1 /*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/connode.hpp"
29 #include "opto/divnode.hpp"
30 #include "opto/loopnode.hpp"
31 #include "opto/matcher.hpp"
32 #include "opto/mulnode.hpp"
33 #include "opto/movenode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37
38 //=============================================================================
39 //------------------------------split_thru_phi---------------------------------
40 // Split Node 'n' through merge point if there is enough win.
41 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
42 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
43 // ConvI2L may have type information on it which is unsafe to push up
44 // so disable this for now
45 return NULL;
46 }
47
48 int wins = 0;
49 assert(!n->is_CFG(), "");
50 assert(region->is_Region(), "");
51
52 const Type* type = n->bottom_type();
53 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
54 Node *phi;
55 if (t_oop != NULL && t_oop->is_known_instance_field()) {
56 int iid = t_oop->instance_id();
57 int index = C->get_alias_index(t_oop);
58 int offset = t_oop->offset();
59 phi = new PhiNode(region, type, NULL, iid, index, offset);
60 } else {
61 phi = PhiNode::make_blank(region, n);
62 }
63 uint old_unique = C->unique();
64 for (uint i = 1; i < region->req(); i++) {
65 Node *x;
66 Node* the_clone = NULL;
67 if (region->in(i) == C->top()) {
68 x = C->top(); // Dead path? Use a dead data op
69 } else {
70 x = n->clone(); // Else clone up the data op
71 the_clone = x; // Remember for possible deletion.
72 // Alter data node to use pre-phi inputs
73 if (n->in(0) == region)
74 x->set_req( 0, region->in(i) );
75 for (uint j = 1; j < n->req(); j++) {
76 Node *in = n->in(j);
77 if (in->is_Phi() && in->in(0) == region)
78 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
79 }
80 }
81 // Check for a 'win' on some paths
82 const Type *t = x->Value(&_igvn);
83
84 bool singleton = t->singleton();
85
86 // A TOP singleton indicates that there are no possible values incoming
87 // along a particular edge. In most cases, this is OK, and the Phi will
88 // be eliminated later in an Ideal call. However, we can't allow this to
89 // happen if the singleton occurs on loop entry, as the elimination of
90 // the PhiNode may cause the resulting node to migrate back to a previous
91 // loop iteration.
92 if (singleton && t == Type::TOP) {
93 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
94 // irreducible loop may not be indicated by an affirmative is_Loop());
95 // therefore, the only top we can split thru a phi is on a backedge of
96 // a loop.
97 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
98 }
99
100 if (singleton) {
101 wins++;
102 x = ((PhaseGVN&)_igvn).makecon(t);
103 } else {
104 // We now call Identity to try to simplify the cloned node.
105 // Note that some Identity methods call phase->type(this).
106 // Make sure that the type array is big enough for
107 // our new node, even though we may throw the node away.
108 // (Note: This tweaking with igvn only works because x is a new node.)
109 _igvn.set_type(x, t);
110 // If x is a TypeNode, capture any more-precise type permanently into Node
111 // otherwise it will be not updated during igvn->transform since
112 // igvn->type(x) is set to x->Value() already.
113 x->raise_bottom_type(t);
114 Node *y = x->Identity(&_igvn);
115 if (y != x) {
116 wins++;
117 x = y;
118 } else {
119 y = _igvn.hash_find(x);
120 if (y) {
121 wins++;
122 x = y;
123 } else {
124 // Else x is a new node we are keeping
125 // We do not need register_new_node_with_optimizer
126 // because set_type has already been called.
127 _igvn._worklist.push(x);
128 }
129 }
130 }
131 if (x != the_clone && the_clone != NULL)
132 _igvn.remove_dead_node(the_clone);
133 phi->set_req( i, x );
134 }
135 // Too few wins?
136 if (wins <= policy) {
137 _igvn.remove_dead_node(phi);
138 return NULL;
139 }
140
141 // Record Phi
142 register_new_node( phi, region );
143
144 for (uint i2 = 1; i2 < phi->req(); i2++) {
145 Node *x = phi->in(i2);
146 // If we commoned up the cloned 'x' with another existing Node,
147 // the existing Node picks up a new use. We need to make the
148 // existing Node occur higher up so it dominates its uses.
149 Node *old_ctrl;
150 IdealLoopTree *old_loop;
151
152 if (x->is_Con()) {
153 // Constant's control is always root.
154 set_ctrl(x, C->root());
155 continue;
156 }
157 // The occasional new node
158 if (x->_idx >= old_unique) { // Found a new, unplaced node?
159 old_ctrl = NULL;
160 old_loop = NULL; // Not in any prior loop
161 } else {
162 old_ctrl = get_ctrl(x);
163 old_loop = get_loop(old_ctrl); // Get prior loop
164 }
165 // New late point must dominate new use
166 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
167 if (new_ctrl == old_ctrl) // Nothing is changed
168 continue;
169
170 IdealLoopTree *new_loop = get_loop(new_ctrl);
171
172 // Don't move x into a loop if its uses are
173 // outside of loop. Otherwise x will be cloned
174 // for each use outside of this loop.
175 IdealLoopTree *use_loop = get_loop(region);
176 if (!new_loop->is_member(use_loop) &&
177 (old_loop == NULL || !new_loop->is_member(old_loop))) {
178 // Take early control, later control will be recalculated
179 // during next iteration of loop optimizations.
180 new_ctrl = get_early_ctrl(x);
181 new_loop = get_loop(new_ctrl);
182 }
183 // Set new location
184 set_ctrl(x, new_ctrl);
185 // If changing loop bodies, see if we need to collect into new body
186 if (old_loop != new_loop) {
187 if (old_loop && !old_loop->_child)
188 old_loop->_body.yank(x);
189 if (!new_loop->_child)
190 new_loop->_body.push(x); // Collect body info
191 }
192 }
193
194 return phi;
195 }
196
197 //------------------------------dominated_by------------------------------------
198 // Replace the dominated test with an obvious true or false. Place it on the
199 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
200 // live path up to the dominating control.
201 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
202 #ifndef PRODUCT
203 if (VerifyLoopOptimizations && PrintOpto) tty->print_cr("dominating test");
204 #endif
205
206
207 // prevdom is the dominating projection of the dominating test.
208 assert( iff->is_If(), "" );
209 assert( iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
210 int pop = prevdom->Opcode();
211 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
212 if (flip) {
213 if (pop == Op_IfTrue)
214 pop = Op_IfFalse;
215 else
216 pop = Op_IfTrue;
217 }
218 // 'con' is set to true or false to kill the dominated test.
219 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
220 set_ctrl(con, C->root()); // Constant gets a new use
221 // Hack the dominated test
222 _igvn.replace_input_of(iff, 1, con);
223
224 // If I dont have a reachable TRUE and FALSE path following the IfNode then
225 // I can assume this path reaches an infinite loop. In this case it's not
226 // important to optimize the data Nodes - either the whole compilation will
227 // be tossed or this path (and all data Nodes) will go dead.
228 if (iff->outcnt() != 2) return;
229
230 // Make control-dependent data Nodes on the live path (path that will remain
231 // once the dominated IF is removed) become control-dependent on the
232 // dominating projection.
233 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
234
235 // Loop predicates may have depending checks which should not
236 // be skipped. For example, range check predicate has two checks
237 // for lower and upper bounds.
238 if (dp == NULL)
239 return;
240
241 ProjNode* dp_proj = dp->as_Proj();
242 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
243 if (exclude_loop_predicate &&
244 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate))
245 return; // Let IGVN transformation change control dependence.
246
247 IdealLoopTree *old_loop = get_loop(dp);
248
249 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
250 Node* cd = dp->fast_out(i); // Control-dependent node
251 if (cd->depends_only_on_test()) {
252 assert(cd->in(0) == dp, "");
253 _igvn.replace_input_of(cd, 0, prevdom);
254 set_early_ctrl(cd);
255 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
256 if (old_loop != new_loop) {
257 if (!old_loop->_child) old_loop->_body.yank(cd);
258 if (!new_loop->_child) new_loop->_body.push(cd);
259 }
260 --i;
261 --imax;
262 }
263 }
264 }
265
266 //------------------------------has_local_phi_input----------------------------
267 // Return TRUE if 'n' has Phi inputs from its local block and no other
268 // block-local inputs (all non-local-phi inputs come from earlier blocks)
269 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
270 Node *n_ctrl = get_ctrl(n);
271 // See if some inputs come from a Phi in this block, or from before
272 // this block.
273 uint i;
274 for( i = 1; i < n->req(); i++ ) {
275 Node *phi = n->in(i);
276 if( phi->is_Phi() && phi->in(0) == n_ctrl )
277 break;
278 }
279 if( i >= n->req() )
280 return NULL; // No Phi inputs; nowhere to clone thru
281
282 // Check for inputs created between 'n' and the Phi input. These
283 // must split as well; they have already been given the chance
284 // (courtesy of a post-order visit) and since they did not we must
285 // recover the 'cost' of splitting them by being very profitable
286 // when splitting 'n'. Since this is unlikely we simply give up.
287 for( i = 1; i < n->req(); i++ ) {
288 Node *m = n->in(i);
289 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
290 // We allow the special case of AddP's with no local inputs.
291 // This allows us to split-up address expressions.
292 if (m->is_AddP() &&
293 get_ctrl(m->in(2)) != n_ctrl &&
294 get_ctrl(m->in(3)) != n_ctrl) {
295 // Move the AddP up to dominating point
296 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
297 continue;
298 }
299 return NULL;
300 }
301 }
302
303 return n_ctrl;
304 }
305
306 //------------------------------remix_address_expressions----------------------
307 // Rework addressing expressions to get the most loop-invariant stuff
308 // moved out. We'd like to do all associative operators, but it's especially
309 // important (common) to do address expressions.
310 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
311 if (!has_ctrl(n)) return NULL;
312 Node *n_ctrl = get_ctrl(n);
313 IdealLoopTree *n_loop = get_loop(n_ctrl);
314
315 // See if 'n' mixes loop-varying and loop-invariant inputs and
316 // itself is loop-varying.
317
318 // Only interested in binary ops (and AddP)
319 if( n->req() < 3 || n->req() > 4 ) return NULL;
320
321 Node *n1_ctrl = get_ctrl(n->in( 1));
322 Node *n2_ctrl = get_ctrl(n->in( 2));
323 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
324 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
325 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
326 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
327
328 // Does one of my inputs spin in a tighter loop than self?
329 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
330 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
331 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
332 return NULL; // Leave well enough alone
333
334 // Is at least one of my inputs loop-invariant?
335 if( n1_loop == n_loop &&
336 n2_loop == n_loop &&
337 n3_loop == n_loop )
338 return NULL; // No loop-invariant inputs
339
340
341 int n_op = n->Opcode();
342
343 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
344 if( n_op == Op_LShiftI ) {
345 // Scale is loop invariant
346 Node *scale = n->in(2);
347 Node *scale_ctrl = get_ctrl(scale);
348 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
349 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
350 return NULL;
351 const TypeInt *scale_t = scale->bottom_type()->isa_int();
352 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
353 return NULL; // Dont bother with byte/short masking
354 // Add must vary with loop (else shift would be loop-invariant)
355 Node *add = n->in(1);
356 Node *add_ctrl = get_ctrl(add);
357 IdealLoopTree *add_loop = get_loop(add_ctrl);
358 //assert( n_loop == add_loop, "" );
359 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
360
361 // Convert I-V into I+ (0-V); same for V-I
362 if( add->Opcode() == Op_SubI &&
363 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
364 Node *zero = _igvn.intcon(0);
365 set_ctrl(zero, C->root());
366 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
367 register_new_node( neg, get_ctrl(add->in(2) ) );
368 add = new AddINode( add->in(1), neg );
369 register_new_node( add, add_ctrl );
370 }
371 if( add->Opcode() != Op_AddI ) return NULL;
372 // See if one add input is loop invariant
373 Node *add_var = add->in(1);
374 Node *add_var_ctrl = get_ctrl(add_var);
375 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
376 Node *add_invar = add->in(2);
377 Node *add_invar_ctrl = get_ctrl(add_invar);
378 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
379 if( add_var_loop == n_loop ) {
380 } else if( add_invar_loop == n_loop ) {
381 // Swap to find the invariant part
382 add_invar = add_var;
383 add_invar_ctrl = add_var_ctrl;
384 add_invar_loop = add_var_loop;
385 add_var = add->in(2);
386 Node *add_var_ctrl = get_ctrl(add_var);
387 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
388 } else // Else neither input is loop invariant
389 return NULL;
390 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
391 return NULL; // No invariant part of the add?
