"InterlockedExchangeAdd(p, x) + x" works exactly the same as " __sync_add_and_fetch(p, x)", no need to use asm.
On Wed, Jul 1, 2015 at 9:53 AM, Bastien Montagne <[email protected]> wrote: > So, trying to hunt an strange issue with Windows scons builds of > filebrowser work, I found that our attomic operations (defined in > intern/atomic/atomci_ops.h) do not return the same things on MSVC than > with other OS/compilers. > > With GCC & co we use `__sync_add_and_fetch`, on OSX, `OSAtomicAdd64`, > with MSVC `InterlockedExchangeAdd64`, and have a fallback implementation > in plain assembler. > > According to documentations (and my limited asm understanding), MSVC > version returns the value of `*p` *before* the operation, while all > others return it *after* the operation (i.e. return the result of the > operation). > > https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gcc/_005f_005fsync-Builtins.html > https://msdn.microsoft.com/en-us/library/windows/desktop/ms683599(v=vs.85).aspx > https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man3/OSAtomicAdd64.3.html > > I doubt this is desired behavior, and think it could easily generate > nasty bug some day… MSVC does not seem to have a 'return value after > operation' variant from quick look at the doc? Maybe we should just > remove the MSVC case completely and use asm version instead? > > Bastien > _______________________________________________ > Bf-committers mailing list > [email protected] > http://lists.blender.org/mailman/listinfo/bf-committers _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers
