diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt index 366e4d34294d1..bdf010876910b 100644 --- a/libc/config/linux/x86_64/entrypoints.txt +++ b/libc/config/linux/x86_64/entrypoints.txt @@ -642,6 +642,7 @@ endif() if(LIBC_TYPES_HAS_FLOAT16) list(APPEND TARGET_LIBM_ENTRYPOINTS # math.h C23 _Float16 entrypoints + libc.src.math.asinf16 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 8548e4a5773bc..3e45e3e618abb 100644 --- a/libc/docs/headers/math/index.rst +++ b/libc/docs/headers/math/index.rst @@ -256,7 +256,7 @@ Higher Math Functions +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ | acospi | | | | | | 7.12.4.8 | F.10.1.8 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ -| asin | |check| | | | | | 7.12.4.2 | F.10.1.2 | +| asin | |check| | | | |check| | | 7.12.4.2 | F.10.1.2 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ | asinh | |check| | | | | | 7.12.5.2 | F.10.2.2 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ diff --git a/libc/include/math.yaml b/libc/include/math.yaml index 3a660a59d3605..b98bc55f6cc53 100644 --- a/libc/include/math.yaml +++ b/libc/include/math.yaml @@ -32,6 +32,13 @@ functions: return_type: float arguments: - type: float + - name: asinf16 + standards: + - stdc + return_type: _Float16 + arguments: + - type: _Float16 + guard: LIBC_TYPES_HAS_FLOAT16 - name: asinhf standards: - stdc diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt index fe5ebd793b40a..82551a4b57f45 100644 --- a/libc/src/math/CMakeLists.txt +++ b/libc/src/math/CMakeLists.txt @@ -47,6 +47,8 @@ add_math_entrypoint_object(acoshf) add_math_entrypoint_object(asin) add_math_entrypoint_object(asinf) +add_math_entrypoint_object(asinf16) + add_math_entrypoint_object(asinh) add_math_entrypoint_object(asinhf) diff --git a/libc/src/math/asinf16.h b/libc/src/math/asinf16.h new file mode 100644 index 0000000000000..f16647ec2a6f9 --- /dev/null +++ b/libc/src/math/asinf16.h @@ -0,0 +1,21 @@ +//===-- Implementation header for asinf16 -----------------------*- 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_ASINF16_H +#define LLVM_LIBC_SRC_MATH_ASINF16_H + +#include "src/__support/macros/config.h" +#include "src/__support/macros/properties/types.h" + +namespace LIBC_NAMESPACE_DECL { + +float16 asinf16(float16 x); + +} // namespace LIBC_NAMESPACE_DECL + +#endif // LLVM_LIBC_SRC_MATH_ASINF16_H diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt index 0e57051807b33..cf77987ff3add 100644 --- a/libc/src/math/generic/CMakeLists.txt +++ b/libc/src/math/generic/CMakeLists.txt @@ -4598,6 +4598,25 @@ add_entrypoint_object( ${libc_opt_high_flag} ) +add_entrypoint_object( + asinf16 + SRCS + asinf16.cpp + HDRS + ../asinf16.h + DEPENDS + 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 + libc.src.__support.FPUtil.sqrt + libc.src.__support.macros.optimization + libc.src.__support.macros.properties.types +) + add_entrypoint_object( acosf SRCS diff --git a/libc/src/math/generic/asinf16.cpp b/libc/src/math/generic/asinf16.cpp new file mode 100644 index 0000000000000..518c384a61530 --- /dev/null +++ b/libc/src/math/generic/asinf16.cpp @@ -0,0 +1,133 @@ +//===-- Half-precision asinf16(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/asinf16.