1 /*
  2  * Copyright (c) 2014, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "opto/addnode.hpp"
 27 #include "opto/callnode.hpp"
 28 #include "opto/castnode.hpp"
 29 #include "opto/connode.hpp"
 30 #include "opto/graphKit.hpp"
 31 #include "opto/inlinetypenode.hpp"
 32 #include "opto/matcher.hpp"
 33 #include "opto/phaseX.hpp"
 34 #include "opto/rootnode.hpp"
 35 #include "opto/subnode.hpp"
 36 #include "opto/type.hpp"
 37 #include "castnode.hpp"
 38 
 39 //=============================================================================
 40 // If input is already higher or equal to cast type, then this is an identity.
 41 Node* ConstraintCastNode::Identity(PhaseGVN* phase) {
 42   Node* dom = dominating_cast(phase, phase);
 43   if (dom != nullptr) {
 44     return dom;
 45   }
 46   if (_dependency != RegularDependency) {
 47     return this;
 48   }
 49   return phase->type(in(1))->higher_equal_speculative(_type) ? in(1) : this;
 50 }
 51 
 52 //------------------------------Value------------------------------------------
 53 // Take 'join' of input and cast-up type
 54 const Type* ConstraintCastNode::Value(PhaseGVN* phase) const {
 55   if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
 56 
 57   const Type* in_type = phase->type(in(1));
 58   const Type* ft = in_type->filter_speculative(_type);
 59 
 60   // Check if both _type and in_type had a speculative type, but for the just
 61   // computed ft the speculative type was dropped.
 62   if (ft->speculative() == nullptr &&
 63       _type->speculative() != nullptr &&
 64       in_type->speculative() != nullptr) {
 65     // Speculative type may have disagreed between cast and input, and was
 66     // dropped in filtering. Recompute so that ft can take speculative type
 67     // of in_type. If we did not do it now, a subsequent ::Value call would
 68     // do it, and violate idempotence of ::Value.
 69     ft = in_type->filter_speculative(ft);
 70   }
 71 
 72 #ifdef ASSERT
 73   // Previous versions of this function had some special case logic,
 74   // which is no longer necessary.  Make sure of the required effects.
 75   switch (Opcode()) {
 76     case Op_CastII:
 77     {
 78       if (in_type == Type::TOP) {
 79         assert(ft == Type::TOP, "special case #1");
 80       }
 81       const Type* rt = in_type->join_speculative(_type);
 82       if (rt->empty()) {
 83         assert(ft == Type::TOP, "special case #2");
 84       }
 85       break;
 86     }
 87     case Op_CastPP:
 88     if (in_type == TypePtr::NULL_PTR &&
 89         _type->isa_ptr() && _type->is_ptr()->_ptr == TypePtr::NotNull) {
 90       assert(ft == Type::TOP, "special case #3");
 91       break;
 92     }
 93   }
 94 #endif //ASSERT
 95 
 96   return ft;
 97 }
 98 
 99 //------------------------------Ideal------------------------------------------
100 // Return a node which is more "ideal" than the current node.  Strip out
101 // control copies
102 Node *ConstraintCastNode::Ideal(PhaseGVN *phase, bool can_reshape) {
103   if (in(0) && remove_dead_region(phase, can_reshape)) {
104     return this;
105   }
106 
107   // Push cast through InlineTypeNode
108   InlineTypeNode* vt = in(1)->isa_InlineType();
109   if (vt != nullptr && phase->type(vt)->filter_speculative(_type) != Type::TOP) {
110     Node* cast = clone();
111     cast->set_req(1, vt->get_oop());
112     vt = vt->clone()->as_InlineType();
113     vt->set_oop(phase->transform(cast));
114     return vt;
115   }
116 
117   return nullptr;
118 }
119 
120 bool ConstraintCastNode::cmp(const Node &n) const {
121   return TypeNode::cmp(n) && ((ConstraintCastNode&)n)._dependency == _dependency;
122 }
123 
124 uint ConstraintCastNode::size_of() const {
125   return sizeof(*this);
126 }
127 
128 Node* ConstraintCastNode::make_cast(int opcode, Node* c, Node *n, const Type *t, DependencyType dependency) {
129   switch(opcode) {
130   case Op_CastII: {
131     Node* cast = new CastIINode(n, t, dependency);
