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 *
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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
151 void* barrier_set_state() const;
152
153 public:
154 C2ParseAccess(GraphKit* kit, DecoratorSet decorators,
155 BasicType type, Node* base, C2AccessValuePtr& addr) :
156 C2Access(decorators, type, base, addr),
157 _kit(kit) {
158 fixup_decorators();
159 }
160
161 GraphKit* kit() const { return _kit; }
162
163 virtual PhaseGVN& gvn() const;
164 virtual bool is_parse_access() const { return true; }
165 };
166
167 // This class wraps a bunch of context parameters that are passed around in the
168 // BarrierSetC2 backend hierarchy, for atomic accesses, to reduce boiler plate.
169 class C2AtomicParseAccess: public C2ParseAccess {
170 Node* _memory;
171 uint _alias_idx;
172
173 public:
174 C2AtomicParseAccess(GraphKit* kit, DecoratorSet decorators, BasicType type,
175 Node* base, C2AccessValuePtr& addr, uint alias_idx) :
176 C2ParseAccess(kit, decorators, type, base, addr),
177 _memory(nullptr),
178 _alias_idx(alias_idx) {}
179
180 // Set the memory node based on the current memory slice.
181 virtual void set_memory();
182
183 Node* memory() const { return _memory; }
184 uint alias_idx() const { return _alias_idx; }
185 };
186
187 // C2Access for optimization time calls to the BarrierSetC2 backend.
188 class C2OptAccess: public C2Access {
189 PhaseGVN& _gvn;
190 MergeMemNode* _mem;
191 Node* _ctl;
192
193 public:
194 C2OptAccess(PhaseGVN& gvn, Node* ctl, MergeMemNode* mem, DecoratorSet decorators,
195 BasicType type, Node* base, C2AccessValuePtr& addr) :
196 C2Access(decorators, type, base, addr),
197 _gvn(gvn), _mem(mem), _ctl(ctl) {
198 fixup_decorators();
199 }
200
201 MergeMemNode* mem() const { return _mem; }
202 Node* ctl() const { return _ctl; }
203
204 virtual PhaseGVN& gvn() const { return _gvn; }
205 virtual bool is_opt_access() const { return true; }
206 };
207
208 class BarrierSetC2State : public ArenaObj {
209 protected:
210 Node_Array _live;
211
212 public:
213 BarrierSetC2State(Arena* arena) : _live(arena) {}
214
215 RegMask* live(const Node* node) {
216 if (!node->is_Mach() || !needs_liveness_data(node->as_Mach())) {
217 // Don't need liveness for non-MachNodes or if the GC doesn't request it
218 return nullptr;
219 }
220 RegMask* live = (RegMask*)_live[node->_idx];
221 if (live == nullptr) {
222 live = new (Compile::current()->comp_arena()->AmallocWords(sizeof(RegMask))) RegMask();
223 _live.map(node->_idx, (Node*)live);
224 }
225
226 return live;
227 }
228
229 virtual bool needs_liveness_data(const MachNode* mach) const = 0;
230 virtual bool needs_livein_data() const = 0;
231 };
232
233 // This class represents the slow path in a C2 barrier. It is defined by a
234 // memory access, an entry point, and a continuation point (typically the end of
235 // the barrier). It provides a set of registers whose value is live across the
236 // barrier, and hence must be preserved across runtime calls from the stub.
237 class BarrierStubC2 : public ArenaObj {
238 protected:
239 const MachNode* _node;
240 Label _entry;
241 Label _continuation;
242 RegMask _preserve;
243
244 // Registers that are live-in/live-out of the entire memory access
245 // implementation (possibly including multiple barriers). Whether live-in or
246 // live-out registers are returned depends on
247 // BarrierSetC2State::needs_livein_data().
248 RegMask& live() const;
249
250 public:
251 BarrierStubC2(const MachNode* node);
252
253 // Entry point to the stub.
254 Label* entry();
255 // Return point from the stub (typically end of barrier).
256 Label* continuation();
257 // High-level, GC-specific barrier flags.
258 uint8_t barrier_data() const;
259
260 // Preserve the value in reg across runtime calls in this barrier.
261 void preserve(Register reg);
262 // Do not preserve the value in reg across runtime calls in this barrier.
263 void dont_preserve(Register reg);
264 // Set of registers whose value needs to be preserved across runtime calls in this barrier.
265 const RegMask& preserve_set() const;
266 };
267
268 // This is the top-level class for the backend of the Access API in C2.
269 // The top-level class is responsible for performing raw accesses. The
270 // various GC barrier sets inherit from the BarrierSetC2 class to sprinkle
271 // barriers into the accesses.
272 class BarrierSetC2: public CHeapObj<mtGC> {
273 protected:
274 virtual void resolve_address(C2Access& access) const;
275 virtual Node* store_at_resolved(C2Access& access, C2AccessValue& val) const;
276 virtual Node* load_at_resolved(C2Access& access, const Type* val_type) const;
277
278 virtual Node* atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
279 Node* new_val, const Type* val_type) const;
280 virtual Node* atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
281 Node* new_val, const Type* value_type) const;
282 virtual Node* atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const;
283 virtual Node* atomic_add_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const;
284 void pin_atomic_op(C2AtomicParseAccess& access) const;
285 void clone_in_runtime(PhaseMacroExpand* phase, ArrayCopyNode* ac,
286 address call_addr, const char* call_name) const;
287
288 public:
289 // This is the entry-point for the backend to perform accesses through the Access API.
