1 /*
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 24 
 25 #ifndef SHARE_OOPS_ACCESS_HPP
 26 #define SHARE_OOPS_ACCESS_HPP
 27 
 28 #include "memory/allocation.hpp"
 29 #include "oops/accessBackend.hpp"
 30 #include "oops/accessDecorators.hpp"
 31 #include "oops/oopsHierarchy.hpp"
 32 #include "utilities/debug.hpp"
 33 #include "utilities/globalDefinitions.hpp"
 34 
 35 
 36 // = GENERAL =
 37 // Access is an API for performing accesses with declarative semantics. Each access can have a number of "decorators".
 38 // A decorator is an attribute or property that affects the way a memory access is performed in some way.
 39 // There are different groups of decorators. Some have to do with memory ordering, others to do with,
 40 // e.g. strength of references, strength of GC barriers, or whether compression should be applied or not.
 41 // Some decorators are set at buildtime, such as whether primitives require GC barriers or not, others
 42 // at callsites such as whether an access is in the heap or not, and others are resolved at runtime
 43 // such as GC-specific barriers and encoding/decoding compressed oops. For more information about what
 44 // decorators are available, cf. oops/accessDecorators.hpp.
 45 // By pipelining handling of these decorators, the design of the Access API allows separation of concern
 46 // over the different orthogonal concerns of decorators, while providing a powerful way of
 47 // expressing these orthogonal semantic properties in a unified way.
 48 //
 49 // == OPERATIONS ==
 50 // * load: Load a value from an address.
 51 // * load_at: Load a value from an internal pointer relative to a base object.
 52 // * store: Store a value at an address.
 53 // * store_at: Store a value in an internal pointer relative to a base object.
 54 // * atomic_cmpxchg: Atomically compare-and-swap a new value at an address if previous value matched the compared value.
 55 // * atomic_cmpxchg_at: Atomically compare-and-swap a new value at an internal pointer address if previous value matched the compared value.
 56 // * atomic_xchg: Atomically swap a new value at an address if previous value matched the compared value.
 57 // * atomic_xchg_at: Atomically swap a new value at an internal pointer address if previous value matched the compared value.
 58 // * arraycopy: Copy data from one heap array to another heap array. The ArrayAccess class has convenience functions for this.
 59 // * clone: Clone the contents of an object to a newly allocated object.
 60 // * value_copy: Copy the contents of a value type from one heap address to another
 61 //
 62 // == IMPLEMENTATION ==
 63 // Each access goes through the following steps in a template pipeline.
 64 // There are essentially 5 steps for each access:
 65 // * Step 1:   Set default decorators and decay types. This step gets rid of CV qualifiers
 66 //             and sets default decorators to sensible values.
 67 // * Step 2:   Reduce types. This step makes sure there is only a single T type and not
 68 //             multiple types. The P type of the address and T type of the value must
 69 //             match.
 70 // * Step 3:   Pre-runtime dispatch. This step checks whether a runtime call can be
 71 //             avoided, and in that case avoids it (calling raw accesses or
 72 //             primitive accesses in a build that does not require primitive GC barriers)
 73 // * Step 4:   Runtime-dispatch. This step performs a runtime dispatch to the corresponding
 74 //             BarrierSet::AccessBarrier accessor that attaches GC-required barriers
 75 //             to the access.
 76 // * Step 5.a: Barrier resolution. This step is invoked the first time a runtime-dispatch
 77 //             happens for an access. The appropriate BarrierSet::AccessBarrier accessor
 78 //             is resolved, then the function pointer is updated to that accessor for
 79 //             future invocations.
 80 // * Step 5.b: Post-runtime dispatch. This step now casts previously unknown types such
 81 //             as the address type of an oop on the heap (is it oop* or narrowOop*) to
 82 //             the appropriate type. It also splits sufficiently orthogonal accesses into
 83 //             different functions, such as whether the access involves oops or primitives
 84 //             and whether the access is performed on the heap or outside. Then the
 85 //             appropriate BarrierSet::AccessBarrier is called to perform the access.
