| 1 | // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| 2 | // for details. All rights reserved. Use of this source code is governed by a |
| 3 | // BSD-style license that can be found in the LICENSE file. |
| 4 | |
| 5 | #include "platform/globals.h" // NOLINT |
| 6 | #if defined(HOST_OS_WINDOWS) |
| 7 | |
| 8 | #include "vm/growable_array.h" |
| 9 | #include "vm/lockers.h" |
| 10 | #include "vm/os_thread.h" |
| 11 | |
| 12 | #include <process.h> // NOLINT |
| 13 | |
| 14 | #include "platform/address_sanitizer.h" |
| 15 | #include "platform/assert.h" |
| 16 | #include "platform/safe_stack.h" |
| 17 | |
| 18 | #include "vm/flags.h" |
| 19 | |
| 20 | namespace dart { |
| 21 | |
| 22 | DEFINE_FLAG(int, |
| 23 | worker_thread_priority, |
| 24 | kMinInt, |
| 25 | "The thread priority the VM should use for new worker threads." ); |
| 26 | |
| 27 | // This flag is flipped by platform_win.cc when the process is exiting. |
| 28 | // TODO(zra): Remove once VM shuts down cleanly. |
| 29 | bool private_flag_windows_run_tls_destructors = true; |
| 30 | |
| 31 | class ThreadStartData { |
| 32 | public: |
| 33 | ThreadStartData(const char* name, |
| 34 | OSThread::ThreadStartFunction function, |
| 35 | uword parameter) |
| 36 | : name_(name), function_(function), parameter_(parameter) {} |
| 37 | |
| 38 | const char* name() const { return name_; } |
| 39 | OSThread::ThreadStartFunction function() const { return function_; } |
| 40 | uword parameter() const { return parameter_; } |
| 41 | |
| 42 | private: |
| 43 | const char* name_; |
| 44 | OSThread::ThreadStartFunction function_; |
| 45 | uword parameter_; |
| 46 | |
| 47 | DISALLOW_COPY_AND_ASSIGN(ThreadStartData); |
| 48 | }; |
| 49 | |
| 50 | // Dispatch to the thread start function provided by the caller. This trampoline |
| 51 | // is used to ensure that the thread is properly destroyed if the thread just |
| 52 | // exits. |
| 53 | static unsigned int __stdcall ThreadEntry(void* data_ptr) { |
| 54 | if (FLAG_worker_thread_priority != kMinInt) { |
| 55 | if (SetThreadPriority(GetCurrentThread(), FLAG_worker_thread_priority) == |
| 56 | 0) { |
| 57 | FATAL2("Setting thread priority to %d failed: GetLastError() = %d\n" , |
| 58 | FLAG_worker_thread_priority, GetLastError()); |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | ThreadStartData* data = reinterpret_cast<ThreadStartData*>(data_ptr); |
| 63 | |
| 64 | const char* name = data->name(); |
| 65 | OSThread::ThreadStartFunction function = data->function(); |
| 66 | uword parameter = data->parameter(); |
| 67 | delete data; |
| 68 | |
| 69 | // Create new OSThread object and set as TLS for new thread. |
| 70 | OSThread* thread = OSThread::CreateOSThread(); |
| 71 | if (thread != NULL) { |
| 72 | OSThread::SetCurrent(thread); |
| 73 | thread->set_name(name); |
| 74 | |
| 75 | // Call the supplied thread start function handing it its parameters. |
| 76 | function(parameter); |
| 77 | } |
| 78 | |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | int OSThread::Start(const char* name, |
| 83 | ThreadStartFunction function, |
| 84 | uword parameter) { |
| 85 | ThreadStartData* start_data = new ThreadStartData(name, function, parameter); |
| 86 | uint32_t tid; |
| 87 | uintptr_t thread = _beginthreadex(NULL, OSThread::GetMaxStackSize(), |
| 88 | ThreadEntry, start_data, 0, &tid); |
| 89 | if (thread == -1L || thread == 0) { |
| 90 | #ifdef DEBUG |
| 91 | fprintf(stderr, "_beginthreadex error: %d (%s)\n" , errno, strerror(errno)); |
