[LLVMdev] Mapping bitcode to source code

[Trevor Harmon]

Hi,

I'm looking for a way to map bitcode to the source code (C/C++) from
which it was generated. For example, the Java class file format has an
optional LineNumberTable attribute that maps each bytecode instruction
to a source code line number:

http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html#22856

Is there something analogous in the LLVM environment? Thanks,

Trevor

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[Duncan Sands]

Hi Trevor,

> I'm looking for a way to map bitcode to the source code (C/C++) from
> which it was generated. For example, the Java class file format has an
> optional LineNumberTable attribute that maps each bytecode instruction
> to a source code line number:
>
> http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html#22856
>
> Is there something analogous in the LLVM environment? Thanks,

this can be done using debug info. Check out
http://llvm.org/docs/SourceLevelDebugging.html

Ciao,

Duncan.

[Trevor Harmon]

On Feb 8, 2010, at 8:51 PM, Duncan Sands wrote:

> this can be done using debug info. Check out
> http://llvm.org/docs/SourceLevelDebugging.html

Wow, that threw me for a loop. I'm using the 2.6 release, thinking I
was up to date, but its debug output doesn't look anything like what's
described in the above link. It appears to document the upcoming 2.7
version, which for some reason produces different debug syntax than
2.6. For example, the llvm.dbg.stoppoint intrinsic function no longer
exists in 2.7, and 2.6 has no "metadata" descriptors. Is there any
information about these changes and why they were necessary?

Also, is there an API for accessing the debug info? I looked through
the Programmer's Manual but didn't see anything.

Thanks,

Trevor

[Trevor Harmon]

On Feb 9, 2010, at 11:13 AM, Trevor Harmon wrote:

> Is there any information about these changes and why they were
> necessary?

I think I found it:

http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt

Still looking for an API to access the metadata...

[Jeffrey Yasskin]

On Tue, Feb 9, 2010 at 3:16 PM, Trevor Harmon <Trevor....@nasa.gov> wrote:
> On Feb 9, 2010, at 11:13 AM, Trevor Harmon wrote:
>
>> Is there any information about these changes and why they were
>> necessary?
>
> I think I found it:
>
> http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt
>
> Still looking for an API to access the metadata...

Does http://llvm.org/doxygen/DebugInfo_8h.html help?

[Devang Patel]

On Tue, Feb 9, 2010 at 11:16 PM, Trevor Harmon <Trevor....@nasa.gov> wrote:
> On Feb 9, 2010, at 11:13 AM, Trevor Harmon wrote:
>
>> Is there any information about these changes and why they were
>> necessary?
>
> I think I found it:
>
> http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt
>
> Still looking for an API to access the metadata...

If you want to map llvm instruction to the source location then try

if (MDNode *N = I->getMetadata("dbg")) { // Where I is an LLVM instruction
DILocation Loc(N); // DILocation is
in DebugInfo.h
unsigned Line = Loc.getLineNumber();
StringRef File = Loc.getFilename();
StringRef Dir = Loc.getDirectory();
}

Note, this is new and it won't work in llvm2.6.
-
Devang