[#llvm-RecurrenceDescriptor-2constructor-05]
= xref:llvm.adoc[llvm]::xref:llvm/RecurrenceDescriptor.adoc[RecurrenceDescriptor]::RecurrenceDescriptor
:relfileprefix: ../../
:mrdocs:

Construct a recurrence descriptor with full reduction metadata.

== Synopsis

Declared in `<llvm/Analysis/IVDescriptors.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
RecurrenceDescriptor(
    xref:llvm/Value.adoc[Value]* Start,
    xref:llvm/Instruction.adoc[Instruction]* Exit,
    xref:llvm/StoreInst.adoc[StoreInst]* Store,
    xref:llvm/RecurKind.adoc[RecurKind] K,
    xref:llvm/FastMathFlags.adoc[FastMathFlags] FMF,
    xref:llvm/Instruction.adoc[Instruction]* ExactFP,
    xref:llvm/Type.adoc[Type]* RT,
    bool Signed,
    bool Ordered,
    xref:llvm/SmallPtrSetImpl-05.adoc[SmallPtrSetImpl<Instruction*>]& CI,
    unsigned int MinWidthCastToRecurTy,
    bool PhiHasUsesOutsideReductionChain = false);
----

== Parameters

[cols="1,4"]
|===
| Name| Description
| *Start*
| Starting value of the recurrence.
| *Exit*
| Instruction whose value is used outside the loop.
| *Store*
| Optional store of a reduction result to an invariant address.
| *K*
| Kind of recurrence represented by this descriptor.
| *FMF*
| Fast‐math flags on the recurrent instructions.
| *ExactFP*
| First non‐reassociative FP instruction in the use‐chain.
| *RT*
| Type of the recurrence, possibly narrower than the PHI type.
| *Signed*
| True if all source operands are SExtInsts.
| *Ordered*
| True if this recurrence can be treated as in‐order.
| *CI*
| Instructions used for type‐promoting the recurrence.
| *MinWidthCastToRecurTy*
| Minimum bit width used by the recurrence.
| *PhiHasUsesOutsideReductionChain*
| True if the PHI has uses outside the reduction chain.
|===


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