tvl-depot/absl/numeric/int128.cc
Abseil Team 37dd2562ec Export of internal Abseil changes
--
8bdb2020150ed0fd4a4e520e454dc5f54e33f776 by Eric Fiselier <ericwf@google.com>:

Workaround bug in GCC 9.2 and after.

PiperOrigin-RevId: 291982551

--
47ff4820e595f96c082a90d733725f6882d83e3b by Abseil Team <absl-team@google.com>:

Improve ABSL_ATTRIBUTE_PACKED documentation

Recommend to apply ABSL_ATTRIBUTE_PACKED to structure members instead of to an entire structure because applying this attribute to an entire structure may cause the compiler to generate suboptimal code. It reduces the alignment of the data structure from a value larger than one to one. When applied to a structure, ABSL_ATTRIBUTE_PACKED reduces the alignment of a structure (alignof()) to 1. As a result, the compiler can no longer assume that e.g. uint32 members are aligned on a four byte boundary and hence is forced to use single-byte load and store instructions on CPU architectures that do not support non-aligned loads or stores.

PiperOrigin-RevId: 291977920

--
902b7a86f860da699d3a2e5c738be5ef73ede3b4 by Mark Barolak <mbar@google.com>:

Internal change

PiperOrigin-RevId: 291963048

--
bb3bd3247e376d53a3080b105f13ec7566d3ae50 by Abseil Team <absl-team@google.com>:

Support the C++17 insert_or_assign() API in btree_map.

PiperOrigin-RevId: 291945474

--
ff3b3cfcbbc64f086f95501f48d49426bcde356f by Gennadiy Rozental <rogeeff@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 291861110

--
fd465cd9cbbacd3962f67a7346d6462edaddd809 by Derek Mauro <dmauro@google.com>:

Add flaky=1 to beta_distribution_test.

PiperOrigin-RevId: 291757364

--
3603adfb59c4128c542b670952cce250d59e1f67 by Derek Mauro <dmauro@google.com>:

Separate the initialization of NumCPUs() and NominalCPUFrequency()

The OSS version of Abseil never needs to call NominalCPUFrequency().
In some configurations, initializing NominalCPUFrequency() requires
spending at least 3ms measuring the CPU frequency. By separating the
initialization from NumCPUs(), which is called in most configurations,
we can save at least 3ms of program startup time.

PiperOrigin-RevId: 291737273

--
bea9e4a6bff5a0351d340deab966641867e08c4d by Abseil Team <absl-team@google.com>:

Change the cmake library names not to have a redundant `absl_` prefix.

PiperOrigin-RevId: 291640501

--
501b602ef260cd7c8c527342581ceffb3c5b6d4c by Gennadiy Rozental <rogeeff@google.com>:

Introducing benchmark for absl::GetFlag.

PiperOrigin-RevId: 291433394

--
4eeaddc788da4b91c272a8adca77ca6dbbbc1d44 by Xiaoyi Zhang <zhangxy@google.com>:

fix: Add support for more ARM processors detection

Import of https://github.com/abseil/abseil-cpp/pull/608

PiperOrigin-RevId: 291420397

--
a3087a8e883c5d71de7d9bd4ec8f4db5142dfcf5 by Derek Mauro <dmauro@google.com>:

Removes the flaky raw_hash_set prefetch test

PiperOrigin-RevId: 291197079

--
aad6c2121c102ac36216e771c83227cf3e3bfd66 by Andy Soffer <asoffer@google.com>:

Enable building Abseil as a DLL.
This is currently experimental and unsupported.

This CL does a few things:
1. Adds the ABSL_DLL macro to any class holding a static data member, or to global constants in headers.
2. Adds a whitelist of all files in the DLL and all the build targets that are conglomerated into the DLL.
3. When BUILD_SHARED_LIBS is specified, any build target that would be in the DLL still exists, but we swap out all of it's dependencies so it just depends on abseil_dll

PiperOrigin-RevId: 291192055

--
5e888cd6f2a7722805d41f872108a03a84e421c7 by Mark Barolak <mbar@google.com>:

Move absl/strings/internal/escaping.{cc,h} into internal build targets.

