1 /*
2 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/castnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/castnode.hpp"
31 #include "opto/divnode.hpp"
32 #include "opto/loopnode.hpp"
33 #include "opto/matcher.hpp"
34 #include "opto/mulnode.hpp"
35 #include "opto/movenode.hpp"
36 #include "opto/opaquenode.hpp"
37 #include "opto/rootnode.hpp"
38 #include "opto/subnode.hpp"
39
40 //=============================================================================
41 //------------------------------split_thru_phi---------------------------------
42 // Split Node 'n' through merge point if there is enough win.
43 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
44 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
45 // ConvI2L may have type information on it which is unsafe to push up
46 // so disable this for now
47 return NULL;
48 }
49
50 int wins = 0;
51 assert(!n->is_CFG(), "");
52 assert(region->is_Region(), "");
53
54 const Type* type = n->bottom_type();
55 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
56 Node *phi;
57 if (t_oop != NULL && t_oop->is_known_instance_field()) {
58 int iid = t_oop->instance_id();
59 int index = C->get_alias_index(t_oop);
60 int offset = t_oop->offset();
61 phi = new PhiNode(region, type, NULL, iid, index, offset);
62 } else {
63 phi = PhiNode::make_blank(region, n);
64 }
65 uint old_unique = C->unique();
66 for (uint i = 1; i < region->req(); i++) {
67 Node *x;
68 Node* the_clone = NULL;
69 if (region->in(i) == C->top()) {
70 x = C->top(); // Dead path? Use a dead data op
71 } else {
72 x = n->clone(); // Else clone up the data op
73 the_clone = x; // Remember for possible deletion.
74 // Alter data node to use pre-phi inputs
75 if (n->in(0) == region)
76 x->set_req( 0, region->in(i) );
77 for (uint j = 1; j < n->req(); j++) {
78 Node *in = n->in(j);
79 if (in->is_Phi() && in->in(0) == region)
80 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
81 }
82 }
83 // Check for a 'win' on some paths
84 const Type *t = x->Value(&_igvn);
85
86 bool singleton = t->singleton();
87
88 // A TOP singleton indicates that there are no possible values incoming
89 // along a particular edge. In most cases, this is OK, and the Phi will
90 // be eliminated later in an Ideal call. However, we can't allow this to
91 // happen if the singleton occurs on loop entry, as the elimination of
92 // the PhiNode may cause the resulting node to migrate back to a previous
93 // loop iteration.
94 if (singleton && t == Type::TOP) {
95 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
96 // irreducible loop may not be indicated by an affirmative is_Loop());
97 // therefore, the only top we can split thru a phi is on a backedge of
98 // a loop.
99 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
100 }
101
102 if (singleton) {
103 wins++;
104 x = ((PhaseGVN&)_igvn).makecon(t);
105 } else {
106 // We now call Identity to try to simplify the cloned node.
107 // Note that some Identity methods call phase->type(this).
108 // Make sure that the type array is big enough for
109 // our new node, even though we may throw the node away.
110 // (Note: This tweaking with igvn only works because x is a new node.)
111 _igvn.set_type(x, t);
112 // If x is a TypeNode, capture any more-precise type permanently into Node
113 // otherwise it will be not updated during igvn->transform since
114 // igvn->type(x) is set to x->Value() already.
115 x->raise_bottom_type(t);
116 Node *y = x->Identity(&_igvn);
117 if (y != x) {
118 wins++;
119 x = y;
120 } else {
121 y = _igvn.hash_find(x);
122 if (y) {
123 wins++;
124 x = y;
125 } else {
126 // Else x is a new node we are keeping
127 // We do not need register_new_node_with_optimizer
128 // because set_type has already been called.
129 _igvn._worklist.push(x);
130 }
131 }
132 }
133 if (x != the_clone && the_clone != NULL)
134 _igvn.remove_dead_node(the_clone);
135 phi->set_req( i, x );
136 }
137 // Too few wins?
138 if (wins <= policy) {
139 _igvn.remove_dead_node(phi);
140 return NULL;
141 }
142
143 // Record Phi
144 register_new_node( phi, region );
145
146 for (uint i2 = 1; i2 < phi->req(); i2++) {
147 Node *x = phi->in(i2);
148 // If we commoned up the cloned 'x' with another existing Node,
149 // the existing Node picks up a new use. We need to make the
150 // existing Node occur higher up so it dominates its uses.
151 Node *old_ctrl;
152 IdealLoopTree *old_loop;
153
154 if (x->is_Con()) {
155 // Constant's control is always root.
156 set_ctrl(x, C->root());
157 continue;
158 }
159 // The occasional new node
160 if (x->_idx >= old_unique) { // Found a new, unplaced node?
161 old_ctrl = NULL;
162 old_loop = NULL; // Not in any prior loop
163 } else {
164 old_ctrl = get_ctrl(x);
165 old_loop = get_loop(old_ctrl); // Get prior loop
166 }
167 // New late point must dominate new use
168 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
169 if (new_ctrl == old_ctrl) // Nothing is changed
170 continue;
171
172 IdealLoopTree *new_loop = get_loop(new_ctrl);
173
174 // Don't move x into a loop if its uses are
175 // outside of loop. Otherwise x will be cloned
176 // for each use outside of this loop.
177 IdealLoopTree *use_loop = get_loop(region);
178 if (!new_loop->is_member(use_loop) &&
179 (old_loop == NULL || !new_loop->is_member(old_loop))) {
180 // Take early control, later control will be recalculated
181 // during next iteration of loop optimizations.
182 new_ctrl = get_early_ctrl(x);
183 new_loop = get_loop(new_ctrl);
184 }
185 // Set new location
186 set_ctrl(x, new_ctrl);
187 // If changing loop bodies, see if we need to collect into new body
188 if (old_loop != new_loop) {
189 if (old_loop && !old_loop->_child)
190 old_loop->_body.yank(x);
191 if (!new_loop->_child)
192 new_loop->_body.push(x); // Collect body info
193 }
194 }
195
196 return phi;
197 }
198
199 //------------------------------dominated_by------------------------------------
200 // Replace the dominated test with an obvious true or false. Place it on the
201 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
202 // live path up to the dominating control.
203 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
204 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
205
206 // prevdom is the dominating projection of the dominating test.
207 assert( iff->is_If(), "" );
208 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
209 int pop = prevdom->Opcode();
210 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
211 if (flip) {
212 if (pop == Op_IfTrue)
213 pop = Op_IfFalse;
214 else
215 pop = Op_IfTrue;
216 }
217 // 'con' is set to true or false to kill the dominated test.
218 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
219 set_ctrl(con, C->root()); // Constant gets a new use
220 // Hack the dominated test
221 _igvn.replace_input_of(iff, 1, con);
222
223 // If I dont have a reachable TRUE and FALSE path following the IfNode then
224 // I can assume this path reaches an infinite loop. In this case it's not
225 // important to optimize the data Nodes - either the whole compilation will
226 // be tossed or this path (and all data Nodes) will go dead.
227 if (iff->outcnt() != 2) return;
228
229 // Make control-dependent data Nodes on the live path (path that will remain
230 // once the dominated IF is removed) become control-dependent on the
231 // dominating projection.
232 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
233
234 // Loop predicates may have depending checks which should not
235 // be skipped. For example, range check predicate has two checks
236 // for lower and upper bounds.
237 if (dp == NULL)
238 return;
239
240 ProjNode* dp_proj = dp->as_Proj();
241 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
242 if (exclude_loop_predicate &&
243 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
244 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
245 // If this is a range check (IfNode::is_range_check), do not
246 // reorder because Compile::allow_range_check_smearing might have
247 // changed the check.
248 return; // Let IGVN transformation change control dependence.
249 }
250
251 IdealLoopTree *old_loop = get_loop(dp);
252
253 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
254 Node* cd = dp->fast_out(i); // Control-dependent node
255 if (cd->depends_only_on_test()) {
256 assert(cd->in(0) == dp, "");
257 _igvn.replace_input_of(cd, 0, prevdom);
258 set_early_ctrl(cd);
259 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
260 if (old_loop != new_loop) {
261 if (!old_loop->_child) old_loop->_body.yank(cd);
262 if (!new_loop->_child) new_loop->_body.push(cd);
263 }
264 --i;
265 --imax;
266 }
267 }
268 }
269
270 //------------------------------has_local_phi_input----------------------------
271 // Return TRUE if 'n' has Phi inputs from its local block and no other
272 // block-local inputs (all non-local-phi inputs come from earlier blocks)
273 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
274 Node *n_ctrl = get_ctrl(n);
275 // See if some inputs come from a Phi in this block, or from before
276 // this block.
277 uint i;
278 for( i = 1; i < n->req(); i++ ) {
279 Node *phi = n->in(i);
280 if( phi->is_Phi() && phi->in(0) == n_ctrl )
281 break;
282 }
283 if( i >= n->req() )
284 return NULL; // No Phi inputs; nowhere to clone thru
285
286 // Check for inputs created between 'n' and the Phi input. These
287 // must split as well; they have already been given the chance
288 // (courtesy of a post-order visit) and since they did not we must
289 // recover the 'cost' of splitting them by being very profitable
290 // when splitting 'n'. Since this is unlikely we simply give up.
291 for( i = 1; i < n->req(); i++ ) {
292 Node *m = n->in(i);
293 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
294 // We allow the special case of AddP's with no local inputs.
295 // This allows us to split-up address expressions.
296 if (m->is_AddP() &&
297 get_ctrl(m->in(2)) != n_ctrl &&
298 get_ctrl(m->in(3)) != n_ctrl) {
299 // Move the AddP up to dominating point
300 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
301 continue;
302 }
303 return NULL;
304 }
305 }
306
307 return n_ctrl;
308 }
309
310 //------------------------------remix_address_expressions----------------------
311 // Rework addressing expressions to get the most loop-invariant stuff
312 // moved out. We'd like to do all associative operators, but it's especially
313 // important (common) to do address expressions.
314 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
315 if (!has_ctrl(n)) return NULL;
316 Node *n_ctrl = get_ctrl(n);
317 IdealLoopTree *n_loop = get_loop(n_ctrl);
318
319 // See if 'n' mixes loop-varying and loop-invariant inputs and
320 // itself is loop-varying.
321
322 // Only interested in binary ops (and AddP)
323 if( n->req() < 3 || n->req() > 4 ) return NULL;
324
325 Node *n1_ctrl = get_ctrl(n->in( 1));
326 Node *n2_ctrl = get_ctrl(n->in( 2));
327 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
328 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
329 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
330 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
331
332 // Does one of my inputs spin in a tighter loop than self?
333 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
334 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
335 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
336 return NULL; // Leave well enough alone
337
338 // Is at least one of my inputs loop-invariant?
339 if( n1_loop == n_loop &&
340 n2_loop == n_loop &&
341 n3_loop == n_loop )
342 return NULL; // No loop-invariant inputs
343
344
345 int n_op = n->Opcode();
346
347 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
348 if( n_op == Op_LShiftI ) {
349 // Scale is loop invariant
350 Node *scale = n->in(2);
351 Node *scale_ctrl = get_ctrl(scale);
352 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
353 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
354 return NULL;
355 const TypeInt *scale_t = scale->bottom_type()->isa_int();
356 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
357 return NULL; // Dont bother with byte/short masking
358 // Add must vary with loop (else shift would be loop-invariant)
359 Node *add = n->in(1);
360 Node *add_ctrl = get_ctrl(add);
361 IdealLoopTree *add_loop = get_loop(add_ctrl);
362 //assert( n_loop == add_loop, "" );
363 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
364
365 // Convert I-V into I+ (0-V); same for V-I
366 if( add->Opcode() == Op_SubI &&
367 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
368 Node *zero = _igvn.intcon(0);
369 set_ctrl(zero, C->root());
370 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
371 register_new_node( neg, get_ctrl(add->in(2) ) );
372 add = new AddINode( add->in(1), neg );
373 register_new_node( add, add_ctrl );
374 }
375 if( add->Opcode() != Op_AddI ) return NULL;
376 // See if one add input is loop invariant
377 Node *add_var = add->in(1);
378 Node *add_var_ctrl = get_ctrl(add_var);
379 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
380 Node *add_invar = add->in(2);
381 Node *add_invar_ctrl = get_ctrl(add_invar);
382 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
383 if( add_var_loop == n_loop ) {
384 } else if( add_invar_loop == n_loop ) {
385 // Swap to find the invariant part
386 add_invar = add_var;
387 add_invar_ctrl = add_var_ctrl;
388 add_invar_loop = add_var_loop;
389 add_var = add->in(2);
390 Node *add_var_ctrl = get_ctrl(add_var);
391 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
392 } else // Else neither input is loop invariant
393 return NULL;
394 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
395 return NULL; // No invariant part of the add?
