1 /*
2 * Copyright (c) 2020, 2025, 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 "opto/addnode.hpp"
26 #include "opto/callnode.hpp"
27 #include "opto/connode.hpp"
28 #include "opto/convertnode.hpp"
29 #include "opto/phaseX.hpp"
30 #include "opto/rootnode.hpp"
31 #include "opto/subnode.hpp"
32 #include "opto/subtypenode.hpp"
33
34 const Type* SubTypeCheckNode::sub(const Type* sub_t, const Type* super_t) const {
35 const TypeKlassPtr* superk = super_t->isa_klassptr();
36 assert(sub_t != Type::TOP && !TypePtr::NULL_PTR->higher_equal(sub_t), "should be not null");
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 != nullptr) {
50 switch (Compile::current()->static_subtype_check(superk, subk, false)) {
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 == nullptr ||
71 superklass == nullptr) {
72 return nullptr;
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 nullptr;
81 }
82
83 Node* addr = nullptr;
84 if (obj_or_subklass->is_DecodeNKlass()) {
85 if (obj_or_subklass->in(1) != nullptr &&
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 != nullptr) {
94 intptr_t con = 0;
95 Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
96 if (con == Type::klass_offset() && obj != nullptr) {
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 != nullptr) {
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 nullptr;
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 != nullptr) {
170 if (obj_or_subklass->bottom_type() == Type::TOP) {
171 // The bottom type of obj_or_subklass is TOP, despite its recorded type
172 // being an OOP or a klass pointer. This can happen for example in
173 // transient scenarios where obj_or_subklass is a projection of the TOP
174 // node. In such cases, skip verification to avoid violating the contract
175 // of LoadKlassNode::make(). This does not weaken the effect of verify(),
176 // as SubTypeCheck nodes with TOP obj_or_subklass inputs are dead anyway.
177 return true;
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, load_klass(phase), 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(nullptr, 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* subklass = load_klass(phase);
193 Node* chk_off_X = chk_off;
194 #ifdef _LP64
195 chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
196 #endif
197 Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
198 Node* nkls = phase->transform(LoadKlassNode::make(*phase, nullptr, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
199
200 return verify_helper(phase, nkls, cached_t);
201 }
202 break;
203 }
204 case Compile::SSC_always_false:
205 case Compile::SSC_always_true:
206 default: {
207 break; // nothing to do
208 }
209 }
210 }
211
212 return true;
213 }
214
215 Node* SubTypeCheckNode::load_klass(PhaseGVN* phase) const {
216 Node* obj_or_subklass = in(ObjOrSubKlass);
217 const Type* sub_t = phase->type(obj_or_subklass);
218 Node* subklass = nullptr;
219 if (sub_t->isa_oopptr()) {
220 Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(Type::klass_offset())));
221 subklass = phase->transform(LoadKlassNode::make(*phase, nullptr, phase->C->immutable_memory(), adr, TypeInstPtr::KLASS));
222 record_for_cleanup(subklass, phase);
223 } else {
224 subklass = obj_or_subklass;
225 }
226 return subklass;
227 }
228 #endif
229
230 uint SubTypeCheckNode::size_of() const {
231 return sizeof(*this);
232 }
233
234 uint SubTypeCheckNode::hash() const {
235 return NO_HASH;
236 }
237
238 #ifndef PRODUCT
239 void SubTypeCheckNode::dump_spec(outputStream* st) const {
240 if (_method != nullptr) {
241 st->print(" profiled at:");
242 _method->print_short_name(st);
243 st->print(":%d", _bci);
244 }
245 }
246 #endif