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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/castnode.hpp"
30 #include "opto/connode.hpp"
31 #include "opto/castnode.hpp"
32 #include "opto/divnode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/matcher.hpp"
35 #include "opto/mulnode.hpp"
36 #include "opto/movenode.hpp"
37 #include "opto/opaquenode.hpp"
38 #include "opto/rootnode.hpp"
39 #include "opto/subnode.hpp"
40
41 //=============================================================================
42 //------------------------------split_thru_phi---------------------------------
43 // Split Node 'n' through merge point if there is enough win.
44 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
45 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
46 // ConvI2L may have type information on it which is unsafe to push up
47 // so disable this for now
48 return NULL;
49 }
50
51 // Splitting range check CastIIs through a loop induction Phi can
52 // cause new Phis to be created that are left unrelated to the loop
53 // induction Phi and prevent optimizations (vectorization)
54 if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
55 region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
56 return NULL;
57 }
58
59 // Value types should not be split through Phis because they cannot be merged
60 // through Phi nodes but each value input needs to be merged individually.
61 if (n->is_ValueType()) {
62 return NULL;
63 }
64
65 int wins = 0;
66 assert(!n->is_CFG(), "");
67 assert(region->is_Region(), "");
68
69 const Type* type = n->bottom_type();
70 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
71 Node *phi;
72 if (t_oop != NULL && t_oop->is_known_instance_field()) {
73 int iid = t_oop->instance_id();
74 int index = C->get_alias_index(t_oop);
75 int offset = t_oop->offset();
76 phi = new PhiNode(region, type, NULL, iid, index, offset);
77 } else {
78 phi = PhiNode::make_blank(region, n);
79 }
80 uint old_unique = C->unique();
81 for (uint i = 1; i < region->req(); i++) {
82 Node *x;
83 Node* the_clone = NULL;
84 if (region->in(i) == C->top()) {
85 x = C->top(); // Dead path? Use a dead data op
86 } else {
87 x = n->clone(); // Else clone up the data op
88 the_clone = x; // Remember for possible deletion.
89 // Alter data node to use pre-phi inputs
90 if (n->in(0) == region)
91 x->set_req( 0, region->in(i) );
92 for (uint j = 1; j < n->req(); j++) {
93 Node *in = n->in(j);
94 if (in->is_Phi() && in->in(0) == region)
95 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
96 }
97 }
98 // Check for a 'win' on some paths
99 const Type *t = x->Value(&_igvn);
100
101 bool singleton = t->singleton();
102
103 // A TOP singleton indicates that there are no possible values incoming
104 // along a particular edge. In most cases, this is OK, and the Phi will
105 // be eliminated later in an Ideal call. However, we can't allow this to
106 // happen if the singleton occurs on loop entry, as the elimination of
107 // the PhiNode may cause the resulting node to migrate back to a previous
108 // loop iteration.
109 if (singleton && t == Type::TOP) {
110 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
111 // irreducible loop may not be indicated by an affirmative is_Loop());
112 // therefore, the only top we can split thru a phi is on a backedge of
113 // a loop.
114 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
115 }
116
117 if (singleton) {
118 wins++;
119 x = ((PhaseGVN&)_igvn).makecon(t);
120 } else {
121 // We now call Identity to try to simplify the cloned node.
122 // Note that some Identity methods call phase->type(this).
123 // Make sure that the type array is big enough for
124 // our new node, even though we may throw the node away.
125 // (Note: This tweaking with igvn only works because x is a new node.)
126 _igvn.set_type(x, t);
127 // If x is a TypeNode, capture any more-precise type permanently into Node
128 // otherwise it will be not updated during igvn->transform since
129 // igvn->type(x) is set to x->Value() already.
130 x->raise_bottom_type(t);
131 Node *y = x->Identity(&_igvn);
132 if (y != x) {
133 wins++;
134 x = y;
135 } else {
136 y = _igvn.hash_find(x);
137 if (y) {
138 wins++;
139 x = y;
140 } else {
141 // Else x is a new node we are keeping
142 // We do not need register_new_node_with_optimizer
143 // because set_type has already been called.
144 _igvn._worklist.push(x);
145 }
146 }
147 }
148 if (x != the_clone && the_clone != NULL)
149 _igvn.remove_dead_node(the_clone);
150 phi->set_req( i, x );
151 }
152 // Too few wins?
153 if (wins <= policy) {
154 _igvn.remove_dead_node(phi);
155 return NULL;
156 }
157
158 // Record Phi
159 register_new_node( phi, region );
160
161 for (uint i2 = 1; i2 < phi->req(); i2++) {
162 Node *x = phi->in(i2);
163 // If we commoned up the cloned 'x' with another existing Node,
164 // the existing Node picks up a new use. We need to make the
165 // existing Node occur higher up so it dominates its uses.
166 Node *old_ctrl;
167 IdealLoopTree *old_loop;
168
169 if (x->is_Con()) {
170 // Constant's control is always root.
171 set_ctrl(x, C->root());
172 continue;
173 }
174 // The occasional new node
175 if (x->_idx >= old_unique) { // Found a new, unplaced node?
176 old_ctrl = NULL;
177 old_loop = NULL; // Not in any prior loop
178 } else {
179 old_ctrl = get_ctrl(x);
180 old_loop = get_loop(old_ctrl); // Get prior loop
181 }
182 // New late point must dominate new use
183 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
184 if (new_ctrl == old_ctrl) // Nothing is changed
185 continue;
186
187 IdealLoopTree *new_loop = get_loop(new_ctrl);
188
189 // Don't move x into a loop if its uses are
190 // outside of loop. Otherwise x will be cloned
191 // for each use outside of this loop.
192 IdealLoopTree *use_loop = get_loop(region);
193 if (!new_loop->is_member(use_loop) &&
194 (old_loop == NULL || !new_loop->is_member(old_loop))) {
195 // Take early control, later control will be recalculated
196 // during next iteration of loop optimizations.
197 new_ctrl = get_early_ctrl(x);
198 new_loop = get_loop(new_ctrl);
199 }
200 // Set new location
201 set_ctrl(x, new_ctrl);
202 // If changing loop bodies, see if we need to collect into new body
203 if (old_loop != new_loop) {
204 if (old_loop && !old_loop->_child)
205 old_loop->_body.yank(x);
206 if (!new_loop->_child)
207 new_loop->_body.push(x); // Collect body info
208 }
209 }
210
211 return phi;
212 }
213
214 //------------------------------dominated_by------------------------------------
215 // Replace the dominated test with an obvious true or false. Place it on the
216 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
217 // live path up to the dominating control.
218 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
219 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
220
221 // prevdom is the dominating projection of the dominating test.
222 assert( iff->is_If(), "" );
223 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
224 int pop = prevdom->Opcode();
225 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
226 if (flip) {
227 if (pop == Op_IfTrue)
228 pop = Op_IfFalse;
229 else
230 pop = Op_IfTrue;
231 }
232 // 'con' is set to true or false to kill the dominated test.
233 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
234 set_ctrl(con, C->root()); // Constant gets a new use
235 // Hack the dominated test
236 _igvn.replace_input_of(iff, 1, con);
237
238 // If I dont have a reachable TRUE and FALSE path following the IfNode then
239 // I can assume this path reaches an infinite loop. In this case it's not
240 // important to optimize the data Nodes - either the whole compilation will
241 // be tossed or this path (and all data Nodes) will go dead.
242 if (iff->outcnt() != 2) return;
243
244 // Make control-dependent data Nodes on the live path (path that will remain
245 // once the dominated IF is removed) become control-dependent on the
246 // dominating projection.
247 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
248
249 // Loop predicates may have depending checks which should not
250 // be skipped. For example, range check predicate has two checks
251 // for lower and upper bounds.
252 if (dp == NULL)
253 return;
254
255 ProjNode* dp_proj = dp->as_Proj();
256 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
257 if (exclude_loop_predicate &&
258 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
259 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
260 // If this is a range check (IfNode::is_range_check), do not
261 // reorder because Compile::allow_range_check_smearing might have
262 // changed the check.
263 return; // Let IGVN transformation change control dependence.
264 }
265
266 IdealLoopTree *old_loop = get_loop(dp);
267
268 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
269 Node* cd = dp->fast_out(i); // Control-dependent node
270 if (cd->depends_only_on_test()) {
271 assert(cd->in(0) == dp, "");
272 _igvn.replace_input_of(cd, 0, prevdom);
273 set_early_ctrl(cd);
274 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
275 if (old_loop != new_loop) {
276 if (!old_loop->_child) old_loop->_body.yank(cd);
277 if (!new_loop->_child) new_loop->_body.push(cd);
278 }
279 --i;
280 --imax;
281 }
282 }
283 }
284
285 //------------------------------has_local_phi_input----------------------------
286 // Return TRUE if 'n' has Phi inputs from its local block and no other
287 // block-local inputs (all non-local-phi inputs come from earlier blocks)
288 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
289 Node *n_ctrl = get_ctrl(n);
290 // See if some inputs come from a Phi in this block, or from before
291 // this block.
292 uint i;
293 for( i = 1; i < n->req(); i++ ) {
294 Node *phi = n->in(i);
295 if( phi->is_Phi() && phi->in(0) == n_ctrl )
296 break;
297 }
298 if( i >= n->req() )
299 return NULL; // No Phi inputs; nowhere to clone thru
300
301 // Check for inputs created between 'n' and the Phi input. These
302 // must split as well; they have already been given the chance
303 // (courtesy of a post-order visit) and since they did not we must
304 // recover the 'cost' of splitting them by being very profitable
305 // when splitting 'n'. Since this is unlikely we simply give up.
306 for( i = 1; i < n->req(); i++ ) {
307 Node *m = n->in(i);
308 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
309 // We allow the special case of AddP's with no local inputs.
310 // This allows us to split-up address expressions.
311 if (m->is_AddP() &&
312 get_ctrl(m->in(2)) != n_ctrl &&
313 get_ctrl(m->in(3)) != n_ctrl) {
314 // Move the AddP up to dominating point
315 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
316 continue;
317 }
318 return NULL;
319 }
320 }
321
322 return n_ctrl;
323 }
324
325 //------------------------------remix_address_expressions----------------------
326 // Rework addressing expressions to get the most loop-invariant stuff
327 // moved out. We'd like to do all associative operators, but it's especially
328 // important (common) to do address expressions.
329 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
330 if (!has_ctrl(n)) return NULL;
331 Node *n_ctrl = get_ctrl(n);
332 IdealLoopTree *n_loop = get_loop(n_ctrl);
333
334 // See if 'n' mixes loop-varying and loop-invariant inputs and
335 // itself is loop-varying.
336
337 // Only interested in binary ops (and AddP)
338 if( n->req() < 3 || n->req() > 4 ) return NULL;
339
340 Node *n1_ctrl = get_ctrl(n->in( 1));
341 Node *n2_ctrl = get_ctrl(n->in( 2));
342 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
343 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
344 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
345 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
346
347 // Does one of my inputs spin in a tighter loop than self?
348 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
349 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
350 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
351 return NULL; // Leave well enough alone
352
353 // Is at least one of my inputs loop-invariant?
354 if( n1_loop == n_loop &&
355 n2_loop == n_loop &&
356 n3_loop == n_loop )
357 return NULL; // No loop-invariant inputs
358
359
360 int n_op = n->Opcode();
361
362 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
363 if( n_op == Op_LShiftI ) {
364 // Scale is loop invariant
365 Node *scale = n->in(2);
366 Node *scale_ctrl = get_ctrl(scale);
367 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
368 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
369 return NULL;
370 const TypeInt *scale_t = scale->bottom_type()->isa_int();
371 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
372 return NULL; // Dont bother with byte/short masking
373 // Add must vary with loop (else shift would be loop-invariant)
374 Node *add = n->in(1);
375 Node *add_ctrl = get_ctrl(add);
376 IdealLoopTree *add_loop = get_loop(add_ctrl);
377 //assert( n_loop == add_loop, "" );
378 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
379
380 // Convert I-V into I+ (0-V); same for V-I
381 if( add->Opcode() == Op_SubI &&
382 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
383 Node *zero = _igvn.intcon(0);
384 set_ctrl(zero, C->root());
385 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
386 register_new_node( neg, get_ctrl(add->in(2) ) );
387 add = new AddINode( add->in(1), neg );
388 register_new_node( add, add_ctrl );
389 }
390 if( add->Opcode() != Op_AddI ) return NULL;
391 // See if one add input is loop invariant
392 Node *add_var = add->in(1);
393 Node *add_var_ctrl = get_ctrl(add_var);
394 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
395 Node *add_invar = add->in(2);
396 Node *add_invar_ctrl = get_ctrl(add_invar);
397 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
398 if( add_var_loop == n_loop ) {
399 } else if( add_invar_loop == n_loop ) {
400 // Swap to find the invariant part
401 add_invar = add_var;
402 add_invar_ctrl = add_var_ctrl;
403 add_invar_loop = add_var_loop;
404 add_var = add->in(2);
405 Node *add_var_ctrl = get_ctrl(add_var);
406 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
407 } else // Else neither input is loop invariant
408 return NULL;
409 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
410 return NULL; // No invariant part of the add?
