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