Print this page
| Split |
Close |
| Expand all |
| Collapse all |
--- old/src/share/vm/opto/ifnode.cpp
+++ new/src/share/vm/opto/ifnode.cpp
1 1 /*
2 2 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation.
8 8 *
9 9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 12 * version 2 for more details (a copy is included in the LICENSE file that
13 13 * accompanied this code).
14 14 *
15 15 * You should have received a copy of the GNU General Public License version
16 16 * 2 along with this work; if not, write to the Free Software Foundation,
17 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 18 *
19 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 20 * or visit www.oracle.com if you need additional information or have any
21 21 * questions.
22 22 *
23 23 */
24 24
25 25 #include "precompiled.hpp"
26 26 #include "memory/allocation.inline.hpp"
27 27 #include "opto/addnode.hpp"
28 28 #include "opto/cfgnode.hpp"
29 29 #include "opto/connode.hpp"
30 30 #include "opto/loopnode.hpp"
31 31 #include "opto/phaseX.hpp"
32 32 #include "opto/runtime.hpp"
33 33 #include "opto/subnode.hpp"
34 34
35 35 // Portions of code courtesy of Clifford Click
36 36
37 37 // Optimization - Graph Style
38 38
39 39
40 40 extern int explicit_null_checks_elided;
41 41
42 42 //=============================================================================
43 43 //------------------------------Value------------------------------------------
44 44 // Return a tuple for whichever arm of the IF is reachable
45 45 const Type *IfNode::Value( PhaseTransform *phase ) const {
46 46 if( !in(0) ) return Type::TOP;
47 47 if( phase->type(in(0)) == Type::TOP )
48 48 return Type::TOP;
49 49 const Type *t = phase->type(in(1));
50 50 if( t == Type::TOP ) // data is undefined
51 51 return TypeTuple::IFNEITHER; // unreachable altogether
52 52 if( t == TypeInt::ZERO ) // zero, or false
53 53 return TypeTuple::IFFALSE; // only false branch is reachable
54 54 if( t == TypeInt::ONE ) // 1, or true
55 55 return TypeTuple::IFTRUE; // only true branch is reachable
56 56 assert( t == TypeInt::BOOL, "expected boolean type" );
57 57
58 58 return TypeTuple::IFBOTH; // No progress
59 59 }
60 60
61 61 const RegMask &IfNode::out_RegMask() const {
62 62 return RegMask::Empty;
63 63 }
64 64
65 65 //------------------------------split_if---------------------------------------
66 66 // Look for places where we merge constants, then test on the merged value.
67 67 // If the IF test will be constant folded on the path with the constant, we
68 68 // win by splitting the IF to before the merge point.
69 69 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
70 70 // I could be a lot more general here, but I'm trying to squeeze this
71 71 // in before the Christmas '98 break so I'm gonna be kinda restrictive
72 72 // on the patterns I accept. CNC
73 73
74 74 // Look for a compare of a constant and a merged value
75 75 Node *i1 = iff->in(1);
76 76 if( !i1->is_Bool() ) return NULL;
77 77 BoolNode *b = i1->as_Bool();
78 78 Node *cmp = b->in(1);
79 79 if( !cmp->is_Cmp() ) return NULL;
80 80 i1 = cmp->in(1);
81 81 if( i1 == NULL || !i1->is_Phi() ) return NULL;
82 82 PhiNode *phi = i1->as_Phi();
83 83 if( phi->is_copy() ) return NULL;
84 84 Node *con2 = cmp->in(2);
85 85 if( !con2->is_Con() ) return NULL;
86 86 // See that the merge point contains some constants
87 87 Node *con1=NULL;
88 88 uint i4;
89 89 for( i4 = 1; i4 < phi->req(); i4++ ) {
90 90 con1 = phi->in(i4);
91 91 if( !con1 ) return NULL; // Do not optimize partially collapsed merges
92 92 if( con1->is_Con() ) break; // Found a constant
93 93 // Also allow null-vs-not-null checks
94 94 const TypePtr *tp = igvn->type(con1)->isa_ptr();
95 95 if( tp && tp->_ptr == TypePtr::NotNull )
96 96 break;
97 97 }
98 98 if( i4 >= phi->req() ) return NULL; // Found no constants
99 99
100 100 igvn->C->set_has_split_ifs(true); // Has chance for split-if
101 101
102 102 // Make sure that the compare can be constant folded away
103 103 Node *cmp2 = cmp->clone();
104 104 cmp2->set_req(1,con1);
105 105 cmp2->set_req(2,con2);
106 106 const Type *t = cmp2->Value(igvn);
107 107 // This compare is dead, so whack it!
108 108 igvn->remove_dead_node(cmp2);
109 109 if( !t->singleton() ) return NULL;
110 110
111 111 // No intervening control, like a simple Call
112 112 Node *r = iff->in(0);
113 113 if( !r->is_Region() ) return NULL;
114 114 if( phi->region() != r ) return NULL;
115 115 // No other users of the cmp/bool
116 116 if (b->outcnt() != 1 || cmp->outcnt() != 1) {
117 117 //tty->print_cr("many users of cmp/bool");
118 118 return NULL;
119 119 }
120 120
121 121 // Make sure we can determine where all the uses of merged values go
122 122 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
123 123 Node* u = r->fast_out(j);
124 124 if( u == r ) continue;
125 125 if( u == iff ) continue;
126 126 if( u->outcnt() == 0 ) continue; // use is dead & ignorable
127 127 if( !u->is_Phi() ) {
128 128 /*
129 129 if( u->is_Start() ) {
130 130 tty->print_cr("Region has inlined start use");
131 131 } else {
132 132 tty->print_cr("Region has odd use");
133 133 u->dump(2);
134 134 }*/
135 135 return NULL;
136 136 }
137 137 if( u != phi ) {
138 138 // CNC - do not allow any other merged value
139 139 //tty->print_cr("Merging another value");
140 140 //u->dump(2);
141 141 return NULL;
142 142 }
143 143 // Make sure we can account for all Phi uses
144 144 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
145 145 Node* v = u->fast_out(k); // User of the phi
146 146 // CNC - Allow only really simple patterns.