 86 //
 87 // The implementation of step 1-4 resides in in accessBackend.hpp, to allow selected
 88 // accesses to be accessible from only access.hpp, as opposed to access.inline.hpp.
 89 // Steps 5.a and 5.b require knowledge about the GC backends, and therefore needs to
 90 // include the various GC backend .inline.hpp headers. Their implementation resides in
 91 // access.inline.hpp. The accesses that are allowed through the access.hpp file
 92 // must be instantiated in access.cpp using the INSTANTIATE_HPP_ACCESS macro.
 93 
 94 class InlineKlass;
 95 
 96 template <DecoratorSet decorators = DECORATORS_NONE>
 97 class Access: public AllStatic {
 98   // This function asserts that if an access gets passed in a decorator outside
 99   // of the expected_decorators, then something is wrong. It additionally checks
100   // the consistency of the decorators so that supposedly disjoint decorators are indeed
101   // disjoint. For example, an access can not be both in heap and on root at the
102   // same time.
103   template <DecoratorSet expected_decorators>
104   static void verify_decorators();
105 
106   template <DecoratorSet expected_mo_decorators>
107   static void verify_primitive_decorators() {
108     const DecoratorSet primitive_decorators = (AS_DECORATOR_MASK ^ AS_NO_KEEPALIVE) |
109                                               IN_HEAP | IS_ARRAY;
110     verify_decorators<expected_mo_decorators | primitive_decorators>();
111   }
112 
113   template <DecoratorSet expected_mo_decorators>
114   static void verify_oop_decorators() {
115     const DecoratorSet oop_decorators = AS_DECORATOR_MASK | IN_DECORATOR_MASK |
116                                         (ON_DECORATOR_MASK ^ ON_UNKNOWN_OOP_REF) | // no unknown oop refs outside of the heap
117                                         IS_ARRAY | IS_NOT_NULL | IS_DEST_UNINITIALIZED;
118     verify_decorators<expected_mo_decorators | oop_decorators>();
119   }
120 
121   template <DecoratorSet expected_mo_decorators>
122   static void verify_heap_oop_decorators() {
123     const DecoratorSet heap_oop_decorators = AS_DECORATOR_MASK | ON_DECORATOR_MASK |
124                                              IN_HEAP | IS_ARRAY | IS_NOT_NULL;
125     verify_decorators<expected_mo_decorators | heap_oop_decorators>();
126   }
127 
128   template <DecoratorSet expected_mo_decorators>
129   static void verify_heap_value_decorators() {
130     const DecoratorSet heap_value_decorators = IN_HEAP | IS_DEST_UNINITIALIZED;
131     verify_decorators<expected_mo_decorators | heap_value_decorators>();
132   }
133 
134   static const DecoratorSet load_mo_decorators = MO_UNORDERED | MO_RELAXED | MO_ACQUIRE | MO_SEQ_CST;
135   static const DecoratorSet store_mo_decorators = MO_UNORDERED | MO_RELAXED | MO_RELEASE | MO_SEQ_CST;
136   static const DecoratorSet atomic_xchg_mo_decorators = MO_SEQ_CST;
137   static const DecoratorSet atomic_cmpxchg_mo_decorators = MO_RELAXED | MO_SEQ_CST;
138 
139 protected:
140   template <typename T>
141   static inline void oop_arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, const T* src_raw,
142                                    arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
143                                    size_t length) {
144     verify_decorators<ARRAYCOPY_DECORATOR_MASK | IN_HEAP |
145                       AS_DECORATOR_MASK | IS_ARRAY | IS_DEST_UNINITIALIZED>();
146     AccessInternal::arraycopy<decorators | INTERNAL_VALUE_IS_OOP>(src_obj, src_offset_in_bytes, src_raw,
147                                                                   dst_obj, dst_offset_in_bytes, dst_raw,
