[LLVMdev] How to read v3.3 dbg metadata using v3.4 LLVM

[James Stark]

Thanks for the pseudo code! I'll give it a try and see how it goes.


On Fri, Jan 24, 2014 at 6:48 PM, Eric Christopher <echristo at gmail.com>wrote:

> On Thu, Jan 23, 2014 at 10:35 PM, James Stark <mrjamesstark at gmail.com>
> wrote:
> > Thanks Eric, but could you give me a little bit more hints or pointers
> > please? I looked into DebugInfo.h, but I'm still not sure how to start.
> It
> > sounds like I'd have to somehow manually extract metadata nodes from an
> > instruction.
> >
>
> You will, yes.
>
> Something like:
>
> LLVMContext Ctx = Module.getContext();
> for each Function f in Module::functions():
>   for each BasicBlock BB in f:
>     for each Instruction I in BB:
>        DebugLoc DL = I.getDebugLoc();
>        DILocation DIL = cast<DILocation>(DL.getAsMDNode(Ctx));
>        unsigned Line = DIL.getLine();
>        unsigned Col = DIL.getCol();
>        StringRef Filename = DIL.getFilename();
>
> Or something like that.
>
> -eric
>
> > Thanks,
> > JS
> >
> >
> > On Wed, Jan 22, 2014 at 10:14 PM, Eric Christopher <echristo at gmail.com>
> > wrote:
> >>
> >> This is likely going to be difficult if possible. I wouldn't bet on it
> >> working that way. We've not been trying to keep compatibility between
> >> versions for debug information metadata because the format has been in
> such
> >> flux and upgrading/multiple versions is a significant overhead.
> >>
> >> You might be able to walk the instructions and grab the scope +
> >> line/column that way for each instruction. You can see the format of
> each
> >> metadata node by looking at DebugInfo.h. Hope this helps, feel free to
> send
> >> mail if you have any more questions.
> >>
> >> -eric
> >>
> >> On Wed Jan 22 2014 at 8:59:36 PM, James Stark <mrjamesstark at gmail.com>
> >> wrote:
> >>>
> >>> Hi,
> >>>
> >>> I have bitcode files built by LLVM v3.3 and need to process them using
> >>> v3.4 tools. While I don't expect a lot of backward compatibility in
> LLVM,
> >>> luckily it seems everything's working fine, except for reading source
> line
> >>> information attached to instructions. I use this piece of code [0] to
> get
> >>> source line information. For v3.4, instruction.getMetadata returns
> NULL.
> >>>
> >>> I used llvm-dis to see what's going on. For a sample program [1],
> >>> llvm-dis v3.3, of course, didn't have problems and dumped [2], showing
> dbg
> >>> info. However, llvm-dis v3.4 seemed to have problems grabbing the dbg
> info
> >>> [3].
> >>>
> >>> Any idea how I can modify the code [0] to solve the problem? Attached
> is
> >>> the bitcode file used as an example in this mail. It was complied with
> clang
> >>> v3.3 -g -O0.
> >>>
> >>> Thanks,
> >>> James
> >>>
> >>> [0]
> >>>
> >>> llvm::LLVMContext llvmContext;
> >>>
> >>> unsigned dbgKind = llvmContext.getMDKindID("dbg");
> >>>
> >>> if (MDNode *N = instruction.getMetadata(dbgKind)){
> >>>
> >>>     DILocation location(N);
> >>>
> >>>     fileDirectoryName = location.getDirectory();
> >>>
> >>>     fileName = location.getFilename();
> >>>
> >>>     lineNumber = location.getLineNumber();
> >>>
> >>>     columnNumber = location.getColumnNumber();
> >>>
> >>> }
> >>>
> >>> [1]
> >>>
> >>> int main(int argc, char **argv){
> >>>
> >>>    return 0;
> >>>
> >>> }
> >>>
> >>> [2]
> >>>
> >>> define i32 @main(i32 %argc, i8** %argv) #0 {
> >>>
> >>> entry:
> >>>
> >>>   %retval = alloca i32, align 4
> >>>
> >>>   %argc.addr = alloca i32, align 4
> >>>
> >>>   %argv.addr = alloca i8**, align 8
> >>>
> >>>   store i32 0, i32* %retval
> >>>
> >>>   store i32 %argc, i32* %argc.addr, align 4
> >>>
> >>>   call void @llvm.dbg.declare(metadata !{i32* %argc.addr}, metadata
> !12),
> >>> !dbg !13
> >>>
> >>>   store i8** %argv, i8*** %argv.addr, align 8
> >>>
> >>>   call void @llvm.dbg.declare(metadata !{i8*** %argv.addr}, metadata
> >>> !14), !dbg !13
> >>>
> >>>   ret i32 0, !dbg !15
> >>>
> >>> }
> >>>
> >>> [3]
> >>>
> >>> define i32 @main(i32 %argc, i8** %argv) #0 {
> >>>
> >>> entry:
> >>>
> >>>   %retval = alloca i32, align 4
> >>>
> >>>   %argc.addr = alloca i32, align 4
> >>>
> >>>   %argv.addr = alloca i8**, align 8
> >>>
> >>>   store i32 0, i32* %retval
> >>>
> >>>   store i32 %argc, i32* %argc.addr, align 4
> >>>
> >>>   store i8** %argv, i8*** %argv.addr, align 8
> >>>
> >>>   ret i32 0
> >>>
> >>> }
> >
> >
>
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