Re: Global object constructors

[Michael Vance <briareos at lokigames dot com>]

On Wed, Nov 03, 1999 at 10:53:00PM +0100, Martin v. Loewis wrote:

> As a starting point, please share with us what platform you are
> working on. Assuming it is ELFish, here is how you could approach the
> problem:

i686-pc-linux-gnu, based off of RH6.0, so yes, ELF.
 
> - set a break point on __do_global_ctors_aux. Unfortunately, in the

>   - using nm, find the address of the copy of __do_global_ctors_aux

This works. Unfortunately in the abscence of debugging information,
the breakpoint is tinfo2.cc ;).
 
> - read the code of __do_global_ctors_aux to see what it does. Even
>   better, compile it with -g :-(

I have read it (assuming this is it, from gcc/crtstuff.c):

static func_ptr __CTOR_END__[];
static void
__do_global_ctors_aux (void)
{
  func_ptr *p;
  for (p = __CTOR_END__ - 1; *p != (func_ptr) -1; p--)
    (*p) ();
}

Fair enough. I'm recompiling with -g so that it will be a bit more
comprehensible (editing gcc/Makefile, replace -g1 with -g).

Hm, this doesn't help. It thinks the line number is tinfo2.cc:300
still.

> - Singe-step through that, with instruction steps (si). This will
>   eventually get into

Eesh, I get to go through all of the dlopen() stuff because of a
shared library call early in the constructor list. And then printf
calls in dmalloc_verify()...

Hm, it looks like the culprit is in some nasty, nasty template
code. Specifically, I check the heap before and in the constructor of
a class derived from std::list, and it is fine before, but inside the
derived constructor the heap is bad. Either I'm picking up STL
weirdness (the std::list constructor does a bunch of STL allocates),
or I'm getting bad code generation from gcc in *my* template code in
between the std::list and derived constructor...

Thanks for your help,

m.

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