fdf20941a8
Add tests for signaling NaNs, and fix function behavior for handling signaling NaN input. Fixes https://github.com/llvm/llvm-project/issues/124812
222 lines
7.3 KiB
C++
222 lines
7.3 KiB
C++
//===-- Double-precision sincos function ----------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/math/sincos.h"
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#include "hdr/errno_macros.h"
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#include "src/__support/FPUtil/FEnvImpl.h"
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#include "src/__support/FPUtil/FPBits.h"
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#include "src/__support/FPUtil/double_double.h"
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#include "src/__support/FPUtil/dyadic_float.h"
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#include "src/__support/FPUtil/except_value_utils.h"
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#include "src/__support/FPUtil/multiply_add.h"
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#include "src/__support/FPUtil/rounding_mode.h"
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#include "src/__support/common.h"
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#include "src/__support/macros/config.h"
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#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
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#include "src/__support/macros/properties/cpu_features.h" // LIBC_TARGET_CPU_HAS_FMA
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#include "src/math/generic/range_reduction_double_common.h"
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#include "src/math/generic/sincos_eval.h"
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#ifdef LIBC_TARGET_CPU_HAS_FMA_DOUBLE
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#include "range_reduction_double_fma.h"
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#else
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#include "range_reduction_double_nofma.h"
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#endif // LIBC_TARGET_CPU_HAS_FMA_DOUBLE
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namespace LIBC_NAMESPACE_DECL {
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using DoubleDouble = fputil::DoubleDouble;
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using Float128 = typename fputil::DyadicFloat<128>;
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LLVM_LIBC_FUNCTION(void, sincos, (double x, double *sin_x, double *cos_x)) {
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using FPBits = typename fputil::FPBits<double>;
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FPBits xbits(x);
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uint16_t x_e = xbits.get_biased_exponent();
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DoubleDouble y;
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unsigned k;
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LargeRangeReduction range_reduction_large{};
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// |x| < 2^16
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if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT)) {
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// |x| < 2^-7
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if (LIBC_UNLIKELY(x_e < FPBits::EXP_BIAS - 7)) {
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// |x| < 2^-27
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if (LIBC_UNLIKELY(x_e < FPBits::EXP_BIAS - 27)) {
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// Signed zeros.
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if (LIBC_UNLIKELY(x == 0.0)) {
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*sin_x = x;
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*cos_x = 1.0;
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return;
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}
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// For |x| < 2^-27, max(|sin(x) - x|, |cos(x) - 1|) < ulp(x)/2.
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#ifdef LIBC_TARGET_CPU_HAS_FMA_DOUBLE
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*sin_x = fputil::multiply_add(x, -0x1.0p-54, x);
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*cos_x = fputil::multiply_add(x, -x, 1.0);
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#else
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*cos_x = fputil::round_result_slightly_down(1.0);
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if (LIBC_UNLIKELY(x_e < 4)) {
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int rounding_mode = fputil::quick_get_round();
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if (rounding_mode == FE_TOWARDZERO ||
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(xbits.sign() == Sign::POS && rounding_mode == FE_DOWNWARD) ||
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(xbits.sign() == Sign::NEG && rounding_mode == FE_UPWARD))
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*sin_x = FPBits(xbits.uintval() - 1).get_val();
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}
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*sin_x = fputil::multiply_add(x, -0x1.0p-54, x);
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#endif // LIBC_TARGET_CPU_HAS_FMA_DOUBLE
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return;
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}
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// No range reduction needed.
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k = 0;
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y.lo = 0.0;
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y.hi = x;
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} else {
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// Small range reduction.
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k = range_reduction_small(x, y);
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}
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} else {
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// Inf or NaN
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if (LIBC_UNLIKELY(x_e > 2 * FPBits::EXP_BIAS)) {
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if (xbits.is_signaling_nan()) {
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fputil::raise_except_if_required(FE_INVALID);
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*sin_x = *cos_x = FPBits::quiet_nan().get_val();
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return;
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}
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// sin(+-Inf) = NaN
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if (xbits.get_mantissa() == 0) {
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fputil::set_errno_if_required(EDOM);
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fputil::raise_except_if_required(FE_INVALID);
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}
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*sin_x = *cos_x = x + FPBits::quiet_nan().get_val();
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return;
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}
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// Large range reduction.
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k = range_reduction_large.fast(x, y);
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}
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DoubleDouble sin_y, cos_y;
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[[maybe_unused]] double err = generic::sincos_eval(y, sin_y, cos_y);
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// Look up sin(k * pi/128) and cos(k * pi/128)
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#ifdef LIBC_MATH_HAS_SMALL_TABLES
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// Memory saving versions. Use 65-entry table.
