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Revert "[libc][NFC] Refactor FPBits and remove LongDoubleBits specialization (#78192)" (#78329)

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This reverts commit fdbf255c96.

Causes build breakage on 32b arm (see reports:
https://github.com/llvm/llvm-project/pull/78192).

These are reproducible for the 32b arm baremetal target on x86 hosts as
well.
This commit is contained in:
Nick Desaulniers 2024-01-16 12:09:58 -08:00 committed by GitHub
parent 184784690d
commit 337b771592
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
8 changed files with 282 additions and 618 deletions
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443
libc/src/__support/FPUtil/FPBits.h
View File

@ -31,40 +31,6 @@ enum class FPType {
X86_Binary80,
};
// The classes hierarchy is as follows:
//
// ┌───────────────────┐
// │ FPLayout<FPType> │
// └─────────▲─────────┘
// │
// ┌─────────┴─────────┐
// │ FPRepBase<FPType> │
// └─────────▲─────────┘
// │
// ┌────────────┴─────────────┐
// │ │
// ┌────────┴──────┐ ┌─────────────┴──────────────┐
// │ FPRep<FPType> │ │ FPRep<FPType::X86_Binary80 │
// └────────▲──────┘ └─────────────▲──────────────┘
// │ │
// └────────────┬─────────────┘
// │
// ┌─────┴─────┐
// │ FPBits<T> │
// └───────────┘
//
// - 'FPLayout' defines only a few constants, namely the 'StorageType' and the
// length of the sign, the exponent and significand parts.
// - 'FPRepBase' builds more constants on top of those from 'FPLayout' like
// exponent bias, shifts and masks. It also defines tools to assemble or test
// these parts.
// - 'FPRep' defines functions to interact with the floating point
// representation. The default implementation is the one for 'IEEE754', a
// specialization is provided for X86 Extended Precision that has a different
// encoding.
// - 'FPBits' is templated on the platform floating point types. Contrary to
// 'FPRep' that is platform agnostic 'FPBits' is architecture dependent.
namespace internal {
// Defines the layout (sign, exponent, significand) of a floating point type in
@ -166,94 +132,11 @@ public:
static_assert((SIG_MASK & EXP_MASK & SIGN_MASK) == 0, "masks disjoint");
static_assert((SIG_MASK | EXP_MASK | SIGN_MASK) == FP_MASK, "masks cover");
protected:
private:
LIBC_INLINE static constexpr StorageType bit_at(int position) {
return StorageType(1) << position;
}
// An opaque type to store a floating point exponent.
// We define special values but it is valid to create arbitrary values as long
// as they are in the range [MIN, MAX].
enum class Exponent : int32_t {
MIN = 1 - EXP_BIAS,
ZERO = 0,
MAX = EXP_BIAS,
};
// An opaque type to store a floating point biased exponent.
// We define special values but it is valid to create arbitrary values as long
// as they are in the range [BITS_ALL_ZEROES, BITS_ALL_ONES].
// Values greater than BITS_ALL_ONES are truncated.
enum class BiasedExponent : uint32_t {
// The exponent value for denormal numbers.
BITS_ALL_ZEROES = 0,
// The exponent value for infinity.
BITS_ALL_ONES = 2 * EXP_BIAS + 1,
};
LIBC_INLINE static constexpr BiasedExponent biased(Exponent value) {
return static_cast<BiasedExponent>(static_cast<int32_t>(value) + EXP_BIAS);
}
// An opaque type to store a floating point significand.
// We define special values but it is valid to create arbitrary values as long
// as they are in the range [BITS_ALL_ZEROES, BITS_ALL_ONES].
// Note that the semantics of the Significand are implementation dependent.
// Values greater than BITS_ALL_ONES are truncated.
enum class Significand : StorageType {
ZERO = 0,
LSB = 1,
MSB = bit_at(SIG_LEN - 1),
// Aliases
BITS_ALL_ZEROES = ZERO,
BITS_ALL_ONES = SIG_MASK,
};
template <typename T>
LIBC_INLINE static constexpr auto storage_cast(T value) {
return static_cast<StorageType>(value);
}
LIBC_INLINE friend constexpr Significand operator|(const Significand a,
const Significand b) {
return Significand{storage_cast(storage_cast(a) | storage_cast(b))};
}
LIBC_INLINE friend constexpr Significand operator^(const Significand a,
const Significand b) {
return Significand{storage_cast(storage_cast(a) ^ storage_cast(b))};
}
LIBC_INLINE friend constexpr Significand operator>>(const Significand a,
int shift) {
return Significand{storage_cast(storage_cast(a) >> shift)};
}
LIBC_INLINE static constexpr StorageType encode(BiasedExponent exp) {
return (storage_cast(exp) << SIG_LEN) & EXP_MASK;
}
LIBC_INLINE static constexpr StorageType encode(Significand value) {
return storage_cast(value) & SIG_MASK;
}
LIBC_INLINE static constexpr StorageType encode(BiasedExponent exp,
Significand sig) {
return encode(exp) | encode(sig);
}
LIBC_INLINE static constexpr StorageType encode(bool sign, BiasedExponent exp,
Significand sig) {
if (sign)
return SIGN_MASK | encode(exp, sig);
return encode(exp, sig);
}
LIBC_INLINE constexpr StorageType exp_bits() const { return bits & EXP_MASK; }
