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[llvm][ADT] Fix uint64_t array BitSet construction on 32-bit systems #162814

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Merged
merged 1 commit into from
Oct 10, 2025
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[llvm][ADT] Fix uint64_t array BitSet construction on 32-bit systems #162814

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11 changes: 8 additions & 3 deletions llvm/include/llvm/ADT/Bitset.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,10 +47,15 @@ class Bitset {
for (size_t I = 0; I != B.size(); ++I)
Bits[I] = B[I];
} else {
for (size_t I = 0; I != B.size(); ++I) {
unsigned BitsToAssign = NumBits;
for (size_t I = 0; I != B.size() && BitsToAssign; ++I) {
uint64_t Elt = B[I];
Bits[2 * I] = static_cast<uint32_t>(Elt);
Bits[2 * I + 1] = static_cast<uint32_t>(Elt >> 32);
// On a 32-bit system the storage type will be 32-bit, so we may only
// need half of a uint64_t.
for (size_t offset = 0; offset != 2 && BitsToAssign; ++offset) {
Bits[2 * I + offset] = static_cast<uint32_t>(Elt >> (32 * offset));
BitsToAssign = BitsToAssign >= 32 ? BitsToAssign - 32 : 0;
}
}
}
}
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27 changes: 27 additions & 0 deletions llvm/unittests/ADT/BitsetTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,14 +31,41 @@ class TestBitsetUInt64Array : public Bitset<NumBits> {

return true;
}

void verifyStorageSize(size_t elements_64_bit, size_t elements_32_bit) {
if constexpr (sizeof(uintptr_t) == sizeof(uint64_t))
EXPECT_EQ(sizeof(*this), elements_64_bit * sizeof(uintptr_t));
else
EXPECT_EQ(sizeof(*this), elements_32_bit * sizeof(uintptr_t));
}
};

TEST(BitsetTest, Construction) {
std::array<uint64_t, 2> TestVals = {0x123456789abcdef3, 0x1337d3a0b22c24};
TestBitsetUInt64Array<96> Test(TestVals);
EXPECT_TRUE(Test.verifyValue(TestVals));
Test.verifyStorageSize(2, 3);

TestBitsetUInt64Array<65> Test1(TestVals);
EXPECT_TRUE(Test1.verifyValue(TestVals));
Test1.verifyStorageSize(2, 3);

std::array<uint64_t, 1> TestSingleVal = {0x12345678abcdef99};

TestBitsetUInt64Array<64> Test64(TestSingleVal);
EXPECT_TRUE(Test64.verifyValue(TestSingleVal));
Test64.verifyStorageSize(1, 2);

TestBitsetUInt64Array<30> Test30(TestSingleVal);
EXPECT_TRUE(Test30.verifyValue(TestSingleVal));
Test30.verifyStorageSize(1, 1);

TestBitsetUInt64Array<32> Test32(TestSingleVal);
EXPECT_TRUE(Test32.verifyValue(TestSingleVal));
Test32.verifyStorageSize(1, 1);

TestBitsetUInt64Array<33> Test33(TestSingleVal);
EXPECT_TRUE(Test33.verifyValue(TestSingleVal));
Test33.verifyStorageSize(1, 2);
}
} // namespace
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