On Feb 8, 2008, at 10:03 AM, Duncan Sands wrote: > I can't help feeling that a bitfield load or store should touch the > minimum amount of bytes possible: only those that contain some part > of the bitfield. In some situations touching other bytes could be > fatal, for example if the type is overlaid on some memory mapped io > region, or multiple threads are accessing different parts of the > type simulteneously.
I do not think this is required as part of current C ABI. This is responsibility of programmer who is using threading. > In the above example you could try accessing > d using 4 bytes starting from b, but this would give wrong results > if some other thread was accessing b at the same time. I'm fairly > sure that Ada has quite strict requirements about this, and I have > the vague idea (I don't know where I got it from) that there is talk > of requiring a minimum disturbance rule of some kind in C. However what about huge amount of existing C code and other tools that do not enforce this ? - Devang _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