132     cast->set_req(0, c);
133     return cast;
134   }
135   case Op_CastLL: {
136     Node* cast = new CastLLNode(n, t, dependency);
137     cast->set_req(0, c);
138     return cast;
139   }
140   case Op_CastPP: {
141     Node* cast = new CastPPNode(n, t, dependency);
142     cast->set_req(0, c);
143     return cast;
144   }
145   case Op_CastFF: {
146     Node* cast = new CastFFNode(n, t, dependency);
147     cast->set_req(0, c);
148     return cast;
149   }
150   case Op_CastDD: {
151     Node* cast = new CastDDNode(n, t, dependency);
152     cast->set_req(0, c);
153     return cast;
154   }
155   case Op_CastVV: {
156     Node* cast = new CastVVNode(n, t, dependency);
157     cast->set_req(0, c);
158     return cast;
159   }
160   case Op_CheckCastPP: return new CheckCastPPNode(c, n, t, dependency);
161   default:
162     fatal("Bad opcode %d", opcode);
163   }
164   return nullptr;
165 }
166 
167 Node* ConstraintCastNode::make(Node* c, Node *n, const Type *t, DependencyType dependency, BasicType bt) {
168   switch(bt) {
169   case T_INT: {
170     return make_cast(Op_CastII, c, n, t, dependency);
171   }
172   case T_LONG: {
173     return make_cast(Op_CastLL, c, n, t, dependency);
174   }
175   default:
176     fatal("Bad basic type %s", type2name(bt));
177   }
178   return nullptr;
179 }
180 
181 TypeNode* ConstraintCastNode::dominating_cast(PhaseGVN* gvn, PhaseTransform* pt) const {
182   if (_dependency == UnconditionalDependency) {
183     return nullptr;
184   }
185   Node* val = in(1);
186   Node* ctl = in(0);
187   int opc = Opcode();
188   if (ctl == nullptr) {
189     return nullptr;
190   }
191   // Range check CastIIs may all end up under a single range check and
192   // in that case only the narrower CastII would be kept by the code
193   // below which would be incorrect.
194   if (is_CastII() && as_CastII()->has_range_check()) {
195     return nullptr;
196   }
197   if (type()->isa_rawptr() && (gvn->type_or_null(val) == nullptr || gvn->type(val)->isa_oopptr())) {
198     return nullptr;
199   }
200   for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
201     Node* u = val->fast_out(i);
202     if (u != this &&
203         u->outcnt() > 0 &&
204         u->Opcode() == opc &&
205         u->in(0) != nullptr &&
206         u->bottom_type()->higher_equal(type())) {
207       if (pt->is_dominator(u->in(0), ctl)) {
208         return u->as_Type();
209       }
210       if (is_CheckCastPP() && u->in(1)->is_Proj() && u->in(1)->in(0)->is_Allocate() &&
211           u->in(0)->is_Proj() && u->in(0)->in(0)->is_Initialize() &&
212           u->in(1)->in(0)->as_Allocate()->initialization() == u->in(0)->in(0)) {
213         // CheckCastPP following an allocation always dominates all
214         // use of the allocation result
215         return u->as_Type();
216       }
217     }
218   }
219   return nullptr;
220 }
221 
222 #ifndef PRODUCT
223 void ConstraintCastNode::dump_spec(outputStream *st) const {
224   TypeNode::dump_spec(st);
225   if (_dependency != RegularDependency) {
226     st->print(" %s dependency", _dependency == StrongDependency ? "strong" : "unconditional");
227   }
228 }
229 #endif
230 
231 const Type* CastIINode::Value(PhaseGVN* phase) const {
232   const Type *res = ConstraintCastNode::Value(phase);
233   if (res == Type::TOP) {
234     return Type::TOP;
235   }
236   assert(res->isa_int(), "res must be int");
237 
238   // Similar to ConvI2LNode::Value() for the same reasons
239   // see if we can remove type assertion after loop opts
240   // But here we have to pay extra attention:
241   // Do not narrow the type of range check dependent CastIINodes to
242   // avoid corruption of the graph if a CastII is replaced by TOP but
243   // the corresponding range check is not removed.
244   if (!_range_check_dependency) {
245     res = widen_type(phase, res, T_INT);
246   }
247 
248   // Try to improve the type of the CastII if we recognize a CmpI/If pattern.
