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   if (subk != NULL) {
 50     switch (Compile::current()->static_subtype_check(superk, subk)) {
 51       case Compile::SSC_always_false:
 52         return TypeInt::CC_GT;
 53       case Compile::SSC_always_true:
 54         return TypeInt::CC_EQ;
 55       case Compile::SSC_easy_test:
 56       case Compile::SSC_full_test:
 57         break;
 58       default:
 59         ShouldNotReachHere();
 60     }
 61   }
 62 
 63   return bottom_type();
 64 }
 65 
 66 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
 67   Node* obj_or_subklass = in(ObjOrSubKlass);
 68   Node* superklass = in(SuperKlass);
 69 
 70   if (obj_or_subklass == NULL ||
 71       superklass == NULL) {
 72     return NULL;
 73   }
 74 
 75   const Type* sub_t = phase->type(obj_or_subklass);
 76   const Type* super_t = phase->type(superklass);
 77 
 78   if (!super_t->isa_klassptr() ||
 79       (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
 80     return NULL;
 81   }
 82 
 83   Node* addr = NULL;
 84   if (obj_or_subklass->is_DecodeNKlass()) {
 85     if (obj_or_subklass->in(1) != NULL &&
 86         obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
 87       addr = obj_or_subklass->in(1)->in(MemNode::Address);
 88     }
 89   } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
 90     addr = obj_or_subklass->in(MemNode::Address);
 91   }
 92 
 93   if (addr != NULL) {
 94     intptr_t con = 0;
 95     Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
 96     if (con == oopDesc::klass_offset_in_bytes() && obj != NULL) {
 97       assert(is_oop(phase, obj), "only for oop input");
 98       set_req_X(ObjOrSubKlass, obj, phase);
 99       return this;
100     }
101   }
102 
103   // AllocateNode might have more accurate klass input
104   Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
105   if (allocated_klass != NULL) {
106     assert(is_oop(phase, obj_or_subklass), "only for oop input");
107     set_req_X(ObjOrSubKlass, allocated_klass, phase);
108     return this;
109   }
110 
111   // Verify that optimizing the subtype check to a simple code pattern
112   // when possible would not constant fold better
113   assert(verify(phase), "missing Value() optimization");
114 
115   return NULL;
116 }
117 
118 #ifdef ASSERT
119 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
120     const Type* t = phase->type(n);
121     if (!t->isa_oopptr() && t != Type::TOP) {
122       n->dump();
123       t->dump(); tty->cr();
124       return false;
125     }
126     return true;
127 }
128 
129 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
130   if (phase->is_IterGVN()) {
131     phase->is_IterGVN()->_worklist.push(n); // record for cleanup
132   }
133   return n;
134 }
135 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
136   Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
137   record_for_cleanup(cmp, phase);
138 
139   const Type* cmp_t = phase->type(cmp);
140   const Type* t = Value(phase);
141 
142   if (t == cmp_t ||
143       t != cached_t || // previous observations don't hold anymore
144       (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
145     return true;
146   } else {
147     t->dump(); tty->cr();
148     this->dump(2); tty->cr();
149     cmp_t->dump(); tty->cr();
150     subklass->dump(2); tty->cr();
151     tty->print_cr("==============================");
152     phase->C->root()->dump(9999);
153     return false;
154   }
155 }
156 
157 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
158 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
159   Compile* C = phase->C;
160   Node* obj_or_subklass = in(ObjOrSubKlass);
161   Node* superklass = in(SuperKlass);
162 
163   const Type* sub_t = phase->type(obj_or_subklass);
164   const Type* super_t = phase->type(superklass);
165 
166   const TypeKlassPtr* superk = super_t->isa_klassptr();
167   const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
168 
169   if (super_t->singleton() && subk != NULL) {
170     Node* subklass = NULL;
171     if (sub_t->isa_oopptr()) {
172       Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
173       subklass  = phase->transform(LoadKlassNode::make(*phase, NULL, C->immutable_memory(), adr, TypeInstPtr::KLASS));
174       record_for_cleanup(subklass, phase);
175     } else {
176       subklass = obj_or_subklass;
177     }
178 
179     const Type* cached_t = Value(phase); // cache the type to validate consistency
180     switch (C->static_subtype_check(superk, subk)) {
181       case Compile::SSC_easy_test: {
182         return verify_helper(phase, subklass, cached_t);
183       }
184       case Compile::SSC_full_test: {
185         Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
186         Node* chk_off = phase->transform(new LoadINode(NULL, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
187         record_for_cleanup(chk_off, phase);
188 
189         int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
190         bool might_be_cache = (phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con);
191         if (!might_be_cache) {
192           Node* chk_off_X = chk_off;
193 #ifdef _LP64
194           chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
195 #endif
196           Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
197           Node* nkls = phase->transform(LoadKlassNode::make(*phase, NULL, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
198 
199           return verify_helper(phase, nkls, cached_t);
200         }
201         break;
202       }
203       case Compile::SSC_always_false:
204       case Compile::SSC_always_true:
205       default: {
206         break; // nothing to do
207       }
208     }
209   }
210 
211   return true;
212 }
213 #endif