1 /*
  2  * Copyright (c) 2020, 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/connode.hpp"
 29 #include "opto/convertnode.hpp"
 30 #include "opto/phaseX.hpp"
 31 #include "opto/rootnode.hpp"
 32 #include "opto/subnode.hpp"
 33 #include "opto/subtypenode.hpp"
 34 
 35 const Type* SubTypeCheckNode::sub(const Type* sub_t, const Type* super_t) const {
 36   const TypeKlassPtr* superk = super_t->isa_klassptr();
 37   const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
 38 
 39   // Oop can't be a subtype of abstract type that has no subclass.
 40   if (sub_t->isa_oopptr() && superk->isa_instklassptr() && superk->klass_is_exact()) {
 41     ciKlass* superklass = superk->exact_klass();
 42     if (!superklass->is_interface() && superklass->is_abstract() &&
 43         !superklass->as_instance_klass()->has_subklass()) {
 44       Compile::current()->dependencies()->assert_leaf_type(superklass);
 45       return TypeInt::CC_GT;
 46     }
 47   }
 48 
 49   // FIXME: shouldn't this be encoded in helper methods of the type system (maybe_java_subtype_of() etc.?)
 50   // Similar to logic in CmpPNode::sub()
 51   bool unrelated_classes = false;
 52   // Handle inline type arrays
 53   if (subk->flatten_array() && superk->not_flatten_array()) {
 54     // The subtype is flattened in arrays and the supertype is not flattened in arrays. Must be unrelated.
 55     unrelated_classes = true;
 56   } else if (subk->is_not_flat() && superk->is_flat()) {
 57     // The subtype is a non-flattened array and the supertype is a flattened array. Must be unrelated.
 58     unrelated_classes = true;
 59   } else if (subk->is_not_null_free() && superk->is_null_free()) {
 60     // The subtype is a nullable array and the supertype is null-free array. Must be unrelated.
 61     unrelated_classes = true;
 62   }
 63   if (unrelated_classes) {
 64     TypePtr::PTR jp = sub_t->is_ptr()->join_ptr(super_t->is_ptr()->_ptr);
 65     if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
 66       return TypeInt::CC_GT;
 67     }
 68   }
 69 
 70   if (subk != NULL) {
 71     switch (Compile::current()->static_subtype_check(superk, subk, false)) {
 72       case Compile::SSC_always_false:
 73         return TypeInt::CC_GT;
 74       case Compile::SSC_always_true:
 75         return TypeInt::CC_EQ;
 76       case Compile::SSC_easy_test:
 77       case Compile::SSC_full_test:
 78         break;
 79       default:
 80         ShouldNotReachHere();
 81     }
 82   }
 83 
 84   return bottom_type();
 85 }
 86 
 87 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
 88   Node* obj_or_subklass = in(ObjOrSubKlass);
 89   Node* superklass = in(SuperKlass);
 90 
 91   if (obj_or_subklass == NULL ||
 92       superklass == NULL) {
 93     return NULL;
 94   }
 95 
 96   const Type* sub_t = phase->type(obj_or_subklass);
 97   const Type* super_t = phase->type(superklass);
 98 
 99   if (!super_t->isa_klassptr() ||
100       (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
101     return NULL;
102   }
103 
104   Node* addr = NULL;
105   if (obj_or_subklass->is_DecodeNKlass()) {
106     if (obj_or_subklass->in(1) != NULL &&
107         obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
108       addr = obj_or_subklass->in(1)->in(MemNode::Address);
109     }
110   } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
111     addr = obj_or_subklass->in(MemNode::Address);
112   }
113 
114   if (addr != NULL) {
115     intptr_t con = 0;
116     Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
117     if (con == oopDesc::klass_offset_in_bytes() && obj != NULL) {
118       assert(is_oop(phase, obj), "only for oop input");
119       set_req_X(ObjOrSubKlass, obj, phase);
120       return this;
121     }
122   }
123 
124   // AllocateNode might have more accurate klass input
125   Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
126   if (allocated_klass != NULL) {
127     assert(is_oop(phase, obj_or_subklass), "only for oop input");
128     set_req_X(ObjOrSubKlass, allocated_klass, phase);
129     return this;
130   }
131 
132   // Verify that optimizing the subtype check to a simple code pattern
133   // when possible would not constant fold better
134   assert(verify(phase), "missing Value() optimization");
135 
136   return NULL;
137 }
138 
139 #ifdef ASSERT
140 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
141     const Type* t = phase->type(n);
142     if (!t->isa_oopptr() && t != Type::TOP) {
143       n->dump();
144       t->dump(); tty->cr();
145       return false;
146     }
147     return true;
148 }
149 
150 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
151   if (phase->is_IterGVN()) {
152     phase->is_IterGVN()->_worklist.push(n); // record for cleanup
153   }
154   return n;
155 }
156 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
157   Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
158   record_for_cleanup(cmp, phase);
159 
160   const Type* cmp_t = phase->type(cmp);
161   const Type* t = Value(phase);
162 
163   if (t == cmp_t ||
164       t != cached_t || // previous observations don't hold anymore
165       (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
166     return true;
167   } else {
168     t->dump(); tty->cr();
169     this->dump(2); tty->cr();
170     cmp_t->dump(); tty->cr();
171     subklass->dump(2); tty->cr();
172     tty->print_cr("==============================");
173     phase->C->root()->dump(9999);
174     return false;
175   }
176 }
177 
178 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
179 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
180   Compile* C = phase->C;
181   Node* obj_or_subklass = in(ObjOrSubKlass);
182   Node* superklass = in(SuperKlass);
183 
184   const Type* sub_t = phase->type(obj_or_subklass);
185   const Type* super_t = phase->type(superklass);
186 
187   const TypeKlassPtr* superk = super_t->isa_klassptr();
188   const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
189 
190   if (super_t->singleton() && subk != NULL) {
191     Node* subklass = NULL;
192     if (sub_t->isa_oopptr()) {
193       Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
194       subklass  = phase->transform(LoadKlassNode::make(*phase, NULL, C->immutable_memory(), adr, TypeInstPtr::KLASS));
195       record_for_cleanup(subklass, phase);
196     } else {
197       subklass = obj_or_subklass;
198     }
199 
200     const Type* cached_t = Value(phase); // cache the type to validate consistency
201     switch (C->static_subtype_check(superk, subk)) {
202       case Compile::SSC_easy_test: {
203         return verify_helper(phase, subklass, cached_t);
204       }
205       case Compile::SSC_full_test: {
206         Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
207         Node* chk_off = phase->transform(new LoadINode(NULL, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
208         record_for_cleanup(chk_off, phase);
209 
210         int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
211         bool might_be_cache = (phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con);
212         if (!might_be_cache) {
213           Node* chk_off_X = chk_off;
214 #ifdef _LP64
215           chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
216 #endif
217           Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
218           Node* nkls = phase->transform(LoadKlassNode::make(*phase, NULL, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
219 
220           return verify_helper(phase, nkls, cached_t);
221         }
222         break;
223       }
224       case Compile::SSC_always_false:
225       case Compile::SSC_always_true:
226       default: {
227         break; // nothing to do
228       }
229     }
230   }
231 
232   return true;
233 }
234 #endif