1 /*
2 * Copyright (c) 2018, 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 #ifndef SHARE_GC_SHARED_C2_BARRIERSETC2_HPP
26 #define SHARE_GC_SHARED_C2_BARRIERSETC2_HPP
27
28 #include "memory/allocation.hpp"
29 #include "oops/accessDecorators.hpp"
30 #include "opto/loopnode.hpp"
31 #include "opto/memnode.hpp"
32 #include "utilities/globalDefinitions.hpp"
33
34 // This means the access is mismatched. This means the value of an access
35 // is not equivalent to the value pointed to by the address.
36 const DecoratorSet C2_MISMATCHED = DECORATOR_LAST << 1;
37 // The access may not be aligned to its natural size.
38 const DecoratorSet C2_UNALIGNED = DECORATOR_LAST << 2;
39 // The atomic cmpxchg is weak, meaning that spurious false negatives are allowed,
40 // but never false positives.
41 const DecoratorSet C2_WEAK_CMPXCHG = DECORATOR_LAST << 3;
42 // This denotes that a load has control dependency.
43 const DecoratorSet C2_CONTROL_DEPENDENT_LOAD = DECORATOR_LAST << 4;
44 // This denotes that a load that must be pinned.
45 const DecoratorSet C2_PINNED_LOAD = DECORATOR_LAST << 5;
46 // This denotes that the access is produced from the sun.misc.Unsafe intrinsics.
47 const DecoratorSet C2_UNSAFE_ACCESS = DECORATOR_LAST << 6;
48 // This denotes that the access mutates state.
49 const DecoratorSet C2_WRITE_ACCESS = DECORATOR_LAST << 7;
50 // This denotes that the access reads state.
51 const DecoratorSet C2_READ_ACCESS = DECORATOR_LAST << 8;
52
53 class GraphKit;
54 class IdealKit;
55 class Node;
56 class Type;
57 class TypePtr;
58 class PhaseMacroExpand;
59
60 // This class wraps a node and a type.
61 class C2AccessValue: public StackObj {
62 protected:
63 Node* _node;
64 const Type* _type;
65
66 public:
67 C2AccessValue(Node* node, const Type* type) :
68 _node(node),
69 _type(type) {}
70
71 Node* node() const { return _node; }
72 const Type* type() const { return _type; }
73
74 void set_node(Node* node) { _node = node; }
75 };
76
77 // This class wraps a node and a pointer type.
78 class C2AccessValuePtr: public C2AccessValue {
79 int _alias_idx;
80
81 public:
82 C2AccessValuePtr(Node* node, const TypePtr* type) :
83 C2AccessValue(node, reinterpret_cast<const Type*>(type)) {}
84
85 const TypePtr* type() const { return reinterpret_cast<const TypePtr*>(_type); }
86 int alias_idx() const { return _alias_idx; }
87 };
88
89 // This class wraps a bunch of context parameters thare are passed around in the
90 // BarrierSetC2 backend hierarchy, for loads and stores, to reduce boiler plate.
91 class C2Access: public StackObj {
92 protected:
93 GraphKit* _kit;
94 DecoratorSet _decorators;
95 BasicType _type;
96 Node* _base;
97 C2AccessValuePtr& _addr;
98 Node* _raw_access;
99
100 void fixup_decorators();
101 void* barrier_set_state() const;
102
103 public:
104 C2Access(GraphKit* kit, DecoratorSet decorators,
105 BasicType type, Node* base, C2AccessValuePtr& addr) :
106 _kit(kit),
107 _decorators(decorators),
108 _type(type),
109 _base(base),
110 _addr(addr),
111 _raw_access(NULL)
112 {
113 fixup_decorators();
114 }
115
116 GraphKit* kit() const { return _kit; }
117 DecoratorSet decorators() const { return _decorators; }
118 Node* base() const { return _base; }
119 C2AccessValuePtr& addr() const { return _addr; }
120 BasicType type() const { return _type; }
121 bool is_oop() const { return _type == T_OBJECT || _type == T_ARRAY; }
122 bool is_raw() const { return (_decorators & AS_RAW) != 0; }
123 Node* raw_access() const { return _raw_access; }
124
125 void set_raw_access(Node* raw_access) { _raw_access = raw_access; }
126 virtual void set_memory() {} // no-op for normal accesses, but not for atomic accesses.