| 92 | #endif |
| 93 | return errno; |
| 94 | } |
| 95 | |
| 96 | // Close the handle, so we don't leak the thread object. |
| 97 | CloseHandle(reinterpret_cast<HANDLE>(thread)); |
| 98 | |
| 99 | return 0; |
| 100 | } |
| 101 | |
| 102 | const ThreadId OSThread::kInvalidThreadId = 0; |
| 103 | const ThreadJoinId OSThread::kInvalidThreadJoinId = NULL; |
| 104 | |
| 105 | ThreadLocalKey OSThread::CreateThreadLocal(ThreadDestructor destructor) { |
| 106 | ThreadLocalKey key = TlsAlloc(); |
| 107 | if (key == kUnsetThreadLocalKey) { |
| 108 | FATAL1("TlsAlloc failed %d" , GetLastError()); |
| 109 | } |
| 110 | ThreadLocalData::AddThreadLocal(key, destructor); |
| 111 | return key; |
| 112 | } |
| 113 | |
| 114 | void OSThread::DeleteThreadLocal(ThreadLocalKey key) { |
| 115 | ASSERT(key != kUnsetThreadLocalKey); |
| 116 | BOOL result = TlsFree(key); |
| 117 | if (!result) { |
| 118 | FATAL1("TlsFree failed %d" , GetLastError()); |
| 119 | } |
| 120 | ThreadLocalData::RemoveThreadLocal(key); |
| 121 | } |
| 122 | |
| 123 | intptr_t OSThread::GetMaxStackSize() { |
| 124 | const int kStackSize = (128 * kWordSize * KB); |
| 125 | return kStackSize; |
| 126 | } |
| 127 | |
| 128 | ThreadId OSThread::GetCurrentThreadId() { |
| 129 | return ::GetCurrentThreadId(); |
| 130 | } |
| 131 | |
| 132 | #ifdef SUPPORT_TIMELINE |
| 133 | ThreadId OSThread::GetCurrentThreadTraceId() { |
| 134 | return ::GetCurrentThreadId(); |
| 135 | } |
| 136 | #endif // PRODUCT |
| 137 | |
| 138 | ThreadJoinId OSThread::GetCurrentThreadJoinId(OSThread* thread) { |
| 139 | ASSERT(thread != NULL); |
| 140 | // Make sure we're filling in the join id for the current thread. |
| 141 | ThreadId id = GetCurrentThreadId(); |
| 142 | ASSERT(thread->id() == id); |
| 143 | // Make sure the join_id_ hasn't been set, yet. |
| 144 | DEBUG_ASSERT(thread->join_id_ == kInvalidThreadJoinId); |
| 145 | HANDLE handle = OpenThread(SYNCHRONIZE, false, id); |
| 146 | ASSERT(handle != NULL); |
| 147 | #if defined(DEBUG) |
| 148 | thread->join_id_ = handle; |
| 149 | #endif |
| 150 | return handle; |
| 151 | } |
| 152 | |
| 153 | void OSThread::Join(ThreadJoinId id) { |
| 154 | HANDLE handle = static_cast<HANDLE>(id); |
| 155 | ASSERT(handle != NULL); |
| 156 | DWORD res = WaitForSingleObject(handle, INFINITE); |
| 157 | CloseHandle(handle); |
| 158 | ASSERT(res == WAIT_OBJECT_0); |
| 159 | } |
| 160 | |
| 161 | intptr_t OSThread::ThreadIdToIntPtr(ThreadId id) { |
| 162 | ASSERT(sizeof(id) <= sizeof(intptr_t)); |
| 163 | return static_cast<intptr_t>(id); |
| 164 | } |
| 165 | |
| 166 | ThreadId OSThread::ThreadIdFromIntPtr(intptr_t id) { |
| 167 | return static_cast<ThreadId>(id); |
| 168 | } |
| 169 | |
| 170 | bool OSThread::Compare(ThreadId a, ThreadId b) { |
| 171 | return a == b; |
| 172 | } |
| 173 | |
| 174 | bool OSThread::GetCurrentStackBounds(uword* lower, uword* upper) { |
| 175 | // On Windows stack limits for the current thread are available in |
| 176 | // the thread information block (TIB). Its fields can be accessed through |
| 177 | // FS segment register on x86 and GS segment register on x86_64. |
| 178 | #ifdef _WIN64 |
| 179 | *upper = static_cast<uword>(__readgsqword(offsetof(NT_TIB64, StackBase))); |
| 180 | #else |
| 181 | *upper = static_cast<uword>(__readfsdword(offsetof(NT_TIB, StackBase))); |
| 182 | #endif |
| 183 | // Notice that we cannot use the TIB's StackLimit for the stack end, as it |
| 184 | // tracks the end of the committed range. We're after the end of the reserved |