148                                                                   length);
149   }
150 
151   template <typename T>
152   static inline void arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, const T* src_raw,
153                                arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
154                                size_t length) {
155     verify_decorators<ARRAYCOPY_DECORATOR_MASK | IN_HEAP |
156                       AS_DECORATOR_MASK | IS_ARRAY>();
157     AccessInternal::arraycopy<decorators>(src_obj, src_offset_in_bytes, src_raw,
158                                           dst_obj, dst_offset_in_bytes, dst_raw,
159                                           length);
160   }
161 
162 public:
163   // Primitive heap accesses
164   static inline AccessInternal::LoadAtProxy<decorators> load_at(oop base, ptrdiff_t offset) {
165     verify_primitive_decorators<load_mo_decorators>();
166     return AccessInternal::LoadAtProxy<decorators>(base, offset);
167   }
168 
169   template <typename T>
170   static inline void store_at(oop base, ptrdiff_t offset, T value) {
171     verify_primitive_decorators<store_mo_decorators>();
172     AccessInternal::store_at<decorators>(base, offset, value);
173   }
174 
175   template <typename T>
176   static inline T atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
177     verify_primitive_decorators<atomic_cmpxchg_mo_decorators>();
178     return AccessInternal::atomic_cmpxchg_at<decorators>(base, offset, compare_value, new_value);
179   }
180 
181   template <typename T>
182   static inline T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
183     verify_primitive_decorators<atomic_xchg_mo_decorators>();
184     return AccessInternal::atomic_xchg_at<decorators>(base, offset, new_value);
185   }
186 
187   // Oop heap accesses
188   static inline AccessInternal::OopLoadAtProxy<decorators> oop_load_at(oop base, ptrdiff_t offset) {
189     verify_heap_oop_decorators<load_mo_decorators>();
190     return AccessInternal::OopLoadAtProxy<decorators>(base, offset);
191   }
192 
193   template <typename T>
194   static inline void oop_store_at(oop base, ptrdiff_t offset, T value) {
195     verify_heap_oop_decorators<store_mo_decorators>();
196     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
197     OopType oop_value = value;
198     AccessInternal::store_at<decorators | INTERNAL_VALUE_IS_OOP>(base, offset, oop_value);
199   }
200 
201   template <typename T>
202   static inline T oop_atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
203     verify_heap_oop_decorators<atomic_cmpxchg_mo_decorators>();
204     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
205     OopType new_oop_value = new_value;
206     OopType compare_oop_value = compare_value;
207     return AccessInternal::atomic_cmpxchg_at<decorators | INTERNAL_VALUE_IS_OOP>(base, offset, compare_oop_value, new_oop_value);
208   }
209 
210   template <typename T>
211   static inline T oop_atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
212     verify_heap_oop_decorators<atomic_xchg_mo_decorators>();
213     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
214     OopType new_oop_value = new_value;
215     return AccessInternal::atomic_xchg_at<decorators | INTERNAL_VALUE_IS_OOP>(base, offset, new_oop_value);
216   }
217 
218   // Clone an object from src to dst
219   static inline void clone(oop src, oop dst, size_t size) {
220     verify_decorators<IN_HEAP>();
221     AccessInternal::clone<decorators>(src, dst, size);
222   }
223 
224   // inline type heap access (when inlined)...
