[lldb-dev] [LLVMdev] PDB support in LLVM

Tue Apr 7 10:19:48 PDT 2015

I think that's what I used. Hence why I want lldb C# bindings! But yeah. Horridly underdocumented.

-----Original Message-----
From: "Zachary Turner" <zturner at google.com>
Sent: ‎07/‎04/‎2015 18:10
To: "Colin Riley" <colin at codeplay.com>; "lldb-dev at cs.uiuc.edu" <lldb-dev at cs.uiuc.edu>
Subject: Re: [lldb-dev] [LLVMdev] PDB support in LLVM

Btw the python tools project doesn't use Dbgeng extensibility model, it's a newer richer extensibility framework that is even less documented (most people probably wouldn't even know it exists) but much more powerful. And it's all in managed code, so you get the c# stuff for free.

But still, 4-5 weeks seems very aggressive 

On Tue, Apr 7, 2015 at 9:48 AM Colin Riley <colin at codeplay.com> wrote:

You could try extending the codeview and then relying on the ms linker to emit a pdb from it (last time I checked it converts on the fly - this may have changed recently, and what it converts may not be fully featured). 

The Debug Engine extensibility for visual studio is, as Zach says, not well documented at all. Despite that, in the past I have had LLDB chatting in a limited way to visual studio. It was incredibly messy, and the way I chose to do it was go from Visual Studio -> c# -> c++/CLI -> C++ lldb api. Don't do it that way if you attempt it: Create lldb C# bindings instead and go that direction. I've been looking at that lately but it's a side project so cant be relied on if you need it quickly.

As for the time frame, 4-5 weeks isn't going to get far given the lack of documentation. The debug engine samples don't go far enough in terms of requiring a native C++ environment.

Colin

On 07/04/2015 17:25, Zachary Turner wrote:

It sounds like if you have a time frame of 4-5 weeks, you've got a tall order cut out for yourself.  I don't want to say impossible, but... that's pretty rough.

I think you've got two options:
1) Try to figure out how to emit PDB.  The format is undocumented, so you're kind of on your own here.
2) Try to figure out how to get Visual Studio to understand DWARF.  Visual Studio has a reasonably rich extensibility model which is also not very well documented, so you're probably on your own here as well.  You may want to have a look at PythonTools for Visual Studio.  It's entirely open source and adds Python debugging to Visual Studio.  Obviously you don't need to be able to debug Python, but it's the best source of documentation I know of for extending Visual Studio in this kind of way so maybe it will help.  If you end up doing this, it would be great if you could try to upstream it back to LLDB.  Visual Studio integration with LLDB would be nice to have.

On Mon, Apr 6, 2015 at 5:02 PM Rohan Bajaj <rohanbajaj84 at gmail.com> wrote:

Moving to lldb-dev per suggestion.

Using Visual Studio is only criteria for us. It could be DWARF or PDB.

But I need to implement this soon (4-5 weeks from now). What do you recommend?

Zachary do you also suggest using LLDB on Windows?

On Mon, Apr 6, 2015 at 4:35 PM, Zachary Turner <zturner at google.com> wrote:

On Mon, Apr 6, 2015 at 4:16 PM Chandler Carruth <chandlerc at google.com> wrote:

On Mon, Apr 6, 2015 at 3:46 PM Rohan Bajaj <rohanbajaj84 at gmail.com> wrote:

Is making PDB files for corresponding IR supported in LLVM latest version?

Not today.

After some searching I see llvm-pdbdump, but I want to annotate the IR with debug information so that when I write bitcode it has pdb information.

I've heard of CodeView, but it seems to be only for line information. I want variable values also.

I would be ok to use DWARF if Visual Studio could understand it using LLDB but I don't know how to do that or if it is support.

Zach (CC-ed) and others are actively working on making LLDB work well on Windows, including reading DWARF debug information on Windows and potentially integration with Visual Studio (although I think that is further away at the moment). However, further discussion might be better on the LLDB mailing lists.

It's worth pointing out that CodeView is **not** only for line information. It's for everything.  It's just that LLVM currently only understands a subset of CodeView record types related to line information.

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-- 
- Colin Riley
Senior Director,
Parallel/Graphics Debugger Systems
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