Bug 27344

Gillen, thanks for the report. I will try to remember to look over which pathways are missing the INITIALIZER.

However, do you mind investing why you need the atomic mutex in the first place? i.e. how we are not detecting or have chosen the correct atomics ops for windows. [There is a massive performance cost in using the mutex based fallbacks instead of atomic ops.]

Well I build cairo with my own build system, so I could have missed an important configuration step. But if I understand the code correctly there are only 2 implementations of atomic ops: The Intel atomic ops which don't work with the Microsoft compiler and the atomic_ops library which I currently don't have installed. Is there another one which I am missing?

Oh well. I have memories of at least the Intel mmx/sse[123] intrinics being available for MSVC, or at least something approaching interoperability. For someone knowledgeable in the Win32 APIs I am sure that adding the equivalent wouldn't be too challenging. InterleavedLockExchange() and friends, IIRC.

Created attachment 34513 [details] [review]
Win32 atomic ops

Well here is a patch that implements the needed defines with winapi functions. It works for my very simple usecase, but I haven't tested it further. If you want to use atomic ops, cairo also needs the ffs function which doesn't exist in MSVC. The following code can replace it:

int ffs(int mask) 
{
	unsigned long index;
	if (_BitScanForward(&index, mask) == 0)
		return 0;
	else
		return index + 1;
}

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