[ConstantFPRange] Add support for mul/div #163063
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dtcxzyw
requested review from
andykaylor,
arsenm,
jayfoad,
jcranmer-intel and
nikic
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@llvm/pr-subscribers-llvm-ir Author: Yingwei Zheng (dtcxzyw) ChangesThis patch adds support for fmul/fdiv operations. I will leave the frem support to a separate patch because its implementation is quite different from fmul/fdiv. Full diff: https://github.com/llvm/llvm-project/pull/163063.diff 3 Files Affected:
diff --git a/llvm/include/llvm/IR/ConstantFPRange.h b/llvm/include/llvm/IR/ConstantFPRange.h
index 39dc7c100d6f7..9e169c00306b4 100644
--- a/llvm/include/llvm/IR/ConstantFPRange.h
+++ b/llvm/include/llvm/IR/ConstantFPRange.h
@@ -230,6 +230,15 @@ class [[nodiscard]] ConstantFPRange {
/// Return a new range representing the possible values resulting
/// from a subtraction of a value in this range and a value in \p Other.
LLVM_ABI ConstantFPRange sub(const ConstantFPRange &Other) const;
+
+ /// Return a new range representing the possible values resulting
+ /// from a multiplication of a value in this range and a value in \p Other.
+ LLVM_ABI ConstantFPRange mul(const ConstantFPRange &Other) const;
+
+ /// Return a new range representing the possible values resulting
+ /// from a division of a value in this range and a value in
+ /// \p Other.
+ LLVM_ABI ConstantFPRange div(const ConstantFPRange &Other) const;
};
inline raw_ostream &operator<<(raw_ostream &OS, const ConstantFPRange &CR) {
diff --git a/llvm/lib/IR/ConstantFPRange.cpp b/llvm/lib/IR/ConstantFPRange.cpp
index 51d2e215c980c..e1822503063dc 100644
--- a/llvm/lib/IR/ConstantFPRange.cpp
+++ b/llvm/lib/IR/ConstantFPRange.cpp
@@ -506,3 +506,147 @@ ConstantFPRange ConstantFPRange::sub(const ConstantFPRange &Other) const {
// fsub X, Y = fadd X, (fneg Y)
return add(Other.negate());
}
+
+/// Represent a contiguous range of values sharing the same sign.
+struct SameSignRange {
+ bool HasZero;
+ bool HasNonZero;
+ bool HasInf;
+ // The lower and upper bounds of the range (inclusive).
+ // The sign is dropped and infinities are excluded.
+ std::optional<std::pair<APFloat, APFloat>> FinitePart;
+
+ explicit SameSignRange(const APFloat &Lower, const APFloat &Upper)
+ : HasZero(Lower.isZero()), HasNonZero(!Upper.isZero()),
+ HasInf(Upper.isInfinity()) {
+ assert(!Lower.isNegative() && !Upper.isNegative() &&
+ "The sign should be dropped.");
+ assert(strictCompare(Lower, Upper) != APFloat::cmpGreaterThan &&
+ "Empty set.");
+ if (!Lower.isInfinity())
+ FinitePart = {Lower,
+ HasInf ? APFloat::getLargest(Lower.getSemantics()) : Upper};
+ }
+};
+
+/// Split the range into positive and negative components.
