diff --git a/libc/config/gpu/entrypoints.txt b/libc/config/gpu/entrypoints.txt index 2cc54e8a4b970c..13bb88894297ca 100644 --- a/libc/config/gpu/entrypoints.txt +++ b/libc/config/gpu/entrypoints.txt @@ -567,6 +567,7 @@ if(LIBC_TYPES_HAS_FLOAT16) libc.src.math.llogbf16 libc.src.math.llrintf16 libc.src.math.llroundf16 + libc.src.math.log10f16 libc.src.math.log2f16 libc.src.math.logbf16 libc.src.math.logf16 diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt index 06ea7bba81f345..6ed6ad8c2400f3 100644 --- a/libc/config/linux/x86_64/entrypoints.txt +++ b/libc/config/linux/x86_64/entrypoints.txt @@ -660,6 +660,7 @@ if(LIBC_TYPES_HAS_FLOAT16) libc.src.math.llogbf16 libc.src.math.llrintf16 libc.src.math.llroundf16 + libc.src.math.log10f16 libc.src.math.log2f16 libc.src.math.logbf16 libc.src.math.logf16 diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst index 6591cbbdc15584..88751e2453f2c8 100644 --- a/libc/docs/math/index.rst +++ b/libc/docs/math/index.rst @@ -312,7 +312,7 @@ Higher Math Functions +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ | log | |check| | |check| | | |check| | | 7.12.6.11 | F.10.3.11 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ -| log10 | |check| | |check| | | | | 7.12.6.12 | F.10.3.12 | +| log10 | |check| | |check| | | |check| | | 7.12.6.12 | F.10.3.12 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ | log10p1 | | | | | | 7.12.6.13 | F.10.3.13 | +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+ diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td index d2a073847503ef..33bec2f71627e5 100644 --- a/libc/spec/stdc.td +++ b/libc/spec/stdc.td @@ -642,6 +642,7 @@ def StdC : StandardSpec<"stdc"> { FunctionSpec<"log10", RetValSpec, [ArgSpec]>, FunctionSpec<"log10f", RetValSpec, [ArgSpec]>, + GuardedFunctionSpec<"log10f16", RetValSpec, [ArgSpec], "LIBC_TYPES_HAS_FLOAT16">, FunctionSpec<"log1p", RetValSpec, [ArgSpec]>, FunctionSpec<"log1pf", RetValSpec, [ArgSpec]>, diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt index 516bed499b1941..9239f029abf87a 100644 --- a/libc/src/math/CMakeLists.txt +++ b/libc/src/math/CMakeLists.txt @@ -334,6 +334,7 @@ add_math_entrypoint_object(ldexpf128) add_math_entrypoint_object(log10) add_math_entrypoint_object(log10f) +add_math_entrypoint_object(log10f16) add_math_entrypoint_object(log1p) add_math_entrypoint_object(log1pf) diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt index d7c7a3431d3d95..00cad6f85b4b98 100644 --- a/libc/src/math/generic/CMakeLists.txt +++ b/libc/src/math/generic/CMakeLists.txt @@ -2173,6 +2173,28 @@ add_entrypoint_object( -O3 ) +add_entrypoint_object( + log10f16 + SRCS + log10f16.cpp + HDRS + ../log10f16.h + DEPENDS + .expxf16 + libc.hdr.errno_macros + libc.hdr.fenv_macros + libc.src.__support.FPUtil.cast + libc.src.__support.FPUtil.except_value_utils + 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.macros.optimization + libc.src.__support.macros.properties.cpu_features + COMPILE_OPTIONS + -O3 +) + add_entrypoint_object( log1p SRCS diff --git a/libc/src/math/generic/expxf16.h b/libc/src/math/generic/expxf16.h index 56ed6ee7cc0056..67bb248307519f 100644 --- a/libc/src/math/generic/expxf16.h +++ b/libc/src/math/generic/expxf16.h @@ -316,6 +316,20 @@ constexpr cpp::array LOG2F_F = { 0x1.d053f6p-1f, 0x1.dc899ap-1f, 0x1.e88c6cp-1f, 0x1.f45e08p-1f, }; +// Generated by Sollya with the following commands: +// > display = hexadecimal; +// > for i from 0 to 