411
412 // Yes! Reshape address expression!
413 Node *inv_scale = new LShiftINode( add_invar, scale );
414 Node *inv_scale_ctrl =
415 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
416 add_invar_ctrl : scale_ctrl;
417 register_new_node( inv_scale, inv_scale_ctrl );
418 Node *var_scale = new LShiftINode( add_var, scale );
419 register_new_node( var_scale, n_ctrl );
420 Node *var_add = new AddINode( var_scale, inv_scale );
421 register_new_node( var_add, n_ctrl );
422 _igvn.replace_node( n, var_add );
423 return var_add;
424 }
425
426 // Replace (I+V) with (V+I)
427 if( n_op == Op_AddI ||
428 n_op == Op_AddL ||
429 n_op == Op_AddF ||
430 n_op == Op_AddD ||
431 n_op == Op_MulI ||
432 n_op == Op_MulL ||
433 n_op == Op_MulF ||
434 n_op == Op_MulD ) {
435 if( n2_loop == n_loop ) {
436 assert( n1_loop != n_loop, "" );
437 n->swap_edges(1, 2);
438 }
439 }
440
441 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
442 // but not if I2 is a constant.
443 if( n_op == Op_AddP ) {
444 if( n2_loop == n_loop && n3_loop != n_loop ) {
445 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
446 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
447 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
448 IdealLoopTree *n22loop = get_loop( n22_ctrl );
449 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
450 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
451 n23_loop == n_loop ) {
452 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
453 // Stuff new AddP in the loop preheader
454 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
455 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
456 register_new_node( add2, n_ctrl );
457 _igvn.replace_node( n, add2 );
458 return add2;
459 }
460 }
461 }
462
463 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
464 if (n2_loop != n_loop && n3_loop == n_loop) {
465 if (n->in(3)->Opcode() == Op_AddX) {
466 Node *V = n->in(3)->in(1);
467 Node *I = n->in(3)->in(2);
468 if (is_member(n_loop,get_ctrl(V))) {
469 } else {
470 Node *tmp = V; V = I; I = tmp;
471 }
472 if (!is_member(n_loop,get_ctrl(I))) {
473 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
474 // Stuff new AddP in the loop preheader
475 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
476 Node *add2 = new AddPNode(n->in(1), add1, V);
477 register_new_node(add2, n_ctrl);
478 _igvn.replace_node(n, add2);
479 return add2;
480 }
481 }
482 }
483 }
484
485 return NULL;
486 }
487
488 //------------------------------conditional_move-------------------------------
489 // Attempt to replace a Phi with a conditional move. We have some pretty
490 // strict profitability requirements. All Phis at the merge point must
491 // be converted, so we can remove the control flow. We need to limit the
492 // number of c-moves to a small handful. All code that was in the side-arms
493 // of the CFG diamond is now speculatively executed. This code has to be
494 // "cheap enough". We are pretty much limited to CFG diamonds that merge
495 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
496 Node *PhaseIdealLoop::conditional_move( Node *region ) {
497
498 assert(region->is_Region(), "sanity check");
499 if (region->req() != 3) return NULL;
500
501 // Check for CFG diamond
502 Node *lp = region->in(1);
503 Node *rp = region->in(2);
504 if (!lp || !rp) return NULL;
505 Node *lp_c = lp->in(0);
506 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
507 IfNode *iff = lp_c->as_If();
508
509 // Check for ops pinned in an arm of the diamond.
510 // Can't remove the control flow in this case
511 if (lp->outcnt() > 1) return NULL;
512 if (rp->outcnt() > 1) return NULL;
513
514 IdealLoopTree* r_loop = get_loop(region);
515 assert(r_loop == get_loop(iff), "sanity");
516 // Always convert to CMOVE if all results are used only outside this loop.
517 bool used_inside_loop = (r_loop == _ltree_root);
518
519 // Check profitability
520 int cost = 0;
521 int phis = 0;
522 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
523 Node *out = region->fast_out(i);
524 if (!out->is_Phi()) continue; // Ignore other control edges, etc
525 phis++;
526 PhiNode* phi = out->as_Phi();
527 BasicType bt = phi->type()->basic_type();
528 switch (bt) {
529 case T_DOUBLE:
530 if (C->use_cmove()) {
531 continue; //TODO: maybe we want to add some cost
532 }
533 case T_FLOAT: {
534 cost += Matcher::float_cmove_cost(); // Could be very expensive
535 break;
536 }
537 case T_LONG: {
538 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
539 }
540 case T_INT: // These all CMOV fine
541 case T_ADDRESS: { // (RawPtr)
542 cost++;
543 break;
544 }
545 case T_NARROWOOP: // Fall through
546 case T_OBJECT: { // Base oops are OK, but not derived oops
547 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
548 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
549 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
550 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
551 // have a Phi for the base here that we convert to a CMOVE all is well
552 // and good. But if the base is dead, we'll not make a CMOVE. Later
553 // the allocator will have to produce a base by creating a CMOVE of the
554 // relevant bases. This puts the allocator in the business of
555 // manufacturing expensive instructions, generally a bad plan.
556 // Just Say No to Conditionally-Moved Derived Pointers.
557 if (tp && tp->offset() != 0)
558 return NULL;
559 cost++;
560 break;
561 }
562 default:
563 return NULL; // In particular, can't do memory or I/O
564 }
565 // Add in cost any speculative ops
566 for (uint j = 1; j < region->req(); j++) {
567 Node *proj = region->in(j);
568 Node *inp = phi->in(j);
569 if (get_ctrl(inp) == proj) { // Found local op
570 cost++;
571 // Check for a chain of dependent ops; these will all become
572 // speculative in a CMOV.
573 for (uint k = 1; k < inp->req(); k++)
574 if (get_ctrl(inp->in(k)) == proj)
575 cost += ConditionalMoveLimit; // Too much speculative goo
576 }
577 }
578 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
579 // This will likely Split-If, a higher-payoff operation.
580 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
581 Node* use = phi->fast_out(k);
582 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
583 cost += ConditionalMoveLimit;
584 // Is there a use inside the loop?
585 // Note: check only basic types since CMoveP is pinned.
586 if (!used_inside_loop && is_java_primitive(bt)) {
587 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
588 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
589 used_inside_loop = true;
590 }
591 }
592 }
593 }//for
594 Node* bol = iff->in(1);
595 assert(bol->Opcode() == Op_Bool, "");
596 int cmp_op = bol->in(1)->Opcode();
597 // It is expensive to generate flags from a float compare.
598 // Avoid duplicated float compare.
599 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
600
601 float infrequent_prob = PROB_UNLIKELY_MAG(3);
602 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
603 if (used_inside_loop) {
604 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
605
606 // BlockLayoutByFrequency optimization moves infrequent branch
607 // from hot path. No point in CMOV'ing in such case (110 is used
608 // instead of 100 to take into account not exactness of float value).
609 if (BlockLayoutByFrequency) {
610 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
611 }
612 }
613 // Check for highly predictable branch. No point in CMOV'ing if
614 // we are going to predict accurately all the time.
615 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
616 else if (iff->_prob < infrequent_prob ||
617 iff->_prob > (1.0f - infrequent_prob))
618 return NULL;
619
620 // --------------
621 // Now replace all Phis with CMOV's
622 Node *cmov_ctrl = iff->in(0);
623 uint flip = (lp->Opcode() == Op_IfTrue);
624 while (1) {
625 PhiNode* phi = NULL;
626 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
627 Node *out = region->fast_out(i);
628 if (out->is_Phi()) {
629 phi = out->as_Phi();
630 break;
631 }
632 }
633 if (phi == NULL) break;
634 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
635 // Move speculative ops
636 for (uint j = 1; j < region->req(); j++) {
637 Node *proj = region->in(j);
638 Node *inp = phi->in(j);
639 if (get_ctrl(inp) == proj) { // Found local op
640 #ifndef PRODUCT
641 if (PrintOpto && VerifyLoopOptimizations) {
642 tty->print(" speculate: ");
643 inp->dump();
644 }
645 #endif
646 set_ctrl(inp, cmov_ctrl);
647 }
648 }
649 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
650 register_new_node( cmov, cmov_ctrl );
651 _igvn.replace_node( phi, cmov );
652 #ifndef PRODUCT
653 if (TraceLoopOpts) {
654 tty->print("CMOV ");
655 r_loop->dump_head();
656 if (Verbose) {
657 bol->in(1)->dump(1);
658 cmov->dump(1);
659 }
660 }
661 if (VerifyLoopOptimizations) verify();
662 #endif
663 }
664
665 // The useless CFG diamond will fold up later; see the optimization in
666 // RegionNode::Ideal.
667 _igvn._worklist.push(region);
668
669 return iff->in(1);
670 }
671
672 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
673 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
674 Node* u = m->fast_out(i);
675 if (u->is_CFG()) {
676 if (u->Opcode() == Op_NeverBranch) {
677 u = ((NeverBranchNode*)u)->proj_out(0);
678 enqueue_cfg_uses(u, wq);
679 } else {
680 wq.push(u);
681 }
682 }
683 }
684 }
685
686 // Try moving a store out of a loop, right before the loop
687 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
688 // Store has to be first in the loop body
689 IdealLoopTree *n_loop = get_loop(n_ctrl);
690 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
691 Node* address = n->in(MemNode::Address);
692 Node* value = n->in(MemNode::ValueIn);
693 Node* mem = n->in(MemNode::Memory);
694 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
695 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
696
697 // - address and value must be loop invariant
698 // - memory must be a memory Phi for the loop
699 // - Store must be the only store on this memory slice in the
700 // loop: if there's another store following this one then value
701 // written at iteration i by the second store could be overwritten
702 // at iteration i+n by the first store: it's not safe to move the
703 // first store out of the loop
704 // - nothing must observe the memory Phi: it guarantees no read
705 // before the store, we are also guaranteed the store post
706 // dominates the loop head (ignoring a possible early
707 // exit). Otherwise there would be extra Phi involved between the
708 // loop's Phi and the store.
709 // - there must be no early exit from the loop before the Store
710 // (such an exit most of the time would be an extra use of the
711 // memory Phi but sometimes is a bottom memory Phi that takes the
712 // store as input).
713
714 if (!n_loop->is_member(address_loop) &&
715 !n_loop->is_member(value_loop) &&
716 mem->is_Phi() && mem->in(0) == n_loop->_head &&
717 mem->outcnt() == 1 &&
718 mem->in(LoopNode::LoopBackControl) == n) {
719
720 assert(n_loop->_tail != NULL, "need a tail");
721 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
722
723 // Verify that there's no early exit of the loop before the store.
724 bool ctrl_ok = false;
725 {
726 // Follow control from loop head until n, we exit the loop or
727 // we reach the tail
728 ResourceMark rm;
729 Unique_Node_List wq;
730 wq.push(n_loop->_head);
731
732 for (uint next = 0; next < wq.size(); ++next) {
733 Node *m = wq.at(next);
734 if (m == n->in(0)) {
735 ctrl_ok = true;
736 continue;
737 }
738 assert(!has_ctrl(m), "should be CFG");
739 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
740 ctrl_ok = false;
741 break;
742 }
743 enqueue_cfg_uses(m, wq);
744 if (wq.size() > 10) {
745 ctrl_ok = false;
746 break;
747 }
748 }
749 }
750 if (ctrl_ok) {
751 // move the Store
752 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
753 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
754 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
755 // Disconnect the phi now. An empty phi can confuse other
756 // optimizations in this pass of loop opts.
757 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
758 n_loop->_body.yank(mem);
759
760 IdealLoopTree* new_loop = get_loop(n->in(0));
761 set_ctrl_and_loop(n, n->in(0));
762
763 return n;
764 }
765 }
766 }
767 return NULL;
768 }
769
770 // Try moving a store out of a loop, right after the loop
771 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
772 if (n->is_Store() && n->in(0) != NULL) {
773 Node *n_ctrl = get_ctrl(n);
774 IdealLoopTree *n_loop = get_loop(n_ctrl);
775 // Store must be in a loop
776 if (n_loop != _ltree_root && !n_loop->_irreducible) {
777 Node* address = n->in(MemNode::Address);
778 Node* value = n->in(MemNode::ValueIn);
779 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
780 // address must be loop invariant
781 if (!n_loop->is_member(address_loop)) {
782 // Store must be last on this memory slice in the loop and
783 // nothing in the loop must observe it
784 Node* phi = NULL;
785 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
786 Node* u = n->fast_out(i);
787 if (has_ctrl(u)) { // control use?
