[libc-commits] [libc] accee2b - [libc][math][c23] Add atanhf16 C23 math function. (#132612)
via libc-commits
libc-commits at lists.llvm.org
Fri Apr 25 04:53:56 PDT 2025
Author: Harrison Hao
Date: 2025-04-25T07:53:52-04:00
New Revision: accee2b5538eedae297201d1a2d66ddefd4c0cc1
URL: https://github.com/llvm/llvm-project/commit/accee2b5538eedae297201d1a2d66ddefd4c0cc1
DIFF: https://github.com/llvm/llvm-project/commit/accee2b5538eedae297201d1a2d66ddefd4c0cc1.diff
LOG: [libc][math][c23] Add atanhf16 C23 math function. (#132612)
Implementation of atanhf16 function for 16-bit inputs.
Closes: https://github.com/llvm/llvm-project/issues/132209
Added:
libc/src/math/atanhf16.h
libc/src/math/generic/atanhf16.cpp
libc/test/src/math/atanhf16_test.cpp
libc/test/src/math/smoke/atanhf16_test.cpp
Modified:
libc/config/linux/x86_64/entrypoints.txt
libc/docs/headers/math/index.rst
libc/include/math.yaml
libc/src/math/CMakeLists.txt
libc/src/math/generic/CMakeLists.txt
libc/src/math/generic/common_constants.cpp
libc/src/math/generic/common_constants.h
libc/src/math/generic/explogxf.h
libc/test/src/math/CMakeLists.txt
libc/test/src/math/smoke/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 0e4fbdd2f2f57..641e0a942e7bd 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -665,6 +665,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.acospif16
libc.src.math.asinf16
libc.src.math.asinhf16
+ libc.src.math.atanhf16
libc.src.math.canonicalizef16
libc.src.math.ceilf16
libc.src.math.copysignf16
diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst
index cf88e6237d1e3..95366a614ac6a 100644
--- a/libc/docs/headers/math/index.rst
+++ b/libc/docs/headers/math/index.rst
@@ -267,7 +267,7 @@ Higher Math Functions
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| atan2pi | | | | | | 7.12.4.11 | F.10.1.11 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| atanh | |check| | | | | | 7.12.5.3 | F.10.2.3 |
+| atanh | |check| | | | |check| | | 7.12.5.3 | F.10.2.3 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| atanpi | | | | | | 7.12.4.10 | F.10.1.10 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/include/math.yaml b/libc/include/math.yaml
index b725c33c0bb06..f8c57f7d48ab2 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -120,6 +120,13 @@ functions:
return_type: float
arguments:
- type: float
+ - name: atanhf16
+ standards:
+ - stdc
+ return_type: _Float16
+ arguments:
+ - type: _Float16
+ guard: LIBC_TYPES_HAS_FLOAT16
- name: canonicalize
standards:
- stdc
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 5161b2b61aa94..055e76468a461 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -68,6 +68,7 @@ add_math_entrypoint_object(atan2f128)
add_math_entrypoint_object(atanh)
add_math_entrypoint_object(atanhf)
+add_math_entrypoint_object(atanhf16)
add_math_entrypoint_object(canonicalize)
add_math_entrypoint_object(canonicalizef)
diff --git a/libc/src/math/atanhf16.h b/libc/src/math/atanhf16.h
new file mode 100644
index 0000000000000..9fbb262c16514
--- /dev/null
+++ b/libc/src/math/atanhf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for atanhf16 ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_MATH_ATANHF16_H
+#define LLVM_LIBC_SRC_MATH_ATANHF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 atanhf16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_ATANHF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 25f583035fbc2..402969d3b7085 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -4029,6 +4029,26 @@ add_entrypoint_object(
