<div dir="ltr">This change was reverted in r211072 due to accidentally pushing a whole branch instead of a single CL.<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jun 16, 2014 at 3:39 PM, Zachary Turner <span dir="ltr"><<a href="mailto:zturner@google.com" target="_blank">zturner@google.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: zturner<br>
Date: Mon Jun 16 17:39:38 2014<br>
New Revision: 211066<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=211066&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=211066&view=rev</a><br>
Log:<br>
Users of the llvm global mutex must now acquire it manually.<br>
<br>
This allows the mutex to be acquired in a guarded, RAII fashion.<br>
<br>
Modified:<br>
    llvm/trunk/include/llvm/Support/Mutex.h<br>
    llvm/trunk/include/llvm/Support/Threading.h<br>
    llvm/trunk/lib/Support/ManagedStatic.cpp<br>
    llvm/trunk/lib/Support/Threading.cpp<br>
    llvm/trunk/lib/Support/Timer.cpp<br>
<br>
Modified: llvm/trunk/include/llvm/Support/Mutex.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Mutex.h?rev=211066&r1=211065&r2=211066&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Mutex.h?rev=211066&r1=211065&r2=211066&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/include/llvm/Support/Mutex.h (original)<br>
+++ llvm/trunk/include/llvm/Support/Mutex.h Mon Jun 16 17:39:38 2014<br>
@@ -15,11 +15,13 @@<br>
 #define LLVM_SUPPORT_MUTEX_H<br>
<br>
 #include "llvm/Support/Compiler.h"<br>
-#include "llvm/Support/Threading.h"<br>
 #include <cassert><br>
<br>
 namespace llvm<br>
 {<br>
+  // Forward declare.<br>
+  bool llvm_is_multithreaded();<br>
+<br>
   namespace sys<br>
   {<br>
     /// @brief Platform agnostic Mutex class.<br>
<br>
Modified: llvm/trunk/include/llvm/Support/Threading.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Threading.h?rev=211066&r1=211065&r2=211066&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Threading.h?rev=211066&r1=211065&r2=211066&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/include/llvm/Support/Threading.h (original)<br>
+++ llvm/trunk/include/llvm/Support/Threading.h Mon Jun 16 17:39:38 2014<br>
@@ -14,7 +14,12 @@<br>
 #ifndef LLVM_SUPPORT_THREADING_H<br>
 #define LLVM_SUPPORT_THREADING_H<br>
<br>
+#include "llvm/Support/Mutex.h"<br>
+<br>
 namespace llvm {<br>
+  /// llvm_get_global_lock - returns the llvm global lock object.<br>
+  sys::Mutex& llvm_get_global_lock();<br>
+<br>
   /// llvm_start_multithreaded - Allocate and initialize structures needed to<br>
   /// make LLVM safe for multithreading.  The return value indicates whether<br>
   /// multithreaded initialization succeeded.  LLVM will still be operational<br>
@@ -33,14 +38,6 @@ namespace llvm {<br>
   /// mode or not.<br>
   bool llvm_is_multithreaded();<br>
<br>
-  /// acquire_global_lock - Acquire the global lock.  This is a no-op if called<br>
-  /// before llvm_start_multithreaded().<br>
-  void llvm_acquire_global_lock();<br>
-<br>
-  /// release_global_lock - Release the global lock.  This is a no-op if called<br>
-  /// before llvm_start_multithreaded().<br>
-  void llvm_release_global_lock();<br>
-<br>
   /// llvm_execute_on_thread - Execute the given \p UserFn on a separate<br>
   /// thread, passing it the provided \p UserData.<br>
   ///<br>
<br>
Modified: llvm/trunk/lib/Support/ManagedStatic.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/ManagedStatic.cpp?rev=211066&r1=211065&r2=211066&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/ManagedStatic.cpp?rev=211066&r1=211065&r2=211066&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/lib/Support/ManagedStatic.cpp (original)<br>
+++ llvm/trunk/lib/Support/ManagedStatic.cpp Mon Jun 16 17:39:38 2014<br>
@@ -14,6 +14,7 @@<br>
 #include "llvm/Support/ManagedStatic.h"<br>
