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[libc][math][c23] Add sinf16 C23 math function (#116674)

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Co-authored-by: OverMighty <its.overmighty@gmail.com>
This commit is contained in:
wldfngrs
2024-12-03 21:08:46 +01:00
committed by GitHub
parent fc11b6790e
commit cd04653c4e
13 changed files with 299 additions and 7 deletions
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1
libc/config/linux/x86_64/entrypoints.txt
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@@ -700,6 +700,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
libc.src.math.scalbnf16
libc.src.math.setpayloadf16
libc.src.math.setpayloadsigf16
libc.src.math.sinf16
libc.src.math.sinhf16
libc.src.math.sinpif16
libc.src.math.sqrtf16

2
libc/docs/math/index.rst
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@@ -336,7 +336,7 @@ Higher Math Functions
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| rsqrt | | | | | | 7.12.7.9 | F.10.4.9 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| sin | |check| | |check| | | | | 7.12.4.6 | F.10.1.6 |
| sin | |check| | |check| | | |check| | | 7.12.4.6 | F.10.1.6 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| sincos | |check| | |check| | | | | | |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

7
libc/newhdrgen/yaml/math.yaml
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@@ -2339,6 +2339,13 @@ functions:
return_type: float
arguments:
- type: float
- name: sinf16
standards:
- stdc
return_type: _Float16
arguments:
- type: _Float16
guard: LIBC_TYPES_HAS_FLOAT16
- name: sinhf
standards:
- stdc

1
libc/src/math/CMakeLists.txt
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@@ -484,6 +484,7 @@ add_math_entrypoint_object(sincosf)
add_math_entrypoint_object(sin)
add_math_entrypoint_object(sinf)
add_math_entrypoint_object(sinf16)
add_math_entrypoint_object(sinpif)
add_math_entrypoint_object(sinpif16)

21
libc/src/math/generic/CMakeLists.txt
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@@ -498,6 +498,27 @@ add_entrypoint_object(
${libc_opt_high_flag}
)
add_entrypoint_object(
sinf16
SRCS
sinf16.cpp
HDRS
../sinf16.h
DEPENDS
.sincosf16_utils
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.except_value_utils
libc.src.__support.FPUtil.multiply_add
libc.src.__support.macros.optimization
libc.src.__support.macros.properties.types
COMPILE_OPTIONS
-O3
)
add_entrypoint_object(
sincos
SRCS

46
libc/src/math/generic/sincosf16_utils.h
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@@ -11,6 +11,7 @@
#include "src/__support/FPUtil/FPBits.h"
#include "src/__support/FPUtil/PolyEval.h"
#include "src/__support/FPUtil/cast.h"
#include "src/__support/FPUtil/nearest_integer.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
@@ -46,10 +47,31 @@ LIBC_INLINE int32_t range_reduction_sincospif16(float x, float &y) {
return static_cast<int32_t>(kf);
}
LIBC_INLINE void sincospif16_eval(float xf, float &sin_k, float &cos_k,
float &sin_y, float &cosm1_y) {
float y;
int32_t k = range_reduction_sincospif16(xf, y);
// Recall, range reduction:
// k = round(x * 32/pi)
// y = x * 32/pi - k
//
// The constant 0x1.45f306dc9c883p3 is 32/pi rounded to double-precision.
// 32/pi is generated by Sollya with the following commands:
// > display = hexadecimal;
// > round(32/pi, D, RN);
//
// The precision choice of 'double' is to minimize rounding errors
// in this initial scaling step, preserving enough bits so errors accumulated
// while computing the subtraction: y = x * 32/pi - round(x * 32/pi)
// are beyond the least-significant bit of single-precision used during
// further intermediate computation.
LIBC_INLINE int32_t range_reduction_sincosf16(float x, float &y) {
double prod = x * 0x1.45f306dc9c883p3;
double kf = fputil::nearest_integer(prod);
y = static_cast<float>(prod - kf);
return static_cast<int32_t>(kf);
}
static LIBC_INLINE void sincosf16_poly_eval(int32_t k, float y, float &sin_k,
float &cos_k, float &sin_y,
float &cosm1_y) {
sin_k = SIN_K_PI_OVER_32[k & 63];
cos_k = SIN_K_PI_OVER_32[(k + 16) & 63];
@@ -72,6 +94,22 @@ LIBC_INLINE void sincospif16_eval(float xf, float &sin_k, float &cos_k,
0x1.a6f7a2p-29f);
}
LIBC_INLINE void sincosf16_eval(float xf, float &sin_k, float &cos_k,
float &sin_y, float &cosm1_y) {
float y;
int32_t k = range_reduction_sincosf16(xf, y);
sincosf16_poly_eval(k, y, sin_k, cos_k, sin_y, cosm1_y);
}
LIBC_INLINE void sincospif16_eval(float xf, float &sin_k, float &cos_k,
float &sin_y, float &cosm1_y) {
float y;
int32_t k = range_reduction_sincospif16(xf, y);
sincosf16_poly_eval(k, y, sin_k, cos_k, sin_y, cosm1_y);
}
} // namespace LIBC_NAMESPACE_DECL
#endif // LLVM_LIBC_SRC_MATH_GENERIC_SINCOSF16_UTILS_H

