https://github.com/dotnet/csharplang/issues/697

output.asm

; Assembly listing for method jitdumpapp.Program:Today(ref):ref
; Emitting BLENDED_CODE for X64 CPU with SSE2
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  6,  6   )     ref  ->  rcx         class-hnd
;  V01 loc0         [V01,T01] (  3,  3   )     ref  ->  rax         ld-addr-op class-hnd
;* V02 loc1         [V02    ] (  0,  0   )     ref  ->  zero-ref    ld-addr-op class-hnd
;# V03 OutArgs      [V03    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]
;
; Lcl frame size = 0

G_M2442_IG01:

G_M2442_IG02:
       8B01                 mov      eax, dword ptr [rcx]
       488B4108             mov      rax, gword ptr [rcx+8]

G_M2442_IG03:
       C3                   ret

; Total bytes of code 7, prolog size 0 for method jitdumpapp.Program:Today(ref):ref
; ============================================================
; Assembly listing for method jitdumpapp.Program:Tomorrow(ref):ref
; Emitting BLENDED_CODE for X64 CPU with SSE2
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  3,  3   )     ref  ->  rcx         class-hnd
;# V01 OutArgs      [V01    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]
;
; Lcl frame size = 0

G_M38658_IG01:

G_M38658_IG02:
       488B4108             mov      rax, gword ptr [rcx+8]

G_M38658_IG03:
       C3                   ret

; Total bytes of code 5, prolog size 0 for method jitdumpapp.Program:Tomorrow(ref):ref
; ============================================================

Program.cs

using System;
using System.Runtime.CompilerServices;

class Program
{
    static void Main()
    {
        var c = new C();
        Today(c);
        Tomorrow(c);
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    static string Today(C e)
    {
        var (x, _) = e;
        return x;
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    static string Tomorrow(C e)
    {
        var x = e.Foo;
        return x;
    }
}

class C
{
    public string Foo { get; }
    public string Bar { get; }

    public void Deconstruct(out string foo, out string bar)
    {
        foo = this.Foo;
        bar = this.Bar;
    }
}