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 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->flatten_array() && superk->not_flatten_array()) {
54 // The subtype is flattened in arrays and the supertype is not flattened in arrays. Must be unrelated.
55 unrelated_classes = true;
56 } else if (subk->is_not_flat() && superk->is_flat()) {
57 // The subtype is a non-flattened array and the supertype is a flattened 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 if (subk != nullptr) {
71 switch (Compile::current()->static_subtype_check(superk, subk, false)) {
72 case Compile::SSC_always_false:
73 return TypeInt::CC_GT;
74 case Compile::SSC_always_true:
75 return TypeInt::CC_EQ;
76 case Compile::SSC_easy_test:
77 case Compile::SSC_full_test:
78 break;
79 default:
80 ShouldNotReachHere();
81 }
82 }
83
84 return bottom_type();
85 }
86
87 Node *SubTypeCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
88 Node* obj_or_subklass = in(ObjOrSubKlass);
89 Node* superklass = in(SuperKlass);
90
91 if (obj_or_subklass == nullptr ||
92 superklass == nullptr) {
93 return nullptr;
94 }
95
96 const Type* sub_t = phase->type(obj_or_subklass);
97 const Type* super_t = phase->type(superklass);
98
99 if (!super_t->isa_klassptr() ||
100 (!sub_t->isa_klassptr() && !sub_t->isa_oopptr())) {
101 return nullptr;
102 }
103
104 Node* addr = nullptr;
105 if (obj_or_subklass->is_DecodeNKlass()) {
106 if (obj_or_subklass->in(1) != nullptr &&
107 obj_or_subklass->in(1)->Opcode() == Op_LoadNKlass) {
108 addr = obj_or_subklass->in(1)->in(MemNode::Address);
109 }
110 } else if (obj_or_subklass->Opcode() == Op_LoadKlass) {
111 addr = obj_or_subklass->in(MemNode::Address);
112 }
113
114 if (addr != nullptr) {
115 intptr_t con = 0;
116 Node* obj = AddPNode::Ideal_base_and_offset(addr, phase, con);
117 if (con == oopDesc::klass_offset_in_bytes() && obj != nullptr) {
118 assert(is_oop(phase, obj), "only for oop input");
119 set_req_X(ObjOrSubKlass, obj, phase);
120 return this;
121 }
122 }
123
124 // AllocateNode might have more accurate klass input
125 Node* allocated_klass = AllocateNode::Ideal_klass(obj_or_subklass, phase);
126 if (allocated_klass != nullptr) {
127 assert(is_oop(phase, obj_or_subklass), "only for oop input");
128 set_req_X(ObjOrSubKlass, allocated_klass, phase);
129 return this;
130 }
131
132 // Verify that optimizing the subtype check to a simple code pattern
133 // when possible would not constant fold better
134 assert(verify(phase), "missing Value() optimization");
135
136 return nullptr;
137 }
138
139 #ifdef ASSERT
140 bool SubTypeCheckNode::is_oop(PhaseGVN* phase, Node* n) {
141 const Type* t = phase->type(n);
142 if (!t->isa_oopptr() && t != Type::TOP) {
143 n->dump();
144 t->dump(); tty->cr();
145 return false;
146 }
147 return true;
148 }
149
150 static Node* record_for_cleanup(Node* n, PhaseGVN* phase) {
151 if (phase->is_IterGVN()) {
152 phase->is_IterGVN()->_worklist.push(n); // record for cleanup
153 }
154 return n;
155 }
156 bool SubTypeCheckNode::verify_helper(PhaseGVN* phase, Node* subklass, const Type* cached_t) {
157 Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
158 record_for_cleanup(cmp, phase);
159
160 const Type* cmp_t = phase->type(cmp);
161 const Type* t = Value(phase);
162
163 if (t == cmp_t ||
164 t != cached_t || // previous observations don't hold anymore
165 (cmp_t != TypeInt::CC_GT && cmp_t != TypeInt::CC_EQ)) {
166 return true;
167 } else {
168 t->dump(); tty->cr();
169 this->dump(2); tty->cr();
170 cmp_t->dump(); tty->cr();
171 subklass->dump(2); tty->cr();
172 tty->print_cr("==============================");
173 phase->C->root()->dump(9999);
174 return false;
175 }
176 }
177
178 // Verify that optimizing the subtype check to a simple code pattern when possible would not constant fold better.
179 bool SubTypeCheckNode::verify(PhaseGVN* phase) {
180 Compile* C = phase->C;
181 Node* obj_or_subklass = in(ObjOrSubKlass);
182 Node* superklass = in(SuperKlass);
183
184 const Type* sub_t = phase->type(obj_or_subklass);
185 const Type* super_t = phase->type(superklass);
186
187 const TypeKlassPtr* superk = super_t->isa_klassptr();
188 const TypeKlassPtr* subk = sub_t->isa_klassptr() ? sub_t->is_klassptr() : sub_t->is_oopptr()->as_klass_type();
189
190 if (super_t->singleton() && subk != nullptr) {
191 const Type* cached_t = Value(phase); // cache the type to validate consistency
192 switch (C->static_subtype_check(superk, subk)) {
193 case Compile::SSC_easy_test: {
194 return verify_helper(phase, load_klass(phase), cached_t);
195 }
196 case Compile::SSC_full_test: {
197 Node* p1 = phase->transform(new AddPNode(superklass, superklass, phase->MakeConX(in_bytes(Klass::super_check_offset_offset()))));
198 Node* chk_off = phase->transform(new LoadINode(nullptr, C->immutable_memory(), p1, phase->type(p1)->is_ptr(), TypeInt::INT, MemNode::unordered));
199 record_for_cleanup(chk_off, phase);
200
201 int cacheoff_con = in_bytes(Klass::secondary_super_cache_offset());
202 bool might_be_cache = (phase->find_int_con(chk_off, cacheoff_con) == cacheoff_con);
203 if (!might_be_cache) {
204 Node* subklass = load_klass(phase);
205 Node* chk_off_X = chk_off;
206 #ifdef _LP64
207 chk_off_X = phase->transform(new ConvI2LNode(chk_off_X));
208 #endif
209 Node* p2 = phase->transform(new AddPNode(subklass, subklass, chk_off_X));
210 Node* nkls = phase->transform(LoadKlassNode::make(*phase, nullptr, C->immutable_memory(), p2, phase->type(p2)->is_ptr(), TypeInstKlassPtr::OBJECT_OR_NULL));
211
212 return verify_helper(phase, nkls, cached_t);
213 }
214 break;
215 }
216 case Compile::SSC_always_false:
217 case Compile::SSC_always_true:
218 default: {
219 break; // nothing to do
220 }
221 }
222 }
223
224 return true;
225 }
226
227 Node* SubTypeCheckNode::load_klass(PhaseGVN* phase) const {
228 Node* obj_or_subklass = in(ObjOrSubKlass);
229 const Type* sub_t = phase->type(obj_or_subklass);
230 Node* subklass = nullptr;
231 if (sub_t->isa_oopptr()) {
232 Node* adr = phase->transform(new AddPNode(obj_or_subklass, obj_or_subklass, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
233 subklass = phase->transform(LoadKlassNode::make(*phase, nullptr, phase->C->immutable_memory(), adr, TypeInstPtr::KLASS));
234 record_for_cleanup(subklass, phase);
235 } else {
236 subklass = obj_or_subklass;
237 }
238 return subklass;
239 }
240
241 #endif