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