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src/hotspot/share/oops/accessDecorators.hpp

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174 // * IN_NATIVE: The access is performed in an off-heap data structure.
175 const DecoratorSet IN_HEAP            = UCONST64(1) << 18;
176 const DecoratorSet IN_NATIVE          = UCONST64(1) << 19;
177 const DecoratorSet IN_DECORATOR_MASK  = IN_HEAP | IN_NATIVE;
178 
179 // == Boolean Flag Decorators ==
180 // * IS_ARRAY: The access is performed on a heap allocated array. This is sometimes a special case
181 //   for some GCs.
182 // * IS_DEST_UNINITIALIZED: This property can be important to e.g. SATB barriers by
183 //   marking that the previous value is uninitialized nonsense rather than a real value.
184 // * IS_NOT_NULL: This property can make certain barriers faster such as compressing oops.
185 const DecoratorSet IS_ARRAY              = UCONST64(1) << 20;
186 const DecoratorSet IS_DEST_UNINITIALIZED = UCONST64(1) << 21;
187 const DecoratorSet IS_NOT_NULL           = UCONST64(1) << 22;
188 
189 // == Arraycopy Decorators ==
190 // * ARRAYCOPY_CHECKCAST: This property means that the class of the objects in source
191 //   are not guaranteed to be subclasses of the class of the destination array. This requires
192 //   a check-cast barrier during the copying operation. If this is not set, it is assumed
193 //   that the array is covariant: (the source array type is-a destination array type)


194 // * ARRAYCOPY_DISJOINT: This property means that it is known that the two array ranges
195 //   are disjoint.
196 // * ARRAYCOPY_ARRAYOF: The copy is in the arrayof form.
197 // * ARRAYCOPY_ATOMIC: The accesses have to be atomic over the size of its elements.
198 // * ARRAYCOPY_ALIGNED: The accesses have to be aligned on a HeapWord.
199 const DecoratorSet ARRAYCOPY_CHECKCAST            = UCONST64(1) << 23;
200 const DecoratorSet ARRAYCOPY_DISJOINT             = UCONST64(1) << 24;
201 const DecoratorSet ARRAYCOPY_ARRAYOF              = UCONST64(1) << 25;
202 const DecoratorSet ARRAYCOPY_ATOMIC               = UCONST64(1) << 26;
203 const DecoratorSet ARRAYCOPY_ALIGNED              = UCONST64(1) << 27;
204 const DecoratorSet ARRAYCOPY_DECORATOR_MASK       = ARRAYCOPY_CHECKCAST | ARRAYCOPY_DISJOINT |

205                                                     ARRAYCOPY_DISJOINT | ARRAYCOPY_ARRAYOF |
206                                                     ARRAYCOPY_ATOMIC | ARRAYCOPY_ALIGNED;
207 
208 // == Resolve barrier decorators ==
209 // * ACCESS_READ: Indicate that the resolved object is accessed read-only. This allows the GC
210 //   backend to use weaker and more efficient barriers.
211 // * ACCESS_WRITE: Indicate that the resolved object is used for write access.
212 const DecoratorSet ACCESS_READ                    = UCONST64(1) << 28;
213 const DecoratorSet ACCESS_WRITE                   = UCONST64(1) << 29;
214 
215 // Keep track of the last decorator.
216 const DecoratorSet DECORATOR_LAST = UCONST64(1) << 29;
217 
218 namespace AccessInternal {
219   // This class adds implied decorators that follow according to decorator rules.
220   // For example adding default reference strength and default memory ordering
221   // semantics.
222   template <DecoratorSet input_decorators>
223   struct DecoratorFixup: AllStatic {
224     // If no reference strength has been picked, then strong will be picked
225     static const DecoratorSet ref_strength_default = input_decorators |
226       (((ON_DECORATOR_MASK & input_decorators) == 0 && (INTERNAL_VALUE_IS_OOP & input_decorators) != 0) ?
227        ON_STRONG_OOP_REF : DECORATORS_NONE);
228     // If no memory ordering has been picked, unordered will be picked
229     static const DecoratorSet memory_ordering_default = ref_strength_default |
230       ((MO_DECORATOR_MASK & ref_strength_default) == 0 ? MO_UNORDERED : DECORATORS_NONE);
231     // If no barrier strength has been picked, normal will be used
232     static const DecoratorSet barrier_strength_default = memory_ordering_default |
233       ((AS_DECORATOR_MASK & memory_ordering_default) == 0 ? AS_NORMAL : DECORATORS_NONE);
234     static const DecoratorSet value = barrier_strength_default;
235   };
236 