147 147 // In particular I disallow AddP of the Phi, a fairly common pattern
148 148 if( v == cmp ) continue; // The compare is OK
149 149 if( (v->is_ConstraintCast()) &&
150 150 v->in(0)->in(0) == iff )
151 151 continue; // CastPP/II of the IfNode is OK
152 152 // Disabled following code because I cannot tell if exactly one
153 153 // path dominates without a real dominator check. CNC 9/9/1999
154 154 //uint vop = v->Opcode();
155 155 //if( vop == Op_Phi ) { // Phi from another merge point might be OK
156 156 // Node *r = v->in(0); // Get controlling point
157 157 // if( !r ) return NULL; // Degraded to a copy
158 158 // // Find exactly one path in (either True or False doms, but not IFF)
159 159 // int cnt = 0;
160 160 // for( uint i = 1; i < r->req(); i++ )
161 161 // if( r->in(i) && r->in(i)->in(0) == iff )
162 162 // cnt++;
163 163 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
164 164 //}
165 165 if( !v->is_Call() ) {
166 166 /*
167 167 if( v->Opcode() == Op_AddP ) {
168 168 tty->print_cr("Phi has AddP use");
169 169 } else if( v->Opcode() == Op_CastPP ) {
170 170 tty->print_cr("Phi has CastPP use");
171 171 } else if( v->Opcode() == Op_CastII ) {
172 172 tty->print_cr("Phi has CastII use");
173 173 } else {
174 174 tty->print_cr("Phi has use I cant be bothered with");
175 175 }
176 176 */
177 177 }
178 178 return NULL;
179 179
180 180 /* CNC - Cut out all the fancy acceptance tests
181 181 // Can we clone this use when doing the transformation?
182 182 // If all uses are from Phis at this merge or constants, then YES.
183 183 if( !v->in(0) && v != cmp ) {
184 184 tty->print_cr("Phi has free-floating use");
185 185 v->dump(2);
186 186 return NULL;
187 187 }
188 188 for( uint l = 1; l < v->req(); l++ ) {
189 189 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
190 190 !v->in(l)->is_Con() ) {
191 191 tty->print_cr("Phi has use");
192 192 v->dump(2);
193 193 return NULL;
194 194 } // End of if Phi-use input is neither Phi nor Constant
195 195 } // End of for all inputs to Phi-use
196 196 */
197 197 } // End of for all uses of Phi
198 198 } // End of for all uses of Region
199 199
200 200 // Only do this if the IF node is in a sane state
201 201 if (iff->outcnt() != 2)
202 202 return NULL;
203 203
204 204 // Got a hit! Do the Mondo Hack!
205 205 //
206 206 //ABC a1c def ghi B 1 e h A C a c d f g i
207 207 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
208 208 // cmp - 2 cmp - 2 cmp - 2
209 209 // bool bool_c bool_x
210 210 // if if_c if_x
211 211 // T F T F T F
212 212 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
213 213 //
214 214 // Split the paths coming into the merge point into 2 separate groups of
215 215 // merges. On the left will be all the paths feeding constants into the
216 216 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
217 217 // will fold up into a constant; this will let the Cmp fold up as well as
218 218 // all the control flow. Below the original IF we have 2 control
219 219 // dependent regions, 's' and 't'. Now we will merge the two paths
220 220 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite
221 221 // likely 2 or more) will promptly constant fold away.
222 222 PhaseGVN *phase = igvn;
223 223
224 224 // Make a region merging constants and a region merging the rest
225 225 uint req_c = 0;
226 226 Node* predicate_proj = NULL;
227 227 for (uint ii = 1; ii < r->req(); ii++) {
228 228 if (phi->in(ii) == con1) {
229 229 req_c++;
230 230 }
231 231 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
232 232 if (proj != NULL) {
233 233 assert(predicate_proj == NULL, "only one predicate entry expected");
234 234 predicate_proj = proj;
235 235 }
236 236 }
237 237 Node* predicate_c = NULL;
238 238 Node* predicate_x = NULL;
239 239 bool counted_loop = r->is_CountedLoop();
240 240
241 241 Node *region_c = new (igvn->C, req_c + 1) RegionNode(req_c + 1);
242 242 Node *phi_c = con1;
243 243 uint len = r->req();
244 244 Node *region_x = new (igvn->C, len - req_c) RegionNode(len - req_c);
245 245 Node *phi_x = PhiNode::make_blank(region_x, phi);
246 246 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
247 247 if (phi->in(i) == con1) {
248 248 region_c->init_req( i_c++, r ->in(i) );
249 249 if (r->in(i) == predicate_proj)
250 250 predicate_c = predicate_proj;
251 251 } else {
252 252 region_x->init_req( i_x, r ->in(i) );
253 253 phi_x ->init_req( i_x++, phi->in(i) );
254 254 if (r->in(i) == predicate_proj)
255 255 predicate_x = predicate_proj;
256 256 }
257 257 }
258 258
259 259 // Register the new RegionNodes but do not transform them. Cannot
260 260 // transform until the entire Region/Phi conglomerate has been hacked
261 261 // as a single huge transform.
262 262 igvn->register_new_node_with_optimizer( region_c );
263 263 igvn->register_new_node_with_optimizer( region_x );
264 264 // Prevent the untimely death of phi_x. Currently he has no uses. He is
265 265 // about to get one. If this only use goes away, then phi_x will look dead.
266 266 // However, he will be picking up some more uses down below.
267 267 Node *hook = new (igvn->C, 4) Node(4);
268 268 hook->init_req(0, phi_x);
269 269 hook->init_req(1, phi_c);
270 270 phi_x = phase->transform( phi_x );
271 271
272 272 // Make the compare
273 273 Node *cmp_c = phase->makecon(t);
274 274 Node *cmp_x = cmp->clone();
275 275 cmp_x->set_req(1,phi_x);
276 276 cmp_x->set_req(2,con2);
277 277 cmp_x = phase->transform(cmp_x);
278 278 // Make the bool
279 279 Node *b_c = phase->transform(new (igvn->C, 2) BoolNode(cmp_c,b->_test._test));
280 280 Node *b_x = phase->transform(new (igvn->C, 2) BoolNode(cmp_x,b->_test._test));
281 281 // Make the IfNode
282 282 IfNode *iff_c = new (igvn->C, 2) IfNode(region_c,b_c,iff->_prob,iff->_fcnt);
283 283 igvn->set_type_bottom(iff_c);
284 284 igvn->_worklist.push(iff_c);
285 285 hook->init_req(2, iff_c);
286 286
287 287 IfNode *iff_x = new (igvn->C, 2) IfNode(region_x,b_x,iff->_prob, iff->_fcnt);
288 288 igvn->set_type_bottom(iff_x);
289 289 igvn->_worklist.push(iff_x);
290 290 hook->init_req(3, iff_x);
291 291
292 292 // Make the true/false arms
293 293 Node *iff_c_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_c));
294 294 Node *iff_c_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_c));
295 295 if (predicate_c != NULL) {
296 296 assert(predicate_x == NULL, "only one predicate entry expected");
297 297 // Clone loop predicates to each path
298 298 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
299 299 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
300 300 }
301 301 Node *iff_x_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_x));
302 302 Node *iff_x_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_x));
303 303 if (predicate_x != NULL) {
304 304 assert(predicate_c == NULL, "only one predicate entry expected");
305 305 // Clone loop predicates to each path
306 306 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
307 307 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
308 308 }
309 309
310 310 // Merge the TRUE paths
311 311 Node *region_s = new (igvn->C, 3) RegionNode(3);
312 312 igvn->_worklist.push(region_s);
313 313 region_s->init_req(1, iff_c_t);
314 314 region_s->init_req(2, iff_x_t);
315 315 igvn->register_new_node_with_optimizer( region_s );
316 316
317 317 // Merge the FALSE paths
318 318 Node *region_f = new (igvn->C, 3) RegionNode(3);
319 319 igvn->_worklist.push(region_f);
320 320 region_f->init_req(1, iff_c_f);
321 321 region_f->init_req(2, iff_x_f);
322 322 igvn->register_new_node_with_optimizer( region_f );
323 323
324 324 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
325 325 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead
326 326 cmp->set_req(2,NULL);
327 327 // Check for all uses of the Phi and give them a new home.
328 328 // The 'cmp' got cloned, but CastPP/IIs need to be moved.
329 329 Node *phi_s = NULL; // do not construct unless needed
330 330 Node *phi_f = NULL; // do not construct unless needed
331 331 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
332 332 Node* v = phi->last_out(i2);// User of the phi
333 333 igvn->hash_delete(v); // Have to fixup other Phi users
334 334 igvn->_worklist.push(v);
335 335 uint vop = v->Opcode();
336 336 Node *proj = NULL;
337 337 if( vop == Op_Phi ) { // Remote merge point
338 338 Node *r = v->in(0);
339 339 for (uint i3 = 1; i3 < r->req(); i3++)
340 340 if (r->in(i3) && r->in(i3)->in(0) == iff) {
341 341 proj = r->in(i3);
342 342 break;
343 343 }
344 344 } else if( v->is_ConstraintCast() ) {
345 345 proj = v->in(0); // Controlling projection
346 346 } else {
347 347 assert( 0, "do not know how to handle this guy" );
348 348 }
349 349
350 350 Node *proj_path_data, *proj_path_ctrl;
351 351 if( proj->Opcode() == Op_IfTrue ) {
352 352 if( phi_s == NULL ) {
353 353 // Only construct phi_s if needed, otherwise provides
354 354 // interfering use.
355 355 phi_s = PhiNode::make_blank(region_s,phi);
356 356 phi_s->init_req( 1, phi_c );
357 357 phi_s->init_req( 2, phi_x );
358 358 hook->add_req(phi_s);
359 359 phi_s = phase->transform(phi_s);
360 360 }
361 361 proj_path_data = phi_s;
362 362 proj_path_ctrl = region_s;
363 363 } else {
364 364 if( phi_f == NULL ) {
365 365 // Only construct phi_f if needed, otherwise provides
366 366 // interfering use.
367 367 phi_f = PhiNode::make_blank(region_f,phi);
368 368 phi_f->init_req( 1, phi_c );
369 369 phi_f->init_req( 2, phi_x );
370 370 hook->add_req(phi_f);
371 371 phi_f = phase->transform(phi_f);
372 372 }
373 373 proj_path_data = phi_f;
374 374 proj_path_ctrl = region_f;
375 375 }
376 376
377 377 // Fixup 'v' for for the split
378 378 if( vop == Op_Phi ) { // Remote merge point
379 379 uint i;
380 380 for( i = 1; i < v->req(); i++ )
381 381 if( v->in(i) == phi )
382 382 break;
383 383 v->set_req(i, proj_path_data );
384 384 } else if( v->is_ConstraintCast() ) {
385 385 v->set_req(0, proj_path_ctrl );
386 386 v->set_req(1, proj_path_data );
387 387 } else
388 388 ShouldNotReachHere();
389 389 }
390 390
391 391 // Now replace the original iff's True/False with region_s/region_t.
392 392 // This makes the original iff go dead.
393 393 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
394 394 Node* p = iff->last_out(i3);
395 395 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
396 396 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
397 397 // Replace p with u
398 398 igvn->add_users_to_worklist(p);
399 399 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
400 400 Node* x = p->last_out(l);
401 401 igvn->hash_delete(x);
402 402 uint uses_found = 0;
403 403 for( uint j = 0; j < x->req(); j++ ) {
404 404 if( x->in(j) == p ) {
405 405 x->set_req(j, u);
406 406 uses_found++;
407 407 }
408 408 }
409 409 l -= uses_found; // we deleted 1 or more copies of this edge
410 410 }
411 411 igvn->remove_dead_node(p);
412 412 }
413 413
414 414 // Force the original merge dead
415 415 igvn->hash_delete(r);
416 416 // First, remove region's dead users.
417 417 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
418 418 Node* u = r->last_out(l);
419 419 if( u == r ) {
420 420 r->set_req(0, NULL);
421 421 } else {
422 422 assert(u->outcnt() == 0, "only dead users");
423 423 igvn->remove_dead_node(u);
424 424 }
425 425 l -= 1;
426 426 }
427 427 igvn->remove_dead_node(r);
428 428
429 429 // Now remove the bogus extra edges used to keep things alive
430 430 igvn->remove_dead_node( hook );
431 431
432 432 // Must return either the original node (now dead) or a new node
433 433 // (Do not return a top here, since that would break the uniqueness of top.)
