725 }
726 assert(!has_ctrl(m), "should be CFG");
727 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
728 ctrl_ok = false;
729 break;
730 }
731 enqueue_cfg_uses(m, wq);
732 if (wq.size() > 10) {
733 ctrl_ok = false;
734 break;
735 }
736 }
737 }
738 if (ctrl_ok) {
739 // move the Store
740 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
741 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
742 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
743 // Disconnect the phi now. An empty phi can confuse other
744 // optimizations in this pass of loop opts.
745 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
746 n_loop->_body.yank(mem);
747
748 IdealLoopTree* new_loop = get_loop(n->in(0));
749 set_ctrl_and_loop(n, n->in(0));
750
751 return n;
752 }
753 }
754 }
755 return NULL;
756 }
757
758 // Try moving a store out of a loop, right after the loop
759 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
760 if (n->is_Store() && n->in(0) != NULL) {
761 Node *n_ctrl = get_ctrl(n);
762 IdealLoopTree *n_loop = get_loop(n_ctrl);
763 // Store must be in a loop
764 if (n_loop != _ltree_root && !n_loop->_irreducible) {
765 Node* address = n->in(MemNode::Address);
766 Node* value = n->in(MemNode::ValueIn);
767 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
768 // address must be loop invariant
769 if (!n_loop->is_member(address_loop)) {
770 // Store must be last on this memory slice in the loop and
771 // nothing in the loop must observe it
772 Node* phi = NULL;
773 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
774 Node* u = n->fast_out(i);
775 if (has_ctrl(u)) { // control use?
776 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
777 if (!n_loop->is_member(u_loop)) {
778 continue;
779 }
780 if (u->is_Phi() && u->in(0) == n_loop->_head) {
781 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
782 // multiple phis on the same slice are possible
783 if (phi != NULL) {
784 return;
785 }
786 phi = u;
787 continue;
788 }
789 }
790 return;
791 }
792 if (phi != NULL) {
793 // Nothing in the loop before the store (next iteration)
794 // must observe the stored value
795 bool mem_ok = true;
796 {
797 ResourceMark rm;
798 Unique_Node_List wq;
799 wq.push(phi);
800 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
801 Node *m = wq.at(next);
802 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
803 Node* u = m->fast_out(i);
804 if (u->is_Store() || u->is_Phi()) {
805 if (u != n) {
806 wq.push(u);
807 mem_ok = (wq.size() <= 10);
808 }
809 } else {
810 mem_ok = false;
811 break;
812 }
813 }
814 }
815 }
816 if (mem_ok) {
817 // Move the Store out of the loop creating clones along
818 // all paths out of the loop that observe the stored value
819 _igvn.rehash_node_delayed(phi);
820 int count = phi->replace_edge(n, n->in(MemNode::Memory));
821 assert(count > 0, "inconsistent phi");
822 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
823 Node* u = n->fast_out(i);
824 Node* c = get_ctrl(u);
825
826 if (u->is_Phi()) {
827 c = u->in(0)->in(u->find_edge(n));
828 }
829 IdealLoopTree *u_loop = get_loop(c);
830 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
831 while(true) {
832 Node* next_c = find_non_split_ctrl(idom(c));
833 if (n_loop->is_member(get_loop(next_c))) {
834 break;
835 }
836 c = next_c;
837 }
838
839 Node* st = n->clone();
840 st->set_req(0, c);
841 _igvn.register_new_node_with_optimizer(st);
842
843 set_ctrl(st, c);
844 IdealLoopTree* new_loop = get_loop(c);
845 assert(new_loop != n_loop, "should be moved out of loop");
846 if (new_loop->_child == NULL) new_loop->_body.push(st);
847
848 _igvn.replace_input_of(u, u->find_edge(n), st);
849 --imax;
850 --i;
851 }
852
853
854 assert(n->outcnt() == 0, "all uses should be gone");
855 _igvn.replace_input_of(n, MemNode::Memory, C->top());
856 // Disconnect the phi now. An empty phi can confuse other
857 // optimizations in this pass of loop opts..
858 if (phi->in(LoopNode::LoopBackControl) == phi) {
859 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
860 n_loop->_body.yank(phi);
861 }
862 }
863 }
864 }
865 }
866 }
867 }
868
869 //------------------------------split_if_with_blocks_pre-----------------------
870 // Do the real work in a non-recursive function. Data nodes want to be
871 // cloned in the pre-order so they can feed each other nicely.
872 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
873 // Cloning these guys is unlikely to win
874 int n_op = n->Opcode();
875 if( n_op == Op_MergeMem ) return n;
876 if( n->is_Proj() ) return n;
877 // Do not clone-up CmpFXXX variations, as these are always
878 // followed by a CmpI
879 if( n->is_Cmp() ) return n;
880 // Attempt to use a conditional move instead of a phi/branch
881 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
882 Node *cmov = conditional_move( n );
883 if( cmov ) return cmov;
884 }
885 if( n->is_CFG() || n->is_LoadStore() )
886 return n;
887 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
888 n_op == Op_Opaque2 ) {
889 if( !C->major_progress() ) // If chance of no more loop opts...
890 _igvn._worklist.push(n); // maybe we'll remove them
891 return n;
892 }
893
894 if( n->is_Con() ) return n; // No cloning for Con nodes
895
896 Node *n_ctrl = get_ctrl(n);
897 if( !n_ctrl ) return n; // Dead node
898
899 Node* res = try_move_store_before_loop(n, n_ctrl);
900 if (res != NULL) {
901 return n;
902 }
903
904 // Attempt to remix address expressions for loop invariants
905 Node *m = remix_address_expressions( n );
906 if( m ) return m;
907
908 // Determine if the Node has inputs from some local Phi.
909 // Returns the block to clone thru.
910 Node *n_blk = has_local_phi_input( n );
911 if( !n_blk ) return n;
912
913 // Do not clone the trip counter through on a CountedLoop
914 // (messes up the canonical shape).
915 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
916
917 // Check for having no control input; not pinned. Allow
918 // dominating control.
919 if (n->in(0)) {
920 Node *dom = idom(n_blk);
921 if (dom_lca(n->in(0), dom) != n->in(0)) {
922 return n;
923 }
924 }
925 // Policy: when is it profitable. You must get more wins than
926 // policy before it is considered profitable. Policy is usually 0,
927 // so 1 win is considered profitable. Big merges will require big
928 // cloning, so get a larger policy.
929 int policy = n_blk->req() >> 2;
930
931 // If the loop is a candidate for range check elimination,
932 // delay splitting through it's phi until a later loop optimization
933 if (n_blk->is_CountedLoop()) {
934 IdealLoopTree *lp = get_loop(n_blk);
935 if (lp && lp->_rce_candidate) {
936 return n;
937 }
938 }
939
940 // Use same limit as split_if_with_blocks_post
941 if( C->live_nodes() > 35000 ) return n; // Method too big
942
943 // Split 'n' through the merge point if it is profitable
944 Node *phi = split_thru_phi( n, n_blk, policy );
945 if (!phi) return n;
946
947 // Found a Phi to split thru!
948 // Replace 'n' with the new phi
949 _igvn.replace_node( n, phi );
950 // Moved a load around the loop, 'en-registering' something.
951 if (n_blk->is_Loop() && n->is_Load() &&
952 !phi->in(LoopNode::LoopBackControl)->is_Load())
953 C->set_major_progress();
954
955 return phi;
956 }
957
958 static bool merge_point_too_heavy(Compile* C, Node* region) {
959 // Bail out if the region and its phis have too many users.
960 int weight = 0;
961 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
962 weight += region->fast_out(i)->outcnt();
963 }
964 int nodes_left = C->max_node_limit() - C->live_nodes();
965 if (weight * 8 > nodes_left) {
966 #ifndef PRODUCT
967 if (PrintOpto)
968 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
969 #endif
970 return true;
971 } else {
972 return false;
973 }
974 }
975
976 static bool merge_point_safe(Node* region) {
977 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
978 // having a PhiNode input. This sidesteps the dangerous case where the split
979 // ConvI2LNode may become TOP if the input Value() does not
980 // overlap the ConvI2L range, leaving a node which may not dominate its
981 // uses.
982 // A better fix for this problem can be found in the BugTraq entry, but
983 // expediency for Mantis demands this hack.
984 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
985 // split_if_with_blocks from splitting a block because we could not move around
986 // the FastLockNode.
987 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
988 Node* n = region->fast_out(i);
989 if (n->is_Phi()) {
990 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
991 Node* m = n->fast_out(j);
992 if (m->is_FastLock())
993 return false;
994 #ifdef _LP64
995 if (m->Opcode() == Op_ConvI2L)
996 return false;
997 #endif
998 }
999 }
1000 }
1001 return true;
1002 }
1003
1004
1005 //------------------------------place_near_use---------------------------------
1006 // Place some computation next to use but not inside inner loops.
1007 // For inner loop uses move it to the preheader area.
1008 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1009 IdealLoopTree *u_loop = get_loop( useblock );
1010 return (u_loop->_irreducible || u_loop->_child)
1011 ? useblock
1012 : u_loop->_head->in(LoopNode::EntryControl);
1013 }
1014
1015
1016 //------------------------------split_if_with_blocks_post----------------------
1017 // Do the real work in a non-recursive function. CFG hackery wants to be
1018 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1019 // info.
1020 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1021
1022 // Cloning Cmp through Phi's involves the split-if transform.
1023 // FastLock is not used by an If
1024 if( n->is_Cmp() && !n->is_FastLock() ) {
1025 if( C->live_nodes() > 35000 ) return; // Method too big
1026
1027 // Do not do 'split-if' if irreducible loops are present.