225 
226   // Copy value type data from src to dst
227   static inline void value_copy(void* src, void* dst, InlineKlass* md) {
228     verify_heap_value_decorators<IN_HEAP>();
229     AccessInternal::value_copy<decorators>(src, dst, md);
230   }
231 
232   // Primitive accesses
233   template <typename P>
234   static inline P load(P* addr) {
235     verify_primitive_decorators<load_mo_decorators>();
236     return AccessInternal::load<decorators, P, P>(addr);
237   }
238 
239   template <typename P, typename T>
240   static inline void store(P* addr, T value) {
241     verify_primitive_decorators<store_mo_decorators>();
242     AccessInternal::store<decorators>(addr, value);
243   }
244 
245   template <typename P, typename T>
246   static inline T atomic_cmpxchg(P* addr, T compare_value, T new_value) {
247     verify_primitive_decorators<atomic_cmpxchg_mo_decorators>();
248     return AccessInternal::atomic_cmpxchg<decorators>(addr, compare_value, new_value);
249   }
250 
251   template <typename P, typename T>
252   static inline T atomic_xchg(P* addr, T new_value) {
253     verify_primitive_decorators<atomic_xchg_mo_decorators>();
254     return AccessInternal::atomic_xchg<decorators>(addr, new_value);
255   }
256 
257   // Oop accesses
258   template <typename P>
259   static inline AccessInternal::OopLoadProxy<P, decorators> oop_load(P* addr) {
260     verify_oop_decorators<load_mo_decorators>();
261     return AccessInternal::OopLoadProxy<P, decorators>(addr);
262   }
263 
264   template <typename P, typename T>
265   static inline void oop_store(P* addr, T value) {
266     verify_oop_decorators<store_mo_decorators>();
267     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
268     OopType oop_value = value;
269     AccessInternal::store<decorators | INTERNAL_VALUE_IS_OOP>(addr, oop_value);
270   }
271 
272   template <typename P, typename T>
273   static inline T oop_atomic_cmpxchg(P* addr, T compare_value, T new_value) {
274     verify_oop_decorators<atomic_cmpxchg_mo_decorators>();
275     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
276     OopType new_oop_value = new_value;
277     OopType compare_oop_value = compare_value;
278     return AccessInternal::atomic_cmpxchg<decorators | INTERNAL_VALUE_IS_OOP>(addr, compare_oop_value, new_oop_value);
279   }
280 
281   template <typename P, typename T>
282   static inline T oop_atomic_xchg(P* addr, T new_value) {
283     verify_oop_decorators<atomic_xchg_mo_decorators>();
284     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
285     OopType new_oop_value = new_value;
286     return AccessInternal::atomic_xchg<decorators | INTERNAL_VALUE_IS_OOP>(addr, new_oop_value);
287   }
288 };
289 
290 // Helper for performing raw accesses (knows only of memory ordering
291 // atomicity decorators as well as compressed oops)
292 template <DecoratorSet decorators = DECORATORS_NONE>
293 class RawAccess: public Access<AS_RAW | decorators> {};
294 
295 // Helper for performing normal accesses on the heap. These accesses
296 // may resolve an accessor on a GC barrier set
297 template <DecoratorSet decorators = DECORATORS_NONE>
298 class HeapAccess: public Access<IN_HEAP | decorators> {};
299 
300 // Helper for performing normal accesses in roots. These accesses
301 // may resolve an accessor on a GC barrier set
302 template <DecoratorSet decorators = DECORATORS_NONE>
303 class NativeAccess: public Access<IN_NATIVE | decorators> {};
304 
305 // Helper for array access.
