1 /*
2 * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/castnode.hpp"
30 #include "opto/connode.hpp"
31 #include "opto/castnode.hpp"
32 #include "opto/divnode.hpp"
33 #include "opto/loopnode.hpp"
34 #include "opto/matcher.hpp"
35 #include "opto/mulnode.hpp"
36 #include "opto/movenode.hpp"
37 #include "opto/opaquenode.hpp"
38 #include "opto/rootnode.hpp"
39 #include "opto/subnode.hpp"
40
41 //=============================================================================
42 //------------------------------split_thru_phi---------------------------------
43 // Split Node 'n' through merge point if there is enough win.
44 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
45 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
46 // ConvI2L may have type information on it which is unsafe to push up
47 // so disable this for now
48 return NULL;
49 }
50
51 // Splitting range check CastIIs through a loop induction Phi can
52 // cause new Phis to be created that are left unrelated to the loop
53 // induction Phi and prevent optimizations (vectorization)
54 if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
55 region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
56 return NULL;
57 }
58
59 int wins = 0;
60 assert(!n->is_CFG(), "");
61 assert(region->is_Region(), "");
62
63 const Type* type = n->bottom_type();
64 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
65 Node *phi;
66 if (t_oop != NULL && t_oop->is_known_instance_field()) {
67 int iid = t_oop->instance_id();
68 int index = C->get_alias_index(t_oop);
69 int offset = t_oop->offset();
70 phi = new PhiNode(region, type, NULL, iid, index, offset);
71 } else {
72 phi = PhiNode::make_blank(region, n);
73 }
74 uint old_unique = C->unique();
75 for (uint i = 1; i < region->req(); i++) {
76 Node *x;
77 Node* the_clone = NULL;
78 if (region->in(i) == C->top()) {
79 x = C->top(); // Dead path? Use a dead data op
80 } else {
81 x = n->clone(); // Else clone up the data op
82 the_clone = x; // Remember for possible deletion.
83 // Alter data node to use pre-phi inputs
84 if (n->in(0) == region)
85 x->set_req( 0, region->in(i) );
86 for (uint j = 1; j < n->req(); j++) {
87 Node *in = n->in(j);
88 if (in->is_Phi() && in->in(0) == region)
89 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
90 }
91 }
92 // Check for a 'win' on some paths
93 const Type *t = x->Value(&_igvn);
94
95 bool singleton = t->singleton();
96
97 // A TOP singleton indicates that there are no possible values incoming
98 // along a particular edge. In most cases, this is OK, and the Phi will
99 // be eliminated later in an Ideal call. However, we can't allow this to
100 // happen if the singleton occurs on loop entry, as the elimination of
101 // the PhiNode may cause the resulting node to migrate back to a previous
102 // loop iteration.
103 if (singleton && t == Type::TOP) {
104 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
105 // irreducible loop may not be indicated by an affirmative is_Loop());
106 // therefore, the only top we can split thru a phi is on a backedge of
107 // a loop.
108 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
109 }
110
111 if (singleton) {
112 wins++;
113 x = ((PhaseGVN&)_igvn).makecon(t);
114 } else {
115 // We now call Identity to try to simplify the cloned node.
116 // Note that some Identity methods call phase->type(this).
117 // Make sure that the type array is big enough for
118 // our new node, even though we may throw the node away.
119 // (Note: This tweaking with igvn only works because x is a new node.)
120 _igvn.set_type(x, t);
121 // If x is a TypeNode, capture any more-precise type permanently into Node
122 // otherwise it will be not updated during igvn->transform since
123 // igvn->type(x) is set to x->Value() already.
124 x->raise_bottom_type(t);
125 Node *y = x->Identity(&_igvn);
126 if (y != x) {
127 wins++;
128 x = y;
129 } else {
130 y = _igvn.hash_find(x);
131 if (y) {
132 wins++;
133 x = y;
134 } else {
135 // Else x is a new node we are keeping
136 // We do not need register_new_node_with_optimizer
137 // because set_type has already been called.
138 _igvn._worklist.push(x);
139 }
140 }
141 }
142 if (x != the_clone && the_clone != NULL)
143 _igvn.remove_dead_node(the_clone);
144 phi->set_req( i, x );
145 }
146 // Too few wins?
147 if (wins <= policy) {
148 _igvn.remove_dead_node(phi);
149 return NULL;
150 }
151
152 // Record Phi
153 register_new_node( phi, region );
154
155 for (uint i2 = 1; i2 < phi->req(); i2++) {
156 Node *x = phi->in(i2);
157 // If we commoned up the cloned 'x' with another existing Node,
158 // the existing Node picks up a new use. We need to make the
159 // existing Node occur higher up so it dominates its uses.
160 Node *old_ctrl;
161 IdealLoopTree *old_loop;
162
163 if (x->is_Con()) {
164 // Constant's control is always root.
165 set_ctrl(x, C->root());
166 continue;
167 }
168 // The occasional new node
169 if (x->_idx >= old_unique) { // Found a new, unplaced node?
170 old_ctrl = NULL;
171 old_loop = NULL; // Not in any prior loop
172 } else {
173 old_ctrl = get_ctrl(x);
174 old_loop = get_loop(old_ctrl); // Get prior loop
175 }
176 // New late point must dominate new use
177 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
178 if (new_ctrl == old_ctrl) // Nothing is changed
179 continue;
180
181 IdealLoopTree *new_loop = get_loop(new_ctrl);
182
183 // Don't move x into a loop if its uses are
184 // outside of loop. Otherwise x will be cloned
185 // for each use outside of this loop.
186 IdealLoopTree *use_loop = get_loop(region);
187 if (!new_loop->is_member(use_loop) &&
188 (old_loop == NULL || !new_loop->is_member(old_loop))) {
189 // Take early control, later control will be recalculated
190 // during next iteration of loop optimizations.
191 new_ctrl = get_early_ctrl(x);
192 new_loop = get_loop(new_ctrl);
193 }
194 // Set new location
195 set_ctrl(x, new_ctrl);
196 // If changing loop bodies, see if we need to collect into new body
197 if (old_loop != new_loop) {
198 if (old_loop && !old_loop->_child)
199 old_loop->_body.yank(x);
200 if (!new_loop->_child)
201 new_loop->_body.push(x); // Collect body info
202 }
203 }
204
205 return phi;
206 }
207
208 //------------------------------dominated_by------------------------------------
209 // Replace the dominated test with an obvious true or false. Place it on the
210 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
211 // live path up to the dominating control.
212 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
213 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
214
215 // prevdom is the dominating projection of the dominating test.
216 assert( iff->is_If(), "" );
217 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
218 int pop = prevdom->Opcode();
219 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
220 if (flip) {
221 if (pop == Op_IfTrue)
222 pop = Op_IfFalse;
223 else
224 pop = Op_IfTrue;
225 }
226 // 'con' is set to true or false to kill the dominated test.
227 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
228 set_ctrl(con, C->root()); // Constant gets a new use
229 // Hack the dominated test
230 _igvn.replace_input_of(iff, 1, con);
231
232 // If I dont have a reachable TRUE and FALSE path following the IfNode then
233 // I can assume this path reaches an infinite loop. In this case it's not
234 // important to optimize the data Nodes - either the whole compilation will
235 // be tossed or this path (and all data Nodes) will go dead.
236 if (iff->outcnt() != 2) return;
237
238 // Make control-dependent data Nodes on the live path (path that will remain
239 // once the dominated IF is removed) become control-dependent on the
240 // dominating projection.
241 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
242
243 // Loop predicates may have depending checks which should not
244 // be skipped. For example, range check predicate has two checks
245 // for lower and upper bounds.
246 if (dp == NULL)
247 return;
248
249 ProjNode* dp_proj = dp->as_Proj();
250 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
251 if (exclude_loop_predicate &&
252 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
253 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
254 // If this is a range check (IfNode::is_range_check), do not
255 // reorder because Compile::allow_range_check_smearing might have
256 // changed the check.
257 return; // Let IGVN transformation change control dependence.
258 }
259
260 IdealLoopTree *old_loop = get_loop(dp);
261
262 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
263 Node* cd = dp->fast_out(i); // Control-dependent node
264 if (cd->depends_only_on_test()) {
265 assert(cd->in(0) == dp, "");
266 _igvn.replace_input_of(cd, 0, prevdom);
267 set_early_ctrl(cd);
268 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
269 if (old_loop != new_loop) {
270 if (!old_loop->_child) old_loop->_body.yank(cd);
271 if (!new_loop->_child) new_loop->_body.push(cd);
272 }
273 --i;
274 --imax;
275 }
276 }
277 }
278
279 //------------------------------has_local_phi_input----------------------------
280 // Return TRUE if 'n' has Phi inputs from its local block and no other
281 // block-local inputs (all non-local-phi inputs come from earlier blocks)
282 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
283 Node *n_ctrl = get_ctrl(n);
284 // See if some inputs come from a Phi in this block, or from before
285 // this block.
286 uint i;
287 for( i = 1; i < n->req(); i++ ) {
288 Node *phi = n->in(i);
289 if( phi->is_Phi() && phi->in(0) == n_ctrl )
290 break;
291 }
292 if( i >= n->req() )
293 return NULL; // No Phi inputs; nowhere to clone thru
294
295 // Check for inputs created between 'n' and the Phi input. These
296 // must split as well; they have already been given the chance
297 // (courtesy of a post-order visit) and since they did not we must
298 // recover the 'cost' of splitting them by being very profitable
299 // when splitting 'n'. Since this is unlikely we simply give up.
300 for( i = 1; i < n->req(); i++ ) {
301 Node *m = n->in(i);
302 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
303 // We allow the special case of AddP's with no local inputs.
304 // This allows us to split-up address expressions.
305 if (m->is_AddP() &&
306 get_ctrl(m->in(2)) != n_ctrl &&
307 get_ctrl(m->in(3)) != n_ctrl) {
308 // Move the AddP up to dominating point
309 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
310 continue;
311 }
312 return NULL;
313 }
314 }
315
316 return n_ctrl;
317 }
318
319 //------------------------------remix_address_expressions----------------------
320 // Rework addressing expressions to get the most loop-invariant stuff
321 // moved out. We'd like to do all associative operators, but it's especially
322 // important (common) to do address expressions.
323 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
324 if (!has_ctrl(n)) return NULL;
325 Node *n_ctrl = get_ctrl(n);
326 IdealLoopTree *n_loop = get_loop(n_ctrl);
327
328 // See if 'n' mixes loop-varying and loop-invariant inputs and
329 // itself is loop-varying.
330
331 // Only interested in binary ops (and AddP)
332 if( n->req() < 3 || n->req() > 4 ) return NULL;
333
334 Node *n1_ctrl = get_ctrl(n->in( 1));
335 Node *n2_ctrl = get_ctrl(n->in( 2));
336 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
337 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
338 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
339 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
340
341 // Does one of my inputs spin in a tighter loop than self?
342 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
343 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
344 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
345 return NULL; // Leave well enough alone
346
347 // Is at least one of my inputs loop-invariant?
348 if( n1_loop == n_loop &&
349 n2_loop == n_loop &&
350 n3_loop == n_loop )
351 return NULL; // No loop-invariant inputs
352
353
354 int n_op = n->Opcode();
355
356 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
357 if( n_op == Op_LShiftI ) {
358 // Scale is loop invariant
359 Node *scale = n->in(2);
360 Node *scale_ctrl = get_ctrl(scale);
361 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
362 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
363 return NULL;
364 const TypeInt *scale_t = scale->bottom_type()->isa_int();
365 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
366 return NULL; // Dont bother with byte/short masking
367 // Add must vary with loop (else shift would be loop-invariant)
368 Node *add = n->in(1);
369 Node *add_ctrl = get_ctrl(add);
370 IdealLoopTree *add_loop = get_loop(add_ctrl);
371 //assert( n_loop == add_loop, "" );
372 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
373
374 // Convert I-V into I+ (0-V); same for V-I
375 if( add->Opcode() == Op_SubI &&
376 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
377 Node *zero = _igvn.intcon(0);
378 set_ctrl(zero, C->root());
379 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
380 register_new_node( neg, get_ctrl(add->in(2) ) );
381 add = new AddINode( add->in(1), neg );
382 register_new_node( add, add_ctrl );
383 }
384 if( add->Opcode() != Op_AddI ) return NULL;
385 // See if one add input is loop invariant
386 Node *add_var = add->in(1);
387 Node *add_var_ctrl = get_ctrl(add_var);
388 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
389 Node *add_invar = add->in(2);
390 Node *add_invar_ctrl = get_ctrl(add_invar);
391 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
392 if( add_var_loop == n_loop ) {
393 } else if( add_invar_loop == n_loop ) {
394 // Swap to find the invariant part
395 add_invar = add_var;
396 add_invar_ctrl = add_var_ctrl;
397 add_invar_loop = add_var_loop;
398 add_var = add->in(2);
399 Node *add_var_ctrl = get_ctrl(add_var);
400 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
401 } else // Else neither input is loop invariant
402 return NULL;
403 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
404 return NULL; // No invariant part of the add?