LIBC_INLINE constexpr StorageType sig_bits() const { return bits & SIG_MASK; }
LIBC_INLINE constexpr StorageType exp_sig_bits() const {
return bits & EXP_SIG_MASK;
}
private:
// Merge bits from 'a' and 'b' values according to 'mask'.
// Use 'a' bits when corresponding 'mask' bits are zeroes and 'b' bits when
// corresponding bits are ones.
@ -272,6 +155,20 @@ protected:
LIBC_INLINE_VAR static constexpr StorageType FRACTION_MASK =
mask_trailing_ones<StorageType, FRACTION_LEN>();
// If a number x is a NAN, then it is a quiet NAN if:
// QUIET_NAN_MASK & bits(x) != 0
LIBC_INLINE_VAR static constexpr StorageType QUIET_NAN_MASK =
fp_type == FPType::X86_Binary80
? bit_at(SIG_LEN - 1) | bit_at(SIG_LEN - 2) // 0b1100...
: bit_at(SIG_LEN - 1); // 0b1000...
// Mask to generate a default signaling NAN. Any NAN that is not
// a quiet NAN is considered a signaling NAN.
LIBC_INLINE_VAR static constexpr StorageType DEFAULT_SIGNALING_NAN =
fp_type == FPType::X86_Binary80
? bit_at(SIG_LEN - 1) | bit_at(SIG_LEN - 3) // 0b1010...
: bit_at(SIG_LEN - 2); // 0b0100...
// The floating point number representation as an unsigned integer.
StorageType bits = 0;
@ -323,9 +220,6 @@ public:
}
LIBC_INLINE constexpr StorageType uintval() const { return bits & FP_MASK; }
LIBC_INLINE constexpr void set_uintval(StorageType value) {
bits = (value & FP_MASK);
}
LIBC_INLINE constexpr bool is_zero() const {
return (bits & EXP_SIG_MASK) == 0;
@ -347,213 +241,6 @@ template <FPType fp_type> struct FPRep : public FPRepBase<fp_type> {
using UP::FRACTION_LEN;
using UP::FRACTION_MASK;
using UP::MANTISSA_PRECISION;
protected:
using typename UP::BiasedExponent;
using typename UP::Exponent;
using typename UP::Significand;
using UP::biased;
using UP::encode;
using UP::exp_bits;
using UP::exp_sig_bits;
using UP::sig_bits;
public:
LIBC_INLINE constexpr bool is_nan() const {
return exp_sig_bits() >
encode(BiasedExponent::BITS_ALL_ONES, Significand::ZERO);
}
LIBC_INLINE constexpr bool is_quiet_nan() const {
return exp_sig_bits() >=
encode(BiasedExponent::BITS_ALL_ONES, Significand::MSB);
}
LIBC_INLINE constexpr bool is_signaling_nan() const {
return is_nan() && !is_quiet_nan();
}
LIBC_INLINE constexpr bool is_inf() const {
return exp_sig_bits() ==
encode(BiasedExponent::BITS_ALL_ONES, Significand::ZERO);
}
LIBC_INLINE constexpr bool is_zero() const {
return exp_sig_bits() ==
encode(BiasedExponent::BITS_ALL_ZEROES, Significand::ZERO);
}
LIBC_INLINE constexpr bool is_finite() const {
return exp_bits() != encode(BiasedExponent::BITS_ALL_ONES);
}
LIBC_INLINE
constexpr bool is_subnormal() const {
return exp_bits() == encode(BiasedExponent::BITS_ALL_ZEROES);
}
LIBC_INLINE constexpr bool is_normal() const {
return is_finite() && !is_subnormal();
}
LIBC_INLINE static constexpr StorageType zero(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ZEROES, Significand::ZERO);
}
LIBC_INLINE static constexpr StorageType one(bool sign = false) {
return encode(sign, biased(Exponent::ZERO), Significand::ZERO);
}
LIBC_INLINE static constexpr StorageType min_subnormal(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ZEROES, Significand::LSB);
}
LIBC_INLINE static constexpr StorageType max_subnormal(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ZEROES,
Significand::BITS_ALL_ONES);
}
LIBC_INLINE static constexpr StorageType min_normal(bool sign = false) {
return encode(sign, biased(Exponent::MIN), Significand::ZERO);
}
LIBC_INLINE static constexpr StorageType max_normal(bool sign = false) {
return encode(sign, biased(Exponent::MAX), Significand::BITS_ALL_ONES);
}
LIBC_INLINE static constexpr StorageType inf(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ONES, Significand::ZERO);
}
LIBC_INLINE static constexpr StorageType build_nan(bool sign = false,
StorageType v = 0) {
return encode(sign, BiasedExponent::BITS_ALL_ONES,
(v ? Significand{v} : (Significand::MSB >> 1)));
}
LIBC_INLINE static constexpr StorageType build_quiet_nan(bool sign = false,
StorageType v = 0) {
return encode(sign, BiasedExponent::BITS_ALL_ONES,
Significand::MSB | Significand{v});
}
// The function return mantissa with the implicit bit set iff the current
// value is a valid normal number.
LIBC_INLINE constexpr StorageType get_explicit_mantissa() {
if (is_subnormal())
return sig_bits();
return (StorageType(1) << UP::SIG_LEN) | sig_bits();
}
};
// Specialization for the X86 Extended Precision type.
template <>
struct FPRep<FPType::X86_Binary80> : public FPRepBase<FPType::X86_Binary80> {
using UP = FPRepBase<FPType::X86_Binary80>;
using typename UP::StorageType;
using UP::FRACTION_LEN;
using UP::FRACTION_MASK;
using UP::MANTISSA_PRECISION;
protected:
using typename UP::BiasedExponent;
using typename UP::Significand;
using UP::encode;
public:
// The x86 80 bit float represents the leading digit of the mantissa
// explicitly. This is the mask for that bit.
static constexpr StorageType EXPLICIT_BIT_MASK = StorageType(1)
<< FRACTION_LEN;
// The X80 significand is made of an explicit bit and the fractional part.