| 185 | // stack area (most of which will be uncommitted, most times). |
| 186 | MEMORY_BASIC_INFORMATION stack_info; |
| 187 | memset(&stack_info, 0, sizeof(MEMORY_BASIC_INFORMATION)); |
| 188 | size_t result_size = |
| 189 | VirtualQuery(&stack_info, &stack_info, sizeof(MEMORY_BASIC_INFORMATION)); |
| 190 | ASSERT(result_size >= sizeof(MEMORY_BASIC_INFORMATION)); |
| 191 | *lower = reinterpret_cast<uword>(stack_info.AllocationBase); |
| 192 | ASSERT(*upper > *lower); |
| 193 | // When the third last page of the reserved stack is accessed as a |
| 194 | // guard page, the second last page will be committed (along with removing |
| 195 | // the guard bit on the third last) _and_ a stack overflow exception |
| 196 | // is raised. |
| 197 | // |
| 198 | // http://blogs.msdn.com/b/satyem/archive/2012/08/13/thread-s-stack-memory-management.aspx |
| 199 | // explains the details. |
| 200 | ASSERT((*upper - *lower) >= (4u * 0x1000)); |
| 201 | *lower += 4 * 0x1000; |
| 202 | return true; |
| 203 | } |
| 204 | |
| 205 | #if defined(USING_SAFE_STACK) |
| 206 | NO_SANITIZE_ADDRESS |
| 207 | NO_SANITIZE_SAFE_STACK |
| 208 | uword OSThread::GetCurrentSafestackPointer() { |
| 209 | #error "SAFE_STACK is unsupported on this platform" |
| 210 | return 0; |
| 211 | } |
| 212 | |
| 213 | NO_SANITIZE_ADDRESS |
| 214 | NO_SANITIZE_SAFE_STACK |
| 215 | void OSThread::SetCurrentSafestackPointer(uword ssp) { |
| 216 | #error "SAFE_STACK is unsupported on this platform" |
| 217 | } |
| 218 | #endif |
| 219 | |
| 220 | void OSThread::SetThreadLocal(ThreadLocalKey key, uword value) { |
| 221 | ASSERT(key != kUnsetThreadLocalKey); |
| 222 | BOOL result = TlsSetValue(key, reinterpret_cast<void*>(value)); |
| 223 | if (!result) { |
| 224 | FATAL1("TlsSetValue failed %d" , GetLastError()); |
| 225 | } |
| 226 | } |
| 227 | |
| 228 | Mutex::Mutex(NOT_IN_PRODUCT(const char* name)) |
| 229 | #if !defined(PRODUCT) |
| 230 | : name_(name) |
| 231 | #endif |
| 232 | { |
| 233 | InitializeSRWLock(&data_.lock_); |
| 234 | #if defined(DEBUG) |
| 235 | // When running with assertions enabled we do track the owner. |
| 236 | owner_ = OSThread::kInvalidThreadId; |
| 237 | #endif // defined(DEBUG) |
| 238 | } |
| 239 | |
| 240 | Mutex::~Mutex() { |
| 241 | #if defined(DEBUG) |
| 242 | // When running with assertions enabled we do track the owner. |
| 243 | ASSERT(owner_ == OSThread::kInvalidThreadId); |
| 244 | #endif // defined(DEBUG) |
| 245 | } |
| 246 | |
| 247 | void Mutex::Lock() { |
| 248 | AcquireSRWLockExclusive(&data_.lock_); |
| 249 | #if defined(DEBUG) |
| 250 | // When running with assertions enabled we do track the owner. |
| 251 | owner_ = OSThread::GetCurrentThreadId(); |
| 252 | #endif // defined(DEBUG) |
| 253 | } |
| 254 | |
| 255 | bool Mutex::TryLock() { |
| 256 | if (TryAcquireSRWLockExclusive(&data_.lock_) != 0) { |
| 257 | #if defined(DEBUG) |
| 258 | // When running with assertions enabled we do track the owner. |
| 259 | owner_ = OSThread::GetCurrentThreadId(); |
| 260 | #endif // defined(DEBUG) |
| 261 | return true; |
| 262 | } |
| 263 | return false; |
| 264 | } |
| 265 | |
| 266 | void Mutex::Unlock() { |
| 267 | #if defined(DEBUG) |
| 268 | // When running with assertions enabled we do track the owner. |
| 269 | ASSERT(IsOwnedByCurrentThread()); |
| 270 | owner_ = OSThread::kInvalidThreadId; |
| 271 | #endif // defined(DEBUG) |
| 272 | ReleaseSRWLockExclusive(&data_.lock_); |
| 273 | } |
| 274 | |