396
397 // Yes! Reshape address expression!
398 Node *inv_scale = new LShiftINode( add_invar, scale );
399 Node *inv_scale_ctrl =
400 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
401 add_invar_ctrl : scale_ctrl;
402 register_new_node( inv_scale, inv_scale_ctrl );
403 Node *var_scale = new LShiftINode( add_var, scale );
404 register_new_node( var_scale, n_ctrl );
405 Node *var_add = new AddINode( var_scale, inv_scale );
406 register_new_node( var_add, n_ctrl );
407 _igvn.replace_node( n, var_add );
408 return var_add;
409 }
410
411 // Replace (I+V) with (V+I)
412 if( n_op == Op_AddI ||
413 n_op == Op_AddL ||
414 n_op == Op_AddF ||
415 n_op == Op_AddD ||
416 n_op == Op_MulI ||
417 n_op == Op_MulL ||
418 n_op == Op_MulF ||
419 n_op == Op_MulD ) {
420 if( n2_loop == n_loop ) {
421 assert( n1_loop != n_loop, "" );
422 n->swap_edges(1, 2);
423 }
424 }
425
426 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
427 // but not if I2 is a constant.
428 if( n_op == Op_AddP ) {
429 if( n2_loop == n_loop && n3_loop != n_loop ) {
430 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
431 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
432 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
433 IdealLoopTree *n22loop = get_loop( n22_ctrl );
434 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
435 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
436 n23_loop == n_loop ) {
437 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
438 // Stuff new AddP in the loop preheader
439 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
440 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
441 register_new_node( add2, n_ctrl );
442 _igvn.replace_node( n, add2 );
443 return add2;
444 }
445 }
446 }
447
448 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
449 if (n2_loop != n_loop && n3_loop == n_loop) {
450 if (n->in(3)->Opcode() == Op_AddX) {
451 Node *V = n->in(3)->in(1);
452 Node *I = n->in(3)->in(2);
453 if (is_member(n_loop,get_ctrl(V))) {
454 } else {
455 Node *tmp = V; V = I; I = tmp;
456 }
457 if (!is_member(n_loop,get_ctrl(I))) {
458 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
459 // Stuff new AddP in the loop preheader
460 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
461 Node *add2 = new AddPNode(n->in(1), add1, V);
462 register_new_node(add2, n_ctrl);
463 _igvn.replace_node(n, add2);
464 return add2;
465 }
466 }
467 }
468 }
469
470 return NULL;
471 }
472
473 //------------------------------conditional_move-------------------------------
474 // Attempt to replace a Phi with a conditional move. We have some pretty
475 // strict profitability requirements. All Phis at the merge point must
476 // be converted, so we can remove the control flow. We need to limit the
477 // number of c-moves to a small handful. All code that was in the side-arms
478 // of the CFG diamond is now speculatively executed. This code has to be
479 // "cheap enough". We are pretty much limited to CFG diamonds that merge
480 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
481 Node *PhaseIdealLoop::conditional_move( Node *region ) {
482
483 assert(region->is_Region(), "sanity check");
484 if (region->req() != 3) return NULL;
485
486 // Check for CFG diamond
487 Node *lp = region->in(1);
488 Node *rp = region->in(2);
489 if (!lp || !rp) return NULL;
490 Node *lp_c = lp->in(0);
491 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
492 IfNode *iff = lp_c->as_If();
493
494 // Check for ops pinned in an arm of the diamond.
495 // Can't remove the control flow in this case
496 if (lp->outcnt() > 1) return NULL;
497 if (rp->outcnt() > 1) return NULL;
498
499 IdealLoopTree* r_loop = get_loop(region);
500 assert(r_loop == get_loop(iff), "sanity");
501 // Always convert to CMOVE if all results are used only outside this loop.
502 bool used_inside_loop = (r_loop == _ltree_root);
503
504 // Check profitability
505 int cost = 0;
506 int phis = 0;
507 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
508 Node *out = region->fast_out(i);
509 if (!out->is_Phi()) continue; // Ignore other control edges, etc
510 phis++;
511 PhiNode* phi = out->as_Phi();
512 BasicType bt = phi->type()->basic_type();
513 switch (bt) {
514 case T_DOUBLE:
515 if (C->use_cmove()) {
516 continue; //TODO: maybe we want to add some cost
517 }
518 case T_FLOAT: {
519 cost += Matcher::float_cmove_cost(); // Could be very expensive
520 break;
521 }
522 case T_LONG: {
523 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
524 }
525 case T_INT: // These all CMOV fine
526 case T_ADDRESS: { // (RawPtr)
527 cost++;
528 break;
529 }
530 case T_NARROWOOP: // Fall through
531 case T_OBJECT: { // Base oops are OK, but not derived oops
532 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
533 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
534 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
535 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
536 // have a Phi for the base here that we convert to a CMOVE all is well
537 // and good. But if the base is dead, we'll not make a CMOVE. Later
538 // the allocator will have to produce a base by creating a CMOVE of the
539 // relevant bases. This puts the allocator in the business of
540 // manufacturing expensive instructions, generally a bad plan.
541 // Just Say No to Conditionally-Moved Derived Pointers.
542 if (tp && tp->offset() != 0)
543 return NULL;
544 cost++;
545 break;
546 }
547 default:
548 return NULL; // In particular, can't do memory or I/O
549 }
550 // Add in cost any speculative ops
551 for (uint j = 1; j < region->req(); j++) {
552 Node *proj = region->in(j);
553 Node *inp = phi->in(j);
554 if (get_ctrl(inp) == proj) { // Found local op
555 cost++;
556 // Check for a chain of dependent ops; these will all become
557 // speculative in a CMOV.
558 for (uint k = 1; k < inp->req(); k++)
559 if (get_ctrl(inp->in(k)) == proj)
560 cost += ConditionalMoveLimit; // Too much speculative goo
561 }
562 }
563 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
564 // This will likely Split-If, a higher-payoff operation.
565 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
566 Node* use = phi->fast_out(k);
567 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
568 cost += ConditionalMoveLimit;
569 // Is there a use inside the loop?
570 // Note: check only basic types since CMoveP is pinned.
571 if (!used_inside_loop && is_java_primitive(bt)) {
572 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
573 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
574 used_inside_loop = true;
575 }
576 }
577 }
578 }//for
579 Node* bol = iff->in(1);
580 assert(bol->Opcode() == Op_Bool, "");
581 int cmp_op = bol->in(1)->Opcode();
582 // It is expensive to generate flags from a float compare.
583 // Avoid duplicated float compare.
584 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
585
586 float infrequent_prob = PROB_UNLIKELY_MAG(3);
587 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
588 if (used_inside_loop) {
589 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
590
591 // BlockLayoutByFrequency optimization moves infrequent branch
592 // from hot path. No point in CMOV'ing in such case (110 is used
593 // instead of 100 to take into account not exactness of float value).
594 if (BlockLayoutByFrequency) {
595 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
596 }
597 }
598 // Check for highly predictable branch. No point in CMOV'ing if
599 // we are going to predict accurately all the time.
600 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
601 else if (iff->_prob < infrequent_prob ||
602 iff->_prob > (1.0f - infrequent_prob))
603 return NULL;
604
605 // --------------
606 // Now replace all Phis with CMOV's
607 Node *cmov_ctrl = iff->in(0);
608 uint flip = (lp->Opcode() == Op_IfTrue);
609 while (1) {
610 PhiNode* phi = NULL;
611 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
612 Node *out = region->fast_out(i);
613 if (out->is_Phi()) {
614 phi = out->as_Phi();
615 break;
616 }
617 }
618 if (phi == NULL) break;
619 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
620 // Move speculative ops
621 for (uint j = 1; j < region->req(); j++) {
622 Node *proj = region->in(j);
623 Node *inp = phi->in(j);
624 if (get_ctrl(inp) == proj) { // Found local op
625 #ifndef PRODUCT
626 if (PrintOpto && VerifyLoopOptimizations) {
627 tty->print(" speculate: ");
628 inp->dump();
629 }
630 #endif
631 set_ctrl(inp, cmov_ctrl);
632 }
633 }
634 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
635 register_new_node( cmov, cmov_ctrl );
636 _igvn.replace_node( phi, cmov );
637 #ifndef PRODUCT
638 if (TraceLoopOpts) {
639 tty->print("CMOV ");
640 r_loop->dump_head();
641 if (Verbose) {
642 bol->in(1)->dump(1);
643 cmov->dump(1);
644 }
645 }
646 if (VerifyLoopOptimizations) verify();
647 #endif
648 }
649
650 // The useless CFG diamond will fold up later; see the optimization in
651 // RegionNode::Ideal.
652 _igvn._worklist.push(region);
653
654 return iff->in(1);
655 }
656
657 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
658 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
659 Node* u = m->fast_out(i);
660 if (u->is_CFG()) {
661 if (u->Opcode() == Op_NeverBranch) {
662 u = ((NeverBranchNode*)u)->proj_out(0);
663 enqueue_cfg_uses(u, wq);
664 } else {
665 wq.push(u);
666 }
667 }
668 }
669 }
670
671 // Try moving a store out of a loop, right before the loop
672 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
673 // Store has to be first in the loop body
674 IdealLoopTree *n_loop = get_loop(n_ctrl);
675 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
676 Node* address = n->in(MemNode::Address);
677 Node* value = n->in(MemNode::ValueIn);
678 Node* mem = n->in(MemNode::Memory);
679 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
680 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
681
682 // - address and value must be loop invariant
683 // - memory must be a memory Phi for the loop
684 // - Store must be the only store on this memory slice in the
685 // loop: if there's another store following this one then value
686 // written at iteration i by the second store could be overwritten
687 // at iteration i+n by the first store: it's not safe to move the
688 // first store out of the loop
689 // - nothing must observe the memory Phi: it guarantees no read
690 // before the store, we are also guaranteed the store post
691 // dominates the loop head (ignoring a possible early
692 // exit). Otherwise there would be extra Phi involved between the
693 // loop's Phi and the store.
694 // - there must be no early exit from the loop before the Store
695 // (such an exit most of the time would be an extra use of the
696 // memory Phi but sometimes is a bottom memory Phi that takes the
697 // store as input).
698
699 if (!n_loop->is_member(address_loop) &&
700 !n_loop->is_member(value_loop) &&
701 mem->is_Phi() && mem->in(0) == n_loop->_head &&
702 mem->outcnt() == 1 &&
703 mem->in(LoopNode::LoopBackControl) == n) {
704
705 assert(n_loop->_tail != NULL, "need a tail");
706 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
707
708 // Verify that there's no early exit of the loop before the store.
709 bool ctrl_ok = false;
710 {
711 // Follow control from loop head until n, we exit the loop or
712 // we reach the tail
713 ResourceMark rm;
714 Unique_Node_List wq;
715 wq.push(n_loop->_head);
716
717 for (uint next = 0; next < wq.size(); ++next) {
718 Node *m = wq.at(next);
719 if (m == n->in(0)) {
720 ctrl_ok = true;
721 continue;
722 }
723 assert(!has_ctrl(m), "should be CFG");
724 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
725 ctrl_ok = false;
726 break;
727 }
728 enqueue_cfg_uses(m, wq);
729 if (wq.size() > 10) {
730 ctrl_ok = false;
731 break;
732 }
733 }
734 }
735 if (ctrl_ok) {
736 // move the Store
737 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
738 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
739 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
740 // Disconnect the phi now. An empty phi can confuse other
741 // optimizations in this pass of loop opts.
742 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
743 n_loop->_body.yank(mem);
744
745 IdealLoopTree* new_loop = get_loop(n->in(0));
746 set_ctrl_and_loop(n, n->in(0));
747
748 return n;
749 }
750 }
751 }
752 return NULL;
753 }
754
755 // Try moving a store out of a loop, right after the loop
756 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
757 if (n->is_Store() && n->in(0) != NULL) {
758 Node *n_ctrl = get_ctrl(n);
759 IdealLoopTree *n_loop = get_loop(n_ctrl);
760 // Store must be in a loop
761 if (n_loop != _ltree_root && !n_loop->_irreducible) {
762 Node* address = n->in(MemNode::Address);
763 Node* value = n->in(MemNode::ValueIn);
764 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
765 // address must be loop invariant
766 if (!n_loop->is_member(address_loop)) {
767 // Store must be last on this memory slice in the loop and
768 // nothing in the loop must observe it
769 Node* phi = NULL;
770 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
771 Node* u = n->fast_out(i);
772 if (has_ctrl(u)) { // control use?
