diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt index 7e549607716c0..4ae704ec5af38 100644 --- a/libc/config/linux/x86_64/entrypoints.txt +++ b/libc/config/linux/x86_64/entrypoints.txt @@ -718,6 +718,7 @@ if(LIBC_TYPES_HAS_FLOAT16) libc.src.math.sinhf16 libc.src.math.sinpif16 libc.src.math.sqrtf16 + libc.src.math.tanf16 libc.src.math.tanhf16 libc.src.math.tanpif16 libc.src.math.totalorderf16 diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst index 2808165ad539b..8548e4a5773bc 100644 --- a/libc/docs/headers/math/index.rst +++ b/libc/docs/headers/math/index.rst @@ -346,7 +346,7 @@ Higher Math Functions +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ | sqrt | |check| | |check| | |check| | |check| | |check| | 7.12.7.10 | F.10.4.10 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ -| tan | |check| | |check| | | | | 7.12.4.7 | F.10.1.7 | +| tan | |check| | |check| | | |check| | | 7.12.4.7 | F.10.1.7 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ | tanh | |check| | | | |check| | | 7.12.5.6 | F.10.2.6 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ diff --git a/libc/include/math.yaml b/libc/include/math.yaml index 3b8caec66bbfd..14e527f4a6f3d 100644 --- a/libc/include/math.yaml +++ b/libc/include/math.yaml @@ -2417,6 +2417,13 @@ functions: return_type: float arguments: - type: float + - name: tanf16 + standards: + - stdc + return_type: _Float16 + arguments: + - type: _Float16 + guard: LIBC_TYPES_HAS_FLOAT16 - name: tanhf standards: - stdc diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt index e4e2c49642f2d..fe5ebd793b40a 100644 --- a/libc/src/math/CMakeLists.txt +++ b/libc/src/math/CMakeLists.txt @@ -501,6 +501,7 @@ add_math_entrypoint_object(sqrtf128) add_math_entrypoint_object(tan) add_math_entrypoint_object(tanf) +add_math_entrypoint_object(tanf16) add_math_entrypoint_object(tanh) add_math_entrypoint_object(tanhf) diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt index b3d4612915197..824a161df1b19 100644 --- a/libc/src/math/generic/CMakeLists.txt +++ b/libc/src/math/generic/CMakeLists.txt @@ -662,6 +662,25 @@ add_entrypoint_object( ${libc_opt_high_flag} ) +add_entrypoint_object( + tanf16 + SRCS + tanf16.cpp + HDRS + ../tanf16.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 +) + add_entrypoint_object( tanpif16 SRCS diff --git a/libc/src/math/generic/sincosf16_utils.h b/libc/src/math/generic/sincosf16_utils.h index 5e5edd4a8c85b..79fe901b66d41 100644 --- a/libc/src/math/generic/sincosf16_utils.h +++ b/libc/src/math/generic/sincosf16_utils.h @@ -49,24 +49,23 @@ LIBC_INLINE int32_t range_reduction_sincospif16(float x, float &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) +// The precision choice of 'double' in the following function 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(prod - kf); + // Generated by Sollya with: + // > D(32/pi); + constexpr double THIRTYTWO_OVER_PI = 0x1.45f306dc9c883p3; - return static_cast(kf); + double prod = x * THIRTYTWO_OVER_PI; + double kd = fputil::nearest_integer(prod); + y = static_cast(prod - kd); + + return static_cast(kd); } static LIBC_INLINE void sincosf16_poly_eval(int32_t k, float y, float &sin_k, diff --git a/libc/src/math/generic/tanf16.cpp b/libc/src/math/generic/tanf16.cpp new file mode 100644 index 0000000000000..48aa51e456a8a --- /dev/null +++ b/libc/src/math/generic/tanf16.cpp @@ -0,0 +1,115 @@ +//===-- Half-precision tan(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/tanf16.