Re: [PATCH] [c++/18141] Fix perf issue

[Doug Evans <dje at google dot com>]

Doug Evans writes:
 > Hi.
 > 
 > The bug report explains the issue hopefully sufficiently:
 > 
 > https://sourceware.org/bugzilla/show_bug.cgi?id=18141
 > 
 > Basically, gdb is looking up "std" in .gdb_index, the index saying
 > it's present, gdb expanding the containing CU, but then the final
 > lookup not finding it.  This leads to expanding one CU in every
 > objfile that has an entry for "std".
 > 
 > A followup patch will add a complaint for this case.
 > In this case it's really an internal error, but I'm not sure
 > it'll always be an internal error, nor whether one can
 > adequately distinguish them.
 > 
 > Regression tested on amd64-linux.
 > 
 > Before:
 > 
 > (gdb) print foo
 > ....
 > Command execution time: 297.609072 (cpu), 761.008252 (wall)
 > Space used: 25874649088 (+20380094464 for this command)
 > #symtabs: 622313 (+621693), #compunits: 8782 (+8774), #blocks: 4377936 (+4373024)
 > 
 > After:
 > 
 > (gdb) print foo
 > ....
 > Command execution time: 0.605912 (cpu), 0.971609 (wall)
 > Space used: 5538639872 (+42561536 for this command)
 > #symtabs: 924 (+304), #compunits: 10 (+2), #blocks: 8950 (+4038)
 > 
 > 2015-03-18  Doug Evans  <dje@google.com>
 > 
 > 	PR c++/18141
 > 	* cp-namespace.c (cp_search_static_and_baseclasses): Always look for
 > 	klass in VAR_DOMAIN.
 > 
 > diff --git a/gdb/cp-namespace.c b/gdb/cp-namespace.c
 > index 4a00cb6..0feeb35 100644
 > --- a/gdb/cp-namespace.c
 > +++ b/gdb/cp-namespace.c
 > @@ -355,8 +355,11 @@ cp_search_static_and_baseclasses (const char *name,
 >    make_cleanup (xfree, nested);
 >  
 >    /* Lookup a class named KLASS.  If none is found, there is nothing
 > -     more that can be done.  */
 > -  klass_sym = lookup_global_symbol (klass, block, domain);
 > +     more that can be done.  KLASS could be a namespace, so always look
 > +     in VAR_DOMAIN.  This works for classes too because of
 > +     symbol_matches_domain (which should be replaced with something else,
 > +     but it's what we have today).  */
 > +  klass_sym = lookup_global_symbol (klass, block, VAR_DOMAIN);
 >    if (klass_sym == NULL)
 >      {
 >        do_cleanups (cleanup);

fyi, committed.