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* Copyright (c) 2000, 2023, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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* 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,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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#include "precompiled.hpp"
26
#include "ci/ciTypeFlow.hpp"
27
#include "memory/allocation.inline.hpp"
28
#include "memory/resourceArea.hpp"
29
#include "opto/addnode.hpp"
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#include "opto/castnode.hpp"
31
#include "opto/cfgnode.hpp"
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#include "opto/connode.hpp"
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#include "opto/loopnode.hpp"
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#include "opto/phaseX.hpp"
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#include "opto/predicates.hpp"
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#include "opto/runtime.hpp"
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#include "opto/rootnode.hpp"
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#include "opto/subnode.hpp"
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#include "opto/subtypenode.hpp"
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// Portions of code courtesy of Clifford Click
43
// Optimization - Graph Style
47
extern uint explicit_null_checks_elided;
50
IfNode::IfNode(Node* control, Node* bol, float p, float fcnt)
54
NOT_PRODUCT(COMMA _assertion_predicate_type(AssertionPredicateType::None)) {55
init_node(control, bol);
59
IfNode::IfNode(Node* control, Node* bol, float p, float fcnt, AssertionPredicateType assertion_predicate_type)
63
_assertion_predicate_type(assertion_predicate_type) {64
init_node(control, bol);
68
//=============================================================================
69
//------------------------------Value------------------------------------------
70
// Return a tuple for whichever arm of the IF is reachable
71
const Type* IfNode::Value(PhaseGVN* phase) const {72
if( !in(0) ) return Type::TOP;
73
if( phase->type(in(0)) == Type::TOP )
75
const Type *t = phase->type(in(1));
76
if( t == Type::TOP ) // data is undefined
77
return TypeTuple::IFNEITHER; // unreachable altogether
78
if( t == TypeInt::ZERO ) // zero, or false
79
return TypeTuple::IFFALSE; // only false branch is reachable
80
if( t == TypeInt::ONE ) // 1, or true
81
return TypeTuple::IFTRUE; // only true branch is reachable
82
assert( t == TypeInt::BOOL, "expected boolean type" );
84
return TypeTuple::IFBOTH; // No progress
87
const RegMask &IfNode::out_RegMask() const {88
return RegMask::Empty;
91
//------------------------------split_if---------------------------------------
92
// Look for places where we merge constants, then test on the merged value.
93
// If the IF test will be constant folded on the path with the constant, we
94
// win by splitting the IF to before the merge point.
95
static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {96
// I could be a lot more general here, but I'm trying to squeeze this
97
// in before the Christmas '98 break so I'm gonna be kinda restrictive
98
// on the patterns I accept. CNC
100
// Look for a compare of a constant and a merged value
101
Node *i1 = iff->in(1);
102
if( !i1->is_Bool() ) return nullptr;
103
BoolNode *b = i1->as_Bool();
104
Node *cmp = b->in(1);
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if( !cmp->is_Cmp() ) return nullptr;
107
if( i1 == nullptr || !i1->is_Phi() ) return nullptr;
108
PhiNode *phi = i1->as_Phi();
109
Node *con2 = cmp->in(2);
110
if( !con2->is_Con() ) return nullptr;
111
// See that the merge point contains some constants
114
RegionNode* phi_region = phi->region();
115
for (i4 = 1; i4 < phi->req(); i4++ ) {117
// Do not optimize partially collapsed merges
118
if (con1 == nullptr || phi_region->in(i4) == nullptr || igvn->type(phi_region->in(i4)) == Type::TOP) {119
igvn->_worklist.push(iff);
122
if( con1->is_Con() ) break; // Found a constant
123
// Also allow null-vs-not-null checks
124
const TypePtr *tp = igvn->type(con1)->isa_ptr();
125
if( tp && tp->_ptr == TypePtr::NotNull )
128
if( i4 >= phi->req() ) return nullptr; // Found no constants
130
igvn->C->set_has_split_ifs(true); // Has chance for split-if
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// Make sure that the compare can be constant folded away
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Node *cmp2 = cmp->clone();
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cmp2->set_req(1,con1);
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cmp2->set_req(2,con2);
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const Type *t = cmp2->Value(igvn);
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// This compare is dead, so whack it!
138
igvn->remove_dead_node(cmp2);
139
if( !t->singleton() ) return nullptr;
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// No intervening control, like a simple Call
142
Node* r = iff->in(0);
143
if (!r->is_Region() || r->is_Loop() || phi_region != r || r->as_Region()->is_copy()) {147
// No other users of the cmp/bool
148
if (b->outcnt() != 1 || cmp->outcnt() != 1) {149
//tty->print_cr("many users of cmp/bool");153
// Make sure we can determine where all the uses of merged values go
154
for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {155
Node* u = r->fast_out(j);
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if( u == r ) continue;
157
if( u == iff ) continue;
158
if( u->outcnt() == 0 ) continue; // use is dead & ignorable
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if( u->is_Start() ) {162
tty->print_cr("Region has inlined start use");164
tty->print_cr("Region has odd use");170
// CNC - do not allow any other merged value
171
//tty->print_cr("Merging another value");175
// Make sure we can account for all Phi uses
176
for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {177
Node* v = u->fast_out(k); // User of the phi
178
// CNC - Allow only really simple patterns.
179
// In particular I disallow AddP of the Phi, a fairly common pattern
180
if (v == cmp) continue; // The compare is OK
181
if (v->is_ConstraintCast()) {182
// If the cast is derived from data flow edges, it may not have a control edge.
183
// If so, it should be safe to split. But follow-up code can not deal with
184
// this (l. 359). So skip.
185
if (v->in(0) == nullptr) {188
if (v->in(0)->in(0) == iff) {189
continue; // CastPP/II of the IfNode is OK
192
// Disabled following code because I cannot tell if exactly one
193
// path dominates without a real dominator check. CNC 9/9/1999
194
//uint vop = v->Opcode();
195
//if( vop == Op_Phi ) { // Phi from another merge point might be OK196
// Node *r = v->in(0); // Get controlling point
197
// if( !r ) return nullptr; // Degraded to a copy
198
// // Find exactly one path in (either True or False doms, but not IFF)
200
// for( uint i = 1; i < r->req(); i++ )
201
// if( r->in(i) && r->in(i)->in(0) == iff )
203
// if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
205
if( !v->is_Call() ) {207
if( v->Opcode() == Op_AddP ) {208
tty->print_cr("Phi has AddP use");209
} else if( v->Opcode() == Op_CastPP ) {210
tty->print_cr("Phi has CastPP use");211
} else if( v->Opcode() == Op_CastII ) {212
tty->print_cr("Phi has CastII use");214
tty->print_cr("Phi has use I can't be bothered with");220
/* CNC - Cut out all the fancy acceptance tests
221
// Can we clone this use when doing the transformation?
222
// If all uses are from Phis at this merge or constants, then YES.
223
if( !v->in(0) && v != cmp ) {224
tty->print_cr("Phi has free-floating use");228
for( uint l = 1; l < v->req(); l++ ) {229
if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
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!v->in(l)->is_Con() ) {231
tty->print_cr("Phi has use");234
} // End of if Phi-use input is neither Phi nor Constant
235
} // End of for all inputs to Phi-use
237
} // End of for all uses of Phi
238
} // End of for all uses of Region
240
// Only do this if the IF node is in a sane state
241
if (iff->outcnt() != 2)
244
// Got a hit! Do the Mondo Hack!
246
//ABC a1c def ghi B 1 e h A C a c d f g i
247
// R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi
248
// cmp - 2 cmp - 2 cmp - 2
249
// bool bool_c bool_x
252
// ..s.. ..t .. ..s.. ..t.. ..s.. ..t..
254
// Split the paths coming into the merge point into 2 separate groups of
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// merges. On the left will be all the paths feeding constants into the
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// Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi
257
// will fold up into a constant; this will let the Cmp fold up as well as
258
// all the control flow. Below the original IF we have 2 control
259
// dependent regions, 's' and 't'. Now we will merge the two paths
260
// just prior to 's' and 't' from the two IFs. At least 1 path (and quite
261
// likely 2 or more) will promptly constant fold away.
262
PhaseGVN *phase = igvn;
264
// Make a region merging constants and a region merging the rest
266
for (uint ii = 1; ii < r->req(); ii++) {267
if (phi->in(ii) == con1) {270
if (Node::may_be_loop_entry(r->in(ii))) {271
// Bail out if splitting through a region with a Parse Predicate input (could
272
// also be a loop header before loop opts creates a LoopNode for it).
277
// If all the defs of the phi are the same constant, we already have the desired end state.
278
// Skip the split that would create empty phi and region nodes.
279
if ((r->req() - req_c) == 1) {283
// At this point we know that we can apply the split if optimization. If the region is still on the worklist,
284
// we should wait until it is processed. The region might be removed which makes this optimization redundant.
285
// This also avoids the creation of dead data loops when rewiring data nodes below when a region is dying.