libc.src.__support.macros.optimization
)
+add_entrypoint_object(
+ atanhf16
+ SRCS
+ atanhf16.cpp
+ HDRS
+ ../atanhf16.h
+ DEPENDS
+ .explogxf
+ libc.hdr.errno_macros
+ libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.except_value_utils
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.FPUtil.polyeval
+ libc.src.__support.macros.optimization
+ libc.src.__support.macros.properties.types
+)
+
add_object_library(
inv_trigf_utils
HDRS
diff --git a/libc/src/math/generic/atanhf16.cpp b/libc/src/math/generic/atanhf16.cpp
new file mode 100644
index 0000000000000..57885ac0b767f
--- /dev/null
+++ b/libc/src/math/generic/atanhf16.cpp
@@ -0,0 +1,98 @@
+//===-- Half-precision atanh(x) function ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/atanhf16.h"
+#include "explogxf.h"
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static constexpr size_t N_EXCEPTS = 1;
+static constexpr fputil::ExceptValues<float16, N_EXCEPTS> ATANHF16_EXCEPTS{{
+ // (input, RZ output, RU offset, RD offset, RN offset)
+ // x = 0x1.a5cp-4, atanhf16(x) = 0x1.a74p-4 (RZ)
+ {0x2E97, 0x2E9D, 1, 0, 0},
+}};
+
+LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
+ using FPBits = fputil::FPBits<float16>;
+
+ FPBits xbits(x);
+ Sign sign = xbits.sign();
+ uint16_t x_abs = xbits.abs().uintval();
+
+ // |x| >= 1
+ if (LIBC_UNLIKELY(x_abs >= 0x3c00U)) {
+ if (xbits.is_nan()) {
+ if (xbits.is_signaling_nan()) {
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ return x;
+ }
+
+ // |x| == 1.0
+ if (x_abs == 0x3c00U) {
+ fputil::set_errno_if_required(ERANGE);
+ fputil::raise_except_if_required(FE_DIVBYZERO);
+ return FPBits::inf(sign).get_val();
+ }
+ // |x| > 1.0
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+
+ if (auto r = ATANHF16_EXCEPTS.lookup(xbits.uintval());
+ LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+
+ // For |x| less than approximately 0.24
+ if (LIBC_UNLIKELY(x_abs <= 0x33f3U)) {
+ // atanh(+/-0) = +/-0
+ if (LIBC_UNLIKELY(x_abs == 0U))
+ return x;
+ // The Taylor expansion of atanh(x) is:
+ // atanh(x) = x + x^3/3 + x^5/5 + x^7/7 + x^9/9 + x^11/11
+ // = x * [1 + x^2/3 + x^4/5 + x^6/7 + x^8/9 + x^10/11]
+ // When |x| < 2^-5 (0x0800U), this can be approximated by:
+ // atanh(x) ≈ x + (1/3)*x^3
+ if (LIBC_UNLIKELY(x_abs < 0x0800U)) {
+ float xf = x;
+ return fputil::cast<float16>(xf + 0x1.555556p-2f * xf * xf * xf);
+ }
+
+ // For 2^-5 <= |x| <= 0x1.fccp-3 (~0.24):
+ // Let t = x^2.
+ // Define P(t) ≈ (1/3)*t + (1/5)*t^2 + (1/7)*t^3 + (1/9)*t^4 + (1/11)*t^5.
+ // Coefficients (from Sollya, RN, hexadecimal):
+ // 1/3 = 0x1.555556p-2, 1/5 = 0x1.99999ap-3, 1/7 = 0x1.24924ap-3,
+ // 1/9 = 0x1.c71c72p-4, 1/11 = 0x1.745d18p-4
+ // Thus, atanh(x) ≈ x * (1 + P(x^2)).
+ float xf = x;
+ float x2 = xf * xf;
+ float pe = fputil::polyeval(x2, 0.0f, 0x1.555556p-2f, 0x1.99999ap-3f,
+ 0x1.24924ap-3f, 0x1.c71c72p-4f, 0x1.745d18p-4f);
+ return fputil::cast<float16>(fputil::multiply_add(xf, pe, xf));
+ }
+
+ float xf = x;
+ return fputil::cast<float16>(0.5 * log_eval_f((xf + 1.0f) / (xf - 1.0f)));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/common_constants.cpp b/libc/src/math/generic/common_constants.cpp
index 3088ef96e3b93..b2c1293c6326d 100644
--- a/libc/src/math/generic/common_constants.cpp
+++ b/libc/src/math/generic/common_constants.cpp
@@ -13,6 +13,45 @@
namespace LIBC_NAMESPACE_DECL {
+// Lookup table for logf(f) = logf(1 + n*2^(-7)) where n = 0..127,
+// computed and stored as float precision constants.
