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