commit e72dfeb8b9fa5662831b5d0bb9d132521f9173dd
author Antonio Sanchez <cantonios@google.com> Wed Mar 03 09:41:46 2021 -0800
committer Antonio Sanchez <cantonios@google.com> Wed Mar 03 09:41:46 2021 -0800
tree bdc7a7bd7f8fa13a65bd71897282bcc4e3bc87d5
parent 199c5f2b47eb1f8e5a2d20e60f07e97cd95a6ba6

Fix rint for SSE/NEON.

It seems *sometimes* with aggressive optimizations the combination
`psub(padd(a, b), b)` trick to force rounding is compiled away. Here
we replace with inline assembly to prevent this (I tried `volatile`,
but that leads to additional loads from memory).

Also fixed an edge case for large inputs `a` where adding `b` bumps
the value up a power of two and ends up rounding away more than
just the fractional part.  If we are over `2^digits` then just return
the input.  This edge case was missed in the test since the test was
comparing approximate equality, which was still satisfied.  Adding
a strict equality option catches it.