llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-libc Author: Muhammad Bassiouni (bassiounix) <details> <summary>Changes</summary> Part of #<!-- -->147386 in preparation for: https://discourse.llvm.org/t/rfc-make-clang-builtin-math-functions-constexpr-with-llvm-libc-to-support-c-23-constexpr-math-functions/86450 --- Full diff: https://github.com/llvm/llvm-project/pull/150854.diff 9 Files Affected: - (modified) libc/shared/math.h (+1) - (added) libc/shared/math/atanf.h (+23) - (modified) libc/src/__support/math/CMakeLists.txt (+15) - (added) libc/src/__support/math/atanf.h (+129) - (modified) libc/src/math/generic/CMakeLists.txt (+1-8) - (modified) libc/src/math/generic/atanf.cpp (+2-108) - (modified) libc/test/shared/CMakeLists.txt (+1) - (modified) libc/test/shared/shared_math_test.cpp (+1) - (modified) utils/bazel/llvm-project-overlay/libc/BUILD.bazel (+15-7) ``````````diff diff --git a/libc/shared/math.h b/libc/shared/math.h index 70b1b7b0bef09..21536647948f4 100644 --- a/libc/shared/math.h +++ b/libc/shared/math.h @@ -23,6 +23,7 @@ #include "math/asinhf.h" #include "math/asinhf16.h" #include "math/atan.h" +#include "math/atanf.h" #include "math/erff.h" #include "math/exp.h" #include "math/exp10.h" diff --git a/libc/shared/math/atanf.h b/libc/shared/math/atanf.h new file mode 100644 index 0000000000000..858d727bd6698 --- /dev/null +++ b/libc/shared/math/atanf.h @@ -0,0 +1,23 @@ +//===-- Shared atanf function -----------------------------------*- 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_SHARED_MATH_ATANF_H +#define LLVM_LIBC_SHARED_MATH_ATANF_H + +#include "shared/libc_common.h" +#include "src/__support/math/atanf.h" + +namespace LIBC_NAMESPACE_DECL { +namespace shared { + +using math::atanf; + +} // namespace shared +} // namespace LIBC_NAMESPACE_DECL + +#endif // LLVM_LIBC_SHARED_MATH_ATANF_H diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt index cc02920c2a1ef..95acc962cc885 100644 --- a/libc/src/__support/math/CMakeLists.txt +++ b/libc/src/__support/math/CMakeLists.txt @@ -199,6 +199,21 @@ DEPENDS libc.src.__support.macros.optimization ) +add_header_library( + atanf + HDRS + atanf.h + DEPENDS + .inv_trigf_utils + libc.src.__support.FPUtil.except_value_utils + libc.src.__support.FPUtil.fp_bits + libc.src.__support.FPUtil.multiply_add + libc.src.__support.FPUtil.nearest_integer + libc.src.__support.FPUtil.polyeval + libc.src.__support.FPUtil.rounding_mode + libc.src.__support.macros.optimization +) + add_header_library( asinf HDRS diff --git a/libc/src/__support/math/atanf.h b/libc/src/__support/math/atanf.h new file mode 100644 index 0000000000000..92799dc8db3cc --- /dev/null +++ b/libc/src/__support/math/atanf.h @@ -0,0 +1,129 @@ +//===-- Implementation header for atanf -------------------------*- 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___SUPPORT_MATH_ATANF_H +#define LLVM_LIBC_SRC___SUPPORT_MATH_ATANF_H + +#include "inv_trigf_utils.h" +#include "src/__support/FPUtil/FPBits.h" +#include "src/__support/FPUtil/PolyEval.h" +#include "src/__support/FPUtil/except_value_utils.h" +#include "src/__support/FPUtil/multiply_add.h" +#include "src/__support/FPUtil/nearest_integer.h" +#include "src/__support/macros/config.h" +#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY + +namespace LIBC_NAMESPACE_DECL { + +namespace math { + +LIBC_INLINE static constexpr float atanf(float x) { + using namespace inv_trigf_utils_internal; + using FPBits = typename fputil::FPBits<float>; + + constexpr double FINAL_SIGN[2] = {1.0, -1.0}; + constexpr double SIGNED_PI_OVER_2[2] = {0x1.921fb54442d18p0, + -0x1.921fb54442d18p0}; + + FPBits x_bits(x); + Sign sign = x_bits.sign(); + x_bits.set_sign(Sign::POS); + uint32_t x_abs = x_bits.uintval(); + + // x is inf or nan, |x| < 2^-4 or |x|= > 16. + if (LIBC_UNLIKELY(x_abs <= 0x3d80'0000U || x_abs >= 0x4180'0000U)) { + double x_d = static_cast<double>(x); + double const_term = 0.0; + if (LIBC_UNLIKELY(x_abs >= 0x4180'0000)) { + // atan(+-Inf) = +-pi/2. + if (x_bits.is_inf()) { + volatile double sign_pi_over_2 = SIGNED_PI_OVER_2[sign.is_neg()]; + return static_cast<float>(sign_pi_over_2); + } + if (x_bits.is_nan()) + return x; + // x >= 16 + x_d = -1.0 / x_d; + const_term = SIGNED_PI_OVER_2[sign.is_neg()]; + } + // 0 <= x < 1/16; + if (LIBC_UNLIKELY(x_bits.is_zero())) + return x; + // x <= 2^-12; + if (LIBC_UNLIKELY(x_abs < 0x3980'0000)) { +#if defined(LIBC_TARGET_CPU_HAS_FMA_FLOAT) + return fputil::multiply_add(x, -0x1.0p-25f, x); +#else + double x_d = static_cast<double>(x); + return static_cast<float>(fputil::multiply_add(x_d, -0x1.0p-25, x_d)); +#endif // LIBC_TARGET_CPU_HAS_FMA_FLOAT + } + // Use Taylor polynomial: + // atan(x) ~ x * (1 - x^2 / 3 + x^4 / 5 - x^6 / 7 + x^8 / 9 - x^10 / 11). + constexpr double ATAN_TAYLOR[6] = { + 0x1.0000000000000p+0, -0x1.5555555555555p-2, 0x1.999999999999ap-3, + -0x1.2492492492492p-3, 0x1.c71c71c71c71cp-4, -0x1.745d1745d1746p-4, + }; + double x2 = x_d * x_d; + double x4 = x2 * x2; + double c0 = fputil::multiply_add(x2, ATAN_TAYLOR[1], ATAN_TAYLOR[0]); + double c1 = fputil::multiply_add(x2, ATAN_TAYLOR[3], ATAN_TAYLOR[2]); + double c2 = fputil::multiply_add(x2, ATAN_TAYLOR[5], ATAN_TAYLOR[4]); + double p = fputil::polyeval(x4, c0, c1, c2); + double r = fputil::multiply_add(x_d, p, const_term); + return static_cast<float>(r); + } + + // Range reduction steps: + // 1) atan(x) = sign(x) * atan(|x|) + // 2) If |x| > 1, atan(|x|) = pi/2 - atan(1/|x|) + // 3) For 1/16 < x <= 1, we find k such that: |x - k/16| <= 1/32. + // 4) Then we use polynomial approximation: + // atan(x) ~ atan((k/16) + (x - (k/16)) * Q(x - k/16) + // = P(x - k/16) + double x_d = 0, const_term = 0, final_sign = 0; + int idx = 0; + + if (x_abs > 0x3f80'0000U) { + // |x| > 1, we need to invert x, so we will perform range reduction in + // double precision. + x_d = 1.0 / static_cast<double>(x_bits.get_val()); + double k_d = fputil::nearest_integer(x_d * 0x1.0p4); + x_d = fputil::multiply_add(k_d, -0x1.0p-4, x_d); + idx = static_cast<int>(k_d); + final_sign = FINAL_SIGN[sign.is_pos()]; + // Adjust constant term of the polynomial by +- pi/2. + const_term = fputil::multiply_add(final_sign, ATAN_COEFFS[idx][0], + SIGNED_PI_OVER_2[sign.is_neg()]); + } else { + // Exceptional value: + if (LIBC_UNLIKELY(x_abs == 0x3d8d'6b23U)) { // |x| = 0x1.1ad646p-4 + return sign.is_pos() ? fputil::round_result_slightly_down(0x1.1a6386p-4f) + : fputil::round_result_slightly_up(-0x1.1a6386p-4f); + } + // Perform range reduction in single precision. + float x_f = x_bits.get_val(); + float k_f = fputil::nearest_integer(x_f * 0x1.0p4f); + x_f = fputil::multiply_add(k_f, -0x1.0p-4f, x_f); + x_d = static_cast<double>(x_f); + idx = static_cast<int>(k_f); + final_sign = FINAL_SIGN[sign.is_neg()]; + const_term = final_sign * ATAN_COEFFS[idx][0]; + } + + double p = atan_eval(x_d, idx); + double r = fputil::multiply_add(final_sign * x_d, p, const_term); + + return static_cast<float>(r); +} + +} // namespace math + +} // namespace LIBC_NAMESPACE_DECL + +#endif // LLVM_LIBC_SRC___SUPPORT_MATH_ATANF_H diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt index ffb0d06c434fc..196e00841f2d1 100644 --- a/libc/src/math/generic/CMakeLists.txt +++ b/libc/src/math/generic/CMakeLists.txt @@ -4014,14 +4014,7 @@ add_entrypoint_object( HDRS ../atanf.h DEPENDS - libc.src.