31 do print(round(log10(1 + i * 2^-5), SG, RN)); +constexpr cpp::array LOG10F_F = { + 0x0p+0f, 0x1.b5e908p-7f, 0x1.af5f92p-6f, 0x1.3ed11ap-5f, + 0x1.a30a9ep-5f, 0x1.02428cp-4f, 0x1.31b306p-4f, 0x1.5fe804p-4f, + 0x1.8cf184p-4f, 0x1.b8de4ep-4f, 0x1.e3bc1ap-4f, 0x1.06cbd6p-3f, + 0x1.1b3e72p-3f, 0x1.2f3b6ap-3f, 0x1.42c7e8p-3f, 0x1.55e8c6p-3f, + 0x1.68a288p-3f, 0x1.7af974p-3f, 0x1.8cf184p-3f, 0x1.9e8e7cp-3f, + 0x1.afd3e4p-3f, 0x1.c0c514p-3f, 0x1.d1653p-3f, 0x1.e1b734p-3f, + 0x1.f1bdeep-3f, 0x1.00be06p-2f, 0x1.087a08p-2f, 0x1.101432p-2f, + 0x1.178da6p-2f, 0x1.1ee778p-2f, 0x1.2622bp-2f, 0x1.2d404cp-2f, +}; + // Generated by Sollya with the following commands: // > display = hexadecimal; // > for i from 0 to 31 do print(round(1 / (1 + i * 2^-5), SG, RN)); diff --git a/libc/src/math/generic/log10f16.cpp b/libc/src/math/generic/log10f16.cpp new file mode 100644 index 00000000000000..990bcabaf68718 --- /dev/null +++ b/libc/src/math/generic/log10f16.cpp @@ -0,0 +1,164 @@ +//===-- Half-precision log10(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/log10f16.h" +#include "expxf16.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/except_value_utils.h" +#include "src/__support/FPUtil/multiply_add.h" +#include "src/__support/common.h" +#include "src/__support/macros/config.h" +#include "src/__support/macros/optimization.h" +#include "src/__support/macros/properties/cpu_features.h" + +namespace LIBC_NAMESPACE_DECL { + +#ifdef LIBC_TARGET_CPU_HAS_FMA +static constexpr size_t N_LOG10F16_EXCEPTS = 11; +#else +static constexpr size_t N_LOG10F16_EXCEPTS = 17; +#endif + +static constexpr fputil::ExceptValues + LOG10F16_EXCEPTS = {{ + // (input, RZ output, RU offset, RD offset, RN offset) + // x = 0x1.e3cp-3, log10f16(x) = -0x1.40cp-1 (RZ) + {0x338fU, 0xb903U, 0U, 1U, 0U}, + // x = 0x1.fep-3, log10f16(x) = -0x1.35p-1 (RZ) + {0x33f8U, 0xb8d4U, 0U, 1U, 1U}, +#ifndef LIBC_TARGET_CPU_HAS_FMA + // x = 0x1.394p-1, log10f16(x) = -0x1.b4cp-3 (RZ) + {0x38e5U, 0xb2d3U, 0U, 1U, 1U}, +#endif + // x = 0x1.ea8p-1, log10f16(x) = -0x1.31p-6 (RZ) + {0x3baaU, 0xa4c4U, 0U, 1U, 1U}, + // x = 0x1.ebp-1, log10f16(x) = -0x1.29cp-6 (RZ) + {0x3bacU, 0xa4a7U, 0U, 1U, 1U}, + // x = 0x1.f3p-1, log10f16(x) = -0x1.6dcp-7 (RZ) + {0x3bccU, 0xa1b7U, 0U, 1U, 1U}, +// x = 0x1.f38p-1, log10f16(x) = -0x1.5f8p-7 (RZ) +#ifndef LIBC_TARGET_CPU_HAS_FMA + {0x3bceU, 0xa17eU, 0U, 1U, 1U}, + // x = 0x1.fd8p-1, log10f16(x) = -0x1.168p-9 (RZ) + {0x3bf6U, 0x985aU, 0U, 1U, 1U}, + // x = 0x1.ff8p-1, log10f16(x) = -0x1.bccp-12 (RZ) + {0x3bfeU, 0x8ef3U, 0U, 1U, 1U}, + // x = 0x1.374p+0, log10f16(x) = 0x1.5b8p-4 (RZ) + {0x3cddU, 0x2d6eU, 1U, 0U, 1U}, + // x = 0x1.3ecp+1, log10f16(x) = 0x1.958p-2 (RZ) + {0x40fbU, 0x3656U, 1U, 0U, 1U}, +#endif + // x = 0x1.4p+3, log10f16(x) = 0x1p+0 (RZ) + {0x4900U, 0x3c00U, 0U, 0U, 0U}, + // x = 0x1.9p+6, log10f16(x) = 0x1p+1 (RZ) + {0x5640U, 0x4000U, 0U, 0U, 0U}, + // x = 0x1.f84p+6, log10f16(x) = 0x1.0ccp+1 (RZ) + {0x57e1U, 0x4033U, 1U, 0U, 0U}, + // x = 0x1.f4p+9, log10f16(x) = 0x1.8p+1 (RZ) + {0x63d0U, 0x4200U, 0U, 0U, 0U}, + // x = 0x1.388p+13, log10f16(x) = 0x1p+2 (RZ) + {0x70e2U, 0x4400U, 0U, 0U, 0U}, + // x = 0x1.674p+13, log10f16(x) = 0x1.03cp+2 (RZ) + {0x719dU, 0x440fU, 1U, 0U, 0U}, + }}; + +LLVM_LIBC_FUNCTION(float16, log10f16, (float16 x)) { + using FPBits = fputil::FPBits; + FPBits x_bits(x); + + uint16_t x_u = x_bits.uintval(); + + // If x <= 0, or x is 1, or x is +inf, or x is NaN. + if (LIBC_UNLIKELY(x_u == 0U || x_u == 0x3c00U || x_u >= 0x7c00U)) { + // log10(NaN) = NaN + if (x_bits.is_nan()) { + if (x_bits.is_signaling_nan()) { + fputil::raise_except_if_required(FE_INVALID); + return FPBits::quiet_nan().get_val(); + } + + return x; + } + + // log10(+/-0) = −inf + if ((x_u & 0x7fffU) == 0U) { + fputil::raise_except_if_required(FE_DIVBYZERO); + return FPBits::inf(Sign::NEG).get_val(); + } + + if (x_u == 0x3c00U) + return FPBits::zero().get_val(); + + // When x < 0. + if (x_u > 0x8000U) { + fputil::set_errno_if_required(EDOM); + fputil::raise_except_if_required(FE_INVALID); + return FPBits::quiet_nan().get_val(); + } + + // log10(+inf) = +inf + return FPBits::inf().get_val(); + } + + if (auto r = LOG10F16_EXCEPTS.lookup(x_u); LIBC_UNLIKELY(r.has_value())) + return r.value(); + + // To compute log10(x), we perform the following range reduction: + // x = 2^m * 1.mant, + // log10(x) = m * log10(2) + log10(1.mant). + // To compute log10(1.mant), let f be the highest 6 bits including the hidden + // bit, and d be the difference (1.mant - f), i.e., the remaining 5 bits of + // the mantissa, then: + // log10(1.mant) = log10(f) + log10(1.mant / f) + // = log10(f) + log10(1 + d/f) + // since d/f is sufficiently small. + // We store log10(f) and 1/f in the lookup tables LOG10F_F and ONE_OVER_F_F + // respectively. + + int m = -FPBits::EXP_BIAS; + + // When x is subnormal, normalize it. + if ((x_u & FPBits::EXP_MASK) == 0U) { + // Can't pass an integer to fputil::cast directly. + constexpr float NORMALIZE_EXP = 1U << FPBits::FRACTION_LEN; + x_bits = FPBits(x_bits.get_val() * fputil::cast(NORMALIZE_EXP)); + x_u = x_bits.uintval(); + m -= FPBits::FRACTION_LEN; + } + + uint16_t mant = x_bits.get_mantissa(); + // Leading 10 - 5 = 5 bits of the mantissa. + int f = mant >> 5; + // Unbiased exponent. + m += x_u >> FPBits::FRACTION_LEN; + + // Set bits to 1.mant instead of 2^m * 1.mant. + x_bits.set_biased_exponent(FPBits::EXP_BIAS); + float mant_f = x_bits.get_val(); + // v = 1.mant * 1/f - 1 = d/f + float v = fputil::multiply_add(mant_f, ONE_OVER_F_F[f], -1.0f); + + // Degree-3 minimax polynomial generated by Sollya with the following + // commands: + // > display = hexadecimal; + // > P = fpminimax(log10(1 + x)/x, 2, [|SG...|], [-2^-5, 2^-5]); + // > x * P; + float log10p1_d_over_f = + v * fputil::polyeval(v, 0x1.bcb7bp-2f, -0x1.bce168p-3f, 0x1.28acb8p-3f); + // log10(1.mant) = log10(f) + log10(1 + d/f) + float log10_1_mant = LOG10F_F[f] + log10p1_d_over_f; + return fputil::cast( + fputil::multiply_add(static_cast(m), LOG10F_2, log10_1_mant)); +} + +} // namespace LIBC_NAMESPACE_DECL diff --git a/libc/src/math/log10f16.h b/libc/src/math/log10f16.h new file mode 100644 index 00000000000000..298deb370e0b0f --- /dev/null +++ b/libc/src/math/log10f16.h @@ -0,0 +1,21 @@ +//===-- Implementation header for log10f16 ----------------------*- 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_LOG10F16_H +#define LLVM_LIBC_SRC_MATH_LOG10F16_H + +#include "src/__support/macros/config.h" +#include "src/__support/macros/properties/types.h" + +namespace LIBC_NAMESPACE_DECL { + +float16 log10f16(float16 x); + +} // namespace LIBC_NAMESPACE_DECL + +#endif // LLVM_LIBC_SRC_MATH_LOG10F16_H diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt index 24a5abec898a89..befa8cff0720cf 100644 --- a/libc/test/src/math/CMakeLists.txt +++ b/libc/test/src/math/CMakeLists.txt @@ -1846,6 +1846,17 @@ add_fp_unittest( libc.src.