1 /*
2 * Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/castnode.hpp"
30 #include "opto/connode.hpp"
31 #include "opto/castnode.hpp"
32 #include "opto/divnode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/matcher.hpp"
35 #include "opto/mulnode.hpp"
36 #include "opto/movenode.hpp"
37 #include "opto/opaquenode.hpp"
38 #include "opto/rootnode.hpp"
39 #include "opto/subnode.hpp"
40
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 int wins = 0;
60 assert(!n->is_CFG(), "");
61 assert(region->is_Region(), "");
62
63 const Type* type = n->bottom_type();
64 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
65 Node *phi;
66 if (t_oop != NULL && t_oop->is_known_instance_field()) {
67 int iid = t_oop->instance_id();
68 int index = C->get_alias_index(t_oop);
69 int offset = t_oop->offset();
70 phi = new PhiNode(region, type, NULL, iid, index, offset);
71 } else {
72 phi = PhiNode::make_blank(region, n);
73 }
74 uint old_unique = C->unique();
75 for (uint i = 1; i < region->req(); i++) {
76 Node *x;
77 Node* the_clone = NULL;
78 if (region->in(i) == C->top()) {
79 x = C->top(); // Dead path? Use a dead data op
80 } else {
81 x = n->clone(); // Else clone up the data op
82 the_clone = x; // Remember for possible deletion.
83 // Alter data node to use pre-phi inputs
84 if (n->in(0) == region)
85 x->set_req( 0, region->in(i) );
86 for (uint j = 1; j < n->req(); j++) {
87 Node *in = n->in(j);
88 if (in->is_Phi() && in->in(0) == region)
89 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
90 }
91 }
92 // Check for a 'win' on some paths
93 const Type *t = x->Value(&_igvn);
94
95 bool singleton = t->singleton();
96
97 // A TOP singleton indicates that there are no possible values incoming
98 // along a particular edge. In most cases, this is OK, and the Phi will
99 // be eliminated later in an Ideal call. However, we can't allow this to
100 // happen if the singleton occurs on loop entry, as the elimination of
101 // the PhiNode may cause the resulting node to migrate back to a previous
102 // loop iteration.
103 if (singleton && t == Type::TOP) {
104 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
105 // irreducible loop may not be indicated by an affirmative is_Loop());
106 // therefore, the only top we can split thru a phi is on a backedge of
107 // a loop.
108 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
109 }
110
111 if (singleton) {
112 wins++;
113 x = ((PhaseGVN&)_igvn).makecon(t);
114 } else {
115 // We now call Identity to try to simplify the cloned node.
116 // Note that some Identity methods call phase->type(this).
117 // Make sure that the type array is big enough for
118 // our new node, even though we may throw the node away.
119 // (Note: This tweaking with igvn only works because x is a new node.)
120 _igvn.set_type(x, t);
121 // If x is a TypeNode, capture any more-precise type permanently into Node
122 // otherwise it will be not updated during igvn->transform since
123 // igvn->type(x) is set to x->Value() already.
124 x->raise_bottom_type(t);
125 Node *y = x->Identity(&_igvn);
126 if (y != x) {
127 wins++;
128 x = y;
129 } else {
130 y = _igvn.hash_find(x);
131 if (y) {
132 wins++;
133 x = y;
134 } else {
135 // Else x is a new node we are keeping
136 // We do not need register_new_node_with_optimizer
137 // because set_type has already been called.
138 _igvn._worklist.push(x);
139 }
140 }
141 }
142 if (x != the_clone && the_clone != NULL)
143 _igvn.remove_dead_node(the_clone);
144 phi->set_req( i, x );
145 }
146 // Too few wins?
147 if (wins <= policy) {
148 _igvn.remove_dead_node(phi);
149 return NULL;
150 }
151
152 // Record Phi
153 register_new_node( phi, region );
154
155 for (uint i2 = 1; i2 < phi->req(); i2++) {
156 Node *x = phi->in(i2);
157 // If we commoned up the cloned 'x' with another existing Node,
158 // the existing Node picks up a new use. We need to make the
159 // existing Node occur higher up so it dominates its uses.
160 Node *old_ctrl;
161 IdealLoopTree *old_loop;
162
163 if (x->is_Con()) {
164 // Constant's control is always root.
165 set_ctrl(x, C->root());
166 continue;
167 }
168 // The occasional new node
169 if (x->_idx >= old_unique) { // Found a new, unplaced node?
170 old_ctrl = NULL;
171 old_loop = NULL; // Not in any prior loop
172 } else {
173 old_ctrl = get_ctrl(x);
174 old_loop = get_loop(old_ctrl); // Get prior loop
175 }
176 // New late point must dominate new use
177 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
178 if (new_ctrl == old_ctrl) // Nothing is changed
179 continue;
180
181 IdealLoopTree *new_loop = get_loop(new_ctrl);
182
183 // Don't move x into a loop if its uses are
184 // outside of loop. Otherwise x will be cloned
185 // for each use outside of this loop.
186 IdealLoopTree *use_loop = get_loop(region);
187 if (!new_loop->is_member(use_loop) &&
188 (old_loop == NULL || !new_loop->is_member(old_loop))) {
189 // Take early control, later control will be recalculated
190 // during next iteration of loop optimizations.
191 new_ctrl = get_early_ctrl(x);
192 new_loop = get_loop(new_ctrl);
193 }
194 // Set new location
195 set_ctrl(x, new_ctrl);
196 // If changing loop bodies, see if we need to collect into new body
197 if (old_loop != new_loop) {
198 if (old_loop && !old_loop->_child)
199 old_loop->_body.yank(x);
200 if (!new_loop->_child)
201 new_loop->_body.push(x); // Collect body info
202 }
203 }
204
205 return phi;
206 }
207
208 //------------------------------dominated_by------------------------------------
209 // Replace the dominated test with an obvious true or false. Place it on the
210 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
211 // live path up to the dominating control.
212 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
213 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
214
215 // prevdom is the dominating projection of the dominating test.
216 assert( iff->is_If(), "" );
217 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
218 int pop = prevdom->Opcode();
219 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
220 if (flip) {
221 if (pop == Op_IfTrue)
222 pop = Op_IfFalse;
223 else
224 pop = Op_IfTrue;
225 }
226 // 'con' is set to true or false to kill the dominated test.
227 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
228 set_ctrl(con, C->root()); // Constant gets a new use
229 // Hack the dominated test
230 _igvn.replace_input_of(iff, 1, con);
231
232 // If I dont have a reachable TRUE and FALSE path following the IfNode then
233 // I can assume this path reaches an infinite loop. In this case it's not
234 // important to optimize the data Nodes - either the whole compilation will
235 // be tossed or this path (and all data Nodes) will go dead.
236 if (iff->outcnt() != 2) return;
237
238 // Make control-dependent data Nodes on the live path (path that will remain
239 // once the dominated IF is removed) become control-dependent on the
240 // dominating projection.
241 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
242
243 // Loop predicates may have depending checks which should not
244 // be skipped. For example, range check predicate has two checks
245 // for lower and upper bounds.
246 if (dp == NULL)
247 return;
248
249 ProjNode* dp_proj = dp->as_Proj();
250 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
251 if (exclude_loop_predicate &&
252 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
253 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
254 // If this is a range check (IfNode::is_range_check), do not
255 // reorder because Compile::allow_range_check_smearing might have
256 // changed the check.
257 return; // Let IGVN transformation change control dependence.
258 }
259
260 IdealLoopTree *old_loop = get_loop(dp);
261
262 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
263 Node* cd = dp->fast_out(i); // Control-dependent node
264 if (cd->depends_only_on_test()) {
265 assert(cd->in(0) == dp, "");
266 _igvn.replace_input_of(cd, 0, prevdom);
267 set_early_ctrl(cd);
268 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
269 if (old_loop != new_loop) {
270 if (!old_loop->_child) old_loop->_body.yank(cd);
271 if (!new_loop->_child) new_loop->_body.push(cd);
272 }
273 --i;
274 --imax;
275 }
276 }
277 }
278
279 //------------------------------has_local_phi_input----------------------------
280 // Return TRUE if 'n' has Phi inputs from its local block and no other
281 // block-local inputs (all non-local-phi inputs come from earlier blocks)
282 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
283 Node *n_ctrl = get_ctrl(n);
284 // See if some inputs come from a Phi in this block, or from before
285 // this block.
286 uint i;
287 for( i = 1; i < n->req(); i++ ) {
288 Node *phi = n->in(i);
289 if( phi->is_Phi() && phi->in(0) == n_ctrl )
290 break;
291 }
292 if( i >= n->req() )
293 return NULL; // No Phi inputs; nowhere to clone thru
294
295 // Check for inputs created between 'n' and the Phi input. These
296 // must split as well; they have already been given the chance
297 // (courtesy of a post-order visit) and since they did not we must
298 // recover the 'cost' of splitting them by being very profitable
299 // when splitting 'n'. Since this is unlikely we simply give up.
300 for( i = 1; i < n->req(); i++ ) {
301 Node *m = n->in(i);
302 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
303 // We allow the special case of AddP's with no local inputs.
304 // This allows us to split-up address expressions.
305 if (m->is_AddP() &&
306 get_ctrl(m->in(2)) != n_ctrl &&
307 get_ctrl(m->in(3)) != n_ctrl) {
308 // Move the AddP up to dominating point
309 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
310 continue;
311 }
312 return NULL;
313 }
314 }
315
316 return n_ctrl;
317 }
318
319 //------------------------------remix_address_expressions----------------------
320 // Rework addressing expressions to get the most loop-invariant stuff
321 // moved out. We'd like to do all associative operators, but it's especially
322 // important (common) to do address expressions.
323 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
324 if (!has_ctrl(n)) return NULL;
325 Node *n_ctrl = get_ctrl(n);
326 IdealLoopTree *n_loop = get_loop(n_ctrl);
327
328 // See if 'n' mixes loop-varying and loop-invariant inputs and
329 // itself is loop-varying.
330
331 // Only interested in binary ops (and AddP)
332 if( n->req() < 3 || n->req() > 4 ) return NULL;
333
334 Node *n1_ctrl = get_ctrl(n->in( 1));
335 Node *n2_ctrl = get_ctrl(n->in( 2));
336 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
337 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
338 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
339 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
340
341 // Does one of my inputs spin in a tighter loop than self?
342 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
343 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
344 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
345 return NULL; // Leave well enough alone
346
347 // Is at least one of my inputs loop-invariant?
348 if( n1_loop == n_loop &&
349 n2_loop == n_loop &&
350 n3_loop == n_loop )
351 return NULL; // No loop-invariant inputs
352
353
354 int n_op = n->Opcode();
355
356 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
357 if( n_op == Op_LShiftI ) {
358 // Scale is loop invariant
359 Node *scale = n->in(2);
360 Node *scale_ctrl = get_ctrl(scale);
361 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
362 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
363 return NULL;
364 const TypeInt *scale_t = scale->bottom_type()->isa_int();
365 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
366 return NULL; // Dont bother with byte/short masking
367 // Add must vary with loop (else shift would be loop-invariant)
368 Node *add = n->in(1);
369 Node *add_ctrl = get_ctrl(add);
370 IdealLoopTree *add_loop = get_loop(add_ctrl);
371 //assert( n_loop == add_loop, "" );
372 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
373
374 // Convert I-V into I+ (0-V); same for V-I
375 if( add->Opcode() == Op_SubI &&
376 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
377 Node *zero = _igvn.intcon(0);
378 set_ctrl(zero, C->root());
379 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
380 register_new_node( neg, get_ctrl(add->in(2) ) );
381 add = new AddINode( add->in(1), neg );
382 register_new_node( add, add_ctrl );
383 }
384 if( add->Opcode() != Op_AddI ) return NULL;
385 // See if one add input is loop invariant
386 Node *add_var = add->in(1);
387 Node *add_var_ctrl = get_ctrl(add_var);
388 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
389 Node *add_invar = add->in(2);
390 Node *add_invar_ctrl = get_ctrl(add_invar);
391 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
392 if( add_var_loop == n_loop ) {
393 } else if( add_invar_loop == n_loop ) {
394 // Swap to find the invariant part
395 add_invar = add_var;
396 add_invar_ctrl = add_var_ctrl;
397 add_invar_loop = add_var_loop;
398 add_var = add->in(2);
399 Node *add_var_ctrl = get_ctrl(add_var);
400 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
401 } else // Else neither input is loop invariant
402 return NULL;
403 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
404 return NULL; // No invariant part of the add?
405
406 // Yes! Reshape address expression!
