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* super_klass_type = super_t->isa_klassptr();
36 assert(sub_t != Type::TOP && !TypePtr::NULL_PTR->higher_equal(sub_t), "should be not null");
37 const TypeKlassPtr* sub_klass_type = 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() && super_klass_type->isa_instklassptr() && super_klass_type->klass_is_exact()) {
41 ciKlass* superklass = super_klass_type->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
53 // Handle inline type arrays
54 //
55 // The super klass can be an exact non-array klass constant which is known to be not flat in array (e.g. Object)
56 // while the sub klass could very well be flat in array:
57 //
58 // MyValue <: Object:exact
59 // flat in array not flat in array
60 //
61 // We therefore first cast the super klass to inexact (if the class is not final itself) and recompute the flat in
62 // array property for the super klass (all done in cast_to_exactness()) in order to check whether the sub klass is
63 // flat in array and the super klass is not flat in array. If that's the case, the classes must be unrelated.
64 const TypeKlassPtr* super_klass_type_for_flat_in_array = super_klass_type;
65 if (super_klass_type->isa_instklassptr()) {
66 // Only relevant for TypeInstKlassPtr. TypeAryKlassPtr will always be not flat in array.
67 super_klass_type_for_flat_in_array = super_klass_type->cast_to_exactness(false);
68 }
69
70 if (sub_klass_type->is_flat_in_array() && super_klass_type_for_flat_in_array->is_not_flat_in_array()) {
71 // The subtype is in flat arrays and the supertype is not in flat arrays and no subklass can be. Must be unrelated.
72 unrelated_classes = true;
73 } else if (sub_klass_type->is_not_flat() && super_klass_type->is_flat()) {
74 // The subtype is a non-flat array and the supertype is a flat array. Must be unrelated.
75 unrelated_classes = true;
76 } else if (sub_klass_type->is_not_null_free() && super_klass_type->is_null_free()) {
77 // The subtype is a nullable array and the supertype is null-free array. Must be unrelated.
78 unrelated_classes = true;
79 }
80 if (unrelated_classes) {
81 TypePtr::PTR jp = sub_t->is_ptr()->join_ptr(super_t->is_ptr()->_ptr);
82 if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
83 return TypeInt::CC_GT;
84 }
85 }
86
87 switch (Compile::current()->static_subtype_check(super_klass_type, sub_klass_type, false)) {
88 case Compile::SSC_always_false:
89 return TypeInt::CC_GT;
90 case Compile::SSC_always_true:
91 return TypeInt::CC_EQ;
92 case Compile::SSC_easy_test:
93 case Compile::SSC_full_test:
94 break;
95 default:
96 ShouldNotReachHere();
97 }
98
99 return bottom_type();
100 }
101
102 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
103 Node* obj_or_subklass = in(ObjOrSubKlass);
104 Node* superklass = in(SuperKlass);
105
106 if (obj_or_subklass == nullptr ||
107 superklass == nullptr) {
108 return nullptr;
109 }
110
111 const Type* sub_t = phase->type(obj_or_subklass);
112 const Type* super_t = phase->type(superklass);
113
114 if (!super_t->isa_klassptr() ||
115 (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
116 return nullptr;
117 }
118
119 Node* addr = nullptr;
120 if (obj_or_subklass->is_DecodeNKlass()) {
121 if (obj_or_subklass->in(1) != nullptr &&
122 obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
123 addr = obj_or_subklass->in(1)->in(MemNode::Address);
124 }
125 } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
126 addr = obj_or_subklass->in(MemNode::Address);
127 }
128
129 if (addr != nullptr) {
130 intptr_t con = 0;
131 Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
132 if (con == oopDesc::klass_offset_in_bytes() && obj != nullptr) {
133 assert(is_oop(phase, obj), "only for oop input");
134 set_req_X(ObjOrSubKlass, obj, phase);
135 return this;
136 }
137 }
138
139 // AllocateNode might have more accurate klass input
140 Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
141 if (allocated_klass != nullptr) {
142 assert(is_oop(phase, obj_or_subklass), "only for oop input");
143 set_req_X(ObjOrSubKlass, allocated_klass, phase);
144 return this;
145 }
146
147 // Verify that optimizing the subtype check to a simple code pattern
148 // when possible would not constant fold better
149 assert(verify(phase), "missing Value() optimization");
150
151 return nullptr;
152 }
153
154 #ifdef ASSERT
