[#llvm-simplifyLoop]
= xref:llvm.adoc[llvm]::simplifyLoop
:relfileprefix: ../
:mrdocs:

Simplify each loop in a loop nest recursively.

== Synopsis

Declared in `<llvm/Transforms/Utils/LoopSimplify.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
bool
simplifyLoop(
    xref:llvm/Loop.adoc[Loop]* L,
    xref:llvm/DominatorTree.adoc[DominatorTree]* DT,
    xref:llvm/LoopInfo.adoc[LoopInfo]* LI,
    xref:llvm/ScalarEvolution.adoc[ScalarEvolution]* SE,
    xref:llvm/AssumptionCache.adoc[AssumptionCache]* AC,
    xref:llvm/MemorySSAUpdater.adoc[MemorySSAUpdater]* MSSAU,
    bool PreserveLCSSA);
----

== Description

This takes a potentially un‐simplified loop L (and its children) and turns it into a simplified loop nest with preheaders and single backedges. It will update `DominatorTree,` `LoopInfo,` `ScalarEvolution` and `MemorySSA` analyses if they're non‐null, and LCSSA if `PreserveLCSSA` is true.

== Return Value

True if any modifications were made to the loop nest.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *L*
| The loop (and its children) to simplify.
| *DT*
| Optional DominatorTree to update, or nullptr.
| *LI*
| Optional LoopInfo to update, or nullptr.
| *SE*
| Optional ScalarEvolution to update, or nullptr.
| *AC*
| Optional AssumptionCache used during simplification, or nullptr.
| *MSSAU*
| Optional MemorySSA updater, or nullptr.
| *PreserveLCSSA*
| When true, preserve LCSSA form.
|===


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