I don't think I understand what you are saying. Anyway, if you are strapped for space, do not use a winner tree.

Ah, I meant that for a classic heap, it's convenient to assign h[0] to the limit of your goal function (e.g. -inf for a min heap) cause that way you can skip the while i>0 check and just do while h[i>>1] > min(h[i], h[i+1]), asserting that the condition is definitely false when i < 2

I guess that it's not as important when you're explicitly willing to pay the piper and run the full log2n iterations just for the sake of branch predictability.

Thanks for the algo though, before today I never would've thought about doing a branchless downheap with i = i<<1 + h[i<<1] != h[i]