407 Node *inv_scale = new LShiftINode( add_invar, scale );
408 Node *inv_scale_ctrl =
409 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
410 add_invar_ctrl : scale_ctrl;
411 register_new_node( inv_scale, inv_scale_ctrl );
412 Node *var_scale = new LShiftINode( add_var, scale );
413 register_new_node( var_scale, n_ctrl );
414 Node *var_add = new AddINode( var_scale, inv_scale );
415 register_new_node( var_add, n_ctrl );
416 _igvn.replace_node( n, var_add );
417 return var_add;
418 }
419
420 // Replace (I+V) with (V+I)
421 if( n_op == Op_AddI ||
422 n_op == Op_AddL ||
423 n_op == Op_AddF ||
424 n_op == Op_AddD ||
425 n_op == Op_MulI ||
426 n_op == Op_MulL ||
427 n_op == Op_MulF ||
428 n_op == Op_MulD ) {
429 if( n2_loop == n_loop ) {
430 assert( n1_loop != n_loop, "" );
431 n->swap_edges(1, 2);
432 }
433 }
434
435 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
436 // but not if I2 is a constant.
437 if( n_op == Op_AddP ) {
438 if( n2_loop == n_loop && n3_loop != n_loop ) {
439 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
440 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
441 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
442 IdealLoopTree *n22loop = get_loop( n22_ctrl );
443 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
444 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
445 n23_loop == n_loop ) {
446 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
447 // Stuff new AddP in the loop preheader
448 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
449 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
450 register_new_node( add2, n_ctrl );
451 _igvn.replace_node( n, add2 );
452 return add2;
453 }
454 }
455 }
456
457 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
458 if (n2_loop != n_loop && n3_loop == n_loop) {
459 if (n->in(3)->Opcode() == Op_AddX) {
460 Node *V = n->in(3)->in(1);
461 Node *I = n->in(3)->in(2);
462 if (is_member(n_loop,get_ctrl(V))) {
463 } else {
464 Node *tmp = V; V = I; I = tmp;
465 }
466 if (!is_member(n_loop,get_ctrl(I))) {
467 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
468 // Stuff new AddP in the loop preheader
469 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
470 Node *add2 = new AddPNode(n->in(1), add1, V);
471 register_new_node(add2, n_ctrl);
472 _igvn.replace_node(n, add2);
473 return add2;
474 }
475 }
476 }
477 }
478
479 return NULL;
480 }
481
482 //------------------------------conditional_move-------------------------------
483 // Attempt to replace a Phi with a conditional move. We have some pretty
484 // strict profitability requirements. All Phis at the merge point must
485 // be converted, so we can remove the control flow. We need to limit the
486 // number of c-moves to a small handful. All code that was in the side-arms
487 // of the CFG diamond is now speculatively executed. This code has to be
488 // "cheap enough". We are pretty much limited to CFG diamonds that merge
489 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
490 Node *PhaseIdealLoop::conditional_move( Node *region ) {
491
492 assert(region->is_Region(), "sanity check");
493 if (region->req() != 3) return NULL;
494
495 // Check for CFG diamond
496 Node *lp = region->in(1);
497 Node *rp = region->in(2);
498 if (!lp || !rp) return NULL;
499 Node *lp_c = lp->in(0);
500 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
501 IfNode *iff = lp_c->as_If();
502
503 // Check for ops pinned in an arm of the diamond.
504 // Can't remove the control flow in this case
505 if (lp->outcnt() > 1) return NULL;
506 if (rp->outcnt() > 1) return NULL;
507
508 IdealLoopTree* r_loop = get_loop(region);
509 assert(r_loop == get_loop(iff), "sanity");
510 // Always convert to CMOVE if all results are used only outside this loop.
511 bool used_inside_loop = (r_loop == _ltree_root);
512
513 // Check profitability
514 int cost = 0;
515 int phis = 0;
516 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
517 Node *out = region->fast_out(i);
518 if (!out->is_Phi()) continue; // Ignore other control edges, etc
519 phis++;
520 PhiNode* phi = out->as_Phi();
521 BasicType bt = phi->type()->basic_type();
522 switch (bt) {
523 case T_DOUBLE:
524 if (C->use_cmove()) {
525 continue; //TODO: maybe we want to add some cost
526 }
527 case T_FLOAT: {
528 cost += Matcher::float_cmove_cost(); // Could be very expensive
529 break;
530 }
531 case T_LONG: {
532 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
533 }
534 case T_INT: // These all CMOV fine
535 case T_ADDRESS: { // (RawPtr)
536 cost++;
537 break;
538 }
539 case T_NARROWOOP: // Fall through
540 case T_OBJECT: { // Base oops are OK, but not derived oops
541 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
542 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
543 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
544 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
545 // have a Phi for the base here that we convert to a CMOVE all is well
546 // and good. But if the base is dead, we'll not make a CMOVE. Later
547 // the allocator will have to produce a base by creating a CMOVE of the
548 // relevant bases. This puts the allocator in the business of
549 // manufacturing expensive instructions, generally a bad plan.
550 // Just Say No to Conditionally-Moved Derived Pointers.
551 if (tp && tp->offset() != 0)
552 return NULL;
553 cost++;
554 break;
555 }
556 default:
557 return NULL; // In particular, can't do memory or I/O
558 }
559 // Add in cost any speculative ops
560 for (uint j = 1; j < region->req(); j++) {
561 Node *proj = region->in(j);
562 Node *inp = phi->in(j);
563 if (get_ctrl(inp) == proj) { // Found local op
564 cost++;
565 // Check for a chain of dependent ops; these will all become
566 // speculative in a CMOV.
567 for (uint k = 1; k < inp->req(); k++)
568 if (get_ctrl(inp->in(k)) == proj)
569 cost += ConditionalMoveLimit; // Too much speculative goo
570 }
571 }
572 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
573 // This will likely Split-If, a higher-payoff operation.
574 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
575 Node* use = phi->fast_out(k);
576 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
577 cost += ConditionalMoveLimit;
578 // Is there a use inside the loop?
579 // Note: check only basic types since CMoveP is pinned.
580 if (!used_inside_loop && is_java_primitive(bt)) {
581 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
582 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
583 used_inside_loop = true;
584 }
585 }
586 }
587 }//for
588 Node* bol = iff->in(1);
589 assert(bol->Opcode() == Op_Bool, "");
590 int cmp_op = bol->in(1)->Opcode();
591 // It is expensive to generate flags from a float compare.
592 // Avoid duplicated float compare.
593 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
594
595 float infrequent_prob = PROB_UNLIKELY_MAG(3);
596 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
597 if (used_inside_loop) {
598 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
599
600 // BlockLayoutByFrequency optimization moves infrequent branch
601 // from hot path. No point in CMOV'ing in such case (110 is used
602 // instead of 100 to take into account not exactness of float value).
603 if (BlockLayoutByFrequency) {
604 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
605 }
606 }
607 // Check for highly predictable branch. No point in CMOV'ing if
608 // we are going to predict accurately all the time.
609 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
610 else if (iff->_prob < infrequent_prob ||
611 iff->_prob > (1.0f - infrequent_prob))
612 return NULL;
613
614 // --------------
615 // Now replace all Phis with CMOV's
616 Node *cmov_ctrl = iff->in(0);
617 uint flip = (lp->Opcode() == Op_IfTrue);
618 while (1) {
619 PhiNode* phi = NULL;
620 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
621 Node *out = region->fast_out(i);
622 if (out->is_Phi()) {
623 phi = out->as_Phi();
624 break;
625 }
626 }
627 if (phi == NULL) break;
628 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
629 // Move speculative ops
630 for (uint j = 1; j < region->req(); j++) {
631 Node *proj = region->in(j);
632 Node *inp = phi->in(j);
633 if (get_ctrl(inp) == proj) { // Found local op
634 #ifndef PRODUCT
635 if (PrintOpto && VerifyLoopOptimizations) {
636 tty->print(" speculate: ");
637 inp->dump();
638 }
639 #endif
640 set_ctrl(inp, cmov_ctrl);
641 }
642 }
643 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
644 register_new_node( cmov, cmov_ctrl );
645 _igvn.replace_node( phi, cmov );
646 #ifndef PRODUCT
647 if (TraceLoopOpts) {
648 tty->print("CMOV ");
649 r_loop->dump_head();
650 if (Verbose) {
651 bol->in(1)->dump(1);
652 cmov->dump(1);
653 }
654 }
655 if (VerifyLoopOptimizations) verify();
656 #endif
657 }
658
659 // The useless CFG diamond will fold up later; see the optimization in
660 // RegionNode::Ideal.
661 _igvn._worklist.push(region);
662
663 return iff->in(1);
664 }
665
666 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
667 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
668 Node* u = m->fast_out(i);
669 if (u->is_CFG()) {
670 if (u->Opcode() == Op_NeverBranch) {
671 u = ((NeverBranchNode*)u)->proj_out(0);
672 enqueue_cfg_uses(u, wq);
673 } else {
674 wq.push(u);
675 }
676 }
677 }
678 }
679
680 // Try moving a store out of a loop, right before the loop
681 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
682 // Store has to be first in the loop body
683 IdealLoopTree *n_loop = get_loop(n_ctrl);
684 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
685 Node* address = n->in(MemNode::Address);
686 Node* value = n->in(MemNode::ValueIn);
687 Node* mem = n->in(MemNode::Memory);
688 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
689 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
690
691 // - address and value must be loop invariant
692 // - memory must be a memory Phi for the loop
693 // - Store must be the only store on this memory slice in the
694 // loop: if there's another store following this one then value
695 // written at iteration i by the second store could be overwritten
696 // at iteration i+n by the first store: it's not safe to move the
697 // first store out of the loop
698 // - nothing must observe the memory Phi: it guarantees no read
699 // before the store, we are also guaranteed the store post
700 // dominates the loop head (ignoring a possible early
701 // exit). Otherwise there would be extra Phi involved between the
702 // loop's Phi and the store.
703 // - there must be no early exit from the loop before the Store
704 // (such an exit most of the time would be an extra use of the
705 // memory Phi but sometimes is a bottom memory Phi that takes the
706 // store as input).
707
708 if (!n_loop->is_member(address_loop) &&
709 !n_loop->is_member(value_loop) &&
710 mem->is_Phi() && mem->in(0) == n_loop->_head &&
711 mem->outcnt() == 1 &&
712 mem->in(LoopNode::LoopBackControl) == n) {
713
714 assert(n_loop->_tail != NULL, "need a tail");
715 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
716
717 // Verify that there's no early exit of the loop before the store.
718 bool ctrl_ok = false;
719 {
720 // Follow control from loop head until n, we exit the loop or
721 // we reach the tail
722 ResourceMark rm;
723 Unique_Node_List wq;
724 wq.push(n_loop->_head);
725
726 for (uint next = 0; next < wq.size(); ++next) {
727 Node *m = wq.at(next);
728 if (m == n->in(0)) {
729 ctrl_ok = true;
730 continue;
731 }
732 assert(!has_ctrl(m), "should be CFG");
733 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
734 ctrl_ok = false;
735 break;
736 }
737 enqueue_cfg_uses(m, wq);
738 if (wq.size() > 10) {
739 ctrl_ok = false;
740 break;
741 }
742 }
743 }
744 if (ctrl_ok) {
745 // move the Store
746 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
747 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
748 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
749 // Disconnect the phi now. An empty phi can confuse other
750 // optimizations in this pass of loop opts.
751 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
752 n_loop->_body.yank(mem);
753
754 IdealLoopTree* new_loop = get_loop(n->in(0));
755 set_ctrl_and_loop(n, n->in(0));
756
757 return n;
758 }
759 }
760 }
761 return NULL;
762 }
763
764 // Try moving a store out of a loop, right after the loop
765 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
766 if (n->is_Store() && n->in(0) != NULL) {
767 Node *n_ctrl = get_ctrl(n);
768 IdealLoopTree *n_loop = get_loop(n_ctrl);
769 // Store must be in a loop
770 if (n_loop != _ltree_root && !n_loop->_irreducible) {
771 Node* address = n->in(MemNode::Address);
772 Node* value = n->in(MemNode::ValueIn);
773 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
774 // address must be loop invariant
775 if (!n_loop->is_member(address_loop)) {
776 // Store must be last on this memory slice in the loop and
777 // nothing in the loop must observe it
778 Node* phi = NULL;
779 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
780 Node* u = n->fast_out(i);
781 if (has_ctrl(u)) { // control use?
