1 /*
2 * Copyright 1999-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
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 = new (C,region->req()) PhiNode(region, type);
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.hash_delete( n );
358 _igvn.subsume_node( n, var_add );
359 return var_add;
360 }
361
362 // Replace (I+V) with (V+I)
363 if( n_op == Op_AddI ||
364 n_op == Op_AddL ||
365 n_op == Op_AddF ||
366 n_op == Op_AddD ||
367 n_op == Op_MulI ||
368 n_op == Op_MulL ||
369 n_op == Op_MulF ||
370 n_op == Op_MulD ) {
371 if( n2_loop == n_loop ) {
372 assert( n1_loop != n_loop, "" );
373 n->swap_edges(1, 2);
374 }
375 }
376
377 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
378 // but not if I2 is a constant.
379 if( n_op == Op_AddP ) {
380 if( n2_loop == n_loop && n3_loop != n_loop ) {
381 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
382 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
383 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
384 IdealLoopTree *n22loop = get_loop( n22_ctrl );
385 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
386 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
387 n23_loop == n_loop ) {
388 Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
389 // Stuff new AddP in the loop preheader
390 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
391 Node *add2 = new (C, 4) AddPNode( n->in(1), add1, n->in(2)->in(3) );
392 register_new_node( add2, n_ctrl );
393 _igvn.hash_delete( n );
394 _igvn.subsume_node( n, add2 );
395 return add2;
396 }
397 }
398 }
399
400 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
401 if( n2_loop != n_loop && n3_loop == n_loop ) {
402 if( n->in(3)->Opcode() == Op_AddI ) {
403 Node *V = n->in(3)->in(1);
404 Node *I = n->in(3)->in(2);
405 if( is_member(n_loop,get_ctrl(V)) ) {
406 } else {
407 Node *tmp = V; V = I; I = tmp;
408 }
409 if( !is_member(n_loop,get_ctrl(I)) ) {
410 Node *add1 = new (C, 4) AddPNode( n->in(1), n->in(2), I );
411 // Stuff new AddP in the loop preheader
412 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
413 Node *add2 = new (C, 4) AddPNode( n->in(1), add1, V );
414 register_new_node( add2, n_ctrl );
415 _igvn.hash_delete( n );
416 _igvn.subsume_node( n, add2 );
417 return add2;
418 }
419 }
420 }
421 }
422
423 return NULL;
424 }
425
426 //------------------------------conditional_move-------------------------------
427 // Attempt to replace a Phi with a conditional move. We have some pretty
428 // strict profitability requirements. All Phis at the merge point must
429 // be converted, so we can remove the control flow. We need to limit the
430 // number of c-moves to a small handful. All code that was in the side-arms
431 // of the CFG diamond is now speculatively executed. This code has to be
432 // "cheap enough". We are pretty much limited to CFG diamonds that merge
433 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
434 Node *PhaseIdealLoop::conditional_move( Node *region ) {
435
436 assert( region->is_Region(), "sanity check" );
437 if( region->req() != 3 ) return NULL;
438
439 // Check for CFG diamond
440 Node *lp = region->in(1);
441 Node *rp = region->in(2);
442 if( !lp || !rp ) return NULL;
443 Node *lp_c = lp->in(0);
444 if( lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If() ) return NULL;
445 IfNode *iff = lp_c->as_If();
446
447 // Check for highly predictable branch. No point in CMOV'ing if
448 // we are going to predict accurately all the time.
449 // %%% This hides patterns produced by utility methods like Math.min.
450 if( iff->_prob < PROB_UNLIKELY_MAG(3) ||
451 iff->_prob > PROB_LIKELY_MAG(3) )
452 return NULL;
453
454 // Check for ops pinned in an arm of the diamond.
455 // Can't remove the control flow in this case
456 if( lp->outcnt() > 1 ) return NULL;
457 if( rp->outcnt() > 1 ) return NULL;
458
459 // Check profitability
460 int cost = 0;
461 int phis = 0;
462 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
463 Node *out = region->fast_out(i);
464 if( !out->is_Phi() ) continue; // Ignore other control edges, etc
465 phis++;
466 PhiNode* phi = out->as_Phi();
467 switch (phi->type()->basic_type()) {
468 case T_LONG:
469 cost++; // Probably encodes as 2 CMOV's
470 case T_INT: // These all CMOV fine
471 case T_FLOAT:
472 case T_DOUBLE:
473 case T_ADDRESS: // (RawPtr)
474 cost++;
475 break;
476 case T_NARROWOOP: // Fall through
477 case T_OBJECT: { // Base oops are OK, but not derived oops
478 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
479 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
480 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
481 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
482 // have a Phi for the base here that we convert to a CMOVE all is well
483 // and good. But if the base is dead, we'll not make a CMOVE. Later
484 // the allocator will have to produce a base by creating a CMOVE of the
485 // relevant bases. This puts the allocator in the business of
486 // manufacturing expensive instructions, generally a bad plan.
487 // Just Say No to Conditionally-Moved Derived Pointers.
488 if( tp && tp->offset() != 0 )
489 return NULL;
490 cost++;
491 break;
492 }
493 default:
494 return NULL; // In particular, can't do memory or I/O
495 }
496 // Add in cost any speculative ops
497 for( uint j = 1; j < region->req(); j++ ) {
498 Node *proj = region->in(j);
499 Node *inp = phi->in(j);
500 if (get_ctrl(inp) == proj) { // Found local op
501 cost++;
502 // Check for a chain of dependent ops; these will all become
503 // speculative in a CMOV.
504 for( uint k = 1; k < inp->req(); k++ )
505 if (get_ctrl(inp->in(k)) == proj)
506 return NULL; // Too much speculative goo
507 }
508 }
509 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
510 // This will likely Split-If, a higher-payoff operation.
511 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
512 Node* use = phi->fast_out(k);
513 if( use->is_Cmp() || use->is_DecodeN() || use->is_EncodeP() )
514 return NULL;
515 }
516 }
517 if( cost >= ConditionalMoveLimit ) return NULL; // Too much goo
518 Node* bol = iff->in(1);
519 assert( bol->Opcode() == Op_Bool, "" );
520 int cmp_op = bol->in(1)->Opcode();
521 // It is expensive to generate flags from a float compare.
522 // Avoid duplicated float compare.
523 if( phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
524
525 // --------------
526 // Now replace all Phis with CMOV's
527 Node *cmov_ctrl = iff->in(0);
528 uint flip = (lp->Opcode() == Op_IfTrue);
529 while( 1 ) {
530 PhiNode* phi = NULL;
531 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
532 Node *out = region->fast_out(i);
533 if (out->is_Phi()) {
534 phi = out->as_Phi();
535 break;
536 }
537 }
538 if (phi == NULL) break;
539 #ifndef PRODUCT
540 if( PrintOpto && VerifyLoopOptimizations ) tty->print_cr("CMOV");
541 #endif
542 // Move speculative ops
543 for( uint j = 1; j < region->req(); j++ ) {
544 Node *proj = region->in(j);
545 Node *inp = phi->in(j);
546 if (get_ctrl(inp) == proj) { // Found local op
547 #ifndef PRODUCT
548 if( PrintOpto && VerifyLoopOptimizations ) {
549 tty->print(" speculate: ");
550 inp->dump();
551 }
552 #endif
553 set_ctrl(inp, cmov_ctrl);
554 }
555 }
556 Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) );
557 register_new_node( cmov, cmov_ctrl );
558 _igvn.hash_delete(phi);
559 _igvn.subsume_node( phi, cmov );
560 #ifndef PRODUCT
561 if( VerifyLoopOptimizations ) verify();
562 #endif
563 }
564
565 // The useless CFG diamond will fold up later; see the optimization in
566 // RegionNode::Ideal.
567 _igvn._worklist.push(region);
568
569 return iff->in(1);
570 }
571
572 //------------------------------split_if_with_blocks_pre-----------------------
573 // Do the real work in a non-recursive function. Data nodes want to be
574 // cloned in the pre-order so they can feed each other nicely.
575 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
576 // Cloning these guys is unlikely to win
577 int n_op = n->Opcode();
578 if( n_op == Op_MergeMem ) return n;
579 if( n->is_Proj() ) return n;
580 // Do not clone-up CmpFXXX variations, as these are always
581 // followed by a CmpI
582 if( n->is_Cmp() ) return n;
583 // Attempt to use a conditional move instead of a phi/branch
584 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
585 Node *cmov = conditional_move( n );
586 if( cmov ) return cmov;
587 }
588 if( n->is_CFG() || n->is_LoadStore() )
589 return n;
590 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
591 n_op == Op_Opaque2 ) {
592 if( !C->major_progress() ) // If chance of no more loop opts...
593 _igvn._worklist.push(n); // maybe we'll remove them
594 return n;
595 }
596
597 if( n->is_Con() ) return n; // No cloning for Con nodes
598
599 Node *n_ctrl = get_ctrl(n);
600 if( !n_ctrl ) return n; // Dead node
601
602 // Attempt to remix address expressions for loop invariants
603 Node *m = remix_address_expressions( n );
604 if( m ) return m;
605
606 // Determine if the Node has inputs from some local Phi.
607 // Returns the block to clone thru.
608 Node *n_blk = has_local_phi_input( n );
609 if( !n_blk ) return n;
610 // Do not clone the trip counter through on a CountedLoop
611 // (messes up the canonical shape).
612 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
613
614 // Check for having no control input; not pinned. Allow
615 // dominating control.
616 if( n->in(0) ) {
617 Node *dom = idom(n_blk);
618 if( dom_lca( n->in(0), dom ) != n->in(0) )
619 return n;
620 }
621 // Policy: when is it profitable. You must get more wins than
622 // policy before it is considered profitable. Policy is usually 0,
623 // so 1 win is considered profitable. Big merges will require big
624 // cloning, so get a larger policy.
625 int policy = n_blk->req() >> 2;
626
627 // If the loop is a candidate for range check elimination,
628 // delay splitting through it's phi until a later loop optimization
629 if (n_blk->is_CountedLoop()) {
630 IdealLoopTree *lp = get_loop(n_blk);
631 if (lp && lp->_rce_candidate) {
632 return n;
633 }
634 }
635
636 // Use same limit as split_if_with_blocks_post
637 if( C->unique() > 35000 ) return n; // Method too big
638
639 // Split 'n' through the merge point if it is profitable
640 Node *phi = split_thru_phi( n, n_blk, policy );
641 if( !phi ) return n;
642
643 // Found a Phi to split thru!
