https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92442
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org,
| |jason at gcc dot gnu.org,
| |mark at gcc dot gnu.org
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The pubtables cause us to keep otherwise unused type DIEs:
/* Also set the mark on nodes referenced from the pubname_table. Enumerators
are unusual in that they are pubnames that are the children of pubtypes.
They should only be marked via their parent DW_TAG_enumeration_type die,
not as roots in themselves. */
FOR_EACH_VEC_ELT (*pubname_table, i, pub)
if (pub->die->die_tag != DW_TAG_enumerator)
prune_unused_types_mark (pub->die, 1);
and the pubtables itself are not set up to avoid duplicates. I would guess
for code like Boost Spirit we have gazillions of fancy template instantiations
getting pubnames which blows memory use. Not sure why -gsplit-dwarf requires
those or if in the modern C++ world the pubnames section are still useful?
size_of_pubnames () at output_pubnames computes 1331806040, "only" 1.3GB
(for generated DWARF), for the data structure in GCC itself we have
19136 entries in pubname_table and 90654 in the pubtype_table which
computes to 3.0GB data.
Overall this hardly sounds useful, esp. if pubname "creation" is done
before unused type pruning. Not sure why we have add_pubname sprinkled
all over dwarf2out rather than gathering pubnames from a DIE tree walk
at some suitable point (after type pruning, possibly at dwarf2out_early_finish
time before breaking out comdats).