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 = 9; + +constexpr fputil::ExceptValues TANF16_EXCEPTS{{ + // (input, RZ output, RU offset, RD offset, RN offset) + {0x2894, 0x2894, 1, 0, 1}, + {0x3091, 0x3099, 1, 0, 0}, + {0x3098, 0x30a0, 1, 0, 0}, + {0x55ed, 0x3911, 1, 0, 0}, + {0x607b, 0xc638, 0, 1, 1}, + {0x674e, 0x3b7d, 1, 0, 0}, + {0x6807, 0x4014, 1, 0, 1}, + {0x6f4d, 0xbe19, 0, 1, 1}, + {0x7330, 0xcb62, 0, 1, 0}, +}}; + +LLVM_LIBC_FUNCTION(float16, tanf16, (float16 x)) { + using FPBits = fputil::FPBits; + FPBits xbits(x); + + uint16_t x_u = xbits.uintval(); + uint16_t x_abs = x_u & 0x7fff; + bool x_sign = x_u >> 15; + float xf = x; + + // Handle exceptional values + if (auto r = TANF16_EXCEPTS.lookup_odd(x_abs, x_sign); + LIBC_UNLIKELY(r.has_value())) + return r.value(); + + // |x| <= 0x1.d1p-5 + if (LIBC_UNLIKELY(x_abs <= 0x2b44)) { + // |x| <= 0x1.398p-11 + if (LIBC_UNLIKELY(x_abs <= 0x10e6)) { + // tan(+/-0) = +/-0 + if (LIBC_UNLIKELY(x_abs == 0)) + return x; + + int rounding = fputil::quick_get_round(); + + // Exhaustive tests show that, when: + // x > 0, and rounding upward or + // x < 0, and rounding downward then, + // tan(x) = x * 2^-11 + x + 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; + } + + float xsq = xf * xf; + + // Degree-6 minimax odd polynomial of tan(x) generated by Sollya with: + // > P = fpminimax(tan(x)/x, [|0, 2, 4, 6|], [|1, SG...|], [0, pi/32]); + float result = fputil::polyeval(xsq, 0x1p0f, 0x1.555556p-2f, 0x1.110ee4p-3f, + 0x1.be80f6p-5f); + + return fputil::cast(xf * result); + } + + // tan(+/-inf) = NaN, and tan(NaN) = NaN + if (LIBC_UNLIKELY(x_abs >= 0x7c00)) { + // x = +/-inf + if (x_abs == 0x7c00) { + fputil::set_errno_if_required(EDOM); + fputil::raise_except_if_required(FE_INVALID); + } + + return x + FPBits::quiet_nan().get_val(); + } + + // 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 formula: + // tan(x) = sin(x) / cos(x) + // = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k) + float sin_k, cos_k, sin_y, cosm1_y; + sincosf16_eval(xf, sin_k, cos_k, sin_y, cosm1_y); + + // Note that, cosm1_y = cos_y - 1: + using fputil::multiply_add; + return fputil::cast( + multiply_add(sin_y, cos_k, multiply_add(cosm1_y, sin_k, sin_k)) / + multiply_add(sin_y, -sin_k, multiply_add(cosm1_y, cos_k, cos_k))); +} + +} // namespace LIBC_NAMESPACE_DECL diff --git a/libc/src/math/generic/tanpif16.cpp b/libc/src/math/generic/tanpif16.cpp index 67635536ee319..cf4f9917d4537 100644 --- a/libc/src/math/generic/tanpif16.cpp +++ b/libc/src/math/generic/tanpif16.cpp @@ -79,7 +79,7 @@ LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) { // k = round(x * 32) // y = x * 32 - k // - // Once k and y are computed, we then deduce the answer by tthe formula: + // Once k and y are computed, we then deduce the answer by the formula: // tan(x) = sin(x) / cos(x) // = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k) float xf = x; diff --git a/libc/src/math/tanf16.h b/libc/src/math/tanf16.h new file mode 100644 index 0000000000000..bf1b61e9837f7 --- /dev/null +++ b/libc/src/math/tanf16.h @@ -0,0 +1,21 @@ +//===-- Implementation header for tanf16 ------------------------*- 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_TANF16_H +#define LLVM_LIBC_SRC_MATH_TANF16_H + +#include "src/__support/macros/config.h" +#include "src/__support/macros/properties/types.h" + +namespace LIBC_NAMESPACE_DECL { + +float16 tanf16(float16 x); + +} // namespace LIBC_NAMESPACE_DECL + +#endif // LLVM_LIBC_SRC_MATH_TANF16_H diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt index 16e7d4957ba11..ae8518ee4b4cc 100644 --- a/libc/test/src/math/CMakeLists.txt +++ b/libc/test/src/math/CMakeLists.txt @@ -190,6 +190,17 @@ add_fp_unittest( libc.src.