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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/104789] [12 Regression] -Wstringop-overflow
 false positive at -O3 for an unrolled loop
Date: Mon, 14 Mar 2022 17:35:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104789

--- Comment #11 from Martin Sebor <msebor at gcc dot gnu.org> ---
The direct store subset of -Wstringop-overflow that runs in the strlen pass
(i.e., those handled in strlen_pass::handle_store) might be better handled =
in
VRP and issued under -Warray-bounds.  The challenge there is that unlike th=
is
-Wstringop-overflow subset which respects subobject boundaries, -Warray-bou=
nds
intentionally considers complete objects (this was done to avoid false
positives).

So before moving all of strlen a solution to consider is to merge these two
sets of warnings while preserving the subobject sensitivity.

Another (indirectly related) improvement is to also move -Warray-bounds out=
 of
VRP and into the access warning pass, and run it at the same times as most
other warnings there (that would also enable -Warray-bounds at -O0, which m=
ight
of course trigger some new false positives).=