392
393 // Yes! Reshape address expression!
394 Node *inv_scale = new LShiftINode( add_invar, scale );
395 Node *inv_scale_ctrl =
396 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
397 add_invar_ctrl : scale_ctrl;
398 register_new_node( inv_scale, inv_scale_ctrl );
399 Node *var_scale = new LShiftINode( add_var, scale );
400 register_new_node( var_scale, n_ctrl );
401 Node *var_add = new AddINode( var_scale, inv_scale );
402 register_new_node( var_add, n_ctrl );
403 _igvn.replace_node( n, var_add );
404 return var_add;
405 }
406
407 // Replace (I+V) with (V+I)
408 if( n_op == Op_AddI ||
409 n_op == Op_AddL ||
410 n_op == Op_AddF ||
411 n_op == Op_AddD ||
412 n_op == Op_MulI ||
413 n_op == Op_MulL ||
414 n_op == Op_MulF ||
415 n_op == Op_MulD ) {
416 if( n2_loop == n_loop ) {
417 assert( n1_loop != n_loop, "" );
418 n->swap_edges(1, 2);
419 }
420 }
421
422 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
423 // but not if I2 is a constant.
424 if( n_op == Op_AddP ) {
425 if( n2_loop == n_loop && n3_loop != n_loop ) {
426 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
427 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
428 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
429 IdealLoopTree *n22loop = get_loop( n22_ctrl );
430 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
431 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
432 n23_loop == n_loop ) {
433 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
434 // Stuff new AddP in the loop preheader
435 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
436 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
437 register_new_node( add2, n_ctrl );
438 _igvn.replace_node( n, add2 );
439 return add2;
440 }
441 }
442 }
443
444 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
445 if( n2_loop != n_loop && n3_loop == n_loop ) {
446 if( n->in(3)->Opcode() == Op_AddI ) {
447 Node *V = n->in(3)->in(1);
448 Node *I = n->in(3)->in(2);
449 if( is_member(n_loop,get_ctrl(V)) ) {
450 } else {
451 Node *tmp = V; V = I; I = tmp;
452 }
453 if( !is_member(n_loop,get_ctrl(I)) ) {
454 Node *add1 = new AddPNode( n->in(1), n->in(2), I );
455 // Stuff new AddP in the loop preheader
456 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
457 Node *add2 = new AddPNode( n->in(1), add1, V );
458 register_new_node( add2, n_ctrl );
459 _igvn.replace_node( n, add2 );
460 return add2;
461 }
462 }
463 }
464 }
465
466 return NULL;
467 }
468
469 //------------------------------conditional_move-------------------------------
470 // Attempt to replace a Phi with a conditional move. We have some pretty
471 // strict profitability requirements. All Phis at the merge point must
472 // be converted, so we can remove the control flow. We need to limit the
473 // number of c-moves to a small handful. All code that was in the side-arms
474 // of the CFG diamond is now speculatively executed. This code has to be
475 // "cheap enough". We are pretty much limited to CFG diamonds that merge
476 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
477 Node *PhaseIdealLoop::conditional_move( Node *region ) {
478
479 assert(region->is_Region(), "sanity check");
480 if (region->req() != 3) return NULL;
481
482 // Check for CFG diamond
483 Node *lp = region->in(1);
484 Node *rp = region->in(2);
485 if (!lp || !rp) return NULL;
486 Node *lp_c = lp->in(0);
487 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
488 IfNode *iff = lp_c->as_If();
489
490 // Check for ops pinned in an arm of the diamond.
491 // Can't remove the control flow in this case
492 if (lp->outcnt() > 1) return NULL;
493 if (rp->outcnt() > 1) return NULL;
494
495 IdealLoopTree* r_loop = get_loop(region);
496 assert(r_loop == get_loop(iff), "sanity");
497 // Always convert to CMOVE if all results are used only outside this loop.
498 bool used_inside_loop = (r_loop == _ltree_root);
499
500 // Check profitability
501 int cost = 0;
502 int phis = 0;
503 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
504 Node *out = region->fast_out(i);
505 if (!out->is_Phi()) continue; // Ignore other control edges, etc
506 phis++;
507 PhiNode* phi = out->as_Phi();
508 BasicType bt = phi->type()->basic_type();
509 switch (bt) {
510 case T_FLOAT:
511 case T_DOUBLE: {
512 cost += Matcher::float_cmove_cost(); // Could be very expensive
513 break;
514 }
515 case T_LONG: {
516 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
517 }
518 case T_INT: // These all CMOV fine
519 case T_ADDRESS: { // (RawPtr)
520 cost++;
521 break;
522 }
523 case T_NARROWOOP: // Fall through
524 case T_OBJECT: { // Base oops are OK, but not derived oops
525 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
526 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
527 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
528 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
529 // have a Phi for the base here that we convert to a CMOVE all is well
530 // and good. But if the base is dead, we'll not make a CMOVE. Later
531 // the allocator will have to produce a base by creating a CMOVE of the
532 // relevant bases. This puts the allocator in the business of
533 // manufacturing expensive instructions, generally a bad plan.
534 // Just Say No to Conditionally-Moved Derived Pointers.
535 if (tp && tp->offset() != 0)
536 return NULL;
537 cost++;
538 break;
539 }
540 default:
541 return NULL; // In particular, can't do memory or I/O
542 }
543 // Add in cost any speculative ops
544 for (uint j = 1; j < region->req(); j++) {
545 Node *proj = region->in(j);
546 Node *inp = phi->in(j);
547 if (get_ctrl(inp) == proj) { // Found local op
548 cost++;
549 // Check for a chain of dependent ops; these will all become
550 // speculative in a CMOV.
551 for (uint k = 1; k < inp->req(); k++)
552 if (get_ctrl(inp->in(k)) == proj)
553 cost += ConditionalMoveLimit; // Too much speculative goo
554 }
555 }
556 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
557 // This will likely Split-If, a higher-payoff operation.
558 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
559 Node* use = phi->fast_out(k);
560 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
561 cost += ConditionalMoveLimit;
562 // Is there a use inside the loop?
563 // Note: check only basic types since CMoveP is pinned.
564 if (!used_inside_loop && is_java_primitive(bt)) {
565 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
566 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
567 used_inside_loop = true;
568 }
569 }
570 }
571 }
572 Node* bol = iff->in(1);
573 assert(bol->Opcode() == Op_Bool, "");
574 int cmp_op = bol->in(1)->Opcode();
575 // It is expensive to generate flags from a float compare.
576 // Avoid duplicated float compare.
577 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
578
579 float infrequent_prob = PROB_UNLIKELY_MAG(3);
580 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
581 if (used_inside_loop) {
582 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
583
584 // BlockLayoutByFrequency optimization moves infrequent branch
585 // from hot path. No point in CMOV'ing in such case (110 is used
586 // instead of 100 to take into account not exactness of float value).
587 if (BlockLayoutByFrequency) {
588 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
589 }
590 }
591 // Check for highly predictable branch. No point in CMOV'ing if
592 // we are going to predict accurately all the time.
593 if (iff->_prob < infrequent_prob ||
594 iff->_prob > (1.0f - infrequent_prob))
595 return NULL;
596
597 // --------------
598 // Now replace all Phis with CMOV's
599 Node *cmov_ctrl = iff->in(0);
600 uint flip = (lp->Opcode() == Op_IfTrue);
601 while (1) {
602 PhiNode* phi = NULL;
603 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
604 Node *out = region->fast_out(i);
605 if (out->is_Phi()) {
606 phi = out->as_Phi();
607 break;
608 }
609 }
610 if (phi == NULL) break;
611 #ifndef PRODUCT
612 if (PrintOpto && VerifyLoopOptimizations) tty->print_cr("CMOV");
613 #endif
614 // Move speculative ops
615 for (uint j = 1; j < region->req(); j++) {
616 Node *proj = region->in(j);
617 Node *inp = phi->in(j);
618 if (get_ctrl(inp) == proj) { // Found local op
619 #ifndef PRODUCT
620 if (PrintOpto && VerifyLoopOptimizations) {
621 tty->print(" speculate: ");
622 inp->dump();
623 }
624 #endif
625 set_ctrl(inp, cmov_ctrl);
626 }
627 }
628 Node *cmov = CMoveNode::make( C, cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi) );
629 register_new_node( cmov, cmov_ctrl );
630 _igvn.replace_node( phi, cmov );
631 #ifndef PRODUCT
632 if (TraceLoopOpts) {
633 tty->print("CMOV ");
634 r_loop->dump_head();
635 if (Verbose) {
636 bol->in(1)->dump(1);
637 cmov->dump(1);
638 }
639 }
640 if (VerifyLoopOptimizations) verify();
641 #endif
642 }
643
644 // The useless CFG diamond will fold up later; see the optimization in
645 // RegionNode::Ideal.
646 _igvn._worklist.push(region);
647
648 return iff->in(1);
649 }
650
651 //------------------------------split_if_with_blocks_pre-----------------------
652 // Do the real work in a non-recursive function. Data nodes want to be
653 // cloned in the pre-order so they can feed each other nicely.
654 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
655 // Cloning these guys is unlikely to win
656 int n_op = n->Opcode();
657 if( n_op == Op_MergeMem ) return n;
658 if( n->is_Proj() ) return n;
659 // Do not clone-up CmpFXXX variations, as these are always
660 // followed by a CmpI
661 if( n->is_Cmp() ) return n;
662 // Attempt to use a conditional move instead of a phi/branch
663 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
664 Node *cmov = conditional_move( n );
665 if( cmov ) return cmov;
666 }
667 if( n->is_CFG() || n->is_LoadStore() )
668 return n;
669 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
670 n_op == Op_Opaque2 ) {
671 if( !C->major_progress() ) // If chance of no more loop opts...
672 _igvn._worklist.push(n); // maybe we'll remove them
673 return n;
674 }
675
676 if( n->is_Con() ) return n; // No cloning for Con nodes
677
678 Node *n_ctrl = get_ctrl(n);
679 if( !n_ctrl ) return n; // Dead node
680
681 // Attempt to remix address expressions for loop invariants
682 Node *m = remix_address_expressions( n );
683 if( m ) return m;
684
685 // Determine if the Node has inputs from some local Phi.
686 // Returns the block to clone thru.
687 Node *n_blk = has_local_phi_input( n );
688 if( !n_blk ) return n;
689 // Do not clone the trip counter through on a CountedLoop
690 // (messes up the canonical shape).
691 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
692
693 // Check for having no control input; not pinned. Allow
694 // dominating control.
695 if( n->in(0) ) {
696 Node *dom = idom(n_blk);
697 if( dom_lca( n->in(0), dom ) != n->in(0) )
698 return n;
699 }
700 // Policy: when is it profitable. You must get more wins than
701 // policy before it is considered profitable. Policy is usually 0,
702 // so 1 win is considered profitable. Big merges will require big
703 // cloning, so get a larger policy.
