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APFloat: Fix maxnum and minnum with sNaN #112854

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Merged
merged 2 commits into from
Feb 27, 2025
Merged

APFloat: Fix maxnum and minnum with sNaN #112854

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ad7c6b6
APFloat: Fix maxnum and minnum with sNaN
wzssyqa Oct 18, 2024
cc90c8a
remove clang changes: should be another patch
wzssyqa Oct 23, 2024
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22 changes: 16 additions & 6 deletions llvm/include/llvm/ADT/APFloat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1515,11 +1515,16 @@ inline APFloat neg(APFloat X) {
return X;
}

/// Implements IEEE-754 2019 minimumNumber semantics. Returns the smaller of the
/// 2 arguments if both are not NaN. If either argument is a NaN, returns the
/// other argument. -0 is treated as ordered less than +0.
/// Implements IEEE-754 2008 minNum semantics. Returns the smaller of the
/// 2 arguments if both are not NaN. If either argument is a qNaN, returns the
/// other argument. If either argument is sNaN, return a qNaN.
/// -0 is treated as ordered less than +0.
LLVM_READONLY
inline APFloat minnum(const APFloat &A, const APFloat &B) {
if (A.isSignaling())
return A.makeQuiet();
if (B.isSignaling())
return B.makeQuiet();
if (A.isNaN())
return B;
if (B.isNaN())
Expand All @@ -1529,11 +1534,16 @@ inline APFloat minnum(const APFloat &A, const APFloat &B) {
return B < A ? B : A;
}

/// Implements IEEE-754 2019 maximumNumber semantics. Returns the larger of the
/// 2 arguments if both are not NaN. If either argument is a NaN, returns the
/// other argument. +0 is treated as ordered greater than -0.
/// Implements IEEE-754 2008 maxNum semantics. Returns the larger of the
/// 2 arguments if both are not NaN. If either argument is a qNaN, returns the
/// other argument. If either argument is sNaN, return a qNaN.
/// +0 is treated as ordered greater than -0.
LLVM_READONLY
inline APFloat maxnum(const APFloat &A, const APFloat &B) {
if (A.isSignaling())
return A.makeQuiet();
if (B.isSignaling())
return B.makeQuiet();
if (A.isNaN())
return B;
if (B.isNaN())
Expand Down
81 changes: 80 additions & 1 deletion llvm/unittests/ADT/APFloatTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -582,7 +582,46 @@ TEST(APFloatTest, MinNum) {
APFloat zp(0.0);
APFloat zn(-0.0);
EXPECT_EQ(-0.0, minnum(zp, zn).convertToDouble());
EXPECT_EQ(-0.0, minnum(zn, zp).convertToDouble());

APInt intPayload_89ab(64, 0x89ab);
APInt intPayload_cdef(64, 0xcdef);
APFloat nan_0123[2] = {APFloat::getNaN(APFloat::IEEEdouble(), false, 0x0123),
APFloat::getNaN(APFloat::IEEEdouble(), false, 0x0123)};
APFloat mnan_4567[2] = {APFloat::getNaN(APFloat::IEEEdouble(), true, 0x4567),
APFloat::getNaN(APFloat::IEEEdouble(), true, 0x4567)};
APFloat nan_89ab[2] = {
APFloat::getSNaN(APFloat::IEEEdouble(), false, &intPayload_89ab),
APFloat::getNaN(APFloat::IEEEdouble(), false, 0x89ab)};
APFloat mnan_cdef[2] = {
APFloat::getSNaN(APFloat::IEEEdouble(), true, &intPayload_cdef),
APFloat::getNaN(APFloat::IEEEdouble(), true, 0xcdef)};

for (APFloat n : {nan_0123[0], mnan_4567[0]})
for (APFloat f : {f1, f2, zn, zp}) {
APFloat res = minnum(f, n);
EXPECT_FALSE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(f));
res = minnum(n, f);
EXPECT_FALSE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(f));
}
for (auto n : {nan_89ab, mnan_cdef})
for (APFloat f : {f1, f2, zn, zp}) {
APFloat res = minnum(f, n[0]);
EXPECT_TRUE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(n[1]));
res = minnum(n[0], f);
EXPECT_TRUE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(n[1]));
}

// When NaN vs NaN, we should keep payload/sign of either one.
for (auto n1 : {nan_0123, mnan_4567, nan_89ab, mnan_cdef})
for (auto n2 : {nan_0123, mnan_4567, nan_89ab, mnan_cdef}) {
APFloat res = minnum(n1[0], n2[0]);
EXPECT_TRUE(res.bitwiseIsEqual(n1[1]) || res.bitwiseIsEqual(n2[1]));
EXPECT_FALSE(res.isSignaling());
}
}

TEST(APFloatTest, MaxNum) {
Expand All @@ -599,6 +638,46 @@ TEST(APFloatTest, MaxNum) {
APFloat zn(-0.0);
EXPECT_EQ(0.0, maxnum(zp, zn).convertToDouble());
EXPECT_EQ(0.0, maxnum(zn, zp).convertToDouble());

APInt intPayload_89ab(64, 0x89ab);
APInt intPayload_cdef(64, 0xcdef);
APFloat nan_0123[2] = {APFloat::getNaN(APFloat::IEEEdouble(), false, 0x0123),
APFloat::getNaN(APFloat::IEEEdouble(), false, 0x0123)};
APFloat mnan_4567[2] = {APFloat::getNaN(APFloat::IEEEdouble(), true, 0x4567),
APFloat::getNaN(APFloat::IEEEdouble(), true, 0x4567)};
APFloat nan_89ab[2] = {
APFloat::getSNaN(APFloat::IEEEdouble(), false, &intPayload_89ab),
APFloat::getNaN(APFloat::IEEEdouble(), false, 0x89ab)};
APFloat mnan_cdef[2] = {
APFloat::getSNaN(APFloat::IEEEdouble(), true, &intPayload_cdef),
APFloat::getNaN(APFloat::IEEEdouble(), true, 0xcdef)};

for (APFloat n : {nan_0123[0], mnan_4567[0]})
for (APFloat f : {f1, f2, zn, zp}) {
APFloat res = maxnum(f, n);
EXPECT_FALSE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(f));
res = maxnum(n, f);
EXPECT_FALSE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(f));
}
for (auto n : {nan_89ab, mnan_cdef})
for (APFloat f : {f1, f2, zn, zp}) {
APFloat res = maxnum(f, n[0]);
EXPECT_TRUE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(n[1]));
res = maxnum(n[0], f);
EXPECT_TRUE(res.isNaN());
EXPECT_TRUE(res.bitwiseIsEqual(n[1]));
}

// When NaN vs NaN, we should keep payload/sign of either one.
for (auto n1 : {nan_0123, mnan_4567, nan_89ab, mnan_cdef})
for (auto n2 : {nan_0123, mnan_4567, nan_89ab, mnan_cdef}) {
APFloat res = maxnum(n1[0], n2[0]);
EXPECT_TRUE(res.bitwiseIsEqual(n1[1]) || res.bitwiseIsEqual(n2[1]));
EXPECT_FALSE(res.isSignaling());
}
}

TEST(APFloatTest, Minimum) {
Expand Down
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