405
406 // Yes! Reshape address expression!
407 Node *inv_scale = new LShiftINode( add_invar, scale );
408 Node *inv_scale_ctrl =
409 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
410 add_invar_ctrl : scale_ctrl;
411 register_new_node( inv_scale, inv_scale_ctrl );
412 Node *var_scale = new LShiftINode( add_var, scale );
413 register_new_node( var_scale, n_ctrl );
414 Node *var_add = new AddINode( var_scale, inv_scale );
415 register_new_node( var_add, n_ctrl );
416 _igvn.replace_node( n, var_add );
417 return var_add;
418 }
419
420 // Replace (I+V) with (V+I)
421 if( n_op == Op_AddI ||
422 n_op == Op_AddL ||
423 n_op == Op_AddF ||
424 n_op == Op_AddD ||
425 n_op == Op_MulI ||
426 n_op == Op_MulL ||
427 n_op == Op_MulF ||
428 n_op == Op_MulD ) {
429 if( n2_loop == n_loop ) {
430 assert( n1_loop != n_loop, "" );
431 n->swap_edges(1, 2);
432 }
433 }
434
435 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
436 // but not if I2 is a constant.
437 if( n_op == Op_AddP ) {
438 if( n2_loop == n_loop && n3_loop != n_loop ) {
439 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
440 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
441 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
442 IdealLoopTree *n22loop = get_loop( n22_ctrl );
443 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
444 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
445 n23_loop == n_loop ) {
446 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
447 // Stuff new AddP in the loop preheader
448 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
449 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
450 register_new_node( add2, n_ctrl );
451 _igvn.replace_node( n, add2 );
452 return add2;
453 }
454 }
455 }
456
457 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
458 if (n2_loop != n_loop && n3_loop == n_loop) {
459 if (n->in(3)->Opcode() == Op_AddX) {
460 Node *V = n->in(3)->in(1);
461 Node *I = n->in(3)->in(2);
462 if (is_member(n_loop,get_ctrl(V))) {
463 } else {
464 Node *tmp = V; V = I; I = tmp;
465 }
466 if (!is_member(n_loop,get_ctrl(I))) {
467 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
468 // Stuff new AddP in the loop preheader
469 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
470 Node *add2 = new AddPNode(n->in(1), add1, V);
471 register_new_node(add2, n_ctrl);
472 _igvn.replace_node(n, add2);
473 return add2;
474 }
475 }
476 }
477 }
478
479 return NULL;
480 }
481
482 //------------------------------conditional_move-------------------------------
483 // Attempt to replace a Phi with a conditional move. We have some pretty
484 // strict profitability requirements. All Phis at the merge point must
485 // be converted, so we can remove the control flow. We need to limit the
486 // number of c-moves to a small handful. All code that was in the side-arms
487 // of the CFG diamond is now speculatively executed. This code has to be
488 // "cheap enough". We are pretty much limited to CFG diamonds that merge
489 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
490 Node *PhaseIdealLoop::conditional_move( Node *region ) {
491
492 assert(region->is_Region(), "sanity check");
493 if (region->req() != 3) return NULL;
494
495 // Check for CFG diamond
496 Node *lp = region->in(1);
497 Node *rp = region->in(2);
498 if (!lp || !rp) return NULL;
499 Node *lp_c = lp->in(0);
500 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
501 IfNode *iff = lp_c->as_If();
502
503 // Check for ops pinned in an arm of the diamond.
504 // Can't remove the control flow in this case
505 if (lp->outcnt() > 1) return NULL;
506 if (rp->outcnt() > 1) return NULL;
507
508 IdealLoopTree* r_loop = get_loop(region);
509 assert(r_loop == get_loop(iff), "sanity");
510 // Always convert to CMOVE if all results are used only outside this loop.
511 bool used_inside_loop = (r_loop == _ltree_root);
512
513 // Check profitability
514 int cost = 0;
515 int phis = 0;
516 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
517 Node *out = region->fast_out(i);
518 if (!out->is_Phi()) continue; // Ignore other control edges, etc
519 phis++;
520 PhiNode* phi = out->as_Phi();
521 BasicType bt = phi->type()->basic_type();
522 switch (bt) {
523 case T_DOUBLE:
524 if (C->use_cmove()) {
525 continue; //TODO: maybe we want to add some cost
526 }
527 case T_FLOAT: {
528 cost += Matcher::float_cmove_cost(); // Could be very expensive
529 break;
530 }
531 case T_LONG: {
532 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
533 }
534 case T_INT: // These all CMOV fine
535 case T_ADDRESS: { // (RawPtr)
536 cost++;
537 break;
538 }
539 case T_NARROWOOP: // Fall through
540 case T_OBJECT: { // Base oops are OK, but not derived oops
541 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
542 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
543 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
544 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
545 // have a Phi for the base here that we convert to a CMOVE all is well
546 // and good. But if the base is dead, we'll not make a CMOVE. Later
547 // the allocator will have to produce a base by creating a CMOVE of the
548 // relevant bases. This puts the allocator in the business of
549 // manufacturing expensive instructions, generally a bad plan.
550 // Just Say No to Conditionally-Moved Derived Pointers.
551 if (tp && tp->offset() != 0)
552 return NULL;
553 cost++;
554 break;
555 }
556 default:
557 return NULL; // In particular, can't do memory or I/O
558 }
559 // Add in cost any speculative ops
560 for (uint j = 1; j < region->req(); j++) {
561 Node *proj = region->in(j);
562 Node *inp = phi->in(j);
563 if (get_ctrl(inp) == proj) { // Found local op
564 cost++;
565 // Check for a chain of dependent ops; these will all become
566 // speculative in a CMOV.
567 for (uint k = 1; k < inp->req(); k++)
568 if (get_ctrl(inp->in(k)) == proj)
569 cost += ConditionalMoveLimit; // Too much speculative goo
570 }
571 }
572 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
573 // This will likely Split-If, a higher-payoff operation.
574 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
575 Node* use = phi->fast_out(k);
576 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
577 cost += ConditionalMoveLimit;
578 // Is there a use inside the loop?
579 // Note: check only basic types since CMoveP is pinned.
580 if (!used_inside_loop && is_java_primitive(bt)) {
581 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
582 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
583 used_inside_loop = true;
584 }
585 }
586 }
587 }//for
588 Node* bol = iff->in(1);
589 assert(bol->Opcode() == Op_Bool, "");
590 int cmp_op = bol->in(1)->Opcode();
591 // It is expensive to generate flags from a float compare.
592 // Avoid duplicated float compare.
593 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
594
595 float infrequent_prob = PROB_UNLIKELY_MAG(3);
596 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
597 if (used_inside_loop) {
598 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
599
600 // BlockLayoutByFrequency optimization moves infrequent branch
601 // from hot path. No point in CMOV'ing in such case (110 is used
602 // instead of 100 to take into account not exactness of float value).
603 if (BlockLayoutByFrequency) {
604 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
605 }
606 }
607 // Check for highly predictable branch. No point in CMOV'ing if
608 // we are going to predict accurately all the time.
609 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
610 else if (iff->_prob < infrequent_prob ||
611 iff->_prob > (1.0f - infrequent_prob))
612 return NULL;
613
614 // --------------
615 // Now replace all Phis with CMOV's
616 Node *cmov_ctrl = iff->in(0);
617 uint flip = (lp->Opcode() == Op_IfTrue);
618 while (1) {
619 PhiNode* phi = NULL;
620 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
621 Node *out = region->fast_out(i);
622 if (out->is_Phi()) {
623 phi = out->as_Phi();
624 break;
625 }
626 }
627 if (phi == NULL) break;
628 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
629 // Move speculative ops
630 for (uint j = 1; j < region->req(); j++) {
631 Node *proj = region->in(j);
632 Node *inp = phi->in(j);
633 if (get_ctrl(inp) == proj) { // Found local op
634 #ifndef PRODUCT
635 if (PrintOpto && VerifyLoopOptimizations) {
636 tty->print(" speculate: ");
637 inp->dump();
638 }
639 #endif
640 set_ctrl(inp, cmov_ctrl);
641 }
642 }
643 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
644 register_new_node( cmov, cmov_ctrl );
645 _igvn.replace_node( phi, cmov );
646 #ifndef PRODUCT
647 if (TraceLoopOpts) {
648 tty->print("CMOV ");
649 r_loop->dump_head();
650 if (Verbose) {
651 bol->in(1)->dump(1);
652 cmov->dump(1);
653 }
654 }
655 if (VerifyLoopOptimizations) verify();
656 #endif
657 }
658
659 // The useless CFG diamond will fold up later; see the optimization in
660 // RegionNode::Ideal.
661 _igvn._worklist.push(region);
662
663 return iff->in(1);
664 }
665
666 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
667 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
668 Node* u = m->fast_out(i);
669 if (u->is_CFG()) {
670 if (u->Opcode() == Op_NeverBranch) {
671 u = ((NeverBranchNode*)u)->proj_out(0);
672 enqueue_cfg_uses(u, wq);
673 } else {
674 wq.push(u);
675 }
676 }
677 }
678 }
679
680 // Try moving a store out of a loop, right before the loop
681 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
682 // Store has to be first in the loop body
683 IdealLoopTree *n_loop = get_loop(n_ctrl);
684 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
685 Node* address = n->in(MemNode::Address);
686 Node* value = n->in(MemNode::ValueIn);
687 Node* mem = n->in(MemNode::Memory);
688 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
689 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
690
691 // - address and value must be loop invariant
692 // - memory must be a memory Phi for the loop
693 // - Store must be the only store on this memory slice in the
694 // loop: if there's another store following this one then value
695 // written at iteration i by the second store could be overwritten
696 // at iteration i+n by the first store: it's not safe to move the
697 // first store out of the loop
698 // - nothing must observe the memory Phi: it guarantees no read
699 // before the store, we are also guaranteed the store post
700 // dominates the loop head (ignoring a possible early
701 // exit). Otherwise there would be extra Phi involved between the
702 // loop's Phi and the store.
703 // - there must be no early exit from the loop before the Store
704 // (such an exit most of the time would be an extra use of the
705 // memory Phi but sometimes is a bottom memory Phi that takes the
706 // store as input).
707
708 if (!n_loop->is_member(address_loop) &&
709 !n_loop->is_member(value_loop) &&
710 mem->is_Phi() && mem->in(0) == n_loop->_head &&
711 mem->outcnt() == 1 &&
712 mem->in(LoopNode::LoopBackControl) == n) {
713
714 assert(n_loop->_tail != NULL, "need a tail");
715 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
716
717 // Verify that there's no early exit of the loop before the store.
718 bool ctrl_ok = false;
719 {
720 // Follow control from loop head until n, we exit the loop or
721 // we reach the tail
722 ResourceMark rm;
723 Unique_Node_List wq;
724 wq.push(n_loop->_head);
725
726 for (uint next = 0; next < wq.size(); ++next) {
727 Node *m = wq.at(next);
728 if (m == n->in(0)) {
729 ctrl_ok = true;
730 continue;
731 }
732 assert(!has_ctrl(m), "should be CFG");
733 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
734 ctrl_ok = false;
735 break;
736 }
737 enqueue_cfg_uses(m, wq);
738 if (wq.size() > 10) {
739 ctrl_ok = false;
740 break;
741 }
742 }
743 }
744 if (ctrl_ok) {
745 // move the Store
746 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
747 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
748 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
749 // Disconnect the phi now. An empty phi can confuse other
750 // optimizations in this pass of loop opts.
751 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
752 n_loop->_body.yank(mem);
753
754 IdealLoopTree* new_loop = get_loop(n->in(0));
755 set_ctrl_and_loop(n, n->in(0));
756
757 return n;
758 }
759 }
760 }
761 return NULL;
762 }
763
764 // Try moving a store out of a loop, right after the loop
765 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
766 if (n->is_Store() && n->in(0) != NULL) {
767 Node *n_ctrl = get_ctrl(n);
768 IdealLoopTree *n_loop = get_loop(n_ctrl);
769 // Store must be in a loop
770 if (n_loop != _ltree_root && !n_loop->_irreducible) {
771 Node* address = n->in(MemNode::Address);
772 Node* value = n->in(MemNode::ValueIn);
773 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
774 // address must be loop invariant
775 if (!n_loop->is_member(address_loop)) {
776 // Store must be last on this memory slice in the loop and
777 // nothing in the loop must observe it
778 Node* phi = NULL;
779 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
780 Node* u = n->fast_out(i);
781 if (has_ctrl(u)) { // control use?
