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

Return the preheader block for this loop, or null if there is none.

== Synopsis

Declared in `<llvm/Support/GenericLoopInfo.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
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xref:llvm/BasicBlock.adoc[BasicBlock]*
getLoopPreheader() const;
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== Description

A loop has a preheader if there is only one edge to the header of the loop from outside of the loop and it is legal to hoist instructions into the predecessor. If this is the case, the block branching to the header of the loop is the preheader node.

== Return Value

The preheader block, or null if there is none.


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