| 275 | Monitor::Monitor() { |
| 276 | InitializeSRWLock(&data_.lock_); |
| 277 | InitializeConditionVariable(&data_.cond_); |
| 278 | #if defined(DEBUG) |
| 279 | // When running with assertions enabled we track the owner. |
| 280 | owner_ = OSThread::kInvalidThreadId; |
| 281 | #endif // defined(DEBUG) |
| 282 | } |
| 283 | |
| 284 | Monitor::~Monitor() { |
| 285 | #if defined(DEBUG) |
| 286 | // When running with assertions enabled we track the owner. |
| 287 | ASSERT(owner_ == OSThread::kInvalidThreadId); |
| 288 | #endif // defined(DEBUG) |
| 289 | } |
| 290 | |
| 291 | bool Monitor::TryEnter() { |
| 292 | // Attempt to pass the semaphore but return immediately. |
| 293 | if (TryAcquireSRWLockExclusive(&data_.lock_) != 0) { |
| 294 | #if defined(DEBUG) |
| 295 | // When running with assertions enabled we do track the owner. |
| 296 | ASSERT(owner_ == OSThread::kInvalidThreadId); |
| 297 | owner_ = OSThread::GetCurrentThreadId(); |
| 298 | #endif // defined(DEBUG) |
| 299 | return true; |
| 300 | } |
| 301 | return false; |
| 302 | } |
| 303 | |
| 304 | void Monitor::Enter() { |
| 305 | AcquireSRWLockExclusive(&data_.lock_); |
| 306 | |
| 307 | #if defined(DEBUG) |
| 308 | // When running with assertions enabled we track the owner. |
| 309 | ASSERT(owner_ == OSThread::kInvalidThreadId); |
| 310 | owner_ = OSThread::GetCurrentThreadId(); |
| 311 | #endif // defined(DEBUG) |
| 312 | } |
| 313 | |
| 314 | void Monitor::Exit() { |
| 315 | #if defined(DEBUG) |
| 316 | // When running with assertions enabled we track the owner. |
| 317 | ASSERT(IsOwnedByCurrentThread()); |
| 318 | owner_ = OSThread::kInvalidThreadId; |
| 319 | #endif // defined(DEBUG) |
| 320 | |
| 321 | ReleaseSRWLockExclusive(&data_.lock_); |
| 322 | } |
| 323 | |
| 324 | Monitor::WaitResult Monitor::Wait(int64_t millis) { |
| 325 | #if defined(DEBUG) |
| 326 | // When running with assertions enabled we track the owner. |
| 327 | ASSERT(IsOwnedByCurrentThread()); |
| 328 | ThreadId saved_owner = owner_; |
| 329 | owner_ = OSThread::kInvalidThreadId; |
| 330 | #endif // defined(DEBUG) |
| 331 | |
| 332 | Monitor::WaitResult retval = kNotified; |
| 333 | if (millis == kNoTimeout) { |
| 334 | SleepConditionVariableSRW(&data_.cond_, &data_.lock_, INFINITE, 0); |
| 335 | } else { |
| 336 | // Wait for the given period of time for a Notify or a NotifyAll |
| 337 | // event. |
| 338 | if (!SleepConditionVariableSRW(&data_.cond_, &data_.lock_, millis, 0)) { |
| 339 | ASSERT(GetLastError() == ERROR_TIMEOUT); |
| 340 | retval = kTimedOut; |
| 341 | } |
| 342 | } |
| 343 | |
| 344 | #if defined(DEBUG) |
| 345 | // When running with assertions enabled we track the owner. |
| 346 | ASSERT(owner_ == OSThread::kInvalidThreadId); |
| 347 | owner_ = OSThread::GetCurrentThreadId(); |
| 348 | ASSERT(owner_ == saved_owner); |
| 349 | #endif // defined(DEBUG) |
| 350 | return retval; |
| 351 | } |
| 352 | |
| 353 | Monitor::WaitResult Monitor::WaitMicros(int64_t micros) { |
| 354 | // TODO(johnmccutchan): Investigate sub-millisecond sleep times on Windows. |
| 355 | int64_t millis = micros / kMicrosecondsPerMillisecond; |
| 356 | if ((millis * kMicrosecondsPerMillisecond) < micros) { |
| 357 | // We've been asked to sleep for a fraction of a millisecond, |
| 358 | // this isn't supported on Windows. Bumps milliseconds up by one |
| 359 | // so that we never return too early. We likely return late though. |
| 360 | millis += 1; |
| 361 | } |
| 362 | return Wait(millis); |
| 363 | } |
