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1 // Copyright 2013 the V8 project authors. All rights reserved. | 1 // Copyright 2013 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | 27 |
28 #ifndef V8_HYDROGEN_UNIQUE_H_ | 28 #ifndef V8_HYDROGEN_UNIQUE_H_ |
29 #define V8_HYDROGEN_UNIQUE_H_ | 29 #define V8_HYDROGEN_UNIQUE_H_ |
30 | 30 |
31 #include "handles.h" | 31 #include "handles.h" |
| 32 #include "objects.h" |
32 #include "utils.h" | 33 #include "utils.h" |
33 #include "zone.h" | 34 #include "zone.h" |
34 | 35 |
35 namespace v8 { | 36 namespace v8 { |
36 namespace internal { | 37 namespace internal { |
37 | 38 |
38 | 39 |
39 template <typename T> | 40 template <typename T> |
40 class UniqueSet; | 41 class UniqueSet; |
41 | 42 |
42 | 43 |
43 // Represents a handle to an object on the heap, but with the additional | 44 // Represents a handle to an object on the heap, but with the additional |
44 // ability of checking for equality and hashing without accessing the heap. | 45 // ability of checking for equality and hashing without accessing the heap. |
45 // | 46 // |
46 // Creating a Unique<T> requires first dereferencing the handle to obtain | 47 // Creating a Unique<T> requires first dereferencing the handle to obtain |
47 // the address of the object, which is used as the hashcode and the basis for | 48 // the address of the object, which is used as the hashcode and the basis for |
48 // comparison. The object can be moved later by the GC, but comparison | 49 // comparison. The object can be moved later by the GC, but comparison |
49 // and hashing use the old address of the object, without dereferencing it. | 50 // and hashing use the old address of the object, without dereferencing it. |
50 // | 51 // |
51 // Careful! Comparison of two Uniques is only correct if both were created | 52 // Careful! Comparison of two Uniques is only correct if both were created |
52 // in the same "era" of GC or if at least one is a non-movable object. | 53 // in the same "era" of GC or if at least one is a non-movable object. |
53 template <typename T> | 54 template <typename T> |
54 class Unique V8_FINAL { | 55 class Unique V8_FINAL { |
55 public: | 56 public: |
56 // TODO(titzer): make private and introduce some builder/owner class. | 57 // TODO(titzer): make private and introduce a factory. |
57 explicit Unique(Handle<T> handle) { | 58 explicit Unique(Handle<T> handle) { |
58 if (handle.is_null()) { | 59 if (handle.is_null()) { |
59 raw_address_ = NULL; | 60 raw_address_ = NULL; |
60 } else { | 61 } else { |
| 62 // This is a best-effort check to prevent comparing Unique<T>'s created |
| 63 // in different GC eras; we require heap allocation to be disallowed at |
| 64 // creation time. |
| 65 // NOTE: we currently consider maps to be non-movable, so no special |
| 66 // assurance is required for creating a Unique<Map>. |
| 67 // TODO(titzer): other immortable immovable objects are also fine. |
| 68 ASSERT(!AllowHeapAllocation::IsAllowed() || handle->IsMap()); |
61 raw_address_ = reinterpret_cast<Address>(*handle); | 69 raw_address_ = reinterpret_cast<Address>(*handle); |
62 ASSERT_NE(raw_address_, NULL); | 70 ASSERT_NE(raw_address_, NULL); // Non-null should imply non-zero address. |
63 } | 71 } |
64 handle_ = handle; | 72 handle_ = handle; |
65 } | 73 } |
66 | 74 |
67 // TODO(titzer): this is a hack to migrate to Unique<T> incrementally. | 75 // TODO(titzer): this is a hack to migrate to Unique<T> incrementally. |
68 Unique(Address raw_address, Handle<T> handle) | 76 Unique(Address raw_address, Handle<T> handle) |
69 : raw_address_(raw_address), handle_(handle) { } | 77 : raw_address_(raw_address), handle_(handle) { } |
70 | 78 |
71 // Constructor for handling automatic up casting. | 79 // Constructor for handling automatic up casting. |
72 // Ex. Unique<JSFunction> can be passed when Unique<Object> is expected. | 80 // Eg. Unique<JSFunction> can be passed when Unique<Object> is expected. |
73 template <class S> Unique(Unique<S> uniq) { | 81 template <class S> Unique(Unique<S> uniq) { |
74 #ifdef DEBUG | 82 #ifdef DEBUG |
75 T* a = NULL; | 83 T* a = NULL; |
76 S* b = NULL; | 84 S* b = NULL; |
77 a = b; // Fake assignment to enforce type checks. | 85 a = b; // Fake assignment to enforce type checks. |
78 USE(a); | 86 USE(a); |
79 #endif | 87 #endif |
80 raw_address_ = uniq.raw_address_; | 88 raw_address_ = uniq.raw_address_; |
81 handle_ = uniq.handle_; // Creates a new handle sharing the same location. | 89 handle_ = uniq.handle_; |
82 } | 90 } |
83 | 91 |
84 template <typename U> | 92 template <typename U> |
85 bool operator==(const Unique<U>& other) const { | 93 bool operator==(const Unique<U>& other) const { |
86 ASSERT(IsInitialized() && other.IsInitialized()); | 94 ASSERT(IsInitialized() && other.IsInitialized()); |
87 return raw_address_ == other.raw_address_; | 95 return raw_address_ == other.raw_address_; |
88 } | 96 } |
89 | 97 |
90 template <typename U> | 98 template <typename U> |
91 bool operator!=(const Unique<U>& other) const { | 99 bool operator!=(const Unique<U>& other) const { |
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288 capacity_ = new_capacity; | 296 capacity_ = new_capacity; |
289 array_ = new_array; | 297 array_ = new_array; |
290 } | 298 } |
291 } | 299 } |
292 }; | 300 }; |
293 | 301 |
294 | 302 |
295 } } // namespace v8::internal | 303 } } // namespace v8::internal |
296 | 304 |
297 #endif // V8_HYDROGEN_UNIQUE_H_ | 305 #endif // V8_HYDROGEN_UNIQUE_H_ |
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