782 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
783 if (!n_loop->is_member(u_loop)) {
784 continue;
785 }
786 if (u->is_Phi() && u->in(0) == n_loop->_head) {
787 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
788 // multiple phis on the same slice are possible
789 if (phi != NULL) {
790 return;
791 }
792 phi = u;
793 continue;
794 }
795 }
796 return;
797 }
798 if (phi != NULL) {
799 // Nothing in the loop before the store (next iteration)
800 // must observe the stored value
801 bool mem_ok = true;
802 {
803 ResourceMark rm;
804 Unique_Node_List wq;
805 wq.push(phi);
806 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
807 Node *m = wq.at(next);
808 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
809 Node* u = m->fast_out(i);
810 if (u->is_Store() || u->is_Phi()) {
811 if (u != n) {
812 wq.push(u);
813 mem_ok = (wq.size() <= 10);
814 }
815 } else {
816 mem_ok = false;
817 break;
818 }
819 }
820 }
821 }
822 if (mem_ok) {
823 // Move the Store out of the loop creating clones along
824 // all paths out of the loop that observe the stored value
825 _igvn.rehash_node_delayed(phi);
826 int count = phi->replace_edge(n, n->in(MemNode::Memory));
827 assert(count > 0, "inconsistent phi");
828 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
829 Node* u = n->fast_out(i);
830 Node* c = get_ctrl(u);
831
832 if (u->is_Phi()) {
833 c = u->in(0)->in(u->find_edge(n));
834 }
835 IdealLoopTree *u_loop = get_loop(c);
836 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
837 while(true) {
838 Node* next_c = find_non_split_ctrl(idom(c));
839 if (n_loop->is_member(get_loop(next_c))) {
840 break;
841 }
842 c = next_c;
843 }
844
845 Node* st = n->clone();
846 st->set_req(0, c);
847 _igvn.register_new_node_with_optimizer(st);
848
849 set_ctrl(st, c);
850 IdealLoopTree* new_loop = get_loop(c);
851 assert(new_loop != n_loop, "should be moved out of loop");
852 if (new_loop->_child == NULL) new_loop->_body.push(st);
853
854 _igvn.replace_input_of(u, u->find_edge(n), st);
855 --imax;
856 --i;
857 }
858
859
860 assert(n->outcnt() == 0, "all uses should be gone");
861 _igvn.replace_input_of(n, MemNode::Memory, C->top());
862 // Disconnect the phi now. An empty phi can confuse other
863 // optimizations in this pass of loop opts..
864 if (phi->in(LoopNode::LoopBackControl) == phi) {
865 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
866 n_loop->_body.yank(phi);
867 }
868 }
869 }
870 }
871 }
872 }
873 }
874
875 //------------------------------split_if_with_blocks_pre-----------------------
876 // Do the real work in a non-recursive function. Data nodes want to be
877 // cloned in the pre-order so they can feed each other nicely.
878 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
879 // Cloning these guys is unlikely to win
880 int n_op = n->Opcode();
881 if( n_op == Op_MergeMem ) return n;
882 if( n->is_Proj() ) return n;
883 // Do not clone-up CmpFXXX variations, as these are always
884 // followed by a CmpI
885 if( n->is_Cmp() ) return n;
886 // Attempt to use a conditional move instead of a phi/branch
887 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
888 Node *cmov = conditional_move( n );
889 if( cmov ) return cmov;
890 }
891 if( n->is_CFG() || n->is_LoadStore() )
892 return n;
893 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
894 n_op == Op_Opaque2 ) {
895 if( !C->major_progress() ) // If chance of no more loop opts...
896 _igvn._worklist.push(n); // maybe we'll remove them
897 return n;
898 }
899
900 if( n->is_Con() ) return n; // No cloning for Con nodes
901
902 Node *n_ctrl = get_ctrl(n);
903 if( !n_ctrl ) return n; // Dead node
904
905 Node* res = try_move_store_before_loop(n, n_ctrl);
906 if (res != NULL) {
907 return n;
908 }
909
910 // Attempt to remix address expressions for loop invariants
911 Node *m = remix_address_expressions( n );
912 if( m ) return m;
913
914 if (n->is_ConstraintCast()) {
915 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
916 // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
917 // Node control inputs don't necessarily agree with loop control info (due to
918 // transformations happened in between), thus additional dominance check is needed
919 // to keep loop info valid.
920 if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
921 _igvn.replace_node(n, dom_cast);
922 return dom_cast;
923 }
924 }
925
926 // Determine if the Node has inputs from some local Phi.
927 // Returns the block to clone thru.
928 Node *n_blk = has_local_phi_input( n );
929 if( !n_blk ) return n;
930
931 // Do not clone the trip counter through on a CountedLoop
932 // (messes up the canonical shape).
933 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
934
935 // Check for having no control input; not pinned. Allow
936 // dominating control.
937 if (n->in(0)) {
938 Node *dom = idom(n_blk);
939 if (dom_lca(n->in(0), dom) != n->in(0)) {
940 return n;
941 }
942 }
943 // Policy: when is it profitable. You must get more wins than
944 // policy before it is considered profitable. Policy is usually 0,
945 // so 1 win is considered profitable. Big merges will require big
946 // cloning, so get a larger policy.
947 int policy = n_blk->req() >> 2;
948
949 // If the loop is a candidate for range check elimination,
950 // delay splitting through it's phi until a later loop optimization
951 if (n_blk->is_CountedLoop()) {
952 IdealLoopTree *lp = get_loop(n_blk);
953 if (lp && lp->_rce_candidate) {
954 return n;
955 }
956 }
957
958 // Use same limit as split_if_with_blocks_post
959 if( C->live_nodes() > 35000 ) return n; // Method too big
960
961 // Split 'n' through the merge point if it is profitable
962 Node *phi = split_thru_phi( n, n_blk, policy );
963 if (!phi) return n;
964
965 // Found a Phi to split thru!
966 // Replace 'n' with the new phi
967 _igvn.replace_node( n, phi );
968 // Moved a load around the loop, 'en-registering' something.
969 if (n_blk->is_Loop() && n->is_Load() &&
970 !phi->in(LoopNode::LoopBackControl)->is_Load())
971 C->set_major_progress();
972
973 return phi;
974 }
975
976 static bool merge_point_too_heavy(Compile* C, Node* region) {
977 // Bail out if the region and its phis have too many users.
978 int weight = 0;
979 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
980 weight += region->fast_out(i)->outcnt();
981 }
982 int nodes_left = C->max_node_limit() - C->live_nodes();
983 if (weight * 8 > nodes_left) {
984 if (PrintOpto) {
985 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
986 }
987 return true;
988 } else {
989 return false;
990 }
991 }
992
993 static bool merge_point_safe(Node* region) {
994 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
995 // having a PhiNode input. This sidesteps the dangerous case where the split
996 // ConvI2LNode may become TOP if the input Value() does not
997 // overlap the ConvI2L range, leaving a node which may not dominate its
998 // uses.
999 // A better fix for this problem can be found in the BugTraq entry, but
1000 // expediency for Mantis demands this hack.
1001 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1002 // split_if_with_blocks from splitting a block because we could not move around
1003 // the FastLockNode.
1004 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1005 Node* n = region->fast_out(i);
1006 if (n->is_Phi()) {
1007 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1008 Node* m = n->fast_out(j);
1009 if (m->is_FastLock())
1010 return false;
1011 #ifdef _LP64
1012 if (m->Opcode() == Op_ConvI2L)
1013 return false;
1014 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1015 return false;
1016 }
1017 #endif
1018 }
1019 }
1020 }
1021 return true;
1022 }
1023
1024
1025 //------------------------------place_near_use---------------------------------
1026 // Place some computation next to use but not inside inner loops.
1027 // For inner loop uses move it to the preheader area.
1028 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1029 IdealLoopTree *u_loop = get_loop( useblock );
1030 return (u_loop->_irreducible || u_loop->_child)
1031 ? useblock
1032 : u_loop->_head->in(LoopNode::EntryControl);
1033 }
1034
1035
1036 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1037 if (!n->is_If()) {
1038 return false;
1039 }
1040 if (!n->in(0)->is_Region()) {
1041 return false;
1042 }
1043 Node* region = n->in(0);
1044 Node* dom = idom(region);
1045 if (!dom->is_If() || dom->in(1) != n->in(1)) {
1046 return false;
1047 }
1048 IfNode* dom_if = dom->as_If();
1049 Node* proj_true = dom_if->proj_out(1);
1050 Node* proj_false = dom_if->proj_out(0);
1051
1052 for (uint i = 1; i < region->req(); i++) {
1053 if (is_dominator(proj_true, region->in(i))) {
1054 continue;
1055 }
1056 if (is_dominator(proj_false, region->in(i))) {
1057 continue;
1058 }
1059 return false;
1060 }
1061
1062 return true;
1063 }
1064
1065 bool PhaseIdealLoop::can_split_if(Node *n_ctrl) {
1066 if (C->live_nodes() > 35000) {
1067 return false; // Method too big
1068 }
1069
1070 // Do not do 'split-if' if irreducible loops are present.
1071 if (_has_irreducible_loops) {
1072 return false;
1073 }
1074
1075 if (merge_point_too_heavy(C, n_ctrl)) {
1076 return false;
1077 }
1078
1079 // Do not do 'split-if' if some paths are dead. First do dead code
1080 // elimination and then see if its still profitable.
1081 for (uint i = 1; i < n_ctrl->req(); i++) {
1082 if (n_ctrl->in(i) == C->top()) {
1083 return false;
1084 }
1085 }
1086
1087 // If trying to do a 'Split-If' at the loop head, it is only
1088 // profitable if the cmp folds up on BOTH paths. Otherwise we
1089 // risk peeling a loop forever.
1090
1091 // CNC - Disabled for now. Requires careful handling of loop
1092 // body selection for the cloned code. Also, make sure we check
1093 // for any input path not being in the same loop as n_ctrl. For
1094 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1095 // because the alternative loop entry points won't be converted
1096 // into LoopNodes.
1097 IdealLoopTree *n_loop = get_loop(n_ctrl);
1098 for (uint j = 1; j < n_ctrl->req(); j++) {
1099 if (get_loop(n_ctrl->in(j)) != n_loop) {
1100 return false;
1101 }
1102 }
1103
1104 // Check for safety of the merge point.
1105 if (!merge_point_safe(n_ctrl)) {
1106 return false;
1107 }
1108
1109 return true;
1110 }
1111
1112 //------------------------------split_if_with_blocks_post----------------------
1113 // Do the real work in a non-recursive function. CFG hackery wants to be
1114 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1115 // info.
1116 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1117
1118 // Cloning Cmp through Phi's involves the split-if transform.
1119 // FastLock is not used by an If
1120 if (n->is_Cmp() && !n->is_FastLock()) {
1121 Node *n_ctrl = get_ctrl(n);
1122 // Determine if the Node has inputs from some local Phi.
1123 // Returns the block to clone thru.
1124 Node *n_blk = has_local_phi_input(n);
1125 if (n_blk != n_ctrl) {
1126 return;
1127 }
1128
1129 if (!can_split_if(n_ctrl)) {
1130 return;
1131 }
1132
1133 if (n->outcnt() != 1) {
1134 return; // Multiple bool's from 1 compare?
1135 }
1136 Node *bol = n->unique_out();
1137 assert(bol->is_Bool(), "expect a bool here");
1138 if (bol->outcnt() != 1) {
1139 return;// Multiple branches from 1 compare?
1140 }
1141 Node *iff = bol->unique_out();
1142
1143 // Check some safety conditions
1144 if (iff->is_If()) { // Classic split-if?
1145 if (iff->in(0) != n_ctrl) {
1146 return; // Compare must be in same blk as if
1147 }
1148 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1149 // Can't split CMove with different control edge.
1150 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1151 return;
1152 }
1153 if (get_ctrl(iff->in(2)) == n_ctrl ||
1154 get_ctrl(iff->in(3)) == n_ctrl) {
1155 return; // Inputs not yet split-up
1156 }
1157 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1158 return; // Loop-invar test gates loop-varying CMOVE
1159 }
1160 } else {
1161 return; // some other kind of node, such as an Allocate
1162 }
1163
1164 // When is split-if profitable? Every 'win' on means some control flow
1165 // goes dead, so it's almost always a win.
1166 int policy = 0;
1167 // Split compare 'n' through the merge point if it is profitable
1168 Node *phi = split_thru_phi( n, n_ctrl, policy);
1169 if (!phi) {
1170 return;
1171 }
1172
1173 // Found a Phi to split thru!
1174 // Replace 'n' with the new phi
1175 _igvn.replace_node(n, phi);
1176
1177 // Now split the bool up thru the phi
1178 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1179 guarantee(bolphi != NULL, "null boolean phi node");
1180
1181 _igvn.replace_node(bol, bolphi);
1182 assert(iff->in(1) == bolphi, "");
1183
1184 if (bolphi->Value(&_igvn)->singleton()) {
1185 return;
1186 }
1187
1188 // Conditional-move? Must split up now
1189 if (!iff->is_If()) {
1190 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1191 _igvn.replace_node(iff, cmovphi);
1192 return;
1193 }
1194
1195 // Now split the IF
1196 do_split_if(iff);
1197 return;
1198 }
1199
1200 // Two identical ifs back to back can be merged
1201 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1202 Node *n_ctrl = n->in(0);
1203 PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1204 IfNode* dom_if = idom(n_ctrl)->as_If();
1205 Node* proj_true = dom_if->proj_out(1);
1206 Node* proj_false = dom_if->proj_out(0);
1207 Node* con_true = _igvn.makecon(TypeInt::ONE);
1208 Node* con_false = _igvn.makecon(TypeInt::ZERO);
1209
1210 for (uint i = 1; i < n_ctrl->req(); i++) {
1211 if (is_dominator(proj_true, n_ctrl->in(i))) {
1212 bolphi->init_req(i, con_true);
1213 } else {
1214 assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1215 bolphi->init_req(i, con_false);
1216 }
1217 }
1218 register_new_node(bolphi, n_ctrl);
1219 _igvn.replace_input_of(n, 1, bolphi);
1220
1221 // Now split the IF
1222 do_split_if(n);
1223 return;
1224 }
1225
1226 // Check for an IF ready to split; one that has its
1227 // condition codes input coming from a Phi at the block start.