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" +#include "src/__support/FPUtil/multiply_add.h" +#include "src/__support/FPUtil/sqrt.h" +#include "src/__support/macros/optimization.h" + +namespace LIBC_NAMESPACE_DECL { + +// Generated by Sollya using the following command: +// > round(pi/2, D, RN); +static constexpr float PI_2 = 0x1.921fb54442d18p0f; + +LLVM_LIBC_FUNCTION(float16, asinf16, (float16 x)) { + using FPBits = fputil::FPBits; + FPBits xbits(x); + + uint16_t x_u = xbits.uintval(); + uint16_t x_abs = x_u & 0x7fff; + float xf = x; + + // |x| > 0x1p0, |x| > 1, or x is NaN. + if (LIBC_UNLIKELY(x_abs > 0x3c00)) { + // asinf16(NaN) = NaN + if (xbits.is_nan()) { + if (xbits.is_signaling_nan()) { + fputil::raise_except_if_required(FE_INVALID); + return FPBits::quiet_nan().get_val(); + } + + return x; + } + + // 1 < |x| <= +/-inf + fputil::raise_except_if_required(FE_INVALID); + fputil::set_errno_if_required(EDOM); + + return FPBits::quiet_nan().get_val(); + } + + float xsq = xf * xf; + + // |x| <= 0x1p-1, |x| <= 0.5 + if (x_abs <= 0x3800) { + // asinf16(+/-0) = +/-0 + if (LIBC_UNLIKELY(x_abs == 0)) + return x; + + // Exhaustive tests show that, + // for |x| <= 0x1.878p-9, when: + // x > 0, and rounding upward, or + // x < 0, and rounding downward, then, + // asin(x) = x * 2^-11 + x + // else, in other rounding modes, + // asin(x) = x + if (LIBC_UNLIKELY(x_abs <= 0x1a1e)) { + int rounding = fputil::quick_get_round(); + + if ((xbits.is_pos() && rounding == FE_UPWARD) || + (xbits.is_neg() && rounding == FE_DOWNWARD)) + return fputil::cast(fputil::multiply_add(xf, 0x1.0p-11f, xf)); + return x; + } + + // Degree-6 minimax odd polynomial of asin(x) generated by Sollya with: + // > P = fpminimax(asin(x)/x, [|0, 2, 4, 6, 8|], [|SG...|], [0, 0.5]); + float result = + fputil::polyeval(xsq, 0x1.000002p0f, 0x1.554c2ap-3f, 0x1.3541ccp-4f, + 0x1.43b2d6p-5f, 0x1.a0d73ep-5f); + return fputil::cast(xf * result); + } + + // When |x| > 0.5, assume that 0.5 < |x| <= 1, + // + // Step-by-step range-reduction proof: + // 1: Let y = asin(x), such that, x = sin(y) + // 2: From complimentary angle identity: + // x = sin(y) = cos(pi/2 - y) + // 3: Let z = pi/2 - y, such that x = cos(z) + // 4: From double angle formula; cos(2A) = 1 - sin^2(A): + // z = 2A, z/2 = A + // cos(z) = 1 - 2 * sin^2(z/2) + // 5: Make sin(z/2) subject of the formula: + // sin(z/2) = sqrt((1 - cos(z))/2) + // 6: Recall [3]; x = cos(z). Therefore: + // sin(z/2) = sqrt((1 - x)/2) + // 7: Let u = (1 - x)/2 + // 8: Therefore: + // asin(sqrt(u)) = z/2 + // 2 * asin(sqrt(u)) = z + // 9: Recall [3], z = pi/2 - y. Therefore: + // y = pi/2 - z + // y = pi/2 - 2 * asin(sqrt(u)) + // 10: Recall [1], y = asin(x). Therefore: + // asin(x) = pi/2 - 2 * asin(sqrt(u)) + // + // WHY? + // 11: Recall [7], u = (1 - x)/2 + // 12: Since 0.5 < x <= 1, therefore: + // 0 <= u <= 0.25 and 0 <= sqrt(u) <= 0.5 + // + // Hence, we can reuse the same [0, 0.5] domain polynomial approximation for + // Step [10] as `sqrt(u)` is in range. + + // 0x1p-1 < |x| <= 0x1p0, 0.5 < |x| <= 1.0 + float xf_abs = (xf < 0 ? -xf : xf); + float sign = (xbits.uintval() >> 15 == 1 ? -1.0 : 1.0); + float u = fputil::multiply_add(-0.5f, xf_abs, 0.5f); + float u_sqrt = fputil::sqrt(u); + + // Degree-6 minimax odd polynomial of asin(x) generated by Sollya with: + // > P = fpminimax(asin(x)/x, [|0, 2, 4, 6, 8|], [|SG...