Import Upstream version 20180207

[hcoop/debian/mlton.git] / doc / guide / src / IntroduceLoops.adoc

IntroduceLoops
==============

<:IntroduceLoops:> is an optimization pass for the <:SSA:>
<:IntermediateLanguage:>, invoked from <:SSASimplify:>.

== Description ==

This pass rewrites any <:SSA:> function that calls itself in tail
position into one with a local loop and no self tail calls.

A <:SSA:> function like
----
fun F (arg_0, arg_1) = L_0 ()
  ...
  L_16 (x_0)
    ...
    F (z_0, z_1) Tail
  ...
----
becomes
----
fun F (arg_0', arg_1') = loopS_0 ()
  loopS_0 ()
    loop_0 (arg_0', arg_1')
  loop_0 (arg_0, arg_1)
    L_0 ()
  ...
  L_16 (x_0)
    ...
    loop_0 (z_0, z_1)
  ...
----

== Implementation ==

* <!ViewGitFile(mlton,master,mlton/ssa/introduce-loops.fun)>

== Details and Notes ==

{empty}