[llvm-commits] [llvm] r116489 - /llvm/trunk/include/llvm/PassSupport.h

[Jakob Stoklund Olesen]

On Oct 14, 2010, at 10:26 AM, Owen Anderson wrote:

> Author: resistor
> Date: Thu Oct 14 12:26:06 2010
> New Revision: 116489
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=116489&view=rev
> Log:
> Apparently MSVC doesn't support thread-safe static local initialization.  Roll our own solution instead.

>   void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
> +    static sys::cas_flag initialized = 0; \
> +    sys::cas_flag old_val = sys::CompareAndSwap(&initialized, 1, 0); \
> +    if (old_val == 0) initialize##passName##PassOnce(Registry); \
> +  }

Hi Owen,

AFAICT, this guarantees that initialize*PassOnce is called only once, but it doesn't guarantee that initialize*PassOnce has completed when initialize*Pass returns.

Wouldn't threads expect initialization to be complete after initialize*Pass returns?

/jakob