434 434 return new (igvn->C, 1) ConINode(TypeInt::ZERO);
435 435 }
436 436
437 437 //------------------------------is_range_check---------------------------------
438 438 // Return 0 if not a range check. Return 1 if a range check and set index and
439 439 // offset. Return 2 if we had to negate the test. Index is NULL if the check
440 440 // is versus a constant.
441 441 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) {
442 442 Node* b = in(1);
443 443 if (b == NULL || !b->is_Bool()) return 0;
444 444 BoolNode* bn = b->as_Bool();
445 445 Node* cmp = bn->in(1);
446 446 if (cmp == NULL) return 0;
447 447 if (cmp->Opcode() != Op_CmpU) return 0;
448 448
449 449 Node* l = cmp->in(1);
450 450 Node* r = cmp->in(2);
451 451 int flip_test = 1;
452 452 if (bn->_test._test == BoolTest::le) {
453 453 l = cmp->in(2);
454 454 r = cmp->in(1);
455 455 flip_test = 2;
456 456 } else if (bn->_test._test != BoolTest::lt) {
457 457 return 0;
458 458 }
459 459 if (l->is_top()) return 0; // Top input means dead test
460 460 if (r->Opcode() != Op_LoadRange) return 0;
461 461
462 462 // We have recognized one of these forms:
463 463 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
464 464 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
465 465
466 466 // Make sure it's a real range check by requiring an uncommon trap
467 467 // along the OOB path. Otherwise, it's possible that the user wrote
468 468 // something which optimized to look like a range check but behaves
469 469 // in some other way.
470 470 Node* iftrap = proj_out(flip_test == 2 ? true : false);
471 471 bool found_trap = false;
472 472 if (iftrap != NULL) {
473 473 Node* u = iftrap->unique_ctrl_out();
474 474 if (u != NULL) {
475 475 // It could be a merge point (Region) for uncommon trap.
476 476 if (u->is_Region()) {
477 477 Node* c = u->unique_ctrl_out();
478 478 if (c != NULL) {
479 479 iftrap = u;
480 480 u = c;
481 481 }
482 482 }
483 483 if (u->in(0) == iftrap && u->is_CallStaticJava()) {
484 484 int req = u->as_CallStaticJava()->uncommon_trap_request();
485 485 if (Deoptimization::trap_request_reason(req) ==
486 486 Deoptimization::Reason_range_check) {
487 487 found_trap = true;
488 488 }
489 489 }
490 490 }
491 491 }
492 492 if (!found_trap) return 0; // sorry, no cigar
493 493
494 494 // Look for index+offset form
495 495 Node* ind = l;
496 496 jint off = 0;
497 497 if (l->is_top()) {
498 498 return 0;
499 499 } else if (l->is_Add()) {
500 500 if ((off = l->in(1)->find_int_con(0)) != 0) {
501 501 ind = l->in(2);
502 502 } else if ((off = l->in(2)->find_int_con(0)) != 0) {
503 503 ind = l->in(1);
504 504 }
505 505 } else if ((off = l->find_int_con(-1)) >= 0) {
506 506 // constant offset with no variable index
507 507 ind = NULL;
508 508 } else {
509 509 // variable index with no constant offset (or dead negative index)
510 510 off = 0;
511 511 }
512 512
513 513 // Return all the values:
514 514 index = ind;
515 515 offset = off;
516 516 range = r;
517 517 return flip_test;
518 518 }
519 519
520 520 //------------------------------adjust_check-----------------------------------
521 521 // Adjust (widen) a prior range check
522 522 static void adjust_check(Node* proj, Node* range, Node* index,
523 523 int flip, jint off_lo, PhaseIterGVN* igvn) {
524 524 PhaseGVN *gvn = igvn;
525 525 // Break apart the old check
526 526 Node *iff = proj->in(0);
527 527 Node *bol = iff->in(1);
528 528 if( bol->is_top() ) return; // In case a partially dead range check appears
529 529 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
530 530 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
531 531 if( !bol->is_Bool() ) return;
532 532
533 533 Node *cmp = bol->in(1);
534 534 // Compute a new check
535 535 Node *new_add = gvn->intcon(off_lo);
536 536 if( index ) {
537 537 new_add = off_lo ? gvn->transform(new (gvn->C, 3) AddINode( index, new_add )) : index;
538 538 }
|
↓ open down ↓ |
538 lines elided |
↑ open up ↑ |
539 539 Node *new_cmp = (flip == 1)
540 540 ? new (gvn->C, 3) CmpUNode( new_add, range )
541 541 : new (gvn->C, 3) CmpUNode( range, new_add );
542 542 new_cmp = gvn->transform(new_cmp);
543 543 // See if no need to adjust the existing check
544 544 if( new_cmp == cmp ) return;
545 545 // Else, adjust existing check
546 546 Node *new_bol = gvn->transform( new (gvn->C, 2) BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
547 547 igvn->hash_delete( iff );
548 548 iff->set_req_X( 1, new_bol, igvn );
549 + igvn->_worklist.push( iff );
549 550 }
550 551
551 552 //------------------------------up_one_dom-------------------------------------
552 553 // Walk up the dominator tree one step. Return NULL at root or true
553 554 // complex merges. Skips through small diamonds.
554 555 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
555 556 Node *dom = curr->in(0);
556 557 if( !dom ) // Found a Region degraded to a copy?
557 558 return curr->nonnull_req(); // Skip thru it
558 559
559 560 if( curr != dom ) // Normal walk up one step?
560 561 return dom;
561 562
562 563 // Use linear_only if we are still parsing, since we cannot
563 564 // trust the regions to be fully filled in.
564 565 if (linear_only)
565 566 return NULL;
566 567
567 568 if( dom->is_Root() )
568 569 return NULL;
569 570
570 571 // Else hit a Region. Check for a loop header
571 572 if( dom->is_Loop() )
572 573 return dom->in(1); // Skip up thru loops
573 574
574 575 // Check for small diamonds
575 576 Node *din1, *din2, *din3, *din4;
576 577 if( dom->req() == 3 && // 2-path merge point
577 578 (din1 = dom ->in(1)) && // Left path exists
578 579 (din2 = dom ->in(2)) && // Right path exists
579 580 (din3 = din1->in(0)) && // Left path up one
580 581 (din4 = din2->in(0)) ) { // Right path up one
581 582 if( din3->is_Call() && // Handle a slow-path call on either arm
582 583 (din3 = din3->in(0)) )
583 584 din3 = din3->in(0);
584 585 if( din4->is_Call() && // Handle a slow-path call on either arm
585 586 (din4 = din4->in(0)) )
586 587 din4 = din4->in(0);
587 588 if( din3 == din4 && din3->is_If() )
588 589 return din3; // Skip around diamonds
589 590 }
590 591
591 592 // Give up the search at true merges
592 593 return NULL; // Dead loop? Or hit root?
