[Optimization] Detuple branch results

[NinoFloris]

https://sharplab.io/#v2:DYLgZgzgPg9gDgUwHYAIDKBPCAXBBbAWAChjjgFsUAPACgEoUBeYlVlcyjFeplAZlJE27CtwCGAGgBGDRihZsFw1gEswKACJjcAFRV4EAOgByMAO6GtXAHwoAjCmwALZPKHKPGehJQAmJcoIwBAIbh4evj5edILCYigA1ChSQA==

open System

let x() =
    let y () = 3

    let (a,b) =     
        if DateTime.Now.Day > 1 then 
            y(), 2
        else 
            2, y()

    a + b

I would expect a direct tuple/detuple in a binding, like the above, to be rewritten to mutable a and b mutated directly from their branches.

In cases where detupling is successful (example of a case below) the entire function compiles down to the result of a + b.

let x() =
    let y () = 3

    let (a,b) = 
        y(), 2
    
    a + b

Related:
dotnet/coreclr#21950

[kerams]

This is done and can be closed.