See https://github.com/morelinq/MoreLINQ/pull/582/files#r470967212

OptupleCost.cs

using System;

public class C {
    public void M((bool, object) x) {
        if (x is (true, {} obj)) {
            Console.WriteLine(obj);
        }
    }
    public void N(bool f, object obj) {
        if (f) {
            Console.WriteLine(obj);
        }
    }
}

OptupleCost.jit.asm

; Core CLR v4.700.20.26901 on amd64

C..ctor()
    L0000: ret

C.M(System.ValueTuple`2<Boolean,System.Object>)
    L0000: cmp byte ptr [rdx+8], 0
    L0004: je short L001b
    L0006: mov rcx, [rdx]
    L0009: test rcx, rcx
    L000c: je short L001b
    L000e: mov rax, System.Console.WriteLine(System.Object)
    L0018: jmp rax
    L001b: ret

C.N(Boolean, System.Object)
    L0000: test dl, dl
    L0002: je short L0014
    L0004: mov rcx, r8
    L0007: mov rax, System.Console.WriteLine(System.Object)
    L0011: jmp rax
    L0014: ret

​​.sharplab.json

{
    "version": 1,
    "target": "JIT ASM",
    "mode": "Release",
    "branch": "core-x64"
}