782 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
783 if (!n_loop->is_member(u_loop)) {
784 continue;
785 }
786 if (u->is_Phi() && u->in(0) == n_loop->_head) {
787 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
788 // multiple phis on the same slice are possible
789 if (phi != NULL) {
790 return;
791 }
792 phi = u;
793 continue;
794 }
795 }
796 return;
797 }
798 if (phi != NULL) {
799 // Nothing in the loop before the store (next iteration)
800 // must observe the stored value
801 bool mem_ok = true;
802 {
803 ResourceMark rm;
804 Unique_Node_List wq;
805 wq.push(phi);
806 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
807 Node *m = wq.at(next);
808 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
809 Node* u = m->fast_out(i);
810 if (u->is_Store() || u->is_Phi()) {
811 if (u != n) {
812 wq.push(u);
813 mem_ok = (wq.size() <= 10);
814 }
815 } else {
816 mem_ok = false;
817 break;
818 }
819 }
820 }
821 }
822 if (mem_ok) {
823 // Move the Store out of the loop creating clones along
824 // all paths out of the loop that observe the stored value
825 _igvn.rehash_node_delayed(phi);
826 int count = phi->replace_edge(n, n->in(MemNode::Memory));
827 assert(count > 0, "inconsistent phi");
828 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
829 Node* u = n->fast_out(i);
830 Node* c = get_ctrl(u);
831
832 if (u->is_Phi()) {
833 c = u->in(0)->in(u->find_edge(n));
834 }
835 IdealLoopTree *u_loop = get_loop(c);
836 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
837 while(true) {
838 Node* next_c = find_non_split_ctrl(idom(c));
839 if (n_loop->is_member(get_loop(next_c))) {
840 break;
841 }
842 c = next_c;
843 }
844
845 Node* st = n->clone();
846 st->set_req(0, c);
847 _igvn.register_new_node_with_optimizer(st);
848
849 set_ctrl(st, c);
850 IdealLoopTree* new_loop = get_loop(c);
851 assert(new_loop != n_loop, "should be moved out of loop");
852 if (new_loop->_child == NULL) new_loop->_body.push(st);
853
854 _igvn.replace_input_of(u, u->find_edge(n), st);
855 --imax;
856 --i;
857 }
858
859
860 assert(n->outcnt() == 0, "all uses should be gone");
861 _igvn.replace_input_of(n, MemNode::Memory, C->top());
862 // Disconnect the phi now. An empty phi can confuse other
863 // optimizations in this pass of loop opts..
864 if (phi->in(LoopNode::LoopBackControl) == phi) {
865 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
866 n_loop->_body.yank(phi);
867 }
868 }
869 }
870 }
871 }
872 }
873 }
874
875 //------------------------------split_if_with_blocks_pre-----------------------
876 // Do the real work in a non-recursive function. Data nodes want to be
877 // cloned in the pre-order so they can feed each other nicely.
878 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
879 // Cloning these guys is unlikely to win
880 int n_op = n->Opcode();
881 if( n_op == Op_MergeMem ) return n;
882 if( n->is_Proj() ) return n;
883 // Do not clone-up CmpFXXX variations, as these are always
884 // followed by a CmpI
885 if( n->is_Cmp() ) return n;
886 // Attempt to use a conditional move instead of a phi/branch
887 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
888 Node *cmov = conditional_move( n );
889 if( cmov ) return cmov;
890 }
891 if( n->is_CFG() || n->is_LoadStore() )
892 return n;
893 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
894 n_op == Op_Opaque2 ) {
895 if( !C->major_progress() ) // If chance of no more loop opts...
896 _igvn._worklist.push(n); // maybe we'll remove them
897 return n;
898 }
899
900 if( n->is_Con() ) return n; // No cloning for Con nodes
901
902 Node *n_ctrl = get_ctrl(n);
903 if( !n_ctrl ) return n; // Dead node
904
905 Node* res = try_move_store_before_loop(n, n_ctrl);
906 if (res != NULL) {
907 return n;
908 }
909
910 // Attempt to remix address expressions for loop invariants
911 Node *m = remix_address_expressions( n );
912 if( m ) return m;
913
914 if (n->is_ConstraintCast()) {
915 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(this);
916 if (dom_cast != NULL) {
917 _igvn.replace_node(n, dom_cast);
918 return dom_cast;
919 }
920 }
921
922 // Determine if the Node has inputs from some local Phi.
923 // Returns the block to clone thru.
924 Node *n_blk = has_local_phi_input( n );
925 if( !n_blk ) return n;
926
927 // Do not clone the trip counter through on a CountedLoop
928 // (messes up the canonical shape).
929 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
930
931 // Check for having no control input; not pinned. Allow
932 // dominating control.
933 if (n->in(0)) {
934 Node *dom = idom(n_blk);
935 if (dom_lca(n->in(0), dom) != n->in(0)) {
936 return n;
937 }
938 }
939 // Policy: when is it profitable. You must get more wins than
940 // policy before it is considered profitable. Policy is usually 0,
941 // so 1 win is considered profitable. Big merges will require big
942 // cloning, so get a larger policy.
943 int policy = n_blk->req() >> 2;
944
945 // If the loop is a candidate for range check elimination,
946 // delay splitting through it's phi until a later loop optimization
947 if (n_blk->is_CountedLoop()) {
948 IdealLoopTree *lp = get_loop(n_blk);
949 if (lp && lp->_rce_candidate) {
950 return n;
951 }
952 }
953
954 // Use same limit as split_if_with_blocks_post
955 if( C->live_nodes() > 35000 ) return n; // Method too big
956
957 // Split 'n' through the merge point if it is profitable
958 Node *phi = split_thru_phi( n, n_blk, policy );
959 if (!phi) return n;
960
961 // Found a Phi to split thru!
962 // Replace 'n' with the new phi
963 _igvn.replace_node( n, phi );
964 // Moved a load around the loop, 'en-registering' something.
965 if (n_blk->is_Loop() && n->is_Load() &&
966 !phi->in(LoopNode::LoopBackControl)->is_Load())
967 C->set_major_progress();
968
969 return phi;
970 }
971
972 static bool merge_point_too_heavy(Compile* C, Node* region) {
973 // Bail out if the region and its phis have too many users.
974 int weight = 0;
975 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
976 weight += region->fast_out(i)->outcnt();
977 }
978 int nodes_left = C->max_node_limit() - C->live_nodes();
979 if (weight * 8 > nodes_left) {
980 if (PrintOpto) {
981 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
982 }
983 return true;
984 } else {
985 return false;
986 }
987 }
988
989 static bool merge_point_safe(Node* region) {
990 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
991 // having a PhiNode input. This sidesteps the dangerous case where the split
992 // ConvI2LNode may become TOP if the input Value() does not
993 // overlap the ConvI2L range, leaving a node which may not dominate its
994 // uses.
995 // A better fix for this problem can be found in the BugTraq entry, but
996 // expediency for Mantis demands this hack.
997 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
998 // split_if_with_blocks from splitting a block because we could not move around
999 // the FastLockNode.
1000 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1001 Node* n = region->fast_out(i);
1002 if (n->is_Phi()) {
1003 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1004 Node* m = n->fast_out(j);
1005 if (m->is_FastLock())
1006 return false;
1007 #ifdef _LP64
1008 if (m->Opcode() == Op_ConvI2L)
1009 return false;
1010 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1011 return false;
1012 }
1013 #endif
1014 }
1015 }
1016 }
1017 return true;
1018 }
1019
1020
1021 //------------------------------place_near_use---------------------------------
1022 // Place some computation next to use but not inside inner loops.
1023 // For inner loop uses move it to the preheader area.
1024 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1025 IdealLoopTree *u_loop = get_loop( useblock );
1026 return (u_loop->_irreducible || u_loop->_child)
1027 ? useblock
1028 : u_loop->_head->in(LoopNode::EntryControl);
1029 }
1030
1031
1032 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1033 if (!n->is_If()) {
1034 return false;
1035 }
1036 if (!n->in(0)->is_Region()) {
1037 return false;
1038 }
1039 Node* region = n->in(0);
1040 Node* dom = idom(region);
1041 if (!dom->is_If() || dom->in(1) != n->in(1)) {
1042 return false;
1043 }
1044 IfNode* dom_if = dom->as_If();
1045 Node* proj_true = dom_if->proj_out(1);
1046 Node* proj_false = dom_if->proj_out(0);
1047
1048 for (uint i = 1; i < region->req(); i++) {
1049 if (is_dominator(proj_true, region->in(i))) {
1050 continue;
1051 }
1052 if (is_dominator(proj_false, region->in(i))) {
1053 continue;
1054 }
1055 return false;
1056 }
1057
1058 return true;
1059 }
1060
1061 bool PhaseIdealLoop::can_split_if(Node *n_ctrl) {
1062 if (C->live_nodes() > 35000) {
1063 return false; // Method too big
1064 }
1065
1066 // Do not do 'split-if' if irreducible loops are present.
1067 if (_has_irreducible_loops) {
1068 return false;
1069 }
1070
1071 if (merge_point_too_heavy(C, n_ctrl)) {
1072 return false;
1073 }
1074
1075 // Do not do 'split-if' if some paths are dead. First do dead code
1076 // elimination and then see if its still profitable.
1077 for (uint i = 1; i < n_ctrl->req(); i++) {
1078 if (n_ctrl->in(i) == C->top()) {
1079 return false;
1080 }
1081 }
1082
1083 // If trying to do a 'Split-If' at the loop head, it is only
1084 // profitable if the cmp folds up on BOTH paths. Otherwise we
1085 // risk peeling a loop forever.
1086
1087 // CNC - Disabled for now. Requires careful handling of loop
1088 // body selection for the cloned code. Also, make sure we check
1089 // for any input path not being in the same loop as n_ctrl. For
1090 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1091 // because the alternative loop entry points won't be converted
1092 // into LoopNodes.
1093 IdealLoopTree *n_loop = get_loop(n_ctrl);
1094 for (uint j = 1; j < n_ctrl->req(); j++) {
1095 if (get_loop(n_ctrl->in(j)) != n_loop) {
1096 return false;
1097 }
1098 }
1099
1100 // Check for safety of the merge point.
1101 if (!merge_point_safe(n_ctrl)) {
1102 return false;
1103 }
1104
1105 return true;
1106 }
1107
1108 //------------------------------split_if_with_blocks_post----------------------
1109 // Do the real work in a non-recursive function. CFG hackery wants to be
1110 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1111 // info.
1112 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1113
1114 // Cloning Cmp through Phi's involves the split-if transform.
1115 // FastLock is not used by an If
1116 if (n->is_Cmp() && !n->is_FastLock()) {
1117 Node *n_ctrl = get_ctrl(n);
1118 // Determine if the Node has inputs from some local Phi.
1119 // Returns the block to clone thru.
1120 Node *n_blk = has_local_phi_input(n);
1121 if (n_blk != n_ctrl) {
1122 return;
1123 }
1124
1125 if (!can_split_if(n_ctrl)) {
1126 return;
1127 }
1128
1129 if (n->outcnt() != 1) {
1130 return; // Multiple bool's from 1 compare?
1131 }
1132 Node *bol = n->unique_out();
1133 assert(bol->is_Bool(), "expect a bool here");
1134 if (bol->outcnt() != 1) {
1135 return;// Multiple branches from 1 compare?
1136 }
1137 Node *iff = bol->unique_out();
1138
1139 // Check some safety conditions
1140 if (iff->is_If()) { // Classic split-if?
1141 if (iff->in(0) != n_ctrl) {
1142 return; // Compare must be in same blk as if
1143 }
1144 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1145 // Can't split CMove with different control edge.
1146 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1147 return;
1148 }
1149 if (get_ctrl(iff->in(2)) == n_ctrl ||
1150 get_ctrl(iff->in(3)) == n_ctrl) {
1151 return; // Inputs not yet split-up
1152 }
1153 if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1154 return; // Loop-invar test gates loop-varying CMOVE
1155 }
1156 } else {
1157 return; // some other kind of node, such as an Allocate
1158 }
1159
1160 // When is split-if profitable? Every 'win' on means some control flow
1161 // goes dead, so it's almost always a win.
1162 int policy = 0;
1163 // Split compare 'n' through the merge point if it is profitable
1164 Node *phi = split_thru_phi( n, n_ctrl, policy);
1165 if (!phi) {
1166 return;
1167 }
1168
1169 // Found a Phi to split thru!