593 594 }
594 595
595 596
596 597 //------------------------------filtered_int_type--------------------------------
597 598 // Return a possibly more restrictive type for val based on condition control flow for an if
598 599 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) {
599 600 assert(if_proj &&
600 601 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
601 602 if (if_proj->in(0) && if_proj->in(0)->is_If()) {
602 603 IfNode* iff = if_proj->in(0)->as_If();
603 604 if (iff->in(1) && iff->in(1)->is_Bool()) {
604 605 BoolNode* bol = iff->in(1)->as_Bool();
605 606 if (bol->in(1) && bol->in(1)->is_Cmp()) {
606 607 const CmpNode* cmp = bol->in(1)->as_Cmp();
607 608 if (cmp->in(1) == val) {
608 609 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
609 610 if (cmp2_t != NULL) {
610 611 jint lo = cmp2_t->_lo;
611 612 jint hi = cmp2_t->_hi;
612 613 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
613 614 switch (msk) {
614 615 case BoolTest::ne:
615 616 // Can't refine type
616 617 return NULL;
617 618 case BoolTest::eq:
618 619 return cmp2_t;
619 620 case BoolTest::lt:
620 621 lo = TypeInt::INT->_lo;
621 622 if (hi - 1 < hi) {
622 623 hi = hi - 1;
623 624 }
624 625 break;
625 626 case BoolTest::le:
626 627 lo = TypeInt::INT->_lo;
627 628 break;
628 629 case BoolTest::gt:
629 630 if (lo + 1 > lo) {
630 631 lo = lo + 1;
631 632 }
632 633 hi = TypeInt::INT->_hi;
633 634 break;
634 635 case BoolTest::ge:
635 636 // lo unchanged
636 637 hi = TypeInt::INT->_hi;
637 638 break;
638 639 }
639 640 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
640 641 return rtn_t;
641 642 }
642 643 }
643 644 }
644 645 }
645 646 }
646 647 return NULL;
647 648 }
648 649
649 650 //------------------------------fold_compares----------------------------
650 651 // See if a pair of CmpIs can be converted into a CmpU. In some cases
651 652 // the direction of this if is determined by the preceding if so it
652 653 // can be eliminate entirely. Given an if testing (CmpI n c) check
653 654 // for an immediately control dependent if that is testing (CmpI n c2)
654 655 // and has one projection leading to this if and the other projection
655 656 // leading to a region that merges one of this ifs control
656 657 // projections.
657 658 //
658 659 // If
659 660 // / |
660 661 // / |
661 662 // / |
662 663 // If |
663 664 // /\ |
664 665 // / \ |
665 666 // / \ |
666 667 // / Region
667 668 //
668 669 Node* IfNode::fold_compares(PhaseGVN* phase) {
669 670 if (!EliminateAutoBox || Opcode() != Op_If) return NULL;
670 671
671 672 Node* this_cmp = in(1)->in(1);
672 673 if (this_cmp != NULL && this_cmp->Opcode() == Op_CmpI &&
673 674 this_cmp->in(2)->is_Con() && this_cmp->in(2) != phase->C->top()) {
674 675 Node* ctrl = in(0);
675 676 BoolNode* this_bool = in(1)->as_Bool();
676 677 Node* n = this_cmp->in(1);
677 678 int hi = this_cmp->in(2)->get_int();
678 679 if (ctrl != NULL && ctrl->is_Proj() && ctrl->outcnt() == 1 &&
679 680 ctrl->in(0)->is_If() &&
680 681 ctrl->in(0)->outcnt() == 2 &&
681 682 ctrl->in(0)->in(1)->is_Bool() &&
682 683 ctrl->in(0)->in(1)->in(1)->Opcode() == Op_CmpI &&
683 684 ctrl->in(0)->in(1)->in(1)->in(2)->is_Con() &&
684 685 ctrl->in(0)->in(1)->in(1)->in(1) == n) {
685 686 IfNode* dom_iff = ctrl->in(0)->as_If();
686 687 Node* otherproj = dom_iff->proj_out(!ctrl->as_Proj()->_con);
687 688 if (otherproj->outcnt() == 1 && otherproj->unique_out()->is_Region() &&
688 689 this_bool->_test._test != BoolTest::ne && this_bool->_test._test != BoolTest::eq) {
689 690 // Identify which proj goes to the region and which continues on
690 691 RegionNode* region = otherproj->unique_out()->as_Region();
691 692 Node* success = NULL;
692 693 Node* fail = NULL;
693 694 for (int i = 0; i < 2; i++) {
694 695 Node* proj = proj_out(i);
695 696 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
696 697 success = proj;
697 698 } else if (fail == NULL) {
698 699 fail = proj;
699 700 } else {
700 701 success = fail = NULL;
701 702 }
702 703 }
703 704 if (success != NULL && fail != NULL && !region->has_phi()) {
704 705 int lo = dom_iff->in(1)->in(1)->in(2)->get_int();
705 706 BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
706 707 Node* dom_cmp = dom_bool->in(1);
707 708 const TypeInt* failtype = filtered_int_type(phase, n, ctrl);
708 709 if (failtype != NULL) {
709 710 const TypeInt* type2 = filtered_int_type(phase, n, fail);
710 711 if (type2 != NULL) {
711 712 failtype = failtype->join(type2)->is_int();
712 713 } else {
713 714 failtype = NULL;
714 715 }
715 716 }
716 717
717 718 if (failtype != NULL &&
718 719 dom_bool->_test._test != BoolTest::ne && dom_bool->_test._test != BoolTest::eq) {
719 720 int bound = failtype->_hi - failtype->_lo + 1;
720 721 if (failtype->_hi != max_jint && failtype->_lo != min_jint && bound > 1) {
721 722 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) hi)
722 723 BoolTest::mask cond = fail->as_Proj()->_con ? BoolTest::lt : BoolTest::ge;
723 724 Node* adjusted = phase->transform(new (phase->C, 3) SubINode(n, phase->intcon(failtype->_lo)));
724 725 Node* newcmp = phase->transform(new (phase->C, 3) CmpUNode(adjusted, phase->intcon(bound)));
725 726 Node* newbool = phase->transform(new (phase->C, 2) BoolNode(newcmp, cond));
726 727 phase->hash_delete(dom_iff);