155 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
156 const Type* t = phase->type(n);
157 if (!t->isa_oopptr() && t != Type::TOP) {
158 n->dump();
159 t->dump(); tty->cr();
160 return false;
161 }
162 return true;
163 }
164
165 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
166 if (phase->is_IterGVN()) {
167 phase->is_IterGVN()->_worklist.push(n); // record for cleanup
168 }
169 return n;
170 }
171 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
172 Node* cmp_orig = new CmpPNode(subklass, in(SuperKlass));
173 Node* cmp = phase->transform(cmp_orig);
174 record_for_cleanup(cmp, phase);
175
176 const Type* cmp_t = phase->type(cmp);
177 const Type* t = Value(phase);
178
179 if (t == cmp_t ||
180 t != cached_t || // previous observations don't hold anymore
181 (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
182 return true;
183 } else {
184 t->dump(); tty->cr();
185 this->dump(2); tty->cr();
186 tty->print_cr("VS.\n");
187 cmp_t->dump(); tty->cr();
188 cmp_orig->dump(2); tty->cr();
189 tty->print_cr("==============================\n");
190 phase->C->root()->dump(9999);
191 return false;
192 }
193 }
194
195 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
196 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
197 Compile* C = phase->C;
198 Node* obj_or_subklass = in(ObjOrSubKlass);
199 Node* superklass = in(SuperKlass);
200
201 const Type* sub_t = phase->type(obj_or_subklass);
202 const Type* super_t = phase->type(superklass);
203
204 const TypeKlassPtr* superk = super_t->isa_klassptr();
205 const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
206
207 if (super_t->singleton() && subk != nullptr) {
208 if (obj_or_subklass->bottom_type() == Type::TOP) {
209 // The bottom type of obj_or_subklass is TOP, despite its recorded type
210 // being an OOP or a klass pointer. This can happen for example in
211 // transient scenarios where obj_or_subklass is a projection of the TOP
212 // node. In such cases, skip verification to avoid violating the contract
213 // of LoadKlassNode::make(). This does not weaken the effect of verify(),
214 // as SubTypeCheck nodes with TOP obj_or_subklass inputs are dead anyway.
215 return true;
216 }
217 const Type* cached_t = Value(phase); // cache the type to validate consistency
218 switch (C->static_subtype_check(superk, subk)) {
219 case Compile::SSC_easy_test: {
220 return verify_helper(phase, load_klass(phase), cached_t);
221 }
222 case Compile::SSC_full_test: {
223 Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
224 Node* chk_off = phase->transform(new LoadINode(nullptr, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
225 record_for_cleanup(chk_off, phase);
226
227 int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
228 bool might_be_cache = phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con;
229 if (!might_be_cache) {
230 Node* subklass = load_klass(phase);
231 Node* chk_off_X = chk_off;
232 #ifdef _LP64
233 chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
234 #endif
235 Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
236 Node* nkls = phase->transform(LoadKlassNode::make(*phase, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
237
238 return verify_helper(phase, nkls, cached_t);
239 }
240 break;
241 }
242 case Compile::SSC_always_false:
243 case Compile::SSC_always_true:
244 default: {
245 break; // nothing to do
246 }
247 }
248 }
249
250 return true;
251 }
252
253 Node* SubTypeCheckNode::load_klass(PhaseGVN* phase) const {
254 Node* obj_or_subklass = in(ObjOrSubKlass);
255 const Type* sub_t = phase->type(obj_or_subklass);
256 Node* subklass = nullptr;
257 if (sub_t->isa_oopptr()) {
258 Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
259 subklass = phase->transform(LoadKlassNode::make(*phase, phase->C->immutable_memory(), adr, TypeInstPtr::KLASS));
260 record_for_cleanup(subklass, phase);
261 } else {
262 subklass = obj_or_subklass;
263 }
264 return subklass;
265 }
266 #endif
267
268 uint SubTypeCheckNode::size_of() const {
269 return sizeof(*this);
270 }
271
272 uint SubTypeCheckNode::hash() const {
273 return NO_HASH;
274 }
275
276 #ifndef PRODUCT
277 void SubTypeCheckNode::dump_spec(outputStream* st) const {
278 if (_method != nullptr) {
279 st->print(" profiled at:");
280 _method->print_short_name(st);
281 st->print(":%d", _bci);
282 }
283 }
284 #endif