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From: "gkm at rivosinc dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/112758] [13/14 Regression] Inconsistent
 Bitwise AND Operation Result between int and long long int
Date: Sat, 16 Dec 2023 18:43:35 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
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X-Bugzilla-Keywords: needs-bisection, wrong-code
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112758

--- Comment #14 from Greg McGary <gkm at rivosinc dot com> ---
I bisected to here for the commit that broke the non-Zbs case:
https://github.com/gcc-mirror/gcc/commit/2e886eef7f2b5aadb00171af868f0895b6=
47c3a4

... and here for Zbs case:
https://github.com/gcc-mirror/gcc/commit/4e1e0d79ecbe8727cb69d4cd97b20c71ca=
aefafc

Note that the Zbs break happens with the commit that introduces Zbs handlin=
g,
i.e., it never worked with Zbs from the beginning.

In the non-Zbs case, it was the introduction of the insn_and_split pattern =
for
single-insn materialization of negative constants that allows the combiner =
to
create the problematic insn.=