|], [0, 0.5]); + float asin_sqrt_u = + u_sqrt * fputil::polyeval(u, 0x1.000002p0f, 0x1.554c2ap-3f, + 0x1.3541ccp-4f, 0x1.43b2d6p-5f, 0x1.a0d73ep-5f); + + return fputil::cast(sign * + fputil::multiply_add(-2.0f, asin_sqrt_u, PI_2)); +} + +} // namespace LIBC_NAMESPACE_DECL diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt index bbcdf2363c1e2..7af20dcaab4bd 100644 --- a/libc/test/src/math/CMakeLists.txt +++ b/libc/test/src/math/CMakeLists.txt @@ -2186,6 +2186,17 @@ add_fp_unittest( libc.src.__support.FPUtil.fp_bits ) +add_fp_unittest( + asinf16_test + NEED_MPFR + SUITE + libc-math-unittests + SRCS + asinf16_test.cpp + DEPENDS + libc.src.math.asinf16 +) + add_fp_unittest( acosf_test NEED_MPFR diff --git a/libc/test/src/math/asinf16_test.cpp b/libc/test/src/math/asinf16_test.cpp new file mode 100644 index 0000000000000..9593cad16ac77 --- /dev/null +++ b/libc/test/src/math/asinf16_test.cpp @@ -0,0 +1,42 @@ +//===-- Exhaustive test for asinf16 ---------------------------------------===// +// +// 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/asinf16.h" +#include "test/UnitTest/FPMatcher.h" +#include "test/UnitTest/Test.h" +#include "utils/MPFRWrapper/MPFRUtils.h" + +using LlvmLibcAsinf16Test = LIBC_NAMESPACE::testing::FPTest; + +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(LlvmLibcAsinf16Test, PositiveRange) { + for (uint16_t v = POS_START; v <= POS_STOP; ++v) { + float16 x = FPBits(v).get_val(); + + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Asin, x, + LIBC_NAMESPACE::asinf16(x), 0.5); + } +} + +TEST_F(LlvmLibcAsinf16Test, NegativeRange) { + for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) { + float16 x = FPBits(v).get_val(); + + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Asin, x, + LIBC_NAMESPACE::asinf16(x), 0.5); + } +} diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt index e4501eb75fa48..43a580ac6b894 100644 --- a/libc/test/src/math/smoke/CMakeLists.txt +++ b/libc/test/src/math/smoke/CMakeLists.txt @@ -3954,6 +3954,17 @@ add_fp_unittest( libc.src.__support.FPUtil.fp_bits ) +add_fp_unittest( + asinf16_test + SUITE + libc-math-smoke-tests + SRCS + asinf16_test.cpp + DEPENDS + libc.src.errno.errno + libc.src.math.asinf16 +) + add_fp_unittest( acosf_test SUITE diff --git a/libc/test/src/math/smoke/asinf16_test.cpp b/libc/test/src/math/smoke/asinf16_test.cpp new file mode 100644 index 0000000000000..9f675b08319c0 --- /dev/null +++ b/libc/test/src/math/smoke/asinf16_test.cpp @@ -0,0 +1,42 @@ +//===-- Unittests for asinf16 ---------------------------------------------===// +// +// +// 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/asinf16.h" +#include "test/UnitTest/FPMatcher.h" +#include "test/UnitTest/Test.h" + +using LlvmLibcAsinf16Test = LIBC_NAMESPACE::testing::FPTest; + +TEST_F(LlvmLibcAsinf16Test, SpecialNumbers) { + LIBC_NAMESPACE::libc_errno = 0; + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::asinf16(aNaN)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::asinf16(sNaN), FE_INVALID); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ(zero, LIBC_NAMESPACE::asinf16(zero)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::asinf16(neg_zero)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::asinf16(inf)); + EXPECT_MATH_ERRNO(EDOM); + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::asinf16(neg_inf)); + EXPECT_MATH_ERRNO(EDOM); + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::asinf16(2.0f)); + EXPECT_MATH_ERRNO(EDOM); + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::asinf16(-2.0f)); + EXPECT_MATH_ERRNO(EDOM); +}