286
if (igvn->_worklist.member(r)) {287
igvn->_worklist.push(iff); // retry split if later again
291
Node *region_c = new RegionNode(req_c + 1);
294
Node *region_x = new RegionNode(len - req_c);
295
Node *phi_x = PhiNode::make_blank(region_x, phi);
296
for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {297
if (phi->in(i) == con1) {298
region_c->init_req( i_c++, r ->in(i) );
300
region_x->init_req( i_x, r ->in(i) );
301
phi_x ->init_req( i_x++, phi->in(i) );
305
// Register the new RegionNodes but do not transform them. Cannot
306
// transform until the entire Region/Phi conglomerate has been hacked
307
// as a single huge transform.
308
igvn->register_new_node_with_optimizer( region_c );
309
igvn->register_new_node_with_optimizer( region_x );
310
// Prevent the untimely death of phi_x. Currently he has no uses. He is
311
// about to get one. If this only use goes away, then phi_x will look dead.
312
// However, he will be picking up some more uses down below.
313
Node *hook = new Node(4);
314
hook->init_req(0, phi_x);
315
hook->init_req(1, phi_c);
316
phi_x = phase->transform( phi_x );
319
Node *cmp_c = phase->makecon(t);
320
Node *cmp_x = cmp->clone();
321
cmp_x->set_req(1,phi_x);
322
cmp_x->set_req(2,con2);
323
cmp_x = phase->transform(cmp_x);
325
Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
326
Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
328
IfNode* iff_c = iff->clone()->as_If();
329
iff_c->set_req(0, region_c);
330
iff_c->set_req(1, b_c);
331
igvn->set_type_bottom(iff_c);
332
igvn->_worklist.push(iff_c);
333
hook->init_req(2, iff_c);
335
IfNode* iff_x = iff->clone()->as_If();
336
iff_x->set_req(0, region_x);
337
iff_x->set_req(1, b_x);
338
igvn->set_type_bottom(iff_x);
339
igvn->_worklist.push(iff_x);
340
hook->init_req(3, iff_x);
342
// Make the true/false arms
343
Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
344
Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
345
Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
346
Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
348
// Merge the TRUE paths
349
Node *region_s = new RegionNode(3);
350
igvn->_worklist.push(region_s);
351
region_s->init_req(1, iff_c_t);
352
region_s->init_req(2, iff_x_t);
353
igvn->register_new_node_with_optimizer( region_s );
355
// Merge the FALSE paths
356
Node *region_f = new RegionNode(3);
357
igvn->_worklist.push(region_f);
358
region_f->init_req(1, iff_c_f);
359
region_f->init_req(2, iff_x_f);
360
igvn->register_new_node_with_optimizer( region_f );
362
igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
363
cmp->set_req(1,nullptr); // Whack the inputs to cmp because it will be dead
364
cmp->set_req(2,nullptr);
365
// Check for all uses of the Phi and give them a new home.
366
// The 'cmp' got cloned, but CastPP/IIs need to be moved.
367
Node *phi_s = nullptr; // do not construct unless needed
368
Node *phi_f = nullptr; // do not construct unless needed
369
for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {370
Node* v = phi->last_out(i2);// User of the phi
371
igvn->rehash_node_delayed(v); // Have to fixup other Phi users
372
uint vop = v->Opcode();
373
Node *proj = nullptr;
374
if( vop == Op_Phi ) { // Remote merge point376
for (uint i3 = 1; i3 < r->req(); i3++)
377
if (r->in(i3) && r->in(i3)->in(0) == iff) {381
} else if( v->is_ConstraintCast() ) {382
proj = v->in(0); // Controlling projection
384
assert( 0, "do not know how to handle this guy" );
386
guarantee(proj != nullptr, "sanity");
388
Node *proj_path_data, *proj_path_ctrl;
389
if( proj->Opcode() == Op_IfTrue ) {390
if( phi_s == nullptr ) {391
// Only construct phi_s if needed, otherwise provides
393
phi_s = PhiNode::make_blank(region_s,phi);
394
phi_s->init_req( 1, phi_c );
395
phi_s->init_req( 2, phi_x );
396
hook->add_req(phi_s);
397
phi_s = phase->transform(phi_s);
399
proj_path_data = phi_s;
400
proj_path_ctrl = region_s;
402
if( phi_f == nullptr ) {403
// Only construct phi_f if needed, otherwise provides
405
phi_f = PhiNode::make_blank(region_f,phi);
406
phi_f->init_req( 1, phi_c );
407
phi_f->init_req( 2, phi_x );
408
hook->add_req(phi_f);
409
phi_f = phase->transform(phi_f);
411
proj_path_data = phi_f;
412
proj_path_ctrl = region_f;
415
// Fixup 'v' for for the split
416
if( vop == Op_Phi ) { // Remote merge point418
for( i = 1; i < v->req(); i++ )
419
if( v->in(i) == phi )
421
v->set_req(i, proj_path_data );
422
} else if( v->is_ConstraintCast() ) {423
v->set_req(0, proj_path_ctrl );
424
v->set_req(1, proj_path_data );
426
ShouldNotReachHere();
429
// Now replace the original iff's True/False with region_s/region_t.
430
// This makes the original iff go dead.
431
for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {432
Node* p = iff->last_out(i3);
433
assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
434
Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
436
igvn->add_users_to_worklist(p);
437
for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {438
Node* x = p->last_out(l);
439
igvn->hash_delete(x);
441
for( uint j = 0; j < x->req(); j++ ) {442
if( x->in(j) == p ) {447
l -= uses_found; // we deleted 1 or more copies of this edge
449
igvn->remove_dead_node(p);
452
// Force the original merge dead
453
igvn->hash_delete(r);
454
// First, remove region's dead users.
455
for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {456
Node* u = r->last_out(l);
458
r->set_req(0, nullptr);
460
assert(u->outcnt() == 0, "only dead users");
461
igvn->remove_dead_node(u);
465
igvn->remove_dead_node(r);
467
// Now remove the bogus extra edges used to keep things alive
468
igvn->remove_dead_node( hook );
470
// Must return either the original node (now dead) or a new node
471
// (Do not return a top here, since that would break the uniqueness of top.)
472
return new ConINode(TypeInt::ZERO);
475
IfNode* IfNode::make_with_same_profile(IfNode* if_node_profile, Node* ctrl, BoolNode* bol) {476
// Assert here that we only try to create a clone from an If node with the same profiling if that actually makes sense.
477
// Some If node subtypes should not be cloned in this way. In theory, we should not clone BaseCountedLoopEndNodes.
478
// But they can end up being used as normal If nodes when peeling a loop - they serve as zero-trip guard.
479
// Allow them as well.
480
assert(if_node_profile->Opcode() == Op_If || if_node_profile->is_RangeCheck()
481
|| if_node_profile->is_BaseCountedLoopEnd(), "should not clone other nodes");
482
if (if_node_profile->is_RangeCheck()) {483
// RangeCheck nodes could be further optimized.
484
return new RangeCheckNode(ctrl, bol, if_node_profile->_prob, if_node_profile->_fcnt);
486
// Not a RangeCheckNode? Fall back to IfNode.
487
return new IfNode(ctrl, bol, if_node_profile->_prob, if_node_profile->_fcnt);
491
// if this IfNode follows a range check pattern return the projection
492
// for the failed path
493
ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {498
if (b == nullptr || !b->is_Bool()) return nullptr;
499
BoolNode* bn = b->as_Bool();
500
Node* cmp = bn->in(1);
501
if (cmp == nullptr) return nullptr;
502
if (cmp->Opcode() != Op_CmpU) return nullptr;
507
if (bn->_test._test == BoolTest::le) {511
} else if (bn->_test._test != BoolTest::lt) {514
if (l->is_top()) return nullptr; // Top input means dead test
515
if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return nullptr;
517
// We have recognized one of these forms:
518
// Flip 1: If (Bool[<] CmpU(l, LoadRange)) ...
519
// Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ...
521
ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
526
//------------------------------is_range_check---------------------------------
527
// Return 0 if not a range check. Return 1 if a range check and set index and
528
// offset. Return 2 if we had to negate the test. Index is null if the check
529
// is versus a constant.
530
int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {534
ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
536
if (iftrap == nullptr) {540
// Make sure it's a real range check by requiring an uncommon trap
541
// along the OOB path. Otherwise, it's possible that the user wrote
542
// something which optimized to look like a range check but behaves
543
// in some other way.