__support.FPUtil.fp_bits ) +add_fp_unittest( + log10f16_test + NEED_MPFR + SUITE + libc-math-unittests + SRCS + log10f16_test.cpp + DEPENDS + libc.src.math.log10f16 +) + add_fp_unittest( log1p_test NEED_MPFR diff --git a/libc/test/src/math/log10f16_test.cpp b/libc/test/src/math/log10f16_test.cpp new file mode 100644 index 00000000000000..a71e3309ac5f08 --- /dev/null +++ b/libc/test/src/math/log10f16_test.cpp @@ -0,0 +1,40 @@ +//===-- Exhaustive test for log10f16 --------------------------------------===// +// +// 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/log10f16.h" +#include "test/UnitTest/FPMatcher.h" +#include "test/UnitTest/Test.h" +#include "utils/MPFRWrapper/MPFRUtils.h" + +using LlvmLibcLog10f16Test = 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(LlvmLibcLog10f16Test, PositiveRange) { + for (uint16_t v = POS_START; v <= POS_STOP; ++v) { + float16 x = FPBits(v).get_val(); + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log10, x, + LIBC_NAMESPACE::log10f16(x), 0.5); + } +} + +TEST_F(LlvmLibcLog10f16Test, NegativeRange) { + for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) { + float16 x = FPBits(v).get_val(); + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log10, x, + LIBC_NAMESPACE::log10f16(x), 0.5); + } +} diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt index 3c077240356bd3..d41041c9bb0a4a 100644 --- a/libc/test/src/math/smoke/CMakeLists.txt +++ b/libc/test/src/math/smoke/CMakeLists.txt @@ -3632,6 +3632,19 @@ add_fp_unittest( libc.src.__support.FPUtil.fp_bits ) +add_fp_unittest( + log10f16_test + SUITE + libc-math-smoke-tests + SRCS + log10f16_test.cpp + DEPENDS + libc.hdr.fenv_macros + libc.src.errno.errno + libc.src.math.log10f16 + libc.src.__support.FPUtil.cast +) + add_fp_unittest( log1p_test SUITE diff --git a/libc/test/src/math/smoke/log10f16_test.cpp b/libc/test/src/math/smoke/log10f16_test.cpp new file mode 100644 index 00000000000000..471e1989333268 --- /dev/null +++ b/libc/test/src/math/smoke/log10f16_test.cpp @@ -0,0 +1,50 @@ +//===-- Unittests for log10f16 --------------------------------------------===// +// +// 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 "hdr/fenv_macros.h" +#include "src/__support/FPUtil/cast.h" +#include "src/errno/libc_errno.h" +#include "src/math/log10f16.h" +#include "test/UnitTest/FPMatcher.h" +#include "test/UnitTest/Test.h" + +using LlvmLibcLog10f16Test = LIBC_NAMESPACE::testing::FPTest; + +TEST_F(LlvmLibcLog10f16Test, SpecialNumbers) { + LIBC_NAMESPACE::libc_errno = 0; + + EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::log10f16(aNaN)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::log10f16(sNaN), FE_INVALID); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_ALL_ROUNDING(inf, LIBC_NAMESPACE::log10f16(inf)); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::log10f16(neg_inf)); + EXPECT_MATH_ERRNO(EDOM); + + EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING( + neg_inf, LIBC_NAMESPACE::log10f16(zero), FE_DIVBYZERO); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING( + neg_inf, LIBC_NAMESPACE::log10f16(neg_zero), FE_DIVBYZERO); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_ALL_ROUNDING( + zero, + LIBC_NAMESPACE::log10f16(LIBC_NAMESPACE::fputil::cast(1.0))); + EXPECT_MATH_ERRNO(0); + + EXPECT_FP_EQ_ALL_ROUNDING( + aNaN, + LIBC_NAMESPACE::log10f16(LIBC_NAMESPACE::fputil::cast(-1.0))); + EXPECT_MATH_ERRNO(EDOM); +}