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[libc][math][c23] Add f16{add,sub}f C23 math functions (#96787)
Part of #93566.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,206 @@ | ||
| //===-- Add and subtract IEEE 754 floating-point numbers --------*- 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 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
|
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| #ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_ADD_SUB_H | ||
| #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_ADD_SUB_H | ||
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| #include "hdr/errno_macros.h" | ||
| #include "hdr/fenv_macros.h" | ||
| #include "src/__support/CPP/algorithm.h" | ||
| #include "src/__support/CPP/bit.h" | ||
| #include "src/__support/CPP/type_traits.h" | ||
| #include "src/__support/FPUtil/BasicOperations.h" | ||
| #include "src/__support/FPUtil/FEnvImpl.h" | ||
| #include "src/__support/FPUtil/FPBits.h" | ||
| #include "src/__support/FPUtil/dyadic_float.h" | ||
| #include "src/__support/FPUtil/rounding_mode.h" | ||
| #include "src/__support/macros/attributes.h" | ||
| #include "src/__support/macros/optimization.h" | ||
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| namespace LIBC_NAMESPACE::fputil::generic { | ||
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| template <bool IsSub, typename OutType, typename InType> | ||
| LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> && | ||
| cpp::is_floating_point_v<InType> && | ||
| sizeof(OutType) <= sizeof(InType), | ||
| OutType> | ||
| add_or_sub(InType x, InType y) { | ||
| using OutFPBits = FPBits<OutType>; | ||
| using OutStorageType = typename OutFPBits::StorageType; | ||
| using InFPBits = FPBits<InType>; | ||
| using InStorageType = typename InFPBits::StorageType; | ||
|
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| constexpr int GUARD_BITS_LEN = 3; | ||
| constexpr int RESULT_FRACTION_LEN = InFPBits::FRACTION_LEN + GUARD_BITS_LEN; | ||
| constexpr int RESULT_MANTISSA_LEN = RESULT_FRACTION_LEN + 1; | ||
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| using DyadicFloat = | ||
| DyadicFloat<cpp::bit_ceil(static_cast<size_t>(RESULT_MANTISSA_LEN))>; | ||
|
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| InFPBits x_bits(x); | ||
| InFPBits y_bits(y); | ||
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| bool is_effectively_add = (x_bits.sign() == y_bits.sign()) != IsSub; | ||
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| if (LIBC_UNLIKELY(x_bits.is_inf_or_nan() || y_bits.is_inf_or_nan() || | ||
| x_bits.is_zero() || y_bits.is_zero())) { | ||
| if (x_bits.is_nan() || y_bits.is_nan()) { | ||
| if (x_bits.is_signaling_nan() || y_bits.is_signaling_nan()) | ||
| raise_except_if_required(FE_INVALID); | ||
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| if (x_bits.is_quiet_nan()) { | ||
| InStorageType x_payload = static_cast<InStorageType>(getpayload(x)); | ||
| if ((x_payload & ~(OutFPBits::FRACTION_MASK >> 1)) == 0) | ||
| return OutFPBits::quiet_nan(x_bits.sign(), | ||
| static_cast<OutStorageType>(x_payload)) | ||
| .get_val(); | ||
| } | ||
|
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| if (y_bits.is_quiet_nan()) { | ||
| InStorageType y_payload = static_cast<InStorageType>(getpayload(y)); | ||
| if ((y_payload & ~(OutFPBits::FRACTION_MASK >> 1)) == 0) | ||
| return OutFPBits::quiet_nan(y_bits.sign(), | ||
| static_cast<OutStorageType>(y_payload)) | ||
| .get_val(); | ||
| } | ||
|
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| return OutFPBits::quiet_nan().get_val(); | ||
| } | ||
|
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| if (x_bits.is_inf()) { | ||
| if (y_bits.is_inf()) { | ||
| if (!is_effectively_add) { | ||
| raise_except_if_required(FE_INVALID); | ||
| return OutFPBits::quiet_nan().get_val(); | ||
| } | ||
|
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| return OutFPBits::inf(x_bits.sign()).get_val(); | ||
| } | ||
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| return OutFPBits::inf(x_bits.sign()).get_val(); | ||
| } | ||
|
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| if (y_bits.is_inf()) | ||
| return OutFPBits::inf(y_bits.sign()).get_val(); | ||
|
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| if (x_bits.is_zero()) { | ||
| if (y_bits.is_zero()) { | ||
| switch (quick_get_round()) { | ||
| case FE_DOWNWARD: | ||
| return OutFPBits::zero(Sign::NEG).get_val(); | ||
| default: | ||
| return OutFPBits::zero(Sign::POS).get_val(); | ||
| } | ||
| } | ||
|
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| // volatile prevents Clang from converting tmp to OutType and then | ||
| // immediately back to InType before negating it, resulting in double | ||
| // rounding. | ||
| volatile InType tmp = y; | ||
| if constexpr (IsSub) | ||
| tmp = -tmp; | ||
| return static_cast<OutType>(tmp); | ||
| } | ||
|
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| if (y_bits.is_zero()) { | ||
| volatile InType tmp = y; | ||
| if constexpr (IsSub) | ||
| tmp = -tmp; | ||
| return static_cast<OutType>(tmp); | ||
| } | ||
| } | ||
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| InType x_abs = x_bits.abs().get_val(); | ||
| InType y_abs = y_bits.abs().get_val(); | ||
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| if (x_abs == y_abs && !is_effectively_add) { | ||
| switch (quick_get_round()) { | ||