644 // Replace 'n' with the new phi
645 _igvn.hash_delete(n);
646 _igvn.subsume_node( n, phi );
647 // Moved a load around the loop, 'en-registering' something.
648 if( n_blk->Opcode() == Op_Loop && n->is_Load() &&
649 !phi->in(LoopNode::LoopBackControl)->is_Load() )
650 C->set_major_progress();
651
652 return phi;
653 }
654
655 static bool merge_point_too_heavy(Compile* C, Node* region) {
656 // Bail out if the region and its phis have too many users.
657 int weight = 0;
658 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
659 weight += region->fast_out(i)->outcnt();
660 }
661 int nodes_left = MaxNodeLimit - C->unique();
662 if (weight * 8 > nodes_left) {
663 #ifndef PRODUCT
664 if (PrintOpto)
665 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
666 #endif
667 return true;
668 } else {
669 return false;
670 }
671 }
672
673 static bool merge_point_safe(Node* region) {
674 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
675 // having a PhiNode input. This sidesteps the dangerous case where the split
676 // ConvI2LNode may become TOP if the input Value() does not
677 // overlap the ConvI2L range, leaving a node which may not dominate its
678 // uses.
679 // A better fix for this problem can be found in the BugTraq entry, but
680 // expediency for Mantis demands this hack.
681 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
682 // split_if_with_blocks from splitting a block because we could not move around
683 // the FastLockNode.
684 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
685 Node* n = region->fast_out(i);
686 if (n->is_Phi()) {
687 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
688 Node* m = n->fast_out(j);
689 if (m->is_FastLock())
690 return false;
691 #ifdef _LP64
692 if (m->Opcode() == Op_ConvI2L)
693 return false;
694 #endif
695 }
696 }
697 }
698 return true;
699 }
700
701
702 //------------------------------place_near_use---------------------------------
703 // Place some computation next to use but not inside inner loops.
704 // For inner loop uses move it to the preheader area.
705 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
706 IdealLoopTree *u_loop = get_loop( useblock );
707 return (u_loop->_irreducible || u_loop->_child)
708 ? useblock
709 : u_loop->_head->in(LoopNode::EntryControl);
710 }
711
712
713 //------------------------------split_if_with_blocks_post----------------------
714 // Do the real work in a non-recursive function. CFG hackery wants to be
715 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
716 // info.
717 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
718
719 // Cloning Cmp through Phi's involves the split-if transform.
720 // FastLock is not used by an If
721 if( n->is_Cmp() && !n->is_FastLock() ) {
722 if( C->unique() > 35000 ) return; // Method too big
723
724 // Do not do 'split-if' if irreducible loops are present.
725 if( _has_irreducible_loops )
726 return;
727
728 Node *n_ctrl = get_ctrl(n);
729 // Determine if the Node has inputs from some local Phi.
730 // Returns the block to clone thru.
731 Node *n_blk = has_local_phi_input( n );
732 if( n_blk != n_ctrl ) return;
733
734 if( merge_point_too_heavy(C, n_ctrl) )
735 return;
736
737 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
738 Node *bol = n->unique_out();
739 assert( bol->is_Bool(), "expect a bool here" );
740 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
741 Node *iff = bol->unique_out();
742
743 // Check some safety conditions
744 if( iff->is_If() ) { // Classic split-if?
745 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
746 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
747 if( get_ctrl(iff->in(2)) == n_ctrl ||
748 get_ctrl(iff->in(3)) == n_ctrl )
749 return; // Inputs not yet split-up
750 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
751 return; // Loop-invar test gates loop-varying CMOVE
752 }
753 } else {
754 return; // some other kind of node, such as an Allocate
755 }
756
757 // Do not do 'split-if' if some paths are dead. First do dead code
758 // elimination and then see if its still profitable.
759 for( uint i = 1; i < n_ctrl->req(); i++ )
760 if( n_ctrl->in(i) == C->top() )
761 return;
762
763 // When is split-if profitable? Every 'win' on means some control flow
764 // goes dead, so it's almost always a win.
765 int policy = 0;
766 // If trying to do a 'Split-If' at the loop head, it is only
767 // profitable if the cmp folds up on BOTH paths. Otherwise we
768 // risk peeling a loop forever.
769
770 // CNC - Disabled for now. Requires careful handling of loop
771 // body selection for the cloned code. Also, make sure we check
772 // for any input path not being in the same loop as n_ctrl. For
773 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
774 // because the alternative loop entry points won't be converted
775 // into LoopNodes.
776 IdealLoopTree *n_loop = get_loop(n_ctrl);
777 for( uint j = 1; j < n_ctrl->req(); j++ )
778 if( get_loop(n_ctrl->in(j)) != n_loop )
779 return;
780
781 // Check for safety of the merge point.
782 if( !merge_point_safe(n_ctrl) ) {
783 return;
784 }
785
786 // Split compare 'n' through the merge point if it is profitable
787 Node *phi = split_thru_phi( n, n_ctrl, policy );
788 if( !phi ) return;
789
790 // Found a Phi to split thru!
791 // Replace 'n' with the new phi
792 _igvn.hash_delete(n);
793 _igvn.subsume_node( n, phi );
794
795 // Now split the bool up thru the phi
796 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
797 _igvn.hash_delete(bol);
798 _igvn.subsume_node( bol, bolphi );
799 assert( iff->in(1) == bolphi, "" );
800 if( bolphi->Value(&_igvn)->singleton() )
801 return;
802
803 // Conditional-move? Must split up now
804 if( !iff->is_If() ) {
805 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
806 _igvn.hash_delete(iff);
807 _igvn.subsume_node( iff, cmovphi );
808 return;
809 }
810
811 // Now split the IF
812 do_split_if( iff );
813 return;
814 }
815
816 // Check for an IF ready to split; one that has its
817 // condition codes input coming from a Phi at the block start.
818 int n_op = n->Opcode();
819
820 // Check for an IF being dominated by another IF same test
821 if( n_op == Op_If ) {
822 Node *bol = n->in(1);
823 uint max = bol->outcnt();
824 // Check for same test used more than once?
825 if( n_op == Op_If && max > 1 && bol->is_Bool() ) {
826 // Search up IDOMs to see if this IF is dominated.
827 Node *cutoff = get_ctrl(bol);
828
829 // Now search up IDOMs till cutoff, looking for a dominating test
830 Node *prevdom = n;
831 Node *dom = idom(prevdom);
832 while( dom != cutoff ) {
833 if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) {
834 // Replace the dominated test with an obvious true or false.
835 // Place it on the IGVN worklist for later cleanup.
836 C->set_major_progress();
837 dominated_by( prevdom, n );
838 #ifndef PRODUCT
839 if( VerifyLoopOptimizations ) verify();
840 #endif
841 return;
842 }
843 prevdom = dom;
844 dom = idom(prevdom);
845 }
846 }
847 }
848
849 // See if a shared loop-varying computation has no loop-varying uses.
850 // Happens if something is only used for JVM state in uncommon trap exits,
851 // like various versions of induction variable+offset. Clone the
852 // computation per usage to allow it to sink out of the loop.
853 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
854 Node *n_ctrl = get_ctrl(n);
855 IdealLoopTree *n_loop = get_loop(n_ctrl);
856 if( n_loop != _ltree_root ) {
857 DUIterator_Fast imax, i = n->fast_outs(imax);
858 for (; i < imax; i++) {
859 Node* u = n->fast_out(i);
860 if( !has_ctrl(u) ) break; // Found control user
861 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
862 if( u_loop == n_loop ) break; // Found loop-varying use
863 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
864 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
865 }
866 bool did_break = (i < imax); // Did we break out of the previous loop?
867 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
868 Node *late_load_ctrl;
869 if (n->is_Load()) {
870 // If n is a load, get and save the result from get_late_ctrl(),
871 // to be later used in calculating the control for n's clones.
872 clear_dom_lca_tags();
873 late_load_ctrl = get_late_ctrl(n, n_ctrl);
874 }
875 // If n is a load, and the late control is the same as the current
876 // control, then the cloning of n is a pointless exercise, because
877 // GVN will ensure that we end up where we started.
878 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
879 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
880 Node *u = n->last_out(j); // Clone private computation per use
881 _igvn.hash_delete(u);
882 _igvn._worklist.push(u);
883 Node *x = n->clone(); // Clone computation
884 Node *x_ctrl = NULL;
885 if( u->is_Phi() ) {
886 // Replace all uses of normal nodes. Replace Phi uses
887 // individually, so the separate Nodes can sink down
888 // different paths.
889 uint k = 1;
890 while( u->in(k) != n ) k++;
891 u->set_req( k, x );
892 // x goes next to Phi input path
893 x_ctrl = u->in(0)->in(k);
894 --j;
895 } else { // Normal use
896 // Replace all uses
897 for( uint k = 0; k < u->req(); k++ ) {
898 if( u->in(k) == n ) {
899 u->set_req( k, x );
900 --j;
901 }
902 }
903 x_ctrl = get_ctrl(u);
904 }
905
906 // Find control for 'x' next to use but not inside inner loops.
907 // For inner loop uses get the preheader area.
908 x_ctrl = place_near_use(x_ctrl);
909
910 if (n->is_Load()) {
911 // For loads, add a control edge to a CFG node outside of the loop
912 // to force them to not combine and return back inside the loop
913 // during GVN optimization (4641526).
914 //
915 // Because we are setting the actual control input, factor in
916 // the result from get_late_ctrl() so we respect any
917 // anti-dependences. (6233005).
918 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
919
920 // Don't allow the control input to be a CFG splitting node.
921 // Such nodes should only have ProjNodes as outs, e.g. IfNode
922 // should only have IfTrueNode and IfFalseNode (4985384).
923 x_ctrl = find_non_split_ctrl(x_ctrl);
924 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
925
926 x->set_req(0, x_ctrl);
927 }
928 register_new_node(x, x_ctrl);
929
930 // Some institutional knowledge is needed here: 'x' is
931 // yanked because if the optimizer runs GVN on it all the
932 // cloned x's will common up and undo this optimization and
933 // be forced back in the loop. This is annoying because it
934 // makes +VerifyOpto report false-positives on progress. I
935 // tried setting control edges on the x's to force them to
936 // not combine, but the matching gets worried when it tries
937 // to fold a StoreP and an AddP together (as part of an
938 // address expression) and the AddP and StoreP have
939 // different controls.
