[cfe-dev] __thread keyword, LLVM 3.2 & Xcode 4.6

Jean-Daniel Dupas devlists at shadowlab.org
Tue Nov 6 01:04:02 PST 2012

Le 6 nov. 2012 à 01:37, James Gregurich <bayoubengal at me.com> a écrit :

> hi.
> I just updated to Xcode 4.6.  I note the following:
> $ /Applications/Xcode46-DP1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang --version
> Apple clang version 4.2 (tags/Apple/clang-424.0.11) (based on LLVM 3.2svn)
> Target: x86_64-apple-darwin12.2.0
> Thread model: posix
> It is my understanding from the release notes, that LLVM 3.2 is support thread-local storage. I just re-ran my test using the '__thread' keyword from the last time I asked about this and I still just get one instance of the object rather than one-per-thread.

The __thread keyword is a C extension (it not part of the standard). Using it with C++ as is even less specified than using it with C.

Moreover, it has already be specified in the previous discussion that supporting C++ TLS required OS support. Updating Xcode does not change that. 

-- Jean-Daniel

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