704 int policy = n_blk->req() >> 2;
705
706 // If the loop is a candidate for range check elimination,
707 // delay splitting through it's phi until a later loop optimization
708 if (n_blk->is_CountedLoop()) {
709 IdealLoopTree *lp = get_loop(n_blk);
710 if (lp && lp->_rce_candidate) {
711 return n;
712 }
713 }
714
715 // Use same limit as split_if_with_blocks_post
716 if( C->unique() > 35000 ) return n; // Method too big
717
718 // Split 'n' through the merge point if it is profitable
719 Node *phi = split_thru_phi( n, n_blk, policy );
720 if (!phi) return n;
721
722 // Found a Phi to split thru!
723 // Replace 'n' with the new phi
724 _igvn.replace_node( n, phi );
725 // Moved a load around the loop, 'en-registering' something.
726 if (n_blk->is_Loop() && n->is_Load() &&
727 !phi->in(LoopNode::LoopBackControl)->is_Load())
728 C->set_major_progress();
729
730 return phi;
731 }
732
733 static bool merge_point_too_heavy(Compile* C, Node* region) {
734 // Bail out if the region and its phis have too many users.
735 int weight = 0;
736 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
737 weight += region->fast_out(i)->outcnt();
738 }
739 int nodes_left = MaxNodeLimit - C->live_nodes();
740 if (weight * 8 > nodes_left) {
741 #ifndef PRODUCT
742 if (PrintOpto)
743 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
744 #endif
745 return true;
746 } else {
747 return false;
748 }
749 }
750
751 static bool merge_point_safe(Node* region) {
752 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
753 // having a PhiNode input. This sidesteps the dangerous case where the split
754 // ConvI2LNode may become TOP if the input Value() does not
755 // overlap the ConvI2L range, leaving a node which may not dominate its
756 // uses.
757 // A better fix for this problem can be found in the BugTraq entry, but
758 // expediency for Mantis demands this hack.
759 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
760 // split_if_with_blocks from splitting a block because we could not move around
761 // the FastLockNode.
762 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
763 Node* n = region->fast_out(i);
764 if (n->is_Phi()) {
765 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
766 Node* m = n->fast_out(j);
767 if (m->is_FastLock())
768 return false;
769 #ifdef _LP64
770 if (m->Opcode() == Op_ConvI2L)
771 return false;
772 #endif
773 }
774 }
775 }
776 return true;
777 }
778
779
780 //------------------------------place_near_use---------------------------------
781 // Place some computation next to use but not inside inner loops.
782 // For inner loop uses move it to the preheader area.
783 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
784 IdealLoopTree *u_loop = get_loop( useblock );
785 return (u_loop->_irreducible || u_loop->_child)
786 ? useblock
787 : u_loop->_head->in(LoopNode::EntryControl);
788 }
789
790
791 //------------------------------split_if_with_blocks_post----------------------
792 // Do the real work in a non-recursive function. CFG hackery wants to be
793 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
794 // info.
795 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
796
797 // Cloning Cmp through Phi's involves the split-if transform.
798 // FastLock is not used by an If
799 if( n->is_Cmp() && !n->is_FastLock() ) {
800 if( C->unique() > 35000 ) return; // Method too big
801
802 // Do not do 'split-if' if irreducible loops are present.
803 if( _has_irreducible_loops )
804 return;
805
806 Node *n_ctrl = get_ctrl(n);
807 // Determine if the Node has inputs from some local Phi.
808 // Returns the block to clone thru.
809 Node *n_blk = has_local_phi_input( n );
810 if( n_blk != n_ctrl ) return;
811
812 if( merge_point_too_heavy(C, n_ctrl) )
813 return;
814
815 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
816 Node *bol = n->unique_out();
817 assert( bol->is_Bool(), "expect a bool here" );
818 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
819 Node *iff = bol->unique_out();
820
821 // Check some safety conditions
822 if( iff->is_If() ) { // Classic split-if?
823 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
824 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
825 // Can't split CMove with different control edge.
826 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
827 if( get_ctrl(iff->in(2)) == n_ctrl ||
828 get_ctrl(iff->in(3)) == n_ctrl )
829 return; // Inputs not yet split-up
830 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
831 return; // Loop-invar test gates loop-varying CMOVE
832 }
833 } else {
834 return; // some other kind of node, such as an Allocate
835 }
836
837 // Do not do 'split-if' if some paths are dead. First do dead code
838 // elimination and then see if its still profitable.
839 for( uint i = 1; i < n_ctrl->req(); i++ )
840 if( n_ctrl->in(i) == C->top() )
841 return;
842
843 // When is split-if profitable? Every 'win' on means some control flow
844 // goes dead, so it's almost always a win.
845 int policy = 0;
846 // If trying to do a 'Split-If' at the loop head, it is only
847 // profitable if the cmp folds up on BOTH paths. Otherwise we
848 // risk peeling a loop forever.
849
850 // CNC - Disabled for now. Requires careful handling of loop
851 // body selection for the cloned code. Also, make sure we check
852 // for any input path not being in the same loop as n_ctrl. For
853 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
854 // because the alternative loop entry points won't be converted
855 // into LoopNodes.
856 IdealLoopTree *n_loop = get_loop(n_ctrl);
857 for( uint j = 1; j < n_ctrl->req(); j++ )
858 if( get_loop(n_ctrl->in(j)) != n_loop )
859 return;
860
861 // Check for safety of the merge point.
862 if( !merge_point_safe(n_ctrl) ) {
863 return;
864 }
865
866 // Split compare 'n' through the merge point if it is profitable
867 Node *phi = split_thru_phi( n, n_ctrl, policy );
868 if( !phi ) return;
869
870 // Found a Phi to split thru!
871 // Replace 'n' with the new phi
872 _igvn.replace_node( n, phi );
873
874 // Now split the bool up thru the phi
875 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
876 guarantee(bolphi != NULL, "null boolean phi node");
877
878 _igvn.replace_node( bol, bolphi );
879 assert( iff->in(1) == bolphi, "" );
880
881 if( bolphi->Value(&_igvn)->singleton() )
882 return;
883
884 // Conditional-move? Must split up now
885 if( !iff->is_If() ) {
886 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
887 _igvn.replace_node( iff, cmovphi );
888 return;
889 }
890
891 // Now split the IF
892 do_split_if( iff );
893 return;
894 }
895
896 // Check for an IF ready to split; one that has its
897 // condition codes input coming from a Phi at the block start.
898 int n_op = n->Opcode();
899
900 // Check for an IF being dominated by another IF same test
901 if( n_op == Op_If ) {
902 Node *bol = n->in(1);
903 uint max = bol->outcnt();
904 // Check for same test used more than once?
905 if( n_op == Op_If && max > 1 && bol->is_Bool() ) {
906 // Search up IDOMs to see if this IF is dominated.
907 Node *cutoff = get_ctrl(bol);
908
909 // Now search up IDOMs till cutoff, looking for a dominating test
910 Node *prevdom = n;
911 Node *dom = idom(prevdom);
912 while( dom != cutoff ) {
913 if( dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom ) {
914 // Replace the dominated test with an obvious true or false.
915 // Place it on the IGVN worklist for later cleanup.
916 C->set_major_progress();
917 dominated_by( prevdom, n, false, true );
918 #ifndef PRODUCT
919 if( VerifyLoopOptimizations ) verify();
920 #endif
921 return;
922 }
923 prevdom = dom;
924 dom = idom(prevdom);
925 }
926 }
927 }
928
929 // See if a shared loop-varying computation has no loop-varying uses.
930 // Happens if something is only used for JVM state in uncommon trap exits,
931 // like various versions of induction variable+offset. Clone the
932 // computation per usage to allow it to sink out of the loop.
933 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
934 Node *n_ctrl = get_ctrl(n);
935 IdealLoopTree *n_loop = get_loop(n_ctrl);
936 if( n_loop != _ltree_root ) {
937 DUIterator_Fast imax, i = n->fast_outs(imax);
938 for (; i < imax; i++) {
939 Node* u = n->fast_out(i);
940 if( !has_ctrl(u) ) break; // Found control user
941 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
942 if( u_loop == n_loop ) break; // Found loop-varying use
943 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
944 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
945 }
946 bool did_break = (i < imax); // Did we break out of the previous loop?
947 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
948 Node *late_load_ctrl = NULL;
949 if (n->is_Load()) {
950 // If n is a load, get and save the result from get_late_ctrl(),
951 // to be later used in calculating the control for n's clones.
952 clear_dom_lca_tags();
953 late_load_ctrl = get_late_ctrl(n, n_ctrl);
954 }
955 // If n is a load, and the late control is the same as the current
956 // control, then the cloning of n is a pointless exercise, because
957 // GVN will ensure that we end up where we started.
958 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
959 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
960 Node *u = n->last_out(j); // Clone private computation per use
961 _igvn.rehash_node_delayed(u);
962 Node *x = n->clone(); // Clone computation
963 Node *x_ctrl = NULL;
964 if( u->is_Phi() ) {
965 // Replace all uses of normal nodes. Replace Phi uses
966 // individually, so the separate Nodes can sink down
967 // different paths.
968 uint k = 1;
969 while( u->in(k) != n ) k++;
970 u->set_req( k, x );
971 // x goes next to Phi input path
972 x_ctrl = u->in(0)->in(k);
973 --j;
974 } else { // Normal use
975 // Replace all uses
976 for( uint k = 0; k < u->req(); k++ ) {
977 if( u->in(k) == n ) {
978 u->set_req( k, x );
979 --j;
980 }
981 }
982 x_ctrl = get_ctrl(u);
983 }
984
985 // Find control for 'x' next to use but not inside inner loops.
986 // For inner loop uses get the preheader area.
987 x_ctrl = place_near_use(x_ctrl);
988
989 if (n->is_Load()) {
990 // For loads, add a control edge to a CFG node outside of the loop
991 // to force them to not combine and return back inside the loop
992 // during GVN optimization (4641526).
993 //
994 // Because we are setting the actual control input, factor in
995 // the result from get_late_ctrl() so we respect any
996 // anti-dependences. (6233005).
997 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
998
999 // Don't allow the control input to be a CFG splitting node.
1000 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1001 // should only have IfTrueNode and IfFalseNode (4985384).
1002 x_ctrl = find_non_split_ctrl(x_ctrl);
1003 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1004
1005 x->set_req(0, x_ctrl);
1006 }
1007 register_new_node(x, x_ctrl);
1008
1009 // Some institutional knowledge is needed here: 'x' is
1010 // yanked because if the optimizer runs GVN on it all the
1011 // cloned x's will common up and undo this optimization and
1012 // be forced back in the loop. This is annoying because it
1013 // makes +VerifyOpto report false-positives on progress. I
1014 // tried setting control edges on the x's to force them to
1015 // not combine, but the matching gets worried when it tries
1016 // to fold a StoreP and an AddP together (as part of an
1017 // address expression) and the AddP and StoreP have
1018 // different controls.
1019 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1020 }
1021 _igvn.remove_dead_node(n);
1022 }
1023 }
1024 }
1025 }
1026
1027 // Check for Opaque2's who's loop has disappeared - who's input is in the
1028 // same loop nest as their output. Remove 'em, they are no longer useful.
1029 if( n_op == Op_Opaque2 &&
1030 n->in(1) != NULL &&
1031 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1032 _igvn.replace_node( n, n->in(1) );
1033 }
1034 }
1035
1036 //------------------------------split_if_with_blocks---------------------------
1037 // Check for aggressive application of 'split-if' optimization,
1038 // using basic block level info.