940 if( !x->is_Load() && !x->is_DecodeN() ) _igvn._worklist.yank(x);
941 }
942 _igvn.remove_dead_node(n);
943 }
944 }
945 }
946 }
947
948 // Check for Opaque2's who's loop has disappeared - who's input is in the
949 // same loop nest as their output. Remove 'em, they are no longer useful.
950 if( n_op == Op_Opaque2 &&
951 n->in(1) != NULL &&
952 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
953 _igvn.add_users_to_worklist(n);
954 _igvn.hash_delete(n);
955 _igvn.subsume_node( n, n->in(1) );
956 }
957 }
958
959 //------------------------------split_if_with_blocks---------------------------
960 // Check for aggressive application of 'split-if' optimization,
961 // using basic block level info.
962 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
963 Node *n = C->root();
964 visited.set(n->_idx); // first, mark node as visited
965 // Do pre-visit work for root
966 n = split_if_with_blocks_pre( n );
967 uint cnt = n->outcnt();
968 uint i = 0;
969 while (true) {
970 // Visit all children
971 if (i < cnt) {
972 Node* use = n->raw_out(i);
973 ++i;
974 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
975 // Now do pre-visit work for this use
976 use = split_if_with_blocks_pre( use );
977 nstack.push(n, i); // Save parent and next use's index.
978 n = use; // Process all children of current use.
979 cnt = use->outcnt();
980 i = 0;
981 }
982 }
983 else {
984 // All of n's children have been processed, complete post-processing.
985 if (cnt != 0 && !n->is_Con()) {
986 assert(has_node(n), "no dead nodes");
987 split_if_with_blocks_post( n );
988 }
989 if (nstack.is_empty()) {
990 // Finished all nodes on stack.
991 break;
992 }
993 // Get saved parent node and next use's index. Visit the rest of uses.
994 n = nstack.node();
995 cnt = n->outcnt();
996 i = nstack.index();
997 nstack.pop();
998 }
999 }
1000 }
1001
1002
1003 //=============================================================================
1004 //
1005 // C L O N E A L O O P B O D Y
1006 //
1007
1008 //------------------------------clone_iff--------------------------------------
1009 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1010 // "Nearly" because all Nodes have been cloned from the original in the loop,
1011 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1012 // through the Phi recursively, and return a Bool.
1013 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1014
1015 // Convert this Phi into a Phi merging Bools
1016 uint i;
1017 for( i = 1; i < phi->req(); i++ ) {
1018 Node *b = phi->in(i);
1019 if( b->is_Phi() ) {
1020 _igvn.hash_delete(phi);
1021 _igvn._worklist.push(phi);
1022 phi->set_req(i, clone_iff( b->as_Phi(), loop ));
1023 } else {
1024 assert( b->is_Bool(), "" );
1025 }
1026 }
1027
1028 Node *sample_bool = phi->in(1);
1029 Node *sample_cmp = sample_bool->in(1);
1030
1031 // Make Phis to merge the Cmp's inputs.
1032 int size = phi->in(0)->req();
1033 PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1034 PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1035 for( i = 1; i < phi->req(); i++ ) {
1036 Node *n1 = phi->in(i)->in(1)->in(1);
1037 Node *n2 = phi->in(i)->in(1)->in(2);
1038 phi1->set_req( i, n1 );
1039 phi2->set_req( i, n2 );
1040 phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
1041 phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
1042 }
1043 // See if these Phis have been made before.
1044 // Register with optimizer
1045 Node *hit1 = _igvn.hash_find_insert(phi1);
1046 if( hit1 ) { // Hit, toss just made Phi
1047 _igvn.remove_dead_node(phi1); // Remove new phi
1048 assert( hit1->is_Phi(), "" );
1049 phi1 = (PhiNode*)hit1; // Use existing phi
1050 } else { // Miss
1051 _igvn.register_new_node_with_optimizer(phi1);
1052 }
1053 Node *hit2 = _igvn.hash_find_insert(phi2);
1054 if( hit2 ) { // Hit, toss just made Phi
1055 _igvn.remove_dead_node(phi2); // Remove new phi
1056 assert( hit2->is_Phi(), "" );
1057 phi2 = (PhiNode*)hit2; // Use existing phi
1058 } else { // Miss
1059 _igvn.register_new_node_with_optimizer(phi2);
1060 }
1061 // Register Phis with loop/block info
1062 set_ctrl(phi1, phi->in(0));
1063 set_ctrl(phi2, phi->in(0));
1064 // Make a new Cmp
1065 Node *cmp = sample_cmp->clone();
1066 cmp->set_req( 1, phi1 );
1067 cmp->set_req( 2, phi2 );
1068 _igvn.register_new_node_with_optimizer(cmp);
1069 set_ctrl(cmp, phi->in(0));
1070
1071 // Make a new Bool
1072 Node *b = sample_bool->clone();
1073 b->set_req(1,cmp);
1074 _igvn.register_new_node_with_optimizer(b);
1075 set_ctrl(b, phi->in(0));
1076
1077 assert( b->is_Bool(), "" );
1078 return (BoolNode*)b;
1079 }
1080
1081 //------------------------------clone_bool-------------------------------------
1082 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1083 // "Nearly" because all Nodes have been cloned from the original in the loop,
1084 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1085 // through the Phi recursively, and return a Bool.
1086 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1087 uint i;
1088 // Convert this Phi into a Phi merging Bools
1089 for( i = 1; i < phi->req(); i++ ) {
1090 Node *b = phi->in(i);
1091 if( b->is_Phi() ) {
1092 _igvn.hash_delete(phi);
1093 _igvn._worklist.push(phi);
1094 phi->set_req(i, clone_bool( b->as_Phi(), loop ));
1095 } else {
1096 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1097 }
1098 }
1099
1100 Node *sample_cmp = phi->in(1);
1101
1102 // Make Phis to merge the Cmp's inputs.
1103 int size = phi->in(0)->req();
1104 PhiNode *phi1 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1105 PhiNode *phi2 = new (C, size) PhiNode( phi->in(0), Type::TOP );
1106 for( uint j = 1; j < phi->req(); j++ ) {
1107 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1108 Node *n1, *n2;
1109 if( cmp_top->is_Cmp() ) {
1110 n1 = cmp_top->in(1);
1111 n2 = cmp_top->in(2);
1112 } else {
1113 n1 = n2 = cmp_top;
1114 }
1115 phi1->set_req( j, n1 );
1116 phi2->set_req( j, n2 );
1117 phi1->set_type( phi1->type()->meet(n1->bottom_type()) );
1118 phi2->set_type( phi2->type()->meet(n2->bottom_type()) );
1119 }
1120
1121 // See if these Phis have been made before.
1122 // Register with optimizer
1123 Node *hit1 = _igvn.hash_find_insert(phi1);
1124 if( hit1 ) { // Hit, toss just made Phi
1125 _igvn.remove_dead_node(phi1); // Remove new phi
1126 assert( hit1->is_Phi(), "" );
1127 phi1 = (PhiNode*)hit1; // Use existing phi
1128 } else { // Miss
1129 _igvn.register_new_node_with_optimizer(phi1);
1130 }
1131 Node *hit2 = _igvn.hash_find_insert(phi2);
1132 if( hit2 ) { // Hit, toss just made Phi
1133 _igvn.remove_dead_node(phi2); // Remove new phi
1134 assert( hit2->is_Phi(), "" );
1135 phi2 = (PhiNode*)hit2; // Use existing phi
1136 } else { // Miss
1137 _igvn.register_new_node_with_optimizer(phi2);
1138 }
1139 // Register Phis with loop/block info
1140 set_ctrl(phi1, phi->in(0));
1141 set_ctrl(phi2, phi->in(0));
1142 // Make a new Cmp
1143 Node *cmp = sample_cmp->clone();
1144 cmp->set_req( 1, phi1 );
1145 cmp->set_req( 2, phi2 );
1146 _igvn.register_new_node_with_optimizer(cmp);
1147 set_ctrl(cmp, phi->in(0));
1148
1149 assert( cmp->is_Cmp(), "" );
1150 return (CmpNode*)cmp;
1151 }
1152
1153 //------------------------------sink_use---------------------------------------
1154 // If 'use' was in the loop-exit block, it now needs to be sunk
1155 // below the post-loop merge point.
1156 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1157 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1158 set_ctrl(use, post_loop);
1159 for (DUIterator j = use->outs(); use->has_out(j); j++)
1160 sink_use(use->out(j), post_loop);
1161 }
1162 }
1163
1164 //------------------------------clone_loop-------------------------------------
1165 //
1166 // C L O N E A L O O P B O D Y
1167 //
1168 // This is the basic building block of the loop optimizations. It clones an
1169 // entire loop body. It makes an old_new loop body mapping; with this mapping
1170 // you can find the new-loop equivalent to an old-loop node. All new-loop
1171 // nodes are exactly equal to their old-loop counterparts, all edges are the
1172 // same. All exits from the old-loop now have a RegionNode that merges the
1173 // equivalent new-loop path. This is true even for the normal "loop-exit"
1174 // condition. All uses of loop-invariant old-loop values now come from (one
1175 // or more) Phis that merge their new-loop equivalents.
1176 //
1177 // This operation leaves the graph in an illegal state: there are two valid
1178 // control edges coming from the loop pre-header to both loop bodies. I'll
1179 // definitely have to hack the graph after running this transform.
1180 //
1181 // From this building block I will further edit edges to perform loop peeling
1182 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1183 //
1184 // Parameter side_by_size_idom:
1185 // When side_by_size_idom is NULL, the dominator tree is constructed for
1186 // the clone loop to dominate the original. Used in construction of
1187 // pre-main-post loop sequence.
1188 // When nonnull, the clone and original are side-by-side, both are
1189 // dominated by the side_by_side_idom node. Used in construction of
1190 // unswitched loops.
1191 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1192 Node* side_by_side_idom) {
1193
1194 // Step 1: Clone the loop body. Make the old->new mapping.
