1 /*
2 * Copyright (c) 2018, 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.
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20 * or visit www.oracle.com if you need additional information or have any
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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/machnode.hpp"
32 #include "opto/matcher.hpp"
33 #include "opto/memnode.hpp"
34 #include "utilities/globalDefinitions.hpp"
35
36 // This means the access is mismatched. This means the value of an access
37 // is not equivalent to the value pointed to by the address.
38 const DecoratorSet C2_MISMATCHED = DECORATOR_LAST << 1;
39 // The access may not be aligned to its natural size.
40 const DecoratorSet C2_UNALIGNED = DECORATOR_LAST << 2;
41 // The atomic cmpxchg is weak, meaning that spurious false negatives are allowed,
42 // but never false positives.
43 const DecoratorSet C2_WEAK_CMPXCHG = DECORATOR_LAST << 3;
44 // This denotes that a load has control dependency.
45 const DecoratorSet C2_CONTROL_DEPENDENT_LOAD = DECORATOR_LAST << 4;
46 // This denotes that a load that must be pinned, but may float above safepoints.
47 const DecoratorSet C2_UNKNOWN_CONTROL_LOAD = DECORATOR_LAST << 5;
48 // This denotes that the access is produced from the sun.misc.Unsafe intrinsics.
49 const DecoratorSet C2_UNSAFE_ACCESS = DECORATOR_LAST << 6;
50 // This denotes that the access mutates state.
51 const DecoratorSet C2_WRITE_ACCESS = DECORATOR_LAST << 7;
52 // This denotes that the access reads state.
53 const DecoratorSet C2_READ_ACCESS = DECORATOR_LAST << 8;
54 // A nearby allocation?
55 const DecoratorSet C2_TIGHTLY_COUPLED_ALLOC = DECORATOR_LAST << 9;
56 // Loads and stores from an arraycopy being optimized
57 const DecoratorSet C2_ARRAY_COPY = DECORATOR_LAST << 10;
58 // Loads from immutable memory
59 const DecoratorSet C2_IMMUTABLE_MEMORY = DECORATOR_LAST << 11;
60
61 class Compile;
62 class ConnectionGraph;
63 class GraphKit;
64 class IdealKit;
65 class Node;
66 class PhaseGVN;
67 class PhaseIdealLoop;
68 class PhaseMacroExpand;
69 class Type;
70 class TypePtr;
71 class Unique_Node_List;
72
73 // This class wraps a node and a type.
74 class C2AccessValue: public StackObj {
75 protected:
76 Node* _node;
77 const Type* _type;
78
79 public:
80 C2AccessValue(Node* node, const Type* type) :
81 _node(node),
82 _type(type) {}
83
84 Node* node() const { return _node; }
85 const Type* type() const { return _type; }
86
87 void set_node(Node* node) { _node = node; }
88 };
89
90 // This class wraps a node and a pointer type.
91 class C2AccessValuePtr: public C2AccessValue {
92
93 public:
94 C2AccessValuePtr(Node* node, const TypePtr* type) :
95 C2AccessValue(node, reinterpret_cast<const Type*>(type)) {}
96
97 const TypePtr* type() const { return reinterpret_cast<const TypePtr*>(_type); }
98 };
99
100 // This class wraps a bunch of context parameters that are passed around in the
101 // BarrierSetC2 backend hierarchy, for loads and stores, to reduce boiler plate.
