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[libc][math][c23] Add tanpif16 function (#115183)
- Implementation of `tan` for 16-bit floating point inputs scaled by pi. i.e,. `tanpif16()` - Implementation of Tanpi in MPFRWrapper for MPFR versions < 4.2 - Exhaustive tests for `tanpif16()`
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+304
-3
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15 files changed

+304
-3
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‎libc/config/linux/x86_64/entrypoints.txt

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@@ -702,6 +702,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
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libc.src.math.sinpif16
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libc.src.math.sqrtf16
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libc.src.math.tanhf16
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libc.src.math.tanpif16
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libc.src.math.totalorderf16
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libc.src.math.totalordermagf16
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libc.src.math.truncf16

‎libc/docs/math/index.rst

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@@ -350,7 +350,7 @@ Higher Math Functions
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| tanh | |check| | | | |check| | | 7.12.5.6 | F.10.2.6 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| tanpi | | | | | | 7.12.4.14 | F.10.1.14 |
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| tanpi | | | | |check| | | 7.12.4.14 | F.10.1.14 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| tgamma | | | | | | 7.12.8.4 | F.10.5.4 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

‎libc/newhdrgen/yaml/math.yaml

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@@ -2416,6 +2416,13 @@ functions:
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arguments:
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- type: _Float16
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guard: LIBC_TYPES_HAS_FLOAT16
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- name: tanpif16
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standards:
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- stdc
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return_type: _Float16
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arguments:
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- type: _Float16
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guard: LIBC_TYPES_HAS_FLOAT16
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- name: totalorder
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standards:
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- stdc

‎libc/src/math/CMakeLists.txt

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@@ -503,6 +503,7 @@ add_math_entrypoint_object(tanf)
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add_math_entrypoint_object(tanh)
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add_math_entrypoint_object(tanhf)
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add_math_entrypoint_object(tanhf16)
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add_math_entrypoint_object(tanpif16)
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add_math_entrypoint_object(tgamma)
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add_math_entrypoint_object(tgammaf)

‎libc/src/math/cospif16.h

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@@ -18,4 +18,4 @@ float16 cospif16(float16 x);
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} // namespace LIBC_NAMESPACE_DECL
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#endif // LLVM_LIBC_SRC_MATH_SINPIF16_H
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#endif // LLVM_LIBC_SRC_MATH_COSPIF16_H

‎libc/src/math/generic/CMakeLists.txt

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@@ -620,6 +620,26 @@ add_entrypoint_object(
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-O3
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)
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add_entrypoint_object(
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tanpif16
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SRCS
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tanpif16.cpp
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HDRS
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../tanpif16.h
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DEPENDS
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.sincosf16_utils
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libc.hdr.errno_macros
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libc.hdr.fenv_macros
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libc.src.__support.FPUtil.cast
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libc.src.__support.FPUtil.fenv_impl
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libc.src.__support.FPUtil.fp_bits
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libc.src.__support.FPUtil.except_value_utils
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libc.src.__support.FPUtil.multiply_add
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libc.src.__support.macros.optimization
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COMPILE_OPTIONS
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-O3
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)
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add_entrypoint_object(
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fabs
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SRCS

‎libc/src/math/generic/cospif16.cpp

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@@ -37,7 +37,7 @@ LLVM_LIBC_FUNCTION(float16, cospif16, (float16 x)) {
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// k = round(x * 32)
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// y = x * 32 - k
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//
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// Once k and y are computed, we then deduce the answer by the sine of sum
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// Once k and y are computed, we then deduce the answer by the cosine of sum
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// formula:
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// cos(x * pi) = cos((k + y) * pi/32)
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// = cos(k * pi/32) * cos(y * pi/32) +

