Support __thread keyword when compiling with Clang on OS X.

phusion · Jul 20, 2012 · 81101ee · 81101ee
1 parent 3aa07ec
commit 81101ee
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Showing 3 changed files with 37 additions and 32 deletions.
diff --git a/ext/oxt/backtrace.cpp b/ext/oxt/backtrace.cpp
@@ -2,7 +2,7 @@
  * OXT - OS eXtensions for boosT
  * Provides important functionality necessary for writing robust server software.
  *
- * Copyright (c) 2010 Phusion
+ * Copyright (c) 2010, 2011, 2012 Phusion
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -29,6 +29,7 @@
 #include <sstream>
 #include <cstring>
 #include "backtrace.hpp"
+#include "macros.hpp"
 
 namespace oxt {
 
@@ -54,31 +55,8 @@ namespace {
 /*
  * boost::thread_specific_storage is pretty expensive. So we use the __thread
  * keyword whenever possible - that's almost free.
- * GCC supports the __thread keyword on x86 since version 3.3, but versions earlier
- * than 4.1.2 have bugs (http://gcc.gnu.org/ml/gcc-bugs/2006-09/msg02275.html).
  */
-
-#ifndef OXT_GCC_VERSION
-	#define OXT_GCC_VERSION (__GNUC__ * 10000 \
-                               + __GNUC_MINOR__ * 100 \
-                               + __GNUC_PATCHLEVEL__)
-#endif
-
-/*
- * FreeBSD 5 supports the __thread keyword, and everything works fine in
- * micro-tests, but in mod_passenger the thread-local variables are initialized
- * to unaligned addresses for some weird reason, thereby causing bus errors.
- *
- * GCC on OpenBSD supports __thread, but any access to such a variable
- * results in a segfault.
- *
- * Solaris does support __thread, but often it's not compiled into default GCC 
- * packages (not to mention it's not available for Sparc). Playing it safe...
- *
- * MacOS X doesn't support __thread at all.
- */
-#if OXT_GCC_VERSION >= 40102 && !defined(__FreeBSD__) && \
-   !defined(__SOLARIS__) && !defined(__OpenBSD__) && !defined(__APPLE__)
+#ifdef OXT_THREAD_LOCAL_KEYWORD_SUPPORTED
 	static __thread backtrace_data *thread_specific_backtrace_data;
 
 	void

diff --git a/ext/oxt/macros.hpp b/ext/oxt/macros.hpp
@@ -2,7 +2,7 @@
  * OXT - OS eXtensions for boosT
  * Provides important functionality necessary for writing robust server software.
  *
- * Copyright (c) 2010 Phusion
+ * Copyright (c) 2010, 2011, 2012 Phusion
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -32,6 +32,10 @@
  * so often by application programmers.
  */
 
+#define OXT_GCC_VERSION (__GNUC__ * 10000 \
+                           + __GNUC_MINOR__ * 100 \
+                           + __GNUC_PATCHLEVEL__)
+
 #if (defined(__GNUC__) && (__GNUC__ > 2) && !defined(OXT_DEBUG)) || defined(IN_DOXYGEN)
 	/**
 	 * Indicate that the given expression is likely to be true.
@@ -55,4 +59,31 @@
 	#define OXT_UNLIKELY(expr) expr
 #endif
 
+/*
+ * GCC supports the __thread keyword on x86 since version 3.3, but versions earlier
+ * than 4.1.2 have bugs (http://gcc.gnu.org/ml/gcc-bugs/2006-09/msg02275.html).
+ *
+ * FreeBSD 5 supports the __thread keyword, and everything works fine in
+ * micro-tests, but in mod_passenger the thread-local variables are initialized
+ * to unaligned addresses for some weird reason, thereby causing bus errors.
+ *
+ * GCC on OpenBSD supports __thread, but any access to such a variable
+ * results in a segfault.
+ *
+ * Solaris does support __thread, but often it's not compiled into default GCC 
+ * packages (not to mention it's not available for Sparc). Playing it safe...
+ *
+ * On MacOS X, neither gcc nor llvm-gcc support the __thread keyword, but Clang
+ * does. It works on at least clang >= 3.0.
+ */
+#if defined(__APPLE__)
+	#if defined(__clang__) && __clang_major__ >= 3
+		#define OXT_THREAD_LOCAL_KEYWORD_SUPPORTED
+	#endif
+#elif defined(__GNUC__) && OXT_GCC_VERSION >= 40102
+	#if !defined(__SOLARIS__) && !defined(__OpenBSD__)
+		#define OXT_THREAD_LOCAL_KEYWORD_SUPPORTED
+	#endif
+#endif
+
 #endif /* _OXT_MACROS_HPP_ */
diff --git a/ext/oxt/spin_lock.hpp b/ext/oxt/spin_lock.hpp
@@ -25,6 +25,8 @@
 #ifndef _OXT_SPIN_LOCK_HPP_
 #define _OXT_SPIN_LOCK_HPP_
 
+#include "macros.hpp"
+
 // At the time of writing (July 22, 2008), these operating systems don't
 // support pthread spin locks:
 // - OpenBSD 4.3
@@ -34,12 +36,6 @@
 	#define OXT_NO_PTHREAD_SPINLOCKS
 #endif
 
-#ifndef OXT_GCC_VERSION
-	#define OXT_GCC_VERSION (__GNUC__ * 10000 \
-	                     + __GNUC_MINOR__ * 100 \
-	                     + __GNUC_PATCH_LEVEL__)
-#endif
-
 #if defined(__APPLE__)
 	#include "detail/spin_lock_darwin.hpp"
 #elif (OXT_GCC_VERSION > 40100 && (defined(__i386__) || defined(__x86_64__))) || defined(IN_DOXYGEN)