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, 88 insertions, 0 deletions

diff --git a/benchtests/bench-libmvec-skeleton.c b/benchtests/bench-libmvec-skeleton.c
new file mode 100644
index 0000000000..7fa96cabb7
--- /dev/null
+++ b/benchtests/bench-libmvec-skeleton.c
@@ -0,0 +1,88 @@
+/* Skeleton for libmvec benchmark programs.
+   Copyright (C) 2021-2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <time.h>
+#include <inttypes.h>
+#include <bench-timing.h>
+#include <json-lib.h>
+#include <bench-util.h>
+#include <math-tests-arch.h>
+#include <bench-libmvec-arch.h>
+
+#include <bench-util.c>
+#define D_ITERS 10000
+
+int
+main (int argc, char **argv)
+{
+  unsigned long i, k;
+  timing_t start, end;
+  json_ctx_t json_ctx;
+
+#ifdef INIT_ARCH
+  INIT_ARCH ();
+#endif
+
+  bench_start ();
+
+#ifdef BENCH_INIT
+  BENCH_INIT ();
+#endif
+
+  json_init (&json_ctx, 2, stdout);
+
+  /* Begin function.  */
+  json_attr_object_begin (&json_ctx, FUNCNAME);
+
+  for (int v = 0; v < NUM_VARIANTS; v++)
+    {
+      double d_total_time = 0;
+      timing_t cur;
+      for (k = 0; k < D_ITERS; k++)
+	{
+	  TIMING_NOW (start);
+	  for (i = 0; i < NUM_SAMPLES (v); i++)
+	    BENCH_FUNC (v, i);
+	  TIMING_NOW (end);
+
+	  TIMING_DIFF (cur, start, end);
+
+	  TIMING_ACCUM (d_total_time, cur);
+	}
+      double d_total_data_set = D_ITERS * NUM_SAMPLES (v) * STRIDE;
+
+      /* Begin variant.  */
+      json_attr_object_begin (&json_ctx, VARIANT (v));
+
+      json_attr_double (&json_ctx, "duration", d_total_time);
+      json_attr_double (&json_ctx, "iterations", d_total_data_set);
+      json_attr_double (&json_ctx, "mean", d_total_time / d_total_data_set);
+
+      /* End variant.  */
+      json_attr_object_end (&json_ctx);
+    }
+
+  /* End function.  */
+  json_attr_object_end (&json_ctx);
+
+  return 0;
+}