| case FE_DOWNWARD: | ||
| return OutFPBits::zero(Sign::NEG).get_val(); | ||
| default: | ||
| return OutFPBits::zero(Sign::POS).get_val(); | ||
| } | ||
| } | ||
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| Sign result_sign = Sign::POS; | ||
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| if (x_abs > y_abs) { | ||
| result_sign = x_bits.sign(); | ||
| } else if (x_abs < y_abs) { | ||
| if (is_effectively_add) | ||
| result_sign = y_bits.sign(); | ||
| else if (y_bits.is_pos()) | ||
| result_sign = Sign::NEG; | ||
| } else if (is_effectively_add) { | ||
| result_sign = x_bits.sign(); | ||
| } | ||
|
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| InFPBits max_bits(cpp::max(x_abs, y_abs)); | ||
| InFPBits min_bits(cpp::min(x_abs, y_abs)); | ||
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| InStorageType result_mant; | ||
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| if (max_bits.is_subnormal()) { | ||
| // min_bits must be subnormal too. | ||
|
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| if (is_effectively_add) | ||
| result_mant = max_bits.get_mantissa() + min_bits.get_mantissa(); | ||
| else | ||
| result_mant = max_bits.get_mantissa() - min_bits.get_mantissa(); | ||
|
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| result_mant <<= GUARD_BITS_LEN; | ||
| } else { | ||
| InStorageType max_mant = max_bits.get_explicit_mantissa() << GUARD_BITS_LEN; | ||
| InStorageType min_mant = min_bits.get_explicit_mantissa() << GUARD_BITS_LEN; | ||
| int alignment = | ||
| max_bits.get_biased_exponent() - min_bits.get_biased_exponent(); | ||
|
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| InStorageType aligned_min_mant = | ||
| min_mant >> cpp::min(alignment, RESULT_MANTISSA_LEN); | ||
| bool aligned_min_mant_sticky; | ||
|
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| if (alignment <= 3) | ||
| aligned_min_mant_sticky = false; | ||
| else if (alignment <= InFPBits::FRACTION_LEN + 3) | ||
| aligned_min_mant_sticky = | ||
| (min_mant << (InFPBits::STORAGE_LEN - alignment)) != 0; | ||
| else | ||
| aligned_min_mant_sticky = true; | ||
|
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| if (is_effectively_add) | ||
| result_mant = max_mant + (aligned_min_mant | aligned_min_mant_sticky); | ||
| else | ||
| result_mant = max_mant - (aligned_min_mant | aligned_min_mant_sticky); | ||
| } | ||
|
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| int result_exp = max_bits.get_exponent() - RESULT_FRACTION_LEN; | ||
| DyadicFloat result(result_sign, result_exp, result_mant); | ||
| return result.template as<OutType, /*ShouldSignalExceptions=*/true>(); | ||
| } | ||
|
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| template <typename OutType, typename InType> | ||
| LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> && | ||
| cpp::is_floating_point_v<InType> && | ||
| sizeof(OutType) <= sizeof(InType), | ||
| OutType> | ||
| add(InType x, InType y) { | ||
| return add_or_sub</*IsSub=*/false, OutType>(x, y); | ||
| } | ||
|
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| template <typename OutType, typename InType> | ||
| LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> && | ||
| cpp::is_floating_point_v<InType> && | ||
| sizeof(OutType) <= sizeof(InType), | ||
| OutType> | ||
| sub(InType x, InType y) { | ||
| return add_or_sub</*IsSub=*/true, OutType>(x, y); | ||
| } | ||
|
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| } // namespace LIBC_NAMESPACE::fputil::generic | ||
|
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| #endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_ADD_SUB_H |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,20 @@ | ||
| //===-- Implementation header for f16addf -----------------------*- 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 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
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| #ifndef LLVM_LIBC_SRC_MATH_F16ADDF_H | ||
| #define LLVM_LIBC_SRC_MATH_F16ADDF_H | ||
|
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| #include "src/__support/macros/properties/types.h" | ||
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| namespace LIBC_NAMESPACE { | ||
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| float16 f16addf(float x, float y); | ||
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| } // namespace LIBC_NAMESPACE | ||
|
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| #endif // LLVM_LIBC_SRC_MATH_F16ADDF_H |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,20 @@ | ||
| //===-- Implementation header for f16subf -----------------------*- 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 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
|
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| #ifndef LLVM_LIBC_SRC_MATH_F16SUBF_H | ||
| #define LLVM_LIBC_SRC_MATH_F16SUBF_H | ||
|
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| #include "src/__support/macros/properties/types.h" | ||
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| namespace LIBC_NAMESPACE { | ||
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| float16 f16subf(float x, float y); | ||
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| } // namespace LIBC_NAMESPACE | ||
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| #endif // LLVM_LIBC_SRC_MATH_F16SUBF_H |
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