1039 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1040 Node *n = C->root();
1041 visited.set(n->_idx); // first, mark node as visited
1042 // Do pre-visit work for root
1043 n = split_if_with_blocks_pre( n );
1044 uint cnt = n->outcnt();
1045 uint i = 0;
1046 while (true) {
1047 // Visit all children
1048 if (i < cnt) {
1049 Node* use = n->raw_out(i);
1050 ++i;
1051 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1052 // Now do pre-visit work for this use
1053 use = split_if_with_blocks_pre( use );
1054 nstack.push(n, i); // Save parent and next use's index.
1055 n = use; // Process all children of current use.
1056 cnt = use->outcnt();
1057 i = 0;
1058 }
1059 }
1060 else {
1061 // All of n's children have been processed, complete post-processing.
1062 if (cnt != 0 && !n->is_Con()) {
1063 assert(has_node(n), "no dead nodes");
1064 split_if_with_blocks_post( n );
1065 }
1066 if (nstack.is_empty()) {
1067 // Finished all nodes on stack.
1068 break;
1069 }
1070 // Get saved parent node and next use's index. Visit the rest of uses.
1071 n = nstack.node();
1072 cnt = n->outcnt();
1073 i = nstack.index();
1074 nstack.pop();
1075 }
1076 }
1077 }
1078
1079
1080 //=============================================================================
1081 //
1082 // C L O N E A L O O P B O D Y
1083 //
1084
1085 //------------------------------clone_iff--------------------------------------
1086 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1087 // "Nearly" because all Nodes have been cloned from the original in the loop,
1088 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1089 // through the Phi recursively, and return a Bool.
1090 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1091
1092 // Convert this Phi into a Phi merging Bools
1093 uint i;
1094 for( i = 1; i < phi->req(); i++ ) {
1095 Node *b = phi->in(i);
1096 if( b->is_Phi() ) {
1097 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1098 } else {
1099 assert( b->is_Bool(), "" );
1100 }
1101 }
1102
1103 Node *sample_bool = phi->in(1);
1104 Node *sample_cmp = sample_bool->in(1);
1105
1106 // Make Phis to merge the Cmp's inputs.
1107 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1108 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1109 for( i = 1; i < phi->req(); i++ ) {
1110 Node *n1 = phi->in(i)->in(1)->in(1);
1111 Node *n2 = phi->in(i)->in(1)->in(2);
1112 phi1->set_req( i, n1 );
1113 phi2->set_req( i, n2 );
1114 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1115 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1116 }
1117 // See if these Phis have been made before.
1118 // Register with optimizer
1119 Node *hit1 = _igvn.hash_find_insert(phi1);
1120 if( hit1 ) { // Hit, toss just made Phi
1121 _igvn.remove_dead_node(phi1); // Remove new phi
1122 assert( hit1->is_Phi(), "" );
1123 phi1 = (PhiNode*)hit1; // Use existing phi
1124 } else { // Miss
1125 _igvn.register_new_node_with_optimizer(phi1);
1126 }
1127 Node *hit2 = _igvn.hash_find_insert(phi2);
1128 if( hit2 ) { // Hit, toss just made Phi
1129 _igvn.remove_dead_node(phi2); // Remove new phi
1130 assert( hit2->is_Phi(), "" );
1131 phi2 = (PhiNode*)hit2; // Use existing phi
1132 } else { // Miss
1133 _igvn.register_new_node_with_optimizer(phi2);
1134 }
1135 // Register Phis with loop/block info
1136 set_ctrl(phi1, phi->in(0));
1137 set_ctrl(phi2, phi->in(0));
1138 // Make a new Cmp
1139 Node *cmp = sample_cmp->clone();
1140 cmp->set_req( 1, phi1 );
1141 cmp->set_req( 2, phi2 );
1142 _igvn.register_new_node_with_optimizer(cmp);
1143 set_ctrl(cmp, phi->in(0));
1144
1145 // Make a new Bool
1146 Node *b = sample_bool->clone();
1147 b->set_req(1,cmp);
1148 _igvn.register_new_node_with_optimizer(b);
1149 set_ctrl(b, phi->in(0));
1150
1151 assert( b->is_Bool(), "" );
1152 return (BoolNode*)b;
1153 }
1154
1155 //------------------------------clone_bool-------------------------------------
1156 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1157 // "Nearly" because all Nodes have been cloned from the original in the loop,
1158 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1159 // through the Phi recursively, and return a Bool.
1160 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1161 uint i;
1162 // Convert this Phi into a Phi merging Bools
1163 for( i = 1; i < phi->req(); i++ ) {
1164 Node *b = phi->in(i);
1165 if( b->is_Phi() ) {
1166 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1167 } else {
1168 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1169 }
1170 }
1171
1172 Node *sample_cmp = phi->in(1);
1173
1174 // Make Phis to merge the Cmp's inputs.
1175 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1176 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1177 for( uint j = 1; j < phi->req(); j++ ) {
1178 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1179 Node *n1, *n2;
1180 if( cmp_top->is_Cmp() ) {
1181 n1 = cmp_top->in(1);
1182 n2 = cmp_top->in(2);
1183 } else {
1184 n1 = n2 = cmp_top;
1185 }
1186 phi1->set_req( j, n1 );
1187 phi2->set_req( j, n2 );
1188 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1189 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1190 }
1191
1192 // See if these Phis have been made before.
1193 // Register with optimizer
1194 Node *hit1 = _igvn.hash_find_insert(phi1);
1195 if( hit1 ) { // Hit, toss just made Phi
1196 _igvn.remove_dead_node(phi1); // Remove new phi
1197 assert( hit1->is_Phi(), "" );
1198 phi1 = (PhiNode*)hit1; // Use existing phi
1199 } else { // Miss
1200 _igvn.register_new_node_with_optimizer(phi1);
1201 }
1202 Node *hit2 = _igvn.hash_find_insert(phi2);
1203 if( hit2 ) { // Hit, toss just made Phi
1204 _igvn.remove_dead_node(phi2); // Remove new phi
1205 assert( hit2->is_Phi(), "" );
1206 phi2 = (PhiNode*)hit2; // Use existing phi
1207 } else { // Miss
1208 _igvn.register_new_node_with_optimizer(phi2);
1209 }
1210 // Register Phis with loop/block info
1211 set_ctrl(phi1, phi->in(0));
1212 set_ctrl(phi2, phi->in(0));
1213 // Make a new Cmp
1214 Node *cmp = sample_cmp->clone();
1215 cmp->set_req( 1, phi1 );
1216 cmp->set_req( 2, phi2 );
1217 _igvn.register_new_node_with_optimizer(cmp);
1218 set_ctrl(cmp, phi->in(0));
1219
1220 assert( cmp->is_Cmp(), "" );
1221 return (CmpNode*)cmp;
1222 }
1223
1224 //------------------------------sink_use---------------------------------------
1225 // If 'use' was in the loop-exit block, it now needs to be sunk
1226 // below the post-loop merge point.
1227 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1228 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1229 set_ctrl(use, post_loop);
1230 for (DUIterator j = use->outs(); use->has_out(j); j++)
1231 sink_use(use->out(j), post_loop);
1232 }
1233 }
1234
1235 //------------------------------clone_loop-------------------------------------
1236 //
1237 // C L O N E A L O O P B O D Y
1238 //
1239 // This is the basic building block of the loop optimizations. It clones an
1240 // entire loop body. It makes an old_new loop body mapping; with this mapping
1241 // you can find the new-loop equivalent to an old-loop node. All new-loop
1242 // nodes are exactly equal to their old-loop counterparts, all edges are the
1243 // same. All exits from the old-loop now have a RegionNode that merges the
1244 // equivalent new-loop path. This is true even for the normal "loop-exit"
1245 // condition. All uses of loop-invariant old-loop values now come from (one
1246 // or more) Phis that merge their new-loop equivalents.
1247 //
1248 // This operation leaves the graph in an illegal state: there are two valid
1249 // control edges coming from the loop pre-header to both loop bodies. I'll
1250 // definitely have to hack the graph after running this transform.
1251 //
1252 // From this building block I will further edit edges to perform loop peeling
1253 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1254 //
1255 // Parameter side_by_size_idom:
1256 // When side_by_size_idom is NULL, the dominator tree is constructed for
1257 // the clone loop to dominate the original. Used in construction of
1258 // pre-main-post loop sequence.
1259 // When nonnull, the clone and original are side-by-side, both are
1260 // dominated by the side_by_side_idom node. Used in construction of
1261 // unswitched loops.
1262 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1263 Node* side_by_side_idom) {
1264
1265 // Step 1: Clone the loop body. Make the old->new mapping.
1266 uint i;
1267 for( i = 0; i < loop->_body.size(); i++ ) {
1268 Node *old = loop->_body.at(i);
1269 Node *nnn = old->clone();
1270 old_new.map( old->_idx, nnn );
1271 _igvn.register_new_node_with_optimizer(nnn);
1272 }
1273
1274
1275 // Step 2: Fix the edges in the new body. If the old input is outside the
1276 // loop use it. If the old input is INside the loop, use the corresponding
1277 // new node instead.
1278 for( i = 0; i < loop->_body.size(); i++ ) {
1279 Node *old = loop->_body.at(i);
1280 Node *nnn = old_new[old->_idx];
1281 // Fix CFG/Loop controlling the new node
1282 if (has_ctrl(old)) {
1283 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1284 } else {
1285 set_loop(nnn, loop->_parent);
1286 if (old->outcnt() > 0) {
1287 set_idom( nnn, old_new[idom(old)->_idx], dd );
1288 }
1289 }
1290 // Correct edges to the new node
1291 for( uint j = 0; j < nnn->req(); j++ ) {
1292 Node *n = nnn->in(j);
1293 if( n ) {
1294 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1295 if( loop->is_member( old_in_loop ) )
1296 nnn->set_req(j, old_new[n->_idx]);
1297 }
1298 }
1299 _igvn.hash_find_insert(nnn);
1300 }
1301 Node *newhead = old_new[loop->_head->_idx];
1302 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1303
1304
1305 // Step 3: Now fix control uses. Loop varying control uses have already
1306 // been fixed up (as part of all input edges in Step 2). Loop invariant
1307 // control uses must be either an IfFalse or an IfTrue. Make a merge
1308 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1309 // refer to this.
1310 ResourceArea *area = Thread::current()->resource_area();
1311 Node_List worklist(area);
1312 uint new_counter = C->unique();
1313 for( i = 0; i < loop->_body.size(); i++ ) {
1314 Node* old = loop->_body.at(i);
1315 if( !old->is_CFG() ) continue;
1316 Node* nnn = old_new[old->_idx];
1317
1318 // Copy uses to a worklist, so I can munge the def-use info
1319 // with impunity.
1320 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1321 worklist.push(old->fast_out(j));
1322
1323 while( worklist.size() ) { // Visit all uses
1324 Node *use = worklist.pop();
1325 if (!has_node(use)) continue; // Ignore dead nodes
1326 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1327 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1328 // Both OLD and USE are CFG nodes here.
1329 assert( use->is_Proj(), "" );
1330
1331 // Clone the loop exit control projection
1332 Node *newuse = use->clone();
1333 newuse->set_req(0,nnn);
1334 _igvn.register_new_node_with_optimizer(newuse);
1335 set_loop(newuse, use_loop);
1336 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1337
1338 // We need a Region to merge the exit from the peeled body and the
1339 // exit from the old loop body.
1340 RegionNode *r = new RegionNode(3);
1341 // Map the old use to the new merge point
1342 old_new.map( use->_idx, r );
1343 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1344 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1345
1346 // The original user of 'use' uses 'r' instead.