‎libc/src/math/generic/tanpif16.cpp

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//===-- Half-precision tanpif function ------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/math/tanpif16.h"
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#include "hdr/errno_macros.h"
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#include "hdr/fenv_macros.h"
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#include "sincosf16_utils.h"
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#include "src/__support/FPUtil/FEnvImpl.h"
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#include "src/__support/FPUtil/FPBits.h"
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#include "src/__support/FPUtil/cast.h"
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#include "src/__support/FPUtil/except_value_utils.h"
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#include "src/__support/FPUtil/multiply_add.h"
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#include "src/__support/macros/optimization.h"
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namespace LIBC_NAMESPACE_DECL {
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constexpr size_t N_EXCEPTS = 21;
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constexpr fputil::ExceptValues<float16, N_EXCEPTS> TANF16_EXCEPTS{{
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// (input, RZ output, RU offset, RD offset, RN offset)
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{0x07f2, 0x0e3d, 1, 0, 0}, {0x086a, 0x0eee, 1, 0, 1},
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{0x08db, 0x0fa0, 1, 0, 0}, {0x094c, 0x1029, 1, 0, 0},
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{0x0b10, 0x118c, 1, 0, 0}, {0x1ce0, 0x23a8, 1, 0, 1},
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{0x1235, 0x18e0, 1, 0, 0}, {0x2579, 0x2c4e, 1, 0, 0},
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{0x28b2, 0x2f68, 1, 0, 1}, {0x2a43, 0x30f4, 1, 0, 1},
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{0x31b7, 0x3907, 1, 0, 0}, {0x329d, 0x3a12, 1, 0, 1},
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{0x34f1, 0x3dd7, 1, 0, 0}, {0x3658, 0x41ee, 1, 0, 0},
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{0x38d4, 0xc1ee, 0, 1, 0}, {0x3d96, 0x41ee, 1, 0, 0},
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{0x3e6a, 0xc1ee, 0, 1, 0}, {0x40cb, 0x41ee, 1, 0, 0},
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{0x4135, 0xc1ee, 0, 1, 0}, {0x42cb, 0x41ee, 1, 0, 0},
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{0x4335, 0xc1ee, 0, 1, 0},
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}};
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LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
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using FPBits = typename fputil::FPBits<float16>;
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FPBits xbits(x);
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uint16_t x_u = xbits.uintval();
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uint16_t x_abs = x_u & 0x7fff;
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// Handle exceptional values
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if (LIBC_UNLIKELY(x_abs <= 0x4335)) {
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if (LIBC_UNLIKELY(x_abs == 0U))
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return x;
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bool x_sign = x_u >> 15;
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if (auto r = TANF16_EXCEPTS.lookup_odd(x_abs, x_sign);
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LIBC_UNLIKELY(r.has_value()))
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return r.value();
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}
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// Numbers greater or equal to 2^10 are integers, or infinity, or NaN
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if (LIBC_UNLIKELY(x_abs >= 0x6400)) {
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// Check for NaN or infinity values
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if (LIBC_UNLIKELY(x_abs >= 0x7c00)) {
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if (x_abs == 0x7c00) {
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fputil::set_errno_if_required(EDOM);
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fputil::raise_except_if_required(FE_INVALID);
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}
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return x + FPBits::quiet_nan().get_val();
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}
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return FPBits::zero(xbits.sign()).get_val();
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}
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// Range reduction:
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// For |x| > 1/32, we perform range reduction as follows:
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// Find k and y such that:
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// x = (k + y) * 1/32
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// k is an integer
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// |y| < 0.5
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//
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// This is done by performing:
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// k = round(x * 32)
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// y = x * 32 - k
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//
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// Once k and y are computed, we then deduce the answer by tthe formula:
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// tan(x) = sin(x) / cos(x)
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// = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k)
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float xf = x;
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float sin_k, cos_k, sin_y, cosm1_y;
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sincospif16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
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if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0)) {
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fputil::set_errno_if_required(EDOM);
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fputil::raise_except_if_required(FE_DIVBYZERO);
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int16_t x_mp5_u = static_cast<int16_t>(x - 0.5);
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return ((x_mp5_u & 0x1) ? -1 : 1) * FPBits::inf().get_val();
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}
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using fputil::multiply_add;
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return fputil::cast<float16>(
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multiply_add(sin_y, cos_k, multiply_add(cosm1_y, sin_k, sin_k)) /
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multiply_add(sin_y, -sin_k, multiply_add(cosm1_y, cos_k, cos_k)));
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}
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} // namespace LIBC_NAMESPACE_DECL

‎libc/src/math/tanpif16.h

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//===-- Implementation header for tanpif16 ----------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_MATH_TANPIF16_H
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#define LLVM_LIBC_SRC_MATH_TANPIF16_H
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#include "src/__support/macros/config.h"
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#include "src/__support/macros/properties/types.h"
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namespace LIBC_NAMESPACE_DECL {
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float16 tanpif16(float16 x);
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} // namespace LIBC_NAMESPACE_DECL
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#endif // LLVM_LIBC_SRC_MATH_TANPIF16_H

‎libc/test/src/math/CMakeLists.txt

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@@ -168,6 +168,17 @@ add_fp_unittest(
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libc.src.__support.FPUtil.fp_bits
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)
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add_fp_unittest(
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tanpif16_test
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NEED_MPFR
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SUITE
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libc-math-unittests
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SRCS
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tanpif16_test.cpp
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DEPENDS
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libc.src.math.tanpif16
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)
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add_fp_unittest(
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fabs_test
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NEED_MPFR

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