1195 uint i;
1196 for( i = 0; i < loop->_body.size(); i++ ) {
1197 Node *old = loop->_body.at(i);
1198 Node *nnn = old->clone();
1199 old_new.map( old->_idx, nnn );
1200 _igvn.register_new_node_with_optimizer(nnn);
1201 }
1202
1203
1204 // Step 2: Fix the edges in the new body. If the old input is outside the
1205 // loop use it. If the old input is INside the loop, use the corresponding
1206 // new node instead.
1207 for( i = 0; i < loop->_body.size(); i++ ) {
1208 Node *old = loop->_body.at(i);
1209 Node *nnn = old_new[old->_idx];
1210 // Fix CFG/Loop controlling the new node
1211 if (has_ctrl(old)) {
1212 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1213 } else {
1214 set_loop(nnn, loop->_parent);
1215 if (old->outcnt() > 0) {
1216 set_idom( nnn, old_new[idom(old)->_idx], dd );
1217 }
1218 }
1219 // Correct edges to the new node
1220 for( uint j = 0; j < nnn->req(); j++ ) {
1221 Node *n = nnn->in(j);
1222 if( n ) {
1223 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1224 if( loop->is_member( old_in_loop ) )
1225 nnn->set_req(j, old_new[n->_idx]);
1226 }
1227 }
1228 _igvn.hash_find_insert(nnn);
1229 }
1230 Node *newhead = old_new[loop->_head->_idx];
1231 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1232
1233
1234 // Step 3: Now fix control uses. Loop varying control uses have already
1235 // been fixed up (as part of all input edges in Step 2). Loop invariant
1236 // control uses must be either an IfFalse or an IfTrue. Make a merge
1237 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1238 // refer to this.
1239 ResourceArea *area = Thread::current()->resource_area();
1240 Node_List worklist(area);
1241 uint new_counter = C->unique();
1242 for( i = 0; i < loop->_body.size(); i++ ) {
1243 Node* old = loop->_body.at(i);
1244 if( !old->is_CFG() ) continue;
1245 Node* nnn = old_new[old->_idx];
1246
1247 // Copy uses to a worklist, so I can munge the def-use info
1248 // with impunity.
1249 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1250 worklist.push(old->fast_out(j));
1251
1252 while( worklist.size() ) { // Visit all uses
1253 Node *use = worklist.pop();
1254 if (!has_node(use)) continue; // Ignore dead nodes
1255 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1256 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1257 // Both OLD and USE are CFG nodes here.
1258 assert( use->is_Proj(), "" );
1259
1260 // Clone the loop exit control projection
1261 Node *newuse = use->clone();
1262 newuse->set_req(0,nnn);
1263 _igvn.register_new_node_with_optimizer(newuse);
1264 set_loop(newuse, use_loop);
1265 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1266
1267 // We need a Region to merge the exit from the peeled body and the
1268 // exit from the old loop body.
1269 RegionNode *r = new (C, 3) RegionNode(3);
1270 // Map the old use to the new merge point
1271 old_new.map( use->_idx, r );
1272 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1273 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1274
1275 // The original user of 'use' uses 'r' instead.
1276 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1277 Node* useuse = use->last_out(l);
1278 _igvn.hash_delete(useuse);
1279 _igvn._worklist.push(useuse);
1280 uint uses_found = 0;
1281 if( useuse->in(0) == use ) {
1282 useuse->set_req(0, r);
1283 uses_found++;
1284 if( useuse->is_CFG() ) {
1285 assert( dom_depth(useuse) > dd_r, "" );
1286 set_idom(useuse, r, dom_depth(useuse));
1287 }
1288 }
1289 for( uint k = 1; k < useuse->req(); k++ ) {
1290 if( useuse->in(k) == use ) {
1291 useuse->set_req(k, r);
1292 uses_found++;
1293 }
1294 }
1295 l -= uses_found; // we deleted 1 or more copies of this edge
1296 }
1297
1298 // Now finish up 'r'
1299 r->set_req( 1, newuse );
1300 r->set_req( 2, use );
1301 _igvn.register_new_node_with_optimizer(r);
1302 set_loop(r, use_loop);
1303 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1304 } // End of if a loop-exit test
1305 }
1306 }
1307
1308 // Step 4: If loop-invariant use is not control, it must be dominated by a
1309 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1310 // there if needed. Make a Phi there merging old and new used values.
1311 Node_List *split_if_set = NULL;
1312 Node_List *split_bool_set = NULL;
1313 Node_List *split_cex_set = NULL;
1314 for( i = 0; i < loop->_body.size(); i++ ) {
1315 Node* old = loop->_body.at(i);
1316 Node* nnn = old_new[old->_idx];
1317 // Copy uses to a worklist, so I can munge the def-use info
1318 // with impunity.
1319 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1320 worklist.push(old->fast_out(j));
1321
1322 while( worklist.size() ) {
1323 Node *use = worklist.pop();
1324 if (!has_node(use)) continue; // Ignore dead nodes
1325 if (use->in(0) == C->top()) continue;
1326 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1327 // Check for data-use outside of loop - at least one of OLD or USE
1328 // must not be a CFG node.
1329 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1330
1331 // If the Data use is an IF, that means we have an IF outside of the
1332 // loop that is switching on a condition that is set inside of the
1333 // loop. Happens if people set a loop-exit flag; then test the flag
1334 // in the loop to break the loop, then test is again outside of the
1335 // loop to determine which way the loop exited.
1336 if( use->is_If() || use->is_CMove() ) {
1337 // Since this code is highly unlikely, we lazily build the worklist
1338 // of such Nodes to go split.
1339 if( !split_if_set )
1340 split_if_set = new Node_List(area);
1341 split_if_set->push(use);
1342 }
1343 if( use->is_Bool() ) {
1344 if( !split_bool_set )
1345 split_bool_set = new Node_List(area);
1346 split_bool_set->push(use);
1347 }
1348 if( use->Opcode() == Op_CreateEx ) {
1349 if( !split_cex_set )
1350 split_cex_set = new Node_List(area);
1351 split_cex_set->push(use);
1352 }
1353
1354
1355 // Get "block" use is in
1356 uint idx = 0;
1357 while( use->in(idx) != old ) idx++;
1358 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1359 assert( !loop->is_member( get_loop( prev ) ), "" );
1360 Node *cfg = prev->_idx >= new_counter
1361 ? prev->in(2)
1362 : idom(prev);
1363 if( use->is_Phi() ) // Phi use is in prior block
1364 cfg = prev->in(idx); // NOT in block of Phi itself
1365 if (cfg->is_top()) { // Use is dead?
1366 _igvn.hash_delete(use);
1367 _igvn._worklist.push(use);
1368 use->set_req(idx, C->top());
1369 continue;
1370 }
1371
1372 while( !loop->is_member( get_loop( cfg ) ) ) {
1373 prev = cfg;
1374 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1375 }
1376 // If the use occurs after merging several exits from the loop, then
1377 // old value must have dominated all those exits. Since the same old
1378 // value was used on all those exits we did not need a Phi at this
1379 // merge point. NOW we do need a Phi here. Each loop exit value
1380 // is now merged with the peeled body exit; each exit gets its own
1381 // private Phi and those Phis need to be merged here.
1382 Node *phi;
1383 if( prev->is_Region() ) {
1384 if( idx == 0 ) { // Updating control edge?
1385 phi = prev; // Just use existing control
1386 } else { // Else need a new Phi
1387 phi = PhiNode::make( prev, old );
1388 // Now recursively fix up the new uses of old!
1389 for( uint i = 1; i < prev->req(); i++ ) {
1390 worklist.push(phi); // Onto worklist once for each 'old' input
1391 }
1392 }
1393 } else {
1394 // Get new RegionNode merging old and new loop exits
1395 prev = old_new[prev->_idx];
1396 assert( prev, "just made this in step 7" );
1397 if( idx == 0 ) { // Updating control edge?
1398 phi = prev; // Just use existing control
1399 } else { // Else need a new Phi
1400 // Make a new Phi merging data values properly
1401 phi = PhiNode::make( prev, old );
1402 phi->set_req( 1, nnn );
1403 }
1404 }
1405 // If inserting a new Phi, check for prior hits
1406 if( idx != 0 ) {
1407 Node *hit = _igvn.hash_find_insert(phi);
1408 if( hit == NULL ) {
1409 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1410 } else { // or
1411 // Remove the new phi from the graph and use the hit
1412 _igvn.remove_dead_node(phi);
1413 phi = hit; // Use existing phi
1414 }
1415 set_ctrl(phi, prev);
1416 }
1417 // Make 'use' use the Phi instead of the old loop body exit value
1418 _igvn.hash_delete(use);
1419 _igvn._worklist.push(use);
1420 use->set_req(idx, phi);
1421 if( use->_idx >= new_counter ) { // If updating new phis
1422 // Not needed for correctness, but prevents a weak assert
1423 // in AddPNode from tripping (when we end up with different
1424 // base & derived Phis that will become the same after
1425 // IGVN does CSE).
1426 Node *hit = _igvn.hash_find_insert(use);
1427 if( hit ) // Go ahead and re-hash for hits.
1428 _igvn.subsume_node( use, hit );
1429 }
1430
1431 // If 'use' was in the loop-exit block, it now needs to be sunk
1432 // below the post-loop merge point.
1433 sink_use( use, prev );
1434 }
1435 }
1436 }
1437
1438 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1439 // the loop uses a condition set in the loop. The original IF probably
1440 // takes control from one or more OLD Regions (which in turn get from NEW
1441 // Regions). In any case, there will be a set of Phis for each merge point
1442 // from the IF up to where the original BOOL def exists the loop.