102 class C2Access: public StackObj {
103 protected:
104 DecoratorSet _decorators;
105 Node* _base;
106 C2AccessValuePtr& _addr;
107 Node* _raw_access;
108 BasicType _type;
109 uint8_t _barrier_data;
110
111 void fixup_decorators();
112
113 public:
114 C2Access(DecoratorSet decorators,
115 BasicType type, Node* base, C2AccessValuePtr& addr) :
116 _decorators(decorators),
117 _base(base),
118 _addr(addr),
119 _raw_access(nullptr),
120 _type(type),
121 _barrier_data(0)
122 {}
123
124 DecoratorSet decorators() const { return _decorators; }
125 Node* base() const { return _base; }
126 C2AccessValuePtr& addr() const { return _addr; }
127 BasicType type() const { return _type; }
128 bool is_oop() const { return is_reference_type(_type); }
129 bool is_raw() const { return (_decorators & AS_RAW) != 0; }
130 Node* raw_access() const { return _raw_access; }
131
132 uint8_t barrier_data() const { return _barrier_data; }
133 void set_barrier_data(uint8_t data) { _barrier_data = data; }
134
135 void set_raw_access(Node* raw_access) { _raw_access = raw_access; }
136 virtual void set_memory() {} // no-op for normal accesses, but not for atomic accesses.
137
138 MemNode::MemOrd mem_node_mo() const;
139 bool needs_cpu_membar() const;
140
141 virtual PhaseGVN& gvn() const = 0;
142 virtual bool is_parse_access() const { return false; }
143 virtual bool is_opt_access() const { return false; }
144 };
145
146 // C2Access for parse time calls to the BarrierSetC2 backend.
147 class C2ParseAccess: public C2Access {
148 protected:
149 GraphKit* _kit;
150 Node* _ctl;
151
152 void* barrier_set_state() const;
153
154 public:
155 C2ParseAccess(GraphKit* kit, DecoratorSet decorators,
156 BasicType type, Node* base, C2AccessValuePtr& addr,
157 Node* ctl = nullptr) :
158 C2Access(decorators, type, base, addr),
159 _kit(kit),
160 _ctl(ctl) {
161 fixup_decorators();
162 }
163
164 GraphKit* kit() const { return _kit; }
165 Node* control() const;
166
167 virtual PhaseGVN& gvn() const;
168 virtual bool is_parse_access() const { return true; }
169 };
170
171 // This class wraps a bunch of context parameters that are passed around in the
172 // BarrierSetC2 backend hierarchy, for atomic accesses, to reduce boiler plate.
173 class C2AtomicParseAccess: public C2ParseAccess {
174 Node* _memory;
175 uint _alias_idx;
176
177 public:
178 C2AtomicParseAccess(GraphKit* kit, DecoratorSet decorators, BasicType type,
179 Node* base, C2AccessValuePtr& addr, uint alias_idx) :
180 C2ParseAccess(kit, decorators, type, base, addr),
181 _memory(nullptr),
182 _alias_idx(alias_idx) {}
183
184 // Set the memory node based on the current memory slice.
185 virtual void set_memory();
186
187 Node* memory() const { return _memory; }
188 uint alias_idx() const { return _alias_idx; }
189 };
190
191 // C2Access for optimization time calls to the BarrierSetC2 backend.
192 class C2OptAccess: public C2Access {
193 PhaseGVN& _gvn;
194 MergeMemNode* _mem;
195 Node* _ctl;
196
197 public:
198 C2OptAccess(PhaseGVN& gvn, Node* ctl, MergeMemNode* mem, DecoratorSet decorators,
199 BasicType type, Node* base, C2AccessValuePtr& addr) :
200 C2Access(decorators, type, base, addr),
201 _gvn(gvn), _mem(mem), _ctl(ctl) {
202 fixup_decorators();
203 }
204
205 MergeMemNode* mem() const { return _mem; }
206 Node* ctl() const { return _ctl; }
207
208 virtual PhaseGVN& gvn() const { return _gvn; }
209 virtual bool is_opt_access() const { return true; }
210 };
211
212 class BarrierSetC2State : public ArenaObj {
213 protected:
214 Node_Array _live;
215
216 public:
217 BarrierSetC2State(Arena* arena) : _live(arena) {}
218
219 RegMask* live(const Node* node) {
220 if (!node->is_Mach() || !needs_liveness_data(node->as_Mach())) {
221 // Don't need liveness for non-MachNodes or if the GC doesn't request it
222 return nullptr;
223 }
224 RegMask* live = (RegMask*)_live[node->_idx];
225 if (live == nullptr) {
226 live = new (Compile::current()->comp_arena()->AmallocWords(sizeof(RegMask))) RegMask();
227 _live.map(node->_idx, (Node*)live);
228 }
229
230 return live;
231 }
232
233 virtual bool needs_liveness_data(const MachNode* mach) const = 0;
234 virtual bool needs_livein_data() const = 0;
235 };
236
237 // This class represents the slow path in a C2 barrier. It is defined by a
238 // memory access, an entry point, and a continuation point (typically the end of
239 // the barrier). It provides a set of registers whose value is live across the
240 // barrier, and hence must be preserved across runtime calls from the stub.
