[PATCH 0/3] ARM with only 32-bit floats do not have fast 64-bit FMA

[Sebastian Huber]

On 02/09/2020 19:12, Joseph Myers wrote:

> On Wed, 2 Sep 2020, Sebastian Huber wrote:
>
>> https://sourceware.org/git/?p=glibc.git;a=blob;f=math/s_fma.c;h=4d73af4f65d511594b2395d032a135721c578484;hb=HEAD
> No glibc configurations use that; they all use either a hardware
> instruction, an implementation based on sticky rounding as described by
> Boldo and Melquiond, or, in the absence of hardware exceptions and
> rounding modes, a soft-fp implementation.

Sorry for pointing to this dead code in glibc.

Maybe we can use the FreeBSD implementation:

https://github.com/freebsd/freebsd/blob/master/lib/msun/src/s_fma.c

It is probably also used by Bionic:

https://android.googlesource.com/platform/bionic/+/refs/heads/master/libm/upstream-freebsd/lib/msun/src/s_fma.c