788 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
789 if (!n_loop->is_member(u_loop)) {
790 continue;
791 }
792 if (u->is_Phi() && u->in(0) == n_loop->_head) {
793 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
794 // multiple phis on the same slice are possible
795 if (phi != NULL) {
796 return;
797 }
798 phi = u;
799 continue;
800 }
801 }
802 return;
803 }
804 if (phi != NULL) {
805 // Nothing in the loop before the store (next iteration)
806 // must observe the stored value
807 bool mem_ok = true;
808 {
809 ResourceMark rm;
810 Unique_Node_List wq;
811 wq.push(phi);
812 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
813 Node *m = wq.at(next);
814 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
815 Node* u = m->fast_out(i);
816 if (u->is_Store() || u->is_Phi()) {
817 if (u != n) {
818 wq.push(u);
819 mem_ok = (wq.size() <= 10);
820 }
821 } else {
822 mem_ok = false;
823 break;
824 }
825 }
826 }
827 }
828 if (mem_ok) {
829 // Move the Store out of the loop creating clones along
830 // all paths out of the loop that observe the stored value
831 _igvn.rehash_node_delayed(phi);
832 int count = phi->replace_edge(n, n->in(MemNode::Memory));
833 assert(count > 0, "inconsistent phi");
834 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
835 Node* u = n->fast_out(i);
836 Node* c = get_ctrl(u);
837
838 if (u->is_Phi()) {
839 c = u->in(0)->in(u->find_edge(n));
840 }
841 IdealLoopTree *u_loop = get_loop(c);
842 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
843 while(true) {
844 Node* next_c = find_non_split_ctrl(idom(c));
845 if (n_loop->is_member(get_loop(next_c))) {
846 break;
847 }
848 c = next_c;
849 }
850
851 Node* st = n->clone();
852 st->set_req(0, c);
853 _igvn.register_new_node_with_optimizer(st);
854
855 set_ctrl(st, c);
856 IdealLoopTree* new_loop = get_loop(c);
857 assert(new_loop != n_loop, "should be moved out of loop");
858 if (new_loop->_child == NULL) new_loop->_body.push(st);
859
860 _igvn.replace_input_of(u, u->find_edge(n), st);
861 --imax;
862 --i;
863 }
864
865
866 assert(n->outcnt() == 0, "all uses should be gone");
867 _igvn.replace_input_of(n, MemNode::Memory, C->top());
868 // Disconnect the phi now. An empty phi can confuse other
869 // optimizations in this pass of loop opts..
870 if (phi->in(LoopNode::LoopBackControl) == phi) {
871 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
872 n_loop->_body.yank(phi);
873 }
874 }
875 }
876 }
877 }
878 }
879 }
880
881 //------------------------------split_if_with_blocks_pre-----------------------
882 // Do the real work in a non-recursive function. Data nodes want to be
883 // cloned in the pre-order so they can feed each other nicely.
884 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
885 // Cloning these guys is unlikely to win
886 int n_op = n->Opcode();
887 if( n_op == Op_MergeMem ) return n;
888 if( n->is_Proj() ) return n;
889 // Do not clone-up CmpFXXX variations, as these are always
890 // followed by a CmpI
891 if( n->is_Cmp() ) return n;
892 // Attempt to use a conditional move instead of a phi/branch
893 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
894 Node *cmov = conditional_move( n );
895 if( cmov ) return cmov;
896 }
897 if( n->is_CFG() || n->is_LoadStore() )
898 return n;
899 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
900 n_op == Op_Opaque2 ) {
901 if( !C->major_progress() ) // If chance of no more loop opts...
902 _igvn._worklist.push(n); // maybe we'll remove them
903 return n;
904 }
905
906 if( n->is_Con() ) return n; // No cloning for Con nodes
907
908 Node *n_ctrl = get_ctrl(n);
909 if( !n_ctrl ) return n; // Dead node
910
911 Node* res = try_move_store_before_loop(n, n_ctrl);
912 if (res != NULL) {
913 return n;
914 }
915
916 // Attempt to remix address expressions for loop invariants
917 Node *m = remix_address_expressions( n );
918 if( m ) return m;
919
920 if (n->is_ConstraintCast()) {
921 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(this);
922 if (dom_cast != NULL) {
923 _igvn.replace_node(n, dom_cast);
924 return dom_cast;
925 }
926 }
927
928 // Determine if the Node has inputs from some local Phi.
929 // Returns the block to clone thru.
930 Node *n_blk = has_local_phi_input( n );
931 if( !n_blk ) return n;
932
933 // Do not clone the trip counter through on a CountedLoop
934 // (messes up the canonical shape).
935 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
936
937 // Check for having no control input; not pinned. Allow
938 // dominating control.
939 if (n->in(0)) {
940 Node *dom = idom(n_blk);
941 if (dom_lca(n->in(0), dom) != n->in(0)) {
942 return n;
943 }
944 }
945 // Policy: when is it profitable. You must get more wins than
946 // policy before it is considered profitable. Policy is usually 0,
947 // so 1 win is considered profitable. Big merges will require big
948 // cloning, so get a larger policy.
949 int policy = n_blk->req() >> 2;
950
951 // If the loop is a candidate for range check elimination,
952 // delay splitting through it's phi until a later loop optimization
953 if (n_blk->is_CountedLoop()) {
954 IdealLoopTree *lp = get_loop(n_blk);
955 if (lp && lp->_rce_candidate) {
956 return n;
957 }
958 }
959
960 // Use same limit as split_if_with_blocks_post
961 if( C->live_nodes() > 35000 ) return n; // Method too big
962
963 // Split 'n' through the merge point if it is profitable
964 Node *phi = split_thru_phi( n, n_blk, policy );
965 if (!phi) return n;
966
967 // Found a Phi to split thru!
968 // Replace 'n' with the new phi
969 _igvn.replace_node( n, phi );
970 // Moved a load around the loop, 'en-registering' something.
971 if (n_blk->is_Loop() && n->is_Load() &&
972 !phi->in(LoopNode::LoopBackControl)->is_Load())
973 C->set_major_progress();
974
975 return phi;
976 }
977
978 static bool merge_point_too_heavy(Compile* C, Node* region) {
979 // Bail out if the region and its phis have too many users.
980 int weight = 0;
981 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
982 weight += region->fast_out(i)->outcnt();
983 }
984 int nodes_left = C->max_node_limit() - C->live_nodes();
985 if (weight * 8 > nodes_left) {
986 if (PrintOpto) {
987 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
988 }
989 return true;
990 } else {
991 return false;
992 }
993 }
994
995 static bool merge_point_safe(Node* region) {
996 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
997 // having a PhiNode input. This sidesteps the dangerous case where the split
998 // ConvI2LNode may become TOP if the input Value() does not
999 // overlap the ConvI2L range, leaving a node which may not dominate its
1000 // uses.
1001 // A better fix for this problem can be found in the BugTraq entry, but
1002 // expediency for Mantis demands this hack.
1003 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1004 // split_if_with_blocks from splitting a block because we could not move around
1005 // the FastLockNode.
1006 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1007 Node* n = region->fast_out(i);
1008 if (n->is_Phi()) {
1009 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1010 Node* m = n->fast_out(j);
1011 if (m->is_FastLock())
1012 return false;
1013 #ifdef _LP64
1014 if (m->Opcode() == Op_ConvI2L)
1015 return false;
1016 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1017 return false;
1018 }
1019 #endif
1020 }
1021 }
1022 }
1023 return true;
1024 }
1025
1026
1027 //------------------------------place_near_use---------------------------------
1028 // Place some computation next to use but not inside inner loops.
1029 // For inner loop uses move it to the preheader area.
1030 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1031 IdealLoopTree *u_loop = get_loop( useblock );
1032 return (u_loop->_irreducible || u_loop->_child)
1033 ? useblock
1034 : u_loop->_head->in(LoopNode::EntryControl);
1035 }
1036
1037
1038 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1039 if (!n->is_If()) {
1040 return false;
1041 }
1042 if (!n->in(0)->is_Region()) {
1043 return false;
1044 }
1045 Node* region = n->in(0);
1046 Node* dom = idom(region);
1047 if (!dom->is_If() || dom->in(1) != n->in(1)) {
1048 return false;
1049 }
1050 IfNode* dom_if = dom->as_If();
1051 Node* proj_true = dom_if->proj_out(1);
1052 Node* proj_false = dom_if->proj_out(0);
1053
1054 for (uint i = 1; i < region->req(); i++) {
1055 if (is_dominator(proj_true, region->in(i))) {
1056 continue;
1057 }
1058 if (is_dominator(proj_false, region->in(i))) {
1059 continue;
1060 }
1061 return false;
1062 }
1063
1064 return true;
1065 }
1066
1067 bool PhaseIdealLoop::can_split_if(Node *n_ctrl) {
1068 if (C->live_nodes() > 35000) {
1069 return false; // Method too big
1070 }
1071
1072 // Do not do 'split-if' if irreducible loops are present.
1073 if (_has_irreducible_loops) {
1074 return false;
1075 }
1076
1077 if (merge_point_too_heavy(C, n_ctrl)) {
1078 return false;
1079 }
1080
1081 // Do not do 'split-if' if some paths are dead. First do dead code
1082 // elimination and then see if its still profitable.
1083 for (uint i = 1; i < n_ctrl->req(); i++) {
1084 if (n_ctrl->in(i) == C->top()) {
1085 return false;
1086 }
1087 }
1088
1089 // If trying to do a 'Split-If' at the loop head, it is only
1090 // profitable if the cmp folds up on BOTH paths. Otherwise we
1091 // risk peeling a loop forever.
1092
1093 // CNC - Disabled for now. Requires careful handling of loop
1094 // body selection for the cloned code. Also, make sure we check
1095 // for any input path not being in the same loop as n_ctrl. For
1096 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1097 // because the alternative loop entry points won't be converted
1098 // into LoopNodes.
1099 IdealLoopTree *n_loop = get_loop(n_ctrl);
1100 for (uint j = 1; j < n_ctrl->req(); j++) {
1101 if (get_loop(n_ctrl->in(j)) != n_loop) {
1102 return false;
1103 }
1104 }
1105
1106 // Check for safety of the merge point.
1107 if (!merge_point_safe(n_ctrl)) {
1108 return false;
1109 }
1110
1111 return true;
1112 }
1113
1114 //------------------------------split_if_with_blocks_post----------------------
1115 // Do the real work in a non-recursive function. CFG hackery wants to be
1116 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1117 // info.
1118 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1119
1120 // Cloning Cmp through Phi's involves the split-if transform.
1121 // FastLock is not used by an If
1122 if (n->is_Cmp() && !n->is_FastLock()) {
1123 Node *n_ctrl = get_ctrl(n);
1124 // Determine if the Node has inputs from some local Phi.
1125 // Returns the block to clone thru.
1126 Node *n_blk = has_local_phi_input(n);
1127 if (n_blk != n_ctrl) {
1128 return;
1129 }
1130
1131 if (!can_split_if(n_ctrl)) {
1132 return;
1133 }
1134
1135 if (n->outcnt() != 1) {
1136 return; // Multiple bool's from 1 compare?
1137 }
1138 Node *bol = n->unique_out();
1139 assert(bol->is_Bool(), "expect a bool here");
1140 if (bol->outcnt() != 1) {
1141 return;// Multiple branches from 1 compare?
1142 }
1143 Node *iff = bol->unique_out();
1144
1145 // Check some safety conditions
1146 if (iff->is_If()) { // Classic split-if?
1147 if (iff->in(0) != n_ctrl) {
1148 return; // Compare must be in same blk as if
1149 }
1150 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1151 // Can't split CMove with different control edge.
1152 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1153 return;
1154 }
1155 if (get_ctrl(iff->in(2)) == n_ctrl ||
1156 get_ctrl(iff->in(3)) == n_ctrl) {
1157 return; // Inputs not yet split-up
1158 }
1159 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1160 return; // Loop-invar test gates loop-varying CMOVE
1161 }
1162 } else {
1163 return; // some other kind of node, such as an Allocate
1164 }
1165
1166 // When is split-if profitable? Every 'win' on means some control flow
1167 // goes dead, so it's almost always a win.
1168 int policy = 0;
1169 // Split compare 'n' through the merge point if it is profitable
1170 Node *phi = split_thru_phi( n, n_ctrl, policy);
1171 if (!phi) {
1172 return;
1173 }
1174
1175 // Found a Phi to split thru!