773 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
774 if (!n_loop->is_member(u_loop)) {
775 continue;
776 }
777 if (u->is_Phi() && u->in(0) == n_loop->_head) {
778 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
779 // multiple phis on the same slice are possible
780 if (phi != NULL) {
781 return;
782 }
783 phi = u;
784 continue;
785 }
786 }
787 return;
788 }
789 if (phi != NULL) {
790 // Nothing in the loop before the store (next iteration)
791 // must observe the stored value
792 bool mem_ok = true;
793 {
794 ResourceMark rm;
795 Unique_Node_List wq;
796 wq.push(phi);
797 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
798 Node *m = wq.at(next);
799 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
800 Node* u = m->fast_out(i);
801 if (u->is_Store() || u->is_Phi()) {
802 if (u != n) {
803 wq.push(u);
804 mem_ok = (wq.size() <= 10);
805 }
806 } else {
807 mem_ok = false;
808 break;
809 }
810 }
811 }
812 }
813 if (mem_ok) {
814 // Move the Store out of the loop creating clones along
815 // all paths out of the loop that observe the stored value
816 _igvn.rehash_node_delayed(phi);
817 int count = phi->replace_edge(n, n->in(MemNode::Memory));
818 assert(count > 0, "inconsistent phi");
819 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
820 Node* u = n->fast_out(i);
821 Node* c = get_ctrl(u);
822
823 if (u->is_Phi()) {
824 c = u->in(0)->in(u->find_edge(n));
825 }
826 IdealLoopTree *u_loop = get_loop(c);
827 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
828 while(true) {
829 Node* next_c = find_non_split_ctrl(idom(c));
830 if (n_loop->is_member(get_loop(next_c))) {
831 break;
832 }
833 c = next_c;
834 }
835
836 Node* st = n->clone();
837 st->set_req(0, c);
838 _igvn.register_new_node_with_optimizer(st);
839
840 set_ctrl(st, c);
841 IdealLoopTree* new_loop = get_loop(c);
842 assert(new_loop != n_loop, "should be moved out of loop");
843 if (new_loop->_child == NULL) new_loop->_body.push(st);
844
845 _igvn.replace_input_of(u, u->find_edge(n), st);
846 --imax;
847 --i;
848 }
849
850
851 assert(n->outcnt() == 0, "all uses should be gone");
852 _igvn.replace_input_of(n, MemNode::Memory, C->top());
853 // Disconnect the phi now. An empty phi can confuse other
854 // optimizations in this pass of loop opts..
855 if (phi->in(LoopNode::LoopBackControl) == phi) {
856 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
857 n_loop->_body.yank(phi);
858 }
859 }
860 }
861 }
862 }
863 }
864 }
865
866 //------------------------------split_if_with_blocks_pre-----------------------
867 // Do the real work in a non-recursive function. Data nodes want to be
868 // cloned in the pre-order so they can feed each other nicely.
869 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
870 // Cloning these guys is unlikely to win
871 int n_op = n->Opcode();
872 if( n_op == Op_MergeMem ) return n;
873 if( n->is_Proj() ) return n;
874 // Do not clone-up CmpFXXX variations, as these are always
875 // followed by a CmpI
876 if( n->is_Cmp() ) return n;
877 // Attempt to use a conditional move instead of a phi/branch
878 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
879 Node *cmov = conditional_move( n );
880 if( cmov ) return cmov;
881 }
882 if( n->is_CFG() || n->is_LoadStore() )
883 return n;
884 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
885 n_op == Op_Opaque2 ) {
886 if( !C->major_progress() ) // If chance of no more loop opts...
887 _igvn._worklist.push(n); // maybe we'll remove them
888 return n;
889 }
890
891 if( n->is_Con() ) return n; // No cloning for Con nodes
892
893 Node *n_ctrl = get_ctrl(n);
894 if( !n_ctrl ) return n; // Dead node
895
896 Node* res = try_move_store_before_loop(n, n_ctrl);
897 if (res != NULL) {
898 return n;
899 }
900
901 // Attempt to remix address expressions for loop invariants
902 Node *m = remix_address_expressions( n );
903 if( m ) return m;
904
905 if (n->is_ConstraintCast()) {
906 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(this);
907 if (dom_cast != NULL) {
908 _igvn.replace_node(n, dom_cast);
909 return dom_cast;
910 }
911 }
912
913 // Determine if the Node has inputs from some local Phi.
914 // Returns the block to clone thru.
915 Node *n_blk = has_local_phi_input( n );
916 if( !n_blk ) return n;
917
918 // Do not clone the trip counter through on a CountedLoop
919 // (messes up the canonical shape).
920 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
921
922 // Check for having no control input; not pinned. Allow
923 // dominating control.
924 if (n->in(0)) {
925 Node *dom = idom(n_blk);
926 if (dom_lca(n->in(0), dom) != n->in(0)) {
927 return n;
928 }
929 }
930 // Policy: when is it profitable. You must get more wins than
931 // policy before it is considered profitable. Policy is usually 0,
932 // so 1 win is considered profitable. Big merges will require big
933 // cloning, so get a larger policy.
934 int policy = n_blk->req() >> 2;
935
936 // If the loop is a candidate for range check elimination,
937 // delay splitting through it's phi until a later loop optimization
938 if (n_blk->is_CountedLoop()) {
939 IdealLoopTree *lp = get_loop(n_blk);
940 if (lp && lp->_rce_candidate) {
941 return n;
942 }
943 }
944
945 // Use same limit as split_if_with_blocks_post
946 if( C->live_nodes() > 35000 ) return n; // Method too big
947
948 // Split 'n' through the merge point if it is profitable
949 Node *phi = split_thru_phi( n, n_blk, policy );
950 if (!phi) return n;
951
952 // Found a Phi to split thru!
953 // Replace 'n' with the new phi
954 _igvn.replace_node( n, phi );
955 // Moved a load around the loop, 'en-registering' something.
956 if (n_blk->is_Loop() && n->is_Load() &&
957 !phi->in(LoopNode::LoopBackControl)->is_Load())
958 C->set_major_progress();
959
960 return phi;
961 }
962
963 static bool merge_point_too_heavy(Compile* C, Node* region) {
964 // Bail out if the region and its phis have too many users.
965 int weight = 0;
966 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
967 weight += region->fast_out(i)->outcnt();
968 }
969 int nodes_left = C->max_node_limit() - C->live_nodes();
970 if (weight * 8 > nodes_left) {
971 if (PrintOpto) {
972 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
973 }
974 return true;
975 } else {
976 return false;
977 }
978 }
979
980 static bool merge_point_safe(Node* region) {
981 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
982 // having a PhiNode input. This sidesteps the dangerous case where the split
983 // ConvI2LNode may become TOP if the input Value() does not
984 // overlap the ConvI2L range, leaving a node which may not dominate its
985 // uses.
986 // A better fix for this problem can be found in the BugTraq entry, but
987 // expediency for Mantis demands this hack.
988 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
989 // split_if_with_blocks from splitting a block because we could not move around
990 // the FastLockNode.
991 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
992 Node* n = region->fast_out(i);
993 if (n->is_Phi()) {
994 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
995 Node* m = n->fast_out(j);
996 if (m->is_FastLock())
997 return false;
998 #ifdef _LP64
999 if (m->Opcode() == Op_ConvI2L)
1000 return false;
1001 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1002 return false;
1003 }
1004 #endif
1005 }
1006 }
1007 }
1008 return true;
1009 }
1010
1011
1012 //------------------------------place_near_use---------------------------------
1013 // Place some computation next to use but not inside inner loops.
1014 // For inner loop uses move it to the preheader area.
1015 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1016 IdealLoopTree *u_loop = get_loop( useblock );
1017 return (u_loop->_irreducible || u_loop->_child)
1018 ? useblock
1019 : u_loop->_head->in(LoopNode::EntryControl);
1020 }
1021
1022
1023 //------------------------------split_if_with_blocks_post----------------------
1024 // Do the real work in a non-recursive function. CFG hackery wants to be
1025 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1026 // info.
1027 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1028
1029 // Cloning Cmp through Phi's involves the split-if transform.
1030 // FastLock is not used by an If
1031 if( n->is_Cmp() && !n->is_FastLock() ) {
1032 if( C->live_nodes() > 35000 ) return; // Method too big
1033
1034 // Do not do 'split-if' if irreducible loops are present.
1035 if( _has_irreducible_loops )
1036 return;
1037
1038 Node *n_ctrl = get_ctrl(n);
1039 // Determine if the Node has inputs from some local Phi.
1040 // Returns the block to clone thru.
1041 Node *n_blk = has_local_phi_input( n );
1042 if( n_blk != n_ctrl ) return;
1043
1044 if( merge_point_too_heavy(C, n_ctrl) )
1045 return;
1046
1047 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1048 Node *bol = n->unique_out();
1049 assert( bol->is_Bool(), "expect a bool here" );
1050 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1051 Node *iff = bol->unique_out();
1052
1053 // Check some safety conditions
1054 if( iff->is_If() ) { // Classic split-if?
1055 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1056 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1057 // Can't split CMove with different control edge.
1058 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1059 if( get_ctrl(iff->in(2)) == n_ctrl ||
1060 get_ctrl(iff->in(3)) == n_ctrl )
1061 return; // Inputs not yet split-up
1062 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1063 return; // Loop-invar test gates loop-varying CMOVE
1064 }
1065 } else {
1066 return; // some other kind of node, such as an Allocate
1067 }
1068
1069 // Do not do 'split-if' if some paths are dead. First do dead code
1070 // elimination and then see if its still profitable.
1071 for( uint i = 1; i < n_ctrl->req(); i++ )
1072 if( n_ctrl->in(i) == C->top() )
1073 return;
1074
1075 // When is split-if profitable? Every 'win' on means some control flow
1076 // goes dead, so it's almost always a win.
1077 int policy = 0;
1078 // If trying to do a 'Split-If' at the loop head, it is only
1079 // profitable if the cmp folds up on BOTH paths. Otherwise we
1080 // risk peeling a loop forever.
1081
1082 // CNC - Disabled for now. Requires careful handling of loop
1083 // body selection for the cloned code. Also, make sure we check
1084 // for any input path not being in the same loop as n_ctrl. For
1085 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1086 // because the alternative loop entry points won't be converted
1087 // into LoopNodes.
1088 IdealLoopTree *n_loop = get_loop(n_ctrl);
1089 for( uint j = 1; j < n_ctrl->req(); j++ )
1090 if( get_loop(n_ctrl->in(j)) != n_loop )
1091 return;
1092
1093 // Check for safety of the merge point.
1094 if( !merge_point_safe(n_ctrl) ) {
1095 return;
1096 }
1097
1098 // Split compare 'n' through the merge point if it is profitable
1099 Node *phi = split_thru_phi( n, n_ctrl, policy );
1100 if( !phi ) return;
1101
1102 // Found a Phi to split thru!
1103 // Replace 'n' with the new phi
1104 _igvn.replace_node( n, phi );
1105
1106 // Now split the bool up thru the phi
1107 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1108 guarantee(bolphi != NULL, "null boolean phi node");
1109
1110 _igvn.replace_node( bol, bolphi );
1111 assert( iff->in(1) == bolphi, "" );
1112
1113 if( bolphi->Value(&_igvn)->singleton() )
1114 return;
1115
1116 // Conditional-move? Must split up now
1117 if( !iff->is_If() ) {
1118 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1119 _igvn.replace_node( iff, cmovphi );
1120 return;
1121 }
1122
1123 // Now split the IF
1124 do_split_if( iff );
1125 return;
1126 }
1127
1128 // Check for an IF ready to split; one that has its
1129 // condition codes input coming from a Phi at the block start.
1130 int n_op = n->Opcode();
1131
1132 // Check for an IF being dominated by another IF same test
1133 if (n_op == Op_If ||
1134 n_op == Op_RangeCheck) {
1135 Node *bol = n->in(1);
1136 uint max = bol->outcnt();
1137 // Check for same test used more than once?
1138 if (max > 1 && bol->is_Bool()) {
1139 // Search up IDOMs to see if this IF is dominated.
1140 Node *cutoff = get_ctrl(bol);
1141
1142 // Now search up IDOMs till cutoff, looking for a dominating test
1143 Node *prevdom = n;
1144 Node *dom = idom(prevdom);
1145 while (dom != cutoff) {
1146 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1147 // Replace the dominated test with an obvious true or false.
1148 // Place it on the IGVN worklist for later cleanup.
