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