static_assert((EXPLICIT_BIT_MASK & FRACTION_MASK) == 0,
"the explicit bit and the fractional part should not overlap");
static_assert((EXPLICIT_BIT_MASK | FRACTION_MASK) == SIG_MASK,
"the explicit bit and the fractional part should cover the "
"whole significand");
LIBC_INLINE constexpr bool is_nan() const {
// Most encoding forms from the table found in
// https://en.wikipedia.org/wiki/Extended_precision#x86_extended_precision_format
// are interpreted as NaN.
// More precisely :
// - Pseudo-Infinity
// - Pseudo Not a Number
// - Signalling Not a Number
// - Floating-point Indefinite
// - Quiet Not a Number
// - Unnormal
// This can be reduced to the following logic:
if (exp_bits() == encode(BiasedExponent::BITS_ALL_ONES))
return !is_inf();
if (exp_bits() != encode(BiasedExponent::BITS_ALL_ZEROES))
return (sig_bits() & encode(Significand::MSB)) == 0;
return false;
}
LIBC_INLINE constexpr bool is_quiet_nan() const {
return exp_sig_bits() >= encode(BiasedExponent::BITS_ALL_ONES,
Significand::MSB | (Significand::MSB >> 1));
}
LIBC_INLINE constexpr bool is_signaling_nan() const {
return is_nan() && !is_quiet_nan();
}
LIBC_INLINE constexpr bool is_inf() const {
return exp_sig_bits() ==
encode(BiasedExponent::BITS_ALL_ONES, Significand::MSB);
}
LIBC_INLINE constexpr bool is_zero() const {
return exp_sig_bits() ==
encode(BiasedExponent::BITS_ALL_ZEROES, Significand::ZERO);
}
LIBC_INLINE constexpr bool is_finite() const {
return !is_inf() && !is_nan();
}
LIBC_INLINE
constexpr bool is_subnormal() const {
return exp_sig_bits() >
encode(BiasedExponent::BITS_ALL_ZEROES, Significand::ZERO);
}
LIBC_INLINE constexpr bool is_normal() const {
const auto exp = exp_bits();
if (exp == encode(BiasedExponent::BITS_ALL_ZEROES) ||
exp == encode(BiasedExponent::BITS_ALL_ONES))
return false;
return get_implicit_bit();
}
LIBC_INLINE static constexpr StorageType zero(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ZEROES, Significand::ZERO);
}
LIBC_INLINE static constexpr StorageType one(bool sign = false) {
return encode(sign, biased(Exponent::ZERO), Significand::MSB);
}
LIBC_INLINE static constexpr StorageType min_subnormal(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ZEROES, Significand::LSB);
}
LIBC_INLINE static constexpr StorageType max_subnormal(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ZEROES,
Significand::BITS_ALL_ONES ^ Significand::MSB);
}
LIBC_INLINE static constexpr StorageType min_normal(bool sign = false) {
return encode(sign, biased(Exponent::MIN), Significand::MSB);
}
LIBC_INLINE static constexpr StorageType max_normal(bool sign = false) {
return encode(sign, biased(Exponent::MAX), Significand::BITS_ALL_ONES);
}
LIBC_INLINE static constexpr StorageType inf(bool sign = false) {
return encode(sign, BiasedExponent::BITS_ALL_ONES, Significand::MSB);
}
LIBC_INLINE static constexpr StorageType build_nan(bool sign = false,
StorageType v = 0) {
return encode(sign, BiasedExponent::BITS_ALL_ONES,
Significand::MSB |
(v ? Significand{v} : (Significand::MSB >> 2)));
}
LIBC_INLINE static constexpr StorageType build_quiet_nan(bool sign = false,
StorageType v = 0) {
return encode(sign, BiasedExponent::BITS_ALL_ONES,
Significand::MSB | (Significand::MSB >> 1) | Significand{v});
}
LIBC_INLINE constexpr StorageType get_explicit_mantissa() const {
return sig_bits();
}
// The following functions are specific to FPRep<FPType::X86_Binary80>.
// TODO: Remove if possible.
LIBC_INLINE constexpr bool get_implicit_bit() const {
return bits & EXPLICIT_BIT_MASK;
}
LIBC_INLINE constexpr void set_implicit_bit(bool implicitVal) {
if (get_implicit_bit() != implicitVal)
bits ^= EXPLICIT_BIT_MASK;
}
};
} // namespace internal
@ -589,29 +276,47 @@ template <typename T> LIBC_INLINE static constexpr FPType get_fp_type() {
static_assert(cpp::always_false<UnqualT>, "Unsupported type");
}
// A generic class to represent floating point formats.
// A generic class to represent single precision, double precision, and quad
// precision IEEE 754 floating point formats.
// On most platforms, the 'float' type corresponds to single precision floating
// point numbers, the 'double' type corresponds to double precision floating
// point numers, and the 'long double' type corresponds to the quad precision
// floating numbers. On x86 platforms however, the 'long double' type maps to
// an x87 floating point format.
// an x87 floating point format. This format is an IEEE 754 extension format.
// It is handled as an explicit specialization of this class.
template <typename T> struct FPBits : public internal::FPRep<get_fp_type<T>()> {
static_assert(cpp::is_floating_point_v<T>,
"FPBits instantiated with invalid type.");
using UP = internal::FPRep<get_fp_type<T>()>;
using Rep = UP;
using StorageType = typename UP::StorageType;
private:
using UP::EXP_SIG_MASK;
using UP::QUIET_NAN_MASK;
using UP::SIG_LEN;
using UP::SIG_MASK;
public:
using StorageType = typename UP::StorageType;
