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