diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt --- a/libc/config/linux/aarch64/entrypoints.txt +++ b/libc/config/linux/aarch64/entrypoints.txt @@ -145,6 +145,7 @@ libc.src.math.ldexp libc.src.math.ldexpf libc.src.math.ldexpl + libc.src.math.log2f libc.src.math.logf libc.src.math.logb libc.src.math.logbf diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt --- a/libc/config/linux/x86_64/entrypoints.txt +++ b/libc/config/linux/x86_64/entrypoints.txt @@ -144,6 +144,7 @@ libc.src.math.llround libc.src.math.llroundf libc.src.math.llroundl + libc.src.math.log2f libc.src.math.logf libc.src.math.logb libc.src.math.logbf diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt --- a/libc/config/windows/entrypoints.txt +++ b/libc/config/windows/entrypoints.txt @@ -118,6 +118,7 @@ libc.src.math.llround libc.src.math.llroundf libc.src.math.llroundl + libc.src.math.log2f libc.src.math.logf libc.src.math.logb libc.src.math.logbf diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td --- a/libc/spec/stdc.td +++ b/libc/spec/stdc.td @@ -396,6 +396,8 @@ FunctionSpec<"ldexpf", RetValSpec, [ArgSpec, ArgSpec]>, FunctionSpec<"ldexpl", RetValSpec, [ArgSpec, ArgSpec]>, + FunctionSpec<"log2f", RetValSpec, [ArgSpec]>, + FunctionSpec<"logf", RetValSpec, [ArgSpec]>, FunctionSpec<"logb", RetValSpec, [ArgSpec]>, diff --git a/libc/src/__support/FPUtil/PolyEval.h b/libc/src/__support/FPUtil/PolyEval.h --- a/libc/src/__support/FPUtil/PolyEval.h +++ b/libc/src/__support/FPUtil/PolyEval.h @@ -37,7 +37,9 @@ #ifdef LLVM_LIBC_ARCH_X86_64 -#include "x86_64/PolyEval.h" +// [DISABLED] There is a regression with using vectorized version for polyeval +// compared to the naive Horner's scheme with fma. Need further investigation +// #include "x86_64/PolyEval.h" #endif // LLVM_LIBC_ARCH_X86_64 diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt --- a/libc/src/math/CMakeLists.txt +++ b/libc/src/math/CMakeLists.txt @@ -116,6 +116,8 @@ add_math_entrypoint_object(ldexpf) add_math_entrypoint_object(ldexpl) +add_math_entrypoint_object(log2f) + add_math_entrypoint_object(logf) add_math_entrypoint_object(logb) diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt --- a/libc/src/math/generic/CMakeLists.txt +++ b/libc/src/math/generic/CMakeLists.txt @@ -645,6 +645,30 @@ -O2 ) +add_object_library( + common_constants + HDRS + common_constants.h + SRCS + common_constants.cpp + COMPILE_OPTIONS + -Wno-c++17-extensions +) + +add_entrypoint_object( + log2f + SRCS + log2f.cpp + HDRS + ../log2f.h + DEPENDS + .common_constants + libc.src.__support.FPUtil.fputil + COMPILE_OPTIONS + -O3 + -Wno-c++17-extensions +) + add_entrypoint_object( logf SRCS @@ -652,6 +676,7 @@ HDRS ../logf.h DEPENDS + .common_constants libc.src.__support.FPUtil.fputil COMPILE_OPTIONS -O3 diff --git a/libc/src/math/generic/common_constants.h b/libc/src/math/generic/common_constants.h new file mode 100644 --- /dev/null +++ b/libc/src/math/generic/common_constants.h @@ -0,0 +1,19 @@ +//===-- Common constants for math functions ---------------------*- 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_GENERIC_COMMON_CONSTANTS_H +#define LLVM_LIBC_SRC_MATH_GENERIC_COMMON_CONSTANTS_H + +namespace __llvm_libc { + +// Lookup table for (1/f) where f = 1 + n*2^(-7), n = 0..127. +extern const double ONE_OVER_F[128]; + +} // namespace __llvm_libc + +#endif // LLVM_LIBC_SRC_MATH_GENERIC_COMMON_CONSTANTS_H diff --git a/libc/src/math/generic/common_constants.cpp b/libc/src/math/generic/common_constants.cpp new file mode 100644 --- /dev/null +++ b/libc/src/math/generic/common_constants.cpp @@ -0,0 +1,59 @@ +//===-- Common constants for math functions ---------------------*- 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 +// +//===----------------------------------------------------------------------===// + +#include "common_constants.h" + +namespace __llvm_libc { + +// Lookup table for (1/f) where f = 1 + n*2^(-7), n = 0..127. +const double ONE_OVER_F[128] = { + 0x1.0000000000000p+0, 0x1.fc07f01fc07f0p-1, 0x1.f81f81f81f820p-1, + 0x1.f44659e4a4271p-1, 0x1.f07c1f07c1f08p-1, 0x1.ecc07b301ecc0p-1, + 0x1.e9131abf0b767p-1, 0x1.e573ac901e574p-1, 0x1.e1e1e1e1e1e1ep-1, + 0x1.de5d6e3f8868ap-1, 0x1.dae6076b981dbp-1, 0x1.d77b654b82c34p-1, + 0x1.d41d41d41d41dp-1, 0x1.d0cb58f6ec074p-1, 0x1.cd85689039b0bp-1, + 0x1.ca4b3055ee191p-1, 0x1.c71c71c71c71cp-1, 0x1.c3f8f01c3f8f0p-1, + 0x1.c0e070381c0e0p-1, 0x1.bdd2b899406f7p-1, 0x1.bacf914c1bad0p-1, + 0x1.b7d6c3dda338bp-1, 0x1.b4e81b4e81b4fp-1, 0x1.b2036406c80d9p-1, + 0x1.af286bca1af28p-1, 0x1.ac5701ac5701bp-1, 0x1.a98ef606a63bep-1, + 0x1.a6d01a6d01a6dp-1, 0x1.a41a41a41a41ap-1, 0x1.a16d3f97a4b02p-1, + 0x1.9ec8e951033d9p-1, 0x1.9c2d14ee4a102p-1, 0x1.999999999999ap-1, + 0x1.970e4f80cb872p-1, 0x1.948b0fcd6e9e0p-1, 0x1.920fb49d0e229p-1, + 0x1.8f9c18f9c18fap-1, 0x1.8d3018d3018d3p-1, 0x1.8acb90f6bf3aap-1, + 0x1.886e5f0abb04ap-1, 0x1.8618618618618p-1, 0x1.83c977ab2beddp-1, + 0x1.8181818181818p-1, 0x1.7f405fd017f40p-1, 0x1.7d05f417d05f4p-1, + 0x1.7ad2208e0ecc3p-1, 0x1.78a4c8178a4c8p-1, 0x1.767dce434a9b1p-1, + 0x1.745d1745d1746p-1, 0x1.724287f46debcp-1, 0x1.702e05c0b8170p-1, + 0x1.6e1f76b4337c7p-1, 0x1.6c16c16c16c17p-1, 0x1.6a13cd1537290p-1, + 0x1.6816816816817p-1, 0x1.661ec6a5122f9p-1, 0x1.642c8590b2164p-1, + 0x1.623fa77016240p-1, 0x1.6058160581606p-1, 0x1.5e75bb8d015e7p-1, + 0x1.5c9882b931057p-1, 0x1.5ac056b015ac0p-1, 0x1.58ed2308158edp-1, + 0x1.571ed3c506b3ap-1, 0x1.5555555555555p-1, 0x1.5390948f40febp-1, + 0x1.51d07eae2f815p-1, 0x1.5015015015015p-1, 0x1.4e5e0a72f0539p-1, + 0x1.4cab88725af6ep-1, 0x1.4afd6a052bf5bp-1, 0x1.49539e3b2d067p-1, + 0x1.47ae147ae147bp-1, 0x1.460cbc7f5cf9ap-1, 0x1.446f86562d9fbp-1, + 0x1.42d6625d51f87p-1, 0x1.4141414141414p-1, 0x1.3fb013fb013fbp-1, + 0x1.3e22cbce4a902p-1, 0x1.3c995a47babe7p-1, 0x1.3b13b13b13b14p-1, + 0x1.3991c2c187f63p-1, 0x1.3813813813814p-1, 0x1.3698df3de0748p-1, + 0x1.3521cfb2b78c1p-1, 0x1.33ae45b57bcb2p-1, 0x1.323e34a2b10bfp-1, + 0x1.30d190130d190p-1, 0x1.2f684bda12f68p-1, 0x1.2e025c04b8097p-1, + 0x1.2c9fb4d812ca0p-1, 0x1.2b404ad012b40p-1, 0x1.29e4129e4129ep-1, + 0x1.288b01288b013p-1, 0x1.27350b8812735p-1, 0x1.25e22708092f1p-1, + 0x1.2492492492492p-1, 0x1.23456789abcdfp-1, 0x1.21fb78121fb78p-1, + 0x1.20b470c67c0d9p-1, 0x1.1f7047dc11f70p-1, 0x1.1e2ef3b3fb874p-1, + 0x1.1cf06ada2811dp-1, 0x1.1bb4a4046ed29p-1, 0x1.1a7b9611a7b96p-1, + 0x1.19453808ca29cp-1, 0x1.1811811811812p-1, 0x1.16e0689427379p-1, + 0x1.15b1e5f75270dp-1, 0x1.1485f0e0acd3bp-1, 0x1.135c81135c811p-1, + 0x1.12358e75d3033p-1, 0x1.1111111111111p-1, 0x1.0fef010fef011p-1, + 0x1.0ecf56be69c90p-1, 0x1.0db20a88f4696p-1, 0x1.0c9714fbcda3bp-1, + 0x1.0b7e6ec259dc8p-1, 0x1.0a6810a6810a7p-1, 0x1.0953f39010954p-1, + 0x1.0842108421084p-1, 