544
if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == nullptr) {548
// Look for index+offset form
553
} else if (l->Opcode() == Op_AddI) {554
if ((off = l->in(1)->find_int_con(0)) != 0) {555
ind = l->in(2)->uncast();
556
} else if ((off = l->in(2)->find_int_con(0)) != 0) {557
ind = l->in(1)->uncast();
559
} else if ((off = l->find_int_con(-1)) >= 0) {560
// constant offset with no variable index
563
// variable index with no constant offset (or dead negative index)
567
// Return all the values:
574
//------------------------------adjust_check-----------------------------------
575
// Adjust (widen) a prior range check
576
static void adjust_check(IfProjNode* proj, Node* range, Node* index,
577
int flip, jint off_lo, PhaseIterGVN* igvn) {578
PhaseGVN *gvn = igvn;
579
// Break apart the old check
580
Node *iff = proj->in(0);
581
Node *bol = iff->in(1);
582
if( bol->is_top() ) return; // In case a partially dead range check appears
583
// bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
584
DEBUG_ONLY( if (!bol->is_Bool()) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )585
if (!bol->is_Bool()) return;
587
Node *cmp = bol->in(1);
588
// Compute a new check
589
Node *new_add = gvn->intcon(off_lo);
591
new_add = off_lo ? gvn->transform(new AddINode(index, new_add)) : index;
593
Node *new_cmp = (flip == 1)
594
? new CmpUNode(new_add, range)
595
: new CmpUNode(range, new_add);
596
new_cmp = gvn->transform(new_cmp);
597
// See if no need to adjust the existing check
598
if (new_cmp == cmp) return;
599
// Else, adjust existing check
600
Node* new_bol = gvn->transform(new BoolNode(new_cmp, bol->as_Bool()->_test._test));
601
igvn->rehash_node_delayed(iff);
602
iff->set_req_X(1, new_bol, igvn);
603
// As part of range check smearing, this range check is widened. Loads and range check Cast nodes that are control
604
// dependent on this range check now depend on multiple dominating range checks. These control dependent nodes end up
605
// at the lowest/nearest dominating check in the graph. To ensure that these Loads/Casts do not float above any of the
606
// dominating checks (even when the lowest dominating check is later replaced by yet another dominating check), we
607
// need to pin them at the lowest dominating check.
608
proj->pin_array_access_nodes(igvn);
611
//------------------------------up_one_dom-------------------------------------
612
// Walk up the dominator tree one step. Return null at root or true
613
// complex merges. Skips through small diamonds.
614
Node* IfNode::up_one_dom(Node *curr, bool linear_only) {615
Node *dom = curr->in(0);
616
if( !dom ) // Found a Region degraded to a copy?
617
return curr->nonnull_req(); // Skip thru it
619
if( curr != dom ) // Normal walk up one step?
622
// Use linear_only if we are still parsing, since we cannot
623
// trust the regions to be fully filled in.
630
// Else hit a Region. Check for a loop header
632
return dom->in(1); // Skip up thru loops
634
// Check for small diamonds
635
Node *din1, *din2, *din3, *din4;
636
if( dom->req() == 3 && // 2-path merge point
637
(din1 = dom ->in(1)) && // Left path exists
638
(din2 = dom ->in(2)) && // Right path exists
639
(din3 = din1->in(0)) && // Left path up one
640
(din4 = din2->in(0)) ) { // Right path up one641
if( din3->is_Call() && // Handle a slow-path call on either arm
642
(din3 = din3->in(0)) )
644
if( din4->is_Call() && // Handle a slow-path call on either arm
645
(din4 = din4->in(0)) )
647
if (din3 != nullptr && din3 == din4 && din3->is_If()) // Regions not degraded to a copy
648
return din3; // Skip around diamonds
651
// Give up the search at true merges
652
return nullptr; // Dead loop? Or hit root?
656
//------------------------------filtered_int_type--------------------------------
657
// Return a possibly more restrictive type for val based on condition control flow for an if
658
const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node* val, Node* if_proj) {660
(if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
661
if (if_proj->in(0) && if_proj->in(0)->is_If()) {662
IfNode* iff = if_proj->in(0)->as_If();
663
if (iff->in(1) && iff->in(1)->is_Bool()) {664
BoolNode* bol = iff->in(1)->as_Bool();
665
if (bol->in(1) && bol->in(1)->is_Cmp()) {666
const CmpNode* cmp = bol->in(1)->as_Cmp();
667
if (cmp->in(1) == val) {668
const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
669
if (cmp2_t != nullptr) {670
jint lo = cmp2_t->_lo;
671
jint hi = cmp2_t->_hi;
672
BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
675
// If val is compared to its lower or upper bound, we can narrow the type
676
const TypeInt* val_t = gvn->type(val)->isa_int();
677
if (val_t != nullptr && !val_t->singleton() && cmp2_t->is_con()) {678
if (val_t->_lo == lo) {679
return TypeInt::make(val_t->_lo + 1, val_t->_hi, val_t->_widen);
680
} else if (val_t->_hi == hi) {681
return TypeInt::make(val_t->_lo, val_t->_hi - 1, val_t->_widen);
690
lo = TypeInt::INT->_lo;
691
if (hi != min_jint) {696
lo = TypeInt::INT->_lo;
699
if (lo != max_jint) {702
hi = TypeInt::INT->_hi;
706
hi = TypeInt::INT->_hi;
711
const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
721
//------------------------------fold_compares----------------------------
722
// See if a pair of CmpIs can be converted into a CmpU. In some cases
723
// the direction of this if is determined by the preceding if so it
724
// can be eliminate entirely.
726
// Given an if testing (CmpI n v) check for an immediately control
727
// dependent if that is testing (CmpI n v2) and has one projection
728
// leading to this if and the other projection leading to a region
729
// that merges one of this ifs control projections.
741
// Or given an if testing (CmpI n v) check for a dominating if that is
742
// testing (CmpI n v2), both having one projection leading to an
743
// uncommon trap. Allow Another independent guard in between to cover
744
// an explicit range check:
745
// if (index < 0 || index >= array.length) {746
// which may need a null check to guard the LoadRange
759
// Is the comparison for this If suitable for folding?
760
bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {761
return in(1) != nullptr &&
763
in(1)->in(1) != nullptr &&
764
in(1)->in(1)->Opcode() == Op_CmpI &&
765
in(1)->in(1)->in(2) != nullptr &&
766
in(1)->in(1)->in(2) != igvn->C->top() &&
767
(in(1)->as_Bool()->_test.is_less() ||
768
in(1)->as_Bool()->_test.is_greater() ||
769
(fold_ne && in(1)->as_Bool()->_test._test == BoolTest::ne));
772
// Is a dominating control suitable for folding with this if?
773
bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {774
return ctrl != nullptr &&
776
ctrl->outcnt() == 1 && // No side-effects
777
ctrl->in(0) != nullptr &&
778
ctrl->in(0)->Opcode() == Op_If &&
779
ctrl->in(0)->outcnt() == 2 &&
780
ctrl->in(0)->as_If()->cmpi_folds(igvn, true) &&
781
// Must compare same value
782
ctrl->in(0)->in(1)->in(1)->in(1) != nullptr &&
783
ctrl->in(0)->in(1)->in(1)->in(1) != igvn->C->top() &&
784
ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
787
// Do this If and the dominating If share a region?
788
bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {789
ProjNode* otherproj = proj->other_if_proj();
790
Node* otherproj_ctrl_use = otherproj->unique_ctrl_out_or_null();
791
RegionNode* region = (otherproj_ctrl_use != nullptr && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : nullptr;
795
if (otherproj->outcnt() == 1 && region != nullptr && !region->has_phi()) {796
for (int i = 0; i < 2; i++) {797
ProjNode* proj = proj_out(i);
798
if (success == nullptr && proj->outcnt() == 1 && proj->unique_out() == region) {800
} else if (fail == nullptr) {803
success = fail = nullptr;
807
return success != nullptr && fail != nullptr;
810
bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) {811
// Different methods and methods containing jsrs are not supported.
812
ciMethod* method = unc->jvms()->method();
813
ciMethod* dom_method = dom_unc->jvms()->method();
814
if (method != dom_method || method->has_jsrs()) {817
// Check that both traps are in the same activation of the method (instead
818
// of two activations being inlined through different call sites) by verifying
819
// that the call stacks are equal for both JVMStates.
820
JVMState* dom_caller = dom_unc->jvms()->caller();
821
JVMState* caller = unc->jvms()->caller();
822
if ((dom_caller == nullptr) != (caller == nullptr)) {823
// The current method must either be inlined into both dom_caller and
824
// caller or must not be inlined at all (top method). Bail out otherwise.
826
} else if (dom_caller != nullptr && !dom_caller->same_calls_as(caller)) {829
// Check that the bci of the dominating uncommon trap dominates the bci
830
// of the dominated uncommon trap. Otherwise we may not re-execute
831
// the dominated check after deoptimization from the merged uncommon trap.
832
ciTypeFlow* flow = dom_method->get_flow_analysis();
833
int bci = unc->jvms()->bci();
834
int dom_bci = dom_unc->jvms()->bci();
835
if (!flow->is_dominated_by(bci, dom_bci)) {842
// Return projection that leads to an uncommon trap if any
843
ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {844
for (int i = 0; i < 2; i++) {845
call = proj_out(i)->is_uncommon_trap_proj();
846
if (call != nullptr) {853
// Do this If and the dominating If both branch out to an uncommon trap
854
bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {855
ProjNode* otherproj = proj->other_if_proj();
856
CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj();
858
if (otherproj->outcnt() == 1 && dom_unc != nullptr) {859
// We need to re-execute the folded Ifs after deoptimization from the merged traps
860
if (!dom_unc->jvms()->should_reexecute()) {864
CallStaticJavaNode* unc = nullptr;
865
ProjNode* unc_proj = uncommon_trap_proj(unc);
866
if (unc_proj != nullptr && unc_proj->outcnt() == 1) {867
if (dom_unc == unc) {868
// Allow the uncommon trap to be shared through a region
869
RegionNode* r = unc->in(0)->as_Region();
870
if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {873
assert(r->has_phi() == nullptr, "simple region shouldn't have a phi");
874
} else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {878
if (!is_dominator_unc(dom_unc, unc)) {882
// See merge_uncommon_traps: the reason of the uncommon trap
883
// will be changed and the state of the dominating If will be
884
// used. Checked that we didn't apply this transformation in a
885
// previous compilation and it didn't cause too many traps
886
ciMethod* dom_method = dom_unc->jvms()->method();
887
int dom_bci = dom_unc->jvms()->bci();
888
if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
889
!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check) &&
890
// Return true if c2 manages to reconcile with UnstableIf optimization. See the comments for it.
