Re: cache uses_template_parms in tree node?

[Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>]

On Thu, 22 Jan 2004, Giovanni Bajo wrote:

> Richard Guenther wrote:
>
> > To address the for_each_template_parm() performance problem, would it
> > be possible to cache the outcome of uses_template_parms() in the tree
> > node? Or would this caching somehow be invalidated later?
> > Just before I start digging into gcc tree's and its wonders :/
>
> To me, the right solution is to get rid of uses_template_parms() altogether. We
> can check for type/value dependness instead (we already have functions for
> that, and we even cache the outcome in the tree as you are suggesting), so it's
> just a matter of removing the old code.
>
> I asked Honza to provide me with some numbers about which calls to
> uses_template_parms are the ones most important from a compile-time point of
> view. I'm willing to look into this when I get the numbers.

For a POOMA testcase, a compile with a instrumented compiler yields the
following gprof callgraph for uses_template_parms:

-----------------------------------------------
                                  29             add_friend <cycle 1> [2505]
                                  38             duplicate_decls <cycle 1> [901]
                                  60             get_bindings_real <cycle 1> [2187]
                                 183             make_friend_class <cycle 1> [2376]
                                 201             tsubst_default_arguments <cycle 1> [3660]
                                 212             check_default_argument <cycle 1> [3591]
                                 528             xref_basetypes <cycle 1> [2131]
                                1001             try_one_overload <cycle 1> [2397]
                                1248             grokdeclarator <cycle 1> [484]
                                4720             instantiate_class_template <cycle 1> [628]
                               13723             expand_or_defer_fn <cycle 1> [2108]
                               20135             maybe_retrofit_in_chrg <cycle 1> [1736]
                               22341             unify <cycle 1> [483]
                               50560             register_specialization <cycle 1> [619]
                               51673             tsubst <cycle 1> [281]
                              150936             template_class_depth_real <cycle 1> [1039]
                              152948             tsubst_template_arg <cycle 1> [811]
                              214778             type_unification_real <cycle 1> [911]
                              270505             coerce_template_parms <cycle 1> [398]
                              459713             lookup_template_class <cycle 1> [242]
                0.00    0.00      14/101229133     bt_instantiate_type_proc <cycle 2> [2629]
                0.00    0.00      40/101229133     cp_parser_check_declarator_template_parameters [1881]
[1229]   0.0    0.03    0.00 1415586         uses_template_parms <cycle 1> [1229]
                             1415586             for_each_template_parm <cycle 1> [333]

Richard.

--
Richard Guenther <richard dot guenther at uni-tuebingen dot de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/