Runtime: Avoid instantiating call_once on Darwin by using cross-platf…

…orm Lazy definitions.
shijunlin · Nov 16, 2015 · dc26310 · dc26310
1 parent 6d064d1
commit dc26310
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Showing 2 changed files with 24 additions and 22 deletions.
diff --git a/include/swift/Basic/Lazy.h b/include/swift/Basic/Lazy.h
@@ -22,16 +22,22 @@
 
 namespace swift {
 
+#ifdef __APPLE__
+  using OnceToken_t = dispatch_once_t;
+# define SWIFT_ONCE_F(TOKEN, FUNC, CONTEXT) \
+  dispatch_once_f(&TOKEN, CONTEXT, FUNC)
+#else
+  using OnceToken_t = std::once_flag;
+# define SWIFT_ONCE_F(TOKEN, FUNC, CONTEXT) \
+  std::call_once(TOKEN, FUNC, CONTEXT)
+#endif
+
 /// A template for lazily-constructed, zero-initialized, leaked-on-exit
 /// global objects.
 template <class T> class Lazy {
   typename std::aligned_storage<sizeof(T), alignof(T)>::type Value;
 
-#ifdef __APPLE__
-  dispatch_once_t OnceToken;
-#else
-  std::once_flag OnceToken;
-#endif
+  OnceToken_t OnceToken;
 
 public:
   T &get();
@@ -59,11 +65,7 @@ template <typename T> inline T &Lazy<T>::get() {
   static_assert(std::is_literal_type<Lazy<T>>::value,
                 "Lazy<T> must be a literal type");
 
-#ifdef __APPLE__
-  dispatch_once_f(&OnceToken, this, lazyInitCallback);
-#else
-  std::call_once(OnceToken, lazyInitCallback, this);
-#endif
+  SWIFT_ONCE_F(OnceToken, lazyInitCallback, this);
   return unsafeGetAlreadyInitialized();
 }
 

diff --git a/stdlib/public/runtime/Casting.cpp b/stdlib/public/runtime/Casting.cpp
@@ -2188,8 +2188,6 @@ const {
 #define SWIFT_PROTOCOL_CONFORMANCES_SECTION ".swift2_protocol_conformances_start"
 #endif
 
-// FIXME: Implement this callback on non-apple platforms.
-
 // std:once_flag token to install the dyld callback to enqueue images for
 // protocol conformance lookup.
 static std::once_flag InstallProtocolConformanceAddImageCallbackOnce;
@@ -2385,23 +2383,25 @@ static int _addImageProtocolConformances(struct dl_phdr_info *info,
 #endif
 
 static void installCallbacksToInspectDylib() {
-  // TODO: Generic types, subclasses, foreign classes
-  std::call_once(InstallProtocolConformanceAddImageCallbackOnce, [](){
-#if defined(__APPLE__) && defined(__MACH__)
+  static OnceToken_t token;
+  auto callback = [](void*) {
+  #if defined(__APPLE__) && defined(__MACH__)
     // Install our dyld callback if we haven't already.
-    // Dyld will invoke this on our behalf for all images that have already been
-    // loaded.
+    // Dyld will invoke this on our behalf for all images that have already
+    // been loaded.
     _dyld_register_func_for_add_image(_addImageProtocolConformances);
-#elif defined(__ELF__)
+  #elif defined(__ELF__)
     // Search the loaded dls. Unlike the above, this only searches the already
     // loaded ones.
     // FIXME: Find a way to have this continue to happen after.
     // rdar://problem/19045112
     dl_iterate_phdr(_addImageProtocolConformances, nullptr);
-#else
-#error No known mechanism to inspect loaded dynamic libraries on this platform.
-#endif
-  });
+  #else
+  # error No known mechanism to inspect dynamic libraries on this platform.
+  #endif
+  };
+
+  SWIFT_ONCE_F(token, callback, nullptr);
 }
 
 static size_t hashTypeProtocolPair(const void *type,