1028 if( _has_irreducible_loops )
1029 return;
1030
1031 Node *n_ctrl = get_ctrl(n);
1032 // Determine if the Node has inputs from some local Phi.
1033 // Returns the block to clone thru.
1034 Node *n_blk = has_local_phi_input( n );
1035 if( n_blk != n_ctrl ) return;
1036
1037 if( merge_point_too_heavy(C, n_ctrl) )
1038 return;
1039
1040 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1041 Node *bol = n->unique_out();
1042 assert( bol->is_Bool(), "expect a bool here" );
1043 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1044 Node *iff = bol->unique_out();
1045
1046 // Check some safety conditions
1047 if( iff->is_If() ) { // Classic split-if?
1048 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1049 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1050 // Can't split CMove with different control edge.
1051 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1052 if( get_ctrl(iff->in(2)) == n_ctrl ||
1053 get_ctrl(iff->in(3)) == n_ctrl )
1054 return; // Inputs not yet split-up
1055 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1056 return; // Loop-invar test gates loop-varying CMOVE
1057 }
1058 } else {
1059 return; // some other kind of node, such as an Allocate
1060 }
1061
1062 // Do not do 'split-if' if some paths are dead. First do dead code
1063 // elimination and then see if its still profitable.
1064 for( uint i = 1; i < n_ctrl->req(); i++ )
1065 if( n_ctrl->in(i) == C->top() )
1066 return;
1067
1068 // When is split-if profitable? Every 'win' on means some control flow
1069 // goes dead, so it's almost always a win.
1070 int policy = 0;
1071 // If trying to do a 'Split-If' at the loop head, it is only
1072 // profitable if the cmp folds up on BOTH paths. Otherwise we
1073 // risk peeling a loop forever.
1074
1075 // CNC - Disabled for now. Requires careful handling of loop
1076 // body selection for the cloned code. Also, make sure we check
1077 // for any input path not being in the same loop as n_ctrl. For
1078 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1079 // because the alternative loop entry points won't be converted
1080 // into LoopNodes.
1081 IdealLoopTree *n_loop = get_loop(n_ctrl);
1082 for( uint j = 1; j < n_ctrl->req(); j++ )
1083 if( get_loop(n_ctrl->in(j)) != n_loop )
1084 return;
1085
1086 // Check for safety of the merge point.
1087 if( !merge_point_safe(n_ctrl) ) {
1088 return;
1089 }
1090
1091 // Split compare 'n' through the merge point if it is profitable
1092 Node *phi = split_thru_phi( n, n_ctrl, policy );
1093 if( !phi ) return;
1094
1095 // Found a Phi to split thru!
1096 // Replace 'n' with the new phi
1097 _igvn.replace_node( n, phi );
1098
1099 // Now split the bool up thru the phi
1100 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1101 guarantee(bolphi != NULL, "null boolean phi node");
1102
1103 _igvn.replace_node( bol, bolphi );
1104 assert( iff->in(1) == bolphi, "" );
1105
1106 if( bolphi->Value(&_igvn)->singleton() )
1107 return;
1108
1109 // Conditional-move? Must split up now
1110 if( !iff->is_If() ) {
1111 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1112 _igvn.replace_node( iff, cmovphi );
1113 return;
1114 }
1115
1116 // Now split the IF
1117 do_split_if( iff );
1118 return;
1119 }
1120
1121 // Check for an IF ready to split; one that has its
1122 // condition codes input coming from a Phi at the block start.
1123 int n_op = n->Opcode();
1124
1125 // Check for an IF being dominated by another IF same test
1126 if (n_op == Op_If ||
1127 n_op == Op_RangeCheck) {
1128 Node *bol = n->in(1);
1129 uint max = bol->outcnt();
1130 // Check for same test used more than once?
1131 if (max > 1 && bol->is_Bool()) {
1132 // Search up IDOMs to see if this IF is dominated.
1133 Node *cutoff = get_ctrl(bol);
1134
1135 // Now search up IDOMs till cutoff, looking for a dominating test
1136 Node *prevdom = n;
1137 Node *dom = idom(prevdom);
1138 while (dom != cutoff) {
1139 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1140 // Replace the dominated test with an obvious true or false.
1141 // Place it on the IGVN worklist for later cleanup.
1142 C->set_major_progress();
1143 dominated_by(prevdom, n, false, true);
1144 #ifndef PRODUCT
1145 if( VerifyLoopOptimizations ) verify();
1146 #endif
1147 return;
1148 }
1149 prevdom = dom;
1150 dom = idom(prevdom);
1151 }
1152 }
1153 }
1154
1155 // See if a shared loop-varying computation has no loop-varying uses.
1156 // Happens if something is only used for JVM state in uncommon trap exits,
1157 // like various versions of induction variable+offset. Clone the
1158 // computation per usage to allow it to sink out of the loop.
1159 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1160 Node *n_ctrl = get_ctrl(n);
1161 IdealLoopTree *n_loop = get_loop(n_ctrl);
1162 if( n_loop != _ltree_root ) {
1163 DUIterator_Fast imax, i = n->fast_outs(imax);
1164 for (; i < imax; i++) {
1165 Node* u = n->fast_out(i);
1166 if( !has_ctrl(u) ) break; // Found control user
1167 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1168 if( u_loop == n_loop ) break; // Found loop-varying use
1169 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1170 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1171 }
1172 bool did_break = (i < imax); // Did we break out of the previous loop?
1173 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1174 Node *late_load_ctrl = NULL;
1175 if (n->is_Load()) {
1176 // If n is a load, get and save the result from get_late_ctrl(),
1177 // to be later used in calculating the control for n's clones.
1178 clear_dom_lca_tags();
1179 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1180 }
1181 // If n is a load, and the late control is the same as the current
1182 // control, then the cloning of n is a pointless exercise, because
1183 // GVN will ensure that we end up where we started.
1184 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1185 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1186 Node *u = n->last_out(j); // Clone private computation per use
1187 _igvn.rehash_node_delayed(u);
1188 Node *x = n->clone(); // Clone computation
1189 Node *x_ctrl = NULL;
1190 if( u->is_Phi() ) {
1191 // Replace all uses of normal nodes. Replace Phi uses
1192 // individually, so the separate Nodes can sink down
1193 // different paths.
1194 uint k = 1;
1195 while( u->in(k) != n ) k++;
1196 u->set_req( k, x );
1197 // x goes next to Phi input path
1198 x_ctrl = u->in(0)->in(k);
1199 --j;
1200 } else { // Normal use
1201 // Replace all uses
1202 for( uint k = 0; k < u->req(); k++ ) {
1203 if( u->in(k) == n ) {
1204 u->set_req( k, x );
1205 --j;
1206 }
1207 }
1208 x_ctrl = get_ctrl(u);
1209 }
1210
1211 // Find control for 'x' next to use but not inside inner loops.
1212 // For inner loop uses get the preheader area.
1213 x_ctrl = place_near_use(x_ctrl);
1214
1215 if (n->is_Load()) {
1216 // For loads, add a control edge to a CFG node outside of the loop
1217 // to force them to not combine and return back inside the loop
1218 // during GVN optimization (4641526).
1219 //
1220 // Because we are setting the actual control input, factor in
1221 // the result from get_late_ctrl() so we respect any
1222 // anti-dependences. (6233005).
1223 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1224
1225 // Don't allow the control input to be a CFG splitting node.
1226 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1227 // should only have IfTrueNode and IfFalseNode (4985384).
1228 x_ctrl = find_non_split_ctrl(x_ctrl);
1229 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1230
1231 x->set_req(0, x_ctrl);
1232 }
1233 register_new_node(x, x_ctrl);
1234
1235 // Some institutional knowledge is needed here: 'x' is
1236 // yanked because if the optimizer runs GVN on it all the
1237 // cloned x's will common up and undo this optimization and
1238 // be forced back in the loop. This is annoying because it
1239 // makes +VerifyOpto report false-positives on progress. I
1240 // tried setting control edges on the x's to force them to
1241 // not combine, but the matching gets worried when it tries
1242 // to fold a StoreP and an AddP together (as part of an
1243 // address expression) and the AddP and StoreP have
1244 // different controls.
1245 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1246 }
1247 _igvn.remove_dead_node(n);
1248 }
1249 }
1250 }
1251 }
1252
1253 try_move_store_after_loop(n);
1254
1255 // Check for Opaque2's who's loop has disappeared - who's input is in the
1256 // same loop nest as their output. Remove 'em, they are no longer useful.
1257 if( n_op == Op_Opaque2 &&
1258 n->in(1) != NULL &&
1259 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1260 _igvn.replace_node( n, n->in(1) );
1261 }
1262 }
1263
1264 //------------------------------split_if_with_blocks---------------------------
1265 // Check for aggressive application of 'split-if' optimization,
1266 // using basic block level info.
1267 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1268 Node *n = C->root();
1269 visited.set(n->_idx); // first, mark node as visited
1270 // Do pre-visit work for root
1271 n = split_if_with_blocks_pre( n );
1272 uint cnt = n->outcnt();
1273 uint i = 0;
1274 while (true) {
1275 // Visit all children
1276 if (i < cnt) {
1277 Node* use = n->raw_out(i);
1278 ++i;
1279 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1280 // Now do pre-visit work for this use
1281 use = split_if_with_blocks_pre( use );
1282 nstack.push(n, i); // Save parent and next use's index.
1283 n = use; // Process all children of current use.
1284 cnt = use->outcnt();
1285 i = 0;
1286 }
1287 }
1288 else {
1289 // All of n's children have been processed, complete post-processing.