1170 // Replace 'n' with the new phi
1171 _igvn.replace_node(n, phi);
1172
1173 // Now split the bool up thru the phi
1174 Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1175 guarantee(bolphi != NULL, "null boolean phi node");
1176
1177 _igvn.replace_node(bol, bolphi);
1178 assert(iff->in(1) == bolphi, "");
1179
1180 if (bolphi->Value(&_igvn)->singleton()) {
1181 return;
1182 }
1183
1184 // Conditional-move? Must split up now
1185 if (!iff->is_If()) {
1186 Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1187 _igvn.replace_node(iff, cmovphi);
1188 return;
1189 }
1190
1191 // Now split the IF
1192 do_split_if(iff);
1193 return;
1194 }
1195
1196 // Two identical ifs back to back can be merged
1197 if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1198 Node *n_ctrl = n->in(0);
1199 PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1200 IfNode* dom_if = idom(n_ctrl)->as_If();
1201 Node* proj_true = dom_if->proj_out(1);
1202 Node* proj_false = dom_if->proj_out(0);
1203 Node* con_true = _igvn.makecon(TypeInt::ONE);
1204 Node* con_false = _igvn.makecon(TypeInt::ZERO);
1205
1206 for (uint i = 1; i < n_ctrl->req(); i++) {
1207 if (is_dominator(proj_true, n_ctrl->in(i))) {
1208 bolphi->init_req(i, con_true);
1209 } else {
1210 assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1211 bolphi->init_req(i, con_false);
1212 }
1213 }
1214 register_new_node(bolphi, n_ctrl);
1215 _igvn.replace_input_of(n, 1, bolphi);
1216
1217 // Now split the IF
1218 do_split_if(n);
1219 return;
1220 }
1221
1222 // Check for an IF ready to split; one that has its
1223 // condition codes input coming from a Phi at the block start.
1224 int n_op = n->Opcode();
1225
1226 // Check for an IF being dominated by another IF same test
1227 if (n_op == Op_If ||
1228 n_op == Op_RangeCheck) {
1229 Node *bol = n->in(1);
1230 uint max = bol->outcnt();
1231 // Check for same test used more than once?
1232 if (max > 1 && bol->is_Bool()) {
1233 // Search up IDOMs to see if this IF is dominated.
1234 Node *cutoff = get_ctrl(bol);
1235
1236 // Now search up IDOMs till cutoff, looking for a dominating test
1237 Node *prevdom = n;
1238 Node *dom = idom(prevdom);
1239 while (dom != cutoff) {
1240 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1241 // Replace the dominated test with an obvious true or false.
1242 // Place it on the IGVN worklist for later cleanup.
1243 C->set_major_progress();
1244 dominated_by(prevdom, n, false, true);
1245 #ifndef PRODUCT
1246 if( VerifyLoopOptimizations ) verify();
1247 #endif
1248 return;
1249 }
1250 prevdom = dom;
1251 dom = idom(prevdom);
1252 }
1253 }
1254 }
1255
1256 // See if a shared loop-varying computation has no loop-varying uses.
1257 // Happens if something is only used for JVM state in uncommon trap exits,
1258 // like various versions of induction variable+offset. Clone the
1259 // computation per usage to allow it to sink out of the loop.
1260 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1261 Node *n_ctrl = get_ctrl(n);
1262 IdealLoopTree *n_loop = get_loop(n_ctrl);
1263 if( n_loop != _ltree_root ) {
1264 DUIterator_Fast imax, i = n->fast_outs(imax);
1265 for (; i < imax; i++) {
1266 Node* u = n->fast_out(i);
1267 if( !has_ctrl(u) ) break; // Found control user
1268 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1269 if( u_loop == n_loop ) break; // Found loop-varying use
1270 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1271 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1272 }
1273 bool did_break = (i < imax); // Did we break out of the previous loop?
1274 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1275 Node *late_load_ctrl = NULL;
1276 if (n->is_Load()) {
1277 // If n is a load, get and save the result from get_late_ctrl(),
1278 // to be later used in calculating the control for n's clones.
1279 clear_dom_lca_tags();
1280 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1281 }
1282 // If n is a load, and the late control is the same as the current
1283 // control, then the cloning of n is a pointless exercise, because
1284 // GVN will ensure that we end up where we started.
1285 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1286 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1287 Node *u = n->last_out(j); // Clone private computation per use
1288 _igvn.rehash_node_delayed(u);
1289 Node *x = n->clone(); // Clone computation
1290 Node *x_ctrl = NULL;
1291 if( u->is_Phi() ) {
1292 // Replace all uses of normal nodes. Replace Phi uses
1293 // individually, so the separate Nodes can sink down
1294 // different paths.
1295 uint k = 1;
1296 while( u->in(k) != n ) k++;
1297 u->set_req( k, x );
1298 // x goes next to Phi input path
1299 x_ctrl = u->in(0)->in(k);
1300 --j;
1301 } else { // Normal use
1302 // Replace all uses
1303 for( uint k = 0; k < u->req(); k++ ) {
1304 if( u->in(k) == n ) {
1305 u->set_req( k, x );
1306 --j;
1307 }
1308 }
1309 x_ctrl = get_ctrl(u);
1310 }
1311
1312 // Find control for 'x' next to use but not inside inner loops.
1313 // For inner loop uses get the preheader area.
1314 x_ctrl = place_near_use(x_ctrl);
1315
1316 if (n->is_Load()) {
1317 // For loads, add a control edge to a CFG node outside of the loop
1318 // to force them to not combine and return back inside the loop
1319 // during GVN optimization (4641526).
1320 //
1321 // Because we are setting the actual control input, factor in
1322 // the result from get_late_ctrl() so we respect any
1323 // anti-dependences. (6233005).
1324 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1325
1326 // Don't allow the control input to be a CFG splitting node.
1327 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1328 // should only have IfTrueNode and IfFalseNode (4985384).
1329 x_ctrl = find_non_split_ctrl(x_ctrl);
1330 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1331
1332 x->set_req(0, x_ctrl);
1333 }
1334 register_new_node(x, x_ctrl);
1335
1336 // Some institutional knowledge is needed here: 'x' is
1337 // yanked because if the optimizer runs GVN on it all the
1338 // cloned x's will common up and undo this optimization and
1339 // be forced back in the loop. This is annoying because it
1340 // makes +VerifyOpto report false-positives on progress. I
1341 // tried setting control edges on the x's to force them to
1342 // not combine, but the matching gets worried when it tries
1343 // to fold a StoreP and an AddP together (as part of an
1344 // address expression) and the AddP and StoreP have
1345 // different controls.
1346 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1347 }
1348 _igvn.remove_dead_node(n);
1349 }
1350 }
1351 }
1352 }
1353
1354 try_move_store_after_loop(n);
1355
1356 // Check for Opaque2's who's loop has disappeared - who's input is in the
1357 // same loop nest as their output. Remove 'em, they are no longer useful.
1358 if( n_op == Op_Opaque2 &&
1359 n->in(1) != NULL &&
1360 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1361 _igvn.replace_node( n, n->in(1) );
1362 }
1363 }
1364
1365 //------------------------------split_if_with_blocks---------------------------
1366 // Check for aggressive application of 'split-if' optimization,
1367 // using basic block level info.
1368 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1369 Node *n = C->root();
1370 visited.set(n->_idx); // first, mark node as visited
1371 // Do pre-visit work for root
1372 n = split_if_with_blocks_pre( n );
1373 uint cnt = n->outcnt();
1374 uint i = 0;
1375 while (true) {
1376 // Visit all children
1377 if (i < cnt) {
1378 Node* use = n->raw_out(i);
1379 ++i;
1380 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1381 // Now do pre-visit work for this use
1382 use = split_if_with_blocks_pre( use );
1383 nstack.push(n, i); // Save parent and next use's index.
1384 n = use; // Process all children of current use.
1385 cnt = use->outcnt();
1386 i = 0;
1387 }
1388 }
1389 else {
1390 // All of n's children have been processed, complete post-processing.
1391 if (cnt != 0 && !n->is_Con()) {
1392 assert(has_node(n), "no dead nodes");
1393 split_if_with_blocks_post( n );
1394 }
1395 if (nstack.is_empty()) {
1396 // Finished all nodes on stack.
1397 break;
1398 }
1399 // Get saved parent node and next use's index. Visit the rest of uses.
1400 n = nstack.node();
1401 cnt = n->outcnt();
1402 i = nstack.index();
1403 nstack.pop();
1404 }
1405 }
1406 }
1407
1408
1409 //=============================================================================
1410 //
1411 // C L O N E A L O O P B O D Y
1412 //
1413
1414 //------------------------------clone_iff--------------------------------------
1415 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1416 // "Nearly" because all Nodes have been cloned from the original in the loop,
1417 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1418 // through the Phi recursively, and return a Bool.
1419 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1420
1421 // Convert this Phi into a Phi merging Bools
1422 uint i;
1423 for( i = 1; i < phi->req(); i++ ) {
1424 Node *b = phi->in(i);
1425 if( b->is_Phi() ) {
1426 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1427 } else {
1428 assert( b->is_Bool(), "" );
1429 }
1430 }
1431
1432 Node *sample_bool = phi->in(1);
1433 Node *sample_cmp = sample_bool->in(1);
1434
1435 // Make Phis to merge the Cmp's inputs.
1436 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1437 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1438 for( i = 1; i < phi->req(); i++ ) {
1439 Node *n1 = phi->in(i)->in(1)->in(1);
1440 Node *n2 = phi->in(i)->in(1)->in(2);
1441 phi1->set_req( i, n1 );
1442 phi2->set_req( i, n2 );
1443 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1444 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1445 }
1446 // See if these Phis have been made before.
1447 // Register with optimizer
1448 Node *hit1 = _igvn.hash_find_insert(phi1);
1449 if( hit1 ) { // Hit, toss just made Phi
1450 _igvn.remove_dead_node(phi1); // Remove new phi
1451 assert( hit1->is_Phi(), "" );
1452 phi1 = (PhiNode*)hit1; // Use existing phi
1453 } else { // Miss
1454 _igvn.register_new_node_with_optimizer(phi1);
1455 }
1456 Node *hit2 = _igvn.hash_find_insert(phi2);
1457 if( hit2 ) { // Hit, toss just made Phi
1458 _igvn.remove_dead_node(phi2); // Remove new phi
1459 assert( hit2->is_Phi(), "" );
1460 phi2 = (PhiNode*)hit2; // Use existing phi
1461 } else { // Miss
1462 _igvn.register_new_node_with_optimizer(phi2);
1463 }
1464 // Register Phis with loop/block info
1465 set_ctrl(phi1, phi->in(0));
1466 set_ctrl(phi2, phi->in(0));
1467 // Make a new Cmp
1468 Node *cmp = sample_cmp->clone();
1469 cmp->set_req( 1, phi1 );
1470 cmp->set_req( 2, phi2 );
1471 _igvn.register_new_node_with_optimizer(cmp);
1472 set_ctrl(cmp, phi->in(0));
1473
1474 // Make a new Bool
1475 Node *b = sample_bool->clone();
1476 b->set_req(1,cmp);
1477 _igvn.register_new_node_with_optimizer(b);
1478 set_ctrl(b, phi->in(0));
1479
1480 assert( b->is_Bool(), "" );
1481 return (BoolNode*)b;
1482 }
1483
1484 //------------------------------clone_bool-------------------------------------
1485 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1486 // "Nearly" because all Nodes have been cloned from the original in the loop,
1487 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1488 // through the Phi recursively, and return a Bool.
1489 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1490 uint i;
1491 // Convert this Phi into a Phi merging Bools
1492 for( i = 1; i < phi->req(); i++ ) {
1493 Node *b = phi->in(i);
1494 if( b->is_Phi() ) {
1495 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1496 } else {
1497 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1498 }
1499 }
1500
1501 Node *sample_cmp = phi->in(1);
1502
1503 // Make Phis to merge the Cmp's inputs.
1504 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1505 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1506 for( uint j = 1; j < phi->req(); j++ ) {
1507 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1508 Node *n1, *n2;
1509 if( cmp_top->is_Cmp() ) {
1510 n1 = cmp_top->in(1);
1511 n2 = cmp_top->in(2);
1512 } else {
1513 n1 = n2 = cmp_top;
1514 }
1515 phi1->set_req( j, n1 );
1516 phi2->set_req( j, n2 );
1517 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1518 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1519 }
1520
1521 // See if these Phis have been made before.
1522 // Register with optimizer
1523 Node *hit1 = _igvn.hash_find_insert(phi1);
1524 if( hit1 ) { // Hit, toss just made Phi
1525 _igvn.remove_dead_node(phi1); // Remove new phi
1526 assert( hit1->is_Phi(), "" );
1527 phi1 = (PhiNode*)hit1; // Use existing phi
1528 } else { // Miss
1529 _igvn.register_new_node_with_optimizer(phi1);
1530 }
1531 Node *hit2 = _igvn.hash_find_insert(phi2);
1532 if( hit2 ) { // Hit, toss just made Phi
1533 _igvn.remove_dead_node(phi2); // Remove new phi
1534 assert( hit2->is_Phi(), "" );
1535 phi2 = (PhiNode*)hit2; // Use existing phi
1536 } else { // Miss
1537 _igvn.register_new_node_with_optimizer(phi2);
1538 }
1539 // Register Phis with loop/block info
1540 set_ctrl(phi1, phi->in(0));
1541 set_ctrl(phi2, phi->in(0));
1542 // Make a new Cmp
1543 Node *cmp = sample_cmp->clone();
1544 cmp->set_req( 1, phi1 );
1545 cmp->set_req( 2, phi2 );
1546 _igvn.register_new_node_with_optimizer(cmp);
1547 set_ctrl(cmp, phi->in(0));
1548
1549 assert( cmp->is_Cmp(), "" );
1550 return (CmpNode*)cmp;
1551 }
1552
1553 //------------------------------sink_use---------------------------------------
1554 // If 'use' was in the loop-exit block, it now needs to be sunk
1555 // below the post-loop merge point.
