On 8/4/2016 7:08 AM, Andrew Godfrey wrote:
Now, my major experience is in the context of Intel non-SIMD FP, where internal precision is 80-bit. I can see the appeal of asking for the ability to reduce internal precision to match the data type you're using, and I think I've read something written by Walter on that topic. But this would hardly be "C-like" FP support so I'm not sure that's he topic at hand.
Also, carefully reading the C Standard, D's behavior is allowed by the C Standard. The idea that C requires rounding of all intermediate values to the target precision is incorrect, and is not "C-like". C floating point semantics can and do vary from platform to platform, and vary based on optimization settings, and this is all allowed by the C Standard.
It has been proposed many times that the solution for D is to have a function called toFloat() or something like that in core.math, which guarantees a round to float precision for its argument. But so far nobody has written such a function.
