I'm curious as to why binaryen doesn't implement an optimization pass for tailcall feature. Is the optimization itself not feasible?

If it is feasible, I would like to implement it.

The basic idea is we can convert

(func ...
   (call $f)
)

to

(func ...
   (return_call $f)
)

(func ...
   (return (call $f))
)

to

(func ...
   (return_call $f)
)

(func ...
   (if
      (condition)
      (call $f)
   )
)

to

(func ...
   (if
      (condition)
      (return_call $f)
   )
)