1556 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1557 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1558 set_ctrl(use, post_loop);
1559 for (DUIterator j = use->outs(); use->has_out(j); j++)
1560 sink_use(use->out(j), post_loop);
1561 }
1562 }
1563
1564 //------------------------------clone_loop-------------------------------------
1565 //
1566 // C L O N E A L O O P B O D Y
1567 //
1568 // This is the basic building block of the loop optimizations. It clones an
1569 // entire loop body. It makes an old_new loop body mapping; with this mapping
1570 // you can find the new-loop equivalent to an old-loop node. All new-loop
1571 // nodes are exactly equal to their old-loop counterparts, all edges are the
1572 // same. All exits from the old-loop now have a RegionNode that merges the
1573 // equivalent new-loop path. This is true even for the normal "loop-exit"
1574 // condition. All uses of loop-invariant old-loop values now come from (one
1575 // or more) Phis that merge their new-loop equivalents.
1576 //
1577 // This operation leaves the graph in an illegal state: there are two valid
1578 // control edges coming from the loop pre-header to both loop bodies. I'll
1579 // definitely have to hack the graph after running this transform.
1580 //
1581 // From this building block I will further edit edges to perform loop peeling
1582 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1583 //
1584 // Parameter side_by_size_idom:
1585 // When side_by_size_idom is NULL, the dominator tree is constructed for
1586 // the clone loop to dominate the original. Used in construction of
1587 // pre-main-post loop sequence.
1588 // When nonnull, the clone and original are side-by-side, both are
1589 // dominated by the side_by_side_idom node. Used in construction of
1590 // unswitched loops.
1591 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1592 Node* side_by_side_idom) {
1593
1594 if (C->do_vector_loop() && PrintOpto) {
1595 const char* mname = C->method()->name()->as_quoted_ascii();
1596 if (mname != NULL) {
1597 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1598 }
1599 }
1600
1601 CloneMap& cm = C->clone_map();
1602 Dict* dict = cm.dict();
1603 if (C->do_vector_loop()) {
1604 cm.set_clone_idx(cm.max_gen()+1);
1605 #ifndef PRODUCT
1606 if (PrintOpto) {
1607 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1608 loop->dump_head();
1609 }
1610 #endif
1611 }
1612
1613 // Step 1: Clone the loop body. Make the old->new mapping.
1614 uint i;
1615 for( i = 0; i < loop->_body.size(); i++ ) {
1616 Node *old = loop->_body.at(i);
1617 Node *nnn = old->clone();
1618 old_new.map( old->_idx, nnn );
1619 if (C->do_vector_loop()) {
1620 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1621 }
1622 _igvn.register_new_node_with_optimizer(nnn);
1623 }
1624
1625
1626 // Step 2: Fix the edges in the new body. If the old input is outside the
1627 // loop use it. If the old input is INside the loop, use the corresponding
1628 // new node instead.
1629 for( i = 0; i < loop->_body.size(); i++ ) {
1630 Node *old = loop->_body.at(i);
1631 Node *nnn = old_new[old->_idx];
1632 // Fix CFG/Loop controlling the new node
1633 if (has_ctrl(old)) {
1634 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1635 } else {
1636 set_loop(nnn, loop->_parent);
1637 if (old->outcnt() > 0) {
1638 set_idom( nnn, old_new[idom(old)->_idx], dd );
1639 }
1640 }
1641 // Correct edges to the new node
1642 for( uint j = 0; j < nnn->req(); j++ ) {
1643 Node *n = nnn->in(j);
1644 if( n ) {
1645 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1646 if( loop->is_member( old_in_loop ) )
1647 nnn->set_req(j, old_new[n->_idx]);
1648 }
1649 }
1650 _igvn.hash_find_insert(nnn);
1651 }
1652 Node *newhead = old_new[loop->_head->_idx];
1653 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1654
1655
1656 // Step 3: Now fix control uses. Loop varying control uses have already
1657 // been fixed up (as part of all input edges in Step 2). Loop invariant
1658 // control uses must be either an IfFalse or an IfTrue. Make a merge
1659 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1660 // refer to this.
1661 ResourceArea *area = Thread::current()->resource_area();
1662 Node_List worklist(area);
1663 uint new_counter = C->unique();
1664 for( i = 0; i < loop->_body.size(); i++ ) {
1665 Node* old = loop->_body.at(i);
1666 if( !old->is_CFG() ) continue;
1667 Node* nnn = old_new[old->_idx];
1668
1669 // Copy uses to a worklist, so I can munge the def-use info
1670 // with impunity.
1671 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1672 worklist.push(old->fast_out(j));
1673
1674 while( worklist.size() ) { // Visit all uses
1675 Node *use = worklist.pop();
1676 if (!has_node(use)) continue; // Ignore dead nodes
1677 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1678 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1679 // Both OLD and USE are CFG nodes here.
1680 assert( use->is_Proj(), "" );
1681
1682 // Clone the loop exit control projection
1683 Node *newuse = use->clone();
1684 if (C->do_vector_loop()) {
1685 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1686 }
1687 newuse->set_req(0,nnn);
1688 _igvn.register_new_node_with_optimizer(newuse);
1689 set_loop(newuse, use_loop);
1690 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1691
1692 // We need a Region to merge the exit from the peeled body and the
1693 // exit from the old loop body.
1694 RegionNode *r = new RegionNode(3);
1695 // Map the old use to the new merge point
1696 old_new.map( use->_idx, r );
1697 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1698 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1699
1700 // The original user of 'use' uses 'r' instead.
1701 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1702 Node* useuse = use->last_out(l);
1703 _igvn.rehash_node_delayed(useuse);
1704 uint uses_found = 0;
1705 if( useuse->in(0) == use ) {
1706 useuse->set_req(0, r);
1707 uses_found++;
1708 if( useuse->is_CFG() ) {
1709 assert( dom_depth(useuse) > dd_r, "" );
1710 set_idom(useuse, r, dom_depth(useuse));
1711 }
1712 }
1713 for( uint k = 1; k < useuse->req(); k++ ) {
1714 if( useuse->in(k) == use ) {
1715 useuse->set_req(k, r);
1716 uses_found++;
1717 }
1718 }
1719 l -= uses_found; // we deleted 1 or more copies of this edge
1720 }
1721
1722 // Now finish up 'r'
1723 r->set_req( 1, newuse );
1724 r->set_req( 2, use );
1725 _igvn.register_new_node_with_optimizer(r);
1726 set_loop(r, use_loop);
1727 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1728 } // End of if a loop-exit test
1729 }
1730 }
1731
1732 // Step 4: If loop-invariant use is not control, it must be dominated by a
1733 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1734 // there if needed. Make a Phi there merging old and new used values.
1735 Node_List *split_if_set = NULL;
1736 Node_List *split_bool_set = NULL;
1737 Node_List *split_cex_set = NULL;
1738 for( i = 0; i < loop->_body.size(); i++ ) {
1739 Node* old = loop->_body.at(i);
1740 Node* nnn = old_new[old->_idx];
1741 // Copy uses to a worklist, so I can munge the def-use info
1742 // with impunity.
1743 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1744 worklist.push(old->fast_out(j));
1745
1746 while( worklist.size() ) {
1747 Node *use = worklist.pop();
1748 if (!has_node(use)) continue; // Ignore dead nodes
1749 if (use->in(0) == C->top()) continue;
1750 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1751 // Check for data-use outside of loop - at least one of OLD or USE
1752 // must not be a CFG node.
1753 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1754
1755 // If the Data use is an IF, that means we have an IF outside of the
1756 // loop that is switching on a condition that is set inside of the
1757 // loop. Happens if people set a loop-exit flag; then test the flag
1758 // in the loop to break the loop, then test is again outside of the
1759 // loop to determine which way the loop exited.
1760 // Loop predicate If node connects to Bool node through Opaque1 node.
1761 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1762 // Since this code is highly unlikely, we lazily build the worklist
1763 // of such Nodes to go split.
1764 if( !split_if_set )
1765 split_if_set = new Node_List(area);
1766 split_if_set->push(use);
1767 }
1768 if( use->is_Bool() ) {
1769 if( !split_bool_set )
1770 split_bool_set = new Node_List(area);
1771 split_bool_set->push(use);
1772 }
1773 if( use->Opcode() == Op_CreateEx ) {
1774 if( !split_cex_set )
1775 split_cex_set = new Node_List(area);
1776 split_cex_set->push(use);
1777 }
1778
1779
1780 // Get "block" use is in
1781 uint idx = 0;
1782 while( use->in(idx) != old ) idx++;
1783 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1784 assert( !loop->is_member( get_loop( prev ) ), "" );
1785 Node *cfg = prev->_idx >= new_counter
1786 ? prev->in(2)
1787 : idom(prev);
1788 if( use->is_Phi() ) // Phi use is in prior block
1789 cfg = prev->in(idx); // NOT in block of Phi itself
1790 if (cfg->is_top()) { // Use is dead?
1791 _igvn.replace_input_of(use, idx, C->top());
1792 continue;
1793 }
1794
1795 while( !loop->is_member( get_loop( cfg ) ) ) {
1796 prev = cfg;
1797 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1798 }
1799 // If the use occurs after merging several exits from the loop, then
1800 // old value must have dominated all those exits. Since the same old
1801 // value was used on all those exits we did not need a Phi at this
1802 // merge point. NOW we do need a Phi here. Each loop exit value
1803 // is now merged with the peeled body exit; each exit gets its own
1804 // private Phi and those Phis need to be merged here.
1805 Node *phi;
1806 if( prev->is_Region() ) {
1807 if( idx == 0 ) { // Updating control edge?
1808 phi = prev; // Just use existing control
1809 } else { // Else need a new Phi
1810 phi = PhiNode::make( prev, old );
1811 // Now recursively fix up the new uses of old!
1812 for( uint i = 1; i < prev->req(); i++ ) {
1813 worklist.push(phi); // Onto worklist once for each 'old' input
1814 }
1815 }
1816 } else {
1817 // Get new RegionNode merging old and new loop exits
1818 prev = old_new[prev->_idx];
1819 assert( prev, "just made this in step 7" );
1820 if( idx == 0 ) { // Updating control edge?
1821 phi = prev; // Just use existing control
1822 } else { // Else need a new Phi
1823 // Make a new Phi merging data values properly
1824 phi = PhiNode::make( prev, old );
1825 phi->set_req( 1, nnn );
1826 }
1827 }
1828 // If inserting a new Phi, check for prior hits
1829 if( idx != 0 ) {
1830 Node *hit = _igvn.hash_find_insert(phi);
1831 if( hit == NULL ) {
1832 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1833 } else { // or
1834 // Remove the new phi from the graph and use the hit
1835 _igvn.remove_dead_node(phi);
1836 phi = hit; // Use existing phi
1837 }
1838 set_ctrl(phi, prev);
1839 }
1840 // Make 'use' use the Phi instead of the old loop body exit value
1841 _igvn.replace_input_of(use, idx, phi);
1842 if( use->_idx >= new_counter ) { // If updating new phis
1843 // Not needed for correctness, but prevents a weak assert
1844 // in AddPNode from tripping (when we end up with different
1845 // base & derived Phis that will become the same after
1846 // IGVN does CSE).
1847 Node *hit = _igvn.hash_find_insert(use);
1848 if( hit ) // Go ahead and re-hash for hits.
1849 _igvn.replace_node( use, hit );
1850 }
1851
1852 // If 'use' was in the loop-exit block, it now needs to be sunk
1853 // below the post-loop merge point.
1854 sink_use( use, prev );
1855 }
1856 }
1857 }
1858
1859 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1860 // the loop uses a condition set in the loop. The original IF probably
1861 // takes control from one or more OLD Regions (which in turn get from NEW
1862 // Regions). In any case, there will be a set of Phis for each merge point
1863 // from the IF up to where the original BOOL def exists the loop.
1864 if( split_if_set ) {
1865 while( split_if_set->size() ) {
1866 Node *iff = split_if_set->pop();
1867 if( iff->in(1)->is_Phi() ) {
1868 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1869 _igvn.replace_input_of(iff, 1, b);
1870 }
1871 }
1872 }
1873 if( split_bool_set ) {
1874 while( split_bool_set->size() ) {
1875 Node *b = split_bool_set->pop();
1876 Node *phi = b->in(1);
1877 assert( phi->is_Phi(), "" );
1878 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1879 _igvn.replace_input_of(b, 1, cmp);
1880 }
1881 }
1882 if( split_cex_set ) {
1883 while( split_cex_set->size() ) {
1884 Node *b = split_cex_set->pop();
1885 assert( b->in(0)->is_Region(), "" );
1886 assert( b->in(1)->is_Phi(), "" );
1887 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1888 split_up( b, b->in(0), NULL );
1889 }
1890 }
1891
1892 }
1893
1894
1895 //---------------------- stride_of_possible_iv -------------------------------------
1896 // Looks for an iff/bool/comp with one operand of the compare
1897 // being a cycle involving an add and a phi,
1898 // with an optional truncation (left-shift followed by a right-shift)
1899 // of the add. Returns zero if not an iv.
