For llvm::sys::ThreadLocalImpl instead of malloc'ing the platform-specific

thread local data, embed them in the class using a uint64_t and make sure
we get compiler errors if there's a platform where this is not big enough.

This makes ThreadLocal more safe for using it in conjunction with CrashRecoveryContext.

Related to crash in rdar://11434201.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158342 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/ThreadLocal.h

@@ -15,6 +15,7 @@
 #define LLVM_SYSTEM_THREAD_LOCAL_H
 
 #include "llvm/Support/Threading.h"
+#include "llvm/Support/DataTypes.h"
 #include <cassert>
 
 namespace llvm {
@@ -22,7 +23,12 @@ namespace llvm {
     // ThreadLocalImpl - Common base class of all ThreadLocal instantiations.
     // YOU SHOULD NEVER USE THIS DIRECTLY.
     class ThreadLocalImpl {
-      void* data;
+      typedef uint64_t ThreadLocalDataTy;
+      /// \brief Platform-specific thread local data.
+      ///
+      /// This is embedded in the class and we avoid malloc'ing/free'ing it,
+      /// to make this class more safe for use along with CrashRecoveryContext.
+      ThreadLocalDataTy data;
     public:
       ThreadLocalImpl();
       virtual ~ThreadLocalImpl();

lib/Support/ThreadLocal.cpp

@@ -41,30 +41,29 @@ namespace llvm {
 using namespace sys;
 
 ThreadLocalImpl::ThreadLocalImpl() : data(0) {
-  pthread_key_t* key = new pthread_key_t;
+  typedef int SIZE_TOO_BIG[sizeof(pthread_key_t) <= sizeof(data) ? 1 : -1];
+  pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   int errorcode = pthread_key_create(key, NULL);
   assert(errorcode == 0);
   (void) errorcode;
-  data = (void*)key;
 }
 
 ThreadLocalImpl::~ThreadLocalImpl() {
-  pthread_key_t* key = static_cast<pthread_key_t*>(data);
+  pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   int errorcode = pthread_key_delete(*key);
   assert(errorcode == 0);
   (void) errorcode;
-  delete key;
 }
 
 void ThreadLocalImpl::setInstance(const void* d) {
-  pthread_key_t* key = static_cast<pthread_key_t*>(data);
+  pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   int errorcode = pthread_setspecific(*key, d);
   assert(errorcode == 0);
   (void) errorcode;
 }
 
 const void* ThreadLocalImpl::getInstance() {
-  pthread_key_t* key = static_cast<pthread_key_t*>(data);
+  pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   return pthread_getspecific(*key);
 }
 

lib/Support/Windows/ThreadLocal.inc

@@ -22,26 +22,25 @@
 namespace llvm {
 using namespace sys;
 
-ThreadLocalImpl::ThreadLocalImpl() {
+ThreadLocalImpl::ThreadLocalImpl() : data(0) {
-  DWORD* tls = new DWORD;
+  typedef int SIZE_TOO_BIG[sizeof(DWORD) <= sizeof(data) ? 1 : -1];
+  DWORD* tls = reinterpret_cast<DWORD*>(&data);
   *tls = TlsAlloc();
   assert(*tls != TLS_OUT_OF_INDEXES);
-  data = tls;
 }
 
 ThreadLocalImpl::~ThreadLocalImpl() {
-  DWORD* tls = static_cast<DWORD*>(data);
+  DWORD* tls = reinterpret_cast<DWORD*>(&data);
   TlsFree(*tls);
-  delete tls;
 }
 
 const void* ThreadLocalImpl::getInstance() {
-  DWORD* tls = static_cast<DWORD*>(data);
+  DWORD* tls = reinterpret_cast<DWORD*>(&data);
   return TlsGetValue(*tls);
 }
 
 void ThreadLocalImpl::setInstance(const void* d){
-  DWORD* tls = static_cast<DWORD*>(data);
+  DWORD* tls = reinterpret_cast<DWORD*>(&data);
   int errorcode = TlsSetValue(*tls, const_cast<void*>(d));
   assert(errorcode != 0);
   (void)errorcode;