https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110105
--- Comment #4 from Pavel M <pavel.morozkin at gmail dot com> ---
To: rsand...@gcc.gnu.org
Thanks! I confused __fp16 with _Float16.
However, if __fp16 is only a “storage type”, then why this code:
__fp16 mul(__fp16 x, __fp16 y)
{
return x * y;
}
compiled with -O3 -mfpu=fp-armv8 -march=armv8.2-a+fp16
leads to this code:
mul:
vmul.f16 s0, s0, s1
bx lr
Here we see vmul.f16 instead of half->float->vmul.f32->float->half.
As a user, I expect half->float->vmul.f32->float->half (because __fp16 is only
a “storage type”).
Where is the conversions and mul.f32?
P.S. If optimizer does this, then as I remember, half->float->op->float->half
does not always produce the same result as half->op->half. The difference in
result may be +/-1 (last) bit. Any comments?