0x1.073260a47f7c6p-1, 0x1.0624dd2f1a9fcp-1, + 0x1.05197f7d73404p-1, 0x1.0410410410410p-1, 0x1.03091b51f5e1ap-1, + 0x1.0204081020408p-1, 0x1.0101010101010p-1}; + +} // namespace __llvm_libc diff --git a/libc/src/math/generic/log2f.cpp b/libc/src/math/generic/log2f.cpp new file mode 100644 --- /dev/null +++ b/libc/src/math/generic/log2f.cpp @@ -0,0 +1,150 @@ +//===-- Single-precision log2(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/log2f.h" +#include "common_constants.h" // Lookup table for (1/f) +#include "src/__support/FPUtil/BasicOperations.h" +#include "src/__support/FPUtil/FEnvUtils.h" +#include "src/__support/FPUtil/FMA.h" +#include "src/__support/FPUtil/FPBits.h" +#include "src/__support/FPUtil/PolyEval.h" +#include "src/__support/common.h" + +// This is a correctly-rounded algorithm for log2(x) in single precision with +// round-to-nearest, tie-to-even mode from the RLIBM project at: +// https://people.cs.rutgers.edu/~sn349/rlibm + +// Step 1 - Range reduction: +// For x = 2^m * 1.mant, log2(x) = m + log2(1.m) +// If x is denormal, we normalize it by multiplying x by 2^23 and subtracting +// m by 23. + +// Step 2 - Another range reduction: +// To compute log(1.mant), let f be the highest 8 bits including the hidden +// bit, and d be the difference (1.mant - f), i.e. the remaining 16 bits of the +// mantissa. Then we have the following approximation formula: +// log2(1.mant) = log2(f) + log2(1.mant / f) +// = log2(f) + log2(1 + d/f) +// ~ log2(f) + P(d/f) +// since d/f is sufficiently small. +// log2(f) and 1/f are then stored in two 2^7 = 128 entries look-up tables. + +// Step 3 - Polynomial approximation: +// To compute P(d/f), we use a single degree-5 polynomial in double precision +// which provides correct rounding for all but few exception values. +// For more detail about how this polynomial is obtained, please refer to the +// paper: +// Lim, J. and Nagarakatte, S., "One Polynomial Approximation to Produce +// Correctly Rounded Results of an Elementary Function for Multiple +// Representations and Rounding Modes", Proceedings of the 49th ACM SIGPLAN +// Symposium on Principles of Programming Languages (POPL-2022), Philadelphia, +// USA, January 16-22, 2022. +// https://people.cs.rutgers.edu/~sn349/papers/rlibmall-popl-2022.pdf + +namespace __llvm_libc { + +// Lookup table for log2(f) = log2(1 + n*2^(-7)) where n = 0..127. +static constexpr double LOG2_F[128] = { + 0x0.0000000000000p+0, 0x1.6fe50b6ef0851p-7, 0x1.6e79685c2d22ap-6, + 0x1.11cd1d5133413p-5, 0x1.6bad3758efd87p-5, 0x1.c4dfab90aab5fp-5, + 0x1.0eb389fa29f9bp-4, 0x1.3aa2fdd27f1c3p-4, 0x1.663f6fac91316p-4, + 0x1.918a16e46335bp-4, 0x1.bc84240adabbap-4, 0x1.e72ec117fa5b2p-4, + 0x1.08c588cda79e4p-3, 0x1.1dcd197552b7bp-3, 0x1.32ae9e278ae1ap-3, + 0x1.476a9f983f74dp-3, 0x1.5c01a39fbd688p-3, 0x1.70742d4ef027fp-3, + 0x1.84c2bd02f03b3p-3, 0x1.98edd077e70dfp-3, 0x1.acf5e2db4ec94p-3, + 0x1.c0db6cdd94deep-3, 0x1.d49ee4c325970p-3, 0x1.e840be74e6a4dp-3, + 0x1.fbc16b902680ap-3, 0x1.0790adbb03009p-2, 0x1.11307dad30b76p-2, + 0x1.1ac05b291f070p-2, 0x1.24407ab0e073ap-2, 0x1.2db10fc4d9aafp-2, + 0x1.37124cea4cdedp-2, 0x1.406463b1b0449p-2, 0x1.49a784bcd1b8bp-2, + 0x1.52dbdfc4c96b3p-2, 0x1.5c01a39fbd688p-2, 0x1.6518fe4677ba7p-2, + 0x1.6e221cd9d0cdep-2, 0x1.771d2ba7efb3cp-2, 0x1.800a563161c54p-2, + 0x1.88e9c72e0b226p-2, 