891
igvn->C->remove_unstable_if_trap(dom_unc, true/*yield*/)) {893
fail = unc_proj->other_if_proj();
901
// Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
902
bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {903
Node* this_cmp = in(1)->in(1);
904
BoolNode* this_bool = in(1)->as_Bool();
905
IfNode* dom_iff = proj->in(0)->as_If();
906
BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
907
Node* lo = dom_iff->in(1)->in(1)->in(2);
908
Node* hi = this_cmp->in(2);
909
Node* n = this_cmp->in(1);
910
ProjNode* otherproj = proj->other_if_proj();
912
const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
913
const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
915
BoolTest::mask lo_test = dom_bool->_test._test;
916
BoolTest::mask hi_test = this_bool->_test._test;
917
BoolTest::mask cond = hi_test;
921
// dom_bool = x {<,<=,>,>=} a923
// proj = {True,False} / \ otherproj = {False,True}925
// this_bool = x {<,<=} b927
// fail = {True,False} / \ success = {False,True}930
// (Second test guaranteed canonicalized, first one may not have
931
// been canonicalized yet)
935
// cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim941
// Figure out which of the two tests sets the upper bound and which
942
// sets the lower bound if any.
943
Node* adjusted_lim = nullptr;
944
if (lo_type != nullptr && hi_type != nullptr && hi_type->_lo > lo_type->_hi &&
945
hi_type->_hi == max_jint && lo_type->_lo == min_jint && lo_test != BoolTest::ne) {946
assert((dom_bool->_test.is_less() && !proj->_con) ||
947
(dom_bool->_test.is_greater() && proj->_con), "incorrect test");
950
// dom_bool = >= (proj = True) or dom_bool = < (proj = False)
951
// x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
952
// lo = a, hi = b, adjusted_lim = b-a, cond = <u
953
// dom_bool = > (proj = True) or dom_bool = <= (proj = False)
954
// x in ]a, b[ on the fail (= True) projection, b > a:
955
// lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
957
// dom_bool = >= (proj = True) or dom_bool = < (proj = False)
958
// x in [a, b] on the fail (= True) projection, b+1 > a-1:
959
// lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
960
// lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
961
// dom_bool = > (proj = True) or dom_bool = <= (proj = False)
962
// x in ]a, b] on the fail (= True) projection b+1 > a:
963
// lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
964
// lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then b-a-1 = -1
966
if (hi_test == BoolTest::lt) {967
if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {968
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
970
} else if (hi_test == BoolTest::le) {971
if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {972
adjusted_lim = igvn->transform(new SubINode(hi, lo));
973
adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
975
} else if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {976
adjusted_lim = igvn->transform(new SubINode(hi, lo));
977
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
980
assert(false, "unhandled lo_test: %d", lo_test);
984
assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled hi_test: %d", hi_test);
987
// this test was canonicalized
988
assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
989
} else if (lo_type != nullptr && hi_type != nullptr && lo_type->_lo > hi_type->_hi &&
990
lo_type->_hi == max_jint && hi_type->_lo == min_jint && lo_test != BoolTest::ne) {993
// dom_bool = < (proj = True) or dom_bool = >= (proj = False)
994
// x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
995
// lo = b, hi = a, adjusted_lim = a-b, cond = >=u
996
// dom_bool = <= (proj = True) or dom_bool = > (proj = False)
997
// x in [b, a] on the fail (= False) projection, a+1 > b-1:
998
// lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
999
// lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
1001
// dom_bool = < (proj = True) or dom_bool = >= (proj = False)
1002
// x in ]b, a[ on the fail (= False) projection, a > b:
1003
// lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
1004
// dom_bool = <= (proj = True) or dom_bool = > (proj = False)
1005
// x in ]b, a] on the fail (= False) projection, a+1 > b:
1006
// lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
1007
// lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then b-a-1 = -1
1010
swap(lo_type, hi_type);
1011
swap(lo_test, hi_test);
1013
assert((dom_bool->_test.is_less() && proj->_con) ||
1014
(dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
1016
cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
1018
if (lo_test == BoolTest::lt) {1019
if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {1020
cond = BoolTest::ge;
1021
} else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {1022
adjusted_lim = igvn->transform(new SubINode(hi, lo));
1023
adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
1024
cond = BoolTest::ge;
1026
assert(false, "unhandled hi_test: %d", hi_test);
1029
} else if (lo_test == BoolTest::le) {1030
if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {1031
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1032
cond = BoolTest::ge;
1033
} else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {1034
adjusted_lim = igvn->transform(new SubINode(hi, lo));
1035
lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1036
cond = BoolTest::ge;
1038
assert(false, "unhandled hi_test: %d", hi_test);
1042
assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled lo_test: %d", lo_test);
1045
// this test was canonicalized
1046
assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
1048
const TypeInt* failtype = filtered_int_type(igvn, n, proj);
1049
if (failtype != nullptr) {1050
const TypeInt* type2 = filtered_int_type(igvn, n, fail);
1051
if (type2 != nullptr) {1052
failtype = failtype->join(type2)->is_int();
1053
if (failtype->empty()) {1054
// previous if determines the result of this if so
1055
// replace Bool with constant
1056
igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
1064
assert(lo != nullptr && hi != nullptr, "sanity");
1065
Node* hook = new Node(lo); // Add a use to lo to prevent him from dying
1066
// Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
1067
Node* adjusted_val = igvn->transform(new SubINode(n, lo));
1068
if (adjusted_lim == nullptr) {1069
adjusted_lim = igvn->transform(new SubINode(hi, lo));
1071
hook->destruct(igvn);
1073
if (adjusted_val->is_top() || adjusted_lim->is_top()) {1077
if (igvn->type(adjusted_lim)->is_int()->_lo < 0 &&
1078
!igvn->C->post_loop_opts_phase()) {1079
// If range check elimination applies to this comparison, it includes code to protect from overflows that may
1080
// cause the main loop to be skipped entirely. Delay this transformation.
