LLVM  6.0.0svn
GDBRegistrationListener.cpp
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1 //===----- GDBRegistrationListener.cpp - Registers objects with GDB -------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/ADT/DenseMap.h"
12 #include "llvm/Object/ObjectFile.h"
13 #include "llvm/Support/Compiler.h"
16 #include "llvm/Support/Mutex.h"
18 
19 using namespace llvm;
20 using namespace llvm::object;
21 
22 // This must be kept in sync with gdb/gdb/jit.h .
23 extern "C" {
24 
25  typedef enum {
29  } jit_actions_t;
30 
31  struct jit_code_entry {
34  const char *symfile_addr;
35  uint64_t symfile_size;
36  };
37 
38  struct jit_descriptor {
40  // This should be jit_actions_t, but we want to be specific about the
41  // bit-width.
45  };
46 
47  // We put information about the JITed function in this global, which the
48  // debugger reads. Make sure to specify the version statically, because the
49  // debugger checks the version before we can set it during runtime.
50  struct jit_descriptor __jit_debug_descriptor = { 1, 0, nullptr, nullptr };
51 
52  // Debuggers puts a breakpoint in this function.
54  // The noinline and the asm prevent calls to this function from being
55  // optimized out.
56 #if !defined(_MSC_VER)
57  asm volatile("":::"memory");
58 #endif
59  }
60 
61 }
62 
63 namespace {
64 
65 struct RegisteredObjectInfo {
66  RegisteredObjectInfo() {}
67 
68  RegisteredObjectInfo(std::size_t Size, jit_code_entry *Entry,
70  : Size(Size), Entry(Entry), Obj(std::move(Obj)) {}
71 
72  std::size_t Size;
73  jit_code_entry *Entry;
75 };
76 
77 // Buffer for an in-memory object file in executable memory
79  RegisteredObjectBufferMap;
80 
81 /// Global access point for the JIT debugging interface designed for use with a
82 /// singleton toolbox. Handles thread-safe registration and deregistration of
83 /// object files that are in executable memory managed by the client of this
84 /// class.
85 class GDBJITRegistrationListener : public JITEventListener {
86  /// A map of in-memory object files that have been registered with the
87  /// JIT interface.
88  RegisteredObjectBufferMap ObjectBufferMap;
89 
90 public:
91  /// Instantiates the JIT service.
92  GDBJITRegistrationListener() : ObjectBufferMap() {}
93 
94  /// Unregisters each object that was previously registered and releases all
95  /// internal resources.
96  ~GDBJITRegistrationListener() override;
97 
98  /// Creates an entry in the JIT registry for the buffer @p Object,
99  /// which must contain an object file in executable memory with any
100  /// debug information for the debugger.
101  void NotifyObjectEmitted(const ObjectFile &Object,
102  const RuntimeDyld::LoadedObjectInfo &L) override;
103 
104  /// Removes the internal registration of @p Object, and
105  /// frees associated resources.
106  /// Returns true if @p Object was found in ObjectBufferMap.
107  void NotifyFreeingObject(const ObjectFile &Object) override;
108 
109 private:
110  /// Deregister the debug info for the given object file from the debugger
111  /// and delete any temporary copies. This private method does not remove
112  /// the function from Map so that it can be called while iterating over Map.
113  void deregisterObjectInternal(RegisteredObjectBufferMap::iterator I);
114 };
115 
116 /// Lock used to serialize all jit registration events, since they
117 /// modify global variables.
118 ManagedStatic<sys::Mutex> JITDebugLock;
119 
120 /// Do the registration.
121 void NotifyDebugger(jit_code_entry* JITCodeEntry) {
123 
124  // Insert this entry at the head of the list.
125  JITCodeEntry->prev_entry = nullptr;
127  JITCodeEntry->next_entry = NextEntry;
128  if (NextEntry) {
129  NextEntry->prev_entry = JITCodeEntry;
130  }
131  __jit_debug_descriptor.first_entry = JITCodeEntry;
132  __jit_debug_descriptor.relevant_entry = JITCodeEntry;
134 }
135 
136 GDBJITRegistrationListener::~GDBJITRegistrationListener() {
137  // Free all registered object files.
138  llvm::MutexGuard locked(*JITDebugLock);
139  for (RegisteredObjectBufferMap::iterator I = ObjectBufferMap.begin(),
140  E = ObjectBufferMap.end();
141  I != E; ++I) {
142  // Call the private method that doesn't update the map so our iterator
143  // doesn't break.