1228 int n_op = n->Opcode();
1229
1230 // Check for an IF being dominated by another IF same test
1231 if (n_op == Op_If ||
1232 n_op == Op_RangeCheck) {
1233 Node *bol = n->in(1);
1234 uint max = bol->outcnt();
1235 // Check for same test used more than once?
1236 if (max > 1 && bol->is_Bool()) {
1237 // Search up IDOMs to see if this IF is dominated.
1238 Node *cutoff = get_ctrl(bol);
1239
1240 // Now search up IDOMs till cutoff, looking for a dominating test
1241 Node *prevdom = n;
1242 Node *dom = idom(prevdom);
1243 while (dom != cutoff) {
1244 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1245 // Replace the dominated test with an obvious true or false.
1246 // Place it on the IGVN worklist for later cleanup.
1247 C->set_major_progress();
1248 dominated_by(prevdom, n, false, true);
1249 #ifndef PRODUCT
1250 if( VerifyLoopOptimizations ) verify();
1251 #endif
1252 return;
1253 }
1254 prevdom = dom;
1255 dom = idom(prevdom);
1256 }
1257 }
1258 }
1259
1260 // See if a shared loop-varying computation has no loop-varying uses.
1261 // Happens if something is only used for JVM state in uncommon trap exits,
1262 // like various versions of induction variable+offset. Clone the
1263 // computation per usage to allow it to sink out of the loop.
1264 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1265 Node *n_ctrl = get_ctrl(n);
1266 IdealLoopTree *n_loop = get_loop(n_ctrl);
1267 if( n_loop != _ltree_root ) {
1268 DUIterator_Fast imax, i = n->fast_outs(imax);
1269 for (; i < imax; i++) {
1270 Node* u = n->fast_out(i);
1271 if( !has_ctrl(u) ) break; // Found control user
1272 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1273 if( u_loop == n_loop ) break; // Found loop-varying use
1274 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1275 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1276 }
1277 bool did_break = (i < imax); // Did we break out of the previous loop?
1278 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1279 Node *late_load_ctrl = NULL;
1280 if (n->is_Load()) {
1281 // If n is a load, get and save the result from get_late_ctrl(),
1282 // to be later used in calculating the control for n's clones.
1283 clear_dom_lca_tags();
1284 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1285 }
1286 // If n is a load, and the late control is the same as the current
1287 // control, then the cloning of n is a pointless exercise, because
1288 // GVN will ensure that we end up where we started.
1289 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1290 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1291 Node *u = n->last_out(j); // Clone private computation per use
1292 _igvn.rehash_node_delayed(u);
1293 Node *x = n->clone(); // Clone computation
1294 Node *x_ctrl = NULL;
1295 if( u->is_Phi() ) {
1296 // Replace all uses of normal nodes. Replace Phi uses
1297 // individually, so the separate Nodes can sink down
1298 // different paths.
1299 uint k = 1;
1300 while( u->in(k) != n ) k++;
1301 u->set_req( k, x );
1302 // x goes next to Phi input path
1303 x_ctrl = u->in(0)->in(k);
1304 --j;
1305 } else { // Normal use
1306 // Replace all uses
1307 for( uint k = 0; k < u->req(); k++ ) {
1308 if( u->in(k) == n ) {
1309 u->set_req( k, x );
1310 --j;
1311 }
1312 }
1313 x_ctrl = get_ctrl(u);
1314 }
1315
1316 // Find control for 'x' next to use but not inside inner loops.
1317 // For inner loop uses get the preheader area.
1318 x_ctrl = place_near_use(x_ctrl);
1319
1320 if (n->is_Load()) {
1321 // For loads, add a control edge to a CFG node outside of the loop
1322 // to force them to not combine and return back inside the loop
1323 // during GVN optimization (4641526).
1324 //
1325 // Because we are setting the actual control input, factor in
1326 // the result from get_late_ctrl() so we respect any
1327 // anti-dependences. (6233005).
1328 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1329
1330 // Don't allow the control input to be a CFG splitting node.
1331 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1332 // should only have IfTrueNode and IfFalseNode (4985384).
1333 x_ctrl = find_non_split_ctrl(x_ctrl);
1334 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1335
1336 x->set_req(0, x_ctrl);
1337 }
1338 register_new_node(x, x_ctrl);
1339
1340 // Some institutional knowledge is needed here: 'x' is
1341 // yanked because if the optimizer runs GVN on it all the
1342 // cloned x's will common up and undo this optimization and
1343 // be forced back in the loop. This is annoying because it
1344 // makes +VerifyOpto report false-positives on progress. I
1345 // tried setting control edges on the x's to force them to
1346 // not combine, but the matching gets worried when it tries
1347 // to fold a StoreP and an AddP together (as part of an
1348 // address expression) and the AddP and StoreP have
1349 // different controls.
1350 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1351 }
1352 _igvn.remove_dead_node(n);
1353 }
1354 }
1355 }
1356 }
1357
1358 try_move_store_after_loop(n);
1359
1360 // Check for Opaque2's who's loop has disappeared - who's input is in the
1361 // same loop nest as their output. Remove 'em, they are no longer useful.
1362 if( n_op == Op_Opaque2 &&
1363 n->in(1) != NULL &&
1364 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1365 _igvn.replace_node( n, n->in(1) );
1366 }
1367 }
1368
1369 //------------------------------split_if_with_blocks---------------------------
1370 // Check for aggressive application of 'split-if' optimization,
1371 // using basic block level info.
1372 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1373 Node *n = C->root();
1374 visited.set(n->_idx); // first, mark node as visited
1375 // Do pre-visit work for root
1376 n = split_if_with_blocks_pre( n );
1377 uint cnt = n->outcnt();
1378 uint i = 0;
1379 while (true) {
1380 // Visit all children
1381 if (i < cnt) {
1382 Node* use = n->raw_out(i);
1383 ++i;
1384 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1385 // Now do pre-visit work for this use
1386 use = split_if_with_blocks_pre( use );
1387 nstack.push(n, i); // Save parent and next use's index.
1388 n = use; // Process all children of current use.
1389 cnt = use->outcnt();
1390 i = 0;
1391 }
1392 }
1393 else {
1394 // All of n's children have been processed, complete post-processing.
1395 if (cnt != 0 && !n->is_Con()) {
1396 assert(has_node(n), "no dead nodes");
1397 split_if_with_blocks_post( n );
1398 }
1399 if (nstack.is_empty()) {
1400 // Finished all nodes on stack.
1401 break;
1402 }
1403 // Get saved parent node and next use's index. Visit the rest of uses.
1404 n = nstack.node();
1405 cnt = n->outcnt();
1406 i = nstack.index();
1407 nstack.pop();
1408 }
1409 }
1410 }
1411
1412
1413 //=============================================================================
1414 //
1415 // C L O N E A L O O P B O D Y
1416 //
1417
1418 //------------------------------clone_iff--------------------------------------
1419 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1420 // "Nearly" because all Nodes have been cloned from the original in the loop,
1421 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1422 // through the Phi recursively, and return a Bool.
1423 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1424
1425 // Convert this Phi into a Phi merging Bools
1426 uint i;
1427 for( i = 1; i < phi->req(); i++ ) {
1428 Node *b = phi->in(i);
1429 if( b->is_Phi() ) {
1430 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1431 } else {
1432 assert( b->is_Bool(), "" );
1433 }
1434 }
1435
1436 Node *sample_bool = phi->in(1);
1437 Node *sample_cmp = sample_bool->in(1);
1438
1439 // Make Phis to merge the Cmp's inputs.
1440 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1441 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1442 for( i = 1; i < phi->req(); i++ ) {
1443 Node *n1 = phi->in(i)->in(1)->in(1);
1444 Node *n2 = phi->in(i)->in(1)->in(2);
1445 phi1->set_req( i, n1 );
1446 phi2->set_req( i, n2 );
1447 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1448 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1449 }
1450 // See if these Phis have been made before.
1451 // Register with optimizer
1452 Node *hit1 = _igvn.hash_find_insert(phi1);
1453 if( hit1 ) { // Hit, toss just made Phi
1454 _igvn.remove_dead_node(phi1); // Remove new phi
1455 assert( hit1->is_Phi(), "" );
1456 phi1 = (PhiNode*)hit1; // Use existing phi
1457 } else { // Miss
1458 _igvn.register_new_node_with_optimizer(phi1);
1459 }
1460 Node *hit2 = _igvn.hash_find_insert(phi2);
1461 if( hit2 ) { // Hit, toss just made Phi
1462 _igvn.remove_dead_node(phi2); // Remove new phi
1463 assert( hit2->is_Phi(), "" );
1464 phi2 = (PhiNode*)hit2; // Use existing phi
1465 } else { // Miss
1466 _igvn.register_new_node_with_optimizer(phi2);
1467 }
1468 // Register Phis with loop/block info
1469 set_ctrl(phi1, phi->in(0));
1470 set_ctrl(phi2, phi->in(0));
1471 // Make a new Cmp
1472 Node *cmp = sample_cmp->clone();
1473 cmp->set_req( 1, phi1 );
1474 cmp->set_req( 2, phi2 );
1475 _igvn.register_new_node_with_optimizer(cmp);
1476 set_ctrl(cmp, phi->in(0));
1477
1478 // Make a new Bool
1479 Node *b = sample_bool->clone();
1480 b->set_req(1,cmp);
1481 _igvn.register_new_node_with_optimizer(b);
1482 set_ctrl(b, phi->in(0));
1483
1484 assert( b->is_Bool(), "" );
1485 return (BoolNode*)b;
1486 }
1487
1488 //------------------------------clone_bool-------------------------------------
1489 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1490 // "Nearly" because all Nodes have been cloned from the original in the loop,
1491 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1492 // through the Phi recursively, and return a Bool.
1493 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1494 uint i;
1495 // Convert this Phi into a Phi merging Bools
1496 for( i = 1; i < phi->req(); i++ ) {
1497 Node *b = phi->in(i);
1498 if( b->is_Phi() ) {
1499 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1500 } else {
1501 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1502 }
1503 }
1504
1505 Node *sample_cmp = phi->in(1);
1506
1507 // Make Phis to merge the Cmp's inputs.
1508 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1509 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1510 for( uint j = 1; j < phi->req(); j++ ) {
1511 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1512 Node *n1, *n2;
1513 if( cmp_top->is_Cmp() ) {
1514 n1 = cmp_top->in(1);
1515 n2 = cmp_top->in(2);
1516 } else {
1517 n1 = n2 = cmp_top;
1518 }
1519 phi1->set_req( j, n1 );
1520 phi2->set_req( j, n2 );
1521 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1522 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1523 }
1524
1525 // See if these Phis have been made before.
1526 // Register with optimizer
1527 Node *hit1 = _igvn.hash_find_insert(phi1);
1528 if( hit1 ) { // Hit, toss just made Phi
1529 _igvn.remove_dead_node(phi1); // Remove new phi
1530 assert( hit1->is_Phi(), "" );
1531 phi1 = (PhiNode*)hit1; // Use existing phi
1532 } else { // Miss
1533 _igvn.register_new_node_with_optimizer(phi1);
1534 }
1535 Node *hit2 = _igvn.hash_find_insert(phi2);
1536 if( hit2 ) { // Hit, toss just made Phi
1537 _igvn.remove_dead_node(phi2); // Remove new phi
1538 assert( hit2->is_Phi(), "" );
1539 phi2 = (PhiNode*)hit2; // Use existing phi
1540 } else { // Miss
1541 _igvn.register_new_node_with_optimizer(phi2);
1542 }
1543 // Register Phis with loop/block info
1544 set_ctrl(phi1, phi->in(0));
1545 set_ctrl(phi2, phi->in(0));
1546 // Make a new Cmp
1547 Node *cmp = sample_cmp->clone();
1548 cmp->set_req( 1, phi1 );
1549 cmp->set_req( 2, phi2 );
1550 _igvn.register_new_node_with_optimizer(cmp);
1551 set_ctrl(cmp, phi->in(0));
1552
1553 assert( cmp->is_Cmp(), "" );
1554 return (CmpNode*)cmp;
1555 }
1556
1557 //------------------------------sink_use---------------------------------------
1558 // If 'use' was in the loop-exit block, it now needs to be sunk
1559 // below the post-loop merge point.
