[libc-commits] [libc] [libc][math][c23] Add atanhf16 C23 math function. (PR #132612)
Harrison Hao via libc-commits
libc-commits at lists.llvm.org
Sun Mar 30 18:55:06 PDT 2025
https://github.com/harrisonGPU updated https://github.com/llvm/llvm-project/pull/132612
>From 75ca18b20dce714137316676b94d8fc533fee326 Mon Sep 17 00:00:00 2001
From: Harrison Hao <tsworld1314 at gmail.com>
Date: Mon, 17 Mar 2025 15:34:24 +0000
Subject: [PATCH 1/5] [libc][math][c23] Add atanhf16 C23 math function.
---
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/docs/headers/math/index.rst | 2 +-
libc/include/math.yaml | 7 ++
libc/src/math/CMakeLists.txt | 1 +
libc/src/math/atanhf16.h | 21 ++++++
libc/src/math/generic/CMakeLists.txt | 18 +++++
libc/src/math/generic/atanhf16.cpp | 86 ++++++++++++++++++++++
libc/test/src/math/CMakeLists.txt | 11 +++
libc/test/src/math/atanhf16_test.cpp | 39 ++++++++++
libc/test/src/math/smoke/CMakeLists.txt | 12 +++
libc/test/src/math/smoke/atanhf16_test.cpp | 58 +++++++++++++++
11 files changed, 255 insertions(+), 1 deletion(-)
create mode 100644 libc/src/math/atanhf16.h
create mode 100644 libc/src/math/generic/atanhf16.cpp
create mode 100644 libc/test/src/math/atanhf16_test.cpp
create mode 100644 libc/test/src/math/smoke/atanhf16_test.cpp
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 648e3d5ac5281..d951a4572be2e 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -657,6 +657,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.acoshf16
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 23d010e2ab5d7..b3a28778658dd 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 3a06bcfc4f43e..1f607624ef204 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -105,6 +105,13 @@ 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 9fec978ece2bd..b068e6eaf2ae2 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -65,6 +65,7 @@ add_math_entrypoint_object(atan2l)
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 d3454803df377..428cf89d60811 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -4013,6 +4013,24 @@ 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.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..94d6aa149cf00
--- /dev/null
+++ b/libc/src/math/generic/atanhf16.cpp
@@ -0,0 +1,86 @@
+//===-- Implementation of 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/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/cast.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 {
+
+LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
+ using FPBits = typename fputil::FPBits<float16>;
+
+ FPBits xbits(x);
+ Sign sign = xbits.sign();
+ uint16_t x_abs = xbits.abs().uintval();
+
+ if (LIBC_UNLIKELY(x_abs >= 0x3c00U)) {
+ if (xbits.is_nan()) {
+ 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();
+ } else {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ }
+
+ // For |x| less than approximately 0.10
+ if (LIBC_UNLIKELY(x_abs <= 0x2e66U)) {
+ // 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| < 0x0100U, this can be approximated by:
+ // atanh(x) ≈ x + (1/3)*x^3
+ if (LIBC_UNLIKELY(x_abs < 0x0100U)) {
+ return static_cast<float16>(
+ LIBC_UNLIKELY(x_abs == 0) ? x : (x + 0x1.555556p-2 * x * x * x));
+ }
+
+ // For 0x0100U <= |x| <= 0x2e66U:
+ // 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.
+ // The coefficients below were derived using Sollya:
+ // > display = hexadecimal;
+ // > round(1/3, SG, RN);
+ // > round(1/5, SG, RN);
+ // > round(1/7, SG, RN);
+ // > round(1/9, SG, RN);
+ // > round(1/11, SG, RN);
+ // This yields:
+ // 0x1.555556p-2
+ // 0x1.99999ap-3
+ // 0x1.24924ap-3
+ // 0x1.c71c72p-4
+ // 0x1.745d18p-4f
+ // 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 static_cast<float16>(fputil::multiply_add(xf, pe, xf));
+ }
+
+ float xf = x;
+ return static_cast<float16>(0.5 * log_eval((xf + 1.0) / (xf - 1.0)));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 9a73f9fe07597..564da1d5120dc 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -2132,6 +2132,17 @@ 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..ce0179a1962df
--- /dev/null
+++ b/libc/test/src/math/atanhf16_test.cpp
@@ -0,0 +1,39 @@
+//===-- 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/FPBits.h"
+#include "src/errno/libc_errno.h"
+#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;
+
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x3BFFU;
+static constexpr uint16_t NEG_START = 0xBBFFU;
+static constexpr uint16_t NEG_STOP = 0x8000U;
+
+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 b7601735c1109..a9d61bc3bd76c 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3934,6 +3934,18 @@ 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.fp_bits
+)
+
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..1ac483d2ae758
--- /dev/null
+++ b/libc/test/src/math/smoke/atanhf16_test.cpp
@@ -0,0 +1,58 @@
+//===-- 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_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(
+ -0.0f,
+ LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-0.0f)));
+ 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);
+}
>From 967fa8b2ee2698c18d926e7baa940e72d92fc58b Mon Sep 17 00:00:00 2001
From: Harrison Hao <tsworld1314 at gmail.com>
Date: Wed, 26 Mar 2025 10:18:23 +0800
Subject: [PATCH 2/5] [libc][math] Update range.