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auto get_idx_dd = [](unsigned kk) -> DoubleDouble {
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unsigned idx = (kk & 64) ? 64 - (kk & 63) : (kk & 63);
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DoubleDouble ans = SIN_K_PI_OVER_128[idx];
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if (kk & 128) {
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ans.hi = -ans.hi;
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ans.lo = -ans.lo;
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}
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return ans;
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};
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DoubleDouble sin_k = get_idx_dd(k);
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DoubleDouble cos_k = get_idx_dd(k + 64);
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#else
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// Fast look up version, but needs 256-entry table.
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// cos(k * pi/128) = sin(k * pi/128 + pi/2) = sin((k + 64) * pi/128).
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DoubleDouble sin_k = SIN_K_PI_OVER_128[k & 255];
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DoubleDouble cos_k = SIN_K_PI_OVER_128[(k + 64) & 255];
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#endif // LIBC_MATH_HAS_SMALL_TABLES
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DoubleDouble msin_k{-sin_k.lo, -sin_k.hi};
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// After range reduction, k = round(x * 128 / pi) and y = x - k * (pi / 128).
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// So k is an integer and -pi / 256 <= y <= pi / 256.
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// Then sin(x) = sin((k * pi/128 + y)
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// = sin(y) * cos(k*pi/128) + cos(y) * sin(k*pi/128)
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DoubleDouble sin_k_cos_y = fputil::quick_mult(cos_y, sin_k);
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DoubleDouble cos_k_sin_y = fputil::quick_mult(sin_y, cos_k);
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// cos(x) = cos((k * pi/128 + y)
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// = cos(y) * cos(k*pi/128) - sin(y) * sin(k*pi/128)
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DoubleDouble cos_k_cos_y = fputil::quick_mult(cos_y, cos_k);
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DoubleDouble msin_k_sin_y = fputil::quick_mult(sin_y, msin_k);
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DoubleDouble sin_dd =
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fputil::exact_add<false>(sin_k_cos_y.hi, cos_k_sin_y.hi);
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DoubleDouble cos_dd =
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fputil::exact_add<false>(cos_k_cos_y.hi, msin_k_sin_y.hi);
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sin_dd.lo += sin_k_cos_y.lo + cos_k_sin_y.lo;
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cos_dd.lo += msin_k_sin_y.lo + cos_k_cos_y.lo;
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#ifdef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
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*sin_x = sin_dd.hi + sin_dd.lo;
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*cos_x = cos_dd.hi + cos_dd.lo;
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return;
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#else
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// Accurate test and pass for correctly rounded implementation.
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double sin_lp = sin_dd.lo + err;
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double sin_lm = sin_dd.lo - err;
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double cos_lp = cos_dd.lo + err;
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double cos_lm = cos_dd.lo - err;
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double sin_upper = sin_dd.hi + sin_lp;
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double sin_lower = sin_dd.hi + sin_lm;
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double cos_upper = cos_dd.hi + cos_lp;
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double cos_lower = cos_dd.hi + cos_lm;
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// Ziv's rounding test.
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if (LIBC_LIKELY(sin_upper == sin_lower && cos_upper == cos_lower)) {
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*sin_x = sin_upper;
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*cos_x = cos_upper;
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return;
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}
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Float128 u_f128, sin_u, cos_u;
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if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT))
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u_f128 = range_reduction_small_f128(x);
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else
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u_f128 = range_reduction_large.accurate();
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generic::sincos_eval(u_f128, sin_u, cos_u);
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auto get_sin_k = [](unsigned kk) -> Float128 {
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unsigned idx = (kk & 64) ? 64 - (kk & 63) : (kk & 63);
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Float128 ans = SIN_K_PI_OVER_128_F128[idx];
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if (kk & 128)
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ans.sign = Sign::NEG;
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return ans;
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};
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// cos(k * pi/128) = sin(k * pi/128 + pi/2) = sin((k + 64) * pi/128).
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Float128 sin_k_f128 = get_sin_k(k);
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Float128 cos_k_f128 = get_sin_k(k + 64);
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Float128 msin_k_f128 = get_sin_k(k + 128);
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// TODO: Add assertion if Ziv's accuracy tests fail in debug mode.
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// https://github.com/llvm/llvm-project/issues/96452.
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if (sin_upper == sin_lower)
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*sin_x = sin_upper;
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else
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// sin(x) = sin((k * pi/128 + u)
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// = sin(u) * cos(k*pi/128) + cos(u) * sin(k*pi/128)
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*sin_x = static_cast<double>(
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fputil::quick_add(fputil::quick_mul(sin_k_f128, cos_u),
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fputil::quick_mul(cos_k_f128, sin_u)));
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if (cos_upper == cos_lower)
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*cos_x = cos_upper;
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else
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// cos(x) = cos((k * pi/128 + u)
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// = cos(u) * cos(k*pi/128) - sin(u) * sin(k*pi/128)
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*cos_x = static_cast<double>(
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fputil::quick_add(fputil::quick_mul(cos_k_f128, cos_u),
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fputil::quick_mul(msin_k_f128, sin_u)));
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#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
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}
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} // namespace LIBC_NAMESPACE_DECL
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