0x1.91bba891f1709p-2, 0x1.9a802391e232fp-2, + 0x1.a33760a7f6051p-2, 0x1.abe18797f1f49p-2, 0x1.b47ebf73882a1p-2, + 0x1.bd0f2e9e79031p-2, 0x1.c592fad295b56p-2, 0x1.ce0a4923a587dp-2, + 0x1.d6753e032ea0fp-2, 0x1.ded3fd442364cp-2, 0x1.e726aa1e754d2p-2, + 0x1.ef6d67328e220p-2, 0x1.f7a8568cb06cfp-2, 0x1.ffd799a83ff9bp-2, + 0x1.03fda8b97997fp-1, 0x1.0809cf27f703dp-1, 0x1.0c10500d63aa6p-1, + 0x1.10113b153c8eap-1, 0x1.140c9faa1e544p-1, 0x1.18028cf72976ap-1, + 0x1.1bf311e95d00ep-1, 0x1.1fde3d30e8126p-1, 0x1.23c41d42727c8p-1, + 0x1.27a4c0585cbf8p-1, 0x1.2b803473f7ad1p-1, 0x1.2f56875eb3f26p-1, + 0x1.3327c6ab49ca7p-1, 0x1.36f3ffb6d9162p-1, 0x1.3abb3faa02167p-1, + 0x1.3e7d9379f7016p-1, 0x1.423b07e986aa9p-1, 0x1.45f3a98a20739p-1, + 0x1.49a784bcd1b8bp-1, 0x1.4d56a5b33cec4p-1, 0x1.510118708a8f9p-1, + 0x1.54a6e8ca5438ep-1, 0x1.5848226989d34p-1, 0x1.5be4d0cb51435p-1, + 0x1.5f7cff41e09afp-1, 0x1.6310b8f553048p-1, 0x1.66a008e4788ccp-1, + 0x1.6a2af9e5a0f0ap-1, 0x1.6db196a76194ap-1, 0x1.7133e9b156c7cp-1, + 0x1.74b1fd64e0754p-1, 0x1.782bdbfdda657p-1, 0x1.7ba18f93502e4p-1, + 0x1.7f1322182cf16p-1, 0x1.82809d5be7073p-1, 0x1.85ea0b0b27b26p-1, + 0x1.894f74b06ef8bp-1, 0x1.8cb0e3b4b3bbep-1, 0x1.900e6160002cdp-1, + 0x1.9367f6da0ab2fp-1, 0x1.96bdad2acb5f6p-1, 0x1.9a0f8d3b0e050p-1, + 0x1.9d5d9fd5010b3p-1, 0x1.a0a7eda4c112dp-1, 0x1.a3ee7f38e181fp-1, + 0x1.a7315d02f20c8p-1, 0x1.aa708f58014d3p-1, 0x1.adac1e711c833p-1, + 0x1.b0e4126bcc86cp-1, 0x1.b418734a9008cp-1, 0x1.b74948f5532dap-1, + 0x1.ba769b39e4964p-1, 0x1.bda071cc67e6ep-1, 0x1.c0c6d447c5dd3p-1, + 0x1.c3e9ca2e1a055p-1, 0x1.c7095ae91e1c7p-1, 0x1.ca258dca93316p-1, + 0x1.cd3e6a0ca8907p-1, 0x1.d053f6d260896p-1, 0x1.d3663b27f31d5p-1, + 0x1.d6753e032ea0fp-1, 0x1.d9810643d6615p-1, 0x1.dc899ab3ff56cp-1, + 0x1.df8f02086af2cp-1, 0x1.e29142e0e0140p-1, 0x1.e59063c8822cep-1, + 0x1.e88c6b3626a73p-1, 0x1.eb855f8ca88fbp-1, 0x1.ee7b471b3a950p-1, + 0x1.f16e281db7630p-1, 0x1.f45e08bcf0655p-1, 0x1.f74aef0efafaep-1, + 0x1.fa34e1177c233p-1, 0x1.fd1be4c7f2af9p-1}; + +INLINE_FMA +LLVM_LIBC_FUNCTION(float, log2f, (float x)) { + using FPBits = typename fputil::FPBits; + FPBits xbits(x); + int m = 0; + + // Hard to round value(s). + if (FPBits(x).uintval() == 0x3f81d0b5U) { + int rounding_mode = fputil::get_round(); + if (rounding_mode == FE_DOWNWARD || rounding_mode == FE_TOWARDZERO) { + return 0x1.4cdc4cp-6f; + } + } + + // Exceptional inputs. + if (xbits.uintval() < FPBits::MIN_NORMAL || + xbits.uintval() > FPBits::MAX_NORMAL) { + if (xbits.is_zero()) { + return static_cast(FPBits::neg_inf()); + } + if (xbits.get_sign() && !xbits.is_nan()) { + return FPBits::build_nan(1 << (fputil::MantissaWidth::VALUE - 1)); + } + if (xbits.is_inf_or_nan()) { + return x; + } + // Normalize denormal inputs. + xbits.val *= 0x1.0p23f; + m = -23; + } + + m += xbits.get_exponent(); + // Set bits to 1.m + xbits.set_unbiased_exponent(0x7F); + // Get the 8 highest bits, use 7 bits (excluding the implicit hidden bit) for + // lookup tables. + int fIndex = xbits.get_mantissa() >> 16; + + FPBits f(xbits.val); + // Clear the lowest 16 bits. + f.bits &= ~0x0000'FFFF; + + double d = static_cast(xbits) - static_cast(f); + d *= ONE_OVER_F[fIndex]; + + double extra_factor = static_cast(m) + LOG2_F[fIndex]; + double r = __llvm_libc::fputil::polyeval( + d, extra_factor, 0x1.71547652bd4fp+0, -0x1.7154769b978c7p-1, + 