241 class BarrierStubC2 : public ArenaObj {
242 protected:
243 const MachNode* _node;
244 Label _entry;
245 Label _continuation;
246 RegMask _preserve;
247
248 // Registers that are live-in/live-out of the entire memory access
249 // implementation (possibly including multiple barriers). Whether live-in or
250 // live-out registers are returned depends on
251 // BarrierSetC2State::needs_livein_data().
252 RegMask& live() const;
253
254 public:
255 BarrierStubC2(const MachNode* node);
256
257 // Entry point to the stub.
258 Label* entry();
259 // Return point from the stub (typically end of barrier).
260 Label* continuation();
261 // High-level, GC-specific barrier flags.
262 uint8_t barrier_data() const;
263
264 // Preserve the value in reg across runtime calls in this barrier.
265 void preserve(Register reg);
266 // Do not preserve the value in reg across runtime calls in this barrier.
267 void dont_preserve(Register reg);
268 // Set of registers whose value needs to be preserved across runtime calls in this barrier.
269 const RegMask& preserve_set() const;
270 };
271
272 // This is the top-level class for the backend of the Access API in C2.
273 // The top-level class is responsible for performing raw accesses. The
274 // various GC barrier sets inherit from the BarrierSetC2 class to sprinkle
275 // barriers into the accesses.
276 class BarrierSetC2: public CHeapObj<mtGC> {
277 protected:
278 virtual void resolve_address(C2Access& access) const;
279 virtual Node* store_at_resolved(C2Access& access, C2AccessValue& val) const;
280 virtual Node* load_at_resolved(C2Access& access, const Type* val_type) const;
281
282 virtual Node* atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
283 Node* new_val, const Type* val_type) const;
284 virtual Node* atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
285 Node* new_val, const Type* value_type) const;
286 virtual Node* atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const;
287 virtual Node* atomic_add_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const;
288 void pin_atomic_op(C2AtomicParseAccess& access) const;
289 void clone_in_runtime(PhaseMacroExpand* phase, ArrayCopyNode* ac,
290 address call_addr, const char* call_name) const;
291
292 public:
293 // This is the entry-point for the backend to perform accesses through the Access API.
