1 files changed, 61 insertions, 0 deletions
diff --git a/sysdeps/aarch64/fpu/tanhf_sve.c b/sysdeps/aarch64/fpu/tanhf_sve.c
new file mode 100644
index 0000000000..0b94523cf5
--- /dev/null
+++ b/sysdeps/aarch64/fpu/tanhf_sve.c
@@ -0,0 +1,61 @@
+/* Single-precision vector (SVE) tanh function
+
+   Copyright (C) 2024 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 "sv_expm1f_inline.h"
+
+static const struct data
+{
+  struct sv_expm1f_data expm1f_consts;
+  uint32_t boring_bound, onef;
+} data = {
+  .expm1f_consts = SV_EXPM1F_DATA,
+  /* 0x1.205966p+3, above which tanhf rounds to 1 (or -1 for negative).  */
+  .boring_bound = 0x41102cb3,
+  .onef = 0x3f800000,
+};
+
+static svfloat32_t NOINLINE
+special_case (svfloat32_t x, svfloat32_t y, svbool_t special)
+{
+  return sv_call_f32 (tanhf, x, y, special);
+}
+
+/* Approximation for single-precision SVE tanh(x), using a simplified
+   version of expm1f. The maximum error is 2.57 ULP:
+   _ZGVsMxv_tanhf (0x1.fc1832p-5) got 0x1.fb71a4p-5
+				 want 0x1.fb71aap-5.  */
+svfloat32_t SV_NAME_F1 (tanh) (svfloat32_t x, const svbool_t pg)
+{
+  const struct data *d = ptr_barrier (&data);
+
+  svfloat32_t ax = svabs_x (pg, x);
+  svuint32_t iax = svreinterpret_u32 (ax);
+  svuint32_t sign = sveor_x (pg, svreinterpret_u32 (x), iax);
+  svbool_t is_boring = svcmpgt (pg, iax, d->boring_bound);
+  svfloat32_t boring = svreinterpret_f32 (svorr_x (pg, sign, d->onef));
+
+  svbool_t special = svcmpgt (pg, iax, 0x7f800000);
+
+  /* tanh(x) = (e^2x - 1) / (e^2x + 1).  */
+  svfloat32_t q = expm1f_inline (svmul_x (pg, x, 2.0), pg, &d->expm1f_consts);
+  svfloat32_t y = svdiv_x (pg, q, svadd_x (pg, q, 2.0));
+  if (__glibc_unlikely (svptest_any (pg, special)))
+    return special_case (x, svsel_f32 (is_boring, boring, y), special);
+  return svsel_f32 (is_boring, boring, y);
+}