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From: "lukas.graetz@tu-darmstadt.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/111643] New: __attribute__((flatten)) with -O1 runs out of
 memory (killed cc1)
Date: Fri, 29 Sep 2023 19:49:28 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111643

            Bug ID: 111643
           Summary: __attribute__((flatten)) with -O1 runs out of memory
                    (killed cc1)
           Product: gcc
           Version: 13.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: lukas.graetz@tu-darmstadt.de
  Target Milestone: ---

Created attachment 56017
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D56017&action=3Dedit
C file

When I run

    gcc -c -O0 runs_out_of_memory.i -o runs_out_of_memory.o

(see the attached .i file) everything is fine. But when I run

    gcc -c -O1 runs_out_of_memory.i -o runs_out_of_memory.o

then I get:

    gcc: fatal error: Killed signal terminated program cc1

Apparently, quickly runs out of memory. I have 16 GB ram and the program is
rather simple. I tested it with gcc versions 9.4.0, 5.1 and 13.2 (target
x86_64-linux-gnu) on ubuntu 20.04.

I believe the problem is the __attribute__((flatten)) on several methods.

How I created the source file: The code comes from busybox (file
coreutils/expr.c) and musl header files. Additionally, I replaced every
function 'name' with 'name_original' and added a wrapper with
__attribute__((flatten)), for later instrumentation (I did this with a scri=
pt).
I used that attribute, because to reduce the overhead of the wrapper functi=
ons
and I believe this should be fine. My reason why I introduced the wrappers =
in
the first place was to allow a fine-grained instrumentation of these functi=
ons.=