1176 // Replace 'n' with the new phi
1177 _igvn.replace_node(n, phi);
1178
1179 // Now split the bool up thru the phi
1180 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1181 guarantee(bolphi != NULL, "null boolean phi node");
1182
1183 _igvn.replace_node(bol, bolphi);
1184 assert(iff->in(1) == bolphi, "");
1185
1186 if (bolphi->Value(&_igvn)->singleton()) {
1187 return;
1188 }
1189
1190 // Conditional-move? Must split up now
1191 if (!iff->is_If()) {
1192 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1193 _igvn.replace_node(iff, cmovphi);
1194 return;
1195 }
1196
1197 // Now split the IF
1198 do_split_if(iff);
1199 return;
1200 }
1201
1202 // Two identical ifs back to back can be merged
1203 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1204 Node *n_ctrl = n->in(0);
1205 PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1206 IfNode* dom_if = idom(n_ctrl)->as_If();
1207 Node* proj_true = dom_if->proj_out(1);
1208 Node* proj_false = dom_if->proj_out(0);
1209 Node* con_true = _igvn.makecon(TypeInt::ONE);
1210 Node* con_false = _igvn.makecon(TypeInt::ZERO);
1211
1212 for (uint i = 1; i < n_ctrl->req(); i++) {
1213 if (is_dominator(proj_true, n_ctrl->in(i))) {
1214 bolphi->init_req(i, con_true);
1215 } else {
1216 assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1217 bolphi->init_req(i, con_false);
1218 }
1219 }
1220 register_new_node(bolphi, n_ctrl);
1221 _igvn.replace_input_of(n, 1, bolphi);
1222
1223 // Now split the IF
1224 do_split_if(n);
1225 return;
1226 }
1227
1228 // Check for an IF ready to split; one that has its
1229 // condition codes input coming from a Phi at the block start.
1230 int n_op = n->Opcode();
1231
1232 // Check for an IF being dominated by another IF same test
1233 if (n_op == Op_If ||
1234 n_op == Op_RangeCheck) {
1235 Node *bol = n->in(1);
1236 uint max = bol->outcnt();
1237 // Check for same test used more than once?
1238 if (max > 1 && bol->is_Bool()) {
1239 // Search up IDOMs to see if this IF is dominated.
1240 Node *cutoff = get_ctrl(bol);
1241
1242 // Now search up IDOMs till cutoff, looking for a dominating test
1243 Node *prevdom = n;
1244 Node *dom = idom(prevdom);
1245 while (dom != cutoff) {
1246 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1247 // Replace the dominated test with an obvious true or false.
1248 // Place it on the IGVN worklist for later cleanup.
1249 C->set_major_progress();
1250 dominated_by(prevdom, n, false, true);
1251 #ifndef PRODUCT
1252 if( VerifyLoopOptimizations ) verify();
1253 #endif
1254 return;
1255 }
1256 prevdom = dom;
1257 dom = idom(prevdom);
1258 }
1259 }
1260 }
1261
1262 // See if a shared loop-varying computation has no loop-varying uses.
1263 // Happens if something is only used for JVM state in uncommon trap exits,
1264 // like various versions of induction variable+offset. Clone the
1265 // computation per usage to allow it to sink out of the loop.
1266 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1267 Node *n_ctrl = get_ctrl(n);
1268 IdealLoopTree *n_loop = get_loop(n_ctrl);
1269 if( n_loop != _ltree_root ) {
1270 DUIterator_Fast imax, i = n->fast_outs(imax);
1271 for (; i < imax; i++) {
1272 Node* u = n->fast_out(i);
1273 if( !has_ctrl(u) ) break; // Found control user
1274 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1275 if( u_loop == n_loop ) break; // Found loop-varying use
1276 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1277 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1278 }
1279 bool did_break = (i < imax); // Did we break out of the previous loop?
1280 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1281 Node *late_load_ctrl = NULL;
1282 if (n->is_Load()) {
1283 // If n is a load, get and save the result from get_late_ctrl(),
1284 // to be later used in calculating the control for n's clones.
1285 clear_dom_lca_tags();
1286 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1287 }
1288 // If n is a load, and the late control is the same as the current
1289 // control, then the cloning of n is a pointless exercise, because
1290 // GVN will ensure that we end up where we started.
1291 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1292 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1293 Node *u = n->last_out(j); // Clone private computation per use
1294 _igvn.rehash_node_delayed(u);
1295 Node *x = n->clone(); // Clone computation
1296 Node *x_ctrl = NULL;
1297 if( u->is_Phi() ) {
1298 // Replace all uses of normal nodes. Replace Phi uses
1299 // individually, so the separate Nodes can sink down
1300 // different paths.
1301 uint k = 1;
1302 while( u->in(k) != n ) k++;
1303 u->set_req( k, x );
1304 // x goes next to Phi input path
1305 x_ctrl = u->in(0)->in(k);
1306 --j;
1307 } else { // Normal use
1308 // Replace all uses
1309 for( uint k = 0; k < u->req(); k++ ) {
1310 if( u->in(k) == n ) {
1311 u->set_req( k, x );
1312 --j;
1313 }
1314 }
1315 x_ctrl = get_ctrl(u);
1316 }
1317
1318 // Find control for 'x' next to use but not inside inner loops.
1319 // For inner loop uses get the preheader area.
1320 x_ctrl = place_near_use(x_ctrl);
1321
1322 if (n->is_Load()) {
1323 // For loads, add a control edge to a CFG node outside of the loop
1324 // to force them to not combine and return back inside the loop
1325 // during GVN optimization (4641526).
1326 //
1327 // Because we are setting the actual control input, factor in
1328 // the result from get_late_ctrl() so we respect any
1329 // anti-dependences. (6233005).
1330 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1331
1332 // Don't allow the control input to be a CFG splitting node.
1333 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1334 // should only have IfTrueNode and IfFalseNode (4985384).
1335 x_ctrl = find_non_split_ctrl(x_ctrl);
1336 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1337
1338 x->set_req(0, x_ctrl);
1339 }
1340 register_new_node(x, x_ctrl);
1341
1342 // Some institutional knowledge is needed here: 'x' is
1343 // yanked because if the optimizer runs GVN on it all the
1344 // cloned x's will common up and undo this optimization and
1345 // be forced back in the loop. This is annoying because it
1346 // makes +VerifyOpto report false-positives on progress. I
1347 // tried setting control edges on the x's to force them to
1348 // not combine, but the matching gets worried when it tries
1349 // to fold a StoreP and an AddP together (as part of an
1350 // address expression) and the AddP and StoreP have
1351 // different controls.
1352 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1353 }
1354 _igvn.remove_dead_node(n);
1355 }
1356 }
1357 }
1358 }
1359
1360 try_move_store_after_loop(n);
1361
1362 // Check for Opaque2's who's loop has disappeared - who's input is in the
1363 // same loop nest as their output. Remove 'em, they are no longer useful.
1364 if( n_op == Op_Opaque2 &&
1365 n->in(1) != NULL &&
1366 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1367 _igvn.replace_node( n, n->in(1) );
1368 }
1369 }
1370
1371 //------------------------------split_if_with_blocks---------------------------
1372 // Check for aggressive application of 'split-if' optimization,
1373 // using basic block level info.
1374 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1375 Node *n = C->root();
1376 visited.set(n->_idx); // first, mark node as visited
1377 // Do pre-visit work for root
1378 n = split_if_with_blocks_pre( n );
1379 uint cnt = n->outcnt();
1380 uint i = 0;
1381 while (true) {
1382 // Visit all children
1383 if (i < cnt) {
1384 Node* use = n->raw_out(i);
1385 ++i;
1386 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1387 // Now do pre-visit work for this use
1388 use = split_if_with_blocks_pre( use );
1389 nstack.push(n, i); // Save parent and next use's index.
1390 n = use; // Process all children of current use.
1391 cnt = use->outcnt();
1392 i = 0;
1393 }
1394 }
1395 else {
1396 // All of n's children have been processed, complete post-processing.
1397 if (cnt != 0 && !n->is_Con()) {
1398 assert(has_node(n), "no dead nodes");
1399 split_if_with_blocks_post( n );
1400 }
1401 if (nstack.is_empty()) {
1402 // Finished all nodes on stack.
1403 break;
1404 }
1405 // Get saved parent node and next use's index. Visit the rest of uses.
1406 n = nstack.node();
1407 cnt = n->outcnt();
1408 i = nstack.index();
1409 nstack.pop();
1410 }
1411 }
1412 }
1413
1414
1415 //=============================================================================
1416 //
1417 // C L O N E A L O O P B O D Y
1418 //
1419
1420 //------------------------------clone_iff--------------------------------------
1421 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1422 // "Nearly" because all Nodes have been cloned from the original in the loop,
1423 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1424 // through the Phi recursively, and return a Bool.
1425 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1426
1427 // Convert this Phi into a Phi merging Bools
1428 uint i;
1429 for( i = 1; i < phi->req(); i++ ) {
1430 Node *b = phi->in(i);
1431 if( b->is_Phi() ) {
1432 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1433 } else {
1434 assert( b->is_Bool(), "" );
1435 }
1436 }
1437
1438 Node *sample_bool = phi->in(1);
1439 Node *sample_cmp = sample_bool->in(1);
1440
1441 // Make Phis to merge the Cmp's inputs.
1442 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1443 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1444 for( i = 1; i < phi->req(); i++ ) {
1445 Node *n1 = phi->in(i)->in(1)->in(1);
1446 Node *n2 = phi->in(i)->in(1)->in(2);
1447 phi1->set_req( i, n1 );
1448 phi2->set_req( i, n2 );
1449 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1450 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1451 }
1452 // See if these Phis have been made before.
1453 // Register with optimizer
1454 Node *hit1 = _igvn.hash_find_insert(phi1);
1455 if( hit1 ) { // Hit, toss just made Phi
1456 _igvn.remove_dead_node(phi1); // Remove new phi
1457 assert( hit1->is_Phi(), "" );
1458 phi1 = (PhiNode*)hit1; // Use existing phi
1459 } else { // Miss
1460 _igvn.register_new_node_with_optimizer(phi1);
1461 }
1462 Node *hit2 = _igvn.hash_find_insert(phi2);
1463 if( hit2 ) { // Hit, toss just made Phi
1464 _igvn.remove_dead_node(phi2); // Remove new phi
1465 assert( hit2->is_Phi(), "" );
1466 phi2 = (PhiNode*)hit2; // Use existing phi
1467 } else { // Miss
1468 _igvn.register_new_node_with_optimizer(phi2);
1469 }
1470 // Register Phis with loop/block info
1471 set_ctrl(phi1, phi->in(0));
1472 set_ctrl(phi2, phi->in(0));
1473 // Make a new Cmp
1474 Node *cmp = sample_cmp->clone();
1475 cmp->set_req( 1, phi1 );
1476 cmp->set_req( 2, phi2 );
1477 _igvn.register_new_node_with_optimizer(cmp);
1478 set_ctrl(cmp, phi->in(0));
1479
1480 // Make a new Bool
1481 Node *b = sample_bool->clone();
1482 b->set_req(1,cmp);
1483 _igvn.register_new_node_with_optimizer(b);
1484 set_ctrl(b, phi->in(0));
1485
1486 assert( b->is_Bool(), "" );
1487 return (BoolNode*)b;
1488 }
1489
1490 //------------------------------clone_bool-------------------------------------
1491 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1492 // "Nearly" because all Nodes have been cloned from the original in the loop,
1493 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1494 // through the Phi recursively, and return a Bool.
1495 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1496 uint i;
1497 // Convert this Phi into a Phi merging Bools
1498 for( i = 1; i < phi->req(); i++ ) {
1499 Node *b = phi->in(i);
1500 if( b->is_Phi() ) {
1501 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1502 } else {
1503 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1504 }
1505 }
1506
1507 Node *sample_cmp = phi->in(1);
1508
1509 // Make Phis to merge the Cmp's inputs.
1510 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1511 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1512 for( uint j = 1; j < phi->req(); j++ ) {
1513 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1514 Node *n1, *n2;
1515 if( cmp_top->is_Cmp() ) {
1516 n1 = cmp_top->in(1);
1517 n2 = cmp_top->in(2);
1518 } else {
1519 n1 = n2 = cmp_top;
1520 }
1521 phi1->set_req( j, n1 );
1522 phi2->set_req( j, n2 );
1523 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1524 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1525 }
1526
1527 // See if these Phis have been made before.
1528 // Register with optimizer
1529 Node *hit1 = _igvn.hash_find_insert(phi1);
1530 if( hit1 ) { // Hit, toss just made Phi
1531 _igvn.remove_dead_node(phi1); // Remove new phi
1532 assert( hit1->is_Phi(), "" );
1533 phi1 = (PhiNode*)hit1; // Use existing phi
1534 } else { // Miss
1535 _igvn.register_new_node_with_optimizer(phi1);
1536 }
1537 Node *hit2 = _igvn.hash_find_insert(phi2);
1538 if( hit2 ) { // Hit, toss just made Phi
1539 _igvn.remove_dead_node(phi2); // Remove new phi
1540 assert( hit2->is_Phi(), "" );
1541 phi2 = (PhiNode*)hit2; // Use existing phi
1542 } else { // Miss
1543 _igvn.register_new_node_with_optimizer(phi2);
1544 }
1545 // Register Phis with loop/block info
1546 set_ctrl(phi1, phi->in(0));
1547 set_ctrl(phi2, phi->in(0));
1548 // Make a new Cmp
1549 Node *cmp = sample_cmp->clone();
1550 cmp->set_req( 1, phi1 );
1551 cmp->set_req( 2, phi2 );
1552 _igvn.register_new_node_with_optimizer(cmp);
1553 set_ctrl(cmp, phi->in(0));
1554
1555 assert( cmp->is_Cmp(), "" );
1556 return (CmpNode*)cmp;
1557 }
1558
1559 //------------------------------sink_use---------------------------------------
1560 // If 'use' was in the loop-exit block, it now needs to be sunk
1561 // below the post-loop merge point.