1290 if (cnt != 0 && !n->is_Con()) {
1291 assert(has_node(n), "no dead nodes");
1292 split_if_with_blocks_post( n );
1293 }
1294 if (nstack.is_empty()) {
1295 // Finished all nodes on stack.
1296 break;
1297 }
1298 // Get saved parent node and next use's index. Visit the rest of uses.
1299 n = nstack.node();
1300 cnt = n->outcnt();
1301 i = nstack.index();
1302 nstack.pop();
1303 }
1304 }
1305 }
1306
1307
1308 //=============================================================================
1309 //
1310 // C L O N E A L O O P B O D Y
1311 //
1312
1313 //------------------------------clone_iff--------------------------------------
1314 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1315 // "Nearly" because all Nodes have been cloned from the original in the loop,
1316 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1317 // through the Phi recursively, and return a Bool.
1318 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1319
1320 // Convert this Phi into a Phi merging Bools
1321 uint i;
1322 for( i = 1; i < phi->req(); i++ ) {
1323 Node *b = phi->in(i);
1324 if( b->is_Phi() ) {
1325 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1326 } else {
1327 assert( b->is_Bool(), "" );
1328 }
1329 }
1330
1331 Node *sample_bool = phi->in(1);
1332 Node *sample_cmp = sample_bool->in(1);
1333
1334 // Make Phis to merge the Cmp's inputs.
1335 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1336 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1337 for( i = 1; i < phi->req(); i++ ) {
1338 Node *n1 = phi->in(i)->in(1)->in(1);
1339 Node *n2 = phi->in(i)->in(1)->in(2);
1340 phi1->set_req( i, n1 );
1341 phi2->set_req( i, n2 );
1342 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1343 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1344 }
1345 // See if these Phis have been made before.
1346 // Register with optimizer
1347 Node *hit1 = _igvn.hash_find_insert(phi1);
1348 if( hit1 ) { // Hit, toss just made Phi
1349 _igvn.remove_dead_node(phi1); // Remove new phi
1350 assert( hit1->is_Phi(), "" );
1351 phi1 = (PhiNode*)hit1; // Use existing phi
1352 } else { // Miss
1353 _igvn.register_new_node_with_optimizer(phi1);
1354 }
1355 Node *hit2 = _igvn.hash_find_insert(phi2);
1356 if( hit2 ) { // Hit, toss just made Phi
1357 _igvn.remove_dead_node(phi2); // Remove new phi
1358 assert( hit2->is_Phi(), "" );
1359 phi2 = (PhiNode*)hit2; // Use existing phi
1360 } else { // Miss
1361 _igvn.register_new_node_with_optimizer(phi2);
1362 }
1363 // Register Phis with loop/block info
1364 set_ctrl(phi1, phi->in(0));
1365 set_ctrl(phi2, phi->in(0));
1366 // Make a new Cmp
1367 Node *cmp = sample_cmp->clone();
1368 cmp->set_req( 1, phi1 );
1369 cmp->set_req( 2, phi2 );
1370 _igvn.register_new_node_with_optimizer(cmp);
1371 set_ctrl(cmp, phi->in(0));
1372
1373 // Make a new Bool
1374 Node *b = sample_bool->clone();
1375 b->set_req(1,cmp);
1376 _igvn.register_new_node_with_optimizer(b);
1377 set_ctrl(b, phi->in(0));
1378
1379 assert( b->is_Bool(), "" );
1380 return (BoolNode*)b;
1381 }
1382
1383 //------------------------------clone_bool-------------------------------------
1384 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1385 // "Nearly" because all Nodes have been cloned from the original in the loop,
1386 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1387 // through the Phi recursively, and return a Bool.
1388 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1389 uint i;
1390 // Convert this Phi into a Phi merging Bools
1391 for( i = 1; i < phi->req(); i++ ) {
1392 Node *b = phi->in(i);
1393 if( b->is_Phi() ) {
1394 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1395 } else {
1396 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1397 }
1398 }
1399
1400 Node *sample_cmp = phi->in(1);
1401
1402 // Make Phis to merge the Cmp's inputs.
1403 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1404 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1405 for( uint j = 1; j < phi->req(); j++ ) {
1406 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1407 Node *n1, *n2;
1408 if( cmp_top->is_Cmp() ) {
1409 n1 = cmp_top->in(1);
1410 n2 = cmp_top->in(2);
1411 } else {
1412 n1 = n2 = cmp_top;
1413 }
1414 phi1->set_req( j, n1 );
1415 phi2->set_req( j, n2 );
1416 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1417 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1418 }
1419
1420 // See if these Phis have been made before.
1421 // Register with optimizer
1422 Node *hit1 = _igvn.hash_find_insert(phi1);
1423 if( hit1 ) { // Hit, toss just made Phi
1424 _igvn.remove_dead_node(phi1); // Remove new phi
1425 assert( hit1->is_Phi(), "" );
1426 phi1 = (PhiNode*)hit1; // Use existing phi
1427 } else { // Miss
1428 _igvn.register_new_node_with_optimizer(phi1);
1429 }
1430 Node *hit2 = _igvn.hash_find_insert(phi2);
1431 if( hit2 ) { // Hit, toss just made Phi
1432 _igvn.remove_dead_node(phi2); // Remove new phi
1433 assert( hit2->is_Phi(), "" );
1434 phi2 = (PhiNode*)hit2; // Use existing phi
1435 } else { // Miss
1436 _igvn.register_new_node_with_optimizer(phi2);
1437 }
1438 // Register Phis with loop/block info
1439 set_ctrl(phi1, phi->in(0));
1440 set_ctrl(phi2, phi->in(0));
1441 // Make a new Cmp
1442 Node *cmp = sample_cmp->clone();
1443 cmp->set_req( 1, phi1 );
1444 cmp->set_req( 2, phi2 );
1445 _igvn.register_new_node_with_optimizer(cmp);
1446 set_ctrl(cmp, phi->in(0));
1447
1448 assert( cmp->is_Cmp(), "" );
1449 return (CmpNode*)cmp;
1450 }
1451
1452 //------------------------------sink_use---------------------------------------
1453 // If 'use' was in the loop-exit block, it now needs to be sunk
1454 // below the post-loop merge point.
1455 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1456 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1457 set_ctrl(use, post_loop);
1458 for (DUIterator j = use->outs(); use->has_out(j); j++)
1459 sink_use(use->out(j), post_loop);
1460 }
1461 }
1462
1463 //------------------------------clone_loop-------------------------------------
1464 //
1465 // C L O N E A L O O P B O D Y
1466 //
1467 // This is the basic building block of the loop optimizations. It clones an
1468 // entire loop body. It makes an old_new loop body mapping; with this mapping
1469 // you can find the new-loop equivalent to an old-loop node. All new-loop
1470 // nodes are exactly equal to their old-loop counterparts, all edges are the
1471 // same. All exits from the old-loop now have a RegionNode that merges the
1472 // equivalent new-loop path. This is true even for the normal "loop-exit"
1473 // condition. All uses of loop-invariant old-loop values now come from (one
1474 // or more) Phis that merge their new-loop equivalents.
1475 //
1476 // This operation leaves the graph in an illegal state: there are two valid
1477 // control edges coming from the loop pre-header to both loop bodies. I'll
1478 // definitely have to hack the graph after running this transform.
1479 //
1480 // From this building block I will further edit edges to perform loop peeling
1481 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1482 //
1483 // Parameter side_by_size_idom:
1484 // When side_by_size_idom is NULL, the dominator tree is constructed for
1485 // the clone loop to dominate the original. Used in construction of
1486 // pre-main-post loop sequence.
1487 // When nonnull, the clone and original are side-by-side, both are
1488 // dominated by the side_by_side_idom node. Used in construction of
1489 // unswitched loops.
1490 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1491 Node* side_by_side_idom) {
1492
1493 #ifndef PRODUCT
1494 if (C->do_vector_loop() && PrintOpto) {
1495 const char* mname = C->method()->name()->as_quoted_ascii();
1496 if (mname != NULL) {
1497 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1498 }
1499 }
1500 #endif
1501
1502 CloneMap& cm = C->clone_map();
1503 Dict* dict = cm.dict();
1504 if (C->do_vector_loop()) {
1505 cm.set_clone_idx(cm.max_gen()+1);
1506 #ifndef PRODUCT
1507 if (PrintOpto) {
1508 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1509 loop->dump_head();
1510 }
1511 #endif
1512 }
1513
1514 // Step 1: Clone the loop body. Make the old->new mapping.
1515 uint i;
1516 for( i = 0; i < loop->_body.size(); i++ ) {
1517 Node *old = loop->_body.at(i);
1518 Node *nnn = old->clone();
1519 old_new.map( old->_idx, nnn );
1520 if (C->do_vector_loop()) {
1521 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1522 }
1523 _igvn.register_new_node_with_optimizer(nnn);
1524 }
1525
1526
1527 // Step 2: Fix the edges in the new body. If the old input is outside the
1528 // loop use it. If the old input is INside the loop, use the corresponding
1529 // new node instead.
1530 for( i = 0; i < loop->_body.size(); i++ ) {
1531 Node *old = loop->_body.at(i);
1532 Node *nnn = old_new[old->_idx];
1533 // Fix CFG/Loop controlling the new node
1534 if (has_ctrl(old)) {
1535 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1536 } else {
1537 set_loop(nnn, loop->_parent);
1538 if (old->outcnt() > 0) {
1539 set_idom( nnn, old_new[idom(old)->_idx], dd );
1540 }
1541 }
1542 // Correct edges to the new node
1543 for( uint j = 0; j < nnn->req(); j++ ) {
1544 Node *n = nnn->in(j);
1545 if( n ) {
1546 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1547 if( loop->is_member( old_in_loop ) )
1548 nnn->set_req(j, old_new[n->_idx]);
1549 }
1550 }
1551 _igvn.hash_find_insert(nnn);
1552 }
1553 Node *newhead = old_new[loop->_head->_idx];
1554 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1555
1556
1557 // Step 3: Now fix control uses. Loop varying control uses have already
1558 // been fixed up (as part of all input edges in Step 2). Loop invariant
1559 // control uses must be either an IfFalse or an IfTrue. Make a merge
1560 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1561 // refer to this.