---
libc/test/src/math/atanhf16_test.cpp | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/libc/test/src/math/atanhf16_test.cpp b/libc/test/src/math/atanhf16_test.cpp
index ce0179a1962df..6637c7eead8f5 100644
--- a/libc/test/src/math/atanhf16_test.cpp
+++ b/libc/test/src/math/atanhf16_test.cpp
@@ -17,13 +17,16 @@
using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+// Range for positive numbers: [0, 1)
static constexpr uint16_t POS_START = 0x0000U;
-static constexpr uint16_t POS_STOP = 0x3BFFU;
+static constexpr uint16_t POS_STOP = 0x3C00;
+
+// Range for negative numbers: (-1, 0]
static constexpr uint16_t NEG_START = 0xBBFFU;
static constexpr uint16_t NEG_STOP = 0x8000U;
TEST_F(LlvmLibcAtanhf16Test, PositiveRange) {
- for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+ 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);
@@ -31,7 +34,7 @@ TEST_F(LlvmLibcAtanhf16Test, PositiveRange) {
}
TEST_F(LlvmLibcAtanhf16Test, NegativeRange) {
- for (uint16_t v = NEG_START; v <= NEG_STOP; --v) {
+ 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);
>From a6aca867fd4a353c2a8797f9981177e64f19e7d2 Mon Sep 17 00:00:00 2001
From: Harrison Hao <tsworld1314 at gmail.com>
Date: Sat, 29 Mar 2025 06:10:45 +0000
Subject: [PATCH 3/5] [libc][math][c23] Update for comments.
---
libc/src/math/generic/CMakeLists.txt | 1 +
libc/src/math/generic/atanhf16.cpp | 40 +++++++++-------------
libc/test/src/math/atanhf16_test.cpp | 13 ++++---
libc/test/src/math/smoke/atanhf16_test.cpp | 4 +--
4 files changed, 24 insertions(+), 34 deletions(-)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 428cf89d60811..3923c846ff391 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -4024,6 +4024,7 @@ add_entrypoint_object(
libc.hdr.errno_macros
libc.hdr.fenv_macros
libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.fenv_impl
libc.src.__support.FPUtil.fp_bits
libc.src.__support.FPUtil.multiply_add
libc.src.__support.FPUtil.polyeval
diff --git a/libc/src/math/generic/atanhf16.cpp b/libc/src/math/generic/atanhf16.cpp
index 94d6aa149cf00..bb16a78a9862d 100644
--- a/libc/src/math/generic/atanhf16.cpp
+++ b/libc/src/math/generic/atanhf16.cpp
@@ -1,4 +1,4 @@
-//===-- Implementation of atanh(x) function -------------------------------===//
+//===-- 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.
@@ -10,6 +10,7 @@
#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"
@@ -21,26 +22,27 @@
namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
- using FPBits = typename fputil::FPBits<float16>;
+ 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_nan())
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();
- } else {
- fputil::set_errno_if_required(EDOM);
- fputil::raise_except_if_required(FE_INVALID);
- return FPBits::quiet_nan().get_val();
}
+ // |x| > 1.0
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
}
// For |x| less than approximately 0.10
@@ -52,35 +54,25 @@ LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
// atanh(x) ≈ x + (1/3)*x^3
if (LIBC_UNLIKELY(x_abs < 0x0100U)) {
return static_cast<float16>(
- LIBC_UNLIKELY(x_abs == 0) ? x : (x + 0x1.555556p-2 * x * x * x));
+ LIBC_UNLIKELY(x_abs == 0) ? x : (x + 0x1.555556p-2f * x * x * x));
}
// For 0x0100U <= |x| <= 0x2e66U:
// 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.