__support.FPUtil.except_value_utils - libc.src.__support.FPUtil.fp_bits - libc.src.__support.FPUtil.multiply_add - libc.src.__support.FPUtil.nearest_integer - libc.src.__support.FPUtil.polyeval - libc.src.__support.FPUtil.rounding_mode - libc.src.__support.macros.optimization - libc.src.__support.math.inv_trigf_utils + libc.src.__support.math.atanf ) add_entrypoint_object( diff --git a/libc/src/math/generic/atanf.cpp b/libc/src/math/generic/atanf.cpp index 22f962ef4cce4..acd32f09abb95 100644 --- a/libc/src/math/generic/atanf.cpp +++ b/libc/src/math/generic/atanf.cpp @@ -7,116 +7,10 @@ //===----------------------------------------------------------------------===// #include "src/math/atanf.h" -#include "src/__support/FPUtil/FPBits.h" -#include "src/__support/FPUtil/PolyEval.h" -#include "src/__support/FPUtil/except_value_utils.h" -#include "src/__support/FPUtil/multiply_add.h" -#include "src/__support/FPUtil/nearest_integer.h" -#include "src/__support/FPUtil/rounding_mode.h" -#include "src/__support/macros/config.h" -#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY -#include "src/__support/math/inv_trigf_utils.h" +#include "src/__support/math/atanf.h" namespace LIBC_NAMESPACE_DECL { -LLVM_LIBC_FUNCTION(float, atanf, (float x)) { - using namespace inv_trigf_utils_internal; - using FPBits = typename fputil::FPBits<float>; - - constexpr double FINAL_SIGN[2] = {1.0, -1.0}; - constexpr double SIGNED_PI_OVER_2[2] = {0x1.921fb54442d18p0, - -0x1.921fb54442d18p0}; - - FPBits x_bits(x); - Sign sign = x_bits.sign(); - x_bits.set_sign(Sign::POS); - uint32_t x_abs = x_bits.uintval(); - - // x is inf or nan, |x| < 2^-4 or |x|= > 16. - if (LIBC_UNLIKELY(x_abs <= 0x3d80'0000U || x_abs >= 0x4180'0000U)) { - double x_d = static_cast<double>(x); - double const_term = 0.0; - if (LIBC_UNLIKELY(x_abs >= 0x4180'0000)) { - // atan(+-Inf) = +-pi/2. - if (x_bits.is_inf()) { - volatile double sign_pi_over_2 = SIGNED_PI_OVER_2[sign.is_neg()]; - return static_cast<float>(sign_pi_over_2); - } - if (x_bits.is_nan()) - return x; - // x >= 16 - x_d = -1.0 / x_d; - const_term = SIGNED_PI_OVER_2[sign.is_neg()]; - } - // 0 <= x < 1/16; - if (LIBC_UNLIKELY(x_bits.is_zero())) - return x; - // x <= 2^-12; - if (LIBC_UNLIKELY(x_abs < 0x3980'0000)) { -#if defined(LIBC_TARGET_CPU_HAS_FMA_FLOAT) - return fputil::multiply_add(x, -0x1.0p-25f, x); -#else - double x_d = static_cast<double>(x); - return static_cast<float>(fputil::multiply_add(x_d, -0x1.0p-25, x_d)); -#endif // LIBC_TARGET_CPU_HAS_FMA_FLOAT - } - // Use Taylor polynomial: - // atan(x) ~ x * (1 - x^2 / 3 + x^4 / 5 - x^6 / 7 + x^8 / 9 - x^10 / 11). - constexpr double ATAN_TAYLOR[6] = { - 0x1.0000000000000p+0, -0x1.5555555555555p-2, 0x1.999999999999ap-3, - -0x1.2492492492492p-3, 0x1.c71c71c71c71cp-4, -0x1.745d1745d1746p-4, - }; - double x2 = x_d * x_d; - double x4 = x2 * x2; - double c0 = fputil::multiply_add(x2, ATAN_TAYLOR[1], ATAN_TAYLOR[0]); - double c1 = fputil::multiply_add(x2, ATAN_TAYLOR[3], ATAN_TAYLOR[2]); - double c2 = fputil::multiply_add(x2, ATAN_TAYLOR[5], ATAN_TAYLOR[4]); - double p = fputil::polyeval(x4, c0, c1, c2); - double r = fputil::multiply_add(x_d, p, const_term); - return static_cast<float>(r); - } - - // Range reduction steps: - // 1) atan(x) = sign(x) * atan(|x|) - // 2) If |x| > 1, atan(|x|) = pi/2 - atan(1/|x|) - // 3) For 1/16 < x <= 1, we find k such that: |x - k/16| <= 1/32. - // 4) Then we use polynomial approximation: - // atan(x) ~ atan((k/16) + (x - (k/16)) * Q(x - k/16) - // = P(x - k/16) - double x_d, const_term, final_sign; - int idx; - - if (x_abs > 0x3f80'0000U) { - // |x| > 1, we need to invert x, so we will perform range reduction