1562 ResourceArea *area = Thread::current()->resource_area();
1563 Node_List worklist(area);
1564 uint new_counter = C->unique();
1565 for( i = 0; i < loop->_body.size(); i++ ) {
1566 Node* old = loop->_body.at(i);
1567 if( !old->is_CFG() ) continue;
1568 Node* nnn = old_new[old->_idx];
1569
1570 // Copy uses to a worklist, so I can munge the def-use info
1571 // with impunity.
1572 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1573 worklist.push(old->fast_out(j));
1574
1575 while( worklist.size() ) { // Visit all uses
1576 Node *use = worklist.pop();
1577 if (!has_node(use)) continue; // Ignore dead nodes
1578 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1579 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1580 // Both OLD and USE are CFG nodes here.
1581 assert( use->is_Proj(), "" );
1582
1583 // Clone the loop exit control projection
1584 Node *newuse = use->clone();
1585 if (C->do_vector_loop()) {
1586 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1587 }
1588 newuse->set_req(0,nnn);
1589 _igvn.register_new_node_with_optimizer(newuse);
1590 set_loop(newuse, use_loop);
1591 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1592
1593 // We need a Region to merge the exit from the peeled body and the
1594 // exit from the old loop body.
1595 RegionNode *r = new RegionNode(3);
1596 // Map the old use to the new merge point
1597 old_new.map( use->_idx, r );
1598 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1599 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1600
1601 // The original user of 'use' uses 'r' instead.
1602 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1603 Node* useuse = use->last_out(l);
1604 _igvn.rehash_node_delayed(useuse);
1605 uint uses_found = 0;
1606 if( useuse->in(0) == use ) {
1607 useuse->set_req(0, r);
1608 uses_found++;
1609 if( useuse->is_CFG() ) {
1610 assert( dom_depth(useuse) > dd_r, "" );
1611 set_idom(useuse, r, dom_depth(useuse));
1612 }
1613 }
1614 for( uint k = 1; k < useuse->req(); k++ ) {
1615 if( useuse->in(k) == use ) {
1616 useuse->set_req(k, r);
1617 uses_found++;
1618 }
1619 }
1620 l -= uses_found; // we deleted 1 or more copies of this edge
1621 }
1622
1623 // Now finish up 'r'
1624 r->set_req( 1, newuse );
1625 r->set_req( 2, use );
1626 _igvn.register_new_node_with_optimizer(r);
1627 set_loop(r, use_loop);
1628 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1629 } // End of if a loop-exit test
1630 }
1631 }
1632
1633 // Step 4: If loop-invariant use is not control, it must be dominated by a
1634 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1635 // there if needed. Make a Phi there merging old and new used values.
1636 Node_List *split_if_set = NULL;
1637 Node_List *split_bool_set = NULL;
1638 Node_List *split_cex_set = NULL;
1639 for( i = 0; i < loop->_body.size(); i++ ) {
1640 Node* old = loop->_body.at(i);
1641 Node* nnn = old_new[old->_idx];
1642 // Copy uses to a worklist, so I can munge the def-use info
1643 // with impunity.
1644 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1645 worklist.push(old->fast_out(j));
1646
1647 while( worklist.size() ) {
1648 Node *use = worklist.pop();
1649 if (!has_node(use)) continue; // Ignore dead nodes
1650 if (use->in(0) == C->top()) continue;
1651 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1652 // Check for data-use outside of loop - at least one of OLD or USE
1653 // must not be a CFG node.
1654 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1655
1656 // If the Data use is an IF, that means we have an IF outside of the
1657 // loop that is switching on a condition that is set inside of the
1658 // loop. Happens if people set a loop-exit flag; then test the flag
1659 // in the loop to break the loop, then test is again outside of the
1660 // loop to determine which way the loop exited.
1661 // Loop predicate If node connects to Bool node through Opaque1 node.
1662 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1663 // Since this code is highly unlikely, we lazily build the worklist
1664 // of such Nodes to go split.
1665 if( !split_if_set )
1666 split_if_set = new Node_List(area);
1667 split_if_set->push(use);
1668 }
1669 if( use->is_Bool() ) {
1670 if( !split_bool_set )
1671 split_bool_set = new Node_List(area);
1672 split_bool_set->push(use);
1673 }
1674 if( use->Opcode() == Op_CreateEx ) {
1675 if( !split_cex_set )
1676 split_cex_set = new Node_List(area);
1677 split_cex_set->push(use);
1678 }
1679
1680
1681 // Get "block" use is in
1682 uint idx = 0;
1683 while( use->in(idx) != old ) idx++;
1684 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1685 assert( !loop->is_member( get_loop( prev ) ), "" );
1686 Node *cfg = prev->_idx >= new_counter
1687 ? prev->in(2)
1688 : idom(prev);
1689 if( use->is_Phi() ) // Phi use is in prior block
1690 cfg = prev->in(idx); // NOT in block of Phi itself
1691 if (cfg->is_top()) { // Use is dead?
1692 _igvn.replace_input_of(use, idx, C->top());
1693 continue;
1694 }
1695
1696 while( !loop->is_member( get_loop( cfg ) ) ) {
1697 prev = cfg;
1698 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1699 }
1700 // If the use occurs after merging several exits from the loop, then
1701 // old value must have dominated all those exits. Since the same old
1702 // value was used on all those exits we did not need a Phi at this
1703 // merge point. NOW we do need a Phi here. Each loop exit value
1704 // is now merged with the peeled body exit; each exit gets its own
1705 // private Phi and those Phis need to be merged here.
1706 Node *phi;
1707 if( prev->is_Region() ) {
1708 if( idx == 0 ) { // Updating control edge?
1709 phi = prev; // Just use existing control
1710 } else { // Else need a new Phi
1711 phi = PhiNode::make( prev, old );
1712 // Now recursively fix up the new uses of old!
1713 for( uint i = 1; i < prev->req(); i++ ) {
1714 worklist.push(phi); // Onto worklist once for each 'old' input
1715 }
1716 }
1717 } else {
1718 // Get new RegionNode merging old and new loop exits
1719 prev = old_new[prev->_idx];
1720 assert( prev, "just made this in step 7" );
1721 if( idx == 0 ) { // Updating control edge?
1722 phi = prev; // Just use existing control
1723 } else { // Else need a new Phi
1724 // Make a new Phi merging data values properly
1725 phi = PhiNode::make( prev, old );
1726 phi->set_req( 1, nnn );
1727 }
1728 }
1729 // If inserting a new Phi, check for prior hits
1730 if( idx != 0 ) {
1731 Node *hit = _igvn.hash_find_insert(phi);
1732 if( hit == NULL ) {
1733 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1734 } else { // or
1735 // Remove the new phi from the graph and use the hit
1736 _igvn.remove_dead_node(phi);
1737 phi = hit; // Use existing phi
1738 }
1739 set_ctrl(phi, prev);
1740 }
1741 // Make 'use' use the Phi instead of the old loop body exit value
1742 _igvn.replace_input_of(use, idx, phi);
1743 if( use->_idx >= new_counter ) { // If updating new phis
1744 // Not needed for correctness, but prevents a weak assert
1745 // in AddPNode from tripping (when we end up with different
1746 // base & derived Phis that will become the same after
1747 // IGVN does CSE).
1748 Node *hit = _igvn.hash_find_insert(use);
1749 if( hit ) // Go ahead and re-hash for hits.
1750 _igvn.replace_node( use, hit );
1751 }
1752
1753 // If 'use' was in the loop-exit block, it now needs to be sunk
1754 // below the post-loop merge point.
1755 sink_use( use, prev );
1756 }
1757 }
1758 }
1759
1760 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1761 // the loop uses a condition set in the loop. The original IF probably
1762 // takes control from one or more OLD Regions (which in turn get from NEW
1763 // Regions). In any case, there will be a set of Phis for each merge point
1764 // from the IF up to where the original BOOL def exists the loop.
1765 if( split_if_set ) {
1766 while( split_if_set->size() ) {
1767 Node *iff = split_if_set->pop();
1768 if( iff->in(1)->is_Phi() ) {
1769 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1770 _igvn.replace_input_of(iff, 1, b);
1771 }
1772 }
1773 }
1774 if( split_bool_set ) {
1775 while( split_bool_set->size() ) {
1776 Node *b = split_bool_set->pop();
1777 Node *phi = b->in(1);
1778 assert( phi->is_Phi(), "" );
1779 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1780 _igvn.replace_input_of(b, 1, cmp);
1781 }
1782 }
1783 if( split_cex_set ) {
1784 while( split_cex_set->size() ) {
1785 Node *b = split_cex_set->pop();
1786 assert( b->in(0)->is_Region(), "" );
1787 assert( b->in(1)->is_Phi(), "" );
1788 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1789 split_up( b, b->in(0), NULL );
1790 }
1791 }
1792
1793 }
1794
1795
1796 //---------------------- stride_of_possible_iv -------------------------------------
1797 // Looks for an iff/bool/comp with one operand of the compare
1798 // being a cycle involving an add and a phi,
1799 // with an optional truncation (left-shift followed by a right-shift)
1800 // of the add. Returns zero if not an iv.