727 728 dom_iff->set_req(1, phase->intcon(ctrl->as_Proj()->_con));
728 729 phase->is_IterGVN()->_worklist.push(dom_iff);
729 730 phase->hash_delete(this);
730 731 set_req(1, newbool);
731 732 return this;
732 733 }
733 734 if (failtype->_lo > failtype->_hi) {
734 735 // previous if determines the result of this if so
735 736 // replace Bool with constant
736 737 phase->hash_delete(this);
737 738 set_req(1, phase->intcon(success->as_Proj()->_con));
738 739 return this;
739 740 }
740 741 }
741 742 }
742 743 }
743 744 }
744 745 }
745 746 return NULL;
746 747 }
747 748
748 749 //------------------------------remove_useless_bool----------------------------
749 750 // Check for people making a useless boolean: things like
750 751 // if( (x < y ? true : false) ) { ... }
751 752 // Replace with if( x < y ) { ... }
752 753 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
753 754 Node *i1 = iff->in(1);
754 755 if( !i1->is_Bool() ) return NULL;
755 756 BoolNode *bol = i1->as_Bool();
756 757
757 758 Node *cmp = bol->in(1);
758 759 if( cmp->Opcode() != Op_CmpI ) return NULL;
759 760
760 761 // Must be comparing against a bool
761 762 const Type *cmp2_t = phase->type( cmp->in(2) );
762 763 if( cmp2_t != TypeInt::ZERO &&
763 764 cmp2_t != TypeInt::ONE )
764 765 return NULL;
765 766
766 767 // Find a prior merge point merging the boolean
767 768 i1 = cmp->in(1);
768 769 if( !i1->is_Phi() ) return NULL;
769 770 PhiNode *phi = i1->as_Phi();
770 771 if( phase->type( phi ) != TypeInt::BOOL )
771 772 return NULL;
772 773
773 774 // Check for diamond pattern
774 775 int true_path = phi->is_diamond_phi();
775 776 if( true_path == 0 ) return NULL;
776 777
777 778 // Make sure that iff and the control of the phi are different. This
778 779 // should really only happen for dead control flow since it requires
779 780 // an illegal cycle.
780 781 if (phi->in(0)->in(1)->in(0) == iff) return NULL;
781 782
782 783 // phi->region->if_proj->ifnode->bool->cmp
783 784 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
784 785
785 786 // Now get the 'sense' of the test correct so we can plug in
786 787 // either iff2->in(1) or its complement.
787 788 int flip = 0;
788 789 if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
789 790 else if( bol->_test._test != BoolTest::eq ) return NULL;
790 791 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
791 792
792 793 const Type *phi1_t = phase->type( phi->in(1) );
793 794 const Type *phi2_t = phase->type( phi->in(2) );
794 795 // Check for Phi(0,1) and flip
795 796 if( phi1_t == TypeInt::ZERO ) {
796 797 if( phi2_t != TypeInt::ONE ) return NULL;
797 798 flip = 1-flip;
798 799 } else {
799 800 // Check for Phi(1,0)
800 801 if( phi1_t != TypeInt::ONE ) return NULL;
801 802 if( phi2_t != TypeInt::ZERO ) return NULL;
802 803 }
803 804 if( true_path == 2 ) {
804 805 flip = 1-flip;
805 806 }
806 807
807 808 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
808 809 assert(new_bol != iff->in(1), "must make progress");
809 810 iff->set_req(1, new_bol);
810 811 // Intervening diamond probably goes dead
811 812 phase->C->set_major_progress();
812 813 return iff;
813 814 }
814 815
815 816 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
816 817
817 818 //------------------------------Ideal------------------------------------------
818 819 // Return a node which is more "ideal" than the current node. Strip out
819 820 // control copies
820 821 Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
821 822 if (remove_dead_region(phase, can_reshape)) return this;
822 823 // No Def-Use info?
823 824 if (!can_reshape) return NULL;
824 825 PhaseIterGVN *igvn = phase->is_IterGVN();
825 826
826 827 // Don't bother trying to transform a dead if
827 828 if (in(0)->is_top()) return NULL;
828 829 // Don't bother trying to transform an if with a dead test
829 830 if (in(1)->is_top()) return NULL;
830 831 // Another variation of a dead test
831 832 if (in(1)->is_Con()) return NULL;
832 833 // Another variation of a dead if
833 834 if (outcnt() < 2) return NULL;
834 835
835 836 // Canonicalize the test.
836 837 Node* idt_if = idealize_test(phase, this);
837 838 if (idt_if != NULL) return idt_if;
838 839
839 840 // Try to split the IF
840 841 Node *s = split_if(this, igvn);
841 842 if (s != NULL) return s;
842 843
843 844 // Check for people making a useless boolean: things like
844 845 // if( (x < y ? true : false) ) { ... }
845 846 // Replace with if( x < y ) { ... }
846 847 Node *bol2 = remove_useless_bool(this, phase);
847 848 if( bol2 ) return bol2;
848 849
849 850 // Setup to scan up the CFG looking for a dominating test
850 851 Node *dom = in(0);
851 852 Node *prev_dom = this;
852 853
853 854 // Check for range-check vs other kinds of tests
854 855 Node *index1, *range1;
855 856 jint offset1;
856 857 int flip1 = is_range_check(range1, index1, offset1);
857 858 if( flip1 ) {
858 859 Node *first_prev_dom = NULL;
859 860
860 861 // Try to remove extra range checks. All 'up_one_dom' gives up at merges
861 862 // so all checks we inspect post-dominate the top-most check we find.
862 863 // If we are going to fail the current check and we reach the top check
863 864 // then we are guaranteed to fail, so just start interpreting there.
864 865 // We 'expand' the top 2 range checks to include all post-dominating
865 866 // checks.
