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FloatUtils: Remove IntDouble and IntFloat

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Type punning via unions in C++ invokes undefined behavior. Instead, leverage BitCast,
our variant of C++2a's std::bit_cast
This commit is contained in:
Lioncash 2018-05-10 10:35:00 -04:00
parent bde4e970f1
commit 0a3631cc76
No known key found for this signature in database
GPG Key ID: 4E3C3CC1031BA9C7
3 changed files with 32 additions and 46 deletions
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46
Source/Core/Common/FloatUtils.h
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@ -7,6 +7,7 @@
#include <array>
#include <limits>
#include "Common/BitUtils.h"
#include "Common/CommonTypes.h"
namespace Common
@ -55,54 +56,39 @@ enum : u32
FLOAT_ZERO = 0x00000000
};
union IntDouble
{
double d;
u64 i;
explicit IntDouble(u64 _i) : i(_i) {}
explicit IntDouble(double _d) : d(_d) {}
};
union IntFloat
{
float f;
u32 i;
explicit IntFloat(u32 _i) : i(_i) {}
explicit IntFloat(float _f) : f(_f) {}
};
inline bool IsQNAN(double d)
{
IntDouble x(d);
return ((x.i & DOUBLE_EXP) == DOUBLE_EXP) && ((x.i & DOUBLE_QBIT) == DOUBLE_QBIT);
const u64 i = BitCast<u64>(d);
return ((i & DOUBLE_EXP) == DOUBLE_EXP) && ((i & DOUBLE_QBIT) == DOUBLE_QBIT);
}
inline bool IsSNAN(double d)
{
IntDouble x(d);
return ((x.i & DOUBLE_EXP) == DOUBLE_EXP) && ((x.i & DOUBLE_FRAC) != DOUBLE_ZERO) &&
((x.i & DOUBLE_QBIT) == DOUBLE_ZERO);
const u64 i = BitCast<u64>(d);
return ((i & DOUBLE_EXP) == DOUBLE_EXP) && ((i & DOUBLE_FRAC) != DOUBLE_ZERO) &&
((i & DOUBLE_QBIT) == DOUBLE_ZERO);
}
inline float FlushToZero(float f)
{
IntFloat x(f);
if ((x.i & FLOAT_EXP) == 0)
u32 i = BitCast<u32>(f);
if ((i & FLOAT_EXP) == 0)
{
x.i &= FLOAT_SIGN; // turn into signed zero
// Turn into signed zero
i &= FLOAT_SIGN;
}
return x.f;
return BitCast<float>(i);
}
inline double FlushToZero(double d)
{
IntDouble x(d);
if ((x.i & DOUBLE_EXP) == 0)
u64 i = BitCast<u64>(d);
if ((i & DOUBLE_EXP) == 0)
{
x.i &= DOUBLE_SIGN; // turn into signed zero
// Turn into signed zero
i &= DOUBLE_SIGN;
}
return x.d;
return BitCast<double>(i);
}
enum PPCFpClass

19
Source/UnitTests/Common/FloatUtilsTest.cpp
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@ -7,6 +7,7 @@
#include <gtest/gtest.h>
#include "Common/BitUtils.h"
#include "Common/FloatUtils.h"
TEST(FloatUtils, IsQNAN)
@ -51,18 +52,16 @@ TEST(FloatUtils, FlushToZero)
std::uniform_int_distribution<u32> dist(0x00800000u, 0x7fffffffu);
for (u32 i = 0; i <= 0x007fffffu; ++i)
{
Common::IntFloat x(i);
EXPECT_EQ(+0.f, Common::FlushToZero(x.f));
u32 i_tmp = i;
EXPECT_EQ(+0.f, Common::FlushToZero(Common::BitCast<float>(i_tmp)));
x.i = i | 0x80000000u;
EXPECT_EQ(-0.f, Common::FlushToZero(x.f));
i_tmp |= 0x80000000u;
EXPECT_EQ(-0.f, Common::FlushToZero(Common::BitCast<float>(i_tmp)));
x.i = dist(engine);
Common::IntFloat y(Common::FlushToZero(x.f));
EXPECT_EQ(x.i, y.i);
i_tmp = dist(engine);
EXPECT_EQ(i_tmp, Common::BitCast<u32>(Common::FlushToZero(Common::BitCast<float>(i_tmp))));
x.i |= 0x80000000u;
y.f = Common::FlushToZero(x.f);
EXPECT_EQ(x.i, y.i);
i_tmp |= 0x80000000u;
EXPECT_EQ(i_tmp, Common::BitCast<u32>(Common::FlushToZero(Common::BitCast<float>(i_tmp))));
}
}

13
Source/UnitTests/VideoCommon/VertexLoaderTest.cpp
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@ -10,8 +10,8 @@
#include <gtest/gtest.h> // NOLINT
#include "Common/BitUtils.h"
#include "Common/Common.h"
#include "Common/FloatUtils.h"
#include "VideoCommon/CPMemory.h"
#include "VideoCommon/DataReader.h"
#include "VideoCommon/OpcodeDecoding.h"
@ -72,14 +72,15 @@ protected:
m_src.Write<T, true>(val);
}
void ExpectOut(float val)
void ExpectOut(float expected)
{
// Read unswapped.
Common::IntFloat expected(val), actual(m_dst.Read<float, false>());
if (!actual.f || actual.f != actual.f)
EXPECT_EQ(expected.i, actual.i);
const float actual = m_dst.Read<float, false>();
if (!actual || actual != actual)
EXPECT_EQ(Common::BitCast<u32>(expected), Common::BitCast<u32>(actual));
else
EXPECT_EQ(expected.f, actual.f);
EXPECT_EQ(expected, actual);
}
void RunVertices(int count, int expected_count = -1)