[racket-dev] Extflonum type for windows

From: Neil Toronto (neil.toronto at gmail.com)
Date: Wed Mar 20 18:39:17 EDT 2013

On 03/20/2013 05:14 AM, Michael Filonenko wrote:
>> Meanwhile, it happens that switching the precision at the last minute
>> allows the 32-bit Windows build to support extflonums without using SSE
>> and without affecting flonum arithmetic.
> Agreed. But since switching the processor "at last minute" every time
> slows things down a bit, it may be useful to have an option to
> switch to the extended mode on Win32 just once. That will be useful
> for us and other users who have SSE and worry about performance.
> Could you please take a look on the updated pull request which now
> contains #define-guarded code?

I expect this to cause the tests in "math/tests/flonum-tests.rkt" to fail.

I think the optimization Matthew mentioned earlier - switching to 
extended mode once for multiple operations - is a better option. The 
blocks of code guarded by mode switches should be roughly the same as 
those that stack-allocate extflonums. IOW, switching modes would mostly 
coincide with moving extflonums in and out of the heap, which is slow 
enough that the mode switches would be unnoticeable.

Neil ⊥

Posted on the dev mailing list.