1082
// for (int i = 0; i < limit; i++) {1083
// if (i < max_jint && i > min_jint) {...1085
// Comparisons folded as:
1086
// i - min_jint - 1 <u -2
1087
// when RC applies, main loop limit becomes:
1088
// min(limit, max(-2 + min_jint + 1, min_jint))
1089
// = min(limit, min_jint)
1091
if (adjusted_val->outcnt() == 0) {1092
igvn->remove_dead_node(adjusted_val);
1094
if (adjusted_lim->outcnt() == 0) {1095
igvn->remove_dead_node(adjusted_lim);
1097
igvn->C->record_for_post_loop_opts_igvn(this);
1101
Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
1102
Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
1104
igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
1105
igvn->replace_input_of(this, 1, newbool);
1110
// Merge the branches that trap for this If and the dominating If into
1111
// a single region that branches to the uncommon trap for the
1113
Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {1115
assert(success->in(0) == this, "bad projection");
1117
ProjNode* otherproj = proj->other_if_proj();
1119
CallStaticJavaNode* unc = success->is_uncommon_trap_proj();
1120
CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj();
1122
if (unc != dom_unc) {1123
Node* r = new RegionNode(3);
1125
r->set_req(1, otherproj);
1126
r->set_req(2, success);
1127
r = igvn->transform(r);
1128
assert(r->is_Region(), "can't go away");
1130
// Make both If trap at the state of the first If: once the CmpI
1131
// nodes are merged, if we trap we don't know which of the CmpI
1132
// nodes would have caused the trap so we have to restart
1133
// execution at the first one
1134
igvn->replace_input_of(dom_unc, 0, r);
1135
igvn->replace_input_of(unc, 0, igvn->C->top());
1137
int trap_request = dom_unc->uncommon_trap_request();
1138
Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1139
Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1145
if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != nullptr) {1146
// If this looks like a range check, change the trap to
1147
// Reason_range_check so the compiler recognizes it as a range
1148
// check and applies the corresponding optimizations
1149
trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1151
improve_address_types(l, r, fail, igvn);
1153
res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
1154
} else if (unc != dom_unc) {1155
// If we trap we won't know what CmpI would have caused the trap
1156
// so use a special trap reason to mark this pair of CmpI nodes as
1157
// bad candidate for folding. On recompilation we won't fold them
1158
// and we may trap again but this time we'll know what branch
1160
trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1162
igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1166
// If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1167
// of a rangecheck on index i, on 64 bit the compares may be followed
1168
// by memory accesses using i as index. In that case, the CmpU tells
1169
// us something about the values taken by i that can help the compiler
1170
// (see Compile::conv_I2X_index())
1171
void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {1174
Node_Stack stack(2);
1176
assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1177
const TypeInt* array_size = igvn->type(r)->is_int();
1181
while(stack.size() > 0) {1182
Node* n = stack.node();
1183
uint start = stack.index();
1186
for (; i < n->outcnt(); i++) {1187
Node* use = n->raw_out(i);
1188
if (stack.size() == 1) {1189
if (use->Opcode() == Op_ConvI2L) {1190
const TypeLong* bounds = use->as_Type()->type()->is_long();
1191
if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1192
(bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {1193
stack.set_index(i+1);
1198
} else if (use->is_Mem()) {1199
Node* ctrl = use->in(0);
1200
for (int i = 0; i < 10 && ctrl != nullptr && ctrl != fail; i++) {1201
ctrl = up_one_dom(ctrl);
1204
Node* init_n = stack.node_at(1);
1205
assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1206
// Create a new narrow ConvI2L node that is dependent on the range check
1207
Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
1209
// The type of the ConvI2L may be widen and so the new
1210
// ConvI2L may not be better than an existing ConvI2L
1211
if (new_n != init_n) {1212
for (uint j = 2; j < stack.size(); j++) {1213
Node* n = stack.node_at(j);
1214
Node* clone = n->clone();
1215
int rep = clone->replace_edge(init_n, new_n, igvn);
1216
assert(rep > 0, "can't find expected node?");
1217
clone = igvn->transform(clone);
1221
igvn->hash_delete(use);
1222
int rep = use->replace_edge(init_n, new_n, igvn);
1223
assert(rep > 0, "can't find expected node?");
1224
igvn->transform(use);
1225
if (init_n->outcnt() == 0) {1226
igvn->_worklist.push(init_n);
1230
} else if (use->in(0) == nullptr && (igvn->type(use)->isa_long() ||
1231
igvn->type(use)->isa_ptr())) {1232
stack.set_index(i+1);
1237
if (i == n->outcnt()) {1244
bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {1245
if (in(1) != nullptr &&
1246
in(1)->in(1) != nullptr &&
1247
in(1)->in(1)->in(2) != nullptr) {1248
Node* other = in(1)->in(1)->in(2);
1249
if (other->Opcode() == Op_LoadRange &&
1250
((other->in(0) != nullptr && other->in(0) == proj) ||
1251
(other->in(0) == nullptr &&
1252
other->in(2) != nullptr &&
1253
other->in(2)->is_AddP() &&
1254
other->in(2)->in(1) != nullptr &&
1255
other->in(2)->in(1)->Opcode() == Op_CastPP &&
1256
other->in(2)->in(1)->in(0) == proj))) {1263
bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {1264
Node* other = in(1)->in(1)->in(2);
1265
if (other->in(MemNode::Address) != nullptr &&
1266
proj->in(0)->in(1) != nullptr &&
1267
proj->in(0)->in(1)->is_Bool() &&
1268
proj->in(0)->in(1)->in(1) != nullptr &&
1269
proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1270
proj->in(0)->in(1)->in(1)->in(2) != nullptr &&
1271
proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1272
igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {1278
// Check that the If that is in between the 2 integer comparisons has
1280
bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {1281
if (proj == nullptr) {1284
CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1285
if (unc != nullptr && proj->outcnt() <= 2) {1286
if (proj->outcnt() == 1 ||
1287
// Allow simple null check from LoadRange
1288
(is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {1289
CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1290
CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern();
1291
assert(dom_unc != nullptr, "is_uncommon_trap_if_pattern returned null");
1293
// reroute_side_effect_free_unc changes the state of this
1294
// uncommon trap to restart execution at the previous
1295
// CmpI. Check that this change in a previous compilation didn't
1296
// cause too many traps.
1297
int trap_request = unc->uncommon_trap_request();
1298
Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1300
if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {1304
if (!is_dominator_unc(dom_unc, unc)) {1314
// Make the If between the 2 integer comparisons trap at the state of
1315
// the first If: the last CmpI is the one replaced by a CmpU and the
1316
// first CmpI is eliminated, so the test between the 2 CmpI nodes
1317
// won't be guarded by the first CmpI anymore. It can trap in cases
1318
// where the first CmpI would have prevented it from executing: on a
1319
// trap, we need to restart execution at the state of the first CmpI
1320
void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {1321
CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern();
1322
ProjNode* otherproj = proj->other_if_proj();
1323
CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1324
Node* call_proj = dom_unc->unique_ctrl_out();
1325
Node* halt = call_proj->unique_ctrl_out();
1327
Node* new_unc = dom_unc->clone();
1328
call_proj = call_proj->clone();
1329
halt = halt->clone();
1330
Node* c = otherproj->clone();
1332
c = igvn->transform(c);
1333
new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1334
new_unc->set_req(0, c);
1335
new_unc = igvn->transform(new_unc);
1336
call_proj->set_req(0, new_unc);
1337
call_proj = igvn->transform(call_proj);
1338
halt->set_req(0, call_proj);
1339
halt = igvn->transform(halt);
1341
igvn->replace_node(otherproj, igvn->C->top());
1342
igvn->C->root()->add_req(halt);
1345
Node* IfNode::fold_compares(PhaseIterGVN* igvn) {1346
if (Opcode() != Op_If) return nullptr;
1348
if (cmpi_folds(igvn)) {1350
if (is_ctrl_folds(ctrl, igvn)) {1351
// A integer comparison immediately dominated by another integer
1353
ProjNode* success = nullptr;
1354
ProjNode* fail = nullptr;
1355
ProjNode* dom_cmp = ctrl->as_Proj();
1356
if (has_shared_region(dom_cmp, success, fail) &&
1357
// Next call modifies graph so must be last
1358
fold_compares_helper(dom_cmp, success, fail, igvn)) {1361
if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1362
// Next call modifies graph so must be last
1363
fold_compares_helper(dom_cmp, success, fail, igvn)) {1364
return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1367
} else if (ctrl->in(0) != nullptr &&
1368
ctrl->in(0)->in(0) != nullptr) {1369
ProjNode* success = nullptr;
1370
ProjNode* fail = nullptr;
1371
Node* dom = ctrl->in(0)->in(0);
1372
ProjNode* dom_cmp = dom->isa_Proj();
1373
ProjNode* other_cmp = ctrl->isa_Proj();
1375
// Check if it's an integer comparison dominated by another
1376
// integer comparison with another test in between
1377
if (is_ctrl_folds(dom, igvn) &&
1378
has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1379
is_side_effect_free_test(other_cmp, igvn) &&
1380
// Next call modifies graph so must be last
1381
fold_compares_helper(dom_cmp, success, fail, igvn)) {1382
reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1383
return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1390
//------------------------------remove_useless_bool----------------------------
1391
// Check for people making a useless boolean: things like
1392
// if( (x < y ? true : false) ) { ... }1393
// Replace with if( x < y ) { ... }1394
static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {1395
Node *i1 = iff->in(1);
1396
if( !i1->is_Bool() ) return nullptr;
1397
BoolNode *bol = i1->as_Bool();
1399
Node *cmp = bol->in(1);
1400
if( cmp->Opcode() != Op_CmpI ) return nullptr;
1402
// Must be comparing against a bool
1403
const Type *cmp2_t = phase->type( cmp->in(2) );
1404
if( cmp2_t != TypeInt::ZERO &&
1405
cmp2_t != TypeInt::ONE )
1408
// Find a prior merge point merging the boolean
1410
if( !i1->is_Phi() ) return nullptr;
1411
PhiNode *phi = i1->as_Phi();
1412
if( phase->type( phi ) != TypeInt::BOOL )
1415
// Check for diamond pattern
1416
int true_path = phi->is_diamond_phi();
1417
if( true_path == 0 ) return nullptr;
1419
// Make sure that iff and the control of the phi are different. This
1420
// should really only happen for dead control flow since it requires
1421
// an illegal cycle.
1422
if (phi->in(0)->in(1)->in(0) == iff) return nullptr;
1424
// phi->region->if_proj->ifnode->bool->cmp
1425
BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1427
// Now get the 'sense' of the test correct so we can plug in
1428
// either iff2->in(1) or its complement.
