vmStructs.hpp revision 1879:f95d63e2154a 
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24
25#ifndef SHARE_VM_RUNTIME_VMSTRUCTS_HPP
26#define SHARE_VM_RUNTIME_VMSTRUCTS_HPP
27
28#ifndef VM_STRUCTS_KERNEL
29#include "utilities/debug.hpp"
30#endif
31#ifdef COMPILER1
32#include "c1/c1_Runtime1.hpp"
33#endif
34
35// This table encapsulates the debugging information required by the
36// serviceability agent in order to run. Specifically, we need to
37// understand the layout of certain C data structures (offsets, in
38// bytes, of their fields.)
39//
40// There are alternatives for the design of this mechanism, including
41// parsing platform-specific debugging symbols from a debug build into
42// a program database. While this current mechanism can be considered
43// to be a workaround for the inability to debug arbitrary C and C++
44// programs at the present time, it does have certain advantages.
45// First, it is platform-independent, which will vastly simplify the
46// initial bringup of the system both now and on future platforms.
47// Second, it is embedded within the VM, as opposed to being in a
48// separate program database; experience has shown that whenever
49// portions of a system are decoupled, version skew is problematic.
50// Third, generating a program database, for example for a product
51// build, would probably require two builds to be done: the desired
52// product build as well as an intermediary build with the PRODUCT
53// flag turned on but also compiled with -g, leading to a doubling of
54// the time required to get a serviceability agent-debuggable product
55// build. Fourth, and very significantly, this table probably
56// preserves more information about field types than stabs do; for
57// example, it preserves the fact that a field is a "jlong" rather
58// than transforming the type according to the typedef in jni_md.h,
59// which allows the Java-side code to identify "Java-sized" fields in
60// C++ data structures. If the symbol parsing mechanism was redone
61// using stabs, it might still be necessary to have a table somewhere
62// containing this information.
63//
64// Do not change the sizes or signedness of the integer values in
65// these data structures; they are fixed over in the serviceability
66// agent's Java code (for bootstrapping).
67
68typedef struct {
69  const char* typeName;            // The type name containing the given field (example: "Klass")
70  const char* fieldName;           // The field name within the type           (example: "_name")
71  const char* typeString;          // Quoted name of the type of this field (example: "symbolOopDesc*";
72                                   // parsed in Java to ensure type correctness
73  int32_t  isStatic;               // Indicates whether following field is an offset or an address
74  uint64_t offset;                 // Offset of field within structure; only used for nonstatic fields
75  void* address;                   // Address of field; only used for static fields
76                                   // ("offset" can not be reused because of apparent SparcWorks compiler bug
77                                   // in generation of initializer data)
78} VMStructEntry;
79
80typedef struct {
81  const char* typeName;            // Type name (example: "methodOopDesc")
82  const char* superclassName;      // Superclass name, or null if none (example: "oopDesc")
83  int32_t isOopType;               // Does this type represent an oop typedef? (i.e., "methodOop" or
84                                   // "klassOop", but NOT "methodOopDesc")
85  int32_t isIntegerType;           // Does this type represent an integer type (of arbitrary size)?
86  int32_t isUnsigned;              // If so, is it unsigned?
87  uint64_t size;                   // Size, in bytes, of the type
88} VMTypeEntry;
89
90typedef struct {
91  const char* name;                // Name of constant (example: "_thread_in_native")
92  int32_t value;                   // Value of constant
93} VMIntConstantEntry;
94
95typedef struct {
96  const char* name;                // Name of constant (example: "_thread_in_native")
97  uint64_t value;                  // Value of constant
98} VMLongConstantEntry;
99
100// This class is a friend of most classes, to be able to access
101// private fields
102class VMStructs {
103public:
104  // The last entry is identified over in the serviceability agent by
105  // the fact that it has a NULL fieldName
106  static VMStructEntry localHotSpotVMStructs[];
107
108  // The last entry is identified over in the serviceability agent by
109  // the fact that it has a NULL typeName
110  static VMTypeEntry   localHotSpotVMTypes[];
111
112  // Table of integer constants required by the serviceability agent.
113  // The last entry is identified over in the serviceability agent by
114  // the fact that it has a NULL typeName
115  static VMIntConstantEntry localHotSpotVMIntConstants[];
116
117  // Table of long constants required by the serviceability agent.
118  // The last entry is identified over in the serviceability agent by
119  // the fact that it has a NULL typeName
120  static VMLongConstantEntry localHotSpotVMLongConstants[];
121
122  // This is used to run any checking code necessary for validation of
123  // the data structure (debug build only)
124  static void init();
125
126private:
127  // Look up a type in localHotSpotVMTypes using strcmp() (debug build only).
128  // Returns 1 if found, 0 if not.
129  //  debug_only(static int findType(const char* typeName);)
130  static int findType(const char* typeName);
131};
132
133#endif // SHARE_VM_RUNTIME_VMSTRUCTS_HPP
134