1801 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1802 Node* trunc1 = NULL;
1803 Node* trunc2 = NULL;
1804 const TypeInt* ttype = NULL;
1805 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1806 return 0;
1807 }
1808 BoolNode* bl = iff->in(1)->as_Bool();
1809 Node* cmp = bl->in(1);
1810 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1811 return 0;
1812 }
1813 // Must have an invariant operand
1814 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1815 return 0;
1816 }
1817 Node* add2 = NULL;
1818 Node* cmp1 = cmp->in(1);
1819 if (cmp1->is_Phi()) {
1820 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1821 Node* phi = cmp1;
1822 for (uint i = 1; i < phi->req(); i++) {
1823 Node* in = phi->in(i);
1824 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1825 &trunc1, &trunc2, &ttype);
1826 if (add && add->in(1) == phi) {
1827 add2 = add->in(2);
1828 break;
1829 }
1830 }
1831 } else {
1832 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1833 Node* addtrunc = cmp1;
1834 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1835 &trunc1, &trunc2, &ttype);
1836 if (add && add->in(1)->is_Phi()) {
1837 Node* phi = add->in(1);
1838 for (uint i = 1; i < phi->req(); i++) {
1839 if (phi->in(i) == addtrunc) {
1840 add2 = add->in(2);
1841 break;
1842 }
1843 }
1844 }
1845 }
1846 if (add2 != NULL) {
1847 const TypeInt* add2t = _igvn.type(add2)->is_int();
1848 if (add2t->is_con()) {
1849 return add2t->get_con();
1850 }
1851 }
1852 return 0;
1853 }
1854
1855
1856 //---------------------- stay_in_loop -------------------------------------
1857 // Return the (unique) control output node that's in the loop (if it exists.)
1858 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1859 Node* unique = NULL;
1860 if (!n) return NULL;
1861 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1862 Node* use = n->fast_out(i);
1863 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1864 if (unique != NULL) {
1865 return NULL;
1866 }
1867 unique = use;
1868 }
1869 }
1870 return unique;
1871 }
1872
1873 //------------------------------ register_node -------------------------------------
1874 // Utility to register node "n" with PhaseIdealLoop
1875 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1876 _igvn.register_new_node_with_optimizer(n);
1877 loop->_body.push(n);
1878 if (n->is_CFG()) {
1879 set_loop(n, loop);
1880 set_idom(n, pred, ddepth);
1881 } else {
1882 set_ctrl(n, pred);
1883 }
1884 }
1885
1886 //------------------------------ proj_clone -------------------------------------
1887 // Utility to create an if-projection
1888 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1889 ProjNode* c = p->clone()->as_Proj();
1890 c->set_req(0, iff);
1891 return c;
1892 }
1893
1894 //------------------------------ short_circuit_if -------------------------------------
1895 // Force the iff control output to be the live_proj
1896 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1897 guarantee(live_proj != NULL, "null projection");
1898 int proj_con = live_proj->_con;
1899 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1900 Node *con = _igvn.intcon(proj_con);
1901 set_ctrl(con, C->root());
1902 if (iff) {
1903 iff->set_req(1, con);
1904 }
1905 return con;
1906 }
1907
1908 //------------------------------ insert_if_before_proj -------------------------------------
1909 // Insert a new if before an if projection (* - new node)
1910 //
1911 // before
1912 // if(test)
1913 // / \
1914 // v v
1915 // other-proj proj (arg)
1916 //
1917 // after
1918 // if(test)
1919 // / \
1920 // / v
1921 // | * proj-clone
1922 // v |
1923 // other-proj v
1924 // * new_if(relop(cmp[IU](left,right)))
1925 // / \
1926 // v v
1927 // * new-proj proj
1928 // (returned)
1929 //
1930 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1931 IfNode* iff = proj->in(0)->as_If();
1932 IdealLoopTree *loop = get_loop(proj);
1933 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1934 int ddepth = dom_depth(proj);
1935
1936 _igvn.rehash_node_delayed(iff);
1937 _igvn.rehash_node_delayed(proj);
1938
1939 proj->set_req(0, NULL); // temporary disconnect
1940 ProjNode* proj2 = proj_clone(proj, iff);
1941 register_node(proj2, loop, iff, ddepth);
1942
1943 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1944 register_node(cmp, loop, proj2, ddepth);
1945
1946 BoolNode* bol = new BoolNode(cmp, relop);
1947 register_node(bol, loop, proj2, ddepth);
1948
1949 int opcode = iff->Opcode();
1950 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
1951 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
1952 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
1953 register_node(new_if, loop, proj2, ddepth);
1954
1955 proj->set_req(0, new_if); // reattach
1956 set_idom(proj, new_if, ddepth);
1957
1958 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1959 guarantee(new_exit != NULL, "null exit node");
1960 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1961
1962 return new_exit;
1963 }
1964
1965 //------------------------------ insert_region_before_proj -------------------------------------
1966 // Insert a region before an if projection (* - new node)
1967 //
1968 // before
1969 // if(test)
1970 // / |
1971 // v |
1972 // proj v
1973 // other-proj
1974 //
1975 // after
1976 // if(test)
1977 // / |
1978 // v |
1979 // * proj-clone v
1980 // | other-proj
1981 // v
1982 // * new-region
1983 // |
1984 // v
1985 // * dum_if
1986 // / \
1987 // v \
1988 // * dum-proj v
1989 // proj
1990 //
1991 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1992 IfNode* iff = proj->in(0)->as_If();
1993 IdealLoopTree *loop = get_loop(proj);
1994 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1995 int ddepth = dom_depth(proj);
1996
1997 _igvn.rehash_node_delayed(iff);
1998 _igvn.rehash_node_delayed(proj);
1999
2000 proj->set_req(0, NULL); // temporary disconnect
2001 ProjNode* proj2 = proj_clone(proj, iff);
2002 register_node(proj2, loop, iff, ddepth);
2003
2004 RegionNode* reg = new RegionNode(2);
2005 reg->set_req(1, proj2);
2006 register_node(reg, loop, iff, ddepth);
2007
2008 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2009 register_node(dum_if, loop, reg, ddepth);
2010
2011 proj->set_req(0, dum_if); // reattach
2012 set_idom(proj, dum_if, ddepth);
2013
2014 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2015 register_node(dum_proj, loop, dum_if, ddepth);
2016
2017 return reg;
2018 }
2019
2020 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2021 // Clone a signed compare loop exit from an unsigned compare and
2022 // insert it before the unsigned cmp on the stay-in-loop path.
2023 // All new nodes inserted in the dominator tree between the original
2024 // if and it's projections. The original if test is replaced with
2025 // a constant to force the stay-in-loop path.
2026 //
2027 // This is done to make sure that the original if and it's projections
2028 // still dominate the same set of control nodes, that the ctrl() relation
2029 // from data nodes to them is preserved, and that their loop nesting is
2030 // preserved.
2031 //
2032 // before
2033 // if(i <u limit) unsigned compare loop exit
2034 // / |
2035 // v v
2036 // exit-proj stay-in-loop-proj
2037 //
2038 // after
2039 // if(stay-in-loop-const) original if
2040 // / |
2041 // / v
2042 // / if(i < limit) new signed test
2043 // / / |
2044 // / / v
2045 // / / if(i <u limit) new cloned unsigned test
2046 // / / / |
2047 // v v v |
2048 // region |
2049 // | |
2050 // dum-if |
2051 // / | |
2052 // ether | |
2053 // v v
2054 // exit-proj stay-in-loop-proj
2055 //
2056 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2057 const bool Signed = true;
2058 const bool Unsigned = false;
2059
2060 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2061 if (bol->_test._test != BoolTest::lt) return NULL;
2062 CmpNode* cmpu = bol->in(1)->as_Cmp();
2063 if (cmpu->Opcode() != Op_CmpU) return NULL;
2064 int stride = stride_of_possible_iv(if_cmpu);
2065 if (stride == 0) return NULL;
2066
2067 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2068 guarantee(lp_proj != NULL, "null loop node");
2069
2070 ProjNode* lp_continue = lp_proj->as_Proj();
2071 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2072
2073 Node* limit = NULL;
2074 if (stride > 0) {
2075 limit = cmpu->in(2);
2076 } else {
2077 limit = _igvn.makecon(TypeInt::ZERO);
2078 set_ctrl(limit, C->root());
2079 }
2080 // Create a new region on the exit path
2081 RegionNode* reg = insert_region_before_proj(lp_exit);
2082 guarantee(reg != NULL, "null region node");
2083
2084 // Clone the if-cmpu-true-false using a signed compare
2085 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2086 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2087 reg->add_req(cmpi_exit);
2088
2089 // Clone the if-cmpu-true-false
2090 BoolTest::mask rel_u = bol->_test._test;
2091 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2092 reg->add_req(cmpu_exit);
2093
2094 // Force original if to stay in loop.
2095 short_circuit_if(if_cmpu, lp_continue);
2096
2097 return cmpi_exit->in(0)->as_If();
2098 }
2099
2100 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2101 // Remove a previously inserted signed compare loop exit.
2102 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2103 Node* lp_proj = stay_in_loop(if_cmp, loop);
2104 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2105 stay_in_loop(lp_proj, loop)->is_If() &&
2106 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2107 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2108 set_ctrl(con, C->root());
2109 if_cmp->set_req(1, con);
2110 }
2111
2112 //------------------------------ scheduled_nodelist -------------------------------------
2113 // Create a post order schedule of nodes that are in the
2114 // "member" set. The list is returned in "sched".
2115 // The first node in "sched" is the loop head, followed by
2116 // nodes which have no inputs in the "member" set, and then
2117 // followed by the nodes that have an immediate input dependence
2118 // on a node in "sched".
