Breaking on C labels?

Joel Brobecker
2007-01-25T19:48:15Z

Hello,

A customer asked us a question about the ability of breaking on labels
inside C code. Consider for instance:

void
procedure foo (void)
{
[...]
error_handler:
[...]
}

The customer asked if it was possible to break at the error_handler
label. We are helping them with finding alternative solutions, but
I still did a bit of researching...

I discovered without much surprise that DWARF does indeed have provision
for labels (DW_TAG_label). However, I also noticed that GCC already
generates the associated DIEs. We actually even process them. However,
all my attempts in trying to reference them from the debugger failed.
I tried "break error_handler", or more simply "p error_handler", etc.

Did we ever make any attempt in implementing this sort of functionality
in the past?

Looking at the source code, I found in new_symbol ():

case DW_TAG_label:
attr = dwarf2_attr (die, DW_AT_low_pc, cu);
if (attr)
{
SYMBOL_VALUE_ADDRESS (sym) = DW_ADDR (attr) + baseaddr;
}
SYMBOL_CLASS (sym) = LOC_LABEL;
break;

So we setup the symbol, but we don't add to any of our symbol lists...
I am left wondering what it is that we'll be doing with this symbol.

Thanks,
--
Joel, curious