- // The coefficients below were derived using Sollya:
- // > display = hexadecimal;
- // > round(1/3, SG, RN);
- // > round(1/5, SG, RN);
- // > round(1/7, SG, RN);
- // > round(1/9, SG, RN);
- // > round(1/11, SG, RN);
- // This yields:
- // 0x1.555556p-2
- // 0x1.99999ap-3
- // 0x1.24924ap-3
- // 0x1.c71c72p-4
- // 0x1.745d18p-4f
+ // 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 static_cast<float16>(fputil::multiply_add(xf, pe, xf));
+ return fputil::cast<float16>(fputil::multiply_add(xf, pe, xf));
}
float xf = x;
- return static_cast<float16>(0.5 * log_eval((xf + 1.0) / (xf - 1.0)));
+ return fputil::cast<float16>(0.5 * log_eval((xf + 1.0) / (xf - 1.0)));
}
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/src/math/atanhf16_test.cpp b/libc/test/src/math/atanhf16_test.cpp
index 6637c7eead8f5..a534e05230e9d 100644
--- a/libc/test/src/math/atanhf16_test.cpp
+++ b/libc/test/src/math/atanhf16_test.cpp
@@ -7,7 +7,6 @@
//===----------------------------------------------------------------------===//
#include "src/__support/FPUtil/FPBits.h"
-#include "src/errno/libc_errno.h"
#include "src/math/atanhf16.h"
#include "test/UnitTest/FPMatcher.h"
#include "test/UnitTest/Test.h"
@@ -17,13 +16,13 @@
using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
-// Range for positive numbers: [0, 1)
+// Range for positive numbers: [0, +Inf]
static constexpr uint16_t POS_START = 0x0000U;
-static constexpr uint16_t POS_STOP = 0x3C00;
+static constexpr uint16_t POS_STOP = 0x7C00U;
-// Range for negative numbers: (-1, 0]
-static constexpr uint16_t NEG_START = 0xBBFFU;
-static constexpr uint16_t NEG_STOP = 0x8000U;
+// 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) {
@@ -34,7 +33,7 @@ TEST_F(LlvmLibcAtanhf16Test, PositiveRange) {
}
TEST_F(LlvmLibcAtanhf16Test, NegativeRange) {
- for (uint16_t v = NEG_START; v >= NEG_STOP; --v) {
+ 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/atanhf16_test.cpp b/libc/test/src/math/smoke/atanhf16_test.cpp
index 1ac483d2ae758..1e81d5f18c0b2 100644
--- a/libc/test/src/math/smoke/atanhf16_test.cpp
+++ b/libc/test/src/math/smoke/atanhf16_test.cpp
@@ -22,9 +22,7 @@ TEST_F(LlvmLibcAtanhf16Test, SpecialNumbers) {
EXPECT_FP_EQ_ALL_ROUNDING(zero, LIBC_NAMESPACE::atanhf16(zero));
EXPECT_MATH_ERRNO(0);
- EXPECT_FP_EQ_ALL_ROUNDING(
- -0.0f,
- LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-0.0f)));
+ EXPECT_FP_EQ_ALL_ROUNDING(neg_zero, LIBC_NAMESPACE::atanhf16(neg_zero));
EXPECT_MATH_ERRNO(0);
EXPECT_FP_EQ_WITH_EXCEPTION(
>From 2df9c7a58b2cdd8359af00e79d93ef41d2f0aa1c Mon Sep 17 00:00:00 2001
From: Harrison Hao <tsworld1314 at gmail.com>
Date: Sat, 29 Mar 2025 08:31:20 +0000
Subject: [PATCH 4/5] [libc][math] Update.
---
libc/src/math/generic/atanhf16.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/src/math/generic/atanhf16.cpp b/libc/src/math/generic/atanhf16.cpp
index bb16a78a9862d..6b4d6abd15ba0 100644
--- a/libc/src/math/generic/atanhf16.cpp
+++ b/libc/src/math/generic/atanhf16.cpp
@@ -72,7 +72,7 @@ LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
}
float xf = x;
- return fputil::cast<float16>(0.5 * log_eval((xf + 1.0) / (xf - 1.0)));
+ return fputil::cast<float16>(0.5f * log_eval((xf + 1.0f) / (xf - 1.0f)));
}
} // namespace LIBC_NAMESPACE_DECL
>From 0f13717cf4e3801bf4e232b4d15732a037782b1b Mon Sep 17 00:00:00 2001
From: Harrison Hao <tsworld1314 at gmail.com>
Date: Sat, 29 Mar 2025 09:49:10 +0000
Subject: [PATCH 5/5] [libc][math] Add except results.
---
libc/src/math/generic/atanhf16.cpp | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/libc/src/math/generic/atanhf16.cpp b/libc/src/math/generic/atanhf16.cpp
index 6b4d6abd15ba0..e2d067be6582b 100644
--- a/libc/src/math/generic/atanhf16.cpp
+++ b/libc/src/math/generic/atanhf16.cpp
@@ -14,6 +14,7 @@
#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"
@@ -21,6 +22,15 @@
namespace LIBC_NAMESPACE_DECL {
+static constexpr size_t N_EXCEPTS = 2;
+static constexpr fputil::ExceptValues<float16, N_EXCEPTS> ATANHF16_EXCEPTS{{
+ // (input, RZ output, RU offset, RD offset, RN offset)
+ // x = 0x1.a5cp-4, acoshf16(x) = 0x1.a74p-4 (RZ)
+ {0x2E97, 0x2E9D, 1, 0, 0},
+ // x = -0x1.a5cp-4, acoshf16(x) = -0x1.a74p-4 (RZ)
+ {0xAE97, 0xAE9D, 0, 1, 0},
+}};
+
LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
@@ -45,6 +55,10 @@ LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
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 0.10
if (LIBC_UNLIKELY(x_abs <= 0x2e66U)) {
// The Taylor expansion of atanh(x) is:
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