127
128 MemNode::MemOrd mem_node_mo() const;
129 bool needs_cpu_membar() const;
130
131 template <typename T>
132 T barrier_set_state_as() const {
133 return reinterpret_cast<T>(barrier_set_state());
134 }
135 };
136
137 // This class wraps a bunch of context parameters thare are passed around in the
138 // BarrierSetC2 backend hierarchy, for atomic accesses, to reduce boiler plate.
139 class C2AtomicAccess: public C2Access {
140 Node* _memory;
141 uint _alias_idx;
142 bool _needs_pinning;
143
144 public:
145 C2AtomicAccess(GraphKit* kit, DecoratorSet decorators, BasicType type,
146 Node* base, C2AccessValuePtr& addr, uint alias_idx) :
147 C2Access(kit, decorators, type, base, addr),
148 _memory(NULL),
149 _alias_idx(alias_idx),
150 _needs_pinning(true) {}
151
152 // Set the memory node based on the current memory slice.
153 virtual void set_memory();
154
155 Node* memory() const { return _memory; }
156 uint alias_idx() const { return _alias_idx; }
157 bool needs_pinning() const { return _needs_pinning; }
158
159 void set_needs_pinning(bool value) { _needs_pinning = value; }
160 };
161
162 // This is the top-level class for the backend of the Access API in C2.
163 // The top-level class is responsible for performing raw accesses. The
164 // various GC barrier sets inherit from the BarrierSetC2 class to sprinkle
165 // barriers into the accesses.
166 class BarrierSetC2: public CHeapObj<mtGC> {
167 protected:
168 virtual void resolve_address(C2Access& access) const;
169 virtual Node* store_at_resolved(C2Access& access, C2AccessValue& val) const;
170 virtual Node* load_at_resolved(C2Access& access, const Type* val_type) const;
171
172 virtual Node* atomic_cmpxchg_val_at_resolved(C2AtomicAccess& access, Node* expected_val,
173 Node* new_val, const Type* val_type) const;
174 virtual Node* atomic_cmpxchg_bool_at_resolved(C2AtomicAccess& access, Node* expected_val,
175 Node* new_val, const Type* value_type) const;
176 virtual Node* atomic_xchg_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* val_type) const;
177 virtual Node* atomic_add_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* val_type) const;
178
179 public:
180 // This is the entry-point for the backend to perform accesses through the Access API.
181 virtual Node* store_at(C2Access& access, C2AccessValue& val) const;
182 virtual Node* load_at(C2Access& access, const Type* val_type) const;
183
184 virtual Node* atomic_cmpxchg_val_at(C2AtomicAccess& access, Node* expected_val,
185 Node* new_val, const Type* val_type) const;
186 virtual Node* atomic_cmpxchg_bool_at(C2AtomicAccess& access, Node* expected_val,
187 Node* new_val, const Type* val_type) const;
188 virtual Node* atomic_xchg_at(C2AtomicAccess& access, Node* new_val, const Type* value_type) const;
189 virtual Node* atomic_add_at(C2AtomicAccess& access, Node* new_val, const Type* value_type) const;
190
191 virtual void clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const;
192
193 virtual Node* ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const { return NULL; }
194 virtual Node* identity_node(PhaseGVN* phase, Node* n) const { return n; }
195
196 // These are general helper methods used by C2
197 virtual bool array_copy_requires_gc_barriers(BasicType type) const { return false; }
198 virtual void clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const;
199
200 // Support for GC barriers emitted during parsing
201 virtual bool has_load_barriers() const { return false; }
202 virtual bool is_gc_barrier_node(Node* node) const { return false; }
203 virtual Node* step_over_gc_barrier(Node* c) const { return c; }
204
205 // Support for macro expanded GC barriers
206 virtual void register_potential_barrier_node(Node* node) const { }
207 virtual void unregister_potential_barrier_node(Node* node) const { }
208 virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
209 virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {}
210 virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful) const {}
211 virtual void add_users_to_worklist(Unique_Node_List* worklist) const {}
212
213 // Allow barrier sets to have shared state that is preserved across a compilation unit.
214 // This could for example comprise macro nodes to be expanded during macro expansion.
215 virtual void* create_barrier_state(Arena* comp_arena) const { return NULL; }
216 // If the BarrierSetC2 state has kept macro nodes in its compilation unit state to be
217 // expanded later, then now is the time to do so.
218 virtual bool expand_macro_nodes(PhaseMacroExpand* macro) const { return false; }
219 virtual void verify_gc_barriers(bool post_parse) const {}
220 };
221
222 #endif // SHARE_GC_SHARED_C2_BARRIERSETC2_HPP