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MathUtilTest: add test for FlushToZero

This commit is contained in:
Tillmann Karras 2014-03-24 03:11:11 +01:00
parent af525266d4
commit e0baed850f
1 changed files with 42 additions and 1 deletions
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43
Source/UnitTests/Common/MathUtilTest.cpp
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@ -4,6 +4,7 @@
#include <gtest/gtest.h>
#include <limits>
#include <random>
#include "Common/MathUtil.h"
@ -29,7 +30,7 @@ TEST(MathUtil, Clamp)
TEST(MathUtil, IsINF)
{
EXPECT_TRUE(MathUtil::IsINF( std::numeric_limits<double>::infinity()));
EXPECT_TRUE(MathUtil::IsINF(+std::numeric_limits<double>::infinity()));
EXPECT_TRUE(MathUtil::IsINF(-std::numeric_limits<double>::infinity()));
}
@ -63,3 +64,43 @@ TEST(MathUtil, Log2)
EXPECT_EQ(3, Log2(15));
EXPECT_EQ(63, Log2(0xFFFFFFFFFFFFFFFFull));
}
TEST(MathUtil, FlushToZero)
{
// To test the software implementation we need to make sure FTZ and DAZ are disabled.
// Using volatile here to ensure the compiler doesn't constant-fold it,
// we want the multiplication to occur at test runtime.
volatile float s = std::numeric_limits<float>::denorm_min();
volatile double d = std::numeric_limits<double>::denorm_min();
EXPECT_LT(0, s * 2);
EXPECT_LT(0, d * 2);
EXPECT_EQ(+0, MathUtil::FlushToZero(+std::numeric_limits<double>::denorm_min()));
EXPECT_EQ(-0, MathUtil::FlushToZero(-std::numeric_limits<double>::denorm_min()));
EXPECT_EQ(+0, MathUtil::FlushToZero(+std::numeric_limits<double>::min() / 2));
EXPECT_EQ(-0, MathUtil::FlushToZero(-std::numeric_limits<double>::min() / 2));
EXPECT_EQ(std::numeric_limits<double>::min(), MathUtil::FlushToZero(std::numeric_limits<double>::min()));
EXPECT_EQ(std::numeric_limits<double>::max(), MathUtil::FlushToZero(std::numeric_limits<double>::max()));
EXPECT_EQ(+std::numeric_limits<double>::infinity(), MathUtil::FlushToZero(+std::numeric_limits<double>::infinity()));
EXPECT_EQ(-std::numeric_limits<double>::infinity(), MathUtil::FlushToZero(-std::numeric_limits<double>::infinity()));
// Test all subnormals as well as an equally large set of random normal floats.
std::default_random_engine engine(0);
std::uniform_int_distribution<u32> dist(0x00800000u, 0x7fffffffu);
for (u32 i = 0; i <= 0x007fffffu; ++i)
{
MathUtil::IntFloat x(i);
EXPECT_EQ(+0, MathUtil::FlushToZero(x.f));
x.i = i | 0x80000000u;
EXPECT_EQ(-0, MathUtil::FlushToZero(x.f));
x.i = dist(engine);
MathUtil::IntFloat y(MathUtil::FlushToZero(x.f));
EXPECT_EQ(x.i, y.i);
x.i |= 0x80000000u;
y.f = MathUtil::FlushToZero(x.f);
EXPECT_EQ(x.i, y.i);
}
}