1900 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1901 Node* trunc1 = NULL;
1902 Node* trunc2 = NULL;
1903 const TypeInt* ttype = NULL;
1904 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1905 return 0;
1906 }
1907 BoolNode* bl = iff->in(1)->as_Bool();
1908 Node* cmp = bl->in(1);
1909 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1910 return 0;
1911 }
1912 // Must have an invariant operand
1913 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1914 return 0;
1915 }
1916 Node* add2 = NULL;
1917 Node* cmp1 = cmp->in(1);
1918 if (cmp1->is_Phi()) {
1919 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1920 Node* phi = cmp1;
1921 for (uint i = 1; i < phi->req(); i++) {
1922 Node* in = phi->in(i);
1923 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1924 &trunc1, &trunc2, &ttype);
1925 if (add && add->in(1) == phi) {
1926 add2 = add->in(2);
1927 break;
1928 }
1929 }
1930 } else {
1931 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1932 Node* addtrunc = cmp1;
1933 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1934 &trunc1, &trunc2, &ttype);
1935 if (add && add->in(1)->is_Phi()) {
1936 Node* phi = add->in(1);
1937 for (uint i = 1; i < phi->req(); i++) {
1938 if (phi->in(i) == addtrunc) {
1939 add2 = add->in(2);
1940 break;
1941 }
1942 }
1943 }
1944 }
1945 if (add2 != NULL) {
1946 const TypeInt* add2t = _igvn.type(add2)->is_int();
1947 if (add2t->is_con()) {
1948 return add2t->get_con();
1949 }
1950 }
1951 return 0;
1952 }
1953
1954
1955 //---------------------- stay_in_loop -------------------------------------
1956 // Return the (unique) control output node that's in the loop (if it exists.)
1957 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1958 Node* unique = NULL;
1959 if (!n) return NULL;
1960 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1961 Node* use = n->fast_out(i);
1962 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1963 if (unique != NULL) {
1964 return NULL;
1965 }
1966 unique = use;
1967 }
1968 }
1969 return unique;
1970 }
1971
1972 //------------------------------ register_node -------------------------------------
1973 // Utility to register node "n" with PhaseIdealLoop
1974 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1975 _igvn.register_new_node_with_optimizer(n);
1976 loop->_body.push(n);
1977 if (n->is_CFG()) {
1978 set_loop(n, loop);
1979 set_idom(n, pred, ddepth);
1980 } else {
1981 set_ctrl(n, pred);
1982 }
1983 }
1984
1985 //------------------------------ proj_clone -------------------------------------
1986 // Utility to create an if-projection
1987 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1988 ProjNode* c = p->clone()->as_Proj();
1989 c->set_req(0, iff);
1990 return c;
1991 }
1992
1993 //------------------------------ short_circuit_if -------------------------------------
1994 // Force the iff control output to be the live_proj
1995 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1996 guarantee(live_proj != NULL, "null projection");
1997 int proj_con = live_proj->_con;
1998 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1999 Node *con = _igvn.intcon(proj_con);
2000 set_ctrl(con, C->root());
2001 if (iff) {
2002 iff->set_req(1, con);
2003 }
2004 return con;
2005 }
2006
2007 //------------------------------ insert_if_before_proj -------------------------------------
2008 // Insert a new if before an if projection (* - new node)
2009 //
2010 // before
2011 // if(test)
2012 // / \
2013 // v v
2014 // other-proj proj (arg)
2015 //
2016 // after
2017 // if(test)
2018 // / \
2019 // / v
2020 // | * proj-clone
2021 // v |
2022 // other-proj v
2023 // * new_if(relop(cmp[IU](left,right)))
2024 // / \
2025 // v v
2026 // * new-proj proj
2027 // (returned)
2028 //
2029 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2030 IfNode* iff = proj->in(0)->as_If();
2031 IdealLoopTree *loop = get_loop(proj);
2032 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2033 int ddepth = dom_depth(proj);
2034
2035 _igvn.rehash_node_delayed(iff);
2036 _igvn.rehash_node_delayed(proj);
2037
2038 proj->set_req(0, NULL); // temporary disconnect
2039 ProjNode* proj2 = proj_clone(proj, iff);
2040 register_node(proj2, loop, iff, ddepth);
2041
2042 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2043 register_node(cmp, loop, proj2, ddepth);
2044
2045 BoolNode* bol = new BoolNode(cmp, relop);
2046 register_node(bol, loop, proj2, ddepth);
2047
2048 int opcode = iff->Opcode();
2049 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2050 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2051 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2052 register_node(new_if, loop, proj2, ddepth);
2053
2054 proj->set_req(0, new_if); // reattach
2055 set_idom(proj, new_if, ddepth);
2056
2057 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2058 guarantee(new_exit != NULL, "null exit node");
2059 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2060
2061 return new_exit;
2062 }
2063
2064 //------------------------------ insert_region_before_proj -------------------------------------
2065 // Insert a region before an if projection (* - new node)
2066 //
2067 // before
2068 // if(test)
2069 // / |
2070 // v |
2071 // proj v
2072 // other-proj
2073 //
2074 // after
2075 // if(test)
2076 // / |
2077 // v |
2078 // * proj-clone v
2079 // | other-proj
2080 // v
2081 // * new-region
2082 // |
2083 // v
2084 // * dum_if
2085 // / \
2086 // v \
2087 // * dum-proj v
2088 // proj
2089 //
2090 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2091 IfNode* iff = proj->in(0)->as_If();
2092 IdealLoopTree *loop = get_loop(proj);
2093 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2094 int ddepth = dom_depth(proj);
2095
2096 _igvn.rehash_node_delayed(iff);
2097 _igvn.rehash_node_delayed(proj);
2098
2099 proj->set_req(0, NULL); // temporary disconnect
2100 ProjNode* proj2 = proj_clone(proj, iff);
2101 register_node(proj2, loop, iff, ddepth);
2102
2103 RegionNode* reg = new RegionNode(2);
2104 reg->set_req(1, proj2);
2105 register_node(reg, loop, iff, ddepth);
2106
2107 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2108 register_node(dum_if, loop, reg, ddepth);
2109
2110 proj->set_req(0, dum_if); // reattach
2111 set_idom(proj, dum_if, ddepth);
2112
2113 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2114 register_node(dum_proj, loop, dum_if, ddepth);
2115
2116 return reg;
2117 }
2118
2119 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2120 // Clone a signed compare loop exit from an unsigned compare and
2121 // insert it before the unsigned cmp on the stay-in-loop path.
2122 // All new nodes inserted in the dominator tree between the original
2123 // if and it's projections. The original if test is replaced with
2124 // a constant to force the stay-in-loop path.
2125 //
2126 // This is done to make sure that the original if and it's projections
2127 // still dominate the same set of control nodes, that the ctrl() relation
2128 // from data nodes to them is preserved, and that their loop nesting is
2129 // preserved.
2130 //
2131 // before
2132 // if(i <u limit) unsigned compare loop exit
2133 // / |
2134 // v v
2135 // exit-proj stay-in-loop-proj
2136 //
2137 // after
2138 // if(stay-in-loop-const) original if
2139 // / |
2140 // / v
2141 // / if(i < limit) new signed test
2142 // / / |
2143 // / / v
2144 // / / if(i <u limit) new cloned unsigned test
2145 // / / / |
2146 // v v v |
2147 // region |
2148 // | |
2149 // dum-if |
2150 // / | |
2151 // ether | |
2152 // v v
2153 // exit-proj stay-in-loop-proj
2154 //
2155 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2156 const bool Signed = true;
2157 const bool Unsigned = false;
2158
2159 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2160 if (bol->_test._test != BoolTest::lt) return NULL;
2161 CmpNode* cmpu = bol->in(1)->as_Cmp();
2162 if (cmpu->Opcode() != Op_CmpU) return NULL;
2163 int stride = stride_of_possible_iv(if_cmpu);
2164 if (stride == 0) return NULL;
2165
2166 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2167 guarantee(lp_proj != NULL, "null loop node");
2168
2169 ProjNode* lp_continue = lp_proj->as_Proj();
2170 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2171
2172 Node* limit = NULL;
2173 if (stride > 0) {
2174 limit = cmpu->in(2);
2175 } else {
2176 limit = _igvn.makecon(TypeInt::ZERO);
2177 set_ctrl(limit, C->root());
2178 }
2179 // Create a new region on the exit path
2180 RegionNode* reg = insert_region_before_proj(lp_exit);
2181 guarantee(reg != NULL, "null region node");
2182
2183 // Clone the if-cmpu-true-false using a signed compare
2184 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2185 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2186 reg->add_req(cmpi_exit);
2187
2188 // Clone the if-cmpu-true-false
2189 BoolTest::mask rel_u = bol->_test._test;
2190 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2191 reg->add_req(cmpu_exit);
2192
2193 // Force original if to stay in loop.
2194 short_circuit_if(if_cmpu, lp_continue);
2195
2196 return cmpi_exit->in(0)->as_If();
2197 }
2198
2199 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2200 // Remove a previously inserted signed compare loop exit.
2201 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2202 Node* lp_proj = stay_in_loop(if_cmp, loop);
2203 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2204 stay_in_loop(lp_proj, loop)->is_If() &&
2205 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2206 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2207 set_ctrl(con, C->root());
2208 if_cmp->set_req(1, con);
2209 }
2210
2211 //------------------------------ scheduled_nodelist -------------------------------------
2212 // Create a post order schedule of nodes that are in the
2213 // "member" set. The list is returned in "sched".
2214 // The first node in "sched" is the loop head, followed by
2215 // nodes which have no inputs in the "member" set, and then
2216 // followed by the nodes that have an immediate input dependence
2217 // on a node in "sched".
2218 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2219
2220 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2221 Arena *a = Thread::current()->resource_area();
2222 VectorSet visited(a);
2223 Node_Stack nstack(a, loop->_body.size());
2224
2225 Node* n = loop->_head; // top of stack is cached in "n"
2226 uint idx = 0;
2227 visited.set(n->_idx);
2228
2229 // Initially push all with no inputs from within member set
2230 for(uint i = 0; i < loop->_body.size(); i++ ) {
2231 Node *elt = loop->_body.at(i);
2232 if (member.test(elt->_idx)) {
2233 bool found = false;
2234 for (uint j = 0; j < elt->req(); j++) {
2235 Node* def = elt->in(j);
2236 if (def && member.test(def->_idx) && def != elt) {
2237 found = true;
2238 break;
2239 }
2240 }
2241 if (!found && elt != loop->_head) {
2242 nstack.push(n, idx);
2243 n = elt;
2244 assert(!visited.test(n->_idx), "not seen yet");
2245 visited.set(n->_idx);
2246 }
2247 }
2248 }
2249
2250 // traverse out's that are in the member set
2251 while (true) {
2252 if (idx < n->outcnt()) {
2253 Node* use = n->raw_out(idx);
2254 idx++;
2255 if (!visited.test_set(use->_idx)) {
2256 if (member.test(use->_idx)) {
2257 nstack.push(n, idx);
2258 n = use;
2259 idx = 0;
2260 }
2261 }
2262 } else {
2263 // All outputs processed
2264 sched.push(n);
2265 if (nstack.is_empty()) break;
2266 n = nstack.node();
2267 idx = nstack.index();
2268 nstack.pop();
2269 }
2270 }
2271 }
2272
2273
2274 //------------------------------ has_use_in_set -------------------------------------
2275 // Has a use in the vector set
2276 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2277 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2278 Node* use = n->fast_out(j);
2279 if (vset.test(use->_idx)) {
2280 return true;
2281 }
2282 }
2283 return false;
2284 }
2285
2286
2287 //------------------------------ has_use_internal_to_set -------------------------------------
2288 // Has use internal to the vector set (ie. not in a phi at the loop head)
2289 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2290 Node* head = loop->_head;
2291 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2292 Node* use = n->fast_out(j);
2293 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2294 return true;
2295 }
2296 }
2297 return false;
2298 }
2299
2300
2301 //------------------------------ clone_for_use_outside_loop -------------------------------------
2302 // clone "n" for uses that are outside of loop
2303 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2304 int cloned = 0;
2305 assert(worklist.size() == 0, "should be empty");
2306 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2307 Node* use = n->fast_out(j);
2308 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2309 worklist.push(use);
2310 }
2311 }
2312 while( worklist.size() ) {
2313 Node *use = worklist.pop();
2314 if (!has_node(use) || use->in(0) == C->top()) continue;
2315 uint j;
2316 for (j = 0; j < use->req(); j++) {
2317 if (use->in(j) == n) break;
2318 }
2319 assert(j < use->req(), "must be there");
2320
2321 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2322 Node* n_clone = n->clone();
2323 _igvn.replace_input_of(use, j, n_clone);
2324 cloned++;
2325 Node* use_c;
2326 if (!use->is_Phi()) {
2327 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2328 } else {
2329 // Use in a phi is considered a use in the associated predecessor block
2330 use_c = use->in(0)->in(j);
2331 }
2332 set_ctrl(n_clone, use_c);
2333 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2334 get_loop(use_c)->_body.push(n_clone);
2335 _igvn.register_new_node_with_optimizer(n_clone);
2336 #if !defined(PRODUCT)
2337 if (TracePartialPeeling) {
2338 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2339 }
2340 #endif
2341 }
2342 return cloned;
2343 }
2344
2345
2346 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2347 // clone "n" for special uses that are in the not_peeled region.