0x1.ec71a99e349c8p-2, -0x1.720d90e6aac6cp-2, 0x1.5132da3583dap-2); + + return static_cast(r); +} + +} // namespace __llvm_libc diff --git a/libc/src/math/generic/logf.cpp b/libc/src/math/generic/logf.cpp --- a/libc/src/math/generic/logf.cpp +++ b/libc/src/math/generic/logf.cpp @@ -7,6 +7,7 @@ //===----------------------------------------------------------------------===// #include "src/math/logf.h" +#include "common_constants.h" // Lookup table for (1/f) #include "src/__support/FPUtil/BasicOperations.h" #include "src/__support/FPUtil/FMA.h" #include "src/__support/FPUtil/FPBits.h" @@ -95,52 +96,6 @@ 0x1.58cadb5cd7989p-1, 0x1.5ad404c359f2cp-1, 0x1.5cdb1dc6c1764p-1, 0x1.5ee02a9241675p-1, 0x1.60e32f44788d8p-1}; -// Lookup table for (1/f) where f = 1 + n*2^(-7), n = 0..127. -static constexpr double ONE_OVER_F[128] = { - 0x1.0000000000000p+0, 0x1.fc07f01fc07f0p-1, 0x1.f81f81f81f820p-1, - 0x1.f44659e4a4271p-1, 0x1.f07c1f07c1f08p-1, 0x1.ecc07b301ecc0p-1, - 0x1.e9131abf0b767p-1, 0x1.e573ac901e574p-1, 0x1.e1e1e1e1e1e1ep-1, - 0x1.de5d6e3f8868ap-1, 0x1.dae6076b981dbp-1, 0x1.d77b654b82c34p-1, - 0x1.d41d41d41d41dp-1, 0x1.d0cb58f6ec074p-1, 0x1.cd85689039b0bp-1, - 0x1.ca4b3055ee191p-1, 0x1.c71c71c71c71cp-1, 0x1.c3f8f01c3f8f0p-1, - 0x1.c0e070381c0e0p-1, 0x1.bdd2b899406f7p-1, 0x1.bacf914c1bad0p-1, - 0x1.b7d6c3dda338bp-1, 0x1.b4e81b4e81b4fp-1, 0x1.b2036406c80d9p-1, - 0x1.af286bca1af28p-1, 0x1.ac5701ac5701bp-1, 0x1.a98ef606a63bep-1, - 0x1.a6d01a6d01a6dp-1, 0x1.a41a41a41a41ap-1, 0x1.a16d3f97a4b02p-1, - 0x1.9ec8e951033d9p-1, 0x1.9c2d14ee4a102p-1, 0x1.999999999999ap-1, - 0x1.970e4f80cb872p-1, 0x1.948b0fcd6e9e0p-1, 0x1.920fb49d0e229p-1, - 0x1.8f9c18f9c18fap-1, 0x1.8d3018d3018d3p-1, 0x1.8acb90f6bf3aap-1, - 0x1.886e5f0abb04ap-1, 0x1.8618618618618p-1, 0x1.83c977ab2beddp-1, - 0x1.8181818181818p-1, 0x1.7f405fd017f40p-1, 0x1.7d05f417d05f4p-1, - 0x1.7ad2208e0ecc3p-1, 0x1.78a4c8178a4c8p-1, 0x1.767dce434a9b1p-1, - 0x1.745d1745d1746p-1, 0x1.724287f46debcp-1, 0x1.702e05c0b8170p-1, - 0x1.6e1f76b4337c7p-1, 0x1.6c16c16c16c17p-1, 0x1.6a13cd1537290p-1, - 0x1.6816816816817p-1, 0x1.661ec6a5122f9p-1, 0x1.642c8590b2164p-1, - 0x1.623fa77016240p-1, 0x1.6058160581606p-1, 0x1.5e75bb8d015e7p-1, - 0x1.5c9882b931057p-1, 0x1.5ac056b015ac0p-1, 0x1.58ed2308158edp-1, - 0x1.571ed3c506b3ap-1, 0x1.5555555555555p-1, 0x1.5390948f40febp-1, - 0x1.51d07eae2f815p-1, 0x1.5015015015015p-1, 0x1.4e5e0a72f0539p-1, - 0x1.4cab88725af6ep-1, 0x1.4afd6a052bf5bp-1, 0x1.49539e3b2d067p-1, - 0x1.47ae147ae147bp-1, 0x1.460cbc7f5cf9ap-1, 0x1.446f86562d9fbp-1, - 0x1.42d6625d51f87p-1, 0x1.4141414141414p-1, 0x1.3fb013fb013fbp-1, - 0x1.3e22cbce4a902p-1, 0x1.3c995a47babe7p-1, 0x1.3b13b13b13b14p-1, - 0x1.3991c2c187f63p-1, 0x1.3813813813814p-1, 0x1.3698df3de0748p-1, - 0x1.3521cfb2b78c1p-1, 0x1.33ae45b57bcb2p-1, 0x1.323e34a2b10bfp-1, - 0x1.30d190130d190p-1, 0x1.2f684bda12f68p-1, 0x1.2e025c04b8097p-1, - 0x1.2c9fb4d812ca0p-1, 0x1.2b404ad012b40p-1, 0x1.29e4129e4129ep-1, - 0x1.288b01288b013p-1, 0x1.27350b8812735p-1, 0x1.25e22708092f1p-1, - 0x1.2492492492492p-1, 0x1.23456789abcdfp-1, 0x1.21fb78121fb78p-1, - 0x1.20b470c67c0d9p-1, 0x1.1f7047dc11f70p-1, 0x1.1e2ef3b3fb874p-1, - 0x1.1cf06ada2811dp-1, 0x1.1bb4a4046ed29p-1, 0x1.1a7b9611a7b96p-1, - 0x1.19453808ca29cp-1, 0x1.1811811811812p-1, 0x1.16e0689427379p-1, - 0x1.15b1e5f75270dp-1, 0x1.1485f0e0acd3bp-1, 0x1.135c81135c811p-1, - 0x1.12358e75d3033p-1, 