2119 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2120
2121 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2122 Arena *a = Thread::current()->resource_area();
2123 VectorSet visited(a);
2124 Node_Stack nstack(a, loop->_body.size());
2125
2126 Node* n = loop->_head; // top of stack is cached in "n"
2127 uint idx = 0;
2128 visited.set(n->_idx);
2129
2130 // Initially push all with no inputs from within member set
2131 for(uint i = 0; i < loop->_body.size(); i++ ) {
2132 Node *elt = loop->_body.at(i);
2133 if (member.test(elt->_idx)) {
2134 bool found = false;
2135 for (uint j = 0; j < elt->req(); j++) {
2136 Node* def = elt->in(j);
2137 if (def && member.test(def->_idx) && def != elt) {
2138 found = true;
2139 break;
2140 }
2141 }
2142 if (!found && elt != loop->_head) {
2143 nstack.push(n, idx);
2144 n = elt;
2145 assert(!visited.test(n->_idx), "not seen yet");
2146 visited.set(n->_idx);
2147 }
2148 }
2149 }
2150
2151 // traverse out's that are in the member set
2152 while (true) {
2153 if (idx < n->outcnt()) {
2154 Node* use = n->raw_out(idx);
2155 idx++;
2156 if (!visited.test_set(use->_idx)) {
2157 if (member.test(use->_idx)) {
2158 nstack.push(n, idx);
2159 n = use;
2160 idx = 0;
2161 }
2162 }
2163 } else {
2164 // All outputs processed
2165 sched.push(n);
2166 if (nstack.is_empty()) break;
2167 n = nstack.node();
2168 idx = nstack.index();
2169 nstack.pop();
2170 }
2171 }
2172 }
2173
2174
2175 //------------------------------ has_use_in_set -------------------------------------
2176 // Has a use in the vector set
2177 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2178 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2179 Node* use = n->fast_out(j);
2180 if (vset.test(use->_idx)) {
2181 return true;
2182 }
2183 }
2184 return false;
2185 }
2186
2187
2188 //------------------------------ has_use_internal_to_set -------------------------------------
2189 // Has use internal to the vector set (ie. not in a phi at the loop head)
2190 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2191 Node* head = loop->_head;
2192 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2193 Node* use = n->fast_out(j);
2194 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2195 return true;
2196 }
2197 }
2198 return false;
2199 }
2200
2201
2202 //------------------------------ clone_for_use_outside_loop -------------------------------------
2203 // clone "n" for uses that are outside of loop
2204 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2205 int cloned = 0;
2206 assert(worklist.size() == 0, "should be empty");
2207 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2208 Node* use = n->fast_out(j);
2209 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2210 worklist.push(use);
2211 }
2212 }
2213 while( worklist.size() ) {
2214 Node *use = worklist.pop();
2215 if (!has_node(use) || use->in(0) == C->top()) continue;
2216 uint j;
2217 for (j = 0; j < use->req(); j++) {
2218 if (use->in(j) == n) break;
2219 }
2220 assert(j < use->req(), "must be there");
2221
2222 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2223 Node* n_clone = n->clone();
2224 _igvn.replace_input_of(use, j, n_clone);
2225 cloned++;
2226 Node* use_c;
2227 if (!use->is_Phi()) {
2228 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2229 } else {
2230 // Use in a phi is considered a use in the associated predecessor block
2231 use_c = use->in(0)->in(j);
2232 }
2233 set_ctrl(n_clone, use_c);
2234 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2235 get_loop(use_c)->_body.push(n_clone);
2236 _igvn.register_new_node_with_optimizer(n_clone);
2237 #if !defined(PRODUCT)
2238 if (TracePartialPeeling) {
2239 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2240 }
2241 #endif
2242 }
2243 return cloned;
2244 }
2245
2246
2247 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2248 // clone "n" for special uses that are in the not_peeled region.
2249 // If these def-uses occur in separate blocks, the code generator
2250 // marks the method as not compilable. For example, if a "BoolNode"
2251 // is in a different basic block than the "IfNode" that uses it, then
2252 // the compilation is aborted in the code generator.
2253 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2254 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2255 if (n->is_Phi() || n->is_Load()) {
2256 return;
2257 }
2258 assert(worklist.size() == 0, "should be empty");
2259 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2260 Node* use = n->fast_out(j);
2261 if ( not_peel.test(use->_idx) &&
2262 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2263 use->in(1) == n) {
2264 worklist.push(use);
2265 }
2266 }
2267 if (worklist.size() > 0) {
2268 // clone "n" and insert it between inputs of "n" and the use
2269 Node* n_clone = n->clone();
2270 loop->_body.push(n_clone);
2271 _igvn.register_new_node_with_optimizer(n_clone);
2272 set_ctrl(n_clone, get_ctrl(n));
2273 sink_list.push(n_clone);
2274 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2275 #if !defined(PRODUCT)
2276 if (TracePartialPeeling) {
2277 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2278 }
2279 #endif
2280 while( worklist.size() ) {
2281 Node *use = worklist.pop();
2282 _igvn.rehash_node_delayed(use);
2283 for (uint j = 1; j < use->req(); j++) {
2284 if (use->in(j) == n) {
2285 use->set_req(j, n_clone);
2286 }
2287 }
2288 }
2289 }
2290 }
2291
2292
2293 //------------------------------ insert_phi_for_loop -------------------------------------
2294 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2295 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2296 Node *phi = PhiNode::make(lp, back_edge_val);
2297 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2298 // Use existing phi if it already exists
2299 Node *hit = _igvn.hash_find_insert(phi);
2300 if( hit == NULL ) {
2301 _igvn.register_new_node_with_optimizer(phi);
2302 set_ctrl(phi, lp);
2303 } else {
2304 // Remove the new phi from the graph and use the hit
2305 _igvn.remove_dead_node(phi);
2306 phi = hit;
2307 }
2308 _igvn.replace_input_of(use, idx, phi);
2309 }
2310
2311 #ifdef ASSERT
2312 //------------------------------ is_valid_loop_partition -------------------------------------
2313 // Validate the loop partition sets: peel and not_peel
2314 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2315 VectorSet& not_peel ) {
2316 uint i;
2317 // Check that peel_list entries are in the peel set
2318 for (i = 0; i < peel_list.size(); i++) {
2319 if (!peel.test(peel_list.at(i)->_idx)) {
2320 return false;
2321 }
2322 }
2323 // Check at loop members are in one of peel set or not_peel set
2324 for (i = 0; i < loop->_body.size(); i++ ) {
2325 Node *def = loop->_body.at(i);
2326 uint di = def->_idx;
2327 // Check that peel set elements are in peel_list
2328 if (peel.test(di)) {
2329 if (not_peel.test(di)) {
2330 return false;
2331 }
2332 // Must be in peel_list also
2333 bool found = false;
2334 for (uint j = 0; j < peel_list.size(); j++) {
2335 if (peel_list.at(j)->_idx == di) {
2336 found = true;
2337 break;
2338 }
2339 }
2340 if (!found) {
2341 return false;
2342 }
2343 } else if (not_peel.test(di)) {
2344 if (peel.test(di)) {
2345 return false;
2346 }
2347 } else {
2348 return false;
2349 }
2350 }
2351 return true;
2352 }
2353
2354 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2355 // Ensure a use outside of loop is of the right form
2356 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2357 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2358 return (use->is_Phi() &&
2359 use_c->is_Region() && use_c->req() == 3 &&
2360 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2361 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2362 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2363 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2364 }
2365
2366 //------------------------------ is_valid_clone_loop_form -------------------------------------
2367 // Ensure that all uses outside of loop are of the right form
2368 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2369 uint orig_exit_idx, uint clone_exit_idx) {
2370 uint len = peel_list.size();
2371 for (uint i = 0; i < len; i++) {
2372 Node *def = peel_list.at(i);
2373
2374 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2375 Node *use = def->fast_out(j);
2376 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2377 if (!loop->is_member(get_loop(use_c))) {
2378 // use is not in the loop, check for correct structure
2379 if (use->in(0) == def) {
2380 // Okay
2381 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2382 return false;
2383 }
2384 }
2385 }
2386 }
2387 return true;
2388 }
2389 #endif
2390
2391 //------------------------------ partial_peel -------------------------------------
2392 // Partially peel (aka loop rotation) the top portion of a loop (called
2393 // the peel section below) by cloning it and placing one copy just before
2394 // the new loop head and the other copy at the bottom of the new loop.
2395 //
2396 // before after where it came from
2397 //
2398 // stmt1 stmt1
2399 // loop: stmt2 clone
2400 // stmt2 if condA goto exitA clone
2401 // if condA goto exitA new_loop: new
2402 // stmt3 stmt3 clone
2403 // if !condB goto loop if condB goto exitB clone
2404 // exitB: stmt2 orig
2405 // stmt4 if !condA goto new_loop orig
2406 // exitA: goto exitA
2407 // exitB:
2408 // stmt4
2409 // exitA:
2410 //
2411 // Step 1: find the cut point: an exit test on probable
2412 // induction variable.
2413 // Step 2: schedule (with cloning) operations in the peel
2414 // section that can be executed after the cut into
2415 // the section that is not peeled. This may need
2416 // to clone operations into exit blocks. For
2417 // instance, a reference to A[i] in the not-peel
2418 // section and a reference to B[i] in an exit block
2419 // may cause a left-shift of i by 2 to be placed
2420 // in the peel block. This step will clone the left
2421 // shift into the exit block and sink the left shift
2422 // from the peel to the not-peel section.
2423 // Step 3: clone the loop, retarget the control, and insert
2424 // phis for values that are live across the new loop
2425 // head. This is very dependent on the graph structure
2426 // from clone_loop. It creates region nodes for
2427 // exit control and associated phi nodes for values
2428 // flow out of the loop through that exit. The region
2429 // node is dominated by the clone's control projection.