249   //
250   // in1  in2
251   //  |    |
252   //  +--- | --+
253   //  |    |   |
254   // CmpINode  |
255   //    |      |
256   // BoolNode  |
257   //    |      |
258   //  IfNode   |
259   //    |      |
260   //  IfProj   |
261   //    |      |
262   //   CastIINode
263   //
264   if (carry_dependency()) {
265     if (in(0) != nullptr && in(0)->in(0) != nullptr && in(0)->in(0)->is_If()) {
266       assert(in(0)->is_IfFalse() || in(0)->is_IfTrue(), "should be If proj");
267       Node* proj = in(0);
268       if (proj->in(0)->in(1)->is_Bool()) {
269         Node* b = proj->in(0)->in(1);
270         if (b->in(1)->Opcode() == Op_CmpI) {
271           Node* cmp = b->in(1);
272           if (cmp->in(1) == in(1) && phase->type(cmp->in(2))->isa_int()) {
273             const TypeInt* in2_t = phase->type(cmp->in(2))->is_int();
274             const Type* t = TypeInt::INT;
275             BoolTest test = b->as_Bool()->_test;
276             if (proj->is_IfFalse()) {
277               test = test.negate();
278             }
279             BoolTest::mask m = test._test;
280             jlong lo_long = min_jint;
281             jlong hi_long = max_jint;
282             if (m == BoolTest::le || m == BoolTest::lt) {
283               hi_long = in2_t->_hi;
284               if (m == BoolTest::lt) {
285                 hi_long -= 1;
286               }
287             } else if (m == BoolTest::ge || m == BoolTest::gt) {
288               lo_long = in2_t->_lo;
289               if (m == BoolTest::gt) {
290                 lo_long += 1;
291               }
292             } else if (m == BoolTest::eq) {
293               lo_long = in2_t->_lo;
294               hi_long = in2_t->_hi;
295             } else if (m == BoolTest::ne) {
296               // can't do any better
297             } else {
298               stringStream ss;
299               test.dump_on(&ss);
300               fatal("unexpected comparison %s", ss.freeze());
301             }
302             int lo_int = (int)lo_long;
303             int hi_int = (int)hi_long;
304 
305             if (lo_long != (jlong)lo_int) {
306               lo_int = min_jint;
307             }
308             if (hi_long != (jlong)hi_int) {
309               hi_int = max_jint;
310             }
311 
312             t = TypeInt::make(lo_int, hi_int, Type::WidenMax);
313 
314             res = res->filter_speculative(t);
315             return res;
316           }
317         }
318       }
319     }
320   }
321   return res;
322 }
323 
324 static Node* find_or_make_integer_cast(PhaseIterGVN* igvn, Node* parent, Node* control, const TypeInteger* type, ConstraintCastNode::DependencyType dependency, BasicType bt) {
325   Node* n = ConstraintCastNode::make(control, parent, type, dependency, bt);
326   Node* existing = igvn->hash_find_insert(n);
327   if (existing != nullptr) {
328     n->destruct(igvn);
329     return existing;
330   }
331   return igvn->register_new_node_with_optimizer(n);
332 }
333 
334 Node *CastIINode::Ideal(PhaseGVN *phase, bool can_reshape) {
335   Node* progress = ConstraintCastNode::Ideal(phase, can_reshape);
336   if (progress != nullptr) {
337     return progress;
338   }
339   if (can_reshape && !_range_check_dependency && !phase->C->post_loop_opts_phase()) {
340     // makes sure we run ::Value to potentially remove type assertion after loop opts
341     phase->C->record_for_post_loop_opts_igvn(this);
342   }
343   if (!_range_check_dependency) {
344     return optimize_integer_cast(phase, T_INT);
345   }
346   return nullptr;
347 }
348 
349 Node* CastIINode::Identity(PhaseGVN* phase) {
350   Node* progress = ConstraintCastNode::Identity(phase);
351   if (progress != this) {
352     return progress;
353   }
354   if (_range_check_dependency) {
355     if (phase->C->post_loop_opts_phase()) {
356       return this->in(1);
357     } else {
358       phase->C->record_for_post_loop_opts_igvn(this);
359     }
360   }
361   return this;
362 }
363 