0x1.1111111111111p-1, 0x1.0fef010fef011p-1, - 0x1.0ecf56be69c90p-1, 0x1.0db20a88f4696p-1, 0x1.0c9714fbcda3bp-1, - 0x1.0b7e6ec259dc8p-1, 0x1.0a6810a6810a7p-1, 0x1.0953f39010954p-1, - 0x1.0842108421084p-1, 0x1.073260a47f7c6p-1, 0x1.0624dd2f1a9fcp-1, - 0x1.05197f7d73404p-1, 0x1.0410410410410p-1, 0x1.03091b51f5e1ap-1, - 0x1.0204081020408p-1, 0x1.0101010101010p-1}; - INLINE_FMA LLVM_LIBC_FUNCTION(float, logf, (float x)) { constexpr double LOG_2 = 0x1.62e42fefa39efp-1; diff --git a/libc/src/math/log2f.h b/libc/src/math/log2f.h new file mode 100644 --- /dev/null +++ b/libc/src/math/log2f.h @@ -0,0 +1,18 @@ +//===-- Implementation header for log2f -------------------------*- 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_LOG2F_H +#define LLVM_LIBC_SRC_MATH_LOG2F_H + +namespace __llvm_libc { + +float log2f(float x); + +} // namespace __llvm_libc + +#endif // LLVM_LIBC_SRC_MATH_LOG2F_H diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt --- a/libc/test/src/math/CMakeLists.txt +++ b/libc/test/src/math/CMakeLists.txt @@ -1194,6 +1194,19 @@ libc.src.__support.FPUtil.fputil ) +add_fp_unittest( + log2f_test + NEED_MPFR + SUITE + libc_math_unittests + SRCS + log2f_test.cpp + DEPENDS + libc.include.math + libc.src.math.log2f + libc.src.__support.FPUtil.fputil +) + add_subdirectory(generic) add_subdirectory(exhaustive) add_subdirectory(differential_testing) diff --git a/libc/test/src/math/differential_testing/CMakeLists.txt b/libc/test/src/math/differential_testing/CMakeLists.txt --- a/libc/test/src/math/differential_testing/CMakeLists.txt +++ b/libc/test/src/math/differential_testing/CMakeLists.txt @@ -233,6 +233,28 @@ -fno-builtin ) +add_diff_binary( + log2f_diff + SRCS + log2f_diff.cpp + DEPENDS + .single_input_single_output_diff + libc.src.math.log2f + COMPILE_OPTIONS + -fno-builtin +) + +add_diff_binary( + log2f_perf + SRCS + log2f_perf.cpp + DEPENDS + .single_input_single_output_diff + libc.src.math.log2f + COMPILE_OPTIONS + -fno-builtin +) + add_diff_binary( logf_diff SRCS diff --git a/libc/test/src/math/differential_testing/log2f_diff.cpp b/libc/test/src/math/differential_testing/log2f_diff.cpp new file mode 100644 --- /dev/null +++ b/libc/test/src/math/differential_testing/log2f_diff.cpp @@ -0,0 +1,16 @@ +//===-- Differential test for log2f ---------------------------------------===// +// +// 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 "SingleInputSingleOutputDiff.h" + +#include "src/math/log2f.h" + +#include + +SINGLE_INPUT_SINGLE_OUTPUT_DIFF(float, __llvm_libc::log2f, ::log2f, + "log2f_diff.log") diff --git a/libc/test/src/math/differential_testing/log2f_perf.cpp b/libc/test/src/math/differential_testing/log2f_perf.cpp new file mode 100644 --- /dev/null +++ b/libc/test/src/math/differential_testing/log2f_perf.cpp @@ -0,0 +1,16 @@ +//===-- Differential test for log2f ---------------------------------------===// +// +// 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 "SingleInputSingleOutputDiff.h" + +#include "src/math/log2f.h" + +#include + +SINGLE_INPUT_SINGLE_OUTPUT_PERF(float, __llvm_libc::log2f, ::log2f, + "log2f_perf.log") diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt --- a/libc/test/src/math/exhaustive/CMakeLists.txt +++ b/libc/test/src/math/exhaustive/CMakeLists.txt @@ -78,3 +78,20 @@ LINK_OPTIONS -lpthread ) + +add_fp_unittest( + log2f_test + NO_RUN_POSTBUILD + NEED_MPFR + SUITE + libc_math_exhaustive_tests + SRCS + log2f_test.cpp + DEPENDS + .exhaustive_test + libc.include.math + libc.src.math.log2f + libc.src.