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From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/109137] [12 regression] Compiling ffmpeg with -m32 on
 x86_64-pc-linux-gnu hangs on libavcodec/h264_cabac.c since
 r12-9086-g489c81db7d4f75
Date: Thu, 30 Mar 2023 15:16:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109137

--- Comment #21 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Zen 1-3 changes were intentional in the original tuning patch (it is also
briefly mentioned in the commit message).  By allowing 256 bit AVX moves
instead of 64bit integer moves (or 128bit) we can move bigger blocks of mem=
ory
without loops and it was faster in micro-benchmarks I made on all zens, eve=
n on
znver1.
We also automatically go for 128bit moves when ISA allows that.

We could revert that part of backport, but won't we get same hangs with
-march=3Dznver4 or core512 which also enables avx512 moves? (I am rebuilding
gcc12 to see what happens)=