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[libc][math][c23] Add atanhf16 C23 math function.
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11 files changed

+249
-4
lines changed

11 files changed

+249
-4
lines changed

‎libc/config/linux/x86_64/entrypoints.txt

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@@ -655,6 +655,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
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libc.src.math.asinf16
656656
libc.src.math.acosf16
657657
libc.src.math.acoshf16
658+
libc.src.math.atanhf16
658659
libc.src.math.canonicalizef16
659660
libc.src.math.ceilf16
660661
libc.src.math.copysignf16

‎libc/docs/headers/math/index.rst

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@@ -267,7 +267,7 @@ Higher Math Functions
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| atan2pi | | | | | | 7.12.4.11 | F.10.1.11 |
269269
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
270-
| atanh | |check| | | | | | 7.12.5.3 | F.10.2.3 |
270+
| atanh | |check| | | | |check| | | 7.12.5.3 | F.10.2.3 |
271271
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
272272
| atanpi | | | | | | 7.12.4.10 | F.10.1.10 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

‎libc/include/math.yaml

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@@ -98,6 +98,13 @@ functions:
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return_type: float
9999
arguments:
100100
- type: float
101+
- name: atanhf16
102+
standards:
103+
- stdc
104+
return_type: _Float16
105+
arguments:
106+
- type: _Float16
107+
guard: LIBC_TYPES_HAS_FLOAT16
101108
- name: canonicalize
102109
standards:
103110
- stdc

‎libc/src/math/CMakeLists.txt

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@@ -64,6 +64,7 @@ add_math_entrypoint_object(atan2l)
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6565
add_math_entrypoint_object(atanh)
6666
add_math_entrypoint_object(atanhf)
67+
add_math_entrypoint_object(atanhf16)
6768

6869
add_math_entrypoint_object(canonicalize)
6970
add_math_entrypoint_object(canonicalizef)

‎libc/src/math/atanhf16.h

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@@ -0,0 +1,21 @@
1+
//===-- Implementation header for atanhf16 ----------------------*- C++ -*-===//
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//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
7+
//===----------------------------------------------------------------------===//
8+
9+
#ifndef LLVM_LIBC_SRC_MATH_ATANHF16_H
10+
#define LLVM_LIBC_SRC_MATH_ATANHF16_H
11+
12+
#include "src/__support/macros/config.h"
13+
#include "src/__support/macros/properties/types.h"
14+
15+
namespace LIBC_NAMESPACE_DECL {
16+
17+
float16 atanhf16(float16 x);
18+
19+
} // namespace LIBC_NAMESPACE_DECL
20+
21+
#endif // LLVM_LIBC_SRC_MATH_ATANHF16_H

‎libc/src/math/generic/CMakeLists.txt

Lines changed: 12 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -3955,12 +3955,9 @@ add_entrypoint_object(
39553955
libc.hdr.errno_macros
39563956
libc.hdr.fenv_macros
39573957
libc.src.__support.FPUtil.cast
3958-
libc.src.__support.FPUtil.except_value_utils
3959-
libc.src.__support.FPUtil.fenv_impl
39603958
libc.src.__support.FPUtil.fp_bits
39613959
libc.src.__support.FPUtil.multiply_add
39623960
libc.src.__support.FPUtil.polyeval
3963-
libc.src.__support.FPUtil.sqrt
39643961
libc.src.__support.macros.optimization
39653962
libc.src.__support.macros.properties.types
39663963
)
@@ -3992,6 +3989,18 @@ add_entrypoint_object(
39923989
libc.src.__support.macros.optimization
39933990
)
39943991

3992+
add_entrypoint_object(
3993+
atanhf16
3994+
SRCS
3995+
atanhf16.cpp
3996+
HDRS
3997+
../atanhf16.h
3998+
DEPENDS
3999+
.explogxf
4000+
libc.src.__support.FPUtil.fp_bits
4001+
libc.src.__support.macros.optimization
4002+
)
4003+
39954004
add_object_library(
39964005
inv_trigf_utils
39974006
HDRS