1149 C->set_major_progress();
1150 dominated_by(prevdom, n, false, true);
1151 #ifndef PRODUCT
1152 if( VerifyLoopOptimizations ) verify();
1153 #endif
1154 return;
1155 }
1156 prevdom = dom;
1157 dom = idom(prevdom);
1158 }
1159 }
1160 }
1161
1162 // See if a shared loop-varying computation has no loop-varying uses.
1163 // Happens if something is only used for JVM state in uncommon trap exits,
1164 // like various versions of induction variable+offset. Clone the
1165 // computation per usage to allow it to sink out of the loop.
1166 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1167 Node *n_ctrl = get_ctrl(n);
1168 IdealLoopTree *n_loop = get_loop(n_ctrl);
1169 if( n_loop != _ltree_root ) {
1170 DUIterator_Fast imax, i = n->fast_outs(imax);
1171 for (; i < imax; i++) {
1172 Node* u = n->fast_out(i);
1173 if( !has_ctrl(u) ) break; // Found control user
1174 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1175 if( u_loop == n_loop ) break; // Found loop-varying use
1176 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1177 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1178 }
1179 bool did_break = (i < imax); // Did we break out of the previous loop?
1180 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1181 Node *late_load_ctrl = NULL;
1182 if (n->is_Load()) {
1183 // If n is a load, get and save the result from get_late_ctrl(),
1184 // to be later used in calculating the control for n's clones.
1185 clear_dom_lca_tags();
1186 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1187 }
1188 // If n is a load, and the late control is the same as the current
1189 // control, then the cloning of n is a pointless exercise, because
1190 // GVN will ensure that we end up where we started.
1191 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1192 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1193 Node *u = n->last_out(j); // Clone private computation per use
1194 _igvn.rehash_node_delayed(u);
1195 Node *x = n->clone(); // Clone computation
1196 Node *x_ctrl = NULL;
1197 if( u->is_Phi() ) {
1198 // Replace all uses of normal nodes. Replace Phi uses
1199 // individually, so the separate Nodes can sink down
1200 // different paths.
1201 uint k = 1;
1202 while( u->in(k) != n ) k++;
1203 u->set_req( k, x );
1204 // x goes next to Phi input path
1205 x_ctrl = u->in(0)->in(k);
1206 --j;
1207 } else { // Normal use
1208 // Replace all uses
1209 for( uint k = 0; k < u->req(); k++ ) {
1210 if( u->in(k) == n ) {
1211 u->set_req( k, x );
1212 --j;
1213 }
1214 }
1215 x_ctrl = get_ctrl(u);
1216 }
1217
1218 // Find control for 'x' next to use but not inside inner loops.
1219 // For inner loop uses get the preheader area.
1220 x_ctrl = place_near_use(x_ctrl);
1221
1222 if (n->is_Load()) {
1223 // For loads, add a control edge to a CFG node outside of the loop
1224 // to force them to not combine and return back inside the loop
1225 // during GVN optimization (4641526).
1226 //
1227 // Because we are setting the actual control input, factor in
1228 // the result from get_late_ctrl() so we respect any
1229 // anti-dependences. (6233005).
1230 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1231
1232 // Don't allow the control input to be a CFG splitting node.
1233 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1234 // should only have IfTrueNode and IfFalseNode (4985384).
1235 x_ctrl = find_non_split_ctrl(x_ctrl);
1236 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1237
1238 x->set_req(0, x_ctrl);
1239 }
1240 register_new_node(x, x_ctrl);
1241
1242 // Some institutional knowledge is needed here: 'x' is
1243 // yanked because if the optimizer runs GVN on it all the
1244 // cloned x's will common up and undo this optimization and
1245 // be forced back in the loop. This is annoying because it
1246 // makes +VerifyOpto report false-positives on progress. I
1247 // tried setting control edges on the x's to force them to
1248 // not combine, but the matching gets worried when it tries
1249 // to fold a StoreP and an AddP together (as part of an
1250 // address expression) and the AddP and StoreP have
1251 // different controls.
1252 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1253 }
1254 _igvn.remove_dead_node(n);
1255 }
1256 }
1257 }
1258 }
1259
1260 try_move_store_after_loop(n);
1261
1262 // Check for Opaque2's who's loop has disappeared - who's input is in the
1263 // same loop nest as their output. Remove 'em, they are no longer useful.
1264 if( n_op == Op_Opaque2 &&
1265 n->in(1) != NULL &&
1266 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1267 _igvn.replace_node( n, n->in(1) );
1268 }
1269 }
1270
1271 //------------------------------split_if_with_blocks---------------------------
1272 // Check for aggressive application of 'split-if' optimization,
1273 // using basic block level info.
1274 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1275 Node *n = C->root();
1276 visited.set(n->_idx); // first, mark node as visited
1277 // Do pre-visit work for root
1278 n = split_if_with_blocks_pre( n );
1279 uint cnt = n->outcnt();
1280 uint i = 0;
1281 while (true) {
1282 // Visit all children
1283 if (i < cnt) {
1284 Node* use = n->raw_out(i);
1285 ++i;
1286 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1287 // Now do pre-visit work for this use
1288 use = split_if_with_blocks_pre( use );
1289 nstack.push(n, i); // Save parent and next use's index.
1290 n = use; // Process all children of current use.
1291 cnt = use->outcnt();
1292 i = 0;
1293 }
1294 }
1295 else {
1296 // All of n's children have been processed, complete post-processing.
1297 if (cnt != 0 && !n->is_Con()) {
1298 assert(has_node(n), "no dead nodes");
1299 split_if_with_blocks_post( n );
1300 }
1301 if (nstack.is_empty()) {
1302 // Finished all nodes on stack.
1303 break;
1304 }
1305 // Get saved parent node and next use's index. Visit the rest of uses.
1306 n = nstack.node();
1307 cnt = n->outcnt();
1308 i = nstack.index();
1309 nstack.pop();
1310 }
1311 }
1312 }
1313
1314
1315 //=============================================================================
1316 //
1317 // C L O N E A L O O P B O D Y
1318 //
1319
1320 //------------------------------clone_iff--------------------------------------
1321 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1322 // "Nearly" because all Nodes have been cloned from the original in the loop,
1323 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1324 // through the Phi recursively, and return a Bool.
1325 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1326
1327 // Convert this Phi into a Phi merging Bools
1328 uint i;
1329 for( i = 1; i < phi->req(); i++ ) {
1330 Node *b = phi->in(i);
1331 if( b->is_Phi() ) {
1332 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1333 } else {
1334 assert( b->is_Bool(), "" );
1335 }
1336 }
1337
1338 Node *sample_bool = phi->in(1);
1339 Node *sample_cmp = sample_bool->in(1);
1340
1341 // Make Phis to merge the Cmp's inputs.
1342 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1343 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1344 for( i = 1; i < phi->req(); i++ ) {
1345 Node *n1 = phi->in(i)->in(1)->in(1);
1346 Node *n2 = phi->in(i)->in(1)->in(2);
1347 phi1->set_req( i, n1 );
1348 phi2->set_req( i, n2 );
1349 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1350 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1351 }
1352 // See if these Phis have been made before.
1353 // Register with optimizer
1354 Node *hit1 = _igvn.hash_find_insert(phi1);
1355 if( hit1 ) { // Hit, toss just made Phi
1356 _igvn.remove_dead_node(phi1); // Remove new phi
1357 assert( hit1->is_Phi(), "" );
1358 phi1 = (PhiNode*)hit1; // Use existing phi
1359 } else { // Miss
1360 _igvn.register_new_node_with_optimizer(phi1);
1361 }
1362 Node *hit2 = _igvn.hash_find_insert(phi2);
1363 if( hit2 ) { // Hit, toss just made Phi
1364 _igvn.remove_dead_node(phi2); // Remove new phi
1365 assert( hit2->is_Phi(), "" );
1366 phi2 = (PhiNode*)hit2; // Use existing phi
1367 } else { // Miss
1368 _igvn.register_new_node_with_optimizer(phi2);
1369 }
1370 // Register Phis with loop/block info
1371 set_ctrl(phi1, phi->in(0));
1372 set_ctrl(phi2, phi->in(0));
1373 // Make a new Cmp
1374 Node *cmp = sample_cmp->clone();
1375 cmp->set_req( 1, phi1 );
1376 cmp->set_req( 2, phi2 );
1377 _igvn.register_new_node_with_optimizer(cmp);
1378 set_ctrl(cmp, phi->in(0));
1379
1380 // Make a new Bool
1381 Node *b = sample_bool->clone();
1382 b->set_req(1,cmp);
1383 _igvn.register_new_node_with_optimizer(b);
1384 set_ctrl(b, phi->in(0));
1385
1386 assert( b->is_Bool(), "" );
1387 return (BoolNode*)b;
1388 }
1389
1390 //------------------------------clone_bool-------------------------------------
1391 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1392 // "Nearly" because all Nodes have been cloned from the original in the loop,
1393 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1394 // through the Phi recursively, and return a Bool.
1395 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1396 uint i;
1397 // Convert this Phi into a Phi merging Bools
1398 for( i = 1; i < phi->req(); i++ ) {
1399 Node *b = phi->in(i);
1400 if( b->is_Phi() ) {
1401 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1402 } else {
1403 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1404 }
1405 }
1406
1407 Node *sample_cmp = phi->in(1);
1408
1409 // Make Phis to merge the Cmp's inputs.
1410 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1411 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1412 for( uint j = 1; j < phi->req(); j++ ) {
1413 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1414 Node *n1, *n2;
1415 if( cmp_top->is_Cmp() ) {
1416 n1 = cmp_top->in(1);
1417 n2 = cmp_top->in(2);
1418 } else {
1419 n1 = n2 = cmp_top;
1420 }
1421 phi1->set_req( j, n1 );
1422 phi2->set_req( j, n2 );
1423 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1424 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1425 }
1426
1427 // See if these Phis have been made before.
1428 // Register with optimizer
1429 Node *hit1 = _igvn.hash_find_insert(phi1);
1430 if( hit1 ) { // Hit, toss just made Phi
1431 _igvn.remove_dead_node(phi1); // Remove new phi
1432 assert( hit1->is_Phi(), "" );
1433 phi1 = (PhiNode*)hit1; // Use existing phi
1434 } else { // Miss
1435 _igvn.register_new_node_with_optimizer(phi1);
1436 }
1437 Node *hit2 = _igvn.hash_find_insert(phi2);
1438 if( hit2 ) { // Hit, toss just made Phi
1439 _igvn.remove_dead_node(phi2); // Remove new phi
1440 assert( hit2->is_Phi(), "" );
1441 phi2 = (PhiNode*)hit2; // Use existing phi
1442 } else { // Miss
1443 _igvn.register_new_node_with_optimizer(phi2);
1444 }
1445 // Register Phis with loop/block info
1446 set_ctrl(phi1, phi->in(0));
1447 set_ctrl(phi2, phi->in(0));
1448 // Make a new Cmp
1449 Node *cmp = sample_cmp->clone();
1450 cmp->set_req( 1, phi1 );
1451 cmp->set_req( 2, phi2 );
1452 _igvn.register_new_node_with_optimizer(cmp);
1453 set_ctrl(cmp, phi->in(0));
1454
1455 assert( cmp->is_Cmp(), "" );
1456 return (CmpNode*)cmp;
1457 }
1458
1459 //------------------------------sink_use---------------------------------------
1460 // If 'use' was in the loop-exit block, it now needs to be sunk
1461 // below the post-loop merge point.
1462 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1463 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1464 set_ctrl(use, post_loop);
1465 for (DUIterator j = use->outs(); use->has_out(j); j++)
1466 sink_use(use->out(j), post_loop);
1467 }
1468 }
1469
1470 //------------------------------clone_loop-------------------------------------
1471 //
1472 // C L O N E A L O O P B O D Y
1473 //
1474 // This is the basic building block of the loop optimizations. It clones an
1475 // entire loop body. It makes an old_new loop body mapping; with this mapping
1476 // you can find the new-loop equivalent to an old-loop node. All new-loop
1477 // nodes are exactly equal to their old-loop counterparts, all edges are the
1478 // same. All exits from the old-loop now have a RegionNode that merges the
1479 // equivalent new-loop path. This is true even for the normal "loop-exit"
1480 // condition. All uses of loop-invariant old-loop values now come from (one
1481 // or more) Phis that merge their new-loop equivalents.
1482 //
1483 // This operation leaves the graph in an illegal state: there are two valid
1484 // control edges coming from the loop pre-header to both loop bodies. I'll
1485 // definitely have to hack the graph after running this transform.
