On 26/02/2019 20:44, Nick Desaulniers wrote:
On Mon, Feb 25, 2019 at 11:19 PM Ard Biesheuvel
<ard.biesheu...@linaro.org> wrote:
On Tue, 26 Feb 2019 at 05:03, <ndesaulni...@google.com> wrote:
Clang warns: vector initializers are not compatible with NEON intrinsics
in big endian mode [-Wnonportable-vector-initialization]
While this is usually the case, it's not an issue for this case since
we're initializing the uint8x16_t (16x uint8_t's) with the same value.
Instead, use vdupq_n_u8 which both compilers lower into a single movi
instruction: https://godbolt.org/z/vBrgzt
This avoids the static storage for a constant value.
Link: https://github.com/ClangBuiltLinux/linux/issues/214
Suggested-by: Nathan Chancellor <natechancel...@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
Much better, thanks,
Did you double check that the intrinsic exists on 32-bit ARM as well?
I assume it does, but please make sure if you haven't yet.
Thanks for the review!
Looking through Clang's generated arm_neon.h, vdupq_n_u8 seems to have
2 definitions predicated on __LITTLE_ENDIAN__ (not __arch64__ or
__ARM_ARCH >= 8 like some of the other types and functions).
So NEON got some additions in v8? Is there a doc that lists them?
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0491g/BABDBBJB.html
is where I found vdupq_n_u8, but it doesn't seem to mention
compatibility (so I assume it's been around since the introduction of
NEON?).
FWIW the most recent 'proper' spec document I know of is this one:
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0073b/index.html
Apparently we have a more interactive playground on the new site, too:
https://developer.arm.com/technologies/neon/intrinsics
Robin.