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Fix ULP matcher #2152

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Fix ULP matcher #2152

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b38cb9b
Allow colored output even while not in a terminal
yyny Jan 13, 2021
0dea387
Add more thorough ULP comparison tests
yyny Jan 13, 2021
e7ae127
Fix ULP matcher
yyny Jan 13, 2021
c793ea3
Add ULP tests for +/- INFINITY
yyny Jan 13, 2021
6dee860
Remove unused include
yyny Jan 13, 2021
70bfb2b
Fix typo
yyny Jan 13, 2021
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11 changes: 10 additions & 1 deletion CMakeLists.txt
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Expand Up @@ -9,6 +9,7 @@ endif()
option(CATCH_INSTALL_DOCS "Install documentation alongside library" ON)
option(CATCH_INSTALL_EXTRAS "Install extras alongside library" ON)
option(CATCH_DEVELOPMENT_BUILD "Build tests, enable warnings, enable Werror, etc" OFF)
option(CATCH_FORCE_COLORED_OUTPUT "Always produce ANSI-colored output (GNU/Clang only)" OFF)

include(CMakeDependentOption)
cmake_dependent_option(CATCH_BUILD_TESTING "Build the SelfTest project" ON "CATCH_DEVELOPMENT_BUILD" OFF)
Expand All @@ -33,6 +34,14 @@ endif()

project(Catch2 LANGUAGES CXX VERSION 3.0.0)

if (${CATCH_FORCE_COLORED_OUTPUT})
if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
add_compile_options (-fdiagnostics-color=always)
elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
add_compile_options (-fcolor-diagnostics)
endif ()
endif()

# Provide path for scripts
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/CMake")
include(GNUInstallDirs)
Expand Down Expand Up @@ -158,7 +167,7 @@ if (NOT_SUBPROJECT)
DESTINATION
${CATCH_CMAKE_CONFIG_DESTINATION}
)

# Install debugger helpers
install(
FILES
Expand Down
61 changes: 50 additions & 11 deletions src/catch2/matchers/catch_matchers_floating_point.cpp
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Expand Up @@ -38,23 +38,62 @@ namespace {
return i;
}

// Calculates the ULP distance between two floating point numbers
// That is, the number of valid IEEE-754 floating point representations
// between the two values. In the general case we can say:
// * if nextafter(a, INFINITY) == b, then ulpDistance(a, b) == 1
// * if a == nextafter(b, INFINITY), then ulpDistance(a, b) == -1
// however, as an exception, the distance between positive and negative
// zero is considered to always have a value of zero
// There is an argument to be made that this distance should be one, since
// nextafter(-0f, INFINITY) == +0f
// nextafter(+0f, -INFINITY) == -0f
// However, the above exception was chosen to ensure that a == b implies
// ulpDistance(a, b) == 0
// and that
// ulpDistance(-x, x) == ulpDistance(0, x)*2
// Denormalized normals are counted normally in distance calculations.
// See also: boost/math/special_functions/next.hpp
template <typename FP>
int64_t ulpDistance(FP a, FP b) {
// Smallest value greater than zero
constexpr FP EPSILON_0 = std::numeric_limits<FP>::denorm_min();
// Largest possible distance we can return
constexpr int64_t INFINITE_DISTANCE = std::numeric_limits<int64_t>::max();
if (Catch::isnan(a) || Catch::isnan(b)) // Early out for NaNs
return INFINITE_DISTANCE;
if (!std::isfinite(a) || !std::isfinite(b)) // Early out for infinity
return INFINITE_DISTANCE;
if(a > b) // Ensure a < b
return -ulpDistance(b, a);
if(a == b) // This also ensures ulpDistance(-0f, +0f) == 0
return 0;
if(a == 0) // Ensure a != 0
return 1 + std::abs(ulpDistance((b < 0) ? -EPSILON_0 : EPSILON_0, b));
if(b == 0) // Ensure b != 0
return 1 + std::abs(ulpDistance((a < 0) ? -EPSILON_0 : EPSILON_0, a));
if((a < 0) != (b < 0)) // Ensure a and b have the same sign
return 2 + std::abs(ulpDistance((b < 0) ? -EPSILON_0 : EPSILON_0, b))
+ std::abs(ulpDistance((a < 0) ? -EPSILON_0 : EPSILON_0, a));
if(a < 0) // Ensure a and b are positive
return ulpDistance(-b, -a);
assert(a >= 0);
assert(a < b);
int64_t ac = convert(a);
int64_t bc = convert(b);
return bc - ac; // ULP distance, assuming IEEE-754 floating point numbers
}

template <typename FP>
bool almostEqualUlps(FP lhs, FP rhs, uint64_t maxUlpDiff) {
// Comparison with NaN should always be false.
// This way we can rule it out before getting into the ugly details
if (Catch::isnan(lhs) || Catch::isnan(rhs)) {
if (Catch::isnan(lhs) || Catch::isnan(rhs))
return false;
}

auto lc = convert(lhs);
auto rc = convert(rhs);

if ((lc < 0) != (rc < 0)) {
// Potentially we can have +0 and -0
if (!std::isfinite(lhs) || !std::isfinite(rhs))
return lhs == rhs;
}

auto ulpDiff = std::abs(lc - rc);
auto ulpDiff = std::abs(ulpDistance(lhs, rhs));
return static_cast<uint64_t>(ulpDiff) <= maxUlpDiff;
}