108
libc/src/math/generic/sinf16.cpp Normal file
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@@ -0,0 +1,108 @@
//===-- Half-precision sin(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/sinf16.h"
#include "hdr/errno_macros.h"
#include "hdr/fenv_macros.h"
#include "sincosf16_utils.h"
#include "src/__support/FPUtil/FEnvImpl.h"
#include "src/__support/FPUtil/FPBits.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/macros/optimization.h"
namespace LIBC_NAMESPACE_DECL {
constexpr size_t N_EXCEPTS = 4;
constexpr fputil::ExceptValues<float16, N_EXCEPTS> SINF16_EXCEPTS{{
// (input, RZ output, RU offset, RD offset, RN offset)
{0x2b45, 0x2b43, 1, 0, 1},
{0x585c, 0x3ba3, 1, 0, 1},
{0x5cb0, 0xbbff, 0, 1, 0},
{0x51f5, 0xb80f, 0, 1, 0},
}};
LLVM_LIBC_FUNCTION(float16, sinf16, (float16 x)) {
using FPBits = fputil::FPBits<float16>;
FPBits xbits(x);
uint16_t x_u = xbits.uintval();
uint16_t x_abs = x_u & 0x7fff;
float xf = x;
// Range reduction:
// For |x| > pi/32, we perform range reduction as follows:
// Find k and y such that:
// x = (k + y) * pi/32
// k is an integer, |y| < 0.5
//
// This is done by performing:
// k = round(x * 32/pi)
// y = x * 32/pi - k
//
// Once k and y are computed, we then deduce the answer by the sine of sum
// formula:
// sin(x) = sin((k + y) * pi/32)
// = sin(k * pi/32) * cos(y * pi/32) +
// sin(y * pi/32) * cos(k * pi/32)
// Handle exceptional values
if (LIBC_UNLIKELY(x_abs == 0x585c || x_abs == 0x5cb0 || x_abs == 0x51f5 ||
x_abs == 0x2b45)) {
bool x_sign = x_u >> 15;
if (auto r = SINF16_EXCEPTS.lookup_odd(x_abs, x_sign);
LIBC_UNLIKELY(r.has_value()))
return r.value();
}
int rounding = fputil::quick_get_round();
// Exhaustive tests show that for |x| <= 0x1.f4p-11, 1ULP rounding errors
// occur. To fix this, the following apply:
if (LIBC_UNLIKELY(x_abs <= 0x13d0)) {
// sin(+/-0) = +/-0
if (LIBC_UNLIKELY(x_abs == 0U))
return x;
// When x > 0, and rounding upward, sin(x) == x.
// When x < 0, and rounding downward, sin(x) == x.
if ((rounding == FE_UPWARD && xbits.is_pos()) ||
(rounding == FE_DOWNWARD && xbits.is_neg()))
return x;
// When x < 0, and rounding upward, sin(x) == (x - 1ULP)
if (rounding == FE_UPWARD && xbits.is_neg()) {
x_u--;
return FPBits(x_u).get_val();
}
}
if (xbits.is_inf_or_nan()) {
if (xbits.is_inf()) {
fputil::set_errno_if_required(EDOM);
fputil::raise_except_if_required(FE_INVALID);
}
return x + FPBits::quiet_nan().get_val();
}
float sin_k, cos_k, sin_y, cosm1_y;
sincosf16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
if (LIBC_UNLIKELY(sin_y == 0 && sin_k == 0))
return FPBits::zero(xbits.sign()).get_val();
// Since, cosm1_y = cos_y - 1, therfore:
// sin(x) = cos_k * sin_y + sin_k + (cosm1_y * sin_k)
return fputil::cast<float16>(fputil::multiply_add(
sin_y, cos_k, fputil::multiply_add(cosm1_y, sin_k, sin_k)));
}
} // namespace LIBC_NAMESPACE_DECL

