https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101456
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Arjan van de Ven from comment #1)
> Actually it's not that they're zero (they are) but they're in "init" state
> since the vpxor wrote to xmm not ymm
We generate:
vxorpd %xmm0, %xmm0, %xmm0 # 5 [c=4 l=4] movv4df_internal/0
to zero all bits in YMM and ZMM registers.
