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From: "ajidala at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/100745] GCC generates suboptimal assembly from vector extensions on AArch64 Date: Mon, 24 May 2021 20:27:45 +0000 [thread overview] Message-ID: <bug-100745-4-Lcn6g4vqrV@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-100745-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100745 --- Comment #1 from Nicolas F. <ajidala at gmail dot com> --- I'll attach a second version of profile.c, with the vector extension code that's actually going to be used in mpv (some cleanup has been done). Performance is unchanged. Some absolute numbers from gcc 11.1.0: $ ./profile old: 811703 nicolas: 262007 (3.10x as fast) niklas: 679524 (1.19x as fast) Some absolute numbers from Clang -O3: $ ./profile old: 1547552 nicolas: 269081 (5.75x as fast) niklas: 246508 (6.28x as fast) As you can see, Clang does significantly worse on the C version (yay GCC!), but significantly, and most importantly, in absolute terms, better on the vector version. Like more than twice as fast than GCC's code. Looking at GCC's assembly output, I can see some odd choices, such as shuffling vectors around on the stack instead of using the other scratch registers (v21-v30), whereas clang does use those scratch registers.
next prev parent reply other threads:[~2021-05-24 20:27 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-24 14:11 [Bug target/100745] New: " ajidala at gmail dot com 2021-05-24 20:27 ` ajidala at gmail dot com [this message] 2021-05-24 20:28 ` [Bug target/100745] " ajidala at gmail dot com 2024-02-27 8:53 ` [Bug tree-optimization/100745] " pinskia at gcc dot gnu.org 2024-04-03 16:54 ` pinskia at gcc dot gnu.org
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