+// Generated by Sollya with the following commands:
+// display = hexadecimal;
+// for n from 0 to 127 do { print(single(1 / (1 + n / 128.0))); };
+const float ONE_OVER_F_FLOAT[128] = {
+ 0x1p0f, 0x1.fc07fp-1f, 0x1.f81f82p-1f, 0x1.f4465ap-1f,
+ 0x1.f07c2p-1f, 0x1.ecc07cp-1f, 0x1.e9131ap-1f, 0x1.e573acp-1f,
+ 0x1.e1e1e2p-1f, 0x1.de5d6ep-1f, 0x1.dae608p-1f, 0x1.d77b66p-1f,
+ 0x1.d41d42p-1f, 0x1.d0cb58p-1f, 0x1.cd8568p-1f, 0x1.ca4b3p-1f,
+ 0x1.c71c72p-1f, 0x1.c3f8fp-1f, 0x1.c0e07p-1f, 0x1.bdd2b8p-1f,
+ 0x1.bacf92p-1f, 0x1.b7d6c4p-1f, 0x1.b4e81cp-1f, 0x1.b20364p-1f,
+ 0x1.af286cp-1f, 0x1.ac5702p-1f, 0x1.a98ef6p-1f, 0x1.a6d01ap-1f,
+ 0x1.a41a42p-1f, 0x1.a16d4p-1f, 0x1.9ec8eap-1f, 0x1.9c2d14p-1f,
+ 0x1.99999ap-1f, 0x1.970e5p-1f, 0x1.948b1p-1f, 0x1.920fb4p-1f,
+ 0x1.8f9c18p-1f, 0x1.8d3018p-1f, 0x1.8acb9p-1f, 0x1.886e6p-1f,
+ 0x1.861862p-1f, 0x1.83c978p-1f, 0x1.818182p-1f, 0x1.7f406p-1f,
+ 0x1.7d05f4p-1f, 0x1.7ad22p-1f, 0x1.78a4c8p-1f, 0x1.767dcep-1f,
+ 0x1.745d18p-1f, 0x1.724288p-1f, 0x1.702e06p-1f, 0x1.6e1f76p-1f,
+ 0x1.6c16c2p-1f, 0x1.6a13cep-1f, 0x1.681682p-1f, 0x1.661ec6p-1f,
+ 0x1.642c86p-1f, 0x1.623fa8p-1f, 0x1.605816p-1f, 0x1.5e75bcp-1f,
+ 0x1.5c9882p-1f, 0x1.5ac056p-1f, 0x1.58ed24p-1f, 0x1.571ed4p-1f,
+ 0x1.555556p-1f, 0x1.539094p-1f, 0x1.51d07ep-1f, 0x1.501502p-1f,
+ 0x1.4e5e0ap-1f, 0x1.4cab88p-1f, 0x1.4afd6ap-1f, 0x1.49539ep-1f,
+ 0x1.47ae14p-1f, 0x1.460cbcp-1f, 0x1.446f86p-1f, 0x1.42d662p-1f,
+ 0x1.414142p-1f, 0x1.3fb014p-1f, 0x1.3e22ccp-1f, 0x1.3c995ap-1f,
+ 0x1.3b13b2p-1f, 0x1.3991c2p-1f, 0x1.381382p-1f, 0x1.3698ep-1f,
+ 0x1.3521dp-1f, 0x1.33ae46p-1f, 0x1.323e34p-1f, 0x1.30d19p-1f,
+ 0x1.2f684cp-1f, 0x1.2e025cp-1f, 0x1.2c9fb4p-1f, 0x1.2b404ap-1f,
+ 0x1.29e412p-1f, 0x1.288b02p-1f, 0x1.27350cp-1f, 0x1.25e228p-1f,
+ 0x1.24924ap-1f, 0x1.234568p-1f, 0x1.21fb78p-1f, 0x1.20b47p-1f,
+ 0x1.1f7048p-1f, 0x1.1e2ef4p-1f, 0x1.1cf06ap-1f, 0x1.1bb4a4p-1f,
+ 0x1.1a7b96p-1f, 0x1.194538p-1f, 0x1.181182p-1f, 0x1.16e068p-1f,
+ 0x1.15b1e6p-1f, 0x1.1485fp-1f, 0x1.135c82p-1f, 0x1.12358ep-1f,
+ 0x1.111112p-1f, 0x1.0fef02p-1f, 0x1.0ecf56p-1f, 0x1.0db20ap-1f,
+ 0x1.0c9714p-1f, 0x1.0b7e6ep-1f, 0x1.0a681p-1f, 0x1.0953f4p-1f,
+ 0x1.08421p-1f, 0x1.07326p-1f, 0x1.0624dep-1f, 0x1.05198p-1f,
+ 0x1.041042p-1f, 0x1.03091cp-1f, 0x1.020408p-1f, 0x1.010102p-1f};
+
// Lookup table for (1/f) where f = 1 + n*2^(-7), n = 0..127.
