1 //===- llvm/Support/ThreadLocal.h - Thread Local Data ------------*- C++ -*-===//
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 // This file declares the llvm::sys::ThreadLocal class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_THREADLOCAL_H
15 #define LLVM_SUPPORT_THREADLOCAL_H
16 
17 #include "llvm/Support/DataTypes.h"
18 #include "llvm/Support/Threading.h"
19 #include <cassert>
20 
21 namespace llvm {
22   namespace sys {
23     // ThreadLocalImpl - Common base class of all ThreadLocal instantiations.
24     // YOU SHOULD NEVER USE THIS DIRECTLY.
25     class ThreadLocalImpl {
26       typedef uint64_t ThreadLocalDataTy;
27       /// \brief Platform-specific thread local data.
28       ///
29       /// This is embedded in the class and we avoid malloc'ing/free'ing it,
30       /// to make this class more safe for use along with CrashRecoveryContext.
31       union {
32         char data[sizeof(ThreadLocalDataTy)];
33         ThreadLocalDataTy align_data;
34       };
35     public:
36       ThreadLocalImpl();
37       virtual ~ThreadLocalImpl();
38       void setInstance(const void* d);
39       void *getInstance();
40       void removeInstance();
41     };
42 
43     /// ThreadLocal - A class used to abstract thread-local storage.  It holds,
44     /// for each thread, a pointer a single object of type T.
45     template<class T>
46     class ThreadLocal : public ThreadLocalImpl {
47     public:
ThreadLocal()48       ThreadLocal() : ThreadLocalImpl() { }
49 
50       /// get - Fetches a pointer to the object associated with the current
51       /// thread.  If no object has yet been associated, it returns NULL;
get()52       T* get() { return static_cast<T*>(getInstance()); }
53 
54       // set - Associates a pointer to an object with the current thread.
set(T * d)55       void set(T* d) { setInstance(d); }
56 
57       // erase - Removes the pointer associated with the current thread.
erase()58       void erase() { removeInstance(); }
59     };
60   }
61 }
62 
63 #endif
64