This puts absl/strings/internal/escaping.h behind a whitelist and it also resolves https://github.com/abseil/abseil-cpp/issues/604.

PiperOrigin-RevId: 291173320

--
166836d24970da87587c1728036f53f05a28f0af by Eric Fiselier <ericwf@google.com>:

Internal Change.

PiperOrigin-RevId: 291012718

--
996ddb3dffda02440fa93f30ca5d71b14b688875 by Abseil Team <absl-team@google.com>:

Fix shared libraries log spam for built-in types in absl::GetFlag

PiperOrigin-RevId: 290772743
GitOrigin-RevId: 8bdb2020150ed0fd4a4e520e454dc5f54e33f776
Change-Id: I8bf2265dd14ebbace220a1b6b982bb5040ad2a26
2020-01-28 16:07:41 -05:00

404 lines
14 KiB
C++

// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/numeric/int128.h"
#include <stddef.h>
#include <cassert>
#include <iomanip>
#include <ostream> // NOLINT(readability/streams)
#include <sstream>
#include <string>
#include <type_traits>
namespace absl {
ABSL_NAMESPACE_BEGIN
ABSL_DLL const uint128 kuint128max = MakeUint128(
std::numeric_limits<uint64_t>::max(), std::numeric_limits<uint64_t>::max());
namespace {
// Returns the 0-based position of the last set bit (i.e., most significant bit)
// in the given uint64_t. The argument may not be 0.
//
// For example:
// Given: 5 (decimal) == 101 (binary)
// Returns: 2
#define STEP(T, n, pos, sh) \
do { \
if ((n) >= (static_cast<T>(1) << (sh))) { \
(n) = (n) >> (sh); \
(pos) |= (sh); \
} \
} while (0)
static inline int Fls64(uint64_t n) {
assert(n != 0);
int pos = 0;
STEP(uint64_t, n, pos, 0x20);
uint32_t n32 = static_cast<uint32_t>(n);
STEP(uint32_t, n32, pos, 0x10);
STEP(uint32_t, n32, pos, 0x08);
STEP(uint32_t, n32, pos, 0x04);
return pos + ((uint64_t{0x3333333322221100} >> (n32 << 2)) & 0x3);
}
#undef STEP
// Like Fls64() above, but returns the 0-based position of the last set bit
// (i.e., most significant bit) in the given uint128. The argument may not be 0.
static inline int Fls128(uint128 n) {
if (uint64_t hi = Uint128High64(n)) {
return Fls64(hi) + 64;
}
return Fls64(Uint128Low64(n));
}
// Long division/modulo for uint128 implemented using the shift-subtract
// division algorithm adapted from:
// https://stackoverflow.com/questions/5386377/division-without-using
void DivModImpl(uint128 dividend, uint128 divisor, uint128* quotient_ret,
uint128* remainder_ret) {
assert(divisor != 0);
if (divisor > dividend) {
*quotient_ret = 0;
*remainder_ret = dividend;
return;
}
if (divisor == dividend) {
*quotient_ret = 1;
*remainder_ret = 0;
return;
}
uint128 denominator = divisor;
uint128 quotient = 0;
// Left aligns the MSB of the denominator and the dividend.
const int shift = Fls128(dividend) - Fls128(denominator);
denominator <<= shift;
// Uses shift-subtract algorithm to divide dividend by denominator. The
// remainder will be left in dividend.
for (int i = 0; i <= shift; ++i) {
quotient <<= 1;
if (dividend >= denominator) {
dividend -= denominator;
quotient |= 1;
}
denominator >>= 1;
}
*quotient_ret = quotient;
*remainder_ret = dividend;
}
template <typename T>
uint128 MakeUint128FromFloat(T v) {
static_assert(std::is_floating_point<T>::value, "");
// Rounding behavior is towards zero, same as for built-in types.
// Undefined behavior if v is NaN or cannot fit into uint128.
assert(std::isfinite(v) && v > -1 &&
(std::numeric_limits<T>::max_exponent <= 128 ||
v < std::ldexp(static_cast<T>(1), 128)));
if (v >= std::ldexp(static_cast<T>(1), 64)) {
uint64_t hi = static_cast<uint64_t>(std::ldexp(v, -64));