2430 // So the clone's peel section is placed before the
2431 // new loop head, and the clone's not-peel section is
2432 // forms the top part of the new loop. The original
2433 // peel section forms the tail of the new loop.
2434 // Step 4: update the dominator tree and recompute the
2435 // dominator depth.
2436 //
2437 // orig
2438 //
2439 // stmt1
2440 // |
2441 // v
2442 // loop predicate
2443 // |
2444 // v
2445 // loop<----+
2446 // | |
2447 // stmt2 |
2448 // | |
2449 // v |
2450 // ifA |
2451 // / | |
2452 // v v |
2453 // false true ^ <-- last_peel
2454 // / | |
2455 // / ===|==cut |
2456 // / stmt3 | <-- first_not_peel
2457 // / | |
2458 // | v |
2459 // v ifB |
2460 // exitA: / \ |
2461 // / \ |
2462 // v v |
2463 // false true |
2464 // / \ |
2465 // / ----+
2466 // |
2467 // v
2468 // exitB:
2469 // stmt4
2470 //
2471 //
2472 // after clone loop
2473 //
2474 // stmt1
2475 // |
2476 // v
2477 // loop predicate
2478 // / \
2479 // clone / \ orig
2480 // / \
2481 // / \
2482 // v v
2483 // +---->loop loop<----+
2484 // | | | |
2485 // | stmt2 stmt2 |
2486 // | | | |
2487 // | v v |
2488 // | ifA ifA |
2489 // | | \ / | |
2490 // | v v v v |
2491 // ^ true false false true ^ <-- last_peel
2492 // | | ^ \ / | |
2493 // | cut==|== \ \ / ===|==cut |
2494 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2495 // | | dom | | | |
2496 // | v \ 1v v2 v |
2497 // | ifB regionA ifB |
2498 // | / \ | / \ |
2499 // | / \ v / \ |
2500 // | v v exitA: v v |
2501 // | true false false true |
2502 // | / ^ \ / \ |
2503 // +---- \ \ / ----+
2504 // dom \ /
2505 // \ 1v v2
2506 // regionB
2507 // |
2508 // v
2509 // exitB:
2510 // stmt4
2511 //
2512 //
2513 // after partial peel
2514 //
2515 // stmt1
2516 // |
2517 // v
2518 // loop predicate
2519 // /
2520 // clone / orig
2521 // / TOP
2522 // / \
2523 // v v
2524 // TOP->loop loop----+
2525 // | | |
2526 // stmt2 stmt2 |
2527 // | | |
2528 // v v |
2529 // ifA ifA |
2530 // | \ / | |
2531 // v v v v |
2532 // true false false true | <-- last_peel
2533 // | ^ \ / +------|---+
2534 // +->newloop \ \ / === ==cut | |
2535 // | stmt3 \ \ / TOP | |
2536 // | | dom | | stmt3 | | <-- first_not_peel
2537 // | v \ 1v v2 v | |
2538 // | ifB regionA ifB ^ v
2539 // | / \ | / \ | |
2540 // | / \ v / \ | |
2541 // | v v exitA: v v | |
2542 // | true false false true | |
2543 // | / ^ \ / \ | |
2544 // | | \ \ / v | |
2545 // | | dom \ / TOP | |
2546 // | | \ 1v v2 | |
2547 // ^ v regionB | |
2548 // | | | | |
2549 // | | v ^ v
2550 // | | exitB: | |
2551 // | | stmt4 | |
2552 // | +------------>-----------------+ |
2553 // | |
2554 // +-----------------<---------------------+
2555 //
2556 //
2557 // final graph
2558 //
2559 // stmt1
2560 // |
2561 // v
2562 // loop predicate
2563 // |
2564 // v
2565 // stmt2 clone
2566 // |
2567 // v
2568 // ........> ifA clone
2569 // : / |
2570 // dom / |
2571 // : v v
2572 // : false true
2573 // : | |
2574 // : | v
2575 // : | newloop<-----+
2576 // : | | |
2577 // : | stmt3 clone |
2578 // : | | |
2579 // : | v |
2580 // : | ifB |
2581 // : | / \ |
2582 // : | v v |
2583 // : | false true |
2584 // : | | | |
2585 // : | v stmt2 |
2586 // : | exitB: | |
2587 // : | stmt4 v |
2588 // : | ifA orig |
2589 // : | / \ |
2590 // : | / \ |
2591 // : | v v |
2592 // : | false true |
2593 // : | / \ |
2594 // : v v -----+
2595 // RegionA
2596 // |
2597 // v
2598 // exitA
2599 //
2600 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2601
2602 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2603 if (!loop->_head->is_Loop()) {
2604 return false; }
2605
2606 LoopNode *head = loop->_head->as_Loop();
2607
2608 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2609 return false;
2610 }
2611
2612 // Check for complex exit control
2613 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2614 Node *n = loop->_body.at(ii);
2615 int opc = n->Opcode();
2616 if (n->is_Call() ||
2617 opc == Op_Catch ||
2618 opc == Op_CatchProj ||
2619 opc == Op_Jump ||
2620 opc == Op_JumpProj) {
2621 #if !defined(PRODUCT)
2622 if (TracePartialPeeling) {
2623 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2624 }
2625 #endif
2626 return false;
2627 }
2628 }
2629
2630 int dd = dom_depth(head);
2631
2632 // Step 1: find cut point
2633
2634 // Walk up dominators to loop head looking for first loop exit
2635 // which is executed on every path thru loop.
2636 IfNode *peel_if = NULL;
2637 IfNode *peel_if_cmpu = NULL;
2638
2639 Node *iff = loop->tail();
2640 while( iff != head ) {
2641 if( iff->is_If() ) {
2642 Node *ctrl = get_ctrl(iff->in(1));
2643 if (ctrl->is_top()) return false; // Dead test on live IF.
2644 // If loop-varying exit-test, check for induction variable
2645 if( loop->is_member(get_loop(ctrl)) &&
2646 loop->is_loop_exit(iff) &&
2647 is_possible_iv_test(iff)) {
2648 Node* cmp = iff->in(1)->in(1);
2649 if (cmp->Opcode() == Op_CmpI) {
2650 peel_if = iff->as_If();
2651 } else {
2652 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2653 peel_if_cmpu = iff->as_If();
2654 }
2655 }
2656 }
2657 iff = idom(iff);
2658 }
2659 // Prefer signed compare over unsigned compare.
2660 IfNode* new_peel_if = NULL;
2661 if (peel_if == NULL) {
2662 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2663 return false; // No peel point found
2664 }
2665 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2666 if (new_peel_if == NULL) {
2667 return false; // No peel point found
2668 }
2669 peel_if = new_peel_if;
2670 }
2671 Node* last_peel = stay_in_loop(peel_if, loop);
2672 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2673 if (first_not_peeled == NULL || first_not_peeled == head) {
2674 return false;
2675 }
2676
2677 #if !defined(PRODUCT)
2678 if (TraceLoopOpts) {
2679 tty->print("PartialPeel ");
2680 loop->dump_head();
2681 }
2682
2683 if (TracePartialPeeling) {
2684 tty->print_cr("before partial peel one iteration");
2685 Node_List wl;
2686 Node* t = head->in(2);
2687 while (true) {
2688 wl.push(t);
2689 if (t == head) break;
2690 t = idom(t);
2691 }
2692 while (wl.size() > 0) {
2693 Node* tt = wl.pop();
2694 tt->dump();
2695 if (tt == last_peel) tty->print_cr("-- cut --");
2696 }
2697 }
2698 #endif
2699 ResourceArea *area = Thread::current()->resource_area();
2700 VectorSet peel(area);
2701 VectorSet not_peel(area);
2702 Node_List peel_list(area);
2703 Node_List worklist(area);
2704 Node_List sink_list(area);
2705
2706 // Set of cfg nodes to peel are those that are executable from
2707 // the head through last_peel.
2708 assert(worklist.size() == 0, "should be empty");
2709 worklist.push(head);
2710 peel.set(head->_idx);
2711 while (worklist.size() > 0) {
2712 Node *n = worklist.pop();
2713 if (n != last_peel) {
2714 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2715 Node* use = n->fast_out(j);
2716 if (use->is_CFG() &&
2717 loop->is_member(get_loop(use)) &&
2718 !peel.test_set(use->_idx)) {
2719 worklist.push(use);
2720 }
2721 }
2722 }
2723 }
2724
2725 // Set of non-cfg nodes to peel are those that are control
2726 // dependent on the cfg nodes.
2727 uint i;
2728 for(i = 0; i < loop->_body.size(); i++ ) {
2729 Node *n = loop->_body.at(i);
2730 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2731 if (peel.test(n_c->_idx)) {
2732 peel.set(n->_idx);
2733 } else {
2734 not_peel.set(n->_idx);
2735 }
2736 }
2737
2738 // Step 2: move operations from the peeled section down into the
2739 // not-peeled section
2740
2741 // Get a post order schedule of nodes in the peel region
2742 // Result in right-most operand.
