Question
Extended (80-bit) double floating point in x87, not SSE2 - we don't miss it?
I was reading today about researchers discovering that NVidia's Phys-X libraries use x87 FP vs. SSE2. Obviously this will be suboptimal for parallel datasets where speed trumps precision. However, the article author goes on to quote:
Intel started discouraging the use of x87 with the introduction of the P4 in late 2000. AMD deprecated x87 since the K8 in 2003, as x86-64 is defined with SSE2 support; VIA’s C7 has supported SSE2 since 2005. In 64-bit versions of Windows, x87 is deprecated for user-mode, and prohibited entirely in kernel-mode. Pretty much everyone in the industry has recommended SSE over x87 since 2005 and there are no reasons to use x87, unless software has to run on an embedded Pentium or 486.
I wondered about this. I know that x87 uses 80-bit extended doubles internally to compute values, and SSE2 doesn't. Does this not matter to anyone? It seems surprising to me. I know when I do computations on points, lines and polygons in a plane, values can be surprisingly wrong when doing subtractions, and areas can collapse and lines alias one another due to lack of precision. Using 80-bit values vs. 64-bit values could help, I would imagine.
Is this incorrect? If not, what can we use to perform extended double FP operations if x87 is phased out?