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