> 17:24:53 < derf> They reset the rounding modes on entrance and exit of expf(), for example, regardless of whether or not they're already correctly set up.

I fixed this around the same time I worked on the mp improvements:

commit 2506109403de69bd454de27835d42e6eb6ec3abc Author: Siddhesh Poyarekar <[email protected]> Date: Wed Jun 12 10:36:48 2013 +0530

    Set/restore rounding mode only when needed
    
    The most common use case of math functions is with default rounding
    mode, i.e. rounding to nearest.  Setting and restoring rounding mode
    is an unnecessary overhead for this, so I've added support for a
    context, which does the set/restore only if the FP status needs a
    change.  The code is written such that only x86 uses these.  Other
    architectures should be unaffected by it, but would definitely benefit
    if the set/restore has as much overhead relative to the rest of the
    code, as the x86 bits do.