debug: Ability to see the content of machine registers when debugging .s files

[petr-sneller]

There is currently no way to inspect the content of machine registers. For example if you have some code written in go assemler (.s) file - you can step into that file and even hit a breakpoint, but you cannot see the content of registers, which makes debugging of such files kind of useless.

It would be nice to be able to see the content of machine registers at least in .s files.

[hyangah]

That's a good idea.
With go-delve/delve#2446 (already released as v1.6.1), I am guessing the newest dlv already should provide some degree of support for register content inspection through DEBUG CONSOLE and the watch panel.
https://github.com/go-delve/delve/blob/master/Documentation/cli/expr.md#cpu-registers

But ideally, I hope we can see the list of registers (maybe through the VARIABLES viewlet when we stop at .s?). debugger.ScopeRegisters and debugger.ThreadRegisters look relevant. (https://github.com/go-delve/delve/blob/master/service/rpc2/server.go#L425 for reference)

cc @polinasok @suzmue

[hyangah]

I chat with @suzmue and @polinasok.

Something to think about:

• how to present the value by default?
  • is it sufficient to show as numbers in the hex format, and additional strings for flags such as Rflags as done by dlv cli)?
  • or, should we come up with a creative solution to utilize the richer expression?
• should we set evaluateName? If yes, what that should be?
• wouldn't the new assembly view of VSCode (Roadmap: Disassembly View Feature microsoft/vscode#124163) be more appropriate for assembly code inspection?

[petr-sneller]

I'm on latest golang and delve, but I still cannot see the content of all registers.

I can type XMM0, R15, etc in debug console and it would print a content of a register. But it cannot print XMM16 and above, YMM, ZMM, and K registers.

In my settings, I have:

    "go.delveConfig":{
        "debugAdapter":"dlv-dap",
        "showRegisters": true
    },

But I still don't see any content of registers anywhere.

Is there a plan to fix this somehow?

[suzmue]

Currently the value from the settings is not correctly passed through to the launch configuration. Will send a fix for this.

If you add "showRegisters": "true" to your launch configuration instead, it should work to display the register values.

[gopherbot]

Change https://golang.org/cl/365374 mentions this issue: src/goDebugConfiguration: update list of delveConfig properties

[petr-sneller]

@suzmue That's a good tip, thanks :)

BTW I really enjoy the feature to run a specific test in a .go file, which doesn't really have a launch configuration at all. I wish this worked so I could just click on tests I want to debug like that :)

[hyangah]

The Go Nightly version includes Suzy's change. Would be nice if you can give it a try and verify it works.
Hopefully we release the next version with this fix soon.