1443 if( split_if_set ) {
1444 while( split_if_set->size() ) {
1445 Node *iff = split_if_set->pop();
1446 if( iff->in(1)->is_Phi() ) {
1447 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1448 _igvn.hash_delete(iff);
1449 _igvn._worklist.push(iff);
1450 iff->set_req(1, b);
1451 }
1452 }
1453 }
1454 if( split_bool_set ) {
1455 while( split_bool_set->size() ) {
1456 Node *b = split_bool_set->pop();
1457 Node *phi = b->in(1);
1458 assert( phi->is_Phi(), "" );
1459 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1460 _igvn.hash_delete(b);
1461 _igvn._worklist.push(b);
1462 b->set_req(1, cmp);
1463 }
1464 }
1465 if( split_cex_set ) {
1466 while( split_cex_set->size() ) {
1467 Node *b = split_cex_set->pop();
1468 assert( b->in(0)->is_Region(), "" );
1469 assert( b->in(1)->is_Phi(), "" );
1470 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1471 split_up( b, b->in(0), NULL );
1472 }
1473 }
1474
1475 }
1476
1477
1478 //---------------------- stride_of_possible_iv -------------------------------------
1479 // Looks for an iff/bool/comp with one operand of the compare
1480 // being a cycle involving an add and a phi,
1481 // with an optional truncation (left-shift followed by a right-shift)
1482 // of the add. Returns zero if not an iv.
1483 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1484 Node* trunc1 = NULL;
1485 Node* trunc2 = NULL;
1486 const TypeInt* ttype = NULL;
1487 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1488 return 0;
1489 }
1490 BoolNode* bl = iff->in(1)->as_Bool();
1491 Node* cmp = bl->in(1);
1492 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1493 return 0;
1494 }
1495 // Must have an invariant operand
1496 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1497 return 0;
1498 }
1499 Node* add2 = NULL;
1500 Node* cmp1 = cmp->in(1);
1501 if (cmp1->is_Phi()) {
1502 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1503 Node* phi = cmp1;
1504 for (uint i = 1; i < phi->req(); i++) {
1505 Node* in = phi->in(i);
1506 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1507 &trunc1, &trunc2, &ttype);
1508 if (add && add->in(1) == phi) {
1509 add2 = add->in(2);
1510 break;
1511 }
1512 }
1513 } else {
1514 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1515 Node* addtrunc = cmp1;
1516 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1517 &trunc1, &trunc2, &ttype);
1518 if (add && add->in(1)->is_Phi()) {
1519 Node* phi = add->in(1);
1520 for (uint i = 1; i < phi->req(); i++) {
1521 if (phi->in(i) == addtrunc) {
1522 add2 = add->in(2);
1523 break;
1524 }
1525 }
1526 }
1527 }
1528 if (add2 != NULL) {
1529 const TypeInt* add2t = _igvn.type(add2)->is_int();
1530 if (add2t->is_con()) {
1531 return add2t->get_con();
1532 }
1533 }
1534 return 0;
1535 }
1536
1537
1538 //---------------------- stay_in_loop -------------------------------------
1539 // Return the (unique) control output node that's in the loop (if it exists.)
1540 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1541 Node* unique = NULL;
1542 if (!n) return NULL;
1543 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1544 Node* use = n->fast_out(i);
1545 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1546 if (unique != NULL) {
1547 return NULL;
1548 }
1549 unique = use;
1550 }
1551 }
1552 return unique;
1553 }
1554
1555 //------------------------------ register_node -------------------------------------
1556 // Utility to register node "n" with PhaseIdealLoop
1557 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1558 _igvn.register_new_node_with_optimizer(n);
1559 loop->_body.push(n);
1560 if (n->is_CFG()) {
1561 set_loop(n, loop);
1562 set_idom(n, pred, ddepth);
1563 } else {
1564 set_ctrl(n, pred);
1565 }
1566 }
1567
1568 //------------------------------ proj_clone -------------------------------------
1569 // Utility to create an if-projection
1570 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1571 ProjNode* c = p->clone()->as_Proj();
1572 c->set_req(0, iff);
1573 return c;
1574 }
1575
1576 //------------------------------ short_circuit_if -------------------------------------
1577 // Force the iff control output to be the live_proj
1578 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1579 int proj_con = live_proj->_con;
1580 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1581 Node *con = _igvn.intcon(proj_con);
1582 set_ctrl(con, C->root());
1583 if (iff) {
1584 iff->set_req(1, con);
1585 }
1586 return con;
1587 }
1588
1589 //------------------------------ insert_if_before_proj -------------------------------------
1590 // Insert a new if before an if projection (* - new node)
1591 //
1592 // before
1593 // if(test)
1594 // / \
1595 // v v
1596 // other-proj proj (arg)
1597 //
1598 // after
1599 // if(test)
1600 // / \
1601 // / v
1602 // | * proj-clone
1603 // v |
1604 // other-proj v
1605 // * new_if(relop(cmp[IU](left,right)))
1606 // / \
1607 // v v
1608 // * new-proj proj
1609 // (returned)
1610 //
1611 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1612 IfNode* iff = proj->in(0)->as_If();
1613 IdealLoopTree *loop = get_loop(proj);
1614 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1615 int ddepth = dom_depth(proj);
1616
1617 _igvn.hash_delete(iff);
1618 _igvn._worklist.push(iff);
1619 _igvn.hash_delete(proj);
1620 _igvn._worklist.push(proj);
1621
1622 proj->set_req(0, NULL); // temporary disconnect
1623 ProjNode* proj2 = proj_clone(proj, iff);
1624 register_node(proj2, loop, iff, ddepth);
1625
1626 Node* cmp = Signed ? (Node*) new (C,3)CmpINode(left, right) : (Node*) new (C,3)CmpUNode(left, right);
1627 register_node(cmp, loop, proj2, ddepth);
1628
1629 BoolNode* bol = new (C,2)BoolNode(cmp, relop);
1630 register_node(bol, loop, proj2, ddepth);
1631
1632 IfNode* new_if = new (C,2)IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1633 register_node(new_if, loop, proj2, ddepth);
1634
1635 proj->set_req(0, new_if); // reattach
1636 set_idom(proj, new_if, ddepth);
1637
1638 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1639 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1640
1641 return new_exit;
1642 }
1643
1644 //------------------------------ insert_region_before_proj -------------------------------------
1645 // Insert a region before an if projection (* - new node)
1646 //
1647 // before
1648 // if(test)
1649 // / |
1650 // v |
1651 // proj v
1652 // other-proj
1653 //
1654 // after
1655 // if(test)
1656 // / |
1657 // v |
1658 // * proj-clone v
1659 // | other-proj
1660 // v
1661 // * new-region
1662 // |
1663 // v
1664 // * dum_if
1665 // / \
1666 // v \
1667 // * dum-proj v
1668 // proj
1669 //
1670 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1671 IfNode* iff = proj->in(0)->as_If();
1672 IdealLoopTree *loop = get_loop(proj);
1673 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1674 int ddepth = dom_depth(proj);
1675
1676 _igvn.hash_delete(iff);
1677 _igvn._worklist.push(iff);
1678 _igvn.hash_delete(proj);
1679 _igvn._worklist.push(proj);
1680
1681 proj->set_req(0, NULL); // temporary disconnect
1682 ProjNode* proj2 = proj_clone(proj, iff);
1683 register_node(proj2, loop, iff, ddepth);
1684
1685 RegionNode* reg = new (C,2)RegionNode(2);
1686 reg->set_req(1, proj2);
1687 register_node(reg, loop, iff, ddepth);
1688
1689 IfNode* dum_if = new (C,2)IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
1690 register_node(dum_if, loop, reg, ddepth);
1691
1692 proj->set_req(0, dum_if); // reattach
1693 set_idom(proj, dum_if, ddepth);
1694
1695 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
1696 register_node(dum_proj, loop, dum_if, ddepth);
1697
1698 return reg;
1699 }
1700
1701 //------------------------------ insert_cmpi_loop_exit -------------------------------------
1702 // Clone a signed compare loop exit from an unsigned compare and
1703 // insert it before the unsigned cmp on the stay-in-loop path.
1704 // All new nodes inserted in the dominator tree between the original
1705 // if and it's projections. The original if test is replaced with
1706 // a constant to force the stay-in-loop path.
1707 //
1708 // This is done to make sure that the original if and it's projections
1709 // still dominate the same set of control nodes, that the ctrl() relation
1710 // from data nodes to them is preserved, and that their loop nesting is
1711 // preserved.
1712 //
1713 // before
1714 // if(i <u limit) unsigned compare loop exit
1715 // / |
1716 // v v
1717 // exit-proj stay-in-loop-proj
1718 //
1719 // after
1720 // if(stay-in-loop-const) original if
1721 // / |
1722 // / v
1723 // / if(i < limit) new signed test
1724 // / / |
1725 // / / v
1726 // / / if(i <u limit) new cloned unsigned test
1727 // / / / |
1728 // v v v |
1729 // region |
1730 // | |
1731 // dum-if |
1732 // / | |
1733 // ether | |
1734 // v v
1735 // exit-proj stay-in-loop-proj
1736 //
1737 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
1738 const bool Signed = true;
1739 const bool Unsigned = false;
1740
1741 BoolNode* bol = if_cmpu->in(1)->as_Bool();
1742 if (bol->_test._test != BoolTest::lt) return NULL;
1743 CmpNode* cmpu = bol->in(1)->as_Cmp();
1744 if (cmpu->Opcode() != Op_CmpU) return NULL;
1745 int stride = stride_of_possible_iv(if_cmpu);
1746 if (stride == 0) return NULL;
1747
1748 ProjNode* lp_continue = stay_in_loop(if_cmpu, loop)->as_Proj();
1749 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
1750
1751 Node* limit = NULL;
1752 if (stride > 0) {
1753 limit = cmpu->in(2);
1754 } else {
1755 limit = _igvn.makecon(TypeInt::ZERO);
1756 set_ctrl(limit, C->root());
1757 }
1758 // Create a new region on the exit path
1759 RegionNode* reg = insert_region_before_proj(lp_exit);
1760
1761 // Clone the if-cmpu-true-false using a signed compare
1762 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
1763 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
1764 reg->add_req(cmpi_exit);
1765
1766 // Clone the if-cmpu-true-false
1767 BoolTest::mask rel_u = bol->_test._test;
1768 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
1769 reg->add_req(cmpu_exit);
1770
1771 // Force original if to stay in loop.
1772 short_circuit_if(if_cmpu, lp_continue);
1773
1774 return cmpi_exit->in(0)->as_If();
1775 }
1776
1777 //------------------------------ remove_cmpi_loop_exit -------------------------------------
1778 // Remove a previously inserted signed compare loop exit.
