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From: "jamborm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108351] [13 Regression] Dead Code Elimination Regression at -O3 since r13-4240-gfeeb0d68f1c708
Date: Fri, 17 Feb 2023 12:52:34 +0000	[thread overview]
Message-ID: <bug-108351-4-y1U88qdlsX@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108351-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108351

--- Comment #5 from Martin Jambor <jamborm at gcc dot gnu.org> ---
If you rename main to something else, like bar, and so the calls to f
outside of the loop are not considered cold, you get the GCC 12
behavior.  Is this reduced from a real-world problem?

Because on the testcase IPA-CP actually does what I would like it to
do, it iginores the first parameter because really IPA-SRA is better
placed to deal with it and then does not duplicate f for the cold
calls.

The fact that the GCC 12 heuristics first cloned for a constant in a
useless parameter in the loop and then, when removing it in the other
calls, it happened to find out that those two share the same constant
in the second parameter, which happened to make the function shorter,
is basically luck rather than design.

  parent reply	other threads:[~2023-02-17 12:52 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-10 11:46 [Bug tree-optimization/108351] New: Dead Code Elimination Regression at -O3 (trunk vs. 12.2.0) yann at ywg dot ch
2023-01-10 12:10 ` [Bug tree-optimization/108351] [13 Regression] " rguenth at gcc dot gnu.org
2023-01-10 14:41 ` [Bug tree-optimization/108351] [13 Regression] Dead Code Elimination Regression at -O3 since r13-4240-gfeeb0d68f1c708 marxin at gcc dot gnu.org
2023-01-10 22:48 ` pinskia at gcc dot gnu.org
2023-02-15  9:09 ` yinyuefengyi at gmail dot com
2023-02-15  9:15 ` yinyuefengyi at gmail dot com
2023-02-17 12:52 ` jamborm at gcc dot gnu.org [this message]
2023-04-08 14:38 ` law at gcc dot gnu.org
2023-04-26  6:57 ` [Bug tree-optimization/108351] [13/14 " rguenth at gcc dot gnu.org
2023-07-27  9:25 ` rguenth at gcc dot gnu.org
2023-11-24 12:43 ` sjames at gcc dot gnu.org
2023-11-24 14:56 ` yann at ywg dot ch
2023-11-24 15:47 ` jamborm at gcc dot gnu.org

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