1430
if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1431
else if( bol->_test._test != BoolTest::eq ) return nullptr;
1432
if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1434
const Type *phi1_t = phase->type( phi->in(1) );
1435
const Type *phi2_t = phase->type( phi->in(2) );
1436
// Check for Phi(0,1) and flip
1437
if( phi1_t == TypeInt::ZERO ) {1438
if( phi2_t != TypeInt::ONE ) return nullptr;
1441
// Check for Phi(1,0)
1442
if( phi1_t != TypeInt::ONE ) return nullptr;
1443
if( phi2_t != TypeInt::ZERO ) return nullptr;
1445
if( true_path == 2 ) {1449
Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1450
assert(new_bol != iff->in(1), "must make progress");
1451
iff->set_req_X(1, new_bol, phase);
1452
// Intervening diamond probably goes dead
1453
phase->C->set_major_progress();
1457
static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1464
Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {1465
if (remove_dead_region(phase, can_reshape)) return this;
1467
if (!can_reshape) return nullptr;
1469
// Don't bother trying to transform a dead if
1470
if (in(0)->is_top()) return nullptr;
1471
// Don't bother trying to transform an if with a dead test
1472
if (in(1)->is_top()) return nullptr;
1473
// Another variation of a dead test
1474
if (in(1)->is_Con()) return nullptr;
1475
// Another variation of a dead if
1476
if (outcnt() < 2) return nullptr;
1478
// Canonicalize the test.
1479
Node* idt_if = idealize_test(phase, this);
1480
if (idt_if != nullptr) return idt_if;
1482
// Try to split the IF
1483
PhaseIterGVN *igvn = phase->is_IterGVN();
1484
Node *s = split_if(this, igvn);
1485
if (s != nullptr) return s;
1487
return NodeSentinel;
1490
//------------------------------Ideal------------------------------------------
1491
// Return a node which is more "ideal" than the current node. Strip out
1493
Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {1494
Node* res = Ideal_common(phase, can_reshape);
1495
if (res != NodeSentinel) {1499
// Check for people making a useless boolean: things like
1500
// if( (x < y ? true : false) ) { ... }1501
// Replace with if( x < y ) { ... }1502
Node* bol2 = remove_useless_bool(this, phase);
1503
if (bol2) return bol2;
1505
if (in(0) == nullptr) return nullptr; // Dead loop?
1507
PhaseIterGVN* igvn = phase->is_IterGVN();
1508
Node* result = fold_compares(igvn);
1509
if (result != nullptr) {1513
// Scan for an equivalent test
1514
int dist = 4; // Cutoff limit for search
1515
if (is_If() && in(1)->is_Bool()) {1516
Node* cmp = in(1)->in(1);
1517
if (cmp->Opcode() == Op_CmpP &&
1518
cmp->in(2) != nullptr && // make sure cmp is not already dead
1519
cmp->in(2)->bottom_type() == TypePtr::NULL_PTR) {1520
dist = 64; // Limit for null-pointer scans
1524
Node* prev_dom = search_identical(dist, igvn);
1526
if (prev_dom != nullptr) {1527
// Replace dominated IfNode
1528
return dominated_by(prev_dom, igvn, false);
1531
return simple_subsuming(igvn);
1534
//------------------------------dominated_by-----------------------------------
1535
Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN* igvn, bool pin_array_access_nodes) {1537
if (TraceIterativeGVN) {1538
tty->print(" Removing IfNode: "); this->dump();1542
igvn->hash_delete(this); // Remove self to prevent spurious V-N
1544
// Need opcode to decide which way 'this' test goes
1545
int prev_op = prev_dom->Opcode();
1546
Node *top = igvn->C->top(); // Shortcut to top
1548
// Now walk the current IfNode's projections.
1549
// Loop ends when 'this' has no more uses.
1550
for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {1551
Node *ifp = last_out(i); // Get IfTrue/IfFalse
1552
igvn->add_users_to_worklist(ifp);
1553
// Check which projection it is and set target.
1554
// Data-target is either the dominating projection of the same type
1555
// or TOP if the dominating projection is of opposite type.
1556
// Data-target will be used as the new control edge for the non-CFG
1557
// nodes like Casts and Loads.
1558
Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1559
// Control-target is just the If's immediate dominator or TOP.
1560
Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top;
1562
// For each child of an IfTrue/IfFalse projection, reroute.
1563
// Loop ends when projection has no more uses.
1564
for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {1565
Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse
1566
if (s->depends_only_on_test() && igvn->no_dependent_zero_check(s)) {1567
// For control producers.
1568
// Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
1569
igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1570
if (pin_array_access_nodes && data_target != top) {1571
// As a result of range check smearing, Loads and range check Cast nodes that are control dependent on this
1572
// range check (that is about to be removed) now depend on multiple dominating range checks. After the removal
1573
// of this range check, these control dependent nodes end up at the lowest/nearest dominating check in the
1574
// graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
1575
// lowest dominating check is later replaced by yet another dominating check), we need to pin them at the
1576
// lowest dominating check.
1577
Node* clone = s->pin_array_access_node();
1578
if (clone != nullptr) {1579
clone = igvn->transform(clone);
1580
igvn->replace_node(s, clone);
1584
// Find the control input matching this def-use edge.
1585
// For Regions it may not be in slot 0.
1587
for (l = 0; s->in(l) != ifp; l++) { }1588
igvn->replace_input_of(s, l, ctrl_target);
1590
} // End for each child of a projection
1592
igvn->remove_dead_node(ifp);
1593
} // End for each IfTrue/IfFalse child of If
1596
igvn->remove_dead_node(this);
1598
// Must return either the original node (now dead) or a new node
1599
// (Do not return a top here, since that would break the uniqueness of top.)
1600
return new ConINode(TypeInt::ZERO);
1603
Node* IfNode::search_identical(int dist, PhaseIterGVN* igvn) {1604
// Setup to scan up the CFG looking for a dominating test
1606
Node* prev_dom = this;
1608
// Search up the dominator tree for an If with an identical test
1609
while (dom->Opcode() != op || // Not same opcode?
1610
!same_condition(dom, igvn) || // Not same input 1?
1611
prev_dom->in(0) != dom) { // One path of test does not dominate?1612
if (dist < 0) return nullptr;
1616
dom = up_one_dom(dom);
1617
if (!dom) return nullptr;
1620
// Check that we did not follow a loop back to ourselves
1626
if (dist > 2) { // Add to count of null checks elided1627
explicit_null_checks_elided++;
1634
bool IfNode::same_condition(const Node* dom, PhaseIterGVN* igvn) const {1635
Node* dom_bool = dom->in(1);
1636
Node* this_bool = in(1);
1637
if (dom_bool == this_bool) {1641
if (dom_bool == nullptr || !dom_bool->is_Bool() ||
1642
this_bool == nullptr || !this_bool->is_Bool()) {1645
Node* dom_cmp = dom_bool->in(1);
1646
Node* this_cmp = this_bool->in(1);
1648
// If the comparison is a subtype check, then SubTypeCheck nodes may have profile data attached to them and may be
1649
// different nodes even-though they perform the same subtype check
1650
if (dom_cmp == nullptr || !dom_cmp->is_SubTypeCheck() ||
1651
this_cmp == nullptr || !this_cmp->is_SubTypeCheck()) {1655
if (dom_cmp->in(1) != this_cmp->in(1) ||
1656
dom_cmp->in(2) != this_cmp->in(2) ||
1657
dom_bool->as_Bool()->_test._test != this_bool->as_Bool()->_test._test) {1665
static int subsuming_bool_test_encode(Node*);
1667
// Check if dominating test is subsuming 'this' one.
1679
// r2\ eqT eqF neT neF ltT ltF leT leF gtT gtF geT geF
1680
// eq t f f t f - - f f - - f
1681
// ne f t t f t - - t t - - t
1682
// lt f - - f t f - f f - f t
1683
// le t - - t t - t f f t - t
1684
// gt f - - f f - f t t f - f
1685
// ge t - - t f t - t t - t f
1687
Node* IfNode::simple_subsuming(PhaseIterGVN* igvn) {1688
// Table encoding: N/A (na), True-branch (tb), False-branch (fb).
1689
static enum { na, tb, fb } s_short_circuit_map[6][12] = {1690
/*rel: eq+T eq+F ne+T ne+F lt+T lt+F le+T le+F gt+T gt+F ge+T ge+F*/
1691
/*eq*/{ tb, fb, fb, tb, fb, na, na, fb, fb, na, na, fb },1692
/*ne*/{ fb, tb, tb, fb, tb, na, na, tb, tb, na, na, tb },1693
/*lt*/{ fb, na, na, fb, tb, fb, na, fb, fb, na, fb, tb },1694
/*le*/{ tb, na, na, tb, tb, na, tb, fb, fb, tb, na, tb },1695
/*gt*/{ fb, na, na, fb, fb, na, fb, tb, tb, fb, na, fb },1696
/*ge*/{ tb, na, na, tb, fb, tb, na, tb, tb, na, tb, fb }};1699
if (!pre->is_IfTrue() && !pre->is_IfFalse()) {1702
Node* dom = pre->in(0);
1703
if (!dom->is_If()) {1707
if (!bol->is_Bool()) {1710
Node* cmp = in(1)->in(1);
1711
if (!cmp->is_Cmp()) {1715
if (!dom->in(1)->is_Bool()) {1718
if (dom->in(1)->in(1) != cmp) { // Not same cond?1722
int drel = subsuming_bool_test_encode(dom->in(1));
1723
int trel = subsuming_bool_test_encode(bol);
1724
int bout = pre->is_IfFalse() ? 1 : 0;
1726
if (drel < 0 || trel < 0) {1729
int br = s_short_circuit_map[trel][2*drel+bout];
1734
if (TraceIterativeGVN) {1735
tty->print(" Subsumed IfNode: "); dump();1738
// Replace condition with constant True(1)/False(0).