306 template <DecoratorSet decorators = DECORATORS_NONE>
307 class ArrayAccess: public HeapAccess<IS_ARRAY | decorators> {
308   typedef HeapAccess<IS_ARRAY | decorators> AccessT;
309 public:
310   template <typename T>
311   static inline void arraycopy(arrayOop src_obj, size_t src_offset_in_bytes,
312                                arrayOop dst_obj, size_t dst_offset_in_bytes,
313                                size_t length) {
314     AccessT::arraycopy(src_obj, src_offset_in_bytes, reinterpret_cast<const T*>(NULL),
315                        dst_obj, dst_offset_in_bytes, reinterpret_cast<T*>(NULL),
316                        length);
317   }
318 
319   template <typename T>
320   static inline void arraycopy_to_native(arrayOop src_obj, size_t src_offset_in_bytes,
321                                          T* dst,
322                                          size_t length) {
323     AccessT::arraycopy(src_obj, src_offset_in_bytes, reinterpret_cast<const T*>(NULL),
324                        NULL, 0, dst,
325                        length);
326   }
327 
328   template <typename T>
329   static inline void arraycopy_from_native(const T* src,
330                                            arrayOop dst_obj, size_t dst_offset_in_bytes,
331                                            size_t length) {
332     AccessT::arraycopy(NULL, 0, src,
333                        dst_obj, dst_offset_in_bytes, reinterpret_cast<T*>(NULL),
334                        length);
335   }
336 
337   static inline void oop_arraycopy(arrayOop src_obj, size_t src_offset_in_bytes,
338                                    arrayOop dst_obj, size_t dst_offset_in_bytes,
339                                    size_t length) {
340     AccessT::oop_arraycopy(src_obj, src_offset_in_bytes, reinterpret_cast<const HeapWord*>(NULL),
341                            dst_obj, dst_offset_in_bytes, reinterpret_cast<HeapWord*>(NULL),
342                            length);
343   }
344 
345   template <typename T>
346   static inline void oop_arraycopy_raw(T* src, T* dst, size_t length) {
347     AccessT::oop_arraycopy(NULL, 0, src,
348                            NULL, 0, dst,
349                            length);
350   }
351 
352 };
353 
354 template <DecoratorSet decorators>
355 template <DecoratorSet expected_decorators>
356 void Access<decorators>::verify_decorators() {
357   STATIC_ASSERT((~expected_decorators & decorators) == 0); // unexpected decorator used
358   const DecoratorSet barrier_strength_decorators = decorators & AS_DECORATOR_MASK;
359   STATIC_ASSERT(barrier_strength_decorators == 0 || ( // make sure barrier strength decorators are disjoint if set
360     (barrier_strength_decorators ^ AS_NO_KEEPALIVE) == 0 ||
361     (barrier_strength_decorators ^ AS_RAW) == 0 ||
362     (barrier_strength_decorators ^ AS_NORMAL) == 0
363   ));
364   const DecoratorSet ref_strength_decorators = decorators & ON_DECORATOR_MASK;
365   STATIC_ASSERT(ref_strength_decorators == 0 || ( // make sure ref strength decorators are disjoint if set
366     (ref_strength_decorators ^ ON_STRONG_OOP_REF) == 0 ||
367     (ref_strength_decorators ^ ON_WEAK_OOP_REF) == 0 ||
368     (ref_strength_decorators ^ ON_PHANTOM_OOP_REF) == 0 ||
369     (ref_strength_decorators ^ ON_UNKNOWN_OOP_REF) == 0
370   ));
371   const DecoratorSet memory_ordering_decorators = decorators & MO_DECORATOR_MASK;
372   STATIC_ASSERT(memory_ordering_decorators == 0 || ( // make sure memory ordering decorators are disjoint if set
373     (memory_ordering_decorators ^ MO_UNORDERED) == 0 ||
374     (memory_ordering_decorators ^ MO_RELAXED) == 0 ||
375     (memory_ordering_decorators ^ MO_ACQUIRE) == 0 ||
376     (memory_ordering_decorators ^ MO_RELEASE) == 0 ||
377     (memory_ordering_decorators ^ MO_SEQ_CST) == 0
378   ));
379   const DecoratorSet location_decorators = decorators & IN_DECORATOR_MASK;
380   STATIC_ASSERT(location_decorators == 0 || ( // make sure location decorators are disjoint if set
381     (location_decorators ^ IN_NATIVE) == 0 ||
382     (location_decorators ^ IN_HEAP) == 0
383   ));
384 }
385 
386 #endif // SHARE_OOPS_ACCESS_HPP
--- EOF ---