ThrowHelper

ThrowHelper_code.cs

using System;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

namespace ConsoleApplication
{
    public unsafe class Program
    {
        public static void Main(string[] args)
        {
            Sample sample = new Sample();
            Console.WriteLine(A(sample));
            Console.WriteLine(B(sample));
            Console.WriteLine(C(sample));
            Console.WriteLine(D(sample));
            Console.WriteLine(E(sample));
        }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static int A(Sample sample)
        {
            if (sample == null) ThrowHelper.ThrowArgumentNull();

            return sample.A;
        }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static int B(Sample sample)
        {
            if (sample == null) ThrowHelper.ThrowArgumentNull1();

            return sample.A;
        }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static int C(Sample sample)
        {
            if (sample == null) ThrowArgumentNull();

            return sample.A;
        }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static int D(Sample sample)
        {
            ThrowHelper.ThrowIfArgumentNull(sample);

            return sample.A;
        }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static int E(Sample sample)
        {
            ThrowHelper.ThrowIfArgumentNull1(sample);

            return sample.A;
        }

        private static void ThrowArgumentNull() => throw new ArgumentNullException("argument");
    }

    public class Sample
    {
        public int A { get; set; } = 42;
    }

    internal static class ThrowHelper
    {
        public static void ThrowArgumentNull() => throw CreateArgumentNull();
        [MethodImpl(MethodImplOptions.NoInlining)]
        private static Exception CreateArgumentNull() => new ArgumentNullException("argument");

        public static void ThrowArgumentNull1() => throw new ArgumentNullException("argument");

        public static void ThrowIfArgumentNull<T>(T arg) where T : class
        {
            if (arg == null)
                throw new ArgumentNullException("argument");
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void ThrowIfArgumentNull1<T>(T arg) where T : class
        {
            if (arg == null)
                throw new ArgumentNullException("argument");
        }
    }
}

ThrowHelper_dasm.asm

42
42
42
42
; Assembly listing for method ConsoleApplication.Program:A(ref):int
; Emitting BLENDED_CODE for X64 CPU with AVX
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  5,  5   )     ref  ->  rdi         class-hnd
;# V01 OutArgs      [V01    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]  
;
; Lcl frame size = 8

G_M64832_IG01:
       50                   push     rax

G_M64832_IG02:
       4885FF               test     rdi, rdi
       7408                 je       SHORT G_M64832_IG05

G_M64832_IG03:
       8B4708               mov      eax, dword ptr [rdi+8]

G_M64832_IG04:
       4883C408             add      rsp, 8
       C3                   ret      

G_M64832_IG05:
       E8E5FBFFFF           call     ConsoleApplication.ThrowHelper:ThrowArgumentNull()
       CC                   int3     

; Total bytes of code 20, prolog size 1 for method ConsoleApplication.Program:A(ref):int
; ============================================================
; Assembly listing for method ConsoleApplication.Program:B(ref):int
; Emitting BLENDED_CODE for X64 CPU with AVX
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  5,  5   )     ref  ->  rdi         class-hnd
;# V01 OutArgs      [V01    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]  
;
; Lcl frame size = 8

G_M64831_IG01:
       50                   push     rax

G_M64831_IG02:
       4885FF               test     rdi, rdi
       7408                 je       SHORT G_M64831_IG05

G_M64831_IG03:
       8B4708               mov      eax, dword ptr [rdi+8]

G_M64831_IG04:
       4883C408             add      rsp, 8
       C3                   ret      

G_M64831_IG05:
       E885E7FFFF           call     ConsoleApplication.ThrowHelper:ThrowArgumentNull1()
       CC                   int3     

; Total bytes of code 20, prolog size 1 for method ConsoleApplication.Program:B(ref):int
; ============================================================
; Assembly listing for method ConsoleApplication.Program:C(ref):int
; Emitting BLENDED_CODE for X64 CPU with AVX
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  5,  5   )     ref  ->  rdi         class-hnd
;# V01 OutArgs      [V01    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]  
;
; Lcl frame size = 8

G_M64830_IG01:
       50                   push     rax

G_M64830_IG02:
       4885FF               test     rdi, rdi
       7408                 je       SHORT G_M64830_IG05

G_M64830_IG03:
       8B4708               mov      eax, dword ptr [rdi+8]

G_M64830_IG04:
       4883C408             add      rsp, 8
       C3                   ret      

G_M64830_IG05:
       E8D5E2FFFF           call     ConsoleApplication.Program:ThrowArgumentNull()
       CC                   int3     

; Total bytes of code 20, prolog size 1 for method ConsoleApplication.Program:C(ref):int
; ============================================================
; Assembly listing for method ConsoleApplication.Program:D(ref):int
; Emitting BLENDED_CODE for X64 CPU with AVX
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  4,  4   )     ref  ->  rbx         class-hnd
;# V01 OutArgs      [V01    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]  
;
; Lcl frame size = 0

G_M64828_IG01:
       53                   push     rbx
       488BDF               mov      rbx, rdi

G_M64828_IG02:
       488BF3               mov      rsi, rbx
       48BF6080ADC6377F0000 mov      rdi, 0x7F37C6AD8060
       E872F9FFFF           call     ConsoleApplication.ThrowHelper:ThrowIfArgumentNull(ref)
       8B4308               mov      eax, dword ptr [rbx+8]

G_M64828_IG03:
       5B                   pop      rbx
       C3                   ret      

; Total bytes of code 27, prolog size 1 for method ConsoleApplication.Program:D(ref):int
; ============================================================
; Assembly listin42
g for method ConsoleApplication.Program:E(ref):int
; Emitting BLENDED_CODE for X64 CPU with AVX
; optimized code
; rsp based frame
; partially interruptible
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  5,  5   )     ref  ->  rdi         class-hnd
;  V01 tmp0         [V01,T01] (  3,  0   )     ref  ->  rbx         class-hnd exact
;  V02 tmp1         [V02,T02] (  2,  0   )     ref  ->  rsi        
;# V03 OutArgs      [V03    ] (  1,  1   )  lclBlk ( 0) [rsp+0x00]  
;
; Lcl frame size = 0

G_M64828_IG01:
       53                   push     rbx

G_M64828_IG02:
       4885FF               test     rdi, rdi
       7405                 je       SHORT G_M64828_IG05

G_M64828_IG03:
       8B4708               mov      eax, dword ptr [rdi+8]

G_M64828_IG04:
       5B                   pop      rbx
       C3                   ret      

G_M64828_IG05:
       48BF301658C6377F0000 mov      rdi, 0x7F37C6581630
       E8A62E9678           call     CORINFO_HELP_NEWSFAST
       488BD8               mov      rbx, rax
       BF01000000           mov      edi, 1
       48BE603D26C5377F0000 mov      rsi, 0x7F37C5263D60
       E8AF439678           call     CORINFO_HELP_STRCNS
       488BF0               mov      rsi, rax
       488BFB               mov      rdi, rbx
       E8042760FF           call     System.ArgumentNullException:.ctor(ref):this
       488BFB               mov      rdi, rbx
       E89C249778           call     CORINFO_HELP_THROW
       CC                   int3     

; Total bytes of code 69, prolog size 1 for method ConsoleApplication.Program:E(ref):int
; ============================================================

Discussion

As of dotnet/coreclr#6103 A, B, and C produce the same code.

There is even a further improvement when (string-) arguments must be passed to the ThrowHelper.
See Reference source -- ThrowHelper.

String argument in callee

G_M57615_IG01:
       55                   push     rbp
       488BEC               mov      rbp, rsp

G_M57615_IG02:
       85F6                 test     esi, esi
       7C07                 jl       SHORT G_M57615_IG05

G_M57615_IG03:
       8BC6                 mov      eax, esi
       C1E005               shl      eax, 5

G_M57615_IG04:
       5D                   pop      rbp
       C3                   ret      

G_M57615_IG05:
       E8D4FBFFFF           call     ConsoleApp3.Strings:get_Unknown():ref
       488BF8               mov      rdi, rax
       E8DCFBFFFF           call     ConsoleApp3.ThrowHelper:ThrowException(ref)
       CC                   int3     

; Total bytes of code 29, prolog size 4

Without string argument in callee

G_M57615_IG01:
       50                   push     rax

G_M57615_IG02:
       85F6                 test     esi, esi
       7C0A                 jl       SHORT G_M57615_IG05

G_M57615_IG03:
       8BC6                 mov      eax, esi
       C1E005               shl      eax, 5

G_M57615_IG04:
       4883C408             add      rsp, 8
       C3                   ret      

G_M57615_IG05:
       BF01000000           mov      edi, 1
       E8AFFBFFFF           call     ConsoleApp3.ThrowHelper:ThrowException(int)
       CC                   int3     

; Total bytes of code 26, prolog size 1

This is produced by:

public class Foo
{
    public int Do(int a)
    {
        if (a < 0) ThrowHelper.ThrowException(ThrowHelper.Reason.Unknown);

        return a * 32;
    }
}

internal static class ThrowHelper
{
    public static void ThrowException(Reason reason) => throw new Exception(GetMessage(reason));

    private static string GetMessage(Reason reason)
    {
        switch (reason)
        {
            case Reason.ArgumentOutOfRange:
                return Strings.ArgumentOutOfRange;
            case Reason.Unknown:
                return Strings.Unknown;
            default:
                return string.Empty;
        }
    }

    public enum Reason
    {
        ArgumentOutOfRange,
        Unknown
    }
}

Also see dotnet/extensions#324 (comment)