[PATCH] D28608: [libcxx] Don't assume __libcpp_thread_t is an integral type.

[Asiri Rathnayake via Phabricator via cfe-commits]

rmaprath created this revision.
rmaprath added reviewers: compnerd, EricWF.
rmaprath added a subscriber: cfe-commits.

We have refactored the underlying platform thread type into `__libcpp_thread_t`, but there are few places in the source where it is assumed to be an integral type.

This was discovered while trying to port `libcxx` onto a platform with a slightly wonkier threading system.


https://reviews.llvm.org/D28608

Files:
  include/__threading_support
  include/thread


Index: include/thread
===================================================================
--- include/thread
+++ include/thread
@@ -290,7 +290,7 @@
     typedef __libcpp_thread_t native_handle_type;
 
     _LIBCPP_INLINE_VISIBILITY
-    thread() _NOEXCEPT : __t_(0) {}
+    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
 #ifndef _LIBCPP_HAS_NO_VARIADICS
     template <class _Fp, class ..._Args,
               class = typename enable_if
@@ -306,16 +306,16 @@
 
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     _LIBCPP_INLINE_VISIBILITY
-    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {__t.__t_ = 0;}
+    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {__t.__t_ = _LIBCPP_NULL_THREAD;}
     _LIBCPP_INLINE_VISIBILITY
     thread& operator=(thread&& __t) _NOEXCEPT;
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
     _LIBCPP_INLINE_VISIBILITY
     void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
 
     _LIBCPP_INLINE_VISIBILITY
-    bool joinable() const _NOEXCEPT {return __t_ != 0;}
+    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
     void join();
     void detach();
     _LIBCPP_INLINE_VISIBILITY
@@ -409,10 +409,10 @@
 thread&
 thread::operator=(thread&& __t) _NOEXCEPT
 {
-    if (__t_ != 0)
+    if (!__libcpp_thread_isnull(&__t_))
         terminate();
     __t_ = __t.__t_;
-    __t.__t_ = 0;
+    __t.__t_ = _LIBCPP_NULL_THREAD;
     return *this;
 }
 
Index: include/__threading_support
===================================================================
--- include/__threading_support
+++ include/__threading_support
@@ -61,6 +61,8 @@
 typedef pthread_t __libcpp_thread_id;
 
 // Thread
+#define _LIBCPP_NULL_THREAD 0U
+
 typedef pthread_t __libcpp_thread_t;
 
 // Thrad Local Storage
@@ -86,6 +88,8 @@
 typedef DWORD __libcpp_thread_id;
 
 // Thread
+#define _LIBCPP_NULL_THREAD 0U
+
 typedef HANDLE __libcpp_thread_t;
 
 // Thread Local Storage
@@ -158,6 +162,9 @@
 
 // Thread
 _LIBCPP_THREAD_ABI_VISIBILITY
+bool __libcpp_thread_isnull(const __libcpp_thread_t *__t);
+
+_LIBCPP_THREAD_ABI_VISIBILITY
 int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
                            void *__arg);
 
@@ -309,6 +316,10 @@
 }
 
 // Thread
+bool __libcpp_thread_isnull(const __libcpp_thread_t *__t) {
+  return *__t == 0;
+}
+
 int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
                            void *__arg)
 {
@@ -506,6 +517,10 @@
   return reinterpret_cast<unsigned int>(data.__func(data.__arg));
 }
 
+bool __libcpp_thread_isnull(const __libcpp_thread_t *__t) {
+  return *__t == 0;
+}
+
 int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
                            void *__arg)
 {


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