IL Fib with tail call

Fib.il

.assembly ConsoleApp
{
}

.class public auto ansi abstract sealed beforefieldinit Program
    extends System.Object
{
    // Methods
    .method assembly hidebysig static 
        int32 FibAcc (
            int32 a,
            int32 b,
            int32 n
        ) cil managed 
    {
        .maxstack 8

        IL_0000: ldarg.2
        IL_0001: brtrue.s IL_0005

        IL_0003: ldarg.0
        IL_0004: ret

        IL_0005: ldarg.1
        IL_0006: ldarg.0
        IL_0007: ldarg.1
        IL_0008: add
        IL_0009: ldarg.2
        IL_000a: ldc.i4.1
        IL_000b: sub
                 tail.
        IL_000c: call int32 Program::FibAcc(int32, int32, int32)
        IL_0011: ret
    }

    .method public hidebysig static 
        int32 Fib (
            int32 n
        ) cil managed 
    {
        .maxstack 8

        IL_0000: ldc.i4.0
        IL_0001: ldc.i4.1
        IL_0002: ldarg.0
        IL_0003: call int32 Program::FibAcc(int32, int32, int32)
        IL_0008: ret
    }
    
    .method public hidebysig static
        void Main () cil managed
    {
        .entrypoint
        .maxstack 8

        ldc.i4.6
        call int32 Program::Fib(int32)
        call void [System.Console]System.Console::WriteLine(int32)
        ret
    }
}