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 return TypeInt::CC_GT;
47 }
48 }
49
50 // FIXME: shouldn't this be encoded in helper methods of the type system (maybe_java_subtype_of() etc.?)
51 // Similar to logic in CmpPNode::sub()
52 bool unrelated_classes = false;
53 // Handle inline type arrays
54 if (subk->flat_in_array() && superk->not_flat_in_array()) {
55 // The subtype is in flat arrays and the supertype is not in flat arrays. Must be unrelated.
56 unrelated_classes = true;
57 } else if (subk->is_not_flat() && superk->is_flat()) {
58 // The subtype is a non-flat array and the supertype is a flat array. Must be unrelated.
59 unrelated_classes = true;
60 } else if (subk->is_not_null_free() && superk->is_null_free()) {
61 // The subtype is a nullable array and the supertype is null-free array. Must be unrelated.
62 unrelated_classes = true;
63 }
64 if (unrelated_classes) {
65 TypePtr::PTR jp = sub_t->is_ptr()->join_ptr(super_t->is_ptr()->_ptr);
66 if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
67 return TypeInt::CC_GT;
68 }
69 }
70
71 if (subk != nullptr) {
72 switch (Compile::current()->static_subtype_check(superk, subk, false)) {
73 case Compile::SSC_always_false:
74 return TypeInt::CC_GT;
75 case Compile::SSC_always_true:
76 return TypeInt::CC_EQ;
77 case Compile::SSC_easy_test:
78 case Compile::SSC_full_test:
79 break;
80 default:
81 ShouldNotReachHere();
82 }
83 }
84
85 return bottom_type();
86 }
87
88 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
89 Node* obj_or_subklass = in(ObjOrSubKlass);
90 Node* superklass = in(SuperKlass);
91
92 if (obj_or_subklass == nullptr ||
93 superklass == nullptr) {
94 return nullptr;
95 }
96
97 const Type* sub_t = phase->type(obj_or_subklass);
98 const Type* super_t = phase->type(superklass);
99
100 if (!super_t->isa_klassptr() ||
101 (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
102 return nullptr;
103 }
104
105 Node* addr = nullptr;
106 if (obj_or_subklass->is_DecodeNKlass()) {
107 if (obj_or_subklass->in(1) != nullptr &&
108 obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
109 addr = obj_or_subklass->in(1)->in(MemNode::Address);
110 }
111 } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
112 addr = obj_or_subklass->in(MemNode::Address);
113 }
114
115 if (addr != nullptr) {
116 intptr_t con = 0;
117 Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
118 if (con == oopDesc::klass_offset_in_bytes() && obj != nullptr) {
119 assert(is_oop(phase, obj), "only for oop input");
120 set_req_X(ObjOrSubKlass, obj, phase);
121 return this;
122 }
123 }
124
125 // AllocateNode might have more accurate klass input
126 Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
127 if (allocated_klass != nullptr) {
128 assert(is_oop(phase, obj_or_subklass), "only for oop input");
129 set_req_X(ObjOrSubKlass, allocated_klass, phase);
130 return this;
131 }
132
133 // Verify that optimizing the subtype check to a simple code pattern
134 // when possible would not constant fold better
135 assert(verify(phase), "missing Value() optimization");
136
137 return nullptr;
138 }
139
140 #ifdef ASSERT
141 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
142 const Type* t = phase->type(n);
143 if (!t->isa_oopptr() && t != Type::TOP) {
144 n->dump();
145 t->dump(); tty->cr();
146 return false;
147 }
148 return true;
149 }
150
151 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
152 if (phase->is_IterGVN()) {
153 phase->is_IterGVN()->_worklist.push(n); // record for cleanup
154 }
155 return n;
156 }
157 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
158 Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
159 record_for_cleanup(cmp, phase);
160
161 const Type* cmp_t = phase->type(cmp);
162 const Type* t = Value(phase);
163
164 if (t == cmp_t ||
165 t != cached_t || // previous observations don't hold anymore
166 (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
167 return true;
168 } else {
169 t->dump(); tty->cr();
170 this->dump(2); tty->cr();
171 cmp_t->dump(); tty->cr();
172 subklass->dump(2); tty->cr();
173 tty->print_cr("==============================");
174 phase->C->root()->dump(9999);
175 return false;
176 }
177 }
178
179 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
180 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
181 Compile* C = phase->C;
182 Node* obj_or_subklass = in(ObjOrSubKlass);
183 Node* superklass = in(SuperKlass);
184
185 const Type* sub_t = phase->type(obj_or_subklass);
186 const Type* super_t = phase->type(superklass);
187
188 const TypeKlassPtr* superk = super_t->isa_klassptr();
189 const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
190
191 if (super_t->singleton() && subk != nullptr) {
192 if (obj_or_subklass->bottom_type() == Type::TOP) {
193 // The bottom type of obj_or_subklass is TOP, despite its recorded type
194 // being an OOP or a klass pointer. This can happen for example in
195 // transient scenarios where obj_or_subklass is a projection of the TOP
196 // node. In such cases, skip verification to avoid violating the contract
197 // of LoadKlassNode::make(). This does not weaken the effect of verify(),
198 // as SubTypeCheck nodes with TOP obj_or_subklass inputs are dead anyway.
199 return true;
200 }
201 const Type* cached_t = Value(phase); // cache the type to validate consistency
202 switch (C->static_subtype_check(superk, subk)) {
203 case Compile::SSC_easy_test: {
204 return verify_helper(phase, load_klass(phase), cached_t);
205 }
206 case Compile::SSC_full_test: {
207 Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
208 Node* chk_off = phase->transform(new LoadINode(nullptr, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
209 record_for_cleanup(chk_off, phase);
210
211 int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
212 bool might_be_cache = (phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con);
213 if (!might_be_cache) {
214 Node* subklass = load_klass(phase);
215 Node* chk_off_X = chk_off;
216 #ifdef _LP64
217 chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
218 #endif
219 Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
220 Node* nkls = phase->transform(LoadKlassNode::make(*phase, nullptr, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
221
222 return verify_helper(phase, nkls, cached_t);
223 }
224 break;
225 }
226 case Compile::SSC_always_false:
227 case Compile::SSC_always_true:
228 default: {
229 break; // nothing to do
230 }
231 }
232 }
233
234 return true;
235 }
236
237 Node* SubTypeCheckNode::load_klass(PhaseGVN* phase) const {
238 Node* obj_or_subklass = in(ObjOrSubKlass);
239 const Type* sub_t = phase->type(obj_or_subklass);
240 Node* subklass = nullptr;
241 if (sub_t->isa_oopptr()) {
242 Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
243 subklass = phase->transform(LoadKlassNode::make(*phase, nullptr, phase->C->immutable_memory(), adr, TypeInstPtr::KLASS));
244 record_for_cleanup(subklass, phase);
245 } else {
246 subklass = obj_or_subklass;
247 }
248 return subklass;
249 }
250 #endif
251
252 uint SubTypeCheckNode::size_of() const {
253 return sizeof(*this);
254 }
255
256 uint SubTypeCheckNode::hash() const {
257 return NO_HASH;
258 }
259
260 #ifndef PRODUCT
261 void SubTypeCheckNode::dump_spec(outputStream* st) const {
262 if (_method != nullptr) {
263 st->print(" profiled at: ");
264 _method->print_short_name(st);
265 st->print(":%d", _bci);
266 }
267 }
268 #endif