[Bug libgcc/59714] complex division is surprising on aarch64

[michael.hudson at linaro dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59714

--- Comment #4 from Michael Hudson-Doyle <michael.hudson at linaro dot org> ---
OK, so I should stop talking about accurate and instead talk about surprising
:-)

I think it is pretty surprising that x/x != 1+0i for (I think) all x where the
ratio between the real and imaginary parts is not a power of 2 (put another
way, an error of 1ulp when the accurate result is 0 is more surprising than
when the accurate result is non-zero).

In general, fma makes it hard to reason about expressions like "a*b-c*d" --
which of the multiplications is being done at the higher precision?  But I
guess arguing to fp-contract to default to off is a war I don't want to get
into fighting.