364 bool CastIINode::cmp(const Node &n) const {
365   return ConstraintCastNode::cmp(n) && ((CastIINode&)n)._range_check_dependency == _range_check_dependency;
366 }
367 
368 uint CastIINode::size_of() const {
369   return sizeof(*this);
370 }
371 
372 #ifndef PRODUCT
373 void CastIINode::dump_spec(outputStream* st) const {
374   ConstraintCastNode::dump_spec(st);
375   if (_range_check_dependency) {
376     st->print(" range check dependency");
377   }
378 }
379 #endif
380 
381 const Type* CastLLNode::Value(PhaseGVN* phase) const {
382   const Type* res = ConstraintCastNode::Value(phase);
383   if (res == Type::TOP) {
384     return Type::TOP;
385   }
386   assert(res->isa_long(), "res must be long");
387 
388   return widen_type(phase, res, T_LONG);
389 }
390 
391 Node* CastLLNode::Ideal(PhaseGVN* phase, bool can_reshape) {
392   Node* progress = ConstraintCastNode::Ideal(phase, can_reshape);
393   if (progress != nullptr) {
394     return progress;
395   }
396   if (!phase->C->post_loop_opts_phase()) {
397     // makes sure we run ::Value to potentially remove type assertion after loop opts
398     phase->C->record_for_post_loop_opts_igvn(this);
399   }
400   // transform (CastLL (ConvI2L ..)) into (ConvI2L (CastII ..)) if the type of the CastLL is narrower than the type of
401   // the ConvI2L.
402   Node* in1 = in(1);
403   if (in1 != nullptr && in1->Opcode() == Op_ConvI2L) {
404     const Type* t = Value(phase);
405     const Type* t_in = phase->type(in1);
406     if (t != Type::TOP && t_in != Type::TOP) {
407       const TypeLong* tl = t->is_long();
408       const TypeLong* t_in_l = t_in->is_long();
409       assert(tl->_lo >= t_in_l->_lo && tl->_hi <= t_in_l->_hi, "CastLL type should be narrower than or equal to the type of its input");
410       assert((tl != t_in_l) == (tl->_lo > t_in_l->_lo || tl->_hi < t_in_l->_hi), "if type differs then this nodes's type must be narrower");
411       if (tl != t_in_l) {
412         const TypeInt* ti = TypeInt::make(checked_cast<jint>(tl->_lo), checked_cast<jint>(tl->_hi), tl->_widen);
413         Node* castii = phase->transform(new CastIINode(in(0), in1->in(1), ti));
414         Node* convi2l = in1->clone();
415         convi2l->set_req(1, castii);
416         return convi2l;
417       }
418     }
419   }
420   return optimize_integer_cast(phase, T_LONG);
421 }
422 
423 //=============================================================================
424 //------------------------------Identity---------------------------------------
425 // If input is already higher or equal to cast type, then this is an identity.
426 Node* CheckCastPPNode::Identity(PhaseGVN* phase) {
427   if (in(1)->is_InlineType() && _type->isa_instptr() && phase->type(in(1))->inline_klass()->is_subtype_of(_type->is_instptr()->instance_klass())) {
428     return in(1);
429   }
430   return ConstraintCastNode::Identity(phase);
431 }
432 
433 //------------------------------Value------------------------------------------
434 // Take 'join' of input and cast-up type, unless working with an Interface
435 const Type* CheckCastPPNode::Value(PhaseGVN* phase) const {
436   if( in(0) && phase->type(in(0)) == Type::TOP ) return Type::TOP;
437 
438   const Type *inn = phase->type(in(1));
439   if( inn == Type::TOP ) return Type::TOP;  // No information yet
440 
441   if (inn->isa_oopptr() && _type->isa_oopptr()) {
442     return ConstraintCastNode::Value(phase);
443   }
444 
445   const TypePtr *in_type = inn->isa_ptr();
446   const TypePtr *my_type = _type->isa_ptr();
447   const Type *result = _type;
448   if (in_type != nullptr && my_type != nullptr) {
449     // TODO 8302672
450     if (!StressReflectiveCode && my_type->isa_aryptr() && in_type->isa_aryptr()) {
451       // Propagate array properties (not flat/null-free)
452       // Don't do this when StressReflectiveCode is enabled because it might lead to
453       // a dying data path while the corresponding flat/null-free check is not folded.