const double ONE_OVER_F[128] = {
0x1.0000000000000p+0, 0x1.fc07f01fc07f0p-1, 0x1.f81f81f81f820p-1,
@@ -59,6 +98,45 @@ const double ONE_OVER_F[128] = {
0x1.05197f7d73404p-1, 0x1.0410410410410p-1, 0x1.03091b51f5e1ap-1,
0x1.0204081020408p-1, 0x1.0101010101010p-1};
+// Lookup table for log(f) = log(1 + n*2^(-7)) where n = 0..127,
+// computed and stored as float precision constants.
+// Generated by Sollya with the following commands:
+// display = hexadecimal;
+// for n from 0 to 127 do { print(single(log(1 + n / 128.0))); };
+const float LOG_F_FLOAT[128] = {
+ 0.0f, 0x1.fe02a6p-8f, 0x1.fc0a8cp-7f, 0x1.7b91bp-6f,
+ 0x1.f829bp-6f, 0x1.39e87cp-5f, 0x1.77459p-5f, 0x1.b42dd8p-5f,
+ 0x1.f0a30cp-5f, 0x1.16536ep-4f, 0x1.341d7ap-4f, 0x1.51b074p-4f,
+ 0x1.6f0d28p-4f, 0x1.8c345ep-4f, 0x1.a926d4p-4f, 0x1.c5e548p-4f,
+ 0x1.e27076p-4f, 0x1.fec914p-4f, 0x1.0d77e8p-3f, 0x1.1b72aep-3f,
+ 0x1.29553p-3f, 0x1.371fc2p-3f, 0x1.44d2b6p-3f, 0x1.526e5ep-3f,
+ 0x1.5ff308p-3f, 0x1.6d60fep-3f, 0x1.7ab89p-3f, 0x1.87fa06p-3f,
+ 0x1.9525aap-3f, 0x1.a23bc2p-3f, 0x1.af3c94p-3f, 0x1.bc2868p-3f,
+ 0x1.c8ff7cp-3f, 0x1.d5c216p-3f, 0x1.e27076p-3f, 0x1.ef0adcp-3f,
+ 0x1.fb9186p-3f, 0x1.04025ap-2f, 0x1.0a324ep-2f, 0x1.1058cp-2f,
+ 0x1.1675cap-2f, 0x1.1c898cp-2f, 0x1.22942p-2f, 0x1.2895a2p-2f,
+ 0x1.2e8e2cp-2f, 0x1.347ddap-2f, 0x1.3a64c6p-2f, 0x1.404308p-2f,
+ 0x1.4618bcp-2f, 0x1.4be5fap-2f, 0x1.51aad8p-2f, 0x1.576772p-2f,
+ 0x1.5d1bdcp-2f, 0x1.62c83p-2f, 0x1.686c82p-2f, 0x1.6e08eap-2f,
+ 0x1.739d8p-2f, 0x1.792a56p-2f, 0x1.7eaf84p-2f, 0x1.842d1ep-2f,
+ 0x1.89a338p-2f, 0x1.8f11e8p-2f, 0x1.947942p-2f, 0x1.99d958p-2f,
+ 0x1.9f323ep-2f, 0x1.a4840ap-2f, 0x1.a9cecap-2f, 0x1.af1294p-2f,
+ 0x1.b44f78p-2f, 0x1.b9858ap-2f, 0x1.beb4dap-2f, 0x1.c3dd7ap-2f,
+ 0x1.c8ff7cp-2f, 0x1.ce1afp-2f, 0x1.d32fe8p-2f, 0x1.d83e72p-2f,
+ 0x1.dd46ap-2f, 0x1.e24882p-2f, 0x1.e74426p-2f, 0x1.ec399ep-2f,
+ 0x1.f128f6p-2f, 0x1.f6124p-2f, 0x1.faf588p-2f, 0x1.ffd2ep-2f,
+ 0x1.02552ap-1f, 0x1.04bdfap-1f, 0x1.0723e6p-1f, 0x1.0986f4p-1f,
+ 0x1.0be72ep-1f, 0x1.0e4498p-1f, 0x1.109f3ap-1f, 0x1.12f71ap-1f,
+ 0x1.154c3ep-1f, 0x1.179eacp-1f, 0x1.19ee6cp-1f, 0x1.1c3b82p-1f,
+ 0x1.1e85f6p-1f, 0x1.20cdcep-1f, 0x1.23130ep-1f, 0x1.2555bcp-1f,
+ 0x1.2795e2p-1f, 0x1.29d38p-1f, 0x1.2c0e9ep-1f, 0x1.2e4744p-1f,
+ 0x1.307d74p-1f, 0x1.32b134p-1f, 0x1.34e28ap-1f, 0x1.37117cp-1f,
