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cxxrtl: Fix sdivmod 

x = x.neg(); results in the subsequent x.is_neg() always being false.
Ditto for the dividend.is_neg() != divisor.is_neg() test.
This commit is contained in:
Merry 2024-03-29 20:53:26 +00:00 committed by Catherine
parent 0a854cf4ce
commit d07a55a852
2 changed files with 109 additions and 4 deletions
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8
backends/cxxrtl/runtime/cxxrtl/cxxrtl.h
View File

@ -625,11 +625,11 @@ struct value : public expr_base<value<Bits>> {
value<Bits + 1> remainder;
value<Bits + 1> dividend = sext<Bits + 1>();
value<Bits + 1> divisor = other.template sext<Bits + 1>();
if (dividend.is_neg()) dividend = dividend.neg();
if (divisor.is_neg()) divisor = divisor.neg();
if (is_neg()) dividend = dividend.neg();
if (other.is_neg()) divisor = divisor.neg();
std::tie(quotient, remainder) = dividend.udivmod(divisor);
if (dividend.is_neg() != divisor.is_neg()) quotient = quotient.neg();
if (dividend.is_neg()) remainder = remainder.neg();
if (is_neg() != other.is_neg()) quotient = quotient.neg();
if (is_neg()) remainder = remainder.neg();
return {quotient.template trunc<Bits>(), remainder.template trunc<Bits>()};
}
};

105
tests/cxxrtl/test_value_fuzz.cc
View File

@ -25,6 +25,11 @@ T rand_int(T min = std::numeric_limits<T>::min(), T max = std::numeric_limits<T>
return dist(generator);
}
int64_t sext(size_t bits, uint64_t value)
{
return (int64_t)(value << (64 - bits)) >> (64 - bits);
}
struct BinaryOperationBase
{
void tweak_input(uint64_t &a, uint64_t &b) {}
@ -246,6 +251,106 @@ struct CtlzTest
}
} ctlz;
struct UdivTest : BinaryOperationBase
{
UdivTest()
{
std::printf("Randomized tests for value::udivmod (div):\n");
test_binary_operation(*this);
}
uint64_t reference_impl(size_t bits, uint64_t a, uint64_t b)
{
return a / b;
}
template<size_t Bits>
cxxrtl::value<Bits> testing_impl(cxxrtl::value<Bits> a, cxxrtl::value<Bits> b)
{
return std::get<0>(a.udivmod(b));
}
void tweak_input(uint64_t &, uint64_t &b)
{
if (b == 0) b = 1; // Avoid divide by zero
}
} udiv;
struct UmodTest : BinaryOperationBase
{
UmodTest()
{
std::printf("Randomized tests for value::udivmod (mod):\n");
test_binary_operation(*this);
}
uint64_t reference_impl(size_t bits, uint64_t a, uint64_t b)
{
return a % b;
}
template<size_t Bits>
cxxrtl::value<Bits> testing_impl(cxxrtl::value<Bits> a, cxxrtl::value<Bits> b)
{
return std::get<1>(a.udivmod(b));
}
void tweak_input(uint64_t &, uint64_t &b)
{
if (b == 0) b = 1; // Avoid divide by zero
}
} umod;
struct SdivTest : BinaryOperationBase
{
SdivTest()
{
std::printf("Randomized tests for value::sdivmod (div):\n");
test_binary_operation(*this);
}
uint64_t reference_impl(size_t bits, uint64_t a, uint64_t b)
{
return (uint64_t)(sext(bits, a) / sext(bits, b));
}
template<size_t Bits>
cxxrtl::value<Bits> testing_impl(cxxrtl::value<Bits> a, cxxrtl::value<Bits> b)
{
return std::get<0>(a.sdivmod(b));
}
void tweak_input(uint64_t &, uint64_t &b)
{
if (b == 0) b = 1; // Avoid divide by zero
}
} sdiv;
struct SmodTest : BinaryOperationBase
{
SmodTest()
{
std::printf("Randomized tests for value::sdivmod (mod):\n");
test_binary_operation(*this);
}
uint64_t reference_impl(size_t bits, uint64_t a, uint64_t b)
{
return (uint64_t)(sext(bits, a) % sext(bits, b));
}
template<size_t Bits>
cxxrtl::value<Bits> testing_impl(cxxrtl::value<Bits> a, cxxrtl::value<Bits> b)
{
return std::get<1>(a.sdivmod(b));
}
void tweak_input(uint64_t &, uint64_t &b)
{
if (b == 0) b = 1; // Avoid divide by zero
}
} smod;
int main()
{
}