This PR adds short-circuit support to bv_decide to accelerate
multiplications with shared coefficients. In particular, `a * x = b * x`
can be extended to `a = b v (a * x = b * x)`. The latter is faster if `a
= b` is true, as `a = b` may be evaluated without considering the
multiplication circuit. On the other hand, we require the multiplication
circuit, as `a * x = b * x -> a = b` is not always true due to two's
complement wrapping.
We support multiplications through acNF, which takes into account shared
terms across equality canonicalizing `a * (b * c1) = a * (b * c2)` to
`(a * b) * c1 = (a * b) * c2`. As a result, the non-shared terms are
lifted to the top such that canonical rewrites for binary multiplication
with shared terms on the left/right are sufficient.
We add an option `bv_decide +shortCircuit` which controls this feature
(currently disabled by default).
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Co-authored-by: Siddharth Bhat <siddu.druid@gmail.com>
Co-authored-by: Henrik Böving <hargonix@gmail.com>