454       my_type = my_type->is_aryptr()->update_properties(in_type->is_aryptr());
455       if (my_type == nullptr) {
456         return Type::TOP; // Inconsistent properties
457       }
458     }
459     TypePtr::PTR in_ptr = in_type->ptr();
460     if (in_ptr == TypePtr::Null) {
461       result = in_type;
462     } else if (in_ptr != TypePtr::Constant) {
463       result = my_type->cast_to_ptr_type(my_type->join_ptr(in_ptr));
464     }
465   }
466 
467   return result;
468 }
469 
470 //=============================================================================
471 //------------------------------Value------------------------------------------
472 const Type* CastX2PNode::Value(PhaseGVN* phase) const {
473   const Type* t = phase->type(in(1));
474   if (t == Type::TOP) return Type::TOP;
475   if (t->base() == Type_X && t->singleton()) {
476     uintptr_t bits = (uintptr_t) t->is_intptr_t()->get_con();
477     if (bits == 0)   return TypePtr::NULL_PTR;
478     return TypeRawPtr::make((address) bits);
479   }
480   return CastX2PNode::bottom_type();
481 }
482 
483 //------------------------------Idealize---------------------------------------
484 static inline bool fits_in_int(const Type* t, bool but_not_min_int = false) {
485   if (t == Type::TOP)  return false;
486   const TypeX* tl = t->is_intptr_t();
487   jint lo = min_jint;
488   jint hi = max_jint;
489   if (but_not_min_int)  ++lo;  // caller wants to negate the value w/o overflow
490   return (tl->_lo >= lo) && (tl->_hi <= hi);
491 }
492 
493 static inline Node* addP_of_X2P(PhaseGVN *phase,
494                                 Node* base,
495                                 Node* dispX,
496                                 bool negate = false) {
497   if (negate) {
498     dispX = phase->transform(new SubXNode(phase->MakeConX(0), dispX));
499   }
500   return new AddPNode(phase->C->top(),
501                       phase->transform(new CastX2PNode(base)),
502                       dispX);
503 }
504 
505 Node *CastX2PNode::Ideal(PhaseGVN *phase, bool can_reshape) {
506   // convert CastX2P(AddX(x, y)) to AddP(CastX2P(x), y) if y fits in an int
507   int op = in(1)->Opcode();
508   Node* x;
509   Node* y;
510   switch (op) {
511     case Op_SubX:
512     x = in(1)->in(1);
513     // Avoid ideal transformations ping-pong between this and AddP for raw pointers.
514     if (phase->find_intptr_t_con(x, -1) == 0)
515     break;
516     y = in(1)->in(2);
517     if (fits_in_int(phase->type(y), true)) {
518       return addP_of_X2P(phase, x, y, true);
519     }
520     break;
521     case Op_AddX:
522     x = in(1)->in(1);
523     y = in(1)->in(2);
524     if (fits_in_int(phase->type(y))) {
525       return addP_of_X2P(phase, x, y);
526     }
527     if (fits_in_int(phase->type(x))) {
528       return addP_of_X2P(phase, y, x);
529     }
530     break;
531   }
532   return nullptr;
533 }
534 
535 //------------------------------Identity---------------------------------------
536 Node* CastX2PNode::Identity(PhaseGVN* phase) {
537   if (in(1)->Opcode() == Op_CastP2X)  return in(1)->in(1);
538   return this;
539 }
540 
541 //=============================================================================
542 //------------------------------Value------------------------------------------
543 const Type* CastP2XNode::Value(PhaseGVN* phase) const {
544   const Type* t = phase->type(in(1));
545   if (t == Type::TOP) return Type::TOP;
546   if (t->base() == Type::RawPtr && t->singleton()) {
547     uintptr_t bits = (uintptr_t) t->is_rawptr()->get_con();
548     return TypeX::make(bits);
549   }
550 
551   if (t->is_zero_type() || !t->maybe_null()) {
552     for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
553       Node* u = fast_out(i);
554       if (u->Opcode() == Op_OrL) {
555         for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
