Previously we used the existing `Polynomial::rotate` and
`EvaluationDomain::rotate_extended` APIs to rotate the polynomials we
query at non-zero rotations, and then stored references to the chunks of
each (rotated and unrotated) polynomial as slices. When we reached an
`AstLeaf`, we would then clone the corresponding polynomial chunk.
We now avoid all of this with combined "rotate-and-chunk" APIs, making
use of the observation that a rotation is simply a renumbering of the
indices of the polynomial coefficients. Given that when we reach an
`AstLeaf` we already needed to allocate, these new APIs have the same
number of allocations during AST evaluation, but enable us to completely
avoid caching any information about the rotations or rotated polynomials
ahead of time.
Jack Grigg
Daira Hopwood
parazyd