uint64_t lo = static_cast<uint64_t>(v - std::ldexp(static_cast<T>(hi), 64));
return MakeUint128(hi, lo);
}
return MakeUint128(0, static_cast<uint64_t>(v));
}
#if defined(__clang__) && !defined(__SSE3__)
// Workaround for clang bug: https://bugs.llvm.org/show_bug.cgi?id=38289
// Casting from long double to uint64_t is miscompiled and drops bits.
// It is more work, so only use when we need the workaround.
uint128 MakeUint128FromFloat(long double v) {
// Go 50 bits at a time, that fits in a double
static_assert(std::numeric_limits<double>::digits >= 50, "");
static_assert(std::numeric_limits<long double>::digits <= 150, "");
// Undefined behavior if v is not finite or cannot fit into uint128.
assert(std::isfinite(v) && v > -1 && v < std::ldexp(1.0L, 128));
v = std::ldexp(v, -100);
uint64_t w0 = static_cast<uint64_t>(static_cast<double>(std::trunc(v)));
v = std::ldexp(v - static_cast<double>(w0), 50);
uint64_t w1 = static_cast<uint64_t>(static_cast<double>(std::trunc(v)));
v = std::ldexp(v - static_cast<double>(w1), 50);
uint64_t w2 = static_cast<uint64_t>(static_cast<double>(std::trunc(v)));
return (static_cast<uint128>(w0) << 100) | (static_cast<uint128>(w1) << 50) |
static_cast<uint128>(w2);
}
#endif // __clang__ && !__SSE3__
} // namespace
uint128::uint128(float v) : uint128(MakeUint128FromFloat(v)) {}
uint128::uint128(double v) : uint128(MakeUint128FromFloat(v)) {}
uint128::uint128(long double v) : uint128(MakeUint128FromFloat(v)) {}
uint128 operator/(uint128 lhs, uint128 rhs) {
#if defined(ABSL_HAVE_INTRINSIC_INT128)
return static_cast<unsigned __int128>(lhs) /
static_cast<unsigned __int128>(rhs);
#else // ABSL_HAVE_INTRINSIC_INT128
uint128 quotient = 0;
uint128 remainder = 0;
DivModImpl(lhs, rhs, &quotient, &remainder);
return quotient;
#endif // ABSL_HAVE_INTRINSIC_INT128
}
uint128 operator%(uint128 lhs, uint128 rhs) {
#if defined(ABSL_HAVE_INTRINSIC_INT128)
return static_cast<unsigned __int128>(lhs) %
static_cast<unsigned __int128>(rhs);
#else // ABSL_HAVE_INTRINSIC_INT128
uint128 quotient = 0;
uint128 remainder = 0;
DivModImpl(lhs, rhs, &quotient, &remainder);
return remainder;
#endif // ABSL_HAVE_INTRINSIC_INT128
}
namespace {
std::string Uint128ToFormattedString(uint128 v, std::ios_base::fmtflags flags) {
// Select a divisor which is the largest power of the base < 2^64.
uint128 div;
int div_base_log;
switch (flags & std::ios::basefield) {
case std::ios::hex:
div = 0x1000000000000000; // 16^15
div_base_log = 15;
break;
case std::ios::oct:
div = 01000000000000000000000; // 8^21
div_base_log = 21;
break;
default: // std::ios::dec
div = 10000000000000000000u; // 10^19
div_base_log = 19;
break;
}
// Now piece together the uint128 representation from three chunks of the
// original value, each less than "div" and therefore representable as a
// uint64_t.
std::ostringstream os;
std::ios_base::fmtflags copy_mask =
std::ios::basefield | std::ios::showbase | std::ios::uppercase;
os.setf(flags & copy_mask, copy_mask);
uint128 high = v;
uint128 low;
DivModImpl(high, div, &high, &low);
uint128 mid;
DivModImpl(high, div, &high, &mid);
if (Uint128Low64(high) != 0) {
os << Uint128Low64(high);
os << std::noshowbase << std::setfill('0') << std::setw(div_base_log);
os << Uint128Low64(mid);
os << std::setw(div_base_log);
} else if (Uint128Low64(mid) != 0) {
os << Uint128Low64(mid);
os << std::noshowbase << std::setfill('0') << std::setw(div_base_log);
