https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89120
--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> --- First there is the issue of iterator vs value, as in your other PR. The performance of minmax depends a lot on the element type and the distribution. The standard requires that we perform only 3n/2 comparisons (not 2n like your version), which essentially prescribes the implementation. However, minmax is probably the most classical example shown in classes on branch prediction. For a uniform choice of a permutation, the 2n comparisons can be well predicted (O(log n) are mispredicted) while if you only do 3n/2 comparisons, n/2 of those are unpredictable, so n/4 are badly predicted, and that costs a lot.
