llvm dev - Jul 2011 - [LLVMdev] LexicalScope Debug Info - Line Number

Hi,
I need to find out the line no info for each lexical block in the code
being compiled with llc. The docs mention metadata format for debug
info for lexical block is


!3 = metadata !{
  i32,                                  ;; Tag = 11 + LLVMDebugVersion
(DW_TAG_lexical_block)
  metadata,                         ;; Reference to context descriptor
  i32,                                  ;; Line number
  i32                                   ;; Column number
}

So the line no. info is present as its 3rd member. I am trying to
extract this line number either directly from the corresponding
DbgScope variable passed as argument to
constructScopeDIE function. OR from the ScopeDIE variable (DIE* type)
after it is populated with the debug info in DIE format.

Please help me with the functions which I can use to extract this information.

Thanks and Regards,
Ankur

Ankur,

On Jul 26, 2011, at 7:58 PM, ankur deshwal wrote:
> Hi,
> I need to find out the line no info for each lexical block in the code
> being compiled with llc. The docs mention metadata format for debug
> info for lexical block is
> 
> 
> !3 = metadata !{
>  i32,                                  ;; Tag = 11 + LLVMDebugVersion
> (DW_TAG_lexical_block)
>  metadata,                         ;; Reference to context descriptor
>  i32,                                  ;; Line number
>  i32                                   ;; Column number
> }
> 
> So the line no. info is present as its 3rd member. I am trying to
> extract this line number either directly from the corresponding
> DbgScope variable passed as argument to
> constructScopeDIE function. OR from the ScopeDIE variable (DIE* type)
> after it is populated with the debug info in DIE format.
> 
Metadata is used to encode lexical block at LLVM IR level. However, DbgScope is
internal to DwarfWriter (which is part of code generator)  and it is lowered
from metadata. DbgScope does not need line number information, it is focused on
identify set of instructions for a lexical block.
> Please help me with the functions which I can use to extract this
information.
> 
At what point in compilation you want to extract line number information ? And
what is the intended use ?
-
Devang