+static void splitPosNeg(const APFloat &Lower, const APFloat &Upper,
+ std::optional<SameSignRange> &NegPart,
+ std::optional<SameSignRange> &PosPart) {
+ assert(strictCompare(Lower, Upper) != APFloat::cmpGreaterThan &&
+ "Non-NaN part is empty.");
+ if (Lower.isNegative() == Upper.isNegative()) {
+ if (Lower.isNegative())
+ NegPart = SameSignRange{abs(Upper), abs(Lower)};
+ else
+ PosPart = SameSignRange{Lower, Upper};
+ return;
+ }
+ auto &Sem = Lower.getSemantics();
+ NegPart = SameSignRange{APFloat::getZero(Sem), abs(Lower)};
+ PosPart = SameSignRange{APFloat::getZero(Sem), Upper};
+}
+
+ConstantFPRange ConstantFPRange::mul(const ConstantFPRange &Other) const {
+ auto &Sem = getSemantics();
+ bool ResMayBeQNaN = ((MayBeQNaN || MayBeSNaN) && !Other.isEmptySet()) ||
+ ((Other.MayBeQNaN || Other.MayBeSNaN) && !isEmptySet());
+ if (isNaNOnly() || Other.isNaNOnly())
+ return getNaNOnly(Sem, /*MayBeQNaN=*/ResMayBeQNaN,
+ /*MayBeSNaN=*/false);
+ std::optional<SameSignRange> LHSNeg, LHSPos, RHSNeg, RHSPos;
+ splitPosNeg(Lower, Upper, LHSNeg, LHSPos);
+ splitPosNeg(Other.Lower, Other.Upper, RHSNeg, RHSPos);
+ APFloat ResLower = APFloat::getInf(Sem, /*Negative=*/false);
+ APFloat ResUpper = APFloat::getInf(Sem, /*Negative=*/true);
+ auto Update = [&](std::optional<SameSignRange> &LHS,
+ std::optional<SameSignRange> &RHS, bool Negative) {
+ if (!LHS || !RHS)
+ return;
+ // 0 * inf = QNaN
+ ResMayBeQNaN |= LHS->HasZero && RHS->HasInf;
+ ResMayBeQNaN |= RHS->HasZero && LHS->HasInf;
+ // NonZero * inf = inf
+ if ((LHS->HasInf && RHS->HasNonZero) || (RHS->HasInf && LHS->HasNonZero))
+ (Negative ? ResLower : ResUpper) = APFloat::getInf(Sem, Negative);
+ // Finite * Finite
+ if (LHS->FinitePart && RHS->FinitePart) {
+ APFloat NewLower = LHS->FinitePart->first * RHS->FinitePart->first;
+ APFloat NewUpper = LHS->FinitePart->second * RHS->FinitePart->second;
+ if (Negative) {
+ ResLower = minnum(ResLower, -NewUpper);
+ ResUpper = maxnum(ResUpper, -NewLower);
+ } else {
+ ResLower = minnum(ResLower, NewLower);
+ ResUpper = maxnum(ResUpper, NewUpper);
+ }
+ }
+ };
+ Update(LHSNeg, RHSNeg, /*Negative=*/false);
+ Update(LHSNeg, RHSPos, /*Negative=*/true);
+ Update(LHSPos, RHSNeg, /*Negative=*/true);
+ Update(LHSPos, RHSPos, /*Negative=*/false);
+ return ConstantFPRange(ResLower, ResUpper, ResMayBeQNaN, /*MayBeSNaN=*/false);
+}
+
+ConstantFPRange ConstantFPRange::div(const ConstantFPRange &Other) const {
+ auto &Sem = getSemantics();
+ bool ResMayBeQNaN = ((MayBeQNaN || MayBeSNaN) && !Other.isEmptySet()) ||
+ ((Other.MayBeQNaN || Other.MayBeSNaN) && !isEmptySet());
+ if (isNaNOnly() || Other.isNaNOnly())
+ return getNaNOnly(Sem, /*MayBeQNaN=*/ResMayBeQNaN,
+ /*MayBeSNaN=*/false);
+ std::optional<SameSignRange> LHSNeg, LHSPos, RHSNeg, RHSPos;
+ splitPosNeg(Lower, Upper, LHSNeg, LHSPos);
+ splitPosNeg(Other.Lower, Other.Upper, RHSNeg, RHSPos);
+ APFloat ResLower = APFloat::getInf(Sem, /*Negative=*/false);
+ APFloat ResUpper = APFloat::getInf(Sem, /*Negative=*/true);
+ auto Update = [&](std::optional<SameSignRange> &LHS,
+ std::optional<SameSignRange> &RHS, bool Negative) {
+ if (!LHS || !RHS)
+ return;
+ // inf / inf = QNaN 0 / 0 = QNaN
+ ResMayBeQNaN |= LHS->HasInf && RHS->HasInf;
+ ResMayBeQNaN |= LHS->HasZero && RHS->HasZero;
+ // It is not straightforward to infer HasNonZeroFinite = HasFinite &&
+ // HasNonZero. By definitions we have:
+ // HasFinite = HasNonZeroFinite || HasZero
+ // HasNonZero = HasNonZeroFinite || HasInf
+ // Since the range is contiguous, if both HasFinite and HasNonZero are true,
+ // HasNonZeroFinite must be true.
