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[clang][Interp] Fix value truncation when casting int128 to smaller size #67961

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Merged
merged 1 commit into from
Oct 3, 2023
Merged

[clang][Interp] Fix value truncation when casting int128 to smaller size #67961

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22 changes: 14 additions & 8 deletions clang/lib/AST/Interp/IntegralAP.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,12 @@ template <unsigned Bits, bool Signed> class Integral;
class Boolean;

template <bool Signed> class IntegralAP final {
private:
template <typename T> static T truncateCast(const APSInt &V) {
return std::is_signed_v<T> ? V.trunc(sizeof(T) * 8).getSExtValue()
: V.trunc(sizeof(T) * 8).getZExtValue();
}

public:
APSInt V;

Expand All @@ -55,14 +61,14 @@ template <bool Signed> class IntegralAP final {
bool operator<=(IntegralAP RHS) const { return V <= RHS.V; }

explicit operator bool() const { return !V.isZero(); }
explicit operator int8_t() const { return V.getSExtValue(); }
explicit operator uint8_t() const { return V.getZExtValue(); }
explicit operator int16_t() const { return V.getSExtValue(); }
explicit operator uint16_t() const { return V.getZExtValue(); }
explicit operator int32_t() const { return V.getSExtValue(); }
explicit operator uint32_t() const { return V.getZExtValue(); }
explicit operator int64_t() const { return V.getSExtValue(); }
explicit operator uint64_t() const { return V.getZExtValue(); }
explicit operator int8_t() const { return truncateCast<int8_t>(V); }
explicit operator uint8_t() const { return truncateCast<uint8_t>(V); }
explicit operator int16_t() const { return truncateCast<int16_t>(V); }
explicit operator uint16_t() const { return truncateCast<uint16_t>(V); }
explicit operator int32_t() const { return truncateCast<int32_t>(V); }
explicit operator uint32_t() const { return truncateCast<uint32_t>(V); }
explicit operator int64_t() const { return truncateCast<int64_t>(V); }
explicit operator uint64_t() const { return truncateCast<uint64_t>(V); }

template <typename T> static IntegralAP from(T Value, unsigned NumBits = 0) {
assert(NumBits > 0);
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10 changes: 9 additions & 1 deletion clang/test/AST/Interp/literals.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ namespace i128 {
static_assert(Two == 2, "");

constexpr uint128_t AllOnes = ~static_cast<uint128_t>(0);
static_assert(AllOnes == static_cast<uint128_t>(-1), "");
static_assert(AllOnes == UINT128_MAX, "");

#if __cplusplus >= 201402L
template <typename T>
Expand All @@ -70,6 +70,14 @@ namespace i128 {
static_assert(CastFrom<double>(12) == 12, "");
static_assert(CastFrom<long double>(12) == 12, "");

static_assert(CastFrom<char>(AllOnes) == -1, "");
static_assert(CastFrom<unsigned char>(AllOnes) == 0xFF, "");
static_assert(CastFrom<long>(AllOnes) == -1, "");
static_assert(CastFrom<unsigned short>(AllOnes) == 0xFFFF, "");
static_assert(CastFrom<int>(AllOnes) == -1, "");
static_assert(CastFrom<int128_t>(AllOnes) == -1, "");
static_assert(CastFrom<uint128_t>(AllOnes) == AllOnes, "");

template <typename T>
constexpr __int128 CastTo(T A) {
int128_t B = (int128_t)A;
Expand Down