1560 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1561 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1562 set_ctrl(use, post_loop);
1563 for (DUIterator j = use->outs(); use->has_out(j); j++)
1564 sink_use(use->out(j), post_loop);
1565 }
1566 }
1567
1568 //------------------------------clone_loop-------------------------------------
1569 //
1570 // C L O N E A L O O P B O D Y
1571 //
1572 // This is the basic building block of the loop optimizations. It clones an
1573 // entire loop body. It makes an old_new loop body mapping; with this mapping
1574 // you can find the new-loop equivalent to an old-loop node. All new-loop
1575 // nodes are exactly equal to their old-loop counterparts, all edges are the
1576 // same. All exits from the old-loop now have a RegionNode that merges the
1577 // equivalent new-loop path. This is true even for the normal "loop-exit"
1578 // condition. All uses of loop-invariant old-loop values now come from (one
1579 // or more) Phis that merge their new-loop equivalents.
1580 //
1581 // This operation leaves the graph in an illegal state: there are two valid
1582 // control edges coming from the loop pre-header to both loop bodies. I'll
1583 // definitely have to hack the graph after running this transform.
1584 //
1585 // From this building block I will further edit edges to perform loop peeling
1586 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1587 //
1588 // Parameter side_by_size_idom:
1589 // When side_by_size_idom is NULL, the dominator tree is constructed for
1590 // the clone loop to dominate the original. Used in construction of
1591 // pre-main-post loop sequence.
1592 // When nonnull, the clone and original are side-by-side, both are
1593 // dominated by the side_by_side_idom node. Used in construction of
1594 // unswitched loops.
1595 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1596 Node* side_by_side_idom) {
1597
1598 if (C->do_vector_loop() && PrintOpto) {
1599 const char* mname = C->method()->name()->as_quoted_ascii();
1600 if (mname != NULL) {
1601 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1602 }
1603 }
1604
1605 CloneMap& cm = C->clone_map();
1606 Dict* dict = cm.dict();
1607 if (C->do_vector_loop()) {
1608 cm.set_clone_idx(cm.max_gen()+1);
1609 #ifndef PRODUCT
1610 if (PrintOpto) {
1611 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1612 loop->dump_head();
1613 }
1614 #endif
1615 }
1616
1617 // Step 1: Clone the loop body. Make the old->new mapping.
1618 uint i;
1619 for( i = 0; i < loop->_body.size(); i++ ) {
1620 Node *old = loop->_body.at(i);
1621 Node *nnn = old->clone();
1622 old_new.map( old->_idx, nnn );
1623 if (C->do_vector_loop()) {
1624 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1625 }
1626 _igvn.register_new_node_with_optimizer(nnn);
1627 }
1628
1629
1630 // Step 2: Fix the edges in the new body. If the old input is outside the
1631 // loop use it. If the old input is INside the loop, use the corresponding
1632 // new node instead.
1633 for( i = 0; i < loop->_body.size(); i++ ) {
1634 Node *old = loop->_body.at(i);
1635 Node *nnn = old_new[old->_idx];
1636 // Fix CFG/Loop controlling the new node
1637 if (has_ctrl(old)) {
1638 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1639 } else {
1640 set_loop(nnn, loop->_parent);
1641 if (old->outcnt() > 0) {
1642 set_idom( nnn, old_new[idom(old)->_idx], dd );
1643 }
1644 }
1645 // Correct edges to the new node
1646 for( uint j = 0; j < nnn->req(); j++ ) {
1647 Node *n = nnn->in(j);
1648 if( n ) {
1649 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1650 if( loop->is_member( old_in_loop ) )
1651 nnn->set_req(j, old_new[n->_idx]);
1652 }
1653 }
1654 _igvn.hash_find_insert(nnn);
1655 }
1656 Node *newhead = old_new[loop->_head->_idx];
1657 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1658
1659
1660 // Step 3: Now fix control uses. Loop varying control uses have already
1661 // been fixed up (as part of all input edges in Step 2). Loop invariant
1662 // control uses must be either an IfFalse or an IfTrue. Make a merge
1663 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1664 // refer to this.
1665 ResourceArea *area = Thread::current()->resource_area();
1666 Node_List worklist(area);
1667 uint new_counter = C->unique();
1668 for( i = 0; i < loop->_body.size(); i++ ) {
1669 Node* old = loop->_body.at(i);
1670 if( !old->is_CFG() ) continue;
1671 Node* nnn = old_new[old->_idx];
1672
1673 // Copy uses to a worklist, so I can munge the def-use info
1674 // with impunity.
1675 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1676 worklist.push(old->fast_out(j));
1677
1678 while( worklist.size() ) { // Visit all uses
1679 Node *use = worklist.pop();
1680 if (!has_node(use)) continue; // Ignore dead nodes
1681 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1682 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1683 // Both OLD and USE are CFG nodes here.
1684 assert( use->is_Proj(), "" );
1685
1686 // Clone the loop exit control projection
1687 Node *newuse = use->clone();
1688 if (C->do_vector_loop()) {
1689 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1690 }
1691 newuse->set_req(0,nnn);
1692 _igvn.register_new_node_with_optimizer(newuse);
1693 set_loop(newuse, use_loop);
1694 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1695
1696 // We need a Region to merge the exit from the peeled body and the
1697 // exit from the old loop body.
1698 RegionNode *r = new RegionNode(3);
1699 // Map the old use to the new merge point
1700 old_new.map( use->_idx, r );
1701 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1702 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1703
1704 // The original user of 'use' uses 'r' instead.
1705 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1706 Node* useuse = use->last_out(l);
1707 _igvn.rehash_node_delayed(useuse);
1708 uint uses_found = 0;
1709 if( useuse->in(0) == use ) {
1710 useuse->set_req(0, r);
1711 uses_found++;
1712 if( useuse->is_CFG() ) {
1713 assert( dom_depth(useuse) > dd_r, "" );
1714 set_idom(useuse, r, dom_depth(useuse));
1715 }
1716 }
1717 for( uint k = 1; k < useuse->req(); k++ ) {
1718 if( useuse->in(k) == use ) {
1719 useuse->set_req(k, r);
1720 uses_found++;
1721 }
1722 }
1723 l -= uses_found; // we deleted 1 or more copies of this edge
1724 }
1725
1726 // Now finish up 'r'
1727 r->set_req( 1, newuse );
1728 r->set_req( 2, use );
1729 _igvn.register_new_node_with_optimizer(r);
1730 set_loop(r, use_loop);
1731 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1732 } // End of if a loop-exit test
1733 }
1734 }
1735
1736 // Step 4: If loop-invariant use is not control, it must be dominated by a
1737 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1738 // there if needed. Make a Phi there merging old and new used values.
1739 Node_List *split_if_set = NULL;
1740 Node_List *split_bool_set = NULL;
1741 Node_List *split_cex_set = NULL;
1742 for( i = 0; i < loop->_body.size(); i++ ) {
1743 Node* old = loop->_body.at(i);
1744 Node* nnn = old_new[old->_idx];
1745 // Copy uses to a worklist, so I can munge the def-use info
1746 // with impunity.
1747 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1748 worklist.push(old->fast_out(j));
1749
1750 while( worklist.size() ) {
1751 Node *use = worklist.pop();
1752 if (!has_node(use)) continue; // Ignore dead nodes
1753 if (use->in(0) == C->top()) continue;
1754 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1755 // Check for data-use outside of loop - at least one of OLD or USE
1756 // must not be a CFG node.
1757 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1758
1759 // If the Data use is an IF, that means we have an IF outside of the
1760 // loop that is switching on a condition that is set inside of the
1761 // loop. Happens if people set a loop-exit flag; then test the flag
1762 // in the loop to break the loop, then test is again outside of the
1763 // loop to determine which way the loop exited.
1764 // Loop predicate If node connects to Bool node through Opaque1 node.
1765 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1766 // Since this code is highly unlikely, we lazily build the worklist
1767 // of such Nodes to go split.
1768 if( !split_if_set )
1769 split_if_set = new Node_List(area);
1770 split_if_set->push(use);
1771 }
1772 if( use->is_Bool() ) {
1773 if( !split_bool_set )
1774 split_bool_set = new Node_List(area);
1775 split_bool_set->push(use);
1776 }
1777 if( use->Opcode() == Op_CreateEx ) {
1778 if( !split_cex_set )
1779 split_cex_set = new Node_List(area);
1780 split_cex_set->push(use);
1781 }
1782
1783
1784 // Get "block" use is in
1785 uint idx = 0;
1786 while( use->in(idx) != old ) idx++;
1787 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1788 assert( !loop->is_member( get_loop( prev ) ), "" );
1789 Node *cfg = prev->_idx >= new_counter
1790 ? prev->in(2)
1791 : idom(prev);
1792 if( use->is_Phi() ) // Phi use is in prior block
1793 cfg = prev->in(idx); // NOT in block of Phi itself
1794 if (cfg->is_top()) { // Use is dead?
1795 _igvn.replace_input_of(use, idx, C->top());
1796 continue;
1797 }
1798
1799 while( !loop->is_member( get_loop( cfg ) ) ) {
1800 prev = cfg;
1801 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1802 }
1803 // If the use occurs after merging several exits from the loop, then
1804 // old value must have dominated all those exits. Since the same old
1805 // value was used on all those exits we did not need a Phi at this
1806 // merge point. NOW we do need a Phi here. Each loop exit value
1807 // is now merged with the peeled body exit; each exit gets its own
1808 // private Phi and those Phis need to be merged here.
1809 Node *phi;
1810 if( prev->is_Region() ) {
1811 if( idx == 0 ) { // Updating control edge?
1812 phi = prev; // Just use existing control
1813 } else { // Else need a new Phi
1814 phi = PhiNode::make( prev, old );
1815 // Now recursively fix up the new uses of old!
1816 for( uint i = 1; i < prev->req(); i++ ) {
1817 worklist.push(phi); // Onto worklist once for each 'old' input
1818 }
1819 }
1820 } else {
1821 // Get new RegionNode merging old and new loop exits
1822 prev = old_new[prev->_idx];
1823 assert( prev, "just made this in step 7" );
1824 if( idx == 0 ) { // Updating control edge?
1825 phi = prev; // Just use existing control
1826 } else { // Else need a new Phi
1827 // Make a new Phi merging data values properly
1828 phi = PhiNode::make( prev, old );
1829 phi->set_req( 1, nnn );
1830 }
1831 }
1832 // If inserting a new Phi, check for prior hits
1833 if( idx != 0 ) {
1834 Node *hit = _igvn.hash_find_insert(phi);
1835 if( hit == NULL ) {
1836 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1837 } else { // or
1838 // Remove the new phi from the graph and use the hit
1839 _igvn.remove_dead_node(phi);
1840 phi = hit; // Use existing phi
1841 }
1842 set_ctrl(phi, prev);
1843 }
1844 // Make 'use' use the Phi instead of the old loop body exit value
1845 _igvn.replace_input_of(use, idx, phi);
1846 if( use->_idx >= new_counter ) { // If updating new phis
1847 // Not needed for correctness, but prevents a weak assert
1848 // in AddPNode from tripping (when we end up with different
1849 // base & derived Phis that will become the same after
1850 // IGVN does CSE).
1851 Node *hit = _igvn.hash_find_insert(use);
1852 if( hit ) // Go ahead and re-hash for hits.
1853 _igvn.replace_node( use, hit );
1854 }
1855
1856 // If 'use' was in the loop-exit block, it now needs to be sunk
1857 // below the post-loop merge point.
1858 sink_use( use, prev );
1859 }
1860 }
1861 }
1862
1863 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1864 // the loop uses a condition set in the loop. The original IF probably
1865 // takes control from one or more OLD Regions (which in turn get from NEW
1866 // Regions). In any case, there will be a set of Phis for each merge point
1867 // from the IF up to where the original BOOL def exists the loop.
1868 if( split_if_set ) {
1869 while( split_if_set->size() ) {
1870 Node *iff = split_if_set->pop();
1871 if( iff->in(1)->is_Phi() ) {
1872 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1873 _igvn.replace_input_of(iff, 1, b);
1874 }
1875 }
1876 }
1877 if( split_bool_set ) {
1878 while( split_bool_set->size() ) {
1879 Node *b = split_bool_set->pop();
1880 Node *phi = b->in(1);
1881 assert( phi->is_Phi(), "" );
1882 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1883 _igvn.replace_input_of(b, 1, cmp);
1884 }
1885 }
1886 if( split_cex_set ) {
1887 while( split_cex_set->size() ) {
1888 Node *b = split_cex_set->pop();
1889 assert( b->in(0)->is_Region(), "" );
1890 assert( b->in(1)->is_Phi(), "" );
1891 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1892 split_up( b, b->in(0), NULL );
1893 }
1894 }
1895
1896 }
1897
1898
1899 //---------------------- stride_of_possible_iv -------------------------------------
1900 // Looks for an iff/bool/comp with one operand of the compare
1901 // being a cycle involving an add and a phi,
1902 // with an optional truncation (left-shift followed by a right-shift)
1903 // of the add. Returns zero if not an iv.