}
os << Uint128Low64(low);
return os.str();
}
} // namespace
std::ostream& operator<<(std::ostream& os, uint128 v) {
std::ios_base::fmtflags flags = os.flags();
std::string rep = Uint128ToFormattedString(v, flags);
// Add the requisite padding.
std::streamsize width = os.width(0);
if (static_cast<size_t>(width) > rep.size()) {
std::ios::fmtflags adjustfield = flags & std::ios::adjustfield;
if (adjustfield == std::ios::left) {
rep.append(width - rep.size(), os.fill());
} else if (adjustfield == std::ios::internal &&
(flags & std::ios::showbase) &&
(flags & std::ios::basefield) == std::ios::hex && v != 0) {
rep.insert(2, width - rep.size(), os.fill());
} else {
rep.insert(0, width - rep.size(), os.fill());
}
}
return os << rep;
}
namespace {
uint128 UnsignedAbsoluteValue(int128 v) {
// Cast to uint128 before possibly negating because -Int128Min() is undefined.
return Int128High64(v) < 0 ? -uint128(v) : uint128(v);
}
} // namespace
#if !defined(ABSL_HAVE_INTRINSIC_INT128)
namespace {
template <typename T>
int128 MakeInt128FromFloat(T v) {
// Conversion when v is NaN or cannot fit into int128 would be undefined
// behavior if using an intrinsic 128-bit integer.
assert(std::isfinite(v) && (std::numeric_limits<T>::max_exponent <= 127 ||
(v >= -std::ldexp(static_cast<T>(1), 127) &&
v < std::ldexp(static_cast<T>(1), 127))));
// We must convert the absolute value and then negate as needed, because
// floating point types are typically sign-magnitude. Otherwise, the
// difference between the high and low 64 bits when interpreted as two's
// complement overwhelms the precision of the mantissa.
uint128 result = v < 0 ? -MakeUint128FromFloat(-v) : MakeUint128FromFloat(v);
return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(result)),
Uint128Low64(result));
}
} // namespace
int128::int128(float v) : int128(MakeInt128FromFloat(v)) {}
int128::int128(double v) : int128(MakeInt128FromFloat(v)) {}
int128::int128(long double v) : int128(MakeInt128FromFloat(v)) {}
int128 operator/(int128 lhs, int128 rhs) {
assert(lhs != Int128Min() || rhs != -1); // UB on two's complement.
uint128 quotient = 0;
uint128 remainder = 0;
DivModImpl(UnsignedAbsoluteValue(lhs), UnsignedAbsoluteValue(rhs),
&quotient, &remainder);
if ((Int128High64(lhs) < 0) != (Int128High64(rhs) < 0)) quotient = -quotient;
return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(quotient)),
Uint128Low64(quotient));
}
int128 operator%(int128 lhs, int128 rhs) {
assert(lhs != Int128Min() || rhs != -1); // UB on two's complement.
uint128 quotient = 0;
uint128 remainder = 0;
DivModImpl(UnsignedAbsoluteValue(lhs), UnsignedAbsoluteValue(rhs),
&quotient, &remainder);
if (Int128High64(lhs) < 0) remainder = -remainder;
return MakeInt128(int128_internal::BitCastToSigned(Uint128High64(remainder)),
Uint128Low64(remainder));
}
#endif // ABSL_HAVE_INTRINSIC_INT128
std::ostream& operator<<(std::ostream& os, int128 v) {
std::ios_base::fmtflags flags = os.flags();
std::string rep;
// Add the sign if needed.
bool print_as_decimal =
(flags & std::ios::basefield) == std::ios::dec ||
(flags & std::ios::basefield) == std::ios_base::fmtflags();
if (print_as_decimal) {
if (Int128High64(v) < 0) {
rep = "-";
} else if (flags & std::ios::showpos) {
rep = "+";
}
}
rep.append(Uint128ToFormattedString(
print_as_decimal ? UnsignedAbsoluteValue(v) : uint128(v), os.flags()));
// Add the requisite padding.
std::streamsize width = os.width(0);
