The perennial i386 floating-point rounding issue...

[Zack Weinberg]

I believe I saw this go by again just a few days back, but I can't
find it anymore.  Anyhow, while digging through C99 for something else
I found this paragraph:

5.1.2.3p12 
  EXAMPLE 4 Implementations employing wide registers have to take care
  to honor appropriate semantics.  Values are independent of whether
  they are represented in a register or in memory. For example, an
  implicit spilling of a register is not permitted to alter the value.

This sure sounds like we are required to do 80-bit spills, if we use
the extended precision mode.

zw