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Fix arithmetic right-shift by constants over 32 bits (#5994).

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This commit is contained in:
Wilson Snyder
2025-05-10 13:59:56 -04:00
parent d9dcde60a6
commit 0f528d136d
4 changed files with 50 additions and 15 deletions
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src/V3Number.cpp
+9 -15
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@@ -1853,23 +1853,17 @@ V3Number& V3Number::opShiftRS(const V3Number& lhs, const V3Number& rhs, uint32_t
NUM_ASSERT_LOGIC_ARGS2(lhs, rhs);
if (rhs.isFourState()) return setAllBitsX();
setZero();
for (int bit = 32; bit < rhs.width(); ++bit) {
for (int sbit = 0; sbit < width(); ++sbit) {
setBit(sbit, lhs.bitIs(lbits - 1)); // 0/1/X/Z
}
if (rhs.bitIs1(lbits - 1)) setAllBits1(); // -1 else 0
return *this; // shift of over 2^32 must be -1/0
}
const uint32_t rhsval = rhs.toUInt();
if (rhsval < static_cast<uint32_t>(lhs.width())) {
for (int bit = 0; bit < width(); ++bit) {
setBit(bit, lhs.bitIsExtend(bit + rhsval, lbits));
}
} else {
for (int bit = 0; bit < width(); ++bit) {
setBit(bit, lhs.bitIs(lbits - 1)); // 0/1/X/Z
const bool overflow = rhs.width() > 32 && !rhs.isBitsZero(rhs.width() - 1, 32);
if (!overflow) {
const uint32_t rhsval = rhs.toUInt();
if (rhsval < static_cast<uint32_t>(lhs.width())) {
for (int bit = 0; bit < width(); ++bit) {
setBit(bit, lhs.bitIsExtend(bit + rhsval, lbits));
}
return *this;
}
}
for (int bit = 0; bit < width(); ++bit) setBit(bit, lhs.bitIs(lbits - 1)); // '0/'1/'x/'z
return *this;
}