1486 //
1487 // From this building block I will further edit edges to perform loop peeling
1488 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1489 //
1490 // Parameter side_by_size_idom:
1491 // When side_by_size_idom is NULL, the dominator tree is constructed for
1492 // the clone loop to dominate the original. Used in construction of
1493 // pre-main-post loop sequence.
1494 // When nonnull, the clone and original are side-by-side, both are
1495 // dominated by the side_by_side_idom node. Used in construction of
1496 // unswitched loops.
1497 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1498 Node* side_by_side_idom) {
1499
1500 if (C->do_vector_loop() && PrintOpto) {
1501 const char* mname = C->method()->name()->as_quoted_ascii();
1502 if (mname != NULL) {
1503 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1504 }
1505 }
1506
1507 CloneMap& cm = C->clone_map();
1508 Dict* dict = cm.dict();
1509 if (C->do_vector_loop()) {
1510 cm.set_clone_idx(cm.max_gen()+1);
1511 #ifndef PRODUCT
1512 if (PrintOpto) {
1513 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1514 loop->dump_head();
1515 }
1516 #endif
1517 }
1518
1519 // Step 1: Clone the loop body. Make the old->new mapping.
1520 uint i;
1521 for( i = 0; i < loop->_body.size(); i++ ) {
1522 Node *old = loop->_body.at(i);
1523 Node *nnn = old->clone();
1524 old_new.map( old->_idx, nnn );
1525 if (C->do_vector_loop()) {
1526 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1527 }
1528 _igvn.register_new_node_with_optimizer(nnn);
1529 }
1530
1531
1532 // Step 2: Fix the edges in the new body. If the old input is outside the
1533 // loop use it. If the old input is INside the loop, use the corresponding
1534 // new node instead.
1535 for( i = 0; i < loop->_body.size(); i++ ) {
1536 Node *old = loop->_body.at(i);
1537 Node *nnn = old_new[old->_idx];
1538 // Fix CFG/Loop controlling the new node
1539 if (has_ctrl(old)) {
1540 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1541 } else {
1542 set_loop(nnn, loop->_parent);
1543 if (old->outcnt() > 0) {
1544 set_idom( nnn, old_new[idom(old)->_idx], dd );
1545 }
1546 }
1547 // Correct edges to the new node
1548 for( uint j = 0; j < nnn->req(); j++ ) {
1549 Node *n = nnn->in(j);
1550 if( n ) {
1551 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1552 if( loop->is_member( old_in_loop ) )
1553 nnn->set_req(j, old_new[n->_idx]);
1554 }
1555 }
1556 _igvn.hash_find_insert(nnn);
1557 }
1558 Node *newhead = old_new[loop->_head->_idx];
1559 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1560
1561
1562 // Step 3: Now fix control uses. Loop varying control uses have already
1563 // been fixed up (as part of all input edges in Step 2). Loop invariant
1564 // control uses must be either an IfFalse or an IfTrue. Make a merge
1565 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1566 // refer to this.
1567 ResourceArea *area = Thread::current()->resource_area();
1568 Node_List worklist(area);
1569 uint new_counter = C->unique();
1570 for( i = 0; i < loop->_body.size(); i++ ) {
1571 Node* old = loop->_body.at(i);
1572 if( !old->is_CFG() ) continue;
1573 Node* nnn = old_new[old->_idx];
1574
1575 // Copy uses to a worklist, so I can munge the def-use info
1576 // with impunity.
1577 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1578 worklist.push(old->fast_out(j));
1579
1580 while( worklist.size() ) { // Visit all uses
1581 Node *use = worklist.pop();
1582 if (!has_node(use)) continue; // Ignore dead nodes
1583 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1584 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1585 // Both OLD and USE are CFG nodes here.
1586 assert( use->is_Proj(), "" );
1587
1588 // Clone the loop exit control projection
1589 Node *newuse = use->clone();
1590 if (C->do_vector_loop()) {
1591 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1592 }
1593 newuse->set_req(0,nnn);
1594 _igvn.register_new_node_with_optimizer(newuse);
1595 set_loop(newuse, use_loop);
1596 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1597
1598 // We need a Region to merge the exit from the peeled body and the
1599 // exit from the old loop body.
1600 RegionNode *r = new RegionNode(3);
1601 // Map the old use to the new merge point
1602 old_new.map( use->_idx, r );
1603 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1604 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1605
1606 // The original user of 'use' uses 'r' instead.
1607 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1608 Node* useuse = use->last_out(l);
1609 _igvn.rehash_node_delayed(useuse);
1610 uint uses_found = 0;
1611 if( useuse->in(0) == use ) {
1612 useuse->set_req(0, r);
1613 uses_found++;
1614 if( useuse->is_CFG() ) {
1615 assert( dom_depth(useuse) > dd_r, "" );
1616 set_idom(useuse, r, dom_depth(useuse));
1617 }
1618 }
1619 for( uint k = 1; k < useuse->req(); k++ ) {
1620 if( useuse->in(k) == use ) {
1621 useuse->set_req(k, r);
1622 uses_found++;
1623 }
1624 }
1625 l -= uses_found; // we deleted 1 or more copies of this edge
1626 }
1627
1628 // Now finish up 'r'
1629 r->set_req( 1, newuse );
1630 r->set_req( 2, use );
1631 _igvn.register_new_node_with_optimizer(r);
1632 set_loop(r, use_loop);
1633 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1634 } // End of if a loop-exit test
1635 }
1636 }
1637
1638 // Step 4: If loop-invariant use is not control, it must be dominated by a
1639 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1640 // there if needed. Make a Phi there merging old and new used values.
1641 Node_List *split_if_set = NULL;
1642 Node_List *split_bool_set = NULL;
1643 Node_List *split_cex_set = NULL;
1644 for( i = 0; i < loop->_body.size(); i++ ) {
1645 Node* old = loop->_body.at(i);
1646 Node* nnn = old_new[old->_idx];
1647 // Copy uses to a worklist, so I can munge the def-use info
1648 // with impunity.
1649 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1650 worklist.push(old->fast_out(j));
1651
1652 while( worklist.size() ) {
1653 Node *use = worklist.pop();
1654 if (!has_node(use)) continue; // Ignore dead nodes
1655 if (use->in(0) == C->top()) continue;
1656 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1657 // Check for data-use outside of loop - at least one of OLD or USE
1658 // must not be a CFG node.
1659 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1660
1661 // If the Data use is an IF, that means we have an IF outside of the
1662 // loop that is switching on a condition that is set inside of the
1663 // loop. Happens if people set a loop-exit flag; then test the flag
1664 // in the loop to break the loop, then test is again outside of the
1665 // loop to determine which way the loop exited.
1666 // Loop predicate If node connects to Bool node through Opaque1 node.
1667 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1668 // Since this code is highly unlikely, we lazily build the worklist
1669 // of such Nodes to go split.
1670 if( !split_if_set )
1671 split_if_set = new Node_List(area);
1672 split_if_set->push(use);
1673 }
1674 if( use->is_Bool() ) {
1675 if( !split_bool_set )
1676 split_bool_set = new Node_List(area);
1677 split_bool_set->push(use);
1678 }
1679 if( use->Opcode() == Op_CreateEx ) {
1680 if( !split_cex_set )
1681 split_cex_set = new Node_List(area);
1682 split_cex_set->push(use);
1683 }
1684
1685
1686 // Get "block" use is in
1687 uint idx = 0;
1688 while( use->in(idx) != old ) idx++;
1689 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1690 assert( !loop->is_member( get_loop( prev ) ), "" );
1691 Node *cfg = prev->_idx >= new_counter
1692 ? prev->in(2)
1693 : idom(prev);
1694 if( use->is_Phi() ) // Phi use is in prior block
1695 cfg = prev->in(idx); // NOT in block of Phi itself
1696 if (cfg->is_top()) { // Use is dead?
1697 _igvn.replace_input_of(use, idx, C->top());
1698 continue;
1699 }
1700
1701 while( !loop->is_member( get_loop( cfg ) ) ) {
1702 prev = cfg;
1703 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1704 }
1705 // If the use occurs after merging several exits from the loop, then
1706 // old value must have dominated all those exits. Since the same old
1707 // value was used on all those exits we did not need a Phi at this
1708 // merge point. NOW we do need a Phi here. Each loop exit value
1709 // is now merged with the peeled body exit; each exit gets its own
1710 // private Phi and those Phis need to be merged here.
1711 Node *phi;
1712 if( prev->is_Region() ) {
1713 if( idx == 0 ) { // Updating control edge?
1714 phi = prev; // Just use existing control
1715 } else { // Else need a new Phi
1716 phi = PhiNode::make( prev, old );
1717 // Now recursively fix up the new uses of old!
1718 for( uint i = 1; i < prev->req(); i++ ) {
1719 worklist.push(phi); // Onto worklist once for each 'old' input
1720 }
1721 }
1722 } else {
1723 // Get new RegionNode merging old and new loop exits
1724 prev = old_new[prev->_idx];
1725 assert( prev, "just made this in step 7" );
1726 if( idx == 0 ) { // Updating control edge?
1727 phi = prev; // Just use existing control
1728 } else { // Else need a new Phi
1729 // Make a new Phi merging data values properly
1730 phi = PhiNode::make( prev, old );
1731 phi->set_req( 1, nnn );
1732 }
1733 }
1734 // If inserting a new Phi, check for prior hits
1735 if( idx != 0 ) {
1736 Node *hit = _igvn.hash_find_insert(phi);
1737 if( hit == NULL ) {
1738 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1739 } else { // or
1740 // Remove the new phi from the graph and use the hit
1741 _igvn.remove_dead_node(phi);
1742 phi = hit; // Use existing phi
1743 }
1744 set_ctrl(phi, prev);
1745 }
1746 // Make 'use' use the Phi instead of the old loop body exit value
1747 _igvn.replace_input_of(use, idx, phi);
1748 if( use->_idx >= new_counter ) { // If updating new phis
1749 // Not needed for correctness, but prevents a weak assert
1750 // in AddPNode from tripping (when we end up with different
1751 // base & derived Phis that will become the same after
1752 // IGVN does CSE).
1753 Node *hit = _igvn.hash_find_insert(use);
1754 if( hit ) // Go ahead and re-hash for hits.
1755 _igvn.replace_node( use, hit );
1756 }
1757
1758 // If 'use' was in the loop-exit block, it now needs to be sunk
1759 // below the post-loop merge point.
1760 sink_use( use, prev );
1761 }
1762 }
1763 }
1764
1765 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1766 // the loop uses a condition set in the loop. The original IF probably
1767 // takes control from one or more OLD Regions (which in turn get from NEW
1768 // Regions). In any case, there will be a set of Phis for each merge point
1769 // from the IF up to where the original BOOL def exists the loop.
1770 if( split_if_set ) {
1771 while( split_if_set->size() ) {
1772 Node *iff = split_if_set->pop();
1773 if( iff->in(1)->is_Phi() ) {
1774 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1775 _igvn.replace_input_of(iff, 1, b);
1776 }
1777 }
1778 }
1779 if( split_bool_set ) {
1780 while( split_bool_set->size() ) {
1781 Node *b = split_bool_set->pop();
1782 Node *phi = b->in(1);
1783 assert( phi->is_Phi(), "" );
1784 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1785 _igvn.replace_input_of(b, 1, cmp);
1786 }
1787 }
1788 if( split_cex_set ) {
1789 while( split_cex_set->size() ) {
1790 Node *b = split_cex_set->pop();
1791 assert( b->in(0)->is_Region(), "" );
1792 assert( b->in(1)->is_Phi(), "" );
1793 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1794 split_up( b, b->in(0), NULL );
1795 }
1796 }
1797
1798 }
1799
1800
1801 //---------------------- stride_of_possible_iv -------------------------------------
1802 // Looks for an iff/bool/comp with one operand of the compare
1803 // being a cycle involving an add and a phi,
1804 // with an optional truncation (left-shift followed by a right-shift)
1805 // of the add. Returns zero if not an iv.
