[cfe-dev] Debug Info and Multi-Line statements (particularly "do" statements)

[Eric Christopher]

On Fri, Jan 25, 2013 at 3:42 PM, Richard Smith <richard at metafoo.co.uk>wrote:

> On Fri, Jan 11, 2013 at 9:25 AM, Peter Ohmann <ohmann at cs.wisc.edu> wrote:
> > Hello all,
> >
> > While I understand that debug data is best-effort, I am running into some
> > trouble with an analysis tool I'm building partially using an LLVM pass.
> > There are two (seemingly directly related) cases where debug data is not
> > missing (which wouldn't be a problem for me) but very misleading.
> >
> > First, in the case of multi-line statements, clang will assign the debug
> > data for each expression to be the first line of the statement but
> continue
> > incrementing the column number past the number of columns on the line.
>  The
> > following code gives an example:
> > [1] int foo(){
> > [2]   int x, y, z;
> > [3]   if(x < y ||
> > [4]      y < z){
> > [5]     x++;
> > [6]   }
> > [7] }
> > In this example, when my LLVM pass gets the bitcode both the (x<y) and
> (y<z)
> > expressions are assigned DebugLocs which have line number 3 (but with
> > increasing column numbers).
>
> When I try this, in the IR produced by 'clang -g', they both have line
> 3 column 0. If I use 'clang -g -gcolumn-info', they both have line 3
> column 3 (the location of the 'if' token). That seems to make somewhat
> more sense, but is still probably not what we want.
>

Yeah, not so much.

Peter: If you get a chance to file a bug in bugzilla so we can track it I'd
appreciate it.

Thanks!

-eric
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