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