[libc][math][c23] Add atanhf16 C23 math function. #132612
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@llvm/pr-subscribers-libc Author: Harrison Hao (harrisonGPU) ChangesImplementation of atanhf16 function for 16-bit inputs. Full diff: https://github.com/llvm/llvm-project/pull/132612.diff 11 Files Affected:
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index ac281e8d39066..f92f6f234bfdc 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -655,6 +655,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.asinf16
libc.src.math.acosf16
libc.src.math.acoshf16
+ 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 16903a40c03fa..82a552a6568bf 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 bd29eb0213c4f..627aae9de5942 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -98,6 +98,13 @@ 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 92c80a1053c9e..72d2e16622d1a 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -64,6 +64,7 @@ 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 77c6244c5e5da..9f3abc0cb1530 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -3955,12 +3955,9 @@ add_entrypoint_object(
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.FPUtil.sqrt
libc.src.__support.macros.optimization
libc.src.__support.macros.properties.types
)
@@ -3992,6 +3989,18 @@ add_entrypoint_object(
libc.src.__support.macros.optimization
)
+add_entrypoint_object(
+ atanhf16
+ SRCS
+ atanhf16.cpp
+ HDRS
+ ../atanhf16.h
+ DEPENDS
+ .explogxf
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.macros.optimization
+)
+
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 6ca4163f07949..371fb0e25a6cf 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 660b68687d63c..aae8140f93c5b 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);
+}
|
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harrisonGPU
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Hi @jhuber6 @overmighty @lntue Could you please review this PR, if you have time. :-) |
lntue
reviewed
Mar 26, 2025
libc/test/src/math/atanhf16_test.cpp
Outdated
|
|
||
| // Range for positive numbers: [0, 1) | ||
| static constexpr uint16_t POS_START = 0x0000U; | ||
| static constexpr uint16_t POS_STOP = 0x3C00; |
There was a problem hiding this comment.
I think our MPFR testing now can take care of inf/nan cases. So you should be able to test for the entire range.
There was a problem hiding this comment.
Okay, I have updated it. :-)
lntue
reviewed
Mar 26, 2025
lntue
reviewed
Mar 26, 2025
overmighty
requested changes
Mar 26, 2025
libc/src/math/generic/atanhf16.cpp
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| // 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 |
There was a problem hiding this comment.
This is too verbose in my opinion.
There was a problem hiding this comment.
I have updated it, what do you think about it? @overmighty
libc/src/math/generic/atanhf16.cpp
Outdated
| } | ||
|
|
||
| float xf = x; | ||
| return static_cast<float16>(0.5 * log_eval((xf + 1.0) / (xf - 1.0))); |
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Suggested change
| 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))); |
There was a problem hiding this comment.
Okay, I have updated it.
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Implementation of atanhf16 function for 16-bit inputs.
Closes: #132209