1347 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1348 Node* useuse = use->last_out(l);
1349 _igvn.rehash_node_delayed(useuse);
1350 uint uses_found = 0;
1351 if( useuse->in(0) == use ) {
1352 useuse->set_req(0, r);
1353 uses_found++;
1354 if( useuse->is_CFG() ) {
1355 assert( dom_depth(useuse) > dd_r, "" );
1356 set_idom(useuse, r, dom_depth(useuse));
1357 }
1358 }
1359 for( uint k = 1; k < useuse->req(); k++ ) {
1360 if( useuse->in(k) == use ) {
1361 useuse->set_req(k, r);
1362 uses_found++;
1363 }
1364 }
1365 l -= uses_found; // we deleted 1 or more copies of this edge
1366 }
1367
1368 // Now finish up 'r'
1369 r->set_req( 1, newuse );
1370 r->set_req( 2, use );
1371 _igvn.register_new_node_with_optimizer(r);
1372 set_loop(r, use_loop);
1373 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1374 } // End of if a loop-exit test
1375 }
1376 }
1377
1378 // Step 4: If loop-invariant use is not control, it must be dominated by a
1379 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1380 // there if needed. Make a Phi there merging old and new used values.
1381 Node_List *split_if_set = NULL;
1382 Node_List *split_bool_set = NULL;
1383 Node_List *split_cex_set = NULL;
1384 for( i = 0; i < loop->_body.size(); i++ ) {
1385 Node* old = loop->_body.at(i);
1386 Node* nnn = old_new[old->_idx];
1387 // Copy uses to a worklist, so I can munge the def-use info
1388 // with impunity.
1389 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1390 worklist.push(old->fast_out(j));
1391
1392 while( worklist.size() ) {
1393 Node *use = worklist.pop();
1394 if (!has_node(use)) continue; // Ignore dead nodes
1395 if (use->in(0) == C->top()) continue;
1396 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1397 // Check for data-use outside of loop - at least one of OLD or USE
1398 // must not be a CFG node.
1399 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1400
1401 // If the Data use is an IF, that means we have an IF outside of the
1402 // loop that is switching on a condition that is set inside of the
1403 // loop. Happens if people set a loop-exit flag; then test the flag
1404 // in the loop to break the loop, then test is again outside of the
1405 // loop to determine which way the loop exited.
1406 if( use->is_If() || use->is_CMove() ) {
1407 // Since this code is highly unlikely, we lazily build the worklist
1408 // of such Nodes to go split.
1409 if( !split_if_set )
1410 split_if_set = new Node_List(area);
1411 split_if_set->push(use);
1412 }
1413 if( use->is_Bool() ) {
1414 if( !split_bool_set )
1415 split_bool_set = new Node_List(area);
1416 split_bool_set->push(use);
1417 }
1418 if( use->Opcode() == Op_CreateEx ) {
1419 if( !split_cex_set )
1420 split_cex_set = new Node_List(area);
1421 split_cex_set->push(use);
1422 }
1423
1424
1425 // Get "block" use is in
1426 uint idx = 0;
1427 while( use->in(idx) != old ) idx++;
1428 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1429 assert( !loop->is_member( get_loop( prev ) ), "" );
1430 Node *cfg = prev->_idx >= new_counter
1431 ? prev->in(2)
1432 : idom(prev);
1433 if( use->is_Phi() ) // Phi use is in prior block
1434 cfg = prev->in(idx); // NOT in block of Phi itself
1435 if (cfg->is_top()) { // Use is dead?
1436 _igvn.replace_input_of(use, idx, C->top());
1437 continue;
1438 }
1439
1440 while( !loop->is_member( get_loop( cfg ) ) ) {
1441 prev = cfg;
1442 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1443 }
1444 // If the use occurs after merging several exits from the loop, then
1445 // old value must have dominated all those exits. Since the same old
1446 // value was used on all those exits we did not need a Phi at this
1447 // merge point. NOW we do need a Phi here. Each loop exit value
1448 // is now merged with the peeled body exit; each exit gets its own
1449 // private Phi and those Phis need to be merged here.
1450 Node *phi;
1451 if( prev->is_Region() ) {
1452 if( idx == 0 ) { // Updating control edge?
1453 phi = prev; // Just use existing control
1454 } else { // Else need a new Phi
1455 phi = PhiNode::make( prev, old );
1456 // Now recursively fix up the new uses of old!
1457 for( uint i = 1; i < prev->req(); i++ ) {
1458 worklist.push(phi); // Onto worklist once for each 'old' input
1459 }
1460 }
1461 } else {
1462 // Get new RegionNode merging old and new loop exits
1463 prev = old_new[prev->_idx];
1464 assert( prev, "just made this in step 7" );
1465 if( idx == 0 ) { // Updating control edge?
1466 phi = prev; // Just use existing control
1467 } else { // Else need a new Phi
1468 // Make a new Phi merging data values properly
1469 phi = PhiNode::make( prev, old );
1470 phi->set_req( 1, nnn );
1471 }
1472 }
1473 // If inserting a new Phi, check for prior hits
1474 if( idx != 0 ) {
1475 Node *hit = _igvn.hash_find_insert(phi);
1476 if( hit == NULL ) {
1477 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1478 } else { // or
1479 // Remove the new phi from the graph and use the hit
1480 _igvn.remove_dead_node(phi);
1481 phi = hit; // Use existing phi
1482 }
1483 set_ctrl(phi, prev);
1484 }
1485 // Make 'use' use the Phi instead of the old loop body exit value
1486 _igvn.replace_input_of(use, idx, phi);
1487 if( use->_idx >= new_counter ) { // If updating new phis
1488 // Not needed for correctness, but prevents a weak assert
1489 // in AddPNode from tripping (when we end up with different
1490 // base & derived Phis that will become the same after
1491 // IGVN does CSE).
1492 Node *hit = _igvn.hash_find_insert(use);
1493 if( hit ) // Go ahead and re-hash for hits.
1494 _igvn.replace_node( use, hit );
1495 }
1496
1497 // If 'use' was in the loop-exit block, it now needs to be sunk
1498 // below the post-loop merge point.
1499 sink_use( use, prev );
1500 }
1501 }
1502 }
1503
1504 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1505 // the loop uses a condition set in the loop. The original IF probably
1506 // takes control from one or more OLD Regions (which in turn get from NEW
1507 // Regions). In any case, there will be a set of Phis for each merge point
1508 // from the IF up to where the original BOOL def exists the loop.
1509 if( split_if_set ) {
1510 while( split_if_set->size() ) {
1511 Node *iff = split_if_set->pop();
1512 if( iff->in(1)->is_Phi() ) {
1513 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1514 _igvn.replace_input_of(iff, 1, b);
1515 }
1516 }
1517 }
1518 if( split_bool_set ) {
1519 while( split_bool_set->size() ) {
1520 Node *b = split_bool_set->pop();
1521 Node *phi = b->in(1);
1522 assert( phi->is_Phi(), "" );
1523 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1524 _igvn.replace_input_of(b, 1, cmp);
1525 }
1526 }
1527 if( split_cex_set ) {
1528 while( split_cex_set->size() ) {
1529 Node *b = split_cex_set->pop();
1530 assert( b->in(0)->is_Region(), "" );
1531 assert( b->in(1)->is_Phi(), "" );
1532 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1533 split_up( b, b->in(0), NULL );
1534 }
1535 }
1536
1537 }
1538
1539
1540 //---------------------- stride_of_possible_iv -------------------------------------
1541 // Looks for an iff/bool/comp with one operand of the compare
1542 // being a cycle involving an add and a phi,
1543 // with an optional truncation (left-shift followed by a right-shift)
1544 // of the add. Returns zero if not an iv.
1545 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1546 Node* trunc1 = NULL;
1547 Node* trunc2 = NULL;
1548 const TypeInt* ttype = NULL;
1549 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1550 return 0;
1551 }
1552 BoolNode* bl = iff->in(1)->as_Bool();
1553 Node* cmp = bl->in(1);
1554 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1555 return 0;
1556 }
1557 // Must have an invariant operand
1558 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1559 return 0;
1560 }
1561 Node* add2 = NULL;
1562 Node* cmp1 = cmp->in(1);
1563 if (cmp1->is_Phi()) {
1564 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1565 Node* phi = cmp1;
1566 for (uint i = 1; i < phi->req(); i++) {
1567 Node* in = phi->in(i);
1568 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1569 &trunc1, &trunc2, &ttype);
1570 if (add && add->in(1) == phi) {
1571 add2 = add->in(2);
1572 break;
1573 }
1574 }
1575 } else {
1576 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1577 Node* addtrunc = cmp1;
1578 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1579 &trunc1, &trunc2, &ttype);
1580 if (add && add->in(1)->is_Phi()) {
1581 Node* phi = add->in(1);
1582 for (uint i = 1; i < phi->req(); i++) {
1583 if (phi->in(i) == addtrunc) {
1584 add2 = add->in(2);
1585 break;
1586 }
1587 }
1588 }
1589 }
1590 if (add2 != NULL) {
1591 const TypeInt* add2t = _igvn.type(add2)->is_int();
1592 if (add2t->is_con()) {
1593 return add2t->get_con();
1594 }
1595 }
1596 return 0;
1597 }
1598
1599
1600 //---------------------- stay_in_loop -------------------------------------
1601 // Return the (unique) control output node that's in the loop (if it exists.)
1602 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1603 Node* unique = NULL;
1604 if (!n) return NULL;
1605 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1606 Node* use = n->fast_out(i);
1607 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1608 if (unique != NULL) {
1609 return NULL;
1610 }
1611 unique = use;
1612 }
1613 }
1614 return unique;
1615 }
1616
1617 //------------------------------ register_node -------------------------------------
1618 // Utility to register node "n" with PhaseIdealLoop
1619 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1620 _igvn.register_new_node_with_optimizer(n);
1621 loop->_body.push(n);
1622 if (n->is_CFG()) {
1623 set_loop(n, loop);
1624 set_idom(n, pred, ddepth);
1625 } else {
1626 set_ctrl(n, pred);
1627 }
1628 }
1629
1630 //------------------------------ proj_clone -------------------------------------
1631 // Utility to create an if-projection
1632 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1633 ProjNode* c = p->clone()->as_Proj();
1634 c->set_req(0, iff);
1635 return c;
1636 }
1637
1638 //------------------------------ short_circuit_if -------------------------------------
1639 // Force the iff control output to be the live_proj
1640 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1641 guarantee(live_proj != NULL, "null projection");
1642 int proj_con = live_proj->_con;
1643 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1644 Node *con = _igvn.intcon(proj_con);
1645 set_ctrl(con, C->root());
1646 if (iff) {
1647 iff->set_req(1, con);
1648 }
1649 return con;
1650 }
1651
1652 //------------------------------ insert_if_before_proj -------------------------------------
1653 // Insert a new if before an if projection (* - new node)
1654 //
1655 // before
1656 // if(test)
1657 // / \
1658 // v v
1659 // other-proj proj (arg)
1660 //
1661 // after
1662 // if(test)
1663 // / \
1664 // / v
1665 // | * proj-clone
1666 // v |
1667 // other-proj v
1668 // * new_if(relop(cmp[IU](left,right)))
1669 // / \
1670 // v v
1671 // * new-proj proj
1672 // (returned)
1673 //
1674 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1675 IfNode* iff = proj->in(0)->as_If();
1676 IdealLoopTree *loop = get_loop(proj);
1677 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1678 int ddepth = dom_depth(proj);
1679
1680 _igvn.rehash_node_delayed(iff);
1681 _igvn.rehash_node_delayed(proj);
1682
1683 proj->set_req(0, NULL); // temporary disconnect
1684 ProjNode* proj2 = proj_clone(proj, iff);
1685 register_node(proj2, loop, iff, ddepth);
1686
1687 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1688 register_node(cmp, loop, proj2, ddepth);
1689
1690 BoolNode* bol = new BoolNode(cmp, relop);
1691 register_node(bol, loop, proj2, ddepth);
1692
1693 IfNode* new_if = new IfNode(proj2, bol, iff->_prob, iff->_fcnt);
1694 register_node(new_if, loop, proj2, ddepth);
1695
1696 proj->set_req(0, new_if); // reattach
1697 set_idom(proj, new_if, ddepth);
1698
1699 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1700 guarantee(new_exit != NULL, "null exit node");
1701 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1702
1703 return new_exit;
1704 }
1705
1706 //------------------------------ insert_region_before_proj -------------------------------------
1707 // Insert a region before an if projection (* - new node)
1708 //
1709 // before
1710 // if(test)
1711 // / |
1712 // v |
1713 // proj v
1714 // other-proj
1715 //
1716 // after
1717 // if(test)
1718 // / |
1719 // v |
1720 // * proj-clone v
1721 // | other-proj
1722 // v
1723 // * new-region
1724 // |
1725 // v
1726 // * dum_if
1727 // / \
1728 // v \
1729 // * dum-proj v
1730 // proj
1731 //
1732 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
1733 IfNode* iff = proj->in(0)->as_If();
1734 IdealLoopTree *loop = get_loop(proj);
1735 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1736 int ddepth = dom_depth(proj);
1737
1738 _igvn.rehash_node_delayed(iff);
1739 _igvn.rehash_node_delayed(proj);
1740
1741 proj->set_req(0, NULL); // temporary disconnect
1742 ProjNode* proj2 = proj_clone(proj, iff);
1743 register_node(proj2, loop, iff, ddepth);
1744
1745 RegionNode* reg = new RegionNode(2);
1746 reg->set_req(1, proj2);
1747 register_node(reg, loop, iff, ddepth);
1748
1749 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
1750 register_node(dum_if, loop, reg, ddepth);
1751
1752 proj->set_req(0, dum_if); // reattach
1753 set_idom(proj, dum_if, ddepth);
1754
1755 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
1756 register_node(dum_proj, loop, dum_if, ddepth);
1757
1758 return reg;
1759 }
1760
1761 //------------------------------ insert_cmpi_loop_exit -------------------------------------
1762 // Clone a signed compare loop exit from an unsigned compare and
1763 // insert it before the unsigned cmp on the stay-in-loop path.
