[Lldb-commits] [PATCH] D13940: Fix race conditions in Core/Timer

[Greg Clayton via lldb-commits]

clayborg requested changes to this revision.
clayborg added a comment.
This revision now requires changes to proceed.

"thread_local" isn't well supported and has performance issues. See inlined comments.


================
Comment at: include/lldb/Core/Timer.h:89
@@ +88,3 @@
+
+    static thread_local unsigned g_depth;
+
----------------
Not sure if all platforms support thread_local correctly. MacOSX might not. I also spoke with some compiler folks on using "thread_local" and they warned that the C++11 spec requires a bunch of other stuff gets initialized when _any_ thread_local variable gets used, so I was told that using the "__thread" instead of much better to do. So switch this from thread_local to __thread and it should work on most platforms. Not sure if windows will have a problem with this. 

So the best fix is probably to make a LLDB_THREAD_LOCAL #define in lldb-defines.h and define it to "__thread" by default. Windows can fix up as needed.

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Comment at: source/Core/Timer.cpp:27
@@ +26,3 @@
+
+thread_local unsigned Timer::g_depth(0);
+
----------------
Use LLDB_THREAD_LOCAL instead of "thread_local".


http://reviews.llvm.org/D13940