Thu, 07 Apr 2011 09:53:20 -0700
7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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25 #ifndef CPU_SPARC_VM_BYTES_SPARC_HPP
26 #define CPU_SPARC_VM_BYTES_SPARC_HPP
28 #include "memory/allocation.hpp"
30 class Bytes: AllStatic {
31 public:
32 // Efficient reading and writing of unaligned unsigned data in platform-specific byte ordering
33 // Sparc needs to check for alignment.
35 // can I count on address always being a pointer to an unsigned char? Yes
37 // Returns true, if the byte ordering used by Java is different from the nativ byte ordering
38 // of the underlying machine. For example, true for Intel x86, False, for Solaris on Sparc.
39 static inline bool is_Java_byte_ordering_different() { return false; }
41 // Thus, a swap between native and Java ordering is always a no-op:
42 static inline u2 swap_u2(u2 x) { return x; }
43 static inline u4 swap_u4(u4 x) { return x; }
44 static inline u8 swap_u8(u8 x) { return x; }
46 static inline u2 get_native_u2(address p){
47 return (intptr_t(p) & 1) == 0
48 ? *(u2*)p
49 : ( u2(p[0]) << 8 )
50 | ( u2(p[1]) );
51 }
53 static inline u4 get_native_u4(address p) {
54 switch (intptr_t(p) & 3) {
55 case 0: return *(u4*)p;
57 case 2: return ( u4( ((u2*)p)[0] ) << 16 )
58 | ( u4( ((u2*)p)[1] ) );
60 default: return ( u4(p[0]) << 24 )
61 | ( u4(p[1]) << 16 )
62 | ( u4(p[2]) << 8 )
63 | u4(p[3]);
64 }
65 }
67 static inline u8 get_native_u8(address p) {
68 switch (intptr_t(p) & 7) {
69 case 0: return *(u8*)p;
71 case 4: return ( u8( ((u4*)p)[0] ) << 32 )
72 | ( u8( ((u4*)p)[1] ) );
74 case 2: return ( u8( ((u2*)p)[0] ) << 48 )
75 | ( u8( ((u2*)p)[1] ) << 32 )
76 | ( u8( ((u2*)p)[2] ) << 16 )
77 | ( u8( ((u2*)p)[3] ) );
79 default: return ( u8(p[0]) << 56 )
80 | ( u8(p[1]) << 48 )
81 | ( u8(p[2]) << 40 )
82 | ( u8(p[3]) << 32 )
83 | ( u8(p[4]) << 24 )
84 | ( u8(p[5]) << 16 )
85 | ( u8(p[6]) << 8 )
86 | u8(p[7]);
87 }
88 }
92 static inline void put_native_u2(address p, u2 x) {
93 if ( (intptr_t(p) & 1) == 0 ) *(u2*)p = x;
94 else {
95 p[0] = x >> 8;
96 p[1] = x;
97 }
98 }
100 static inline void put_native_u4(address p, u4 x) {
101 switch ( intptr_t(p) & 3 ) {
102 case 0: *(u4*)p = x;
103 break;
105 case 2: ((u2*)p)[0] = x >> 16;
106 ((u2*)p)[1] = x;
107 break;
109 default: ((u1*)p)[0] = x >> 24;
110 ((u1*)p)[1] = x >> 16;
111 ((u1*)p)[2] = x >> 8;
112 ((u1*)p)[3] = x;
113 break;
114 }
115 }
117 static inline void put_native_u8(address p, u8 x) {
118 switch ( intptr_t(p) & 7 ) {
119 case 0: *(u8*)p = x;
120 break;
122 case 4: ((u4*)p)[0] = x >> 32;
123 ((u4*)p)[1] = x;
124 break;
126 case 2: ((u2*)p)[0] = x >> 48;
127 ((u2*)p)[1] = x >> 32;
128 ((u2*)p)[2] = x >> 16;
129 ((u2*)p)[3] = x;
130 break;
132 default: ((u1*)p)[0] = x >> 56;
133 ((u1*)p)[1] = x >> 48;
134 ((u1*)p)[2] = x >> 40;
135 ((u1*)p)[3] = x >> 32;
136 ((u1*)p)[4] = x >> 24;
137 ((u1*)p)[5] = x >> 16;
138 ((u1*)p)[6] = x >> 8;
139 ((u1*)p)[7] = x;
140 }
141 }
144 // Efficient reading and writing of unaligned unsigned data in Java byte ordering (i.e. big-endian ordering)
145 // (no byte-order reversal is needed since SPARC CPUs are big-endian oriented)
146 static inline u2 get_Java_u2(address p) { return get_native_u2(p); }
147 static inline u4 get_Java_u4(address p) { return get_native_u4(p); }
148 static inline u8 get_Java_u8(address p) { return get_native_u8(p); }
150 static inline void put_Java_u2(address p, u2 x) { put_native_u2(p, x); }
151 static inline void put_Java_u4(address p, u4 x) { put_native_u4(p, x); }
152 static inline void put_Java_u8(address p, u8 x) { put_native_u8(p, x); }
153 };
155 //Reconciliation History
156 // 1.7 98/02/24 10:18:41 bytes_i486.hpp
157 // 1.10 98/04/08 18:47:57 bytes_i486.hpp
158 // 1.13 98/07/15 17:10:03 bytes_i486.hpp
159 // 1.14 98/08/13 10:38:23 bytes_i486.hpp
160 // 1.15 98/10/05 16:30:21 bytes_i486.hpp
161 // 1.17 99/06/22 16:37:35 bytes_i486.hpp
162 //End
164 #endif // CPU_SPARC_VM_BYTES_SPARC_HPP