1806 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1807 Node* trunc1 = NULL;
1808 Node* trunc2 = NULL;
1809 const TypeInt* ttype = NULL;
1810 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1811 return 0;
1812 }
1813 BoolNode* bl = iff->in(1)->as_Bool();
1814 Node* cmp = bl->in(1);
1815 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1816 return 0;
1817 }
1818 // Must have an invariant operand
1819 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1820 return 0;
1821 }
1822 Node* add2 = NULL;
1823 Node* cmp1 = cmp->in(1);
1824 if (cmp1->is_Phi()) {
1825 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1826 Node* phi = cmp1;
1827 for (uint i = 1; i < phi->req(); i++) {
1828 Node* in = phi->in(i);
1829 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1830 &trunc1, &trunc2, &ttype);
1831 if (add && add->in(1) == phi) {
1832 add2 = add->in(2);
1833 break;
1834 }
1835 }
1836 } else {
1837 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1838 Node* addtrunc = cmp1;
1839 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1840 &trunc1, &trunc2, &ttype);
1841 if (add && add->in(1)->is_Phi()) {
1842 Node* phi = add->in(1);
1843 for (uint i = 1; i < phi->req(); i++) {
1844 if (phi->in(i) == addtrunc) {
1845 add2 = add->in(2);
1846 break;
1847 }
1848 }
1849 }
1850 }
1851 if (add2 != NULL) {
1852 const TypeInt* add2t = _igvn.type(add2)->is_int();
1853 if (add2t->is_con()) {
1854 return add2t->get_con();
1855 }
1856 }
1857 return 0;
1858 }
1859
1860
1861 //---------------------- stay_in_loop -------------------------------------
1862 // Return the (unique) control output node that's in the loop (if it exists.)
1863 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1864 Node* unique = NULL;
1865 if (!n) return NULL;
1866 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1867 Node* use = n->fast_out(i);
1868 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1869 if (unique != NULL) {
1870 return NULL;
1871 }
1872 unique = use;
1873 }
1874 }
1875 return unique;
1876 }
1877
1878 //------------------------------ register_node -------------------------------------
1879 // Utility to register node "n" with PhaseIdealLoop
1880 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1881 _igvn.register_new_node_with_optimizer(n);
1882 loop->_body.push(n);
1883 if (n->is_CFG()) {
1884 set_loop(n, loop);
1885 set_idom(n, pred, ddepth);
1886 } else {
1887 set_ctrl(n, pred);
1888 }
1889 }
1890
1891 //------------------------------ proj_clone -------------------------------------
1892 // Utility to create an if-projection
1893 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1894 ProjNode* c = p->clone()->as_Proj();
1895 c->set_req(0, iff);
1896 return c;
1897 }
1898
1899 //------------------------------ short_circuit_if -------------------------------------
1900 // Force the iff control output to be the live_proj
1901 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1902 guarantee(live_proj != NULL, "null projection");
1903 int proj_con = live_proj->_con;
1904 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1905 Node *con = _igvn.intcon(proj_con);
1906 set_ctrl(con, C->root());
1907 if (iff) {
1908 iff->set_req(1, con);
1909 }
1910 return con;
1911 }
1912
1913 //------------------------------ insert_if_before_proj -------------------------------------
1914 // Insert a new if before an if projection (* - new node)
1915 //
1916 // before
1917 // if(test)
1918 // / \
1919 // v v
1920 // other-proj proj (arg)
1921 //
1922 // after
1923 // if(test)
1924 // / \
1925 // / v
1926 // | * proj-clone
1927 // v |
1928 // other-proj v
1929 // * new_if(relop(cmp[IU](left,right)))
1930 // / \
1931 // v v
1932 // * new-proj proj
1933 // (returned)
1934 //
1935 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1936 IfNode* iff = proj->in(0)->as_If();
1937 IdealLoopTree *loop = get_loop(proj);
1938 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1939 int ddepth = dom_depth(proj);
1940
1941 _igvn.rehash_node_delayed(iff);
1942 _igvn.rehash_node_delayed(proj);
1943
1944 proj->set_req(0, NULL); // temporary disconnect
1945 ProjNode* proj2 = proj_clone(proj, iff);
1946 register_node(proj2, loop, iff, ddepth);
1947
1948 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1949 register_node(cmp, loop, proj2, ddepth);
1950
1951 BoolNode* bol = new BoolNode(cmp, relop);
1952 register_node(bol, loop, proj2, ddepth);
1953
1954 int opcode = iff->Opcode();
1955 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
1956 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
1957 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
1958 register_node(new_if, loop, proj2, ddepth);
1959
1960 proj->set_req(0, new_if); // reattach
1961 set_idom(proj, new_if, ddepth);
1962
1963 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1964 guarantee(new_exit != NULL, "null exit node");
1965 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1966
1967 return new_exit;
1968 }
1969
1970 //------------------------------ insert_region_before_proj -------------------------------------
1971 // Insert a region before an if projection (* - new node)
1972 //
1973 // before
1974 // if(test)
1975 // / |
1976 // v |
1977 // proj v
1978 // other-proj
1979 //
1980 // after
1981 // if(test)
1982 // / |
1983 // v |
1984 // * proj-clone v
1985 // | other-proj
1986 // v
1987 // * new-region
1988 // |
1989 // v
1990 // * dum_if
1991 // / \
1992 // v \
1993 // * dum-proj v
1994 // proj
1995 //
1996 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1997 IfNode* iff = proj->in(0)->as_If();
1998 IdealLoopTree *loop = get_loop(proj);
1999 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2000 int ddepth = dom_depth(proj);
2001
2002 _igvn.rehash_node_delayed(iff);
2003 _igvn.rehash_node_delayed(proj);
2004
2005 proj->set_req(0, NULL); // temporary disconnect
2006 ProjNode* proj2 = proj_clone(proj, iff);
2007 register_node(proj2, loop, iff, ddepth);
2008
2009 RegionNode* reg = new RegionNode(2);
2010 reg->set_req(1, proj2);
2011 register_node(reg, loop, iff, ddepth);
2012
2013 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2014 register_node(dum_if, loop, reg, ddepth);
2015
2016 proj->set_req(0, dum_if); // reattach
2017 set_idom(proj, dum_if, ddepth);
2018
2019 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2020 register_node(dum_proj, loop, dum_if, ddepth);
2021
2022 return reg;
2023 }
2024
2025 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2026 // Clone a signed compare loop exit from an unsigned compare and
2027 // insert it before the unsigned cmp on the stay-in-loop path.
2028 // All new nodes inserted in the dominator tree between the original
2029 // if and it's projections. The original if test is replaced with
2030 // a constant to force the stay-in-loop path.
2031 //
2032 // This is done to make sure that the original if and it's projections
2033 // still dominate the same set of control nodes, that the ctrl() relation
2034 // from data nodes to them is preserved, and that their loop nesting is
2035 // preserved.
2036 //
2037 // before
2038 // if(i <u limit) unsigned compare loop exit
2039 // / |
2040 // v v
2041 // exit-proj stay-in-loop-proj
2042 //
2043 // after
2044 // if(stay-in-loop-const) original if
2045 // / |
2046 // / v
2047 // / if(i < limit) new signed test
2048 // / / |
2049 // / / v
2050 // / / if(i <u limit) new cloned unsigned test
2051 // / / / |
2052 // v v v |
2053 // region |
2054 // | |
2055 // dum-if |
2056 // / | |
2057 // ether | |
2058 // v v
2059 // exit-proj stay-in-loop-proj
2060 //
2061 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2062 const bool Signed = true;
2063 const bool Unsigned = false;
2064
2065 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2066 if (bol->_test._test != BoolTest::lt) return NULL;
2067 CmpNode* cmpu = bol->in(1)->as_Cmp();
2068 if (cmpu->Opcode() != Op_CmpU) return NULL;
2069 int stride = stride_of_possible_iv(if_cmpu);
2070 if (stride == 0) return NULL;
2071
2072 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2073 guarantee(lp_proj != NULL, "null loop node");
2074
2075 ProjNode* lp_continue = lp_proj->as_Proj();
2076 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2077
2078 Node* limit = NULL;
2079 if (stride > 0) {
2080 limit = cmpu->in(2);
2081 } else {
2082 limit = _igvn.makecon(TypeInt::ZERO);
2083 set_ctrl(limit, C->root());
2084 }
2085 // Create a new region on the exit path
2086 RegionNode* reg = insert_region_before_proj(lp_exit);
2087 guarantee(reg != NULL, "null region node");
2088
2089 // Clone the if-cmpu-true-false using a signed compare
2090 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2091 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2092 reg->add_req(cmpi_exit);
2093
2094 // Clone the if-cmpu-true-false
2095 BoolTest::mask rel_u = bol->_test._test;
2096 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2097 reg->add_req(cmpu_exit);
2098
2099 // Force original if to stay in loop.
2100 short_circuit_if(if_cmpu, lp_continue);
2101
2102 return cmpi_exit->in(0)->as_If();
2103 }
2104
2105 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2106 // Remove a previously inserted signed compare loop exit.
2107 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2108 Node* lp_proj = stay_in_loop(if_cmp, loop);
2109 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2110 stay_in_loop(lp_proj, loop)->is_If() &&
2111 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2112 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2113 set_ctrl(con, C->root());
2114 if_cmp->set_req(1, con);
2115 }
2116
2117 //------------------------------ scheduled_nodelist -------------------------------------
2118 // Create a post order schedule of nodes that are in the
2119 // "member" set. The list is returned in "sched".
2120 // The first node in "sched" is the loop head, followed by
2121 // nodes which have no inputs in the "member" set, and then
2122 // followed by the nodes that have an immediate input dependence
2123 // on a node in "sched".
2124 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2125
2126 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2127 Arena *a = Thread::current()->resource_area();
2128 VectorSet visited(a);
2129 Node_Stack nstack(a, loop->_body.size());
2130
2131 Node* n = loop->_head; // top of stack is cached in "n"
2132 uint idx = 0;
2133 visited.set(n->_idx);
2134
2135 // Initially push all with no inputs from within member set
2136 for(uint i = 0; i < loop->_body.size(); i++ ) {
2137 Node *elt = loop->_body.at(i);
2138 if (member.test(elt->_idx)) {
2139 bool found = false;
2140 for (uint j = 0; j < elt->req(); j++) {
2141 Node* def = elt->in(j);
2142 if (def && member.test(def->_idx) && def != elt) {
2143 found = true;
2144 break;
2145 }
2146 }
2147 if (!found && elt != loop->_head) {
2148 nstack.push(n, idx);
2149 n = elt;
2150 assert(!visited.test(n->_idx), "not seen yet");
2151 visited.set(n->_idx);
2152 }
2153 }
2154 }
2155
2156 // traverse out's that are in the member set
2157 while (true) {
2158 if (idx < n->outcnt()) {
2159 Node* use = n->raw_out(idx);
2160 idx++;
2161 if (!visited.test_set(use->_idx)) {
2162 if (member.test(use->_idx)) {
2163 nstack.push(n, idx);
2164 n = use;
2165 idx = 0;
2166 }
2167 }
2168 } else {
2169 // All outputs processed
2170 sched.push(n);
2171 if (nstack.is_empty()) break;
2172 n = nstack.node();
2173 idx = nstack.index();
2174 nstack.pop();
2175 }
2176 }
2177 }
2178
2179
2180 //------------------------------ has_use_in_set -------------------------------------
2181 // Has a use in the vector set
2182 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2183 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2184 Node* use = n->fast_out(j);
2185 if (vset.test(use->_idx)) {
2186 return true;
2187 }
2188 }
2189 return false;
2190 }
2191
2192
2193 //------------------------------ has_use_internal_to_set -------------------------------------
2194 // Has use internal to the vector set (ie. not in a phi at the loop head)
2195 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2196 Node* head = loop->_head;
2197 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2198 Node* use = n->fast_out(j);
2199 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2200 return true;
2201 }
2202 }
2203 return false;
2204 }
2205
2206
2207 //------------------------------ clone_for_use_outside_loop -------------------------------------
2208 // clone "n" for uses that are outside of loop
2209 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2210 int cloned = 0;
2211 assert(worklist.size() == 0, "should be empty");
2212 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2213 Node* use = n->fast_out(j);
2214 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2215 worklist.push(use);
2216 }
2217 }
2218 while( worklist.size() ) {
2219 Node *use = worklist.pop();
2220 if (!has_node(use) || use->in(0) == C->top()) continue;
2221 uint j;
2222 for (j = 0; j < use->req(); j++) {
2223 if (use->in(j) == n) break;
2224 }
2225 assert(j < use->req(), "must be there");
2226
2227 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2228 Node* n_clone = n->clone();
2229 _igvn.replace_input_of(use, j, n_clone);
2230 cloned++;
2231 Node* use_c;
2232 if (!use->is_Phi()) {
2233 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2234 } else {
2235 // Use in a phi is considered a use in the associated predecessor block
2236 use_c = use->in(0)->in(j);
2237 }
2238 set_ctrl(n_clone, use_c);
2239 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2240 get_loop(use_c)->_body.push(n_clone);
2241 _igvn.register_new_node_with_optimizer(n_clone);
2242 #if !defined(PRODUCT)
2243 if (TracePartialPeeling) {
2244 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2245 }
2246 #endif
2247 }
2248 return cloned;
2249 }
2250
2251
2252 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2253 // clone "n" for special uses that are in the not_peeled region.
