[Bug c++/12850] [3.4/3.5 Regression] memory consumption for heavy template instantiations tripled since 3.3

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

------- Additional Comments From hubicka at gcc dot gnu dot org  2004-02-14 14:27 -------
Memory usage is now at 104MB that is still more than 3.3 did, but give that this code is almost perfect testcase where unit-at-a-time shall lose, I think score is not bad.
Mark's patches helped a lot to amount of garbage produced by C++ frontend on mainline now (reducing amount of garbage from 2GB to 700MB), but I think we can do significantly better still.
One problem is large consumption of struct function (about 10% of memory surviving from frontend).  Many of these struct functions are for functions that were never cgraph_finalize_function (either templates or unused functions).  I think these should be freed but I don't know how.
Also C++ frontend still produce a lot of gabrage(39MB of 700MB memory is needed) Major producers are:
varray.c:161 (varray_grow)                                        20496    1473380     401588:1.600%     210256:0.532%
cp/call.c:2181 (add_template_candidate_real)                      96047    2339908      63560:2.051%          0:0.000%
cp/name-lookup.c:1719 (set_identifier_type_value_with_scope)     151575    3031500          0:2.587%          0:0.000%
tree.c:3962 (build_method_type_directly)                          24117    2604636     482340:2.634%    1411456:3.574%
cp/lex.c:773 (copy_decl)                                          31558    3408264          0:2.909%    2979720:7.545%
cp/name-lookup.c:2800 (push_class_level_binding)                 170972    3419440          0:2.918%        140:0.000%
tree-inline.c:1970 (copy_tree_r)                                 176657    3606700       4084:3.081%     551820:1.397%
cp/search.c:1200 (build_baselink)                                168114    4034736          0:3.443%        552:0.001%
cp/pt.c:6252 (tsubst_decl)                                        38668    4176144          0:3.564%    2390580:6.053%
cp/name-lookup.c:4720 (store_bindings)                           221688    4433760          0:3.784%          0:0.000%
cp/pt.c:5738 (tsubst_template_args)                              248319    5966576      74480:5.155%     570592:1.445%
function.c:6397 (allocate_struct_function)                         9158    4688896    1978128:5.689%    4087720:10.351%
cp/pt.c:3814 (coerce_template_parms)                             282818    6655016      65496:5.735%      46156:0.117%
tree.c:3908 (build_function_type)                                 57993    6263244    1159860:6.335%     332672:0.842%
(first percentage is garbage allocated, second percentage is amount of memory surviving to cgraph_optimize)
Backend looks better now, produce about 300MB of additional garbage.  About 10-20% can be saved by better aliasing and moving log links into separate structure.  Overall we went from 4GB garbage to 900MB.
I don't have enought knowledge of templates and name lookup to get things significantly better.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12850