On Mon, Feb 13, 2017 at 12:38:47PM -0800, Junio C Hamano wrote: > Jeff King <peff@xxxxxxxx> writes: > > > I wonder if xmalloc() should be the one doing the saved_errno trick. > > After all, it has only two outcomes: we successfully allocated the > > memory, or we called die(). > > I would be lying if I said I did not considered it when I wrote the > message you are responding to, but I rejected it because that would > be optimizing for a wrong case, in that most callers of xmalloc() > and friends do not do so in the error codepath, and we would be > penalizing them by doing the saved_errno dance unconditionally. Yes, that also occurred to me. I'm not sure if two integer swaps is enough to care about when compared to the cost of a malloc(), though. IOW, I think this may be a case where we should be optimizing for programmer time (fewer lines of code, and one less thing to worry about in the callers) versus squeezing out every instruction. -Peff