Re: gdb 6.3 C++ breakpoint in constructor/destructor patch

Thomas Maier
2005-05-01T20:54:33Z

Hello,

On Sun, 1 May 2005 15:05:32 -0400, Daniel Jacobowitz <drow@false.org>
wrote:

> On Sun, May 01, 2005 at 08:32:12PM +0200, Thomas Maier wrote:
>> Hello,
>>
>> I want to supply a patch for the released gdb 6.3, that fixes partially
>> the gdb bugs
>>
>> gdb/1091: Constructor breakpoints ignored
>> gdb/1193: g++ 3.3 creates multiple constructors: gdb 5.3 can't set
>> breakpoints
>>
>> I was really confused, why my programs to not stop at the breakpoint in
>> constructor/destructors. Now i know, it is not the fault of my programs
>> ;)
>> Since this anoying problem seems to be in gdb since the gcc 3.x
>> release, i
>> guess, no one else a) has this problem (i don't believe so) or b) will
>> not
>> fix it. So i did it ;)
>>
>> This modification is only made for commands like "break
>> [source]:<lineno>". For C++ constructors and destructors, the patch
>> creates more than one breakpoint at the source at lineno, but each
>> generated breakpoint will have another address!
>>
>> NOTE: this is only a simple "hack". I have spent only one day to get
>> into
>> gdb source code and do the modification.
>> It would be better, to create only one breakpoint in such
>> C++ constructors
>> and destructors and assign multiple addresses to it. But this needs a
>> huge
>> modification of gdb, i guess ;)
>
> This is not a very useful change, because it only handles the case
> where everything at a particular line is in the same symtab. Often
> this will not be the case.

Ok, hmm, then the code in find_line_symtab() must not return one symtab,
which is used to find one or more references to the lineno, it must return
a list of symtabs with references to this lineno. Means, a similar search
over all symtabs which is already done in find_line_symtab().
Would that be enough to handle the file:lineno case?

(If yes it think a new function like find_multi_line_symtab() is the best
way to do it, then in decode_all_digits() fill in the sals with the found
symtabs + linenos)

> If you take a look at the archives for the list, you will find a lot of
> discussion on this subject - as well as a prototype patch I posted
> earlier this year. That patch may be good enough for your needs, since
> it handles the file:lineno case. But it isn't done yet, and I haven't
> had time to go back to it yet.
>

Intresting...

-Thomas Maier