1 //===-- GDBRegistrar.cpp - Registers objects with GDB ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "JITRegistrar.h"
11 #include "llvm/ADT/DenseMap.h"
12 #include "llvm/Support/Compiler.h"
13 #include "llvm/Support/ErrorHandling.h"
14 #include "llvm/Support/Mutex.h"
15 #include "llvm/Support/MutexGuard.h"
16 #include "llvm/Support/ManagedStatic.h"
20 // This must be kept in sync with gdb/gdb/jit.h .
29 struct jit_code_entry
{
30 struct jit_code_entry
*next_entry
;
31 struct jit_code_entry
*prev_entry
;
32 const char *symfile_addr
;
33 uint64_t symfile_size
;
36 struct jit_descriptor
{
38 // This should be jit_actions_t, but we want to be specific about the
41 struct jit_code_entry
*relevant_entry
;
42 struct jit_code_entry
*first_entry
;
45 // We put information about the JITed function in this global, which the
46 // debugger reads. Make sure to specify the version statically, because the
47 // debugger checks the version before we can set it during runtime.
48 struct jit_descriptor __jit_debug_descriptor
= { 1, 0, nullptr, nullptr };
50 // Debuggers puts a breakpoint in this function.
51 LLVM_ATTRIBUTE_NOINLINE
void __jit_debug_register_code() {
52 // The noinline and the asm prevent calls to this function from being
54 #if !defined(_MSC_VER)
55 asm volatile("":::"memory");
63 // Buffer for an in-memory object file in executable memory
64 typedef llvm::DenseMap
< const char*,
65 std::pair
<std::size_t, jit_code_entry
*> >
66 RegisteredObjectBufferMap
;
68 /// Global access point for the JIT debugging interface designed for use with a
69 /// singleton toolbox. Handles thread-safe registration and deregistration of
70 /// object files that are in executable memory managed by the client of this
72 class GDBJITRegistrar
: public JITRegistrar
{
73 /// A map of in-memory object files that have been registered with the
75 RegisteredObjectBufferMap ObjectBufferMap
;
78 /// Instantiates the JIT service.
79 GDBJITRegistrar() : ObjectBufferMap() {}
81 /// Unregisters each object that was previously registered and releases all
82 /// internal resources.
83 virtual ~GDBJITRegistrar();
85 /// Creates an entry in the JIT registry for the buffer @p Object,
86 /// which must contain an object file in executable memory with any
87 /// debug information for the debugger.
88 void registerObject(const ObjectBuffer
&Object
) override
;
90 /// Removes the internal registration of @p Object, and
91 /// frees associated resources.
92 /// Returns true if @p Object was found in ObjectBufferMap.
93 bool deregisterObject(const ObjectBuffer
&Object
) override
;
96 /// Deregister the debug info for the given object file from the debugger
97 /// and delete any temporary copies. This private method does not remove
98 /// the function from Map so that it can be called while iterating over Map.
99 void deregisterObjectInternal(RegisteredObjectBufferMap::iterator I
);
102 /// Lock used to serialize all jit registration events, since they
103 /// modify global variables.
104 ManagedStatic
<sys::Mutex
> JITDebugLock
;
106 /// Do the registration.
107 void NotifyDebugger(jit_code_entry
* JITCodeEntry
) {
108 __jit_debug_descriptor
.action_flag
= JIT_REGISTER_FN
;
110 // Insert this entry at the head of the list.
111 JITCodeEntry
->prev_entry
= nullptr;
112 jit_code_entry
* NextEntry
= __jit_debug_descriptor
.first_entry
;
113 JITCodeEntry
->next_entry
= NextEntry
;
115 NextEntry
->prev_entry
= JITCodeEntry
;
117 __jit_debug_descriptor
.first_entry
= JITCodeEntry
;
118 __jit_debug_descriptor
.relevant_entry
= JITCodeEntry
;
119 __jit_debug_register_code();
122 GDBJITRegistrar::~GDBJITRegistrar() {
123 // Free all registered object files.
124 llvm::MutexGuard
locked(*JITDebugLock
);
125 for (RegisteredObjectBufferMap::iterator I
= ObjectBufferMap
.begin(), E
= ObjectBufferMap
.end();
127 // Call the private method that doesn't update the map so our iterator
129 deregisterObjectInternal(I
);
131 ObjectBufferMap
.clear();
134 void GDBJITRegistrar::registerObject(const ObjectBuffer
&Object
) {
136 const char *Buffer
= Object
.getBufferStart();
137 size_t Size
= Object
.getBufferSize();
139 assert(Buffer
&& "Attempt to register a null object with a debugger.");
140 llvm::MutexGuard
locked(*JITDebugLock
);
141 assert(ObjectBufferMap
.find(Buffer
) == ObjectBufferMap
.end() &&
142 "Second attempt to perform debug registration.");
143 jit_code_entry
* JITCodeEntry
= new jit_code_entry();
146 llvm::report_fatal_error(
147 "Allocation failed when registering a JIT entry!\n");
149 JITCodeEntry
->symfile_addr
= Buffer
;
150 JITCodeEntry
->symfile_size
= Size
;
152 ObjectBufferMap
[Buffer
] = std::make_pair(Size
, JITCodeEntry
);
153 NotifyDebugger(JITCodeEntry
);
157 bool GDBJITRegistrar::deregisterObject(const ObjectBuffer
& Object
) {
158 const char *Buffer
= Object
.getBufferStart();
159 llvm::MutexGuard
locked(*JITDebugLock
);
160 RegisteredObjectBufferMap::iterator I
= ObjectBufferMap
.find(Buffer
);
162 if (I
!= ObjectBufferMap
.end()) {
163 deregisterObjectInternal(I
);
164 ObjectBufferMap
.erase(I
);
170 void GDBJITRegistrar::deregisterObjectInternal(
171 RegisteredObjectBufferMap::iterator I
) {
173 jit_code_entry
*& JITCodeEntry
= I
->second
.second
;
175 // Do the unregistration.
177 __jit_debug_descriptor
.action_flag
= JIT_UNREGISTER_FN
;
179 // Remove the jit_code_entry from the linked list.
180 jit_code_entry
* PrevEntry
= JITCodeEntry
->prev_entry
;
181 jit_code_entry
* NextEntry
= JITCodeEntry
->next_entry
;
184 NextEntry
->prev_entry
= PrevEntry
;
187 PrevEntry
->next_entry
= NextEntry
;
190 assert(__jit_debug_descriptor
.first_entry
== JITCodeEntry
);
191 __jit_debug_descriptor
.first_entry
= NextEntry
;
194 // Tell the debugger which entry we removed, and unregister the code.
195 __jit_debug_descriptor
.relevant_entry
= JITCodeEntry
;
196 __jit_debug_register_code();
200 JITCodeEntry
= nullptr;
203 llvm::ManagedStatic
<GDBJITRegistrar
> TheRegistrar
;
209 JITRegistrar
& JITRegistrar::getGDBRegistrar() {
210 return *TheRegistrar
;