__support.FPUtil.fp_bits ) +add_fp_unittest( + tanf16_test + NEED_MPFR + SUITE + libc-math-unittests + SRCS + tanf16_test.cpp + DEPENDS + libc.src.math.tanf16 +) + add_fp_unittest( tanpif16_test NEED_MPFR diff --git a/libc/test/src/math/cosf16_test.cpp b/libc/test/src/math/cosf16_test.cpp index 9e4687f0325c4..b744e7817e4ba 100644 --- a/libc/test/src/math/cosf16_test.cpp +++ b/libc/test/src/math/cosf16_test.cpp @@ -17,7 +17,7 @@ namespace mpfr = LIBC_NAMESPACE::testing::mpfr; // Range: [0, Inf] static constexpr uint16_t POS_START = 0x0000U; -static constexpr uint16_t POS_STOP = 0x7c00u; +static constexpr uint16_t POS_STOP = 0x7c00U; // Range: [-Inf, 0] static constexpr uint16_t NEG_START = 0x8000U; diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt index 31f85a3ecfd27..e23e7f41222d4 100644 --- a/libc/test/src/math/smoke/CMakeLists.txt +++ b/libc/test/src/math/smoke/CMakeLists.txt @@ -121,6 +121,17 @@ add_fp_unittest( libc.src.__support.FPUtil.fp_bits ) +add_fp_unittest( + tanf16_test + SUITE + libc-math-smoke-tests + SRCS + tanf16_test.cpp + DEPENDS + libc.src.errno.errno + libc.src.math.tanf16 +) + add_fp_unittest( tanpif16_test SUITE diff --git a/libc/test/src/math/smoke/tanf16_test.cpp b/libc/test/src/math/smoke/tanf16_test.cpp new file mode 100644 index 0000000000000..39d1182ba891e --- /dev/null +++ b/libc/test/src/math/smoke/tanf16_test.cpp @@ -0,0 +1,34 @@ +//===-- Unittests for tanf16 ----------------------------------------------===// +// +// +// 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/tanf16.h" +#include "test/UnitTest/FPMatcher.h" +#include "test/UnitTest/Test.h" + +using LlvmLibcTanf16Test = LIBC_NAMESPACE::testing::FPTest; + +TEST_F(LlvmLibcTanf16Test, SpecialNumbers) { + LIBC_NAMESPACE::libc_errno = 0; + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::tanf16(aNaN)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ(zero, LIBC_NAMESPACE::tanf16(zero)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ(neg_zero, LIBC_NAMESPACE::tanf16(neg_zero)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::tanf16(inf)); + EXPECT_MATH_ERRNO(EDOM); + + EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::tanf16(neg_inf)); + EXPECT_MATH_ERRNO(EDOM); +} diff --git a/libc/test/src/math/tanf16_test.cpp b/libc/test/src/math/tanf16_test.cpp new file mode 100644 index 0000000000000..f2e874182efc1 --- /dev/null +++ b/libc/test/src/math/tanf16_test.cpp @@ -0,0 +1,40 @@ +//===-- Exhaustive test for tanf16 ----------------------------------------===// +// +// 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/tanf16.h" +#include "test/UnitTest/FPMatcher.h" +#include "test/UnitTest/Test.h" +#include "utils/MPFRWrapper/MPFRUtils.h" + +using LlvmLibcTanf16Test = 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(LlvmLibcTanf16Test, PositiveRange) { + for (uint16_t v = POS_START; v <= POS_STOP; ++v) { + float16 x = FPBits(v).get_val(); + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tan, x, + LIBC_NAMESPACE::tanf16(x), 0.5); + } +} + +TEST_F(LlvmLibcTanf16Test, NegativeRange) { + for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) { + float16 x = FPBits(v).get_val(); + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tan, x, + LIBC_NAMESPACE::tanf16(x), 0.5); + } +}