Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Optimize less-than #264

Merged
merged 1 commit into from
Mar 15, 2022
Merged

Optimize less-than #264

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 8 additions & 5 deletions include/intx/intx.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1087,11 +1087,14 @@ inline constexpr bool operator!=(const T& x, const uint<N>& y) noexcept
#if !defined(_MSC_VER) || _MSC_VER < 1916 // This kills MSVC 2017 compiler.
inline constexpr bool operator<(const uint256& x, const uint256& y) noexcept
{
const auto xhi = uint128{x[2], x[3]};
const auto xlo = uint128{x[0], x[1]};
const auto yhi = uint128{y[2], y[3]};
const auto ylo = uint128{y[0], y[1]};
return (unsigned(xhi < yhi) | (unsigned(xhi == yhi) & unsigned(xlo < ylo))) != 0;
auto xp = intx::uint128{x[2], x[3]};
auto yp = intx::uint128{y[2], y[3]};
if (xp == yp)
{
xp = intx::uint128{x[0], x[1]};
yp = intx::uint128{y[0], y[1]};
}
return xp < yp;
}
#endif

Expand Down
6 changes: 6 additions & 0 deletions test/benchmarks/benchmarks.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -351,6 +351,11 @@ BENCHMARK_TEMPLATE(shift, uint512, uint64_t, shl_public)->DenseRange(-1, 3);
return x < y;
}

[[gnu::noinline]] static bool lt_sub(const uint256& x, const uint256& y) noexcept
{
return subc(x, y).carry;
}

[[gnu::noinline]] static bool lt_wordcmp(const uint256& x, const uint256& y) noexcept
{
for (size_t i = 3; i >= 1; --i)
Expand Down Expand Up @@ -418,6 +423,7 @@ static void compare(benchmark::State& state)
}
}
BENCHMARK_TEMPLATE(compare, lt_public)->DenseRange(64, 256, 64);
BENCHMARK_TEMPLATE(compare, lt_sub)->DenseRange(64, 256, 64);
BENCHMARK_TEMPLATE(compare, lt_wordcmp)->DenseRange(64, 256, 64);
BENCHMARK_TEMPLATE(compare, lt_halves)->DenseRange(64, 256, 64);
#if INTX_HAS_EXTINT
Expand Down