| 364 | |
| 365 | void Monitor::Notify() { |
| 366 | // When running with assertions enabled we track the owner. |
| 367 | ASSERT(IsOwnedByCurrentThread()); |
| 368 | WakeConditionVariable(&data_.cond_); |
| 369 | } |
| 370 | |
| 371 | void Monitor::NotifyAll() { |
| 372 | // When running with assertions enabled we track the owner. |
| 373 | ASSERT(IsOwnedByCurrentThread()); |
| 374 | WakeAllConditionVariable(&data_.cond_); |
| 375 | } |
| 376 | |
| 377 | void ThreadLocalData::AddThreadLocal(ThreadLocalKey key, |
| 378 | ThreadDestructor destructor) { |
| 379 | ASSERT(thread_locals_ != NULL); |
| 380 | if (destructor == NULL) { |
| 381 | // We only care about thread locals with destructors. |
| 382 | return; |
| 383 | } |
| 384 | MutexLocker ml(mutex_); |
| 385 | #if defined(DEBUG) |
| 386 | // Verify that we aren't added twice. |
| 387 | for (intptr_t i = 0; i < thread_locals_->length(); i++) { |
| 388 | const ThreadLocalEntry& entry = thread_locals_->At(i); |
| 389 | ASSERT(entry.key() != key); |
| 390 | } |
| 391 | #endif |
| 392 | // Add to list. |
| 393 | thread_locals_->Add(ThreadLocalEntry(key, destructor)); |
| 394 | } |
| 395 | |
| 396 | void ThreadLocalData::RemoveThreadLocal(ThreadLocalKey key) { |
| 397 | ASSERT(thread_locals_ != NULL); |
| 398 | MutexLocker ml(mutex_); |
| 399 | intptr_t i = 0; |
| 400 | for (; i < thread_locals_->length(); i++) { |
| 401 | const ThreadLocalEntry& entry = thread_locals_->At(i); |
| 402 | if (entry.key() == key) { |
| 403 | break; |
| 404 | } |
| 405 | } |
| 406 | if (i == thread_locals_->length()) { |
| 407 | // Not found. |
| 408 | return; |
| 409 | } |
| 410 | thread_locals_->RemoveAt(i); |
| 411 | } |
| 412 | |
| 413 | // This function is executed on the thread that is exiting. It is invoked |
| 414 | // by |OnDartThreadExit| (see below for notes on TLS destructors on Windows). |
| 415 | void ThreadLocalData::RunDestructors() { |
| 416 | // If an OS thread is created but ThreadLocalData::Init has not yet been |
| 417 | // called, this method still runs. If this happens, there's nothing to clean |
| 418 | // up here. See issue 33826. |
| 419 | if (thread_locals_ == NULL) { |
| 420 | return; |
| 421 | } |
| 422 | ASSERT(mutex_ != NULL); |
| 423 | MutexLocker ml(mutex_); |
| 424 | for (intptr_t i = 0; i < thread_locals_->length(); i++) { |
| 425 | const ThreadLocalEntry& entry = thread_locals_->At(i); |
| 426 | // We access the exiting thread's TLS variable here. |
| 427 | void* p = reinterpret_cast<void*>(OSThread::GetThreadLocal(entry.key())); |
| 428 | // We invoke the constructor here. |
| 429 | entry.destructor()(p); |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | Mutex* ThreadLocalData::mutex_ = NULL; |
| 434 | MallocGrowableArray<ThreadLocalEntry>* ThreadLocalData::thread_locals_ = NULL; |
| 435 | |
| 436 | void ThreadLocalData::Init() { |
| 437 | mutex_ = new Mutex(); |
| 438 | thread_locals_ = new MallocGrowableArray<ThreadLocalEntry>(); |
| 439 | } |
| 440 | |
| 441 | void ThreadLocalData::Cleanup() { |
| 442 | if (mutex_ != NULL) { |
| 443 | delete mutex_; |
| 444 | mutex_ = NULL; |
| 445 | } |
| 446 | if (thread_locals_ != NULL) { |
| 447 | delete thread_locals_; |
| 448 | thread_locals_ = NULL; |
| 449 | } |
| 450 | } |
| 451 | |
| 452 | } // namespace dart |
| 453 | |
| 454 | // The following was adapted from Chromium: |
| 455 | // src/base/threading/thread_local_storage_win.cc |
| 456 | |
| 457 | // Thread Termination Callbacks. |
| 458 | // Windows doesn't support a per-thread destructor with its |
| 459 | // TLS primitives. So, we build it manually by inserting a |
| 460 | // function to be called on each thread's exit. |
| 461 | // This magic is from http://www.codeproject.com/threads/tls.asp |
| 462 | // and it works for VC++ 7.0 and later. |
| 463 | |
| 464 | // Force a reference to _tls_used to make the linker create the TLS directory |
| 465 | // if it's not already there. (e.g. if __declspec(thread) is not used). |
| 466 | // Force a reference to p_thread_callback_dart to prevent whole program |
| 467 | // optimization from discarding the variable. |
| 468 | #ifdef _WIN64 |
| 469 | |
| 470 | #pragma comment(linker, "/INCLUDE:_tls_used") |
| 471 | #pragma comment(linker, "/INCLUDE:p_thread_callback_dart") |
| 472 | |
| 473 | #else // _WIN64 |
| 474 | |
| 475 | #pragma comment(linker, "/INCLUDE:__tls_used") |
| 476 | #pragma comment(linker, "/INCLUDE:_p_thread_callback_dart") |
| 477 | |
| 478 | #endif // _WIN64 |
| 479 | |
| 480 | // Static callback function to call with each thread termination. |
| 481 | void NTAPI OnDartThreadExit(PVOID module, DWORD reason, PVOID reserved) { |
| 482 | if (!dart::private_flag_windows_run_tls_destructors) { |
| 483 | return; |
| 484 | } |
| 485 | // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+ |
| 486 | // and on W2K and W2K3. So don't assume it is sent. |
| 487 | if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason) { |
| 488 | dart::ThreadLocalData::RunDestructors(); |
| 489 | } |
| 490 | } |
| 491 | |
| 492 | // .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are |
| 493 | // called automatically by the OS loader code (not the CRT) when the module is |
| 494 | // loaded and on thread creation. They are NOT called if the module has been |
| 495 | // loaded by a LoadLibrary() call. It must have implicitly been loaded at |
| 496 | // process startup. |
| 497 | // By implicitly loaded, I mean that it is directly referenced by the main EXE |
| 498 | // or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being |
| 499 | // implicitly loaded. |
| 500 | // |
| 501 | // See VC\crt\src\tlssup.c for reference. |
| 502 | |
| 503 | // extern "C" suppresses C++ name mangling so we know the symbol name for the |
| 504 | // linker /INCLUDE:symbol pragma above. |
| 505 | extern "C" { |
| 506 | // The linker must not discard p_thread_callback_dart. (We force a reference |
| 507 | // to this variable with a linker /INCLUDE:symbol pragma to ensure that.) If |
| 508 | // this variable is discarded, the OnDartThreadExit function will never be |
| 509 | // called. |
| 510 | #ifdef _WIN64 |
| 511 | |
| 512 | // .CRT section is merged with .rdata on x64 so it must be constant data. |
| 513 | #pragma const_seg(".CRT$XLB") |
| 514 | // When defining a const variable, it must have external linkage to be sure the |
| 515 | // linker doesn't discard it. |
| 516 | extern const PIMAGE_TLS_CALLBACK p_thread_callback_dart; |
| 517 | const PIMAGE_TLS_CALLBACK p_thread_callback_dart = OnDartThreadExit; |
| 518 | |
| 519 | // Reset the default section. |
| 520 | #pragma const_seg() |
| 521 | |
| 522 | #else // _WIN64 |
| 523 | |
| 524 | #pragma data_seg(".CRT$XLB") |
| 525 | PIMAGE_TLS_CALLBACK p_thread_callback_dart = OnDartThreadExit; |
| 526 | |
| 527 | // Reset the default section. |
| 528 | #pragma data_seg() |
| 529 | |
| 530 | #endif // _WIN64 |
| 531 | } // extern "C" |
| 532 | |
| 533 | #endif // defined(HOST_OS_WINDOWS) |
| 534 | |