Richard Henderson <[EMAIL PROTECTED]> writes: > Not all targets are going to be able to implement the builtins, > even with locks. It is imperitive that the target have an > atomic store operation, so that other read-only references to > the variable see either the old or new value, but not a mix.
How many processors out there support multi-processor systems but do not provide any sort of atomic store operation? On a uni-processor system, presumably we only have to worry about preemptive thread switching and signals. Appropriate locking mechanisms are available for both. I can see that there is a troubling case that code may be compiled for i386 and then run on a multi-processing system using newer processors. That is something which we would have to detect at run time, in start up code or the first time the builtins are invoked. But it's not like I've looked at this stuff all that much. In general, what is the worst case we have to worry about? Ian