1904 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1905 Node* trunc1 = NULL;
1906 Node* trunc2 = NULL;
1907 const TypeInt* ttype = NULL;
1908 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1909 return 0;
1910 }
1911 BoolNode* bl = iff->in(1)->as_Bool();
1912 Node* cmp = bl->in(1);
1913 if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
1914 return 0;
1915 }
1916 // Must have an invariant operand
1917 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1918 return 0;
1919 }
1920 Node* add2 = NULL;
1921 Node* cmp1 = cmp->in(1);
1922 if (cmp1->is_Phi()) {
1923 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1924 Node* phi = cmp1;
1925 for (uint i = 1; i < phi->req(); i++) {
1926 Node* in = phi->in(i);
1927 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1928 &trunc1, &trunc2, &ttype);
1929 if (add && add->in(1) == phi) {
1930 add2 = add->in(2);
1931 break;
1932 }
1933 }
1934 } else {
1935 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1936 Node* addtrunc = cmp1;
1937 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1938 &trunc1, &trunc2, &ttype);
1939 if (add && add->in(1)->is_Phi()) {
1940 Node* phi = add->in(1);
1941 for (uint i = 1; i < phi->req(); i++) {
1942 if (phi->in(i) == addtrunc) {
1943 add2 = add->in(2);
1944 break;
1945 }
1946 }
1947 }
1948 }
1949 if (add2 != NULL) {
1950 const TypeInt* add2t = _igvn.type(add2)->is_int();
1951 if (add2t->is_con()) {
1952 return add2t->get_con();
1953 }
1954 }
1955 return 0;
1956 }
1957
1958
1959 //---------------------- stay_in_loop -------------------------------------
1960 // Return the (unique) control output node that's in the loop (if it exists.)
1961 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1962 Node* unique = NULL;
1963 if (!n) return NULL;
1964 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1965 Node* use = n->fast_out(i);
1966 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1967 if (unique != NULL) {
1968 return NULL;
1969 }
1970 unique = use;
1971 }
1972 }
1973 return unique;
1974 }
1975
1976 //------------------------------ register_node -------------------------------------
1977 // Utility to register node "n" with PhaseIdealLoop
1978 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1979 _igvn.register_new_node_with_optimizer(n);
1980 loop->_body.push(n);
1981 if (n->is_CFG()) {
1982 set_loop(n, loop);
1983 set_idom(n, pred, ddepth);
1984 } else {
1985 set_ctrl(n, pred);
1986 }
1987 }
1988
1989 //------------------------------ proj_clone -------------------------------------
1990 // Utility to create an if-projection
1991 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1992 ProjNode* c = p->clone()->as_Proj();
1993 c->set_req(0, iff);
1994 return c;
1995 }
1996
1997 //------------------------------ short_circuit_if -------------------------------------
1998 // Force the iff control output to be the live_proj
1999 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2000 guarantee(live_proj != NULL, "null projection");
2001 int proj_con = live_proj->_con;
2002 assert(proj_con == 0 || proj_con == 1, "false or true projection");
2003 Node *con = _igvn.intcon(proj_con);
2004 set_ctrl(con, C->root());
2005 if (iff) {
2006 iff->set_req(1, con);
2007 }
2008 return con;
2009 }
2010
2011 //------------------------------ insert_if_before_proj -------------------------------------
2012 // Insert a new if before an if projection (* - new node)
2013 //
2014 // before
2015 // if(test)
2016 // / \
2017 // v v
2018 // other-proj proj (arg)
2019 //
2020 // after
2021 // if(test)
2022 // / \
2023 // / v
2024 // | * proj-clone
2025 // v |
2026 // other-proj v
2027 // * new_if(relop(cmp[IU](left,right)))
2028 // / \
2029 // v v
2030 // * new-proj proj
2031 // (returned)
2032 //
2033 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2034 IfNode* iff = proj->in(0)->as_If();
2035 IdealLoopTree *loop = get_loop(proj);
2036 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2037 int ddepth = dom_depth(proj);
2038
2039 _igvn.rehash_node_delayed(iff);
2040 _igvn.rehash_node_delayed(proj);
2041
2042 proj->set_req(0, NULL); // temporary disconnect
2043 ProjNode* proj2 = proj_clone(proj, iff);
2044 register_node(proj2, loop, iff, ddepth);
2045
2046 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2047 register_node(cmp, loop, proj2, ddepth);
2048
2049 BoolNode* bol = new BoolNode(cmp, relop);
2050 register_node(bol, loop, proj2, ddepth);
2051
2052 int opcode = iff->Opcode();
2053 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2054 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2055 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2056 register_node(new_if, loop, proj2, ddepth);
2057
2058 proj->set_req(0, new_if); // reattach
2059 set_idom(proj, new_if, ddepth);
2060
2061 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2062 guarantee(new_exit != NULL, "null exit node");
2063 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2064
2065 return new_exit;
2066 }
2067
2068 //------------------------------ insert_region_before_proj -------------------------------------
2069 // Insert a region before an if projection (* - new node)
2070 //
2071 // before
2072 // if(test)
2073 // / |
2074 // v |
2075 // proj v
2076 // other-proj
2077 //
2078 // after
2079 // if(test)
2080 // / |
2081 // v |
2082 // * proj-clone v
2083 // | other-proj
2084 // v
2085 // * new-region
2086 // |
2087 // v
2088 // * dum_if
2089 // / \
2090 // v \
2091 // * dum-proj v
2092 // proj
2093 //
2094 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2095 IfNode* iff = proj->in(0)->as_If();
2096 IdealLoopTree *loop = get_loop(proj);
2097 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2098 int ddepth = dom_depth(proj);
2099
2100 _igvn.rehash_node_delayed(iff);
2101 _igvn.rehash_node_delayed(proj);
2102
2103 proj->set_req(0, NULL); // temporary disconnect
2104 ProjNode* proj2 = proj_clone(proj, iff);
2105 register_node(proj2, loop, iff, ddepth);
2106
2107 RegionNode* reg = new RegionNode(2);
2108 reg->set_req(1, proj2);
2109 register_node(reg, loop, iff, ddepth);
2110
2111 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2112 register_node(dum_if, loop, reg, ddepth);
2113
2114 proj->set_req(0, dum_if); // reattach
2115 set_idom(proj, dum_if, ddepth);
2116
2117 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2118 register_node(dum_proj, loop, dum_if, ddepth);
2119
2120 return reg;
2121 }
2122
2123 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2124 // Clone a signed compare loop exit from an unsigned compare and
2125 // insert it before the unsigned cmp on the stay-in-loop path.
2126 // All new nodes inserted in the dominator tree between the original
2127 // if and it's projections. The original if test is replaced with
2128 // a constant to force the stay-in-loop path.
2129 //
2130 // This is done to make sure that the original if and it's projections
2131 // still dominate the same set of control nodes, that the ctrl() relation
2132 // from data nodes to them is preserved, and that their loop nesting is
2133 // preserved.
2134 //
2135 // before
2136 // if(i <u limit) unsigned compare loop exit
2137 // / |
2138 // v v
2139 // exit-proj stay-in-loop-proj
2140 //
2141 // after
2142 // if(stay-in-loop-const) original if
2143 // / |
2144 // / v
2145 // / if(i < limit) new signed test
2146 // / / |
2147 // / / v
2148 // / / if(i <u limit) new cloned unsigned test
2149 // / / / |
2150 // v v v |
2151 // region |
2152 // | |
2153 // dum-if |
2154 // / | |
2155 // ether | |
2156 // v v
2157 // exit-proj stay-in-loop-proj
2158 //
2159 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2160 const bool Signed = true;
2161 const bool Unsigned = false;
2162
2163 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2164 if (bol->_test._test != BoolTest::lt) return NULL;
2165 CmpNode* cmpu = bol->in(1)->as_Cmp();
2166 if (cmpu->Opcode() != Op_CmpU) return NULL;
2167 int stride = stride_of_possible_iv(if_cmpu);
2168 if (stride == 0) return NULL;
2169
2170 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2171 guarantee(lp_proj != NULL, "null loop node");
2172
2173 ProjNode* lp_continue = lp_proj->as_Proj();
2174 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2175
2176 Node* limit = NULL;
2177 if (stride > 0) {
2178 limit = cmpu->in(2);
2179 } else {
2180 limit = _igvn.makecon(TypeInt::ZERO);
2181 set_ctrl(limit, C->root());
2182 }
2183 // Create a new region on the exit path
2184 RegionNode* reg = insert_region_before_proj(lp_exit);
2185 guarantee(reg != NULL, "null region node");
2186
2187 // Clone the if-cmpu-true-false using a signed compare
2188 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2189 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2190 reg->add_req(cmpi_exit);
2191
2192 // Clone the if-cmpu-true-false
2193 BoolTest::mask rel_u = bol->_test._test;
2194 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2195 reg->add_req(cmpu_exit);
2196
2197 // Force original if to stay in loop.
2198 short_circuit_if(if_cmpu, lp_continue);
2199
2200 return cmpi_exit->in(0)->as_If();
2201 }
2202
2203 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2204 // Remove a previously inserted signed compare loop exit.
2205 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2206 Node* lp_proj = stay_in_loop(if_cmp, loop);
2207 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2208 stay_in_loop(lp_proj, loop)->is_If() &&
2209 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2210 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2211 set_ctrl(con, C->root());
2212 if_cmp->set_req(1, con);
2213 }
2214
2215 //------------------------------ scheduled_nodelist -------------------------------------
2216 // Create a post order schedule of nodes that are in the
2217 // "member" set. The list is returned in "sched".
2218 // The first node in "sched" is the loop head, followed by
2219 // nodes which have no inputs in the "member" set, and then
2220 // followed by the nodes that have an immediate input dependence
2221 // on a node in "sched".
2222 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2223
2224 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2225 Arena *a = Thread::current()->resource_area();
2226 VectorSet visited(a);
2227 Node_Stack nstack(a, loop->_body.size());
2228
2229 Node* n = loop->_head; // top of stack is cached in "n"
2230 uint idx = 0;
2231 visited.set(n->_idx);
2232
2233 // Initially push all with no inputs from within member set
2234 for(uint i = 0; i < loop->_body.size(); i++ ) {
2235 Node *elt = loop->_body.at(i);
2236 if (member.test(elt->_idx)) {
2237 bool found = false;
2238 for (uint j = 0; j < elt->req(); j++) {
2239 Node* def = elt->in(j);
2240 if (def && member.test(def->_idx) && def != elt) {
2241 found = true;
2242 break;
2243 }
2244 }
2245 if (!found && elt != loop->_head) {
2246 nstack.push(n, idx);
2247 n = elt;
2248 assert(!visited.test(n->_idx), "not seen yet");
2249 visited.set(n->_idx);
2250 }
2251 }
2252 }
2253
2254 // traverse out's that are in the member set
2255 while (true) {
2256 if (idx < n->outcnt()) {
2257 Node* use = n->raw_out(idx);
2258 idx++;
2259 if (!visited.test_set(use->_idx)) {
2260 if (member.test(use->_idx)) {
2261 nstack.push(n, idx);
2262 n = use;
2263 idx = 0;
2264 }
2265 }
2266 } else {
2267 // All outputs processed
2268 sched.push(n);
2269 if (nstack.is_empty()) break;
2270 n = nstack.node();
2271 idx = nstack.index();
2272 nstack.pop();
2273 }
2274 }
2275 }
2276
2277
2278 //------------------------------ has_use_in_set -------------------------------------
2279 // Has a use in the vector set
2280 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2281 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2282 Node* use = n->fast_out(j);
2283 if (vset.test(use->_idx)) {
2284 return true;
2285 }
2286 }
2287 return false;
2288 }
2289
2290
2291 //------------------------------ has_use_internal_to_set -------------------------------------
2292 // Has use internal to the vector set (ie. not in a phi at the loop head)
2293 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2294 Node* head = loop->_head;
2295 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2296 Node* use = n->fast_out(j);
2297 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2298 return true;
2299 }
2300 }
2301 return false;
2302 }
2303
2304
2305 //------------------------------ clone_for_use_outside_loop -------------------------------------
2306 // clone "n" for uses that are outside of loop
2307 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2308 int cloned = 0;
2309 assert(worklist.size() == 0, "should be empty");
2310 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2311 Node* use = n->fast_out(j);
2312 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2313 worklist.push(use);
2314 }
2315 }
2316 while( worklist.size() ) {
2317 Node *use = worklist.pop();
2318 if (!has_node(use) || use->in(0) == C->top()) continue;
2319 uint j;
2320 for (j = 0; j < use->req(); j++) {
2321 if (use->in(j) == n) break;
2322 }
2323 assert(j < use->req(), "must be there");
2324
2325 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2326 Node* n_clone = n->clone();
2327 _igvn.replace_input_of(use, j, n_clone);
2328 cloned++;
2329 Node* use_c;
2330 if (!use->is_Phi()) {
2331 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2332 } else {
2333 // Use in a phi is considered a use in the associated predecessor block
2334 use_c = use->in(0)->in(j);
2335 }
2336 set_ctrl(n_clone, use_c);
2337 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2338 get_loop(use_c)->_body.push(n_clone);
2339 _igvn.register_new_node_with_optimizer(n_clone);
2340 #if !defined(PRODUCT)
2341 if (TracePartialPeeling) {
2342 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2343 }
2344 #endif
2345 }
2346 return cloned;
2347 }
2348
2349
2350 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2351 // clone "n" for special uses that are in the not_peeled region.
2352 // If these def-uses occur in separate blocks, the code generator
2353 // marks the method as not compilable. For example, if a "BoolNode"
2354 // is in a different basic block than the "IfNode" that uses it, then
2355 // the compilation is aborted in the code generator.
2356 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2357 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2358 if (n->is_Phi() || n->is_Load()) {
2359 return;
2360 }
2361 assert(worklist.size() == 0, "should be empty");
2362 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2363 Node* use = n->fast_out(j);
2364 if ( not_peel.test(use->_idx) &&
2365 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2366 use->in(1) == n) {
2367 worklist.push(use);
2368 }
2369 }
2370 if (worklist.size() > 0) {
2371 // clone "n" and insert it between inputs of "n" and the use
2372 Node* n_clone = n->clone();
2373 loop->_body.push(n_clone);
2374 _igvn.register_new_node_with_optimizer(n_clone);
2375 set_ctrl(n_clone, get_ctrl(n));
2376 sink_list.push(n_clone);
2377 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2378 #if !defined(PRODUCT)
2379 if (TracePartialPeeling) {
2380 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2381 }
2382 #endif
2383 while( worklist.size() ) {
2384 Node *use = worklist.pop();
2385 _igvn.rehash_node_delayed(use);
2386 for (uint j = 1; j < use->req(); j++) {
2387 if (use->in(j) == n) {
2388 use->set_req(j, n_clone);
2389 }
2390 }
2391 }
2392 }
2393 }
2394
2395
2396 //------------------------------ insert_phi_for_loop -------------------------------------
2397 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2398 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2399 Node *phi = PhiNode::make(lp, back_edge_val);
2400 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2401 // Use existing phi if it already exists
2402 Node *hit = _igvn.hash_find_insert(phi);
2403 if( hit == NULL ) {
2404 _igvn.register_new_node_with_optimizer(phi);
2405 set_ctrl(phi, lp);
2406 } else {
2407 // Remove the new phi from the graph and use the hit
2408 _igvn.remove_dead_node(phi);
2409 phi = hit;
2410 }
2411 _igvn.replace_input_of(use, idx, phi);
2412 }
2413
2414 #ifdef ASSERT
2415 //------------------------------ is_valid_loop_partition -------------------------------------
2416 // Validate the loop partition sets: peel and not_peel
2417 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2418 VectorSet& not_peel ) {
2419 uint i;
2420 // Check that peel_list entries are in the peel set
2421 for (i = 0; i < peel_list.size(); i++) {
2422 if (!peel.test(peel_list.at(i)->_idx)) {
2423 return false;
2424 }
2425 }
2426 // Check at loop members are in one of peel set or not_peel set
2427 for (i = 0; i < loop->_body.size(); i++ ) {
2428 Node *def = loop->_body.at(i);
2429 uint di = def->_idx;
2430 // Check that peel set elements are in peel_list
2431 if (peel.test(di)) {
2432 if (not_peel.test(di)) {
2433 return false;
2434 }
2435 // Must be in peel_list also
2436 bool found = false;
2437 for (uint j = 0; j < peel_list.size(); j++) {
2438 if (peel_list.at(j)->_idx == di) {
2439 found = true;
2440 break;
2441 }
2442 }
2443 if (!found) {
2444 return false;
2445 }
2446 } else if (not_peel.test(di)) {
2447 if (peel.test(di)) {
2448 return false;
2449 }
2450 } else {
2451 return false;
2452 }
2453 }
2454 return true;
2455 }
2456
2457 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2458 // Ensure a use outside of loop is of the right form
2459 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2460 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2461 return (use->is_Phi() &&
2462 use_c->is_Region() && use_c->req() == 3 &&
2463 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2464 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2465 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2466 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2467 }
2468
2469 //------------------------------ is_valid_clone_loop_form -------------------------------------
2470 // Ensure that all uses outside of loop are of the right form
2471 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2472 uint orig_exit_idx, uint clone_exit_idx) {
2473 uint len = peel_list.size();
2474 for (uint i = 0; i < len; i++) {
2475 Node *def = peel_list.at(i);
2476
2477 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2478 Node *use = def->fast_out(j);
2479 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2480 if (!loop->is_member(get_loop(use_c))) {
2481 // use is not in the loop, check for correct structure
2482 if (use->in(0) == def) {
2483 // Okay
2484 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2485 return false;
2486 }
2487 }
2488 }
2489 }
2490 return true;
2491 }
2492 #endif
2493
2494 //------------------------------ partial_peel -------------------------------------
2495 // Partially peel (aka loop rotation) the top portion of a loop (called
2496 // the peel section below) by cloning it and placing one copy just before
2497 // the new loop head and the other copy at the bottom of the new loop.
2498 //
2499 // before after where it came from
2500 //
2501 // stmt1 stmt1
2502 // loop: stmt2 clone
2503 // stmt2 if condA goto exitA clone
2504 // if condA goto exitA new_loop: new
2505 // stmt3 stmt3 clone
2506 // if !condB goto loop if condB goto exitB clone
2507 // exitB: stmt2 orig
2508 // stmt4 if !condA goto new_loop orig
2509 // exitA: goto exitA
2510 // exitB:
2511 // stmt4
2512 // exitA:
2513 //
2514 // Step 1: find the cut point: an exit test on probable
2515 // induction variable.
2516 // Step 2: schedule (with cloning) operations in the peel
2517 // section that can be executed after the cut into
2518 // the section that is not peeled. This may need
2519 // to clone operations into exit blocks. For
2520 // instance, a reference to A[i] in the not-peel
2521 // section and a reference to B[i] in an exit block
2522 // may cause a left-shift of i by 2 to be placed
2523 // in the peel block. This step will clone the left
2524 // shift into the exit block and sink the left shift
2525 // from the peel to the not-peel section.
2526 // Step 3: clone the loop, retarget the control, and insert
2527 // phis for values that are live across the new loop
2528 // head. This is very dependent on the graph structure
2529 // from clone_loop. It creates region nodes for
2530 // exit control and associated phi nodes for values
2531 // flow out of the loop through that exit. The region
2532 // node is dominated by the clone's control projection.
2533 // So the clone's peel section is placed before the
2534 // new loop head, and the clone's not-peel section is
2535 // forms the top part of the new loop. The original
2536 // peel section forms the tail of the new loop.
2537 // Step 4: update the dominator tree and recompute the
2538 // dominator depth.
2539 //
2540 // orig
2541 //
2542 // stmt1
2543 // |
2544 // v
2545 // loop predicate
2546 // |
2547 // v
2548 // loop<----+
2549 // | |
2550 // stmt2 |
2551 // | |
2552 // v |
2553 // ifA |
2554 // / | |
2555 // v v |
2556 // false true ^ <-- last_peel
2557 // / | |
2558 // / ===|==cut |
2559 // / stmt3 | <-- first_not_peel
2560 // / | |
2561 // | v |
2562 // v ifB |
2563 // exitA: / \ |
2564 // / \ |
2565 // v v |
2566 // false true |
2567 // / \ |
2568 // / ----+
2569 // |
2570 // v
2571 // exitB:
2572 // stmt4
2573 //
2574 //
2575 // after clone loop
2576 //
2577 // stmt1
2578 // |
2579 // v
2580 // loop predicate
2581 // / \
2582 // clone / \ orig
2583 // / \
2584 // / \
2585 // v v
2586 // +---->loop loop<----+
2587 // | | | |
2588 // | stmt2 stmt2 |
2589 // | | | |
2590 // | v v |
2591 // | ifA ifA |
2592 // | | \ / | |
2593 // | v v v v |
2594 // ^ true false false true ^ <-- last_peel
2595 // | | ^ \ / | |
2596 // | cut==|== \ \ / ===|==cut |
2597 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2598 // | | dom | | | |
2599 // | v \ 1v v2 v |
2600 // | ifB regionA ifB |
2601 // | / \ | / \ |
2602 // | / \ v / \ |
2603 // | v v exitA: v v |
2604 // | true false false true |
2605 // | / ^ \ / \ |
2606 // +---- \ \ / ----+
2607 // dom \ /
2608 // \ 1v v2
2609 // regionB
2610 // |
2611 // v
2612 // exitB:
2613 // stmt4
2614 //
2615 //
2616 // after partial peel
2617 //
2618 // stmt1
2619 // |
2620 // v
2621 // loop predicate
2622 // /
2623 // clone / orig
2624 // / TOP
2625 // / \
2626 // v v
2627 // TOP->loop loop----+
2628 // | | |
2629 // stmt2 stmt2 |
2630 // | | |
2631 // v v |
2632 // ifA ifA |
2633 // | \ / | |
2634 // v v v v |
2635 // true false false true | <-- last_peel
2636 // | ^ \ / +------|---+
2637 // +->newloop \ \ / === ==cut | |
2638 // | stmt3 \ \ / TOP | |
2639 // | | dom | | stmt3 | | <-- first_not_peel
2640 // | v \ 1v v2 v | |
2641 // | ifB regionA ifB ^ v
2642 // | / \ | / \ | |
2643 // | / \ v / \ | |
2644 // | v v exitA: v v | |
2645 // | true false false true | |
2646 // | / ^ \ / \ | |
2647 // | | \ \ / v | |
2648 // | | dom \ / TOP | |
2649 // | | \ 1v v2 | |
2650 // ^ v regionB | |
2651 // | | | | |
2652 // | | v ^ v
2653 // | | exitB: | |
2654 // | | stmt4 | |
2655 // | +------------>-----------------+ |
2656 // | |
2657 // +-----------------<---------------------+
2658 //
2659 //
2660 // final graph
2661 //
2662 // stmt1
2663 // |
2664 // v
2665 // loop predicate
2666 // |
2667 // v
2668 // stmt2 clone
2669 // |
2670 // v
2671 // ........> ifA clone
2672 // : / |
2673 // dom / |
2674 // : v v
2675 // : false true
2676 // : | |
2677 // : | v
2678 // : | newloop<-----+
2679 // : | | |
2680 // : | stmt3 clone |
2681 // : | | |
2682 // : | v |
2683 // : | ifB |
2684 // : | / \ |
2685 // : | v v |
2686 // : | false true |
2687 // : | | | |
2688 // : | v stmt2 |
2689 // : | exitB: | |
2690 // : | stmt4 v |
2691 // : | ifA orig |
2692 // : | / \ |
2693 // : | / \ |
2694 // : | v v |
2695 // : | false true |
2696 // : | / \ |
2697 // : v v -----+
2698 // RegionA
2699 // |
2700 // v
2701 // exitA
2702 //
2703 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2704
2705 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2706 if (!loop->_head->is_Loop()) {
2707 return false; }
2708
2709 LoopNode *head = loop->_head->as_Loop();
2710
2711 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2712 return false;
2713 }
2714
2715 // Check for complex exit control
2716 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2717 Node *n = loop->_body.at(ii);
2718 int opc = n->Opcode();
2719 if (n->is_Call() ||
2720 opc == Op_Catch ||
2721 opc == Op_CatchProj ||
2722 opc == Op_Jump ||
2723 opc == Op_JumpProj) {
2724 #if !defined(PRODUCT)
2725 if (TracePartialPeeling) {
2726 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2727 }
2728 #endif
2729 return false;
2730 }
2731 }
2732
2733 int dd = dom_depth(head);
2734
2735 // Step 1: find cut point
2736
2737 // Walk up dominators to loop head looking for first loop exit
2738 // which is executed on every path thru loop.
2739 IfNode *peel_if = NULL;
2740 IfNode *peel_if_cmpu = NULL;
2741
2742 Node *iff = loop->tail();
2743 while( iff != head ) {
2744 if( iff->is_If() ) {
2745 Node *ctrl = get_ctrl(iff->in(1));
2746 if (ctrl->is_top()) return false; // Dead test on live IF.
2747 // If loop-varying exit-test, check for induction variable
2748 if( loop->is_member(get_loop(ctrl)) &&
2749 loop->is_loop_exit(iff) &&
2750 is_possible_iv_test(iff)) {
2751 Node* cmp = iff->in(1)->in(1);
2752 if (cmp->Opcode() == Op_CmpI) {
2753 peel_if = iff->as_If();
2754 } else {
2755 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2756 peel_if_cmpu = iff->as_If();
2757 }
2758 }
2759 }
2760 iff = idom(iff);
2761 }
2762 // Prefer signed compare over unsigned compare.
