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