Enable libmvec support for AArch64

This patch enables libmvec on AArch64. The proposed change is mainly
implementing build infrastructure to add the new routines to ABI,
tests and benchmarks. I have demonstrated how this all fits together
by adding implementations for vector cos, in both single and double
precision, targeting both Advanced SIMD and SVE.

The implementations of the routines themselves are just loops over the
scalar routine from libm for now, as we are more concerned with
getting the plumbing right at this point. We plan to contribute vector
routines from the Arm Optimized Routines repo that are compliant with
requirements described in the libmvec wiki.

Building libmvec requires minimum GCC 10 for SVE ACLE. To avoid raising
the minimum GCC by such a big jump, we allow users to disable libmvec
if their compiler is too old.

Note that at this point users have to manually call the vector math
functions. This seems to be acceptable to some downstream users.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 054d81fc81..a52c17c677 100644
--- a/NEWS
+++ b/NEWS
@@ -29,6 +29,12 @@ Major new features:
 
     - x86_64-gnu
 
+* Added libmvec vector math library support to AArch64.  It requires
+  GCC version >= 10.1.0.  It can be disabled via --disable-mathvec,
+  however that is not a supported configuration as it changes the ABI.
+  The symbol names follow the AArch64 vector ABI, they are declared
+  in math.h and have to be called manually at this point.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * In the Linux kernel for the hppa/parisc architecture some of the