Re: checking against signed integer overflow

[Bruno Haible]

Paul Eggert wrote:
> The Gnulib intprops module doesn't use asms and does not rely on undefined 
> behavior,
> and I'd be surprised if it's significantly outperformed by the usual asms for
> this particular task.

Yes. Already in 1999 I made the experience that, for a function that contained
lots of integer multiplications (*), GCC (must have been egcs at that time)
produced code that outperformed my hand-written assembly code by a few percent.
And nowadays GCC does even more optimizations than 21 years ago.

Bruno

(*) The function did a Montgomery multiplication mod p, where p > 2^128; this
is the workhorse of the arithmetic on an elliptic curve.