2254 // If these def-uses occur in separate blocks, the code generator
2255 // marks the method as not compilable. For example, if a "BoolNode"
2256 // is in a different basic block than the "IfNode" that uses it, then
2257 // the compilation is aborted in the code generator.
2258 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2259 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2260 if (n->is_Phi() || n->is_Load()) {
2261 return;
2262 }
2263 assert(worklist.size() == 0, "should be empty");
2264 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2265 Node* use = n->fast_out(j);
2266 if ( not_peel.test(use->_idx) &&
2267 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2268 use->in(1) == n) {
2269 worklist.push(use);
2270 }
2271 }
2272 if (worklist.size() > 0) {
2273 // clone "n" and insert it between inputs of "n" and the use
2274 Node* n_clone = n->clone();
2275 loop->_body.push(n_clone);
2276 _igvn.register_new_node_with_optimizer(n_clone);
2277 set_ctrl(n_clone, get_ctrl(n));
2278 sink_list.push(n_clone);
2279 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2280 #if !defined(PRODUCT)
2281 if (TracePartialPeeling) {
2282 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2283 }
2284 #endif
2285 while( worklist.size() ) {
2286 Node *use = worklist.pop();
2287 _igvn.rehash_node_delayed(use);
2288 for (uint j = 1; j < use->req(); j++) {
2289 if (use->in(j) == n) {
2290 use->set_req(j, n_clone);
2291 }
2292 }
2293 }
2294 }
2295 }
2296
2297
2298 //------------------------------ insert_phi_for_loop -------------------------------------
2299 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2300 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2301 Node *phi = PhiNode::make(lp, back_edge_val);
2302 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2303 // Use existing phi if it already exists
2304 Node *hit = _igvn.hash_find_insert(phi);
2305 if( hit == NULL ) {
2306 _igvn.register_new_node_with_optimizer(phi);
2307 set_ctrl(phi, lp);
2308 } else {
2309 // Remove the new phi from the graph and use the hit
2310 _igvn.remove_dead_node(phi);
2311 phi = hit;
2312 }
2313 _igvn.replace_input_of(use, idx, phi);
2314 }
2315
2316 #ifdef ASSERT
2317 //------------------------------ is_valid_loop_partition -------------------------------------
2318 // Validate the loop partition sets: peel and not_peel
2319 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2320 VectorSet& not_peel ) {
2321 uint i;
2322 // Check that peel_list entries are in the peel set
2323 for (i = 0; i < peel_list.size(); i++) {
2324 if (!peel.test(peel_list.at(i)->_idx)) {
2325 return false;
2326 }
2327 }
2328 // Check at loop members are in one of peel set or not_peel set
2329 for (i = 0; i < loop->_body.size(); i++ ) {
2330 Node *def = loop->_body.at(i);
2331 uint di = def->_idx;
2332 // Check that peel set elements are in peel_list
2333 if (peel.test(di)) {
2334 if (not_peel.test(di)) {
2335 return false;
2336 }
2337 // Must be in peel_list also
2338 bool found = false;
2339 for (uint j = 0; j < peel_list.size(); j++) {
2340 if (peel_list.at(j)->_idx == di) {
2341 found = true;
2342 break;
2343 }
2344 }
2345 if (!found) {
2346 return false;
2347 }
2348 } else if (not_peel.test(di)) {
2349 if (peel.test(di)) {
2350 return false;
2351 }
2352 } else {
2353 return false;
2354 }
2355 }
2356 return true;
2357 }
2358
2359 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2360 // Ensure a use outside of loop is of the right form
2361 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2362 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2363 return (use->is_Phi() &&
2364 use_c->is_Region() && use_c->req() == 3 &&
2365 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2366 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2367 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2368 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2369 }
2370
2371 //------------------------------ is_valid_clone_loop_form -------------------------------------
2372 // Ensure that all uses outside of loop are of the right form
2373 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2374 uint orig_exit_idx, uint clone_exit_idx) {
2375 uint len = peel_list.size();
2376 for (uint i = 0; i < len; i++) {
2377 Node *def = peel_list.at(i);
2378
2379 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2380 Node *use = def->fast_out(j);
2381 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2382 if (!loop->is_member(get_loop(use_c))) {
2383 // use is not in the loop, check for correct structure
2384 if (use->in(0) == def) {
2385 // Okay
2386 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2387 return false;
2388 }
2389 }
2390 }
2391 }
2392 return true;
2393 }
2394 #endif
2395
2396 //------------------------------ partial_peel -------------------------------------
2397 // Partially peel (aka loop rotation) the top portion of a loop (called
2398 // the peel section below) by cloning it and placing one copy just before
2399 // the new loop head and the other copy at the bottom of the new loop.
2400 //
2401 // before after where it came from
2402 //
2403 // stmt1 stmt1
2404 // loop: stmt2 clone
2405 // stmt2 if condA goto exitA clone
2406 // if condA goto exitA new_loop: new
2407 // stmt3 stmt3 clone
2408 // if !condB goto loop if condB goto exitB clone
2409 // exitB: stmt2 orig
2410 // stmt4 if !condA goto new_loop orig
2411 // exitA: goto exitA
2412 // exitB:
2413 // stmt4
2414 // exitA:
2415 //
2416 // Step 1: find the cut point: an exit test on probable
2417 // induction variable.
2418 // Step 2: schedule (with cloning) operations in the peel
2419 // section that can be executed after the cut into
2420 // the section that is not peeled. This may need
2421 // to clone operations into exit blocks. For
2422 // instance, a reference to A[i] in the not-peel
2423 // section and a reference to B[i] in an exit block
2424 // may cause a left-shift of i by 2 to be placed
2425 // in the peel block. This step will clone the left
2426 // shift into the exit block and sink the left shift
2427 // from the peel to the not-peel section.
2428 // Step 3: clone the loop, retarget the control, and insert
2429 // phis for values that are live across the new loop
2430 // head. This is very dependent on the graph structure
2431 // from clone_loop. It creates region nodes for
2432 // exit control and associated phi nodes for values
2433 // flow out of the loop through that exit. The region
2434 // node is dominated by the clone's control projection.
2435 // So the clone's peel section is placed before the
2436 // new loop head, and the clone's not-peel section is
2437 // forms the top part of the new loop. The original
2438 // peel section forms the tail of the new loop.
2439 // Step 4: update the dominator tree and recompute the
2440 // dominator depth.
2441 //
2442 // orig
2443 //
2444 // stmt1
2445 // |
2446 // v
2447 // loop predicate
2448 // |
2449 // v
2450 // loop<----+
2451 // | |
2452 // stmt2 |
2453 // | |
2454 // v |
2455 // ifA |
2456 // / | |
2457 // v v |
2458 // false true ^ <-- last_peel
2459 // / | |
2460 // / ===|==cut |
2461 // / stmt3 | <-- first_not_peel
2462 // / | |
2463 // | v |
2464 // v ifB |
2465 // exitA: / \ |
2466 // / \ |
2467 // v v |
2468 // false true |
2469 // / \ |
2470 // / ----+
2471 // |
2472 // v
2473 // exitB:
2474 // stmt4
2475 //
2476 //
2477 // after clone loop
2478 //
2479 // stmt1
2480 // |
2481 // v
2482 // loop predicate
2483 // / \
2484 // clone / \ orig
2485 // / \
2486 // / \
2487 // v v
2488 // +---->loop loop<----+
2489 // | | | |
2490 // | stmt2 stmt2 |
2491 // | | | |
2492 // | v v |
2493 // | ifA ifA |
2494 // | | \ / | |
2495 // | v v v v |
2496 // ^ true false false true ^ <-- last_peel
2497 // | | ^ \ / | |
2498 // | cut==|== \ \ / ===|==cut |
2499 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2500 // | | dom | | | |
2501 // | v \ 1v v2 v |
2502 // | ifB regionA ifB |
2503 // | / \ | / \ |
2504 // | / \ v / \ |
2505 // | v v exitA: v v |
2506 // | true false false true |
2507 // | / ^ \ / \ |
2508 // +---- \ \ / ----+
2509 // dom \ /
2510 // \ 1v v2
2511 // regionB
2512 // |
2513 // v
2514 // exitB:
2515 // stmt4
2516 //
2517 //
2518 // after partial peel
2519 //
2520 // stmt1
2521 // |
2522 // v
2523 // loop predicate
2524 // /
2525 // clone / orig
2526 // / TOP
2527 // / \
2528 // v v
2529 // TOP->loop loop----+
2530 // | | |
2531 // stmt2 stmt2 |
2532 // | | |
2533 // v v |
2534 // ifA ifA |
2535 // | \ / | |
2536 // v v v v |
2537 // true false false true | <-- last_peel
2538 // | ^ \ / +------|---+
2539 // +->newloop \ \ / === ==cut | |
2540 // | stmt3 \ \ / TOP | |
2541 // | | dom | | stmt3 | | <-- first_not_peel
2542 // | v \ 1v v2 v | |
2543 // | ifB regionA ifB ^ v
2544 // | / \ | / \ | |
2545 // | / \ v / \ | |
2546 // | v v exitA: v v | |
2547 // | true false false true | |
2548 // | / ^ \ / \ | |
2549 // | | \ \ / v | |
2550 // | | dom \ / TOP | |
2551 // | | \ 1v v2 | |
2552 // ^ v regionB | |
2553 // | | | | |
2554 // | | v ^ v
2555 // | | exitB: | |
2556 // | | stmt4 | |
2557 // | +------------>-----------------+ |
2558 // | |
2559 // +-----------------<---------------------+
2560 //
2561 //
2562 // final graph
2563 //
2564 // stmt1
2565 // |
2566 // v
2567 // loop predicate
2568 // |
2569 // v
2570 // stmt2 clone
2571 // |
2572 // v
2573 // ........> ifA clone
2574 // : / |
2575 // dom / |
2576 // : v v
2577 // : false true
2578 // : | |
2579 // : | v
2580 // : | newloop<-----+
2581 // : | | |
2582 // : | stmt3 clone |
2583 // : | | |
2584 // : | v |
2585 // : | ifB |
2586 // : | / \ |
2587 // : | v v |
2588 // : | false true |
2589 // : | | | |
2590 // : | v stmt2 |
2591 // : | exitB: | |
2592 // : | stmt4 v |
2593 // : | ifA orig |
2594 // : | / \ |
2595 // : | / \ |
2596 // : | v v |
2597 // : | false true |
2598 // : | / \ |
2599 // : v v -----+
2600 // RegionA
2601 // |
2602 // v
2603 // exitA
2604 //
2605 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2606
2607 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2608 if (!loop->_head->is_Loop()) {
2609 return false; }
2610
2611 LoopNode *head = loop->_head->as_Loop();
2612
2613 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2614 return false;
2615 }
2616
2617 // Check for complex exit control
2618 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2619 Node *n = loop->_body.at(ii);
2620 int opc = n->Opcode();
2621 if (n->is_Call() ||
2622 opc == Op_Catch ||
2623 opc == Op_CatchProj ||
2624 opc == Op_Jump ||
2625 opc == Op_JumpProj) {
2626 #if !defined(PRODUCT)
2627 if (TracePartialPeeling) {
2628 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2629 }
2630 #endif
2631 return false;
2632 }
2633 }
2634
2635 int dd = dom_depth(head);
2636
2637 // Step 1: find cut point
2638
2639 // Walk up dominators to loop head looking for first loop exit
2640 // which is executed on every path thru loop.
2641 IfNode *peel_if = NULL;
2642 IfNode *peel_if_cmpu = NULL;
2643
2644 Node *iff = loop->tail();
2645 while( iff != head ) {
2646 if( iff->is_If() ) {
2647 Node *ctrl = get_ctrl(iff->in(1));
2648 if (ctrl->is_top()) return false; // Dead test on live IF.
2649 // If loop-varying exit-test, check for induction variable
2650 if( loop->is_member(get_loop(ctrl)) &&
2651 loop->is_loop_exit(iff) &&
2652 is_possible_iv_test(iff)) {
2653 Node* cmp = iff->in(1)->in(1);
2654 if (cmp->Opcode() == Op_CmpI) {
2655 peel_if = iff->as_If();
2656 } else {
2657 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2658 peel_if_cmpu = iff->as_If();
2659 }
2660 }
2661 }
2662 iff = idom(iff);
2663 }
2664 // Prefer signed compare over unsigned compare.
