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From: "schnetter at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/99912] Unnecessary / inefficient spilling of AVX2 ymm registers
Date: Mon, 05 Apr 2021 02:03:30 +0000	[thread overview]
Message-ID: <bug-99912-4-3GMNOZADoP@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99912-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99912

--- Comment #2 from Erik Schnetter <schnetter at gmail dot com> ---
I did not describe the scale of the issue. There are more than just a few
inefficient or unnecessary operations:

The loop kernel (a single basic block) extends from address 0x1240 to 0xbf27 in
the attached disassembled object file.

Out of about 6000 instructions in the loop, 1000 are inefficient (and likely
superfluous) moves that copy one 32-byte stack slot into another, using 16-byte
wide copies.

For example, the stack slot 9376(%rsp) is written 9 times in the loop kernel,
but is read only once.

  parent reply	other threads:[~2021-04-05  2:03 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-05  1:53 [Bug target/99912] New: " schnetter at gmail dot com
2021-04-05  1:54 ` [Bug target/99912] " schnetter at gmail dot com
2021-04-05  2:03 ` schnetter at gmail dot com [this message]
2021-04-06  8:25 ` rguenth at gcc dot gnu.org
2021-04-06 14:42 ` schnetter at gmail dot com
2021-04-06 16:33 ` schnetter at gmail dot com
2021-04-07  9:36 ` rguenth at gcc dot gnu.org
2021-04-07 16:48 ` rguenth at gcc dot gnu.org
2021-04-27 13:17 ` cvs-commit at gcc dot gnu.org
2021-04-27 13:17 ` cvs-commit at gcc dot gnu.org
2021-04-27 14:02 ` rguenth at gcc dot gnu.org
2021-04-27 16:03 ` schnetter at gmail dot com
2021-04-29  6:32 ` cvs-commit at gcc dot gnu.org

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