+ bool LHSHasNonZeroFinite = LHS->FinitePart && LHS->HasNonZero;
+ bool RHSHasNonZeroFinite = RHS->FinitePart && RHS->HasNonZero;
+ // inf / Finite = inf FiniteNonZero / 0 = inf
+ if ((LHS->HasInf && RHS->FinitePart) ||
+ (LHSHasNonZeroFinite && RHS->HasZero))
+ (Negative ? ResLower : ResUpper) = APFloat::getInf(Sem, Negative);
+ // Finite / inf = 0
+ if (LHS->FinitePart && RHS->HasInf) {
+ APFloat Zero = APFloat::getZero(Sem, /*Negative=*/Negative);
+ ResLower = minnum(ResLower, Zero);
+ ResUpper = maxnum(ResUpper, Zero);
+ }
+ // Finite / FiniteNonZero
+ if (LHS->FinitePart && RHSHasNonZeroFinite) {
+ assert(!RHS->FinitePart->second.isZero() &&
+ "Divisor should be non-zero.");
+ APFloat NewLower = LHS->FinitePart->first / RHS->FinitePart->second;
+ APFloat NewUpper = LHS->FinitePart->second /
+ (RHS->FinitePart->first.isZero()
+ ? APFloat::getSmallest(Sem, /*Negative=*/false)
+ : RHS->FinitePart->first);
+ if (Negative) {
+ ResLower = minnum(ResLower, -NewUpper);
+ ResUpper = maxnum(ResUpper, -NewLower);
+ } else {
+ ResLower = minnum(ResLower, NewLower);
+ ResUpper = maxnum(ResUpper, NewUpper);
+ }
+ }
+ };
+ Update(LHSNeg, RHSNeg, /*Negative=*/false);
+ Update(LHSNeg, RHSPos, /*Negative=*/true);
+ Update(LHSPos, RHSNeg, /*Negative=*/true);
+ Update(LHSPos, RHSPos, /*Negative=*/false);
+ return ConstantFPRange(ResLower, ResUpper, ResMayBeQNaN, /*MayBeSNaN=*/false);
+}
diff --git a/llvm/unittests/IR/ConstantFPRangeTest.cpp b/llvm/unittests/IR/ConstantFPRangeTest.cpp
index cf9b31cf88480..892865c06ac79 100644
--- a/llvm/unittests/IR/ConstantFPRangeTest.cpp
+++ b/llvm/unittests/IR/ConstantFPRangeTest.cpp
@@ -1065,4 +1065,113 @@ TEST_F(ConstantFPRangeTest, sub) {
#endif
}
+TEST_F(ConstantFPRangeTest, mul) {
+ EXPECT_EQ(Full.mul(Full), NonNaN.unionWith(QNaN));
+ EXPECT_EQ(Full.mul(Empty), Empty);
+ EXPECT_EQ(Empty.mul(Full), Empty);
+ EXPECT_EQ(Empty.mul(Empty), Empty);
+ EXPECT_EQ(One.mul(One), ConstantFPRange(APFloat(1.0)));
+ EXPECT_EQ(Some.mul(Some),
+ ConstantFPRange::getNonNaN(APFloat(-9.0), APFloat(9.0)));
+ EXPECT_EQ(SomePos.mul(SomeNeg),
+ ConstantFPRange::getNonNaN(APFloat(-9.0), APFloat(-0.0)));
+ EXPECT_EQ(PosInf.mul(PosInf), PosInf);
+ EXPECT_EQ(NegInf.mul(NegInf), PosInf);
+ EXPECT_EQ(PosInf.mul(Finite), NonNaN.unionWith(QNaN));
+ EXPECT_EQ(NegInf.mul(Finite), NonNaN.unionWith(QNaN));
+ EXPECT_EQ(PosInf.mul(NegInf), NegInf);
+ EXPECT_EQ(NegInf.mul(PosInf), NegInf);
+ EXPECT_EQ(PosZero.mul(NegZero), NegZero);
+ EXPECT_EQ(PosZero.mul(Zero), Zero);
+ EXPECT_EQ(NegZero.mul(NegZero), PosZero);
+ EXPECT_EQ(NegZero.mul(Zero), Zero);
+ EXPECT_EQ(NaN.mul(NaN), QNaN);
+ EXPECT_EQ(NaN.mul(Finite), QNaN);
+
+#if defined(EXPENSIVE_CHECKS)
+ EnumerateTwoInterestingConstantFPRanges(
+ [](const ConstantFPRange &LHS, const ConstantFPRange &RHS) {
+ ConstantFPRange Res = LHS.mul(RHS);
+ ConstantFPRange Expected =
+ ConstantFPRange::getEmpty(LHS.getSemantics());
+ EnumerateValuesInConstantFPRange(
+ LHS,
+ [&](const APFloat &LHSC) {
+ EnumerateValuesInConstantFPRange(
+ RHS,
+ [&](const APFloat &RHSC) {
+ APFloat Prod = LHSC * RHSC;
+ EXPECT_TRUE(Res.contains(Prod))
+ << "Wrong result for " << LHS << " * " << RHS