1562 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1563 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1564 set_ctrl(use, post_loop);
1565 for (DUIterator j = use->outs(); use->has_out(j); j++)
1566 sink_use(use->out(j), post_loop);
1567 }
1568 }
1569
1570 //------------------------------clone_loop-------------------------------------
1571 //
1572 // C L O N E A L O O P B O D Y
1573 //
1574 // This is the basic building block of the loop optimizations. It clones an
1575 // entire loop body. It makes an old_new loop body mapping; with this mapping
1576 // you can find the new-loop equivalent to an old-loop node. All new-loop
1577 // nodes are exactly equal to their old-loop counterparts, all edges are the
1578 // same. All exits from the old-loop now have a RegionNode that merges the
1579 // equivalent new-loop path. This is true even for the normal "loop-exit"
1580 // condition. All uses of loop-invariant old-loop values now come from (one
1581 // or more) Phis that merge their new-loop equivalents.
1582 //
1583 // This operation leaves the graph in an illegal state: there are two valid
1584 // control edges coming from the loop pre-header to both loop bodies. I'll
1585 // definitely have to hack the graph after running this transform.
1586 //
1587 // From this building block I will further edit edges to perform loop peeling
1588 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1589 //
1590 // Parameter side_by_size_idom:
1591 // When side_by_size_idom is NULL, the dominator tree is constructed for
1592 // the clone loop to dominate the original. Used in construction of
1593 // pre-main-post loop sequence.
1594 // When nonnull, the clone and original are side-by-side, both are
1595 // dominated by the side_by_side_idom node. Used in construction of
1596 // unswitched loops.
1597 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1598 Node* side_by_side_idom) {
1599
1600 if (C->do_vector_loop() && PrintOpto) {
1601 const char* mname = C->method()->name()->as_quoted_ascii();
1602 if (mname != NULL) {
1603 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1604 }
1605 }
1606
1607 CloneMap& cm = C->clone_map();
1608 Dict* dict = cm.dict();
1609 if (C->do_vector_loop()) {
1610 cm.set_clone_idx(cm.max_gen()+1);
1611 #ifndef PRODUCT
1612 if (PrintOpto) {
1613 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1614 loop->dump_head();
1615 }
1616 #endif
1617 }
1618
1619 // Step 1: Clone the loop body. Make the old->new mapping.
1620 uint i;
1621 for( i = 0; i < loop->_body.size(); i++ ) {
1622 Node *old = loop->_body.at(i);
1623 Node *nnn = old->clone();
1624 old_new.map( old->_idx, nnn );
1625 if (C->do_vector_loop()) {
1626 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1627 }
1628 _igvn.register_new_node_with_optimizer(nnn);
1629 }
1630
1631
1632 // Step 2: Fix the edges in the new body. If the old input is outside the
1633 // loop use it. If the old input is INside the loop, use the corresponding
1634 // new node instead.
1635 for( i = 0; i < loop->_body.size(); i++ ) {
1636 Node *old = loop->_body.at(i);
1637 Node *nnn = old_new[old->_idx];
1638 // Fix CFG/Loop controlling the new node
1639 if (has_ctrl(old)) {
1640 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1641 } else {
1642 set_loop(nnn, loop->_parent);
1643 if (old->outcnt() > 0) {
1644 set_idom( nnn, old_new[idom(old)->_idx], dd );
1645 }
1646 }
1647 // Correct edges to the new node
1648 for( uint j = 0; j < nnn->req(); j++ ) {
1649 Node *n = nnn->in(j);
1650 if( n ) {
1651 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1652 if( loop->is_member( old_in_loop ) )
1653 nnn->set_req(j, old_new[n->_idx]);
1654 }
1655 }
1656 _igvn.hash_find_insert(nnn);
1657 }
1658 Node *newhead = old_new[loop->_head->_idx];
1659 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1660
1661
1662 // Step 3: Now fix control uses. Loop varying control uses have already
1663 // been fixed up (as part of all input edges in Step 2). Loop invariant
1664 // control uses must be either an IfFalse or an IfTrue. Make a merge
1665 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1666 // refer to this.
1667 ResourceArea *area = Thread::current()->resource_area();
1668 Node_List worklist(area);
1669 uint new_counter = C->unique();
1670 for( i = 0; i < loop->_body.size(); i++ ) {
1671 Node* old = loop->_body.at(i);
1672 if( !old->is_CFG() ) continue;
1673 Node* nnn = old_new[old->_idx];
1674
1675 // Copy uses to a worklist, so I can munge the def-use info
1676 // with impunity.
1677 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1678 worklist.push(old->fast_out(j));
1679
1680 while( worklist.size() ) { // Visit all uses
1681 Node *use = worklist.pop();
1682 if (!has_node(use)) continue; // Ignore dead nodes
1683 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1684 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1685 // Both OLD and USE are CFG nodes here.
1686 assert( use->is_Proj(), "" );
1687
1688 // Clone the loop exit control projection
1689 Node *newuse = use->clone();
1690 if (C->do_vector_loop()) {
1691 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1692 }
1693 newuse->set_req(0,nnn);
1694 _igvn.register_new_node_with_optimizer(newuse);
1695 set_loop(newuse, use_loop);
1696 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1697
1698 // We need a Region to merge the exit from the peeled body and the
1699 // exit from the old loop body.
1700 RegionNode *r = new RegionNode(3);
1701 // Map the old use to the new merge point
1702 old_new.map( use->_idx, r );
1703 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1704 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1705
1706 // The original user of 'use' uses 'r' instead.
1707 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1708 Node* useuse = use->last_out(l);
1709 _igvn.rehash_node_delayed(useuse);
1710 uint uses_found = 0;
1711 if( useuse->in(0) == use ) {
1712 useuse->set_req(0, r);
1713 uses_found++;
1714 if( useuse->is_CFG() ) {
1715 assert( dom_depth(useuse) > dd_r, "" );
1716 set_idom(useuse, r, dom_depth(useuse));
1717 }
1718 }
1719 for( uint k = 1; k < useuse->req(); k++ ) {
1720 if( useuse->in(k) == use ) {
1721 useuse->set_req(k, r);
1722 uses_found++;
1723 }
1724 }
1725 l -= uses_found; // we deleted 1 or more copies of this edge
1726 }
1727
1728 // Now finish up 'r'
1729 r->set_req( 1, newuse );
1730 r->set_req( 2, use );
1731 _igvn.register_new_node_with_optimizer(r);
1732 set_loop(r, use_loop);
1733 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1734 } // End of if a loop-exit test
1735 }
1736 }
1737
1738 // Step 4: If loop-invariant use is not control, it must be dominated by a
1739 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1740 // there if needed. Make a Phi there merging old and new used values.
1741 Node_List *split_if_set = NULL;
1742 Node_List *split_bool_set = NULL;
1743 Node_List *split_cex_set = NULL;
1744 for( i = 0; i < loop->_body.size(); i++ ) {
1745 Node* old = loop->_body.at(i);
1746 Node* nnn = old_new[old->_idx];
1747 // Copy uses to a worklist, so I can munge the def-use info
1748 // with impunity.
1749 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1750 worklist.push(old->fast_out(j));
1751
1752 while( worklist.size() ) {
1753 Node *use = worklist.pop();
1754 if (!has_node(use)) continue; // Ignore dead nodes
1755 if (use->in(0) == C->top()) continue;
1756 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1757 // Check for data-use outside of loop - at least one of OLD or USE
1758 // must not be a CFG node.
1759 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1760
1761 // If the Data use is an IF, that means we have an IF outside of the
1762 // loop that is switching on a condition that is set inside of the
1763 // loop. Happens if people set a loop-exit flag; then test the flag
1764 // in the loop to break the loop, then test is again outside of the
1765 // loop to determine which way the loop exited.
1766 // Loop predicate If node connects to Bool node through Opaque1 node.
1767 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1768 // Since this code is highly unlikely, we lazily build the worklist
1769 // of such Nodes to go split.
1770 if( !split_if_set )
1771 split_if_set = new Node_List(area);
1772 split_if_set->push(use);
1773 }
1774 if( use->is_Bool() ) {
1775 if( !split_bool_set )
1776 split_bool_set = new Node_List(area);
1777 split_bool_set->push(use);
1778 }
1779 if( use->Opcode() == Op_CreateEx ) {
1780 if( !split_cex_set )
1781 split_cex_set = new Node_List(area);
1782 split_cex_set->push(use);
1783 }
1784
1785
1786 // Get "block" use is in
1787 uint idx = 0;
1788 while( use->in(idx) != old ) idx++;
1789 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1790 assert( !loop->is_member( get_loop( prev ) ), "" );
1791 Node *cfg = prev->_idx >= new_counter
1792 ? prev->in(2)
1793 : idom(prev);
1794 if( use->is_Phi() ) // Phi use is in prior block
1795 cfg = prev->in(idx); // NOT in block of Phi itself
1796 if (cfg->is_top()) { // Use is dead?
1797 _igvn.replace_input_of(use, idx, C->top());
1798 continue;
1799 }
1800
1801 while( !loop->is_member( get_loop( cfg ) ) ) {
1802 prev = cfg;
1803 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1804 }
1805 // If the use occurs after merging several exits from the loop, then
1806 // old value must have dominated all those exits. Since the same old
1807 // value was used on all those exits we did not need a Phi at this
1808 // merge point. NOW we do need a Phi here. Each loop exit value
1809 // is now merged with the peeled body exit; each exit gets its own
1810 // private Phi and those Phis need to be merged here.
1811 Node *phi;
1812 if( prev->is_Region() ) {
1813 if( idx == 0 ) { // Updating control edge?
1814 phi = prev; // Just use existing control
1815 } else { // Else need a new Phi
1816 phi = PhiNode::make( prev, old );
1817 // Now recursively fix up the new uses of old!
1818 for( uint i = 1; i < prev->req(); i++ ) {
1819 worklist.push(phi); // Onto worklist once for each 'old' input
1820 }
1821 }
1822 } else {
1823 // Get new RegionNode merging old and new loop exits
1824 prev = old_new[prev->_idx];
1825 assert( prev, "just made this in step 7" );
1826 if( idx == 0 ) { // Updating control edge?
1827 phi = prev; // Just use existing control
1828 } else { // Else need a new Phi
1829 // Make a new Phi merging data values properly
1830 phi = PhiNode::make( prev, old );
1831 phi->set_req( 1, nnn );
1832 }
1833 }
1834 // If inserting a new Phi, check for prior hits
1835 if( idx != 0 ) {
1836 Node *hit = _igvn.hash_find_insert(phi);
1837 if( hit == NULL ) {
1838 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1839 } else { // or
1840 // Remove the new phi from the graph and use the hit
1841 _igvn.remove_dead_node(phi);
1842 phi = hit; // Use existing phi
1843 }
1844 set_ctrl(phi, prev);
1845 }
1846 // Make 'use' use the Phi instead of the old loop body exit value
1847 _igvn.replace_input_of(use, idx, phi);
1848 if( use->_idx >= new_counter ) { // If updating new phis
1849 // Not needed for correctness, but prevents a weak assert
1850 // in AddPNode from tripping (when we end up with different
1851 // base & derived Phis that will become the same after
1852 // IGVN does CSE).
1853 Node *hit = _igvn.hash_find_insert(use);
1854 if( hit ) // Go ahead and re-hash for hits.
1855 _igvn.replace_node( use, hit );
1856 }
1857
1858 // If 'use' was in the loop-exit block, it now needs to be sunk
1859 // below the post-loop merge point.
1860 sink_use( use, prev );
1861 }
1862 }
1863 }
1864
1865 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1866 // the loop uses a condition set in the loop. The original IF probably
1867 // takes control from one or more OLD Regions (which in turn get from NEW
1868 // Regions). In any case, there will be a set of Phis for each merge point
1869 // from the IF up to where the original BOOL def exists the loop.
1870 if( split_if_set ) {
1871 while( split_if_set->size() ) {
1872 Node *iff = split_if_set->pop();
1873 if( iff->in(1)->is_Phi() ) {
1874 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1875 _igvn.replace_input_of(iff, 1, b);
1876 }
1877 }
1878 }
1879 if( split_bool_set ) {
1880 while( split_bool_set->size() ) {
1881 Node *b = split_bool_set->pop();
1882 Node *phi = b->in(1);
1883 assert( phi->is_Phi(), "" );
1884 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1885 _igvn.replace_input_of(b, 1, cmp);
1886 }
1887 }
1888 if( split_cex_set ) {
1889 while( split_cex_set->size() ) {
1890 Node *b = split_cex_set->pop();
1891 assert( b->in(0)->is_Region(), "" );
1892 assert( b->in(1)->is_Phi(), "" );
1893 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1894 split_up( b, b->in(0), NULL );
1895 }
1896 }
1897
1898 }
1899
1900
1901 //---------------------- stride_of_possible_iv -------------------------------------
1902 // Looks for an iff/bool/comp with one operand of the compare
1903 // being a cycle involving an add and a phi,
1904 // with an optional truncation (left-shift followed by a right-shift)
1905 // of the add. Returns zero if not an iv.
