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SwapSwapPosted Apr 2, 2013 9:17 UTC (Tue) by tialaramex (subscriber, #21167)In reply to: Swap by proski Parent article: A look at C++14: Papers Part 2
I can imagine that there might be platforms on which (especially for larger or more sophisticated native C types like doubles) atomic swap is not practical.
So perhaps C could consider offering swap with no promises of atomicity, plus a set of reserved pre-processor variables which tell us whether atomicity is implemented for specific types. This would let you do
#if !defined(SWAP_UINT64_T_IS_ATOMIC)
... or something more useful, but you get the idea.
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Swap Posted Apr 2, 2013 20:12 UTC (Tue) by scottwood (subscriber, #74349) [Link]
If non-atomic swap is a useful addition, why would you want to slow down swaps that don't need to be atomic by making it automatic, even if it's optional for the implementation? Atomic swap should be a specially requested operation (e.g. using compiler intrinsics), just like most other atomic operations.
Swap Posted Apr 3, 2013 5:05 UTC (Wed) by Ben_P (subscriber, #74247) [Link]
Atomic swaps on doubles (and floats) are made more tricky by the fact very often NaN != NaN.
Swap Posted Apr 5, 2013 23:18 UTC (Fri) by mathstuf (subscriber, #69389) [Link]
Can't you just treat them as integers of the same size for CAS?
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