using UP::bits;
using UP::EXP_BIAS;
using UP::EXP_LEN;
using UP::EXP_MASK;
using UP::EXP_MASK_SHIFT;
using UP::FRACTION_LEN;
using UP::FRACTION_MASK;
using UP::SIGN_MASK;
using UP::TOTAL_LEN;
using UP::UP;
using UP::get_biased_exponent;
using UP::is_zero;
// Constants.
static constexpr int MAX_BIASED_EXPONENT = (1 << EXP_LEN) - 1;
static constexpr StorageType MIN_NORMAL = UP::min_normal(false);
static constexpr StorageType MAX_NORMAL = UP::max_normal(false);
static constexpr StorageType MIN_SUBNORMAL = UP::min_subnormal(false);
static constexpr StorageType MAX_SUBNORMAL = UP::max_subnormal(false);
static constexpr StorageType MIN_SUBNORMAL = StorageType(1);
static constexpr StorageType MAX_SUBNORMAL = FRACTION_MASK;
static constexpr StorageType MIN_NORMAL = (StorageType(1) << FRACTION_LEN);
static constexpr StorageType MAX_NORMAL =
(StorageType(MAX_BIASED_EXPONENT - 1) << SIG_LEN) | SIG_MASK;
// Constructors.
LIBC_INLINE constexpr FPBits() = default;
@ -633,56 +338,88 @@ template <typename T> struct FPBits : public internal::FPRep<get_fp_type<T>()> {
LIBC_INLINE constexpr explicit operator T() const { return get_val(); }
LIBC_INLINE constexpr bool is_inf_or_nan() const { return !UP::is_finite(); }
// The function return mantissa with the implicit bit set iff the current
// value is a valid normal number.
LIBC_INLINE constexpr StorageType get_explicit_mantissa() {
return ((get_biased_exponent() > 0 && !is_inf_or_nan())
? (FRACTION_MASK + 1)
: 0) |
(FRACTION_MASK & bits);
}
LIBC_INLINE constexpr bool is_inf() const {
return (bits & EXP_SIG_MASK) == EXP_MASK;
}
LIBC_INLINE constexpr bool is_nan() const {
return (bits & EXP_SIG_MASK) > EXP_MASK;
}
LIBC_INLINE constexpr bool is_quiet_nan() const {
return (bits & EXP_SIG_MASK) >= (EXP_MASK | QUIET_NAN_MASK);
}
LIBC_INLINE constexpr bool is_inf_or_nan() const {
return (bits & EXP_MASK) == EXP_MASK;
}
LIBC_INLINE constexpr FPBits abs() const {
return FPBits(bits & UP::EXP_SIG_MASK);
return FPBits(bits & EXP_SIG_MASK);
}
// Methods below this are used by tests.
LIBC_INLINE static constexpr T zero(bool sign = false) {
return FPBits(UP::zero(sign)).get_val();
StorageType rep = (sign ? SIGN_MASK : StorageType(0)) // sign
| 0 // exponent
| 0; // mantissa
return FPBits(rep).get_val();
}
LIBC_INLINE static constexpr T neg_zero() { return zero(true); }
LIBC_INLINE static constexpr T inf(bool sign = false) {
return FPBits(UP::inf(sign)).get_val();
StorageType rep = (sign ? SIGN_MASK : StorageType(0)) // sign
| EXP_MASK // exponent
| 0; // mantissa
return FPBits(rep).get_val();
}
LIBC_INLINE static constexpr T neg_inf() { return inf(true); }
LIBC_INLINE static constexpr T min_normal() {
return FPBits(UP::min_normal(false)).get_val();
return FPBits(MIN_NORMAL).get_val();
}
LIBC_INLINE static constexpr T max_normal() {
return FPBits(UP::max_normal(false)).get_val();
return FPBits(MAX_NORMAL).get_val();
}
LIBC_INLINE static constexpr T min_denormal() {
return FPBits(UP::min_subnormal(false)).get_val();
return FPBits(MIN_SUBNORMAL).get_val();
}
LIBC_INLINE static constexpr T max_denormal() {
return FPBits(UP::max_subnormal(false)).get_val();
return FPBits(MAX_SUBNORMAL).get_val();
}
LIBC_INLINE static constexpr T build_nan(StorageType v) {
return FPBits(UP::build_nan(false, v)).get_val();
StorageType rep = 0 // sign
| EXP_MASK // exponent
| (v & FRACTION_MASK); // mantissa
return FPBits(rep).get_val();
}
LIBC_INLINE static constexpr T build_quiet_nan(StorageType v) {
return FPBits(UP::build_quiet_nan(false, v)).get_val();
return build_nan(QUIET_NAN_MASK | v);
}
LIBC_INLINE static constexpr FPBits<T>
create_value(bool sign, StorageType biased_exp, StorageType mantissa) {
static_assert(get_fp_type<T>() != FPType::X86_Binary80,
"This function is not tested for X86 Extended Precision");
return FPBits(UP::encode(sign, typename UP::BiasedExponent(biased_exp),
typename UP::Significand(mantissa)));
StorageType rep = (sign ? SIGN_MASK : StorageType(0)) // sign
| ((biased_exp << EXP_MASK_SHIFT) & EXP_MASK) // exponent
| (mantissa & FRACTION_MASK); // mantissa
return FPBits(rep);
}
// The function convert integer number and unbiased exponent to proper float
@ -697,8 +434,6 @@ template <typename T> struct FPBits : public internal::FPRep<get_fp_type<T>()> {
// 5) Number is unsigned, so the result can be only positive.
LIBC_INLINE static constexpr FPBits<T> make_value(StorageType number,
int ep) {
static_assert(get_fp_type<T>() != FPType::X86_Binary80,
"This function is not tested for X86 Extended Precision");
FPBits<T> result;
// offset: +1 for sign, but -1 for implicit first bit
int lz = cpp::countl_zero(number) - EXP_LEN;
@ -719,4 +454,8 @@ template <typename T> struct FPBits : public internal::FPRep<get_fp_type<T>()> {
} // namespace fputil
} // namespace LIBC_NAMESPACE
#ifdef LIBC_LONG_DOUBLE_IS_X86_FLOAT80
#include "x86_64/LongDoubleBits.h"
#endif
#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_FPBITS_H