866 867
867 868 // The top 2 range checks seen
868 869 Node *prev_chk1 = NULL;
869 870 Node *prev_chk2 = NULL;
870 871 // Low and high offsets seen so far
871 872 jint off_lo = offset1;
872 873 jint off_hi = offset1;
873 874
874 875 // Scan for the top 2 checks and collect range of offsets
875 876 for( int dist = 0; dist < 999; dist++ ) { // Range-Check scan limit
876 877 if( dom->Opcode() == Op_If && // Not same opcode?
877 878 prev_dom->in(0) == dom ) { // One path of test does dominate?
878 879 if( dom == this ) return NULL; // dead loop
879 880 // See if this is a range check
880 881 Node *index2, *range2;
881 882 jint offset2;
882 883 int flip2 = dom->as_If()->is_range_check(range2, index2, offset2);
883 884 // See if this is a _matching_ range check, checking against
884 885 // the same array bounds.
885 886 if( flip2 == flip1 && range2 == range1 && index2 == index1 &&
886 887 dom->outcnt() == 2 ) {
887 888 // Gather expanded bounds
888 889 off_lo = MIN2(off_lo,offset2);
889 890 off_hi = MAX2(off_hi,offset2);
890 891 // Record top 2 range checks
891 892 prev_chk2 = prev_chk1;
892 893 prev_chk1 = prev_dom;
893 894 // If we match the test exactly, then the top test covers
894 895 // both our lower and upper bounds.
895 896 if( dom->in(1) == in(1) )
896 897 prev_chk2 = prev_chk1;
897 898 }
898 899 }
899 900 prev_dom = dom;
900 901 dom = up_one_dom( dom );
901 902 if( !dom ) break;
902 903 }
903 904
904 905
905 906 // Attempt to widen the dominating range check to cover some later
906 907 // ones. Since range checks "fail" by uncommon-trapping to the
907 908 // interpreter, widening a check can make us speculative enter the
908 909 // interpreter. If we see range-check deopt's, do not widen!
909 910 if (!phase->C->allow_range_check_smearing()) return NULL;
910 911
911 912 // Constant indices only need to check the upper bound.
912 913 // Non-constance indices must check both low and high.
913 914 if( index1 ) {
914 915 // Didn't find 2 prior covering checks, so cannot remove anything.
915 916 if( !prev_chk2 ) return NULL;
916 917 // 'Widen' the offsets of the 1st and 2nd covering check
917 918 adjust_check( prev_chk1, range1, index1, flip1, off_lo, igvn );
918 919 // Do not call adjust_check twice on the same projection
919 920 // as the first call may have transformed the BoolNode to a ConI
920 921 if( prev_chk1 != prev_chk2 ) {
921 922 adjust_check( prev_chk2, range1, index1, flip1, off_hi, igvn );
922 923 }
923 924 // Test is now covered by prior checks, dominate it out
924 925 prev_dom = prev_chk2;
925 926 } else {
926 927 // Didn't find prior covering check, so cannot remove anything.
927 928 if( !prev_chk1 ) return NULL;
928 929 // 'Widen' the offset of the 1st and only covering check
929 930 adjust_check( prev_chk1, range1, index1, flip1, off_hi, igvn );
930 931 // Test is now covered by prior checks, dominate it out
931 932 prev_dom = prev_chk1;
932 933 }
933 934
934 935
935 936 } else { // Scan for an equivalent test
936 937
937 938 Node *cmp;
938 939 int dist = 0; // Cutoff limit for search
939 940 int op = Opcode();
940 941 if( op == Op_If &&
941 942 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) {
942 943 if( cmp->in(2) != NULL && // make sure cmp is not already dead
943 944 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) {
944 945 dist = 64; // Limit for null-pointer scans
945 946 } else {
946 947 dist = 4; // Do not bother for random pointer tests
947 948 }
948 949 } else {
949 950 dist = 4; // Limit for random junky scans
950 951 }
951 952
952 953 // Normal equivalent-test check.
953 954 if( !dom ) return NULL; // Dead loop?
954 955
955 956 Node* result = fold_compares(phase);
956 957 if (result != NULL) {
957 958 return result;
958 959 }
959 960
960 961 // Search up the dominator tree for an If with an identical test
961 962 while( dom->Opcode() != op || // Not same opcode?
962 963 dom->in(1) != in(1) || // Not same input 1?
963 964 (req() == 3 && dom->in(2) != in(2)) || // Not same input 2?
964 965 prev_dom->in(0) != dom ) { // One path of test does not dominate?
965 966 if( dist < 0 ) return NULL;
966 967
967 968 dist--;
968 969 prev_dom = dom;
969 970 dom = up_one_dom( dom );
970 971 if( !dom ) return NULL;
971 972 }
972 973
973 974 // Check that we did not follow a loop back to ourselves
974 975 if( this == dom )
975 976 return NULL;
976 977
977 978 if( dist > 2 ) // Add to count of NULL checks elided
978 979 explicit_null_checks_elided++;
979 980
980 981 } // End of Else scan for an equivalent test
981 982
982 983 // Hit! Remove this IF
983 984 #ifndef PRODUCT
984 985 if( TraceIterativeGVN ) {
985 986 tty->print(" Removing IfNode: "); this->dump();
986 987 }
987 988 if( VerifyOpto && !phase->allow_progress() ) {
988 989 // Found an equivalent dominating test,
989 990 // we can not guarantee reaching a fix-point for these during iterativeGVN
990 991 // since intervening nodes may not change.
991 992 return NULL;
992 993 }
993 994 #endif
994 995
995 996 // Replace dominated IfNode
996 997 dominated_by( prev_dom, igvn );
997 998
998 999 // Must return either the original node (now dead) or a new node
999 1000 // (Do not return a top here, since that would break the uniqueness of top.)
1000 1001 return new (phase->C, 1) ConINode(TypeInt::ZERO);
1001 1002 }
1002 1003
1003 1004 //------------------------------dominated_by-----------------------------------
1004 1005 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) {
1005 1006 igvn->hash_delete(this); // Remove self to prevent spurious V-N
1006 1007 Node *idom = in(0);
1007 1008 // Need opcode to decide which way 'this' test goes
1008 1009 int prev_op = prev_dom->Opcode();
1009 1010 Node *top = igvn->C->top(); // Shortcut to top
1010 1011
1011 1012 // Now walk the current IfNode's projections.
