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

Fold away single‐entry PHI nodes in a block with one predecessor.

== Synopsis

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

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
bool
FoldSingleEntryPHINodes(
    xref:llvm/BasicBlock.adoc[BasicBlock]* BB,
    xref:llvm/MemoryDependenceResults.adoc[MemoryDependenceResults]* MemDep = nullptr);
----

== Description

We know that BB has one predecessor. If there are any single‐entry PHI nodes in it, fold them away. This handles the case when all entries to the PHI nodes in a block are guaranteed equal, such as when the block has exactly one predecessor.

== Return Value

True if any single‐entry PHI nodes were folded away.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *BB*
| Block whose single‐entry PHIs may be folded.
| *MemDep*
| Optional memory‐dependence results to update.
|===


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