1 files changed, 50 insertions, 0 deletions
diff --git a/pl/math/sv_acosh_3u5.c b/pl/math/sv_acosh_3u5.c
new file mode 100644
index 000000000000..faf351331464
--- /dev/null
+++ b/pl/math/sv_acosh_3u5.c
@@ -0,0 +1,50 @@
+/*
+ * Double-precision SVE acosh(x) function.
+ * Copyright (c) 2023, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#include "sv_math.h"
+#include "pl_sig.h"
+#include "pl_test.h"
+
+#define WANT_SV_LOG1P_K0_SHORTCUT 1
+#include "sv_log1p_inline.h"
+
+#define BigBoundTop 0x5fe /* top12 (asuint64 (0x1p511)).  */
+#define OneTop 0x3ff
+
+static NOINLINE svfloat64_t
+special_case (svfloat64_t x, svfloat64_t y, svbool_t special)
+{
+  return sv_call_f64 (acosh, x, y, special);
+}
+
+/* SVE approximation for double-precision acosh, based on log1p.
+   The largest observed error is 3.19 ULP in the region where the
+   argument to log1p falls in the k=0 interval, i.e. x close to 1:
+   SV_NAME_D1 (acosh)(0x1.1e4388d4ca821p+0) got 0x1.ed23399f5137p-2
+					   want 0x1.ed23399f51373p-2.  */
+svfloat64_t SV_NAME_D1 (acosh) (svfloat64_t x, const svbool_t pg)
+{
+  svuint64_t itop = svlsr_x (pg, svreinterpret_u64 (x), 52);
+  /* (itop - OneTop) >= (BigBoundTop - OneTop).  */
+  svbool_t special = svcmpge (pg, svsub_x (pg, itop, OneTop), sv_u64 (0x1ff));
+
+  svfloat64_t xm1 = svsub_x (pg, x, 1);
+  svfloat64_t u = svmul_x (pg, xm1, svadd_x (pg, x, 1));
+  svfloat64_t y = sv_log1p_inline (svadd_x (pg, xm1, svsqrt_x (pg, u)), pg);
+
+  /* Fall back to scalar routine for special lanes.  */
+  if (unlikely (svptest_any (pg, special)))
+    return special_case (x, y, special);
+
+  return y;
+}
+
+PL_SIG (SV, D, 1, acosh, 1.0, 10.0)
+PL_TEST_ULP (SV_NAME_D1 (acosh), 2.69)
+PL_TEST_INTERVAL (SV_NAME_D1 (acosh), 1, 0x1p511, 90000)
+PL_TEST_INTERVAL (SV_NAME_D1 (acosh), 0x1p511, inf, 10000)
+PL_TEST_INTERVAL (SV_NAME_D1 (acosh), 0, 1, 1000)
+PL_TEST_INTERVAL (SV_NAME_D1 (acosh), -0, -inf, 10000)