1764 // All new nodes inserted in the dominator tree between the original
1765 // if and it's projections. The original if test is replaced with
1766 // a constant to force the stay-in-loop path.
1767 //
1768 // This is done to make sure that the original if and it's projections
1769 // still dominate the same set of control nodes, that the ctrl() relation
1770 // from data nodes to them is preserved, and that their loop nesting is
1771 // preserved.
1772 //
1773 // before
1774 // if(i <u limit) unsigned compare loop exit
1775 // / |
1776 // v v
1777 // exit-proj stay-in-loop-proj
1778 //
1779 // after
1780 // if(stay-in-loop-const) original if
1781 // / |
1782 // / v
1783 // / if(i < limit) new signed test
1784 // / / |
1785 // / / v
1786 // / / if(i <u limit) new cloned unsigned test
1787 // / / / |
1788 // v v v |
1789 // region |
1790 // | |
1791 // dum-if |
1792 // / | |
1793 // ether | |
1794 // v v
1795 // exit-proj stay-in-loop-proj
1796 //
1797 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
1798 const bool Signed = true;
1799 const bool Unsigned = false;
1800
1801 BoolNode* bol = if_cmpu->in(1)->as_Bool();
1802 if (bol->_test._test != BoolTest::lt) return NULL;
1803 CmpNode* cmpu = bol->in(1)->as_Cmp();
1804 if (cmpu->Opcode() != Op_CmpU) return NULL;
1805 int stride = stride_of_possible_iv(if_cmpu);
1806 if (stride == 0) return NULL;
1807
1808 Node* lp_proj = stay_in_loop(if_cmpu, loop);
1809 guarantee(lp_proj != NULL, "null loop node");
1810
1811 ProjNode* lp_continue = lp_proj->as_Proj();
1812 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
1813
1814 Node* limit = NULL;
1815 if (stride > 0) {
1816 limit = cmpu->in(2);
1817 } else {
1818 limit = _igvn.makecon(TypeInt::ZERO);
1819 set_ctrl(limit, C->root());
1820 }
1821 // Create a new region on the exit path
1822 RegionNode* reg = insert_region_before_proj(lp_exit);
1823 guarantee(reg != NULL, "null region node");
1824
1825 // Clone the if-cmpu-true-false using a signed compare
1826 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
1827 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
1828 reg->add_req(cmpi_exit);
1829
1830 // Clone the if-cmpu-true-false
1831 BoolTest::mask rel_u = bol->_test._test;
1832 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
1833 reg->add_req(cmpu_exit);
1834
1835 // Force original if to stay in loop.
1836 short_circuit_if(if_cmpu, lp_continue);
1837
1838 return cmpi_exit->in(0)->as_If();
1839 }
1840
1841 //------------------------------ remove_cmpi_loop_exit -------------------------------------
1842 // Remove a previously inserted signed compare loop exit.
1843 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
1844 Node* lp_proj = stay_in_loop(if_cmp, loop);
1845 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
1846 stay_in_loop(lp_proj, loop)->is_If() &&
1847 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
1848 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
1849 set_ctrl(con, C->root());
1850 if_cmp->set_req(1, con);
1851 }
1852
1853 //------------------------------ scheduled_nodelist -------------------------------------
1854 // Create a post order schedule of nodes that are in the
1855 // "member" set. The list is returned in "sched".
1856 // The first node in "sched" is the loop head, followed by
1857 // nodes which have no inputs in the "member" set, and then
1858 // followed by the nodes that have an immediate input dependence
1859 // on a node in "sched".
1860 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
1861
1862 assert(member.test(loop->_head->_idx), "loop head must be in member set");
1863 Arena *a = Thread::current()->resource_area();
1864 VectorSet visited(a);
1865 Node_Stack nstack(a, loop->_body.size());
1866
1867 Node* n = loop->_head; // top of stack is cached in "n"
1868 uint idx = 0;
1869 visited.set(n->_idx);
1870
1871 // Initially push all with no inputs from within member set
1872 for(uint i = 0; i < loop->_body.size(); i++ ) {
1873 Node *elt = loop->_body.at(i);
1874 if (member.test(elt->_idx)) {
1875 bool found = false;
1876 for (uint j = 0; j < elt->req(); j++) {
1877 Node* def = elt->in(j);
1878 if (def && member.test(def->_idx) && def != elt) {
1879 found = true;
1880 break;
1881 }
1882 }
1883 if (!found && elt != loop->_head) {
1884 nstack.push(n, idx);
1885 n = elt;
1886 assert(!visited.test(n->_idx), "not seen yet");
1887 visited.set(n->_idx);
1888 }
1889 }
1890 }
1891
1892 // traverse out's that are in the member set
1893 while (true) {
1894 if (idx < n->outcnt()) {
1895 Node* use = n->raw_out(idx);
1896 idx++;
1897 if (!visited.test_set(use->_idx)) {
1898 if (member.test(use->_idx)) {
1899 nstack.push(n, idx);
1900 n = use;
1901 idx = 0;
1902 }
1903 }
1904 } else {
1905 // All outputs processed
1906 sched.push(n);
1907 if (nstack.is_empty()) break;
1908 n = nstack.node();
1909 idx = nstack.index();
1910 nstack.pop();
1911 }
1912 }
1913 }
1914
1915
1916 //------------------------------ has_use_in_set -------------------------------------
1917 // Has a use in the vector set
1918 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
1919 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1920 Node* use = n->fast_out(j);
1921 if (vset.test(use->_idx)) {
1922 return true;
1923 }
1924 }
1925 return false;
1926 }
1927
1928
1929 //------------------------------ has_use_internal_to_set -------------------------------------
1930 // Has use internal to the vector set (ie. not in a phi at the loop head)
1931 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
1932 Node* head = loop->_head;
1933 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1934 Node* use = n->fast_out(j);
1935 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
1936 return true;
1937 }
1938 }
1939 return false;
1940 }
1941
1942
1943 //------------------------------ clone_for_use_outside_loop -------------------------------------
1944 // clone "n" for uses that are outside of loop
1945 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
1946 int cloned = 0;
1947 assert(worklist.size() == 0, "should be empty");
1948 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1949 Node* use = n->fast_out(j);
1950 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
1951 worklist.push(use);
1952 }
1953 }
1954 while( worklist.size() ) {
1955 Node *use = worklist.pop();
1956 if (!has_node(use) || use->in(0) == C->top()) continue;
1957 uint j;
1958 for (j = 0; j < use->req(); j++) {
1959 if (use->in(j) == n) break;
1960 }
1961 assert(j < use->req(), "must be there");
1962
1963 // clone "n" and insert it between the inputs of "n" and the use outside the loop
1964 Node* n_clone = n->clone();
1965 _igvn.replace_input_of(use, j, n_clone);
1966 cloned++;
1967 Node* use_c;
1968 if (!use->is_Phi()) {
1969 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
1970 } else {
1971 // Use in a phi is considered a use in the associated predecessor block
1972 use_c = use->in(0)->in(j);
1973 }
1974 set_ctrl(n_clone, use_c);
1975 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
1976 get_loop(use_c)->_body.push(n_clone);
1977 _igvn.register_new_node_with_optimizer(n_clone);
1978 #if !defined(PRODUCT)
1979 if (TracePartialPeeling) {
1980 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
1981 }
1982 #endif
1983 }
1984 return cloned;
1985 }
1986
1987
1988 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
1989 // clone "n" for special uses that are in the not_peeled region.
1990 // If these def-uses occur in separate blocks, the code generator
1991 // marks the method as not compilable. For example, if a "BoolNode"
1992 // is in a different basic block than the "IfNode" that uses it, then
1993 // the compilation is aborted in the code generator.