2
libc/src/__support/FPUtil/generic/sqrt_80_bit_long_double.h
View File

@ -131,7 +131,7 @@ LIBC_INLINE long double sqrt(long double x) {
out.set_implicit_bit(1);
out.set_mantissa((y & (ONE - 1)));
return out.get_val();
return out;
}
}
#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80

179
libc/src/__support/FPUtil/x86_64/LongDoubleBits.h Normal file
View File

@ -0,0 +1,179 @@
//===-- Bit representation of x86 long double 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_X86_64_LONGDOUBLEBITS_H
#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_X86_64_LONGDOUBLEBITS_H
#include "src/__support/CPP/bit.h"
#include "src/__support/UInt128.h"
#include "src/__support/common.h"
#include "src/__support/macros/attributes.h" // LIBC_INLINE
#include "src/__support/macros/properties/architectures.h"
#if !defined(LIBC_TARGET_ARCH_IS_X86)
#error "Invalid include"
#endif
#include "src/__support/FPUtil/FPBits.h"
#include <stdint.h>
namespace LIBC_NAMESPACE {
namespace fputil {
template <>
struct FPBits<long double> : public internal::FPRep<FPType::X86_Binary80> {
using UP = internal::FPRep<FPType::X86_Binary80>;
using StorageType = typename UP::StorageType;
private:
using UP::bits;
using UP::EXP_SIG_MASK;
using UP::QUIET_NAN_MASK;
public:
// Constants.
static constexpr int MAX_BIASED_EXPONENT = (1 << EXP_LEN) - 1;
// The x86 80 bit float represents the leading digit of the mantissa
// explicitly. This is the mask for that bit.
static constexpr StorageType EXPLICIT_BIT_MASK = StorageType(1)
<< FRACTION_LEN;
// The X80 significand is made of an explicit bit and the fractional part.
static_assert((EXPLICIT_BIT_MASK & FRACTION_MASK) == 0,
"the explicit bit and the fractional part should not overlap");
static_assert((EXPLICIT_BIT_MASK | FRACTION_MASK) == SIG_MASK,
"the explicit bit and the fractional part should cover the "
"whole significand");
static constexpr StorageType MIN_SUBNORMAL = StorageType(1);
// Subnormal numbers include the implicit bit in x86 long double formats.
static constexpr StorageType MAX_SUBNORMAL = FRACTION_MASK;
static constexpr StorageType MIN_NORMAL =
(StorageType(1) << SIG_LEN) | EXPLICIT_BIT_MASK;
static constexpr StorageType MAX_NORMAL =
(StorageType(MAX_BIASED_EXPONENT - 1) << SIG_LEN) | SIG_MASK;
// Constructors.
LIBC_INLINE constexpr FPBits() = default;
template <typename XType> LIBC_INLINE constexpr explicit FPBits(XType x) {
using Unqual = typename cpp::remove_cv_t<XType>;
if constexpr (cpp::is_same_v<Unqual, long double>) {
bits = cpp::bit_cast<StorageType>(x);
} else if constexpr (cpp::is_same_v<Unqual, StorageType>) {
bits = x;
} else {
// We don't want accidental type promotions/conversions, so we require
// exact type match.
static_assert(cpp::always_false<XType>);
}
}
// Floating-point conversions.
LIBC_INLINE constexpr long double get_val() const {
return cpp::bit_cast<long double>(bits);
}
LIBC_INLINE constexpr operator long double() const {
return cpp::bit_cast<long double>(bits);
}
LIBC_INLINE constexpr StorageType get_explicit_mantissa() const {
return bits & SIG_MASK;
}
LIBC_INLINE constexpr bool get_implicit_bit() const {
return bits & EXPLICIT_BIT_MASK;
}
LIBC_INLINE constexpr void set_implicit_bit(bool implicitVal) {
if (get_implicit_bit() != implicitVal)
bits ^= EXPLICIT_BIT_MASK;
}
LIBC_INLINE constexpr bool is_inf() const {
return get_biased_exponent() == MAX_BIASED_EXPONENT &&
get_mantissa() == 0 && get_implicit_bit() == 1;
}
LIBC_INLINE constexpr bool is_nan() const {
if (get_biased_exponent() == MAX_BIASED_EXPONENT) {
return (get_implicit_bit() == 0) || get_mantissa() != 0;
} else if (get_biased_exponent() != 0) {
return get_implicit_bit() == 0;
}
return false;
}
LIBC_INLINE constexpr bool is_inf_or_nan() const {
return (get_biased_exponent() == MAX_BIASED_EXPONENT) ||
(get_biased_exponent() != 0 && get_implicit_bit() == 0);
}
LIBC_INLINE constexpr bool is_quiet_nan() const {
return (bits & EXP_SIG_MASK) >= (EXP_MASK | QUIET_NAN_MASK);
}
// Methods below this are used by tests.
LIBC_INLINE static constexpr long double zero(bool sign = false) {
StorageType rep = (sign ? SIGN_MASK : StorageType(0)) // sign
| 0 // exponent
| 0 // explicit bit
| 0; // mantissa
return FPBits(rep).get_val();
}
LIBC_INLINE static constexpr long double neg_zero() { return zero(true); }
LIBC_INLINE static constexpr long double inf(bool sign = false) {
StorageType rep = (sign ? SIGN_MASK : StorageType(0)) // sign
| EXP_MASK // exponent
| EXPLICIT_BIT_MASK // explicit bit
| 0; // mantissa
return FPBits(rep).get_val();
}
LIBC_INLINE static constexpr long double neg_inf() { return inf(true); }
LIBC_INLINE static constexpr long double min_normal() {
return FPBits(MIN_NORMAL).get_val();
}
LIBC_INLINE static constexpr long double max_normal() {
return FPBits(MAX_NORMAL).get_val();
}
LIBC_INLINE static constexpr long double min_denormal() {
return FPBits(MIN_SUBNORMAL).get_val();
}
LIBC_INLINE static constexpr long double max_denormal() {
return FPBits(MAX_SUBNORMAL).get_val();
}
LIBC_INLINE static constexpr long double build_nan(StorageType v) {
StorageType rep = 0 // sign
| EXP_MASK // exponent
| EXPLICIT_BIT_MASK // explicit bit
| (v & FRACTION_MASK); // mantissa
return FPBits(rep).get_val();
}
LIBC_INLINE static constexpr long double build_quiet_nan(StorageType v) {
return build_nan(QUIET_NAN_MASK | v);
}
};
static_assert(
sizeof(FPBits<long double>) == sizeof(long double),
"Internal long double representation does not match the machine format.");
} // namespace fputil
} // namespace LIBC_NAMESPACE
#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_X86_64_LONGDOUBLEBITS_H