1779 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
1780 Node* lp_proj = stay_in_loop(if_cmp, loop);
1781 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
1782 stay_in_loop(lp_proj, loop)->is_If() &&
1783 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
1784 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
1785 set_ctrl(con, C->root());
1786 if_cmp->set_req(1, con);
1787 }
1788
1789 //------------------------------ scheduled_nodelist -------------------------------------
1790 // Create a post order schedule of nodes that are in the
1791 // "member" set. The list is returned in "sched".
1792 // The first node in "sched" is the loop head, followed by
1793 // nodes which have no inputs in the "member" set, and then
1794 // followed by the nodes that have an immediate input dependence
1795 // on a node in "sched".
1796 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
1797
1798 assert(member.test(loop->_head->_idx), "loop head must be in member set");
1799 Arena *a = Thread::current()->resource_area();
1800 VectorSet visited(a);
1801 Node_Stack nstack(a, loop->_body.size());
1802
1803 Node* n = loop->_head; // top of stack is cached in "n"
1804 uint idx = 0;
1805 visited.set(n->_idx);
1806
1807 // Initially push all with no inputs from within member set
1808 for(uint i = 0; i < loop->_body.size(); i++ ) {
1809 Node *elt = loop->_body.at(i);
1810 if (member.test(elt->_idx)) {
1811 bool found = false;
1812 for (uint j = 0; j < elt->req(); j++) {
1813 Node* def = elt->in(j);
1814 if (def && member.test(def->_idx) && def != elt) {
1815 found = true;
1816 break;
1817 }
1818 }
1819 if (!found && elt != loop->_head) {
1820 nstack.push(n, idx);
1821 n = elt;
1822 assert(!visited.test(n->_idx), "not seen yet");
1823 visited.set(n->_idx);
1824 }
1825 }
1826 }
1827
1828 // traverse out's that are in the member set
1829 while (true) {
1830 if (idx < n->outcnt()) {
1831 Node* use = n->raw_out(idx);
1832 idx++;
1833 if (!visited.test_set(use->_idx)) {
1834 if (member.test(use->_idx)) {
1835 nstack.push(n, idx);
1836 n = use;
1837 idx = 0;
1838 }
1839 }
1840 } else {
1841 // All outputs processed
1842 sched.push(n);
1843 if (nstack.is_empty()) break;
1844 n = nstack.node();
1845 idx = nstack.index();
1846 nstack.pop();
1847 }
1848 }
1849 }
1850
1851
1852 //------------------------------ has_use_in_set -------------------------------------
1853 // Has a use in the vector set
1854 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
1855 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1856 Node* use = n->fast_out(j);
1857 if (vset.test(use->_idx)) {
1858 return true;
1859 }
1860 }
1861 return false;
1862 }
1863
1864
1865 //------------------------------ has_use_internal_to_set -------------------------------------
1866 // Has use internal to the vector set (ie. not in a phi at the loop head)
1867 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
1868 Node* head = loop->_head;
1869 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1870 Node* use = n->fast_out(j);
1871 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
1872 return true;
1873 }
1874 }
1875 return false;
1876 }
1877
1878
1879 //------------------------------ clone_for_use_outside_loop -------------------------------------
1880 // clone "n" for uses that are outside of loop
1881 void PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
1882
1883 assert(worklist.size() == 0, "should be empty");
1884 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1885 Node* use = n->fast_out(j);
1886 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
1887 worklist.push(use);
1888 }
1889 }
1890 while( worklist.size() ) {
1891 Node *use = worklist.pop();
1892 if (!has_node(use) || use->in(0) == C->top()) continue;
1893 uint j;
1894 for (j = 0; j < use->req(); j++) {
1895 if (use->in(j) == n) break;
1896 }
1897 assert(j < use->req(), "must be there");
1898
1899 // clone "n" and insert it between the inputs of "n" and the use outside the loop
1900 Node* n_clone = n->clone();
1901 _igvn.hash_delete(use);
1902 use->set_req(j, n_clone);
1903 _igvn._worklist.push(use);
1904 Node* use_c;
1905 if (!use->is_Phi()) {
1906 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
1907 } else {
1908 // Use in a phi is considered a use in the associated predecessor block
1909 use_c = use->in(0)->in(j);
1910 }
1911 set_ctrl(n_clone, use_c);
1912 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
1913 get_loop(use_c)->_body.push(n_clone);
1914 _igvn.register_new_node_with_optimizer(n_clone);
1915 #if !defined(PRODUCT)
1916 if (TracePartialPeeling) {
1917 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
1918 }
1919 #endif
1920 }
1921 }
1922
1923
1924 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
1925 // clone "n" for special uses that are in the not_peeled region.
1926 // If these def-uses occur in separate blocks, the code generator
1927 // marks the method as not compilable. For example, if a "BoolNode"
1928 // is in a different basic block than the "IfNode" that uses it, then
1929 // the compilation is aborted in the code generator.
1930 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1931 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
1932 if (n->is_Phi() || n->is_Load()) {
1933 return;
1934 }
1935 assert(worklist.size() == 0, "should be empty");
1936 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1937 Node* use = n->fast_out(j);
1938 if ( not_peel.test(use->_idx) &&
1939 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
1940 use->in(1) == n) {
1941 worklist.push(use);
1942 }
1943 }
1944 if (worklist.size() > 0) {
1945 // clone "n" and insert it between inputs of "n" and the use
1946 Node* n_clone = n->clone();
1947 loop->_body.push(n_clone);
1948 _igvn.register_new_node_with_optimizer(n_clone);
1949 set_ctrl(n_clone, get_ctrl(n));
1950 sink_list.push(n_clone);
1951 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
1952 #if !defined(PRODUCT)
1953 if (TracePartialPeeling) {
1954 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
1955 }
1956 #endif
1957 while( worklist.size() ) {
1958 Node *use = worklist.pop();
1959 _igvn.hash_delete(use);
1960 _igvn._worklist.push(use);
1961 for (uint j = 1; j < use->req(); j++) {
1962 if (use->in(j) == n) {
1963 use->set_req(j, n_clone);
1964 }
1965 }
1966 }
1967 }
1968 }
1969
1970
1971 //------------------------------ insert_phi_for_loop -------------------------------------
1972 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1973 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
1974 Node *phi = PhiNode::make(lp, back_edge_val);
1975 phi->set_req(LoopNode::EntryControl, lp_entry_val);
1976 // Use existing phi if it already exists
1977 Node *hit = _igvn.hash_find_insert(phi);
1978 if( hit == NULL ) {
1979 _igvn.register_new_node_with_optimizer(phi);
1980 set_ctrl(phi, lp);
1981 } else {
1982 // Remove the new phi from the graph and use the hit
1983 _igvn.remove_dead_node(phi);
1984 phi = hit;
1985 }
1986 _igvn.hash_delete(use);
1987 _igvn._worklist.push(use);
1988 use->set_req(idx, phi);
1989 }
1990
1991 #ifdef ASSERT
1992 //------------------------------ is_valid_loop_partition -------------------------------------
1993 // Validate the loop partition sets: peel and not_peel
1994 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
1995 VectorSet& not_peel ) {
1996 uint i;
1997 // Check that peel_list entries are in the peel set
1998 for (i = 0; i < peel_list.size(); i++) {
1999 if (!peel.test(peel_list.at(i)->_idx)) {
2000 return false;
2001 }
2002 }
2003 // Check at loop members are in one of peel set or not_peel set
2004 for (i = 0; i < loop->_body.size(); i++ ) {
2005 Node *def = loop->_body.at(i);
2006 uint di = def->_idx;
2007 // Check that peel set elements are in peel_list
2008 if (peel.test(di)) {
2009 if (not_peel.test(di)) {
2010 return false;
2011 }
2012 // Must be in peel_list also
2013 bool found = false;
2014 for (uint j = 0; j < peel_list.size(); j++) {
2015 if (peel_list.at(j)->_idx == di) {
2016 found = true;
2017 break;
2018 }
2019 }
2020 if (!found) {
2021 return false;
2022 }
2023 } else if (not_peel.test(di)) {
2024 if (peel.test(di)) {
2025 return false;
2026 }
2027 } else {
2028 return false;
2029 }
2030 }
2031 return true;
2032 }
2033
2034 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2035 // Ensure a use outside of loop is of the right form
2036 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2037 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2038 return (use->is_Phi() &&
2039 use_c->is_Region() && use_c->req() == 3 &&
2040 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2041 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2042 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2043 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2044 }
2045
2046 //------------------------------ is_valid_clone_loop_form -------------------------------------
2047 // Ensure that all uses outside of loop are of the right form
2048 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2049 uint orig_exit_idx, uint clone_exit_idx) {
2050 uint len = peel_list.size();
2051 for (uint i = 0; i < len; i++) {
2052 Node *def = peel_list.at(i);
2053
2054 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2055 Node *use = def->fast_out(j);
2056 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2057 if (!loop->is_member(get_loop(use_c))) {
2058 // use is not in the loop, check for correct structure
2059 if (use->in(0) == def) {
2060 // Okay
2061 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2062 return false;
2063 }
2064 }
2065 }
2066 }
2067 return true;
2068 }
2069 #endif
2070
2071 //------------------------------ partial_peel -------------------------------------
2072 // Partially peel (aka loop rotation) the top portion of a loop (called
2073 // the peel section below) by cloning it and placing one copy just before
2074 // the new loop head and the other copy at the bottom of the new loop.
2075 //
2076 // before after where it came from
2077 //
2078 // stmt1 stmt1
2079 // loop: stmt2 clone
2080 // stmt2 if condA goto exitA clone
2081 // if condA goto exitA new_loop: new
2082 // stmt3 stmt3 clone
2083 // if !condB goto loop if condB goto exitB clone
2084 // exitB: stmt2 orig
2085 // stmt4 if !condA goto new_loop orig
2086 // exitA: goto exitA
2087 // exitB:
2088 // stmt4
2089 // exitA:
2090 //
2091 // Step 1: find the cut point: an exit test on probable
2092 // induction variable.
2093 // Step 2: schedule (with cloning) operations in the peel
2094 // section that can be executed after the cut into
2095 // the section that is not peeled. This may need
2096 // to clone operations into exit blocks. For
2097 // instance, a reference to A[i] in the not-peel
2098 // section and a reference to B[i] in an exit block
2099 // may cause a left-shift of i by 2 to be placed
2100 // in the peel block. This step will clone the left
2101 // shift into the exit block and sink the left shift
2102 // from the peel to the not-peel section.