1906 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1907 Node* trunc1 = NULL;
1908 Node* trunc2 = NULL;
1909 const TypeInt* ttype = NULL;
1910 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1911 return 0;
1912 }
1913 BoolNode* bl = iff->in(1)->as_Bool();
1914 Node* cmp = bl->in(1);
1915 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1916 return 0;
1917 }
1918 // Must have an invariant operand
1919 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1920 return 0;
1921 }
1922 Node* add2 = NULL;
1923 Node* cmp1 = cmp->in(1);
1924 if (cmp1->is_Phi()) {
1925 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1926 Node* phi = cmp1;
1927 for (uint i = 1; i < phi->req(); i++) {
1928 Node* in = phi->in(i);
1929 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1930 &trunc1, &trunc2, &ttype);
1931 if (add && add->in(1) == phi) {
1932 add2 = add->in(2);
1933 break;
1934 }
1935 }
1936 } else {
1937 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1938 Node* addtrunc = cmp1;
1939 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1940 &trunc1, &trunc2, &ttype);
1941 if (add && add->in(1)->is_Phi()) {
1942 Node* phi = add->in(1);
1943 for (uint i = 1; i < phi->req(); i++) {
1944 if (phi->in(i) == addtrunc) {
1945 add2 = add->in(2);
1946 break;
1947 }
1948 }
1949 }
1950 }
1951 if (add2 != NULL) {
1952 const TypeInt* add2t = _igvn.type(add2)->is_int();
1953 if (add2t->is_con()) {
1954 return add2t->get_con();
1955 }
1956 }
1957 return 0;
1958 }
1959
1960
1961 //---------------------- stay_in_loop -------------------------------------
1962 // Return the (unique) control output node that's in the loop (if it exists.)
1963 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1964 Node* unique = NULL;
1965 if (!n) return NULL;
1966 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1967 Node* use = n->fast_out(i);
1968 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1969 if (unique != NULL) {
1970 return NULL;
1971 }
1972 unique = use;
1973 }
1974 }
1975 return unique;
1976 }
1977
1978 //------------------------------ register_node -------------------------------------
1979 // Utility to register node "n" with PhaseIdealLoop
1980 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1981 _igvn.register_new_node_with_optimizer(n);
1982 loop->_body.push(n);
1983 if (n->is_CFG()) {
1984 set_loop(n, loop);
1985 set_idom(n, pred, ddepth);
1986 } else {
1987 set_ctrl(n, pred);
1988 }
1989 }
1990
1991 //------------------------------ proj_clone -------------------------------------
1992 // Utility to create an if-projection
1993 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1994 ProjNode* c = p->clone()->as_Proj();
1995 c->set_req(0, iff);
1996 return c;
1997 }
1998
1999 //------------------------------ short_circuit_if -------------------------------------
2000 // Force the iff control output to be the live_proj
2001 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2002 guarantee(live_proj != NULL, "null projection");
2003 int proj_con = live_proj->_con;
2004 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2005 Node *con = _igvn.intcon(proj_con);
2006 set_ctrl(con, C->root());
2007 if (iff) {
2008 iff->set_req(1, con);
2009 }
2010 return con;
2011 }
2012
2013 //------------------------------ insert_if_before_proj -------------------------------------
2014 // Insert a new if before an if projection (* - new node)
2015 //
2016 // before
2017 // if(test)
2018 // / \
2019 // v v
2020 // other-proj proj (arg)
2021 //
2022 // after
2023 // if(test)
2024 // / \
2025 // / v
2026 // | * proj-clone
2027 // v |
2028 // other-proj v
2029 // * new_if(relop(cmp[IU](left,right)))
2030 // / \
2031 // v v
2032 // * new-proj proj
2033 // (returned)
2034 //
2035 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2036 IfNode* iff = proj->in(0)->as_If();
2037 IdealLoopTree *loop = get_loop(proj);
2038 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2039 int ddepth = dom_depth(proj);
2040
2041 _igvn.rehash_node_delayed(iff);
2042 _igvn.rehash_node_delayed(proj);
2043
2044 proj->set_req(0, NULL); // temporary disconnect
2045 ProjNode* proj2 = proj_clone(proj, iff);
2046 register_node(proj2, loop, iff, ddepth);
2047
2048 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2049 register_node(cmp, loop, proj2, ddepth);
2050
2051 BoolNode* bol = new BoolNode(cmp, relop);
2052 register_node(bol, loop, proj2, ddepth);
2053
2054 int opcode = iff->Opcode();
2055 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2056 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2057 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2058 register_node(new_if, loop, proj2, ddepth);
2059
2060 proj->set_req(0, new_if); // reattach
2061 set_idom(proj, new_if, ddepth);
2062
2063 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2064 guarantee(new_exit != NULL, "null exit node");
2065 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2066
2067 return new_exit;
2068 }
2069
2070 //------------------------------ insert_region_before_proj -------------------------------------
2071 // Insert a region before an if projection (* - new node)
2072 //
2073 // before
2074 // if(test)
2075 // / |
2076 // v |
2077 // proj v
2078 // other-proj
2079 //
2080 // after
2081 // if(test)
2082 // / |
2083 // v |
2084 // * proj-clone v
2085 // | other-proj
2086 // v
2087 // * new-region
2088 // |
2089 // v
2090 // * dum_if
2091 // / \
2092 // v \
2093 // * dum-proj v
2094 // proj
2095 //
2096 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2097 IfNode* iff = proj->in(0)->as_If();
2098 IdealLoopTree *loop = get_loop(proj);
2099 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2100 int ddepth = dom_depth(proj);
2101
2102 _igvn.rehash_node_delayed(iff);
2103 _igvn.rehash_node_delayed(proj);
2104
2105 proj->set_req(0, NULL); // temporary disconnect
2106 ProjNode* proj2 = proj_clone(proj, iff);
2107 register_node(proj2, loop, iff, ddepth);
2108
2109 RegionNode* reg = new RegionNode(2);
2110 reg->set_req(1, proj2);
2111 register_node(reg, loop, iff, ddepth);
2112
2113 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2114 register_node(dum_if, loop, reg, ddepth);
2115
2116 proj->set_req(0, dum_if); // reattach
2117 set_idom(proj, dum_if, ddepth);
2118
2119 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2120 register_node(dum_proj, loop, dum_if, ddepth);
2121
2122 return reg;
2123 }
2124
2125 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2126 // Clone a signed compare loop exit from an unsigned compare and
2127 // insert it before the unsigned cmp on the stay-in-loop path.
2128 // All new nodes inserted in the dominator tree between the original
2129 // if and it's projections. The original if test is replaced with
2130 // a constant to force the stay-in-loop path.
2131 //
2132 // This is done to make sure that the original if and it's projections
2133 // still dominate the same set of control nodes, that the ctrl() relation
2134 // from data nodes to them is preserved, and that their loop nesting is
2135 // preserved.
2136 //
2137 // before
2138 // if(i <u limit) unsigned compare loop exit
2139 // / |
2140 // v v
2141 // exit-proj stay-in-loop-proj
2142 //
2143 // after
2144 // if(stay-in-loop-const) original if
2145 // / |
2146 // / v
2147 // / if(i < limit) new signed test
2148 // / / |
2149 // / / v
2150 // / / if(i <u limit) new cloned unsigned test
2151 // / / / |
2152 // v v v |
2153 // region |
2154 // | |
2155 // dum-if |
2156 // / | |
2157 // ether | |
2158 // v v
2159 // exit-proj stay-in-loop-proj
2160 //
2161 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2162 const bool Signed = true;
2163 const bool Unsigned = false;
2164
2165 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2166 if (bol->_test._test != BoolTest::lt) return NULL;
2167 CmpNode* cmpu = bol->in(1)->as_Cmp();
2168 if (cmpu->Opcode() != Op_CmpU) return NULL;
2169 int stride = stride_of_possible_iv(if_cmpu);
2170 if (stride == 0) return NULL;
2171
2172 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2173 guarantee(lp_proj != NULL, "null loop node");
2174
2175 ProjNode* lp_continue = lp_proj->as_Proj();
2176 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2177
2178 Node* limit = NULL;
2179 if (stride > 0) {
2180 limit = cmpu->in(2);
2181 } else {
2182 limit = _igvn.makecon(TypeInt::ZERO);
2183 set_ctrl(limit, C->root());
2184 }
2185 // Create a new region on the exit path
2186 RegionNode* reg = insert_region_before_proj(lp_exit);
2187 guarantee(reg != NULL, "null region node");
2188
2189 // Clone the if-cmpu-true-false using a signed compare
2190 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2191 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2192 reg->add_req(cmpi_exit);
2193
2194 // Clone the if-cmpu-true-false
2195 BoolTest::mask rel_u = bol->_test._test;
2196 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2197 reg->add_req(cmpu_exit);
2198
2199 // Force original if to stay in loop.
2200 short_circuit_if(if_cmpu, lp_continue);
2201
2202 return cmpi_exit->in(0)->as_If();
2203 }
2204
2205 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2206 // Remove a previously inserted signed compare loop exit.
2207 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2208 Node* lp_proj = stay_in_loop(if_cmp, loop);
2209 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2210 stay_in_loop(lp_proj, loop)->is_If() &&
2211 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2212 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2213 set_ctrl(con, C->root());
2214 if_cmp->set_req(1, con);
2215 }
2216
2217 //------------------------------ scheduled_nodelist -------------------------------------
2218 // Create a post order schedule of nodes that are in the
2219 // "member" set. The list is returned in "sched".
2220 // The first node in "sched" is the loop head, followed by
2221 // nodes which have no inputs in the "member" set, and then
2222 // followed by the nodes that have an immediate input dependence
2223 // on a node in "sched".
2224 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2225
2226 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2227 Arena *a = Thread::current()->resource_area();
2228 VectorSet visited(a);
2229 Node_Stack nstack(a, loop->_body.size());
2230
2231 Node* n = loop->_head; // top of stack is cached in "n"
2232 uint idx = 0;
2233 visited.set(n->_idx);
2234
2235 // Initially push all with no inputs from within member set
2236 for(uint i = 0; i < loop->_body.size(); i++ ) {
2237 Node *elt = loop->_body.at(i);
2238 if (member.test(elt->_idx)) {
2239 bool found = false;
2240 for (uint j = 0; j < elt->req(); j++) {
2241 Node* def = elt->in(j);
2242 if (def && member.test(def->_idx) && def != elt) {
2243 found = true;
2244 break;
2245 }
2246 }
2247 if (!found && elt != loop->_head) {
2248 nstack.push(n, idx);
2249 n = elt;
2250 assert(!visited.test(n->_idx), "not seen yet");
2251 visited.set(n->_idx);
2252 }
2253 }
2254 }
2255
2256 // traverse out's that are in the member set
2257 while (true) {
2258 if (idx < n->outcnt()) {
2259 Node* use = n->raw_out(idx);
2260 idx++;
2261 if (!visited.test_set(use->_idx)) {
2262 if (member.test(use->_idx)) {
2263 nstack.push(n, idx);
2264 n = use;
2265 idx = 0;
2266 }
2267 }
2268 } else {
2269 // All outputs processed
2270 sched.push(n);
2271 if (nstack.is_empty()) break;
2272 n = nstack.node();
2273 idx = nstack.index();
2274 nstack.pop();
2275 }
2276 }
2277 }
2278
2279
2280 //------------------------------ has_use_in_set -------------------------------------
2281 // Has a use in the vector set
2282 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2283 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2284 Node* use = n->fast_out(j);
2285 if (vset.test(use->_idx)) {
2286 return true;
2287 }
2288 }
2289 return false;
2290 }
2291
2292
2293 //------------------------------ has_use_internal_to_set -------------------------------------
2294 // Has use internal to the vector set (ie. not in a phi at the loop head)
2295 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2296 Node* head = loop->_head;
2297 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2298 Node* use = n->fast_out(j);
2299 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2300 return true;
2301 }
2302 }
2303 return false;
2304 }
2305
2306
2307 //------------------------------ clone_for_use_outside_loop -------------------------------------
2308 // clone "n" for uses that are outside of loop
2309 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2310 int cloned = 0;
2311 assert(worklist.size() == 0, "should be empty");
2312 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2313 Node* use = n->fast_out(j);
2314 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2315 worklist.push(use);
2316 }
2317 }
2318 while( worklist.size() ) {
2319 Node *use = worklist.pop();
2320 if (!has_node(use) || use->in(0) == C->top()) continue;
2321 uint j;
2322 for (j = 0; j < use->req(); j++) {
2323 if (use->in(j) == n) break;
2324 }
2325 assert(j < use->req(), "must be there");
2326
2327 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2328 Node* n_clone = n->clone();
2329 _igvn.replace_input_of(use, j, n_clone);
2330 cloned++;
2331 Node* use_c;
2332 if (!use->is_Phi()) {
2333 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2334 } else {
2335 // Use in a phi is considered a use in the associated predecessor block
2336 use_c = use->in(0)->in(j);
2337 }
2338 set_ctrl(n_clone, use_c);
2339 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2340 get_loop(use_c)->_body.push(n_clone);
2341 _igvn.register_new_node_with_optimizer(n_clone);
2342 #if !defined(PRODUCT)
2343 if (TracePartialPeeling) {
2344 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2345 }
2346 #endif
2347 }
2348 return cloned;
2349 }
2350
2351
2352 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2353 // clone "n" for special uses that are in the not_peeled region.