8
libc/src/__support/FPUtil/x86_64/NextAfterLongDouble.h
View File

@ -61,7 +61,7 @@ LIBC_INLINE long double nextafter(long double from, long double to) {
from_bits.set_biased_exponent(from_bits.get_biased_exponent() + 1);
if (from_bits.is_inf())
raise_except_if_required(FE_OVERFLOW | FE_INEXACT);
return from_bits.get_val();
return from_bits;
} else {
++int_val;
}
@ -75,7 +75,7 @@ LIBC_INLINE long double nextafter(long double from, long double to) {
// from == 0 is handled separately so decrementing the exponent will not
// lead to underflow.
from_bits.set_biased_exponent(from_bits.get_biased_exponent() - 1);
return from_bits.get_val();
return from_bits;
} else {
--int_val;
}
@ -94,7 +94,7 @@ LIBC_INLINE long double nextafter(long double from, long double to) {
// from == 0 is handled separately so decrementing the exponent will not
// lead to underflow.
from_bits.set_biased_exponent(from_bits.get_biased_exponent() - 1);
return from_bits.get_val();
return from_bits;
} else {
--int_val;
}
@ -109,7 +109,7 @@ LIBC_INLINE long double nextafter(long double from, long double to) {
from_bits.set_biased_exponent(from_bits.get_biased_exponent() + 1);
if (from_bits.is_inf())
raise_except_if_required(FE_OVERFLOW | FE_INEXACT);
return from_bits.get_val();
return from_bits;
} else {
++int_val;
}

