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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/35608] limit-structnest.c fails due to O(n^2) memory usage in
 record_component_alias
Date: Tue, 20 Feb 2024 12:48:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D35608

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2009-11-03 12:18:41         |2024-2-20

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14 shows, at -O2 with LIM4/RBR4 (the testcases setting)

0.55user 0.18system 0:00.73elapsed 100%CPU (0avgtext+0avgdata
798332maxresident)k
0inputs+8outputs (0major+195627minor)pagefaults 0swaps

and with LIM5/RBR5 it blows 64GB.  So here's LIM3/RBR3 as comparison:

0.00user 0.02system 0:00.38elapsed 8%CPU (0avgtext+0avgdata 30988maxresiden=
t)k
53680inputs+104outputs (74major+3608minor)pagefaults 0swaps

re-confirmed and it's the original issue still, though the implementation
detail of record_alias_subset rather record_component_aliases.
record_alias_subset records childrens of the subset as immediate subset
transitively.=