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