1994 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1995 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
1996 if (n->is_Phi() || n->is_Load()) {
1997 return;
1998 }
1999 assert(worklist.size() == 0, "should be empty");
2000 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2001 Node* use = n->fast_out(j);
2002 if ( not_peel.test(use->_idx) &&
2003 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2004 use->in(1) == n) {
2005 worklist.push(use);
2006 }
2007 }
2008 if (worklist.size() > 0) {
2009 // clone "n" and insert it between inputs of "n" and the use
2010 Node* n_clone = n->clone();
2011 loop->_body.push(n_clone);
2012 _igvn.register_new_node_with_optimizer(n_clone);
2013 set_ctrl(n_clone, get_ctrl(n));
2014 sink_list.push(n_clone);
2015 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2016 #if !defined(PRODUCT)
2017 if (TracePartialPeeling) {
2018 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2019 }
2020 #endif
2021 while( worklist.size() ) {
2022 Node *use = worklist.pop();
2023 _igvn.rehash_node_delayed(use);
2024 for (uint j = 1; j < use->req(); j++) {
2025 if (use->in(j) == n) {
2026 use->set_req(j, n_clone);
2027 }
2028 }
2029 }
2030 }
2031 }
2032
2033
2034 //------------------------------ insert_phi_for_loop -------------------------------------
2035 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2036 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2037 Node *phi = PhiNode::make(lp, back_edge_val);
2038 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2039 // Use existing phi if it already exists
2040 Node *hit = _igvn.hash_find_insert(phi);
2041 if( hit == NULL ) {
2042 _igvn.register_new_node_with_optimizer(phi);
2043 set_ctrl(phi, lp);
2044 } else {
2045 // Remove the new phi from the graph and use the hit
2046 _igvn.remove_dead_node(phi);
2047 phi = hit;
2048 }
2049 _igvn.replace_input_of(use, idx, phi);
2050 }
2051
2052 #ifdef ASSERT
2053 //------------------------------ is_valid_loop_partition -------------------------------------
2054 // Validate the loop partition sets: peel and not_peel
2055 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2056 VectorSet& not_peel ) {
2057 uint i;
2058 // Check that peel_list entries are in the peel set
2059 for (i = 0; i < peel_list.size(); i++) {
2060 if (!peel.test(peel_list.at(i)->_idx)) {
2061 return false;
2062 }
2063 }
2064 // Check at loop members are in one of peel set or not_peel set
2065 for (i = 0; i < loop->_body.size(); i++ ) {
2066 Node *def = loop->_body.at(i);
2067 uint di = def->_idx;
2068 // Check that peel set elements are in peel_list
2069 if (peel.test(di)) {
2070 if (not_peel.test(di)) {
2071 return false;
2072 }
2073 // Must be in peel_list also
2074 bool found = false;
2075 for (uint j = 0; j < peel_list.size(); j++) {
2076 if (peel_list.at(j)->_idx == di) {
2077 found = true;
2078 break;
2079 }
2080 }
2081 if (!found) {
2082 return false;
2083 }
2084 } else if (not_peel.test(di)) {
2085 if (peel.test(di)) {
2086 return false;
2087 }
2088 } else {
2089 return false;
2090 }
2091 }
2092 return true;
2093 }
2094
2095 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2096 // Ensure a use outside of loop is of the right form
2097 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2098 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2099 return (use->is_Phi() &&
2100 use_c->is_Region() && use_c->req() == 3 &&
2101 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2102 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2103 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2104 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2105 }
2106
2107 //------------------------------ is_valid_clone_loop_form -------------------------------------
2108 // Ensure that all uses outside of loop are of the right form
2109 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2110 uint orig_exit_idx, uint clone_exit_idx) {
2111 uint len = peel_list.size();
2112 for (uint i = 0; i < len; i++) {
2113 Node *def = peel_list.at(i);
2114
2115 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2116 Node *use = def->fast_out(j);
2117 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2118 if (!loop->is_member(get_loop(use_c))) {
2119 // use is not in the loop, check for correct structure
2120 if (use->in(0) == def) {
2121 // Okay
2122 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2123 return false;
2124 }
2125 }
2126 }
2127 }
2128 return true;
2129 }
2130 #endif
2131
2132 //------------------------------ partial_peel -------------------------------------
2133 // Partially peel (aka loop rotation) the top portion of a loop (called
2134 // the peel section below) by cloning it and placing one copy just before
2135 // the new loop head and the other copy at the bottom of the new loop.
2136 //
2137 // before after where it came from
2138 //
2139 // stmt1 stmt1
2140 // loop: stmt2 clone
2141 // stmt2 if condA goto exitA clone
2142 // if condA goto exitA new_loop: new
2143 // stmt3 stmt3 clone
2144 // if !condB goto loop if condB goto exitB clone
2145 // exitB: stmt2 orig
2146 // stmt4 if !condA goto new_loop orig
2147 // exitA: goto exitA
2148 // exitB:
2149 // stmt4
2150 // exitA:
2151 //
2152 // Step 1: find the cut point: an exit test on probable
2153 // induction variable.
2154 // Step 2: schedule (with cloning) operations in the peel
2155 // section that can be executed after the cut into
2156 // the section that is not peeled. This may need
2157 // to clone operations into exit blocks. For
2158 // instance, a reference to A[i] in the not-peel
2159 // section and a reference to B[i] in an exit block
2160 // may cause a left-shift of i by 2 to be placed
2161 // in the peel block. This step will clone the left
2162 // shift into the exit block and sink the left shift
2163 // from the peel to the not-peel section.
2164 // Step 3: clone the loop, retarget the control, and insert
2165 // phis for values that are live across the new loop
2166 // head. This is very dependent on the graph structure
2167 // from clone_loop. It creates region nodes for
2168 // exit control and associated phi nodes for values
2169 // flow out of the loop through that exit. The region
2170 // node is dominated by the clone's control projection.
2171 // So the clone's peel section is placed before the
2172 // new loop head, and the clone's not-peel section is
2173 // forms the top part of the new loop. The original
2174 // peel section forms the tail of the new loop.
2175 // Step 4: update the dominator tree and recompute the
2176 // dominator depth.
2177 //
2178 // orig
2179 //
2180 // stmt1
2181 // |
2182 // v
2183 // loop predicate
2184 // |
2185 // v
2186 // loop<----+
2187 // | |
2188 // stmt2 |
2189 // | |
2190 // v |
2191 // ifA |
2192 // / | |
2193 // v v |
2194 // false true ^ <-- last_peel
2195 // / | |
2196 // / ===|==cut |
2197 // / stmt3 | <-- first_not_peel
2198 // / | |
2199 // | v |
2200 // v ifB |
2201 // exitA: / \ |
2202 // / \ |
2203 // v v |
2204 // false true |
2205 // / \ |
2206 // / ----+
2207 // |
2208 // v
2209 // exitB:
2210 // stmt4
2211 //
2212 //
2213 // after clone loop
2214 //
2215 // stmt1
2216 // |
2217 // v
2218 // loop predicate
2219 // / \
2220 // clone / \ orig
2221 // / \
2222 // / \
2223 // v v
2224 // +---->loop loop<----+
2225 // | | | |
2226 // | stmt2 stmt2 |
2227 // | | | |
2228 // | v v |
2229 // | ifA ifA |
2230 // | | \ / | |
2231 // | v v v v |
2232 // ^ true false false true ^ <-- last_peel
2233 // | | ^ \ / | |
2234 // | cut==|== \ \ / ===|==cut |
2235 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2236 // | | dom | | | |
2237 // | v \ 1v v2 v |
2238 // | ifB regionA ifB |
2239 // | / \ | / \ |
2240 // | / \ v / \ |
2241 // | v v exitA: v v |
2242 // | true false false true |
2243 // | / ^ \ / \ |
2244 // +---- \ \ / ----+
2245 // dom \ /
2246 // \ 1v v2
2247 // regionB
2248 // |
2249 // v
2250 // exitB:
2251 // stmt4
2252 //
2253 //
2254 // after partial peel
2255 //
2256 // stmt1
2257 // |
2258 // v
2259 // loop predicate
2260 // /
2261 // clone / orig
2262 // / TOP
2263 // / \
2264 // v v
2265 // TOP->loop loop----+
2266 // | | |
2267 // stmt2 stmt2 |
2268 // | | |
2269 // v v |
2270 // ifA ifA |
2271 // | \ / | |
2272 // v v v v |
2273 // true false false true | <-- last_peel
2274 // | ^ \ / +------|---+
2275 // +->newloop \ \ / === ==cut | |
2276 // | stmt3 \ \ / TOP | |
2277 // | | dom | | stmt3 | | <-- first_not_peel
2278 // | v \ 1v v2 v | |
2279 // | ifB regionA ifB ^ v
2280 // | / \ | / \ | |
2281 // | / \ v / \ | |
2282 // | v v exitA: v v | |
2283 // | true false false true | |
2284 // | / ^ \ / \ | |
2285 // | | \ \ / v | |
2286 // | | dom \ / TOP | |
2287 // | | \ 1v v2 | |
2288 // ^ v regionB | |
2289 // | | | | |
2290 // | | v ^ v
2291 // | | exitB: | |
2292 // | | stmt4 | |
2293 // | +------------>-----------------+ |
2294 // | |
2295 // +-----------------<---------------------+
2296 //
2297 //
2298 // final graph
2299 //
2300 // stmt1
2301 // |
2302 // v
2303 // loop predicate
2304 // |
2305 // v
2306 // stmt2 clone
2307 // |
2308 // v
2309 // ........> ifA clone
2310 // : / |
2311 // dom / |
2312 // : v v
2313 // : false true
2314 // : | |
2315 // : | v
2316 // : | newloop<-----+
2317 // : | | |
2318 // : | stmt3 clone |
2319 // : | | |
2320 // : | v |
2321 // : | ifB |
2322 // : | / \ |
2323 // : | v v |
2324 // : | false true |
2325 // : | | | |
2326 // : | v stmt2 |
2327 // : | exitB: | |
2328 // : | stmt4 v |
2329 // : | ifA orig |
2330 // : | / \ |
2331 // : | / \ |
2332 // : | v v |
2333 // : | false true |
2334 // : | / \ |
2335 // : v v -----+
2336 // RegionA
2337 // |
2338 // v
2339 // exitA
2340 //
2341 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2342
2343 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2344 if (!loop->_head->is_Loop()) {
2345 return false; }
2346
2347 LoopNode *head = loop->_head->as_Loop();
2348
2349 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2350 return false;
2351 }
2352
2353 // Check for complex exit control
2354 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2355 Node *n = loop->_body.at(ii);
2356 int opc = n->Opcode();
2357 if (n->is_Call() ||
2358 opc == Op_Catch ||
2359 opc == Op_CatchProj ||
2360 opc == Op_Jump ||
2361 opc == Op_JumpProj) {
2362 #if !defined(PRODUCT)
2363 if (TracePartialPeeling) {
2364 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2365 }
2366 #endif
2367 return false;
2368 }
2369 }
2370
2371 int dd = dom_depth(head);
2372
2373 // Step 1: find cut point
2374
2375 // Walk up dominators to loop head looking for first loop exit
2376 // which is executed on every path thru loop.
2377 IfNode *peel_if = NULL;
2378 IfNode *peel_if_cmpu = NULL;
2379
2380 Node *iff = loop->tail();
2381 while( iff != head ) {
2382 if( iff->is_If() ) {
2383 Node *ctrl = get_ctrl(iff->in(1));
2384 if (ctrl->is_top()) return false; // Dead test on live IF.
2385 // If loop-varying exit-test, check for induction variable
2386 if( loop->is_member(get_loop(ctrl)) &&
2387 loop->is_loop_exit(iff) &&
2388 is_possible_iv_test(iff)) {
2389 Node* cmp = iff->in(1)->in(1);
2390 if (cmp->Opcode() == Op_CmpI) {
2391 peel_if = iff->as_If();
2392 } else {
2393 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2394 peel_if_cmpu = iff->as_If();
2395 }
2396 }
2397 }
2398 iff = idom(iff);
2399 }
2400 // Prefer signed compare over unsigned compare.
2401 IfNode* new_peel_if = NULL;
2402 if (peel_if == NULL) {
2403 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2404 return false; // No peel point found
2405 }
2406 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2407 if (new_peel_if == NULL) {
2408 return false; // No peel point found
2409 }
2410 peel_if = new_peel_if;
2411 }
2412 Node* last_peel = stay_in_loop(peel_if, loop);
2413 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2414 if (first_not_peeled == NULL || first_not_peeled == head) {
2415 return false;
2416 }
2417
2418 #if !defined(PRODUCT)
2419 if (TraceLoopOpts) {
2420 tty->print("PartialPeel ");
2421 loop->dump_head();
2422 }
2423
2424 if (TracePartialPeeling) {
2425 tty->print_cr("before partial peel one iteration");
2426 Node_List wl;
2427 Node* t = head->in(2);
2428 while (true) {
2429 wl.push(t);
2430 if (t == head) break;
2431 t = idom(t);
2432 }
2433 while (wl.size() > 0) {
2434 Node* tt = wl.pop();
2435 tt->dump();
2436 if (tt == last_peel) tty->print_cr("-- cut --");
2437 }
2438 }
2439 #endif
2440 ResourceArea *area = Thread::current()->resource_area();
2441 VectorSet peel(area);
2442 VectorSet not_peel(area);
2443 Node_List peel_list(area);
2444 Node_List worklist(area);
2445 Node_List sink_list(area);
2446
2447 // Set of cfg nodes to peel are those that are executable from
2448 // the head through last_peel.
