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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/109601] Useless branch not eliminated when writing to a union
Date: Sun, 23 Apr 2023 18:58:02 +0000	[thread overview]
Message-ID: <bug-109601-4-bsMXYkDsv8@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109601-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109601

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-04-23
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
x86 duplicated the simple return but never unduplicates it:
(jump_insn 27 12 28 3 (simple_return) 1030 {simple_return_internal}
     (nil)
 -> simple_return)
...

(jump_insn 32 31 33 4 (simple_return) "/app/example.cpp":29:1 -1
     (nil)
 -> simple_return)


But simple_return was only added in GCC 4.7.0 (r0-111280-g268987713c7105c691)
So something else changed.

There is also a missed optimization earlier because jump2 is way late to be
optimizing this case.

Also this is just an issue with return so it might not be as important as most
people think (the other missed optimization earlier is though).

      parent reply	other threads:[~2023-04-23 18:58 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-23 18:26 [Bug target/109601] New: " 67 at mniip dot com
2023-04-23 18:48 ` [Bug rtl-optimization/109601] " pinskia at gcc dot gnu.org
2023-04-23 18:58 ` pinskia at gcc dot gnu.org [this message]

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