Displays the names of local variables, method arguments and method return values in IDA Pro. (NativeAOT)

[dadavadd]

Hi. I am dealing with the problem of mapping local variables and arguments with returned arguments at functions in IDA Pro. That is, type mapping.

My goal is that when I load a binary into IDA Pro, it will automatically get all the type information it needs in a .pdb file, without having to manually convert pointers to structures from the developer. For example:

What's happening now:

public class Person
{
    public int Id { get; set; }
    public int Age { get; set; }
    public string Name { get; set; }
}

internal class Program
{
    static void Main(string[] args)
    {
        Person person = new Person
        {
            Id = 1,
            Name = "Test",
            Age = 15
        };

        PrintPersonAge(person);
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    private static void PrintPersonAge(Person person)
    {
        Console.WriteLine(person.Age);
    }
}

In the decompiled version from IDA, the arguments are not automatically inserted, although they are specified in Local Types.

repro_Program__PrintPersonAge proc near

var_8= byte ptr -8

push    rbp
push    rdi
sub     rsp, 28h
lea     rbp, [rsp+38h+var_8]
mov     [rbp+10h], rcx
nop
mov     rcx, [rbp+10h]
call    repro_Person__get_Age
mov     [rbp-0Ch], eax
mov     ecx, [rbp-0Ch]
call    System_Console_System_Console__WriteLine_7
nop
nop
add     rsp, 28h
pop     rdi
pop     rbp
retn
repro_Program__PrintPersonAge endp

I decided to use cvdump.exe to see what data is generated, and saw a strange thing:

The type of the process was not specified. I decided to find out what the problem was and it was because the methodTypeIndex variable was not used in the EmitSubprogramInfo method in the “ILCompiler.Compiler\Compiler\ObjectWriter\CodeView\CodeViewSymbolsBuilder.cs” file.

I made the variable write but an additional problem appeared. In the following dump I saw this:


The reference pointed to a completely empty forward ref type, when the full type was under a completely different number:

BUT! Some structures and classes are successfully caught by IDA Pro and shown in the disassembler. That is, after my change, this structure arguments were successfully inserted automatically.

I think the problem is in the file "ILCompiler.Compiler\Compiler\UserDefinedTypeDescriptor.cs" and it has something to do with:

 private Dictionary<TypeDesc, uint> _knownTypes = new Dictionary<TypeDesc, uint>();
 private Dictionary<TypeDesc, uint> _completeKnownTypes = new Dictionary<TypeDesc, uint>();

Most likely, an empty copy of the class is generated initially, so methodTypeIndex may point to it, but I could be wrong. I would be grateful if you could look into this problem.

[MichalStrehovsky]

The method type missing is probably the reason why native debuggers show all methods as not taking any parameters in stack traces. The parameter types however do show up as part of local info, so it doesn't affect debugging method bodies.

Fixing this up is not a huge priority because of how little it affects debugging scenarios. But I'd be happy to review a PR that fixes it.