2449 assert(worklist.size() == 0, "should be empty");
2450 worklist.push(head);
2451 peel.set(head->_idx);
2452 while (worklist.size() > 0) {
2453 Node *n = worklist.pop();
2454 if (n != last_peel) {
2455 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2456 Node* use = n->fast_out(j);
2457 if (use->is_CFG() &&
2458 loop->is_member(get_loop(use)) &&
2459 !peel.test_set(use->_idx)) {
2460 worklist.push(use);
2461 }
2462 }
2463 }
2464 }
2465
2466 // Set of non-cfg nodes to peel are those that are control
2467 // dependent on the cfg nodes.
2468 uint i;
2469 for(i = 0; i < loop->_body.size(); i++ ) {
2470 Node *n = loop->_body.at(i);
2471 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2472 if (peel.test(n_c->_idx)) {
2473 peel.set(n->_idx);
2474 } else {
2475 not_peel.set(n->_idx);
2476 }
2477 }
2478
2479 // Step 2: move operations from the peeled section down into the
2480 // not-peeled section
2481
2482 // Get a post order schedule of nodes in the peel region
2483 // Result in right-most operand.
2484 scheduled_nodelist(loop, peel, peel_list );
2485
2486 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2487
2488 // For future check for too many new phis
2489 uint old_phi_cnt = 0;
2490 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2491 Node* use = head->fast_out(j);
2492 if (use->is_Phi()) old_phi_cnt++;
2493 }
2494
2495 #if !defined(PRODUCT)
2496 if (TracePartialPeeling) {
2497 tty->print_cr("\npeeled list");
2498 }
2499 #endif
2500
2501 // Evacuate nodes in peel region into the not_peeled region if possible
2502 uint new_phi_cnt = 0;
2503 uint cloned_for_outside_use = 0;
2504 for (i = 0; i < peel_list.size();) {
2505 Node* n = peel_list.at(i);
2506 #if !defined(PRODUCT)
2507 if (TracePartialPeeling) n->dump();
2508 #endif
2509 bool incr = true;
2510 if ( !n->is_CFG() ) {
2511
2512 if ( has_use_in_set(n, not_peel) ) {
2513
2514 // If not used internal to the peeled region,
2515 // move "n" from peeled to not_peeled region.
2516
2517 if ( !has_use_internal_to_set(n, peel, loop) ) {
2518
2519 // if not pinned and not a load (which maybe anti-dependent on a store)
2520 // and not a CMove (Matcher expects only bool->cmove).
2521 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2522 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2523 sink_list.push(n);
2524 peel >>= n->_idx; // delete n from peel set.
2525 not_peel <<= n->_idx; // add n to not_peel set.
2526 peel_list.remove(i);
2527 incr = false;
2528 #if !defined(PRODUCT)
2529 if (TracePartialPeeling) {
2530 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2531 n->_idx, get_ctrl(n)->_idx);
2532 }
2533 #endif
2534 }
2535 } else {
2536 // Otherwise check for special def-use cases that span
2537 // the peel/not_peel boundary such as bool->if
2538 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2539 new_phi_cnt++;
2540 }
2541 }
2542 }
2543 if (incr) i++;
2544 }
2545
2546 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2547 #if !defined(PRODUCT)
2548 if (TracePartialPeeling) {
2549 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2550 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2551 }
2552 #endif
2553 if (new_peel_if != NULL) {
2554 remove_cmpi_loop_exit(new_peel_if, loop);
2555 }
2556 // Inhibit more partial peeling on this loop
2557 assert(!head->is_partial_peel_loop(), "not partial peeled");
2558 head->mark_partial_peel_failed();
2559 if (cloned_for_outside_use > 0) {
2560 // Terminate this round of loop opts because
2561 // the graph outside this loop was changed.
2562 C->set_major_progress();
2563 return true;
2564 }
2565 return false;
2566 }
2567
2568 // Step 3: clone loop, retarget control, and insert new phis
2569
2570 // Create new loop head for new phis and to hang
2571 // the nodes being moved (sinked) from the peel region.
2572 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2573 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2574 _igvn.register_new_node_with_optimizer(new_head);
2575 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2576 first_not_peeled->set_req(0, new_head);
2577 set_loop(new_head, loop);
2578 loop->_body.push(new_head);
2579 not_peel.set(new_head->_idx);
2580 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2581 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2582
2583 while (sink_list.size() > 0) {
2584 Node* n = sink_list.pop();
2585 set_ctrl(n, new_head);
2586 }
2587
2588 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2589
2590 clone_loop( loop, old_new, dd );
2591
2592 const uint clone_exit_idx = 1;
2593 const uint orig_exit_idx = 2;
2594 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2595
2596 Node* head_clone = old_new[head->_idx];
2597 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2598 Node* orig_tail_clone = head_clone->in(2);
2599
2600 // Add phi if "def" node is in peel set and "use" is not
2601
2602 for(i = 0; i < peel_list.size(); i++ ) {
2603 Node *def = peel_list.at(i);
2604 if (!def->is_CFG()) {
2605 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2606 Node *use = def->fast_out(j);
2607 if (has_node(use) && use->in(0) != C->top() &&
2608 (!peel.test(use->_idx) ||
2609 (use->is_Phi() && use->in(0) == head)) ) {
2610 worklist.push(use);
2611 }
2612 }
2613 while( worklist.size() ) {
2614 Node *use = worklist.pop();
2615 for (uint j = 1; j < use->req(); j++) {
2616 Node* n = use->in(j);
2617 if (n == def) {
2618
2619 // "def" is in peel set, "use" is not in peel set
2620 // or "use" is in the entry boundary (a phi) of the peel set
2621
2622 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2623
2624 if ( loop->is_member(get_loop( use_c )) ) {
2625 // use is in loop
2626 if (old_new[use->_idx] != NULL) { // null for dead code
2627 Node* use_clone = old_new[use->_idx];
2628 _igvn.replace_input_of(use, j, C->top());
2629 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2630 }
2631 } else {
2632 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2633 // use is not in the loop, check if the live range includes the cut
2634 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2635 if (not_peel.test(lp_if->_idx)) {
2636 assert(j == orig_exit_idx, "use from original loop");
2637 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2638 }
2639 }
2640 }
2641 }
2642 }
2643 }
2644 }
2645
2646 // Step 3b: retarget control
2647
2648 // Redirect control to the new loop head if a cloned node in
2649 // the not_peeled region has control that points into the peeled region.
2650 // This necessary because the cloned peeled region will be outside
2651 // the loop.
2652 // from to
2653 // cloned-peeled <---+
2654 // new_head_clone: | <--+
2655 // cloned-not_peeled in(0) in(0)
2656 // orig-peeled
2657
2658 for(i = 0; i < loop->_body.size(); i++ ) {
2659 Node *n = loop->_body.at(i);
2660 if (!n->is_CFG() && n->in(0) != NULL &&
2661 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2662 Node* n_clone = old_new[n->_idx];
2663 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2664 }
2665 }
2666
2667 // Backedge of the surviving new_head (the clone) is original last_peel
2668 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2669
2670 // Cut first node in original not_peel set
2671 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2672 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2673 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2674
2675 // Copy head_clone back-branch info to original head
2676 // and remove original head's loop entry and
2677 // clone head's back-branch
2678 _igvn.rehash_node_delayed(head); // Multiple edge updates
2679 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2680 head->set_req(LoopNode::LoopBackControl, C->top());
2681 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2682
2683 // Similarly modify the phis
2684 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2685 Node* use = head->fast_out(k);
2686 if (use->is_Phi() && use->outcnt() > 0) {
2687 Node* use_clone = old_new[use->_idx];
2688 _igvn.rehash_node_delayed(use); // Multiple edge updates
2689 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2690 use->set_req(LoopNode::LoopBackControl, C->top());
2691 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2692 }
2693 }
2694
2695 // Step 4: update dominator tree and dominator depth
2696
2697 set_idom(head, orig_tail_clone, dd);
2698 recompute_dom_depth();
2699
2700 // Inhibit more partial peeling on this loop
2701 new_head_clone->set_partial_peel_loop();
2702 C->set_major_progress();
2703 loop->record_for_igvn();
2704
2705 #if !defined(PRODUCT)
2706 if (TracePartialPeeling) {
2707 tty->print_cr("\nafter partial peel one iteration");
2708 Node_List wl(area);
2709 Node* t = last_peel;
2710 while (true) {
2711 wl.push(t);
2712 if (t == head_clone) break;
2713 t = idom(t);
2714 }
2715 while (wl.size() > 0) {
2716 Node* tt = wl.pop();
2717 if (tt == head) tty->print_cr("orig head");
2718 else if (tt == new_head_clone) tty->print_cr("new head");
2719 else if (tt == head_clone) tty->print_cr("clone head");
2720 tt->dump();
2721 }
2722 }
2723 #endif
2724 return true;
2725 }
2726
2727 //------------------------------reorg_offsets----------------------------------
2728 // Reorganize offset computations to lower register pressure. Mostly
2729 // prevent loop-fallout uses of the pre-incremented trip counter (which are
2730 // then alive with the post-incremented trip counter forcing an extra
2731 // register move)
2732 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
2733 // Perform it only for canonical counted loops.
2734 // Loop's shape could be messed up by iteration_split_impl.
2735 if (!loop->_head->is_CountedLoop())
2736 return;
2737 if (!loop->_head->as_Loop()->is_valid_counted_loop())
2738 return;
2739
2740 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2741 CountedLoopEndNode *cle = cl->loopexit();
2742 Node *exit = cle->proj_out(false);
2743 Node *phi = cl->phi();
2744
2745 // Check for the special case of folks using the pre-incremented
2746 // trip-counter on the fall-out path (forces the pre-incremented
2747 // and post-incremented trip counter to be live at the same time).
2748 // Fix this by adjusting to use the post-increment trip counter.
2749
2750 bool progress = true;
2751 while (progress) {
2752 progress = false;
2753 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
2754 Node* use = phi->fast_out(i); // User of trip-counter
2755 if (!has_ctrl(use)) continue;
2756 Node *u_ctrl = get_ctrl(use);
2757 if (use->is_Phi()) {
2758 u_ctrl = NULL;
2759 for (uint j = 1; j < use->req(); j++)
2760 if (use->in(j) == phi)
2761 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
2762 }
2763 IdealLoopTree *u_loop = get_loop(u_ctrl);
2764 // Look for loop-invariant use
2765 if (u_loop == loop) continue;
2766 if (loop->is_member(u_loop)) continue;
2767 // Check that use is live out the bottom. Assuming the trip-counter
2768 // update is right at the bottom, uses of of the loop middle are ok.
2769 if (dom_lca(exit, u_ctrl) != exit) continue;
2770 // Hit! Refactor use to use the post-incremented tripcounter.
2771 // Compute a post-increment tripcounter.
2772 Node *opaq = new Opaque2Node( C, cle->incr() );
2773 register_new_node( opaq, u_ctrl );
2774 Node *neg_stride = _igvn.intcon(-cle->stride_con());
2775 set_ctrl(neg_stride, C->root());
2776 Node *post = new AddINode( opaq, neg_stride);
2777 register_new_node( post, u_ctrl );
2778 _igvn.rehash_node_delayed(use);
2779 for (uint j = 1; j < use->req(); j++) {
2780 if (use->in(j) == phi)
2781 use->set_req(j, post);
2782 }
2783 // Since DU info changed, rerun loop
2784 progress = true;
2785 break;
2786 }
2787 }
2788
2789 }