+ 0x1.393e0ep-1f, 0x1.3b6844p-1f, 0x1.3d9026p-1f, 0x1.3fb5b8p-1f,
+ 0x1.41d8fep-1f, 0x1.43f9fep-1f, 0x1.4618bcp-1f, 0x1.48353ep-1f,
+ 0x1.4a4f86p-1f, 0x1.4c679ap-1f, 0x1.4e7d82p-1f, 0x1.50913cp-1f,
+ 0x1.52a2d2p-1f, 0x1.54b246p-1f, 0x1.56bf9ep-1f, 0x1.58cadcp-1f,
+ 0x1.5ad404p-1f, 0x1.5cdb1ep-1f, 0x1.5ee02ap-1f, 0x1.60e33p-1f};
+
// Lookup table for log(f) = log(1 + n*2^(-7)) where n = 0..127.
const double LOG_F[128] = {
0x0.0000000000000p+0, 0x1.fe02a6b106788p-8, 0x1.fc0a8b0fc03e3p-7,
diff --git a/libc/src/math/generic/common_constants.h b/libc/src/math/generic/common_constants.h
index dc1a90c1cb24a..e65f002845953 100644
--- a/libc/src/math/generic/common_constants.h
+++ b/libc/src/math/generic/common_constants.h
@@ -15,9 +15,17 @@
namespace LIBC_NAMESPACE_DECL {
+// Lookup table for (1/f) where f = 1 + n*2^(-7), n = 0..127,
+// computed and stored as float precision constants.
+extern const float ONE_OVER_F_FLOAT[128];
+
// Lookup table for (1/f) where f = 1 + n*2^(-7), n = 0..127.
extern const double ONE_OVER_F[128];
+// Lookup table for log(f) = log(1 + n*2^(-7)) where n = 0..127,
+// computed and stored as float precision constants.
+extern const float LOG_F_FLOAT[128];
+
// Lookup table for log(f) = log(1 + n*2^(-7)) where n = 0..127.
extern const double LOG_F[128];
diff --git a/libc/src/math/generic/explogxf.h b/libc/src/math/generic/explogxf.h
index e79aa13eb57f7..212ede4758549 100644
--- a/libc/src/math/generic/explogxf.h
+++ b/libc/src/math/generic/explogxf.h
@@ -297,6 +297,49 @@ LIBC_INLINE static double log2_eval(double x) {
return result;
}
+// x should be positive, normal finite value
+// TODO: Simplify range reduction and polynomial degree for float16.
+// See issue #137190.
+LIBC_INLINE static float log_eval_f(float x) {
+ // For x = 2^ex * (1 + mx), logf(x) = ex * logf(2) + logf(1 + mx).
+ using FPBits = fputil::FPBits<float>;
+ FPBits xbits(x);
+
+ float ex = static_cast<float>(xbits.get_exponent());
+ // p1 is the leading 7 bits of mx, i.e.
+ // p1 * 2^(-7) <= m_x < (p1 + 1) * 2^(-7).
+ int p1 = static_cast<int>(xbits.get_mantissa() >> (FPBits::FRACTION_LEN - 7));
+
+ // Set bits to (1 + (mx - p1*2^(-7)))
+ xbits.set_uintval(xbits.uintval() & (FPBits::FRACTION_MASK >> 7));
+ xbits.set_biased_exponent(FPBits::EXP_BIAS);
+ // dx = (mx - p1*2^(-7)) / (1 + p1*2^(-7)).
