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 // 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->flat_in_array() && superk->not_flat_in_array_inexact()) {
54 // The subtype is in flat arrays and the supertype is not in flat arrays and no subklass can be. Must be unrelated.
55 unrelated_classes = true;
56 } else if (subk->is_not_flat() && superk->is_flat()) {
57 // The subtype is a non-flat array and the supertype is a flat 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 switch (Compile::current()->static_subtype_check(superk, subk, false)) {
71 case Compile::SSC_always_false:
72 return TypeInt::CC_GT;
73 case Compile::SSC_always_true:
74 return TypeInt::CC_EQ;
75 case Compile::SSC_easy_test:
76 case Compile::SSC_full_test:
77 break;
78 default:
79 ShouldNotReachHere();
80 }
81
82 return bottom_type();
83 }
84
85 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
86 Node* obj_or_subklass = in(ObjOrSubKlass);
87 Node* superklass = in(SuperKlass);
88
89 if (obj_or_subklass == nullptr ||
90 superklass == nullptr) {
91 return nullptr;
92 }
93
94 const Type* sub_t = phase->type(obj_or_subklass);
95 const Type* super_t = phase->type(superklass);
96
97 if (!super_t->isa_klassptr() ||
98 (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
99 return nullptr;
100 }
101
102 Node* addr = nullptr;
103 if (obj_or_subklass->is_DecodeNKlass()) {
104 if (obj_or_subklass->in(1) != nullptr &&
105 obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
106 addr = obj_or_subklass->in(1)->in(MemNode::Address);
107 }
108 } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
109 addr = obj_or_subklass->in(MemNode::Address);
110 }
111
112 if (addr != nullptr) {
113 intptr_t con = 0;
114 Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
115 if (con == oopDesc::klass_offset_in_bytes() && obj != nullptr) {
116 assert(is_oop(phase, obj), "only for oop input");
117 set_req_X(ObjOrSubKlass, obj, phase);
118 return this;
119 }
120 }
121
122 // AllocateNode might have more accurate klass input
123 Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
124 if (allocated_klass != nullptr) {
125 assert(is_oop(phase, obj_or_subklass), "only for oop input");
126 set_req_X(ObjOrSubKlass, allocated_klass, phase);
127 return this;
128 }
129
130 // Verify that optimizing the subtype check to a simple code pattern
131 // when possible would not constant fold better
132 assert(verify(phase), "missing Value() optimization");
133
134 return nullptr;
135 }
136
137 #ifdef ASSERT
138 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
139 const Type* t = phase->type(n);
140 if (!t->isa_oopptr() && t != Type::TOP) {
141 n->dump();
142 t->dump(); tty->cr();
143 return false;
144 }
145 return true;
146 }
147
148 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
149 if (phase->is_IterGVN()) {
150 phase->is_IterGVN()->_worklist.push(n); // record for cleanup
151 }
152 return n;
153 }
154 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
155 Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
156 record_for_cleanup(cmp, phase);
157
158 const Type* cmp_t = phase->type(cmp);
159 const Type* t = Value(phase);
160
161 if (t == cmp_t ||
162 t != cached_t || // previous observations don't hold anymore
163 (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
164 return true;
165 } else {
166 t->dump(); tty->cr();
167 this->dump(2); tty->cr();
168 cmp_t->dump(); tty->cr();
169 subklass->dump(2); tty->cr();
170 tty->print_cr("==============================");
171 phase->C->root()->dump(9999);
172 return false;
173 }
174 }
175
176 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
177 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
178 Compile* C = phase->C;
179 Node* obj_or_subklass = in(ObjOrSubKlass);
180 Node* superklass = in(SuperKlass);
181
182 const Type* sub_t = phase->type(obj_or_subklass);
183 const Type* super_t = phase->type(superklass);
184
185 const TypeKlassPtr* superk = super_t->isa_klassptr();
186 const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
187
188 if (super_t->singleton() && subk != nullptr) {
189 if (obj_or_subklass->bottom_type() == Type::TOP) {
190 // The bottom type of obj_or_subklass is TOP, despite its recorded type
191 // being an OOP or a klass pointer. This can happen for example in
192 // transient scenarios where obj_or_subklass is a projection of the TOP
193 // node. In such cases, skip verification to avoid violating the contract
194 // of LoadKlassNode::make(). This does not weaken the effect of verify(),
195 // as SubTypeCheck nodes with TOP obj_or_subklass inputs are dead anyway.
196 return true;
197 }
198 const Type* cached_t = Value(phase); // cache the type to validate consistency
199 switch (C->static_subtype_check(superk, subk)) {
200 case Compile::SSC_easy_test: {
201 return verify_helper(phase, load_klass(phase), cached_t);
202 }
203 case Compile::SSC_full_test: {
204 Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
205 Node* chk_off = phase->transform(new LoadINode(nullptr, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
206 record_for_cleanup(chk_off, phase);
207
208 int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
209 bool might_be_cache = (phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con);
210 if (!might_be_cache) {
211 Node* subklass = load_klass(phase);
212 Node* chk_off_X = chk_off;
213 #ifdef _LP64
214 chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
215 #endif
216 Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
217 Node* nkls = phase->transform(LoadKlassNode::make(*phase, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
218
219 return verify_helper(phase, nkls, cached_t);
220 }
221 break;
222 }
223 case Compile::SSC_always_false:
224 case Compile::SSC_always_true:
225 default: {
226 break; // nothing to do
227 }
228 }
229 }
230
231 return true;
232 }
233
234 Node* SubTypeCheckNode::load_klass(PhaseGVN* phase) const {
235 Node* obj_or_subklass = in(ObjOrSubKlass);
236 const Type* sub_t = phase->type(obj_or_subklass);
237 Node* subklass = nullptr;
238 if (sub_t->isa_oopptr()) {
239 Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
240 subklass = phase->transform(LoadKlassNode::make(*phase, phase->C->immutable_memory(), adr, TypeInstPtr::KLASS));
241 record_for_cleanup(subklass, phase);
242 } else {
243 subklass = obj_or_subklass;
244 }
245 return subklass;
246 }
247 #endif
248
249 uint SubTypeCheckNode::size_of() const {
250 return sizeof(*this);
251 }
252
253 uint SubTypeCheckNode::hash() const {
254 return NO_HASH;
255 }
256
257 #ifndef PRODUCT
258 void SubTypeCheckNode::dump_spec(outputStream* st) const {
259 if (_method != nullptr) {
260 st->print(" profiled at:");
261 _method->print_short_name(st);
262 st->print(":%d", _bci);
263 }
264 }
265 #endif