Mercurial > hg > truffle
annotate src/share/vm/runtime/jfieldIDWorkaround.hpp @ 1721:413ad0331a0c
6977924: Changes for 6975078 produce build error with certain gcc versions
Summary: The changes introduced for 6975078 assign badHeapOopVal to the _allocation field in the ResourceObj class. In 32 bit linux builds with certain versions of gcc this assignment will be flagged as an error while compiling allocation.cpp. In 32 bit builds the constant value badHeapOopVal (which is cast to an intptr_t) is negative. The _allocation field is typed as an unsigned intptr_t and gcc catches this as an error.
Reviewed-by: jcoomes, ysr, phh
author | johnc |
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date | Wed, 18 Aug 2010 10:59:06 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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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 jfieldIDWorkaround: AllStatic { | |
26 // This workaround is because JVMTI doesn't have distinct entry points | |
27 // for methods that use static jfieldIDs and instance jfieldIDs. | |
28 // The workaround is to steal a low-order bit: | |
29 // a 1 means the jfieldID is an instance jfieldID, | |
30 // and the rest of the word is the offset of the field. | |
31 // a 0 means the jfieldID is a static jfieldID, | |
32 // and the rest of the word is the JNIid*. | |
33 // | |
34 // Another low-order bit is used to mark if an instance field | |
35 // is accompanied by an indication of which class it applies to. | |
36 // | |
37 // Bit-format of a jfieldID (most significant first): | |
38 // address:30 instance=0:1 checked=0:1 | |
39 // offset:30 instance=1:1 checked=0:1 | |
40 // klass:23 offset:7 instance=1:1 checked=1:1 | |
41 // | |
42 // If the offset does not fit in 7 bits, or if the fieldID is | |
43 // not checked, then the checked bit is zero and the rest of | |
44 // the word (30 bits) contains only the offset. | |
45 // | |
46 private: | |
47 enum { | |
48 checked_bits = 1, | |
49 instance_bits = 1, | |
50 address_bits = BitsPerWord - checked_bits - instance_bits, | |
51 | |
52 large_offset_bits = address_bits, // unioned with address | |
53 small_offset_bits = 7, | |
54 klass_bits = address_bits - small_offset_bits, | |
55 | |
56 checked_shift = 0, | |
57 instance_shift = checked_shift + checked_bits, | |
58 address_shift = instance_shift + instance_bits, | |
59 | |
60 offset_shift = address_shift, // unioned with address | |
61 klass_shift = offset_shift + small_offset_bits, | |
62 | |
63 checked_mask_in_place = right_n_bits(checked_bits) << checked_shift, | |
64 instance_mask_in_place = right_n_bits(instance_bits) << instance_shift, | |
65 #ifndef _WIN64 | |
66 large_offset_mask = right_n_bits(large_offset_bits), | |
67 small_offset_mask = right_n_bits(small_offset_bits), | |
68 klass_mask = right_n_bits(klass_bits) | |
69 #endif | |
70 }; | |
71 | |
72 #ifdef _WIN64 | |
73 // These values are too big for Win64 | |
74 const static uintptr_t large_offset_mask = right_n_bits(large_offset_bits); | |
75 const static uintptr_t small_offset_mask = right_n_bits(small_offset_bits); | |
76 const static uintptr_t klass_mask = right_n_bits(klass_bits); | |
77 #endif | |
78 | |
79 // helper routines: | |
80 static bool is_checked_jfieldID(jfieldID id) { | |
81 uintptr_t as_uint = (uintptr_t) id; | |
82 return ((as_uint & checked_mask_in_place) != 0); | |
83 } | |
84 static intptr_t raw_instance_offset(jfieldID id) { | |
85 uintptr_t result = (uintptr_t) id >> address_shift; | |
86 if (VerifyJNIFields && is_checked_jfieldID(id)) { | |
87 result &= small_offset_mask; // cut off the hash bits | |
88 } | |
89 return (intptr_t)result; | |
90 } | |
91 static intptr_t encode_klass_hash(klassOop k, intptr_t offset); | |
92 static bool klass_hash_ok(klassOop k, jfieldID id); | |
93 static void verify_instance_jfieldID(klassOop k, jfieldID id); | |
94 | |
95 public: | |
96 static bool is_valid_jfieldID(klassOop k, jfieldID id); | |
97 | |
98 static bool is_instance_jfieldID(klassOop k, jfieldID id) { | |
99 uintptr_t as_uint = (uintptr_t) id; | |
100 return ((as_uint & instance_mask_in_place) != 0); | |
101 } | |
102 static bool is_static_jfieldID(jfieldID id) { | |
103 uintptr_t as_uint = (uintptr_t) id; | |
104 return ((as_uint & instance_mask_in_place) == 0); | |
105 } | |
106 | |
107 static jfieldID to_instance_jfieldID(klassOop k, int offset) { | |
108 intptr_t as_uint = ((offset & large_offset_mask) << offset_shift) | instance_mask_in_place; | |
109 if (VerifyJNIFields) { | |
110 as_uint |= encode_klass_hash(k, offset); | |
111 } | |
112 jfieldID result = (jfieldID) as_uint; | |
113 #ifndef ASSERT | |
114 // always verify in debug mode; switchable in anything else | |
115 if (VerifyJNIFields) | |
116 #endif // ASSERT | |
117 { | |
118 verify_instance_jfieldID(k, result); | |
119 } | |
120 assert(raw_instance_offset(result) == (offset & large_offset_mask), "extract right offset"); | |
121 return result; | |
122 } | |
123 | |
124 static intptr_t from_instance_jfieldID(klassOop k, jfieldID id) { | |
125 #ifndef ASSERT | |
126 // always verify in debug mode; switchable in anything else | |
127 if (VerifyJNIFields) | |
128 #endif // ASSERT | |
129 { | |
130 verify_instance_jfieldID(k, id); | |
131 } | |
132 return raw_instance_offset(id); | |
133 } | |
134 | |
135 static jfieldID to_static_jfieldID(JNIid* id) { | |
136 assert(id->is_static_field_id(), "from_JNIid, but not static field id"); | |
137 jfieldID result = (jfieldID) id; | |
138 assert(from_static_jfieldID(result) == id, "must produce the same static id"); | |
139 return result; | |
140 } | |
141 | |
142 static JNIid* from_static_jfieldID(jfieldID id) { | |
143 assert(jfieldIDWorkaround::is_static_jfieldID(id), | |
144 "to_JNIid, but not static jfieldID"); | |
145 JNIid* result = (JNIid*) id; | |
146 assert(result->is_static_field_id(), "to_JNIid, but not static field id"); | |
147 return result; | |
148 } | |
149 | |
150 static jfieldID to_jfieldID(instanceKlassHandle k, int offset, bool is_static) { | |
151 if (is_static) { | |
152 JNIid *id = k->jni_id_for(offset); | |
153 debug_only(id->set_is_static_field_id()); | |
154 return jfieldIDWorkaround::to_static_jfieldID(id); | |
155 } else { | |
156 return jfieldIDWorkaround::to_instance_jfieldID(k(), offset); | |
157 } | |
158 } | |
159 }; |