1739
bool is_always_true = br == tb;
1740
set_req(1, igvn->intcon(is_always_true ? 1 : 0));
1742
// Update any data dependencies to the directly dominating test. This subsumed test is not immediately removed by igvn
1743
// and therefore subsequent optimizations might miss these data dependencies otherwise. There might be a dead loop
1744
// ('always_taken_proj' == 'pre') that is cleaned up later. Skip this case to make the iterator work properly.1745
Node* always_taken_proj = proj_out(is_always_true);
1746
if (always_taken_proj != pre) {1747
for (DUIterator_Fast imax, i = always_taken_proj->fast_outs(imax); i < imax; i++) {1748
Node* u = always_taken_proj->fast_out(i);
1750
igvn->replace_input_of(u, 0, pre);
1757
if (bol->outcnt() == 0) {1758
igvn->remove_dead_node(bol); // Kill the BoolNode.
1763
// Map BoolTest to local table encoding. The BoolTest (e)numerals
1764
// { eq = 0, ne = 4, le = 5, ge = 7, lt = 3, gt = 1 }1765
// are mapped to table indices, while the remaining (e)numerals in BoolTest
1766
// { overflow = 2, no_overflow = 6, never = 8, illegal = 9 }1767
// are ignored (these are not modeled in the table).
1769
static int subsuming_bool_test_encode(Node* node) {1770
precond(node->is_Bool());
1771
BoolTest::mask x = node->as_Bool()->_test._test;
1773
case BoolTest::eq: return 0;
1774
case BoolTest::ne: return 1;
1775
case BoolTest::lt: return 2;
1776
case BoolTest::le: return 3;
1777
case BoolTest::gt: return 4;
1778
case BoolTest::ge: return 5;
1779
case BoolTest::overflow:
1780
case BoolTest::no_overflow:
1781
case BoolTest::never:
1782
case BoolTest::illegal:
1788
//------------------------------Identity---------------------------------------
1789
// If the test is constant & we match, then we are the input Control
1790
Node* IfProjNode::Identity(PhaseGVN* phase) {1791
// Can only optimize if cannot go the other way
1792
const TypeTuple *t = phase->type(in(0))->is_tuple();
1793
if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
1794
// During parsing (GVN) we don't remove dead code aggressively.
1795
// Cut off dead branch and let PhaseRemoveUseless take care of it.
1796
(!phase->is_IterGVN() ||
1797
// During IGVN, first wait for the dead branch to be killed.
1798
// Otherwise, the IfNode's control will have two control uses (the IfNode
1799
// that doesn't go away because it still has uses and this branch of the
1800
// If) which breaks other optimizations. Node::has_special_unique_user()
1801
// will cause this node to be reprocessed once the dead branch is killed.
1802
in(0)->outcnt() == 1))) {1804
if (in(0)->is_BaseCountedLoopEnd()) {1805
// CountedLoopEndNode may be eliminated by if subsuming, replace CountedLoopNode with LoopNode to
1806
// avoid mismatching between CountedLoopNode and CountedLoopEndNode in the following optimization.
1807
Node* head = unique_ctrl_out_or_null();
1808
if (head != nullptr && head->is_BaseCountedLoop() && head->in(LoopNode::LoopBackControl) == this) {1809
Node* new_head = new LoopNode(head->in(LoopNode::EntryControl), this);
1810
phase->is_IterGVN()->register_new_node_with_optimizer(new_head);
1811
phase->is_IterGVN()->replace_node(head, new_head);
1814
return in(0)->in(0);
1820
bool IfNode::is_zero_trip_guard() const {1821
if (in(1)->is_Bool() && in(1)->in(1)->is_Cmp()) {1822
return in(1)->in(1)->in(1)->Opcode() == Op_OpaqueZeroTripGuard;
1827
void IfProjNode::pin_array_access_nodes(PhaseIterGVN* igvn) {1828
for (DUIterator i = outs(); has_out(i); i++) {1830
if (!u->depends_only_on_test()) {1833
Node* clone = u->pin_array_access_node();
1834
if (clone != nullptr) {1835
clone = igvn->transform(clone);
1836
assert(clone != u, "shouldn't common");
1837
igvn->replace_node(u, clone);
1844
void IfNode::dump_spec(outputStream* st) const {1845
switch (_assertion_predicate_type) {1846
case AssertionPredicateType::Init_value:
1847
st->print("#Init Value Assertion Predicate ");1849
case AssertionPredicateType::Last_value:
1850
st->print("#Last Value Assertion Predicate ");1852
case AssertionPredicateType::None:
1853
// No Assertion Predicate
1856
fatal("Unknown Assertion Predicate type");1858
st->print("P=%f, C=%f", _prob, _fcnt);1860
#endif // NOT PRODUCT
1862
//------------------------------idealize_test----------------------------------
1863
// Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and
1864
// come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms
1865
// converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as
1867
static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {1868
assert(iff->in(0) != nullptr, "If must be live");
1870
if (iff->outcnt() != 2) return nullptr; // Malformed projections.
1871
Node* old_if_f = iff->proj_out(false);
1872
Node* old_if_t = iff->proj_out(true);
1874
// CountedLoopEnds want the back-control test to be TRUE, regardless of
1875
// whether they are testing a 'gt' or 'lt' condition. The 'gt' condition
1876
// happens in count-down loops
1877
if (iff->is_BaseCountedLoopEnd()) return nullptr;
1878
if (!iff->in(1)->is_Bool()) return nullptr; // Happens for partially optimized IF tests
1879
BoolNode *b = iff->in(1)->as_Bool();
1880
BoolTest bt = b->_test;
1881
// Test already in good order?
1882
if( bt.is_canonical() )
1885
// Flip test to be canonical. Requires flipping the IfFalse/IfTrue and
1886
// cloning the IfNode.
1887
Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1888
if( !new_b->is_Bool() ) return nullptr;
1889
b = new_b->as_Bool();
1891
PhaseIterGVN *igvn = phase->is_IterGVN();
1892
assert( igvn, "Test is not canonical in parser?" );
1894
// The IF node never really changes, but it needs to be cloned
1895
iff = iff->clone()->as_If();
1897
iff->_prob = 1.0-iff->_prob;
1899
Node *prior = igvn->hash_find_insert(iff);
1901
igvn->remove_dead_node(iff);
1902
iff = (IfNode*)prior;
1904
// Cannot call transform on it just yet
1905
igvn->set_type_bottom(iff);
1907
igvn->_worklist.push(iff);
1909
// Now handle projections. Cloning not required.
1910
Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1911
Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1913
igvn->register_new_node_with_optimizer(new_if_f);
1914
igvn->register_new_node_with_optimizer(new_if_t);
1915
// Flip test, so flip trailing control
1916
igvn->replace_node(old_if_f, new_if_t);
1917
igvn->replace_node(old_if_t, new_if_f);
1923
Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) {1924
Node* res = Ideal_common(phase, can_reshape);
1925
if (res != NodeSentinel) {1929
PhaseIterGVN *igvn = phase->is_IterGVN();
1930
// Setup to scan up the CFG looking for a dominating test
1931
Node* prev_dom = this;
1933
// Check for range-check vs other kinds of tests
1937
int flip1 = is_range_check(range1, index1, offset1);
1940
// Try to remove extra range checks. All 'up_one_dom' gives up at merges
1941
// so all checks we inspect post-dominate the top-most check we find.
1942
// If we are going to fail the current check and we reach the top check
1943
// then we are guaranteed to fail, so just start interpreting there.
1944
// We 'expand' the top 3 range checks to include all post-dominating
1948
// a[i+x] // (1) 1 < x < 6
1951
// a[i+6] // max = max of all constants
1953
// a[i+1] // min = min of all constants
1956
// (1) a[i+x]: Leave unchanged
1957
// (2) a[i+3]: Replace with a[i+max] = a[i+6]: i+x < i+3 <= i+6 -> (2) is covered
1958
// (3) a[i+4]: Replace with a[i+min] = a[i+1]: i+1 < i+4 <= i+6 -> (3) and all following checks are covered
1959
// Remove all other a[i+c] checks
1962
// (1) a[i+x]: Leave unchanged
1963
// (2) a[i+3]: Replace with a[i+min] = a[i+1]: i+1 < i+3 <= i+x -> (2) is covered
1964
// (3) a[i+4]: Replace with a[i+max] = a[i+6]: i+1 < i+4 <= i+6 -> (3) and all following checks are covered
1965
// Remove all other a[i+c] checks
1967
// We only need the top 2 range checks if x is the min or max of all constants.
1969
// This, however, only works if the interval [i+min,i+max] is not larger than max_int (i.e. abs(max - min) < max_int):
1970
// The theoretical max size of an array is max_int with:
1971
// - Valid index space: [0,max_int-1]
1972
// - Invalid index space: [max_int,-1] // max_int, min_int, min_int - 1 ..., -1
1974
// The size of the consecutive valid index space is smaller than the size of the consecutive invalid index space.
