step into assembly? [rust]

[smallstepman]

while playing with vscode today, I discovered it's possible to step into assembly and jump around stack frames

vscode auto-generated the following config

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug executable 'cp-sandbox'",
            "cargo": {
                "args": [
                    "build",
                    "--bin=cp-sandbox",
                    "--package=cp-sandbox"
                ],
                "filter": {
                    "name": "cp-sandbox",
                    "kind": "bin"
                }
            },
            "args": [],
            "cwd": "${workspaceFolder}"
        },
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug unit tests in executable 'cp-sandbox'",
            "cargo": {
                "args": [
                    "test",
                    "--no-run",
                    "--bin=cp-sandbox",
                    "--package=cp-sandbox"
                ],
                "filter": {
                    "name": "cp-sandbox",
                    "kind": "bin"
                }
            },
            "args": [],
            "cwd": "${workspaceFolder}"
        }
    ]
}

I tried doing the same with GDB in dap-mode. Steping into does something in the background but it doesn't open an emacs buffer with asm code.

Is there a similar feature in dap-mode? Does it matter whether I use GDB or LLDB?

[yyoncho]

It is something that has to be implemented on our side, but definitely possible(unless it is a proprietary feature/debug adapter).

[smallstepman]

Interesting! I tried looking around for more info:
This is the extension I used: https://github.com/vadimcn/vscode-lldb
I believe this is the line responsible for the printing: https://github.com/vadimcn/vscode-lldb/blob/0ece78ec15eda432be7c9e4392aaec9404c29942/adapter/src/disassembly.rs#L233

[eshelyaron]

There are a couple of features defined in the DAP specification that aren't implemented in dap-mode (yet), I also have discovered that disassembly is one of them while working on the SWI Prolog debug adapter server.

Basically if I understand correctly, dap-mode needs to implement the disassemble DAP request to fetch and display the instruction sequence, as well as add the granulatity field to the stepIn request, setting the granularity to instruction.