Llir Builder for HKMC2

[waterlens]

No description provided.

[LPTK]

It looks like the CI failed for the same reason as in #257 (comment)

[LPTK]

This looks mostly good, but I found some worrying cases. Sometimes the LLIR generates references to parameter names from outside the join point:

:sllir
:scpp
let x = 10
if true do
  set x += 1
x
//│ = 11
//│ x = 11
//│ LLIR:
//│   
//│   def j$0(x$2) =
//│     x$2
//│   let x$0 = 10 in
//│   let x$1 = true in
//│   case x$1 of
//│     BoolLit(true) =>
//│       let x$3 = +(x$2,1) in
//│       let x$4 = undefined in
//│       jump j$0(x$3)
//│     _ =>
//│       let x$5 = undefined in
//│       jump j$0(x$2)

If you don't want to support mutation, it's fine, but then you should cleanly abort compilation.

But the fact that it generates a reference to a parameter that's not in scope also hints at a deeper logic problem in the IR builder, which should probably be fixed as well.

[LPTK]

LGTM!