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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
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109601

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-g268987713c7105c69=
1)
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 m=
ost
people think (the other missed optimization earlier is though).=