 #include "llvm/Config/config.h"<br>
 #include "llvm/Support/Atomic.h"<br>
+#include "llvm/Support/MutexGuard.h"<br>
 #include <cassert><br>
 using namespace llvm;<br>
<br>
@@ -23,7 +24,7 @@ void ManagedStaticBase::RegisterManagedS<br>
                                               void (*Deleter)(void*)) const {<br>
   assert(Creator);<br>
   if (llvm_is_multithreaded()) {<br>
-    llvm_acquire_global_lock();<br>
+    llvm::MutexGuard Lock(llvm::llvm_get_global_lock());<br>
<br>
     if (!Ptr) {<br>
       void* tmp = Creator();<br>
@@ -43,8 +44,6 @@ void ManagedStaticBase::RegisterManagedS<br>
       Next = StaticList;<br>
       StaticList = this;<br>
     }<br>
-<br>
-    llvm_release_global_lock();<br>
   } else {<br>
     assert(!Ptr && !DeleterFn && !Next &&<br>
            "Partially initialized ManagedStatic!?");<br>
<br>
Modified: llvm/trunk/lib/Support/Threading.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Threading.cpp?rev=211066&r1=211065&r2=211066&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Threading.cpp?rev=211066&r1=211065&r2=211066&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/lib/Support/Threading.cpp (original)<br>
+++ llvm/trunk/lib/Support/Threading.cpp Mon Jun 16 17:39:38 2014<br>
@@ -21,13 +21,15 @@ using namespace llvm;<br>
<br>
 static bool multithreaded_mode = false;<br>
<br>
-static sys::Mutex* global_lock = nullptr;<br>
+sys::Mutex& llvm::llvm_get_global_lock() {<br>
+  static sys::Mutex global_lock;<br>
+  return global_lock;<br>
+}<br>
<br>
 bool llvm::llvm_start_multithreaded() {<br>
 #if LLVM_ENABLE_THREADS != 0<br>
   assert(!multithreaded_mode && "Already multithreaded!");<br>
   multithreaded_mode = true;<br>
-  global_lock = new sys::Mutex(true);<br>
<br>
   // We fence here to ensure that all initialization is complete BEFORE we<br>
   // return from llvm_start_multithreaded().<br>
@@ -47,7 +49,6 @@ void llvm::llvm_stop_multithreaded() {<br>
   sys::MemoryFence();<br>
<br>
   multithreaded_mode = false;<br>
-  delete global_lock;<br>
 #endif<br>
 }<br>
<br>
@@ -55,14 +56,6 @@ bool llvm::llvm_is_multithreaded() {<br>
   return multithreaded_mode;<br>
 }<br>
<br>
-void llvm::llvm_acquire_global_lock() {<br>
-  if (multithreaded_mode) global_lock->acquire();<br>
-}<br>
-<br>
-void llvm::llvm_release_global_lock() {<br>
-  if (multithreaded_mode) global_lock->release();<br>
-}<br>
-<br>
 #if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)<br>
 #include <pthread.h><br>
<br>
<br>
Modified: llvm/trunk/lib/Support/Timer.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Timer.cpp?rev=211066&r1=211065&r2=211066&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Timer.cpp?rev=211066&r1=211065&r2=211066&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/lib/Support/Timer.cpp (original)<br>
+++ llvm/trunk/lib/Support/Timer.cpp Mon Jun 16 17:39:38 2014<br>
@@ -18,7 +18,7 @@<br>
 #include "llvm/Support/FileSystem.h"<br>
 #include "llvm/Support/Format.h"<br>
 #include "llvm/Support/ManagedStatic.h"<br>
-#include "llvm/Support/Mutex.h"<br>
+#include "llvm/support/MutexGuard.h"<br>
 #include "llvm/Support/Process.h"<br>
 #include "llvm/Support/raw_ostream.h"<br>
 using namespace llvm;<br>
@@ -84,14 +84,13 @@ static TimerGroup *getDefaultTimerGroup(<br>
   sys::MemoryFence();<br>
   if (tmp) return tmp;<br>
<br>
-  llvm_acquire_global_lock();<br>
+  llvm::MutexGuard Lock(llvm::llvm_get_global_lock());<br>
   tmp = DefaultTimerGroup;<br>
   if (!tmp) {<br>
     tmp = new TimerGroup("Miscellaneous Ungrouped Timers");<br>
     sys::MemoryFence();<br>
     DefaultTimerGroup = tmp;<br>
   }<br>
-  llvm_release_global_lock();<br>
<br>
   return tmp;<br>
 }<br>
<br>
<br>
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</blockquote></div><br></div>