__support.FPUtil.fputil + LINK_OPTIONS + -lpthread +) diff --git a/libc/test/src/math/exhaustive/log2f_test.cpp b/libc/test/src/math/exhaustive/log2f_test.cpp new file mode 100644 --- /dev/null +++ b/libc/test/src/math/exhaustive/log2f_test.cpp @@ -0,0 +1,51 @@ +//===-- Exhaustive test for log2f -----------------------------------------===// +// +// 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 "exhaustive_test.h" +#include "src/__support/FPUtil/FPBits.h" +#include "src/math/log2f.h" +#include "utils/MPFRWrapper/MPFRUtils.h" +#include "utils/UnitTest/FPMatcher.h" + +using FPBits = __llvm_libc::fputil::FPBits; + +namespace mpfr = __llvm_libc::testing::mpfr; + +struct LlvmLibcLog2fExhaustiveTest : public LlvmLibcExhaustiveTest { + void check(uint32_t start, uint32_t stop, + mpfr::RoundingMode rounding) override { + mpfr::ForceRoundingMode r(rounding); + uint32_t bits = start; + do { + FPBits xbits(bits); + float x = float(xbits); + EXPECT_MPFR_MATCH(mpfr::Operation::Log2, x, __llvm_libc::log2f(x), 0.5, + rounding); + } while (bits++ < stop); + } +}; + +TEST_F(LlvmLibcLog2fExhaustiveTest, RoundNearestTieToEven) { + test_full_range(/*start=*/0U, /*stop=*/0x7f80'0000U, /*nthreads=*/16, + mpfr::RoundingMode::Nearest); +} + +TEST_F(LlvmLibcLog2fExhaustiveTest, RoundUp) { + test_full_range(/*start=*/0U, /*stop=*/0x7f80'0000U, /*nthreads=*/16, + mpfr::RoundingMode::Upward); +} + +TEST_F(LlvmLibcLog2fExhaustiveTest, RoundDown) { + test_full_range(/*start=*/0U, /*stop=*/0x7f80'0000U, /*nthreads=*/16, + mpfr::RoundingMode::Downward); +} + +TEST_F(LlvmLibcLog2fExhaustiveTest, RoundTowardZero) { + test_full_range(/*start=*/0U, /*stop=*/0x7f80'0000U, /*nthreads=*/16, + mpfr::RoundingMode::TowardZero); +} diff --git a/libc/test/src/math/log2f_test.cpp b/libc/test/src/math/log2f_test.cpp new file mode 100644 --- /dev/null +++ b/libc/test/src/math/log2f_test.cpp @@ -0,0 +1,64 @@ +//===-- Unittests for log2f -----------------------------------------------===// +// +// 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/__support/FPUtil/FPBits.h" +#include "src/math/log2f.h" +#include "utils/MPFRWrapper/MPFRUtils.h" +#include "utils/UnitTest/FPMatcher.h" +#include "utils/UnitTest/Test.h" +#include + +#include +#include + +namespace mpfr = __llvm_libc::testing::mpfr; + +DECLARE_SPECIAL_CONSTANTS(float) + +TEST(LlvmLibcLog2fTest, SpecialNumbers) { + EXPECT_FP_EQ(aNaN, __llvm_libc::log2f(aNaN)); + EXPECT_FP_EQ(inf, __llvm_libc::log2f(inf)); + EXPECT_TRUE(FPBits(__llvm_libc::log2f(neg_inf)).is_nan()); + EXPECT_FP_EQ(neg_inf, __llvm_libc::log2f(0.0f)); + EXPECT_FP_EQ(neg_inf, __llvm_libc::log2f(-0.0f)); + EXPECT_TRUE(FPBits(__llvm_libc::log2f(-1.0f)).is_nan()); + EXPECT_FP_EQ(zero, __llvm_libc::log2f(1.0f)); +} + +TEST(LlvmLibcLog2fTest, TrickyInputs) { + constexpr int N = 9; + constexpr uint32_t INPUTS[N] = {0x3f7d57f5U, 0x3f7ed848U, 0x3f7fd6ccU, + 0x3f7fffffU, 0x3f80079bU, 0x3f81d0b5U, + 0x3f82e602U, 0x3f83c98dU, 0x3f8cba39U}; + + for (int i = 0; i < N; ++i) { + float x = float(FPBits(INPUTS[i])); + EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log2, x, + __llvm_libc::log2f(x), 0.5); + } +} + +TEST(LlvmLibcLog2fTest, InFloatRange) { + constexpr