144  deregisterObjectInternal(I);
145  }
146  ObjectBufferMap.clear();
147 }
148 
149 void GDBJITRegistrationListener::NotifyObjectEmitted(
150  const ObjectFile &Object,
152 
153  OwningBinary<ObjectFile> DebugObj = L.getObjectForDebug(Object);
154 
155  // Bail out if debug objects aren't supported.
156  if (!DebugObj.getBinary())
157  return;
158 
159  const char *Buffer = DebugObj.getBinary()->getMemoryBufferRef().getBufferStart();
160  size_t Size = DebugObj.getBinary()->getMemoryBufferRef().getBufferSize();
161 
162  const char *Key = Object.getMemoryBufferRef().getBufferStart();
163 
164  assert(Key && "Attempt to register a null object with a debugger.");
165  llvm::MutexGuard locked(*JITDebugLock);
166  assert(ObjectBufferMap.find(Key) == ObjectBufferMap.end() &&
167  "Second attempt to perform debug registration.");
168  jit_code_entry* JITCodeEntry = new jit_code_entry();
169 
170  if (!JITCodeEntry) {
172  "Allocation failed when registering a JIT entry!\n");
173  } else {
174  JITCodeEntry->symfile_addr = Buffer;
175  JITCodeEntry->symfile_size = Size;
176 
177  ObjectBufferMap[Key] = RegisteredObjectInfo(Size, JITCodeEntry,
178  std::move(DebugObj));
179  NotifyDebugger(JITCodeEntry);
180  }
181 }
182 
183 void GDBJITRegistrationListener::NotifyFreeingObject(const ObjectFile& Object) {
184  const char *Key = Object.getMemoryBufferRef().getBufferStart();
185  llvm::MutexGuard locked(*JITDebugLock);
186  RegisteredObjectBufferMap::iterator I = ObjectBufferMap.find(Key);
187 
188  if (I != ObjectBufferMap.end()) {
189  deregisterObjectInternal(I);
190  ObjectBufferMap.erase(I);
191  }
192 }
193 
194 void GDBJITRegistrationListener::deregisterObjectInternal(
195  RegisteredObjectBufferMap::iterator I) {
196 
197  jit_code_entry*& JITCodeEntry = I->second.Entry;
198 
199  // Do the unregistration.
200  {
202 
203  // Remove the jit_code_entry from the linked list.
204  jit_code_entry* PrevEntry = JITCodeEntry->prev_entry;
205  jit_code_entry* NextEntry = JITCodeEntry->next_entry;
206 
207  if (NextEntry) {
208  NextEntry->prev_entry = PrevEntry;
209  }
210  if (PrevEntry) {
211  PrevEntry->next_entry = NextEntry;
212  }
213  else {
214  assert(__jit_debug_descriptor.first_entry == JITCodeEntry);
216  }
217 
218  // Tell the debugger which entry we removed, and unregister the code.
219  __jit_debug_descriptor.relevant_entry = JITCodeEntry;
221  }
222 
223  delete JITCodeEntry;
224  JITCodeEntry = nullptr;
225 }
226 
228 
229 } // end namespace
230 
231 namespace llvm {
232 
234  return &*GDBRegListener;
235 }
236 
237 } // namespace llvm
Information about the loaded object.
Definition: RuntimeDyld.h:69
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:115
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
JITEventListener - Abstract interface for use by the JIT to notify clients about significant events d...
static JITEventListener * createGDBRegistrationListener()
This class is the base class for all object file types.
Definition: ObjectFile.h:189
const char * symfile_addr
struct jit_descriptor __jit_debug_descriptor
Key
PAL metadata keys.
MemoryBufferRef getMemoryBufferRef() const
Definition: Binary.cpp:43
struct jit_code_entry * first_entry
Instances of this class acquire a given Mutex Lock when constructed and hold that lock until destruct...
Definition: MutexGuard.h:27
size_t getBufferSize() const
Definition: MemoryBuffer.h:176
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
LLVM_ATTRIBUTE_NOINLINE void __jit_debug_register_code()
virtual object::OwningBinary< object::ObjectFile > getObjectForDebug(const object::ObjectFile &Obj) const =0
#define LLVM_ATTRIBUTE_NOINLINE
LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, mark a method "not for inl...
Definition: Compiler.h:186
struct jit_code_entry * prev_entry
uint64_t symfile_size
struct jit_code_entry * next_entry
#define I(x, y, z)
Definition: MD5.cpp:58
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
const char * getBufferStart() const
Definition: MemoryBuffer.h:174
struct jit_code_entry * relevant_entry
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
ManagedStatic - This transparently changes the behavior of global statics to be lazily constructed on...
Definition: ManagedStatic.h:61