4
libc/src/math/generic/tanpif16.cpp
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@@ -21,7 +21,7 @@ namespace LIBC_NAMESPACE_DECL {
constexpr size_t N_EXCEPTS = 21;
constexpr fputil::ExceptValues<float16, N_EXCEPTS> TANF16_EXCEPTS{{
constexpr fputil::ExceptValues<float16, N_EXCEPTS> TANPIF16_EXCEPTS{{
// (input, RZ output, RU offset, RD offset, RN offset)
{0x07f2, 0x0e3d, 1, 0, 0}, {0x086a, 0x0eee, 1, 0, 1},
{0x08db, 0x0fa0, 1, 0, 0}, {0x094c, 0x1029, 1, 0, 0},
@@ -49,7 +49,7 @@ LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
return x;
bool x_sign = x_u >> 15;
if (auto r = TANF16_EXCEPTS.lookup_odd(x_abs, x_sign);
if (auto r = TANPIF16_EXCEPTS.lookup_odd(x_abs, x_sign);
LIBC_UNLIKELY(r.has_value()))
return r.value();
}

21
libc/src/math/sinf16.h Normal file
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@@ -0,0 +1,21 @@
//===-- Implementation header for sinf16 ------------------------*- 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_SINF16_H
#define LLVM_LIBC_SRC_MATH_SINF16_H
#include "src/__support/macros/config.h"
#include "src/__support/macros/properties/types.h"
namespace LIBC_NAMESPACE_DECL {
float16 sinf16(float16 x);
} // namespace LIBC_NAMESPACE_DECL
#endif // LLVM_LIBC_SRC_MATH_SINF16_H

11
libc/test/src/math/CMakeLists.txt
View File

@@ -85,6 +85,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
add_fp_unittest(
sinf16_test
NEED_MPFR
SUITE
libc-math-unittests
SRCS
sinf16_test.cpp
DEPENDS
libc.src.math.sinf16
)
add_fp_unittest(
sinpif_test
NEED_MPFR

40
libc/test/src/math/sinf16_test.cpp Normal file
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@@ -0,0 +1,40 @@
//===-- Exhaustive test for sinf16 ----------------------------------------===//
//
// 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/sinf16.h"
#include "test/UnitTest/FPMatcher.h"
#include "test/UnitTest/Test.h"
#include "utils/MPFRWrapper/MPFRUtils.h"
using LlvmLibcSinf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
// Range: [0, Inf]
static constexpr uint16_t POS_START = 0x0000U;
static constexpr uint16_t POS_STOP = 0x7c00U;
// Range: [-Inf, 0]
static constexpr uint16_t NEG_START = 0x8000U;
static constexpr uint16_t NEG_STOP = 0xfc00U;
TEST_F(LlvmLibcSinf16Test, PositiveRange) {
for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
float16 x = FPBits(v).get_val();
EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Sin, x,
LIBC_NAMESPACE::sinf16(x), 0.5);
}
}
TEST_F(LlvmLibcSinf16Test, NegativeRange) {
for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
float16 x = FPBits(v).get_val();
EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Sin, x,
LIBC_NAMESPACE::sinf16(x), 0.5);
}
}

11
libc/test/src/math/smoke/CMakeLists.txt
View File

@@ -49,6 +49,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
add_fp_unittest(
sinf16_test
SUITE
libc-math-smoke-tests
SRCS
sinf16_test.cpp
DEPENDS
libc.src.errno.errno
libc.src.math.sinf16
)
add_fp_unittest(
sinpif_test
SUITE

33
libc/test/src/math/smoke/sinf16_test.cpp Normal file
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@@ -0,0 +1,33 @@
//===-- Unittests for sinf16 ----------------------------------------------===//
//
// 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/errno/libc_errno.h"
#include "src/math/sinf16.h"
#include "test/UnitTest/FPMatcher.h"
#include "test/UnitTest/Test.h"
using LlvmLibcSinf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
TEST_F(LlvmLibcSinf16Test, SpecialNumbers) {
LIBC_NAMESPACE::libc_errno = 0;
EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::sinf16(aNaN));
EXPECT_MATH_ERRNO(0);
EXPECT_FP_EQ(zero, LIBC_NAMESPACE::sinf16(zero));
EXPECT_MATH_ERRNO(0);
EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::sinf16(neg_zero));
EXPECT_MATH_ERRNO(0);
EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::sinf16(inf));
EXPECT_MATH_ERRNO(EDOM);
EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::sinf16(neg_inf));
EXPECT_MATH_ERRNO(EDOM);
}