Expand Down Expand Up @@ -128,7 +167,7 @@ namespace Detail {
WithinUlpsMatcher::WithinUlpsMatcher(double target, uint64_t ulps, Detail::FloatingPointKind baseType)
:m_target{ target }, m_ulps{ ulps }, m_type{ baseType } {
CATCH_ENFORCE(m_type == Detail::FloatingPointKind::Double
|| m_ulps < (std::numeric_limits<uint32_t>::max)(),
|| m_ulps <= (std::numeric_limits<uint32_t>::max)(),
"Provided ULP is impossibly large for a float comparison.");
}

Expand Down
92 changes: 80 additions & 12 deletions tests/SelfTest/UsageTests/Matchers.tests.cpp
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Expand Up @@ -447,15 +447,45 @@ namespace { namespace MatchersTests {
REQUIRE_THAT(-10.f, WithinAbs(-9.6f, 0.5f));
}
SECTION("ULPs") {
REQUIRE_THAT(1.f, WithinULP(1.f, 0));

REQUIRE_THAT(nextafter(1.f, 2.f), WithinULP(1.f, 1));
REQUIRE_THAT(0.f, WithinULP(nextafter(0.f, 1.f), 1));
REQUIRE_THAT(1.f, WithinULP(nextafter(1.f, 0.f), 1));
REQUIRE_THAT(1.f, !WithinULP(nextafter(1.f, 2.f), 0));
const float ONE_EPSILON_0 = nextafter(0.f, 1.f);
const float TWO_EPSILON_0 = nextafter(ONE_EPSILON_0, 1.f);
const float NEG_ONE_EPSILON_1 = nextafter(1.f, 0.f);
const float POS_ONE_EPSILON_1 = nextafter(1.f, 2.f);
const uint32_t ULP_DISTANCE_0_1 = 1065353216;

REQUIRE_THAT(1.f, WithinULP(1.f, 0));
REQUIRE_THAT(-1.f, WithinULP(-1.f, 0));
REQUIRE_THAT(-1.f, !WithinULP(1.f, 0));
REQUIRE_THAT(1.f, !WithinULP(-1.f, 0));
REQUIRE_THAT(-0.f, WithinULP(0.f, 0));
REQUIRE_THAT(0.f, WithinULP(-0.f, 0));
REQUIRE_THAT(999e10f, WithinULP(999e10f, 0));
REQUIRE_THAT(-999e10f, WithinULP(-999e10f, 0));
REQUIRE_THAT(999e10f, !WithinULP(-999e10f, 0));
REQUIRE_THAT(-999e10f, !WithinULP(999e10f, 0));
REQUIRE_THAT(0.f, !WithinULP(1.f, 1));
REQUIRE_THAT(1.f, !WithinULP(0.f, 1));

REQUIRE_THAT(0.f, WithinULP(ONE_EPSILON_0, 1));
REQUIRE_THAT(-ONE_EPSILON_0, WithinULP(ONE_EPSILON_0, 2));
REQUIRE_THAT(0.f, WithinULP(1.f, ULP_DISTANCE_0_1));
REQUIRE_THAT(0.f, WithinULP(-1.f, ULP_DISTANCE_0_1));
REQUIRE_THAT(1.f, WithinULP(0.f, ULP_DISTANCE_0_1));
REQUIRE_THAT(-1.f, WithinULP(0.f, ULP_DISTANCE_0_1));
REQUIRE_THAT(-1.f, WithinULP(1.f, 2*ULP_DISTANCE_0_1));
REQUIRE_THAT(1.f, WithinULP(-1.f, 2*ULP_DISTANCE_0_1));

REQUIRE_THAT(0.f, WithinULP(ONE_EPSILON_0, 1));
REQUIRE_THAT(0.f, WithinULP(TWO_EPSILON_0, 2));
REQUIRE_THAT(1.f, WithinULP(NEG_ONE_EPSILON_1, 1));
REQUIRE_THAT(1.f, WithinULP(POS_ONE_EPSILON_1, 1));
REQUIRE_THAT(POS_ONE_EPSILON_1, WithinULP(1.f, 1));
REQUIRE_THAT(1.f, !WithinULP(NEG_ONE_EPSILON_1, 0));
REQUIRE_THAT(1.f, !WithinULP(POS_ONE_EPSILON_1, 0));

REQUIRE_THAT(0.f, WithinULP(TWO_EPSILON_0, 2));
REQUIRE_THAT(ONE_EPSILON_0, WithinULP(TWO_EPSILON_0, 1));
REQUIRE_THAT(POS_ONE_EPSILON_1, WithinULP(NEG_ONE_EPSILON_1, 2));
}
SECTION("Composed") {
REQUIRE_THAT(1.f, WithinAbs(1.f, 0.5) || WithinULP(1.f, 1));
Expand Down Expand Up @@ -503,15 +533,45 @@ namespace { namespace MatchersTests {
REQUIRE_THAT(-10., WithinAbs(-9.6, 0.5));
}
SECTION("ULPs") {
REQUIRE_THAT(1., WithinULP(1., 0));

REQUIRE_THAT(nextafter(1., 2.), WithinULP(1., 1));
REQUIRE_THAT(0., WithinULP(nextafter(0., 1.), 1));
REQUIRE_THAT(1., WithinULP(nextafter(1., 0.), 1));
REQUIRE_THAT(1., !WithinULP(nextafter(1., 2.), 0));
const double ONE_EPSILON_0 = nextafter(0., 1.);
const double TWO_EPSILON_0 = nextafter(ONE_EPSILON_0, 1.);
const double NEG_ONE_EPSILON_1 = nextafter(1., 0.);
const double POS_ONE_EPSILON_1 = nextafter(1., 2.);
const uint64_t ULP_DISTANCE_0_1 = 4607182418800017408;

REQUIRE_THAT(1., WithinULP(1., 0));
REQUIRE_THAT(-1., WithinULP(-1., 0));
REQUIRE_THAT(-1., !WithinULP(1., 0));
REQUIRE_THAT(1., !WithinULP(-1., 0));
REQUIRE_THAT(-0., WithinULP(0., 0));
REQUIRE_THAT(0., WithinULP(-0., 0));
REQUIRE_THAT(999e10, WithinULP(999e10, 0));
REQUIRE_THAT(-999e10, WithinULP(-999e10, 0));
REQUIRE_THAT(999e10, !WithinULP(-999e10, 0));
REQUIRE_THAT(-999e10, !WithinULP(999e10, 0));
REQUIRE_THAT(0., !WithinULP(1., 1));
REQUIRE_THAT(1., !WithinULP(0., 1));

REQUIRE_THAT(0., WithinULP(ONE_EPSILON_0, 1));
REQUIRE_THAT(-ONE_EPSILON_0, WithinULP(ONE_EPSILON_0, 2));
REQUIRE_THAT(0., WithinULP(1., ULP_DISTANCE_0_1));
REQUIRE_THAT(0., WithinULP(-1., ULP_DISTANCE_0_1));
REQUIRE_THAT(1., WithinULP(0., ULP_DISTANCE_0_1));
REQUIRE_THAT(-1., WithinULP(0., ULP_DISTANCE_0_1));
REQUIRE_THAT(-1., WithinULP(1., 2*ULP_DISTANCE_0_1));
REQUIRE_THAT(1., WithinULP(-1., 2*ULP_DISTANCE_0_1));

REQUIRE_THAT(0., WithinULP(ONE_EPSILON_0, 1));
REQUIRE_THAT(0., WithinULP(TWO_EPSILON_0, 2));
REQUIRE_THAT(1., WithinULP(NEG_ONE_EPSILON_1, 1));
REQUIRE_THAT(1., WithinULP(POS_ONE_EPSILON_1, 1));
REQUIRE_THAT(POS_ONE_EPSILON_1, WithinULP(1., 1));
REQUIRE_THAT(1., !WithinULP(NEG_ONE_EPSILON_1, 0));
REQUIRE_THAT(1., !WithinULP(POS_ONE_EPSILON_1, 0));

REQUIRE_THAT(0., WithinULP(TWO_EPSILON_0, 2));
REQUIRE_THAT(ONE_EPSILON_0, WithinULP(TWO_EPSILON_0, 1));
REQUIRE_THAT(POS_ONE_EPSILON_1, WithinULP(NEG_ONE_EPSILON_1, 2));
}
SECTION("Composed") {
REQUIRE_THAT(1., WithinAbs(1., 0.5) || WithinULP(2., 1));
Expand Down Expand Up @@ -541,6 +601,14 @@ namespace { namespace MatchersTests {
REQUIRE_THAT(NAN, !WithinRel(NAN));
REQUIRE_THAT(1., !WithinRel(NAN));
REQUIRE_THAT(NAN, !WithinRel(1.));
REQUIRE_THAT(INFINITY, WithinULP(INFINITY, 0));
REQUIRE_THAT(-INFINITY, WithinULP(-INFINITY, 0));
REQUIRE_THAT(INFINITY, !WithinULP(-INFINITY, 0));
REQUIRE_THAT(-INFINITY, !WithinULP(INFINITY, 0));
REQUIRE_THAT(-INFINITY, !WithinULP(static_cast<float>(INFINITY), std::numeric_limits<uint32_t>::max()));
REQUIRE_THAT(INFINITY, !WithinULP(static_cast<float>(-INFINITY), std::numeric_limits<uint32_t>::max()));
REQUIRE_THAT(1., !WithinULP(INFINITY, std::numeric_limits<uint32_t>::max()));
REQUIRE_THAT(1., !WithinULP(-INFINITY, std::numeric_limits<uint32_t>::max()));
}

TEST_CASE("Arbitrary predicate matcher", "[matchers][generic]") {
Expand Down