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RE: Optimization of conditional access to globals: thread-unsafe?
On 22 October 2007 18:34, Andrew Haley wrote:
> > Again, we are not discussing some particular code sample, and how it
> > might be fixed, but the problem in general. Should GCC do
> > thread-unsafe optimizations, or not?
> We do understand what you're saying, and simply repeating the same
> thing doesn't help.
Well, just to answer the question at face value, "Yes, of course it should,
because 99.9% of the time the fact of their thread-safety or otherwise is
The interesting question of course is how we can get the compiler to
recognize that 0.1% when thread-safety is not just relevant but vital. That
may still end up requiring some kind of annotation (like 'volatile'), but
defining a clear memory model should allow the compiler to make inferences and
deductions for itself that save the programmer a lot of the work of specifying
what data needs to be thread-safe and when and where.
Can't think of a witty .sigline today....