On Thu, Jun 9, 2022 at 2:17 PM Stanislaw Kardach <k...@semihalf.com> wrote:
As David noticed in [1] there is an issue with C++ compilation of the
rte_vect.h header in RISC-V. Upon closer inspection, the problem appears on
all architectures due to the type conversion rules in C++.
More precisely a union type rte_xmm_t requires a conversion constructor
from xmm_t type.
The most obvious fix is to use a structure initializer for such copies
(since rte_xmm_t union contains xmm_t anyway). The generated assembly
at -O2 is exactly the same, so there's no real impact.
The bigger question is whether accessing bits of the architecture specific
xmm_t type in an array fashion is always correct? All current architectures
define rte_xmm_t in the same manner implying that.
Copying other arch maintainers.
My read of the Altivec vector layout for LE systems says the existing
union operator rte_xmm_t is correct, though my C++ experience is
limited. How can I generate an error with C++ to expose this issue?
Dave