uint32_t count = 1000000; + constexpr uint32_t step = UINT32_MAX / count; + for (uint32_t i = 0, v = 0; i <= count; ++i, v += step) { + float x = float(FPBits(v)); + if (isnan(x) || isinf(x)) + continue; + errno = 0; + float result = __llvm_libc::log2f(x); + // If the computation resulted in an error or did not produce valid result + // in the single-precision floating point range, then ignore comparing with + // MPFR result as MPFR can still produce valid results because of its + // wider precision. + if (isnan(result) || isinf(result) || errno != 0) + continue; + ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log2, x, + __llvm_libc::log2f(x), 0.5); + } +} diff --git a/libc/utils/MPFRWrapper/MPFRUtils.h b/libc/utils/MPFRWrapper/MPFRUtils.h --- a/libc/utils/MPFRWrapper/MPFRUtils.h +++ b/libc/utils/MPFRWrapper/MPFRUtils.h @@ -31,6 +31,7 @@ Expm1, Floor, Log, + Log2, Mod2PI, ModPIOver2, ModPIOver4, @@ -325,6 +326,23 @@ EXPECT_MPFR_MATCH_DEFAULT, GET_MPFR_DUMMY_ARG) \ (__VA_ARGS__) +#define EXPECT_MPFR_MATCH_ALL_ROUNDING(op, input, match_value, ulp_tolerance) \ + { \ + namespace mpfr = __llvm_libc::testing::mpfr; \ + mpfr::ForceRoundingMode __r1(mpfr::RoundingMode::Nearest); \ + EXPECT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::Nearest); \ + mpfr::ForceRoundingMode __r2(mpfr::RoundingMode::Upward); \ + EXPECT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::Upward); \ + mpfr::ForceRoundingMode __r3(mpfr::RoundingMode::Downward); \ + EXPECT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::Downward); \ + mpfr::ForceRoundingMode __r4(mpfr::RoundingMode::TowardZero); \ + EXPECT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::TowardZero); \ + } + #define ASSERT_MPFR_MATCH_DEFAULT(op, input, match_value, ulp_tolerance) \ ASSERT_THAT(match_value, \ __llvm_libc::testing::mpfr::get_mpfr_matcher( \ @@ -341,4 +359,21 @@ ASSERT_MPFR_MATCH_DEFAULT, GET_MPFR_DUMMY_ARG) \ (__VA_ARGS__) +#define ASSERT_MPFR_MATCH_ALL_ROUNDING(op, input, match_value, ulp_tolerance) \ + { \ + namespace mpfr = __llvm_libc::testing::mpfr; \ + mpfr::ForceRoundingMode __r1(mpfr::RoundingMode::Nearest); \ + ASSERT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::Nearest); \ + mpfr::ForceRoundingMode __r2(mpfr::RoundingMode::Upward); \ + ASSERT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::Upward); \ + mpfr::ForceRoundingMode __r3(mpfr::RoundingMode::Downward); \ + ASSERT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::Downward); \ + mpfr::ForceRoundingMode __r4(mpfr::RoundingMode::TowardZero); \ + ASSERT_MPFR_MATCH(op, input, match_value, ulp_tolerance, \ + mpfr::RoundingMode::TowardZero); \ + } + #endif // LLVM_LIBC_UTILS_TESTUTILS_MPFRUTILS_H diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp --- a/libc/utils/MPFRWrapper/MPFRUtils.cpp +++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp @@ -267,6 +267,12 @@ return result; } + MPFRNumber log2() const { + MPFRNumber result(*this); + mpfr_log2(result.value, value, mpfr_rounding); + return result; + } + MPFRNumber remquo(const MPFRNumber &divisor, int "ient) { MPFRNumber remainder(*this); long q; @@ -494,6 +500,8 @@ return mpfrInput.floor(); case Operation::Log: return mpfrInput.log(); + case Operation::Log2: + return mpfrInput.log2(); case Operation::Mod2PI: return mpfrInput.mod_2pi(); case Operation::ModPIOver2: