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Fixes for sanitizer errors from SPEC CPU testing #7697

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Fixes for sanitizer errors from SPEC CPU testing #7697

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05bac66
Sanitizer fix: shift exponent too large
heshpdx Jul 23, 2025
3410738
Sanitizer fix: overflow in std::abs
heshpdx Jul 23, 2025
6f70d59
Sanitizer fix: signed integer overflow
heshpdx Jul 23, 2025
6c02e8d
Change long long to MathLib::bigint
heshpdx Jul 23, 2025
2f95d90
Change remaining long long to MathLib::bigint
heshpdx Jul 24, 2025
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26 changes: 20 additions & 6 deletions lib/infer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -127,8 +127,12 @@ namespace {
Interval result;
const ValueFlow::Value* minValue = getCompareValue(values, predicate, std::less<MathLib::bigint>{});
if (minValue) {
if (minValue->isImpossible() && minValue->bound == ValueFlow::Value::Bound::Upper)
result.setMinValue(minValue->intvalue + 1, minValue);
if (minValue->isImpossible() && minValue->bound == ValueFlow::Value::Bound::Upper) {
if (std::numeric_limits<MathLib::bigint>::max() == minValue->intvalue)
result.setMinValue(minValue->intvalue, minValue);
else
result.setMinValue(minValue->intvalue + 1, minValue);
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I wonder if not doing the addition still leads to a useful value, or if we should bail out somehow for LLONG_MAX.

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@pfultz2 Maybe you have some insights?

}
if (minValue->isPossible() && minValue->bound == ValueFlow::Value::Bound::Lower)
result.setMinValue(minValue->intvalue, minValue);
if (!minValue->isImpossible() && (minValue->bound == ValueFlow::Value::Bound::Point || minValue->isKnown()) &&
Expand All @@ -137,8 +141,12 @@ namespace {
}
const ValueFlow::Value* maxValue = getCompareValue(values, predicate, std::greater<MathLib::bigint>{});
if (maxValue) {
if (maxValue->isImpossible() && maxValue->bound == ValueFlow::Value::Bound::Lower)
result.setMaxValue(maxValue->intvalue - 1, maxValue);
if (maxValue->isImpossible() && maxValue->bound == ValueFlow::Value::Bound::Lower) {
if (std::numeric_limits<MathLib::bigint>::min() == maxValue->intvalue)
result.setMaxValue(minValue->intvalue, maxValue);
else
result.setMaxValue(maxValue->intvalue - 1, maxValue);
}
if (maxValue->isPossible() && maxValue->bound == ValueFlow::Value::Bound::Upper)
result.setMaxValue(maxValue->intvalue, maxValue);
assert(!maxValue->isKnown());
Expand Down Expand Up @@ -312,14 +320,20 @@ std::vector<ValueFlow::Value> infer(const ValuePtr<InferModel>& model,
result.push_back(std::move(value));
} else {
if (!diff.minvalue.empty()) {
ValueFlow::Value value(diff.minvalue.front() - 1);
int adder(0);
if (std::numeric_limits<MathLib::bigint>::min() < diff.minvalue.front())
adder = -1;
ValueFlow::Value value(diff.minvalue.front() + adder);
value.setImpossible();
value.bound = ValueFlow::Value::Bound::Upper;
addToErrorPath(value, diff.minRef);
result.push_back(std::move(value));
}
if (!diff.maxvalue.empty()) {
ValueFlow::Value value(diff.maxvalue.front() + 1);
int adder(0);
if (std::numeric_limits<MathLib::bigint>::max() > diff.maxvalue.front())
adder = 1;
ValueFlow::Value value(diff.maxvalue.front() + adder);
value.setImpossible();
value.bound = ValueFlow::Value::Bound::Lower;
addToErrorPath(value, diff.maxRef);
Expand Down
6 changes: 5 additions & 1 deletion lib/token.cpp
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Expand Up @@ -2015,7 +2015,11 @@ static bool isAdjacent(const ValueFlow::Value& x, const ValueFlow::Value& y)
return true;
if (x.valueType == ValueFlow::Value::ValueType::FLOAT)
return false;
return std::abs(x.intvalue - y.intvalue) == 1;

// original abs() is not safe against overflows:
// return std::abs(x.intvalue - y.intvalue) == 1;
return (y.intvalue != std::numeric_limits<MathLib::bigint>::max() && x.intvalue == y.intvalue + 1) ||
(y.intvalue != std::numeric_limits<MathLib::bigint>::min() && x.intvalue == y.intvalue - 1);
}

static bool removePointValue(std::list<ValueFlow::Value>& values, std::list<ValueFlow::Value>::iterator& x)
Expand Down
4 changes: 4 additions & 0 deletions lib/vf_common.cpp
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Expand Up @@ -38,6 +38,7 @@
#include <limits>
#include <utility>
#include <vector>
#include <algorithm>

namespace ValueFlow
{
Expand Down Expand Up @@ -101,6 +102,9 @@ namespace ValueFlow
if (value_size == 0)
return value;

// sizeof(long long) = 8
value_size = std::min(sizeof(MathLib::bigint), value_size);
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I have the feeling we want to be able to truncate according to sizeof(int) here. I.e. the result of ~0U + 2U should be 1.


const MathLib::biguint unsignedMaxValue = std::numeric_limits<MathLib::biguint>::max() >> ((sizeof(unsignedMaxValue) - value_size) * 8);
const MathLib::biguint signBit = 1ULL << (value_size * 8 - 1);
value &= unsignedMaxValue;
Expand Down