294 virtual Node* store_at(C2Access& access, C2AccessValue& val) const;
295 virtual Node* load_at(C2Access& access, const Type* val_type) const;
296
297 virtual Node* atomic_cmpxchg_val_at(C2AtomicParseAccess& access, Node* expected_val,
298 Node* new_val, const Type* val_type) const;
299 virtual Node* atomic_cmpxchg_bool_at(C2AtomicParseAccess& access, Node* expected_val,
300 Node* new_val, const Type* val_type) const;
301 virtual Node* atomic_xchg_at(C2AtomicParseAccess& access, Node* new_val, const Type* value_type) const;
302 virtual Node* atomic_add_at(C2AtomicParseAccess& access, Node* new_val, const Type* value_type) const;
303
304 virtual void clone(GraphKit* kit, Node* src_base, Node* dst_base, Node* size, bool is_array) const;
305
306 virtual Node* obj_allocate(PhaseMacroExpand* macro, Node* mem, Node* toobig_false, Node* size_in_bytes,
307 Node*& i_o, Node*& needgc_ctrl,
308 Node*& fast_oop_ctrl, Node*& fast_oop_rawmem,
309 intx prefetch_lines) const;
310
311 virtual Node* ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const { return nullptr; }
312
313 // These are general helper methods used by C2
314 enum ArrayCopyPhase {
315 Parsing,
316 Optimization,
317 Expansion
318 };
319
320 virtual bool array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, bool is_clone_instance, ArrayCopyPhase phase) const { return false; }
321 virtual void clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const;
322
323 // Support for GC barriers emitted during parsing
324 virtual bool has_load_barrier_nodes() const { return false; }
325 virtual bool is_gc_pre_barrier_node(Node* node) const { return false; }
326 virtual bool is_gc_barrier_node(Node* node) const { return false; }
327 virtual Node* step_over_gc_barrier(Node* c) const { return c; }
328
329 // Support for macro expanded GC barriers
330 virtual void register_potential_barrier_node(Node* node) const { }
331 virtual void unregister_potential_barrier_node(Node* node) const { }
332 virtual void eliminate_gc_barrier(PhaseIterGVN* igvn, Node* node) const { }
333 virtual void eliminate_gc_barrier_data(Node* node) const { }
334 virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {}
335 virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {}
336
337 // Allow barrier sets to have shared state that is preserved across a compilation unit.
338 // This could for example comprise macro nodes to be expanded during macro expansion.
339 virtual void* create_barrier_state(Arena* comp_arena) const { return nullptr; }
340 // If the BarrierSetC2 state has barrier nodes in its compilation
341 // unit state to be expanded later, then now is the time to do so.
342 virtual bool expand_barriers(Compile* C, PhaseIterGVN& igvn) const { return false; }
343 virtual bool optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const { return false; }
344 virtual bool strip_mined_loops_expanded(LoopOptsMode mode) const { return false; }
345 virtual bool is_gc_specific_loop_opts_pass(LoopOptsMode mode) const { return false; }
346 // Estimated size of the node barrier in number of C2 Ideal nodes.
347 // This is used to guide heuristics in C2, e.g. whether to unroll a loop.
348 virtual uint estimated_barrier_size(const Node* node) const { return 0; }
349 // Whether the given store can be used to initialize a newly allocated object.
350 virtual bool can_initialize_object(const StoreNode* store) const { return true; }
351
352 enum CompilePhase {
353 BeforeOptimize,
354 BeforeMacroExpand,
355 BeforeCodeGen
356 };
357
358 #ifdef ASSERT
359 virtual void verify_gc_barriers(Compile* compile, CompilePhase phase) const {}
360 #endif
361
362 virtual bool final_graph_reshaping(Compile* compile, Node* n, uint opcode, Unique_Node_List& dead_nodes) const { return false; }
363
364 virtual bool escape_add_to_con_graph(ConnectionGraph* conn_graph, PhaseGVN* gvn, Unique_Node_List* delayed_worklist, Node* n, uint opcode) const { return false; }
365 virtual bool escape_add_final_edges(ConnectionGraph* conn_graph, PhaseGVN* gvn, Node* n, uint opcode) const { return false; }
366 virtual bool escape_has_out_with_unsafe_object(Node* n) const { return false; }
367
368 virtual bool matcher_find_shared_post_visit(Matcher* matcher, Node* n, uint opcode) const { return false; };
369 virtual bool matcher_is_store_load_barrier(Node* x, uint xop) const { return false; }
370
371 virtual void late_barrier_analysis() const { }
372 virtual void compute_liveness_at_stubs() const;
373 virtual int estimate_stub_size() const { return 0; }
374 virtual void emit_stubs(CodeBuffer& cb) const { }
375
376 static int arraycopy_payload_base_offset(bool is_array);
377
378 #ifndef PRODUCT
379 virtual void dump_barrier_data(const MachNode* mach, outputStream* st) const {
380 st->print("%x", mach->barrier_data());
381 };
382 #endif
383 };
384
385 #endif // SHARE_GC_SHARED_C2_BARRIERSETC2_HPP