213
libc/test/src/__support/FPUtil/fpbits_test.cpp
View File

@ -12,219 +12,6 @@
using LIBC_NAMESPACE::fputil::FPBits;
TEST(LlvmLibcFPBitsTest, FPType_IEEE754_Binary16) {
using LIBC_NAMESPACE::fputil::FPType;
using LIBC_NAMESPACE::fputil::internal::FPRep;
using Rep = FPRep<FPType::IEEE754_Binary16>;
using u16 = uint16_t;
EXPECT_EQ(u16(0b0'00000'0000000000), Rep::zero());
EXPECT_EQ(u16(0b0'01111'0000000000), Rep::one());
EXPECT_EQ(u16(0b0'00000'0000000001), Rep::min_subnormal());
EXPECT_EQ(u16(0b0'00000'1111111111), Rep::max_subnormal());
EXPECT_EQ(u16(0b0'00001'0000000000), Rep::min_normal());
EXPECT_EQ(u16(0b0'11110'1111111111), Rep::max_normal());
EXPECT_EQ(u16(0b0'11111'0000000000), Rep::inf());
EXPECT_EQ(u16(0b0'11111'0100000000), Rep::build_nan());
EXPECT_EQ(u16(0b0'11111'1000000000), Rep::build_quiet_nan());
}
TEST(LlvmLibcFPBitsTest, FPType_IEEE754_Binary32) {
using LIBC_NAMESPACE::fputil::FPType;
using LIBC_NAMESPACE::fputil::internal::FPRep;
using Rep = FPRep<FPType::IEEE754_Binary32>;
using u32 = uint32_t;
EXPECT_EQ(u32(0b0'00000000'00000000000000000000000), Rep::zero());
EXPECT_EQ(u32(0b0'01111111'00000000000000000000000), Rep::one());
EXPECT_EQ(u32(0b0'00000000'00000000000000000000001), Rep::min_subnormal());
EXPECT_EQ(u32(0b0'00000000'11111111111111111111111), Rep::max_subnormal());
EXPECT_EQ(u32(0b0'00000001'00000000000000000000000), Rep::min_normal());
EXPECT_EQ(u32(0b0'11111110'11111111111111111111111), Rep::max_normal());
EXPECT_EQ(u32(0b0'11111111'00000000000000000000000), Rep::inf());
EXPECT_EQ(u32(0b0'11111111'01000000000000000000000), Rep::build_nan());
EXPECT_EQ(u32(0b0'11111111'10000000000000000000000), Rep::build_quiet_nan());
}
TEST(LlvmLibcFPBitsTest, FPType_IEEE754_Binary64) {
using LIBC_NAMESPACE::fputil::FPType;
using LIBC_NAMESPACE::fputil::internal::FPRep;
using Rep = FPRep<FPType::IEEE754_Binary64>;
using u64 = uint64_t;
EXPECT_EQ(
u64(0b0'00000000000'0000000000000000000000000000000000000000000000000000),
Rep::zero());
EXPECT_EQ(
u64(0b0'01111111111'0000000000000000000000000000000000000000000000000000),
Rep::one());
EXPECT_EQ(
u64(0b0'00000000000'0000000000000000000000000000000000000000000000000001),
Rep::min_subnormal());
EXPECT_EQ(
u64(0b0'00000000000'1111111111111111111111111111111111111111111111111111),
Rep::max_subnormal());
EXPECT_EQ(
u64(0b0'00000000001'0000000000000000000000000000000000000000000000000000),
Rep::min_normal());
EXPECT_EQ(
u64(0b0'11111111110'1111111111111111111111111111111111111111111111111111),
Rep::max_normal());
EXPECT_EQ(
u64(0b0'11111111111'0000000000000000000000000000000000000000000000000000),
Rep::inf());
EXPECT_EQ(
u64(0b0'11111111111'0100000000000000000000000000000000000000000000000000),
Rep::build_nan());
EXPECT_EQ(
u64(0b0'11111111111'1000000000000000000000000000000000000000000000000000),
Rep::build_quiet_nan());
}
static constexpr UInt128 u128(uint64_t hi, uint64_t lo) {
#if defined(__SIZEOF_INT128__)
return __uint128_t(hi) << 64 | __uint128_t(lo);
#else
return UInt128({hi, lo});
#endif
}
TEST(LlvmLibcFPBitsTest, FPType_X86_Binary80) {
using LIBC_NAMESPACE::fputil::FPType;
using LIBC_NAMESPACE::fputil::internal::FPRep;
using Rep = FPRep<FPType::X86_Binary80>;
EXPECT_EQ(
u128(0b0'000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::zero());
EXPECT_EQ(
u128(0b0'011111111111111,
0b1000000000000000000000000000000000000000000000000000000000000000),
Rep::one());
EXPECT_EQ(
u128(0b0'000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000001),
Rep::min_subnormal());
EXPECT_EQ(
u128(0b0'000000000000000,
0b0111111111111111111111111111111111111111111111111111111111111111),
Rep::max_subnormal());
EXPECT_EQ(
u128(0b0'000000000000001,
0b1000000000000000000000000000000000000000000000000000000000000000),
Rep::min_normal());
EXPECT_EQ(
u128(0b0'111111111111110,
0b1111111111111111111111111111111111111111111111111111111111111111),
Rep::max_normal());
EXPECT_EQ(
u128(0b0'111111111111111,
0b1000000000000000000000000000000000000000000000000000000000000000),
Rep::inf());
EXPECT_EQ(
u128(0b0'111111111111111,
0b1010000000000000000000000000000000000000000000000000000000000000),
Rep::build_nan());
EXPECT_EQ(
u128(0b0'111111111111111,
0b1100000000000000000000000000000000000000000000000000000000000000),
Rep::build_quiet_nan());
}
TEST(LlvmLibcFPBitsTest, FPType_X86_Binary80_IsNan) {
using LIBC_NAMESPACE::fputil::FPType;
using LIBC_NAMESPACE::fputil::internal::FPRep;
using Rep = FPRep<FPType::X86_Binary80>;
const auto is_nan = [](uint64_t hi, uint64_t lo) {
Rep rep;
rep.set_uintval(u128(hi, lo));
return rep.is_nan();
};
EXPECT_TRUE(is_nan(
0b0'111111111111111, // NAN : Pseudo-Infinity
0b0000000000000000000000000000000000000000000000000000000000000000));
EXPECT_TRUE(is_nan(
0b0'111111111111111, // NAN : Pseudo Not a Number
0b0000000000000000000000000000000000000000000000000000000000000001));
EXPECT_TRUE(is_nan(
0b0'111111111111111, // NAN : Pseudo Not a Number
0b0100000000000000000000000000000000000000000000000000000000000000));
EXPECT_TRUE(is_nan(
0b0'111111111111111, // NAN : Signalling Not a Number
0b1000000000000000000000000000000000000000000000000000000000000001));
EXPECT_TRUE(is_nan(
0b0'111111111111111, // NAN : Floating-point Indefinite
0b1100000000000000000000000000000000000000000000000000000000000000));
EXPECT_TRUE(is_nan(
0b0'111111111111111, // NAN : Quiet Not a Number
0b1100000000000000000000000000000000000000000000000000000000000001));
EXPECT_TRUE(is_nan(
0b0'111111111111110, // NAN : Unnormal
0b0000000000000000000000000000000000000000000000000000000000000000));
EXPECT_FALSE(is_nan(
0b0'000000000000000, // Zero
0b0000000000000000000000000000000000000000000000000000000000000000));
EXPECT_FALSE(is_nan(
0b0'000000000000000, // Subnormal
0b0000000000000000000000000000000000000000000000000000000000000001));
EXPECT_FALSE(is_nan(
0b0'000000000000000, // Pseudo Denormal
0b1000000000000000000000000000000000000000000000000000000000000001));
EXPECT_FALSE(is_nan(
0b0'111111111111111, // Infinity
0b1000000000000000000000000000000000000000000000000000000000000000));
EXPECT_FALSE(is_nan(
0b0'111111111111110, // Normalized
0b1000000000000000000000000000000000000000000000000000000000000000));
}
TEST(LlvmLibcFPBitsTest, FPType_IEEE754_Binary128) {
using LIBC_NAMESPACE::fputil::FPType;
using LIBC_NAMESPACE::fputil::internal::FPRep;
using Rep = FPRep<FPType::IEEE754_Binary128>;
EXPECT_EQ(
u128(0b0'000000000000000'000000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::zero());
EXPECT_EQ(
u128(0b0'011111111111111'000000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::one());
EXPECT_EQ(
u128(0b0'000000000000000'000000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000001),
Rep::min_subnormal());
EXPECT_EQ(
u128(0b0'000000000000000'111111111111111111111111111111111111111111111111,
0b1111111111111111111111111111111111111111111111111111111111111111),
Rep::max_subnormal());
EXPECT_EQ(
u128(0b0'000000000000001'000000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::min_normal());
EXPECT_EQ(
u128(0b0'111111111111110'111111111111111111111111111111111111111111111111,
0b1111111111111111111111111111111111111111111111111111111111111111),
Rep::max_normal());
EXPECT_EQ(
u128(0b0'111111111111111'000000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::inf());
EXPECT_EQ(
u128(0b0'111111111111111'010000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::build_nan());
EXPECT_EQ(
u128(0b0'111111111111111'100000000000000000000000000000000000000000000000,
0b0000000000000000000000000000000000000000000000000000000000000000),
Rep::build_quiet_nan());
}
TEST(LlvmLibcFPBitsTest, FloatType) {
using FloatBits = FPBits<float>;

