goto语句会影响C＃的性能吗

Question

Is there performance impact of GOTO statement in c# code, instead of using loop or multiple separate user defined functions .

I am not sure but memory jump may occur with GOTO statement and can impact performance.

Answer 1

No, it doesn't.

It's hard to answer "does it impact peformance" without knowing what the alternative is but I'll make up a sample:

using System;
public class C {
    public void M() {
        var x = 7;
        switch(x) // START SWITCH
        {
            case 1:
                Console.WriteLine("Hello");
                break;
            case 2:
                Console.WriteLine("World");
                break;
            default:
                Console.WriteLine("Uh...");
                break;
        }
        // END SWITCH
        // START GOTO
        if (x == 1)
        {
            goto Hello;
        }
        else if (x == 2)
        {
            goto World;
        }
        Console.WriteLine("Uh...");
        goto End;
    Hello:
        Console.WriteLine("Hello");
        goto End;
    World:
        Console.WriteLine("World");
    End:
        // END GOTO
        Console.WriteLine("Done");
    }
}

Compiling this with C# in release mode (using sharplab.io default 2.9.0) yields the following IL (ie bytecode for you Java folk):

.class private auto ansi '<Module>'
{
} // end of class <Module>

.class public auto ansi beforefieldinit C
    extends [mscorlib]System.Object
{
    // Methods
    .method public hidebysig 
        instance void M () cil managed 
    {
        // Method begins at RVA 0x2050
        // Code size 99 (0x63)
        .maxstack 2
        .locals init (
            [0] int32
        )

        IL_0000: ldc.i4.7
        IL_0001: stloc.0
        // START SWITCH
        IL_0002: ldloc.0
        IL_0003: ldc.i4.1
        IL_0004: beq.s IL_000c

        IL_0006: ldloc.0
        IL_0007: ldc.i4.2
        IL_0008: beq.s IL_0018

        IL_000a: br.s IL_0024

        IL_000c: ldstr "Hello"
        IL_0011: call void [mscorlib]System.Console::WriteLine(string)
        IL_0016: br.s IL_002e

        IL_0018: ldstr "World"
        IL_001d: call void [mscorlib]System.Console::WriteLine(string)
        IL_0022: br.s IL_002e

        IL_0024: ldstr "Uh..."
        IL_0029: call void [mscorlib]System.Console::WriteLine(string)
        // END SWITCH
        // START GOTO
        IL_002e: ldloc.0
        IL_002f: ldc.i4.1
        IL_0030: beq.s IL_0042

        IL_0032: ldloc.0
        IL_0033: ldc.i4.2
        IL_0034: beq.s IL_004e

        IL_0036: ldstr "Uh..."
        IL_003b: call void [mscorlib]System.Console::WriteLine(string)
        IL_0040: br.s IL_0058

        IL_0042: ldstr "Hello"
        IL_0047: call void [mscorlib]System.Console::WriteLine(string)
        IL_004c: br.s IL_0058

        IL_004e: ldstr "World"
        IL_0053: call void [mscorlib]System.Console::WriteLine(string)
        // END GOTO
        IL_0058: ldstr "Done"
        IL_005d: call void [mscorlib]System.Console::WriteLine(string)
        IL_0062: ret
    } // end of method C::M

    .method public hidebysig specialname rtspecialname 
        instance void .ctor () cil managed 
    {
        // Method begins at RVA 0x20bf
        // Code size 7 (0x7)
        .maxstack 8

        IL_0000: ldarg.0
        IL_0001: call instance void [mscorlib]System.Object::.ctor()
        IL_0006: ret
    } // end of method C::.ctor

} // end of class C

The switch form has 3 beq and 1 br.s and the goto form has 2 beq and 2 br.s , other than that they are identical. The cost of br.s is presumably less than or equal to the cost of beq so the cost of the goto approach is not greater than the cost of the switch approach.

Finally, using goto is a bad idea. If you want to argue about that fact please do so on a different question like this one: What is wrong with using goto?