556           Node* cmp = u->fast_out(j);
557           if (cmp->Opcode() == Op_CmpL) {
558             // Give CmpL a chance to get optimized
559             phase->record_for_igvn(cmp);
560           }
561         }
562       }
563     }
564   }
565 
566   return CastP2XNode::bottom_type();
567 }
568 
569 Node *CastP2XNode::Ideal(PhaseGVN *phase, bool can_reshape) {
570   return (in(0) && remove_dead_region(phase, can_reshape)) ? this : nullptr;
571 }
572 
573 //------------------------------Identity---------------------------------------
574 Node* CastP2XNode::Identity(PhaseGVN* phase) {
575   if (in(1)->Opcode() == Op_CastX2P)  return in(1)->in(1);
576   return this;
577 }
578 
579 Node* ConstraintCastNode::make_cast_for_type(Node* c, Node* in, const Type* type, DependencyType dependency) {
580   Node* cast= nullptr;
581   if (type->isa_int()) {
582     cast = make_cast(Op_CastII, c, in, type, dependency);
583   } else if (type->isa_long()) {
584     cast = make_cast(Op_CastLL, c, in, type, dependency);
585   } else if (type->isa_float()) {
586     cast = make_cast(Op_CastFF, c, in, type, dependency);
587   } else if (type->isa_double()) {
588     cast = make_cast(Op_CastDD, c, in, type, dependency);
589   } else if (type->isa_vect()) {
590     cast = make_cast(Op_CastVV, c, in, type, dependency);
591   } else if (type->isa_ptr()) {
592     cast = make_cast(Op_CastPP, c, in, type, dependency);
593   }
594   return cast;
595 }
596 
597 Node* ConstraintCastNode::optimize_integer_cast(PhaseGVN* phase, BasicType bt) {
598   PhaseIterGVN *igvn = phase->is_IterGVN();
599   const TypeInteger* this_type = this->type()->is_integer(bt);
600   Node* z = in(1);
601   const TypeInteger* rx = nullptr;
602   const TypeInteger* ry = nullptr;
603   // Similar to ConvI2LNode::Ideal() for the same reasons
604   if (Compile::push_thru_add(phase, z, this_type, rx, ry, bt, bt)) {
605     if (igvn == nullptr) {
606       // Postpone this optimization to iterative GVN, where we can handle deep
607       // AddI chains without an exponential number of recursive Ideal() calls.
608       phase->record_for_igvn(this);
609       return nullptr;
610     }
611     int op = z->Opcode();
612     Node* x = z->in(1);
613     Node* y = z->in(2);
614 
615     Node* cx = find_or_make_integer_cast(igvn, x, in(0), rx, _dependency, bt);
616     Node* cy = find_or_make_integer_cast(igvn, y, in(0), ry, _dependency, bt);
617     if (op == Op_Add(bt)) {
618       return AddNode::make(cx, cy, bt);
619     } else {
620       assert(op == Op_Sub(bt), "");
621       return SubNode::make(cx, cy, bt);
622     }
623     return nullptr;
624   }
625   return nullptr;
626 }
627 
628 const Type* ConstraintCastNode::widen_type(const PhaseGVN* phase, const Type* res, BasicType bt) const {
629   if (!phase->C->post_loop_opts_phase()) {
630     return res;
631   }
632   const TypeInteger* this_type = res->is_integer(bt);
633   const TypeInteger* in_type = phase->type(in(1))->isa_integer(bt);
634   if (in_type != nullptr &&
635       (in_type->lo_as_long() != this_type->lo_as_long() ||
636        in_type->hi_as_long() != this_type->hi_as_long())) {
637     jlong lo1 = this_type->lo_as_long();
638     jlong hi1 = this_type->hi_as_long();
639     int w1 = this_type->_widen;
640     if (lo1 >= 0) {
641       // Keep a range assertion of >=0.
642       lo1 = 0;        hi1 = max_signed_integer(bt);
643     } else if (hi1 < 0) {
644       // Keep a range assertion of <0.
645       lo1 = min_signed_integer(bt); hi1 = -1;
646     } else {
647       lo1 = min_signed_integer(bt); hi1 = max_signed_integer(bt);
648     }
649     return TypeInteger::make(MAX2(in_type->lo_as_long(), lo1),
650                              MIN2(in_type->hi_as_long(), hi1),
651                              MAX2((int)in_type->_widen, w1), bt);
652   }
653   return res;
654 }