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From: "bugdal at aerifal dot cx" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/95558] Invalid IPA optimizations based on weak definition
Date: Sat, 06 Jun 2020 14:40:45 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95558

--- Comment #3 from Rich Felker <bugdal at aerifal dot cx> ---
In addition to a fix, this is going to need a workaround as well. Do you ha=
ve
ideas for a clean one? A dummy asm in the dummy function to kill pureness is
certainly a big hammer that would work, but it precludes LTO optimization if
the weak definition doesn't actually get replaced, so I don't like that.

One idea I think would work, but not sure: make an external __weak_dummy_ta=
il
function that all the weak dummies tail call to. This should only take a few
bytes more than just returning, and precludes pureness analysis in the TU i=
t's
in, while still allowing DCE at LTO time when the definition of
__weak_dummy_tail becomes available.

Is my reasoning correct here?=