Import Upstream version 20180207

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

LoopInvariant
=============

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

== Description ==

This pass removes loop invariant arguments to local loops.

----
  loop (x, y)
    ...
  ...
    loop (x, z)
  ...
----

becomes

----
  loop' (x, y)
    loop (y)
  loop (y)
    ...
  ...
    loop (z)
  ...
----

== Implementation ==

* <!ViewGitFile(mlton,master,mlton/ssa/loop-invariant.fun)>

== Details and Notes ==

{empty}