290 virtual Node* store_at(C2Access& access, C2AccessValue& val) const;
291 virtual Node* load_at(C2Access& access, const Type* val_type) const;
292
293 virtual Node* atomic_cmpxchg_val_at(C2AtomicParseAccess& access, Node* expected_val,
294 Node* new_val, const Type* val_type) const;
295 virtual Node* atomic_cmpxchg_bool_at(C2AtomicParseAccess& access, Node* expected_val,
296 Node* new_val, const Type* val_type) const;
297 virtual Node* atomic_xchg_at(C2AtomicParseAccess& access, Node* new_val, const Type* value_type) const;
298 virtual Node* atomic_add_at(C2AtomicParseAccess& access, Node* new_val, const Type* value_type) const;
299
300 virtual void clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const;
301
302 virtual Node* obj_allocate(PhaseMacroExpand* macro, Node* mem, Node* toobig_false, Node* size_in_bytes,
303 Node*& i_o, Node*& needgc_ctrl,
304 Node*& fast_oop_ctrl, Node*& fast_oop_rawmem,
305 intx prefetch_lines) const;
306
307 virtual Node* ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const { return nullptr; }
308
309 // These are general helper methods used by C2
310 enum ArrayCopyPhase {
311 Parsing,
312 Optimization,
313 Expansion
314 };
315
316 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; }
317 virtual void clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const;
318
319 // Support for GC barriers emitted during parsing
320 virtual bool has_load_barrier_nodes() const { return false; }
321 virtual bool is_gc_pre_barrier_node(Node* node) const { return false; }
322 virtual bool is_gc_barrier_node(Node* node) const { return false; }
323 virtual Node* step_over_gc_barrier(Node* c) const { return c; }
324
325 // Support for macro expanded GC barriers
326 virtual void register_potential_barrier_node(Node* node) const { }
327 virtual void unregister_potential_barrier_node(Node* node) const { }
328 virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
329 virtual void eliminate_gc_barrier_data(Node* node) const { }
330 virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {}
331 virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {}
332
333 // Allow barrier sets to have shared state that is preserved across a compilation unit.
334 // This could for example comprise macro nodes to be expanded during macro expansion.
335 virtual void* create_barrier_state(Arena* comp_arena) const { return nullptr; }
336 // If the BarrierSetC2 state has barrier nodes in its compilation
337 // unit state to be expanded later, then now is the time to do so.
338 virtual bool expand_barriers(Compile* C, PhaseIterGVN& igvn) const { return false; }
339 virtual bool optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const { return false; }
340 virtual bool strip_mined_loops_expanded(LoopOptsMode mode) const { return false; }
341 virtual bool is_gc_specific_loop_opts_pass(LoopOptsMode mode) const { return false; }
342 // Estimated size of the node barrier in number of C2 Ideal nodes.
343 // This is used to guide heuristics in C2, e.g. whether to unroll a loop.
344 virtual uint estimated_barrier_size(const Node* node) const { return 0; }
345 // Whether the given store can be used to initialize a newly allocated object.
346 virtual bool can_initialize_object(const StoreNode* store) const { return true; }
347
348 enum CompilePhase {
349 BeforeOptimize,
350 BeforeMacroExpand,
351 BeforeCodeGen
352 };
353
354 #ifdef ASSERT
355 virtual void verify_gc_barriers(Compile* compile, CompilePhase phase) const {}
356 #endif
357
358 virtual bool final_graph_reshaping(Compile* compile, Node* n, uint opcode, Unique_Node_List& dead_nodes) const { return false; }
359
360 virtual bool escape_add_to_con_graph(ConnectionGraph* conn_graph, PhaseGVN* gvn, Unique_Node_List* delayed_worklist, Node* n, uint opcode) const { return false; }
361 virtual bool escape_add_final_edges(ConnectionGraph* conn_graph, PhaseGVN* gvn, Node* n, uint opcode) const { return false; }
362 virtual bool escape_has_out_with_unsafe_object(Node* n) const { return false; }
363
364 virtual bool matcher_find_shared_post_visit(Matcher* matcher, Node* n, uint opcode) const { return false; };
365 virtual bool matcher_is_store_load_barrier(Node* x, uint xop) const { return false; }
366
367 virtual void late_barrier_analysis() const { }
368 virtual void compute_liveness_at_stubs() const;
369 virtual int estimate_stub_size() const { return 0; }
370 virtual void emit_stubs(CodeBuffer& cb) const { }
371
372 static int arraycopy_payload_base_offset(bool is_array);
373
374 #ifndef PRODUCT
375 virtual void dump_barrier_data(const MachNode* mach, outputStream* st) const {
376 st->print("%x", mach->barrier_data());
377 };
378 #endif
379 };
380
381 #endif // SHARE_GC_SHARED_C2_BARRIERSETC2_HPP