2348 // If these def-uses occur in separate blocks, the code generator
2349 // marks the method as not compilable. For example, if a "BoolNode"
2350 // is in a different basic block than the "IfNode" that uses it, then
2351 // the compilation is aborted in the code generator.
2352 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2353 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2354 if (n->is_Phi() || n->is_Load()) {
2355 return;
2356 }
2357 assert(worklist.size() == 0, "should be empty");
2358 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2359 Node* use = n->fast_out(j);
2360 if ( not_peel.test(use->_idx) &&
2361 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2362 use->in(1) == n) {
2363 worklist.push(use);
2364 }
2365 }
2366 if (worklist.size() > 0) {
2367 // clone "n" and insert it between inputs of "n" and the use
2368 Node* n_clone = n->clone();
2369 loop->_body.push(n_clone);
2370 _igvn.register_new_node_with_optimizer(n_clone);
2371 set_ctrl(n_clone, get_ctrl(n));
2372 sink_list.push(n_clone);
2373 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2374 #if !defined(PRODUCT)
2375 if (TracePartialPeeling) {
2376 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2377 }
2378 #endif
2379 while( worklist.size() ) {
2380 Node *use = worklist.pop();
2381 _igvn.rehash_node_delayed(use);
2382 for (uint j = 1; j < use->req(); j++) {
2383 if (use->in(j) == n) {
2384 use->set_req(j, n_clone);
2385 }
2386 }
2387 }
2388 }
2389 }
2390
2391
2392 //------------------------------ insert_phi_for_loop -------------------------------------
2393 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2394 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2395 Node *phi = PhiNode::make(lp, back_edge_val);
2396 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2397 // Use existing phi if it already exists
2398 Node *hit = _igvn.hash_find_insert(phi);
2399 if( hit == NULL ) {
2400 _igvn.register_new_node_with_optimizer(phi);
2401 set_ctrl(phi, lp);
2402 } else {
2403 // Remove the new phi from the graph and use the hit
2404 _igvn.remove_dead_node(phi);
2405 phi = hit;
2406 }
2407 _igvn.replace_input_of(use, idx, phi);
2408 }
2409
2410 #ifdef ASSERT
2411 //------------------------------ is_valid_loop_partition -------------------------------------
2412 // Validate the loop partition sets: peel and not_peel
2413 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2414 VectorSet& not_peel ) {
2415 uint i;
2416 // Check that peel_list entries are in the peel set
2417 for (i = 0; i < peel_list.size(); i++) {
2418 if (!peel.test(peel_list.at(i)->_idx)) {
2419 return false;
2420 }
2421 }
2422 // Check at loop members are in one of peel set or not_peel set
2423 for (i = 0; i < loop->_body.size(); i++ ) {
2424 Node *def = loop->_body.at(i);
2425 uint di = def->_idx;
2426 // Check that peel set elements are in peel_list
2427 if (peel.test(di)) {
2428 if (not_peel.test(di)) {
2429 return false;
2430 }
2431 // Must be in peel_list also
2432 bool found = false;
2433 for (uint j = 0; j < peel_list.size(); j++) {
2434 if (peel_list.at(j)->_idx == di) {
2435 found = true;
2436 break;
2437 }
2438 }
2439 if (!found) {
2440 return false;
2441 }
2442 } else if (not_peel.test(di)) {
2443 if (peel.test(di)) {
2444 return false;
2445 }
2446 } else {
2447 return false;
2448 }
2449 }
2450 return true;
2451 }
2452
2453 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2454 // Ensure a use outside of loop is of the right form
2455 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2456 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2457 return (use->is_Phi() &&
2458 use_c->is_Region() && use_c->req() == 3 &&
2459 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2460 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2461 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2462 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2463 }
2464
2465 //------------------------------ is_valid_clone_loop_form -------------------------------------
2466 // Ensure that all uses outside of loop are of the right form
2467 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2468 uint orig_exit_idx, uint clone_exit_idx) {
2469 uint len = peel_list.size();
2470 for (uint i = 0; i < len; i++) {
2471 Node *def = peel_list.at(i);
2472
2473 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2474 Node *use = def->fast_out(j);
2475 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2476 if (!loop->is_member(get_loop(use_c))) {
2477 // use is not in the loop, check for correct structure
2478 if (use->in(0) == def) {
2479 // Okay
2480 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2481 return false;
2482 }
2483 }
2484 }
2485 }
2486 return true;
2487 }
2488 #endif
2489
2490 //------------------------------ partial_peel -------------------------------------
2491 // Partially peel (aka loop rotation) the top portion of a loop (called
2492 // the peel section below) by cloning it and placing one copy just before
2493 // the new loop head and the other copy at the bottom of the new loop.
2494 //
2495 // before after where it came from
2496 //
2497 // stmt1 stmt1
2498 // loop: stmt2 clone
2499 // stmt2 if condA goto exitA clone
2500 // if condA goto exitA new_loop: new
2501 // stmt3 stmt3 clone
2502 // if !condB goto loop if condB goto exitB clone
2503 // exitB: stmt2 orig
2504 // stmt4 if !condA goto new_loop orig
2505 // exitA: goto exitA
2506 // exitB:
2507 // stmt4
2508 // exitA:
2509 //
2510 // Step 1: find the cut point: an exit test on probable
2511 // induction variable.
2512 // Step 2: schedule (with cloning) operations in the peel
2513 // section that can be executed after the cut into
2514 // the section that is not peeled. This may need
2515 // to clone operations into exit blocks. For
2516 // instance, a reference to A[i] in the not-peel
2517 // section and a reference to B[i] in an exit block
2518 // may cause a left-shift of i by 2 to be placed
2519 // in the peel block. This step will clone the left
2520 // shift into the exit block and sink the left shift
2521 // from the peel to the not-peel section.
2522 // Step 3: clone the loop, retarget the control, and insert
2523 // phis for values that are live across the new loop
2524 // head. This is very dependent on the graph structure
2525 // from clone_loop. It creates region nodes for
2526 // exit control and associated phi nodes for values
2527 // flow out of the loop through that exit. The region
2528 // node is dominated by the clone's control projection.
2529 // So the clone's peel section is placed before the
2530 // new loop head, and the clone's not-peel section is
2531 // forms the top part of the new loop. The original
2532 // peel section forms the tail of the new loop.
2533 // Step 4: update the dominator tree and recompute the
2534 // dominator depth.
2535 //
2536 // orig
2537 //
2538 // stmt1
2539 // |
2540 // v
2541 // loop predicate
2542 // |
2543 // v
2544 // loop<----+
2545 // | |
2546 // stmt2 |
2547 // | |
2548 // v |
2549 // ifA |
2550 // / | |
2551 // v v |
2552 // false true ^ <-- last_peel
2553 // / | |
2554 // / ===|==cut |
2555 // / stmt3 | <-- first_not_peel
2556 // / | |
2557 // | v |
2558 // v ifB |
2559 // exitA: / \ |
2560 // / \ |
2561 // v v |
2562 // false true |
2563 // / \ |
2564 // / ----+
2565 // |
2566 // v
2567 // exitB:
2568 // stmt4
2569 //
2570 //
2571 // after clone loop
2572 //
2573 // stmt1
2574 // |
2575 // v
2576 // loop predicate
2577 // / \
2578 // clone / \ orig
2579 // / \
2580 // / \
2581 // v v
2582 // +---->loop loop<----+
2583 // | | | |
2584 // | stmt2 stmt2 |
2585 // | | | |
2586 // | v v |
2587 // | ifA ifA |
2588 // | | \ / | |
2589 // | v v v v |
2590 // ^ true false false true ^ <-- last_peel
2591 // | | ^ \ / | |
2592 // | cut==|== \ \ / ===|==cut |
2593 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2594 // | | dom | | | |
2595 // | v \ 1v v2 v |
2596 // | ifB regionA ifB |
2597 // | / \ | / \ |
2598 // | / \ v / \ |
2599 // | v v exitA: v v |
2600 // | true false false true |
2601 // | / ^ \ / \ |
2602 // +---- \ \ / ----+
2603 // dom \ /
2604 // \ 1v v2
2605 // regionB
2606 // |
2607 // v
2608 // exitB:
2609 // stmt4
2610 //
2611 //
2612 // after partial peel
2613 //
2614 // stmt1
2615 // |
2616 // v
2617 // loop predicate
2618 // /
2619 // clone / orig
2620 // / TOP
2621 // / \
2622 // v v
2623 // TOP->loop loop----+
2624 // | | |
2625 // stmt2 stmt2 |
2626 // | | |
2627 // v v |
2628 // ifA ifA |
2629 // | \ / | |
2630 // v v v v |
2631 // true false false true | <-- last_peel
2632 // | ^ \ / +------|---+
2633 // +->newloop \ \ / === ==cut | |
2634 // | stmt3 \ \ / TOP | |
2635 // | | dom | | stmt3 | | <-- first_not_peel
2636 // | v \ 1v v2 v | |
2637 // | ifB regionA ifB ^ v
2638 // | / \ | / \ | |
2639 // | / \ v / \ | |
2640 // | v v exitA: v v | |
2641 // | true false false true | |
2642 // | / ^ \ / \ | |
2643 // | | \ \ / v | |
2644 // | | dom \ / TOP | |
2645 // | | \ 1v v2 | |
2646 // ^ v regionB | |
2647 // | | | | |
2648 // | | v ^ v
2649 // | | exitB: | |
2650 // | | stmt4 | |
2651 // | +------------>-----------------+ |
2652 // | |
2653 // +-----------------<---------------------+
2654 //
2655 //
2656 // final graph
2657 //
2658 // stmt1
2659 // |
2660 // v
2661 // loop predicate
2662 // |
2663 // v
2664 // stmt2 clone
2665 // |
2666 // v
2667 // ........> ifA clone
2668 // : / |
2669 // dom / |
2670 // : v v
2671 // : false true
2672 // : | |
2673 // : | v
2674 // : | newloop<-----+
2675 // : | | |
2676 // : | stmt3 clone |
2677 // : | | |
2678 // : | v |
2679 // : | ifB |
2680 // : | / \ |
2681 // : | v v |
2682 // : | false true |
2683 // : | | | |
2684 // : | v stmt2 |
2685 // : | exitB: | |
2686 // : | stmt4 v |
2687 // : | ifA orig |
2688 // : | / \ |
2689 // : | / \ |
2690 // : | v v |
2691 // : | false true |
2692 // : | / \ |
2693 // : v v -----+
2694 // RegionA
2695 // |
2696 // v
2697 // exitA
2698 //
2699 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2700
2701 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2702 if (!loop->_head->is_Loop()) {
2703 return false; }
2704
2705 LoopNode *head = loop->_head->as_Loop();
2706
2707 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2708 return false;
2709 }
2710
2711 // Check for complex exit control
2712 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2713 Node *n = loop->_body.at(ii);
2714 int opc = n->Opcode();
2715 if (n->is_Call() ||
2716 opc == Op_Catch ||
2717 opc == Op_CatchProj ||
2718 opc == Op_Jump ||
2719 opc == Op_JumpProj) {
2720 #if !defined(PRODUCT)
2721 if (TracePartialPeeling) {
2722 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2723 }
2724 #endif
2725 return false;
2726 }
2727 }
2728
2729 int dd = dom_depth(head);
2730
2731 // Step 1: find cut point
2732
2733 // Walk up dominators to loop head looking for first loop exit
2734 // which is executed on every path thru loop.
2735 IfNode *peel_if = NULL;
2736 IfNode *peel_if_cmpu = NULL;
2737
2738 Node *iff = loop->tail();
2739 while( iff != head ) {
2740 if( iff->is_If() ) {
2741 Node *ctrl = get_ctrl(iff->in(1));
2742 if (ctrl->is_top()) return false; // Dead test on live IF.
2743 // If loop-varying exit-test, check for induction variable
2744 if( loop->is_member(get_loop(ctrl)) &&
2745 loop->is_loop_exit(iff) &&
2746 is_possible_iv_test(iff)) {
2747 Node* cmp = iff->in(1)->in(1);
2748 if (cmp->Opcode() == Op_CmpI) {
2749 peel_if = iff->as_If();
2750 } else {
2751 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2752 peel_if_cmpu = iff->as_If();
2753 }
2754 }
2755 }
2756 iff = idom(iff);
2757 }
2758 // Prefer signed compare over unsigned compare.
