ggml-org/llama.cpp b12128

on GitHub

tests: fix CI flakes of TOPK_MOE caused by near ties (#31426)

• tests: fix CI flakes of TOPK_MOE caused by near ties

With uniform random logits, two experts sometimes land within one f32
ulp of each other at a routing boundary, mostly with sqrt_softplus
gating whose output range is narrow. A backend whose gating differs by
a few ulps from the CPU then picks the other expert and the test fails.

Draw each row of logits again until the group selection and the final
top-k both have a relative margin of 1e-4, computed on the host in
double precision.

• tests: build the TOPK_MOE logits by inverting the gating function

Draw the selection scores (probs plus bias) of each row as a random
permutation of a grid, move the experts of the best groups up by half a
step, and set the logits to the inverse of the gating function at these
scores. Every expert and group decision is then one grid step apart on
all backends, and the host no longer recomputes the routing.

The softmax probs are built to sum to one so that the softmax keeps the
scores, and the views of the logits are not initialized again after the
logits are set.