2354 // If these def-uses occur in separate blocks, the code generator
2355 // marks the method as not compilable. For example, if a "BoolNode"
2356 // is in a different basic block than the "IfNode" that uses it, then
2357 // the compilation is aborted in the code generator.
2358 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2359 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2360 if (n->is_Phi() || n->is_Load()) {
2361 return;
2362 }
2363 assert(worklist.size() == 0, "should be empty");
2364 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2365 Node* use = n->fast_out(j);
2366 if ( not_peel.test(use->_idx) &&
2367 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2368 use->in(1) == n) {
2369 worklist.push(use);
2370 }
2371 }
2372 if (worklist.size() > 0) {
2373 // clone "n" and insert it between inputs of "n" and the use
2374 Node* n_clone = n->clone();
2375 loop->_body.push(n_clone);
2376 _igvn.register_new_node_with_optimizer(n_clone);
2377 set_ctrl(n_clone, get_ctrl(n));
2378 sink_list.push(n_clone);
2379 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2380 #if !defined(PRODUCT)
2381 if (TracePartialPeeling) {
2382 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2383 }
2384 #endif
2385 while( worklist.size() ) {
2386 Node *use = worklist.pop();
2387 _igvn.rehash_node_delayed(use);
2388 for (uint j = 1; j < use->req(); j++) {
2389 if (use->in(j) == n) {
2390 use->set_req(j, n_clone);
2391 }
2392 }
2393 }
2394 }
2395 }
2396
2397
2398 //------------------------------ insert_phi_for_loop -------------------------------------
2399 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2400 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2401 Node *phi = PhiNode::make(lp, back_edge_val);
2402 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2403 // Use existing phi if it already exists
2404 Node *hit = _igvn.hash_find_insert(phi);
2405 if( hit == NULL ) {
2406 _igvn.register_new_node_with_optimizer(phi);
2407 set_ctrl(phi, lp);
2408 } else {
2409 // Remove the new phi from the graph and use the hit
2410 _igvn.remove_dead_node(phi);
2411 phi = hit;
2412 }
2413 _igvn.replace_input_of(use, idx, phi);
2414 }
2415
2416 #ifdef ASSERT
2417 //------------------------------ is_valid_loop_partition -------------------------------------
2418 // Validate the loop partition sets: peel and not_peel
2419 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2420 VectorSet& not_peel ) {
2421 uint i;
2422 // Check that peel_list entries are in the peel set
2423 for (i = 0; i < peel_list.size(); i++) {
2424 if (!peel.test(peel_list.at(i)->_idx)) {
2425 return false;
2426 }
2427 }
2428 // Check at loop members are in one of peel set or not_peel set
2429 for (i = 0; i < loop->_body.size(); i++ ) {
2430 Node *def = loop->_body.at(i);
2431 uint di = def->_idx;
2432 // Check that peel set elements are in peel_list
2433 if (peel.test(di)) {
2434 if (not_peel.test(di)) {
2435 return false;
2436 }
2437 // Must be in peel_list also
2438 bool found = false;
2439 for (uint j = 0; j < peel_list.size(); j++) {
2440 if (peel_list.at(j)->_idx == di) {
2441 found = true;
2442 break;
2443 }
2444 }
2445 if (!found) {
2446 return false;
2447 }
2448 } else if (not_peel.test(di)) {
2449 if (peel.test(di)) {
2450 return false;
2451 }
2452 } else {
2453 return false;
2454 }
2455 }
2456 return true;
2457 }
2458
2459 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2460 // Ensure a use outside of loop is of the right form
2461 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2462 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2463 return (use->is_Phi() &&
2464 use_c->is_Region() && use_c->req() == 3 &&
2465 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2466 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2467 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2468 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2469 }
2470
2471 //------------------------------ is_valid_clone_loop_form -------------------------------------
2472 // Ensure that all uses outside of loop are of the right form
2473 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2474 uint orig_exit_idx, uint clone_exit_idx) {
2475 uint len = peel_list.size();
2476 for (uint i = 0; i < len; i++) {
2477 Node *def = peel_list.at(i);
2478
2479 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2480 Node *use = def->fast_out(j);
2481 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2482 if (!loop->is_member(get_loop(use_c))) {
2483 // use is not in the loop, check for correct structure
2484 if (use->in(0) == def) {
2485 // Okay
2486 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2487 return false;
2488 }
2489 }
2490 }
2491 }
2492 return true;
2493 }
2494 #endif
2495
2496 //------------------------------ partial_peel -------------------------------------
2497 // Partially peel (aka loop rotation) the top portion of a loop (called
2498 // the peel section below) by cloning it and placing one copy just before
2499 // the new loop head and the other copy at the bottom of the new loop.
2500 //
2501 // before after where it came from
2502 //
2503 // stmt1 stmt1
2504 // loop: stmt2 clone
2505 // stmt2 if condA goto exitA clone
2506 // if condA goto exitA new_loop: new
2507 // stmt3 stmt3 clone
2508 // if !condB goto loop if condB goto exitB clone
2509 // exitB: stmt2 orig
2510 // stmt4 if !condA goto new_loop orig
2511 // exitA: goto exitA
2512 // exitB:
2513 // stmt4
2514 // exitA:
2515 //
2516 // Step 1: find the cut point: an exit test on probable
2517 // induction variable.
2518 // Step 2: schedule (with cloning) operations in the peel
2519 // section that can be executed after the cut into
2520 // the section that is not peeled. This may need
2521 // to clone operations into exit blocks. For
2522 // instance, a reference to A[i] in the not-peel
2523 // section and a reference to B[i] in an exit block
2524 // may cause a left-shift of i by 2 to be placed
2525 // in the peel block. This step will clone the left
2526 // shift into the exit block and sink the left shift
2527 // from the peel to the not-peel section.
2528 // Step 3: clone the loop, retarget the control, and insert
2529 // phis for values that are live across the new loop
2530 // head. This is very dependent on the graph structure
2531 // from clone_loop. It creates region nodes for
2532 // exit control and associated phi nodes for values
2533 // flow out of the loop through that exit. The region
2534 // node is dominated by the clone's control projection.
2535 // So the clone's peel section is placed before the
2536 // new loop head, and the clone's not-peel section is
2537 // forms the top part of the new loop. The original
2538 // peel section forms the tail of the new loop.
2539 // Step 4: update the dominator tree and recompute the
2540 // dominator depth.
2541 //
2542 // orig
2543 //
2544 // stmt1
2545 // |
2546 // v
2547 // loop predicate
2548 // |
2549 // v
2550 // loop<----+
2551 // | |
2552 // stmt2 |
2553 // | |
2554 // v |
2555 // ifA |
2556 // / | |
2557 // v v |
2558 // false true ^ <-- last_peel
2559 // / | |
2560 // / ===|==cut |
2561 // / stmt3 | <-- first_not_peel
2562 // / | |
2563 // | v |
2564 // v ifB |
2565 // exitA: / \ |
2566 // / \ |
2567 // v v |
2568 // false true |
2569 // / \ |
2570 // / ----+
2571 // |
2572 // v
2573 // exitB:
2574 // stmt4
2575 //
2576 //
2577 // after clone loop
2578 //
2579 // stmt1
2580 // |
2581 // v
2582 // loop predicate
2583 // / \
2584 // clone / \ orig
2585 // / \
2586 // / \
2587 // v v
2588 // +---->loop loop<----+
2589 // | | | |
2590 // | stmt2 stmt2 |
2591 // | | | |
2592 // | v v |
2593 // | ifA ifA |
2594 // | | \ / | |
2595 // | v v v v |
2596 // ^ true false false true ^ <-- last_peel
2597 // | | ^ \ / | |
2598 // | cut==|== \ \ / ===|==cut |
2599 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2600 // | | dom | | | |
2601 // | v \ 1v v2 v |
2602 // | ifB regionA ifB |
2603 // | / \ | / \ |
2604 // | / \ v / \ |
2605 // | v v exitA: v v |
2606 // | true false false true |
2607 // | / ^ \ / \ |
2608 // +---- \ \ / ----+
2609 // dom \ /
2610 // \ 1v v2
2611 // regionB
2612 // |
2613 // v
2614 // exitB:
2615 // stmt4
2616 //
2617 //
2618 // after partial peel
2619 //
2620 // stmt1
2621 // |
2622 // v
2623 // loop predicate
2624 // /
2625 // clone / orig
2626 // / TOP
2627 // / \
2628 // v v
2629 // TOP->loop loop----+
2630 // | | |
2631 // stmt2 stmt2 |
2632 // | | |
2633 // v v |
2634 // ifA ifA |
2635 // | \ / | |
2636 // v v v v |
2637 // true false false true | <-- last_peel
2638 // | ^ \ / +------|---+
2639 // +->newloop \ \ / === ==cut | |
2640 // | stmt3 \ \ / TOP | |
2641 // | | dom | | stmt3 | | <-- first_not_peel
2642 // | v \ 1v v2 v | |
2643 // | ifB regionA ifB ^ v
2644 // | / \ | / \ | |
2645 // | / \ v / \ | |
2646 // | v v exitA: v v | |
2647 // | true false false true | |
2648 // | / ^ \ / \ | |
2649 // | | \ \ / v | |
2650 // | | dom \ / TOP | |
2651 // | | \ 1v v2 | |
2652 // ^ v regionB | |
2653 // | | | | |
2654 // | | v ^ v
2655 // | | exitB: | |
2656 // | | stmt4 | |
2657 // | +------------>-----------------+ |
2658 // | |
2659 // +-----------------<---------------------+
2660 //
2661 //
2662 // final graph
2663 //
2664 // stmt1
2665 // |
2666 // v
2667 // loop predicate
2668 // |
2669 // v
2670 // stmt2 clone
2671 // |
2672 // v
2673 // ........> ifA clone
2674 // : / |
2675 // dom / |
2676 // : v v
2677 // : false true
2678 // : | |
2679 // : | v
2680 // : | newloop<-----+
2681 // : | | |
2682 // : | stmt3 clone |
2683 // : | | |
2684 // : | v |
2685 // : | ifB |
2686 // : | / \ |
2687 // : | v v |
2688 // : | false true |
2689 // : | | | |
2690 // : | v stmt2 |
2691 // : | exitB: | |
2692 // : | stmt4 v |
2693 // : | ifA orig |
2694 // : | / \ |
2695 // : | / \ |
2696 // : | v v |
2697 // : | false true |
2698 // : | / \ |
2699 // : v v -----+
2700 // RegionA
2701 // |
2702 // v
2703 // exitA
2704 //
2705 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2706
2707 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2708 if (!loop->_head->is_Loop()) {
2709 return false; }
2710
2711 LoopNode *head = loop->_head->as_Loop();
2712
2713 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2714 return false;
2715 }
2716
2717 // Check for complex exit control
2718 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2719 Node *n = loop->_body.at(ii);
2720 int opc = n->Opcode();
2721 if (n->is_Call() ||
2722 opc == Op_Catch ||
2723 opc == Op_CatchProj ||
2724 opc == Op_Jump ||
2725 opc == Op_JumpProj) {
2726 #if !defined(PRODUCT)
2727 if (TracePartialPeeling) {
2728 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2729 }
2730 #endif
2731 return false;
2732 }
2733 }
2734
2735 int dd = dom_depth(head);
2736
2737 // Step 1: find cut point
2738
2739 // Walk up dominators to loop head looking for first loop exit
2740 // which is executed on every path thru loop.
2741 IfNode *peel_if = NULL;
2742 IfNode *peel_if_cmpu = NULL;
2743
2744 Node *iff = loop->tail();
2745 while( iff != head ) {
2746 if( iff->is_If() ) {
2747 Node *ctrl = get_ctrl(iff->in(1));
2748 if (ctrl->is_top()) return false; // Dead test on live IF.
2749 // If loop-varying exit-test, check for induction variable
2750 if( loop->is_member(get_loop(ctrl)) &&
2751 loop->is_loop_exit(iff) &&
2752 is_possible_iv_test(iff)) {
2753 Node* cmp = iff->in(1)->in(1);
2754 if (cmp->Opcode() == Op_CmpI) {
2755 peel_if = iff->as_If();
2756 } else {
2757 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2758 peel_if_cmpu = iff->as_If();
2759 }
2760 }
2761 }
2762 iff = idom(iff);
2763 }
2764 // Prefer signed compare over unsigned compare.
