[aarch64] GCC 4.9.4 stack deallocation bug

OpenSubmitted by Leo Famulari.
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  • Leo Famulari
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Leo Famulari wrote on 12 Jan 23:01 +0100
(address . bug-guix@gnu.org)
X/4cUenGXImGF9Lz@jasmine.lan
There was a bug in GCC 4.9.4 that could cause miscompilation, such thatthe "compiler was freeing the function's stack frame prior to the end ofthe function itself." [0]
The bug was observed to cause corruption of ext4 filesystems on theaarch64 platform.
The upstream report is here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
Apparently this was fixed in GCC 5, but never backported to the 4.9series.
Should we fix it? We use GCC 4.9 to bootstrap the system in (gnupackages commencement), and a handful of packages depend on it.
[0]https://lwn.net/SubscriberLink/842122/40442a015222c028/
?