What's the benefit of taking "do" blocks apart? Is there a way to turn that off?

[Erdi, Gergo]

PUBLIC

Hi,

I'm seeing 'do' blocks getting taking apart into top-level definitions, so e.g.

main = do
  some complicated expression 1
  some complicated expression 2

is compiled into

sat_sKv = some complicated expression 1
sat_sKw = \_ -> some complicated expression 2
main = bindIO sat_sKv sat_sKw

This seems to happen regardless of any common subexpressions, i.e. it is not the case that sat_sKv or sat_sKw are used anywhere else.

What is the intended benefit of this floating-out? Is there a particular Core-to-Core pass that causes this? Is it possible to turn it off?

Thanks,
            Gergo

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