really really slow lookup_symtabs() - some obversations

[Roland Schwingel <Roland.Schwingel@onevision.de>]

Hi...

A while ago I posted a patch for gdbtk to avoid lookup_symtab() calls 
because they appear to be
***very*** expensive in my environment. The patch made gdb more usable 
again, but there are
still frequent calls to lookup_symtab() causing *heavy* slowdowns 
(waiting 1 minute for one
lookup_symtab on a P4 1.5GHz is very common for me).

So I started out a new round. I found out that calling  lookup_symtab 
gets desperately slow
when the following 2 circumstances are met:
1. A lot of files involved in the executable (in my case >6000)
2. Calls to lookup_symtab with fully qualified name

I added some printfs in lookup_symtab for debugging:

.....
got_symtab:

  /* First, search for an exact match */

  printf ("lookup_symtab: ALL_SYMTABS\n");
  ALL_SYMTABS (objfile, s)
  {
    if (FILENAME_CMP (name, s->filename) == 0)
      {
      printf ("lookup_symtab: found Case1\n");
    return s;
      }

   ....
 }
  printf ("lookup_symtab: After ALL_SYMTABS\n");

  /* Now, search for a matching tail (only if name doesn't have any dirs) */
  ....

When called with a fully qualifed name I get a cascade of my printf
(at least hundreds mabe thousands) and I takes ages to complete
(as menitioned above) when called with a short name eg "foo.m"
I just get 3 to 8 of my printfs....

Does anyone know why all this is done for fully qualified names?
And maybe what can be done against?

Thanks for any infos,

Roland

PS: All stuff here mentioned concerns gdb 5.3 (to which I have to stick 
until 6.0 is released)