[Bug tree-optimization/44563] GCC uses a lot of RAM when compiling a large numbers of functions

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44563

--- Comment #18 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #17)
> (In reply to Richard Biener from comment #16)
> > callgrind shows the cgraph_edge_hasher quite high in the profile (via
> > redirect_all_calls).  I suppose as the large main is a single BB walking
> > all stmts over-and-over is quite bad.  Also hash_pointer isn't inlined!?
> > Ah - it's external in libiberty hashtab.c ... - it should transition to
> > using/inheriting from pointer_hash.
> > 
> > cgraph_edge *
> > cgraph_node::get_edge (gimple call_stmt)
> > {
> >   cgraph_edge *e, *e2;
> >   int n = 0;
> > 
> >   if (call_site_hash)
> >     return call_site_hash->find_with_hash (call_stmt,
> >                                            htab_hash_pointer (call_stmt));
> > 
> 
> Btw, for 10000 calls (smaller testcase) we get 100 000 000 calls to
> cgraph_edge::redirect_call_stmt_to_callee () (that's from 40000
> redirect_all_calls calls which is from 10000 optimize_inline_calls calls).
> 
> Ah - we do this also for the ENTRY/EXIT block!
> 
> Index: gcc/tree-inline.c
> ===================================================================
> --- gcc/tree-inline.c   (revision 221278)
> +++ gcc/tree-inline.c   (working copy)
> @@ -2802,11 +2802,13 @@ copy_cfg_body (copy_body_data * id, gcov
>         if (need_debug_cleanup
>             && bb->index != ENTRY_BLOCK
>             && bb->index != EXIT_BLOCK)
> -         maybe_move_debug_stmts_to_successors (id, (basic_block) bb->aux);
> -       /* Update call edge destinations.  This can not be done before loop
> -          info is updated, because we may split basic blocks.  */
> -       if (id->transform_call_graph_edges == CB_CGE_DUPLICATE)
> -         redirect_all_calls (id, (basic_block)bb->aux);
> +         {
> +           maybe_move_debug_stmts_to_successors (id, (basic_block) bb->aux);
> +           /* Update call edge destinations.  This can not be done before
> loop
> +              info is updated, because we may split basic blocks.  */
> +           if (id->transform_call_graph_edges == CB_CGE_DUPLICATE)
> +             redirect_all_calls (id, (basic_block)bb->aux);
> +         }
>         ((basic_block)bb->aux)->aux = NULL;
>         bb->aux = NULL;
>        }
> 
> makes sense?

Fails to bootstrap :/  But would improve the testcase to only have the
inline heuristic issue.

/space/rguenther/src/svn/trunk/libstdc++-v3/libsupc++/pbase_type_info.cc: In
member function âvirtual bool __cxxabiv1::__pbase_type_info::__do_catch(const
std::type_info*, void**, unsigned int) constâ:
/space/rguenther/src/svn/trunk/libstdc++-v3/libsupc++/pbase_type_info.cc:32:6:
error: reference to dead statement
 bool __pbase_type_info::
      ^
# .MEM = VDEF <.MEM>
_30 = OBJ_TYPE_REF(_28;(const struct __pbase_type_info)this_3(D)->6)
(this_3(D), thr_type_5(D), thr_obj_9(D), outer_29);
_ZNK10__cxxabiv117__pbase_type_info10__do_catchEPKSt9type_infoPPvj/74 (virtual
bool __cxxabiv1::__pbase_type_info::__do_catch(const std::type_info*, void**,
unsigned int) const) @0x2aaaac8d3ab8
  Type: function definition analyzed
  Visibility: externally_visible public visibility_specified virtual
  Address is taken.
  References: _ZNK10__cxxabiv117__pbase_type_info15__pointer_catchEPKS0_PPvj/34
(addr) (speculative)
  Referring: _ZTVN10__cxxabiv117__pbase_type_infoE/77 (addr)
  Availability: overwritable
  First run: 0
  Function flags: body
  Called by: 
  Calls: strcmp/85 (0.39 per call) __cxa_bad_typeid/83 (can throw external)
strcmp/85 (0.61 per call) 
   Indirect call(0.11 per call) (can throw external) 
   Polymorphic indirect call of type const struct __pbase_type_info
token:6(speculative) (0.03 per call) (can throw external)  of param:0
    Outer type (dynamic):struct __pbase_type_info (or a derived type) offset 0
/space/rguenther/src/svn/trunk/libstdc++-v3/libsupc++/pbase_type_info.cc:32:6:
internal compiler error: verify_cgraph_node failed
0xa8eebc cgraph_node::verify_node()
        /space/rguenther/src/svn/trunk/gcc/cgraph.c:3115
0xa8473f symtab_node::verify()
        /space/rguenther/src/svn/trunk/gcc/symtab.c:1103
0x1025861 optimize_inline_calls(tree_node*)
        /space/rguenther/src/svn/trunk/gcc/tree-inline.c:4938

> > The estimate_calls_size_and_time portion is quite smaller.
> > 
> > cleanup-cfgs main portion is split_bb_on_noreturn_calls.