2763 IfNode* new_peel_if = NULL;
2764 if (peel_if == NULL) {
2765 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2766 return false; // No peel point found
2767 }
2768 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2769 if (new_peel_if == NULL) {
2770 return false; // No peel point found
2771 }
2772 peel_if = new_peel_if;
2773 }
2774 Node* last_peel = stay_in_loop(peel_if, loop);
2775 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2776 if (first_not_peeled == NULL || first_not_peeled == head) {
2777 return false;
2778 }
2779
2780 #if !defined(PRODUCT)
2781 if (TraceLoopOpts) {
2782 tty->print("PartialPeel ");
2783 loop->dump_head();
2784 }
2785
2786 if (TracePartialPeeling) {
2787 tty->print_cr("before partial peel one iteration");
2788 Node_List wl;
2789 Node* t = head->in(2);
2790 while (true) {
2791 wl.push(t);
2792 if (t == head) break;
2793 t = idom(t);
2794 }
2795 while (wl.size() > 0) {
2796 Node* tt = wl.pop();
2797 tt->dump();
2798 if (tt == last_peel) tty->print_cr("-- cut --");
2799 }
2800 }
2801 #endif
2802 ResourceArea *area = Thread::current()->resource_area();
2803 VectorSet peel(area);
2804 VectorSet not_peel(area);
2805 Node_List peel_list(area);
2806 Node_List worklist(area);
2807 Node_List sink_list(area);
2808
2809 // Set of cfg nodes to peel are those that are executable from
2810 // the head through last_peel.
2811 assert(worklist.size() == 0, "should be empty");
2812 worklist.push(head);
2813 peel.set(head->_idx);
2814 while (worklist.size() > 0) {
2815 Node *n = worklist.pop();
2816 if (n != last_peel) {
2817 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2818 Node* use = n->fast_out(j);
2819 if (use->is_CFG() &&
2820 loop->is_member(get_loop(use)) &&
2821 !peel.test_set(use->_idx)) {
2822 worklist.push(use);
2823 }
2824 }
2825 }
2826 }
2827
2828 // Set of non-cfg nodes to peel are those that are control
2829 // dependent on the cfg nodes.
2830 uint i;
2831 for(i = 0; i < loop->_body.size(); i++ ) {
2832 Node *n = loop->_body.at(i);
2833 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2834 if (peel.test(n_c->_idx)) {
2835 peel.set(n->_idx);
2836 } else {
2837 not_peel.set(n->_idx);
2838 }
2839 }
2840
2841 // Step 2: move operations from the peeled section down into the
2842 // not-peeled section
2843
2844 // Get a post order schedule of nodes in the peel region
2845 // Result in right-most operand.
2846 scheduled_nodelist(loop, peel, peel_list );
2847
2848 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2849
2850 // For future check for too many new phis
2851 uint old_phi_cnt = 0;
2852 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2853 Node* use = head->fast_out(j);
2854 if (use->is_Phi()) old_phi_cnt++;
2855 }
2856
2857 #if !defined(PRODUCT)
2858 if (TracePartialPeeling) {
2859 tty->print_cr("\npeeled list");
2860 }
2861 #endif
2862
2863 // Evacuate nodes in peel region into the not_peeled region if possible
2864 uint new_phi_cnt = 0;
2865 uint cloned_for_outside_use = 0;
2866 for (i = 0; i < peel_list.size();) {
2867 Node* n = peel_list.at(i);
2868 #if !defined(PRODUCT)
2869 if (TracePartialPeeling) n->dump();
2870 #endif
2871 bool incr = true;
2872 if ( !n->is_CFG() ) {
2873
2874 if ( has_use_in_set(n, not_peel) ) {
2875
2876 // If not used internal to the peeled region,
2877 // move "n" from peeled to not_peeled region.
2878
2879 if ( !has_use_internal_to_set(n, peel, loop) ) {
2880
2881 // if not pinned and not a load (which maybe anti-dependent on a store)
2882 // and not a CMove (Matcher expects only bool->cmove).
2883 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2884 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2885 sink_list.push(n);
2886 peel >>= n->_idx; // delete n from peel set.
2887 not_peel <<= n->_idx; // add n to not_peel set.
2888 peel_list.remove(i);
2889 incr = false;
2890 #if !defined(PRODUCT)
2891 if (TracePartialPeeling) {
2892 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2893 n->_idx, get_ctrl(n)->_idx);
2894 }
2895 #endif
2896 }
2897 } else {
2898 // Otherwise check for special def-use cases that span
2899 // the peel/not_peel boundary such as bool->if
2900 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2901 new_phi_cnt++;
2902 }
2903 }
2904 }
2905 if (incr) i++;
2906 }
2907
2908 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2909 #if !defined(PRODUCT)
2910 if (TracePartialPeeling) {
2911 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2912 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2913 }
2914 #endif
2915 if (new_peel_if != NULL) {
2916 remove_cmpi_loop_exit(new_peel_if, loop);
2917 }
2918 // Inhibit more partial peeling on this loop
2919 assert(!head->is_partial_peel_loop(), "not partial peeled");
2920 head->mark_partial_peel_failed();
2921 if (cloned_for_outside_use > 0) {
2922 // Terminate this round of loop opts because
2923 // the graph outside this loop was changed.
2924 C->set_major_progress();
2925 return true;
2926 }
2927 return false;
2928 }
2929
2930 // Step 3: clone loop, retarget control, and insert new phis
2931
2932 // Create new loop head for new phis and to hang
2933 // the nodes being moved (sinked) from the peel region.
2934 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2935 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2936 _igvn.register_new_node_with_optimizer(new_head);
2937 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2938 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2939 set_loop(new_head, loop);
2940 loop->_body.push(new_head);
2941 not_peel.set(new_head->_idx);
2942 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2943 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2944
2945 while (sink_list.size() > 0) {
2946 Node* n = sink_list.pop();
2947 set_ctrl(n, new_head);
2948 }
2949
2950 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2951
2952 clone_loop( loop, old_new, dd );
2953
2954 const uint clone_exit_idx = 1;
2955 const uint orig_exit_idx = 2;
2956 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2957
2958 Node* head_clone = old_new[head->_idx];
2959 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2960 Node* orig_tail_clone = head_clone->in(2);
2961
2962 // Add phi if "def" node is in peel set and "use" is not
2963
2964 for(i = 0; i < peel_list.size(); i++ ) {
2965 Node *def = peel_list.at(i);
2966 if (!def->is_CFG()) {
2967 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2968 Node *use = def->fast_out(j);
2969 if (has_node(use) && use->in(0) != C->top() &&
2970 (!peel.test(use->_idx) ||
2971 (use->is_Phi() && use->in(0) == head)) ) {
2972 worklist.push(use);
2973 }
2974 }
2975 while( worklist.size() ) {
2976 Node *use = worklist.pop();
2977 for (uint j = 1; j < use->req(); j++) {
2978 Node* n = use->in(j);
2979 if (n == def) {
2980
2981 // "def" is in peel set, "use" is not in peel set
2982 // or "use" is in the entry boundary (a phi) of the peel set
2983
2984 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2985
2986 if ( loop->is_member(get_loop( use_c )) ) {
2987 // use is in loop
2988 if (old_new[use->_idx] != NULL) { // null for dead code
2989 Node* use_clone = old_new[use->_idx];
2990 _igvn.replace_input_of(use, j, C->top());
2991 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2992 }
2993 } else {
2994 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2995 // use is not in the loop, check if the live range includes the cut
2996 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2997 if (not_peel.test(lp_if->_idx)) {
2998 assert(j == orig_exit_idx, "use from original loop");
2999 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3000 }
3001 }
3002 }
3003 }
3004 }
3005 }
3006 }
3007
3008 // Step 3b: retarget control
3009
3010 // Redirect control to the new loop head if a cloned node in
3011 // the not_peeled region has control that points into the peeled region.
3012 // This necessary because the cloned peeled region will be outside
3013 // the loop.
3014 // from to
3015 // cloned-peeled <---+
3016 // new_head_clone: | <--+
3017 // cloned-not_peeled in(0) in(0)
3018 // orig-peeled
3019
3020 for(i = 0; i < loop->_body.size(); i++ ) {
3021 Node *n = loop->_body.at(i);
3022 if (!n->is_CFG() && n->in(0) != NULL &&
3023 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3024 Node* n_clone = old_new[n->_idx];
3025 _igvn.replace_input_of(n_clone, 0, new_head_clone);
3026 }
3027 }
3028
3029 // Backedge of the surviving new_head (the clone) is original last_peel
3030 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3031
3032 // Cut first node in original not_peel set
3033 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
3034 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
3035 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
3036
3037 // Copy head_clone back-branch info to original head
3038 // and remove original head's loop entry and
3039 // clone head's back-branch
3040 _igvn.rehash_node_delayed(head); // Multiple edge updates
3041 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
3042 head->set_req(LoopNode::LoopBackControl, C->top());
3043 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3044
3045 // Similarly modify the phis
3046 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3047 Node* use = head->fast_out(k);
3048 if (use->is_Phi() && use->outcnt() > 0) {
3049 Node* use_clone = old_new[use->_idx];
3050 _igvn.rehash_node_delayed(use); // Multiple edge updates
3051 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
3052 use->set_req(LoopNode::LoopBackControl, C->top());
3053 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3054 }
3055 }
3056
3057 // Step 4: update dominator tree and dominator depth
3058
3059 set_idom(head, orig_tail_clone, dd);
3060 recompute_dom_depth();
3061
3062 // Inhibit more partial peeling on this loop
3063 new_head_clone->set_partial_peel_loop();
3064 C->set_major_progress();
3065 loop->record_for_igvn();
3066
3067 #if !defined(PRODUCT)
3068 if (TracePartialPeeling) {
3069 tty->print_cr("\nafter partial peel one iteration");
3070 Node_List wl(area);
3071 Node* t = last_peel;
3072 while (true) {
3073 wl.push(t);
3074 if (t == head_clone) break;
3075 t = idom(t);
3076 }
3077 while (wl.size() > 0) {
3078 Node* tt = wl.pop();
3079 if (tt == head) tty->print_cr("orig head");
3080 else if (tt == new_head_clone) tty->print_cr("new head");
3081 else if (tt == head_clone) tty->print_cr("clone head");
3082 tt->dump();
3083 }
3084 }
3085 #endif
3086 return true;
3087 }
3088
3089 //------------------------------reorg_offsets----------------------------------
3090 // Reorganize offset computations to lower register pressure. Mostly
3091 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3092 // then alive with the post-incremented trip counter forcing an extra
3093 // register move)
3094 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3095 // Perform it only for canonical counted loops.
3096 // Loop's shape could be messed up by iteration_split_impl.
3097 if (!loop->_head->is_CountedLoop())
3098 return;
3099 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3100 return;
3101
3102 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3103 CountedLoopEndNode *cle = cl->loopexit();
3104 Node *exit = cle->proj_out(false);
3105 Node *phi = cl->phi();
3106
3107 // Check for the special case of folks using the pre-incremented
3108 // trip-counter on the fall-out path (forces the pre-incremented
3109 // and post-incremented trip counter to be live at the same time).
3110 // Fix this by adjusting to use the post-increment trip counter.
3111
3112 bool progress = true;
3113 while (progress) {
3114 progress = false;
3115 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3116 Node* use = phi->fast_out(i); // User of trip-counter
3117 if (!has_ctrl(use)) continue;
3118 Node *u_ctrl = get_ctrl(use);
3119 if (use->is_Phi()) {
3120 u_ctrl = NULL;
3121 for (uint j = 1; j < use->req(); j++)
3122 if (use->in(j) == phi)
3123 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3124 }
3125 IdealLoopTree *u_loop = get_loop(u_ctrl);
3126 // Look for loop-invariant use
3127 if (u_loop == loop) continue;
3128 if (loop->is_member(u_loop)) continue;
3129 // Check that use is live out the bottom. Assuming the trip-counter
3130 // update is right at the bottom, uses of of the loop middle are ok.
3131 if (dom_lca(exit, u_ctrl) != exit) continue;
3132 // Hit! Refactor use to use the post-incremented tripcounter.
3133 // Compute a post-increment tripcounter.
3134 Node *opaq = new Opaque2Node( C, cle->incr() );
3135 register_new_node(opaq, exit);
3136 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3137 set_ctrl(neg_stride, C->root());
3138 Node *post = new AddINode( opaq, neg_stride);
3139 register_new_node(post, exit);
3140 _igvn.rehash_node_delayed(use);
3141 for (uint j = 1; j < use->req(); j++) {
3142 if (use->in(j) == phi)
3143 use->set_req(j, post);
3144 }
3145 // Since DU info changed, rerun loop
3146 progress = true;
3147 break;
3148 }
3149 }
3150
3151 }