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From: "dumoulin.thibaut at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/68606] Reduce or disable the static emergency pool
 for C++ exceptions
Date: Wed, 28 Sep 2022 14:42:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D68606

--- Comment #12 from Thibaut M. <dumoulin.thibaut at gmail dot com> ---
Thank you for the updated link!

The problem with the original code is that it malloc unconditionally at lea=
st
2.4ko on the heap. This cannot be avoided when liking with libstdc++.
This malloc is done very early, when initializing `.init_array` section (in
ResetHandler on an ARM Cortex M for example).

As 2.4ko is a lot for some embedded systems, it would be nice to avoid this
behavior.
Also, even if this code is never used in your project, none of the symbols =
in
eh_malloc.cc are called; the constructor of the global variable `pool
emergency_pool;` calls a non-pure functions, compiler cannot get rid of this
function.

If you do not use this code in your project, it will cost you, unconditiona=
lly,
2.4ko of heap.
This is the problem.

This patch https://gcc.gnu.org/legacy-ml/gcc-patches/2016-12/msg01158.html
seems a nice solution, it allocates a static buffer and if nobody is using =
it,
it can be stripped by the linker.=