2103 // Step 3: clone the loop, retarget the control, and insert
2104 // phis for values that are live across the new loop
2105 // head. This is very dependent on the graph structure
2106 // from clone_loop. It creates region nodes for
2107 // exit control and associated phi nodes for values
2108 // flow out of the loop through that exit. The region
2109 // node is dominated by the clone's control projection.
2110 // So the clone's peel section is placed before the
2111 // new loop head, and the clone's not-peel section is
2112 // forms the top part of the new loop. The original
2113 // peel section forms the tail of the new loop.
2114 // Step 4: update the dominator tree and recompute the
2115 // dominator depth.
2116 //
2117 // orig
2118 //
2119 // stmt1
2120 // |
2121 // v
2122 // loop<----+
2123 // | |
2124 // stmt2 |
2125 // | |
2126 // v |
2127 // ifA |
2128 // / | |
2129 // v v |
2130 // false true ^ <-- last_peel
2131 // / | |
2132 // / ===|==cut |
2133 // / stmt3 | <-- first_not_peel
2134 // / | |
2135 // | v |
2136 // v ifB |
2137 // exitA: / \ |
2138 // / \ |
2139 // v v |
2140 // false true |
2141 // / \ |
2142 // / ----+
2143 // |
2144 // v
2145 // exitB:
2146 // stmt4
2147 //
2148 //
2149 // after clone loop
2150 //
2151 // stmt1
2152 // / \
2153 // clone / \ orig
2154 // / \
2155 // / \
2156 // v v
2157 // +---->loop loop<----+
2158 // | | | |
2159 // | stmt2 stmt2 |
2160 // | | | |
2161 // | v v |
2162 // | ifA ifA |
2163 // | | \ / | |
2164 // | v v v v |
2165 // ^ true false false true ^ <-- last_peel
2166 // | | ^ \ / | |
2167 // | cut==|== \ \ / ===|==cut |
2168 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2169 // | | dom | | | |
2170 // | v \ 1v v2 v |
2171 // | ifB regionA ifB |
2172 // | / \ | / \ |
2173 // | / \ v / \ |
2174 // | v v exitA: v v |
2175 // | true false false true |
2176 // | / ^ \ / \ |
2177 // +---- \ \ / ----+
2178 // dom \ /
2179 // \ 1v v2
2180 // regionB
2181 // |
2182 // v
2183 // exitB:
2184 // stmt4
2185 //
2186 //
2187 // after partial peel
2188 //
2189 // stmt1
2190 // /
2191 // clone / orig
2192 // / TOP
2193 // / \
2194 // v v
2195 // TOP->region region----+
2196 // | | |
2197 // stmt2 stmt2 |
2198 // | | |
2199 // v v |
2200 // ifA ifA |
2201 // | \ / | |
2202 // v v v v |
2203 // true false false true | <-- last_peel
2204 // | ^ \ / +------|---+
2205 // +->newloop \ \ / === ==cut | |
2206 // | stmt3 \ \ / TOP | |
2207 // | | dom | | stmt3 | | <-- first_not_peel
2208 // | v \ 1v v2 v | |
2209 // | ifB regionA ifB ^ v
2210 // | / \ | / \ | |
2211 // | / \ v / \ | |
2212 // | v v exitA: v v | |
2213 // | true false false true | |
2214 // | / ^ \ / \ | |
2215 // | | \ \ / v | |
2216 // | | dom \ / TOP | |
2217 // | | \ 1v v2 | |
2218 // ^ v regionB | |
2219 // | | | | |
2220 // | | v ^ v
2221 // | | exitB: | |
2222 // | | stmt4 | |
2223 // | +------------>-----------------+ |
2224 // | |
2225 // +-----------------<---------------------+
2226 //
2227 //
2228 // final graph
2229 //
2230 // stmt1
2231 // |
2232 // v
2233 // ........> ifA clone
2234 // : / |
2235 // dom / |
2236 // : v v
2237 // : false true
2238 // : | |
2239 // : | stmt2 clone
2240 // : | |
2241 // : | v
2242 // : | newloop<-----+
2243 // : | | |
2244 // : | stmt3 clone |
2245 // : | | |
2246 // : | v |
2247 // : | ifB |
2248 // : | / \ |
2249 // : | v v |
2250 // : | false true |
2251 // : | | | |
2252 // : | v stmt2 |
2253 // : | exitB: | |
2254 // : | stmt4 v |
2255 // : | ifA orig |
2256 // : | / \ |
2257 // : | / \ |
2258 // : | v v |
2259 // : | false true |
2260 // : | / \ |
2261 // : v v -----+
2262 // RegionA
2263 // |
2264 // v
2265 // exitA
2266 //
2267 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2268
2269 if (!loop->_head->is_Loop()) {
2270 return false; }
2271
2272 LoopNode *head = loop->_head->as_Loop();
2273
2274 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2275 return false;
2276 }
2277
2278 // Check for complex exit control
2279 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2280 Node *n = loop->_body.at(ii);
2281 int opc = n->Opcode();
2282 if (n->is_Call() ||
2283 opc == Op_Catch ||
2284 opc == Op_CatchProj ||
2285 opc == Op_Jump ||
2286 opc == Op_JumpProj) {
2287 #if !defined(PRODUCT)
2288 if (TracePartialPeeling) {
2289 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2290 }
2291 #endif
2292 return false;
2293 }
2294 }
2295
2296 int dd = dom_depth(head);
2297
2298 // Step 1: find cut point
2299
2300 // Walk up dominators to loop head looking for first loop exit
2301 // which is executed on every path thru loop.
2302 IfNode *peel_if = NULL;
2303 IfNode *peel_if_cmpu = NULL;
2304
2305 Node *iff = loop->tail();
2306 while( iff != head ) {
2307 if( iff->is_If() ) {
2308 Node *ctrl = get_ctrl(iff->in(1));
2309 if (ctrl->is_top()) return false; // Dead test on live IF.
2310 // If loop-varying exit-test, check for induction variable
2311 if( loop->is_member(get_loop(ctrl)) &&
2312 loop->is_loop_exit(iff) &&
2313 is_possible_iv_test(iff)) {
2314 Node* cmp = iff->in(1)->in(1);
2315 if (cmp->Opcode() == Op_CmpI) {
2316 peel_if = iff->as_If();
2317 } else {
2318 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2319 peel_if_cmpu = iff->as_If();
2320 }
2321 }
2322 }
2323 iff = idom(iff);
2324 }
2325 // Prefer signed compare over unsigned compare.
2326 IfNode* new_peel_if = NULL;
2327 if (peel_if == NULL) {
2328 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2329 return false; // No peel point found
2330 }
2331 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2332 if (new_peel_if == NULL) {
2333 return false; // No peel point found
2334 }
2335 peel_if = new_peel_if;
2336 }
2337 Node* last_peel = stay_in_loop(peel_if, loop);
2338 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2339 if (first_not_peeled == NULL || first_not_peeled == head) {
2340 return false;
2341 }
2342
2343 #if !defined(PRODUCT)
2344 if (TracePartialPeeling) {
2345 tty->print_cr("before partial peel one iteration");
2346 Node_List wl;
2347 Node* t = head->in(2);
2348 while (true) {
2349 wl.push(t);
2350 if (t == head) break;
2351 t = idom(t);
2352 }
2353 while (wl.size() > 0) {
2354 Node* tt = wl.pop();
2355 tt->dump();
2356 if (tt == last_peel) tty->print_cr("-- cut --");
2357 }
2358 }
2359 #endif
2360 ResourceArea *area = Thread::current()->resource_area();
2361 VectorSet peel(area);
2362 VectorSet not_peel(area);
2363 Node_List peel_list(area);
2364 Node_List worklist(area);
2365 Node_List sink_list(area);
2366
2367 // Set of cfg nodes to peel are those that are executable from
2368 // the head through last_peel.
2369 assert(worklist.size() == 0, "should be empty");
2370 worklist.push(head);
2371 peel.set(head->_idx);
2372 while (worklist.size() > 0) {
2373 Node *n = worklist.pop();
2374 if (n != last_peel) {
2375 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2376 Node* use = n->fast_out(j);
2377 if (use->is_CFG() &&
2378 loop->is_member(get_loop(use)) &&
2379 !peel.test_set(use->_idx)) {
2380 worklist.push(use);
2381 }
2382 }
2383 }
2384 }
2385
2386 // Set of non-cfg nodes to peel are those that are control
2387 // dependent on the cfg nodes.
2388 uint i;
2389 for(i = 0; i < loop->_body.size(); i++ ) {
2390 Node *n = loop->_body.at(i);
2391 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2392 if (peel.test(n_c->_idx)) {
2393 peel.set(n->_idx);
2394 } else {
2395 not_peel.set(n->_idx);
2396 }
2397 }
2398
2399 // Step 2: move operations from the peeled section down into the
2400 // not-peeled section
2401
2402 // Get a post order schedule of nodes in the peel region
2403 // Result in right-most operand.
2404 scheduled_nodelist(loop, peel, peel_list );
2405
2406 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2407
2408 // For future check for too many new phis
2409 uint old_phi_cnt = 0;
2410 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2411 Node* use = head->fast_out(j);
2412 if (use->is_Phi()) old_phi_cnt++;
2413 }
2414
2415 #if !defined(PRODUCT)
2416 if (TracePartialPeeling) {
2417 tty->print_cr("\npeeled list");
2418 }
2419 #endif
2420
2421 // Evacuate nodes in peel region into the not_peeled region if possible
2422 uint new_phi_cnt = 0;
2423 for (i = 0; i < peel_list.size();) {
2424 Node* n = peel_list.at(i);
2425 #if !defined(PRODUCT)
2426 if (TracePartialPeeling) n->dump();
2427 #endif
2428 bool incr = true;
2429 if ( !n->is_CFG() ) {
2430
2431 if ( has_use_in_set(n, not_peel) ) {
2432
2433 // If not used internal to the peeled region,
2434 // move "n" from peeled to not_peeled region.
2435
2436 if ( !has_use_internal_to_set(n, peel, loop) ) {
2437
2438 // if not pinned and not a load (which maybe anti-dependent on a store)
2439 // and not a CMove (Matcher expects only bool->cmove).