2765 IfNode* new_peel_if = NULL;
2766 if (peel_if == NULL) {
2767 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2768 return false; // No peel point found
2769 }
2770 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2771 if (new_peel_if == NULL) {
2772 return false; // No peel point found
2773 }
2774 peel_if = new_peel_if;
2775 }
2776 Node* last_peel = stay_in_loop(peel_if, loop);
2777 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2778 if (first_not_peeled == NULL || first_not_peeled == head) {
2779 return false;
2780 }
2781
2782 #if !defined(PRODUCT)
2783 if (TraceLoopOpts) {
2784 tty->print("PartialPeel ");
2785 loop->dump_head();
2786 }
2787
2788 if (TracePartialPeeling) {
2789 tty->print_cr("before partial peel one iteration");
2790 Node_List wl;
2791 Node* t = head->in(2);
2792 while (true) {
2793 wl.push(t);
2794 if (t == head) break;
2795 t = idom(t);
2796 }
2797 while (wl.size() > 0) {
2798 Node* tt = wl.pop();
2799 tt->dump();
2800 if (tt == last_peel) tty->print_cr("-- cut --");
2801 }
2802 }
2803 #endif
2804 ResourceArea *area = Thread::current()->resource_area();
2805 VectorSet peel(area);
2806 VectorSet not_peel(area);
2807 Node_List peel_list(area);
2808 Node_List worklist(area);
2809 Node_List sink_list(area);
2810
2811 // Set of cfg nodes to peel are those that are executable from
2812 // the head through last_peel.
2813 assert(worklist.size() == 0, "should be empty");
2814 worklist.push(head);
2815 peel.set(head->_idx);
2816 while (worklist.size() > 0) {
2817 Node *n = worklist.pop();
2818 if (n != last_peel) {
2819 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2820 Node* use = n->fast_out(j);
2821 if (use->is_CFG() &&
2822 loop->is_member(get_loop(use)) &&
2823 !peel.test_set(use->_idx)) {
2824 worklist.push(use);
2825 }
2826 }
2827 }
2828 }
2829
2830 // Set of non-cfg nodes to peel are those that are control
2831 // dependent on the cfg nodes.
2832 uint i;
2833 for(i = 0; i < loop->_body.size(); i++ ) {
2834 Node *n = loop->_body.at(i);
2835 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2836 if (peel.test(n_c->_idx)) {
2837 peel.set(n->_idx);
2838 } else {
2839 not_peel.set(n->_idx);
2840 }
2841 }
2842
2843 // Step 2: move operations from the peeled section down into the
2844 // not-peeled section
2845
2846 // Get a post order schedule of nodes in the peel region
2847 // Result in right-most operand.
2848 scheduled_nodelist(loop, peel, peel_list );
2849
2850 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2851
2852 // For future check for too many new phis
2853 uint old_phi_cnt = 0;
2854 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2855 Node* use = head->fast_out(j);
2856 if (use->is_Phi()) old_phi_cnt++;
2857 }
2858
2859 #if !defined(PRODUCT)
2860 if (TracePartialPeeling) {
2861 tty->print_cr("\npeeled list");
2862 }
2863 #endif
2864
2865 // Evacuate nodes in peel region into the not_peeled region if possible
2866 uint new_phi_cnt = 0;
2867 uint cloned_for_outside_use = 0;
2868 for (i = 0; i < peel_list.size();) {
2869 Node* n = peel_list.at(i);
2870 #if !defined(PRODUCT)
2871 if (TracePartialPeeling) n->dump();
2872 #endif
2873 bool incr = true;
2874 if ( !n->is_CFG() ) {
2875
2876 if ( has_use_in_set(n, not_peel) ) {
2877
2878 // If not used internal to the peeled region,
2879 // move "n" from peeled to not_peeled region.
2880
2881 if ( !has_use_internal_to_set(n, peel, loop) ) {
2882
2883 // if not pinned and not a load (which maybe anti-dependent on a store)
2884 // and not a CMove (Matcher expects only bool->cmove).
2885 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2886 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2887 sink_list.push(n);
2888 peel >>= n->_idx; // delete n from peel set.
2889 not_peel <<= n->_idx; // add n to not_peel set.
2890 peel_list.remove(i);
2891 incr = false;
2892 #if !defined(PRODUCT)
2893 if (TracePartialPeeling) {
2894 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2895 n->_idx, get_ctrl(n)->_idx);
2896 }
2897 #endif
2898 }
2899 } else {
2900 // Otherwise check for special def-use cases that span
2901 // the peel/not_peel boundary such as bool->if
2902 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2903 new_phi_cnt++;
2904 }
2905 }
2906 }
2907 if (incr) i++;
2908 }
2909
2910 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2911 #if !defined(PRODUCT)
2912 if (TracePartialPeeling) {
2913 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2914 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2915 }
2916 #endif
2917 if (new_peel_if != NULL) {
2918 remove_cmpi_loop_exit(new_peel_if, loop);
2919 }
2920 // Inhibit more partial peeling on this loop
2921 assert(!head->is_partial_peel_loop(), "not partial peeled");
2922 head->mark_partial_peel_failed();
2923 if (cloned_for_outside_use > 0) {
2924 // Terminate this round of loop opts because
2925 // the graph outside this loop was changed.
2926 C->set_major_progress();
2927 return true;
2928 }
2929 return false;
2930 }
2931
2932 // Step 3: clone loop, retarget control, and insert new phis
2933
2934 // Create new loop head for new phis and to hang
2935 // the nodes being moved (sinked) from the peel region.
2936 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2937 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2938 _igvn.register_new_node_with_optimizer(new_head);
2939 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2940 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2941 set_loop(new_head, loop);
2942 loop->_body.push(new_head);
2943 not_peel.set(new_head->_idx);
2944 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2945 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2946
2947 while (sink_list.size() > 0) {
2948 Node* n = sink_list.pop();
2949 set_ctrl(n, new_head);
2950 }
2951
2952 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2953
2954 clone_loop( loop, old_new, dd );
2955
2956 const uint clone_exit_idx = 1;
2957 const uint orig_exit_idx = 2;
2958 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2959
2960 Node* head_clone = old_new[head->_idx];
2961 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2962 Node* orig_tail_clone = head_clone->in(2);
2963
2964 // Add phi if "def" node is in peel set and "use" is not
2965
2966 for(i = 0; i < peel_list.size(); i++ ) {
2967 Node *def = peel_list.at(i);
2968 if (!def->is_CFG()) {
2969 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2970 Node *use = def->fast_out(j);
2971 if (has_node(use) && use->in(0) != C->top() &&
2972 (!peel.test(use->_idx) ||
2973 (use->is_Phi() && use->in(0) == head)) ) {
2974 worklist.push(use);
2975 }
2976 }
2977 while( worklist.size() ) {
2978 Node *use = worklist.pop();
2979 for (uint j = 1; j < use->req(); j++) {
2980 Node* n = use->in(j);
2981 if (n == def) {
2982
2983 // "def" is in peel set, "use" is not in peel set
2984 // or "use" is in the entry boundary (a phi) of the peel set
2985
2986 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2987
2988 if ( loop->is_member(get_loop( use_c )) ) {
2989 // use is in loop
2990 if (old_new[use->_idx] != NULL) { // null for dead code
2991 Node* use_clone = old_new[use->_idx];
2992 _igvn.replace_input_of(use, j, C->top());
2993 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2994 }
2995 } else {
2996 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2997 // use is not in the loop, check if the live range includes the cut
2998 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2999 if (not_peel.test(lp_if->_idx)) {
3000 assert(j == orig_exit_idx, "use from original loop");
3001 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3002 }
3003 }
3004 }
3005 }
3006 }
3007 }
3008 }
3009
3010 // Step 3b: retarget control
3011
3012 // Redirect control to the new loop head if a cloned node in
3013 // the not_peeled region has control that points into the peeled region.
3014 // This necessary because the cloned peeled region will be outside
3015 // the loop.
3016 // from to
3017 // cloned-peeled <---+
3018 // new_head_clone: | <--+
3019 // cloned-not_peeled in(0) in(0)
3020 // orig-peeled
3021
3022 for(i = 0; i < loop->_body.size(); i++ ) {
3023 Node *n = loop->_body.at(i);
3024 if (!n->is_CFG() && n->in(0) != NULL &&
3025 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3026 Node* n_clone = old_new[n->_idx];
3027 _igvn.replace_input_of(n_clone, 0, new_head_clone);
3028 }
3029 }
3030
3031 // Backedge of the surviving new_head (the clone) is original last_peel
3032 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3033
3034 // Cut first node in original not_peel set
3035 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
3036 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
3037 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
3038
3039 // Copy head_clone back-branch info to original head
3040 // and remove original head's loop entry and
3041 // clone head's back-branch
3042 _igvn.rehash_node_delayed(head); // Multiple edge updates
3043 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
3044 head->set_req(LoopNode::LoopBackControl, C->top());
3045 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3046
3047 // Similarly modify the phis
3048 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3049 Node* use = head->fast_out(k);
3050 if (use->is_Phi() && use->outcnt() > 0) {
3051 Node* use_clone = old_new[use->_idx];
3052 _igvn.rehash_node_delayed(use); // Multiple edge updates
3053 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
3054 use->set_req(LoopNode::LoopBackControl, C->top());
3055 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3056 }
3057 }
3058
3059 // Step 4: update dominator tree and dominator depth
3060
3061 set_idom(head, orig_tail_clone, dd);
3062 recompute_dom_depth();
3063
3064 // Inhibit more partial peeling on this loop
3065 new_head_clone->set_partial_peel_loop();
3066 C->set_major_progress();
3067 loop->record_for_igvn();
3068
3069 #if !defined(PRODUCT)
3070 if (TracePartialPeeling) {
3071 tty->print_cr("\nafter partial peel one iteration");
3072 Node_List wl(area);
3073 Node* t = last_peel;
3074 while (true) {
3075 wl.push(t);
3076 if (t == head_clone) break;
3077 t = idom(t);
3078 }
3079 while (wl.size() > 0) {
3080 Node* tt = wl.pop();
3081 if (tt == head) tty->print_cr("orig head");
3082 else if (tt == new_head_clone) tty->print_cr("new head");
3083 else if (tt == head_clone) tty->print_cr("clone head");
3084 tt->dump();
3085 }
3086 }
3087 #endif
3088 return true;
3089 }
3090
3091 //------------------------------reorg_offsets----------------------------------
3092 // Reorganize offset computations to lower register pressure. Mostly
3093 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3094 // then alive with the post-incremented trip counter forcing an extra
3095 // register move)
3096 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3097 // Perform it only for canonical counted loops.
3098 // Loop's shape could be messed up by iteration_split_impl.
3099 if (!loop->_head->is_CountedLoop())
3100 return;
3101 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3102 return;
3103
3104 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3105 CountedLoopEndNode *cle = cl->loopexit();
3106 Node *exit = cle->proj_out(false);
3107 Node *phi = cl->phi();
3108
3109 // Check for the special case of folks using the pre-incremented
3110 // trip-counter on the fall-out path (forces the pre-incremented
3111 // and post-incremented trip counter to be live at the same time).
3112 // Fix this by adjusting to use the post-increment trip counter.
3113
3114 bool progress = true;
3115 while (progress) {
3116 progress = false;
3117 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3118 Node* use = phi->fast_out(i); // User of trip-counter
3119 if (!has_ctrl(use)) continue;
3120 Node *u_ctrl = get_ctrl(use);
3121 if (use->is_Phi()) {
3122 u_ctrl = NULL;
3123 for (uint j = 1; j < use->req(); j++)
3124 if (use->in(j) == phi)
3125 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3126 }
3127 IdealLoopTree *u_loop = get_loop(u_ctrl);
3128 // Look for loop-invariant use
3129 if (u_loop == loop) continue;
3130 if (loop->is_member(u_loop)) continue;
3131 // Check that use is live out the bottom. Assuming the trip-counter
3132 // update is right at the bottom, uses of of the loop middle are ok.
3133 if (dom_lca(exit, u_ctrl) != exit) continue;
3134 // Hit! Refactor use to use the post-incremented tripcounter.
3135 // Compute a post-increment tripcounter.
3136 Node *opaq = new Opaque2Node( C, cle->incr() );
3137 register_new_node(opaq, exit);
3138 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3139 set_ctrl(neg_stride, C->root());
3140 Node *post = new AddINode( opaq, neg_stride);
3141 register_new_node(post, exit);
3142 _igvn.rehash_node_delayed(use);
3143 for (uint j = 1; j < use->req(); j++) {
3144 if (use->in(j) == phi)
3145 use->set_req(j, post);
3146 }
3147 // Since DU info changed, rerun loop
3148 progress = true;
3149 break;
3150 }
3151 }
3152
3153 }