2665 IfNode* new_peel_if = NULL;
2666 if (peel_if == NULL) {
2667 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2668 return false; // No peel point found
2669 }
2670 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2671 if (new_peel_if == NULL) {
2672 return false; // No peel point found
2673 }
2674 peel_if = new_peel_if;
2675 }
2676 Node* last_peel = stay_in_loop(peel_if, loop);
2677 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2678 if (first_not_peeled == NULL || first_not_peeled == head) {
2679 return false;
2680 }
2681
2682 #if !defined(PRODUCT)
2683 if (TraceLoopOpts) {
2684 tty->print("PartialPeel ");
2685 loop->dump_head();
2686 }
2687
2688 if (TracePartialPeeling) {
2689 tty->print_cr("before partial peel one iteration");
2690 Node_List wl;
2691 Node* t = head->in(2);
2692 while (true) {
2693 wl.push(t);
2694 if (t == head) break;
2695 t = idom(t);
2696 }
2697 while (wl.size() > 0) {
2698 Node* tt = wl.pop();
2699 tt->dump();
2700 if (tt == last_peel) tty->print_cr("-- cut --");
2701 }
2702 }
2703 #endif
2704 ResourceArea *area = Thread::current()->resource_area();
2705 VectorSet peel(area);
2706 VectorSet not_peel(area);
2707 Node_List peel_list(area);
2708 Node_List worklist(area);
2709 Node_List sink_list(area);
2710
2711 // Set of cfg nodes to peel are those that are executable from
2712 // the head through last_peel.
2713 assert(worklist.size() == 0, "should be empty");
2714 worklist.push(head);
2715 peel.set(head->_idx);
2716 while (worklist.size() > 0) {
2717 Node *n = worklist.pop();
2718 if (n != last_peel) {
2719 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2720 Node* use = n->fast_out(j);
2721 if (use->is_CFG() &&
2722 loop->is_member(get_loop(use)) &&
2723 !peel.test_set(use->_idx)) {
2724 worklist.push(use);
2725 }
2726 }
2727 }
2728 }
2729
2730 // Set of non-cfg nodes to peel are those that are control
2731 // dependent on the cfg nodes.
2732 uint i;
2733 for(i = 0; i < loop->_body.size(); i++ ) {
2734 Node *n = loop->_body.at(i);
2735 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2736 if (peel.test(n_c->_idx)) {
2737 peel.set(n->_idx);
2738 } else {
2739 not_peel.set(n->_idx);
2740 }
2741 }
2742
2743 // Step 2: move operations from the peeled section down into the
2744 // not-peeled section
2745
2746 // Get a post order schedule of nodes in the peel region
2747 // Result in right-most operand.
2748 scheduled_nodelist(loop, peel, peel_list );
2749
2750 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2751
2752 // For future check for too many new phis
2753 uint old_phi_cnt = 0;
2754 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2755 Node* use = head->fast_out(j);
2756 if (use->is_Phi()) old_phi_cnt++;
2757 }
2758
2759 #if !defined(PRODUCT)
2760 if (TracePartialPeeling) {
2761 tty->print_cr("\npeeled list");
2762 }
2763 #endif
2764
2765 // Evacuate nodes in peel region into the not_peeled region if possible
2766 uint new_phi_cnt = 0;
2767 uint cloned_for_outside_use = 0;
2768 for (i = 0; i < peel_list.size();) {
2769 Node* n = peel_list.at(i);
2770 #if !defined(PRODUCT)
2771 if (TracePartialPeeling) n->dump();
2772 #endif
2773 bool incr = true;
2774 if ( !n->is_CFG() ) {
2775
2776 if ( has_use_in_set(n, not_peel) ) {
2777
2778 // If not used internal to the peeled region,
2779 // move "n" from peeled to not_peeled region.
2780
2781 if ( !has_use_internal_to_set(n, peel, loop) ) {
2782
2783 // if not pinned and not a load (which maybe anti-dependent on a store)
2784 // and not a CMove (Matcher expects only bool->cmove).
2785 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2786 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2787 sink_list.push(n);
2788 peel >>= n->_idx; // delete n from peel set.
2789 not_peel <<= n->_idx; // add n to not_peel set.
2790 peel_list.remove(i);
2791 incr = false;
2792 #if !defined(PRODUCT)
2793 if (TracePartialPeeling) {
2794 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2795 n->_idx, get_ctrl(n)->_idx);
2796 }
2797 #endif
2798 }
2799 } else {
2800 // Otherwise check for special def-use cases that span
2801 // the peel/not_peel boundary such as bool->if
2802 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2803 new_phi_cnt++;
2804 }
2805 }
2806 }
2807 if (incr) i++;
2808 }
2809
2810 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2811 #if !defined(PRODUCT)
2812 if (TracePartialPeeling) {
2813 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2814 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2815 }
2816 #endif
2817 if (new_peel_if != NULL) {
2818 remove_cmpi_loop_exit(new_peel_if, loop);
2819 }
2820 // Inhibit more partial peeling on this loop
2821 assert(!head->is_partial_peel_loop(), "not partial peeled");
2822 head->mark_partial_peel_failed();
2823 if (cloned_for_outside_use > 0) {
2824 // Terminate this round of loop opts because
2825 // the graph outside this loop was changed.
2826 C->set_major_progress();
2827 return true;
2828 }
2829 return false;
2830 }
2831
2832 // Step 3: clone loop, retarget control, and insert new phis
2833
2834 // Create new loop head for new phis and to hang
2835 // the nodes being moved (sinked) from the peel region.
2836 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2837 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2838 _igvn.register_new_node_with_optimizer(new_head);
2839 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2840 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2841 set_loop(new_head, loop);
2842 loop->_body.push(new_head);
2843 not_peel.set(new_head->_idx);
2844 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2845 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2846
2847 while (sink_list.size() > 0) {
2848 Node* n = sink_list.pop();
2849 set_ctrl(n, new_head);
2850 }
2851
2852 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2853
2854 clone_loop( loop, old_new, dd );
2855
2856 const uint clone_exit_idx = 1;
2857 const uint orig_exit_idx = 2;
2858 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2859
2860 Node* head_clone = old_new[head->_idx];
2861 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2862 Node* orig_tail_clone = head_clone->in(2);
2863
2864 // Add phi if "def" node is in peel set and "use" is not
2865
2866 for(i = 0; i < peel_list.size(); i++ ) {
2867 Node *def = peel_list.at(i);
2868 if (!def->is_CFG()) {
2869 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2870 Node *use = def->fast_out(j);
2871 if (has_node(use) && use->in(0) != C->top() &&
2872 (!peel.test(use->_idx) ||
2873 (use->is_Phi() && use->in(0) == head)) ) {
2874 worklist.push(use);
2875 }
2876 }
2877 while( worklist.size() ) {
2878 Node *use = worklist.pop();
2879 for (uint j = 1; j < use->req(); j++) {
2880 Node* n = use->in(j);
2881 if (n == def) {
2882
2883 // "def" is in peel set, "use" is not in peel set
2884 // or "use" is in the entry boundary (a phi) of the peel set
2885
2886 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2887
2888 if ( loop->is_member(get_loop( use_c )) ) {
2889 // use is in loop
2890 if (old_new[use->_idx] != NULL) { // null for dead code
2891 Node* use_clone = old_new[use->_idx];
2892 _igvn.replace_input_of(use, j, C->top());
2893 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2894 }
2895 } else {
2896 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2897 // use is not in the loop, check if the live range includes the cut
2898 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2899 if (not_peel.test(lp_if->_idx)) {
2900 assert(j == orig_exit_idx, "use from original loop");
2901 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2902 }
2903 }
2904 }
2905 }
2906 }
2907 }
2908 }
2909
2910 // Step 3b: retarget control
2911
2912 // Redirect control to the new loop head if a cloned node in
2913 // the not_peeled region has control that points into the peeled region.
2914 // This necessary because the cloned peeled region will be outside
2915 // the loop.
2916 // from to
2917 // cloned-peeled <---+
2918 // new_head_clone: | <--+
2919 // cloned-not_peeled in(0) in(0)
2920 // orig-peeled
2921
2922 for(i = 0; i < loop->_body.size(); i++ ) {
2923 Node *n = loop->_body.at(i);
2924 if (!n->is_CFG() && n->in(0) != NULL &&
2925 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2926 Node* n_clone = old_new[n->_idx];
2927 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2928 }
2929 }
2930
2931 // Backedge of the surviving new_head (the clone) is original last_peel
2932 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2933
2934 // Cut first node in original not_peel set
2935 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2936 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2937 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2938
2939 // Copy head_clone back-branch info to original head
2940 // and remove original head's loop entry and
2941 // clone head's back-branch
2942 _igvn.rehash_node_delayed(head); // Multiple edge updates
2943 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2944 head->set_req(LoopNode::LoopBackControl, C->top());
2945 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2946
2947 // Similarly modify the phis
2948 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2949 Node* use = head->fast_out(k);
2950 if (use->is_Phi() && use->outcnt() > 0) {
2951 Node* use_clone = old_new[use->_idx];
2952 _igvn.rehash_node_delayed(use); // Multiple edge updates
2953 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2954 use->set_req(LoopNode::LoopBackControl, C->top());
2955 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2956 }
2957 }
2958
2959 // Step 4: update dominator tree and dominator depth
2960
2961 set_idom(head, orig_tail_clone, dd);
2962 recompute_dom_depth();
2963
2964 // Inhibit more partial peeling on this loop
2965 new_head_clone->set_partial_peel_loop();
2966 C->set_major_progress();
2967 loop->record_for_igvn();
2968
2969 #if !defined(PRODUCT)
2970 if (TracePartialPeeling) {
2971 tty->print_cr("\nafter partial peel one iteration");
2972 Node_List wl(area);
2973 Node* t = last_peel;
2974 while (true) {
2975 wl.push(t);
2976 if (t == head_clone) break;
2977 t = idom(t);
2978 }
2979 while (wl.size() > 0) {
2980 Node* tt = wl.pop();
2981 if (tt == head) tty->print_cr("orig head");
2982 else if (tt == new_head_clone) tty->print_cr("new head");
2983 else if (tt == head_clone) tty->print_cr("clone head");
2984 tt->dump();
2985 }
2986 }
2987 #endif
2988 return true;
2989 }
2990
2991 //------------------------------reorg_offsets----------------------------------
2992 // Reorganize offset computations to lower register pressure. Mostly
2993 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2994 // then alive with the post-incremented trip counter forcing an extra
2995 // register move)
2996 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2997 // Perform it only for canonical counted loops.
2998 // Loop's shape could be messed up by iteration_split_impl.
2999 if (!loop->_head->is_CountedLoop())
3000 return;
3001 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3002 return;
3003
3004 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3005 CountedLoopEndNode *cle = cl->loopexit();
3006 Node *exit = cle->proj_out(false);
3007 Node *phi = cl->phi();
3008
3009 // Check for the special case of folks using the pre-incremented
3010 // trip-counter on the fall-out path (forces the pre-incremented
3011 // and post-incremented trip counter to be live at the same time).
3012 // Fix this by adjusting to use the post-increment trip counter.
3013
3014 bool progress = true;
3015 while (progress) {
3016 progress = false;
3017 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3018 Node* use = phi->fast_out(i); // User of trip-counter
3019 if (!has_ctrl(use)) continue;
3020 Node *u_ctrl = get_ctrl(use);
3021 if (use->is_Phi()) {
3022 u_ctrl = NULL;
3023 for (uint j = 1; j < use->req(); j++)
3024 if (use->in(j) == phi)
3025 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3026 }
3027 IdealLoopTree *u_loop = get_loop(u_ctrl);
3028 // Look for loop-invariant use
3029 if (u_loop == loop) continue;
3030 if (loop->is_member(u_loop)) continue;
3031 // Check that use is live out the bottom. Assuming the trip-counter
3032 // update is right at the bottom, uses of of the loop middle are ok.
3033 if (dom_lca(exit, u_ctrl) != exit) continue;
3034 // Hit! Refactor use to use the post-incremented tripcounter.
3035 // Compute a post-increment tripcounter.
3036 Node *opaq = new Opaque2Node( C, cle->incr() );
3037 register_new_node(opaq, exit);
3038 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3039 set_ctrl(neg_stride, C->root());
3040 Node *post = new AddINode( opaq, neg_stride);
3041 register_new_node(post, exit);
3042 _igvn.rehash_node_delayed(use);
3043 for (uint j = 1; j < use->req(); j++) {
3044 if (use->in(j) == phi)
3045 use->set_req(j, post);
3046 }
3047 // Since DU info changed, rerun loop
3048 progress = true;
3049 break;
3050 }
3051 }
3052
3053 }