1012 1013 // Loop ends when 'this' has no more uses.
1013 1014 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1014 1015 Node *ifp = last_out(i); // Get IfTrue/IfFalse
1015 1016 igvn->add_users_to_worklist(ifp);
1016 1017 // Check which projection it is and set target.
1017 1018 // Data-target is either the dominating projection of the same type
1018 1019 // or TOP if the dominating projection is of opposite type.
1019 1020 // Data-target will be used as the new control edge for the non-CFG
1020 1021 // nodes like Casts and Loads.
1021 1022 Node *data_target = (ifp->Opcode() == prev_op ) ? prev_dom : top;
1022 1023 // Control-target is just the If's immediate dominator or TOP.
1023 1024 Node *ctrl_target = (ifp->Opcode() == prev_op ) ? idom : top;
1024 1025
1025 1026 // For each child of an IfTrue/IfFalse projection, reroute.
1026 1027 // Loop ends when projection has no more uses.
1027 1028 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1028 1029 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1029 1030 igvn->hash_delete(s); // Yank from hash table before edge hacking
1030 1031 if( !s->depends_only_on_test() ) {
1031 1032 // Find the control input matching this def-use edge.
1032 1033 // For Regions it may not be in slot 0.
1033 1034 uint l;
1034 1035 for( l = 0; s->in(l) != ifp; l++ ) { }
1035 1036 s->set_req(l, ctrl_target);
1036 1037 } else { // Else, for control producers,
1037 1038 s->set_req(0, data_target); // Move child to data-target
1038 1039 }
1039 1040 igvn->_worklist.push(s); // Revisit collapsed Phis
1040 1041 } // End for each child of a projection
1041 1042
1042 1043 igvn->remove_dead_node(ifp);
1043 1044 } // End for each IfTrue/IfFalse child of If
1044 1045
1045 1046 // Kill the IfNode
1046 1047 igvn->remove_dead_node(this);
1047 1048 }
1048 1049
1049 1050 //------------------------------Identity---------------------------------------
1050 1051 // If the test is constant & we match, then we are the input Control
1051 1052 Node *IfTrueNode::Identity( PhaseTransform *phase ) {
1052 1053 // Can only optimize if cannot go the other way
1053 1054 const TypeTuple *t = phase->type(in(0))->is_tuple();
1054 1055 return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFTRUE )
1055 1056 ? in(0)->in(0) // IfNode control
1056 1057 : this; // no progress
1057 1058 }
1058 1059
1059 1060 //------------------------------dump_spec--------------------------------------
1060 1061 #ifndef PRODUCT
1061 1062 void IfNode::dump_spec(outputStream *st) const {
1062 1063 st->print("P=%f, C=%f",_prob,_fcnt);
1063 1064 }
1064 1065 #endif
1065 1066
1066 1067 //------------------------------idealize_test----------------------------------
1067 1068 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1068 1069 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1069 1070 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1070 1071 // needed.
1071 1072 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1072 1073 assert(iff->in(0) != NULL, "If must be live");
1073 1074
1074 1075 if (iff->outcnt() != 2) return NULL; // Malformed projections.
1075 1076 Node* old_if_f = iff->proj_out(false);
1076 1077 Node* old_if_t = iff->proj_out(true);
1077 1078
1078 1079 // CountedLoopEnds want the back-control test to be TRUE, irregardless of
1079 1080 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1080 1081 // happens in count-down loops
1081 1082 if (iff->is_CountedLoopEnd()) return NULL;
1082 1083 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests
1083 1084 BoolNode *b = iff->in(1)->as_Bool();
1084 1085 BoolTest bt = b->_test;
1085 1086 // Test already in good order?
1086 1087 if( bt.is_canonical() )
1087 1088 return NULL;
1088 1089
1089 1090 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1090 1091 // cloning the IfNode.
1091 1092 Node* new_b = phase->transform( new (phase->C, 2) BoolNode(b->in(1), bt.negate()) );
1092 1093 if( !new_b->is_Bool() ) return NULL;
1093 1094 b = new_b->as_Bool();
1094 1095
1095 1096 PhaseIterGVN *igvn = phase->is_IterGVN();
1096 1097 assert( igvn, "Test is not canonical in parser?" );
1097 1098
1098 1099 // The IF node never really changes, but it needs to be cloned
1099 1100 iff = new (phase->C, 2) IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt);
1100 1101
1101 1102 Node *prior = igvn->hash_find_insert(iff);
1102 1103 if( prior ) {
1103 1104 igvn->remove_dead_node(iff);
1104 1105 iff = (IfNode*)prior;
1105 1106 } else {
1106 1107 // Cannot call transform on it just yet
1107 1108 igvn->set_type_bottom(iff);
1108 1109 }
1109 1110 igvn->_worklist.push(iff);
1110 1111
1111 1112 // Now handle projections. Cloning not required.
1112 1113 Node* new_if_f = (Node*)(new (phase->C, 1) IfFalseNode( iff ));
1113 1114 Node* new_if_t = (Node*)(new (phase->C, 1) IfTrueNode ( iff ));
1114 1115
1115 1116 igvn->register_new_node_with_optimizer(new_if_f);
1116 1117 igvn->register_new_node_with_optimizer(new_if_t);
1117 1118 // Flip test, so flip trailing control
1118 1119 igvn->replace_node(old_if_f, new_if_t);
1119 1120 igvn->replace_node(old_if_t, new_if_f);
1120 1121
1121 1122 // Progress
1122 1123 return iff;
1123 1124 }
1124 1125
1125 1126 //------------------------------Identity---------------------------------------
1126 1127 // If the test is constant & we match, then we are the input Control
1127 1128 Node *IfFalseNode::Identity( PhaseTransform *phase ) {
1128 1129 // Can only optimize if cannot go the other way
1129 1130 const TypeTuple *t = phase->type(in(0))->is_tuple();
1130 1131 return ( t == TypeTuple::IFNEITHER || t == TypeTuple::IFFALSE )
1131 1132 ? in(0)->in(0) // IfNode control
1132 1133 : this; // no progress
1133 1134 }
|
↓ open down ↓ |
575 lines elided |
↑ open up ↑ |
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX