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[ConstantFPRange] Add support for fneg/fabs #162690

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Merged
merged 2 commits into from
Oct 10, 2025
Merged

[ConstantFPRange] Add support for fneg/fabs #162690

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cc99daa
[ConstantFPRange] Add support for fneg/fabs
dtcxzyw Oct 9, 2025
87869e4
[ConstantFPRange] Fix abs(nan)
dtcxzyw Oct 9, 2025
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6 changes: 6 additions & 0 deletions llvm/include/llvm/IR/ConstantFPRange.h
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Expand Up @@ -200,6 +200,12 @@ class [[nodiscard]] ConstantFPRange {
/// with another range. The resultant range is guaranteed to include the
/// elements of both sets, but may contain more.
LLVM_ABI ConstantFPRange unionWith(const ConstantFPRange &CR) const;

/// Calculate absolute value range.
LLVM_ABI ConstantFPRange abs() const;

/// Calculate range of negated values.
LLVM_ABI ConstantFPRange negate() const;
};

inline raw_ostream &operator<<(raw_ostream &OS, const ConstantFPRange &CR) {
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20 changes: 20 additions & 0 deletions llvm/lib/IR/ConstantFPRange.cpp
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Expand Up @@ -391,3 +391,23 @@ ConstantFPRange ConstantFPRange::unionWith(const ConstantFPRange &CR) const {
return ConstantFPRange(minnum(Lower, CR.Lower), maxnum(Upper, CR.Upper),
MayBeQNaN | CR.MayBeQNaN, MayBeSNaN | CR.MayBeSNaN);
}

ConstantFPRange ConstantFPRange::abs() const {
if (isNaNOnly())
return *this;
// Check if the range is all non-negative or all non-positive.
if (Lower.isNegative() == Upper.isNegative()) {
if (Lower.isNegative())
return negate();
return *this;
}
Comment on lines +399 to +403
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Simpler:

Suggested change
if (Lower.isNegative() == Upper.isNegative()) {
if (Lower.isNegative())
return negate();
return *this;
}
if (!Lower.isNegative())
return *this;
if (Upper.isNegative())
return negate();

// The range contains both positive and negative values.
APFloat NewLower = APFloat::getZero(getSemantics());
APFloat NewUpper = maxnum(-Lower, Upper);
return ConstantFPRange(std::move(NewLower), std::move(NewUpper), MayBeQNaN,
MayBeSNaN);
}

ConstantFPRange ConstantFPRange::negate() const {
return ConstantFPRange(-Upper, -Lower, MayBeQNaN, MayBeSNaN);
}
35 changes: 35 additions & 0 deletions llvm/unittests/IR/ConstantFPRangeTest.cpp
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Expand Up @@ -767,4 +767,39 @@ TEST_F(ConstantFPRangeTest, makeExactFCmpRegion) {
}
}

TEST_F(ConstantFPRangeTest, abs) {
EXPECT_EQ(Full.abs(),
ConstantFPRange(APFloat::getZero(Sem, /*Negative=*/false),
APFloat::getInf(Sem, /*Negative=*/false),
/*MayBeQNaN=*/true,
/*MayBeSNaN=*/true));
EXPECT_EQ(Empty.abs(), Empty);
EXPECT_EQ(Zero.abs(), PosZero);
EXPECT_EQ(PosInf.abs(), PosInf);
EXPECT_EQ(NegInf.abs(), PosInf);
EXPECT_EQ(Some.abs(), SomePos);
EXPECT_EQ(SomeNeg.abs(), SomePos);
EXPECT_EQ(NaN.abs(), NaN);
EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)).abs(),
ConstantFPRange::getNonNaN(APFloat(0.0), APFloat(3.0)));
EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)).abs(),
ConstantFPRange::getNonNaN(APFloat(0.0), APFloat(3.0)));
}

TEST_F(ConstantFPRangeTest, negate) {
EXPECT_EQ(Full.negate(), Full);
EXPECT_EQ(Empty.negate(), Empty);
EXPECT_EQ(Zero.negate(), Zero);
EXPECT_EQ(PosInf.negate(), NegInf);
EXPECT_EQ(NegInf.negate(), PosInf);
EXPECT_EQ(Some.negate(), Some);
EXPECT_EQ(SomePos.negate(), SomeNeg);
EXPECT_EQ(SomeNeg.negate(), SomePos);
EXPECT_EQ(NaN.negate(), NaN);
EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)).negate(),
ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)));
EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)).negate(),
ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)));
}

} // anonymous namespace