2440 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2441 clone_for_use_outside_loop( loop, n, worklist );
2442
2443 sink_list.push(n);
2444 peel >>= n->_idx; // delete n from peel set.
2445 not_peel <<= n->_idx; // add n to not_peel set.
2446 peel_list.remove(i);
2447 incr = false;
2448 #if !defined(PRODUCT)
2449 if (TracePartialPeeling) {
2450 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2451 n->_idx, get_ctrl(n)->_idx);
2452 }
2453 #endif
2454 }
2455 } else {
2456 // Otherwise check for special def-use cases that span
2457 // the peel/not_peel boundary such as bool->if
2458 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2459 new_phi_cnt++;
2460 }
2461 }
2462 }
2463 if (incr) i++;
2464 }
2465
2466 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2467 #if !defined(PRODUCT)
2468 if (TracePartialPeeling) {
2469 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2470 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2471 }
2472 #endif
2473 if (new_peel_if != NULL) {
2474 remove_cmpi_loop_exit(new_peel_if, loop);
2475 }
2476 // Inhibit more partial peeling on this loop
2477 assert(!head->is_partial_peel_loop(), "not partial peeled");
2478 head->mark_partial_peel_failed();
2479 return false;
2480 }
2481
2482 // Step 3: clone loop, retarget control, and insert new phis
2483
2484 // Create new loop head for new phis and to hang
2485 // the nodes being moved (sinked) from the peel region.
2486 LoopNode* new_head = new (C, 3) LoopNode(last_peel, last_peel);
2487 _igvn.register_new_node_with_optimizer(new_head);
2488 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2489 first_not_peeled->set_req(0, new_head);
2490 set_loop(new_head, loop);
2491 loop->_body.push(new_head);
2492 not_peel.set(new_head->_idx);
2493 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2494 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2495
2496 while (sink_list.size() > 0) {
2497 Node* n = sink_list.pop();
2498 set_ctrl(n, new_head);
2499 }
2500
2501 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2502
2503 clone_loop( loop, old_new, dd );
2504
2505 const uint clone_exit_idx = 1;
2506 const uint orig_exit_idx = 2;
2507 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2508
2509 Node* head_clone = old_new[head->_idx];
2510 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2511 Node* orig_tail_clone = head_clone->in(2);
2512
2513 // Add phi if "def" node is in peel set and "use" is not
2514
2515 for(i = 0; i < peel_list.size(); i++ ) {
2516 Node *def = peel_list.at(i);
2517 if (!def->is_CFG()) {
2518 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2519 Node *use = def->fast_out(j);
2520 if (has_node(use) && use->in(0) != C->top() &&
2521 (!peel.test(use->_idx) ||
2522 (use->is_Phi() && use->in(0) == head)) ) {
2523 worklist.push(use);
2524 }
2525 }
2526 while( worklist.size() ) {
2527 Node *use = worklist.pop();
2528 for (uint j = 1; j < use->req(); j++) {
2529 Node* n = use->in(j);
2530 if (n == def) {
2531
2532 // "def" is in peel set, "use" is not in peel set
2533 // or "use" is in the entry boundary (a phi) of the peel set
2534
2535 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2536
2537 if ( loop->is_member(get_loop( use_c )) ) {
2538 // use is in loop
2539 if (old_new[use->_idx] != NULL) { // null for dead code
2540 Node* use_clone = old_new[use->_idx];
2541 _igvn.hash_delete(use);
2542 use->set_req(j, C->top());
2543 _igvn._worklist.push(use);
2544 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2545 }
2546 } else {
2547 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2548 // use is not in the loop, check if the live range includes the cut
2549 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2550 if (not_peel.test(lp_if->_idx)) {
2551 assert(j == orig_exit_idx, "use from original loop");
2552 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2553 }
2554 }
2555 }
2556 }
2557 }
2558 }
2559 }
2560
2561 // Step 3b: retarget control
2562
2563 // Redirect control to the new loop head if a cloned node in
2564 // the not_peeled region has control that points into the peeled region.
2565 // This necessary because the cloned peeled region will be outside
2566 // the loop.
2567 // from to
2568 // cloned-peeled <---+
2569 // new_head_clone: | <--+
2570 // cloned-not_peeled in(0) in(0)
2571 // orig-peeled
2572
2573 for(i = 0; i < loop->_body.size(); i++ ) {
2574 Node *n = loop->_body.at(i);
2575 if (!n->is_CFG() && n->in(0) != NULL &&
2576 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2577 Node* n_clone = old_new[n->_idx];
2578 _igvn.hash_delete(n_clone);
2579 n_clone->set_req(0, new_head_clone);
2580 _igvn._worklist.push(n_clone);
2581 }
2582 }
2583
2584 // Backedge of the surviving new_head (the clone) is original last_peel
2585 _igvn.hash_delete(new_head_clone);
2586 new_head_clone->set_req(LoopNode::LoopBackControl, last_peel);
2587 _igvn._worklist.push(new_head_clone);
2588
2589 // Cut first node in original not_peel set
2590 _igvn.hash_delete(new_head);
2591 new_head->set_req(LoopNode::EntryControl, C->top());
2592 new_head->set_req(LoopNode::LoopBackControl, C->top());
2593 _igvn._worklist.push(new_head);
2594
2595 // Copy head_clone back-branch info to original head
2596 // and remove original head's loop entry and
2597 // clone head's back-branch
2598 _igvn.hash_delete(head);
2599 _igvn.hash_delete(head_clone);
2600 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2601 head->set_req(LoopNode::LoopBackControl, C->top());
2602 head_clone->set_req(LoopNode::LoopBackControl, C->top());
2603 _igvn._worklist.push(head);
2604 _igvn._worklist.push(head_clone);
2605
2606 // Similarly modify the phis
2607 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2608 Node* use = head->fast_out(k);
2609 if (use->is_Phi() && use->outcnt() > 0) {
2610 Node* use_clone = old_new[use->_idx];
2611 _igvn.hash_delete(use);
2612 _igvn.hash_delete(use_clone);
2613 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2614 use->set_req(LoopNode::LoopBackControl, C->top());
2615 use_clone->set_req(LoopNode::LoopBackControl, C->top());
2616 _igvn._worklist.push(use);
2617 _igvn._worklist.push(use_clone);
2618 }
2619 }
2620
2621 // Step 4: update dominator tree and dominator depth
2622
2623 set_idom(head, orig_tail_clone, dd);
2624 recompute_dom_depth();
2625
2626 // Inhibit more partial peeling on this loop
2627 new_head_clone->set_partial_peel_loop();
2628 C->set_major_progress();
2629
2630 #if !defined(PRODUCT)
2631 if (TracePartialPeeling) {
2632 tty->print_cr("\nafter partial peel one iteration");
2633 Node_List wl(area);
2634 Node* t = last_peel;
2635 while (true) {
2636 wl.push(t);
2637 if (t == head_clone) break;
2638 t = idom(t);
2639 }
2640 while (wl.size() > 0) {
2641 Node* tt = wl.pop();
2642 if (tt == head) tty->print_cr("orig head");
2643 else if (tt == new_head_clone) tty->print_cr("new head");
2644 else if (tt == head_clone) tty->print_cr("clone head");
2645 tt->dump();
2646 }
2647 }
2648 #endif
2649 return true;
2650 }
2651
2652 //------------------------------reorg_offsets----------------------------------
2653 // Reorganize offset computations to lower register pressure. Mostly
2654 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2655 // then alive with the post-incremented trip counter forcing an extra
2656 // register move)
2657 void PhaseIdealLoop::reorg_offsets( IdealLoopTree *loop ) {
2658
2659 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2660 CountedLoopEndNode *cle = cl->loopexit();
2661 if( !cle ) return; // The occasional dead loop
2662 // Find loop exit control
2663 Node *exit = cle->proj_out(false);
2664 assert( exit->Opcode() == Op_IfFalse, "" );
2665
2666 // Check for the special case of folks using the pre-incremented
2667 // trip-counter on the fall-out path (forces the pre-incremented
2668 // and post-incremented trip counter to be live at the same time).
2669 // Fix this by adjusting to use the post-increment trip counter.
2670 Node *phi = cl->phi();
2671 if( !phi ) return; // Dead infinite loop
2672
2673 // Shape messed up, probably by iteration_split_impl
2674 if (phi->in(LoopNode::LoopBackControl) != cl->incr()) return;
2675
2676 bool progress = true;
2677 while (progress) {
2678 progress = false;
2679 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
2680 Node* use = phi->fast_out(i); // User of trip-counter
2681 if (!has_ctrl(use)) continue;
2682 Node *u_ctrl = get_ctrl(use);
2683 if( use->is_Phi() ) {
2684 u_ctrl = NULL;
2685 for( uint j = 1; j < use->req(); j++ )
2686 if( use->in(j) == phi )
2687 u_ctrl = dom_lca( u_ctrl, use->in(0)->in(j) );
2688 }
2689 IdealLoopTree *u_loop = get_loop(u_ctrl);
2690 // Look for loop-invariant use
2691 if( u_loop == loop ) continue;
2692 if( loop->is_member( u_loop ) ) continue;
2693 // Check that use is live out the bottom. Assuming the trip-counter
2694 // update is right at the bottom, uses of of the loop middle are ok.
2695 if( dom_lca( exit, u_ctrl ) != exit ) continue;
2696 // protect against stride not being a constant
2697 if( !cle->stride_is_con() ) continue;
2698 // Hit! Refactor use to use the post-incremented tripcounter.
2699 // Compute a post-increment tripcounter.
2700 Node *opaq = new (C, 2) Opaque2Node( C, cle->incr() );
2701 register_new_node( opaq, u_ctrl );
2702 Node *neg_stride = _igvn.intcon(-cle->stride_con());
2703 set_ctrl(neg_stride, C->root());
2704 Node *post = new (C, 3) AddINode( opaq, neg_stride);
2705 register_new_node( post, u_ctrl );
2706 _igvn.hash_delete(use);
2707 _igvn._worklist.push(use);
2708 for( uint j = 1; j < use->req(); j++ )
2709 if( use->in(j) == phi )
2710 use->set_req(j, post);
2711 // Since DU info changed, rerun loop
2712 progress = true;
2713 break;
2714 }
2715 }
2716
2717 }