Mercurial > hg > graal-jvmci-8
annotate src/share/vm/runtime/registerMap.hpp @ 1716:be3f9c242c9d
6948538: CMS: BOT walkers can fall into object allocation and initialization cracks
Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode.
Reviewed-by: chrisphi, johnc, poonam
author | ysr |
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date | Mon, 16 Aug 2010 15:58:42 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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6941466: Oracle rebranding changes for Hotspot repositories
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 class JavaThread; | |
26 | |
27 // | |
28 // RegisterMap | |
29 // | |
30 // A companion structure used for stack traversal. The RegisterMap contains | |
31 // misc. information needed in order to do correct stack traversal of stack | |
32 // frames. Hence, it must always be passed in as an argument to | |
33 // frame::sender(RegisterMap*). | |
34 // | |
35 // In particular, | |
36 // 1) It provides access to the thread for which the stack belongs. The | |
37 // thread object is needed in order to get sender of a deoptimized frame. | |
38 // | |
39 // 2) It is used to pass information from a callee frame to its caller | |
40 // frame about how the frame should be traversed. This is used to let | |
41 // the caller frame take care of calling oops-do of out-going | |
42 // arguments, when the callee frame is not instantiated yet. This | |
43 // happens, e.g., when a compiled frame calls into | |
44 // resolve_virtual_call. (Hence, it is critical that the same | |
45 // RegisterMap object is used for the entire stack walk. Normally, | |
46 // this is hidden by using the StackFrameStream.) This is used when | |
47 // doing follow_oops and oops_do. | |
48 // | |
49 // 3) The RegisterMap keeps track of the values of callee-saved registers | |
50 // from frame to frame (hence, the name). For some stack traversal the | |
51 // values of the callee-saved registers does not matter, e.g., if you | |
52 // only need the static properies such as frame type, pc, and such. | |
53 // Updating of the RegisterMap can be turned off by instantiating the | |
54 // register map as: RegisterMap map(thread, false); | |
55 | |
56 class RegisterMap : public StackObj { | |
57 public: | |
58 typedef julong LocationValidType; | |
59 enum { | |
60 reg_count = ConcreteRegisterImpl::number_of_registers, | |
61 location_valid_type_size = sizeof(LocationValidType)*8, | |
62 location_valid_size = (reg_count+location_valid_type_size-1)/location_valid_type_size | |
63 }; | |
64 private: | |
65 intptr_t* _location[reg_count]; // Location of registers (intptr_t* looks better than address in the debugger) | |
66 LocationValidType _location_valid[location_valid_size]; | |
67 bool _include_argument_oops; // Should include argument_oop marked locations for compiler | |
68 JavaThread* _thread; // Reference to current thread | |
69 bool _update_map; // Tells if the register map need to be | |
70 // updated when traversing the stack | |
71 | |
72 #ifdef ASSERT | |
73 void check_location_valid(); | |
74 #else | |
75 void check_location_valid() {} | |
76 #endif | |
77 | |
78 public: | |
79 debug_only(intptr_t* _update_for_id;) // Assert that RegisterMap is not updated twice for same frame | |
80 RegisterMap(JavaThread *thread, bool update_map = true); | |
81 RegisterMap(const RegisterMap* map); | |
82 | |
83 address location(VMReg reg) const { | |
84 int index = reg->value() / location_valid_type_size; | |
85 assert(0 <= reg->value() && reg->value() < reg_count, "range check"); | |
86 assert(0 <= index && index < location_valid_size, "range check"); | |
87 if (_location_valid[index] & ((LocationValidType)1 << (reg->value() % location_valid_type_size))) { | |
88 return (address) _location[reg->value()]; | |
89 } else { | |
90 return pd_location(reg); | |
91 } | |
92 } | |
93 | |
94 void set_location(VMReg reg, address loc) { | |
95 int index = reg->value() / location_valid_type_size; | |
96 assert(0 <= reg->value() && reg->value() < reg_count, "range check"); | |
97 assert(0 <= index && index < location_valid_size, "range check"); | |
98 assert(_update_map, "updating map that does not need updating"); | |
99 _location[reg->value()] = (intptr_t*) loc; | |
100 _location_valid[index] |= ((LocationValidType)1 << (reg->value() % location_valid_type_size)); | |
101 check_location_valid(); | |
102 } | |
103 | |
104 // Called by an entry frame. | |
105 void clear(); | |
106 | |
107 bool include_argument_oops() const { return _include_argument_oops; } | |
108 void set_include_argument_oops(bool f) { _include_argument_oops = f; } | |
109 | |
110 JavaThread *thread() const { return _thread; } | |
111 bool update_map() const { return _update_map; } | |
112 | |
113 void print_on(outputStream* st) const; | |
114 void print() const; | |
115 | |
116 // the following contains the definition of pd_xxx methods | |
117 # include "incls/_registerMap_pd.hpp.incl" | |
118 }; |