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[ADT] Fix a bug in PackedVector::setValue for signed types #159239

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Merged
merged 1 commit into from
Sep 28, 2025
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[ADT] Fix a bug in PackedVector::setValue for signed types #159239

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2 changes: 2 additions & 0 deletions llvm/include/llvm/ADT/PackedVector.h
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,8 @@ class PackedVectorBase<T, BitNum, BitVectorTy, true> {
if (val < 0) {
val = ~val;
Bits.set((Idx * BitNum) + BitNum - 1);
} else {
Bits.reset((Idx * BitNum) + BitNum - 1);
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I'd expect signed types to be disallowed?

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The author seems to mean to support signed types as far as I can tell from PackedVectorBase.

template <typename T, unsigned BitNum, typename BitVectorTy, bool isSigned>
class PackedVectorBase;

template <typename T, unsigned BitNum, typename BitVectorTy>
class PackedVectorBase<T, BitNum, BitVectorTy, false> {
  :
  :
};

template <typename T, unsigned BitNum, typename BitVectorTy>
class PackedVectorBase<T, BitNum, BitVectorTy, true> {
  :
  :
};

}
assert((val >> (BitNum-1)) == 0 && "value is too big");
for (unsigned i = 0; i != BitNum-1; ++i)
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8 changes: 8 additions & 0 deletions llvm/unittests/ADT/PackedVectorTest.cpp
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Expand Up @@ -71,6 +71,14 @@ TEST(PackedVectorTest, RawBitsSize) {
EXPECT_EQ(12u, Vec.raw_bits().size());
}

TEST(PackedVectorTest, SignedValueOverwrite) {
PackedVector<signed, 4> Vec(1);
Vec[0] = -1;
EXPECT_EQ(-1, Vec[0]);
Vec[0] = 1;
EXPECT_EQ(1, Vec[0]);
}

#ifdef EXPECT_DEBUG_DEATH

TEST(PackedVectorTest, UnsignedValues) {
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