+ << ". The result " << Res << " should contain " << Prod;
+ if (!Expected.contains(Prod))
+ Expected = Expected.unionWith(ConstantFPRange(Prod));
+ },
+ /*IgnoreNaNPayload=*/true);
+ },
+ /*IgnoreNaNPayload=*/true);
+ EXPECT_EQ(Res, Expected)
+ << "Suboptimal result for " << LHS << " * " << RHS << ". Expected "
+ << Expected << ", but got " << Res;
+ },
+ SparseLevel::SpecialValuesOnly);
+#endif
+}
+
+TEST_F(ConstantFPRangeTest, div) {
+ EXPECT_EQ(Full.div(Full), NonNaN.unionWith(QNaN));
+ EXPECT_EQ(Full.div(Empty), Empty);
+ EXPECT_EQ(Empty.div(Full), Empty);
+ EXPECT_EQ(Empty.div(Empty), Empty);
+ EXPECT_EQ(One.div(One), ConstantFPRange(APFloat(1.0)));
+ EXPECT_EQ(Some.div(Some), NonNaN.unionWith(QNaN));
+ EXPECT_EQ(SomePos.div(SomeNeg),
+ ConstantFPRange(APFloat::getInf(Sem, /*Negative=*/true),
+ APFloat::getZero(Sem, /*Negative=*/true),
+ /*MayBeQNaN=*/true, /*MayBeSNaN=*/false));
+ EXPECT_EQ(PosInf.div(PosInf), QNaN);
+ EXPECT_EQ(NegInf.div(NegInf), QNaN);
+ EXPECT_EQ(PosInf.div(Finite), NonNaN);
+ EXPECT_EQ(NegInf.div(Finite), NonNaN);
+ EXPECT_EQ(PosInf.div(NegInf), QNaN);
+ EXPECT_EQ(NegInf.div(PosInf), QNaN);
+ EXPECT_EQ(Zero.div(Zero), QNaN);
+ EXPECT_EQ(SomePos.div(PosInf), PosZero);
+ EXPECT_EQ(SomeNeg.div(PosInf), NegZero);
+ EXPECT_EQ(PosInf.div(SomePos), PosInf);
+ EXPECT_EQ(NegInf.div(SomeNeg), PosInf);
+ EXPECT_EQ(NegInf.div(Some), NonNaN);
+ EXPECT_EQ(NaN.div(NaN), QNaN);
+ EXPECT_EQ(NaN.div(Finite), QNaN);
+
+#if defined(EXPENSIVE_CHECKS)
+ EnumerateTwoInterestingConstantFPRanges(
+ [](const ConstantFPRange &LHS, const ConstantFPRange &RHS) {
+ ConstantFPRange Res = LHS.div(RHS);
+ ConstantFPRange Expected =
+ ConstantFPRange::getEmpty(LHS.getSemantics());
+ EnumerateValuesInConstantFPRange(
+ LHS,
+ [&](const APFloat &LHSC) {
+ EnumerateValuesInConstantFPRange(
+ RHS,
+ [&](const APFloat &RHSC) {
+ APFloat Val = LHSC / RHSC;
+ EXPECT_TRUE(Res.contains(Val))
+ << "Wrong result for " << LHS << " / " << RHS
+ << ". The result " << Res << " should contain " << Val;
+ if (!Expected.contains(Val))
+ Expected = Expected.unionWith(ConstantFPRange(Val));
+ },
+ /*IgnoreNaNPayload=*/true);
+ },
+ /*IgnoreNaNPayload=*/true);
+ EXPECT_EQ(Res, Expected)
+ << "Suboptimal result for " << LHS << " / " << RHS << ". Expected "
+ << Expected << ", but got " << Res;
+ },
+ SparseLevel::SpecialValuesOnly);
+#endif
+}
+
} // anonymous namespace
|
arsenm
approved these changes
Oct 13, 2025
| PosPart = SameSignRange{APFloat::getZero(Sem), Upper}; | ||
| } | ||
|
|
||
| ConstantFPRange ConstantFPRange::mul(const ConstantFPRange &Other) const { |
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At some point should probably thread the rounding mode arguments through
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/51/builds/25169 Here is the relevant piece of the build log for the reference |
akadutta
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Oct 14, 2025
This patch adds support for fmul/fdiv operations.
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This patch adds support for fmul/fdiv operations. I will leave the frem support to a separate patch because its implementation is quite different from fmul/fdiv.