in - // double precision. - x_d = 1.0 / static_cast<double>(x_bits.get_val()); - double k_d = fputil::nearest_integer(x_d * 0x1.0p4); - x_d = fputil::multiply_add(k_d, -0x1.0p-4, x_d); - idx = static_cast<int>(k_d); - final_sign = FINAL_SIGN[sign.is_pos()]; - // Adjust constant term of the polynomial by +- pi/2. - const_term = fputil::multiply_add(final_sign, ATAN_COEFFS[idx][0], - SIGNED_PI_OVER_2[sign.is_neg()]); - } else { - // Exceptional value: - if (LIBC_UNLIKELY(x_abs == 0x3d8d'6b23U)) { // |x| = 0x1.1ad646p-4 - return sign.is_pos() ? fputil::round_result_slightly_down(0x1.1a6386p-4f) - : fputil::round_result_slightly_up(-0x1.1a6386p-4f); - } - // Perform range reduction in single precision. - float x_f = x_bits.get_val(); - float k_f = fputil::nearest_integer(x_f * 0x1.0p4f); - x_f = fputil::multiply_add(k_f, -0x1.0p-4f, x_f); - x_d = static_cast<double>(x_f); - idx = static_cast<int>(k_f); - final_sign = FINAL_SIGN[sign.is_neg()]; - const_term = final_sign * ATAN_COEFFS[idx][0]; - } - - double p = atan_eval(x_d, idx); - double r = fputil::multiply_add(final_sign * x_d, p, const_term); - - return static_cast<float>(r); -} +LLVM_LIBC_FUNCTION(float, atanf, (float x)) { return math::atanf(x); } } // namespace LIBC_NAMESPACE_DECL diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt index 3227a78f01c8d..6d0601feda138 100644 --- a/libc/test/shared/CMakeLists.txt +++ b/libc/test/shared/CMakeLists.txt @@ -19,6 +19,7 @@ add_fp_unittest( libc.src.__support.math.asinhf libc.src.__support.math.asinhf16 libc.src.__support.math.atan + libc.src.__support.math.atanf libc.src.__support.math.erff libc.src.__support.math.exp libc.src.__support.math.exp10 diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp index 07eaeda130363..228fa42ec834e 100644 --- a/libc/test/shared/shared_math_test.cpp +++ b/libc/test/shared/shared_math_test.cpp @@ -44,6 +44,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat) { EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::acoshf(1.0f)); EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::asinf(0.0f)); EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::asinhf(0.0f)); + EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::atanf(0.0f)); EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::erff(0.0f)); EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::exp10f(0.0f)); EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::expf(0.0f)); diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel index 86975cc8da954..e8c59fa87d4c3 100644 --- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel +++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel @@ -2274,6 +2274,20 @@ libc_support_library( ], ) +libc_support_library( + name = "__support_math_atanf", + hdrs = ["src/__support/math/atanf.h"], + deps = [ + ":__support_fputil_except_value_utils", + ":__support_fputil_multiply_add", + ":__support_fputil_nearest_integer", + ":__support_fputil_polyeval", + ":__support_fputil_rounding_mode", + ":__support_macros_optimization", + ":__support_math_inv_trigf_utils", + ], +) + libc_support_library( name = "__support_math_asinf", hdrs = ["src/__support/math/asinf.h"], @@ -2886,13 +2900,7 @@ libc_math_function( libc_math_function( name = "atanf", additional_deps = [ - ":__support_fputil_fma", - ":__support_fputil_multiply_add", - ":__support_fputil_nearest_integer", - ":__support_fputil_polyeval", - ":__support_fputil_rounding_mode", - ":__support_macros_optimization", - ":__support_math_inv_trigf_utils", + ":__support_math_atanf" ], ) `````````` </details> https://github.com/llvm/llvm-project/pull/150854 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
