bug[next]: Respect evaluation order in InlineCenterDerefLiftVars

[tehrengruber]

Changes the InlineCenterDerefLiftVars pass to respect evaluation order by lazily evaluating the inlined values.

Consider the following case that is common in boundary conditions:

let(var, (↑deref)(it2))(if ·on_bc then 0 else ·var)

Then var should only be dereferenced in case ·on_bc evalutes to False. Previously we just evaluated all values unconditionally:

let(_icdlv_1, ·it)(if ·on_bc then 0 else _icdlv_1)

Now we instead create a 0-ary lambda function for _icdlv_1 and evaluate it when the value is needed.

let(_icdlv_1, λ() → ·it)(if ·on_bc then 0 else _icdlv_1())

Note that as a result we do evaluate the function multiple times. To avoid redundant recompuations usage of the common subexpression elimination is required.

[havogt]

Can you replace bc by something like: conditionally evaluate?