[PATCH] D15385: [Support] Add saturating multiply-add support function

[David Li via llvm-commits]

davidxl added inline comments.

================
Comment at: include/llvm/Support/MathExtras.h:727
@@ +726,3 @@
+typename std::enable_if<std::is_unsigned<T>::value, T>::type
+SaturatingMultiplyAdd(T X, T Y, T A, bool *ResultOverflowed = nullptr) {
+  bool Dummy;
----------------
Do we want types of X and Y to be same ? For instance, the weight can be less than 1.

Also we may want to have an overloaded function that is used for common cases where one of the X or Y is constant:

template <typename T, uint64_t Multiplier>
	​typename std::enable_if<std::is_unsigned<T>::value, T>::type   		​       SaturatingMultiplyAdd(T X, T A, bool *ResultOverflowed = nullptr) {
 ...
}

it is probably just slightly more efficient so probably not in this patch.


http://reviews.llvm.org/D15385