Re: Problems with breakpoints in constructors

[Daniel Jacobowitz <drow at mvista dot com>]

On Thu, Aug 05, 2004 at 08:19:13PM +0530, Amit S. Kale wrote:
> Here they. There are two files dump.txt with my changes and dump.orig.txt 
> without them.
> 
> I read the abbreviations related stuff from dwarf document. Also looked at the 
> gcc code that  generates abbreviations. The gcc code looks correct.

Let's take a look at the debug info for your test case.  Beforehand, in
the debug information for MyClass are two declarations - one for
MyClass(void) and one for MyClass(MyClass&).  Then outside of the class
is a DIE for MyClass(void), without PC bounds - this uses
DW_AT_specification.  Then there are two which reference the previous
DIE using DW_AT_abstract_origin and have PC bounds.  This all makes
sense.  There is no DIE for the copy constructor, which makes sense
because there is no declaration.

Your change adds to the class's members two additional copies of the
void constructor, with linkage names.  It also adds two copies of the
copy constructor, with linkage names.  The debug information now claims
that the class has six member constructors.  The four new members have
no explicit reference to the previous two, from which they are derived.
The concrete DIEs for the clones reference the same abstract DIE they
did before your change, not the new DIEs you have added.  This is not
an improvement.

If anything, it might be useful to add the linkage name to the concrete
dies for the clones.

> Something is messed up in the dwarfdump utility output. I can't find correct 
> abbreviations tags in debug_info. The dump_info records for 2 instances of 
> MyClass and 1 instance of afun contain DW_AT_MIPS_linkage_name attribute. 
> Both of them point to the same abbreviation entry. Yet when I debugged gdb's 
> read_partial_die function, I found that the abbreviation entry for afun and 
> MyClass is different. The afun entry contains 7 attributes, including 
> DW_AT_MIPS_linkage_name and MyClass entry contains 6 attributes, without the 
> MIPS entry.
> 
> How do I verify whether what dwarfdump output shows is incorrect or whether 
> gdb's interpretation of the dwarf data is incorrect?

I don't know anything about dwarfdump.  But the dumps you sent did not
show this.  Dwarfdump doesn't even print the abbreviation number used
by a particular DIE in its output.

-- 
Daniel Jacobowitz