+ float dx = (xbits.get_val() - 1.0f) * ONE_OVER_F_FLOAT[p1];
+
+ // Minimax polynomial for log(1 + dx), generated using Sollya:
+ // > P = fpminimax(log(1 + x)/x, 6, [|SG...|], [0, 2^-7]);
+ // > Q = (P - 1) / x;
+ // > for i from 0 to degree(Q) do print(coeff(Q, i));
+ constexpr float COEFFS[6] = {-0x1p-1f, 0x1.555556p-2f, -0x1.00022ep-2f,
+ 0x1.9ea056p-3f, -0x1.e50324p-2f, 0x1.c018fp3f};
+
+ float dx2 = dx * dx;
+
+ float c1 = fputil::multiply_add(dx, COEFFS[1], COEFFS[0]);
+ float c2 = fputil::multiply_add(dx, COEFFS[3], COEFFS[2]);
+ float c3 = fputil::multiply_add(dx, COEFFS[5], COEFFS[4]);
+
+ float p = fputil::polyeval(dx2, dx, c1, c2, c3);
+
+ // Generated by Sollya with the following commands:
+ // > display = hexadecimal;
+ // > round(log(2), SG, RN);
+ constexpr float LOGF_2 = 0x1.62e43p-1f;
+
+ float result = fputil::multiply_add(ex, LOGF_2, LOG_F_FLOAT[p1] + p);
+ return result;
+}
+
// x should be positive, normal finite value
LIBC_INLINE static double log_eval(double x) {
// For x = 2^ex * (1 + mx)
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index ebf9f1c86cf15..a28639ab15f44 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -2143,6 +2143,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ atanhf16_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ atanhf16_test.cpp
+ DEPENDS
+ libc.src.math.atanhf16
+)
+
add_fp_unittest(
fmul_test
NEED_MPFR
diff --git a/libc/test/src/math/atanhf16_test.cpp b/libc/test/src/math/atanhf16_test.cpp
new file mode 100644
index 0000000000000..e35cc775b0609
--- /dev/null
+++ b/libc/test/src/math/atanhf16_test.cpp
@@ -0,0 +1,40 @@
+//===-- Unittests for atanhf16 --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/atanhf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+#include <stdint.h>
+
+using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range for positive numbers: [0, +Inf]
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x7C00U;
+
+// Range for negative numbers: [-Inf, 0]
+static constexpr uint16_t NEG_START = 0x8000U;
+static constexpr uint16_t NEG_STOP = 0xFC00U;
+
+TEST_F(LlvmLibcAtanhf16Test, PositiveRange) {
+ for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Atanh, x,
+ LIBC_NAMESPACE::atanhf16(x), 0.5);
+ }
+}
+
+TEST_F(LlvmLibcAtanhf16Test, NegativeRange) {
+ for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Atanh, x,
+ LIBC_NAMESPACE::atanhf16(x), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 79b189159e9d8..356ec12e064b3 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3947,6 +3947,18 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ atanhf16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ atanhf16_test.cpp
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.math.atanhf16
+ libc.src.__support.FPUtil.cast
+)
+
add_fp_unittest(
asinhf_test
SUITE
diff --git a/libc/test/src/math/smoke/atanhf16_test.cpp b/libc/test/src/math/smoke/atanhf16_test.cpp
new file mode 100644
index 0000000000000..81df6da8cee26
--- /dev/null
+++ b/libc/test/src/math/smoke/atanhf16_test.cpp
@@ -0,0 +1,60 @@
+//===-- Unittests for atanhf16 --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/FPUtil/cast.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/atanhf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcAtanhf16Test, SpecialNumbers) {
+ LIBC_NAMESPACE::libc_errno = 0;
+ EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::atanhf16(sNaN),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::atanhf16(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(zero, LIBC_NAMESPACE::atanhf16(zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(neg_zero, LIBC_NAMESPACE::atanhf16(neg_zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(
+ inf,
+ LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(1.0f)),
+ FE_DIVBYZERO);
+ EXPECT_MATH_ERRNO(ERANGE);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(
+ neg_inf,
+ LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-1.0f)),
+ FE_DIVBYZERO);
+ EXPECT_MATH_ERRNO(ERANGE);
+
+ EXPECT_FP_IS_NAN_WITH_EXCEPTION(
+ LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(2.0f)),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_IS_NAN_WITH_EXCEPTION(
+ LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-2.0f)),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_IS_NAN_WITH_EXCEPTION(LIBC_NAMESPACE::atanhf16(inf), FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_IS_NAN_WITH_EXCEPTION(LIBC_NAMESPACE::atanhf16(neg_inf),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+}
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