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[APFloat] Enlarge ExponentType to 32bit integer
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Enlarge the size of ExponentType from 16bit integer to 32bit. This is
required to prevent exponent overflow/underflow.

Note that IEEEFloat size and alignment don't change in 64bit or 32bit
compilation targets (and in turn, neither does APFloat).

Fixes PR34851.

Differential Revision: https://reviews.llvm.org/D69771
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@ekatz
ekatz committed Nov 22, 2019
1 parent 8ca7871 commit 8606d01
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Showing 2 changed files with 118 additions and 16 deletions.
2 changes: 1 addition & 1 deletion llvm/include/llvm/ADT/APFloat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,7 @@ struct APFloatBase {
static const unsigned integerPartWidth = APInt::APINT_BITS_PER_WORD;

/// A signed type to represent a floating point numbers unbiased exponent.
typedef signed short ExponentType;
typedef int32_t ExponentType;

/// \name Floating Point Semantics.
/// @{
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132 changes: 117 additions & 15 deletions llvm/unittests/ADT/APFloatTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2335,21 +2335,28 @@ TEST(APFloatTest, multiply) {
APFloat PSmallestValue = APFloat::getSmallest(APFloat::IEEEsingle(), false);
APFloat MSmallestValue = APFloat::getSmallest(APFloat::IEEEsingle(), true);
APFloat PSmallestNormalized =
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), false);
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), false);
APFloat MSmallestNormalized =
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), true);
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), true);

APFloat MaxQuad(APFloat::IEEEquad(),
"0x1.ffffffffffffffffffffffffffffp+16383");
APFloat MinQuad(APFloat::IEEEquad(),
"0x0.0000000000000000000000000001p-16382");
APFloat NMinQuad(APFloat::IEEEquad(),
"-0x0.0000000000000000000000000001p-16382");

const int OverflowStatus = APFloat::opOverflow | APFloat::opInexact;
const int UnderflowStatus = APFloat::opUnderflow | APFloat::opInexact;

const unsigned NumTests = 169;
struct {
APFloat x;
APFloat y;
const char *result;
int status;
int category;
} SpecialCaseTests[NumTests] = {
APFloat::roundingMode roundingMode = APFloat::rmNearestTiesToEven;
} SpecialCaseTests[] = {
{ PInf, PInf, "inf", APFloat::opOK, APFloat::fcInfinity },
{ PInf, MInf, "-inf", APFloat::opOK, APFloat::fcInfinity },
{ PInf, PZero, "nan", APFloat::opInvalidOp, APFloat::fcNaN },
Expand Down Expand Up @@ -2587,15 +2594,70 @@ TEST(APFloatTest, multiply) {
{ MSmallestNormalized, PSmallestValue, "-0x0p+0", UnderflowStatus, APFloat::fcZero },
{ MSmallestNormalized, MSmallestValue, "0x0p+0", UnderflowStatus, APFloat::fcZero },
{ MSmallestNormalized, PSmallestNormalized, "-0x0p+0", UnderflowStatus, APFloat::fcZero },
{ MSmallestNormalized, MSmallestNormalized, "0x0p+0", UnderflowStatus, APFloat::fcZero }
{ MSmallestNormalized, MSmallestNormalized, "0x0p+0", UnderflowStatus, APFloat::fcZero },

{MaxQuad, MinQuad, "0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmNearestTiesToEven},
{MaxQuad, MinQuad, "0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmTowardPositive},
{MaxQuad, MinQuad, "0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmTowardNegative},
{MaxQuad, MinQuad, "0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmTowardZero},
{MaxQuad, MinQuad, "0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmNearestTiesToAway},

{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmNearestTiesToEven},
{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmTowardPositive},
{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmTowardNegative},
{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmTowardZero},
{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp-111", APFloat::opOK,
APFloat::fcNormal, APFloat::rmNearestTiesToAway},

{MaxQuad, MaxQuad, "inf", OverflowStatus, APFloat::fcInfinity,
APFloat::rmNearestTiesToEven},
{MaxQuad, MaxQuad, "inf", OverflowStatus, APFloat::fcInfinity,
APFloat::rmTowardPositive},
{MaxQuad, MaxQuad, "0x1.ffffffffffffffffffffffffffffp+16383",
APFloat::opInexact, APFloat::fcNormal, APFloat::rmTowardNegative},
{MaxQuad, MaxQuad, "0x1.ffffffffffffffffffffffffffffp+16383",
APFloat::opInexact, APFloat::fcNormal, APFloat::rmTowardZero},
{MaxQuad, MaxQuad, "inf", OverflowStatus, APFloat::fcInfinity,
APFloat::rmNearestTiesToAway},

{MinQuad, MinQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToEven},
{MinQuad, MinQuad, "0x0.0000000000000000000000000001p-16382",
UnderflowStatus, APFloat::fcNormal, APFloat::rmTowardPositive},
{MinQuad, MinQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardNegative},
{MinQuad, MinQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardZero},
{MinQuad, MinQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToAway},

{MinQuad, NMinQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToEven},
{MinQuad, NMinQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardPositive},
{MinQuad, NMinQuad, "-0x0.0000000000000000000000000001p-16382",
UnderflowStatus, APFloat::fcNormal, APFloat::rmTowardNegative},
{MinQuad, NMinQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardZero},
{MinQuad, NMinQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToAway},
};

for (size_t i = 0; i < NumTests; ++i) {
for (size_t i = 0; i < array_lengthof(SpecialCaseTests); ++i) {
APFloat x(SpecialCaseTests[i].x);
APFloat y(SpecialCaseTests[i].y);
APFloat::opStatus status = x.multiply(y, APFloat::rmNearestTiesToEven);
APFloat::opStatus status = x.multiply(y, SpecialCaseTests[i].roundingMode);

APFloat result(APFloat::IEEEsingle(), SpecialCaseTests[i].result);
APFloat result(x.getSemantics(), SpecialCaseTests[i].result);

EXPECT_TRUE(result.bitwiseIsEqual(x));
EXPECT_TRUE((int)status == SpecialCaseTests[i].status);
Expand Down Expand Up @@ -2624,21 +2686,28 @@ TEST(APFloatTest, divide) {
APFloat PSmallestValue = APFloat::getSmallest(APFloat::IEEEsingle(), false);
APFloat MSmallestValue = APFloat::getSmallest(APFloat::IEEEsingle(), true);
APFloat PSmallestNormalized =
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), false);
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), false);
APFloat MSmallestNormalized =
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), true);
APFloat::getSmallestNormalized(APFloat::IEEEsingle(), true);

APFloat MaxQuad(APFloat::IEEEquad(),
"0x1.ffffffffffffffffffffffffffffp+16383");
APFloat MinQuad(APFloat::IEEEquad(),
"0x0.0000000000000000000000000001p-16382");
APFloat NMinQuad(APFloat::IEEEquad(),
"-0x0.0000000000000000000000000001p-16382");

const int OverflowStatus = APFloat::opOverflow | APFloat::opInexact;
const int UnderflowStatus = APFloat::opUnderflow | APFloat::opInexact;

const unsigned NumTests = 169;
struct {
APFloat x;
APFloat y;
const char *result;
int status;
int category;
} SpecialCaseTests[NumTests] = {
APFloat::roundingMode roundingMode = APFloat::rmNearestTiesToEven;
} SpecialCaseTests[] = {
{ PInf, PInf, "nan", APFloat::opInvalidOp, APFloat::fcNaN },
{ PInf, MInf, "nan", APFloat::opInvalidOp, APFloat::fcNaN },
{ PInf, PZero, "inf", APFloat::opOK, APFloat::fcInfinity },
Expand Down Expand Up @@ -2877,14 +2946,47 @@ TEST(APFloatTest, divide) {
{ MSmallestNormalized, MSmallestValue, "0x1p+23", APFloat::opOK, APFloat::fcNormal },
{ MSmallestNormalized, PSmallestNormalized, "-0x1p+0", APFloat::opOK, APFloat::fcNormal },
{ MSmallestNormalized, MSmallestNormalized, "0x1p+0", APFloat::opOK, APFloat::fcNormal },

{MaxQuad, NMinQuad, "-inf", OverflowStatus, APFloat::fcInfinity,
APFloat::rmNearestTiesToEven},
{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp+16383",
APFloat::opInexact, APFloat::fcNormal, APFloat::rmTowardPositive},
{MaxQuad, NMinQuad, "-inf", OverflowStatus, APFloat::fcInfinity,
APFloat::rmTowardNegative},
{MaxQuad, NMinQuad, "-0x1.ffffffffffffffffffffffffffffp+16383",
APFloat::opInexact, APFloat::fcNormal, APFloat::rmTowardZero},
{MaxQuad, NMinQuad, "-inf", OverflowStatus, APFloat::fcInfinity,
APFloat::rmNearestTiesToAway},

{MinQuad, MaxQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToEven},
{MinQuad, MaxQuad, "0x0.0000000000000000000000000001p-16382",
UnderflowStatus, APFloat::fcNormal, APFloat::rmTowardPositive},
{MinQuad, MaxQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardNegative},
{MinQuad, MaxQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardZero},
{MinQuad, MaxQuad, "0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToAway},

{NMinQuad, MaxQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToEven},
{NMinQuad, MaxQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardPositive},
{NMinQuad, MaxQuad, "-0x0.0000000000000000000000000001p-16382",
UnderflowStatus, APFloat::fcNormal, APFloat::rmTowardNegative},
{NMinQuad, MaxQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmTowardZero},
{NMinQuad, MaxQuad, "-0", UnderflowStatus, APFloat::fcZero,
APFloat::rmNearestTiesToAway},
};

for (size_t i = 0; i < NumTests; ++i) {
for (size_t i = 0; i < array_lengthof(SpecialCaseTests); ++i) {
APFloat x(SpecialCaseTests[i].x);
APFloat y(SpecialCaseTests[i].y);
APFloat::opStatus status = x.divide(y, APFloat::rmNearestTiesToEven);
APFloat::opStatus status = x.divide(y, SpecialCaseTests[i].roundingMode);

APFloat result(APFloat::IEEEsingle(), SpecialCaseTests[i].result);
APFloat result(x.getSemantics(), SpecialCaseTests[i].result);

EXPECT_TRUE(result.bitwiseIsEqual(x));
EXPECT_TRUE((int)status == SpecialCaseTests[i].status);
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