12
libc/test/utils/FPUtil/x86_long_double_test.cpp
View File

@ -27,7 +27,7 @@ TEST(LlvmLibcX86LongDoubleTest, is_nan) {
// If exponent has the max value and the implicit bit is 0,
// then the number is a NaN for all values of mantissa.
bits.set_mantissa(i);
long double nan = bits.get_val();
long double nan = bits;
ASSERT_NE(static_cast<int>(isnan(nan)), 0);
ASSERT_TRUE(bits.is_nan());
}
@ -38,7 +38,7 @@ TEST(LlvmLibcX86LongDoubleTest, is_nan) {
// then the number is a NaN for all non-zero values of mantissa.
// Note the initial value of |i| of 1 to avoid a zero mantissa.
bits.set_mantissa(i);
long double nan = bits.get_val();
long double nan = bits;
ASSERT_NE(static_cast<int>(isnan(nan)), 0);
ASSERT_TRUE(bits.is_nan());
}
@ -49,7 +49,7 @@ TEST(LlvmLibcX86LongDoubleTest, is_nan) {
// If exponent is non-zero and also not max, and the implicit bit is 0,
// then the number is a NaN for all values of mantissa.
bits.set_mantissa(i);
long double nan = bits.get_val();
long double nan = bits;
ASSERT_NE(static_cast<int>(isnan(nan)), 0);
ASSERT_TRUE(bits.is_nan());
}
@ -60,7 +60,7 @@ TEST(LlvmLibcX86LongDoubleTest, is_nan) {
// If exponent is non-zero and also not max, and the implicit bit is 1,
// then the number is normal value for all values of mantissa.
bits.set_mantissa(i);
long double valid = bits.get_val();
long double valid = bits;
ASSERT_EQ(static_cast<int>(isnan(valid)), 0);
ASSERT_FALSE(bits.is_nan());
}
@ -70,7 +70,7 @@ TEST(LlvmLibcX86LongDoubleTest, is_nan) {
for (unsigned int i = 0; i < COUNT; ++i) {
// If exponent is zero, then the number is a valid but denormal value.
bits.set_mantissa(i);
long double valid = bits.get_val();
long double valid = bits;
ASSERT_EQ(static_cast<int>(isnan(valid)), 0);
ASSERT_FALSE(bits.is_nan());
}
@ -80,7 +80,7 @@ TEST(LlvmLibcX86LongDoubleTest, is_nan) {
for (unsigned int i = 0; i < COUNT; ++i) {
// If exponent is zero, then the number is a valid but denormal value.
bits.set_mantissa(i);
long double valid = bits.get_val();
long double valid = bits;
ASSERT_EQ(static_cast<int>(isnan(valid)), 0);
ASSERT_FALSE(bits.is_nan());
}

1
utils/bazel/llvm-project-overlay/libc/BUILD.bazel
View File

@ -662,6 +662,7 @@ libc_support_library(
libc_support_library(
name = "__support_fputil_fp_bits",
hdrs = ["src/__support/FPUtil/FPBits.h"],
textual_hdrs = ["src/__support/FPUtil/x86_64/LongDoubleBits.h"],
deps = [
":__support_common",
":__support_cpp_bit",

42
utils/bazel/llvm-project-overlay/libc/test/src/__support/FPUtil/BUILD.bazel
View File

@ -1,42 +0,0 @@
# This file is licensed 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
# Tests for LLVM libc __support functions.
load("//libc/test:libc_test_rules.bzl", "libc_test")
package(default_visibility = ["//visibility:public"])
licenses(["notice"])
libc_test(
name = "fpbits_test",
srcs = ["fpbits_test.cpp"],
deps = [
"//libc:__support_fputil_fp_bits",
"//libc:__support_fputil_fpbits_str",
],
)
libc_test(
name = "dyadic_float_test",
srcs = ["dyadic_float_test.cpp"],
deps = [
"//libc:__support_fputil_dyadic_float",
"//libc:__support_uint",
"//libc:__support_uint128",
"//libc/test/UnitTest:fp_test_helpers",
"//libc/utils/MPFRWrapper:mpfr_wrapper",
],
)
libc_test(
name = "rounding_mode_test",
srcs = ["rounding_mode_test.cpp"],
deps = [
"//libc:__support_fputil_rounding_mode",
"//libc:__support_uint128",
"//libc/utils/MPFRWrapper:mpfr_wrapper",
],
)