2743 scheduled_nodelist(loop, peel, peel_list );
2744
2745 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2746
2747 // For future check for too many new phis
2748 uint old_phi_cnt = 0;
2749 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2750 Node* use = head->fast_out(j);
2751 if (use->is_Phi()) old_phi_cnt++;
2752 }
2753
2754 #if !defined(PRODUCT)
2755 if (TracePartialPeeling) {
2756 tty->print_cr("\npeeled list");
2757 }
2758 #endif
2759
2760 // Evacuate nodes in peel region into the not_peeled region if possible
2761 uint new_phi_cnt = 0;
2762 uint cloned_for_outside_use = 0;
2763 for (i = 0; i < peel_list.size();) {
2764 Node* n = peel_list.at(i);
2765 #if !defined(PRODUCT)
2766 if (TracePartialPeeling) n->dump();
2767 #endif
2768 bool incr = true;
2769 if ( !n->is_CFG() ) {
2770
2771 if ( has_use_in_set(n, not_peel) ) {
2772
2773 // If not used internal to the peeled region,
2774 // move "n" from peeled to not_peeled region.
2775
2776 if ( !has_use_internal_to_set(n, peel, loop) ) {
2777
2778 // if not pinned and not a load (which maybe anti-dependent on a store)
2779 // and not a CMove (Matcher expects only bool->cmove).
2780 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2781 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2782 sink_list.push(n);
2783 peel >>= n->_idx; // delete n from peel set.
2784 not_peel <<= n->_idx; // add n to not_peel set.
2785 peel_list.remove(i);
2786 incr = false;
2787 #if !defined(PRODUCT)
2788 if (TracePartialPeeling) {
2789 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2790 n->_idx, get_ctrl(n)->_idx);
2791 }
2792 #endif
2793 }
2794 } else {
2795 // Otherwise check for special def-use cases that span
2796 // the peel/not_peel boundary such as bool->if
2797 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2798 new_phi_cnt++;
2799 }
2800 }
2801 }
2802 if (incr) i++;
2803 }
2804
2805 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2806 #if !defined(PRODUCT)
2807 if (TracePartialPeeling) {
2808 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2809 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2810 }
2811 #endif
2812 if (new_peel_if != NULL) {
2813 remove_cmpi_loop_exit(new_peel_if, loop);
2814 }
2815 // Inhibit more partial peeling on this loop
2816 assert(!head->is_partial_peel_loop(), "not partial peeled");
2817 head->mark_partial_peel_failed();
2818 if (cloned_for_outside_use > 0) {
2819 // Terminate this round of loop opts because
2820 // the graph outside this loop was changed.
2821 C->set_major_progress();
2822 return true;
2823 }
2824 return false;
2825 }
2826
2827 // Step 3: clone loop, retarget control, and insert new phis
2828
2829 // Create new loop head for new phis and to hang
2830 // the nodes being moved (sinked) from the peel region.
2831 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2832 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2833 _igvn.register_new_node_with_optimizer(new_head);
2834 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2835 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2836 set_loop(new_head, loop);
2837 loop->_body.push(new_head);
2838 not_peel.set(new_head->_idx);
2839 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2840 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2841
2842 while (sink_list.size() > 0) {
2843 Node* n = sink_list.pop();
2844 set_ctrl(n, new_head);
2845 }
2846
2847 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2848
2849 clone_loop( loop, old_new, dd );
2850
2851 const uint clone_exit_idx = 1;
2852 const uint orig_exit_idx = 2;
2853 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2854
2855 Node* head_clone = old_new[head->_idx];
2856 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2857 Node* orig_tail_clone = head_clone->in(2);
2858
2859 // Add phi if "def" node is in peel set and "use" is not
2860
2861 for(i = 0; i < peel_list.size(); i++ ) {
2862 Node *def = peel_list.at(i);
2863 if (!def->is_CFG()) {
2864 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2865 Node *use = def->fast_out(j);
2866 if (has_node(use) && use->in(0) != C->top() &&
2867 (!peel.test(use->_idx) ||
2868 (use->is_Phi() && use->in(0) == head)) ) {
2869 worklist.push(use);
2870 }
2871 }
2872 while( worklist.size() ) {
2873 Node *use = worklist.pop();
2874 for (uint j = 1; j < use->req(); j++) {
2875 Node* n = use->in(j);
2876 if (n == def) {
2877
2878 // "def" is in peel set, "use" is not in peel set
2879 // or "use" is in the entry boundary (a phi) of the peel set
2880
2881 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2882
2883 if ( loop->is_member(get_loop( use_c )) ) {
2884 // use is in loop
2885 if (old_new[use->_idx] != NULL) { // null for dead code
2886 Node* use_clone = old_new[use->_idx];
2887 _igvn.replace_input_of(use, j, C->top());
2888 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2889 }
2890 } else {
2891 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2892 // use is not in the loop, check if the live range includes the cut
2893 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2894 if (not_peel.test(lp_if->_idx)) {
2895 assert(j == orig_exit_idx, "use from original loop");
2896 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2897 }
2898 }
2899 }
2900 }
2901 }
2902 }
2903 }
2904
2905 // Step 3b: retarget control
2906
2907 // Redirect control to the new loop head if a cloned node in
2908 // the not_peeled region has control that points into the peeled region.
2909 // This necessary because the cloned peeled region will be outside
2910 // the loop.
2911 // from to
2912 // cloned-peeled <---+
2913 // new_head_clone: | <--+
2914 // cloned-not_peeled in(0) in(0)
2915 // orig-peeled
2916
2917 for(i = 0; i < loop->_body.size(); i++ ) {
2918 Node *n = loop->_body.at(i);
2919 if (!n->is_CFG() && n->in(0) != NULL &&
2920 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2921 Node* n_clone = old_new[n->_idx];
2922 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2923 }
2924 }
2925
2926 // Backedge of the surviving new_head (the clone) is original last_peel
2927 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2928
2929 // Cut first node in original not_peel set
2930 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2931 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2932 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2933
2934 // Copy head_clone back-branch info to original head
2935 // and remove original head's loop entry and
2936 // clone head's back-branch
2937 _igvn.rehash_node_delayed(head); // Multiple edge updates
2938 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2939 head->set_req(LoopNode::LoopBackControl, C->top());
2940 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2941
2942 // Similarly modify the phis
2943 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2944 Node* use = head->fast_out(k);
2945 if (use->is_Phi() && use->outcnt() > 0) {
2946 Node* use_clone = old_new[use->_idx];
2947 _igvn.rehash_node_delayed(use); // Multiple edge updates
2948 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2949 use->set_req(LoopNode::LoopBackControl, C->top());
2950 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2951 }
2952 }
2953
2954 // Step 4: update dominator tree and dominator depth
2955
2956 set_idom(head, orig_tail_clone, dd);
2957 recompute_dom_depth();
2958
2959 // Inhibit more partial peeling on this loop
2960 new_head_clone->set_partial_peel_loop();
2961 C->set_major_progress();
2962 loop->record_for_igvn();
2963
2964 #if !defined(PRODUCT)
2965 if (TracePartialPeeling) {
2966 tty->print_cr("\nafter partial peel one iteration");
2967 Node_List wl(area);
2968 Node* t = last_peel;
2969 while (true) {
2970 wl.push(t);
2971 if (t == head_clone) break;
2972 t = idom(t);
2973 }
2974 while (wl.size() > 0) {
2975 Node* tt = wl.pop();
2976 if (tt == head) tty->print_cr("orig head");
2977 else if (tt == new_head_clone) tty->print_cr("new head");
2978 else if (tt == head_clone) tty->print_cr("clone head");
2979 tt->dump();
2980 }
2981 }
2982 #endif
2983 return true;
2984 }
2985
2986 //------------------------------reorg_offsets----------------------------------
2987 // Reorganize offset computations to lower register pressure. Mostly
2988 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2989 // then alive with the post-incremented trip counter forcing an extra
2990 // register move)
2991 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2992 // Perform it only for canonical counted loops.
2993 // Loop's shape could be messed up by iteration_split_impl.
2994 if (!loop->_head->is_CountedLoop())
2995 return;
2996 if (!loop->_head->as_Loop()->is_valid_counted_loop())
2997 return;
2998
2999 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3000 CountedLoopEndNode *cle = cl->loopexit();
3001 Node *exit = cle->proj_out(false);
3002 Node *phi = cl->phi();
3003
3004 // Check for the special case of folks using the pre-incremented
3005 // trip-counter on the fall-out path (forces the pre-incremented
3006 // and post-incremented trip counter to be live at the same time).
3007 // Fix this by adjusting to use the post-increment trip counter.
3008
3009 bool progress = true;
3010 while (progress) {
3011 progress = false;
3012 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3013 Node* use = phi->fast_out(i); // User of trip-counter
3014 if (!has_ctrl(use)) continue;
3015 Node *u_ctrl = get_ctrl(use);
3016 if (use->is_Phi()) {
3017 u_ctrl = NULL;
3018 for (uint j = 1; j < use->req(); j++)
3019 if (use->in(j) == phi)
3020 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3021 }
3022 IdealLoopTree *u_loop = get_loop(u_ctrl);
3023 // Look for loop-invariant use
3024 if (u_loop == loop) continue;
3025 if (loop->is_member(u_loop)) continue;
3026 // Check that use is live out the bottom. Assuming the trip-counter
3027 // update is right at the bottom, uses of of the loop middle are ok.
3028 if (dom_lca(exit, u_ctrl) != exit) continue;
3029 // Hit! Refactor use to use the post-incremented tripcounter.
3030 // Compute a post-increment tripcounter.
3031 Node *opaq = new Opaque2Node( C, cle->incr() );
3032 register_new_node(opaq, exit);
3033 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3034 set_ctrl(neg_stride, C->root());
3035 Node *post = new AddINode( opaq, neg_stride);
3036 register_new_node(post, exit);
3037 _igvn.rehash_node_delayed(use);
3038 for (uint j = 1; j < use->req(); j++) {
3039 if (use->in(j) == phi)
3040 use->set_req(j, post);
3041 }
3042 // Since DU info changed, rerun loop
3043 progress = true;
3044 break;
3045 }
3046 }
3047
3048 }