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From: "lis8215 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/111376] missed optimization of one bit test on MIPS32r1
Date: Sat, 15 Jun 2024 05:24:17 +0000	[thread overview]
Message-ID: <bug-111376-4-9jUfhHBCwE@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-111376-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111376

--- Comment #12 from Siarhei Volkau <lis8215 at gmail dot com> ---
Highly likely it's because of data dependency, and not direct cost of shift
operations on LoongArch, although can't find information to prove that.
So, I guess it still might get performance benefit in cases where scheduler can
put some instruction(s) between SLL and BGEZ.

Since you have access to hardware you can  measure performace of two variants:
1) SLL+BGEZ
2) SLL+NOT+BGEZ
if their performance is equal then I'm correct and scheduling automaton for
GS464 seems have to be fixed.

From my side I can confirm that SLL+BGEZ is faster than LUI+AND+BEQ on Ingenic
XBurst 1 cores.

  parent reply	other threads:[~2024-06-15  5:24 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-11 18:24 [Bug rtl-optimization/111376] New: " lis8215 at gmail dot com
2024-06-04  6:55 ` [Bug target/111376] " syq at gcc dot gnu.org
2024-06-04  7:00 ` syq at gcc dot gnu.org
2024-06-04  7:06 ` lis8215 at gmail dot com
2024-06-05 11:02 ` syq at gcc dot gnu.org
2024-06-05 16:56 ` syq at gcc dot gnu.org
2024-06-06  9:45 ` lis8215 at gmail dot com
2024-06-06 22:16 ` syq at gcc dot gnu.org
2024-06-07  8:25 ` lis8215 at gmail dot com
2024-06-13  4:50 ` syq at gcc dot gnu.org
2024-06-15  3:22 ` syq at gcc dot gnu.org
2024-06-15  3:24 ` syq at gcc dot gnu.org
2024-06-15  5:24 ` lis8215 at gmail dot com [this message]
2024-06-15  6:47 ` syq at gcc dot gnu.org
2024-06-15  7:18 ` syq at gcc dot gnu.org
2024-06-15  8:13 ` lis8215 at gmail dot com
2024-06-15  8:35 ` lis8215 at gmail dot com
2024-06-18  8:06 ` syq at gcc dot gnu.org
2024-06-19 14:18 ` syq at gcc dot gnu.org

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