LiftImpure

The corresponding lifter for pass-by-name arguments

Lift out function prefix and all arguments from application

pre.f(arg1, ..., argN) becomes

val x0 = pre val x1 = arg1 ... val xN = argN x0.f(x1, ..., xN)

But leave pure expressions alone.

Lift arguments that are not-idempotent into ValDefs in buffer defs and replace by the idents of so created ValDefs.

Lift out common part of lhs tree taking part in an operator assignment such as

lhs += expr

The tree of a lifted definition

The flags of a lifted definition

Test indicating expr does not need lifting