‎libc/src/math/generic/atanhf16.cpp

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@@ -0,0 +1,86 @@
1+
//===-- Implementation of atanh(x) function -------------------------------===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#include "src/math/atanhf16.h"
10+
#include "explogxf.h"
11+
#include "hdr/errno_macros.h"
12+
#include "hdr/fenv_macros.h"
13+
#include "src/__support/FPUtil/FPBits.h"
14+
#include "src/__support/FPUtil/PolyEval.h"
15+
#include "src/__support/FPUtil/cast.h"
16+
#include "src/__support/FPUtil/multiply_add.h"
17+
#include "src/__support/common.h"
18+
#include "src/__support/macros/config.h"
19+
#include "src/__support/macros/optimization.h"
20+
21+
namespace LIBC_NAMESPACE_DECL {
22+
23+
LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) {
24+
using FPBits = typename fputil::FPBits<float16>;
25+
26+
FPBits xbits(x);
27+
Sign sign = xbits.sign();
28+
uint16_t x_abs = xbits.abs().uintval();
29+
30+
if (LIBC_UNLIKELY(x_abs >= 0x3c00U)) {
31+
if (xbits.is_nan()) {
32+
return x;
33+
}
34+
// |x| == 1.0
35+
if (x_abs == 0x3c00U) {
36+
fputil::set_errno_if_required(ERANGE);
37+
fputil::raise_except_if_required(FE_DIVBYZERO);
38+
return FPBits::inf(sign).get_val();
39+
} else {
40+
fputil::set_errno_if_required(EDOM);
41+
fputil::raise_except_if_required(FE_INVALID);
42+
return FPBits::quiet_nan().get_val();
43+
}
44+
}
45+
46+
// For |x| less than approximately 0.10
47+
if (LIBC_UNLIKELY(x_abs <= 0x2e66U)) {
48+
// The Taylor expansion of atanh(x) is:
49+
// atanh(x) = x + x^3/3 + x^5/5 + x^7/7 + x^9/9 + x^11/11
50+
// = x * [1 + x^2/3 + x^4/5 + x^6/7 + x^8/9 + x^10/11]
51+
// When |x| < 0x0100U, this can be approximated by:
52+
// atanh(x) ≈ x + (1/3)*x^3
53+
if (LIBC_UNLIKELY(x_abs < 0x0100U)) {
54+
return static_cast<float16>(
55+
LIBC_UNLIKELY(x_abs == 0) ? x : (x + 0x1.555556p-2 * x * x * x));
56+
}
57+
58+
// For 0x0100U <= |x| <= 0x2e66U:
59+
// Let t = x^2.
60+
// Define P(t) ≈ (1/3)*t + (1/5)*t^2 + (1/7)*t^3 + (1/9)*t^4 + (1/11)*t^5.
61+
// The coefficients below were derived using Sollya:
62+
// > display = hexadecimal;
63+
// > round(1/3, SG, RN);
64+
// > round(1/5, SG, RN);
65+
// > round(1/7, SG, RN);
66+
// > round(1/9, SG, RN);
67+
// > round(1/11, SG, RN);
68+
// This yields:
69+
// 0x1.555556p-2
70+
// 0x1.99999ap-3
71+
// 0x1.24924ap-3
72+
// 0x1.c71c72p-4
73+
// 0x1.745d18p-4f
74+
// Thus, atanh(x) ≈ x * (1 + P(x^2)).
75+
float xf = x;
76+
float x2 = xf * xf;
77+
float pe = fputil::polyeval(x2, 0.0f, 0x1.555556p-2f, 0x1.99999ap-3f,
78+
0x1.24924ap-3f, 0x1.c71c72p-4f, 0x1.745d18p-4f);
79+
return static_cast<float16>(fputil::multiply_add(xf, pe, xf));
80+
}
81+
82+
float xf = x;
83+
return static_cast<float16>(0.5 * log_eval((xf + 1.0) / (xf - 1.0)));
84+
}
85+
86+
} // namespace LIBC_NAMESPACE_DECL

‎libc/test/src/math/CMakeLists.txt

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@@ -2132,6 +2132,17 @@ add_fp_unittest(
21322132
libc.src.__support.FPUtil.fp_bits
21332133
)
21342134

2135+
add_fp_unittest(
2136+
atanhf16_test
2137+
NEED_MPFR
2138+
SUITE
2139+
libc-math-unittests
2140+
SRCS
2141+
atanhf16_test.cpp
2142+
DEPENDS
2143+
libc.src.math.atanhf16
2144+
)
2145+
21352146
add_fp_unittest(
21362147
fmul_test
21372148
NEED_MPFR