2759 IfNode* new_peel_if = NULL;
2760 if (peel_if == NULL) {
2761 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2762 return false; // No peel point found
2763 }
2764 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2765 if (new_peel_if == NULL) {
2766 return false; // No peel point found
2767 }
2768 peel_if = new_peel_if;
2769 }
2770 Node* last_peel = stay_in_loop(peel_if, loop);
2771 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2772 if (first_not_peeled == NULL || first_not_peeled == head) {
2773 return false;
2774 }
2775
2776 #if !defined(PRODUCT)
2777 if (TraceLoopOpts) {
2778 tty->print("PartialPeel ");
2779 loop->dump_head();
2780 }
2781
2782 if (TracePartialPeeling) {
2783 tty->print_cr("before partial peel one iteration");
2784 Node_List wl;
2785 Node* t = head->in(2);
2786 while (true) {
2787 wl.push(t);
2788 if (t == head) break;
2789 t = idom(t);
2790 }
2791 while (wl.size() > 0) {
2792 Node* tt = wl.pop();
2793 tt->dump();
2794 if (tt == last_peel) tty->print_cr("-- cut --");
2795 }
2796 }
2797 #endif
2798 ResourceArea *area = Thread::current()->resource_area();
2799 VectorSet peel(area);
2800 VectorSet not_peel(area);
2801 Node_List peel_list(area);
2802 Node_List worklist(area);
2803 Node_List sink_list(area);
2804
2805 // Set of cfg nodes to peel are those that are executable from
2806 // the head through last_peel.
2807 assert(worklist.size() == 0, "should be empty");
2808 worklist.push(head);
2809 peel.set(head->_idx);
2810 while (worklist.size() > 0) {
2811 Node *n = worklist.pop();
2812 if (n != last_peel) {
2813 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2814 Node* use = n->fast_out(j);
2815 if (use->is_CFG() &&
2816 loop->is_member(get_loop(use)) &&
2817 !peel.test_set(use->_idx)) {
2818 worklist.push(use);
2819 }
2820 }
2821 }
2822 }
2823
2824 // Set of non-cfg nodes to peel are those that are control
2825 // dependent on the cfg nodes.
2826 uint i;
2827 for(i = 0; i < loop->_body.size(); i++ ) {
2828 Node *n = loop->_body.at(i);
2829 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2830 if (peel.test(n_c->_idx)) {
2831 peel.set(n->_idx);
2832 } else {
2833 not_peel.set(n->_idx);
2834 }
2835 }
2836
2837 // Step 2: move operations from the peeled section down into the
2838 // not-peeled section
2839
2840 // Get a post order schedule of nodes in the peel region
2841 // Result in right-most operand.
2842 scheduled_nodelist(loop, peel, peel_list );
2843
2844 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2845
2846 // For future check for too many new phis
2847 uint old_phi_cnt = 0;
2848 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2849 Node* use = head->fast_out(j);
2850 if (use->is_Phi()) old_phi_cnt++;
2851 }
2852
2853 #if !defined(PRODUCT)
2854 if (TracePartialPeeling) {
2855 tty->print_cr("\npeeled list");
2856 }
2857 #endif
2858
2859 // Evacuate nodes in peel region into the not_peeled region if possible
2860 uint new_phi_cnt = 0;
2861 uint cloned_for_outside_use = 0;
2862 for (i = 0; i < peel_list.size();) {
2863 Node* n = peel_list.at(i);
2864 #if !defined(PRODUCT)
2865 if (TracePartialPeeling) n->dump();
2866 #endif
2867 bool incr = true;
2868 if ( !n->is_CFG() ) {
2869
2870 if ( has_use_in_set(n, not_peel) ) {
2871
2872 // If not used internal to the peeled region,
2873 // move "n" from peeled to not_peeled region.
2874
2875 if ( !has_use_internal_to_set(n, peel, loop) ) {
2876
2877 // if not pinned and not a load (which maybe anti-dependent on a store)
2878 // and not a CMove (Matcher expects only bool->cmove).
2879 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2880 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2881 sink_list.push(n);
2882 peel >>= n->_idx; // delete n from peel set.
2883 not_peel <<= n->_idx; // add n to not_peel set.
2884 peel_list.remove(i);
2885 incr = false;
2886 #if !defined(PRODUCT)
2887 if (TracePartialPeeling) {
2888 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2889 n->_idx, get_ctrl(n)->_idx);
2890 }
2891 #endif
2892 }
2893 } else {
2894 // Otherwise check for special def-use cases that span
2895 // the peel/not_peel boundary such as bool->if
2896 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2897 new_phi_cnt++;
2898 }
2899 }
2900 }
2901 if (incr) i++;
2902 }
2903
2904 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2905 #if !defined(PRODUCT)
2906 if (TracePartialPeeling) {
2907 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2908 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2909 }
2910 #endif
2911 if (new_peel_if != NULL) {
2912 remove_cmpi_loop_exit(new_peel_if, loop);
2913 }
2914 // Inhibit more partial peeling on this loop
2915 assert(!head->is_partial_peel_loop(), "not partial peeled");
2916 head->mark_partial_peel_failed();
2917 if (cloned_for_outside_use > 0) {
2918 // Terminate this round of loop opts because
2919 // the graph outside this loop was changed.
2920 C->set_major_progress();
2921 return true;
2922 }
2923 return false;
2924 }
2925
2926 // Step 3: clone loop, retarget control, and insert new phis
2927
2928 // Create new loop head for new phis and to hang
2929 // the nodes being moved (sinked) from the peel region.
2930 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2931 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2932 _igvn.register_new_node_with_optimizer(new_head);
2933 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2934 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2935 set_loop(new_head, loop);
2936 loop->_body.push(new_head);
2937 not_peel.set(new_head->_idx);
2938 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2939 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2940
2941 while (sink_list.size() > 0) {
2942 Node* n = sink_list.pop();
2943 set_ctrl(n, new_head);
2944 }
2945
2946 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2947
2948 clone_loop( loop, old_new, dd );
2949
2950 const uint clone_exit_idx = 1;
2951 const uint orig_exit_idx = 2;
2952 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2953
2954 Node* head_clone = old_new[head->_idx];
2955 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2956 Node* orig_tail_clone = head_clone->in(2);
2957
2958 // Add phi if "def" node is in peel set and "use" is not
2959
2960 for(i = 0; i < peel_list.size(); i++ ) {
2961 Node *def = peel_list.at(i);
2962 if (!def->is_CFG()) {
2963 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2964 Node *use = def->fast_out(j);
2965 if (has_node(use) && use->in(0) != C->top() &&
2966 (!peel.test(use->_idx) ||
2967 (use->is_Phi() && use->in(0) == head)) ) {
2968 worklist.push(use);
2969 }
2970 }
2971 while( worklist.size() ) {
2972 Node *use = worklist.pop();
2973 for (uint j = 1; j < use->req(); j++) {
2974 Node* n = use->in(j);
2975 if (n == def) {
2976
2977 // "def" is in peel set, "use" is not in peel set
2978 // or "use" is in the entry boundary (a phi) of the peel set
2979
2980 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2981
2982 if ( loop->is_member(get_loop( use_c )) ) {
2983 // use is in loop
2984 if (old_new[use->_idx] != NULL) { // null for dead code
2985 Node* use_clone = old_new[use->_idx];
2986 _igvn.replace_input_of(use, j, C->top());
2987 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2988 }
2989 } else {
2990 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2991 // use is not in the loop, check if the live range includes the cut
2992 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2993 if (not_peel.test(lp_if->_idx)) {
2994 assert(j == orig_exit_idx, "use from original loop");
2995 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2996 }
2997 }
2998 }
2999 }
3000 }
3001 }
3002 }
3003
3004 // Step 3b: retarget control
3005
3006 // Redirect control to the new loop head if a cloned node in
3007 // the not_peeled region has control that points into the peeled region.
3008 // This necessary because the cloned peeled region will be outside
3009 // the loop.
3010 // from to
3011 // cloned-peeled <---+
3012 // new_head_clone: | <--+
3013 // cloned-not_peeled in(0) in(0)
3014 // orig-peeled
3015
3016 for(i = 0; i < loop->_body.size(); i++ ) {
3017 Node *n = loop->_body.at(i);
3018 if (!n->is_CFG() && n->in(0) != NULL &&
3019 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3020 Node* n_clone = old_new[n->_idx];
3021 _igvn.replace_input_of(n_clone, 0, new_head_clone);
3022 }
3023 }
3024
3025 // Backedge of the surviving new_head (the clone) is original last_peel
3026 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3027
3028 // Cut first node in original not_peel set
3029 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
3030 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
3031 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
3032
3033 // Copy head_clone back-branch info to original head
3034 // and remove original head's loop entry and
3035 // clone head's back-branch
3036 _igvn.rehash_node_delayed(head); // Multiple edge updates
3037 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
3038 head->set_req(LoopNode::LoopBackControl, C->top());
3039 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3040
3041 // Similarly modify the phis
3042 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3043 Node* use = head->fast_out(k);
3044 if (use->is_Phi() && use->outcnt() > 0) {
3045 Node* use_clone = old_new[use->_idx];
3046 _igvn.rehash_node_delayed(use); // Multiple edge updates
3047 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
3048 use->set_req(LoopNode::LoopBackControl, C->top());
3049 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3050 }
3051 }
3052
3053 // Step 4: update dominator tree and dominator depth
3054
3055 set_idom(head, orig_tail_clone, dd);
3056 recompute_dom_depth();
3057
3058 // Inhibit more partial peeling on this loop
3059 new_head_clone->set_partial_peel_loop();
3060 C->set_major_progress();
3061 loop->record_for_igvn();
3062
3063 #if !defined(PRODUCT)
3064 if (TracePartialPeeling) {
3065 tty->print_cr("\nafter partial peel one iteration");
3066 Node_List wl(area);
3067 Node* t = last_peel;
3068 while (true) {
3069 wl.push(t);
3070 if (t == head_clone) break;
3071 t = idom(t);
3072 }
3073 while (wl.size() > 0) {
3074 Node* tt = wl.pop();
3075 if (tt == head) tty->print_cr("orig head");
3076 else if (tt == new_head_clone) tty->print_cr("new head");
3077 else if (tt == head_clone) tty->print_cr("clone head");
3078 tt->dump();
3079 }
3080 }
3081 #endif
3082 return true;
3083 }
3084
3085 //------------------------------reorg_offsets----------------------------------
3086 // Reorganize offset computations to lower register pressure. Mostly
3087 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3088 // then alive with the post-incremented trip counter forcing an extra
3089 // register move)
3090 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3091 // Perform it only for canonical counted loops.
3092 // Loop's shape could be messed up by iteration_split_impl.
3093 if (!loop->_head->is_CountedLoop())
3094 return;
3095 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3096 return;
3097
3098 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3099 CountedLoopEndNode *cle = cl->loopexit();
3100 Node *exit = cle->proj_out(false);
3101 Node *phi = cl->phi();
3102
3103 // Check for the special case of folks using the pre-incremented
3104 // trip-counter on the fall-out path (forces the pre-incremented
3105 // and post-incremented trip counter to be live at the same time).
3106 // Fix this by adjusting to use the post-increment trip counter.
3107
3108 bool progress = true;
3109 while (progress) {
3110 progress = false;
3111 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3112 Node* use = phi->fast_out(i); // User of trip-counter
3113 if (!has_ctrl(use)) continue;
3114 Node *u_ctrl = get_ctrl(use);
3115 if (use->is_Phi()) {
3116 u_ctrl = NULL;
3117 for (uint j = 1; j < use->req(); j++)
3118 if (use->in(j) == phi)
3119 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3120 }
3121 IdealLoopTree *u_loop = get_loop(u_ctrl);
3122 // Look for loop-invariant use
3123 if (u_loop == loop) continue;
3124 if (loop->is_member(u_loop)) continue;
3125 // Check that use is live out the bottom. Assuming the trip-counter
3126 // update is right at the bottom, uses of of the loop middle are ok.
3127 if (dom_lca(exit, u_ctrl) != exit) continue;
3128 // Hit! Refactor use to use the post-incremented tripcounter.
3129 // Compute a post-increment tripcounter.
3130 Node *opaq = new Opaque2Node( C, cle->incr() );
3131 register_new_node(opaq, exit);
3132 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3133 set_ctrl(neg_stride, C->root());
3134 Node *post = new AddINode( opaq, neg_stride);
3135 register_new_node(post, exit);
3136 _igvn.rehash_node_delayed(use);
3137 for (uint j = 1; j < use->req(); j++) {
3138 if (use->in(j) == phi)
3139 use->set_req(j, post);
3140 }
3141 // Since DU info changed, rerun loop
3142 progress = true;
3143 break;
3144 }
3145 }
3146
3147 }