174 // * IN_NATIVE: The access is performed in an off-heap data structure.
175 const DecoratorSet IN_HEAP            = UCONST64(1) << 18;
176 const DecoratorSet IN_NATIVE          = UCONST64(1) << 19;
177 const DecoratorSet IN_DECORATOR_MASK  = IN_HEAP | IN_NATIVE;
178 
179 // == Boolean Flag Decorators ==
180 // * IS_ARRAY: The access is performed on a heap allocated array. This is sometimes a special case
181 //   for some GCs.
182 // * IS_DEST_UNINITIALIZED: This property can be important to e.g. SATB barriers by
183 //   marking that the previous value is uninitialized nonsense rather than a real value.
184 // * IS_NOT_NULL: This property can make certain barriers faster such as compressing oops.
185 const DecoratorSet IS_ARRAY              = UCONST64(1) << 20;
186 const DecoratorSet IS_DEST_UNINITIALIZED = UCONST64(1) << 21;
187 const DecoratorSet IS_NOT_NULL           = UCONST64(1) << 22;
188 
189 // == Arraycopy Decorators ==
190 // * ARRAYCOPY_CHECKCAST: This property means that the class of the objects in source
191 //   are not guaranteed to be subclasses of the class of the destination array. This requires
192 //   a check-cast barrier during the copying operation. If this is not set, it is assumed
193 //   that the array is covariant: (the source array type is-a destination array type)
194 // * ARRAYCOPY_NOTNULL: This property means that the source array may contain null elements
195 //   but the destination does not allow null elements (i.e. throw NPE)
196 // * ARRAYCOPY_DISJOINT: This property means that it is known that the two array ranges
197 //   are disjoint.
198 // * ARRAYCOPY_ARRAYOF: The copy is in the arrayof form.
199 // * ARRAYCOPY_ATOMIC: The accesses have to be atomic over the size of its elements.
200 // * ARRAYCOPY_ALIGNED: The accesses have to be aligned on a HeapWord.
201 const DecoratorSet ARRAYCOPY_CHECKCAST            = UCONST64(1) << 23;
202 const DecoratorSet ARRAYCOPY_NOTNULL              = UCONST64(1) << 24;
203 const DecoratorSet ARRAYCOPY_DISJOINT             = UCONST64(1) << 25;
204 const DecoratorSet ARRAYCOPY_ARRAYOF              = UCONST64(1) << 26;
205 const DecoratorSet ARRAYCOPY_ATOMIC               = UCONST64(1) << 27;
206 const DecoratorSet ARRAYCOPY_ALIGNED              = UCONST64(1) << 28;
207 const DecoratorSet ARRAYCOPY_DECORATOR_MASK       = ARRAYCOPY_CHECKCAST | ARRAYCOPY_NOTNULL |
208                                                     ARRAYCOPY_DISJOINT | ARRAYCOPY_ARRAYOF |
209                                                     ARRAYCOPY_ATOMIC | ARRAYCOPY_ALIGNED;
210 
211 // == Resolve barrier decorators ==
212 // * ACCESS_READ: Indicate that the resolved object is accessed read-only. This allows the GC
213 //   backend to use weaker and more efficient barriers.
214 // * ACCESS_WRITE: Indicate that the resolved object is used for write access.
215 const DecoratorSet ACCESS_READ                    = UCONST64(1) << 29;
216 const DecoratorSet ACCESS_WRITE                   = UCONST64(1) << 30;
217 
218 // Keep track of the last decorator.
219 const DecoratorSet DECORATOR_LAST = UCONST64(1) << 30;
220 
221 namespace AccessInternal {
222   // This class adds implied decorators that follow according to decorator rules.
223   // For example adding default reference strength and default memory ordering
224   // semantics.
225   template <DecoratorSet input_decorators>
226   struct DecoratorFixup: AllStatic {
227     // If no reference strength has been picked, then strong will be picked
228     static const DecoratorSet ref_strength_default = input_decorators |
229       (((ON_DECORATOR_MASK & input_decorators) == 0 && (INTERNAL_VALUE_IS_OOP & input_decorators) != 0) ?
230        ON_STRONG_OOP_REF : DECORATORS_NONE);
231     // If no memory ordering has been picked, unordered will be picked
232     static const DecoratorSet memory_ordering_default = ref_strength_default |
233       ((MO_DECORATOR_MASK & ref_strength_default) == 0 ? MO_UNORDERED : DECORATORS_NONE);
234     // If no barrier strength has been picked, normal will be used
235     static const DecoratorSet barrier_strength_default = memory_ordering_default |
236       ((AS_DECORATOR_MASK & memory_ordering_default) == 0 ? AS_NORMAL : DECORATORS_NONE);
237     static const DecoratorSet value = barrier_strength_default;
238   };
239 
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