/// Sample counts accumulate using saturating arithmetic, to avoid wrapping
/// around unsigned integers.
void addSamples(uint64_t S) {
- NumSamples = SaturatingAdd(NumSamples, S);
+ if (NumSamples <= std::numeric_limits<uint64_t>::max() - S)
+ NumSamples += S;
+ else
+ NumSamples = std::numeric_limits<uint64_t>::max();
}
/// Add called function \p F with samples \p S.
/// around unsigned integers.
void addCalledTarget(StringRef F, uint64_t S) {
uint64_t &TargetSamples = CallTargets[F];
- TargetSamples = SaturatingAdd(TargetSamples, S);
+ if (TargetSamples <= std::numeric_limits<uint64_t>::max() - S)
+ TargetSamples += S;
+ else
+ TargetSamples = std::numeric_limits<uint64_t>::max();
}
/// Return true if this sample record contains function calls.
return int64_t(X << (64 - B)) >> (64 - B);
}
-/// \brief Add two unsigned integers, X and Y, of type T.
-/// Clamp the result to the maximum representable value of T on overflow.
-template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, T>::type
-SaturatingAdd(T X, T Y) {
- // Hacker's Delight, p. 29
- T Z = X + Y;
- if (Z < X || Z < Y)
- return std::numeric_limits<T>::max();
- else
- return Z;
-}
-
-/// \brief Multiply two unsigned integers, X and Y, of type T.
-/// Clamp the result to the maximum representable value of T on overflow.
-template <typename T>
-typename std::enable_if<std::is_unsigned<T>::value, T>::type
-SaturatingMultiply(T X, T Y) {
- // Hacker's Delight, p. 30
- T Z = X * Y;
- if (Y != 0 && Z / Y != X)
- return std::numeric_limits<T>::max();
- else
- return Z;
-}
-
extern const float huge_valf;
} // End llvm namespace
EXPECT_EQ(552u, RoundUpToAlignment(321, 255, 42));
}
-template<typename T>
-void SaturatingAddTestHelper()
-{
- EXPECT_EQ(static_cast<T>(3),
- SaturatingAdd(static_cast<T>(1), static_cast<T>(2)));
- EXPECT_EQ(std::numeric_limits<T>::max(),
- SaturatingAdd(std::numeric_limits<T>::max(), static_cast<T>(1)));
- EXPECT_EQ(std::numeric_limits<T>::max(),
- SaturatingAdd(static_cast<T>(1), std::numeric_limits<T>::max()));
- EXPECT_EQ(std::numeric_limits<T>::max(),
- SaturatingAdd(std::numeric_limits<T>::max(),
- std::numeric_limits<T>::max()));
-}
-
-TEST(MathExtras, SaturatingAdd) {
- SaturatingAddTestHelper<uint8_t>();
- SaturatingAddTestHelper<uint16_t>();
- SaturatingAddTestHelper<uint32_t>();
- SaturatingAddTestHelper<uint64_t>();
-}
-
-template<typename T>
-void SaturatingMultiplyTestHelper()
-{
- EXPECT_EQ(static_cast<T>(0),
- SaturatingMultiply(static_cast<T>(1), static_cast<T>(0)));
- EXPECT_EQ(static_cast<T>(0),
- SaturatingMultiply(static_cast<T>(0), static_cast<T>(1)));
- EXPECT_EQ(static_cast<T>(6),
- SaturatingMultiply(static_cast<T>(2), static_cast<T>(3)));
- EXPECT_EQ(std::numeric_limits<T>::max(),
- SaturatingMultiply(std::numeric_limits<T>::max(),
- static_cast<T>(2)));
- EXPECT_EQ(std::numeric_limits<T>::max(),
- SaturatingMultiply(static_cast<T>(2),
- std::numeric_limits<T>::max()));
- EXPECT_EQ(std::numeric_limits<T>::max(),
- SaturatingMultiply(std::numeric_limits<T>::max(),
- std::numeric_limits<T>::max()));
-}
-
-TEST(MathExtras, SaturatingMultiply) {
- SaturatingMultiplyTestHelper<uint8_t>();
- SaturatingMultiplyTestHelper<uint16_t>();
- SaturatingMultiplyTestHelper<uint32_t>();
- SaturatingMultiplyTestHelper<uint64_t>();
-}
-
}