1 /*
2 * Copyright (c) 2020, 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/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 assert(sub_t != Type::TOP && !TypePtr::NULL_PTR->higher_equal(sub_t), "should be not null");
38 const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
39
40 // Oop can't be a subtype of abstract type that has no subclass.
41 if (sub_t->isa_oopptr() && superk->isa_instklassptr() && superk->klass_is_exact()) {
42 ciKlass* superklass = superk->exact_klass();
43 if (!superklass->is_interface() && superklass->is_abstract() &&
44 !superklass->as_instance_klass()->has_subklass()) {
45 Compile::current()->dependencies()->assert_leaf_type(superklass);
46 if (subk->is_same_java_type_as(superk) && !sub_t->maybe_null()) {
47 // The super_t has no subclasses, and sub_t has the same type and is not null,
48 // hence the check should always evaluate to EQ. However, this is an impossible
49 // situation since super_t is also abstract, and hence sub_t cannot have the
50 // same type and be non-null.
51 // Still, if the non-static method of an abstract class without subclasses is
52 // force-compiled, the Param0 has the self/this pointer with NotNull. This
53 // method would now never be called, because of the leaf-type dependency. Hence,
54 // just for consistency with verification, we return EQ.
55 return TypeInt::CC_EQ;
56 }
57 // subk is either a supertype of superk, or null. In either case, superk is a subtype.
58 return TypeInt::CC_GT;
59 }
60 }
61
62 // FIXME: shouldn't this be encoded in helper methods of the type system (maybe_java_subtype_of() etc.?)
63 // Similar to logic in CmpPNode::sub()
64 bool unrelated_classes = false;
65 // Handle inline type arrays
66 if (subk->flat_in_array() && superk->not_flat_in_array()) {
67 // The subtype is in flat arrays and the supertype is not in flat arrays. Must be unrelated.
68 unrelated_classes = true;
69 } else if (subk->is_not_flat() && superk->is_flat()) {
70 // The subtype is a non-flat array and the supertype is a flat array. Must be unrelated.
71 unrelated_classes = true;
72 } else if (subk->is_not_null_free() && superk->is_null_free()) {
73 // The subtype is a nullable array and the supertype is null-free array. Must be unrelated.
74 unrelated_classes = true;
75 }
76 if (unrelated_classes) {
77 TypePtr::PTR jp = sub_t->is_ptr()->join_ptr(super_t->is_ptr()->_ptr);
78 if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
79 return TypeInt::CC_GT;
80 }
81 }
82
83 if (subk != nullptr) {
84 switch (Compile::current()->static_subtype_check(superk, subk, false)) {
85 case Compile::SSC_always_false:
86 return TypeInt::CC_GT;
87 case Compile::SSC_always_true:
88 return TypeInt::CC_EQ;
89 case Compile::SSC_easy_test:
90 case Compile::SSC_full_test:
91 break;
92 default:
93 ShouldNotReachHere();
94 }
95 }
96
97 return bottom_type();
98 }
99
100 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
101 Node* obj_or_subklass = in(ObjOrSubKlass);
102 Node* superklass = in(SuperKlass);
103
104 if (obj_or_subklass == nullptr ||
105 superklass == nullptr) {
106 return nullptr;
107 }
108
109 const Type* sub_t = phase->type(obj_or_subklass);
110 const Type* super_t = phase->type(superklass);
111
112 if (!super_t->isa_klassptr() ||
113 (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
114 return nullptr;
115 }
116
117 Node* addr = nullptr;
118 if (obj_or_subklass->is_DecodeNKlass()) {
119 if (obj_or_subklass->in(1) != nullptr &&
120 obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
121 addr = obj_or_subklass->in(1)->in(MemNode::Address);
122 }
123 } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
124 addr = obj_or_subklass->in(MemNode::Address);
125 }
126
127 if (addr != nullptr) {
128 intptr_t con = 0;
129 Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
130 if (con == oopDesc::klass_offset_in_bytes() && obj != nullptr) {
131 assert(is_oop(phase, obj), "only for oop input");
132 set_req_X(ObjOrSubKlass, obj, phase);
133 return this;
134 }
135 }
136
137 // AllocateNode might have more accurate klass input
138 Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
139 if (allocated_klass != nullptr) {
140 assert(is_oop(phase, obj_or_subklass), "only for oop input");
141 set_req_X(ObjOrSubKlass, allocated_klass, phase);
142 return this;
143 }
144
145 // Verify that optimizing the subtype check to a simple code pattern
146 // when possible would not constant fold better