if (static_cast<size_t>(width) > rep.size()) {
switch (flags & std::ios::adjustfield) {
case std::ios::left:
rep.append(width - rep.size(), os.fill());
break;
case std::ios::internal:
if (print_as_decimal && (rep[0] == '+' || rep[0] == '-')) {
rep.insert(1, width - rep.size(), os.fill());
} else if ((flags & std::ios::basefield) == std::ios::hex &&
(flags & std::ios::showbase) && v != 0) {
rep.insert(2, width - rep.size(), os.fill());
} else {
rep.insert(0, width - rep.size(), os.fill());
}
break;
default: // std::ios::right
rep.insert(0, width - rep.size(), os.fill());
break;
}
}
return os << rep;
}
ABSL_NAMESPACE_END
} // namespace absl
namespace std {
constexpr bool numeric_limits<absl::uint128>::is_specialized;
constexpr bool numeric_limits<absl::uint128>::is_signed;
constexpr bool numeric_limits<absl::uint128>::is_integer;
constexpr bool numeric_limits<absl::uint128>::is_exact;
constexpr bool numeric_limits<absl::uint128>::has_infinity;
constexpr bool numeric_limits<absl::uint128>::has_quiet_NaN;
constexpr bool numeric_limits<absl::uint128>::has_signaling_NaN;
constexpr float_denorm_style numeric_limits<absl::uint128>::has_denorm;
constexpr bool numeric_limits<absl::uint128>::has_denorm_loss;
constexpr float_round_style numeric_limits<absl::uint128>::round_style;
constexpr bool numeric_limits<absl::uint128>::is_iec559;
constexpr bool numeric_limits<absl::uint128>::is_bounded;
constexpr bool numeric_limits<absl::uint128>::is_modulo;
constexpr int numeric_limits<absl::uint128>::digits;
constexpr int numeric_limits<absl::uint128>::digits10;
constexpr int numeric_limits<absl::uint128>::max_digits10;
constexpr int numeric_limits<absl::uint128>::radix;
constexpr int numeric_limits<absl::uint128>::min_exponent;
constexpr int numeric_limits<absl::uint128>::min_exponent10;
constexpr int numeric_limits<absl::uint128>::max_exponent;
constexpr int numeric_limits<absl::uint128>::max_exponent10;
constexpr bool numeric_limits<absl::uint128>::traps;
constexpr bool numeric_limits<absl::uint128>::tinyness_before;
constexpr bool numeric_limits<absl::int128>::is_specialized;
constexpr bool numeric_limits<absl::int128>::is_signed;
constexpr bool numeric_limits<absl::int128>::is_integer;
constexpr bool numeric_limits<absl::int128>::is_exact;
constexpr bool numeric_limits<absl::int128>::has_infinity;
constexpr bool numeric_limits<absl::int128>::has_quiet_NaN;
constexpr bool numeric_limits<absl::int128>::has_signaling_NaN;
constexpr float_denorm_style numeric_limits<absl::int128>::has_denorm;
constexpr bool numeric_limits<absl::int128>::has_denorm_loss;
constexpr float_round_style numeric_limits<absl::int128>::round_style;
constexpr bool numeric_limits<absl::int128>::is_iec559;
constexpr bool numeric_limits<absl::int128>::is_bounded;
constexpr bool numeric_limits<absl::int128>::is_modulo;
constexpr int numeric_limits<absl::int128>::digits;
constexpr int numeric_limits<absl::int128>::digits10;
constexpr int numeric_limits<absl::int128>::max_digits10;
constexpr int numeric_limits<absl::int128>::radix;
constexpr int numeric_limits<absl::int128>::min_exponent;
constexpr int numeric_limits<absl::int128>::min_exponent10;
constexpr int numeric_limits<absl::int128>::max_exponent;
constexpr int numeric_limits<absl::int128>::max_exponent10;
constexpr bool numeric_limits<absl::int128>::traps;
constexpr bool numeric_limits<absl::int128>::tinyness_before;
} // namespace std