[#llvm-isImpliedCondition-0c]
= xref:llvm.adoc[llvm]::isImpliedCondition
:relfileprefix: ../
:mrdocs:

Return whether RHS is implied true or false by LHS, if known.

== Synopsis

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

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
std::optional<bool>
isImpliedCondition(
    xref:llvm/Value.adoc[Value] const* LHS,
    xref:llvm/Value.adoc[Value] const* RHS,
    xref:llvm/DataLayout.adoc[DataLayout] const& DL,
    bool LHSIsTrue = true,
    unsigned int Depth = 0);
----

== Description

Return true if RHS is known to be implied true by LHS. Return false if RHS is known to be implied false by LHS. Otherwise, return std::nullopt if no implication can be made. A & B must be i1 (boolean) values or a vector of such values. Note that the truth table for implication is the same as <=u on i1 values (but not <=s!). The truth table for both is: | T | F (B) T | T | F F | T | T (A)

== Return Value

True/false if implied, or nullopt if unknown.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *LHS*
| Condition assumed true or false according to `LHSIsTrue.`
| *RHS*
| Condition whose implication from `LHS` is tested.
| *DL*
| Data layout used by the implication analysis.
| *LHSIsTrue*
| Whether `LHS` is assumed true (vs false).
| *Depth*
| Current recursion depth for this query.
|===


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