1975
// If we choose min and max in such a way that:
1976
// - abs(max - min) < max_int
1977
// - i+max and i+min are inside the valid index space
1978
// then all indices [i+min,i+max] must be in the valid index space. Otherwise, the invalid index space must be
1979
// smaller than the valid index space which is never the case for any array size.
1981
// Choosing a smaller array size only makes the valid index space smaller and the invalid index space larger and
1982
// the argument above still holds.
1984
// Note that the same optimization with the same maximal accepted interval size can also be found in C1.
1985
const jlong maximum_number_of_min_max_interval_indices = (jlong)max_jint;
1987
// The top 3 range checks seen
1989
RangeCheck prev_checks[NRC];
1992
// Low and high offsets seen so far
1993
jint off_lo = offset1;
1994
jint off_hi = offset1;
1996
bool found_immediate_dominator = false;
1998
// Scan for the top checks and collect range of offsets
1999
for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit2000
if (dom->Opcode() == Op_RangeCheck && // Not same opcode?
2001
prev_dom->in(0) == dom) { // One path of test does dominate?2002
if (dom == this) return nullptr; // dead loop
2003
// See if this is a range check
2007
int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2);
2008
// See if this is a _matching_ range check, checking against
2009
// the same array bounds.
2010
if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
2011
dom->outcnt() == 2) {2012
if (nb_checks == 0 && dom->in(1) == in(1)) {2013
// Found an immediately dominating test at the same offset.
2014
// This kind of back-to-back test can be eliminated locally,
2015
// and there is no need to search further for dominating tests.
2016
assert(offset2 == offset1, "Same test but different offsets");
2017
found_immediate_dominator = true;
2021
// "x - y" -> must add one to the difference for number of elements in [x,y]
2022
const jlong diff = (jlong)MIN2(offset2, off_lo) - (jlong)MAX2(offset2, off_hi);
2023
if (ABS(diff) < maximum_number_of_min_max_interval_indices) {2024
// Gather expanded bounds
2025
off_lo = MIN2(off_lo, offset2);
2026
off_hi = MAX2(off_hi, offset2);
2027
// Record top NRC range checks
2028
prev_checks[nb_checks % NRC].ctl = prev_dom->as_IfProj();
2029
prev_checks[nb_checks % NRC].off = offset2;
2035
dom = up_one_dom(dom);
2039
if (!found_immediate_dominator) {2040
// Attempt to widen the dominating range check to cover some later
2041
// ones. Since range checks "fail" by uncommon-trapping to the
2042
// interpreter, widening a check can make us speculatively enter
2043
// the interpreter. If we see range-check deopt's, do not widen!
2044
if (!phase->C->allow_range_check_smearing()) return nullptr;
2046
if (can_reshape && !phase->C->post_loop_opts_phase()) {2047
// We are about to perform range check smearing (i.e. remove this RangeCheck if it is dominated by
2048
// a series of RangeChecks which have a range that covers this RangeCheck). This can cause array access nodes to
2049
// be pinned. We want to avoid that and first allow range check elimination a chance to remove the RangeChecks
2050
// from loops. Hence, we delay range check smearing until after loop opts.
2051
phase->C->record_for_post_loop_opts_igvn(this);
2055
// Didn't find prior covering check, so cannot remove anything.
2056
if (nb_checks == 0) {2059
// Constant indices only need to check the upper bound.
2060
// Non-constant indices must check both low and high.
2061
int chk0 = (nb_checks - 1) % NRC;
2063
if (nb_checks == 1) {2066
// If the top range check's constant is the min or max of
2067
// all constants we widen the next one to cover the whole
2068
// range of constants.
2069
RangeCheck rc0 = prev_checks[chk0];
2070
int chk1 = (nb_checks - 2) % NRC;
2071
RangeCheck rc1 = prev_checks[chk1];
2072
if (rc0.off == off_lo) {2073
adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
2075
} else if (rc0.off == off_hi) {2076
adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
2079
// If the top test's constant is not the min or max of all
2080
// constants, we need 3 range checks. We must leave the
2081
// top test unchanged because widening it would allow the
2082
// accesses it protects to successfully read/write out of
2084
if (nb_checks == 2) {2087
int chk2 = (nb_checks - 3) % NRC;
2088
RangeCheck rc2 = prev_checks[chk2];
2089
// The top range check a+i covers interval: -a <= i < length-a
2090
// The second range check b+i covers interval: -b <= i < length-b
2091
if (rc1.off <= rc0.off) {2092
// if b <= a, we change the second range check to:
2093
// -min_of_all_constants <= i < length-min_of_all_constants
2094
// Together top and second range checks now cover:
2095
// -min_of_all_constants <= i < length-a
2096
// which is more restrictive than -b <= i < length-b:
2097
// -b <= -min_of_all_constants <= i < length-a <= length-b
2098
// The third check is then changed to:
2099
// -max_of_all_constants <= i < length-max_of_all_constants
2100
// so 2nd and 3rd checks restrict allowed values of i to:
2101
// -min_of_all_constants <= i < length-max_of_all_constants
2102
adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
2103
adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
2105
// if b > a, we change the second range check to:
2106
// -max_of_all_constants <= i < length-max_of_all_constants
2107
// Together top and second range checks now cover:
2108
// -a <= i < length-max_of_all_constants
2109
// which is more restrictive than -b <= i < length-b:
2110
// -b < -a <= i < length-max_of_all_constants <= length-b
2111
// The third check is then changed to:
2112
// -max_of_all_constants <= i < length-max_of_all_constants
2113
// so 2nd and 3rd checks restrict allowed values of i to:
2114
// -min_of_all_constants <= i < length-max_of_all_constants
2115
adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
2116
adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
2122
RangeCheck rc0 = prev_checks[chk0];
2123
// 'Widen' the offset of the 1st and only covering check
2124
adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
2125
// Test is now covered by prior checks, dominate it out
2128
// The last RangeCheck is found to be redundant with a sequence of n (n >= 2) preceding RangeChecks.
2129
// If an array load is control dependent on the eliminated range check, the array load nodes (CastII and Load)
2130
// become control dependent on the last range check of the sequence, but they are really dependent on the entire
2131
// sequence of RangeChecks. If RangeCheck#n is later replaced by a dominating identical check, the array load
2132
// nodes must not float above the n-1 other RangeCheck in the sequence. We pin the array load nodes here to
2133
// guarantee it doesn't happen.
2135
// RangeCheck#1 RangeCheck#1
2137
// | uncommon trap | uncommon trap
2139
// RangeCheck#n -> RangeCheck#n
2141
// | uncommon trap CastII uncommon trap
2144
// CastII uncommon trap
2147
return dominated_by(prev_dom, igvn, true);
2150
prev_dom = search_identical(4, igvn);
2152
if (prev_dom == nullptr) {2157
// Replace dominated IfNode
2158
return dominated_by(prev_dom, igvn, false);
2161
ParsePredicateNode::ParsePredicateNode(Node* control, Deoptimization::DeoptReason deopt_reason, PhaseGVN* gvn)
2162
: IfNode(control, gvn->intcon(1), PROB_MAX, COUNT_UNKNOWN),
2163
_deopt_reason(deopt_reason),
2165
init_class_id(Class_ParsePredicate);
2166
gvn->C->add_parse_predicate(this);
2167
gvn->C->record_for_post_loop_opts_igvn(this);
2169
switch (deopt_reason) {2170
case Deoptimization::Reason_predicate:
2171
case Deoptimization::Reason_profile_predicate:
2172
case Deoptimization::Reason_loop_limit_check:
2175
assert(false, "unsupported deoptimization reason for Parse Predicate");
2180
Node* ParsePredicateNode::uncommon_trap() const {2181
ParsePredicateUncommonProj* uncommon_proj = proj_out(0)->as_IfFalse();
2182
Node* uct_region_or_call = uncommon_proj->unique_ctrl_out();
2183
assert(uct_region_or_call->is_Region() || uct_region_or_call->is_Call(), "must be a region or call uct");
2184
return uct_region_or_call;
2187
// Fold this node away once it becomes useless or at latest in post loop opts IGVN.
2188
const Type* ParsePredicateNode::Value(PhaseGVN* phase) const {2189
if (phase->type(in(0)) == Type::TOP) {2192
if (_useless || phase->C->post_loop_opts_phase()) {2193
return TypeTuple::IFTRUE;
2195
return bottom_type();
2200
void ParsePredicateNode::dump_spec(outputStream* st) const {2202
switch (_deopt_reason) {2203
case Deoptimization::DeoptReason::Reason_predicate:
2206
case Deoptimization::DeoptReason::Reason_profile_predicate:
2207
st->print("Profiled_Loop ");2209
case Deoptimization::DeoptReason::Reason_loop_limit_check:
2210
st->print("Loop_Limit_Check ");2213
fatal("unknown kind");2216
st->print("#useless ");2219
#endif // NOT PRODUCT