147 // TODO 8325106
148 // assert(verify(phase), "missing Value() optimization");
149
150 return nullptr;
151 }
152
153 #ifdef ASSERT
154 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
155 const Type* t = phase->type(n);
156 if (!t->isa_oopptr() && t != Type::TOP) {
157 n->dump();
158 t->dump(); tty->cr();
159 return false;
160 }
161 return true;
162 }
163
164 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
165 if (phase->is_IterGVN()) {
166 phase->is_IterGVN()->_worklist.push(n); // record for cleanup
167 }
168 return n;
169 }
170 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
171 Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
172 record_for_cleanup(cmp, phase);
173
174 const Type* cmp_t = phase->type(cmp);
175 const Type* t = Value(phase);
176
177 if (t == cmp_t ||
178 t != cached_t || // previous observations don't hold anymore
179 (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
180 return true;
181 } else {
182 t->dump(); tty->cr();
183 this->dump(2); tty->cr();
184 cmp_t->dump(); tty->cr();
185 subklass->dump(2); tty->cr();
186 tty->print_cr("==============================");
187 phase->C->root()->dump(9999);
188 return false;
189 }
190 }
191
192 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
193 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
194 Compile* C = phase->C;
195 Node* obj_or_subklass = in(ObjOrSubKlass);
196 Node* superklass = in(SuperKlass);
197
198 const Type* sub_t = phase->type(obj_or_subklass);
199 const Type* super_t = phase->type(superklass);
200
201 const TypeKlassPtr* superk = super_t->isa_klassptr();
202 const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
203
204 if (super_t->singleton() && subk != nullptr) {
205 if (obj_or_subklass->bottom_type() == Type::TOP) {
206 // The bottom type of obj_or_subklass is TOP, despite its recorded type
207 // being an OOP or a klass pointer. This can happen for example in
208 // transient scenarios where obj_or_subklass is a projection of the TOP
209 // node. In such cases, skip verification to avoid violating the contract
210 // of LoadKlassNode::make(). This does not weaken the effect of verify(),
211 // as SubTypeCheck nodes with TOP obj_or_subklass inputs are dead anyway.
212 return true;
213 }
214 const Type* cached_t = Value(phase); // cache the type to validate consistency
215 switch (C->static_subtype_check(superk, subk)) {
216 case Compile::SSC_easy_test: {
217 return verify_helper(phase, load_klass(phase), cached_t);
218 }
219 case Compile::SSC_full_test: {
220 Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
221 Node* chk_off = phase->transform(new LoadINode(nullptr, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
222 record_for_cleanup(chk_off, phase);
223
224 int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
225 bool might_be_cache = (phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con);
226 if (!might_be_cache) {
227 Node* subklass = load_klass(phase);
228 Node* chk_off_X = chk_off;
229 #ifdef _LP64
230 chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
231 #endif
232 Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
233 Node* nkls = phase->transform(LoadKlassNode::make(*phase, nullptr, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
234
235 return verify_helper(phase, nkls, cached_t);
236 }
237 break;
238 }
239 case Compile::SSC_always_false:
240 case Compile::SSC_always_true:
241 default: {
242 break; // nothing to do
243 }
244 }
245 }
246
247 return true;
248 }
249
250 Node* SubTypeCheckNode::load_klass(PhaseGVN* phase) const {
251 Node* obj_or_subklass = in(ObjOrSubKlass);
252 const Type* sub_t = phase->type(obj_or_subklass);
253 Node* subklass = nullptr;
254 if (sub_t->isa_oopptr()) {
255 Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
256 subklass = phase->transform(LoadKlassNode::make(*phase, nullptr, phase->C->immutable_memory(), adr, TypeInstPtr::KLASS));
257 record_for_cleanup(subklass, phase);
258 } else {
259 subklass = obj_or_subklass;
260 }
261 return subklass;
262 }
263 #endif
264
265 uint SubTypeCheckNode::size_of() const {
266 return sizeof(*this);
267 }
268
269 uint SubTypeCheckNode::hash() const {
270 return NO_HASH;
271 }
272
273 #ifndef PRODUCT
274 void SubTypeCheckNode::dump_spec(outputStream* st) const {
275 if (_method != nullptr) {
276 st->print(" profiled at: ");
277 _method->print_short_name(st);
278 st->print(":%d", _bci);
279 }
280 }
281 #endif