‎libc/test/src/math/atanhf16_test.cpp

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@@ -0,0 +1,39 @@
1+
//===-- Unittests for atanhf16 --------------------------------------------===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#include "src/__support/FPUtil/FPBits.h"
10+
#include "src/errno/libc_errno.h"
11+
#include "src/math/atanhf16.h"
12+
#include "test/UnitTest/FPMatcher.h"
13+
#include "test/UnitTest/Test.h"
14+
#include "utils/MPFRWrapper/MPFRUtils.h"
15+
#include <stdint.h>
16+
17+
using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
18+
namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
19+
20+
static constexpr uint16_t POS_START = 0x0000U;
21+
static constexpr uint16_t POS_STOP = 0x3BFFU;
22+
static constexpr uint16_t NEG_START = 0xBBFFU;
23+
static constexpr uint16_t NEG_STOP = 0x8000U;
24+
25+
TEST_F(LlvmLibcAtanhf16Test, PositiveRange) {
26+
for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
27+
float16 x = FPBits(v).get_val();
28+
EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Atanh, x,
29+
LIBC_NAMESPACE::atanhf16(x), 0.5);
30+
}
31+
}
32+
33+
TEST_F(LlvmLibcAtanhf16Test, NegativeRange) {
34+
for (uint16_t v = NEG_START; v <= NEG_STOP; --v) {
35+
float16 x = FPBits(v).get_val();
36+
EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Atanh, x,
37+
LIBC_NAMESPACE::atanhf16(x), 0.5);
38+
}
39+
}

‎libc/test/src/math/smoke/CMakeLists.txt

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Original file line numberDiff line numberDiff line change
@@ -3934,6 +3934,18 @@ add_fp_unittest(
39343934
libc.src.__support.FPUtil.fp_bits
39353935
)
39363936

3937+
add_fp_unittest(
3938+
atanhf16_test
3939+
SUITE
3940+
libc-math-smoke-tests
3941+
SRCS
3942+
atanhf16_test.cpp
3943+
DEPENDS
3944+
libc.src.errno.errno
3945+
libc.src.math.atanhf16
3946+
libc.src.__support.FPUtil.fp_bits
3947+
)
3948+
39373949
add_fp_unittest(
39383950
asinhf_test
39393951
SUITE

‎libc/test/src/math/smoke/atanhf16_test.cpp

Lines changed: 58 additions & 0 deletions
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@@ -0,0 +1,58 @@
1+
//===-- Unittests for atanhf16 --------------------------------------------===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#include "src/__support/FPUtil/cast.h"
10+
#include "src/errno/libc_errno.h"
11+
#include "src/math/atanhf16.h"
12+
#include "test/UnitTest/FPMatcher.h"
13+
#include "test/UnitTest/Test.h"
14+
15+
using LlvmLibcAtanhf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
16+
17+
TEST_F(LlvmLibcAtanhf16Test, SpecialNumbers) {
18+
LIBC_NAMESPACE::libc_errno = 0;
19+
EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::atanhf16(aNaN));
20+
EXPECT_MATH_ERRNO(0);
21+
22+
EXPECT_FP_EQ_ALL_ROUNDING(zero, LIBC_NAMESPACE::atanhf16(zero));
23+
EXPECT_MATH_ERRNO(0);
24+
25+
EXPECT_FP_EQ_ALL_ROUNDING(
26+
-0.0f,
27+
LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-0.0f)));
28+
EXPECT_MATH_ERRNO(0);
29+
30+
EXPECT_FP_EQ_WITH_EXCEPTION(
31+
inf,
32+
LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(1.0f)),
33+
FE_DIVBYZERO);
34+
EXPECT_MATH_ERRNO(ERANGE);
35+
36+
EXPECT_FP_EQ_WITH_EXCEPTION(
37+
neg_inf,
38+
LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-1.0f)),
39+
FE_DIVBYZERO);
40+
EXPECT_MATH_ERRNO(ERANGE);
41+
42+
EXPECT_FP_IS_NAN_WITH_EXCEPTION(
43+
LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(2.0f)),
44+
FE_INVALID);
45+
EXPECT_MATH_ERRNO(EDOM);
46+
47+
EXPECT_FP_IS_NAN_WITH_EXCEPTION(
48+
LIBC_NAMESPACE::atanhf16(LIBC_NAMESPACE::fputil::cast<float16>(-2.0f)),
49+
FE_INVALID);
50+
EXPECT_MATH_ERRNO(EDOM);
51+
52+
EXPECT_FP_IS_NAN_WITH_EXCEPTION(LIBC_NAMESPACE::atanhf16(inf), FE_INVALID);
53+
EXPECT_MATH_ERRNO(EDOM);
54+
55+
EXPECT_FP_IS_NAN_WITH_EXCEPTION(LIBC_NAMESPACE::atanhf16(neg_inf),
56+
FE_INVALID);
57+
EXPECT_MATH_ERRNO(EDOM);
58+
}

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